ISSN 0289-842X

RIKEN
Accelerator
Progress Report
vol.

29

理化学研究所

The Institute of Physical and Chemical Research (RIKEN)RIKEN Accelerator Progress Report 11 (Q) (Q) lb.
January-December U1/ 1/ ~voL

29!~ it. ~ ~ff ~ jilTThe Institute of Physical find Chemic'" Research (RIK£N)
Wako-shi, Saitama, 351-01 JAPANEditors
A. GotoT. Ichihara

T. Kambara

T. Kobayashi

Y. Kobayashi

T. Okada

I. Shimamura

M. Takamis. Yamaji

F. Yatagai

All rights reserved. This report or any part thereof may not be reproduced in any form
(including photostatic or microfilm form) without written permission from the publisher.
All reports are written on authors' responsibility and thus the editors are not liable for thecontents of the report.

CONTENTS
I.

Page
PREFACE .............................................................................. 1

II.

OPERATION OF ACCELERATORSRRC and AVF Cyclotron Operation

3

Tandem Operation ..................................................................

5

RILAC Operation ..................................................................

6

III.

RESEARCH ACTIVITIES

1.

Nuclear Physics
Stochastic Variational Method with Realistic Potentials

7

Structure of the A = 9 System with Microscopic Cluster Model. . . . . . . . . . . . . . . . . . . . . .

8Magnetic Moments of the Mirror Nuclei 9C and 9Li .................................

9

Magnetic Moment of 11 Be ...........................................................

10

Direct Radiative Capture Process in the 12C(n, ')') 13 C Reaction .......... ... .........

11

Neutron Capture of Nuclei Far from Stability .......................................

12

Interaction Radii of Na-isotopes .....................................................

13

Mechanism of the Inversion between Id and 2s Single Particle Levels ................

14

A Systematic Study of Even-Even Mass Nuclei Up to the Drip Lines in Terms of
the Relativistic Mean Field Theory ........................ ........... ...............

15

Systematics of Interaction Radii of Unstable Sd-Shell Nuclei

16

Nuclear Shell Energies and Deformations in Mass Formulas(1) Theory ......................................................................... .

17

Nuclear Shell Energies and Deformations in Mass Formulas(2) Results ... .... ..... . ......... .... ...................... ..... ................... .

18

Quantum Monte Carlo Diagonalization Method for Nuclear Shell Model ............ .

19

Extensive Hartree-Fock + BCS Calculation with Skyrme Sm: Force ................. .

20

Do Soft Dipole States Exist in Light Nuclei? ....................................... .

21

Giant Resonance States in Neutron-Rich Nuclei .................................... .

22

Double Giant Dipole Resonance States ............................................. .

23

Correlated Ground State and E2 Giant Resonance Built on It ............... ; ...... .

24

Damping of Hot Giant Dipole Resonance as a Linear Irreversible Process ........... .

25

C 4 Symmetry in Superdeformation by Berry's Phase Analysis ...................... .

26.
. 182 0 s ........................................................ .
In
T 1'lt'Ing M ech anism

27

Estimation of Signature Splitting of TAR with GCM ............................... .

28

3D Angular Momentum Projection of Tilted Axis Rotating States ...................

29

Statistical Property of Molecular Dynamics with Wave Packets ......................

30

Antisymmetrized Molecular Dynamics with Stochastic Incorporation of
Vlasov Equation ....................................................................

31

Collisional Damping and the Temperature Dependence of Nuclear Dissipation ........

32

Dissipative Dynamics of Fission Studied with Three-Dimensional Langevin Equation.

33

Quenching of the Coulomb Sum Value ..............................................

34

Symmetry Energy at Subnuclear Densities and the Layer of Non-spherical Nuclei
in Neutron Star Crusts ..............................................................

35

Braking Index Changes from Neutron Star Glitches ...... , ..... ... ........ ... ..... ...

36

Exotic Nuclear Deformation in the Neutron Star Crusts and the Origin of Glitches

37

A Study of Collision Frequency and Particle Density in Ultrarelativistic Nuclear
Collisions by an Event Generator URASiMA ........................................

38

Gluon Distribution Function Using Bag Model and QCD Sum Rule...... ............

39

Lattice-QCD Calculations Using VPP 500 ...........................................

40

Effective Potential Formalism for Dynamical Chiral-Symmetry Breaking in the Dual
Ginzburg-Landau Theory ...........................................................

41

New a-Decaying Neutron-Deficient Isotopes 197Rn and 200Fr .........................

42

New a-Decaying Neutron-Deficient Isotopes 196Rn and 195 At ........................

43

Study of a Decays from Evaporation Residues Produced by the
40 Ar + 232Th Reaction ..............................................................

44

Nuclear Moments and Charge Radii of 175Hf Determined by Laser Spectroscopy

45

Production of Neutron Deficient a-Decaying Hafnium Isotopes 161- 157 Hf Using
RIKEN GARIS/IGISOL ............................................................

46

Measurement of Neutron Spallation Cross Sections ..................................

47

High-Spin States in 148Tb ...........................................................

48

Life Time of High Charged States Isomer ................ ~ . . . . . . . . . . . . . . . . . . . . . . . . . . .

49

Target Dependence of Production Rates of Projectile-like Fragments .................

50

Production and Identification of New Neutron Rich Nuclei 31 Ne and 37Mg with
80 A MeV 50Ti Beam.... . ... ........ ...... .. ...... .. ... ...... ..... ...... .. .. .. .. .. .

51

Giant Dipole Resonance in Hot Rotating Nuclei .....................................

52

Entrance Channel Effect on the Pre-scission Time of Binary Decay for Medium Mass
Nuclei (Mass rv 110) ................................................................

53

Temperature and Excitation Energy of Hot Nuclei Produced in 40 Ar + 116Sn
Reaction at E/ A=30 and 37 MeV/nucleon. ...... ........ ...........................

54

Measurement of the d-p Elastic Scattering at Ed = 270 MeV

55

Elastic Scattering of Polarized Deuterons at Ed = 270 MeV

56

..........,.
C (d, d ) ReactIOn at Ed = 270 Me V . . . . . . . . . . . . . . . . . . . . . . . . . .

57

Precise Experiment on fi + d Scattering at 12 Me V .................................

58

Measurement of the

1259Electromagnetic Moments of 13 0 ....................................................

60

Measurement of the Magnetic Moments of 14B and 15B Using Projectile
Fragmentation Spin Polarization ....................... ........ .....................

61

Electric Quadrupole Moments of Neutron-Rich Nuclei 14B and 15B ..................

62

Branching Ratios of the 14 B Beta Decay .............. ...... .............. . ..........

63

Feasibility Test of Delayed Neutron Spectroscopy for Spin-Polarized Neutron-Rich
Nuclei ..............................................................................

64

States in 16C Using the Transfer Reaction 15C(d,p)16C ..............................

65

Measurement of J3-Decay Branching Ratio of 17Ne into the Ground and First
Excited States of 17F ...............................................................

66

Beta Decay of the Drip Line Nuclei 14Be ............................................

67

Measurement of the Fusion Cross Section of Neutron-Rich Nuclei 29,31 Al + 197 Au ....

68

Scattering of Radioactive Nuclei 6He and 3H by Proton. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

69

Spectroscopy of Halo Nucleus 11 Li ...................................................

70

Effects of Neutron Skin and Halo in 6He, 8He, and 11 Li ..............................

71

Charge Exchange Reactions of 11 Li ...... ........ . ....... ............................

72

Coulomb Dissociation of 8B .........................................................

73

Coulomb Dissociation Reaction and Neutron-Neutron Correlation in 11 Li ............

74

Coulomb Excitation of a Halo Nucleus 11Be .........................................

75

Coulomb Excitation of 56Ni .........................................................

76

Neutron Skin of Na Isotopes Studied via Their Interaction Cross Sections. . . . . . . . . . . .

77

Interaction Cross Sections and Radii of Light Nuclei .................................

78

Structure of 10Li Studied by Pion Double Charge Exchange Reaction
10'B ( 7r-, 7r+)10Li .....................................................................

79

RHIC Spin Project .................................................................

80

Muon Pair Detector System for RHIC Spin Project

81

e

2.

e

Spin-Flip and Non-Spin-Flip Isovector Excitation Observed in the 2 C, 12 N)
and 3 C, 13 N) Reactions at E/ A = 100- 135 MeV..... ... ........... ..... ........... .

Atomic and Solid-State Physics
Resonances in Photodetachment of H- (2p2, 3p e)

83

Angular Distributions of Photoelectrons from Helium. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

84

Double Photoionization of Helium at Low Photon Energies ..........................

85

Scattering Angle Dependence of Electron Impact on O 2 and CO .....................

86

Electron Energy Distribution Functions and Thermalization Time in Methane and in
Argone- Methane Mixture ............................................... . ........ . ..

87

Correlation between the Carbon K-Shell X-Ray Emission Rates in Molecules. . . . . . . . .

88

Charge Transfer Effect on Double Electron Excitation of Helium by Proton Impact ..

89

Electron Capture in Slow 0 +(4S, 2D , 2P)- He Collisions: Effects of Metastable Ions ..

90

Electron Loss from H - under Energetic, Highly Ionized Ion Impact ..................

91

Close-Coupling Calculations of Electron Capture from Circular Rydberg States ......

92

Single- and Double-Charge-Exchange Cross Sections for Arq+ + H2 Collisions. . . . . . . . .

93Electron Capture in H+ + CH 4 Collisions .......................... . .................

94

Double and Single Ionization of Helium and Hydrogen Molecules by Slow Protons
and Antiprotons ....................................................................

95

Muon-Transfer Reaction t + dp,(2s) -+ tp,( n = 2) + d ..............................

96

Strong Induced-Dipole-Field Oscillations in an Excited dtp, Molecule above thetp, (N = 2) Threshold .......................................... .. ..................

97

Coincidence Measurement of Fragment Ions with Final Charge State of Projectile in
Fast Ion -C 60 Collision ............................ ... ...............................

98

Three-Dimensional Recoil-Ion Momentum Analyses in 8.7 MeV 0 7+ -He Collisions .. ,99

Intercombination Lines in Highly Charged Ions ....... . .................. ... ...... ...

100

Observation of a Systematic Deviation between Experimental and Theoretical
Lifetimes for the 3s3p 3 PI Level of High Z Mg-like Ions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

101

Problems Caused by Beam-Related Electrons in Beam-Foil Lifetime Measurements ...

102

Beam-Foil Spectra of Highly Charged, Highly Excited Neon Ion in Visible Region ....

103

L X-Ray Emission Spectra of Copper ......................... " . .. . . . . .. .. .. . . .. .. . .

104

Angular Distribution Measurements of X-Rays from Multiply Ionized Atoms

105

Absolute Cross Sections for Charge Capture from Rydberg Targets by Slow
Highly Charged Ions .................... '. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

106

Optogalvanic Diode-Laser Spectroscopy in Hf I ......................................

107

Measurement of the Isotope Shift in Fe by Resonance Ionization Spectroscopy ..... ..

108

Knight Shift for 13 0 Implanted in Pt ................................................

109

Effect of Ligand Distortion on the Hyperfine Magnetic Field of 61 Ni 2+ Ions in theSpinel Chromites ...................................................................

110

In-Beam Mossbauer Study on Pure Iron Using 56Fe(d, p) 57 Fe Reaction. .. . .. .. . . .. .. .

111

61 Ni Mossbauer Spectroscopy on Cubic Spinel Chromites............................

112

p,SR Study on TlBa2 Y l-xCaxCuOy ............................................ . ....

113

p,±SR Measurement of La2-x(Ba,Sr)xCu04 around x = 0.12 .........................

114{L+SR on Fel+XSb ........... ................................................... ....

115

3.

Quantum Diffusion of Positive Muon in Pure Tantalum.. ... .. ... ... ... ........ .. .. . .

116

Spin Dynamics of p,AI Pseudo-Acceptor Centers in Si Probed by p,-SR

117

p,SR Studies on Magnetic Correlations and Spin Dynamics in Kondo
Semimetal CeNiSn ..................................................................

118

The Spin Dynamics of Polarons in Polyaniline Studied by p,-SR .....................

119

LF J.lSR Studies on Reorientational Dynamics in Solid C 70 Using the
ARGUS Spectrometer ..............................................................

120

Single Event Effect in Power MOSFETs by High-Energy Heavy Ion.. ... .. ...... ... . .

121

Heavy-Ion Irradiation Effects on the Single Crystal La1.8sSro.1sCu04 .................

122

Observation of Columnar Defects in 136Xe+31 Bombarded Layered Materials .........

123

Laser Spectroscopy of Atoms and Molecules in Liquid Helium ..... . ... ..............

124

Behaviour of Xe Atoms in Xe-Implanted Iron.. .. . .. . .... .. .. .... . .. . .. .. .. .. .... .. ..

125

Radiochemistry and Nuclear Chemistry
Differential Recoil Ranges of Reaction Products in the Cu + 14N, 40 Ar
Nuclear Reactions ............. ........ ..... .... ..... . ..... ;.... ..... .... ..... ......

127

Mass Transfer in the Heavy-Ion Reaction of 197 Au Induced by 136Xe

128

eReaction of 4,1S N + 165Ho) and (40 Ar, 14N, + 141Pr) Systems at
Intermediate Energies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

129

Multitracer Study on the Behavior of Various Elements in Atmosphere-Plant System.

130

Determination of Trace Elements in Ferns by Neutron Activation Analysis (I) ........

131

Determination of Trace Elements in Ferns by Neutron Activation Analysis (II)132

Distribution Coefficients of Platinum Group Metals between Soil Solidand Liquid Phase ...................................................................

133

Group Separation of a Multitracer by Solvent Extraction ... .........................

134

Group Separation of a Multitracer by Cation Exchange Column .....................

135

Biodistribution Study of Antibodies Labeled with Multitracer in Mice

136

Study of Trace Elements Uptake by Tumor-Bearing Mice by theMultitracer Technique ..............................................................

137

Separation of a Multitracer from an Au Target Irradiated by Heavy Ions

138

Selective Separation and Reversed Phase Extraction of Zirconium andHafnium from Multitracer Solution ..................................................

139

Metabolism of Trace Elements in Marine Algae: A Study Using the Multitracer ......

140

Biodistribution of Gold Complexes in Mice ..........................................

141

Metabolic and Biochemical Studies of Trace Elements in Zinc-Deficient Rats
(1) Biochemical Properties of the Platinum-Group Elements .........................

142

Metabolic and Biochemical Studies of Trace Elements in Zinc-Deficient Rats
(2) Ionic Radius Dependence of Uptake of Rare-Earth Elements .....................

143

4.

In Vivo Behavior of Various Rare-Earth Elements in Lipogenous Diabetes Model
Mice by Using the Multitracer Technique.. ..... ........ ... ... . ... . ... .. .. . ... ... . . . .

144

Metabolic Studies of Various Trace Elements in Acute Alcoholic Mice. . . . . . . . . . . . . . . .

145

Research in Metabolic Physiology on Space Field by Using the Multitracer
Technique-A Proposal ................................... ,. ... ..... ... .. . ..... ... . ...

146

Preparation of a Multitracer from Heavy-Ion Irradiated Tin by Heating under Reduced
Pressure ............... . ............................................................

147

Time Dependence of Distribution of Trace Elements in Rats Using theMultitracer Technique .......................................................... . ...

148

Multitracer Study on Distribution of Trace Elements in Vitamin D
Overloaded Rats ..................................................... . ..............

149

Multitracer Study on Distribution of Trace Elements in Vitamin D Deficient Rats. . . .

150

Solvent Extraction Behavior of Multitracers by Di(2-ethylhexyl)phosphoric Acid

151

Multitracer Study on Stability Constants of Humate Complexes with Various
Metal Ions .............................................. . ..................... . .....

152

Metabolism of Various Trace Elements in LEC Rats Leading to Acute Hepatitis .....

153

Studies on the Ion Exchange Adsorption Behavior of Strongly Acidic Resin N afion
and Its Application to Analytical Chemistry. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

154

Uptake Behavior of Multitracers in LEC Rats before Jaundice Development .........

155

Biodistribution of Multitracers in Normal, AI-Overloaded and Cd-Overloaded Mice

156

Creating a New Design System Using a Cooled CCD Camera Multi Spectrum
Imager .............................................................................

157

TDPAC of 99Ru Arising from 99Rh in a-Fe203 and EuFe03 .............. . ....... .. .

158

Extraction of an Intense Slow Positron Beam Using He++ Beams from the
AVF Cyclotron .......................................................... . ..........

159

Resistivity Dependence of Positron/Positronium Annihilation in Porous Silicon ......

160

Positron Annihilation Studies on the Interaction between Hydrogen and Defects
in Nickel ........................................ . ...................................

161

Radiation Chemistry and Radiation Biology
Track-Depth Resolved Dynamics of Excited States in Ion Irradiated Rare Gases
near Condensed Phases ........................................................... . .

163

Unusual Temperature-Dependent Decay of Self-Trapped Excitons Formed at HighDensity in Ion Irradiated BaF 2 ................................. . ....................

164

Effect of Heavy-Ion Beams during the Fertilization Cycle of Plants. . . . . . . . . . . . . . . . . . .

165

Enhanced Cell Inactivation at Nonpermissive Temperature ..........................

166

Effects of Ne Ion Beams on the Survival of Arabidopsis thaliana ....................

167

Dependence of Interphase-Death Induction on the LET of Accelerated Neon-Ionsin CHO Cells .......................................................................

168

The Role of DNA Repair on Cell Killing by Neutron and Heavy-Ion Beams ..........

169

5.

6.

Analysis of Mutations in the Human HPRT Gene Induced by Accelerated
Heavy-Ion Irradiations (II) ..........................................................

170

Early Phase Histological Changes of Skin after Carbon Ion Slit-Beam Irradiation

171

Measurement of Potassium, Rubidium and Cesium Influx Rate into Rat
Erythrocytes Using Multitracer Technique. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

172

Translocation of Radionuclides from Plant Leaf Surfaces

173

Instrumentation

Computer Environment around the Accelerator Facility

175

Data Acquisition System for Segment-Ge Detector ...... ......... ...................

176

Development of an On-line Laser Ion Source Using Resonance Ionization in an Ion
Guide Chamber at RIKEN GARIS/IGISOL .........................................

177

Operation and Status of the RIKEN EBIS (REBIS) .... . . .... ..................... ..

178

Development of the Deuteron POLarimeter DPOL ..... .......... ...................

179

Development of Polarized Xe Solid as a Means to Produce Spin Polarization in Stopped
Unstable Nuclei .....................................................................

181

Development of the Detector for Sub-MeV ,B-Delayed Neutron. .. ..... . . .. ...... .. ...

182

Slew Correction for Timing Signals from NaI(TI) Scintillators ........................

183

NaI(TI) Detector Assembly for Low Intensity Radiation (DALI) .....................

184

Summing Amplifiers for Heavy-Nucleus Search Experiments .........................

185

Test of a High-Rate MWDC for Heavy-Ion Detection ............ , . ... ... . .... ... .. . .

186

Construction of a PPAC with High Position Resolution ..............................

187

Heavy Ion Beam Test of Cosmic Ray Telescope for the First Brazilian
Scientific Satellite ............... ... ... ... ... ...... ... ......................... .. ....

189

Progress in Beam Optics for RIKEN-RAL Muon Facility ............................

190

New Data Acquisition System for RIKEN-RAL jlCF Experiment ....................

192

Installation of Tritium Gas Handling System for Muon Catalyzed
Fusion Experiment at RIKEN-RAL Muon Facility. . .. ... ... . .. .. . ..... .. ...... . .. .. .

194

Development of a New jlSR Spectrometer ARGUS ........... ..... ...... ............

196

Development of a Resonance Ionization Buffer Gas Cell for Laser Spectroscopy ofRefractory Elements and Actinides ...... ... ....... ............... ..... ..............

198

A New Beam Line for Material Irradiations in the Ring Cyclotron

199

Material Analysis

RBS Study of Tb-Implanted Sapphire (II)201

Sample Charging Effect on Satellite Spectra of Ion-Induced X Rays ..................

202

Correlation between Seawater Temperature and Sr/Ca Ratios in Otoliths of Red Sea
Bream Pagrus major ..............................................................

203

Whether Ion Beam Attracts Ions in Solutions or Not? ........... ....................

204

IV.

V.

NUCLEAR DATA

Status Report of the Nuclear Data Group205

Measurements of Activation Cross Sections of Energy Up to 110 MeV for
Several Neutron-Induced Reactions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

206

DEVELOPMENT OF ACCELERATOR FACILITIESStatus of RIKEN lOG Hz ECRIS ...................................................

207

Present Status and Future Plans of RIKEN 14.5 GHz Caprice .. .......... ...........

208

E-Field Injection for Extracting Much Faster Pulse Trains or for Enhanced
CW Beams out of an ECRIS Potential-Well .........................................

209

Supporting Evidences of the LLPB Concept to Explain Enhanced High-Charge
State Ion Beam-Current in ECRIS ..................................................

211

Development of Polarized 3He Gas Target ...........................................

213

Development of a New Type of Single-Bunch Selector ...............................

214

Construction of a New Beam Line from the AVF Cyclotron... . . .. . .. . .. . . ...... .. . . .

216

Improvement of the RF Control System for RILAC ............. . ....................

217

Status of a New Injector System for RILAC .........................................

219

Development of RIKEN 18 GHz ECRIS .............................................

220

Development of a Variable-Frequency RFQ Linac for RILAC ........................

221

Misalignment Effect of Vanes on Beam Transmission Efficiency in an RFQ Linac .....

223

Design Study of Siberian Snake Magnet for RHIC-Spin Project ......................

225

Progress of RIKEN RI Beam Factory Project .......................................

226

Conceptual Design of a Frequency-Tunable IH Linac .... .. ...........................

228

Design Study of Sector Magnet of the Superconducting Ring Cyclotron (I) ...........

230

Design Study of Sector Magnet of the Superconducting Ring Cyclotron (II) ..........

232

Design Study of the Injection System of the Superconducting Ring Cyclotron (III) ...

234

Design of a Model Sector Magnet of the Superconducting Ring Cyclotron. ... .. . . . ...

236

Double Storage Rings for MUSES ...................................................

238

Accumulator Cooler Ring and Booster Synchrotron Ring for MUSES ................

240

Design of Booster Synchrotron for MUSES ..........................................

241

Computer Study of Magnet Power Supply for MUSES Booster Synchrotron (BSR) ...

242

Simulation of RF Stacking Injection at Accumulator Cooler Ring for MUSES ........

244

Electron Cooling at RI Beam Factory ...............................................

246

Design of a Lattice of the DSR ......................................................

248

Beam Current Limitations Due to Single-Beam Collective Effects at Double Storage
Rings at MUSES . ..................................................................

250

VI.

Merging Beam-Beam Interaction at DSR ........................................... .

252

Beam-Beam Interaction of Electrons and Ions at Double Storage Ring ...............

254

Luminosity of Electron-Ion Collision in MUSES .....................................

256

An Undulator and the Photon Flux at MUSES...... ..... . .. .... .. .......... ... .....

257

RADIATION MONITORING
Leakage Radiation Measurements in the Ring Cyclotron Facility

259

Dose Rates Due to Residual Activities in the Ring Cyclotron Facility ..... .... ...... .

261

Routine Works for Radiation Safety in the Ring Cyclotron Facility .... ... .... ....... .

263

VII.

LIST OF PUBLICATIONS .... .. ......................................... ............ .... 265

VIII.

LIST OF PREPRINTS ............................................................. .. .... 271

IX.

PAPERS PRESENTED AT MEETINGS .................................................. 274

X.

LIST OF SYMPOSIAXI.

LIST OF SEMINARS ................................................................... . 286

XII.

LIST OF PERSONNEL .... ... ........................ ... .... ..... ...................... . 289

AUTHOR INDEX

285

I. PREFACEThe Report summarizes research activities at the
RIKEN Accelerator Research Facility in the year of
1995. The research program at the Facility has been
pursued under the framework of the project entitled
Multi-disciplinary Researches on Heavy Ion Science.
The program extends over a variety of fields; nuclear
physics, atomic physics, nuclear chemistry, radiation
biology, condensed matter physics in terms of accelerator or radiation, basic studies on energy production
and accelerator cancer therapy, material characterization, application to space science, accelerator engineering, laser technology and computational technology.
The central facility is a heavy-ion accelerator complex consisting of the RIKEN Ring Cyclotron (RRC)
and its subordinate accelerators, the energy-variable
heavy ion linear accelerator (RILAC), and the K = 70
Me V AVF cyclotron. They have altogether delivereda beam time (on the target) of more than 8000 hours.
Twelve laboratories at RIKEN and more than 400 researchers including outside users have participated in
the program.
The Facility has marked a great milestone thisyear by starting two new projects; 1) R&D of theso called RIKEN Radioactive Beam Factory and 2)
RIKEN-BNL collaboration program on spin structure
functions. Having achieved approval of the two new
projects, the Facility is moving towards a new stage ofmajor development.
The project of the RIKEN Radioactive Beam
Factory involves construction of a superconducting
separate-sector cyclotron with K-number around 2400
Me V which serves as the energy booster upon the existing RRC. The beam energy of heavier elements is to become sufficiently high to produce projectile-fragment(PF) beams of a broadened range of unstable nuclei.
The cyclotrons are to be accompanied with dual ringsof synchrotron to enhance experimental perspectives.
We anticipate that the Factory would make a central
contribution to the development of next-generation radioactive beam (RIB) science. Most optimistically the
Factory would be completed around 2002 or 2003.
Design works on the Factory are in progress to proceed to construction of a proto-type superconducting
sector. Meanwhile a major development has been accomplished at the upstream end of the RILAC. A set of
18 GHz ECR ion source and a frequency-variable RFQ
has been completed to significantly improve the beam
output. The apparatus with the upgraded intensity is
an important ingredient of the Factory project.
The Facility carries on an international research
program on muon science in collaboration with the
Rutherford-Appleton Laboratory. The muon beam fa-

cility at the proton synchrotron ISIS has started operation to accommodate versatile research programs using
powerful pulsed muon beams.
The new project on relativistic-energy spin physics
has been formulated as the 2nd international research
program following the first on muon science. It is tobe carried out in collaboration with Brookhaven Nativnal Laboratory. The program aims at investigationof spin related properties of nucleons in terms of the
QCD framework. Spin-polarized proton beams will be
developed and facilitated at RHIC, bringing a new opportunity of physics in the RHIC program. The construction of a muon arm has started as well as R&D
work on Siberian snakes.
The base-line research program using the heavy-ion
accelerator complex has maintained a steady development . Nuclear physics researches have been heavily
associated with radioactive beam experiments. Studies on nuclear synthesis towards the drip lines and very
heavy elements have continued, resulting in identification of new isotopes such as 31 Ne, 37Mg, 197Rn, and
200 Fr.
Spectroscopy on extremely neutron rich nuclei has made a further progress: Inelastic scattering,
charge exchange reactions and Coulomb dissociations
have been extensively applied to study different excitation modes of halo (or skin) nuclei. The ,i3-,-neutron
spectroscopy has been developed significantly. Reactions induced by unstable nuclei offered other unique
opportunities. Sub-barrier fusion reactions with neutron rich nuclei have been measured to investigate
plausible anomaly in cross sections. Measurements ofreaction rates of astrophysical interest have continued.
Among others the measurement of Coulomb dissociation cross section of 8B has been elaborated in relation
to the solar neutrino problem.
Development of the radioactive beams is crucial forthe studies on unstable nuclei at the Facility. Uniquely
the Facility provides three different types of radioactive beams: Firstly intermediate-energy RIB by meansof projectile fragmentation has been most frequently
used, amounting to about 40 % of the whole RRC
beam time. The second type of RIB is the spinpolarized beam which is also produced via PF process.
The beam has been used to determine nuclear moments(g-factor and Q) of a dozen of unstable nuclei including
exotic nuclei such as 17B. The third type of RIB is thehigh-spin isomer beam which is produced via reversekinematics fusion reactions. Beams of heavy isomers
with spins close to 30 n are obtained with considerable
intensity. A study on secondary fusion reactions was
initiated.
Spin-isospin response is another popular subject at1

the Facility, where reactions (d,2He) and (d,d(O+))
as well as heavy-ion exchange reactions are primarily
used. A simple direct-reaction mechanism characteristic of high-energy heavy-ion exchange reactions wasproved to provide a useful means of the spectroscopy.
Atomic physics has been pursued, enjoying an extremely wide energy range of heavy ions covered by
the set of the ECR ion source, RILAC and RRC. A
method of recoil-ion momentum analysis in ion-atomcollisions has been developed using a cold supersonicgas jet target. It allows determination of the final
electronic state and resolves the small scattering angle in the range of 10- 6 radian. The fragmentation of
C 60 molecules in collisions with heavy ions has beenstudied at the RILAC. A study on collisions between
negative hydrogen ions and highly charged energetic
ions has started. An international collaboration program on beam-foil spectroscopy of highly charged ions
was further enhanced in collaboration with Lund U niversity. A series of systematic lifetime measurementsof Mg-like heavy ions has been extended to heavier
elements up to Rh. Basic information for laser andplasma applications is gained.
In the domain of nuclear chemistry nuclear hyperfine
studies have moved in a new phase of development for
in-beam spectroscopy: The following three different
approaches of in-beam Mossbauer spectroscopy were
pursued. Firstly site occupation and atomic jump process of 57Fe in solid rare gases were investigated using Coulomb-excited recoils. An alternative reactionof 56Fe(d,p)57Fe was used to study the dynamic behavior of interstitial 57Fe atoms in a single crystal of Fe.
An attempt to produce high-energy PF beam of theshort-lived 57Mn isotope has been initiated to open a
new domain of Moessbauer spectroscopy.
The multi-tracer technique originally developed at
the Facility continuously cultivated new areas of application. Diabetic mice , LEC rats and atmosphere-plantsystems were newly treated and influx rates of alkali
metals into erythrocyte and labeling of antibodies witha multi-tracer were studied.
Heavy ion beams have offered a variety of means
for material characterization including those facilitating PIXE, Rutherford scattering and channeling effect.
Recently a project on slow positron spectroscopy using
short lived isotopes was started at the AVF cyclotron.
Irradiation effects with heavy-ion beams are studiedin several aspects. In the domain of radiation biology astriking effect was observed in irradiation of heavy ionson tobacco plants. A nitrogen beam elicited mutagenesis in the embryo of the plant when administered during the fertilization cycle and its effect was manifested
in an extremely short period. Recently an intriguing
application of radioactive beam was tested in relation
to the cancer therapy. Use of a radioactive beam may
offer a possibility to spot in real time the location of
the stopped isotopes by means of positron tomography.
A simulation experiment using a radioactive beam of
11 C was performed, demonstrating an encouraging perspective. Heavy-ion beams are also useful to modify
the property of material in a controlled way. In thisrespect a study on the pinning effect of magnetic flux
through high-Tc superconducting materials under theirradiation of high-energy heavy ions is in progress.
For the first time this issue presents a list of seminars
held at the Facility.

Masayasu Ishihara
Director
RIKEN Accelerator Research Facility

2

II.

OPERATION OF ACCELERATORSRIKEN Accel. Prog. Rep. 29 (1996)

RRC. and AVF Cyclotron Operation
M. Kase, N. Inabe, A. Goto, T. Kageyama, 1. Yokoyama, M. Nagase, S. Kohara, T. Nakagawa,K. Ikegami, O. Kamigaito, J . Fujita, H. Isshiki,* H . Akagi ,* R. Ichikawa,* N. Tsukiori,*
R. Abe,* K. Takahashi,* T. Maie,* T. Homma,* and Y. Yano
All beams, which were accelerated with the RIKEN
Ring Cyclotron (RRC) in the one-year duration from
Nov. 1994 to Oct. 1995, are listed in Table 1, together
with fundamental acceleration parameters and a total
time spent for experiments. In this period, a total of 35
kinds of beams, ranging widely in the energy and massspace, was used for experiments. Among of these , 13
kinds of beams, such as 80 MeV I n 50Ti and 7 MeV I n

130Te, were newly added to the list. A proton beamwith the highest energy of 210 MeV , which had been
accelerated only for a machine test in 1991, was firstly
used for experiment.
The total beam time, which was used for experiments , amounts to 202 days. Most of it (86.7%) was
devoted to nuclear physics experiments and the rest(13.3%) to experiments in many other fields , such as

Table 1. RRC beams accelerated during Nov. 1994- 0ct. 1995.
Particle

Charge

H2

1
1
1
1
1
1
1
1
2
6
6
6
7
8
7
8
10
10
10
10
6
14
17
17
7
20
24
25
21
23
25
22
31
22
24

H2 ---4 P
p
pol-d
12C
13C
14N
16 0
180
2°Ne
22Ne

36Ar
40Ar

48Ti
50Ti
59CO
58Ni
84Kr

129Xe
136Xe
130Te
140Ce

RF F
(MHz)
26.2
27.6
29.0
30.1
30.5
32.6
34.2
38.7
32.6
32.6
29.0
32.7
32.6
32.6
35.2
29.0
32.6
24.6
29.0
30.1
18.8
33.0
27.6
28.1
18.8
26.2
26.2
28.1
28.1
28.0
32.7
18.8
28.0
18.0
18.0

h
in RRC
5
5
5
5
5
5
5
5
5
5
5
9
5
5
9
5
5
5
5
5
11
9
5
5
11
5
5
5
10
9
9
11
9
11
11

Inj ector
AVF
AVF
AVF
AVF
AVF
AVF
AVF
AVF
AVF
AVF
AVF
RILAC
AVF
AVF
RILAC
AVF
AVF
AVF
AVF
AVF
RILAC
RILAC
AVF
AVF
RILAC
AVF
AVF
AVF
RILAC
RILAC
RILAC
RILAC
RILAC
RILAC
RILAC

Energy(MeV l u)
80 t
90
100
110
113
135
150 t
210
135
135
100
35
135
135
42t
100
135
70
100
110
7.6
37 t
90 t
95
7.6 t
80 t
80 t
95 t
21 t
26
36
7.6 t
26
7t
7t
Total

Beam time(days)
1.8
1.3
1.3
2.2
2.5
4.5
2.0
1.7
18.9
17.6
13.2
0.4
3.3
6.7
4.8
24 .9
7.8
4.3
4.4
5.9
8.2
0.5
8.8
2.6
6.8
11.8
1.9
5.9
0.4
0.5
0.5
2.8
2.7
16.2
3.6
202.7

t New beams
Sumijyu Accelerator Service, Ltd.

3

biology, medical science, radio-chemistry, healthphysics, and material science. The AVF-RRC operation was performed for 157 days (79%) and the RILACRRC operation for 42 days (21%).
It takes one day to prepare a beam on the average. However a beam tuning time longer than 1.5 days
is sometimes necessary to meet user's special requirements on a strict single-turn extraction, a small beam
spot on target, a well-separated single-bunched beam,and so on.
Stand-alone uses of the two injector have routinely
been made during a time when the other injector is
coupled with RRC. In Table 2 are listed the beams
which were provided against users of the AVF cyclotron. A total of 44 days was spent additionallyfor various experiments on slow-positron beam production, in-beam Mossbaour spectroscopy, and RI production as well as nuclear physics.
In this one year, a total of 14 days of the scheduledmachine time had to be canceled. Main reasons for

Table 2. AVF beams which were used for experimentsfrom Nov. 1994 to Oct. 1995.
Ion source Energy Beam time
Particle RF Fh(MHz) in AVF( days)
MeV/u
2
14.0
0.9
p
23.0
ECR
8.0
2.9
12.3
2
PIS
d
PIS
9.1
17.8
13.2
2
9.5
6.0
19.0
2
PIS
14.0
PIS
1.9
23.0
2
25.0
15.5
2
ECR
9.3
a
ECR
35.0
1.9
18.2
2
ECR
32.0
0.3
17.2
2
27 Al
7.5
16.9
2
ECR
1.5
40 Ar
3.8
1.9
12.0
2
ECR
Total
44.4

4

these unexpected shut-downs were relating to deflectors of both the AVF cyclotron and the RRC. They
sometimes did not work sufficiently due to their unendurable leak currents. A periodic maintenance with
opening a vacuum chamber is necessary in both thecases. Most of beam time which was canceled dueto these troubles could be compensated by shortening
maintenance time or holidays.
Recently a beam of 80 MeV In 50Ti was accelerated
and used for an experiment. To get an enough intensity, we had to use an enriched-material, which isextremely expensive. To save the quantity of it , when
it was charged to the 10 GHz ECR source, a thin alumina (AI 2 .0 3 ) pipe, a hole of which was filled with asmall amount of powder of enriched (50%) TiO , wasused in stead of a normal ceramic rod. It could supply
an 80 MeV In 50Ti beam with an intensity of 8 pnA on
a target for a week at least.
A single-bunched beam is sometimes required byusers as a time trigger for the measurement of time
spectrum. A very compact single-bunch selector,
which consists of a fast beam chopper and a subharmonic buncher , has been successfully developed.
Both the devices are installed in a low-energy injection
line of the AVF cyclotron. As long as a single-turn extraction is strictly achieved in each cyclotron, a puresingle bunched beam with a repetition rate as high as
1 MHz is available.
In the spring of 1995, a beam line, E7e, was newly
built in the E7 room for a stand-alone use of the AVF
cyclotron in place of an old beam line E7b. As the result, the beam course E7b, which had been used for amuon spectrometer of Large 0 , was removed together
with the experimental device. The new beam line wasdesigned for the experiment using a polarized-deuteronbeam. A new experiment on polarized-neutron scattering has just started using it.

RIKEN Accel. Prog. Rep. 29 (1996)

Tandem Operation
E. Vagi, K. Ogiwara, T. Urai, and M. Iwaki
A 1.7 MV tandem accelerator has been newly installed and becomes available for experiment sinceApril, 1995. A large portion of beam time is allotted to machine inspection and beam test. Additional
beam lines are still under construction.
The experimental studies on the following subjects
are being made.
(1) Rutherford Backscattering Spectroscopy (RBS)(a) Behaviour of Kr atoms implanted into aluminium by a channelling method (Muon Science Lab.).
(b) Behaviour of Xe atoms implanted into iron
(M uon Science Lab.).
(c) RBS analysis of Tb-implanted sapphire crystals(Surface Characterization Centre) .

(d) Characterization of oxide films grown on SrTi0 3(Surface Chemstry Lab.).
(2) Nuclear Reaction Analysis (NRA)(a) Lattice location of hydrogen in niobium alloys
by a channelling method (Muon Science Lab.).
(3) Particle Induced X-ray Emission (PIXE)(a) Application of PIXE to biomedical and material sciences: Trace element analysis using energydispersive X-ray spectrometry, and chemical state
analysis using wave-dispersive X-ray spectrometry (Inorganic Chemical Physics Lab.).
(b) Development of an X-ray detector (CyclotronLab.).

5

RIKEN Accel. Prog. Rep. 29 (1996)

RILAC Operation
E. Ikezawa, M. Hemmi, T. Chiba, S. Kohara, T. Aihara,* T. Ohki;* H. Hasebe,*
H. Yamauchi, * and Y. Miyazawa
RILAC has been in steady operation, and has supplied various kinds of ion beams for the experiments.
Table 1 gives the statistics of operation from Jan.
through Dec. 1995. One day of the scheduled beamtime was cancelled owing to the damage of copper
sheets for electric contact of the resonator No.6 : thethin copper sheets (10 cm wide, 7 cm long, and 0.3
mm thick) were melted with too high rf currents. Thisdamage was extended in the region of about one meterin length. Table 2 summarizes the time sharing allotted for individual research groups. The percentage ofthe beam time for RRC was about 45% of the total;
ions of 14N, 18 0, 36 Ar, 40 Ar, 48Ti, 84Kr, 129Xe, 130Te,
136Xe, 140Ce, and 142Ce were injected to RRC. Table
3 gives the statistics of ions used in this year. Amongthem, a 89y14+ beam at the acceleration frequency of
32 MHz is new. The percentage of the beam time formetallic ions amounted to about 36% of the total.

Table 3. List of ions used in this year .
Ion
He
B
C
N

0
0
Ne
Si
Ar
Ar
Ti
Ni
Kr
Y
Zr
Zr
Nb
Xe
Te
Xe
Ce
Ce

Table 1. Statistics of the operation from Jan. 1 throughDec. 31, 1995.
Days%

Beam time

174

47.7

Frequency change

15

4.1

Overhaul and improvement

52

14.2

Periodic inspection and repair

14

3.8

Pb

Mass

Charge state

Days

4
11
12
14
16
18
20
28
36
40
48
58
84
89
90
91
93
129
130
136
140
142
208

I
2, 3
2
3
2,3,5
4
3,4
5
6
5, 6, 87
6
10, II, 13
14
12
12
12
9
9
9, 15
11

5
8
6
2
5
7
10
I
6
39
9
2
13
3
2
2
7
5
13
13
14

11

I

11

I

Days

%

Atomic physics

60

34.5

Solid-state physics

6

3.4

Nuclear physics

6

3.4

Nuclear chemistry2

1.1

Radiation chemistry

16

9.2

Accelerator research

6

3.4

Beam transportation to RRC

78

44.8

We carried out the following machine improvements:(1) In the rf system of six resonators, the servo motor controllers driving the capacitive trimmer were replaced with compact ones designed newly because they
were worn out after many years operation. To geteasy maintenance and stable operation, both automatic tuning and amplitude controllers were also replaced with newly designed ones;l) (2) The power supplies for the quadrupole magnets of the beam transportline were remodeled by replacing the obsolete powertransistors with modern ones; and (3) The stainlesssteel plates (159 sheets in total) mounted in three heatexchangers for RILAC cooling water were replacedwith new ones because of deterioration after the fifteenyears use.
In the 8 GHz ECR ion source, we have tested to produce metallic ions by use of materials such as Gd 20 3
and CaF 2; as a result , we obtained the beam intensityof 2 ep,A for Gd 12 + and 6 ep,A for Ca6+. The yieldof Ca ions with a CaF 2 rod was lower than that witha CaO rod. So far , the ions of 10 kinds of gaseous
elements and those of 42 kinds of solid elements havebeen produced by the 8 GHz ECR ion source.

174

100

References

0.3

Machine trouble
Scheduled shut down
Total

109

29.9

365

100

Table 2. Beam time for individual research groups.

Total1) S. Kohara et al.: This report , p. 217.
Sumijyu Accelerator Service, Ltd.

6

III.

RESEARCH ACTIVITIES1. Nuclear Physics

RIKEN Accel. Prog. Rep. 29 (1996)

Stochastic Variational Method with Realistic Potentials
Y. Ohbayasi, * Y. Suzuki, and K. Varga[few-body systems, stochastic variational method, realistic potentiaL]
We have investigated the application of the stochastic variational methods (SVM)l) to the few-body problems what are treated as either multi-cluster or fewnucleon systems. 2 ) The results are obtained with 'effective' potentials.
N ow we applied the SVM method to the system interacting via 'realistic' potentials, especially to the triton ground state (EExp. = -S.4 MeV). Since solving
the nuclear many-body Schrodinger equation is difficult because of the complexity of the interaction andof the variety of nuclear motion, it is interesting toconfirm whether our method is effective in such case.
Up to now, we selected Reid VS3)and Eikemeier andHackenbroich potential (EH)4) as the 'realistic' potential. The former has the Yukawa function and thelatter has the Gaussians. Both of them include thecentral, spin-orbit and tensor potentials. Because thepotential has non-central parts, the needed channel becomes larger than that of the case with effective potential which has only central part. The orbital angular momentum channels included in the calculation are(f l , f2)L = (0,0)0, (1 ,1)0, (2,2)0, (1,1)1, (2,2)1, (1,1)2,(0,2)2, (2,0)2 and (2,2)2, and the total spin channels
are [(81,82) 812, 83]S = [(1/2,1/2) 0,1/2]1/2, [(1/2 ,1/2)
1, 1/2]1/2 and [(1/2 ,1/2) 1, 1/2]3/2. We solved the triton ground state (J7r = 1/2+) by selecting importantbasis functions on correlated Gaussians.
The application of the few-body problem to the triton system with the 'realistic' potential has alreadybeen investigated by GFMC, ATMS, and Feddeev
groups.S) In the case of Reid VS potential, we get theenergy of -7.6 MeV within 200 basis. Comparative
results are: - 7.0S(05) MeV [VMC], -7.54(10) MeV[GFMC], -7.59 MeV [Faddeev]. We have confirmedthat our method yields better results than the otherwith lower dimension of the basis functions. Figure 1
displays the energy convergence of triton for the different potentials.

Graduate School of Science and Technology,
University

-7.2
-7.3

;;
~

6»

Oil

a..
~

..

-7.4
-7.5

=
=
S -7.6~....

'- , _______ EH:sReid V8

-7.7
-7.8
0

200
100
number of basis

300

Fig. 1. The triton energy convergence of Reid V8 (Solidline) and Eikemeier and Hackenbroich (dashed line).

In summary, we applied the SVM to solve the triton ground state with the 'realistic' potentials. Our
results give larger binding energy than the other methods. Thus we confirmed that our method is also usefulfor 'realistic ' potential problems. For further application, we will extend to the system with more than three
nucleons.
References
1) K. Varga, Y. Suzuki, and R. G. Lovas: Nucl. Phys. ,A571 , 447 (1994).
2) K. Varga, Y. Suzuki, and Y. Ohbayasi: Phys. Rev. ,C50, 189 (1994); K. Varga, Y. Suzuki, and I. Tanihata:
ibid., C52 (1995) in press; K. Varga and Y. Suzuki:
ibid., in press.
3) R. B. Wiringa and V. R. Pandharipande: Nucl. Phys.,
A317, 1 (1979).
4) H. Eikemeier and H. H. Hackenbroich: ibid., A169 , 407(1971).
5) See, e.g. , J. Carlson, Phys. Rev., C38, 1879 (1988).

Niigata7

RIKEN Accel. Prog. Rep. 29 (1996)

Structure of the A

9 System with Microscopic Cluster Model

K. Arai, * Y. Ogawa, Y. Suzuki, and K. Varga[the mirror nuclei of 9Be and 9B, the microscopic cluster model.]Be isotopes, from 8Be to the neutron drip-line I4Be,
have very interesting properties because of the variety of binding mechanism and structure. 8Be is wellknown to have a 2a structure, and 11 Be and I4Be havea neutron halo structure. Our purpose is to investigate the structure of Be-isotopes by a microscopic 2a+ valence neutrons model.
As the start of this investigation, we study 9Be andits mirror nucleus 9B with a 2a + N three-body microscopic cluser model using the stochastic variational
method. l )The two-nucleon interaction used in this calculation is Minnesota Pot. including the L-S force andthe Coulomb Pot. The exchange-mixture parameter u in Minnesota Pot. is taken as 0.94 to reproduce the ground state binding energy of 9Be from thethree-body threshold. The calculated proton radius
rp = 2.39[fm] is in good agreement with the experimental value derived from (e,e) data rp = 2.37[fm]. Our
result of the magnetic moment and electric quadrupole
moment is also in very nice agreement with the experimental values. See Table 1. The probability of total
angular momentum L in the ground state of the 9Be(total spin and isospin are S = ~, T = ~) is about
85% for L = 1 and 15% for L = 2. This L = 2 component is important to reproduce the magnetic moment
and Q-moment. The electron elastic longitudinal andtransverse form factors were also calculated and found
to reproduce experimental data very well. The calculated total reaction cross section for a carbon target atTable 1. The matter, proton, neutron radius rrn,rp,r n andthe magnetic moment: J.l and the quadrupole moment:
Q in the ground state of 9Be.

rrn ( fm )rp (fm)rn (fm)J.l( J.lN )Q (e fm .~ )

cal.
2.50
2.39
2.58
-1.1689
5.13

Graduate School of Science andUniversity

8

exp.3J

800 Me V /neucleon is 850[mb], which is in fair agreement with the experimental value 806 ± 9[mb].
Except for the ground state of 9Be, all the states of
9Be and 9B are above the three-body threshold. The
complex scaling method was used to calculate theseresonance states, and the interaction used here is thesame as the ground state of 9Be. The calculated energy
level and width of ~ -, ~ ~ , ~ - are in good agreementwith the experimental ones. The investigation for the
1+..
2" state IS III progress.
Recently K. Varga et al. studied the structure of 9Li
and 9C with a + (3N) + N + N four-body microscopic
cluster model. 2 ) Because the ground state and the 2.43
Me V ~ - state of 9Be are described well by the present
model, the {3 decay of the 9Li ground state to thesestates is expected to further test the accuracy of theirwave functions or an available wave function of 9Li.
The experimental value of logft for the (3 decay to
the 9Be ground state is about 5.3,3) indicating thatthe (3-decay matrix element is fairly suppressed despite
the allowedtransition. In fact the Gamow-Teller (GT)matrix element, to any state of 9Be which is describedby the a + a + n three-cluster model always vanishes
regardless of the wave function of 9Li . This is mosteasily understood by acting the Hermitian conjugateof the GT operator on the 9Be wave function and bynoting that the spin-isospin part of the a-particle wave
function is fully occupied. The break-up effect of thea particle is needed and we must extended the model
space to reproduce experimental ft value. To see thiseffect, we extended the model space a little as a first
test. One of the a particles is broken to triton and
one proton , then the calculated logft is about 6.1 andgets weak transition. A further investigation is being
made.

-

References

2.37--1.1778±0.0009
5.3±0.3

Technology,

Niigata

1) K. Varga, Y . Suzuki, and R. G. Lovas: Nucl. Phys. ,A571 , 447 (1994).
2) K. Varga, Y. Suzuki, and I. Tanihata: Phys. Rev., C52 ,3013 (1995).
3) F. Ajzenberg-Selove: Nucl. Phys. , A490 , 1 (1988).

RIKEN Accel. Prog. Rep. 29 (1996)

Magnetic Moments of the Mirror Nuclei 9C and 9Li
N. Fukunishi and 1. Tanihata[NUCLEAR STRUCTURE, Magnetic moment, Shell model.]The magnetic moment of a nucleus is one of the basic
probes for the microscopic aspect of the nuclear structure, especially the spin structure of nuclei. Recently,
K. Matsuta and his co-workers reported the magnetic
moment of 9C,1) in which the proton number and theneutron number are highly asymmetric. With the previously determined value of the magnetic moment of
9Li, which is a mirror partner of 9C, they pointed out
the anomalous behavior of unstable nuclei.
Under the assumption of the isospin symmetry andthe use of free nucleon g-factors, the isoscalar magnetic
moment (J.LIS) relates to the expected value of the total spin as J.LIS = J /2 + 0.38(Sz) , where we choose thez-axis to be the quantized axis of the total angularmomentum (J). Figure 1 shows (Sz) for several mirror
pairs whose mass number is odd. Roughly speaking,even numbers of like nucleons are usually coupled togive J = 0 due to the strong pairing correlation andthe last unpaired nucleon mainly contributes to (Sz).
Thus, (Sz) is usually less than 1/2. The mirror pair
9C and 9Li exceed exceptionally this value.
1.0
_ _9

~o.o

c-'ti

. • • •• • ••

0.5

l-

• •

••

v
-0.5

-1.0

I

10

I

I

20

30

40

A (Mass number)

Fig. 1. (Sz) for several mirror pairs.

We analyzed this exotic phenomenon based on theconventional shell model. Our starting point is the pshell model. Several effective interactions reproduce
successfully properties of nuclei in this mass region. 2 )We found in Fig. 2 that all of them failed to reproduce
the present anomaly. The important point is that it
does not mean that all effective interactions previously
proposed have some shortcomings. We demonstrated
that any effective interaction, even if it is unphysical,
cannot reproduce simultaneously the isoscalar and theisovector magnetic moments (J.LIV) in this case. The
reason is as follows. The nucleus 9C has one active
neutron and four active protons in the p-shell. Thus,
possible combinations of the neutron and the proton
spin are only two. The one is (Sn = 1/2, Sp = 0),
where Sn(Sp) is the neutron (proton) spin. The other4~------------------~

3

]
... 2

.3o
<II

>
] 1
o~~~~~~~~~~~

0.9

0.95

1

1.05

1.1

1.15

Isoscalar (J.Iti)

Fig. 2. The isoscalar and the isovector magnetic moments
for the mirror pair 9C and 9Li. The diamonds show theresults of shell model calculation using several effective
interactions. The solid line with black boxes shows thetheoretical upper limit.

is (Sn = 1/2, Sp = 1). In this case, the broken pair ofprotons contribute (Sz). To reproduce J.LIS, the lattercomponent must contribute largely. It results in thestrong reduction of J.LIV because the g-factors of the
proton and the neutron have different sign. Thus, amaximum value of J.LIV exists for a given value of J.LIS
as illustrated in Fig. 2. We found that the present
experimental result exceeds this upper limit.
The previous discussions are based on three assumptions, that is to say, the isospin symmetry, the useof free nucleon g-factors, and the choice of the model
space. We must investigate several effects that are believed to be small for light stable nuclei. We extended
our calculation to include (1) two-particle type excitation from the p-shell to the sd-shell,3) (2) effects of exchange currents and the tensor force with the use of effective g-factors,4) (3) effects due to the coulomb force,the isospin-symmetry-breaking force and the chargesymmetry-breaking force. The last one explains qualitatively the discrepancy between theory and experiment, but these isospin-breaking effects can explain
only 25% of the discrepancy quantitatively. We mustmention that the present calculations do not include
possible effects from loosely bound nucleons or clustering. In this sense, our analysis is incomplete. However,the present analysis revealed how exotic the magnetic
moments of the mirror pair 9C and 9Li are.
References
1) K. Matsuta et al.: Nucl. Phys., A588, 153c (1995).
2) They include, for example, the Cohen-Kurath interaction and the PSDT interaction recently proposed by
Warburton and Brown.
3) The PSDWBP interaction is used.
4) A. Arima et al.: Adv. Nucl. Phys., 18, 1 (1987).

9

RIKEN Accel. Prog. Rep. 29 (1996)

Magnetic Moment of 11 Be
T. Suzuki, T. Otsuka, and A. Muta
[N eutron halo, Magnetic moment.]
Magnetic moments of a neutron-halo nucleus, 11 Be,
are investigated. I) The neutron halo is found to reducethe meson exchange current (MEC) contributions to
the magnetic moment of 11 Be (1 /2i.s.). The calculated
magnetic moment is found to be sensitive to the admixture of I lOBe (2+) x d 5 / 2 : 1/2+ > configuration in
11 Beg .s.. The measurement of the magnetic moment ishighly recommended for the determination of the rateof the admixture of 110 Be (2+) x d 5 / 2 : 1/2+ > configuration in 11 Beg . s..
As for the MEC, the pair, pionic and ~33-isobar
currents due to one-pion exchanges are taken into accoint. We use a halo wave function for v1s l / 2 -orbit
obtained in a deformed Woods-Saxon (WS) potential(f32 = 0.7) since the ground state is considered to bewell deformed. 2 ) Calculated values of the MEC contributions to the magnetic moment for the pure VlS I / 2 state are DJ-L = - 0.076 (-0.117), 0.059 (0.098) and
0.019 (0.052) J-LN for the pair, pionic and ~33-isobar
current, respectively, for the halo (harmonic oscillator(h.o.)) wave function. Reduction of the MEC contribution is found to be due to smaller overlap of a singleparticle wave function of the halo orbit with those ofcore orbits. The net MEC contributions to the magnetic moment, which are small even without the halo
effects, are reduced to 6% of the h.o. value for the deformed WS potential.
Now, we examine how the calculated magnetic moment depends on the rate of the admixture of the
I lOBe (2+) x d 5 / 2 : 1/2+ > configuration. The groundstate of 11 Be is assumed to have the following form: 3)

I 11 Be (1/2i.s,) > = Q I lOBe (0+) x VlS l / 2 : 1/2+ >+ f3l lO Be (2+) x vd 5 / 2 : 1/2+ >(1)
Calculated results of the magnetic moment with andwithout the MEC are shown in Fig. 1. As the configuration is free from the halo, the more the configurationis admixed, the less become the effects of the halo on
the MEC contributions. We also carried out a calculation that takes into account the quenching effects fromhigher-order configuration mixing: g~ff = 0.85 gs 4) (seeFig. 2). Calculated values of the magnetic moment
depend almost linearly on P(IS l / 2 ) = Q2. If the magnetic moment were measured, the probability of the
admixture of the I lOBe (2+) x d 5 / 2 : 1/2+ > configuration in 11 Be g .s. could be determined. It would also
become apparent whether the quenching effects due
to higher-order configuration mixing are important or
not. P(IS l / 2 ) would be determined with an accuracyof rvl0%. The variational shell model (VSM),3) for ex10

-1.5
f.J-N

-1.6
-1.7
-1.8
-1.9

_._,- + MEC(H.O,)-2.0+ MEC(HALO)-2.1-2.2 ..........................~...............~............~...........................~...............~...........................
20
30
40
50
60
70
80
90
100

Fig. 1. Dependence of the calculated magnetic moment ofllBe (1/2t.s.) on P(lS 1 / 2 ). Dashed line denotes the impulse values while dash-dotted and solid lines include
the MEC contributions obtained with h.o . and halo
wave functions for the 1S 1 / 2 orbit, respectively.

-1.4

-1.5
-1.6
-1.7

- -- + MEC(H.O .)

-1.8

-

+ MEC(HALO)-1.9- 2.0 ':"""".....u.~............~..L....~.L........................~........L....~....L.............J
20
30
40
50
60
70
80
90
100

Fig. 2. The same as in Fig. 1 except that the effective
isovector spin g-factor , g~ff = 0.85 gs, is used.

ample, gives P(IS l / 2 ) rv 0.55. A stripping reaction on
lOBe 5 ) yields a spectroscopic factor of 0.77. The measurement of the magnetic moment is now under plan 6 )though it is a hard experiment.
References
1) T. Suzuki, T. Otsuka, and A . Muta: Phys. Lett. B , inpress.
2) A. Muta and T. Otsuka: submitted to Phys. Rev. C.
3) T. Otsuka, N . Fukunishi, and H. Sagawa: Phys. Rev.
Lett., 70, 1385 (1993).
4) W.-T. Chou, E. K. Warburton, and B. A. Brown: Phys.
Rev., C47, 163 (1993).
5) B. Zweiglinski et al.: Nucl. Phys. , A315, 124 (1979).
6) K. Asahi: private communication.

RIKEN Accel. Prog. Rep. 29 (1996)

Direct Radiative Capture Process in the 12C(n,,)13C Reaction
A. Mengoni, * T. Otsuka, and M. Ishihara[Neutron capture, neutron-rich nuclei, neutron halo.]
The neutron capture cross sections for the 12C(n, ,)reaction leading to the four bound state of 13C havebeen calculated 1) in the framework of the direct radiative capture (DRC) model. The incident neutronenergy region covered is 0.0253 eV ::; En ::; 500 keY. A
comparison with experimental results is made possibleby the recent measurements performed at the Tokyo
Institute of Technology.2) A detailed description of themethodology for calculation is given elsewhere. 1) The
main results of the investigation can be summarizedas:1) The DRC model provides a reliable description of
the capture process. In fact, in the energy region underconsideration no compound nuclear state is observed(the first resonance is at En = 2.1 MeV).
2) The role of incident p-wave neutrons is essential
in the representation of the experimental results forthe transitions leading to the 2S 1 / 2 and to the 1d5 / 2
bound orbits in 13C.
3) The calculated cross section due to incident swave neutrons is sensitive to the neutron-nucleus interaction.
4) The calculated cross section due to incident pwave neutrons is essentially insensitive to the neutronnucleus interaction.
Point 4), even though expected from a naive pictureof the neutron-nucleus collision process (in which the pwave neutrons only interact peripherally with the target), is of particular relevance. In fact, on the one hand
it sustains the reliability of the calculation and on theother hand it opens the possibility of using the (n, ,)reaction channel to derive information on the boundstate wave functions. In fact, in the case of p ---+ stransition the capture cross section depends essentiallyonly on the matrix elements

which, in turn, are sensitive only to the final state wave
function. This result is being investigated in order toverify the possibility of directly extracting the radial
component of the bound state wave function from theexperimental (n,,) cross section. In particular, using
this technique it would be possible to directly verify
the existance of exotic (e.g. halo) components in the
wave function of excited nuclear states in stable and/or
unstable neutron-rich nuciei.
References
1) A. Mengoni, T. Otsuka, and M. Ishihara: Phys. Rev.,
C52, R2334 (1995).
2) T. Ohsaki, Y. Nagai, M. Igashira, T. Shima, K. Takeda,
S. Seino, and T. Irie: Astrophys. J., 422, 912 (1994).

Permanent address: Applied Physics Section, ENEA, Italy

11

RIKEN Accel. Prog. Rep. 29 (1996)

Neutron Capture of Nuclei Far from Stability
A. Mengoni,* T. Otsuka, and M. Ishihara[Neutron capture, neutron-rich nuclei, neutron halo, nucleosynthesis of heavy elements.]
It has been recently proposed 1 ,2) to use the neutron
capture reaction channel (or its inverse, the coulomb
dissociation) to study some peculiar structure properties of stable or near-stable nuclei. There are certain conditions which must be satisfied in order to apply this method. In particular, the condition that thedensity of levels has to be low enough to exclude thepresence of nuclear compound states in the incident
neutron energy region must be satisfied. The capture
process which takes place under such conditions has
been called the direct radiative capture (DRC) process. The DRC process of incident ~wave neutrons
captured into bound sand d orbits is particularly suitable as an application of the method because for thisparticular case the matrix elements

Qi:";f = < Wfl TE1 1wi >for the E1 I'-ray emitting transition i ---t f do notdepend sensibly on the neutron-nucleus interaction.
Therefore , the initial state wave function Wi can bepromptly calculated using simple potential models.
Woods-Saxon or even square-well potential can be used
to derive the radial component of the initial scattering
state. 3) On the other hand, the final capturing state
wave function, Wf' directly enters in the matrix elements; hence, the role of the Wf components on andoutside the nuclear surface can be detected in a capture
cross section measurement which provides(J'n"V,I-2k 3 IQ(1)f 12 .
(1,. ---t f) -- 16K
9ti e
t-+
"V
I

<0>:1)=13.3111> (A=12)<0>:1) = 8.3111> (A=14)- - <0>:1)= 4.31lb (A=16)<0>:1)= 1.41lb (A=18)

140
120

:> 100
Q)

~ 80
~
y.:j

60
40
20
O~~~~~~~~~wz=-----~

0.00

0.05

0.10
0.15
0.20
0.25
Center of mass energy [MeV]

0.30

Fig. 1. Astrophysical L:-factor for n + AC(n , ')') and kT =30 keY.

rates for a chain of unstable neutron-rich carbon isotopes, in particular for applications in nuclear astrophysics , where we still must rely on model calculations
for many of the required nuclear reaction rates neededfor example in stellar and / or primordial nucleosynthesis calculations. In all of the cases considered the dominant reaction channel is an E1 , DRC process withp ---t sand/or p ---t d as dominant transitions. The
results are shown in the figure where the astrophysical~-factor.

Here, e is the effective charge for neutrons and k, theemitted I'-ray wave number. Once that the calculation technique has been established and quantitatively
tested for nuclei close to the stability line,2,3) one canproceed further and apply the same method to unstable neutron-rich nuclei. In fact , as the neutron dripline is approached, the neutron binding energy is drastically reduced making the level density low enough tostrongly hinder the compound nucleus component of
the capture process and making the DRC mechanism
more likely to take place.
We have calculated the neutron capture reaction

Permanent address: Applied Physics Section, ENEA, Italy

12160~~~~--~~-.--~.-~-.--~,is shown for the n + 12 ,14 ,16 , 18 C(n , l,) reactions. The
Maxwellian-averaged capture rates (equal to the integral of ~) , are also given in the figure.
References
1) T. Otsuka, M. Ishihara, N. Fukunishi, T. Nakamura,and M. Yokoyama: Phys. Rev., C49 , R2289 (1994).
2) A. Mengoni , T. Otsuka, and M. Ishihara: Proc. of theWorkshop on Experimental Perspectives with Radioactive Nuclear Beams, Padova, 14- 17, Nov. , 1994, in press(1995).
3) A. Mengoni, T. Otsuka, and M. Ishihara: Phys. Rev.,
C52, R2334 (1995).

RIKEN Accel. Prog. Rep. 29 (1996)

Interaction Radii of N a-isotopes
H. Sato[Nuclear interaction radii.]
The determination of nuclear size and density distribution is one of the most important problems in nuclear physics, because these quantities give us quantitative idea of what is the nucleus and also give us astrong criterion for various nuclear structure calculations. In previous works, we studied the systematics
of interaction radii in terms of the interaction crosssection by performing the center of mass corrected
Glauber model calculation including terms up to thesecond order of nucleon-nucleon profile function evaluated with the nuclear density distributions given by
the density dependent Hartree-Fock type variational
calculation,1) and found that the experimental interaction cross sections are nicely reproduced except for
11 Li. 2) We have pointed out that the interaction crosssections nicely satisfy the additivity relationship given
bywhere Rp and R t are the interaction radii of the projectile and target nuclei, which are defined respectively
by the interaction cross sections of identical nuclei, as

We also pointed out that the interaction radii R defined above can be understood as an energy independent characteristic nuclear radius in the nucleusnucleus scattering like the charge radius in the electron scattering. In this work, we extend the study tothe interaction cross sections of N a isotopes on a C
target by employing Skyrme ill (SKIII) interacion in
the calculation of the nuclear radial distribution. Theinteraction cross sections and the interaction radii obtained are summarized in Table 1, and compared withexperimental data. 3) Here we note that, though the1£7/2 neutron state of 32N a obtained is unbound by
0.087 MeV in this calculation, its radial wave function
may not so differ from the real one because of a large
centrifugal barrier in the potential. We find that theexperimental values are nicely reproduced (expect for
32N a), and that the idea of the interaction radius defined through the cross section does also work nicely.

Table 1. The interaction cross sections and interaction
radii of Na-isotopes (here the interaction radius of C is
2.595 fm).
A
20
21
22
23
24
25
26
27
28
29
30
31
32

CTexp(mb)
1,086 (11)1,100 ( 9)1,092 (16)
1,147 (12)1,185 ( 9)1,211 (16)1,229 (18)1,265 (10)1,281 (22)1,318 (15)1,358 (41)1,395 (61)

CTeal (mb)
1,075
1,090
1,110
1,130
1,150
1,170
1,205
1,235
1,275
1,300
1,325
1,350
(1,355)RA(fm)
3.250
3.295
3.345
3.395
3.450
3.510
3.600
3.690
3.780
3.845
3.905
3.970
(3.990)

References
1) H. Sato and Y . Okuhara: Phys. Lett., 162B, 217 (1985);
ibid., 168B, 305 (1986); Phys. Rev., C34, 2171 (1986).
2) I. Tanihata et al.: Phys. Lett., 160 B, 380 (1985); Phys.
Rev. Lett., 55, 2676 (1985).
3) T. Suzuki et al.: Phys. Rev. Lett., 75 , 3241 (1995).

13

RIKEN Accel. Prog. Rep. 29 (1996)

Mechanism of the Inversion between Id and 2s
Single Particle Levels
Y. Sugahara, K. Sumiyoshi, H. Toki, A. Ozawa, and I. Tanihata[relativistic mean field theory, unstable nuclei.]
The physics of unstable nuclei attracts much attention. In nuclei far from the stability line, we have already found very interesting phenomena such as theformation of neutron halo and neutron skin. Near the
drip lines, an interesting phenomenon was found recently. The experimental data indicate that 2S 1 / 2 andId 5 / 2 single particle levels could be inverted in somelight nuclei. We study this phenomenon in the mean
field picture.
First of all, in order to clarify the reason for the inversion of 2s and Id levels, we consider a simple problem. Let us solve the radial Schrodinger equation with
the Woods-Saxon potential, V(r) = -Vo/(1+exp[(rR) / a c ]). By changing the diffuseness parameter a c , weexamine the relation between the shape of the potential and the inversion of the two levels. If we take atypical value, 0.6 fm for a c , the potential has the normal shape as shown in Fig. l(a). In this case, 2s and Id
levels appear in the normal order. When we increasea c to 1.2 fm, the shape of the potential changes to theone in Fig. 1 (b). The flat part near the center vanishes
and the tail becomes larger. In this case, the inversion
can happen as shown in Fig. 1 (c).
ac =1.2fm

ac =O.6fm
2

4

8

4

10

0

6

10

0

r[fm]

-10

r [fm)

·10

~ -M
:::;

>"u ·M

:;.30

> ·30

What provides then such an enlarged tail and makes
the flat part vanish? We find that the isovector potential plays an essential role. In the meson theory, thedifference between the proton and the neutron densities creates the isovector potential. Therefore, theisovector potential has a peak near the surface if the
proton and the neutron radii are different, where thedifference between the proton and the neutron densities is the largest. On the other hand, the isoscalar potential has a similar shape to the total density. Hence,
the addition of the isovector potential makes its flatpart near the center vanish and the tail part enlarge
as the case of the use of a c = 1.2 fm.
In order to demonstrate the above discussion, we
calculate the single particle energies for 2S 1 / 2 and Id 5 / 2
levels of 14C by the RMF theory with TM2 parameter
set. In the RMF theory, p meson provides the isovector
potential. Hence we change only the strength of the pN coupling gp, fixing other parameters. The calculated
results are shown in Fig. 2. As gp increases, 2s and Id
levels come close each other and the inversion occurs
at gp
5. So far, we have discussed the effect of the
isovector potential for the inversion only in the case ofneutrons. The isovector potential acts also on protons.
However, its influence is completely opposite to thecase of neutrons. In fact as shown in Fig. 2, when gp
becomes large, the difference between 2s and Id levels
increases for protons.
I"V

~

-40

-40

<a)

·SO

......,

·SO

1

~ ·14
-

if ·16

2s

"

....

... ,. '1>.-*'

"

.
Id

(c)

Fig. 1. Pictorial representation of the relation between the
shape of the potential and the order of 2s and 1d levels.
Here, the parameters for the Woods-Saxon potential
are taken as Va = -50 MeV and R = 4.3 fm. The
potential shown in (a) is for the case with the diffusenessa c =0.6 fm, while the one in (b) with a c = 1.2 fm . The
corresponding single particle energies of 2s and 1d levels
are shown in (c); the left result corresponds to a c = 0.6
fm and the right one to a c = 1.2 fm.

14

\.

RMF

(I)

·18

-'-,-,--------------------------

12

4~~~~~~~~~~~

o

2

4

6

8

(18)

(22)

(32)

(49)

(73)

gp

Fig. 2. The single particle energies for 14C with the RMF
theory as a function of gp. The results for the neutron
2S 1 / 2 and 1ds/ 2 levels are denoted by the solid and dotted curves, and those for the proton 2S 1 / 2 and 1d s/ 2
levels are denoted by dashed and dash-dotted curves,
respectively. As references, we show the corresponding
symmetry energy for each value of gp in the parentheses
in unit of MeV.

RIKEN Accel. Prog. Rep. 29 (1996)

A Systematic Study of Even-Even Mass Nuclei Up to the Drip
Lines in Terms of the Relativistic Mean Field Theory
K. Sumiyoshi, D. Hirata, 1. Tanihata, Y. Sugahara, and H. Toki
[nuclear structure, deformation, relativistic mean field theory.]
The recent advance at the radioactive nuclear beamfacilities provides us with an explosive number of information on unstable nuclei. We are having the experimental data such as masses, radii and deformations of
unstable nuclei in a wider region of the nuclear chart
than before. The studies of exotic nuclei with suchdata have revealed the novel phenomena such as neutron halos 1 ) and neutron skins 2 ) and bring new findings
in nuclear physics. 3 ) Under this situation, we are eager
to exploit the general feature of the nuclear properties
using a reliable many body theory in the whole regionof the nuclear chart.
We study the ground state properties of even-evenmass nuclei up to the drip lines in the relativistic mean
field (RMF) theory with axial deformation. The RMF
theory, which is a phenomenological model based on
the recent success of the relativistic Brueckner Hartree
Fock theory,4) has been successfully applied to the description of the properties of stableS) and unstable
nuclei. 6 ) Motivated by the recent RMF study on the
shape coexistence and transitions of isotopes ,7) we extend further the study to the whole region of the nuclear chart in order to explore the systematics of nuclear properties.
We perform the constrained RMF calculations on
the quadrupole moment and obtain all the possible
ground state configurations from the energy curves using the supercomputer VPP500 at RIKEN. We adopt
the TMA parameter set 8 ) and find that the total binding energies agree with the experimental data within
3 MeV when we select the deformation of the absolute
minimum for each nuclide.
We show in Fig. 1 the calculated f3 deformation ofeven-even mass nuclei ranging from Z = 8 to Z = 50
up to the drip lines. We see the strong deformations
around Z = 38 rv 42 with N = 38 and 60, which
are suggested to be deformed magic numbers by theexperiments. 3) It is interesting to remark the disappearance of the magic numbers N = 20, 28, and 50 in

the neutron rich region. The thick neutron and protonskins are generally seen for nuclei far from the stability
and its thickness can be large as 1 fm for very neutronrich nuclei.

Fig. 1. The f3 deformation in the N-Z plane. The prolate and oblate shapes are denoted by closed and open
circles, respectively, in the scale shown in the legend.

We are extending the analysis to the region beyond
Z = 50 up to the super heavy region in order to explore
the general trend in the nuclear chart.g) Possible triaxial deformations are also being studied in the triaxial
RMF code in the cases of the coexistence of prolate andoblate deformations observed in the present study.
References
1) I. Tanihata et al.: Phys. Rev. Lett., 55, 2676 (1985).
2) I. Tanihata et al.: Phys. Lett., B289, 261 (1992).
3) J. H. Hamilton: Treatise on Heavy Ion Science, Vol. 8,
ed. D. A. Bromley, Plenum, New York, p . 3 (1989).
4) R. Brockmann and R. Machleidt: Phys. Rev., C42,
1965 (1990).
5) Y. K. Gambhir et al.: Ann. Phys., 198, 132 (1990).
6) D . Hirata et al.: Phys. Rev. , C44, 1467 (1991).
7) D. Hirata et al.: Phys. Lett., B314, 168 (1993).
8) Y. Sugahara: Doctor thesis, Tokyo Metropolitan University (1995).
9) D. Hirata et al.: in preparation.

15

RIKEN Accel. Prog. Rep. 29 (1996)

Systematics of Interaction Radii of Unstable Sd-Shell Nuclei
H. Sato[Nuclear interaction radii.]
Recent study of the size of unstable nuclei with theuse of the secondary unstable nuclear beams suggeststhat some extremely neutron rich nuclei, like 11 Li, canhave a halo type neutron distribution. Here we report another possible type of peculiar behavior of thesize of unstable nuclei: Thus far the nuclear size of amass number A nucleus is believed to be proportional
to A 1/3. However, the nuclear interaction radius ofextremely neutron rich nuclei, which is defined by theinteraction cross section of the identical nuclei of mass
number A such as

can show possible degeneracy or reversion in its mass
number dependence. In a previous work,1) we showthat experimental interaction cross sections of Na-.0isotopes on a C target 2 ) are nicely reproduced withthe center of mass corrected Glauber model calculation including the terms up to the second order of a
nucleon-nucleon profile function evaluated with the nuclear density distributions given by the density dependent Hartree-Fock type variational calculation. 3) We
also pointed out that the interaction cross sections
nicely satisfy the additivity relationship given by

We extend the study to the interaction cross sectionsof nuclei from 0 to Ca isotopes filling the neutron sd
shell. Figure 1 shows the neutron number dependenceof the interaction cross sections on a C target calculated with SKill interaction. As shown in Fig. 1,
we can expect possible reversion of the mass number

1450

e 13.50.S§ 12.50

·ilu
It.!

11.50

~

e 10.50 :

u

9.50
8

-0
~p

9
-JC-F

--s

10

11
-6-Ne
-o-Cl

12

13

14

neutron #15-&-oNa-JC-Ar

16

17

18

19

20

-Ai
-M-Ca

Fig. 1. The neutron number dependence of the interaction cross sections
on a C target calculated with SKIll interaction.

dependence of nuclear interaction radii especially ataround a neutron closed shell of N = 20. The size of
28
0 is larger than that of 33 Al with SKill. This kindof reversion is also found with many other types ofinteractions except SKV (SKV shows degeneracy of
Ro :::;: RF :::;: RNe). This kind of reversion is due to asmall binding energy of the neutron Id 3/ 2 state andalso to rather large binding energy dependence of the16

size of the neutron 2S 1/ 2 state having no centrifugal
barrier.
References
1) H. Sato: This report , p. 13.
2) T. Suzuki et al.: Phys. Rev. Lett., 75, 3241 (1995).
3) H. Sato and Y. Okuhara: Phys. Lett., 162B, 217 (1985);
ibid., 168B, 305 (1986); Phys. Rev., C34, 2171 (1986).

RIKEN Accel. Prog. Rep. 29 (1996)

Nuclear Shell Energies and Deformations in Mass Formulas(1) Theory
M. Uno, H. Koura,* T. Tachibana, ** and M. Yamada**[shell-energy, deformation.]
A new method is devised, based on three assumptions, for estimating shell energies of deformed nuclei
from spherical shell energies. The first assumption is
on the relation between the shell energy and the occupation probabilities of spherical single-particle levelsin the deformed nucleus. More specifically, we assume
that the intrinsic shell energy comes only from thedifferences between the spherical single-particle levels
and their structureless positions which are defined asa more uniform distribution of single-particle levels.
Thus, we describe it as
Ein(Z, N) = J-L

L

WP., ( Z , N ) (e p., - ep.,)

1/

+ J-L

L

Wn.,(Z , N) (en., - en.,) ,

(1 )

1/

where Cjv (v = 1,2,3 ... , and j = n or p) is a singleparticle level in the spherical potential, E j v its structureless position, and Wjv (Z , N) the occupation probability of the v-th spherical single-particle state in the
deformed nucleus (Z, N). The constant f.l (0 < f.l ::; 1)
is to take into account a possible reduction of the shellenergies from the values of the extreme single-particle
model.
The second is a possibility of expressing the occupation probabilities in the deformed nucleus as superpositions of those in appropriate spherical nuclei. Fromthese assumptions we can derive the expression for the
intrinsic shell energy of the deformed nucleus as
Ein(Z, N) =L

where pj(r;Z,N) and pOj(r;Z,N) (j = p,n) are averaged distributions in deformed and spherical nuclei,
respectively. These equations imply the possibility ofdetermining the mixing weights by comparing averaged
di'3tributions in deformed and spherical nuclei. According to this inspection, we practically determine themby considering nuclear shapes as'.

Wn (N , Z , N) -_ - .2...
do'occCr(N'»
471'
dN'
.

(4)

Here, rlocc(r(N')) is the occupied solid angle (seeFig. 1). Equations (2) and (4) are sufficient to determine the intrinsic shell energy. Furthermore, an appropriate average deformation energy is prepared including, in addition to usual surface and Coulomb energies,
two somewhat phenomenological energies: one related
to the proton-neutron displacement, and the other tothe favorableness for prolate shapes which may be understood as due to the part-time formation of clusters.
The ground-state shell energy of the deformed nucleus
and its equilibrium shape can be obtained by minimizing, with respect to changes of deformation parameters , the sum of the intrinsic shell energy and the average deformation energy. In our method we can also
obtain the potential-energy surface plotted against deformation parameters. A more detailed explanation
has been reported in Ref. 2.
deformed nucleus

Wp(Z'; Z, N)Eop(Z' , N)

z,

+

L

Wn(N' ; Z , N)Eon(Z , N').

(2)

: sphere;/N'

Here, Eop(Z' , N) and Eon(Z, N') are the proton andneutron shell energies of spherical nuclei, respectively,
which are expected to be obtained by an appropriate method'!) Then, in order to determine the mixing
weights Wp(Z';Z,N) and Wn(N' ;Z,N) , we make thethird assumption on the relation between the occupation probabilities and the radial nucleon distributions
averaged over all directions. From this we can derive
the expressions,pp(r ; Z , N) =Wp(Z'; Z, N) pop(r; z', N),
(3a)

L
z,

Pn(r;Z,N) =L

Wn(N' ; Z,N) POn(r;Z , N'),

(3b)

N'

Department of Physics and Applied Physics, Waseda
University
Advanced Research Center for Science and Engineering,
Waseda University

Fig. 1. Illustration of occupied solid angle Oocc(r(N')) in
the case of prolate deformation.

References
1) M. Uno, T. Tachibana, M. Takano, H. Koura, and M.
Yamada: Nuclei Far from Stability 6 / Atomic Masses
and Fundamental Constants 9, Bernkastel-Kues, (lOP132), p. 117 (1992); H. Koura, T. Tachibana, M. Uno,and M. Yamada: JAERI-Conf 95-008, p. 250 (1995);
M. Uno, KURRI-TR-405 , Research Reactor Institute,
Kyoto Univ. , p. 82 (1995).
2) H. Koura, M. Uno, T. Tachibana, and M. Yamada:Technical Report, No.95-25, Advanced Research Center
for Science and Engineering, Waseda Univ., p. 1 (1995).

17

RIKEN Accel. Prog. Rep. 29 (1996)

Nuclear Shell Energies and Deformations in Mass Formulas(2) Results
M. Uno, H. Koura, * T. Tachibana, ** and M. Yamada**[shell-energy, deformation.]
According to the prescription explained in our preceding paper in this report , we numerically calculate
ground-state shell energies of deformed nuclei and theirequilibrium deformations. Here, we use the shell energies of spherical nuclei which have been obtained
through a certain method with including up to pairing
effects. 1) They are roughly shown in Fig. 1 for neutron
shell energies Eon, and in Fig. 2 for total spherical shellenergies Eop + Eon. We assume nuclear shapes as could
be expressed within Y 2 and Y 4 deformations. In Fig.
3 is shown the energy lowering D-.Edef caused by deformation, that is, the difference between the shell energyof a deformed nucleus Esheff and its spherical shell energy Eop + Eon. In Fig. 4 the deformation parameterQ2 is roughly shown.

150

100

Energy lowering
L\~ef = S,heff-~

80
f\j

Q)
.0

E

:J
C

60
•

l1£;", =0 MeV
l1£;", ~- 1 . 0
6£;,., ~-2 . 0• -2.0> l1£;,. , ~-3 . 0, -3.0> l1£;" , ~-4 . 0-r -4.0> l1£;,., ~-5 . 0
lIE -5.0> l1£;,.,

c

B

ea.

<>

0.0>
• -1 .0>

40

20

20

40

60

80

100

120

140

neutron number N

Fig. 3. Energy lowering caused by deformation ~Ed ef.

Neutron sphericalshell energies ~n100

Deformation parameter U 2

CD.0§c 100

80

c
o

(5

a.

•

o
•

50

,

+
)I(

100

50

E;,." 4.5 MeV
4.5>E;,.2 3.0
3.0>E;,.2 1.5
1.5>E;,.2 0.0
0.0>E;,.2-1.5- 1.5>E;,.2-3.0-3.0>E;,.2-4.5- 4.5>E;,.

200

150

Q>

.0

E
:J

60

C

C

o

o

c.

250

neutron number N

Fig. 1. Neutron shell energies for spherical nuclei Eon.

20

40

60

80

100

120

140

neutron number N

100

Spherical shell energies~=~p+~nFig. 4. Deformation parameter Q2.

80
f\j

Q)
.0

E
:J

60

C

E;, ~

C

0

'0
0..

40

5.0 > EO ~<>2.5 > EO ~0.0
0.0> E;, ~ 2.5,

20

5.0 MeV•2.5- 2.5 > EO ~- 5.0- 5.0 > EO ~- 7.5+ - 7.5> EO 2- 10.0
lIE

20

40

60

80

100

- 10.0 > EO

120

140

neutron number N

Fig. 2. Total spherical shell energies Eop + Eon.
Department of Physics and Applied Physics, Waseda
University
Advanced Research Center for Science and Engineering,
Waseda University

18

It is noted that in Figs. 3 and 4 are shown the numerical results only for the existing nuclei without predictions, which is solely because of the problem of computational time. It is, except for the same problem,comparably easy in principle to extend our calculation
to include higher-multipole deformations, Y 6 etc. We
are now striving to get overall results which are available for prediction as well.
References
1) T. Tachibana, M. Takano, and M. Yamada: JAERI-M
91-032, p. 395 (1991); H. Koura, T. Tachibana, M. Uno,and M. Yamada: JAERI-Conf 95-008, p. 250 (1995);
M. Uno: KURRI-TR-405 Research Reactor Institute,
Kyoto Univ. , p. 82 (1995).

RIKEN Accel. Prog. Rep. 29 (1996)

Quantum Monte Carlo Diagonalization Method for
Nuclear Shell Model
T. Otsuka, T. Mizusaki, and M. Honma[Nuclear Structure, Nuclear Shell Model, Quantum Monte Carlo Approach.]
Recently we advocated the quantum Monte Carlodiagonalization method,1) which is introduced as an
approach having both the advantage of the quantum
Monte Carlo method and that of the direct diagonalization of the Hamiltonian matrix. The present approach reduces drastically the basis-dimension problem of the direct diagonalization, and overcomes the intrinsic problems of the quantum Monte Carlo method,i.e., sign problem etc. Up to now, we showed its validity by applying it to the Interacting Boson Model(IBM) and nuclear shell model. The formulation of
the present theory is shown in Refs. 1 and 2. In thefollowing Fig. 1, we show the typical results in the caseof the nuclear shell model. This is the case of 24 Mg
with the MSDI force. The dimension of entire Hilbert
space is over 30,000, while in the QMCD calculation

30

-86

>C>

t...
Q)

(A)

25 ~

4+
3+,4+

20 ft..

c:

2+

LU

-2+

A

~ 15
V

10

(8)

-

,...

~~

-

l

-

5 r-

-0+
-94
0

200

400

600

o '--. ..
o

I

200

.

I

--L

400

L

600

QMCD basis number

QMCD basis number

Fig. 1. (A) Energies and (B) expectation values of the angular momentum of low-lying states asfunctions of the QMCD basis dimension. The M = 0 space is considered. The exact values are shownby horizontal bars.

we can get well convergent eigenvalues within the 600
QMCD dimensions. Moreover, readers find that our
method gives the excited states in contrast with theshell model Monte Carlo method. 3 ) These results show
the promising future of the present method.
N ow we are pursuing to investigate the huge shellmodel calculation with the realistic shell model interaction.

References
1) M . Honma, T. Mizusaki, and T. Otsuka: Phys. Rev.
Lett. , 75 , 1284 (1995).
2) T . Mizusaki , M. Honma, and T. Otsuka: Phys. Rev., C ,submitted.
3) W . E. Ormand et al.: ibid., C49, 1422 (1994); C. W.
Johnson et al.: Phys. Rev. Lett. , 69 , 3147 (1992).

19

RIKEN Accel. Prog. Rep. 29 (1996)

Extensive Hartree-Fock + BCS Calculation
with Skyrme sm ForceN. Tajima, S. Takahara,* and N. Onishi
NUCLEAR STRUCTURE, 2 ~ Z ~ 114, Skyrme-Hartree-Fock method,
SIll force, quadrupole moment, nucleon skin.
We have done an extensive Hartree-Fock + BCS calculation with the Skyrme sm force for 1029 even-evennuclei with 2 ~ Z ::; 114 and N ranging from outside theproton drip line to beyond the experimental neutronrich frontier (by a few neutrons).
The feature of our calculation is a three-dimensional
Cartesian-mesh representation of single-particle wavefunctions, while most of the other methods for deformed nuclei express the single-particle wavefunctions
by the expansion in a harmonic oscillator basis. An advantage of the mesh representation is the capability totreat nucleon skins and halos. On the other hand, theycannot be described efficiently in the oscillator-basis
expansion because the asymptotic form of wavefunctions for large r is determined by the basis. Anotheradvantage is that one can treat various shapes without
preparing a basis specific to each shape. In contrast,with the oscillator expansion method, one has to adjust the oscillator frequencies w x , wY ' and W z such thatthey are optimized for the shape and radius of the resulting solution.
We have utilized an HF + BCS code EV8 developed
by Bonche et al. l ) In order to apply it to an extensive calculation, we have modified the code in several
aspects, e.g., we have developed (1) a method to determine the pairing force strengths based on the continuous spectrum approximation, (2) a method to accelerate the convergence to the HF + BCS solution using
an external quadrupole potential, and (3) a novel-form
correction formula for the total energy due to the finite
mesh size.
Comparing the resulting nuclear ground-state
masses with experimental data and predictions byother mass models, we have found that the smoothbehavior of the Skyrme SIll force is very good.
The electric axial quadrupole moments of our solutions agree well with the intrinsic moments deduced
from experimental B(E2)j , except nuclei with small
quadruple moments. We have defined the deformation parameters aZm for the HF + BCS solutions as
those of the uniform-density sharp-surface liquid drop
having the same monopole, quadrupole, and hexadecapole moments as our solution has. The magnitudesof thus-defined non-axial deformation parameters arevery small (ja22j, ja42j < 10- 4, ja44j rv 10- 3) for all theground and the first excited solutions. The differenceof shapes (a20 and a40) between protons and neutrons
Institute of Physics , College of Arts and Sciences, Universityof Tokyo20

is small, too. We have also calculated the energy difference between the oblate and the prolate solutions
and found a clear difference between below and above
the N = 50 shell magic.
We define the nucleon skin as in Ref. 2. We havefound for our 1029 ground-state solutions that theskin grows monotonously and regularly as nucleons areadded to the nucleus. On the other hand, the halo
thickness grows very slowly except near the drip lines,
where it changes the behavior completely and expands
very rapidly. We have also observed that the neutron
skin tends to make the density distribution more spherical.
All the results of the HF + BCS calculations reported in this paper are available electronicallyas an anonymous ftp service on the internet:
ntl.c.u-tokyo.ac.jp. See a file read.me in the home
directory for instructions. The available quantities
are the binding energies, the Fermi levels , the pairing gaps, proton and neutron moments (r2 , r2Y2 ,O,
r 2Y 2,2, r 4y 4,o, r 4Y 4,2, r 4Y 4,4), the skin thicknesses,
the halo radii, the proton/neutron/mass deformation parameters (a20, a22 , a40 , a42, a44, Ro, po) of
1029 ground states and 758 first-excited local minima. Single-particle spectra and density distributionsof protons and neutrons are also obtainable for eachsolution. Postscript figures displaying the results andsome FORTRAN source codes to analyze the results
are also provided.
The authors thank Dr. P. Bonche, Dr. H. Flocard,and Dr. P.-H . Heenen for providing the HF + BCS code
EV8. They are also grateful to Dr. T . Tachibana for
the TUYY mass formula code, to Dr. S. Raman for thecomputer file of the B(E2)j table, and to Dr. P. Moller
for discussions on the results of the FRDM calculations. About 20% of the calculations for this paper
were performed with a computer VPP 500 at RIKEN,
while the remainder were done at the Computer Center of the University of Tokyo with a financial support from RCNP, Osaka University, as RCNP Computational Nuclear Physics Project (No. 94-B-01). A
detailed version of this paper has been submitted to
Nuclear Physics A for publication.
References
1) P. Bonche et a l. : Nucl. Phys., A443, 39 (1985) .
2) N. FUkunishi, T. Otsuka, and I. Tanihata: Phys. Rev.,
C48 , 1648 (1993).

RIKEN Accel. Prog. Rep. 29 (1996)

Do Soft Dipole States Exist in Light Nuclei?
H. Kurasawa* and T. Suzuki[NUCLEAR STRUCTURE soft dipole states.]
Recent experiments make it possible to study not
only the ground states, but also the excited states of
unstable nuclei. New modes peculiar to unstable nuclei are expected to be observed, and to provide new
information on nuclear properties. One of them is a
soft dipole mode,1) which is defined to be a harmonic
vibration of the core nucleus against the excess neutrons. The dipole mode, unlike the giant dipole statesof stable nuclei, may be excited without increasing thesymmetry energy, so that the excitation energy would
be very low, compared with that of CDR.
Recently, low lying dipole states have been observedin light unstable nuclei. For example, in 11 Li the excitation energy is about 1 MeV. 2) Those may be candidates of the soft mode, since their strength for electromagnetic excitation almost exhausts the molecular
sum-rule value3 ) as to the degrees of freedom between
the core and the excess neutrons; in 11 Li the core isconsidered to be 9Li. This fact , however, is not sufficient to draw a conclusion. Indeed, the post acceleration of the fragment observed in the Coulomb dissociation indicates that the lifetime of the excited states
is too short for the dipole oscillation,4) and that thereaction may be a direct breakup.4-6)
We have shown from the sum rule point of view thatthe soft dipole states with low excitation energy do notexist in light nuclei. 7 )First, we write the classical nuclear four-current according to the definition of the soft dipole mode. It isnecessary for defining the amplitude of the dipole oscillation. Next, the microscopic nuclear four-current forthe soft mode is derived from the model-independent
sum rules. Comparing it with the classical current, we
can obtain a constraint on the product of the amplitude and the excitation energy, which depends on thenumber of the excess neutrons and those of protons
and neutrons in the core. If we use the experimental
value of the excitation energy for 11 Li, the sum rule result yields the amplitude of the soft dipole state whichis comparable with the nuclear size. This means thatthe observed state is not the soft dipole states. Suchstates are expected to appear only in heavy nuclei.
References
1) K. Ikeda: Nucl. Phys., A538, 355c (1992).
2) T. Kobayashi et al.:Phys. Lett., B232, 51 (1989).
3) Y. Alhassid et al.: Phys. Rev. Lett., 49, 1482 (1982).
4) K. Ieki et al.: ibid., 70, 730 (1993).
5) T. Nakamura et al.: Phys. Lett., B331, 296 (1994).
6) S. Shimoura et al.: preprint RIKEN-AF-NP-177.
7) H. Kurasawa and T. Suzuki: Pmg. Theor. Phys., 94,
931 (1995).

Department of Physics , Faculty of Science, Chiba University

21

RIKEN Accel. Prog. Rep. 29 (1996)

Giant Resonance States in Neutron-Rich Nuclei
H. Kurasawa* and T. Suzuki[NUCLEAR STRUCTURE neutron-rich nuclei, giant resonance states.]
Stable nuclei have a dipole state which is an oscillation of protons against neutrons, and is called a giant
dipole resonance state (CDR). In neutron-rich nuclei,
the dipole state is expected to be decoupled into twomodes. 1) The one is called a skin dipole mode which isan oscillation of the excess neutrons against the core
nucleons. In halo nuclei, this is called a soft dipole
mode. The other is the core dipole state where neutrons of the core oscillate against the protons of thecore. The excess neutrons do not participate in thisoscillation.
The giant quadrupole states (CQR) of stable nuclei
would be also decoupled into two modes in neutronrich nuclei. 2 ) In the giant quadrupole states, all nucleons participate in the quadrupole oscillation. The oneof the decoupled states is a neutron mode or skin mode
which is a vibration of excess neutrons only. The corenucleon density does not change the shape. The otheris a vibration of the core nucleons only. The excess
neutrons do not participate in the vibration.
We have studied whether or not the new modes provide us with more information on the nuclear effective force than CDR and CQR did. 3 ) For this purpose
we have used a macroscopic model which shows theabove classical pictures. The theoretical basis of themodel is provided by the model-independent sum rules.

Department of P hysics, Faculty of Science, Chiba University

22

The macroscopic model makes it more transparent howeach mode depends on the nuclear effective force , than
microscopic models do.
We have shown that when using Skyrme force, themodel gives analytic expressions of the excitation energies for the various modes. It is seen that each mode
depends on the force parameters in a different way.
For example, the excitation energies of the skin dipole
modes are almost independent of the symmetry potential. This is because the energy-loss due to the oscillation of the protons against the excess neutrons iscancelled by the energy-gain due to the oscillation of
the core-neutrons. It is also true in the skin quadrupolecase, and those excitation energies are dominated by
the isoscalar potential. The core modes are also studied and their dependence on t he nuclear force is shown
to be different from that of t he giant resonance statesin stable nuclei.
References
1) P. G. Hansen and B. Jonson: Europhys. Lett., 4, 409(1987).
2) T. Otsuka: privat e communication.
3) H. Kurasawa and T. Suzuki: Proc. 3rd IN2P3-RIKEN
Symp. on Heavy Ion Collisions , T. Motobayashi et al.
(eds.) , World Scientific, Singapore, p. 269 (1989).

RIKEN Accel. Prog. Rep. 29 (1996)

Double Giant Dipole Resonance States
H. Kurasawa* and T. Suzuki[NUCLEAR STRUCTURE double giant dipole states.]
In the last decade, pion double-charge exchange andrelativistic heavy-ion reactions provided us with signatures on the existence of new giant resonance states in awide range of nuclei. 1,2) Those are called the "double"
giant dipole resonance states (DGDR), because the reactions are due to a multistep process and the observed
excitation energy is close to twice (1.91 ± 0.02) that of
the well-known giant dipole resonance states (G DR).1)
The G D R is then called a "single" giant dipole resonance states. Resonance states are characterized, in
addition to the excitation energy, by the width andthe excitation strength. The width of DGDR is compared with that of GDR and observed to be by 1.60 ±0.03 times wider than that of GDR.1) The strength isestimated with various models, but most of the calculations underestimate the experimental values. 1 )The folding model has been used extensively toanalyze experimental data. 1) Assuming independent
phonon excitations of GDR, the model explains wellthe excitation energy and width of DGDR. The excitation energy is twice that of GDR, and the width,
which is given by the square root of the variance ofthe strength function, is J2 times that of GDR. The. excitation strength, however, is not explained in thismodel. Both pion and heavy ion reactions have observed the strength which is about twice that of thefolding model. 1)
We have investigated the excitation energy, strength
and width of DGDR as model-independently as wecan. 3 )We have shown that the strength of DGDR is de-termined by model-independent sum rules. The sum
rules give a relationship between the strengths of GDR
and DGDR. If the mean excitation energy of DGDR
is twice that of GDR, the DGDR strength is given by
2S 2 , where S denotes the G D R strength. Since thefolding model, assuming DGDR to be independent excitations of GDR, satisfies the sum rules, the discrepancy between the folding model and experiments is notdue to the model of the nuclear structure, but may beowing to assumptions for the reaction mechanism.
The mean excitation energy and width of DGDR are
studied according to Tomonaga theory.4,5) We can derive a rather model-independent relationship between
the mean energies of DGDR and GDR, and also a relationship between the variances of their strengths. It
is shown that the mean energy of DG D R is twice thatof GDR, while the width of DGDR larger than J2times that of GDR. These results are consistent withexperiments, and obtained without assuming independent phonon excitations, in contrast with those of thefolding model.
References
1) H. Emling: Prog. Part. Nucl. Phys., 33, 729 (1994).
2) Ph. Chomaz and N. Frascaria: Phys. Rep., 252 , 275(1995).
3) H. Kurasawa and T. Suzuki: Nucl. Phys., A597, 374(1996).
4) S. I. Tomonaga: Prog. Theor. Phys., 13, 467; 482(1955).
5) T. Suzuki: 1. de Phys., 45, c4-251 (1984).

Department of Physics, Faculty of Science, Chiba University

23

RIKEN Accel. Prog. Rep. 29 (1996)

Correlated Ground State and E2 Giant Resonance Built on It
M. Tohyama[Density matrix theory, correlated ground state, E2 giant resonance.]
Using the Lipkin model as a model hamiltonian,
we have recently demonstrated 1) that a stationary solution of a time-dependent density-matrix formalism(TDDM) can be obtained with an adiabatic method:
starting with the Hartree-Fock (HF) ground state, we
gradually turned on the residual interaction in time.
The obtained stationary solution was a good approximation for the exact solution of the model. In thisreport we discuss the applicability of the adiabatic
method to realistic nuclei taking 16 0 as an example.
We also study the effects of a consistent treatment of
the initial ground state on the energy spectrum of theE2 giant resonance in 16 0.
TDDM determines the time evolution of a one-bodydensity matrix p and a two-body density matrix P2,
and consists of the following three coupled equations
for a single-particle wave function '!/Jet) an occupation
matrix naa and a correlation matrix C a /3a /3 / :o~==----------------------~/3{'c5- C a /3{'c5 (,8I v la';3)]'

Correlation.....

e!l -80~

W

HF:::~-- ~-140 -;---__..--__--.--____-,---__---.-____~
02345
tlt

Fig. 1. Time evolution of the total energy, correlationenergy and HF energy in TDDM.
80.-------------------------~

60
-;.~

40

v

20

§v.l

0

>
~

S

(2)

-40
Q)

(1)

ifinaa ' = L[(aJ3/ v Ir 8)C{'c5a ' /3.__---M--..W--.,-...

:>
6 -60

l

l

-20

-20

where h(l, t) is the mean-field hamiltonian and v
the residual interaction. The explicit expressions for
Ba/3a ' /3 Pa/3a /3 and Ha/3a ' /3 have been presented inRef. 2. To obtain a correlated ground state, we use theadiabatic method: we start with the HF ground statein which Is and Ip single-particle states are fully occupied and make the residual interaction time dependent
as
I ,

l

1

E [MeV]1(4)
where we choose vo=-330 MeV fm 3 . The correlation,
HF and total energies thus calculated are shown in Fig.
1 as a function of time for two different values of 7:
7 = 5 X 10- 23 s (dotted line) and 7 = 50 X 10- 23 s (solidline). As shown in Fig. 1, the oscillations in the correlation and HF energies are drastically reduced when
7 is increased from 5 x 10- 23 s to 50 X 10- 23 s, and thetotal energy is almost saturated as a function of 7.
The E2 giant resonance built on the correlated
ground state is excited by boosting the single-particle
wave functions '!/Ja(1) at t = 57 where 7 is 50 X 10- 23 s.
The E2 strength distributions are shown in Fig. 2.

24-40 -t-------,-------..--------.--------l
o
10
20
30
40

Fig. 2. E2 strength distributions in TDDM with the
HF ground state (dotted line) and with the correlated
ground state (solid line).

Solid line denotes the E2 resonance built on the correlated ground state and dotted line that on the HF
ground state. Both distributions have a bump around
20 MeV but only the latter has a structure in the low
energy region (below 10 Me V). We interpret this structure as an admixture of the E2 modes built on excited configurations. It is found that the mixing of
spurious components in the E2 mode built on the HF
ground state is eliminated with the use of the correlated ground state. 3 )References
1) M. Tohyama: Prog. Theor. Phys. , 92 , L905 (1994).
2) M. Gong and M. Tohyama: Z. Phys. , A335, 153 (1990).
3) M. Tohyama: Prog. Theor. Phys., 94, L147 (1995).

RIKEN Accel. Prog. Rep. 29 (1996)

Damping of Hot Giant Dipole Resonanceas a Linear Irreversible Process
N. D. Dang* and F. Sakata**[HOT NUCLEI, Giant Dipole Resonance, Nonequilibrium Statistical Mechanics.]
It is now well-established that the observed giant
dipole resonance in hot nuclei (the hot GDR) has theapparent width, which increases strongly as the excitation energy goes up, and saturates at around 130 Me V
in the case of Sn isotopes. Most theoretical studies in
the last decade can rep rod uce the centroid energy ofthe hot GDR, but still give different, sometime controversial explanations regarding its width.
Recently we have developed a new approach,l) which
treats explicitly the irreversible coupling between thecollective degrees of freedom to the non-collective ones.
In the case of the hot GDR, the collective degrees of
freedom are the ph phonon states, while the pp and hh
configurations consist only of non-collective degrees of
freedom within the finite-temperature RPA. This irreversible coupling leads to the thermal damping of thecollective ph phonon states, associated with the hot
GDR, when these phonons are propagating throughthe heat bath. We show in this report the relation between this microscopic description and a macroscopic
interpretation of the hot GDR. We consider the hot
GDR as a statistical state, which is slightly deviatedfrom the thermal equilibrium state under the influenceof a temperature-dependent external perturbation. If
one restricts the consideration to the evolution of asingle collective phonon, responsible for the hot GDR
excitation, the equation for the phonon propagation
through the heat bath can be written as
1[7] - Wv - Pv(7])]G~(7]) = 271"

(1)

The polarization operator Pv (7]) arises at non-zerotemperature in Eqn. (1) due to the irreversible coupling between the hot GDR and the heat bath via thenoncollective pp and hh configurations. The imaginary part of its analytic continuation into the complex
energy plane defines the thermal damping of the phphonon as a function of energy 7]. The complex admittance can be expressed in terms of the Green function
G (7]). The normalized relaxation function'll (t), associated with the energy dissipation of the GDR to theheat bath, is derived from the Fourier transform of thecomplex admittance. If w(t) has good exponential decaying behavior w(t) ~ exp( -tITe), the GDR thermal
damping width can be extracted as the reverse of therelaxation time Te:S-)

As an application we consider a simplest realization
for the hot GDR in a system with mass A = 112, which
is provided by a schematic model. It consists of fourdegenerate equidistant shells, which are symmetricallylo~ated at both sides of the Fermi level and interact via
the separable dipole-dipole force. With increasing thetemperature up to T ~ 2.5- 3 MeV the relaxation timedecreases drastically. However starting from T ~ 2.5-3
MeV it remains almost the same (Fig. 1). The analysis
also shows that motional narrowing in hot GDR may
occur if the thermal damping is small and, moreover,
only at rather high temperature (T ;::: 4.6 MeV, i.e.
much higher than what has been predicted in Ref. 2),
where the hot GDR is expected to disappear. 3 )l~=---_______________,.......

.....
~ 0.4~__~~~____~~___________________

"

~,

0.2

~, " "\:.'"~~........

.......

_---._---....._------__"·~i_-:-;.::;-._~=--____

0L---0~.2-S--0-.~5--0-.~7~5~~1~~1~.~2~5~1-.~5~1=.~7?S~2

t!l1t,(MeV-I)

Fig. 1. Normalized relaxation function at finite temperature: T = 0.5 MeV (thick solid), T = 1 MeV (thinsolid), T = 1.5 MeV (thick dashed), T = 2 MeV (thindashed), T = 2.5 MeV (thick dash-dotted), T = 3 MeV(thin dash-dotted), T = 4 MeV (dash-double dotted),
T = 6 MeV (dotted). The horizontal line is lie.

References
1) N. Dinh Dang and M. Baldo: "Perpsective of Nuclear
Physics in the Late Nineties," Hanoi, March, 1994,
World Scientific, Singapore, p. 212 (1995); N. Dinh
Dang and F. Sakata: INS-Rep.-1079, INS, Univ. Tokyo,
Dec. 1994, p. 28 (1994).
2) B. Lauritzen, R. A. Broglia, W. E. Ormand, and T.
D¢ssing: Phys. Lett., B207, 238 (1988).
3) J. Kasagi and K. Yoshida: Nucl. Phys., A569, 195c
(1994).

On leave from the Institute of Nuclear Science andTechnique, Vietnam Atomic Energy Commission, Hanoi,
Vietnam
Theory Division, INS, University of Tokyo
25

RIKEN Accel. Prog. Rep. 29 (1996)

C 4 Symmetry in Superdeformation by Berry's Phase Analysis
K. Sugawara-Tanabe and K. Tanabe*[C 4 symmetry, superdeformation, Berry's phase.]
Recently, C 4 symmetry has been observed for thesuper deformed bands over the mass region of A r-v 130,
150 and 190. The energy levels show a bifurcation of
fJ.I = 4 given by E(I) = Eo(I) + (- )a 4 /2co , where
1= a4mod 4. Here we propose a new idea to produce
fJ.I = 4 staggering without introducing the hexadecapole interaction.
At superdeformation both positive and negative parity levels are contained in a shell, which is a trigger toproduce small / softness. Then this very small asymmetry inft.uences the stable rotation, although the axial symmetry is still preserved. Now the rotationalfrequency has the time-dependent component fJ.w(t)produced by this small asymmetry in addition to theoriginal rotational frequency Wo along the rotational
axis. We use the idea of a Berry's phase, i.e. therapid variable (wo) is inft.uenced by the slow variable
wP ' which is the average frequency of fJ.w(t). Thenthe eigenfunction in the body-fixed frame (b.-f.f.) is

Department of Physics, Saitama University

26

J;

given by I~ >= exp( -i fJ.w(t)· ldt') exp(i,a(t)la >,where Ia > is the solution of the stationary rotation
with frequency Wo in b.-fJ., and the Berry's phase /a(t)can be derived by 'Ya =< alfJ.w(t) . ila >. Here wemust remark that /a(nTp) = 0 where Tp = 27r /w p withinteger n. We use the rigid triaxial rotor Hamiltonian, and then the small asymmetry term is given by~ (I~ + I:') (1/:12 - 1/ Ji). Classical mechanics gives
the following relation between wp and Wo for a triaxial
rotor: (w p /wO)2 = (:11 - :12)(:11 - :13)/(:11:12) for thecase of :11 2:: :12 » :13' N ow we consider the case ofcommensurable number 7] in Wo / wp = n + 7] (n integer) and adopt 7] = ~ (7] = ~ gives the same results).
The first order perturbation gives an energy shift b..E
in addition to Eo , which has the order and the factorof (-) ~ Vi. This agrees with the experimental observation. We can apply the same technique to the caseof 7] = ~.

RIKEN Accel. Prog. Rep. 29 (1996)

Tilting Mechanism in 1820s
T. Horibata and N. Onishi[tilted rotation, three-dimensional cranking, ,-deformation.]
Recently we demonstrated the existence of newstates in 1820S in which the nucleus is in stationary
rotation about an axis tilted from the principal axes ofthe mass-quadrupole moment.1) Since the energies ofthe states are lower than those of the one-dimensional
cranking states, our results suggest an interpretation
for the backbending phenomena somewhat different
from the standard mode1. 2 ) Therefore, it will be ofgreat importance to make clear what mechanism is responsible for stabilizing the tilted axis rotation in thisnucleus. This problem is elucidated by analyzing therespective roles of terms in the hamiltonian. In thecase of J = 141i the energy takes minimum at 'l/J = 27°
with its value E = - 208 ke V along the prime meridian, and hence the analysis is made intensively in theregion of interval from 'l/J = 0° to 50°.
We plot the respective energies contributed fromthe one-body part (kinetic energy) , the quadrupolequadrupole interaction (Q-Q force) , the pairing force
and the total binding energy as a function of northlatitude in Fig. 1. Each energy is normalized to zeroat 'l/J = 0°, and only its variation is illustrated. While
the total energy describes a rather gentle curve whose
variation is small within less than ,....., 1 MeV, the partial energies vary substantially by a typical value of rv3
MeV. The energy contribution from the Q-Q force isseparately given by the f.L = ±2 and f.L = 0 terms.

>
OJ

6

>-

e>
OJ
c

w

.,
-2

We divide the region into three intervals following
their characteristics. In the first region from 'l/J = 0°
to 20°, the rotation alignment of protons strongly suppresses their own pairing correlations and makes themoment of inertia large. Therefore the rotation of the
protons carries a significant amount of angular momentum, and reduces the angular momentum of theneutrons. This results in the recovery of the pairingcorrelation of neutron. In this region the decrease of
the kinetic energy acts as the counter force against the
combined effect of the increase of the total pairing energy (reduce the pairing correlations) and the energy
from the Qo.Qo part of the interaction.
It is found from the calculation that the Q2 components have a large fraction of partial contribution fromthe particles in the natural parity orbitals of either proton or neutron. The contribution from the particles in
the natural parity orbital is particularly large in thefirst region, and the effect also appears in the behavior of "Q2.Q2 part" indicated in the figure in the same
region. Especially, at the equilibrium point, the contribution of particles from the natural parity orbitals
acts strongly as a driving force to make the tilted angle
large.
In the second region in the interval from 'l/J = 20°
to 40°, the pairing force and the Q-Q force playa roleas the driving force to tilt the rotating axis while therather rapid increase of the kinetic energy, which is
the result of large ,-deformation due to increase of theQ2.Q2 part, pushes back the tilted angle as if it acts asa restoring force. In the third region, the triaxiality is
reduced, and the nuclear shape rapidly changes toward
the axially symmetric rotor.
The essential mechanism of the tilted axis rotation in
our calculation is explained by the competition process
between the kinetic energy and the energy of the Q-Q
force, especifically the force leading to the triaxiality.
In the present calculation, the proton positive-parity
states and the neutron negative-parity states, that isnatural parity orbitals , turn out to be responsible forthe occurrence of the TAR. Detailed discussions are
given in the paper. 3 )- 3~~~~--~--~--~~~--~--~--~~

o

10

15

20

25

30

35

~

.s

50

North-latitudeFig. 1. The kinetic energy, the pairing energy, the energy
contribution from the Q-Q force and the resultant totalbinding energy as a function of north-latitudinal angle
at J = 14n.

References
1) T. Horibata and N. Onishi: Phys. Lett. , B325, 283(1994).
2) F. S. Stephens and R. S. Simon: Nucl. Phys., A183,
257 (1972).
3) T. Horibata and N . Onishi: ibid., A596, 251 (1996).

27

RIKEN Accel. Prog. Rep. 29 (1996)

Estimation of Signature Splitting of TAR with GeM
T. Horibata, M. Oi, and N. Onishi[tilted rotation, generator coordinate method, signature splitting.]
A self-consistent three-dimensional cranking calculation 1) based on HFB for 1820s has brought about aninteresting result,2) in which tilted axis rotating (TAR)
states are more stable than the states rotating about
the principal axis of mass-quadrupole moment (PAR).
This fact implies that the intrinsic states become morestable through mixing of the odd angular momentum
members in the wave functions. Namely the tilted axis
rotation breaks the symmetry of signature 3 ) in the intrinsic states, which are composed of even and odd
angular momentum states. This feature is quite favorable to a possible interpretation for the experimental
fact that the energies of odd angular momentum members are very low; these states are considered to be thesame members of the yrast band. The odd angularmomentum members split upward from the even angular momentum members because of the signature
splitting.
We estimate the signature splitting caused by thequantum tunneling between two wells located symmetrically with respect to the plane including two principal axes of the mass-quadrupole tensor, which will becalled the equatorial plane. The tunneling is describedin terms of the generator coordinate method (GCM),4)
in which the north-latitude 'ljJ along the prime meridian
is employed as a generator coordinate.
The generator wave function J0. ('ljJ ) is determined by
the variational equation of Hill-Wheeler. 4) The integral
equation,J[H('ljJ, 'ljJ') - Eo. N('ljJ, 'ljJ')] Jo.('ljJ')d'ljJ' = 0 ,(1)

is solved to calculate the splitting energy, which is adifference of energy of the lowest anti-symmetric statefrom one of the lowest symmetric state.
The norm kernel is first diagonalized. We took 31
points of grid with 4° step from - 60° to 60° for thenumerical integration. All the eigenvalues should bepositive and decrease rapidly as the node number n
is increased. The discretized hamiltonian matrices are
diagonalized again to obtain energy eigenvalues.
The energy eigenvalues of the five lowest states for
J = 141i are depicted in Fig. 1 as a function of thenumber of states employed. We may choose a number
by looking at the energy spectra which form a plateauvs. the increase of number of states. We found a very
stable plateau for the lowest symmetric state (even an-

28

MeV

r-------r---..,-----,-----,.----,...,: ~1~~\ct-- - -.- .- - .-.
1.0

1.... ...--.•..,-.\-.. ---.. - ---+.--.-.. --...

- ---+~

·1.5

25

30

Fig. 1. The energy spectra for J = 141i in g-band as
a function of the number of states employed in diagonalization. The energy is measured from the one for
the PAR state for each J-value, and the arrows with
"TAR" indicate the energy position of the local minima, i.e., TAR states.

gular momentum) and the first excited state of odd
angular momentum. The signature splitting in g-bandis expected to be in the range from 200 ke V to 800
ke V. On the other hand any significant energy separation could not be obtained in s-band in our calculation, though we could not judge where the truncationof states should be made. We can see two doublets
whose energy differences are within 200 ke V. In orderto reproduce the experimental spectra, the depth of the
double wells seems too deep in s-band. 5 ) The present
calculation of GeM does not seem stable enough todraw a reliable value for the signature splitting, because the path of tunneling is restricted to the prime
meridian.
References
1) A. K. Kerman and N. Onishi: Nucl. Phys., A361, 179(1981).
2) T. Horibata and N. Onishi: Phys. Lett., B325 , 283(1994).
3) A. L. Goodman: Nucl. Phys., A230 , 466 (1974) .
4) D. L. Hill and J. A. Wheeler: Phys. Rev., 89 , 1102
(1953).
5) T. Horibata, M. Oi, and N. Onishi: Phys. Lett. , B355 ,
433 (1995) .

RIKEN Accel. Prog. Rep. 29 (1996)

3D Angular Momentum Projection of Tilted Axis
Rotating States
M. Oi , N. Onishi, and T. Horibata
NUCLEAR STRUCTURE Angular momentum projection, Tilted Axis Rotating States (TAR),
generator coordinate method (GCM), overlap kernel.
We have found the tilted axis rotating (TAR) solution in 3D Cranking Calculation based on HFB.1) We
then solved the Hill-Wheeler equation;2)j['H( 1j;, 1// ) - E o< N( 1j;, 1j;' ) lfa (1j; ')d1j; ' = 0 ,(1)

the energy and norm kernels are defined as;( ~~~: ~:~ ) = < ~(1j;)1 (~ ) 1~(1j;') >,(2)

and, the many-body wave function is written as,
Iw > = jd1j;fo«1j;)I~(1j;) >,E(n)== In < ~( 1j; ) I R(n)I~(1j;) >(6)= ~Tr [ ln(ut Rt (n)u + v t RT (n)V)],(7)

2

rithmic overlap is evaluated as; where U and V are theso-called uv-matrices in HFB theory, and 0 = (B, ¢, X).
(B , ¢) represents the direction of the rotation axis, and
X is the rotation angle.
Then, we consider the derivative of €, i €(O). On
one hand, it is calculated approximately, that is,tx

i aa €({) , 4>, x) ~ €( {) , 4> , x + .6.x) - €({) , 4>, x) + O(.6.x) ,(3)

where I<I>( ~ ) > represents the TAR solution labeled bya tilting angle ~ being a generator coordinate.
A weight function f (~ ), is expanded 3 ) by the orthonormalized set that diagonalizes N;(4)where Uk(~ ) and nk are determined bywhich still contains the ambiguity of the branch. But,
the derivative is expressed without ambuguity;4)ai ax €(n) = Tr[j({} , 4»p(n)],d1j;' N(1j; , 1j;')Uk(1j;') = nkuk( 1j; ).

(5)Practically, we truncate the expansion in finite
terms. When the weight function f (~) is truncatedat the (a + 1)-th order, it is written as "fa(~)".
Energy eigenvalues , {Ea}, depend on the number of
the terms, but it is expected that the eigenvalues converge as the number increases. In our results, the convergence of the eigenvalues depends on the constrained
angular momentum. While we obtained a wide plateau
in the energy-vs.-number curve for a certain angularmomentum, we had a gentle down-slope for another.
The latter causes a fatal deficiency for the calculation,
because it is a sensitive problem to determine where
we should truncate the expansion.
The angular momentum projection is one way to get
rid of this shortcoming. Since our solution of TAR was
obtained by the HFB equation that violates the rotational symmetry, the angular momentum is not a goodquantum number. Only its expectation value is what
we know. When the width of the angular momentum
distribution is large, the constraint on the angular momentum seems insufficient.
First, we calculate the norm and energy overlap kernels; Nand H. The kernels are multi-valued functions because they involve square root. To determine
the branch of N, we use helpful formulae ;4) the loga-(9)where j(B, ¢) is a one-body angular momentum matrix
about the rotation axis, and p(O) is a density matrix.
After these formulae are compared with each other,
it is feasible to set the proper branch in €(O).
Next , the projection matrix is calculated 5 )
I

j

(8)

.6. X

X

21 + 1P MK (1j; ) = ~j

I.

dnDMK(n)< ~( 1j; )IR(n)I~( 1j;) >,(10)

where D1rK(O) is the Wigner's d-function and R(O)is the rotation operator.
It is, then, feasible to evaluate the probability of thestates with a certain angular momentum in the cranking solutions, which contain the TAR and PAR (pricipal axis rotating) states. The trace of the projection
matrix gives the probability. 6) It is expected that in
the PAR states even numbers of angular momentum
have major fraction compared with odd ones, whilemore odd states are included in the TAR states.
Finally, we are planning to solve again the HillWheeler equation with the help of the projected TAR
states, which are obtained 5 ) as;

1~ ~ (1j; ) >= LgKPL- K (1j; )I~( 1j;) > .

(11)

K

References
1) T. Horibata and N . Onishi: Phys. Lett. , B325 , 283(1994).
2) T. Horibata et al.: ibid., B353 , 433 (1995).
3) P. Ring and P. Schuck: The Nuclear Many-Body Problem (1980).
4) T. Horibata and N. Onishi: Prog. Thear. Phys ., 46,
1650 (1980).
5) K. Hara et al.: Nucl. Phys. , A385, 14 (1982) .
6) S. Islam et al.: ibid., A326, 161 (1979).

29

RIKEN Accel. Prog. Rep. 29 (1996)

Statistical Property of Molecular Dynamics with Wave Packets
A. Ono and H. Horiuchi[antisymmetrized molecular dynamics, statistical property, nucleon-emission, wave packet.]
Recently, there is a controversyl,2) on the statistical property of molecular dynamics models withwave packets such as the antisymmetrized molecular
dynamics 3 ) (AMD) which are developed in nuclear
physics. We first clarify that there coexist mutually
opposite two statistics in the AMD framework: One isthe classical statistics of wave packet centroids and theother is the quantum statistics of the motion of wave
packets which is described by the AMD wave function.
We examine the statistical property of wave packet
centroids by using the framework of micro canonicalensemble of the nuclear system with realistic effective two-nucleon interaction. The calculated relation
between the excitation energy E and the temperature Te has turned out to be just the linear relation
E / A = 3Te ) which means that the statistical propertyof the wave packet centroids is completely classical.
This is a rather natural result because the dynamics
of the wave packet centroids is governed only by theequation of motion of AMD which has a classical form.
I t should be reminded that we are treating the
AMD wave functions and the calculation of observabIes is made for these wave functions. For example, we can consider the occupation probability of thesingle-particle level for the harmonic oscillator mean
field case. Assuming that the wave packet centroids
obey the classical canonical statistics with the temperature Te, the occupation probability P~ (Te) for the nthlevel is calculated numerically (or analytically for thecase of distinguishable particles) by taking account of
the spread of wave packets. On the other hand , theusual quantum relation of the occupation probability
is denoted by Pn (T) as a function of the temperature
T. By the calculation it is proved that P~(Tc) = Pn(T)is satisfied for any n if we relate Tc and T by a certain relation. This result just means that the statistical property of wave packets is quantum and there isnothing to be complained about the AMD descriptionof the statistical property of the internal motion of nuclei. It is emphasized that the temperature Tc of theclassical statistics of wave packet centroids is different
from the temperature T of the quantum statistics ofwave packets.
However, the statistical property of AMD for the
nucleon-emission process is classical because it is described only by the motion of wave packet centroid.
This defect of AMD is clearly proved by the calculationof the liquid-gas phase equilibrium realized for a manynucleon system confined in a large potential wall. In
Fig. 1, we show the completely classical relation be-

30

tween the excitation energy of the liquid nucleus andthe temperature of the system which is calculated fromthe kinetic energy of the gas nucleons.
o ~---'~---r----'-----~--~
,

?

-2

Volkov

Aliq = 14

¢
-4

~I
-8

r
T2/12
3T
AMD-MF 0
AMD 0-1 0 L - -_ _---r.____.....L._ _ _ _...&...._ _ _ _........_ _
o
2
4
6
8

~

10

T [MeV]
Fig. 1. The statistical property of the excited nucleus calculated with the usual AMD and the AMD-MF. Linesof (E/A)liq = 3T+const . and T2 /(12MeV)+const. are
drawn for the comparison.

The reason of the above result is that the nucleon
cannot go out of the nucleus unless the centroid can,while the high momentum component should be allowed to go out in the exact quantum description.
In order to solve this problem, we propose to introduce a new stochastic process into AMD by giving
the momentum fluctuation to the wave packet according to its momentum distribution. This extension enables the wave packet to split stochastically into several parts and therefore the high momentum part cango out of the nucleus. This extended AMD is called
AMD-MF (AMD with momentum fluctuation). The
calculated statistical property of AMD- MF for the
nucleon-emission process is also shown in Fig. 1, which
proves that the quantum statistical property for the
nucleon-emission process has been recovered by the
new stochastic process.
References
1) A. Ohnishi and J. Randrup: Nucl. Phys., A565, 474(1993).
2) J. Schnack and H. Feldmeier: preprint GSI-95-34(1995).
3) A . Ono, H. Horiuchi, Toshiki Maruyama, and A.
Ohnishi: Prog. Theor. Phys. , 87, 1185 (1992).

RIKEN Accel. Prog. Rep. 29 (1996)

Antisymmetrized Molecular Dynamics with
Stochastic Incorporation of Vlasov Equation
A. Ono and H. Horiuchi
antisymmetrized molecular dynamics , wave packet, Vlasov equation,
heavy-ion reaction, fragmentation, 40Ca + 40Ca at 35 MeV/nucleon.
An important fact which we learned in the studyof the statistical property of AMD is that the originof the problem is the simple single-particle motion,
and we have improved the nucleon-emission process
by taking account of the splitting of the wave packet
according to its momentum width in AMD-MF (AMDwith momentum fluctuation). This extension of AMD
should be generalized for the application to nuclear reactions because the spreading and/or the splitting ofwave packets is important in various processes as wellas the nucleon-emission process.
The general method , called AMD-V (AMD with
Vlasov equation), is formulated as follows. At eachtime to, the time evolution of each Gaussian wave
packet with the physical coordinate being its centroid
is calculated with the Vlasov equation which is a semiclassical approximation of time-dependent HartreeFock (TDHF) equation and therefore does not have
any restriction on the wave packet shape. The wave
packet at to + 8t which has diffused to some directions
in phase space is represented by a sum of Gaussian
wave packets with the same width as that of the Gaussian wave packet at to and then one of these Gaussian
wave packets is chosen stochastically according to its
weight. In other words , a stochastic displacement isgiven to the wave packet centroid so that the ensembleaveraged time evolution of the one-body distributionfunction is equivalent to the solution of Vlasov equation for the diffusing directions.
As explained above , AMD-V has introduced thestochastic branching process. It should be emphasizedthat the future time evolution of each branch is independent of other branches. This situation corresponds
to the linear combination of wave functions of channels
in truely quantum description. On this point , AMD-V
is different from TDHF (or Vlasov) equation though
they are equivalent for the instantaneous time evolution of one-body distribution function. Especially,
the fluctuation of the mean field among branches (orchannels) is described in AMD-V, which enables thedescription of the fragmentation.
In order to see the important effects of the incorporation of Vlasov equation in heavy-ion collisions, we havecalculated 40Ca + 40Ca reaction at 35 MeV/nucleon
with AMD and AMD-V using Fujitsu VPP500 of
RIKEN. In the calculation of AMD, most events haveturned out to be binary with very excited (E* / A rv 5
MeV) projectile-like and target-like fragments whose
decay is very slow. The yield of light intermediate

mass fragments (IMFs) is very small. Few a particles(0.2 rv 0.3 per event) are produced in the dynamical
stage, while the yield of protons is overestimated. On
the other hand, in AMD-V many IMFs are produced in
the dynamical stage of reaction (t ;S 200 fm/c). Their
excitation energies are already small (E* /A rv 2 MeV)
and therefore the effect of the statistical decay is notimportant. The multiplicity of dynamical a particles isabout 2- 3 and the overestimation of proton yield is not
so large. As shown in Fig. 1, we have obtained very
good reproduction of the data of charge distribution
as well as other features of the fragmentation. These
data have never been reproduced so well by any othermicroscopic models and statistical models.

102

40Ca + 40Ca
10
~

:2

E/A = 35 MeV
b<7 fm

1

AMD
Exp.

¢

10°

Q.

+=
"S
~

10-1
10-2
102

40Ca + 40Ca

E/A = 35 MeV
b<7fm

10 1
~

:2

AMD-V
Exp.

¢

10°

g"S
~

10-1
10-2
10-3

0

5

10

15

20

25

30

Z
Fig. 1. Charge distribution of fragments produced in
40Ca + 40Ca collisions at 35 MeV/nucleon calculatedwith AMD (upper) and AMD-V (lower). Experimental
filter has been applied.

31

RIKEN Accel. Prog. Rep. 29 (1996)

Collisional Damping and the Temperature Dependenceof Nuclear Dissipation
H. Hofmann,* F. A. Ivanyuk,** and S. Yamaji[large scale collective motion, linear resp.::>nse theory.]
To date the nature of nuclear dissipation is still anunresolved problem. For isoscalar modes at finite excitations the best information available at present comesfrom fission experiments, when comparing the decayrate of fission with the ones for emission of light particles or gamma rays. Nowadays it seems not only
possible to deduce numbers for the effective damping rate TJ at the barrier,!) but to gain information
about its temperature dependence. 2 ) In our notation
TJ = ,/(2) M I C I), with" M, C being the coefficientsfor friction, inertia and stiffness. The authors of Ref.2
find an TJ which increases markedly with T , at small tomoderately large values of the temperature.
Such behavior is hard to understand, neither on thebasis of two body viscosity nor on the wall formula. 3 ) In
the first case friction should decrease with T like T- 2 ,in the second it would practically stay constant. In
principle, the other two transport coefficients appearing in TJ, namely M and C, must be expected to changewith temperature, too. But such dependence will be
weak, as long as they are evaluated within the macroscopic models. 3 ) Therefore, the observed increase of 'T]
with T shows us strong evidence for the necessity fora microscopic theory.
In this report we want to concentrate on temperatures where the influence of self-consistency on friction
is small. 4) Then we may apply the zero frequency limit,
which gives

the imaginary part of the self-energy does not increaseindefinitely when the excitations get away from theFermi surface.
In Fig. 1 we show the temperature dependence offriction. They have been obtained for a system of 138
particles by using an infinitely deep square well for the
single particle potential. At low temperatures, we see
a marked increase. At higher temperatures, we see,(0) to reach some maximal value of the same order ofmagnitude as the one of the wall formula, shown hereby the horizontal line.

.c:

300

. ~ 200
<::>
'<"--

100
0

300

.c:
200
~
~
<"--

100

c = 20 MeV(1)0denoting by Fj k the matrix elements of P in the mean
field. Here, n(x) is the Fermi function determining theoccupation of the single particle levels. The (!k (w) represents the distribution of the single particle strength
over more complicated states and can be written as

ed w ) =r(w , T)(liw -

ek -E'(w, T»2 +(r('2,T)) 2(2)

For r (w, T) the following form has been used1(liw - p.)2 + 7r 2 T2r ( w, T) = - ----'-----:;:---'-----ro 1 + ~ [(nw - p.)2 + 7r 2 T2](3)with J.l being the chemical potential. The factor 1Ir 0
represents the strength of the "collisions". The cutoff parameter c allows one to account for the fact that
Physik-Department der Technischen Universitiit, Germany
Institute for Nuclear Research of the Ukrainian Academy,
Russia

32

0

4

6

8

10

T[MeV)

Fig. 1. The friction coefficient ,(0) as a function of T.
Comparing the upper and lower figures, we observe a
pronounced sensitivity of the T-dependence of friCtion
on the cut-off par'a meter c. Within the mere "relaxation time approximation", i.e. for c ~ 00, friction
drops like T- 2 , as expected for hydrodynamic modes.
References
1) D. Hilscher and H. Rossner: Ann. Phys. Fr., 17, 471(1992).
2) P. Paul and M. Thoennessen: Ann. Rev. Part. Nucl.
Sci. , 44, 65 (1994).
3) W. J. Swiatecki: Nucl. Phys. , A574, 233c (1994).
4) S. Yamaji et al.: ibid. , A475 , 487 (1988).

RIKEN Accel. Prog. Rep. 29 (1996)

Dissipative Dynamics of Fission Studied with Three-Dimensional
Langevin Equation
T. Wada, S. Yamaji, and Y. Abe[Fission, Langevin equation, mass asymmetry, prescission neutron, fragment kinetic energy.]
Fission phenomenon induced by heavy ions provides
a good field to study nuclear dissipative dynamics inhigh excitation. The collective fissioning mode interacts frequently with the thermalized nucleons. We canconsider it as a Brownian particle interacting with aheat bath of nucleons. Langevin equation is expected
to be useful for a phenomenological description.
As is well known, fission is a multi-dimensional phenomenon: a number of macroscopic collective degrees
of freedom have to be taken into account, e.g., a distance between future fragments , fragment deformation, necking, mass asymmetry, etc. In particular,
the mass-asymmetric degree of freedom is very important because the fragment mass distribution can bemeasured directly. To consider the mass-asymmetricdegree of freedom, we have to treat at least threedimensional collective space, which requires a lot ofcomputations. Recent rapid increase of the computer
power has enabled us to extend the Langevin approachto the three-dimensional case. I)
In a previous study, two-dimensional Langevin equation was applied to the symmetric fission of 2ooPb. 2)
Including the particle evaporation in the continuous
limit, we calculated the prescission multiplicities ofneutrons as well as the kinetic energy distribution offission fragments at the same time. The calculatedprescission neutron multiplicity (v pre ) and the meanvalue of the fragment kinetic energy (TKE) coincidewith the experimental ones. 3 ) The calculated varianceof the kinetic energy (aT K E) , however, is too small
to reproduce the experiment. The small aT K E may
indicate that the two-dimensional description of thenuclear shape is not sufficient to describe all possible
scission configurations.
In view of the importance of the mass-asymmetricdegree of freedom, three-dimensional calculation has
been performed for the same system including the
mass-asymmetric degree of freedom. For this case,we adopt the shape parametrization by Maruhn and
Greiner. 4 ) The neck parameter c is fixed to 0.4 in thepresent calculation. We have treated Zo (distance between the two potential centers), a (mass asymmetry parameter), and 8 (fragment deformation parameter) as 3 collective parameters to be described by theLangevin equation.
The results of two- and three-dimensional calculations with one-body (wall-and-window) friction is
given in Table 1 for E* = 195.8 MeV and for several values of the spin of the compound nucleus (f).
The mean values of the fragment kinetic energy inthe three-dimehsional case are slightly smaller thanthe corresponding two-dimensional ones. Three-dimensional aT K E 's are larger than the corresponding
two-dimensional ones by about 20%, which turns out
to be compatible with the experiment. 3) One should
notice that the prescission neutron multiplicity differs
very little between two- and three-dimensional calculations , which means that the time scale of fission does
not change in the two cases. The effect of inclusionof the mass asymmetric degree of freedom is that it
acts to reduce the mean value of the fragment kinetic
energy compared with that in symmetric fission andacts to increase the variance by allowing more flexible
scission configurations.
The computer work has been performed on FUJITSU VPP500, RIKEN.
Table 1. Comparison between the results of two- andthree-dimensional Langevin calculations.
2DIM

3D 1M
f

(jTKE

TKE

(Ii)

(MeV)
13.2
14.1
15.4

(MeV)
142.6
142.8
143.2

30
50
70

V pre

(jTKE

TKE

V pre

8.06
6.97
5.74

(MeV)
10.7
11.6
12.5

(MeV)
147.2
148.5
150.0

7.96
6.74
5.45

References
1) T. Wada: Proc. Tours Symp. on Nuel. Phys . II, World
Scientific, Singapore, p. 470 (1995).
2) T. Wada, Y. Abe, and N. Carjan: Phys. Rev. Lett., 10,3538 (1993).
3) D. J. Hinde et al.: Nucl. Phys., A452, 550 (1986); D.
J. Hinde et al.: Phys. Rev., C45, 1229 (1992).
4) J. Maruhn and W. Greiner: Z. Phys., 251, 431 (1972);
K. Sato et al.: ibid., A288, 383 (1978).

33

RIKEN Accel. Prog. Rep. 29 (1996)

Quenching of the Coulomb Sum Value
H. Kurasawa* and T. Suzuki[NUCLEAR STRUCTURE electron scattering, Coulomb sum.]Sum rules are one of the most important touchstonesof nuclear models. If experiments show the sum rules
not to be satisfied, it means a breakdown of the model,
and new models or new degrees of freedom are required. For example, the sum of the Gamow-Teller
strength should be given by rv (N - Z) , when nucleonic degrees of freedom only are taken into account.
In a (p,n) reaction, however, the quenching of the sumvalue has been observed. This fact implies a contribution from other degrees of freedom like ~ ' s. For thesum of the photo-absorption strength, on the other
hand, the nuclear current provides the sum rule value
rv N Z / A. Experiments have shown, however, enhancement of the strength , which indicates the existence ofthe meson exchange current in nuclei.
In electron scattering, the sum rule on the longitudinal response function is known, which is called the
Coulomb sum rule. This is derived for a nonrelativistic nucleon system. Experiments on the sum rule havebeen performed at Saclay,1 ,2) Bates,3) and SLAC ,4)and shown that the sum rule value is quenched by
20- 50% in medium heavy and heavy nuclei.
We have studied what kind of new degrees of freedom is required in the electron scattering. 5 ) The
Coulomb sum value has been calculated in nonrelativistic and relativistic models. It has been shown thatparticle-hole correlations within the Fermi sea explain

Department of Physics, Faculty of Science, Chiba University

34

a part of the quenching observed in medium heavy
and heavy nuclei , but they are not enough to explain
the data both in relativistic and nonrelativistic models. If we include antinucleon degrees of freedom in theparticle-hole correlations, the relativistic model can reproduce the available data. The relationship among
the antinucleon's effects, modification of the nucleon
size and the effective mass of mesons is also discussed.
New experimental data on the Coulomb sum are required at the momentum transfer between 0.6 and 1
Ge V, in order to confirm the prediction of the present
relativistic model.

References
1) P. Barreau et al.: Nucl. Phys. , A402 , 515 (1983) ; Z. E.
Meziani et al.: Phys. Rev. Lett. , 52 , 2130 (1984) ; Z. E.
Meziani et al.: ibid., 54, 1233 (1985) .
2) A. Zghiche et al.: Nucl. Phys. , A572 , 513 (1994).
3) M. Deady et al.: Phys. Rev. , C33, 1897 (1986) ; C.
Blatchley et al.: ibid. , C34, 1243 (1986); T. C. Yates etal.: Phys. · Lett. , B312, 382 (1993) .
4) J. P. Chen et al.: Phys. Rev. Lett. , 66, 1283 (1991) ; Z.
E. Meziani et al.: ibi d. , 69, 41 (1992).
5) H. Kurasawa and T . Suzuki: Proc. , the Korea-Japan
Joint Symp. on Recent Developement of Nuclear Study
using Electron and Photon Beams, I-Tong Cheon (ed.),Global Publication Services, Singapore, p. 39 (1995) .

RIKEN Accel. Prog. Rep. 29 (1996)

Symmetry Energy at Subnuclear Densities and the Layer of
Non-Spherical Nuclei in Neutron Star Crusts
K. Oyamatsu, K. Sumiyoshi, Y. S. Mochizuki, and H. Toki
[relativistic field theory, equation of state, neutron stars, unstable nuclei, neutron skins.]
The structure of neutron-star crusts is one of themost important part of neutron stars because all we
can observe from the earth are limited to phenomena which occur at neutron-star surfaces (crusts). The
crustal matter itself is also interesting because of its extreme neutron richness which can never be produced inlaboratories. Furthermore, one of the present authors(K.O.) showed that the stable nuclear shape in the inner crust matter is not necessarily spherical, and thatit should change from sphere, to cylinder, slab, cylindrical hole and spherical hole with increase of density
before the nuclei finally dissolve into uniform matter.1)
These exotic nuclear shapes are now being investigatedfrom the viewpoints of their implications in the structure and evolution of neutron stars. 2 - 6 )Recently, Sumiyoshi, Oyamatsu and Toki 7 ) performed the Thomas-Fermi calculation of the crustal
matter with an equation of state (EOS) in the relativistic Brueckner Hartree-Fock (RBHF) theory and foundthat the layer of the non-spherical nuclei is much thinner than those calculated with non-relativistic EOS's.
In Fig. 1, we compare the RBHF results with a nonrelativistic result with model IV in Ref. 1 (hereafterreferred to as oya4). In these two models, the energies due to the gradients of local nucleon densities arenearly the same. Therefore, this discrepancy is expected to stem from the bulk properties of the EOS.
We note here that the shell effects are too small at thedensities of interest to change results of the semiclassical calculations. 8)

oya4
RBHF

oya5
oya6
0.04

0.05

0.06

0.07

0.08

0.09

0.10

3
nb (fm- )Fig. 1. The density region of the non-spherical nuclei
calculated with various models.

In the present study, we focus on the effects due tothe symmetry energy and perform the Thomas-Fermi
calculation of the inner crust matter with two energy
density functionals, oya5 and oya6, which are the sameas oya4 except for the density dependence of the symmetry energy. The symmetry energy of oya5, having
the same value as oya4 at nuclear density, is a nearlylinear function of density as those of most of relativistic
EOS's are. On the other hand, oya6 has similar density dependence to oya4 but its value is much smaller(by 13%). As shown in Fig. 1, the density region of
the non-spherical nuclei is quite sensitive to the density dependence of the symmetry energy (oya5), rather
than to the value of the symmetry energy at saturation density (oya6). This implies that properties ofthe matter in the inner crust with extreme neutronrichness should be investigated with due considerationof the symmetry energy at subnuclear densities. We
also note that the density dependence at subnuclear
densities affects "its high density-part of the EOS whichis crucially important to determine bulk properties ofneutron stars, such as mass and size. We may extract
some information from careful investigations on properties of unstable nuclei, especially from neutron skins,
and this line of study is now being carried out.

References
1) K. Oyamatsu: Nucl. Phys., A56l, 431 (1993).
2) Y. Mochizuki and T. Izuyama: Astrophys. J., 440, 263(1995).
3) G. Lazzari and F. V. De Blasio: Nuovo Cim., Al07,
1423 (1994).
4) G. Lazzari and F . V. De Blasio: Z. Phys., A350, 117(1994) .
5) F . V . De Blassio and G. Lazzari: Phys. Rev., C52, 418(1995).
6) G. Lazzari and F. V. De Blasio: Z. Phys., A353, 13(1995).
7) K. Sumiyoshi et al.: Nucl. Phys ., A595, 327 (1995) .
8) K. Oyamatsu and M. Yamada: ibid., A578 , 181 (1994).

35

RIKEN Accel. Prog. Rep. 29 (1996)

Braking Index Changes from Neutron Star Glitches
Y. S. Mochizuki[Neutron stars.]Pulsars are rotating neutron stars with very strong
magnetic fields.
We know their rotational states
through observing pulsating radio signals from them.
Pulsars usually undergo a slowdown according to asimple power law, ne = -k D~, where De is the angular velocity of the observed crust of a pulsar, k is aconstant , and n is called the braking index. I;r: pr~n­ciple, the braking index is defined as n = DcDcl D~.
For magnetic dipole braking, n = 3. Measured index
values so far include n = 2.51 for the Crab pulsar,n = 2.84 for PSR B1509-58, and n = 2.01 for PSR
B0540-69. It has been reported recently, however, thatsome pulsars have abnormal braking indices; the index
of PSR B1757-24 has decreased from rv 41 to rv 22 inless than 1 year. A possible explanation on the anomalous braking indices is based on glitches.
Glitches are unpredictable sudden spinups of pulsars. The size of a glitch is defined as ~Dc/Dc , where~Dc is a change in Dc brought about by a glitch. In
the Vela pulsar, for example, the glitch size is of theorder of 10- 6 . After a glitch, the increased angular velocity decays towards almost the extrapolation of the
preglitch values with a larger deceleration rate than before. Therefore, in the postglitch relaxation phase, thebraking index can become large and change in the timescales of the relaxation. Although glitches have notbeen observed in PSR B1757-24, it possibly glitched
before the beginning of observation, and may be in its
recovery state from the glitche.
The physical origin of glitches is a long standing
open problem since a glitch was first observed in Velain 1969, whereas the postglitch relaxation has been
explained by means of the vortex creep model. 1) The
vortex creep model describes coupling states between
the observed neutron star crust and neutron superfluid, which is rotating at Ds in the star interior. In
this model, the two components are assumed to be
decoupled at the time of a glitch, and the postglitch
relaxation is regarded as a recoupling process between
the two. Here, the braking index changes from glitches
were simulated under a reasonable range of neutronstar models, glitch sizes, and the vortex creep model
parameters. The results were applied to the case observed in PSR B1757-24.
Figure 1 shows the braking index changes corresponding to various glitch sizes for the neutron starmodel constructed by stiff (PS) equation of state andthe vortex creep model parameter WeT = Ds - Dc =0.1 rad 8- 1 . We see that a larger glitch produces alarger maximum of the braking index.
N ow we are going to discuss about the case of PSR
36

PS Star. UlCf - O.1 rad s"tlIIJ~=IO"- tlIIJ~=IO"-·- tlIIJ~=IO·'

oL-~~~~~~~C=~~o3"
5time after a glitch (yrs)Fig. 1. Evolution curves of braking index after a glitch.

B1757-24. The observation of this pulsar has started in
January 1990. Figure 2 shows the observed change ofthe braking index2 ) and its fitting by the above modelof the glitch size 10- 6 . Since PSR B1757-24 and the
Vela pulsar are of almost the same age, the size 10- 6
is also preferable for PSR B1757-24. From Fig. 2 we
see that the observed index decrease can be explained
as the interglitch behavior, and a glitch of rv 10- 6 size
would have 'taken place about 2 years before the beginning of the observation.
time after a glitch (yrs).o°;....----;....-.;---,;....-,.----;....--r----,
x

~

Ii

tlIIJ~=IO"

30

~

i

observation

PSSw'(&)cr=O. 1 rads· 1,

1.

20

...

..........
't, : 6.2'1"" """ :;"""-

SWl= 1988.34

A.D.

Fig. 2. Best fitting for observed braking indices of PSR
B1757-24.

In the vortex creep model, we can roughly estimate
the glitch interval as 79 = 10 - 2 /1n e l = 6.2 years for
PSR B1757-24 under the assumption that it experiences Vela-like glitches. If PSR B1757-24 is really aglitching pulsar, this means that it will glitch again
around 1994. Based on the above estimation by the author, the timing behavior of PSR B1757-24 was further
analyzed, and it was recently confirmed that the pulsar actually had glitched in February 1994. 3 ) Namely,
the abnormal braking indices are significant as an indicator of glitching pulsars.
References
1) M. A. Alpar et al.: Astrophys. J., 409, 345 (1993).
2) V. M. Kaspi: private communication.
3) A. G. Lyne et al.: in preparation (1995).

RIKEN Accel. Prog. Rep. 29 (1996)

Exotic Nuclear Deformation in the Neutron Star Crusts
and the Origin of Glitches
Y. S. Mochizuki, K. Oyamatsu, and T. Izuyama[N eutron stars, Coulomb lattice potential, Nuclear fusion.]
The inner crust of a neutron star consists of the lattice of neutron rich nuclei and the superfiuid neutrons.
These are imbedded in the degenerate Dirac electrongas. Since the neutron superfiuid is rotating, there
exist many quantized vortices. The vortex lines are
expected to be nearly parallel to the axis of rotation.
Each superfiuid vortex line possesses a normal fluid
core over a distance (, the coherence length of the superfiuid. In the vortex core the pairing energy of theneutron Cooper pair is lost. To simplify, we assume
that the Cooper pair formation is prohibited in nuclei.
Then clearly the most energetic position of a vortex
core is achieved by maximum overlap of a vortex andnuclei. Hence the vortex line is expected to be pinned
along a line of nuclei.
In the major part of the inner crust the nuclei are
expected to be spherical. In the vicinity of the stellar core, however, the nuclear materials in the crust
may take exotic forms. These are the lattice of nuclear rods and the multi-layer of plate-like nuclear
matter .1 ,2) This was derived from energetic considerations; the stable nuclear shape is determined by minimizing W s + We, where W s is the surface energy andWe the Coulomb energy. This argument holds for thevortex free region.
The nuclear shapes inside and in the vicinity ofthe vortex core lines are accomplished by minimizing(Ws + We) + [the pairing energy in the neutron superfiuid]. In the inner crust there exists a region where
the pairing energy plays an important role in this minimization and hence the nuclear materials pinning thevortex core line may not be a series of spherical nuclei. A novel nuclear material may be constructed byabsorbing some nuclei into the vortex core. In thisway the pairing energy will be gained at the expenseof the Coulomb energy. From the energetic point ofview, we have confirmed 3) that a vortex core line can
induce a nuclear rod along itself (Fig. 1) . Significantly,
this pinning-induced nuclear rod will strongly trap thevortex line. This self-trapping may be a crucial mechanism for the pulsar glitches, i.e., sudden spin-ups ofneutron stars.3) The nuclear rod formation requires a
nuclear fusion.

How high is the Coulomb energy barrier? Here, weinvestigated the Coulomb barrier for the initiation of
the fusion , in which one of the nuclei is absorbed fromthe neighborhood into the vortex core. We consideled
cubic boxes made up of many (up to rv 103) nuclei withperiodic boundary conditions. The electrostatic interaction is considered by Fourier analysis. We found thatthe barrier is definitely less than 3.1 MeV. Note that
the Coulomb energy of the nearest neighbor nuclear
pair is 80 Me V if we aaopt 30 fm for the nuclear separation and 40 for the proton number of a nucleus, thesuggested value in previous papers. There are two reasons for the dramatic reduction of the barrier. The firstreason is the electron screening. The second is a smallvalue, 22 , of the proton number in a nucleus adopted
here, which is a recent result from the equation of statebased on relativistic Brueckner-Hartree-Fock theory.4)
When the consider~d nucleus is absorbed into thevortex core, the other nuclei were assumed to be fixedat their lattice sites. Actually the nuclear positions
must be relaxed. We therefore expect a substantiallylower Coulomb barrier than 3.1 MeV.

...... ...... .. ·• ·1··••·
Nuclear rod

Vortex core line

-'~~-

:.~
•

.:

. -.

Nucleus••••• ••••

Fig. 1. A naive sketch of deformation from spherical to
rod-like nuclear matter, induced by a vortex line.

References
1) K. Oyamatsu and M. Yamada: Nucl.
,,Phys., ·A578, 181(1994).
2) C. J. Pethick et al.: ibid. , A584, 675 (1995),
3) Y. Mochizuki and T. Izuyama: Astrophys. J., 440, 263(1995).
4) K. Sumiyoshi et al.: Nucl. Phys., A595 , 327 (1995).

37

RIKEN Accel. Prog. Rep. 29 (1996)

A Study of Collision Frequency and Particle Density in
Ultrarelativistic Nuclear Collisions by
an Event Generator URASiMA
S. Date, K. Kumagai,* O. Miyamura, H. Sumiyoshi, and X-Z. Zhang**[high energy reaction, quark-gluon plasma, event generator.]

It is a basic problem for creating QGP in laboratories to what extent nuclear matter is compressed andwhether or not the thermalization is accomplished inultrarelativistic nucleus-nucleus (A-A) collisions. To
answer the problem, we have studied local collision frequencies of hadrons produced in ultrarelativistic A-A
collisions by employing an event generator URASiMA.
It turns out that a thermalized high density local system is achievable in the CERN-SPS energy region although its size is not always large.
The event generator URASiMA describes A-A collisions in a conventional hadronic level employing themulti-chain model (MCM)l) for generation of multiparticle final states. The generator traces trajectories
of particles which are treated as straight lines between
interaction points in full 1 + 3 dimensioal space-time.
Interactions between two particles are treated as pointlike so that the problem of ambiguous time ordering is
avoided.
The produced particles suffer secondary cascade collisions after the formation time in their hadronic environment. URASiMA takes into consideration fullgenerations of cascade collisions although interaction
channels are limitted, at the moment, to inelastic andelastic nucleon-nucleon (N-N) , 7r-N interactions, andelastic 7r-7r interaction via P meson. The inelastic 7r-N
interaction is included as a channel 7r N ---t 7r ~ ---t 7r7r N.
The validity of the model has been checked by comparing the output of URASiMA with several experimental data on the global quantities and, newly forthis time, with the experimental data on Sulphur +Nucleus collisions at 200 GeV /nucleon. 2 )As the process of a collision evolves, decelerated nucleons and produced hadrons form a collision complex.
We may estimate the nucleon and pion density in a
sphere of volume V located in the center of the complex from the local collision frequency as

PN =Department of Physics, Hiroshima University
China Institute of Atomic Energy

38

P7r =

Note that we are counting only the number of theseparticles which are involved in collisions and contributeto thermalization of the system.
Figure shows the dependence of the particle number
densi ty on the stopping power of nuclei and on the
nuclear mass numbers. Refer to Ref. 3 for details.
(a)
-..

(b)

Nucleon

0 .5

I

....

a: = 1a: = 3

0.4

/

'en
~
Q)

0.3

Q)

1l....
L.

Pb

....
Q)

..c:

r-

,~

p.,

III

-

0.2

(IS

ph
,II(

'-

>.

t:l

05

'1

M

E
.:=.

Pion

/:'

Ag

S

-

-

0.4

0.3

-

0.2

-

0.1

Ag
a'

0.1

'-

S

tID

:E

0.0

.1
10

50

100

500 10

50

100

0.0
500

Target Mass Number
Fig. 1. Target mass number dependence of the highest (a)nucleon- and (b) pion-density inside the central sphere
for a = 1 (solid curve) and a = 3 (dashed curve).

References
1) K. Kinoshita, A. Minaka, and H. Sumiyoshi: Prog.
Theor. Phys., 61 , 165 (1979); ibid., 63, 928 (1980).
2) WA80 Collab., R. Albrecht et al.: Z. Phys ., C55, 539(1992).
3) S. Date, K. Kumagai, O. Miyamura, H. Sumiyoshi, and
X-Z. Zhang: l. Phys. Soc. lpn., 64, 766 (1995).

RIKEN Accel. Prog. Rep. 29 (1996)

Gluon Distribution Function using Bag Model and
QeD Sum Rule
H. Kitagawa[polarized gluon, bag model, QCD sum rule.]
Deep inelastic scattering experiments using high energy leptons have disclosed the structure of hadrons,
which are composed of "quarks" and "gluons". Most of
the theoretical models of hadrons assume that hadrons
are composed only of quarks. Experimental data, however, have shown that the quarks do not carryall of
the momentum of hadron, then gluons are pointed out
to play an important role. One of the main purposes of
the RHIC-SPIN project (polarized proton-proton collider) is to investigate the polarization of gluons in the
proton, and to give an answer to the "proton spin problem".
Bag model is one of the effective tools to study theproperties of nucleons. Nucleon is made of three quarks
inside the bag, which is considered to represent thegluon condensation. MIT bag model is the simplest
one, and is employed here. Results of calculations areshown in Fig. 1. In this model, perturbative gluons are
obtained by the Maxwell equation with the source termof quarks. Non-perturbative part, "bag", contributes
to them indirectly through quarks. Bag model, hence,is not suitable for the discussion of absolute valuesof observables, though it is useful to study the global
structure, i.e. x-distribution.
QCD sum rule is a useful method to evaluate absolute values. This is complementary to the result ofbag models, and is applied to the gluon "spin" contribution, i.e. the expectation value of gluon distribution,or the second moment of distribution:(5c) =

10' x t!.G(x)dx.

(1)

Belyaev and Blok applied this method to the spinunpolarized gluon in Ref. 1, which is followed here.
Second moments of quark and gluon appear in the response of constant external fields, which are introducedby the following lagrangian terms,

f:l.c q = -i¢DJ-L"Yv¢SJ-LV
f:l.c c = -OJ-L >"O>..vS 1J-LV

(2)
(3)

where ¢ and 0 represent the quark and gluon respectively, and Sand Sl are the tensor external fields.
Their forms are determined by the operator productexpansion (OPE). In the spin-polarized case, following
lagrangian terms are derived by OPE.

0.00"'.cpol. -

U

-0.02

><

q

-

·A.D

- ~'f/,./,.SJ-LV

J-L"Ys'Yv'f/ pol.

f:l.cPol. = _ (1/2)c >..po- 0CC5' -0.04

J-L

po-

0 >..v SlJ-Lv
pol.'

(4)
(5)

<I

><

Second moments of the distributions of the polarized
quark and polarized gluon are obtained using the above
lagrangian terms. Calculations are now in progress.

-0.06

-0.08
0.2

0.4

0 .8

0 .8

References
Fig. 1. Polarized gluon fraction calculated using the MIT
bag model.

1) V. M. Belyaev and B. Yu. Blok: Z. Phys., C30, 279(1986).

39

RIKEN Accel. Prog. Rep. 29 (1996)

Lattice-QCD Calculations Using VPP500
S. Kim and S. Ohta
[lattice quantum chromodynamics, parallel computer.]
We are calculating the mass of light hadrons inquenched lattice quantum chromodynamics (QCD)
with staggered quarks. 1) The new vector-parallel supercomputer of RIKEN,2) VPP500, allows us to dosuch a calculation on the largest-ever lattice size of48 3 x 64 at the finest-ever lattice spacing of a-I
4Ge V (or equivalently the inverse-squared lattice coupling of (3 = 61 g2 = 6.5). The physical lattice volume of about (2.4 fm)3 is large enough for extrapolation to remove the errors from finite volume. The
lattice spacing is fine enough for extrapolation to remove such a discretization artifact like the flavor symmetry breaking. We are also able to use such lightquark mass like mq = 0.00125a- 1
5 MeV, i.e. we
no longer have to make extrapolation from very heavy
values like mq
100 Me V. Being free from these systematic errors simultaneously for the first time, we areready to study another type of systematic error arising from the quenched approximation itself. There aresuggestions 3) and possible evidence 4) that the chiral(mq ---? 0) limit of quenched QCD differs from that offull QCD in regard of the divergent "quenched chirallog" term, In m q . In the latter works,4) however, theformer three types of systematic error were studied separately. In contrast the present work simultaneously
addresses all of them. Also in the current study thechiral limit should be approached more reliably than
before since the flavor symmetry violation is smaller.
Our preliminary results using 50 gauge configurations are summarized in the Edinburgh plot in Fig.
1. In contrast to earlier studies, all the points, except for the left-most point for the lightest quark
mass, lie below the guiding lines. This means thatthe ground-state nucleon is less squeezed on the current lattice than before. At the lightest quark massof mq = 0.00125, we now see the ratio mnlmp as low
as0.3. This suggests that our lattice is big enougheven down to such light quark mass. Thus pushing thequark mass even smaller and reaching the region wherem7[ Imp ~ 0.2 and mn ~ 0.04 are now viable. Extrapolation to small mq will soon be unnecessary. Also
the current result shows approximate flavor symmetry
restoration: the mass of Nambu-mode pion and thatof non-Nambu-mode pions agree with each other. All
these attractive features of the current results suggestthat the chiral limit of our data will be more interesting. However, we think that the investigation on the

1.6

~
1.4

f"V

J:

Q.

f

8

'"E'z"

1.2

1.0

f"V

o

0.2

0.4

0.6

0.8

1.2

f"V

f"V

40

Fig. 1. Edinburgh plot at (3 = 6.5 on 48 3 x 64 lattice forquark mass mq = 0.01, 0.005, 0.0025 and 0.00125. The
two circles are the experimental point (left) and naive
quark model prediction (right).

quenched chiral log in the pion mass and chiral condensate requires a still higher statistics of at least 100
gauge configurations and perhaps more. We alreadygathered 100 configurations and their full analysis isunder way.
Using the same supercomputer, SO is also involvedin the development of the "Self-Test Monte Carlo"
method for a reliable frame work of numerical Monte
Carlo calculations in general, and SK is involved inprojects on the over-improved cooling method and 3D
Thirring model respectively concerning some featuresof lattice QCD.
References
1) S. Kim and S. Ohta: in Proc. "Lattice'95," Nucl. Phys.
B, (Proc. Suppl.), to be published.
2) S. Kim and S. Ohta: in Proc. "Lattice'94," Nucl. Phys.
B, (Proc. Suppl.) , 42, 920 (1995).
3) S. R. Sharpe: Phys. Rev., D46, 3146 (1992); C. W.
Bernard and M. F. L. Golterman: ibid., D46, 853(1992).
4) S. Kim and D. K. Sinclair: Phys. Rev., D48, 4408
(1993); Nucl. Phys. B (Proc. Suppl.), 34, 347 (1994);
Phys. Rev. , D52, R2614 (1995).

RIKEN Accel. Prog. Rep. 29 (1996)

Effective Potential Formalism for Dynamical Chiral-Symmetry
Breaking in the Dual Ginzburg-Landau Theory
S. U misedo,* H. Suganuma, ** and H. Toki
[QCD , color confinement, chiral symmetry, effective potential, monopole condensation.]
Recent progress in the lattice gauge theoryl) clarifies the central role of QCD-monopole condensation2- S)
in color confinement, which was firstly conjectured
by Nambu. 2 ) The important correlation between
QCD-monopole condensation and dynamical chiralsymmetry breaking (DXSB) was firstly pointed out by
Suganuma-Sasaki-Toki 2 ) solving the Schwmger-Dyson(SD) equation in the Dual Ginzburg-Landau (DGL)
theory, and was discovered by Miyamura also in thelattice QCD. 6 )We study DXSB in the DGL theory using the effective potential formalism instead of the SD equation
to extract the contribution of confinement to DXSB directly. Within the ladder approximation, the SD equation is generated from the effective potential f eff [S] up
to the two-loop diagram by imposing the extreme condition on the quark propagator S(p).7) Using the nonperturbative gluon propagator Db~L (p) in the DGLtheory,3-S) the effective potential can be expressed as

into two parts responsible to the linear potential andthe Yukawa potential, respectively,3-S) Db~L(P) =Dr~ear (p) + D~~kawa (p). Hence, by examining thesetwo parts separately, the importance of the confinement effect to DXSB can be studied quantitatively. We
find that the main driving force for DXSB is broughtfrom the confinement part, Dr~ear(P)'Veff[M(O)]1. 0 r---r----,---..,...-----,

0.0

-1.0

-2.0

-3. 0oL.0------'0.'-2-----'0.-4--0--'-.-6----'0.8

feff[S ] = - iTr In(SC- 1) - iTr(SC- 1)+d4p d4q Q2 e 2/-LV(27r)4 (27r)4 -2- tr (,p,S(p) , vS(q)DDGL(P - q)) ,J

where C(p) is the bare quark propagator, and S(p)the interacting quark propagator including the gaugeinteraction effect , C-1(p) = /p + iE, S-l(p) =/ p - M (p) + iE in the chiral limit. For the energetical argument for DXSB, it is useful to examine theeffective potential Veff(M(p2)) = - feff(S) , which corresponds to the vacuum energy density as a functionof the dynamical quark mass M(p2).
Figure 1 shows Veff(M(p2)) as a function of the infrared quark mass M(O) using the quark-mass ansatz,

which is suggested by the renormalization group
analysis. 7) One finds the clear double-well structure
in Veff(M(p2)) , which has a nontrivial minimum at
M(O) ~ O.4GeV.
The nonperturbative gluon propagator is separated

M(O) [GeV]
Fig. 1. The effective potential Veff as a function of theinfrared quark mass M(O) in the dual Ginzburg-Landau
theory.

References
1) Proc. of Lattice 94, Nucl. Phys. (Proc. Suppl.) , B42 ,(1995) .
2) Y. Nambu: Phys. Rev., DID , 4264, (1974).
3) H. Suganuma, S. Sasaki, and H. Toki: Nucl. Phys.,
B435 , 207, (1995).
4) S. Sasaki , H . Suganuma, and H. Toki: Prog. Theor.
Phys., 94, 373 (1995).
5) H. Suganuma, S. Sasaki, and H. Toki: Proc. of. Int.
Conf. on Quark Confinement and Hadron Spectrum,
Como, Italy, World Scientific, p. 238 (1995); S. Sasaki,
H. Suganuma, and H. Toki: ibid. , p. 24l.
6) O. Miyamura and S. Origuchi: Proc. Int. Workshop on
Color Confinement and Hadrons , RCNP, Osaka, World
Scientific, (1995) in press.
7) K. Higashijima: Prog. Theor. Phys. Suppl. , 104, 1,(1991) and references cited therein.

Tokyo Metropolitan University
Research Center for Nuclear Physics, Osaka University

41

RIKEN Accel. Prog. Rep. 29 (1996)

New a-Decaying Neutron-Deficient Isotopes 197Rn and 20°Fr
K. Morita, Y. Pu, T. Nomra, Y. Tagaya, T. Uchibori, K. Lee, K. Uchiyama, M. Kurokawa,T. Motobayashi, H. Ogawa, M. Hies, J. Feng, A. Yoshida, S. Jeong, S. Kubono, M. Wada, K. Sueki,
T. Ishizuka, Y. Fujita, H. Miyatake, T. Shimoda, T. Shinozuka, H. Kudo,Y. Nagai, and S. Shin[new isotope , I66Er(36 Ar ,5n) 197 Rn , I69Tm(36 Ar ,5n)200Fr , E lab = 186 , 200 MeV .1
New neutron-deficient isotopes, I97Rn, I97mRn, and20°Fr, have been produced and identified on the basisof genetic correlations in the I66Er 6Ar ,5n) I97Rn(Elab = 186, 200 MeV) and I69Tm 6Ar,5n) 200Pr(E lab = 186 MeV) reactions. The results have alreadybeen published in Z. Physik A.I) See Ref. 1 for the details of data analysis and discussions. Here we present
only a brief description of the experiment together withsummarization of the results.
The 273.6 MeV 36 Ar pulsed beam (10 ms on j 10
ms off) supplied from the RIKEN Ring Cyclotron anddegraded to 186 MeV or 200 MeV with aluminum
foils was used to bombard a 1.4 mgjcm 2 I66Er target(enriched to 96.3%) electrodeposited onto a thin aluminum foil or a self-supporting 2 mgjcm 2 I69Tm target. Reaction products recoiling out of the target wereseparated from the beam by using a gas-filled recoileeseparator (GARIS).2) A two-dimensionally positionsensitive silicon detector (PSD: 64 mm x 64 mm)
was set at the focal plane of the GARIS. A large-area
micro-channel plate assembly (MCP) was set about
60 em upstream from the PSD to measure time offlights of the reaction residues between the MCP and
the PSD. The implantation signal as well as the subsequent a-decay signals were then recorded event by
event with a CAMAC based on-line data taking system. A search of time and position correlation of theevents enables us to identify decay chains like: evaporation residues -----+ first a-decay -----+ second a-decay.
Consequently, new a-decaying isotopes can be identified if the corresponding daughter nuclei are known
to be a-emitters. A summary of the measured adecay energies and half-lives are shown in Table 1.

Table 1. The alpha energies E cx and half-lives T 1/ 2 measured in the present work.
IsotopeEcx (keV)
T 1/ 2 (ms)(present work)

197Rn
193pO
197mRn193mpo96 Rn)b)
92 po)b)
2O°Fr
196 At7261 ± 306946 ± 30
7370 ± 30
6991 ± 30(7428)(7211)
7500 ± 307053 ± 30

e
e

51~~~

182~;~618~;
154~!~6(5t )(32)d)

570~i~g320~~~oReaction Channel
166Ere6 Ar, 5n)
Daughter of 197Rn
166Ere6 Ar,5n)
Daughter of 197m Rn
166Ere6 Ar,6n)
Daughter of 196Rn
169Tme6 Ar,5n)
Daughter of 2O°Fr

Ecx (keV)

Tl / 2 (ms)(literature)Ref.

6940 ± 20

360 ± 50[3]7000 ± 20

260 ± 20[3]7170 ± 20

34 ± 3[3]7055 ± 7

300 ± 100[4]

T 1/ 2 (ms)a)(systematics)
45
110
19
68
12
17
16
100

a) : Calculated by the systematics for even-even nuclei reported in Ref. 5. The Qcx values used are those determined in thiswork for the mother nuclei and those reported in the literature for the daughter nuclei.
b): Only one decay chain was observed. c): Time difference between ER - al. d) : Time difference between al - a2.

References
1) K. Morita et al.: Z. Physik, A352, 7 (1995).
2) K. Morita et al.: Nucl. Instrum. Methods Phys. Res.,
B70, 220 (1992).

423) M. Leino et al.: Phys. Rev. , C24 , 2370 (1981).
4) V. Treytl et al.: Nucl. Phys., A97, 405 (1967).
5) B. A. Brown: Phys. Rev., C46, 811 (1992).

RIKEN Accel. Prog. Rep. 29 (1996)

New a-Decaying Neutron-Deficient Isotopes 196Rn and 195 At
Y. Pu, K. Morita, T. Nomura, Y . Tagaya, T. Uchibori, T. Minemura, K. Lee,
T. Motobayashi , M. Hies, T. Ariga, A. Yoshida, K. Sueki, and S. Shin[a-decay, new isotopes, 166Er

e6Ar,6n) 196Rn, Elab 208 MeV, 164Er e6Ar,p4n) 195 At , Elab 183, 199 MeV.]=As a continuation of our previous experiment 1) ofsynthesizing new neutron-deficient isotopes such as
197Rn and 2ooFr, experiments have been performed tosynthesize more neutron-deficient radon and astatine
isotopes. Compared with the previous set-up, the detection efficiency for a-decays has been improved fromabout 50 to 80% of 41T solid angle by installing 4 solidstate detectors (SSD: 64 mm x 64 mm) around the large
position sensitive detector (PSD: 64 mm x 64 mm).2)
The experiment was carried out at E1 cave of the ring
cyclotron lab of RIKEN . A 273.6 MeV 36 Ar pulsedbeam (5ms on- 5ms off) from the ring cyclotron was degraded in energy by using aluminum foils to 208 Me V
to bombard a 1.4 mg/cm 2 166Er (enriched to 96.3%)
target and to energies of 183 and 199 MeV to bombard
a 1.2 mg/cm 2 164Er (enriched to 62%) target respectively. The beam intensity was about 1.3 x 1011 pps.
Evaporation residues (ER) were separated from thebeam by using the gas-filled recoil separator GARIS3)
and were subsequently implanted onto t he PSD located at the focal plane after traversing a large microchannel-plate (MCP) set. The energy calibration forboth the PSD and SSDs is based on a-decays fromthe implanted known 200Rn isotope and its daughter
196pO. For the bea m-on period, an a-decay signal is=distinguished from an implantation signal by the absence of an M CP signal. A true a-decay chain of thetype of ER-a1 (first a-decay)-a2 (second a-decay) is
identified with those events whose positions coincidewith each other and the time differences between them
are within reasonably short time intervals. (1) 196Rn:
In an analysis of the data obtained in the bombardment of 166Er with 36 Ar-ion at Elab = 208 MeV, three
a-decay chains of the type ER-a1-a2 have been observed. The number of accidental events has been estimated to be about 1 x 10- 5. Because the measured
a2-decay energy and its half-life agree well with the
known a-decay of 192pO as shown in Table 1, the three
a1 decays of the observed decay chains are assigned tothat of new isotope 196Rn. See Table 1 for the measured a-decay energy and half-life. The systemtics ofhalf-lives listed in the last colum of Table 1 are obtained according to the formula in Ref. 6 by using themeasured Ea values. (2) 195m,gAt : In a similar analysis of the data obtained in the bombardment of 164Erwith 36 Ar ions at Elab = 199 MeV, three kinds adecay chains have been observed. From the observed
a2 energies, half-lives and their excitation functions
they can be assigned to those of the poorly-known isotopes 195mAt (4 events) and 195 At 5) (40 events) re-

Table 1. The measured a-decay energies and half-lives of identified isotopes
in the present work in comparison with previous findings.
IsotopeEa (keV)

Till (ms)Reaction Channel

191mBi(present work)
77492 ± 30
3+ . 2807196±30
34+ . 207179 ± 30
32+32. 10986882±3O
98+ . 32

Daughter of 19SmAt

19S9At7072 ± 3055±25164Er(36Ar.p4n)

1919Bi6318±30
7152 ± 30

9±4(s)
47±28

Daughter of 19SBAt

6317±304±2(s)

196Rn
192po
19SmAt(19SAt)b)(191Bi)b)b
19SAt )c)Ea (keV)TIn (ms) Ref.

(literature)

TIIl(Ms)6)(systematics)

166Er(36Ar.6n)7428 ± 30

3 -)Daughterof 196Rn

7170±20

34±3

[4]

12
17
37

6876±20150±15[4]77

13±1 (5)140 ±50

[4]
[5]

12(5)

164Er(36Ar.p4n)6310±207190 ± 30

Daughterof(19SAt)b)6290±3013±I(s)

[5]

12(s)

164Er(36Ar.p4n)89497135± 30135±30164Er(36Ar.p4n)7125 ± 30
150 ±30[5J53a) Only one decay chain was observed in our previous work.· ) b) Only tentatively assigned and partially based on the
excitation function behavior md reaction Q·value arguments. c) a-a correlation was not observed.

spectively using similar genetic correlation arguments
described above. See Table 1 for the observed a-decayenergies and half-lives.
References
1) K . Morita et al.: Z. Phy. , A352, 7 (1995).
2) M. Kurokawa: Proc. of the Tours Symp. on Nucl. Phys.

II, Aug.30- Sept.2, p. 428 (1994).
3) K. Morita et al. : Nucl. Instr. Methods Phys. Res., B70,
220 (1992) .
4) A. Ritz: Atom. Dat. Nucl. Dat. Tab ., 47, 215 (1991).
5) M. Leino: Univ. of Helsinki, Rep. Series in Phys. HUP-D37 (thesis, unpublished)6) G. Brown: Phys. Rev. , C46 , 811 (1992) .

43

RIKEN Accel. Prog. Rep. 29 (1996)

Study of Q Decays from Evaporation Residues Produced by the
40 Ar + 232Th Reaction
M. Kurokawa, T. Nomura, T. Motobayashi , H. Murakami, Y. Iwata, T. Uchibori,T. Kikuchi, S. Jeong, Y. Tagaya, M. Wada, N. Ikeda, S. Kubono, 1. Katayama,
K. Morita, Y. Pu , A. Yoshida, Y. Nagai, H. Kudo, K. Sueki, H. Nakahara,
T. Shinozuka, M. Fujioka, H. Miyatake, Y. Fujita, T. Shimoda, and M. Tanikawa
NUCLEAR REACTION, 23 2Th(40 Ar, a3n) 265 106, E = 5.08 A MeV; measured reaction[ products, a decays, time and position correlations; gas-filled separator.
To examine possible enhancement of (HI, axn) reaction in producing superheavy elements,!) evaporation residues (EVRs) produced by the 40 Ar + 23 2Th
reaction were measured by the delayed coincidence
method.
An 40 Ar beam was accelerated to 7.6 A MeV by
RIKEN Ring Cyclotron and was degraded to about
5.08 A MeV at the center of a Th0 2 target in order
to bombard the target with an optimum energy for
232Th(40 Ar, a3n) 265 106 channel. The irradiated dose
was calculated from the counts of elastically scattered
40 Ar particles, which were detected by a silicon detector set at 45°. The produced EVRs were roughly
separated from other light reaction products by a gasfilled recoil ion separator (GARIS) with a large angular
acceptance. The selected EVRs were implanted into
a position sensitive silicon detector (PSD) with good
position resolution 2) placed at the focal point of the
GARIS. The PSD detected the EVRs themselves, thea decays from the EVRs and the decays from their descendant nuclei. For the EVRs and their a decays, thedata were recorded independently. Decay chains, consisting of EVR - t al - t a2 events, were constructed byrelating the positions and the times of the events. Besides the PSD , four silicon detectors surrounding the
PSD were used to detect a particles escaped from the
PSD. Also a time pickup detector using a micro channel plate was mounted about 60 cm upstream of the
PSD for rough measurement of the EVR's mass fromthe time-of-flight information.
The number of the extracted decay chains was six.
Figure 1 shows the a-decay energies for the chains andthey are all assigned to the decay chains from 265 106.
For the hatched area of the figure , the expected number for the accidental chain, which is formed by the accidentally correlated events, was evaluated to be 0.24
under the same position and time conditions employed
to extract the six chains. The cross section of the

44

350
232Th(40 Ar , a3n) 265106 reaction is 610+
- 250 pb , where
the errors are statistic ones. The systematic uncertainty is estimated to be a factor of three. The value
is larger than the cross section 2 pb for the 238Ue 4S,5n) 267 108 reaction, which forms the same compound
nucleus. The results suggest larger survival probability of the (HI, axn) reaction. Some improvements anddevelopments, construction of a rotating target system
and a modification of the PSD design for example, are
now in progress to reduce the accidental correlation.

9.0

Fig. 1. The three-fold coincident events, found for the
EVR-0:"1-0:"2 combination.
The horizontal axis represents the energy of 0:"1 and the vertical one is for 0:"2 .

References
1) T. Nomura: Proc. Int. Symp. on Heavy-ion Physics andits Application LanZhou, Oct. 1990, eds. W. O. Shen,
Y. X. Luo, and J. Y. Liu , World Scientific, Singapore,p. 349 (1991).
2) M. Kurokawa: Proc. Tours Symposium on Nuclear
Physics II Tours, France, Aug.-Sept. 1994, eds. H.
Utsunomiya, M. Ohta, J. Galin , and G . Miinzenberg,
World Scientific, Singapore, p. 428 (1995).

RIKEN Accel. Prog. Rep. 29 (1996)

Nuclear Moments and Charge Radii of 175Hf Determinedby Laser Spectroscopy
W. G. Jin, M. Wakasugi, M. Hies, T. T. Inamura, T. Murayama, T. Ariga,
T. Wakui, H. Katsuragawa, T. Ishizuka, J. Z. Ruan, and 1. Sugai[NUCLEAR REACTION 175Lu (d, 2n) 175Hf, nuclear moments J.L and Q, charge radii 8(r 2).]To study the isotope shift and hyperfine structure(hfs) of refractory elements, we developed a laser
spectroscopic method with an Ar-sputtering atomic
beam source. 1) Using this powerful technique, we havestarted a systematic study for Hf and Ta as well asother refractory elements. 2) This paper reports a new
result on the long-lived (Tl/2 = 70 d) unstable isotope
175Hf.
175Hf isotope with a nuclear spin 5/2 is very interesting from the nuclear-structure viewpoint because it
is in a well deformed region. However, even the signof the nuclear magnetic dipole moment is not known
and no information has been reported on the nuclear
deformation of 175Hf.
We produced the radioactive isotope 175Hf by the
175Lu(d,2n) reaction using a 19 MeV d beam from the
RIKEN AVF Cyclotron. About 10 15 atoms of 175Hf
were obtained in an area of 6 mm in diameter. The radioactive isotope 175Hf was set into our off-line chamber. The atomic beam of 175Hf was produced using

the Ar-sputtering method. Fluorescence induced bya cw ring dye laser pumped with an Ar-ion laser wasmeasured with a cooled photomultiplier.
Figure 1 shows a measured hyperfine spectrum of
the 555-nm transition for 175Hf. A peak from 174Hf
isotope produced simultaneously by the 175Lu(d,3n)reaction was also observed. From the hyperfine spectrum of 175Hf, the hfs constants for the atomic groundstate 3F 2 were determined: A = 121(4) MHz and B= 495(15) MHz. The magnetic dipole and electric
quadrupole moments were derived as J.L = -0.604(18)J.LN and Qs = 2.66(8) b. Accuracy of these values is
improved by a factor of 5 compared with the previous values. 3,4) It is shown for the first time that themagnetic dipole moment has a negative value.
The isotope shift between 175Hf and 174Hf was also
obtained as 124 MHz. Changes in mean square nuclear
charge radii 8(r2) were then derived for 175Hf and areplotted in Fig. 2 together with other data of Hf. A
systematic trend can be found from Fig. 2.

0.2

-/

~

0.1

I "
I

e

d

c

~

a

b

a 0.0

~

./

2

~

"

~

1\

N

-0.1

'"'
co
V

~4000

174Hf

j

-0.2

i

-O.S

t)

a

~ 2000

~

106

110

Fig. 2. Systematics of changes in mean square nuclear
charge radii 8(r2) for Hf isotopes.

f

o

~

100

Neutron number

t)

o

~

o

____ __ ____ ____
~

1

~

~

~~

__ ____

2
3
Relative frequency (GHz)

~

~

5

6

Fig. 1. Measured hyperfine spectrum of the 555-nm transition for 175Hf. The peaks labeled with a-e are thehyperfine peaks of 175Hf. Hyperfine splittings and transition scheme for 175Hf are shown in the upper part.

References
1) M. Wakasugi et al.: Rev. Sci. Instrum., 64, 3487 (1993).
2) W. G. Jin et al.: Phys. Rev., A52, 157 (1995), andreferences therein.
3) P. Herzog et al.: Z. Phys., B63, 241 (1986).
4) G. Kaindl et al.: Phys. Lett., B46, 62 (1973).

45

RIKEN Accel. Prog. Rep. 29 (1996)

Production of Neutron Deficient a-Decaying Hafnium Isotopes
161- 157Hf Using RIKEN GARIS/IGISOL
M. Hies, T. Ariga, T. T. Inamura, W. G. Jin, H. Kunz: K. Morita, T.Murayama, Y. Pu,
and M. Wakasugi
nuclear reaction nat Sn +48 Ti; 5.5 AMeV; production of a-decaying Hf isotopes;
gas filled recoil separator.
To investigate unstable nuclei in the refractory element region by means of laser spectroscopyl) the
production of neutron deficient a-decaying hafnium
isotopes has been performed using the gas filled recoil separator GARIS.2) The recoils are produced via
the nat Sn (48 Ti,xn) nuclear reaction using a 7.6 AMeV
48Ti-beam with the intensity of 10 pnA. The target
consists of natural tin (0.9 mg/cm 2) evaporated on 15
11m aluminum backing. The titan beam was energy degraded through the GARIS entrance window (10 11m
aluminum) and the target backing down to 5.5 AMeV.
Due to the large variety of stable tin isotopes, thecalculated cross sections results in a broad excitation
function (see Fig. 1) giving access to all a-decaying Hf
isotopes without changing the beam energy. The total
production rate of a-decaying Hf recoils, using thesecalculated cross sections and the a-decay branchingratios is calculated at 265 MeV incident primary beamenergy to 64 Hf-a-counts per sec and per pnA primarybeam current. The recoils are separated with GARIS
from the primary beam and are implanted in an open
PIN-photo diode detector (Hamamatsu S3590, 1 cm 2,
300 11m Wafer), where the a-decay energy and the recoil energy are measured.
A typical measured a-spectrum is shown in Fig.

2. All reaction channels could be assigned using thexn,pxn,axn-channels and the nuclear decay daughters.
A total Hf a-count rate of 4.0 counts per sec and per
pnA was determined at the position of the IGISOL
chamber with a recoil beam diameter of about 4 cm.
The recoil energy in the middle of the IGISOL chamber was degraded to 4 Me V using a 5 11m aluminumion guide entrance foil. The helium gas pressure inside the cell was 220 mbar. The production rate canbe explained by the calculated cross sections assuming
a GARIS efficiency in the order of 10%. Further experiments are planned to increase the production rateby improving the focusing and collection efficiency of
GARIS or using different enriched target-beam combinations like 144Sm(2°Ne,xn)-reactions or axn- reactions. How-ever, even with such a low production ratea laser spectroscopic experiment can be performed, if
using the radioactive decay measurement is used todetect the resonance ionization in a buffer gas. 3 )300
nuclear Reaction
250

na'Sn(48Ti ,xn,pxn,Qxn)
Incident Beamenergy 265 MeV

200
<fl

'E

100
1S1 HfAlice Code Calculation 124Sn( 5.8%)('\<50%)~--=162 H ! (<1.0.009%)
'--

10

E
co

.sc:
en
en
en

e

A-A0_0--0

0.1
158Hf

(am 46%)() 0.01

122Sn( 4.5%)
l2oSn(32.6%)"·Sn(7.7%)"'Sn(24.2%)~~-..A-4--i(<1.12%)0

natSn(48ri xn)172.xHf•r!)---g~~0(<<~~~:~) I/L~''''
160H

.0

U
Q>

---.

c;
100

~

50

"'Sn( 7.7%)

I L------~~

157 Hf

.

l56

4000

4500

5000

5500

6000

Energy [keVj_-(<<-91%)

j

150

:::J
0

()

Hf

Fig. 2. Measured a-spectrum for an incident titan beamenergy of 265 Me V.

(<1=100%)

0.001 +---.--.-----r-~,.----r-......,.-"'T""---r-.--"""T"""--r-~-I
200
220
240
260
280
300
320

Incident Beam Energy [MeV]Fig. 1. Calculation of cross section for the nuclear reaction natSn(48Ti,xn)Hf as a function of the incident titan
beam energy.

University of MAINZ Institute of Physics, Germany

46

References
1) M. Hies et al: This report, p. 177
2) K. Morita et al: Nucl. Instr. Methods Phys. Res., B70
220 (1992).
3) H. Backe et al: Hyperfine Interact., 74, 47 (1992).

RIKEN Accel. Prog. Rep. 29 (1996)

Measurement of Neutron Spallation Cross Sections
T. Nakamura , E. Kim, A. Konno, M. Imamura, N. Nakao,
T. Shibata, Y. Uwamino, N. Nakanishi, S. Fujita, and J. Nakajima[neutron spallation reaction, 209Bi (n,xn) reactions.]
Neutron reaction data in the energy range above 20
MeV are very poor and no evaluated data file exists atpresent. In this study, we measured the neutron spallation cross sections of C , AI, Co, Cu and Bi using aquasi-monoenergetic p-Li neutron field at the E4 experimental room of the separate sector ring cyclotron.
The proton beams having energies of 80, 90, 100, 110,
120, 135, 150, and 210 MeV were injected on a 10
mm thick Li target through a beam swinger. Protons passed through the target were cleared out by
a magnet and absorbed in a spectrograph. Neutrons
produced at 0 deg were transported through an ironconcrete collimator of 20 cm by 20 cm aperture and120 cm long. The neutron spectra were measured with
the TOF method using a BC501A organic liquid scintillator and the absolute neutron fluence was measured
with the Li activation method using the 7Be activity
from the 7Li (p,n) 7Be react ion.
The gamma-ray activities of the irradiated samples
were counted by using a Ge detector and the reaction rates of identified radioisotopes were obtained after correction of the sum-coincidence effect and self
absorption.
We could identify the produced radionuclei down to
196Bi from the 209Bi(n,14n) reaction for 150 and 210
Me V p-Li neutron. The spallation cross section data
were obtained from the neutron spectra and the reaction rates.

We are now analyzing the measured results. As examples, Fig. 1 to 3 give the cross section data of 209Bi(n,6n), (n,Sn) and (n,10n) reactions, respectively, compared with ENDF /B-VI high energy file data calculated by the ALICE code. 1) Our experimental results
show good agreement with them.

10. 1

~

e
c

0

.~

10.2

~
til
til

8U
10')

10" '--_--<.L_
40
60

_

-L...._ _..l....-_--.J~_

80

100

120

__.J

140

neutron energy(MeV)

Fig. 2. 209Bi(n,8n) reaction cross section.

10.1

t ~i·"

10°

10. 1

~

e~c
0

.~
T

I

.- ---i---

c

0

1-

10.2

U

~

•

.........+......... t....· ·.. ·;.. ·...... ·.. ...... ·.. ·10')

I-ENDFIB-VI
...
• EXP
..

ENDF/B-VI
EXP

I

8
10"

40

80

90

100

110

120

130

140

Fig. 3. 209Bi(n,10n) reaction cross section.

Ii
20

70

neutron energy(MeV)

1:- ............

10"

I

8

U

10"

til
til

u

~

til
til

---.;

e

.~

10.2

60

80

100

120

140

neutron energy(MeV)

Fig. 1. 209Bi(n,6n) reaction cross section.

References
1) National Nuclear Data Center, Brookhaven National
Laboratory, "Evaluated Nuclear Data File" , ENDF /BVI (1990).

47

RIKEN Accel. Prog. Rep. 29 (1996)

High-Spin States in 148Tbt
E. Ideguchi, Y. Gono, S. Mitarai, T. Morikawa, A. Odahara, M. Kidera,
M. Shibata, H. Tsuchida, K. Miyazaki, M. Oshima, Y. Hatsukawa, S. Hamada,*
H. Iimura,* M. Shibata,* T. Ishii,* T. Murakami, H. Kusakari, M. Sugawara,
T. Kishida, K. Morita, H. Kumagai , and M. Ishihara[Nuclear reactions, 141 Pre 3C,6n) 14B Tb, 27 Ale30Te,9n)148Tb.]
The high-spin isomers found systematically in N =83
isotones l - 6) show similar features. The excitation energies and half-lives are almost the same, i.e. ",8 MeV
and", 1 J1S, respectively, except for those of 146Eu and
149Dy. Among these isotones the level structure of
147 Gd was most extensively studied experimentally4)
and theoretically. 7) The configuration and the excitation energy of the high-spin isomer were reproduced well by the deformed independent particle model(DIPM) calculation. 7) Recently it was reported B) thatthe level structure of 145Sm could be understood within
the framework of DIPM. It is interesting to study
whether this model could be applied to interpret thelevel structure of the odd-odd nucleus 14BTb to thesame extent as those of the odd mass nuclei 147 Gd and
145Sm.
The decay scheme of the high-spin isomer in
148Tb was studied by the recoil-catcher method using 27 Ale30Te,9n)14BTb reaction at RIKEN. The
excitation energy of the high-spin isomer reported
previously5) was revised to be 8.620 MeV. The halflife of the isomer was determined to be 1.310 ± 0.007:> 14000

96MeV-1

Q)

..Y

'--"

>-

O'l

~ 10000• 144PmWo 145Sm

C

o

:.;:;

o 147Gd..8 6000• 148Tb

'ux
W

J1S.

The level structure above the high-spin isomerwas extended up to the spin (31) state at 11.8
MeV by in-beam ,-ray spectroscopic techniques using
141 Pre 3C,6n)14BTb reaction at the JAERI tandem accelerator facility.
The excited states below the (24- ) state were understood as resulted from the weak couplings of 7rh l l / 2
and vf7/ 2 to those states of 147Gd and 147Tb,9) reThe same coupling argument did notspectively.
work for the states above the (24-) state of 14BTb.
They were, however, reproduced well by the DIPM
calculation. 7) The configuration of the isomer was
given to be [7rhi1/2d~/2,vf7/2h9/2i13/2h7+ which corresponds to that of 147 Gd after filling one proton in
the 7r( d~/2)o orbits.
The deformation parameters f3 were also calculatedby DIPM for the yrast states of 14BTb. The results
exhibited the abrupt increase of the deformation at
the high-spin isomer from spherical to oblate in thesame way as reported B) for odd-A isotones, 147 Gd and
145Sm.
The average moments of inertia of N =83
Condensed from the articles in Z. Phys. , A352, 363 (1995).
Japan Atomic Energy Research Institute48

isotones 4,B,10) were estimated by plotting the excitation energies of yrast states as a function of 1(1+ 1) in
Fig. 1. They seem to have values between 77 and 96
MeV- 1 up to the highest spin state known experimentally. Those values are smaller than the rigid bodyvalues, i.e. ",110 MeV-I , for these nuclei. The detailstructure of convex shapes in Fig. 1 may be attributed
to the residual interactions l l ) among the valence particles.

2000

o ~.

.A

200

600

1000

1400

1(1+1)
Fig. 1. Comparison of the experimental yrast states of
148Tb with those of 144Pm,I°) 145Sm8), and 147 Gd. 4)

References
1) T. Murakami et al.: Z. Phys. , A345 , 123 (1993).
2) A. Ferragut et al.: l. Phys. Soc. lpn. , 62 , 3343 (1993).
3) E. Ideguchi et a~.: Bull. Phys. Soc. lpn. , p. 108 (1993).
4) M. W. Drigert et al.: Nucl. Phys., A515 , 466 (1990) ,and references therein5) R. Broda et al.: Symp. on High Spin Phenomena in
Nucl. , Argonne, March, p. 397 (1979).
6) A. M. Stefanini et al.: Nucl. Phys. , A258 , 34 (1976) .
7) T. D¢ssing et al.: Phys. Scr., 24, 258 (1981).
8) A. Odahara et al.: Z. Phys. , A350, 185 (1994).
9) Z. Meliani et al.: l. Phys. , G20, L7 (1994).
10) Y. Zhang et al.: RIKEN Accel. Prog. Rep., 21, 32(1993).
11) J. P. Schiffer and W. W. True: Rev. Mod. Phys., 48,
191 (1976).

RIKEN Accel. Prog. Rep. 29 (1996)

Life Time of High Charged States Isomer
H.-Y. Wu, T. Kishida, M. Ishihara, and E. Ideguchi[Isomer State, Half Life, Internal Conversion, Charged States, Energy level Shift.]
Changes of atomic environment can affect the nuclear reaction and decay processes. Even a nuclear
process with no electron participation, is affected by
the change of screening for ejected particle. The process that involves an electron is directly affected by
the electronic cloud near nuclear surface, such as electron capture (EC) and internal conversion (Ie). The
variation of transition rate is essentially proportional
to the change of electron density available at the nucleus. Another effect is due to the atomic energy level
shift. For example, the binding energy of a K-shellelectron is shifted to an excitation energy higher than
the threshold of the Ie for the isomer state of 125Te,
which strongly affects the life time of the isomer (Table
1).
Table 1. Comparison of the observed and calculated life
time of isomer state of 125Te, with 35.49 keY of thetransition energy.
chargestat e040

E~ (keV)T 1 / 2 (ns )confi g .
(neutral)(38 2 )

Exp.
1.49

calc a )1.49

caleb)
1.49
2.1
2.8
3.3
3.9
1 5.1

calc c )
1.49
1.50
1.53
1.54
1.58
10.0
10 .2
13.9

ReId)

Rer)

31.81

31.81

this work
31.81
34.17
(2 s22p4)
44
1.5
35.27
35.09
2
(2s 2p 3) > 2
45
8.0
35.61
35.58
35.33
(2s22p2)
46
8.3
35 .91
35.91
35.56
> 2
(2s22p1) 6±1
47
8.5
36.26
36.26
35.81
48
(28 2 )
10.3
40.3
36.60
11±2
36.60
36.04
1
49
(28 )
55 .8
36.28
(1s2)
50
90.3
21.9
36.53
a),d),e) FraIn R ef. 3 and Its re f e r ence. b) Th,s work, M1 and E2 Inlxture typetransition Ref. NNDC. c) Thi s work, M1 type transition.

The Ie coefficient a is given by non-trivial orderof perturbation theory. The electron wave function is
given by a set of coupled Dirac differential equations
for a central potential V (r ), that includes the screening
and exchange effects. The electron wave function was
calculated using the WKB screening approximation l )for different charge states. The a, for nuclei with nuclear charge Z and electron number Q, can be deducedasa(Q) =~ [aa (~~) a (~i:;)] ,where Wand P are energy and momentum of Ie electron for sub-shell 0', the prime denotes the quantitywith screening correction, and NJZ) and NJQ) are numbers of 0' shell electrons for neutral and charged states,
respectively. The screening effect for W' and P' is calculated by using Thomas-Fermi model. 2)

1 0 , - - - - -- ---,

(b)

(a)

~ -.
E-,......

-6"

<l

- II

..........

~ - ,o ","""""..-n

.

s

~

-5
-10 F""=..............---.z-..L..-........J...----j

<I

tID

.2

-5

Fig. 1. Relationship between the half life change andcharged states of 149Dy for different transition type (Energy= 50 keY) (a) and for different energy (E2) (b).

Figure 1 shows the results of calculations. The a isa function of transition energy, the type of transition,and charged states. For the ionization process , thechange of life time is larger when the transition energy
is smaller. The change becomes also larger for a transition with higher multipolarity. Magnetic transitions
are more affected than the electric transitions. The
life time of excited states in highly charged atoms isincreased extremely because it is determined only bythe "Y transition without internal conversion. All thefigures show the structure of shell and sub-shell. Thechanges of life time are mainly contributed by Is and2s orbits.
In an isomer beam with energy greater than 10 MeV/nucleon, where the atoms are nearly bare, some isomer states for a special transition type may have a longlife time. 3 ) At a beam energy lower than 10 MeV /nucleon or a transition with higher energy than 400 Ke V,
the change of life time is relatively small. Although
the changes of the isomer life time are at most 1% in
the case of the present high spin isomer beam line of
RIKEN,4) this effect will become very important for
RIKEN RI Beam Factory, where isomer beams withhigher energies may be involved.
References
1) M. E. Rose: Phys. Rev., 49, 727 (1936).
2) W. R . Garrett et al.: Z. Physik, 198, 453 (1967).
3) F. Attallah et al.: Phys. Rev. Lett., 75 , 1715 (1995).
4) T. Kishida et el.: RIKEN Accel. Prog. Rep. , 28, 50(1995).

49

RIKEN Accel. Prog. Rep. 29 (1996)

Target Dependence of Production Rates
of Projectile-like Fragments
M. Notani, H. Sakurai, N. Aoi, M. Hirai, H. Kobinata, Y. Watanabe,
T. Nakamura, A. Yoshida, Y. Watanabe, T. Kubo, T. Nakagawa,N. Inabe, H. Kumagai, A. Goto, and M. Ishihara
NUCLEAR REACTIONS 9Be, 181Ta(50Ti,X), E(50Ti) = 80A MeV;
[ Target Dependence of Fragment Production Rate.
Radioactive ion beams produced by the projectile
fragmentation reactions are a very useful tool in nuclear physics. The production mechanism of projectilelike fragments at intermediate energies (10rv 100 A
Me V) has been investigated to understand the mechanism itself, then to make precise prediction of the secondary beam intensity for designing experiments. It
was reported that the production yields of the neutronrich isotopes with 44A MeV 48Ca beam are strongly
dependent on the N jZ ratio of the target. 1) Here we
present our results on the target dependence with ahigher energy beam, 80A MeV 50Ti.
We used two energy-loss-equivalent targets, 9Be and
18 1Ta, with thickness of 289 and 435 mgjcm 2, respectively. Details of the experiment are described
elsewhere. 2) We accumulated data with Bp=3.45Tm
setting of the RIPS spectrometer. Figure 1 shows production yields of projectile-like fragments for 17- 22 N,
19- 24 0 , 21- 27 F , 24- 30 Ne, 27- 33 Na, 30- 36 Mg, and33-38 AI. We found that 181 Ta can earn several times
larger yields of the neutron-rich nuclei with AjZ rv 3
than 9Be.
Figure 2 shows the experimental cross sections andpredicted ones by the INTENSITY code. 3) This code isbased on the participant spectator models, taking into
account only the fragmentation mechanism, and has
been widely used in designing experiments. The experimental cross sections were obtained from comparisons
between the experimental yields and predicted ones.

10 1

'"c

10 0

Q,

.::.
c

10- 1

~

0

u

":;:

10 - 2

Ne

1

Na

x 9Be-Target
o 18ITa-Target/2. 1--Calc.(INTENSITY}100~~,:"'('o". '''')

1
[5

~

10 - 3

...0

u

10- 6

15

20

25

30

35

40

Fig. 2. Production cross sections of projectile-like fragments for 9Be and 181Ta targets, compared with thecross sections calculated by the INTENSITY code andby the modified one. The cross sections for 181Ta targets are divided by a factor of 2.1; thus one prediction
curve for each isotope presents the cross sections for twotargets at once.

To minimize ambiguities of the INTENSITY parameter set for the cross section evaluation, we chose the isotopes with their momentum acceptance of more than
0.1 %. As seen in Fig. 2, the INTENSITY cannot
predict well the experimental cross sections for very
neutron-rich nuclei.
An attempt to improve the INTENSITY prediction
by tuning parameters was made for projectile-like fragments from 93.6A MeV 40 Ar+ 9Be reactions. 4) This
modified INTENSITY by use of the new parametersdescribes fairly well the production cross sections for
50Ti + 9Be reactions, but underestimates the cross sections of neutron-rich nuclei for a 181Ta target (see Fig.
2) . This discrepancy cannot be explained in terms of
only the fragment~tion reaction and suggests that thetransfer reaction plays a significant role even at thisbeam energy.

10- 3References

10- 4
15

20

25

30

35

40

Fig. 1. Production yields for the isotopes of N, 0, F,
Ne, Na, Mg, and Al obtained with targets of 9Be and181Ta in the reactions with 50Ti beam at 80A MeV. The
thickness of two targets was energy-loss-equivalent for
the incident beam.

501) D . Guillemaud-Mueller et al.: Phys. Rev., C41 , 937(1990).
2) H. Sakurai et al.: This report, p. 51.
3) J. A. Winger, B. M. Sherrill, and D. J. Morrissey: Nucl.
Instrum. Methods Phys. Res., B70, 380 (1992).
4) Y. Doki: JAERI-M 94-028, p. 70; Master thesis, Tokyo
University (1994).

RIKEN Accel. Prog. Rep. 29 (1996)

Production and Identification of New Neutron Rich Nuclei 31Ne
and 37Mg with 80 A MeV 50Ti Beam
H. Sakurai, T. Nakamura, M. Notani, T. Kubo, A. Yoshida, H. Kumagai, Y. Watanabe,
T. Nakagawa, A. Goto, N. Inabe, N. Aoi, M. Hirai, Y. Watanabe, H. Kobinata, and M. Ishihara
NUCLEAR REACTIONS 181Ta(50Ti,X), E(50Ti) = 80 A MeV; deduced fragment[ production rate vs mass and Z; evidence for 31 Ne, 37Mg.
An attempt to synthesize new neutron rich nuclei in
10 ~ Z ~ 13 region can be made by means of the Riken
Projectile Fragment Separator (RIPS).1) The total effective acceptance of such nuclei at RIKEN is about
two orders of magnitude higher than at the GANILLISE.2) Here, we report the first production and identification of new neutron rich nuclei 31 Ne and 37Mg
with 80 A MeV 50Ti beam.
50Ti ions provided by the ECR were accelerated in
the AVF and RING Cyclotron to an energy of 80 A
MeV. At the ECR, 60% enriched 50Ti-oxide powder
was used as the ion source material. The oxide powder
was contained into a ceramic rod which was moved
toward the plasma by about 100 J.tm step every hour,
and the average beam intensity was rv2 pnA. From thestudy on target dependence of fragment yields,3) weused a 435 mgjcm 2 thick 181Ta target.
Reaction products were analyzed with the RIPS
spectrometer operated in the achromatic mode. 1) The
particle identification of our experiment was performed
event-by-event in a more redundant way than thatof the GANIL experiment,4) by means of measurements of magnetic rigidity, time-of-flight, energy deposit (flE) and kinetic energy (E). At the momentum
dispersive focal plane F1, a Parallel Plate Avalanche
Chamber (PPAC) was mounted for Bp measurements.
At the final focal point F3, all other detectors were located; a 0.5 mm thick plastic scintillation counter (PL),two 0.3 mm surface barrier type silicon detectors, andtwo 3 mm thick lithium drift silicon detectors. The
time-of-flight of fragments was obtained from the PL
timing and RF signal of the cyclotron. The flE measured by use of the first three silicon detectors leads tothree independent determinations of Z with accuracyof 0.1 % (r.m.s.) for Z rv 10 nuclei. The mass to charge
state ratio, Aj Q, of fragments was determined fromthe magnetic rigidity and time-of-flight, and the mass
A from the E and time-of-flight, hence finally Q - Z
was reduced for the fragments which stopped at the
final silicon detector. The accuracy of Aj Q and Q was
about 0.2% in r.m.s. This method can resolve uncertainty of charge states as backgrounds against neutronrich nuclei, and provide a very clean particle identification. Taking into account energy loss in the target
for both the beam and fragments with AjZ rv 3.1, themagnet rigidity of the RIPS spectrometer was set to
be 3.6 Tm. We accumulated data for 4 days to search
for new neutron rich isotopes.

1

After piling-up rejections and requiring a fully
stripped condition for fragments, we obtained the twodimensional plot, AjZ versus Z, as seen Fig. 1. We
have observed new isotopes 31Ne (23 events) and 37Mg
(3 events). The previous GANIL experiment 4) reported that no events associated with 31Ne were found,and concluded that 31 Ne was unbound. This discrepancy could be caused by less statistics andj or less feasible separation of fragments at the GANIL, where Bp
measurements were not involved in particle identification. We observed nine events of 32Ne, while the
GANIL people had four events. In addition, for theparticle stable' nucleus 34Na, we had fifteen events, butthey had no events.
For the first time, this experiment produced andidentified the new neutron rich nuclei 31 Ne and 37Mg,
and showed that those nuclei are particle-stable nuclei.

15

14

13

3711g

'" 12

11

10

291=
2.7

2.B

2.9

3.3

Fig. 1. Two-dimensional A/Z versus Z plot obtained in
the fragmentation reaction of the 50Ti beam at 80 A
MeV on a 435 mg/cm 2 tantalum target during a 4-day
run with magnetic rigidity Bp=3.6 Tm of the RIPS
spectrometer. The 3INe isotope (23 counts) and 37Mg
(3 counts) are clearly visible.

References
1) T. Kubo et al.: Nucl. Instrum. Methods Phys. Res.,
B10, 309 (1992).
2) R. Anne, A. C. Moller, J. C. Jacmart, and M. Langevin:ibid., A257, 215 (1987).
3) M. Notani et al.: This report, p. 50.
4) D. Guillemaud-Mueller et al.: Phys. Rev., C41, 937(1990).

51

RIKEN Accel. Prog. Rep. 29 (1996)

Giant Dipole Resonance in Hot Rotating Nuclei
Y. Aoki, R. Sasaki, T. Ohtsuki, J. Kasagi, K. Yuasa-Nakagawa,
K. Furutaka, Y. Futami, K. Yoshida, T. Nakagawa, and T. Suomijarvi*
NUCLEAR REACTIONS: 40 Ar + 92Mo, 116Sn, 124Sn and natNi at E = 7 /MeV /nucleon,[ Heavy ion fusion reaction, Giant dipole resonance, ,-ray multiplicity.
In order to understand the mechanism of broadningof the GDR width in hot nuclei, it is very important to separate the effect of angular momentum fromthat of the temperature. We measured high energy,-rays emitted from hot compound nuclei formed in
the 40 Ar + 92Mo, 116Sn, 124Sn and natNi reactions together with the ,-ray multiplicity which is a measureof the angular momentum. The experiments were performed at RIKEN Ring Cyclotron Facility. Self supporting metallic foils were bombarded with 40 Ar beams
at E = 7 MeV/nucleon. High energy ,-rays from thecompound nucleus were detected with 2 sets of highenergy ,-ray detectors placed at 90° and 130° with respect to the beam direction. Each detector consistedof 7 BaF 2 scintillators; only the centor one was irradiated to improve the detector response. ,-ray multiplicities were measured with a ,-ray multiplicity filter
composed of 62 BaF 2 scintillators covering 1/3 of 4 7r.
The TOF method and the pulse shape analysis wereused to reject the events due to neutrons or charged
particles.
Compound nuclei formed in the heavy ion reactions
have high angular momenta. The estimated criticalangular momenta for complete fusion are about 75 n
for 40 Ar + 92Mo, 116Sn and 124Sn reactions, and 70
Ii for 40 Ar + nat Ni reaction. We analyzed the eventswith M-y ~ 5 for a Ni target (M-y is the number ofther fired detectors) which corresponds to 60 n of theaveraged angular momentum, for with M-y ~ 8 whichcorresponds to 70 Ii for other reactions. By selecting
these high angular momentum events, ,-rays from thenuclei excited by deep-inelastic collisions which bringthe angular momentum up to 30 n are discriminatedfrom the fusion events.
Figure l(a) is the ,-ray energy spectra obtained in
the 40 Ar + 124Sn reaction for M-y ~ 8; solid circles are,-rays detected at 90° and open circles are at 130°.
The data at 130° are corrected for the Doppler shifts.
Broad bumps due to the decay of GDR are clearlyseen for E-y > 10 MeV and the spectral shapes arevery similar for both angles. In order to see the difference between these two spectra more clearly, theratio of the spectra, W(1300) / W(900), is plotted inFig. l(b), which shows more or less isotropic except
for 8 < E-y < 12 MeV. The spectra measured in the
40 Ar + natNi reaction for M-y ~ 5 are shown in Fig. 2

Institute de Physique Nucreaire, IN2P3-CNRS

52

1

together with the ratio of their spectra. In contrast to
the case of the 40 Ar + 124Sn reaction, the spectrum
observed at 130° shows an enhancement to the one
at 90° at around E-y e:! 20 MeV; this is clearly seenin Fig. 2(b). These observations can be interpreted as
the effect of deformation and rotation of the compound
nucleus since anisotropy of the G D R decay ,-rays fromdeformed rotating nuclei depends strongly on the ,-rayenergy. 1) More quantitat ive analysis is now in progress.

•0

S

~

·1

~ 10

2.5

Ar+

•

•

~ 10.2

f
•

I

~

10

~

,

20

15

25

2
1.75
1.5

i 1 .2~

•• +

..

10

(b)

2.25

-=--

0

~

Sn (7MeV/n)(a)~ 0.75

o <>

0.5
0.25
10

30

15

20

25

30

E/MeV)

E/MeV)

Fig. 1 (a) , -ray energy spectra obtained in 40 Ar + 124Sn
reaction at E = 7 MeV / nucleon for M-y ~ 8. Opencircles show the spect rum obtained at 130 0 and closed
circles the spect rum obtained at 90 0 • (b) Ratio of the
2 spectra in (a).

S
~ 10.1!

~ 10·22.5

Ar + D&lNi (7MeV/n) (a)

•

•
~
'

~ ~

i

ei 0

~

~

2

~

1 75

~

(b)

tt

1.5
.
1.25

~

9

---.:::T

i 0.75

• 0

••+
10

2.25

0<>9

0.5

..

0.25 F101520E/MeV)

25

30

I

I

I

10

15

20

t

2~

30

E/MeV)

Fig. 2 (a) ,-ray energy spectra obtained in 40Ar + nat Ni
reaction at E = 7 MeV/nucleon for M -y ~ 5. The notations are the same as those in Fig. 1 (a). (b) Ratio of
the 2 spectra in (a).

References
1) P. Thirolf et al.: Nucl. Phys., A482, 93c (1988).

RIKEN Accel. Prog. Rep. 29 (1996)

Entrance Channel Effect on the Pre-scission Time of Binary Decay
for Medium Mass Nuclei (Mass rv 110)t
K. Yuasa-Nakagawa, T. Nakagawa, K. Furutaka, K. Matsuda, * Y. Futami,
K. Yoshida, J. Kasagi, S. M. Lee, T. Suomijarvi,** W. Q. Shen, and T. Matsuse
NUCLEAR REACTIONS: Binary decay fragments, Pre- and post-scission charged particle
multiplicities, Pre-scission time, Entrance channel effect , Average angular momentum.
In the heavy ion reactions at low to intermediate
energies, the dynamics of a binary decay process is
considered to be one of the most interesting topics.
It provides an excellent ground to test nuclear manybody theories. In such reactions the angular momentum brought into the system has proven to playa vitalrole in the characterization of various decay processes
and it also contributes to the interaction time of thereactions.
We have studied the dependence of interaction timeon the entrance channel mass asymmetries and angularmomenta for a medium mass system using pre-scission
charged particle multiplicities.
The experiment was performed using the large scattering chamber (ASCHRA). The multiplicities of protons and a particles have been measured in coincidence with a binary decay fragment in the reactionsof 84Kr + 27 Al and 58Ni + 56Fe at the incident energies of 10.6 and 10.0 MeV/nucleon, respectively. These
two systems lead to similar composite systems withalmost the same excitation energy. Heavy fragments
were detected at 10 degrees by a time-of-flight counter
telescope consisting two channel plate detectors and alarge solid state detector. Light charged particles weredetected with the 37r multi-detector system which iscomposed of 120 phoswich detectors that cover the angular range between 10 to 160 deg. in the laboratory
angle. A phoswich detector consists of a thin plastic
scintillator and a thick BaF 2 crystal. It can identify
not only light charged particles but also neutrons and,-rays.
The obtained energy spectra of protons and a particles were fitted by three source analysis and the preand post-scission charged particle multiplicities wereextracted.
To evaluate a pre-scission time of the composite system, we made a statistical calculation using two statistical models. In the GEMINI,l) the pre-scission time
was calculated by introducing the fission delay time. In
the extended Hauser-Feshbach Method (EHFM) ,2) wehave introduced the cut-off of the excitation energy of
two fission fragments. The results obtained by two calculations match one another within 20% discrepancy.
In Fig. l(a) the obtained pre-scission time is plottedby closed circles as a function of entrance channel mass
Condensed from the article in Phys. Lett., B351, 77 (1995)
Mitsubishi Electric, Co.
Institut de Physique Nucleaire, Orsay, France

asymmetries. The result of 16 0 + Ag is taken from
Ref. 3. In Fig. 1 (b) the pre-scission time is plotted asa function of the average angular momentum of binary
decay.
As shown in the figures, it is clear that the difference of the entrance channel makes a great contribution to the pre-scission time. Dynamics of the entrance
channel should be considered in the calculation of prescission time. We have applied the method proposed
in Ref. 4, i.e. , the combination of the code HICOL 5)
and a statistical calculation. The calculated resultswith entrance channel dynamics are shown by open circles in the figures. The slope in the Fig. 1 (b) became
gentler than that of the statistical calculation, however, the tendency is not changed, i.e. , the pre-scission
time increases as the average angular momentum decreases. This is comprehensible because the larger angular momentum which leads to the larger centrifugal
force helps the system to make a binary decay.

a)

b)~
~

+ ItO'~••:1cb 10.~

+

O+A\

~

Kr+AI

Ii:
Ni+ Fe10·21'--'-.,....,....~~~

o

0.2

0.4

0.6

0.8

I Ar·Apl
Mass asymmatry( (AT+ Ap»

70

90

Average Angular Momentum (1'1)

Fig. 1. (a) The extracted statistical pre-scission time andthe result of the calculation with entrance channel dynamics are plotted as a function of the entrance channelmass asymmetry. (b) The extracted pre-scission times
are plotted as a function of average angular momentum
for binary decay of the systems. For both figures, theclosed circles show the pre-scission time deduced by thestatistical calculations and the open circles are the results of the calculation with entrance channel dynamics.

References
1) R. J. Charity et al.: Nucl. Phys. , A483, 371 (1988).
2) T. Matsuse et al.: Proc. Int ., Symp. NIKKO '91, Y.
Abe et al. (eds.), AlP, New York, p. 112 (1991).
3) D. J. Hinde et al.: Phys. Rev., C45, 1229 (1992).
4) K. Siwek-Wilczynska et al.: ibid., C51, 2054 (1995).
5) H. Feldmeier: Rep. Prog. Phys., 50, 915 (1987).

53

RIKEN Accel. Prog. Rep. 29 (1996)

Temperature and Excitation Energy of Hot Nuclei Produced in
40 Ar + 116Sn Reaction at E/ A=30 and 37 MeV/nucleon
K. Furutaka, K. Yoshida, A. Yajima,* Y. Akeboshi,** K. Matsuda,** T. Murakami, J. Kasagi,
T. Nakagawa, K. Yuasa-Nakagawa, Y. Futami, A. Galonsky, and G. Bizard
NUCLEAR REACTIONS: 40 Ar + 116Sn at EIA = 30,36.4 MeV lu; measured neutron, proton
and a particle energy spectra and angular distributions; moving source analysis.
Properties of hot nuclei produced in intermediate
energy (10 S E I A S 100 MeV) heavy ion reaction
have attracted much interests in recent years. Amongthem, the relation between temperature and excitation energy, i.e. the level density parameter, of the hot
nuclei has been of a great interest. In light charged
particle measurements, a decrease of the level density
parameter a from AI8 to AI13 (A: mass number) was
observed,1,2) while experiments in which neutrons weredetected showed that their spectra were well reproduced by the statistical model calculations with a =AI8. 3 - 5 ) To resolve these contradictory results, a series of experiments were performed in which neutrons,
protons and alpha particles emitted in 40 Ar + 116Sn
reactions at E I A = 30 and 37 MeV were measured incoincidence with heavy evaporation residues(ER).
Self-supporting foil of 116Sn (about Img/cm 2) was
bomberded with 30 and 36.4 MeV lu 40 Ar beams. Neutrons were detected with 22 liquid scintillation detectors and their energies were measured through theTime-of-flight (TOF) method. TOF lengths ranged
from 0.8 m to 2.4 m. Detection angles were between 30
and 155 deg. Overall time resolution was about 1.5ns(FWHM) for prompt gamma rays. Protons and alphaparticles were measured in the separate run with 80
phoswich detectors composed of a BaF 2 crystal and athin plastic scintillator. Heavy residues were detectedwith 4 stacks of a MCP-MCP-Si detector array placed
at 10 deg. with respect to the beam direction. Mass
AER and velocity V ER of the residues were deduced.
Events were devided into 4 groups according to VER
as a measure of energy and momentum transferred tothe hot composit system, and thermal excitation energies Eth were deduced for each group. Firstly, slope
parameters (or apparent temperatures) Ti and multiplicities Mi of the particles were deduced through themoving source analysis of the spectra, in which two
isotropic emission sources with the Maxwellian shapewere assumed. One source corresponds to the emission
from a pre-equilibrium-like source with rv1/2 beam velocity, while the other describes the equilibrated hot
nuclei which are assumed to be moving with VER .
Surface type Maxwellian emission was assumed for all
sources except for the equilibrium neutron source, forwhich volume emission was used. Then average energies of the particles emitted from the equilibrium com**54

Present address: Toshiba Electric , Co.
Present address: Mitsubishi Electric, Co.

ponent Ei,eq were calculated from Teq. After that, Eths
were calculated by using the following relation

i=n,p,Q

instead of a traditional calculation method using VER
based on the massive transfer model. Ec and Bi standfor Couromb energy and binding energy of a particle
i, respectively. E"{ is the energy removed through the,-ray emission process.
In Fig. 1 extracted apparent temperatures of the hot
nuclei (the equilibrium sources) were plotted against
the thermal excitation energies deduced from Eqn. (1).
Dotted lines were the results of statistical model calculations using the code CASCADE6) with level density
parameters from AI8 to A113. From the figures it canbe said that the excitation energy dependence of thetemperature parameters of the hot nuclei produced inthese reactions is well described by using the level density parameter a rv AI8 to AII0 and the parameters
are almost the same for all particles.

%

J.-+

-;:

3

a - Al B

0:particle~Z'.,I-...

Il ""A/l 3

].
5

.#4+-

0..

]

~§:

3

4 ::.04 / 13

prolona 37l1eV/ n

6

0_.",

5

«

~

a - A/ Bt*

2 ~~~~~~~~~oI

Excitation Energy per Nucleon (MeV I n)

Fig. 1. Apparent temperatures were plotted against
the thermal excitation energies deduced from Eqn. (1).
Dotted lines are the results of the statistical model calculations with a from A/8 to A/13.

References
1) D. Fabris et al: Phys. Lett., B196, 429 (1987).
2) R. Wada et al: Phys. Rev., C39, 497 (1989).
3) E. Holub et al: ibid. , C28, 252 (1983) .
4) D. Hilscher et al: ibid., C36, 208 (1987).
5) K. Yoshida et al: ibid., C46, 961 (1992).
6) F. Piihlhofer: Nucl. Phys., A280, 267 (1977).

RIKEN Accel. Prog. Rep. 29 (1996)

Measurement of the d-p Elastic Scattering at Ed = 270 MeV
N. Sakamoto, H. Okamura, T. Uesaka, S. Ishida, H. Otsu, T. Wakasa, Y. Satou,
T. Niizeki, K. Hatanaka, Y. Koike,* and H. Sakai
NUCLEAR REACTIONS 1 H(polarized d, d), E = 270 MeV; measured (]'(B),Ay(B), Ayy(B), Axx(B), and Axz(B); Faddeev calculations.
In this report we present new data of the differential
cross sections for the d-p elastic scattering at E~ab =270 Me V and a comparison between predictions of a
Faddeev calculation and the experimental data of thedifferential cross sections and all components of theanalyzing powers. 1)
The differential cross sections have been measured
in the same angular range of the analyzing power
measurement.1) The deuteron beam which was accelerated up to 270 Me V by the RIKEN Ring Cyclotron
bombarded the polyethylene film with a thickness of 40
mg/ cm 2 . The data were taken by a kinematical coincidence method in order to discriminate the d-p elastic
scattering from other scattering processes such as theelastic scattering by carbon or the deuteron break-up
process. The contribution of the 12C( d, dp) 11 B knockout reaction whose final products are indistinguishable
from those of the d-p elastic scattering has been measured at an angle Bc . m . = 86.6 0 by using a carbon

1.0 r - - --- - - - - -- - - ,j ~ 3 .

target and found to be less than 1%. The total uncertainties in the final cross sections are statistical errorof ± 1% and a systematic error of ± 6%.
The analyzing powers and the differential cross 8ections are compared with predictions of a Faddeev calculation in Fig. 1 and Fig. 2, respectively. The Faddeev
calculation was made by using a separable expansion
method 2 ) employing the Argonne V14 potential. The
solid and dashed curves are the results of the Faddeev
calculations with the Argonne V14 NN partial wave
interactions of j :S 4 and j :S 3, respectively. All components of the analyzing powers are well reproduced.
Incl usion of the j = 4 higher partial wave only slightly
improves the fitness of the calculated analyzing powers. In contrast, the fit to the differential cross sections
is poor. The calculated cross sections are 30% smaller
than the experimental values at angles around Bc .m . =120 0 where the cross sections have a minimum. Inclusion of the j = 4 partial wave does not improve thefit. This might imply that a tuning of the Argonne V14
potential is needed although the analyzing powers aredescribed well.

j ~ 4

0 .5
0.0 1 - ' - - -- T - -------"f --""1

-0.5
1.0

..

0.5

0.0 ~=----------_______1

0.5
0.0 r = -- - - ----+------1- 0 .5

o

1.0

0 .5
0 .0 r---~--------___1

o

60

120

180

8 c .m . (degree)

Fig. 1. The analyzing powers for the d-p elastic scatteringat Ed = 270 Me V. The error bars are statistical ones
only. Dashed and solid curves are the results of Faddeev
calculations with the Argonne V14 NN interaction for j~ 3 and j ~ 4, respectively.

60

120

180

ec .m . (degree)

Fig. 2. The differential cross sections for the d-p elastic
scattering at E~ab = 270 MeV. The systematic errors
are not shown in the figure. Solid and dashed curves
are the same as in Fig. 1.

References
1) N. Sakamoto et al.: RIKEN Accel. Prog. Rep., 27, 39(1993).
2) Y. Koike et al.: Phys. Rev., C42, R2286 (1990).

Department of Physics, Hosei University

55

RIKEN Accel. Prog. Rep. 29 (1996)

Elastic Scattering of Polarized Deuterons at Ed = 270 MeV
T. Ohnishi, H. Okamura, S. Ishida, H. Otsu, N. Sakamoto, T. Uesaka, T. Wakasa,
Y. Satou, S. Fujita, T. Nonaka, and H. Sakai[NUCLEAR REACTION 12C, 40Ca, 90Zr, and 208Pb(d, d); measured a(e),Ay(e),Ayy(e),Axz(e).]We have measured the differential cross sections
and the vector and tensor analyzing powers, Ay andA yy , for the elastic scattering of polarized deuterons
at Ed1ab = 270 MeV from 12C, 40Ca, 90Zr and 208Pb
targets. We also measured Axx and Axz for the
40Ca target, because these quantities are useful forthe study of the tensor interaction. 1) To measureAxx and A xz , it is neccesary to control the angleof quantization axis with respect to the beam direction. In a previous experiment ,2) only the tensor analyzing power A;x, which is a combination of
A xx , Ayy and A xz , was measured. We establisheda new method of controlling the direction of quantization axis using a Wien filter at RIKEN. 3 ) The

present data is the first measurement of the complete
set of the analyzing powers at intermediate energies.
The vector and tensor polarized deuteron beams
were provided by the polarized ion source and accelerated up to 270 MeV by the RIKEN Ring Cyclotron.
The scattered deuterons were analyzed by the spectrometer, SMART. The energy resolution was 200 keV(FWHM).
The angular distributions of the differential crosssections are plotted in ratio to Rutherford cross section in Fig. 1. Figures 2, 3, and 4 show the angular
distributions of the analyzing powers, A y , A yy , Axx
and A xz . The error bars are statistical only. The optical model analysis is in progress.

102
1.00
0."111101

0.&0O.lll!
0.00
100

I>:

b
'0

0."111
10- 1

0.&0

o.ae

.........

b
'0

J

10- 2

'" '.

.

"'Ca

'

'

.......

'.'""zr.+..'.••·t··• •• +.++IH

0.00
1.00
0."111

10-3

...•
•.
...
..
. .............
..... ••••.. .'... ..
.
......

IIC

0.&0

O.lll!

,V'··:

0.00
10-'
1.00
0."111
10-&

20

10

0

0.&0

so

O.lll!
0.00

8 c.m Jdeg]

Fig. 1. Angular distributions of cross section for the
deuteron elastic scattering from 12C, 40Ca, 90Zr, and
208Pb at E d1ab = 270 MeV.
1.00

....
•••••••••••.• .....

l"c"0."111
0.&0

O.lll!

..

'.'

1.00

0.00
-0.211

J -0.&0
-0.7&
-1.00
1.00

Ca

'

0.&0

O.lll!

.... .. ..

.'

0.00

<"
1.00
0."111
0.&0

O.lll!

.

""zr..
...,./••++ ++•••••••••••••••

'

..
....

........ '.

.. ++++.\ ........
......

1..

I
I.....1..

.. .I. ...

..................

I
I

1

I
1

0.7&

.f

0.&0

..........................
.
I·
" j'

O.lll!
0.00········· ·1· ··...... ·j ·..
10•••••• •••••••• +40

Fig. 3. Angular distributions of analyzing power A yy .

'40." ............

20so
9 c.m1deg]

0.00

0."111....., .. ..

MMlpb

20
so
9 c .m.[deg]Fig. 4. Angular distributions of analyzing powers Axx andAxz from 40 Ca.

0.00
1.00
0 ."1110.&0O.lll!
0.00

MMlpb. ' ..'....

:.,.
"""........

Fig. 2. Angular distributions of analyzing power A y .

56

References
1) Y. Iseri et al.: Nucl. Phys., A533, 574 (1991) .
2) T. Uesaka et al.: RIKEN Accel. Prog. Rep., 27, 40(1993).
3) H. Okamura et al.: AlP Conf. Proc., 343, 123 (1995).

RIKEN Accel. Prog. Rep. 29 (1996)

Measurement of the 12C(d, d') Reaction at Ed = 270 MeV
Y. Satou, S. Ishida, H. Okamura, N. Sakamoto, H. Otsu, T. Uesaka, T. Wakasa, S. Fujita,
T. Ohnishi, T. Nonaka, H. Sakai, T. Ichihara, T. Niizeki, N. Nishimori, and K. Hatanaka[NUCLEAR REACTION, deuteron inelastic scattering, Ed = 270 MeV.]
The study of spin excitation in nuclei is one of themost interesting issues in nuclear physics today. In
recent years ~S=l strength has been located in several nuclei by measuring spin-flip probability in the(p, p') reaction. For ~S=l transitions induced by proton, however, the isovector (~T=l) part of the N-N
effective interaction mainly contributes to the excitation of the nucleus. Hence very little is known about
the isoscalar (~T=O) ~S=l strength except for somecases.1) To study the isoscalar spin strength in nuclei by using the (d~ d') reaction, we have newly developed the Deuteron POLarimeter DPOL which candetermine all the vector and tensor polarization components of scattered deuterons simultaneously by utilizing 12C( d, d), 1H( d, 2He) and 1H( d, d) reactions. 2)
The measurement of the 12C(d, d') reaction was carried out by using a 270 Me V polarized deuteron beamfrom the RIKEN Ring Cyclotron. This was the firstpolarization transfer measurement making use of the
DPOL. Details of the polarized deuteron beam are described elsewhere. 3 ) Inelastically scattered deuterons
were momentum analyzed by a magnetic spectrograph
SMART and their positions were determined by a multiwire drift chamber (MWDC) located at the second focal plane (FP-2). Elastically scattered deuterons were
stopped by a 5 cm-thick lead slit placed at the first
focal plane (FP-1). The energy resolution was about
200 keV (FWHM) with a natural carbon target of 87.2
mg/cm 2 thick. Two plastic trigger counters, whichwere placed downstream of the MWDC and accompanied with a 2.5 cm-thick polyethylene plate, were usedas polarization analyzer targets. Scattered particles
from the analyzer targets were detected by the plastic
counter hodscope system DPOL. 2)
Measurements were performed for excitation energies ranging from 2 to 25 Me V and for angles between
2° and 8°. This angular range corresponds to the
angular acceptance of SMART. Figure 1 shows theexcitation energy spectra of 12C at 3° and 5°. The unnatural parity states at 12.7 (1+) and 18.3 (2- ) MeV
are clearly excited as well as the natural parity states
at 4.44 (2+), 7.65 (0+) and 9.64 (3 - ) MeV. The known
broad states at 10.3 (0+) and 15.4 (2+) MeV and several unknown structures above 20 MeV are also observed. The 1+ T = 1 state at 15.1 MeV which isprominent in the (p, p') reaction is absent because of
the isoscalar nature of the (d, d') reaction.
Further analysis to separate the spin and non-spintransitions by extracting spin-flip probability is now inprogress.

1500

CD

::;.

'>
Q)

~

0

1000

en

"II)

+>

§

500

0

~

0

II)

+>

I::

Q)

::-Q)

....0

1500

CD

::;.

1000

I-<
Q)

.0

e::s 500
c:

0

0

10

15

20

30

excitation energy [MeV]Fig. 1. Excitation energy spectra of 12C at 3° and 5°(lab).

References
1) S. Ishida et al.: Phys. Lett., B314, 279 (1993); M. Morlet et al.: ibid., B247, 228 (1990); B. N. Johnson et al.:Phys. Rev., CS1, 1726 (1995).
2) S. Ishida et al.: AlP Conf. Proc., 343, 182 (1995).
3) H. Okamura et al.: ibid., p. 123.

57'

RIKEN Accel. Prog. Rep. 29 (1996)

Precise Experiment on Ii + d Scattering at 12 Me V
N. Nishimori, K. Sagara, T. Fujita, H. Akiyoshi, F. Wakamatsu, K. Maeda, H. Nakamura, and T. Nakashima*[NUCLEAR REACTION, D(n,n)D, Polarized-Neutron Beam, En = 12 MeV, Charge Symmetry Breaking.]
The analyzing power Ay(()) of nucleon-deuteron (Nd) scattering at a low energy region is very sensitive to
the P-state nucleon-nucleon (NN) interaction. Therefore the Ay (()) difference between n-d and p-d scattering is a suitable observable to study the charge symmetry breaking (CSB) in the P-state NN interaction.
To study the CSB, the following four items are necessary. (1) A rigorous 3N calculation for n-d scattering. Such calculations based on realistic NN potentials
have been extensively made in the Faddeev formalism.
(2) Precise Ay(()) data of p-d scattering. They havebeen already measured at Ep = 2- 18 Me V within an
accuracy of 1%.1,2) (3) Precise Ay(()) data of the ii-d
scattering. Existing ii-d Ay (()) data have experimental
errors of about 3%. More accurate data are necessary
to investigate CSB. Hence we planned to make an n-d
experiment with an accuracy compatible with that of ap-d experiment. (4) A rigorous 3N calculation for p-d
scattering. Coulomb force should be treated exactly.
So far such a calculation has been made only below thedeuteron breakup threshold, Ep ~ 3.3 MeV. 3)
The present n + d experiment at 12 MeV was madeat a new E7 course using d-beam from the AVF cyclotron. As described in Ref. 4, 12 MeV ii-beam wasproduced by D(d, ii) reaction at 0° using 9 MeV dbeam. The d-beam polarization (p~) was measured
throughout the experiment using 3He( d, p) reaction.
The 1 J.LA d-beam of p~ = 0.7 produced about 1 x
106 neutrons/sec of p~ = 0.6 on the target. The ii-dAy (()) was' measured simultaneously at eight angles using two targets of deuterated scintillators (NE230 and
NE213d) and four-pair (left and right) neutron counters (NE213).
The preliminary ii-d Ay (()) data are shown bysquares in Fig. 1, together with our p-d datal) obtainedat Kyushu University Tandem Accelerator Laboratory(KUTL). Though the present data agree with thoseof Triangle University National Laboratory (TUNL) ,5)
the statistical accuracy is twice improved. The accuracy of the absolute scale of the present data is about
1%, due to the fact that the p~ has been precisely
determined by a separate experiment using 4 He( ii, n)scattering at KUTL.
The differences of Ay maxima between n-d andp-d scattering are shown in Fig. 2. Our preliminary data is twice more accurate than TUNL data
at 12 MeV. The data disagree with the approximate
Coulomb calculation6 ) in which only the long-range
part of Coulomb force is taken into account. When
Department of Physics , Kyushu University

58

an exact Coulomb calculation is made at 12 MeV, adefinite conclusion will be obtained about the charge
symmetry breaking in NN force , especially in the Pwave part.

0.2

i ri+d at RUffiN:t p+d at KUTL

...

0.15

=t
I '"
.~

EN=12 MeV

<

~

0.1

...

0.05

...............•" ..,. ~ ... !

oL-~--~~--~~--~~--~~

o

20

40

60

SO

100

120

140

160

l SC

c.m. ang (deg)Fig. 1. Ay(8) of N-d scattering at 12 MeV. The squares
are the present preliminary n-d data. The crosses are
p-d data obtained a t KUTL.

I exp~ 0.025

S

~

<

C

0.02

I

~ 0.015r:='>: 0.01<j

exa~t calc.

approx. calc.

o

0.005

r

t f t t 11

present data(preliroinaJ"))oL-~~--~~~--~~~~~~

o

10

12

14

16

18

20

EN (MeV)Fig. 2. Energy dependence of Ay(8) difference between
n-d and p-d scattering at their peaks. The diamonds
are experimental data. The closed circle is the present
preliminary dat~. The square shows an exact Coulomb
calculation. The dotted line indicates an approximate
Coulomb calculation.

References
1) K . Sagara et al.: Phys. Rev. , C50 , 576 (1994) .
2) S. Shimizu et al. : ibid. , C52, 1193 (1995).
3) G. H. Berthold et al.: ibid., C41 , 1365 (1990).
4) K. Sagara et al.: RIKEN. Aceel. Prog. Rep., 28 , 121(1995).
5) C. R . Howell et al.: Few Body Systems, 2 , 19 (1987).
6) T. Takemiya: Prog. Theor. Phys. , 86, 975 (1991).

RIKEN Accel. Prog. Rep. 29 (1996)

Spin-Flip and Non-Spin-Flip Isovector Excitation Observed in the( 12 C,12N) and ( 13 C,13N) Reactions at E/A = 100-135 MeV
T. Ichihara, T. Niizeki, S. Ishida, Y. Satou, T. Uesaka, H. Okamura, K. Katoh, Y. Fuchi ,S. Kubono, M. H. Tanaka, H. Ohnuma, and M. Ishihara[charge exchange reaction e 3C ,13 N) , e 3C ,13 N) , isovector excitation, giant dipole gesonance.]e

The charge-exchange reactions of 2C, 12 N) at E/ A
= 135 MeV and (13C ,13 N) at E/A = 100 MeV havebeen studied for 9Be, 12,13 C , 24,25,26 Mg, 27 AI, 28Si,
54,56 Fe, 56,58Ni 90Z r , 120Sn and 208Pb with the spectrograph SMART.!) Cathode-readout drift chambers(CRDC)2) were used to measure the position of theanalyzed particles.
The 2C ,12 N) reactions have a selectivity of ..1S = 1
and ..1T = 1, while the 3 C, 13 N) reactions have a selectivity of ..1S = 0, 1 and ..1T = 1. Several DWBA
calculations and recent experimental study1) indicatedthat these reactions are dominantly one-step processes
in the E/ A>100 MeV region. It was reported thatthe ..1S = 0 components dominate over the ..1S = 1
components in the 3 C ,13 N) reactions at E/ A=50
MeV, while the contribution of the two-step process
affects angular distributions t o remove the diffracive
pattern. 3) The advantage in measuring the 3 C ,13N)
reaction at E/ A=100 MeV is the dominance of the
one-step process , while the disadvantage is t he possible

e

e

e

e

decreasing ratio of the ..1S = 0 to ..1S = 1 components. However, the combination of the 2C ,12 N) and( 13 C, 13 N) reactions in this higher energy domain would
be exploited to isolate the (..1S, ..1T)=(I, 1) and (0 , 1)
excitations.
Following Fig. 1 shows the preliminary sample of
Q-value spectra for 12C and 28Si targets. The broad
peak at Qt= 22 Me V (Ex=7.5 Me V) observed in the
12Ce2C,12N)12B reaction is considered to be mainly..1S = 0 giant dipole resonance (GDR) while that in
the 12C 3C, 13 N) 12B reaction is ..1S = 1 spin dipole
resonance. Strong GDR excitation was observed inthe 3C, 13 N) reaction in the 12 < A < 28 region forthe measured target nuclei. But in the heavier regionof 54 < A, the GDR is not clearly observed.
In the medium heavy nuclei such as 54,56Fe, 56,58 Ni,
90Z r , 120Sn and 208Pb, we also observed the 2nw resonances in the 3C ,13 N) reaction. The nature of these
2nw resonances is under investigation.

e

e

e

e

600

2 500
2000

4 00
1500
1000

v.: 200

v

a 500

.:
l1l

..c:
';;;-;:;
u

;::l
0

u

10

20

30

40

50

60

..c:'"
u0..........

'"

800

28 Si

C2C, 12N) 28A1

10

20

0

30

40

50

60

12CC2C, 12N) 12Bu

E/ A = 135 MeV

600

0

]2000
1500

E/ A = 135 MeV= 0° - 0 .6°

Blab

400

1000

200

500

0

0

10

20

30

40

50

60

- Ql (MeV)

Fig. 1. Sample Q-value spectra for the

0

0

10

20

30

40

50

60

- Ql (MeV)

C2C,12N) and C3 C ,13 N) react ions for 12C and 28Si targets.

References
1) T. Ichihara et al.: Phys. Lett. , B323, 278 (1994); Nucl.
Phys. , A583 , 109 (1995).

2) Y . Fuchi et al.: Nucl. Inst. Methods. Phys. Res., A362,
521 (1995).
3) C. Benat et al.: Nucl. Phys. , A555, 455 (1993).

59

RIKEN Accel. Prog. Rep. 29 (1996)

Electromagnetic Moments of 13 0
K. Matsuta, M. Tanigaki, M. Fukuda, T. Minamisono, Y. Nojiri, M. Mihara, K. Minamisono, T. Fukao,
K. Sato, Y. Matsumoto, T. Ohtsubo, S. Fukuda, S. Momota, K. Yoshida, A. Ozawa, T. Kobayashi,
1. Tanihata, J. R. Alonso,* G. F. Krebs,* and T. J. M. Symons*
NUCLEAR REACTION 16 0 + Be, E = 130 MeV/nucleon; measured (3-ray asymmetry of 13 0, nuclear
magnetic resonance; deduced magnetic moment and quadrupole moment of 13 0 ground state.
Nuclear magnetic moments of mirror nuclei provide
us with information on nuclear structure and nonnucleonic degrees of freedom in nucleus. The electric
quadrupole moment is a good probe for the proton halo
in proton rich nuclei because it depends on the radial
wave function of the valence proton. As a step towards
the systematic studies on the nuclear structure of themirror nuclei and on the proton halo in proton richnuclei, we have measured the magnetic moment andthe electric quadrupole moment of 13 0(171" = 3/2-,
T 1 / 2 = 8.6 ms) for the first time, through the combined technique of polarized radioactive nuclear beamand the ,B-NMR detection. The 13 0 is a mirror partnerof 13B, thus the present experiment completes the mirror moment measurements for the pair in the T = 3/2. quartet of A = 13.
13 0 nuclei were produced through the 130
MeV /nucleon 16 0 +9 Be collision at RIKEN Ring Cyclotron, and were separated by RIPS(RIKEN Projectile Fragment Separator). Polarization was obtainedby selecting their emission angles. Thus polarized nuclei were then slowed down by an energy degrader andwere implanted in an MgO single-crystal catcher (orTi0 2 for Q-moment measurement). The catcher wasplaced in a strong magnetic field of H 0 r-v 4 kOe (or8 kOe for Q moment) for maintaining the polarization and for NMR. Ho was monitored by proton NMR
throughout the measurement and was maintained in ahigh stability. Beta rays were detected by two sets ofscintillation counter telescopes placed above and below the catcher relative to the polarization axis. NMR
spectra were detected through the ,B-ray asymmetry
change in these counters.
An NMR spectrum was obtained as shown in Fig.
1. From the spectrum, the magnetic moment of 13 0
was obtained as lJ.Le 30)1 = (1.3891 ± 0.0003) J.LN
with a correction for the chemical shift. The sign
should be negative because the Schmidt value and all
predictions are negative. With the known magnetic
moment of the mirror partner 13B, spin expectation
value (fJ) is obtained to be 0.76, using the scalar moment relation; J.L(Tz = +3/2) + J.L(Tz = -3/2) = J+0.380(fJ). The (fJ) value of 13 0 is consistent with thesystematics from T = 1/2 pairs, making contrast withthe (fJ) value of 9C, which is unusually large (fJ) =LBL, Berkeley

60

1.44. 1 )A vQ spectrum was obtained as shown in Fig. 2.
From the vQ spectrum, the quadrupole coupling constant was obtained as leqQe 3 0 in Ti0 2 )/hl = (1900± 100) kHz, with the asymmetry parameter Tl = 0.868
known for 17 0 in Ti0 2 . 2 ) Combined with the known
leqQe 7 0 in Ti0 2 )/hl and the known Qe 7 0), the preliminary result for the quadrupole moment of 13 0 was
obtained as IQe 30) I = (33 ± 4) mb.

c3
Q)

C)

~ 2
o
~

Q)

E
E

>-

~Ol---+-±------------:l:--"""'---

2812

2816

2820

2824

2828

2832

Frequency(kHz)Fig. 1. NMR spectrum of 13 0 in MgO
5

~4
Q)

g> 3
(13

6 2
~

+-'

Q)

Eol-------I~-----'---f'--+-"T-+--

E

~-1

<!

o

20

40

60

80

100 120 140

M (kHz)Fig. 2. l/Q spectrum of 13 0 in Ti02.

References
1) K. Matsuta et al.: Nucl. Phys., A588, 153c (1995).

2) Ch. Gabathuler et al.: Proc. XVII Congress Ampere,
p. 499 (1973).

RIKEN Accel. Prog. Rep. 29 (1996)

Measurement of the Magnetic Moments of 14B and 15B Using
Projectile Fragmentation Spin Polarizationt
H. Okuno, K. Asahi , H. Ueno, H. Izumi, H. Sato, M. Adachi, T. Nakamura, T. Kubo, N. Inabe,
A. Yoshida, N. Fukunishi, T. Shimoda, H. Miyatake, N. Takahashi, W.-D. Schmidt-Ott, and M. Ishihara

1

NUCLEAR STRUCTURE, Magnetic moment of the ground state of 14B and lsB,
[ Analysis using OXBASH code.
By making use of spin polarization in the projectile
fragmentation reaction, the magnetic moments of 14 B
and lsB have been determined by the ,B-NMR measurement. The experimental procedure and the preliminary results have been reported previously.1) The
final results were obtained as J.L(14B) = (1.185±0.005)
J.LN and J.L(1sB)= (2.659 ± 0.015) J.LN, where J.LN stands
for the nuclear magnetron.
The results for 14B were compared with the PSDMK calculation 2) in Fig. l(a). The calculation depends on the energy difference C between the 81 / 2 andd S / 2 single-particle states. The standard value Cstd
is obtained by reproducing the negative parity statesof 16 0. 2) When C is taken as C = Cstd, the calculation yields a J.L value which is significantly smaller
than the experimental result , indicating the overestimation of the [np3/2, vd S/ 2]2- component. On theother hand the agreement with experiment is significantly improved when C is lowered by about 1 MeV
from the standard value Cstd. At the same time, thislowered C value better reproduces the low-lying energy
levels of 14B , as shown in Fig. l(b). These observations
suggest that the neutron 81/2 state shifts downwards
with respect to the d S / 2 state in 14B.
In Fig. 2, we compare the observed magnetic moments of odd mass B iostopes with several theoreticalpredictions. The A dependence of the A-like behavior in Fig. 2 mainly arises from those configurations
in which two neutrons in the 8d-shell couple to form
J7r = 2+ . The shell model calculations tend to underestimate the quenching effect at A = 15. This is more
apparent with the PSDWBP interaction, indicating asignificant underestimate of the neutron 2+ configurations.
Exp.

3.2

B isotopes

(a)

E 1.2

..-.. 3.0

5.

E

-S

::t 1.0

,
"

:::t.

Exp.
2.6

-2

-1

0

AM

£ - £ std (MeV)

E (MeV)
3
2

~-

2-

o
-2

-1

\~

.

o

"

......

.........

,~ ·· · ··::~o

VSM

2.4

(b)

Exp.

rSDWBP:.~y:SDMK

2.8

11

13

15

17

Mass number
Fig. 2. Comparison of experimental and theoretical magnetic moments for the odd-mass B isotopes. A filledsquare indicates the J-l value obtained in this work. The
circles represent theoretical values calculated with ashell model code OXBASH. 2)

e - £ std (MeV)
Fig. 1. Magnetic moments (a) and low-lying energy levels (b) of 14B calculated with three different valuesof the 81 / 2 single particle energy c. Cstd stands forthe value which is normally adopted for the OXBASH
calculations. 2) Experimental values are also shown.

References
1) H. Okuno et al.: RIKEN Accel. Prog. Rep., 25 , 41
(1991) .
2) B. A. Brown, A. Etchegoyen, and W. D. M. Rae:MSUCL Report , No. 524, p. 1 (1988).

Condensed from an article in Phys. Lett. , B354, 41 (1995).

61

RIKEN Accel. Prog. Rep. 29 (1996)

Electric Quadrupole Moments of Neutron-Rich Nuclei 14B and 15B
H. Izumi, K. Asahi , H. Ueno, H. Okuno, H. Sato, K. Nagata, Y. Hori, M. Adachi,
N. Aoi, A. Yoshida, G . Liu, N. Fukunishi, and M. Ishihara
NUCLEAR REACTION 93Nb (180, 14,lS B) , E/A = 70 MeV/nucleon; spin-polarized radioactive beams;[ measured ,8-NMR frequency; deduced quadrupole moments, 14B, lsB.
Spin-polarized fragments 1) 14B and lsB produced inintermediate-energy projectile fragmentation reactions
were implanted in a Mg single crystal, and the electric
quadrupole coupling constants for 14B and lsB were
determined by the ,8-NMR spectroscopy. 2) In this report, we present the results of final analysis and disscussion. In Fig. 1 the NMR spectra obtained for 14 B
and lsB are presented. In the figure the observed f3-ray
up / down ratio is plotted as a function of eqQ / h.
The coupling constants for 14B and lsB in a Mg
single crystal were determined to be leqQ(14B)/h l =106.03 ± 1.15 kHz and leqQ(1sB)/hl = 135.04 ± 2.05
kHz. Taking the ratios of the respective values tothe 12B result leqQ(12B)/h l = 46.933 ± 0.578 kHz
and using the reported values IQ(12B)1 = 13.21 ± 0.26
mb 3 ), Q-moments for 14B and lsB were determined as
IQe 4B)1 = 29.84±0.75 mb and IQeSB)1 = 38.01±1.08
mb.

1.35 ~___-__-__-__-__--=_~:=--__- _ -_ ___--_ _ -__ -_ _-__-__-_ - __- __- __--1_.2

rf offC;~ 1.30

90

100

110

120

130

eqQ/h[kHz]!

rf off

!

MK

~----

_----0....

0/~~- .. ~ WBT//~~<. Present work

0-

~

20
11

13

15

17

Fig. 2. Comparison of the experimental and theoreticalquadrupole moments for the odd-mass B isotopes. Exp:
Experimental data. MK and WBT: Onw shell model
calculations the effective interactions of PSDMK and
PSDWBT, respectively, in Ref. 5(b)-t _ _. L . - _ - - l
1.20 ' - - _ - - L . . ._ _.L..-_--L...
80
100
120
140
160
180
eqQ/h[kHz]Fig. 1. The up/down ratio of j3-ray intensities is plotted
as a function of eqQ/h, observed for (a) 14B and (b)15B implanted in a Mg crystal. The curves represent
results of the least-squares fittings of the line shape tothe data.

Condensed from the article in Phys . Lett. , B , to b epublished.

62

:c 60
!.
ca. 50mass number---- - - - - - - - - ~- --------- - - - - - - - - - - --~e 1.30~ 1.2570

30

L.......I_ _" ' - - _ - ' - - _ - ' - - _ - - ' - _ - - - - L _ - - I

80

1.35

Qe

0
(a)

1.25

The experimental Q-moment for lsB is plotted inFig. 2 together with those for the other odd-mass B isotopes. Shell-model calculations with Onw model space ,using effective charges commonly accepted in this mass
region, predict values about 40% larger than the experimental QeSB) . The large overestimation of QeSB)
by the shell model is removed if the neutron effective
charge is taken to be as small as en = 0.1. It may
suggest an interesting notion that the core polarization induced by excess neutrons in neutron-rich nuclei
is much smaller than in stable nuclei.
4TheB) sensitively reflects small admixture of
the d3 / 2 neutron configuration and, when combinedwith the previously obtained data for the magnetic
moment,4) determines reliably the ground state wave
function of 14B.

E
0
E 40

a:

1

References
1) H. Okuno et al.: Phys. Lett. , B335 , 29 (1994).
2) K. Asahi et al.: RIKEN Accel. Prog. Rep. , 27, 42 (1993).
3) T. Minamisono et al.: Phys. Rev. Lett. , 69 , 2058 (1992).
4) H. Okuno et al.: Phys. Lett. , B354, 41 (1995).
5) Shell model code OXBASH, B. A. Brown et al.: MSUCL
Report, 524, 1 (1988).

RIKEN Accel. Prog. Rep. 29 (1996)

Branching Ratios of the 14B Beta Decay
H. Ogawa, N. Aoi, K. Asahi, M. Adachi, M. Ito, H. Izumi, H. Deno, K. Nagata,* A. Yoshida,
H. Okuno, G. Liu, S. Mitsuoka, and M. Ishihara[RADIOACTIVITY 14B(,6-); measured ,6 spectrum, }3-delayed , spectrum.]
The neutron-rich nucleus 14B, in which the last neutron resides in the sd shell while the valence protons
are in the p shell, provides a usefull testing groundfor models of the effective interaction connecting thep and sd shells. In fact, Millner and Kurath 1) haveapplied their first successful model to the ,6 decay of
14B. Experimentally, the total rate of the 14B ,6 decay
is known, but its branching ratios have been measured
only for the allowed transitions to the 1 - and 3 - statesof 14C.2) In this report the observation of the unique
first-forbidden ,6-decay branch to the 14C ground stateis presented.
Fragments 14B (J7r = 2-, T 1 / 2 = 13.8 ms, Q(3 =20.64 Me V) were produced through the fragmentationof 22Ne projectiles at E/A = 110 MeV/nucleon on a
832 mg/cm 2-thick Be target. The fragments emitted
from the target were isotopically separated by the projectile fragment separator RIPS, and the beam of 14B
thus purified was stopped in an active stopper madeof a 7 mm-thick plastic scintillator located at the final focus. The,6 rays were detected with a plastic
scintillation telescope consisting of a 4 mm-thick f:l.E
counter and a 130 mm-thick E counter. Furthermore
the ,6-delayed , rays were detected by a NaI(TI) scintillation counter which was placed on the other side of
the stopper.
The energy spectrum of ,6 rays detected in coincidence with the ,6 signals from the active stopper isshown in Fig. 1. The spectrum is dominated by a major component of the allowed shape with an endpoint
energy around 14.6 MeV, which in fact is considered as
the sum of contributions from a few allowed branches
to the excited states, as shown in Fig. 2. In the portion
with E(3 > 14.6 MeV, however, contribution of anothercomponent with a much higher endpoint energy is evident. This component proves to be absent in a spectrum taken in coincidence with the I'-ray detector. The
spectrum in Fig. 1 was fitted with a theoretical function assuming that the high-endpoint component stems
from the ground state branch. The result yielded therelative intensity of the high-energy component. As amatter of fact, however, the high-energy portion should
be contaminated by the signal summing effect between
the,6 rays from the excited-state branches and their coincident ,rays. After correcting for this effect basedon the Monte Carlo simulation code EGS4,3) we tentatively obtain the branching ratio R g .s . = 1.4±O.8% for
the first-forbidden transition to the 14C ground state.
We plan to make a final measurement with a reduced

solid angle for the ,6 counter, so that the summing effect becomes negligible.
We also observed in a I'-ray spectrum taken in coincidence with the ,6 events a clear evidence for a new
branch to the 2- state. More extended analysis of the,-ray spectrum is now in progress.

8000
Q)

c

C

«I
.s= 6000

U

60

70

80

II)

C

4000

::J

0

U
2000

02030405060708090

Channel Number

Fig. 1. The f3-ray energy spectrum from 14B obtainedwith a plastic scintillation counter. The inset shows
the high-energy portion in an expanded ordinate scale.

20.64 MeV\>.... /" this work

) ...........
this work~7.34 MeV

\,.

/'\4
8.6:!:g%/\'1P ~<;l ~E> 2
I

6.73MeV'" "''t
6.09 MeV

81±9</o \

~"

+

3

1

I

~ r r

Fig. 2. The decay scheme of 14B and the energy levelsof the daughter nucleus 14C. The known f3 branchingratios of the transitions to the 1- and 3- states aretaken from Ref. 2.

References
1) D. J. Millener et al.: Nucl. Phys., A255, 315 (1975).
2) D. E. Alburger et al.: Phys. Rev., CIO, 912 (1974).
3) W. R. Nelson et al.: Stanford Linear Accelerator Center
Report, SLAC-265 (1985) .

Nippon Telegraph and Telephone Corporation

63

RIKEN Accel. Prog. Rep. 29 (1996)

Feasibility Test of Delayed Neutron Spectroscopy for
Spin-Polarized Neutron-Rich Nuclei
H. Miyatake, M. Sasaki, H. Ueno, T. Shimoda, N. Aoi,
T. Shirakura, K. Asahi , H. Izumi , H . Ogawa, G. Liu, and A. Yoshida[RADIOACTIVITY 15B(,B-), measured ,B-delayed neutron and J7r of excited states in 15C.]
Nuclei near the neutron drip-line decay into various highly excited states in daughter nuclei because of
the large Q.6-values. Since most of the final states locate higher than the neutron separation energy, the unbound neutron decays immediately after the ,B-decay.
It , therefore, is possible to identify the individual ,0transitions by detecting the delayed neutrons. Thismethod has been widely used as the "delayed particle
spectroscopy" . It is to be noted that more spectroscopic information can be deduced, if the parent nucleus is spin-polarized, as described below.
The angular distribution of the ,B-rays in an allowedtransition from the polarized nucleus is expressed withthe asymmetry parameter (A) and the polarization (P)of the parent nucleus. The A is described as a function of spins and parities of both the initial and final
states. Since the AP values for individual transitions
can be experimentally obtained, the J7r for unknown
transitions can be assigned by comparing the AP values with those for the known transitions.
In order to study the feasibility of this method, we
measured the ,B-rays from polarized 15B in coincidencewith the delayed neutrons. The polarized 15B was obtained in the same manner as that used by U eno etal.l) Fragments of 15 B emitted at angles from 1.5 to 2.5
degrees with respect to the beam axis were separated
and focused by using RIPS. The ,B-rays from 15B weredetected by a pair of ,0- ray counter telescopes placed
perpendicular to the reaction plane, and the asymmetry in ,B-decay was observed by the ,B-NMR method.
The time-of-flight of delayed neutrons was measured
by seven plastic counters (0 = 1.1 sr.) placed 1.5 m
away from the stopper to identify the final states ofthe ,B-transitions.
Polarization of 15B was determined as P= -10.7 ±
1.6% from the most intense transition to the 3.103 MeV
state in 15C. This transition is assigned by the 1.77
Me V delayed neutron peak as shown in Fig. 1. The A
values for other allowed transitions were then deduced
as listed in Table 1. Since the ground state of 15B
is known as J7r = 3/2-, possible asymmetry parameters of allowed transitions are -1.0, -0.4 and +0.6,
and the J7r values of final states are thus assigned aslisted in Table 1. These assignments are consistent

64

180
160
140
CJ)

IZ
:J

120

U

80

100

0

60
40
20
0

o

100

200

300

400

TIME (ns)Fig. 1. A part of neutron time of flight spectra with startsignals of {3-rays detected by the up-counter telescopeduring the (3-NMR off-resonance period.

Table 1. Summary of 15 B decay. The J7r values assigned
and log ft-values in this experiment are consistent withthose in Ref. 2
E~ab(MeV) E xe

5 C;MeV )

AP(%)

A(%)

J71"

J~ (%)

logft

4.82(6}6.372(20) -25 . 2(75)2.5(8)~

4.1(6}

5.05( 7)4.33(4)5.866(8)5.33( 7 }~4.657(9}93.0(8 1) -8.7(15} [ ~-]35.9( 26} -0 . 5(2}2 .6(4}3.20(1}

2"

23.3(34} 4.56(6}2"

2.82(2}4.220(3}-4 .3 (47)1.77(1)3.103(4}10.7(16}-1

0.4(4}

J71"(Ref.2}
1-

3-

2

5-

7.0(10}5. 15 ( 7 }

1-

~

"2

63.1(90} 4.34(6}

5-

"2

1-

with the reported values. 2)
In the present work, it was successfully shown thatthe delayed neutron spectroscopy combined with polarized unstable nuclei can be a unique tool to determine J7r of the highly excited states in nuclei far fromstability, where spectroscopic information is hardly accessible otherwise. It should be pointed out that thismethod can be applied not only to delayed neutrons
but also to delayed charged particles or , -rays.
As the next step of the present work, we will soon
apply this method to 17B in order to study the decay
scheme of 17B, on which only little information has
been obtained. 3 )References
1) H. Deno et al.: RIKEN Accel. Prog. Rep. , 28, 41 (1995).
2) R. Harkewics et al.: Phys. Rev. , C44, 2365 (1991).
3) G. Raimann et al.: ibid., C53, 453 (1996) .

RIKEN Accel. Prog. Rep. 29 (1996)

States in 16C Using the Transfer Reaction 15C(d,p)16C
G. Raimann, M. J. Balbes, R. N. Boyd, J. Feng, M. Fujimaki, K. Kimura, S. Kubono, T. Kobayashi,
A. Korsheninnikov, E. Yu Nikolskii, A. Ozawa, 1. Tanihata, J. Vandegriff, and K. Yoshida[NUCLEAR REACTIONS, radioactive nuclear beam, CD 2, DeSC,p) , EjA = 65 MeV.]
The inhomogeneous models of Big Bang nucleosynthesis suggest various branch points in the mass flow
to heavier elements (mass 20 and greater). We have investigated two such points recently,1,2) using /3-delayed
neutron breakup. The mass 15 branch point resultsfrom the competition between lSC /3-decay and thelSC(n,I')16C reaction. The De SC,p) 16 C reaction wasused to study the neutron capture reaction strength.
This transfer reaction is sensitive to levels in 16C , bothabove and below the lSC + n threshold. If high enoughproton energy resolution is achieved, spectroscopic factors can be calculated from the measured angular distribution of the protons.
In the experiment, a 65 A MeV lSC beam was produced from a 100 A MeV primary 22Ne beam. Two
thin plastic scintillators (1 mm) at F2 and F3 of thebeam line and TOF were used to identify lSC ions.
Each lSC ion was tracked in x and y-direction by two
MWPCs, after which it entered a scattering chamber. There it hit a CD 2-target (3 mgjcm 2 ) and subsequently left the chamber through an exit window.
Four silicon detector telescopes were mounted at backward scattering angles to detect protons (these protons
in inverse kinematics correspond to forward-scatteredprotons in the center-of-mass).
Each detector telescope consisted of two thinposition-sensitive silicon strip detectors and one thick(3 mm) silicon detector to stop the protons. The thicknesses of the ~E-detectors were 250 /.-Lm (1 mm pitch)and 400 /.-Lm (5 mm pitch). The 1 mm-pitch detectors were operated with charge division to reduce thenumber of readout signals.
The most critical issue was to achieve high enoughenergy resolution to identify states in 16C. The resolution was mostly determined by the beam TOF, thethickness of the CD 2-target, the position resolutionof the MWPCs and the energy resolution of the Edetectors. The overall uncertainty was estimated tobe between 300 and 400 ke V proton energy. U nfortunat ely, one of the two MWPCs broke during the firsthours of the experiment, and one of the timing scintillators was instead used to obtain position information
along at least one coordinate direction and with lessprecision.
An extremely strong background contribution fromparticles elastically back-scattered from the exit foil
was observed in all of the detector telescopes. In fact,
due to the proximity of the exit foil to the target andto the detector assembly, the "background" has beenfound to be so strong in the data analysis done to datethat no evidence for the proton events of interest has
been seen. More restrictive data cuts are presently
being tried to isolate the events of interest.
References
1) A. Ozawa et al.: Nucl. Phys. , A592, 244 (1995).
2) G. Raimann et al.: Phys. Rev., C53, 453 (1996).

65

RIKEN Accel. Prog. Rep. 29 (1996)

Measurement of j3-Decay Branching Ratio of 17Ne into the Groundand First Excited States of 17F
A. Ozawa, M. Fujimaki, S. Fukuda, S. Ito, T. Kobayashi, G. Kraus,
S. Momota, G. Miinzenberg, T. Suzuki, I. Tanihata, and K. Yoshida[RADIOACTIVITY 17Ne(,8+,); measured ,8 and ,8-delayed , and deduced branching ratios.]
Recently, a large radius of 17Ne compared to theones of 17F and 17N has been observed by measuring interaction cross sections at a relativistic energy. 1)
This anomalous radius can be explained by the anomalous structure of 17Ne, i.e., reversal of s-d orbitals. I) In
this assumption, the configuration of the 17Ne groundstate is abnormally given by (1Pl/2)-V(2s 1/ 2)21T andthat of the 17N ground state is normally given by(ld 5/ 2)2V(lPl/2)-1T. In order to prove this anomaly it
is crucial to observe asymmetry of ft values given by
the quantity 8 = (f t) + / (f t) - - 1. Since 8 will be zeroin complete symmetry, deviation from zero will show
the asymmetry in ground states of initial nuclei and/or
in states of final nuclei. In the present case, 17Ne and
17N decay to states in 17F and 17 0, respectively. Since
17F and 17 0 are doubly closed shell plus one nucleon
nuclei, their ground and first excited states are simple
and well known, i.e., (ld 2/ 5) and (2S 1/ 2) respectively.
Thus, 8's into the ground and first excited states are
crucial for the proof of anomaly in 17Ne. However,
8 into the ground states has not been obtained until
now due to no observation of ,8-decay branching ratioof 17Ne into the ground state in 17F. Furthermore, only
one measurement is known for the ,8-decay branchingratio of 17Ne into the first excited state of 17F. 2) Thus,
we propose to measure ,8-decay branching ratio of 17Ne
into the ground and first excited states of their daughter nuclei.
17F has only one bound excited state. Thus, if wemeasure the number of 17F produced from 17Ne, we
can obtain the sum of branching ratio into the firstand ground states. Since their half-lives are different
so much, it is possible to obtain the sum of branchingratio by measuring the ,8-decay time spectrum. Fur-

Beam coo ntelS(plastx;)

/,~

17Ne
beam

~ 71 ~ .~~--~--@~~

Ge-detectors

Plastic counter
telescopeFig. 1. Experimental setup.

66

511 keY

570

580

590

600

610

620

630

"tray energy (ch)Fig. 2. Typical ,-ray energy spectrum following the,a-decay of 17Ne.

thermore, it is also possible to measure the branchingratio into the first excited state by detecting 495 ke V ,ray emitted from the first excited state and the numberof 17Ne. Thus, subtracting the branching ratio into
first excited state from the sum, we can obtain one
into the ground state.
Experimental setup is shown in Fig. 1. A 17Ne beamof about 30 A MeV was produced by the projectile
fragmentation of a primary beam 2°Ne accelerated by
Ring Cyclotron and separated by the RIPS facility.
Major contaminant was 15 0 with the ratio of 1 by 1.
The beam was stopped in a thin plastic plate tilted by
45° to the beam axis at the front of a plastic counter
telescope and two Ge detectors. The number of implanted nuclei was counted by the scintillators locatedon beam line. These counters were also used to identify the passing nuclei by dE and TOF measurements.
A ,8-ray emitted from stopped 17Ne was detected by aplastic counter telescope consisted of dE-dE- E counters. A delayed ,-spectra emitted from the stopped
17Ne was detected by the two Ge detectors. A typicalenergy spectrum of the Ge detectors is shown in Fig. 2.
An energy peak of 495 ke V, that corresponds to the ,ray emitted from the first excited state of 17F, is clearlyvisible in the figure. Analysis is now in progress.
References
1) A. Ozawa et al.: Phys. Lett., B334, 18 (1994).
2) M. J. G. Borge et al.: ibid., B317, 25 (1993).

RIKEN Accel. Prog. Rep. 29 (1996)

Beta Decay of the Drip Line Nuclei 14Be
N. Aoi, K. Yoneda, H. Miyatake, H. Ogawa, Y. Yamamoto, E. Ideguchi,
T. Kishida, T. Nakamura, M. Notani, H. Sakurai, T. Teranishi,
S. S. Yamamoto, Y. Watanabe, A. Yoshida, and M. Ishihara[RADIOACTIVITY 14Be(,6-), measured ,6-delayed neutron, deduced logft, and deduced Ex in 14B.]
We reported in the reference 1) on the measurementof the ,6-decay of neutron drip line nucleus 14Be. In
the energy spectrum of the delayed neutron, we founda strong peak at the energy of 283(2) keV with thebranching ratio of 63(15)%. This decay is very fast
for the ,6- -decay, suggesting an unusual nuclear structure of the drip line nuclei. However, in the last experiment, we had an ambiguity in the decay energy
and in the branching ratio mainly due to the difficulties in determining the neutron detection efficiency forsuch low energy neutrons. We have carried out analternative experiment focusing on the measurementof the ,6-decay to low-lying excited states of 14B. We
measured neutrons by a newly developed detector 2)
for the neutrons of the energy between 100 keV and 1
MeV. We also detected the ,6-ray total energy and delayed 'Y rays in order to determine the relevant ,6-decay
schemes clearly.
A 14Be beam was provided by RIKEN Projectilefragment Separator (RIPS) using projectile fragmentation of 100 MeV/nucleon 18 0. The 14Be ions were
implanted into a 1 mm thick Si detector located at
the final focal plane (F3) of RIPS. The emitted ,6 rays
were detected by thin plastic scintillators placed upside and downside of the beam stopper. Behind thesedetectors, we set thick plastic scintillators in order tomeasure the total energy of ,6 rays from 14Be (Q,a of
14Be is 16.2 MeV). The energy of the neutron was measured by means of the TOF method. The ft.ight path of
the neutron was set to be 50cm. 'Y rays were detectedby Ge detectors.
The obtained neutron TOF spectrum is shown in
Fig. 1. The sharp peak around Ons corresponds to theprompt 'Y rays. The huge peak near 70 ns corresponds
to the transition mentioned above. The mean energy ofthis peak and its branching ratio are determined tentatively to be 288(6) keV and 73(15)% , respectively. The
decay curve of the events gated by this neutron peak
showed that this neutron peak was originated from thedelayed neutron of 14Be. The decay branch was determined from the maximum energy of the ,6 rays whichcoincided with the neutrons. The precise decay energy was obtained from the neutron energy taking therecoil energy into account. Then, the relevant decay
was found to be the transition to the unknown excitedstate of 14B (Ex = 1.28 MeV) and that the neutron
was emitted via the following process,
14Be ~ 14B*(1.28MeV) ----+13 B(g.s.) + n.

Using the branching ratio and decay energy obtainedby this work and the half life measured by Dufour etal.,3) the logft value is calculated to be 3.73(9) which
is one of the smallest values for ,6- -decay. From thesmalllogft value, this transition was determined to bea Gamow-Teller transition and the J7r of the final stateis 1+. It is unusual that an abnormal parity state is
located in such a low energy region (J7r of 14B(g.s.)is 2-). This state may be described as the excitationof the neutron sitting at 1pl/2 in the ground state of
14B to 281 / 2 in a different major shell. Thus, this excitation energy after being corrected for the residualinteraction between a valence neutron and a proton
is considered as the energy difference between 111P1/2
and 211S1/2. Assuming that the residual interaction between a neutron in 1I2S 1/ 2 or V1Pl/2 and a proton in
7r1p3/2 is the same for 14B and 12B, the energy difference is calculated to be around 1.5 MeV. This value
is about one half of that of the nuclei near the stability line. It is well-known that the energy of the single
particle neutron orbital of 1I2P1 / 2 decreases as the proton number decreases in N = 7 nuclei as in the caseof 11 Be. 4) The present work showed for the first timethat the same phenomenon happens in N = 9 nuclei.

1500,),-rayrn

J3 1000

En= 288(6)keVo..........
rn

~

;j

o

U

500

M

100

1M

Neutron TOF[ns]Fig. 1. TOF spectrum of neutron from 14Be. The sharp
peak around 0 ns corresponds to the prompt T ray. The
peak around 70 ns corresponds to the neutron with energy of 288(6) keY.

References
1) N. Aoi et al.: RIKEN Aeeel. Prog. Rep., 28, 38 (1995).
2) K. Yoneda et al.: This report , p. 182.
3) J. P. Dufour et al.: Phys. Lett., B206, 195 (1988).
4) I. Talmi and I. Unna: Phys. Rev. Lett., 4, 469 (1960).

67

RIKEN Accel. Prog. Rep. 29 (1996)

Measurement of the Fusion Cross Section of Neutron-Rich
Nuclei 29,31 Al
197 Au+Y. Watanabe, T. Fukuda, A. Yoshida, Y. Watanabe , Y. Mizoi, J. Nakano, M. Hirai ,H. Sakurai , H. Kobinata, Y. Pu, K. Kimura, and M. Ishihara
NUCLEAR REACTIONS 197 Au(29 AI, F) , ECM = 95-165 Mev;
197 Aue 1Al,F) , ECM = 95-165 MeV; measured fission cross section.

It is established that the fusion cross section of heavy
ions is strongly enhanced in the energy region near andbelow the Coulomb barrier as compared to the calculations based on the one-dimensional barrier penetration model. 1) This phenomenon is expected to become
more remarkable in the fusion reaction with neutronrich neuclei, because of a possibility that excess neutrons favor penetration. In order to investigate thispossibility, the systematic fusion cross section measurements of 27,29,31 Al + 197 Au were performed, measuring
fusion-fission reactions. The measurements for a stable
nucleus, 27 Al + 197 Au, and details of the detector performance have been reported elsewhere. 2) In this paper, we report the fusion cross section measurements
for two systems, 29,31 Al + 197 Au.
The neutron-rich RI beams, 29,31 AI, were produced
via a fragmentation process of 40 Ar primary beam
which impinged on a Be production target with 2.5mm thickness. The energy and intensity of the primary beam were 90 MeV/nucleon and 40 pnA. They
were then separated by the projectile fragment separator RIPS. Since the secondary beam energy was stillhigh (rv40 MeV/nucleon) , it was reduced with an Al
degrader plate with 0.98 mm and 0.85 mm thicknessfor 29,31 Al beams, respectively. The intensity of 29 Al
and 31 Al beams after the degrader was 5 x 105 cps and2 x 105 cps, respectively. The energy of 29 Al and 31 Al
beams after the degrader was 180 MeV (ranging from
160 to 232 MeV) and 170 MeV (ranging from 133 to
199 MeV), respectively. Because the energy distributions of the secondary beams were wide spread, thetime of flight (TOF) between a plastic scintillator andan MCP detector was measured in order to determine
the energy of the secondary beams one by one. The purity of the 29,31 Al beam was 99% and 94%, respectively.
The other impurities were rejected in the analysis using
the TOF and the RF timing from the cyclotron.
The Al beams impinged on a stack of ten thin Au
targets (rv 380 j.Lg/ cm 2) which was surrounded by twopairs of MWPC walls. The compound nucleus produced through a fusion reaction results in a fission andtwo fission fragments are detected by these MWPC's.
The energy and spot size of Al beams at every target were measured with PSD, separately. The fusionfission events were identified from a subset of the events

68

that hit one MWPC and had a coincident fragmentin the opposite side MWPC. By selecting the energy
loss through MWPC 's and the opening angles of two
fragments , fusion-fission events were clearly separated
from backgrounds due to the elastic scattering.
Making use of the wide energy distributions of
the secondary beams and the energy loss throughthe MWPC gases (helium 40 mbar and isobutane 10mbar) , fusion cross sections for the wide energy range
were obtained all at once. Figure 1 shows measured
fusion excitation function for the systems of 27,29,31 Al+ 197 Au. The fusion cross sections for three systems
were determined by taking into account the efficiency
of MWPC, which was estimated by a simulation calculation. The X-error bars indicate the size of binning at
the analysis which is determined so that each bin has
a sufficient yield. The V-error bars include only statistical errors. We have not yet fully estimated the error
in the absolute values , but the relative value of the fusion cross sections between three systems, 27,29,31 Al +197 Au, and among each energy is well established.
As shown in Fig. 1, the fusion cross section forneutron-rich nuclei, 29,31 AI, is enhanced below the barrier as compared to that for the stable nucleus, 27 Al.
103

102

t
CIl
CIl

o

I-.

U

100

120

140

180

Energy eM (MeV)

Fig. 1. A preliminary result of the fusion cross section.

References
1) M. Beckerman: Phys. Rep., 129, 145 (1985).
2) A. Yoshida et al.: RIKEN Accel. Prog. Rep., 27, 114(1993).

RIKEN Accel. Prog. Rep. 29 (1996)

Scattering of Radioactive Nuclei 6He and 3H by Proton
A. A. Korsheninnikov, E. Yu. Nikolskii,* T. Kobayashi, A. Ozawa, S. Fukuda, E. A. Kuzmin,*S. Momota, B. G. Novatskii,* A. A. Ogloblin,* V. Pribora,* 1. Tanihata, and K. Yoshida
NUCLEAR REACTIONS, radioactive nuclear beam, p(6He,p), p(6He,p 4He),[ EjA = 71 MeV, p(3H,p), EjA = 73.5 MeV.
Structure of such exotic extremely neutron rich nuclei at the neutron drip line as 11 Li, 11 Be, 8He wasstudied by the cross sections' measurements, fragmentation experiments and by elastic scattering, while
the related nucleus 6He was experimentally studiedmuch less. We performed an investigation of scattering
6He+p together with a study of proton scattering by
the radioactive nucleus 3H.
We used beams of 6He (71 A MeV) and 3H (73.5
A MeV) produced by the RIPS and studied collisions
6He+p and 3H+p (targets CH 2 or C) by the missing
mass method detecting recoil protons both in an inclusive way and in coincidence with other emitted particles. Protons were measured by two telescopes of solidstate detectors. Particles from a projectile breakup
were measured by a charge fragment detectors (dipole
magnet+drift chamber+plastic scintillators) and neutron walls.
The measured spectra of protons show the groundstates of 6He and 3H and the known excited state of
6He at E* = 1.8 MeV. The obtained angular distributions for elastic scattering 6He+p and 3H+p arepresented in Fig. 1 as a ratio to the Rutherford crosssection. It is seen that the experimental points correspond mainly to the nuclear scattering. Cross sections

l000~----------~~]

100 /~'"''

c,.;;.

.s

,

::s

~

,g~ 10 • 3H 74 MeV
4He72MeV• 6He71 MeV
1 0 8He66MeV
6.

15 25 35 45 55 65

1

da j dflcm are shown in Fig. 2. Both figures also show
data for scattering 8He+p, which we measured previously, and data for 4He+pl) at the center-of-mass energies close to that for 6He+p. The measured 6He+pdata is compared with the p+6Li data 2 ) at almost thesame energy of 72 Me V on the bottom of Fig. 2. Datafor scattering p+3He at 85 Me V 3) is compared withthe 3H+p data on the top of Fig. 2.

10- 1 .
1O-2.3H ,,3He
Ll 4Jie • 6tle
10- 3 o8He 0 6t.i

0:(~
15 25 35 45 55 65

e pCM , deg
Fig. 2. Cross sections for the proton scattering by 3H,
3He, 4He, 6He, 8He, and 6Li. Curves present the opticalmodel calculations.

An analysis of these proton scattering data demonstrates that (1) results for 6He and 8He are very similar
to each other and differ essentially from that for 4He reflecting that 6He and 8He have close matter radii andcontain the density components extended beyond Q_.
particle; (2) angular distributions for the proton scattering by 6He and 6Li are almost identical showing resemblance between gross-characteristics of density distributions in 6He and 6Li; and (3) results for 3H and
3He are in an intimate agreement one with another inconsistency with the belonging of these nuclei to thesame isospin doublet.

0pCM, deg
References
Fig. 1. Angular distributions in a ratio to the Rutherford
cross section for the proton scattering by 3H, 6He, 8He,
and 4He. Curves show optical model calculations.

1) S. Burzynski et al.: Phys. Rev., C39, 56 (1989).
2) R. Henneck et al.: Nucl. Phys., A571, 541 (1994).
3) L. G. Votta et al.: Phys. Rev., CIO, 520 (1974).

Kurchatov Institute, Moscow, Russia

69

RIKEN Accel. Prog. Rep. 29 (1996)

Spectroscopy of Halo Nucleus llLi
A. A. Korsheninnikov, E. Yu. Nikolskii,* T. Kobayashi, A. Ozawa, S. Fukuda, E. A. Kuzmin,*S. Momota, B. G. Novatskii,* A. A. Ogloblin,* V. Pribora,* I. Tanihata, and K. Yoshida
NUCLEAR REACTIONS, radioactive nuclear beam, p(l1Li,p), p(l1Li,p11,9,8,7Li),[ p(l1 Li,pn9,8,7Li), E/ A = 75 MeV, p(8He,p), E/ A = 66 MeV.
The neutron rich nucleus 11 Li presents one of themost exciting problems in nuclear physics. However,reflecting experimental difficulties, number of spectroscopic studies of 11 Li is restricted by two papers only
Refs. 1 and 2. In Ref. 1, a weak peak corresponding to
the 11Li state at E* = 1.2±0.1 MeV was observed. In
Ref. 2 this state was not observed, but three other excited states were reported: at E* "-'2.47, 4.85 and 6.22
MeV. We performed a new study of 11 Li by means of
scattering 11 Li+p. The key point of the experiment
was a correlational measurement of emitted particles.
We used the 11 Li beam produced by the RIPS andstudied collisions 11Li+p (targets CH 2 or C) by the
missing mass method detecting recoil protons both in
an inclusive way and in coincidence with particles fromthe breakup of 11 Li. Protons were measured by twotelescopes of solid state detectors. Particles from thedissociation of 11 Li (9,8,7Li and neutrons) were measured using a charge fragment detection system (dipole
magnet, drift chamber, and hodoscope of scintillators)
and neutron walls. Note that in this experiment westudied the 8He+p scattering also.
The inclusive spectrum of protons shows a strong
peak corresponding to the 11 Li ground state as wellas two weak peculiarities at E* "-' 4.9 and 6.4 MeV,
consistent with the results of Ref. 2. In addition, theinclusive spectrum of protons demonstrates a peak at"-' 1. 25 MeV in agreement with Ref. 1. This state of
11 Li is clearly seen with obvious statistical significancein Fig. 1, where the solid histogram presents the proton
spectrum detected in coincidence with 9Li. The samestate of 11 Li is also seen in proton spectra from theprocesses p(ll Li,p9,8,7Li) and p(l1 Li,pn 9,8,7Li). The
observed width of the state is close to the experimental
resolution.
In Fig. 1, a group on the right side from the 1.25Me V peak attracts attention. If this is one more excited state of 11 Li, it is located at a higher energy ,,-,3.0
MeV than the state at ,,-,2.47 MeV reported in Ref. 2,
and we suppose that two peaks at "-'1.25 and ,,-,3.0
MeV were not resolved in Ref. 2. One more tentative
group might be distinguished in Fig. 1 at "-'4.9 MeV.
At last, note a structure at "-'11.3 MeV in Fig. 1. It isinteresting that the corresponding peak is seen in the
spectrum measured in Ref. 2.

Kurchatov Institute, Moscow, Russia

701

All obtained data about the II Li states are summarized in Fig. 2.

...... p( 11Li,P11Li)30- p( 11Li,p9Li)

g4 0

4

8 12 16 20* ,MeV
EIILi

Fig. 1. Proton spectra from the processes indicated on
the figure. Curves show physical backgrounds.
p(llL~p._)11Be(1t-,1t-fj
T.KoOOyashi
el al [1]present
experimentlL~~11_1Dse(14c, ~14q14c,17F)
HGBdllm
etall2]6.22±O.07
4.85±O.07
2.47±O.07
1.2±0.1

0.34
L...-1-1-L-i--' ~Li+ 2n

llLi

llLi

Fig. 2. Levels of 11 Li.

References
1) T. Kobayashi: Nucl. Phys., A538, 343c (1992).
2) H. G. Bohlen et al.: Z. Phys. , A351, 7 (1995).

RIKEN Accel. Prog. Rep. 29 (1996)

Effects of Neutron Skin and Halo in 6He, 8He, and llLi
A. A. Korsheninnikov, c. A. Bertulani,* and I. Tanihata[Neutron halo, neutron skin, few-body model, eikonal calculation, proton elastic scattering.]
One of the most exciting events in nuclear physics ofrecent years is a discovery of extended neutron distributions in exotic neutron rich nuclei. Peculiarities ofdensity shape sometimes are used for classification ofextended neutron distributions into two groups, skins
and halos. During last years experimental studies in
RIKEN formed a bank of data on the proton elastic
scattering by exotic nuclei 11 Li, BHe, and 6He. We performed a comparative analysis of these data. It turns
out that proton feels valence neutrons in 6He and BHe
and does not feel them in 11 Li.
Figure 1 shows the data for scattering BHe+p,
6He+p, and 11 Li+p at different energies 1 ,2) as well as
data for p+6Li,3) which were included in our analysis,
because 6Li can be considered as an a-core plus an
extended n+p distribution. We used the eikonal approach, which has no fitting parameters and provides
connection with densities.

more similar to the dashed curves than to the dotted
ones.
Such a distinction of 11 Li from 8He and 6He remains
at high energy pro tori scattering (Fig. 2). Calculationsfor 11 Li+p at 800 A MeV show that the solid curve(the "realistic" density) is close to the dashed curve(the "core-like" density) and both of them differ fromthe dotted curve. In the scattering by 6He and 8He atangles::; 10° the solid curves are close to the dotted
ones and differ from the dashed curves. At larger angles all three curves have distinctive behaviors (inserts
in Fig. 2) showing a possibility of extracting detailed
information about densities of BHe and 6He.
104fT"'---.....................

103
102
~

~ 101
B

~ 100
"0

10- 1
10-2

~

~

i

"0

100
10- 1 73 Me
10- 2

"""

"""

"

Fig. 1. Proton scattering by 8,6He, 6,llLi.

Calculations with the "realistic" densities, whichcorrespond to the experimental matter radius, Rmat,of B,6He or 6,11 Li and contain the skin or the halo, areshown in Fig. 1 by solid curves and are in a good agreement with all data. Calculations with the "non-halo"densities, which correspond to Rmat, but neglect a difference between proton and neutron radii, are shownby dotted curves. For all cases except for 11 Li thesecurves are close to the solid curves. The dashed curves,which correspond to the "core-like" densities where theskin or the halo is neglected and Rmat is replaced by
the radius of the core, differ drastically from the experimental data for 6He, BHe and 6Li. Such regularities
are different for scattering 11 Li+p: the solid curves are

Fig. 2. Calculations of high energy proton scattering by
11 Li, 6,8He.

Summarizing, (1) the scattering of 6,BHe and 6Li at
low energies (and at small angles at high energies) is
not sensitive to a difference in the neutron and proton
distributions, but it is sensitive to the matter radius ofthese nuclei and feels the density extension beyond thea-particle; and (2) on the contrary, the elastic scattering 11 Li+p is mainly determined by the proton scattering on the 9Li-core and is not sensitive to the neutron
halo extended beyond the 9Li-core. These results forma basis for distinction between the neutron skin (6,BHe)
and the neutron halo (11 Li).
References
1) A. Korsheninnikov et al.: Phys. Lett., B343, 53 (1995);
ibid., B316, 38 (1993); to be published in Phys. Rev.,
C53, (1996).
2) C. B. Moon et al.: ibid., B297, 39 (1992).
3) R. Henneck et al.: Nucl. Phys., A571, 541 (1994).

U niversidade Federal do Rio de Janeiro, Brazil

71

RIKEN Accel. Prog. Rep. 29 (1996)

Charge Exchange Reactions of 11 Li
T. Teranishi, S. Shimoura, Y. Ando, M. Hirai, M. Ishihara, N. Iwasa, T. Kikuchi,
S. Moriya, T. Motobayashi, H. Murakami , T. Nakamura, T. Nishio, H. Sakurai,
T. Uchibori, Y. Watanabe, and Y. Yanagisawa[NUCLEAR REACTIONS: p(l1Li,l1Be*)n, d(l1Li,l1Be*)nn, 63 MeV/nucleon.]
We have studied Fermi and Gamow-Tellar (GT)transitions of the halo nucleus 11 Li by the charge exchange reactions p(l1 Li, 11 Be*)n and d(l1 Li, 11 Be*)nn.
One of our interests is to study the isobaric analogue
state (lAS) of 11 Li , which has never been observed.
The lAS 's for stable nuclei have been studied well so
far by (p,n) reactions. They have narrow widths, andtheir Coulomb displacement energies are well approximated by the following expression: 1)

6.Ec = 1.44(Z + 0.5)/A 1 / 3 + 1.13 [MeV].

(1)

In the case of the 11 Li nucleus, the lAS may have different properties from those of stable nuclei, becauseof the unusual nucleon distribution in the 11 Li nucleus.
We utilized inverse kinematics reactions of(p,n)- and (d ,2n)-type, namely p(l1Li,l1Be*)n andd(l1 Li, 11 Be* )nn, since 11 Li is provided as a secondary
beam. Proton and deuteron targets were used to distinguish the type of the transition (Fermi or GT).
Fermi and G T transitions are allowed for the proton
target. On the other hand , only GT transition is allowed for the deuteron target provided that the relative
energy between two neutrons in the final state is small.
Most of the final states 11 Be* are particle unbound anddecay into more than two particles. For the lAS , only
the decay channel 9Li+p+n is allowed by the isospin
selection rule, namely the isospin of the lAS (T = 5/2)
can be constructed from the 9Li+p+n (T = 3/2, 1/2,
and 1/2) combination only. The excitation energy of
11 Be* was determined by reconstructing the invariant
mass from momentum vectors of outgoing particles.
Since the outgoing particles are kinematically focused
due to the characteristics of inverse kinematics , relatively high efficiency of the coincidence detection isachieved.
A 63 Me V / nucleon 11 Li beam from the RIPS facility at RIKEN was used to bombard (CH 2 )n and(CD 2 )n targets (200 mg/cm 2 ). The final state particles
emitted from 11 Be* were detected by 6.E- and E- hodoscopes which consisted of 13 and 33 plastic scintillators, respectively. Charged particles were identified by
combining 6.E-, E- signals with time-of-flight (TOF)
information between the target and hodoscopes. Particles which produced signals in E-hodoscope (12 cm
thick), but not in 6.E-hodoscope (0.5 cm thick), wereidentified as neutrons. The momentum vector of a par-72

ticle was obtained by the TOF and position information of the hodoscopes. The invariant masses of the
final states 11 Be* were constructed from the momentum vectors. Carbon-target runs were also performed
in order to estimate the background contribution.
The relative energy spectra of the 9Li+p+n channel
with Hand D targets are shown in Fig. 1. A peak at
E(9Li+p+n) ",,1.0 MeV (Ex (11 Be) ",,21.2 MeV) was
found in the spectrum for the H target , while no sharp
peak was found for the D target. Thus , the peak canbe regarded as the lAS of 11 Li. The Coulomb displacement energy 6.Ec is about 1.3 MeV, consistent with avalue 6.Ec = 1.1 MeV of the formula (1). Taking into
account the resolving power of the relative energy inthe present detector system, the natural width of thepeak was deduced to be about 0.5 MeV (FWHM). The
width is somewhat larger than those of lAS 's for stable nuclei. Two theoretical predictions 2 ,3) show thatthe width is sensitive to the configuration of the valence neutrons in 11 Li. The scattering angle distributions of 11 Be* for 9Li+p+n channel with Hand D
targets indicate that the dominant component of theangular momentum transfer 6.[ is zero. Analysis forchannels related to the GT transitions (9Li+d, 8Li+t ,6He+ 4 He+n, and so on) is now in progress.
d( l1Li , ~i +p+n)nnp( llLi, 9Li + p + n )n
6

>5

>5

~4

~
4
.0

III

III

.0

S3

S3

~ 2

~ 2

"b

"b

"CJ

"CJ

2

4

6

6

E('1.i+ p +n) [MeV]

10

2

4

6

B

10

E('1.i+ p +n) [MeV]Fig. 1. Relative energy spectra for 9Li+p+n channel withH (left) and D (right) targets.

References
1) J. D. Anderson et al.: Phys. Rev. , 138, B615 (1965).
2) Y. Suzuki and K. Yabana: Phys. Lett. , B272, 173(1992).
3) M. V. Zhukov et al.: preprint NORDITA-95/32 N.

RIKEN Accel. Prog. Rep. 29 (1996)

Coulomb Dissociation of 8B
T. Kikuchi, T. Motobayashi, N. Iwasa,*l S. Moriya, Y. Ando, H. Murakami, S. Shimoura,
T. Teranishi, Y. Yanagisawa, T. Nishio, T. Uchibori, T. Nakamura, M. Hirai, Y. Watanabe,
H. Sakurai, S. Kubono, M. Gai, R. H. France III, *2 K. 1. Hahn, * C. Michotte, *3
P. Lipnik,*3 and T. Delbar*3

The first experiment of Coulomb dissociation of 8Bl)
showed the usefulness of the Coulomb dissociation
method in studying the 7Be(p, 'Y )8B reaction at low
energies. At the same time, it showed some problemsof this method and one of the most important was in
the estimation of the multipolarity.
For the Coulomb dissociation of 8B, E1 excitation
is dominant and some mixture of E2 excitation is possible. For the setup of the first experiment, E2 contribution was estimated at 15% of the E1 amplitude
at 1 Me V using a theoretical calculation of the crosssection for the 7Be(p, 'Y )8B reaction at low energies. 2)
However, we could not distinguish the E2 excitationfrom the E1 experimentally.
Since the E2 excitation becomes dominant at large
angles, it is important to cover a wide angular range todistinguish E2 from E1. Recently, we performed thesecond experiment with a new setup covering a wider
angular range. Additionally, we improved energy andangular resolution in the setup.
The experiment was performed at RIKEN using
RIPS. A 8B radioactive beam of 52 MeV/nucleon wasused with a 208Pb target of 50 mg/cm 2. The typicalintensity of the beam was 2x 104 /sec. The dissociation products, proton and 7Be, were measured by aplastic scintillator hodoscope placed at 3.1 m downstream from the target. A helium bag was inserted
between the target and the hodoscope to reduce thedissociation in the air. The hodoscope covers the areaof 1 x 1 m 2 and it consists of 13 strips of DoE counters (5 mm thick) and 18 strips of E counters (6 cm
thick). Surrounding the target position, 56 NaI (Tl)scintillators were located to detect the 'Y rays from theexcited 7Be nuclei, which are associated with anotherpossible channel of the dissociation process. Hitting
positions in the hodoscope and the TOF between thetarget and the hodoscope were measured. From thisinformation, we constructed the p-7Be relative energy
and the scattering angle of the p-7Be center-of-mass.
The experimental results for the relative energy
spectrum and angular distribution are shown in Fig.
1. The solid curves show the results of Monte-Carlo

*1

*2
*3

simulation calculations with a constant S17 =22 eV-b
assuming pure El transition. Note that the calculations take account of the detector effeciency. The angular distribution is integrated over the energy rangeof E rel =0.5- 3.0 MeV. Both distributions show good
agreement with the simulation results. Especially, theangular distribution at large angles suggests that the
mixture of E2 transition is rather small. Further analysis is now in progress.

300>- 250Q)~..........
.0

200

S 150

~

..........

100

't3

50

't3

t>

\j,I

0.5

1

1.5
Erel(MeV)

2

2.5

3

Fig. 1. (a) Measured p-7Be relative energy spectrum. (b)Yields plotted versus angles of the p_7Be center-of-massthat are integrated over the energy range Erel=0.5-3.0
MeV. The solid curves show the results of Monte-Carlosimulation.

References
1) T. Motobayashi et al.: Phys. Rev. Lett., 73 , 2680 (1994).
2) K. H. Kim et al.: Phys. Rev., C35, 363 (1987).

GSI, Germany
Department of Physics, Yale University, U.S.A.
Institut de Physizue Nucleaire, Universite Catholique deLouvain, Belgium

73

RIKEN Accel. Prog. Rep. 29 (1996)

Coulomb Dissociation Reaction and Neutron-Neutron
Correlation in 11 Lit
S. Shimoura, T. Nakamura, M. Ishihara, N. Inabe, T. Kobayashi, T. Kubo, R. H. Siemssen,*
1. Tanihata, and Y. Watanabe
NUCLEAR REACTIONS heavy-ion collision, radioactive beam, Coulomb dissociation,[ Pb(l1 Li, 9Li+2n)X, soft E1 mode.
We have performed a full exclusive measurement of the Coulomb dissociation reaction, Pb(ll Li,
9Li + 2n)X, at an incident energy of 43 A MeV. An excitation energy spectrum of 11 Li deduced from the invariant mass of the three body system, 9Li + 2n, shows
a prominent peak around 1 MeV with a large tail towards higher excitation energies (Fig. 1). The relative
energy spectrum between the observed two neutrons
shows a peak with very small energy below 100 keV,which is much smaller than the excitation energy of
11 Li * (Fig. 2).
These characteristics are well reproduced by a direct breakup model with an extended-:? 200'2~..6~ 150

to..........

s:: 100
I
s::

r£I
"0

'-b---

50

"0

a

0

0.2

0.4

0.6

0.8

E n - n (MeV)
Fig. 2. Relative energy spectrum of the observed twoneutrons.

150
125

....,

'§ 100
.0

r...
~

75

..

~

'0
-..........

50

0

"0

/.J

25

q,

a

a

2

3

Ex (MeV)45Fig. 1. Excitation energy spectrum of 11 Li spectrum.
Solid lines represent the prediction of the direct up
model.

Condensed from the article in Phys. Lett., B348, 29 (1995)
KVI, University of Groningen, The Netherlands

74

di-neutron cluster model, where the ground state of
the 11 Li nucleus consists of the core and the di-neutron
with a distributed mass spectrum. Taking into accountthe final state interaction between the two halo neutrons, the rms of the neutrons is deduced to be 5.1
fm, whereas the rms of the distance between the twoneutrons is 7.0 fm. The correlation between the halo
neutrons, (Tl' T2)(rr) (r~) is deduced to be close
to zero, where Tl (f2) denotes the radial vector of eachneutron with respect to the c.m. of the 11 Li nucleus.
In terms of the shell-model description this result iscompatible with the situation where the two neutrons
move almost independently or the correlated two particles are attributed to a fairly pure configuration [j2]J=owith a particular j-value.

RIKEN Accel. Prog. Rep. 29 (1996)

Coulomb Excitation of a Halo Nucleus 11 Be
T. Nakamura, T. Motobayashi, H. Sakurai, S. Shimoura, T. Teranishi, Y. Yanagisawa, and M. Ishihara[NUCLEAR REACTION 11 Be + 208Pb, E(11 Be) = 64 MeV /u, Coulomb excitation neutron halo, B(E1).]
Coulomb excitation reaction using an intermediate
energy radioactive nuclear beam has been proven to bea useful tool in investigating the structures of nuclei farfrom the stability. One advantage is that the reaction
mechanism is comparatively well understood. Extraction of the relevant reduced matrix element may bemade by the equivalent photon method based on thefirst order perturbation or by a simple coupled-channel
calculation. However, the validity of these methods isin some cases questioned due to the ambiguities causedby the higher order excitations or by the nuclear excitation contribution.
The present experiment investigates the 11 Be
Coulomb excitation to its first excited state (E1:
1/2+ ~ 1/2-, Ex = 320 keV) in order to performa rigorous test of our understanding of the Coulomb
excitation process. Its inverse transition was formerly
studied by measuring the life time,1) so that we may
compare the deduced B(E1) strength with that obtained in the life-time measurement. On the other
hand, the previous result on the Coulomb excitationof 11 Be at GANIL 2) provided a result contradictory to
the life-time measurement. It is, thus, of importance
to examine the relevant Coulomb excitation via an independent experiment.
The experiment was performed at RIKEN Ring Cyclotron. A secondary 11 Be beam was almost purely(over 98%) separated via the fragment separator RIPS.
The beam with a mean energy of 64 MeV /u impinged
upon a 208Pb target with thickness of 350 mg/cm 2.
The Coulomb excitation cross section was obtatined bymeasureing the de-exciting, rays in coincidence withthe scattered 11 Be particles. The, rays were detectedwith 54 NaI(TI) plastic scintillators, each of which isof rectangular shape with size of 6 x 6 x 12 cm 3 , surrounding the target from 66 to 154 degrees in the laboratory frame. The inelastically scattered 11 Be particles were detected and identified with a ~E - E plastic
scintillator telescope located 3.1 m downstream of thetarget. The maximum scattering angle detectable withthe telescope was 9.0 degree, which is much larger than
the grazing angle 3.7 degree for the relevant reaction.
Figure 1 shows the obtained ,-ray energy spectrum in the 11 Be + 208Pb inelastic scattering, where
the Doppler shifts caused by the source velocity (v =0.35 c) were corrected according to the angle of eachdetector. Accidental coincidence events were subtracted in Fig. 1 by using the data obtained by setting
a gate at the region beside the true-coincidence peakin the timing spectrum of , rays. As clearly seen in the
figure, only one photo-peak at 320 KeV corresponding

500

~

.:.:
o

400

.::::. 300....,rJl

§ 200
o

U

100

200

400

600

BOO

1000

E"1 [KeV]

Fig. 1. De-excitation "(-ray energy spectrum in the inelastic scattering of 11 Be + 208Pb measured by NaI(Tl)counters. Doppler shifts are corrected in the spectrum.

to the 1/2- ~ 1/2+ transition was observed. Since
the 320 Ke V state is the only one bound state of the
11 Be nucleus, this de-excitation , rays have to be fed
only via the excitation of the 11 Be ground state to the
1/2- state. The excitation cross section was obtained
to be 302 ± 8 (statiscal) ±30 (systematic) mb.
Utilizing the equivalent photon method, the B(E1)value for the relevant excitation was extracted. As acutoff impact parameter, we adopted 12.3 fm, which
was determined from the impact parameter dependence observed in the Coulomb dissociation of 11 Be. 3 )The obtained B(E1) amounts to 0.099 ± 0.010 e2fm 2.
We also analyzed the angular distribution of scattered 11 Be particles. The distribution was comparedwith the calculated distribution obtained by a coupled channel calculation code ECIS incorporating thefinite energy- and angular spreads of the beam, angular resolution of the detector, and the multiple
scattering effect by a Monte-Carlo simulation. The
best fit deformation parameter f3 was obtained to be
0.124 ± 0.007(statistical) ±0.007 (systematic), whichcorresponds to B(E1) = 0.100 ± 0.017 e 2fm 2.
The present results in both analysis procedures arein good agreement with the value 0.116 ± 0.012 e 2fm 2
obtained from the life-time measurement. This factdemonstrates the validity of the Coulomb excitation atintermediate energies. The higher order effects and nuclear excitation contribution were found to be as small
as about 10%, if any.
References
1) D. J. Millener et al.: Phys. Rev., C28, 497 (1983).

2) R. Anne et al.: Z. Phys. A, in press.
3) T. Nakamura et al.: Phys. Lett., B331, 296 (1994).
75

RIKEN Accel. Prog. Rep. 29 (1996)

Coulomb Excitation of 56Ni
Y. Yanagisawa, T. Motobayashi , s. Shimoura, K. Ieki, Y. Ando, T. Nishio,s. Moriya, Y. Iwata, T. Kikuchi, T. Uchibori, T. Nakamura, M. Notani ,N. Aoi, T. Teranishi, H. Sakurai, M. Ishihara, and J. Peter*[208Pb( 56 Ni, 56 Ni ,)208Pb , Coulomb excitation, deduced B(E2).J
Recently, Coulomb exci tation at several tens
MeV /nucleon has been studied using unstable beam. 1)
From the spectroscopic view point , the electromagnetic excitations are properties useful in studying basic structures of the nuclei. We studied the Coulomb
excitation of double magic nucleus 56Ni using a 70.7
MeV /nucleon 56Ni beam provided by the RIPS facility of the Riken Ring Cycrotron. A 208Pb target of
350 mg/ cm 2 thickness was set in the air at the focal
point of the RIPS, and was bombarded by a 56Ni beamwith 500 S - 1 intensity.
Scattered 56Ni nuclei were detected by a counter
telescope placed at 15 cm from the target after passing through a 25 J.-Lm thick mylar window. The telescope consisted of two surface barrier silicon detectors.
The first detector has a 60 x 60 mm 2 effective area and
400 J.-Lm thickness, and the second is of octagon shapewith 36 cm 2 effective area and 1 mm thickness. The
detected charged particle was identified by the ~E- E
method. The excitation to the 2+ state of 56Ni was
identified by measuring the ,-:ray deexcitation of the2+ state in coincidence with the scattered 56Ni particles.
Sixty NaI(TI) scintillators were placed around thetarget to detect the ., rays. Each scintillator crystal isof rectangular shape with size 6 x 6 x 12 cm 3 coupledwith a 5.1 cm ¢ photomultiplier tube. Their energy
resolution was typically 7.5% for the 662 keV , ray. A
0.5 mm thick plastic scintillator was placed in front of
the silicon detector telescope to obtain a timing signal providing the coincidence condition with the ,-ray
detector.
Figure 1 shows the ,-ray spectrum for the
56Ni +208 Pb inelastic scattering after the doppler shiftcorrection. As clearly seen in Fig. 1, a full-energy peakat 2.7 MeV corresponding to the 2+ ~ 0+ transition
was observed. The excitation cross section was extracted with photo-peak efficiency calculated by a simulation code GEANT. The calculated spectrum was ingood agreement with the experimental one around theLaboratorie de Physique Corpusculaire,
ISMRA and Universite de Caen, France

76

IN2P3-CNRS ,

200

150

>

Q)

~

0
0

.....
"""'
- 100
CIl
.....
Q

.,a

c..>

50

o

1000

1500

2000

2500

3000

Energy [keY]
Fig. 1. Doppler-corrected spectrum for ,-ray energy
emitted from the 56Ni + 208Pb inelastic scattering at
E i n = 70.7 MeV /nudeon incident energy. The histogram shows the simulation result. (see the text)

peak. (See, Fig. 1)
An experimental deformation parameter f3c was extracted by comparing the predicted cross section obtained by a coupled channel calculation code ECIS
with the experimental one. Since the parameter f3c isdirectly related to B (E2) , a preliminary B (E2) value
for the 56Ni 2+ excitation was obtained. The result ,B(E2 : 0+ ~ 2+ ) = 510 ± 100 e 2fm4 , agrees with thevalues deduced from an analysis of the 56Ni + p inelastic scattering 2) within errors. Note that the error
quoted above contains systematic uncertainties. An
effort to reduce the uncertainties is in progress.

References
1) T. Motobayashi et al: Phys. Lett. , B 346 , 9 (1995).
2) G. Kraus et al: Phys. Rev. Lett. , B264, 1773 (1994).

RIKEN Accel. Prog. Rep. 29 (1996)

Neutron Skin of Na Isotopes Studied via
Their Interaction Cross Sections
T. Suzuki, H. Geissel ,* O. Bochkarev,** L. Chulkov,** M. Golovkov,** D. Hirata , H. Irnich,* Z. Janas,*
H. Keller,* T. Kobayashi, G. Kraus,* G. Miinzenberg,* S. Neumaier,* F. Nickel,* A. Ozawa,
A. Piechaczeck,* E. Roeckl ,* W. Schwab,* K. Suemmerer,* K. Yoshida, and 1. Tanihata
In order to obtain more direct information concerning the neutron skin, we measured a I, determined the effective root-mean-square (rms) matterradii (rm == (r~)1/2) , and deduced the rms neutronradii (r n == (r~) 1/2) for a chain of N a isotopes in themass range from A = 20 to 32 comparing with the rms
charge radii (r e == (r~) 1/2) determined by isotope-shiftmeasurements. 1)
The experiment 2) was performed at the projectile
FRagment Separator (FRS) facility at GS1. We applied
the optical limit of the Glauber model to obtain theeffective rms radii (rk)' Suffix k denotes p(c) for the
proton (charge) distribution and n( m) for the neutron(matter) distribution, respectively. As for the formof the density distribution of projectiles, we used the
Fermi-type distribution for both protons and neutrons.
Namely, the density pk (r) at a distance r is given by
pk(r) = pk(O)/[l + exp((r - Rk)/d k )]where the parameter Rk is the half-density radius anddk is the surface diffuseness. Suffix k indicates a protonor neutron. It was found that the Fourier transformation of the longitudinal form factor (IFL(q) I), measured
in elastic electron scattering on 23Na,3) could be wellfitted by the above equation for r < 4.0 fm , while thecovered range of the momentum transfer (q) was limited as 0.25 < q < 2 fm -1. The fitted parameters
for the proton distribution in 23Na(Rp = 3.137 fm ,d p = 0.564 fm) gave the value rp = 2.829 fm, which
agrees with rp obtained from the experimental valueof re. There are four parameters (Rp, Rn, dp, and dn )in these distributions. On the other hand, only twoquantities were experimentally determined. Therefore, we have to assume further conditions between
the parameters in order to deduce the density distribution or the effective rms radius. To see the sensitivity of the assumption to the final results, we applied
two extreme assumptions: a) Rn(ANa) = r oN 1 / 3, andRp(ANa) = Rn(23Na) = 3.137 fm (the value obtainedfor 23Na) and b) dp(ANa) = dn(ANa) = 0.564 fm (thevalue obtained at 23Na). In assumption a) , the densities are considered to change only due to changes
in the surface diffuseness, except for the N 1 / 3 dependence of Rn. On the other hand, all changes are put
into changes of Rk in assumption b). We consider thata realistic change would be in between these two assumptions.
In the following we restrict ourselves to a discussion
based on the result from case b) , however, the discussion does not differ if we use case a). In Fig. 1 ~R
is plotted against the difference between the neutron
and proton separation energy or the Fermi-energy difference (Sp - Sn). For nuclei having an even neutron
number, we took Sn as half of the two-neutron separation energy. It can be seen that ~R has a strong
correlation with Sp - Sn, for the first time. Such a correlation has been predicted by the RMF model,4) andis shown by the shadow in Fig. 1. The experimental
data agree well with the prediction.

o.

.....

.E

o.
.L.,...

, ...e-o.~~--~

-15

__

~~

__ __

o
Sp.S,.

~

~~

___

15
(MeV)

Fig. 1. The two-dimensional plot of the difference between the proton separation energy and that of a neutron (Sp - Sn) versus the thickness of the neutron skin(Tn - Tp). The corresponding mass number is indicatedat each data point. The shaded area shows the calculated correlation for various isotopes ranging from helium up to lead.

References
1) G. Huber et al.: Phys. Rev., C18 , 2342 (1978).
2) T. Suzuki et al.: Phys. Rev. Lett., 75 , 3241 (1995).
3) R. P. Singhal et al.: J. Phys., G8, 1059 (1982) .
4) 1. Tanihata et al.: Phys. Lett., B289, 261 (1992) .

Gesellschaft fur Schwerionenforschung, Germany
Kurchatov Institute, Russia

77

RIKEN Accel. Prog. Rep. 29 (1996)

Interaction Cross Sections and Radii of Light Nuclei
A. Ozawa, T. Kobayashi, Y. Sugahara, I. Tanihata, O. Yamakawa,*1
K. Ornata, K. Sugimoto,*2 D. Olson,*3 W. Christie,*3 and H. Wieman*3
NUCLEAR REACTIONS Be,C,AI,( 1S B, 1SB)X, Be,C,AI,(9C, 9C)X, Be,C,AI,eoC, lOC)X,
Be,C,AI,esC, 1SC)X, Be,C,AI,e 3N, 13N)X, Be,C,AI,e 30, 130)X, Be,C,AI,e 40, 140)X,
Be,C,AI,esO, 1S0)X, EjA = 730 MeV; measured interaction cross sections (TI, deduced[
root mean square radii.
The recent development of radioactive nuclear
beams provides new measurements of the radii of unstable light nuclei at the relativistic energy. 1-6) In these
papers, isotope, isospin, and energy dependence of theradii are shown. 3,4,6) Furthermore, combining the recent development in measurements of quadrupole moments, some interesting systematics was shown. S) To
extend the stream of the study, we have to know theunknown radii of other light nuclei.
The secondary beams of radioactive isotopes 1sB,
9C, lOC, 1SC, 13N, 13 0, 14 0, and 1S0 were produced
through the projectile fragmentation of 12C (for 9C),
18 0 (for 1sB and 13N) 20Ne (for lOC 1SC 13 0 and,'"
14 0), and 22Ne (for 1S0)
primary beams (800 A MeV)
accelerated by the Bevalac at the Lawrence Berkeley
Laboratory. The secondary beams produced in a Be
target were separated by their rigidity using a beamtransport line, and the interaction cross section ((TI)
was measured by means of a transmission method with
Be, C, and Al targets at a mean energy of around 730
A MeV, using a large acceptance spectrometer (HISS)
as described in previous papers. 1,2) The 1sB values inthis work are consistent with the previous values 3) but
have much better accuracy. The effective root-meansquare (RMS) radii of the nucleon distribution havebeen deduced from the (TI'S using Glauber model calculations, of which the details are described in Ref. 2.
The RMS radii were deduced from the (TI'S by use of theHarmonic-Oscillator (HO) type density distributions.
Figure 1 shows the effective RMS matter radii asa function of the isotopes in B, C, N, and O. In the
figure, the RMS matter radii calculated from the observed RMS charge radii are also shown for the stable
nuclei. In the calculation, we used HO type density
distributions and determined the RMS matter radii toreproduce the observed RMS charge radii. In the C,
N, and 0 isotopes, the radii of the most proton-richnuclei (9C, 12N, 13 0) are larger than the ones of theirneighbors. The observed global tendency of isotope
dependence can be quantitatively reproduced by relativistic mean field (RMF) calculations.

*1
*2

*3
78

Fukui Prefectual University
Osaka University
LBL, Berkeley, U.S.A.

1

3.2 ,....,....,~.....,..........."'P"T'"............,....---,...............,....~

3.0

2.8
2.6

2.4
2.2

2.6

C.lsotope

2.4

~

2.2

E

~

C(

2.8
2.6
2.4
2.2

2.8
2.6
2.4

2.2 &.....1......................................."""-.................................,
8
10 12
14
16 18 20
A

Fig. 1. The effective RMS matter radii (R~s) for B, C, N
and 0 isotopes. Closed circles are data points obtainedin the present work, open circles are from Ref. 3, open
squares from Ref. 4, open rhombuses from Ref. 5, andthe lines are calculated radii by RMF. Open triangles
are the radii calculated from the observed RMS charge
radii.

References
1) I. Tanihata et al.: Phys. Lett., B160, 380 (1985).
2) I. Tanihata et al.: Phys. Rev. Lett., 55, 2676 (1985).
3) 1. Tanihata et al.: Phys. Lett., B206, 592 (1988).
4) A. Ozawa et al.: ibid., B334, 18 (1994).
5) A. Ozawa et al.: Nucl. Phys., A583, 807 (1995).
6) T. Suzuki et al.: Phys. Rev. Lett., 75, 3241 (1995).

RIKEN Accel. Prog. Rep. 29 (1996)

Structure of lOLi Studied by Pion Double Charge
Exchange Reaction lOBe 1r-, 1r+) l OLi
T. Kobayashi, K. Tanaka,* D. Smith,** R. Ivie,** P. Hui,** and T. Fortune**
NUCLEAR REACTIONS lOB(7r- , 7r+) , E(7r-) = 160 MeV, deduded positions of[ ground and excited states.
The structure of 11 Li, which is known to have a neutron halo, is most commonly treated as a 3-body system of 9Li + n + n by various theoretical groups. In
this case, the interaction of 9Li + n, i.e., lOLi resonance, becomes important. There were several experiments on lOLi in the past, however, results are notconsistent with each other. In the isotone with a neutron number 7, the relative position of vPl/2 and V2S 1 / 2
orbitals is becoming closer from oxygen to boron, andthe V2S 1 / 2 orbital becomes a ground state in 11 Be. In
9He, however, a VPl/2 state becomes again a groundstate. Therefore, it is an interesting question whether
the ground state of lOLi, which is located between 9He
and 11 Be, is a neutron p-wave or s-wave state.
The measurement was performed using the EPICS
spectrometer at LAMPF. The pion-induced double
charge exchange reaction, lOB(7r-, 7r+)lOLi, was measured at a laboratory angle of 5° and at an incident
energy of 164 Me V. The spectrum is shown in Fig.
1. The resolution in the Q-value spectrum was testedby the elastic scattering, lOB(7r-, 7r-)lOB, and it was
about 0.4 MeV FWHM. It can be seen that there are
structures near the threshold and around 5 Me V.

ting was repeated taking into account the width of thestates. The width of the first 2 peaks is about 0.4 MeV,
and that of the second 2 peaks is about 0.8 MeV. Thesewidths are consistent with p-wave and d-wave, respectively.
For a possible s-wave resonance near the threshold,a small amount of deviation fron the fitting is observedon the left side of the peak if the peak is fitted as a
doublet. The fitting is repeated assuming a triplet.
The energy of the 1st peak, corresponding to the possible s-wave resonance, is very close to the threshold:about 0.02 MeV. But the existence of this peak is notconclusive since there is no appreciable decrease of chisquare in the fitting. Observed states are summarized
in Fig. 2.
5.6 MeV

4.0

60

0.96
0.37

108(x-,x+) IOU
50

>'

~

-

T lt=1 64MeV

~
c

-0

"b

- ~=-~.~g,?-----

11 U

10u

30

Fig. 2. States in lOLi from the present measurement.
20

N
-0

10

0

0

5

10

15

-Sn [MeV]

If the structure near the threshold is analyzed assuming a single peak, the width of the peak becomes
0.8 MeV. It is too narrow for an s-wave, and too wide
for a p-wave. The peak was then fitted assuming adoublet using an elastic line shape, and peaks at 0.33,
0.93, 3.98, and 5.56 MeV were found. Then the fit**

--

40

ci

.=.

--

- - - - - 0 . 3 MeV

0 1ab=5 O

';::-

Z
.0

1

Physical Division, KEK
Physical Division, University of Pennsiivania, U.S.A.

Our measurement agrees with that by H.G. Bohlen,
who concluded that there are p-wave doublets at 0.42
and 0.8 MeV. When the spectrum by Young, who concluded that there is only one peak around 0.54 MeV,
is checked closely, there is a deviation from the fitting
on the left side of the peak. There may be still a possibility that their spectrum can be fitted with a doublet.
From the present measurement, we believe that it isconclusive that there are two p-wave states within 1
Me V from the threshold.

References
1) H. G. Bohlen et al. : Z. Phys., A344, 381 (1993).
2) B. M. Young et al.: Phys. Rev., C49 , 271 (1994).

79

RIKEN Accel. Prog. Rep. 29 (1996)

RHIC Spin Project
H. En'yo, K. Hatanaka, T. Ichihara, K. Imai, T. Katayama, A. Masaike, M. Okamura, N. Saito, Y. Sakemi,
T.-A. Shibata, H. Sato, Y. Watanabe, H. Wu, M. Yosoi, and M. Ishihara[pp interaction, structure function, spin, asymmetry, polarized beam.]
We promote the high energy spin physics project,
the RHIC spin project, utilizing the Relativistic Heavy
Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) in collaboration with BNL. One of the major goals of the project is to solve so-called proton spin
crisis. The project will open a new field combining thehigh-energy hadron physics and nuclear physics.
The project consists of two major parts, (1) acceleration of the polarized protons at RHIC and (2) construction of a muon-pair detector system. In this paper, the overview of the project is described. Following
two papers present the conceptual designs of those experimental apparatus and the spin control devices forpolarized beam acceleration.
The study of spin-dependent effects in deep inelastic scattering (DIS) has renewed the interest of thestructure of the proton. The result of European Muon
Collaboration experiment 1 ) was interpreted as a verysmall quark contribution to the proton spin. Possible
solutions of this problem are an unexpectedly polarized gluon or a sea-quark in the proton. In the process of the DIS , however, a gluon does not participate
at the leading order and the sea-quark contribution
cannot be separated from the quark contribution. In
the case of proton-proton collision, gluon contents canbe probed by high-PT prompt photon production andheavy quark production at the leading order; an antiquark can be tagged in W-production and Drell-Yan
process. Thus such an experiment will provide completely new information on the spin structure of the
proton.
The physics goals of the RHIC spin project are to
elucidate the spin structure of the proton, and to test
the standard model mainly via the parity violating process.
The RHIC complex for polarized proton beam acceleration is shown in Fig. 1. The polarized source, linac,
booster, and AGS exist. To maintain the proton polarization during its acceleration, the partial siberiansnake should be installed in AGS , and the full siberiansnakes should be installed in the RHIC main ring. The
full siberian snakes will be constructed by RIKEN.
The energy of the polarized proton beam will bevariable from 25 to 250 GeV, where the center-of-massenergies are 50 and 500 GeV, respectively. The luminosi ty is expected to reach to 2 x 1032 cm - 2 sec - 1.
At the highest energy, 500 GeV, production of weakbosons is copious. Thus it is suitable to study parity
violating effects. The variability of the beam energy

80

will allow us the study of Q2-dependence of the polarized structure functions, and the precision test of QCD
is possible.
There are two major experiments, PHENIX andSTAR. The STAR has the TPC-based detector system which covers the pseudo rapidity region, 1171 < 1.2.
The PHENIX, which we participate in, has two parts;
a central arm covering 1171 < 0.35 ; a muon-pair detector
system which covers 1.2 < 1171 < 2.4. The latter partis going to be constructed by RIKEN . The PHENIX isadvantageous in the capability of the particle identification and a powerful trigger system. Two experiments
are complimentary.
The construction of both of the accelerator devices
and experimental apparatus is scheduled to be completed until the end of March, 1999. The first collision
is expected on April 1, 1999.

RHIC

RHIC
\

Spin Rotators
Partial-- Siberian Snake

AGS:. i-- Polarimeter

Booster

200 MeVPolarimeter

Polarized H- Source
Fig. 1. Schematic representation of the RHIC accelerator
complex.

References
1) J. Ashman et al.: Phys. Lett., B264, 306 (1988).

RIKEN Accel. Prog. Rep. 29 (1996)

Muon Pair Detector System for RHIC Spin Project
H. En'yo, T. Ichihara, K. Imai, A. Masaike, N. Saito, Y. Sakemi, T.-A. Shibata,
Y. Watanabe, M. Yosoi, and M. Ishihara[pp interaction, structure function, spin, asymmetry, polarized beam.]
We are constructing a muon-pair detector system
for the RHIC Spin Project at Brookhaven National
Laboratory (BNL). It is a part of the PHENIX detector
system for Relativistic Heavy Ion Collider (RHI C). 1)
The detection of the muons with high momentum
resolution is the key to making the physics outputs
maximal. For example, we are going to detect muons
with a high transverse momentum from W± decays.
The momentum of such a muon provides a good measure of the momentum fraction, x, which is carried by
the initial quarks. Thus measurements of the muon
momentum with high resolution leads to good resolution of x.
Figure 1 shows the muon-pair detector system
schematically. Other components are not shown forclarity. The muon-pair detector system covers thepseudo rapidity region, 1.2 < IrJl < 2.4. It consistsof three parts: a muon magnet, muon tracking chambers, and a muon identifier.

plastic proportional tube. The cell size of the tube is
0.9 cm and eight separate cells are in one counter. The
counter is about 5 m long and 8.3 cm wide.
Each layer has two x and y planes with one staggeredto the other by a half cell to eliminate the geometricalinefficiency of a single plane.
The performance of the muon tracking system has
been studied utilizing G EANT 2 ) based simulation. Inclusive production of ZO in pp collision at yS = 500
Ge V has been simulated with PYTHIA 3) for this purpose. A typical event is displayed in Fig. 1. In this simulation the detector response has been fully simulated,
i.e. the signals in the tracking chambers have been simulated and momentum reconstruction has been performed.
Resulting dimuon mass resolution at ZO is shown in
Fig. 2. The spectrum has been fitted to Breit-Wigner
form smeared with Gaussian resolution. The mass resolution of 5.3 Ge V / c2 has been obtained. With therequirements of muon penetration up to the 6-th layerof the muon identifier, the ZO identification efficiency
is 96%.
!lx'/ndf
PI
P2
P3

c

=
o
\,/

46.32

I 38
20.15 ±
5.252 ±

90.68 ±

1.204
.2506
.2266

100

80

60

Fig. 1. Plan view of the muon-pair detector system. Overlayed is a typical event of ZO production in pp collision
at Vs = 500 GeV.

40

20

The muon magnet is to analyze the momentum of amuon with high resolution. The integrated magnetic
field is about 7500 and 2500 Gaussxm at e = 15° and
30°, respectively.
The tracking chamber system utilizes Cathode Strip
Readout Chamber technology and comprises three stations. Each station has the three gas volumes with thestructure of fine cathode plane, anode wire plane, andcoarse cathode plane. The spatial resolution of the finecathode plane is expected to be 100 microns.
The muon identifier consists of six layers of muon
detectors and five layers of hadron absorbers inserted
between the muon detectors. The muon detector is ao ~~==~~~~~~~==~~~
60m ~ % ~ m uo l~
dimuon mass (GeV/c )Fig. 2. Dimuon mass spectra in ZO production in pp collision at Vs = 500 GeV.
References
1) H. En'yo et al.: This report. p. 80.
2) GEANT: CERN Library Long Write-up, W5013.
3) H.-U. Bengtsson and T. Sjotrand: Comput. Phys. Commun., 46, 43 (1987); CERN-TH. 6488/92 and references
therein.
81

2. Atomic and Solid-State Physics

RIKEN Accel. Prog. Rep. 29 (1996)

Resonances in Photodetachment of H- (2p2, 3 pe)
J.-Z. Tang, C.-D. Lin,* B. Zhou,* and I. Shimamura
The cross sections for the photodetachment from thesecond bound state of a negative hydrogen ion, namely,
the H- (2p2 3 pe) state, at photon energies above theH (n = 2) threshold are calculated using a hyperspherical close-coupling method. 1 - 3 ) The energy of this statelies in the continuum H(18) + e, but this state is parity
forbidden to autoionize into H(ls) +e, and is therefore
a true bound state. The present study was carried out
for the following reasons.
First, to study the effect of the extremely weak binding of H- (2p2 3 pe), or of its diffuse wave function,on the photo detachment cross sections and their resonance structures. The binding energy with respect
to the H(n = 2) threshold is 0.01 eV, which is muchsmaller than the binding energy 0.75 eV of the groundstate H- (18 2 1 S). For reliable calculations of dipole
transition matrix elements at energies close to then = 2 threshold, the wave function of the extremely
diffuse initial state has to be calculated extremely accurately.
Second, to compare the photodetachment cross sections with those calculated by Jacobs et al. 4 ) using
three-state close-coupling wave functions for the finalcontinuum states, and with the recent results of Du
et al. ,S) who calculated the cross sections at low energies using a semi-empirical adiabatic hypersphericalapproximation. We found that the partial cross sections for leaving the hydrogen atom in the 2s and 2p
excited states are in good agreement with the closecoupling calculations of Jacobs et a1. 4 ) in a low-energy
region. At even lower energies than those covered by
Jacobs et al. , the photodetachment cross sections drop
rapidly toward the H(n = 2) threshold in agreementwith the results of Du et al. S)
Third, to locate and identify many shape (or potential) resonances and Feshbach resonances of H- associated with high-n thresholds. We also extended thecalculations to higher energies to analyze resonancesnear the H(n = 3) threshold. We found two series ofFeshbach resonances of 3 po symmetry, one series ofFeshbach resonances of 3 DO symmetry, and one shaperesonance each of these symmetries. The calculated
positions and widths of these resonances are listed
in Table 1. The existence of shape resonances justTable 1. Energies Er and widths r (in a.u.) of resonance states of H - lying close to the H(n = 3) threshold.
3.15[ -5] = 3.15 x 10- 5 .
Present-Err

H-epO)
1. Feshbach
2. Feshbach
3. Feshbach
4. Feshbach
5. Feshbach
6. Shape
H-CDO)
1. Feshbach
2. Shape

Complex coordinate 7)-Err

0.06791 1.65[- 3]0.05743 3.04[- 4]0.05640 4.15[-6]0.05592 6.42[-5]0.05563 1.33[-5]0.05478 8.92[-4]0.06791
0.057420.05638
0.05591
0.055620.05475

1.71[-3]
3.03[-4]4.00[ - 6]
5.65[-5]
1.20[-5]
8.5[-4]0.05578 3.15[-5]0.05555 2.46[-4]0.05577
0.05550

3.8[- 5]2.8[- 4]

above high-n excitation thresholds appears to be quite
common in H-. Using diabatic hyperspherical potential curves, we have assigned a set of commonlyused correlation quantum numbers 6 ) to these Feshbach and shape resonances. The calculated resonancepositions and widths are in good agreement with thevariational results obtained by Ho and Bhatia7 ) using
the complex-coordinate rotation method as shown in
the table. The details of the work have been reported
elsewhere. 8)
References
1) J.-Z. Tang, S. Watanabe, and M. Matsuzawa: Phys.
Rev. , A46 , 2437 (1992).
2) J .-Z . Tang and I. Shimamura: ibid., A50, 1321 (1994).
3) J.-Z. Tang and I. Shimamura: RIKEN Accel. Prog.
Rep., 28, 62 ; 63 (1995) .
4) V . L. Jacobs, A. K. Bhatia, and A. Temkin: Astrophys.
J. , 202 , 1278 (1980).
5) N.-Y. Du, A. F . Starace, and M.-Q. Bao: Phys. Rev.,
A50 , 4365 (1994).
6) C. D. Lin: ibid. , A29 , 1019 (1984); Adv. At. Mol. Phys.,
22 , 77 (1986).
7) Y. K. Ho and A. K. Bhatia: Phys. Rev., A48, 3720
(1993); Y. K. Ho (private communication) .
8) J.-Z. Tang, C. D. Lin, B. Zhou, and I. Shimamura:Phys. Rev. , A5! , 4694 (1995).

Kansas State University, U.S.A .

83

RIKEN Accel. Prog. Rep. 29 (1996)

Angular Distributions of Photoelectrons from Helium
J .-Z. Tang and 1. Shimamura

Photoionization of helium, a seemingly simple
two-electron problem, has been attaining more andmore theoretical and experimental interest recently.
Experimentally, the recent high-resolution measurements have revealed rich structures in the spectra of total (TCS) and partial (PCS) photoionization cross sections and the angular distributions ofphotoelectrons. 1 ,2) Theoretically, powerful computational methods have been developed recently and they
produce results that agree very well with each otherand with experiments on the TCS and the resonanceparameters for doubly excited states converging to lown thresholds. However, there are significant discrepancies among theoretical results 3 ) on the photoelectron
angular distributions or the differential cross sections(DCS), and hence on the asymmetry parameter often
denoted by {3. The TCS and PCS depend only on
the absolute values of the dipole transition amplitudes,
while the DCS depends also on the relative phases ofthese amplitudes. This implies that the DCS and (3contain more physical information than the TCS andPCS and are more sensitive than the latter to the details of the effects considered in a particular calculation.
In this work, we apply the hyperspherical closecoupling (HSCC) method 4,S) to study the DCS forphotoionization of He in the energy range between the
n = 2 and 4 thresholds. This method has proved to bequite powerful in reproducing the experimental TCS
and PCS measured with high resolution; see, e.g., Ref.
6. Therefore it is expected to lead also to reliable results on the angular distributions and asymmetry parameters. The wave function for the total two-electron
system is expanded in terms of hyperspherical basis
functions ,4,S) set up ab initio. This expansion is foundto converge rapidly. At some point of the hyperradius,
the wave function is connected smoothly to an outerregion wave function in independent-electron coordinates , as explained before. 4,S)
We have found in the DCS and in {3 not only theresonances clearly seen in the TCS but also those narrow resonances that are hardly recognized in the TCS.
Some differences between the present theory and experiments have been attributed to the estimation of
the experimental background and to the particularly
strong inf:l.uence of the finite experimental resolution on(3. After making corrections for them, the calculated

84

spectra Gaussian convoluted with an experimental resolution agree quite well with the experimental data in
Ref. 1, unlike previous t heoretical results. 3 ) The Fig.
1 compares the present results for the DCS with thedata from Ref. 1 at 0 0 and 90 0 between the n = 3 and4 thresholds. Part of this work has been published inRef. 2.
...-..

'(/)

.c 9
6
(/)

c:

8

.2 7
t5
Q)
(/)
(/)
(/)

0

'-

u

CO
:.;:::

c:

Q)

'-

~
0

74
Photon energy (e V)

Fig. 1. The differential cross sections at ( a) 0° and (b) 90°
for photoionization of He: hv + He --t e + He+ (n = 2).
Solid curve: present result convoluted with a resolution of 60 meV. Circles: experimental results of Ref. 1
corrected in this work for a linear background.

Further results of the present calculations agree wellwith recent high-resolution measurements, as is discussed in detail elsewhere in a joint experiment altheoretical paper. 2 )References
1) M. Zubek et al.: J. Phys. B, 24, L337 (1991).
2) A . Menzel et al: Phys. Rev. Lett., 75 , 1479 (1995).
3) I. Sanchez and F. Martin: Phys. Rev., A48, 1243
(1993) , and the references cited therein.
4) J .-Z. Tang, S . \yatanabe, and M. Matsuzawa: Phys.
Rev. , A46 , 2437 (1992).
5) J.-Z. Tang and I. Shimamura: RIKEN Accel. Prog.
Rep. , 28, 62; 63 (1995).
6) J.-Z. Tang and I. Shimamura: Phys. Rev., A50, 1321
(1994).

RIKEN Accel. Prog. Rep. 29 (1996)

Double Photoionization of Helium at Low Photon Energies
J.-Z. Tang and 1. Shimamura
Theoretical calculations of double photo ionization(DPI) are quite difficult in general, partly because
one has to deal with double continua involving thetwo emitted electrons, and partly because the crosssection is as small as several percent of the singlephotoionization (SPI) cross section at most. The
single-photon DPI never occurs if the electron-electron
correlations are ignored, and this correlation is strong
especially in the low-energy region, i.e., for photon energies from the dou ble-ionization threshold to several
hundred eV. In the present work, we carried out accurate calculations of DPI of a prototype atom, He, inthe low-energy region by extending the hypersphericalclose-coupling (HSCC) method.!) The details of thework have been reported elsewhere. 2 )Among the existing ab initio computational
schemes for DPI, the many-body perturbation theory(MBPT)3) and the eigenchannel R-matrix method 4 )have been most successful. The first method, MBPT,
treats the electron-electron interaction in a perturbative way and is expected to be a better approximation
at high energies 3) than at low energies. The R-matrix
method of Ref. 4 is a close-coupling approach using
pseudostates to represent the continuum. The DPI
cross sections calculated by these methods depended
on the adopted form of the dipole operators, which isan indication of the inaccuracy of the calculations.
Compared with the MBPT method, the present one
is non-perturbative and the electr~n-electron correlation effect is more accurately included. The present
method is a close-coupling-type approach just as the
R-matrix method and uses, in the outer region (where
one of the electrons lies far from the rest of the systern), asymptotic solutions for an electron interactingwith He+ in discretized pseudostates that simulate thecontinuum states of He+ and that are similar to thepseudostates used in Ref. 4. In the inner region (where
all the three particles in the system lie close together),however, the wave function of the total system is expanded in terms of hyperspherical basis functions!) in
the present method, and close-coupling equations in
the hyperradius are numerically solved. This results infaster convergence than the expansion in terms of basis functions in independent-electron coordinates, likethose used in Refs. 3 and 4.
The calculated DPI cross sections are compared inFig. 1 with those obtained by the MBPT and the Rmatrix method. The present results were obtained byusing 175 basis functions and by matching the inner-....-....

~8
c

0

+-'

U
Q)
CI)

(j')
(j')

4

0

~

u

0..

0

0 80

160
240
Photon energy (eV)Fig. 1. Double photoionization cross sections for He. Solidand short-broken curves: A(acceleration) and L(length)
forms, present method. Dot-dash and long-broken
curves: A and V(velocity) forms, R-matrix method. 4 )+ and 0: A and L forms, MBPT. 3 )region and outer-region wave functions at a hyperradius of 30 a. u. The convergence of the SPI cross section within 3 significant digits and of the DPI crosssection within several percent has been confirmed. An
outstanding feature of the present results is that thecross sections obtained in the length and acceleration
forms agree very well with each other. This fact , together with the good convergence of each cross section,
guarantees the accuracy of the present results. The
calculated ratio of the cross sections for double to single photoionization is smaller than most experimental
data, but is in excellent agreement with a very recent
accurate measurement. 5 ) We note finally that the DPI
cross sections, obtained in Ref. 6 by a new method
based on an integral form of the amplitude function
for DPI, are close to the present results.
References
1) J.-Z. Tang, S. Watanabe, and M. Matsuzawa: Phys.
Rev., A46, 2437 (1992).
2) J.-Z. Tang and 1. Shimamura: ibid., A52, 2437 (1995).
3) K. Hino et al.: ibid., A48 , 1271 (1993).
4) K. W. Meyer and C. H. Greene: ibid., A50 , R3573(1994).
5) R. Dorner et al.: preprint.
6) M. Pont and R. Shakeshaft: 1. Phys. , B28, L571 (1995).

85

RIKEN Accel. Prog. Rep. 29 (1996)

Scattering Angle Dependence of Electron Impact on O 2 and CO
M. Kimura, M. A. Dillon,* R. J. Buenker,** G. Hirsch,** Y. Li,** and 1. Chantranupong**
Intensity distributions of electronic transitions in O 2
and CO within a vibrational progression resulting fromelectron impact excitation are studied theoreticallyand experimentally. The multireference single- anddouble- excitation configuration-interaction (MRD-CI)
method is used to elucidate details of selected electronic transitions. Figure 1 illustrates adiabatic potential curves for CO obtained by the MRD-CI. In
particular, the adiabatic MRD-CI approach can account for the variation of the Franck-Condon envelop
with scattering angle that has been reported for the
BI 'L.+ ~ XI'L.+ transition in CO and also was recently observed in the B 3 'L.- ~ X 3 'L.- transition ofO 2 , This behavior contrasts with the relative stabil-

ity of the intensity distribution observed within the
CO: A I IT ~ XI'L.+ vibrational progression as exemplified in Fig. 2. In the former case, the excitedstate undergoes changes in its charactor with internuclear separation because of the presence of an avoided
crossing. Since a transition from the zeroth vibrational
level in the ground electronic state to an individual vibrational level in the excited electronic state tends toselect a particular internuclear distance (R-centroid),each vibrational band may behave as a transition toa separate electronic level. This happens because theexcited state wavefunction undergoes a compositionalchange with internuclear separation between the adiabatic partners of the avoided crossing. The details
have been published elsewhere. I)

20

Ground States ......t------------._..
a
x 10

CO

1.5°

CO

/

>' 15
~

10

9.6

10

10.4

10.8

10.6

10.8

11

11.4 7.S

8

8.S

9

9.S

10

Energy Loss (e V)5Fig. 2. Electron energy loss spectra for B,3L, ~ X 3 L,
transition in O 2 and BIL, ~ X1E transition in CO.

2

2.2

2.4

2.6

2.8

3

R (au)
Fig. 1. Adiabatic potential curves for the CO molecule.

Argonne National Laboratory, Argonne, U.S.A.
Theoretisch Chemie, Bergische Universitat-Gesamthochschule Wuppertal, Germany

86

References
1) M. A. Dillon, M. Kimura, R. J. Buenker, G. Hirsch, Y.
Li , and L. Chantranupong: J. Chern. Phys., 102, 1561
(1995).

RIKEN Accel. Prog. Rep. 29 (1996)

Electron Energy Distribution Functions and Thermalization Timein Methane and in Argone-Methane Mixture
M. Kimura, 1. Krajcar-Bronic,* and 1. Shimamura
Electron energy distribution and thermalization inmethane and argone-methane mixtures are studied
by using the Boltzmann equation. Suppose that themedium consists of two species at number densities N A
and N B atoms or molecules with mass MA and M B . If
no external field is applied and spatial spherical symmetry of the initial electron distribution is assumed,then electron distribution function f( v, t) of speed v
at time t satisfies the Boltzmann equation,
8f(v, t)8t

sections for CH 4 are included in the calculation. The
details can be found elsewhere. I)- - N. mom. tr.
----- CH•• mom. tr.

. .. . ... . CH•• v(Z-4)

10

--..-

CH•• v(l·)

..r

eu

...
= Jel + Jinel,(1)

where Jel and J inel are the elastic and inelastic collision operators. The calculated condition for the thermalization of electrons is: the initial electron energy
is 1 eV in CH 4 and Ar gases at T = 300 K and p= 1 atm. The presence of low-lying vibrational excited states in methane significantly changes electronenergy distribution functions and relaxation time. We
found that (1) the mean electron energy just below the
first vibrational excited state is reached faster by 1000
times when the vibrational states are taken into account, and (2) electron energy distribution functions
have distinct peaks at energy intervals equal to the vibrational threshold energies. Both these effects are due
to a large vibrational stopping cross section. The thermalization time in mixtures of argone-methane without vibrational states smoothly changes as the mixture composition varies , and no significant difference inthe electron energy distribution function is observed.
When the vibrational excited states are taken into account, the thermalization is almost completely definedby CH 4, even at very low fractional concentrations ofCH4. The sensitivity of the electron energy distribution functions on the momentum transfer cross sections
used in calculation on the thermalization is tested and
it is found that in the present range of deviation in momentum transfer cross sections, the effect is not significant. Figure 1 shows electron collision cross sections
for both momentum transfer and vibrational excitations for CH 4 and momentum transfer cross section
for Ar used in the calculation. Figure 2 illustrates electron energy distribution functions (time-evolution) in
Ar-CH4 mixtures when only momentum transfer cross

~
b

0.1

0.01
0.01

10

0.1

E (eV)

Fig. 1. Electron collision cross sections for both momentum transfer and vibrational excitations for CH 4 andmomentum transfer cross sections for Ar.

T= 300K
p=latm

10'
10"
10~

10-3

- 1 x l 0·'.
.... 1x1 0" ,10"···· ·· · 4. ,0.. ,-_._ "'0.

7,

1<T$

..· ····· 2xl0· 7 S....-_. 4.,0.7,

10"-1.,0",-- 2.,0",-4.,0",

10"
10"
10'·

0 .0

02

0.6

0.4

1.0

E (eV)

Fig. 2. Electron energy distribution functions (time evolution) in Ar-CH 4 mixtures, when only momentum transfer cross sections for CH4 are included in the calculation.

References
1) I. Kraj car-Bronic, M. Kimura, and I. Shimamura: to besubmitted in J. Chern. Phys.

Rudjer Boskovic Institute, Croatia

87

RIKEN Accel. Prog. Rep. 29 (1996)

Correlation between the Carbon K-Shell X-Ray
Emission Rates in Molecules
M. Kimura
A clear correlation is shown between carbon K-shell
X-ray emission rates from molecules that contain carbon atoms and their 7r bond orders. This correlation
is based on the present calculation for C 2 H 2 , C 2 H 4
and C 2 H 6 and previous calculations of Larkinsl) for
CO, CO 2 , HCN and CH 3 0H. Because the 7r bond order has an inverse linear relationship with the bondlength, the C K-shell X-ray emission rate correlateswith the bond length as well. Some rationale for thefindings based on electronegativity and charge distribution is given. The correlation manifests itself in achemical effect on the C K-shell X-ray emission rate.
Figure 1 displays the present C X-ray emission rates
and Fig. 2 shows the Auger transition rates as a function of the valence electron density in carbon together
with the data obtained by Larkins.l) As Fig. 1 shows

11

=

cu 10
'0

=

CH

9 •I 6

q,j

co...
cQ

01 3 OH

•

...

CH

8

CO
CIHz • z
HCN

'Vi
(I'J

•

·s 7
q,j

;.-.

...cu
><

•

co

•

6

5
0

0.5

1

1.5

2

2.5

3

3.4

=
<0

3
2.6

'-'

2.2

q,j

•

C

•

co...
... 1.8
q,j
01)

<=

0I 3 0H

co

,.,

=
....

•

•

HCN

Auger rate
1.4
I

3.8

4

4.2

4.4

4.6

4.8

Valence electron density

Fig. 2. Auger transition rate as a function of valence
electron density. All data are from Larkins. 1 )forC 2 H 6 , in which no 7r orbital exists, the 7r bond order is very small. All valence electrons in this molecule
are in (j orbitals that are well-localized near inner shellorbitals resulting in a large X-ray emission rate. As
seen in Fig. 2, the Auger transition rate appears toincrease linearly as the electron density increases. For
the Auger transition, the electron correlation operator is the source of the dynamics and hence, the total
coupling strength depends on the electron density in amolecule. As the electron density increases, the overall coupling strength per molecule increases, leading toa larger Auger rate. The details have been publishedelsewhere. 2)

1t-Bond order

ReferencesFig.
1.
X-ray emission rates for a variety of carbon-containing molecules as a function of 7r bond order.
Present work: solid square; Larkins: solid circle.

881) F. P. Larkins: J. Electron Spectrosc. R elat. Phenom.,
51, 115 (1990).
2) M. Kimura: Chem. Phys. Lett. , 200, 524 (1992).

RIKEN Accel. Prog. Rep. 29 (1996)

Charge Transfer Effect on Double Electron Excitation of Heliumby Proton Impact
N. Fukushima,* T. Morishita,* K. Hino, S. Watanabe, and M. Matsuzawa
We report an autoionizing electron emission crosssection from a doubly-excited helium in the N = 2
manifold produced by proton impact. The electron
emission process by proton and anti-proton impact
in the MeV-energy region has been intensively studied these few years to analyse sensitive dependenceof resonance profiles on a sign of projectile charge
due to interference among several partial waves of theejected electron. 1 ,2) Theories have well reproduced experimental findings regarding both backgrounds anddoubly-excited resonances. When the incident energy
decreases down to a hundred ke V -region, special attention has to be paid to the following two important
effects on the excitation process; that is, the chargetransfer and the post-collision interaction contributions to an electron emission cross section. In thisreport, only the first issue will be taken into consideration. This takes effect only to the case of proton
impact.
Ab initio close-coupling method is employed in theimpact parameter representation. Basically, we adopt
a one-center atomic orbital expansion in terms of helium wave functions obtained by the hypersphericalclose-coupling method. 3 ) The hyperspherical method
is known to be one of the excellent ways to take into
account a strong electron correlation effect in a twoelectron atom. Instead, as a price to be paid, the adoption of it causes a numerical difficulty in calculating acoupling matrix element between a projectile-centeredatomic wave function and a (target-centered) hyperspherical wave function. This difficulty hampers astraightforward application of an additional projectilecentered atomic orbital expansion to the present closecoupling scheme to evaluate a charge transfer channel.
The manipulation adopted here to remedy this difficulty is the following. First, relevant coupling matrix
elements for a charge transfer channel are evaluatedusing a (target-centered) Hartree-Fock wave function___ j _n stead of a hyperspherical one, since it is thought thatthe electron correlation effect on a one-electron chargetransfer would be small. Such one-electron matrix elements are relatively tractable. Next, the scatteringmatrix elements for a charge transfer are calculatedusing these coupling matrix elements by the method
pertinent to the incident-energy region concerned here,
for instance, by the first-Born approximation or the

distorted-wave Born approximation if necessary. Finally, these predetermined matrix elements are introduced into the two-electron close-coupling equation as
inhomogeneous terms expressing a coupling between a
direct channel and a transfer channel.
Figure 1 shows our preliminary result for the electron emission spectrum ascribable to the (28)2 1
state induced by the 150 keV proton bombardment.
This calculation includes only a Is-Is charge transfer channel obtained by the first-Born approximation.
Here, for simplicity, a screened hydro genic wave function has been used for evaluating a transfer scattering matrix element in place of a Hartree-Fock one.
There is little difference between spectral profiles withand without considering the charge transfer effect.
Extended calculations including more charge transfer
channels are in progress.

se

>Q)

--E

N

o

u

C)l

o
.....
Cf)

()

Cl

Cf)

33.1

33.2

33.3

33.4

Ejected Electoron Energy (eV)Fig. 1. The electron emission cross section (SDCS, single
differential cross sections in energy) from the (2s) 2 1 Se
doubly excited state of helium by 150 ke V proton impact. The solid and the dashed lines stand for calclulations with and without considering a charge transfer
channel, respectively.

References
1) T. Morishita et al.: J. Phys. B: At. Mol. Opt. Phys., 27,
L287 (1994).
2) T. Morishita et al.: to be submitted in Phys. Rev. A,
Other references therein.
3) J. Z. Tang et al.: Phys. Rev., A46, 2437 (1992).

Department of Applied Physics and Chemistry, University
of Electro-Communications

89

RIKEN Accel. Prog. Rep. 29 (1996)

Electron Capture in Slow 0+(48,2 D, 2 P)-He Collisions:
Effects of Metastable Ions
M. Kimura, J. P. Gu,* G. Hirsch,* R. J. Buenker,* and A. Dalgarno**
Recently reports appeared on two experimental attempts by Kusakabe et al.l) and Wolfrum et al. 2) tostudy the single-electron capture in collisions of 0+ions with He atoms in the ke V regime. The results
have led to two conflicting conclusions: Kusakabe etal. predicted larger cross sections when metastable ionswere present, whereas Wolfrum et al. found no contribution from metastable ions. The processes they dealt
with are the following with respect to asymptotic energy defects and the corresponding adiabatic potential
curves are shown in Fig. 1:0+(48) + He ----+Oe P) + He+ + 10.96 eV

10. 140+(4S/D,lP) + He Electron Capture

Metastable O+(lD+lp)
N~

E

~

"

10. 1 '"

90% 0+(4S)+10% O+(lD/P).......

0::

.~

a!I>

~

'"'"0

U

CD •

10. 11•••• • Ground 0+(4S)
to· It0.1

10
E (keV)0+(2 D) + He ----+ 0(3 P) + He+ + 7.64 eV
O+e P) + He ----+Oe P) + He+ + 5.94 eV.

·0.75

HeO' Adiabatic potentials-0.9125:;~ -1.075'-l

O·(IPl + Ht
0.(10) + Ht

-1.237

-1.4

1.5

2.8

4.1

5.4

6.7

R (a.u.)Fig. 1. Adiabatic potentials of the HeO+ system. Theenergy is given relative to -76.0 a. u.

-

The present cross sections for electron capture by
the ground 0+(48) state and metastable 0+(2 D, 2 P)
states are presented in Fig. 2.
The cross sections clearly show that the electron capture by themetastable ions is more probable by an order of magnitude than that by the ground state. Kusakabe et al.

Theoretisch Chemie, Bergische Universitat-Gesamthochschule Wuppertal, Germany
ITAMP, Harvard-Smithsonian Center for Astrophysics,
U.S.A .

90

Fig. 2. Electron capture cross section above 100 eV.
Present work: . , 0 +(4 S); ., 0 + (2 D ,2P). Experiment:
0, 0 +(4 S); 0 , capture by mixed ground and metastable0+ ions, Kusakabe 1 ) et al. and Wolfrum et a1. 2 )used a technique of electron impact ionization of the
CO 2 molecule to generate 0 + ions, but the fraction ofmetastable-state ions is not known. Wolfrum et al. on
the other hand, used a similar technique on the H 2 0molecule and reported that in their 130-eV electron impact, the ions produced were 47%0+(48), 40%0+e D)
and 13%0+(2 P) . In contrast , for 30-eV electron impact , only the ground state of 0+ ions was produced(100%). As Hughes and Tiernan reported,3) the appearance potentials for 0+ (2 D) and 0+ (2 P) ions are
26.5 and 28.3 eV, respectively. Hence, a mixture of asmall fraction of metastable 0+ ions could well be expected when 30 e V electrons are used. Therefore, we
suspect that metastable 0+ (2 D, 2 P) ions were actually present in all experiments in the work of Wolfrum
et al. The details have been published elsewhere. 4)
References
1) T. Kusakabe et al.: l. Phys. Soc. lpn., 59, 1987 (1990).
2) E. Wolfrum et al.: Phys. Rev., A45, R4218 (1992).
3) M. Hughes and 'T. O. Tiernan: l. Chern. Phys., 55,
3419 (1971).
4) M. Kimura et al.: Phys. Rev., A49, 3131 (1994).

RIKEN Accel. Prog. Rep. 29 (1996)

Electron Loss from H- under Energetic, Highly Ionized Ion Impact
H. Tawara, T. Tonuma, H. Kumagai, and T. Matsuo
Electron loss processes from negative hydrogen ions
under collisions of ions,;... 4•c.§

are important in various fields such as the development of powerful ion sources and plasma apparatus.
In particular, much attention has recently been paid totheir applications to fusion plasma research relevant toneutral plasma heating. Though their importance has
been noted in many years, only limited experimental
investigations have been reported until now because oftechnical difficulties. 1- 6 )In the present work, the electron loss processes fromH - ions under energetic (MeV I nucleon) highly ionized heavy ion impact is planned to be investigated.
2.5 ke V H- ion beams, extracted from an off-centered
duoplasmatron ion source with ferrite permanent magnets and purified through two electrostatic deflectors,
are crossed at 45 degrees with 1- 2 MeV Inucleon Aq+(q = 6- 30) ions provided from RIKEN linear accelerator, as shown in Fig. 1. Typical beam-overlapping
shapes , which are the most important in ion-ion collision experiments, are shown in Fig. 2.
In ion-ion collision experiments, as the target ion
densities are generally very low compared with those

Beam

3

c

.$2

o

2

4

6

8

10

12

Position (mm)Fig. 2. Overlapping shapes of 1.5 MeV/nucleon Ar6 +beam and 2.5 keV H- ions.

of residual gas atoms, both of the colliding ion beams
have to be chopped in order to improve the signal-tonoise (SIN) ratios. In the present experiment , we have
tried to use the unique time-structures of the accelerated ion beams from the LINAC , which are known to
be short-bunched at the accelerating frequency. We
have found that careful RF-tuning is necessary in order to minimize the tails of the bunched beams which
are expected to significantly influence SIN ratios, justas that in the beam-chopping technique. This is expected to increase S IN ratios by a factor of about 20
at the bunched beam width of 1.5 ns at 33 MHz. It
has been found experimentally that the tails of thetime-structures of ion beams can be also reduced significantly through proper adjustment of the beam collimating slits, though some fraction of ion beams may
be lost.
In the present collision energies, the electron loss
from H- ions is expected to be dominated by the pureionization under the influence of the strong Coulomb
field of projectile ions.
N ow we are trying to measure the cross sections
mentioned above and also to look into the detailed
mechanisms in electron loss processes involving Hions under highly ionized MeV Inucleon ion impact.
Referencesoo 50 100 mm~

Fig. 1. Schematic experimental apparatus.

1) E. Salzborn: J. de Phys. , Suppl., 50, Cl-207 (1989) .
2) K. Dolder and B . Peart: Rep. Prog. Phys. , 48, 1283
(1985).
3) F. Melchert et al.: BNL Symp. , p. 789 (1992).
4) F. Melchert et al.: Phys. Rev. Lett. , 74, 888 (1995).
5) L. P. Presnyakov, H. Tawara, and D. B. Uskov: Nucl.
Instrum. Methods Phys. Res., B98, 332 (1995).
6) G. D . Alton , R. A. Sparrow, and R. E. Olson: Phys.
R ev. , A45, 5957 (1992).

91

RIKEN Accel. Prog. Rep. 29 (1996)

Close-Coupling Calculations of Electron Capture from
Circular Rydberg States
M. F. V. Lundsgaad,* N. Toshima, and C. D. Lin*In a recent letterl) Hansen et al. reported electron
capture cross sections from circular Rydberg states asa function of the angle, r..p, between the ion velocity andthe angular momentum of the circular orbital. They
studied the collision of 2.5 keY 23Na+ on the Rydberg
state ofLi with n=25 , l=n-1 and m=+l, where m isdefined relative to a weak, external magnetic field. It
was found that the electron capture cross section depends strongly on the angle <p, with the maximum occurring at <p = 90° and decreases rapidly with decreasing <po Attempts have been made by Hansen, with limited success, to interpret this r..p-dependence in terms ofhigher order perturbation theories and in terms of results obtained for lower n states (n = 10) calculatedusing the classical trajectory Monte Carlo (CTMC)
method. 2) In this report, we show that the observed<p-dependence is consistent with the known propensity
rule for electron capture from low-lying excited states.
This propensity rule has been proved based on the results from elaborate close-coupling calculations3) andfrom experiments for collisions of protons on orientedNa(3p) states. 4 ) We carry out close-coupling calculations to determine the r..p dependence for electron capture from a circular H( 4f) state by protons at the same
scaled collision velocity (the ratio of the projectile velocity to the initial orbital velocity of the electron) ,and show that the calculated r..p-dependence is nearly
identical to the measured result for the n = 25 circularstate by Hansen et al.
To specify the collision more precisely, we first define the "natural frame" of reference. In this frame thecollision plane is the x' y' halfplane where y' is positive and +x' is the direction of the incident beam.
The quantization axis (+z' direction) is perpendicular
to the scattering plane such that x' y' z' forms a righthanded coordinate system. A circular Rydberg stateli)B = In, l = n-1, mi = l)B, where mi is given withrespect to the zB-axis, can be obtained from rotating
the circular state In, l = n - 1, mi = l)' defined withrespect to the natural frame x'y' z' by two successive
rotations,li)B = LLD~~i(O,-<p,O)D~q(71+7l'/2 ' 7l'/2 ' 7l')lnlm) .
q

(1)

m

In the equation above, V is the rotation matrix andT} is the rotation angle of the scattering plane x' y' withrespect to the space fixed xz plane (z=x'). The amplitude a7i(r..p,b,T}) for the transition li)B ~ If) depends
on the angles r..p, T}, and the impact parameter b. Thisamplitude can be expressed as a coherent sum of amplitudes defined with respect to the natural frame,
Department of Physics, Kansas State University, U.S.A.

92

ai(r..p,b,T}) = L L iq (-l)mmq

x exp(iqT})d~~C7r/2)d~~q(r..p)a;m(b), (2)where d is the reduced rotation matrix.
We obtain the cross section by integrating the transition probabilities over the impact parameter planeand summing over all the final states,

CJcap(r..p) = L(d~~ q(r..p))2qx

L L d~~(7r/2)d~~q(7r/2)P~m"m

where
P'mm' =

(3)m'

L27l' Jajm(b)aj:n, (b)b db.
00

f

(4)

0

The results are shown in Fig. 1, together with thedata of Hansen. l ) Interestingly, the agreement between
the ·calculations for the circular state for n = 4 and theexperimental results for the circular state for n = 25
is amazingly good. This suggests that the observed
r..p-dependence is insensitive to the principal quantum
number of the initial Rydberg state. Further details of
the calculations are given elsewhere. S )

'2
:::>

1g.

3D

t>U

c

.S!

20

~

Vl
Vl

e

u

o o~--~--~--~--~--~~
15
JO
45
60
75
Angle of orientation <p (degrees)Fig. 1. Comparison between the experimental cross sections (dots) for electron capture from a circular Rydberg state (n=25, £=24, m=24) and the theoreticalcross sections (solid line) for capture from a (n=4, £= 3,m=3) circular state. The collision velocity is 1.66 timesof the average electron velocity in both cases.

References
1) S. B. Hansen, T. Ehrenreich, E. Horsdal-Pedersen, K .
B. MacAdam, and L. J. Dube: Phys. Rev. Lett. , 11,1522 (1993).
2) G. A. Kohring, A. E. Wetmore, and R. E. Olson: Phys.
Rev. , A28 , 2526 (1983).
3) N. Toshima and C. D. Lin: ibid., A46, 2564 (1992).
4) A. Dubois, S. E . Nielsen, and J. P. Hansen: 1. Phys.,
B26, 705 (1993).
5) M . F. V. Lundsgaad, N. Toshima, and C. D. Lin: Phys.
Rev., A51 , 1347 (1995).

RIKEN Accel. Prog. Rep. 29 (1996)

Single- and Double-Charge-Exchange Cross Sections
for Ar q + + H2 Collisions
M. Kimura, 1. Shimamura, and N. Shimakura
The cross sections for single-electron capture, including transfer ionization, and for double-electron
capture, have been measured recently for Arq+ + H2
collisions for q = 6, 7,8,9, and 11 with projectile energies from q eV to q ke V. 1) For understanding thephysics underlying these processes, theoretical calculations have been made for Ar6 + and Ar 8 + impact using
a molecular-state expansion method in the energy region from 240 e V to 80 ke V, 1) and good agreement has
been found with the experimental results. Here, thetheoretical part of the work is briefly described. The
details of the whole work involving both experimentand theory have been published elsewhere. 1 )A semiclassical molecular-state expansion method,which is believed to be valid for collision energies above
a few 10eVlu, has been used. Molecular states of thesystem (ArH 2)q+ were obtained by the configurationinteraction (CI) method with Slater-type orbitals. In
this CI calculation, the two H2 electrons were treatedexplicitly, while the effect of the more tightly boundelectrons of Ar ions was represented by Gaussian-type
pseudopotentials. These pseudopotentials were determined so as to reproduce the energy levels of Ar(q- l)+.
The H2 molecules were approximated by atoms having an average first- and second-ionization potentials
of 15.8- 16.1 and 31.7 eV, respectively, average meaningthat over the vibrational wave function squared.
Several sets of coupled-channel calculations using

straight-line trajectories for the heavy-particle motion,
including different molecular states were carried out toassess the convergence and to identify dominant collision mechanisms or reaction paths. A typical set included (1) the initial channel Ar q + +H2 ' (2) representative single-electron-transfer channels Ar( q -1 ) + (n =3: 4) + H;, and (3) some dou ble-electron-transfer channels Ar(q-2)+(n = 3, n' = 3,4, 5)+2H+.
For Ar 6 + impact, the molecular-state expansion calculation produced cross sections that are about 50%
below the experimental values for both single and double capture. For Ar 8 + impact, the calculation is in better agreement with experiment for both single and double capture. Because of the extra two electrons in Ar 6 +in comparison with Ar 8 + , the quality of molecularstate calculations was somewhat lower for Ar 6 + impact, giving less satisfactory agreement with the experiment. The general trends of the cross sections agree
quite well with each other between the experiment andthe theory.
See Ref. 1 for further details of comparison between
theory and experiment and discussion of the dynamics
of the measured and calculated processes.
References
1) S. Kravis, H. Saitoh, K. Okuno, K. Soejima, M. Kimura,
I. Shimamura, Y. Awaya, Y. Kaneko , M. Oura, and N.
Shimakura: Phys. Rev. , A52 , 1206 (1995).

93

RIKEN Accel. Prog. Rep. 29 (1996)

Electron Capture in H+ + CH 4 Collisions
M. Kimura, Y. Li,* G. Hirsch,* and R. J. Buenker*
Electron capture and direct elastic scattering in collisions of H+ ions with CH 4 molecules are studied byusing a molecular representation within fully quantummechanical approaches below 1. 5 ke V. Calculations arecarried out at two different molecular configurations:(1) C3v symmetry, in which H+ approaches along thedirection of a C-H in CH 4 , and (2) C 2v symmetry, inwhich H+ approaches along a bisector of an H-C-H
bond angle. Figure 1 shows adiabatic potential curves
for C 2v symmetry. We find that the electron capturein the C 2v symmetry configuration takes place preferentially over that in the C 3v symmetry configuration
at scattering angles below 15° at 1.5 keY, and that thesituation reverses at larger scattering angles. Hence,
interferences arising from these molecular configurations on differential cross sections for the electron capture and elastc scattering processes are present but
weak, except for angles near the crossing. Accord-

ingly, the total cross section for the C 2v symmetry islarger by more than an order of magnitude, because inthis symmetry H+ can penetrate deep inside the electron distribution of a CH 4 molecule, causing a strong
interaction. The present differential cross section from0.01 to 1.0 degrees at 1.5 keY is shown in Fig. 2 alongwith experimental data. 1 ) In addition, the angular dependence in the differential cross section is quie different for the two molecular configurations at all energies
studied. The details have been published elsewhere. 2)........
10'-----..

...
"s
~
c::'0
<II

10·

:g

101

-

- - CJ.
- " ' C1.

--C1.-CJ •'.

H+ +CH. Electron capture
E = I.S keY

Gao et a I.

10·~==~~~=L~~L---~~~~~~LJ·40.080.01

0.1

e (deg):i~ ·40.25~

Fig. 2. Differential cross section from 0.01 ° to 1.0° at
1.5 ke V. The solid line shows the averaged result, thedashed-dotted line the result for C3 v , and dashed threedot line the result for C 2 v . The. symbols represent theexperimental data of Gao et al. l )·40.42.40.6 '--'-->=:........L.--'--L-.............I..-.L-'--"--'---'--'--L-.............L.-.L-'--'--'
o
2
4
10
6
8
R (a. D.)

Fig. 1. Adiabatic potential energies for H+ + CH4 C 2v
symmetry.

Theoretisch Chemie, Bergische Universitat-Gesamthochschule Wuppertal, Germany

94

References
1) R. S. Gao et al.: Phys. Rev., A41, 5929 (1990).
2) M. Kimura, Y. Li , G. Hirsch, and R. J. Buenker: Phys.
Rev. , A52, 1196 (1995).

RIKEN Accel. Prog. Rep. 29 (1996)

Double and Single Ionization of Helium and Hydrogen Molecules
by Slow Protons and Antiprotons
M. Kimura, I. Shimamura, and M. Inokuti*
The first series of atomic collision experiments using an antiproton beam of energy above 0.5 MeV
was carried out in the low-energy antiproton ring
(LEAR) at CERN. 1 ) In these experiments, the ratio
Rs = 0'++ /0'+ between double- and single-ionization
cross sections, 0'++ and 0'+ of He for antiproton impact
was found to be larger by a factor of two than thatfor proton impact. Some theoretical attempts havebeen made to understand the conspicuous difference
between p-impact and p-impact double ionization. 2- 5 )The studies have shed light on the limitations of the
independent-particle model and on the importance ofelectron correlation in these processes.
Recently, Hvelplund et a1. 6 ) have carried out experiments in a much lower energy regime down to 10 keV
and found that the ratio for protons decreased sharply
as the energy decreased, while the ratio for antiproton increased nearly monotonically. We have investigated the double and single ionization of He andH2 for protons and antiprotons by using a semiclassical molecular-state representation. 7 ) In this method,the electron motion is described quantum mechanically as a two-center molecular-state problem and therelative motion between the two heavy nuclei is described classical mechanically. Discrete molecular electronic states were determined by the configurationinteraction method with the use of Slater-type orbitals
as basis functions. Singly ionized continuum electronic
states were obtained in the fixed-nuclei static-exchange
approximation for elastic electron scattering from theneutral molecule or the molecular ions (HeH)++ and(H2)+' The internuclear distance for H2 was fixed.
Those for doubly ionized states were constructed byusing a perturbation method in which the interelectronic Coulomb potential is the perturbation and theterms up to the first order in the wave function are
retained. For H 2, the nuclear motion was frozen in
the calculation. The adiabatic wave-packet approach,which spans electronic continuum locally, was taken.
A discretized sampling procedure, based on the Gauss
quadrature, was used to select continuum states forthe molecular state expansion method. The numberof channels included in the calculations was 200-300.
The results of the ratios for proton and antiproton impacts for He were reported earlier 7) and our results
successfully reproduced the experimental findings forboth systems. The theoretical rationales for dynamics were: (1) for the antiproton impact, the electronicbinding energy decreases, which is the main mechanism for single ionization. The electron-electron interaction in the presence of antiprotons is of primary
importance in the emission of two electrons, (2) forthe proton impact, the ladder-climbing mechanism isa main mechanism for single and double ionization.
Once one electron is ionized, the second electron feels
more stronger attraction from a He nucleus and it isless likely to lead to double ionization, hence resulting a decreasing ratio as energy decreases. For H 2,
when an antiproton approaches perpendicular with respect to the molecular axis of H 2, the double ionization
probability was found to be a maximum, but when it
approaches parallel to the molecular axis, the double
ionization probability was minimized. These features
closely relate to the electron charge distribution of H2
molecule.
References
1) L. H. Andersen et al.: Phys. Rev. Lett., 57, 2147 (1986).
2) H. Knudsen and J. F. Reading: Phys. Rep., 212, 107(1992).
3) L. Ford and J. F. Reading: J. Phys., B21, L685 (1988).
4) J. McGuire: Phys. Rev. Lett., 49, 1153 (1982).
5) D. R. Schultz, R. E. Olson, and C. O. Reinhold: J.
Phys., B24, 521 (1991).
6) P. Hvelplund et al.: ibid., B27, 925 (1994).
7) M. Kimura, I. Shimamura, and I. Inokuti: Phys. Rev.,
A49, R4281 (1994).

Argonne National Laboratory

95

RIKEN Accel. Prog. Rep. 29 (1996)

2) + dMuon-Transfer Reaction t + dJ-t(2s) ~ tJ-t(nA. Igarashi, 1. Shimamura, T. Shirai,* and N. Toshima
The muon-transfer reaction between hydrogen-likemuonic atoms in excited states,t + dJ.L(n) -+ tJ.L(n) + d,
(1)
is crucial in determining the fraction Qls of dJ.L in the
ground state in a mixture of deuterium D2 and tritium
T 2. 1 ) The physical situation of the muon transfer reaction is quite different depending on whether the dJ.L
atom is initially in the ground state or in an excitedstate, and the theoretical treatment of the muon transfer between excited states is much more difficult for thefollowing reasons.
The degeneracy of excited states requires a muchlarger expansion basis set for the scattering wave function, and leads to an extremely long-range potentialthat decays as the second inverse power of the distance between the charge and the muonic atom. The
fact that the muon transfer is most important at low
energies, where fully quantum mechanical treatment isnecessary, is another cause of the difficulty. All work
devoted so far to reaction (1) involving excited states
is based on the semiclassical treatment in contrast to
the case of a transfer between the ground states , forwhich reliable cross sections are available.
We have developed the hyperspherical coupledchannel or close-coupling (HCC) method and havedemonstrated its efficiency for the ground-state muontransfer process. 2) The greatest advantage of thismethod for rearrangement collisions is that it can treat
different arrangement channels on equal footing. Here,
we report full-quantal calculations for the process (1)in the case of n = 2 by solving the Schrodinger equation directly with the HCC method. The calculations
are carried out at five energies between 0.001 and 0.1
eV. The hyperspherical channels, defined for each fixedvalue of the hyperradius R , that converge to dJ.L( n = 13) and tJ.L(n = 1- 3) in the asymptotic R region are used
to expand the wave function for the total system. For
some values of the total angular momentum J, an enlarged calculation with the channels converging to thedJ.L(n = 4) and tJ.L(n = 4) states included are performed
to confirm the convergence of the cross sections withthe size of the basis set. The cross sections change little, which proves a good convergence. The scattering
equations in the HCC method are solved for J = 0- 10,
and this is sufficient for the converged transfer crosssections. The higher-partial-wave contributions to theelastic cross sections are calculated using an expansion
in terms of atomic orbitals of dJ.L(n = 1- 2) , and thecontinuity of the results from the two methods is good.
The elastic and transfer cross sections in the HCC
method are presented in Fig. 1, and are compared with
Department of Reactor Engineering, Japan Atomic Energy
Research Institute96

other theoretical transfer cross sections calculated insemiclassical approximations. For the elastic cross section, there is no reported work and the comparison is
not made. The RCC elastic and transfer cross sections have similar values at an energy of 0.001 eV, andthe elastic cross section shows a weaker decrease withincreasing energy. The transfer results differ considerably between different methods.

" - " - " -G _~~- -13-. __10 1

C . M . Co ll is ion En e r gy i n e V

Fig. 1. Cross sections for elastic scattering t + dJ-L(2s) -+t + dJ-L(2s) and for muon transfer t + dJ-L(2s) -+ tJ-L
(n = 2) + d. Elastic: open squares, present calculation. Muon transfer: open circles, present calculation;
dotted curve, Solov'ev;3) dot-dashed curve, Menshikov
et al.;4) dashed curve, Czaplinski et al. without electron
screening;5) long-dashed curve, Czaplinski et al. withelectron screening. 5 )In the actual experimental system for the study ofmuon-catalyzed fusion , the triton in the initial channel
in reaction (1) is embedded in a molecule T 2 or DT.
In other words, the actual processes of experimental
interest are
T2 + dJ.L -+ DT + tJ.L
(2)
andDT + dJ.L -+ D2 + tJ.L.
(3)
Thus the muon-transfer reaction (1) occurs under thescreening of charges by two electrons. A comparisonof the transfer cross sections of Czaplinski et a1. 5 ) withand without the electron-screening effect reveals thatthe effect becomes more pronounced as the collisionenergy is lowered. A realistic calculation including it
requires a further study.
References
1) L. 1. Ponomarev: Contemporary Phys. , 31 , 219 (1990).
2) A. Igarashi et al.: Phys. Rev., A50, 4951 (1994).
3) E. A. Solov'ev: Yad. Fiz. , 43 , 138 (1986).
4) L. 1. Menshikov et al.: Z. Phys. D, 2 , 1 (1986).
5) W. Czaplinski et al.: Phys. Rev., A50 , 518 (1994).

RIKEN Accel. Prog. Rep. 29 (1996)

Strong Induced-Dipole-Field Oscillations in an Excited dtJL
Molecule above the tJL (N == 2) Threshold
K. Hino and J. H. Macek*
Investigations on elementary atomic processes for a
dtJ..L molecule are quite important to disentangle complicated phenomena underlying the muon catalyzed fusion (J..LCF) and to understand the general Coulomb
three-body problem beyond the validity of the infinite
nuclear mass approximation. Recently, of special interests are Feshbach resonances and muon transfer processes in the manifolds of N ~ 2, which are thought toplay decisive roles in J..LCF. Such atomic processes relevant to an excited dtJ..L molecule are characterized bya long-range nature of an attractive dipole interaction-0:./ R2 , where 0:. is associated with a dipole moment of
a tJ..L (dJ..L) atom induced by a collision partner d (t) and
R is an internuclear distance. The most remarkablepeculiarity of the dipole interaction manifests itself inthe existence of the infinite number of bound or resonance states bolow a threshold and in the appearanceof oscillations of cross sections above the threshold.
The latter effect is called the Gailitis-Damburg (GD)
oscillation.!) The strong GD oscillation is expected in
dtJ..L since the magnitude of 0:. measured in the muon
atomic unit is about ten times greater than that of ahydrogen negative ion H- gauged in the usual atomic
unit. In this report, we concern ourselves with thisintriguing effect.
We employ the hyperspherical method to analyze
the Coulomb three-body system of dtJ..L since it enables us to apply straightforward to any three-bodysystem irrespective of its mass and charge ratios. The
S-matrix (5') , amenable to the Stark representation,
is obtained by a usual matching procedure. This matrix is furthermore transformed into the S-matrix (S)in the hydrogenic representation by 5 = V(+) 5'V(-)t
with V(±) unitary.!)
In Figs. 1 and 2, we show squared T-matrices corresponding to 5' and 5 for the elastic and inelastic
collisions within the N = 2 manifold of tJ..L from extremely low energy region to relatively higher energy
region. The partial wave for these collisions is limited
to the S-wave and the Lamb shift contribution is taken
into no account. The quantities of ITfl,i/12 of Fig. 1
exhibit oscillating structures nearly above 1 eV. The
oscillations are thought to result from interference ofthe dipole-oscillation phase pertaining to the attractive
dipole channel of tJ..L with several phases belonging to
the upper attractive channels, especially, to the nearest channel of dJ..L. As a result of the above-mentioned
transformation, the T-matrices of Tf',i' in the Stark
representation are mixed up one another to show the
Department of Physics and Astronomy, University of Tennessee and Oak Ridge National Laboratory, U .S.A.

strong GD oscillations of ITj ,i1 2 in Fig. 2.

~ 0.5

0~~1-0-~2~~~~~~~~~

Incident Energy (eV)Fig. 1. The squared T-matrix of ITj' ,i, 12 versus the incident energy in the center-of mass frame measured fromthe tJ.l (N = 2) threshold . The solid line, the dashed2, IT~,_12 and IT.+,_12,
line and the dot line mean IT.+,+ 1
respectively, where + and - stand for the lower andthe higher Stark states within the tJ.l (N = 2) manifold. The arrow at 12.01 eV indicat es the threshold of
dJ.l (N = 2) . The vertical line at 8.24 eV is the Feshbachresonance supported by the attractive dipole potentialof dJ.l (N = 2) .

II
,I

,I

~

N

-

.;:: 0.5 ,
~,

I
1

' I

JI

'

nv

1,\,\

1
I

1
\

l' I I "I In I:

I', I, 1 1,' ,1,'/ ~ 1,1,
1 I 1"

I

d \

~

'I

n

II
11

I
,

I'

• ' I 1\ 'I II
Ii II 'I ' I '{i'1 11 11
,1 , 1 II , I 1 \
1 \
'1'

II
II

I

I

I

,

,

,

,

,

1.1 ."

I I.' :... I (I ' : I: ' ~ i I~ i. i, i ~, !\, 1./ V,/· I" I, ~:", , , "I',1:1 ,I I~! \:: \11 :,' \ if \ ,o ".~ . I .. " ~: "~ ..v, '." " \~ "
10-2

10°

102

Incident Energy (eV)Fig. 2. The squared T-matrix of ITj,i1 2 versus the incident energy in the center-of mass frame measured
from the tJ.l (N = 2) threshold. The solid line, thedashed line and the dot line mean IT2s ,2sI2, IT2p,2P12
and IT2s ,2P I2, respectively, where 28 and 2p stand for theexcited states of tJ.l(2s) and tJ.l(2p) , respectively. The
arrow and the vertical line are the same as in Fig. 1.

References
1) M. Gailitis and R. Damburg: Proc. Phys. Soc. , 82, 192(1963).

97

RIKEN Accel. Prog. Rep. 29 (1996)

Coincidence Measurement of Fragment Ions with Final Charge
State of Projectile in Fast Ion -C 60 Collision
Y. Nakai, A. Itoh, T. Kambara, Y. Bitoh, and Y. Awaya
The interest in the fragmentation of C 60 induced by
the collision with ions, electrons, and photons is recently increasing. 1- 6 ) LeBrun et al. measured the fragment distribution for the collision of fast Xe ions withgaseous C 60 . 1 ) They discussed the fragment ion distribution by a bond-percolation model which is often used
for nuclear multifragmentaiton. The small size fragments come from the multifragmentation phenomenaof C 60 . The multifragmentation is caused by the large
energy transfer and multiple ionization. It is expected
the large energy transfer events can be selected using
coincidence fragment distribution measurements witha projectile final charge state because projectile chargetransfer occurs when the projectile trajectory has anoverlap with C 60 in fast collision. We performed selective measurements of the fragment ion distributions atsuch overlap collisions using the coincidence measurement method with projectile charge transfer.
We used the time-of-fright (TOF) method for fragment ion distribution measurements. The carbon ion
beam of 1.3 MeV lu from RILAC passed through C 60
vapor formed by a heated oven at 420- 450°C. The
mass-to-charge ratio(m/q) of fragment ions was analyzed by a TOF spectrometer located at 90° with respect to the incident beam. The TOF spectra wereobtained using a multi-hit time-to-digital-converter(TDC). The final charge states of projectile ions wereanalyzed by a bending magnet downstream from thetarget area, and projectile ions were detected by a parallel plate avalanche counter (PPAC).
In Fig. 1 we present the total TOF spectrum for
initial charge state 5+ without coincidence. It is similar to the TOF spectrum by LeBrun et al. It has
the peaks for C 60 +, the peaks for C 60 - 2n +, which arethought to be residual cluster ions after evaporationof carbon dimers, and the peaks for small fragments
whose size n is up to n = 15. In the small size fragment, the odd-numbered peaks are more intense thanthe even-numbered peaks up to n = 9 and the peaks
corresponding to n = 11 and 15 are also intense as
seen in the other fragmentation experiments and small
cluster formation experiments. For the other initialcharge state of projectile, we got the similar TOF spectra even though the intensities of small fragments are
more intense with increasing an initial charge state ofprojectile.
Figure 2 shows the TOF spectra in coincidence withthe final charge state in the cases of projectile Kshell electron loss( C 4 + to C 5 + and C 5 + to C 6+) andelectron capture by projectiles with K-shell electron
vacancies (C 5 + to C 4 + and C6+ to C 5 +). Little or no

98

6000

Ceo'

~

;

a

}

4000

1 3
2000
0

0

1000

2000

3000

TOC Channel

Fig. 2. Total TOF spectrum in thecollision of C60 with C 5 +. The
number above each peak shows
the n of en +.

Fig. 1. TOF spectra in the coincidence measurement witha final charge state of projectile.
parent-like heavy fragment ions can be seen here. Only
for the electron loss from projectile C 4 +, we can see
weak peaks corresponding to multiple charged parentlike fragment ions. The odd-even oscillation can bealso seen here though these TOF spectra are quite different from the total TOF spectra without coincidence.
In the case of electron capture in our energy region,a predominant process is that a Is-electron localizedaround a carbon nuclei of C 60 is captured to K or Lshell of the projectile ion. So, the Is-vacancy is createdinside C 60 and it decays through the Auger process.
The Auger process causes the emission of a few electrons, which is recently shown by photo-excitation andphoto-ionization of Is-electron. 6 ) Moreover, the projectile ions can excite and ionize other electrons because the projectile trajectory overlaps with the electron cloud of C 60 . Thus, the electron capture processcauses multiple ionization and excitation of C 60 enoughfor multifragmentation. In the projectile K-shell electron loss, the ionization and excitation of electrons of
C 60 also occur. And the projectile K-shell electron
loss process may produce the Is-vacancy of C 60 because most of such K-electron losses seems to occur
close to a carbon nuclei of C 60 at our incident energy.
So, the projectile K-shell electron loss process can also
cause multifragmentation. The fragment ion distributions seem to depend only on the initial charge stateof projectile.
References
1) T. LeBrun et al.: Phys. Rev. Lett., 72, 3965 (1994).
2) P. Hvelplund et al.: ibid., 69, 1915 (1992).
3) B. Walch et al.: ibid., 72, 1439 (1994).
4) D. Ding et al.: ibid., 73, 1084 (1994).
5) H. Hohmann et al.: ibid., p. 1919.
6) S. Aksela et al.: ibid., 75, 2112 (1995)

RIKEN Accel. Prog. Rep. 29 (1996)

Three-Dimensional Recoil-Ion Momentum Analyses in
8.7 MeV Q7+-He Collisions
T. Kambara, J.-Z. Tang, Y. Awaya, B. D. DePaola, O. Jagutzki, Y. Kanai, M. Kimura,T. M. Kojima, V. Mergel, Y. Nakai, H. W. Schmidt-Backing, and I. Shimamura
We have measured the final electronic state distributions and differential cross sections of singleelectron capture and target single-ionization processes
for 8.7 MeV 0 7 + -He collisions as functions of scattering angle, using high resolution recoil-ion momentum spectroscopy. 1) Information on the final electronic
state is obtained from the longitudinal momentum
component PIIR (parallel to the projectile direction) of
the recoil ions and that on the projectile scattering
angle from the transverse momentum component P...LR.
The details of the work have been reported elsewhere. 2 )The setup and the preliminary results were reported
previously. 3) A collimated 8.7 MeV 0 7+ beam fromthe RILAC was intersected with a target of supersonic He jet from a pre-cooled gas. Performing a
recoil-projectile coincidence, we have determined thethree-dimensional recoil-ion momentum for selected final projectile and recoil charge states.
The experimental resolution of the longitudinal momentum component was about ±O.5 a. u. and that of
the transverse component was about ±O.2 a.u. whichcorresponds to an angular resolution of about ±1.5 x
10- 6 rad for the projectile scattering angle.
For the pure single-electron capture(1)

the PIIR distribution is displayed in Fig. l(a) and thedifferential cross sections dcr / dP...LR is displayed in (b).
In single-electron capture, the dominant contributions
to capture were found to be those from the n = 4 andhigher states. Figure 1 (b) shows the correspondingtransverse momentum distribution integrated over thewhole peak structure in Fig. l(a).
A semiclassical molecular-state-expansion method
was used to calculate the electron capture cross sections. The recoil momentum distribution was obtainedby using the WKB approximation for the heavy particle motion. We carried out five-channel calculations,the results of which are included in Fig. 1. The crosssection for transfer to the n = 5 state is found to be
dominant, whereas the n~4 states are not much populated. The differential cross section convoluted by theexperimental resolution qualitatively agrees with thepresent experimental cross section, although the absolute value of the maximum differential cross section islarger than the experimental value by a factor of about
2.5.
The transfer ionization process(a) Longitudinaln= 2 34 00

rJ)

'E

I

~ 500

o

-

I ~~
.- fi\.;-4f-----1..__",.,..••..,.....

____,..•.",..#11<26

Resolution

II-2
P//R (a.u.)(b) Transverse• Experiment-Theory- - -Convoluted
Resolution
H

....

1000
rJ)

'E

500

5

o

OL-L-~2~~4~~~6~~8~~0P.lR (a.u.)

Fig. 1. Measured recoil-ion momentum distribution forthe pure single-capture reaction channel: (a) displays
the longitudinal momentum PIIR distribution and (b)the differential cross section as a function of the transverse momentum P..LR. The n-values in (a) correspondto the final principal quantum number in 0 6.+ (lsnl).
Solid line in (b) shows the results of the close-coupling
calculations and dashed line shows the results convoluted by the experimental resolution.

(2)
was found to proceed through the single-electron capture accompanied by a single target ionization whichmainly populates final n = 2 to n = 4 states. The
contribution of another possible process, the doubleelectron capture followed by auto-ionization of the projectile, is relatively small. It was also found that thedifferential cross section (transverse momentum distribution) differs significantly from the pure single capture cross section.

References
1) J. Ullrich, R. Dorner, V. Mergel, O. Jagutzki, L. Spielberger, and H. Schmidt-Backing; Comments At. Mol.
Phys., 30, 285 (1994).
2) T. Kambara et al.: J. Phys. B: At. Mol. Opt. Phys., 28 ,4593 (1995).
3) T. Kambara et al.: RIKEN Accel. Prog. Rep., 28, 75(1995).

99

RIKEN Accel. Prog. Rep. 29 (1996)

Intercombination Lines in Highly Charged Ions
P. Bengtsson, K. Ando, T. Kambara, Y. Kanai, T. M. Kojima, Y. Nakai, Y. Awaya, L. Engstrom,
R. Hutton, I. Kink, 1. Martinson, and B. Nystrom
The spectra of heavy and highly charged ions areoften line-rich making analyses of such spectra complicated. Most of the levels in such ions are very shortlived, that is the lifetimes are in the order of ps. The
beam-foil technique offers a possibility to study theions excited by the foil at well-defined distance fromthe excitation point. Since the ions are moving witha well-defined velocity, that distance is equivalent toa time after the excitation. The distance can be chosen such that all the fast transitions have aIrpost completely decayed and thus they have become weak. Thus
only lines originating from long-lived levels, mostly socalled intercombination lines, which are lines originating from transitions where the initial and final state
have different spins, remain in the spectrum. Such aspectrum is referred to as delayed spectrum. I)
The work reported here concerns ions of Kr, Y, Zr
and Nb. The energy of these ions were 1.67 and 2
MeV lu and they were obtained from RILAC. Measurements of the spectra were made at a delay-time of
approximately 500 ps. All the intercombination lines
we have been concentrating our attention on, the Mglike intercombination line 3s 2 I So-3s3p 3PI, the AI-like3s 23p 2PI/2-3s3p2 4P 1 / 2 and 3s23p 2P 3/ 2-3s3p 2 4P5/2
lines and the Si-like 3s 23p2 3P 1 -3s3 p 3 5S 2 and 3s 23p2
3P 2-3s3p3 5S 2, appear within a wavelength region of
approximately 20 A for these elements.
The relative intensities of each line in the spectra at
the two different energies depend on the charge state
distribution of the element at that particular beam energy. The lines we observe in these "delayed spectra"
are most likely intercombination lines or other forbidden lines exhibiting a substantially longer lifetime than
the so-called allowed transitions. These two features
are used to support the identifications.
Our observations of Mg-, AI- and Si-like intercombination lines agree well with the observations in thesequence for the Mg- and AI-like ions; that is, thewavenumbers follow a smooth trend. However they100

seem to disagree with the transition energy reported
for the Si-like 3s23p2 3P I -3s3p3 5S 2 and 3s23p2 3p 23s3p3 5S 2 lines in Mo,2) see Fig. 1. The earlier observations have been based on comparison with Ref. 3
and have been approaching agreement with the calculated values. Our observations disagree with both Ref.
2 and 3. Even though not involving the theoreticalvalues in the discussion, it is clear that something is
not right. The observations in Ti IX-Br XXII in theplot are done by Trabert et a1. 4,5) This will be subject
to further investigation for higher Z elements.

t .

Qo-c

t

200

, , . f ,fo . .. . ..... ... . .. .. .... .......... . '...... . . ~.
I

-2 00
l

10

15

20

25

Fig. 1. Isoelectronic comparison of wavenumbers reducedby the theoretical value by Huang. 3 ) The dotted line isto guide the eye. ( is the effective core charge seen by
the jumping electron. (j o-c is the difference between observed and calculated wavenumbers. The wavenumbers
are in em-I.

References
1) E. Thibert: Physica Scripta, 48, 699 (1993).
2) C. Jupen et al.: ibid., 44, 562 (1991).
3) E. Trabert et al.: J. Opt. Soc . Am. , B5, 2173 (1988).
4) E. Trabert: Phys. Rev. , A47, 3805 (1993).
5) K.-N. Huang: At. Data Nucl. Data Tables, 32, 503(1985).

RIKEN Accel. Prog. Rep. 29 (1996)

Observation of a Systematic Deviation between Experimental
and Theoretical Lifetimes for the 3s3p 3 PI Levelof High Z Mg-like Ions
R. Hutton, L. Engstrom, S. Huldt , B. Nystrom, I. Martinson , K. Ando, P. Bengtsson, T. Kambara,
Y. Kanai, T. M. Kojima, Y. Nakai, and Y. Awaya
In a previous reportl ) we discussed beam-foil measurements of the 3s3p 3 PI lifetime for Mg-like Zr and
Nb. We hinted at a possible discrepancy with the currently available theoretical values. During the recent
year measurements have been made on a number ofother Mg-like ions and this discrepancy has been con-

50
45

II

40

f 1

35

",,~30

'~
'"

<.Jo

25

;;:
20

15
10

Fe XV

10

15

G. XX Kr XXV Nb XXX

20

25

30

35

effective charge, (Fig. 1. This shows a comparison of the experimental andtheoretical scaled oscillator strengths for 3s 2 1 So-3s3p
3 PI spin-forbidden transition in Mg-like ions. The filled
circle data points are measured at RIKEN. The twotheoretical curves are those reported by Huang andJohnson 5 ) and Cheng and Johnson. 6 ) Cheng and Johnson present calculations for a few elements over a large
range of atomic numbers, and with larger intervals. (isthe effective core charge seen by the jumping electron.

Table 1. Comparison of the experimental 3s3p 3P I lifetimes with those calculated by Curtis. 4 )Ion
Ni XVIr XXV
Y XXVIIIZr XXIX
NbXXX

T exp

[ns]

10.8 ± 0.2
1.24 ± 0.05
0.72 ± 0.07
0.55 ± 0.03
0.45 ± 0.025

Tth e ory

[ns]

12.5
1.54
0.878
0.07430.637

firmed. Measurements have been performed for Mglike Ni, Kr and Y and we have re-measured the Zr andNb cases. The measurements were done using beams
of 0.7 MeV lu Ni and 2 MeV lu Kr , Y , Zr and Nb provided by the RILAC accelerator. The beam-foil set up
described earlier 2 ) was modified to account for background problems from beam-related electrons as discussed by Hutton et a1. 3 ) Table 1 shows a comparisonof our 3s3p 3 PI lifetimes with the values obtained by
Curtis. 4 ) The deviation between experiment and theory is clearly seen in Fig. 1 where our scaled oscillator
strength is shown along with the theoretical values ofHuang and Johnsson 5 ) and Cheng and Johnson. 6 )References
1) R. Hutton et al.: RIKEN Accel. Prog. Rep., 28, 69(1995).
2) K. Ando et al.: J. SpectT'. Soc. Jpn., 41, 370 (1992).
3) R. Hutton et al.: to be published.
4) L. J . Curtis: Physica Scripta, 43 , 137 (1991).
5) K.-N. Huang et al.: Nucl. Instrm . Methods Phys. Res.,
B9, 503 (1985).
6) K . T. Cheng et al.: Phys. Rev., A16 , 263 (1977).

101

RIKEN Accel. Prog. Rep. 29 (1996)

Problems Caused by Beam-Related Electrons in Beam-Foil
Lifetime Measurements
R. Hutton, 1. Engstrom, S. Huldt, B. Nystrom, 1. Martinson, K. Ando, P. Bengtsson,
T. Kambara, Y. Kanai, T. M. Kojima, Y. Nakai, and Y. Awaya
During our studies of the 3s3p 3 PI lifetime for Mglike ions l ) we have found a number of problems causedby beam-related electrons. For example the cuspelectrons for the 2 Me V / u beams of Kr, Y , Zr andNb used will have an energy of 1.066 Ke V and thebinary-encounter peak will be at 4.264 keY. It appears that when such electrons hit the entrance slit of
the 2.2 m grazing incidence spectrometer a high photon background is generated. This rate depends on
the position of the foil with respect to the entrance
slit. We could remove the background by applying amagnetic feild over the spectrometer slits, see Fig. 1.
We have also used an auxilIary slit arrangement fixed
on the spectrometer slit to eliminate this backgroundproblem. The 2nd problem, related to these electrons,
is that of beam normalisation. As the foil is moved
away from the Faraday cup the fraction of electrons in
the beam will change (angular distribution, scatteringetc.). This means that a constant current from the accelerator will not give constant data acquisition times
for different foil positions. We have studied this during periods of stable accelerator operation. Throughthese studies we could generate a correction function.
We have also eliminated the problem by using a secondary fixed foil in front of the Faraday cup. In thecases where we have used both methods to measurea decay curve the extracted lifetimes have agreeded.
There is a 3rd background problem which is not yet
solved. This is a very intense but short lived background at or close to the foil. It is assumed that this is
generated either by electrons hitting the spectrometer
slit or X-rays from the foil. We will attempt to reduce
this by putting a bias ring in front of the slits and bytilting the foil holders.

102

(c)
o

o

o

(a)

0

o

o
o

70

80

90

100 110 120 130 140 150 160

distance travelled by foil, mm

Fig. 1. Decay curves for the 3s 2 lSo-3s3p 3 PI transition in
Nb 29 + (197.68 A). Curve (a) shows the intensity decayof prompt background near the foil, recorded at a position where no spectral lines were observed. Curves (b)and (c) are taken from lifetime measurements withoutor with the external magnetic field, respectively. In thelatter case the background is reduced to practically thedetector dark rate.

References
1) R. Hutton et al.: to be published.

RIKEN Accel. Prog. Rep. 29 (1996)

Beam-Foil Spectra of Highly Charged, Highly Excited
Neon Ion in Visible Region
K. Ishii, Y. Kimura, T. Nishida, and K. Ando
Atomic structure and spectra of highly charged raregas ions have received increasing interest from theviewpoint of diagnostics of fusion-oriented high temperature plasma. The low lying allowed transitions
have been well studied in the conventional dischargesources. However, there is still a lack of informationon the spectra of high lying and/or multiply excitedtransitions. The beam-foil method is efficient for producing these states.
The beam-foil spectra of Ne ion at energy of 0.5 and
1.0 MeV /u from the linear accelerator RILAC wererecorded in the range between 2000 and 5500 A. Photons emitted from the Ne ion beam were viewed in theperpendicular direction of the beam, dispersed by amonochromator (f = 25 cm) and detected by a photomultiplier. Higher spectral resolution was achieved by
the refocusing method. Most of the lines are classified
due to the transitions of high n , .e-levels. The most intense lines in each line groups are those with possible
highest f transitions. Some of the satellite lines areclassified as multiply excited state transitions.
We have first calculated wavelengths from the hydrogenic term energy for n, .e-level given as
R(2 {TH=----:;;,2

Q2(2

1+~

yrast transition 2s7i-2s8k. A line at 3681 A is classified
to n = 10 - n = 12 transition in He-like Ne IX. A few
weak lines on the larger wavelength side of the 2s7i2s8k line are probably due to multiply excited transitions. Two lines around 3750 A are 2s7f-2s8g, 2s7d-2s8f
or 2s7g-2s8f.
Most of the intense lines covered in the present work
are identified as transitions between high n, .e-levels
with D.n = 1, where n is ranging from 6 to 10 in
Ne VII, Ne VIII, Ne IX and Ne X. Detailed analysis
will be given elsewhere. 4 )Neon O.5MeV/arnu

1000

(a)

>.

~

soo

0
3600

(n

3700

3800

3900

3) }
j+l/2-4

..>0:

~

(b)

where R is the Rydberg constant and ( is theion charge. The transition probabilities were also
calculated.!) The wavelength thus obtained with thehighest possible .e value is in good agreement with themost intense line in each observed line group. As thenext step we have taken into account the core polarization effects. 2 ) Finally both energy levels and transition probabilities were computed by use of the atomic
structure calculation code (HXR). 3)
In Fig. l(a) a partial spectrum of 0.5 MeV /u beam
immediate downstream of the foil is shown. The lines
are classified to the transition of Is 2 2s7f-ls 2 2s8f as
indicated, where £ ranges from 3 to 7. The lower
Fig. l(b) shows the spectrum calculated by the HXR
method. In the calculation the following configurations
were included together with the configuration interactions in Be-like NeVIl:

2s6.e + 2s7.e + 2s8£ + 2s9.e + 2p4.e + 2p5.e.
The levels with f :::; 6 in n = 8 manifold are largely perturbed with the nearby lying configuration 2p5.e levels,and the lines of the transition 2s7.e' -2s8.e with £' :::; 5and £:::; 6 are shifted appreciably from the line of the4000

Wavelength (A)

~

r::

~
E

~

.2

'"

>.

~

:5

]

~ .

0

..=d::
OIl C'il .g~ '1il

~ ~

~ f-

~
3600

3700

3800

3900

4000

Wavelength (A)Fig. 1. Partial spectrum of Ne ion. (a) Observed and (b)calculated.

References
1) H. A. Bethe and E. E. Salpeter: Quantum Mechanics ofOne- and Two-Electron Atoms, Springer-Verlag, Germany (1957).
2) B. EdIen: in Handbuch der Physik, Vol. 27, ed. S.
Fliigge, Springer-Verlag, Germany, p. 80 (1964).
3) R. D. Cowan: The Theory of Atomic Structure andSpectra, University of California Press, U.S.A. (1981).
4) K. Ishii, Y. Kimura, T. Nishida, and K. Ando: to besubmitted in Physica Scripta.

103

RIKEN Accel. Prog. Rep. 29 (1996)

L X-Ray Emission Spectra of Copper
K. Kawatsura, R. Takahashi, H. Kageyama, T. Kambara, M. Oura,
T. Papp, Y. Kanai, and Y. Awaya
The structure of the K X-ray diagram emission linesof the 3d transition elements has been the subject ofnumerous studies. Recently, we have reported thatbroad satellite peaks are observed on the high-energy
side of the L X-ray diagram emission lines in 3d transition metals (Cr, Mn, Fe and Co) by 1.1 MeV N- and0.85 MeV Ne-ion impacts and the L0: 1,2 lines are significantly shifted to lower energies. 1)
In this report we present the results of the highresolution measurement of L X-ray emission spectrafrom a Cu target produced by 0.73 MeV/nucleon He,
Si and Ar ions at the RILAC. A well collimated beam
« 1 x 1 mm2 ) was incident on a Cu foil target of 0.2-2/-Lm thickness. The L X-ray spectra were measured byusing a broad-range crystal spectrometer with a flat
RbAP crystal (2d = 2.612 nm).2)
Figure 1 shows L X-ray spectra from a Cu foil target by 0.73 MeV/nucleon He2 +, Si 5 + and Ar 6 + ions,
respectively. Since the L7] and LL lines are found to berelatively weak, we focused our attention on the energy
region of the L0: 1,2 and L,61 lines. The peak energies
of L X rays obtained at the RILAC with heavy ionswere calibrated with those produced by H- and He-ion
impacts at the JAERI-TIARA.

C
..J

~

>
w

(900-923 eV) was attributed to the radiative Auger effect (RAE) or radiative electron rearrangement (RER).
These are frequently observed in the K X-ray transition spectra, but have not been observed in the L
X-ray transition. We consider that the complicatedstructures above L0: 1,2 and L,61 lines are the satellite
and hypersatellite lines due to multiple L- and M-shellionization.
Full understanding of the origin of the broadening of
the L0: 1,2 line to a lower energy is difficult and awaits
for future studies. However, we have tried to compare the experimental spectra with the calculated ones
based on the multiconfiguration Dirac-Fock method(GRASP code).3) Table 1 shows the resulting peak centroid energies of calculated transitions of L0: 1,2 and L,61
X-ray diagram and satellite lines for a Cu free atom.
It is noted that the centroid energy of L0: 1,2 satellite
lines with one 3d electron vacancy shifts by 1.6 eV to alower energy than the diagram lines. This explains thebroadening to lower-energy side in the L0: 1,2 spectrum
produced by heavy-ion impacts. The transition energy
with initial two 3d vacancies is the same as the energyof the diagram line. A larger energy shift in L,61 Xray transition was found in the calculation; -1. 9 and-1.0 eV for one and two 3d vacancies, respectively.
However, it is difficult to discuss L,61 spectra observed,
since the Cu L3 and L2 absorption edges lie at 933 and951 eV, respectively, and L0: 1,2 satellite lines are overlapped in this energy region. They seem to hide thelow-energy shift of the L,61 lines .
Table 1. Averaged centroid energies in eV for Cu L0: 1 ,2and L,Bl X-ray diagram and satellite lines calculated by
Dyall et a1. 3) using the MC-DF method (GRASP code).

~

~

«

..J

w

£t:

900

X-ray

950

1000

Transition

Number of 3d electron vacancy
o
1
2
930.0
928.4
930.1
LO: 1 ,2 2p3/ 2- 3d3/2,5/2
950.1
948.2
949.1
L,Bl
2Pl/2- 3d3/ 2

x- RAY ENERGY (eV)Fig.
1.
L X-ray spectra of Cu produced by 0.73
MeV /nucleon He 2+, Si 5+, and Ar 6 + ion impacts.

In cases of Si- and Ar-ion impacts, we found a very
weak and broad band at the low-energy side of theL0: 1,2 line, and found more complicated structures at
the high-energy side of L0: 1,2 and L,61 lines. We also
found broadening of the L0: 1,2 line to a lower energy,
but no shift of the peak energy. The weak band

104

References
1) K. Kawatsura, K. Ozawa, M. Terasawa, K. Komaki, andF. Fujimoto: Nucl. Instrum. Methods Phys. Res., B75 ,
28 (1993).
2) A. Hitachi, H. Kumagai, and Y. Awaya: ibid., 195, 631(1982).
3) K. G. Dyall, I. P. Grant, C. T. Johnson, F. A. Parpia,
and E. P. Plummer: Comput. Phys. Commun., 55 , 425(1989).

RIKEN Accel. Prog. Rep. 29 (1996)

Angular Distribution Measurements of X-Rays from
Multiply Ionized Atoms
T. Papp, Y. Awaya, T. Kambara, K. Kawatsura, T. M. Kojima, Y. Nakai, and M. QuraIn heavy-ion impact the dominant process is themultiple ionization of target atoms. To calculate theionization cross sections for the L-shells two competing
methods are used,1) namely the ECPSSR-BC theory
and the coupled channel calculation method. However, in the determination of ionization cross sections
the knowledge of decay parameters, like fluorescence
yields, X-ray branching ratios and Coster-Kronig transition probabilities are necessary ingredients. 1) The
available information on these parameters is very limited and strongly depends on the distributions of thevacancies on various shells. 2) A series of measurements
was carried out to study the L-shell X-ray spectra of
medium and heavy elements by Si(Li) detectors, having moderate resolution compared to crystal diffraction spectrometers. The presence of many satellite
lines makes the analysis of X-ray spectra complicated,which indicates a need for high resolution measurements. Generally, in the case of multiply ionized atoms
the magnetic substate population of the initial state of
the X-ray transition is nonstatistical. This may resultin the anisotropic angular distribution of the Ll andL2 X-rays. Additionally in the case of the L3 subshell both the initial and final state can be aligned;
as a consequence some X-ray transitions are expected
to have large polarization and anisotropy in angular
distribution. 3) We have developed a formalism to describe the angular distribution and polarization of Xray transitions between aligned initial and aligned final
states.
To study this possibility, and to measure the L-shell
X-ray yield ratios, an angular distribution measurement was carried out on a terbium target. The experimental arrangement was similar to an earlier measurement reported in Ref. 4. The target atoms were
ionized by Ar ions from the RILAC, at 13.2, 29.4, 52,
and 80 MeV incident energies. The target X-rays werediffracted by LiF(200) and (220) crystals and a position sensitive proportional counter was used to detect
the X-rays. Reference spectra were also recorded following X-ray excitation from an X-ray tube and with
28 MeV N projectile from the RILAC as well. The
relative intensity of the X-rays differs largely from the
X-ray excited case. Typical spectra are presented for
the Nand Ar projectile impact in Fig. 1. The L-ycomplex was hardly discernible as an indication of thestrong multiple outer shell ionization.
In the evaluation of the X-ray spectra difficulties
arose from the determination of the spectrometer

La

Non Th
L~

....J

n

W

z
z

:2 104

C,)
~

L.I.I

Q.

Ly

~
Z

::::>
0

u

10 3

200

400

600
Aron Tb

uJ 104
Z
Z

~
C,)
c:::

W

Q.

~ 103
o
Z

::::>

u

200

400

600

CHANNEL NUMBER

Fig. 1. The L X-ray spectra of terbium following 28 MeV
N (upper part) and 80 MeV Ar (lower part) ion impact.

transmission function, and the polarization sensitivityof the apparatus. A method for the determination of
the polarization sensitivity was developed. It is basedon the strong energy dependence of the largely polarized bremsstrahlung radiation of an X-ray tube. The
evaluation of the data is in progress.
References
1) R. Mehta et al.: 1. Phys., B28, 1187 (1995).
2) D. F. Anagnostopoulos et al.: ibid., p. 47.
3) T. Papp and L. Kocbach: 1. de Physique, C9, 245(1987).
4) T. Papp, Y. Awaya, A. Hitachi, T. Kambara, Y. Kanai
and T. Mizogawa: RIKEN Accel. Prog. Rep., 24,47; 48(1990); T. Papp, Y. Awaya, A. Hitachi, T. Kambara,
Y. Kanai, T. Mizogawa, and 1. Torok: 1. Phys., B24,
3797 (1991).

105

RIKEN Accel. Prog. Rep. 29 (1996)

Absolute Cross Sections for Charge Capture from
Rydberg Targets by Slow Highly Charged Ions
B. D. DePaola, M.-T. Huang,* S. Winecki,* M. P. Stockli,* Y. Kanai,
S. R. Lundeen,** C. W. Fehrenback,** and S. A. Arko*
We measured absolute charge capture cross sections
in collisions of slow highly charged xenon ions withlaser excited Rydberg Rb(10f) atoms. 1 ) The cross sections were measured for scaled projectile velocities
vpjve from 1.0 to 6.0, and for projectile charge of8, 16, 32, and 40, where vp is the projectile velocity and Ve the orbital velocity of the Rydberg electron. The experimental setup is schematically shownin Fig. 1. A collimated beam of xenon ions from theKansas State University Cryogenic Electron Beam Ion
Source (KSU CRYEBIS) intersects a thermal beam of
excited Rb(10f) atoms in a collision chamber. Afterinteracting with a Rb target, the ion beam is electrostatically deflected by a pair of parallel plates onto a
two-dimensional position-sensitive detector (PSD).

Xe q + + Rb(1 Of)
35

•

fIJ

30

1I

25
u

-0

•

r
•

T

q=16
q=8

~

1
•
1 •T T
1 •1

N

E

q=40
q=32

•

20

g. 15

f

I

u

l! I

t:l

,

t f
L

10

II

~-

!

5

t

•f

oo

•

I.I.

2

i

!

•-*

~

i

3

4

5

i

!
6

V/V e
hu,

Fig. 2. Absolute charge capture cross sections as a function of scaled projectile velocity (vpjve ). Error bars are
relative. Absolute uncertainty is about a factor of 3.
Fig. 1. Simplified overview of the experimental apparatus.

A resistively heated oven at the bottom of the collision chamber produces a beam of Rb atoms. The
collimated beam passes into the region where collisions with the ions take place and is then collected
on a surface cooled by liquid nitrogen. In the interaction region, the Rb beam is stepwise excited to highRydberg states by three cw lasers; (1) a single mode
tunable diode laser at 780 nm, (2) a Nd:YAG pumped
F -center laser at 1530 nm, and (3) an Ar-ion laserpumped Ti:sapphire laser at 755 nm.
Obtained absolute capture cross sections are shownin Fig. 2. Error bars show the relative error in Fig. 2.
Absolute uncertainty is about a factor of 3. The crosssections seem to reach a plateau at the lowest velocities
and drop rapidly as the velocity is increased. These

Department of Physics, Kansas State University, U.S.A.
Department of Physics, Colorado State University, U.S.A.

106

behaviors are explained qualitatively by a classical theory such as the Bohr-Lindhard model. In the BohrLindhard model,2) a capture cross section is given by
for Vs < (4q) 1/ 4
(j = 11'q3n4~-7
for Vs > (4q)1/4(j= 1611' qn 4

where q is the projectile charge, n is the principal quantum number of the target electron, Vs = vpjve , and thecross section is expressed in atomic units. Our results
are in good agreement with this model.
References
1) B. D. DePaola et al.: Phys. Rev., A52, 2136 (1995).
2) J. S. Briggs: Proc. Niels Bohr Centennial Conference,
North-Holland, Amsterdam, p. 183 (1985).

RIKEN Accel. Prog. Rep. 29 (1996)

Optogalvanic Diode-Laser Spectroscopy in Hf I
W. G. Jin, T. Minowa, H. Uematsu,* H. Katsuragawa, and M. Hies
Laser spectroscopy has been proved to be a powerful technique to study nuclear deformation andmoments. 1) Using RIKEN cyclotron facility, now weare performing a systematic laser spectroscopic studyof Hf unstable isotopes. However, spectroscopic information about stable isotopes is necessary for unstable nuclear spectroscopy. Since Hf is a refractory element, it is difficult to produce its atomic beam. Therefore, it is particularly of challenge from the viewpointof laser spectroscopy to introduce a simple method
for producing Hf atomic beam and develope convenient laser spectroscopy, for instance, using a diodelaser rather than an expensive and complicated ring
dye laser. This paper reports convenient optogalvanic
diode-laser spectroscopy in Hf 1.
A Hf galvatron was used in this experiment. Hf
atoms were produced by Ar and Ne-ion sputtering in agalvatron. We used a 785-nm single-mode diode laser
with a power of 3 m W. Temperature and current of
the diode laser were controlled by a controller. The
frequency scanning was achieved by modulation of thecurrent. The laser beam was chopped at a frequency
of about 500 Hz by a mechanical chopper. The laserinduced optogalvanic signal was detected and fed into
a lock-in amplifier. Laser frequency calibration wasmade by recording the transmission peaks through ahome-made confocal Fabry-Perot interferometer witha free spectral range of 300 MHz.
Figure 1 shows a measured optogalvanic spectrumof the 784.5-nm transition from 5d 26s 2 1D2 to 5d6s 26p

10
en'c:::I

.e~
.~
s::

5

<)

.§
~

s::

01)

Vi
10
Laser Frequency (GHz)20

Fig. 1. Measured optogalvanic spectrum of the 784.5-nm
transition in Hf I. A peak of 180Hf is labeled with theisotopic symbol and others are the hfs peaks of 177Hf
and 179Hf.

3p 1 in Hf 1. The FWHM of peaks is about 700 MHz,
mainly from the Doppler broadening. The peaks of
180Hf and 178Hf isotopes are overlapped and this showsthat the isotope shift is smaller than 700 MHz for theisotope pair of 180-178. This result agrees with thatmeasured for other d P transitions. 2) The hfs peaksof the odd-isotopes , 177Hf and 179Hf with the nuclear
spin 7/2 and 9/2 , respectively, are clearly observed.
This is the first optogalvanic diode-laser spectroscopy
in Hf 1.
'7

References
1) W. G. Jin et al.: Phys. Rev., A52, 157 (1995).
2) D. Zimmermann et al.: ibid., A50, 1112 (1994).

Tokyo Gakugei University

107

RIKEN Accel. Prog. Rep. 29 (1996)

Measurement of the Isotope Shift in Fe by
Resonance Ionization Spectroscopy
T. Minowa, K. Hamada,* H. Uematsu,** W.-G. Jin, and H. Katsuragawa
Optical measurement of the isotope shift in an element allows us to obtain information on nuclear
deformation of the element. In a previous report
we described resonance ionization spectroscopy of
Fe and mass separation of three stable isotopes of
Fe using a two-stage acceleration time-of-flight mass
spectrometer. 1) As a next step we have measured theisotope shift in Fe and determined the relative changes
in mean square nuclear charge radii 8 < r2 >.
Fe atomic beam was generated by laser ablation of
an Fe target in a vacuum chamber. The second harmonic radiation of a YAG laser (Quanta-Ray GCR-ll)
was used for laser ablation. Continuous cleaning of thesurface of the Fe target with a small polisher was carried out for stable supply of the atomic beam.
Fe atoms were ionized by focused radiation of adye laser tuned to the z 5D 4 - a5D4 transition of Fe(385.991 nm). Generated Fe ions were accelerated andmass-separated through the drift region of the mass
separator, resolving power of which was about 400.
Mass-separated Fe ions were detected with a ceratron.
Outputs of the ceratron detector were amplified andacquired with a digital oscilloscope (Hewlett Packard
54522A) triggered by radiation ofaXeCI excimer laser
which pumped the dye laser. The waveform acquiredwith the 54522A was sent to a computer through the
GPIB bus and recorded as TOF spectrum.
Resonance ionization spectra of the three stable isotopes, 54Fe, 56Fe, and 57Fe, were obtained as follows.
In isotope shift measurements the computer functioned
as a set of three multi-channel scalers which counted
54Fe, 56Fe, and 57Fe isotopes, respectively. Because
the dye laser scan was controlled by the computer, thechannels of the scalers correspond to the wavelength
steps of the dye laser radiation.
Figure 1 shows the resonance ionization spectrumof 56Fe. Peak wavelengths of the spectra were determined by the least-squares fitting. The normal mass
shift was subtracted from the observed isotope shift in
Fe. The relative 8 < r2 > was calculated from the residual isotope shift. The residual isotope shift contained
the specific mass shift and the field shift. Although it
was reported that the specific mass shift in Fe is small
compared with the field mass shift, the former causes
uncertainties in the relative 8 < r2 >.
The relative 8 < r2 > is plotted against the mass
number of Fe (Fig. 2). The solid line denotes the value
calculated by the droplet model. Good agreement be-

Faculty of Science, Toho University
Tokyo Gakugei University

108

I.--C/'J
~
~

..
I

I

70~

-

60r-

-

50r-

-

Z

:::J
~

~

'-"

C/'J
~

Z

:::J
0

U

Z

0

~

40 r- •• I
-0.001

I

I

-

0.001
0
DETUNING (nm)Fig. 1. Resonance ionization spectrum of 56Fe.

1

.---

N

~
t-

'-"

0

~

V

K>

-1

54

56

58

MASS NUMBER
Fig. 2. The relative changes in mean square nuclear radii
8 < r2 > in Fe are plotted against the mass number ofFe.

tween the two suggests that nuclei of the stable isotopes of Fe are scarcely deformed.
References
1) H. Katsuragawa et al.: RIKEN Accel. Prog. Rep., 27,
70 (1993).

RIKEN Accel. Prog. Rep. 29 (1996)

Knight Shift for 13 0 Implanted in Pt
K. Matsuta, M. Tanigaki, M. Fukuda, T. Minamisono, Y. Nojiri, H. Akai,* M. Mihara, K. Minamisono,
T. Fukao, K. Sato, Y. Matsumoto, T. Ohtsubo, S. Fukuda, S. Momota, K. Yoshida, A. Ozawa,
T. Kobayashi, 1. Tanihata, J. R. Alonso,** G. F. Krebs,** and T. J. M. Symons**
The Knight shift K and the spin relaxation time Tlfor interstitial impurities implanted in metals are important clues to the electronic structure of the metals.
Among the metals, Pt is known to be unique having avery low local electron density around the Fermi level
for interstitial impurities, and therefore, having long
Tl and small K. Pt is often used for the magnetic
moment measurements because of this advantage. It
is important to measure Knight shifts systematicallyfor better understanding of the electronic structure inside metals. Because of the recent development of thetechnique of polarized radioactive nuclear beams , thechoice of probe nuclei now becomes much wider. In
the present experiment, we measured the Knight shift
and the relaxation time of the proton drip-line nucleus
13
0 (I7r = 3/2-, T 1 / 2 = 8.6 ms) through the combined technique of polarized beams and the j3-NMR
detection.
Polarized 13 0 nuclei were produced through the
130 MeV/nucleon 16 0 + 9Be at the RIKEN Ring Cyclotron and were separated by the RIPS (RIKEN Projectile Fragment Separator). Thus purified nuclei werethen slowed down by an energy degrader and were implanted in a Pt foil placed in a strong magnetic field
Ho = 4.0 kOe to maintain the polarization createdin the collision. NMR of 13 0 was observed by meansof asymmetric j3-ray emission. Polarization effect isrecorded as a function of time in order to measure T 1 .
To measure Knight shift K , NMR spectrum was also
observed for 13 0 in an ionic crystal MgO.
As a result, a preliminary value of TIT was obtainedfor 13 0 in Pt to be (2.90 ± 0.65) Ks. A preliminary
value of Knight shift was obtained from the NMR Spectra shown in Fig. 1 to be K = +(4.23 ± 0.14) x 10- 3 .
The Tl T for 13 0 in Pt is unusually small comparedwith other impurities in Pt. As expected from theunusually small TIT, the K for 13 0 is also unusuallylarge. The present results strongly suggest that theelectronic structure around 13 0 in Pt is unusual compared with other cases and the local density at Fermi
level must be huge.
In order to explain the present results , the electronic structure was calculated for the second-period
main group elements in Pt in the framework of
the local spin density approximation of the density functional theory, using the super-cell methodin the Korringa-Kohn-Rostoker (KKR) band-structure

3a) 130 in Pt
2

~
Q)

OJ
C

co

0

~

0

~
Q)

E 3
E
>en 2

«

>~

c6.

Or---~~--------~-+------------

2810 2815 28202825 2830 2835 2840
Frequency (kHz)Fig. 1. NMR spectra of 13 0 implanted in Pt and MgO.

0.007
0.006
.t::

•

Theory

0

Exp.

Be

B

0.005

:c
0.004
(J)
EC) 0.003·c 0 .002
~

0.001
0.000
-0.001

Li

C
N
Nuclei0F

Fig. 2. Experimental and theoretical Knight shifts forinterstitial impurities in Pt.

calculation. The theoretical values are shown in Fig. 2
with the experimental Knight shifts. Although the calculation is still preliminary, agreement with the present
data is remarkable. It is concluded that the short Tl
and the large K for 13 0 in Pt can be understood by
the large local electron density around the Fermi level,
which is well reproduced theoretically by the KKR
band-structure calculation.

School of Science, Osaka University
Lawrence Berkely Laboratory, U.S .A .

109

RIKEN Accel. Prog. Rep. 29 (1996)

Effect of Ligand Distortion on the Hyperfine Magnetic Field of
61Ni2+ Ions in the Spinel Chromites t
Y. Kobayashi, T. Okada, Y. Noro,* J. Nakamura, and H. Kitazawa**
We have applied 61 Ni Mossbauer spectroscopy to thespinel-type chromites Mo.g61 Nio.1 Cr204 (M = Mn,
Co, Cu, and Zn), in which Ni 2+ ions were substituted
for a part of M 2 + at the A-sites. 1,2) These Mossbauer
spectra measured at 5 K presented symmetric and resolved hyperfine structures, typically observed in thecases of a pure hyperfine magnetic interactions. The
derived IHhfl of Ni 2+ ions at the A-sites are 800, 540,
510, and 390 kOe for Cu-, Co-, Zn-, and Mn-chromite,
respectively. We summarize our present results of IHhfl
against the cia ratio as the ligand distortion in Fig. 1
together with the previous results of NiCr2043) andthe system of NiFexCr2_x04.4) It is indicated that the
IHhfl of Ni 2+ at the A-sites depends linearly on the
Jahn-Teller distortion cia. We will discuss the mechanism and the origin of the large IH hf I in considerationof the relation between the electronic state of a Ni 2+
ion and the ligand distortion.

900

Cu
800

700

~

I

NIFe.c'2_..p.

Q)

0..><:

.~/

600

E

:!;

CO.
500

,.,0 15

Ni

400

o Mn

300
0.90

0.95

1.00

105

cia

Fig. 1. Ligand distortion c/ a dependence of the hyperfine
magnetic field of Ni 2 + ions at the A-sites of the spinels.
The magnitude of Hhf at a nucleus can be calculated by the sum of the Fermi contact term, the field
caused by the orbital angular momentum, and thedipole magnetic field. 5) The first term is estimated to
be around -270 kOe for Ni 2+ ions and the third to bevery smal1. 6) However, the observed IHhfl in this paper
are much larger than the values of the Fermi contact
term. So, the contribution of the orbital angular momentum is expected to be dominant in the total IHhfl
in this system.

Condensed from the article in Phys. Lett. A, 209 , 241 (1995)
Hitachi Multimedia Systems R&D Division
National Research Institute for Metals

110

The energy level of the ground state of dB ions at
cubic tetrahedral A-sites is a triply degenerate 3T 1u 'The degeneracy at the A-sites could be removed by ligand distortion arising from the Jahn-Teller effect. Theenergy level of the ground state of Ni 2+ ions should be
split into a singlet and a doublet. The ground state in
NiCr204 becomes a singlet due to the Jahn-Teller distortion of cl a > 1. It means that this L; = 0 state has
no effective orbital angular momentum. However, anappreciable orbital angular momentum should be induced as a second-order perturbation by the exchangeinteraction and the spin-orbit interaction in spite ofa singlet state. In contrast, the ground state in Cuchromite (cia < 1) is doubly degenerate and corresponds to L; = ±1 , so that the orbital angular momentum arises from the first-order perturbation. The
difference between the energy levels in both cases canbe reflected in the magnitude of Hh f through the induced orbital angular momentum.
In the effects of ligand distortion, cia < 1 stabilizes
the L; = ±1 states and splits the L; = 0 far above theL; = ±1. The spin-orbit interaction connects the L; =±1 states and the L; = 0 state by the selection rule. As
a result, the Jahn-Teller interaction and the spin-orbit
interaction cooperate to enhance the orbital angularmomentum. This situation is realized only under thecondition cia < 1 (CUCr204 and NiCr1.5Feo.504). For
cl a > 1, the ligand distortion results in an opposite
effect for inducing orbital angular momentum; a larger
distortion results in a smaller IHhfl.
I t is believed that the symmetry of the ligands of
Ni 2+ ions is not cubic in Co- and Zn-chromites, so that
IHhfl must be smaller than that of NiCr1.5Feo.504 butlarger than that of NiCr204' The observed IHhfl ofMno.g61Nio.1Cr204 with cia = 1 is discussed in another report. 7)
References
1) T. Okada et al.:

RIKEN Accel. Prog. Rep. , 28, 80(1995) .
2) T. Okada et al.: Phys. Lett. A, 209, 241 (1995).
3) H. Sekizawa et al.: l. de Physique, 32, Cl-326 (1971).
4) J. C. Love and F. E. Obenshain: AlP Conf. Proc. , 18 ,
513 (1973).
5) E. Fermi and E. Segre: Z . Physik, 8 , 729 (1933).
6) A. Okiji and J. Kanamori: l. Phys. Soc. lpn., 19, 908(1964).
7) T. Okada et al.: This report, p. 112.

RIKEN Accel. Prog. Rep. 29 (1996)

In-Beam Mossbauer Study on Pure Iron
Using 56Fe(d, p) 57 Fe Reaction
Y. Yoshida, Y. Kobayashi, J. Nakamura, F. Ambe, E. Vagi,
R. Sielemann,* T. Grund,** and A. Seeger**
Iron is one of the largest industrial productions andmost widely used among all other metals in the world.
However, the nature of point defects in pure iron isstill a large open question. There have been controversial interpretations on the recovery stages for vacancies and self-interstitials. In order to study the natureof point defects in pure iron from an atomistic pointof view, we use an in-beam Mossbauer technique,l-4)
which appears to provide information not only on the
structure and the stability of point defects , but also on
their jump processes.
Although it is rather difficult to detect the point
defects in pure iron because of the very low concentration of defects , two Mossbauer experiments havebeen performed so far: A conventional source experiment on 57 Co doped iron, which was irradiated byneutrons and electrons at low temperatures,5) showed
recovery stages after annealing in the total area intensity, the hyperfine splitting and the line width as well.
Furthermore, in an in- beam Mossbauer experiment using Coulomb-excitation and recoil-implantation 6 ) twostages were found around 300 and 650 K in the same
Mossbauer parameters as in the source experiment.
In an in-beam Mossbauer experiment using
56Fe(d, p) 57 Fe reaction, a pulsed deuteron beam is .
used to produce 57Fe nucleus in the target of pure iron.
The Mossbauer probe of 57Fe is excited to the nuclear
level of 14.4 keY and simultaneously ejected from lattice sites with the average recoil energy of several hundreds keY. The recoils of 57Fe stop on different latticesites in the specimen within the time of a few picoseconds. Subsequently the emitted l'-rays are measured using a parallel-plate-avalanche counter (PPAC)
between deuteron pulses. Accordingly, this in-beamtechnique provides a possibility to study both the finallattice sites of 57Fe atoms "internally" implanted inpure iron and their jump processes at elevated temperatures. In order to determine the jump vectors of implanted 57Fe atoms on different sites, one has to measure the angular dependence of Mossbauer spectrum
at different crystal orientations. Since the active area
irradiated by deuterons is rather small (5 x 10 mm) ,the measuring geometry in the present method is much

1600

t3

c::
~

o

U

1400
1200

1000

-8

-6

-4

-2

0

2

4

6

8

velocity [mmls]
Fig. 1. Mossbauer spectrum of 57Fe in pure iron after
56Fe(d, p) 57 Fe reaction measured at 35 K.

superior than that of the in-beam Mossbauer techniqueusing Coulomb-excitation and recoil-implantation.6 )The energy and the intensity of deuteron beam fromthe AVF cyclotron were 8 MeV and 200 nA, respectively. We measured a polycrystal iron and also a single crystal at different temperatures from 35 to 300 K.
Figure 1 shows the Mossbauer spectrum of a polycrystal iron at 35 K. No satellite component due to defects
can be seen in all spectra. However, the line width andthe hyperfine splitting at 35 K are slightly different
from the values obtained in an absorber experiment1)
on pure Fe. In addition, these Mossbauer parameters
show unusual t emperature dependence at around 300
K, which may originate from a jump process of defects.
References
1) Y. Yoshida, M. Menningen, B. Keck, G. Vogl, G. Weyer,
and K. Schroder: Phys. Rev. Lett. , 61, 195 (1988).
2) Y. Yoshida: Hyperfine Interact, 47, 95 (1989).
3) R. Sielemann and Y. Yoshida: ibid. , 68, 119 (1991).
4) B. Keck, R. Sielemann, and Y. Yoshida: Phy. Rev. Lett.,
71 , 4178 (1993).
5) Y. Yoshida, S. Nasu, and F. E. Fujita: Proc. Yamada
Conf. 5th on Point Defects and Defects Interactions in
Metals and Alloys, eds. J. Takamura, M. Doyama andM. Kiritani, p. 199 (1982).
6) Y. Yoshida, D. Thppinger, G. VogI, B. Keck, and R.
Sielemann: HMI-B. Annual Rep., 490 , 112 (1990).
7) R. S. Preston, S. S. Hanna, and J. Heberle: Phys. Rev.,
128, 2207 (1962).

Hahn-Meitner-Institute , Berlin, Germany
Max-Planck-Institute fUr Metalforschung & Max-PlanckInstitute fUr Physik, Stuttgart, Germany

111

RIKEN Accel. Prog. Rep. 29 (1996)

61 Ni Mossbauer Spectroscopy on Cubic Spinel Chromites

T. Okada, Y. Noro,* Y. Kobayashi, J. Nakamura, H. Kitazawa,** and F. Ambe
In pervious papers,1 ,2) we reported that, in 61 Ni
Mossbauer spectroscopy, the hyperfine magnetic field
H hf of 61 Ni ions in the A sites of spinel chromite
CUo.gNio.1 Cr204 was found to be 800 kOe, which is thelargest ever reported for 61 Ni. The magnitude of Hhf
of 61 Ni 2+ ions in the A sites of various spinel chromites
has been shown to be linearly dependent on the ligand
distortion of the crystal. Calculation of the orbital angular momentum caused by the ligand distortion accounts for the above characteristics. 3) It means thatthe orbital angular momentum is the main origin of
the large H hf .
In this report, 61 Ni Mossbauer measurementsof three cubic spinel chromites MO.g61 Ni o.1Cr204(M=Mn, Co, and Zn) are made to clarify in detail theH hf of 61 Ni 2+ ions on the basis of the orbital angularmomentum.
The single line source of 61 Cu (---+ 61 Ni) was produced in the RIKEN AVF cyclotron. Powdered specimens were prepared by the conventional ceramic sintering method. The source and absorber were kept at
the same temperature, 5 K, in a liquid helium cryostat. Experimental procedure was reported in detailin Ref. 2.
Mossbauer
spectraof
CoO.g61 Nio.1 Cr204,
ZnO.961 Nio.1 Cr204 and MnO.g61 Ni o.1Cr204 taken at 5
K are shown in Fig. 1. Each spectrum consists ofbroad and spread lines. Twelve straight solid lines
at the bottom of the figure are the calculated positions and intensities of the absorption peaks causedby Hhf. The values of Hhf amount to 390 kOe
for Mno.g61Nio.1Cr204, 540 kOe for COo.961Nio.1Cr204
and 510 kOe for ZnO.g61 Nio.1 Cr204, respectively. The
values of 540 and 510 kOe are expected by calculation of the orbital angular momentum under the cubic
symmetry (cia = 1) when the direction of the orbital
angular momentum lies in the c plane. The value of390 kOe for MnO.g61 Nio.1 Cr204 is considerably smaller

Hitachi Multimedia Systems R&D Division
National Research Institute for Metals

112

99

co

I(, II. 011 .d
-10

0

5K
10

20

Velocity (mm/s)

Fig. 1. 61 Ni Mossbauer spectra of cubic spinel chromites
at 5 K. Co: COo.9Nio.1 Cr204, Zn: Zno.9Nio.1 Cr 204, and
Mn: Mno.9Nio.1 Cr204.

than the others. The specimen MnCr204 has a ferrimagnetic spiral structure below 20 K. The spin direction for MnCr204 rises from the c plane toward thec axis. 4) Then, the orbital angular momentum which
has the maximum value in the c plane is deduced byraising the spin from the c plane. Therefore, H hf for
Mno.gNio.1Cr204 is smaller than the others. This confirms that the orbital angular momentum is the main
origin of the large H hf .
References
1) T. Okada et al.: RIKEN Accel. Prog. Rep., 28, 80(1995).
2) T. Okada et al.: Phys. Lett. A, 209, 241 (1995).
3) Y. Kobayashi et al.: This report, p. 110.
4) J. M. Hastings and L. M. Corliss: Phys. Rev., 126, 556(1962).

RIKEN Accel. Prog. Rep. 29 (1996)

1. Watanabe, S. Nakajima,* and K. Nagamine

The Tl-system cuprate is one of the hole-doped highT c cuprates which show the highest transition temperature, Te. The hole density of TIBa2 Y1-xCaxCU20y
which is the so-called 1212 system and one of the TIfamilies can be changed by the substitution of Ca 2+
for y3+. The crystal structure is inserted in Fig. 1.
The system shows the insulating behavior at x = O.
The electric conductivity of the system increases withincreasing x. The SC appears x > 0.5. 1) Te grows
up suddenly and shows a maximum (Te ~ 100 K)
around x = 0.6. By the analogy with other hole doped
cuprates, some magnetically ordered states of Cu spinsare expected to appear near x = 0; however, there has
been no study in the insulator region near x = O. To
investigate the magnetic state of the system, the ,uSR
measurement is a powerful technic because the injectedmuon (S = 1/2) interacts with electrons and nuclei inthe crystal only through magnetic interactions. In thispaper, we report the first observation of the AF ordered state of the Cu sipns in the TI-1212 system by
the ,uSR measurement.

.1

885:

TL BRYCUO

50.000

. 075

E
c

<D

~ . os

r--

N

-'
;.025

u

O.3850nm- .0 25-. os 0

4

6
TIME (mlcrosecl

10

12

.Cu

00

Fig. 1. Time evolution of the positive surface muon spin
asymmetry taken under the zero field at 49 K. The crystal structure of the TI-1212 system is also shown.

The ,uSR measurement has been done at RIKENRAL Muon Facility, which has started to work fromthe beginning of 1995 at Rutherford-Appleton Lab. inUK,2) under the zero field condition by using the surface muon beam with a momentum of 27 Me V / c.
The time evolution of the muon spin asymmetry for
x = a at 49 K is shown in Fig. 1. Two precession components are observed. The existence of the precessionof asymmetry means that a unique internal magnetic
field which is due to the magnetic ordering of the system exists at each muon site. Thus, this finding in the
Department of Chemistry, Tohoku University

'I

'I
0

0.3

'+ ~ 0 o"o9loo~'+ + + 0. 0

-

T

+~
~

NO.2 t-

-

o

:r:
~

~0
0

0.1 I-:-o Tl Ba2Y(u2-o,.

OL-~LW~·~I~~~~, I __~~~

1

10

T(KI

100

1000

Fig. 2. Temperature dependence of the frequency of theslow precession component in the muon spin asymmetryof TIBa2 Y l - x Cax Cu 20y. The open circles are for x = 0
and the closed circles are for x = 0.5 .

1212

O. 0 01 PO L Y ( I v 5 2 ) RS Y

zero field measurement shows clearly the existence ofthe magnetically ordered state of the Cu-spins. Because there are two components of the precession frequency, there are at least two sites at which the injected muons stop in the crystal. The saturated internal field at each muon site is about 170 and 23 Gauss,
respectively.

Figure 2 shows the temperature dependence of thefrequency of the slow precession component for x = a(open circles) . The frequency is constant below 100 K
and decreases with increasing temperature above 100
K . The precession is still observed at room temperature
indicating the existence of the magnetic ordered state.
The estimated magnetic transition temperature, TN ,is about 400 K.
Similar measurements have been done on this system changing x up to 0.5 by 0.1 step. In each sample
similar two precession components were observed. The
temperature dependence of the frequency of slow precession component for x = 0.5 is shown in Fig. 2 (closed
circles). No difference in the saturated internal fields at
the muon sites and no difference in TN'S were observed
among all samples, indicating that there is no change
in the electronic state of the CU-02 plane even thoughy3+ is substituted by Ca2+ up to 50%, which operation is expected to induce holes in the CU-02 plane.
The more detailed analysis and the measurement III
the SC state are going on now.
References
1) S. Nakajima et al.: Physica, C182, 89 (1991).
2) K. Nagamine et al.: Hyperfine Interact., 87, 1091
(1994).

113

RIKEN Accel. Prog. Rep. 29 (1996)

J.t±SR Measurement of La2-x(Ba,Sr)xCu04 around x

0.12

1. Watanabe, K. Kumagai, * and K. NagamineThehigh-Tc
superconductivity(SC)in
La2-xBaxCu04 and La2-xSrxCu04 disappears withina narrow range of the dopant concentration aroundx = 0.12.1) When the concentration of doped holes inthe system is changed by substituting Li for Cu2) orby substituting Th for La,3) the value of x at which
the SC is most suppressed is shifted, showing that the
suppression of the SC strongly correlates with the holeconcentration in the system.
In the La-Ba system, the transition from the orthorombic (LTO) to the tetragonal (LTT) structure
occurs below 60 K for x = 0.125 4) and this structural transition affects transportation phenomena of
the system. S ) The LTO-LTT transition has not been
observed in the La-Sr system; when La is substituted
by Nd (La-Nd-Sr system); however, the LTO-LTT
transition occurs and the SC is suppressed. 6 )From the zero-field J.L+SR measurement using thepulsed surface muon beam, an antiferromagnetic (AF)order of Cu-spins was observed in the La-Sr and the
La-Ba systems around x = 0.127 ) at low temperatures.
Figure 1 shows the x-dependence of the magnetic transition temperature, TN. In both systems, T N shows its
maximum when the SC is most suppressed, showingthat the AF ordered state of Cu-spins competes with
the SC state. 7 ) Because of no big difference in the magnetically ordered states, a similar ordered state of Cuspins to the one observed in the La-Ba system appears
in the La-Sr system.
Recently, it is reported from the neutron diffraction
measurement on the La-Nd-Sr system that the SC is
suppressed by the stripe structure of the spin density wave (SDW) and the charge density wave (CDW)

which is stabilized by the LTO-LTT transition. 8 )It has been believed that the magnetic ordered stateof the Cu-spins suppresses the SC; however it is stillin controversy why the magnetic ordered state can bestabilized within the narrow range ofx = 0.12. To clarify the driving origin of the magnetic ordered state,a J.L-SR experiment was performed at the RIKENRAL Muon Facility 9) at which the worldwide strongest
pulsed J.L - beam is available.
Figure 2 shows the time evolution of the J.L- spin
asymmetry of the La-Sr system in zero field for x =0.115 at 1.5 K. The time spectrum is well fitted by the
exponential type relaxation function , indicating thatfluctuations of the magnetic field which are inducedby the magnetically ordered state of Cu-spins, exist
at the oxygen site. 10 ) The temperature dependence ofthe zero field measurement is now in progress and it
is expected that more detailed information of the electronic state of CU02 plane will be obtained in the near
future .
. 05

73 0:

LRSRCUO

1. 50 00 . 001 POLY ( 2V5I ) RSY

.04
.03
'-

"

.02

V>

cr:

.01

0

u

-. 0 I- .02-. 0 25

0

2

3
TIME (mi c r o sec )Q' 30• La-Sf

~

'-'"

~

Fig. 2. Time evolution of the negative muon spin asymmetry in the La-Sr system for x = 0.115 at 1.5 K. The
AF ordered state appears in the system at this temperature.

it

20

t+tt r

10

0
0.08

0.10

~

0.12

0.14

X
Fig. 1. x-dependence of TN of t he La-Ba and the La-Sr
system around x = 0.12.
Department of Physics,
University

114

Faculty of Science, Hokkaido

References
1) K. Kumagai et al.: Physica C, 235-240, 1715 (1994) .
2) S. Shamoto et al.: Solid Stat e Commun. , 76 , 923 (1990).
3) Y . Maeno et al. : Phys . Rev. , B44, 7753 (1991).
4) J . D. Axe et al.: Phys. Rev. Lett., 62, 2751 (1989).
5) M . Sera et al.: Solid Stat e Commun., 69 , 851 (1989).
6) M. K. Crawford et al.: Phys. Rev. , B44, 7749 (1991) .
7) I. Watanabe et al.: Hyperfine Interact. , 86 , 603 (1994).
8) J . M . Thanquada et al.: Nature, 375, 561 (1995).
9) K. Nagamine et al.: Hyperfine Interact., 87, 1091
(1994).
10) R. S. Hayano et al.: Phys. Rev., B20, 850 (1979).

RIKEN Accel. Prog. Rep. 29 (1996)

J. Nakamura, 1. Watanabe, K. Asai, F. Ambe, and K. Nagamine
The NiAs-type intermetallic compound, Fe1.l5Sb,
was studied using pulsed 27 MeV /c J.L+ -beam under zero-field condition in the temperature range of
6 t'J 280 K at RIKEN-RAL Muon Facility.1)
According to early studies, magnetization, polarized neutron diffraction (PND) and 57Fe Mossbauer
effect measurements of Fe1.l4Sb , Fe atoms on the regular sites in NiAs-type crystal structure possess themagnetic moment of t'J0.9 J.LB , and their magnetic moments are ordered below 105 K with a triangular spinarrangement in the c-plane. 2 ,3) The temperature dependence of the hyperfine magnetic field , HhJ , at theregular site 57Fe reveals the Neel temperatures, TN ,of 200 and 140 K at x = 0.15 and 0.25 of Fel+xSb,
respectively.4) There is no anomaly around TN in thetemperature dependence of the magnetization, but abroad cusp is observed at t'J10 K. It is considered thata large magnetic susceptibility of the interstitial site
Fe atoms, which are ordered below the cusp temperature, buries the anomaly at TN. Because of no magnetic Bragg peaks in PND pattern for the interstitial
Fe atoms, their magnetic moments are considered tobe frozen into a spin-glass state, but the detailed magnetic property is not clarified yet. The purpose of thepresent study is to obtain information on the magnetic
properties of the regular and interstitial Fe atoms bymeans of J.L + SR.
A polycrystalline sample of Fe1.l5Sb was preparedby melting appropriate weight of the powdered raw
materials in an evacuated quartz tube. The ingot was
powdered and submitted to the measurements. The
concentration was confirmed to be x = 0.15 from thelattice constants.
Figure l(a) shows the temperature dependence of
the initial asymmetry of the muon-spin polarization
assuming a single component of the exponential decay. The initial asymmetry drastically decreases withdecreasing temperature around 200 K , showing that amagnetically ordered state of the regular site Fe atoms
sets in below this temperature (TN t'J 200 K). On further cooling, the initial asymmetry recovers up to 1/3of the full asymmetry, indicating the appearance of astatic ramdom field. 5) This "1/3-tail" decreases gradually below 50 K because of dynamical spin fluctuations of Fe spins. The temperature dependence of thedepolarization rate ). is shown in Fig. 1 (b). That of ).
possesses a divergence around 140 K, which means avery large magnetic fluctuation of the regular site Fe
atoms below TN. Furthermore, the value of ). increases
with decreasing temperature below 50 K according to
the increase of the susceptibility, which shows the cusp
at t'JI0 K.

0.2

(a)

DO

S
C1I

E
E

0.1

i:i'

o

<{

o

0

0

0

0

°cP

0.0
0.4

300

(b)
0.3

3

0.2

~!--..

0.1

-+--0

0

10

0

100

t

•

~

.f

r-.

U")

....

0

0.0
1

1

2

0

.-<

~
0

200

'"....
off0100

Temperature (K)Fig. 1. The temperature dependence of the initial asymmetry (a) and the depolarization rate A (b). The hyperfine magnetic field Hhf at 57Fe derived from theMossbauer spectroscopy is also shown in (b) with solid
circle.

The present result of J.L+SR suggests gradualslowing-down of the magnetic fluctuation of the interstitial site Fe atoms below 50 K. The result is consistent with that of the previous Mossbauer study, inwhich HhJ at 57Fe at the interstitial sites appears gradually from a relatively higher temperature than thecusp temperature [see the solid circle in Fig. l(b)].4)
In 57Fe Mossbauer spectra, it is difficult to separate
the component of interstitial site Fe atoms from thatof the regular site Fe and to distinguish dynamical effects from the static distribution of HhJ . The present
result shows that the pulsed J.L + SR method is usefulfor the compound having plural kinds of magnetic moments with different dynamical fluctuations.
In order to clarify the magnetic properties below 50
K, experiments at much lower temperatures (below 6K) and those in a longitudinal magnetic field are proposed to obtain further information on the fluctuationsof Fe-spins.
References
1) K. Nagamine et al.: Hyperfine Interact., 87, 1091 (1994).
2) K . Yamaguchi et al.: l . Phys. Soc. lpn., 33, 1292
(1972).
3) T. Yashiro et al.: ibid. , 34, 58 (1973).
4) J. Nakamura et al.: Nuovo Cimento D, in press.
5) R. S. Hayano ~t al.: Phys. Rev. , B20, 850 (1979).

115

RIKEN Accel. Prog. Rep. 29 (1996)

Quantum Diffusion of Positive Muon in Pure Tantalum
R. Kadono, 1. Watanabe, and K. Nagamine
Quantum diffusion is an interesting phenomenon in
crystalline solids where light interstitial particles like
protons and muons migrate by tunneling under the
potential barrier between adjacent sites. Because of
the light mass the tunneling amplitude of implanted
muons is expected to be greatly enhanced and there bydominate their diffusion property. The characteristicof the quantum tunneling diffusion emerges as a hopping rate proportional to the negative power of temperature i.e., v ex: T-a., where the value of a depends
on the property of a dissipative bath coupled to thetunneling particle. Such a power-law has been clearlyobserved both in metals with a ~ 0.6 1 ) and in ionic
crystals with a ~ 3 rv 7. 2- 6 )One of the most interesting aspects of the diffusion in metals is the idea that the cloud of normal
conduction electrons around a charged particle (e.g.,positive muon) cannot follow the motion of the particle adiabatically, as a consequence of the orthogonality catastrophe originating from divergent infraredcouplings to the electrons. This non-adiabatic behavior of particle-electron polaronic state leads to a muchsmaller power (i.e., 0 < a < 1)7,8) as seen for the muon
diffusion in metals compared with that in insulators
where particle-phonon interaction is explicit. Moreover, it is theoretically predicted that this particleelectron coupling can be directly tested by looking
into the effect of superconductivity on muon diffusion:
The superconducting energy gap introduces a cut-off
to the infrared couplings and thereby the adiabaticity
of particle-electron polaronic state must be restored. 7 )The first step for testing the above prediction is tolook for a suitable system; there are several candidates of simple metals showing superconductivity andsufficiently large nuclear moments (which is necessary
to observe the motional effects by j1SR), including V,
Nb, Ta, In, and AI. Recently we have measured themuon hopping rate in pure Ta (99.997%) by the ARGUS spectrometer at the newly completed RIKENRAL Muon Facility and obtained a very promising result. Namely, unlike in other bcc metals, the hopping
rate seems to be relatively slow « 106 S-1) and virtually not affected by the residual impurities during
the muon lifetime (=2.2 j1s). This is further evidenced
by the temperature dependence of the hopping rate

116

shown in Fig. 1, where the hopping rate increases withdecreasing temperature below about 30 K (a rv 2 for
15- 25 K then a rv 0.2 for 5- 15 K), showing turnovernear 4 K and decreases with decreasing temperature.

.4
(j)

.35
~r---.

. 3

-

I

1.

25

Q)

.2

-0

a::

.15

Q")

C
0...
0...

~

. 1

.07

To (4N7)
I

I

I

I

I

I

2

3

4 5

7

9

20

30

50

70

Temperature (K)Fig. 1. Temperature dependence of muon hopping rate
in pure Ta (99.997%). The T- 2 dependence is due tothe damping of tunneling by muon-phonon interaction
whereas T- O.2 is due to the strong electronic damping.
The T -dependence below 4 K is yet to be elucidated incomparison with the data in normal state Ta.

This result indicates that we are going to have an
opportunity for the first time in the past two decades
to study the effect of superconductivity on quantum
diffusion in an intrinsic system.
References
1) See, for example, G. M. Luke et al.: Phys. R ev., B43,
3284 (1991), and references therein.
2) R. F. Kieft et al.: Phys. Rev. Lett. , 62, 792 (1989).
3) R. Kadono et al.: ibid., 64 , 665 (1990).
4) J. W. Schneider et al.: ibid., 68, 3196 (1992) .
5) R. Kadono et al.: Phys. Rev., B50, 1999 (1994).
6) V. Storchak et al.: Phys. Rev. Lett., 72, 3056 (1994) .
7) J. Kondo: Physica, 125B, 279 (1984): ibid., 126B, 377(1984): Hyperfine Interact., 31 , 117 (1986).
8) K. Yamada: Prog. Theor. Phys. , 72 , 195 (1984); K.
Yamada et al.: ibid., 73, 1342 (1985).

RIKEN Accel. Prog. Rep. 29 (1996)

Spin Dynamics of JLAI Pseudo-Acceptor Centers
in Si Probed by JL-SR
R. Kadono, F. L. Pratt, 1. Watanabe, and K. Nagamine
The negative muon (f.l-) has a unique feature that
it is captured by an atom with a charge number Z
upon implantation to form a "muonic atom" with areduced charge number Z -1. This is due to the effective shielding of the nuclear charge by f.l- which has
about 200 times shorter Bohr radius compared withthat of a Is electron. When the initial f.l- is spinpolarized, it partially preserves the polarization duringatomic transitions between muonic orbits, maintaining
about 1/6 of the initial polarization at the muonic Is
state (when the nuclear spin is zero) to form a polarized "pseudo-nucleus (Z - 1)". The atomic process including the Auger electron emission is complete
within 10- 9 s which is much shorter than the time scale
probed by the f.lSR technique. Thus, the polarizedmuonic atom can be applied to the study of condensed
matter in a similar fashion as positive muons, despitesome technical difficulties that it has shorter lifetime
for the larger atomic charge number Z with a small
electron decay asymmetry « (1/3) x (1/6) rv 5%),and that the technique is virtually limited to thosewith no nuclear spins. For example, f.l-O probe has
been used to study the high-Tc superconductors andtheir parents compounds. 1 )It is known that the electron paramagnetic resonance (EPR) signal associated with acceptor centers
is hardly observed in elemental semiconductors due tofast electron spin relaxation,2) which has been the serious obstacle to the study of electronic structure ofactive centers. The implanted negative muon forms aspin-polarized acceptor center and thereby the f.l-SR
may serve as a complementary technique to provide microscopic information. Recently, some results of f.l-SR
study in crystalline silicon were reported,3,4) although
there remains some disagreement with each other. In
this short note we report our preliminary results off.l-SR study in crystalline silicon in comparison withthose by other groups.
The experiment was conducted at the port-2 channel of the newly completed RIKEN-RAL Muon Facility in the Rutherford Appleton Laboratory. A negative muon beam with a momentum of 50 MeV / c was
implanted into the sample consisting of 10 intrinsic
c-Si wafers ([111], resistivity -::: 2.2 kf2cm, total rv3
mm thick) and time-differential TF-f.lSR spectra wereobtained by the ARGUS spectrometer. 5) The appliedmagnetic field was 4.0 mT, which is considerably lower
than those reported in Refs. 3 and 4 (see below). The
long-lived background rate was such that the electrons from f.l - Si muonic atoms (lifetime ",,0.8 f.ls) wereclearly observed over 6 f.lS range.

Figure 1 shows the observed electron decay asymmetry and spin relaxation rate of f.l-Si (=J.LAI) versus
temperature. The asymmetry decreases as temperature is lowered below 40 K, disappearing almost completely at 10 K. This result is qualitatively in good
agreement with Ref. 3. On the other hand, the reduction of asymmetry is in accordance with the increaseof spin relaxation rate, which is also in line with theresult reported in Ref. 4. The change of asymmetry observed at 4.0 (this work) and 40 mT3) .is absent at 80mT4) and thereby suggesting that the hyperfine fieldfrom the electron shell at the J.LAI core may be 101.5
mT. The relatively slow relaxation observed below 40
K may be due to the spin-exchange interaction withquasi-localized holes near J.LAI acceptor centers. Moredetailed experiment is in progress.

>- 0.020:::f-

w 0 .01
::2
::2

&;

-- ---- -- ---- - ----- ---- -

0

<{

a)

-0.01 ~

1.5b).---....
I

UJ

3

t

N

f-

:::: 0 .5+ cp
o r ---- - - -- ---- --- -- -- - ~- 0 . 2 5 L.I.-_--'----'-~L.._1....J'_'_'_'_____'_____'___'

9

20 304 06080

200 3 00

TE MPERATRURE (K)Fig. 1. Temperature dependence of a) J.L-e decay asymmetry and b) spin relaxation rate for the ,.. Al acceptor
centers in c-Si.

References
1) N. Nishida: Hyperfine Interact., 79, 823 (1993).
2) See, for example, G. W. Ludwig, and H. H. Woodbury:
Electron Spin Resonance in Semiconductors, Academic
Press , New York (1962).
3) M. Koch et al.: Hyperfine Interact., 65, 1039 (1990).
4) T. N. Mamedov et al.: ibid. , 86, 717 (1994).
5) R. Kadono et al.: This report, p. 196.

117

RIKEN Accel. Prog. Rep. 29 (1996)

ILSR Studies on Magnetic Correlations and Spin Dynamics inKondo Semimetal CeNiSn
S. Flaschin, A. Kratzer, G. M. Kalvius , R. Kadono, 1. Watanabe , and K. Nagamine
The system CeTSn, where T stands for a d transition
element like Ni (3d), Pd (4d) or Pt (5d) , has attracted
considerable interest within the field of highly correlated electron systems. We study the series CeTSn
and related materials with J,LSR to gain information on
the development of magnetic correlations and on thespin dynamical behavior at very low temperatures.
The most interesting compound within this series
is CeNiSn. It led to the definition of a "new" classof materials termed "Kondo semiconduct ors" 1) since
it exhibits Kondo lattice behavior at more elevatedtemperatures, yet possesses in addition a very narrowgap (~lK) in the density of states at the Fermi surface. Neutron diffraction shows the gap to be open
only in certain directions of reciprocal space2 ) and recent heat capacity and resistivity data established basically metallic behavior at very low temperatures. 3)
Hence the name "Kondo-semimetal" appears more
appropriate.
J,LSR studies showed that magnetic correlations exist
at temperatures well below the gap formation.4 ,5) The
muon spin relaxation rate ). first rises with decreasing
temperature in a fashion typical for the relaxation behavior in a paramagnet near the magnetic transition
temperature but then saturates at temperatures below~ 100 mK. From longitudinal field decoupling data it isapparent that the electronic spin correlations responsible for the muon depolarization are of dynamic natureeven at lowest temperatures. The moment of the Ceions is very low due to the Kondo effect.
From transport measurements and bulk magnetic
studies 6 ) we know that magnetic correlations become
stronger by doping CeNiSn with Cu. This leads toa transition from a valence fluctuating semiconductor
via a heavy fermion state into an antiferromagnetic
Kondo state. The latter is reached in CeNi 1- x Cu x Sn
for a Cu-concentration of x 2: 0.13. The gap is closed
for a concentration of x 2: 0.10.
We want to learn how magnetic correlations arechanging in these samples. As a first step we did J,LSR
investigations on CeNio.9CuO.1Sn. Preliminary results
showed, as expected, the influence of the nuclear moments of Cu. Below 10 K a change in the relaxation
behavior could be detected. There were strong hints
that for T < 4 K a second fast damping signal appears.
Our experiment at the RIKEN beamline at RAL
should give more insight into the relaxation behavior.
We did zero field and longitudinal field experiments
in a temperature range from 1. 7 K to 10 K using the
VARIOX cryostat.
From the decoupling data in low longitudinal fields

118

0. 23

,.---,~~~~~~~-,

0. 22

~

0 , 21

~

0.2

:

O. 19

1 ---·r,.,..,":'''' ~'~UIlIIdil~ 0. 18~0 .11

8 0 . 16
O. 15 '------.J---'--'-----'----'----'----L--l----'-:....-.J

0 . 23,.---.~~~~~~~~

0.22
;

0.21

:. 0.2: 0 . 19r~~~w~~~W

g 0 .18~ 0.17u

0.16
O. 15 '-------'----'-~---'--_'__-'---'---.J.----'-~

o

1

2

3

•

5

6

1

a

9

1

TIME l .lc rcsl!:c lFig. 1. Decoupling of the nuclear damping of Cu. Zerofield (a) and longitudinal field of 10 G (b) at 10 K areshown as an example.

(see Fig. 1) we could conclude that the Cu ions
are homogeneously distributed within the Ni matrix.
This conclusion could be drawn from comparison with
Monte-Carlo simulations.
Furthermore, the results showed that the former
data have to be reinterpreted as a change in signal shape instead of assuming an additional strongly
damped signal. From these data we concluded thata further change in spectral shape could be expected
at even lower temperatures. Since this temperature
range is not accessible at t he RIKEN beamline we
continued our experiment at the MUSR beamline using the dilution refrigerator. We found spin- glass likebehavior. 7 ,8) We assume t hat the Cu ions induce a moment at the Ce neighbors. This phenomenon was seen
before in so called "induced moment spin glasses" as
PrP 9) or ScTb. 10 ) Thus, we have high moments at
Ce statistically distributed in a Ce matrix with very
low moments. At the lowest reachable temperature(40 mK) the field distribution appears to be static incontrast to CeNiSn.
References
1) T . Takabatake et al.: Phys. R ev., B41 , 9607 (1990) .
2) T.E. Mason et al.: Phys. Rev. Lett. , 69, 490 (1992) .
3) G. Nakamoto et al.: Physica B , 206 & 207, 840 (1995) .
4) A. Kratzer et al.: Europhys. Lett., 19 (7), 649 (1992).
5) G. M. Kalvius et al. : Physica B, 206&207, 807 (1995).
6) T. Takabatake et al.: J. Magn. Magn . Mat. , 76&77 ,87 (1988).
7) Y. J. Uemura et al.: Phys. Rev., B39, 4729 (1989).
8) 1. A. Campbell et al. : Phys. Rev. Lett. , 72 , 1291 (1994).
9) S. K. Hasanain et al.: Phys . Rev. , B24, 5165 (1981).
10) H. Yoshizawa et al.: ibid., B27, 448 (1983).

RIKEN Accel. Prog. Rep. 29 (1996)

The Spin Dynamics of Polarons in Polyaniline Studied by IL-SR
F. L. Pratt, A. Monkman,* K. Ishida, 1. Watanabe, R. Kadono, and K. Nagamine
Cond ucting polymers such as polyaniline have beena source of considerable scientific and technological interest since the discovery of high metallic conductivity in doped polyacetylene and further discoveries ofinteresting electro-optical properties such as large optical nonlinearity and electroluminescence in various
conjugated polymer systems. Fundamental to the understanding of these conducting polymers are the nature and properties of their charge and spin excitations, which take the form of polarons and solitons.
The muon is a particularly sensitive probe of these excitations, as the muon implantation process itself generates an excitation whose dynamical properties canbe studied via the evolution of the muon spin polarisation. This was first demonstrated in polacetylene using J-L+SR1) and subsequent studies were reported fora range of conducting polymers. 2 ) We report here an
extension of these studies using the J-L-SR technique,which has been made possible following the recent completion of the RIKEN-RAL Pulsed Muon Facility at
the Rutherford Appleton Laboratory.
Measurements were made using negative muons witha momentum of 60 MeV Ic at RIKEN-RAL Port 2(J-LSR port). The polyaniline (emeraldine base) sample consisted of an array of seven pressed discs each2- 3 mm thick and 12 mm in diameter with 3 mm ofsilver before the sample acting as a degrader. The
muon spin rotation was first checked in weak transverse fields to measure the diamagnetic amplitude andthen the longitudinal relaxation was studied as a function of longitudinal field. Measurements were made at
10 and 300 K.
In contrast to positive muon implantation in undoped conducting polymers, where muonium is formed
initially, which then rapidly reacts with the polymer,
negative muon implantation leads to the formationof muonic atoms, where the nuclear charge becomesshielded by the muon to form an atom with effective
atomic number Z-I. Polyaniline consists mostly of carbon which will be converted to boron-like atoms by thisprocess. This leaves a spare electron in the form of apolaron which is free to diffuse away from the implantation site. The spin diffusion process can be monitoredby the relaxation of the muon spin and in particular
the longitudinal field dependence of the relaxation rate
provides important information about the spectral dimension of the diffusion process.

Figure 1 shows the measured relaxation rate as afunction of field. Very different behaviour can be seen
at high and low temperatures. At 10 K the power-law
field dependence indicates low- dimensional spin diffusion in a regime where interchain transport is relatively
slow. In contrast the weakness of the field dependence
at 300 K indicates fast interchain transport and 3D
spin diffusion.

1000

-;:;I

!

:;t.

...

10 K

!

OJ

III

! t

0::

c
0

........ 100
III
X
III

......

f

OJ

0::

N

I

:;t.

1000

.....OJ
III

0::

c

.....o
.....

300 K

III
X
III

......

~

100
10

100
1000
Magnetic Field (G)Fig. 1. j.1- longitudinal spin relaxation rate in Polyaniline(Emeraldine base) as a function of applied magnetic
field at 10 and 300 K.

J-L - SR is expected to be particularly useful in systems with slow nuclear capture i.e. with low atomic
number, as found in organics, and these initial results
demonstrate that J-L-SR in conducting polymers canprovide a valuable complementary technique to J-L+SR
and other magnetic probes.

References
1) K. Nagamine et al.: Phys. Rev. Lett., 53, 1763 (1984).
2) F. L. Pratt et al.: Synthetic Metals, 55, 677 (1993).

University of Durham, U.K.

119

RIKEN Accel. Prog. Rep. 29 (1996)

LF JLSR Studies on Reorientational Dynamics in Solid C 70
Using the ARGUS Spectrometer
R. M. Macrae, R. Kadono, F. L. Pratt, K. Tanigaki, * and K. Nagamine
Muon techniques have proved valuable in the studyof reorientational dynamics and electronic structure in
the pure fullerenes C 60 and C 70 , and in particular inel ucidating the motional differences between them produced by the presence or absence of 10 C atoms. 1 ,2)The dynamics of C 70 have been found to be rather
complex, and discussion of the microscopic mechanism
involved is by no means over.
When positive muons are implanted into fullerenes
two distinct hyperfine probes are generated. During
its deceleration process from MeV energies J.l+ picks
up an electron to form Mu, a light isotope of atomic
H. Inside the fullerene spheroid this atom is stable overthe muon's microsecond-scale lifetime, and has hyperfine parameters close to their vacuum values. On thefullerene exterior Mu reacts very rapidly to form a radical with a reduced hyperfine interaction anisotropic in
the molecular frame. The interaction of this anisotropy
with reorientational motional anisotropy as a functionof temperature is a "handle" on microscopic molecular
dynamics.
In C 70 there are five distinct sites for radicalforming chemical addition, labelled A to E from poleto equator. Studies by time-integral avoided levelcrossing J.lSR2 ) showed the presence of reorientational
anisotropy up to 370 K, proving muons a more sensitive probe of this anisotropy than neutrons or NMR.
The behaviour was modelled pseudostatically in termsof an effective axial anisotropy DII (T), and the energetics were considered within a simple thermodynamic
model involving four dynamical populations Xi undergoing different types of motion.
The present experiments use the technique of timeresolved LF J.lSR spectroscopy to extend these dynamical explorations. The decay asymmetry measured asa function of field shows a recovery pattern dependent
on the hyperfine tensor components. In particular, thehyperfine anisotropy is revealed in the very low fieldpart of the repolarisation pattern. (See Fig. 1.) The
yields and isotropic parameters of all 5 radical adducts
are known from transverse field experiments,3) whilezero-field measurements reveal that the most important radicals have similar static anisotropies. Henceit should be possible to reconstruct from the polarisation pattern as a function of T a set of thermodynamic
parameters comparable to that extracted from ALCJ.lSR.
Measurements were carried out using the ARGUS
spectrometer over 4 decades of field range from 0.5
G to ,3800 G. (See Fig. 2). Other techniques show
Fundamental Research Laboratories, NEC Corporation

120

Isotropic
Axial DII - 1 Ims (1)Dashed:DII - 3.5 Ims (2)DII - 7.5 Ims (3)DII - 10 Ims (4)Solid:

Anisotropic with
DD--S.53,Dyy--4.13.

10

20

15

Field/Gauss
Fig. 1. Calculated low-field repolarisation pattern forseveral effective anisotropies of a radical with isotropic
coupling AJ.£ = 275 MHz.
0.08

150 K

>.
I-.
.....,

0.08

Q)

S0.04
S
>.

00

-< 0.02

0.08

.•

230 K

.• .
•

."".

..••

<II
<II
<llfIl

,j"J

300 K

~

0.08
ID

.-..

•

ID
III

0.04

0.02
fIl

0.00

Fig. 2. ARGUS results for C 70 .

that at 150 K the reorientational motion is completely
frozen, while 230 K is just above the onset of uniaxial
reorientation and at 300 K (between the two macroscopic phase transitions) the unique axis is itself moving. However, the observed dependences are the opposite of what would be expected within the simple static
model. This indicates that the data contain extra dynamical information not available from time-integral
techniques, relating to incomplete averaging over theoccupied motional' modes on the J.lSR timescale. A
crude model in which the anisotropic hyperfine parameters have a gaussian width while the isotropic couplingis held constant suggests the hf anisotropy is staticallybroadened at low temperatures and narrows as motion
becomes more rapid.
References
1) E. Roduner et al.: Chern. Phys., 192, 231 (1995).
2) R. M. Macrae et al.: J. Phys. Chern., 98, 12133 (1994).
3) A. Lappas et al.: J. Chern. Soc., Chern. Commun.,
1994,2743.

RIKEN Accel. Prog. Rep. 29 (1996)

Single Event Effect in Power MOSFETs by
High-Energy Heavy Ion
S. Matsuda, T. Akutsu, T. Hada, J. Aoki, T. Hirose, H. Ohira, Y. Nagai,
T. Kohno, N. Inabe, M. Kase, A. Goto, and Y. Yano
Power MOSFETs (Metal- Oxide- Semiconductor
Field Effect Transistors) perform excellently as powerswitching devices. However, power MOSFETs havea possible catastrophic failure mode known as Single
Event Burnout (SEB) phenomenon which is causedby turn-on of the parasitic transistor with the electric charge generated by penetration of a fast heavy
ion. It is important to consider this phenomenon inapplication of electronic devices in space.
The detailed mechanism of SEB was observed experimentally by the EPICS (Energetic Particle Induced
Charge Spectroscopy) measurement system. 1 ,2) The
experimental results were also confirmed with the numerical simulation technique.
RIKEN Ring Cyclotron was used for the heavy ions
irradiation. The selected ions were Kr and Xe , andtheir characteristics are shown in Table 1. To avoid
contaminant ions, irradiation was made using a defocused beam without a scatterer such as an Au foil. The
incident beam was monitored by an SSD just adjacentto the sample device.

Ci)

1E-2

~
-..:....
co

• Xe
• Xe
• Xe
x Xe

w

~
W
I-

-<
a:::
w

1 E-3

0

0
15
30
45

0
0

0

'ggll~~I~~!~1 Kr 015°
0

Co.)

zw

~

a:::
a:::

0A

Kr 30°.. Kr 45

o

::::)

u

0

U
<=I

co
W

CI)

1E-4

o

100

200

300

Vos (V)

Fig. 1. SEB occurrence rate (2SK725).

r .... -.

~
300
w
~

I>

I"

1.· 1»1

~~.

~

... ~

I--'

.1

I

II

1

1

· 1··

k>

I
i

~"'"
~ 200 ~~I~H1fffftft-H"iftTttTi:J=b~1TH~ > k I>
Ii"~,<.
II·xe l Ip"h I ·· • rKr I~r1··<

i

(I)

I

0:::

Table 1. Characteristics of the ions used in this study.

a
u 100

·1

~~-rT

Ions

Energy
[MeV]
2184
3536

LET
[MeV /(mg/cm 2 )]
17.4
33.7

Range
[J.L m(Si)]
385
339

co

~

. I>.

·\1 >

o

0

15

30

45

!!
!

I·

I

o

I> ..

60

75

90

ANGLE OF INCIDENT BEAM(O )Fig. 2. SEB occurs vs. angle of incident beam.

The sample device for this study was a Fuji Electric Corps
Power MOSFET 2SK725. Its maximum
drain-source voltage rating (VDS) was 500 V. The highvoltage rating requires a relatively thick active layer(",40 J.tm of epi-Iayer). However, Kr and Xe havelength ranges larger than the thickness of the active
region.
Kuboyama et al. reported the experimental results
only about normally incident irradiation to the test
sample. 1 ,2) In our experiment, the angle of incident
heavy ion beam was changed by turning the target,
because the Power MOSFETs will receive the cosmic
rays coming from every direction of the universe.
Figure 1 shows the SEB occurrence rate for each angle (0°, 15°, 30°, and 45°) with respect to the incident
beam. This figure shows that as the angle becomeslarger, the applied voltage, at which the SEB occurs,
becomes larger. This figure also shows that the results of Xe and Kr are different. The reason for thedifferent results for Xe and Kr is the difference of the
LET (Linear Energy Transfer). To analyze each experimental result , we compared the applied voltages
when the SEB occurs at 1 time per 104 ions. Figure 2
shows the result of the comparison. In case ofaXeion, when the angle of incident beam is smaller than30°, the voltage at which the SEB occurs is smaller
than 100 V. If the Power MOSFET is used at the applied voltage smaller than 100 V for space application,
it will be affected by (1 - cos 30°) =: 0.134 portion of
total cosmic beams. This result is a most importantconcern for future work.
References
1) S. Kuboyama et al.: IEEE Trans. Nucl. Sci., NS-39,
1698 (1992).
2) S. Kuboyama et al.: ibid., NS-41, 2210 (1994).

121

RIKEN Accel. Prog. Rep. 29 (1996)

Heavy-Ion Irradiation Effects on the Single Crystal
La1.85SrO.15Cu04
M. Matsuda, G. Tatara, K. Katsumata, T. Kambara, Y. Awaya, T. Mitamura, M. Terasawa,
Y. Endoh,* K. Yamada,* and S. Hosoya**It has been reported that heavy ions irradiation onsuperconductors produces columnar defects which consist of continuous amorphous tracks. 1- 3 ) The columnar
defects are very efficient pinning centers for vortices.
The columnar defects not only enhance the critical current density J c, but they also cause new phases, suchas Bose-glass phase in the H-T phase diagram. 4,5)
We have studied heavy ions irradiation effects on the
superconducting properties of La1.85SrO.15Cu04 single
crystals. The crystals were grown by a traveling solvent ft.oating zone (TSFZ) method. The typical dimension of the sample was about 5(l) x 4(w) x O.l(t) mm 3 .
The unirradiated samples show a sharp superconducting transition Teat 37 K. The samples were irradiatedwith 3 x 1010 cm- 2 3.4 GeV Xe 3l + ions from the Ring
Cyclotron at room temperature. The ion beam wasaligned parallel to the c-axis. It is estimated that mostof the heavy-ion beams penetrate through the sample.
The magnetization and magnetic susceptibility were
measured by using a SQUID magnetometer.
We have observed remarkable irradiation effects on
the magnetization (M-H) curve as seen in Fig. 1 without degradation of T c. The critical current density

Jc is estimated from the maximum value of the magnetization. The presence of columnar defects increases
J c by a factor of 10 (5 K , 0.1 T) and 4 (25 K, 0.1 T).
Figure 2 shows preliminary results of the temperaturedependence of the irreversibility line (Hirr) where thehysteretic behavior appears in the M-H curve. Theline is to be identified with the melting line of the vortex lattice. The line is shifted to higher temperature
due to the columnar defects, which indicates that thevortex lattice becomes harder in the presence of strong
pinning. More detailed measurements of DC and AC
susceptibility are required to identify the new phase(Bose-glass phase) in La-Sr-Cu-O system.

La 1.85 SrO. 15 CU04 single crystal

2500

I 0 unlrradlated I

2000

~

•

1500

:I:£: 1000

1.85

Sr

0.15

CUO

200
3 x 1010 cm- 2 • • • • • •100osingle crystal

4

•• ~

.'.

T

4

•

0

0 0

.~1

~

••••

-200

10

15

20

25

30

35

40

Fig. 2. The irreversibility lines of the La1.85SrO_15Cu04
crystal before (open circles) and after (closed circles)
irradiation with 3 x 10 10 Xe 3 1+ /cm 2 (3.4 GeV).

~

-5000

0
H (Oe)

2

•

~
2

5000

References
10000

Fig. 1. M-H curves of the La1.85SrO_15Cu04 crystal before(open circles) and after (closed circles) irradiation with
3 x 10 10 Xe 3 1+ /cm 2 (3.4 GeV).

Department of Physics, Tohoku University
Institute of Inorganic Synthesis, Faculty of Engineering,
Yamanashi University

122

5~ •••• ••••• .._1..e, •• ··ee •..,...
4-100000c

H II c•unirradiated oooo~•
oe 8~ 000000000000000
00••.~ OOOO OO OOOO
~1 ooooooooooo ~~ R•
~ 00
oOg gggg g gg ggOOC'l. eJo~ -100H /I c-axis

Temperature (K)T = 15K••••••••.............

0

3Xl0'O cm-2

~~• ~

500
La

~

•

1) S. Behler et al.: Phys. Rev. Lett. , 72, 1750 (1994).
2) H. W. Zandbergen et al.: GSI Scientific Report, p. 213(1993) .
3) M. Terasawa et al.: Physica C, 235/240, 2805 (1994).
4) L. Krusin-Elbaum et al.: Phys. Rev. Lett., 72, 1914
(1994).
5) C. J. van der Beek et al.: ibid. , 74, 1214 (1995).

RI KEN Accel. Prog. Rep. 29 (1996)

Observation of Columnar Defects in 136Xe+31 Bombarded
Layered Materials
N. Nishida, H. Sakata, K. Satoh, S. Kaneko, H. Sawada, T. Kambara, and Y. Awaya
In copper-oxide high-T c superconductors, pinningeffects are weak due to the short coherence length(1"V30 A) and anisotropic nature of the superconductivity. It is essential to find how to increase pinningeffects for various applications of high-T c superconductors. In some matrials high energy heavy ionsgenerate columnar defects which are linear damage
tracts of 100 A diameter along the tracks of heavyions. These columnar defects have been found tobe effective to pin vortices of high-T c superconductors in high magnetic fields. Therefore, it is interesting and important to study how columnar defects are
generated and what the electronic states are aroundthem. In order to study influences of columnar defects on the surrounding electronic states and generation mechanisms of columnar defects, we have installed a newly designed target chamber at E5a beamline from RIKEN Ring Cyclotron and bombarded 3.4
GeV 136Xe+31 (26 MeV/nucleon) ions through single
f'V

crystals of several layered materials; Bi2Sr2CaCu20x,
1T-TaS2, 2H-NbSe2 and graphite (HOPG). 136Xe+31
ions of 3.4 Ge V have high enough energy to penetrate
our samples of about 0.1 mm thickness. They were observed by a transmission electron microscope (TEM)
and a scanning tunneling microscope (STM) at Tokyo
Institute of Technology. In Bi2Sr2CaCu20x, columnar
defects have been observed by TEM as shown in Fig.
la and lb. However, in 1T-TaS2 and highly oriented
pyrographite (HOPG) columnar defects have not been
observed as shown in Fig. 1c and Id. The reason why
these differences are brougt about is under consideration. At present the studies of Bi2Sr2CaCu20x are in
progress by using a scanning tunneling spectroscopic
microscope which can be operated at low temperature(2.2 K) and in high magnetic fields (14.5 T). We acknowledge professor N. Yamamoto (TIT) for taking
TEM photographs of our samples.

Bi 2212 296nm X 296nm

ab

1T-TaS , 900nm X900nmcd

Bi 2212 713nmX713 nm

HOPG 713nrnX713nrn

Fig. 1. Columnar defects observed by TEM in BbSr2CaCu20x (a), (b), in
IT-TaS2 (c), and in HOPG (d). The defects are seen as white spots in(a) and (b), but not in (c) and (d).

123

RIKEN Accel. Prog. Rep. 29 (1996)

Laser Spectroscopy of Atoms and Molecules in Liquid Helium
M. Nakamura, Q. Hui, J. L. Persson, Z. Jakubek, Y. Kasai , M.-P. Coquard, and M. Takami
We are currently studying the physical properties ofneutral atoms and molecules in liquid helium. Oneof the objectives of this work is to find the feasibilityof applying this technique to the on-line spectroscopic
study of unstable nuclei produced by RRC and to otherfundamental physics. For the first application, we are
studying the optical spectra of neutral atoms (impurity
particles) in liquid helium. 1 ,2) A neutral atom is known
to be trapped in a bubble-like cavity due to a strong
repulsive force between the impurity and surrounding
helium atoms. 3) The coupling of the cavities with thetrapped atoms induces a large shift and broadening of
the atomic spectra. Spectroscopic study of atomic ionsin liquid helium, which is more suitable for the studyof unstable nuclei, is also in progress.
For the second application, the measurement of electric dipole moment in a neutral heavy atom trapped insolid helium has been proposed. Our interest is to use
diatomic molecules containing heavy atoms to carryout a similar measurement. As a first step, we studied
electronic spectra of metal dimers and trimers in liquid helium. 4 ) A schematic diagram of the experimental set up and conditions were described in a previous
report. 5 )Neutral molecules are dispersed in Hell by laser ablation of solid metal samples immersed in Hell. A second YAG laser beam, with a few ms delay after theablation, dissociated the particles to disperse metal
molecules in Hell. A pulsed dye laser was used toexcite the molecules with a 50 ns- 10 ms delay timeafter dissociation. The emission from the molecules
was detected by a photomultiplier through a 25 cm
monochromator.
So far we studied electronic spectra of Ca2 , CU2 ,and Ag3 in liquid helium. The absorption and emission spectra of S-S transitions of Ca2 and CU2 showedvibrational structures. The CU2 emission spectrum isshown in Fig. 1 as an example. The emission has been
observed only from the lowest vibrational states, reflecting rapid relaxation of the dimer vibration in liquid helium. Vibrational frequencies and spacing of CU2
were slightly different from those in free space.
For the applications discussed above , high resolution measurements of atomic/molecular spectra are
indispensable.
Feasibility of optical pumping forhigh resolution radiofrequency spectroscopy among
the hyperfine and Zeeman sublevels has been demonstrated already.6) One important result in the present
work is the finding of rapid vibrational relaxation in

124

1-0

450

460

470

Wavelength

480

490

(nm)

liquid helium because this will allow optical pumping to produce non-thermal population distribution
among hyper fine and Zeeman sublevels in diatomic
molecules. For efficient production of non-thermal
population distribution, many cycles of optical absorption and emission are necessary. In molecules, thisis in general almost impossible because the optically
excited molecules has little chance to come back tothe same level due to the existence of many rotational/vibrational levels. In liquid helium, the rapid
vibrational relaxation and low temperature (typicallylower that 1.7 K) will allow a molecule repeated transitions between specific levels through absorption andemission of photons. The experimental confirmationof this technique is in progress.
In addition to stable diatomic molecules, we recently
succeeded in observing the emission from AgHe2 exciplex. When the D2 line of Ag atom was excited inliquid helium, a broad and red-shifted emission band
was observed in addition to the atomic D1 line. This
broad band has been assigned to the emission from theAgHe2 complex in Hell formed by the attractive potential between the P3/ 2 state of Ag and ground state
He atom. The assignment has been confirmed by simulation of the band profile based on an ab-initio AgHepair potential.
References
1) J. H. M. Beijersbergen et al.: Phys. Lett., A181, 393(1993).
2) Q. Hui et al.: Laser Chern. , 15 , 221 (1995).
3) H. Bauer et al.: Phys. Lett. , A146, 134 (1990).
4) J. L. Persson et al.: Phys. Rev. , A52, 2011 (1995).
5) M. Nakamura et al.: RIKEN Aeeel. Prog. Rep., 28, 77(1995) .
6) T. Kinoshita et al. : Phys. Rev. Lett. , B49, 3648 (1994).

RIKEN Accel. Prog. Rep. 29 (1996)

Behaviour of Xe Atoms in Xe-Implanted Iron
E. Yagi and M. Hacke*
It has been known that heavy inert gas atoms (Ar,Kr and Xe) implanted into metals at ambient temperature precipitate into micro-cluster, and that for highimplantation doses they are in a solid phase (solid inert gas bubbles) epitaxially aligned to matrices and ina high pressure state.
In previous channelling studies on Kr-implanted Al
crystals (an fcc crystal), we have demonstrated thatat the initial stage of implantation small complexes
such as Kr V4 and Kr V6 consisting of Kr atoms andimplantation-introduced Al vacancies (V) are formed,
and act as nucleation centres for the subsequent bubble
formation. 1-4)
For comparison of the behaviour of inert gas atoms
between fcc crystals and bcc crystals, we made channelling experiments on Xe-implanted Fe crystals (a bcc
crystal). Xe atoms were implanted into Fe single crystals at room temperature at an energy of 150 ke V up
to a dose of 1 x 10 16 /cm 2 . Rutherford backscatteringchannelling experiments were performed at room temperature with a He beam of 1.5 MeV for (100), (110)and (111) channels. The channelling angular profile
obtained for He ions backscattered by Xe atoms exhibits a simple shallow dip having the same angular
halfwidth as that of the channelling angular profile(channelling dip) for He ions backscattered by host Fe
atoms for each of these three channels. The relative
depth of the Xe dip with respect to the host Fe dip
was approximately 17%. As an example the result forthe (100) channel is shown in Fig. 1. This result indicates that approximately 17% of the Xe atoms arelocated at substitutional sites and the remaining 83%
are at random sites , i.e. in the form of bubbles. For the

• Fe
o Xe

.
.

1.0

-.()

o

~

w

;:

o

W
N

~ 05
2

a::
o
z

-4

-2

o

2

4

ANGLE(deg)Fig. 1. (100) channelling angular profiles obtained for a1 x 10 16 Xe/cm 2 implanted Fe specimen. The solid curve
and the broken curve are drawn only to guide the eye.

study of bubble nucleation, experiments on the specimens implanted with lower doses are being carried out.
References
1) E. Vagi: Phys. Stat. Sol., (a)104, K13 (1987).
2) E. Vagi: Nucl. Instrum. Methods Phys. Res., B39, 68(1989).
3) E. Vagi, 1. Hashimoto, and H. Yamaguchi: J. Nucl.
Mater., 169, 158 (1989).
4) E. Vagi: Phys. Rev. Lett., 67, 3804 (1991).

Present address: 1nstitut fur Schicht- und 1onen-Technick(1S12), Forschungszentrum Jiilich GmbH, Germany125

3. Radiochemistry and Nuclear Chemistry

RIKEN Accel. Prog. Rep. 29 (1996)

Differential Recoil Ranges of Reaction Products inthe eu + 14N, 40 Ar Nuclear Reactions
M. Furukawa, A. Shinohara, T. Muroyama, S. Kojima, K. Mukai, A. Yokoyama,
T. Saito, Y. Ohkubo, and F. Ambe
Recoil range distributions were measured for theheavy-ion 4 N and 40 Ar) nuclear reaction of natural
copper with a radiochemical technique. The experiments were performed at the E3b course of the RIKEN
Ring Cyclotron. The target was self-supporting 0.300.45 mgjcm 2 Cu metal foil and was set at the centerof a Lucite cylindrical chamber. In the interior of thechamber, the catcher foil stack consisting of 10 sheetsof Mylar films of 3.5- 23 J..Lm in thickness was put on tocatch the recoil products. The ions used were 35 and 95
MeV jnucleon 40 Ar and 35, 70, and 135 MeV jnucleon
14N. The irradiation was done for 3 to 4 hours in the
beam current ranging from 50 to 200 enA. Each catcher
foil was subjected to the off-line ,-ray spectrometry.
The activity distributions of the recoil products wereobtained from the main ,-ray intensities observed in
the individual catcher foils. Differential ranges obtained from the activity-per-thickness were presentede10~--------~-------.

•~ oi i• 9•

0.1

135MeV/uo 70MeV/u
f::,.

It

35MeV/uf•

in Fig. 1 for 43K, 57Co, and 61Cu in the Cu + 14N
systems. The recoil range and its width are extremely
small for the target-like product; those for the spallation products increase with the decrease of the productmass. They also decrease with the increase of the projectile energy, as described previously. 1) The quantitative discussion on the momentum distribution will begiven after conversion of the recoil range to the recoil
momentum or energy.
We assumed that the peak position of the range distribution is equivalent to the longitudinal momentum
transfer and the width corresponds to the isotropic velocity of the product. Figure 2 shows the correlation
between the longitudinal momentum per product mass
(PI I j A) and the isotropic velocity (V) of the typical
products (43 K, 51Cr, and 61Cu), which was deduced
from the recoil range data based on the above assumption. The latter is the measure of the excitation energy
in the precursor of the spallation process following thecollision step. One can see an approximately linear
relation between PI I j A and V. The reaction mechanism will be discussed from the collision kinematics
obtained here in addition to the systematic data about
the average recoil ranges and product yields measured
previously.

Q) 0.01

1.5,.------------,

.~

~

a;
!;.

f::,.

•
•

N

'E
U
C, 0.1
E

57

f::,.

0

en

eo

11
0

•

Q.

U 0.01

61CU
L!Jf::,.

••
0.1•

OL-_...L-_-L-_.....L.._......L_---J

o

f::,.

20

30

40

50

PII fA (MeVfcfu)

0

~

0.01
0

10

2

3

4

5

Range (mg*cm-2)

Fig. 1. Differential recoil ranges of typical recoil productsin the Cu + 14N systems.

Fig. 2. Correlation between the longitudinal momentum
per product mass (PI! / A) and the isotropic velocity(V) of the recoil product. 0: 43K, e: 51Cr, and 6:
61Cu.

References
1) E. Taniguchi et al.: Radiochim. Acta, 62, 163 (1993).

127

RIKEN Accel. Prog. Rep. 29 (1996)

Mass Transfer in the Heavy-Io'n Reaction of 197Au
Induced by 136Xe
A. Yokoyama, T. Saito, H. Baba, A. Shinohara, M. Furukawa, and Y. Ohkubo
Deep inelastic reaction is an important process in theheavy-ion-induced reaction especially for the energy region above 10 MeV lu, where the other processes suchas fragmentation also have substantial cross sections.
It is difficult to predict the complicated processes ofheavy systems such as gold plus xenon since the nuclear fusion process is hindered by Coulomb repulsion
for the heavy systems. It is reported in Ref. 1 thatthe three-body interaction contributes to the reaction
mechanism of a gold plus xenon system. It is also reported in Refs. 2 and 3 that a deep inelastic reaction
plays an important role in the above system.
In the present study, we measured the mass distribution and the differential ranges of the products from areaction of 197 Au with 23 MeV lu 136Xe ions by using aradiochemical method in order to investigate the reaction mechanism of the relevant system and add further
information to it.
The experiments were carried out at the RIKEN ring
cyclotron (RRC) facility. The targets of Au metal foils
were of 18.81 mg/cm 2 in thickness. The target was
sandwiched by three Al foils of 25 /-Lm in thickness andone Al foil of 50 /-Lm in thickness for the measurementof short-lived nuclides. Two of the Al catcher foils were
replaced by 50 J..lm Kapton ® foils for the measurementof long-lived nuclides. The projectile energy of the ionswas 26 MeV I u and the energy at the center of the target foil was 23 MeV I u. The details of the experiment
are the same as described elsewhere. 4 )Figure 1 shows the yields of the product nuclei observed in each foil of the stack of a target and catchers. The observed products are widely distributed in
the mass range between 30 and 200 in atomic massunit for the target foil and a forward foil (Au3). The
yields of products of masses near the mass of the target or the projectile nuclide are increased. It may be
due to the contribution of a peripheral reaction suchas a mechanism of nearly grazing trajectory. A lot of
products with masses less than 120 amu are observedin the most downstream foil and consequently havelong ranges. They are considered to be produced via afission process and multifragmentation. The distribution of the mass region between 150 and 190 exhibits
the characteristics of the target fragmentation. Many
neutron deficient nuclides are concentrated in the mass

128

XE-136 + AU-197
10 2 ~"'T""""""T--"-""""""'T""""""T--..-.,-,--,---y--"-""",,,--,-,---,--,•o

TARGET
AU3

(a)

I

o

100
XE-136 + AU-197

2

10

200

..

AU4

/':,

AU5

I

(b)

o

I

100

200

MASS ill

Fig. 1. Formation cross sections of the products in eachfoil of the stack for the 197 Au and 23 MeV lu 136Xe
system. The foils of Au3, Au4, and Au5 are forward
catchers in order of the distance from the target foil.

region around 100 amu. It means that these nuclides
are produced via a system which has a large excitationenergy and causes evaporation of many nucleons. The
results support the possibility of a three-body process
following the substantial dissipation of the projectile
kinetic energy.
References
1) O. Granier et al.: Nucl. Phys., A481, 109 (1988).
2) A. Yokoyama et al.: Phys. Rev., C46, 647 (1992).
3) W. Loveland et al.: Phys. Lett., B312, 53 (1993).
4) H. Kusawake et al.: Radiochim. Acta, 69 , 65 (1995).

RIKEN Accel. Prog. Rep. 29 (1996)

Reaction of (14, 15 N

+ 165Ho) and (40Ar, 14N, + 141Pr) Systems
at Intermediate Energies

K. Mukai, A. Yokoyama, T. Saito, H. Baba, Y. Ohkubo, A. Shinohara, and M. Furukawa
In the heavy ion reaction studies many reaction
mechanisms have been proposed for a wide variety of
projectile-target combinations and beam energies. We
have studied complete and incomplete fusion for thereactions of 165Ho with 35, 70, 135 MeV/nucleon 14N,
and 141 Pr with 35 MeV/nucleon 14N and 10, 25, 38, 59,
95 MeV/nucleon 40 Ar beams using the thick-target,
thick-catcher recoil range techniques.
In the present work we carried out angular distribution experiments for the (35, 70 MeV/nucleon 14,15 N+ 165Ho) system in order to investigate precisely the
incomplete fusion mechanism in each mass region. We
performed the experiments at the RIKEN Ring Cyclotron E3b course using the radiochemical method.
A cylindrical box made of Lucite was set in an irradiation chamber of the course. A 165Ho target , which
was inclined to 23.7° with respect to the beam direction, was bombarded by 14 N ions for about two hours.
The 165Ho targets were made by spattering on the 30
J.Lg/cm 2 carbon backing. The target thicknesses were0.10 mg/cm 2 for the 35 MeV/nucleon experiment and0.26 mg/cm 2 for the 70 MeV/nucleon experiment. Mylar films with 14.3- 100 J.Lm in thickness were attachedto the inside wall of the cylindrical box. The beam
spot was narrowed with two slits and the beam intensity was monitored with a Faraday cup. After irradiation, the catcher foils were splitted into seven pieces
and assayed by Ge ')'-ray spectrometers.
In the previous experiments the longitudinal momenta transferred (LMT) along the beam direction
were determined from the measured cross sections
and average forward ranges (FW). The details of calculation are described elsewhere. 1) There are considerable discrepancies between observed values andLeray's systematics,2) which is often referred to explaining incompleteness of the system irrespective of
the projectile-target combination. It was found thatthe averaged value of P 11/ Pen of the 14N + 165Ho system was comparable to that of the 14N + 141 Pr system,and that the target mass seems to have little influenceon the entrance channel dependence of the incomplete
fusion process. The discrepancy is concluded to reveal
the effect of the energy and angular momentum of the
projectile.
Differential cross ' sections for 87ym, 111 lng, 135 Ce g ,160Er are shown in Figs. 1 and 2. From the distribution in 35 MeV/nucleon and 70 MeV/nucleon 14N experiments the angular distributions are observed to be

more forward peaking as the mass number increases.
The distribution of 87ym , which would be a fission
fragment, extends to larger angles compared to otherproducts. Interpretation of these angular distributions
is in progress.

I

I

I

o 87y'"b.

llJIn g•J3° Ce g

•

J6°Er

-

I

GO

I

120

180

(deg.)

Fig. 1. The angular distributions of the products in the
70 MeV/nucleon 14N experiment.

o 87yrn

10-1b.

l11In g•

135Ceg

180

0
81ab

(deg.)

Fig. 2. The angular distributions of the products in the
35 MeV/nucleon 14N experiment.

References
1) K. Mukai et al.: OULNS Ann. Rep., p. 115 (1993) .
2) S. Leray: J. Phys. C, 4, 275 (1986).

129

RIKEN Accel. Prog. Rep. 29 (1996)

Multitracer Study on the Behavior of Various Elements in
Atmosphere-Plant System
T. Shinonaga,* S. Ambe, S. Enomoto, H. Maeda, M. Iwamoto, T. Watanabe, and 1. Yamaguchi
Many works have been done on the pollution ofplants with airborne elements and the importance of
airborne elements in health physics was demonstrated.
However, most of the previous studies did not clearly
distinguish between the absorption via roots and that
via leaves. Here, we studied the direct absorption of
atmospheric elements by soybean plants using the radioactive multitrac8r technique.
A radioactive multitracer was prepared from an Au
target irradiated with 135 MeV jnucleon 14N at the
RIKEN Ring Cyclotron. Soybean seedlings were cultivated in a box where multitracer-adsorbed cellulose
powders were floating in air. Detailed experimental
procedures were described in a previous report. 1)
Monitors were placed beside the soybean plants fordetermination of distribution of the multitracer in thebox. They were constructed of glass fiber paper witha structure similar to that of the soybean plant.
Amounts of absorbed elements are expressed in relative values by dividing the peak area in ')'-spectra of
1 g of dry samples by the corresponding peak areaof a given portion of the multitracer. About 0.2% of
the multitracer was absorbed by the soybean, of which
80% was found in the leaves, and 10% each in beans
and stems.
Relative amounts of elements in the monitors were
almost the same irrespective of the position. This indicates that the radioisotopes were uniformly distributedin the box. The relative amounts of elements in theleaves , beans and stems markedly differ depedendingon the element .
Distributions of elements in green and brown leaves
originating from the middle node are shown in Fig. 1 (a)and (b) together with relative values of the monitor.
It is remarkable that Se was accumulated in large
amounts in both green and brown leaves , although thevalue for green leaves was lower than that for brownleaves. Relative amounts of Sc, Y , Eu, Gd , Vb, and Ir
were several-fold higher in brown leaves than in green
leaves. The relative amounts of Co, As, Se, and Hf
were 2- to 3-fold higher in brown leaves than in green
leaves. However , there was little difference in the relative amounts of Mn, Rb, and Sr between green leaves
and brown leaves.
The tendency for high Se accumulation also occurs

Present address: Institute of Heavy Ion Physics, Peking University, China

130(a) Green leaves(b) Brown leaves
500
400

Fig. 1. Relative amounts of elements in (a) green leavesand (b) brown leaves. White bars indicate the valuesof monitor.

in the beans and this appears more clearly in the seeds
than in the pods as shown in Fig. 2(a). It is interesting
to note that although the seeds were not physically
exposed to the multitracer-adsorbed cellulose powders
durjng growth, high amounts of Co, Se, and Rb wereobserved in the seeds. Scandium, Y , Eu, Gd, Hf, andIr were not observed in the seeds.
10060(b) Stems(a) Beans
80

Q

•
0

60

Pod
Seed
Monit or

50
•
•

40

TunicaCorpuso Monitor

30

40~ ': '" .LLL

y "'''' YO '"':;'.

Element

W,~~:AJj~llLl,<Jl.al...L:,jUl.ll.J
Element

Fig. 2. Relative amounts of elements in (a) beans and (b)stems.

Since the soil was covered with films , there was little
absorption of the elements by the soil, and no ')'-raypeaks were observed in the root. These results offer
evidence that the elements observed in the leaves weredirectly absorbed from air and that the elements observed in beans are due to transport from the leaves
after their absorpti'on through the leaf cuticle.
References
1) T. Shinonaga et al. : RIKEN Aceel. Prog. Rep. , 28 , 85
(1995).

RIKEN Accel. Prog. Rep. 29 (1996)

Determination of Trace Elements in Ferns by
Neutron Activation Analysis (I)T. Ozaki, S. Enomoto, Y. Minai, S. Ambe, F. Ambe, and T. Tominaga
Importance of trace elements in life systems was firstrecognized more than one hundred years ago. However,accumulation of trace elements in ferns has not beenstudied well because ferns are regarded as the species
somewhat backward in evolution as compared with theangiosperms or the gymnosperms. It is noteworthy
that pteridophytes also have become abundant and diverse in evolution after diverging from other plants.
Studies on accumulation of trace elements in pteridophytes should reveal an unexpected phenomenon because specialization in evolution often reaches extraordinary features. In this article, we report accumulation of lanthanides in ferns. Accumulation of otherelements will be summarized in a following paper inthis volume.
About 70 kinds of fern samples have been analyzed
by means of the neutron activation analysis . The fern
samples were collected at the Koishikawa Botanical
Garden, School of Science, University of Tokyo. Several kinds of the ferns were sampled at the same place
twice or three times over a year to examine seasonalvariations in their elemental compositions. The plant
samples were immediately packed in polyethylene bags
at the sampling location. The samples were rinsed
gently with distilled water and then with ultrapurified water. Their bodies were divided into mesophylls
and leafstalks for analysis. When the samples could
not be divided into these two parts, as in the case of
Psilotum nudum (a whisk fern) or Equisetum ramosissimum (a scouring rush), the whole bodies were used.
The samples were air-dried for one week at room temperature. 100- 150 mg of each sample was sealed ina small polyethylene bag for irradiation. Neutron irradiation was carried out at the TRIGA-II reactor at
Atomic Energy Institute, Rikkyo University. Gammaray spectra were measured twice by an HPGe detector
coupled with a 4096 multichannel analyzer after 1 weekand 2 weeks of cooling.
Concentrations of lanthanides in plant tissues are
generally very low. 1 ) However, the concentrations (dryweight base) in most samples were higher (Fig. 1) thanthose in the ordinary plants (e.g. , 0.003- 5 ppm).2) In
particular, the fern samples accumulated lighter lanthanides (La and Ce). Lanthanu.m was found to be
most abundant in the fern samples (more than 20 ppm)
except for some cases where Ce showed higher concentrations than La.
Here, we define concentration ratio (Ri) as follows:
Ri = Ci ,(fern)/Ci,(soil)
where Ci ,(fern) and Ci ,(soil) represent concentrations of

=
o
~
=
8=
'<:1
Go)

(.)

0

5

10

15

Number of species

Fig. 1. Concentration distribution of La in fern samples.

an element i in a fern and the surrounding soil, respectively. The concentration ratio indicates the degree ofaccumulation of each element in the ferns. The concentration ratio varied regularly with the atomic number of the lanthanides, except for Ce (Fig. 2). Cerium
tends to occur as tetravalent in the environment. The
difference in oxidation state between Ce and other lanthanides may cause the anomaly in the plot.

o0 . 25.-------~

0.4, . . - -- - - --.~ 0.3.~(a)e.g= 0. 15

=

o

'<:1

S 0.2
~

g 0. 1

(b)
0.20

~

C 0. 10LuGo)

8 OO+----.-----.----j
Yb
Ce
0.80

0.90

1.00

Ionic radius (A)l.10(.) 0 58°'Luo. oo+--_Y-,-;b'--_~--I
0.80

0.90

1.00

1.10

Ionic radius (A)Fig. 2. Concentration ratios of lanthanides in (a) Crytomium fortunei and (b) Dryopteris yakusilvicola.

In recent years , special attention has been paid tobiological roles of rare earth elements. It has beenreported that many plants can discriminate against
lanthanides. 3 ,4 ) On the other hand, there are many
reports concerning beneficial effects of rare earths on
the production of plants even though no evidence has
been revealed that they are essential elements. A multitracer from an Au target irradiated in RIKEN Ring
Cyclotron contains many kinds of radionuclides of lanthanides. Application of the multitracer technique
should be useful for the elucidation of uptake mechanisms of lanthanides and their roles in growth of ferns.
References
1) P. Linsalata et al.: Health Phys. , 33, 56 (1989).
2) M. Koyama et al.: J. Radioanal. Nucl. Chern., 112, 789(1987).
3) N.A. Campbell et al.: J. Exp. Bot., 25, 61 (1974).
4) K. K. Harmet: Plant Physiol. (Bethesda), 64, 1094
(1979).

131

RIKEN Accel. Prog. Rep. 29 (1996)

Determination of Trace Elements in Ferns by
Neutron Activation Analysis (II)T. Ozaki, S. Enomoto, Y . Minai, S. Ambe, F . Ambe, and T. Tominaga
present work. While a ny role of Sc in life systems has
not been reported, t he extraordina rily high concentration suggests that Sc is involved in some biological activities in some ferns . It is notewort hy t hat Sc accumula tor species tend to concentrate Cr , Fe, and Co. This
is indicative of similarity in the uptake m echanism fort hose elements. Although Cr is usually toxic to living bodies, the species listed in Table 1 showed highconcentrations of Cr. Those species possibly have special mechanisms for utilizing Cr or for neutralizing its
toxicity. Zinc · was found to be very abundant in som e
species: more than 1000 ppm in Asplenium cheilosorum and Lygodium japonicum. Since it was reported
that the Zn concentrat ion ranged from 2 to 100 ppm
in ordinary plants,1) those sp ecies could be regarded
as an accumulator of Zn.

As presented in a preceding paper , ferns tend to accumulate lanthanides (in particular, La and Ce). The
analytical results indicated that some of other trace elements were also accumulated in ferns . In this report,
we summarize accumulation of trace elements foundin the analysis, except for lanthanides described in thepreceding report.
Neutron activation analysis was employed to determine Ca, Sc, Cr, Fe, Co, Zn, Rb , Cs, Ba, La, Ce, Sm,
Eu , Yb , and Lu. Experimental procedures were described in the preceding paper.
The accumulator species newly found in this work
are summarized in Table 1. The concentration of Sc
in ordinary plants reported by Koyama and his coworkers ranges form 0.002 to 0.01 ppm,1) whereas Stegnogramma griffithii showed about 4 ppm Sc in the

Table 1. Accumulator species for each element found in this work.
Element

Species

Genus

Concentration (ppm)Concentration range forordinary plants (ppm)l)Sc

Stegnogramma griffithii
Asplenium trichomanes
SelagineLla tamariscina

Stegnogramma
Asplenium.SelagineLla

3 .9
2 .0
1.5

0.002 - 0.01

Cr

Stegnogramma griffithii
Asplenium trichomanes
Selaginella tamariscina
HymenophyLlum barbatum

Stegnogramma
Asplenium
Selaginella
Hymenophyllum

25
12
6.4
6.4

0.02 -1.0

Fe

Stegnogramma griffithii
Psilotaceae
Asplenium trichomanes
Selaginella tamariscina

Stegnogramma
Psilotum nudum
Asplenium
Selaginella

870
530
470
380

20 - 200

Co

Stegnogramma griffithii
Asplenium trichomanes
Selaginella tamariscina

Stegnogramma
Asplenium
Selaginella

4 .0
2.2
1.3

0.005 - 1.0

Zn

Asplenium cheilosorum
Lygodium japonicum .
Asplenium hondoense

Asplenium
Lygodium
Asplenium

1900
1100
580

2 -100Ba

Dicranopteris linearis
AspLenium hondoense
BLechnum niponicum

Dicranopteris
Asplenium
Blechnum

380
330
240

10 -100

La

Dryopteris erythrosora
AspLenium cheiLosorum
Asplenium trichomanes
Asplenium hondoense

Dryopteris
Asplenium
Asplenium
AspLenium

32
23
21
14

0.003 - 5

Tracer technique is very useful to deduce uptake andaccumulation mechanisms of trace elements in the living organisms. A carrier-free multitracer produced in
RIKEN Ring Cyclotron by irradiation of an Ag target contains many kinds of radionuclides of essential
elements for plants and some other elements whose
biological roles are unknown. This technique should132

provide a clue to the elucidation of mechanisms concerning the uptake process and accumulation of theelements in ferns.
References
1) M. Koyama et al.: J. Radioanal. Nucl. Chern., 112, 789(1987).

RIKEN Accel. Prog. Rep. 29 (1996)

Distribution Coefficients of Platinum Group Metals between Soil
Solid and Liquid Phase
H. Yasuda, S. Ambe, and S. Uchida*In these days, high-tech industries are developing
and producing new materials by synthesizing selected
elements and considerable amounts of some rare metals are released to the environment. For evaluating
and preventing the adverse health effect to humans,
behavior of those metals in a real environment needs
to be accurately t raced. However, little informationon the environmental behavior of selected rare metals, particularly platinum group metals, is available
for this purpose. 1) Then, in this study, distribution coefficients (KdS) of three platinum group metals (Rh,Ir, and Pt) were measured for Japanese agriculturalsoils using a multitracer technique. The Kd is defined
as a concentration ratio between soil solid and liquid
phase and generally used in radiological environmental
impact assessments for representing radionuclide sorption characteristics onto soil.
The radioisotopes of platinum group metals (101 Rh,
189Ir, and 191 Pt) were produced by irradiating a thingold foil with a 14N beam (135 MeV/nucleon) in
RIKEN Ring Cyclotron. The isotopes generated wereseparated from the Au target and the pH was adjusted
finally to 0.05 M HCI. The contact solution was a rainwater (pH 4.5 , electric conductivity 0.065 mS em-I)
collected using a stainless steel bottle placed outdoorsat Tokaimura, Japan; it was filtered through a 0.45 11m
membrane filter and kept in a refrigerator. As samples
of solid phase, sixteen agricultural soils were collectedfrom cultivated lands in Japan; the soils sampled werepassed through a 2 mm sieve, and dried at room temperature for about one month. The soils were analyzed
for 8 chemical properties: cation exchange capacity(CEC), anion exchange capacity (AEC), exchangeable
potassium content (exch.K), exchangeable Ca content(exch.Ca), activated aluminum content (activ.Al), activated iron content (activ.Fe), total carbon content(total C), and total nitrogen content (total N). The
probability distributions of these chemical properties
showed log-normal type distributions. 2 )The KdS were measured by a batch technique. Plastic bottles (50 mL) containing 3 g of each soil received
30 mL of the contact solution (rainwater) with 0.2 mLof the multitracer solution. The bottles were shaken
at 100 rpm keeping the temperature at 21°C. After 20
hrs, each bottle was centrifuged at 3500 rpm and thesupernatant solution was passed through a 0.45 11m
membrane filter and measured for the ,-ray intensitywith aGe-detector (Ortec, GEM-30185) coupled witha multichannel analyzer (Seiko, EG&G 7800). The Kd
Division of Radioecology, National Institute of Radiological
Sciences[L kg-I] was calculated by the difference of radionuclide concentration in the supernatant.
The KdS obtained here were examined for theirvariational characteristics, i.e. probability distribution
types and correlations with the soil properties. The
cumulative probability distribution of each nuclide Kd
is shown in Fig. 1. The platinum KdS were larger than
. those of other two metals and the rhodium KdS showedlarger variability compared to the iridium Kds. The results of Shapiro-Wilk test indicated that the probability distributions of these nuclide KdS were not normal
type distribution but log-normal one. In the resultsof correlation analyses between the KdS for rhodium
and iridium and the soil properties (Table 1) , adequate
correlations were observed with the selected properties
relating to the amount of clay, i.e. activated aluminum
and activated iron contents. The platinum KdS did notshow a positive correlation with any chemical propertyof soil.
••••• r-o-~~~~...---~~~

..

••••

~

I!
P:

o

o .. A
:/

!

'1'

,r>

,;,.

.1

.01 L....."":1~OO::--"~~:;::;::::::==~

Fig. 1. Cumulative probability distributions of the KdS of
101Rh, 1891r, and 191pt obtained for 16 Japanese agricultural soils .
Table 1. Spearman correlation coefficients between the
KdS and the chemical properties of the soils.

nuchde n
IOIRh

189Ir
191Pt

CEC

AEC exch. exch. actIvo actIvo total total
K

Ca

AI

Fe

C

N

12 0.80* 0.66 0.29 0.56 0.87* 0.83* 0.90* 0.88*
15 . 0.54 0.53 0.07 0.13 0.89* 0.71 0.53 0.48
15:0.18 -0.12-0.11-0.32 -0.09 -0.11 -0.21-0.25*The coefficient value is larger than 0.80.

In future researches, it is desired to confirm the sorption equilibria and to clarify the effects of other environmental factors such as temperature, co-existing ion
concentrations, and oxidation state.
References
1) A. Kabata-Pendias et al.: "Trace Elements in Soils andPlants", CRC Press, Boca Raton, p. 293 (1992).
2) H. Yasuda et al.: Water Air Soil Pollut. , 83, 85 (1995).

133

RIKEN Accel. Prog. Rep. 29 (1996)

Group Separation of a Multitracer by Solvent Extraction
B. Liu, S. Ambe, S. Enomoto, H. Maeda, R. G. Weginwar, and F. Ambe
1. Solvent Extraction of REE
In the course of the multitracer studies, we obtainedinteresting results on distributions of rare earth elements (REE) in rats and mice. For these studies, using only REE tracers was found to be more convenient
than using the whole multitracer. The multitracer contains radioisotopes of Sc, Y and lanthanides from Ce
to Lu. 1 ) We studied the conditions for the simultaneous extraction of REE from the multitracer solution
and their back extraction in order to obtain a group of
tracers consistinng of only REE (Hereafter, the tracer
elements are denoted by the symbols of the elementswith an asterisk. Note that they are all in the carrierfree state).
Di(2-ethylhexyl)orthophosphoric acid (HDEHP)
was used for extraction of REE from the multitracer
solution.2) Extraction was first carried out using 0.02
mol dm- 3 HDEHP-toluene, since the REE are present
in trace amounts. In this case, the extraction efficiency was about 0% for Ce*, 50% for Eu* , and 100%for Lu*. When the concentration of HDEHP was increased, the extraction efficiency of Ce* increased withthe concentration of HDEHP, as shown in Fig. 1. It
was found that n-heptane gave higher extraction yields
than toluene when used as a diluent. Although thedifference in the extraction efficiency was small between HDEHP-toluene and -n-heptane at a low concentration of 0.1 mol dm- 3 HDEHP, heptane yieldedhigher efficiency exceeding 90% at 0.4 and 0.5 mol
dm- 3 HDEHP (Fig. 1). Under the optimum conditions
found in this study, practically all the REE in the multitracer were extracted. Namely, we used 0.4 mol dm- 3

100 ~------------------~--~-0- toluene-0- heptane
0+----.----.----.----~--_4

0.1

0.2

0.3

0.4

0.5

0.6

HDEHP-heptane for extraction of REE from 0.05 mol
dm- 3 HCl. All of Zr* and Hf* , 60% of Fe* and40% of Zn* were co-extracted with 0.4 mol dm- 3
HDEHP-n-heptane. Back extraction was carried out
with an equal volume of 8 mol dm- 3 HCI after theorganic phase was diluted by adding the same volumeof heptane. Yttrium*, Ce*, Eu*, and Gd* were completely back-extracted and for Yb* and Lu*, the backextraction efficiency was 95 and 90%, respectively.
Iron* and Zn* were also back-extracted completely.
In contrast, Zr* and Hf* were not appreciably backextracted even with either conc. HCI or conc. HN0 3 .
2. Solvent Extraction of Tc and Re
Nowadays, technetium and rhenium have become
very important for use in environmental and medical
studies. Although Tc* and Re* were produced by irradiation of an Au target, they were evaporated andtrapped together with an acidic solution in a coolingflask during the dissolution of the Au foil and the evaporation of the resulting solution. With an aim to include these two elements in the multitracer, we alsostudied how to collect Tc* and Re* from the trapped
solution.
Two cm 3 of a highly acidic solution of Tc* and Re*
collected in the cooling flask of the evaporator was adjusted with NaOH to pH higher than 12, and thena few drops of H 2 0 2 were added. The solution was
warmed with a water bath for 10 min. Then Tc* andRe* were extracted with an equal volume of MEK . After phase separation, the organic phase was diluted
with CCl 4 and shaken with the same volume of distilled water twice. Both elements were back-extracted
into the aqueous phase.
Because only Re(VII) and Tc(VII) are extracted by
MEK, the extraction efficiency was relatively low in theabsence of H 2 0 2 . Only about 70% and about 50% of
Tc* and Re*, respectively, were extracted into the organic phase. After the addition of H 2 0 2 , however, theextraction efficiency for Tc* increased to about 100%and that for Re* to greater than 80% . This is thoughtthat the presence of H 2 0 2 prevents the reduction ofTc(VII) and Re(VII) by MEK or some organic impurity in it. As regards the back extraction, more than
90% of Tc* and Re* in the solvent were back-extracted
after two extractions with an equal volume of the aqueous phase.

Concentration of HDEHP / mol dm- 3

References
Fig. 1. Extraction efficiency of Ce(III) from 0.05 mol
dm- 3 HCI with HDEHP.

1341) S. Ambe et al.: Anal. Sci., 7 , Suppl., p. 317 (1991).
2) K. Kimura: Bull. Chem. Soc. lpn., 33 , 1038 (1960) .

RIKEN Accel. Prog. Rep. 29 (1996)

Group Separation of a Multitracer by Cation Exchange Column
B. Liu, S. Ambe, S. Enomoto, H. Maeda, R. G. Weginwar, and F . Ambe
From an Au target, a multitracer solution containing
a large number of radioisotopes of elements from Be to
Hg was obtained. 1) The multitracer solution gave complex ,-ray spectra consisting of more than 400 lines,
resulting in overlapping of peaks and peaks hidden by
the background. Previously, we used the whole multitracer without further separation. However, we soon
realized that the overlapping of peaks is serious and reduction of the number of radioisotopes can increase thenumber of those effectively used as tracers. There arealso specific demands for tracers containing a relatively
small number of radioisotopes such as those of alkaline
metals and of the platinum group. Among them, there
are some carrier-free radioisotopes such as those of Rb
and As, which are not commercially available, especially in a carrier-free state. In response to these demands, we studied the separation of the multitracer
into several small groups by the methods of cationexchange. We aim at the development of separation
methods to yield carrier-free and salt-free radioisotope
tracers for further application of the multitracer technique to chemical and biological studies (Hereafter, thetracer elements are denoted by the symbols of the elements with an asterisk. Note that they are all in the
carrier-free state) .
A multitracer solution was evaporated to dryness
and the residue was dissolved in 10 cm 3 of a 0.5 mol
dm- 3 HCI solution. The solution was then poured
on a chromatographic column filled with Dowex W50XS (100- 200 mesh , H+ form , 15 cm high and O.S cm
LD.) previously equilibrated with distilled water andwashed with 0.5 mol dm- 3 HCI. Two elution procedures were performed. Procedure I: The column waswashed with 20 cm 3 of 0.5 mol dm - 3 HCI, 40 cm 3 of 2
mol dm- 3 HN0 3 , and 40 cm 3 of 6 mol dm - 3 of HN0 3
successively, as shown in Fig. 1. Every 2 cm 3 of theeluate was collected in a test tube and was subjected
to ,-ray spectrometry. Procedure II: The column was
eluted with 20 cm3 of 0.5 mol dm - 3 HCI, 20 cm 3 of
0.1 mol dm- 3 H 2 C 2 0 4 solution in 0.5 mol dm- 3 HCI
40 cm3 of 2 mol dm- 3 HN0 3 and finally 40 cm 3 of 6'
mol dm- 3 HN0 3 , as is also shown in Fig. 1.
In the first 0.5 mol dm - 3 HCI elution common to
Procedures I and II, Pt*, Ir* , Rh* , Ag* , Re* , As* , andSe* radioisotopes were eluted from the cation-exchange
column. It is considered that Pt* , Ir*, and Ag* exist
as chloro complexes and As*, Re* and Se* as oxyanions. In the second elution of Procedure I with 2 mol
dm - 3 HN0 3 , In*, V*, (Na*, K*, Rb*, Cs*), (Be*,Mg*, Ca*, Sr*, Ba*) , Mn*, Co*, Cu*, Zn*, and Ga*

Procedure II

Pt. Ir. Rh, Ag, Re, As, Se

Procedure I
O.S mol dm ·3
HCI

Cation0.1 mol dm·3
oxalic acid in
O.Smol dm·3
CI
In, Hr, Fe. Zr, Sc , Oa

Alkaline earth
metals andCu. Mn , Co,
Zn
REE (except Sc)

2 mol dm·3
HN03

Pt. Ir. Rh, Ag. Re. As , Se

Col umn
Dowex
WSO·X8

AlkalIne
metal sO.Smol dm·3
HCI

Exchange

2 mol dm·3
HNOIn, V andAlkaline metals:
Na, K. Rb, Cs,
Alkaline eanh metals:
Be, Mg. Ca, Sr. Ba
and Cu , MIl, Co, Zn,
Oa

100·200
mesh
H+ form

6 mol dm·3
HN03

ISXO.80cm

6 mol dm'
HN03

CREE and Sc, Fe
Zrand Hf

Fig. 1. Elution chart of group separation from the multitracer by cation exchange.

were successively eluted. By collecting the eluate insmall portions, they were divided into alkaline metal ,alkaline earth metal and other divalent and trivalent
metal groups. Finally, with 6 mol dm- 3 HN0 3 , REE
were eluted out. It was found that Sc* and Fe* werealso eluted out with lanthanides. Zirconium* and Hf *which were strongly adsorbed on the resin, were elutedout after REE with substantial tailing and the recoveries of these two elements were poor. A very small partof the radioisotopes of Ir also appeared in other fractions , which indicates the complicated chemical formsof Ir*.
The difference of Procedure II from I is that, in theformer, 0.1 mol dm- 3 oxalic acid solution in 0.5 mol
dm- 3 HCI was used as the second eluting solution. The
merit of procedure II is that Zr* and Hf* are eluted
completely from the resin. This method is therefore
recommended when recoveries of Zr* and Hf* are necessary. A 0.1 mol dm- 3 oxalic acid solution in 0.5 mol
dm - 3 HCI was used for the removal of Fe and Sc interferences from geological materials. 2 ) We found that
In* , Zr*, Hf*, and Ga* were also eluted besides Fe*
and Sc* using this eluent, while the other elements remained strongly adsorbed on the resin.
References
1) S. Ambe et al.: Anal. Sci., 7, Suppl., p. 317 (1991).
2) S. Meloni et al.: J. Radioanal. Nucl. Chern., 71, 429(1982) .

135

RIKEN Accel. Prog. Rep. 29 (1996)

Biodistribution Study of Antibodies Labeled with
Multitracer in MiceB. Liu, S. Enomoto, S. Ambe, and F. AmbeIn the field of radiopharmaceutical science, radioactive metal ions chelated to small molecules, peptides,
or proteins such as monoclonal antibodies have beenused clinically for diagnosis of cancers and for basic
studies on functions of various organs. In the selection of suitable isotopes for radiopharmaceutical uses ,we usually label a compound with different isotopes
one by one and compare their in vitro and in vivo behavior, which involves tedious work. Moreover, slightchanges of conditions are inevitable in these separate
experiments. In the multitracer technique developed
at RIKEN, a large number of radioisotopes producedby high-energy heavy-ion irradiation of a metal target are simultaneously used as tracers. This is a great
advantage for biological, pharmaceutical and medical
studies. With the multitracer technique, we can obtain much information at one time and under strictly
identical experimental conditions.
In this work , labeling of antibodies, immunoglobulin
G (IgG) with a multitracer was investigated and themetabolism of the labeled antibodies was studied. I)
A carrier- and salt-free multitracer solution in 0.05
mol·dm- 3 hydrochloric acid was prepared. Diethylenetriaminepentaacetic acid (DTPA) was conjugated to
IgG by the cyclic dianhydride method. After the multitracer solution was added to the IgG-DTPA solution,
IgG-DTPA-multitracer was separated from free multitracer ions by means of a molecular-cut filter. To determine the in vitro stability of incorporated isotopes, thelabeled IgG preparations were dialyzed against saline
and 0.1 mmol·dm- 3 EDTA solutions and the radioactivity remaining in the dialysis bags was measured withan HpGe detector. As a control, the same labeling procedure was performed with another IgG solution without conjugation with DTPA. In animal experiments,
the antibodies labeled with multitracer were injected
intraperitoneally into mice. The mice were sacrificed
at 3, 24, and 48 hr after injection. Different organs
were dissected, weighed, and counted with HpGe detectors. The biodistribution data were computed aspercentage of injected dose (ID) per gram of organs.
It was found that the stability constant of the metal
DTPA complex was a main factor in determining thelabeling efficiency. Labeling efficiency of the metal ionsin the multitracer solution increased with the stability
constant of the DTPA complex. For the control sample without DTPA, the amounts of radioisotopes combined with IgG were lower than the detection limit. No
obvious loss of the radioisotopes from the labeled IgGDTPA was detected during 48 h of dialysis in saline
and EDTA solutions. This indicates that once metal

136

ions combine with IgG-DTPA, the chelates are stable
under the conditions studied.
The in vivo properties of multi tracer-labeled IgG
show that the stability constant of the DTPA-metal
complex is only one of the factors that affect the biodistribution of radioisotopes. The property of the metal
ion is also very important. Figure 1 shows the biodistribution of 10 radiotracers which were labeled on IgG.
The metabolism rate of rare earth elements which canform very stable complexes with DTPA such as Y, Eu,
Gd, and Yb was slow in blood, which is a metabolic
characteristic of macro molecular IgG. Although thestability constants of Zr and Hf DTPA complexes arealso very high, they did not show high stability in vivo.
These two elements kept dissociating from the antibodies in blood and accumulated in bones. The rareearth elements showed similar behavior to each other.
However, it seems that the in vivo stability of Ce wasless' than that of Y , Eu, Gd, and Yb. Here maybe thenature of the DTPA complex plays an important role.
From Fig. 1, we can also see that the accumulation targets of the broken-down radioisotopes were different.
Dissociated Ce had high accumulation in liver, while
Zr and Hf accumulated largely in bones.
10 -r---::B::-::I-ood----=----~ [d3hr. :!4hr
D48hr

7.5

5
2.5

o~~~~~~~~

ScCoZnZr Hf YCeEuGd Yb

Elements

Fig. 1. Distribution of multitracer labeled IgG in someorgans.

References
1) B. Liu et al.: J. Radioanal. Nucl. Chem. Lett., 201 , 273(1995).

RIKEN Accel. Prog. Rep. 29 (1996)

Study of Trace Elements Uptake by Tumor-Bearing
Mice by the Multitracer Technique
B. Liu, S. Enomoto , S. Ambe, R. G. Weginwar, and F. Ambe
A variety of radioisotopes injected intravenously
show a higher concentration in tumor than in normal
tissues. 1) Some of these isotopes have been used for
detecting the location of tumors, although the uptaking mechanism of the isotopes by tumors is still not soclear. Taking the advantages of the multitracer technique, we determined the bio-distribution of radioactive elements in tumor bearing mice and compared theuptake of the diverse elements by the tumor.
In the multitracer technique developed at RIKEN,
a number of radioisotopes useful in biological research
are produced by irradiation of different targets withhigh-energy heavy ions. The irradiated target is dissolved in an appropriate medium and the target material is chemically removed leaving the radioisotopes tobe used as radioactive tracers in a solution. The meritsof multitracer technique lie in its high efficiency and its
reliable comparison among each element used as tracer
due to the identity of experimental conditions.
For the production of multitracer, a plate of gold wasirradiated with the 135 MeV/nucleon 12 C beam fromthe RIKEN Ring Cyclotron. The Au target containing
various kinds of radioisotopes was dissolved in aquaregia. The solution was evaporated to near dryness
under a reduced pressure in a rotary evaporator. The
residue in the evaporation flask was dissolved in 3 mol
dm - 3 HCI. Gold ions were completely removed byextraction with ethyl acetate, leaving the radioisotopes
as a multitracer in carrier- and salt-free states. In thisstudy, the radioisotopes of the following 16 elements
found in the mulititracer were used as tracers: Be, Sc,
Zn, Rb, Y, Zr, Te, Ba, Hf, Ir, Pt, ee, Eu, Gd, Yb, andLu.
The experimental mice underwent implantation of
sarcoma in the thigh. One week later, a multitracer
solution in saline was administered intravenously tothe tumor- bearing mice. At 3, 24, and 48 hr after
injection, the mice were sacrificed and the activity ofradioactive elements in the organs was measured using
HpGe detectors coupled with an MCA. As a comparison, a group of tumor-bearing mice, which were administered with a multitracer solution in 0.5 mol dm- 3
sodium citrate, pH 5.0, were sacrificed at 24 hr after intravenous injection. The distribution data were given
as injected dose %/g tissue of tumor/injected dose %/gtissue of muscle (Tumor /M uscle ratio).
Table 1 shows the Tumor/Muscle ratio of 16 elements at 3, 24, and 48 hr after injection in tumor bear-

Table 1. Tumor/muscle ratio of multitracer elements at 3,
24, and 48 hr after injection.
3 hrSaline24 hr
Saline Citrate

48 hr
Saline

Be

1.48

3.07

3.94

3.21

Sc
Zn
Rb
Y

0.65
0.24
0.78
2.60

3.42

3.71

1.51
0.61
17.27

6.98
4.16
1.28
30.86

10.89

Zr

0.58

0.24

6.74

0.34

Te
Ba
Hf

0.69
1.04
0.32

0.86

4.12
3.82
5.67

0.95
2.22
0.73

1.73
0.59

Ir

0.85

1.98
0.43
2.72

3.19

3.00

Pt

0.66

2.29

2.82

2.33

Ce

0.86

2.54

Eu

4.55
.4.40

11.00
14.88

3.69
6.61

Gd
Yb

1.06
2.32
1.57

6.19

8.70
24.09

7.50
10.38

Lu

1.67

6.81

32.00

10.44

ing mice. Generally speaking, alkaline metals such as
Rb and divalent cations such as alkaline earth metals and Zn showed a low Tumor/Muscle ratio. While
the rare earth elements revealed a high tumor-uptake.
On the other hand, Zr, Hf, Pt, and Ir showed low Tumor /Muscle ratio. The mechanism of accumulation of
inorganic elements in tumor is complicated. For reason of the high uptake of the trivalent cations, partly,
it was presumed that hard acids of trivalence would
replace calcium in the calcium salts of hard bases (calcium salts of acid mucopolysaccharides, etc.) present
in tumor tissue. Although Zr and Hf are hard tetravalent cations, these two elements may bind to chloride
and therefore gave a lower Tumor/Muscle ratio. Also
as shown in Table 1, the citrate solution gave a little
higher Tumor/Muscle ratio for most of the elements
studied. It is still not clear whether the citrate helps
to form a certain complex as a ligand in serum andthen results in high tumor-uptake.
References
1) A. Ando et al.: Int. J. Nucl. Med. Biol., 12, 115 (1985).

137

RIKEN Accel. Prog. Rep. 29 (1996)

Separation of a Multitracer from an Au Target Irradiatedby Heavy Ions
R. G. Weginwar, Y. Kobayashi, S. Ambe, B. Liu, S. Enomoto, and F. Ambe
The radiochemical solvent extraction procedure forthe extraction of Au (III) from a solution of an Au target irradiated with an N-14 ion beam has been developed. It is based on the extraction of Au(III) with
ethyl acetate or isobutyl methyl ketone from 3M HCI in
the presence of 2% sodium citrate solution as a masking agent leaving behind a carrier-free multitracer in
an aqueous medium. From the organic phase Au(III)tracer with carrier is then back extracted by 2-amino-2hydroxymethyl-1,3-propandiol in an aqueous medium.
Various conditions, such as pH, HCI concentration,
various solvents, and coextraction of other elements,
in the extraction of Au have been studied.
A piece of gold foil was irradiated with 135
MeV /nucleon N-14 ion beam at RIKEN Ring Cyclotron. After cooling, the foil was dissolved in aquaregia and this solution was evaporated to dryness under reduced pressure and the residue was dissolved in
3M HCl. 1 ,2) An appropriate amount of this tracer solution was taken in a funnel containing 3M HCI and
2% sodium citrate solution as a masking agent andwas extracted with an equal amount of ethyl acetateor isobutyl methyl ketone. After equilibration, theyellow-colored organic phase containing an Au tracers
with carrier was separated out from the carrier-free
multitracer aqueous phase. Then , the organic phase
was back extracted by 2-amino-2-hydroxymethyl-1 ,3propandiol in an aqueous medium. Each phase wascounted on 4k MeA coupled with an HPGe detector
to calculate percent extraction of radionuclides.
Several aqueous systems were prepared in acidic
range and extractions were carried out with ethyl acetate and isobutyl methyl ketone. From Fig. l(a) and(b) it is observed that Au(III) was extracted up to
98% with ethyl acetate and isobutyl methyl ketone at
2-4 M Hel. Maximum extraction was about 95% at
pH 1 and as pH increased the percent extraction decreased. Similarly various other organic solvents were
examined for Au(III) extraction. But only ethyl acetate, isobutyl methyl ketone and diethyl ether were
found to be suitable for extraction of Au (III) with thepercent extraction up to 98% at 3M Hel.
In the coextraction study, it is observed that the coextraction trend of Fe, Re and Sc is similar, i.e. , thoseelements give almost the same percent extraction withboth the solvents. Fe yields the maximum coextraction at 6 M HCI, while Sc shows small dependence on
the Hel concentration. In case of Re, the percent coextraction is much higher with isobutyl methyl ketone
than that with ethyl acetate, and shows a maximum
at 4 and 3 MHCI respectively with both the solvents.
The coextraction of rare earth elements (REE), transition elements and many other elements is being in the138.~- - pH

M

o

_pH

(b)

(a)

~~~~~~~

I

2

3

4

5

,

7

0

I

2

3

4

5

HCI ConcenlMltion

HCI ConoenlraUon

and pH.

and pH.

6

7

Fig. 1. Variation of % extraction of Au(III) by (a) ethyl
acetate and (b) isobutyl methyl ketone with Hel concentration and pH.

range of 2- 5%.
The major coextraction of Re, Fe and Sc is up to 2035%, while the coextraction of Na is about 12% andthat of As and Ru is about 4-5%. Suppression of thecoextraction using a masking agent was also studied
and it was found that the coextraction of Re,Fe,Sc andNa Was depressed to 10-20% and that of REE andtransition elements to 2- 5%.
It was also observed that in the absence of Au(III)the percent coextraction of all these elements is almost
negligible except for Fe and Re. However, as the concentration of Au (III) increases, the coextraction of Re
and Fe sharply increased but that of Ru , Rb, As, Tealso increased marginally. It was also observed that thepercent coextraction attained a plateau for all theseelements examined beyond 100 mg/ml of Au (III) concentration in the system. We also studied the percent
coextraction variation for Sc and Na with increasing
concentration of Au (III) . The percent coextraction wasalmost negligible in the absence of Au(III) , but with
the increase in Au (III) concentration up to 50 mg/ml,
the coextraction increased to about 19% for Sc and
12% for Na. These observations are considered to be
due to the formation of strong ion association complexes of these elements with chloroauric acid in ethyl
acetate or isobutyl methyl ketone in the presence ofHCl. Thus at lower concentrations of Au(III) in theextracting system, the percent coextraction of various
radio elements are depressed down. Except for' Re,
Fe and Sc there is 'no serious co extraction with ethyl
acetate as well as with isobutyl methyl ketone. Thus
the method can be safely used for the extraction ofAu (III) to get a carrier-free multitracer solution which
can be conveniently used for most of the biological andchemical applications.
References
1) S. Ambe et al.: 1. Radioanal. Nucl. Chem. Articles,
195, 297 (1995).
2) F. Ambe: RIKEN Rev., No.4, p. 31 (1994).

RIKEN Accel. Prog. Rep. 29 (1996)

Selective Separation and Reversed Phase Extraction of
Zirconium and Hafnium from Multitracer Solution
R. G. Weginwar, B. Liu, S. Ambe, S. Enomoto, H. Maeda, and F. Ambe
The extraction behaviour of Zr and Hf was studied
in the systems of HCI0 4 - TTA-benzene and HN0 3 - and
HCI-TTA-xylene. 1 ,2) These studies provide little information on the coextraction of other elements. With
the aim to use pure and carrier-free Zr and Hf in themultitracer for the biological study, we have developed selective solvent extraction of Zr and Hf fromthe multitracer using 2-thenoyltrifiuoroacetone (TTA)in decahydro-naphthalene (decalin).
The simultaneous radiochemical separation of Zr
and Hf from a solution of an Au target irradiated byan N-14 ion beam has been developed. It is based on
the extraction of Zr and Hf with TTA in decalin fromthe multitracer solution containing carrier free Zr and
Hf, and the extraction of other elements from 2 M of
HCI and HN0 3 . The reversed phase extraction of Zr
and Hf is also developed by using aqueous EDTA solution at pH range of 8.5-10. Various parameters, suchas effects of pH, HCI and HN0 3 concentration, equilibration time, concentration of TTA, various solvents,
and coextraction of other elements on the extractionof Zr and Hf, have been optimized.
Separation of the multitracer from an Au target irradiated by an N-14 ion beam is already described ina previous report. 3 ) A carrier-free multitracer solution
in an aqueous phase was used in this study.
Typically, 1 ml of a carrier-free multitracer solution
was taken in a beaker containing 8.5 mi of 2 M HCI or
HN0 3 and 0.5 mi of H 2 0 2 , the contents were warmed
slightly with stirring. After cooling, the contents weretransferred to a separating funnel containing 10 ml of
0.2 M TTA in decalin, and the funnel was shaken forabout 15 minutes using a mechanical shaker. Afterequilibration, the separated organic phase was transferred to another separating funnel and 5 ml of a buffer
solution of pH range 8.5- 10 and 5 ml of 0.20 M aqueous
EDTA solution were added to it. The solutions wereshaken for about 5 min for back extraction of Zr and
Hf. All activities were counted on an HPGe detector
and 4 k MCA.
The effect of HCI and HN0 3 concentration on percent extraction of Zr and Hf was studied. It was observed that the extraction behaviour of both the elements is almost the same up to 5 M concentration.

Almost complete extraction occurred at 2 M HCI and
HN0 3 . The percent extraction was decreased as theacid concentration increased. At higher HCI concentrations, complex formation of Zr and Hf with chloride ions in the aqueous phase lowers the extraction
efficiency. Also the optimum pH for the maximum
extraction of Zr and Hf was found to be 3 and thenthe extraction efficiency decreased at higher pH, which
may be due to formation of hydroxides.
Several aqueous media were prepared in 2 M Hel
and HN0 3 acid and extraction was carried out with
TTA and various organic solvents. We found that the
decalin gives the highest extraction yield of Zr and Hfamongst the other 14 solvents studied. Extraction wasquantitative only with decalin and moderate with xylene. Other solvents were also effective but extraction
was below 90% for both the elements. Also it was observed that the percent extraction of Zr and Hf is more
effective in HCI medium than in HN0 3 medium in all
the solvents.
The reagent concentration was also important in Zr
and Hf extraction study. At lower concentrations of
the reagent, the percent extraction is less and as theconcentration of the reagent increased from 0.05 to 0.2
M the percent extraction inceased sharply and then it
remained constant for both the elements.
In the coextraction study, Rb, Sr, Nb and Sc are coextracted but coextraction of Sr and. Rb is about 3%
and 5% respectively. However, the co extraction of Nb
is about 11% and that of Sc is about 15%. The otherelements present in the multitracer are not coextracted
at all. Therefore, except Sc and Nb there is no serious
coextraction. The carrier-free Zr and Hf were back extracted using aqueous EDTA at pH 8.5- 10 which lowers the coextraction of interfering elements by about
2-5%, and back extracted carrier-free Zr and Hf canbe used for a further study of animal and plants.
References
1) F. L. Moore: Anal. Chern., 26 , 997 (1956).
2) R. E. Connick and W. H. McVey: J. Am. Chern. Soc.,
71, 3182 (1949).
3) R. G. Weginwar et al.: This report, p. 138.

139

RIKEN Accel. Prog. Rep. 29 (1996)

Metabolism of Trace Elements in Marine Algae:
A Study Using the Multitracer
R. G. Weginwar, M. Katayama, S. Ambe, S. Enomoto, B. Liu, and F. Ambe
The behaviour of various trace elements in marine
algae is being studied by the multitracer technique. In
recent years, pollution in marine environment has become a serious problem for human lives. These problems are mainly due to industrial waste as well as wastefrom human life. Another problem is the radioisotopes
emmitted from nuclear testings and accidentally leaked
from nuclear plants into the ocean. These wastes
may influence human bodies possibly through the foodchains. Therefore, the mechanism of the incorporationof trace elements from sea water into plants and animals is important for our own health.
In this study, the incorporation of various trace elements in the marine algae (Chactoceros sp.) is experimentally investigated using a radioactive multitracer.
As the first step, the relative amount of elements incorporated in the marine algae is determined.
For the production of a multitracer, an Au target
irradiated with N-14 ion beam at the RIKEN Ring
Cyclotron was dissolved in aqua regia and Au(III) was
finally removed from 3 M Hel solution by extraction
with ethyl acetate, and a carrier-free multitracer solution in artificial sea water was prepared.
The algae were grown in a normal medium 1 ) under
2700 lux light from fluorescent lamps at 26°C on a rotary shaker for several weeks and then transferred toa new medium without phosphate salts. Four ml ofa culture solution was transferred to a sterilized tube
and centrifuged at 2000 rpm for about 5 min. and theaqueous phase was discarded. The cells left in the tube
were mixed with 4 ml artificial sea water and 0.5 mlof the multitracer solution. After specific time intervals (5, 10, 20, 50 min.), 1 ml of the culture solution

140

was withdrawn and washed with 1 ml of sea water(3 times); finally the cell fraction and all the washingfractions were collected in separate tubes and counted
on an HPGe detector and 4k MCA. Some preliminary
results of incorporated elements in the cells are shownin Fig. 1. From Fig. 1, it is evident that the rate ofincorporation of Se, Rb, As , Co , Fe, and Zn is quite
similar. A further work is being carried out on incorporation as well as excretion of trace elements in marine
algae in order to underst and the detailed mechanismof incorporation of these elements.

1~,------------------------------,-{]--Se~Rb,a 10000~--o--As

til

C--I:r--Co= 1000Q

CJ~Fe---?IE-- Zn
100~~--.---~r---~-----r----'-~

o

10

20

30

40

50

Time of Incorporation (min)Fig. 1. Incorporation of carrier-free radio nuclides in marine alga cells.

References
1) M. Katayama, Y. Sugawa-Katayama, and A. A. Benson:
Appl. Organomet. Chern. , 4 , 213 (1994).

RIKEN Accel. Prog. Rep. 29 (1996)

Biodistribution of Gold Complexes in MiceR. G. Weginwar, S. Enomoto, B. Liu, S. Ambe, and F. Ambe
Many gold compounds are highly toxic to animals,
especially chloroauric acid and its salts, largely because of their oxidising ability. 1) Gold and its compounds have a long history of medical applications.
A few gold compounds have been used very successfully, in the treatment of rheumatoid arthritis, as anantitumor agent, etc. Very little is known about themechanism in which the gold containing drugs act.
The purpose of this paper is to study the biodistribution of Au (III) ions and Au (III) complexes in mice.
It is thought that gold(III) would be more suitable
than gold(I) for certain purposes. Gold(III) is isoelectronic with platinum(II), and forms similar square planar complexes. However, many gold(III) complexes arereadily reduced to gold(I) or gold metal, which meansthat they would never reach the desired site and would
instead be toxic. It is necessary to choose the ligands
very carefully to prevent this.
In the present study, the uptake and distribution ofradioactive gold(III) ions and gold(III) complexes invarious tissues, organs and blood of normal mice were
examined to clarify the behavior and role of gold(III)in animals.
A piece of gold foil was irradiated with 135
MeV /nucleon C-12 ion beam at RIKEN Ring Cyclotron. After cooling, the foil was dissolved in aqua regia and this solution was evaporated to dryness under
reduced pressure and the residue was dissolved in 3M
HCl. An appropriate amount of the solution was taken
in a funnel containing 5 cm 3 of 3M Hel was extractedwith an equal amount of ethyl acetate. After equilibration, the yellow-colored organic phase containing
Au tracers with carrier was separated out. Then theorganic phase was back extracted with an equal volumeof 0.1 M, 2-amino-2-hydroxymethyl-1,3-propandiol in
an aqueous medium. Similarly, the organic phase wasback extracted with 0.1 M sodium diethyl dithio carbamate in parallel. Also, a Au(III) tracer with carrier
was prepared in saline water. These solutions were injected i.p. (12 mg Au(III) / kg of mice) to normal
ddy mice which were 10 weeks old. The mice were sacrificed after 3, 24, 48 hrs and the tissues, organs andblood were weighed and the activities were determinedby gamma-ray spectrometry. The results are given inpercentage of i.p. dose and weight of tissues, organs
and blood (Uptake rate %/g).
Figure 1 shows the distribution of the amino complex of Au(III) in mice. It is seen from Fig. 1 thatthe uptake in kidney, testes, liver, blood and spleen ishigh. In case of kidney, the uptake rate of the amino
complex is about 4 times higher at 48 hrs after injection than that at 3 hrs after injection. While in case of
muscle, uptake is almost twice at 48 hrs than that at
3 hrs after injection, it is reversed in case of blood andtestes, namely, accumulation of the complex is about
5 and 3 times more at 3 hrs than at 48 hrs after injection, respectively. In case of liver, spleen and intestine,
uptake is almost comparable in both the cases.
The measurement has been finished and the analysis is now being carried out for the diethyl dithiocarbamate complex and the tracer with no complexing agent
in saline water at 3, 24, and 48 hrs after injection.
KIDNEYINTESTINE
LUNG
rJ'j

~

MUSCLE

~

BONE

~

BRAIN

rJ'j
rJ'j

~

D

3 hrdata•

48hrdata

TESTISELIVERBLOODSPLEEN
0

2.5

5

7.5

10

12.5

Uptake rate (%/g)

Fig. 1. Uptake rate (%/g) 2-amino-2-hydroxymethyl1,3-propandiol complex of Au (III) in various tissues, organs and blood of normal mice.

References
1) R. V. Parish and S. M. Cotrill: Gold. Bull., 20, 3 (1987).

141

RIKEN Accel. Prog. Rep. 29 (1996).

Metabolic and Biochemical Studies of Trace Elements In
Zinc-Deficient Rats (1) Biochemical Properties of
the Platinum-Group Elements
S. Enomoto, M. Yanaga, R. Hirunuma, K. Endo, S. Ambe, and F. Ambe
A new multitracer technique developed by us canbe used to analyze the metabolism and behavior ofa number of elements in living bodies simultaneously.
We were able to reproduce a wide range of results on
the behavior of various elements obtained in individual
experiments performed by other reserchers in a single
run using this technique. At the same time, we could
reveal the behavior and interaction of many other traceelements which other researchers have not included intheir analysis.
Zinc is the second most abundant transition element
in animals, following iron and plays an important rolein many metabolic processes in living organisms.
In the present study, the uptake and distribution ofradioactive isotopes in various tissues, organs and body
fluids of normal and zinc-deficient rats were examinedby means of the multitracer technique to clarify the
behavior and roles of various trace elements. 1)
A multitracer was prepared from a gold target irradiated with a 135 MeV/nucleon heavy ion beam.
A saline solution containing the multitracer was prepared and was injected intravenously to normal andzinc deficient male Wistar rats. The chemical forms oftracers on administration were assumed to be Sc 3 +V0 2+ , Mn 2 + , C0 2 + , Zn 2 + , Rb+ , Sr 2 + , y 3 + , Ce 3 +',Eu 3 +, Gd 3 + , Tm3 + , Yb3 + , Lu 3 +, ReO;, [IrC16 ]2-,and [PtC1 6]2-.
The amount of zinc accumulated in the skin, testicles, and bones of the zinc-deficient rats was smaller
than that accumulated in the same tissues of the normal rats; however, the amount of zinc accumulated inother tissues including the blood was larger in the former than in the latter rats. Bone and skin are organs
in which zinc is known to store. The results of neutron
activation analysis suggested a decrease in the amountof zinc accumulated in these organs in zinc-deficient
rats compared with normal one (unpublished). The
amount of zinc accumulated in the testicles was also
found to be smaller in zinc-deficient ratsthan in normal
one. As a major symptom of zinc deficiency, a decrease
in reproductive ability is reported. Therefore, our results regarding zinc accumulation in zinc-deficient rats
may indicate decrease in reproductive ability.
Figure 1 shows the uptake of Pt and Ir in normal andzinc-deficient rats. The amount of Pt accumulated in
the kidneys and plasma was significantly larger thanthat of Ir. However, when we administrated Pt and Ir
to zinc-deficient rats, the amount of Ir accumulated in
kidneys and plasma was larger than that of Pt by afactor of about 2- 5.
142

(a) 5

(b) 1

4

0.75

~
OJ

..:Ii

0.5

co

C.

;J

0.25
0

0
NormalZn Der.

NormalZn Der.

Fig. 1. Uptake (%) of the platinum group elements in normal and zinc-deficient rats. (a) kidneys and (b) plasma.

In general, Pt and Ir are classified into a group of elements exhibiting similar behavior in normal rats (theplatinum group). The present results on Pt and Ir in
normal rats agree well with the previous reports.
The chemical forms of Pt and Ir in the dosage solution and the body fluids were [PtCI 6 ]2- and [IrCI 6 j2-,
respectively. However, the distributions of Pt and Ir
in zinc-deficient rats are quite different from those innormal rats. Accordingly, the differences in the rate of
uptake of these elements in zinc-deficient rats are regarded to be a result of differences in binding proteinsor protein affinity.
Therefore, we carried out SDS-PAGE for plasma of
normal and zinc-deficient rats. Pt-binding proteins innormal rats were found also to bind to Ir, but to havemuch greater affinity for Pt. On the other hand, inthe zinc-deficient state, the Pt-binding affinity of a Ptbinding protein was less, and the Ir- binding affinity ofa Pt-binding protein increased. Proteins which specifically bind to Ir exist in the plasma. This proteins
which have a specific Ir-binding fraction have a molecular weight of approximately 66 kDa. However, wemust examine this protein in more detail. The metallothionein activities in the kidneys and skeletal muscleof zinc-deficient rats were increased approximately 32
and 42%, respectively, by Ir. In other words, in thezinc-deficient state, Ir induced metallothionein activities which were stronger than those induced by Pt.
These results suggest that zinc deficiency contributes to conformational changes or affinity changesof transport proteins or enzymes which are involved in
the uptake of Pt and Ir.

References
1) S. Enomoto et al.: J. Radioanal. Nucl. Chern., in press.

RIKEN Accel. Prog. Rep. 29 (1996)

Metabolic and Biochemical Studies of Trace Elements in
Zinc-Deficient Rats (2) Ionic Radius Dependenceof Uptake of Rare-Earth Elements
S. Enomoto, M. Yanaga, R. Hirunuma, K. Endo, S. Ambe, and F. Ambe
We have developed a multitracer technique whichenables simultaneous analysis of the behavior of a number of elements in various chemical and biological systems. Significant features of the technique are as follows. (1) The broadness of the elements covered. (2)High efficiency. (3) The behavior of a number of elements can be compared under identical experimental
conditions. (4) Serendipity. (5) Carrier-free and often
salt-free radioisotopes can be used. (6) Many isotopes
which are not readily available as single tracers areincluded.
In the present study, the uptake and distributionof rare-earth elements (REE) in various tissues, organs and body fluids of normal and zinc-deficient
rats were examined by means of the multitracer technique to clarify the behavior and role of different traceelements. 1)
The amount of REE taken up in various tissues, suchas liver and kidney, was found to be correlated with theionic radius of the REE. Figure 1 shows the dependenceof the amount of uptake in liver (Fig. 1 (a)) and bone(Fig. l(b)) on the REE ionic radius. The amount of
uptake of "light" REE (Ce and Eu) in liver increased
with increasing ionic radius; however, that of "heavy"REE (Cd , Tb , Y , Tm, Yb , and Lu) in liver showed nomarked tendencvy to ward change with change in ionicradius. These results suggest that the uptake of light
REE, whose ionic radii are similar to that of calcium,is interrelated with the calcium transport proteins in
the cytoplasmic membrane.
Therefore, we measured the binding activity of thepurified Ca channels of Ce, Eu, Y , Yb, and Lu
with primary-culture hepatic cells. The binding activity was found to decrease in the following order:
Ce> Ca > Eu » > Y > Yb = Lu. We also measured
the binding activities of Ca 2 +-ATPase and REE andcalculated the binding ratio of REE vs. calcium toCa2 + -ATPase. The binding ratios of Ca2 +-ATPase
for Ce and Eu were similar to that of Ca. However,
the affinities of Ca 2 +-ATPase for Y , Yb, and Lu were
smaller to that of Ca. The above results of the l;>inding activity measurements of both proteins indicatethat the membrane transport of the light REE involves
transport proteins such as various Ca channels andCa2 +-ATPase and that cytoplasmic accumulation requires the precence of Ca2 +-ATPase in the endplasmic
reticulum.
In contrast, the amount of uptake of REE in bone
was different from that in other tissues (Fig. l(b)). The
heavy REE were accumulated in bone to a greater ex-

tent than the light REE. The amount of uptake of light
REE decreased with increasing ionic radius. These results indicate that heavy REE are adsorbed on hydroxyapatite that reacts with enzymes such as alkaline
phosphatase and that light REE are non-specificallyadsorbed on connective tissue on bone surface.
As shown in Fig. l(a) and (b), the distributions ofvarious REE exhibited similar behavior in normal andzinc-deficient rats. These results indicate that the calcium transport system dose not involve Zn-regulated
proteins.
(a)~.-------------------------~

30

i
QI

..:.:

--0-

Nonnal Rats--0--

Zn DeOcient Rats

20

~

Q.
~

10

0
0.85

0.9

0.95

1.05

0.85

0.9

0.95

1.05

(b)
15

i
QI

10

..:.:
~

Q.
~

5

Ionic radius ( A)

Fig. 1. Dependence of the amount of uptake (%) in liver(a) and bone (b) on ionic radii.

The levels of various biotrace elements can reflectvarious disease states. In certain diseases, some elements become a reliable source of information for diagnosis.
In conclusion, when we applied to a given biologicalsystem, the multitracer technique is a powerful tool to
obtain information on the behavior of trace elements
and the multidimensional interdependence of various
elements in various tissues, organs and body fluids.

References
1) S. Enomoto et al.: J. Radioanal. Nucl. Chern., in press.

143

RIKEN Accel. Prog. Rep. 29 (1996)

In Vivo Behavior of Various Rare-Earth Elements in Lipogenous
Diabetes Model Mice by Using the Multitracer Technique
S. Enomoto, B. Liu, R. G. Weginwar, R. Amano, S. Ambe, and F. Ambe
Radioactive-tracer method is a useful technique inscience, technology, medicine and other various fields.
Recently, a new 'multitracer technique' has been developed at RIKEN. A multitracer solution contains a
number of radioactive isotopes employed for tracing.
The multitracer enables us to determine the characteristic behavior of various elements under an identical condition. Diabetes is one of the most generaland intractable diseases of adult people, which has a
lot of complications. In the present study, the multitracer technique was applied to an investigation of
the in vivo behavior of trace elements in lipogenous
diabetes model mice in comparison with normal mice.
A gold foil was irradiated with C-12, N-14 or 016 beam of 135 MeV Inucleon from RIKEN Ring Cyclotron. The Au foil was dissolved in aqua regia. After
Au ions were removed by extraction with ethyl acetate,
the rare-earth elements (REE) were extracted from a
HCI-multitracer solution by di(2-ethylhexyl) phosphoric acid solution in heptane and were back-extractedwith Hel. l ) The REE multitracer solution was kept todryness and dissolved in a saline solution before experiments. The solution was injected intraperitoneallyto diabetes model (KKAy ITa Jcl) and normal mice(male). The mice were sacrificed several hours after
injection. The tissues, organs and body fluids were
weighed and their radioactivities were determined by,-ray spectrometry. Identification and determinationof isotopes were done on the basis of their energies,
half-lives and peak areas. The results are given in percentage of intraperitoneally injected dose of tissues, organs and body fluids (uptake %).2)
From the analysis of ,-ray spectra, distributions ofY, Ce, Eu, Gd, Vb, and Lu were determined. Whenintraperitoneally injected, various REE exhibited quite
different distributions in both normal and diabetes
mellitus model mice. The uptake of REE in the livers of both kinds of mice shown in Fig. 1 was correlated with changes in the ionic radius of REE. The
uptake of "light" REE increased with increasing ionicradius; however, there was no marked tendency in thatof "heavy" REE. The quantities of accumulation of
REE in diabetes mice liver were larger than that ofnormal mice by a factor of about 2- 5. Triglycerideand blood sugar concentrations in blood serum of diabetes mice were found to be relatively higher thanthose of normal mice as shown in Table 1. The resultsof pathologic diagnosis in a diabetes mouse liver bya microscope revealed hepatic steatosis. The uptake

144

60

(a) Liver

--0--

~ 40

~-

CI.I

..:.t:

1:':1

Q.
;:;l

20

0

0

1.05

0.95

0.9

0.85

0.8

15
(b) Kidney

~

10

TT

O~~ T

11

CI.I

T

1

Eu

Ce

Gd

..:.t:

1:':1

Q.

;:;l

5

O+-------~------~----~------~------~
1.05
0.95
0.9
0.8
0.85

Ionic radius (A)Fig. 1. Uptake dependence on ionic radii in liver (a) andkidney (b).

Table 1. Biochemical data of diabetes model and normal
mice serum.
Diabetes model

Normal (ddY)

Blood sugar value 250.3±1.6 mg/dl 121.4±16.9 mg/dl(GLK/G6PDH)
Triglyceride242.8±14.3 mg/dl 95.1±22.7 mg/dlof the REE in a normal mouse kidney, is correlatedwith changes in the ionic radius of the REE. However,the uptakes in diabetes mice do not depend on the
REE ionic radii. The results of pathologic diagnosis ina diabetes mouse kidney revealed diabetic nephrosclerosis. Mesangial cells become the vitreous structuresand show the tuberous lesion. These results indicatedthat REE are accumulated in adipose tissue of liver inthe case of diabetes mice and that REE are stored inrenal corpuscles.
References
1) B. Liu et al.: Bull. Chem. Soc. lpn., in press.
2) S. Enomoto et al.: l. Inorg. Biochem., 59, 353 (1995).

RIKEN Accel. Prog. Rep. 29 (1996)

Metabolic Studies of Various Trace Elements in
Acute Alcoholic MiceS. Enomoto, B. Liu, R. G. Weginwar, R. Amano, M. Yanaga, S. Ambe, and F. Ambe
Bio-trace elements are concerned with many physiological functions and their concentration changes reflect various kinds of diseases. It has also become clearthat many of them are important in maintenance of invivo metabolic functions.
Alcoholics is illness characterized by insufficient nutrition, dyspepsia and abnormal absorption of nutrients. Alcoholics is easy to produce abnormality inmetabolism of bio-trace elements merging with liver orpancreas obstruction. Ingested alcohol is metabolited
in the liver. When alcohol is taken by excess, alcohol
metabolism in the liver is selectively accelerated and,
therefore, whole metabolism in the liver system suffers
a drastic disorder.
Principally, alcohol ingested in the liver is dehydrogenated by alcohol dehydrogenase (ADH) in hepatic
cell and becomes acetaldehyde. Furthermore, this acetaldehyde receives dehydrogenation by aldehyde dehydrogenase and becomes acetic acid. This acetic acidis used in synthesis of acetyl CoA, and it is utilized by
the TCA cycle.
When alcohol is taken in surplus, the creation of
NADH increases. Therefore, the NADH/NAD ratio
becomes large, and this co-enzymatic system in hepatic cells inclines to the reduction type. On this account, the concerned reaction system in hepatic cells
goes to a direction of restoring this conditions. That
is to say, metabolism in the liver system is led to a
general change.
Besides the ADH enzymatic system, there are three
non-alcohol dehydrogenase systems (non-ADH) as follows; microsome-ethanol enzymatic system, NADPHoxidase-catalase system and xanthine oxidase-catalasesystem. These metabolism systems usually take approximately 25% of all alcohol metabolism. The continuous dosage of alcohol activates non-ADH systems.
As a result , non-ADH systems be come to share around
50% in quantity of all the alcohol metabolism. The
liver is the leading organ for metabolism of chemicals including trace elements and drugs besides alcohol.
The dramatic change of liver function by alcohol described above gives big influence to the metabolism.
As a characteristic of biochemical changes of the alcoholics liver obstruction, hepato-secretary proteins suchas albumin and transferrin accumulate in inner hepatic

cells. Albumin and transferrin are important proteinsparticipating in the first reception and transportation
process of trace elements. Therefore, it can be predicted that alcoholics give large influence on the biobehavior of trace elements, too.
In the literature, certain influence of alcohol on themetabolism of copper, selenium, iron, and magnesium
is described . However, the nutritional influence given
to alcohol metabolism of other trace elements is not yet
studied at all. Therefore, it was assumed that detailed
investigation is required.
In this work, we carried out studies on the metabolic
abnormality of trace elements in acute alcoholics, withthe multitracer technique.
Three ddY mice were treated intraperitoneally withalcohol at 3 hr before and at 3, 11, 19, 27, 35, 43, 51, 59,
67 and 71 hrs after the multitracer solution injection
described below. Each mice received 0.025 ml/g bodyweight of 25 (V /V)% alcohol each time. The injection
schedule is shown in detail in Table 1. A multitracer
Table 1. The experimental schedule of ethanol (E), themultitracer solution (M) injection, and sacrifice (8).
-30

3 11 19 27 35 43 51 59 67 71 hr.

E
E
E
E

M
M
M
M

8
E
E
E

group
(a)
(b)
(c)
(d)

E
E
E

E
E
E

8
E
E

E
E

E
E

8
E

E

E

8

Ethanol of concentration 0.025 mljg (25% Ethanol
jsaline solution) is intraperitoneally injected. The multit racer saline solution (0.1 mlj each mice) is intraperitoneally injected.

was prepared from a silver target irradiated with a 135
MeV / nucleon heavy ion beam, and 11 radioisotopes
served as tracers. A saline solution containing the multitracer was prepared and injected intraperitoneally tothe above acute alcoholic mice. After sacrificed, themice were subjected to the examination of the uptake
and distribution of radioactive tracers in their variousorgans. The measurements have been finished and thedata analysis is now being carried out. Detailed data
and discussion will be reported later.

145

RIKEN Accel. Prog. Rep. 29 (1996)

Research in Metabolic Physiology on Space Field byUsing the Multitracer Technique - A Proposal
S. Enomoto, H. Maeda, S. Ambe, and F. Ambe
The creatures on the earth fit themselves to various kinds of environment, and evolve and prosper. In
recent years, it has been realized that mankind utilizes universal space. Information concerning changesof homeostasis of a creature in universal space is stillmuch limited. Detailed physiological studies on thisproblem are a pressing need. Bio-trace elements canbe an index reflecting various kinds of diseases. In certain diseases, some elements become a reliable sourceof information for diagnosis. The multitracer technique, a tracer technique developed by us , can analyze metabolism and behavior of different elements inthe living bodies simultaneously. We proved that thismethod is a powerful tool to obtain information on the
behavior of bio-trace elements. 1 ,2)In this article, we describe the usefulness of the multitracer technique in the studies of trace elements inliving bodies and discuss possibility of its application
to metabolic physiology in universal space environments such as low or zero gravity, low oxygen concentration, radioactive rays exposure and low atmosphericpressure. 3 )The multitracer method excels in following points
in comparison to the current method. (1) The broadness of the elements covered. At present , fifty-two elements have been traced with the technique. Information about around 10 from 50 kinds of elements isprovided in a single experiment. (2) Information iscompletely provided under the same condition. Because of differences of sample and individual are large
in the living body, it is extremely important in eachelemental mutual comparison and interacting studies
that data about many elements are provided under
the completely same conditions. (3) When we utilize ausual radioisotope as a tracer, a very small amount of
it is sufficient. However, in the case of (n, ,) reaction,146

the quantity of a stable isotope contained in the radioisotope product cannot be ignored. On the contrary, each element ina multitracer solution is carrierfree and therefore consideration of its toxicity is completely needless. A quantity of one element is approximately pico gram order or less. (4) Because we
can measure the behavior of many elements simultaneously, there is the possibility that we can discover a
new fact about the trace elemental behavior and rolethat is not intended. (5) We can get various kinds ofelements in the periodic table as a tracer by selecting
a target. (6) The multitracer contains a precious radioisotope even as a single tracer (Mg-28 , Ca-47 etc.) .
From these points of view , the multitracer techniqueis quite suitable for the space experiment with only alimited chance and period. For instance, at our bone,
the obstruction of calcium absorption occurs in a low
gravity space environment. Besides this , a change ofvarious kinds of physiological situations that are notclear occurs, too. It is considered in this connectionthat we can make the behavior of bio-trace elements
clear, in particular dynamics of bone seeking elements
by application of a multitracer. Undoubtedly, these experiments will give basic and useful information about
physiology and biochemistry of the creatures to use theuniversal space in future.
References
1) S. Enomoto, M. Yanaga, R. Hirunuma, K. Endo, S.
Ambe, and F. Ambe: 1. Radioanal. Nucl. Chem. , inpress.
2) B. Liu, S. Ambe, S. Enomoto, and F. Ambe: 1. Radioanal. Nucl. Chem. , Lett., 201, 273 (1995).
3) S. Enomoto, S. Ambe , and F. Ambe: Proc. of 12th
Space Utilization Symp ., 12 , 91 (1995).

RIKEN Accel. Prog. Rep. 29 (1996)

Preparation of a Multitracer from Heavy-Ion Irradiated Tin by
Heating under Reduced Pressure
M. Iwamoto, H. Maeda, and F. Ambe
A separation method of multitracers by heating under reduced pressure from a heavy-ion irradiated target
was established. 1-3) We previously chose gold, silver,
and copper as targets, and in this report an experiment on tin is described. Tin has a very low vapor
pressure in spite of its lower melting point (231.8 °C)
than ordinary metals.
A tin target was irradiated with a 135 MeV/nucleon

14N beam or 12C beam. After irradiation, the target
was heated up to a fixed temperature under a reducedpressure in a quartz tube for 1 hour. A sample washeated up to 600°C and after that up to 800 °c. Twoother samples were heated up to 1000 and 1100 °c,
respectively. It was found that some kinds of nuclides
W8re driven out of the target and trapped on a cold
part of the tube. They were easily dissolved by warm

Table 1. Activity of the nuclides.
Heating temperature
activity
Be-7
Sc-47
Cr-51
Mn-54
Cu-67
Zu-65
As-77
Se-75
Rb-83
Rb-84
Y-88
Zr-88
Ag-105
Ag-106m
Cd-109In-Ill
In-114m
Sn-117m
Sb-120
Te-119m
Te-121
Te-121m

600 ° C(cps)

800 ° C
(cps)
0.705
0.113

1000 ° C
(cps)
0.386
0.01320.00820.0246

0.072

5.67

0.108
0.0404
0.37
0.719
0.298

0.404
0.164
30
7.89
0.303
0.022
0.097

0.09560.00420.232
0.54
0.15470.00240.00820.0054

0.723
1.352
0.696

0.883
1.147
0.618
3.605

0.09160.006
0.01320.07290.133
0.157

0.00140.0181
0.02170.099

6M HCI. Heating time and dissolving time were thesame. Table 1 shows the amount of activity of somenuclides with comparatively long halflives. Some elements (Zn, As, Se, Rb, Cd, In) were expelled fromthe target even at a low temperature and some otherelements (Sc, Ag, Sb, Te) only at a high temperature.

1100°C(cps)
0.477
0.20340.20870.59330.22080.03361.51560.51070.16690.00270.18751.76290.28880.54812.52282.955
0.47710.155
0.06620.1271
0.191

References
1) M. Iwamoto et al.: RIKEN Accel. Prog. Rep., 24, 72(1990).
2) M. Iwamoto et al.: ibid, 25, 97 (1991).
3) M. Iwamoto et al.: ibid, 26 , 85 (1992).

147

RIKEN Accel. Prog. Rep. 29 (1996)

Time Dependence of Distribution of Trace Elements in Rats Using
the Multitracer Technique
K. Endo, R. Hirunuma, M. Yanaga, M. Tozawa,* S. Enomoto, S. Ambe, and F. Ambe
Previously, the uptake and distribution of radioactive isotopes in various tissues, organs, and body fluids of rats were examined by means of the multitracer technique. 1,2) The present study aimed to examine the time dependence of tissue distributions ofradioactive isotopes for a time range of one to six days.
The experimental procedures are the same as reported
previously. 2)
The tissue distributions of radioisotopes of Rb, Mn,
Co, Zn, As, Rb, Pt, and Ir were measured in the time
range of one to six days after oral administration. The
results on Rb , Zn, Co, and As are described in thefollowing. Figure 1 shows the results on the tissue

brain
liver
kidney b~~~':';":':':'''''''
skeletal muscle~'-'-'-'-'-'-'-'-'-"

bone
spleentesticles ~~~~
blood

o Rb

intestine

o

0.25
0.5
0.75
uptake rate (%/g)

Fig. 1. Tissue distribution of rubidium in rats 3 days afteradministration.
distribution of Rb expressed in % dose/ g for each tissue three days after administration. The data represent average values of three rats. Rb was distributedin every tissue and high concentrations (% dose/g) of
it were found in liver (0.58), spleen (0.48), and testicles (0.45), and low concentrations in intestine (0.18),
blood (0.18), and bone (0.16). Figure 2 shows the timedependence of Rb concentrations for eight tissues andblood. A general trend was found that the tissue distri0
0

~

-

"
fJ

~
~

'6

0

~
~

Rb

0
0

~

8

~ 0.1

g
l::,
0

¥

'"'

QJ

..::.:

...

0

Brain

0

Liver

t::.

Kidney"Skeletal muscle

0

Bone

0

Spleen<)Testicles

\l

Blood

~

Q.

;:J

0.01
0

2

3 4 5
Time (day)

6

7 'J

Intestine

Fig. 2. Time dependence of rubidium concentration (%dose/g) in eight tissues and blood.
Dept. Chern., The Jikei University School of Medicine

148

butions of Rb decreased in every tissue examined withtime elapsing after administration. Variation range ofthe tissue concentration of Rb one day after administration is estimated to be a factor of 4.4, taking theratio of the highest (0 .88 in liver) to the lowest concentration (0.20 in bone). The variation was found to be
3.7 after six days; namely, it tends to be smaller withtime elapsing after administration. A similar trend
was observed for all the radioactive isotopes used inthis study, although the variation range and the decay rate were characteristic of each radioisotope andtissue.
Zn was also found in all the tissues. The distributionof radioactive Zn one day after administration ranged
from 1.4 in liver to 0.03% dose/g in blood, whereas
it changed to 0.19 in liver and 0.03% dose/g in blood
6 days after administration. The variation of the RI
concentration among the eight tissues and blood wasover a factor of 40 one day after administration, andnarrowed to a factor of 6.3 after six days. It is tobe additionally remarked that the Zn concentration inblood was kept almost constant, i.e., 0.03, 0.04, and
0.03% dose/g for 1, 3 and 6 days after administration.
The time dependence of the concentration of Zn in
brain and testicles was also small. In the case of Co,
high concentrations (% dose/g) were found in kidney(0.69) and liver (0.47), and low concentrations in skeletal muscle (0.006), and testicles (0.02) one day afteradministration. The range of the variation in concentration among the eight tissues and blood was greaterthan two order of magnitude. After six days , the concentration was found to be 0.07% dose/gin kidney,
0.06% dose/g in liver, 0.02% dose/g in skeletal muscle,
and below the detection limit in testicles.
Arsenic showed the following characteristic behavior, i.e., (1) the variation in tissue concentration is thelargest among the elements investigated, and (2) theapparent dwell time in each tissue is long. The uptake
and distribution of As one day after administration was
found to be 6.3% dose/g in blood (the highest) , 'a nd
0.05 in skeletal muscle (the lowest), which corresponds
to a variation range of 126. The % dose/g concentrations were 0.36 in blood and 0.04 in intestine after six
days. The variation range was estimated to be about
one order of magnitude.
References
1) M. Yanaga, S. Enomoto, R. Hirunuma, R. Furuta, K.
Endo, A. Tanaka, S. Ambe, F. Ambe, M. Tozawa, and
F. Ambe: RIKEN Accel. Prog. Rep., 28, 86 (1995).
2) S. Enomoto, M. Yanaga, R. Hirunuma, K. Endo, S.
Ambe, and F. Ambe: ibid., p. 93.

RIKEN Accel. Prog. Rep . 29 (1996)

Multitracer Study on Distribution of Trace Elements in
Vitamin D Overloaded Rats
R. Hirunuma, K. Endo, M. Yanaga, S. Enomoto, B. Liu, S. Ambe, and F. Ambe

It is well-known that Vitamin D (VD) , used for therapy of rickets, osteoporosis and renal failure, affects themetabolism of Ca and P. Recently, it is also used fortherapy of malignant tumor and psoriasis. However,
the effects of VD on the metabolism of various traceelements have scarcely been studied. In the present
study, effects of VD on the behavior of various elements in rats were examined by the multitracer technique, which can be used to determine the behavior ofvarious elements under the same experimental conditions.
A multi tracer solution containing various radioisotopes was prepared from a Ge or Au target irradiatedwith N-14 beam of 135 MeV/nucleon from RIKEN
Ring Cyclotron. A half ml (0.25 J1g as alfacalcidol)of a VD solution was orally administered to each male
Wistar rat every day for a week. A tenth ml of asaline solution containing the multitracer was injected
intravenously in the tail vein of each rat. Then 0.2
ml (0.1 J1g as alfacalcidol) of the VD solution was injected intraperitoneally every day until sacrifice. As
a reference, three normal rats were used. Urine wascollect ed at each proper time after injection. The VDoverloaded and normal rats were sacrificed and the radioactivities of tissues and body fluids were determinedby ,-ray spectrometry. The observed ,-rays were assigned to each radioisotope on the basis of their energies and half-lives. The behavior of Be, Ca, Sc, V , Cr,
Mn, Fe, Co, Ni, Zn, Ga, As , Rb, Sr, Ba, Ir, Pt , Ce,
Eu , and Gd was examined. There were little individual
differences in each group of rats.
In order to examine the physiological condition of
the rats fed with excess VD , the concentrations of alkaline phosphatase, acid phosphatase and Ca in theirplasma were examined. The values of the alkaline
phosphatase for the VD-overloaded and normal rats
were found to be 12±2 Bessey-Lowry Unit (B-L U)
and 17±1 B-L U, respectively. There was little difference between the values of acid phosphatase of
the normal and the VD-overloaded rats. The Caconcentrations were found to be 9.2±0.5 mg/dl and
11.6±0.1 mg/dl, respectively, for the normal and the
VD-overloaded ones. The low concentration of alkaline
phosphatase and the high concentration of Ca for the
VD-overloaded rats prove that they were really overloaded with VD.
The amounts of Be and Sc excreted in urine from the
VD-overloaded rats were much less than those from thenormal rats. The uptake of Be in almost all the tissues of the VD-overloaded rats was smaller than that of
the normal ones. The excretion in feces may have been

increased by the VD-overloading, although the excretion was not measured in the present experiment. It
is thought that the accumulation (and also toxicity) of
Be was restrained by the excess VD. In various tissuesof VD-overloaded rats, a remarkable increase in uptakeof Sc was observed.
Calcium was not detected in the urine of the normal rats, which is explained by reabsorption of theelement into the distal tubules of kidney. However,in the VD-overloaded rats, the excretion rate of Ca
in urine at twelve hours after injection was as high as
9±2%. The Ca concentration was high in blood of
the VD-overloaded rats. The excess Ca was not reabsorbed, but excreted into urine to keep the homeostasisof Ca concentration in blood. The only tissue in which
Ca was detected was bone. In the bone, Ca exists
as hydroxyapatite and is resorbed from the bone byparathyroid hormone and VD, and the uptake in thebone is promoted by calcitonin. The Ca concentrationin the body is kept by the homeostasis. In the bone,
the uptake of Ca decreased slightly in case of the VDoverloaded rats, which could be ascribed to the effects
of VD on the promotion of osteoclast. The uptakeof Be, Sr, and Ba by the VD-overloaded rats also decreased slightly. The metals belonging to alkaline earth
elements behaved similarly to Ca.
In the intestine and testicles, the larger uptake of almost all the elements examined was found by the VDoverloaded rats. Although VD is known to enhance
the absorption of Ca from small intestine, it was foundin the present experiment that VD also raised the absorption of other cations. Testosterone is known toaffect the absorption of divalent cations into testicles.
The present results on the enhancement of the uptake
in testicles of the VD-overloaded rats strongly support
that VD increases the function of testosterone for the
uptake of t race elements in the organ.
The distribution of all the elements was much larger
in the skin of VD-overloaded rats than that of the normal ones. However, if the skin was washed with water,
the difference in the distribution of each element was
not remarkable; i.e. , the distribution of each element in
the skin of the VD-overloaded rats decreased by washing and it was found to be similar to that of the normal
rats. This suggests that the excretion of trace elements
into perspiration through sweat glands is more active
in VD-overloaded rats.
The present study clearly demonstrates that VD also
affects the metabolism of essential elements other than
Ca and P .

149

RIKEN Accel. Prog. Rep. 29 (1996)

Multitracer Study on Distribution of Trace Elements
in Vitamin D Deficient Rats
R. Hirunuma, K. Endo, M. Yanaga, S. Enomoto, B. Liu, S. Ambe, and F. Ambe
Vitamin D (VD) behaves as a hormone of Ca control
functioning to small intestine, bone, kidney and accessory thyroid gland. VD increases the ability of Caabsorption from the small intestine and Ca concentration in blood. VD has a wide effect on the metabolismof Ca in the body, while parathyroid hormone mainly
controls Ca concentration in the body. The effects of
VD on the metabolism of trace elements other than
Ca and P have scarcely been studied. This report describes the application of the multitracer technique tothe study of uptake and the distribution of various elements in VD-deficient rats. A similar study in VDoverloaded rats is described in a separate report. I)
Preparation of the multitracer and injection of its
saline solution to the rats were performed as described
elsewhere. I} Vitamin D deficient rats were fed withmother rats, and the mother being fed with VD deficient diet after giving birth children. As a reference,
three normal rats were used. Urine was collected ateach twelve hours after injection. The rats were sacrificed on four days after injection and the radioactivities
of tissues and body fluids were determined by ,,-ray

spectrometry. Using the multitracer solution obtained
from a Ge-target, the behavior of Be, V, Ca, Cr, Mn,
Fe, Co, Zn, and As was examined.
In order to study the physiological condition of therats fed with VD-deficient food , the concentration ofalkaline phosphatase, acid phosphatase, and Ca intheir plasma was examined. The concentration of alkaline and acid phosphatase was determined based on
the Bessey-Lowry method. The values of the alkaline
phosphatase for the normal and VD deficient rats were
found to be 17±1 Bessey-Lowry Unit (B-L U) and
32±6 B-L U. There was little difference in the valueof acid phosphatase between the normal and the VD
deficient rats (the value of normal rats was 2.9±O.2
B-L U and that of VD deficient rats was 3.1±O.3 B-LU). The Ca concentration in plasma was determinedbased on the OCPC method , and found to be 9.2±O.5
mg/dl (normal rats) and 5.7±O.7 mg/dl (VD deficientrats). The high concentration of alkaline phosphataseand the low concentration of Ca for the VD deficient
rats prove that they were really deficient with YD.
The amounts of various elements in excretion of theTable 1. Excretion rate of various elements after 4 days from injection.
Elements
Be
V
Cr
Mn
Fe
Co
Zn
As

Urine (%)
Normal rats VD deficient rats
23
25
29
32
42
49
0
0
0
0
58
87
0.8
0.7
31
13

VD deficient rats after 4 days from injection are shownin Table 1. The result indicates that there was little difference in distribution for the excretion of theelements between the normal and the VD deficient
rats in general. However, the amounts of As inurine of the VD deficient and normal rats were 13
and 31%, respectively, 4 days after injection. Arsenic was little excreted into feces of both groupsof rats. The uptake of As in the VD deficient andthe normal rats is shown in Fig. 1. The distribution of As in the blood of the VD deficient rats
was estimated to be 9% dose/g whereas that to be
3.2% dose/g in the normal rats. Arsenic is boundto a globin part of hemoglobin in erythrocytes. It isthought that VD affects the behavior of As in the body.

150

Feces (%)
Normal rats VD deficient rats
7
7
11
10
9
8
24
28
8
6
6
9
14
18
1.3
0.9

Blood
Bone
Brain
Intestine
KidneyLiver _ _ _ _ -i
SpleenTesticles
Skeletal muscle
Skin0

o normal rats•2

VO deficient rats

3

9

10

Uptake rate (%/9)

Fig. 1. Distribution of As in the VD deficient and normal
rats on 4 days after injection.

References
1) R. Hirunuma et al.: This report, p . 149.

RIKEN Accel. Prog. Rep. 29 (1996)

Solvent Extraction Behavior of Multitracers by
Di{2-ethylhexyl)phosphoric Acid
Y. Takahashi, Y. Minai, S. Ambe, H. Maeda, F. Ambe, and T. TominagaDi(2-ethylhexyl)phosphoric acid (DEHP) has been
widely employed as a solvent extraction reagent , especially for selective extraction of lanthanides(III).1-4) If
the extraction mechanism by DEHP was understood, it
could be used to determine stability constants of metal
complexes. 5 ,6) The extraction equilibrium of a z-valent
metal ion (Mz+ ) in the aqueous phase, in general, canbe given as follows , DEHP being in a dimeric form: 4)z[(DEHPhJo + [Mz+Ja -t,.. [M((DEHP)2) zJo + z[H+ Ja (1)(0: organic phase; a: aqueous phase) .

The extraction constant (Kex ) is defined as
Kex = ([M((DEHP h h] o[H+]a Z)/([(DEHPh] o[Mz+] a ).

(2)

In this study, the multitracer technique was applied
to reveal the extraction behavior of various metal ions
under the identical experimental conditions.
Multitracers were prepared by irradiating Au andAg targets with 12C or 14 N ions in RIKEN Ring
Cyclotron. 7 ,8) The multitracer solutions were spiked
into the mixture of a DEHP toluene solution and a
HCl0 4-NaCl0 4 aqueous solution (I = 0.02). The concentration of (DEHPh in toluene and pH varied from
0.5 to 0.01 M and from 0.8 to 2.5 , respectively. Aftershaking, both phases were separated to record ,,-ray
spectra by a pure Ge detector. The photopeak intensities of radionuclides of elemetns including Be, Sc, V ,Cr, Mn, Fe, Co, Zn, Ga, As, Se, Rb, Sr, Y , Zr, Tc, Ba,
Ce, Eu, Gd, Tb, Tm, Vb, Lu , Hf, Re, Ir, and Pt were
determined with a routine. The extraction coefficient
D was obtained as the ratio of photopeak intensities ofboth phases after correction for the decay.
In Fig. 1 is shown the dependence of logD on pH andon log[(DEHPh]' respectively, for some ions. Under
the conditions we examined, As, Rb , Tc, and Re were
never extracted, since Rb+ is an alkali metal ion andthe others form oxoanions in the aqueous phase.
As for Be, Sc, V , Cr, Mn , Fe, Co, Zn, Ga, Sr, Y ,Ba, Ce, Eu, Gd, Tb, Tm, Vb, and Lu, each logD was
linearly related to pH and log[(DEHPhl. Since theSo~- + -· Mn
V+-- Sf-e--6- 0$0- - Zn
0Z,
- J( _. GIl

I

I(DEHP) , I =O.SM

,x

0.1

1.2

/0

-<>y
_____ . Ce
Eu

1- s-

. . •• . . Tm
Gd, I-llo- - Yb

pH=1.12

(a)

/

U
pH

2.4

-2

·1.1

·1.2

.0.1

logI(DEHP ) ~Fig. 1. Dependence of distribution coefficient D on pH (a)and log[(DEHPhl (b).

extraction of the tracers will not influence [(DEHPhlo,this allows Eqn. (2) to be converted to
10gD = z pH + z 10g[(DEHPh] + 10gKex .
(3)
The slopes of logD against pH and log[(DEHPhl wereidentical to 2 for alkaline earth metals and 3 for rareearth elements, respectively, as expected from the relations shown in Eqn. (3). The slopes also indicated that
Mn, Co, and Zn were divalent, while Cr, Fe, and Ga
were trivalent under the condition examined. However,the slopes for V changed from 2 at about pH 1 to 1 at
pH> 1.8, suggesting that V0 2+ and V0 2 + were stable
at the respective pH region. 9 ) The logKex obtained byleast squares fitting for Eqn. (3) were listed in Table
1. The values enable us to determine stability constants of the complexes with these ions by the solvent
extraction method. 10 ) Regarding rare earth elements
and alkaline earth metals, logKex decreased with theincrease in ionic radii. This demonstrates the higher
stability of a DEHP complex of the smaller ion in theorganic phase.
Table 1. Extraction constants (Kex) for the elements studied.
Element Charge IogKex Element Charge IogKex Element Charge IogKex
Be
Ln
-1.3
2
1.1
2
Eu
3
0.1
Sc
3
8.8
Ga
3
-0.8
Gd
3
0.3
Cr
-5.8
-4.5
3
Sr
2
3
Tb
0.7
-3.6
Mn
2
3
3
Y
1.6
Tm
2.0
-5.1
Fe
3
3.2
Sa
Yb
2.9
2
3
Co
-5.1
2
3
-loS
lu
3
Ce
3.1

The logD dependence on pH and on log[(DEHPhl
for Zr, Hf, Se, Ir , and Pt was different from that expected from Eqn. (3). This indicates that species notshown in Eqn. (1) were formed for those elements inthe solvent extraction system. For instance, most of Zr
and Hf should have been hydrolyzed in the pH region
we studiedY) Further studies are needed to understandthe extraction behavior of those elements.
References
1) D. F. Peppard et al.: J. Inorg. Nucl. Chern. , 4, 141(1957).
2) K. Kimura: Bull. Chern. Soc. Jpn., 33, 1038 (1960) .
3) K. Kimura: ibid., 34, 63 (1960) .
4) C. F. Baes, Jr.: J. Inorg. Nucl. Chern., 24, 707 (1962).
5) P. M. Shanbhag et al.: ibid., 43, 3319 (1981).
6) Y. Takahashi et al.: J. Radioanal. Nucl. Chern. , Lett.,
186, 129 (1994).
7) S. Ambe et al.: Chern. Lett., 1991, 149.
8) S. Ambe et al.: Anal. Sci. , 7, 317 (1991).
9) C. F. Baes et al.: The Hydrolysis of Cations, Krieger
Rub. Com., Florida (1986).
10) Y. Takahashi et al.: This report, p. 152.

151

RIKEN Accel. Prog. Rep. 29 (1996)

Multitracer Study on Stability Constants of Humate Complexes
with Various Metal Ions
Y. Takahashi, Y. Minai, S. Ambe, H. Maeda, F. Ambe, and T. Tominaga

Humic acid is regarded as an important factor controlling the behavior of metal ions in natural aquifer
system 1 ) due to its high affinity with cations. Humicacid is a naturally-occurring polyacid having a variety
of functional groups in a macromolecule. 2 ) The stability constants of humate complexes reported in literature scatter over a wide range, partly owing to the different experimental methods and complexation models
employed in each work. 3 ) For the mutual comparisonof stabilities of humate complexes with various metal
ions, a particular method and model should be applied.
The multitracer technique has been applied to study
the mutual differences in behavior of a number of elements. We can obtain information on the behaviorof those elements under strictly identical experimental
conditions. Employing the multitracer technique toobtain stability constants of humate complexes withvarious ions, we can eliminate any bias in the determination for their mutual comparisons.
Stability constants were determined by solvent extraction with di(2-ethylhexyl)phosphoric acid (DEHP)
as an extractant. 4 ,5)Stability constants (f3) of the humate complexes withdivalent and trivalent cations are shown in Fig. 1. As awhole, logf3 increased with increasing pH, or degree of
the ionization of humic acid, since increased negative
charge on the humic acid molecule with the increase in
pH enhances the interaction between a metal ion andhumic acid. The slope of logf3 of a divalent ion against
pH was twice as that of pKa, whereas the slope for atrivalent ion was three times larger than that of pKa(Fig. 1). It has been reported that the electrostaticinteraction dominates the metal-humate formation. 6 )This implies that the increment of logf3 or pKa with

10~~~~~~~~20~~~~~~~~(a)-----.- Sc

18

-B

16

- -x - - Ga~~ : ~~

8

14- . .. - pKa

7

12

9

co..

-

~

oCr
- Fe

I

I

~

_ . (7 . - Lu

o

3.5

4

5.5 3.5

cot-3.5 -3.5 0.5

5E-7

Ba

Mn Co

0.5

Zn

Cr

Fe

Ga

Sc

Ln

-0.8

0.5

OH,i=1'
OH-, i=2'

1E-7

1.6 -6.2 -6.4 -3.6 -2.7 -2.0 3.5 4.8

4.4

2.7 -1.5

1E-7

0.4

-5.6 -2.9

8.1

4.3 -14.0

OH-, i=3'

1E-7

-2.2

-11.3

OH-, i=4'
HA

8.3

-7.4

9.0 10.7 4.9 -21 .0

1E-7

6.4 11.4 2.0 ~28.0

1E-7(eq/l 5.0 -0.5 -0.5 -0.5 -1 .0 -1.5 5.0 11.0 10.0 16.0 -6.0

logj3(HA, pH=7)'Order of hydrolYSIS.

012

6.5 6.5

6.5

6

5.5

12

18

17

23

13

-

5

5.5

pH

Fig. 1. The pH dependences of pKa of humic acid andstability constants of humate complexes with divalentions (a) and trivalent (b) (C s = 0.02) .
152

Sr

-

...-.'--"...- ..-- ....
4.5

log([ML]/[M])Ligand [L](M) Be-

10

3.~~~~~~~~~.

Table 1. Ratios of concentration of dissolved complex(ML) to free ion (M) in a land water system at pH =0.02 and I = 0.02 ([L] : concentration of ligands in land
water; log,6(HA, pH = 7): estimated stability constantof humate at pH = 7; hydrolysis constants and stability
constants of carbonates in literature 7) were employed in
the calculation).

..-

~

/'

(b)

increasing pH should be proportional to the charge ofthe cation, as observed. This also explains the higher
stability of a humate complex with a trivalent ion thanthat with a divalent ion.
On the basis of the pH dependence, logf3 at neutral
pH as in natural water was estimated by extrapolation. Assuming the concentration of humic acid,4) the
estimated logf3 values give proportions of the humate
species relative to free ions in the natural water system(Table 1). The proportions of carbonate and hydroxide complexes were also calculated (Table 1). Based onsuch a speciation calculation, the humate complexes
are considered to be predominant in dissolved speciesof rare earth elements in a natural aquifer system atneutral pH. It is notable that a significant fraction ofalkaline earth metals can be dissolved as humate complexes, whereas carbonates are dominant as dissolved
species of divalent transition metal ions such as Mn,
Co, and Zn. About Fe and Ga, hydrolyzed species
dominate their dissolved species in the solution system.

References
1) W. Stumm et al. : Aquatic Chemistry, Wiley, New York(1981).
2) F. J. Stevenson: Humus Chemistry, J. Wiley and Sons,
New York (1982).
3) Y. Minai et al.: Proc. 3rd Int. Symp. Adv . Nucl. Ener .
Res., p. 521 (1991).
4) R. A. Torres et al.: Radiochim. Acta, 35 , 143 (1984).
5) Y. Takahashi et al.: This report, p. 151.
6) T. Miyajima: Ion Exchange and Solvent Extraction,
Marcel Dekker, Inc. , Chap. 12 (1995).
7) A. E. Martell et al.: Critical Stability Constants,
Plenum Press, New York (1982).

RIKEN Accel. Prog. Rep. 29 (1996)

Metabolism of Various Trace Elements in LEe Rats
Leading to Acute Hepatitis
M. Yanaga, S. Enomoto, R. Hirunuma, B. Liu, K. Endo, S. Ambe, M. Tozawa, *H. Nakahara, and F. Ambe
Previously, we reported that the multitracer technique has excellent reliablity and versatility for a comparative study of the uptake and distribution of manydifferent elements in rats.1 ,2) In the present work, thistechnique was applied to an investigation of the uptake
and distribution of trace elements in LEC (Long-Evans
Cinnamon) rats. The LEC rat is one of the two inbred strains selected by coat colour which were isolated
from a closed colony of Long-Evans rats at the Center for Experimental Plants and Animals, Hokkaido
University. 3) The rat spontaneously develops fulminant hepatitis and severe jaundice at 4-6 months ofage and finally develops hepatocellular carcinoma from12 to 18 months after birth.4)
A physiological saline solution of multitracer was obtained from a silver target irradiated with a 14N-ion
beam accelerated by the RIKEN Ring Cyclotron. The
solution was injected intravenously to five 16-weeksold male LEC rats and three 16-weeks-old male SD
rats. Two days after injection, the rats were sacrificed and 8 organs and tissues besides blood corpuscles and plasma were removed. They were brain , liver,kidney, spleen, stomach and intestine, skeletal muscle,
testis and bone. The organs and tissues were placedin polyethylene bottles and weighed, and subjected to')'-ray spectrometry using pure Ge detectors. Identification and determination of nuclides were done on thebasis of their energies, half-lives and peak areas.
Figures 1 and 2 show uptake of various trace elements in liver and kidney, respectively. As shown in
Fig. 1, uptakes of Sc, Mn, Fe and Zn in the liver of LEC
rats were much larger than those of SD rats. Althoughweight of LEC rats and SD rats used in this study was
195- 270 g and 470- 560 g, respectively, the differenceof uptake percent per unit weight of these elements
30

Q)

~

~
o

:::>

10

o
Be Sc

V Mn Fe Co Zn As Se Rb
Elements

Y Zr Ru

Fig. 1. Uptakes of various trace elements in liver of LEC
and SD rats.
Department of Chemistry, The Jikei University School of
Medicine

between LEC rats and SD rats was larger than the
difference of weight of rats. Copper was not detectedin the multitracer solution used in this experiment,
although it is well known that abnormal accumulationof copper is found in the liver of LEC rats and thiscauses the acute hepatitis and hepatoma. 5 ) However,a possibility of abnormal metabolism of Sc and Mn inthe stage examined was first found in the present work.
It seems that the trends of Fe and Zn are in agreementwith the results of PIXE analysis by Matsuda et al. 6)
They reported that Zn and Fe contents in LEC liver
had been very high compared with those in SD liver.
Cobalt, Zn, Se and Y were highly accumulated in thekidney of LEC rats as shown in Fig. 2, although noabnormal accumulation of Sc and Mn in kidney wasobserved in contrast to the case of liver. Iron in kidney
was not determined because of its weak radioactivity.

o
Be Sc

V Mn Co Zn As Se Rb
Elements

Y

Zr

Ru

Fig. 2. Uptakes of various trace elements in kidney of
LEC and SD rats.
Severe jaundice was observed for two of five LEC
rats used, which means that the two LEC rats
had developed acute hepatitis at that time. Suzuki
et al. reported that Zn content in LEC liver decreased suddenly and Fe content increased following
acute hepatitis. 7 ) Although this trend was not observed in the present tracer experiment, the abormal
metabolism of several elements was found in this work.
Further work is planned to elucidate the behaviour of
trace elements in LEC rats.
References
1) M. Yanaga et al.: Appl. Radiat. Isot., in press.
2) S. Enomoto et al.: J. Radioanal. Nucl. Chern. , in press.
3) M. Sasaki et al.: Rat News Lett., 14, 4 (1985).
4) N. Takeichi: CRJ Lett., 4 , 1 (1991).
5) Y. Li et al.: J. Clin. Invest., 87, 1858 (1991).
6) K. Matsuda et al.: NMCC Ann. Rep., 1, 94 (1993).
7) K. Suzuki et al.: Toxicology, 97, 81 (1995).
153

RIKEN Accel. Prog. Rep. 29 (1996)

Studies on the Ion Exchange Adsorption Behavior ofStrongly Acidic Resin Nafion and Its Application
to Analytical Chemistry
A. Sekiguchi, N. Ito, N. Furusato , Y. Saito, K. Kimura, H. Maeda, S. Ambe, and F. Ambe
Radioactive multi tracer solutions in a carrier andsalt-free state, prepared from a gold foil irradiated witha 14N beam of 135 MeV /nucleon l - 5 ) were used for thetitled study in a Nafion-HBr system after being converted to a hydrobromic acid solution. The Nafion-501
resin, manufactured by DuPont, is a perfluorinatedpolymer containing ",,5 mmolj g sulfonic acid groups.
Because of the strong acidity of the resin, a comparisonof its exchange behavior with that of common cationexchange resins attracts much attention.
The resin, commercially available as a cylindricalshape of ca. 1 mm¢ x 3 mm, was crushed with a stamp
mill at liquid nitrogen temperature, passed through a
50-120 mesh screen, and used. Into a small polyethylene bottle, 0.1 ml of the multitracer solution and 2.4 gof the resin were introduced, and the acidity of the system was adjusted to 0.1 , 0.3,0.5, 1,3,5, and 8 M withhydrobromic acid and distilled water, thereby making
the volume of the solution to 10 ml. The contents ofthe bottle were shaken vigorously at 25 0 C with an
8-mode shaker. Time of shaking was 75 hours. After
filtration, ]'-ray spectrometry was carried out for bothphases.
The distribution ratios (Dv) of alkali metals, alkaline
earth metals and rare earth elements were obtained(Fig. 1a). The ratios decrease as hydrobromic acidconcentrations (C) increase and slopes on log Dv-Iog C
plots increase with the valence number of cations. The
behavior described above is the characteristic of the ion
exchange resins. The ion exchange behavior of platinum group metals (Ru, Pt , and Ir) for HBr medium
is somewhat different from that for HCI medium studied previously. In the case of the HCI medium, theslopes on log Dv-Iog C plots were flat . For the HBr
medium, Ru and Ir showed the slopes of - 2 and - 1,
respectively, but Pt did not, as indicated in Fig. lb.
Further, ion exchange separation using a N afion
resin column was carried out with 0.1 M HCI, and 0.3
and 0.5 M HBr eluents. Platinum group metals (Ru,Rh) were first eluted by 0.1 M hydrochloric acid without adsorption, corresponding to their lower Dv values.
Alkaline earth and transition metals were eluted by 0.3
M hydrobromic acid and finally rare earth elements

154

ld "Q
0
1(i
10'

' I • 8a-131

Co

•

0

6-

• •
0

Id E0

.~

c::

e

,9

:l

'0

~

-:

(a)
I

I

lOZ

.D
'~

is

I

• •,

Si

10"
10'2

Ob-83

Ce-139

..,

;>

Q

0

6-

l:>.

101

Do

•

10°
0

•
0

(b)

10,1

Do

10,1

•
0

10°
HBr (M)

Fig. 1. Relationship between distribution ratios and hydrobromic acid concentrations.

were eluted by 0.5 M hydrobromic acid, according tothe order of their Dv values.
References
1) S. Ambe, S. Y . Chen, Y. Ohkubo, Y. Kobayashi , M.
Iwamoto, M. Yanokura, and F. Ambe: RIKEN Accel.
Prog. Rep., 25 , 95 (1991).
2) S. Ambe, S. Y. Chen, Y. Ohkubo, Y . Kobayashi , M.
Iwamoto, M. Yanokura, and F. Ambe: Anal. Sci., 7,
Supp!., 317 (1991).
3) S. Ambe, S. Y . Chen, Y. Ohkubo, Y. Kobayashi , M.
Iwamoto, and F, Ambe: RIKEN A ccel. Prog. Rep., 24,
73 (1990).
4) S. Ambe, S. Y. Chen, Y. Ohkubo, Y. Kobayashi , M.
Iwamoto, M. Yanokura, and F. Ambe: Chem. Lett.,
1991, 149.
5) T. Bamba, H. Harakawa, Y. Saito, K. Kimura, T.
Yaita, S. Shibata, S. Ambe, Y. Ohkubo, M. Iwamoto,
Y. Kobayashi, M. Yanokura, H. Maeda, and F. Ambe:
RIKEN Accel. Prog. Rep., 26, 88 (1992).

RIKEN Accel. Prog. Rep. 29 (1996)

Uptake Behavior of Multitracers in LEe Rats before
Jaundice Development
S. Oishi,* R. Amano , A. Ando,* K. Ishimoto,* M. Naruse,* S. Enomoto, and F. Ambe
Unusual Cu accumulation in the liver of LEC (LongEvans Cinnamon) rats has been known to be involvedin the development of jaundice, hepatic injury and hepatocellular carcinoma. Recently, the biodistributionof other essential trace elements (V, Cr, Mn, Fe, Co,
Zn and Se) in the LEC rats has been of interest to
get an insight into the pat hogenesis of the disease. In
this work, we are st udying the uptake behavior of Sc,
V, Mn, Zn, Se and Rb radioisotopes in the LEC rats
before jaundice development by the use of radioactive
multitracer technique, which was developed at RIKEN.
Male LEC rats at different ages (4, 7 and 11 weeks
after birth) were purchased from Charles River Japan
Inc. The LEC rats were then housed in plastic andsteel cages in Laboratory for Experimental Animals,
Kanazawa University, fed a standard laboratory dietand had free access to drinking water during 1 weekprior to administration. Five LEC rats were used ineach different age.
A no-carrier-added radioactive multitracer solution
was obtained from an Ag (purity: more than 99.99%)
target irradiated with 135 MeV/nucleon N-14 beam accelerated in RIKEN Ring Cyclotron. The preparation
for a multitracer solution from the Ag target was carried out in Radioisotope Center, Kanazawa University,
according to the method of Ambe et al. l - 3 ) More than
35 radioisotopes of 19 elements (Be, Na, Sc, V , Mn , Fe,
Co, Zn, Ga, As, Se, Rb, Sr, Y , Zr, Tc, Ru, Rh and Pd)
can be observed in the solution for injection. Amongthese radioisotopes, 16 nuclides of 13 elements could
be used as the tracers in the LEC rat experiments.
An appropriate amount of the final radioactive multitracer solution was intraperitoneally injected into the
LEC rats. At 48 hr after injection of a radioactive multitracer solution, the LEC rats were killed under ether
anesthesia. After this, brain, pectrales, cardiac muscle, lung, liver, spleen, pancreas , kidney and thymus
were excised. These tissues were weighed immediately
and freeze-dried. The dried samples were measured by
gamma-ray spectromet ry with pure Ge semi-conductor
detectors against an appropriate standard to obtain
the percentage of injected dose per gram of tissue (%dose/g) for different tracers.
In this work, no significant age-dependent changes
in Rb uptake rates were observed in several tissues of
LEC rats. In general, Rb is thought to be analogous topotassium and Rb tracer can penetrate membranes via
potassium ion channels and pump to reach all regions
as a substitute for the similar K ion. It is reasonable
School of Health Sciences, Faculty of Medicine, Kanazawa
University

to assume that no unusual behavior of endogenous K
ions can be observed in the various organs in LEC rats
before jaundice development.
Uptake behavior of Sc, V, Mn, Zn and Se was evaluated as the ratio of Sc/Rb, V /Rb, Mn/Rb, Zn/Rb and
Se/Rb , respectively. Figure l(a) compares easily their
uptake behavior in the liver of LEC rats at 5, 8 and
11 weeks of age. No change in the ratios of V /Rb and
Se/Rb was observed. On the other hand, the ratiosof Mn/Rb and Zn/Rb increased and that of Sc/Rb
decreased with aging before jaundice development of
LEC rats. Recently, Sakurai et al. described that theunusual Cu accumulation was associated with the induction of metallothionein in the liver of the LEC rats
rather than that of superoxide dismutase. 4 ,5) In Fig.
l(a) , the age-dependent uptake of Zn is due to thecorporation of Zn into metallothionein induced by endogenous excess Cu in the liver of LEC rats.
Figure l(b) compares the uptake behavior of Sc, V,
Mn , Zn and Se in the kidney of LEC rats at 5, 8 and
11 weeks of age before jaundice development. No significant change in the ratios of Sc/Rb and Mn/Rb wasobserved in the kidney of LEC rats. On the other hand,
the ratios of V /Rb, Zn/Rb and Se/Rb increased withaging. Especially at 11 weeks old just before jaundicedevelopment of the LEC rats, the uptake behavior of
Se-75 tracer was characteristic in the kidney. We thinkthat Se may playa role in the excess Cu detoxification
function. Further study is required to discuss the Se
function in vivo in detail.
Ra tto6.0. - -- -- -- - , , . . - --

5.0

LIVER

(a)

4.0
3.0

~.:~

-

KIDNEY--- - , .... .... Rb/ Rb

(b)

~

t

T

- - 5e/ Rb- + - Zn/ Rb- - Sc/ Rb- - V/ Rb-"-Mn/ Rb

P--I~

11

11

Weeks ot Age

Weeks otAge

Fig. 1. Comparison of the uptake behavior of Sc, V , Mn,
Zn, and Se in the liver (a) and in the kidney (b) of LEC
rats at different age before jaundice development.

References
1) S. Ambe et al.: Chern. Lett. , 1991, 149.
2) S. Ambe et al.: Anal. Sci. , 1, Suppl. , 317 (1991).
3) S. Ambe et al: J. Radioanal. Nucl. Chern., 195, 297(1995).
4) H. Sakurai et al. : Biochem. Biophys. Res. Commun.,
184, 1393 (1992).
5) H. Sakurai et al.: ibid., 185, 548 (1992).
155

RIKEN Accel. Prog. Rep. 29 (1996)

Biodistribution of Multitracers in Normal, AI-Overloaded
and Cd-Overloaded MiceR. Amano, S. Oishi,* M. Ihyou,* A. Kakunaga,* Y. Yoshida,* T. Ishizaki~* T. Suzuki,*
S. Enomoto, and F. Ambe
Radioactive multitracer technique was applied to thesimultaneous evaluation of biobehavior of many traceelements in normal, AI-overloaded and Cd-overloaded
mice. Their tissue and subcellular distributions were
examined in brain, cardiac muscle, lung, liver, spleen,pancreas, kidney and skeletal muscle by using a radioactive multitracer solution,1-3) which was preparedfrom an Ag target irradiated with 135 MeV/nucleon
14N beam accelerated in RIKEN Ring Cyclotron.
Male ddY mice weighing 20-30 g were used. Physiological saline solutions, A1 3+ (1 mg AI/ml) andCd 2 + (0.5 mg Cd/ml) solutions were injected intraperitoneally (5 ml/kg) into three groups of mice,
namely, the control group, AI-overloaded group andCd-overloaded group, respectively. At 1 hr for AIoverloaded group, and at 3 hr for Cd-overloaded group
after injection of the A13+ or Cd 2 + solution, 0.2 mlof the radioactive multitracer solution was intraperitoneally injected. At 48 hr after injection of the multitracers, the mice were sacrificed under ether anesthesia
and the 8 tissues were excised, weighed and freezedried. The subcellular distribution for several tissues
was determined according to the modified method of
Hogeboom and Schneider. Radioactivities were measured using Ge "(-ray spectrometry.
Figure 1 compares the uptake rates ofSc , V, Mn, Co ,Zn, Se, Rb, Y, Zr and Rh in liver at 48 hr after injection
among the control, AI-overloaded and Cd-overloaded
mice. The values of Sc, Y and Zr of AI-overloaded
mice were substantially larger than those of control
and Cd-overloaded mice. The values of Se and Zn of
Cd-overloaded mice were slightly larger than those ofcontrol and AI-over loaded mice. Figure 2 shows thechanges of subcellular distributions of a Y tracer (A)and a Zn tracer (B) in liver between control mice and10 ,------------------------------ - - ~ ScOv
!SJ Mn!!!lI Co

o Zn
o Se

E:a Rb
~y

.Zr
O Rh

control

AI-overloaded

Cd-overloaded

Fig. 1. Uptake rates of Sc, V, Mn, Co, Zn , Se, Rb, Y ,Zr and Rh in liver at 48 hr after injection in control,
AI-overloaded and Cd-overloaded mice.
School of Health Sciences, Faculty of Medicine, Kanazawa
University

156

1 0 , . . - - - - - - - - - -- - - - - -- - - - - - - - ,••mitochondrial ~ supernatantnuclear• microsomal

Control

AI-overloaded Control

Cd-overloaded

Fig. 2. Comparison of tissue and subcellular distributions in liver between control and metal-overloaded
mice. (A): The change of subcellular percentages of Y
tracer by AI-treatment; (B): The change of subcellular
percentages of Zn tracer by Cd-treatment.

metal (AI or Cd)-overloaded mice. The uptake rateof the Y tracer in the mitochondrial fraction increased
significantly by the AI-overloading treatment. The uptake rate of Zn tracer in the supernatant fraction increased slightly by the Cd-overloading treatment.
AI-induced synergistic interactions were significantly
observed in the uptake rates of Sc, Y , and Zr tracers
in liver. These tracers are known to be localized in the
mitochondrial (containing lysosome) fraction. 4) In addition , the liver uptake of these tracers was increased in
the mitochondrial fraction by the Al injection. A large
amount of Al was also accumulated in the mitochondrial fraction of liver. Therefore, mitochondria and/or
lysosomes play an important role in the accumulationof Sc, Y , and Zr tracers and the AI-induced co-uptake
effects in liver. On the other hand, Cd-induced interactions were slightly observed in the liver uptake of Zn
and Se tracers. These tracers are known to exist in
the supernatant fraction mentioned above. Their liver
uptakes in the supernatant fraction were considerablyincreased by the Cd treatment. The Cd- induced synergistic effect of Zn tracer can be explained as follows:
metallothionein is freshly induced into the supernatantfluid and the content of metallothionein is increased
there by the Cd- treatment, and then Zn tracer incorporated into cell encounters the metallothionein withhigh probability and is bound to the metallothionein.
References
1) S. Ambe et al.: Chem. Lett., 1991, 149.
2) S. Ambe et al.: Anal. Sci. , 7 , Suppl., p. 317 (1991).
3) S. Ambe et al.: J. Radioanal. Nucl. Chem., 195 , 297(1995).
4) A. Ando and 1. Ando: Appl. Radiat. Isot. , 41 , 327(1990).

RIKEN Accel. Prog. Rep. 29 (1996)

Creating a New Design System Using a Cooled CCD Camera
Multi Spectrum Imager
Y. Okamoto, Y. Miyagi-Okamoto,* S. Enomoto, and F. Ambe
The accelerator can produce many types of radioisotopes. In their application to biology, a method to analyze their density and distributions is essential. In themultitracer technique developed at RIKEN , a numberof radioactive isotopes are simultaneously used to trace
different elements. 1 ) We design a new type of gamma
camera called Multi Spectrum Imager (MSI). It has a
new function to capture many types of radiation andalso visual light. Combination and comparison data of
the MSI and metabolic behavior of various elements
revealed using the multitracer technique will enable us
to determine the localization of various elements andthe time dependent metabolism on various tissues ofanimals and plants. 2 ,3)Figure 1 shows a diagram of the MSI. The object islocated in front of a fluorescence screen and the CCD
camera is at the back of the screen. The space from thescreen to the camera is surrounded by lead blocks andits interior darkened. The camera is connected to acomputer. The image data is downloaded to the computer and is analyzed by NIH Image 1.54 software. The
camera catches the light from the fluorescence screen
stimulated by the radiation energy. The camera also
catches the visual light . The CCD camera that we use
is a cooled type different from the conventional ones. It
has an excellent SIN ratio and low dark current. 4) Using this character, the camera detects very weak lightfrom the screen. Inserting different types of screens
between the object and the camera, the system can beapplied as a sensor yielding different spectra.

(b) BAS2000. For the , ray, the MSI had the same
sensitivity as the BAS2000, and the linearity was excellent. The visual-light image was only taken by the
MSI. X-ray image was superimposed onto the ,-ray
image easily (Fig. 3). All types of light and radiation
passed through the MSI in the same light path.
MSI

r=0996130....J~ 2000c<lI

0Fluorescence
ScreenLens

Cooled CCO
CameraFig. 1. System diagram of MSI.

The stepsamples were made from 4 mm¢ paper disks
and an Na99mTc04 solution. Zero, 1, 2, 3, and 4 ILl of
the solution were dropped onto each of the disks. Images of these disks were taken using both the MSI and
BAS2000 (made by Fuji Photo Film Co. , Ltd.). The
99mTc_MDP solution was also injected into a rat andthe distribution image of this isotope was taken. 5 ,6)Figure 2 shows 99mTc-grayscales for (a) MSI and
Kanagawa Dental College, Department of Oral and Maxillofacial Radiology

r=0 .977

3000....,=".v; 110
90

1000

70
50
0

1

4
2
3
sample (kBq/mm)

5

1

2

3

4

5

sample (kBq/mm)

(b)

(a)

Fig. 2. (a) 99mTc-Grayscale (MSI), (b) 99mTc-Grayscale(BAS2000).

(a)
Dark
Box

BAS2000
4000

150

(b)

Fig. 3. (a) Visual-light image (MSI) , (b) Superimposed
image (J ray and visual light).
.

We are planning the following four more experiments. First, we must find a suitable fluorescencescreen for, rays. Second, we will try to develop ascreen the (3 ray. Third, we will combine a high pure
germanium ,-ray spectrometer with MSI. And finally,
we believe that this system can be applied to autoradiography and chromatography.
References
1) F. Ambe: RIKEN Rev., No.4, p. 31 (1994).
2) S. Ambe et al.: 1. Radioanal. Nucl. Chern. , 195, 305(1995).
3) Y. Okamoto: Oral. Surg. Oral. Med. Oral. Pathol. Oral.
Radiol. Endod., 80, 115 (1995).
4) Technical Manual of Astromed CCD Camera.
5) BAS2000 Technical Manual, p. 48.
6) Imager 2 Functional Index (1995).

157

RIKEN Accel. Prog. Rep. 29 (1996)

TDPAC of 99Ru Arising from 99Rh in a-Fe203 and EuFe03
Y. Ohkubo, Y. Kobayashi , Y. Yanagida, T. Okada, K. Asai, and F. Ambe
Previously, we incorporated 99Rh ions into Fe304
and measured the hyperfine magnetic fields H hf at
99Ru arising from 99Rh by means of TDPAC and emission Mossbauer spectroscopy. 1) The temperature dependence of H hf and the isomer shift imply that the
Ru ion exists as a mixed state of Ru 2+ and Ru3+ andthat the unpaired 4d electron of the Ru3+ ion itself contributes to Hhf in addition to the A-O-B supertransfer
interaction. Several years ago, we also measured thehyperfine fields at 99Ru in o:-Fe203 using the same
techniques. 2) The isomer shift indicates that the Ru
ion exists as Ru3+. Figure 1 shows the temperaturedependence of Hhf at 99Ru in o:-Fe203 tentatively deduced from the frequency distributions of the TDPAC
spectra. A comparison of it with that for ll1Cd in
o:-Fe2033) suggests that besides the supertransfer interaction, the magnetic moment of the Ru 3+ ion also
contributes to H hf . However, the implied temperature dependence of the latter contribution is different
from that for Fe304' The Hhf produced by the Ru 3+
ion in Fe3 04 is a monotonically decreasing functionof the temperature, whereas that in o:-Fe203 seems
to be most significant at about 200 K. This time, wemeasured the hyperfine field at 99Ru in EuFe03 using
TDPAC and report the results. EuFe03 takes the perovskite structure and is an antiferromagnet with TN =dried o:-Fe203(99Rh) were milled and heated at 1300
° C for 5 h in air. The mixture was pressed into apellet and heated at 1300 ° C for 24 h in air to obtain
EuFe03(99Rh).4)
Figure 2 shows the measured TDPAC spectra of
99Ru in EuFe03 and their corresponding frequency distributions. We see at 80 and 293 K two peaks, labeled
1 and 2 , due to hyperfine magnetic interactions: Peak
1 corresponds to the Larmor frequency WL and peak
2 to 2WL. Thus, there is a hyperfine magnetic field at
99Ru. However, there is also a large broad peak, located below WL, hiding peak 1 at 376 K. We have notyet identified the origin of this peak. The peak seen at
717 K (> TN) is due to a quadrupole interaction andis considered to be different from the unidentified one.
Careful analysis of the TDPAC spectra for EuFe03 as
well as for o:-Fe203 is in progress using a fitting program code written on visual basic.
(a)

-0.15

(b)

10
°
+0.05
+0.10
-0.10 .
-0.05

:s

0

+0.05
J -0.1
5662 K.4)

f

80

60l

0
+0.05

~

40
+-

0

Btu at 99Ru.to

Hw- at lllCd -..>

50

()
0-

:;?
0

0.

.to.

20

~

+0.05
+0.1°0

o
o

J

200

SO

100
Time (ns)

TM
I

400

600

800

0

1000

Temperature (K)Fig. 1. Temperature dependence of the hyperfine magnetic field Hhf at 99Ru (_99Rh) in a-Fe203 . Temperature dependence of Hhf at lllCd (_lllIn) in a-Fe203(Ref. 3) is also shown for comparison. TM is the Morintemperature.

ISO

200

I
2
3
Frequency (ldlrad/s)

4

Fig. 2. (a) TDPAC spectra A 22 G 22 (t) of 99Ru (_99Rh)
in EuFe03 measured at 80, 293 , 376 , and 717 K , and(b) their frequency distributions. The solid curves in(a) represent the time spectra reproduced from the frequency distributions in (b). Peaks 1 and 2 in part b
correspond to the' Larmor frequency WL and 2WL.

References
Isotopically enriched 99Ru metal powder was irradiated with 13-MeV protons available from the RIKEN
AVF cyclotron. The (p, n) reaction produces 99Rh
from 99Ru. The irradiated 99Ru powder was treatedaccording to the chemical procedure described in Ref.
1 and o:-Fe203(99Rh) was thereby obtained. Stoichiometric amounts of high-purity powder of EU203 and

158

1) Y. Ohkubo, Y. Kobayashi , K. Asai , T. Okada, and F.
Ambe: Phys. Rev., B47, 11954 (1993) .
2) Y. Ohkubo and F. Ambe: RIKEN Accel. Prog. Rep. ,23, 75 (1989).

3) K. Asai, F. Ambe, S. Ambe, T. Okada, and H. Sekizawa:Phys. Rev., B41 , 6124 (1990).
4) C. Boekema, F. van der Woude , and G. A. Sawatzky:
Int. J. Magnetism, 3 , 341 (1972).

RIKEN Accel. Prog. Rep. 29 (1996)

Extraction of an Intense Slow Positron Beam Using He++ Beams
from the AVF Cyclotron
Y. Itoh, K. Lee, A. Goto, N. Nakanishi, M. Kase, and Y. Ito
Until the last year we had been trying to extract
slow positron beams by bombarding BN, AI, and Ni
targets with p+ beams, and bombarding Si 3 N 4 , C, andSi0 2 targets with d+ beams from the AVF cyclotron.
The intensity of the extracted slow positron beam wasvery close to the values estimated from the known dataof excitation functions of the nuclear reactions and of
positron energies emitted from the produced nuclides,
and from reasonable assumptions on the moderation
efficiency, geometrical efficiency, and so on. The results
show that about (lrv1.5) x 104 slow positrons/sec canbe extracted per p,A of p+ or d+. Comparing this value
with the theoretical estimate, the intensity is expected
to be increased by a factor of up to 5 by the improvement of geometries and moderator efficiency, but anincrease by an order of magnitude is inaccessible.

With the hope for a still more intense slow positron
beam we have searched for further possible targets that
produce positron emitters by irradiation with He++.
As the candidate targets we selected Ni, AI, and Si,
and the slow positron beam intensity was estimatedtheoretically and experimentally. For the theoreticalestimation we used the ALICE program to obtain excitation functions , and the TRIM program to obtain
depth-energy relationships. Other parameters necessary for the theoretical estimate, such as the branching ratio for positron emission per disintegration of thepositron emitter, the maximum energy of positrons,
and the absorption coefficient of positrons, were derived from a handbook. The conversion efficiency ofthe W moderator is taken to be 1 x 10- 4 • Two different geometries have been considered (see Table 1).

Table 1. Various targets for slow positron beam.

Target(Thickness/lJm)

Ni
(200)
AI
(550)
Si
(600)

Nuclear Reaction°maxmb (MeV)58Ni( a, pn) 6OCu 586 (27.0)

Calculated
Slow e+ (l04/secllJA)

MeasuredRatio ofSlowe+
Transmission
Transmission Reflection to Reflection (l04/sec/lJA)

5.86

1.81

3.24

1.30

7.56

1.69

4.47

1.19

9.41

2.40

3.92

(0.493)6oNi(a, pn)62Cu 786 (29.0)
27 A1(a, n)3Op

619 (11.0)

27Al(a, an)26AI

177 (32.0)

28Si(a, n)3 1S

117 (18.0)

28Si(a, pn)30p

547 (28.0)

In the reflection geometry, slow positrons are extracted
at 30 degrees backward to the incident He+ + beam,
while in the transmission geometry slow positrons are
extracted in the same direction as the incident He++
beam. In the latter geometry, the purely geometricalefficiency is larger by a factor of about 5, but the absorption of fast positrons in the target material is alittle larger. The ratio of extraction efficiency is 25 as shown in the next-to-Iast column in the Table.
Experiments were performed in the transmission ge-

ometry, and the results were (1.2 rv 1.3) X 104 slow
positrons/sec/ p,A of He++. This agrees in the orderof magnitude with the theoretical estimate. For Si theexperimental results were far smaller than the theoretical estimate. This small intensity was caused by anaccidental break of the Si target (0.3 p,m x 2) during
the He++ beam irradiation. Since the Si target is expected to give the largest intensity of slow positrons,
it is necessary to repeat the measurements.

159

RIKEN Accel. Prog. Rep. 29 (1996)

Resistivity Dependence of Positron/Positronium Annihilationin Porous Silicon
Y. Itoh, H. Murakami, and A. Kinoshita*
The porous Si layer formed by anodization of single crystalline Si (c-Si) in HF solution contains agreat amount of micro- and nano-meter pores. The
positron/positronium annihilation method is a very
useful tool for investigating the fundamental propertiesof porous silicon since positronium is formed at a relatively high rate in porous silicon. 1) The interaction between positrons and electrons confined in surface layers
should be an interesting subject for the application of
positron annihilation, and for clarifying the propertyof electrons confined in the Si surface layers.
Two boron-doped silicon wafers (diameter = 76 mm,
thickness = 400 J.Lm) with the different resistivities of
1 (sample A ) or 0.01 (sample B) n'cm, were used as
starting materials. Aluminum was deposited on one
side of the wafer surfaces (100), and annealed at 833
K for 15 min by current heating. The aluminum ohmic
electrode was uniformly pressed onto a positive copper
plate electrode mounted on a sample holder, and wasset opposite to a platinum electrode in an anodization
bath. The silicon wafer was anodized in HF solutionof 55 wt.% under d.c. current density of 52 mA/cm 2 .
The temperature fluctuation throughout the anodization was controlled within 3 K.
It is confirmed experimentally that the number density of pores on the anodized surface, n p , is equal to
the two-thirds power of their bulk concentration nB
in the starting materials. 2 ) The porosity P is obtained
from weight loss ~ w of the samples by anodization,and from the wafer thickness t as P = ~w/(S·t·O'si) 'where s is the anodization area and O'si is the densityof bulk crystalline Si, 2.34 g·cm- 3 . If we assume thatcylindrically shaped pores are oriented perpendicularly
to the sample surface and penetrate the anodized layer,
the pore diameter d is given by 2(P /7fn~e)1 / 2, andthe internal surface area S per cm 3 is 7fdnif3. These
quantities are listed in Table 1, where it is seen that
Table 1. Characteristics of porous silicon A and B.
SampleA
B
Boron concentration[cm -3] in starting bulk Si
1 X 10 16 6 X 10 18
Resistivity [0 . cm] of bulk Si
1
0.01
Thickness [J.Lm] pf porous Si
119
114
Porosity
0.50
0.35
Pore diameter [nm]383.7Internal surface
area [cm 2 . cm- 3 ]5.5 X 105 3.7 X 106
Tokyo Denki University

160

the internal surface area of the sample B is one orderof magnitude larger than that of A.
The sample was cooled to temperatures ranging
from 300 to 12 K in a chamber evacuated to 8 x 10- 4
Pa. Three lifetime components of about 0.2, 0.5, and35-45 ns were found for sample A, but only two of
about 0.2 ns and 0.5 ns were found for sample B. The
longest lifetime in sample A is attributed to the o-Ps
annihilation. Figure 1 (a) shows the temperature dependence of the longest lifetime 73 in sample A, which
decreased from 45 to 34 ns with a rise in temperaturefrom 12 to 300 K. Figure l(b) shows the temperaturedependence of 71 and 72 in sample B. The middle lifetime 72 and the shortest lifetime 71 were nearly independent of temperature up to 200 and 300 K, (72 ~520 ps, 71 ~ 241 ps) , respectively.

U)

15

<::

§40
~

...l

~

3.5

50

¥IH\i! "

~~fFd

35

#22~

t'l2.5

I

o t2

2

~

:315

1

Q

0.5

PcP

iQ:p:!:QJlJ:J:Q:Ftr:ft

~

30
0

100
200
Temperature IK

(a)

300

100
200
Te mpera lure I K

300

(b)

Fig. 1. (a): Temperature dependence of the longest lifetime of the sample A , (b): Temperature dependenceof the shortest and middle lifetime components of thesample B.

Since the longest lifetime 73 could not be observed in
Sample B, we believe that positronium is not formed.
The specific internal surface area of the pores in sample
B is one order larger than that in A , and the pore diameter in sample B is large enough to contain positronium. It means that there is sufficient condition to form
positronium in sample B. Nevertheless, the result that
positronium formation did not occur in sample B suggests that the physical and chemical properties of thepore surface are quite different from those in sample
A. We are currently undertaking further investigations
to clarify this point.
References
1) Y. Itoh et al. : Appl. Phys. Lett. , 63, 2798 (1993) .
2) A. Kinoshita et al.: Trans. IEICE (in Japanese), C-II,
J73-C-II, No.2, p. 129 (1990) ; H. Aoyagi et al.: ibid.,
No . 4, p . 135 (1995).

RIKEN Accel. Prog. Rep. 29 (1996)

Positron Annihilation Studies on the Interaction between
Hydrogen and Defects in Nickel
Y. Itoh, Y. Wu, and Y. Ito
Positron annihilation was measured for Ni crystals
containing different kinds of defects. The nickel crystals were annealed at 1173 K for 1 h and then slowly
cooled to room temperature. The annealed sample wasthen cold-rolled to different degrees of deformation to
introduce vacancies and dislocations. It was found thatthe lifetime spectrum could be fitted to a single component for annealed and cold-rolled nickels. The positron
lifetime increased by the cold-rolling, and at a strain
exceeding about 9% it reached a saturation value of
179 ± 1 ps (Fig. 1 (a)) , which is close to the value
71 v = 180 ps for positron trapping in a single vacancy.
Hydrogen was then doped by the catholic hydrogencharging method. The lifetime spectra of hydrogencharged samples could be decomposed into two components with 71 = 179 ± 1 ps and 72 = 390 ± 20 ps
and I2 = 5 ± 1%. The longer lifetime component is attributed to the formation of vacancy clusters. In viewof the appearance of a well separable long-lived component of about 390 ps, the hydrogen-vacancy composite
can become the center of vacancy agglomeration. This
is in accordance with the results of Johnson et al. 1)
In subsequent experiments the cold-rolled Ni wastempered at 473 K for 10 h to eliminate most of the vacancies but leaving the dislocation density unaffected.
The absence of the effect of hydrogen-charging in tempered nickel clearly indicates that hydrogen does notreact with dislocation. The interaction between hydrogen and vacancy-type defects may be the dominant reason for the increase of mean lifetime and Sparameter (Fig. 1) in the hydrogen-charged cold-rolled
nickel.
It is concluded that hydrogen is trapped at vacancies
and becomes a center of vacancy agglomeration, andthat dislocation sites are not responsible for the forma-

200(a) \II .• ...

~

<Zl

0...

. ......... ..................... ......................

180

~

E
~

'-

c

('j
~

160
140

2
0.56

(b)

!

!

!

v 0 .54

!~

~

~

....

~

....

~

E
ro
ro

0...

cJJ 0.52
0.50
0

10

20

30

40

Strain (0/0)
Fig. 1. The effect of hydrogen-charging on (a) the mean
positron lifetime and (b) S-parameter for cold-rolled
nickel samples. The strain introduced by cold-rollingis shown on the abscissa. Both vacancies and dislocations are thought to be present in the samples. 0
Cold-rolled Ni , • : hydrogen-charged cold-rolled Ni.

tion of larger vacancies. This observation is confirmedby measurements of the Doppler broadened annihilation radiation.
References
1) J. A . Johnson , P. S. Doubloon, and R. E. Smallmann:
Proc. Roy. Soc., A315, 231 (1970) .

161

4. Radiation Chemistry and Radiation Biology

RIKEN Accel. Prog. Rep. 29 (1996)

Track-Depth Resolved Dynamics of Excited States in Ion IrradiatedRare Gases near Condensed Phases
K. Kimura, W. Sekiguchi, Y. Yoshioka, T. Morita, M. Iimura, and W. Ron
The radiation effects induced by ion irradiation havebeen mainly on the primary collisions in physics while
product analysis have been major methods in chemistry and biology. As for the relevance between the two
approaches, we can find very few studies. This study
aims to elucidate the physico-chemical stages of ion irradiation by focusing on the dynamics of excited statesalong the ion track. This may be achieved by measuring the Bragg curve of the luminescence from the trackin the condensed phase; for this, we developed a digital camera for the ion track, a track scope, composedof an imaging fiber mounted in a cryostat and a position sensitive photon counter. This allows us to obtain
depth dependent luminescence spectra, efficiency, anddecay. The depth can be converted into several parameters including derivatives of ion energy, stopping
power, velocity, and relative excitation density. In ourprevious study of helium, we found that the luminescent states , upper level excimers, originate from the recombination between the lowest triplet excimers. The
regeneration of upper level excimers increases along the
Bragg curve, and near the Bragg peak, the reactionsof the three excimers occur to result in the quenching. An extra Bragg peak caused by the Fano-typemechanisms was observed near the termination of the
track.
Now the study are extended to other rare gases.
With increasing atomic number, rare gases evolve inelectronic properties such as excited states , the electronic conduction level in the condensed phase (V o),and the electron mobility. These effects on the physicochemical stage will be studied. We developed a modified track scope essencially composed of the same parts
to the previous one but can pressurize gases up to 40
atm near the critical temperature, resulting in nearly
condensed gases. The track length could therefore be
adjusted by altering the pressure. This track scopeis illustrated in Fig. 1. A capillary plate was used totransmit only the luminescence perpendicular to thetrack. Figure 2 shows the specific luminescence dL/dx
vs. the track depth in Ar-ion irradiated dense argongas . The luminescence is vacuum ultra violet light originating from argon excimers. The dL/dx is damped
earlier than the stopping power, which is quite different from the result in case of the helium sample. The
high-density excitation can enhance the luminescencein helium while it is quenching in this case.
Figure 3 shows the luminescence efficiency (dL / dE)
as a function of the velocity of ions; dL / dE rises toward
the termination of the track. Similar results were observed for other rare gas samples. The results counter

A: a beam slit by 0.1 X 2 mm
B: a capillary plate
C: a quartz imaging-fiber of a 2 X 2 mmcross section
D: a cold part of the trackscope
E: connection to a pump 'and gas bombes
F: a lens system
G: an intensified CCD camera
H: connection to a computer system.

Fig. 1. A track scope.

1000
d
L

~ 500
X

Fig. 2. The specific luminescence intensity dL/dx vs. thetrack depth of Ar-ion irradiated Ar gas.

1000

500

Fig. 3. The luminescence efficiency as a function of the ion
velocity obtained by the convert ion of data from Fig. 2.

to what scintillator theory and experiments have indicated. This may be explained by the charge exchange
and direct excitation processes which were also important in the appearance of the 2nd Bragg peak in thehelium sample.
References
1) K. Kimura: Phys. Rev., A47, 327 (1993).

163

RIKEN Accel. Prog. Rep. 29 (1996)

Unusual Temperature-Dependent Decay of Self-Trapped Excitons
Formed at High Density in Ion Irradiated BaF 2
K. Kimura, Y. Yoshioka, W. Sekiguchi, T. Morita, M. Iimura, K. Ushida, and W. Hon
Recently, the luminescence of photo excited BaF 2
and several alkali halide crystals have attracted interest not only as new scintillators for high energy physics
but also as crystals that demonstrates the new exciton luminescence called Auger electron free luminescence (AEFL). We have studied the dynamics of exciton luminescence, induced by irradiation with several
kinds of ions oflow energies of about 2.0 MeV/nucleon,
by developing techniques for fast luminescence decay
measurements (SISP) of 100 ps resolution. Excitationdensity dependent shortening of the lifetime of AEFL
was found newly, which were reported already.1) The
present report describes the effect of ion irradiation
with temperature changes on the self-trapped exciton(STE). It was found previously2) that at room temperature, the He-ion irradiation caused drastic lifetime
shortening of the STE compared with the photo- andelectron-irradiation, which is shown in Fig. l. Heavier
ions caused increased shortening of the STE lifetime.
Under our condition of the high density excitation,
which is intensified with increasing mass of the projectile ion, the STE decays according to the STE-STE exchange interaction in addition to the spontaneous process. The competition rate equations could be solved
analytically. The instantaneous luminescence intensity, I( t), can be expressed by the following equation:
I(t) = k/[(a + N(O)-l) exp(kt) - a]

(1)

1000

5000

TIMElns

10000

15000

Fig. 2. Fitting of Eqn. (1) to the decay curve for He-ion
BaF 2 .

radiation which results in a lengthening of the decay
time from about 1 JiB at room temperature to about 10
J-LS at 50 K.4) Both effects of temperatures and masses
projectile ions are shown in Fig. 3 comprehensively.
The results may be explained by the high-density excitation which is mentioned briefly in the following sentences. The slow rises in cases of photo- and electronirradiation in Fig. 1 suggest that STE's can be regenerated through the recombination of holes (H-centers)
and electrons (F-centers). The decrease in temperature should slow down the rate of these recombinations. By contrast, in case of the ion irradiation, theF- and H-centers are formed at such a high density thatneither can localize separately and they are always able
to recombine. Decreasing temperatures suppress the
expansion of the volume covered by F - and H-centers
so that the density of STE increases.

where N(O), k, and a stand for, respectively, the number density of STE at time 0, the rate constant of
spontaneous luminescence of STE, and a constant dependent on the radii of the track and STE and on thecritical exchange interaction. This equation could simulate the result fairly well (Fig. 2).

H.

- r o o m temp .
• ------ temp. change""to3SK
10

Hall Lile /ns~ouFig. 3. Temperature and the mass of projectile dependencies of the lumin~scence efficiency and the half-life.

'00

References
TIMElnsFig. 1. A comparison of the decay of STE in BaF 2 induced
by different sources.

Decreasing temperatures shortened the decay timefrom several ns to about 400 ps with no prominentchange in its intensity.3) This temperature effect wascontrary to that for photoirradiation by synchrotron

164•1) K. Kimura et al.: Phys. Rev., B48, 15535 (1993).
2) K. Kimura: Nucl. Instrum. Methods Phys. Res., B90,
100 (1993); K. Kimura and H. Kumagai: Rad. Eff. Def.
Solids, 126, 45 (1993).
3) K. Kimura: to be published on Nucl. Instrum. Methods
Phys. Res. , B (1996) and J. Elec. Spec. Re. Phenomena(1996).
4) C. Shi et al.: Physica Scripta, 41 , 1022 (1990).
5) Shibata et al.: Private communication.

RIKEN Accel. Prog. Rep. 29 (1996)

Effect of Heavy-Ion Beams during the Fertilization
Cycle of Plants
T. Abe, S. Kumata, T. Torashima, S. Kitayama, and S. Yoshida
During the fertilization cycle of some plant species,
there is an optical period when certain chemicals can
induce mutagenesis at a high frequency. I) An acceler. ated ion beam can also elicit mutagenesis when administered during the fertilization cycle and its effect canbe made within extremely short time periods becauseof it 's relatively high LET compared to other energy
beams such as ,- and X-rays; the irradiation area canbe limited to a specific stage and organ avoiding undesired damage to other plant tissues.
In this study we examined the effectiveness of ion
beams in inducing mutagenesis in the embryo of thetobacco plant (Nicotiana tabacum L. cv. BY-4). Sev-

eral ovaries at different developmental stages, 24- 36,
48- 60, 72- 84 and 96- 108 hrs after pollination, were
irradiated with a N-ion beam (135 MeV lu). The MI
seeds were harvested one month after irradiation, andthen germinated in an 1/2 MS agar medium. After a
two week incubation, we determined their germinating
rates and observed the shapes of the MI seedlings.
A high irradiation dose at almost any developmental stage caused a decrease in germination percentage
and an increase in the number of chlorophyll deficientplants (CDP). The stage at which ion beam treatment
is most effective in causing the production of CDP is
72-84 hrs after pollination (Table 1). We are con-Table 1. Frequency of chlorophyll deficient plants (CDP) induced with
the ion-beam treatment at various flowering stages.
Stage oftreatment
Control
24- 36 hrs
48- 60 hrs
72- 84 hrs
96- 108 hrs

No. oftreated flowers
4
6
6
5
4

Germination

(%)
97.8
74.9
78.3
74.8
85.4

tinuing to monitor and analyze MI plants and theirprogeny. If ion beam treatments consistently resultin a high mutation rate and a wide range of mutant
phenotypes, this work will significantly contribute to

Seeds weight
mg/100seeds
7.7
4.6
3.7
4.7
6.2

No. of Ml
seedlings
2968
6051
6428
2728
2719

No. of
CDP
0
8
19
17
13

Frequency(xlO - 1 %)
0.0
1.3
3.0
6.2
4.8

future studies of many subjects in molecular biology.
References
1) K. Kang and T. Kameya.: Euphytica, 69 , 95 (1993).

165

RIKEN Accel. Prog. Rep. 29 (1996)

Enhanced Cell Inactivation at Nonpermissive Temperature
S. Kitayama, A. Tanaka, N. Shikazono, and N. Inabe
When DNA is damaged in living cells, many physiological changes such as the suspension of normal DNA
replication, induced synsthesis of protein etc. will beobserved. However, almost all of the cells have repair
capability for such lesions and can survive within thesublethal dose. However, many intracellular or environmental factors will influence their recovery process
and consequesntly change the surviving fraction. The
repair efficiency of DNA lesions depends on the typeof damage, the cells genetically-controlled capability
for repair, and, again, its physiological environment.
Therefore, a comparison of repair efficiency under thesame physiologcal condition will contribute to elucidate the difference in damages or repair process involved in the cell recovery.
Deinococcus radiodurans, the most radiation resistant bacterium, can survive even after the inductionof many lesions in and various kinds of damage toDNA. The principal reason for this tolerance is an efficient and accurate repair mechanism for such DNA
lesions. 1 ) We have reported that the interruption of therecovery process reduced greatly the surviving fraction. Post-incubation at a nonpermissive temperature (42°C) also reduces the cell survival following
the physical or chemical treatments that cause DNA
damage. Even the fragmented DNA by gamma irradiation are rejoined in the cells, their colony forming
ability (survivor) was reduced by post incubation at 42°C for 6 hours. In the previous experiments Q-particles
were used for the bombardment with accelerated particle and the changes of DNA molecular weight wereanalysed by sedimentation. 2) Since the bombardmentwith a-particles in a liquid phase is thought to include
a substantial low LET fraction , Ne-ions (135 MeV / J.l)
were used in this experiments. Pulse field gel electrophoresis (PFGE) was also used for these analyses (Fig.
1) because it has been recently become useful for the
analysis of high molecular weight DNA.
As shown in Fig. 2 the enhanced lethal effects ofincubation at 42°C for 6 hrs following the sublethal
doses of Ne-ion irradiation is lower than that with Qparticles reported previously.2) Therefore , comparative
experiments using ')'-ray irradiation or treatments withsome radiomimetic chemicals will be carried out to obtain some conclusive evidence.

5.0

2Time of Postincubation(hr lFig. 2. Cell survivors after incubation at nonpermissive
temperature following Ne-ion bombardment. Colony
forming units of unirradiated cells (circle) , irradiatedwith 1 kGy (square) or 1.5 kGy (triangle). Following
the irradiation cells were postincubated a t 30 ° C (opensymbols) or 42 ° C (closed symbols) for 6 hrs and wereplated on TGY-agar.
Fig. 1. Pulse field gel electrophoresis of DNA in the cells
post-incubated at 30 °C or a nonpermissive temperature. Unirradiated control (lane 1), 1 kGy (lane 2) , 1.5
kGy (lane 3) , 1 kGy and postincubated at 30°C (lane4), 1.5 kGy and post-incubated (lane 5) , unirradiatedbut incubated at 42 ° C (lane 6) , 1 kGy and postincubated at 42°C (lane 7), 1.5 kGy and post incubated at
42 °C (lane 8), A-ladder DNA marker (lane 9).

166

References
1) S. Kitayama and A. Matsuyama: Biochem. Biophys.
Res. Commun., 33, 418 (1968).
2) S. Kitayama et al. : Agric. Biol. Chem ., 41, 2297 (1977).

RIKEN Accel. Prog. Rep. 29 (1996)

Effects of Ne Ion Beams on the Survival of Arabidopsis thaliana
N. Shikazono, A. Tanaka, Y. Yokota,* H. Watanabe,** S. Tano,**T. Kanai, and S. Kitayama
The biological effects of heavy charged particles,
measured by the relative biological effectiveness (RBE)on lethality as a function of linear energy transfer(LET), have been extensively studied in bacteria, yeast
and mammalian cell cultures. However, the effects ofheavy ions on multicellular organisms are still not fully
understood. Arabidopsis thaliana (L.) Heynh. is a particularly suitable multicellular organism for studying
the effects of heavy ions and other kinds of radiation
because its seeds and plants are small, it produces alarge number of seeds and plants , and its life cycle isshort. 1 )We have investigated the effects of heavy ions on thesurvival of Arabidopsis using heavy ions with a LET
of 17- 549 keY I /-Lm , and found that the highest RBE
value was obtained by Ar ion irradiation (LET 252
keY I /-Lm).2) In addition, we determined the characteristic survival curve for N e ions (LET 549 ke V I /-Lm) .
The typical survival curve for other ions showed ashoulder at lower doses and a steep decline from thelevel obtained by a critical dose that depends on thekind of ion and its energy. In contrast, the survival
curve for Ne ions with a LET of 549 keY I /-Lm consistsof a gentle slope with no shoulder. This result cannot
be simply interpreted as an "overkill effect" , since thesurvival curves for heavier ions with LETs higher than
549 keY I /-Lm still have shoulders. 1 ) To further elucidate
the dependence of RBE on LET, we used Ne ions ofvarious LETs.
The dry seeds of A rabidopsis thaliana ecotype
Columbia were used for these experiments. An monolayer of seeds sandwiched between kapton films (7.5/-Lm thickness) was exposed to N e ions at the RIKEN
Ring Cyclotron. The LETs for Ne ions were varied byplacing an absorber in front of the irradiation site. The
mean LETs were calculated by ELOSS code (modified
OSCAR code). Seeds were irradiated by Ne ions of
three different LETs (156, 275, 525 keY I/-Lm ), and theplants were grown at 23 0 C under continuous light (40/-LE/m2 Is); the survival was measured one month aftersowing. We scored plants with expanded rosette leaves
as survivors.
The survival curves for Ne ions with LET 156, 275
and 525 keY I /-Lm are shown in Fig. 1. Ne ions with
LET, 156 keY I f..Lm , had the largest shoulder, while

50

100

150

200

250

300

Dose (Gy)Fig. 1. Effects of Ne ion beams with different LETs on survival. 0: LET 156 keV/j.Lm, .: LET 275 keV/j.Lm, 6:
LET 525 ke V / j.Lm.

those with LET, 275 ke V I f..Lm, had the smallest. The
size of the shoulder with LET 525 ke V I f..Lm was intermediate. These survival curves were typical and were
not similar to the curve for Ne ions with LET 549
ke V I f..Lm. Consequently, the condition of energy deposition accounting for the characteristic curve for Ne
ions with LET, 549 ke V I f..Lm, still remains unclear.
D37 for Ne ions with LET, 525 keY I /-Lm , was not
significantly different from that for LET, 275 ke V I f..Lm.
This explains the relatively high RBE of survival when
the N e ions had LETs to 500 ke V I f..Lm. In unicellular
systems, ion beams with LETs more than 200 ke V I f..Lm
usually reduce the RBE value. The difference in how
the LET values affect the RBE peak in unicellular systems and A rabidopsis might be explained by the existence of specific repair mechanisms which operate inmulticellular organisms.
Further investigations using other pa~ticles with
LETs of around 500 ke V I f..Lm would be important tomake clear the relationship between RBE and LET in
A rabidopsis and to understand the under lying mechanism(s) of the characteristic survival curve.
References
1) U. Bork et al.: Adv. Space Res. , 9(10) , 117 (1989).
2) A. Tanaka et al.: 5th Workshop on Heavy Charged Particles in Biology and Medicine, GSI, Darmstadt, Aug.
23- 25, p. 87 (1995).

Beam Operation Co.
Advanced Science Research Center, JAERI167

RIKEN Accel. Prog. Rep. 29 (1996)

Dependence of Interphase-Death Induction on the LET of
Accelerated Neon-Ions in CHO Cells
H. Sasaki, F. Yatagai, T. Kanai, and F. Hanaoka
Cultured mammalian cells exposed to moderate
doses of X-rays « 10 Gy) usually die after dividing at least once (reproductive death). However, wepreviously found that HeLa cells frequently die before
dividing (interphase death) after exposure to as low
as 1- 2 Gy of alpha particles from 241Am.1) This suggests a predisposition to interphase death when cells
are exposed to high LET radiations. The purpose ofthis study, which makes use of heavy-ions accelerated
by the RIKEN Ring Cyclotron, is to verify this hypothesis. First, we observed HeLa cells exposed to 3
Gy of Ne-ions (135 MeV lu; 102 keY IJ.Lm) using timelapse photography and found that about 30% of thecells died after detaching from the plate as if they
were entering mitosis. Since it was clear that thisdeath process was apoptotic and involved DNA fragmentation, as also observed in other cell lines (CHO,
FM3A) , we employed an apoptois-induction assay (indirect method) to elucidate the effect of the LET of
Ne-ions on the induction of the interphase death of
CHO cells.
CHO cells, which were destined to undergo interphase death after irradiation, remained in the G2 phase
for an extended period (> 24 h) and then became giant
before dying by apoptosis. Caffeine induces apoptosis
in these cells within a short period; the caffeine probably disturbs a check-point control mechanism in theG2 phase. In this study, cells were incubated for 24 hafter exposure to graded doses of Ne-ions with different
LETs (63- 341 keY I J.Lm) and then treated with caffeine(10 mM) for 1 h. The fraction of cells undergoing interphase death was estimated.by counting round cells (detaching apoptosis-initiated cells) which appeared after
the addition of caffeine. The results in Fig. 1 indicatethat the induction of interphase death-related apoptosis depends on the LET of Ne-ions. The maximum
effect (RBE = 4.6) was observed at 228 keY I J.Lm for
Ne-ions compared to X-rays at the half maximum level(35% induction). Evaluation of LET dependence forinduction of interphase death by means of time-lapse
observation (direct method) is now in progress and preliminary results are shown in Fig. 2. A similar RBE(4.2) was obtained for 228 keV/J.Lm Ne-ions.

168

80~-----------------------------,

60

en

'iii
o

Q.

o

Q.

<

40

---0--

20

X-ray----..-

Ne-ion(63keV/um}---0-

Ne-ion( 102ke V/um}---tr-

Ne-ion(228keV/um}
Ne-ion(341 keV/um}

O~--~--.---~-.,-~---.--~--~

a

20

40

60

80

Dose(Gy)

Fig. 1. Dose-response for apoptosis induction in CRO cells
exposed to X-ray or accelerated neon-ions with different
LET.

100~-----------------------------,

=

80

as

Q)

C
Q)

cn
as

60

.s::.

e-

o!

.:

40

---.-

X-ray

---<r-

Ne-ion(228keV/um)

30

40

50

60

Dose(Gy)

Fig. 2. Dose-response for interphase-death induction in
CRO cells (Time-lapse observation).

References
1) R. Sasaki: Radiat. Res., 99, 311 (1984).

RIKEN Accel. Prog. Rep . 29 (1996)

The Role of DNA Repair on Cell Killing by Neutronand Heavy-Ion Beams t
K. Eguchi-Kasai, M. Murakami, H. Itsukaichi, K. Fukutsu,* T. Kanai,
Y. Furusawa, K. Sato,** H. Ohara, and F. Yatagai
It has been suggested that initial double-strand
breaks (dsb) in DNA correlate well with cell death induced by conventional radiations. I) However, this is
not true for radiations with high linear energy transfer (LET). In these cases, the relative biological effectiveness (RBE) for cell killing is high, ranging from
2 to more than 10, but the RBE for dsb induction
is approximately 1 for particles with LETs below 300
keV I j.Lm 2 ,3) or even smaller than unity for very highLET ions. 4 ,5)Therefore, it can be deduced that it is not simple
dsb, but non-reparable breaks that are responsible forthe lethality of high LET radiation. 6- 8 ) Here, we haveexamined the effectiveness of high LET radiations on
causing cell death in 19 mammalian cell lines including
radiosensitive mutants.
The radiations used in this work were fast neutrons
from the NIRS cyclotron, and low (at NIRS, initialenergy = 12 MeV lu) or high (RIKEN Ring Cyclotron,
135 MeV lu) energy charged particles.
Some of the radiosensitive cell lines, such as LX830,
M10, V3, SX9, SX10 and L5178Y-S, are deficient inDNA dsb repair. In our experiments they showed
lower values of RBE for fast neutron-beams comparedto their parent cells. Their average RBE value was
1.23 ± 0.15 (mean ± standard deviation) while thatof their parent cell group was 1.86 ± 0.16. The othercell lines, human ataxia-telangiectasia fibroblasts, irs
1, irs 2, irs 3 and irs lSF, are also radiosensitive but
known as proficient in dsb repair; their RBE measured
a moderate 1.68 ± 0.15. The RBE values for the threegroups differ significantly (p < 0.05).
The RBE values varied depending on the radiation

quality and on the cell types. The RBE value wassmaller for low LET He-ion beams and larger for high
LET C- or Ne-ion beams, when both were compared toneutron-beams. Dsb repair deficient mutants demonstrated low RBE values close to unity for heavy ions;this was independent of the kind of ion beam or its
energy. The inactivation cross sections of 2 dsb repair
deficient cell lines (MID and SL3-147) increased withincreasing LET. They were always larger than those of
their parents (L5178Y and LTA) for all the LET ranges
tested up to 330 keY I j.Lm. With increasing LET, however, the difference in inactivation cross section between the mutants and their parents became smaller.
This suggests that the DNA repair system is less effective in response to high LET radiations, even in DNA
repair proficient cells. This is because the induction of
reparable dsb decreases and the ratio of non-reparable
dsb to total dsb increases with increasing LET.
Based on these findings, we suggest that the maincause of cell death induced by high LET radiations is
non-reparable dsb, which are produced at a higher rate
than when cells are exposed to low LET radiations.
References
1) L. R. Radford: Int. J. Radiat. Biol., 49, 611 (1986).
2) I. Furuno et al.: ibid. , 36, 639 (1979).
3) T. J . Jenner et al.: ibid., 61, 631 (1992).
4) J. Heilmann et al.: Radiat. Res., 135, 46 (1993).
5) K. J. Weber and M . Flentje: Int. J. Radiat. Biol., 64,
169 (1993).
6) D. Blocher: ibid., 54, 761 (1988).
7) K. Eguchi et al.: ibid., 5 2, 115 (1987).
8) M. A. Ritter et al.: Nature, 266, 653 (1977).

Condensed from the article in Adv. Space Res., 18, 109(1996).
Division of Radiobiology and Biodosimetry, National Institute of Radiological Sciences
Deputy Director in General, National Institute of Radiological Sciences

169

RIKEN Accel. Prog. Rep. 29 (1996)

Analysis of Mutations in the Human HPRT Gene Induced byAccelerated Heavy-Ion Irradiations (II)F. Yatagai, N. Inabe, K. Eguchi-Kasai, Y. Furusawa, M. Suzuki, M. Watanabe, T. Kato,* and F. Hanaoka
Knowledge of the specificity of mutations induced
by a variety of mutagens has enabled better understanding of the molecular mechanisms of mutagenesis.
The mutations induced by various types of chemicals,and UV and conventional ionizing-radiation, have been
analyzed extensively at the molecular level to gain insights into the induction mechanisms, but only a few
studies have been published on the characteristics ofheavy-ion-induced mutations. We have analyzed the
hypoxanthine phosphoribosyltransferase (HPRT) mutations in human embryo (HE) cells induced by Cions adjusted to different LETs (39, 68, 124, or 230
keV/j.Lm).l)
The deletion pattern of each exon region in the hprt
locus is dependent on the LET, as revealed by the analysis of multiplex PCR products of genomic DNA in
the mutants. Most of the mutations induced by 124
keY / j.Lm C-ions showed deletion of almost the entire
locus of the hprt gene. None of the mutations caused
by 230 keY / j.Lm C-ions involved such large deletions,despite the much greater energy deposition within theirtracks. To characterize the 230 ke V / j.Lm mutations, thesequence alterations in a cDNA of the hprt gene were
determined for 18 mutant clones. 2) The loss of exon
6 was the most frequent mutational event (10 clones),
and that of both exons 6 and 8 was the next most frequent event (6 clones). In two cases, the mutations
consisted of base substitutions. Further analysis of theintron regions on genomic DNA from mutants carrying
exon losses support the possibility that the mutations
were induced by aberrant mRNA splicing.
Is this characteristic specific to high-LET irradiationthat exceeds the peak of RBE (Relative Biological Effectiveness)? We used the human lymphoblastoid celllines, WI-L2-NS and TK6, to study this question. In
this series of experiments, we adjusted the energy ofions to three different LETs, one at nearly the initialenergy, one at the RBE-peak, and one at the level justbefore the stop of the ion. The survival curves for bothC- and Ne-ions are shown in Fig. 1 and a comparisonof the radiosensitivity with that for X-rays at DlO dose,the so-called "calculation of RBE" , is made in Table 1.
The expected LET effect on cell viability was observedwith the WI-L2-NS cell line. The mutation frequencies at certain survival rates were also determined andlisted in Table 2. Although the precise RBE cannot be
estimated because of the small number of trials, thetendency of RBE seems to be similar to that for cell
viability.
The data on TK6 cells is not yet complete enough
School of Medicine, Osaka University

170

(8)

C· lo n.

(b)

Ne·lons1.0~

u: 0 .1
:;
"
~
rn
0>

Dose(Gy)

Fig. 1. Survival curves of WI-L2-Ns for C- and Ne-ions.
Irradiation by 13 keV / J-Lm of C-ions was performed at
HIMAC.
Table 1. RBE Values for a lethal effect in WI-L2-NS cells.
Ion
LET (keV / J-Lm)
RBE at DlO

C
13
1.0

C
122
3.0

C
220
1.5

Ne
63
1.5

Ne
120
2.4

Ne
340
1.0

Table 2. Mutation frequencies of WI-L2-NS cells.
Ion
LET (keV /J-Lm)
Dose (Gy)Surviving fraction
Mutat. freq . (x 10- 6 )

0
1.0
3.7

C
13
2.0
0.25
13

Ne
120
1.0
0.173
27

Ne
340
3.0
0.172
14

to judge such LET effects on them. The study of thiscell line needs to continue, because a difference in boththe type and level of p53 protein between these two celllines has been reported to account for the differences intheir radiosensitivities. 3 ) It is also important to analyze
the isolated mutant' clones at the DNA sequence level.
References
1) M. Suzuki, M. Watanabe, M. Kanai, Y. Kase, F. Yatagai, T. Kato, and S. Matsubara: Adv. Space Res., 18,
127 (1995).
2) Y. Kagawa, F. Yatagai, M. Suzuki, Y. Kase, A.
Kobayashi, M. Hirano, T. Kato, M. Watanabe, and F.
Hanaoka: J. Radiat. Res., 36, 185 (1995).
3) W. Zhen, C. M. Denault, K. Loviscek, S. Walter, L.
Geng, and A. T. M . Vaughan: Mutat . Res., 346 , 85
(1995).

RIKEN Accel. Prog. Rep. 29 (1996)

Early Phase Histological Changes of Skin after Carbon Ion
Slit-Beam Irradiation
H. Tatsuzaki, H. Takahashi, T. Okumura, and F. Yatagai
Heavy ion treatment of cancerous tumors increases
the cure rate of other therapies. Although the cure rateincreases as the dose of irradiation increases , the size ofthe prescribed dose is limited by the tolerance of normal tissue. That tolerance depends on many factors,
including the LET and the volume of irradiation. We
have shown that the smaller the volume, the greater
the tolerance. I) We used the skin of the mouse to study
more closely the effects of irradiation on normal tissue.
The preliminary results were shown in this article.
We used twelve week old female C 3 H/He Sic miceraised under Specific Pathogen Free (SPF) conditions.
All the irradiation was performed at the RIKEN Ring
Cyclotron using the entrance plateau portion of an
original mono-peak beam from a 135 MeV / u C-ion
beam. The LET value of the beam at the skin surface
was around 22 ke V / f.1. 2) The beams were collimatedto a 25 or 5 mm width slit-shape to vary the volume
irradiated.
Seven days before irradiation, the lower hind legsof the mice were shaved. The legs were then irradiated with 60 Gy while they were under anesthesia(65 mg/kg sodium pentobarbital, i.p. injection). The
skin reaction typically progresses from erythema todry desquamation, then moist desquamation and thenhealing. The reaction is most severe from 14 days to 25
days after irradiation. 3 ,4) Histological specimens weretaken on the 13th, 17th, 21st, and 27th day after irradiation. At those time points, the mice were sacrificed
by an overdose of inhaled ether. Before amputation,
the extended irradiated legs were fixed to a wooden
plate with pins to prevent the skin from shrinking. The
legs were then amputated, fixed in 10% formalin solution together with the wooden plate, and embedded
in paraffin. The sections were prepared in the longitudinal direction, perpendicular to the beam entrance
surface. The specimens were stained by hematoxylin
and eosin (H&E) and observed under a light microscope. Un-irradiated skin was used as controls.
After 5 mm slit irradiation the thickness of the epidermis markedly increases. It reaches its maximum
thickness by the 17th to 19th day after irradiation andthen decreases slightly. The changes in the thicknessof the epidermis, measured at the middle of the irradiated area, are shown in Fig. 1. The measurement was
taken at the point of the papilla dermis to avoid interference by hair follicles. We observed no defects in theepidermis. The thickness of the dermis shows the sametendency and becomes maximally large at the 13th day.
The hair follicles measured 30 to 50 f.1m in diameter in

100 r -- - - - - 4....- - -

E 90
2:

80

(j')

E

.gj

'15..

70
60

Q)

50

~

40

I

(j')

~
.::£

(J

:£

30
20

10 I
0'----'-_--L.._...l----1_---L_

o

5
10
15
20
25
30
time after 5 mm slit irradiation (day)Fig. 1. The changes in the thickness of the epidermis after
5 mm slit carbon beam irradiation. The closed circles
and vertical lines indicate the range of thicknesses. Dayo shows the thickness of un-irradiated skin.

un-irradiated skin. By the 13th day after irradiation,
their diameter reached 100 f.1m. After the 17th day, thehair follicles gradually .disappeared. Desquamation of
the horny layer was evident on the 27th day.
A different profile emerged after 25 mm slit irradiation. By the 17th day, the epidermis had disappeared
from almost the entire irradiated area. Thickening of
the epidermis was seen only at the edge of the irradiated area and its length was around 1 mm. The dermis of the irradiated area thickened slightly to 200 f.1mfrom a control thickness of 25 to 100 f.1m, and the hairfollicles were destroyed. Necrotic tissue was attachedto the uncovered surface of the dermis and remainedthat way until the 27th day. The size of the thickened
part of the epidermis at the edge of the irradiated area
increased gradually to 3 mm by the 27th day.
This results suggest that smaller volume irradiation
cause less injury to normal tissues. Thus, reduction ofirradiated volume using the particle radiation therapy
to cancers is important.
References
1) T . Tatsuzaki et al.: in Extended Abstracts.
4th
Workshop on Heavy Charged Particles in Biology andMedicine, G. Kraft (ed.), Gesellshaft fiir Schwerionenforschung mbH, Darmstadt, Germany, p. G5 (1991).
2) T. Kanai et al.: Proc. 2nd Workshop on Physical andBiological Research with Heavy Ions, K. Ando and T.
Kanai (eds.) , Natl. Inst . of Radiol. Sci. , Chiba, p. 1
(1992).
3) H. Aizawa: Nippon Acta Radial., 33 , 602 (1973).
4) A. E. Pearson and G. G. Steel : Int. J. Radiat. Biol., 44 ,
353 (1983).

171

RIKEN Accel. Prog. Rep. 29 (1996)

Measurement of Potassium, Rubidium and Cesium Influx Rate into
Rat Erythrocytes Using Multitracer Technique
N. Ito, 1. Kunugiyama, A. Iwatsuki, S. Enomoto, S. Ambe, B. Liu, and F. Ambe
Since rubidium (Rb) and cesium (Cs) have physicochemical properties similar to potassium (K), many biologists have been interested in the kinetics of these alkalin~ metal elements. 1) Rubidium is present in mammalian tissues at a higher concentration than thatin the external environment. However, it has beenshown that Rb cannot completely substitute for K in
mammals despite the two element's similarities.2) We,
therefore, studied qualitatively the discrimination by
the potassium transport system (like Na+ -K+ ATPase)
between K and Rb, and between K and Cs using theMultitracer.
Erythrocyte samples withdrawn from Wistar rats
under general anesthesia were used in these experiments. A multitracer solution was obtained from agold foil target irradiated with a 14N beam accelerated by the RIKEN Ring Cyclotron, then the tracer
solutions, containing either 43K, 83Rb, 84Rb or 129CS,
were extracted from the multi tracer solution by an ion
exchange resin. The tracer solutions consisted of the
tracer in phosphate buffered saline (PBS): K (3 mM6 mM), Rb (0.3 f.1 M-6 mM) and Cs (7 nM-6 mM).
The range of potassium concentrations used was determined based on that found in rat plasma (from 3
mM to 6 mM). The lowest concentrations of Rb and Cs
used match their abundance in nature, and the highest
concentrations used were fixed at 6 mM , the highest
concentration of K in rat plasma. Gamma-ray spectroscopy was performed using a HPGe detector and amultichannel PHA.
The erythrocyte samples were soaked in the tracer
solutions, and incubated for one hour at 38°C. The
active transport rate was calculated from the difference
in influx rate between a solution containing ouabain
and a solution without ouabain. The passive transport
rate was obtained from erythrocyte samples soaked ina solution containing ouabain.
Figure 1 shows the changes in the Rb and K influx rates in erythrocytes soaked in Rb tracer solution.
The active transport rates of K and Rb were 3 to 4
times higher than the passive transport rates. The
active transport rate of K decreased significantly as
the Rb concentration increased. The rubidium influx
rate matched the potassium influx rate when the Rb

172

35,000~G!

30,000,..
I~ 25,000-s 20,000 l

~

I

I

I

Rbtran';:'I - - - ToI8llnftux- + - Active"~..

I - - - Passive".

I·· '- ·· ··I .......... ..... .

1__~K -~~ftUX.... .. ActiveoPassiveii

15,000:::l

10.000

r

)(

~

I

:x:

i

5,000

f

.Cl

0::

0
lE·7

lE-6

I&-5

lE·4

lE·3

lE·2

lE·l

External Rb concentration (M)Fig. 1. Active and passive transport rate of rubidium andpotassium into erythrocytes, K concentration is 4 mM.

concentration equaled the K concentration (3 mM, 4
mM and 6 mM). Figure 2 shows the changes in the Cs
and K influx rates when the external tracer solution
contained Cs. The active transport rate of Cs wasvery low , and lower than the passive transport rate.
Potassium transport was not much influenced by Cs.
The potassium transport system doesn 't seem tomake a clear distinction between K and Rb. Hereafter, we plan to study the efflux rate of K, Rb and Cs
from erythrocytes.

i

35,000l 30,000 >~I· .. ·· -t-....

~ 20.000-.f . ..-t..

1

Passive

15,000

)(

:::l

..'"

5,000

'C

c:

(J

K transport•• > • Total Influx... \)... Active~ 10,000~:x:

Actrve--.- Passive

---+-

"

~ 25,000~

Cslransport- - - Total Influx,-. - , •... - --'" -. -. -. -. -. +- 40

IE, lOo1--o--o----O!!!!!!!!!!!!!!!!!!!~~~F~- .:lE·9lE·S . IE·7

IE·6

IE·5

lE·4

lE·3

IE·2

I ·)

External Cs concentration (M)Fig. 2. Active and passive transport rate of cesium andpotassium into erythrocytes . K concentration is 4 mM.

References
1) Mertz W.: Trace Elements in Human and Animal Nutrition, 5 ed., Academic Press (1986).
2) Follis R. H.: Am. J. Physio l. , 138 , 246 (1973).

RIKEN Accel. Prog. Rep. 29 (1996)

Translocation of Radionuclides from Plant Leaf Surfaces
T. Watanabe, K. Matsumoto, S. Ambe, and 1. Yamaguchi
The outermost surfaces of the aerial parts of growing
plants are usually covered with cuticle which protects
the plant against invasion by microbes and against
non-specific penetration of foreign substances.
In
this study, we investigated the transcuticular uptake
and translocation patterns of various radio nuclides inplants. Ten p,l of an aqueous solution containing themultitracer generated from Au and 137 Cs, which is deficient in the multitracer, was applied to the uppersurface of the 2nd leaf of the Komatsuna plant (Brassica Rape var. pervidis cv. Seisen) and the mugwort at
the 5th leaf stage. The plants were then grown for 15
days at 25 °C and 70% RH under the illumination of
artificial solar light.
The uptake and translocation of the radionuclides
throughout the plant were periodically assayed by examinating the radioactivity of the surface residue, of
the cuticle layer beneath the applied water droplet ,of the leaf area outside the site of the applied water
droplet , of the other aerial parts of the plant , and ofroot. The radionuclides in the various samples weredetected by a Ge detector.

Most of the applied radionuclides were absorbed
into the cuticle layer under the applied site, and thentranslocated through the cuticle to the inner tissue,and eventually to the other leaves, stems and roots.
Figure 1 illustrates the time course of the uptake andtranslocation of Rb throughout the Komatsuna plant.
However, the distribution and accumulation depends
upon the characteristics of each radionuclide as demonstrated in Table 1.

;;

.

10

15

Incubation (days)

Fig. 1. Time course of the translocation of Rb in the Komatsuna plant (cv. Seisen) • Residue on leaf surface,• Penetration into cuticle, ~ Accumulation in the leaf
area outside the applied site, 0 Accumulation in theleaves and stem other than the treated leaf, 0 Root.

Table 1. Distribution of radionuclides in Komatsuna and Mugwort 15 days after application.

Radionuclide

Ca
Te

Residue on leal surCace

Penetration Into cuticle

(%)

(%)

Komatsuna

I Mugwort

98
97

100

Be

Ir

40
68
87
19

Mn

72

As

8
55
50
77
74
76
11

V

Zn

Ce

Sr

Rh
Ba
Eu
Gd

Pt

Re
Co
Rb

Cs

55
2
4

96

78
53
73
79
49
52
52
64
45
85
85
43
18
34
47
3

Komatsuna I MU2Wort

2
3

60
32
13
81
11
85
29
20
9
22
20
71

4
5
31

Accumulation In thetreated leal outside
the appUed site (%)
Komatsuna I MU2Wort

Accumulation In the
non-treated leaves
and stem (%)
Komatsuna I MU2Wort

Root(%)
Komatsuna

I Mugwort

5
20
20

19
21
18

4
22
47
27
21
51
23
33
24

47
15
15
57
33
31
9
28

From these results, one can discern a patternof transcuticular uptake and translocation common
to the two plants.
Ca and Te remained on theleaf surfaces, without being absorbed into cuticle,
Co, Rb and Cs were easily absorbed and thentranslocated and distributed to every part of theplant , and the others such as Be, Cr , Zn, Ce,
Eu, Gd, Ir, and Pt tended to remain in the region close to the site of its application. These pat-

17
7
16
30
14
4
5
18

25
15
10
8

49
16
14
19

6
10
22

20
59
26

10
13
29

terns indicate the existence of mechanisms for selective
transcuticular uptake, translocation and distributionof radio nuclides within plant tissues. 1)
References
1) T. Watanabe et al.: Proc. 32th Ann. Meet. on Radioisotopes in the Physical Sciences and Industries, Tokyo,
July, p. 129 (1995) .

173

5. Instrumentation

RIKEN Accel. Prog. Rep. 29 (1996)

Computer Environment around the Accelerator Facility
T. Ichihara, Y. Watanabe, and A. Yoshida
A general description of the data acquisition system at the RIKEN accelerator research facility can befound elsewhere. 1 ) In this report, we will describe therecent improvement of the system.
(1) On-line data acquisition system
Currently, eight Micro VAX's are used for on-line experiments at the RIKEN accelerator research facility.
The node names and locations are as follows:
RIKMVl::RIKMV2::RIKMV3::RIKMV4::RIPSVX::
SMART::
SMARTF::RIKLV2::

Micro VAX II (IF)Micro VAX II (B2F E3)
Micro VAX II (Linac)
Micro VAX II (B2F RIPS)VAX 4000 (B2F RIPS)VAX Station 3520 (B2F SMART)VAX Server 3300 (B2F SMART)VAX Station 3100 M76 (IF)Independent measurements and counter tests can be
performed without interference. The current version of
the data-taking program supports the CAMAC multicrate parallel-readout using multi-Jll 's (starbursts).
The throughput of the data acquisition is increasedby using these parallel readout features. Digital audio
tape (DAT) units of 2 GB capacity are used for the
standard on-line data recording.
(2) Off-line data processing system-l
The following Alpha/VMS and VAX/VMS workstations are available for the off-line data analysis and forgeneral purpose calculations.
RIKAXP::
RIKAXl::RIKAX2::RIKAX3::RIKAX4::RIKAX5::RIKAX6::RIKAX7::
RIKEN::RIKVAX::RIKVSO::RIKVS2::RIKVS3::
RIK835::RIKLVl::RIKLV2::home machine for the experimental user and also for aboot server. Seven Alpha workstations and seven VAX
workstations are used for the data analysis, etc. Theses
computers are connected by LAVC (Local Area VAX
Clusters) via the FDDI or ethernet. They are also
connected to the HEPnet (D ECnet ) and TISN and
STA/IM Internet (IP /DECnet) and cab be reachedfrom all over the world.
(3) Off-line data processing system-2
Following FACOM VPP 500 Massive Parallel computers and DEC OSF /1 server and workstation groups
have been also used for the off-line data analysis , simulations and theoretical calculation.
FACOM VPP 500 (RIKEN computation center)DEC 7000 (OSF /1) (RIKEN computation center)
These computers are connected to the Local Area
Network(LAN) via the FDDI using TCP /IP protocols.
(4) Wide area computer network
The RIKEN accelerator research facility is connected to the world-wide network ofHEPnet (High Energy Physics NETwork) / SPAN (Space Physics Analysis Network) as Area 40, which is a part of the DECnet
Internet , and to the TISN and STA/IMnet which is apart of "the internet". In order to support these wide
area network connections, following five leased lines areused.

1.5 Mbps to STA/IMnet
Alpha server 5/250 (Ring IF)
512 kbps to TISN Tokyo NOC hub
DEC 3000-400 (Ring IF)
64 kbps to KEK , Tsukuba
DEC 3000-400 (Ring IF)
9.6 kbps to Tokyo Institute of Technology
DEC 3000-400 (Ring 2F)(5) Address of the electric-mailDEC 3000-300 (Linac lab.)
The address of the electric-mail for a general user
DEC 3000-300 (Atomic lab.)of the RIKEN accelerator research facility is described
DEC 3000-300 (Ring, nuclear theory)
as follows, where the userid should be replaced by a
DEC 3000-300 (Radiation lab.)(virtual node name of the VAX cluster) proper name.
VAX-6610 (VAX boot server)(Internet)
VAX Station 4000-60 (Ring IF)
USERID@RIKAXP.RIKEN.GO.JP
VAX Station 4000-60 (Ring 2F)(HEPnet /D ECnet)
VAX Station 4000-60 (Ring IF)
RIKAXP::USERID(or 41823::USERID)
VAX Station 4000-60 (Radiation lab.)
VAX Station 3100 M76 (Linac Lab.)VAX Station 3100 M76 (Linac Lab.)
References

Alpha server 5/250 consists of a dual CPU and a
512 MB memory and has been newly installed as a1) T. Ichihara et al.: IEEE Transaction on Nuclear Science, 36-5 , 1628 (1989).

175

RIKEN Accel. Prog. Rep. 29 (1996)

Data Acquisition System for Segment-Ge Detector
T. Morikawa, Y. Gono, M. Shibata, T. Maeda, K. Miyazaki, T. Kishida,
E. Ideguchi, and M. Ishihara
A new data acquisition system has been developed
for a counter telescope of Ge detectors. 1 ,2) The telescope consists of a segmented .6.E detector and a clover
detector. The .6.E detector consists of twenty-five pixels. It has individual cathode outputs and a common
anode output, while the clover detector has four outputs. The energy and timing signals are handled separately, which gives a total number of sixty signals. For
the design of the acquisition system, much effort has
been paid to reduce the number of electronic modules
such as ADC's necessary for these signals. A block
diagram of the present system is given in Fig. 1.

Go

~
Q

C

0

F

g,....

Go

::!E

~

0

E

0
0
0

c(

E

I
:::i

c(

UNIX onSUN
Workstation

Fig. 1. A block diagram of the data acquisition system.

All energy signals are amplified separately by the integrated amplifiers,2) and are fed into the multiplexer
specially designed for the present system. The multiplexer has thirty linear energy inputs, thirty logic 'ID'
inputs, one strobe input and one reset input. The logic'AND' between the strobe signal and the logic ID signals gives the valid channels to be handled. Thus, thethirty energy signals are multiplexed into four inputsof the ORTEC ADC 413A; the average number of si-

176

multaneous hits has been estimated to be less thanfour. The separately handled CFD outputs are usedas the ID inputs for the multiplexer. The CFD timing
signals are also measured by LeCroy TFC 4303 's and
FERA ADC 4300B 's, which gives the ID for the dataof ADC 413A.
The crate controller CC7000 made of TOYO TECHNICA company interfaces the CAMAC modules,
such as ORTEC 413A and LeCroy 4300B , and an
MSDOS-based data-taking program running on an
NEC PC9801. A trigger for the acquisition system
is given by a LAM generator, which accepts a TTL
signal for a valid event and gives a level to the LAM
line in the station. Once the LAM is detected, the program sends a series of CAMAC commands to CC7000
to read the digitized data from the modules. By thedata- taking program, the data are stored in the buffer
allocated on a PC memory. When the buffer becomesfull or high-water, the data is transferred to the disk
file of the SUN workstation which is accessible fromthe PC by NFS mount via TCP lIP. The maximum
data transfer rate is about 50- 60 kbytes/sec.
On the SUN workstation, an online sorting programis waiting for the arrival of the data. When the data
newly arrives , the program starts sorting and updates
the histograms. The histograms can be analyzed online by using the program GF2. 3)

References
1) E. Ideguchi et al.: RIKEN A ccel. Prog. Rep., 27 , 121(1993).
2) Y. Gono et al.: ibid. , 28, 122 (1995).
3) D. C. Radford: private communication.

RIKEN Accel. Prog. Rep. 29 (1996)

Development of an On-line Laser Ion Source Using Resonance
Ionization in an Ion Guide Chamber at RIKEN GARIS/IGISOL
M. Hies, T. Ariga, T. T. Inamura, W. G. Jin, K. Morita, T. Murayama, Y. Pu, and M. Wakasugi
At the RIKEN GARIS-IGISOL facility a new on-line
Laser Ion Source (LIS) system has been constructed.
The nuclear reaction products are separated from theprimary beam by using the gas filled recoil separator
GARIS I ) (see Fig. 1). The reaction products are implanted through a thin entrance window of 5 }-lm Al ina thermalization chamber (see Fig. 1), where the highly
charged recoils are thermalized and neutralized in thebuffergas, typically a noble gas like helium or argon.
The not neutralized single charged recoil ions are removed with the help of an electric field towards an electrode inside the thermalization chamber. The remaining recoil atoms are transported with the help of thehelium gas flow to the laser ionization chamber, where
the atoms are ionized through incident pulsed laser
beams via a multi-step ionization scheme. The ionscreated via resonance ionization are now flushed out
with the help of the gas flow through a nozzle and aretransported via a SPIG (sextupole ion beam guide)2)
and a skimmer towards the extraction and acceleration electrodes. After passing through the dipole magnet the mass separated and element selected secondary
radioactive beam can be transported to a detector ora further experimental set-up . The new three chamber set-up (thermalization, laser ionization and nozzle
chamber) is constructed in modular design to adapt
to experimental conditions and to have good testing
possibilities in off-line experiments.

GARIS

Cyclotron
HI beamentrance
foil

IGISOLHighlychargedrecoils=::>Fig. 1. On-line experimental setup.

First off-line experiments have been performed using stable hafnium. The atoms are produced via laser
ablation when focussing a weak dye laser beam (0.3mJ/pulse) on a Hf-plate in the thermalization chamber. The atoms are ionized via the two-col our-twostep excitation scheme as cited in Ref. 3. In Fig. 2 theion count rate at the channeltron detector is shown

100
Mass Calibration
176 177 178179

174

80

180

! !1! !

!

Laser 1on resonance78.224nm

60
(j)
0..

.£
<J)

C
:::l

0
C)

40

20

3.32

3.34

3.36

3.38

3.40

D-Magnet Input Value

Fig. 2. Ion count rate at the detector position as a function of the D-magnet-current on laser resonance and off
resonance. The arrows are marking the stable Hf isotope mass abundance. The laser repetition rate was set
to 100 Hz and the second laser wavelength was fixed toan autoionizing transition at >'2=356.405 nm.

as a function of the IGISOL-D-magnet current for theon resonance (AI =368.224 nm) and the off resonancecase (AI =370.000 nm). The enhancement factor of ionswith the mass 180 through laser ionization is about 15.
The total transportation time was measured to 60 ms.
However, only 1 % of the Hf ions produced via laser
ionization survive during the transportation with thegas flow towards the nozzle. The rest forms molecules
like HfHxOy after collisions with impurities in the gas.
To enhance the signal a further improvement in the gas
purification and the vacuum conditions of the IGISOL
chamber have to be done.
Beside using the new system as an ion source to provide highly selected radioactive ion beams , also laser
spectroscopy experiments can be carried out by using
the resonance ionization spectroscopy (RIS) to measure isotope shift and hyperfine structure of nuclei farfrom stability and determine their nuclear radii andnuclear moments. 4 )References
1) K . Morita et al.: Nucl. Instrum. Methods Phys. Res.,
B70, 220 (1992).
2) H . J. Xu et al.: ibid. , A33 , 274 (1993).
3) M . Hies et al.: This report, p. 198.
4) E. W . Otten: Treatise on HI- Sci., 8 , 517 (1989).

177

RIKEN Accel. Prog. Rep. 29 (1996)

Operation and Status of the RIKEN EBIS (REBIS)
N. Watanabe, S. Kravis,* Y. Awaya, T. M. Kojima, K. Okuno, and M. Oura
Electron Beam Ion Source (EBIS) is widely used
to study the physics of highly charged ions. The
highly charged ions are formed by successive ionization by electron impact while ions are trapped inside
the source using electric field which is produced radially by the space charge of the electron beam andaxially by the applied dc potential. The EBIS hasadvantages that the pulsed ion beam operation which
creates a higher charge state effectively, is available
and the delivered ion beam has a low emittance anda low energy spread which enables one to carry out ahigh resolution experiment. We have constructed andoperated a mini-size RIKEN EBIS (REBIS) based on
Okuno's mini-EBIS.l,2) This report presents the status
of REBIS and some spectra obtained.
The REBIS is much smaller than typical EBISes
which require liquid He for a superconducting solenoid
and a residual gas trap. Adoption of the liquid nitrogen cooled solenoid, instead of the superconducting
one, which can make enough magnetic field to pro(a)

Ar°+

:12

duce bare ions with moderate Z species, enables us
to reduce the size of REBIS. The existence of residual gas essentially restricts the performance of EBIS
since the charge states of produced ions are easily decreased by the charge exchange with neutral atoms.
In addition, since sample gas is normally introduced
into the ionization region continuously, electron capture from neutral sample gas becomes a serious problem specially in the higher charge states. The REBIS
is evacuated by two turbo molecular pumps and thenon-evaporative getter (NEG) pump. The pumping
system with an LN2 trap can produce a vacuum inthe low 10- 10 torr range where the effect of charge
exchange with residual gas is very small. Moreover,
applying pulsed sample gas, the charge exchange withthat was minimized and consequently the production
rate of highly charged ions was significantly improved.
Ions are extracted from a trap region after a given
confinement time and charge analyzed by the time offlight (TOF) method. Figure 1 shows typical charge(b)

Tc=400ms

Tc=400ms

IU~ ).tL
12

i12

Tc=2s

Ul~tl

Time of flight (arb. units)

Tc=2s~ 1~1~~~
Time of flight (arb. units)

Fig. 1. TOF spectra for the continuous gas (a) and the pulsed gas
operation (b), respectively. Tc represents a confinement time.

distribut.ions for Ar ions extracted by 2 kV. The
electron-beam current is normally only 5 mAo One cansee that for the pulsed gas operation, the charge distribution shifts to higher states and a relative intensityof Ar 16 + increases with the confinement time. On theother hand, for the continuous gas operation Ar 16 +is not observable. Charge distribution for the continuous gas operation is almost saturated after 400msec confinement, that is, the distribution does notchange anymore in contrast to the pulsed gas case.
The ion intensity is typically from 10 pA to 30 pA for
Department of Physics, Kansas State University

178

Arl1+ for both the continuous and pulsed gas with 1sec confinement. lop current for the each charge statestrongly depends on the operation condition, particularly the condition of the electron beam. Further tuning and characterizing the REBIS will be done.

References
1) K. Okuno et al.: Nucl. Instrum. Methods Phys. Res.,
B53 , 387 (1991).
2) S. Kravis et al.: Rev. Sci. Instrum., 65 , 1066 (1994).

RIKEN Accel. Prog. Rep. 29 (1996)

Development of the Deuteron POLarimeter DPOL
S. Ishida, Y. Satou, H . Okamura, N. Sakamoto, H. Otsu, T. Uesaka, T. Wakasa, S. Fujita,
T. Ohnishi, T. Nonaka, H. Sakai, T. Ichihara, T. Niizeki , N. Nishimori, and K. Hatanaka
We reported last year the construction and the firsttest experiment of a new vector and tensor Deuteron
POLarimeter DPOL.1) In this year we slightly modified the configuration of DPOL to improve the performance.
A CH 2 block with 2.5 cm thickness was equipped
as a scatterer to improve double scattering efficiency
in addition to existing two plastic active scatterers described in Ref. 1. Thicknesses of the iron absorbersof the calorimeters CM1 and CM2 were also changed
from 1.80 to 1.35 cm to cope with the increase of energy losses of particles in the thickened scatterer.
DPOL will mainly be used for spin transfer measurements in deuteron inelastic reactions at excitationenergies up to 40 MeV with a deuteron polarized beamof 270 MeV. Therefore we have to know effective an- .
alyzing powers and efficiency of DPOL in the energy
region from 230 to 270 Me V.
The calibration experiment was performed in thisMarch with a 270 Me V polarized deuteron beam extracted from the RIKEN Ring Cyclotron. DPOL wasinstalled in the second focal plane of the spectrograph
SMART. The beam swinger magnet of SMART was set
at 0° and the measurement was performed directly inthe faint beam of about 5 x 10 4 deuterons/sec without any scattering in a primary target. DPOL wasalso calibrated at energies of 230 and 250 Me V. Such
deuteron beams were obtained by using Al energydegraders placed in the SMART target chamber. The
depolarization effect by degrading the beam energy is

expected to be negligibly small. 2)
Three combinations of the beam polarizations wereused in this experiment and their ideal values of vector
and tensor polarizations are (pz,pzz) = (0, -2), (0,1)
and (2/3,0), respectively.3) The polarization axis wascontrolled with the Wien filter located at downstreamof the ion source. The beam polarization was monitored by using the d + p scattering at 270 Me V andtypically 60- 65% polarization of the ideal value wasobtained throughout the experiment.
The cross sections corresponding to these polarized
beams are written as follows :(J'(B , ¢) = (J'o(B) x{I + 2itlliTll(B)cos¢ + t2oT20(B)+ 2t21 T21 (B) cos ¢ + 2t22T22 (B) cos 2¢},where itll ' t 20 , t21 and t22 are beam polarizations andiT11 , T 20 , T21 and T22 are effective analyzing powersof DPOL. Using the (J'(B, ¢) values corresponding to
the polarized beams and the (J'o (B) value obtained byan unpolarized beam, 'we can get all components ofanalyzing powers. The double scattering efficiency was
also determined.
Figure 1 shows the preliminary result of the effective
analyzing powers for the 12C(d, do) reaction at Ed =270 MeV. Large iTll values are obtained. 4 ) The samedata for the 1H(d, 2He) reaction are shown in Fig. 2.
In this reaction T 20 and T22 have large values. 5 ) Thus
DPOL can determine vector and tensor polarizations
simultaneously by using the single polarimeter-system.

1.0
0.4

0.4

0.8

0 .2

0 .2

0.0

0.0

0.0

-0.2

-0.2

-0.2

-0.4

-0.4

0.6
0.4
0.2
5

10

15

0.4

0.2

20

0

- 0.4
0

5

10

15

20

0.4

0 .4

0.4

0.2

0.2

0 .2

0 .2

0.0

0.0

0 .0

0.0

-0 .2

-0.2

-0.2

-0.2

-0.4

-0.4
0

5

10

15

20

5

10

15

20

5

10

15

20

0

5

10

15

20

0.4

- 0 .4
0

0

-0.4
0

5

10

15

20

8 1ab (deg.)

8 1ab (deg.)

Fig. 1. Preliminary results of the effective analyzing powers of DPOL at Ed = 270 MeV for the 12C(d, do) reaction.

Fig. 2. The same as Fig. 1 for the 1 H(d,2He) reaction.
The excitation energy range of the pp pair is 0-4 MeV.

179

The double scattering efficiency is 1.2 x 10- 2 for the
12C(d, do) reaction and 0.9 x 10- 3 for the 1 H(d, 2He)
reaction.
Energy dependence of the performances of DPOL
was also tested. For example, iTll values for the
12C(d, do) reaction at Ed = 230 , 250 and 270 MeV
are shown in Fig. 3. This result shows the stable performance of DPOL over an energy range from 230 to
270 MeV.

iT 11 for 12C(d,do) events

1.0
0.6

270 MeV

0.6
0.4
0.2
0.0

~~~~~~t++
~

~~~~~

0

5

~

10

15

References
1) S. Ishida et al.: RIKEN Accel. Prog. Rep. , 28, 125(1995) ; AlP Conf. Proc. , 343, 182 (1995).
2) S. Kato et al.: Nucl. Instrum. Methods Phys. Res. ,

0.4
0.2
5

Fig.

3.

10

15

20
8 1ab (deg .)

5

10

15

20

Energy dependence of the iTll values for the

12C(d, do) reaction.

180

20
1.0
0.6
0.6

1.0
0.6
0.6
0.4
0.2

A238, 453 (1985).
3) H. Okamura et al.: RIKEN Accel. Prog. Rep. , 28 , 148(1995) .
4) B. Bonin et al.: Nucl. Instrum. M ethods Phys. Res. ,A288, 389 (1990).
5) S. Kox et al.: ibid., A346 , 527 (1994).

RIKEN Accel. Prog. Rep. 29 (1996)

Development of Polarized Xe Solid as a Means to Produce Spin
Polarization in Stopped Unstable Nuclei
H. Sato, K. Mochinaga, M. Adachi, and K. Asahi
Recent results l - 4 ) obtained at RIKEN Ring Cyclotron demonstrated that measurements of nuclear
moments provide useful information on the microscopic structure of nuclei far from stability. In such
experiments, producing spin polarization in the objective nuclei is a key technical ingredient. We are developing a new method to produce the polarization,
which comprises the implantation of unstable nuclei ina highly polarized stopper and the subsequent transfer of the host nuclear polarization to them throughdipole-dipole interaction. For the host material, we
employ a 129Xe solid for which a large spin polarization and a long relaxation time can be attained. 5 ) We
started the study to polarize 129Xe gas last year.
The 129Xe nuclear spin is polarized by spin exchangewith an optically polarized Rb atom. A cylindricalglass cell 4 cm long and 2.2 cm in diameter is filledwith a natural Xe gas of a partial pressure PXe, an N2
gas of 100 Torr, and a small amount of Rb vapor. The
cell is illuminated by a circularly polarized light froma 2 W Ti:sapphire laser. Details of the principle ofthe method and of our apparatus have been described
previously.6)
We studied the pressure dependence of the Xe polarization PXe by using several cells with different Xe
gas pressures. The result is shown by dots in Fig. 1.
A polarization as large as PXe = 57.4% is obtained at
PXe = 10 Torr. P X e decreases with increasing PXe, but
up to PXe = 200 Torr which amounts to the numberof Xe atoms of 1.0 x 10 20 , the polarization stays larger
than 9%. In Fig. 1 are also shown theoretical curves
which are derived from the rate equations describing
the transfer of polarization among the laser photons,
Rb atoms, Xe nuclei and a cell wall. 7 ) The theoreticalPXe depends on the wall relaxation time T w' For thecells used in this experiment, Tw ::::::; 5 min was obtained
from the 129Xe NMR signal amplitude measured as afunction of time after the cell was cooled to room temperature. As shown in Fig. 1, the curve for Tw = 5 min
indeed reproduces the data fairly well. Also, the curvesindicate that a longer wall relaxation time will allow
realization of a stopper with enhanced polarization andnumber of atoms. We are testing new glass cells whose6050...-..

40~

e.....
Q)

30

X
Q..
20

10

0
0

100

200

300

400

500

600

700

Xe pressure (Torr)
Fig. 1. Pressure dependence of PXe. The experimental
data are shown by dots. Also shown are the theo:z:eticalcarves obtained for several T w.

inner surfaces are coated by dichlorodimethylsilane,
with which Twas long as 30 min is reported. 8 )For a stopper to polarize implanted nuclei, a solid
has to be produced from thus obtained polarized gasof Xe. A magnet to produce a 0.5 T field and an NMR
system operated under this field were installed. This
field is needed in order to lengthen the spin-lattice relaxation time of Xe in a solid phase. In order to solidify Xe gas, the cell is moved from the optical pumping
setup to the high field region where the liquid N 2 bathto cool the cell is installed. We are investigating thecondition for the adiabatic transport of the Xe sample
so that the initial polarization is maintained during
this process.
References
1) H. Okuno et al.: Phys. Lett., B354, 41 (1995).
2) H. Izumi et al.: ibid., B366, 51 (1996).
3) H. Deno et al.: submitted to Phys. Rev. , C.
4) K. Asahi et al.: Nucl. Phys. , A588, 135c (1995).
5) M. Gatzke et al.: Phys. Rev. Lett., 70 , 690 (1993).
6) H. Sato et al.: RIKEN Accel. Prog. Rep., 28, 128 (1995).
7) G. D. Cates et al.: Phys. Rev., A45, 4631 (1992).
8) X. Zeng et al.: Phys. Lett., A96 , 191 (1983).

181

RIKEN Accel. Prog. Rep. 29 (1996)

Development of the Detector for Sub-MeV /3-Delayed Neutron
K. Yoneda, N. Aoi, H. Miyatake, H. Ogawa, Y. Yamamoto, E. Ideguchi, T. Kishida, T. Nakamura,
M. Notani, H. Sakurai, T. Teranishi, S. S. Yamamoto, Y. Watanabe, A. Yoshida, and M. Ishihara
We developed a new type of a neutron detector in order to measure neutrons with energies as low as about
100 keY. The low-energy neutron detection is often required in studying structures of very neutron-rich nuclei via ,8-decay with neutron emission.
In our previous experiment on the ,8-decay of neutron drip-line nuclei 14Be,1) a prominent peak wasfound it the low neutron energy of 283 keY in the
delayed:..neutron spectrum. However, we could not deduce the branching ratio with sufficient accuracy due
to the limitation of the low-energy neutron detection.
The objective of developing new neutron detectors is
primarily to determine precisely the branching ratio ofthe ,8-decay of 14Be, and to apply the detectors to thesimilar cases in the future experiments.
The neutron detector used in the previous experiment was a plastic scintillator BC408 which has arectangular shape with size of 6 cm(H) x 110 cm(W)x 6 cm(D) . We set the threshold at about 20 keY
in electron equivalent energy, corresponding to about
200 keY for neutron energy. The threshold was calibrated with the energy of Compton edge of 662 ke V')'-ray from a 137 Cs source. The detection efficiency
for 283 ke V neutron was only about 10%, and furthermore, the time-of-flight (TOF) spectrum of the delayed
neutron might be distorted due to the rapidly changing
function of neutron efficiency toward the lower neutronenergy. These difficulties were attributed to the factthat the threshold was very close to the relevant peakenergy. Further amplification of the light output bya photomultiplier tube (PMT) or by other electronic
amplifying circuits cannot, by itself, lower the threshold, because of the fatal lack of initial photoelectrons
in the PMT. In the measurement of 283 ke V neutron,
the number of scitillation photons that could reach thephotocathode of the PMT was found to be less than
20 due to the small number of original photons andthe poor transmission efficiency (about 8%) of the detector, and this implies that less than 5 photoelectrons
could be emitted from the photocathode of the PMT.
The only way to reduce the threshold is to increase
the photon numbers impinging on the photocathode,which may be realized by making the detector with ashorter light path and thereby improving the transmission efficiency in the plastic scintillator.
We produced a plastic scintillation detector with sizeof 30.0 cm(H) x 4.5 cm(W) x 2.5 cm(D). This short sizeof the detector enables us to obtain larger transmission
efficiency, approximately 25%. In the case of detecting

182

283 ke V neutron, about 70 scintillation photons may
reach the photocathode and about 20 photoelectrons
would be released from the photocathode, which would
be enough for the 283 keY neutron measurement.
On the other hand, when we actually use this detector, the solid angle and the time resolution may cause
a problem. We can overcome the decrease of solid angle due to the small size of this detector by making theneutron flight path shorter. However, a shorter flightpath may cause worse resolution. As the optimum condition both for the solid angle and for the resolution,
we set the neutron flight path 50 cm, one-fourth of theprevious setup (2 .0 m) so as to make the total solid
angle to be 4.2% of 47T, which is comparable to that in
the previous experiment. As for the time resolution,in the case of detecting 283 ke V neutron, such a low
energy allows us to obtain sufficiently long TOF evenfor the short flight path of 50 cm. In fact, the TOF
is 68.3 ns for 283 ke V neutron and the time resolution
caused by the thickness of the detector is about 1.0 ns ,corresponding to 1.5% for momentum resolution. Thisvalue is comparable to the resolution of the detectors
which make the start signal of the TOF.
We applied this new neutron detector to the measurement of ,6-decay of 14Be 2 ) and 11 Li. The TOF
spectrum of the ,8-delayed neutron of 14Be is presented
in the Ref. 2. The detection efficiency for 283 ke V
neutron detection was estimated to be about 50%
from comparison between spectra of ,6-ray and neutron
TOF, from each of which we can deduce the branchingratio. We were able to set the threshold at about 2 ke V
in electron equivalent energy (a few tens ke V for neutron energy), which was calibrated with the low energy
X-ray from a 133 Ba source and a 241 Am source. Sucha low threshold enabled us to measure much lower energy neutrons, such as the ,6-delayed neutron of about
80 ke V from 11 Li, which was not observed with theprevious detector. The time resolution was deduced
to be about 1.5 ns from the width of the prompt ')'ray peak in the spectrum. This resolution is to be
improved by the further analysis. The peak width ofa 283 keY neutron from 14Be was found to be about
4 ns, much larger than the time resolution, implyingthat the resolution of the new detector is good enoughto deduce the natural width of this state.
References
1) N. Aoi et al.: RIKEN Accel. Prog. Rep., 28 , 38 (1995).
2) N. Aoi et al.: This report, p. 67.

RIKEN Accel. Prog. Rep. 29 (1996)

Slew Correction for Timing Signals from NaI(TI) Scintillators
T. Kikuchi, T. Motobayashi, S. Shimoura, and H. Murakami
Leading-edge discrimination is widely used to generate the timing logic signals, especially for fast signals
from plastic scintillators etc. However, in using thistype of discriminators, one encounters a famous walkeffect. It is variation of the delay time of the output
signals according to the amplitude of the incoming signal, which is caused by its finite rise time. So when thediscriminators are used in coincidence experiments or
TOF measurements, it is necessary to correct this effect in off-line analysis (slew correction) to improve thetiming resolution.
For plastic scintillators, a simple method is often
used for the slew correction,1,2) that is tlt = G / VA.,
where tlt is the amount of the correction, A is the amplitude of the pulse and G is an adjustable parameter.
An additional way is proposed 2) to take account of thepulse shape of the inputs directly. However, the authors concluded that it showed little difference fromthe former method in case of plastic scintillators.
We studied the walk effect for NaI(TI) scintillatorsthat gave slower signals than those of plastic scintillators. The results showed quite different features fromthe case of plastics, suggesting strong pulse shape dependence. We propose another method for the slew
correction from the results.
We used a NaI(TI) scintillator with a 6 x 6 x 12 cm 3
volume and the pulse shape was measured. It could bett
expressed as V(t) = Vo( e- Il - e- I2 ), with t1=230(ns)and t2=40(ns). For the triggering of leading-edge discriminators, the rise time t2 is essentially importantand the decay time is not. Another effect to be considered is the gaussian-like smearing that is caused byprocesses in the photo-tube and following circuits. By
referring to the formula for plastic scintillators,2) we
can write down the effective pulse shape of N aI(TI) as,(1)

where A is the amplitude of the pulse, Ath is the amplitude corresponding to the threshold, T = t rise /2.6,
and tris e is the rise time of the pulse that is 40 ns inthis case. Note that it gives the same correction as thatwith tlt = G / VA. at the limit of t « T. In the present
slew correction, we improved further this formulation
by replacing the second power in Eqn. (1) with the xth power as a parameter. As a result , we got a new
formula of slew correction as ,(2)
The power x should be adjusted for a given thresholdlevel.

We applied this equation for the slew correction of
the NaI(TI) scintillators. The difference of the timing from the NaI(TI) scintillator and a plastic scintillator was measured by detecting two ~ rays from a
60Co source in coincidence. Assuming constant timing
for the plastic scintillator, we extracted the amount ofwalk for NaI(TI) with some different settings of thethreshold A th . Examples of the results are shown by
the two-dimensional spectrums in Fig. 1. The dots
represent averaged time difference deduced from theexperimental data at each amplitude, and the solid
curves represent the slew correction using Eqn. (2).
Adjusted values for the parameter x are 0.2 and 0.6 forAmax lAth values of 60 and 5, respectively. The results
show good agreements with the data in a wide range of
amplitude. We tried also the method At = G I JA for
these data, which agreed only with the setting of very
low thresholds. For the data of Fig. 1 (a), the achieved
time resolution was much the same with both methods.
However, for the data of Fig. 1 (b), the achieved time
resolution was 5.5(ns) with the method At = GlVA.,
whereas that was 4.5(ns) with Eqn. (2).

00-

60

~

v
.5
.....

50
40
30
60

00-

50

~

v
40
.5
.....
30
0

100

200

300

400

ADC(ch)Fig. 1. Time difference between NaI(TI) and plastic scintillators plotted versus ADC channel in cases of (a) alower threshold and (b) a higher threshold.

References
1) T. Kobayashi and T. Sugitate: Nucl. Instrum. Methods
Phys. Res., A287, 389 (1990).
2) W. Braunschweig et al.: Nucl. Instrum. Methods., 134,
261 (1976).

183

RIKEN Accel. Prog. Rep. 29 (1996)

NaI(TI) Detector Assembly for Low Intensity Radiation (DALI)
T. Nishio, T. Motobayasi, K. Ieki, Y. Ando, H. Murakami, Y. Yanagisawa, Y. Iwata, T. Kikuchi,
T. Uchibori, H. Fujiwara, T. Minemura, M . Suzuki, and S. Shimoura
A detector array DALI (Detector Assembly for Low
Intensity radiation) has been constructed for measurements of, ray from nuclear reactions with low yield. It
consists of sixty four NaI(TI) scintillators and six plastic scintillator plates. To achieve the high efficiency for, rays, the detector should cover a large solid angle.
An example of the geometry is shown in Fig. 1. The
volume of NaI(TI) scintillator is 6 x 6 x 12 cm 3. To
reduce background contained between spectra due tocosmic rays, plastic scintillators of 1 x 30 x 90 cm3

cosmic ray

beam

Sixty four NaI scintillators

were set on the top and bottom of the NaI(TI) scintillators as shown in the Fig. 1.
To gain fast signals suitable to trigger a fast discriminator, a timing filter amplifier (TFA) was developed.
It amplifies the slow signals from the NaI(TI) scintillator with a fixed gain and a fixed time constant of 22
ns. For the DALI setup, eight NIM-standard modules
with eight parallel TFA units were fabricated.
The DALI has been used in the Coulomb excitation experiments with radioactive beams of 50-70
MeV Inucleon for the 208Pbe 2Mg, 32Mg,)208Pb1) and
208Pb( 56 Ni, 56Ni,)208Pb2) reactions. The highly segmented structure of the DALI setup allows to correcta large Doppler shift caused by the fast (vic "'0.3)
production that emits , rays. The total detection
efficiency of the DALI for a full-energy peak was 20
and 9% for the 885 keV and 2.7 MeV, rays, respectively, which are of interest in the above two experiments. This efficiency is for the events where one of
the NaI(TI) scintillators used with the DALI absorbs
the entire , -ray energy. The setup was used also in
an expriment at Luvain-La-Neuve with a low energy(blow 1 MeV Inucleon) radioactive 13N beam. The 5.17
MeV, ray from the 1He 3 N, ,) 14 0 reaction was measured. The full-energy peak efficiency is estimated to
be arround 20%, if all possible combinations of energy
deposited among the NaI(TI) scinitillators are allowed.

Six Plastic scinitillators

References
Fig.!. The DALI setup by sixty four NaI scintillators andsix plastic scintillators.

1841) T. Motobayashi et al.: RIKEN Accel. Prog. Rep. , 28,
37 (1995); Phys. Lett., B346, 9 (1995).
2) Y . Yanagisawa et al.: This report, p. 76.

RIKEN Accel. Prog. Rep. 29 (1996)

Summing Amplifiers for Heavy-Nucleus Search Experiments
T. Uchibori, T. Motobayashi, H. Murakami, M. Kurokawa, K. Morita,
Y. Pu, T. Nomura, and Y. Tagaya
In experiments of heavy-nucleus search, a .detection
system with high energy- and position-resolution isnecessary to detect evaporation residues produced byfusion reactions. To identify the product, the energies
of its successive a decays are measured.
For this purpose a system with a position sensitive
detector has been developed 1 ) and used in the experiment of 40 Ar+ 232 Th reaction. 2 ) Since the charge division method is employed to measure the position
along a strip, signals from the two ends of the strip
should be analyzed. In the experiment, the two signals
are treated by two parallel amplifier systems independently and fed into peak-sensitive ADCs as shown in
Fig. 1.

The energy data are obtained by summing the two
ADC outputs. This method, however, has a problem at low energies. The peak-sensitive ADC takes amaximum voltage during the gate duration. For lowenergy a particles (below 1 MeV), this maximum canbe due to a large thermal noise instead of the true energy signal, resulting in a wrong energy-sum datum.
This thermal noise along the strip is mostly cancelled
by integrating the charge from the two ends. This isachieved by summing the two signals as shown in Fig.
2 before analysis by the ADCs, and correct sum-energy
signals are provided.
We developed an amplifier (SUM AMP) to realize

PSD (strip

SUMAm
ADC (energy)

left

right
ADC (posi tion )Fig. 1. The block diagram for a scheme without thesumming amplifier.
2.7kO

9100

Fig. 2. The block diagram for a scheme with the summing
amplifier.
4.7kO

2.2kO

Fig. 3. The circuit diagram of the summing amplifier.

this analogue sum. A schematic diagram is shown in
Fig. 3. By a variable resistance, fine adjustment of
the gain is possible. This reduced much the time tocalibrate all the channels for the 40 detector outputs.
We fabricated NIM one-span modules that contain 8chof the summing amplifier units.
Without the SUM AMP (Fig. 1), the energy resolution was measured to be 300-400 ke V FWHM atenergies lower than 1 Me V though it becomes 40-60
ke V at energies higher than 6 MeV where the a decays from heavy nuclei are expected. When the SUM
AMP is used (Fig. 2), the resolution in the low energy region was improved to about 100 keY. This

new system has been used in the 36 Ar+ 164 Er reaction
experiment. 3 ) The present development improved theperformance of the detection system especially for thea-decay escaped from the detector leaving a small energy signal.
References
1) M. Kurokawa et al.: Proc. Tours Symp. Nucl. Phys. II,
Tours, France, Sept. 1994, World Scientific, Singapore,p. 428 (1995).
2) M. Kurokawa et al.: This report, p. 44.
3) Y. Pu et al.: This report, p. 43.

185

RIKEN Accel. Prog. Rep. 29 (1996)

Test of a High-Rate MWDC for Heavy-Ion Detection
M. Yamagami , K. Miki, H. Utsunomiya, T. Yamagata, *1 S. Kubono ,M. H. Tanaka, Y. Matsuyama,*2 H. Sakurai, and T. Murakami*3
A high-rate coincident detection of Q and 12C is necessary for the study of Coulomb breakup of 16 0 at
the intermediate energy. 1) We have built a prototype
multi-wire drift chamber (MWDC) with the drift cellwidth of 5.0 mm in four planes (16 cm wide and 16
cm high) of X-X'-Y-Y' configuration. It was mounted
behind the end of the beam line and was tested withbeams of Q and 12C at 100 MeV/nucleon from the
HIMAC at the National Institute of Radiological Sciences (NIRS). The chamber was operated with 50%
He and 50% C 2H 6 mixture containing methylal as anadditive. Helium-base gas mixture, instead of argonbase, was used to reduce the b-ray contribution. We
investigated the dependence of anode pulse-height distribution on the operating high voltage , b-ray production, and the space charge effect with each beams.
The number of beam particles was counted with fast
signals from a plastic scintillator placed behind the
MWDC. It was kept well below 10 3 particles per beam
spill/cm(pps/cm) , spill time being 0.4 second , for thepulse height study and was increased up to 10 5 pps/cm
for studying the space charge effect.
Figure 1 shows pulse-height distributions of 12C atcathode voltage (V c) -1300 V. In this condition, theprobabilty of firing of the neighboring wire by b-rays
was about 25%. The most probable pulse height of Q
and 12 C vs V c (Fig. 2) and the space charge effect for

1200

I

r--

1000

I
I

:c

BOO

~

600

~

::
Jl

= 400

~

200
O ~~~~~~~~~~~~~- 1000-J JOO

-1200

-1300

-J400

·1500

Vc:H.V. (Cathode) [V]

Fig. 2. Most probable pulse height of C\' and 12C vs . V c.
2000+.--'==*='f---_

Vc=

:c
~

.:EOJ)

1000

==

Qj

-3

Q.

·1250V
400
10Count Rate [pps/cm]

50

Fig. 3. Space charge effect for 12C. The abscissas stands
for the count rate in units of counts per second per cm
for a wire.

-N

Vc= ·1300V

40

30
tl

'="

12C (Fig. 3) were presented. It was found that the
MWDC works stably at the rate higher than 1 x 10 3
counts per second per cm for a wire, and have no signof aging of wire after the test.

Q

U

20

10

o

500

1000

ISOO

2000

Channel No.

Fig. 1. Pulse-height distributions of 12C at cathode voltage(Vc) -1300 V. Signals of 12C (part C) are well separated from those of 8-rays occurred in neighboring cell
(part D). Part Sand N of the spectra are due to saturation of the signals and detector noises , respectively.

*1
*2
*3

186

Department of Physics , Konan University
Institute for Nuclear Study, University of Tokyo
National Institute of Radiological Science

References
1) H. Utsunomiya, Y. Hirabayashi, M. Hirai , T. Ichihara,
M. Kamimura, S. Kato, S. Kubono , T. Motobayashi, S.
Okabe, H. Sakurai, and M. Yamagami: Proc. of Tours
Symp. on Nucl. Physics II, H. Utsunomiya, M . Ohta,
J. Galin, and G. Miinzenberg (Eds.) , World Scientific
Publishing, Singapore, p. 126 (1995).

RIKEN Accel. Prog. Rep. 29 (1996)

Construction of a PPAC with High Position Resolution
H. Kumagai and K. Yoshida
A parallel plate avalanche counter (PPAC) with position resolution of less than 1 mm was developed asa focal-plane detector for the secondary beam separator RIPS.I) The existing PPAC was the one whose
cathode had a strip structure with a 2 mm pitch. Figure 1 shows the position spectrum of the PPAC whenthe electrode was irradiated uniformly by Q rays from
241 Am. The peaks seen in the figure correspond to thestrips on the cathode. This is because the charge arising from the avalanche is collected with a few strips
and hence, it is impossible to get the position resolution of less than 2 mm.

~OOO~----------------------------~

20000

E 15000
E

-~

C
:::l

8 10000
5000

3~~------------------------------~
·50

.

-40

·30

·20

·10

0

10

20

30

40

50

X (mm)

30000

Fig. 2. The same figure as Fig. 1 except for the PPAC
with 1 mm strips.

25000~ 20000~cg 15000
U
10000

5000

·50

-40

·30

·20

·10

10

20

30

40

50

X (mm)

Fig. 1. The position spectrum for the PPAC with 2 mm
strips uniformly irradiated by Q rays of 241 Am.

In order to improve the position resolution, three
types of PPACs with active areas of 50 x 50 mm 2 , 100 x
100 mm 2 , and 150 x 100 mm 2 were constructed with
an electrode with strips of 1 mm pitch. The strip wasformed by evaporating gold on a polyester film with
0.8 mm width and 0.2 mm inter-strip gap. To makenarrow strips on a wide area, we improved the supportof the evaporation mask and the evaporation of gold
was performed in a large vacuum chamber to avoid
the thermal variation of the mask. The method to put
resister array on the electrode for the charge division
read-out was also changed to make maintenance easy.
Instead of the direct gluing of resisters, the board ofresister array was newly constructed and was attachedto the electrode with an electric contact. Chip registersof 150 S1 were used as the resister array for the PPAC
with an active area of 150 x 100 mm 2 and 200 S1 wasused for the others.
In Fig. 2 shown is the position spectrum with a new

100 x 100 mm 2 PPAC irradiated uniformly by Q raysfrom 241 Am. As seen, the position spectrum is almost
flat and the peaks corresponding to the strips disappear. The differential linearity of the position is lessthan 2% for all types of the PPAC. The value of 2%
corresponds to the error of the resister used. The integral linearity of the position is shown in Fig. 3 for thecase of a 100 x 100 mm 2 PPAC. The linearity obtained
is ±0.1 mm for the positions within ±45 mm. For a
PPAC with 150 x 100 mm 2 active area, the value is±0.3 mm for positions within ±70 mm. The position
resolution was measured by placing an aluminum slit
0.5
0.4

0.3
0.2

E 0.1
5

g

J

(0.0)

1

.:5 (0.1) \.•I..LI

J~ r'\ 1M,

--u

"'l1

~

~

f.....

(0.2)
(0.3)
(0.4)

(0.5)
·50

-40

·30

·20

·10

0

10

20

30

40

50

X (mm)

Fig. 3. Integral linearity of the PPAC with an active areaof 100 x 100 mm 2 and 1 mm strips.

187with a 0.3 mm gap between the PPAC and the 24 1 Am
source and was 0.3, 0.6 , and 0.9 mm in FWHM for
PPACs with active areas of 50 x 50 mm 2 , 100 x 100
mm2 and 150 x 100 mm 2 , respectively. These values
correspond to the position resolution of 0.6% for all
PPACs.
The PPAC with an 150 x 100 mm 2 active area is
now used as a f6cal plane detector of RIPS at Fl.
The PPACs with 100 x 100 mm 2 are used at F2 and

188

F3. The PPAC with 150 x 100 mm 2 is also used for the
beam tracking for the radiation damage measurementsof semiconductors at E3 experimental room.
References
1) T. Kubo, M . Ishihara, N. Inabe, H. Kumagai , I.
Tanihata, K. Yoshida, T . Nakamura, H . Okuno, S.
Shimoura, and K. Asahi: Nucl. Instrum. M ethods Phys.
Res. , B70 , 309 (1992).

RIKEN Accel. Prog. Rep. 29 (1996)

I-Ieavy Ion Beam Test of Cosmic Ray Telescope for the First
Brazilian Scientific Satellite
T. Kohno, H. Kato, 1. Yamagiwa, and K. Nagata
We are promoting a joint collaboration program 1)of solar and anomalous cosmic ray observation with
United States group and Brazilian group aboard thefirst Brazilian scientific microsatellite. Assembling andintegrating the telescope box with seven solid state detectors and charge sensitive pre-amplifiers are in chargeof our Japanese group. We are now going to make anengineering model (EM) which will be tested by heavy
ion beam exposure in addition to various environment
tests such as vibration test, thermal vacuum test, andelectromagnetic compatibility test. After clearing allthese tests and confirming that there is no problem inthe design of the overall system, we proceed to the integration of flight model (FM) using space specification
parts and material.
The EM of the telescope box is now nearly completed. The main amplifiers, ADC board and the digital board which are in charge of US and Braziliangroups are not yet completed. Therefore we performed
the first heavy ion beam experiment of our telescope
system. The telescope structure is shown in Fig. 1.

Furthermore the isotopic tracks in each element canalso be seen. Using tlE - E method we made a histogram of atomic number distribution for this scatterplots, which is shown in Fig. 3. The mass resolutionof (Jm = 0.6 in FWHM was obtained.

800
~ 600

~
(")

t:::l 400

+
o

C\2

200

o

~-L~~-L~~-L~~-L~~-L~~~

a

200

400

600

800

1000

D2+D3+D4(MeV)

Fig. 2. Scatter plots of D2 + D3 vs D2 + D3 + D4 for thecase of Al thickness of 9.5 mm. The condition for thisplots is only events stopped at D4.

I

Ne j
I
I

Al

"

01

02 - 06

07....s::rn 40
;::l

o
CJ

Fig. 1. Cross sectional view of the telescope and the beamarrangement.

The main amplifiers used in this experiment were
our standard modules which we made using custom
hybrid ICs. The design of this custum IC of pulse
shaping main amplifier is basically identical to the hybrid IC which will be used in the flight model. The
used beam was Ne-20 of 135 MeV/nucleon.
In order to examine the telescope response for a wide
energy range, we took data for various Al thicknesses ofan energy degrader which is shown in Fig.I. We could
confirm that each detector res ponce to various energies
of Ne beam is consistent with the expected value obtained by calculation. Here we show in Fig. 2 an example of scatter plots of D2 + D3 vs D2 + D3 + D4. The
spread of the total energy seen in the abscisa comesfrom the energy loss straggling in the Al degrader witha thickness of 9.5 mm placed in front of D1. In addition to the main group of Ne, we can see the tracks offragments from F to Be produced in the Al degrader.

20

o 1AWIII1.LUI....,..IIII.I..IiI.J..J..-I~_IUoU-...
2

4

6

8

10

atomic number

Fig. 3. The atomic number histogram for events shown in
Fig. 2.

At the real observation in space, cosmic rays enter
the telescope from various directions within the opening angle of 22°, degrading the resolution due to thepathlength dispersion in the tlE detector. Therefore
we cannot observe isotopic distribution. (Our purpose
is elemental observation.) But by this experiment, we
could confirm the mass resolution of the telescope forthe parallel beam in addtion to the general response ofeach detector.
References
1) T. Kohno et al.: RIKEN Accel. Prog. Rep., 28, 132(1995).

189

RIKEN Accel. Prog. Rep. 29 (1996)

Progress in Beam Optics for RIKEN-RAL Muon Facility
K. Ishida, T. Matsuzaki , 1. Watanabe, and K. Nagamine
There has been major improvement in the muon
beam size since the beam was first produced at the
RIKEN-RAL Muon Facility in Rutherford Appleton
Laboratory on Nov. 9th of 1994,1) although the muon
beam intensity itself has not much changed. Also somebasic characteristics of the beam line were measured.
1. Measurement of basic characteristics of the beamline by using surface muonsSurface muons are produced when the pions stopand decay into two-body in the production target. The
momentum spectrum of the muons emitted from thetarget surface has a sharp high momentum cutoff at
29.8 MeV Ic and a slope to the lower momentum side
due to the various thicknesses that the muons have topenetrate to come out. In order to test the various
characteristics of the beam line such as finite momentum acceptance, we measured how the muons with thisspectrum are transported to the end of the beam line.
The muon beam intensity was measured as in Fig. 1
for various momentum settings. The horizontal axis
is the center momentum of the beam line calculated
from the magnetic field measurement. The positionof the high momentum cutoff after correction of theenergy loss in foils in the beam line was used for determining the real momentum-versus-setting relation,
which was found to be in good agreement with that
expected. The sharpness of the high momentum cutoff reflects the finite momentum bite of the beam line.
The four lines in Fig. 1 are the result of calculation
assuming Gaussian with standard deviations of 0, 1,
2, and 4 %. The measurement coincides with the lineof 2% in agreement with the optics design calculation. The measured slope at a low momentum side was

0
10

;::i

~

sharper than the calculation probably due to the increased multiple scattering in the beam line foils. The
measurement also indicates some muons existing above
the cutoff momentum, although at much lower intensity, which is considered to come from the low energy
pions decaying in flight around the production target.
2. Improvement of the beam size
As the J..tSR method is applied to new materials suchas high T c superconductors, it has become increasingly
common that these valuable samples are available only
in a small quantity. Typical sample area is less than
20 mm by 20 mm and considerably smaller than the
typical beam size. This could cause a serious problem.
In a typical J..tSR setup like in Fig. 2, the muons are focused to the sample and the positrons from muon decay
are detected. 2 ) However, the muons which did not hit
the sample may stop in surrounding materials such as
cryostat windows, sample holder or detectors. The J..tedecays from them may dilute the real signal from thesample or add complication to the interpretation of the
J..tSR signal. In order to avoid this, a collimator system
made of lead is normally used to limit the beam size.
However, the muons stopping in the collimator itself
may become a source of background when the space
restriction does not allow the collimator to be thickenough to stop the positrons produced. So there has
been a great demand to make the beam size as small
as possible.

measured

0%

8

C/l

C
0
;:::l

6

:::E

'0

'"'

4

Q)

.D

Fig. 2. Typical J.LSR setup showing a basic collimatorsystem with exchangeable end collimator, J.Le detectors
and sample in the cryostat.

E

;:::l

Z

2

20

22

24

26

28

30

Beam Line Momentum [MeV/c]
Fig. 1. The measured muon beam intensity versus beamline momentum. The four lines are the calculation with
momentum bite of 0, 1, 2, and 4% (standard deviation).

190

Figure 3(a) shows the typical beam envelope for thepart of the beam line from the solenoid exit to Port
2 where the J..tSR setup is located . The beam line
had been designed to obtain the maximal muon beam
intensity. In that case the beam size was typically

""CD

r---.

~
...J

«

~

_V

v
,

/

::::::~!:1 12fffi 16

\

> 20

'-V
/ 1"-

,;\

Xmax=

7

Ymax=

1,30cm!

'2,25cm/"rate was measured for three typical sample conditions,
namely "sample out", "small sample (20 mm x 20mm)" and "large material (50 mm x 50 mm)". The
subtraction of the first two gives the rate from the real
sample and the subtraction of the last two gives therate from the surrounding materials typically associated with a cryostat. We also tested placing a small
end collimator to limit the beam size. The signal tonoise ratio (SIN) was improved for the case with new
size-oriented tuning and a smaller collimator size.

24

70

§

'"0f-

0

6

~
Sl Ct d ~E;

'"u

~
~

W

""

;Z

~~

t:\

N

'"
~
~~~~

60

0

N
N""

""CD

~

...

c;.c;.c;.

SO

5:'

Ul

';;;

ar 40

~
Ul

.--/

~
~

/

..........

~ 12

!;;

f-

16
20
24

~

~ ~/

1\

f--~

/

V r--

~
\

"

..

c:

30

::l

0

Xmax =
0.4 7cm

Ymax=
1,1 0cm

u

20
10
0

\

\

I

Fig. 3. (a) Calculated beam envelope for the original
intensity-oriented beam line setting, and (b) that for
the revised size-oriented settings.

around 40 mm x 40 mm. The design was changed recently aiming at obtaining a smaller beam size. Figure 3(b) shows the result of new calculation, where
the beam size was minimized rather than maximizing
the total beam intensity. Because of the principle ofphase space conservation , we have to increase the beam
di vergence as we try to make the beam size smaller.
This means that the beam becomes wider in the lastquadrupole and more muons are lost there. However,these lost muons had been contributing mainly to thebackground and thus we do not lose too many signals.
This idea was tested recently. Figure 4 shows thenumber of J-le decay for the original intensity-oriented
setting and the new size-oriented setting. The J-le

(5

u
b -c

'iii
c:

2 v

~ c:
8
CIl

-c

(5

0

u
b -c

'iii
c:

~CIl

~ (§

2c: 0

0

N

CIl

v

-c
2c:

CIl

8 u(5

(§

Vi

Vi

:!:

:!:

Fig. 4. Source of J1e decay signals for two beam line
settings and two sizes of end collimator hole. The fraction coming from a 20 x 20 sample was improved forsize-oriented settings with the use of 20 mm end collimation.

This method may be applied also to the decay muon
beam depending on whether the intensity or the SIN
is important.
The authors thank Drs. G. H. Eaton, R. Kadono,
and F. Pratt for the discussions on the improvementof the beam line.
References
1) K. Nagamine: Hyperfine Interact., 87, 1091 (1994).
2) R. Kadono et al.: This report, p. 196.

191

RIKEN Accel. Prog. Rep. 29 (1996)

New Data Acquisition System for RIKEN-RAL JLCF Experiment
S. N. Nakamura and M. Iwasaki*
With the most powerful pulsed muon beam, a J.LCF
experiment is going to be carried out at RIKEN-RAL
Muon Facility. In order to acquire a large number ofdata measured in this experiment, a new data acquisition system (EXP95) was designed. Following characteristics are required for the new system:• A large number of data (1000 words/pulse = 50000
words/sec at maximum) can be acquired without serious dead time.
• Quality of obtained data can be checked during dataacquisition.
• Off-line analysis can be performed by the the same
software which is used for the on-line analysis.
• User-friendly graphical user interface is desirable.
To achieve above requirements, EXP95 was designed.
In the following section, the hardware and software
configuration will be described.
(1) Hardware Configuration (see Fig. 1)
EXP95 system consists of two computers. One is a
CAMAC Auxiliary Crate Controller (ACC: Kinetics

K3976) which concentrates on data taking. This computer has an MC68030 40MHz CPU with 1MB memory (upgradable to 4MB) and is able to access directly
to the CAMAC modules which convert a detector signal to digital information. Typically, one word dataacquisition takes 1.6 J.Lsec. When the memory of ACC
becomes full, acquired data will be transferred to ahost computer via CAMAC-SCSI interface (Kinetics
K3929) by Direct Memory Access (D MA). Heavy tasks
such as data analysis and data storage will be carriedout by the host computer. Current EXP95 system uses
DEC alpha station as a host computer. The K3929
CAMAC-SCSI interface is also used at RIKEN Ring
Cyclotron. 1) The SCSI interface data transfer rate is
not very fast (376 kword/sec in our case); however,DMA does not take place very frequently (typicallyless than once in every 30 sec) and it is not a serious
problem. The advantage of SCSI interface is that it is
widely used for workstations (WS) and personal computers (PC) and almost all WS/PC are equipped with
it. Recently, the performance of computers increased
very rapidly and the analysis software becomes heavier. When host computer becomes out of date, it canbe easily replaced by a faster (less expensive) computerwith SCSI interface.
(2) Software Configuration (see Fig. 2)

CAMAC Command

DDS or 8mm VCR Tape Drive~CC.M9 ~ CAMAC Modules
DATA- - - - __:o~~a~d~UD:~A_______~ Device ~Commands

Postscript Printert!~~____ _Host Computer

DATA

Internet

Fig. 1. Hardware configuration:
In the J.LCF experiment at RIKEN-RAL Muon Facility,
signals from detectors are converted to digital information by CAMAC modules. ACC K3976 reads module
data and stores the data on its memory. These data
will be transferred to the host computer (alpha station) via SCSI bus and stored on DDS/8 mm VCR
tapes. On-line analysis results can be printed out by
a postscript printer via network. On-line analysis results can be monitored from other workstations andX-terminals.
Meson Science Lab., School of Science, University of Tokyo

192

USER

Fig. 2. Software configuration:
EXP95 software can be roughly categorized in three.
The first one is MC68030 machine routine on ACC
which handles CAMAC commands and DMA request.
The second one is EXP95 main routine which consistsof six processes. They communicate with each otherto accept user commands, receive data from ACC andstore the data on a hard disk. The last software is
PAW++ developed at CERN. Some parts of the stored
data are handed over to PAW++ for on-line analysis.

On ACC K3976, the program which manages CAMAC commands is running. This program is written by MC68030 assembly language. A user can easily write CAMAC commands sequence using Macrolibrary without any knowledge on MC68030 CPU.
MC68030 cross-assembler is prepared on the host computer and the machine code will be loaded to K3976
by just selecting one button on EXP95 main window.
On the host computer, several processes are runningon Open-VMS to receive data from ACC, store dataon a hard disk, accept commands from user and soon. SCSI device driver was written using Queue I/O
system with a help of Dr. E. Widmann (CERN). On-

line and off-line analyses were performed by PAW++
software developed at CERN. 2) EXP95 handed oversome parts of acquired data to PAW++ and the data
quality can be checked during experiment. Acquired
data will be stored on a hard disk and DDS (Digital
Data Storage) device for off-line analysis. Stored data
can be analyzed after the experiment with the same
software used for the on-line analysis. PAW is working
on many platforms (even on PC), thus alpha station is
not necessary for the off-line analysis.
The user-friendly graphical user interface was constructed on X-Window system (Fig. 3).
The XWindow system can open windows on the other work-

89~ 9

/rtdi

Conswnl

1400

/

58

3423.
1150.
0075

1500

Fig. 3. EXP95 User Interface:
Main window locates right-down; run information and command panels are displayed. Obtained data
are analyzed by PAW++ . Histogramming and data fitting can be easily done with PAW++.

station or X-terminal via network. Thus, it is possible
to monitor the data taken in UK from the Wako campus though the response speed will be much affectedby band width of the network.
As a host computer, a DEC alpha station with
Open-VMS is now required. In the future, there isa plan to export EXP95 to a less expensive PC. Thisdata acquisition system was designed for the I1CF experiment at RIKEN-RAL Muon Facility; however, it

can be also used for I1SR experiments and nuclear experiments performed at RIKEN Ring Cyclotron and
KEK-PS.
References
1) N. Aoi, Y. Doki, Y. Watanabe, T. Ichihara, and A.
Yoshida: RIKEN Accel. Rep., 26 , 113 (1992).
2) CERN Application Software Group: CERN Program
Library, Q121 (1995).

193

RIKEN Accel. Prog. Rep. 29 (1996)

Installation of Tritium Gas Handling System for Muon Catalyzed
Fusion Experiment at RIKEN-RAL Muon Facility
T. Matsuzaki, K. Ishida, 1. Watanabe, K. Nagamine, M. Kato, K. Kurosawa,
M. Hashimoto, and M. Tanase
A tritium gas handling system (TGHS) has been
constructed for the muon catalyzed fusion (p,CF) experiment at RIKEN Muon Facility of Rutherford Appleton Laboratory (RAL) in U.K. A high purity D2/T2
target gas is required in the experiment for a precise
measurement of sticking probability in p,CF cycle. The
purification system employing a palladium filter in the
TGHS can produce a high purity D2/T2 gas without
3He impurity-component which is a decay product oftritium and captures a negative muon to terminate thep,CF cycle. The mixing ratio of D2/T2 target gas canbe adjusted in the system at the experiment site. The
detailed design of the TGHS was described in a previous report. 1 )The construction has been completed-after various
tests and inspections to conform to a tritium gas handling system. In the factory test , the performance of
purification device was investigated. The D2 gas with
3He impurity of 1% was purified by passing throughthe palladium filter and was analyzed by a gas chromatograph in the system. In Fig. 1, the component
spectra are shown; (a) before and (b) after the purification process. It was proved that the 3He impurity

component could be removed completely after the purification process.
The globe box containing the TGHS, secondaryenclosure clean-up system (SECS) and experimental target were transported to RAL and reconstructed in
port-1 experiment area of RIKEN Muon Facility. The
whole system was placed on a mobile stand adjacent
to a superconducting magnet to confine not only themuon beam to the target but also the decay electrons
not to hit the detectors. 2) In Fig. 2, the glove box with
the TGHS and SECS at Port-1 are shown. The superconducting magnet and muon beam line are seen
behind the TGHS system.

1000

Fig. 2. Photograph of the TGHS for J.lCF experiment at
Port-1 experiment area of RIKEN Muon Facility.

lo--~!--!~J~~~li~UU~I~IO----~15----~20----~25
Time (min)

10000

== b)

~
,.......

I

1000

"

'\

./

\

I

\

j

\

lUIJU .1\

IoJ

Vll J If -lIlA II/

15

10

20

25

Time (min.)Fig. 1. Component spectra of the gas chromatograph are
shown; ( a) before and (b) after the purification process.

194

The various tests were conducted to confirm the int egrity of the TGHS; helium leak, pneumatic and pressure tests for the tritium gas line and the pneumatic
test for the glove box. Under the working magnetic
field, normal operations of automatic valves, pressuregauges, thermometers, moisture gauge and oxygen meter were confirmed to investigate a possible magnetic
field effect to the whole system operation. The electrometers for in-line tritium monitors were relocated toevade the leakage flux by extending triplex cables fromthe ion chamber which transmit a very weak current.
The operation tests for major components in the
TGHS were conducted to approve their performance.
The inner gas of the glove box (3.4 m 3) was replacedby argon gas. In order to confirm the performance of
the SECS, the moisture and oxygen concentrations of
the glove box gas, instead of the hydrogen component,
were measured by circulating it through a ZrFe getterof the SECS, where the flow rate was 2 liter/sec . After
two hours operation, the moisture and oxygen concentrations were reduced from 600 ppm and 17 ppm down

to 220 ppm and 1 ppm, respectively.
A tertiary house with a ventilation system, as thethird enclosure, was built around the TGHS and superconducting magnet at Port-I. Two environmental
tritium gas monitors are located in the house. A stackgas monitor and a bubbler system to measure a tritium
water component are placed in the ventilation line.
The power control panel of the TG HS and electrometers for the in-line tritium monitors were placed ina separate room of the house. The electric power for
the TGHS , SEeS, tritium gas monitors and ventilation
system is supplied from an unperturbed power supply
which can last the power for 20 minutes to complete
the shut down procedure of the whole system at a possible power failure.

Two independent safety inter lock systems were constructed for a redundancy. For a safety approval to
the whole system, a large number of discussions anddocument-preparation were done.
The performance test of the whole system will be
conducted by using D2 gas and then a low level activity
test of tritium will be scheduled before the full activity
operation.
References
1) T. Matsuzaki et al.: RIKEN Accel. Prog. Rep., 28,134(1995).
2) K . Nagamine et al.: Muon Catalyzed Fusion, 1, 121(1987).

195

RIKEN Accel. Prog. Rep. 29 (1996)

Development of a New J.1,SR Spectrometer ARGUS
R. Kadono, I. Watanabe, K. Ishida, T. Matsuzaki, and K. Nagamine
In the time-differential p,SR experiment with apulsed muon beam, the pile-up of decay positron events
due to the limited time resolution of the detection system leads to the distortion of time spectrum. This
problem of distortion is already quite appreciable in
the time spectra obtained by the spectrometers withmultistop TDC's currently used at the existing pulsed
muon facilities and gives rise to a bottleneck of dataacquisition rate: The incoming muon rate is reduced
by beam collimation so that the distortion may remain within an acceptable level. This constraint on
the acceptable positron rate leads to the limitation ofpractical muon rate which is far below the highest intensity currently available from the muon sources at
the Rutherford Appleton Laboratory (RAL).
One alternative to cope with this challenging muon(and positron) rate is to move on to the so-called
analog technique 1 ) in place of the established digital
method,2) where the analog output from the positrondetectors is recorded/analysed assuming that the signal amplitude is proportional to the instantaneous
number of positron events within a time bin. This
technique, however, has uncertainty in the estimationof statistical errors. Another conservative choice is toincrease both time resolution and detector segmentation in the conventional digital technique to cover thepredicted event rates with acceptable level of pile-up
distortion. The current RIKEN system is aimed at thelatter solution, which is an important part of the newmuon facility completed recently at the Rutherford Appleton Laboratory under RIKEN-RAL collaboration. 3 )The new p,SR spectrometer ARGUS (Advanced
Riken General-purpose p,SR Spectrometer) is designed
to collect good p,-e decay events from 192 positron detectors covering more than 20% of the entire solid angle(see the schematic view in Fig. 1). This makes it nolonger practical to select good events by the coincidence technique (i.e., to accept events occurred simultaneously in a pair of positron detectors aligned along
the positron path). One of the major steps taken forthe design of positron counter is to get a direction sensitivity without resorting to the coincidence technique.
This has been accomplished by discrimination of lightintensity in a planer scintillator which is dependent
on positron trajectories. The drawing of scintillatorswith rigid light guides and photomultipliers is shown in
Fig. 2a. The longer axes of the scintillators are alignedin the radial directions so that the positrons from thesample position penetrate through their longest path.
The yield of scintillation light is proportional to thepath length in the scintillator when the positron energy
is near the minimal ionization regime (e.g., 10 0 "-'1 MeV
in lucite) and thereby the highest light yield (and ac196

Scinti. Counters
6x16 F&B each(n tota r,,41tx25% )Photomultipliers(HF tolerable)

10cm

LF iHelmholtz Coils!

TF Coils

Fig. 1. A cross-sectional view of the ARGUS spectrometer.
The muon beam axis is in the left-right direction.
cordingly the highest signal from the photomultiplier)is expected for the positrons emitted from the sample.
Because of the short distance between the sample position and scintillators the bending of trajectory due tothe magnetic field from a spectrometer magnet is negligible for high energy positrons. The discriminationlevel for the photomultiplier signal was determined sothat the coincidence rate of the neighboring counters
might be less than 10% of the single rates. An example of tuning result is shown in Fig. 2b where boththe single and coincidence event rates are plotted as afunction of discrimination level. Thus, it demonstrates
that a reasonable direction sensitivity is established forthe single counters by exploiting the character of minimal ionization. (However, we note that this method
may not work efficiently for the discrimination of low
energy positrons which tend to yield much higher signals to the single counter.)
Another major advent in the new detection systemis the large scale application of high-field-tolerant photomultipliers (R5505, Hamamatsu Co.) , with which we
can remove the shielding of phototubes against fringe
fields from experimental magnets. Although their gain
is slightly low (1"'-'10 6 ) compared with those for standard high energy physics experiments (I"'-' 10 7 ) the vari-

lOcm

I

i
i

i .. .
i:Ih~~~<"" " " " "rl~~r~)~~~······· · · · · ·Il;~" ~J ._. _\-_\--,-._. ~~~~~t~rs ._. _
j

a)

A B

150'~~~~~'~~T'~~~~~~~~~b)....-..

1 100

'-'
tI)

E-<

?3

0

U

50

0

1.5

2.1

Fig. 2. a) Design of positron detectors for ARGUS spectrometer. One unit consists of six planer scintillatorsplaced along the radial direction seen from the sample
position. b) Single and coincidence rate for a neighboring pair of positron detectors as a function of photomultiplier cathode voltage, where the higher cathodevoltage corresponds to the lower signal discriminationlevel.
ation of gain is less than 10% below 0.3 T (when thefield is coaxial with the tube). This allows considerable
flexibility for the compact design of the spectrometer.
As shown in Figs. 1 and 2b the phototubes (1 inch dia. ,90 mm long) are closely assembled near the magnet
coils along with the fringe field direction and opticallyconnected to the scintillators by rigid light guides madeof lucite.
The number of detector requires high-density
TDC's, for which those developed either in UTMSL(single channeljCAMAC slot 2 ») or in RAL (two channelsjCAMAC slot) would not suffice: It should be

noted that any two of those 192 signals should not be
OR'ed before recorded by TDC's, otherwise it would
lead to the increase of pile-up probability in a TDC.
In order to realize such a high-density system we haveadopted a TDC (model 2277, LeCroy Co.) which has
32 input channels in a single slot device with multistop
capability of up to 16 events within 64 J-LS. The double
pulse resolution of the model 2277 is 20 ns which isacceptable for the predicted event rate. Thus, using
6 TDC modules to cover 192 detectors, the system
can tolerate 10 3 positron events per muon pulse (i.e.,
x 104 "-'5 positron events per second at a rate of 50 Hz
in RAL-ISIS facility). The estimated distortion due
to the pile-up is less than 5 x 10- 3 in routine J-LSR
experiments taking 3 x 10 7 events per hour.
The spectrometer magnets are designed for the conventional {tSR experiments with zero field (ZF) , transverse field (TF), and longitudinal field (LF). The LF
coils (water cooled) satisfy the Helmholtz condition
with 110 mm gap to generate a maximal field of 0.4 Twith relative homogeneity of 10- 4 within 20 mm coreradius at the sample position (i.e., the center between
the coils). A pair of small correction coils are placed in
the LF direction and used together with other coils to
obtain zero field condition at the sample position. The
vertical pair of coils are used also to generate a transverse field up to 4 mT. The fringe field from Helmholtz
coils with maximal excitation is about 0.25 T at theposition of photomultipliers and thereby the change ofthe gain is less than 10%. The positron detectors areassembled around the bored coils, leaving an apertureof 10 cm diameter along the beam direction. All thepower supplies for these coils are controlled by a dataacquisition program coherently with histogramming of
J-LSR data, which is useful for some particular measurements where the automatic progression of magnetic
field is desirable (e.g. , resonance experiments, etc.).
References
1) Y. Kawashima, Y. Watanabe, and T. Yamazaki: Hyperfine Interact. , 32, 873 (1986); K.-H. Miinch, A. Krazter,
G. M. Kalvius, K. Maier, J . Major, M. Hampele, andT. Pfiz: ibid. , 87, 1049 (1994).

2) F. Shimokoshi, Y. Kuno, K. Nagamine, and T.
Yamazaki: Nucl. Instrum. Methods Phys. Res. , A297,
103 (1990) .

3) K. Nagamine, T. Matsuzaki, K. Ishida, I. Watanabe, R
Kadono, G. H. Eaton, G. Thomas, H. J. Jones , and W.
G. Williams: Hyperfine Interact., 87, 1091 (1994).

197

RIKEN Accel. Prog. Rep. 29 (1996)

Development of a Resonance Ionization Buffer Gas Cell for Laser
Spectroscopy of Refractory Elements and Actinides
M. Hies, T. Ariga, T. T. Inamura, W. G. Jin, T. Murayama, and M. Wakasugi
On-line laser spectroscopy experiments of refractoryelements and actinides are planed at the RIKEN accelerator facility using a combination of resonance ionization spectroscopy (RIS) and ion guide technique(IGISOL).I) To optimize the laser excitation of suchan on-line experiment, the excitation cross section andthe spectral line profile in the buffer gas have to beinvestigated with stable isotopes in the case of refractory elements and with long-living isotopes in the caseof actinides in a reference buffer gas cell.
The main part of the reference chamber is a 6-way
UHV-CF63 stainless steel double cross filled with a noble gas like argon (purity 99.9999%) at a typical gas
pressure of 30 mbar (see Fig. 1). The atoms are evaporated from a thin filament (25- 50 /-Lm thick) throughthermal heating with a current of 10 to 20 A into thegas and are stored in the gas for the typical diffusion
time of 50 ms. The stored atoms are then ionized withan overlapped pulsed laser beam (diameter 10 mm).
The produced photoions are transported with the helpof an electric field to a pick-up electrode (-200 V).
The ion current is measured with a charge sensitive
detector as a function of the detuning laser frequency.

and autoionization states have been discovered. Fromthe pattern of the Rydberg states the ionization energy of Hafnium could be determined to (55070 ± 50)
cm- 1 . This value agrees with the calculated value 2)of (54700 ± 600) cm-I, but disagrees with the previous value of (53200 ± 800) cm- 1 measured via electron
impact method. 3)- 55125 em"~I.L'

1200.,-356.330nm

HI ground statetransition at; ' 1000

ci

~
Q)

800

368.224 nm

600

6.9 GHz27150 em"

E.S.
A,seano em,1

G.S.

Ol

CO

..c
(,,)

if> 400

a: 200368.22368.20368.24368.26/...1 [nm]b) 5000
Autoionizing states

Rydberg states"":' 4000
:J

ci

~
Q)

3000

OJ

~ 2000if>

Charge Sensitive Detector(,,)

a: 1000
o H~+-~:.l4'oIof:!!I
352

354

356

358

360

362

364

366

368

370

/...2 [nm]to turbo pump P--.----'and gas in let~
ioacti~e" ,Filament\.

25",m Re/To;W fo;1"

with "2mm Th spot

\~;Zl

6

Current"
Hea ting@:

Ij---.: ;'"<:.---------'.....
.....
25mm)'...

Fig. 1. Experimental setup of the buffer gas cell.

As a first candidate the refractory element hafnium(M.P.2227 DC) has been chosen. The filament was a
25 /-Lm thick Hf-foil (5 x 20 mm 2). An excimer-dyelaser combination supplying laser pulse energies in therange of mJ / cm 2 was used to investigate the laser
excitation. Typical two-photon two-color ionization
with excitation in the ultra-violet spectral range areshown in Figs. 2(a) and (b). A lot of Rydberg states

198

Fig. 2. (a) Laser detuning of the first excitation step overthe hafnium ground state transition at 368.224 nm and(b) Laser detuning of the second step over the ionization
limit. The excitation scheme is shown in the inlet of
Fig. (a),Further experiments on actinides are planed. Therefore special filaments have to be used, where long-living
isotopes like 232Th (total amount 10 14 atoms, 3*10 - 4Bq) are electrodeposited with a spot diameter of 2- 3
mm on a thin rhenium foil (25 /-Lm thick) as describedin Ref. 4.
References
1) M. Hies et al.: This report , p. 177.
2) W. F. Meggers: NBS Monograph, 153, 3 (1976).
3) E. G. Rauh et al.: J. Chern. Phys., 60 , 1396 (1974).
4) H. Wendeler et al.: Nucl. Instrum. Methods Phys. Res.,
A334 , 93 (1993).

RIKEN Accel. Prog. Rep. 29 (1996)

A New Beam Line for Material Irradiations in the Ring Cyclotron
T. Kambara, M. Kase, M. Matsuda, T. Mitamura, and Y. Awaya
We report about a new setup for material irradiation
installed at the Ring Cyclotron.
The radiation effects on materials like hightemperature superconductors have been studied withhigh-energy heavy ions (1010 to 10 12 ions/cm 2 ) fromthe Ring Cyclotron. I) Formerly a one-meter-diameter
vacuum chamber on the E2b beam line has been used
for the irradiation. Recently, along with the increaseof demands for heavy-ion irradiation on materials, it
has become necessary to handle more samples within
limited beam time without spending too much timefor exchange of samples. It is also necessary to have auniform distri bu tion of the dose and measure the total
dose precisely. Therefore a dedicated beam line with asetup for material irradiation was desired.
The setup is constructed at E5a beam line, which has
been used for biological irradiation as well as E5b. This
beam line is already equipped with a wobbler magnet
system which enables one to get a uniform beam distribution. As shown in Fig. 1, the new setup consists of
two parts, one for beam collimators and monitor systems and another for sample handling and irradiation.

Beam current feedthroughr--- --- ---1
1000

linear Feedthrough(SOOmm stroke)

Sample Exchange Chamber

Beam monitor box
Gate Valve (NW1 00)

ProfileFour-blade
Bellows

beam

linear I Rotary
Feedthrough(200mm stroke)

Fig. 1. Side view of the material irradiation set-up.

The beam from the accelerator which passes throughthe wobbler is shaped by a four-blade slit which can beremotely controlled. The spatial distribution and theintensity of the beam after the slits can be monitoredwith a beam profile monitor and a Faraday cup. Those
equipments are mounted on the beam monitor box.
The irradiation chamber is equipped with a sample handling system and the second Faraday cup withlarge aperture and depth. Up to four samples can bemounted on a sample holder supported by a 50cmstroke linear motion feed through. The position andthe angle of the samples are fixed by another linear-rotary motion feed through at the bottom of the chamber. The beam intensity at the sample has been normalized with the second Faraday cup.
When the samples are exchanged, the holder is
moved to the sample exchange chamber and then thegate valve is closed. The sample exchange takes about
20 minutes including evacuation. The first irradiation
with this setup was successfully performed in September 1995 with 26 MeV/nucleon Xe ions.
References
1) M. Terasawa et al.: Physica C, 235/240, 2805 (1994).

199

6. Material Analysis

RIKEN Accel. Prog. Rep. 29 (1996)

RBS Study of Tb-Implanted Sapphire (II)M. Kumagai and M. Iwaki
A study has been made of the luminescence during
Tb-implantation in A1 2 0 3. The substrates used werecolorless and transparent single-crystal Al 2 0 3 with the(0001) surface. The surfaces of all wafers were mechanically polished before ion implantation. The Tb+ ion
implantation was performed at an energy of 100 keVwith doses between 10 13 and 10 17 Tb+ /cm 2 at room
temperature. The beam current density was about
0.1 J1A/cm 2 . The luminescence owing to Tb 3+ fromTb-implanted Ab03 was seen during Tb-implantation.
The luminescence spectrum from Tb-implanted Ab03
was green.
In order to clarify the mechanism of ion beam induced luminescence of Tb-implanted Al 2 0 3, the composition , damage and Tb-Iattice sites in the Tbimplanted layers of Al 2 0 3 have been estimated by
Rutherford backscattering spectroscopy (RBS). RBS
spectra have been measured at room temperature byusing 1.5 MeV He+ ions with a scattering angle of 150 0 •Figure 1 shows random and (0001) aligned spectra
for the specimens implanted with a dose of 1 x 10 16
Tb+ /cm 2 . The Tb+ depth profile in the random spectra of implanted specimen is of a Gaussian-type, andthe Tb amount calculated from the spectra is in good
agreement with the nominal value of the implanted
dose. The standard deviation calculated from the
FWHM of the Tb spectra is about 15.4 nm , which
disagrees with the predicted value of about 6.2 nm by
the TRIM-gO code. The depth (Rp) corresponding to
the Tb peak in the spectra is about 20.3 nm, whichshows a smaller value than the projected range of Tb
of about 23.4 nm predicted from the TRIM-gO calculation. These results are almost the same as thatobtained forTb implantation into (1102) sapphire asshown in our precious report. 1)...,en 20000
c: Random:J0u"- 15000

lxl016 Tb+/cnt

,

..

'0
r-t

0.>

Rp=20.3 rrn

'M

>-

\Tb
~

10000

Q)

.....c
c..

AI

...,
...,
5000
0.>

m
0

en

~

0

co

(I)

0
0.0

0.5

1.0

1.5

Energy / MeV
Fig. 1. Random and (0001) aligned spectra obtained for
Tb-implanted Ab03 with a dose of 1 x 10 16 Tb+ /cm 2 .

The (0001) aligned spectrum of the implanted sapphire shows that the scattering yields of Al and 0 near
the surface increase. The enhancement of the yields
results from the radiation damage induced by Tbimplantation, but the spectrum shows that no amorphization takes place even at the high dose. The scattering yield from Tb in the (0001) aligned spectrum
is identical with that for the random spectrum. The
accordance of the two spectra reveals that most of theimplanted Tb atoms may sit at the random sites.
The relationship between the surface characterization and luminescence is under investigation.
References
1) M. Kumagai and M. Iwaki: RIKEN Aceel. Prog. Rep.,
28, 142 (1995).

201

RIKEN Accel. Prog. Rep. 29 (1996)

Sample Charging Effect on Satellite Spectra of Ion-Induced X Rays
K. Maeda and H. Hamanaka*
Abnormally strong characteristic X rays are emitted from some metal fluorides after their bombardment
by accelerated ions. I) The enhancement of the X-ray
yields has been ascribed to the charge build-up in insulating materials that is followed by discharge dueto the production of high-flux energetic electrons. Xray spectra induced by ions have strong satellite lines
arising from multiple ionized states. On the other
hand, the satellites in the electron-excited X-ray spectra are very weak compared to their parent diagram
lines arising from single-vacancy states. Therefore, ifenergetic electrons produced by discharge are the truecause of the abnormal enhancement, sample charging
must have effects not only on the yields of characteristic X rays but also on the fine structures of the X-ray
spectra. In the present work we examine the above hypothesis by measuring the silicon K 0: satellite spectraof Si0 2 (fused quartz) bombarded by He ions undervarious experimental conditions .2 ) Fused quartz wasused as a target sample because it is a good insulating
material and, moreover, the multiple-vacancy satellite
structures of Si K 0: have already been extensively investigated.
X-rays spectra were excited by 1.5 MeV He+ ionsand measured with a high-resolution PIXE spectrometer of Hosei University. The spectrometer was
equipped with an ADP (110) plane crystal and aposition-sensitive proportional counter. Crystalline silicon was used as a reference non-insulating sample. A
tungsten filament taken from an electric lamp was set
in front of the sample target to spray electrons for neutralizing the positive charge built-up in the target. Figure 1 shows Si K 0: spectra of Si0 2 bombarded by 1.5
MeV He+ ions under the following experimental conditions: (a) the vacuum in the scattering chamber [p] was
1 x 10- 2 Pa and the power of the W filament [w] wasOW; (b) p = 1 X 10- 2 Pa, w = 6 W; (c) P = 9 X 10- 2
Pa, w = a W; and (d) p = 9 X 10- 2 Pa, w = 23 W.
The diagram line (K LO) in Fig. l(a) is very strongin comparison with the K Ln satellites. Here, K Ln
denotes the initial state with single K and n L vacancies. The ratio of the integrated intensities of the
K L and K L 1 lines is 100 : 7, very similar to that ofelectron bombardment of 100 : 9. If this strong diagram line was induced by energetic electrons during
the discharge, the elimination of the sample charging
should weaken the diagram line and make the satellites
evident. As expected, the satellites appeared prominently, as seen in Figs. l(b) and l(d) , when electron
showers were introduced in the system. The intensity
distribution of the K LO : K L1 : K L2 : K L3 lines is°College of Engineering, Hosei University

202

KLO KL1 KL2 KL3

I

I

!

I

(a)
1x10-2 Pa, OW

80
,

40

O~~~'~~-=~====",~~~~~(b)
1x10-2 Pa, 6 W

]80
tii

E 40

<5

.s
.-

(c)
9x1o-2 Pa, OW

,

.' .
".'

. ,....

"\......

_-

...

,~

80

i ~

40

1720

&~10-2 Pa. 23 W

Nv\
1740

1760

1780

1800

X-ray energy (eV)Fig. 1. Si K a spectra of a fused quartz bombarded by 1.5
Me V He + ions under different experimental conditions.

100 : 167 : 67 : 8, when an electron shower of high-flux
is applied as shown in Fig. 1 (d) , This ratio is close tothat of the silicon of 100 : 172 : 73 : 12. The intensity distributions of the satellite spectra in Figs. 1(b)and l(c) are intermediate between those of Figs. l(a)and l(d). The electron flux in condition (b) is not
sufficient to fully neutralize the positive charge in thesample. Under condition (c), charge leakage by way ofresidual gas has likely occurred b ecause the vacuum in'the chamber was not high.
The change of the intensity distribution of the satellite spectra shown in Fig. 1 leads to the conclusion thatthe characteristic X rays induced by sample charging
is strong enough so that the multiple-vacancy satellites are obscured by the intense diagram line. Thus,by means of high-resolution measurements, we have
proved the hypothesis 1) that the enhancement of Xray yields from insulating targets is caused by energetic
electrons generated by charge build-up and subsequent
discharge. The above argument was confirmed by results of experiments for ion-induced Ca K 0: spectra of
CaF 2 and CaB 6 , in which the intensities of the K LO
and K L1 lines were measured as functions of the magnitude of the electron shower. 3 )References
1) J. Kawai, K. Maeda, N, Sakauchi, and I. Konishi: Spectrochim. Acta, B50 , L1 (1995) .
2) K. Maeda and H. Hamanaka: ibid., in press.
3) H. Hamanaka, K. Hasegawa, and K. Maeda: Nucl. Instrum. Methods Phys. Res., in press.

RIKEN Accel. Prog. Rep. 29 (1996)

Correlation between Seawater Temperature and Sr ICa Ratios in
Otoliths of Red Sea Bream Pagrus major
N. Arai, w. Sakamoto,* and K. Maeda
Fish otoliths, ear stones which function as a detector of acceleration and sound, are generally composedof aragonite crystals and continuously deposited fromfish birth to its death. In addition, trace metals canenter the crystals of calcium carbonate and the amountof the metals seems to vary according to the environmental parameters such as temperature that fish has
experienced. Especially strontium is well known asa good indicator of ambient temperature. An in-air
PIXE was adopted to detect a small amount of strontium in otoliths of red sea bream Pagrus major. In aprevious study,1) we indicated that the Sr concentration in the otoliths of red sea bream reared in different
three sea areas that showed different seawater temperatures depended on the temperatures ; Sr increased in
the higher temperature condition. The object of thistemperature controlled experiment is to examine thecorrelation between seawater temperature and Sr concentration and the other factors that affect the correlation.
The otolith samples were removed from juvenile red
sea bream reared in two experiments. Forty-five individuals of 64 days old juveniles were kept in fivetanks in the first experiment (Exp. 1) and 15 individuals of 119 days old were kept in the other experiment(Exp. 2). Seawater temperatures were controlled at 17,
20, 23 , 26, and 29 cC. Fish were fed with a commercial
assorted food three times a day.
Otoliths surfaces were not cut nor polished and bombarded in air by a 1.6 MeV proton beam generated in
the RIKEN Tandetron accelerator. The proton beam
was collimated with a carbon collimator with a I-mm
diameter hole and brought out from the vacuum system into air through a 6 J-lm thick Al foil, and traveled
10 mm to the target. Path lengths in air and the Al foil
caused reduction in the proton energy to 1.16 MeV andalso spread the beam spot about 1.2 mm in diameter.
X-rays emitted from the target were detected withan Si(Li) crystal made by EG&G Co. through a 74
J-lm Al absorber to attenuate CaK X-rays, since theotolith is almost composed of pure calcium carbonate.
The distance was 26 mm between the top of the Si(Li)crystal and the beam spot on the target. The detector
position was kept at 135 0 with respect to the incident
beam direction. PIXE spectra were measured by monitoring a beam current and accumulated for a total
beam charge of 20 J-lC. Experimental errors were examined using a NIST standard argillaceous limestone
SRM-IC.
Figure 1 shows the correlation between seawatertemperature and Sr/Ca concentration ratios. The ratios in otoliths in smaller juveniles increase in proportion to temperature, while the ratios in larger juveniles
are almost constant values. This result indicates thatthe ability of red sea bream juveniles to discriminate
Ca from Sr depends on its body size as well as ambient
seawater temperature.

4.5

!

!

"

('")

b
orx

I

I
6

15

3.5

15

15

ctS

t

()

"L:

Cf)

I

Exp.1
Exp.2 I

0

4.0

13

j

f

3.0

f

!

I

13~

6

6

6

S.E.

Mean

5

2.5
16

18

20

22

24

26

28

30

Temperature (OC)Fig. 1. Correlation between seawater temperature andSr/Ca ratios in juvenile red sea bream otoliths. Fork
length was ranging from 31 to 66 mm in the Exp. 1
and was ranging from 82 to 108 mm in the Exp. 2.
Numerals under and above error bars are the numberof specimens.

References
1) N. Arai, W. Sakamoto, and K. Maeda: Fisheries Science, 61, 43 (1995).

Faculty of Agriculture , Kyoto University

203

RIKEN Accel. Prog. Rep. 29 (1996)

Whether Ion Beam Attracts Ions in Solutions or Not?
J. Kawai and K. Maeda
In our previous report,1) the x-ray intensity inducedby accelerated charged particles was not proportional
to the concentration of Cu 2+ ion in aqueous solutionsof nitrates. That is to say, the Cu K a intensity gradually increased with the increase of the total accumulated charge when the projectile intensity was constant. This increasing factor was more than ten for
a 60 ppm Cu solution and the factor was decreased
with the increase of concentration; the factor was twofor a 600 ppm Cu solution and one for 6000 ppm. The
experiment was performed with a horizontal 6-MeV
He-ion beam. Thus the He beam interacted with theCu solution through a thin Kapton window which separated the solution from the air. We have concluded
that this nonlinear behaviour of x-ray intensity is dueto the deposition of the solute elements on the Kapton
surface.
We have constructed a vertical beam PIXE (Particle Induced X-ray Emission) beam line 2) at RILAC
to measure solutions without using a window. On
this beam line, we have tested whether He-ion
beam, which was introduced into free aqueous so-

204

lution surface, could attract or concentrate ions ornot. We measured 0.100 M KBr solution , 0.0020
M stearyltrimethylammonium bromide (STAB) solution, and 0.00021 M STAB solution. STAB isCH3(CH2h7N(CH3h +Br- , thus the Br- ions are attracted at the solution surface ,3) and the concentrationof Br- at the surface was expected to be higher thanthat at a deeper place of solution. However , the present
PIXE measurement indicates neither any nonlinear effect nor the high concentration of Br- at free aqueous
solution surface. This is because the PIXE analysis
is not surface sensitive to detect the top few layers ofsolution.
References
1) K. Maeda and J. Kawai: RIKEN Accel. Prog. Rep. , 27,
123 (1993).
2) J. Kawai and K. Maeda: Int. J. PIXE, 4 , 147 (1994).
3) H. Tanida, 1. Watanabe, and H. Watarai: Book of Abstracts, 8th Int. Conf. on X-Ray Absorption Fine Structure , Berlin, Aug.- Sept. ThFr-16 (1994).

IV. NUCLEAR DATARIKEN Accel. Prog. Rep. 29 (1996)

Status Report of the Nuclear Data Group
Y. Tendow, A. Yoshida, A. Hashizume,* and K. Kitao
The Nuclear Data Group has been continuing thedata activities mentioned below since the previous
year. I)This year, one of the staff (Y.T.) has retired reaching
the age limit. But he is supposed to continue the data
works as a non-regular member of the Institute for thecontinuity and completeness of nuclear data activitiesof the group.
(1) Nuclear reaction cross-section data (EXFOR)Compilation of charged particle nuclear reaction
cross sections has been continued. Cross sections to
produce 20 radioisotopes of medical use: 11 C, 13N,
150, 18F, 28Mg, 52Fe, 67Ga, 68Ge, 74As, 77Br, 82Br,
77Kr, 81 Rb , 82mRb, 111 In, 123Xe, 127Xe, 123 1, 1241, and
125 1 as well as old data which are not included in the
EXFOR master file up to now and new data appearedin recent journals are continued to be collected andcompiled into EXFOR files.
(2) Evaluated Nuclear Structure Data File (ENSDF)
We have been participating in the ENSDF compilation network coordinated by the Brookhaven National Nuclear Data Center (NNDC). The evaluationand compilation of A = 118 mass chain has been published this year. 2) The author post-review and galley
for A = 129 evaluation has been completed and sent
back to the NNDC for publishing. Mass chain A = 127
is now in the stage of review at the NNDC. A = 120
evaluation is now under progress.
(3) Nuclear Structure Reference file (NSR)
We are engaged in collecting and compiling secondary references (annual reports, conference proceedings, etc.) appeared in Japan since the previous year
into the Nuclear Structure Reference (NSR) file and insending it to NNDC.
The compilation of 1994 annual reports has been
completed and sent to the NNDC. Japanese Secondary
sources surveyed this year are as follows (in code namein NSR):
RIKEN (RIKEN Accel. Prog. Rep.) ,JAERI-TV (JAERI Tandem & V.D.G.),
JAERI-TIARA (JAERI Takasaki Ion Ace. Advanced Rad. Appl.) ,INS (INS Univ. Tokyo),
UTTAC (Univ. Tsukuba Tandem Accel. Center),
RCNP (Res . Center Nucl. Phys. Osaka Univ.) ,OULNS (Osaka Univ. Lab. Nucl. Study),
KUTL (Kyushu Univ. Tandem Ace. Lab.),CYRIC (Cyclo. Radioisot. Center, Tohoku Univ.).
(4) Others
The regular IAEA Technical Nuclear Reaction Data
Centers (NRDC) Meeting was held at the IAEA Nuclear Data Section (NDS) in Vienna on 2- 4 May 1995.
The proposal for restructuring of the going worldwide
cooperation network which had been proposed at thelast IAEA meeting was continued to be discussed inthis meeting, and a document of conclusion and agreement was reached and signed by all of the 11 center heads participating in the network. In the courseof discussion, radical aspects in the original proposal
for restructuring the network were rather toned down.
The document only provides the purposes and functions of nuclear data network activities as well as theunique responsibilities and special expertise of eachcenter. It was also recognized at the meeting that themost of leading data centers in the network were menaced with cutting down on the budget and decrease in
man power.
A new PC program package "NUCHART for Windows" has been released from IAEA NDS. It provides
an on-screen chart of nuclides which pops up various
nuclear data of the nuclide clicked by the mouse. Another program package "VuENSDF for Windows" alpha test version has been released from LBL which displays decay scheme drawings on the basis of ENSDF
inputs . An MS-DOS program "ENSDAT" , available
from BNL, also provides a postscript file of decay
scheme drawings like that in "Nuclear Data Sheets"from ENSDF inputs.
References
1) Y. Tendow, A. Yoshida, Y. Ohkubo, A. Hashizume, and
K . Kitao: RIKEN Aceel. Prog. Rep., 28 , 145 (1995).
2) K. Kitao: Nuclear Data Sheets, 75 , 99 (1995) .

Japan Atomic Energy Relations O rganization

205

RIKEN Accel. Prog. Rep. 29 (1996)

Measurements of Activation Cross Sections of Energy Up to110 MeV for Several Neutron-Induced Reactions
N. Nakanishi, S. Fujita, S. Nakajima, M. Watanabe,* and H. Ohishi*
Neutron activation cross sections for 12C, 27 AI, 56Fe,, 58Ni , 115In, and 197 Au detectors (foils) were measured in the neutron energy range up to 110 MeV by
the activation method. As well known, the method
gives the activity which is represented as the product of an activation cross section and a neutron flux.
Information on a neutron spectrum, therefore, is indispensable in order to obtain that of the activation crosssection. Activity A is given by the following expression,
59CO

A=

Table 1. Studied reactions and physical properties of the
gamma-ray transitions concerned.
Half-life ),-rayenergy (MeV)
TargetReaction
12C(n,2n)l1C
0.511
20.38 mC
27 AI(n,a)24Na
1.369
Al
15.02 h56Fe(n,p ) 56 Mn
0.847
2.579 hFe
0.811
Co 59Co(n,2n)58Co
70.79 d0.847
Co 59Co(n,a)56Mn
2.579 h58Ni(n,p )58 CO
0.811
70.79 dNi
58Ni(n,2n)57Ni
1.378
Ni
35.94 h115In(n,n')115mIn 4.486 h
0.336
In
0.329
Au 197 Au(n,4n)194 Au 3.955 h
0.356
Au 197 Au(n,2n)196 Au 6.183 d
0.412
Au 197 Au(n,),)198 Au 2.696 d

J¢(E) . cr(E) dE,

where ¢(E) and cr(E) are an energy spectrum of neutron flux and an activation cross section, respectively.
We adopt neutron spectra measured by Meier. 1) These
metal foils were irradiated by a neutron flux with a continuous energy spectrum which was produced by 113
MeV protons incident on thick C, and Fe targets. The
gamma-rays from the reaction products in the foil were
measured using a Ge-detector after irradiation.
The reactions which were studied are listed alongwith the half lives and energies of measured gamma-

(a)

10 2

D 10 ':2u 10°

(c)

(b)

10 3

Exp.
alice
present

EU;
crays in Table 1. Activation cross sections are unfoldedin the same algolithm as that of the Sand II. Calculated results by the ALICE code are used as initial
guesses in unfolding processes. Typical exsamples of
the neutron energy dependence of activation cross sections are shown in Fig. 1. In the 27 AI(n,a) 24 Na reaction, other reactions such as (n ,n 3He), (n,2d), (n,npd)

10'
Exp.
alice
10 3
present

10 2

r\
.-.J

10 2
10'
10'

IJ.)

(f)

X 10"

10°

10' 2L.........o-L~---'-~~~-'-~-'---"----'o 20 40 60 80 100 120

10"

10°

o

20

40

En (MeV)60

80

100 120

En(MeV)

,
10'

0

20

~

--0--

~~
I~

,

40

--0--

60

80

Exp.
alice
present

100 120

En(MeV)

Fig. 1. Activation cross sections of typical examples; (a) 12C(n,2n)l1C, (b) 27 AI(n,a) 24 Na and (c)59Co(n,2n)58Co.

and (n,2n2p) are also included. In the 59Co(n,2n)58Co
reaction, the cross section becomes very small in a higheL\ergy region.

Faculty of Science and Technology, Chuo University

206

References
1) M. M. Meier et al.: Nucl. Sci. Eng., 102, 310 (1989)
and private communication ('94).

V.

DEVELOPMENT OF ACCELERATOR FACILITIESRIKEN Accel. Prog. Rep. 29 (1996)

Status of RIKEN 10 GHz' ECRIS
T. Nakagawa, T. Kageyama, M. Kase, A. Goto, and Y. Yano
For the experiments to search new isotopes, intense neutron rich beams, such as 50Ti and 48Ca, arestrongly demanded. To produce such beams, it is effective to use enriched materials, because of the low natural abundance of the ions. As the enriched isotopes arenormally sold as oxides, the method to produce highly
charged ions from oxide materials described in Ref. 1 is
one of the best ways. However, it is not advantageous
to make a rod of oxide materials of the enriched isotopes from the point of view of cost performance. We
tried to put the oxide powder into Ah03 or Si0 2 tubes(2 mm in inside diameter, 4 mm in outside diameter)
and insert them directly into the plasma.
At first we compared the beam intensities of 48Ti byusing 1) a tube (Si0 2 or A1 2 0 3) filled with oxide powder of natural Ti and 2) an oxide rod. The conditionof the ECRIS was kept same for both cases. Figure 1
shows the obtained beam intensity of 48Ti ions for eachcharge state. The beam intensity produced by using
the tube method is almost the same as that of the rod
method.
Encouraged by this success, we have tried to produce
50Ti ions from 50TiO powder. As shown in Fig. 2, the100r----------.--------.-------~TiO(Al 20 3 tube

TiO rod

TiO(Si0 2 tube)

1best result was obtained with using an Al 2 0 3 tube.
In this case, however, it is very difficult to distinguish
50Ti 13 + from 27 A1 7 + which has almost the same valueof A/q = 3.85 as that of 50Ti13+, where A and q are
the mass number and charge state of the ion. For thisreason we have chosen a Si0 2 tube. The support gas
was oxygen. The vacuums of the first , second, and extraction stages were 7.0 x 10- 6 , 5 X 10- 7 , and 8 x 10- 8
Torr, respectively. The microwave power supplied in
the second stage was 600 W. Figure 2 shows the charge
state distribution as a function of the analyzing magnet
current. The ECRIS was tuned for producing 50Ti13+
ions. The 50Ti ions were accelerated by the AVF- Ring
Cyclotron complex up to 80 MeV /u. The beam intensity was 15 ep,A from the ECRIS and 160 enA on thetarget. The consumption rate was 1.5 mg/h.

Tuned for SOri 13+
Extraction voltage
Support Gas 02

10 kV

c

'(j)

c

Q)

C
E
CO

Q)

CD

~
~

'00
c

(])

Analyzing Magnet Current (arb. unit)

C
E 10

ro

Fig. 2. Charge state distributions as a function of analyzing magnet current. The source was tuned for producing the 50Ti 13+ ions.

(])

co

8

10

12

10 12

10 12

14

Charge State (q)Fig. 1. Charge state distributions of Ti ions.

References
1) T. Nakagawa, T. Kageyama, A. Goto, M. Kase, and Y.
Yano: Jpn. 1. Appl. Phys., 32, L1335 (1993).

207

RIKEN Accel. Prog. Rep. 29 (1996)

Present Status and Future Plans of RIKEN 14.5 GHz CapriceY. Kanai, Y. Nakai, K. Soejima, T. M. Kojima, T. Kambara, and Y. Awaya
We have installed a 14.5 GHZ Caprice at RIKEN
as an ion source of the low energy highly charged ion
facility. With this facility, we are planing to study ionatom collisions and ion-surface interactions. We haveconstructed the beam line from the middle of December in 1994 and started to operate the Caprice in the
middle of January in 1995. Here, we show the present
status of this facility and future plans.
We have constructed the beam lines as shown in Fig.
1. Our Caprice source uses a double wall chamber anda 1.2 Tesla hexapole magnet. Details of the Capriceitself are presented in separate papers. 1 ,2) The performance of the 14.5 GHz Caprice has been measured at
Grenoble and also at RIKEN. Typical intensities ofions from the Caprice at RIKEN are shown in Table 1.

Table 1. Typical ion currents from RIKEN 14.5 GHz
Caprice.
Ion

Currents(e~)

Ion

+1

+2

+3

+4

+5

+6

N

1000 1100

700

680

560

95

0

1430 1310 1000

700

500

Ar

+7

41

+8

+9 +10 +11+12 +13 +14 +15 +16

360

162

15

39

5

2

0.05

Fig. 1. Schematic drawing of low energy highly charged
ion beam line. ECRIS: 14.5 GHz Caprice, EZ: einzel
lens, AM: analyzing magnet, TQ: triplet quadrupole
magnet, SW: switching magnet, FC: Faraday cup, 14.5
GHz rf generator, PSI: power supply for mirror coils,
PS2: power supplies for beam transport magnets.

line and the plasma chamber, which means the extraction potential , is kept constant, and the potentials of
the plasma chamber and a beam line are changed depending on the beam energy that we need. 3 ) To use thismethod, (1) we made the whole beam line between the
Caprice and the point just after the switching magnet
to be isolated from ground potential, and (2) we modified the insulator of the extraction part of the Capriceto isolate the beam line from the plasma chamber of
the Caprice. Power supplies of the magnets for the
beam transport system and the beam diagnostic system, which are isolated from ground, are controlled byusing an optical fiber system. The various kinds of ionshave been transported to the experimental chamber atthe 30 degrees beam line with keeping the potential of
the isolated beam line to ground potential. A test of
the whole isolated system will be made in this winter.
For the first experiment, we are planning the electron spectroscopy of the doubly-excited ions producedby the multiple electron transfer processes. 4 )These ion currents were measured by a Faraday cup after an analyzing magnet, shown as FC in Fig. 1. These
values are smaller than the maximum ion currents reported by Grenoble group. This may be due to themisalighment between the Caprice and the beam line.
We are planning to use the ion beam in the energy
range of 1-20 x q keY; q is the charge state of ions.
To get lower energy ions (1 x q ke V) , we used such amethod that the potential difference between a beam

References
1) D. Hitz et al.: Nude. Instrum. Methods Phys. Res.,
B98, 517 (1995).
2) D. Hitz et al.: Proc. 12th Int . Workshop on ECR Ion
Sources, RIKEN, p. 126 (1995).
3) B. Martin et al.: Proc. 11th Int. Workshop on ECR Ion
Soueces , Groningen, p. 188 (1993).
4) Y. Kanai et al.: Nucl. Instrum. Methods Phys. Res. ,B98, 81 (1995).

208

RIKEN Accel. Prog. Rep. 29 (1996)

E-Field Injection for Extracting Much Faster Pulse Trains or for
Enhanced CW Beams out of an ECRIS Potential-Well
M. Niimura, T. Kageyama, T. Nakagawa, A. Goto, and Y. Yano
An alternative upgrade technology was developed
by applying the key physics identified as responsible
for upgrading the ECRIS beam-current. The electric(E-) field injection method proposed here can produce not only faster pulse trains than achievable bypresent techniques but also upgraded beam intensity at
low emittance beyond the level of electron (e-) beam
method. The goal is a pre-bunched ECRIS injector
usable for fast timing linacs as well as synchrotrons,
yet operable in an efficient CW mode for cyclotrons.
Here, we present its underlined physics and conceptual
design, where an intensive ('" = 169 at Z = 15), fastpulsed (sub-microsecond), yet low-emittance (rv 10- 7 1Tm rad) beam can be expected.
Presently available pulsing techniques need to destruct the confinement of ECR-heated electrons by either turning off the RF field (afterglow mode) or pulsing the mirror magnetic field (PuMa mode). These
techniques rely on the diffusion processes of charged
particles for its extraction, thereby making the production of a fast pulse train unable nor of a shortpulsewidth. E-field, on the other hand, can extract
ions by the drift process, a faster transport than diffusion. The method won't perturb the electron confinement nor destruct the ECR potential-well.
Our idea is to increase the end-loss current,
Ib = 10 exp{ -Ze~¢/kTiz}, without lowering the potential barrier ~¢. Petty!) has attempted to increase
the end-loss or spill current of particular Z ions byraising its temperature T iz via ion cyclotron resonanceheating (ICRH); only 25% of beam enhancement wasobserved. This was, however, predictable since ICRH
can increase the radial transport (to walls) of ions dueto the increase of Larmor radius. Nevertheless, this experiment has indirectly confirmed the existence of an
ion-trapping potential-well and prompted us to propose a new way of extraction. In our device, ions
are supposedly accelerated only one-dimensionally byan axial electric field Ez without heating the Tiz, yetraising the directed energy enough to overcome the~¢.
Then, the end-loss current may be describedby Ib = 10 exp{ -Ze~¢/[kTiz + ZeEzZp]}. An improved
emittance can be expected because our method can extract even the kT iz = 0 ions trapped in the bottom of
potential-well. The technology needed here is to accelerate only the trapped ions without losing the resonantly heated hot electrons out of the ECR zone. In
order to estimate such a proper range of E z, following
theoretical background was needed.
Forces on Elecrons and Ions Inside the Mirror Magnetic Field (MMF): The force (eEz) to be applied ex-

ternally with the purpose to extract only the ions has
to be much smaller than the magnetic confinement
force exerting on electrons, but has to be larger thanthat on ions inside the MMF. Consider an electron
gyrating around the axisymmetric B-field whose intensity increases gradually towards the direction of +z
a.-xis. Then, in the cylindrical polar coordinates, there
exists the radial component Br since the field lines
are gradually compressed towards +z axis. The electrons with azimuthal velocity Vee interact with the Br
to experience an axial force: Fz = -e [vexB]z = eveeBr
since Be = O. The Maxwell equation, V . B=O, expressed in the axisymmetric system (8/80=0) is in theform: rBr = - r(8B z/8z)dr. This integral equation
gives Br ~ -(rLe/2)(8Bz/8z) for r::SrLe if the 8B z/8z
can be assumed constant for r as large as the electron Larmor radius, rLe == vee/wee. Therefore, themagnetic confinement force on electrons is given by
F z = -(eveerLe/2)(8Bz/8z). Since Wee == eB/m, theaxial equation of motion is

J

dVze
8B
mill
=-J.Lea;:'
z

_

mVOe

2

J.Le= ~

()

~o.

(1)

Equation 1 states that the electrons in the region where
8B z/ 8z ~ 0 experience the force F z = - J-Le ( 8B z/ 8z) of-z direction (towards the midplane, z = 0). The magnitude of F z is proportional to the magnetic moment ofgyrating electrons, J-Le. This means that the force exerted on electrons, -eEz should be much smaller thanthe electron confinement force - J-Le (8Bz/ 8z). Namely,
their magnitudes should satisfy the condition:eE z «

J.Le (8B z /8z).

(2)

Since Vze = dz/dt, we can rewrite the equation of
motion (1) as (d/dt)(mv ze 2/2) = -J-Le(dBz/dt), andthe definition of J-Le as mvee2/2 = BzJ-Le.
Therefore, the constraint of constant total kinetic energy, dW /dt == (d/dt){m(v ze 2 + v eq 2 )/2 = 0 can be
expressed as -J-Le(dBz/dt) + (d/dt)(BzJ-Le) = O. From
this, the invariance of J-L can be derived as dJ-Le/dt = O.
Since W z = 0 at the turning point (B = B R), the invariance of J-Le tells that J-Le = W /B R. This BR shouldbe equal to B ECR which forms the ECR surface because the largest azimuthal energy Wemax is generated
at this surface. Should a particle move along the Bfield line to a location B ~ BEcR, the magnitude of We
has to increase beyond that of W emax due to the invariance of J-Le, which is unlikely. Thus, electrons aremagnetically confined by MMF, whose volume is called
ECR-zone or -egg.
Let us evaluate Eq. (2) numerically. For a 10
GHz ECRIS, the B-field at the turning point is
BR ~ B ECR = 3.57 kG. So, if Bmirror = 10 kG we havethe mirror ratio M ~ (Bmirror - BEcR) /BECR = 1.80
209

assuming Bmidplane ~ B ECR . We also assume the characteristic length of mirror field to be Llz = 10 cm,
and the kinetic energy evaluated at B = BECR to bemVe 2/2 = 500 eV. Then, Eq. (2) gives the condition:
Ez«

~B 1
-1 rnve 2 - - = gOV/ern
2e(3)

BECR ~zOn the other hand, the ions are usually not wellconfined inside of MMF because its Larmor radius rLi
is often too large. However, under ECRIS conditions,rLi/rLe = (MTdmTe)1/2/Z:::; 10 even for Ar ions because TdTe:::; 1 and Z 2: 10 are typical. This implies
the situation rLi ~ rLe. Then, (8B z/8z) can be constant for r :::; rLi. This means that the axial force onions is in a similar form: 2) Fz = -I-Li(8B z/8z), where
I-Li == MVOi2 /2B ~ kTi/B ECR . Obviously, I-Ld I-Le:::; 1/10
and this imbalance helps to extract the ions selectively
with a small external force: ZeEz 2: I-Li(8Bz/8z). The
minimum Ez necessary to extract ions from MMF canbe calculated by
12 ~B
1Ez> -MVOi - - -2Ze

BECR ~zFigure 2a shows a conceptual design of the new
ECRIS injector. The Ez will be induced externallyacross the ECR potential-well via a betatron-likemechanism. In order to secure the low-emittance beam
extraction a drift tube with a griddle front entrance
will be used. The tailored electric field lines are to
avoid electrons from entering the loss cone. In the CW
mode of operation, an e-beam emitted from the biaseddisk like cathode is used, but injected in the direction
opposed to that of conventional e-beam injection. In
this way the . b.¢ at the side of extraction electrodewill be lowered , thereby mitigating the ion loss takenplace during the transport. Figures 2a and 2b show
the motions of charged particles inside of MMF and of
potential-well, respectively.
6¢l =20eV
6¢leb= IOeV
kTi = 50eV
E =4V/emz( )= O.gOV/ern

4

Ip = 5 ern..•.....•.....

Here, MVOi2/2 = 50 eV was assumed beside the conditions used above. The Ez not to disturb electron
confinement is thus in the range:
0.90 ~ Ez «90.

(5)

(V /ern)

Directed Energy Gain of Ions Inside an ECR
Potential-Well: Beside satisfying the condition (5) , theEz needs to give enough energy for trapped ions to
overcome the Ll¢ in its extraction:
Ez ~ ~¢/Zelp ~ O.4[V /ern],

lp ~ 5 em

Ze~¢

kTiz + Ez lp

1/ exp [ze~¢]
- kT
iz

(7)

Figure 1 graphically shows the calculated 'rJ E as a function of Z, together with the case of e-beam injection: 'rJe(Z) = exp(eb.¢ebZ/kTiz) = exp(0.2Z). A drastic improvement at higher Z's is evident; 'rJE = 24.5
and 169 (whereas 'rJe = 7.39 and 19.9) at Z = 10 and
15, respectively.
210_.-- ' e-6eam Injection

10

10

IS

20

Charge State. Z

Fig. 1. Upgrading factors "1 achievable with E-field injection in reference to the case of e-beam injection.

(6)

For the numerical evaluation of Eq. (6) we have referred the e-beam injection experiment conducted at
LBL. 3 ) The e-beam injection has lowered the height ofthe positive (or peripheral) plasma potential V p (whichis the electric potential measured with respect to thewall potential). It is equivalent to lower the height ofbarrier of the potential-well, b.¢. They were successful to lower V p or b.¢ by approximately 10 eV, which
implies that the e-beam potential was b.¢eb = 10 eV.
Their experiments can be well explained if Z = 10
and b.¢ = 20 eV are assumed. Further, lp ~ 5 cm
was assumed in Eq. (6) as an effective acceleration
length which corresponds to a half length of the typical ECR-zone.
As an appropriate Ez to satisfy the both conditions(5) and (6), we chose Ez = 4 V / cm. This number together with the values used above has been substituted
into the formula of upgrading factor of the E-field injection:"1E (Z) = exp [-----_ ..

--.--(a) E - Field lad.Clio. Cu.:-il for Fast- ....se 10. Beaa EnraClio •.

·L

.I p

0

Ip

L

(b) Priaciple of E - Field Enrac:tio. of lou froa Poteatial- WeU.

(c) Y"C.eticaUy Trapped Dot Electrou D.~. UeE.« Jl . flBM z).

Fig. 2. A conceptual design of (a): E-field extracting,low-emittance pre-bunched ECRIS injector, where (b):only the ions are extracted out of ECR zone, whereas(c): the hot electrons are kept trapped inside of MMF.

References

1) C. C. Petty et al.: J. de Physique, 50, Cl-783 (1989).
2) A. Irani and N. Rostoker: Particle Ace. , 8, 107 (1978).
3) Z. Q. Xie et al.: Proc. ECR-ll , p. 996 (1993).

RIKEN Accel. Prog. Rep. 29 (1996)

Supporting Evidences of the LLPB Concept to Explain Enhanced
High-Charge State Ion Beam-Current in ECRIS
M. Niimura, T. Kageyama, T. Nakagawa, A. Goto, and Y. Yano
Progress was made in identifying various experimental evidences to support the concept of local lowering of potential barrier (LLPB) which can explain
the beam-current upgrade mechanism in an ECR ion
source (ECRIS). A threshold like behavior observablein the upgrade experiment was found due to the effectof the peripheral-plasma (PP) surrounding an ECRplasma. This suggests two sources (peripheral and
ECR plasmas) of producing ions in a single ECRIS
device. The background theory was thus extended forthe two-source model and was treated by a more realistic spherical (rather than cylindrical) model for simulating an ellipsoidal ECR-egg. Finding the non-trivial
roles of PP, its parameters were estimated by applying
an electrostatic probe theory on available experimental
data. The PP electron temperature (Tee) of RIKEN
10 GHz ECRIS was found to be 70 172 eV.
Extension of Background Theory: Here we introduce a spherical model followed by a theory of twosources. From the Gauss theorem,
E . ndS = ~q/eQ'
the E-field induced by the uniform space charge(~q == pdv = 47rr 3 p/3, where p = -nee) inside a
spherical ECR-volume of radius "a" has the radial
component, Er = pr/3eQ for r ::; a. Here, "a" is determinable by (S/47r)1 /2 using the surface area S of areal ECR-volume. The Er is negative since the potential of spherical model is ¢(r) = (r / a)2 t::,.¢, which isparabolic like the case of a charged cylinder except thebarrier height t::,.¢ == ¢(a) == n eea2/6cQfor the sphericalmodel. While the resonant electrons are magneticallyconfined (due to the large perpendicular magnetic moment) to create the space charge, the ions are confined
only by the space-charge potential (gradient) force,-Zen z\,7r¢(r) , inside the ECR-egg. Thus , the radial
equation of motion of the trapped ion mass-density isz
Mll z dv = -V'rllz(r)kTiz - ZellzV'r ¢(r), V'r == a/or
(1)
r-.J

Is

I

dt

Spatial integration of Eq. (1) at the steady-state (ss) gives nz(r) = nz(O) exp[-Ze¢(r)/kT iz ] == nz(O) exp(-Kr 2).
Here , K == Ze2ne/6cokTiz and nz(O) isthe s-s ion peak density at the midplane (r = 0,
¢ = 0). The nz(r) obtained right above indicatesa Gaussian distribution of n z. The ion density at
the surface of ECR-volume is thus given by nz(a)= nz(O) exp[-Zet::,.¢/kTiz] == nz(O) exp( -Ka2). The
spill-flux, fa == vinz(a), crossing over the potential barrier t::::.¢ isr a = Villz(O) exp (- zet::..¢ ) , Vi == J2kT iz /7rM.
(2)
kTi z

Here, the exponential term represents the probability
for the ions of charge state Z and temperature kT iz tocross (or spill) over the t::,.¢. See, Fig. l.
If n z ions were produced only inside the ECR
sphere [Single-Source Theory], the extracted beam-

Fig. 1. A "chipped dogfood bowl" like potential distribution inside an ECRIS, illustrating the LLPB concept
and the two sources for ion production.

current (I ext ) should be equal to the spill-current:
Iext = Ia == ZeSaf a, where Sa == 47ra 2. Since nz(r) has
readily been derived from Eq. (1), the volume-averaged
density is rigorously calculable. Here, however, themost simple-minded approximation, (n) ~ n z (0)/2, isused for simplicity. Then, the total number of ionscontained inside the sphere is N == Va(n) ~ V a n z(0)/2.
Therefore, the continuity equation, aN/at + Saf a= Q , gives anz(O)/at + 2Saf a/Va = Q; where Q is
the supply term. Since r a is given by Eq. (2) and
Sa/Va = 3/a for the spherical model, we haveallz(O) +llz(O)= Q.
at(a/6vd exp[Zet::..¢kTizl(3)

If Q = 0, the particle loss can not be offset. The homogeneous (Q = 0) solution of Eq. (3) gives the ion
confinement time relevant for spherical ECR plasmas:atnz(O) = nzo exp --;. 'T== 6Vi exp(zet::::.¢)
kT
(4)

iz
The spill-flux can then be written as r a = (a/6T)n z(0);thus r a ---+ 0 as T ---+ 00 no matter how large thenz(O) is.
Two-Source Theory: Now we take the PP into
consideration. As for its container, we assume acylindrical magnetic bottle with length Lc (chamber length or magnetic mirror separation, whichever
shorter) and volume V c (> > Va) . The non-resonant
electrons as well as ions will diffuse out of the mirror magnetic field (MMF) if the pitch angle is smallerthan== sin- 1(Rm - 1/ 2), where Rm is the mirror
ratio , thus creating a positive ambipolar potential(¢ A) in order to accelerate ions parallel to the MMF.
Charged particles are lost only through the ends ofcylinder whose area is 2S end. No cross-field diffuThe amsion is allowed throughout this paper.
bipolar diffusion equation, an/at = D A\,72n, can besolved by using the method of separation of variables
to obtain n z (z, t) = nz(O, 0) exp( -t/T) cos( 7rz/Lc) and
Here, DA = (1 + Te/Ti)Di being
T = (Lc/7r)2 /D A.

em

211

Di = kTi/Mvin- For the ECR pressure range (rv 10- 6Torr), the mean-free-path, MFP == Vi/nin, is much
longer than L e/2 so that the ion-neutral collision
frequency is effectively Vin = 2Vi/Le, thereby giving
Di = ViLe/2. Thus, we obtain the ion confinement timeof PP as T = 2(Le/vi)7r-2(1 + T e /T i )-l ~ (L e/10vi)
This gives T = 3.2 J-lS being
if Te/Ti ~ 1.
Vi = (kTi/M)1/2 = 1.55 X 106 cm/s if Ti = Te = 100
e V for argon ions and Le = 50 cm.
However,
T = Le/2vi = 16 f.1,S if the n z distribution was uniform.
Such T is measurable in the afterglow mode from thesignal delay time of the high charge state ions produced
at the midplane.
The above study indicates that T of PP is not a function of Z and rather short. Therefore, PP can produce
only the LCS ions lower than Z::; ZOo Here, the critical
Zo is predictable as the maximum Z that PP at Tee canproduce by the time T. In the domain Z::; Zo, the T of
ECR-plasma can be much smaller than that of PP due
to the small Z and small "a" as seen in Eq. (4); thereby
giving Iext == Ia + lend ~ lend. When the sheath edgeof the extraction port locates at z = s « Le/2), we
can write lend = ZeSsfs and rs == vBn s , where VB ==(kTe/Mi)1/2 is the Bohm velocity. Since ns ~ 0.61nz,
we obtain lend = 0.61ZeS svBn z(a) cos(7rs/Le)' As forr a of Eq. (2), only a half of the flux is directing towards z = s, and Ia > > lend for Z ~ ZOo Here,Zeb.¢
la = 0.31 ZeSsvBnz(O) exp(---)
kTiz

(5)

If the tl.¢ was lowered by the amount tl.¢eb due to, say,an e-beam injection, Eq. (5) gives
Ia = 10 exp[-Zeb.¢ - b.¢eb
kT z

1 rv exp(b.¢eb)(6)

where 10 == 0.31ZeS svBnz(0). The upgrading factor defined by 'r] == Ia(tl.¢eb =1= O)/Ia(tl.¢eb = 0) IS therefore
scaled bylo(b.¢eb i= 0)[Zeb.¢eb][1(7)
rJ = Io(b.¢eb = 0) exp

~

rv

exp z

for Z above the threshold, ZOo Experimental datal)
show a good fit with 'r](Z) rv exp(Z - Zo) in the domain
Z~Zo·Experimental Evidences in Support of the LLPB
Concept are: (A) Exponential growth of the extracted
ion beam current observable in the plasma cathodeand biased-disk experiments 1); i.e., Ib rv exp (V) ata fixed Z for the negative bias voltage V. This isa direct proof of the LLPB concept. Since the ebeam current extractable from the plasma cathodeobeys Child-Langmuir law Ie = Const V1. 5, the electrostatic potential of e-beam can be expressed by~¢eb == Const I e/Vo. 5 = Const V. Therefore, from Eq.
(6), one should have Ia == Ib rv exp(~¢eb) rv exp(V),thus confirming the lowering of potential by theamount of ~¢eb. (B) Existence of Zo in the plot of'r](Z); i.e., 'r] rv exp(Z - Zo). This indicates presenceof two sources for ion production. No clear threshold in Z should be observable without a PP. (C) Goodagreement of experimental data with the scaling laws;'r] rv exp[Z] when ~¢eb is fixed. This suggests that kTiz212

is independent of Z in the first order approximation.
Further, the scaling law 'r] rv exp[~¢eb] for fixed Z indicates that 10 won't change by ~¢eb. This means thatnz(O) as well as Tee is not disturbed by the injectionof e-beams. This supports the localized event of thepotential lowering; if it were not in the perturbation
order, the nz(O) would deteriorate during the e-beam
injection, thereby saturating 'r](Z) curve prematurely.
Characteristics of PP: When a biased-disk or acathode-plasma-supporting conductive-wall is biased
by a negativ~ potential (V) more negative than the
floating potential (V F), a forward electric-current
is drained from the conductive surface as much as
I = lis - Ies exp -e (Ves - V)/kTee' Here, the suffixes'is' and 'es' denote the ion and electron saturations,
respectively. Using the condition 1=0 at V = V F ,we obtain In(Iis - I) = lnl is - e(VF - V)/kTee. We
have converted the V-I data of biased disk andplasma cathode experiments 1) into the (V F - V)
vS. In(I is - I) data and replotted them on a semilogarithmic graph.
The Tee has been calculated
from the straight line obtained, since its tangent
ought to be -e/kTee . We found Tee = 29.5 eV and
VB = 9.79 x 105[Tee(eV)/ A]1 / 2 = 8.42 X 10 5 cm/s forargon ions in the PP of Mini-Mafios ion source;2)Since lis == ZeSnz exp( -1 /2)(kT e /M)1 / 2 is experimentally observable, the ion density was calculable asn1(cm- 3) = 8.48 x 10 13 I is (Amp)/[T e (eV)p/2 for
Z = 1 argon ions assuming S = 0.785 cm 2. The n1
gave the electron number density since ne == :EZn z,
with which the maximum e-beam current extractable from the PP plasma has been calculated as
les == O.25eneS(8kTe/7rm)1 / 2 = 1.32 x 10 - 12 n e (cm- 3 )[T e (eV)J1/2 [A]. Figure 2 plots these parameters, together with the maximum ion beam-current (I bmax )extracted,l) for RIKEN 10-GHz ECRIS. Rather highTe is evident. Notice that all parameters are exhibiting the same pressure dependence in both domains if
a jump between the domains of plasma-cathode andbiased-disk is neglected.
r-r-r-,.......,......-,--,.~---r-~---,-r-r-,

PI _ _ CatIoocle.... '\

Arll +~ Biased Disk~........

~~~-~-~-~~~

'5

~

10

~

inmA

~m""infLA
/'

C

>

I

.r

\

nj in 10\,-_J£-~

10

em

-3

f-"

10

20

30

40

50

Pressure. p [~Torr1

Fig. 2. Semi-experimental PP-parameters of an ECRIS.

References
1) T. Nakagawa et al.: Jpn. J. Appl. Phys., 31, L1129(1992); ibid., 32, L1335 (1993).
2) B. Paul: Patent, Int. Cl. 9013232, Oct. 25 (1991); JP589792, Apr. 9 (1993).

RIKEN Accel. Prog. Rep. 29 (1996)

Development of Polarized 3He Gas Target
T. Uesaka, T. Wakui, and M. WakasugiWith the test bench constructed last year , 1) the polarized 3He gas target that is produced by a spin exchange reaction with optically pumped Rb atoms has
been studied.
The polarization of 3He was observed with an adiabatic fast passage NMR polarimeter; the result isshown in Fig. 1. The experimental conditions are listed
in Table 1.

I

I:::
0

-

• • • • •

:.:;

• •

I

I

I

•
•

•

•• •
-

•

«l
N

•

.J:::
«l

'0

-

•

-

•

0..
Q)

:>

' :;;
«l

a>

-

• •

~

-

L

I

I

1

15

20

25

30

Magnetic Field [arbitrary unit]

Fig. 1. Observed NMR signal.

Table 1. Experimental conditions. 1 amagat corresponds
to 1 atm at 273 K.
Cell material
3He density
N2 density
Cell temperature
Holding field
RF frequency

Corning 1724
3.3 amagats",0.13 amagats
180 ° C",25 gauss
82 kHzInstead of measuring the absolute polarization, thespin relaxation time is used to evaluate the cell, because it is very difficult to calibrate the absolute polarization. To measure the relaxation time, time dependence of the polarization has to be measured. The

relaxation time, however, was too short to measure andthe polarization disappeared in a few seconds. To solve
this problem, two kinds of modifications to the target
system were made.
One is for a glass material of the target cell. Corning1720 has been known to be a good material for thepolarized 3He target cells. However, it is no longer inproduction. Therefore at first we started with Corning1724 which is also aluminosilicate glass as Corning1720. KEK group and one of the authors tested
Corning1724 cells at KEK Booster Synchrotron Facility. The result showed much shorter relaxation time forCorning1724 than for Corningl720. We thus gave up
Corning1724 and then employed Corning7056, which
was reported to show comparable relaxation time toCorning1720 by Michigan group.2)
The other is for the cell making apparatus. Fromthe investigation performed in collaboration with KEKgroup, a gas purification method was found to play animportant role to achieve long relaxation time. 3) Following this result , two chemical getter gas purifiers for
3He and N 2, SAES Getters GC50s, have been introduced. GC50's reduce almost all the impurities to lessthan 10 ppb.
In spite of these modifications , however, the relaxation time was still of the order of 10 seconds. This
short relaxation time is considered to be due to a large
surface-to-volume ratio of the cell. The problem will
be reduced in the next target system with a larger target cell. Also the calibration of the polarization by the
proton NMR method will be easier with the large cell.
Construction of the new system is now in progress.
Measurement of the 3He polarization is planned earlyin December 1995.
References
1) T. Uesaka et al.: RIKEN Accel. Prog. Rep. , 28, 154(1995) .
2) K . P. Coulter et al.: Int. Symp. Polarization Phenomena
in Nuclear Physics, Bloomington, U.S.A. (1994).

3) T. Uesaka et al.: Proc. Int. Workshop on PolarizedBeams and Polarized Gas Targets, in press.

213

RIKEN Accel. Prog. Rep. 29 (1996)

Development of a New Type of Single-Bunch Selector
N. Inabe, M. Kase, 1. Yokoyama, A. Goto , and Y. Yano
A system to produce a single-bunched beam, which
was reported in the last progress report,l) has beendeveloped so as to increase intensity and quality of thebeam. As concern to the quality, main purpose is toraise up purity that is a ratio of current of the desired
bunch to total one including undesired bunches.
Figure 1 shows a method to produce the singlebunched beam.
As shown in Fig. 1, the singlebunched beam can be produced by sweeping undesirable bunches transversally and/or longitudinally. In
the old system only the transversal sweeping is done
by a chopper with parallel plate electrodes. Because,in our method, sweeping is done for the continuous
beam with a low energy from the ion source (extraction voltage < 10 kV) , a base of the single-bunchedbeam, that is a remaining part which is not swept , hastails inevitably as shown in Fig. 1. Origins of the tailare a traveling time that the beam is passing throughthe electrodes with low velocity as well as a rise andfall time of the voltage supplied to it. In order to produce the pure single-bunched beam the tails should
not overlap with the acceptance of the next bunch to
the desired one. However, as it is difficult to shorten
the tails for technical reasons , there is a limitation to
produce the pure single-bunched beam in this way.
Continuum beam fromthe ECR ion source

Beam picking up by the
chopper
Acceptable bunchesof the AVF cyclotron
with the buncher
Single Bunch Mode.. (1 ~~ .~.0~~) ..

(Normal mode)

I

I

I

:

Single bunched beamfrom the AVF cyclotron( ;.'.: swept bunch)

Fig. 1.
beam.

Production mechanism of the single-bunched

For the reason mentioned above longitudinal sweeping was also introduced in the system. The longitudinal sweeping can be done by making phase acceptance of the undesirable bunch at the buncher narrow. For the purpose, we used the buncher with subharmonic mode. Figure 2 shows the phase acceptancefor the sub-harmonic mode and the normal one. For
the sub-harmonic mode the phase is modulated by asine-shaped wave that we used. As shown in Fig. 2, theacceptance is wide when the phase is compressed and214

Beam Sweeping by Sub-harmonic Buncher
I Norma I mode I
Vo I tage~7~!/'-,i "7/'-, :"J/'-,:" time___

_ _ _.........·_
Voltage

"'"
:
~
~

~
.
1

. . . . _____--'1!"_~-_-_ ______

:

_

---'.
_
---'.
_

.....,.,.---Buncher Acceptance_ __ . ' - -_ ___Acceptance.~AVF_ __ . ' - -_ ___• ___-=Beam from AVF

I Sub-harmoniC mode ( 1/3 f) I
~
;
/
~~
~

time

Fig. 2. Mechanism of phase compression by the buncher.
Upper figure is for the normal mode and lower for the
sub-harmonic mode (f = 1/3).

narrow when that is diverged. A ratio of the narrow
acceptance to the wide one is a few percent. Moreoverthe intensity of the beam for the sub-harmonic mode
becomes higher than that for the normal one because
the compressed phase for the sub-harmonic mode islarger than that for the normal one. Of course, byusing the part of the wide acceptance as the desired
beam the single-bunched beam can be produced but
the purity is not so high.
By combination of the two ways , clearly, the purity of the single-bunched beam can be raised up. Because the acceptance of the desired bunch is wide andthe undesired one, narrow for the sub-harmonic mode,
overlap between the tail and the acceptance of the undesired bunch becomes small. In principle , if the acceptance of the desired bunch becomes wide enough toinclude the tail, the single-bunched beam with the purity of 100% can be produced. In this way the highly
intense and pure single-bunched beam can be producedby both the transversal and longitudinal sweeping.
We used the buncher that has been alreadyinstalled. 2 ) In order to operate the sub-harmonic mode
we must use the buncher at low frequency (4- 8 MHz).
For the purpose we made a new frequency divider
whose amplifier and phase are controllable. A wave
made by the divider is sent to the buncher via a wideband amplifier.
A performance study of the system was carried out
for the 10.0 KeV Arl1+ beam from the ECR ion source
which was accelerated to 5.2 MeV/nucleon by the
AVF with an RF frequency of 14.05 MHz and to 95
MeV /nucleon by the Ring Cyclotron (RRC) with an
RF frequency of 28.1 MHz. The setup is shown in Fig.
3. The voltage between the electrodes was switched
off every 200 ns. Voltage of the electrodes was 200

V. The buncher was operated with the (1/3)f mode.
Time structures of the beam after the AVF and RRC
were measured by using a time of flight (TOF) withthe same method as shown in Ref. 1.

1500~--------------------,

1000

g
o

U

500

O+-~~I----~'~~-~I---'-I~-~I--~I~--'I--~
o
100
200
300
400
500
600
700
Channel (Arbitary Unit)

Fig. 4. An example of time spectra of the beam extracted
from the AVF.

20000
a: Peak from anolher lurn of Ihe RRC
b: Peak from OIher bunch unswepl
by Ihe chopper

15000

~

Trrc : An RF priod of Ihe RRC

U

10000

5000

Fig. 3. Setup for a performance test of the single-bunch
selector.

6<Trrc6X[rrc

6Xfrrc

Wrrc

400

600

800

[ r 5xTrrc
b a

200

1000

Chan nel (Arbilary Unil)

Figure 4 shows a typical example of the TOF spectrum of the AVF. As shown in Fig. 4, the purity of thesingle-bunched beam is almost 100%. Figure 5 shows
an example of the TOF spectrum of the RRC. The
main peak in Fig. 5 is made by the single-bunchedbeam to be extracted. The other peaks are originated from another turn of the RRC (a) and next mainbunch (b). The production mechanism is shown in Ref.
1. By careful tuning of the RRC we can extract thebeam with single turn. In fact , we supplied t he single
bunched beam of which purity was more than 99%.
The current of the single bunched beam from the RRC
is rv20 neA.

Fig. 5. An example of time spectra of the beam extracted
from the RRC. T rrc means the RF period of the RRC.

The obtained intensity is rather smaller than theestimated one. It might be due to bad transmission of
the RRC because the electric injection channel did notwork sufficiently. A detailed study will be performed.
References
1) N. Inabe et al.: RIKEN Accel. Prog. Rep., 28, 160(1995).
2) K. Ikegami et al.: ibid., 22, 213 (1988).

215

RIKEN Accel. Prog. Rep. 29 (1996)

Construction of a New Beam Line from the AVF Cyclotron
N. Inabe and M. Kase
A new beam line (E7E) has been constructed in theexperimental room 7 (E7) for users of AVF cyclotron(AVF). Before the new construction, as shown in Fig.
1, the E7 room already had lines for beams from the
AVF (E7C and E7D) other than those from the RIKEN
Ring Cyclotron (RRC; E7A for SLOW and E7B for
Large n). However, since the main space in the E7room was used for the beam lines E7 A and E7B, theexperimental area of the beam lines E7C and E7D wasvery small. Especially, due to the small space, it was
impossible to perform a newly proposed experiment ofa polarized deutron beam from the AVF.1) To solve a
problem of the small space, it was needed that a newbeam line with a large experimental area was to beconstructed instead of the E7C. Recently experiments
using the Large n have been finished. Under the situation, we removed the Large n and constructed the
new beam line (E7E) in the area used for the Large n.

From ECRIS / PIS

Optics in the new beam line was calculated using
the computer code TRANSPORT. A required beamspot size is less than 4 mm. To meet the requirement
we searched the parameters. In the calculation theemittance of the beam extracted from the AVF wasassumed to b~ the one that had been measured. 2 ) The
obtained values in the downstream of the DMC7 magnet are summarized in Table 1. The beam envelope isshown in Fig. 2.
Table 1. Parameters of the new beam line.
Drift length (m)DMC7 rv 1st Q of the QTE7
1st rv 2nd Q 's of the QTE7
2nd rv 3rd Q 's of the QTE7
3rd Q of the QTE7 rv target
Effective length (m)1st and 3rd Q of the QTE7
2nd Q of the QTE7
Max. field strength of Q (kG/em)
all three Q 's

2.7
0.2
0.2
2.0
0.25
0.45
1.5

(em) 6

6
QTCOI

Fig. 1. Schematic drawing of the AVF and E7 room. The
dark grey part is the new beam line and the dotted partis the old beam lines.

The newly constructed beam line is the downstreamof the dipole magnet (DMC7) as shown with dark greyin Fig. 1. The DMC7, which has been used in the E7C,
has been rotated by 90 degrees in counter-clockwise direction. The removed beam line of the E7B has beenused in the E7E by adjusting the length of a beam ductin the upstream of the quadrupole magnet (QTE7).
The new beam line has a Faraday cup and a profile
monitor in the downstream of the QTE7 and steerer
magnets in the upstream of the QTE7. The experimental area is now large enough to perform the experimentmentioned above.
216

QDC02 DMCIQDCII DMC7

TargetFig. 2. Envelope of the beam in the new beam line.

Last April an 8 MeV polarized deuteron beam was
firstly transported in the new beam line. The obtained
beam-spot size was about 4 mm. Transmission of thebeam from COl to the target point was more than 80% .
Until now several users have done experiments inthe E7E using not only the polarized deuteron but also
other kinds of ions.
References
1) N. Nishimori et al.: This report , p. 58.
2) N. Inabe et al.: RIKEN Accel. Prog. Rep. , 28, 158(1995) .

RIKEN Accel. Prog. Rep. 29 (1996)

Improvement of the RF Control System for RILAC
s. Kohara, E. Ikezawa, M. Hemmi, T. Chiba, T. Aihara,* T. Ohki,* H. Hasebe,*
H. Yamauchi,* and Y. Miyazawa
The rf control system for six resonators of RILAC
was improved to get easy maintenance and stable operation in this year. The amplitude controller and theautomatic tuning circuit were newly designed, fabri-cated and installed for each resonator of RILAC.
A block diagram of the rf control system is shownin Fig. 1. It consists of a three-stage power amplifier and the low level circuits. 1 ,2) The operational freFrom voltage pickup

To other five rf systems
and bunchers±5V

Automatic tuning

Level reference
voltage' - - - - - - - I. . circuit

From grid pickup

Fig. 1. Block diagram of the rf control system.

quency range of these controllers is from 17 to 45 MHz.
The amplitude controller operates to excite the resonator in the three modes; pulse, cw-pulse and cwo The
pulse mode operation is employed to find a resonancecondition of the resonator by moving a capacitive trimmer manually and to overcome the multipactoring phenomenon in the resonator tank. The pulse width andrepetition cycle can be varied from 1 to 10 ms and from
0.5 to 10 Hz, respectively.
After the cw-pulse mode is selected, the pulse operation is automatically changed into the cw one when theaccelerating voltage of the resonator reached more than
30 k V. The accelerating voltage is regulated with theamplitude controller by comparing the pickup voltage
from the resonator and the level reference voltage. In
this mode, the cw operation is automatically changed
into the pulse one when the accelerating voltage is lostby the vacuum discharge which occur in the resonator.
In order to easily recover the accelerating voltage theoutput level of the amplitude controller in the pulse
mode operation is set about 1.2 times higher than thatin the cw mode operation.
The cw mode operation is employed to adjust the
impedance of the tuning circuit for the input and theoutput of the final amplifier (RCA 4648). The feedback signal of the accelerating voltage is fed to thephase-lock circuit via the amplitude controller.
The tuning of the resonator is maintained automatically by moving the capacitive trimmer with the autoSumijyu Accelerator Service, Ltd.

matic tuning circuit. The automatic tuning is performed by comparing phases between the plate and thecontrol grid voltages of the final amplifier. When the
output circuit of the final amplifier is tuned to the resonator, the phase difference between the control gridand the plate voltages becomes 180 0 •Output signal of the automatic tuning circuit is fed
back to the servo motor to move the capacitive trimmer. When the accelerating voltage is lost in the res. onator, its output voltage becomes zero to stop thecapacitive trimmer. Maximum output voltage of theautomatic tuning circuit is ±5 V DC.
A variable delay, which had been manually-adjusted
delay lines, was replaced by a phase shifter equippedwith the automatic tuning circuit. The phase shifter
can be variable continuously more than ±180°. These
controllers are connected to a computer in the controlroom.

r------1 :10 inin.

t- .

Fig. 2. Stability of the accelerating voltage measured at
No.5 resonator. The frequency and the voltage are 32
MHz and 230 k V, respectively.
217

The resonator was easily excited with the cw-pulse
mode (2.5 ms, 1.4 Hz) in the rf excitation test. The~
10 min.

Fig. 3. Stability of the phase measured at No.5 resonator.
The frequency and the voltage are 28 MHz and 240 k V,
respectively.

218

amplitude and the phase stability of the accelerating
voltage were measured for six resonators under beamloading. Figures 2 and 3 show the typical results ofthe voltage and the phase stability for No.5 resonator.
Stability of the accelerating voltage and the phase are< 5.5 x 10- 4 and < 0.1 0 , respectively. The amplitude
stability was improved by a factor of 5. The rf control
system has been working well without serious troubles
since the installation of the new circuits.
References
1) Y. Chiba: RIKEN Accel. Prog. Rep., 14 , 120 (1980).
2) T. Kubo: ibid. , 16, 166 (1982).

RIKEN Accel. Prog. Rep. 29 (1996)

Status of a New Injector System for RILAC
A. Goto, Y. Miyazawa, M. Hemmi , o. Kamigaito, T. Nakagawa, M. Kase, T. Chiba, N. Inabe ,S. Kohara, T. Kageyama, S. Numata, Y. Batygin, E. Ikezawa, and Y. Yano
Fabrication of a new injector system for RILAC wascompleted in the spring of 1995. We have made performance tests of the 18 GHz ECR ion source and the
FC-RFQ linac as well as beam acceleration tests in thesystem. Details of the results are reported in Refs. 1
and 2. Figures 1 and 2 show the photographs of the 18
GHz ECR ion source and the FC-RFQ linac, respectively.

Fig. 1. Photograph of the 18 GHz ECR ion source.

Fig. 2. Photograph of the FC-RFQ linac.

Ion beam intensity from the ECR ion source wasmeasured for gaseous elements such as oxygen, argon
and krypton with an extraction voltage of up to 15
kV. Obtained beam intensity of Arl1+ and that of 0 7 +ions, for example, were 160 and 130 ep,A, respectively,
with the RF power of about 600 Wand an extraction
voltage of 15 kV. The beam intensity from the 18 GHz
ECR ion souce was measured to be higher than thatfrom NEOMAFIOS 8 GHz, now used for RILAC, by

one or two orders of magnitude. It is also noted thatthe beam intensity of, for example, Arl1+ ions was
twice higher than that from CAPRICE 14.5 GHz whencompared at the same RF power of 600 W. Pulse mode
operation was also tested and a significant afterglow
effect was seen particularly for heavy ions like krypton
and high charge states: the ratio of the beam intensity
in the pulse mode operation to that in the cw mode
operation was 4 for Kr 20 + ions. A rod for metallic ionsand a plasma cathode have not yet been tested.
The vanes of the FC-RFQ linac have been threedimensionally machined and assembled within the accuracy of ±50 p,m , the value meeting the requirement for good beam transmission. 3 ) The surfaces ofthe vanes were polished with electrochemical buffing
within the flatness of less than 1 p,m. The resonant frequency was measured to vary from 17.7 to 39.2 MHz.
The measured Q-values and shunt impedances wereabout 60% of the MAFIA calculations. From the shunt
impedance measurement, the required maximum RF
power was found to be 26 k W (cw). We have encountered a serious problem on the ceramic pillars used for
fixing the high voltage part on the base plate of theresonator; multipactoring occurred on the pillars at anintervane voltage below 15 kV, and heating due to dielectric losses in a local region of the pillars occurredat an intervane voltage above 35 kV. To fix this problem, the ceramic pillars were redesigned and are being
newly fabricated.
Beam acceleration tests have been performed forAr3 +, Ar 6 + , Ar l1 + , and 0 5 + ions at the frequencies
of 17.7, 26.1 , 34.4, and 39.2 MHz, respectively, and at
the intervane voltage of about 20 kV. The beam velocity after acceleration, which was measured by the TOF
technique using three capacitive pickup probes, was inagreement with the designed value within 1%. The
beam transmission efficiency of 85% at the maximum
through the FC-RFQ linac was obtained from the firsttests. Beam emittance has not yet been measured inthis test.
The performance tests including the beam acceleration tests showed that the beam intensity from the
RILAC is expected to be increased by one or two orders of magnitude. The system is planned to be installed on site next year. A beam rebuncher will also
be installed at that time between the FC-RFQ linac
and the RILAC.
References
1) T . Nakagawa et al.: This report, p. 220.
2) O. Kamigaito et al.: This report, p. 221.
3) Y . Batygin et al.: This report , p. 223 .
219

RIKEN Accel. Prog. Rep. 29 (1996)

Development of RIKEN 18 GHz ECRIS
T. Nakagawa, Y. Miyazawa, M. Hemmi, T. Chiba, N. Inabe, M. Kase, T. Kageyama,
O. Kamigaito, E. Ikezawa, A. Goto, and Y. Yano
Recently, intense beams of medium mass heavy ions,mainly metallic ions, become one of the major requests
in RIKEN Accelerator Research Facility. For satisfying such a request, a new ECRIS is demanded as anexternal ion source of the RILAC-Ring cyclotron accelerator complex. According to the scaling law proposedby R. Geller, the beam intensity increases with increasing microwave frequency and magnetic field strength. 1)
Therefore, the microwave frequency of 18 GHz has
been chosen for the new RIKEN ECRIS. It is connected to a new RFQ linac and used as a new injector
as described in Refs. 2 and 3. The design of RIKEN
18 GHz ECRIS was already described in Refs. 4 and 5.
In this paper, we present the performance of producing
multi-charged ions from gaseous elements.
Figure 1 shows the beam intensities of highly
charged ions produced from a gaseous element.
These results were obtained by using the gas mixing
method. 1) The typical gas pressure of plasma chamber and extraction stage was 1.0 x 10- 6, and 9 x 10- 7
Torrs, respectively. The extraction voltage was 15 kV.
For example, beam intensities of Ar ll + and 0 7 + were
160 and 130 ep,A, respectively. The distance between
the orifice (¢ = 10 mm) and the extraction electrode(¢ = 13 mm) is also one of the important parameters to optimize the performance of ECRIS. It strongly
depends on the condition of plasma, shape of extraction electrode, and charge state of extracted ions. 6) For
RIKEN 18 GHz ECRIS, the best results for medium
charge states of heavy ions (Le., 0 5 +,6+, Ar 8+"-'11+)

0"\

~
~

'en

c:
Q)
10

!D

10

20

Charge State

Fig. 1. Charge state distributions of 0 , Ar , and Kr ions.

220

RIKEN 18 GHz ECRIS(9 max -1.35T)

150

~
=I.

CAPRICE 14.5 GHz~(~. ,,!,.a!. ~.1:~.

n. __::... 100~

• •••GANIL ECRIS4 14.5 GHz./(9 max-1.3 T)•

CAPRICE 10 GHz(9 max - 1.2 T)•••••• •••E••.. CAPRICE 10 GHz(9 max - 0.8 T)••••••

CO

Q)

CO
200

400

600

800

1000

1200

1400

RF power (watts)

Fig. 2. Beam intensity of Ar11+ ion for various ion sources
as a function of RF power.

References

~ 100

C
E
ro
Q)

could be obtained at the distance of about 30 mm.
Figure 2 shows the beam intensities of Arll+ ionsfor 18 GHz ECRIS , CAPRICE (14.5 and 10 GHz) developed in Grenoble,7) and ECRIS 4 (GANIL)8) as afunction of Rf power. All of ECRISs has almost thesame structure and the same volume of plasma chamber. The extraction voltage of RIKEN 18 GHz ECRIS
was 13 kV. For other ECRISs the extraction voltage
was 20 kV. In the figure Bmax indicates the maximum
field strength of the mirror magnetic field. At the same
RF power, the beam intensity increases with increasing
frequency of micro wave and magnetic field strength as
descri bed in Ref. 1.

1) R. Geller: Ann. Rev. Nucl . Sci., 40, 15 (1990) and references therein.
2) A. Goto et al.: This report , p. 219.
3) O. Kamigaito et al.: This report , p. 221.
4) T. Nakagawa et al.: RIKEN Accel. Prog. R ep ., 28 , 165(1995) .
5) T . Nakagawa et al.: Proc. of the 10th Symp. on Accel. Sci. Technol. , JAERI-Conf. 95-021, Ibaraki , p. 224(1995).
6) R. Leroy et al.: Proc. of 12th Int. Workshop on ECRIon Source and their Application , M. Sekiguchi and T.
Nakagawa (eds.), INS-J-182 , Tokyo, p. 57 (1995).
7) D. Hiz et al.: ibid., p. 126.
8) P. Sortais et al.: Proc. of 10th Int. Workshop on ECRIon Sources, F. W . Meyer et al. (eds.) Oml CONF9011136, Oak Ridge , p. 35 (1991).

RIKEN Accel. Prog. Rep. 29 (1996)

Development of a Variable-Frequency RFQ Linac
for RILAC
O. Kamigaito, A. Goto, Y. Miyazawa, T. Chiba, M. Hemmi, S. Kohara,
M. Kase, Y. Batygin, and Y. Yano
A variable-frequency RFQ linac has been constructed as a new injector for the RILAC. This RFQ
will accelerate ions with mass-to-charge ratios of 6 to
27 at up to 450 ke V per charge by varying its resonant
frequency from 17.7 to 39.2 MHz. The RFQ resonator,
based on a folded-coaxial structure with a movable
shorting plate, has the distinct features such as thecompactness and the wide frequency-tunability. 1)
Figure 1 shows a schematic layout of the RFQ resonator whose details are described in Ref. 1. A detachable stem shown in Fig. 1 has been introduced
considering the results of the cold test on a half-scale
mode1. 2 ) This stem is used only in high-frequency operations where it is in electric contact with both theconductor tube and the base plate, while it is detachedfrom the base plate in low-frequency operations. It is
expected that the detachable stem reduces the power
consumption because it shares the rf electric current
with the upper stem.

ical simulation into account. 3 ) Misalignment effects on
the beam transmission have been also examined. 4)
Figure 2 shows the measured resonant frequency
along with the values calculated by the MAFIA program. The horizontal axis represents the gap distance
between the top surface of the conductor tube and thebottom surface of the shorting plate. The resonant frequency varies from 17.7 to 39.2 MHz by changing theposition of the shorting plate by a stroke of 790 mm.

~~o~--~--~---~----~

35

~~
\0
'

~ 30

0

Detachable Stem - in

"- °
-- -

_0 _ _ _0 _ __0°...---Meas.
-Calc.

••

20.....--Meas.

15 +-------,r------.----r----,--L-'---- Calc .
o
200
~o
600
800
Distance Tu~ - Short (mm)r--'----='----~/I

MovableShorting
Plate

UPPER PART.6.

---~---.

LOWER PART

Conductor - t - - t Tu~ ~L-~~~~~~

Detachable Stem

Ceramics
PillarPick-up Vertical
Monitor Vane

Fig. 1. Schematic drawing of the RFQ resonator. The
inner volume is about 1700 mm (length) x 700 mm(width) x 1100 mm (height).

Channels for water cooling have been designed basedon the heat analysis. Water for the horizontal vanes
is supplied through the front and rear supports of thevanes. That for the vertical vanes and the rectangulartube is provided through the inside of the upper stem.
The total water flow is 155 £/min at 7 atm. Two turbomolecular pumps (1500 £/s) are fixed on both sides of
the resonator.
The vanes have been three-dimensionally machined
within the accuracy of ±50 11m. The vane parameters
have been determined by taking the results of a numer-

Fig. 2. Measured resonant frequency along with the
MAFIA calculations. The closed circles and the solid
curve represent the measured and the calculated values, respectively, when the detachable stem is out of
the resonator. The open circles and the dashed curve
represent the measured and the calculated values, respectively, when the stem is in the resonator.

Figure 3 shows the measured Q-values and shunt
impedances. The corresponding MAFIA-calculation
curves are shown in the figures as well. The shunt
impedance Rs is defined by V 2 /(2P), where P is therf power consumption and V is the intervane voltage.
As expected, above 30 MHz the measured Q-values andshunt impedances with the detachable stem installed
are larger than those without the detachable stem. The
MAFIA calculations overestimate the measured values
by about 50%. This is considered to result from thefact that the calculation does not realistically treat theroughness of the wall surface and the imperfection of
the electric contact. The power losses estimated fromthe measured shunt impedances are 6 kW at 17.7 MHz
and 26 kW at 39.2 MHz for the designed intervane voltage of 33.6 kV in the cwoperation.
High power tests have been performed with an rf
power source based on an Eimac 4CW50000E, which22112000~~..... • •

10000
8000
6000

"

~°tP

0

4000
2000

o

180
150

Rs (kQ)

120

...••

90
60
30

••

,

~

"

. 0 ,p

0

0
15

20

25

30

35

40

Frequency ( MHz )Fig. 3. Measured Q-values and the shunt impedancesalong with the MAFIA calculations. The data of symbols and curves are obtained under the same conditions
as in Fig. 2.

has a cw power of 40 kW at maximum between 16.9
MHz and 40 MHz. Following results have been obtained: (1) The RFQ can be stably operated in the cw
mode when the intervane voltage is between 15 kV and
30 kV. The vacuum stays in a range of 1 - 3 X 10- 7
Torr at the pump head. No temperature rise has been
detected during the operation. (2) Emissions of bluewhite glow are observed on the ceramic pillars when
the intervane voltage is below 10 kV. This is considered to be caused by the multipactoring phenomena.
(3) Emissions of red-white light are observed above theintervane voltage of 35 kV , which is due to the heatcaused by the dielectric losses in the pillars.

222

In order to eliminate the drawbacks (2) and (3) described above, the shape of the pillars has been reexamined by use of the MAFIA code. Two different types of pillars, which have a smaller electric fieldwithin themselves , have been fabricated and will betested soon.
Acceleration tests have been done using beams froman 18GHz-ECRIS.5) The beam line from the ECRIS
to the RFQ is described in Ref. 6. The velocity of theaccelerated beams has been measured by means of the
TOF method , using three capacitive pick-up probes
settled in a diagnostic box which is located just after
the RFQ .
The accelerated ions so far are Ar 3 +, Ar 6 +, Ar 11 +,and 0 5 + at the frequencies of 17.7, 26.1 , 34.4, and 39.2
MHz , respectively, and at the intervane voltage around
20 kV. The maximum transmission efficiency obtained
from the first test was 85% with the beam intensity of
10- 50 ep,A. The velocity of the accelerated beam is inagreement with the designed value within 1%.
Measurements of the beam emittance and the acceleration tests with full-intensity beams from the ECRIS
are in preparation.
References
1) O . Kamigaito et al.: Jpn. J. Appl. Phys., 33, L537
(1994).
2) O. Kamigaito et al.: ibid. , 34, 5799 (1995).
3) Y. Batygin et al. : RIKEN A ccel. Progr. Rep., 28 , p. 172(1995).
4) Y. Batygin et al.: This report, p. 223.
5) T. Nakagawa et al.: This report , p. 220.
6) N. Inabe et al.: RIKEN Accel. Progr. R ep. , 28, p. 166(1995).

RIKEN Accel. Prog. Rep. 29 (1996)

Misalignment Effect of Vanes on Beam Transmission Efficiency
in an RFQ Linac
Y. Batygin, A. Goto, O. Kamigaito, and Y. Yano
Beam transmission efficiency in an RFQ linac is affected by several reasons. Our previous study!) indicated significant sensitivity of beam dynamics on small
systematic deviations of RFQ cell parameters from theoriginal design. In this paper the effect of random vaneerrors on the beam transmission efficiency is examined
to define the engineering tolerance for RFQ vane machining and alignment .
Random errors in manufacturing RFQ vane tips
result in the amplitude growth of transverse andlongitudinal oscillations. Analytical treatment 2 ) showsmonotonous enlargement of transverse oscillation
amplitude r max and vertical size of separatrix(~g) = (~P) /v s after passing through the RFQ section with N cells:(lirm=? = 2N [(8ro )2 + r;;'=l((8~/ +4(Ii~ )2
)

(1)

100

(a)

-100

-2 ~--~----r---~--~----~--~
1IiO

25

50

Z.C M

75

100

z. ell

125

150

100

::;;:

(b)

u
X

0

-100

-2~---r--~r----r--~----~--~
25

50

75

100

25

125

50

75

100

125

100

125

150

Z.C M

Z,CM

100

~

~

(c) :

~p.,

'><'

-100

z. cv:

25

50

76
Z. cv:

Fig. 1. Phase trajectories (left) and x-trajectories (right) of particles in the RFQ structure with various
values of error in the vane fabrication: (a) 0 microns; (b) ±50 microns; (c) ±100 microns.

223

where a(z) is the vane-tip profile of the modulated electrodes defined by equation:

X

[a~)

r

+ A1o[ka(z)] sin(kz) = 1.

(6)

From boundary conditions (4), (5) the expression for
RFQ potential with a dipole component is given by:where 8ro is an axis displacement, 8Ro an error in average radius of the structure Ro = a/ VX, 8L an error
in cell length, 8U an intervane voltage instability, n f alongitudinal oscillation frequency, w an RF frequency,
W a particle energy, A an acceleration efficiency, r.p a
synchronous phase.
To obtain accurate estimation of this effect on the
beam transmission efficiency, the computer simulation
using code BEAMPATH3) was done. The following
parameters were randomly distributed at every cellwithin the maximum error ±8: cell lengths L i , aperture
radius ai, maximum distance from axis to electrodesmai, and axis displacement 8roi' Results of simulation
are presented in Table 1 and Fig. 1. Random errors in
the RFQ geometry induce particle losses both in longitudinal and transverse directions. From the resultsof simulations it follows that the error of 50 microns
does not create any serious degradation of the beam
parameters while an error of 100 microns could cause
notable decreasing of beam transmission efficiency.

U(r,B,z) = -

~o [X

Gf

cos 20+ AIo(kr)sin(kz)]+ U o [x + a(z)l~
2
a

2

[x+ ~

(ka)2 Sin(kz)]. (7)4The dipole component decreases the focusing strengthof a pure RFQ field if the electrode is shifted outside
the channel ~ > 0 (and vice versa if ~ < 0):
x
U ~ [
A
2· (
)]
Edipole= -2 a2 X + "4 (ka) sm kz .
o

(8)

The dipole component results in shifting of a stable oscillation point from the axis . From equation(7) the new stability point Ex (xo) = 0 is defined as
Xo = ~/2 . Beam dynamics calculation performed forthe electrode displacement of ~ = 50 microns showsthat the center mass of the beam oscillates around the
new stability point Xo = 25 microns (see Fig. 2). In
this case no significant changes of beam parameters
were observed. Finally the engineering tolerance of 50
microns was thus adopted for the vane tips fabrication.

Table 1. Change of beam transmission efficiency due toerrors in the vane fabrication.
0.006

l.
2.
3.

8, microns
0
50
100

1=0
0.94
0.92
0.80

1=1 rnA
0.87
0.85
0.70

0 .0040.002~

Another possible source of particle losses is a disturbance of pure RFQ quadrupole symmetry due to a
dipole field component. This effect was studied for thecase when one of the RFQ electrodes is shifted fromits ideal position at the distance~ . It results in appearance of extra terms proportional to cos (), cos 2(),
cos 3() ,... in the RFQ potential expansion. The newlowest order RFQ potential is given by:U(r, B, z) = - ~o[X(~f cos 2B + A1o(kr) sin(kz)+ AOI ~ cos () + All II (kr) cos () sin(kz) ] . (3)Coefficients A 01 , All are defined by new boundary conditions where potential is kept constant at the surfaceof electrodes U(r,(), z) = - U o/2:
U(x,y, z) = -U o/2

x = -a(z) ,(4)

U(x,y,z) = -U o/2

x = a (z) + ~ ,

(5)

224

0

x

0.000

·0002

·0004

-0.006 0

25

50

75
Z. CM

100

125

150

Fig. 2. Oscillation of the center mass of the beam due tovanes asymmetry of ~ = 50 microns.

References
1) Y. Batygin, A. Goto, O. Kamigaito, Y. Yano: Proc.
10th Symp. on Accel. Science and Technology, Hitachinaka, p. 359 (1995).
Preprint 1HEP 72-29, 72-30,
2) 1. M. Kapchinsky:
Protvino (1972), in Russian.
3) Y. Batygin: Proc. 3rd European Particle Accelerator,
Berlin, Germany, p. 822 (1992).

RIKEN Accel. Prog. Rep. 29 (1996)

Design Study of Siberian Snake Magnet for RHIC-Spin Project
M. Okamura, T. Kawaguchi, K. Hat an aka , H. Sato, Takeshi Toyama, and T. Katayama
In Relativistic Heavy ion Collider (RHIC) Spin
Project,l) it is intensively required to accelerate a proton beam to 250 Ge V with high polarization. A device
called Siberian Snake can overcome the depolarization
spin resonance that occurs in a synchrotron. A design
study of Siberian Snakes has been done at Brookhaven
National Laboratory (BNL). In parallel with them, we
also began to study about it.
A Siberian Snake is a kind of Spin rotators and therole of it is to rotate the spin by 180 0 precisely without
any orbit displacement and any deflection. By inserting two Siberian Snakes on opposite sides of each of two
RHIC rings, the depolarization from imperfection andintrinsic depolarizing resonance can be avoided up to
the top energy of 250 Ge V. The Snake magnet adopted
for RHIC consists of four helical dipole magnets using
superconductors twisted by 360 0 • This type of Snakes
can rotate spin with smaller orbit excursion. In addition to the Siberian Snakes, spin rotators are required
to be used at the intersection point where PHENIX is
installed. To simplify the construction of spin rotators,
the same structure as Snake magnets was adopted.
Two methods have already been suggested for winding of cables for actual magnets. The first method has
been developed by Magnets Division at BNL. The cable is wound up along grooves on the cylinder. The
other called "Direct Wire Technology" has been developed at SSC. In both methods, thin cables (¢ = 1 mm)comprise coils to reduce the heat leak through power
feeds. However it is difficult to fix such thin cables so
as not to cause quench. So, we have proposed to use
Rutherford cables by considering their thickness withwhich the heat leak does not exceed the capacity of
the cryogenic system, and have begun to design new
Snake magnets.
To begin with, we calculated magnetic fields forthe helical magnet designed at BNL. Two dimensional(2D) analysis was at first made because of complexityof the shape of magnet . However, it was difficult to estimate the fringe field and longitudinal component of
the field using the 2D calculation. Then we calculated
the three dimensional (3D) magnetic field using thecomputer code TaSCA. Figure 1 shows a total viewof the helical dipole magnet. The coil consists of an inner layer and an outer layer. The inner and outer radiiof the two-layer coil and the length of helical section
are 50, 80, and 2200 mm, respectively. The inner andouter radii and the length of yoke used for the calcu-

lation are 90 , 175 and 2200 mm, respectively. The results of 3D analysis for the magnetic fields at the centerof the magnet are shown at Table 1. The magnetic fieldstrength is 4 T. However, the longitudinal componentof the magnetic field at the place 3 cm apart from thebeam axis is more than 8% of the dipole field component. Uniformity of the dipole component is about 1%.
It is necessary to optimize the coil geometry, in orderto reduce the longitudinal component and get better
uniformity of the dipole component.

.A(60.0, 3'~oO, 3'~00, 3·~ 0. o
' 3·~0.0.A(40.0'32,°.0' 3~o.o-36,°.0' 38,°°.A(·40.0.A(·60.0

Fig. 1. A total view of the helical dipole magnet.

Table 1. Magnetic fields at the center of the magnet.

Field strength on axis
T
Field strength of longitudinalcomponent at r=30 mm
T
Field uniformity of dipole
component at r= 30 mm%
Current density
A/cm 2

without yoke with yoke
2.83
3.98
0.246

0.343

1.13
21000

1.05
21000

We will analyze the beam orbit and spin motion ofpolarized protons in Siberian Snakes using the resultsof 3D calculation. The result of this research will bereflected to the design of our new Snake magnets with
Rutherford cables.
The authors are grateful to Hitachi Co., Mitsubishi
Electric Co. and Kyokuto Boeki Kaisha Co . for theircollaboration.
References
1) H. En 'yo et al. : This report , p. 80.

225

RIKEN Accel. Prog. Rep. 29 (1996)

Progress of RIKEN RI Beam Factory Project
Y. Yano , A. Goto, and T. Katayama
The factory utilizes the "projectile fragmentation"
to generate RI beams of intermediate energies. To enable the efficient generation are needed high-intensity
primary heavy-ions , up to uranium ions, with the energies exceeding 100 MeV/nucleon. Such heavy-ions will
be provided by a K2500-Me V superconducting ring cyclotron (SRC) which will be built for an energy boosterof the existing K540-MeV ring cyclotron (RRC). RI

The "RIKEN RI Beam Factory" is aimed at providing RI (Radioactive Isotope) beams over the wholeatomic-mass range with the world-highest level of intensity in a wide energy range up to several hundreds
MeV /nucleon. A very preliminary plan of the factory
is illustrated in Fig. 1. The existing facility will be expanded to the adjacent site where a two-story building
will be constructed underground.

ECRIS-18

10

20

30

40

50 M

'DSR

B2F

B2F

B1F

Fig. 1. Preliminary layout of the RIKEN RI Beam Factory. The SRC and the MUSES are housed in a
two-story building underground. Experimental setups are not depicted.

beams will be generated by the Big RIPS. A new typeof experimental installation called "MUSES" (M ultiUSe Experimental Storage rings) will also be constructed. It consists of an accumulator cooler ring(ACR), a booster synchrotron ring (BSR) and double storage rings (DSR). With MUSES, various typesof unique colliding experiments will become possible:
ion-ion merging or head-on collisions; collisions of either electrons or X-rays with ion (stable isotope or RI)
beams; internal target experiments; and atomic andmolecular physics with cooler electron beams.
In 1995 fiscal year, the budget for the three-year
R&D to design the details of the factory has been partially approved. This budget is to be invested to fabricate a test model of the SRC sector magnet.
Here we describe the revised parameters of thevariable-frequency linacs-cyclotrons system which possesses such acceleration performance that a 100MeV /nucleon uranium beam with the intensity over226

1 pp,A is obtainable. On the other hand the revised
parameters of MUSES are described by Katayama etal.l) The design study of each accelerator component
is given in separate papers in this progress report.
RILAC serves as the initial-stage accelerator. We
use t he acceleration radio-frequencies between 18 and
38 MHz because this linac works stably in this frequency range. In order to upgrade the RILAC performance in the beam intensity by one or two orders ofmagnitude, its new pre-injector system consisting of afrequency-tunable folded-coaxial RFQ linac (FC-RFQ)
equipped with an 18-GHz ECR ion source (ECRIS18) has been developed. 2 ) In the recent test of thissystem, as for FC-RFQ, the variability of the resonant frequency was measured to cover from 17.7 to39.2 MHz. In addition the beam transmission efficiency of 85% at the maximum was obtained .3 ) Thisefficiency agrees well with the value calculated by thecomputer code BEAMPATH.4 ) High-intensity highly-charged ion beams have been obtained by ECRIS-18.
Some results are given in the report on this source. 5 )The pre-injector is scheduled to be installed in due site
in the summer of 1996. It will be used jointly with theexisting 450-kV Cockcroft-Walton accelerator.
The pre-accelerated beam is fully accepted and accelerated by RILAC.
A charge-state multiplier (CSM) consists of an accelerator, a charge stripper and a decelerator . Its
functions are to produce higher charge states of ion
beams by further increasing the stripping energy andto reduce their magnetic rigidity by decelerating themto the initial energy. With this device the magnetic
rigidity of a most-probable charge-state beam can be
reduced to the acceptable value of RRC even when
the injection velocity into RRC is increased. The accelerator and decelerator are of a type of frequencytunable IH linacs, whose operational radio-frequencies
are twice as that of RILAC to double an acceleration
gradient. Maximum gap voltages are set to be 350 kV
for 62 cells of the accelerator and for 28 cells in the decelerator, and total lengths of each are 12.4 m and 5.5
m , respectively. Transmission efficiency through CSM
depends only on charge state distributions behind thecharge stripper foil. We estimate the yield of a given
charge state in terms of Shima's formula. 6 ) A preliminary design of CSM is given in the report by Tomizawa
et al. 7)
For the present , we set the maximum beam energyof SRC to be 400 MeV /nudeon and this energy to beachieved at 38 MHz of the maximum rf frequency of
RILAC. Consequently a velocity of RRC output beam
is to be amplified by a factor of 2.26 by SRC. To thisend, the mean extraction radius of SRC is taken to be
2.26 times the mean injection radius. We set this mean
injection radius to be 2/3 times the mean extraction
radius of RRC; accordingly mean injection and extraction radii of SRC are 2.37 m and 5.36 m, respectively.
Then, to meet a good matching condition, the harmonic number in SRC becomes 6 as that in RRC is 9.
The radio-frequency range of SRC is from 18 MHz to
38 MHz, which is the same as that of RRC .
The 6-sector SRC with the sector angle of 25 degrees
has been investigated. The design details are describedin the reports by Mitsumoto et al. 8) and by Kawaguchi
et al. 9 ) The maximum field strength in the extraction
region of SRC becomes 4.1 tesla.
We estimate the beam intensity expected to obtainfrom SRC for some typical gaseous elements and uranium ions, on the basis of the following assumptions:(1) the transmission efficiency through FC-RFQ is 85%
irrespective of kinds of ion beams; and (2) from theexit of FC-RFQ to the extraction beam line of SRC,
the beam loss occurs only in the stripping process, i.e.
this means that the transmission efficiency of both of
RRC and SRC is 100% (this can be achieved by theoff-centering acceleration technique which is routinely
used for RRC). In Table 1 is given comparison of the
ECR beam intensity (IECR) of a given charge state(qECR) required to obtain an ion beam of the energy(E SRC ) with the intensity (I SRC ) to the present performance of ECRIS-18 and 14.5 GHz CAPRICE. 10) Quite
high beam intensity is expected to be provided especially for light ions , but use of such primary beams
is not realistic from a viewpoint of the radiationshielding-problem. We consider that primary-beam intensity of 1 pf-LA is sufficient to generate RI beams withdesirable intensity in the whole mass region: These
primary beams will give us a possibility to create andidentify as many as one thousand kinds of new isotopes. High current beams are used with a low duty
factor of nearly 0.01 % for MUSES.
Table 1. Comparison of the required beam intensity tothe performance of the ECRIS-18 and the 14.5 GHz
CAPRICE.
E SRC

Ion

ISRC qECR IECR

MeV lu pi-LA

el-L A

IECRIS18

ICAPRICE14.5

el-LA

el-L A

extrac. voltage extrac. voltage
16 0 816 0 740 Ar17
8 4 Kr 3O
129Xe 38
238U85
238U58
238U49400 100
400 100
330 20300 2
200
200 0.02
150 0.2
100

6
7
7
8
14
15
28
22
16

700
820(1)
410
470
120
100
16(2)
75(3)
110

10 kV 15 kV
550 610
110
330
90

410
110

20 kV
800
100
500
120
80
20
25(*)

(*): CAPRICE 10 GHz(1): without stri pper 1. (2) with stripper 2 (yield is estimated to be30%). (3) yield for 58+ is 7% while that for 55+ (most probable) is
15%.

References
1) T . Katayama et al.: This report , p. 238 and 240.
2) A. Goto et al.: This report, p. 219.
3) O. Kamigaito et al.: T his report , p . 221.
4) Y. Batygin et al.: This report, p. 223.
5) T. Nakagawa et al.: This report, p. 220.
6) K. Shima et al.: Atomic Data and Nuclear Data Tables,
51, 174 (1992).
7) M. Tomizawa et al.: This report, p. 228.
8) T. Mitsumoto et al.: This report, p. 230 .
9) T . Kawaguchi et al.: This report , p. 232.
10) Y. Kanai et al.: This report , p. 208.

227

RIKEN Accel. Prog. Rep. 29 (1996)

Conceptual Design of a Frequency-Tunable IH Linac
M. Tomizawa
In the proposed "RIKEN RI Beam Factory", thebeam of the whole mass ranges up to uranium is accelerated up to several hundreds MeV/nucleon. To
inject a heavy ion such as uranium into the RRC, it
is necessary to increase the charge state of the beamfrom the RILAC. A charge-state multiplier (CSM) is
proposed to increase the charge state of the heavy ion
beam with unchanged velocity. 1) The CSM consists ofa linear accelerator, a charge stripper and a decelerator. For example, 238U19+ beam is accelerated from
1.3 to 2.4 MeV/nucleon, charge-stripped to 41+ by
the carbon foil, and decelerated to 1.3 MeV/nucleon
by the decelerator. An interdigital H mode (IH) cavity is suitable for these linacs, because the IH cavity
has a high acceleration gradient in the present velocity range. The frequency range is set to 36- 76 MHz,
which is twice as that of the RILAC to get a high accelerating gradient and to reduce the cavity size. The
required mass to charge ratio is 7 to 28.
The designed CSM consists of three accelerator
tanks and a decelerator tank. The main parametersof the tanks are shown in Table 1. Quadrupole triplets
are placed between the tanks to focus the beam. In
order to get a stable longitudinal beam motion, synchronous phases are set to -25 and 25 deg. in the accelerators and the decelerator, respectively. This acceleration scheme has been used in the IH linac toaccelerate unstable nuclei at INS. 2 ) The length between tanks is chosen to be about 85 cm in which
the quadrupole triplet is installed. The required fieldstrength is less than 40 T /m at a bore radius of 2
cm. The multi-particle tracking on three dimensional
phase space was performed. The effects due to thefoil were neglected in this calculation except for thechange of the charge state. Maximum longitudinal andtransverse emittances at 100% transmission are 6007T
keV /nucleon·deg. (f = 51 MHz) and 1.67T mm'mrad(normalized), respectively. These are larger enoughthan those of the actual beam from the RILAC.

lated result was compared with the measured data of
the IH linac (tank-4) constructed at INS. As a result,the MAFIA predicted a resonant frequency about 9%
higher than measured one. The predicted resonant frequency increases with the mesh number. The shunt
impedance and the gap voltage distribution are well
reproduced by the calculation.
The schematic drawing of the frequency tunable IH
cavity is shown in Fig. 1. In the present design, thecavity has a rectangular shape. The upper stems areconnected on the wall directly, and the lower stems
are put on the ridge. The frequency is tuned by moving a shorting plate in contact with the ridge and thewall. For impedance matching, the cell and end inductances are changed at the same time by this shorting
plate. As a result, flat field distribution is obtainedin the whole frequency range. The fine adjustment of
the field distribution is performed by some capacitive
tuners facing the ridge surfaces. Table 2 shows thecalculated rf parameters of the decelerator cavity. The
frequency is changed from 31 to 69 MHz by the 1.2 m
stroke of the shorting plate. The shunt impedances arearound 170 MO/m. It is not sensitive to the resonant
frequency. The power consumption in the cavity is lessthan 65 k W. The rf current on the sliding contact between the ridge and the shorting plate is 63 A/cm(rms)at maximum. In such a high current density, the rf
contact between the short plate and the ridge must
be examined carefully. One of the candidates is thesliding contact using silver-graphite spheres supported
by a flat spring via a thermal insulator. 3) In the

1m

Table 1. Main parameters of the frequency tunable IH
linac.
energycell length gap bore rad.
~s(deg.)(m) (cm)(cm)(MeV lu)acc.-l 1.312- 1.657 18 2.98
8.2
-25
1.5
9.1
-2 1.657- 2.003 18
3.31
1.5
-25
-3 2.003-2.390 20
4.03
9.9
-25
1.5
dec.
2.390- 1.313 22
9.2
4.05
2.0
25
tank

The rf characteristic of the IH cavity was analyzed
by the MAFIA code. First, to see the reliability of
the MAFIA calculation for the IH cavity, the calcu228

Fig. 1. Layout of the frequency-tunable IH linac designed
as the decelerator of the CSM.

Table 2. Rf parameters obtained by the MAFIA. In thetable, x shows the distance between the ridge and theshorting plate.
x (m)
0.3
0.8
1.5

f (MHz)
68.6
45.4
31.4

Zs (MW 1m)
169
179
169

P (kW)
64
60
64

J rms (A/em)
63
47
42

cavity using this contact, the rf current of 200 A/cm
has been achieved at 50 MHz.
Figure 2 shows the gap voltage distributions calculated by the MAFIA. Except for the end cells at 68.6
MHz , flat distribution was obtained. The distribution
is quite sensitive to the size of the magnetic flux inducer. Further optimization of the sizes is needed toget better field distribution.

0.5~«S 0.4!:::e••••••••••••••••••

~ 0.3
Q)

000

0>
«S
~ 0.2

Q

•

0000 000000000 00000••••••••••••••••••••••>a.

~ 0 .1

References

o

o

5

10

Cell

15

20

25

Fig. 2. Gap voltage distribution predicted by the MAFIA.

1) Y . Yano et al.: Proc. 10th Symp. on Accelerator Scienceand Technology, Oct. , Hitachinaka, p . 191 (1995).
2) M. Tomizawa et al.: ibid., p. 457.
3) C. Pagani et al.: Proc. 11th ICC , Ionics Pub., Tokyo ,p. 361 (1987).

229

RIKEN Accel. Prog. Rep. 29 (1996)

Design Study of Sector Magnet of the Superconducting
Ring Cyclotron (I)T. Mitsumoto, A. Goto, T. Kawaguchi , Y. Tanaka, T. Kubo, H. Okuno,
T. Tominaka, S. Fujishima, and Y. Yano
The RIKEN Superconducting Ring Cyclotron(SRC) is one of the main accelerators of the "RIKEN
RI Beam Factory." 1) The SRC is expected to boost theenergy of ion beams from the existing RIKEN Ring Cyclotron (RRC) up to 400 MeV/nucleon for light ionslike carbon ions and 150 MeV/nucleon for very heavy
ions like uranium ions. The sector magnets of the
SRC have to be flexible enough to generate isochronous
fields corresponding to a wide rage of energies and forvarious q/ A 's. In this report we describe the featureof the sector magnet together with magnetic field calculation and orbit analysis.
The maximum energies for typical ions are summarized in Table 1. Beam current s are expect ed to b e 100
pf.LA for 400 MeV / nucleon oxygen ions and about 0.2
pf.LA for 150 MeV/nucleon uranium ions . The number of sectors for the SRC has been chosen to be 6,
because in the case of 4 sectors, tune history of ionsfor 400 Me V /nucleon acceleration crosses a resonanceline lJr = 2, which is known as N /2 stop band. Diameter of the SRC is 20 m. The pole length is longer
than 3 m , the sector angle is around 25 deg. , and theweight of one sector magnet is nearly 900 tons. Fromthe mat ching condition with the RRC, the injection
radius of the SRC has been selected to be 2/3 of theextraction radius of the RRC. Main parameters of the
SRC are listed in Table 2.
Table 1. R equired maximum energy of the SRC.
16 0 8 +84 Kr30 +2 38 U80 +400 MeV /nudeon
300 MeV /nudeon

150 MeV /nudeon

Table 2. Main parameters of the SRC.
N umber of sectors
Harmonics
Average radii injection
extraction
RF Frequency

66
2.37 m

5.36 m18- 38 MHz

Isochronous field distributions for typical ions areshown in Fig. 1. The maximum required field in the
sector magnet becomes nearly 4 T in the outer region. Field difference between the injection radius andextraction radius on the sector axis is 0.8 T for 400
MeV/nucleon ions and 0.1 T for energies below 100
MeV /nucleon ions. Therefore the main coil as well as
trim coils for coarse fitting has to be superconducting.
230

1.4
~

'iii
Q)

1.3

!:::
'0

~

1.2

~
c

1.1

u

0>

ctl

E

1.0

Q)

0>

~

Q)

>

0.9

<

0.8

q/A 0.25 58 MeV/nucleon
3

4

5

Average radius (m)Fig. 1. Isochronous field for typical ions.

Magnetic fields and forces were calculated by athree-dimensional code TOSCA.2) For the sector magnet only a quarter part of it was modeled because of
its symmetry. For the coils a complete set of themin only one sector was taken into account in the calculation. Strictly speaking, TOSCA requires all conductors of the system to be taken into account. But
owing to appropriate selection of the reduced potential region, good agreement of the magnetic field on
the median plane can be obtained for both the systemwith six sets of coils placed rotational symmetry andthe system with only one set. This method shortened
the calculation time to be less than 25% of that of thesix-set system.
Equilibrium orbits and betatron tunes were calculated by the computer program that had been originally developed for the RRC. Results of the field distributions by TOSCA were used in the orbit calculations.
Using the four sets of superconducting trim coils,
we expect that the field generated with both the main
coil and the superconducting trim coils can be fitted
to the isochronous field within ±0.01 T for all of theacceleration conditions. Further fine adjustment will
be done with trim coils of room temperature.
Figures 2 and 3 show typical tune values in the casesthat the sector angle is 23 deg. and 25 deg., respectively. In the case of 23 deg. , all tune values are abovelJZ = 1.0. But the maximum magnetic field reaches 4.6
T. In the case of 25 deg. , the tune history for 16 0 8 +ions to 400 MeV/nucleon crosses lJZ = 1.0. The maximum magnetic field , however, is reduced to be 4.1 T.
In Fig. 3 are also shown the tune values for 16 0 7 + ions.
In this case the values are pushed above lJZ = 1.0, but
the beam intensity reduces by a factor of about 2 com-

84Kl<H- 300 MeV/nucleon

1.7
1.6
1.5
N

>-

N

1.4

>-

1.3
1.2
1.1

1.1

238 U8<H- 150 MeV/nucleon

1.0

1.0~~--------k-------~

0 .9

0.9

0.8
1.0

0.8 L----I_...,.-I-,...--......_-'-_.L..--...IL..--""_
1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

Vr

Fig. 2. Typical tune values in the case of 23 deg. sector
angle.

238U80+ 150 MeV/nucleon_'_--'----I

1.8

1.9

Vr

Fig. 3. Typical tune values in the case of 25 deg. sector
angle.

References
pared with that of 16 0 8 + ions. The final selection of
the sector angle will be made after the evaluation ofdifficulty in producing a high field and of risk of crossing the resonance line.

1) Y. Yano et al.: 14th Int . Conf. on Cyclotrons and Their
Applications, Cape Town, South Africa, Oct. (1995) tobe published.
2) Vector Fields Limited, Oxford, England.

231

RIKEN Accel. Prog. Rep. 29 (1996)

Design Study of Sector Magnet the Superconducting
Ring Cyclotron (II)T. Kawaguchi, T. Kubo, T. Mitsumoto, T. Tominaka, S. Fujishima, H. Okuno, Y. Tanaka,
K. Ikegami, A. Goto, and Y. Yano
The superconducting ring cyclotron proposed for the
RIKEN RI beam factory needs six units of superconducting sector magnets, each of which must generate amaximum magnetic field strength of 4 T in the beam
orbital area. We use superconducting coils for the sector magnet to obtain compactness in size and to saveelectric power and cooling water. The yoke and polemade of magnetic soft iron are arranged in the sector
magnet to reduce the ampere turns of the superconducting coils and to minimize the leakage magnetic
flux.
Figure 1 shows an overview of the sector magnet. A
cryostat is not drawn in this figure. The main components of the magnetic elements are superconducting
coils, poles and a yoke. We use two kinds of superconducting coils: a pair of main coils and a group of trim
coils. Both coils are located upper and lower sides withrespect to the mid plane. We have studied two ways ofarrangements for the pole. One is a warm pole systemand the other a cold pole one. Figure 2 shows the both
systems with a cryostat. In the cold pole system, themain superconducting coil is wound around the pole
directly, so the cold mass consists of superconducting
coils, poles and coil vessels. In view of the mechanicalrigidity and magnetic force, we have decided to use thecold pole system. Figure 3 clearly shows the comparison of expanding forces on the straight section of theSUPERCONDUCTING COIL
& COLD POLE
.1CRYOSTAT(VAOJUM VESSEL& 80K SHIELD)
MAIN COIL
COIL VESSEL
10 cm-1-r-COIL
LINK
MID PlANE

BEAM

I- - - - -. -. -_.-.::;J- ------- - -CHAMBERWann pole System

Cold Pole System

Fig. 2. Comparison of pole arrangements.

YOKE

em
600 0
.

1000
~
L4;.

X1200.0

..J -

I
w
0
a:
0
u.

800

600

0

~
z

CI

............ !i ..... .

.--- +. --eot:.DpQt;E--.-..----- --400

SYSTl:M !
~,,-------t.:=---(j --CIz
az 200 +--------------t------",.·-·------ta··---:::----- ::::?--= -;-

k

-<
~

. ~--.7"'.--+---. ------- -····l· - -·

Q.

0
0

2

3

4

5

COIL AMPERE TURNS PER TWO COILS (MAlFig. 1. Overview of superconducting sector magnet (forthree dimensional magnetic field calculation).

232

Fig. 3. Comparison of expanding magnetic forces on coilstraight section.

main coil. The force in the cold pole system can be
reduced to one-third of that in the warm pole system.
This effect is due to the short distance between themain coil and the pole in the cold pole system. However , a serious problem in the cold pole system is thedifference of thermal contraction between the pole andthe coil vessel during the cooldown of the cold massfrom 300 K to 4.5 K. We are currently investigating
this problem.
Figure 4 shows the change of the maximum magnetic
field (at a radius of 6 m on the median plane) and themagnetic forces Fx, Fz in the cold mass (consists ofmain coils and cold poles) , as a function of the ampere
turns of two (a pair of) main coils. The magnetic force
Fz in the vertical direction is supported with two coillinks which are arranged between the upper cold massand lower one.

600

CD

E
~

I.L

/
4 + ........................... .; ........................... + ................ ··········1 · ················· ········ v ···· ··· ·· ...cJ· ······· · · ~ 400

I.L

3 +·_ · ·········t·· ·... ............; .... ~, ...... .~~ ..... ,• . ;. ....

..... -l

C)

300
200

2

.J:. ...

a

...J

w

Ii:

M

~
0
~

w

u

a::

Z

~

N

5 + ....... _...................;.... _................._.... +··..······ .. ··.. _.. ··········i·· .. ·························i···.. ·····,r..:········· -l 500.

. _=_=. . =l..!:. ---_..._....

a

f2
u

./

i=
z

100

w

0

~

Fx
·100

·1

-200

o

1

2

3

4

5

COil AMPERE TURNS PER TWO COilS (MAlFig. 4. Field strength and magnetic forces.

The force of 300 tons maximum causes a mechanicaldeflection of 4 mm maximum of the cold mass. The

magnetic force Fx in the radial direction is generated
with a configuration of the six sector magnets. Eachcold mass is pushed toward outer radius by the forcesfrom sector magnets at both-side. The maximum forceof Fx is estimated to reach about 500 tons per eachmagnet. It is very difficult to support this force bythermal insulating supports which locate in between
the cold mass and the vacuum vessel. To support sucha large Fx, we are investigating a cold ring of 2.6 m
in diameter and 200 mm in thickness which connects
the six cold masses in the central region of the ring
cyclotron.
One of serious problems for a superconducting coil
is coil quench which would be induced with wire movement in the coil under magnetic force. When the coilquench occurs, it is impossible to continue the normal operation, and the coil temperature rises spending
magnetic stored energy, then we need re-cooldown of
the coil. On the other hand, it is very hard to prevent
coil's wire movement, particularly for the non-circularshape coil. Taking account of the above matter, weapply fully cryogenic-stable cooling for both the main
coil and the trim coil adopting a method of conservative liquid-helium bath cooling, for preventing thecoil quench. The operation currents of the main coiland trim coil are roughly set to be 5000 A and 500 A,
respectively. In order to maintain the cryogenic stability, the average current densities of them should beless than 40 A/mm 2 and 50 A/mm 2 , respectively.
The total heat leak of six magnets is roughly estimated to be 500 W at 4.5 K. A helium refrigerator
having a capacity of 1 kW at 4.5 K stage will be used
for six sector magnets and for the beam injection andextraction channels. An electric input power for the
refrigerator will be 500 to 1000 kW. Weight of the total cold mass of six magnets is about 360 tons, and it
will take almost one month for the cooldown of the coldmass from room temperature to 4.5 K by the helium
refrigerator.

233

RIKEN Accel. Prog. Rep. 29 (1996)

Design Study of the Injection System of the Superconducting
Ring Cyclotron (III)H. Okuno, T. Tominaka, T. Kubo, T. Mitsumoto, T. Kawaguchi, Y. Tanaka,
S. Fujishima, K. Ikegami, A. Goto, and Y. Yano
In the RI beam factory project,l) the Superconducting Ring Cyclotron (SRC)2) is designed to boost theenergy of the ion beams from the existing RIKEN Ring
Cyclotron (RRC) up to 400 MeV lu for light ions suchas carbon and 150 MeV lu for very heavy ions such asuranium. In this report , we describe the status of thedesign study of the injection system for the SRC.
Figure 1 shows one of injection trajectories now under consideration. The beam is injected through oneof the valleys into the central region of the SRC and isradially guided to the 1st equilibrium orbit. The transport system consists of three bending magnets (BMl,BM2, BM3), two magnetic inflection channels (MIC1,
MIC2) and an electrostatic inflection channel (EIC).
The injection energies required to get the maximum
output energies for threee kinds of beams are shown in
Table 1.

valley region and the beam trajectory there changes
largely depending on the kind of acceleration condition. The bending angle in the valley region is estimated to be about 50 degrees at the maximum. Figure 2 shows an example of the difference of beam trajectories in the valley region between U and Kr ions.

o

-2

-4

-6

x [m]
Fig. 2. Examples of beam trajectories in the valley region.
The upper curve is a trajectory for U (150 MeV lu)
acceleration and the lower is one for Kr (300 MeV lu).

Fig. 1. The schematic layout of the SRC and an example
of an injection trajectory.

Table 1. The energies of injected beams required
for the maximum energy acceleration.
Charge
16

0
84Kr
238U

8+
30+
80+

Einj
(MeV lu)
50.4
41.7
24.5

Table 2. Characteristics of the injection elements.

Eext(MeV lu)
400
300
150

This radial injection method is most straightforward
and is adopted widely in many ring cyclotrons. However, it is more difficult to apply the radial injection to
the SRC than to the normal conducting ring cyclotron,
because there exists strong negative fringe field in the234

The MICs are inserted between the poles of the sector magnets to increase the bending power of the sector
field locally. The EIC is placed in the position where
the injection trajectory is matched finally with the 1st
equilibrium orbit. Characteristics of the injection elements are summarized in Table 2. The three bending magnets and MIC1 require to use superconducting.coils to achieve the required fields. The sizes of theelements must be small enough so that they can be(1) Bending magnets
Element() (deg)
BMI
39.4
BM2
52.5
BM3
100.6
(2) Inflection channels
Element() (deg)
EIC
MICI
MIC2

11.96
88.35
88.46

p (cm)

B (T)

80.0
85.0
63.5

4.55
3.40
3.61

p (cm)

383.9 - 623.6
57.5
63.5

b..B or b..E
(T or kV Icm)
81.2
0.90
0.33

placed within the limited available space in the SRC
central region.

He Channel

Conpensation Coil
Main Coi

Figure 3 shows a cross-section of the MIC! designed.
The MIC! contains a main coil and a compensationcoil. This two-coil system provides the required field
profile with an induction level up to 0.9 T in the boreof the inflection channel and with a small magnetic
field disturbance in the acceleration region. The coils
are indirectly cooled by 4.2 K liquid helium via thecoil housing. The beam bore is also cooled by water inorder to prevent the coils from quenching due to thebeam losses. Required current densities for the coils
are as high as about 300 Ajmm2 . Analysis for themechanical and cryogenic stability is in progress.
References
1) Y. Yano et al.: Int. Conf. on Cyclotrons and Their Applications, Cape Town, South Africa, 1995, in press.
2) T. Mitsumoto et al.: This report, p. 230.

Fig. 3. A cross-section of the MICl.

235

RIKEN Accel. Prog. Rep. 29 (1996)

Design of a Model Sector Magnet of the Superconducting
Ring Cyclotron
T. Kubo, T. Kawaguchi, T. Mitsumoto, T. Tominaka, S. Fujishima, H. Okuno, J.-W. Kim,
Y . Tanaka, K. Ikegami, A. Goto, and Y. Yano
An RI-beam factory based on the projectile fragmentation method has been proposed as an extensionof RlKEN Ring Cyclotron (RRC).l) It is planned inthis project to build a superconducting ring cyclotron(SRC) as a post accelerator of RRC. The SRC consists of six identical superconducting sector magnets
whose sector angle is 25 degrees and maximum magnetic field is 4.1 T. The mean injection and extraction
radii of SRC are 2.37 m and 5.36 m, respectively. The
maximum energies are: e.g. 400 MeV/nucleon for lightheavy ions like carbon, 300 MeV/nucleon for krypton
ions, and 150 MeV/nucleon for uranium ions. Design
studies of SRC are reported in this progress report. 2 ,3)Here we report on a design of a model magnet of thesuper conducting sector magnets.
We plan to build a full-scale model so that the design of the sector magnet can be made sure under thecondition as close to the real one as possible. This isparticularly important to see if the huge magnetic force
due to the high magnetic field and current density 3)
can be properly supported. We aim at generating amagnetic field higher than 4.1 T that is required in
the current design of SRC.
Figures 1 (a) and (b) show a schematic drawing of
the model magnet. The cold-pole method has been
adopted as described in Ref. 3. The pole pieces are
separated from an iron yoke and cooled down together
with main coils in a cryostat. The coil vessel that
accommodates the main coil is attached to the sideof the pole piece. The upper and lower pole pieces
are linked each other. Such an arrangement allows
the pole pieces to support the magnetic force exerted
on the main coils. Furthermore it enables to reducethe magnetic force expanding the main coil, since themain coil can be placed very close to the pole. 3 ) Several
support links are shown in Fig. 1; the horizontal ones
support the shifting force and the vertical ones theweight of pole pieces and main coils. The cold-mass
weight and the total magnet weight are estimated to
be about 60 and 1000 tons, respectively.
We plan to use a cryogenically-stabilized superconductor in order to prevent the main coil fromquenching. 3 ) The cooling is made by the liquid-helium
bath-cooling method. The conductor to be used has across-sectional size of 7.5 mm x 14 mm and consistsof a Rutherford-type NbTi cable and a stabilizer housing. The stabilizer material will be either copper oraluminum. The conductor is designed to be stable up
to 6000 A when the magnetic field applied is 6 T andthe cooling efficiency is assumed to be 50%. However

236

a)
9700
8450
YOKE ':1'-

8DK SHI E LO:!:,

SUPPORT
LINK

01
o

(\)
(ll

--r--

I

b)
\
\

POL E LI NKr

COIL

TRIM COI L--~-.-------, --.:---~~~~~~I

5160

Fig. 1. A schematic drawing of the model sector magnet:(a) a side view ; (b) a top view.

we plan to excite the main coil with currents lower
than 5000 A, because the detorioration of cooling may
happen in some parts of the coil. The current density
at 5000 A is estimated to be about 40 A/mm 2 , taking
account of conductor gaps for the liquid helium andthe insulation. The maximum stable current will bechecked in the test operation of model magnet . The
number of turns is taken to be 1200 so that the maximum ampere-turn can be 6 MA.
Figure 2 shows median-plane field distributions
along the central line of sector which were calculated by
the code TOSCA.4) The solid line in the figure shows
the distribution when the ampere-turn is 6 MA. The
field is found to be around 5 T, which is well above
the value required for SRC . The maximum field in themain coil is calculated to be 6.35 T, which is smaller
than the stabilization limit at 5000 A. The stored energy is calculated to be 151 MJ.
Only the cold mass and cryostat will be first made

5.0
4.0

E
'0

Q)

3.0

;;::

u

'a;
c:

2.0

OJ

co
:::2

1.0

-1.0
100

200

300

400

500

600

700

Radius (em)Fig. 2. Calculated median-plane field distributions along
the central line of sector. The horizontal axis denotedas Radius gives the distance from the center of sector.
The ampere-turn is taken to be 6 MA. The solid anddotted lines show the distributions with and without
the iron yoke, respectively.
because of the limitation of budget and accommodation space. The iron yoke will be added later. We plan
to operate the model magnet without- the yoke for awhile. The dotted line in Fig. 2 shows the field distribution at 6 MA in the absence of the yoke. In thiscase the median-plane field is reduced by 20 to 30%.
However the field strength in the main coil does notdecrease that much. The decrese rate is calculated tobe 5 to 10%. So the operation without the yoke would
give us useful information.
The total heat load has been estimated to be about
140 W at 4.5 K. A liquid-helium refrigerator with acapacity of about 200 W at 4.5 K will be purchased.
We plan to test a prototype of superconducting trim
coil by installing it onto the pole surface as shown in
Fig. 1. The cryogenically-stable cooling will also be
applied to the trim coil. We also plan to install andtest a prototype of superconducting magnetic channel
which will be used for the beam injection or extraction.

References
1) Y. Yano et al.: Int. Conf. on Cyclotrons and their Applications, Cape Town, South Africa, 1995, in press.
2) T. Mitsumoto et al.: This report, p. 230.
3) T. Kawaguchi et al.: This report, p. 232.
4) Vector Fields Limited, Oxford, England.

237

RIKEN Accel. Prog. Rep. 29 (1996)

Double Storage Rings for MUSES
T. Katayama, Y. Batygin, N. Inabe, K. Ohtomo, T. Ookawa, M. Takanaka, M. Wakasugi,
S. Watanabe, Y. Yano, K. Yoshida, J. Xia, Y. Rao, and Y. Yuan
is installed downstream from the Big RIPS (Fig. 1).
The DSR permits various types of unique colliding experiments; ion-ion merging or head-on collisions; collisions of electron and ion (stable or RI) beams; internal
target experiments; and atomic and molecular physics

A new type of experimental facility, MUSES (MultiUSe Experimental Storage rings) , is proposed for
RIKEN RI beam factory. It consists of an Accumulator Cooler Ring (ACR), a Booster Synchrotron Ring
(BSR) and Double Storage Rings (DSR). This MUSESECRIS-18

o

10

20

30

40

501.4

::;;
o

It)

.

o

FCRFO@ ·

/0::/

o

M

RILAC t
f

B2F

B2F

B1F

Fig. 1. Preliminary layout of the MUSES. The accelerators are housed in the 2-story building.

with cooler electron beams. On the other hand, theACR functions exclusively for the accumulation andcooling of RI beams and the BSR works solely for theacceleration of ion and electron beams.
The DSR consists of vertically stacked two rings of thesame specifications as shown in Table 1. Each lattice
structure takes the form of a racetrack to accommodate
two long straight sections. These straight sections of
one ring vertically intersect those of the other ring at
two colliding points. The ring circumference is 258.732
m, which is 46/6 times the extraction circumferenceof the Superconducting Ring Cyclotron (SRC), 5.363
m. It means that the harmonic number of DSR is
46 while that of SRC is 6. The maximum Bp-value
becomes 14.6 Tm when the dipole field strength is 1.5
T at the maximum. The maximum energy is then, forexample, 3.5 GeV for protons; 1.4 GeV /nucleon forlight ions of q/ A = 0.5; and 1.0 GeV /nucleon for U92 +ions. For electrons the BSR boosts them up to the
maximum energy of 2.5 GeV from 300 MeV injector
linac, and they are stored in the DSR. In the present
lattice structure, the betatron tune values are 18.130

238

Table 1. Parameters of the DSR.
Circumference C (m)Max. Bp (Tm)
Average radius R (m)Max. beam energy (GeV /u)protonion (q/ A = 0.5)
(q/ A = 0.387)(q/ A = 0.333)
Betatron tune value (Qx/Qy)

258.732
14.60
41.20
3.50
1.33
1.00
0.80

18.130/10.197
Mometum compaction
0.00171
Transition,
24.20
Max. betatron amplitude ((3x/ (3Yl m)
22.0/17.9
Max. dispersion function (Dx/ D Y1 m)
0.537/0.697
Betatron amplitude at Interaction
0.600/0.600
point ((3x * /(3/, m)Length of field-free section
at colliding section (m)5.016
Natural chromaticity (Q~/Q~)-45.59/-30.94

(horizontal) and 10.197 (vertical). The operating ionbeam energy is kept to be under the transition energy,
since the transition gamma is as high as 24.20. At thecolliding points the beta-function amplitudes are 0.6 m
for both directions. The field-free section near the colliding points where experimental detector systems are
installed , is 5.0 m in length. These two long straightsections are dispersion-free in horizontal and verticaldirections.
One of the key researches planned at the DSR isthe colliding experiment of an electron beam with an
RI beam: 2.5 GeV electrons accumulated in one ringof the DSR collide with an RI beam stored in theother ring. The scientific aim of this experiment is todetermine the charge and current distribution in theneutron- or proton-rich radio-active nuclei. To keep a
Table 2. Parameters of the stored electron beam.
Max. stored beam energy Ernax (GeV)
2.5
Max. stored beam current I (A)
0.5
Max. stored o. of electrons N
2.7 x 10 12
Injection energy Ei (GeV)
2.5
Beam emittance at 2.5 GeV (e xley) (nm:rad)8 .5 /25.5
Energy spread !::l.E I E
6.8 X 10- 4
Bunch length (j (em)0.50
RF voltage VRF (MV)
2.0
Revolution frequency Jrev (MHz)1.159
RF frequency JRF (MHz)498 .2Harmonic No. h430
23
N umber of bunch (typical)
Touschek lifetime at 2.5 GeV (s)4.55 x 10 4
Synchrotron radiation loss
at 2.5 GeV (keV Iturn)371.7

sufficiently long Touchek lifetime, the RF voltage of 2.0
MV is applied to the electron beam. The detailed specifications of stored electron beams in the DSR are given
in Table 2. The number of stored electrons amounts up
to 2.7 X 10 12 particles, which is limited due to the longitudinal coupled bunch instability. The typical colliding
luminosity for the electrons and RI ions is estimatedto be 5.6 x 10 26 cm 2/s, provided that 1 x 10 7 particles
of RI ions are stored and synchronously collide withelectron bunches'!) In order to further improve the luminosity, the installation of a powerful pulsed heavyion source, e.g. a laser ion source or a metal-vapor ion
source, should be considered.
Another envisaged experiment is the isotope shift of
X-ray absorption by the Li-like or H-like unstable nuclei. To produce the short wavelength X-ray of 20-1000
eV energy, an undulator will be inserted in an electron
ring.2) To obtain the high flux mono-energetic X-ray,the emittance of stored electron beam should be as
small as around 10 nano m·rad. The lattice structureof DSR is designed so as to give such a low emittanceelectron beam. 3 )Other experiments such as ion-ion merging collisions
at small angles are also envisaged. The luminosity is
expected to be around 1 x 10 26 cm 2/s when the numberof stored ions is assumed to be the space charge limit of
4 x 10 12 particles and the colliding angle is 10 degrees.
References
1) K. Yoshida and T. Katayama: This report, p. 256.
2) M. Wakasugi, N. Inabe, and T . Katayama: This report,
p.257.
3) N. Inabe and T. Katayama: This report, p. 248.

239

RIKEN Accel. Prog. Rep. 29 (1996)

Accumulator Cooler Ring and Booster Synchrotron Ringfor MUSES
T. Katayama, Y. Batygin, N. Inabe, K. Ohtomo, T. Ookawa, M. Takanaka, M. Wakasugi, S. Watanabe,
Y. Yano, K. Yoshida, J. Xia, Y. Rao, and Y. Yuan
The Accumulator Cooler Ring (ACR) functions exclusively for the accumulation and cooling of RI beams.
Taking the accumulation and cooling of an extremely
neutron-rich 132Sn50+ (a double-magic nucleus of 40 s
in half-life) beam of 200 MeV/nucleon as an example,
we give some specifications of the ACR. This RI beam
is produced via the projectile fragmentation of a primary beam of 136Xe ions with a peak current of 2 pf-LA.
Typical beam characteristics are estimated as follows:
the production rate is nearly 1 x 10 7 particles per second; the momentum spread is ± 0.1 %; the phase width
relative to RF frequency is ±10 degrees; and the transverse emittance is 4.5 7r mm·mrad in both horizontal
and vertical directions .
Firstly, the above RI beam is stored in the ACR withthe conventional multi-turn injection method. About
1 x 101 particles are injected for each one turn revolution, because the orbit frequency is nearly 1 MHz.
Provided that the acceptance of horizontal phase spaceof the ACR is designed to be 125 7r mm·mrad, andthat the dilution factor during the multiturn injectionis 1.25, the emittance of the stored beam becomes aslarge as the full acceptance. after 22 turns injection. At
this moment, the number of stored particles increases
up to 2 X 102 particles.
Secondly, the stored particles are RF -stacked: 1)
The RF voltage of 24 k V is applied, and the frequency is swept from 30.30 MHz (corresponding to
200 MeV/nucleon) to 30.62 MHz. This frequency
sweep brings about changes in the beam momentum
and average radius by 1.8% and 17 mm, respectively.
This multi-turn-injection plus RF-stacking process isrepeated at 10 Hz (l/Tcoo l) where Tcool is a longitudinal stochastic or electron cooling times. During thisprocess the RF-stacked beam continuously undergoes
the stochastic or electron cooling at the stacked top
energy. Typical parameters of the stochastic coolingand electron cooler are tabulated in Tables 1 and 2.
The longitudinal cooling time by the stochastic method
is estimated to be as short as 0.1 s while the cooling time of electron cooler is several seconds. 2) Aftera sufficiently longer period than the intrinsic half-life,
the number of coasting particles accumulated in the
ACR amounts up to the equilibrium value of 1 x 10 5.
The momentum spread and emittance of the cooled
stacked beams, become less than 0.15% and nearly 1 7r
mm·mrad, respectively. This high-quality stored beamis adiabatically bunched with RF field. It is fast extracted, and is injected into the BSR by the one turn240

Table 1. Parameters of the stochastic cooler .
Longitudinal cooling time
(Number of Ions 1 x 10 8 ) (sec)92
U + (150 MeV /u)
0.06
C 6 + (400 MeV /u)
0.01
Band width W (MHz)2000
Ambient temperature Tn (K)18
Atmospheric temperature T (K)80
Total microwave power P (kW)10
Pickup sensitivity Zp (Ohm)300

Table 2. Parameters of the electron cooler.
Maximum electron energy (ke V)
300
Maximum cooled Ion energy (MeV /nudeon)
500
Maximum electron current (A)10
Cathode diameter (mm)5.81Electron diameter at cooling section (mm)50Length of cooling section (m)3.0
Cooling time (s) for 200-MeV /nucleon 132Sn50+,
initial bop/p = 0.5 % and emittance€ = 1257r mm·mrad
5.4

injection mthod.
The Booster Synchrotron Ring (BSR) serves as asynchrotron to accumulate and accelerate electrons
from a 0.3 GeV linac up to 2.5 GeV. The outline of
the BSR is described elsewhere. 3) At the initial energyof 0.3 GeV the damping times are estimated to be 0.5
s for the transverse direction and 0.26 s for the longitudinal direction, which are short enough for the accumulation of electrons. The acceleration up to 2.5 Ge V
is done within 1 S .4) This top-energy electron beam is
fast extracted and injected into the DSR by the oneturn injection method. The BSR will also be used
for the acceleration of ion beams transferred from the
AeR. The maximum B p of the BSR is designed at
14.6 Tm which is matched with the DSR. The accelerated ion beams will be fast extracted and one turninjected into the DSR, and also slowly extracted forthe experiments.
References
1) K . Ohtomo and T . Katayama: This report, p. 244.
2) K. Ohtomo and T. Katayama: This report, p. 246.
3) T . Ohkawa and T. Katayama: This report , p. 241.
4) S. Watanabe: This report, p. 242.

RI KEN Accel. Prog. Rep. 29 (1 996)

Design of Booster Synchrotron for MUSES
T. Ookawa and T. Katayama
The Booster Synchrotron Ring (BSR) is a part ofMulti-Use Experimental Storage Rings (MUSES).l)The BSR follows the Accumulator-Cooler Ring (ACR).
The BSR functions exclusively for acceleration of ionand electron beams. The accelerated ion and electron
beams will be fast extracted and injected into the Double Storage Rings (DSR) that follow by one turn, andion beams will be slowly extracted for experiments.
Layout of the BSR is shown in Fig. 1. The lattice
structure takes the form to accommodate four longstraight sections and four medium straight sections.
The long straight sections are used for fast and slow
extractions of ion and electron beams. In the medium
straight sections, RF cavities and kicker magnets areinserted.

Table 1. Parameters of the BSR.
Circumference (m)134.787
Max. magnetic field (Tm)
14.60
Average radius (m)21.45Radius of curvature (m)9.58
Max. accelerating beam energy
proton (Ge V)
3.54
1.45
ion (q/ A = 1/2) (GeV /nudeon)
0.80
ion (q/ A = 1/3) (GeV /nudeon)
electron (GeV)
2.50
Betatron tune values (Qx/Qy)
5.438/4.867
0.218
Momentum compaction factor
Transition 'Y
4.579
Max. betatron amplitude (j3x/ j3y,m)18.12/21.97
Max. dispertion function (Dx/Dy, m)
2.52/0.0
Length of long straight section (m)4.0Length of medium straight section (m)
3.15

QD

B
QF
BSD

~edium straight section
QF
B

QD
B
QF

QD
long straight section

Fig. 1. Layout of the BSR.
Parameters of the BSR are given in Table 1. The
ring circumference is 134.787 m, which is 4 times aslarge as the extraction circumference of the Superconducting Ring Cyclotron (SRC);2) the harmonics of the
BSR is 24 while that of the SRC is 6. The maximum Bp-value becomes 14.6 Tm when a dipole fieldstrength is 1.524 T at the maximum. The maximum
accelerating energy is then (to be) 3.54 GeV for protons, 1.45 GeV /nucleon for light ions of q/ A = 1/2,
and 800 MeV/nucleon for heavy ions of q/ A = 1/3.
For electron beams the BSR boosts them up to the

maximum energy of 2.5 GeV from the injection energyof 300 MeV. The acceleration up to the maximum energy is done within 1 s. The betatron tune values are
5.438 (horizontal) and 4.867 (vertical). The maximum
energy is kept to be under the transition energy, since
the transition gamma is as high as 4.58. Natural chromaticitiy values are - 6.543 (horizontal) and -7.010(vertical). The chromaticity is corrected by two families of sextupole magnets, one focusing and one defocusing. Taking the acceleration of 238U92+ beam from150 MeV/nucleon to 1 GeV /nucleon as an example, wegive some RF parameters of the BSR. Typical beamcharacteristics are estimated as follows: The momentum spread is ±0.1 %; and the transverse emittances
are 125 Jr mm·mrad in horizontal direction and 5 Jr
mm·mrad in vertical direction. Provided that the dilution factor is 2 , the maximum RF voltage is required
to be about 200 kV , and the frequency to be modulated
from 27.12 to 46.76 MHz.
Optimization of parameters of the BSR is under way.
References
1) T. Katayama: This report, p. 240.
2) Y. Yano et al.: This report, p. 226.

241

RIKEN Accel. Prog. Rep. 29 (1996)

Computer Study of Magnet Power Supply for MUSES
Booster Synchrotron (BSR)
S. Watanabe
MUSES-BSR is a booster synchrotron with a repetition rate of 1 Hz. In the BSR, electron and heavy
ion beams are accelerated and fast extracted. Thenthey are injected into Double Storage Rings, DSR. The
maximum energy of BSR is 2.8 GeV for protons and
350 MeV /u for 238U58 beams. The magnetic optics of
BSR is described precisely elsewhere in this progress
report. The fundamental points of magnetic issues are
as follows. The lattice structure of BSR is four FBDBFBDB-FBDO-FBDB-FDO structures. Then the synchrotron magnet strings comprise 28 dipole magnets
and 40 quadrupole magnets with four groups. In addition, one dipole magnet and four quadrupole magnets
are needed to measure the magnetic field, which is used
for a current feedback or B-clock detection. A current
excitation pattern has a flat bottom and a flat top field
like the trapezoid wave form. Expected dipole magnet
specifications are tabulated in Table 1. To reduce theinductance of a magnet coil, the excitation coil hasa cross-section which is two times larger than that ofhollow conductor.
Table 1. Specifications of a dipole magnet of BSR.
Maximum field
Minimum field
Magnet length
Magnet width
Magnet height
Magnet gap height
Magnet gap width
Magnet ampere turn
Main coil turn number
Auxiliary coil turn number
Main coil inductance
Main coil resistance

242

l1V
0~==~------4--+------~F=~--

0.15

0.355

0.15

0.358

0.15

O-===~----------------~==~--

Fig. 1. Voltage and current patterns of BSR.

1.5 T
0.042 T
1.8 m
1.0 m
0.7 m
0.07 m0.272 m
83556.4 AT
30

12
8.532 mR
4.677

mn

The designed voltage and current patterns of thedipole magnet strings are shown in Fig. 1. The maximum time-derivative of dipole magnetic field in the
beam acceleration phase is designed as large as 5.99
T Is. The estimated power consumption at the full excitation of dipole magnet system is 7.614 MW. The
var component at the full-excitation is also estimatedat 10.768 MVA. The flat top time will be expanded
to five or ten times longer than that in Fig. 1 in thecase of slow extraction for the production of a long-spill
beam. Figure 2 shows a schematic diagram of a power
supply for BSR. The power supply comprises a thyristor, an LC filter , a dynamic filter and a current regulation loop. The current regulation loop comprises a
voltage feed-forward, ACR and VCR loops. The feed-

a

406V

Fig. 2. Schematic structure of a bending power supply of
BSR.

forward loop plays a role to boost the excitation current for an inductive load with a large time constant. A
self-learning technique with a computer-feedback loop
plays an important role so that the excitation-current
error is to be minimized comparing with a reference
current pattern. I) A computer study of dipole magnet power supply has been done to evaluate the accuracy, response and reliability in the operation modeof pulsed trapezoid wave form. The circuit model em-

ployed in the calculation, is similar to that of a synchrotron power supply of INS-TARN2.2)
The accuracy of excitation current is evaluated as afunction of amplitude resolution of a current patterngenerator, using a digital to analog converter. The current pattern at the acceleration phase comprises linear
or quadratic time dependence. In the quadratic region,
the current change appears suddenly because of a bit
data change of the digital to analog converter. This
step-wise current change must be smaller than 10- 6 of
the full excitation current.
The error of current pattern is exponentially decreased with the number of self-learning process. The
computer study shows that a small change of circuit
parameter is required to adapt the basic model to the
MUSES-BSR power supply. The feed-forward time,
gain of DCCT and the damping time of feed- back circuit have been searched to obtain high-precision current control up to 10- 6 .
Figure 3 shows an example of the self-learning process. The vertical scale is a residual current defined as
the subtraction of the reference current from a flowing
current through the load magnet . For the check of thecircuit parameter, firstly, we investigated the impulse
response of the circuit to determine the delay time ofthe power supply circuit. The analysis of impulse response gave also the information on the componentof oscillations against rapid signal changing such as a
step-wise reference signal from the digital to analog
converter. Secondly, the delay time of the circuit was
adjusted so as to reduce the ringing components appeared in the residual signal.
The magnet strings comprise 7f-7f mode L-C network which has normal and common mode admittances. 3 ) These parameters are examined whether or
not there are resonance phenomena due to the current
ripples at a thyristor block. If the ripple current is
coupled with resonance of these admittances, the errorof magnetic field will be excited. Figure 4 shows thecalculated normal mode admittance of dipole magnet
strings. We can see that the resonance appears aroundthe higher harmonics of 50 Hz component. The resonance frequency which coincides with higher harmonics
of ripple current , must be shifted upward or downward
by additional capacitance at the magnet component.
We are making a small model of magnet strings toevaluate the winding structure of magnet coils and theresonance detune method.
100d~------~------~------~------~

Od~------4--------+--+--+~~~~~~

100m.-------,--------.--------,-------,
Addmittance of MUSES-Bmag

1.0m~------4-------_+--_7'~_lr_l___f___1r1\~--~

1~~~H-z-----1-0~O~H-z----~1.70k~H7Z----~10~k~H~z--~100~kHz

Frequency

Fig. 4. Calculated normal mode admittance of BSR dipole
magnet strings.

References
0.2

0.4
0.6
TlME(SEC)

0.8

Fig. 3. Current pattern errors during the self-learning
process.

1) M. Takanaka and S. Watanabe: INS-T-456 [Accelerator-2] Mar. (1986).
2) S. Watanabe: INS-T-504 [Accelerator-13] July (1991).
3) S. Watanabe: INS-T-533 [Accelerator-20] Jan. (1995).

243

RIKEN Accel. Prog. Rep. 29 (1996)

Simulation of RF Stacking Injection at Accumulator
Cooler Ring for MUSES
K. Ohtomo and T. Katayama
The accumulator cooler ring (ACR) stacks the RI
particles from the super conducting ring cyclotron(SRC) and cools them. The RF stacking technique 1 ,2 )is generally used to stack the injected particles to asynchrotron ring effectively. To optimize the various
parameters of the RF stacking, the stacking process
has been simulated by solving the synchronous oscillation equations with the Runge-Kutta method.
The motion of an injected ion in the RF stacking
process follows the equations:

s

> 230
OJ

~ 220

~

.... , ....

210

;

200

l.Ll

i ..

i

_._._._.- V

190

N

::c

100

Energy- - RF frequency

;

OJ

c:

120

.. ..........

>

SO C

RF

OJ

60

6 29.5

~

-0;>

u

29.0

40 ~

::3
0"

28.5

20

;>.

c:
OJ
OJ

t.!:

2S.0

~

0

10

20

0

30

Time (msec)

dE

dt

Fig. l. RF frequency and voltage pattern.
WreveVacc .
- - 2- 7[-- SIn r.p,

225

1
1
ry=- - -QQ,2 Il'

Here subscript s represents the synchronous particle, cp
and E are the phase and energy of a particle, W rev is theangular revolution frequency of the particle, h the harmonic number, Vacc an RF voltage, and It the transition gamma. We have developed a computer program
based on these equations and the 4-step 4th RungeKutta method. Parameters It and h were fixed to be
4.875 and 24 given from the basic design of ACR. The
spreads of energy and phase distributions (l:lE andl:lcp) of injected particles were set to be ±0.5 MeV lu
and ±10 degrees, respectively.
First , we calculated the one-cycle stacking process
on trial to search the parameters. It was recognizedthat efficient stacking needed a large RF bucket at the
injection and as small a suppression as possible of thisRF bucket at the final stage of the stacking cycle. In
order not to spill any particles from the RF bucket, thebucket height is required to be about 3 times larger
than l:lE of injected particles and the RF voltage to
be over 100 kV. But this voltage should be reduced
suddenly to one third of the initial value after 30 J-lsec
which is quarter of the synchrotron oscillation period
passed. This reduction prevents the emittance of theinjected particles from increasing. The voltage reduction in the latter half of the stacking cycle is importantto suppress the momentum spread of particles. Good
results were obtained when the dilution factor was set
to be 1.5 and the RF voltage at the final stage to be 3.6
k V. A typical pattern of time-dependent parameters isshown in Fig. 1.
In Fig. 2 is shown the motion of the injected particles
in phase space during the one stacking cycle. In thiscase after 34 msec, 10% of the particles began to spill
244

Q

Q'J

220
"':

U

QQ

U

QQ

Q

..,Q

_t>.

n
Q

Q

Q

~"

t§Q

u

I>

El

Q

I>
Q

I>

Q

Q

S' 215

>
(1)

:2

+

1= O[msec)';:: 2 10xt= 5[msec)

i:ll" t= IO[msec)

c:

"

(1)

u.J 205

0

"
Q

200

t=1 5[msec)
1=20[msec)
1=25 [msec)
t=34[msecj

••
I

-180

o

-90

180

90

Phase (deg)Fig. 2. Motion of the injected particles in phase space
during one stacking cycle.

223

222

S' 221

>
(1)

6 220
;>-.
0I.l

~ 219
c:
u.J
218

Dafter 15 stacking
Dafter 30 stacking

217

0

100

200

300

Number of particles

Fig. 3. Energy distributions of particles after 15- and30-cycle stacking.

out from the stable area in phase space toward thelower energy.
Next , we calculated the multi-cycle stacking process.
The energy distributions of all particles after 15 and 30
stacking cycles are shown in Fig. 3. About 10% of theparticles were shifted to a low energy (less than 219.3
MeV lu) side during 30 stacking process. These particles are expected to be unable to receive the coolingforce effectively, and thus expected to be spilled out.
In summary, it can be expected that the injection

efficiency is 90%. This value is acceptable for the stacking to AeR. As a next step we will take account of thecooling effect in this simulation.
References
1) E. Ciapala: Proc. CERN Accelerator School 85-19, 1,
195 (1985).
2) G. Bisoffi: "Radiofrequency Stacking: A Method to
Reach High Intensities in the Storage Ring TSR" , doctoral thesis (1989) .

245

RIKEN Accel. Prog. Rep. 29 (1996)

Electron Cooling at RI Beam Factory
K. Ohtomo and T. Katayama
The RI Beam Factory project demands very rapid
cooling because of the short life time of RI. We haveevaluated the cooling time at the Double Storage
Ring!) (DSR) by using the technique of the electron
cooling method. 2 ,3) The cooling time has been obtained by solving the kinetic equations of an ion withthe cooling force.
An ion under the electron cooling process follows theequations: 4 )•••••• 6pipl,-o=O,05%_ . . _ .. 6pipl,:(,=0 , 1%_._. 6pipl" o=O,2%

0 ,005..... 6pipl,=o=0.3%
0 ,004- - - 6pipl,=o=0 4 %

~

Co

0,003

6pipl,.o=O,5%

61'=0=4.4 7mrad

Ci<l0 ,002

0,001

d8

dt

8
-k

[0 + ;, (';2r]

0 ,0003/2

0 ,004,2 ( P )2]
2

82 _..1...
2(10 - log Z) + 3[

b)0 ,005~

0 ,00382 + ...l..
,2 (~p)P

0 ,002

0 ,001d~-p-dtTime [sec)Fig. 1. Transient cooling process of 200 MeV /u 132Sn+50
ions simulated for different initial values of 6..p/p: a)the cooling of 6..p/p ; and b) the cooling of e. The initialvalue of is taken to be 4.47 mrad. The cooling time isdefined as an elapsed time before 6..p/p and e get close
to zero.

e

Here 8 and 6.p I p are the transverse and longitudinal
momentum deviations , Z is the charge state, A themass number, Te the classical electron radius , Tn theclassical nucleon radius, j e the electron flux density,£ the length of an electron cooler section, and L thecircumference of a storage ring. To simulate the cooling process, we have developed a program in whichthese equations are solved by using the Runge-Kutta
method.
In the present simulations, the £ and L are set to be
3 and 178.8 m, respectively, which are derived from thelattice design of the DSR. The initial value of 8 is set
to be 4.47 mrad, assuming that the beam emittanceof ion is 100 mm·mrad and the beta function at theelectron cooler is 5 m. The j e is assumed to be 5000
A/m 2 , considering the space charge effects.
Figure 1 shows an example of the simulation, in
which 200-MeV lu 132Sn+50 ions are selected as a test
particle. The 6.p I p and 8 of ions are plotted as a function of time. The simulation has been made for different initial value of 6.plp ranging from 0.05 to 0.5%.
The initial value of 8 is fixed to be 4.47 mrad as mentioned above. The slope of the curves in the figure
246

clear ly indicates that the rate of cooling gets faster as
the 8 and 6.p I p decrease. This is a characteristic of
the electron cooling. It is also shown that the cooling time decreases quadratically as the initial value of
6.p I p becomes smaller.
A contour plot in Fig. 2 shows the simulated cooling

80
N
Q)

~C/'l
Q)

b()

~

60
40

..c
u

20

50

100

150

200

250

mass number A

Fig. 2. A contour plot of cooling time given as a functionof mass number and charge state number. The coolingtimes of typical ions are shown as closed circles in the
figure.

time as a function of mass number and charge state
number. The ion energy and the initial value of ~plp
are taken to be 200 MeV lu and 0.5%, respectively.
Most ions are fully-stripped at this energy. Very heavy
ions such as bismuth are found to be cooled rapidly.
The typical cooling time is about a few seconds. This
will allow a large number of RI beams in this mass region to be cooled efficiently. On the other hand, lightheavy ions are found to be cooled very slowly and their
cooling times are much larger than life times of RI.
For example, it takes about 25 seconds to cool 12C+6
ions. The electron cooling cannot be used for mostof RI beams in this mass region. The cooling time of
medium heavy ions is found to be 6 to 10 seconds. In
this case, RI beams far from the stability line cannot

be cooled efficiently.
I t has been shown that the electron cooling is notapplicable to all kinds of RI beams. We conclude thatthe stochastic cooling method needs to be used in addition to the electron cooling.
References
1) T. Katayama et al.: RIKEN Accel. Rrog. Rep., 28, 180(1995) .
2) A. H. S¢rensen and E. Bonderup: Nucl. Instrum. Methods , 215 , 27 (1983).
3) M . Bell et al.: ibid., 190, 237 (1981).
4) T. Katayama: "Electron Cooling at MUSES", internalreport (1995) unpublished.

247

RIKEN Accel. Prog. Rep. 29 (1996)

Design of a Lattice of the DSR
N. Inabe and T. Katayama
A new lattice of Double Storage Rings (DSR 1 ») has
been designed to fulfill new requirements from experimenters who use X-rays radiated from stored electron beams in the ring. The requirements have twomain points. One is to reduce natural emittance of thestored electron beam to about 1/30 of the old one inorder to get X-rays with narrow widths of energy andsize. The other is to insert an undulator with lengthof 5 m in a long straight section in order to produce
X-rays. Since the required reduction can't be done forthe old lattice, we changed the lattice configuration
very much. As the result parameters of the new lattice such as circumference, tune and so on are muchdifferent from those of the old one. In addition to thetwo main changes, we changed the magnetic rigidityfrom 12.76 Tm to 14.60 Tm, which corresponds to its
value of 800 MeV /u with q/ A = 1/3.
Figure 1 shows a schematic drawing of the DSR. As
shown in Fig. 1, the DSR is composed of four arcs, twolong straight sections and two short straight sections.
The long straight section consists of the und ulator section and a colliding section. The short straight section
is for cooling of ion beams .

ing quadrupole magnet between the two dipole magnets (QFA) , it is difficult to correct the natural chromaticity due to small dispersion between two dipole
magnets. For this reason we introduce a horizontal
defocusing quadrupole magnet (QDA) that enlarges
the dispersion between the two dipoles and achieves
the DBA by both the QFA and the QDA. Anotherhorizontal focussing quadrupole magnet (QF) is introduced to fulfill the periodic condition of the cell. Eachparameter shown in Table 1 is chosen so as to fulfill
constraints that are the small natural emittance, easy
chromatici ty correction, small magnetic field strengthof quadrupole magnets and short length of the cell.

QF O

D

QDA

10

0

0 QDA

' QFA /

D

0 I

Orbit Length (m)Fig. 2. f3 and dispersion functions of the unit cell in the
DSR.

Table 1. Parameters of the unit cell in the DSR.

j
I -COll iding poi nt

Fig. 1. Layout of the DSR.

Drift length (m)
QFrvD
0.3
DrvQDA
0.2
QDArvQFA
0.4
QFA 's
0.7
QF's
0.3
Dipole radius (m)9.73
Length of Q (m)
0.2
QF
QFA
0.2
QDA
0.3
Field strength of Q (11m 2 )
QF
3.356
QFA
4.172
QDA
-3.013The natural emittance is reduced by small dispersion
in a dipole magnet in the arc.2 ) We made the small dispersion by constructing a unit cell with a Double Bend
Achromart (DBA) system. Figure 2 shows f3 and dispersion functions of the unit cell in the DSR. Although
the DBA can be achieved only by the horizontal focus-

The arc consisted of four cells mentioned above. In
order to reduce the natural emittance a large numberof cells is suitable. However it is impossible to make thearc with many cells due to limitation of a construction
area. The number, four , is maximum for the area.

IA
co lliding point!

DSR

Circumference
Bp_max258.732 m
14.6 Tm

I.........~"

':.e

o

248

10

20

30

40

50 M

In the undulator section small sized and parallel
beams are required. The required value of Twiss parameter, {3, is 5 m and that of Q at the midpoint of
the section is O. To match emittance between the arc
and the section a triplet quadrupole is inserted at theentrance of the section. Figure 3 shows the {3 functionof the section.

0

QFMll
OQFM1 2
QDMllU

2.5

5.0

10.0

7.5
Oribit Length (m)The (3-functions of the colliding section and the shortstraight section are the same as those of the old one. 1 )For the reason luminosity does not change from the oldone. Matching with the connected section is achievedby a triplet quadrupole located at the entrance of thesection. Figure 4 shows the (3-functions of the colliding
section (a) and the short straight section (b).

QF13

o

O~QD12

o

QF22

QF22

QF13

0

0

0

QD21U UQD23

QD23U UQD21

10

Table 2. Parameters of the DSR.

12.5

Fig. 3. /3 functions of the undulator section in the DSR.

QFll

These are summarized in Table 2. The circumference is258.732 m, which is about 80 m larger than that of theold one. This is due to the long unit cell and insertionof the undulator section. The betatron tunes, 18.130
for horizontal and 10.197 for vertical, are much larger
than those of the old one. The natural chromaticities
are also very large. Enlargement of the tunes and thenatural chromaticities are due to strong field strengthsof the quadrupoles in the unit cell. Parameters of thestored electron beam are summarized in Ref. 4. The
natural emittances for 2.5 GeV electron beam are 8.54
n m*rad for horizontal direction and 25.5 n m*rad forvertical one, both of which are much smaller than thoseof the old one. The values are small enough for theexperimenters' requirement.

QFll

QD12

o

l:s 0
VBU

Circumference C (m)Max. Bp (Tm)
Average radius R (m)Max. beam energy (GeV /u)protonion (q/ A = 0.5)
(q/ A = 0.387)(q/ A = 0.333)
Betatron tune value (Qx/Qy)

258.732
14.60
41.20
3.50
1.33
1.00
0.80

18.130/10.197
Mometum compaction
0.00171
24.20
Transition T
Max. betatron amplitude (/3x//3y, m)
22.0/17.9
Max. dispersion function (Dx/ D y , m)
0.537/0.697
Betatron amplitude at Interaction
point (/3x * //3y *, m)0.600/0.600
Length of field-free section
at colliding section (m)5.016
Natural chromaticity (Q~/Q~)-45.59/-30.94

20Orbit Length (m)QFM31 0n

0 QFM32
UQDM31

2.5

QFM32
0 QFM31
QDM31U

7.5
Orbit Length (m)

10.0

12.5

Fig. 4. /3 functions of the colliding (a) and cooling (b)sections in the DSR.

After matching all the sections we calculated several
parameters of the DSR with a calculation code MAD.3)

In the DSR several operation modes are required.
For colliding electron and ion, a large emittance compared with that mentioned above is required for theelectron beam. For ions the small natural chromaticity is required to enlarge a dynamic aperture. We are
now searching different operation modes to meet therequirements.
References
1) T. Katayama et al.: RIKEN Accel. Prog. Rep. , 28, 180(1995).
2) A. Jackson.: Particle Accelerators, 22, 111 (1987).
3) Hans Grote and F. Christoph Iselin: CERN/SL/9013(AP) (User's Manual Version 8.1).
4) M. Wakasugi et al.: This report, p. 257.

249

RIKEN Accel. Prog. Rep. 29 (1996)

Beam Current Limitations Due to Single-Beam Collective Effects
at Double Storage Rings at MUSES
M. Takanaka and T. Katayama
The RIKEN Accelerator Research Facility grouphas been proposing "RIKEN RI Beam Factory" as anext project. I) Ion-electron colliding and ion-ion merging ex:periments are planed at Double Storage Rings(DSR) of M ulti-USe-Experimental-Storage ring system(MUSES). These experiments require high luminositywith small momentum spread and emittances. For
this purpose, an accumulator ring will be installed upstream the DSR where the intensity of ion beams isincreased with a cooling-staking technique and the momentum spread and emittances are cooled down. The
expected full momentum spread may become at most
10- 3 and the transverse emittances 1 x 10- 6 7rmrad.
The improvement of beam qualities does not always
mean the increase of luminosity, because it makes
single-beam collective effects strong and hence limits
the beam currents in the ring.
In this paper, limitations of ion beam current are estimated due to beam-beam effects during the collision,
the direct space charge effects, and beam instability
in the designed ion ring. The luminosity is evaluatedfor the threshold beam currents. Finally, a proposal
is made to improve the luminosity. More detailed description has been given elsewhere. 2 )In DSR bunched electron beams circulate in the one
ring and ion beams circulate in the other ring which
will collide at two interaction points with zero colliding angle. The stability of betatron motion of the ionsin the ring, requires that the linear betatron tune shift
due to the beam-beam effect should be less than about
0.05. From this point of view, the number of electrons per bunch is evaluated in Table 1 where the rms
emittances of electron beams are assumed at 8 x 10- 9
7rmrad for 300 MeV and at 530 x 10- 9 7rmrad for 2500
Me V, respectively. On the other hand, the stored current of the electron beam is expected to be at least
300 mA, corresponding to the number of electrons of
7 x 10 10 per bunch. Then the number of electrons
at the low energy of electron beams is limited by thebeam-beam effects on the ion beams.
In order to make an effective collision, the full bunch
length of ion beams is required to be less than 40 cm,

Table 1. The threshold of electrons' number per bunch dueto the beam-beam effect and the number per bunch forthe 300 rnA electron beam.
Ion x electron
2

400 MeV /u 4He +150 MeV /u 238U92+

250

300 MeV e- 2.5 GeV e- 300 rnA
2 X 1011

1 X lOll

7 X 1010

which corresponds to the bunching factor 1/15. The
incoherent betatron tune shift due to the direct spacecharge is tolerable by I~vl = 0.2, when resonance compensation is carried out completely. The space charge
limits of ions' number per bunch are shown in Table 2.
Table 2. The threshold of ions' number per bunch due tothe direct space charge.
400 MeV /u
150 MeV /u

The structure of vacuum chamber and numbers ofelements have not yet determined in DSR. Here, theion-beam coupling impedances with the chamber are
estimated under a rough assumption as shown in Table 3. The longitudinal impedance of the RF cavity is
assumed to be like that of a A/4 coaxial cavity withthe use of a perpendicular bias field on the ferrite.
Table 3.
The imaginary parts of the longitudinal
impedances Im(ZL/n)[fl] and those of the transverse
ones (ZJ..)[Mfl/m] of the ion ring of DSR at the low
frequency.
Injection energy
Direction
Space charge
Broad band

150 MeV lu

400 MeV lu

Horizontal Transverse Horizontal Transverse
1900
-3.2

6600
-0.2

860
-4.0

2300
-0.2

The microwave instability is undesirable, because it
induces bunch lengthening when the ions' number per
bunch goes beyond a threshold, and the lengthening
decreases the luminosity. It is shown that the mi~rowave instability does not occur for the ions' number
less than the space charge limit with the momentum
spread of 1 x 10- 3 .
Single-bunch instability and multi-bunch instability
are induced for the ions' number of space charge limit.
The growth time of the most unstable coupled-bunchmode at each synchrotron mode is shown in Table 4,
which is calculated with the program ZAP modified tobe applicable to ion beams by the authors.
Transverse single-bunch instability is Landau
damped because the coherent tune shift is less than
the incoherent betatron tune shift by a factor of 3.
Transverse multi-bunch instability is induced
through the resistive wall impedances and RF narrow
band ones. Here, the growth times of instability justthrough the former are evaluated as shown in Table 5.
The electron cooling can be applied to damp theTable 4. The growth times [s] of the most unstable mode(m,n) of the longitudinal single-bunch instability and multi-bunch instability in the n-th mode, where m shows thecoupled-bunch mode and n the synchrotron one.
400 MeV/u
Single-bunchMode(1) 0.7
Mode(2)1Mode(3) 10Mode(4) 30

4He 2 +
M ulti- bunchMode(0,1)
0.02
Mode(0,2)0.05
Mode(0,3)0.3Mode(0,4)
0.9

Table 5. The growth times [s] of the most unstablemode(m,n) of the transverse multi-bunch instability under the chromaticity of zero.
EnergyIon
Mode(23,0) or Mode (24,0)

400 MeV lu 150 MeV lu
4He 2 +
238U92+
1150 MeV luSingle-bunchMode(1)1Mode(2) -0.3
Mode(3) -4Mode(4) -0.8

238U92+Multi-bunch
0.07
Mode(28,1)Mode(27,2)0.4
Mode(29,3) 0.3
Mode(28,4) 0.6

Table 6. The luminosity [cm- 2 S-l] at the space charge
limit of ions.
Ion x electron
400 MeV lu 4He 2 +150 MeV lu 238U92+

300 MeV e

2.5 GeV e

3longitudinal and transverse instability. The coolingtime is required to be less than half the growth time;3)
Tcool ~ 0.01 [s].
In the presently designed ion ring of DSR, the longitudinal single-bunch instability and multi-bunch instability are induced at the number of ions at the spacecharge limit and the bunch length of 40 cm. The transverse multi-bunch instability may be induced, which isdependent on the chromaticity. The electron coolingwith the cooling time of 0.01 s can damp the instability. As a result, the luminosity shown in Table 6
is determined by the space charge limit of ions andthe limit of electrons' number. The luminosity for 150
MeV lu 238U92+ is much less than 1 x 10 27 cm- 2 S-l.
In order to improve the luminosity, the design of DSR

lattice should be modified as follows;(1) The beta function at the colliding point is reduced
by one order,(2) The optics of the lattice of the electron ring is variable enough to increase the emittance of the 300 MeV
electron beam up to around 0.5 x 10- 6 7rmrad in orderthat the beam-beam effects become weak,(3) The numbers of bunches of both beams are increased by a few times.
References
1) Y. Yano, A. Goto, and T. Katayama: RARF Accelerator Group, RIBF-A-1-1995 (1995).
2) M. Takanaka and T. Katayama: Proc. 10th Symp. on
Accel. Sci. and Technol., p. 318 (1995).
3) S. Cocher and I. Hofmann: Particle Accelerators, 34,
189 (1990).

251

RIKEN Accel. Prog. Rep. 29 (1996)

Merging Beam-Beam Interaction at DSR
Y. Batygin and T. Katayama
Proposed Radioactive Isotope Beam Factory1) isaimed to be used for a wide range of experiments withunstable nuclear beams. Among variety of planning
experiments the ion-ion merging collisions are very important. In this paper we analyze the luminosity constraihts due to beam-beam interaction as a function of
main parameters of the storage ring.
We consider two coasting merge ion beams withparticle densities n1 and n2 and with beam velocities "1 = C/31 and "2 = C/32, colliding with angle a (seeFig. 1). Luminosity L is defined as a ratio of interaction rate to cross section for the particle interaction:
L = l/a dN/dt. Using expression for invariant crosssection 2) the number of collisions dN during the time
dt is
dN
dt
=

1ay/
v

-+

-+

(V1 - V2)2 -["1 X"2]2c2(1)n1 n2 dV,

where integration is performed over the volume of interaction. It is convenient to express the luminosity as
a function of collision angle a, number of particles per
beam Nl, N 2, ring circumference 27rR, and effective
size of the beam heff at the interaction point:L=.Jf3? + f3~ - 2f31f32 cos a - f3?f3~ sin2 acN1 N2 (2)(27r R ) 2 sin a heff.

The numerical model for beam-beam interaction study
includes a transfer matrix for particle revolution in thestorage ring and particle-in-cell treatment of a spacecharge problem at the crossing point. 3 ) Linear approximation to the betatron tune shift is a scale parameterto define the strength of beam-beam collisions:yhxFig. 1. Merge beam-beam interaction.

~=Nro
27r 2a sin a f32 "(3 Q'(3)where ro = q2 /47rco mc 2 is the value of classical radiusof particle, N the number of particles per beam, a thehalf size of the beam and Q the betatron tune.
The RI beam factory is supposed to have two colliding points; therefore the values of tune are half of betatron tunes in the ring: Qx/2 = 2.8815; Qy/2 = 3.175 .
For two coasting merge beams (see Fig. 1) only ydirection is responsible for degradation of beam luminosity because of compensation of the beam-beam kickin x-direction. The closest resonance value mQy = n
to a betatron tune value 3.175 is 6Qy = 19, i.e. the 6thorder resonance is achieved for Qy = 19/6 = 3.16666.
Max tune shift from the working point to resonance is~ = 3.175 - 3.1666 = 0.00833. In Table 1 the results ofcalculations for ~ = 0.005 (non-resonance case) andTable 1. Results of PIC simulation of beam-beam effects.
Beam
distribution

Distribution inreal space

Tune

Turns

Numberof particles

Gaussianp(r) = Po exp(_ r 2/2a 2)

0.005

4.10 4

10 3

1.0

KV

p(r) = po

0.027

2.5.10 4

5.10 3

1.0~

Envelope Emittance
growth
growth(per 104 turns)
1.0002(no growth)
1.0(no growth)
Water
Bag
ParabolicGaussian252

p(r) = Po(1 - r 2/R6)
p(r) = po(1 - r2/R6)2
p(r) = po exp(_r 2 /2a 2 )0.027

2.5.10 4

5.103

1.005

1.025

0.027

2.10 4

5 .103

1.01

1.025

0.027

104

5.10 31.03

1.05

0.00004( r----...,....

(a)0.00002>n.

0.00050 j----t_~oc--+-___:=___+----l

(b)

I
/

0.00000-0.00002"'--0.00004
-0.3

·0.2

0.00025 I------t:tt---:-;-r'--'--=;d:;:--'~-_H_----i

6: 0.00000 t--~-+~-0.00025 }----tr-----''-o,--'F'~--'-'--_'.R_----l

l/

-0.1

-0.00050 I---------+---.:=:..:..-+-~~'__I_----l

a

0.1

0.2

0,3

a

·0.2

Y, CM

0.2

Y, CM
0.023 r-r-r-r-,-,-r-r-r-r-,-,-,-,-,.....,-,,-,-,-,-,,.....,,,.....,CTl

(d)

(c)
0.115 f----+---+-----+-~_t,__,.,.....,

0.022 f----+---+--_+_
0.1 10f--or.-o--!t-~E§ 0.021 j-----;----n::dd.

:::;:
Q

>

0,105

'5.
0.100

j-----;---+----t----t------jg

JJ 0.020
0.095

j----+---j----+---j----i

0.090 0~~5OOO~'---'--,1~OOO~0!--'-'--:1~5000~'-'--:2'::-:OOO'::-:0L....i..-'---:2'::-:500L.,.,J0

0.019 0~~50'::-:OO!--'-.....,1~OOOO~'-'--:1~5000~'-'--:2'::-:OOOO~~2'="5OOO7:
TURN

TURN

Fig. 2. (a) Momentum kick, (b) phase space trajectories, (c) beam envelope, and (d) RMS beamemittance for the beam-beam interaction of particles with Gaussian distribution: Qy = 3.175,
Qx = 2.8815, ~y = -0.027, Nparticles = 5000, mesh NX x NY = 64 x 64.

= 0.027 (resonance case) for different particle distributions are presented. The results of simulation indicated that below the resonance threshold ~ < 0.008
beams were stable, i.e. no envelope and RMS emittance growth were observed. Under resonance conditions ~ > 0.00833 the beam-beam instability was observed (see Fig. 2).
Assuming ~max = 0.008, a y = 10- 3 m, a = 10°,f3, = 1.7, ro = 1.5 10- 18 m (proton) the limited number of particles due to beam-beam interaction is (seeEqn. (3)):~

N < 27r2~maxQyay sinaf3
ro2,3 6.1014 .
=N 2 c a26l
max
tg- = 2 X 10.
(27rR)2 heff 2
sec cm 2(6)

From results of simulation we observed the increaseof transverse beam size 1- 3% per 10000 turns at theresonance conditions. If we assume that for serious
degradation of luminosity the beam size is allowed to
expand twice, the upper limit of beam lifetime in theresonance is
5100%
N max = --0:;-10000 = 5 x 10 turns.

(7)

2/0

(4)

This value is larger than the space charge limited number of particles in a ring of radius R = 28m due to theincoherent space charge tune shift (Laslett tune shift)~lImax = 0.25:
N < 47r ~lImax ~ f32,3 ay 2 = 3 . 10 12 .
ro

L<

(5)

Taking the limited number of particles N max =3 . 1012 , a = 10°, heff = 4· 10- 3 m and assuming f31 ={32 ~ 1, the limitation in luminosity is (see Eqn. (2)):

If the resonance is avoided, the beam life time is limited
by other reasons.
References
1) Y. Yano and T. Katayama: Present Status and FUture
Plan of RIKEN Accelerator Research Facility, Proc.
EPAC94, London, p. 515 (1994).
2) L. Landau and E. Lifshitz: The Classical Theory of
Fields, Pergamon Press (1975).
3) Y. Batygin and T. Katayama: Proc. 10th Symp. on
Accelerator Science and Technology, Hitachinaka, p. 356(1995).

253

RIKEN Accel. Prog. Rep. 29 (1996)

Beam-Beam Interaction of Electrons and Ions at
Double Storage Ring
Y. Batygin and T. Katayama
One of the main experiments at the new RI beamfactoryl) is a collision of 2.5 GeV electron beam withunstable ion beams. This experiment is intended to
be us~d for determination of the charge and current
distribution in the radio active nuclei. The physics ofbeam-beam interaction in the collision point is an important issue for determination of the value of collider
luminosity.
The operating point of the Double Storage ring of
RI beam factory is chosen to be Qx = 14.653 and Qy =16.283. Because the ring is supposed to have two colliding points, the tune shift between sequence beambeam interactions is equal to half of their values, Qx/2
= 7.3265 and Qy/2 = 8.1415.
Beam-beam interaction can be considered as an action of thin nonlinear lens at the interaction point. Influence of the opposite charged beams on each otherresults in increasing of betatron tune of particle oscillations. Because the electron beam is typically muchstronger than the ion beam, it is enough for estimation
to consider the behavior of ion beam in the unchanged
field of the electron beam (strong-weak model). For
the beam-beam interaction the linear part of the betatron tune shift ~ is a scale parameter, which defines
the strength of the beam-beam interaction: 2)~ = r pf3x*

N e (1 + f3ef3i)
47r r if3tO';,(1)

where Ne is the number of electrons per bunch, f3x thebeta-function at the interaction point , Z/ A the chargeto-mass ratio of ion, f3e and f3i the velocities of electrons
and ions, ri is the reduced ion energy, O'e the half sizeof electron beam envelope and rp = e2/47rco mc 2 = 1.5.10- 18 m (classical radius of a proton). Limitation in ~results in constraints of luminosity L, which is defined
as follows:(2)
where f = w s /27r is the particle revolution frequency
in a ring, Ni the number of ions per bunch and Nbunch
the number of bunches per beam. To define the maximum value of betatron tune shift, the numerical calculations of ion trajectories in the collider ring including beam-beam interaction were done. Modulation ofbetatron tune due to coupling with synchrotron oscillations (synchro-betatron resonances) was taken into
account as well. The beam-beam interaction model isa nonlinear four-dimensional map of the particle revolution in a ring with beam-beam kick ~Px , y arising254

from Gaussian particle distribution:
R sin 27rQx
xn+1 = xn(cos 27rQx) + p~( Q),Psx
p~+1 = xn( - Psix sin 27rQx) + p~( cos 27rQx) + ~Px ,Qx,y = Qx,y + As sin (27rQ sn),
A
U

Px -_

(\

2rpfN e (1+ f3if3e) x2 [1 - exp (-~)l
~2 ' 3)
r

fJi

20'e

analogously for yn+1 and p~+1, where (x,y) are theparticle position, Px , Py, Ps the reduced momentumof particles (divided by mc), R is the radius of ring,Qs the betatron tune, As = Qsas/2f3x (depth of tune
modulation 3 )) , and as the bunch length.
Beam-beam interaction is a source of nonlinear resonances. Presence of betatron tune modulation increases the density of nonlinear resonances which obey
the resonant condition (j, n, k and m are integers):
jQx + nQy + kQs = m.

(4)

The working area in phase space is covered by an infinite number of resonances for which the tune value
is a rational fraction. If the resonances have sufficient
width, they overlap in the tune space and the particle
motion becomes unstable (stochastic motion).
General treatment of the stochastic problem 4 ) employs Hamiltonian which includes the betatron tune
modulation:
H = (Qx + As sin 27rQ st -~) J + ~U(J)(5)+ ~Vn(J) cosnW,
where J and Ware the action and angle variables,~U' (J) is the amplitude dependent tune shift; ~V' (J)the 'resonance width', and nand p are integers . Functions U (J) and V (J) are defined by equations:

U'(J) = ~[1 - e- J / 2I o (J/2)],(6)

V'n (J) = (_ 1)n/2+1 ~e-J/2I
J
n/2 (~)
2 .

(7)

Stochastic threshold (Chirikov criteria5 )) for the linear
tune shift expresses a condition that the separation ofresonant islands should be larger than the width ofresonances:

c<~

~ -

4nM

M1/2

(8)

where n is the order of resonance, M is the number

of collisions per turn, and Jdx) the Bessel function of
k-th order.
Figure 1 illustrates the mechanism of the beamstochasticity. Parameters of the problem were chosen
as follows: AjZ= 4, f3ni = 1.7, f3x = 60 cm, as = 40
cm, Qs = 0.01 and As = 0.01. Depending on the combination of parameters, the behavior of particles canbe either stable or chaotic (unstable). For small valuesof ~ = 0.005 ... 0.01 the phase space trajectories are ellipses (see Fig. l(a) and (b)). With increasing ~ until
0.03 the characteristic structure of the 7th and 14thorder resonances at phase plane appears (Fig. 1 (c)).
With the further increase of ~ up to 0.05 the high order resonances overlap each other, which results in thestochastic behavior of particles (Fig. l(d)).
From numerical simulation the stochastic threshold
can be estimated as ~max = 0.01. An analytical valueof the threshold, calculated from formula (8), shows
the upper value of ~max = 0.00625 (see Fig. 2). It isclose to the experimentally observed values of ~max =0.005 ... 0.05 in storage rings.
Taking the value ~max = 0.01 as an upper limit forthe betatron tune shift, f = 1 MHz, the limitation inluminosity is as follows (see Eqns. (1) and (2)):

L < fNiNbunch')'i A t~ 5 . 10 17 . N~otal . ~2f3xrpZ ~max1')'1 Z~ 2. 10 18 . N~otal_1_
1

cm 2 s '(9)where N~otal = N i N bunch (total number of stored
ions in a ring), limited by the lifetime of unstable ions and finite value of acceptance of the ring.

0.0004(a)(b)........ --~~- ---~~-

",

0.001
0.0002>a.

~0.00000.000-0.0002-0.001-0.0004

-0_1

-0.05

0
V, eM

0.05

,

-0.4

0.1

'--...--~

-0.2

--

0
V, eM

../
0.4

0.2

(d)

(c)

0.002
0.001
0.001

>a.

0.000

~

0.000

-0.001-0.001-0.002
-0.4

-0.2

0
V, eM

0.2

0.4

-0.5

0
V, eM

0.5

Fig. 1. Phase space trajectories of beam-beam interaction: Q = 8.1415, Qs = 0.01 , As = 0.01; (a) ( =0.005, (b) ( = 0.01, (c) (= 0.03, (d) ( = 0.05. Trajectories are plotted once per synchrotron period;
the total number of turn is 200000.

1_5
STABLE

/

1.0

//

0.5

0.0 0

/.

/

/

~

~
...........

References
UNSTABLE

3
XlSIGMA

4

Fig. 2. Stochastic threshold (Chirikov criteria) as a function of amplitude for beam-beam resonance of the 7thorder, Qs = 0.01, As = 0.01.

1) Y. Yano, T. Katayama: Present Status and Future
Plan of RIKEN Accelerator Research Facility, Proc. theEPAC94, London, p. 515 (1994).
2) E. Keil: "Theoretical Aspect of the Behavior of Beams
in Accelerators and Storage Rings", CERN 77-13,
Geneva, p. 314 (1977).
3) S. G. Peggs and R. M. Talman: Ann. Rev. Nucl. Part.
Sci., 36, 287 (1986) .
4) L. Evans: "The Beam-Beam Interaction", CERN 84-15,
p. 319 (1984) .
5) B. Chirikov: Phys. Rep., 52, 263 (1979).

255

RIKEN Accel. Prog. Rep. 29 (1996)

Luminosity of Electron-Ion Collision in MUSES
K. Yoshida and T. Katayama
Luminosity for the head-on collision of electrons andunstable nuclei in the Double Storage Ring (DSR) of
MUSES has been estimated.
Luminosity L of the head-on collisions is obtainedby1
1
L = n1n2Nc---heffweff

Er f ((f31 +f32)d

2 +f3 2 a 2
2v'2.VI f3 12 a Z2
2 zl

)
'

J

V27r O"~l + 0"~2' andweff = V27rvO"i1 + O"i 2,h ef f =where ni(i =1 ,2) is the number of particles in one beam
bunch in the DSR, (3i is the ratio of beam velocity to
the speed of light, Nc is the number of collisons which
occur in a unit time, 0" Xi' 0"Yi' 0" Zi are the bunch sizesof x, y, and z direction, and d is the length of theinteraction region. Er f represents the error function.
The bunch sizes will be O"x = O"y =0.774 mm, and O"z =50 cm for ustable nuclei, and O"x = 0.651 mm, O"Y =0.458 mm, and O"z = 2.1 cm for electrons. The numberof electrons in a bunch is expected to amount up to 1.2
12
X 10which corresponds to the beam current of 500
rnA.
The number of unstable nuclei in a bunch is estimated as follows. At RI Beam factory, RI beam
will be produced through a projectile fragment process with primary heavy ion beams of 150- 400 MeV lu
from SRC, and will be momentum- and charge stateseparated by the Big-RIPS. The production rates of
RI beams are calculated with the code INTENSITY2
assuming the acceptance of the Big-RIPS as 10 mradin angle and 1% in momentum. The primary beamand the thickness of the Be production target are optimized so as to obtain the maximum production rate.
In the calculation, the intensity of the primary beam
is assumed to be 100 particle j.tA.
RI beams separated by the Big-RIPS will be thenstored in the Accumulator and Cooler Ring (ACR) of
MUSES with the method of combination of multi-turninjection and RF stacking. Momentum cooling will be
continuously applied to the stacked beam during the
RF stacking process. The maximum intensity of theaccumulated RI beam in the ACR is determined by thebalance of intrinsic life time of RI beams and the injection rate. Since we will take the time interval of256

the injection as the same as the momentum coolingtime, the cooling time should be as short as possible
to get the maximum intensity of stored beam.
Both of the electron cooling and the stochastic cooling were studied for the momentum cooling method.
As a result, it is turned out that the stochastic cooling is always much faster than the electron cooling forthe present case. The cooling time of the longitudinal stochastic cooling is calculated with the equation
presented in Ref. 1.
The accumulated RI beam will be fast extracted
from the ACR and injected into the Booster Synchrotron Ring (BSR) of MUSES. In the BSR, thebeams will be accelerated to the energy required forthe experiment within 0.5 sec, and then will be injected into the one ring of the DSR to collide withelectrons stored in another ring. Since the RI beams
are bunched by 30 pulses in the DSR, the maximum
number of unstable nuclei in a bunch is obtained by
dividing the maximum stored intensity in the ACR by
the 30.
In Fig. 1, the calculated luminosity is plotted forvarious nuclei in an N-Z plane. Also shown in the Fig.
1 are the equi- life time lines. As seen, the luminosity
L ;::: 10 27 cm 2 Is, which is the minimum luminosity required to measure the charge distribution , is obtained
for nuclei whose live times are longer than about 1 min.

Luminosity of e-RI Collision
80
1032
60
N

1030
40

1028

20

50

N

100

[cm 2/sj

Fig. 1. The luminosity for the head-on collision of electrons and unstable nuclei in DSR.

References
1) T. Katayama and N. Tokuda: Particle Accelerators, 21
99 (1987).

RIKEN Accel. Prog. Rep. 29 (1996)

An Undulator and the Photon Flux at MUSES
M. Wakasugi, N. Inabe , and T. Katayama
Double storage rings (DSR) are planned to be constructed as the experimental tool in the MUSES which
are proposed for the RI beam factory program. 1) It canstore not only an HI beam but also an electron beam.
We have proposed the isotope shift measurement inatomic transitions of highly charged ion beams using the DSR to obtain systematically the mean squarecharge radii of radioactive isotopes far from a stability line which are produced with a projectile fragment
separator (Big RIPS). The synchrotron radiation fromone of the DSR in which the electron beam is storedwith the energy of Ee = 0.3- 2.5 GeV, is used to excite
D1 and D2 transitions in a Li-like ion of a radioactive
isotope which is stored in the other.
An undulator is designed to be inserted in the electron storage ring as a source of the radiation to makeintense and narrow band X ray. The energy range ofthe X ray is from 30 to 2000 eV with the first harmonic radiation. The energy range was chosen to excite D1 and D2 transitions in Li-like ions with Z > 40.
The energy resolution of the X ray is required to be~Ex/Ex < 2 x 10- 4 in the case of U 89 + (EDI = 286eV) to resolve the isotope shift, and the photon flux ofmore than 10 12 photons/s is required. The lattice of
the DSR was also designed so as to make the emittanceof electron beam as low as possible,2) because the quality of the X ray from the undulator depends strongly
on the emittance of electron beam in the DSR.
Parameters of the electron beam with an energy of
Ee = 2.5 GeV in the DSR are shown in Table 1. There
are short straight sections with 6.5 m in length close
to the colliding section in the DSR for insertion of theundulator. 2) The values of the betatron function inboth x and y directions are about 5 m and they arenearly constant in this section. The natural emittance
Table 1. Parameters of the stored electron beam with
Ee = 2.5 GeV.
Max. beam energy (Ge V)
Max. beam current (A)Max. stored number of electron
Beam emittance (ex/Ey) (nmrad)
Energy spread (AEe /Ee)
Bunch length (em)RF voltage (MV)
RF frequency (MHz)
Revolution frequency (MHz)Harmonic number
N umber of bunch (typical)
Touschek lifetime (s)Synchrotron radiation
loss (keV /turn)2.5
0.5
2.7 x 10 12
8.54/25.5
6.84 x 10- 4
0.5
2.0
498.2
1.159
430
23
4.55 x 104
371.7

is made lower by adopting a double bend achromat
lattice. The momentum compaction factor Q and thedispersion TJ are nearly zero in this section. This meansthat a change of the envelope of the electron beam isquite small in the undurator. The size of the electron
beam is about 120 x 200 J.1m 2 •Parameters of the undulator designed here are shownin Table 2. The X ray energy has to be tunable continuously to make a high resolution isotope shift measurement . This is realized with the tunability of theK value by changing the pole gap with a step of lessthan 5 J.1m. The undulator should be of the in-vacuum
type because the pole gap is too narrow to insert avacuum chamber; the gap is changed from 1 to 3 cm
which corresponds to the K values of from 2.0 to 0.3.

E

Table 2. Parameters of the undulator.
Length (m)Length of one period (em)Number of periods
K value
Magnetic field at the pole tip (T)Photon energy at Ee = 1.0 GeV,
K = 1 (eV)Photon flux at Ee = 1.0 GeV, K = 1(photons/s mrad 2 0.1% b.w.)

6.0
3.0
200
0.3- 2.0
1.3

210.7
8.6 X 10 17

The calculated photon flux (photons/s mrad 2 0.1%b.w.) on the beam axis is shown in Fig. 1 for the casesof the electron beam energies of 1.0, 1.5, 2.0, and 2.5
Ge V. In this calculation the electron beam current istaken to be 500 rnA and the K value is fixed to unity.
The maximum X ray energy of 2000 eV required here
can be obtained with the smallest K value and the 2.5
19

~ '0
..0
18
?R. ,0
xci ,0 17:::J-N...... -0
C

0
0

ro '0

16

"-

+-'

E ,0 15~(/)

o..~ 10 14
C

0
0

'0

3

,0 12

+-'
~

13

0

500

1000

1500

2000

X ray energy (eV)Fig. 1. Calculated photon fluxes on the beam axis fromthe undulator.

257

GeV electron energy. The flux can be reached to about
10 18 photons/s mrad 2 0.1% b.w. at the electron energyof Ee = 1.0 GeV and K = 1. The photon flux ofabout 10 18 can be kept in the energy range of 100- 2000
eV by adjusting the K value and the electron energy.
The maximum photon flux is obtained at the electronenergy of 1.2 GeV with fixed K value.
The X ray monochromized with an X ray spectrometer is used for the isotope shift measurement. The
monochromization reduces the X ray yield to be 10%
and the transmission efficiency of the monochrometeris assumed to be 1.0%. Then the effective photon flux,
which has the required energy resolution for the isotope shift measurement, at the colliding point becomes258

about 10 12 photons/s if the spectrometer has an angular acceptance of 0.1 mrad. The required photon fluxof 10 12 photons/s is found to be satisfied from thiscalculation.
Energy loss of the electron due to the undulator isless than 2 keY at 0.5 GeV < Ee < 2.5 GeV and at
0.3 < K < 2.0. The tune shift of the electron beam is.6.Q < 0.1 in the same ranges of the electron energies
and K values. These give no serious problem to theelectron beam in the DSR.
References
1) T . Katayama: This report , p. 238.
2) N. Inabe et al.: This report, p. 248.

VI.

RADIATION MONITORINGRIKEN Accel. Prog. Rep. 29 (1996)

Leakage Radiation Measurements in the
Ring Cyclotron Facility
S. Fujita, N. Nakanishi, S. Nakajima, M. Watanabe,* H. Ohishi,*
Y. Uwamino, and T. T. Inamura
The measurements of leakage radiation were carriedout with five kinds of beams: 110, 113, and 135-MeV
proton , 135-MeV /nucleon 14N and lOa-MeV/nucleon
18 0. The beam intensities were about 200 pnA for protons, 20 pnA for 14N, and 10 pnA for 18 0. The beams
were stopped at an iron target in the beam distribution
corridor.
Leakage radiation of neutrons from the corridor wasmeasured with four neutron dose rate meters, TPS4518's (Aloka). The beam current at the target wasread with a current integrator (ORTEC 439) andrecorded with a personal computer. Figures l(a), (b),and (c) show the target point and positions where leakage radiation was measured. The positions, 1Fc andB2c, are on the first floor and 2nd basement floor justright upper and under the target point, respectively.
Leakage of neutrons was also detected at the several
points outside of the building. Results are summarizedin Table 1. Dose rates were normalized with respect
to the beam intensity of 1 pf-tA.

(a)

r
(b)

J

II~

GR

x WR

x GC

wc

IIx

WL

GL

(c)

Fig. 1. Partial layout of the RIKEN Ring Cyclotron facility where the leakage radiation measurement
was made. (a) Part of the 2nd basement floor; (b) Part of the 1st basement floor; (c) Part of the 1st
floor. The target point is denoted by a closed circle. Leakage-radiation-dose measuring points aredenoted by x.

Faculty of Science and Technology, Chuo University

259

Table 1. Dose rates of neutron leakage radiation from a target placed in the beam distribution
corridor. (see Figs. l(a),(b),(c)). The unit of energy is MeV jnucleon. The notations of lFa- GL stand for measured positions shown in Fig. 1. The unit of dose rate is (J.LSv jh)j(pJ.LA).
Measured date
Accelerated particle
EnergyPosition
IF a
IF c
IF b
E5 a
E5 c
E5 b
E4 a
E4 c
E4 b
B2 a
B2 c
B2 b
Out R
Out C
Out L
WR
WC
WL
GR
GC
GL

260

Feb. 11, '95
P
135
Dose rate
7.43E-02
5.95E-02
1.90E-02
2.44E+Ol
1.57E+Ol
5.43E+Ol
7.50E+00
4.14E+00
1.57E+00
1.93E+Ol
1.30E+0l
7.00E+00
l.B8E+Ol
2.37E+Ol
l.B5E+Ol
B.42E-Ol
B.56E-Ol
6.83E-Ol
4.3lE-Ol
4.92E-Ol
4.6lE-Ol

Mar. 1, '95

Mar. 15, '95

I4N7=t=I!:!08=t=

135
Dose rate
3.22E+00
1.56E+00
7.60E-Ol
3.09E+02
1.88E+02
2.0lE+02
1.25E+02
7.83E+Ol
2.68E+Ol
2.20E+02
2.09E+02
9.79E+0l
1.16E+03
1.5lE+03
1.12E+03
4.48E+Ol
4.85E+Ol
3.73E+Ol
2.2lE+Ol
3.0BE+Ol
2.53E+Ol

100
Dose rate
1.6lE+00
9.96E-Ol
1.02E+00
1.38E+02
1.60E+02
2.04E+02
5.70E+Ol
4.52E+Ol
3.21E+01
1.35E+02
1.33E+02
9.37E+0l
5.l4E+02
6.65E+02
5.l7E+02
2.09E+Ol
2.20E+Ol
2.11E+Ol
1.20E+Ol
1.16E+Ol
1.19E+Ol

Apr. 25, '~5P
113
Dose rate
4.96E-02
4.OlE-02
4.88E-02
1.67E+Ol
2.85E+Ol
6.07E+Ol
5.73E+00
4.38E+00
3.66E+00
1.OBE+Ol
9.40E+00
1.04E+Ol
4.B6E+00
6.13E+00
4.94E+00
3.45E-0l
3.54E-0l
3.34E-Ol
1.59E-Ol
2.08E-Ol
2.05E-Ol

June 28, '95
P
110
Dose rate
2.05E-02
1.26E-02
1.86E-02
1.95E+00
3.35E+00
1.7lE+Ol
2.32E+00
1.45E+00
4.2BE-Ol
7.00E+00
4.94E+00
4.l7E+00
3.88E+00
4.9BE+00
3.BOE+00
1.64E-Ol
1.63E-Ol
1.47E-Ol
B.88E-02
4.66E-Ol
1.07E-OlRIKEN Accel. Prog. Rep. 29 (1996)

Dose Rates Due to Residual Activities in
the Ring Cyclotron Facility
S. Fujita, M. Watanabe,* H. Ohishi,* N. Nakanishi, Y. Uwamino, and T. T. Inamura
Dose rates due to residual radioactivities were measured at various points in the Ring Cyclotron facility.
In the following we describe significant dose rates observed in the measurements.
The routine overhaul started just after the last beamtime of the spring term, which was carried out with an
12C6+ beam of 135 MeV/nucleon in the E6 experimental vault from Aug. 3 to 4. The dose rates in the
Ring Cyclotron and the injector AVF cyclotron were
measured on Aug. 23 and 24, during the overhaul period. The measured data of the Ring Cyclotron are
shown in Fig. 1. Dose rates in the AVF cyclotron were

denote the places where the dose rates exceeded 50
j..LSV /h. Table 1 summarizes the observed dose rates
with the dates on which the measurements were performed. The maximum dose rate was found to be
11000 J,LSv /h at the target chamber, denoted by the
point P in Fig. 3.

Beam

DOSE VNIT

pSv/hFig. 2. Dose rates measured in the injector AVF cyclotron.
They are given in units of p,Sv /h; * indicates the datameasured on May 29.

DOSE UNIT

~Sv/h

Beam

t

Fig.
1. Detection points around the RIKEN Ring
Cyclotron: EDC , the electrostatic deflection channel;
MDC1 , the magnetic deflection channell; MDC2 , themagnetic deflection channel 2; MDP1 , the main differential probe 1; MDP2 , the main differential probe 2;
MDP3, the main differential probe 3. Indicated numerals are dose rates in units of p,Sv /h.

also measured when its acceleration chamber was
opened on May 29 because of a vacuum trouble. All
the data are shown in Fig. 2.
In the period from Oct. 1, 1994 to Sept. 30, 1995,
dose rates were measured along the beam lines afteralmost every beam time. The points a-t in Fig. 3

Fig. 3. Layout of the RIKEN Ring Cyclotron facility.
Detection points of residual activities along the beamlines are denoted by a-to

Faculty of Science and Technology, Chuo University

26l

Table 1. Summary of the dose rates measured along the beam lines with ionization-chamber survey meters. The points a-t indicate the detection points
shown in Fig. 3.
Detection
point

a
b
c

d
e
f
g

h

j

262

Measured
dose rate(ILSv jh)
1200
300
400
230
70
90
50
750
650
300

Date

Detectionpoint

May 29, '95
Apr. 3, '95
Oct. 31, '94
Aug. 11, '95
Oct. 31, '94
Aug. 11, '95
May 2, '95
July 11, '95
Oct. 26, '94
Oct. 26, '94

k
I
III

n
0

p
q
r
s
t

Measured
dose rate(ILSV jh)
2500
300
140
50
60
11000
200
800
750
70

-Date

July 28, '95
Oct. 26, '94
Aug. 9, '95
June 7, '95
Oct. 26, '94
Oct. 26, '94
Mar. 23, '95
June 12, '95
June 12, '95
July 21, '95

RIKEN Accel. Prog. Rep. 29 (1996)

Routine Works for Radiation Safety in the Ring Cyclotron Facility
S. Fujita, N. Nakanishi, M. Watanabe,* H. Ohishi, * Y. Uwamino, and T. T . Inamura
The radiation safety control system has worked
steadily this year, so as to enable us to make radiation monitoring continuously and automatically.
Figures l(a), (b), and (c) show the trend graphs of..s::: [0

;;
CIi

0

{/)

-1

::t [0

§ 10
....

'5
0)
Z

[0

-2
-3

10

date (1995)(a)neutron-radiation level during several days around thetime when the maximum levels of this year wererecorded at the three positions: E4 room in the controlled area, the computer room at the boundary of
the controlled area, and outside at the boundary of the
RIKEN site. Those radiation levels, however, are farless than the required safety limits for the controlledarea (1 mSv /week), for the boundary of the controlledarea (0.3 mSv /week), and for the boundary of the site
(50 p,Sv /year).
In this summer, all alarm lamps in each room inside the controlled area were changed to new ones,
which show the same information as the radiation levelindicators 1 ) at the entrance of each room. Figure 2
shows the photograph of new lamps with neutron and,-ray detectors.

..c:

~

:::1. 10

-2

{/)

t::

o
....
"'5
0)

-3

10

Z

(b)

..c:

ca>
..

-2

~ 10

g

z~

Fig. 1. Daily variation in the radiation level detected at
the RIKEN Ring Cyclotron facility. Detectors are (a)a BF3 counter in the experimental vault E4 of the controlled area, (b) a 3He counter in the computer room,boundary of the controlled area, and (c) a 3He counterat the boundary of the site.

Fig. 2. The photograph of new lamps with neutron and,-ray detectors.

We installed a new hand-foot-cloth monitor in frontof the AVF cyclotron vault, in order to prevent contamination around the cyclotron from spreading to otherplaces in the controlled area.
References
1) I. Sakamoto, S. Fujita, T. Wada, and H. Takebe:
RIKEN Accel. Prog. Rep., 20, 206 (1986) .

Faculty of Science and Technology, Chuo University

263

VII. LIST OF PUBLICATIONS
1.

Accelerator
physics

development

andaccelerator

T. Nakagawa, T. Kageyama, M. Kase, A. Goto, andY. Yano: "Effect of Plasma-Cathode Method on
Production of Highly Charged Ions from Oxide in
RIKEN 10-GHz Electron-Cyclotron-Resonance Ion
Source", Jpn. J. Appl. Phys., 34, 2463 (1995).
O. Kamigaito, A. Goto, Y. Miyazawa, T. Chiba, M.
Hemmi, M. Kase, S. Kohara, and Y. Yano: "Improvement of Frequency Variability of the FoldedCoaxial Radio-Frequency Quadrupole Linac by Installing a Detachable Stem in Its Resonator", ibid.,
pp. 5799- 5800.
Y. Batygin, V. Kushin, and S. Plotnikov: "Uniform
Target Irradiation by Circular Beam Sweeping",
Nucl. Instrum. Methods Phys. Res., A363, 128-130(1995).
N. Nakanishi, T. Shikata, S. Fujita, and T. Kosako:"Calculated Shielding Characteristics of Eight Materials for Neutrons and Secondary Photons Produced
by Monoenergetic Source Neutrons with Energies
Less Than 400 MeV", Nucl. Technol., 112, 132- 141(1995).
Y. Batygin: "Nonlinear Potential Distribution forHigh Current Beam Transport without Emittance
Growth" , Proc. 17th Int. Linac Conf. (LINAC 94),
Tsukuba, K. Takara et al. (eds.), Vol. 1, pp. 487- 489(1994).
Y. Batygin: "Density Uniforming of Large Momentum
Spread Beam", ibid., pp. 490- 492.
O. Kamigaito, A. Goto, Y. Miyazawa, T. Chiba, M.
Hemmi, S. Kohara, M. Kase, and Y. Yano: "Designof a New Type of Variable-Frequency RFQ Linac
with a Folded-Coaxial Resonator", ibid., pp. 701703.
M. Niimura, T. Kageyama, T. Nakagawa, A. Goto,
and Y. Yano: "Physics for ECRIS Beam-Current
Upgrading Technologies Such as Electron Beam Injection, Wall Coating, and Gas Mixing", Proc. 12th
Int. Workshop on ECR Ion Sources, M. Sekiguchi
and T. Nakagawa (eds.), No. INS-J-182 , pp. 141- 147(1995).
M. Niimura, H. Amemiya, A. Goto, and Y. Yano:"Averaged Excitation Rate Coefficient Calculationof HeI Up to T e = 1000 eV and Plasma Potential
Measurement Up to ECR-Heated Ellipsoid", ibid.,
pp. 307- 311.
T. Nakagawa, T. Kageyama, M. Kase, A. Goto, andY. Yano: "Production of Highly Charged Ions from
Oxide in RIKEN 10 GHz ECRIS", ibid., pp. 314316.
Y. Batygin, A. Goto, and Y. Yano: "Nonlinear Effectof Einzel Lens to the Beam Extracted from ECR
Source", ibid., pp. 317- 320.

Y. Batygin: "Conservation of High Current Beam
Emittance in Nonlinear Focusing Field", Proc. Int.
Workshop on Particle Dynamics in Accelerators, S.
Machida and K. Hirata (eds.), KEK Proc., No. 95-7,
pp. 88-96 (1995).
O. Kamigaito, A. Goto, Y. Miyazawa, T. Chiba, M.
Hemmi, S. Kohara, M. Kase, Y. Batygin, and Y.
Yano: "Development of a Variable-Frequency RFQ
Linac for the RILAC", Proc. 20th Linear Accelerator
Meet. in Japan, Osaka, pp. 82-85 (1995).
T. Kubo, H. Okuno, K. Ikegami, T. Kawaguchi, T.
Tominaka, T. Mitsumoto, S. Fujishima, A. Goto, andY. Yano: "RI-beam Factory Project (I) - Superconducting Ring Cyclotron -", Proc. 54th Meet. on
Cryogenics and Superconductivity, Nov., Akita, p.
62 (1995).
T. Kawaguchi, T. Mitsumoto, T. Kubo, T. Tominaka,
H. Okuno, Y. Tanaka, S. Fujishima, K. 1kegami, A.
Goto, and Y. Yano: "RI Beam Factory Project (II)- Superconducting Sector Magnet -", ibid., p. 63.
T. Tominaka, H. Okuno, Y. Tanaka, T. Kubo, T. Mitsumoto, T. Kawaguchi, S. Fujishima, K. Ikegami, A.
Goto, and Y. Yano: "RI Beam Factory Project (III)- Beam Injection and Extraction Systems - ", ibid.,p.64.
M. Kase, N. Inabe, A. Goto, T. Kageyama, 1.
Yokoyama, M. Nagase, S. Kohara, T. Nakagawa,K. Ikegami, O. Kamigaito, J. Fujita, and Y. Yano:"The Operation of RIKEN Ring Cyclotron", Proc.
10th Symp. on Accelerator Science and Technology,
JAERI ConL, Oct., 1995, Hitachinaka, pp. 23-25(1995).
T. Mitsumoto, A. Goto, T. Kawaguchi, Y. Tanaka, T.
Kubo, H. Okuno, T. Tominaka, S. Fujishima, andY. Yano: "Design Study of Sector Magnet for the
RIKEN Superconducting Ring Cyclotron (I)", ibid.,
pp. 124- 126.
T. Kawaguchi, T. Kubo, T. Mitsumoto, T. Tominaka,
S. Fujishima, H. Okuno, Y. Tanaka, K. 1kegami, A.
Goto, and Y. Yano: "Design Study of Sector Magnet for the RIKEN Superconducting Ring Cyclotron(II)", ibid., pp. 127- 129.
N. Inabe, M. Kase, I. Yokoyama, A. Goto, and Y.
Yano: "Development of a Single-Bunch Selector for
RIKEN Ring Cyclotron", ibid., pp. 165- 167.
A. Goto, Y. Miyazawa, M. Hemmi, O. Kamigaito, T.
Nakagawa, M. Kase, T. Chiba, N. Inabe, S. Kohara,
T. Kageyama, Y. Batygin, and Y. Yano: "Construction of a New Pre-injector System for the RILAC",
ibid., pp. 188-190.
T. Nakagawa, Y. Miyazawa, M. Hemmi, T. Chiba, N.
Inabe, M. Kase, T. Kageyama, O. Kamigaito, E.
Ikezawa, A. Goto, and Y. Yano: "Development of
RIKEN 18 GHz ECRIS", ibid., pp. 224- 226.
O. Kamigaito, A. Goto, Y. Miyazawa, T. Chiba, M.
Hemmi, S. Kohara, M. Kase, Y. Batygin, and Y.
265

Yano: "Development of a Variable-Frequency RFQ
Linac for the RILAC", ibid. , pp. 236- 238.
M. Takanaka and T. Katayama: "Beam Current Limitations Due to Single-Beam Collective Effects in
the Ion Storage Ring of RIKEN RI Beam Factory
Project", ibid. , pp. 318- 320.
Y . Batygin, A. Goto, and Y. Yano: "Hollow Beam Formation in the Extraction Region of ECRIS" , ibid. ,pp. 353- 355.
Y. Batygin and T. Katayama: "Study of Incoherent
Beam-Beam Effects at Radioactive Isotope Beam
Factory", ibid. , pp. 356-358.
Y. Batygin, A. Goto , O. Kamigaito, and Y . Yano:"Effect of Field Variation on Beam Parameters in
RIKEN RFQ Linac", ibid. , pp. 359- 36l.
N. Nakanishi, T. Shikata, S. Fujita, and T. Kosako:"Comparison of Calculated Shielding Effects for 8
Materials", ibid. , pp. 362-364.
Y. Yano, A. Goto, T. Katayama, and RIBF Group:"RIKEN RI Beam Factory Project", ibid. , pp. 457459.
M. Niimura, T. Nakagawa, A. Goto, and Y. Yano:"Next-Step ECRIS and 2 m Length 4.52 GeV Advanced Accelerator: Novel Extraction of Trapped
Ions and their Acceleration-Final Focusing by Nonneutral and Neutral Plasmas", ibid. , pp. 466- 468.
Y. Yano: "RIKEN Accelerator Research Facility(RARF) , Its New Project 'RI Beam Factory', andOther Major Heavy-Ion Accelerator Facilities inJapan", Proc. Simposio Nipo-Brasileiro de Ciencia
e Technologia, Brazil, pp. 194- 202 (1995).
2.

Nuclear physics and nuclear instrumentation

S. Ishida, S. Fujita, Y. Hara, K. Hatanaka, T.
Ichihara, K. Katoh, T. Niizeki, H. Okamura, H.
Otsu, H. Sakai, N. Sakamoto, Y. Satou, T. Uesaka,
T . Wakasa, and T. Yamashita: "Construction of
the Deuteron POLarimeter DPOL at RIKEN", AlP
Conf. Proc. , 343, 182- 186 (1995).
K. Sumiyoshi, H. Suzuki, and H. Toki: "Influence of
the Symmetry Energy on the Birth of Neutron Stars
and Supernova Neutrinos", Astron. Astrophys. , 303,475- 482 (1995).
Y. Mochizuki and T. Izuyama: "Self-Trapping of Superfluid Vortices and the Origin of Pulsar Glitches" ,Astrophys. J. , 440 , 263- 269 (1995).
A. A. Korsheninnikov, M. V. Zhukov, M. Smedberg,
and T. Kobayashi: "Neutron Momentum Distributions from Fragmentation of the Exotic Nucleus
8He", Europhys. Lett. , 29, 359- 364 (1995).
S. A. Goncharov and A. A. Korsheninnikov: "Theoretical Analysis of Elastic and Inelastic Scattering
8He + p at E = 72 MeV lu", ibid. , 30, 13- 18 (1995).
T. Kohno, A. A. Gusev, 1. M. Martin, and G. 1.
Pugacheva: "The Trapped He Flux Dynamics Observed on the OHZORA Satellite during 1984-1987",
Geophys. Res. Lett. , 22 , 877- 880 (1995).

266

M. Kurokawa, T. Motobayashi, K . Ieki, S. Shimoura,
H. Murakami, Y. Ikeda, S. Moriya, Y. Yanagisawa,and T. Nomura: "Radiation Damage Factor for IonImplanted Silicon Detectors Irradiated with Heavy
Ions", IEEE Trans. Nut l. Sci. , 42 , 163- 166 (1995).
S. Date, K. Kumagai , O. Miyamura, H. Sumiyoshi,
and X.-Z. Zhang: "A Study of Collision Frequency
and Part icle Density in Ultrarelativistic Nuclear Collisions by an Event Generator URASIMA", J. Phys.
Soc. Jpn. , 64, 766- 776 (1995).
K. Kitao: "A = 118 Update", Nucl. Data Sheets, 75 ,99- 198 (1995).
N. Nakao, T. Nakamura, M. Baba, Y. Uwamino, N.
Nakanishi , H. Nakashima, and Sh. Tanaka: "Measurements of Response Function of Organic Liquid
Scintillator for Neutron Energy Range Up to 135
MeV", Nucl. Instrum. M ethods Phys. Res. , A362 ,454- 465 (1995).
A. Warczak, and 13 others including T. Suzuki: "Radiative Double Electron Capture in Heavy-Ion Atom
Collisions", ibid. , B98, 303- 306 (1995).
T. Ichihara, M. Ishihara, H. Ohnuma, T. Niizeki,
T. Yamamoto , K. Kat oh, T. Yamashita, Y. Hara,
Y. Fuchi, S. Kubono, M. H. Tanaka, H. Okamura,
S. Ishida, T. Uesaka, and Y. Satou: "Spin-Flipand Non-Spin-Flip Isovector Excitations Observedin the (12c ,12N) Reactions at EI A = 135 MeV andthe (13C ,13N) Reactions at EI A = 100 MeV", Nucl.
Phys., A583 , 109c- 114c (1995).
T. Nakagawa, K. Yuasa-Nakagawa, K. Furutaka, K.
Matsuda, K. Yoshida, Y. Futami, T. Mizota, Y.
Honjo, S. Tomita, S. M. Lee, J. Kasagi , and W.
Q. Shen: "Study of Pre-scission Evaporation for
84 Kr + 27 Al at 10.6 MeV l u Using 37r-Phoswich Detector System", ibid. , 149c- 152c.
J. Chiba, D. Ashery, H. Ito, K. Kimura, Yu. T. Kiselev,
S. Kouda, K. Miyano, T. Murakami, T. Nagae, Y.
Nakai, M. Nomachi, H. Ochiishi, S. Sawada, M.
Sekimoto, Y. Sugaya, T. Suzuki , K. H. Tanaka,
M. K. Vlasov, Y. Yamanoi, K. Yasuda, and Y.
Yoshimura: "Subthreshold Antiproton Productions
in pA, dA , and o:.A React ions" , ibid. , pp. 633c- 636c.
S. Neumajer and 27 ot hers including T. Suzuki:"Study of Nucleon Density Distribution of 6He and
8He by Proton Elastic Scattering in Iverse Kinematics", ibid. , pp. 799c- 802c.
M. V. Zhukov, A. A. Korsheninnikov, M. H. Smedberg,
and T. Kobayashi: "Particle Momentum Distributions for 8He in 0:. + 4n Model", ibid. , pp. 803c- 806c.
A. Ozawa, 1. Tanihata, T. Kobayashi, D. Hirata, O.
Yam akawa , K. Ornata, N . Takahashi, T. Shimoda,
K. Sugimoto, D. Olson, W. Christie, and H. Wieman:"Interaction Cross Sections and Radii of 11C and 12N
and Effective Deformation Parameters in Light Mirror Nuclei", ibid. , pp. 807c-810c.
L. V. Chulkov, C. A. Bertulani, and A. A.
Korsheninnikov: "Proton Scattering by 8He andNeutron Halo Effects" , ibid., A587, 291- 300 (1995).

A. A. Korsheninnikov, D. V. Aleksandrov , N. Aoi,
Y. Doki , N. Inabe, M. Fujimaki, T. Kobayashi,
H. Kumagai, C.-B. Moon, E. Yu. Nikolskii, M. M.
Obuti, A. A. Ogloblin, A. Ozawa, S. Shimoura, T.
Suzuki, I. Tanihata, Y. Watanabe, M. Yanokura, andK. Yoshida: "Experimental Studies of Light Neutron
Rich Nuclei", ibid., A588, 23c- 28c (1995).
Y. Ogawa, Y. Suzuki, and K. Yabana: "Transverse
Momentum Distributions of a 9Li Fragment in the(11 Li, 9Li) Reaction and Neutron Correlations",
ibid., pp. 77c-80c.
A. Yoshida, N. Aoi, T . Fukuda, M. Hirai, M. Ishihara,
H. Kobimtta, Y. Mizoi, L. Mueller , Y. Nagashima,
J. Nakano, T. Nomura, Y. H. Pu, F. Scarlassala, C.
Signorini, and Y. Watanabe: "Measurement of Fusion Cross Section with Neutron Halo Nuclei", ibid.,
pp. 109c- 112c.
W. von Oertzen, H. G. Bohlen, B. Gebauer, M. vonLucke-Petsch, A. N. Ostrovski, Ch. Seyfert, Th.
Stolla, M. Wilpert, Th. Wilpert, D. V. Alexandrov,
A. A. Korsheninnikov, I. Mukha, A. A. Ogloblin, R.
Kalpakchieva, Y. E. Penionzhkevich, S. Piskor, S.
M. Grimes, and T. N. Massey: "Nuclear Sructure
Studies of Very Neutron-Rich Isotopes of 7- 10 He,
9-11 Li, and 12- 14 Be via Two-Body Reactions", ibid.,
pp. 129c- 134c.
K. Asahi , H. Ueno, H. Izumi, H. Okuno , K. Nagata, H.
Ogawa, Y. Hori, H. Sato, K. Mochinaga, M. Adachi,
A. Yoshida, G. Liu, N. Aoi, T. Kubo, M. Ishihara,
W.-D. Schmidt-Ott , T. Shimoda, H. Miyatake, S.
Mitsuoka, and N. Takahashi: "Electromagnetic Moments of Unstable Nuclei Studied with Polarized
Projectile Fragments", ibid., pp. 135c-140c.
M. Tohyama: "E1 and E2 Giant Resonance in 220",
ibid., pp. 141c- 146c.
K. Matsuta, M. Fukuda, M. Tanigaki, T. Minamisono,
Y. Nojiri, M. Mihara, T. Onishi, T. Yamaguchi,
A. Harada, M. Sasaki, T. Miyake, S. Fukuda, K.
Yoshida, A. Ozawa, T. Kobayashi, I. Tanihata, J. R.
Alonso, G. F. Krebs, and T. J. M. Symons: "Magnetic Moment of Proton Drip-Line Nucleus 9C",
ibid., pp. 153c- 156c.
Y. Gono, T. Morikawa, T. Kishida, K. Moita, A.
Odahara, E. Ideguchi , T. Murakami , M. Oshima, M.
Sugawara, H. Kusakari, H. Kumagai, H. Tsuchida,
M. Ogawa, M. Kidera, M. Shibata, K. Miyazaki, S.
Mitarai, Y. H. Zhang, A. Ferragut, G. H. Liu, Y.
Hatsukawa, J. C. Kim, S. A. Shin, and M. Ishihara:"Gamma-Ray Spectroscopy with High-Spin Isomer
Beam", ibid., pp. 241c- 246c.
H. Toki, D. Hirata, Y. Sugahara, K. Sumiyoshi, and
I. Tanihata: "Relativistic Many Body Approach for
Unstable Nuclei and Supernova", ibid., pp. 357c364c.
A. Ozawa, G. Raimann, R. N. Botd, F. R.
Chloupek, M. Fujimaki, K. Kimura, H. Kitagawa,
T. Kobayashi, J. J. Kolata, S. Kubono, I. Tanihata,
Y. Watanabe, and K. Yoshida: "Study of }3-Delayed

Neutron Emission of 19C", ibid., A592, 244- 256(1995).
K. Sumiyoshi, K. Oyamatsu, and H. Toki: "NeutronStar Profiles in Relativistic Brueckner-Hartree-Fock
Theory", ibid., A595 , 327-345 (1995).
T. Kandler, and 16 others including T. Suzuki: "Transition Selective Investigation of the Resonant Transfer and Excitation in U 90 + ~ C Collisions", Phys.
Lett. , A204, 274- 280 (1995).
X. Gu, R. N. Boyd, M. M. Farrell, J. D. Kalen, C.
A. Mitchell, J. J. Kolata, M. Belbot, K. Lamkin, K.
Ashktrab , F. D. Becchetti, J. Brown, D. Roberts, K.
Kimura, I. Tanihata, K. Yoshida, and M. S. Islam:"The 8 Li (Q ,n) 11 B Reaction and Primordial N ucleosynthesis", ibid., B343, 31- 35 (1995).
A. A. Korsheninnikov, E. Yu. Nikolskii, T. Kobayashi,
D. V. Aleksandrov, M. Fujimaki, H. Kumagai, A. A.
Ogloblin, A. Ozawa, I. Tanihata, Y. Watanabe, andK. Yoshida: "Spectroscopy of 12Be and 13Be Using
12Be Radioactive Beam", ibid., pp. 53- 58.
J. A. Casado and S. Date: "On the Systematic Behavior of the Chaoticity Parameter in HBT Analyses",
ibid., B344, 441- 446 (1995).
T. Motobayashi, Y. Ikeda, Y. Ando, K. Ieki, M.
Inoue, N. Iwasa, T. Kikuchi, M. Kurokawa, S.
Moriya, S. Ogawa, H. Murakami, S. Shimoura,
Y. Yanagisawa, T. Nakamura, Y. Watanabe, M.
Ishihara, T. Teranishi, H. Okuno, and R. F. Casten:"Large Deformation of the Very Neutron-Rich Nucleus 32Mg from Intermediate-Energy Coulomb Excitation", ibid., B346, 9-14 (1995).
S. Shimoura, T. Nakamura, M. Ishihara, N. Inabe, T.
Kobayashi , T. Kubo, R. H. Siemssen, I. Tanihata,
and Y. Watanabe: "Coulomb Dissociation Reaction
and Correlations of Two Halo Neutrons in 11 Li",ibid., B348, 29- 34 (1995).
T. Morikawa, Y. Gono, K. Morita, T. Kishida, T.
Murakami, E. Ideguchi, H. Kumagai, G. H. Liu, A.
Ferragut, A. Yoshida, Y. H. Zhang, M. Oshima, M.
Sugawara, H. Kusakari, M. Ogawa, M. Nakajima,
H. Tsuchida, S. Mitarai, A. Odahara, M. Kidera,
M. Shibata, J. C. Kim, S. J. Chae, Y. Hatsukawa,and M. Ishihara: "Coulomb Excitation of 174Hf KIsomer. ')'-Ray Spectroscopy with High-Spin Isomer
Beam", ibid., B350 , 169-172 (1995).
K. Yuasa-Nakagawa, T. Nakagawa, K. Furutaka, K.
Matsuda, Y. Futami, K. Yoshida, J. Kasagi, S. M.
Lee, T. Suomijarvi, W. Q. Shen, and T. Matsuse:"Entrance Channel Effect on the Pre-scission Timeof Binary Decay for the Medium Mass Nuclei (Massrv110)", ibid., B351, 77-81 (1995).
Ch. O. Bacri, B. Borderire, J. L. Charvet, D. Cussol, R. Dayras, O. Lopetz, A. Ouatizerga, M. F.
Rivet, G. Auger, A. Bemkirance, J. Benlliure, B.
Berthier, R. Bougault, R. Brou, P. Box, Y. Cassagnou, A. Chibihi, J. Colin, E. De Phillippo, A.
Demeyer, D. Durand, P. Ecomard, P. Eudes, A.
Genoux-Lubain, D. Gourio, D. Guinet , L. Lakehal267

Ayat, P. Lautesse, L. J. Laville, L. Leberton, C.
Lebrun, J. F. Lecolley, A. LeFvre, R. Legrain, M.
Louvel, M. Mahi, M. Marie, V. Metivier , L. Napas , T. Nakagawa, M. Prolog, J. Peter, E. Plagnol,
E. Pollacco, A. Rahmani, R. Regimbart , T. Reposeur, E. Rosato, F. Saint-Laurent, M. Sualli, J. C.
Steckmeyer, B. Tamain, L. Tassan-Got , E. Vient , C.
Volant , J. P. Wieleczko, A. Wieloch, and K. YuasaNakagawa: "Onset of Vaporization for Ar + Ni Systern", ibid. , B353, 27- 31 (1995).
H. Okuno, K. Asahi, H. Ueno, H. Izumi, H. Sato,
M. Adachi, T. Nakamura, T. Kubo, N. Inabe, A.
Yoshida, N. Fukunishi , T. Shimoda, H. Miyatake,N. Takahashi , W.-D. Schmidt-Ott, and M. Ishihara:"Measurement of the Magnetic Moments of 14B and
15B Using Projectile Fragmentation Spin Polarization", ibid. , B354, 41- 45 (1995).
T. Horibata, M. Oi, and N. Onishi: "Signature Splitting of Tilted-Axis Rotational States", ibid. , B355,
433- 438 (1995).
T. Suzuki, T. Otsuka, and A. Muta: "Magnetic Moment of 11 Be", ibid., B364, 69-74 (1995).
W. G. Jin, M. Wakasugi, T. T . Inamura, T. Murayama, T. Wakui, H. Katsuragawa, T. Ariga, T.
Ishizuka, and I. Sugai: "Laser-rf Double-Resonance
Spectroscopy of 177, 179 Hf" , Phys. Rev. A , 52 , 157164 (1995).
A. Ono and H. Horiuchi: "Flow of Nucleons and Fragments in 40 Ar + 27 Al Collisions Studied with Antisymmetrized Molecular Dynamics", Phys. Rev. C,
51 , 299- 309 (1995).
K. Sugawara-Tanabe, A. Arima, and N. Yoshida:"Resurrection of the L-S Coupling Scheme in Superdeformation", ibid. , pp. 1809- 1818.
E. Lienard, D. Baye, Th. Delbar , P. Descouvemont,
P. Duhamel, W. Galster, M. Kurokawa, P. Leleux,
I. Licot , P. Lipnik, C. Michotte, T. Motobayashi, A.
Ninane , J. Vanhorenbeeck, and J. Vervier: "Comparative Experimental Study of the Mirror 13N + 12C
and 13C + 12C Elastic Scatterings", ibid. , 52 , 775783 (1995).
K. Varga and Y. Suzuki: "Precise Solution of FewBody Problems with Stochastic Variational Method
on Correlated Gaussian Basis", ibid. , pp. 2885- 2905.
A. Mengoni , T. Otsuka, and M. Ishihara: "Direct
Radiative Capture of Jr Wave Neutrons", ibid., pp.
R2334- R2338.
R. A. Kryger, A. Azhari, M. Hellstrom, J. H. Kelley,
T . Kubo, R. Pfaff, E. Ramakrishnau, B. M. Sherrill , M. Toennessen, and S. Yokoyama: "Two-Proton
Emission from the Ground State of 12 0 ", Phys. Rev.
Lett. , 74, 860- 863 (1995).
T. Suzuki, H . Geissel, O. Bochkarev, L. Chulkov, M.
Golovkov, D. Hirata, H. Irnich, Z. Janas, H. Keller,
T. Kobayashi, G. Kraus, G. Miinzenberg, S. Neumaier , F. Nickel, A. Ozawa, A. Piechaczeck, E.
Roeckl, W. Schwab, K. Suemmerer, K. Yoshida, and
1. Tanihata: "Neutron Skin of Na Isotopes Stud268

ied via Their Interaction Cross Sections", ibid. , 75,
3241- 3244 (1995).
H. Irnich and 18 others including T. Suzuki: "Half-Life
Measurements of Bare, Mass-Resolved Isomers in a
Storage-Cooler Ring" , ibid. , pp. 4182- 4186.
T. Nakagawa, K. Yuasa-Nakagawa, Y. Futami, K .
Furutaka, K. Matsuda, K. Yoshida, T. Mizota, Y.
Honjo, S. Tomita, T. Suomijarvi, W. Q. Shen, J.
Kasagi , T. Matsuse, and S. M. Lee: "Pre- and Postscission Charged Particle Multiplicity in Binary Decay Process for Medium Mass Nuclei" , Proc. 3rd
IN2P3-RIKEN Symp. on Heavy Ion Collisions, T.
Motobayashi et al. (eds.) , World Scientific, Singapore, pp. 139- 147 (1995).
K. Furutaka, J. Kasagi, K. Yoshida, A. Yajima, Y.
Akeboshi , K. Matsuda, T. Murakami, T. Nakagawa,K. Yuasa-Nakagawa, Y. Futami, G. Bizard, and A.
Galonsky: "Excitation Energy and Temperature of
Hot Nuclei Produced in Incomplete Fusion Reactions", ibid. , pp. 180-188.
A. Ono and H. Horiuchi: "Flow of Nucleons and Fragments Studied with AMD", ibid. , pp. 219- 228.
S. Shimoura: "Nuclear Responses of Neutron DripLine Nuclei" , ibid., pp. 259- 268.
H. Kurasawa and T. Suzuki: "Macroscopic Model of
Giant Resonance States in N eutron-Rich Nuclei",
ibid. , pp. 269-282.
H. Kurasawa and T. Suzuki: "Quasielastic Electron
Scattering", Proc. Korea-Japan Joint Symp. on Recent Development of Nuclear Study Using Electron
and Photon Beams, II-Tong Cheon (ed.) , Global
Publications Services, Singapore, pp. 39- 46 (1995).
T. Wada: "Dissipative Dynamics of Nuclear Fission", Proc. Tours Symp. on Nuclear Physics II , H.
Utsunomiya et al. (eds. ), World Scientific, Singapore,pp. 470- 479 (1995).
A. Mengoni , T. Otsuka, and M. Ishihara: "Halo Structure of Nuclear Excited States and the Neutron Radiative Capture Process", Proc. Workshop on Experimental Perspectives with Radioact ive Nuclear
Beams, Padova, 14- 17 Nov. , 1994, C. Signorini (ed.),pp. 175- 185 (1995).
M. Tohyama: "Correlated Ground State and E2 Giant Resonance Built on It", Prog. Th eor. Phys. , 94 ,L147- L150 (1995).
S. Takagi , T. Nakamura, T. Kohno, and F. Makino:"Flux Distribution and Modulation of Charged Particles in the Radiation Belt Observed with AKEBONO", Rep. Institut e of Space and A stronautical
Science, 80, 1- 24 (1995).
T. Kohno, H. Kato, and K. Nagata: "Anomalous andSolar Cosmic Ray Observations with the First Brazilian Scient ific Microsat ellite", RIKEN Rev. , No. 10,
pp. 33- 34 (1995).
H. Kurasawa and T. Suzuki: "Effects of AntinucleonDegrees of Freedom on Quasielastic Electron Scattering", Soryusiron K enkyu (in Japanese) , 91 , c61- c65(1995).

W. Schwab 'a nd 16 others including T. Suzuki: "Observation of a Proton Halo in 8B", z.. Phys. , A350,
283- 284 (1995).
K. Morita, Y. H. Pu, J. Feng, M. G. Hies, K. O. Lee,A. Yoshida, S. C. Jeong, S. Kubono, T. Nomura, Y.
Tagaya, M. Wada, M. Kurokawa, T. Motobayashi,
H. Ogawa, T. Uchibori, K . Sueki, T. Ishizuka, K.
Uchiyama, Y. Fujita, H. Miyatake, T. Shimoda, T.
Shinozuka, H . Kudo, Y. Nagai, and S. A. Shin: "Newa-decaying Neutron Deficient Isotopes 197Rn and2ooFr", ibid., A352, 7-8 (1995).

3.

Atomic and solid-state physics

N. Toshima and J. Eichler: . "Relativistic Generalizations of Distorted-Wave Capture Theories", Comm.
Atom. Mol. Phys., 31 , 109- 122 (1995).
K. Kumagai, K. Kawano, I. Watanabe, K. Nishiyama,
and K. Nagamine: "p'sR and NMR Investigations
on Electronic and Magnetic State around x = 0.12
in La2-xBaxCU04 and La2-xSrxCu04" , Hyperfine
Interact. , 86, 473- 480 (1994).
I. Watanabe, K. Nishiyama, K. Nagamine, K. Kawano,and K . Kumagai: "Observation of Magnetic Order of
Cu-Moment around x = 0.12 in La2-xBaxCU04 andLa2-xSrxCu04 by jL+SR", ibid., pp. 603- 608.
M. Sataka, M. Imai, Y. Yamazaki, K. Komaki , K.
Kawatsura, Y. Kanai, K. Tawara, D. R. Schultz,
and C. O. Reinhold: "Projectile Charge State Dependence of Binary Electron Production for 1 Me V
U~l Au q + (q = 12 - 37) Ion Impact on He", J. Phys.
B: At. Mol. Opt. Phys. , 27, L171-L177 (1994).
L. P. Presnyakov, H. Tawara, I. Yu. Tolstikhina, andD. B. Uskov: "Double Ionization of Atomic Helium
under Heavy Ion Impact", ibid., 28 , 785- 793 (1995).
B. D. DePaola, Y. Kanai, P. Richard, Y. Nakai, T.
Kambara, T. M. Kojima, and Y. Awaya: "Binary
Encounter Electron Production at Relativistic Velocities", ibid. , pp. 4283- 4290.
T. Kambara, J. Z. Tang, Y. Awaya, B. D. DePaola, o. Jagutzki, Y. Kanai, M. Kimura, T. M.
Kojima, V . Mergel, Y. Nakai, H. Schmidt-Bocking,and I. Shimamura: "Three-Dimensional Recoil-Ion
Momentum Analyses in 8.7l\!IeV 0 7+ -He Collisions",
ibid., pp. 4593- 4606.
M. Hacke and E. Vagi: "Annealing Behaviour of Kr. Atoms in Kr-Implanted Aluminium", J. Phys. Soc.
Jpn. , 64, 800- 808 (1995).
Q. Hui, J. L. Persson, J. H. M. Beijersbergen, and
M. Takami: "Laser Spectroscopy of Neutral Atoms
in Superfluid Helium: New Environment for Spectroscopyand Chemistry", Laser Chem., 15, 221- 228(1995).
E. Vagi: "Solid Bubble Formation in Metals Implantedwith Inert Gas Ions", Materia Japan (in Japanese),(Bull. Jpn. Inst. Metals), 34, 971- 972 (1995).
T. Mizogawa, M. Sato, and Y. Awaya: "Applicationof the "MBWC" Two,.Dimensional Position Read-out Technique to a Multiwire Proportional Counter" ,Nucl. Instrum. M ethods Phys. Res. , A366 , 129- 136(1995).
.
R. Hutton, S. Huldt, B. Nystrom, I. Martinson, K.
Ando, T. Kambara, Y. Kanai, Y. Nakai , and Y.
A waya: "Beam-Foil Studies of Highly Ionized Nb",ibid., B98, 48-52 (1995).
Y. Kanai, T. Kambara, Y. Awaya, H. Ida, Y. Matsui,
T. Takayanagi, K. Wakiya, N. Nakamura, M. Koide,
S. Kitazawa, and S. Ohtani: "Ejected Electron Spectra from Triplet States of Doubly-Excited 0 4+ andNe 6 +", ibid. , pp. 81- 84.
L. P. Presnyakov, H. Tawara, and D. B. Uskov: "Double Electron Removal from H- in Collisions with
Highly Charged Ions", ibid. , pp. 332- 334.
Y. Zou, Y. Awaya, C. P. Bhalla, T. Kambara, Y.
Kanai, M. Oura, Y. Nakai, K. Ando, A. Hitachi, and
S. Kravis: "L-Subshell Vacancy Production of Fast
Argon Ions in Solids", ibid., B99, 1- 3 (1995) . .
R. Hutton, S. Huldt, B. Nystrom, I. Martinson, K.
Ando , T. Kambara, Y. Kanai, Y. Nakai, Y. Awaya,
and J. Sugar: "Experimental Lifetimes for the 3p 2PLevels in Na-Like Nb(Nb 30 +)" , Phys. Rev. A , 51,
143- 146 (1995).
M. F. V. Lundsgaad, N. Toshima, and C. D. Lin:
"Electron Capture from Circular Rydberg Atoms",
ibid., pp. 1347-1350.
Y. Zou, Y. Awaya, C. P. Bhalla, T. Kambara, Y.
Kanai , M. Oura, Y. Nakai, K. Ando, A. Hitachi, and
S. Kravis: "Inner-Shell Vacancy Distribution in ~n­ergetic Ar Ions by Penetration in Solids", ibid., pp.
3790-3798.
J. Z. Tang, C. D. Lin, B. Zhou, and I. Shimamura:"Resonances in Photodetachment of H- (2p2 3 p e)",ibid., pp. 4694-4698.
J. Z. Tang and I. Shimamura: "High-Lying Doubly
Excited Resonances in the Photodetachment of H- ",ibid. , pp. R1738- R1741.
Y. Kino, M. R. Harston, I. Shimamura, E. A. G . Armour, and M. Kamimura: "Normalization of the
Asymptotic Form of Three-Body (dtjL)+ and (ddjL)+
Wave Functions", ibid., 52 , pp. 870- 873 (1995).
S. Kravis, H. Saitoh, K. Okuno, K. Soejima, M.
Kimura, L Shimamura, Y. Awaya, Y. Kaneko , M.
Oura, and N. Shimakura: "Single- and DoubleCharge-Exchange Cross Sections for Arq + +H2 (q =6, 7, 8, 9, and 11) Collisions from 6 eV to 11 keV" ,ibid., pp. 1206-1212.
J. L. Persson, Q. Hui, M. Nakamura, and M. Takami:"Optical Spectra of Metal Dimers and Trimers inSuperfluid Helium", ibiq,. , pp. 2011-2015.
B. D. DePaola, M.-T. Huang, S. Winecki , M. P.
Stockli, Y. Kanai , S. R. Lundeen, C. W . Fehrenbach,and S. A. Arko: "Absolute Cross Sections for Charge
Capture from Rydberg Targets by Slow Highly
Charged Ions", ibid., pp. 2136- 2140. .'J. Z. Tang and I. Shimamura: "Double Photoionization of Helium at Low Photon Energies", ibid., pp.
269

R3413-R3416.
E. Karlsson, R. Wappling, S. W. Lidstrom, O.
Hartmann, R. Kadono, R. F. Kieft, R. Hempelmann,and D. Richter: "Quantum Diffusion and Localization of Positive Muons in Superconducting Aluminium", ibid., pp. 6417- 6423.
K. Kumagai, K. Kawano, H. Kagami, G. Suzuki,
Y. Matsuda, 1. Watanabe, K. Nishiyama, and K.
N agamine: "Magnetic Order and Suppression of Superconductivity around x = 0.12 in La2_xBaxCu04
and La2-xSrxCu04", Physica, C235/240, 17151716 (1994).
Q. Hui, J. L. Persson, J. H. M. Beijersbergen, and
M. Takami: "Spectroscopy and Dynamics of Neutral
Atoms in Superftuid Helium", Z. Phys., B98, 353357 (1995).

4.

Radiochemistry, radiation chemistry, and radiation biology

K. Eguchi-Kasai, M. Murakami, H. Itsukaichi, K.
Fukutsu, T. Kanai, Y. Furusawa, K. Sato, H. Ohara,
and F. Yatagai: "The Role of DNA Repair on Cell
Killing by Charged Particles", Adv. Space Res., 18,
109- 118 (1995).
Y. Itoh, K. H. Lee, H. Murakami, and R. Iwata: "Defect Study of Proton-Irradiated Liquid-Encapsulated
Czochralski GaAs Using the Positron-Annihilation",
Appl. Phys., A60, 57-60 (1995).
Y. Itoh, K. H. Lee, T. Nakajyo, A. Goto, N. Nakanishi,
M. Kase, M. Kanazawa, Y. Yamamoto, N. Oshima,
and Y. Ito: "Slow Positron Production Using the
RIKEN AVF Cyclotron" , Appl. Surf. Sci., 85 , 165(1995).
S. Ambe and F. Ambe: "Mossbauer Emission Spectra of 119Sn in Binary Compounds of Antimony andTellurium", Bull. Chern. Soc. lpn. , 68, 1935- 1940
(1995).
S. Enomoto, B. Liu, R. Amano, S. Ambe, and F.
Ambe: "In Vivo Behavior of Various Rare Earth Elements in Lipogenous Diabetes Model Mice by Using
the Multitracer Technique", J. Inorg. Biochem., 59,353 (1995).
R. Hirunuma, S. Enomoto, M. Yanaga, R. Amano, K.
Endo, S. Ambe, and F. Ambe: "Multitracer Studies
of Behavior of Trace Elements in Rats and Mice",
ibid. , p. 354.
F. Ambe, Y. Ohkubo, S. Ambe, Y. Kobayashi, T.
Okada, Y. Yanagida, J. Nakamura, K. Asai, Y.
Kawase, and S. Uehara: "Local Structure and Valence of Impurity Ions in Oxides by TDPAC andMossbauer Emission Sectroscopy" , J. Radioanal.
Nucl. Chern., 190, 215- 224 (1995).
S. Ambe and F. Ambe: "Mossbauer Study of Deffect119Sn Atoms with Ligands from Silver to Iodine",
ibid., pp. 425- 430.
S. Ambe, S. Y. Chen, Y. Ohkubo, Y. Kobayashi, H.
Maeda, M. Iwamoto, M. Yanokura, N. Takematsu,
270

and F. Ambe: "'Multitracer' A New Tracer Technique - Its Principle, Features, and Application",
ibid. , 195, 297- 303 (1995).
S. Ambe, Y. Ohkubo, Y. Kobayashi, M. Iwamoto, H.
Maeda, and M. Yanokura: "Multitracer Study on
Transport and Distribution of Metal Ions in Plants" ,ibid., pp. 305- 313.
Y. Ohkubo, Y. Kobayashi, K. Harasawa, S.
Ambe, T. Okada, F. Ambe, K. Asai, and S.
Shibata:"Time-Differential Perturbed-AngularCorrelation and Emission Mossbauer Studies on
99Ru Dispersed in YBa2Cu306 .8 and YBa2Cu306",
l. Phys. Chern., 99, 10629- 10634 (1995).
Y. Itoh, H. Murakami, and A. Kinoshita: "Positronium Formation and Annihilation in Porous Silicon" ,Mater. Sci. Forum, 175/178, 173- 176 (1995).
H. Kusawake, T. Saito, A. Yokoyama, K. Takesako, N.
Takahashi, H. Baba, Y. Ohkubo, and A. Shinohara:"Angular-Momentum Effect in the Fusion Reactionof 141 Pr with 40 Ar Projectiles" , Radiochim. Acta, 69 ,
65-75 (1995).
Y. Itoh: "The Study on Porous Silicon by Means of
Positron Annihilation", Radioisotopes, 14, 759- 760(1995).

5.

Material analysis

J. Kawai, S. Hayakawa, F. Esaka, S.-Y. Zhen, Y.
Kitajima, K. Maeda, H. Adachi, Y. Gohshi, andK. Furuya: "Depth Selective Chemical State Analysis of Fine Particle Using X-Ray Absorption", Anal.
Chern. , 67, 1526- 1529 (1995).
N. Arai, W. Sakamoto, and K. Maeda: "Analysis ofTrace Elements in Otoliths of Red Sea Bream Pagrus
Major" , Fish. Sci. , 61, 43- 47 (1995).
N. Arai, W. Sakamoto, and K. Maeda: "PIXE Analysisof Otoliths from Several Species of Teleost Fish", Int.
l. PIXE, 4, 123- 129 (1994).
J. Kawai and K. Maeda: "Vertical Beam PIXE for insitu Analysis of Liquids" , ibid., pp. 147-154.
K. Maeda and J. Kawai: "Water Analysis by Particle Induced X-Ray Emission (PIXE) ", Genshikaku
Kenkyu (in Japanese) , 39 , No.4, pp. 9- 26 (1994);
IONICS, 20, No. 11 , pp. 3- 21 (1994).
K. Maeda: "Application of Particle Induced X-Ray
Emission (PIXE) to Liquid Samples", Proc. Symp.
Research and Development of Beam Engineering at
62nd Spring Meet. Electrochemical Soc. J pn. 'Advanced Material-Processing Beam-Technology' , S.
Masaki (ed.), Ionics, pp. 39- 42 (1995).
J. Kawai, K. Maeda, K. Nakajima, and Y. Gohshi:"Reply to "Comment on 'Relation between Copper L X-Ray Fluorescence and 2p X-Ray Photoelectron Spectroscopies" , Phys. Rev. B, 52, 6129-6131(1995).
J. Kawai, K. Maeda, N. Sakauchi, and I. Konishi:"Strong X-Ray Emission from Electrified Material",
Spectrochim. Acta, 50B, L1- L4 (1995).

VIII. LIST OF PREPRINTS1995
RIKEN-AF -NP
184 M. Yokoyama, T. Otsuka, and N. Fukunishi: "Giant Quadrupole Excitation in Nuclei with Neutron Skin"

185 T. Otsuka, M. Yokoyama, N. Fukunishi, and K. H. Kim: "Structure and Excitation of Nuclei Far from
Stability"
186 1. Tanihata: "Nuclear Structure Studies from Reaction Induced by Radioactive Nuclear Beams"

187 A. A. Korsheninnikov, D. V. Aleksandrov, N. Aoi, Y. Doki, N. Inabe, M. Fujimaki, T. Kobayashi, H.
Kumagai , C.-B. Moon, E. Yu. Nikolskii, M. M. Obuti, A. A. Ogloblin, A. Ozawa, S. Shimoura, T. Suzuki,
1. Tanihata, Y. Watanabe, M. Yanokura, and K. Yoshida: "Experimental Studies of Light Rich Nuclei"
Y. Suzuki, K. Arai, Y. Ohbayashi, and K. Varga: "Study of Halo Structure in Light Nuclei with a Multicluster Model"
M. Ishihara: "Current Topics on Light Neutron-Rich Nuclei"
Y. Ogawa, Y. Suzuki, and K. Yabana: "Transverse Momentum Distributions of a 9Li Fragment in the (11 Li,
9Li) Reaction and Neutron Correlations"T. Nakamura, S. Shimoura, T. Kobayashi, T. Teranishi, K. Abe, N. Aoi, Y. Doki, M. Fujimaki, N. Inabe, K.
Katori, T. Kubo, H. Okuno, T. Suzuki, 1. Tanihata, Y. Watanabe, A. Yoshida, and M. Ishihara: "Coulomb
Dissociation of a Halo Nucleus 11 Be and Direct Breakup Mechanism"
Ka-Hae Kim, T. Otsuka, and M. Tohyama: "Transfer and Fusion Reactions of Unstable Nuclei"
T. Otsuka, A. Muta, M. Yokoyama, N. Fukunishi, and T. Suzuki: "Structure of Nuclei Far from Stability"
K. Varga, Y. Suzuki, and 1. Tanihata: "Microscopic Multicluster Description of the 7Li-7Be, 8Li- 8B, and
9Li_ 9C Mirror Nuclei"
1. Tanihata: "RI Beam Factory Project"

H. Toki, D. Hirata, Y. Sugahara, and 1. Tanihata: "Relativistic Many Body Approach for Unstable Nuclei
and Supernova"
188 A. Muta and T. Otsuka: "Deformed Woods-Saxon Potential Approach to the Structure of 11 Be"
189 H. Okuno, K. Asahi, H. Ueno, H. Izumi, H. Sato, M. Adachi, T. Nakamura, T. Kubo, N. Inabe, A. Yoshida,
N. Fukunishi, T. Shimoda, H. Miyatake, N. Takahashi, W.-D. Schmidt, and M. Ishihara: "Measurement of
the Magnetic Moments of 14B and 15B Using Fragment Spin Polarization"

190 K. Varga and Y. Suzuki: "Precise Solution of Few-Body Problems with the Stochastic Variational Method"
191 T. Horibata, M. Oi, and N. Onishi: "Signature Splitting in Tilted Axis Rotating States"
192 T. Kobayashi, K. Yoshida, and H. Kitagawa: "Recent Progresses at RIKEN Accelerator Facility"

193 K. Yuasa-Nakagawa, T. Nakagawa, K. Furutaka, K. Matsuda, Y. Futami, K. Yoshida, J. Kasagi, S. M. Lee,
T. Suomijarvi, W. Q. Shen, and T. Matsuse: "Entrance Channel Effect on the Pre-scission Time of Binary
Decay for the Medium Mass Nuclei (Mass !"V110)"
194 T. Horibata and N. Onishi: "Theory, Self-Consistent Three-Dimensional Cranking Calculation Based on
HFB 1. Energy Surface and Gamma-Deformation for 1820s"
195 K. Sumiyoshi, H. Suzuki, and H. Toki: "Theory, Influence of the Symmetry Energy on the Birth of NeutronStars and Supernova Neutrinos"271

196 E. Ideguchi , Y. Gono, S. Mitarai, T. Morikawa, A. Odahara, M. Kidera, M. Shibata, H. Tsuchida, K.
Miyazaki, M. Oshima, Y. Hatsukawa, S. Hamada, H. Iimura, M. Shibata, T. Ishii, T. Murakami, H. Kusakari,
M. Sugawara, T. Kishida, K. Morita, H. Kumagai , and M. Ishihara: "High-Spin States in 148Tb"
197 M. Honma, T. Mizusaki, and T. Otsuka: "Diagonalization of Hamiltonians for Many-Body Systems by
Auxiliary Field Quantum Monte Carlo Technique"
198 K. Sumiyoshi, K. Oyamatsu, and H. Toki: "Neutron Star Profiles in the Relativistic Brueckner Hartree
Fock Theory"
199 Y. Mochizuki, K. Oyamatsu, and T. Izuyama: "Nuclear Lattice Deformation Inside Neutron Stars and theOrigin of Pulsar Glitches"
200 T. Ariga, K. Uchiyama, S. Ozawa, K. Osada, M. Hirai, A. Yamashita, A. Yoshimi, K. Kodaka, and H.
Okuno: "Heisei 6nen Gakui Ronbun Happyokai"
201 A. Mengoni, T. Otsuka, and M. Ishihara: "Direct Radiative Capture of P-Wave Neutrons"
202 A. Ono and H. Horiuchi: "Improvement of the Nucleon Emission Process and the Statistical Property in
Molecular Dynamics"
203 H. Izumi, K. Asahi, H. Ueno, H. Okuno , H. Sato, K. Nagata, Y. Horii , M. Adachi, N. Aoi, A. Yoshida, G.
Liu, N. Fukunishi, and I. Ishihara: "Electric Quadrupole Moments of Neutron-Rich Nuclei 14B and 15B
204 T. Suzuki, H. Geissel, O. Bochkarev, L. Chulkov, M. Golovkov, D. Hirata, H. Irnich, Z. Janas, H. Keller ,T. Kobayashi, G. Kraus, G. Munzenberg, S. Neumaier, F. Nickel, A. Ozawa, A. Piechaczeck, E. Roeckl,
W. Schwab, K. Suemmerer, K. Yoshida, and 1. Tanihata: "Neutron Skin of Na Isotopes Studied via theInteraction Cross Sections"
205 K. Varga and Y. Suzuki: "Precise Solution of Few-Body Problems with Stochastic Variational Method on
Correlated Gaussian Basis"
206 S. Kim and S. Ohta: "Light Hadron Masses with 4 GeV Cutoff and L = 2.4 fm"
207 S. Ohta: "Self-Test Monte Carlo Method"
208 H. Hofmann, F. A. Ivanyuk, and S. Yamaji: "On the Nature of Nuclear Dissipation, as a Hallmark forCollective Dynamics at Finite Excitation"
209 H. Kurasawa and T. Suzuki: "Macroscopic Model of Giant Resonance States in Neutron-Rich Nuclei"
210 H. Kurasawa and T. Suzuki: "Quasielastic Electron Scattering"
211 H. Kurasawa and T. Suzuki: "A Sum-Rule Constraint on the Soft Dipole Mode"212 H. Kurasawa and T. Suzuki: "The Mean Energy, Strength and Width of the Double Giant Dipole States"
213 1. Tanihata: "Neutron Halo Nuclei"
214 A. Ono and H. Horiuchi: "Statistical Properties of Antisymmetrized Molecular Dynamics for Non-NucleonEmission and Nucleon-Emision Processes"
215 A. A. Korsheninnikov, E. Yu. Nikolskii , T. Kobayashi, A. Ozawa, S. Fukuda, E. A. Kuzmin, S. Momota, B.
G. Novatakii, A. A. Ogloblin, V. Pribora, I. Tanihata, and K. Yoshida: "Spectroscopy of the Halo Nucleus
11 Li by an Experimental Study of 11 Li + P Collisions"
216 H. Ueno, K. Asahi, H. Izumi, K. Nagata, H. Ogawa, A. Yoshimi, H. Sato, M. Adachi, Y. Hori , K. Mochinaga,
H. Okuno, N. Aoi, M. Ishihara, A. Yoshida, G. Liu , T. Kubo, N. Fukunishi, T. Shimoda, H. Miyatake , M.
272

Sasaki, T. Shirakura, N. Takahashi, S. Mitsuoka, and W.-D. Schmidt: "Magnetic Moments of 17N and 17B"
217 M. Honma, T. Mizusaki, and T. Otsuka: "Quantum Monte Carlo Diagonalization Method for Realistic
Shell"

273

IX. PAPERS PRESENTED AT MEETINGS
1.

Accelerator
physics

development

a ndaccelerator

T. Uesaka, T. Wakui, M. Wakasugi, A. Minoh, Y.
Yano, H. Sato, K. Sakai, and Y. Masuda: "Development of Polarized 3He Gas Target at RIKEN",
1995 Spring Meet. Phys. Soc. Jpn., Yokohama, Mar.
(1995).
M. Niimura, T. Kageyama, T. Nakagawa, A. Goto,
and Y. Yano: "Physics for ECRIS Beam-Current
Upgrading Technologies Such as Electron Beam Injection, Wall Coating, and Gas Mixing", 12th Int.
Workshop on ECR Ion Sources, Wako, Apr. (1995).
T. Nakagawa, T. Kageyama, M. Kase, A. Goto, andY. Yano: "Production of Highly Charged Ions from
Oxide in RIKEN 10 GHz ECRIS", ibid.
Y. Batygin, A. Goto, and Y. Yano: "Nonlinear Effectof Einzel Lens to the Beam Extracted from ECR
Source", ibid.
M. Niimura, H. Amemiya, A. Goto, and Y. Yano:"A veraged Excitation Rate Coefficient Calculationof HeI up to T e = 1000 eV and Plasma Potential
Measurement up to ECR-Heated Ellipsoid", ibid.
Y. Batygin, A. Goto, and Y. Yano: "Hollow Beam Profile in the Extraction System of ECR Ion Source",
Particle Accelerator Conf., Dallas, U.S.A., May(1995).
Y. Batygin: "Invariability of Intense Beam Emittancein Nonlinear Focusing Channel", ibid.
D. Bruhwiler and Y. Batygin: "Beam Transport for
Uniform Irradiation: Nonlinear Space Charge Forces
and the Effect of Boundary Conditions", ibid.
T. Uesaka, T. Wakui, M. Wakasugi, A. Minoh, Y.
Yano, H. Sato, K. Sakai, and Y. Masuda: "Development of Polarized 3He Gas Target at RIKEN", Int.
Workshop on Polarized Beams and Polarized Gas
Targets, Koeln, Germany, June (1995).
Y. Yano: "RIKEN Accelerator Research Facility(RARF), Its New Project 'RI Beam Factory', andOther Major Heavy-Ion Accelerator Facilities inJapan", Simposio Nipo-Brasileiro de Ciencia e Technilogia, Sao Paulo, Brazil, Aug. (1995).
O. Kamigaito, A. Goto, Y. Miyazawa, T. Chiba, M.
Hemmi, S. Kohara, M. Kase, Y. Batygin, and Y.
Yano: "Development of a Variable-Frequency RFQ
Linac for the RILAC" , 20th Linear Accelerator Meet.
Jpn., Osaka, Sept. (1995).
M. Kase, N. Inabe, A. Goto, T. Kageyama, 1.
Yokoyama, M. Nagase, S. Kohara, T. Nakagawa, K.
Ikegami, O. Kamigaito, J. Fujita, and Y. Yano: "TheOperation of RIKEN Ring Cyclotron", 10th Symp.
on Accelerator Science and Technology, Hitachinaka,
Oct. (1995).
M. Niimura, T. Nakagawa, A. Goto, and Y. Yano:"Next-Step ECRIS and 2 m Length 4.52 GeV Advanced Accelerator: Novel Extraction of Trapped
274

Ions and their Acceleration-Final Focusing by Nonneutral and Neutral Plasmas" , ibid.
T. Mitsumoto, A. Goto, T : Kawaguchi, Y. Tanaka, T.
Kubo, H. Okuno, T. Tominaka, S. Fujishima, andY. Yano: "Design Study of Sector Magnet for the
RIKEN Superconducting Ring Cyclotron (I)", ibid.
T. Nakagawa, Y. Miyazawa, M. Hemmi, T. Chiba, N.
Inabe, M. Kase, T. Kageyama, O. Kamigaito, E.
Ikezawa, A. Goto, and Y. Yano: "Development of
RIKEN 18 GHz ECRIS", ibid.
O. Kamigaito, A. Goto, Y. Miyazawa, T. Chiba, M.
Hemmi, S. Kohara, M. Kase, Y. Batygin, and Y.
Yano: "Development of a Variable-Frequency RFQ
Linac for the RILAC", ibid.
Y. Yano, A. Goto, T. Katayama, and RIBF Group:"RIKEN RI Beam Factory Project", ibid.
M. Kase, N. Inabe, 1. Yokoyama, A. Goto, and Y.
Yano: "Applications of MCP Phase Monitor to Operations of RIKEN Heavy Ion Accelerators", 14th
Int. Conf. on Cyclotron and Their Applications,
Cape Town, South Africa, Oct. (1995).
T. Mitsumoto, T. Kawaguchi , T . Kubo, H. Okuno,
T. Tominaka, Y. Tanaka, S. Fujishima, K. Ikegami,
A. Goto, and Y. Yano: "Design Study of Sector
Magnets of Superconducting Ring Cyclotron for the
RIKEN RI Beam Factory", ibid.
Y. Yano, A. Goto, T. Katayama, and RIBF Group:"The RIKEN RI Beam Factory Project", ibid.
A. Goto, Y. Miyazawa, M. Hemmi, O. Kamigaito, T.
Nakagawa, M. Kase, T. Chiba, N. Inabe, S. Kohara,
T. Kageyama, Y. Batygin, E. Ikezawa, and Y. Yano:"Construction of a New Pre-injector System for the
RILAC", ibid.
T. Kubo, H. Okuno, K. Ikegami, T. Kawaguchi,
T. Tominaka, T. Mitsumoto, S. Fujishima, A.
Goto, and Y. Yano: "RI-Beam Factory Project(I)Superconducting Ring Cyclotron", 1995 Fall Meet.
Cryognenics and Superconductivitiy, Akita, Nov.
(1995) .
T. Kawaguchi, T. Mitsumoto, T. Kubo, T. Tominaka,
H. Okuno, Y. Tanaka, S. Fujishima, K. Ikegami, A.
Goto, and Y. Yano: "RI Beam Factory Project (II)- Superconducting Sector Magnet-", ibid.
T. Tominaka, H. Okuno, Y. Tanaka, T. Kubo,
T. Mitsumoto, T. Kawaguchi, S. Fujishima, K.
Ikegami, A. Goto, and Y. Yano: "RI Beam Factory Project(III) -Beam Injection and Extraction
Systems-", ibid.
T. Kawaguchi, T. Kubo, T. Mitsumoto, T. Tominaka,
S. Fujishima, H. Okuno, Y. Tanaka, K. Ikegami, A.
Goto, and Y. Yano: "Design Study of Sector Magnet for the RIKEN Superconducting Ring Cyclotron(II)", 10th Symp. on Accelerator Science and Technology, JAERI Conf., Hitachinaka, Oct. (1995).
N. Inabe, M. Kase, 1. Yokoyama, A. Goto, and Y.
Yano: "Development of a Single-Bunch Selector forRIKEN Ring Cyclotron", ibid.
A. Goto, Y. Miyazawa, M. Hemmi, O. Kamigaito, T.
Nakagawa, M. Kase, T. Chiba, N. Inabe, S. Kohara,
T. Kageyama, Y. Batygin, and Y. Yano: "Construction of a New Pre-injector System for the RILAC",
ibid.
M. Takanaka and T. Katayama: "Beam Current Limitations Due to Single-Beam Collective Effects in
the Ion Storage Ring of RIKEN RI Beam Factory
Project", ibid.
Y. Batygin, A. Goto, and Y. Yano: "Hollow Beam
Formation in the Extraction Region of ECRIS", ibid.
Y. Batygin and T. Katayama: "Study of Incoherent
Beam-Beam Effects at Radioactive Isotope Beam
Factory", ibid.
Y. Batygin, A. Goto, O. Kamigaito, and Y. Yano:"Effect of Field Variation on Beam Parameters in
RIKEN RFQ Linac", ibid.
N. Nakanishi, T. Shikata, S. Fujita, and T. Kosako:"Comparison of Calculated Shielding Effects for 8
Materials", ibid.
Y. Batygin: "On Space Charge Dominated BeamTransport without Emittance Growth", 8th ICFA
Workshop on Space Charge Dominated Beams, Indiana, U.S.A., Oct. (1995).
2.

Nuclear physics and nuclear instrumentation

C. Signorini: "Fusion at the Barrier with Stable andRadioactive Nuclei: Present and Future", Tours
Symp. on Nucl. Phys. II, Tours, France, Aug. (1994).
H. Kurasawa and T. Suzuki: "Macroscopic Model of
Giant Resonance States in Neutron-Rich Nuclei",
3rd IN2P3-RIKEN Symp. on Heavy Ion Collisions,
Wako, Oct. (1994).
Y. Ogawa, Y. Suzuki, and K. Yabana: "Transverse
Momentum Distributions of a 9Li Fragment in the(11 Li, 9Li) Reaction and Neutron Correlations" , Int.
Symp. on Physics of Unstable Nuclei, Niigata, Oct.Nov. (1994).
H. Kurasawa and T. Suzuki: "Quasielastic Electron
Scattering", Korea-Japan Joint Symp. on Recent Development of Nuclear Study using Electron and Photon Beams, Seoul and Pohang, Korea, Dec. (1994).
H. Sato, Y. Hori, K. Mochinaga, M. Adachi, and K.
Asahi: "Development of Polarized 129Xe Stopper
as a Polarizer for Unstable Nuclei", Symp. on Science with Radioactive Nuclear Beams, Tanashi, Jan.
(1995).
Y. Mochizuki, K. Oyamatsu, and T. Izuyama: "Effectsof Deformed Nuclei on Neutron Star Glitches", ibid.
A. Ozawa, T. Kobayashi, D. Hirata, 1. Tanihata, O.
Yamakawa, K. Sugimoto, D. Olson, W. Christie, and
H. Wieman: "Interaction Cross Sections and Radiiof the Light Proton Rich Nuclei", ibid.
K. Sumiyoshi: "Influence of the Symmetry Energy on
the Cooling of Protoneutron Stars and Supernova
Neutrinos", ibid.

Y. Mochizuki: "Abnormal Braking Indices as a Indicator of Glitching Pulsars", Winter School on Nuclear
Astrophysics, Sponsored by Science of Short-Lived
Nuclear Beams, Shiozawa, Feb. (1995).
T. Horibata: "Calculation of Signature Splitting",
RIKEN Symp. on Recent Progress at Accelerator Facility, Wako, Mar. (1995).
T. Kohno: "Radiation Observation in Space", Workshop on Space Environment Monitoring from Space,
Nagoya, Mar. (1995).
A. Ono and H. Horiuchi: "Improvement of the
N ucleon-Emission Process in AMD and Its Statistical Property", 50th Ann. Meet. Phys. Soc. J pn.,
Yokohama, Mar. (1995).
H. Sato, Y. Hori, K. Mochinaga, M. Adachi, and K.
Asahi: "Polarization of Xe Nuclear Spin by Using
the Optical Pumping Method II", ibid.
N. Aoi: "j3-decay of Light Neutron Rich Nuclei", ibid.
T. Horibata, M. Oi, and N. Onishi: "Calculation of
Signature Splitting" , ibid.
Y. Sugaya, D. Ashery, J. Chiba, H. Ito, K. Kimura,Yu. T. Kiselev, S. Kouda, K. Miyano, T. Murakami,
T. Nagae, Y. Nakai, M. Nomachi, H. Ochiishi, S.
Sawada, M. Sekimoto, T. Shibata, T. Suzuki, K. H.
Tanaka, M. K. Vlasov, Y. Yamanoi, K. Yasuda, andY. Yoshimura: "Subthreshold Anti Proton Production Nucleus Collision withp, d, and 0: Particle", ibid.
T. Teranishi, M. Ishihara, H. Sakurai, M. Hirai, T.
Motobayashi, S. Shimoura, H. Murakami, Y. Ando,
N. Iwasa, T. Nishio, S. Moriya, Y. Yanagisawa,
T. Kikuchi, T. Uchibori, Y. Watanabe, and T.
Nakamura: "Charge Exchange Reactions of 11 Li" ,ibid.
H. Koura, M. Uno, T. Tachibana, Y. Shigeta, and M.
Yamada: "Semi-Empirical Shell Energy and Atomic
Mass Formula II", ibid.
Y. Sugahara, K. Sumiyoshi, and H. Toki: "Study of
the Light Nuclei in the Relativistic and the NonRelativistic Models", ibid.
N. Nakanishi, S. Nakajima, S. Fujita, T. Minemura, Y.
Kangyou, M. Watanabe, and H. Ohishi: "Measurements of Eleven Neutron Activation Cross Sections
Using 113 MeV Proton Beams", ibid.
S. Takahara, N. Onishi, and N. Tajima: "Deformed
Hartree-Fock Calculation of Z 2: 82 Nuclei (I)", ibid.
Y. Aoki, R. Sasaki, T. Ohtsuki, J. Kasagi, K. Furutaka,
Y. Futami, K. Matsuda, K. Yuasa-Nakagawa, T.
Nakagawa, K. Yoshida, and T. Suomijarvi: "Giant
Dipole Resonances at Ex
150 MeV Observed in
Heavy Ion Fusion Reactions", ibid.
H. Ogawa, N. Aoi, M. Ito, K. Asahi, H. Ueno, H.
Izumi, K. Nagata, A. Yoshida, H. Okuno, G. Liu,
S. Mitsuoka, M. Adachi, and M. Ishihara: "Measurements of Branching Ratio for the Unique First
Forbidden Beta Decay of 14B", ibid.
K. Sumiyoshi, K. Oyamatsu, and H. Toki: "Equation of State and Neutron Stars in the Relativistic
Brueckner Hartree Fock Theory", ibid.
f'.J

275

A. A. Korsheninnikov: "Experimental Studies of Light
Exotic Nuclei", 15th Nuclear Physics Division Conf.
on LEND 95 of European Physical Society, St. Petersburg, Russia, Apr. (1995).
A. A. Korsheninnikov: "Experimental Studies of Light
Neutron-Rich Nuclei" , 2nd RIKEN/INFN(Italy)
Joint Symp., Wako, May (1995).
A. Yoshida: "Measurement of Fusion Cross Section
with Neutron Rich RI Beam", ibid.
C. Signorini: "Fusion and Break-Up Around the
Coulomb Barrier with Halo/Loosely Bound Unstable Nuclei" ,ibid.
A. Ono and H. Horiuchi: "Nucleon Flow and Fragment
Flow in Heavy Ion Collisions Studied with AMD,"ibid.
M. Wakasugi: "Laser Spectroscopy on Radioactive Isotopes of Refractory Elements" , ibid.
T. Wada, Y. Aritomo, M. Ohta, Y. Abe, and S.
Yamaji: "Fission as Dissipative Process" , ibid.
K. Yuasa-Nakagawa, T. Nakagawa, Y. Futami, K.
Furutaka, K. Matsuda, K. Yoshida, T. Mizota, Y.
Honjo, S. Tomita, T. Suomijarvi, W. Q. Shen, J.
Kasagi, T. Matsuse, and S. M. Lee: "Angular Momentum Dependence of Pre-Scission Time for Binary
Decay in Medium Mass Nuclei", YITP Symp. on
Similarities and Differences of Microcluster and Nucleus, Kyoto, June (1995).
T. Motbbayashi: "Experimental Study of Nuclear Reactions Related to Solar Neutrino Production" , 4thInt. Symp. on Weak and Electromagnetic Interaction
in Nuclei (WEIN '95), Osaka, June (1995).
A. A. Korsheninnikov: "Experimental Studies ofLight Exotic Nuclei", Int. Conf. on Exotic Nuclei
and Atomic Masses ENAM'95, Arles, France, June
(1995).
M. Uno, H. Koura, T. Tachibana, and M. Yamada:"Nuclear Shell Energies and Deformations in Mass
Formulas", ibid.
S. Shimoura: "Spectroscopy of Neutron-Rich Nuclei
via Direct Reactions using Secondary Nuclear Beams
at Several Tens of MeV Per Nucleon", ibid.
K. Matsuta, M. Tanigaki, M. Fukuda, T. Minamisono,
Y. Nojiri, M. Mihara, T. Onishi, T. Yamaguchi,
A. Harada, M. Sasaki, T. Miyake, K. Minamisono,
T. Fukao, K. Sato, Y. Matsumoto, T . Ohtsubo,
S. Fukuda, S. Momota, K. Yoshida, A. Ozawa, T.
Kobayashi, I. Tanihata, J. R. Alonso , G. F. Krebs,
and T. J. M. Symons: "Magnetic Moments of Proton
Drip-Line Nuclei", ibid.
T. Motobayashi, N. Iwasa, T. Kikuchi, Y. Ando, M.
Kurokawa, S. Moriya, H. Murakami , T. Nishio, J.
Ruan(Gen), S. Shimoura, S. Shirato, T. Uchibori,Y. Yanagisawa, N. Inabe, M. Ishihara, T. Kubo. Y.
Watanabe, M. Hirai, T. Nakamura, H. Sakurai, T.
Teranishi, M. Gai, R. H. France III, K. I. Hahn,
Z. Zhao, Y. Futami, K. Furutaka, Th. Delbar, C.
Michotte, and P. Lipnik: "Coulomb Dissociation of
8B and Sonar Neutrino Problem" , ibid.
276

T . Ichihara, M. Ishihara, H. Ohnuma, T. Niizeki, T.
Yamamoto, K. Katoh, T. Yamashita, Y. Hara, Y.
Fuchi, S. Kubono, M. H. Tanaka, H. Okamura, S.
Ishida, T. Uesaka, and Y. Satou: "Spin-Flip and
Non-Spin-Flip Isovector -Excitations Observed in the2
3
C ,12 N) andC ,13 N) Reactions at E/ A=100135 MeV" , Groningen Conf. on Giant Resonances,
Groningen, The Netherlands, June-July (1995).
Y. Okamoto, K. Endo, and R. Hirashima: "Try to
Make a New T ype Gamma Camera Using Cooled
CCD Camera" , 32nd Ann. Meet. on Radioisotopes
in the Physical Sciences and Industries, Tokyo, July
(1995).
Y. Itoh, T. Kakizaki, K. Tanaka, A. Goto, N.
Nakanishi, M. Kase, N. Oshima, T. Suzuki, I.
Kanazawa, T. Nakajyo, and Y. Ito: "Slow Positron
Production Using RIKEN AVF Cyclotron II", ibid.
S. Kim and S. Ohta: "Light Hadron Masses with
4-GeV Cutoff and L = 2.4 fm", Int. Symp. Lattice Field Theories 95, Melbourne, Australia, July
(1995).
K. Sumiyoshi: "Unstable Nuclei and Relativistic EOS
for Neutron Stars and Supernovae", RCNP Workshop on Structure and Reaction of Unstable Nuclei,
Osaka, July (1995).
Y. S. Mochizuki, K. Oyamatsu, and T. Izuyama: "Nuclear Deformation Induced by Superfluid Vortices in
the Neutron Star Crusts", ibid.
T. Teranishi, M. Ishihara, H. Sakurai, M. Hirai, T.
Motobayashi, S. Shimoura, H. Murakami, Y. Ando,
N. Iwasa, T. Nishio, S. Moriya, Y. Yanagisawa,
T. Kikuchi, T. Uchibori, Y. Wat anabe, and T.
Nakamura: "Charge Exchange Reactions of 11 Li" ,ibid.
Y. Ogawa, K . Arai , K. Varga, and Y. Suzuki: "Structure of the 9Be and lOBe Nuclei in a Microscopic
Multicluster Model" , ibid.
T. Nakamura: "Coulomb Excitation of 11 Be", ibid.
K. Oyamatsu: "Symmetry Energy and Nuclei in Neutron Stars", ibid.
T. Nakagawa, K. Yuasa-Nakagawa, K. Yoshida, K.
Furutaka, K. Matsuda, Y. Futami, T. Mizota,
Y. Honjo , S. Tomita, S. M. Lee , J. Kasagi, T.
Suomijarvi, W. O. Shen, and T . Matsuse: "Angular Momentum Effect on t he Pre-Scission Time andMass Equilibration from Medium Mass Nuclei", Int.
Nucl. Phys. Conf. , INPC '95 , Beijing, China, Aug.
(1995).
K. Sugawara-Tanabe: "Magnet ic Properties in a Superdeformed Nucleus", ibid.
A. Ono and H. Horiuchi~ "Fragmentation Reactionsat Medium Energies St udied with Ant isymmetrized
Molecular Dynamics", i bid.
A. Mengoni , T . Otsuka, and M. Ishihara: "The Direct
Radiative Capture Process and the Neutron Halo
Structure of Nuclear Excited States", ibid.
C. Signorini:"Heavy Ion Reaction Around the
Coulomb Barrier" , ibid.

eeY. Watanabe: "Effects of Break-Up in the Fusion of
11 Be with 209Bi", ibid.
H. Izumi, K. Asahi, H. Ueno, H. Okuno, H. Sato, K.
Nagata, Y. Hori, M. Adachi, N. Aoi, A. Yoshida,
G. Liu, N. Fukunishi, and M. Ishihara: "Measurements of Electric Quadrupole Moments of NeutronRich Nuclei 14Be and 15B", 10th Int. Conf. on Hyperfine Interactions, Leuven, Belgium, Aug. (1995).
K. Matsuta, T. Minamisono, M. Tanigaki, M. Fukuda,
Y. Nojiri, M. Mihara, T. Onishi , T. Yamaguchi,
A. Harada, M. Sasaki, T. Miyake, K. Minamisono,
T. Fukao, K. Sato, Y. Matsumoto, T. Ohtsubo,
S. Fukuda, S. Momota, K. Yoshida, A. Ozawa, T.
Kobayashi, I. Tanihata, J. R. Alonso, G. F. Krebs,
and T. J. M. Symons: "Magnetic Moments of Proton
Drip-Line Nuclei 13 0 and 9C", ibid.
M. Tanigaki, K. Matsuta, M. Fukuda, T. Minamisono,
Y. Nojiri, M. Mihara, K. Minanisono, T. Fukao, K.
Sato, Y. Matsumoto, T. Ohtsubo, S. Fukuda, S.
Momota, K. Yoshida, A. Ozawa, T. Kobayashi, I.
Tanihata, J. R. Alonso, G. F. Krebs, and T. J. M.
Symons: "Quadrupole Moment of Proton Dripline
Nucleus 13 0 (pr = 3/2-, T 1/ 2 = 8.6 ms)" , ibid.
K. Matsuta, M. Fukuda, M. Tanigaki, T. Minamisono,
Y. Nojiri, H. Akai, T. Izumikawa, M. Nakazato, M.
Mihara, T. Yamaguchi , A. Harada, M. Sasaki, T.
Miyake, T. Onishi, K. Minamisono, T. Fukao, K.
Sato, Y. Matsumoto, T. Ohtsubo, S. Fukuda, K.
Yoshida, A. Ozawa, S. Momota, T. Kobayashi , I.
Tanihata, J. R. Alonso, G. F. Krebs, and T. J. M.
Symons: "Hyperfine Interaction of 13 0 and 23Mg
Implanted in Pt" , ibid.
A. Ono and H. Horiuchi: "Fragmentation Described by
the Improved Antisymmetrized Molecular Dynamics" , 2nd Int. Symp. on Heavy Ion Physics and Its
Applications, Lanzhou , China, Aug. (1995).
T. Kakizaki, Y. Itoh, K. H. Lee, K. Tanaka, A.
Goto, N. Nakanishi , M. Kase , and Y. Ito: "Generation of Slow Positron Beam from Short Lifetime Positron Emitters" , 56th Meet. Jpn. Soc. Appl.
Phys. , Kanazawa, Aug. (1995).
Y. S. Mochizuki and T. Izuyama: "A Model for
the Physical Origin of Neutron Star Glitches", Int.
Workshop on Elementary Processes in Astrophysical
Dense Matter, Aspen, U.S.A. , Aug.- Sept. (1995).
Y. S. Mochizuki: "A Expected Glitch in PSR B175724" , ibid.
T. Kohno, A. Turtelli Jr. , T. Kohno, U. B. Jayanthi,
J. H. Adams Jr. , I. M. Martin, A. A. Gusev, G. I.
Pugacheva, H. Kato, K. Nagata, A. J. Tylka, and
P. R. Boberg: "Anomalous and Solar Cosmic Ray
Observations with the First Brazilian Scientific Microsatellite", 24th Int. Cosmic Ray Conf. , Rome,
Italy, Sept. (1995).
Y. Itoh, H. Murakami, and A. Kinoshita: "Positron/
Positronium Annihilation in Low Dimensional Silicon Materials", Int. Symp. on Si Het erostructures,
Crete, Greece, Sept. (1995).

K. Tanaka, Y. Itoh, K. H. Lee, T. Kakizaki, A. Goto,
N. Nakanishi, M. Kase, and Y. Ito: "Development of
the Targets for Online Spin-Polarized Slow Positron
Beam", ibid.
Y. Sugahara, K. Sumiyoshi, and H. Toki: "Comparisonof the Relativistic and the Non-Relativistic Models
for Properties of Unstable Nuclei", 1995 Fall Meet.
Phys. Soc. Jpn. , Kasugai, Sept. (1995).
N. Hasebe, Y. Mishima, M. Kobayashi, M. Kondo,
J. Hamada, T. Doke, J. Kikuchi, T. Hayashi,
N. Hemmi, T. Takashima, T. Kashiwagi, T.
Yanagimachi , A. Nakamoto, H. Hurukami, T.
Kohno, K. Munakata, C. Kato, K. Maezawa, Y.
Muraki , T. Koi , A. Nishida, T. Terasawa, S.
Yanagita, K. Nagata, and B. Wilken: "Observationof CIR Events with GEOTAIL Satellite II", ibid.
N. Fukunishi and I. Tanihata: "Magnetic Moment of
the Mirror Nuclei 9C and 9Li", ibid.
K. Sugawara-Tanabe and K. Tanabe: "C 4 Symmetry
in a Superdeformed State", ibid.
K. Oyamatsu, K. Sumiyoshi, and Y. Mochizuki: "Symmetry Energy and Nuclei in the Inner Crust of Neutron Stars" , ibid.
K. Arai, Y. Ogawa, Y. Suzuki, and K. Varga: "Structure of the A=9 System with Microscopic Cluster
Model", ibid.
A. Mengoni: "Neutron Capture Reaction Rates for Nuclear Astrophysics", ibid.
Y. Watanabe, T. Fukuda, A. Yoshida, Y. Watanabe,
Y. Mizoi, J. Nakano, M. Hirai, Y. Sakurai, H.
Kobinata, Y. Pu, K. Kimura, and M. Ishihara:"Measurement of Fusion Cross Section of NeutronRich Nuclei 29 AI, 31 AI" , ibid.
A. Ono and H. Horiuchi: "Application of AMD with
the Wave Packet Spread Effect to Heavy Ion Reactions" , ibid.
K . Sumiyoshi, D. Hirata, Y. Sugahara, H. Toki, and I.
Tanihata: "A Systematic Study of Deformed Nuclei
in the Relativistic Mean Field Theory" , ibid.
H. Koura, M. Uno, T. Tachibana, Y. Shigeta, and M.
Yamada: "Semi-Empirical Shell Energy and Atomic
Mass Formula III", ibid.
T. Horibata and N. Onishi: "Tilting Mechanism and
the Quasiparticle Energy" , ibid.
M. Oi, T. Horibata, and N. Onishi: "Angular Momentum Projection of Tilted Axis Rotating States", ibid.
Y. S. Mochizuki , K. Oyamatsu, and T. Izuyama: "Nuclear Deformation Induced by Superfluid Vortices in
the Neutron Star Crusts" , ibid.
H. Kitagawa and T. Hatsuda: "Gluon Distribution
Functions Using QCD Sum Rule", ibid.
S. Ishida: "Development of the Deuteron POLarimeter
DPOL at RIKEN I", ibid.
Y. Satou: "Development of the Deuteron POLarimeter
DPOL at RIKEN II", ibid.
T. Teranishi , M. Ishihara, H. Sakurai, M. Hirai, T.
Motobayashi , S. Shimoura, H. Murakami, Y. Ando,
N. Iwasa, T. Nishio, S. Moriya , Y. Yanagisawa,277

T. Kikuchi, T. Uchibori, Y. Watanabe, and T.
Nakamura: "Charge Exchange Reactions of 11 Li" ,ibid.
K. Mochinaga, H. Sato, M. Adachi, and K. Asahi: "Development of Polarized Xe Solid for Polarizing U nstable Nuclei", ibid.
Y. Aoki, R. Sasaki, T. Ohtsuki, J. Kasagi, K. Furutaka,
Y. Futami, K. Matsuda, K. Yuasa-Nakagawa, T.
Nakagawa, K. Yoshida, and T. Suomijarvi: "Giant
Dipole Resonances at Ex rv 150 MeV Observed in
40 Ar+ 92Mo, 116Sn, natNi Fusion Reactions", ibid.
S. Takahara, N. Onishi, and N. Tajima: "Deformed
Hartree-Fock Calculation of Z2:82 Nuclei (II)", ibid.
Y. Ogawa, K. Arai, K. Varga, and Y. Suzuki: "Structure of the 9Be and lOBe Nuclei in a Microscopic
Multicluster Model", ibid.
M. Yamagami, H. Utsunomiya, T. Yamagata, andK. Miki, S. Kubono, M. H. Tanaka, Y. Fuchi, Y.
Matsuyama, K. Ornata, and H. Sakurai: "Test of aHigh-Rate MWDC for Heavy-Ion Detection", ibid.
Y. Ohbayasi, K. Varga, and Y. Suzuki: "Stochastic
Variational Method for Few-Nucleon Systems with
Realistic Forces", ibid.
M. Notani, H. Sakurai, N. Aoi, M. Hirai, H. Kobinata,
Y. Watanabe, T. Nakamura A. Yoshida, Y.
Watanabe, T. Kubo, T. Nakagawa, N. Inabe, H.
Kumagai, A. Goto, and M. Ishihara: "Search for
New Neutron Rich Nuclei Far from Stability (Z =10 rv 13)", ibid.
T. Suzuki: "Radii of Na Isotopes and a Neutron Skin" ,ibid.
T. Ichihara, M. Ishihara, H. Ohnuma, T. Niizeki,
T. Yamamoto, K. Katoh, T. Yamashita, Y. Hara,
Y. Fuchi, S. Kubono, M. H. Tanaka, H. Okamura,
S. Ishida, T. Uesaka, and Y. Satou: "Spin-Flipand Non-Spin-Flip Isovector Excitations Observed inthe ( 12 C,12N) Reactions at Ej A=135 MeV and the(13C, 13 N) Reactions at Ej A=100 MeV", ibid.
Y. S. Mochizuki, K. Oyamatsu, and T. Izuyama: "Nuclear Deformation Induced by Superfiuid Vortices Inside Neutron Stars and the Origin of Glitches", Fall
Meet. Astronomical Soc. Jpn., Niigata, Oct. (1995).
T. Kohno: "Current and Future Data Available inJapan" , Int. Workshop on Radiation Belts, Models
and Standards, Brussel, Belgium, Oct. (1995).
T. Nakamura, E. Kim, A. Konno, M. Imamura, N.
Nakao, T. Shibata, Y. Uwamino, N. Nakanishi,
Suo Tanaka, H. Nakashima, Sh. Tanaka, and M.
Baba: "Activation Cross Section Measurements using Quasi-Monoenergetic Neutron Field from 20 to150 MeV", OECDjNEA , 2nd Specialists' Meet. on
Shielding Aspects of Accelerators, Targets and Irradiation Facilities, CERN, Geneva, Switzerland, Oct.
(1995).
K. Oyamatsu: "Symmetry Energy at Subnuclear Densities and Its Implications on Unstable Nuclei andNon-spherical Nuclei in the Neutron-Star Crust",
RCNP Workshop on Relativistic Approaches in Nu278

clear Structure and Reactions, RCNP, Osaka, Nov.
(1995).
A. Mengoni: "Direct Radiative Capture Mechanisms
and the Structure of Light Nuclei", Ann. Meet. on
Nuclear Data, JAERI, T-okai, Nov. (1995).
T. Suzuki: "Radii of Sodium Isotopes", Invited talk at
Int. Chern. Congr., Hawaii, U.S.A., Dec. (1995).

3.

Atomic and solid-state physics

J. Z. Tang and I. Shimamura: "Calculations of Photodetachment from H- by the Hyperspherical CloseCoupling Method II", Fall Meet. Phys. Soc. Jpn.,
Shizuoka, Sept. (1994).
M. Kimura, I. Shimamura, and M. Inokuti: "Double
and Single Ionization of He and H2 by Slow Protons
and Antiprotons", US-Mexico Workshop on Atomic
Physics, San Juan del Rio, Mexico, Dec. (1994).
J. Z. Tang and I. Shimamura: "Resonances in the Photodetachment ofH-", Symp. on Atomic and Molecular Processes in the Space, Sagamihara, Dec. (1994).
I. Shimamura: "Recent Topics on the Theory of Antiprotonic Helium", 3rd RIKEN Symp. on the Theory of Atomic and Molecular Processes, Wako, Feb.
(1995).
Y. Kanai, Y. Nakai, T . Kambara, T. M. Kojima, M.
Oura, and Y. Awaya: "Impact Parameter Dependence of Double-Electron Capture Processes in LowEnergy Highly-Charge Ion Collisions", Symp. on the
Physics of Highly-Charged Ions, Tokyo, Feb. (1995).
B. DePaola: "Binary Encounter Electron Production
at Relativistic Collision Velocities", RIKEN Symp.
on Researchers on Solid State Physics and Materials, Atomic Physics, Nuclear Chemistry, Biologicaland Material Medical Sciences Using RIKEN Ring
Cyclotron VIII, Wako, Feb. (1995).
I. Shimamura: "Theory of Muon-Catalyzed Fusion",
Symp. on Elementary Atomic Processes for the Developments of Nuclear Reactors, Tokaimura, Mar.
(1995).
T. Yoshida, N. Jiang, and D. M. Schrader: "Chemi- cally Stable Compounds of Positions with Ordinary
Atoms and Molecules" , Meet. American Physical Society, Milwaukee, U.S.A., Mar. (1995).
I. Shimamura: "Recent Topics on Muon-Catalyzed
Fusion Theory", RIKEN Symp. on Muon Sciences'94jUTMSL Users' Meet., Wako, Mar. (1995).
Y. Awaya: "X-ray Emited by Electronic Transion in
Muonic Atoms", ibid.
T. Okada, Y. Noro, H. Kitazawa, Y. Kobayashi, and
F. Ambe: ,,61 Ni Mossbauer in Spinel Chromites II",
50th Meet. Phys. Soc. Jpn., Yokohama, Mar. (1995).
R. Kadono, A. Matsushita, R. M. Macrae, K.
Nishiyama, and K. Nagamine: "Muonium Centers
in Si and Ge under Photo-Excitation", ibid.
Q. Hui, J. L. Persson, M. Nakamura, and M. Takami:"Highly Excited Atoms in Liquid Helium", ibid.

T. Fujita, N. Nishimori, F. Wakamatsu, K. Maeda, H.
Akiyoshi , A. Motoshima, H. Nakamura, K. Sagara,
and T. Nakashima: "Production of Polarized Neutron Beam Around 12 MeV and Precise Determination of Polarization", ibid.
J. Z. Tang and I. Shimamura: "Calculation of Angular
Distribution of Photoelectrons from He", ibid.
J. Z. Tang: "One-Photon Double Ionization of He" ,ibid.
M. Kimura and I. Shimamura: "Difference in the
Mechanisms of Double Ionization by Low-Energy
Protons and Antiprotons", ibid.
Y. Bitoh, H. Suzuki, A. Itoh, M. Imai, N. Imanishi, Y.
Nakai, T. Kambara, Y. Kanai, T. M. Kojima, andY. Awaya: "Incident Ion Dependence of the Fragmentation of C 60 ", ibid.
M. Oura, Y. Itoh, T. Koizumi, T. M. Kojima, M.
Gonno, M. Sano, T. Sekioka, H. Yamaoka, N.
Watanabe, and Y. Awaya: "Ionization of Eu+ Ions
Due to 5p Photo excitations" , ibid.
H. Schmidt-Bocking: "He Double Ionization Investigated by Cold Target Recoil Ion Momentum Spectroscopy", ibid.
B. D. DePaola: "Experimental Absolute Charge Capture Cross Sections for Highly Charged Xenon on a
Rydberg Target", ibid.
I. Shimamura:"Cross Sections for Collisions ofMolecules with Subexcitation Electrons", Workshop on Electron Degradation Processes, Cambridge,
Massachusetts, U.S.A., Apr. (1995).
Y. Kanai, Y. Nakai , K. Soejima, T. M. Kojima, T.
Kambara, and Y. A waya: "Present Status and Future Plans of RIKEN 14.5 GHZ Caprice", 12th Int.
Workshop on ECR Ion Sources, Wako, Apr. (1995).
S.F.C.O ' Rourke, I. Shimamura, and D.S.F. Crothers:"CDW-EIS Recoil DCS for Single Ionization in
Proton-Helium Collisions", European Conf. on
Atomic and Molecular Physics, Edinburgh, U.K.,
Apr. (1995).
H. Kageyama, K. Kawatsura, R. Takahashi, S. Arai,
H. Takeshita, Y. Aoki, S. Yamamoto, P. GeoppeltLanger , H. Naramoto, T. Kambara, M. Oura, T.
Papp, Y. Kanai, Y. Awaya, H. Horino, Y. Mokuno,
and K. Fujii: "L X-ray Spectra of Fe and Cu by 0.75
MeV lu H , He, Si, and Ar Ion Impacts", 3rd Int.
Symp. on Swift Heavy Ions in Matter, Carn, France,
May (1995).
K. Sagara: "Precise Experiments on N-d Scatteringand Capture Reaction", Recent Progress in Nuclear
Reaction Study, Tokyo, May (1995).
H. Saitoh, K. Soejima, S. Kravis, K. Okuno, and N.
Kobayashi: "Single and Multiple Electron Capture
Cross Sections in Low-Energy Multiply Charged IonAtom Collisions", 1995 Joint Meet. on the Mass
Spectrometry, Hachioji, May (1995).
I. Shimamura and M. Kimura: "Molecular Theory of
Antiprotonic and Other Exotic Helium" , Int. Symp.

on Muon Catalyzed Fusion and Physics of Exotic
Atoms and Molecules, Dubna, Russia, June (1995).
M. Kimura and I. Shimamura: "Double and Single
Ionization of He and H2 by Proton and Antiproton
Impact", ibid.
A. Igarashi, T. Shirai, N. Toshima, and I. Shimamura:"M uon-Transfer Reaction dJ..L( n = 2) + t ---+ d +tJ..L(N = 2)", ibid.
Y. Nakai: "Fragmentation of C 60 in Fast Ion-C 6o Collision", YITP Symp. on the Similarity and Difference between Nuclei and Microclusters, Kyoto, June
(1995).
K. Kawatsura, H. Kageyama, R. Takahashi, Y. Nakai,
D. Hamaguchi, S. Arai, Y. Aoki, S. Yamamoto,
P. Goppelt-Langer, H. Takeshita, H. Naramoto, T.
Kambara, M. Oura, T. Papp, Y. Kanai, and Y.
Awaya: "L X-ray Emission Spectra of Fe and Cu Induced by Heavy Ions" , 4th TIARA Res. Rev. Meet.,Tokyo, June (1995).
J. Z. Tang and I. Shimamura: "Differential Cross
Sections for Photoionization of He", Int. Symp. on
Atomic and Molecular Dynamics in Photoionization,
Quebec, Canada, July (1995).
E. Vagi: "Channelling Study on the Behaviour of Kr
Atoms Implanted in Aluminium", 16th Int. Conf.
on Atomic Collisions in Solids, Linz, Austria, July
(1995).
M. Oura, Y. Awaya, M. Gonno, Y. Itoh, M. Kimura,
T. Koizumi, T. M. Kojima, M. Sano, T. Sekioka,
N. Watanabe, and H. Yamaoka: "Photoionizationof Eu+ in the Region of 5p Excitation", 19th Int.
Conf. on the Physics of Electronic and Atomic Collisions (XIX ICPEAC), Whistler, Canada, July- Aug.
(1995).
T. M. Kojima, Y. Awaya, M. Gonno, Y. Itoh, M.
Kimura, T. Koizumi, M. Oura, M. Sano, T. Sekioka,
N. Watanabe, and H. Yamaoka: "Photoionization of
Eu+ in the 4d Giant Resonance Region", ibid.
M. Sano, Y. Awaya, M. Gonno, Y. Itoh, T. Koizumi,
T. M. Kojima, S. D. Kravis, M. Oura, T. Sekioka,
N. Watanabe, and A. Yagishita: "Photoion Yield
Spectroscopy in the 4d Shell of Xe+", ibid.
T. Kambara, Y. Awaya, Y. Kanai, T. M. Kojima, Y.
Nakai, O. Jagutzki, V. Mergel, H. Schmidt-Baking,B. D. DePaola, J. Z. Tang, M. Kimura, and I.
Shimamura: "Momentum Distribution of Recoil Ions
from 8.7 MeV 07+ -He Collisions", ibid.
Y. Itoh, T. Koizumi, S. D. Kravis, M. Oura, M. Sano,
T. Sekioka, and Y. A waya: "Photoionization of Sr+
Ions in 3d Ionization Region", ibid.
M. Oura, Y. Awaya, M. Gonno, Y. Itoh, M. Kimura,
T. Koizumi, T. M. Kojima, M. Sano, T. Sekioka,
N. Watanabe, and H. Yamaoka: "Photoionization of
Eu + in the Region of 5p Excitation", ibid.
A. Igarashi: "Calculation of Ionization Cross Sections
in Positron-Hydrogen Scattering" , ibid.
J. Z. Tang and I. Shimamura: "Double Photoionization of He by the Hyperspherical Close-Coupling
279

Method", ibid.
J. Z. Tang and I. Shimamura: "Angular Distributionsof Photoelectrons from Helium" , ibid.
A. Itoh, Y. Bitoh, Y. Nakai, H. Suzuki, M. Umezawa,
M. Imai, N. Imanishi, T. Kambara, and Y. Awaya:"Projectile Dependence of C 6o -Fragmentation by the
Impacts of MeV Energy H, Li, C , Si, and Au Ions",
ibid.
Y. Nakai, A. Itoh, T. Kambara, Y. Bitoh, and Y.
Awaya: "Coincidence Measurement of Fragment
Ions with Final Charge State of Projectile Ion in Fast
Carbon Ion-C 6o Collision", ibid.
M. Kimura and I. Shimamura: "Double and Single
Ionization of H2 by Proton and Antiproton Impact
at 10 ke V", ibid.
J. F. McCann, I. Shimamura, and T. Watanabe:"Muon Capture by Helium and Molecular Hydrogen", ibid.
Y. Kino, M. R. Harston, I. Shimamura, E. A. G.
Armour, and M. Kamimura: "Normalization of the
Asymptotic Form of Three-Body (dtJ.L)+ and (ddJ.L)+
Wave Functions" , ibid.
S. F. O. 0' Rourke, I. Shimamura, and D. S. F.
Crothers: "CDW-EIS Recoil DCS for Single Ionization of Helium by Proton Impact" , ibid.
B. D. DePaola, M.-T. Huang, S. Winecki, M. P.
Stockli, Y. Kanai, S. R. Lundeen, C. W. Fehrebach,and S. A. Arko: "Absolute Cross Sections for Charge
Capture from Rydberg Targets by Slow Highly
Charged Ions", ibid.
B. D. DePaola, Y. Kanai, P. Richard, Y. Awaya, T.
Kambara, and Y. Nakai: "Binary Encounter Electron Production at Relativistic Collision Velocities" ,ibid.
K. Sagara, A. Motoshima, T. Fujita, H. Akiyoshi, N.
Nishimori, and K. Maeda: "A Blow-In Type Windowless Gas Target", Int. Nuc!. Phys. Conf. , Beijing,
China, Aug. (1995).
N. Nishimori, K. Sagara, T. Fujita, H. Akiyoshi, K.
Maeda, H. Nakamura, and T. Nakashima: "Production of Low-Energy Polarized Neutron Beam" , ibid.
J. Z. Tang and I. Shimamura: "Differential Cross Sections for Photoionization of He", 11th Int. Conf. on
Vacuum Ultraviolet Radiation Physics, Tokyo, Aug.
(1995).
T. Kambara, Y. Awaya, A. Igarashi, Y. Kanai, T. M.
Kojima, Y. Nakai, O. Jagutzki , V. Mergel, and H.
Schmidt-Bocking: "Electron Capture and Transfer
Ionization in 8.7 MeV 0 7 + - He Collisions", 14th
Int. Seminar on Ion-Atom Collisions, Seattle, U.S.A. ,Aug. (1995).
T. Koizumi, Y. Awaya, M. Gonno, Y. Itoh, M. Kimura,T. M. Kojima, S. Kravis, M. Oura, M. Sano, T.
Sekioka, N. Watanabe, H. Yamaoka, and F. Koike:"4d Photoionization of Singly-Charged Xe, Ba, andEu Ions", Int. Conf. on Vacuum Ultraviolet Radiation Physics, Tokyo, Aug. (1995).
280

I. Shimamura: "Exotic Atoms and Molecules", Meet.
of the Meson Science Association, Wako, Aug.
(1995).
R. Kadono, R. M. Macrae, A. Matsushita, K.
Nishiyama, and K. Nagamine: "Bistability of Muonium Centers in Crystalline Si and Ge Proved by
Photo-Induced J.LSR" , 9th Int. Conf. Hyperfine Interactions, Leuven, Belgium, Aug.- Sept. (1995).
Y. Kobayashi, T. Okada, Y. Noro, H. Kitazawa, and
F. Ambe: "Giant Magnetic Hyperfine Field of Ni 2+
Ions in Spinel Chromites" , 1995 Int. Conf. on Applications of Mossbauer Effect , Rimini, Italy, Sept.
(1995).
J. Nakamura, Y. Kobayashi, K. Asai , N. Yamada,and F. Ambe: "57 Fe Mossbauer Spectroscopy of
Fe1+xSb", ibid.
R. Kadono: "Bistability of Muonium Centers in Crystalline Si and Ge Probed by Photo-Induced J.LSR",
Invited Talk at the Autumn Meet. of the British
Radiofrequency Spectroscopy Group, Oxford, U.K. ,Sept. (1995).
K. Kawatsura, R. Takahashi, H. Kageyama, Y. Nakai,
D. Hamaguchi, A. Nishihata, S. Arai, T. Kambara,
M. Oura, T. Papp , Y. Kanai , Y. Awaya, Y. Aoki,
S. Yamamoto, H. Takeshita, P. Goppelt-Langer, H.
Naramoto, Y. Horino, Y. Mokuno, and K. Fujii:"Fine Structure of L X-Ray Emission Spectra of Fe
and Cu", 13th PIXE Symp. , Tokyo, Sept. (1995).
J. Z. Tang and I. Shimamura: "Hyperspherical CloseCoupling Approach to Single and Double Photoionization of Two-Electron Systems", Oji Int. Seminaron Atomic and Molecular Photoionization, Tsukuba
Sept. (1995).
N. Nishimori, K . Sagara, T. Fujita, F. Wakamatsu,
H. Akiyoshi, H. Nakamura, K. Maeda, and T.
Nakashima: "Precise Measurement of Analyzing
Powder of D(ii, n) Scattering at 12 MeV", 1995 Fall
Meet. Phys. Soc. Jpn. , Kasugai , Sept. (1995).
T . Okada, Y. Noro , H. Kitazawa, Y . Kobayashi , and
F. Ambe: "Relation between Hyperfine Magnetic
Field at 61Ni and Ligand Distortion", 1995 Fall Meet.
Phys. Soc. Jpn. , Sakai, Sept. (1995).
R. Kadono, R. F. Kieft , W . A. MacFarlane, and S. R.
Dunsiger: "Diffusion and Locallization of Muonium
in KCI:Na", ibid.
T. Okada, Y. Noro, H. Kitazawa, Y. Kobayashi , J.
Nakamura, and F. Ambe: "Magnetization and 61 Ni
Mossbauer on Spinel Rhodit es", ibid.
K. Ishii, Y. Kimura, T. Nishida, and K. Ando: "BeamFoil Spectra of Highly Charged Neon Ions", ibid.
K. Hamada, M. Ohsawa, E. Kajiro, W . G. Jin, H.
Uematsu, T. Minowa, and H. Katsuragawa: "Measurement of Isotope Shifts of Fe by Resonance Ionization Spectroscopy", ibid.
Q. Hui , J. L. Persson, M. Nakamura, and M. Takami:"LIF Spectra of Ag-He Complex in Liquid Helium",ibid.

M. Nakamura, J. L. Persson, Q. Hui, and M. Takami:"LIF Spectra of Ag-He Complex in Cold Helium
Gas", ibid.
T. Kambara: "Future Projects of RIKEN Accelerator
Research Facility", 19th Ann. Meet. of the Society
for Atomic Collision Research, Tokyo, Oct. (1994).
J. Z. Tang and I. Shimamura: "Photoionization of He
from an Excited State", Int. Workshop on Photoionization, San Francisco, U.S.A., Oct. (1994).
Y. Kobayashi, T. Okada, Y. Noro, H. Kitazawa, and F.
Ambe: ,,61 Ni Mossbauer Spectroscopy of Ni Oxides
with Spinel Structure", 39th Symp. Radiochemistry,Niigata, Oct. (1995).
Y. Kobayashi, Y. Yoshida, H. HaBlein, K . Yukihira, K.
Hayakawa, Y. Watanabe, A. Yoshida, T . Nakamura,
M. Ishihara, N. Inabe, M. Kase, A. Goto, Y. Yano,and F. Ambe: "Development of In-Beam Moss bauer
Spectroscopy at RALF" , ibid.
J. Z. Tang and I. Shimamura: "Hyperspherical CloseCoupling Approach to High-Lying Double Excited
States of He and H-", 5th Int. Workshop on Autoionization Phenomena in Atoms (AIS-95), Dubna,
Russia, Dec. (1995).
E. Yagi: "Perspectives of Accelerator-Using AnalysisRBS", 4th Nuc!. Res. Center of Univ. Tokyo Symp.,
Tokyo, Dec. (1995).
4.

Radiochemistry, radiation chemistry, and radiation biology

T. Abe, S. Yoshida, T. Sakamoto, T. Kameya, S.
Kitayama, N. Inabe, M. Kase, A. Goto, and Y.
Yano: "Is Irradiation of Heavy Ion Beams at Specific stages of the Fertilization Cycle of Plants Effective for Mutagenesis?", Japan-U.S.A. Workshop on
Modification of Gene Expression and Non-Mendelian
Inheritance, Tsukuba, Jan. (1995).
S. Yam ago , H. Tokuyama, E. Nakamura, K. Kikuchi,
K. Sueki, S. Kaneko, M. Nakahara, S. Enomoto, and
F. Ambe: "In Vivo Biological Behavior of WaterMiscible Fullerenes. 14C-Labeling, Absorption, Distribution, Excretion and Acute Toxicity" , 8th Symp.
of Fullerenes, Kyoto, Jan. (1995).
S. Enomoto, M. Yanaga, R. Hirunuma, K. Endo, S.
Ambe, and F. Ambe: "Bio-Trace Elemental Research Using the Multitracer Technique (1)", RIKEN
Symp. on Studies on Condensed Matter Physics,
Atomic Physics, Nuclear Chemistry, and Biology andMedicine Using RIKEN Ring Cyclotron VII, Wako,
Feb. (1995).
S. Enomoto and F. Ambe: "Study of Bio-Trace Element Using a Muon X-ray Technique", ibid.
M. Iwamoto, S. Ambe, S. Enomoto, H. Maeda, and
F. Ambe: "Preparation of a Multitracer by Heating
under a Reduced Pressure a Tin Target Irradiatedwith Heavy Ions", 69th Nat!. Meet. Chern. Soc. Jpn.
(Spring) , Kyoto, Mar. (1995).

A. Shinohara, S. Kiryu, K. Soga, T. Muroyama, M.
Furukawa, S. Kojima, Y. Ohkubo, F. Ambe, K.
Mukai, A. Yokoyama, T. Saito, and H. Baba: "Differential Recoil Ranges of Reaction Products in theCu+ 40 Ar, 14N Nuclear Reactions" , ibid.
M. Yanaga, S. Enomoto , K. Miyabayashi, R.
Hirunuma, K. Endo, S. Ambe, M. Tozawa, and F.
Ambe: "Study on Uptake and Distribution of Various Elements in Rats using the Multitracer Technique (3) Distribution and Behaviour of Trace Elements Produced from Au Target" , ibid.
M. Yanaga, R. Hirunuma, H. Minami, K. Endo, S.
Enomoto, S. Ambe, M. Tozawa, and F. Ambe:"Study on Uptake and Distribution of Various Elements in Rats using the Multitracer Technique (4)Distribution and Behaviour of Trace Elements Produced from Ge Target", ibid.
Y. Takahashi, Y. Minai, S. Ambe, S. Enomoto, M.
Iwamoto, H. Maeda, F . Ambe, and T. Tominaga:"Influence of Humic Acid on Adsorption of Ions on
Kaolinite or Silica Gel - Application of Multitracer
Technique-", ibid.
K. Mukai, A. Yokoyama, T. Saito, H. Baba, Y.
Ohkubo, A. Shinohara, and M. Furukawa: "Incomplete Fusion in the Intermediate Energy Region",
ibid.
T. Shinbnaga, S. Ambe, S. Enomoto, H. Maeda,
M. Iwamoto, T. Watanabe, and I. Yamaguchi:"The Absorption of Various Elements into Plant in
Atmosphere-Plant System, The Application of theMultitracer", ibid.
S. Ambe and F. Ambe: "Emission and Absorption
Mossbauer Spectra of Tin with Ligands from Silver
to Iodine" , ibid.
K. Endo, R. Hirunuma, M. Yanaga, M. Tozawa, S.
Enomoto, S. Ambe, and F. Ambe: "Behavior ofTrace Elements in Rats Using the Multitracer Technique (1) Absorption and Distribution of Trace Elements by Oral Administration", 115th Ann. Meet.
Pharm. Soc. Jpn., Sendai, Mar. (1995).
S. Enomoto, S. Ambe, F. Ambe, K. Endo, R.
Hirunuma, and M. Yanaga: "Behavior of Trace Elements in Rats Using the Multitracer Technique (2)Tissue Distribution of Trace Elements in Zinc Deficient Rats", ibid.
R. Hirunuma, K. Endo, M. Yanaga, S. Enomoto, S.
Ambe , and F. Ambe: "Behavior Trace Elements
in Rats Using the Multitracer Technique (3) Tissue
Distribution of Trace Elements in Vitamin D Overloaded Rats", ibid.
T. Ozaki, S. Enomoto, Y. Minai, S. Ambe, F. Ambe,and T. Tominaga: "Distribution of REE in Ferns",
12th Symp. on Rare Earth Element, Tokyo, May(1995).
Y. Takahashi, Y. Minai, S. Ambe, M. Iwamoto, S.
Enomoto, H. Maeda, N. Takematsu, F. Ambe, andT. Tominaga: "Evaluation of Environmental Behavior of Trace Metal Elements by Multitracer Tech281

nique: Influence of Humate Formation", 56th Conf.
Analytical Chemistry, Osaka, May (1995).
S. Enomoto, B. Liu, R. Amano, S. Ambe, and F.
Ambe: "Biodistribution of Rare Earth Elements in
Diabetes Model Mice 2", 4th Ann. Meet. of the Rare
Earth Soc. Jpn., Tokyo, May (1995).
S. Enomoto, M. Yanaga, R. Hirunuma, K. Endo, S.
Ambe, and F. Ambe: "Metabolism and Behaviourof Various Rare Earth Elements in Rats Using theMultitracer Technique", ibid.
F. Arribe: "The Multitracer", CHRT Forum'95 Tokyo,
Tokyo, May (1995).
T. Shinonaga, S. Ambe, S. Enomoto, H. Maeda, M.
Iwamoto, T. Watanabe, and I. Yamaguchi: "Multitracer Study on Behavior of Various Elements
in Atmosphere-Plant System", Int. Conf. on Isotopes'95, Beijing, China, May (1995).
S. Ambe, M. Iwamoto, H. Maeda, and F. Ambe: "Multitracer Study on Adsorption of Metal Ions on QFe203", ibid.
S. Enomoto, M. Yanaga, R. Hirunuma, K. Endo, S.
Ambe, and F. Ambe: "Multitracer Study on Distribution of Carrier-Free Radioactive Isotopes in Organs of Rats\', ibid.
Y. Takahashi, Y. Minai, T. Ozaki, S. Ambe, M.
Iwamoto, H. Maeda, F. Ambe, and T. Tominaga:"Multitracer Study on the Effect of Humate Formation .on the Adsorption Behavior of Metal Ions on
Kaolinite and Silica Gel", ibid.
S. Enomoto, S. Ambe, and F. Ambe: "Usefulness of
the Multitracer Technique in Research of Bio-Trace
Elements", 7th Symp. on Roles of Metals in Biological Reactions, Biology and Medicine, Hamamatsu,
June (1995).
S. Enomoto, R. Amano, S. Ambe, and F. Ambe:"Biobehavior of Various Rare Earth Elements in Diabetes Mellitus Mice", ibid.
R. Hirunuma, K. Endo, M. Yanaga, S. Enomoto, S.
Ambe, and F. Ambe: "Behavior of Various Trace
Elements in Vitamin D Overloaded Rats Using Multitracer Technique", ibid.
S. Enomoto, S. Ambe, and F. Ambe: "Significanceof the Bio-Trace Elemental Research in Metabolic
Physiology on Space Field: Metabolism in BioOrganisms on Non-Gravitational Field by Using
the Multitracer Technique", 12th Space Utilization
Symp., Tokyo, July (1995).
S. Ambe, R. Hirunuma, S. Enomoto, M. Yanaga, R.
Amano, K. Endo, and F. Ambe: "Radioactive Multitracer Technique for the Study of Trace Elements in
Rats and Mice", 5th COMTOX Symp. on Toxicology
and Clinical Chern. of Metals, Vancouver, Canada,
July (1995).
R. Hirunuma, K. Endo, M. Yanaga, S. Enomoto, S.
Ambe, and F. Ambe: "Study on Distribution ofTrace Elements in Vitamin D Overloaded Rats Using
the Multitracer Technique", ibid.
282

S. Enomoto, M. Yanaga, R. Hirunuma, K. Endo, S.
Ambe, and F. Ambe: "Distribution and Behaviorof Trace Elements in Zinc Defficient Rats Using theRadioactive Multitracer Technique", ibid.
H. Yasuda, S. Uchida, S. Ambe, B. Liu, H. Maeda, S.
Enomoto, and F. Ambe: "Distribution Coefficient
between Soil Solid and Liquid Phase Obtained byMultitracer Technique", 32nd Ann. Meet. on Radioisotopes in the Physical Sciences and Industries,
Tokyo, July (1995).
T. Ozaki, S. Enomoto, Y. Minai, S. Ambe, F. Ambe,and T. Tominaga: "Study on Accumulation of Lanthanides in Dryopteris erythrosora by Multitracer
Technique", ibid.
Y. Takahashi, Y. Minai, S. Ambe, M. Iwamoto, H.
Maeda, F. Ambe, and T. Tominaga: "Multitracer
Study on Distribution of Metal Ions between Solidand Aqueous Phases in the Environment", ibid.
Y. Itoh, T. Kakizaki, K. Tanaka, A. Goto, N.
Nakanishi, M. Kase, N. Oshima, T. Suzuki, I.
Kanazawa, T. N akajyo, and Y. Ito: "Slow Positron
Production using RIKEN AVF Cyclotron II", ibid.
B. Liu, S. Ambe, S. Enomoto, and F. Ambe: "Application of Radioactive Multitracer to the Study ofLabelling of Antibody", ibid.
T. Watanabe, K. Matsumoto, S. Ambe, and I.
Yamaguchi: "Translocation of Radionuclides fromPlant Leaf Surfaces", ibid.
T. Kakizaki, Y. Itoh, K. H. Lee, K. Tanaka, A.
Goto, N. Nakanishi, M. Kase , and Y. Ito: "Generation of Slow Positron Beam from Short Lifetime Positron Emitters" ,56th Meet. Jpn. Soc. Appl.
Phys., Kanazawa, Aug. (1995).
K. Eguchi-Kasai: "Radiation Quality and the Relationship among Cellular Radiosensitivity, DNA Repair and RBE", 10th Int. Natl. Congr. Radiat. Res.,
Wuerzburg, Germany, Aug. (1995).
F. Ambe: "Multitracer-A Versatile Tracer Technique
Developed from Heavy Ion Physics", 2nd Int. Symp.
on Heavy Ion Physics and Its Applications, Lanzhou,
China, Aug. (1995).
y. Yanagida, J. Nakamura, K. Asai, N. Yamada, Y.
Ohkubo, S. Ambe, T. Okada, F. Ambe, and S.
Uehara, and Y. Kawase: "Studies on Structural
Phase Transition of Barium-Ruthenium Metal Oxides by 117In_ TDPAC", 10th Int. Conf. on Hyperfine
Interactions, Leuven, Belgium, Aug.- Sept. (1995).
K. Tanaka, Y. Itoh, K. H. Lee, T. Kakizaki, A. Goto,
N. Nakanishi, M. Kase , and Y. Ito: "Development of
the Targets for Online Spin-Polarized Slow Positron
Beam", 1995 Fall Meet. Phys. Soc. Jpn., Sakai, Sept.
(1995).
M. Iwata, S. Ambe, Y. lijima, M. Iwamoto, H. Maeda,
and F. Ambe: "Study of Adsorption of Metal Ionson Q-Fe203 Using a Multitracer", 39th Symp. on
Radiochemistry, Shizuoka, Sept. (1995).
R. Hirunuma, S. Enomoto, M. Yanaga, R. Amano,
K. Endo, B. Liu, S. Ambe, and F. Ambe: "Multi-

tracer Studies of Behavior of Trace Elements in Rats
and Mice" , 7th Int. Conf. on Bioinorganic Chemistry,
Lubeck, Germany, Sept. (1995).
S. Enomoto, B. Liu, R. G. Weginwar, R. Amano, S.
Ambe, and F. Ambe: "In Vivo Behavior of Various
Rare Earth Elements in Lipogenous Diabetes Model
Mice by Using the Multitracer Technique", ibid.
T. Ozaki, S. Enomoto, Y. Minai, S. Ambe, F. Ambe,and T. Tominaga: "Determination of Lanthanides
and Other Trace Elements in Ferns by Instrumental Activation Analysis", 9th Int. Conf. on Modern
Trends in Activation Analysis, Seoul, Korea, Sept.
(1995).
Y. Okamoto, S. Enomoto, and R. Hirashima: "Try to
Make a Gamma Camera Using Cooled CCD", Jpn.
Soc. Nucl. Med., 35th Ann. Meet., Yokohama, Oct.
(1995).
T. Abe, T. Sakamoto, S. Kumata, T. Torashima, andS. Yoshida: "New Mutation Method using SpecificStages of the Fertilization Cycle of Plants" , 30th
Ann. Meet. Soc. Chern. Regul. Plants, Utsunomiya,Oct. (1995).
N. Ito, I. Kunugiyama, A. Iwatsuki, M. Ito, S. Ambe,
S. Enomoto, and F. Ambe: "Masurement of Potassium, Rubidium and Cesium Inft.ux Rate into Erythrocyte using Multitracer Technique", 39th Symp.
on Radiochemistry, Niigata, Oct. (1995).
K. Mukai, A. Yokoyama, T. Saito, H. Baba, Y.
Ohkubo, S. Kiryu, C. Murata, T. Muroyama, A.
Shinohara, and M. Furukawa: "Heavy-Ion Reactions
for the 14N+1 65 Ho and the 40 Ar+141 Pr Systems at
Intermediate Energies", ibid.
A. Shinohara, S. Kiryu, K. Mukai, T. Muroyama, J.
Kurachi, S. Kojima, T. Saito, A. Yokoyama, Y.
Ohkubo, M. Furukawa, and F. Ambe: "Angular Distribution of Fission Fragments in the Heavy-Ion Reaction of Gold in the Intermediate Energy Range" ,ibid.
B. Liu, S. Ambe, S. Enomoto, H. Maeda, R. Weginwar,
and F. Ambe: "Group Separation of a Multitracer from a Gold Target Irradiated by High-Energy
Heavy Ions", ibid.
R. G . Weginwar, Y. Kobayashi, S. Ambe, B. Liu, S.
Enomoto, and F. Ambe: "Separation of a Multitracer from an Au Target Irradiated by Heavy Ions" ,ibid.
B. Liu, S. Enomoto, S. Ambe, and F. Ambe: "Biodistribution Study of Antibodies Labelled with Multitracer in Mice", ibid.
A. Sekiguchi, N. Ito, N. Furusato, Y. Saito, K. Kimura,
H. Maeda, S. Ambe, and F. Ambe: "Studies on
the Ion Exchange Adsorption Behavior of Strongly
Acidic Resin Nation and its Application to Analytical Chemistry", ibid.
S. Enomoto, B. Liu, R. G. Weginwar, H. Maeda, S.
Ambe, and F. Ambe: "Physiological and Biochemical Investigations of Bio-Trace Elements in Various
Disease Model Animals", ibid.

T. Ozaki, S. Enomoto, Y. Minai, S. Ambe, F. Ambe,and T. Tominaga: "Activation Analysis Study onDistribution of Trace Elements in Ferns" , ibid.
R. Hirunuma, K. Endo, S. Enomoto, M. Yanaga, B.
Liu, S. Ambe, and F. Ambe: "Distribution of Trace
Elements in Vitamin D Overloaded Rats Using theMultitracer Techniques", ibid.
M. Yanaga, R. Endo, S. Enomoto, R. Hirunuma, B.
Liu, K. Endo , S. Ambe, M. Tozawa, H. Nakahara,
and F. Ambe: "Application of the Multitracer Technique for a Study on Distribution of Trace Elements,
in LEC Rats" , ibid.
M. Yanaga, R. Yamamoto, S. Enomoto, S.
Futatsugawa, R. Hirunuma, K. Endo, M. Tozawa,and F. Ambe: "Determination of Trace Elements
in Organs of Rats by PIXE and Neutron Activation
Analysis" , ibid.
H. Sasaki, F. Yatagai, Y. Furusawa, T. Kanai. F.
Hanaoka, and W. G. Zhu: "Dependence of Interphase Cell-Death Induction on LET Values of Accelerated Heavy-Ions", 38th Ann. Meet. Jpn. Radiation
Res. Soc., Chiba, Nov. (1995).
S. Kitayama, K. Narumi, M. Kikuchi, and H.
Watanabe: "Construction of Cosmid Library of
Deinococcus radiodurans", ibid.
I. N arumi, H. Watanabe, A. B. M. M. Hossain, A.
Tanaka, and S. Kitayama: "Cloning and Base Sequence of Radiation Induced Catarase of Deinococcus radiodurans", ibid.
Y. Minai, Y. Takahashi, T. Ozaki, S. Enomoto, S.
Abe, B. Liu, F. Ambe, and T. Tominaga: "Multitracer Study on the Environmental Behavior of Trace
Elements", 1995 Ann. Meet. Geochem. Soc. Jpn.,
Shimizu, Nov. (1995).
Y. Takahashi, Y. Minai, S. Ambe, H. Maeda, F. Ambe,and T. Tominaga: "Formation of Humate Complexes
with Various Metal Ions -Application of Multitracer
Technique", 11th Meet. on Humic Substances, Tokai,
Nov. (1995).
K. Narumi, H. Watanabe, and S. Kitayama: "Comparative Studies of Thermotolerance of RecA Proteins of
Deinococcous and Thermus" , 18th Ann. Meet. Jpn.
Mol. BioI. Soc., Nagoya, Dec. (1995).
A. Yokoyama, K. Mukai, K. Takesako, T. Saito, H.
Baba, Y. Ohkubo, A. Shinohara, and M. Furukawa:"Recoil Properties of the Products in the Heavy-Ion
Reactions at Intermediate Energy" , 1995 Int. Chern.
Congr. Pacific. Basin Soc., Honolulu, U.S.A., Dec.
(1995).

5.

Material analysis

K. Maeda: "Application of Particle Induced X-Ray
Emission (PIXE) to Liquid Samples", 62nd Spring
Meet. Electrochemical Soc. Jpn., Tokyo, Apr. (1995).
N. Arai, Y. Nagata, W. Sakamoto, K. Maeda, andK. Yoshida: "Correlation between Trace Elements283

in Red Sea Bream Otoliths and Ambient Temperature" , 1995 Spring Meet. Jpn. Soc. Fish. Sci., Tokyo,
Apr. (1995).
N. Arai, W. Sakamoto, and K. Maeda: "An Attempt
to Analyze Fish Otoliths by In-Air PIXE" , 7th Int.
PIXE Conf., Padova, Italy, May (1995).
H. Hamanaka, K. Hasegawa, and K. Maeda: "Study ofSample Charging Effects on Satellite Peaks by Meansof High Resolution PIXE", ibid.
J. Kawai, K. Maeda, N. Sakauchi, and I. Konishi:"Strong X-Ray Emission Due to Electrification",
ibid.
M. Kumagai and M. Iwaki: "Luminescence of Ah03
Implanted with Rare Earth Element (IV)", 56th Autumn Meet. Jpn. Soc. Appl. Phys. , Nonoichi, Aug.
(1995).

284

J. Kawai, S. Hayakawa, Y. Kitajima, K. Maeda, and
Y. Gohshi: "Total Reflection X-Ray Photoelectron
Spectroscopy of Ag", 1995 Fall Meet. Phys. Soc.
Jpn., Sakai, Sept. (1995).
Y. Ikeda, N. Arai , W. Sakamoto, T. Murayama, K.
Maeda, and K. Yoshida: "Trace Element Analysis ofJapanese Common Squid Statoliths", 1995 Autumn
Meet. Jpn. Soc. Fish. Sci., Kyoto, Sept. (1995).
Y. Ikeda, N. Arai, W. Sakamoto, T. Murayama, K.
Maeda, and K. Yoshida: "Trace Elemental Analysis of Hard Tissues of Marine Lives: In the Case ofSquids", 13th PIXE Symp., Tokyo, Sept. (1995).
N. Arai, N. Takai, W. Sakamoto, K. Yoshida, and K.
Maeda: "Trace Elemental Analysis of Fish OtolithsIII", ibid.

x. LIST OF SYMPOSIA(Jan.- Dec. 1995)
1) Structure Functions of Nucleons and Nuclei
17- 18 Jan., Wako, RIKEN, Cyclotron Lab.
2) 8th Symp. on Solid State Physics and Materials, Atomic Physics, Nuclear Chemistry, and Biology andMedicine Using RIKEN Ring Cyclotron
6 Feb., Wako, RIKEN, Muon Science Lab., Atomic Physics Lab., Nuclear Chemistry Lab., and Cellular
Physiology Lab.
3) Theory of Atomic and Molecular Processes III
17-18 Feb., Wako, RIKEN, Atomic Physics Lab.
4) Muon Science '94
6- 7 Mar., Wako, RIKEN, Muon Science Lab.
5) Application of Nuclear Hyperfine Techniques to Physics and Chemistry '95
22 Mar., Wako, RIKEN, Nuclear Chemistry Lab.
6) Recent Progress at RIKEN Accelerator Facility
23- 24 Mar., Wako, RIKEN, Linear Accelerator Lab.
7) 2nd RIKENjINFN Joint Symp. on Perspectives in Heavy-Ion Physics
22- 26 May, Wako, RIKEN, Radiation Lab.
8) Int. Symp. on Molecular Mechanisms of Mutation Induction
12-14 July, Tokyo, Cellular Physiology Lab. and Radioisotope Technology Div.
9) Symp. on Radiation Protection at RIKEN RI Beam Factory
8 Sept., Wako, RIKEN , Safety Center, Cyclotron Lab., and Radioisotope Technology Div.
10) Electron Scattering and Unstable Nuclei
1 Dec., Wako, RIKEN, Linear Accelerator Lab.
11) Basics and Application of Spin-Polarized Positron Beam
14 Dec. , Wako, RIKEN, Nuclear Chemistry Lab.
12) Spin Structure of the Nucleon
18- 19 Dec. , Wako, RIKEN, Radiation Lab. and Cyclotron Lab.
13) Structure of Medium and Heavy Nuclei
26- 27 Dec., Wako, RIKEN, Cyclotron Lab. and Radiation Lab.

285

XI. LIST OF SEMINARS(Jan.- Dec. 1995)

Radiation Lab., Cyclotron Lab., andLinear Accelerator Lab.
1) K. Takayanagi, Tokyo Denki University (Saitama), 20 Jan.
"Response Function in Extended RPA Theory"
2) N. Ohnishi, University of Tokyo (Tokyo), 30 Jan.
"Magnetization of Ferromagnetic Clusters"3) K. Sugawara-Tanabe, Otsuma Women's University (Tokyo), 13 Feb.
"M1 Transitions and Resurrection of LS-Couplingin Superdeformation"14) S. Ozaki, Brookhaven(U.S.A.), 1 June
"On the RHIC Project"

National

Laboratory15) G. Munzenberg, GSI (Germany), 5 June
"The Heaviest Elements 110 and 111: Results andFuture Experiments"16) R. Warner, Oberlin College (U.S.A.), 12 June
"Proton Halo in 8B? Reaction Cross Sections of
It and Other Light Nuclei"17) X. Ji, MIT (U.S.A.), 20 June
"Theoretical Aspects of RHIC Spin Physics"4) l. T. Cheon, Yonsei University (Korea), 15 Feb.
"Physical Phenomena in Limited Space"18) N. Dikansky, Novosibirsk (Russia), 26 June
"Collective Phenomena in Electron Cooling"5) M. Tomizawa, INS (Tokyo), 31 Mar.
"On the IH Linac at INS"

19) C. Samanta, Saha Institute of Nuclear Physics(India), 26 June
"Deuteron Breakup at Extreme Forward Angle:
Evidence of Coulomb Dissociation?"

6) H. Sato, RIKEN (Saitama), 10 Apr.
"Systematics of Alpha Q-value: Potential Dependence of Alpha Decay Life Time"
7) S. Kuyucak, Australian National University (Australia), 21 Apr.
"High-Spin States in Boson Models with Applications to Actinide Nuclei"8) A. Ono, RIKEN (Saitama), 24 Apr.
"Heavy Ion Reactions Studied with Antisymmetrized Molecular Dynamics"
9) Yuko S. Mochizuki, RIKEN (Saitama), 8 May"Nuclear Lattice Deformation Inside NeutronStars and the Origin of Pulsar Glitches"10) A. Mengoni, RIKEN (Saitama), 9 May"The Direct Radiative Capture Process and theHalo Structure of Nuclear Excited States"11) M. Hara, RIKEN (Nishi-Harima), 10 May"RF System of SPring-8"12) R. G. Lovas, Institute of Nuclear Research of the
Hungarian Academy of Sciences (Hungary), 15
May"Antisymmetrization in Cluster Decay"13) Valery V. Burov, Bogoliubov Laboratory ofTheoretical Physics (Russia), 31 May"Hadron Form Factors in Relativistic Harmonic
Oscillator Model"
28620) M. Okamura, RIKEN (Saitama), 29 June
"Siberian Snake at RHIC"
21) Z. Yizhong, Institute of Atomic Energy (China),
10 July"Some Aspects of Relativistic Heavy Ion Collisions by Including Delta Degrees of Freedom"
22) A. Goto, RIKEN (Saitama), 14 July
"Review of Beam Orbit Simulations for the RARF
Accelerators"
23) T. Watanabe, INS (Tokyo), 19 July
"Profile Beam Monitor and Orbit Correction at
TARN II"
24) H. Kunz, University of Mainz (Germany) , 19 July
"Optical Isotope Shift and Hyperfine Structure
Measurements at Fission Isomers"25) D. H. Wilkinson, Sussex University (U.K.), 24
July"Structure of the Nucleon"
26) R. Nagaoka, Sincrotrone Trieste (Italy), 1 Aug.
"Commissioning and Operation of ELETTRA"
27) H. D . Luc, Institute of Nuclear Science and Technique Vietnam Atomic Energy Commission (Vietnam), 9 Aug.
"On the Accelerators in Vietnam"28) T. Suda, Tohoku University (Sendai), 9 Aug.
"Recent Results of the 3He( e,e'7r) Measurement at
MAMI, MAINZ"
29) M. Honma, Aizu University (Fukushima), 21
Aug.
"Quantum Montecarlo Diagonalization Method in
Nuclei and Its Application"30) J. S. Chai, KAERI (Korea), 22 Aug.
"Status of KAERI AVF Cyclotron""Proton Beam Energy Measurement of KAERI
Cyclotron at 25.89 MHz"

31) H. Backe, Institute fuer Kernphysik (Germany),
30 Aug.
"X-ray Radiation from a Low Emittance 855 MeVElectron Beam"
32)

J.-Y. Zhang, Institute of Modern Physics (China),
4 Sept.

"Tilted Cranking Model: TAC Solutions in OddOdd Nuclei"33) K. Varga, ATOMKI (Hungary), 7 Sept.
"Precise Solution of Few-Body Problems with
Stochastic Variational Method on Correlated
Gaussian Basis"40) K. Kumar, Tennessee Technological University(U.S.A.), 6 Oct.
"Semiclassical Field Theory of Fundamental Interactions"41) E. Ormand, University of Tennessee (U.S.A.), 16
Oct.
"Nuclear Structure at the Proton-Drip Line:Some Things to Do with Radioactive Beams"
42)

D. A. Kosower, Service de Physique Theorique,Centre d'Etudes de Saclay (France), 19 Oct.
"Cutting and Sewing One-Loop Amplitudes in
QCD"

43)

D. A. Kosower, Service de Physique Theorique,Centre d'Etudes de Saclay (France), 24 Oct.
"Physics with Jets"

44) T. Nakatsukasa,
Chalk River Laboratory(Canada), 6 Nov.
"Rotational Alignment, Breakdown and Damping of Octupole Vibrations in Rapidly Rotating
Nuclei"45)

S. Watanabe, INS (Tokyo), 7 Nov.
"DCCT for Power Supply of Magnet"

34) A. Bonasera, INFN, Catania (Italy) , 11 Sept.
"Quantum Dynamics in Phase Space"46) D. Dean, Oak Ridge National Laboratory(U.S.A.), 10 Nov.
"Shell Model Monte Carlo Studies of Nuclei"35) M. Przyrembel, University of Mainz (Germany),
13 Sept.
"The Mainz Neutrino Mass Experiment"47) M. Borden, Los Alamos (U.S.A.), 13 Nov.
"Introduction to the Los Alamos Neutron Science
Center"36) Q . Shen, Shanghai Institute of Nuclear Research,
Chinese Academy of Science (China), 18 Sept.
"Research on 40 Ar + 27 Al Collision below 100
MeV lu: Experimental Results and BUU, QMD
Calculations; Azimuthal Distribution and Reaction Plane Dispersion for 84Kr + 197 Au Reaction
at E Lab I A between 35 and 400 Me V I u"48) Y. D. Devi, RIKEN (Saitama), 14 Nov.
"N ew Signature for g-Bosons in the Magnetic
Dipole Strength Distribution of Odd Mass Nuclei"37)

M. Tomizawa, INS (Tokyo), 20 Sept.
"Variable Frequency IH Linac for RIKEN RI
Beam Factory"

38) L. Westerberg, The Svedberg Laboratory in Uppsala (Sweden), 21 Sept.
"An Overview of Experimental Programs, theGustaf Werner Synchro Cyclotron and the CELSIUS Storage Ring, at The Svedberg Laboratory
in Uppsala"39)

K. Ikeda, Niigata University (Niigata), 2 Oct.
"Structure of Bound and Resonance States ofLight Nuclei Far from Stability"49) V. Yu. Denisov , Institute for Nuclear Research,
Kiev (Ukraine), 20 Nov.
"Giant Resonances in a Semiclassical Approximation"50) K. Kaki, Shizuoka University (Shizuoka), 4 Dec.
"Relativistic Impulse Approximation for NucleonNucleus Elastic Scattering"51) T. Udagawa, University of Texas (U.S.A.), 5 Dec.
"Longitudinal and Transverse Spin Response in
the Gap and Delta Resonance Regions"52) R. Seki, The California Institute of Technology(U.S.A.), 12 Dec.
"Effects of Nuclear Correlation on High-Energy"287

Atomic Physics Lab.

1) T. Aberg, Helsinki Univ. Tech. (Finland) , 13 Jan.
"Electron Capture by Strong Dynamic Electromagnetic Fields""Detection of Defects in Semiconductors by
Mossbauer Spectroscopy and PAC"
3) M. Kojima, Washington Univ. (U.S.A .), 19 Sept.
"Diamonds, Noble Gas and Geohistory"

2) J. H. McGuire, Tulane Univ. (U.S.A.) , 1 Mar.
"Dynamics of Matter, Antimatter and Light Interacting with Atoms, Molecules and Solids"4) M. Katayama, Univ. Osaka Pref. , 27 Sept.
"Arsenic Metabolism in Living Cells"3) H. Shiromaru, Dept. Phys., Tokyo Metrop. Univ.
(Tokyo) , 16 Mar.
"Molecular Coulomb Explosion"5) M. Hasegawa, Tohoku Univ. , 9 Nov.
"Study on Defect and its Electron Structure of Si
and Si0 2 Glasses by Means of Positron Annihilation"4) A. M. Ermolaev, Univ. Durham (U.K .), 16 Mar.
"Some Theoretical Studies Suggested by the Current Program of JET Experiments (Oxford)"
5) J.-P. Connerade, Imperial College (U.K.) , 8 Sept.
"Giant Resonances in Atomic Photoionization"6) Yu. N. Demkov, St. Petersburg Univ. (Russia), 19
Sept.
"Different Aspects of the Exchange Processes"7) M. Zhan, The Chinese Academy of Sciences(China) , 8 Dec.
"Coherent Control of Molecular Motions by
Laser"
Nuclear Chemistry Lab.

1) R. G. Weginwar, College of Engineering, Chandrapur (India) , 8 June
"Trace Elemental Determination in Biological andEnvironmental Samples by Neutron Activation
Analysis"2) R. Sielemann, Hahn-Meitner-Institut Berlin (Germany), 19 July

288

Seminars on Physics at the RI Beam Factory1) I. Tanihata, RIKEN (Saitama) , 17 May"The RI Beam Factory Project, Present Status"
2) M. Uno, Ministry of Education, Science, Sports
and Culture (Tokyo) , 5 June
"Mass Formulas in the Region of Unstable Nuclei"
3) H. Izumi, Tokyo Inst. Tech. (Tokyo) , 23 Oct.
"Measurement of Deformation Parameter for Unstable Nuclei by Means of Spin-Aligned Radioactive Beam"
4) N. Aoi, Univ. TokyojRIKEN (TokyojSaitama),
13 Nov.
"Beta-Decay of Nuclei Very Far from the StabilityLine"5) T. Suzuki, Nihon Univ. (Tokyo), 13 Nov.
"Comments upon Effects of Halo on Beta-Decay"6) A. Korsheninnikov, RIKEN (Saitama) , 4 Dec.
"Measurements under Inverse Kinematical Conditions with Radioactive Beams"

XII. LIST OF PERSONNELRIKEN Accelerator Research Facility
ISHIHARA Masayasu
1* if ~ (Facility Director)
AWAYA Yohko ~ ~ ?§. -f- (Vice Facility Director)
YANO Yasushige -!R lff q; li (Vice Facility Director)n-Linac Division
CHIBA Toshiya =f ~ ~rJ EX
IKEZAWA Eiji it11. iR1t
KOHARA Shigeo /J'\ Nt li X

HEMMI Masatake ~ Jt jJ)( ~KASE Masayuki 110 ~ l§ Z.
MIYAZAWA Yoshitoshi '8 iR {£ $~*1

Ring Cyclotron Division
FUJITA Jiro iii ill
1!B
IKEGAMI Kumio it11.1:1L -==~KAGEYAMA Tadashi J~ LiJ if
KASE Masayuki 110 ~ l§ Z.
KUBO Toshiyuki 7-.. f* $~ ¥NAKAGAWA Takahide 9=t ill :q: ~o KUN 0 Hiroki ~ lff JA

GOTO Akira f& iii ~ * 1
INABE Naohito fIB Jl1 Mj A
KAMIGAITO Osamu 1:j:][7H~~
KOHARA Shigeo /J'\ Nt li X
NAGASE Makoto -If ~ 4l£
OGIWARA Kiyoshi W<. 1*
YOKOYAMA Ichiro ;f1Ii LiJ ~ 1!~

Experimental Support Division
ICHIHARA Takashi
Nt !j!
KAN AI Yasuyuki ~ 1t 1* Z.
KUMAGAI Hidekazu ft~:fr ~ fD
MORITA Kosuke ~ ill H5- fr
WATANABE Yasushi ill ~KAMBARA Tadashi i!jJ Nt iE * 1
KOBAYASHI Toshio /J'\{~it
MATS-UZAKI Teiichiro ~~1J!m1!~
OKUBO Yoshitaka *~f*gr.Q
YATAGAI Fumio :frillft>cx

Radioisotope Facilities Division
AMBE Fumitoshi q;:g~)( $~*1
KOBAYASHI Yoshio /J'\ ~'*~IWAMOTO Masako

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FUJITA Shin iii ill ~JT
NAKANISHI Noriyoshi 9=t gg

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NAKAJIMA Shunji 9=t 5ij ~¥UWAMINO Yoshitomo 1: Jl:

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NAKAMURA Toshiko 9=t~t t l-fYOSHIDA Tohru "6 ill 11&*2

NUMATA Shigeo

Steering Committee
AMBE Fumitoshi q;:g~)( $~AWAYA Yohko ~ ~ ?§. -=tHANAOKA Fumio 1t. IiYiI )( it
IN 0 UE Yorinao 1=r 1: fI ill
KAMBARA Tadashi i!jJ Nt iE
KOBAYASHI Toshio /J'\;t* {~ it
MATSUOKA Masaru ~ IiYiI MJMIYAZAWA Yoshitoshi '8 iR {£ $~TAKAMI Michio r.Q ~ :i!t 1::
YAGI Eiichi )\5R ~YOSHIDA Shigeo "6 ill a ~AONO Masakazu W lff if fD
GOTO Akira f& iii ~INAMURA Takashi T. fIB ~t !j!
ISHIHARA Masayasu
1* if ~KATSUMATA Koichi Jm.x *11: ~KUMAGAI Noritaka ft~:fr: ~ :q:
MATSUZAKI Teiichiro ~~fJ!m1!B
NAG AMINE Kanetada 7]( ~ ~ ,?;!,TANIHATA Isao :fr m ~ ::;k*3
YANO Yasushige -!R lff 17: li**1 Group Leader,*2 Manager,n-*3 Chairperson289

Scientific and Engineering Personnel

Cosmic Radiation Laboratory
KATO Hiroshi 1m.. tw:

KOHNO Tsuyoshi

iPJ ff~(Visitors)
HASEBE Nobuyuki *~$ffirr (Fac. Gen. Educ., Ehime Univ.)
KASHIWAGI Toshisuke f8
llJ 11'- (Fac. Eng., Kanagawa Univ.)
KATO Chihiro 110" =f ~ (Fac. Sci., Shinshu Univ.)
MUNAKATA Kazuoki
fl- ~ (Fac. Sci. , Shinshu Univ.)
MURAKAMI Hiroyuki :f1" J:. ~ Z (Fac. Sci., Rikkyo Univ.)
NAGATA Katsuaki 71<. IE JjJ tlJI (Fac. Eng., Tamagawa Univ.)
NAKAMOTO Atsushi 9='
i~(Fac. Sci., Rikkyo Univ.)
YANAGIMACHI Tomoki fgp lilT M W (Fac. Sci., Rikkyo Univ.)

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(Students)
ITO Tomoyuki #t .. M 11- (Fac. Sci. Eng., Waseda Univ.)
ITSUMI Norifumi Ji Jt ~ ~ (Fac. Sci. Eng., Waseda Univ.)
SHINO Tomoaki ~ ~ ~ (Fac. Sci. Eng., Waseda Univ.)
YAMAGIWA Iwao LiJ ~ .. (Grad. Sch. Sci. Eng. , Saitama Univ.)=

Cyclotron Laboratory
FUJITA Jiro .. B3
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GOTO Akira 1:&" ~*1
INABE Naohito tffi ill MJ A
JIN Wei-Guo ~ ~ If!
KAMIGAITO Osamu J:.j:!H1·f~­
KATAYAMA Takeshi It LiJ it PJ*2
KOHARA Shigeo /J\ rnt £ X
MORITA Kosuke ~ B3 ~~ 11'NAKAGAWA Takahide 9=' }II ~ ~NAKANISHI Noriyoshi 9=' g§o KUN 0 Hiroki ~ ff Jt:. W
OTSUKA Takaharu±j( ~ ra*2
SUGANUMA Hideo 1f m~ X
UESAKA Tomohiro J:.!,& tx i-¥=YAMAJI Shuhei LiJ ~ ff~ .:qz.*1
YOKAYAMA Ichiro ~ LiJ - JlB**1 Senior Scientist,*c **2 Senior Visiting Scientist,

FUJITA Shin Ki B3 'fJT
IKEGAMI Kumio HQ.J:.1L ~ISHIDA Satoru ~ B3 '/%KAGEYAMA Tadashi J3 LiJ iE
KASE Masayuki 110 ~ l§ Z
KITAGAWA Hisashi ~t }I/
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KUBO Toshiyuki 7-.. f* fit ¥NAGASE Makoto
ifi IDOC
NAKAJIMA Shunji 9=' ~ ~1
OG IWARA Kiyoshi ~ rnt mONO Akira /J\ ff •PU Yuehu nw ~ J1E
SUZUKI Toshio jft
fit ~ *2
WAKASUGI Masanori :;ff ~ l§ 1!@
YANO Yasushige fX ff
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ABE Yasuhisa /»iT -:g~ ~ 7-.. (Yukawa Inst. Theor. Phys., Kyoto Univ.)
AKUTSU Takao /»iT7-..~f%x (NASDA)
PJ t!~(NASDA)AOKI Jiro W
ARAI Eiichi 'fJT 1t 5R (Res. Lab. Nucl. React., T. I. T.)
ARAKAWA Kazuo m}I/ ~D X (JAERI, Takasaki)
BABA Shinji .~ j:~ ffi;}{ (NASDA)
BATYGIN Yuri
(Elect. Phys. Dept., Moscow Eng. Phys. Inst. , Russia)
CHA Shin i~ J! (Peking Univ. , China)
DATE Schin #t jl 1$ (JASRI)
DEY Ranadhir(Variable Energy Cycl. Cent.)
EJIRI Hiroyasu ~I fft~(Fac. Sci., Osaka Univ.)
EN'YO Hideto ~ l:j ~ A (Fac. Sci. , Kyoto Univ.)
FUJIOKA Manabu .. WiJ ~ (Cyclotron Radioisot. Cent., Tohoku Univ.)
FUJISAWA Takashi Ki ift rWJ i0 (Denki Kogyo Co. Ltd.)

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FUJISHIMA Shiro »i 8'b ~ f!B (I. H. I.)
FUJITA Yoshitaka »i 83 fE ~ (Fac. Sci., Osaka Univ.)
FUJIWARA Mamoru »i Im ~ (RCNP, Osaka Univ.)
FUKUDA Mitsuhiro ti B3 -Yt(JAERI, Takasaki)
FUKUMOTO Sadayoshi ti
tt ~ (KEK)
FURUNO Kohei t5!f:ft. 1f (Tandem Accel. Cent., Univ. Tsukuba)
FUTAMI Yasuyuki
Jt fflt Z (N.I.R.S.)
HADA Takashi 3J3J m r.'D ~ (NASDA)
HAM A Hiroyuki ~ J1;. ¥(I.M.S.)
HARADA Yuu rnt m ~!k (Sapporo Gakuin Univ.)
HASHIMOTO Osamu ~¥S (Inst. Nucl. Study, Univ. Tokyo)
HATANAKA Kichiji ~ q:.
(RCNP, Osaka Univ.)
HATSUKAWA Yuichi)1/ it (JAERI, Tokai)
HATTORI Toshiyuki m~ $ 13t ¥(Res. Lab. Nucl. React., T.I.T.)
HAYANO Ryugo 1f!.!f f~ 3i (Fac. Sci., Univ. Tokyo)
HEIGUCHI Kazuhiko 1f IJ ~O ~ (Sch. Medicine, Niigata Univ.)
HIES Markus G.
(Dept. Phys., Mainz Univ., Germany)
HIRAO Yasuo 1f If:. ~ ~ (N.I.R.S)(Former Staff of RIKEN)HIRASAWA Shokichi 1f iR if.
HONMA Mitio:@: it(Aizu Univ.)
HONMA Toshihiro~ J1;.
(Cyclotron Radioisot. Cent., Tohoku Univ.)
HORIBATA Takatoshi t)ffi!INti ~ 13t (Fac. Eng., Aomori Univ.)
HORIGUCHI Takayoshi ;t)ffi IJ ~ ~ (Fac. Sci., Hiroshima Univ.)
HORIUCHI Hisashi ;t)ffi pq 7N! (Fac. Sci., Kyoto Univ.)
HOSONO Kazuhiko *m!f ~D ~ (RCNP, Osaka Univ.)
IGARASHI Toshio 1i i\.$tit (NASDA)
IKEDA Akitu HI? 83 f)(~! (Shizuoka Inst. Sci. & Tech.)
IKEDA Nobuo HI? m 1$ ~ (Inst. Nucl. Study, Univ. Tokyo)
IKEDA Kiyomi HI?
~(Fac. Sci., Niigata Univ.)
IKEZOE Hiroshi HI? ~ tw: (JAERI, Tokai)
IMAI Kenichi A,~(Fac. Sci., Kyoto Univ.)
IMAMURA Mineo A,:fj *= it (Inst. Nucl. Study, Univ. Tokyo)
1:. {§ (Inst. Chern. Res., Kyoto Univ.)
INOUE Makoto
ISHII Takayuki ;fj~ ¥(NASDA)ISHIZUKA Takeo ;fj:l:* it ~ (Fac. Sci., Saitama Univ.)
Bg (JAERI, Tokai)
IWAMOTO Akira :E
IWASHITA Yoshihisa :E P 7j'!A. (Inst. Chern. Res., Kyoto Univ.)
IZUMOTO Toshiaki jJt~IJ itt(ColI. Sci., Rikkyo Univ.)
JEONG S. C.
(Inst. Nucl. Study, Univ. Tokyo)
JIN Wei-Guo 1ft ~ 00 (Fac. Sci., Tohou Univ.)
JYAN Donshin ~I fl J!. (Peking Univ., China)
KAMIMURA Masayasu 1:.:fj if. fflt (Fac. Sci., Kyushu Univ.)
KANAZAWA Mitsutaka 1ft iR Jt ~~ (N.I.R.S.)
KANMURI Tetsuo Jrt :g ~ (Fac. Sci., Osaka Univ.)
KANNO Toru 1f!f 11& (NASDA)
KATAYAMA Ichiro h LiJ - f!B (Inst. Nucl. Study, Univ. Tokyo)
KATAYAMA Takeshi h LiJ it P] (Inst. Nucl. Study, Univ. Tokyo)
KATO Kiyoshi 110 »i ~ 7j' (Fac. Sci., Hokkaido Univ.)
KATO Shohei 110 »i l§ 1f (Fac. Sci., Osaka Univ.)
KATORI Kenji 1m JfJ. ~(Fac. Sci., Osaka Univ.)
KATSURAGAWA Hidetsugu t£ )1/ ~ ooPJ (Fac. Sci., Tohou Univ.)
KAWAGUCHI Hideo )1/ IJ ~ X (Tokyo Denshi Co., Ltd.)KAWAGUCHI Takeo )1/ IJ JEt ~ (Mitsubishi Electric Co., Ltd.)KAWAI Mitsuji iiiJ ~ Jt ~ (Fac. Sci., Kyushu Univ.)
KITAGAWA Hisashi ~t )1/
r.'D (Inst. Phys., Univ. Tsukuba)
KOHAMA Akihisa /J\ it ~$ ~ (Fac. Sci., Univ. Tokyo)
KOHMOTO Toshiro iilJ$t f!B (Fac. Sci., Kyoto Univ.)
KONDO Michiya ;ill »i :@: -tf! (RCNP, Osaka Univ.)

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KOSAKO Toshiso /J'\1~it$x;ff (Atomic Energy Res. Cent., Univ. Tokyo)
KOTAJIMA Hisaya itB3~~'6JG (Fac. Eng., Tohoku Univ.)
KUBOYAMA Satoshi ~1:*LlJ?§tPJ (NASDA)
KUDO Hisaaki I Hi ~ ag (Fac. Sci., Niigata Univ.)
LEE Kong Ok
rnt.n (Rika Women's College)
LEE Sang Mul§(Inst. Phys., Univ. Tsukuba)
LIN Ching-Liang
iff: (Taiwan Univ., People's Republic of China)
MAEDA Kazuhide frj ffI fD ~ (Fac. Sci., Kyushu Univ.)
MARUMORI Toshio n ~ 1if -X (Fac. Sci. Tech., Sci. Univ. Tokyo)
MATSUDA Sumio ;.ffi- B3 *~ -X (NASDA)
MATSUI Yoshiko ;.ffi7J T (Fac. Tech., Tokyo Univ. Agr. Tech.)
MATSUKI Seishi ;.ffifiE j: (Inst. Chern. Res., Kyoto Univ.)
MATSUSE Takehiro ;.ffi- iii !1:: t.5- (Dept. Phys., Shinshu Univ.)(Fac. Sci., Kyoto Univ.)
MATSUYANAGI Kenichi ;.ffi- lPP liJf MATSUZAKI Kazuhiro ;.ffi- ~ - t.5- (NASDA)
MIAKE Yasuo .:::: I3JJ *.a~ (Inst. Phys., Univ. Tsukuba)
MIDORIKAWA Shoichi ~ Jrl • (Fac. Eng., Aomori Univ.)
MINAMISONO Tadanori i¥J III ,~, J'!IJ (Fac. Sci., Osaka Univ.)
MITSUMOTO Toshinori !£f~ ~(Sumitomo Heavy Industries, Ltd.)MIURA Iwao .:::: i-m !fi (RCNP, Osaka Univ.)
MIYAMURA Osamu g ~1' 1~ (Dept. Phys., Hiroshima Univ.)
MIYATAKE Hiroari g ~ ~ -m (Fac. Sci., Osaka Univ.)
MIZOTA Takeshi Wt B3 ~ ~ (Inst. Phys. , Univ. Tsukuba)
MIZUNO Yoshiyuki 7jc ff ~ Z(RCNP, Osaka Univ.)
MIZUSAKI Takahiro 7jc ~ JWJ t.5- (Fac. Sci., Univ. Tokyo)
MOCHIKI Kouiti M=:¥ (Dept. Phys., Musashi Inst. Technol.)
MORI Yoshiharu ~ ~ til (Inst. Nucl. Study, Univ. Tokyo)
MUKHOPADHTAY M.
(Variable Energy Cycl. Cent., India)
MURAKAMI Tetsuya ~1' J:. ~ -m (Fac. Sci., Kyoto Univ.)
MURAYAMA Toshiyuki ~1' LlJ ~IJ:¥ (Tokyo Univ. Mercantile Marine)
MUROTANI Shin £ ~ -c.I (Sch. Sci. & Eng., Waseda Univ.)
MUTO Kazuo JEt Hi - it (Fac. Sci., T.I.T.)
NAGAI Yasuki 71<~ 1M(Fac. Sci., T.I.T.)
NAITO Ichiro I1'J Hi - .M
(NASDA)
NAKADA Hitoshi I{l B3 t
(Coll. Art & Sci., Chiba Univ.)
NAKAHARA Hiromichi I{l5.L:if! (Fac. Sci., Tokyo Metrop. Univ.)t.5(KEK)NAKAI Koji I{l(NASDA)
NAKAJIMA Masato I{l ~ J{ A
Z (Fac. Sci., Kyushu Univ.)
NAKAMURA Hiroyuki I{l ~1'
NAKAMURA Masao I{l ~1' JE -X (NASDA)
NAKAMURA Ichiro I{l ~t m.a~ (Fac. Sci., Saitama Univ.)
NAKAMURA Takashi I{l ~t ~ PJ (Cyclotron Radioisot. Cent., Tohoku Univ.)
NAKAO Noriaki I{l ~ tm 13~ (lnst. Nucl. Study,' Univ. Tokyo)
NEMOTO Norio fH~(NASDA)(Sch. Sci. & Eng., Waseda Univ.)
NIIMURA Masanobu *JT ~1' lE(Inst. Chern. Res., Kyoto, Univ.)
NODA Akira !f B3 •NODA Kouji ff B3 fJI: PJ (N.I.R.S.)NOMURA Toru ff ~t 7
(Inst. Nucl. Study, Univ. Tokyo)
OGAWA Kengo /J'\ JJI 1!l.:g. (Fac. Educat., Chiba Univ.)
OHIRA Hideharu
1fl ~(NASDA)OKAMURA Hiroyuki fMJ ~1' 5.L Z (Fac. Sci., Univ. Tokyo)
OKAMURA Masahiro fMJ l1' l§ 5.L (Fac. Sci., T.I.T.)
OKUMURA Susumu ~ ~t :i1§ (JAERI, Takasaki)
ONISHI Naokig§ il[ ~~ (ColI. Art Sci., Univ. Tokyo)
OOKAWA Tomohiro
Jrl ~ 7.i (Mitsubishi Heavy Industries)
OSUGA Toshiaki ,*~Jf~$xI3JJ (ColI. Art & Sci., Chiba Univ.)OTSUKI Tsutomu *:#1 fJJ (Lab. Nucl. Sci., Tohoku Univ.)
OURA Akio
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QUAN Zhuo-Shu ~W (ColI. Eng., Hosei Univ.)
ROA Yi Nong
(Inst. Modern Phys., Academia Sinica, China)
SAGARA Kenji ~§ II ~ ~ (Fac. Sci., Kyushu Univ.)
SAKAI Hideyuki j!:It ~ 11- (Fac. Sci., Univ. Tokyo)
SAKATA Fumihiko ~ m X ffi (Inst. Nucl. Study, Univ. Tokyo)
SATO Kenichi fti: iii ~ (Dept. Phys., Tohoku ColI. Pharm.)
SATO Kenji fti: Hlll;)( (N.I.R.S.)
SATO Yukio f~ iii ¥ ~ (N.I.R.S.)
SEBE Takashi iii {iB q: (ColI. Eng., Hosei Univ.)
SEKINE Hirotaka ~ t~ ~ ~i: (Former Staff of RIKEN)SEKINE Toshiaki ~ fN {~aJI (JAERI, Tokai)
SHIBATA Tokushi ~ m ~ ,~\ (Inst. Nucl. Study, Univ. Tokyo)
SHIKAZONO Naoki
III OC ~ (JAERI, Tokai)
SHIMANO Yousuke II{~ ff ~$ 1r- (NASDA)
SHIMIZU Akira fit 71< ag (RCNP, Osaka Univ.)
SHIMOMURA Koichiro r:ttH~'-1!B (Meson Sci. Lab., KEK Brunch, Univ. Tokyo)
SHIN Kazuo ~ fO ~ (Fac. Eng., Kyoto Univ.)
SHIN Seung Ai~(Rika Women's ColI.)
SHINOZUKA Tsutomu 1il ±j( ~ (Cyclotron Radioisot. Cent., Tohoku Univ.)
SHIRAI Toshiyuki B:It!U:X Z (Yukawa Inst. Theor. Phys., Kyoto Univ.)
SUEKI Keisuke=* N 1r- (Fac. Sci. , Tokyo Metrop. Univ.)
SUGAIIsao 'if:lt Wk (Inst. Nucl. Study, Univ. Tokyo)
SUGIYAMA Hiroki ~ LlI
W (NASDA)SUMIYOSHI Hiroyuki 1t 5" rt. 11- (Matsusho-Gakuen Junior Coll.)
SUZUKI Toshio ~ =*!U:X ~ (Fac. Eng., Fukui Univ.)
SUZUKI Toshio ~ft =* {~~ (Coll. Sci. Tech., Nihon Univ.)
TAGISHI Yoshihiro m J¥ tit(Tandem Accel. Cent., Univ. Tsukuba)
TAJIMA Naoki m IIJ.~ ill W (CoIL Art Sci., U niv. Tokyo)
TAKANAKA Masao fob iqt 1& fil (INS. , Univ. Tokyo)
TAKEMASA Tadashi ~ 1& jf' ± (Kyoto Univ. Education)rt. (JAERI, Tokai)
TAKEUCHI Suehiro tt pq
TAKIGAWA Noboru ~ )1/ ¥l- (Fac. Sci., Tohoku Univ.)
TAMAGAKI Ryozo 3i tg II --= (Fac. Sci., Kyoto Univ.)
TAMURA Takashi m:tt fob ~ (NASDA)
TAN ABE Kazuko m ill fO -f- (Otsuma Women's Coll.)(Inst. Nucl. Study, Univ. Tokyo)
TANAKA Jinichi m 9=t t
TANAKA Kazuhiro
9=t fO J1l{ (Fac. Sci., Hiroshima Univ.)
TANAKA Yasushi
9=t 1* ~ (Kyokuto Boeki Kaisha, Ltd.)TANIKAWA Masashi :a- )1/ MJ ~ (Fac. Sci., Univ. Tokyo)
TOHYAMA Mitsuru J! LlI ~iMJ (Kyorin Univ.)
TOMIMASU Takio ~~ $%~ (FEL Res. Inst. Inc.)TOMINAKA Toshiharu ~ 9=t *IJ ~il (Hitachi, Ltd.)TOMITANI Takehiro ~:a- ~ (ii (N.I.R.S.)
TOMIZAWA Masato ~ ~~ iE A (lnst. Nucl. Study, Univ. Tokyo)
TOMOTA Toshiaki 1X m!U:X. (Fac. Eng. , Aomori Univ.)
TORIYAMA Tamotsu ,~LlI 1* (Dept. Phys., Musashi Inst. Technol.)
TSUNEMOTO Hiroshi {!i 5G tf (N.I.R.S.)
UESUGI Masato J::. ~ iE A (NASDA)UTSUNOMIYA Hiroaki *:tB8~. (Fac. Sci., Konan Univ.)
UWAMINO Yoshitomo J::.:it tit 111'1 (lnst. Nucl. Study, Univ. Tokyo)
WADA Michiharu fO m ~il (Inst. Nucl. Study, Univ. Tokyo)
WADA Ryoiti fO m II (Texas A & M Univ., U.S.A.)
WADA Takahiro fD~i:(Fac. Sci., Konan Univ.)(Fac. ScL, Osaka Univ.)
WAKAI Masamichi ;s: 1f iE
WAKUTA Yoshihisa fO?-.m.?-. (Fac. Eng., Kyushu Univ.)
WATANABE Shiniti at ill f$ (Inst. Nucl. Study, Univ. Tokyo)
WEI Baowen ~ ~ X (Inst. Modern Phys., Academia Sinica, China)

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XIA Jiawen ][ {t)( (Inst. Modern Phys., Academia Sinica, China)
YABANA Kazuo j( it. - ta- (Fac. Sci., Niigata Univ.)
YAMADA Taiichi LlJ ill ~ (ColI. Eng., Kanto Gakuin Univ.)
YAMANOUCHI Mikio LlJ jAJ ~ it (Inst. Phys., Univ. Tsukuba)
YAMAZAKI Takashi W ~ ~ (RCNP, Osaka Univ.)(Lab. Nucl. Sci., Tohoku Univ.)
YAMAZAKI Hirohito LlJ ~ )l t
YE Feng lIt(Inst. Modern Phys., Academia Sinica, China)
YOSHIDA Nobuaki 5 EB
(Fac. ScL, Univ. Tokyo)
YOSHIDA Shiro 5 EB 1Ff!!,.M (Dept. Phys., Ishinomaki Senshu Univ.)
YOSHINAGA Naotaka 5 71< Nij q: (Fac. Sci., Saitama Univ.)ru. (NASDA)YOSHIOKA Yasuhiro 5 Itn]f[](Fac. Eng., Kyushu Univ.)
YOSHIZAWA Yasukazu 5 iR
YUAN You-Jin(Inst. Modern Phys., Academia Sinica, China)
ZHANG Li ~ JL (Inst. Modern Phys., Academia Sinica, China)

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(Students)
AKABORI Taisuke iffi:tjffi ~ :f;tj (Dept. Phys., Musashi Institute of Technology)
AKAZAWA Takashi iffi $... (Fac. Sci., Saitama Univ.)
AKIYOSHI Hiromiti f}( 5 ~ % (Fac. Sci., Kyushu Univ.)
AOKI Yuka W
IE W (Lab. Nucl. Sci., Tohoku Univ.)
ARIGA Takehiro tf ~ -mr tf (Fac. Sci., Saitama Univ.)
FUJITA Ken iii EB !It (Fac. ScL, Kyushu Univ.)
FUTAMI Yasuyuki~
Z (Inst. Phys., Univ. Tsukuba)
HONJYOU Yoshio *:lJ& ~ ~ (Inst. Phys., Univ. Tsukuba)
HONMA Hiroyuki
r"" m Z (Fac. Sci. , T.I.T.)
ITAGAKI Shohei ~& j:l[ m.If (Fac. Sci., Saitama Univ.)
KANGYO Yoshitsugu r& 11' ~ ffiJPJ (ColI. Sci., Chuo Univ.)(Fac. Sci., Tohoku Univ.)
KIM Eun Ju(Dept. Phys., Musashi Inst. Technol.)
KURATOMI Kouiti ~ g ru. KURIHARA Kaori ~ Nt W (Inst. Phys. , Univ. Tsukuba)
KURITA Tetsuro ~ EEl 'gf.M (Inst. Sci., Univ. Tsukuba)
KUROSAWA Tadahiro ~ iR ,r~, ru. (Fac. Sci., Tohoku Univ.)
LIU Xin(Peking Univ., China)
Z (Fac. Sci., Konan Univ.)
MABUCHI Hideyuki ,~7*l1
MATSUMOTO Norihiro~ ~~(Fac. Sci., Konan Univ.)
MIURA Takashi -:::: Hi(Inst. Phys., Univ. Tsukuba)
NAKAGAWA Keiko q:t }II JM, -t- (Fac. Sci., Tohoku Univ.)
NISHIMORI Nobuyuki Iffi ~ 18 11' (Fac. Sci., Kyushu Univ.)ODA Ayato ~ ill ~ A (Tokyo Univ. Mercantile Marine)
01 Makito *it7i*,c.A (ColI. Art Sci., Univ. Tokyo)
ONO Shinji /J . . ff '~= (Fac. Eng., Kyoto Univ.)OOTUKA Takahiro±j(rt. (Dept. Phys., Musashi Inst. Technol.)
OZAWA Shuiti /J . . ~~ f~ (ColI. Sci., Rikkyo Univ.)RYU Shin(Inst. Phys., Univ. Tsukuba)
SA SAHARA Takafumi i!f Nt q:)( (ColI. Sci., Chuo Univ.)
SASAKI Reiji ft~**t (Fac. Sci., Tohoku Univ.)
ff .if;@ (Fac. Sci., T.I.T.)
SEINO Satoshi
TAGAYA Yu $1Jn~(Fac. Sci., Univ. Tokyo)
TOMITA Shigeo &; EEl nX: ~ (Inst. Phys., Univ. Tsukuba)
TOMOHISA Yasuhiko 1X 7-.1* ~ (Inst. Phys., Univ. Tsukuba)
UTIYAMA Koji jAJ w ta- it- (Fac. Sci., Saitmam Univ.)
WAKAMATU Fumihiko ;s:~(Fac. Sci. , Kyushu Univ.)
it- (Fac. Sci., Toho Univ.)WAKUI Takashi i~ it~(Fac. ScL, Konan Univ.)
YAMAGAMI Munetaka LlJ 1:
YAMASHITA Ayako LlJl'"¥.j(-f- (Fac. Sci., Toho Univ.)
YODA Tetsuhiko it( EEl 'gf ~ (Lab. Nucl. Sci., Tohoku Univ.)
YUKI Hideyuki *Ei:lJ& ~ 11' (Fac. Sci., Tohoku Univ.)

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294

Linear Accelerator Laboratory
CHIBA Toshiya =f ~ llJ MG
FUKUDA Moichi
IE Lt _*1
IKEZAWA Eiji j.t!! iR
KASE Masayuki 110 ~ If!lJ :;t
KORSHENINNIKOV Alexei
MIYAZAWA Yoshitoshi g iR.13~ fit
MOMOTA Sadao EflEftc$1::*1
OZAWA Akira /J\ iR ~j
SUZUKI Takeshi ~~~TONUMA Tadao pi iB lE it
YOSHIDA Koichi "5 B3 1[. -

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FU JIMAKI Masaki Hi ~ lE fit
HEMMI Masatake ~ Jt iIX JEt
ITO Sachiko #t iii 1~ --1-*1
KOBAYASHI Toshio /J\{~ it*2
KUMAGAI Hidekazu n~:£- ~ lD
MOCHIZUKI Yuko ~}=] tl --1-*1
OGAWA Yoko /J\ )11 ~-'F -f-*1
SUGAHARA Yuichi "if ffii it _*3
TANIHATA Isao :£- iHl ~ -X*4
YANOKURA Minoru *!f~ ~***1 Special Postdoctoral Researcher, *2 Senior Scientist, *3 Postdoctoral Researcher,*4 Chief Scientist(Visitors)(Kurchatov Inst., Russia)
ALEKSANDROV D. V.
ARATANI Michi m:£- ~ 19 (Inst. Enviromental Sci.)
BOLBOT Michael D.
(Notre Dame Univ., U.S.A.)
BOYD Richard(Ohio State Univ., U.S.A.)
BROCKMANN Rolf (Inst. Phys., Univ. Mainz, Germany)(CTA, Inst. Estudos Avancados, Brasil)
CARLSON Brett
CHLOUPEK Frank(Ohio State Univ., U.S.A.)
DEMYANOVA AHa S.
(Kurchatov Inst. Atomic Energy, Russia)
FUJIWARA Mamoru iii ffii ~ (RCNP, Osaka Univ.)
FURUYA Keiichi 15:£-.I (Fac. Sci., Sci. Univ. Tokyo)
HONG Wang i~ jG (Fac. Sci., Univ. Tokyo)
ITO Noriaki #t iii l! ag (Dept. Cryst. Mater., Nagoya Univ.)
IZUYAMA Takeo {fI"liLiJftil-x (Dept. Phys., Toho Univ.)
KANAZAWA Kenichi ~ ~~ ftil (KEK)
KATORI Kenji 1& Jtt ~(Fac. Sci., Osaka Univ.)
KIKUCHI Jun *J?-tl! JllJi (Sci. Eng. Res. Lab., Waseda Univ.)
KIMURA Kikuo *~;f* ~it (Fac. Eng., Nagasaki Inst. Appl. Sci.)
KOLATA James(Notre Dame Univ., U.S.A.)
MATSUTA Kensaku$ ftil ~ (Fac. Sci., Osaka Univ.)
Itn] 1$ 1T (Res. Cent. Nucl. Phys., Osaka Univ.)
MATUOKA Nobuyuki
MOCHIZUKI Keiko ~}=].I -f- (Fac. Sci., Osaka Univ.)
MURAOKA Mitsuo ~t Itn] :J't ~ (ColI. Arts Sci., Chiba Univ.)
NIKOLSKI Evgenini Y.
(Kurchatov Inst., Russia)
NOJIRI Yoichi !f ffL ~-'F (Fac. Sci., Osaka Univ.)
OGAWA Kengo /J\)II!it:g. (ColI. Arts Sci., Chiba Univ.)
OGLOBLIN Alexei A.
(Kurchatov Inst., Russia)
OJIMA Minoru /J\ (IJ.~ ~ (Fac. Sci., Osaka Univ.)
OMATA Kazuo /J\ f~ lo -X (Inst. Nucl. Study, Univ. Tokyo)
lO ta- (Dept. Energy Eng. Sci., Nagoya Univ.)
OYAMATSU Kazuhiro ~PETRASCU Horia(Inst. Phys. Nucl. Eng., Romania)
PETRASCU Marius(Inst. Phys. Nucl. Eng., Romania)(Ohio State Univ., U.S.A.)RAIMANN Gerhard
SAGAWA Hiroyuki ftc )11 ~.L. ¥(Fac. Sci., Univ. Tokyo)
1T (Fac. Sci., Univ. Tokyo)
SAKAI Hideyuki i~
SATO Kazuhiro ftc iii fO J1;. (Tokyo Fire Dept.)
SUDA Toshimi ~~ IE llJ ~ (Fac. Sci., Tohoku Univ.)
SUGAWARA Masahiko "if rnt If!lJ If; (Fundam. Sci., Chiba Inst. Technol.)~ Z(Fac. Sci., Niigata Univ.)
SUZUKI Yasuyuki ~~TOKI Hiroshi ± rIji t.w: (Fac. Sci., Tokyo Metrop. Univ.)(Inst. Nucl. Res. Hungarian Acad. Sci., Hungary)
VARGA Kalman
WADA Takahiro fO IE ~.i 7.i (Osaka Dentist Univ.)

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295

m

YAMAGUCHI Hiromi t1J IJ~(Sci. Eng. Res. Lab., Waseda Univ.)ZAHAR Mohamed(Dept. Phys. , Notre Dame Univ. , U.S.A.)(Students)
HARADA Akihiko ~ EEl ag ~ (Fac. Sci., Osaka Univ.)
IZUMIKAWA Takuji 7~)1/.!$i P) (Fac. Sci. , Osaka Univ.)
KANOU Kenji Ilt ~ ts (Fac. Sci., Univ. Tsukuba)
KIUCHI Hiroshi(Fac. Sci. , Saitama Univ.)(Fac. Sci. , Sci. Univ. Tokyo)
MATSUSHITA Kenichi ~ r ~ MIHARA Mototsugu ~ ~ ~ RQPJ (Fac. Sci. , Osaka Univ.)·MIKI Keitarou ~*tjt*.M (Fac. Sci. , Konan Univ.)~
11& (Fac. Sci., Osaka Univ.)
MIYAKE Toru
MIYAMOTO Shinya g
J{. EJ(; (Fac. Sci. , Tokyo Metrop. Univ.)
NAKAZATO Masahisa 9=t 1l J{.:A. (Fac. Sci., Osaka Univ.)g§(Fac. Sci., Osaka Univ.)
ONISHI Takashi
IDiX (Fac. Sci. , Osaka Univ.)
SASAKI Makoto f1:~
SHIMOOKA Masaaki r [tUJ iE IljJ (Fac. Sci. , Kyoto Univ.)
TANIGAKI Minoru :tt:l:g ~ (Fac. Sci. , Osaka Univ.)
YAMAGUCHI Takayuki t1J lJ ... L (Fac. Sci. , Osaka Univ.)

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Radiation Laboratory
FUKUNISHI Nobuhisag§ ~ NOGONO Yasuyuki ~ II ~ Z*2
ICHIHARA Takashi~.!$i
IMAI Kenichi ~J! _*2IZUMO Koichi lli ~ 1t MENGONI Alberto*5
OKAMURA Masahiro IMJ ~1 l§
SAKURAI Hiroyoshi W! 1t tw: 1i
TENDOW Yoshihiko ~ jj! 7J ~YOSHIDA Atsushi 6 EE ~)r:

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GAl Moshe*1
HAHN Kevin I. *3
IDEGUCHI Eiji
lJ,*tsISHIHARA Masayasu ;fi ~ iE ~*4
KISHIDA Takashi j¥ EE ~.i
N OTANI Masahiro !f:B- ~~ JA
SAITO Naohito jf Jfi Ll A *3
TALMllgal*1
WATANABE Yasushi Vi jl ~*-¥*1 Eminent Scientist, *2 Senior Visiting Scientist , *3 Special Postdoctoral Researcher,*4 Chief Scientist, *5 Visiting Researcher(Visitors)
ABE Yasuhisa IlliJ {ft3 ~:A. (Yukawa Inst. for Theoretical Phys., Kyoto Univ.)
ADACHI Minoru JE j[ Jf (Fac. Sci. , Tokyo Inst. Technol.)
ANDO Yoshiaki !i Jfi ~ 1ft (CoIl. Sci. , Rikkyo Univ.)
ASAHI Koichiro :h!!. fJ!:-.eB (Fac. Sci., Tokyo Inst. Technol.)
BECK F. A.
(Groupe RSN , Strasbourg, France)
BROGLIA R.
(Univ. Milano & INFN , Italy)
CASTEN Rick(Phys. Dept. , Brookhaven Natl. Lab., U.S.A.)
DEVI Yelamanchili Durga(Saha Inst. Nucl. Phys. , India)
DOOI Makoto ~J{. (Univ. Tsukuba)
ENYO Hideto ~ l} ~ A (Fac. Sci., Kyoto Univ.)
FLOCARD Hubert(Division de Physique Theorique, Inst. Phys. Nucl., Orsay, France)
FUCHI Yoshihide mrJ ff ~ (Inst. Nucl. Study, Univ. Tokyo)
FUJIOKA Manabu Jfi [tUJ ~ (Cyclotron and Radioisot. Center, Tohoku Univ.)
FUKUDA Mitsunori 1i EE :JIt ilia (Fac. Sci. , Osaka Univ.)
FUKUDA Tomokazu
EE ~ fD (Inst. Nucl. Study, Univ. Tokyo)
FURUTAKA Kazuyoshi E raJ fD tJ{ (JAERI)
HAMAGAKI Hideki ~:l:g ~(Inst. Nucl. Study, Univ. Tokyo)
HASEGAWA Takeo :ff:tt)IIJl\:K (Fac. Eng., Miyazaki Univ.)
HATSUDA Tetsuo ;fJJ EE g ~ (Univ. Tsukuba)
HAYASHI Naoki *~ ill[
(School Sci., Nagoya Univ.)
HOSAKA Masahito 1*:I:JX *t A (Inst. Nucl. Study, Univ. Tokyo)

*

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m

m

296

*

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ICHIMURA Munetakef't it (ColI. Arts and Sci. , Univ. Tokyo)
IEKI Kazuo
fD -X (ColI. Sci., Rikkyo Univ.)
KASAGI Jirota 1i*~a1!B* (Lab. Nucl. Sci. , Tohoku Univ.)
KATAYAMA Ichiro h W - 1!B (Inst. Nucl. Study, Univ. Tokyo)
KATO Seigo 110 Hi ~:g. (Fac. Ed., Yamagata Univ.)
KATORI Kenji 1& Jf;{ ~(Fac. Sci. , Osaka Univ.)
KAWAKAMI Hirokane )11 L
1ft (Inst. Nucl. Study, Univ. Tokyo)
KAWASHIMA Hideo )I[ ~ ~ it (Inst. Nucl. Study, Univ. Tokyo)
KIM Jong Chan
(Dept. Phys. , Seoul Natl. Univ. , Korea)
KITAO Kensuke %$~~1Jh (Data Engineering Inc.)
KOIKE Yuji /j'\ j-t!!.
P1 (Niigata Univ.)
KOSOWER David A.
(Service de Physique Theorique Centre d 'Etudes Saclay, France)
KUBONO Shigeru ~1~dff(Inst. Nucl. Study, Univ. Tokyo)
KUSAKARI Hideshige 1/f XU ~:jft (Fac. Ed. , Chiba Univ.)
LEE Sang Mu*13(Inst. Phys., Univ. Tsukuba)
LIU Guanhua ;IJ(Inst. Mod . Phys. , Acad. Sin., China)
MAEDA Kazushige M B3 fD(ColI. Gen. Ed. , Tohoku Univ.)
MATSUYANAGI Kenichi ~ fP~ 1iJf (Fac. Sci. , Kyoto Univ.)
MIN Byung-Joo I¥J pg J)K (Korea Atomic Energy Res. Inst. , Korea)
MITARAI Shiro 1in~Ht;:t-1!B (Fac. Sci. , Kyushu Univ.)
MITSUOKA Shinichi -jt f8i] 1i - (Res. Center for Nucl. Phys., Osaka Univ.)
MIYACHI Takashi g j:tt! q: (Inst. Nucl. Study, Univ. Tokyo)
MIYATAKE Hiroari g it ~ -ill. (ColI. Gen. Ed. , Osaka Univ.)
MORIKAWA Tsuneyasu ~ }I[ -[:! [(Fac. Sci., Kyushu Univ.)
MORINOBU Shunpei ~ {§ i3t.IJl (Fac. Sci. , Kyushu Univ.)
MOTOBAYASHI Toru
if,* ~ (ColI. Sci., Rikkyo Univ.)
MOTTELSON Ben R.
(NORDITA, Copenhagen, Denmark)
MUELLER Ludwig(Univ. Padova, Italy)
MURAKAMI Takeshi t't L
1!£ (Natl. Inst. Radiol. Sci.)~(Fac. Sci. , Tokyo Inst. Technol.)NAGAI Yasuki 71-<
~ ~ -X(Inst. Phys., Univ. Tsukuba)
NAGASHIMA Yasuo
NAKAJIMA Mitsuo ~ ~ 1t X (Graduate School Nagatsuta, Tokyo Inst. Technol.)
NAKAMURA Shogo ~ f't iE ~ (Fac. Ed., Yokohama Nat. Univ.)
NAKAMURA Takashi ~ tf ~ P1 (Fac. Sci., Univ. Tokyo)
NAKAYAMA Shintaro ~ w{§*1!B (ColI. Gen. Ed., Tokushima Univ.)
NIIZEKI Takashi =$fT ~ ~ (Fac. Sci.,Tokyo Inst. Technol.)
NORO Tetsuo If g :Jgf -X (Res. Center Nucl. Phys. , Osaka Univ.)
ODAHARA Atsuko /j'\B3JJ?:J.J--1- (Fac. Sci., Kyushu Univ.)
OGAWA Masao /J'\}I[ ~ ~ (Graduate School Nagatsuta, Tokyo Inst. Technol.)
OKAMURA Hiroyuki [Tli] f't 5.L. Z (Univ. Tokyo)
ONUMA Hajime(Fac. Sci. , Tokyo Inst. Technol.)
ORIHARA Hikonojyo ~,*~zffs (Cyclotron and Radioisotope Center, Tohoku Univ.)~~~(JAERI)OSHIMA Masumi
OTSUKA Takaharu
q: ~a (Fac. Sci. , Univ. Tokyo)
OYAIZU Michihiro /j'\tg~~~1t~ (Inst. Nucl. Study, Univ. Tokyo)
RUAN (GEN) Jian-Zhi ~jG ~ ~a (ColI. ScL, Rikkyo Univ.)
SAGAWA Hiroyuki 1t. )I[ 1]1.. ~ (Center Mathematical Sci., Univ. Aizu)
SAKAGUCHI Harutaka :I:JX lJ ~a ~ (Fac. Sci., Kyoto Univ.)
SAKAI Kenji i!
1!£(Fac. Sci. , Tokyo Inst. Technol.)-jt -X(Inst. Nucl. Study, Univ. Tokyo)
SAKAI Mitsuo :I:JX
SAKURAGI Hiroyuki ~1]1.. Z
(Fac. Sci., Osaka City Univ.)
SATO Hikaru 1t. Hi Ili1f (Natl. Lab. High Energy Phys.)
SATO Hiroshi it. Hi tJi (Seikei Univ.)
SCHMIDT-OTT Wolf-Dieter(II Physicalisches Inst., Univ. Goettingen, Germany)
SHIBATA Toshiaki ~ B3 lrJ I=IJJ (Fac. Sci., Tokyo Inst. Technol.)
SHIMIZU Hajime til 7jc ~ (Fac. Ed., Yamagata Univ.)
SHIMIZU Yoshifumi m7jc ~)( (Fac. Sci., Kyushu Univ.)
SHIMODA Tad as hi r B3 iE (ColI. Gen. Ed., Osaka Univ.)*:t)ft

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SHIMOURA Susumu r ~i ~ (CoH. Sci., Rikkyo Univ.)
SHIRATO Syoji B ± w}
(CoH. ScL , Rikkyo Univ.)
SIGNORINI Cosimo(Phys. Dept., Inst. Nazionale di Fisica Nucl., Italy)
SUGAWARA Masahiko 1f ffit ~"ffi (Chiba Inst. Technol.)SUZUKI Masayo #~ itt(Jpn. Synchrotron Rad. Res. Inst.)
1L Z (Fac. Sci., Niigata Univ.)
SUZUKI Yasuyuki #TAKADA Eiichi rm ill(Natl. Inst. Radiol. Sci.)
TAKAHASHI Noriaki rm ~ 1! IlYJ (ColI. Gen. Ed., Osaka Univ.)(Fac. Sci. , Univ. Tokyo)
TAKAHASHI Tadayuki rm ~ }~, ¥TAKAKU Seisaku rm?-. iff f'P (Inst. Nucl. Study, Univ. Tokyo)
TAKIGAWA Noboru ~ )/[ ~ (Fac. Sci., Tohoku Univ.)
TANAKA Masahiko B3 9=' ?1t"ffi (Inst. Nucl. Study, Univ. Tokyo)
TANOKURA Atsushi illlff~ ¥X (Fac. Sci. Technol. , Sophia Univ.)
TERAKAWA Atsuki ~)I[" fit (Cyclotron and Radioisotope Center, Tohoku Univ.)
TOKI Hiroshi ± Il!i W (Res. Center Nucl. Phys. , Osaka Univ.)
TOYAMA Takeshi 7f. W ~l (N atl. Lab. High Energy Phys.)TOYOKAWA Hidenori ~)I[ ~ IDI\ (Res. Center Nucl. Phys. , Osaka Univ.)
UENO Hideki J::. lff ~ fit (Fac. Sci., Osaka Univ.)
UNO Masahiro ~ lff if.
(Ministry Ed., Sci. Culture)
WU Heyu ~ W ~ (Inst. Mod. Phys. , Acad. Sin., China)
YAMAMOTO Sukeyasu LiJ*ti ttR (Fac. Sci. Technol., Sophia Univ.)
YAMANISHI Teruya W g§ 7Y! -ill. (Res. Center Nucl. Phys., Osaka Univ.)
YAMAYA Takashi W ~ ~ (Fac. Sci. , Tohoku Univ.)
YOSHINAGA Naotaka
7]( ~ q: (CoH. Liberal Arts, Saitama Univ.)YOSOI Masaru ~~1t fit (Fac. ScL , Kyoto Univ.)

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(Students)
AOI Nori W 1t ~ (Fac. Sci. , Univ. Tokyo)ta (ColI. Sci., Rikkyo Univ.)
AOKI Kohji
CHAE Soo Joh ~ i* *1: (Dept. Phys., Seoul Natl. Univ. , Korea)
EBIHARA Minoru ~~~ffit ~ (Fac. Sci., Univ . Tokyo)
FUJITA Satoshi Iii ill rg: ~ (Fac. Sci., Univ. Tokyo)
FUJIWARA Hideki Iii Jm ~ fit (CoH. Sci., Rikkyo Univ.)
HARA Yosuke Jm ~$ 1r (Fac. Sci., Tokyo Inst. Technol.)
HARADA Masaki Jm B3 ~ fit (Fac. Sci., Tokyo Inst. Technol.)
HIRAI Masaaki .IJZ 1t iE IlJJ (Fac. Sci., Univ. Tokyo)
HISANAGA Isamu ?-. 71< ~ (CoH. Sci., Rikkyo Univ.)
HORI Junichi t}ffi JIIR (CoH. Sci., Rikkyo Univ.)
HORI Masaki t}ffi iE fit (Fac. Sci., Univ. Tokyo)
HORI Yoichi t}ffi ~~ (Fac. Sci., Tokyo Inst. Technol.)
HOSOMICHI Kazuo *1B:i1! W(Fac. Sci. , Univ. Tokyo)
IINO Hayato ~ lff ~ A (ColI. Sci., Rikkyo Univ.)
INOUE Masahiro 1t J::. ~(CoH. ScL, Rikkyo Univ.)
ISHIDA Satoru ~ ill tg (Fac. Sci., Univ. Tokyo)
ITO Kazuya W Iii fO -ill. (Cyclotron and Radioisotope Center, Tohoku Univ.)
ITO Mikihiko W Iii ~"ffi (Fac. Sci., Tokyo Inst. Technol.)
IWAMOTO Susumu :fi
f!t (CoIl. Sci., Rikkyo Univ.)(CoH. Sci., Rikkyo Univ.)
IWASA Naohito :fi ft[. it t
IWATA Yoshiyuki :fi ill ft Z (CoIl. Sci., Rikkyo Univ.)
IZUMI Hideaki lli 7]'( ~ IlYJ (Fac. Sci., Tokyo Inst. Technol.)
KANEDA Naoya 1t B3 it -ill. (Fac. Sci., Kyushu Univ.)
KATO Kenichi tm Iii'tl (Fac. Sci., Tokyo Inst. Technol.)
KATO Toshiyuki 1111 Iii {~¥ (Sci. Eng. Res. Lab. , Waseda Univ.)
KIDERA Masanori~ iE '!M;(Fac. Sci., Kyushu Univ.)
KIKUCHI Tadashi iJ jiB iE (CoH. Sci., Rikkyo Univ.)
KOBAYASHI Misaki /J'\ t* ~!IX (Sci. Eng. Res. Lab. , Waseda Univ.)
KOBINATA Hideo /J'\ B rOJ~::k: (Fac. Sci., Univ. Tokyo)
KOMIYAMA Tatsuto :i6 W JL A (Sci. Eng. Res. Lab., Waseda Univ.)

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298

KUBO Madoka ~ 1* p:] (Fac. Sci. Technol., Sophia Univ.)
KUROKAWA Meiko ~)II I3JJ -r (ColI. Sci., Rikkyo Univ.)
KUROKAWA Nobuo ~ filJ ~ fil (Fac. Sci., Tokyo lnst. Technol.)
MATSUZAKI Keiichi ~ ~ ~ (Fac. Sci., Univ. Tokyo)
MICHEL Xavier(Orsay Univ., France)
MINEGISHI Junichi IlJ$ J¥ *-41. (ColI. Sci., Rikkyo Univ.)
MINEMURA Toshiyuki~1 {~11(ColI. Sci., Rikkyo Univ.)
MIYACHI Takahiko g jill -ffi"ffi (lnst. Nucl. Study, Univ. Tokyo)
MIYAZAKI Kousuke g t1J~ 7'C 11'- (Fac. Sci., Kyushu Univ.)
MIZOI Yutaka ~ 1t: ~~ (lnst. Nucl. Study, Univ. Tokyo)
MOCHINAGA Kensuke ~ 71< ~ 1t- (Fac. Sci., Tokyo Inst. Technol.)
MORIYA Shingo ~ ~ • ~ (ColI. Sci., Rikkyo Univ.)
MURATA Tomoki ~1 EE ~ W (Fac. Sci. Technol., Sophia Univ.)
NAGATA Kazuhiko ft EE ~D"ffi (Fac. Sci., Tokyo lnst. Technol.)
NAGATA Kazuhiro 7k EE fD r.t (Fac. Sci., Univ. Tokyo)
NAITO Yutaka pq iii .ft (Fac. Sci., Univ. Tokyo)
NAKAMAE Shigefumi ~ M a x (Fac. Sci., Univ. Tokyo)
NAKAMURA Tadashi ~ ~1 if (Sci. Eng. Res. Lab., Waseda Univ.)
NAKANO Jo ~ lff ~ (lnst. Nucl. Study, Univ. Tokyo)
NARATO Masayuki ~ P ~ Z. (Fac. Sci., Tokyo lnst. Technol.)NISHIO Teiji [9 ~ tJt ~S (ColI. Sci., Rikkyo Univ.)
NONAKA Takamasa lff ~ fit if (Fac. Sci., Univ. Tokyo)
OGAMI Hiroshi ~ 1:. tf PJ (Fac. Sci., Tokyo Inst. Technol.)
OGAWA Hideto IJ\ JII 3'? A (ColI. Sci., Rikkyo Univ.)
OGAWA Hiroshi IJ\ )1/ tf,mP! (Fac. Sci., Tokyo Inst. Technol.)
OGURA Toshiyuki IJ\ ~ {~¥ (ColI. Sci., Rikkyo Univ.)
OKADA Hiroyuki ItnJ EE
Z. (Sci. Eng. Res. Lab., Waseda Univ.)
OONISHI Tetsuya[9 :g tij(;(Fac. Sci., Univ. Tokyo)
OTSU Hideaki "*~.f 3'? Bt (Fac. Sci., Univ. Tokyo)
OTSUKA Takanori±j( .. 1~(Fac. Sci., Univ. Tokyo)(ColI. Sci., Rikkyo Univ.)
OZAWA Ryozi IJ\ ¥ft 7C
SAITO Yoshitaka ~ iii 7¥ ~i: (Fac. Sci., Univ. Tokyo)
SAKAMOTO Naruhiko :iRnX:"ffi (Fac. Sci., Univ. Tokyo)
SASAKI Mitsuru 1ti:.~
1t (Fac. Sci., Osaka Univ.)
SATO Hiromi 1ti:. iii r.t j.fjj (Fac. Sci., Tokyo Inst. Technol.)
SATO Masaaki 1ti:. iii • m (ColI. Sci., Rikkyo Univ.)
SATO Masaru 1ti:. iii fI (Sci. Eng. Res. Lab., Waseda Univ.)
SATO Yoshiteru 1ti:. iii ~ Jr! (Fac. Sci., Univ. Tokyo)
SHIBATA Masataka ~ EE ~ ~ (Fac. Sci., Kyushu Univ.)
SHIMURA Masakatsu i0 ~1 if M1 (Fac. Sci. Technol., Sophia Univ.)
SHINODA Morihiko r~ EE ~"ffi (Sci. Eng. Res. Lab. , Waseda Univ.)
SHIRAKURA Tetsuya~ 1'iJt -tf1
(Fac. Sci., Osaka Univ.)
SHIZUMA Toshiyuki m. rl'f' {~11- (Fac. Sci., Kyushu U niv.)
SUZUKI Masataka ~ft
if ~ (ColI. Sci., Rikkyo Univ.)
TAJIMA Yasuhisa EE ~ ~ ~ (Fac. Sci., Tokyo Inst. Technol.)
TAKEUCHI Satoshi Jit pq .Jf;a (ColI. Sci., Rikkyo Univ.)
TANAKA Eiichi EE ~ ~ (ColI. Sci., Rikkyo Univ.)
TERANISHI Takashi ~ [9 rm (Fac. Sci., Univ. Tokyo)
TERASAWA Kazuhiro ~ ¥ft ~D~:F (Sci. Eng. Res. Lab., Waseda Univ.)
TERUNUMA Takashi ,~~~(ColI. Sci., Rikkyo Univ.)
TSUCHIDA Naohiko ± EE 1f"& (Fac. Sci., Univ. Tokyo)
TSUDA Masaki ~.f EB l.I W (Fac. Sci., Tokyo Inst. Technol.)TSUZUKI Yutaka :t~:m .ft (ColI. Sci., Rikkyo Univ.)
TUCHIDA Hideo ± EEl ~ ~ (Fac. Sci., Kyushu Univ.)
UCHIBORI Takeshi pq tJffi Jit PJ (ColI. Sci., Rikkyo Univ.)
WAKASA Tomotsugu :;ff ~ ~,mP! (Fac. Sci., Univ. Tokyo)
WATANABE Akira iJt jll I3JJ (Sci. Eng. Res. Lab., Waseda Univ.)
WATANABE Hiroshi iJt ~ Jt (Fac. Sci., Kyushu Univ.)

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299

WATANABE Yutaka ~ ill. fa. (Fac. Sci., Univ. Tokyo)
YAMAMOTO Yoshifumi tlJ
f1 ~ (Fac. Sci., Osaka Univ)(Fac. Sci., Tokyo Inst. Technol.)
YAMASHITA Toshiyuki tlJ T ~rJ ¥YANAGISAWA Yoshiyuki ~p iR. -N {T (ColI. Sci. , Rikkyo Univ.)
YONEDA Kenichiro *B3$-.M (Fac. Sci. , Univ. Tokyo)
YOSHIDA Takuji "5 B3 1'11 Ii] (ColI. Sci., Rikkyo Univ.)
YOSHIMI Akihiro "5 Jt ~ 1$ (Fac. Sci., Tokyo Inst. Technol.)**Atomic Physics Laboratory. ANDO Kozo
ni Ilijlj ~BENGTSSON Peter*2
KAMBARA Tadashi 1$ ffi{ JI *3
KOJIMA Takao M. /J\ ~ ~ X
NISHIDA Masami W3 B3 ~ ~SCHMIDT-BaCKING Horst*4
SOEJIMA Kouichi ~IJ ~ ~ YOSHIDA Takashi "5 B3 ~ i0

*1 Chief Scientist,*2 Visiting Researcher,

AWAYA Yohko ~ ~ '3§. r*l
IGARASHI Akinori 1i jitaJJ~1j
KAN AI Yasuyuki ~ =tr f* Z
NAKAI Yoichi ~ =tr ~~ OURA Masaki~m JI :fit
SHIMAMURA Isao ~ ~t ~ * 3
TANG Jian-Zhi ~ ~ i0
WATANABE Naoki ~J!i {fB ill[ W+"**3 Senior Scientist,*4 Eminent Scientist(Visitors)
AZUMA Toshiyuki Jf( {~{T (ColI. Arts Sci. , Univ. Tokyo)
DANJO Atsunori tIl:. ~ ~ (Dept. Phys. , Niigata Univ.)
DEPAOLA Brett D.
(Kansas State Univ. , U.S.A.)
DORNER Reinhard(Inst. Kernphysik, Univ. Frankfurt, Germany)
ENGSTROM Lars
(Univ. Lund, Sweden)
FUJIMA Kazumi ni Fj;l9 - ~ (Fac. Eng., Yamanashi Univ.)
FUKUDA Hiroshi
B3(Sch. Administration and Informatics, Univ. Shizuoka)
HARA Shunsuke ffi{ {~11'- (Dept. Gen. Educ., Tsukuba ColI. Technol.)
HARSTON Michael R.
(Dept. Math. , Univ. Nottingham, U.K.)
HINO Ken-ichi B ff f!l (Dept. Appl. Phys. Chern., Univ. Electro-Commun.)HIRAYAMA Takato .lJZ tlJ q: A (Dept. Phys. , Gakushuin Univ.)
HULDT Sven
(Univ. Lund, Sweden)
HUTTON Roger(Univ. Lund, Sweden)
ICHIMURA Atsushi~t
i!f.
(Inst. Space and Astronautical Science)
ISHII Keishi fJ =tr III Z(Dept. Eng. Sci. , Kyoto Univ.)
ISOZUMI Yasuhito 1i+;fl~A (Inst. Chern. Res., Kyoto Univ.)
ITO Shin W ni .. (Radioisot. Res. Cent. , Kyoto Univ.)
ITOH Akio W ni ;p}( ~ (Fac. Eng. , Kyoto Univ.)
ITOH Yoh W ni ~~ (Fac. Sci., Josai Univ.)
KAWATSURA Kiyoshi )1/ 00 t~ (Fac. Eng. Design, Kyoto Inst. Technol.)
KIMURA Masahiro~t JI,.
(Fac. Sci., Osaka Univ.)~t~(Argonne Natl. Lab. , U.S.A.)
KIMURA Mineo
KINK Ilmar(Univ. Lund , Sweden)
KOBAYASHI Nobuo /J\ if* 1§:K (Dept. Phys. , Tokyo Metrop. Univ.)
KOHARA Takao /J\ 1* q::K (Fac. Sci., Himeji lnst. Technol.)
KOIKE Fumihiro /J\ Hl!. )( tf (Sch. Med. , Kitasato Univ.)
KOIZUMI Tetsuo /J\ jj{ rg:K (Dept. Phys. , Rikkyo Univ.)
KOMAKI Ken-ichiro /J\4t1iJf- .M (Coll. Arts Sci., Univ. Tokyo)$.M (Natl. Res. Inst. Police Sci.)
KUROKI Kenro ~MARTINSON lndrek(Univ. Lund, Sweden)
MATSUO Takashi m ~(Dept. Pathol. , Tokyo Med. Dent. Univ.)
MATSUZAWA Michio m~":® ~ (Dept. Appl. Phys. Chern. , Univ. Electro-Commun.)
MERGEL Volker(Inst. fur Kernphysik, Germany)
MITAMURA Tohru ~EB~t W (Fac. Eng., Himeji lnst. Technol.)
MIZOGAWA Tatsumi iJ)l/ JlR E (Nagaoka ColI. Technol.)
MOKLER Paul
(GSI, Germany)

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300

MUKOYAMA Takeshi rOJ LlJ ~~ (Inst. Chern. Res., Kyoto Univ.)
NISHIDA Nobuhiko g§ EB {§" It (Fac. Sci., Tokyo Inst. Technol.)
NYSTROM Bosse(Univ. Lund, Sweden)
OHTANI Shunsuke~ 1~ 1r(Inst. Laser Sci., Univ. Electro-Commun.)
OKUNO Kazuhiko ~ If f[J 1ffi (Dept. Phys., Tokyo Metrop. Univ.)
SAKATA Hideaki :Iff EB ~ aJI (Fac. Sci., Tokyo Inst. Technol.)
SAKURAI Makoto ~* 1t ~ (Fac. Sci., Kobe Univ.)
SATO Hiroshi ftL Hi ~ ~ (Fac. Sci., Ochanomizu Univ.)
SATOH Kazuhiko ftL iii - 1ffi (Fac. Sci., Tokyo Inst. Technol.)
SATOH Yukinori ftc. Hi $" fFc (Res. Inst. Sci. Measurements, Tohoku Univ.)
SEKIOKA Tsuguhisa ~ 1m] ffiJP]!A. (Fac. Eng., Himeji Inst. Technol.)
SHIBATA Hiromi ~ EB~
(Res. Cent. Nucl. Sci., Univ. Tokyo)
tf (Tandem Accel. Cent., Univ. Tsukuba)
SHIMA Kunihiro ~SHIMAKURA Noriyuki ~:t" fFc Z(Fac. Sci., Niigata Univ.)~(Electrotechnical Laboratory)SUZUKI Isao ~ft
TAKAYANAGI Toshinobu rWJ:fP~ f~ ~ (Dept. Phys., Sophia Univ.)
TAWARA Hiroyuki ~ tf Z (Natl. Inst. Fusion Sci.)TERASAWA Mititaka ~ ~~ {Iii q: (Fac. Eng., Himeji Inst. Technol.)TOSHIMA Nobuyuki pi Ih.~ {§" $" (Inst. Appl. Phys., Tsukuba Univ.)
WAKIYA Kazuyoshi Hi ~ - ~ (Dept. Phys., Sophia Univ.)
WATANABE Shinichi al ill{§" (Dept. Appl. Phys. Chern., Univ. Electro-Commun.)
YAGISHITA Akira {g~ 1'" aJI (Natl. Lab. High Energy Physics)(ColI. Arts Sci., Univ. Tokyo)
YAMAZAKI Yasunori LlJ ~ ~YODA Jun
EB iM (National Research Laboratory of Metrology)
YOSHINO Masuhiro S If ~ rJ.L. (Lab. Phys., Shibaura Inst. Technol.)ZOU Yarning §B iII aJI (Jiao Tong Univ., China)

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(Students)
BITO Yasunori If:. Hi ~ ~IJ (Fac. Eng., Kyoto Univ.)
CHIBA Daisuke =f 3131
1r (Dept. Phys., Sophia Univ.)
FUJIWARA Masamichi Hi JJ lE ~iliU (Dept. Eng. Sci., Kyoto Univ.)
KAGAWA Makoto iff)ll A (Dept. Phys., Sophia Univ.)
KAGEYAMA Hiroyoshi J~ LlJ j;fi ~ (Fac. Eng. Design, Kyoto Inst. Technol.)
KANEKO Shinichi ~ --t- .. (Fac. Sci., Tokyo Inst. Technol.)
KIMURA Yasuyuki~1 $ Z(Dept. Eng. Sci., Kyoto Univ.)
NAKAI Yoshihiro q:t m IE tf (Fac. Eng. Design, Kyoto Inst. Technol.)NISHIDA Tetsuo g§ EB :gr /!J3 (Dept. Eng. Sci., Kyoto Univ.)fl~ ~(Dept. Phys., Rikkyo Univ.)
OKUMA Ryuji
SANO Mutsumi ftc. If H~ (Dept. Phys., Rikkyo Univ.)
SAWADA Hirokazu ¥~ EB ~~ fD (Fac. Sci., Tokyo Inst. Technol.)SUZUKI Hajime ~(Fac. Eng., Kyoto Univ.)(Fac. Eng. Design, Kyoto Inst. Technol.)
TAKAHASHI Ryohei rWJ m; ~ f
TAKEUCHI Hiroko tJ j1q ~~ --t- (Dept. Phys., Ochanomizu Univ.)
TAMAGAWA Yoshihisa ':&]11 f~!A. (Dept. Phys., Sophia Univ.)
TANABE Kunihiro EB ill~(Dept. Phys., Sophia Univ.)
TSUCHIDA Hidetsugu ± EB ~(Fac. Eng., Kyoto Univ.)
YAMAMOTO Reiko LlJ 5G Jfl' --t- (Dept. Phys., Sophia Univ.)

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Muon Science Laboratory

ISHIDA Katsuhiko 1:1 EB MJ 1ffi
KOYAMA Akio /J'\ LlJ ng ME
NAGAMINE Kanetada 71< ~ ~ I~\**
WATANABE Isao Vi ~ ~ it
* Senior Scientist,

KADONO Ryosuke r~ If ~ ~MATSUZAKI Teiichiro ~_*~m.e~.*
NAKAMURA Satoshi q:t;f:1 rg:
YAGI Eiichi )\
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** Chief Scientist

301

(Visitors)
AKIMITSU Jun f)( J't M! (ColI. Sci. Eng. , Aoyama Gakuin Univ.)Ji (U niv. Electro-Commun.)
ASAI Kichizo ~~BRIERE Tina Marie(Dept. Phys., State Univ. New York, Albany, U.S.A.)(Dept. Phys. , State Univ. New York, Albany, U.S.A.)DAS Prasad Tara~
(JAERI)HASHIMOTO Masashi
KATO Mineo 110 Hi !if ~ (JAERI)KINO Yasushi
IfJit; (Fac. Sci. , Tohoku Univ.)
KUROSAWA Kiyoyuki ~ if{
1T (JAERI)
MACRAE Roderick M.
(JSPS Fellowship)
I3JJ(Contract Researcher)
MATSUSHITA Akira
NISHIDA Nobuhiko g§ B3 f§"ffi (Fac. Sci., Tokyo Inst. Univ.)
NISHIYAMA Kusuo g§ LlJ ff ~ (Fac. Sci., Univ. Tokyo)
PONOMAREV Leonid(Kurachatov Inst. , Russia)
PRATT Francis Laurence(Dept. Phys., Univ. Oxford, U.K.)
SHIMOMURA Koichiro rl1~-.M (Fac. Sci., Univ. Tokyo)
STRASSER Patrick(Nucl. Phys. Div., Inst. Nucl. Study, Univ. Tokyo)
TANASE Masakazu ;OOJ if{ iE fO (JAERI)TORIKAI Eiko J~" ~ -I- (Fac. Eng., Yamanashi Univ.)
YONEDA Akira
B3 jlt (Messege Co., Ltd.)

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DAWSON Wayne(Fac. Sci. , Univ. Tokyo)

Magnetic Materials Laboratory
KATSUMATA Koichi Mj X *11: _*1
MATSUDA Masaaki ~ B3 m a~
*1 Chief Scientist,*2 Senior Scientist,

Plasma Physics Laboratory
OYAMA Hitoshi
LlJ ~

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OKADA Takuya IiYiJ EB ~ -tf! *2
TATARA Gen $ ~ ~ iJ!*3*3 Special Postdoctral Researcher

YANO Katsuki~ If Mj %Microwave Physics Laboratory
MINOH Arimichi ~ 8:tJ t£m

Semiconductor Laboratory(Visitors)
AONO Keiko 1f If .f1 -I-(ColI. Liberal Arts, Kitasato Univ.)

Inorganic Chemical Physics Laboratory
AMBE Shizuko tfi: $ ~ -IMATSUO Yukari ~~EiI~flj

MAEDA Kuniko
TAKAMI Michio

MB3f1)-IrWJ ~* Chief Scientist* •*(Visitors)
ARAI Nobuaki JiE
ISHII Keizo ;fi
KAWAI Jun fiiJ it-

302

f~ 1(:;(Dept. Fisheries, Kyoto Univ.)~(Cyclotron Radioisot. Cent. , Tohoku Univ.)
iJM1(Dept. Metallurgy, Kyoto Univ.)m~*Nuclear Chemistry Laboratory

AMBE Fumitoshi ti: tfB )( fi!{*
ITO H Yoshiko W JI( 7i -fKOBAYASHI Yoshio /J\ *~~OHKUBO Yoshitaka :*7,.f:*grWl

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ENOMOTO Shuichi fI~
IWAMOTO Masako ;;fiif. -fMAEDA Haruka ijiJ B3 Li Q 7)'>* Chief Scientist(Visitors)
AMANO Ryohei X ff ~.If (Fac. Med. , Kanazawa Univ.)
AS AI Kichizo ~~a Ji (U niv. Electro-Commun.)(Fac. Sci. , Osaka Univ.)
BABA Hiroshi .~ f~
ENDO Kazutoyo J! JIi. flJ ~ (Showa ColI. Pharm. Sci.)FURUKAWA Michiaki il)1I ~ IlJI (Fac. Sci., Nagoya Univ.)
FURUSATO Naohisa il It ~ 7,. (ColI. Sci. Eng. , Aoyamagakuin Univ.)
1ir (ColI. Sci. Eng. , Aoyamagakuin Univ.)
HARAKAWA Hiroaki
HIRUNUMA Rieko ffmflnI -f- (Showa ColI. Pharm. Sci.)
HULETT D. Lester(Oak Ridge Natl. Lab. , U.S.A.)
HSIA Yuanfu ~ 5t 1l (Dept. Phys., Nanjing Univ. , China)
ITO Nobuhiko W JIi. 1$ ft(Sch. Veter. Med. Animal Sci. , Kitasato Univ.)
ITO Yasuo W JIi. -* ~ (Res. Cent. Nucl. Sci. , Univ. Tokyo)
KANAZAWA Ikuzo ~ ~ ff ~ (Fac. Educ., Tokyo Gakugei Univ.)
KATAYAMA Masayuki Jt W !Jt Z (Fac. Agr. , Univ. Osaka Pref.)
KIMURA Kan *:f1 ~~ (CoH. Sci. Eng. , Aoyamagakuin Univ.)
KOJIMA Sadao /J\ §'b ffit ~ (Nucl. Med. Cent., Aichi Medical Univ.)
KOMURA Kazuhisa /J\:f1 fD 7,. (Fac. Sci. , Kanazawa Univ.)
KUNUGIYAMA Iwao lr, W Mt (Sch. Veter. Med. Animal Sci. , Kitasato Univ.)
LIU Bin ~IJ ;-~ (Dept. Tech. Phys., Peking Univ. , China)
MINAI Yoshitaka ~ ~ it ~ (Fac. Sci. , Univ. Tokyo)
MURAKAMI Hideoki :f1 1:: ~ J!. (Fac. Educ. , Tokyo Gakugei Univ.)
NAKAMURA Jin J:f:l:f1 t. (Univ. Electro-Commun.)
NASU Saburo ~B 3j =: llB (Fac. Eng. Sci. , Osaka Univ.)
OKAMOTO Yoichi [iYi]~-F (Showa ColI. Pharm. Sci.)
PENG Zhilin ~ 15 *~ (Wuhan Univ., China)
SAITO Tad as hi J%i JIi. ~ (Fac. Sci. , Osaka Univ.)
SHIBATA Sadao ~ B3 ~ -X (Natl. Inst. Radiol. Sci.)SHIBATA Seiichi ~ B3 ~ (Inst. Nucl. St udy, Univ. Tokyo)
SHINOHARA Atsushi r~
J!J (Fac. Sci. , Nagoya Univ.)
SHINONAGA Taeko 1i 71< ~j; -f- (Fac. Sci., Tokyo Metrop. Univ.)
TANAKA Akira B3 ~ ~ (Showa ColI. Pharm. Sci.)
WEGINWAR Rajiv G.
(Chandrapur ColI. Eng., India)
71< ~ A (Jikei Univ. Sch. Med.)YANAGA Makoto
YASUDA Hiroshi 1* B3 Hi ~ (Natl. Inst. Radiol. Sci.)-f- (ColI. Sci. Eng. , Aoyamagakuin Univ.)
YOKOTA Yuko ;jJ( B3YOKOYAMA Akihiko ;jJ( W IlJI ~ (Fac. Sci., Osaka Univ.)
YOSHIDA Yutaka a B3 ~ (Shizuoka Inst. Sci. Technol.)* *'*)11 rs-

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(Students)
DAIRAKU Tomohisa :* ~ ~IJ 7,. (Fac. Sci. , Nagoya Univ.)
ENDO Rieko J!JIi.lJ.:fi -f- (Fac. Sci., Tokyo Metropol. U niv.)
1fx -ill. (Fac. Sci. Eng., Tokyo Denki Univ.)HAGIWARA Tetsuya ~HANYU Takafumi 5]5] 1:: .. )( (Showa ColI. Pharm. Sci.)
IIJIMA Yoshihide iIi §'b EB(Fac. Sci., Toho Univ.)
IMAIZUMI Manabu 4- 7'R ~ (Fac. Sci. Eng., Tokyo Denki U niv. )INOUE Takakazu
1:: .. fD (Fac. Sci., Osaka Univ.)
INOUE Takashi
1:: rWl ~ (Fac. Sci. Eng. , Tokyo Denki Univ.)
ITOH Masahiro 1jJ" iIi ~(Shizuoka Inst. Sci. Tech.)
ITOH Naoya W JIi. ill ~t (CoH. Sci. Eng., Aoyamagakuin Univ.)

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303

ITOU Mayu #t iii 1f* EE (Sch. Veter. Med. Animal Sci., Kitasato Univ.)
IWATA Maki ;fi 83 J{ *c. (Fac. Sci., Toho Univ.)aaa(Sch. Veter. Med. Animal Sci., Kitasato Univ.)
IWATSUKI Akira ;fi Ji
KAKIZAKI Takahiro trP ~ q: w.,. (Fac. Sci., Sci. U niv. Tokyo)
KATAYAMA Osamu J:t W fl~ (Fac. Sci., Toho Univ.)
KAWASAKI Yuko )11 ~ *ti -T (Fac. Sci., Toho Univ.)
KAWASHIMA Yasuko )11 ~ 1ft -T (Sch. Hygien. Sci., Kitasato Univ.)
KASUGA Ryouichi
B ~ ~ (Fac. Sci., Osaka Univ.)
KIKUCHI Yasuhisa *i W!. ~ 7-.. (Fac. Sci. Eng., Tokyo Denki Univ.)KIRYU Shigetoshi ttnJ 1: ~ ~IJ (Fac. Sci., Nagoya Univ.).KOBAYASHI Kanako /J'\~*W*-T (Fac. Sci., Tokyo Metropol. Univ.)
KUWABARA Kazunori ~ ffit ~D l! (Shizuoka Inst. Sci. Technol.)
MASUDA Yasuhisa ~ 83 ~ 7-.. (Shizuoka Inst. Sci. Tech.)
MINAMI Hiroshi rfJ ~ (Showa Coll. Pharm. Sci.)MIYABAYASHI Kyoko g *~ }j\ -T (Showa Coll. Pharm. Sci.)
MORIMOTO Shinya ~J{ IiX (Fac. Sci., Osaka Univ.)
MUKAI Kazuhiko rOJ ~D 1t (Fac. Sci., Osaka Univ.)
MURATA Chihiro t1 83 =f(Fac. Sci., Nagoya Univ.)
MUROYAMA Toshiharu ~ W f~ ~ (Fac. Sci., Nagoya Univ.)
NAKAGAWA Akihiro 9=J)l1 ~(Shizuoka Inst. Sci. Technol.)
NAKAJO Terunobu
i~ ~ i$(Tokyo Gakugei Univ.)ODA Hirotaka /J'\ 83 J[ it (Fac. Sci., Nagoya Univ.)
ODA Kaori /J'\ 83 W ~ (Showa Coll. Pharm. Sci.)
OIKAWA Shinji 11)11 J{ P] (Fac. Sci., Kanazawa Univ.)
ONIZUKA Nobuyuki J1b ±j( 1§ Z. (Tokyo Gakugei Univ.)~ 71< rnt
(Tokyo Gakugei Univ.)
OSHIMA Nagayasu
OTSU Yoko "*~.lt. -T (Tokyo Gakugei Univ.)
OZAKI Takuo If. ~ !it i!B (Fac. Sci., Tokyo Univ.)
SASAKI Jin ftrJ-<'* t(Tokyo Gakugei Univ.)
SATO Hisayuki ftL iii 7-.. 1-r (Shizuoka Inst. Sci. Technol.)
SAWADA Naoto 1" EEl lit A (Shizuoka Inst. Sci. Technol.)
SEKIGUCHI Akiko ~ IJ Ilj} -T (ColI. Sci. Eng., Aoyamagakuin Univ.)
SOG A Kyoko ~ fX
-T (Fac. Sci., Nagoya U niv.)
SOTOG AKU N aoki 7} jl:j Ll(Showa ColI. Pharm. Sci.)~ ~(Shizuoka Inst. Sci. Technol.)SUZUKI Akihiro jft
TAKAHASHI Yoshio jWj. ~ ~ ~ (Fac. Sci., Univ. Tokyo)
TANAKA Kenya 83
1iJf -t!! (Fac. Sci. Technol., Chuo Univ.)
TSUKAHARA Kazuhiro ±j( ffit ~ w.,. (Shizuoka Inst. Sci. Technol.)
UEDA Mikiko l::83~*c.-T (Dept. Botany, Stockholm Univ. , Sweden)~ ti(Shizuoka Inst. Sci. Tech.)
YAMAMOTO Chie W

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Chemical Dynamics Laboratory
KIMURA Kazuie
t1 ~ ~*(Visitor)
KAZAMA Shigeo

Ji. rl'l' 1i it

USHIDA Kiminori(Dept. Phys., Chuo Univ.)(Students)
HON Wan i~ jG (Dept. Chern., Tokyo Univ.)~(Dept. Phys., Chuo Univ.)
IIMURA Munefumi Ii t1
MORITA Toshio ~ EEl fit ~ (Dept. Phys., Chuo Univ.)
SEKIGUCHI Wataru ~ IJ fflt (Dept. Phys., Chuo Univ.)
YOSHIOKA Yoshiki 5 Itu] ~ tit (Dept. Phys., Chuo Univ.)*304:li EEl 1} m

Cellular Physiology Laboratory
HANAOKA Fumio 1t. Itu] X fil*
YATAGAI Fumio :£-illJ!X~*** Chief Scientist,

KITAYAMA Shigeru~t LIJ~~** Senior Scientist(Visitors)
ANDO Koichi 12 Jii J!. (N atl. Inst. Radiol. Sci.)
FUKUMURA Akifumi fi if'1 f1fJ ~ (Natl. Inst. Radiol. Sci.)
FURUSAWA Yoshiya tJ ~~ fl -tf1 (Natl. Inst. Radiol. Sci.)
HAM A Yoshimasa ~ ~ l§ (Sci. Eng. Res. Lab., Waseda Univ.)
HASHIMOTO Shozo ~~(Fac. Med., Keio Univ.)
HOSHINO Kazuo £!f - fit (Natl. Inst. Radiol. Sci.)IIZUKA Masayuki j j ±j( if. Z(Natl. Inst. Radiol. Sci.)
ITO Hisao W 7-. ~ (Fac. Med., Keio Univ.)
ITOH Hiroko W Jii ta- -f- (Natl. Inst. Radiol. Sci.)
ITSUKAICHI Hiromi 1i. B mV- 6;';' (Natl. Inst. Radiol. Sci.)
KANAI Tatsuaki ~Jt f1fJ (Natl. Inst. Radiol. Sci.)
KASAl Kiyomi 1l.
?If ~ (Natl. Inst. Radiol. Sci.)
KAWACHI Kiyomitsu filJ pq ?If JIt (Natl. Inst. Radiol. Sci.)
KIKUCHI Masahiro *J:till if. tf (JAERI, Takasaki)
KIMOTO Masafumi
5G if. ~ (Natl. Inst. Radiol. Sci.)
KOBAYASHI Yasuhiko /J'\ *~~(JAERI, Takasaki)
KOHNO Toshiyuki filJ!f {~Z (Natl. Inst. Radiol. Sci.)
KOIKE Sachiko /J'\ Hll. ¥ -f- (Natl. Inst. Radiol. Sci.)
KOJIMA Eiichi /J'\ ~(Natl. Inst. Radiol. Sci.)
KOSAKA Toshifumi /J'\:IR {~X (Dept. Vet. Radiol., Nihon Univ.)
KUBOTA Nobuo ~ ill R ~ (Fac. Med., Yokohama City Univ.)
MATSUFUJI Naruhiro ~ Jii nX: 51.. (Natl. Inst. Radiol. Sci.)
McINTYRE Cindy L.
(Radiobiol. Unit, Med. Res. Counc., U.K.)
MINOHARA Shinichi il 1* 1$ (Natl. Inst. Radiol. Sci.)(Natl. Inst. Radiol. Sci.)MIYAHARA Nobuyuki g 1* ffi ¥MURAISO Chidori if'1,liJ ~(Natl. Inst. Radiol. Sci.)
MURAKAMI Masahiro if'1 1: if."iJ.L. (Natl. Inst. Radiol. Sci.)
NAKAI Hirokazu r:p"iJ.L. fD (Dept. Agric., Shizuoka Univ.)
OHARA Hiroshi
1* "iJ.L. (Dept. Gen. Cult., Okayama Univ.)
OKUMURA Toshiyuki ~ if'1 fit Z (Fac. Med., Univ. Tsukuba)
SASAKI Hiroshi ftI:~* "iJ.L. (Fac. Med. Kyushu Univ.)
SHIKAZONO Naoya !t iii Ll BJG (JAERI, Takasaki)
SOGA Fuminori ~:JX X '§ (lnst. Nucl. Study, Univ. Tokyo)
SUDO Michio ~JUi~~fil (Natl. Inst. Radiol. Sci.)TAGUCHl Yasuko ill IJ-f- (Natl. Inst. Radiol. Sci.)
TAKATUJI Toshihiro iWi tt {~* (RI Cent., Nagasaki Univ.)
TANAKA Atsushi ill r:p~~(JAERI, Takasaki)
TANAKA Kaoru ill r:p 11 (Natl. Inst. Radiol. Sci.)~(Fac. Med., Univ. Tsukuba)
TATSUZAKI Hideo R ~TOMURA Hiromi j}. if'1 ~~ ~ (Natl. Inst. Radiol. Sci.)
TSUBOI Atsushi Pf
Ji!f (Natl. Inst. Radiol. Sci.)
TSUBOUCHI Susumu Pf pq :itt (Suzuka Med. Technol. Univ.)(JAERI, Takasaki)
WATANABE Hiroshi ill ill
WATANABE Masami ill ill if. C (Fac. Pharm., Nagasaki Univ.)
YAMASHITA Shoji L1J""f l§:Ix (Natl. Saitama Hospital)

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*

*

*

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(Students)
FUJI Hiroshi Jii
ta- (Fac. Med., Univ. Tsukuba)
KAWASHIMA Mitsuhiko fiiJ ~ JIt ~ (Fac. Med., Univ. Tsukuba)
TAKAHASHI Hideyuki iWi ·tMf
¥ (Fac. Med., Univ. Tsukuba)*

305

Plant Functions Laboratory
ABE Tomoko IlliJ {$ ~ -f-

YOSHIDA Shigeo

5 ill Z€ ~ ** Chief Scientist(Students)
KUMATA Shuji ~~ ill ~ ~STORASHIMA Takashi jf JI(~*(ColI. Agr. Vet. Med., Nihon Univ.)(ColI. Agr. Vet. Med. , Nihon Univ.)

Microbial Toxicology Laboratory
YAMAGUCHIIsamu W IJ~*
* Chief Scientist(Visitors)
WATANABE Tadakazu

ill {$ If;, ~(Agro-Kanesho Co. Ltd.)(Students)
MATSUMOTO Ken-ichi

m* 1@ ~

(Shimane Univ.)

Safety Center
HARASAWA Kaoru JJit iR ..
INOUE Yoshio 1t 1: ~ X.
KATOU Hiroko 110 JJi tf -fUWAMINO Yoshitomo 1:. Ji ~ 1m

IN AMURA Takashi T. fIB ~1 .!$i *KAGAYA Satoru 11oW~ 'I~
MIYAGAWA Makoto g)1I J{. g* HeadDivision of Surface Characterization
IWAKI Masaya ;fi
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KUMAG AI Makoto~~ ~YATAGAI Fumio~illJt)( x.** HeadRadioisotope Technology Division
N AKAN 0 Kazushiro ~ ff fD ;9£* Head(Visitors)
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ISHIKAWA Masanobu fi )1/ !ffE
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MAEZAWA Hiroshi FJ ~OGURA Koichi /J\ ~ f.tr. ~ (ColI. Ind. Technol. Nihon Univ.)
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SUZUKI Masao j~!ffE ~tt (Fac. Pharm., Nagasaki Univ.)
YATO Osamu
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MATSUMOTO Hideya306~ 9=' 1M! ~m*~ tiJ;(Fac. Sci. Eng., Waseda Univ.)(Fac. Sci. Eng. , Waseda Univ.)

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SAKATA Furnihiko:l:JXlBxffi::k~f*~~OHKUBO Yoshitaka::ki!§fg=tiJt::km ffi

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OHNUMA Hajirne
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SAKEMI Yasuhiro

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01 Makito

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SATOH Kazuhiko

11:ii-tt

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SATOU Yoshiteru

1ti.jJj.~55, 56, 57, 59, 179

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SAWADA Hirokazu

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SCHMIDT-BOCKING Horst W.

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SCHMIDT-OTT W.-D.
SCHWAB Wolfgang/J'\f~~x

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SEKIGUCHI Akiko

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169

61, 62, 63, 230, 232, 234,

OMATA Kazuo/J'\H.

60, 10955, 56, 57, 59, 179~1"fitz

OKUNO Kazuhiko50, 51, 67, 68, 72, 73,

SASAKI Hiroshi

SATO Kazunori

157

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OOKAWA Tornohiro

ff1ttifi

75, 76, 182, 186

OHTSUBO Takashi

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25

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203

123

238, 240, 244, 246

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SAKATA Hideaki

127, 128, 129, 158

OHTOMO Kiyotaka

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53

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TANIGAKI Minoru

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SHIMODA Tadashi

SHIN Seung-Ai

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TANABE Kosai

SHIKAZONO Naoya
SHIMAMURA Isao

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UMISEDO Sei

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UTSUNOMIYA Hiroaki

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VANDEGRIFF John

TAKAHASHI Ryohei

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WADA Michiharu

TAKAMI Michio

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WATANABE Masaki

WATANABE Tadakazu

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WATANABE Isao67, 182256
YOSHIDA Shigeo

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YOSHIDA Yukiyo

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54

YOSHIDA Yutaka

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aWiJ.E!m 163, 164~IIJ.~"¥

wEBfD7i

YAMADA Kazuyoshi

wEBJ}J~YAMADA Masami
YAMAGATA Tamio

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YAMAGAMI Munetaka

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YAMAGIWA Iwao
YAMAGUCHI Isamu

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YAMAJI Shuhei

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YAMAKAWA

Osamu

YOSHIOKA Yoshiki

122
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YOSOI Masaru~~1t

YUAN Youjin

238,240YUASA-NAKAGAWA Keiko186

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52,53,
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189
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RIKEN Accelerator Progress Report Vol. 29!11t~~~jiJT1.JDilnif.;'X~*~29J.f.

(1996)

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理化学研究所
埼玉県

和光市

広沢