ISSN 0289-842X

RIKEN
Accelerator
Progress Report
vol.

31

理化学研究所

The Institute of Physical and Chemical Research (RIKEN)RIKEN Accelerator Progress Report i1 (Q)(Q)71
January.December U'fI 'fI #"oL 31!~ it. ~ ffi ~ jiJi"

The Institute of Physical and Chemical Research (RIKEN)
Wako, Saifama, 3SI.Ol98 JAPANEditors

T. AbeA. GotoT. Ichihara

R. Kadono

T. Kambara

Y. Kobayashi

A. Ozawa

I. Shimamura

S. Yamaji

Y. Yamazaki

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.

PREFACEII.

OPERATION OF ACCELERATORSPage
1

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

.3

RRC and AVF Cyclotron Operations ................................................

5

The Tandem Operation

7

III.

RESEARCH ACTIVITIES

1.

Nuclear Physics

Momentum Distributions of the Core Fragment from the Nuclear Breakup Reaction
within the Glauber Model.. ...................... ...................... .............

9

Astrophysical S-Factors for 7Be(p,,)8B Determined by Coulomb Dissociation
Measurements ......................................................................

10

Shell Model Calculation of Magnetic Moments of Light Mirror Nuclei ................

11

Spin Dipole States of Deformed Nuclei ..............................................

12

A Giant Halo at the Neutron Drip Line .............................................

13

The Proton and Neutron Distributions in Na Isotopes: The Development of Haloand Shell Structure .................................................................

14

Structure of Unstable Nuclei Studied by Monte Carlo Shell Model ...................

15

Quantum Monte Carlo Diagonalization Method with Condensed-Pair Bases......... .

16

The Pseudo-Spin Symmetry in Realistic Nuclei ......................................

17

Double Giant Quadrupole Resonance...... ........................... ....... ........

18

Possible Enhancement of the El Decay Rates of Double Giant Dipole States....... ..

19

Possible Deviation of the Sum of Strengths for Double Giant Dipole Resonancefrom Harmonic Oscillator Limit.......................... .. ............... .. ... .....

20

Constrained GCM Calculations Based on 3D-CHFB .................................

21

Exotic State of 3D-CHFB ...........................................................

22

Signature and Angular Momentum in 3D-Cranked HFB States ......................

23

Doubly Periodic Motion in Superdeformed States ....................................

24

Triaxial Nuclei in Relativistic Mean Field Theory. . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . .

25

The Deformation Effect on the Pairing Gap .........................................

26

Thermal Damping Width of Giant Dipole Resonance in Hot Nuclei. .. ..... ... .......

27

Relation between the Damping of the Hot Giant Dipole Resonance andthe Complex Admittance of an Irreversible Process ..................................

28

Temperature Dependence of Quantal and Thermal Dampings of Hot Giant Dipole
Resonance ..........................................................................

29

Stability of the Thermal HFB Equation ......................................... ... .

30

Variation of Transport Coefficients for Average Fission Dynamics with Temperatureand Shape.. .............................. ................. ... ..... .. ... .. ........ ..

31

Collective Motion at Finite Excitations in Terms of Cassini Ovaloids .................

32

Nucleus as a Canonical Ensemble: The Inverse Laplace Transformation ..............

33

Damping Width of the Mie Plasmon ................................................

34

Explosion of a Neutron Star Just Below the Minimum Mass: A Possible Site forr-Process Nucleosynthesis ...........................................................

35

Relativistic Equation of State for Supernova .........................................

36

Can the Equation of State of Asymmetric Nuclear Matter Be Studied Using
Unstable Nuclei? ...................................................................

37

Exotic Nuclear Rod Formation Induced by Superfluid Vortices in NeutronStar Crusts .........................................................................

38

Dynamics of Exotic Nuclear Rod Formation for Neutron Star Glitches ...............

39

High Ratio of 44Ti/ 56 Ni in Cas A and Axisymmetric Collapse-Driven Supernova
Explosion ................' ..' ...................................' .......................

40

Low Energy Aspects of the Field Strength Approach ..... ................ . ...... .. .....

41

Nuclear Transparency in a Relativistic Harmonic Oscillator Quark Model

42

Quark Distributions in the Nucleon by the Semi-Inclusive Reaction on
the Proton- and 3He-Target .................................... . ....................

43

Parameterization of the Polarized Parton Distribution Functions .....................

44

Q2 Evolution of Polarized Parton Distributions ... , . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

45

NLO Q2-Evolution of the Nucleon's Transversity Distribution hl(X, Q2) ..............

46

The 'lj;' Production in Polarized pp Collisions as a Test of Color- Octet Mechanism ....

47

Heavy Quark Physics with Spin .....................................................

48

Measurement of a-Sticking Probability in Muon Catalyzed dt Fusion by X-ray
Method at RIKEN-RAL Muon Facility ..............................................

49

Fusion Neutron Yield and Muon Cycling Rate in Muon Catalyzed dt Fusion at
RIKEN-RAL Muon Facility.........................................................

50

K,e/K a Sticking X-ray Ratio in Muon Catalyzed dt Fusion at RIKEN-RAL Muon
Facility .............................................................................

51

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

52

Results from Beam Tests of PHENIX Muon Identifier ...............................

53

Spin Physics with Photon Detection at PHENIX ....................................

54

Studies of Systematic Problems in the Spin Dependent Structure Functions of
the Nucleon ........................................................................

55

High Spin Isomer Beam Experiment at RIKEN ......................................

56

Search for High-Spin Isomer in 143Nd ...............................................

57

2.

,-Ray Linear Polarization Measurement by Segmented Ge .......................... .

58

Measurements of Neutron Spallation Cross Sections of 59Co and natcu .............. .

59

Polarization Observables for the 3fie( J, p )4He Reaction ............................. .

60

Study of Spin Flip Signatures via 12C( d, d') Reaction ............................. . . .

61

Measurement of the 28Si(d, d!) Reaction at Ed = 270 MeV .......................... .

62

Gamow-Teller Strength Distribution in fp Shell Nuclei .............................. .

63

Low Background Measurement of 8B Coulomb Dissociation ......................... .

64

Measurement of Cross Sections of the 8Li (a ,n) 11 Band 8Li (a ,an fLi Reactions
with a New-MUSIC Detector ....................................................... .

65

Density Distribution of 9C Derived from Reaction Cross Sections ................... .

66

Inelastic Proton Scattering on 12Be in Inverse Kinematics .......................... .

67

Coulomb Excitation of 11 Be ........................................................ .

68

Coulomb Dissociation of 12N ....................................................... .

69

Quadrupole Moment of 13 0 ........................................................ .

70

Coulomb Dissociation of 17C and 19C .............................................. .

71

Measurements of the 18N Magnetic Moment and Electric Quadrupole Moment ...... .

72

Measurements of Half Lives and Neutron Emission Probabilities of the Neutron
Drip Line Nuclei 19B, 22C, and 23N ................................................. .

73

Lifetime Measurement of 31,3 2Ne

74

Coulomb Excitation of N",Z",2875

Production Cross Sections of Projectile-like Fragments in the 40 Ar + 18 1Ta Reaction
at 94A MeV........................................................................

76

Polarized 129Xe Solid for Polarizing Unstable Nuclei ........ . ........................

77

Coulomb Dissociation of 8B at 254 MeV /u ..........................................

78

Measurement of Interaction Cross Sections for Light Neutron Rich Nuclei

79

Atomic and Solid-State Physics
Electron Capture in Collisions of H+ Ions with S Atoms and Its Reverse Process
below ke V-Energies .................................................................

81

Theoretical Attempt for Double Ionization of Helium by Energetic
Charged-Particle Impact ............................................................

82

Superexcited States of the Hydrogen Molecule. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

83

Theoretical Study of Electron Scattering from CH2F2 Molecules .....................

84

Fluorination Effects in Electron Scatterings from CH4, CH3Fl, CH2F2, CH1F3,
and CF4 ........................"....................................................

85

The Coupling of Electron Thermalization and Electron Attachment in CCl4/ Ar
and CC1 4/Ne Mixtures .................................................. ~ . . . . . . . . . . .

86

Resonances in Ps- System ..........................................................

87Auger Transition Rates for Metastable States of the Antiprotonic Helium He+p

88

Fine and Quadrupole Structures of the Weakly Bound Systems [(dt/-L)ndee]
and [(ddp,)ndee] ................................................................. ...

89

State-Selective Differential Cross Sections of Electron Capturein 10 MeV Ar 8+-He Collisions .......................................................

90

Beam Foil Spectra of Highly Charged Neon Ions in Visible Region ...................

91

Beam Foil Spectra of Highly Charged Krypton Ions in Visible Region. ..... . .. .. .. ...

92

Lifetimes of Intercombination Lines in Highly Charged Nb ...........................

93

Inherent Problems with Beam-Foil Lifetime Measurements................... .. .... ..

94

Electron Spectra Arising from Collisions between 50 ke V N5+ and Ar ................

95

VUV Photon Emission Spectroscopy of Slow, Highly Charged Ions ...................

96

Defect Production and Electronic Excitation in Ion-Irradiated High-Tc
Superconductors ....................................................................

97

Effect of Heavy-Ion Irradiation on the Bi-Based Superconductors ..... ...............

98

Irradiation Effects of Swift Heavy-Ion on Polycrystalline La1.85Sro.15Cu04

99

Observation of Columnar Defects in Layered Materials Bombarded
by l36Xe+3l, l8 l Ta +37 , and 209Bi+ 37 by STM and TEM ...... ............. ... ........

100

Experimental Study of Single Event Burnout (SEB) Hardening on
POWER MOSFET ... ................. . .... ........ .............. ....... ...........

101

Change of Site Occupancy of Hydrogen in Nb on Alloying with Undersized Mo ......

102

Annealing of the CU3AU Irradiated with Protons, a-Particles and C Ionsat Liquid Nitrogen Temperature ............................... . . . . . . . . . . . . . . . . . . . . . .

103

Development of Experimental Setup for Laser Spectroscopic Study of Ionsin Superfiuid Helium. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

104

Muon Spin Relaxation in KCuC13 ...................................................

105

p,SR Studies on (Ndl-ySmy)o.5Sro.5Mn03 ...................... .... .................

106

Critical Spin Dynamics in Ndl-xSrxMn03 with x ~ 0.5 .............................

107/-L+SR Study of Heavy-Fermion Magnetism in Ce(Cul-xNixhGe2 ....................

108

p,SR Studies of Non-Fermi-Liquid Behaviour in Ce7Ni3 ..............................

109

Behavior of the Positive Muon in 2H-NbSe2 .........................................

110

p,SR Study on 2D Kagome Organic Magnet, m-MPYNNBF 4 ................... . .....

111/-LSR Study of Critical Behavior of p-CI-C 6 H4-CH=N- TEMPO .......................

112/-L+SR Study of Polaron Motion in Polyaniline .......................................

113

Muon Studies on the Weak Charge Transfer System
Anthracene/Tetracyanobenzene .....................................................

114

Electronic State of /-LAI Pseudo-Acceptor Centers in Si Probed by p,-SR .............

115

Development of an RF Resonance System for Pulsed Muon Beam Method
at RIKEN-RAL .....................................................................

116

3.

Radiochemistry and Nuclear Chemistry ·The Jump Mechanism of Self-Interstitials in Pure Iron

119

Dynamic Behavior of 57Fe Atoms in Solid Ar and Solid Xe ..........................

120

57Fe Mossbauer Studies Using 57Mn Nuclei Implanted into Al and Si ......... . .......

121

Coulomb Excitation in In-beam Mossbauer Spectroscopy ... .. .......................

122

Multitracer Study on the Permeation of Rare Earth Elements througha Supported Liquid Membrane ......... ................. .......... ................ . .

123

Model Study of Acid Rain Effect on Adsorption of Trace Elements on Soils (III) .....

124

Simultaneous Determination of Stability Constants of Humate Complexes
with Various Metal Ions Using Multitracer Technique. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

125Comparative Subcellular Distribution of Radioactive Mn, Fe, Zn, and Se Tracers in
Brain and Liver: Why, in Brain, Do most of Their Proteins Exist in Mitochondrialand Nuclear Fraction? ..............................................................

126

Comparative Distribution of the Trace Elements Sc, Mn, Fe, Co, Zn, Se, Rb, and Zr
in the Brain and Other Organs of C57BL/6N Mice ..................................

127

Metabolic and Biochemical Studies of Trace Elements in Hypercholesterolemic
Model Mice (I) .. .............................................. ........... ..... .....

128

Metabolic and Biochemical Studies of Trace Elements in Hypercholesterolemic
Model Mice (II) ............................ ... ......................................

129

Metabolic Study of Trace Elements in Se-Deficient Rats (II) .........................

130

Influence of pH on Release of Various Trace Elements from Transferrin ..............

131

Affinity of Bio-Trace Elements to Cell Component: In vitro Study Using
M ultitracer .........................................................................

132

Multitracer Study on Binding Activity of Various Trace Elements toMetallothionein .............................................. . ......................

133

Multitracer Study on Coordinating of the Rare-Earth Element with
Metallothionein ............................. ... .....................................

134

Transfers of Trace Elements from the Placenta to the Fetus of Pregnant Rat .........

135

Uptake and Translocation of Sr, Tc, and Cs in Soybean Plants ......................

136

Multitracer Study on Uptake of Elements by Turnip ....................... ..........

137

Metabolism of Trace Elements in Euglena gracilis Using the Multitracer Technique. . .

138

Possibility of the Existence of a Special Substance Involved in the Uptake of REE
by Dryoptreris erythrosora ..........................................................

139

Study on the Uptake Rate of Various Elements into Dryopteris erythrosora
by Multitracer Technique ...........................................................

140

Multitracer Study on Biosorption of Various Trace Elements in Yeast
Saccharomyces cerevisiae ..................... . .............................. . . . . . . . .

141

Heavy-Ion Induced Fission in the Medium Energy Region ......... . .................

142

Developement of High Intensity Polarized Slow Positron Beam Using 18F ............

143

4.

5.

6.

Radiation Chemistry and Radiation Biology

Screening of Plants for Soil-Radionuclide Accumulators

145

Possible Role of Soil-Microbes in Plant Uptake of Radionuclides .....................

146

Effects of Heavy Ions on Survival of Arabidopsis thaliana ............................

147

Effective Plant-lvlutation Method Using Heavy-Ion Beams (II) .......................

148

Cell Death and Mutation Induction on Cultured Cells by Irradiation of Heavy Ions
and X-rays .........................................................................

149

Cell Cycle Progression after Heavy-Ion Irradiation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

150

DNA Analysis of HPRT Mutations Induced by High-LET Carbon- and Neon-ion
Beams..............................................................................

151

A 100 ps Lived New Luminescence Component in Ion Irradiated Alumina.. ... ..... ..

152

Luminescence Spectra and Decay Curves of Ion Irradiated Diamonds

153

Instrumentation

Computing Environment Surrounding the Accelerator Research Facility ..............

155

Optimization of Hexapole Magnet for ECR Ion Source ............................ . . .

156

Development of the Slow Highly Charged Ion Beam below 100 eV j q from an ECRIon Source for Ion-Atom Collision Experiments ......................................

157

Precise Determination of Neutron Beam Polarization at 16 MeV ............. " .... ..

158

Developement and Characterization of the Self-TOF Neutron Detector ............. . .

159

Proton Induced Activation in GSO, BGO Scintillators ...............................

161

In-Vacuum Plastic-Scintillator Hodoscope for Low-Background Measurementsof Charged Particles ................................................................

162

Beta-Ray Imaging Detector Using Scintillating Fibers ...............................

163

Development of a Fast Two-Dimensional PPAC .....................................

164

A Large Area PPACjIonization Chamber ...........................................

165

A New Fluorescence Photon Detection System for Collinear Laser Spectroscopy

167

Final Calibration of Cosmic Ray Heavy Ion Telescope for First Brazilian
Scientific Satellite ...................................................................

168

Performance Study of Radiation Detectors for Spacecraft ............................

169

Fabrication of the Muon Magnet for the RHIC SPIN Project ........................

170

Plan of Computing Facility for RHIC Spin Project ..................................

171

Factory Plan for PHENIX Muon Identifier ..........................................

172

Design of Proton Polarimeter for AGS-E925

173

Material Analysis

RBS Study of Na Implanted Polystyrene

175

Chemical State Analysis of Third Period Elements in Atmospheric Air by
High-Resolution PIXE ..............................................................

176

IV.

Improvement in the Detection Limits of ERDA Using a Time-of-Flight Detection ....

177

Determination of the Mass and Depth Resolutions of TOF-ERDA

178

NUCLEAR DATA

Status Report of the Nuclear Data GroupV.

179

DEVELOPMENT OF ACCELERATOR FACILITIESProgress of RI Beam Factory Project......... ........................... ............

181

Improvement of Sextupole Magnet for RIKEN 10 GHz ECRIS .......................

182

Improvements of Low RF Power System in RIKEN 10 GHz ECRIS ..................

183

Electron Beams Indeed Lower the Ion-Trapping Potential Barrier via
Sheaths to Enhance the HCI Component in an ECRIS: Analytical Proof .............

185

RIKEN Duoplasmatron Ion Source: The Operating Principles Compared with ECRIS,
and the Direction for Future ........................................................

187

Warm-Electron Heating Mechanism in the Core of ECRIS Nucleus, and Relevant
Diagnostic System ..................................................................

189

Production of Multicharged Os Ion Beams from Organic Metal Compounds Using
RIKEN 18 GHz ECRIS .............................................................

191

Recent Development of the Variable-Frequency RFQ Linac for RILAC ...............

192

Phase Stabilization of Injection Beam to RIKEN Ring Cyclotron ....................

194

Beam Orbit Simulation in the Central Region of RIKEN AVF Cyclotron....... ......

196

Design of a Resonator for a Flat-Top Acceleration System in RIKEN AVF
Cyclotron. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . .

198

New Emittance Measurement Using Two PPACs ....................................

200

Heavy Ion Microbeam Project in RIKEN Accelerator Research Facility ..............

202

Initial Design of a Charge State Multiplier System for RIKEN RI Beam Factory .....

203

The Two Booster Ring Cyclotrons for RIKEN RI Beam Factory .....................

205

Orbit Analysis of RIKEN Superconducting Ring Cyclotron....... .. .................

206

Design of Sector Magnets for RIKEN Superconducting Ring Cyclotron.;. .. ..........

208

Design of a Prototype Sector Magnet for RIKEN Superconducting Ring
Cyclotron ....................................... . ...................................

210

Quench Stabilities of the Superconducting Wires for the Sector Magnetsof RIKEN Superconducting Ring Cyclotron .........................................

212

Analysis of the Injection and Extraction Trajectories in RIKEN Superconducting
Ring Cyclotron .....................................................................

214

Design Study of Injection System for RIKEN Superconducting Ring Cyclotron..... ..

216

Optimization of the Superconducting Dipole Coils for Injection System of
RIKEN Superconducting Ring Cyclotron. .. ... .. ... ..... .. ... ..... .... ............. .

218

Numerical Study of Single-Thrn Extraction for RIKEN Superconducting Ring
Cyclotron ...........................................................................

220

Design of the RF Resonators for RIKEN Superconducting Ring Cyclotron ...........

222

VI.

Estimation of Beam Chamber Pressure Required for RIKEN Supereonducting Ring
Cyclotron ...........................................................................

224

Design of Debuncher System in the Injection Line to Accumulator Cooler
Ring of MUSES ................................................ .....................

225

Study of Stochastic Cooling at Accumulator Cooler Ring of MUSES .................

227

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

229

Design of Slow Extraction System at Booster Synchrotron for MUSES ...............

231

Simulation Study of Ion Beam Bunching with Electron Cooler at Double
Storage Ring of MUSES ............................................................

233

Diffusion Beam-Beam Instability in the Presence of Beam Cooling. . . . . . . . . . . . . . . . . . .

235

Stationary Particle Distribution of Intense Bunched Beam in RF Accelerating
Field ...............................................................................

237

High Brightness Beam Transport in a Quadrupole Focusing Channel with
Octupole Field Component ..........................................................

239

Design of 300 MeV Electron Linac at MUSES .......................................

241

Design of Apple-II Type Undulator for MUSES.................. .. .. ..... ........ .. .

243

Safety Design of RIKEN RI Beam Factory ... .......................................

245

Spin Depolarization Due to Beam-Beam Instability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

246

Study of Spin and Orbital Motion in Siberian Snake Based on Calculated
Three Dimensional Magnetic Field ..................... . ... .... .....................

248

Calculation and Measurement of Magnetic Field in Half-Length Helical Snake
Magnet for RHIC ...................................................................

250

Optimization of Full-Length Helical Snake Magnet for RHIC

251

RADIATION MONITORING

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

253

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

254

Residual Induced-Radioactivity at the Old 160 em Cyclotron ........................

256

VII.

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

257

VIII.

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

262

IX.

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

264

X.

LIST OF SYMPOSIA

272

XI.

LIST OF SEMINARS

273

XII.

LIST OF PERSONNEL275

AUTHOR INDEX

I. PREFACE

This issue of RIKEN Accelerator Progress Reportreports research activities of the RIKEN Accelerator
Research Facility (RARF) during the calendar yearof 1997. The research programs have been coordinated in the framework of the project entitled Multidisciplinary Researches on Heavy Ion Science. The
project involves a variety of fields such as: nuclear
physics, atomic physics, nuclear chemistry, radiation
biology, condensed matter physics in terms of accelerator or radiation application, basic studies on energy
production, basic studies on accelerator cancer therapy, material characterization, application to space science , accelerator physics and engineering, laser technology, and computational technology. These activities involved 12 laboratories in RIKEN and more than
400 'researchers including outside users from domestic
and foreign institutions.
Major research activities of the RARF are based ona heavy-ion accelerator complex consisting of the K =540 Me V RIKEN Ring Cyclotron (RRC) and its subordinate accelerators, i.e., the energy-variable heavy-ion
linear accelerator (RILAC) and the K = 70 MeV azimuthally variable field cyclotron (AVF) , which havealtogether provided a beam time (on the target) of
more than 8000 hours through the year. Besides,
the RARF carries two international collaboration programs using oversea accelerator facilities: one is themuon science project at ISIS in collaboration with the
Rutherford-Appleton Laboratory (RAL), and anotheris the spin physics program at RHIC in collaboration
with the Brookhaven National Laboratory (BNL).
The three accelerators currently available deliver
heavy ion beams of a variety of elements with energies ranging from a few A MeV to 135A MeV. The
two injector machines (AVF and RILAC) are equippedwith ECR heavy ion sources. The AVF is additionally equipped with a polarized ion source for vector
and tensor polarized deutrons. Recently, the RILAC
has dramatically enhanced its capability by newly accommodating an 18 GHz ECR ion source accompanied with a frequency-variable RFQ pre-accelerator.
Heavy ion intensities have increased ten to hundred
times as compared to the original setup. The t hree accelerators injectors and RRC have been used in various
configurations. The RRC was mostly used for nuclear
physics study, while the RILAC and AVF were often
used for other fields in their stand-alone mode of operation. Nuclear physics and all the other disciplines
shared the total allocated beam time almost evenly.
The RARF is characterized by its emphasis on thescientific application of radioactive beams. Uniquely,
three different types of radioactive beams, i.e., 1)

projectile-fragment (PF) radioactive beam, 2) spinpolarized radioactive beam, and 3) high-spin isomerbeam, have been cultivated to facilitate a broad scopeof nuclear research. The PF beams are most widelyused by virtue of their versatility and prominent intensities. The spin polarized beams are particularly usefulfor radioactive NMR experiments. The isomer beam
intensity has been significantly improved, approaching a realistic level for application. These beams areprimarily used for the study of nuclear physics. Major subjects pursued are: 1) exotic nuclear structureand new dynamics of extremely neutron-rich nuclei(such as those with a neutron halo or skin), 2) nuclear astrophysics involving unstable-nucleus reactions,3) synthesis of new unstable isotopes far from the valley of stability, 4) extensive measurement of nuclear
moments, and 5) high spin physics by means of isomerbeams. Characteristic features of intermediate-energy
direct reactions are often exploited for such studies.
Symbolizing the achievements of this year, extremely
neutron-rich nuclei, 7H and 31 F, were newly synthesized. The radioactive beams were useful for other domains of science as well. In particular, application tocondensed matter science has been started to a large
extent by exploiting on-line capability of Mossbauer
and PAC spectroscopies which are feasible only with
RI beams.
Intermediate-energy heavy ions from the RRC havefound their own applicabilities. A strikingly efficientmutagenic effect has been observed when the embryoof a Tobacco plant is shot by heavy ions. Highenergy heavy ions were irradiated to the plants naturally placed in the air for desirable strength of LET
through sample. This has led to establishment of a
new scheme of mutant production which is efficient andwell-controlled. The method is so efficient that it is expected to offer new possibilities of bio-science researchthrough comparison between normal and mutagenic
samples. Several proposals along this direction are currently being prepared. Another remarkable development has been seen in the application field of radioactive tracer technique. High-energy heavy ion reactions
facilitate production of a wide variety of isotopes at
a time. This feature is exploited to cultivate a novel
multi-tracer methodology in which a radioactive tracer
source containing a variety of elements is prepared to
be injected into a sample. This enables to study circulation behaviors of different elements for a common
sample under a same condition, drastically improving
reliability and efficiency over the single-tracer experiments. Application of the method is rapidly extending
to the fields of bio-inorganic chemistry, dietetics, toxi1

cology, pharmacology, environmental issues, and medical fields in general.
Primary beams from RILAC were often used forstudies of atomic physics. In this context an extensive
program of beam-foil spectroscopy for highly-charged
heavy ions continues in collaboration with a group of
Lund University. More generally, atomic physicists appreciate a rich capability of the entire RARF accelerator complex in producing very highly charged ions. For
instance, a high precision recoil-ion momentum spectroscopy has been developed at RRC to open up a new
possibility of the impact parameter dependence analysis of high-energy atomic/ionic reactions.
As for the international collaboration projects, thepulsed muon beam facility at ISIS has entered into a
stage of steady operation. Success in application of
I-tSR method on biological investigation was one of theresearch highlights. Meanwhile, the spin physics program to investigate quark-gluon spin structure func-

tions of nucleons is in progress to be ready for thecommissioning of RHIC operation in 1999.
Beyond these activities of on-going programs the
RARF has been undertaking continuous efforts further
to strengthen scientific opportunities for future. In thisregard, the year of 1997 has marked a big mile stone:
A new project so-called RIKEN Radioactive Ion Beam
(RIB) Factory has been approved by the Government
to promote the next generation RIB science. To start
with, the first construction phase for the factory wasstarted this year, which involves a set of cyclotrons toachieve K = 2500 MeV acceleration capability. The
RARF has also committed to strengthen the international collaboration program. In this context, a new
RIKEN branch called RIKEN BNL Research Centerhas been installed to promote the RHIC physics program effectively. With these new projects approved welook forward to significant enhancement of the RARF
scientific activities in coming years.

M. Ishihara
Director
RIKEN Accelerator Research Facility

2

II.

OPERATION OF ACCELERATORSRIKEN Accel. Prog. Rep. 31 (1998)

RILAC Operation
E. Ikezawa, M. Hemmi, T. Chiba, S. Kohara, T. Aihara,* T. Ohki,*
H. Hasebe,* H. Yamauchi,* and Y. Miyazawa
A new pre-injector system (consisting of a variablefrequency folded-coaxial RFQ linac and a 18-GHz ECRion source) for RILAC was installed on the beam transport line coming from the existing 450 kV CockcroftWalton injector with a 8-GHz ECR ion source (NEOMAFIOS) in the end of 1996. The beam acceleration tests with the new pre-injector system have been
performed successfully. The detailed results of thebeam acceleration tests are reported in this issue. 1)
The beam acceleration tests with the existing injector
system were also carried out. The beam transmission
efficiency of the beam transport line using the existing
injector was increased from 30 to 50% by matching thefirst gap voltage of the acceleration column with thebeam extraction voltage of the NEOMAFIOS.
The RILAC beam service for users by using the new
pre-injector and existing one was reopened in January
1997. In this reporting period, RILAC has been in a
steady operation and has supplied various kinds of ion
beams for the experiments. Table 1 gives the statistics of the operation from January through December
1997. Table 2 summarizes the number of days allotted to individual research groups. The percentage ofthe beam time used by RIKEN Ring Cyclotron (RRC)
was about 51% of the total. The ions of 4He, llB, 12C,
16 0, 36 Ar, 40 Ar, 56Fe, 58Ni, 84Kr, 128Te, 129Xe, 136Xe,
18 1Ta, 208Pb, and 209Bi accelerated by RILAC were
injected to RRC. Tables 3 and 4 give statistics of the
RILAC ion beams injected from the existing injector
with the NEOMAFIOS and from the new pre-injector
with the 18-GHz ECR ion source, respectively. The.ion beams of 17 kinds of element were used for theexperiments and for beam acceleration tests. The percentage of the beam time to have used metallic ionsamounted to about 27% of the total.
Table 1. Statistics of the RILAC operation from January
1 through December 31, 1997.
Days%

Beam time

182

49.9

Frequency change

12

3.3

Overhaul and improvement

49

13.4

Periodic inspection and repair

19

5.2

Machine trouble

0

0.0

103

28.2

365

100

Scheduled shut down
Total

Table 2. Beam time allocated for individual researchgroups.
Days%

Atomic physics

45

24.7

Nuclear physics

2

1.1

Material analysis and development

8

4.4

Radiation chemistry

18

9.9

Accelerator research

16

8.8

Beam transport to RRC

93

51.1

182

100

Total

Table 3. Statistics of the RILAC ion beams using the
Cockcroft-Walton inj ector.
Ion
He
B
C
N
0
Ne
Mg
Ar
Ar
Kr
Nb
Xe
Ta
Pb
Bi

Mass . Charge state
1,2
4
II
2,3
12
2,5
14
3
16
2,3
20
3
24
5
36
5
40
6,8
11,13
84
12
93
136
15
181
16
208
16
209
16
Total

Days
8
9
4
I

8
7
2
4
19
19
2
7
3
4
9
106

Table 4. Statistics of the RILAC ion beams using the new
pre-injector.
Ion
N
0
Ar
Ar
Fe
Ni
Kr
Te
Xe

Mass
14
16
36
40
56
58
84
128
129

Charge state
2,55
5
5,8,11 ,12
7
8,9
11,18
18
17

Days
2
2
2
23
5
7
3
8
4

Xe

136

15,18,19,
20,27
Total

20
76

Sumijyu Accelerator Service, Ltd.

3

Table 5. Ion beam currents (eJ.LA) of all ion species that we have obtained by the NEOMAFIOS
until now. The beam extraction voltage (Vext) was 10 kV for this case. The reverse whiteletter number represents the ions accelerated by RILAC.

32
40 l r84
129 ~e1~~e:r

11_ _ 5 0 _0
18
_

SF,.
24_1
:07 101
AI
17
IlillIiD
1.2
1
10.5
KI
13.5
16.6
1 3.8~
2.2 Hh-l±31-;. . I F t ;0;-;1..4.j-+--f!X~c----l
13 7 v
E~I . 1
0.3
136xclxm

106 7.2
11

74ie
89

:~ ;~

98 ~o
102 u
103 :h106 'd107 \g115 In120
130 re139 .a140 ~e141152 m
158 :d
159 b

,n

::

_iF. 4 X4. n.1
B.• 4. rod

1.4

'~

166
169 'm174 'b
175 Lu180 flf
181
184 W
187 Re193
195
197 \u208 'b209 Ii

ra

1.8 3
4.35.
5.43.12.

1~

11
1.1 I 3.
19 .
10.5 1
10.4 1c.
1.2 , .
10

1
1
10.4

6.361.62.61 .30.50.3
3 4 .5 1.67.5 . 5
.6
_
6
3
27
1.2 4.55
10 .7
19.3 . I ~.
14.1 . I e .l
11 .7
. I <.6
I
1
I 8.4
I2
24 22
. 14
15.7
. II
11 1
_
5
I.B
11.3 1
13 .B
7.9
1.1 1
1.3
1.2 13
12.3
14.718.0
19.1 7
:O .B
1.8
14.7

~3 ~.~Y ,O) .4 X 4.n~

~1.~72~.~~~0~.B~=~=t=t=t=t=t=~~~~~."./'~.;.~r~~=~IIiIm

Mo. 0. n~

I 0.3
10 .3

IiII

10.1
10.7

1.2 I 0.9 I 0.4
2 11 .2 10.6 10.2
10.2
10 .
15. 13.6
11.4 10.7
1
10.4
13.
2 1.0
10.2
14. 13.6 12.4

2

16510

12

3

4

I~;

12

10

' .7I B.0

2.5;.~ 1 4.9

7416.1 14.7 13.11 .81 .0!Ru.2 X2. rod
IRh. ¢ I. roo
IPd .• 2. roo;A ... <;!:l. " .1
:In,O,.4 X4.rudSn{ . 4 X4. roo
Te02. 4 X4,roo
La,O). 4 X4. rnd
ICe{ . 4 X4. rod
1. 4. T" cruciblc
ISm. <;!4.roo
IGd20). 4 X 4. roo
10.2 ITh.5 x5. ro<i~1--'11;;c...al--'~;;-:5+-;I~c-;.-:1.9-h~""'6j+I~~~"'""').6+-+I"'"'
0 . 2~1~~~:!:.yi61,.~~·~rOd---j4.:D~f-;;~75l--O-7.:.;.
. 7E
I 5~.74;.:.;.
. I +I=+-.
9-+-+---l!IE~r'<;!.24. ~roo----lle.39. 10 10 19.0
14.
51 .3 10 .60 .1
ITm.2 X2 .roo
5. 14.2
14.9
13 . , 1 1.3
0.4 10.2
IYb. H. roo
3 1
14 106.1(50~f_u.2 X2. roo
.5 3.
7.6
--I~4_. 3 ~3;;.+.~;;:+~
11 0~' . 5+=,.I!IH~f...f..
~I~
2. ~roo--l
8.5
18 1
19
14 12
--I~_~5~:7hc;+~21:..:...:.1+0~. 6~IT~a...f..
• .!.L
I..~rod--l0 .9 1 1.4 1. 12.4
4
1.5 10 .9 . I e
Iw."! I. roo
4.8 7 110.€ 1: 11 8.3
4.1 4.3
2.3 1.8 1[(
IRe. 0 1. roo
12.99.
118.5 16.5
5.414
3.5
1.7 . I e
1.1
11r.I X l.roo
0 10 .8 1.2
3
3.1
. 2.4
1.7
IPt . n . roo
13.7
I:
17 141~.lI~I-4 '2.6 1 108
1.3
104.Tacrucible
7.7
14 13 11~__~±1 '~rlifil"1311
0 .•II~PbO. ~4IX~( 4f. roo~
3 .3
18 .3 1 0 _
~_
_
~3 1.
roo

3315.2!
160115C
18 25

We experienced following machine troubles in thisreporting period: (1) The No.4 resonator had a small
vacuum leak on a cooling pipe cooling a shorting plate.
The leaky part was soldered. (2) The No.1 and No.6 rf
power amplifiers were splashed with water due to thecooling pipe having had a small hole. Consequently,
the teflon insulators for a grid stub of the No. 6 rf
power amplifier were scorched by the leak current on
its wet surface. (3) An obsolete filament power supply for the final vacuum tube (No.1) was replaced bya new one. (4) Three water pumps for the cooling
tower water circuit, the ordinary water circuit, andthe deionized-water circuit were overhauled because ofa deterioration of the mechanical seals. (5) A part ofthe chamber wall (2 mm thick stainless steel) of the4

Jc(.4X 4. r,,1

11

II.

.

switching magnet had a big vacuum leak caused by
the heat of the converged ion beam hit on it. In thiscase the beam power on the wall was about 500 Watts.
With the NEOMAFIOS the ions of P, Ru, Pr, Tb,
Tm, Yb, Lu, and Pt were newly produced by using
the rod insertion method during this year. Table 5summarizes the beam currents of all ion species that wehave obtained by using the NEOMAFIOS until now.
The beam extraction voltage has been raised from 10 to
13 kV. As the result, the beam intensity has increased
by about 30%.
References
1) O. Kamigaito et al.: RIKEN Accel. Prog. Rep. 31, 192(1998).

RIKEN Accel. Prog. Rep. 31 (1998)

RRC and AVF Cyclotron Operations
M. Kase, A. Goto, T. Kageyama, 1. Yokoyama, M. Nagase, S. Kohara, T. Nakagawa, N. Inabe, K. Ikegami,
O. Kamigaito, M. Kidera, J. Fujita, H. Isshiki,* H. Akagi,* R. Abe,* R. Ichikawa,*
N. Tsukiori,* K. Takahashi,* T. Maie,* T. Homma,* K. Kobayashi,*
A. Yoneda, M. Kobayashi, and Y. Yano
In the annual period from January to December
1997, many kinds of beams were accelerated with the
RIKEN Ring Cyclotron (RRC) similarly to previous
years. Figure 1 shows the distribution of these beams
on an energy-mass space using open circles for the ionsaccelerated in 1997. Among them, beams which weretried for the first time, or whose intensities were remarkably improved during this period, are listed inTable 1, together with their acceleration data.
In the summer of 1997, several improvements weremade on a preinjector of RILAC. An extraction voltage of 18 GHz ECR ion source has been increased bya factor of two, and the vane structure of FC-RFQ
has been changed accordingly. As the result, we haveachieved beam intensities higher than 1 pj.tA for the
40 Ar beam at 7.6 MeV jnucleon. Since the officially restricted upper limit of beam intensity is presently one
pj.tA for all kinds of beams, we could not use the full
beam for experiment. We offered to increase this restricted number by a factor of 10 for the low energy
beams, and received the permission from the Government at the end of the year. In the following year
on, it will become possible to make the experiment of

0.6

200
•

Ions acceleraledfrom 198710 1996

o Ions accelerated in 1997

'2 150

o
II)
U;::l

~

6 100
RILAC-RRC

0.3
0.2

10

o

H C Al AI Fe
j' ' , ' I 'i

Kr
I'

o

Xe
ii"',
100

Er Ta

i" "

Bi
i
200
I

Atomic Mass Number

Fig. 1. The performance of RRC. The beams which wereaccelerated during the year 1997 are shown by open
circles and those which have been accelerated since 1987
are shown by solid circles.

Table 1. List of typical beams accelerated in 1997.
Particle

EnergyFrequency

HarmonicIS

RRC(MeV/n)(MHz)

No. (RRC)

+8

+13

100

29.0

Ar

+5

+5

7.6

18.8

28 Si
40

40

Charge state

Injector

Beam Intensity(e nA)IOECR+AVF

46

II

18ECR+RFQ+RILAC>1000

New beam

Ar

+11

+17

95

28.0

IOECR+AVF

70

56 Fe

+7

+7

7.6

18.8

II

18ECR+RFQ+RlLAC

200

58 Ni

+8

+8

7.6

18.8

II

18ECR+RFQ+RlLAC

120

+18

+18

21

28.1

10

ISECR+RFQ+RlLAC

~

+20

+36

70

25.0

10ECR+AVF

1

+19

+19

8.5

19.9

II

ISECR+RFQ+RILAC

180

+19

+19

9.5

19.1

10

ISECR+RFQ+RlLAC

120

+16

+36

15

23.9

N·ECR+RILAC

O.S

New beam

+16

+37

12

21.4

N·ECR+RlLAC
0.5

New beam

84 Kr
84 Kr

136 Xe136

Xe

208 Pb209 Bi209 Bi

+16

+37

15

23.9

10ECR:

N·ECR+RlLAC

New beam

New beam

New beam

1 OGHz ECR Ion Source

18ECR :

1 8GHz ECR Ion Source

N-ECR :

Neomafios ECR Ion Source

Sumijyu Accelerator Service, Ltd.

5super-heavy element research more efficiently using
this upgraded beam of several pJ.lA, while using a rotary target which was newly developed.
In this reporting period, some very heavy ions wereaccelerated one after another. 209Bi, which is the heaviest ion for the case of RILAC-RRC operation, and
208Pb were accelerated up to 15 MeV/nucleon to be
used for nuclear physics experiments. On the other
hand, 84 Kr which is the heaviest ion acceleratable forthe case of AVF -RRC operation was successfully accelerated too up to 70 MeV/nucleon to be used forbiomedical experiments. As the result, the beam available regions in the energy-mass map have covered up
all the area as shown in Fig. 1.
For the production of metallic-ion beams, a new
method so-called MIVOC (Metal Ion from VOlatile
Compounds) 1) was tried with the 18 GHz ECR ion
source. Organic metal compounds, whose vapor pressure is high at room temperature, were used, instead of
conventional metallic or metal-oxide rod, for charging
metal vapor into an ECR plasma. Beams of Fe+ 7 andNi+ 8 were accelerated by RRC using the compounds ofFe(C5H5h and Ni(C5H5h, respectively. We obtained
a remarkable improvement on the intensity: ten times(e.g., for Ni) compared to conventional method.
Table 2 shows the statistics of the RRC operation
during January to December 1997. A total of operation hours of the year amounted to 6500 hr, and among
those, 4500 hr were spent for experiments. This value
is about several percent less than that of the previous
year. It is because most of nuclear physics experiments
have been concentrated on the use of RIPS. This forced
us to arrange all their experiments with considerable
time intervals between two experiments for preparation since the same room is used: loss of the total
experimental hours a year.
Table 2. Statistics of RRC Operation from Jan. to Dec.
1997.

rimento Other field Ex

rimentMachine Trouble
Guest Time
Maintenance & Holida s

Most of the beam time (75%) was devoted to the
nuclear physics experiments. The rest (25%) was devoted to the other fields such as: medical science,
radio-chemistry, health physics, material science, biology, and atomic physics.
A total of beam time for the stand-alone use of AVF

6

cyclotron amounted to 700 hr. The beam time is limited by a periodic maintenance (once per two months)
for a deflector of AVF cyclotron. Fo'u r kinds of lowenergy beams (polarized-d, alpha, C, and Ar) wereused for Moessbauer, nuclear physics, and for RI production.
A total of hours of unscheduled shutdown was reduced slightly compared to that in the previous years.
It is because a scheduled maintenance for deflector in
AVF cyclotron used up this period. The septum ofdeflector was cleaned once per two months.
In July, the machine was stopped for three days due
to a trouble of the electric deflector channel (EDC) of
RRC. At the end of 1997, one of the power supplies forinjection dipole magnets of RRC had a trouble aroundits sensing shunt. This shunt was of the facility's oldest
type: namely, a directly-water-cooled type. A part ofthe shunt material was electrically eroded because thesilicon rubber coating on it became aged. As the result,the current stability became worse. A change of theall old type shunts into a new type will be required in
the near future, as the shunts in most power supplies
were already converted into new ones of indirect-watercooled type several years ago.
A new vacuum leak has occurred in the resonator#2
of RRC, which caused from some part of the high pressure air line to actuate the contact finger of a movablebox. Fortunately, this leak has become small to a tolerable level during operation, though the reason for it
is not clear. Though its urgent repair is not required
badly at present, it should be done during the next
long-term maintenance period.
In order to increase the total efficiency throughRRC in the RILAC-RRC, two improvements have been
made as follows: (1) The structure of four-gap drift
tube in rebuncher, which is located half-way in the
beam transport line between RILAC and RRC, waschanged to be matched to the harmonic number ofRRC. The three sets of drift tube are now available forharmonic numbers, 9, 10, and 11. (2) Beam energy atthe exit of RILAC was stabilized by a feedback loop to
the rf of RILAC. 2) Since the fluctuation of beam energy
causes the beam phase fluctuation after drifting along
the beam transport line toward RRC, the rf phase canbe controlled in the final resonator of RILAC according
to the beam phase measured near the rebuncher. Thismethod was applied in the cases of 7.6 MeV/nucleon
40 Ar and 136Xe accelerations. As the result, we weresuccessful to improve the beam transmission efficiency
through RRC, as well as the beam stability.
References
1) T. Nakagawa et al.: Jpn. J. Appl. Phys. 36, 7375 (1997).
2) M. Kobayashi et al.: Proc. 11th Symp. on Accelerator
Science and Technology, Hyogo, Oct. 1997, p. 531.

RIKEN Accel. Prog. Rep. 31 (1998)

The Tandem Operation
K. Ogiwara, E. Vagi, and T. Urai
The tandem accelerator was operated for 90 days,
except for the machine inspection, beam test, and soon, during the annual reporting period from Nov. 1,
1996 to Oct. 31, 1997. A new beam line was constructed for the conventional Particle-Induced X-ray
Emission (PIXE) spectroscopy.
Experimental studies on the following subjects havebeen performed and are in progress.
(1) Rutherford Backscattering Spectroscopy (RBS)(a) Behavior of the Xe atoms implanted into iron(Muon Science Lab).
(b) RBS analysis of the polystyrene surfaces modified by ion implantation (Surface Characterization
Center).
(c) RBS study of multilayer films, welded steel, andoxides (Linear Accelerator Lab).
(2) Nuclear Reaction Analysis (NRA)(a) Lattice location identification of hydrogen in niobium alloys by a channeling method (Muon ScienceLab).
(3) Particle-Induced X-ray Emission (PIXE)(a) Application of PIXE to the 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).
(c) Development of an in-air high-resolution PIXE
system for chemical state analysis (Inorganic Chemical
Physics Lab).
(d) Channeling analysis of dopants in II-VI compound semiconductors (Muon Science Lab).
(e) Trace element analysis of feather (Safety Center).

7

III.

RESEARCH ACTIVITIES1. Nuclear Physics

RIKEN Accel. Prog. Rep. 31 (1998)

Momentum Distributions of the Core Fragment from the
Nuclear Breakup Reaction within the Glauber ModelY. Ogawa and 1. Tanihata[Longitudinal momentum distribution, Core absorption effect, Centrifugal force]
It has been considered that the core fragment momentum distribution arising from the breakup reaction
is a good probe to investigate the motion of the nucleon at the nuclear surface. This method, as well as
the measurement of the interaction cross section, is applied to study the structure of the neutron and protonrich drip-line nuclei. Since the reaction mechanism has
been usually ignored, there is a serious discrepancy between the interpretations of experimental result of thenuclear size and of the momentum distribution. In order to solve this problem we have demonstrated theinfluence of the core absorption effect on the width ofthe momentum distribution for different orbitals (s, p,
and d) of the last nucleon by calculating the longitudinal momentum distribution of core fragment within
the Glauber model. The (11 Be, lOBe), (8B, 7Be), and9 C, 18C) reactions on the light target are taken as
the typical examples for the s, p, and d orbitals of thelast nucleon. I)
We have obtained the following conclusions:(1) The core absorption effect is small for the sorbital case but is remarkably large for the p and dorbital cases. The probability with which the last nucleon is found in the core absorption area (see Fig. 1)
is larger for the p and d-orbital cases than the s-orbitalcase due to the centrifugal force. In this region, even if
the last nucleon hits the target, since the core nucleus
is simultaneously absorbed with a large probability,
such a channel dose not contribute to the cross section
which we detect. Since this large cross section reduction occurs in not so high momentum region either, thewidth of distribution becomes narrow for the non-zeroorbital case. I ,2)(2) We can consistently understand the narrow
width of 7Be core fragment momentum distribution
with the spatial extent like the normal p-shell nucleiof the 8B nucleus by taking into account the coree-

incident direction-@target{~---~~~:;Jcleus

prob'-i_il_ity_ _) _____,_
" _,,

o

RF + RT

impact parameter

Fig. 1. The core fragment breakup with a large probability
in the cylindrical region whose radius is the sum of thecore and target nuclear radii.

absorption effect. I)(3) Even if the large cross section reduction occurs
for the d-orbital case, the difference in the momentum widths between the sand d-orbital cases is verylarge. We can distinguish the dominant component oflast nucleon in the projectile according to the widthof measured fragment momentum distribution and thetotal cross section. Our calculation indicates that thes-state is a dominant component in the ground stateof 19C nucleus. 2)
References
1) Y. Ogawa and T. Tanihata: Nucl. Phys. A 616, 239c
(1997).
2) Y. Ogawa: Proc. 3rd Japan China Nuclear Physics
Symp., July 24-29, 1997, Sendai, Ogatu, Niigata,Japan.

9

RIKEN Accel. Prog. Rep. 31 (1998)

Astrophysical S-Factors for 7Be(p,,)8B Determined by
Coulomb Dissociation Measurements
T. Motobayashi, T. Kikuchi, N. Iwasa, Y. Ando, M. Kurokawa, S. Moriya, H. Murakami, T. Nishio,
J.-Z. Ruan, S. Shirato, S. Shimoura, T. Uchibori, Y. Yanagisawa, T. Kubo, H. Sakurai, T. Teranishi,
Y. Watanabe, M. Ishihara, M. Hirai, T. Nakamura, S. Kubono, M. Gai,*1 R. France III,*1
K. 1. Hahn, T. Delbar,*2 P. Lipnik,*2 and C. Michotte*2(208Pb(8B,7Be p)208Pb, Coulomb dissociation, Astrophysical 8-factors for 7Be(p,'Y)8B]
We report new data of the astrophysical 8 17 factors
for the 7Be(p" )8B reaction extracted from our second 8B dissociation experiment. 1) The radiative proton
capture by 7Be at low energies is the most uncertain
nuclear input to solar models, and has direct relation
to the high-energy neutrino flux relevant to the "solar
neutrino puzzle". The first experiment 2) measured the
8 17 factors at the center-of-mass energies ranging from
0.7 to 1.7 MeV. The results are consistent with thedirect capture cross sections measured by Vaughn et
a1. 3 ) and Filippone et a1. 4) The second experiment was
aimed at improving statistical accuracy of data as well
as at measuring precise angular distribution to extract
E2 mixtures in the E1-dominant Coulomb dissociation
yield. I)
Radioactive 8B beams at 51.9 MeV/nucleon were
provided by the RIPS separator, which bombarded a
50 mg/cm 2 208Pb target. Outgoing proton and 7Be
were detected in coincidence by a plastic-scintillator
hodoscope. The Coulomb dissociation yield was obtained as a function of the p-7Be relative energy andof the scattering angle ()8, angle of the p-7Be centerof-mass with respect to the beam direction. The resultant ()8 distributions were analyzed by a distorted
wave calculation. The result suggests very small e= 2
amplitudes, which supports the analysis with pure E1
transition in extracting 817 factors. Details of the experimental setup and of the analysis on the ()8 distributions were reported in Ref. l.
The 817 factors extracted from the second experiment are shown in Fig. 1 together with the resultsfrom the first experiment and those from the direct
7Be(p" )8B measurements. As seen in the figure, amuch better statistical accuracy is achieved in the second experiment. The Coulomb dissociation results
shown in the figure were obtained by assuming E1 tran-

*1

*2

10

Department of Physics, University of Connecticut, U.S.A.
Institut de Physique Nucleaire, Universite Catholique deLouvain, Belgium

140
7Be(p,y)8B

120
100

:0-

:>

80

ul

60

~

40

II

j t£f1II..
J\

'1111

,1\11lJ
• • +
I !

20

II I 1

Hf t •• ~

~fl.

.

0
0

500

1000

1500

2000

2500

3000

Ecm (keV)

Fig. 1. Astrophysical S17-factors extracted from thefirst (thick crosses) and second (large solid dots) experiments together with existing (p,,) data.

sit ion with small corrections due to the e = 2 component evaluated by the analysis of the ()8 distribution
discussed in Ref. 1. The two results are slightly different from each other, but both are consistent withthe (p,'Y) data by Vaughn et a1. 3 ) and Filippone etal.,4) who observed low values compared with the otherdirect-capture results.
References
1) T. Kikuchi et al.: Phys. Lett. B 391, 261 (1007); T.
Motobayashi et al.: RIKEN Accel. Prog. Rep. 30, 51(1997).
2) T. Motobayashi et al.: Phys. Rev. Lett. 13, 2680 (1994);
N. Iwasa et al.: J. Phys. Soc. Jpn. 65 , 1256 (1996).
3) F. J. Vaughn et al.: Phys. Rev. C 2 , 1657 (1970).
4) B. W. Filippone et al.: Phys. Rev. Lett. 50, 412 (1983);
Phys. Rev. C 28, 2222 (1983).

RIKEN Accel. Prog. Rep. 31 (1998)

Shell Model Calculation of Magnetic Momentsof Light Mirror Nuclei
H. Kitagawa, M. Tanigaki, T. Suzuki, and H. Sagawa[Shell model, Magnetic moment]
Magnetic moment (/-L), sum of spins (S) and angularmomenta (J) of nucleons, gives information on theiroccupation numbers in each orbit, which is a goodprobe for the nuclear physics. Recently, an anomaly
in the (A = 9, T = 3/2) mirror pair was reported l )providing that A is the mass number and T is the total isospin.
The experimentally observed value l ) of the isoscalarpart of this system is significantly larger than the value
calculated under the conventional shell model. The
effect of the first order configuration mixing is alreadyincluded in the shell model calculation. Fukunishi 2 )estimated the isoscalar part of the (A = 9, T = 3/2)
mirror pair, and has shown that it is impossible toreproduce the experimental value within the first orderconfiguration mixing. The effect of the second orderconfiguration mixing needs to be estimated. We havetherefore calculated both isoscalar and isovector parts
for the light nuclei whose mass numbers are from A = 8
to 13. Comparing with the experimental values, large
deviations are found in the isovector part of the (A = 8,
T = 1) pair, and in the isoscalar part of the (A = 9,
T = 3/2) pair.
We have then estimated the contributions of the second order configuration mixing to the isoscalar andisovector parts for the following five mirror pairs: (A =8, J7r = 2-, T = 1), (A = 9, J7r = 3/2 -, T = 3/2),(A = 11, J7r = 3/2-, T = 1/2), (A = 13, J7r = 1/2-,
T = 1/2), and (A = 13, J7r = 3/2-, T = 3/2). This
correction is divided into two parts: the one-body operator (core polarization Fig. 1) and the two-body operator (valence polarization Fig. 2). Two body matrix
elements are calculated from the one-boson exchange
potential,3) which includes the 7r-, p-, W-, and (j mesons
from the s-shell to the phf-shell. Particle exciations aretaken up to 4nw. Wave functions of the nucleon are
the harmonic oscillator type.
Results of calculations of the isoscalar part are
shown in Table 1. Corrections due to the second orderconfiguration mixing (core and valence polarizations),
together with the experimental and calculated values
by the shell model (within the first order configuration mixing), are listed. For the A = 9 mirror pair
it is desired to increase the isoscalar part of magnetic
moment, /-LIS, in order to reproduce the experimental
value. We can obviously see that the corrections ofthese polarizations are not enough. It may be difficult
to reproduce such a large deviation in the A = 9 pairwith the harmonic oscillator wave functions. As forCore Polarization

C-typeS-typeN-typeFig. 1. Typical diagrams of the second order configuration
mixing, core-polarizations.

Valence Polarization

Fig. 2. Typical diagrams of the second order configuration
mixing, valence-polarizations.
Table 1. Results of calculations of the isoscalar part ofmagnetic moment under the second order configuration
mixing.

(A, pr, T)(8,2+,1)(9, ~- , ~)(11, ~- , ~)(13, ~- , ~)(13, ~- , ~)core
-0.018- 0.010-0.006-0.009-0.0068/1/5
val.
-0.008-0.005-0.003+0.001- 0.004

J.LI5

expo cal.
cliff.
total- 0.026 1.344 1.332 +0.012-0.015 1.024 0.947 +0.077-0.009 0.862 0.871 -0.008-0.008 0.190 0.186 +0.004- 0.010 0.894 0.887 +0.008

the isovector part, effect of the meson exchange current will change it. We should also estimate the othercorrections of the Coulomb force and of the binding energy effect, by changing the wave functions of nucleon.
Our formulation is possible to include these effects.4)
References
1) K. Matsuta et al.: Hyperfine Interact. 97/98, 519(1996).
2) N. Fukunishi: RIKEN Accel. Prog. Rep. 29, 9 (1996).
3) 1. S. Towner: Phys. Rep. 155, 263 (1987).
4) H. Horie and K. Sasaki: Prog. Theor. Phys . 25, 475(1961).

11

RIKEN Accel. Prog. Rep. 31 (1998)

Spin Dipole States of Deformed Nuclei
H. Kurasawa* and T. Suzuki[Spin dipole states, Deformed nuclei]
The spin dipole states which are excited by (r xalkT have the total spin of either 0-, 1- or 2-. Since
they are a counterpart of the well-known giant dipole
states, it is a longstanding problem how they are distributed as a function of the excitation energy.
So far, the (e, e') and (p, n) reactions for 12C target showed the existence of the spin dipole states in
the giant dipole resonance region, and most of themwere considered to be 1- states. 1,2) Recently, however,Okamura et al. 3 ) have performed the (d, 2He) experiment, and found, through the tensor analyzing power,that the spin dipole resonance is mainly due to the 2states. We have thus studied theoretically the distribution of the spin dipole states in a deformed nuclear
model.
It is well-known that giant dipole states are split
into two groups in deformed nuclei. We take the oblate
shape nuclei, as an example. Then, the first group withlow excitation energy is composed of the K = 1 states,
while the second one with high excitation energy is dueto the K = 0 states . In the I'-absorption and (p,l'o)reaction, the ratio of the E1-strength of the first groupto that of the second one is 2 to 1, according to the
K -degrees of freedom. On the contrary, in the (p, 1'1)
reaction, the ratio is 1 to 2, according to the angularmomentum coupling. 1)
We can discuss the splitting of the spin dipole statesas to the matrix elements of (r x CT )fvrT3 in the sameway. The 0- spin dipole states are split into twogroups. The ratio of the strength of the first groupto that of the second group is 2 to 1. The 1- spin
dipole states are split into two groups, but in a different way from that of the dipole states. The 1- stateswith K = 0- are included in the first group, while
those with K = 1- are separated into the first and thesecond groups with the same strength. The 2- stateswith K = 1- are distributed in the same way as thatof the 1- spin dipole states with K = 1-. On theother hand, the 2- states with K = 2- appear only inthe first group. The 2- states with K = 0- are split
into the two groups with the strength ratio to be 1 to2.
We apply the deformed nuclear model to the giant dipole and spin dipole states of 12C. We have

Department of Physics, Faculty of Science, Chiba University

12

performed RPA calculations to describe the intrinsic
states of 12C using the Nilsson potential with the separable dipole-dipole and spin-dipole-spin-dipole interactions.
The results for the (I', n) cross section show that thetwo peaks at 22.5 and 25.5 MeV of the experimental
data are well reproduced by the K = 1- and 0- dipole
states, respectively. Comparison of our results withthe 11 B(p, rO)12C and 11 B(p, rd 12 C cross sections also
supports the present model very well.
Within the same framework, we have calculated
the strength of the spin dipole states. The collective
2- state is observable experimentally at 19.4 MeV.
The B(M2) value of this state is estimated to be
200 ± 50J.t~fm2 from electron scattering data,2) while
the present model yields 228J.t~fm2. Our calculations
show that the peak around 21 MeV is composed of the1- and 2- states, and about 2/3 of the strength is dueto the 2- states. We interpret this peak as the spin
dipole resonance like observed at 22 MeV in various
reactions.
In the present model, the collective 2- states with
K = 1- and K = 2- are found in the resonance region.
In particular the K = 1- state almost exhausts the
sum rule value. 1) In contrast to the 2- states, the 0and 1- states are not so collective, and the strength isdistributed over a wide energy region.
In conclusion, the distribution of the spin dipole
states of 12C, which is recently revealed by the tensor analyzing power of the (d, 2He) reaction, is qualitatively explainable in the deformed nuclear model.
The (I', n), (p, 1'0) and (p, I'd data are also reproducible
consistently. The distribution of the spin dipole statesin 12C, however, is fairly affected by the spin-orbit force
and the residual forces. It will be interesting to explore
how the spin dipole states are distributed in heavy nuclei.
References
1) T. Suzuki and C. Hinohara: Nucl. Phys. A 204, 289(1973).
2) C. Gaarde et al.: Nucl. Phys. A 422, 189 (1984).
3) H. Okamura et al.: Phys. Lett. B 345, 1 (1995).

RIKEN Accel. Prog. Rep. 31 (1998)

A Giant Halo at the Neutron Drip Line t
J. Meng and P. Ring*[Giant neutron halo, RHB theory]
With perpetual improvement in the techniques of
producing radioactive beams, the study of exotic nuclei very far away from the line of ,6-stability has now
become feasible. Experiments of this kind may cast
new light on nuclear structure, and novel and entirely
unexpected Features may appear: Neutron rich nuclei
can have a structure very different from normal nuclei.
They consist of a normal core surrounded by a skin ofneutron matter. Close to the drip line, where the coupling to the continuum becomes important, a neutron
halo can develop, as it has been observed in several
light nuclei, the most famous of which is 11 Li . However, in all of the halos observed so far, one halo has
only a very small number of neutrons, namely one or
two neutrons outside of the normal core. Even in the
chain of He-isotopes, only 6He shows indications of a
possible halo containing 2 neutrons , whereas 8He with
its large 2-neutron separation energy of 2.24 MeV has
only a skin of neutron.
In order to study the influence of correlations andmany-body effects it would be very interesting to findalso the nuclei with a larger number of neutrons distributed in the halo. In this letter we report on thetheoretical prediction of a giant neutron halo for Zrisotopes close to the neutron drip line. This halo isformed by up to six neutrons outside of the 122 Zr corewith the magic neutron number N = 82.
Recently, a fully self-consistent relativistic method
has been developed for the description of halo nuclei.
It is based on Relativistic Hartree-Bogoliubov (RHB)
theory in coordinate space.!) It is a relativistic extension of conventional Hartree-Fock-Bogoliubov theory
in coordinate space. 2) Being relativistic, it is able totake into account at the same time the proper isospin
dependence of the spin-orbit term which is very crucial
for the accurate reproduction of recent measurementsof the isotopic shifts in the Pb-region 3 ) and for the reliable description of nuclei far away from the line of,6-stability.4) In addition, this theory provides a selfconsistent treatment of pairing correlations in the presence of the continuum. As it has been shown in Ref. I
the scattering of Cooper pairs into the continuum containing low-lying resonances of small angular momentum plays an important role for the formation of aneutron halo. By using the density dependent zerorange interaction, the halo in 11 Li has been successfully reproduced in a self-consistent picture. Very good
Condensed from the article in Phys. Rev. Lett. 80, 460(1998)
Physik-Department der Technischen Universitat Munchen,
Germany

agreement with recent experimental data has beenobtained without any further adjustment of parameters. To obtain these results, a complete solution of
the RHB equations in coordinate space is necessary.
The expansion in a harmonic oscillator basis which isvery useful only for the nuclei close to the line of ,6stability, provides a very poor approximation in thecontinuum, even if a large number of oscillator shells
is taken into account. The simple Bardeen-CooperSchrieffer (BCS)- approximation used leads to a partial occupation of unbound states in the continuum andtherefore leads to a gas of evaporating neutrons. Here
we report on calculations (where the same method as
in Ref. I has been used) made to investigate halos inZr-nuclei at the neutron drip line.
We predict neutron halos in the Zr nuclei close to
the neutron drip line, which are composed not only by
one or two neutrons, as is the case in the halos investigated so far in light p-shell nuclei, but which containup to 6 neutrons. This is a new phenomenon, which
has not been observed experimentally. It would allow
the study of collective phenomena in neutron matterof low density. This prediction is based on RHB theory in the continuum. It combines the advantage of aproper description of the spin orbit term with that offull Hartree-Bogoliubov theory in the continuum whichallows in the canonical basis the scattering of Cooper
pairs into low-lying resonances in the continuum. A
density dependent force of zero range has been usedin the pairing channel. It contains no free-parameter,
because its strength is adjusted for the isotope 116Zr
to a similar calculation with Gogny's force DIS in thepairing channel. The halos are formed by two to six
neutrons scattered as Cooper-pairs mainly to the levels
3P3j2, 2f7/2' 3Plj2, and 2f5 / 2 · This is made possible by
the fact that these resonances in the continuum comedown very close to the Fermi level in these nuclei anddue to their coupling with the loosely-bound levels justbelow the continuum limit.
References
1) J. Meng and P. Ring: Phys. Rev. Lett. 11,3963 (1996).
2) J. Dobaczewski , H. Flocard, and J. Treiner: Nucl. Phys.
A 422, 103 (1984).
3) M. M. Sharma, G. A. Lalazissis, and P. Ring: Phys.
Lett. B 311, 9 (1993).
4) M. M. Sharma, G. A. Lalazissis, W. Hillebrandt, and P.
Ring: Phys. Rev. Lett. 12, 1431 (1994).

13

RI KEN Accel. Prog. Rep. 31 (1998)

The Proton and Neutron Distributions in Na Isotopes:
The Development of Halo and Shell Structure
J. Meng, I. Tanihata, and S. Yamaji[Halo, Shell structure, RHB theory]
The recent developments in the accelerator technology and in the detection techniques around the world
have changed the nuclear physics scenario. It is now
possible to produce and study the nuclei far away fromthe stability line-so called "EXOTIC NUCLEI". Experiments of this kind have cast a new light on nuclear
structure, and novel and entirely unexpected featuresappeared: e.g. the neutron halo in 11 Li 1) and neutron
skin along with a rapid increase in the measured interaction cross-sections in the neutron-rich light nuclei.
The extremely low proton to neutron ratio of these
nuclei and physics connected with these low density
matter have attracted increasing attentions in nuclear
physics as well as other fields such as astrophysics.
With an exotic matter distribution near the drip
line, a lot of questions are still open: e.g., the relation
between the halo and the shell effect, the difference
between the proton and neutron distributions on andaway from the stability line. How is the halo formed?
Are there a rapid change from the normal nuclear density to the halo density, or a gradual change in theparticle number? As the matter distribution is notmeasurable directly, series of experiments at different
incident beam energies are necessary in order to determine the model-independent density distribution ofboth proton and neutron. Among all the experiments
carried out so far, N a isotopes provide a good opportunity to study the density distributions over a wide
range of neutron numbers.2) We report here a systematic study of nuclear density distributions in Na isotopes within the Relativistic Mean Field (RMF) theory, with the pairing and blocking effects for odd particle system properly described by Hartree-Bogoliubov
theory in coordinate representation, and we try to answer some of the general questions in these low-density
nuclear matter.
Recently, a fully self-consistent calculation within
the Relativistic Hartree-Bogoliubov (RHB) theory incoordinate space for the description of the chainof lithium isotopes ranging from 6Li to 11 Li wasreported. 3) It combines the advantages of a proper
description of the spin-orbit term with those of fullHartree-Bogoliubov theory in the continuum, whichallows in the canonical basis the scattering of Cooper
pairs to low lying resonances in the continuum. Excellent agreement including binding energy, matter radius , and matter distribution with the experimental
data was obtained without any modification of the neutron Ip1 / 2 level like the former works. As the theory
used here is fully microscopic and parameter free, it
gives consistent description of the proton and neutron
distributions, and the development of proton and neu14

tron halos or skins could be examined.
Summarizing our investigations, the developmentof a proton skin as well as a neutron skin has beensystematically studied with a microscopic RHB theory, where the pairing and blocking effects have beentreated self-consistently. A systematic set of calculations for the ground state properties of nuclei in N a isotopes is presented using the RHB together with standard Glauber theories. The RHB equations are solved
self-consistently in the coordinate space, so that thecontinuum and pairing have been better treated. The
calculated binding energies are in good agreement withthe experimental values. A Glauber model calculation
has been carried out with the density obtained fromthe RHB. A good agreement has been obtained withthe measured cross sections for 12C as a target, and a
rapid increase of the cross sections has been predicted
for neutron rich Na isotopes beyond 32Na. The systematics of the proton and neutron distributions arepresented. After systematic examination of the neutron, proton, and matter distributions in the Na nuclei
from the proton drip-line to the neutron drip-line, theconnection between the tail part of the density and theshell structure has been found. The tail of the matter
distribution is not so sensitive to how many particles
are filled in the major shell. Instead, it is very sensitive
to whether this shell has an occupation or not. The
physics behind the skin and halo has been revealed as a
spatial demonstration of shell effect: simply the extra
neutrons are filled in the next shell and sub-shell. This
is in agreement with the mechanism observed so far in
the halo system but more general. As the 1£7/2 is very
close to the continuum, the N = 28 closed shell for stable nuclei fails to appear due to the coming down of the2P3/2 and 2P1/2 levels. Another important conclusion
here is that, contrary to the usual impression, the proton density distribution is less sensitive to the proton
to neutron ratio. Instead, it is almost unchanged fromthe proton drip-line to the neutron drip-line. Similar conclusion has been obtained recently by charge
exchange reaction experiment. 4 ) The influence of thedeformation, which is neglected in the present investigation, is also interesting to us, a further more extensive study to extend the present study in deformed
cases are in progress.
References
1) I. Tanihata et al.: Phys. Rev. Lett. 55, 2676 (1985).
2) T. Suzuki et al.: Phys. Rev. Let. 75, 3241 (1995).
3) J. Meng and P. Ring: Phys. Rev. Lett. 77, 3963 (1996).
4) O. Bochkarev et al.: submitted to Z. Phys.

RIKEN Accel. Prog. Rep. 31 (1998)

Structure of Unstable Nuclei Studied byMonte Carlo Shell Model
Y. Utsuno, T. Mizusaki, T. Otsuka, M. Honma, and N. Fukunishi[Monte Carlo method, Shell model, Shell closure]
Recent experimental studies on the neutron-rich nuclei have indicated that the shell gap at N = 20 vanishes in the 32Mg region. 1 ,2) Theoretically, the shellmodel approach to include lower part of the pf shellhave succeeded in describing the structure of N = 20
isotones. 3)
In order to obtain the eigen solutions of manybody quantum systems, the Quantum Monte Carlo
Diagonalization (QMCD) method has been proposed
recently.4) The QMCD method is applied to the largescale shell-model calculations, and is proved to be very
efficient. 5 )We apply the QMCD method to the large-scale shellmodel calculations for the N = 20 region. The same
valence shell and effective interaction as Ref. 3 are
adopted. We have developed a method to remove
the spurious center-of-mass motion suitable for the
QMCD method. Eigenvalues of the Hamiltonian for
yrast states obtained by three calculations are shownin Fig. 1. The energies obtained by the QMCD method
are much lower than those of any truncated model
spaces. Note that the basis dimensions of the M = 0
model space become about 1 million for the 4p4h
calculation. In the QMCD calculation, the expectation value of the center-of-mass Hamiltonian becomes
about 10- 4hw, which is a very small quantity. Thus,
8 .-----------------------~
6
4+-, o~­

::;-

<1>4

~

2+

X

LLJ

the feasibility of the QMCD method is confirmed.
Figure 2 shows the B (E2) values and pf-shellneutron-occupation probabilities for N = 20 isotones
by using the same Hamiltonian as Ref. 3. It turns outthat the neutron-rich N = 20 isotones are too muchdeformed for the Hamiltonian designed for the truncated model space. Therefore, we are looking for a
Hamiltonian appropriate for the larger model space,and about to start, for nuclei around 32Mg, the systematic calculations which were impossible with theconventional shell model.

600

(a)

j~ 400
~ 200

(If

Q;

o ~--+----~----+--~--~

~ 4
::J

Z

c::

~ 2
Q.

::J

80 L...-.----,-.J...-.----'-----::-::-'------'-------'
36

S

34

Si

3~g 30Ne

ot

Fig. 2. (a) B(E2;~ 2i) values, and (b) pf-shell neutron occupation numbers, for N = 20 isotones. The
dashed and dot-dashed lines in (a) correspond, respectively, to the B(E2) values by the 2p2h truncation andsd-shell calculation. The e p = 1.3e and en = 0.5e are
adopted as the effective charges.

,+

4 - O~---,'

2

References
2+ -

o

2+

"

0+ - 0+----------"Exp.

QMCD 4p4h

2p2hFig. 1. Energy levels of the lowest states of 32Mg. The
2p2h (4p4h) means the truncated model space, where
the number of neutrons excited to the pf shell is restricted to 2 (4). For t he 2p2h and 4p4h, the energies
relative to the ground-state energy of QMCD calculation are shown.

1) D. Guillemaud-Mueller et al.: Nucl. Phys. A 426, 37(1984).
2) T. Motobayashi et al.: Phys. Lett . B 346, 9 (1995).
3) N. Fukunishi, T. Otsuka, and T. Sebe: Phys. Lett. B
296 , 279 (1992).
4) M. Honma, T. Mizusaki, and T. Otsuka: Phys. Rev.
Lett. 75 , 1284 (1995) .
5) M. Honma, T. Mizusaki, and T. Otsuka: Phys. Rev.
Lett. 77, 3315 (1996) .

15

RIKEN Accel. Prog. Rep. 31 (1998)

Quantum Monte Carlo Diagonalization Methodwith Condensed-Pair Bases
N. Shimizu, T. Otsuka, T. Mizusaki, and M. Honma[Shell model, Quantum Monte Carlo method, Nuclear structure]
In order to study nuclear structure, the shell model
is one of the most useful approaches. In many shellmodel calculations, however, one has to diagonalize
Hamiltonian matrix in the full valence-nucleon Hilbert
space. The dimension of such a model space becomes
too large for heavier nuclei, prohibiting the diagonalization of the matrix. In order to overcome thisdifficulty, the Quantum Monte Carlo Diagonalization(QMCD) method was proposed by Honma et al. l - 3 )We outline first the framework of the QMCD here.
The QMCD is a method of solving many-body problems by diagonalizing the Hamiltonian in a subspaceconsisting of a tractable number (;S 50) of bases. Eachbasis is generated by utilizing an auxiliary field Monte
Carlo technique. The auxiliary field is controlled
stochastically, while the number of the bases needed
to express the eigenstates under investigation is suppressed by selecting more favorable bases.
This method mentioned above is successful in largescale shell model calculations. We can calculate wave
functions and restore various symmetries explicitly.
The basis has been a Slater determinant till now.
This seems to be very efficient for the nuclei lighter
than A rv 100. However, it turns out that we need
too many bases to handle larger systems with stronger
pairing correlations. Therefore, we propose to use
condensed-pair bases as the basis states instead ofSlater determinants.
The condensed-pair basis is written as 1 <p)(At)NI_), where N denotes one half of the number ofvalence nucleons, and 1-) is an inert core. The At is socalled lambda pair: At == Eij Aij c! c} with Aij being
the amplitude and c! the nucleon creation operator. 4 )One of the advantages to use this type of bases
is capability of using the solution of Hartree-FockBogoliubov method as an initial state.
We then compare the calculation with condensed-

16pair bases to the one with Slater determinant bases bytaking a simple system (Fig. 1). The Hamiltonian inthis system consists of a pairing interaction and single
particle energies. One can see that the condensed-pairbasis can express this system quite efficiently.

-93.0~ Slater det. basis

:>
Q)

~

I

o

Condensed pair basis

-93.5

v

o

0

o

0

o

-94.0

0

0

o

o

10

0

0

0

0

20

QMCD basis dimension

Fig. 1. Energies as a function of the QMCD basis dimension for the pfg-shell. H = G
pt P with G = -0.25
MeV. The Hartree-Fock-Bogoliubov solution is used as
the first basis in the condensed-pair basis calculation.

E

References
1) M. Honma, T. Mizusaki, and T. Otsuka: Phys. Rev.
Lett. 75, 1284 (1995).
2) M. Honma, T. Mizusaki, and T. Otsuka: Phys. Rev.
Lett. 77, 3315 (1996).
3) M. Mizusaki, M. Honma, and T. Otsuka: Phys. Rev. C
53, 2786 (1996).
4) T. Otsuka and N. Yoshinaga: Phys. Lett. B 168, 1(1986).

RIKEN Accel. Prog. Rep. 31 (1998)

The Pseudo-Spin Symmetry in Realistic Nuclei
J. Meng, K. Sugawara-Tanabe, S. Yamaji, P. Ring,* and A. Arima[Pseudo-spin symmetry, Relativistic mean field]
For thirty years the pseudo-spin symmetry 1,2) has
been used as a convenient concept, even though its
deep physical reason remains unknown. While the relativistic mean field has been proposed for more than
two decades and has been used as a relativistic versionof the conventional nuclear theory, it has proven to bevery successful.
Starting from the Dirac equation, Ginocchio found
an elegant way to connect between the pseudo-spinsymmetry and the equality in the scalar and vector
potentials. It was revealed that pseudo-orbital angularmomentum is the "orbital angular momentum" of thelower component of the Dirac wave function. 3 ) Fromthe point of Relativistic Mean Field (RMF), it is very
interesting to check how good the pseudo-spin symmetry is for the realistic nuclei. Here, starting fromthe standard RMF, instead of assuming the equality
in magnitude of the scalar and vector potentials, wehave treated the equation exactly and obtained a general formalism leading to the pseudo-spin symmetry.
It will be shown that there are two ways to solve theDirac equation. Concerning the energies of the solution for the large and small components, they appear
to be the same. The conventional way is to reduce theDirac equation to a Schrodinger type equation for theupper component, and the spin-orbital splitting is discussed. On the other hand, we can obtain an equation
for the lower component, and then the splitting will bein pseudo-spin. For example, we have chosen 88 Zr and
120Zr to study the energy splitting of the pseudo-spin
partners and its energy dependence in realistic cases.
The standard Dirac equation of RMF is as follows:[ei· p+ Vv(T) + (3(M + Vs (T))l1j!(f') = f.1j!(f') ,(1)

which describes a Dirac spinor moving in a potential
denoted by the scalar potential Vs (f) and vector potential Vv (T). In the following we will introduce the potential V = Vv(f) + Vs(f), which is around -50 MeV,
and the effective mass M* = M + Vs (T). In the spherical case, the V depends only on the radius. We havechosen the phase convention of the vector sphericalharmonics as:
(2)

(4)

We can discuss the approximation of the pseudospin symmetry by considering the equation of the small
component. For this purpose, the recently developed
Relativistic Hartree-Bogoliubov (RHB) theory in coordinate space has been used. 4) We find that the degreeof the degeneracy improves if the corresponding levels are less bound. In 88Zr , as the 2d3 / 2 and 381/2,
2d 5 / 2 and 197 / 2 pairs are near the fermi surface, sothat their splittings are very small. Similar cases for
120Zr are also observed.
The pseudo-spin symmetry is examined for the firsttime in realistic nuclei in the framework of RHB.4)
We have found a more general condition for the hidden pseudo-spin symmetry from the Dirac equation forthe lower component: i.e., dVjdr = 0, which includes
V = discussed in Ref. 3 as a special case. From thesimple Dirac equation, i has been shown that there are
two equivalent ways to solve the coupled Dirac equation for the upper and lower components: the normal
spin or pseudo-spin formalism. Solving the reduced
uncoupled differential equations for the lower component is the same as that for the upper component, as
the eigenvalue obtained is the same. The relation between the upper and lower components indicates thatthe unitary transformation from the conventional topseudo-spin formalisms has the "p-helicity". By studying the splitting caused by the pseudo-spin orbital potential, the quality of pseudo-spin symmetry in realistic nuclei is examined. For a given angular momentum and parity channel, the centrifugal barrier multiplied by the factor E - V becomes stronger for theless bound level, so that the pseudo-spin symmetry
for the weakly bound state is better than the deeply
bound state. This is in agreement with the experimental observation 1,2) and with the former model study toassume a spherical square potential-well. 3 ) The above
conclusion has been well supported by the examples of
88Z r and 120Zr.

°

where

+ 1,
I' = 2J. - I = { I1-1,

j = I + 1/2
jI - 1/2=(3)

Here, If is nothing but the pseudo-orbital angular momentum. After some tedious simplification, one reaches the radial equation of the lower component:
Physik-Department cler Technischen Universitat Miinchen,
Germany

References
1) A. Arima, M. Harvey, and K. Shimuzu: Phys. Lett. B
30, 517 (1969).
2) K. T. Hecht and A. Adler: Nucl. Phys. A 137, 129(1969).
3) J. Ginocchio: Phys. Rev. Lett. 78,436 (1997).
4) J. Meng and P. Ring: Phys. Rev. Lett. 77, 3963 (1996).

17

RIKEN Accel. Prog. Rep. 31 (1998)

Double Giant Quadrupole Resonance
H. Kurasawa* and T. Suzuki[Giant resonance]
The double giant quadrupole resonance (DGQR) has
been observed with nuclear interaction using heavy
ion beams at intermediate energies. 1) Recent experiments on (7r+, 7r-) and relativistic heavy ion reactions
have also revealed the existence of the double giant
dipole states (DGDR) in various nuclei. 1) The giant
resonance states are characterized by their excitationenergy, width, and excitation strength. Emling et al.l)have summarized the experimental data, and found
the relationship of the excitation energies and widthsof DGDR and DGQR to those of the single giant resonance states (GDR and GQR), as W2 = (1.91 ±0.02)Wland r 2 = (1.60±0.03)r 1 . Here, W2 (WI) stands for theexcitation energy and r 2 (r 1 ) the width of the double
giant resonance state (single giant resonance state).
They have also compared the strength of double giant resonance states with various theoretical values,
and found that all the theoretical values obtained so
far underestimate the data by more than a factor of
2. Contrary to DGDR, the strength of GDR is wellknown to be reproduced by the Thomas-Reiche-Kuhn(TRK) sum rule.
In Ref. 2 , we have derived the model-independent
sum rule for DGDR strength which corresponds to
TRK sum rule. We have shown that the excitationenergy and width of DGDR are well understood modelindependently, but the sum rule value is only a half ofthe experimental one. As far as we know, this disagreement has not been solved yet.
We can also derive the sum rule for the DGQR
strength, although some assumptions are required. Let
us define the strength function of DGQR as

the energy-weighted sum can be expressed in terms ofthe double commutator,s~l) = ~ (01[Q2, [H, Q2)]10).

(5)

The commutator with Q2 is rewritten with Q ass~1) = ~(0 I Q2[Q ,[H, Qll+2Q[Q , [H,QllQ+ [Q , [H , Q]]Q2 10).

(6)

When we assume [Q, [V, Q]] = 0, as in TRK sum rule,
we obtain:S~l) = L(Ef - Eo)IUIQ210)12f= ~{2(0 I Q2MI0) + (0IQ3 10 )},

(7)

m

r;.

where M is defined by M = L~=l
If we assume
furthermore that the nucleus is spherical and that
(0I Q2 In )(nIMI0) = 0(In) -110»,(8)then Eq. (7) is expressed in terms of the sum rules of
GQR,S~l) = 4siO) sill ,(9)where siO) and sF) are described as,2sill = I:(En - Eo)l(nIQ I0) 1 ,

(10)

(11)

Now we define the mean energies of DGQR and GQR
by using the energy-weighted and non energy-weighted
sum rules,
W2(1)= s(1)/s(O)22'W= S(l)/S(O)I l l '

(12)

Then, the sum rule in Eq. (9) gives
where A f is given by
Af

=

L

W2

UIQln)(nIQIO) = UIQ210) ,

(2)

x7 -

with Q = L~=l (2z; yf) . For this function thenon energy-weighted and energy-weighted sum rules
are given as(3)S~l) =

I:(Ef -Eo) IUIQ2 10)12 .

(4)

WI

{SiO)}2
=4~.

(13)

2

Thus the ratio of DGQR strength to GQR one is related to that of their excitation energies. If we takethe experimental value W2 ~ 2W1, Eq. (13) gives(14)

This result contradicts the experimental value by factor 2, as in the case of DGDR.2) It is very importantto understand this disagreement in nuclear physics.

f

The non energy-weighted sum over If) should not include the ground state 10), but the energy-weighted
sum can include 10) as well as If). Because of this fact
Department of Physics, Faculty of Science, Chiba University

18

References
1) H. Emling: Prog. Part. Nucl. Phys. 33, 729 (1994); Ph.
Chomaz and N. Frascaria: Phys. Rep. 252, 275 (1995).
2) H. Kurasawa and T, Suzuki: Nucl. Phys. A 591, ' 374(1996) .

RIKEN Accel. Prog. Rep. 31 (1998)

Possible Enhancement of the El Decay Rates
of Double Giant Dipole States t
V. G. Soloviev,* A. Arima, and N. Dinh Dang
[Double-giant dipole resonance, El decay rates]
The electromagnetic excitation of the double giant
dipole resonance (DGDR) in relativistic heavy-ion reactions has been studied in a wide range of nuclei. The
observed excitation energy of the DGDR is about twice
as much compared to the energy of the giant dipole resonance (GDR). The observed width of the DGDR islarger than the GDR width by 1.6 times. l ) The moststriking point is that the strength of the DGDR was
found strongly enhanced as compared to any theoretical estimations available so far. Among theoreticalstudies, which have been devoted to the description of
the DGDR states, we notice Ref. 2, where the generalproperties of the DGDR were treated making use ofa sum rule approach. One of the major results obtained in Ref. 2 is, if the mean energy of the DGDR
is twice as much compared to the GDR energy, the
DGDR strength is larger than that of the GDR by afactor of.j2. It means that there is a discrepancy between the strength of DGDR determined by the sum
rules and the experimental systematics.
The aim of the present work is to study a possibility
for the enhancement of the El decay as well as excitation. of DGDR in a two-step process. The present
paper shows that:(:t) the El transition rates from the DGDR statesto the GDR ones can be enhanced as compared tothose between the two-dipole-phonon components inwave functions of the DGDR states and the one-dipolephonon components in wave functions of the GDR
states. This enhancement can be observed experimentally in the ,-decay spectra of the El transition fromthe DGDR to the GDR.
(2) it is possible to expect an enhancement of the
DGDR states, which are formed in a two-step process of two consequent El transitions rather than in a
Coulomb excitation.
The observation of the DGDR may also serve as asignature of order in chaos, which takes place at suchhigh excitation energies in nuclei.
References
1) T. Aumann et al.: Phys. Rev. C 47, 1728 (1993); R.
Schmidt et al.: Phys. Rev. Lett. 70, 1767 (1993); H.
Emling: Prog. Part. Nucl. Phys. 33, 729 (1994); Ph.
Chomaz and N. Frascaria: Phys. Rep. 252, 275 (1995);
J. Stroth et al.: Nude. Phys. A 599, 307c (1996); K.
Boretzky et al.: Phys. Lett. B 384, 30 (1996).
2) H. Kurasawa and T. Suzuki: Nucl. Phys. A 597, 374(1996) .

Condensed from the article in Phys. Rev. C 56, R603 (1997)
Bogolyubov Laboratory of Theoretical Physics, JINR,
Russia19

RIKEN Accel. Prog. Rep. 31 (1998)

Possible Deviation of the Sum of Strengths for Double Giant
Dipole Resonance from Harmonic Oscillator Limit t
N. Dinh Dang, A. Arima, V. G. Soloviev,· and S. Yamaji[Double-giant dipole resonance, Harmonic ocsillators' limit]
The recent observation of the double giant resonance dipole (DGDR) in relativistic heavy-ion reactions of a wide range of nuclei has attracted a considerable attention. 1 ) The observed excitation energy of
the DGDR is about twice as much compared to theenergy of the giant dipole resonance (GDR). Its widthis larger than that of GDR by 1.6 times. While theseparameters of the DGDR are in a good agreement withthe representation of the multiphonon giant resonance,
which is formed by non-interacting harmonic oscillators, the most striking point is that its strength has
been found to be strongly enhanced as compared to
any theoretical estimations available so far. Recently,
making use of a sum rule approach, K urasawa andSuzuki 2 ) have demonstrated that, if the mean energyof the DGDR is twice as much compared to the GDR
energy, the DGDR strength is larger than that of the
GDR by a factor of.;2. Thus, there is a discrepancy
between the strength of the DGDR determined by thesum rules and the experimental data.
In the present paper we have shown the importanceof the part containing the products of the particle particle (pp) and hole - hole hh pair operators (theso-called scattering terms) of the nuclear Hamiltonian
in calculating the energy weighted sum of strengths(EWSS) for the DGDR. This part is known to have alittle influence on the phonon energy within the random phase approximation (RPA) except for only thelowest levels in transitional and deformed nuclei. In
the region of the GDR the contribution of this partis negligible. This is the reason why it has been neglected in all microscopic calculations of the GDR sofar. The present paper shows that it is no more allowed in the study of the DGDR. Even though the pp

Condensed from the article in Phys. Rev. C 56, 1350 (1997)
Bogolyubov Lab. of Theor. Physics, JINR, Dubna, Russia

20

and hh pair operators cannot be expressed exactly interm of ph phonon operators, one can use the exact
commutation relations of the former and the latter.
The complete EWSS for the DGDR has been derived
here for the first time, and a possible deviation fromthe value of this EWSS in the harmonic limit has beenfound. The formalism has been tested within a framework of a degenerate two-level model, where the RPA
has the simplest analytical solution. We found an example when this deviation is quite large and enhances
strongly the EWSS for the DGDR at various particle
numbers, while the EWSS for the GDR itself and theenergy of GDR change only slightly.
The present study, even though by the numericalcalculations within a schematic model, shows that it isdecisively important to include the full nuclear Hamiltonian in the study of the DGDR because some partof the Hamiltonian, while having a small influence on
the GDR, may affect strongly the DGDR characteristics. It also shows that the DGDR is not a superposition of independent harmonic oscillators, but a complex of interacting multiphonon configurations. The
latter makes the DGDR properties strongly deviatedfrom the harmonic picture.
References
1) T. Aumann et al.: Phys. Rev. C 47, 1728 (1993); R.
Schmidt et al.: Phys. Rev. Lett. 70, 1767 (1993); H.
Emling: Prog. Part. Nud. Phys. 33, 729 (1994); Ph.
Chomaz and N. Frasearia: Phys. Rep. 252, 275 (1995);
J. Stroth et al.: Nude. Phys. A 599, 307e (1996); K.
Boretzky et al.: Phys. Lett. B 384, 30 (1996).
2) H. Kurasawa and T. Suzuki: Nuel. Phys. A 597, 374(1996).

RIKEN Aceel. Prog. Rep. 31 (1998)

Constrained GCM Calculations Based on 3D-CHFB
T. Horibata, M. Oi, and N. Onishi[Tilted rotation, Generator coordinate method]
We have been carrying out a systematic calculation
based on a self-consistent three-dimensional Cranked
Hartee-Fock-Bogoliubov (CHFB) method in A '" 180region and have found a solution which represents a
Tilted Axis Rotating (TAR) state. 1 ,2) Then, an effectof a quantum tunneling between the two TAR wells
located symmetrically with respect to an equator is
expected. By taking into account the effect we tried
to describe the excited bands in terms of the twodimensional Generator Coordinate Method (GCM)3,4)
in which the north-latitude along the prime meridian
and the east-longitude along the equatorial line were
employed as the generator coordinates. ' The method
was a quite general and interesting approach in describing the bands as well as the yrast. However, we
could not obtain the stable plateau in the GCM calculation. The reason will be attributed to the factthat we lost much information concerning the highfrequency part of wave functions which are containedin the states with small eigen values of the norm kernel. This can mostly be taken into account throughangular momentum projection of HFB states. 5 ) Calculations along this line are in progress separately frompresent work.
Generally, in the process of solving the GCM equation the expectation values of angular momentum andthe particle number will be shifted from the values of
the CHFB constraints. To maintain the correct configuration of wave functions we restrict the expectation
values of the angular momentum and particle number
to their correct values during the process of solving
the GCM. We solve the following constrained GCMequation,' " [H

L..Jk,k' -\ (o)N T
ATk,k' -

1/(0)J2

t'"

k ,k'

] g(o) -k'--44.5 L---'----_---'--_--'-_......L.._--'-_---'-_---'-_J,.,.....i_--L.I...J
20
25
30
35
40
45
50
55
60
Number of Sl8Ies

Fig. 1. GeM solutions without constraints.

Energy Eigen Values of HiM·Wheeler Equa1ion

·223

I

·223.5c.......... .......... .

..

I--

I:" ....:-,

J -224cW:::::, ..

c.·." ........

t ~·'· : -··.

~~=---------.'._7... ~.~,_, . . . .,,224.5 fc·",.

r----~-225.5-. . . _--- ...

------'~"""",c':",>

·225

--

~

Iwtth

-

:--....

~~::~:"·". .c.:~.:~.::""--~.::::::'" ,;':::::.

:"",'"

0[;~;;~.:.;:..::::::::~ h.... ; ....

1
20

25

30

35

40

Number of slales

45

50

55

60

Fig. 2. GeM solutions with constraints.

E(o)g(o)k'k'

We show the results without constraints (Fig. 1) andwith constraints (Fig. 2) for the case of J = 18 Ii of
1820S. In Fig. 1 we can see that two lowest solutions
are almost degenerate and the next higher states lay
more than 1 Me V higher positions. The solutions do
not consist any stable plateau. In Fig. 2, however,
we can find relatively stable plateaus. The energy
splittings among the states are in the range of 10- 100
KeV. These values are reasonable for the interpretation of any excited bands observed in this mass region.
The angular momentum fluctuation is included in the
wave function of a cranking model. As the value is~J2 '" 100 Ii in our calculation, we restrict the expec-

tation value of J2 to ",450 Ii. We found a rather stable
plateau in the case where the constraints are switchedon. Detail of the work will be published elsewhere.
References
1) T. Horibata and N. Onishi: Phys. Lett. B 325, 283(1994).
2) T. Horibata and N. Onishi: Nucl. Phys. A 596, 251(1996).
3) T. Horibata, M. Oi, and N. Onishi: Phys. Lett. B 355,
433 (1995).
4) T. Horibata, M. Oi, and N. Onishi: RIKEN Aceel. Prog.
Rep. 30, 20 (1997).
5) M. Oi, N. Onishi, N. Tajima, and T. Horibata: Phys.
Lett. B 418, 1 (1998).

21

RIKEN Accel. Prog. Rep. 31 (1998)

Exotic State of 3D-CHFB
T. Horibata and N. Onishi[Tilted rotation, Three-dimentional cranked HFB (3D-CHFB)]
A systematic calculation based on a self-consistent
three-dimensional Cranked Hartree-Fock-Bogoliubov(CHFB) method revealed a possible existence of a
Tilted Axis Rotating (TAR) state in A '" 180region. 1 ,2) In the previous calculations the force parameters were chosen so as to reproduce just the overall
features of low-angular momentum states of this mass
region. The observed first backbending in A '" 180region is considered to be due to i13/2 neutron states,
whereas in our calculation protons were playing therole. The reason was attributed to our slightly too
strong Q.Q force parameters. In the present calculation, therefore, we refine the force parameters so as toreproduce the observed characteristic features in the
yrast states of nuclei in the region. Moreover, we increase the accuracy of numerical calculation by performing a backward direction as well as a forward direction along the prime meridian. As a result of thecalculation we found the existence of a stable TAR
state in the region of e rv 25° as shown in Fig. 1. Although we do not have any experimental evidences for

O.S

0.4

'>

0.2

!

S
~

III

References

.0.2

.0.4
0

15

75

Fig. 1. Energy curves along prime meridian.

22

the existence of such states for now, this is a convincing
result that the TAR indicates certain new dynamics inthis mass region.
In the Fig. 1 we also find that the energy of thestates near the north pole (8 = 90°) is negative, whichmeans that the states around the north pole are lower
in energy compared with the Principal Axis Rotating(PAR) yrast state. The wave function of this state consists of the positive parity i13/2 neutron states. These
neutrons aligne their angular momenta to the symmetry axis and contribute to K = 8 band state. In theexperimental data we find K = 8+ bands in several nuclei in this mass region. These bands are interpreted
as a candidate of the t-band. 3 ) Therefore, the interpretation of the K = 8+ bands requires more precise
analyses from both sides of experiment and theory.
Furthermore, this time we find a new state justabove the PAR yrast state (8 = 0°): at about E = 150
Ke V higher than the PAR. This state has been obtained in the calculation of the backward direction
starting from e = 30°. The configuration of wave function changes drastically when the north latitude takes
the values at around 8 = 10° '" 15°. Second phasetransition occurs around 8 = 45°. When the backward
calculations starting from 8 = 60° are performed, we
found also new states in these angle regions. The curveis shown also in the Fig. 1.
Solving the Generator Coordinate Method on thesestates, including the new ones, will be much interesting. Detail of the results will be published in near
future.

1) T. Horibata and N. Onishi: Phys. Lett. B 325, 283(1994).
2) T. Horibata and N. Onishi: Nucl. Phys. A 596, 251(1996).
3) P. M. Walker: Proc. Int. Conf. on the Future of Nuclear
Spectroscopy, Crete, p. 134 (1993).

RIKEN Accel. Prog. Rep. 31 (1998)

Signature and Angular Momentum in 3D-Cranked HFB States t
M. Oi, N. Onishi, N. Tajima, and T. Horibata[NUCLEAR STRUCTURE: Angular momentum projection, 3d-cranked HFB, Signature]
We are interested in a relation between angular momentum and "signature", a symmetry of 1r-rotation
around the intrinsic I-axis. In the textbook by Bohrand Mottelson,2) the relation is given in the particlerotor model as

0.16
0.14

(aJ

0.12

'"= 0.1
0.08
0.08

(1)

0.04

where r, I and K denote the signature, total angular momentum and its projection onto the 3-axis (socalled "K-quantum number"), respectively. This implies that the even/odd members of rotational bands
are classified by the + 1/ -1 signature. This is quite favorable for the cranking model because the signatureis the only quantum number in the model. However,there is a question as to whether this relation can beapplied to the cranking model because this relation isderived in the context of the particle-rotor model. Usually, it is believed that the relation holds quite well evenin the cranking model. It is our major aim to examine
the validity of this relation in the cranking model.
In our study, cranked states are generated by
the three-dimensional Hartree Fock Bogolibov (HFB)
method. We solved the corresponding HFB equation
in a fully self-consistent manner (the gradient method).
Then, we use the exact angular momentum projection
technique.
2
What we need is the probability I(IM 1¢)1 , whereI¢) is a 3d-cranked HFB state. This can be calculatedby the angular momentum projection as follows: 2)00.12

r = (_1)1(when

K = 0) ,I(lM 11» 12 = T r [N1 j

(2)

1

=

L

NkK

(3)

K= - I= (1) 1Ph- K 11> ) .

(4)

Fig. 1 shows three pictures: (a) PAR (principal axis
rotation), t v one-dimensional cranking model; (b) TAR(tilted axis rotation), t v 3d-cranked HFB); and (c) signature projected TAR. As seen in (a), the relation (1)holds very well. The HFB state consists of only members with even angular momentum components, i.e. ,r = +1. The relation breaks down a little in (b). There
are two reasons for this: (1) Signature is broken downby tilting the angular momentum vector toward 3-axis
from I-axis; (2) Mixing with high-K components becomes larger than the case (a) because of tilting of theangular momentum vector.
To see which is more important, we make the signature projection, which is defined as follows:
Ir = ± ) = N (I+9) ± 1-9».

0.G1

20

25

Fig. 1. Probability distributions of (a) PAR, (b) TAR and(c) Signature Projected TAR.

angle and the same angular momentum constraint. In
Fig. l(c), we see how the signature projection works.
For a state with r = 1, the relation between angular momentum and signature seems to be recovered.
However, for a state with r = -1, we see no relation
between angular momentum and signature, i.e., evenand odd angular momentum components are mixed
completely.
Thus, there is no correlation between the signature
and angular momentum unless the states have a dominant K = 0 component. We also calculated the probability for each K components, and confirmed that theabove statement should be right. PAR, TAR or Signature projected TAR with r = 1 states has more than
50% of K = 0 components while signature projected
TAR with r = -1 has less than 0.1% of K = 0 components.
We conclude that the relation between angular momentum and "signature" is not a universal one, atleast, in the three-dimensional cranking model. Hence,
we must treat the angular momentum iIistead of thesignature in the general case. It is quite likely thata 3d-cranked HFB plus angular momentum projection
technique can describe more general nuclear dynamics,
i.e. , nuclear rotations beyond a mere cranking model.

(5)

Here , N is a normalization factor and I±O) is one of
3d-Cranked HFB states with positive/negative tilting
Condensed from the article in Phys . Lett. Bl)~

References
1) M. Oi et al. : Phys. Lett. B 418, 1 (1998) .
2) A. Bohr and B. Mottelson: Nuclear Structure (Benjamin, New York, 1969) .

23

RIKEN Accel. Prog. Rep. 31 (1998)

Doubly Periodic Motion in Superdeformed States
K. Sugawara-Tanabe and K. Tanabe*[Cm / n symmetry, i::l.I = 4 bifurcation, Superdeformation]
Recently, the 1::11 = 4 bifurcation in superdeformed
bands has been observed ,l) and has stimulated discussions on the nuclear structure. We have proposeda dynamical mechanism in the sense that the bifurcation originates from the periodicity of the intrinsic
wave function. 2 ) We start from a general microscopic
Hamiltonian H defined in the laboratory frame (L).
We assume a rotational motion with the rotationalfrequency of w(t) , which is decomposed into two components; one with the constant rotational frequency
Wo pointing to the direction of the rotational axis 1,
and another with I::1w(t) which corresponds to the precessional motion caused by the small asymmetry. We
transform the L-frame into the body-fixed frame (B) by
employing unitary operators. Then, the corresponding Schrodinger eigenfunction at the B-frame is given
by I'lis (t) > B. In the interaction representation of
IwS(t) >B= exp( - iHBt)lwI(t) >B , we obtaina I
Ii atlw (t) >B= [-WOII - I::1w(t)I llw (t) >B·(1)

An important remark is that Eq. (1) has the periodicity of Tp and is invariant under the transformationof T = exp(ivTp 8/8t) with integer v, when the precessional angular frequency I::1w(t) has the value of wp
related to Wo through wo/wp = Tp/TO = A. Thus, especially when these two periods are commensurable sothat the ratio can be expressed as A = min « 1)
in terms of two irreducible positive integers m and n ,the nuclear system comes back to its original positionand direction after the time-lapse nTp. In other words,
T lw I (t) > B obeys the same Eq.(l). Thus, the invariant solution describing the doubly periodic system canbe constructed by summing up a finite series of interfering terms with different hysteresis.
Now , we solve Eq. (1) in the perturbation approximation up to the first order of I::1w(t) , and thengo back from B-frame to L-frame. We identify thestate IWH > L in the Heisenberg representation at Lframe (= exp(iHt) lwS(t) >L) with lIMa >L, andIWI(O) >B with lIMa >B, where a corresponds to

Department of Physics, Saitama University

24

h = K for the case of axially symmtric deformation(uniform rotation). Finally we obtain the wave function of the Cm / n -type.

lIMa >L =x

LM' DitM'(O) [1 + i C2

~ (PvFv + FvPJ) ] 11M'" >B, (2)where C is calculated from Wo, wp and three kinds ofmoments of inertia; Pv as a function of woh VTp is thenormalization so that it reduces to the axially symmetric solution in the limit of I::1w = 0; and Fv is givenby. (27rmv)- n- 12 + (1 - cos (27rmv))-nh· (3)Fv = s'tn

The energy difference between with and without adouble periodicity up to the first order of I::1w is calculated by using Eq. (2). As a simple example, we adopt
the triaxial rotor Hamiltonian. We choose n = 4 andm = 1 ( C 1 / 4 -type ), which reproduces the experimental datal) quite well. Similar numerical analysis was
performed also for the C 1 / 3 -type (n = 3, m = 1) symmetry, and the result predicts the 1::11 = 6 trifurcation
as a new possibility. From the relationship between
Wo and wP ' we can show that there exists a domain ofallowance for the stability of the state of Cm/n-type insuch a way that lo(wo/wp)1 < 1/n2. The E2 transition
rate calculated from Eq. (2) yields the reduced transition probability value B(E2) which deviates from theordinary result for the axially symmetric rotor only inthe second order of energy shift.

References
1) S. Flibotte et al.: P hys. Rev. Lett. 71, 4299 (1993); D.
S. Haslip et al. : Phys. Rev. Lett. 78, 3997 (1997) .
2) K. Tanabe and K . Sugawara-Tanabe: Proc. Int. Symp.
on Symmetries in Science X , 1997-7, Plenum Press inpress.

RIKEN Accel. Prog. Rep. 31 (1998)

Triaxial Nuclei in Relativistic Mean Field Theory
S. Sugimoto, K. Sumiyoshi, D. Hirata, and H. Toki
[Relativistic mean field theory, Triaxial deformation, 124Ba]
We study the properties of heavy mass nuclei including the possibility of triaxial deformation in therelativistic mean-field theory. We calculate the energy
surfaces of about thirty even-even nuclei around 122Xein the (3, plane on the Fujitsu VPP500/28 Supercomputer of the Computation Center in RIKEN.
The relativistic many-body theory has been extensively applied to nuclei and nuclear matter with remarkable success in recent years. Hirata et al. l ) used
its phenomenological version, the relativistic meanfield theory (RMF), to study the ground-state properties of the stable and unstable nuclei with axial deformation, and found the results very satisfactory. However, they found it necessary to extend the theory toinclude a triaxial deformation. In many nuclei the axial symmetric calculations give the energy curve as afunction of the (3 deformation parameter, which has
minima on both the prolate and oblate sides with energies very close to one another. For such a nucleus
they cannot firmly conclude which shape it has as theground state. Such a nucleus may have another typeof deformation. Therefore, they added one more degree of freedom C)' deformation) to their theory, andapplied it to the light mass nuclei. 2) In the calculations
they found the consistent results with axially symmetric deformation code, and found for the sulfur isotopes
42-56S a smooth transition from prolate through triaxial to oblate shapes and finally spherical shape.
Since the similar importance of the triaxial shape is
expected, we calculate the energy surfaces of about
thirty even-even nuclei around 122Xe, Z = 50-58,
N = 64-72 region to study the structure of shapetransition of nuclei from prolate to oblate shapes.
In the transition process, the triaxially deformed
and/or gamma soft nuclei may emerge. We use the
RMF theory which is extended to include the triaxial
deformation. 2) The RMF theory contains the meson
masses, the meson-nucleon coupling constants, and themeson self-coupling constants as free parameters. We
use the parameter set called TMA 3) whose parameters
have mass number dependence and which has been obtained to reproduce quantitatively nuclear properties
in entire mass region. The wave functions of nucleons
and mesons are expanded in terms of the eigenfunctions of an triaxial deformed harmonic oscillator potential. The expansion method is described in detailin the paper by Gambhir et al.,2,4) but one more degree of freedom (-y deformation) is included newly.2)

In the present calculation, we work with basis of the
12 major shells for fermions and 10 major shells forbosons. In order to obtain the energy surfaces, we
perform the quadratic constrained calculations on thequadrupole moments of nucleon distribution, Q20 and
Q22. 2,5) We note that we do not take the pairing correlations into account, although they play an important role for nuclear deformation. The investigationsof how to incorporate them in the RMF theory are now
in progress.
Figure 1 shows the energy surface of 124Ba in {3,plane. The horizontal axis (, = 0°) denotes prolate
shape and the tilted axis (, = 60°) denotes oblate
shape. The region among these axes denotes triaxiallydeformed shape. The larger value of {3 indicates thestronger defomation. In Fig. 1 the position of absolute
minimum is denoted by the black area. From the figure
we can see that 124Ba may have the triaxially deformed
shape in the ground state. For the other nuclei wecalculated, we have found many interesting structures,and we are now investigating these results.
y .. 60·

0.0

0.2

0.4
~cos (y)Fig. 1. The energy surface in the (3, plane of 124Ba.
The positon of the absolute minimum is denoted by
the black area. This figure indicates that 124Ba has atriaxial shape.

References
1) D. Hirata et al.: Nucl. Phys. A 616, 438c (1997).
2) D. Hirata et al.: Nucl. Phys. A 609, 131 (1996).
3) Y. Sugahara: Doctor thesis, Tokyo Metropolitan University (1995).
4) Y. K. Gambhir et al.: Ann. Phys. 198, 132 (1990).
5) H. Flocard et al.: Nucl. Phys. A 203, 433 (1973).

25

RIKEN Accel. Prog. Rep. 31 (1998)

The Deformation Effect on the Pairing Gap
K. Sugawara-Tanabe, N. Yoshida, and A. Arima[Deformation, Pairing gap, HFB, BCS]
It has been discussed that the pairing gap is decreased by several effects, for example by Coriolis antipairing effect,l) thermal effect 2) and density effect. 3 )Here, we propose another new effect that decreases
the pairing gap, i.e., deformation effect. It is wellknown that the pairing interaction favors the spherical shape, while the quadrupole interaction favors thedeformed shape. Comparing with the form of themean-field in the case of Coriolis anti-pairing effect orwith that in the case of thermodynamical potential, we
find a similarity for the case of deformed mean-field.
In the other words, the intensive variable corresponds
to rotational frequency, temperature and the strengthof the quadrupole field, while the extensive variablecorresponds to an angular momentum, entropy andquadrupole field.
Stimulated by this analogy, we have performed therealistic calculations for 152Dy using the Nilsson plus
Bardeen-Cooper-Schrieffer (BCS) calculation for N =3, 4, 5 and 6 shells (148 levels), and also the constrained Hartree-Fock-Bogoliubov (HFB) calculation
which is self-consistent but for smaller single-particle
space (64 levels in proton and 88 levels in neutron).
Both calculations give a decrease of the pairing gap(.6.), as a function of the deformation parameter (8) or
the strength of the quadrupole field (X).
I t is usually believed that the decrease of .6. as afunction of <5 is caused by a change in the level density.
We have calculated the number of levels in the regionsof A ± 2 Mev and A ± 4 Mev for the cases of <5 = 0.2, 0.4
and 0.6. The results gave almost the same number oflevels, which supports that the level density is constantin this region of the deformation. We have also calculated the level density in the schematic model which
neglects the £ - sand £2 interactions in the deformed
Nilsson potential. For <5 = 0 and <5 = 0.6, we can calculate the level density analytically, and obtains a nearly
constant value independent from 8. Thus, we can conclude that G p = C independent from the deformation,
where G is the strength of the pairing interaction andp is the level density.
The HFB equation reduces to the Nilsson plus BCS
equation if we set A iJ.L = <5iJ.LuJ.L and BiJ.L = vJ.L<5iJ.L' where

26

AiJ.L and BiJ.L are the forward and backward amplitudes
in the generalized Bogoliubov transformation from thespherical base (i) to the deformed base (p,), respectively. However, there remains a difference in the selfenergy term. The main difference between the Nilsson
plus BCS calculation and the HFB calculation is theself-consistency. The self-energy term in the HFB becomesr;;(3 = -X( r2Y20)a(3 I:(r2Y2o)I'I'V~,

(1)

l'

where v~ is the the occupation probability at the level,. Equation (1) indicates that the deformed field is
influenced by the pairing field. On the other hand, theself-energy term in Nilsson is given by(2)
which is completely independent from the pairing field.
Thus, we treat the difference between (1) and (2) asa perturbed term, i.e., r~lJ = r:;(3 - r;:(3 based on
the Nilsson plus BCS basis, and carryon the similar perturbation calculation as done by Mottelson andValatin 1) for the case of Coriolis anti-pairing. Contrary to Coriolis anti-pairing effect, there remains thefirst order perturbation term.

Here ~a is the single-particle energy measured fromthe chemical potential and= ~; + .6. 2. Similarly,
the second order perturbation term was carried out as.6. (2) . The numerical results show that both of .6.(1)and .6. (2) decrease with increasing 8.

E;

References
1) B. R. Mottelson and J. G. Valatin: Phys. Rev. Lett . 5,
511 (1960).
2) K. Tanabe and K. Sugawara-Tanabe: Nucl. Phys. A
357, 20 (1981).
3) A. Bohr and B. R. Mottelson: Nuclear Structure (Benjamin, New York, 1969).

RIKEN Accel. Prog. Rep. 31 (1998)

Thermal Damping Width of Giant Dipole
Resonance in Hot Nuclei t
N. Dinh Dang and F. Sakata*[Thermal damping, Hot giant dipole resonance]
A great interest has been devoted to the propertiesof highly excited nuclei produced in heavy-ion fusion
reactions during the last decade. Analyzing the decay
pattern of these hot nuclei, the giant dipole resonance(GDR) built on compound nuclear states has been
observed. I) The experiments have shown that whilecentroid energy of the hot GDR is almost independentof excitation energy (or of temperature T), its apparent width increases significantly as the excitation energy goes up and saturates at around 130 Me V in Sn
isotopes. This attractive phenomenon has become areal puzzle to be resolved for many theoretical studies in recent years. Indeed, while most of theoretical
approaches agree in reproducing the centroid energyof the GDR at T i= 0, many of them are still in contradiction with each other in understanding the GDR
width in hot nuclei.
As the temperature increases the quantal effects arising from a great number of non-collective degrees of
freedom are expected to diminish, which means thatthey reach the thermal equilibrium much faster than arelatively smaller number of collective degrees of freedom. In the case of the hot GDR, the collective degrees
of freedom are the ph phonon states, while the pp andhh configurations consist mostly of non-collective degrees of freedom. The collective degrees of freedom areexperimentally relevant , while the non-collective ones
are constituting a background, to which the collective
degrees of freedom are coupled. If the background isvery large it can be considered as a heat bath, andthis coupling between collective and non-collective degrees of freedom becomes irreversible. It leads to thethermal damping of the collective ph phonon states,
associated with the hot GDR, when these phonons arepropagating through the heat bath.
We present an approach which allows to derive thethermal damping width of the GDR in hot nuclei in a
microscopic way. We demonstrate the importance ofthe thermodynamical effects in the non-collective pp
and hh configurations, which appear only at non-zerotemperature and can play the role of a background or aheat bath. Namely, we have pointed out that the irreversible coupling of the ph GDR to this background(or heat bath) leads to the thermal damping of GDR in
hot nuclei. The application of our approach to a simple
schematic model has shown that this thermal damping mechanism can be complementary to other mechanisms in understanding the behavior of the GDR width
at finite temperature. Finally a semi-microscopic unification of the quantal spreading with the integrated
thermal damping widths shows that the behavior of
the total width found in this approach is similar to
the trend in the experimental findings in hot Sn isotopes including the region of width saturation. Our
analysis has been performed within an oversimplified
schematic model. A drawback of this model is, while
the GDR can be described by one single collective phtransition, the degeneracy of non-collective pp and hh
configurations on only two levels made them too collective and therefore artificially enhanced the intensityof the low lying mode. In realistic situations we expect that a very large number of non-collective pp andhh degrees of freedom will spread out the strength distributed on them. Nonetheless, since the mechanismof the thermal damping arises from the coupling between collective and non-collective degrees of freedom,
we believe that the qualitative conclusion of our formalism on the behavior of the hot CDR, including theregion of width saturation, is model-independent.
References
1) Proc. Gull Lake Nucl. Phys. Conf. on Giant Resonances:Nucl. Phys. A 569 (1994), (edited by M. Thoennessen);
J. J. Gaardh¢je et al. : Phys. Lett. B 139, 273 (1984);
J. J . Gaardh¢je et al.: Phys. Rev. Lett. 53,148 (1984);
J. J. Gaardh¢je, A. M. Bruce, and B. Herskin: Nucl.
Phys. A 482, 121c (1988); C. A. Gossett et al. : Phys.
Rev. Lett . 54, 1486 (1985); D. R. Chakrabarty et al.:Phys. Rev. C 36, 1886 (1987); D. R. Chakrabarty: Nucl.
Phys. A 382, 81c (1988); R. J. Vojtech et al.: Phys. Rev.
C 40 , 2441 (1989) ; A. Bracco et al.: Phys. Rev. Lett.
62, 2080 (1989); A. Bracco et al.: Nucl. Phys. A 519,
47c (1990); G. Enders et al.: Phys. Rev. Lett. 69, 249(1992) ; H. J. Hofmann et al. : Nucl. Phys. A 571, 301(1994); J. H. Le Faou et al.: Phys. Rev. Lett. 72, 3321
(1994).

Condensed from the article in Phys. Rev. C 55, 2872 (1997)
Department of Mathematical Sciences, Ibaraki University

27

RIKEN Accel. Prog. Rep. 31 (1998)

Relation between the Damping of the Hot Giant Dipole Resonanceand the Complex Admittance of an Irreversible Process
N. Dinh Dang and F. Sakata*[Damping wdiths, Hot giant dipole resonance, Complex admittance]
At present we see two particular important issues
in the theoretical study for the behavior of the giant
dipole resonance as a function of temperature. The
first issue is the need in a consistent description of the
hot GDR width as a function of temperature, including both regions of the width's increase at low temperatures (0 ~ T ~ 3 MeV) as well as of the width's
saturation (T ~ 3 MeV) up to the region where the
GDR is thought to disappear (T > 4.5 "-' 5 MeV).
The second issue is the relation between the microscopic and macroscopic understandings of the damping
mechanism of hot GDR. Recently we have shown in aseries of works that the coupling of the phonon in the
random phase approximation (RPA) to the pp and hh
configurations, which appear at nonzero temperature,leads to the thermal damping of the collective vibration (phonon). In our most recent work,l) we gave ouranswer to the first issue. Namely, we have performed asystematic study of the damping of the GDR in 90Zr,
120Sn and 208Pb as a function of temperature T. The
results have shown that the coupling of collective vibration to the pp and hh excitations, which causes thethermal damping width, is responsible for the increaseof the total width with increasing temperature up to
T ~ 3 Me V, and its saturation at higher temperatures.
Our results are found in an overall agreement with theexperimental data for the GDR width, obtained in the
inelastic a scattering and heavy-ion fusion reactions at
excitation energies E* :s. 450 MeV.
In the present paper we propose an alternative
method to calculate the damping width of the hot
GDR via the complex admittance of an irreversible
process. The relation between the microscopic theory
for the damping of hot GDR and the macroscopic one
for the evolution of the dynamical variable, which describes the evolution of the hot GDR, is established.
The microscopic expression for the complex admittance is derived from the Green function, describing
the propagation of the GDR vibration through thefield of noncollective degrees of freedom (heat bath).
The present formalism was then applied to a systematic study of the behavior of the GDR as a functionof temperature in the nuclei l20Sn and 208Pb. The
values of the calculated damping width r CDR of the
hot GDR, centered at ECDR(T), were compared withthe recent experimental data obtained in the heavyion fusion reactions and inelastic a scattering. An
overall agreement between theory and experiment isachieved. As compared to the recent predictions byother theories,2) the present approach, which is freefrom the constraint on adiabaticity, seems to be able
to give a better agreement with experiment, and can
Department of Mathematical Sciences, Ibaraki University

28

0.8

~ 0.6
a:

o

; . 0.4

0.2

5

10

15

20

25

30

111 (MeV)

Fig. 1. The probability IWCDR(t)1 2 for the GDR in 120Sn
as a function of the inversed time lit = r CDR at various
temperatures. The value of the temperature (in MeV),
at which a curve was calculated, is given by a number
near the curve. The horizontal line is exp( -1).

cover a much larger temperature interval, including. the region of the width's saturation, where the adiabaticity is broken. The present work confirms that thethermal effects due to the coupling of the GDR collective vibration to the pp and hh configurations are
the source of the increase of the GDR's width at low
excitation energies (up to 130-150 Me V) and in thewidth's saturation at high excitation energies (see Fig.
1) . These effects are fairly enough to account for thethermal fluctuations in the hot GDR in finite nuclei.
The quantal width r Q due to the coupling of the GDR
to only ph configurations decreases slowly with increasing temperature T. Analyzing the calculated strength
distribution of the hot GDR, we see that refined experimental methods are needed to explore the low-energy
region of the GDR distribution in order to isolate apossible low-lying structure. In particular, the appearance of the low-lying structure and the difficulties ofextracting it from the background are proposed in thiswork as one possible reason of the "disappearance" ofthe hot GDR in some experiments. On the other hand,a more refined study on the relationship between the
excitation energy and temperature in finite nuclei attemperatures below T = 5 MeV is needed in order
to avoid the large uncertainties when comparing theoretical results and the data. Finally, our results seemto indicate the presence of motional narrowing in the
hot GDR at T ~ 1-1.5 MeV as a consequence of thequantal coupling to ph configurations.
References
1) N. Dinh Dang and A. Arima: RIKEN Accel. Prog. Rep.
31, 29 (1998).
2) R. A. Broglia et al.: Prog. Part. Nucl. Phys. 28, 517(1992); A. Bonasera et al.: Nucl. Phys. A 569, 215c
(1994); W. E. Ormand et al.: Phys. Rev. Lett. 11, 607(1996); W. E. Ormand et al.: Nucl. Phys. A 614, 217(1997).

RIKEN Accel. Prog. Rep. 31 (1998)

Temperature Dependence of Quantal and Thermal
Dampings of Hot Giant Dipole Resonance
N. Dinh Dang and A. Arima[Quantal and thermal damping witths, Hot giant dipole resonance]
The study of the Giant Dipole Resonance (GDR),
built on compound nuclear states (hot GDR), has been
the subject of a considerable number of works during
the last 15 years (See Ref. 1 for the reviews). The mainfeature of the hot GDR phenomenon can be summarized as follows. The energy of the hot GDR is about
the same as of the one built on the ground state (g.s.)(the g.s. CDR). It can be well described within theframework of existing theories. However, its width
increases rapidly as increasing the excitation energy
E* (or temperature T) up to around 130 MeV in Sn
isotopes. At higher excitation energies the width increases slowly and even saturates. Recently two newexperimental methods, involving compound nuclear reactions and inelastic a scattering,2) have opened a possibility to study individually the effects of thermal fluctuations and of the angular momentum on the dampingof the hot CDR. The most recent theoretical evaluations in Ref. 3, which include the thermal shape fluctuations within an adiabatic model, agree nicely withthe a-scattering data in Ref. 3 for the CDR width in
120S n and 208Pb at temperatures 1 MeV < T < 3 MeV.
The region of the width saturation (E* > 130 MeV),
where a considerable number of heavy-ion fusion data
has been accumulated up to E* 450 MeV, is left out
in the description of Ref. 3. In the present situation, ofparticular importance in the theories of the hot GDR
is the understanding in a consistent and microscopic
way the behavior of the the hot CDR as a function oftemperature in a large interval. Such a theory mustcover the region of the width's increase at low temperatures (0 ~ T ~ 3 MeV) as well as the region of thewidth saturation (T ?: 3 MeV) up to the region where
the CDR is thought to disappear (T > 4.5 5 MeV).
In this paper we present an approach using the
double-time Green function method to a systematictheoretical study of the width of the CDR as a functionof temperature in the nuclei 90Z r , 120Sn, and 208Pb.
The results are compared with the recent experimental data of the CDR width in heavy-ion fusion reactions and inelastic a scattering. An overall agreement
between theory and experiment is found (see Fig. 1).
This agreement is also better than those from recent
theories and covers a much larger region of excitation
450 MeV. For the first time theenergies up to E*
theory describes both regions of the width increase as
well as the width saturation in a uniform way. The
analysis in the present paper shows that: (1) Thermal
effects due to the coupling of the GDR collective vit"V

t"V

t"V

T (MeV)

Fig. 1. Width of GDR as a function of temperature T
for 120Sn. Experimental data of Ref. 2 are shown by
open squares. The dashed curve denotes the quantal
width r Q, calculated via coupling to ph configurations;the dotted curve stands for thermal width rT, calculated via coupling to pp and hh configurations; the solid
curve with diamonds represents the total width rGDR.
The solid curve is rGDR, calculated without the effectof single-particle damping. The dash-dotted and shortdashed curves represent the widths obtained within the
adiabatic model 3 ) without and including the evaporation width, respectively.

brat ion to the pp and hh configurations playa decisiverole in the increase of the GDR's width at low excitation energies (up to 130-150 MeV) and in the width's
saturation at high excitation energies. The effects ofcoupling to pp and hh configurations are fairly enoughto account for the thermal fluctuations in the hot CDR
in finite nuclei. The quantal width r Q, which is causedby the coupling of the CDR to only ph configurations,decreases slowly with increasing temperature T. The
region where the CDR width saturates can serve as ananalogue of a gradual transition from zero sound (g.s.
CDR) to ordinary sound (hot CDR) in finite nuclei atnonzero temperature. (2) The effects of single-particle
damping on the GDR width are small up to very hightemperatures. (3) A more detail study on the relation between the excitation energy and temperaturein finite nuclei at temperatures below T = 5 MeV iscalled for in order to avoid the large uncertainties in
confronting theoretical predictions and the data.
References
1) K. Snover: Annu. Rev. Nucl. Part. Sci. 36, 545 (1986);
J. J. Gaardh0je: Ann. Rev. Nucl. Part. Sci. 42, 483(1992).
2) E. Ramakrishnan et al.: Phys. Rev. Lett. 76, 2025
(1996).
3) W. E. Ormand, P. F. Bortignon, and R. A. Broglia:
Phys. Rev. Lett. 77, 607 (1996); W. E. Ormand et al.:Nucl. Phys. A 614, 217 (1997).

29

RIKEN Accel. Prog. Rep. 31 (1998)

Stability of the Thermal HFB Equation
K. Sugawara-Tanabe and K. Tanabe*[THFB, TRPA, Stability]
We have constructed the general formalism forthe thermal Hartree-Fock-Bogoliubov (THFB) equation and for the stability equation of THFB many
years ago. I) Then, the thermal giant dipole resonance(TGDR) has been observed experimentally, and many
papers have tried to solve the thermal RPA (TRPA)
equation in order to explain the width and energyof the THFB as a function of temperature. 2 ) Now it
becomes on the topic to discuss the stability of thethermal field, because TRPA equation depends on the
THFB solutions.
Thermal HFB equation is derived by minimizing thethermodynamical potential F with respect to the A ,Band f. Here, AkJ.L and BkJ.L are the forward andbackward amplitudes, respectively, in the Bogoliubovtransformation from the spherical base Ck to the deformed base aJ.L' while fJ.L is the quasiparticle occupation number defined byfexp( -f3H)- T t
J.L - ra aJ.L
J.L

Tr exp( -f3H).

Because of an additional freedom of the temperature

Since no one has ever made a success in solving thethermal stability equation self-consistently, we assume
following approximations as a first step.
(1) At first, the temperature is treated as an external parameter, although it should be determined selfconsistently.
(2) Secondly, we start from the axi-symmetrically
deformed Nilsson levels, instead of the spherical base
Ck· In this case, AkJ.L equals 6kJ.LUJ.L and BkJ.L equals
6kJ.LVJ.L' These two assumptions mean that we have neglected the self-consistency in solving thermal meanfield.
(3) Thirdly, we assume that the quadrupolequadrupole interaction is already included in the deformed Nilsson potential, and we treat only the pairing

30

(2)
where

x = S-WZ-IWT
Y = R - WZ-IW T .

(3)Here, Sand R are given as a function of f J.L' U J.L' v J.L'
quasi-particle energy EJ.L and the pairing strength G.
The matrix element of Z is given by

Z

- 6
kT
2
J.LV fJ.L(l- fJ.L) - G6J.Lv(UV)J.L

J.LV -

G 6 (44- 4"
J.LV UJ.L + VJ.L)'

(4)

(1)

T in the thermal mean-field, additional variational parameter fJ.L should be included. Consequently, the stability equation is derived through 62 F by the second
order variation of 6A, 6B and 6f.

Department of Physics , Saitama University

interaction as a remaining potential.
With these approximations, we obtain the stability
matrix as

where tilded v denotes the time-reversed state of v. If
the eigenvalues of Eq. (2) is negative, the solution of
THFB equation becomes unstable. The submatrices ofEq. (2), i.e. , X and Y parts in Eq. (2), are proved to
become a TRPA equation. 3 ) Thus, the stability equation of THFB is the product of TRPA-term with additional Z-term. This additional term gives a constraint
on the temperature with which the thermal mean-field
can have the physical meaning.
Now, as a next step, we are extending our calculation
to the more realistic case, without assumptions of (2)and (3). Our final goal is to eliminate assumption, i.e.,
the full self-consistent calculation.
References1} K. Tanabe, K. Sugawara-Tanabe, and H. J. Mang:
Nuel. Phys. A 357, 20 {1981} .
2) K. Sugawara-Tanabe and K. Tanabe: Prog. Theor.
Phys. 76, 1272 {1986}.
3) K. Tanabe and K. Sugawara-Tanabe: Phys. Lett. B
172, 129 (1986).

RIKEN Accel. Prog. Rep. 31 (1998)

Variation of Transport Coefficients for Average Fission
Dynamics with Temperature and Shape t
S. Yamaji, F. A. Ivanyuk,*! and H. Hofmann*2[Collective motion, Nuclear dissipation, Quasi-static thermodynamics]
We study a slow collective motion at finite thermal excitations on the basis of linear response theory
applied to the locally harmonic approximation. The
transport coefficients for average motion, such as, friction " inertia M , the local stiffness C, the inverse relaxation time {3 = ,/ M and the effective damping rate
TJ = ,/(2JMICI), are computed along a fission pathof 224Th within a quasi-static picture. The response
functions have been calculated within a realistic twocenter shell model. Effects of collisions have been accounted for by using self-energies having both real andimaginary parts. The latter are allowed to depend not
only on temperature but on frequency as well, in which
way memory effects of the collision term are simulated.
Locally collective motion is treated self-consistently, inthe sense that the structure of the associated response
resembles the one known from the RPA of undamped
motion.
Various procedures have been described to deducetransport coefficients from the microscopically computed response, which generalize previous descriptions.
They have been evaluated as a function both of temperature as well as of variation of the shape along thefission path. Considering all the effects taken into account, such a study has never been reported before.
The results found invite us to draw the following conclusions.
(1) Perhaps one of the most striking features is the
weak dependence of both (3 as well as of TJ on the shapeparameter, as encountered here along the fission path.
(2) The temperature dependence of these two quantities is similar to the one reported previously!) forvibrations of 208Pb: they increase with T, to eventually reach a saturation around T ~ 4 MeV.
(3) This behavior is in agreement with findings
reported,2) at least qualitatively. Our damping rateis somewhat smaller, and its variation with the shapeis weaker than needed in the analysis of the ,-ray multiplicity encountered for fission of 224Th.2)(4) However, it must be said that we have not yet
striven for quantitative agreements. For instance,
there is room for a more appropriate choice of the twoparameters of collisional damping. In the present paper only their "standard choice" has been used, butthese values are open for changes within a certain*1*2

Condensed from the art icle in Nucl. Phys. A 616, 1 (1997)
Instit ute for Nuclear Research of the Ukrainian Academy of
Sciences , Russia
Physik-Depart ment der Technischen Universitat Miinchen ,Germany

margin,3) and such modifications will not only change
the values of the transport coefficients but also theirvariation with T.!) Furthermore, one should mention
the influence of pairing, which still might be important at a value of T smaller than 1 MeV, but which
we have left out for the sake of simplicity. Moreover,the influence of angular momentum ought to be taken
into account (see below).
It should be said, of course, that the numbers extracted from the comparisons with experiment aremodel dependent. Moreover, in simplified studies
Kramers' picture is often applied, even in the cases
where the barrier is too low to guarantee that the flux
across the barrier can be described by Kramers' solution of the Fokker-Planck equation. This problem canonly be cured by performing genuinely dynamical studies along the lines reported 4- 8 ) but where all ingredients into macroscopic descriptions with Fokker-Planck
or Langevin equations come from the same theory.
(5) Finally, we would like to come back to the angular momentum, once more, which influences fission
dynamics in a manyfold way. First of all, it changes
the quasi-static energy through the centrifugal potential. Generally, this reduces the height of the barrier
and thus restricts further the range of temperatures
for which Kramers' formula of the fission decay rate isapplicable. The centrifugal force will also modify the
local stiffness, which in turn affects the local response
in various ways. However, even in zero frequency limit
rotations will have a sizable impact on the transportcoefficients. This has been demonstrated in the caseof friction. 9 ) The reason for such a behavior is foundin the fact that in the rotating frame the level structure may become very different from the one without
rotations.
References
1) H. Hofmann et al.: Nuel. Phys. A 598, 187 (1996).
2) P. Paul and M. Thoennessen: Ann. Rev. Part. Nucl.
Sci. 44, 65 (1994) .
3) H. Hofmann: Phys. Rep. 284, 137 (1997) .
4) E. Strumberger et al.: Nucl. Phys. A 529, 522 (1991).
5) P. Frobrieh and I. I. Gontchar: Nucl. Phys. A 563, 326(1993).
6) T . Wada et al.: Phys. Rev. Lett. 70, 3538 (1993).
7) T. Wada et al. : 2nd RIKEN-INFN Joint Int . Conf. on
Heavy Ion Collisions, Wako, World Scientific, Singapore(1995).
8) K. Pomorski et al.: Nucl. Phys. A 605, 87 (1996).
9) K. Pomorski and H. Hofmann: Phys. Lett. B 263, 164(1991) .
31

RIKEN Accel. Prog. Rep. 31 (1998)

Collective Motion at Finite Excitations in
Terms of Cassini' Ovaloids t
F. A. Ivanyuk,*l H. Hofmann,*2 V. V. Pashkevich,*3 and S. Yamaji[Collective motion, Nuclear dissipation, Quasi-static thermodynamics]
Previous computations of the potential landscapewith the shapes parameterized in terms of Cassini
ovaloids 1 ,2) are extended to collective dynamics at finite excitations. Taking fission as the most demanding
example of large scale collective motion, transport coefficients are evaluated along a fission path. We concentrate on those for average motion, namely stiffness
C, friction 'Y and inertia M. Their expressions are formulated within a locally harmonic approximation on
the basis of the linear response theory. Different approximations are examined and comparisons are madeboth with a previous study,3) which involved different descriptions of single particle dynamics, as well aswith macroscopic models. Special attention is paid toan appropriate definition of the deformation of the nuclear density and its relation to that of the single particle potential. For the temperatures above 3 MeV the

*1

*2
.. 3

32

Condensed from the article in Phys. Rev. C 55, 1730 (1997)
Institute for Nuclear Research of the Ukrainian Academy of
Sciences, Russia
Physik-Department der Technischen Universitat Miinchen,
Germany
Joint Institute for Nuclear Research, Russia

inertia agrees with that of the irrotational flow to lessthan a factor of two, but shows larger deviations below
3 MeV, in particular in its dependence on the shape.
Also, friction exhibits large fluctuations along the fission path for small excitations. They are smoothed out
above 3-4 Me V where 'Y attains values in the range of
the wall formula. For T ~ 2 MeV the inverse relaxation time f3 = 'Y / M turns out to be rather insensitive
to the shape and increases with T.
References
1) V. S. Stavinsky, N. S. Rabotnov , and A. A. Seregin:
Yad. Fiz. 7, 1051 (1968).
2) V. V. Pashkevich: Nucl. Phys. A 169, 275 (1971).
3) S. Yamaji, F. A. Ivanyuk, and H. Hofmann: Nucl. Phys.
A 616, 1 (1997).

RIKEN Accel. Prog. Rep. 31 (1998)

Nucleus as a Canonical Ensemble:
The Inverse Laplace Transformation
H. Sato[NUCLEAR STRUCTURE w, E, and thermal properties of nuclei]
The nuclear level density is an important quantity to
extract nuclear thermodynamical quantities of highly
excited nuclear states formed by the nucleus-nucleus
collision. A conventional formula for the nuclear level
density is obtainable employing the saddle-point approximation in the inverse Laplace transformation of
micro canonical treatment of the free Fermi gas. If weemploy this approximation, we obtain an exp( .J2aE)
type dependence of level density for the excitation energy E.l) However, if the saddle-point method is not anadequate approximation for the inverse Laplace transformation of the nuclear system, the exp( .J2aE) typeenergy dependence may not work. In previous works,
we have studied the nuclear system at both low andhigh excitation energies in terms of the canonical ensemble, employing the temperature dependent antisymmetrized many particle density matrix in a harmonic oscillator (HO) potential with its trace: 2 )ZN({3) = ~shell model in the low temperature limit, and that thevarious phenomena observed in the intermediate andhigh energy nuclear collisions are nicely explainable as
the property of this ensemble at high temperatures.
In this work, we perform an exact calculation of theinverse Laplace transformation:

r

ioo

1
p(N, E) = 27ri } -ioo ZN({3) exp( +(3E)d{3,employing a computational program of the multiprecision arithmetics extended so as to include thecomplex functions needed in the calculation. The
multi-precision arithmetic calculation is based on themethod described elsewhere,3) and the calculation becomes feasible under the accessibility of 64 bit integers
in the computer. Then, we can study the validity of
the conventional formula for the nuclear level density
given by a saddle-point approximation.

NI) -It+ H nf3 Z N- n ({3) with Zo = l.
1

n=lHere, Hnf3 is the trace of one particle density matrix
having a temperature of n{3. We found that this ensemble is equivalent to the ground state of the HO

References
1) A. Bohr and B. R. Mottelson: Nuclear Structure, Vol.
1 (Benjamin, New York, 1969), p. 28l.
2) H. Sato: Phys. Rev. C 36, 785 (1987).
3) H. Sato: RlKEN Accel. Prog. Rep. 26, 31 (1993).

33

RIKEN Accel. Prog. Rep. 31 (1998)

Damping Width of the Mie Plasmon
H. Kurasawa,*l K. Yabana,*2 and T. Suzuki[Giant resonance states]
Giant resonance state is a fundamental collective
state of nuclei. It is characterized by the excitation
strength, mean excitation energy and width. The
strength is understood in terms of the classical energyweighted sum rules, while the mean energy is describedwith the random phase approximation. As a result, themass number dependence of the strength and mean energy is well understood theoretically. The width, on
the other hand, is estimated with various models, but
not studied in a systematic way so far. In order to finda way to investigate the systematics of the width, wehave applied Tomonaga theoryl ) to Mie Plasmon of themetal clusters. 2) Before discussing nuclear giant resonances, we have studied Mie plasmon, because Hamiltonian of the atomic clusters is rather well known.
The Hamiltonian of the electrons in an atomic cluster is given by
Ne
2
Ne Ni
H=~~-~~

Z 2

1 Ne

2

e
+_~
e
8~ Iri -Ral 2
Iri -rjl'

8 2m

t'

where N i and Ne denote the number of ions withcharge Ze and that of electrons , respectively. The Mie
plasmon is a dipole oscillation of electrons against ions,which is similar to nuclear dipole states. Hence, we introduce the collective variables for the Mie plasmon,

(1)

(7)
for the spherical electron density distribution, Pe (r).
If there is no spill-out of the electron density from thesurface of the ion distribution, the above equation is
reduced to the well-known Mie frequency of the classical electrodynamics. 3)
The width of the Mie plasmon is discussed with variance which is given by2)
1
(j =l(mIHi~lw)12 = -mw
2
l(mIHiIO)1 2 , (8)
m
m

L

L

where 1m) represents the state orthogonal to the collective state, Iw). Since
does not excite the collective
state, Iw), the sum over 1m) in (j can be replaced bythat over the complete set, In), which includes Iw).
Finally we obtain 2)Hi

4(j ';:::j

Ne
2:nw

J12

Pe (r ) dr ,where we have defined 1 = z (r- 3 - R - 3 ) ()(r - R).
The above equation shows that the width comes fromthe spill-out of the electron density from the surfaceof the ion distribution. If there is no quantum effect ,then we have (j = O. The ground state density of large
clusters is well described by the Fermi-type function 4 )as the nuclear density,noPe(r) = 1 + exp((r _ R _ 8R)/a) ,which satisfies the canonical relationship, [~, 7r] = i.
Then we can expand the Hamiltonian in terms of thecanonical variables according to Tomonaga theory,(2)
where Hi'S do not include ~ and 7r by the definition,andandare given by

Hi

Hg

Hi = i[7r, H] + ~[7r, [7r, H]] - 7r[~, [7r, H]] ,Hg = -[7r, [7r, H]] .

(3)

(4)

Assuming the ion distribution,

3Ni

(5)

Pi(r) = 47rR3 8(R - r) ,

R,

Hi

Hg

with the radius
we calculate
andexplicitly.
Then we obtain the frequency of the Mie plasmon,2)

_J

e2N

w-

eff

mR3'

(6)

where Neff is given by*1

Department of Physics, Faculty of Science, Chiba University*2 Department of Physics, Niigata University

34

(9)

(10)

where 8R expresses the difference between the electron
and ion distributions. Since both a and 8R are known
to be small compared with R , we expand Eq. (9) interms of a/Rand 8R/ R. Finally we have9a3(j(R -+ 00) = 2mw~ R ¢(8R/a) ,(11)

where ¢(8R/a) is a function which is independent of R.
The above equation shows that the width given by thesquare root of (j is proportional to 1/ JR. Since R is
known to be rv N1/3, we can obtain the Ne-dependenceof the width.
In conclusion, Tomonaga theory is useful to explore
the systematics of the width. Its application to discussions on the width of nuclear giant resonance states isin progress.
References
1) S. 1. Tomonaga: Prog. Theor. Phys. 13, 467 (1955); T.
Suzuki: J. de Phys. 45 , C4-251 (1984).
2) H. Kurasawa et al.: Phys. Rev. B 56, R10063 (1997).
3) G. F. Bertsch and R. A. Broglia: Oscillations in Finite
Quantum System (Cambridge Univ. Press, 1994).
4) N. D. Lang and W. Kohn: Phys. Rev. B 1, 4555 (1970).

RIKEN Accel. Prog. Rep. 31 (1998)

Explosion of a Neutron Star Just Below the Minimum Mass:
A Possible Site for r-Process Nucleosynthesis
K. Sumiyoshi, S. Yamada, H. Suzuki, and W. Hillebrandt*[r-process, neutron star, ,B-decay]
Neutron star explosion is extremely interesting since
it is connected with the origin of elements. Dense matter in neutron stars contains a plenty of free neutronsand seed elements, which can supply the conditions
for r-process nucleosynthesis. Therefore, the expansion of the neutron star matter may lead to a rapidneutron capture with ,B-decay, and may produce heavy
elements through r-process. However, prediction of theabundance of heavy elements in neutron star explosions has a large uncertainty, depending on the dynamics of expansion of the neutron star matter, since
the mechanism of the explosion is not known very wellyet.
We study the evolution of a neutron star with a mass
slightly below the minimum stable mass as a possible
scenario for the explosion of neutron star and for rprocess nucleosynthesis. Possibilities of the formationof a neutron star with the minimum mass have been
discussed in various contexts such as neutron star neutron star (or - black hole) binaries or fragmentationof a rotating core of massive stars.
It is known that the neutron star with the minimum
mass is unstable against perturbation if the neutronstar matter is in chemical equilibrium having enoughfast nuclear reaction rates. However, nuclear reactions
like ,B-decays of neutron-rich nuclei have a wide rangeof time scale, which depends on hydrodynamics andcan be much longer than the hydrodynamical timescale. Therefore, one has to treat both hydrodynamics
and nuclear reactions simultaneously in order to findout whether the star becomes unstable and explodes.
We have performed numerical simulations using a
new implicit hydrodynamic codel} with nuclear reactions to investigate: the dynamical instability of aneutron star just below the minimum mass, the thermal history of the matter, and its consequence on
nucleosynthesis. 2 ) General relativistic hydrodynamics
is solved with the nuclear processes treating ,B-decay,
neutron capture and fission of nuclei, which change theequation of state of the neutron star matter and provide the sources of heating and cooling.
We have followed the evolution of a neutron starwith the minimum mass after a small portion of themass is removed from the surface as an initial perturbation. We have found that such a neutron star firstundergoes a phase of quasi-static expansion, caused byslow ,B-decays, lasting for about 20 seconds, but thenexplodes violently within 0.1 seconds. (See Fig. 1) The
Max-Planck-Institut flier Astrophysik, Germany

10'

1
]"
10'

o.

1

'--'--'---'-----'---L--'---'---'---'----'--L-.J........I--'--'----'--'---'--~

21

21.2

21 .4

21.6

21.8

22

time [sec)Fig. 1. The trajectories of selected mass-zones of theneutron star are plotted as a function of time.
phenomena look like a "mini-supernova" event having
the kinetic energy of the order of 1049 erg and thepeak luminosity in electron anti-neutrinos of the orderof 1052 erg/so
The thermodynamic conditions of the expanding
matter are found favorable for the r-process nucleosynthesis with the peak temperature close to 5 x 109 K
due to ,B-decays and fissions. This temperature is highenough to proceed the nucleosynthesis having charged
particle nuclear reactions, but not high enough to reacha nuclear statistical equilibrium. The path of nucleosynthesis goes through neutron-rich side of the nuclear chart having a rapid neutron capture with ,Bdecays and fissions. Therefore, the nucleosynthesis
proceeds as a kind of r-process, and produces heavy
elements reflecting the initial composition in the neutron star matter. 2)
We are extending the investigation by adopting more
realistic equation of state of dense matter and ,B-decay
and fission of unstable nuclei, so that we can predict
the outcome of r-process nucleosynthesis more quantitatively and can compare with observational abundances.
References
1) S. Yamada: Astrophys. J. 475,' 720 (1997).
2) K. Sumiyoshi, S. Yamada, H. Suzuki, and W.
Hillebrandt: submitted to Astron. & Astrophys., astroph/9707230.
35

RIKEN Accel. Prog. Rep. 31 (1998)

Relativistic Equation of State for Supernova
H. Shen, K. Sumiyoshi, K. Oyamatsu, and H. Toki
[Equation of state, Relativistic mean field theory, Thomas-Fermi calculation]
The equation of state (EOS) is one of the most important inputs in the study of the supernova explosion and some other astrophysical processes. Therefore , great efforts have been made by several groups toderive the EOS covering a wide variety of conditions.
Lattimer and Swesty made the EOS for stellar collapse
calculations using the compressible liquid-drop modelfor nucleL l ) They used the parameterized form for thebulk energy of nuclear matter, and extrapolated it tohigh densities. Another approach to the EOS table
for supernova was done by Hillebrandt and Wolff. 2)
They applied the nonrelativistic Hartree-Fock theory
with the Skyrme interaction to extract the EOS covering a wide range of the density, proton fraction, andtemperature .
Recently, on the other hand, the relativistic manybody approach is gaining popularity. The relativistic
mean field (RMF) theory was demonstrated to be successful in describing the properties of both stable nuclei and unstable ones. 3 ) Hence, it is very important tostudy the properties of the EOS for supernova in the
RMF theory which is best supported by both the theoretical and experimental information currently available.
It is the primary aim of this paper to provide a relativistic EOS for simulation studies of the supernova
explosion, which is covering a wide range of the density(nB = 105 '" 10 15 .5 g/cm 3 ), proton fraction (Yp = 0 '"0.5), and temperature (T = 0 rv 50 MeV). The relativistic mean field theory with non-linear terms is usedin this calculation. We use the parameter set called
TM1,4) which was extracted from the properties of finite nuclei in the wide mass range in the periodic table
including neutron-rich nuclei. For the densities from
105 g/cm 3 to 10 14 g/cm 3 , the matter is inhomogeneous
as modeled by a mixture of electrons, muons, freeneutrons, free protons , and a single species of heavy
nuclei. In this case, we perform the Thomas-Fermi
calculations following the work done by Oyamatsu. 5)
At the density around 10 14 g/ cm 3 the phase transition between non-uniform matter and uniform mattermay occur. We follow the work done by Sumiyoshi etal. 6) in the uniform matter case. We are treating theuniform matter and non-uniform matter consistently.
So, all the thermodynamic quantities, like energy per
particle, pressure, chemical potential, and so on, arevery smooth in the whole region. It is amazing to
see that the density of phase transition between non-36

uniform matter and uniform matter depends on Yp
only weakly, while the density of neutrons drippingout from nuclei depends on Yp very strongly at zerotemperature (see Fig. 1). It will be very interesting
to see this kind of phase transition at finite temperature. This EOS has been applied to the studies of
the neutron star property and neutron star profiles.
We are currently working out relativistic EOS at finite
temperature.

n . ~ f-~n.4

Thomas-Fenni(without neutron gas)...... ------ .. ---- ..

/•••••Beta Equilibrium Curve " ' \RMF

0.. n..l~_ _ _ _ _ _ _~:~.--J

>n.2

/
.

Thomas-Fenni(with neutron gas)"n.o ............L..I.J..J~L.L.L.LJ....L.u...L..I.J..J~IL.L.L.LJ....L.u...LJI.............LJ.··u...·-.L.L-Lu...L~.J..J....uoj
8

III

12

LoglO(density) (glcm 3)

14

Fig. 1. The configurations of nuclear matter at zero temperature. The region denoted by RMF corresponds tothe uniform matter described by RMF theory. The
regions denoted by Thomas-Fermi (without and withneutron gas) correspond to the non-uniform matterwithout and with neutron gas, calculated with theThomas-Fermi model using the EOS of RMF. f3 equilibrium curve is also provided, which indicates Yp atvarious densities with f3 equilibrium condition.

References
1) J. M. Lat timer and F. D. Swesty: Nucl. Phys. A 535,
331 (1991).
2) W. Hillebrandt and R. G. Wolff: in NucleosynthesisChallenges and New Developments, edited by W.
D. Arnett and J. M. Truran (Univ. Chicago Press,
Chicago, 1985) , p. 131.
3) D. Hirata et al.: Nucl. Phys. A 616, 438c (1997).
4) Y. Sugahara and H. Toki: Nucl. Phys. A 579, 557(1994).
5) K. Oyamatsu: Nucl. Phys. A 561, 431 (1993).
6) K. Sumiyoshi, H. Kuwabara, and H. Toki: Nucl. Phys.
A 581, 725 (1995).

RIKEN Accel. Prog. Rep. 31 (1998)

Can the Equation of State of Asymmetric Nuclear Matter
Be Studied Using Unstable Nuclei?
K. Oyamatsu, I. Tanihata, Y. Sugahara, K. Sumiyoshi, and H. Toki
[Unstable nuclei, Equation of state, Atomic masses, Nuclear radii]
This paper shows that nuclear radii and neutron
skins do directly reflect the saturation density of asymmetric nuclear matter (Fig. 1). The proton distributions in a nucleus have been found to be remarkably independent of the equation of state (EOS) of the asymmetric matter. It is the neutron distributions that are
dependent on the EOS (Fig. 2).

0 .10 r---.--.,----.------.-~----,

<'J~

E

'=- 0 .06 t:--2:::.::::::::::::::=~~ 0 .04';;'"- -- - Sill
-TM1

0 .02

10

12

,(1m)

80 __ ,>.Ll..J.-· "'V':>E'=- 0 .06
".

~~

0 .04
0.02

80 __ ·JI·l'l.J.-r;u"ig
8~0.00 L--_.L.-_~__L_----L:::::....~_-.l

o
60

10

12

,(1m)

40

20

20

40

60

80

100

120

140

200

220

240

260

280

300

neutron number

Fig. 1. Central densities of nuclei obtained from macroscopic calculations in SIlI-EOS (upper figure) andTM1-EOS (lower figure) .

Macroscopic model calculations have been performed over the entire range of the nuclear chart basedon two popular phenomenological, but distinctively
different, EOS: the SIn parameter set for the nonrelativistic Skyrme Hartree-Fock theory and the TMIparameter set in the relativistic mean field theory. The
saturation density for a small proton fraction remains
almost the same as the normal nuclear matter density
for the SIn EOS, but it becomes significantly small for
the TMI EOS.
The key EOS parameters used to describe the saturation density are the density derivative of the symmetry energy and the incompressibility of symmetricFig. 2. Proton and neutron distributions in 208Pb
and 266Pb calculated with SIIl-EOS (dashed lines) andTM1-EOS (solid lines) . The winding curves depict theresults of microscopic calculations. Macroscopic calculations for the proton distributions in 266Pb are indistinguishable.

nuclear matter, while the saturation energy is written
using the symmetry energy alone as a good approximation.
We conclude that a systematic experimental studyof heavy unstable nuclei would enable us to determine
the EOS of asymmetric nuclear matter at around thenormal nuclear matter density with a fixed proton fraction down to approximately 0.3. Therefore, the answer
to the title is yes.
References
1) K. Oyamatsu, 1. Tanihata, Y. Sugahara, K. Sumiyoshi,
and H. Toki: to be published in Nucl. Phys. A .

37

RIKEN Accel. Prog. Rep. 31 (1998)

Exotic Nuclear Rod Formation Induced by Superfluid
Vortices in Neutron Star Crusts t
Y. S. Mochizuki, K. Oyamatsu, and T. Izuyama[Neutron stars, Pulsars, Dense nuclear matter, Screened Coulomb potential, Glitches]
The inner crust of a neutron star consists of a lattice of nuclei, relativistic degenerate electrons, and aneutron superfluid. Since the star is rotating, there
are a number of quantized vortices in the superfluid.
Mochizuki & Izuyama (1995) pointed out that suchvortex lines may induce nuclear matter rods along thevortex cores. The exotic nuclear structure is possible ina very limited region of the inner crust. However, theshort nuclear rod can completely pin the vortex line
and can be an origin of vortex accumulation. The accumulation goes on until the local Magnus force among
the accumulated vortices reaches a critical magnitude
for unpinning of the trapped vortices. The unpinningat this stage, which must be collective, leads to pulsar
glitches (sudden increases in rotation rates).
In this paper, we first reconsider energetics of this
vortex-induced nuclear matter rod given by Mochizuki
and Izuyama. 1 ) We present a view that the nuclear
rod is constructed by successive captures of certain
neighboring nuclei into the vortex core and subsequent
fusion reactions of the captured nuclei with those inside the vortex core. We found that the marginal region, where the induced nuclear rods are stable, is not

Condensed from the article in Astrophys. J. 489, 848 (1997)
38

trivial.
As the next step, the possibility of nuclear rod formation should be warranted by dynamical analysis .
The crucial part of the dynamics is the Coulomb potential barrier, which seems at first sight to prohibit
fusion if one neglects the screening due to electrons.
Then we report also our theoretical estimate of thisCoulomb barrier, i.e. , the energy increase when a nucleus deviates from its equilibrium site to the onset
position of nuclear fusion. The screening of nuclear
charge by the background electrons is accurately taken
into consideration. We found that the Coulomb barrier against the rod formation is of the order of 1 Me V
throughout the marginal region. The obtained barrier
is only several times as large as the zero-point energyof nuclei forming crystalline lattice. This result suggests that pycnonuclear reactions are feasible for therod formation.
References
1) Y. Mochizuki and T . Izuyama: Astrophys. J. 440, 263(1995).

RIKEN Accel. Prog. Rep. 31 (1998)

Dynamics of Exotic Nuclear Rod Formation
for Neutron Star Glitches t
Y. S. Mochizuki, T. Izuyama, and I. Tanihata[Neutron stars, Pulsars, Dense nuclear matter, Phycnonuclear fusion reaction, Glitches]
The inner crust of a neutron star comprises latticesof neutron rich nuclei and a neutron superfluid, inwhich many quantized vortex lines exist. The vortex
lines are pinned by nuclei but can jump from a pinningsite to another. In the previous papers by Mochizuki& Izuyama (1995)1) and by Mochizuki, Oyamatsu &Izuyama (1997),2) it was pointed out that such vortex
lines may induce nuclear matter rods along the vortex
cores. This exotic nuclear rod along a vortex line isformed by captures of nuclei from outside the vortex
core and by subsequent fusion reactions of the captured
nuclei with the nuclei inside the core.
The nuclear rod was shown to have a lower energy
than the original nuclear lattice. As the next step, dynamics for the rod formation is required. Namely, toconclude that the nuclear rods are actually formed in
the neutron star, we need to confirm that the formation time of the nuclear rod is shorter than the timeof the vortex sojourn at a pinning site. It is the purpose of this paper to confirm this. We find that, under certain plausible conditions appropriate to the Velapulsar, the rod formation time is indeed much shorter
than the vortex sojourn time in the frontier region (theregion where a vortex line is tangent to the central coreof the star). The rod formation is attained by pycnonuclear reactions rather than by thermonuclear ones. The
resulting exotic nuclear --rod formation in the frontier
region is crucial to understand the physical origin of
pulsar glitches (sudden increases in rotation rates) as
proposed by Mochizuki and Izuyama. 1 )References
1) Y. Mochizuki and T. Izuyama: Astrophys. J. 440, 263(1995).

2) Y. S. Mochizuki, K. Oyamatsu, and T. Izuyama: Astrophys. J. 489, 848 (1997).

Condensed from the article submitted for the publication in
Astrophys. J. (1997); RIKEN-AF-NP-266(preprint)

39

RIKEN Accel. Prog. Rep. 31 (1998)

High Ratio of 44Ti/ 56 Ni in Cas A and Axisymmetric
Collapse-Driven Supernova Explosiont
S. Nagataki,*l M. Hashimoto,*2 K. Sato,*l S. Yamada,*1,3 and Y. S. Mochizuki[44Ti half-life, Supernova, Cas A, SN 1987A, Nucleosynthesis]
Cassiopeia A (Cas A) is a young supernova remnant
which is located relatively close to us (2.9 ± 0.1 kpc).
There is an old record that John Flamsteed observed
this supernova phenomenon (ca.1680 AD) and the newstar had an apparent brightness of the 6th magnitude.
The mass of the progenitor is estimated to be (1530) times the mass of the sun M0, which implies that
Cas A is the remnant of a collapse-driven supernova
explosion.
Recently, Cas A was observed by the COMPTEL
telescope aboard the Compton Gamma-Ray Observatory, and the gamma-ray line (1.157 MeV) from
44Ti decay was detected at the significance level of40'. The measured line flux was (4.8 ± 0.9) x 10- 5
photons/cm 2/sec. The inferred amount of 44Ti islarger than 1 x 10- 4M 0 , although this estimate depends on the distance and the age of Cas A, and especially, on the half-life of 44Ti which is still very uncertain. The half-life of 44Ti has been reported to fall in
the range from 39 ± 4 yr to 66.6 ± 1.6 yr. This range
corresponds to (50-98) yr in terms of the lifetime.
The inferred initial mass of 44Ti, 1x10- 4 M 0 , islarger than the theoretical prediction 1) even if we
adopt the lower limit of the COMPTEL observation.
Moreover, this amount of 44Ti should be accompaniedby the ejection of at least 0.05 M 0 of 56Ni, if we assume
that the theoretical prediction 2) for the ratio of massfractions, X(44Ti)/X(56Ni) :S 1.89 x 10- 3, is correct.
However, this much 56Ni would have led to the peakabsolute brightness of magnitude-4, and would
have been much brighter than the recorded 6th magI"V

I"V

*1

*2

.. 3

40

Condensed from the article in Astrophys. J. 492, L45 (1998):
RIKEN-AF-NP-277 (preprint)
Department of Physics, School of Science, the University ofTokyo
Department of Physics , Faculty of Science, Kyusyu
University
Max-Planck-Institut fUr Physik und Astrophysik

nitude of the apparent brightness. This is the puzzlingabundance problem of Cas A.
It is noted here that the above constraint on
X(44Ti)/ X(56Ni) is obtained on the assumption thatthe explosion is spherically symmetric, whereas Cas
A is famous for the asymmetric form of the remnant.
Recently, Nagataki et al. (1997)3) calculated the explosive nucleosynthesis of an axisymmetrically deformed
collapse-driven supernova. They reported that the ratio of 44Ti/ 56 Ni was enhanced by the stronger alpharich freezeout in the polar region.
In present paper, we apply these results to Cas A
and examine whether this effect can explain the large
amount of 44Ti and the large ratio of 44Ti/ 56 Ni. We
demonstrate that the conventional spherically symmetric explosion model cannot explain the 44Ti mass produced in Cas A if its lifetime is shorter than 1"V80 years.
On the other hand, we show that the axisymmetric explosion models can solve the problem. We expect thesame effect from a three-dimensionally asymmetric explosion, since the stronger alpha-rich freezeout will also
occur in that case in the region where the larger energy
is deposited.
References
1) F. X. Timmes et al.: Astrophys. J. 464, 332 (1996).
2) S. E. Woosley and R. D. Hoffman: Astrophys. J. Lett.
368, L31 (1991).
3) S. Nagataki, M. Hashimoto, K. Sato, and S. Yamada:Astrophys. J. 486, 1026 (1997).

RIKEN Accel. Prog. Rep. 31 (1998)

Low Energy Aspects of the Field Strength Approach
T. Matsuki[Quantum chromodynamics, 1+1 dim, Field strength formalism, Confinement]
The field strength formalism l ) (FSF) of gauge theory has recently attracted attention. The non-Abeliancase was shown to exhibit gluon condensation, evenat the classical level. 2) Clearly, it would be favorable
if. cases were found where the FSF could be solved at
the full quantum level. Here, we analyze QCD I + I on a
spatial circle (space-time cylinder), where the solution
is known to give a non-trivial spectrum.
The FSF consists in introducing the auxiliary field
X which is conjugate to the field strength F:v' Naturally, X is an anti-symmetric tensor which transforms adjointly under local color rotations. Integrating over the gauge field A~ in the path integral gives
Z = J [DX] e - (L) in which
L = ~X2 -torus to S2. The integer is invariant against continuous deformations of the field ()(x). Thus, we have amanifestly gauge invariant form of Lagrangian for pureSU(2) on a cylinder.
.
We may equivalently start from the gauge fixed Lagrangian, and the F-P ghost term plays the role of
the Jacobian. The gauge which meets our requirements is evidently the Diagonal gauge 3 ) in terms of x,
since our method consists in diagonalizing the matrix
Xbe = Xacabe . The calculation is performed to giveZ =J

[DXDC3 ]II :26" (X a )a=I,2 ~FP (X) e- S[x,c31,
x~6"4 (0) Tr (lnx) - ~apX~p [X-IJ:~ a1JX~rl'be =- XJ.LVa jabe andt es the m. t egrah
were
XJ.LV
< ...d> eno
Dtion over space time (J d x).
Since there is only one Lorentz component XOI for
the case D = 2, the inverse of Xa jabe is ill defined.
Thus, people have refrained from using FSF in 1+1
dimensions. Nevertheless, one has only to integrate
over the non-singular directions of X, which means that
diagonalization of X is necessary. As a result, we findA

Obvious notations are Xa == Xch, p == JXaX a and C a ==ptab A b, where P is the unitary matrix required for
diagonalization.
One observes a complicated kinetic term and a singular In p term in the Lagrangian. Importance of thesingular term has been emphasized in,2) since it renders gluon condensation at the classical level. It requires a non-perturbative treatment, since it cannot
be expanded in polynomial form.
In the case of QCD I +I we can take care of both difficulties by considering a point transformation whose
Jacobian explicitly cancels the singular term. This isseen by writing for the SU(2) casex

where {Xl, X2, X3 }={p sin () cos c.p, p sin () sin c.p, p cos ()}.
The p2 term arising from the Jacobian is exactly what
is required to cancel the singular term.
The kinetic term is a topological invariant which isan integer defined by the degree of mapping from thewhich is just QED for the U(l) subgroup of SU(2).
In order to obtain the spectrum, one has only to calculate the partition function for time-periodic gauge
fields, but with gauge equivalent fields identified. The
configurations that are equivalent modulo large gaugetransformations have nontrivial consequences on the
spectrum. Careful evaluation of the boundary condition gives

which renders En = ~g2 Ln 2 in agreement with previous analysis. 4 ) The result can be extended straightforwardly to SU(N) for an arbitrary N.
We have also calculated the ground state energy inthe presence of static sources in a separate work. Half
integer charges showed confinement, whereas integer
charges were screened at the distance where the total
loop around the torus became lower in energy than thestatic potential between the charges. This confirms the
charge screening scenario of adjoint charges. S )Thus we have presented an example where QCD issolved non-perturbatively, using the FSF. We have elucidated the problems which arise when one tries tosolve the problem quantum mechanically.
References
1) M. B. Halpern: Phys. Rev. D 16, 1798 (1977).
2) M. Schaden et al.: Nucl. Phys. B 339, 595 (1990).
3) G. 'tHooft: Nucl. Phys. B 190, 455 (1981).
4) J. E. Hetrick et al.: Phys. Lett. B 230, 88 (1989).
5) A. M. Polyakov: Gauge Fields and Strings (Harwood
Academic, 1987).
41

RIKEN Accel. Prog. Rep. 31 (1998)

Nuclear Transparency in a Relativistic Harmonic
Oscillator Quark Morlel t
T. Iwama, A. Kohama, and K. Yazaki[Color transparency, Relativistic quark model]
We examine the nuclear transparency in the quasielastic (e, e' p) process at large momentum transfer ina relativistic harmonic oscillator model 1) to take theinternal dynamics of the struck proton into account.
A proton in a nuclear target is struck by the incident
electron and then propagates through the residual nucleus suffering from soft interactions with other nucleons. We call the proton "dynamical" when we take
into account of internal excitations, and "inert" when
we freeze it to the ground state.
When the dynamical proton is struck with a hard(large-momentum transfer) interaction, it shrinks, i.e.,
small-sized configuration dominates the process. It
then travels through nuclear medium as a timedependent mixture of intrinsic excited states, and thus
travels changing its size,2) suffering from the absorption due to the soft interactions with nuclear medium
which depends on the transverse-size of the proton.
Since the nuclear transparency is a measure of the absorption strength, we calculate it in our model for the
dynamical case. The results are compared with thosefor the inert case.
We compare our results also with the experimental
data to examine the target-mass-number (A) dependence (Fig. 1). The effect of the internal dynamics
is observed, i. e., the transparencies of the dynamical
proton are enhanced from that of the inert proton if acorrelation parameter, ZI, has a finite value, which is inaccord with the idea of the color transparency. Thisphenomena, the color transparency, was predicted by
Brodsky and Mueller in the early 80's as a candidateof observing the effects of internal dynamics of proton
in high-energy nuclear reactions. 3)
We also find that the A-dependence will reveal thecolor-transparency effect more clearly. Based on amodel-independent discussion the transparency of theinert proton approaches to A -1/3 line for large A.
Therefore, deviations from the A -1/3-lines in the largeA regime could be a signature of the color transparency.

Condensed from the article in Nucl. Phys. A 621, 620(1997)

42

1. 0 .----.--.-.-"-,-rrr--.,--r-,.....,...,.,,,,...--,---,--T""T"""TT1..,-,
0 .9
Q2 = 6.77 [(GeV/ c)2]0 .8
(e. e'p)' ;::. . . . .
0 .7
"',

. =--- '~0 .6,,-' ,,-,
"-'
"-'

0.5

0 .4
0.3

v = 0 .02
- - - v = 0.05
. v = 0.25

0.2

. Inert Proton

Mass Number A

Fig. 1. Comparison of the nuclear transparency with experimental data of 12C, 56Fe, and 197 Au 4 ) as a functionof the mass number of the target, A. Q2 (= _q2) = 6.77[(GeV jC)2], where q is the 4-momentum transfer . The
dotted curve is the case of the inert proton. The solid,
dashed, and dot-dashed curves are the cases of the dynamical proton with v = 0.02, 0.05, and 0.25, respectively. Here, v is a parameter to specify the longitudinal-transverse dynamical correlation between quarks inthe struck proton. This correlation excites the transverse mode of the struck proton. The larger the valueof v becomes, the stronger the correlation becomes.

The hadronic process, such as (p, 2p), will show us
other aspects of the color transparency. We will leave
it for our future work.
References
1) K. Fujimura, T. Kobayashi, and M. Namiki: Prog.
Theor. Phys. 43, 73 (1970).
2) K. Yazaki, T. Iwama, and A. Kohama: J. Korean Phys.
Soc., Suppl. 29, S388 (1996).
3) S. J. Brodsky and A. H. Mueller: Phys. Lett. B 206,685 (1988).
4) T. G. O'Neill et al.: Phys. Lett. B 351, 87 (1995).

RIKEN Accel. Prog. Rep. 31 (1998)

Quark Distributions in the Nucleon by the Semi-Inclusive
Reaction on the Proton- and 3Be-Target
H. Kitagawa and Y. Sakemi*[Semi-inclusive reaction, Quark distribution]
Semi-inclusive reaction, in which the scattered lepton and produced hadron are detected simultaneously,
provides many kinds of information on the target depending on the tagged hadron, and is expected to givea unified view on the distributions of gluons and of sea
quarks. By this reaction the quark and gluon distributions are being investigated with polarized positron
beam and polarized gas targets (helium-3 eHe) andhydrogen) tagging pion and neutral kaon at Deutsches
Elektronen-SYnchrotron (DESY).
The semi-inclusive cross section for production of a
hadron, h, is given by

0 .8
en

0.6

....
S

0 .4

Q)
.~
Q)

~

en

0.0
0.6
en

Q)

·c
....
Q)

dCTh( Z, X, Q2) _ Lf e}qf(x, Q2)DJ(z)CTtotaldz
Lf e}qf(x, Q2)
1

We relate the spin asymmetry, A~arget' with the quark
spin distributions in the nucleon by using the quark
parton model for the 3He-target. The 3He can be regarded as a state of purely (lS 1 / 2 )3 configuration: i.e.,
3Het = Pt + P..!- + nt· We also assume the isospin
symmetry between the proton and the neutron. We
predict the spin asymmetries, A; and A~He ' using
the existing parametrizations for the quark distributions: CTEQ3L 1 ) for the unpolarized quarks q(x), andGehrman-Stirling A(LO )2 ) for the polarized quarks
6.q(x). For the fragmentation functions D(z), we use
the recent parametrization3 ) for the charged pions andKaons . Due to the experimental layout, the range ofthe kinematical variable, z , is limited. We integrate thefragmentation function from Zmin to 1, where Zmin is
0.1. When both pions and kaons are tagged, expected
events areN;..!-~t~ = 2.: f ,nucleon e}qj(x)(DJ(z) +Df (z)).

Results of calculations are shown in Fig. 1 for thecases of the proton and 3He targets tagging positively charged hadrons (71"+ + K+), negatively charged
hadrons (71"- + K-), the sum of them (71"+ + 71"- + K+ +K-) and the difference of them (71"+ - 71"- + K+ - K - ).
Absolute values of the spin asymmetries of the case of
3He target are smaller than those of the proton-target
case. Asymmetries including kaons are not so different
from those of only pions. This may be because thefragmentation functions for kaons are not so different
from those of pions. These asymmetries are sensitive
to the value of the lower limit of z.

0.2

ro

S
S
:>,
en

0.4
0 .2

0.0

ro

-0.2
0.01

0 .05 0.1

0.5

1

x

Fig. 1. Spin asymmetries in which target is proton (upper)and 3He (lower) tagging pions and kaons are shown.
Lower limit of the kinematical variable z is 0.1.

For the precise prediction, we must know more about
the fragmentation function, to which the above asymmetries are sensitive. In the experimental side, it isdesired to have data at each z-bin, and the data of
the other nuclear targets are desired. In the theoretical side, quantitative estimations of the fragmentation
functions especially of pions are necessary. The lowest
moment fOl D(z)dz is not sufficient for the quantitative estimation, since the D(z) is singular at z = O.
We also should discuss a relation of the fragmentation
functions with the Lund model. It will be desirable toconsider the case of tagging short-lived neutral kaons
in order to investigate the unpolarized and polarized
strange quark distributions. 4)
References
1) H. L. Lai et al.: Phys. Rev. D 51, 4763 (1995).
2) T. Gehrmann and W. J. Stirling: Phys. Rev. D 53, 6100
(1996).
3) J. Binnewies, B. A. Kniehl, and G. Kramer: Z. Phys. C
65, 471 (1995).
4) H. Kitagawa and Y . Sakemi: R1KEN Accel. Prog. Rep.
30, 31 (1997).

Faculty of Science, Tokyo Institute of Technology

43

RIKEN Accel. Prog. Rep. 31 (1998)

Parameterization of the Polarized Parton Distribution Functions
Y. Goto, N. Hayashi, M. Hirai, .. l H. Horikawa, .. 2 S. Kumano, M. Miyama, .. l
T. Morii, N. Saito, T.-A. Shibata, E. Taniguchi, and T. Yamanishi[Polarization, Structure functions, Spin structure, Nucleon]
Polarized structure functions, gl (x), are now available for protons, neutrons and deuterons over a wide
range of the Bjorken x and squared momentum transfer Q2 from lepton to nucleon with a high precision,
due to the experiments of polarized lepton scatterings
off polarized nucleon targets. Data of the first momentof structure functions have indicated that the spin of
a nucleon is little carried by the quarks, and moreoverthe sea-quarks have negative polarization. In order toobtain a good knowledge of the nucleon spin structure, it is necessary to decompose the polarized structure functions into each flavor. So far, several kinds ofparametrizations on the polarized parton distributionfunctions (pPDFs)1-3) have been proposed. Recently,
however, it has been reported that the value of SMC
data at the lowest x dramatically decreased. 4 ) This
prompted us to re-analyze the pPDFs.
Our purpose here is to make a new parametrizationof the pPDFs for quarks and gluons having a high reliability at the leading order of QCD. We start with thefollowing parametrization of the pPDF at the initial
Q6 = 1 Gey2:

f:lh(x,Q6) = 1]iAixQi(l- x)(3ifi(X,Q6) ,(1)

where i represents the valence quarks U v and d v , seaquark q and gluon g, and fi(X, Q6) is the unpolarized
parton distribution function. The value of 1]i means
the amount of the parton i carrying the nucleon spinwith the normalization factor Ai. In Eq. (1), we assume a power-law behavior for the x dependence, x Qi ,for small-x regions, and a counting rule, (1 - X )(3i ,for large-x regions. Since the deep inelastic scattering (DIS) alone provides no sufficient information on
the behavior of the sea flavor, we simply assume theSU(3) flavor symmetry f:lu(x) = f:ld(x) = f:ls(x) at
the initial Q6.
By using the observed values of the neutron and hy-

.. I
.. 2

44

Department of Physics, Saga University
Faculty of Human Development, Kobe University

peron ,O-decay as follows,1]u v - 1]d v = F + D = 1.2573 ± 0.0028 ,1]u v + 1]d v = 3F - D = 0.579 ± 0.025 ,

(2)
(3)

we can obtain 1]u v = 0.918 and 1]d v = -0.339. Both 1]g
and 1]q remain as a free parameter because DIS cannot probe the gluon and cannot separate the contributions of the quark and anti-quark. The remaining
ten parameters are determined by fitting the experimental data on polarized DISs of the proton, neutronand deuteron for Q2 ;::: 1 Ge y2. For the purpose to
obtain a good parametrization, we follow the two step
analysis. First step: by using the reliable equation,1

gf(x) - g~(x) = (3 {f:luv(x) - f:ldv(x)} ,(4)

we roughly constrain the range of Qu v ' Qd v ' 'ou v and'od v ' Then, we use the combined data on gf, gf and g~ .
Second step: we determine the values of all parametersfrom the best fitting to all existing data. In practice,
we take the GRY95 parametrization as a typical unpolarized PDF.5)
The analysis is currently in progress.
We are indebted to Prof. T. Hatsuda, Dr. H.
Kitagawa, and Dr. Y. Watanabe for useful discussions.
References
1) S. J. Brodsky, M. Burkardt, and 1. Schmidt: Nucl. Phys.
B 441, 197 (1995).
2) M. Gluck, E. Reya, M. Stratmann, and W. Vogelsang:
Phys. Rev. D 53, 4775 (1996).
3) T. Gehrmann and W. J. Stirling: Phys. Rev. D 53, 6100
(1996).
4) B. Adeva et al., Spin Muon Collaboration: preprint
CERN-PPE/97-118.
5) M. Gluck, E. Reya, and A. Vogt: Z. Phys. C 67, 433(1995).

RIKEN Accel. Prog. Rep. 31 (1998)

Q2 Evolution of Polarized Parton Distributions
M. Hirai, S. Kumano, and M. Miyama*[Q2 evolution, Stucture function]
We have been working for obtaining the optimum
polarized parton distributions by analyzing existing
experimental data. l ) This collaboration consists ofthree subgroups: data analysis, parametrization, andQ2 evolution. We belong to the third group, which
contributes to the Q2 evolution program. The evolution equations are coupled integrodifferential equations with complex splitting functions in the next-toleading order (NLO). This subgroup tries to develop
an efficient program for numerical solution of the evolution equations. Here, we report on its Q2 evolution
studies. 2)
In solving the integrodifferential equations, we divide the variables x and Q2 into small steps and calculate the differentiation and integration by a brute-force
method. The same Gehrmann-Stirling (GS) set-A polarized parton distributions 3 ) are used as the input
distributions at Q2 = 4 Ge V 2 in both LO and NLO
cases. Our evolution results are compared with spinasymmetry data. The asymmetry Al is given by the
structure functions gi and FI as

A ~ gl(X,Q2) _ ( Q2) 2x (1 + R)
I - FI (x, Q2) - gi x,
F 2(x, Q2)(1)

where the function R is given by R
(F2 2xFI )/(2xF1 ). In Fig. 1, our evolution curves at
x = 0.25 are shown with the Al data by the SLACE130, SLAC-E143, EMC, and SMC. The unpolarized
MRS-G distributions are used for calculating the F2
structure function. The dashed and solid curves indicate the LO and NLO evolution results, respectively.
In the large Q2 region, both results are almost thesame; however, they differ significantly at small Q2
particularly in the region Q2 < 1 GeV 2. It indicatesthat perturbative QCD could not be applied in thesmall x region. From the figure, we find that the asymmetry has Q2 dependence although it is not large. People used to assume that the asymmetry is independentof Q2 by neglecting the Q2 evolution difference between gi and FI in analyzing the experimental data.
We found clearly that it is not the case. For a precise_ - - - - - - - -t- - - --t -----$- - - - - - - --

t

f'
~

0.1

- -

LO

-

NLO
•

x=O.25E143o

SMC (x=0.241)

o

EMC (x=0.248)

fl

E130

0.Q1+-~~~~~~~~~~'---",,-~~~

0.1

10

100

Fig. 1. Q2 dependence of the spin asymmetry Al iscalculated for the proton in the LO and NLO cases.
Calculated results at x = 0.25 are compared with the
SLAC-E130, SLAC-143, EMC, and SMC experimental
data.

analysis, the Q2 dependence of the asymmetry has tobe taken into account.
We have investigated the numerical solution of the
DGLAP Q2 evolution equations for longitudinally polarized structure functions. A FORTRAN program isprovided for the Q2 evolution and devolution of polarized nonsinglet-quark, singlet-quark, ~qi + ~iji' andgluon distributions (and corresponding structure functions). It will be used for obtaining the optimum
polarized parton distributions in the parametrization
studies. I)
References
1) RHIC-SPIN-J parametrization group: Y. Goto, N.
Hayashi, M. Hirai, H. Horikawa S. Kumano, M.
Miyama, T. Morii, N. Saito, T.-A. Shibata, E.
Taniguchi, and T. Yamanishi, research in progress.
2) M. Hirai, S. Kumano, and M. Miyama: Comput. Phys.
Commun. 108,38 (1998). Study of an efficient program
for the parametrization is still in progress.
3) T. Gehrmann and W. J. Stirling: Phys. Rev. D 53, 6100
(1996).

http://www.cc.saga-u.ac.jp/saga-u/riko/physics/
quantuml/structure.html.

45

RIKEN Accel. Prog. Rep. 31 (1998)

NLO Q2-Evolution of the Nucleon's Transversity
Distribution h 1(x, Q2)
A. Hayashigaki, Y. Kanazawa, and Y. Koike[Transversity, Twist-2, Anomalous dimension]
We present a calculation of the two-loop anomalous
dimension for the transversity distribution hI (x, Q2)
where x is the parton's momentum fraction and Q2 isthe scale at which hI is measured. It turns out that the
next-to-Ieading order (NLO) Q2- evolution of hI is very
different from that of the other twist-2 distributions,!I and gl, in particular in the small x-region.
hI (x, Q2) is the third and final twist-2 quark distribution function of nucleon. Because of its chiralodd nature, hI can not be measured in the totally inclusive deep inelastic scattering (DIS), but it appears
as a leading contribution in the transversely polarized nucleon-nucleon Drell-Yan process, and the semiinclusive DIS which detects pions, A's, or correlated
two pions in the final states. 1 ,2)Since hI is twist-2, its Q2 evolution is described by the Dokshitzer-Gribov-Lipatov-AltarelliParisi (DGLAP) equation. The leading order splitting
function for hI has been known for a quite some time. 2 )In the recent literature, three papers 3- 5 ) discussed the
NLO Q2 evolution of hI: Vogelsang 3 ) carried out alight-cone gauge calculation of the two-loop splitting
function for hI and converted it into the anomalous
dimension. We have carried out a Feynman gauge calculation of the two-loop anomalous dimension. 4 ) The
final results of these two calculations based on different
formalisms have agreed with each other. The result46

was subsequently confirmed by Ref. 5 in the same formalism as Ref. 4.
It turns out that ,~(1) (coefficient of the two loop
anomalous dimension for hI) is significantly larger
than ,~,9(1) (coefficient of the nonsinglet anomalous
dimension for !I and gd at small n, but approaches
very quickly to ,~,9(1) at large n, keeping the condition J~(I) > ,~' 9(1). This NLO effect in the anomalous dimension leads to a drastic difference in the Q2_
evolution between hI and gl in the small x region .. To
confront with future experiments, we have to combine
the NLO parton distribution function with a relevant
NLO short distance cross section in the same factorization scheme.
References
1) J. P. Ralston and D. E. Soper: Nucl. Phys. B 152; R.
L. Jaffe and X. Ji: Phys. Rev. Lett. 67, 552 (1991); R.
L. Jaffe and X. Ji: Phys. Rev . Lett. 71, 2547 (1993); R.
L. Jaffe, X. Jin, and J. Tang: hep-ph/9709322.
2) X. Artru and M. Mekhfi: Z. Phys. C 45, 669 (1990);
Nucl. Phys. A 532, 351c (1991) .
3) W. Vogelsang: Phys. Rev. D 51, 1886 (1998).
4) A. Hayashigaki, Y. Kanazawa, and Y. Koike: Phys.
Rev. D 56, 7350 (1997).
5) S. Kumano and M. Miyama: Phys. Rev. D 56, R2504(1997).

RIKEN Accel. Prog. Rep. 31 (1998)

The 1/;' Production in Polarized pp Collisions as a Test ofColor-Octet Mechanism
T. Yamanishi, T. Morii, D. Roy,*l K. Sudoh,*2 Z. Sun, and S. Tanaka*3[Charmonium, 'l/J' anomaly, Color-octet model, Spin structure]
Recently the CDF collaboration 1 ) has reported thatthe cross sections of prompt J /'l/J and 'l/J' productions in unpolarized pp collisions are largely inconsistent with the calculation by the quantum chromodynamics (QCD) lowest order process with the colorsinglet mechanism (CSM), and aroused renewed interest in heavy quarkonium productions. The longstudied CSM is essentially a nonrelativistic model,2) inwhich one cannot quantitatively estimate various uncertainties such as: the higher order QCD corrections;the quarkonium binding effects; and the corrections
due to relativistic effects of the quarkonium, which aresometimes treated as the "K-factor". The CDF result
suggests the necessity of other mechanisms in addition
to the CSM.
In these years, a new model called color-octet mechanism (COM), has been advocated by several people 3)
as one of the most promising candidates that could remove such a big discrepancy between the experimental
data and the prediction of CSM. The model is quite
successful in explaining the CDF data for large-P T
heavy quarkonium productions. However, the prediction of the COM on ,+ P -+ J /'l/J + X is inconsistent
with recent data at HERA,4) and thus the discussion
seems still controversial. To go beyond the present theoretical understandings, it is necessary to study otherprocesses.
In this report, as another test of the COM, we propose a different process, the 'l/J' -hadroproduction at
small-PT regions in longitudinally polarized PP collisions, which will be observed in the forthcoming RHIC
experiment. The process is of great advantage toclearly test the COM as described in the following.
Since the process is dominated by the s-channel gluongluon fusion, there is no direct productions of the colorsinglet 'IjJ' because of the charge conjugation. Only
two mechanisms contribute this process: the COM
and the 23P2 production. Using the three typicalpolarized gluon distributions: (a) set A (LO) of GS
parametrization,5) (b) the BBS parametrization,6) and(c) "standard" scenario GRSV parametrization,7) wehave calculated the double spin aymmetry ALL whichis positive for the COM and negative for the 23P2 production. As shown in Fig. 1, we have found that the

*1

*2

*3

sum of both contributions becomes inevitably positive
if the COM really contributes to this process. Furthermore, since the cross section of this process is directly
proportional to the product of Llg(x) in both protons ,the process is very useful to test the behavior of Llg(x).

'.5
At.(Pp) 0.4
0.3
0.2

0.1

0.2

0.4

t.6

1.1

Fig. 1. The two-spin asymmetry A t~ (pp) at ..;s = 50 Ge V
(lowest ..;s for RHIC) , calculated with various typesof t:1g(x) , as a function of the longitudinal momentum
fraction XL of 'I/J'. The solid, dashed and dotted lines
denote the set A of Ref. 5, 6, and 7, respectively.

References
1) G. A. Schuler: "Quarkonium production and decays",
CERN-TH- 7170- 94.
2) F. Abe et al.: Phys. Rev. Lett. 69, 3704 (1993); Phys.
Rev. Lett. 71, 2537 (1993).
3) E. Braaten and T. C. Yuan: Phys. Rev. Lett. 71, 1673
(1993); G. T. Bodwin, E. Braaten, and G. P. Lepage:
Phys. Rev. D 51, 1125 (1995); P. Cho and A. K.
Leibovich: Phys. Rev. D 53, 150 (1996); W.-K. Tangand M. Vanttinen: Phys. Rev. D 53, 4851 (1996).
4) M. Cacciari and M. Kramer: Phys. Rev. Lett. 76, 4128
(1996).
5) T. Gehrmann and W. J. Stirling: Phys. Rev. D 53, 6100
(1996).
6) S. J. Brodsky, M. Burkardt, and 1. Schmidt: Nucl. Phys.
B 441, 197 (1995).
7) M. Gluck, E. Reya, M. Stratmann, and W. Vogelsang:
Phys. Rev. D 53, 4775 (1996).

Faculty of Human Development, Kobe University
Department of Education, Kobe University
Department of Physics, Hyogo University of Education

47

RIKEN Accel. Prog. Rep. 31 (1998)

Heavy Quark Physics with Spin
T. Morii[Charmonium, Spin structure, Color-octet model]
Physics of the heavy quarks like charm and bottom
quarks is an important laboratory of testing both perturbative and nonperturbative Quantum Chromodynamics (QCD). Although the QCD, which is an underlying field theory of strong interactions of quarks
and gluons, is very successful in describing physics for
perturbative regions, it is not served well for nonperturbative regions. It cannot be directly applied for thelight quark hadrons at low energy where the systemis essentially nonperturbative. To deal with such asystem, people have to rely on some effective theories
such as: the chiral perturbation theory, the Skyrmion
model, the Bag model, and so on. On the other hand,
we do not need to worry about the nonperturbative
effect on the top quark system since the top quark is
extremely heavy and hence immediately decays into
a bottom quark emitting a W boson as a real process, and there is no chance to make a top hadron or
topponium. However, the charm and bottom quarks
which we call hereafter heavy flavored quarks are in
between these two limit of quark masses, and knowledge of both perturbative and nonperturbative QCD
is necessary. The potential model is still effective inthese systems together with the heavy quark effective
theory (HQET).l)
Recently, there have been new interests in physics ofthe heavy flavored quarks: how they work effectively
in extracting the information on the spin structure of
nucleons, and how they are produced in high energy
collisions. In the present report, we concentrate on
the following two topics which we have studied recently
and are related to these subjects above.
The first topic is on the extraction of the polarized
gluon distribution, t:lg(x), in the nucleon. Study of thegluon polarization in the nucleon which is still poorly
known is very important in order to solve the so-called
spin puzzle. 2 ) So far many processes are proposed to
examine various models of t:lg(x). Here we propose a
different process, + p -+ At + X, which might beobserved in the forthcoming COMPASS experiment. 3 )This process is expected to be effective for testingt:lg (x) since its cross section is directly proportional
to t:lg(x). In addition, the spin of At is carriedby the charm quark and thus measurement of polarization of At in the target fragmentation region
could determine the gluon polarization, t:lg(x). We
have calculated the two-spin asymmetry for this process and found that the process would be promisinge48

to test various models of polarized gluons.
The second topic is on a test of the color-octet
model of heavy quarkonium productions. Recently, the
CDP collaboration has observed prompt productionsof charmonium at Tevatron which were too large compared to the conventional QCD calculations. 4 ) This
dramatic discrepancy might make a new step toward
the deep understandings of the heavy quarkonium prod uction mechanism. One interesting and promisingmodel is the color-octet model. 5 ) To test this model, we
propose here an interesting process, p+ p -+ 'ljJ' + X, at
small PT regions. 6 ) Since this process is dominated by
the gluon-gluon fusion, there is no direct productionof color-singlet 'ljJ'. There are only two states which
are expected to contribute to the 'ljJ' production in the
final states: the color-octet state decaying to 'ljJ' + gand the 23 P2 state decaying to 'ljJ' + r. By using various models of t:lg(x) , we have calculated the two-spin
asymmetry, ALL, for these processes, and found that
it is positive for the color-octet state and negative forthe 23 P2 state. Furthermore, the sum of both contributions becomes positive for the present parameterregions, in particular, at y's = 50 GeV. Hence, if we
observe a positive ALL in the future RHIC experiment,
we can definitely tell that the color-octet model reallycontribute to this process. The process is therefore
very effective to test the color-octet model.
While much of experimental and theoretical progresshas been done thus far for the spin physics and heavy
quark productions together with the spectroscopy ofheavy flavored hadrons, the heavy quark physics is astill challenging subject which needs further investigation.
References
1) T. Matsuki and T. Morii: Phys. Rev. D 56,5646 (1997).
2) H.-Y. Cheng: hep-ph/9607254 (1996).
3) N.1. Kochelev, T. Morii, and T. Yamanishi: Phys. Lett.
B 405, 168 (1997).
4) F. Abe et al.: Phys. Rev. Lett. 69, 3704 (1992); Phys.
Rev. Lett. 71, 2537 (1993).
5) E. Braaten and T. C. Yuan: Phys. Rev. Lett. 71, 1673
(1993); G. T. Bodwin, E. Braaten, and G. P. Lepage:
Phys. Rev. D 51, 1125 (1995); P. Cho and A. K.
Leibovich: Phys. Rev. D 53, 150 (1996); W.-K. Tangand M. Vanttinen: Phys. Rev. D 53, 4851 (1996).
6) T. Morii, D. Roy, A. Sudoh, Z. -x. Sun, S. Tanaka, andT. Yamanishi: hep-ph/9708415 (1997).

RIKEN Accel. Prog. Rep. 31 (1998)

Measurement of a-Sticking Probability in Muon Catalyzed dt
Fusion by X-ray Method at RIKEN-RAL Muon Facility
K. Ishida, K. Nagamine, T. Matsuzaki, S. N. Nakamura, N. Kawamura, S. Sakamoto, M. Tanase,
M. Kato , K. Kurosawa, M. Hashimoto, K. Kudo,*l N. Takeda,*l and G. H. Eaton*2[Muon catalyzed fusion, Muonic X-ray]
The muon to alpha sticking probability Ws is one of
the most important observables in muon catalyzed dt
fusion, since it gives the upper limit on the numberof fusions that one muon can catalyze. The Ws has
been usually determined from the muon loss probability W per cycle measured by the time distributionof fusion neutrons, and has always shown smaller values than theoretical calculations. The measurement ofmuonic Ka X-rays from the recoiling (/.La) + ions provides an independent method,l) which more directly
measures the product that is related to the (p,a)+ ion
itself. At the RIKEN-RAL Muon Facility,2) muons
were stopped in the target of solid or liquid D-T mixture of various tritium concentrations, Ct. For eachtarget condition, a clear Ka peak was observed at 8.2
ke V with the help of the strong pulsed muon beam
above the bremsstrahlung background coming from tritium decay.3 ,4)The muon loss per cycle W can be determinedby combining the neutron yield Y n (per muon) andthe neutron disappearance rate An as W = (lAo/ An)yn- l , where AO is the free muon decay rate. In
Fig. 1 shown is the muon loss W obtained in our neutron measurement 5 ) for solid D-T mixture. Similar
C t dependence was observed for liquid data also. It isconsidered that the main component of W is the muon
to alpha sticking in dt fusion while the increase of W
at low C t is from muon sticking to 3He through dd fusion, and that at high C t is from muon to alpha sticking
through tt fusion. The muon transfer to 3He, which accumulates as tritium decays, was controlled with theuse of the advanced tritium gas handling system within situ 3He removal capability,6) and the data in Fig. 1
are already extrapolated to 3He free limit. By subtracting contributions of dd and tt processes the W s in
dt fusion was obtained to be around 0.45%, and seems
to be consistent with the previous measurements forliquid at PSI and LAMPF.
The number of Ka X-ray yield per fusion (Y(Ka))
was obtained as a funct ion of tritium concentration as
in Fig. 1. There has been several calculations on thenumber of X-rays emitt ed from (p,a)+ recoil ions , andthe obtained Y (K a ) can be converted to the sticking
probability by using t he result of those calculations.

•1

.2

E

1.0

I

I

I

I

c::

>. . VJ
~

....,

;.:::

~

*W

0 .8 r--:or.:r..
l1l

s...

0

0..

.D

s...

Q)

0 .6 r--X:z:

0.. '0

%
X

rn Q)
VJ

0
....:I>=X

c:: s...
I~::::s ><-

X-

0.4 r--

>.

l1l

¢

0

-

¢

0.2 r--

<P

<I>

~

~

~ Y(Ka)
-

'0

c::

l1l

0 .0
0

I

I

I

I

0 .2

0 .4

0 .6

0 .8

Tritium Concentra tion
Fig. 1. Muon loss probability W obtained from neutron
measurement, and Ka X-ray yield per fusion Y(K a ),for muon catalyzed fusion in solid D-T mixture.

Although there is one ambiguity coming from the sizeof the contribution from tt fusion, for which a measurement is under planning, Y(Ka) from dt fusion is
obtained to be around 0.24% after minor correction of
dd fusion. This value, when converted to the effective
muon sticking probability, gives Ws of between 0.45%
and 0.56% depending on the calculation selected.
Although the above mentioned analysis is not yet
final, it can be concluded that both neutron and X-ray
measurements show Ws values below or around 0.50%, which are still significantly smaller than theoreticalvalues of around 0.60%.
References
1) K. Nagamine, T. Matsuzaki, K. Ishida et al.: Muon
Catalyzed Fusion 5, 1239 (1990); Hyperfine Intaract.
82 , 343 (1993).
2) K . Nagamine, T. Matsuzaki, K. Ishida, 1. Watanabe etal.: Hyper Intaract. 85 , 1091 (1994).
3) K. Ishida et al.: RIKEN Accel. Prog. Rep. 30, 39 (1997).
4) S. N. Nakamura et al.: RIKEN Accel. Prog. Rep. 31 ,
51 (1998).
5) N. Kawamura et al. : RIKEN Accel. Prog. Rep. 31 , 50
(1998).
6) T. Matsuzaki et al. : RIKEN Accel. Prog. Rep. 30, 151(1997) .

Electrotechnical Laboratory, Japan
Rutherford Appleton Laboratory, UK

49

RIKEN Accel. Prog. Rep. 31 (1998)

Fusion Neutron Yield and Muon Cycling Rate in Muon Catalyzed
dt Fusion at RIKEN-RAL Muon Facility
N. Kawamura, S. N. Nakamura, K. Nagamine, T. Matsuzaki, K. Ishida, S. Sakamoto, M. Tanase,
M. Kato, K. Kurosawa, M. Hashimoto, K. Kudo,*l N. Takeda,*l and G. H. Eaton*2[Muon catalyzed fusion, Fusion produced neutron]
This article reports the analysis method and preliminary result of the muon catalyzed fusion (p,CF)
experiments in deuterium and tritium mixture, whichwere carried out at Port 1 of RIKEN-RAL Muon Facility. Details of the setup and the adopted detectors
are discussed in the other articles in Ref. 1.
The most essential p,CF parameters, the muon cycling rate P,c) and the muon loss rate (W) can be
deduced from fusion neutron information such a theneutron disappearance rate (An) and the neutron yield(Yn).
Figure 1 shows a typical neutron energy spectrumwith a clear 14 Me V edge which characterizes dt fusion.
The ,-ray background was removed by the pulse shapediscrimination technique.

~~• .. +. . . . . . . + ............. ;+ ............ + ............ !

I

~
lacm

8

10

12

recoiJ prooonen<rJY[MeVj

Fig. 1. A typical neutron energy spectrum. Backgroundfrom ,-ray were removed with a n-, discrimination
technique. The edge of a fusion neutron (14 MeV) canbe seen clearly.
The number of the measured neutrons with morethan the energy of 4 MeV was corrected for pileup
and multi-hit effects (0.3 and 3%, respectively) andnormalized by a solid angle of detectors (2.4 x 10- 3 )and neutron detection efficiency (10.3 ± 0.1%) to get
total neutron yield (Yn).
The neutron disappearance rate (An) can be obtained from a time spectrum (Fig. 2). The muon cycling rate (Ac) can be deduced from Yn and An as:

-01

*2

50

Electrotechnical Laboratory (ETL), Japan
Rutherford-Appleton Laboratory (RAL), U.K.

1000
500

::

100

"-

50

-;::"'

5u

10

1 ~~~~~~~~~

a

1000

2000

3000

4000

5000

6000

Time (ns)Fig. 2. A typical neutron time spectrum. Two prompt
peaks can be seen due to double pulse structure of ISIS
beam.
where ¢ denotes the normalized dt-target density.
The experiments were carried out as a series of thetritium concentration in liquid and solid phase, andthe obtained data were analyzed. Analysis is still preliminary, but no large difference has been observed between the liquid and solid phase data, except for theneutron disappearance rate at a high tritium concentration. This discrepancy might be explained with thedifference in the target volume. Total amount of tritium in our system is limited, and some of dt gas should
be remained in the buffer volume for the safety reason.
In addition to this, the vapor pressure of liquid is muchlarger than solid. Therefore a target volume of liquid
was much smaller than that for solid. Small volume of
the liquid target enhances the "wall effect": the muons,captured by a heavier nucleus in the target container
wall, could not take a part in p,CF cycle, and thus themuon disappearance rate becomes larger.
The tritium concentration (Ct ) dependence of thecycling rate (Ac) is more similar to the LAMPF result 2 )than to the PSI result 3 ) especially at high tritium concentration. Our preliminary analysis indicates that themuon cycling rate reaches its maximum value ("'-'150
p,S - l) at C t "'-' 40% in the both cases of liquid andsolid phase. Further analyses are now in progress.
References
1) RIKEN-KEK-JAERI-ETL-RAL-J-LCF
collaboration:
RIKEN-RAL Muon Facility Report 1, p. 11 (1997).
2) S. E. Jones et al.: Phys. Rev. Lett. 56, 588 (1986).
3) W. H. Breunlich et al.: Phys. Rev. Lett. 58, 329 (1987).

RIKEN Accel. Prog. Rep. 31 (1998)

K,e/K a Sticking X-ray Ratio in Muon Catalyzed dt
Fusion at RIKEN-RAL Muon Facility
S. N. Nakamura, K. Nagamine, T. Matsuzaki, K. Ishida, N. Kawamura, S. Sakamoto, M. Tanase,
M. Kato, K. Kurosawa, M. Hashimoto, K. Kudo,*! N. Takeda,*! and G. H. Eaton*2

The f.L - a sticking probability is the most crucial tothe application of f.LCF and thus, plenty of theoretical studies have been performed. However, calculations on a single molecule give only initial sticking
probability (w~) which cannot directly be comparedwith the experimentally observable, effective sticking
probability (w s ). They are associated with each otherwith a help of model calculation on collisional relaxation, stripping, and so on. These calculations require detailed information about f.La kinetics as wellas initial populations of the f.L- a atom. The observation of f.L - a sticking X rays provides such information. Ku yield provides normalization of the calculation and K(3 yield enables us to discriminate thecorrect calculation from others. For example, Cohen, Markushin, and Stodden theoretically calculated
K (3 /K u yield ratio as 0.115,!) 0.127,2) and 0.087,3) respectively. However, observation of K(3 X ray was impossible due to large bremsstrahlung background. The
world strongest pulsed muon beam enables us to measure K (3 X ray for the first time.
Figure 1 shows a X-ray energy spectrum for thetritium concentration, C t = 10%, solid dt target
with a time gate of 625 < t < 2625 ns after themuon beam arrival, which enhances f.La X rays because
bremsstrahlung background has no time structure andprompt X rays has shorter decay time. The energy
spectrum of bremsstrahlung was obtained with a time
gate of 8000 < t < 10000 ns where the beam effects had
totally disappeared. After subtracting bremsstrahlung
spectrum, the background shape can be described bya parabolic function.
The line shape of f.L - a X ray is broadened by Doppler
effects. The shape of Ko may be described by a Gaussian function, but K(3 cannot (Fig. 2). We fitted theK(3 peak with a box function whose edges were skewed
by a Fermi function to describe the K(3 shape predictedby Cohen.!)The same analysis was performed for different tritium concentration data. Obtained ratio between K(3and Ko peak areas was corrected by a difference of
X-ray attenuation.
The K(3/K o ratio is very sensitive to the way of background subtraction and its systematic error has notbeen studied enough; however, we can see some tendencies. The preliminary experimental result shows_I_2

Electrotechnical Laboratory, Japan
Rutherford Appleton Laboratory, UK

X- ray spectra of Solid Ct =10 %'::t
Raw Spectrum

"0
<1J

0.

go ., 6
en ~
o

~

'- ~
~

~ 4

lD

.,

~ ~

'- e
!l
C

E2

;::l

o
u

2 .5

5.0

7.5

10.0

12.5

\5 .0

X-ray Ene rgy (keV)

Fig. 1. Solid 10% X-ray energy spectrum with a time gateof 625 < t < 2625 ns. Bremsstrahlung background,p,- aKa" K,a X rays, and p,-t 3He X-ray candidate wereseparated.

Dopple r line shape s-

Predict ed by Cohen" /FitUng Fu n ction

0 .4- 0 .4- 0 .2

0 .0

0.2

0 .4

Shift from line center (keV)

Fig. 2. The solid lines are Doppler broadened Kc. and K,a
X-ray line shapes predicted by Cohen. I ) They were convoluted by our Si(Li) detector resolution (Kc. : (T = 116
eV, K,a : 120 eV). The dashed lines are our fitting functions to describe X-ray data.

smaller K(3/K u ratio than the theoretical values in low
C t region, while K(3/K o is larger in high C t region.
References
1) J. S. Cohen: Muon Catal. Fusion 3, 421 (1988).
2) V. E. Markushin: Muon Catal. Fusion 3, 395 (1988).
3) C. D. Stodden: Phys. Rev. A 41, 1281 (1990).

51

RIKEN Accel. Prog. Rep. 31 (1998)

RHIC Spin Project
H. Akikawa, Y. Batygin, H. En'yo, E. Fujisawa, Y. Goto, K. Hatanaka, N. Hayashi, T. Ichihara, K. Imai,
M. Ishihara, T. Katayama, T. Kawaguchi, K. Kurita, Y. Mao, A. Masaike, Y. Nakada, H. Okamura,
M. Okamura, N. Saito, H. Sakai, Y. Sakemi, T. Sakuma, H. Sato, H. Sato, T.-A. Shibata, Z. Sun,
A. Taketani, E. Taniguchi, T. Tominaka, H. Torii, T. Wakasa, Y. Watanabe,
H. Wu, M. Xiao, S. Yoneyama, and M. Yosoi[pp interaction, Structure function, Spin, Asymmetry, Polarized beam]

RHIC Spin project is the integrated efforts of accelerator physics, experimental physics and theoreticalphysics to study the polarization phenomena in highenergy hadron reactions using polarized proton beams
at RHIC. This is a report of the third year of thisproject.
For the accelerator part, a major progress was thecompletion of the prototype of the helical dipole superconducting magnet, which is going to be used as
Siberian Snakes and Spin Rotators. The performanceof the prototypes has been compared in detail in Refs. 1
and 2. Effects of beam tune shift on the polarized proton beam has been studied and the result is reported
in Ref. 3. The status of simulation of spin dynamics
in the RHIC main rings is reported in Ref. 4.
The polarization of the accelerated proton beams
will be measured with RHIC polarimeter. To verify
the current design, we have proposed an experiment at
BNL-AGS. It is approved as E925, and we received atest beam for commissioning of the detector system in
May '97 at AGS B1-line. We have designed a polarimeter for the extracted beam down to BI-line. The designconcept and its performance is described in Ref. 5.
The experimental part focused on the constructionof PHENIX Muon Arms. The magnet system forthe muon detector has been completed in Japan andshipped to BNL in April '97. Figure I shows an assembled magnet system at MELCO factory in Kobe for
excitation test. The results of factory test is describedin Ref. 6. The magnet is going to be reassembled at
PHENIX experimental hall soon and excited to thefull current to measure the field in detail for precision
momentum reconstruction.
Another major area of our efforts on the Muon Arm

Fig. 1. Muon magnet system assembled at factory.
52

is the beam test of the muon identifier system. The
test have proven the required performance of the muon
identification and pion rejection for PHENIX.7) Now
the design has been fixed, and factory setup for theconstruction is in progress at BNL and at KEK.8) Weare going to finish the construction and installation ofmuon identifier by the end of September '98.
For the timely publication of the physics output from
RHIC spin project, we are preparing both hardware
and software for omine analysis. The hardware configuration has been studied under the name of PHENIXCC-J, which means regional analysis center for the
PHENIX. The current plan is described in Ref. 9. Oneof the software development has been focused on theextraction of polarized gluon density, since it is oneof the urgent questions to be answered by RHIC Spinproject. Results of simulation studies on prompt photon analysis for extraction of gluon polarization are
described in Ref. 10.
We have formed a working group with theorists onpolarized parton distributions last year.!1) A global fitof existing data on the formula in the leading order of
perturbative QCD is in progress 12 ) using the computercode for Q2-evolution.13) The effects of structure function R(x, Q2) on the fit results have been studied inRef. 14.
References
1) M. Okamura et al.: RIKEN Accel. Prog. Rep. 31, 250(1998).
2) M. Okamura et al.: RIKEN Accel. Prog. Rep. 31, 251(1998).
3) Y. Batygin et al.: RIKEN Accel. Prog. Rep. 31, 246(1998).
4) M. Xiao et al.: RIKEN Accel. Prog. Rep. 31, 248 (1998).
5) N. Hayashi et al.: RIKEN Accel. Prog. Rep. 31, 173(1998).
6) T. Ichihara et al.: RIKEN Accel. Prog. Rep. 31, 170(1998).
7) Y. Mao et al.: RIKEN Accel. Prog. Rep. 31, 53 (1998).
8) A. Taketani et al.: RIKEN Accel. Prog. Rep. 31, 172(1998).
9) Y. Watanabe et al.: RIKEN Accel. Prog. Rep. 31, 171(1998).
10) Y. Goto et al.: RIKEN Accel. Prog. Rep. 31,54 (1998).
11) Y. Goto et al.: RIKEN Accel. Prog. Rep. 30, 35 (1997).
12) T. Yamanishi et al.: RIKEN Accel. Prog. Rep. 31, 44(1998).
13) M. Hirai et al.: RIKEN Accel. Prog. Rep. 31, 45(1998).
14) Y. Goto et al.: RIKEN Accel. Prog. Rep. 31, 55 (1998).

RIKEN Accel. Prog. Rep. 31 (1998)

Results from Beam Tests of PHENIX Muon Identifier
Y. Mao, N. Saito, Y. Watanabe, N. Hayashi, Y. Goto, H. En'yo, Y. Nakada, H. Sato, K. Imai,
H. Torii,* H. Akikawa,* T.-A. Shibata, E. Fujisawa, S. Yoneyama, and M. Ishihara[Muon identifier, Muon detection efficiency, Pion/muon rejection rate]
PHENIX is one of the two large experiments which
are going to be carried out in near future by using
the underconstructing Relativistic Heavy Ion Collider(RHIC) in Brookhaven National Laboratory (BNL).
The detection of muon, both single muon and di-muon,plays a key role to probe Quark-Gluon-Plasma with
VB = 200A GeV Au + Au collision!) and to probe
the spin structure of proton with 50 Ge V < VB < 500
GeV polarized p + p collision. 2 ) On the other hand,due to the high energy involved in the collision, thepion/muon yield ratio will be as high as 10 2 -103 in
the interested momentum region. Therefore, a highefficiency of pion/muon rejection is highly required to
PHENIX muon identifier.
Based on the conceptual design, we have constructeda prototype of the muon identifier with 2.5 m long
Iarroci tubes,3) which are the same type of tubes for
PHENIX muon identifier, to investigate the muon detection efficiency and pion/muon rejection rat e. The
prototype consisted of five detector layers, one horizontal panel and one vertical panel in a layer, sandwichedby iron slabs (180 cm x 200 cm) with thickness of 10,
10, 10, 20, 20 em, respectively. In front of the firstiron slab, we put additional iron blocks with thicknessof 10 cm to simulate the south muon arm and 20 cm
to simulate the north muon arm. The number of tubes
in each panel has been optimized to 30' of perpendicular expansion of 2 GeV muons with PISA (PHENIX
Integrated Simulation Application) v2.4 and total 54
tubes were used to construct the prototype.
The test experiment was carried out in KEK using
PI2 beam line where pion beam is obtained by bombarding an inner target with 12 GeV proton beam.
The momentum of beam, 1- 4 GeV / c is predefined by
the magnetic system acting as a momentum selector,
was used in the experiment. Figure 1 shows the experimental setup which may be described as beam
ID part and muon ID part. Four Scintillation counters, ST1 rv 4, were set to define the beam (beam =ST1 0 ST2 0 ST3 0 ST4) and 3 gaseous Cerenkov detectors, GC1 rv GC3, were set to define the muon beam
in beam ID part. GC1 and GC2 were pressured at athreshold to separate pion and muon while GC3 waspressured at a threshold to separate muon and electron, namely, muon = beam 0 GC1 0 GC2 0 GC3 andpion = beam 0 GC1 0 GC2 0 GC3. Experimentally,
we obtained that muon beam purity was better than

99% and pion beam purity was better than 99.9% if we
don't consider the muon from 7r decay after GC2. This
ensured us a precise measurement of muon detection
efficiency and pion/muon rejection rate of the muon
identifier.
All 54 Iarroci tubes were operated with "stardard"gas mixture Ar: i-C4HlO = 25%: 75%, at a high voltage of 4.8 kV. The average muon detection efficiency
of a muon ID layer is listed in Table 1. For the final construction of PHENIX muon identifier, we will
use two tubes displaced by a half cell in each panel.
Therefore, the result in Table 1 implies that a muon
detection efficiency of >96% can be expected to eachmuon ID layer. The pion/muon rejection rate has beenobtained by applying a discriminant analysis (DA) tothe experimental data and to the PISA simulation datawith a quadratic discriminant function. A comparisonof experimental result with the simulation is shown in
Fig. 2. With the simulation result , we may identify
the misidentified pion (dot-dashed line) from muonfrom 7r decay after GC2 (dash line). It is obtainedthat a pion/muon rejection rate of 1- 2% could be expected for the north muon arm and 1-3% for the southmuon arm in 1- 4 GeV / c momentum region. If we consider the center magnetic yoke as an inner absorber ofhadrons, this pion/muon rejection rate could be improved 1- 2 orders of magnitude.
Table 1. The average muon detection efficiency.
North Arm0.837 ± 0.049
0.851 ± 0.048
0.866 ± 0.049

South Arm0.854 ± 0.046
0.860 ± 0.045
0.862 ± 0.047

Momentum
1.8 GeV /c
2.0 GeV /c
2.5 GeV /c
0 .1. With GCs. D F<~ .2S

0.08

-

Simulation Data== ~Je~ti~~~n onlyO.()(jl' 0.04~ 0.02

1~.. ,,.... - - I- - -.. ~ : -:. "' : -

~r

0

0

O.S

I

IS

2

2.S

3

3.S

4

4 .S

it 0 .1

O.()(j0.04
0.Q2

0 ~~~~.J...........""""""~.....J

o OS

I

U

2 2.S 3 3.S 4
Momentum (GeWe)

4.S

Fig. 2. Pion/muon rejection rate (solid line = dashed line
+ dot-dashed line).

Beam----71sn

References......I
GC1

GC2

GC3 ST2

ST3 ST4

Fig. 1. The experimental setup.
Faculty of Science, Kyoto University

Muon ID

1) PHENIX Conceptual Design Report, BNL-48922, 1993.
2) N. Saito: Spin Physics with PHENIX Detector System
at RHIC , RIKEN-AF-Np-226, 1996.
3) E. Iarocci: Nucl. Instrum Methods Phys. Res. A 217,
30 (1983).

53

RIKEN Accel. Prog. Rep. 31 (1998)

Spin Physics with Photon Detection at PHENIX
Y. Goto, N. Hayashi, K. Kurita, and N. Saito[pp interaction, Structure function, Spin, Asymmetry, Polarized beam]

Prompt photon production in hadronic collision isan appealing probe to investigate the structure of thenucleon because theoretical interpretation for the process is clear-cut. The main contribution comes fromthe gluon Compton process, gq ----t ,q (and some fromthe annihilation process, qq ----t ,g). This provides animportant opportunity to measure the gluon content
inside nucleon.
We can investigate polarized structure of the proton
using polarized pp collision at RHIC. 1) For the collisionof the longitudinally polarized proton, the asymmetry
ALL = (dO"++ - dO"+-)/(dO"++ + dO"+-) is obtainedby using the differential cross section for parallel spin
direction (dO"++) and that for anti-parallel direction(dO"+-). The asymmetry of the prompt photon production is denoted by ALL = ~ . Ai· o'LL(gq ----t ,q),
where Ai means a ratio of the polarized to unpolarized
distributions of quark and this Ai can be measured bydeep inelastic scattering experiments. The asymmetryfor elementary process of gq ----t ,.qy o'LL(gq ----t ,q) is
calculable. As a result, we can obtain a ratio of the polarized to unpolarized distributions functions of gluon,
flGIG.
Experimentally, however, it is challenging to identify the prompt photon. First issue is extraction of theprompt photon from many backgrounds. The major
background against the measurement of prompt photon originates from the two-photon decay of 7r°'s. We
will detect photons with an electromagnetic calorimeter (EMCal) at PHENIX. The PHENIX EMCal has
a fine granularity which works powerfully to distinguish background particles. Size of one channel is0.01 in both the rapidity bin and azimuthal angle
bin. We have studied the isolation method 2 ) to distinguish them and found that we can identify prompt
photon in the region of transverse momentum (PT):
10 GeV Ie < PT < 30 GeV Ie for center-of-mass energy, y'S = 200 GeV, and 10 GeV Ie < PT < 40
Ge V I e for y'S = 500 Ge V. Table 1 shows the result of
the present estimations of yield and statistical error.
Figure 1 presents the sensitivity of our measurement
for the flG I G distribution overplotted on some model
calculations. 3)
Another issue is calibration of the EMCal. We willaccomplish it as small systematic uncertainties as possible in the measurement of cross section by implementing good enough calibration systems to use cosmic muon, and laser.
Although 7r 0 is a background for the prompt photon
measurement, it is also a good probe for the parton re-54

Table 1. Result of the present estimations of yield andstatistical error. Luminosity for the vis = 200 GeV
run is 374pb- 1 , which corresponds to the sum of thefirst and second year runs in the RHI C polarized proton
operation. That for VB = 500 GeV run is 800pb- 1 ,which corresponds to I-year run.
,fi = 200GeV

Errors on

I'lGIG

Photon PT

Yield

10 - 15 GeV/c

1.2xlOs

0.00620.046

15 - 20 GeV Ie

1.6x10'0.01680.089

ALL

20 - 25 GeV Ie

3.lx103

0.03760.171

25 - 30 GeV/c

6.9x1020.07990.309,fi = 500GeV

Errors on

Photon PT

Yield

ALL

I'lGIG

10 - 15 GeV/e

9. 0 xl0 s

0.0022

0.045

15 - 20 GeV Ie

1.8xlOs

0.00590.059

20 - 25 GeV Ie

5.3xI0·0.00810.081

25 - :30 Gf'V Ie

1.9x10'0.011·5

0.11 .5

30 - :35 GeV Ie

7.7xl030.0141O.l~135 - 40 GeV Ie

3.3x 103

0.0198

0.198

0.8

0.6

0.-4

0.2

Fig. 1. The sensitivity of our measurement for the 6t.G/G
distribution overplotted on some model calculations,where x denotes the momentum fraction carried by thegluon.

action. QCD (quantum chromodynamics) jet production is measured by detecting the leading 7r 0 , which
represents jet will provide more information on bothpolarized and unpolarized structures of the nucleon.
References
1) H. En'yo et al.: RIKEN Accel. Prog. Rep. 30, 33 (1997);
RIKEN Accel. Prog. Rep. 30, 34 (1997).
2) For example, description in G. Sterman et al.: Rev.
Mod. Phys. 67, 157 (1995).
3) T. Gehrmann and W. J. Stirling: Phys. Rev. D 53, 6100
(1996).

RIKEN Accel. Prog. Rep. 31 (1998)

Studies of Systematic Problems in the Spin Dependent
Structure Functions of the Nucleon
Y. Goto, N. Hayashi, N. Saito, T.-A. Shibata, and E. Taniguchi(Deep inelastic scattering, Structure functions, Spin]
Since the "spin puzzle" was discovered in 1987, various polarized deep inelastic scattering (pol-DIS) experiments have been carried out at CERN, SLAC, andDESY. A large amount of data have been obtained.
We accumulate the data from those experiments, investigate them systematically and reevaluate them.
The structure function g1 (= ~ L::i fl.qi) , which represents spin dependent structure function from polDIS, is not a direct observable in the experiments. The
experimentally observable quantity is the asymmetries
All and A~, where the target polarization is parallel(transverse) to the beam direction. Those asymmetries
are related to the fundamental cross section asymmetries, A1 and A2 bye;(1)
Here, V represents the photon depolarization which
involves R parameter:y(2-y)
2
V = 2(1 - y)(l + R) + y(,--+0);(2)(3)

y represents the energy function transferred to targetor y = v / E; and , represents the kinematical factor or,=Using
JQ2/v.
the cross section asymmetries, the spin dependent structure function g1 can be derived:
g1

F2

1
2x(1 + R) (A1 + ,A2),

NMC
NMC
990
gi
xV
(l + R)gl( MC <X x1)1990(1 + R1990) ,(4)

where F2 the represents the non-polarized structure
function and x represents the Bjorken x.
We have investigated the systematic problems in determining g1, which arise from the choice of R parameter and F 2 . The fitted value by EMC or a constantvalue was used for R in early times. Since 1990, theR}~;O fitted by SLAC experiment 1 ) is mainly used. As
for F 2 , the parameterization and a set of parametersof F2 by NM C has been used by most experimental(5)where, gi 990 and V1990 represent the quantities using
N MC represent those using
R1~90
Itt , while gN
1 MC and V
RN MC. The average of the ratio is 1.0028. The maximum of the ratio is 1.028.
On the contrary, when g1 is obtained from A 1, g1 is
influenced only by (1 + R)-1:+ NMC
x(l + R1990) .

g1990
x(l_____
R)_
1 _ <X ~~gl(MC1] represents the kinematical factor:

1-y1]='1-y/2;

groups. In 1995, NMC published a new set of F2parameters. 2 ) The latter parameter set fits well to thenew data.
In 1996, NMC published 10 points of RN MC in therange of 0.0045 ~ x ~ 0.110 and 1.38 ~ (Q2) ~ 20.6. 3 )We investigate the influence of g1 when R is changed
from R}~lO to RN MC. When g1 is obtained from All
and A~, 91 is influenced by V as well as by R. Therefore,(6)

In this case, the average of the ratio is 1.046, and the
maximum is as large as 1.13.
To summarize, when we obtain g1 from experimental data of All and A~, R used in 1) cancels the R usedin getting 91 from A 1. As a result, g1 is rather independent of the choice of R. However, when we obtaing1 from A 1 , we need to pay attention because g1 isaffected up to about 10% by the choice of R.
We reevaluated the data on the spin dependent
structure function of EMC and of E130 experimentbecause R has been much improved since their publications. Rflf c , not R}~;O was used in V in their
original publications. We thus obtained an appropriate asymmetry All by this reevaluation. As a resultsof this reevaluation, A1 and V are modified by about
10%.
References
1) L. W. Whitlow et al.: Phys. Lett. B 250, 193 (1990).
2) NMC, M. Arneodo et al. : Phys. Lett. B 364, 107 (1995).
3) NMC , M. Arneodo et al.: Nuel. Phys. B 483, 3 (1997).

55

RIKEN Accel. Prog. Rep. 31 (1998)

High Spin Isomer Beam Experiment at RIKEN
E. Ideguchi, Y. Gono, T. Kishida, X. H. Zhou, S. Mitarai, T. Morikawa, A. Odahara, H. Tsuchida,
M. Shibata, H. Watanabe, M. Miyake, S. Motomura, T. Tsutsumi,
B. Cederwall, T. Murakami, and M. Ishihara
NUCLEAR REACTIONS 24Mg(136Xe,a9n)147mGd,
12C(147mGd,xn)159-xYb, High spin isomer beam
Recently, large Ge arrays such as EUROBALL andGammasphere have made it possible to investigate
very high spin states. 1) Search for the hyperdeformed
states collected much attention after they were predicted in the extremely high spin states. 2) However,unambiguous experimental evidence for existence ofthe hyperdeformed states was not found yet. The mostimportant experimental difficulty seems to be how tomake such an extremely high spin state.
Secondary fusion reaction by using High Spin Isomer
Beam (HSIB) will give a solution to this problem, sincethe HSIB itself has a high angular momentum and thesecondary fusion will make much higher spin states. In
order to make very high spin states, a development of
HSIB and a secondary fusion experiment are planned
in RIKEN Accelerator Research Facility.
The most important development in the secondary
fusion experiment is getting a high yield of HSIB at
the secondary target position. Recent development of
the ion source in RIKEN made it possible to use highintensity 136Xe beam, i.e. of more than 100 pnA, which
is 10 times larger beam intensity than previously used.
It was anticipated that a usual metal foil target may
be melted by such a high intensity primary beam. In
order to avoid such a problem we have developed arotating target system.
In the secondary reaction by using HSIB, correctionof Doppler effect is also important since velocity of thesecondary beam is expected at about 10% of light velocity, which will cause a serious Doppler broadening.
A Ge telescope system was developed to decrease theDoppler broadening and to acquire a high detection
efficiency. 3)
In order to check the yield of HSIB at the final focal plane and to test the rotating target system aswell as the Ge telescope system, we have conducted
an experiment by using 24Mg(136Xe,a9n)147mGd and
12C(147mGd,xn)159-xYb for the primary and secondary fusion reactions, respectively.
The 136Xe beam was accelerated to 8.5 MeV lu by
RIKEN Ring Cyclotron. The maximum intensity of
the 136Xe beam was 260 pnA. HSIB was separated
from the primary beam and transported to the final
focal plane by RIPS. The rotating target system wasoperated under the 160 pnA and 260 pnA intensities.
The yield of HSIB was almost constant during the operation: around 6.5 x 103 in the 160 pnA intensityand 1.5 times larger yield of HSIB was obtained in the56

260 pnA run. This result implies that the rotatingtarget system was operated stably although the yieldof HSIB was 10 times less than the estimate based on
CASCADE calculations. This might be caused by thelower cross section in a9n channel than calculated. Actually, many gamma ray peaks are originated from xn
channel, and pxn channel was observed at the sametime; whose intensities were more than 10 times larger
than that of a9n channel. The axn channel also caused
the increase of momentum spread which decreased thetransmission efficiency between primary target and final focal plane.
The efficiency calibration of Ge telescope system wasmade by using 152Eu standard source. The telescope
system was located 114.5 mm apart from the gamma
source. Fig. 1 shows the result of the measurement.
The efficiency of the Ge telescope system was almost
constant ("-'2.5 x 10- 4) in the high energy region, i.e.
higher than 500 keV.

10- 2

10- 3

I

-

~

c::

I

I

I
I
o 1: Segmented Ge only
+ 2: Seg.Ge-Clover Ge Coin)( 3: OR(1+2)

• •

~-;

~
i';j

M

III

10- 4

M

i

III

:£

:-

..
f

X
:£

ip

)(

*

III

M

+
III

-::

%

'fir

10 - 5)II*'-'-.l.........L.--'--....L.....L
1--'----'---'---1.1-1. -'-'--L-,--,-I.I-.I--'--..1.-I...
1 ...L-L-L....L1-,--,--'-J'-J

250

500

750

1000

1250

1500

E" [keY)

Fig. 1. Efficiency curve of Ge telescope system. 1: Hit
only one of segment in Segmented Ge. 2: Hit both
Segmented Ge and Clover Ge. 3: OR of 1 and 2 cases.

Data analysis of the secondary reaction experimentis still in progress.
References
1) C. W. Beausang and J. Simpson: J. Phys. G 22, 527(1996).
2) S. Aberg: Nucl. Phys. A 557, 17c (1993).
3) E. Ideguchi et al.: RIKEN Accel. Prog. Rep. 27, 121(1993).

RIKEN Accel. Prog. Rep. 31 (1998)

Search for High-Spin Isomer in 143Nd
X. H. Zhou, E. Ideguchi, Y. Gono, T. Kishida, S. Mitarai, T. Morikawa, H. Tsuchida,
M. Shibata, H. Watanabe, M. Miyake, T. Tsutsumi, S. Motomura, and M. Ishihara[NUCLEAR REACTION: 18 0 + 130Te at Elab = 80 MeV; Time measurement; Half life]
The search for high-spin isomeric states has attracted much interest, because the occurrence of isomer at a high spin state would indicate a change
in nuclear properties such as nuclear shape. Highspin isomers were observed systematically in the N= 83 isotones with proton number Z from 68 to
61,1-9) the characteristics of these high-spin isomers
can be well interpreted in the framework of a deformed independent particle model (DIPM) .10) In thismodel, the sum of single-particle angular momentaof valence nucleons along the symmetry axis was
taken as the total angular momentum of the nucleus,
and the excitation energies for different configurations were calculated by the Strutinsky method. The
DIPM calculations assigned the isomers to be of thestretched configurations [v(f7 /2 h 9/2 i13/2)7r(hi1/2) lt9/2
and [V(f7/2h9/2i13/2)7r (d~!2hi1/2)lt7 for the odd andodd-odd N = 83 isotones, respectively,6) which may
induce a oblate deformation, while the low-spin states
have a near spherical shape. Therefore, these isomers
were interpreted caused by sudden changes in nuclear
shape, which was confirmed by the deformation parameters of the yrast isomers in 147 Gd deduced fromthe experimental quadrupole moments.ll) It is worth
while pointing out that the excitation energies of theseisomers in the N = 83 isotones with 61 ::; Z ::; 65 arealmost constant and around 8.5 MeV, it implies, taking the shell gap energy of Z = 64 as a parameterin the DIPM calculations, that the shell gap energies
change from 2.4 to 2.0 MeV as the proton number decreases from 65 to 61. 6) In order to extend the systematic study of the high-spin isomers in N = 83 isotones,
we have performed an experiment to search for the corresponding high-spin isomer in 143Nd with a proton
number of 60, whose level scheme was constructed up
to 10 Me V, although no high-spin isomer was reported
so far. 12 )The 143Nd nucleus was produced by using the130Te( 18 0, 5n) 143 Nd reaction at the 80 MeV beamenergy. The 18 0 beam was provided by the cyclotron at KEK-Tanashi/CNS. The target consistedof 1.8 mg/cm 2 of enriched 130Te evaporated onto a
2.8 mg/ cm 2 aluminium backing. A delayed ,-, coincidence measurement between aNal scintillator anda group of HPGe detectors was performed. The N aI
scintillator having a very large detection efficiency wasused to detect the prompt I rays corresponding to thebeam burst. Also to determine the excitation energyof the isomer, a ,-, coincidence measurement was car-ried out with five HPGe detectors with anti-Compton
shields.
For the strong I rays of 143Nd which were observedwith the HPGe detectors, their time distributions wereobtained relative to the time signal given by the NaI
scintillator. All the time distributions show a delayedcomponent, indicating the existence of a high-lying isomer. Fig. 1 presents the summation of time distributions of the 379, 421 and 791 keV I rays in 143Nd.
Unfortunately, the pulsed beam with 51 ns interval
between bursts has severely contaminated the delayedpart in Fig. 1, so a half-life value for this isomer could
not be extracted reliably from an exponential fit. At
present, only an estimated half-life of about 50 ns canbe assigned to this isomer. The data analysis to fix theposition of the isomer in terms of the excitation energy
is in progress.

(/)

C
:J

o

()

1011

500

600
Time (ns)

700

800

Fig. 1. The summation of the time distributions for the379, 421 and 791 keY 'Y rays of 143Nd, indicating theexistence of a high-lying isomer.

References
1) S. Andre et al.: Z. Phys. A 337, 349 (1990).
2) J. Mcneill et al.: Z. Phys. A 325, 27 (1986).
3) J. Pedersen et al.: Phys. Rev. Lett. 39, 990 (1977).
4) D. Hageman et al.: Phys. Lett. B 84, 301 (1979).
5) J. Borggreen et al.: Z. Phys. A 294, 113 (1980).
6) A. Odahara et al.: Nucl. Phys. A 620, 363 (1997).
7) E. Ideguchi et al.: Phys. Soc. Jpn. 108 (1993).
8) A. Odahara et al.: Z. Phys. A 350, 185 (1994).
9) Y. Zhang et al.: RIKEN Accel. Prog. Rep. 27, 32(1993).
10) T. Dossing et al.: Phys. Scripta 24, 258 (1981).
11) O. Hausser et al.: Nucl. Phys. A 443, 135 (1985).
12) O. J. Tekyi-Mensah et al.: Phys. Rev. C 50, R1759(1994) .

57

RIKEN Accel. Prog. Rep. 31 (1998)

i-Ray Linear Polarization Measurement by Segmented Ge
H. Tsuchida, Y. Gono, S. Mitarai, T. Morikawa, A. Odahara, M. Shibata, H. Watanabe, M. Miyake,
S. Motomura, T. Tsutsumi, T. Kishida, E. Ideguchi, X. H. Zhou, and M. Ishihara[NUCLEAR REACTION 139La + lOB, EeOB) = 50 MeV, 130Te + 180, E( 18 0) = 80 MeV],-ray linear polarization is a valuable information ina nuclear spectroscopic study. In the case of an inbeam ,-ray measurement to use fusion reactions, theangular momentum vectors of compound nuclei arealigned in a perpendicular plane with respect to thebeam axis. ,-rays emitted from these reaction products are then scattered by a scatterer in different directions depending on their electric or magnetic characters. A scatterer is usually placed at 90° with respect
to the beam. Analyzer detectors are placed in parallel(X) and perpendicular(Y) directions with respect tothe beam axis in a plane which is perpendicular to theaxis(Z) connecting the scatterer and a ,-ray source. In
this XYZ-coordinate, an X-axis is parallel to the beamaxis. Germanium detectors are used, in these days asa scatterer and as analyzers. Typical examples of detector set-ups to measure a ,-ray linear polarization
are described in Ref. 1.
Recently, a segmented G~ detector was prepared fora position sensitive ,-ray detection. 2 ) This detector isa planar type and has a square shape of 50 x 50 x 20
tmm 3. The ,-ray measurement using this detector
can provide information of ,-ray linear polarization byplacing this at 90° with respect to the beam axis in thein-beam ,-ray spectroscopy mentioned above. Whenone makes spectra by adding coincident signals of twosegments aligned in X or Y direction, the linear polarization information can be obtained by a ratio of thecounts of concerned peaks in these spectra. The notations of N x and Ny will be used below for the peakareas of spectra made by summing the signals fromsegments aligned in X and Y directions, respectively.
Linear polarization measurements of ,-rays in 143Nd
and 145Sm were performed by using 139LaeOB,4n)145S m and 130Tee80,5n)143Nd reactions. The lOB and180 beams of 50 and 80 MeV, were provided by the
Kyushu University tandem accelerator and the SF cyclotron of KEK-Tanashi, respectively. The segmented
Ge was placed at 70 mm from a target in the above
mentioned set-up.
The ratios Ny /N x obtained in the experiments areplotted in Figs. 1, 2, and 3. Since a linear polarization
information can be obtained in ,-ray measurements
discussed in this report, only when ,-rays are emitted
from the nuclear states with aligned angular momenta,
the ratios Ny /N x of ,-rays emitted through long-lived
isomers do not show deviations from 1. Fig. 1 shows
the Ny /N x ratios of the 133, 150, 381, and 531 keV,-rays in 14 4Sm emitted through a 880 ns isomer aswell as those of known 253 (M1) and 801(E1) keV
58

i~.rn~!'*

1.4'etYpe •• .

l

If

0 .8

*

+

0 .6

200

400

600

800
1000
Energy(keV)

1200

1400

Fig. 1. ,-rays of 144Sm below(x) and above ( +,*) long-lived(Tl/2 = 880 ns) isomer.
,,~

1.4
~1.2

{
~

,*

*

1

.~

+
0.8

.;

*+.;.

~

type : .

1200

1400

,

0.6

200

400

600

800

1000

Energy(keV)

Fig. 2. Ny /Nx ratios of previously known 3) ,-rays of
145Sm.
!Etype .......

1.4.Mtyp9

~ 1.2
">.

z
:2
"§

x

*

1
~.. +

0 .8
0.6

200

400

600

800
1000
Energy(keV)

1200

1400

Fig. 3. Ny /Nx ratios of previously known 4) ,-rays of
143Nd.

,-rays which are transitions above the isomer. The
nucleus 144Sm produced in the reaction was used to
study 145Sm simultaneously. The experimental resultson ,-rays of 143Nd and 145Sm are shown in Figs. 2
and 3, respectively. Electric and magnetic characters
were known3,4) previously for those ,-rays shown in
the figures, and they were reproduced in the present
experiments. Further analysis is in progress.
References
1) A. von der Werth et al.: Nucl. Instrum. Methods Phys.

Res. A 357, 458 (1995).
2) Y. Gonoet al.: RIKEN. Accel. Prog. Rep. 30, 137 (1996).
3) M. Piiparinen et al.: Z. Phys. A 338, 417 (1991).
4) E. Ott et al.: Z. Phys. A 348, 248 (1994).

RIKEN Accel. Prog. Rep. 31 (1998)

Measurements of Neutron Spallation Cross
Sections of 59Co and natcu
E. Kim,·1 T. Nakamura, Y. Uwamino, M. Imamura, N. Nakao, S. Shibata, and S. Tanaka*2[Neutron spallation cross section]
Neutron reaction data in the energy range above 20
Me V are quite scarce and no evaluated data file exists
at present. In this study, we have measured the neutron spallation cross section using quasi-monoenergetic
p-Li neutrons in the energy range above 20 MeV. The
experiments were performed at three cyclotron facilities of (1) Institute for Nuclear Study (INS), University of Tokyo, (2) Takasaki Research Establishments,
Japan Atomic Energy Research Institute (TIARA),
and (3) Institute of Physical and Chemical Research(RIKEN).
Irradiation experiments utilized quasi-monoenergetic neutrons which were produced by 7Li(r,nfBe reaction. The Li-targets of 2 to 10 mm thicknesses werebombarded by proton beams of 20 to 120 MeV energies from AVF cyclotron. The neutron produced in
the forward direction from the target were transported
through a collimator to irradiation samples, and theproton beams passed through the target were sweptout by a magnet and led to a beam dump. The neutron spectra were measured with the TOF method using an organic liquid scintillator. The absolute neutron
fluence was determined with the PRT (Proton Recoilcounter Telescope) at TIARA and further with the Li
activation method to detect the 7Be activity from the7Li(p,n)7Be reaction at RIKEN.
The irradiation samples were natcu and 59Co. The
samples were located at 400 cm and 837 cm behindthe Li-target at TIARA and RIKEN, respectively. Irradiation consisted of a short period (1 to 2 hrs) anda long period (about 20 hrs) by considering the halflife of produced nuclei. The gamma rays emitted fromproduced nuclei were measured with a high purity Ge
detector.
The cross sections were obtained by dividing thereaction rate with t,he peak neutron fluence which is
given by PRT or Li activation method, after correcting
the contribution of low-energy neutron components.
The errors of cross section data were evaluated fromthe error propagation law by combining the errors ofreaction rate (about 0.4-30%) , peak neutron fluence(about 12-15%) , FWHM of peak neutron spectrum(2.8- 5.0 MeV), and of contribution from the reference
cross section used to estimate the low energy neutroncomponent (about 5-92%).
We have obtained values of the cross sec*1*2

Cyclotron and Radioisotope Center, Tohoku University
Takasaki Research Establishment, Japan Atomic Energy
Research Institutetion of the 59Co(n,xn)58,57,56,55Co, 59Co(n,sp )59 Fe,
59Co(n,sp )56,54, 52 Mn, natCu(n,sp )56,54, 52 Mn, natcu_
nat CU( n,xn )64,61,60Cu,
and(n,sp) 61 ,60,58,56,55CO,
nat Cu(n,sp)65Ni reactions. As examples, Figs. 1.:....3
give cross sections of the 59Co(n,3n)57 Co, 1) natcu_(n,sp)58Co and nat Cu(n,sp)56Mn reactions, respectively. The results are compared with the calculated
results by Odano 2) and Fukahori. 3,4) Our experimental
results in the energy range above 40 MeV are the firstexperimental data, and are generally in good agreement with the calculated data.

I

j
8

10'

10' 0~"""'20~4OL...........-:'::60"""""""'80""""""""""'100---..J120

Neutron Energy [MeV]Fig. 1. 59Co(n,3n)57 Co reaction cross section.

I.§.

10'

tf t

6

]

~

U

10' '---........L~---'-~L...........~---1
o 20 40 60 80 ~ 120

Neutron Energy [MeV]Fig. 2. nat Cu(n,sp ) 58 CO reaction cross section.
10' , - - -- - - -- - - ,

I
6

]

10'

~

u

10·' U-'-_.....:::===:::::::~
20
40
60
80
100
120
Neutron Energy[MeV]Fig. 3. natCu(n,sp)56Mn reaction cross section.

References
1) Y. Uno et al.: Nucl. Sci. Eng. 122, 247 (1996).
2) N. Odano and S. Iwasaki: JAERI-M 94-019, p. 310;
Proc. 1993 Symp. On Nuclear Data (1994).
3) T. Fukahori et al.: JAERI-M 92-039, p. 114 (1992).
4) M. Blann: CODE ALICE/89, private communication(1989).
59

RIKEN Accel. Prog. Rep. 31 (1998)

Polarization Observables for the 3He( d, p )4He Reaction
T. Uesaka, H. Okamura, T. Ohnishi, Y. Satou, S. Ishida, N. Sakamoto, H. Otsu, T. Wakasa,
T. Nonaka, G. Yokoyama, K. Itoh, K. Sekiguchi, T. Wakui, and H. Sakai
3He(d,p)4He, Ed = 270 MeV, Measured analyzing powers,[ Measured polarization correlation coefficients
We have proposed a new experimental approach to
study the high momentum component of the deuteronD-state wave function by measuring the polarization
correlation coefficient, Gil, for the 3He(d~p)4He reaction. The first experiment was carried out at RIKEN
Accelerator Research Facility in 1996. 1 ) In this report,
the experimental results and its comparison with therelated experimental data are presented.
Experimental result of Gil , which is expected to be
proportional to the D-state density, is plotted together
with Plane-Wave Born Approximation (PWBA) calculations in Fig. 1. The experimental data is significantly
smaller than what are predicted by the plane wave calculations. If we interpret this result as it is, the D-state
density is reduced to be almost one third. However, it
is hardly acceptable. That is, the reduced Gil should
be due to the complexity of reaction mechanism. A
multiple scattering effect or a quark exchange effectmight be examples of such candidates. Indeed, theseeffects are considered to be quite important to describe
the observed discrepancies in the polarization observabIes for the d+p backward scattering (DPBS) and forthe deuteron inclusive breakup (DIB) reaction 2 ,3) The
large discrepancy between experiment and theory in
Fig. 1 leads to the conclusion that the Gil is sensitive
to these reaction-mechanism effects , and therefore we
can use Gil to test the given reaction models.
We compare the individual components of Gil, A yy ,Gy ,y, and Gx ,x, with polarization observables for DPBS
and DIB. The expressions of T 20 and "'0 for DPBS andDIB have similar forms as those of Ayy and Gy,y (Gx ,x)for the 3He(d~p)4He reaction, respectively.5) This similarity can be understood from the common nature of

1.00

075

- - - - - - --

1

0 .5
0 .0

g
Eo<

-0.5
- 1.0
-1.5
1.0
0.5

0

Io!

0.0

- .. ... .. .........

-0 .5

IA calculation-1.0 L.....-'--'--.o........J.-'---'--"'---'--"'-~-'--"""~.....J
0 .6
0. 0
0 .2
0.4

q [GeV Ie]

Fig. 2. Comparison of the present data (filled stars)
with polarization observables for the d+p and deuteronbreakup.
As for the present experimental data,-v'2Ayy and -1.5Cy,y (-1.5C x ,x) are plotted insteadof T20 and "-0, respectively. Open symbols denotethe data for the d + p backward scattering, and filled
symbols indicate the data for the deuteron inclusive
breakup on hydrogen target. 4 ) Solid curves denoted by
IA are plane-wave calculations.
these reactions: one nucleon exchange. In Fig. 2, thecomparisons among these three reactions are shown.
For comparison, the present results are multiplied byfactors -v'2 and -1.5 for Ayy and Gy ,y (Gx ,x ), respectively. A similarity can be seen in the cases of both
T 20 and "'0: - v'2Ayy has a large negative value andis less negative than the plane-wave calculation as T20
for DPBS and DIB is. - 1.5Gy ,y (-1.5Gx ,x) has a positive value as "'0 does. These facts suggest that thepolarization observables for the 3He(d~p)4He reaction
are expected to give us significant information on theunsolved problems encountered in the DPBS and DIB
experiments.

0 .50

0.25

O. OO L.......~~...!-~~o..-L~~~1-....~~...L..-~

o

10

20

30

40

8 em [degree]Fig.
1.
The experimental result (filled star) andplane-wave calculations of C II . The solid and broken
curves are calculations with the Paris and Bonn potentials, respectively.
60

References
1) T. Uesaka et al.: RIKEN Accel. Prog. Rep. 30, 46(1997).
2) A. P. Kobushkin, A. 1. Syamtomov, and L. Ya. Glozman:
Preprint ITP-95-9E 1995 (LANL hep-ph 9503435) .
3) M. G. Dolidze and G. 1. Lykasov: Z. Phys. A 336, 339(1990).
4) L. S. Azhgirey et al. : Phys. Lett. B 391, 22 (1997), andreferences therein.
5) T. Uesaka et al.: Doctor Thesis (Univ. of Tokyo), 1997.

RIKEN Accel. Prog. Rep. 31 (1998)

Study of Spin Flip Signatures via 12C(d, d') Reaction
S. Ishida, Y. Satou, H. Sakai, H. Okamura, H. Otsu, N. Sakamoto, T. Uesaka,
T. Wakasa, T. Ohnishi, T. Nonaka, G. Yokoyama, T. Niizeki,
T. Ichihara, K. Hatanaka, and N. Nishimori*[NUCLEAR REACTION 12C(d~di), Ed = 270 MeV, Measured 81, S2 and other signatures]
Inelastic deuteron scattering should be the most efficient probe to study the isoscalar spin excitations,because it excites exclusively the isoscalar states. I- 3 )Moreover, the measurement of the deuteron spin flip isneeded to separate the spin strength from the non-spinstrength. The first polarization transfer measurement
by using the newly developed focal plane Deuteron POLarimeter DPOL 4) has been carried out on 12C. A partof the result was previously reported. 5 ) Further mea,surements on this reaction have been carried out toimprove poor statistics of the double scattering measurement. The analysis including new measurements
is now in the final stage.
DPOL is designed to measure all the vector and tensor polarization components within the single counter
configuration of the polarimeter, so that one can determine all the eight polarization observables with respect. .In one measure ment:·I.e., pyl 'Y'
A pyl y' ,yy,At o y aXIS
K~/, K~~yl, K~/Y ' and K~~, where y and yy denotethe vector and tensor polarization, respectively. The
probabilities of non-spin-flip (So), spin-flip (Sd, anddouble-spin-flip (82 ) are extracted from these polarization observables asSo

1

I 2 C has the unnatural parity states 1+ at 12.71 MeV
and 2- at 18.3 MeV in the measured Ex region, which
are known as isoscalar spin states, and also the naturalparity states such as 2+ at 4.44 MeV, 0+ at 7.65 MeV
and 3- at 9.64 MeV.
The preliminary result of the measurement is shownin Fig. 1. The spin flip probability S1 has large values
for the unnatural parity 1+ and 2- states, and the S2values are around 0 for all excitation energy region.
Further analysis is now in progress.

30000

2+
20000

12C(d,d') at 270 MeV,
2.5 - 7.5 deg.

10000

0 ,4

0 ,2
0 ,0

-0 .2 1-+--+-+-+--+-+-+-+-+-+-+-+--1I--+-+-l---+-+-+-+-t:....r-t--+-:!
0 .4

0.2

-6 (2 + 3KYy + KYyY'y)I

I~ (4 - pylyl - A
9

1

yy

I

- 2Kylyl)yY'

Ex (MeV)-18 (4 + 2PY y + 2A yy - 9KYy + KYyY'
y
I

I

I

I

')

where the subscript ,6.m of the spin transfer probability
8D.m is the change in Sy. The spin flip probability Sl
in the (d,d') reaction will be a good signature of thespin excitations as 8 nn is in the (p,p') reaction.
The experiment was performed with a 270 MeV
deuteron beam for the excitation energy range of about
3 < Ex < 25 MeV. DPOL was installed in the second
focal plane of the spectrograph SMART. The beamswinger magnet was set at 50, which covers the angular range of 2.5 0 < (}zab < 7.5 0 • The target nucleus

Fig. 1. Excitation energy spectrum, the spin flip probability 8 1 and the double spin flip probability 82, for the
scattering angle 2.5 0 -7.5 0 •References
1) S. Ishida et al.: Phys. Lett. B 314, 279 (1993).
2) M. Morlet et al.: Phys. Lett. B 247 228 (1990); M.
Morlet et al.: Phys. Rev. C 46 1008 (1992); B. N.
Johnson et al.: Phys. Rev. C 51 1726 (1995) .
3) C. Furget et al.: Phys. Rev. C 51 1562 (1995).
4) S. Ishida et al.: AlP Conf. Proc. 343, 182 (1995).
5) Y. Satou et al.: RIKEN Accel. Prog. Rep. 29,57 (1996).

Japan Atomic Energy Research Institute61

RIKEN Accel. Prog. Rep. 31 (1998)

Measurement of the 28Si(il, il') Reaction at Ed = 270 MeV
Y. Satou, S. Ishida, H. Sakai, H. Okamura, N. Sakamoto, H. Otsu, T. Uesaka, T. Wakasa,
T. Nonaka, T. Ohnishi, G. Yokoyama, K. Sekiguchi, K. Yakou, S. Fukus aka ,K. Itoh, T. Ichihara, T. Niizeki, and K. Hatanaka[NUCLEAR REACTION, 28Si(ct: J), Ed = 270 MeV]
In the past three decades much of magnetic transitions and spin giant resonances has been investigatedby using various nuclear reactions such as (e, e' ), (p,p')and (p, n). These reactions preferentially excite isovector (I:::..T = 1) transitions. Therefore, the understanding of the isoscalar spin excitations (I:::..T = 0, I:::..S = 1)
is still limited. The (d~ dl ) reaction at intermediate
energies is considered to be a promising tool for the
study of I:::..T = 0, I:::..S = 1 transitions, because (a) it
exclusively excites the isoscalar states, (b) the reaction
mechanism becomes selective in spin-flip transitions atenergies above 100 MeV/nucleon, and (c) the spin-flip
probability SI, obtained by measuring the polarizationtransfer observables, is useful in separating the spinflip (I:::..S = 1) and non-spin-flip (1:::..8 ::::: 0) strengths.
The feature (c) has been established by the previous
experimental study of the 12C(d~ J) reaction.1)
In this report we describe our experimental studyof the isoscalar M1 (1+) states via the 28Si(ct: dl ) reaction. The nucleus, 28Si, is known to have at least
one isoscalar spin-flip state (J7r = 1+, 9.5 MeV) whichis strongly excited in the (p, p') reaction. 2) The differential cross sections (~~) and eight spin observables(Ay, A yy , pyl, pylyl, K~', K~'Y', K~~ and K~~yl)
were measured over an angular range from 2.5 0 to 7.5 0
and an excitation energy range from 4 to 24 MeV. A
270 MeV polarized deuteron beam from the RIKEN
Ring Cyclotron was used to bombard a 58.1 mg/cm 2thick natSi target (28Si: 92.2%, 29Si : 4.7%, 30Si
: 3.1%). Typical beam intensity was 10 nA. The
scattered deuterons were momentum analyzed by amagnetic spectrometer, SMART, and their polarization components were determined by the asymmetry
measurement using a polarimeter, DPOL,3) which wasplaced in the second focal plane (FP-2) of SMART.
The elastically scattered deuterons and the deuterons
that excite the target nucleus to the first 2+ state at
1.78 Me V were removed by a 5-cm thick lead slit located at the intermediate focusing point of SMART.
Figure l(a) shows the excitation energy spectrumof natSi target. The isovector 1+ states, which usually dominate in the forward angle (p, p') spectra,
are entirely suppressed based on the isospin selection
rule. All the levels observed are, therefore, isoscalar(I:::..T = 0) states. A prominent peak was observedat the excitation energy of 18.8 MeV. To the best of
our knowledge, no J7r assignment has ever been done
for this peak structure. Since this peak had already

62

(0)

6=2.5°-7.5°

III
C

:l

o
U

o~:=:::::::::::;::::::==~::::::::==:=:

i:~~~
~

to

15

20

Excitation' enero), ( .... V)

Fig. 1. Experimental results of the deuteron inelastic scattering from 28Si . (a) Measured excitation energy spectrum. (b) Spectrum of the tensor analyzing power, A yy .

been observed in the (0',0") experiment ,4) it may beascribed to a non-spin-flip state (or a resonance). The
previously known isoscalar 1+ state at 9.5 MeV isclearly excited. Figure 1 (b) shows the excitation energy spectrum of a tensor analyzing power, A yy . The
Ayy takes negative values for the 1+ state at 9.5 MeV,
indicating the spin-flip nature of this state. As one
sees, Ayy also becomes negative at Ex ~ 8.3 MeV and10.6 MeV. At the former excitation energy region, an
isoscalar (T = 0) 1+ state has been known on thebasis of ,-decay systematics. 5) At the latter region,
two isovector (T = 1) 1+ states have been known at
10.60 and 10.73 MeV. These levels were regarded asa mixed analogue of the 28 Al 1.37 MeV state, and it
has been expected that they have appreciable T = 0
components. 5)
Further analysis is under progress to deduce theother spin observables. The spin-flip probability 8 1 ,obtained through the relationship,
1
I
I
I
I
81 = 9(4 - Ayy - Py y - 2Kt/ ),is expected to play an important role in identifying
the isoscalar spin-flip strengths in a more definitive
manner.
References
1) Y. Satou et al.: RlKEN Accel. Prog. Rep. 30,45 (1997).
2) G. M. Crawley et al.: Phys. Rev. C 39, 311, (1989).
3) S. Ishida et al.: RlKEN Accel. Prog. Rep. 29, 179(1996).
4) H. Riedesel et al.: Nucl. Phys. A 454, 85 (1986).
5) P. M. Endt: Nucl. Phys. A 521, 1 (1990).

RIKEN Accel. Prog. Rep. 31 (1998)

Gamow-Teller Strength Distribution in fp Shell Nuclei
T. Niizeki, s. Fukusaka, T. Ichihara, S. Ishida, K. Itoh, T. Ohnishi, H . Ohnuma,
H . Okamura, H . Orihara, H. Sakai, N. Sakamoto, Y. Satou, K. Sekiguchi,
Y. Tajima, T. Uesaka, K. Yakou, and G. Yokoyama[NUCLEAR REACTION (d,2He), GT (3 decay]
The (d,2He) reaction at intermediate energy is very
useful to measure the (3+ Gamow-Teller transition
strength, B(GT+). This reaction excites spin-isospin
states selectively. This reaction has advantages in efficiency and energy resolution 1) over other reactions
such as (n,p). Because of these advantages, we canmeasure GT + transitions to the discrete states inintermediate-mass nuclei.
We have carried out the (d,2He) reaction experimentat Ed = 270 MeV to obtain B(GT+) on N = 29 isotones. Obtained energy spectra at 0° are shown in
Fig. 1 as a function of (3 decay Q-value, Q,B. 54Mn,
52V, 51Ti and 50SC spectra are shown to be comparedeach other. We used a sheet of 50Ti enriched thin foilof 1. 7 mg/ cm 2 thickness to obtain the 50SC spectrum.
We can use such a thin target ·of 50Ti because of theenough efficiency of our (d,2He) experiment.
These spectra are preliminaries. Therefore, we see
only the outline of these spectra. The shaded peaks
show the GT + state candidates which are excitedstrongly at e = 0°. From the angular distributionsof the cross sections, these peaks can be identified as
GT + states. On 52V spectra, three peaks of similar
strength can be seen and these are distributed rather
widely than other nuclei. On 54Mn, 51Ti and 50S c
spectra, substantial strong peaks can be seen. On 50Sc
spectrum, a significant peak stands and there is noother substantial peak.
Energies of the low-lying peaks decrease with proton
number. Strength of that peak increases with proton
number. This feature has been suggested for the caseof N = 15 isotone. 2) Further analysis and the comparison with shell model and with other reactions should
be carried out.

2()()
150
100

50
0
90

60
30

... 0
r;n

Q

=='

0

U

90

60

30
0
30
20
10

0

0

10

5

Q13

15

20

(MeV)

Fig. 1. The energy spectra of N = 29 isotones obtained bythe (d,2He) reaction. Horizontal axis is the excitationenergy converted to the J3-decay Q-value. Vertical axis
is the counts per channel. The top spectrum is obtainedby the 54Fe(d,2He)54Mn reaction. The lower panels are
52V, 51Ti and 50SC spectra, respectively. The shaded
peaks are candidates of GT + states.

References
1) H. Okamura et al. : Phys. Lett. B 345, 1 (1995);
H. Ohnuma et al. : Phys. Rev. C 47, 648 (1993).
2) T. Niizeki et al.: Nucl. Phys. A 577, 37c (1994) .

63

RIKEN Accel. Prog. Rep. 31 (1998)

Low Background Measurement of 8B Coulomb Dissociation
M. Hirai , T. Kikuchi, T. Motobayashi, T. Minemura, S. Shimoura, H. Murakami, Y. Ando , K. Ieki,
T. Nishio , Y. Yanagisawa, M. Suzuki, H. Fujiwara, T. Uchibori, Y. Iwata, H. Sakurai,
Y. Watanabe, K. 1. Hahn, H. Utsunomiya, K. Miki, S. Kubono, T . Teranishi,
N. Aoi, T. Nakamura, M. Ishihara, M. Gai, and E. L. Wilds*[NUCLEAR REACTIONS: 20Bpb(BB, p7Be)20BPb, Coulomb dissociation]
Directly relating to the solar neutrino problem, studies of the reaction 7Be(p,,)BB in sub-MeV energy region are very important. The Coulomb dissociation
reaction 20Bpb(BB , p7Be)20BPb, in the intermediate energy region is a powerful tool for that study. We havealready performed two experiments of BB dissociation
at RIKEN in '91 and '94 , and extracted the S-factors
within the range of 0.5 < Er el < 2.0 MeV. 1 ,2)Here we report the third experiment performed in'96, which aimed at measuring the S-factors in thelower energy region by improving the setup to achievea lower background measurement. The present experiment is expected also to measure the angular correlation between the fragments, which may be affected
possible E1-E2 interference. 3 )Figure 1 shows the experimental setup.

208Pb Target(50mg/ cm 2 thick)

0.96 x 1 m 2 • The complete kinematics of the pJBe
system were reconstructed by using the detected positions on the hodoscope and the time-of-flight from
Tgt-PL to the hodoscope.
In the two former experiments, a helium gas bag
was inserted between the target and the hodoscope,
but we have found it to be created many background
events. In the present experiment, we installed a vacuum chamber, and the space between the target chamber and the hodoscope was evacuated. A mylar foil
(200 J-£m) was placed at the end of the chamber, leaving 10-15 cm of the air gap between the mylar foil andthe hodoscope.
Figure 2 shows spectra of the relative energy E relof the p-7Be system. The data obtained with the leadtarget and the background data obtained without thelead target are shown in Fig. 2(a). Figure 2(b) shows
the background-subtracted spectrum. Solid line represents the result of a Monter-Carlo simulation, donewith a constant S-factor of 20 eV-b.
0 .30
0 .25
(a)
0 .20
~ '>
0.15
~
0 .10
0.05
it Eo.00 !++++-If.-+-+++t+-+-t-H=+RF=F=f._-++ot-t-t--t--'l>.~(b)g ~ 0 . 15eu"Target Chamber /55 NaI (T1) Array
4.3m

IOcm

CIJ

Fig. 1. Schematic view of the experimental setup.

]0 . 10

W

0 .05
0.00

The secondary beams, which contain BB as a dominant component (2/3), were provided by the RIPS
fragment separator.
The energy of BB was 52.5
MeV /nucleon, and the intensity was 2 x 105 cps on
average.
The secondary beams bombarded a 50 mg/ cm 2
208Pb target which placed at the third focal point at
RIPS. A 0.5 mm thick plastic scintillator (Tgt-PL)
was also placed in the target chamber, adjacent to
the target itself. Fifty-five NaI(TI) scintillators 4 ) havesurrounded the target to detect the , rays emittingfrom the excited fragment 7Be* in the 1/2- states at
429 keV with a branching ratio of approximately 5%.2)
About 4.4 m downstream of the lead target, weplaced a counter hodoscope which consisted of 13(~E)
and 18(E) plastic scintillators, and detected p and 7Be
in coincidence. The effective area of the hodoscope is
Department of Physics, Yale University, U.S.A.

64

o

0 .5

1.5

2

2 .5

3

Relative Energy [MeV]Fig. 2. (a) Relative energy spectra taken with and without
the target. (b) Background-subtracted spectrum andthe Monte-Carlo estimation with a constant S-factor of
20 eV-b (solid curve) .
Premilinary results of the angular correlation exhibit
some asymmetries, which will be analyzed in terms of
the interference discussed above.
References
1) T. Motobayashi et al. : Phys. Rev. Lett. 73, 2680 (1994);
N. Iwasa et al.: J. Phys. Soc. Jpn. 65, 1256 (1996).
2) T. Kikuchi et al.: Phys. Lett. B 391, 2680 (1997).
3) H. Esbensen and G. F. Bertsch: Phys. Lett. B 359, 13(1995); Nucl. Phys. A 600, 37 (1996).
4) T. Nishio et al.: RIKEN Accel. Prog. Rep. 29, 184(1996).

RIKEN Accel. Prog. Rep. 31 (1998)

Measurement of Cross Sections of the BLi(a,n)llB and BLi(a,an)7Li
Reactions with a New-MUSIC Detector
Y. Mizoi, T. Fukuda, Y. Matsuyama, T. Miyachi, H. Miyatake, N. Aoi, N. Fukuda, M. Notani,
Y. X. Watanabe, K. Yoneda, H. Sakurai, Y. Watanabe, A. Yoshida, and M. Ishihara[Nuclear Reactions BLi(a,n)l1 B, BLi(a,an)l1 B; Elab=2- 7 MeV; Measured a(E)]We have measured the cross section of theBLi(a,n)l1 B as well as BLi(a ,anfLi reactions with a
New-MUSIC 1 ) detector system in coincidence with theneutron in order to identify the final states of BLi(a,n)
reactions. We report the present status of the analysis.
The BLi(a,n)l1 B reaction is one of the key processes
in the primordial nucleosynthesis which is describedby inhomogeous big-bang models. Historically, thisreaction was studied by using the inverse reaction,
11 B(n,a)BLi.2) In addition, a direct measurement of theBLi(a,n)l1 B reaction 3 ,4) was performed by a MUSICS)
detector. The cross section of the former measurement
is smaller than the latter measurement by a factor of 5.
This difference is explained by the fact that the former
includes only a ground state of 11 B, while the latterincludes all states of 11 B.
In addition to the BLi(a,n)l1 B reaction, theBLi(a,an)7Li-breakup reaction can occur above 2.0
Me V at the center of mass system. To estimate thecontributions of each 11 B state and of breakup channel to the cross section, we' have performed for the
first time the exclusive direct measurement of theBLi(a,n)l1 Band BLi(a,an)7Li reactions with the NewMUSIC detector.
The New-MUSIC detector is a MUSIC (MUlti- Sampling Ionization Chamber)-type detector, which canmeasure the energy loss along the particle track. The
main advantage of the New-MUSIC is its capability towork as a time-projection chamber employing flashADC's (Analogue to Digital Converter) to identify
multi-track events. This advantage is effective to reject the background events and also to identify the final
channels like the BLi(a ,anfLi reaction.
The experiment was performed with RIPS at
RIKEN Ring Cyclotron Facility. The BLi beams were
produced by a fragmentation reaction of the 12C beams
at an energy of 70 MeV/nucleon. The energies of BLi
beams were degraded by AI-plate degraders to 10- 30
MeV. The energies of BLi were determined event by
event through a time of flight measurement. The BLi
beams were irradiated into the New-MUSIC detector
filled by the gases of 4He admixed with 5%(10%) of
iso-butane at 400 torr pressure. The 4He gas works
as a detector gas as well as a target. Neutron counters surrounded the New-MUSIC detector from 0 to 90
degree.

Figure 1 shows the cross sections of theBLi(a,n)l1 B(all states) and BLi(a,an)7Li reactions.
The threshold energy of the analysis is set to be 2.0
MeV at the center of mass system, because we have difficulties to identify the reactions at the present stageof the analysis. It is found that the escape channel,
BLi(a,an)7Li has a comparable cross section to theBLi(a,n)11 B channel. In order to determine the absolute cross sections, we need yet to estimate the efficiencies by computer simulations.
~ 0 .7 c:-------~--:-;---;--------,

Li

{

0 .6
0.5
0 .4
0.3
0 .2

0.1

~

0.7

~---------:------:--------,

Li

{

0 .'6

0,5

8Li(o: ,o:n)7Li

.0.4
0.3
0 .2

0.1

o0

7
Ecm (MeV)

Fig. 1. The upper spectrum shows the total cross section(0-) of the 8Li(a,n)l1B reaction. The lower spectrum
shows the 0- of 8Li(a,anfLi. The x-axis represents
E c. m.(MeV) The y-axises of the both spectra are relatively normalized.

At the present stage of the analysis, a half of thetotal events were analyzed. The further analyses are
now in progress. We will determine the absolute crosssection of these reactions and branching ratios.
References
1) Y. Mizoi et al. : RIKEN Accel. Prog. Rep. 30, 143(1997).
2) T. Paradellis et al.: Z. Phys. A 337, 211 (1990).
3) R. N. Boyd et al.: Phys. Rev. Lett. 68, 1283 (1992).
4) X. Gu et al.: Phys. Lett. B 343, 31 (1995).
5) K. Kimura et al.: Nucl. lnstrum. Methods Phys. Res. A
297, 190 (1990).

65

RIKEN Accel. Prog. Rep. 31 (1998)

Density Distribution of 9C Derived from Reaction Cross Sections
M. Fukuda, M. Mihara, T. Fukao, M. Tanigaki, T. Onishi, K. Matsuta, Y. Nojiri, T. Minamisono,
T. Ohtsubo, S. Fukuda, S. Ito, T. Kobayashi, S. Momota, A. Ozawa, T. Suzuki,
1. Tanihata, K. Yoshida, M. Ishihara, and T. Nakamura
NUCLEAR REACTION: Be(12C, 9C), E = 135 MeV/nucleon, Measured
9C reaction cross sections, Deduced 9C density distribution
The nuclear structure of the proton drip-line nucleus
9C has attracted much interest ever since its magnetic
moment was found to be anomalous.!) It is important
to determine the density distribution of 9C for studies
of its nuclear structure. In order to investigate the density distribution of 9C, we have measured the reaction
cross sections ((7R' s) for 9C on the Be, C, and Al targets at .the beam energies of 40 and 70 MeV/nucleon
using the transmission method. The methods of theexperiment and analysis were essentially the same as
the ones in Ref. 2 in which BB was studied.
The unstable nuclear beam of 9C was produced by
the projectile fragmentation of the 135 MeV/nucleon
12C primary beam provided from the RIKEN Ring
Cyclotron. The nuclide selection was made throughthe RIPS (RIken Projectile fragment Separator). The
beam energy of 40 MeV/nucleon was chosen to gain
large nucleon-nucleon total cross sections that areabout three times of those at the LBL energies whichwere around 700 MeV /nucleon. 3 ) At 70 MeV/nucleon
the cross sections take approximately the middle values in between these two energies.
The particle counting and identification before thereaction target were done by a thin Si counter for~E measurement and three parallel plate avalanche
counters (PPACs) that provided the time and position
information. Downstream of the reaction target, theidentification was made from ~E taken by Si countersand from the time-of-flight (TOF) taken in between
the PPACs and plastic counters which were placed 2
m downstream from the reaction target. The energy
loss in the reaction target was about 20 MeV/nucleon
for both energies.
In order to connect the experimental reaction crosssections (7R to the density distribution of 9C, we employed the Glauber-type calculation. 2) An enhancement factor was introduced for the calculations at theintermediate energy range. This factor was the sameas the one 2) used in the study of BB and deduced fromthe (7R data for other stabler nuclides such as 6Li, 7Be,
and 12C, whose densities can well reproduce the interaction cross sections at high energies. 3 )We assumed a shape of the density distribution of 9C
and fitted it to the (7R data including the high-energy
data through the Glauber-type calculation. The assumed shape for the proton density in 9C was a Gaussian at the core and a Yukawa-square tail at the outerregion, while that the neutron density was only a Gaus-

66

sian with the same width as the proton core. The preliminary result is shown by the shaded region in Fig. 1,
where the best-fit density is shown by the dashed curve
and the error is indicated as the height of the shade.

10.7 L...--L-I...-L---L-.L....-L.-'-.J.......J..---L-..I......J..--L-..L.-J.-I-...L....I.-'-....L-...L--.J.-...I
2
12
o
4
6
10
8

r (fm)

Fig.
1.
Density distribution of 9C derived by afitting to the experimental CTR data (dashed curve)
and single-particle calculated densities (dotted anddash-dotted curves). The shaded region indicates theexperimental error.

The dotted curve in Fig. 1 shows a single particle
density for one proton in 1p orbit in the Woods-Saxon
potential, the depth of which was adjusted to reproduce the experimental one-proton binding energy of
1.296 MeV for 9C. The dash-dotted curve shows a similar single particle calculation for two protons in 2s orbit
with the binding energy of 1.433 MeV, in which the two
protons are assumed to form a single cluster. Though
the present density has a large error, these simple calculations with the realistic proton binding energies arecompared to show a good agreement with the best-fit
density as shown in Fig. 1. These densities have 5- 10
times smaller amplitude at the tail region compared tothe case of BB.
References
1) K. Matsuta et al.: Nuc!. Phys. A 588, 153c (1995).
2) M. Fukuda et al.: RIKEN Accel. Prog. Rep. 30, 54(1996).
3) A. Ozawa et al.: Nucl. Phys. A 608, 63 (1996) .

RIKEN Accel. Prog. Rep. 31 (1998)

Inelastic Proton Scattering on 12Be in Inverse Kinematics
H. Iwasaki, T. Motobayashi, H. Akiyoshi, Y. Ando, N. Fukuda, H. Fujiwara, Zs. FUlop, K. I. Hahn,
Y. Higurashi, M. Hirai, I. Hisanaga, N. Iwasa, T. Kijima, T. Minemura, T. Nakamura, M. Notani,S. Ozawa, H. Sakurai, S. Shimoura, S. Takeuchi, T. Teranishi, Y. Yanagisawa, and M. Ishihara
NUCLEAR REACTIONS: 1H,208Pb(12Be, 12 Be,) 1H,2°8Pb,[ E(12Be) = 54 A MeV; Deduced deformation parameter f32
Collective behavior of the even-even nuclei has beenstudied through measurements of the reduced transition probability B(E2 ; 0+ 98 .-+2+). As well as electromagnetic processes such as Coulomb excitation and ,decay lifetime, the inelastic proton scattering has beenstudied for estimating the B(E2), where the interaction between the proton and the nucleus of interest isdominated by the nuclear force. 1) Differences between
the results obtained from the inelastic proton scattering and the electromagnetic probes were discussed interms of the ratio of neutron- to proton- transition
matrix elements M n/ M p' 2,3) We have investigated theinelastic proton scattering in the inverse kinematics exciting the neutron-magic nucleus 12Be to its first boundexcited 2+ state, where the B(E2) is unknown. Here
we report the experimental arrangement and preliminary results.
A 12Be beam was produced by using the projectile
fragmentation of a 100 A MeV 18 0 beam incident on
aLII g/cm 2 Be target. By the RIKEN Projectilefragment Separator (RIPS), the 12Be beam was separated with a high purity of around 96%. The secondary beam intensity was typically a few tens of thousands counts per second with the momentum spread± 1%. Two 1.0 mm thick plastic scintillators (PL)were located at the first achromatic focal plane of the
RIPS (F2) and at the final focal plane (F3). Two parallel plate avalanche counters (PPAC's) were placed at
F3 to determine the incident angle of the beam. The
particle-identification of the incident beam was carriedout event-by-event with the time-of-flight (TOF) measurement. The TOF was determined between F2-PL
and F3-PL timings. The secondary 12Be beam bombarded a 90.2 mg/cm 2 thick (CH 2 )n target at F3, with
its average energy on the target 53.8 A MeV. The background originating from the 12Be + 12C scattering wasmeasured using a 89.8 mg/cm 2 thick 12C target andsubtracted from the (CH 2 )n yields. In order to study
a possible contribution of the Coulomb force, measurements with a 351 mg/cm2 thick 208Pb target were also
performed.
The scattered 12Be was detected by a hodoscopeconsisted of 13 !:l.E- and 16 E- plastic scintillators, located 4.9 m downstream of the target. This hodoscope
was mounted on a vacuum chamber, details of which
are described elsewhere,4) for reduction of background.
The particle identification was performed in the stan-1

dard !:l.E-E method. The scattering angle was determined by the hit positions at the two PPAC's andthe hodoscope. The de-excitation "( rays were detected with 55 pieces of NaJ(TI) crystal scintillators
surrounding the target from 60 to 163 degree. Eachscintillator crystal has a rectangular shape with thesize 6 x 6 x 12 cm 3 coupled with a 5.1 cm ¢ photomultiplier tube. The energy resolution was typically 7.0%
FWHM for 1275keV, ray as calibrated from the 22Na
standard source.
To test of the validity of the method, we performed
the same measurements with 59 A MeV lOBe, where
the B(E2) is known.
Figure 1 shows the ,-ray spectrum obtained in coincidence with inelastically scattered 12Be, for which
Doppler shift is corrected. A full-energy peak corresponding to the 2+ -+0+ transition is clearly seen at
2.1 MeV. Another peak at around 3.4 MeV is possibly the , rays associated with the breakup reaction,
12Be -+ 10Be*(2+ :3.368 MeV) +2n. Further analysesof the data are now in progress.
800

600
~

.-'<:

~

?c

400

~

0

u

200

1500

2000

2500
3000
E7 [keY]

3500

4000

Fig. 1. De-excitation "(-ray energy spectrum observedin the 1 H + 12 Be inelastic scattering. Doppler shift iscorrected for (see text) .

References
1) G. Kraus et al.: Phys. Rev. Lett. 73, 1773 (1994).
2) J. H. Kelley et al.: Phys. Rev. C 56, R1206 (1997).
3) M. A. Kennedy et al.: Phys. Rev. C 46, 1811 (1992).
4) 1. Hisanaga et al.: RIKEN Accel. Prog. Rep. 31, 162(1998).

67

RIKEN Accel. Prog. Rep. 31 (1998)

Coulomb Excitation of 11 Bet
T. Nakamura, T. Motobayashi, Y. Ando, T. Nishio, H. Sakurai, S. Shimoura,
T. Teranishi, Y. Yanagisawa, and M. Ishihara[NUCLEAR REACTION 11 Be + Pb, Coulomb excitation, Neutron halo]
The Coulomb excitation of a halo nucleus 11 Be to
its first bound excited state (E1: 1/2+ --+ 1/2-) has
been studied using a 64 MeV /u 11 Be radioactive beamincident on a 208Pb target. The electric dipole strength

Condensed from the article in Phys. Lett. B 394, 11 (1997)

68

deduced by a first-order perturbation analysis is ingood agreement with the result of previous life-timemeasurements of the 11 Be 1/2- state.

RIKEN Accel. Prog. Rep. 31 (1998)

Coulomb Dissociation of 12N
T. Minemura, T. Motobayashi, S. Shimoura, H. Murakami, Y. Ando, T. Nishio, Y. Yanagisawa,
M. Suzuki, H. Fujiwara, T. Kikuchi, T. Uchibori, Y. Iwata, H. Sakurai, Y. Watanabe,
K. 1. Hahn, T. Teranishi, M. Hirai, N. Aoi, T. Nakamura,
M. Ishihara, H. Utsunomiya, and K. Miki
[20Bpb(12N,l1C p)20BPb, Coulomb dissociation, Relative energy spectra]
The Coulomb breakup technique was employed todetermine the radiative width of excited levels in
12N and the direct proton-capture contribution in the
11C(p,,) 12 N reaction. This reaction is important in
the hot pp chain nuclear burningl) in hydrogen-richmassive objects. At a high-temperature and highdensity condition, this capture reaction becomes fasterthan the (3+ decay of 11C. However, this 11C(p,,) 12 N
reaction is difficult to study experimentally because
the life-time of 11C is too short (T 1/ 2 = 20.4 min) to
prepare it as target.
In the energy region of astrophysical interest, there
are two resonant states in 12N. The first one at the
p_11C center-of-mass energy Eern = 0.359 MeV corresponds to the J7r = 2+ excited state at Eex =0.960 MeV. The second one at Eern = 0.589 MeV canbe formed by s-wave proton capture, and corresponds
to the J7r = 2- state at Eex = 1.19 MeV which decays
to the ground state by an El transition. For the radiative width r l' of the 1.19 MeV state, Wiescher et al. 2)
suggest r l' = 2 me V using the mean value of the "(transition strength distribution in mass region aroundA = 12. With a model based on the generator coordinate method, Descouvemont and Baraffe3 ) predict amuch larger value r l' = 140 me V for the same level.
The related experiments have been performed at
RIKEN using the secondary beam line, RIPS. A
72.2 MeV /nudeon 12N radioactive beam was produced through fragmentation reactions of a primary
135 MeV /nudeon 14N beam. A 50 mg/cm 2 20Bpb target was bombarded by the secondary 12N beam, andthe breakup fragments, 11 C and proton, were detectedin coincidence after traveling through 4.4 m flightpath.
The energies and scattering angles of proton and 11 C
were measured. From these quantities, we can reconstruct the p_11C relative energy and scattering angle ofthe p_11C center-of-mass. The experimental relativeenergy spectra are shown in Fig. 1. The histogram (a)shows the yield measured with the 20Bpb target, and(b) shows the yield without the target which is consid-

ered as the background. The background-subtracted
net spectrum is shown in (c), where a broad bump isseen at around 0.5 MeV. This bump might contain thetwo peaks corresponding to the 2+ state (r < 20 ke V)
and the 2- state (r = 118 keV) , which overlap within the experimental energy resolution estimated to beabout 150 ke V presently. A more complete analysis of
the data including the evalution of the 12N -+ p +11 C*
process is under way.

200

]

150

o

()

100
50

o
~ 0.06~~ 0.04~ 0.02
-3...
0.00

-0.02

Fig.
1.
Relative energy spectra obtained for the
20Bpbe 2N,llC p)2oBpb reaction. The three histograms
correspond to the yields with (a) and without (b) the
20Bpb target, and the ,background subtracted net yield(c).

References
1) A. Jorissen and M. Arnould: Astron. Astrophys. 221,
116 (1989) .

2) M. Wiescher, J. Garres, S. Graff, L. Buchmann, and F.
K. Thielemann: Astrophys. J. 343, 352 (1989).
3) P. Descouvemont and 1. Baraffe: Nucl. Phys. A 514, 66(1990).

69

RIKEN Accel. Prog. Rep. 31 (1998)

Quadrupole Moment of 13 0
K. Matsuta, M. Tanigaki, K. Sato, T. Minamisono, M. Fukuda, Y. Nojiri, M. Mihara, S. Takeda,·1
T. Miyake, K. Minamisono, A. Morishita, T. Fukao, Y. Matsumoto, T. Ohtsubo,
S. Fukuda, S. Momota, K. Yoshida, A. Ozawa, T. Kobayashi, I. Tanihata,
G. F. Krebs,·2 J. R. Alonso,·2 and T. J. M. Symons· 2
NUCLEAR STRUCTURE, Nuclear magnetic resonance,[ Measured quadrupole moment of 13 0 ground state
The electric quadrupole (Q) moment of 13 0(/11" =3/2-, T1/2 = 8.6 ms) has been determined reliably
from the ,B-Nuclear Quadrupole Resonance (,B-NQR)
on 13,190 and Fourier Transformed NMR (FT-NMR)
on 17 0 in Ti0 2. The preliminary value of the Q moment reported previously1) was revised based on thepresent precise field gradient.
The electric quadrupole coupling constant eqQ/hof the 13 0 implanted in Ti0 2 was determined fromthe ,B-NQR on the polarized 13 0 provided by RIKEN
Ring Cyclotron and RIPS fragment separator, as wasreported previously. 1) The c axis of the (tetragonal)
Ti02 catcher was set parallel to the external magnetic
field, Ho = 8 kOe. From the observed NQR spectrum shown in Fig. 1 (essentially the same as Fig.
2 in Ref. 1), the coupling constant was obtained as(1-r7')leq'QI/2he 30 in Ti0 2) = 128(6) kHz by fittinga theoretical function to the peak at the higher frequency (peak 2). The peak at the lower frequency(peak 1) can not be analyzed due to the lack of resolution.

0 il ~ (cllHO)

13

~
0

0>0

<=

..c::

'"

2

b'
0

1

;>.

0

0

§
~

Ho=8kOe
H,=12Oe
FN=:t:151cHz

3

HI

;>.

f!

·1

cO.
0

20

40

eo

80

100

120

140

M(kHz)

Fig. 1. NQR spectrum for 13 0 in Ti02.

The eqQ/h and the asymmetry parameter ry for 17 0
in enriched Ti 17O 2 were re-measured using the pulsed
FT-NMR method without any dopant since the oldvalue was not reliable enough due to the Cr impurities used for the signal amplification. From the resonance frequencies as a function of the rotation angle,
leqQl/h(170 in Ti0 2) = 1512(4) kHz and ry = 0.831(7)were determined for substitutional 17 0.
We have studied the ,B-NQR on 19 0 in Ti02 using the 5-MV Van de Graaff accelerator at Osaka
.. 1
.. 2

70

Faculty of Engineering, Gunma University
LBL, Berkeley, U.S.A .

0.5

190 in 'ria2
C//BO(8kOe)

5

10

15

20

25

Vs (kHz)

Fig. 2. NQR spectrum for 19 0 in Ti02 .

Univ. As shown in NQR spectrum for cl 1Ho (Fig.
2), we found two different implantation sites. Combined with another spectrum for (llO) II Ho shown in
the inset, eqQ/h and ry were determined. From this ry,
the peak in Fig. 2 with small coupling frequency was
found to be the one from the substitutional site, andleqQllhe 90 in Ti0 2) = 208(17) kHz was obtained.
Therefore, the ratio of the Q moments for 17, 19 0 was
determined from the ratio of their coupling constants
to be IQ(190)IQ(170)1 = 0.138(ll). The coupling constant of the other implantation site was determined tobe (1-ry')leq'QI/2h(190 in Ti0 2) = 42.1(0.8) kHz. The
clear peak for 13 0 in Fig. 1 corresponds to this second
site, not the substitutional site which we previously
thought. Thus, the ratio of the Q moments is determined to be IQ(130)IQ(190)1 = 3.04(16). Here, we
have,
IQe 70)1 : IQe 90)1 : IQe 30)1
= 1: 0.138(11): 0.42(4),Using the known Q(170) = 26(3) mb, Q moments are
determined as
IQ( 19 0)1 = 3.6(5) mb, and IQe 30) 1= 11.0(1.6) mb.
The shell model value Q(130) = +16 mb calculated by
the OXBASH code using a harmonic oscillator radial
wave function is significantly larger than the present
value. Advanced theoretical investigation on a protonhalo effect, for example, is needed.
References
1) K. Matsuta et al.: RIKEN Accel. Prog. Rep. 29, 60(1995) .

RIKEN Accel. Prog. Rep. 31 (1998)

Coulomb Dissociation of I1C and I9C
T. Nakamura, N. Fukuda, T. Kobayashi, N. Aoi, M. Ishihara, H. Iwasaki, T. Kubo,
A. Mengoni, M. Notani, H. Otsu, H. Sakurai, S. Shimoura,
T. Teranishi, K. Yoneda, and Y. X. Watanabe[17,19C+ Pb, Coulomb dissociation, Neutron halo)

Neutron halo structure has been one of highlights in
the recent nuclear physics research. A neutron halo
structure has so far been established for 11 Li, 11, 14 Be,
and 17B. All of these nuclei possess the characteristic
nature of loosely-bound valence neutron(s). Recently,
the neutron rich carbon isotopes 17, 19 C draw attentions as neutron-halo candidates since their separationenergies are small (Sn(17C) = 729±18 keY, Sn(19C) =170±110 keY). Recent measurements on longitudinal
momentum distribution for the core fragment have infact suggested a halo structure for 19C and an ordinary
structure for 17C.1) However, the experimental difficulties have strongly limited their structure information
available for these nuclei. In particular, the groundstate total angular momentum and parity have not yet
been determined for these two nuclei. The determination of their ground-state spin is important since thecentrifugal barrier related to the nuclear spin may prevent the formation of the neutron halo. A Coulomb
dissociation reaction is suitable for probing the halo
structure since it is sensitive to the halo wave function
and thus can be used to determine the matter distribution and spin of the valence neutron. 2)
We have measured the Coulomb dissociation of
17,19C using the radioactive beam line RIPS at RIKEN
Ring Cyclotron Facility. The momentum vectors of

the two outgoing particles, 16C + neutron and 18C +neutron, have been measured in coincidence, respectively, for the reactions 17 C + Pb and 19 C + Pb at
67 MeV/nucleon to determine the Coulomb excitation energy spectrum. The 17 C and 19C ion beams
have been produced from the 22Ne primary beam at
110 MeV. The typical secondary beam intensities wereabout 30 kcps and 300 cps, respectively, for 17 C and19C. The time of flight for the beam ion was measured
with the two thin plastic scintillators that were placed
5.15 m apart. The position and direction of the beam
ion were measured with four sets of M ulti-Wire Proportional Counters (MWPC). The outgoing fragment
was measured by the magnetic spectrometer with two
sets of tracking drift chambers and by the plastic scintillator hodoscopes. The outgoing neutron was measured with the plastic scintillator hodoscopes placed ato degree. The experimental setup is essentially sameas that once used for the 11 Be Coulomb dissociation
experiment. 2) The analysis of the experimental data is
now in progress.
References
1) D. Bazin et al.: Phys. Rev. Lett. 74, 3569 (1995).
2) T. Nakamura et al.: Phys. Lett. B 331, 296 (1994).

71

RIKEN Accel. Prog. Rep. 31 (1998)

Measurements of the 18N Magnetic Moment andElectric Quadrupole Moment
H. Ogawa, K. Asahi , K. Sakai, A. Yoshimi, M. Tsuda, Y. Uchiyama, T . Suzuki, K. Suzuki, N. Kurokawa,*1
M. Adachi, H. Izumi, H. Ueno, T. Shimoda, S. Tanimoto, N. Takahashi, W.-D. Schmidt-Ott,
M. Schafer, S. Fukuda,*2 A. Yoshida, T. Kubo, H. Okuno, H. Sato, M. Notani,
N. Aoi, K. Yoneda, H. Iwasaki, N. Fukuda, M. Ishihara, and H. Miyatake[I8 N g .s .; ,6-NMR; measured magnetic moment, electric quadrupole moment]
We report on the measurement of the magnetic
moment and electric quadrupole moment of the 18N
ground state (J7r = 1-, TI/2 = 624 ms) 1) by meansof the ,6-ray detected nuclear magnetic resonance (,6NMR). The standard shell-model calculations lead toa predicted ground-state spin and parity2) of J7r = 2- ,while the experimental assignment is J7r = 1-.
The experiment was carried out using the RIKEN
Projectile-fragment Separator, RIPS. A spin-polarized
beam of 18N was obtained from the fragmentation of
22Ne projectiles at 110 A MeV on a carbon target,by selecting the emission angle and momentum. To
facilitate the measurement for such an isotope of low
production yield, we developed a new scheme, basedon an adiabatic rotation of the holding field , to determine the degree of polarization before the NMR was
observed. The experimental setup used is shown in
Fig. 1.

successfully performed to determine the electromagnetic moments, as shown in Figs. 2 and 3. The magnetic moment of the 18N ground state was determined
to be IJ.LI = 0.3279 ± 0.0017 J.LN and the quadrupole
coupling constant in Mg to be I~ I = 73.2 ± 1.8 kHz.
From the latter, the electric quadrupole moment of
18N was deduced as IQI = 12.1 ± 1.2 mb, by taking anelectric field gradient q for the N impurity in Mg from
Ref. 3. The comparisons of the above obtained J.L andQ values with theories will be presented elsewhere.

4.541---::::±:::--_ _ _ _ _ _--i

o

-.:

~ 4.5
:;
4 .48

4.46
200.0

202 .0

204.0

206.0

208 .0

210.0

212.0

frequency [kHz)Fig. 2. NMR Spectra obtained for the I8N implanted in
Pt at T = 30 K .
J)Olarized

lragme~'"

•••••

v___

......... coil+-+-~~v~'2!.~~zS;~........stopper

1.93,----,-----,-----r- - - , -----,

coil

o

1.91

~

Fig. 1. Experimental setup for the measurement of thefragment polarization by the method of magnetic fieldrotation. The setup includes two pairs of air-core coils,
respectively producing the vertical and horizontal components of a holding field Bo. The combined Bo field
is rotated by slowly varying the currents in these twopair coils, thus rotating the nuclear spin adiabaticallyby 180 0 •With this scheme, the optimization of the emission
angle and momentum for the maximum polarization
was made, eventually yielding a 18N polarization of
2.2 ± 0.7% (here the ,6-asymmetry factor A,B = -0.37
was assumed). Then, the ,6-NMR measurement was
*1
*2

72

Research Laboratory for Nuclear Reactors, Tokyo Instituteof Technology
The Energy Research Center , Wakasa Bay

~

1.9
1.89
1.88
1.87 L----'-_----'-_----'-_----'_---.J
65.0
70.0
75 .0
80.0
85.0
eqQ/h [kHz)Fig. 3. Result of the measurement of the electric
quadrupole coupling constant for the IBN implanted ina Mg cry stal. The up/down ratio of (3-ray intensities
is plotted as a function of eqQ / h.
References
1) W. Olness et al.: Nucl. Phys. A 373, 13 (1982).
2) F. C. Barker et al.: Aust. J. Phys. 37, 17 (1984).
3) T. Minamisono et al.: to be published in Phys. Lett. B.

RIKEN Accel. Prog. Rep . 31 (1998)

Measurements of Half Lives and Neutron Emission Probabilities of
the Neutron Drip Line Nuclei 19B, 22C, and 23N
K. Yoneda, N. Aoi, H. Iwasaki, H. Sakurai, H. Ogawa, T. Nakamura, W.-D. Schmidt-Ott, M. Schafer,
M. Notani, N. Fukuda, E. Ideguchi, T. Kishida, S. S. Yamamoto, and M. Ishihara[RADIOACTIVITY 19B,22C,23Nj Measured Tl/2' Delayed n emission probabilities]
For the past few decades, extensive experimental
studies of neutron-rich light nuclei have been performed. However, in the extremely neutron-rich region, some nuclei are still difficult to study experimentally, even concerning the measurement of their half
lives, because of their small production rate. Here, thefirst measurement of half lives and ,8-delayed neutron
emission probabilities of the neutron drip line nuclei
19B, 22C, and 23N is reported.
The experiment was carried out at RIPS. The nuclei 19B, 22C, and 23N were produced by projectile
fragmentation, using a 95 MeV/nucleon 40 Ar primarybeam with an average intensity of 60 pnA impinging on
a 666 mg/cm 2 Ta target. Each fragment was identified
on-line by measuring its time of flight and its energy
loss inside of a 0.5 mm thick silicon detector. The typical intensities of 19B, 22C, and 23N were 0.04, 0.003,
and 0.09 cps, respectively. The unstable nuclei wereseparately implanted into an active stopper, a 12 mm
thick plastic scintillator. After the implantation of a
nucleus with Z ~ 5, the primary beam was turned off
for 100 ms, a much larger period than the expected half
lives, during which the decay of nuclei was measured.
The stopper plastic scintillator was used for the detection of ,8 rays emitted from the implanted unstable
nuclei. A neutron detector array was placed aroundthe stopper to measure ,8-delayed neutrons in coincidence with ,8 rays. 1) The neutron detector consistedof 14 liquid scintillation counters (BC501A) covering
a solid angle of about 80% of 411". Neutrons and,rays were separated by a pulse shape analysis (Fig. 1).

The energy threshold for the neutrons was set to be 50
keVin electron equivalent energy, which corresponds
to about 400 keVin neutron energy. The efficiency obtained was 30%, determined by measuring ,B-delayed
neutrons from the 15B which has a known neutron
emission probability of 100%.2)
The decay curves obtained for the nuclei are shownin Fig. 2. The horizontal axis is the time interval between the implantation of one fragment and the detection of the ,B decay. The values of half lives werededuced from the least-squares fits to the data, assuming a functional form given by an exponential plus a
constant background. The preliminary results of thehalf lives are 3.3±0.2 ms for 19B, 9±3 ms for 22C, and14.5 ± 1.4 ms for 23N, with the quoted errors being ofstatistical origin only.

500

50

19

B

e

T 1/2=,...;.......... 100

3.3 ± O.2ms

!l
~

;:l
0

e

I[)

e

I[)

C':i

C\1

..........

..........
(JJ

(JJ

50

u

N

(JJ

(JJ

(JJ

23

22c

1:: 10

1::;:l

;:l
0

0

u

U 100

50

10
2

L.LU..lJL.U..LLJL.UL.U.Jl..I..J.Ul.J.......

10 20 30 40

Time [ms]

20

40

60

Time [ms]Fig. 2. Preliminary decay curves of 19B, 22C, and 23N.
Solid lines represent best-fit curves and dashed lines dothe adopted constant backgrounds.

The values of the neutron emission probabilities were
determined from the ratio of the number of detected
neutrons to that of ,8 rays, considering the efficiency ofthe neutron detector array. Tentatively deduced neutron emission probabilities of 19B, 22C, and 23N are
125 ± 32%, 99 ± 39%, and 80 ± 21 %, respectively. Here,both statistical and systematic errors of the n-, separation are taken into account.
References
Fig. 1. Separation of the neutrons from , rays achievedby using 15B. The vertical axis is the total light output
and the horizontal axis is the amount of light being
integrated in the first 60 ns.

1) V. Kunze et al. : Nucl. Instrum. Methods Phys. Res. A
361, 263 (1995).
2) R. Harkewicz et al.: Phys. Rev. C 44, 2365 (1991).

73

RIKEN Accel. Prog. Rep. 31 (1998)

Lifetime Measurement of 31, 32 Ne
M. Notani, N. Aoi, N. Fukuda, E. Ideguchi, M. Ishihara, H. Iwasaki, H. Ogawa,
T. Kubo, S. M. Lukyanov, T. Nakamura, Yu. E. Penionzhkevich, H. Sakurai,
T. Teranishi, Y. X. Watanabe, K. Yoneda, and A. Yoshida
NUCLEAR REACTIONS: 181Ta(40 Ar,X); E(40 Ar) = 95A MeV,
Half-life measurement of 31 ,32 Ne
Beta-decay half-lives of two very neutron-rich nuclei
31 ,32Ne have been measured for the first time. The twonuclei are the heaviest stable neon isotopes observed sofar. 1,2)
The secondary beams of neutron-rich nuclei were
produced by the projectile-like fragmentation of a
95A MeV 40Ar 17 + beam with a mean intensity of
40.3 pnA. From the preliminary investigation on target dependence of fragment yields,3,4) we used a
607 mg/cm2 thick 181Ta target. Very neutron-rich nuclei in 9 ~ Z ~ 11 were separated by means of the
RIKEN Projectile Fragment Separator (RIPS)5) witha 221 mg/cm 2 aluminium energy-degrader at the momentum dispersive focal plane, Fl.
The identification of the fragments was carried out
by means of measurement of time-of-flight (TOF) andenergy deposit (~E). At the final focal point F3 , all thedetectors were mounted: a 1 mm thick plastic scintillation counter (PL) , two 0.5 mm surface barrier typesilicon detectors, and three lithium drift type silicondetectors with thickness of 1, 3 and 1 mm, respectively;
plus a 2 mm thick plastic scintillation veto counter.
The TOF of fragments between the production target
and F3 was obtained from the PL timing and RF signalof the cyclotron. The ~E of heavy ion was obtained
from the first two silicon detectors.
This system of detectors was served as both thefragment identification and ,6-decay measurement. We
measured the time interval from the PL timing to the,6-ray timing. The last three Li-drift type silicon detectors allowed us to perform the {3-ray detection. Whenthe fragments of interest reached the detectors, we suspended the primary beam for 100 ms in order to measure the time intervals and avoid the pile-up of fragments in the meantime. In order to stop the neutronrich nuclei, 32Ne and 31 Ne, at the 4th Si detector, thesecondary beam energy was reduced with a 3.2 mm
aluminium degrader located between 2nd and 3rd silicon detectors.
Figure 1 shows the (3-decay curve of 31,32Ne and theirdaughter nuclei. We have achieved the ,6-ray detection efficiency 75% from the sum of time-interval histograms divided by the net number of identified ions.
At this experiment , the half-lives of other neutronrich isotopes 27,29F , 29 ,30 Ne and 31 ,32 ,33Na were reexamined. The measured results of these half-lives areshown in Table 1.

74

1

()
Q)

()
Q)

rIl

rIl

S

co

S

10

co

T 1/2 =
3.5±O.9ms
10

\
\

\
\

Time (ms)Time (ms)Fig. 1. Time-interval histogram for 31,32 Ne. The solid line
is a likelihood fit with sum of two exponential functions.
The dashed and dotted lines are drawn as parent anddaughter components, respectively.

Table 1. Experimental half-lives in milliseconds.
Nuclei
(A,Z)
27F
29F
29Ne
30Ne
3INe
32Ne
3INa
32Na
33Na

This work
4.9 ± 0.2
2.6 ± 0.4
15.6 ± 0.5
5.8 ± 0.2
3.4 ± 0.8
3.5 ± 0.919 ± 411.5 ± 0.8
8.5 ± 0.4

T I/2 [ms]Tarasov 6 )5.3 ± 0.9
2.4 ± 0.8
15 ± 37±2

18 ± 2

Table'97 7)

200 ± 10017.0 ± 0.4
13.2 ± 0.4
8.2 ± 0.4

References
1) D. Guillemaud-Mueller et al.: Phys. Rev. C 41 , 937(1990).
2) H. Sakurai et al.: Phys. Lett. C 54, R2802 (1996) .
3) Y. Doki: JAERI-M 94-028, p. 70; Master thesis, Tokyo
University (1994).
4) H. Iwasaki et al.: RIKEN Accel. Prog. Rep. 31, 76(1998) .
5) T. Kubo et al. : Nucl. Instrum. Methods Phys. Res. B
70, 309 (1992).
6) O. Tarasov et al. : Phys. Lett. B 409, 64 (1997).
7) G. Audi et al.: Nucl. Phys. A 624, 1 (1997).

RIKEN Accel. Prog. Rep. 31 (1998)

Coulomb Excitation of N rvZrv28
Y. Yanagisawa, T. Motobayashi, S. Shimoura, Y. Ando, H. Fujiwara, I. Hisanaga, H. Iwasaki,
Y. Iwata, H. Murakami, T. Minemura, T. Nakamura, T. Nishio, M. Notani, H. Sakurai,
S. Takeuchi, T. Teranishi, Y. X. Watanabe, and M. Ishihara[208Pb(56Ni,56Ni ,)208Pb, Coulomb excitaion, Deduced B(E2) ]Recently, Coulomb excitation at several tens MeV /uhas been studied using unstable beam. 1 ,2) From thespectroscopic point of view, the electromagnetic excitations are properties useful in studying basic structures of the nuclei. We studied Coulomb excitation of
the N rv Z rv 28 nucleus such as 56Ni and 56Fe, using
an unstable beam provided by the RIPS at Riken Ring
Cyclotron Facility.
A 208Pb target of 285 mg/cm 2 thickness was set in
the vacuum at the focal point of the RIPS, and was
bombarded by a 56Ni beam with 800 particles s-l intensity. Scattered 56Ni nuclei were detected by a ~E­
E silicon detector telescope placed at 35 cm from thetarget after passing through a 50 /-Lm thick mylar window. 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 the 2+state in coincidence with the scattered
56Ni particles.
Fifty-six NaI(TI) scintillators were placed aroundthe target to detect the, rays. Each scintillator crystal is of 6 cm square rod with 12 cm in length, 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. Lead blocks with 20 cm thickness shielded
the NaI(TI) detectors from the spurious, rays due tonuclear reaction in silicon detector.
Figure 1 shows the ,-ray spectrum for the 56Ni +208 Pb inelastic scattering after the doppler shift correction. As clearly seen in the spectrum, a single photopeak at the 2.7 MeV corresponding to the 2+ -7 0+transition has been observed. The total full-energy efficiency was calculated by a simulation code GEANT.

100
60
60
40
20

Illi!l!

. II I I IIIlillIIII IjIjIlillill I I I I~I I III j

.I

0
1500

.

IHt III! tl

t t ft t

f

2000

2500

3000

3500

Energy [keY]

Fig. 1. Doppler-corrected spectrum for ,-ray energy emitted from the inelastic scattering 56Ni + 208Pb measured
by NaI(TI) counters.

The excitation cross section was obtained to be 212 ±13 mb. An experimental deformation parameter f3c
was extracted by comparing the predicted cross section, which was calculated by a coupled channel code
ECIS88, with the experimental one. Since this parameter f3c is directly related to B (E2), The parameterf3c is related to B(E2) by f3c=47rVB(E2)/3ZR2e, aB(E2) value for the 56Ni 2+ excitation was obtainable.
The result, B(E2 : 0+ -7 2+) = 580±70 e 2fm\ agrees
with the value deduced from an analysis of the 56Ni +P inelastic scattering3 ) within experimental errors.
References
1) T. Motobayashi et al.: Phys. Lett. B 346, 9 (1995).
2) T. Nakamura et al.: Phys. Lett. B 394, 11 (1997).
3) G . Kraus et al.: Phys. Rev. Lett. B 264, 1773 (1994).

75

RIKEN Accel. Prog. Rep. 31 (1998)

Production Cross Sections of Projectile-like Fragmentsin the 40 Ar + 181Ta Reaction at 94A MeV
H. Iwasaki, N. Aoi, N. Fukuda, E. Ideguchi, M. Ishihara, T. Kubo, T. Nakamura, M. Notani, H. Ogawa,
H. Sakurai, T. Teranishi, Y. Watanabe, Y. X. Watanabe, and K. Yoneda

1~UCLEAR ~,EACTIONS: 18 1Ta(40 Ar,X), E(40 Ar) = 94A MeV; Measured[ YIelds of the Isotopes of B, C, N, 0, F, Ne, Na, Mg, Al and Si

The projectile fragmentation has been one of themain methods for the production of radioactive beams.
It was reported that the yields of the neutron-rich isotopes by a 44A Me V 48Ca beam have a strong dependence on the N / Z ratio of the target; the 181Ta target
provides larger yields than 9Be and 64Ni targets in theextremely neutron-rich region, if one uses the energyloss-equivalent production targets. 1) However, the prediction of the fragment yields by INTENSITY code,2)
which is based on production cross sections given by anempirical formula EPAX,3) does not include such target dependence and overestimates yields. 4) Therefore
we have investigated the fragment yields in the 40 Ar +181Ta reaction, and we found the best-fit parameter(U)for this specific reaction under the EPAX formalism.
A 94A Me V 40 Ar beam accelerated by the RIKEN
ring cyclotron was incident upon a 623mg/cm 2 181Ta
target. The reaction products were analyzed by the
RIPS spectrometer. 5) The magnetic rigidity of RIPS
was varied in steps in the range 3.02 ('..) 4.52 Tm to cover
2.8 :S A/Z :S 4.2 nuclei. A 2.0 mm thick plastic scintillation counter (PL) and three 0.5 mm thick surfacebarrier silicon detectors were set at the first achromatic focus of the RIPS (F2). Particles were identified
event-by-event by measuring the time-of-flight (TOF)
and the energy loss (.6.E). The TOF of each fragment
over 21.3 m flight path between the target position andF2 was determined from the difference of timing signals between RF signal of the cyclotron and the PL.
The .6.E was independently determined using three silicon detectors. The measured values of TOF and .6.E's
were combined to identify the proton number( Z) andthe mass number(A). By using the transmission calculated by the INTENSITY, we deduced the production cross sections from measured yields for the isotopes: 19B, 17- 20 C, 20- 23 N, 19- 24 0, 21- 29 F, 24- 32 Ne,
27- 33 Na, 30- 35 Mg, 33-36 AI, and 36Si, as shown in Fig.
1. In analysis, we chose the B p setting for each nucleus
to have the best transmission.
To describes the yield distribution as the functionsof A and Z of the fragments, the following empiricalformula was used in the EPAX,a(A, Z) = Y(A) N exp( - R I Zp - Z

U
I

).

The first term Y(A) gives the mass yield and the second term describes the Z distribution of the cross sections around the most probable charge (Zp) in eachisobar. The parameter U, which specifies the width76

Present Experiment
EPAX- - Modified EPAX
:r;

100

':0
~
Q

:3

10- 3

0

Q)

rt.l
OJ
OJ

0

'"

CJ

10- 6

20

25

30

35

Mass Number. A

Fig. 1. Production cross sections in the 40 Ar + 181Ta reaction. The dotted line and solid line are calculated byusing EPAX 3 ) (U = 1.5) and modified EPAX (U = 1.6),
respecti vely.

and shape of the Z distribution of cross sections, isfixed by 1.5 for the neutron-rich side in the EPAX.3)
However, it was reported in the 40 Ar + 9Be reaction
at 93.6A MeV that the parameter U = 1.7 gives a better description of the fragment yields. 6) In the present
experiment, we have found that the parameter U = 1.6
describes the yields in the 40 Ar + 181 Ta reaction best,
as shown in Fig. 1. The present result as well as theresult from Ref. 6 shows that the parameters in EPAX
depends on the beam and target combination. It may
also indicate the beam energy dependence of a(A,Z).
Further accumulation of production cross sections under the various projectile-target combinations at various beam energies is necessary.
References
1) D. Guillemaud-Mueller et al.: Phys. Rev. C 41, 937(1990) .
2) J. A. Winger, B. M. Sherrill, and D. J . Morrissey: NucL
lnstrum. Methods Phys. Res . B 70, 380 (1992).
3) K. Summer et al.: Phys. Rev. C 42, 2546 (1990).
4) M. Notani et al.: RIKEN Accel. Prog. Rep. 30, 48(1997).
5) T. Kubo et al.: Nucl. Instrum. Methods Phys. Res. B
70, 309 (1992).
6) Y. Doki: JAERI-M 94-028, p. 70; Master Thesis, Tokyo
University (1994).

RIKEN Accel. Prog. Rep. 31 (1998)

Polarized 129Xe Solid for Polarizing Unstable Nuclei
K. Sakai, Y. Mizumura, Y. Uchiyama, T. Suzuki, K. Suzuki, M. Tsuda, A. Yoshimi, H. Ogawa,
M. Adachi, K. Asahi, H. Sato, H. Okuno, T. Kubo, A. Yoshida, M. Ishihara,
K. Yoneda, M. Notani, S. Fukuda, * and H. Izumi[Nuclear magnetic moment, 129Xe solid stopper]
Measurements of nuclear moments provide useful information in the st udy of microscopic structure of nuclei far from stability.1-4) In such experiments, spin polarization of the objective nuclei plays a key role. We
have proposed a new method to produce the spin polarization, which comprises an implantation of unstable
nuclei into a highly polarized stopper and subsequenttransfer of the host nuclear polarization to unstable
nuclei through dipole-dipole interaction. As a polarized stopper, we are developing a polarized 129Xe solid
for which a large spin polarization as well as a longrelaxation time can be attained. 5)
The 129Xe nuclear spin can be polarized by spin exchange with an optically polarized Rb atom. A cylindrical glass cell, 4 cm long and 2 cm in diameter, isfilled with an enriched (79.2%) 129Xe gas of a partial pressure PXe, a N2 gas of 100 Torr, and a small
amount of Rb vapor. The cell has a rectangular part(8 x 20 x 2 mm3 ) at the bottom, which thermally contacts with the surface of a liquids nitrogen vessel. The
inner surface of the cell is coated with SurfaSi1 6 ) inorder to reduce the spin relaxation rate r w( = l/Tw)
due to the collision ofaXe atom with the cell wall.
The cell is illuminated by a circularly polarized lightfrom two 15- W AIGaAs diode lasers. We made several
cells with the surface coating, among which some exhibited relaxation times as long as Tw ~ 24 min. The
maximum 129Xe gas polarizations (Pgas ) thus obtained
were P gas = 11% at 800 Torr and P gas = 5.6% at 2400
Torr. 7 ) They were then cooled down to about 80 K ina liquid nitrogen.
Within 10 min after the cooling was started, about
1/3 (80 mg) of the 129Xe gas condensed into a solid.
Typical polarization measured for such a solid was

Psolid = 1%, amounting to about 1/4 of the gas-phasepolarization, measured before freezing. A possible explanation of this relatively large loss of polarization
during the freezing process is the relaxation in gas
phase because of the relatively long condensing time.
The relaxation time T1 of the polarized solid was measured under 10 to 60 mT. The longest value T1 '" 25
min was observed at the highest field strength 60 mT.
According to literature,5-8) T1 '" 25 min implies thatthe solid was at around 120 K. T1 '" 160 min would
be achieved by lowering the temperature of the solid
to about 77 K.
Our experimental result for a polarized solid 129Xe
suggested that the problems of large polarization loss
during freezing and of short T1 in solid would be solved
by cooling to a lower temperature and in a shorter
time. In order to realize these, we made a slight change
in the setup improving the heat contact between thecell and the liquid nitrogen vessel. As a result, almost the entire part of 2400 Torr ('" 240 mg) of 129Xe
gas condensed within 5 min after liquid nitrogen waspoured into the vessel. We expect that the polarization
loss and T1 will be much improved in this condition.
The measurements are in progress.

References
1) H. Okuno et al.: Phys. Lett. B 354, 41 (1995).
2) H. Izumi et al.: Phys. Lett. B 336, 51 (1995).
3) H. Deno et al.: Phys. Rev. C 53, 2142 (1996).
4) K. Asahi et al.: Nucl. Phys. A 588, 135c (1995) .
5) M. Gatzke et al.: Phys. Rev. Lett. 10, 690 (1993).
6) X. Zeng et al.: Phys. Lett. 96A, 191 (1983).
7) H. Sato et al.: RIKEN Accel. Prog. Rep. 30, 64 (1997).
8) C. D. Cates et al.: Phys. Rev. Lett. 65, 2591 (1990).

The Energy Research Center, Wakasa Bay

77

RIKEN Accel. Prog. Rep. 31 (1998)

Coulomb Dissociation of 8B at 254 MeV lu
N. Iwasa, K. Siimmerer,*l F. Boue,*l G. Surowka,*l P. Senger,*l P. Koczon,*l E. Schwab,*l H. Geissel,*lM. Hellstrom,*l F. Laue,*l A. Surowiec,*l T. Baumann,*l W. Schwab,*l A. Ozawa, E. Grosse,*lA. Forster,*2 H. Oeschler,*2 C. Sturm,*2 F. Uhlig,*2 A. Wagner,*2 B. Kohlmeyer,*3
J. Speer,*3 B. Blank,*4 C. Marchand,*4 M. S. Pravikoff,*4 S. Czajkowski,*4
R. Kulessa,*5 W. Walus,*5 T. Motobayashi, T. Teranishi, and M. Gai*6

The 7Be(P,r)8B reaction at low energy is of crucial importance for predicting the high-energy solarneutrino ft.ux relevant to the "solar neutrino problem",defined as a serious discrepancy between the measured
and predicted neutrino ft.uxes'!)
Recently, Motobayashi et al. succeeded to measure
the 7Be(P,r)8B cross section at EC.M. = 600-1700 keVfrom the Coulomb dissociation of 8B into 7Be andproton at E(8B) = 46.5 MeV /u. 2) The result demonstrated that the Coulomb dissociation process is analternative method for studying the 7Be(p,r)8B reaction. However, for more precise measurement of the
7Be(P,r)8B cross section, experimental information on
E2 and M1 admixtures to the dominant E1 amplitudeis desired.
We have studied the Coulomb dissociation processat E(8B) = 254 MeV lu to extract information on theM1 admixture experimentally, and to obtain the (P,r)
cross section at low center-of-mass energies down to the
100 ke V region with a higher statistical accuracy. A
radioactive 8B beam provided by the fragment separator at GSI impinged on an enriched 208Pb target with athickness of 200 mg/cm 2 . The reaction products, 7Be
and proton, were analyzed by the Kaon Spectrometer (KaoS)3) which has a large momentum acceptance(tlp I p ~ 200%). For track reconstruction of the twocharged particles, 7Be and proton, before entering the
KaoS magnet, two sets of two-dimensional positionsensitive device were installed at approximately 14 and31 cm downstream of the target. Each device consisted of x- and y-projection silicon micro-strip detectors. Each micro-strip detector had a thickness of 300
11m, an active area of 56 x 56 mm 2, and a strip pitchof 0.1 mm. This configuration enabled us to measureemission angles with an accuracy of 0.9 mrad, as wellas vertex points of the two charged particles. By using the vertex information, a large amount of background events produced in the matters other than thetarget was eliminated. The particle's momenta wereanalyzed by trajectory reconstruction in the KaoS by
using position information from the strip detectors and
*1

*2

*3

*4

*5
*6

78

GSI, Germany
Technische Hochschule Darmstadt, Germany
Universtiit Marburg, Germany
CEN Bordeaux, France
Jagellonian University, Poland
University of Connecticut, U.S.A.

two multi-wire proportional chambers (MWPC; onefor proton and the other for 7Be) placed at approximately the focal plane of the KaoS. Thirty plastic
scintillators were placed just behind the MWPC's for
producing trigger conditions to the data acquisition
system.
The p- 7Be coincidence yields are plotted in Fig. 1 asa function of p-7Be relative energy. The solid (dashed)histogram represents the E1 +Ml (pure El) yield estimated by Monte Carlo simulations. The continuumEl and resonant-Ml direct-capture cross sections measured by Filippone et a1. 4 ) and Vaughn et a1. 5) wereused in the simulations. The cross sections are renormalized with the resonant 7Li( d,p )8Li cross section,
157 ± 10 mb. The shape and magnitude of the experimental energy dependence are fairly well-described by
the simulated results. Because of low background condition, the 7Be(P,r)8B cross sections at 150- 2950 keV
are expected to be determinable from this experiment.
Further analysis is in progress.

200 ,-----------------------------,

5>

Q)

~

§ .100 L

'"C

CD

':;"

oo -

_ _. __ -.L _ _ _ _ _ _ _ .1-- ____ _

1

2

3

Erel [MeV]Fig. 1. The p- 7 Be coincidence events plotted as a function of relative energy shown by filled circles. The solid(dashed) histogram represents the E1+M1 (E1) amplitudes predicted by Monte Carlo simulations.

References
1) J. N. Bahcall and M. H. Pinsonneault: Rev. Mod. Phys.
64, 885 (1992).
2) T. Motobayashi et al.: Phys. Rev. Lett. 70, 2680 (1994);
N. lwasa et al.: J. Phys. Soc. Jpn. 65, 1256 (1996).
3) P. Senger et al.: Nuc!. lnstrum. Methods Phys. Res. A
327, 393 (1993).
4) B. W. Filippone et al.: Phys. Rev. C 28, 2222 (1983).
5) F. J. Vaughn et al.: Phys. Rev. C 2, 1657 (1970).

RIKEN Accel. Prog. Rep. 31 (1998)

Measurement of Interaction Cross Sections
for Light Neutron Rich Nuclei
A. Ozawa, K. Suemmerer,*1 o. Bochkarev,*2 L. Chulkov,*2 D. Cortina,*1 H. Geissel,*1 M. Hellsrom,*1
M. Ivanov,*3 R. Janik,*3 K. Kimura, T. Kobayashi, A. Korsheninnikov, G. Muenzenberg,*1 F. Nickel,*1
A. Ogloblin,*2 M. Pfutzner,*1 V. Pribora,·2 C. Scheidenberger,·1 H. Simon,·1 B. Sitar,·3
T. Suzuki, P. Strmen,·3 1. Tanihata, M. Winkler,·1 and K. Yoshida
NUCLEAR REACTIONS; 40Ar+Be, E", 1 A GeV; Secondary beams;[ OJ 7 , 19 B, 12- 20 C, 14- 23 N, 16- 24 0 + C)e

The recent development of radioactive nuclear
beams provides new measurements of the radii of unstable nuclei at the relativistic energy.1,2) It is important to extend the measurement of interaction crosssections (01 's) and the determination of radii, so that
we can view the isotope, isospin, and energy dependences of the radii over a wide region in the nuclear
chart. The above systematics over a wide region makes
it possible to search for the new nuclei having ananomalous structure, such as a halo and/or skin.
We have measured the OI'S for light neutron richnuclei, so called p-sd shell region, by using FRagment Separator (FRS) facility at GSI. Figure 1 shows
the schematic view of the FRS and our experimental
setup. The setup was almost identical to the previous
experiment,2) except for using Time Projection Chambers (TPC 's) developed at Comenius University in Slovak Republic,3) instead of the conventional MultiWire
Proportional Chambers (MWPC's).

. __

l

c_oo_ ~}.
J--\ Q #0-11-0",0 -."..oAr primary beam

F2

I

~
~

Plastic scintiUaton

I

CollimatorI

TPC

The secondary beams of radioactive isotopes 17,19B,
12- 20 C, 14- 23N, and 16- 24 0 were produced through*1*3

the projectile fragmentation of an 40 Ar primary beam
(approximately 1 A GeV) accelerated by the heavy-ion
synchrotron (SIS) at GSI. The secondary beams produced in a Be target located at the entrance of FRS
were separated by their rigidities at F1, then guided
to reaction targets located at F2. Individual nucleus
was identified by its Time Of Flight (TOF) (between
Fl and F2) and dE/dx. The aI 's were measured bymeans of a transmission method with carbon (C) reaction targets at a mean energy of around 950 A MeV.
Two kinds of reaction targets different in thickness(one ",5.5 g/cm 2 and another ",11 g/cm2) were usedin order to estimate systematical errors for the measurements.
Downstream of the reaction targets, non-interacted
nuclei were guided through F3 to F4. These nuclei wereidentified again by their TOF (between F2 and F4) anddE/dx. Now that we measured the non-interacted nuclei at F4, we need to know the transmission of the
non-interacted nuclei from F2 to F4. The transmission depends on the position and direction of the nuclei
at F2. Thus, in order to measure them at F2 eventby-event, we put two TPC's upstream of the reaction
targets, that served X and Y positions and the directions for the nuclei. We also put an additional reaction target (a ",2.3 g/cm2 thick C) at F4 and measured
dE/dx after the target. By this setup we have simultaneously measured the charge changing cross sections
at F4, which can give the maximum size of the charge
matter radii. 4)
Analysis is now in progress.

MUSIC

Fig. 1. Experimental setup at FRS in GS1.

*2

1

References
1) 1. Tanihata et al.: Phys. Rev. Lett. 55, 2676 (1985).
2) T. Suzuki et al.: Phys. Rev. Lett. 75, 3241 (1995).
3) T. Baumann et al.: Acta Physica Universitatis Comenianae 37, 3 (1996).
4) O. Bochkarev et al. : Z. Rhys. A, in press.

GSI, Darmstadt, Germany
Kurchatov Institute, Moskow, Russia
Comenius Univ., Bratislava, Slovak Republic792. Atomic and Solid-State Physics

RIKEN Accel. Prog. Rep. 31 (1998)

Electron Capture in Collisions of H+ Ions with S Atoms
and Its Reverse Process below keY-Energies
M. Kimura, T. Watanabe, H. Sato, 1. Shimamura, J.-P. Gu,* G. Hirsch,* and R. J. Buenker*
The distribution of ionic states of atomic elements
provides important information for diagnoses of theionic structure in the interstellar gas, solar corona,and planetary nebulae. 1) Also, it is essential in designing and operating controlled thermonuclear fusion
devices based on the confined hot plasma. 2) Standard
models which describe forbidden lines of neutral carbon and sulfur underestimate the intensities of the observed [C I] and [S I] lines, and it has been proposedthat inclusion in the models of charge transfer reactions with atomic hydrogen may account some partsof the discrepancies,3) i.e.,(i) ground atom:
H+ + S(3 p ) ~ H + S+(2 P ) + 0.198 eV(la)~ H + s+ (2D) + 1.397 eV(lb)(ii) excited atom:
H+ + S(lD) ~ H + s+ep) + 1.343 eV~ H + S+(2D) + 2,542 eV(iii) capture by S+ ions:
S+(4S) + H ~ S(3 p ) + H+ - 3.238 eV(2a)ElectroD capture iD

u+ + S('P) collisioDS
S +c' P) ronaalloa)~ 0 OoO .8·~·i
o
0 ioO

10,16

.....

. . ..

"
0

0

..

.~

0

f

U

S+('D) rormation

10'"

0.001

0.01

0.1

10

E (keV)

Fig. 1. Electron capture cross sections for the H+ + Sep)
collisions. Solid circles represent the S+ eD) formationand open circles are for the S+ ep) formation.

(2b)

(3)

Butler and Dalgarno4) estimated the capture rate
coefficient at a temperature of 1 x 10 4 K and foundthat the process is slow with a rate coefficient of theorder of less than 10- 15 cm 3/s. To the best of ourknowledge, there is no rigorous experimental attempt
to study the capture process of this system at low tointermediate energies, and capture cross sections areneeded urgently.
In present, the ab initio potential curves and nonadiabatic coupling matrix elements for the HS+ system
are obtained from multireference single- and doubleexcitation configuration interaction (MRD-CI) calculations employing a relatively large basis set. A semiclassical molecular orbital expansion method with astraight-line trajectory of the incident ion was employed to study the collision dynamics below 10 keY.
A set of first-order coupled equations was solved numerically to obtain scattering amplitudes for transitions . The molecular states included in the dynamical
calculations are the three sets of states as shown in
Fig. 1: (i) triplets; [H + S+(2P)] (1 3E+, 2 3II) and[H + S+(2D)] (2 3E-, 1 3II) states for electron capture from the initial ground states [H+ + Sep)] (33E-, 3 3II), (ii) singlets; [H + S+ (2P)] (1 1E+, 2 III)and [H + S+(2D)] (1 Ill) states for electron capture
from the initial excited [H+ + SeD)] (2 1 E+, 3 1 II)states, and (iii) the molecular states included for the
rH + S+(4S)]. c?~lision system are: [H + S+i4 S)] (13E-) for the InItial, and [H+ + Sep)] (3 3E ) state
for charge transfer, and [H + S+eD)] (2 3E-) statefor excitation.
Theoretische Chemie, Universitaet Wuppertal, Wuppertal,
Germany

The spin-averaged electron capture cross section
from the ground state S(3P) atoms by H+ impact is
illustrated in Fig. 1, as an example. A few interesting
features are seen, and they include: (i) both electron
capture cross sections to the [H + S+ (2P)] and [H +S+(2D)] states increase rapidly as the collision energy
increases from 10 eV, with a slightly larger magnitude
for the [H + S+(2P)] formation, (ii) the cross sections
to these two states show slight out-of-phase oscillatory
structures at intermediate energies from 30 eV to 2 ke V
region, indicating rather strong interference between
these two channels, (iii) above 3 keY, the electron capture to [H + S+(2D)] becomes dominant in magnitude
over that of [H + S+ep)), even though the asymptotic energy defect is larger. This is because the E - E
radial coupling between the initial and 2 3E- state becomes more effective in this energy domain, resulting
in a larger flux population in the E state, and (iv) the[H + S+(2P)] state formation begins to show a slightdecrease beyond E = 2 ke V because of the less effective II - II radial coupling being the sole driving force
in this energy region. Between 0.2 and 1.0 keY, bothcross sections are similar in magnitude and in energy
dependence, causing a strong mixing between the twochannels, and their magnitudes are found to exceed thevalue of 10- 16 cm 2.,
References
1) J. B. Kingdon and G. J. Ferland: Astrophys. J. Supp!.
Ser. 106, 205 (1996).
2) J. W. Gallagher, B. H. Bransden, and R. K. Janev: J.
Phys. Chern'. Ref. Data 12, 873 (1983).
3) D. Pequignot, S. M. V. Aldrovani, and G. Stasinska:
Astron. Astrophys. 58,411 (1978).
4) S. E. Butler and A. Dalgarno: Astron. Astrophys. 85,
144 (1980).
81

RIKEN Aeeei. Prog. Rep. 31 (1998)

Theoretical Attempt for Double Ionization of Helium
by Energetic Charged-Particle Impact
Y. Kawabata,* K. Hino, N. Miyashita,* S. Watanabe, and M. Matsuzawa[Double ionization of helium]
We report the present status of the investigation underway in our group on the double ionization processof a helium atom due to impact of energetic chargedparticles such as proton, anti-proton and other various
multiply-charged ions. A great deal of attention was
paid about a decade ago on the experimental evidences
for significant roles of the electron correlation effect ofhelium during the dynamic processes, resulting marked
differences between cross sections by proton impact
and those by anti-proton impact. While there were anumber of follow-up studies from both theoretical andexperimental sides, the deeper understandings are stillrequired. Most of theoretical works rely just on perturbation approximations based on the independentparticle models for double-continuum states of helium
and are thus incapable of providing quantitative understandings of the processes. (Although only the socalled forced impulse approximation well reproduces
the relative values of the observed quantities, its predictions for the absolute values considerably underestimate the experimental results and its theoreticalstructure seems vague and complicated.) Aside froma theoretical framework of how to deal with the collision dynamics, the way of incorporating the substantial
electron correlation interactions with the target wavefunctions of double continuum dominates the qualitiesof theory for the problem.
Our basic strategy is the full employment of the hyperspherical coordinate method for incorporating thethings mentioned above effectively into theory. It
has resulted a great success in reproducing the measured cross sections of the electron-emission spectra
due to autoionization from lower-lying doubly-excitedstates of helium caused by proton impact. 1) Here,the continuum basis functions introduced in the closecoupling (CC) equations for the time-propagation ofcollision dynamics were the accurate eigenfunctions of
the helium autoionizing states, and they are discretizedsuitably based on the wave-packet description. For
the double ionization processes, however, such frameworks encounter numerical difficulties that the enormous number of basis functions would be needed toexpress the double continuum states accurately, which
are composed of infinite numbers of open channels,
up to the relatively higher-energy region of emitted

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

82

electrons. Thus the resulting CC equations seem intractable.
In order to remedy these problems, the following manipulations will be adopted. First of all, instead of using as basis functions the exact wave functions of helium for continuum states, as done in theabove-mentioned autoionization spectra, an advantage
is made of a more tractable set of discrete eigenfunctions of a model Hamiltonian, which provides the hyperspherical adiabatic potentials with the infinite barriers artificially placed at a relatively large distance.
The discrete variable representation2 ) is suitable forconstructing the wave functions of the model Hamiltonian. These wavefunctions remain well-correlated. It
is also expected that they serve to reduce, to some extent, the number of basis functions to be incorporated
into the CC equations, since only a single wave function is assigned to each grid of energy spectra, differingmuch from the real wave functions adopted before.
However, neither the basis functions fabricated here
nor the obtained coefficient vectors of the CC equations
satisfy the correct scattering boundary conditions forionizing states. This is a price for the present manipulation. In order to satisfy the conditions properly, we
enforce the operation of projecting on the coefficient
vectors a complete set consisting of wave functions ofa real helium rather than a model helium, which already satisfies the suitable boundary conditions. This
procedure is equivalent to transform the coefficient vectors by the over lap matrices between wavefunctionsof real Hamiltonian and those of the model one, although the matrices are not always unitary. The abinitio calculations of double ionization cross sectionsof helium induced by the impact of charged-particles
are in progress along this direction.
One of the authors (K. H.) acknowledges the financial support by Matsuo Foundation to the present
work.
References
1) T. Morishita et al.: Phys. Rev. A 53, 2345 (1996), andother references therein.
2) A. S. Dickinson and P. R. Certain: J. Chern. Phys. 49,
4209 (1968).

RIKEN Accel. Prog. Rep. 31 (1998)

Superexcited States of the Hydrogen Molecule
S. Uramoto, H. Sato, and I. Shimamura
Doubly excited states of molecules play an important role in various phenomena such as photoionization, photo dissociation, and dissociative attachment
and vibrational excitation in electron collisions withmolecular ions. In other words, these processes canoccur through doubly excited states, which often leads
to fine structures in the cross sections as a function ofenergy. Many calculations and experiments have been
performed for doubly excited Rydberg series of superexcited states of the hydrogen molecule H 2 . Thesestates lie above the ionization threshold, and the Rydberg series converging to the 2pau (2p1T'u) state of Hi,
which is the second (third) ionization threshold of H 2 ,are called Q1 (Q2) series. Unfortunately, the calculations of the higher members of the Q1 and Q2 series
are scarce because of the computational complexity.
The present work is devoted to such calculations in the
Born-Oppenheimer approximation based on the Feshbach projection operator.
As for the molecular orbitals for these calculationsof doubly excited H 2 , we need both low-lying and highlying states of Hi. Bound-state calculations are normally performed by using the Slater-type or Gaussiantype orbitals centered on each of the two nuclei as basis functions. For accurate calculations of high-lying
states, however, these basis functions are physicallyinappropriate and computationally inconvenient, causing a linear dependence if many of them are to be included in the basis set. To remedy this difficulty wehave used a set of orthogonal functions involving Sonine polynomials and centered not only on the nuclear
positions but also on the center of mass of the nuclei.
In other words, we have used three-center functions.
The calculated potential energy curves 1sag and6da9 of Ht are compared quite favorably with the exact numerical results in Fig. 1. Figure 2 shows somedoubly excited Q2 states 1 ~t (i) (i = 1 - 5) of H2
calculated by using nag, nau , n1T'i, n1T';, n8i, n8;(n = 1 - 10) orbitals. The lowest of these states wascalculated by Guberman 1 ) by using a less elaborate
trial function than the present work, but the agreementwith the present result is reasonable. Calculations ofhigher states are not found in the literature.

Is IJ g exact
present
6d IJ g exact

present--•------A' 'A . . . . . . . . . . _______ . . _______ -A- ___ ___ _

o

2

3

4

5

INTERNUCEAR DISTANCE R (a.u.)

Fig. 1. Potential energy curves, including the nuclear
repulsion term, of the IsO'9 and 6dO' 9 states of Ht.

ILg+ (Q2)
Gubennan 1) l~g +(1)O.

present'"':',e" O.

>0
c::
~
tIl

<>

B
6.

----....-

l~g+(l)0l~g\2)

6.

l~t(3)

0l~g\4)v

l~g+(5)

<>

...l

<

§
tIl

f-<

0

0..

INTERNUCLEAR DISTANCE R(a.u.)

Fig. 2. Calculated potential energy curves of the fivelowest members of the doubly excited superexcited Q2states 1 Et (i) (i = 1- 5) of H 2 . The result for the lowest
state is compared with Guberman's results. 1)

References
1) S. L. Guberman: J. Chern. Phys. 78, 1404 (1983).

83

RIKEN Accel. Prog. Rep. 31 (1998)

Theoretical Study of Electron Scattering from CH 2 F 2 Molecules
T. Nishimura
Here we report our theoretical work on the vibrationally elastic scattering of electrons from CH 2 F 2molecules (C 2v point group). This is an extension of
our previous work on the electron-molecule collisionsystem. I) No elaborate study for this system has been
published so far. In a practical point of view, the dataof the e+CH 2 F 2 system are in great demand becauseof the application to the plasma processing in the semiconductor industry.
The present calculation is based on the fixed-nuclei
approximation. In order to properly consider themolecular symmetry, the wavefunction of scatteredelectron F is expanded in terms of the symmetryadapted angular basis functions Xl as follows:

F(r) = ~r

L ftv (r) Xl(f),

(1)

lv

where r denotes the position vector of the incident electron. The index lJ stands for indices collectively specifying an irreducible representation (lR) and those distinguishing the degenerated members of the same land
IR. The interaction between an electron and a target
molecule is represented by a local potential, which isconstituted of the electrostatic, electron exchange andcorrelation-polarization terms. All of the terms depend
only on the electron density of the target molecule. In
a manner similar to Eq. (1), the interaction potential
V is expanded asformula which involves in · the rotational state of thetarget molecule.
The present calculation of the target wavefunction was made at an equilibrium geometry. In order to obtain the electron density of molecule, weused the molecular orbital code GAMESS2) in the selfconsistent-field approximation. In the expansion of Eq.
(2), we retained the terms up to A = 40. The coupled equations (3) were solved with inclusion of partial
waves up to l = 20. The DeS was calculated in theregion of the collision energies from 5 to 30 eV .
Figure 1 shows the DeS at 20 eVasa representative result. The agreement between the theory and theexperiment 3 ) is generally good. It should be noted thatthe DCS has a very sharp peak in the forward direction, which makes it difficult to extrapolate the measured DCSs toward the forward direction. The present
DCS would be helpful in compensating the uncertaintyof the experimental data. In order to obtain the relevant integral cross sections (leSs) theoretically, however, the rotational-state population should be taken
into account, especially in the case of a polar moleculedue to the strong dependence of the forward scattering caused by the dipole interaction on the IeS. The
calculation of the leSs is under way.
100
~

-:

..
V)

V(r) =

L V,\J.L (r) Xf(r).

(2)

,\J.L

E
~

Then, the radial part f (r) in Eq. (1) satisfies a set of
coupled differential equations:

10

.~
~

rJJ
til
til

0

~2 _ l(l +2 1) + k 2 } Jlv (r )

{ dr
= 2

r

L (llJIVll'lJ') Jl'v,(r),

(3)

l'v'

U
]
~
~

:5
0.1
50

where

(llJIVll'lJ') =J

df Xr*(r) V

xv' (r).

(4)

By solving Eq. (3) with an appropriate boundary
condition, we obtain the scattering matrix. Since
differential cross section (DCS) represented by thepartial-wave expansion converges very slowly for a polar molecule, the Born-closure formula I ) is employed tosum over the higher partial waves. The contribution
from these partial waves to the resulting DCS is dominated by the electron-dipole interaction. The dipole
interaction can be calculated by means of the first Born

84

100

150

Scattering Angle ( deg. )Fig. 1. Differential cross section (in 10- 16 cm 2 sr- 1 ) forthe elastic scattering of electrons from CH 2 F 2 at thecollision energy of 20 eV. The present calculation (fullcurve) is compared with the experiment by Masai (filled
circules with error bars). 3)

References
1) Y. Okamoto et al.: J. Phys. B 26, 745 (1993).
2) M. W. Schmidt et al.: J. Compo Chern. 14, 1347 (1993) .
3) T. Masai: Master thesis (Sophia Univ. 1997), p. 44.

RIKEN Accel. Prog. Rep. 31 (1998)

Fluorination Effects in Electron Scatterings fromCH 4 , CH 3 F 1 , CH 2 F 2 , CH 1 F 3 , and CF 4
H. Tanaka,* T. Masai,* M. Kimura, T. Nishimura, and 1. Shimamura
Due to basic interests of their own fundamental natures of molecular electronic structure and scattering
process as well as vast applications in plasma chemistry and material sciences, a study on the elastic andinelastic processes of electron scattering from methaneand fluoromethanes (CH 4 , CH 3F I , CH 2 F 2 , CH I F 3,
and CF 4 ) has become increasingly important in recent
years, and thus has attracted a great deal of interests. I)
Comparative studies of electronic structure and scattering process from CH 4 to CF 4 by replacing a H atom
in a methane molecule with a F atom would provide
much deeper insight for basics of atomic and molecularphysics in hydrocarbons and their dynamical interaction mechanisms. Furthermore, a set of cross section
data for electron scattering from partially fluorinatedmethane gases are urgently needed in plasma processing, material sciences and earth sciences since thesemolecules, which have a shorter-life time than that of
the CF 4 in the atmosphere, are considered to be "environmental acceptable, next generation plasma processing gases". 2) Although there have been earlier studies for these systems by using the electron energy-loss
techniques to identify electronic states 3) as well as bytheoretical approaches for CH 4 and CF 4 . 4) However,no complete study based on electron scattering elastic
differential cross sections (DCS 's), important objective
for a detailed and high-precision study, has been carried out to date to the best of our knowledge. Therefore, as a series of studies , we have initiated the present
joint experimental and theoretical investigation for any
signature of the fluorination effect in these molecules
on DCS 's in the energy range from 0.7 to 100 eV, which
may possess wider potentials for further understandingof interactions and for possible application for molecular structure analysis.
Figure 1 presents an example of elastic DCS's observed for all molecules at 30 eV. We tentatively classify the molecules treated here into two groups for thelater discussion, (i) one for (CH 4 and CF 4 ); non-polar
molecules, and (ii) another for (CH3FI ' CH 2 F 2 , andCH 1 F 3); polar molecules.
Salient features in the present results are summarized here: (a) At 1.5 eV, DCS's for the class (i) show
an increasing trend at small angles below 70° , while
those for the class (ii) , i.e., all partially F -substit ut ed(polar) methanes, rapidly grow to result in strong forward peaks: typical characteristics of the long-range
interaction, (b) At larger angles above 100°, these twoclasses of molecules show again a deviation in DCS's
causing less strong backward scattering for the class(i), (c) At 30 eV , the sharp forward peaking in DCS 's
at small angle scattering below 50° is very similar to
all molecules, indicating less effective dipole-effect at
this energy, (d) Within each class of molecules, DCS's

30

60
90
120
Scattering angle (deg)

ISO

180

Fig. 1. Experimental DCS's from CH 4 , CH 3 F 1 , CH 2 F 2 ,CH 1 F 3 , and CF 4 molecules at the electron impact energy of 30 eV.

are similar with respect to scattering angles at all energies, and all DCS's become more resembled (except fora structure near at 60°, as seen below) at higher energies above 20 eV, (e) The conspicuous shoulder begins
to appear around 60°- 65° as each hydrogen is replaced
by a fluorine atom, and the magnitude of the DCS at
this angle is proportional to the number of F atom ina molecule: the fluorination effect, (f) At higher energies above a few 10 eV, the strength of the DCS
show more complicated features and do not appear todepend strongly on molecular natures. Particularly,
it shows much complicated trend for small-scattering« 50°) and large-scattering (> 100°) angles except formuch higher energies where the magnitude of the DCS
is in the order of the number of F atom, and (g) At
above 30 eV, more undulations can be seen at small angles , especially for those molecuies which contain more
F atoms, suggesting the atomic (fluoride) effect due tothe multiple scattering.
In summary, we have carried out a joint experimental and theoretical study of electron scattering fromCH 4 , CH 3 F 1 , CH 2 F 2 , CH 1 F 3, and CF 4 molecules. We
have found a prominent structure around 60° at intermediate scattering energies, and this structure grows
as the number of F atom in a molecule increases. The
origin of this structure is a combination of a mixing ofmany partial waves and of a resonance due to unoccupied molecular orbitals.
References
1) L. G. Christophorou, J. K. Olthoff, and M. V. V. S.
Rao: J. Phys. Chern. Ref. Data. 25 , 1341 (1996).
2) L. G. Christophorou, J. K. Olthoff, and M. V. V. S.
Rao: J . Phys. Chern. Ref. Data. 26, 1 (1997).
3) M. B. Robin: in Higher Excited States of Polyatomic
Molecules (Academic Press , New York and London,1974), p. 178 .
4) W. M. Huo: Phys. Rev. A 38, 3303 (1988); J. Phys . B
22 , 1225 (1989).

Department of Physics , Sophia University

85

RIKEN Accel. Prog. Rep. 31 (1998)

The Coupling of Electron Thermalization and Electron Attachment
in CCI4 / Ar and CCI4 /Ne Mixtures t
K. Kowari, K. Leung,* and B. D. Shizgal*
We study the time evolution of the electron nonequilibrium distribution function from some initial distribution under the influence of elastic and inelastic collisions of electrons with the ambient gases, and electron
attachment to some electronegative gas. We consider
a mixture of either Ar or Ne and CC1 4 so that thecollision processes to be considered are elastic electroninert gas and electron-CC14 collisions, vibrationally inelastic electron-CC14 collisions, and electron attachment to CC14 . The inert gas moderators are chosen so
as to have an example of a gas (Ar) with a RamsauerTownsend minimum and a second moderator (Ne) for
which the momentum transfer cross section is nearly
constant with energy.
The time dependent electron energy distributionfunction is obtained from the Boltzmann equation,and the energy relaxation times are determined. The
steady average energy of the electrons can be above
the ambient temperature of the moderators because of
the effect of attachment heating. This effect was discussed by Shizgal 1 ) except that inelastic collsions were
neglected in that study.
Kowari and Shizga1 2 ) extended this previous work to
include vibrationally inelastic collisions as well. However, the portion of the attachment cross section below
0.1 eV used in Ref. 2 does not coincide with the actual
cross section for the system studied. The calculations
are repeated in the present paper for the correct crosssection,3) and the results are reinterpreted. Both crosssections are shown in Fig. 1. We use the attachment
cross section above 0.1 eV given by Hayashi. 4) The
time dependence of the average electron energy for thetwo attachment cross sections is shown in Fig. 2.
Warman and Sauer 5 ) reported an experimental technique to determine the energy relaxation rate coefficients and the relaxation times in pure inert gases andother moderators by following the reaction kinetics ofelectron attachment to CC14 . In this paper, we study
the validity of the analysis used by Warman and Sauer
to extract relaxation times from the electron kinetics
assosiated with attachment. We compare the relaxation times extracted from the electron kinetics withthose determined directly from the relaxation of theaverage energy. We also compare with the very recent
measurements by Shimamori and Sunagawa. 6 )Condensed from the article in J. Chern. Phys. 108, 1587
(1998)
Department of Chemistry, University of British Columbia,
Vancouver, Canada

86

600
500
400
~

(\I

300

tl

200
100
0
0.00

0.05

0.10

0.15

E(eV)

Fig. 1. Electron attachment cross section, e-CCI4: (a)cross section used by Kowari and Shizgal, (b) cross section used in the present work.

24
20

~ 16

~

12
8
4

300

600

900

1200 1500 1800

t (ns)

Fig. 2. Time variation of the average energy, CCl4 in
Argon with all collision processes included, XCCl4 =5 X 10- 6 . (a) Results for the attachment cross sectionused by Kowari and Shizgal, Fig. 1(a). (b) Results forthe attachment cross section used in the present work,
Fig. l(b).

References
1) B. Shizgal: J. Phys. B 24, 2909 (1991).
2) K. Kowari and B. Shizgal: Chern. Phys. Lett. 260, 365(1996).
.
3) A. Chutjian and S. H. Alajajian: Phys. Rev. A 31 , 2885
(1985).
4) M. Hayashi: in Swarm Studies and Inelastic Electron
Molecule Collisions, edited by L. C. Pitchford, B. V.
Mckoy, A. Chutjian, and S. Trajmar (Springer-Verlag,
New York, 1987), p. 167; (private communication).
5) J. M. Warman and M. C. Sauer, Jr.: J. Chern. Phys.
62 , 1971 (1975).
6) H. Shimamori and T. Sunagawa: Chern. Phys. Lett.
261, 334 (1997).

RIKEN Accel. Prog. Rep. 31 (1998)

Resonances in Ps- System
A. Igarashi and 1. Shimamura
The positronium negative ion Ps- (e- e- e+) is a special system where three particles with the same mass
are interacting via Coulomb forces. It is also an intermediate three body system between the atomic limit
H- and the molecular limit Ht. Even in H-, someof the resonance states, where two electrons are excited simultaneously, exhibit a spectrum similar to therotational-vibrational spectra of molecules. Therefore,
it would be quite interesting to see the resonance structures in Ps -. However, many resonances are still to be
calculated for the higher partial waves.
For the resonances in the Ps - system, continuous
efforts have been made by Ho and Bhatia 1} with thecomplex rotation method for high-lying resonances associated with the Ps(N :S 6) thresholds for the total
angular momentum L :S 2. References to the published results on the resonances in Ps - can be foundin the recent review by Ho.2)
We have calculated the resonance parameters of Psassociated with the Ps(N = 2,3) thresholds for partial
waves L :S 5. We have employed the hypersphericalclose-coupling method for the scattering calculation of
e- + Ps.
To specify the channels by which resonances are supported, we label them N(K, T)A 25+1 LIT after Ref. 3.
Here we show in Table 1 just the resonance parameterfor the lowest N = 3, (K, T)A resonances in each symmetry to compare them with the results in the complex rotation method; the agreement is generally good.
Some of the resonances are found new in the present
work. From Table 1, we see that resonance energies
with the same (K, T)A become shallower for larger L
and that those of the same (K, T =I- O)A and L but
different parities are almost degenerate.
In the 3(2,0)+ rotor series, there is a resonance ofthe 3 HO symmetry, which is absent from H- reflecting the shell structure of the atom. This additionalrotor state manifest itself because Ps - is an intermediate system between H- and Ht. The 1De 3(0,0)+
shape resonance calculated by the complex rotation
method was not reproduced in the present calculation. The existence of this resonance seems to be subtle
as is expected from the hyperspherical adiabatic potential curve, since its width is quite large and since it

Table 1. Energy E and widths r (in a.u.) of resonances associated with the Ps(N = 3} threshold in
Ps -. The shape resonances are distinguished from the
Feshbach resonances by inspecting the adiabatic hyperspherical potential curves, and underlined in the table.
a[b] = a X 1O b •Present
Label

Complex rotationr"E

2S+1L TI

E

r

lse

-3.5338[-2]-3.4868[-2}-3.3911[-2]-3.2473[-2]-3.0673[-2]-2.8527[-2]7.6[-5]6.1[-5}2.4[-5]8.5[-5}8.2[-5]5.6[-6]-3.5341[-2]-3.4871[-2]-3.3914[-2]7.5[-5]6.06[-5]
2.36[-5}-2.9368[-2]-2.9212[-2]-2.8906[-2}-2.8380[-2]-2.8046[-2]2.1[-7]
1.5[-6]
2.9[-6]
2.7[-5]4.4[-7]-2.9365[-2]-2.9215[-2]-2.8907[-2]1.[-5]
1.5[-6]4.2[-6]-3.1621[-2] 2.2[-4]-3.1626[-2] " 1.8[-4}-3.0410[-2] 1.3[-4]-3.0434[-2] 7.3[-5]-2.8696[-2] 4.0[-5]-2.8599[-2] 1.1[-5]-3.1622[-2}-3.1631[-2]-3.0411[-2]-3.0441[.:2)

2.21[-4]
1.79[-4]
1.32[-4]
7.2[-5](2,0)+
3po
IDe
3Fo
Ice

3Ho

(2,0)3se

lpo
3De
IFo

3Ce

(1,1)+
lpo
3pe
3De
IDo
IFo

3Fe

(1,1)3po

lpe
IDe
3Do

-2.8182[-2]-2.8201[-2]-2.7951[-2]-2.7947[-2]4.5[-6]8.2[-9]9.4[-7)
7.1[-7)-2.7949[-2)<1.50[-6]~2. 7394[-2]-2.7452[-2]

3.5[-4]3.2[-4]-2.7400[-2]-2.7485[-2]

3.2[-4]3.10[-4]-2.7741[-2]-2.720[-2)

7.0[-6)5.4[-4J

4.2[-5]-2.7725 [-2J
4.60[-4)-2.725[-2]-2.618[-2) " 2.04[-3)(0,2)+
IDe
3Do(0,0)+
Ise
3po
IDe

is located rather above the potential maximum.
ReferencesI} Y. K. Ho and A. K. Bhatia: Phys. Rev. A 50, 2155
(1994).
2} Y. K. Ho: Chin. J. Phys. (Taipei) 35, 97 {1997}.
3} C. D. Lin: Adv. At. Mol. Phys. 22, 77 (1986).

87

RIKEN Accel. Prog. Rep. 31 (1998)

Auger Transition Rates for Metastable Statesof the Antiprotonic Helium He+p
V. 1. Korobov and I. Shimamura
The recently measured time spectra of decay products after stopping of the antiprotons (15) in helium
have clearly shown delayed components, and have revealed the existence of extremely long-lived 15; about
3% of the stopped 15 lived as long as a few microseconds,
to be compared with a lifetime of some picoseconds forthe most of 15. 1 ) These long-lived 15 states have been
observed both in 4He and in 3He,2) but not in any
other materials hitherto studied, and are considered
to be due to a mechanism 3 ) similar to that for longlived kaons and pions in helium already known frombubble-chamber experiments in the sixties. 4)
The scenario in the independent-particle picture is
the following. Most of the 15 that stopped in heliumin the process He + 15 -+ He+p + e- occupy highly
excited orbitals in He+p with the principal quantum
numbers n around 40. These 15 cascade down to
the lower and lower orbitals by emission of an Auger
electron, by radiative transitions, and by energy andangular-momentum transfer in collisions of He+p with
ambient He atoms, thus eventually decaying into theintra-atomic encounter with the helium nucleus either
in a low-n state or in a high-n, s-state.
The long-lived 15 are considered to be those thatare captured into high n, nearly circular states, forwhich both radiative and Auger transitions are slow.
Accurate radiative rates were calculated previously,5)and were found to be of the order of microseconds for
25 < n < 50. Thus, the Auger rates are crucial in distinguishing between long-lived and short-lived 15 and in
determining the fraction of the former among all the
stopped p. The Auger rates are also indispensable forthe study of the whole cascade process.
In the present work the rates of Auger transitions ofantiprotonic helium 4He+p and 3He+p were calculated

88

by using a variational scattering method with an elaborate three-body trial function. The shift of the energy
levels of these systems due to the coupling with Augerdecay channels was also obtained from this calculation.
Thus, an improvement was made over the previously
calculated nonrelativistic energies. Together with therelativistic corrections calculated elsewhere,6) the theoretical transition wavelength between the states (n, l)= (37,34) and (38,33) of 4He+p (where l is the azimuthal quantum number), for example, was significantly improved to be 713.593 nm, which agrees wellwith the experimental value 713.578 ± 0.006 nm. The
calculated Auger lifetime of the level (38, 33) turned
out to be 3.2 ps, which should be compared with thevalue 4.1 ± 0.2 ps deduced from the measured line
broadening. Auger rates were calculated also using
Fermi's golden-rule formula with a regular Coulomb
function having no phase shift for the Auger electron.
The results agree fairly well with the accurate variational results.
Further details are reported elsewhere.7)
References
1) M. Iwasaki et al.: Phys. Rev. Lett. 67, 1246 (1991) .
2) T. Yamazaki et al.: Nature 361, 238 (1993).
3) G. T. Condo: Phys. Lett. 9, 65 (1964).
4) J. G. Fetkovich and E. G. Pewitt: Phys. Rev. Lett. 11,
290 (1963); M. M. Block et al.: Phys. Rev. Lett. 11,
301 (1963); M. M. Block et al.: Phys. Rev. 140, B 143(1965); J. G. Fetkovich et al.: Phys. Rev. D 2, 1803(1970).
5) I. Shimamura: Phys. Rev. A 46, 3776 (1992).
6) V. I. Korobov and D. Bakalov: Phys. Rev. Lett. 79,
3379 (1997).
7) V. I. Korobov and I. Shimamura: Phys. Rev. A 56, 4587
(1997).

RIKEN Accel. Prog. Rep. 31 (1998)

Fine and Quadrupole Structures of the Weakly Bound
Systems [(dtIL)lldee] and [(ddIL)lldee]
D. Bakalov,*l K. Bakalova,*2 V. Korobov,*3 H. J. Monkhorst,*4 and 1. Shimamura
The study of the muonic molecules dtp and ddp is
not only a central problem for the physics of muon catalyzed fusion but also a challenge to the theory of fewbody problems, since it allows a very precise experimental verification for the theoretical predictions. 1,2) Apoint of particular interest is the anomalously weakly
excited bound states of dtp and ddp with orbital angular momentum J jJ, = 1 and vibrational excitation
quantum number v jJ, = 1. These systems are formed
inside of larger six-body bound systems in the resonant
reactions dp + D2 -+ [(ddp) 11 dee] * and tp + D2 -+[(dtp)l1dee]* , in which the energy released is transferred to a rotational-vibrational excitation of the sixbody systems.
The six-body system [(ddp) l1 dee]* can be considered as an excited st ate of the diatomic molecule D M,
similar to the DT , in which a hypothetic point-likeheavy nucleus M of the mass equal to the total massof ddp is replaced by an ion (ddp) t1 ' Accordingly, theenergy levels E [(ddjJ,)lldeej- of the six-body system canbe represented in the form:
E [(ddjJ, )lldeej-= E (ddjJ, )ll + E ( DM)Jrv r + tlE.

(1)Here, E(ddjJ,)l1 is the energy level of the isolated 3-bodysystem (ddp)l1 , E ( DM)Jr vr is the energy of the corresponding excited state of the hydrogenlike molecule
DM , and tlE is a "finite size" correction term due tothe interaction of the constituents of ddp with the particles in D M other than M. The argument henceforth
may be easily carried over to [( dtp) 11 dee] *.
The complicated structure of the energy levels of
E[(ddjJ,) l1 dee )- is due to the fine and hyperfine splittings of the Coulomb level E(ddjJ,) 11 ,3) to the rotationalvibrational excitation spectrum of D M, and to thequadrupole splitting of the third term in Eq. (1), i.e.,
the finite size correction tlE. 4 - 6 )In the present work we have considered these threecontributions simultaneously for the first time, coupling all relevant angular momenta in a proper way.
We are basically following the approach developed ear-

*1

*2
*3

*4

lier in Ref. 4, but we also take advantage of the precise numerical results of Refs. 5 and 6 for the matrix
elements of the perturbation Hamiltonian. We havefound that the "quadrupole splitting" of the energy
levels of the six-body complexes E[(ddjJ,)lldee)Jrv r andE[ (dtjJ, )llde ejJr vr has the same order of magnitude as
the fine splitting of E(ddjJ,)ll and E(dtjJ,) 11 , as was foundpreviously,4-6) and should certainly be taken into account in an appropriate way, when interpreting the experimental data on the resonant formation of muonic
molecules.
The quadrupole corrections preserve the generalform of the hyperfine structures of (dtp) 11 and (ddp) 11 ,but disperse its components quite significantly. For instance, the three hyperfine states of (dtp)l1 with thetotal spin F of tp equal to 0, the total spin S of dtp
equal to 1, and the total angular momentum J a of dtp
equal to 0, 1, and 2 lie within less than 0.2 meV, while
the quadrupole interactions disperse them to nearly 3.5
meV; similar dispersions occur for the other hyperfine
levels too. As a result, formation rates shall be muchsmoother functions of temperature with much less pronounced resonant peaks than originally predicted.
Further details will be reported elsewhere. 7)
References
1) L. I. Ponomarev: Contemp. Phys. 31, 219 (1991).
2) A. Scrinzi, P. Kammel, J. Zmeskal, W. H. Breunlich,J. Marton, M. P. Faifman, L. I. Ponomarev, and T. A.
Strizh: Phys. Rev. A 47, 4691 (1993).
3) G. Aissing, D. Bakalov, and H. J. Monkhorst: Phys.
Rev. A 42 , 116 (1990).
4) D. Bakalov and V. S. Melezhik: JINR Communication,
P4-81-835 , Dubna, 1981 (unpublished).
5) M. R. Harston, I. Shimamura, and M. Kamimura: Phys.
Rev. A 45, 94 (1992).
6) M. R . Harston, S. Hara, Y. Kino, I. Shimamura, H. Sato,and M. Kamimura: Phys. Rev. A 56, 2685 (1997).
7) D. Bakalov, K. Bakalova, V. Korobov, H. J. Monkhorst,
and I. Shimamura: Phys. Rev. A 57, No.4 (1998), inpress.

Institute for Nuclear Research and Nuclear Energy, Sofia,
Bulgaria
Solar-Terrestrial Influences Laboratory, Sofia, Bulgaria
Joint Institute for Nuclear Research, Dubna, Russia
QTP, University of Florida, Gainesville, U.S.A.

89

RIKEN Accel. Prog. Rep. 31 (1998)

State-Selective Differential Cross Sections of Electron Capturein 10 MeV Ar 8 +-He Collisions
T. Kambara, Y. Nakai, T. M. Kojima, V. Mergel, H. Schmidt-Bocking, and M. Kimura
Dynamical processes have been studied for the
single-electron capture in collisions of 10 MeV Ar 8 +ions with He atoms:
Ar8 +(ls22 s 22p 6) + He(ls2)--+ Ar 7 + (ls22s22 p6 n l) + He+,(1)

through a state-selective measurement of differential
cross sections. The projectile Ar 8 + energy corresponds
to a velocity of 3.17 atomic unit (au). An Ar8 + ion
has a neon-like electronic configuration where K and
L shells are filled, and hence the electron can be captured to n = 3 or a higher orbital. The final-state
selective differential cross section is related to the transition amplitude, and its measurement is useful for detailed discussion of the collision process. However, only
few measurements have been reported for the collisions
between highly-charged heavy ions at energies higher
than hundreds of keY lu because the projectile scattering angles in these collisions are so small that theirmeasurements are extremely difficult. In the present
experiment, we have measured, instead of the projectile scattering angle, all the momentum components of
the recoil He+ ions applying the COLd Target Recoil
Ion Momentum Spectroscopy (COLTRIMS)1,2) in coincidence with the projectile which captures one electron. From the momentum analyses we have obtained(1) the kinetic energy gain which corresponds to thefinal state of the captured electron, and (2) differential
cross sections for these final states as a function of thetransverse recoil-ion momentum which corresponds tothe scattering angle.
The experimental setup of the COLTRIMS at the
RILAC was described previously.3)
The resolution of the recoil-ion momentum wasabout 0.2 au in all the directions, which corresponds toa resolution of 17 eV in the binding energy of the captured electron, and of 0.9 microradian in the scattering
angle.
The final states of the captured electron in Ar 7 + (nl)were clearly separated to the n = 3 state and the higher
excited states from the longitudinal momentum of therecoil ions. The capture to the n = 4 state was observed as a shoulder on the n = 5 state which was separated with Gaussian fittings. The electron capture
predominantly occurs into the n = 5 excited state.

90

Figure 1 shows the differential cross section of singleelectron capture to the n = 3 - 5 states. The experimental results of the differential cross sections are compared with calculations of the close-coupling approximation based on a molecular representation. 4 ) The experimental results are normalized with a common multiplication factor, so that the total yield summed overn = 3 - 5 states and integrated over the transverse
momentum up to 4 au is equal to the corresponding
theoretical value. The theoretical calculations agree
reasonably well with the experimental results.

...-..

C\J

o

~

o

1
234
Transverse Momentum (au)Fig. 1. Differential cross section of one-electron captureby 10 MeV Ar 8 + ions into different final states with theprincipal quantum numbers n = 3 - 5. Symbols denotethe experimental results and lines are the calculation
results.

References
1) T. Kambara: Butsuri 52, 18 (1997). (in Japanese)
2) J. Ullrich, R. Moshammer, R. Dorner, O. Jagutzki, V.
Mergel, H. Schmidt-Backing, and L. Spielberger: J.
Phys. B: At. Mol. Opt. Phys. 30, 2917 (1997).
3) T. Kambara, Y. Awaya, Y. Kanai, T. M. Kojima, Y.
Nakai, R. Dorner, V. Mergel, H. W . Schmidt-Baking,
M. Jager, and B. D. DePaola: RIKEN Accel. Prog. Rep.
30, 75 (1997).
4) M. Kimura and R. E. Olson: Phys. Rev. A 31, 489(1985).

RIKEN Accel. Prog. Rep. 31 (1998)

Beam Foil Spectra of Highly Charged Neon Ions
in Visible Region
K. Ishii, S. Kawae, T. Nakano, K. Ando, H. Oyama, and T. Kambara
Beam-foil spectra of highly charged Ne ions at theenergy of 0.4-1.0 MeV /amu were recorded in the region between 200 and 700 nm. Photons emitted fromthe Ne ion after its passage through a thin carbon
foil were dispersed by a monochromator and detectedby a liquid-nitrogen cooled CCD detector covering the
wavelength range of about 80 nm. The comparison of
the spectra recorded at two different energies has provided the charge state identification of the individual
lines.
Most of the intense lines are classified as transitionsof high n, f levels in Ne V to Ne X, based on the calculation of the hydrogenic term energies, the wavelengths and the transition probabilities for the Rydberg transitions. 1 ,2)The lines between 370 and 390 nm were classified as
1s2 2s7f-1s 2 2s8f transitions in Be-like Ne VII. It was
found that the transitions were split into f-components
by the perturbation of the nearby lying doubly excited
2pnf configuration to the 2s8f. 3 ,4)In the present work of spectral line intensity decay
measurement, we take a full advantage of the multichannel capability of the CCD detector. The decay
data for all the lines in the region between 210 and
290 nm were simultaneously recorded at forty-five different positions along the beam from the foil. The firstten positions were increased by 0.10 mm step size andthe second ten by 0.20 mm. Thereafter, the step size
was increased on a semi-Iogalithmic scale over a total
distance of 324 mm. The majority of the lines show
a multi-exponential decay characteristic of heavy cascading effects that result from the yrast transitions.
In Fig. 1, typical decay curves are displayed, where
the intensity is normalized to unity · at its maximum.
The lines numbered "a" through "f" reach to the maximum just after the foil position and decay in multiexponential nature. On the other hand, the lines numbered "gl" , "g2" and "h" show somewhat different decay mode. They reach slowly to their maximum anddecay in a single exponential feature. The designations attached with the label "a-h" are all for Be-like
Ne VII, except the Ne VIII 8-10. Plausible assign-

19~~~~==-=~~---=----=----~~~~
8
7

0.1

9

8

...--

f( (254.82nm))o23Flight lime(ns)45Fig. 1. Intensity decay curves of the lines around 250 nm
plotted on a semi-Iogalithmic scale. The distance fromthe foil position is converted to the flight time of the ionfrom the foil. The intsnsity for each line is normalized
to unity at its maximum. All the lines except that
denoted by Ne VIII are Be-like Ne VII.

ments were given based on the atomic structure calculation by including the perturbing configurations as
many as possible. 5 ) It is worthwhile to note that thelines which show single exponential decay feature are
due to the transitions of mutiply excited states, andtheir upper states lie slightly above the first ionization
limit.
References
1) H. A. Bethe and E. E. Salpeter: in Quantum Theory ofOne- and Two-Electron Atoms (Springer-Verlag, Berlin,1957).
2) B. Edlen: in Handbuch der Physik, edited by S. Fliigge(Springer-Verlag, Berlin, 1964) Vol. XXVII, p. 80.
3) K. Ishii et al.: RIKEN Accel. Prog. Rep. 30, 78 (1997).
4) K. Ishii et al. : Phys. Scr. T 73, 73 (1997).
5) R. D. Cowan: in The Theory of Atomic Strcture andSpectra (University of California Press, Berkley, 1981).

91

RIKEN Accel. Prog. Rep. 31 (199B)

Beam Foil Spectra of Highly Charged Krypton Ions
in Visible Region
K. Ishii, T. Nakano, S. Kawae, K. Ando, H. Oyama, and T. Kambara
Beam-foil spectra of highly charged Kr ion at theenergy of 1.0 and 2.5 MeV /amu were recorded in theregion between 200 and 700 nm. Photons emitted fromthe Kr ion after its passage through a thin carbon foil
were dispersed by a Czerny-Turner spectrometer anddetected by a liquid-nitrogen cooled CCD detector.
The detector placed at the exit focal plane covered thewavelength range of about 80 nm. In order to reduce
the Doppler width, the spectrometer was refocused. 1)
The line width of 0.3-0.4 nm was thus achieved. Comparison of the relative intensity change in the spectra
recorded at two different beam energies has provided
the charge state identification of the observed lines. A
portion of the spectra in the range 227- 316 nm at thebeam energy of 1.0 MeV /amu is shown in Fig. 1.

...

<"l

80

~

~

~ 60

X

.e
til

N

~ 40

j

~c:

"

c:

..r

~

~
~

20

230

240

250

u
~

~
l"-

~

260

N

~

cD

"

c:

~

"c:

~

10

:!:
~

;i;

<"l
N

§:
~

~
X

-§

...

~

N

~

C

280

WavelengthCalc.
2387.882456.34
2534.142563.902618.632695.732736.912777.962793.922856.722862.132993.273068.403078.103095.79
3141.23
Std. dev.=

diff.
0.07
0.03
-0.20
0.10
-0.04
-0.17
-0.03
0.12
0.02
0.03
0.00
0.08
-0.08
0.02
-0.04
0.00
0.09

Classification
XVII (Ca) n=11- 12
XIX (Ar) n=12-13
XXI (8 ) n=13-14
XIX (Ar) n=15-17
XXIII(8i) n=14-17
XVI (8c) n=11-12
XVIII(K) n=12-13
XX (CI) n=16-18
XX (Cl) n=13-14
XVIII(K) n=15- 17
XXII(P) n=14-15
XXI (8 ) n=17- 19
XVII (Ca) n=12-13
XIX (Ar) n=16- 18
XIX (Ar) n=13- 14
XXI (8 ) n=14- 15

~

XIO

~
~
~~

x~

<"l
N

Ol

r.

to!.

1!

c:

C:cD
"~
mit

Ui'

~

8c:

~<x

290

300

310

Wavelength (nm)Fig. 1. A portion of Kr ion spectra of 1.5 MeV / amu
energy at immediate down stream of the foil.

Using the hydrogenic term energies, the wavelengths
and the transition probabilities for the Rydberg transitions were calculated. 2 ,3 ) All the lines are thus classified as transitions of high n, R levels in Kr XIX to----..Kr XXVI, among which the relatively strong lines arelisted in Table 1. Weak lines not included in the table
are Don > 3 transitions. In the fourth column, the

92

Obs.
2387.95
2456.372533.94
2564.00
2618.592695 .56
2736.882778.082793.942856.75
2862.132993.35
3068.323078.123095.75
3141.23$x

270

Table 1. Observed and calculated transitions of Kr ions.

element symbol of the isoelectronic sequence to which
the line belongs is shown in parenthesis. Almost all
the lines except those which are very weak/broad wereidentified over the spectra from 195 to 700 nrn in thisway.
The further study on n-dependence of the level population in a charge state is now in progress. This may
be practiced by calibrating the sensitivity of the spectrometer system against the standard light source.
References
1) J. O. Stoner, Jr. and J . A. Leavitt: Appl. Phys . Lett.
18, 477 (1971).
2) H. A. Bethe and E . E. Salpeter: in Quantum Theory ofOne- and Two-Electron Atoms (Springer-Verlag, Berlin,1957).
3) B. Edlen: in Handbuch der Physik, edited by S. Flugge(Springer-Verlag, Berlin, 1964) Vol. XXVII, p. 80.

RIKEN Accel. Prog. Rep. 31 (1998)

Lifetimes of Intercombination Lines in Highly Charged Nb
R. Hutton, Y. Zou, S. Huldt, 1. Martinson, K. Ando, B. Nystrom,
H. Oyama, and T. Kambara
In an earlier report l ) we discussed beam-foil spectroscopy (BFS) of highly charged Nb ions. The work
reported in Ref. 1 was done using the BFS set up described by Ando et al. 2) Recently, we have upgraded
the BFS spectrometer with a CCD detection system.
This upgrade was described in the last year progress
report. 3 ) We have now repeated some of the Nb work
using the CCD detector. In Fig. 1, we compare delayed

100
90

b

80
~

'2

70

~60

-e

":. 50

C

'§ 40
G)

,~Lo
20
10

spectra, i.e. spectra taken with a 10 mm separation
between the exciter foil and the spectrometer entrance
slit, for 183 MeV Nb taken with the CCD (Fig. 1a)and with the old detection system (Fig. 1b). Figure lashows clearly the improved signal/noise ratio obtainedwith the CCD system. By measuring intensity as afunction of foil position we could measure the decay
time of all lines focused on the CCD chip. As theresults of Refs. 4 and 5, that the measured lifetime of
the Mg-like 3s 2 I80 - 3s3p 3 PI line is shorter thantheory by a significant amount (around 30 percent)
was confirmed. The same was found for the AI-like3s 23p 2 P3 / 2 - 3s3p2 4 P5 / 2 line. A number of otherintercombination lines appear in the spectrum shownin Fig. la (e.g. the Si-like 3s 2 3p2 3 P I ,2 - 3s3p 3 582
lines) and these decay times are under investigation.
Using the CCD the decay of the line profile can bemeasured. By generating decay curves for different
parts of the line profile we found a non-unique lifetime.
This interesting finding is discussed more in Ref. 6.
References

190

195

200

205

210

215

220

225

230

wavelength, A

Fig. 1. Beam foil spectra of 183 MeV Nb taken using
two different detector systems. Figure La shows the
spectrum recorded with a CCD detector system. Figure
1. b shows the same spectrum recorded using a single
channel (ceratron) detector. The peaks are temporarily
identified as (1): AI-like 3s 23p 2 P I / 2 - 3s3p2 4 P I / 2 , (2):Si-like 3s 23p2 3 PI - 3s3p 3 S S2, (3): Mg-like 3s 2 I So 3s3p 3 PI and (4): AI-like 3s 2 3p 2 P 3 / 2 - 3s3p2 4 P S / 2transitions.

1) R. Hutton et al.: RIKEN Accel. Prog. Rep. 28, 69(1995).
2) K. Ando et al.: J. Spectr. Soc. Jpn. 41, 370 (1992).
3) R. Hutton et al.: RIKEN Accel. Prog. Rep. 30, 146(1997) .
4) R. Hutton et al.: RIKEN Accel. Prog. Rep. 30, 79(1997) .
5) R. Hutton: Proc. 8th Int. Conf. on the Physics of Highly
Charged Ions, Omiya, 1996, Invited contribution, Phys.
Scr. T 73, 25 (1997).
6) R. Hutton et al.: RIKEN Accel. Prog. Rep. 31, 94(1998).

93

RIKEN Accel. Prog. Rep. 31 (1998)

Inherent Problems with Beam-Foil Lifetime Measurements
R. Hutton, Y. Zou, S. Huldt, 1. Martinson, K. Ando, B. Nystrom,
T. Kambara, and Y. Awaya
We have attempted to measure the lifetimes of thels22p 2 P1 / 2,3/2 levels of Li-like argon using the techniques of beam-foil spectroscopy (BFS). This measurement was done to help understand a series of measurements for the lifetime of the 3s 2 180 - 3s3p 3 PI
intercombination line in Mg-like ions. I) There can be
no shortcomings in the theoretical treatment of Li-likeions whereas such is not so obvious in the case of Mglike ions. In the experiment here the signal (total spectralline plus background) was recorded using a CCD
detector system installed on a 2.2 meter grazing incidence spectrometer. 2) Figure 1 shows a full CCD image taken using a 1200 lines/mm grating installed on
the spectrometer. The 28 1/ 2 _2 P3 / 2 line is seen to beisolated in the spectrum taken at a time delay of 50

260

Li-like Argon resonance line

352.59352.8

353.01353 .2 2 353.43

A(A)280~----~----~----~----~----~----~

Fig. 2. The intensity of the line shown in Fig. 1 as afunction of the time of flight (t) corresponding to theexciter foil position. It is clear that the decay of thisline cannot be described by a single exponential decay.

260.to:'" 240
::l

.e
«l

6
.;;;
c:
Q)

220

112oo
180

~

340

_____________rJ
345

350

L
'

~,~

355

__~__~~
360

365

370

Wavelength , A

Fig. 1. Spectral recording in the region of the Li-like
Argon 28 2 SI/2 - 2p 2 P 3 / 2 line. The line is seen to beasymmetric, but clear of any spectral blends.

ps. Figure 2 shows this line in more detail, recorded ata number of foil positions. This shows that the line isasymmetric and that the shape changes as a functionof foil position which ·corresponds to the time of flightafter the excitation. Thus, no unique value for the decay time of this line can be found, instead a range ofvalues were obtained depending of how the data was94

analysed. In a recent experiment a similar behavior
was seen for the decay of the Mg-like Nb intercombination line. 3 ) These phenomena may be caused bysatellite lines contaminating the decay of the line ofinterest. These problems need to be understood, especially as to why in some cases measurements give agood agreement with theory, as BFS is still the mostgeneral method for measuring lifetimes of atomic energy levels of highly charged ions.
References
1) R. Hutton: Proc. 8th Int. Conf. on the Physics of Highly
Charged Ions, Omiya, 1996, Invited contribution, Physica Scripta T 73, 25 (1997).
2) R. Hutton et al.: RIKEN Acce!. Prog. Rep. 30, 146(1997).
3) R. Hutton et al.: RIKEN Acce!. Prog. Rep. 31, 93(1998).

RIKEN Accel. Prog. Rep. 31 (1998)

Electron Spectra Arising from Collisions between
50 ke V N5+ and Ar
D. Chiba, T. Kamei, T. Takayanagi, K. Wakiya, Y. Kanai, and Y. Nakai
Multiple-electron capture in slow ion-atom collisions
produces multiply excited ionic states, which may reveal their quantum properties through analyses of thesubsequent photon or Auger electron emissions. The
angular distribution of Auger electron emission, measured with respect to the projectile beam direction,
carries a complete information on the ML (magnetic
substate) alignment determined in the capture process.
For measurement of the angular distribution of
A uger electron emission arising from the collisions between highly charged ions and neutral atoms, we haveconstructed a toroidal-type electron energy analyzer. 1)
Since March 1996, we have installed the above analyzer at the beam line of the RIKEN 14.5 GHz ECR ion
source (Caprice), and have tried to measure the Auger
electrons from N3+** (18 23l3[') produced by the collisions of 50 ke V N 5 + on Ar as a test of our apparatus.2 )The angular distributions of Auger electrons emitting from N 3+** (18 23l3l') were measured with a channel electron multiplier (CEM). Typical spectrum measured at O-degree with respect to the projectile beamaxis is shown in Fig. L The upper states of Auger
decay are indicated in Fig. 1. Our O-degree spectrum
agrees with that by Kitazawa et al. 3) in both the energy and relative intensity. As for the other angles, wehave obtained spectra but with a larger backgroundcompared with that of O-degree because of the kinematics effects. We will make an effort to suppress the-' 0 '

' P"

I

I

' I"

'p,1 '0" I 'P'' I'''I

N S , -Ar(O-deg)

I ' po I

I

'P"

I
' F'
(J)

c
(l)

c

15

20

25

30

35

Electron Energy (eV)Fig. 1. The O-degree Auger spectrum from N 3 +** (Ii 3l31')
states produced by double-electron capture in the collisions of 50 keY-beam N 5 + ions against Ar atoms.

background.
References
1) H. A. Engelhardt, W. Back, and D. Menzel: Rev. Sci.
lnstrum. 52, 835 (1981).
2) Y. Tamagawa et al.: RlKEN Accel. Prog. Rep. 30, 145(1997).
3) S. Kitazawa et al.: Physica Scripta T 73, 207 (1997) .

95

RIKEN Accel. Prog. Rep. 31 (1998)

VUV Photon Emission Spectroscopy ofSlow, Highly Charged Ions
B. Nystrom, Y. Nakai, T. Kambara, and Y. Kanai
To enable studies of the low energy, highly-charged
ion-atom collision processes using Photon Emission
Spectroscopy (PES), we installed a 1 m grazing incidence spectrometer, Minutemann 310 G, at the 14.5
GHz Caprice l ) ion source. The purposes are (1) tostudy the collision processes when highly charged ionscollide with neutral atoms, and (2) to study the electronic structure of highly charged ions, using the ionatom collision as a way to create excited ions. Ions
from the ion-source is momentum-analyzed and focused on an effusive gas-target. The target-region isobserved with the spectrometer at an angle of 54.7 degrees forward with respect to the beam-direction. Thisobservation-angle is selected because at this angle, thelight of different polarizations contribute equal to theamount of emitted photons. At this observation-angle,
the light emitted from the projectiles will have a small
Doppler-shift, information that might be useful in thesymmetric collision-systems where both projectile-ion
and target-atom might end up in equal excited states,e.g., He 2 + + He. 2 ) The spectrometer is working in thegrazing incidence: the angle of incidence is 86 degrees.
The entrance slit can be selected to be 100, 50 or 20
J-Lm. The instrument can be used with four different
gratings with 133.3, 600, 1200 or 2400 mm- 1 ruling.
The wavelength-range that can be covered and the resolution that can be obtained are then defined by the
combination of slit and grating that is used with thespectrometer. Figure 1 shows a spectra recorded whena beam of N 5 + collides with air as the target-gas. This
spectra was measured with 100 J-Lm slits and the 133
mm- l grating giving a wavelength range 100-3000 A
at a theoretical resolution of FWHM = 7.5 A. This
spectra is the first successful test-measurement per-96

N~+ + Air

3000

2500

I

2000

f
~

If
1500

f

I

.E

~

1000

500

o~~~~--~~--~--~~--~--~~
o
100
200
300
400
500
600
700
800
900
1000

Wavelength [AI

Fig. 1. Spectra recorded when 70 keY N 5 + collides withair. The position of the 1S22S 2S 1 /2 - 1s 23p 2P 1 / 2,3/2
transitions in N V (the spectra of N 4 +) are marked in
the figure. Note that this is two unresolved transitions,that are marked in 1st, 2nd, 3rd and 4th order respectively.

formed, where the resolution is close to the theoreticaland the spectra is calibrated with known transitions. 3 )Note that most of the transitions in this spectra canbe identified, but since this measurement is made atrather low resolution it is not possible make any further
conclusions.
References
1) Y. Kanai et al.: RIKEN Accel. Prog. Rep. 30, 168(1997).
2) B. Nystrom et al.: Physica Scripta T 73, 212 (1997).
3) R. L. Kelly: J. Phys. Chem. Ref. Data 16 Supl. 1 (1987).

RIKEN Accel. Prog. Rep. 31 (1998)

Defect Production and Electronic Excitation in
Ion-Irradiated High-T c Superconductors t
N. Ishikawa, Y. Chimi, A. Iwase, K. Tsuru,*1 O. Michikami,*2 and T. Kambara
We have measured the irradiation fiuence dependence of c-axis lattice parameter for the EuBa2CU30yhigh-Tc superconductor irradiated with various ionsfrom CI to Au over the wide energy range from 80
MeV to 3.80 GeV. The irradiating ions were as follows: 120 MeV 35Cl, 90 MeV and 200 MeV 58Ni,
125 MeV 79Br, 80 MeV and 200 MeV 127I, and 120
MeV 197 Au available from the tandem accelerator at
JAERI-Tokai; and 3.54 GeV 136Xe and 3.80 GeV
18 1Ta available from RIKEN Ring Cyclotron. In thisrange of energy and ions, defects were uniformly introduced along the sample thickness, and we could
exclude the effect from ion implantation. We havemeasured the X-ray (Cu Ka) diffraction pattern both
before and after the irradiation in order to estimate
the change in c-axis lattice parameters. We have observed a linear increase of the c-axis lattice parameterwith the fiuence,l) <1>, as can be seen in Fig. 1. For alow energy (~2 MeV) ion irradiation, the (D.c/co)/<I>
which corresponds to the defect production rate is
proportional to the nuclear stopping power Sn: 1) i.e. ,(b..c/co)/<I> = aS n , where a = 3 x 10- 16 mg/MeV. The
contribution of electronic excitation to the (D.c / co) / <I>value is precisely estimated by assuming that the observed (~c/co)/<I> value is the sum of the contributions of elastic displacement and of electronic excitation. The former contribution is expressed as a linear
function of Sn as stated above. The latter contribution
is designated as [(D.c/co)/<I>]electronic and was plotted asa function of dJ / dx in Fig. 2, where dJ / dx is the number of atoms ionized per unit path length. The value ofdJ / dx was calculated based on the Bethe formula. 2- 4)
The figure shows that [(b..c/co)/<I>]electronic is scaled by(dJ/dx)4. Since dJ/dx is the number of atoms ionized per unit path length of projectile and is not theenergy deposited to the target, this suggests that theline density of induced space charge is responsible forthe defect production in high-Tc superconductors. 4).:.

10- 14/-(dJ/dx)4

,I'

:.

.,:

/i.:"
1 .5

120MeV Au

•

,:::.

200MeV I•

10- 18oL....,4, ---'--'--...L--'--"-'-......1-'--c05~--'---'---'---'-'-'-~1061
dJ/dx ( arbitrary units),,/ /80 MeV I

o

-g
<1

/

, ,//,'''''3:a:ev Ta

Fig. 2. [(~c/Co)/1>] electronic as a function of dJ/dx. The
dotted line shows the line proportional to (dJ / dx) 4 .

0.5
0 --: ,,' "~5l ",-•~ ~,--~ ,--, ---'

3.54GeVXe__ x __
15Fig.
1.
The ~c/co value as a function of 1> for
EuBa2 CU3 Oy irradiated with high energy ions, where~c/co is the increment in c-axis lattice parameter normalized by the c-axis lattice parameter before irradiation, and 1> is the fluence of irradiation.

References
1) N. Ishikawa, A. Iwase, Y. Chimi, H. Maeta, K. Tsuru,
and O. Michikami: Physica C 259, 54 (1996).
2) R. L. Fleischer, P. B. Price, R. M. Walker, and E. L.
Hubbard: Phys. Rev. 156, 353 (1967).
3) H. A. Bethe: Ann. Physik 5, 325 (1930).
4) N. Ishikawa, Y. Chimi, A. Iwase, H. Maeta, K. Tsuru,
O. Michikami, T. Kambara, T. Mitamura, Y. Awaya,
M. Terasawa: Nucl. Instrum. Methods Phys. Res. B.
"( to be published).

Condensed from the article in Nucl. Instrum. Methods Phys.
Res. B. (to be published)*1 NTT Integrated Information & Energy Systems Laboratories, Information Hardware Systems Laboratory*2 Faculty of Engineering, Iwate University

97

RIKEN Accel. Prog. Rep. 31 (1998)

Effect of Heavy-Ion Irradiation on the Bi-Based Superconductors
N. Kuroda, N. Ishikawa, S. o kayasu , A. Iwase, H. Ikeda,* R. Yoshizaki,*and T. Kambara
Columnar defects produced by the irradiation withhigh-energy (f'V 1 Ge V) heavy ions can pin magnetic
vortices much more effectively than the other kindsof defects such as point defects.
The Bi-basedoxide superconductors can be classified into three
types depending on the number of CU02 stackings:
Bi 2Sr Z Ca n- l CunO y , in which n = 1, 2, 3. We haveinvestigated the pinning properties of the three typesof Bi-based superconductors with columnar defects.
Bi2+xSr2_(x+y)LayCu06+§ (Bi-2201) (Tc ~ 20 K)
and Bi2Sr2CaCu20y (Bi-2212) (Tc ~ 90 K) single
crystals were grown by the traveling-solvent floating zone (TSFZ) method.
Highly c-axis-oriented
Bi1.8Pbo.4Sr1.8Bao.2Ca2.2Cu3.o0y (Bi-2223) ceramics
with T c ~ 108 K were synthesized by means of a hotpress technique. 1) These materials were irradiated by
the 3.5 GeV 136Xe31+ beam at RIKEN Ring Cyclotron
Facility to produce columnar defects along c-axis. In
all cases, the pin density (npin) was 1.2 x 1011 /cm 2,
which corresponds to a doseequivalent matching field
Bq, = npin CPo = 2.4 T, where CPo is the flux quantum. The irradiation reduced Tc by 5, 3, and 1 K for
Bi-2201, Bi-2212 and Bi-2223, respectively.
We have investigated the irreversibility line whichmarks the onset of reversible flux motion in the magnetic field (Bex) versus temperature (T) phase diagram, using the AC loss peaks (T p) in the temperature dependence of the imaginary part of susceptibility (X"). When the amplitude of AC field is low, 0.5Oe, the AC response was linear. For the linear response the irreversibility line determined by the ACloss peaks corresponds to the constant resistivity linewith Pab = 0.2257rwdJ.Lof in Bex-T plane,2) where w is
the width of the sample, d the thickness, and f the frequency of the AC field . Figure 1 shows the irreversibility lines determined by the criterion of Pab ~ O.lJ.LOcm(at frequency of 5 kHz and AC field of 0.5 Oe) for
Bi-2201, Bi-2212 and Bi-2223 before and after the Xe

Cryogenics Center, University of Tsukuba

98

6

before irradiation0
Bi-2201
0Bi-2212Bi-2223
after irradiation• Bi-2201
Bi-2212... . Bi - 2223

5

L;

.

4

S 3
cc

;

2

O~~~~~~~~~~~"-~
O. 2 O. 3 O. 4 O. 5 O. 6 O. 7 O. 8 O. 9 1. 0

T;r/TcFig. l. Irreversibility lines for Bi-2201, Bi-2212 andBi-2223 before and after the Xe irradiation.

irradiation. After the irradiation all the irreversibilitylines show strong shifts to the higher reduced temperature. Xe irradiation has improved the pinning properties strongly for Bi-2201, Bi-2212 and Bi-2223. Another interesting feature was observed for the Bi-2201
and Bi-2212 single crystals after irradiation. That is,a kink appeared in the irreversibility line at about
0.5Bq,(~ 1 T), above which the motion of the vortices lying in the interstitial spaces between columns isbelieved to be relevant to the irreversibility line,3) asshown by the arrows in Fig. 1.
References
1) H. Ikeda et al.: Jpn. J. Appl. Phys. 29, L430 (1990) .
2) E. H. Brants: Phys. Rev. Lett. 71, 2821 (1993).
3) L. Krusin-Elbaum et al.: Phys. Rev. Lett. 72, 1914
(1994).

RIKEN Accel. Prog. Rep. 31 (1998)

Irradiation Effects of Swift Heavy-Ion on
Polycrystalline La1.85SrO.15Cu04
T. Mitamura, M. Terasawa, X.-J. Fan, T. Kohara, K. Ueda, and T. Kambara
For practical application of the high-temperature superconductor, the achievement of high critical current
density under high magnetic fields is very important,because the critical current density tends to decrease
rapidly by easy motion of vortices when the temperature approaches the critical temperature. Enhancement of the pinning strength in high-T c cuprates due
to introduction of parallel or multi-direction columnar defects by ion irradiation has been reported.1- S) In
the present study, a high-temperature superconducting material, polycrystalline La1.8SSro.1SCU04, (henceforth LSCO), was irradiated by swift heavy ions in order to introduce columnar defects as vortex pinning
centers, and the characteristics of superconductivity
were investigated.
The polycrystalline LSCO bulk specimens with thesurface of about 2 mm x 10 mm and thickness of
0.1 mm were irradiated at room temperature in a highvacuum by the 3.5 GeV 136Xe31 + ions which were accelerated by RIKEN Ring Cyclotron. Ion irradiation
was carried out by two ways; single direction irradiation perpendicularly to the surface of specimen (parallel irradiation), and multi-direction irradiation (splay
irradiation). In the present case, the splay irradiation was performed by combining two irradiation directions: the direction normal to the specimen surface andthe direction tilted at an angle of 0 from the normalline (0 degree splay-irradiated specimen). In the splay
irradiation, total irradiation doses were set to be thesame amount for each direction. The measurementsof magnetization hysteresis and vortex creep were carried out by a Quantum Design SQUID magnetometerby applying an external magnetic field normal to thesurface of specimen.
Figure 1 shows examples of the magnetization hysteresis loops obtained at temperature 5 K for a 0 = 0(parallel) as well as irradiated specimen, and 0 = 5
and 0 = 45 degree splay-irradiatedspecimens with thesame total irradiation dose of B¢ = 6.0 T. (B¢ is thefield-equivalent irradiation dose, and the vortex density at B¢ = 1.0 T corresponds to the irradiation doseof 0.5 x 10 11 Xe/cm 2 ) From the figure, it is suggested
that total strength of vortex flux pinning depends on
the spray-irradiation angle O. It was observed that thecolumnar defects introduced by low angle (below about
10 degree) splay-irradiation can more strongly pin thevortices. In the other experiments, the irreversibility
line, which corresponds to the boundary dividing thepinning region of magnetic flux lines (vortices) fromthe complete depinning region in the temperature-vs.magnetization plane, is most effectively enhanced also
at 0 = 10 degree splay-irradiation. Optimum splayirradiation angle for the most effective vortex pinningis tentatively obtained to be about 10 degree.
The examples of normalized changes of magnetic relaxation (vortex flux creep) are illustrated in Fig. 2
for three different irradiation modes. In the figure, the splay-irradiation angle was 10 degree. The
magnetic relaxation proceeds slowest in the splayirradiated specimen, which is considered an evidence
that the configuration of columnar defects producedby the splay-irradiation is more effective for vortex
pinning than that by the parallel irradiation. Many
theoretical explanations have been proposed so far. 6)
We are now making the comparison of our data withthose theoretical predictions.

0.95

~=

~

SplayedParallel
0.9

103

time(sec)

Fig. 2. Comparison of the normalized magnetic relaxation curve of the unirradiated specimen with those of
the parallel and B = 10 degree splay-irradiated polycrystalline LSCO specimens.

References
o

5000

10000

H (Oe)

Fig. 1. Comparison of magnetic hysteresis loops of the 3.5
GeV 136Xe31+ ion between splay-irradiated (B = 5 and45 degree) and parallel-irradiated polycrystalline LSCO
specimens. The total irradiation dose corresponds toB</> = 6.0 T.

1) V. Hardy et al.: Nucl. Instrum. Methods Phys. Res. B
54 , 472 (1991).
2) Th. Becker et al.: Physica C 245, 273 (1995).
3) M. Terasawa et al.: Physica C 235, 2805 (1994).
4) T. Hwa et al.: Phys. Rev. Lett. 71, 3545 (1993).
5) Th. Schuster et al.: Phys. Rev. B 51, 16358 (1995).
6) Y. Yeshurun et al.: Rev. Mod. Phys. 68, 991 (1996).

99RIKEN Accel. Prog. Rep. 31 (1998)

Observation of Columnar Defects in Layered Materials Bombarded
by 136Xe+31, 181Ta+ 37 , and 209Bi+ 37 by STM and TEM
N. Nishida, H. Sakata, S. Kaneko, Y. Ono, Y. Taguchi, and T. Kambara
In some materials the high-energy heavy ions generate columnar defects which are linear damage tracks of
rvl0 nm diameter along the tracks of heavy ions. Recently, the columnar defects in copper-oxide high temperature superconductors have attracted attentions,because they are effective to pin vortices in high magnetic fields. The formation mechanism of colurn anar defects has not been well understood: Heavyions may locally melt the crystal and generate amorphous columns along their tracks, or the recovery
time of electrons to ionized atoms are so long thationized atoms change their position before they become neutral and thus the crystal is destroyed locally.
We have reported 1) that the 3.4 GeV 136Xe+ 31 ionsgenerate columnar defects in mica or high-T c oxidesuperconductors with diameter of about 10 nm, but
not in 2H-NbSe2 and 1T-TaS2 at all. In this report
we mention the experimental results of the 18 1Ta+ 37
and 209Bi+ 37 bombardments on the 2H-NbSe2 and 1TTaS2 single crystals at room temperature at the E5abeam line of RIKEN Ring Cyclotron Facility. The
columnar defects were observed to have been generated by 181Ta+37 and 209Bi+ 37 both in 2H-NbSe2 and
1T-TaS2. In Fig. 1 shown is a scanning tunnelingmicroscope (STM) image of a columnar defect generated by 181Ta+37 in 2H-NbSe2; a triangular-shaped

contrast can be seen around a columnar defect. This
has also been observed by transmission electron microscope (TEM). It is not known what is the meaning of
the triangular region; a structural change or a changeof electronic states around a columnar defect. In Fig. 2
shown is a TEM photograph of tracks of 181Ta+37 in
1T -TaS2. Ta ion beam was injected into IT -TaS2 crystal slightly canted against the c-axis and TEM photograph was taken with the electron beam parallel tothe c-axis. Discontinuous tracks can be seen. Thismeans that an amorphous columnar region is generated discontinuously along the track. This amorpous
structure has been confirmed by the TEM and STM
observations. Thus, in 2H-NbSe2 and IT-TaS2, columnar defects have been generated by using heavy ions ofTa and Bi, but columnar defects are found not to becontinuous in IT -TaS2 or the border region is vague
in 2H-NbSe2; these features are different from thosein Bi2Sr2CaCu20x. These observations will be relatedwith a formation mechanism of the columnar defects
induced by high energy heavy ions and will help tounderstand the physics. Consideration is under way.

Fig. 2. TEM photograph ofthe 181Ta+37 beam bombarded
1T -TaS2. Amorphous columnar region is seen to begenerated discontinuously.
Fig. 1. Columnar defects observed by STM in 2H-NbSe2.
The black region is a columnar defect of amorphous
structure. A triangular shape region around the columnar defect has a crystal structure.

100

References
1) N. Nishida et al. : RIKEN Accel. Prog. Rep. 29, 123(1996).

RIKEN Accel. Prog. Rep. 31 (1998)

Experimental Study of Single Event Burnout (SEB)
Hardening on POWER MOSFET
S. Matsuda, S. Kuboyama, S. Shugyo, T. Suzuki, K. Sugimoto,T. Hirose, H. Ohira, T. Kohno, and M. Kase
Semiconductor devices, which are essential in artificial satellites and spacecrafts, are degraded by radiation in space. The radiation environment around theearth includes the electrons and protons trapped by
the Earth's magnetosphere, and the solar protons andheavy ions in galactic cosmic rays. It is well known
that the impingement of high energy heavy ions on
semiconductor devices causes single event phenomenon(SEP) like single event upset (SEU) on memory device, single event latch up (SEL) on CMOS, LSI etc.,
and single event burnout (SEB) caused by the heavy
ion passing through the active area of POWER MOSFET. NASDA (National Space Development Agencyof Japan) has studied SEB and single event gate rapture (SEGR) on POWER MOSFET with heavy ionsavailable from the RIKEN Ring Cyclotron. 1)
We are developing 250V POWER MOSFET to be
used for the future artificial satellites which will belaunched in 2002. To fix the design parameters of
the POWER MOSFET, we have performed irradiation
test on several types of samples with a beam of Ni 25 +at 7.6 MeV lu (440.8 MeV) and studied the breakdown

voltage data concerning with SEB and SEGR. Afteran energy degrader the energy of beam on the samples
was about 260 MeV lu where the linear energy transfer(LET) of the ions in the material (Si) was about 27
MeV l(mg/cm2 ) and the range was about 36 p,m (Si).
It is obvious from the former experimental data thatthe single event effect (SEE) tolerance of POWER
MOSFET depends on the BVDs (Drain-Source Breakdown Voltage) of POWER MOSFET. 2) When the
BVDS is higher, the tolerance is higher; but the highBV DS leads to a high Ron value (Ron : a resistancevalue when the transistor goes "ON" state). To keepa low Ron value on the same BV DS, it is necessary toenlarge the chip size, then the capacitance increases
and the switching speed slows down. Therefore, we
prepared several types of samples that were fabricatedwith various parameters for space applications. The
design parameters on each samples together with theirradiation test results are shown in Table 1. Other
irradiation test data (underlined data) mainly performed on SEGR at Brookhaven National Laboratory
in USA are shown, too.

Table 1. The design parameters on each samples and irradiation test data.
process condition
chip design
result of SEGR test
result of SEB test
description BVds n+ layer(As) dose Igate thickness cell geometry Ip-pitch SEB threshold(Vds) SEGR threshold(Vgs) remark
Tc=100°C
6F
4.00E+15
BooA
stripe250V
250V<
9tl m 190.200.200 210
4.00E+15
Tc=Ta
250V
BooA
square140V
6C
3tl m 130. 135
4.00E+15
250V
stripe175V«SEB threshold) Tc=100°C
BooA
6H
3tl m 165. 173. 175. lB5
Tc=100°C
4.00E+15
300V
BooA
square2C
190V
3tl m 160. 170
Tc=100oC
250V
4.00E+15
square
BooA
61
200V<
5tl m 125. 127
Tc=100°C
stripe7F
250V
4.00E+15
1000A
200V<
9tl m 190.190 195.200
stripeTc=100°C
BOO A
9j.t m 240 240
10F
300V
3.50E+15
250V<
remark : temperature condition on SEGR test
Tc : case temp.. T a : ambient temp.
The underlined data was aquired at Brookhaven National Laboratory.

First , we compared the effect of cell geometry. From
the former study, the uniformity of electronic fields inthe chip contributes to improve the SEB tolerance. Table 1 shows that the stripe pattern cell has better SEB
tolerance than the square one has. The reason is thatthe square pattern cell leads to 2 and 3 dimensional
localized charge at the corner of cell. (On the other
hand, however it is also said that the cell geometry
does not influence the failure threshold of SEGR. 3))
As a result , the cell geometry was determined to be
stripe pattern.
Second, we compared the effect of p-pitch size. In
ordinary, if p-pitch is smaller, the SEB tolerance increases; but the Ron characteristic worsens, at the sametime. Therefore, p-pitch size had to reduce under 10
p,m on our samples. From the data of former irradi-

ation test, the SEB threshold was 120 V on 16 p,m ppitch samples. In this test, we irradiated 9 p,m p-pitchsamples, and as the Table 1 shows the result was better
than 16 J.Lm p-pitch, and better than 3 p,m p-pitch, too.
We expect there is an optimum p-pitch size of POWER
MOSFET, and continue to analyze the data.
References
1) S. Kuboyama et al.: IEEE Trans. Nucl. Sci. NS-39,
1698 (1992).
2) K. F. Galloway et al.: Proc. 2nd Int . Workshop on Radiation Effects of Semiconductor Devices for Space Application, p. 88 (1996).
3) J. L. Titus et al.: IEEE Trans. Nucl. Sci. NS-42, 1928
(1995).

101

RIKEN Accel. Prog. Rep . 31 (1998)

Change of Site Occupancy of Hydrogen in Nb
on Alloying with Undersized Mot
E. Yagi and S. Koike*
Regarding the effect of alloying on the terminal solubility of hydrogen (TSH) in group Va metals (V, Nb
and Ta), it has been reported that for undersized metal
solutes, e.g., Nb in Ta and Mo in Nb, the TSH increases
rapidly with solute concentration. l ,2) To understandthis effect the lattice location of hydrogen in Nb-Mo
alloys has been investigated by the channeling method
utilizing a nuclear reaction 1 H(l1 B,a)aa with an 11 B
beam of an energy of approximately 2 MeV. 3) In thismethod the hydrogen can be detected by measuring
the emitted a-particles. Previous studies on H in Nb3at%Mo and Nb-10at%Mo alloys demonstrated that a
portion of H atoms are trapped at room temperature
by Mo atoms to be located at the sites displaced fromthe tetrahedral (T) sites by about 0.6 A towards the
Mo atoms substituting Nb atoms (trapped sites) andthe remaining H atoms are located at T sites. They
also demonstrated that the number of H atoms locatedat the trapped sites per one Mo atom (the trapping efficiency ,,) decreases from 0.7-1.0 in the Nb-3at%Mo
alloy to 0.2-0.3 in the Nb-10at%Mo alloy. 4-6) In thepresent study the lattice location of hydrogen in a moreconcentrated Nb-20at%Mo alloy is investigated as in aprevious study.3)
The lattice parameter of this alloy was measured to
be about 0.8% smaller than that of Nb. Hydrogen
was doped from the gas phase up to the three different
concentrations (CH ) 2.6,4.2 and 8.0 at%.
The results are shown in Fig. 1. For C H = 2.6 and
4.2 at% the angular profiles of the a-particle yields (aangular profiles) are very similar. Being superposedon a shallow dip, they exhibit subpeaks at the angular
positions expected for the T-site occupancy which areindicated by arrows. 7 ) The subpeaks characteristic of
the trapped-site occupancy4) are not observed. These
results suggest that a large portion of H atoms are located at T sites, and some portion of them are locatedat the sites which give the shallow dip in the (100) and(110) a-angular profiles. Namely, those sites are shadowed by (100) and (110) atomic rows. These shadowedsites are considered to be octahedral (0) sites. For
CH = 8.0 at%, similar subpeaks are still observable,
but the shallow dips for the (100) and (110) channels
become much shallower or they disappear.
The lattice locations of hydrogen and its distribution
were determined by fitting the calculated a-angularprofiles to the observed ones. It is concluded as follows:
In Nb-20at%Mo alloys, H atoms are located at both T
and 0 sites, but not at the trapped sites, i.e., " =O. For C H = 2.6 and 4.2 at%, the fraction of the 0site occupancy is 20- 30%, while, for C H = 8.0 at%, it
remarkably decreases to 0-10%.
Condensed from the article in J. Phys. Soc. Jpn. 67, 340(1998)
Dept. Phys. II, Fac. Sci., Science Univ. of Tokyo

102

(oj

O~

"~

u.

«~

III

I
• H

:-v-V-1[1.5

~

(Q)

,1""

'00( ...

J

A"-{'iv-- - rr
V
0.5

4

1

0

1

4

4 2 0 2ANGlECd.gl

4

-,

0

I

Fig. 1 Channeling angular profiles of a-particle yield (.)
and the yield of 11 B ions backscattered by host metal
atoms (0), obtained at room temperature for Nb-20
at%Mo alloys containing H by (a) 2.6, (b) 4.2, and (c)8.0 at%. The full and dashed curves have been drawn
to guide the eye. In the insets the projections of T
and 0 sites onto the plane perpendicular to the channel in question are shown by open squares with relative
weights. The open circles and lines represent the projections of atomic rows and planes, respectively.

The appearance of the O-site occupancy in Nb20at%Mo alloys can be understood as a result of the reduction of the energy difference between T and 0 sites
due to the decrease of the lattice parameter on alloying with undersized Mo atoms. The trapping model l )proposed as a mechanism for the enhancement of theTSH in Nb on alloying with Mo atoms is considered
to be effective in the region of the Mo concentration
lower than about 5 at%. The reduced fraction of the
O-site occupancy at CH = 8 at% is considered to be
due to the interaction between H atoms.
More detailed description is given in Ref. 8.
References
1) T. Matsumoto et al.: J. Phys. Chern. Solids 36, 215(1975).
2) J. F. Miller and D. G. Westlake: Trans. Jpn. Int. Met.
21, Suppl., 153 (1980).
3) E. Yagi et al.: Phys. Rev. B 31, 1640 (1985).
4) E. Yagi et al.: Phys. Rev. B 39, 57 (1989).
5) E. Yagi et al.: Proc. Jpn. Academy 65B, 38 (1989).
6) E. Yagi: Radiat. Eff. and Defects Solids 124, 21 (1992).
7) E. Yagi et al.: J. Phys. Soc. Jpn. 54, 1855 (1985).
8) E. Yagi and S. Koike: J. Phys. Soc. Jpn. 67, 340 (1998).

RIKEN Accel. Prog. Rep. 31 (1998)

Annealing of the CU3Au Irradiated with Protons, a-Particles
and C Ions at Liquid Nitrogen Temperature
H. Sakairi,* E. Vagi, and A. Koyama
Ordered alloys are most promising type of systems tostudy the replacement collision iIi damage production
processes and the migration of vacancies, because theireffects are observable as a large change in the orderedstate. Succeeding to the studies on the damage production rate and the isochronal annealing up to 90 K
on the CU3Au irradiated below 30 K with high energy
ions,1 ,2) in the present study the isochronal annealing
experiments were extended up to 460 K. The irradiation was performed for both initially ordered and disordered CU3Au specimens at a temperature below 85
K with protons, a-particles or C ions of various energies from 6 to 90 Me V provided from the Cyclotron
under the condition for incident ions to penetrate thespecimens. Heat treatment for preparing the ordered
specimens followed the previous work. 2) However, theperfect ordering could not be achieved. After each annealing period of 10 min, the electrical resistivity wasmeasured at the liquid N2 temperature. The results
are shown in Fig. 1. Irradiation-introduced defects increase the electrical resistivity. The resistivity increment tJ.p is normalized to the initial resistivity increment tJ.po in the as-irradiated state.

spe-c;imen'" 6 a'4 .iMeV- 9 01 7.7-10 oHi .•

100

200

300

;'00

T(K)

Fig. 1. Isochronal annealing curves of the electrical resistivity for 10 min annealing periods and their temperature derivatives for (a) the initially ordered and (b) initially disordered CU3AU specimens. The inset shows theprevious result obtained for a disordered specimen after
the irradiation with 20.5 MeV a-particles at 13.5 K.

In the ordered specimens two large stages are evident
in the temperature regions 240-340 K and 340-460 K.
Hereafter, these stages are called 290K-stage and the
380K-stage, respectively.
In the disordered specimens three large recovery
stages are observed in the temperature regions 100-220
K (190K-stage), 220- 320 K (280K-stage) and 340-440
K (380K-stage), respectively. The latter two regions
Present address: Sping-8 Service Co. Ltd.

are approximately same as those in the ordered specimens. In addition to these three stages, the recovery curves have an inflection around 150 K, indicating
the presence of a recovery stage (150K-stage). However, with increasing tJ.po, this stage gradually joins
the 190K-stage. Combined with the previous result
shown in the inset of Fig. 1 (b), it can be said that
there exists a recovery stage in the temperature region
between 80 and 110 K (85K-stage).
At the 280K- or 290K-stages and the 380K-stage,in both ordered and disordered alloys, the resistivity becomes lower than the value before irradiation
in some case, indicating an enhancement of the longrange ordering. (The initially ordered specimens were
not perfectly ordered.) Such defect-enhanced ordering has been observed in the experiments of quenchingof the initially disordered or partially ordered CU3Au
from temperatures not only above but also below Tc(the critical temperature for ordering) followed withannealing at temperatures below 473 K. 3- 5 ) Therefore,
the recovery in the two stages in question is considered to be related to the irradiation-introduced vacancies. Considering the results of the positron annihilation experiments,6) the two recovery stages can beinterpreted to be the recovery due to migration of freevacancies to sinks or for the formation of clusters andthe recovery of long-range order associated with it, anddue to migration of the vacancies supplied as a resultof evaporation of vacancy clusters and the associatedordering, respectively.
As for recovery stages above 80 K in the initiallydisordered CU3Au, five stages were observed in theisochronal annealing after the electron irradiation. 7)
Taking account of the incident electron-energy dependence of their five stages,7) the 85K-, 150K- and 190Kstages observed in the present experiments are interpreted to be due to the close-pair recovery of CuFrenkel defects, the migration of Cu interstitials, andthat of Au interstitials, respectively.
References
1) H. Sakairi, E. Vagi, A. Koyama, and R. R. Hasiguti: J.
Phys. Soc. Jpn. 43, 999 (1977).
2) E. Vagi, H. Sakairi, A. Koyama, and R. R. Hasiguti:
Phys. Rev. 38, 3189 (1988).
3) R. A. Dugdale: Phil. Mag. 11, 537 (1956).
4) P. Wright and J. C. Goodchild: Proc. Phys. Soc. 79,
196 (1962).
5) S. Benci, G. Gasparrini, E. Germagnoli, and G.
Schianchi: J. Phys. Chern. Solids 26, 2059 (1965).
6) M. Doyama, P. Moser, D. Huguenin, A. Alamo, and C.
Corbel: Positron Annihilation, ed. P. C. Jain, R. M.
Singru, and K. P. Gopinathan (World Scientific, Singapore, 1985), p. 903.
7) J. Gilbert, H. Herman, and A. C. Damask: Rad. Eff.
20, 37 (1973).
103

RIKEN Accel. Prog. Rep. 31 (1998)

Development of Experimental Setup for Laser Spectroscopic
Study of Ions in Superfluid Helium
Q. Hui and M. Takami
We are preparing a new experiment to implant
atomic ions into superfluid helium (He II) and to measure the laser induced fluorescence (LIF) spectra ofthese ions. Of particular interests are the alkaline earth
ions, i.e. Be+, Mg+, Ca+, Sr+, and Ba+. In the groundstate, each of these ions has only one s-electron outside
its closed ion core. Recent studies in our and othergroups have shown that the neutral atoms with single s-valence electron (group IA and IB atoms in the
periodic table) form metal-Hen exciplexes in the firstexcited P-states in liquid helium. 1 ,2) Because the alkaline earth ions have similar electronic structure as
the group IA and IB atoms, the same phenomenon
is expected to be observed for these ions. The LIF
emissions of the alkaline earth ion-Hen exciplexes are
expected to be in the visible and UV regions, moreconvenient to study than that of alkali atom-Hen exciplexes. Therefore, the alkaline earth ions are an ideal
system to study the dynamics of the exciplex formation process. Furthermore, two light members of theseions, i. e. Be+ and Mg+, may form solid helium shells
surrounding them ("snowballs"), 3) due to strong attractions between these two ions and helium atoms.
If "snowballs" are formed, the LIF excitation spectraof these two ions should show blue-shifts much larger
than the other ions do.
So far, many methods have been used to implantions into liquid helium. We adopt the laser ablation
method which has been proved to be a simple but very
efficient way.4) The experimental setup is illustrated inFig. 1. A metal Dewar (Oxford) equipped with quartz
windows contains He II. A quartz cell is placed above
the liquid and the cell itself is filled also with He II.
Two or three He II pumps, utilizing the "fountain effect" of He II, are used to transfer the liquid into thecell. The surface of the He II in the cell is determinedby the height of the cell. A piece of metal sample ishung about 1 cm above the quartz cell. An ablation
laser beam (1.06 fJ,m, a few mJ/pulse) is focused onto
the sample through one of the windows. A pair ofelectrodes are immersed into the liquid in such a waythat the upper one stays just a few millimeters below
the liquid surface. The upper electrode (extractor) is
typically at + 100 V and the lower one (collector) is
grounded. The sample is at about +200 V. The distance between the extractor and collector is about 1-2
cm. The positively charged ions produced via the laser
ablation are extracted into He II by the electric field. A

104

personal computer

Fig. 1. Illustration of the experimental setup.

pulsed dye laser beam intersects the ion beam between
the extractor and collector and excites the ions. The
LIF emitted by the ions is detected at a right angle bya photomultiplier (PMT) through a monochromator.
The electric signal is averaged by a boxcar integrator
and sent to a computer.
In a preliminary test of the setup, we have observed
Ba+ emission from the plasma produced by the laser
ablation near the sample surface. We find that thisemission becomes weaker a few minutes after the ablation is started due to a change of the surface condition.
This problem can be solved by scanning the ablation
laser beam over the sample surface. Another problem
is the heating of the liquid by the He II pumps whichhave heaters inside. The helium gas pressure in the
Dewar is typically 6 Torr when the pumps are off, andabout 20 Torr when they are on. These pressures correspond to He II temperatures of about 1.6 K and 2
K respectively. Because the mobilities of ions in He
II decrease rapidly with increasing temperature, it isnecessary to keep the temperature as low as possible.
We plan to use two-stage "fountain" pumps with lower
power consumption to solve this problem.
References
1) J. L. Persson et al.: Phys. Rev. Lett. 76, 1501 (1996).
2) J. Dupont-Roc: Z. Phys. B 98, 383 (1995).
3) K. R. Atkins: Phys. Rev. 116, 1339 (1959).
4) G. zu Putlitz and M. R. Beau: in Topics in Applied
Physics 70, Dye Lasers: 25 Years, edited by M. Stuke(Springer-Verlag, Berlin, Heidelberg, 1992), p . 237.

RIKEN Accel. Prog. Rep. 31 (1998)

Muon Spin Relaxation in KCuC1 3
W. Higemoto, H. Tanaka,· 1. Watanabe, and K. Nagamine[J..L+SR, KCuCh, Low Dimensional Magnetism]
Low dimensional magnetism is one of the subjects of
the recent study. In particular, quasi one dimensional
systems have attracted much interests.
We report the results of a positive muon spin relaxation (J..L+SR) experiment on the S = 1/2 double chain
system of KCuCI 3 . Figure 1 illustrates the exchangeinteraction paths in the double chain. The present
system can be described as a S = 1/2 Heisenberg spinladder system consisting of the J 1 and J 2 (or J3 ) interactions with an additional diagonal interaction J 3 (orJ 2 ). Previous magnetic susceptibility measurement 1)
suggests that the ground state of KCuCl3 is a spin singlet state with a finite spin gap of ~/kB rv 35 K. This
spin gap has also been observed in the other measurements.

(a)~~ 0.15
E

~

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0.1

0.05

2

6

4

10

6

6

6
D.

"

6

Q)
CI)

.:;

•

c<

!

•

nI

0::

c::
0

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)(

nI

4

••• • • • • •

6'

8

..

'

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•

. 6

10

a 10

6

Temperotu~K)

I•

0.01

2

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l!.

l!.

•

nI

Qj
0::

D.

•

•

0.1

13I
.

1.5

o z

l!.

....

J..L+SR experiments were carried out at Port-2 of the
RIKEN-RAL Muon Facility. Although, the groundstate of KCuCh is suggested as a spin liquid state, we
observed the fast relaxation below 20 K. Figure 2(a)shows the temperature dependence of the J..L+SR spectra under a longitudinal magnetic field (LF) of 100 G.
Above 20 K, we saw no significant muon spin relaxation, but below 20 K, the muon spin showed fast relaxation. We fit the data with a power-law-type relaxation function, Gz = exp( -(At).B), and the solid lines
in Fig. 2(a) are the results of the fitting. The temperature dependences of the relaxation rate >. and of thepower (3 are shown in Fig. 2(b). Below 20 K, >. increases with decreasing temperature. In LF of 3800 G,
however, we found a cusp in the temperature dependence of the relaxation rate around 5 K.
Our results show the existence of a local magnetic
field of the order of kG at the muon site below 20 K,
while other macroscopic and microscopic experiments

16

0 .5

6

Q)

Fig. 1. The arrangement of the eu atoms of the double
chain and the interactions J 1 , h, and Ja.

14

(b)

-;u

a- axis12

10

8

Time(microsec)•

30

LF 100G
LF 3800G

6

•

~

l!.

30

Temperature(K)Fig. 2. (a): Temperature dependence of the muon spin
relaxation spectra. Solid curves represent the fitting
results. (b): Temperature dependence of the muon spin
relaxation rate >. in LF of 100 G and 3800 G. The inset
figure shows the power (3.
suggest a non-magnetic ground state with a finite spin
gap. Our sample contains very little concentration ofparamagnetic impurities, and thus it is unlikely that
our observed relaxation occurs only due to such an
extrinsic component.
For the investigation of the microscopic muon states,
a muon spin resonance experiment is going on.
References
1) H. Tanaka et al: J. Phys. Soc. Jpn. 65, 1945 (1996).

Department of Physics, Tokyo Institute of Technology

105

RIKEN Accel. Prog. Rep. 31 (1998)

JLSR Studies on (Ndl-ySmy)o.5SrO.5Mn03
W. Higemoto, K. Nishiyama, 1. Watanabe, K. Nagamine,
A. Asamitsu,* H. Kuwahara,* and Y. Tokura*[tt+SR, Manganese Oxide, CMR]
Recent systematic studies on the perovskite typemanganese oxide (Ndl_ySmy)O.5Sro.5Mn031,2) haverevealed a competitive nature existing between the ferromagnetic double-exchange interaction and the antiferromagnetic charge ordering instability which gives
rise to a temperature, magnetic field, and pressure induced transition from the ferromagnetic metal (FM)to antiferromagnetic insulator (AFI). This transition isaccompanied with change of the resistence by several
orders of magnitude, and the phenomenon is known as
the clossal magneto resistence (CMR). The competition between the FM state and AFI state is rather
sensitive to the Mn-O-Mn bond angle or Sm ratioy. In particular, a metastable FM phase appears in
the 0.85 < y < 1 region below 100 K. We have performed the muon spin rotation/relaxation (ttSR) measurements in (Ndl-ySmy)o.5Sro.5Mn03 (y = 0.875) for
the investigation of competition between FM state and
AFI state.
tt+SR experiments were carried out at Port-2 of
RIKEN-RAL Muon Facility (pulsed beam) at the ISIS
Facility of Rutherford Appleton Laboratory in the
U.K. and at M9B decay muon channel of TRIUMF(continuous beam) in Vancouver, Canada. These twomuon beam channels provide us two different typesof muon beam. By using these two beam channels,
we can carry out the experiments covering entire time
resolution as well as time range.
Above 132 K or in the paramagnetic phase, slow
muon spin relaxations were observed under a zero magnetic field (ZF). Figure 1 shows a time evolution of themuon spin asymmetry at 293 K under ZF. The data
can be represented by using an exponential relaxation
function, Pz(t) = Aexp( - At), and the solid line in
Fig. 1 shows the fitted result. In the previous measurement of temperature dependence of the magnetization M in (Ndl-ySmy)O.5Sro.5Mn03, Kuwahara etal. 2 ,3) have observed Curie Weiss-like behavior above
300 K, but clear deviation is evident with a slight upturn from around 200 K to T c in the H/M versus T
curve. Such a deviation was also observed in our tt+SR
experiment. Above 250 K, linear temperature dependence of the muon spin relaxation time was observed,
and below 250 K, a clear deviation from such linearity
was seen.
Figure 2 shows the tt+SR data at 39 K under ZF,
and the solid line in Fig. 2 shows the fitting result obtained by using the relaxation function G z
JRCAT

106

~

293K

~

E 0.15
E

>.

VI

«

"'0

0.1

<U
U

~

~
o
005
U
o

~~~~~~~~~~~~~~~~

o

5

10

15

Time(microsec)
Fig. 1. ZF-I.lSR spectrum at 293 K (paramagnetic phase),taken at RIKEN-RAL Muon Facility.

0.1

~

39K

0.09

~

<U

E

0.08

+

E

+

>. 007
VI

«

3:
ro
a:::

0.06
0.05

0.01

0.02

0.03

0.04

0.05

0.06

0.0 7

0.08

Time( microsec)

Fig. 2. ZF-I.lSR spectrum at 39 K (ferromagnetic phase),taken at TRIUMF.

Li-12 (Ap,i exp( -Ai t ) COS(Wi t + 4» + Ar,i exp( -Ai t )) .
Bel~~ 127 K or in the ferromagnetic phase, we have observed two frequencies of the zero field muon spin precession with temperature independent hyperfine fields.
This means that implanted muon stopped at magnetically inequivalent two sites: probably apical andplaner oxygen sites. Between 132 and 127 K, the signal showed a sudden change from paramagnetic phaseto ferromagnetic phase, and these results clearly show
the first order phase transition.
References
1) Y. Tokura et al.: Phys. Rev. Lett. 76, 3184 (1996).
2) H. Kuwahara et al.: Phys. Rev. B 56, 9386 (1997).
3) H. Kuwahara et al.: Science 272, 80 (1996).

RIKEN Accel. Prog. Rep. 31 (1998)

Critical Spin Dynamics in Ndl-xSrxMnOs with x ~ 0.5
V. V. Krishnamurthy, 1. Watanabe, K. Nagamine, H. Kuwahara,* and Y. Tokura*[CMR, Manganites, Relaxation, Critical phenomena]
Recently, Kuwahara et al. have discovered colossal
magnetoresistence (CMR) at a magnetic field induced
first-order insulator-to-metal phase transition in holedoped perovskite Ndo.5Sro .5Mn03 single crystals. l )The electronic properties and the magnetic groundstate of doped manganites are correlated with the oneelectron bandwidth W which is determined by the radiiof constituent ions. Ndo.5Sro.5Mn03 single crystals
show a paramagnetic-to-ferromagnetic transition at
Tc ~ 251 K and a ferromagnetic-to-antiferromagnetictransition at TN = 158 K. Ndo.45Sro.55Mn03 is a layered A-type antiferromagnet (TN rv 220 K) which exhibits metallic behaviour in the ferromagnetic ally coupled ab-plane ([110]) and exhibits insulating behaviour
along the antiferromagnetically coupled c-axis. Further s.tudies on these magnetic transitions are desirable
for a better understanding of the interplay between themagnetism and magneto-transport in CMR materials.
In this study, we have applied muon spin relaxation(f.L+SR) spectroscopy as a microscopic magnetic probe
to investigate the spin dynamics of Mn ions near magnetic phase transitions by measuring the muon spinlattice relaxation rates A· in the perovskite manganite
Ndl-xSrxMn03 with x = 0.5 and 0.55.
The f.L+SR spectra of Ndl-xSrxMn03 with x = 0.5
and 0.55 measured in zero applied field at different
temperatures between 0.3 and 290 K (see Fig. 1)
were fitted b~ an exponential power law: Pz(t) =Ao exp[-(At) ], where Ao is the muon decay asymmetry at time t = 0, A is the muon spin longitudinal relaxation rate, and f3 is the exponent coefficient.
The relaxation rate A gives a measure of the fluctuating local magnetic fields due to the neighbouring
magnetic ions through dipolar coupling. A is plottedagainst temperature for the x = 0.5 and 0.55 crystals in Fig. 2. The Ao measured in Nd 1 - xSr xMn03(x = 0.5 and 0.55) drops with the decrease of temperature across the second order phase transitions fromparamagnetic to magnetically-ordered state. The measured A in Ndl-xSrxMn03 (x = 0.5 and 0.55) crystals
sensitively probe the spin dynamics at the second order magnetic phase transitions. The absolute values ofmuon spin relaxation rates in Ndl -x SrxMn03 (x = 0.5
and 0.55) (0.12 f.LS-1 at Tc) are smaller compared tothose in LaO.7CaO .3Mn03 (,,-,0.4 f.LS-I at Tc)2) at leastby a factor of "-'4, and indicate that the relaxation
rates decrease with the decrease of the one-electron
bandwidth W.
The temperature dependence of A above T c for
251 K :::; T :::; 290 K is associated with the criticalslowing down of spin fluctuations of Mn moments.
In the inset of Fig. 2 the A is paramaterized by apower law: A(T) <X t W , where t == [(T-Tc)/Tc],
to extract the dynamic critical exponent w. Surpris-

B

a
[

0.15

~

]
~

~

0.05

0.00 o~~~""""""'--'-~~----.Ll0----~~--L..15..J

Time (l1s)Fig. 1. Zero-field J..L+SR time-spectra of Ndo.sSro.sMn03
showing the critical slowing down of local field fluctuations at the paramagnetic-to-ferromagnetic transition
with Tc = 251 K.

0.20

~

"";'

w=O.5

(IJ

::::t.

Ndo.sSro.sMn03

«
C1)

~

...
j

~

Nd 1' XSrxMn03

~

x=O.5

,

Tc -251K
0.10

0.01

s::

.9

0.1

0.05

... •

~OO
0.00

50

:\

0.01
0.1

I

~~

•

8JI~.

100

150

200

250

0

x=O.55300

Temperature (K)Fig. 2. Temperature dependence of >.. measured in
Nd 1 - x Sr x Mn03.

ingly, the critical exponent shows a crossover behaviour
with w = 0.5 for 0.08 :::; t ::; 0.15 and w = 0.24 for
0.015 :::; t :::; 0.08. Such a change in the dynamic critical exponent, which has also been observed in Ni, EuO
and EuS, is associated with a crossover from the exchange critical regime away from T c to the dipolar
critical regime closer to the T c. However, the absolutevalues of ware much smaller compared to the theoretical values of 1.0 and 0.7 of a Heisenberg ferromagnet
at the crossover region. f3 is close to 1 in paramagnetic
phases. In magnetically ordered phases, f3 drops to 0.5
in both x = 0.5 and 0.55 crystals suggesting a stretchedexponential relaxation. We believe that the spin disorder due to hole (Sr) doping may introduce a spreadin the correlations among the localized Mn spins andmay manifest a stretched exponential relaxation.
References
1) H. Kuwahara et al.: Science 270, 961 (1995).
2) R. H. Heffner et al.: Phys. Rev. Lett. 77, 1869 (1996).

JRCAT, Tsukuba

107

RIKEN Accel. Prog. Rep. 31 (1998)

JL+SR Study of Heavy-Fermion Magnetism in Ce(Cul-xNix)2Ge2
V. V. Krishnamurthy, 1. Watanabe, K. Nagamine, C. Geibel,* G. Sparn,* and F. Steglich*[Heavy-fermions, Kondo Lattice, non-Fermi liquid behaviour]
The magnetic behaviour of heavy-fermion (HF) systems at the crossover from the RKKY-interaction dominated magnetic regime to the pure Kondo region is a
topic of current interest. Recently, the quasiternary
HF system Ce(Cu1-xNixhGe2 is reported to exhibit
an interesting magnetic phase diagram, determined by
the DC susceptibility (XDC) and specific heat measurements, consisting of local moment antiferromagnetism(TN = 4.1 K) for 0 ~ x ::; 0.1 and HF band magnetism for 0.2 ::; x < 0.75. 1) Neutron diffraction (ND)
studies showed a static spin wave for x = 0.285, but
magnetic reflections could not be observed for x 2:: 0.5.
Further, non-Fermi liquid behaviour (NFL) may appear for x 2:: 0.8 due to the suppression of TN to 0
K. Buettgen et ai. have observed a logarithmic scalingof spin-lattice relaxation rate 11T1 measured by NMR
at 63Cu in Ce(Cuo.2Nio.8hGe2.2) In the present study,
we have applied the muon spin relaxation (J..t+SR) spectroscopy to the Ce(Cu1-xNixhGe2 system to investigate the occurrence of long range magnetic ordering,
the size of the ordered moment at x = 0.5, and theNFL behaviour at x = 0.8.
The zero-field (ZF) J..t+SR spectra of polycrystalline
Ce(Cuo.5Nio.5hGe2 for T 2:: 4 K are fitted by astreched exponential relaxation function, of the form:G z (t) = Ao exp[-(>.t)i3j + A bg
(1)
where Ao is the initial asymmetry, A is the muon spin
relaxation rate and Abg is a constant background. A remains constant at 0.032 J..ts- 1 , and the exponent f3 also
remains constant at 1.50(25) for temperatures above
4.0 K. The ZF spectra, which show a fast relaxing component in addition to the slowly relaxing one between
3.4 and 4 K, could be described by the functional form:Gz(t) = Aoe [-(A S !ot).8S] + Ale[-(Af stt )i3 f ] + A bg •(2)

The first and second terms describe the slow relaxation
component and the fast relaxation one observed in thefirst 1 J..ts, respectively. The asymmetry of the slowly
relaxing component Ao starts to decrease sharply at
3.97 K (see Fig. 1). A constant fraction of 2/5 is lostfor T < 3.4 K. These features are consistent with themagnclic transition inferred from XDC measurements.
From the temperature dependence of asymmetry Ao,
we could extract the Neel temperature TN as 4.0 K,
which is consistent with the appearance of cusp in
XDC·
Temperature dependences of Af st, Aslo and A are displayed in Fig. 2. Best fits to Eq. (2) yielded f3s = 1
and f3 f = 2. f3s = 1 is consistent with the 41 spin fluctuations which are longitudinal to initial muon spinpolarization. Gaussian (f3f = 2) relaxation of the fast
IFKP, Techniche Hochschule Datmstadt, Germany

108

0.32

•

b' 0.28
Q)

a
a>.

~

Ce(Cuo.sNio.S}2Ge2

0.24
0.20

1

10
Temperature (K)100Fig. 1. Temperature dependence of the initial asymmetry
Ao measured in Ce(Cuo.5Nio.5hGe2.

.;:""'

~

10'

«

.sas

~

c

..3
as
><
as

"@
~

",1
10.3 1~.

\

4:

Ce(Cuo.sNio.S>2Ge2

•

I

10

~J
100

Temperature (K)Fig. 2. Temperature dependence of the muon spin relaxation rate A in Ce(Cuo.5 Nio.5hGe2 in zero appliedfield.

component suggests the distribution of static internal
fields at the muon site. The decoupling of t.he asymmetry lost in magnetically ordered state at 2 K could be
described by assuming a single muon site yielding thestatic internal field at the muon site, Bp. = 0.49(6) kG.
We have also searched for the possible non-Fermi
liquid behaviour in Ce(Cuo.2Nio.8hGe2. The zero field
J..t+SR spectra measured at temperatures between 2 K
and 200 K are also represented by Eq. (1) with a temperature independent relaxation rate of 0.05 J..ts- 1 anda temperature dependent exponent /3 which gradually
increases from 1.25 at 200 K to 1.75 at 2 K. Therefore, we do not observe the logarithmic scaling of muon
spin relaxation rates A with temperature, in contrast to
63Cu NMR results. A likely reason for the discrepancy
between J..t+SR and 63Cu NMR measurements could
be that 41 spin fluctuations of Ce in the paramagnetic
phase are too slow, as indicated by the values of 63Cu
NMR relaxation rates 1 IT 1 (rv S - 1), to be observablein the J..tsec time scale of J..t+SR. Long range magnetic
ordering is not observed either down to 2 K.
References
1) Loidl et al.: Ann. Physik 1, 78 (1992).
2) Buettgen et al.: Phys. Rev. B 53, 5557 (1996).

RIKEN Accel. Prog. Rep. 31 (1998)

J,LSR Studies of Non-Fermi-Liquid Behaviour in Ce7Ni3
T. Takabatake,*l K. Umeo,*l R. Kadono, 1. Watanabe, G. M. Kalvius,*2 and A. Kratzer*2
A heavy fermion compound, Ce7Ni3, shows nonFermi-liquid behaviour when an antiferromagnetic ordering is destroyed under the pressure of 4 kbar. 1 )However, nature of the magnetic transition even at
the ambient pressure is complicated due to the presence of three nonequivalent Ce sites in the crystal. The
crystal structure of Ce7Ni3 is the hexagonal Th7Fe3type structure as shown in Fig. 1, where the three sites
are named as Cel, Cell, and CellI. The ratio of each
Ce site in these sub-lattices is 1:3:3. Recent neutron
diffraction study by Motoya et al. 2) has shown that
only CeI and Cell have formed the spin-density-wave(SDW) state below TN = 1.8 K.

0.22~.:: 0.21
~

~

D.2

~

-< 0.19
3 O.IBQ

E-4 0.17

ID

0.18

m
m
II

0.15

ID

I

I

I

2

"5

7

9

10

Temperature (K)Fig. 2. Temperature dependence of ZF-J.LSR asymmetry
parameter. The base line was determined from transverse field experiments.

a .. -----~___...:!~_ (IFig. 1. Crystal structure of Ce7 Nb. The atoms 1-4 are
CeI, Cell, CellI, and Ni, respectively.

In order to study the magnetic state in Ce7 Ni3 froma microscopic point of view, we have performed f.l+SR
experiments on a single-crystal sample at RIKEN-RAL
Muon Facility in the UK. A pulsed positive muon beam
was injected parallel to the hexagonal c axis. The
sample was cooled down to 0.3 K by using a 3Hecryostat. The single crystal was prepared by the RFheated Czochralski method at Hiroshima University.
In a zero field (ZF), the I1SR time spectra at 10
K showed depolarization behaviour. This suggeststhat dynamical magnetic correlations develop from far
above TN. Below TN, about 30% of the asymmetryof a muon spin decreases as shown in Fig. 2. Thischange in the asymmetry means the existence of a fast
depolarization component which can not be resolved
within a time resolution of the present I1+SR experiment. Such a fast depolarization can be caused by abroad field distribution due to static moments in an
incommensurate SDW state. Remaining part of theasymmetry includes two components. One was decoupled in a longitudinal field of about 100 G, whereas*1*2

the other was not affected even by 3800 G. The lattermust be of a dynamical origin, since its depolarization
rate of 2.5 I1S-1 would correspond to a static width of
only 30 G which should be decoupled by about 200 G
if the origin is static.
In order to understand these findings, we have toknow the muon sites in Ce7 Ni 3. At present, there is
no experimental result on the muon site. But results ofthe electrostatic potential calculations are available. 3)
According to these calculations, there are two possible muon sites, site-A and site-B. Site-A is surroundedby six Cell atoms, and site B by one Cel atom andthree CellI atoms. Possible interpretation of our data
is as follows. The 30% loss of the asymmetry below
TN originates from the muons at site-A. This is dueto the SDW order of Cell moments. Remaining signal
comes from the muons at site-B. The depolarization
has both the fast relaxation and slow relaxation components. The former is the dynamic part due to theparamagnetic CellI moments, while the latter is thestatic part due to the ordered Cel moments. In order
to confirm this interpretation, we will perform experiments in different beam orientations with respect tothe crystal axis in near future.
References
1) K. Umeo, H. Kadomatsu, and T. Takabatake: J. Phys.:
Condo Matt. 8, 9743 (1996).
2) K. Motoya: private communication.
3) D. Noakes: private communication.

Department of Materials Science, Hiroshima University
Physics Department, TU Munich

109

RIKEN Accel. Prog. Rep. 31 (1998)

Behavior of the Positive Muon in 2H-NhSe2
W. Higemoto, K. Nagamine, S. Kuroda,* and K. Takita*[j.L+SR, CDW, Superconductivity]
Behavior of the positive muon in the transition
metal dicalcogenide 2H-NbSe2 was studied by a zero
field muon spin relaxation (ZF-j.L+SR) technique. 2HNbSe2 is known to exhibit two phase transitions. One
is the Charge Density Wave (CDW) transition at 32 K
and another is the superconducting transition at 7 K
in which CDW state coexists. 1) Both transitions are
related to the change of the electronic states near the
Fermi surface. It is known that the hopping motion
or quantum tunneling of muons in metal is related tothe conduction electrons 2) through the electron-drageffect, and muon diffusion phenomenon is one of theimportant subjects. We are investigating the relation
between the muon behavior and CDW state or superconducting state in 2H-NbSe2 ' At the same time, thetransition metal dicalcogenide compound is known tobe able to intercalate the molecules or atoms into theinterlayer. In 2H-NbSe2' muon is expected to behave
as one kind of the intercalants, and its behavior is alsointeresting from the view of the intercalation phenomena.
ZF-j.L+SR experiment was carried out at Port 2 of the
RIKEN-RAL Muon Facility. We found that the muon
spin relaxation phenomena under ZF can be divided
into four temperature regions from the characteristicfeatures of the j.LSR spectra. Figure 1 shows the typical ZF-j.L+SR spectra in 2H-NbSe2 in each temperature
region. At 293 K, about half of the implanted muons(called fast component) showed a Kubo-Toyabe-typespin relaxation, and the rest of the muons (called slow
component) took a very slow spin relaxation. At 110 K(not shown here), we found that the ratio of fractionof these two components and its hopping rates change,as seen for 63.8 K data in Fig. 1. Such changes of themuon states are also observed at 32 K (CDW transition temperature) and 7 K (superconducting transition temperature). These facts clearly show that muon

Institute of Materials Science, University of Tsukuba

110

2H-NbSe2

o

5

10

15

20

Time(microsec)
Fig. 1. ZF-j.LSR spectra at 293, 63.8, 8.9 (CDW phase)and 5.0 K (CDW and superconducting phases).

states are affected by the CDW and superconducting
states. The change of the j.LSR spectra found at 110 K
might be showing a new phase transition.
Microscopic muon state is very impotant for thej.L+SR study of matter. Our result is considered asa new feature of the muon behavior, and further investigation is in progress.
References
1) R. Sooryakumar and M. V. Klein: Phys. Rev. Lett. 45,
660 (1980).
2) For example, R. Kadono et al.: Phys. Rev. B 39, 23(1989).

RIKEN Accel. Prog. Rep. 31 (1998)

p,SR Study on 2D Kagome Organic Magnet, rn-MPYNNBF 4
1. Watanabe, N. Wada,· H. Yano,· A. Yamaguchi,· K. Awaga,·
S. Ohira, K. Nishiyama, and K . Nagamine
Ground state of 2D Kagome magnet, in whichmagnetic moments on Kagome latteices are coupledthrough an antiferromagnetic (AF) interaction, is ofinterest from a view point of a frustrated system.
The organic antiferromagnet (AFM), m-MPYNNBF 4,
comprises magnetic layers of an a-nitronyl nitrooxide
cation allylradical with S = 1/2. 1 ) The radical makes
a dimer state with S = 1 through a strong intermolecular ferromagnetic interaction, and the dimer
couples antiferromagnetically each other through theinter-dimer AF interaction as shown in Fig. 1. 2 ) The
system has been suggested from a susceptibility measurement to show a spin gap state below 240 mK witha non-magnetic ground state. 2 ) If the spin gap state isconfirmed in this system, it could be the first example
in 2D systems.

1.0

rn-MPYNNBF4

ZF

]

1
z

0

..
10

15

t (Ilsec)

Fig. 2. ZF-p'sR time spectra.
1.5

rn-MPYNNBF4
30rnK

£
El

LF= IOOG

lOG

1.0

~

-<
~

0.5

~
0

Z
5G

o

10

15

t (Ilsec )2!o//m=23.3K

Fig. 3. Longitudinal-field (LF) dependence of the J.LSR
time spectrum at 30 mK.

Fig. 1. Model of a crystal structure of m- MPYNNBF 4.
Zero-field (ZF) and longitudinal-field (LF) muon
spin relaxation (p'sR) measurements have been carriedout on a single crystal of m- MPYMMNF 4 down to 30
mK to study the ground state of the system. 3 ) The
measurements were performed at KEK-MSL by using
a top-loading dilution refrigerator and an ordinary gas
flow cryostat.
Figure 2 shows the ZF -p'sR time spectra obtained
at 265, 100, 2.9 K and 30 mK. The spectrum at eachtemperature was normalized at t = 0 to compare thedifference among various time spectra. Any strong enhancement of the critical slow down of the dimer spin
was not observed. Dynamical and static properties ofthe dimer spin is expected to be almost temperature
independent. The motional narrowing effect due to the
diffusion of the muon can be observed at the temperature higher than about 200 K.
Figure 3 shows the LF dependence of the time spectrum at 30 mK. The decoupling behavior by the LF
was observed. The spectra were analyzed by using the
dynamical Kubo-Toyabe function. A half width of thestatically distributed component of the internal field
was about 10 G. The muon spin is depolarized also by
the dynamical fluctuating component of the internal
Graduate School of Arts and Science, Univ. of Tokyo

field with the depolarization rate of about 0.5 /-lsec- 1 .
It is known that the implanted muon in a crystal which contains F- ion forms a strong F /-IF statethrough a hydrogen bonding. 4 ) In this case, the distance between the F- ion and the muon is about anominal radius 1.16 A of the F- ion. If the muon
which was implanted in m-MPYNNBF 4 makes such ahydrogen bonding with the F- ion, the nuclear dipole
field of the nearest 19F is estimated to be about 8.5
G at the muon site. This value is comparable to theinternal static field distribution at muon sites that was
obtained from the present /-lSR study. No other additional field which is expected to be accompanied witha magnetic ordering of the dimer spins was observed.
Therefore, it can be concluded that no clear magnetic ordering of the dimer spins can not be expected
for the dimer spins, and that the ground state of mMPYNNBF 4 is non-magnetic. This result supports
the spin gap feature of this system which has beensuggested by the susceptibility measurement. 2)
References1} K. Awaga et al.: Phys. Rev. B 49, 3975 (1993).
2} N. Wada et al.: J. Soc. Phys. Jpn. 66, 961 (1997).
3} I. Watanabe et al.: in preparation.
4} J. H. Brewer et al.: Phys. Rev. B 33, 7813 (1986).
111

RIKEN Accel. Prog. Rep. 31 (1998)

jlSR Study of Critical Behavior of p-CI-C 6 H 4 -CH==N-TEMPO
S. Ohira, 1. Watanabe, T . Ishida,* T. Nogami,* and K. Nagamine
Organic radical ferromagnets having 2, 2, 6, 6tetramethylpiperidin-l-yloxyl (TEMPO) group form
2D zig-zag networks of N-O radicals in the crystal. The
stable radicals contribute to their magnetism whichis considered to reflect their zig-zag sheet structure. 1)
One of them, p-CI-C 6 H4-CH=N- TEMPO, has beensuggested from an ac susceptibility to show a ferromagnetic transition. 2 ) Our previous muon spin relaxation(p'sR) measurement revealed clear oscillations of muon
spins below 0.28 K, where the susceptibility showed apeak in its temperature dependence; indicating the existence of a bulk ferromagnetic ordered state. 3 ) Fromthese results, some magnetic ordering seems to start
below 0.4 K, where a divergence of the ac susceptibility starts. In order to clarify the magnetic state in
the temperature range of 0.28-0.4 K, we have carriedout the zero field (ZF) and longitudinal field (LF) ~SR
measurements on a single crystal of p-CI-C 6 H 4 -CH= NTEMPO down to 0.30 K.
The measurements were carried out at RIKEN-RAL
Muon Facility by using a 3He cryostat. Figure 1 shows
the ZF-~SR time spectra. The enhancement of relaxation rate due to a critical slow down effect is observable at rvO.3 K. Furthermore, an internal field at themuon site also increases rapidly as temperature approaches to 0.3 K (Fig. 2); indicating that a random
static internal field due to radical spins appears at themuon site above the transition temperature observedin the previous ~SR study.
• 1•.---..---.----.,-----.,-----~~

O -o-CH~ N

. 12

c

. 1

~ .08
E .06
i;;'
<l:

O. 4 0K-Q

N- O·' ' ' ' ' - - O.36K

.0 4

. 02

Time ( micr os ec )Fig. 1. Temperature dependence of ZF -J..tSR spectra.
The existence of the random static field due to radical spins was also confirmed by the LF experiment.
Figure 3 shows the LF-~SR spectra at 0.30 K. The
time spectra below LF = 200 G can be analyzed by the
LF Kubo- Toyabe function. Muon spin depolarization
due to the random dipole field of the radical spins was
decoupled under LF of about 300 G. This value corresponds to the internal field of about 30 G,4) which
is obviously larger than the nuclear dipole field. This
University of Electro-Communications

112

36

0.25

34
0.20

2:
-u

a;
cZ

to

.,
3

)I()I(32

Q))l( JII

0 . 15jill!:

30

E

)I(

)I(

OJ

e::

)I(

I

.::

ell

.~

0 . 10

-:;;

Q)

5

26

><

~

OJ

1D9!l

ID
ell

26
0 .2

0 .4

al

g?
0 .6

a;
e::

0 .05

~
0.8

1. 0

0.00

Temper a t u r e [K]Fig. 2. Temperature dependences of fitting parameters.
Increases of the relaxation rate and field distribution,with decreasing temperature, correspond to a criticalslow down effect and to an appearance of a random
field due to radical spins , respectively.

C . 08
Q;

E .06

•

>-

I/)

<l: .0 4
.0 2

.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Time (microsec)

Fig. 3. Longitudinal field (LF) decoupling at 0.30 K. The
time spectra under the LF less than ",200 G are wellfitted by the LF Kubo-Toyabe function .
component appeared below 0.40 K , at which temperature divergence of t he ac susceptibility starts. 2 ) On theother hand , only the dynamical relaxations caused bya muonium formation were observed above 0.40 K.
Because this system has a strong two-dimensionality
in the magnetic interaction, the magnetic ordering is
expected to start in the sheet of the N-O radicals .
Therefore, our ~SR result shows t hat not only the spin
fluct uation is suppressed, but also the random static
field due to the radical spins appears, in the sheet below 0.40 K. The static field observed above 0.30 K
originates from a magnetic ordering state quite different from that observed below 0.28 K; it may be caused
by a fract ionally occurred short-range ordering due toan intra-sheet ferromagnetic interaction. From the ac
susceptibility and ~SR measurements, a crossover from
2D to 3D ordering is suggested.
References
1) T. Nogami et al.: Synth. Met. 71, 1813 (1995).
2) T. Nogami et al.: Chern. Lett . 1995, 635.
3) R. Imachi et al. : Chern. Lett. 1997, 233.
4) Y. J . Demura et al.: Phys. Rev. B 31 , 546 (1985).

RIKEN Accel. Prog. Rep. 31 (1998)

JL+SR Study of Polaron Motion in Polyaniline t
F. L. Pratt, K. Ishida, K. Nagamine, S. J. Blundell,*l W. Hayes,*l and A. P. Monkman*2
Polyaniline (PANI) is one of a number of conducting
polymers that have been attracting considerable attention recently due to the high conductivities achievableby doping and due to their potential as highly tailorable semiconducting materials for use in electronics
and optoelectronics. Understanding the mechanismsof polaron motion in such materials is of great importance, both for fundamental and technological reasons. However, the transport mechanisms and theirrelation to the underlying polymer structure and themodifications produced by doping are still poorly understood. One reason for this is that macroscopic electronic transport measurements such as conductivity
are dominated by the slowest component of the transport process, which is strongly dependent on the degreeof order in the sample morphology. On the other hand,microscopic dynamical probes such as ESR, NMR and
J.LSR are much better placed to focus at the local levelon the intrinsic transport processes governing the mobility of an electronic excitation travelling along a polymer chain. ESR and NMR work best for the doped
case, since the motional linewidth contributions areproportional to the carrier density. In contrast, thepositive muon is a uniquely sensitive microscopic probeof polaron excitations in the undoped state of a conducting polymer, as the muon implantation processitself generates an excitation which is initially close to
the muon site (See Fig. 1). The dynamical propertiesof this muon-generated excitation can then be studied
via the muon relaxation.

which is centred on a quinoid ring (Fig. 1). After creation, the polaron can easily move away from its initialsite and diffuse up and down the polymer chain at the
intrachain diffusion rate D II , with occasional hops toadjacent chains controlled by the inter-chain diffusion
rate D..l. The measured muon relaxation data werefitted using a theory for a muon interacting with arapidly diffusing electronic spin defect. In the regimeof fast ID diffusion, the relaxation parameter r has aninverse magnetic field dependence, which allows estimation of D II . As the field is reduced there will be a
cut-off to the inverse field dependence of r due to acrossover to a 3D diffusion regime, which occurs when
the polaron Larmor frequency becomes smaller thanD..l. This crossover can be used to estimate D..l.
The temperature dependences of the diffusion rates
DII and D..l are shown in Fig. 2. DII shows a weakmetallic temperature coefficient at low temperaturesthat becomes rather stronger above 150 K. Between
150 and 200 K the diffusion rate is inversely proportional to temperature, which is suggestive of phonon
limited transport. A fall in DII (increase in r) occurs
above 150 K. We associate this with polaron scatteringby phenyl ring librations, which couple strongly to theelectronic excitations. In contrast to D II , it can be seenthat the interchain diffusion D..l shows an activatedsemiconducting behaviour and it increases sharply inthe region above 150 K where DII is decreasing withtemperature. This strongly suggests that the ring rotation is assisting the interchain transport, whereas it
hinders the metal-like intrachain motion.

HjQ(~~NON~N'~O(
I

H
H

jQ(~~N~N~NN® --~Fig. 1. Polyaniline chemical structure and the mobile
negative polaron created by addition of muonium tothe polymer.
As in other unsaturated organic systems, the muon
picks up an electron to form muonium as it slows
down in the polymer. This muonium then reacts
with the polymer, resulting in the muon analogue ofa hydrogenation reaction (Fig. 1), which corresponds
to adding a single electron to the lowest unoccupied
molecular orbital (LUMO) of the polymer. Following rapid electronic and structural relaxation of thesurrounding polymer, a negative polaron is formed,*1*2

Condensed from the article in Phys. Rev. Lett. 79, 2855
(1997) .
Department of Physics, University of Oxford
Department of Physics, University of Durham

~
c

.~

10'

0.1

@

o

10'

+
10

100

Temperature (K)Fig. 2. Intra-chain (D II ) and inter-chain (Dl.) polaron diffusion rates deduced from the muon relaxation in PAN!.
One important difference between P ANI and thesimplest conducting polymer polyacetylene is the lackof charge conjugation symmetry in the former. This
produces a dramatic difference between the mobilitiesof positive and negative polarons. The negative polaron is relatively mobile, whereas movement of a positive polaron requires large ring rotations, making itmuch more massive and immobile. Protonation produces positive polarons and previous diffusion studiesof these positive polarons using ESR have shown anactivated DII below 150 K, in stark contrast to themetal-like behaviour seen here.
113 .

RIKEN Accel. Prog. Rep. 31 (1998)

Muon Studies on the Weak Charge Transfer System
Anthracene / Tetracyano benzene
R. M. Macrae, R. Kadono, K. Nagamine, and J. U. von Schiitz*
Binary complexes produced by co-crystallisation of
two planar aromatic compounds with moderately different electron affinities have a charge-neutral groundstate but display a degree of charge transfer behaviourin their electronically excited states. 1) Donor-acceptor
alternation in the lattice leads to increased librational
freedom, resulting in molecular reorientational dynamics and order-disorder phase transitions. Additionally,
triplet excitons produced by 8 1 +-80 excitation in thesesystems have a high degree of mability in the lattice,with hop dimensionality partially controlled by the degree of charge transfer in the Tl state. Muon spin rotation offers the possibility of simultaneous study ofthese two phenomena, using the free radicals generated by muonium addition to probe the behaviour microscopically through orientational averaging and electronic relaxation processes affecting the muon-electron
hyperfine interaction. 2 ,3)The first studies were carried out on anthracene/tetracyanobenzene, which shows a phase transition at
207 K related to averaging of the anthracene molecules
between two symmetrically-related local minima andhas largely in-stack exciton transport. 1) The possible
muonium adducts to A and TeNB are shown in Fig. I.
ALC-pBR studies at PSI revealed the presence of atleast four radicals, with ~M = 1 resonances at 7436,
8442, 11509, and 13800 G respectively, corresponding
to Ap, = 203, 230, 316, and 368 MHz. In order to assign
these signals, ab initio calculations were carried out at
RIKEN using Gaussian 94. 4 ) The isotropic (Fermi contact) parameter was computed using the UHF and UBPW91 approximations, using the basis sets 6-31G and
6-31G(d,p) respectively. The results are displayed inTable 1. The disagreement between techniques is a result of spin contamination in the UHF wavefunction:
the UB-PW91 values are likely to be more reliable.
The strong signals at 7436 and 11509 G are tentatively
assigned to A3 and AI. The smaller signal at 8442 G
may be from a minority crystallographic A3 site or
may point to a misassignment of AI, while the weak

Table 1. Calculated isotropic hyperfine parameters for M u
adducts to A and TCNB.
Radical
Al
A2
A3
A4

AIL/MHzUHF UBPW
427
242
465
291
369
167
697
930

AJ.L/ MHzUHF UBPW
513
396
468
319
691
351
654

Radical
Tl
T2
T3
T4

line at 13800 G may be due to T3, the most stable
TCNB adduct.
Preliminary studies were carried out at RIKEN-RAL
towards the observation of reorientational dynamics bytime-dependent LF p,SR spectroscopy. A temperaturescan at 250 G revealed a discontinuity in the total
time-zero asymmetry at 210 K, with about 20% of thefull asymmetry missing above this temperature (seeFig. 2). This is consistent with a relaxation process affecting the muonium precursor state, possibly a resultof a longer Mu lifetime in thevibrationally-averaged
lattice. Future work will involve direct 8 1 +-80 laser
irradiation synchronous with the J..L+ implantation inorder to study interactions between the mobile Tl state
and the probe radicals.

I~([)ttl I

CD

150

100

1150

200

2150

300

Temperature/K

Fig. 2. ARGUS results for A/TCNB: total initial asymmetry against temperature at B = 250 G.

References

Fig. 1. Possible Mu addition sites to A and TCNB.
3. Physikalisches Institut, Universitiit Stuttgart, Germany

1141) J. Krzystek and J. U. von Schutz: Adv. Chern. Phys.
LXXVI, 167 (1993), and refs. within.
2) See for example E. Roduner et al.: Chern. Phys. 192,
231 (1995).
3) S. F. J. Cox and D. S. Sivia: Appl. Magn. Reson. 12,
213 (1997).
4) Gaussian 94 (revision A.l), M. J. Frisch et a1.: GaussianInc., Pittsburgh PA, 1995.

RIKEN Accel. Prog. Rep. 31 (1998)

Electronic State of JLAI Pseudo-Acceptor Centers
in Si Probed by J.L-SR
R. Kadono, F. L. Pratt, 1. Watanabe, and K. Nagamine
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,l) which has been a serious obstacle to the study of electronic structure ofactive centers. The implanted negative muon forms aspin-polarized acceptor center and thereby the negative muon spin rotation (p,-SR) may serve as a complementary technique to provide microscopic information. Recently, a couple of p, - SR results in crystalline
silicon were reported,2,3) although there remains somedisagreement with each other. In this short note wereport our preliminary results of p, - SR study in crystalline silicon.
The experiment was conducted at the port-2 channel of the RIKEN-RAL Muon Facility. A negative
muon beam with a momentum of 50 Me V / c was implanted into the sample consisting of 10 intrinsic c-Si
wafers in stack ([111], resistivity ~ 2.2 kncm, total ",3mm thick) and time-differential TF-p,SR spectra wereobtained by the ARGUS spectrometer. 4 ) The appliedmagnetic field was 4.0 mT, which is considerably lower
than those reported in Refs. 2, 3 (see below). The longlived background rate was such that the electrons fromp,-Si muonic atoms (lifetime'" 0.8 p,s) were clearly observed over 6 p,s range.
Figure 1 shows the observed electron decay asymmetry of p,-Si (=J-LAl, which is diamagnetic as inferredby the frequency) 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. 2 and strongly
suggests the paramagnetic precursor state undergoing
fast relaxation. The change of asymmetry observed
at 4.0 (this work) and 40 mT2) is absent at 80 mT,3)
thereby suggesting that the hyperfine field for the pre-cursor state may be 101.5 mT.
The hyperfine parameter is more precisely determined by measuring the field-dependent recovery of
the asymmetry under a longitudinal field B (i.e., LFrepolarization). The data at 10 K are shown in Fig. 2,
where the solid curve is a fit assuming the isotropic hyperfine parameter Wo between J-LAI spin and the outermost shell electrons so that the polarization is given by(1)

where x = IJ-LB/wo, v is the spin/charge exchange interaction rate for the paramagnetic precursor state,
and K, is the rate of transition to the final diamagnetic
state. 5 ) The same model also applies to the TF data
in Fig. 1 with an appropriate temperature dependence
for K,:
P

xy (

-1)

t »wo

2+4(K:/WO)2(l+2v/K:)2= 3 + 2V/K: + 4(K:/wO)2(l + 2v/K:)2'

(2)

(3)
= K:O exp( -Ea./kBT).
The fitting analysis yields the hyperfine parameterwo/27f = 2.80(61) GHz.
The value is considerably
smaller than that for the interstitial center (Le., 16.13
GHz scaled from EPR result) and suggesting the substitutional center (J-LAIO).6) Detailed theoretical calculation is now in progress.
K:.025 ,--------r-----r-- -- . - - - - ,

10K
.02

>-

0:::

ti0 15~~in .01«.005

o/"A I in Si

o

.1

.2

.3

.4

FIELD (T)Fig. 2. LF-repolarization of the p.-e decay asymmetry inc-Si at 10 K .

.025

>-

.02

References0:::

ti .015
~

~

.01

Vl

« .005o- .005 L.....J.....t...J....L.I...J...-_-'---'---'--'-.t...J....L..L.I...-_...L..-...J4 5 7 920 30 5070 100
200300TEMPERATURE (K)Fig. 1. TF-p.SR asymmetry of the J.LAI acceptor centersin c-Si. Solid curve is a fit with the model described in
the text.

1) See, for example, G. W. Ludwig and H. H. Woodbury:
Electron Spin Resonance in Semiconductors (Academic
Press Inc., New York, 1962).
2) M. Koch et al.: Hyperfine Interact. 65, 1039 (1990).
3) T. N. Mamedov et al.: Hyperfine Interactions 86, 717(1994).
4) R. Kadono et al.: RIKEN Accel. Prog. Rep. 29, 196(1995).
5) 1. G. Ivanter and V. P. Smilga: Zh. Eksp. Teor. Fiz. 55,
1521 (1968) [Sov. Phys. JETP 28, 796 (1969)].
6) T.M. Briere: private communication.
115

RIKEN Accel. Prog. Rep. 31 (1998)

Development of an RF Resonance System for Pulsed
Muon Beam Method at RIKEN-RAL
1. Watanabe and K. Nagamine

Muon spin resonance (p,SR) method using a radio
frequency (RF) field in a strong longitudinal field (LF)
is a good microscopic method to investigate hyperfine
interactions, static distributions, and dynamics of a
local field at a muon site in magnetic materials. 1,2)
One of strong advantages of the RF-p,SR is that thehyperfine field at the muon site can be obtained ina decoupled condition. Therefore, a final muon state
after some chemical reaction processes in which a muon
spin polarization is lost by dephasing can be measured,
because the time dependence of the muon state canbe obtained by changing the times of RF triggering.
The other advantage is that the spin susceptibility ofmagnetic moments at the muon site can be obtained.
In order to generate the RF field of a couple of ten
Gauss perpendicular to the LF, the peak RF power
close to 100 kW has to be applied; so that a muon
spin can complete its transition within the lifetime ofmuon. Such a strong RF field can only be achieved
with a low duty factor. In the case of a pulsed muon
beam, the RF field can be synchronized with a burstof the muon beam pulse and is applied for at most 30
p,sec of the p,SR time range compared to the lifetimeof muon (2.2 p,sec). Since a short RF pulse results ina low duty factor , a high peak power of the RF field
can be realized.
RF resonance techniques with pulsed muon beam
have been established at KEK/MSL. 2) Because a lot ofdata points are needed to determine one resonance frequency at a fixed temperature, an intense muon beam
is essential for the accuracy of data and for the efficiency of data acquisition. Therefore, an intense pulsed
muon beam at RIKEN-RAL Muon Facility too is very
favorable for the RF-J,.£SR experiments. We report here
the development works of an RF resonance system at
RIKEN-RAL Muon Facility.
Figure 1 shows an electric circuit diagram of thepresent RF resonance system. We chose a highimpedance matching system in which two variable capacitors are used to achieve a good transmission of the
RF power. Advantages of this system are that a reflection of the RF power can be minimized while a high-Q
value of the system can be achieved due to a small L-C
tank circuit.
Figure 2 shows a test probe of the RF system. The
designed frequency range is from 30 to 60 MHz. The
coil with a target specimen can be cooled down to 1.5
K by using an existing gas-flow type cryostat. Twovariable capacitors were made by ceramics. An electrode made of Cu-foil was wound around on a surface of the ceramic tube. An inner electrode can be

116

Transmission Line
50 n Co-axial

Tank Circuit

Fig.
1.
Electric circuit diagram of the developed
RF-resonance system .

Fig. 2. The RF system testing probe made by the author.

moved mechanically up and down to vary the capacitance. A maximum capacitance was about 100 pF forthe matching capacitor and about 50 pF for the tankcircuit capacitor. A sample coil was fabricated fromthe Cu foil with thickness of 10 p,m and was woundaround on an insulating coil holder. The coil width
was 2 mm. A thin coil is important for the surface
muon to pass through the coil. The coil aperture was
30 mm x 6 mm with length of 40 mm, which was large
enough to put p,SR samples in it. The measured Qvalue of the system ranged from 30 to 40.
Figure 3 shows a wide-band pulsed RF amplifier(AMT, Model-3445). The maximum output power is 2
kW and gain 66 dB. For easy maintenance, we chose an
air-cooled solid-state amplifier which uses transistors
to amplify the pulsed RF. Because the high-Q system
was chosen, we did not need a high power RF source toFig. 3. Wide-band pulsed RF power amplifier AMT
Model-3445, whose maximum output is 2 kW.
achieve the strong RF field. The RF power is transmitted to the tank circuit through a 50 n co-axial cable.
By using this test probe, we applied the RF resonance technique to investigate magnetic properties ofan insulating oxide, LaCo03, as a demonstration of thedeveloped RF resonance system performance. Background physics of this oxide are already reported ina separate contribution. 3 ) The adopted RF frequency
was 40.000 MHZ. The pulse width was about 30 p,sec
with a repetition rate of 50 Hz, so that the duty factor
was 0.15%. The rising time of the RF field was about
250 nsec, which was fast enough for the RF-p,SR. The
output power was 150 W.
Figure 4 shows obtained typical RF-p,SR time spectra. At the time of resonance, the precession frequency
around the RF field is minimized, but the precession

LaCo03300K++

amplitude is maximized. The applied RF field wasfound from the precession frequency to be about 8 G.
Figure 5 shows the resonance curves obtained at 300
K and 100 K . Dashed lines show the reference resonance curves obtained from the same measurement
but on carbon powder. These references show a zeroshift. The shift of the resonance frequency was 2 and6 G at 300 and 100 K, respectively. The shift is corresponding to the paramagnetic shift caused by thehyperfine field at the muon site. This tendency of thetemperature dependence of the hyperfine field at themuon site is consistent with that of the Co-spin susceptibility obtained by a 59CO-NMR measurement. 4 )Therefore, this fact shows that the obtained hyperfine
field at the muon site is originated from the spin susceptibility of the Co-spin. These results indicate that
we can study, under the decoupled longitudinal field,
the hyperfine interactions between the muon spin andthe magnetic moments by using this RF-p,SR systemwith the experimental tolerance of 0.1%.

LaCo0 30.15 kW RF power at 40.000 MH z
12

O...bo'T=300K10

t.= 9 G
shift ~2G

8

T=IOOK7

t.= 18 G
shift ~6G

... +

2940

c.rt>o.

2960

j ( L.CcO,

I(L'COO'

2980

3000

)020

3040

Fie ld (G)Fig. 5. Resonance curves at 300 K and 100 K. The dashedlines show the resonance curves of carbon powder as areference of zero-shift resonances. .6. is a halfwidth of
the resonance curve.

o

5

to

t

15

20

(Ilsec)Fig. 4. RF-JLSR time spectra obtained at 300 K. The
spectrum at the bottom shows the muon spin rotation
around the RF field under a just-resonance condition.
The other two spectra show the muon spin rotation under off-resonance conditions.

References
1) K. Nishiyama: in Perspective of Muon Science (NorthHolland, Amsterdam 1992), p. 199.
2) Y. Kitaoka et al.: Hyperfine Interactions 12, 51 (1982).
3) 1. Watanabe et al.: RIKEN Accel. Prog. Rep. 31, 111(1998) .
4) M. Itoh et al.: J. Phys. Soc. Jpn. 64, 970 (1995).

1173. Radiochemistry and Nuclear Chemistry

RIKEN Accel. Prog. Rep. 31 (1998)

The Jump Mechanism of Self-Interstitials in Pure Iron
Y. Yoshida, Y. Kobayashi, F. Ambe, E. Yagi, R. Sielemann,*1
A. Feinauer,*2 and A. Seeger
The jump mechanism of self-interstitials is still not
well understood in pure Fe and appears to be one of themost important problems in the field of point defects
in metals. However, no direct observation of the jumpprocesses of the self-interstitials in pure Fe has beenachieved yet. The in-beam Mossbauer spectroscopyusing the 56Fe( d,p )57 Fe reaction by a deuteron beamfrom the RIKEN AVF-Cyclotron is now opening a possibility to study the elementary jump process of selfinterstitials in a pure single crystal iron. I) The excited probes of 57Fe were produced in a natural-Fe
single crystal by the 56Fe( d,p )5 7Fe reaction, followedby its ejection from the normal lattice sites due tothe highly energetic deuteron, which may produce theself-interstitials of Fe. In order to determine the jump
vectors of the interstitial 57Fe atoms, the angular dependence of Mossbauer spectrum was measured at different crystal orientations.
There was, however, a difficult problem due tothe thickness ( 1 mm) of the sample used in theexperiments I) till recently, which caused an additional
complexity to the experimental results. The problem
was an accumulation of the deuterons stopped about
100 p,m of depth, close to the surface, which gave astrong effect on the spectrum, so that it was rather
difficult to extract information on the jump processesof the self-interstitials from the spectra. In the present
investigation, however, we have succeeded to make athinner sample as thin as 100 p,m, which made us
possible to measure Mossbauer spectra without any
deuteron accumulation.
The angular dependent Mossbauer spectra at 400
and 150 K are shown in Figs. 1 and 2, respectively,
which correspond to the temperatures above and below the stage I, which is a recovery stage of the selfinterstitials in pure iron. This means that the selfinterstitials will start migrating within a time scale ofthe practical measuring time, i.e., 100 ns in the 57Fe
Mossbauer spectroscopy. The spectra of Figs. 1 and 2
were fitted using two six-lines: one component with alarger magnetic splitting corresponds to the substitutional Fe, and the other with a smaller magnetic splitting to Fe atoms on a defect site. It may be possible
now to compare the area intensities of defect components as a function of the angle with those predictedfrom different jump models. 2) The result will be published elsewhere.

400 K

200

t <~

1

00>'

150
100

Z

150

.

32°'.

. .
.
.... .:.......:',..,.
•~gg.:,:~.:'

f

<110>

·10

·8

I

~..

.:~"':'.

::t~
45°

-6

·2

-4

.

0

2

8

1
10

Velocity (mm/s)

Fig. 1. The angular dependence of the Mbssbauer spectra
at 400 K for the detection direction between (100) and(110).
150 K::t~l
i::t~1

! =t

,'

150
100
-10

1

450'

A tt

< 110>

L

A

/!,.

,v.A

~~~/V;~
I

,

,

,

,

,

-8

-6

-4

-2

0

2

,

,

J

8

10

Velocity (mmls)

Fig. 2. The angular dependence of the Mbssbauer spectra
at 150 K for the same detection as Fig. 1.

References*1*2

Hahn-Meitner Institute Berlin, Germany
Max-Planck-Institute Stuttgart, Germany1) Y. Yoshida et al.: RIKEN Accel. Prog. Rep. 29, 111(1996); RIKEN Accel. Prog. Rep. 30, 103 (1997).
2) A. Feinauer et al.: HMI-Berlin Ann. Rep. B 540, 11(1995).

119

RIKEN Accel. Prog. Rep. 31 (1998)

Dynamic Behavior of 57Fe Atoms in Solid Ar and Solid Xe
Y. Yoshida, Y. Kobayashi, K. Hayakawa,* K. Yukihira,*
S. Nasu, and F. Ambe
After Coulomb-excitation and recoil-implantation of
57Fe into solid Ar and solid Xe, we observed 1 ) the
Mossbauer spectrum consisting of two broad singlelines at 5 K, which further showed a motional averaging at 20 K in the solid Ar and at 50 K in the solid
Xe, respectively. This suggests that the Fe atoms start
jumping already at 5 K between different lattice sites inthe solid-state face-centered-cubic (FCC) inert gases.
During the course of the experiments, however, it wasnoticed that the magnitude of the line broadenings ofboth components changed considerably from one specimen to another, even if the spectra were measured at
the same temperature by implanting the same number of 57Fe atoms into the inert-gas solids. In orderto solve this problem, we have performed a systematic
data taking as functions of the temperature, the Fedose , and the thickness of specimen.
The thickness of the samples was varied roughly between 0.2 and 1 mm by changing the total amount of
the Ar-gas condensed on a copper substrate. After thecondensation at 70 K , the specimen was cooled down tothe experimental temperatures between 5 and 30 K following the coexisting curve of the Ar solid-gas phases.
The cooling rate was 1 K/min. Finally, we obtained atransparent crystal with a typical mosaic size of 5 mm.
The Ar beam intensity was 15pnA, which allowed us
to evaluate a Mossbauer spectrum every three hours
to follow a development of the spectral shape. The
total number of 57Fe atoms implanted into the solid
Ar was estimated to be 1 x 10 10 /cm 2 after a typicalmeasurement time for 8.6 x 104s.
Figure 1 shows the 57Fe Mossbauer spectra in thesolid Ar at different temperatures for the specimens
with different thicknesses; each column, from the left tothe right, corresponds to the estimated thickness of 0.2,
0.8 , and 1 mm, respectively. It is clearly seen that theline width of the singlet at the left-hand side increases
not only with increasing temperature, but also withincreasing the thickness of specimen. In addition, thespectra became broader with increasing the measuringtime, which are not shown in this report though.
In the former works 2 ) on 57Co/ 57 Fe into solid Ar ,a 3d 7 state and a 3d 6 4s 1 state were observed, but
in the present experiment , both components are notseen in these spectra. The isomer shift for the component at the right hand side in Fig. 1 is very close
to that of the "FeD monomer state (configuration
3d 6 4s 2 ) " , which was reported in an experiment after

Shizuoka Institute of Science and Technology

120'.- I~,. A/. .:: ~ I ~ I::I~tldo < Specimen Thickness < thick,-----------,~ r-----------,

sx

"

"

• •,

sx

I

.,'

:.

.x

~,~ ~
,
-

••••

"--••

#

.

11X

::~

100
ISO

~

I

I~

L._-6
-;---""~.l'---;;O-;-l~4--:-', L-6.,..-..:---:.l,....-:-O--:-1~4-,7-'

Velocity (mm/s)

-6

..

.1

0

1

4

,

Fig. 1. 57Fe Mossbauer spectra in the solid Ar at different temperatures for the specimens with different
thicknesses: Each column, from the left to the right,
corresponds to the thickness of 0.2, 0.8, and 1 mm, respectively.

the coevaporation2 ) of 57Fe together with Xe gas. Accordingly, this component may be assigned to the Feostate. On the other hand, the broader component at
the left-hand side appears to be the first observationin the inert-gas solids, and may correspond to either
the Feo state on a different lattice site, or a different
ionic state such as Fe 2 + or Fe 3 +.
In the present experiments, the implantation depth
and the dose of 57Fe atoms and even the quality of
the crystals are supposed to be quite identical for
all the spectra corresponding to the different thickness. Therefore, the observed line broadenings can not
be attributed to the defects produced during the Fe
slowing-down process, but rather to a charge-up effectintroduced by the highly ionic 57Fe. The accumulated
charges may cause an electric field to the 57Fe ions,leading to an enhancement of the atomic jumps. In
order to understand the fast dynamic behavior of the
Fe atoms in the solid Ar, however, both the charge
distributions induced by the 57Fe ions and its relaxation process must be further quantitatively investigated. The details will be published elsewhere.
References
1) Y. Yoshida, Y. Kobayashi et al.: RIKEN Rev. No. 16,
p. 19 (1997) .
2) M. Van der Hyden et al.: Phys. Rev. B 36, 38 (1987).

RIKEN Accel. Prog. Rep. 31 (1998)

57Fe Mossbauer Studies Using 57Mn Nuclei
Implanted into Al and Si
Y. Kobayashi, Y. Yoshida, K. Hayakawa,* K. Yukihira,* A. Yoshida,
Y. Watanabe, N. Aoi, S. Nasu, and F. Ambe
Energetic radioisotope beams (RI-beams) which areproduced as secondary beams have become very attractive in the fields of materials science. Since theimplantation energy into materials can be in the order of GeV, the beams would enable to modify the
microstructures and to synthesize novel species in materials on a scale of several hundred p,m in depth. We
can make use the most of RI-beams not only as nuclear probes to obtain atomic information of the materials immediately after implantation, but also as tools
to change the physical and chemical properties of materials. We report here the results obtained from thein-beam Mossbauer studies on 57Fe/ 57 Mn in Al and Si.
Energetic 57Mn nuclei (T 1/2 = 1.45 min) were produced by the projectile fragmentation process of an 80
A MeV 59 Co beam. The 59 Co beam reacted against
a production target of 185 mg/cm 2 Be. The reaction
fragments were collected and analyzed by in-flight isotope separation using the RIPS (RIKEN Projectilefragment Separator). To stop the 57Mn nuclei in thespecimen for implantation, we suppressed the beamenergy using a degrader of a 500-J.Lm-thick Al plate.
The implantation intensity of 57Mn atoms were estimated to be typically 2 x 105 particles/so We used two
specimens: an Al foil and a single crystal of Si wafer
with thickness of 135 mg/cm 2 and 117 mg/cm 2 , respectively. The experimental set-up and details were
described in Ref. 1.
The Mossbauer spectrum of 57Fe having decayedfrom 57Mn in the Al foil was measured at 30 K, as
shown in Pig. 1. A single component was observed in
the Mossbauer spectrum, and this broad line was fitted with the isomer shift, 1.S. = -0.53 (5) mm/s andr = 0.64 (8) mm/s. The obtained value for 1.S. coincides with that for substitutional 57Fe atoms in Al
observed in the in-beam experiment after the Coulomb
excitation and recoil-implantation. 2 ) However, no lines

120r---------------------------~:: I·····,}~;....~··.. .' I
_ : ···...... . ;··A :.'...
.......
·i··::~~···,

-3

-2

-I

0

i·_

2

120

110

I

100

....'..

..

24 K

-1

o

2

I

..",.,~..,-: .:.- .
, .. )~ . .•... ;.......

",

-3

-2

3

Velocity [mm/s]

Fig. 2. Mossbauer spectra of 57Fej 57Mn in Si at 24 K.
(The total measuring time was 12 h.)corresponding to 57Fe in interstitial sites, as observed
remarkably at the low temperature less than 30 K in
the Coulomb excitation experiment, were observed in
the present experiment.
The implantation of 57Mn beam into the Si wafer
was performed at 24 K. The spectra consists of two
component, as shown in Fig. 2. In the case when it
was analyzed with two Lorentzian curves, it was fittedwith a relatively sharp line at around -1 mm/ s and avery broadened line at around 0.1 mm/s, respectively.
The line at lower velocity appears to correspond to
the interstitial 57Fe in Si, which was observed in thein-beam experiment after the Coulomb excitation andrecoil-implantation. 3)
It is quite interesting that there are differences in
the results between the projectile fragmentation reaction and Coulomb excitation/recoil-implantation experiments. This is considered due to the entirely different range of time involved for measurement after
the implantation in both experiments: 57Mn possesses
a much longer half-life of 1.45 min in contrast to 57Pe
half-life in the excited level (T1 / 2 = 98 ns). Alternatively, the observed difference is ascribed to the final
chemical state of implanted 57Mn nuclei different fromthat of 57Fe nuclei.
In conclusion, we have successfully observed, for the
first time, Mossbauer spectra of the 57Pe/57Mn nuclei implanted into specimens as an energetic RI-beam.
Implantation of the projectile fragments separated byusing the RIPS can open a new possibility to use as
many kinds of short-lived nuclear probes for solid-sateand materials science.

3

Velocity [mm/s]

Fig. 1. Mossbauer spectra of 57Fej57Mn in Al at 30 K.
(The total measuring time was 10 h.)

References
1) Y. Kobayashi et al.: Hyperfine Interact., in press.
2) M. Menningen et al.: Europhys. Lett. 3, 927 (1987).
3) P. Schwalbach et al.: Phys. Rev. Lett. 64, 1274 (1990).

Shizuoka Institute of Science and Technology

121

RIKEN Accel. Prog. Rep. 31 (1998)

Coulomb Excitation in In-beam Mossbauer Spectroscopy
Y. Hsia,* Y. Kobayashi, and F. Ambe
The differential excitation cross-section for the electric excitation EA of nuclei is 1 )daE>' =

Z1e)2 2>. 2( hV a- + B(E)")d!E>.(B , f,)

Ii

If

Iff

process I: 112- l~V 5/2- l~V 312process II: 112- 3~V 312- 3meV 3/2-

(1)

where

4rr2

dIE>. = (2)" + 1)3. -4 (B)
L:/.L 1Y>'/.L (rr)
2 , 0 12 Il>./.L(B, f,) 12 sm
2" dD
(2)

(=

Here, V is the velocity of the projectile, a~:f,r~2)
the half distance of closest approach in a head-on collision, Zl and Z2 the charge numbers of the projectileu)and target nuclei, and mo ( = A~~t12
their reduced
mass. B(EA, Ii -t If) is the reduced transition probability associated with the multipole order EA. The orbital integrals 1>./1- ((},~) for E2 Coulomb excitation has
been calculated by numerical methods as a functionof the scattering angle () in the center-of-mass systemwith a parameter ~ (=The motion of projectile in the Coulomb field of
nucleus is characterized by Sommerfeld parameter 1}:1} = ZlZ2e2/TiV which is the effective strength of theinteraction.
The M6ssbauer state of 57Fe is excited via E2transitions to the 5- /2 and 3- /2 states at 136 and366 keY. About 90% of their population decays into
the M6ssbauer state at 14.4 keY. The 57Fe Coulomb
excitation processes in in-beam M6ssbauer study aremainly E2 processes (see Fig. 1). The M6ssbauer
state 14.4 keY is hardly excited directly due to its
small B(E2) value (9.7e 2 fm 4). The collision parameters were evaluated under the experimental conditionsof the AVF Cyclotron at RIKEN. 2 ) The related parameters are: (1) the initial projectile velocity Vi =at:).

/'f!; = 0.073c and the final relative velocity Vf =. !2(E-6.E) = 0.073c. Here tlE' = (1 + &) tlE is
V
A2
mI

'

the excitation energy. For the process I, tlE~ = 231
keY, and tlE~I = 622.8 keY for the process II. (2)the relative excitation energy parameter ( is definedby: ( = 6.:'. Therefore, (I = 3.97 X 10- 3 « 1,
(II = 1.07 X 10- 2 «1. (3) Sommerfeld parameters.
Both initial value 1}i and final value 1}/ are close to
46.8 . They are much larger than 1. This implies thatthe process can be described semi classically. (4) Symmetrized parameter of orbital. Generally, the orbit is
not a perfect hyperbola, because the projectile loses its
energy during the excitation process. However, in ourcase, Vi : : : : Vf and a = !~t~~~ = 5.73 fm. Therefore,
we have a symmetrical orbital. (5) A parameter ~ forexcitation cross-section function, f E)" (~), defined by
On leave from Department of Physics, Nanjing University,
Nanjing, China as an Eminent Scientist of RIKEN.

122

Fig. 1. The main 57Fe excitation process in the 57Fe
in-beam Mossbauer study.
f, -a6.E _ Z1 Z2e2 6.E
liV-~2E 'For 57Fe Coulomb excitation, 6 = 0.055 and 6 I =0.147.
As mentioned above, the excitation cross-section
function can be calculated by the semiclassical approximation. According to fE2(1}i = oo,~) tabulation in
Ref. 3, fk2 = 0.88 and fk~ = 0.80 for 6 = 0.055 and~II = 0.147. Using the experimental value of B(E,A) ,Bk2 = 410e 2 fm 4 and Bk~ = 320e 2 fm4, we obtain the
excitation cross-section from Eq. (1) as ak2 = 822 mb
and ai/2 = 583 mb.
The ,-emission from the Coulomb excited nucleus is
not isotropic. The differential excitation cross-section
for E2 excitation can be calculated according to Eqs.
(1) and (2) with A = 2 and () = (}c which is the scattering angle in the center-of-mass system.
Pure Coulomb excitation is only realized under thecondition that the kinetic energy of the heavy-ion projectile is lower than the Coulomb barrier. Coulomb
barrier is given by EB = Z1 Z2e2 / R with the effective
radius R of interaction
R = TO (A~ / 3 + A~ /3) ,where ro = 1.5 fm. The experimental condition at
RIKEN is EB = 61.8 MeV. On the other hand, the kinetic energy E of the projectile should be high enough,otherwise the collision becomes adiabatic and the excitation cross-section becomes small. From Ref. 2, thelower limitation should be written asA) 1/3
E > 0.2Z1 ( Z~
(Z26.E)2 /3
where both tlE and E are in the unit of MeV. Therefore, the best bombarding energy of the projectile under the experimental condition at RIKEN should be in
the region of 21.0 MeV < E < 61.8 MeV.
References
1) K. Alder et al. : Rev. Mod. Phys. 28, 422 (1956).
2) Y. Yoshida and Y. Kobayashi et al.: RIKEN Accel.
Prog. Rep. 28, 102 (1995) .
3) K. Alder and A. Winther: CERN Report T /KA-AW-l,
1954.

RIKEN Accel. Prog. Rep. 31 (1998)

Multitracer Study on the Permeation of Rare Earth Elements
through a Supported Liquid Membrane
S. Ambe, T. Ozaki, S. Enomoto, and F. Ambe
Separation by means of supported liquid membranes
is a useful method for the preparation and preconcentration of radioactive nuclides. The permeation of rareearth elements through a bis(2-ethylhexyl) hydrogen
phosphate-decalin membrane supported on a microporous polytetrafluoroethylene sheet was studied using
a multitracer containing the radioactive nuclides of Sc,
Zr, Nb, Hf, ee, Pm, Gd, Yb, and Lu.
Disks of Au were irradiated by a 135 MeV/nucleon
12C, 14N, or 16 0 beam accelerated by the RIKEN Ring
Cyclotron. The Au was removed from a multitracer
by chemical separation procedures. The multitracer in
the aqueous solution was separated into three groups
by a cation exchange resin. The rare earth element
group which also contained Zr, Nb, and Hf was stored
in 3 mol dm- 3 HeI. One hundred p'! of the group
tracer solution was added to the feed solutions, and theacidity of the solutions was adjusted to be 0.4, 0.3, 0.2
mol dm -3 Hel, pH 1.4, 2.4, and 3.4. As for receiving
solutions, 0.5, 0.75, 1.1, 2.3, and 4.0 mol dm- 3 Hel
solutions were used.
The permeation of rare earth elements from the feedsolutions of 0.4, 0.3, 0.2 mol dm- 3 HCI, pH 1.4, 2.4,
and 3.4 into the 0.5 mol dm- 3 HCI receiving solution
was carried out. Among the various feed solutions,the solution at pH 1.4 gave the highest permeation
rate for Ce, Pm, and Gd, amounting to about 95% ofpermeation for Ce and Pm, 80% for Gd, and 10% for
Yb in 21 h. Scandium, Zr, Nb, Hf, and Lu were nottransported at all from the feed solution.
The permeation of rare earth elements from the feedsolution at pH 1.4 into the 0.75, 1.1, 2.3, and 4.0
mol dm- 3 HCI solutions was carried out. Figure 1
shows the transport rate of the rare earth elementsfrom the feed solution at pH 1.4 into the 4.0 mol dm- 3
HCI receiving solution. The percentage of permeationof the elements from the receiving solutions of different Hel concentration at 21 h is shown in Fig. 2. An
increase in the Hel concentration of the receiving solutions enhanced the permeation of Gd, Yb, and Lu
markedly.
The enhanced permeation of Gd, Yb, and Lu into
the 4.0 mol dm- 3 HCI receiving solution indicates thatthe back-extraction is a rate-determining step in the

4.0 M
100

-----

l 75
"!

.......•......

Do

Pm......... Gd

.•..

0

•c:
!!

Ce

. __

50

-

~

25

_.

--.- --

Vb
Lu

0

0

6

10

16

20

25

llme (h)Fig. 1. The transport rates of lanthanide ions from thefeed solution at pH 1.4 to the 4.0 mol dm- 3 Hel receiving solution through a membrane with bis{2-ethylhexyl)hydrogen phosphate-decalin in the ratio of 1.

100

!

.....

~

•8.c

. ..• ...

Gd'---.-00. Yb

50~---.---

Lu.... / __ 4

• __ .-•• -._.-.-:-:_':~-~ •• _. - 11

0
0

1

2

3

4

5

Concentration of Hel (M)Fig. 2. Percentage transport of lanthanide ions from thefeed solution at pH 1.4 to the 0.75, 1.1, 2.3, and 4.0
mol dm -3 Hel receiving solutions through a membranewith bis{2-ethylhexyl) hydrogen phosphate-decalin in
the ratio of 1 after 21 h-permeation.

permeation of heavy rare earth elements, because they
form stable complexes with bis(2-ethylhexyl) hydrogen
phosphate in the membrane. Scandium, Zr, Nb, and
Hf were not detected even in the 4.0 mol dm- 3 Hel
receiving solution.

123

RIKEN Accel. Prog. Rep. 31 (1998)

Model Study of Acid Rain Effect on Adsorption ofTrace Elements on Soils (III)H. Wang, S. Ambe, N. Takematsu, and F. Ambe
Acid rain has bad effects not only on vegetation but
also on soils. It changes the adsorption or retention ofmany elements in the soil-pore water system, which inturn exerts a significant influence on the availability ofnutrient elements for plants.
In our previous papers, adsorption of many trace elements on kaolin, forest soil, and Kureha Soil from amodel acid rain (pH 1.8-5.6) has been studied using
the multitracer technique. 1 ,2) In this report, black soil
(original and without organic matter) was used as anadsorbent to investigate the effect of organic matter on
the adsorption of trace elements, because soil is principally composed of aluminosilicates (clay minerals),organic matter (humic substances), and Fe-Mn oxides.
The black soil is from the Mt. Nasu system(Fukushima prefecture) and its content of organic carbon is 12.5% (about 25% as organic matter). The organic matter was removed by heating with 30% H 2 0 2
at 80 °C for 2 hours. Three hundred (300) mg of soil
was suspended in 10 ml of the model acid rain containing the multitracer (Be, Sc, Mn, Fe, Co, Zn, As, Se,
Rb, Sr, Y , Zr, Tc, Ru, Rh and Re). The suspension
pH value was adjusted to a desired value (1.8- 5.6) with
HCl or NaOH solution. After equilibrium (shaking forseveral days) , the suspension was centrifuged. The pH
value and the ')'-ray spectrum of the supernatant were
measured. The adsorption percentage of each element
was calculated by comparing the ')'-ray intensities at agiven energy before and after adsorption.
In general, the pH dependent adsorption of elementson the black soil (Fig. 1) is similar to that on all thesoils examined so far , although absolute adsorption
percentages are varied. The adsorption of cationic elements increases with the increase of pH, whereas thatof anionic elements (As, Se, Tc and Re) is vice versa.
The adsorption of Sc, Fe and Zr is higher than that ofother cationic elements. These trends can be explainedby the complex formation between surface functionalgroups and cations or anions.
The adsorption of Zr , Ru, Rh, As, and Se on theblack soil is not appreciably affected by the removal oforganic matter, although that of Zr, As, and Se is toohigh to discriminate between the soils with and without organic matter. On the other hand, the removal oforganic matter causes a distinct adsorption decreaseof Be, Sc, Mn, Fe, Co, Zn, Rb, Sr, Y, Tc, and Re,
especially of Tc and Re.
The organic matter in soil (humic substances) havehigh contents of carboxyl and phenolic hydroxyl groups

124

\!
c

.52

Q.

~
"0
«

"'[ ] D 0
75

Be °

50

0 x

:!5

x

Mn

0

0

Sc

0

x

o 00 X

xx

X

0

~Q
Q.

100

«

0

x

Rb

0

o
o

x

o

50

~
"0

Zn

0

75

x

o

o

Sr
o

x

x x

0

25

o

~x

x

ox

o x

o
1 1~ D 0 []::.
xx 0 ex
OX

~

As

Zr

Ru

Se

,p ex

°1234 5 6 1 2 3 4 5 6 1 2 3 4 56

pH

pH

pH

DR'
..
1 23 4 56

pHoblack soilx

black soil without organic matter

Fig. 1. The pH effect of model acid rain on the traceelement adsorption on black soil and on soil without
organic matter.
as ligands, with which a broad range of elements canmake complexes. This is the main reason why the adsorption of many elements decreases after removal oforganic matter.
In brief, the experimental results of this study predict that acid rain will reduce the retention of cationic
elements in soil and that it will enhance the retentionof anionic elements. The contents of organic matterand oxides in soil affect the extent of adsorption, andtheir pH dependence of adsorption is similar to that ofaluminosilicates.
References
1) H. Wang et al.: RlKEN Accel. Prog. Rep. 30, 122(1997).
2) H. Wang et al.:(1997).

RIKEN Accel. Prog. Rep. 30, 123

RIKEN Accel. Prog. Rep. 31 (1998)

Simultaneous Determination of Stability Constants of Humate
Complexes with Various Metal Ions Using Multitracer Technique t
Y. Takahashi, Y. Minai, S. Ambe, Y. Makide,·1 F. Ambe, and T. Tominaga*2
Complexation with humic acid, naturally occurringorganic polyacid, has been recognized as an important factor controlling the behavior of various elementsin the natural aquifer. I ) The stability constant of humate complex is an important and fundamental datum to evaluate the humate formation on the speciation of each element. In the present study, the multitracer technique was applied to obtaining the stability constants of humates of 19 elements (Be, Ca,
Sc, V, Cr, Mn, Fe, Co, Zn, Ga, Sr, Y, Ba, Ce, Eu,
Gd, Tm, Vb, and Lu). The stability constant ((3)
was determined by a solvent extraction method using di(2-ethylhexyl)phosphoric acid (DEHP) as theextractant. 2 )The log.B determined are plotted against degree ofionization of humic acid (Q) and against pH in Fig. 1.
As a whole, the stabilities of humate complexes apparently increase with the increase in either pH or Q.
Similarly, the apparent pKa of humic acid obtained by
pH titration increases with either pH or Q. The stability constants of humates for trivalent ions are generally
larger than those for divalent ions. For alkaline earth
metal ions, the stability constants of humate complexes
were in the order of Be-humate> Ca-humate > Sr-,
Ba- humate. This shows that the humate of alkaline
earth metal ion with smaller ionic radius is more stable,
which suggests that the humic acid is a "hard" ligand.
The increase of log.B and pKa with the increase in pH
or Q can be explained by the increase of electrostatic
potential of humic acid regarded as polyelectrolyte. 3 )The slopes of log{3 for divalent ions measured against
either pH or Q were smaller than those for trivalentions, while they were larger than those for V0 2 + andproton (= pKa).
A simple electrostatic model based on the coulombic
interaction between a metal ion and a polyelectrolyte
was employed to explain the dependence of humate stability constants of various elements on pH and Q.3) The
intrinsic stability constant, (3int, defined in the model
represents the stability of the humate complex with an
ion when the electrostatic effect of humic acid is negligible. The deviation of apparent stability constantfrom the intrinsic one with increasing Q or pH reflects
the increased electric field in the vicinity of the polyelectrolyte. The relationship between log{3 and log{3intis expressed as: 3 )log {3 = log (3int + k Zi Q,(1)where k is a constant and Zi is the charge of the metal
ion. The second term in the right hand side of Eq. (1)*1*2Condensed from the article in Sci. Total Environ. 198, 61(1997).
Radioisotope Center, University of Tokyo
Department of Chemistry, School of Science, University of
Tokyo

If

••

4

17

(a)

0.3

0.4
0.5
0.6
Degree of ionization (a)

0.7

(b)

0 .3

0.4
0.5
0 .6
Degree of ionization (a)0.7

Fig. 1. The Q (degree of ionization of humic acid) and pH
dependences of pKa of humic acid and stability constants of humate complexes «(3) with (a) V0 2 +, anddivalent ions of Be, Ca, Mn, Co, Zn, Sr, and Ba, and(b) trivalent ions of Sc, Cr, Fe, Y, Ce, Eu, Cd, Tm, Yb,
and Lu at C s = 0.020 M.

is introduced to take account of the electrostatic interaction between humic acid molecule and the metal ion
which increases with gradient of the log{3 vs. Q. Basedon the linear relationship observed between log{3 and Q(Fig. 1), log.Bint was obtainable for various metal ionsby extrapolation to Q = O. The log.Bint was plottedagainst the stability constants of the corresponding oxalate complexes (metal ion: oxalate molecule = 1:1).
It was found that each log{3int value is identical to thestability constant of the corresponding oxalate. Thissuggests that a bidentate carboxylate site may act as
the complexing site in the humate formation with traceelements.
Based on the stability constants obtained here andthe humic acid concentration in natural water, the ratio of humate complex species to free metal ion in thenatural environment was estimated; similar estimation
was also conducted for carbonate and hydroxide complexes for each element. As the result, it was foundthat humates may be the dominant species for Be,
Cr(III), Fe(III), and rare earth elements (REEs). In
particular, the humate formation appears to be substantially important for REEs, in accordance with ourprevious study on the adsorption behavior of the traceelements including REEs.4)
References
1) W. Stumm and J. J. Morgan: Aquatic Chemistry (Wiley, New York, 1995).
2) R. A. Torres et al.: Radiochim. Acta 35, 143 (1984).
3) E. Wilson and P. Kinney: Wat. Res. 22, 281 (1977).
4) Y. Takahashi et al.: J. Radioanal. Nucl. Chern. 205,
269 (1996).

125

RIKEN Accel. Prog. Rep. 31 (1998)

Comparative Subcellular Distribution of Radioactive Mn, Fe, Zn,
and Se Tracers in Brain and Liver: Why, in Brain, Do most of
Their Proteins Exist in Mitochondrial and Nuclear Fraction?
R. Amano, S. Oishi, M. Ishie,* M. Kimura,* S. Enomoto, and F. Ambe
As expected by the low required concentrations, themicro essential elements, Mn, Fe, Zn and Se, serve primarily catalytic functions in cells and organisms. I) Iron
deficiency causes anemia, providing clear evidence ofFe essentiality. It is also a component of numerous
proteins that exert critical roles in energy metabolism,
notably the cytochromes and the enzymes in the electron transport system. Manganese deficiency results
in a distinct pathology, including reproductive failure, skeletal defects, and ataxia; the Mn ion is also
a component of several enzymes, including mitochondrial superoxide dismutase, pyruvate carboxylase, andarginase, although these enzymes may not be related
directly to the observed pathology of Mn deficiency.
A similar situation exists in the case of Zn, whose
deficiency pathology includes stunted growth, skin lesions, and reproductive difficulties. Zn is a componentof enzymes that catalyzes more than 50 different biochemical reactions as well as a component of proteins
involved in gene expression. However, none of these
proteins or enzymes has been identified with specific
Zn deficiency pathology. Besides its catalytic role insome enzymes, Zn exerts a structural role in proteins,particularly in the Zn finger proteins involved in genetranscription. Se deficiency result in severe pathology,
including cardiomyopathy and skeletal muscle defects.
Se is a component of some proteins, the glutathione
peroxidases and the iodothyronine-5' -deiodinases.
Using a multitracer solution prepared by RIKEN
Ring Cyclotron, we have studied the subcellular distribution of several trace elements in the liver and kidney,and obtained the preliminary results to speculate theirbiochemical or physiological functions. 2 ,3) The present
work aimed to examine the subcellular distribution of
54Mn, 59Fe, 65Zn and 75S e in the brain of normal mice,and to compare the brain distributions with the liver
ones. A multitracer solution was prepared from fourcommercially available tracers. Four male C57BL/6N
mice weighing 19-20 g (6 weeks old) were used. Physiological saline solutions (O.OOlN HCI, pH 2- 3) containing the radioactive multitracer were intraperitoneallyinjected (0.2 ml/mouse). At 48 hr after injection, themice were sacrificed under ether anesthesia, and theblood was collected. After this, the brain was excised. The excised brain was homogenized in a cold
(5°C) 0.25 M sucrose solution containing 0.01 M TrisHCI buffer at pH 7.6 (10% weight per volume). Subcellular fractionation was carried out at 4 °C accordSchool of Health Sciences, Faculty of Medicine, Kanazawa
University

126

ing to a modification of the method of Hogeboom andSchneider. 4) Subcellular distributions are expressed as
fractionation percentages (the radioactivity percentage
of nuclear, mitochondrial, microsomal or supernatantfraction in %).
Figure 1 shows the subcellular distribution of radioactive Mn, Fe, Zn and Se tracers in the brain of
C57BL/6N mice at 48 hr after injection together withthat of the liver of ddY mice reported in the previous
paper. 2 ,3) Surprisingly, the mitochondrial and nuclear
fraction percentages of the brain were found definitely
higher than those of the liver. This fact is surely due
to the difference of soft tissue, not to the differenceof mouse strain. We plan to examine the subcellular
distributions in several soft tissues including brain ofsame mouse strain.
(A) Brain(B) Liver

Fig. 1. Subcellular distributions of radioactive Mn, Fe, Zn
and Se tracers in the brain(A) and liver(B) of mice at
48 hrs after injection.

Undoubtedly, the radioactive Mn, Fe, Zn and Se
tracers in all fraction become a component of numerous proteins at 48 hr after i.p. injection. In the brain,large parts of these metal proteins probably exist in
mitochondrial and nuclear fraction. In future, we will
confirm and discuss these phenomena.
References
1) B. L. O'Dell and R. A. Sunde: in Handbook of Nutrition-

ally Essential Mineral Elements, edited by B. L. O'Delland R. A. Sunde (Marcel Dekker, New York, 1997), p.
4.

2) R. Amano, S. Oishi, S. Enomoto, and F. Ambe: RIKEN
Rev. No. 13, p. 31 (1996).
3) R. Amano, S. Oishi, S. Enomoto, and F. Ambe: Ann.
Clio Lab. Sci. 26, 531 (1996).
4) G. H. Hogeboom: in Methods in Enzymology Vol. 1,
edited by S. P. Colowick and N. O. Koplan Vol. 1 (Academic Press, New York, 1955), p. 16.

RIKEN Accel. Prog. Rep. 31 (1998)

Comparative Distribution of the Trace Elements Sc, Mn,
Fe, Co, Zn, Se, Rb, and Zr in the Brain andOther Organs of C57BL/6N MiceS. Oishi, R. Amano , M. Nishida,* T. Yonebayashi,* A. Ando,* S. Enomoto, and F. Ambe
Multitracer enables simultaneous tracing of various
elements in the identical system, and makes a strict
and accurate comparison of their behavior, minimizing the undesirable effects of both peculiarities of samples and variation in experimental conditions.1- 5 ) In
the present work, we have applied it to the study ofbiobehavior of Sc, Mn, Fe, Co, Zn, Se, Rb and Zr
trace elements in normal C57BL/6N mice. The tissue
distribution of the 8 elements was examined among 11organs (brain, cardiac muscle, lung, liver, spleen, pancreas, kidney, bone, thighbone muscle, eyeballs andtestes) and blood, and evaluated in terms of "tissue
uptake rate (the percentage of injected dose per gramof tissue: %dose/g)".
Male C57BL/6N mice were purchased from Charles
River Japan Inc. , and fed with a standard laboratory
diet and had a free access of drinking water in steel
cages during 1 week prior to administration. A nocarrier-added radioactive multi tracer solution was obtained from the Ag (purity:more than 99.99%) target
irradiated by 135 MeV/nucleon N-14 beam accelerated by RIKEN Ring Cyclotron. Preparation for of
the multitracer solution from Ag target was carriedout in the Radioisotope Center, Kanazawa University.
After evaporation of the no-carrier-added multitracer
solution containing hydrochloric acid, a physiologicalsaline solution was added to obtain the radioactive
multitracer solution for injection. The 8 elements (Sc ,Mn, Fe, Co , Zn, Se, Rb and Zr) were evaluated inthis experiments. At 6, 12, 24 and 48 hr after intraperitoneal injection (0.2 ml) into 20 mice, the mice
were sacrificed under ether anesthesia, and about 0.2
ml of blood was collected, and then the above 11 organs
were excised. These tissues were weighed immediately
and freeze-dried. The dried samples were subjectedto the gamma-ray spectrometry with pure Ge detectors against an appropriate standard sample in orderto obtain the tissue uptake rate. (See, Table 1.)
All the 8 radioactive tracers were observed in the
cardiac muscle, lung, liver, spleen, pancreas and kidneys. However, in the brain, muscle and testes , theuptake rates of Fe were found negligibly low. On theother hand, in the kidneys, liver, pancreas and spleen,
the uptake of Fe was significantly high. This biobehavior of the trace Fe permits us to assume the following
consideration. Iron is essential and exists in all organs
including brain, muscle, testes, liver, kidneys, pancreasand spleen. Our results lead to the estimation that thetransportation rates of Fe tracer to brain, muscle andtestes are considerably slower than those to kidneys,
liver, pancreas and spleen. The transport mechanismof Fe for the former group is presumably different from
School of Health Sciences , Faculty of Medicine, Kanazawa
University

Table 1. Tissue uptake rates of the brain at 6, 12, 24, and48 h after injection of a multitracer solution.
Brain. 6 Sc
5<

Mn

5· CO
59 Fe
65 Zn
75 Se
83 Rb
88

Zr

6h
0.21 ± 0.06
0.31 ± 0.07
0.18 ± 0.03
n.d.
0.58 ± 0.12
0.40 ± 0.06
1.07 ± 0.15
0.20 ± 0.10

12 h

24 h

48 h

0.42 ± 0.08
0.35 ± 0.07
0.18 ± 0.03
n.d.
0.89 ± 0.05
0.41 ± 0.03
1.69 ± 0.14
0.13 ± 0.02

0.36 ± 0.08
0.34 ± 0.02
0.14 ± 0.05
n.d.
1.16 ± 0.17
0.40 ± 0.04
2.36 ± 0.30
0.09 ± 0.03

0.52 ± 0.26
0.58 ± 0.06
0.12 ± 0.02
n.d.
1.54 ± 0.16
0.46 ± 0.08
2.59 ± 0.27
0.04 ± 0.01

Tissue uptake rate (%doselg) means the radioactivity percentage of injected dose per one gram of tissue.

that for the latter group. Figure 1 compares the brain
uptake rates of Sc, Mn, Co, Zn, Se, Rb and Zr tracers
in normal C57BL/6N mice at 6, 12, 24 and 48 h after
intraperitoneal injection. The uptake rate of the Se
tracer showed no significant time-dependent changes.
However, the uptake rates of the Sc, Mn, Zn and Rb
tracers increased with time, while those of the Co andZr tracers decreased. According to these results, it isevident that the metal ions examined in this work areeasily transported into the brain, and in addition thehigh retention of Se, Rb, Mn and Zn in the brain during a fairly long time suggests an active involvementof the elements in the brain function.
10.00.,,---- - - - - - - - - ,

Cl
0)

'"0

1.00

0)

'"
0)

.><

'c."
::>

~

j=

"1

• Co

~~

t

0.1 0

Sc
So

• Zr

Sc ----*- Mn --+-- Co ----+Zn -...- Se - . - Rb ~
Zr

-+--

0.01
0

10

20

30

40

50

Time after injection (h)Fig. 1. The uptake behavior of Sc, Mn, Co, Zn, Se,
Rb, and Zr by the brain at 6, 12, 24, and 48 h after
intraperitoneal injection of a multitracer solution.

References
1) S. Ambe et al.: Chern. Lett. 1991, 149.
2) S. Ambe et al.: Anal. Sci. 7, Suppl., 317 (1991).
3) S. Arnbe et al.: J. Radioanai. Nucl. Chern. 195, 297(1995).
4) R. Amano et aI.: J. Trace Elements Med. BioI. 10, 145(1996).
5) R. Amano et al.: Ambe, Ann. Clio Lab. Sci. 27, 358(1997).

127

RIKEN Accel. Prog. Rep. 31 (1998)

Metabolic and Biochemical Studies of Trace Elements inHypercholesterolemic Model Mice (I)R. G. Weginwar, S. Enomoto, R. Hirunuma, S. Ambe, and F. Ambe
Unregulated cholesterol production can lead to serious disease. Atherosclerosis (heart failure) is linked
to high levels of cholesterol in the blood, and particularly high levels of Low Density Lipoprotein (LDL)
bound cholesterol is a leading cause of death in industrialized societies. All steroid hormones in humans
are derived from cholesterol. Two classes of steroid
hormones are synthesized in the cortex of the adrenal
gland: mineralocarticoids, which control the reabsorption of inorganic ions by the kidney, and glucocorticoids, which help regulate gluconeogenesis and also reduce the inflammatory response. 1) The sex hormones
are produced in male and female gonads and the placenta. They include androgens and estrogens, which
influence the development of secondary sexual characteristics in males and females , respectively, and include
progesterone, which regulates the reproductive cycle infemales. In the present investigation we have studied
on the metabolic abnormality of trace elements suchas Be, Sc, V, Mn, Fe, Co, Zn, As, Se, Rb, Sr, Y,
and Zr in the different organs of normal and hypercholesterolemic (feeding cholesterol 5% diet to male
ddY mice for 2, 4 and 6 weeks) model mice.
Blood was collected in tubes from 4 to 5 animals ineach group after 12 hours fasting, and plasma was separated out by centrifugation for enzymatic assessments.
Total cholesterol (T -CH), High Density Lipoprotein(HDL-CH) and triglycerides (TG) in plasma were determined with enzymatic reagents, and Low Density
Lipoprotein cholesterol (LDL-CH) was calculated using the formula as described below.
LDL-CH = [(T-CH) - (HDL-CH) - (TG x 0.2)]

in hepatic Zn, Se and Sr uptake rate by cholesterol
intake is due to altered absorptive process or alterations in other aspects of their metabolisms. In thecase of kidney, almost all the elements were found to
be increased with plasma cholesterols. However, it isalready known that the mineralocorticoid hormones,
derived from cholesterol, regulate reabsorption of inorganic ions by the kidney. 1)
300

KIDNEY
2SO

i

i

128

.1

D

t

200

T

ISO ~

~

~

I

D

.E

t

~

100

T

'1*'

'*'

~

t

Q

0

0

.1

.1

t::.

t::.

so

t::.

o~
2.6

2.S

2.7

D
0

T·CH

'*'

TG

t::.

2.8

HDL·CH

LDL· CH

2.9

Zn Uptake (%doselg)

Fig. 1. Correlation between serum cholesterols and kidney
Zn level in hypercholesterolemic model mice.

300

LIVER

2SO

I

T

D
.1

~
§

150

~

~

t

T

0

~

0

200

c

E

T-CH, TG and LDL-CH were found to be significantly increasing in plasma of hypercholesterolemic
group in feeding period, while HDL-CH increased only
by 10% with respect to control group. vVe have observed a positive correlationship between T -CH and
LDL-CH in plasma and hepatic uptake of Fe, Mn, Co,
As, Cr , V, Sc, Be, Zr, Y, Nb, and Ru for hypercholesterolemic mice.
The analyses showed that the T -CH and LDL-CH
in plasma were positively correlated with Zn in kidney (Fig. 1). On the other hand, Zn uptake in liver
were negatively correlated (Fig. 2) , but no correlation
was found with HDL-CH and TG. Similar results werealso observed for Se and Sr in liver as well as in kidney. It has been reported that glutathione peroxidase
activity decreased with induced hypercholesterolemia
in rabbits but it is not yet known whether the decrease

T

'*'

'1*'

~
0

Q

.1

100

t::.

I:

J:

T

t
0

.1

¥

t::.

so

t::.
0
4.25

T
D

4.S

4.7S

t::.

D

T·CH

0

HDL-CH

'*'

TG

t::.

LDL·CH

S.25

Zn Uptake (%doselgl

Fig. 2. Correlation between serum cholesterols and hepatic Zn level in hypercholesterolemic model mice.

Thus, our results provide a definite evidence thatcholesterol and lipid concentration in the body can significantly involve in the metabolism of trace elements.
References
1) A. L. Lehninger, D. L. Nelson, and M. M. Cox: in Principles of Biochemistry, Worth Publishers, second edition, New York, (1993), p. 680.

RIKEN Accel. Prog. Rep. 31 (1998)

Metabolic and Biochemical Studies of Trace Elements inHypercholesterolemic Model Mice (II)R. G. Weginwar, S. Enomoto, R. Hirunuma, S. Ambe, and F. Ambe
The radioactive multitracer technique was applied
for simultaneous evaluation of bio-behavior of trace elements in different organs of the normal and hypercholesterolemic model mice. The distribution of traceelements (Be, N a , Sc, V , Cr, Mn, Fe, Co, Zn, As, Se,
Rb, Sr, Y, Zr, Nb and Ru) in 8 organs (liver, kidney,
brain, muscle, lung, spleen, bone and testis) and inblood was examined by using the multitracer solution
prepared from the Ag target irradiated by heavy ions.
The tissue distribution was evaluated by ,-ray spectrometry in terms of the radioactivity percentage of
injected dose per gram of tissue. In this paper, only
results of blood and liver are reported and discussed
as typical examples.
Figure 1 shows the uptake rate of various trace elements by blood after 24 hrs of multitracer injection into the normal as well as 2 to 6 week-fed cholesterolemicmice. A positive correlation was found between the
uptake rate of Sr and As in to blood with cholesterol
feeding. On the other hand, a negative correlation occurred between the uptake rate of Zn, Co, N a, Be,
V, Cr, Rb, Zr and Ru in to blood with cholesterol
feeding. The uptake rate of Fe, Sc and Nb increasedin the 2 and 4 week-fed mice compared to the normal ones, but decreased in the 6 week-fed mice. Incase of Se, uptake rate was higher in cholesterolemic
mice, compared to normal ones, but cholesterol dose
dependence was not observed. It has already beenreported l ) that, plasma superoxide dismutase activity increased by feeding cholesterol to rabbits, while
glutathione peroxidase activity decreased. This may
Ru

24h BLOODo Control

Nb

Zr
y
Sr
Rb

Se

Q

2week

III

4week

III

6week

'" As
C

e

qJ

ril

Zn
Co
Fe
Mn
Cr
V

Sc
Na

Be

0

0.5

1.5
2
Uptake rate (%dose/g of tissue)

2.5

be the possible reason for different metabolism of Se.
In the liver of hypercholesterolemic mice at 24 hrs after the multitracer administration (Fig. 2), the uptake
rate of Be, Sc, Zr , Y , V, Rb, Fe and Nb was observed
to be much higher compared to normal mice, and increased with cholesterol feeding period. Conversely,
biologically important elements such as Zn, Se and Sr
uptake rate was found to be decreasing with feeding
period of cholesterol.
24h LIVER

o Controlo 2week

III

4week

III

6week

_ _. . . . . ------1

o

7.5
5
2.5
Uptake rate (%dose /g of tissue)

10

Fig. 2. Uptake rates of various elements in liver at 24 hrs
after injection in the normal and hypercholesterolemicmice.

We observed many fat granulations and fiberizationin liver of hypercholesterolemic mice, and it has been
already reported that, the bone seeking elements like
Be, Sc, V, Zr, Y, Nb and so forth are stored in the partof fiberization. Such a change was assumed to be generated by hepatopathy in the cholesterolemiC mice, andthe uptake rate of these bone seeking elements is suggested to increase by this reason. Also, cholesterolemia
seems to have some specific effects on the metabolism
of some elements with high valency or some enzymes
requiring inorganic elements as cofactors.
In literature, certain influence of cholesterol on themetabolism of copper, selenium, iron, zinc and magnesium is described, but the nutritional influence ofcholesterol metabolism on various trace elements under similar experimental conditions is not yet studied.

3

References
Fig. 1. Uptake rates of various elements in blood at 24 hrs
after injection in the normal and hypercholesterolemicmice.

1) E. D . Silva, P. Moriel, Y. Chang, and D. S. P. Abdalla:
Biochem. Mol. Bio. Int. 36, 679 (1995).

129

RIKEN Accel. Prog. Rep. 31 (1998)

Metabolic Study of Trace Elements in Se-Deficient Rats (II)R. Hirunuma, N. Sotogaku, K. Endo, S. Enomoto, S. Ambe, and F. Ambe
A number of studies on the role of Se in biochemistry are found in literature. It is very interesting andimportant to clarify the distribution of trace elements
in various organs of Se-deficient rats. In the present
study, the uptake and distribution of trace elements
in Se-deficient rats were examined by the multitracer
technique which can evaluate the behavior of many elements under the same experimental condition.
Multitracer solutions containing various radioisotopes were pre'p ared from a Ag target which was irradiated with 14N or 16 0 beam of 135 MeV/nucleon extracted from RIKEN Ring Cyclotron. After chemical
separation, this multitracer was dissolved in a physiological saline solution. Mother (Wistar) rats had been

fed with Se-deficient diet (produced by Oriental Yeast
Co., LTD.) since their 14th day of pregnancy until theweanling period of their baby rats. The weanling malerats were separated from their mothers, and were fed
with Se-deficient diet until the age of 12 weeks. A
tenth ml of saline contained the multitracer was injected in to the tail vein of each rat. The Se-deficientand normal rats were sacrificed at four different times
after injection, and the radioactivities in their organs
and blood were determined by ,-ray spectrometry.
The characteristic results obtained on some of theelements (As, Fe, and Sc) in the liver are shown in
Fig. 1. In the liver, the uptake of As, Fe, and Sc of
Se-deficient rats was larger than that of normal ones

40...,--------,

10.0...,--------,

40.,---------,

~ 7.5

~ 30

~ 5.0

<II

<II

] 20
c.

] 20
c.

c.

;;J

2.5

;;J

20 40 60
Time (hr)

80

~ 30

10

;;J

o

20 40 60
Time (hr)80

1020 40 60
Time (hr)80Fig. 1. Time dependence of the uptake of As, Fe, and Sc in the liver of normal ()( )and Se-deficient rats (.) .
at 72 hrs after injection.
The following two reasons are suggested for the accumulation of As in the liver of Se-deficient rats. The
first reason is the hypofunction of As methylation in
the liver of Se-deficient rats, As is in a competitive relationship with Se, and Se intoxication is preventable
by AS. 1,2) Inorganic As, which is especially toxic toanimals in this form, is detoxicated by methylation in
the liver, and this methylated As is excreted throughurine. Because the chemical form of As is As0 3 - inour multitracer, the accumulation of As in the liver of
Se-deficient rats can be interpreted as a result of thedepression in effectiveness of the As methylation. The
second reason is the decrease of As excretion to bileon account of Se-deficiency. Arsenic enhances Se excretion to bile, while Se also enhances As excretion to
bile. 3 ,4)The accumulation of Sc and Fe in the liver increased
with time in the normal and Se-deficient rats. Interestingly, the uptake behavior of Sc and Fe in the liverof normal rats was similar to that in the liver of Sedeficient rats. Iron is, of course, one of the essential
elements in living organisms, whereas for Sc no beneficial role has been reported. The reason for the similar
uptake behavior between Sc and Fe is considered dueto the similarity of their ionic radii (0. 73A for Sc 3 + and
130

0.64A for Fe 3 +) and their same ionic valence (Sc 3 + andFe 3 +).
No difference was observed in the uptake behaviorof most of bone seeking elements such as Ca, Sr, andY between normal and Se-deficient rats. On the contrary, bone uptake of Zr was clearly different between
Se-deficient and normal rats. Although Zr is classified into the bone seeking elements, there are only few
reports on behavior of Zr in animals. The present experiment showed that Zr behaves in a characteristic
way different from other bone seeking elements. Thismight be due to its unique chemical form of Zr0 2 + in
the aqueous medium.
Selenium is known to be in a competitive or synergistic relationship with several metals. From the present
result on Sc and Zr, it was newly elucidated that there
is some interaction between these elements and Se.
References
1) A. L. Moxon: Science 88, 81 (1938).
2) A. L. Moxon and K. P. DuBois: J. Nutr. 18, 447 (1939).
3) O. A. Levander and C. A. Baumann: Toxicol. Appl.
Pharmacol. 9, 98 (1966).
4) O. A. Levander and C. A. Baumann: Toxicol. Appl.
Pharmacol. 9, 106 (1966).

RIKEN Accel. Prog. Rep. 31 (1998)

Influence of pH on Release of Various Trace
Elements from Transferrin
N. Sotogaku, K. Matsumoto, K. Endo, R. Hirunuma, S. Enomoto, S. Ambe, and F. Ambe
Transferrin, iron-binding protein, is composed of asingle 80 kDa polypeptide chain with two domains.
Each domain has a site capable of binding various
metal ions other than Fe 3 + ions. Transferrin functions
to transport iron in mammalian, i.e., it transfers Fe 3 +ions from the absorption site to the storage and/or
utilization sites through body fluids. At extracellular
pH7.4, iron-loaded transferrin binds strongly to its receptor on plasma membrane. Then, Fe 3 + ions released
at intercelluer endosomes at low pH (approximately
5.5) .1) The detailed chemical mechanism by which ironis removed from the protein is unknown, although thebiological process involved in iron release at low pH inan endosome by endocytosis has been characterized.
In addition, it is known that transferrin is involved in
the metabolism of other metal ions, such as AI, Cr,
Mn, Co, Cu, Zn, Ga, and rare earth elements (REEs)
which are either trace or toxic elements. 2 ) Althoughbinding and release of iron (Fe) ions have been studied, those of other metal ions have not been studied indetail till today. In the present study, we report the
pH dependence on the release of metal ions (Fe, Sc, Y,
Zr, Hf, Ce, Eu, and Gd) from transferrin by means of
the multitracer technique.
A multitracer was prepared from a piece of gold or
silver target. The preparation of the multitracer solution was followed by the established procedure. 3 ) Apotransferrin was purchased from Wako Pure Chern. Ind.,
Ltd. and was used without a further purification. A
solution of the metal-ion (multitracer) bound transferrin was prepared by adding the buffer solution (O.OIM
Tris/HCI; pH8.0) (Tris; 2-amino-2-hydroxymethyl-l,3propanediol) containing a multitracer (50 p'!) to theapotransferrin solution. The solution was mildly incubated at 37°C for 24 hr. For experiment on pHmediated release of various metal ions from transferrin, the solution was dialyzed for 48 hr against thebuffer solutions in the pH range of 7.4 to 3.0. The
buffer used for various pH ranges were: pH7.4 to 6.0,
O.OIM HEPES/NaOH (HEPES; N-[2-hydroxyethyl]
piperadine-N'-[2-ethanesulfanic acid]); pH5 .5 to 3.0,
sodium acetate/acetic acid. All buffers contained 0.2M
of N aCl. After dialysis, the mixture was ultrafilteredusing Molcut II (fractional M.W. 10,000; Millipore
Corporation). The , -ray spectra of the filters were
measured by a pure Ge detector, and were comparedwith that of the standard multitracer solution.
Figure 1 shows the percentage of radioactivities ofFe, Sc, Y, and Ce, bound to transferrin after dialysis,
assuming those at pH8.0 as 100%. Stability of themetal ions and transferrin has been reported in termsof the pH50 value, that is the pH at which 50% of metal
ions release from the protein. 4 ) The pH50 values were
found to be 4.6 for Sc, 7.4 for Y, 5.5 for Fe, and 6.9 for
Ce in the present study.
Correlation between the pH50 and ionic radius is ten-

100.-----------------------~~

=
=

75

~

50

~
Q
~

-----<>-- Fe~~- - Ru25-----Q--

Cr

_Zn

pH

Fig. 1. The pH-dependent release of metals.

tatively shown in Fig. 2. together with the values for
Hf, Zr, Gd, and Eu. The chemical forms of the tracers were assumed to be Sc 3 + , y 3 +, Ce 4 +, Eu 3 +, Gd 3 +,Zr 4 +, and Hf4+. The ionic radius of the metal ions
is: Sc 3 +, 0.68 A; y 3 +, 0.88 A; Ce 4 +, 0.92 A; Eu 3 +,0.95 A; Gd 3 + , 0.94 A; Hf4 +, 0.71 A; and Zr 4 +, 0.72
A.5) The stability of transferrin metal complex depends markedly on synergistic anions, and bicarbonate(or carbonate) anions serve this function in a biological system. 6 ) As mentioned at the beginning, transferrin has two chemically active domains. It has beenreported that the C-terminal has three more cystine
bridges and is more acid-stable than the N-terminalsite. 7 ) Studies on the effects of pH for the release of various metal ions from each terminal site are in progress.

y _ 8.385 •• 0.462,,_ 0.859

..

Eu

c•

•

Sc

•

4+-----.-----,-----,---~

0.6

0.7

0.8

0.9

Ionic radius (A)Fig. 2. Correlation between pH50 value and ionic radius.

References
1) H. Li et al.: Eur. J. Biochem. 242, 387 (1996).
2) L. Messori et al.: Metal-Based Drugs. 1, 161 (1994).
3) S. Ambe et al.: J. Radioanal. Nucl. Chern. 195, 297(1995).
4) C. L. Day et aI.: J. BioI. Chern. 267, 13857 (1992).
5) N. T. Topp et aI.: Chemistry of the Rare-Earth Elements (in Japanese) (Kagakudouzin, Tokyo, 1995).
6) M. S. Shongwe et al.: Biochemistry. 31, 4451 (1992).
7) S. A. Kretchmar et al.: J. Am. Chern. Soc. 108, 6212
(1986).
131

RIKEN Accel. Prog. Rep. 31 (1998)

Affinity of Bio-Trace Elements to Cell Component:
In vitro Study Using Multitracer
K. Matsumoto, N. Sotogaku, K. Endo, S. Enomoto, S. Ambe, and F. Ambe
The metabolism of manganese (Mn), cobalt (Co),zinc (Zn), copper (Cu), and selenium (Se) in a biological system has been studied in relation to the enzyme
activity by a number of workers.
Recently, the multitracer technique has been developed and applied to the studies on distribution of the
bio-trace elements in rat organs. We found that iron(Fe) uptake enhanced in the liver of Se-deficient Wistar rats. I) The result suggested that alternative interaction of Se and Fe is operating in a living body. Since
Se is the central ion in glutathione peroxidase (GSHPx) and works as a reductant of hydrogen peroxide, it
could be expected that Fe took the place of activityof anti-oxidative stress by Se. However, the mechanism of the interaction and distribution of the traceelements in a cell level have not yet been clarified. To
examine the possibility of the interaction, it is necessary to obtain the distribution of the elements in cellcomponents such as nucleic acid, proteins, lipid, andsugars.
DNA is an essential element that supervises the genetic information for living cells. Therefore, DNA
modification or fragmentation by the reactive oxygenor other free radical species and by ligation of the metal
ions might cause cell death, mutagenesis, or carcinogenesis. In order to examine possibility of distributionof metal ions in nucleic acid and in order to study interaction of metal ions within in vivo redox system, westudied the affinity of bio-trace metal ions to the normal and Se-deficient rat's DNA from liver, lung, andcolon.
The Se-deficient Wistar rats and normal Wistar rats
were sacrificed by decapitation. Subsequently, the major organs were excised. Tissues were immediately
frozen and kept at -80°C until DNA isolation. Liver,lung, and colon DNA was isolated by Kirby's method 2)
and prepared with concentration of 1 mg/ml by TrisHCI (pH 8.0) buffer.
The 10 J.LI of multitracer solution were added in to
DNA solution. Then, the mixed solution was mildly incubated at 37°C for 60 min. After the incubation, themixed solution were ultra-filtrated. The ,-rays fromthe multitracer remained with DNA on the filter were
measured with a pure Ge ,-ray detector. The affinity
relative to the standard multitracer solution was computed from ,-ray energy spectra. Although the multitracer solution used in this study included Fe, Zn, Co,
Mn, Se, Cr, As, Sr, Na, Ca, Rh, Zr, Be, Ru, Rb, Sc,
and Y, we analyzed Fe, Zn, Co, Mn, and Se which are
related with bio-redox regulation systems in order to132clarify our purpose.
Figure 1 shows the affinity of metal ions to DNA.
In normal rats, the affinity of Se was relatively low inthe liver, lung, and colon. Affinity of metal ions to theliver and lung DNA were almost same. However, inthe liver and colon DNA, affinities of Mn, Co, and Zn
to liver DNA were significantly low, while in the lungand colon DNA, affinities of Mn and Zn to lung DNA
were significantly low. In Se-deficient rats, affinity of
Fe was relatively high in DNA of these three organs.
No significant difference within organs was found. Collectively, the affinities of the metal ions (Mn2+, Co 2 +,and Zn2+) to Se-deficient rats DNA were relatively low
compared with normal rats.
(A);;::::::::::::c

Se . . . . .
~~

(B)

L'
Ive,

I

~en~,:,:,,:·:·:·i·,····: .
o 25 50 75 100 125.......!
.::::::?
s:::::=::::::•.... '..:......

! Lo

100 125

zn~~

Se
Co

URS

75

100 125

I

Un ?S::Q::::::\"':
25

50

75

75 100 125~~ • . . ."........'COlonl¥~ ¥.:00:·:·:·:·:·:·:·::
Mn ==.:.:.:.:.:.:.1
1

I

o

25

50

75

100 12575

100 125

Fig. 1. Relative affinity of bio-trace elements to the normal(A) and Se-deficient (B) rat's DNA.

As a result, we suggested that affinity of metal ionsdecreased with DNA modification by reactive oxygen
species in Se-deficient rat's DNA. A possible reason
will be that the binding site of metal ions on DNA
was blocked with modification by the reactive oxygen
species itself or by the products of lipid peroxidationsuch as malondialdehyde and 4-hydroxynonenal. Relatively low affinity of the liver and lung DNA can be
explained by this hypothesis: i.e., liver and lung areusually subjected to oxidative stress because liver isthe place of metabolisms .and because lung is usually
exposed by air.
References
1) R. Hirunuma, N. Sotogaku, K. Endo, S. Enomoto, S.
Ambe, and F. Ambe: RIKEN Accel. Prog. Rep. 30,
110 (1997).
2) K. S. Kirby: Biochem. J. 66, 495 (1957).

RIKEN Accel. Prog. Rep. 31 (1998)

Multitracer Study on Binding Activity of Various
Trace Elements to Metallothionein
J. Chou, S. Enomoto, S. Ambe, and F. Ambe
The metallothionein is a small intracellular
protein. 1) It is characterized by the following features:a low molecular weight , high metal content, and absence of aromatic amino acids . Metallothionein is involved in the normal metabolism of Zn and Cu. Its
outstanding function has been described as detoxifying
heavy metals. Cadmium, Zn and Cu are usually associated with metallothionein in vivo, but a wide rangeof other metals such as Ag, Co, and Ni can not binds
to the proteins in vivo but can bind to the proteinsin vitro.2) In the present work, we have studied thebinding activity of a large number of trace elements
to metallothionein in vitro and pH-dependence on thebinding activity using a multitracer technique. It is reported for the first time that metallothionein can bindsimultaneously with additional metals.
The interaction between metallothionein and multitracer in vitro at neutral solution were simultaneously
determined using the multitracer technique. After element assignment based on the ,-ray energy and halflife, the binding percentage of 14 kinds of trace elements was obtained. The results are shown in Fig. 1.
We found that for met allothionein , more additional
metals could also be accommodated. The elementsbound to metallothionein can be divided into the fol-

100.-----------------~------------_.

~u

OIl

75

S

~

~

~

50

00
~

:0
Q

25

~

o
Be Na Sc V

lowing four groups based on the classification of theperiodic table:(1) For alkaline metals, such as Na and Rb, the binding percentage is zero. The results indicate that alkaline metals can not bind with metallothionein.
(2) For alkaline earth metal, the data suggest that Be
can bind with metallothionein more than Sr, illustrating that the binding activity of Be to metallothioneinis stronger than that of Sr. Thus, for alkaline metals,
the binding activity to metallothionein decreases withincreasing ionic radius.
(3) For transition metal elements, such as, Sc, V,
Mn, Co, Zn, Zr, Nb, Hf and Ru, it was observed that
all these transition metal elements had different binding percentages to metallothionein. The results illustrate that transition metal elements can bind to metallothionein. Zinc has the highest binding percentage,
while Zr, Nb and Hf have higher binding percentage.
Scandium, V, Mn, Co and Ru have small binding percentage.
(4) For group VI-A, such as Se, the binding percentage to metallothionein was also obtained. Se has highbinding percentage, thus it can bind to metallothioneinstrongly. Because the binding percentage of Se is nearto the value of Zn, it was concluded that the binding activity of Se was similar to that of Zn at neutral
solution.
It was also found that the binding activity of theseelements to metallothionein was affected by the pH in
the solution. Except Sc, Nb, Zr and Hf, the binding
activity of other elements increased with increasing pH
solution. For Sc, Nb, Zr and Hf, the binding activity
increased with increasing pH solution at the pH lower
than 5.3, then decreased at the pH lower than 7.4 andincreased again at the pH higher than 7.4.

Mn Co Zn Se Rb Sr Zr Nb Ru Hf

Elements

Fig. 1. The binding percentage of 14 kinds of elements
binding to metallothionein at pH of 7.4. Each datum
in the figure represents the mean values ± standerd
deviation calculated from at least three samples.

References
1) J. F. Riordan and B. L. Vallee: in Methods in Enzymology Vol. 205, Metallobiochemistry, part B. (Academic
Press, 1991), p. 11.
2) H. Li and J . D. Otvos: Biochemistry 35, 13929 (1996).

133

RIKEN Accel. Prog. Rep. 31 (1998)

Multitracer Study on Coordinating of the Rare-EarthElement with Metallothionein
J. Chou, S. Enomoto, S. Ambe, and F. Ambe
The rare-earth element (REE) has been shown to
be involved in many important biological function andis considered to be harmful, interrupting physiological
functions. REE can bind with some proteins, but sofar, there is no report about the binding between REE
and metallothionein which is able to bind a number ofmetal ions. In present report, multitracer was used to
study the binding or coordinating between REE andmetallothionein.
The binding between REE and metallothionein in
vitro at the neutral solution was determined using multit racer technique. The coordinating coefficients (Kd)between REE and metallothionein with ionic radius
are shown in Fig. 1. The results indicated that metallothionein can coordinate with some REE. Amongthe tested REE, Eu has the highest binding percentage and Lu has the lowest one. The metallothionein
usually contains 61 or 62 amino acids, 20 of which areconserved cysteine residues. It has an unique distribution of cysteinyl residues in the amino acids sequence toaccommodate the formation of metal-thiolate clusters,by which the metal ions are bound to metallothionein.
But in general, Lanthanides coordinate with the unprotonated carboxyl group of amino acids in the protein. The major ligand for REE ions on proteins is the
carboxyl group. Thus, for REE, they are not similar
to the transition metals which bind to cystines in themetallothionein 1) and are considered to bind to unprotonated carboxyl group of amino acids. It was reported
that the coordinating of the peptide, Cys-Tyr-lle-GluAsn-Cys-Pro-Leu-Gly-NH 2 , was studied by 1 H-NMR
spectroscopy with Yb 3 +, and that lanthanides wereshown to coordinate with the carboxyl group of Glu
and with the carbonyl side chain of Asn. 2 )The pH dependence of binding percentage of REE
to metallothionein was determined. The binding percentage is dependent on the pH solution. The coordinating coefficients of REE to metallothionein withpH are shown in Fig. 2. The coordinating coefficientsdecreased with decreasing pH. At pH of 3, for all
the tested REE, the binding percentage decreased to134

0.5-r-------------.

0)E

E 0.25~~Ce

O+-----.r-------~--~

0.8

0.9

Ionic radius (A)Fig. 1. The coordinating coefficients (Kd) with radiusof rare-earth ions at pH of 7.4. Each datum in the
figure represents the mean values ± standerd deviation
calculated from at least three samples.

m:O ':D ':D ':D~z • ••

~:D
2

•

,.

z",

z...

:0:0
l

<4

2

, .

4

6

z...

•

pH

Fig. 2. The coordinating coefficients (Kd) versus solution
pH.

zero. At low pH, the carboxyl group will bind withhydrogen ion.
References
1) H. Li and J. D. Otvos: Biochemistry 35, 13929 (1996).
2) R. Walter, C. W. Smith, and K. P. Sarathy et al.: Int.
J. Pept. Protein Res. 17, 56 (1981).

RIKEN Accel. Prog. Rep. 31 (1998)

Transfers of Trace Elements from the Placenta
to the Fetus of Pregnant Rat
J. Chou, S. Enomoto, R. Hirunuma, S. Ambe, and F. Ambe
Trace elements are essential for human body for theirnormal growth and development, especially for a pregnant mother, and the same is true for a fetus. The
placenta functions as the barrier between fetus andmother: providing regulation of heat exchange, respiration, nutrition, and excretion for the fetus. Before
birth, fetuses will accumulate enough trace elementsfrom their mother.I) Limited information is available
on the transfers of trace elements from their mothers to
the fetuses. 2 ) In this study, the multitracer technique
was applied to study the transfers of trace elements via
placenta to the fetus.
17 day pregnant Wister rats were used for the experiment. The pregnant rats were injected with multitracer solution and sacrificed at 24 hours after injection. The chemical forms of the tracers are Be 2 + , N a + ,
2
3
2
2
3
2
- ' Se0 3- ' Rb+ ,VO+
2 , Mn + , Fe + , Co + , Zn + , As0 4
2
2
Sr + and Ru + in the solution to mice. Figure 1 shows
the uptakes of 13 kinds of trace elements in the placenta and fetus. In the placenta, the V has the highest
uptake among all the trace elements. Then Se, Na, Fe,
Ru, Zn, Zr and Rb have higher uptakes in the placenta.
Manganese, Co and As have relatively lower uptakes
than the elements mentioned above. Strontium has thelowest uptake in the placenta. No radioactivity of Be
appeared in the placenta, and there is no uptake of Be
in the placenta.
2~-----------------------------------.

D

placenta

•

retus

Sr

Zr

T

o

Be

Na

V

Mn

Fe

Co

Zn

As

Se

Rb

Ru

Elements

Fig. 1. The uptakes of trace elements in fetuses and placentas. The uptakes are shown in terms of percentageof the injected dose to the weight of tissues.

For fetus, the uptakes of trace elements were different from those in placenta. Iron has the largest uptake
in the fetus, then Na, Zn, Mn and Se. The Sr, Co,
Rb and V have relatively small uptakes in the fetus.

Arsenic, Zr and Ru have the lowest uptakes, especiallyfor Zr and Ru the uptakes were near to zero.
Compared to the uptakes in the placenta and fetus,
the uptakes of Zn and Na are similar each other. For
other elements, the uptakes in placental tissue were
found to be different from those in fetus. The uptakesof V, As, Se, Zr and Ru in the placenta were far higher
than those in the fetus. The uptakes of Co and Rb
in the placenta were a little higher than those in thefetus. However, the uptakes of Mn, Fe and Sr in theplacenta were less than those in the fetus.
Because the trace elements for fetus must be obtained from their mother across placenta, the uptakesof trace elements in fetus and placenta should reflect
the transfers of trace elements from placenta to fetus.
The uptakes of Fe, Mn and Sr in the fetus were larger
than those in the placenta, illustrating that more thanhalf of these elements in the placenta were transferred
to fetus. For Mn, two thrid (2/3) of Mn was transferred to the fetus. This suggests that the transfers ofFe, Mn and Sr from placenta to fetus were very rapid.
The transfer of Fe from mother to fetus across the placenta maybe relating to the transferrin and the fetaliron is derived from maternal transferrin.
The uptakes of Na and Zn in the placenta were similar to those in the fetus, reflecting that half of them inthe placenta were transferred to the fetus. The transfers of Na and Zn were also fast. The uptakes of Co, Se
and Rb in the placenta were larger than those in thefetus, indicating that less than half of them in the placenta were transferred to the fetus. For Se, one thridof Se was transferred to the fetus. However, although
the uptake of V in the placenta was the largest, the uptake in the fetus was very small. Only one twentieth(1/20) of V was transferred to the fetus across the placenta. This data indicates that the transfer of V wasvery slow, but V was able to penetrate the placenta
and enter the fetal body. The same phenomena wasobserved in the uptakes of As, Zr and Ru. Very few
uptakes of As, Zr and Ru were observed in the fetus,
and the transfer of them from the placenta to the fetus
was very slow.
References
1) N. I. Ward, T. D. Macmahon, and J. A. Mason: J.
Radioanal. Nucl. Chern. 113, 501 (1987).
2) S. Honey, G. I. Dhall, and R. Nath: J. Trace Elem. Exp.
Med. 5, 165 (1992).

135

RIKEN Accel. Prog. Rep. 31 (1998)

Uptake and Translocation of Sr, Tc, and Cs
in Soybean Plants
T. Shinonaga, S. Ambe, and I. Yamaguchi
The uptake and translocation of radionuclides of Sr,
Tc, and Cs in the soybean plants were studied over360 h after the administration of a multitracer to soil.
Leaves, stems, and fruits were collected at every node
at appropriate intervals as samples for ')'-ray measurements. The uptake amount (%/ g) in most of the leaves
and stems collected from the nodes increased up toaround 200 h after the administration of the multitracer, and then decreased with time. In the case offruits, such tendency was observed for the uptake of
Cs as shown in Fig. 1.
The total amount (%/plant) of Sr, Tc, and Cs in thepods increased with the cultivating time, while that of
Sr and Tc in the seeds increased only slightly. The uptake amount of Tc in the pods was large, but translocation of Tc from the pods to the seeds was only alittle. The uptake amounts of Tc by the leaves, stems,
and pods were larger than those of Sr and Cs but theratio of the uptake amount of Tc in the seeds to thatin the pods was smaller than that of Sr and Cs. The
fact that the translocation of Tc from the pods into theseeds is less than that of Sr and Cs shows a different
selectivity for these elements.
The behavior of elements in the leaves, stems, andfruits of each node was mathematically analyzed withthe second order function, Ae = c + kl t + k2 t 2 , 0 < t :::;
360; where A is the uptake amount of the element, ein each part of plants, c the constant, t the cultivatingtime after the multitracer was administered, and kl
and k2 the coefficients of t and t 2 , respectively. I) The
fitting curves are shown in Fig. 1. This equation enables us to predict the time when the element uptake

136

Sr

Cs

Tc

Leaf

Stem

.Gd0J . ~
0

u

Q

.

u

: : .

1

0.1

....

o

0

0

lOG

300

400

r····.. ..

0.13

U1

1····· . .. 0'"

100

1.. ...•

0

100

lOCI

JOG

0.01

_

:

/,/0

:.\.

Fruit
::::

/0

0

100

lOG

:JOO

_

Cultivating time (h)Fig. 1. Change of the uptake amount of Sr, Tc, andCs in leaves, stems, and fruits at the sixth node as afunction of the cultivating time with the multi tracer.
The error bars indicate the difference between two raw
data. If the error bar is not shown, the datum is single.
In the case of Tc-leaf and Tc-stem, the error is within
the symbol, if error bar is not shown.

reaches the maximum.
References
1) T. Shinonaga, S. Ambe, and 1. Yamaguchi:
dioanal. N ucl. Chern. in press.

J. Ra-

RIKEN Accel. Prog. Rep. 31 (1998)

Multitracer Study on Uptake of Elements by Turnip
S. Ambe, T. Shinonaga,*l T . Ozaki, S. Enomoto, H. Yasuda,*2 and S. Uchida*2
The absorption selectivity, a parameter of an uptake
model l ) for radio nuclides by plants, was determined bya multi tracer technique. 2) The selectivity S is defined
as follows:roots. The selectivity of Ca and Sr for the leaves
was higher than that for the roots. On the contrary,
Be showed low values of the selectivity for the leaves,though large values were observed for the roots.

A = STCo
15T"Y"""---------,

where A is the total amount of a radio nuclide absorbed by a plant during the experimental period, T
the amount of transpiration, and Co the initial concentration of the nuclide. S of various elements fromBe to Re was determined by changing Co of nutrient
solutions.
The nutrient solution of every 1 dm 3 contained 2.0 mmol of MgS0 4 · 7H 2 0, 4.0 mmol ofCa(N0 3 h ·4H 2 0, 8.0 mmol of KN0 3 ) 1.4 mmolof NH 4 H 2P0 4, 0.059 mmol of Fe-EDTA, 4.8 p,molof H 3 B0 3 , 76 nmol of ZnS04' 7H 20, 910 nmol of
MnCh . 4H 20, 20 nmol of CUS04 . 5H 20, and 1.4 nmolof (NH4)6Mo7024 ·4H 20. A multitracer solution wasadded to the nutrient solution, and pH of the solution was adjusted to 5.5-6.0 with a 1 mol dm- 3 KOH
solution. The solution and the ones diluted to 1/2,
1/5, 1/10, and 1/20 with distilled water were used for
culturing of the plant, and their concentrations wereexpressed by the electric conductivity which is linearly
related to the ion concentration in a solution. The
electric conductivity of the original nutrient solution
was 2.3- 2.5 mS/cm.
Turnip (Brassica campestris L. var. Komatsuna)seedlings were hydroponically cultured on the nutrient solution in a plant-growth chamber at 23°C. The
plants which were cultivated for 20-30 days were transplanted into a nutrient solution containing the multitracer. After the one-day cultivation, the plants were
harvested and then they were separated into leaves androots. The dried samples were subjected to the ,-raymeasurement with Ge detectors.
The selectivity of elements studied was, in general,found to decrease with an increase in the concentration of the nutrient solutions. As for alkali elements, the selectivity for the leaves was higher thanthose for the roots in the entire concentration rangeof the nutrient solution. The selectivity decreasedin the order as K 2: Rb > Cs > N a in the leaves andRb 2: K > Na 2: Cs in the roots.
The selectivity of alkaline earth elements also decreased along with the concentration in a similar fashion to that of alkali elements as shown in Fig. 1.
The selectivity decreased in the order as Ca ~ Ba ~Sr > Be in the leaves and Be > Ba > Sr ~ Ca in the*1*2

GSF-National Research Center of Environment and HealthInstitute of Radiation Protection
National Institute of Radiological Sciences.

o leaves- roots

I.

10

.-,

Be

:

i ,

5

-

,

Ca
10

8
5

0

~
U
CD

"iii

0

-8

r: !

0

15r-------~

UI

Sr
10

0

15.-------------,

Sa

o
~

10

0

"'.

!e0

5

8~

i

: II

o-l--_--......:i=--~-l)!L.;I____lo3Electric Conductivity (mSlcm)

Fig. 1. Relation between the selectivity of alkaline earth
elements and the concentration of nutrient solution inturnip.

The radioactivities of V, Cr, Fe, As, Rh, Ag, Sc, Y,
Pm, Eu, Gd, Ir, and Pt in the leaves were below thedetection limits, while their significant amounts were
found in the roots. Many elements which are not regarded as useful elements for the plant growth wereretained on the roots, not giving rise to their translocation to the leaves. However, Re has exhibited a contrasting result. That is, much more Re was accumulated in the leaves than in the roots.
By using the selectivity obtained in this work, atransfer factor of radionuclides can be estimated forthe plants.
References
1) H. Yasuda and Y. Inoue: Hokenbutsuri 29, 295 (1992).
2) S. Ambe et al.: J . Radioanal. Nucl. Chern. 195, 297(1995).

137

RIKEN Accel. Prog. Rep . 31 (1998)

Metabolism of Trace Elements in Euglena gracilis
Using the Multitracer Technique
R. G. Weginwar, M. Katayama, S. Ambe, S. Enomoto, T. Ozaki, and F. Ambe
Incorporation and excretion of multitracers in the
Euglena gracilis cultured in two kinds of conditions
were examined as follows.
Green Euglena was treated with streptomycin to obtain yellow Euglena, deficient of chlorophylls. Bothgreen and yellow Euglena cultures were grown ina Koren-Butner medium l ) at 27-30 cC. The cells
were centrifugally separated, washed thoroughly in a
medium without trace nutrients, and suspended in anincorporation medium consisted of: ammonium sulfate, ammonium bicarbonate, potassium phosphate,magnesium carbonate, calcium carbonate, and vitamin Bl and B12.
After addition of the carrier-free multitracer mixture, the incorporation experiment was initiated at
30 cC. At such time intervals as indicated in Figs. 1
and 2, a small aliquot of the samples was extracted,
cooled down in ice, and centrifuged. The cell fraction
was washed with ice-cold medium thoroughly. The radioactivities in the washed cells were measured by thehigh purity Ge gamma detector, and were expressedby percentage as compared to the total amount in themedium at the zero time. The remaining portion of
the cell suspensions was centrifuged and the cell fraction was washed thoroughly with an ice-cold complete
medium and used for excretion experiments. The excretion experiment started by suspending the cells in
a complete medium at 30 cC. The extracted samples
were cooled down rapidly, and the cells were centrifugally separated from the medium. After the washingof the cells thoroughly, their radioactivities were determined by the Ge gamma detector.
The measured incorporation rate of the ions of zinc,selenium, manganese and cobalt into the green Eu-

c

C>

:c

15

C>

oS
~

S

10

-

-G- Znit- 0 - Se

II.

---..-

0

0

E
8L.

6

8

.s

~

S

4

c

~

II.

2

0
0

10

20

30

40

50

TIME (HOURS)

10

20

30

40

Mn

Co

so

TIME (HOURS)

Fig. 1. Percentage incorporation of Zn, Se, Mn and Co ingreen Euglena at different time intervals.
138

8
c
.2

The excretion rates of zinc, selenium, manganese,and cobalt were similar with each other in the green
cells. They were mostly retained in the cells for longer
than 50 hrs. On the other hand, manganese in theyellow cells was excreted rapidly in spite that the otherthree elements were retained as the case of green cells.
Their chemical forms in the cells are interesting to beelucidated.

20

e.

10

Fig. 2. Percentage incorporation of Zn, Se, Mn and Co inyellow Euglena at different time intervals.

25

E

glena is shown as a function of time in Fig. 1. It isnoticeable that the incorporation rate was remarkable
during the first few hrs , and then slowed down. Similar
phenomena were observed in the case of the arsenate
incorporation into marine diatoms,2) and interpreted
that arsenate was metabolized to organic forms into
the cells.
In the yellow Euglena, on the other hand, the incorporation rates were different from those in green cells
Fig. 2. After the initial rapid incorporation, zinc kept
a plateau until 25 hrs, although the other three elements increased a very little till 25 hrs. The different
pattern of Fig. 2 increased a little till 25 hrs may suggest a unique different behavior of these four elementsin the incorporation mechanism or in the metabolism
into the cells. The rapid decrease of the incorporation
after 25 hrs may suggest a change in the physiologicalconditions of the Euglena cells.

References
1) L. E. Koren and S. H. Hutner: J. Protozool. 14, suppl.,
17 (1967) .

2) M. Katayama, Y. Sugawa-Katayama, and A. A. Benson:
Appl. Organomet. Chern. 4, 213 (1990).

RIKEN Accel. Prog. Rep. 31 (1998), Possibility of the Existence of a Special Substance Involvedin the Uptake of REE by Dryoptreris erythrosora
T. Ozaki, S. Enomoto, Y. Minai, S. Ambe, F. Ambe, and Y. Makide*

Dryopteris erythrosora (a fern) is known to accumulate the rare earth elements (REEs) under natural
conditions. 1) Considering the difficulty in the uptakeof REEs because of the strong tendency of REEs tohydrolyze under the natural conditions, some special
mechanism to absorb REEs is expected to exist in thefern species. In present paper, we report a possibilityof the existence of an unknown substance which might
be involved in the uptake of REEs by Dryopteris erythrosora.
Dryopteris erythrosora was grown in distilled waterfor collection of an unknown substance, which is expected to be released from the roots. After filtered bya glass filter, followed by a membrane filter (pore size,
0.20 p,m), the solution was concentrated at 70°C witha small amount of thymol which was added for the
purpose of sterilization of the solution. The concentrated solution was applied to cation exchange column
to remove the inorganic ions chelated to the substance.
Plates of Au and Ag (300 p,m x 23 mm¢) were irradiated with a 135 MeV/nucleon 12C ion beam accelerated by the RIKEN Ring Cyclotron. The Au target was dissolved in aqua regia, and the solution was
evaporated to dryness. After the residue was dissolvedin 3.0 mol dm- 3 HCI, a multitracer solution was obtained by removing the Au by extraction with ethyl acetate. On the other hand, the Ag target was dissolved
in HN0 3 and then the Ag was precipitated with HCI as
Agel, leaving another multi tracer solution. Mixing thetwo solutions produced the final multitracer solution
used in this study, which contained the radionuclides
of Be, Na, Mn, Co, Zn, Y, Rb, Sr, Ce, Gd, Yb, and
Lu. The solution was evaporated to dryness, and dissolved in ultrapurified water for the experiments. Additional details on the procedures have been reported
previously.2-4)
In Figs. 1 and 2 were shown the uptakes of Gd and
Na into the samples A: without and B: with root washing solution in the uptake solution. Each datum pointin the figures was given as the mean ± standard deviation of five replications. The uptake rates of theelements into mesophylls were represented as follows;
Uptake rate of an element i= (i in a mesophyll / i added to the uptake solution)/ (Rb in a mesophyll) / (Rb added to the uptake solution)
The uptake of Rb was applied to normalization forthe purpose of estimating the individual variation of
the samples as proper as possible, because the flow of

Rb is closest to that of water among the multitracer
elements and as ascent of each element is highly dependent on that of water. 5) As seen in Figs. 1 and 2,
the uptake of Gd was enhanced, while no enhancement
was observed in the uptake of Na. From this, it is suggested that the root washing solution contained some
unknown substance involved in the uptake of REEs.

:ca:: 4.
::::::..

-"C
<.!}

0

Q)

ca
....

Q)

-

~

3.0
2.0
1.0

ca

c..
:::> 0.0
A

B

Fig. 1. Uptake rate of Cd, A: without and B: with root
washing solution in the uptake solution.

::Co

a::
ca 0.3::::::..

z

'0

g-Q)

ca
....

Q)

~

0.2
0.1

ca

0.0

A

B

Fig. 2. Uptake rate of Na, A: without and B: with root
washing solution in the uptake solution.

References
1) T. Ozaki, S. Enomoto, Y. Minai, S. Ambe, F. Ambe,and T. Tominaga: J. Radioanl. Chern. 217, 117 (1997).
2) S. Ambe, S. W. Chen, Y. Ohkubo, Y. Kobayashi, M.
Iwamoto, M. Yanokura, and F. Ambe: Chern. Lett.
1991, 149.
3) S. Ambe, S. Y. Chen, Y. Ohkubo, Y. Kobayashi, H.
Maeda, and M. Yanokura: J. Radioanal. Nucl. Chern.
Articles 195, 305 (1995).
4) F. Ambe ed.: RlKEN Rev. No. 13 (1996).
5) J. J. M. Hooymans: Planta (Berlin) 88,369 (1969).

Radioisotope Centor, Tokyo University

139

RIKEN Accel. Prog. Rep. 31 (1998)

Study on the Uptake Rate of Various Elements into Dryopteris
erythrosora by Multitracer TechniqueT. Ozaki, S. Enomoto, Y. Minai, S. Ambe, F. Ambe, and Y. Makide*
Plants absorb elements in soil via the groundwater,and not directly from the surface of soil particles. Rare
earth elements (REEs) have a great tendency to hydrolyze under the natural conditions, leading to their
low availability to plants. Although REEs are dissolved into interstitial water, those elements are reported to stop at the surface of roots and hardly get
into the upper parts.1,2) However, there are some plant
species, such as Dryopteris erythrosora, which accumulate REEs to a high concentration. Therefore, it isexpected that those species absorb REEs aggressively
from the environment for some use in specific ways of
their own.
Multitracer technique was recently developed at
the Institute of Physical and Chemical Research(RIKEN).3) A multitracer solution contains manykinds of radioactive nuclides produced by high-energy
heavy-ion irradiation of a metal target. Utilization of amultitracer solution makes it possible to efficiently acquire information on the behavior of various elements(nuclides) in the same plant. This is a great advantage, especially for the biological samples which arealways accompanied with a problem arising from individual differences. We have carried out radioactive
tracer experiments to examine the uptake rates of various elements using the multitracer technique.
Fern samples (Dryopteris erythrosora) were approximately 7 cm in length at the beginning of feeding ofradioactive tracers. Uptake of each element was timedependently examined; 7, 14, and 21 days after the
addition of tracers. Each time, the mesophylls were
sampled, and the radioactivity was measured with a
HPGe detector. The uptake rate of an element j intoa mesophyll was represented as follows:
Uptake rate of an element j= (j in a mesophylljj added to the medium)j(Rb in amesophylljRb added to the medium) x 100.
The uptake of Rb was used for normalization for the
purpose of lowering the influence of the indivisual variation, because the flow of Rb is closest to that of wateramong the multitracer elements and because the ascentof elements is highly dependent on that of water. 4 )Uptake experiments by the multitracer technique enabled us to acquire a set of data concerning 16 elements: namely Be, Mn, Co, Zn, Se, Rb, Sr, Y, Zr, Te,
Ba, Ce, Eu, Gd, Vb, and Re (Figs. l(a)- (d)). The
absorptions of Zn and Mn, which are essential to thegrowth of plants, occurred remarkably different comparing with other elements (Fig. l(a)). The absorptionof Mn on the 14th day exceeded 100%, which means
Radioisotope Centor, Tokyo University

140

Mn
~~ 4
300 0 0 0
B 200

(a) ~

i
::>

(b)

(~

'OO

0

o

10

20

Days

125

@100

0--0----0 Rb

~ 75
B
~

50

Re

~ 25

a
::> 0

30

(d)

Se, Te, Zr

o

10

20

30

Days

~100~Ba

~ 75

~

~50

~sr

~ 25

a

::> 0
10

20

Days

30

Be

o

10

20

Days

30

Fig. 1. (a) Uptake rates of Mn, Co, and Zn. (b) Uptake
rates of Rb, Re, Se, Te, and Zr. (c) Uptake rates of
REEs. (d) Uptake rates of Ba, Sr, and Be.

that some portion of Rb had diffused into the agar, andnot that the need of Mn became greater than that of
Rb by the day. No or almost no uptake was observedfor Be, Zr, Te and Se, non of which elements have been
demonstrated to bear any essentiality for plants (Fig.
l(b)). Rare earth elements were absorbed to a higher
degree in comparison with those non-essential nutrient
elements, and the percentage was almost equivalent tothose of Sr and Ba, both of which are considered to
be able to perform the same function of Ca to a certain extent (Figs. l(c) and l(d)). As stated already,the affinity of REEs for agar is strong, and therefore
their availability to plants is much less than Sr and
Ba. The smooth uptake suggests that the fern species
absorbed REEs aggressively for some use to help themgrow and, that some special mechanism was involvedin the uptake of REEs. Further, an ionic radius dependency was observed in the uptake rate of REEs;
largest one (Ce) was absorbed most and the uptake
rates were decreased with the decrease in ionic radius.
This is mostly because the affinity of Ce for agar isweakest among them: i.e., Ce is easiest to be released
from the agar and absorbed.
References
1) S. Ambe, Y. Ohkubo, Y. Kobayashi, M. Iwamoto, H.
Maeda, and M. Yanokura: J. Radioanal. Chern. 195,
305 (1995),
2) A. Wyttenbach, P. Schleppi, J. Bucher, V. Furrer, andL. Tobler: BioI. Trace Element Res. 41, 13 (1994).
3) S. Ambe, S. Y. Chen, Y. Ohkubo, Y. Kobayashi, M.
Iwamoto, and F. Ambe: Chern. Lett. 1991, 149.
4) J. J. M. Hooymans: Planta (Berlin) 88, 369 (1969).

RIKEN Accel. Prog. Rep. 31 (1998)

Multitracer Study on Biosorption of Various Trace Elements
in Yeast Saccharomyces cerevisiae
Y. Nose, S. Enomoto, S. Ambe, and F. Ambe
Recently, metal uptake by microorganisms has been
attracting many investigators' attention, because of its
potential application for removal of toxic radionuclides
and of heavy metals from the environment. Yeast is
known to take up and/or adsorb several metals I } andis thought to be appropriate for research on the mechanisms of biosorption of metals. In the present study,
the uptake of 16 elements (Be, Na, V, Cr, Mn, Fe,
Co, Zn, As, Se, Rb, Sr, Y, Zr, Ru and Rh) by the
yeast Saccharomyces cerevisiae was investigated using
a multitracer technique. This technique enables us to
examine the uptake of various elements under an identical condition.
A multitracer solution was prepared from a silver
target which was irradiated with a 135 MeV/nucleon
I4N beam accelerated by RIKEN Ring Cyclotron. Additional details on the procedures have been previously
reported. 2 ) After the evaporation of the multitracer
solution, ultrapurified water was added on it and thesolution was administered to yeast.
The yeast S. cerevisiae (JCM No. 7255) was purchased from the Japan Collection of Microorganisms,
RIKEN. Cultures were grown in the Difco Yeast Nitrogen Base (Difco) with 0.5% (w/v) glucose (growth
medium) at 25°C in a shaker. Cell growth was monitored by measuring the absorbance at 660 nm (OD660).
Each five milliliter (5 ml) of cultures of OD 660 = 1.0
was taken into a tube and centrifuged at 700 x 9
for 10 min at 25°C to obtain a yeast cell pellet.
The yeast cell pellets were suspended in a 5 mM 2(N-morpholino)ethanesulfonic acid (MES)-NaOH (pH5.4) uptake medium, and centrifuged at 700 x 9 for 10
min at 25°C for 3 times to wash the cells. The washedcells were re-suspended in 5 ml of the uptake medium,and incubated for 30 min at 25 0 C in a shaker. An
aliquot of multitracer solution was added to the yeast
suspension, which was then incubated for 30 min at 25°C in a shaker. After the incubation, the samples were
washed for 3 times with the cold uptake medium, andfiltered by suction through a cellulose acetate membrane filter (Advantec, 0.8 p,m). The filters were allowed to air dry and then subjected to ,-ray mea-

surement with high-purity Ge detectors.
Figure 1 shows the uptakes of 16 elements by the
yeast. The uptakes of Be, Cr, Co and Zn were very
high, approximately 100%. The high uptake of Be isinteresting, because Be is thought not to be essential
and has toxicity for living organisms; in contrast, Cr,
Co and Zn are essential. In the case of V, Mn, Fe,
As, Se, Sr, Y, Zr, Ru and Rh, the uptakes were from
20 to 60%. The uptakes of Na and Rb were below detectable level. The very low uptake of N a was reported
in the literature. I} There are no or few report on thebiosorption of Be, V, Rb, Y, Zr, Ru and Rh by the
yeast. Therefore, this report must be a base of further
investigations.

Be
Na
V
Cr
Mn
.;l:e ~ i,
Fe
Co
Q,I
Zn
Q,I
As
~
Se ~
Rb
Sr
y

I2t1

=
e

~

~

Zr
Ru
Rh

:'l----l

o

20

40

60

80

100

Uptake (%)

Fig. 1.

Uptakes of various elements in the yeast
from a 5 mM 2-{N-morpholino)ethanesulfonic acid-NaOH (pH 5.4) uptake medium
containing the multitracer. Each data represents theaverage of five trials ± standard deviation.
S.

cerevisiae

References
1) K. J. Blackwell et al.: Appl. Microbiol. Biotechnol. 43,
579 (1995).
2) S. Ambe et al.: Anal. Sci. 1, Suppl., 317 (1991).

141

RIKEN Accel. Prog. Rep. 31 (1998)

Heavy-Ion Induced Fission in the Medium Energy Region
H. Araki, J. Sanada, S. Morimoto, A. Yokoyama, T. Saito,
H. Baba, Y. Ohkubo, and Y. Kobayashi
The heavy-ion induced reaction is characterized by
the angular momentum brought in by projectiles. As
for the fission mechanism, the larger the momentum,
the smaller the fission barrier, and eventually the fission barrier vanishes at a critical angular momentum(Lcr). The fission with no barrier is referred to as fast
fission (FaF). In order to investigate a change in thefission phenomena affected by the onset of FaF, weobserved the difference in the mass distributions when
the incident energy (Ei) is below and above the criticalenergy corresponding to L cr .
We bombarded a gold target (5.70 mg/cm 2 thick)with 16 0 ions at a so-called falling ball system installed in the E3B course at RIKEN Ring Cyclotron.
The critical energy for the fast fission is calculated
to be about 140 MeV under the rotating finite range
model. 1 ) The incident energies were adjusted by using
an aluminum foil of appropriate thickness as degrader.
The irradiated samples were analyzed by means of nondestructive "'(-ray spectrometry with Ge detectors.
Mass distributions were deduced from the obtained
formation cross sections on assuming the two assumptions that, in the fission dominant region, the widthof charge distribution is constant, and that the mostprobable charge linearly depends on the mass number A. The resulting mass distribution for the case
Ei = 156 MeV and 127 MeV are shown in the centerand top panels of Fig. 1, respectively.
The fusion fission mass distribution at Ei = 156
Me V should be well approximated by the mass distribution at Ei = 127 MeV under the assumptions that
the FaF does not exist below the critical energy or
below the fission excitation energy.2) Then, the fusionfission cross sections (dashed curve in Fig. 1) were deduced on the basis of the distribution obtained at 127
Me V but by evaluating the peak position from emission of pre-fission neutron and by adjusting the peakheight. They were then subtracted from the total fission cross sections. The resulting residues are plottedin the lowest panel of Fig. l.
Since the barrier of the incomplete fusion fission(ICF) is expected to be higher 3) than the complete

142

10 2
10 1

::0

5

"Q) 10

.'.-.

!II .

1

~

10° .
40

•
.....

20

•

-20

60

140

80

A

Fig.

1.

The mass distributions for the reactions ofwith 16 0 ions at (a) 127 MeV, (b) 156 MeV.
The solid curve is a Gaussian fitted to the experimental data, while the dashed curve in (b) represents thecorrected fusion-fission mass distribution based on themass distribution at 127 MeV. (c) Residual values of
the 156-MeV mass distribution after subtraction of thefusion-fission mass distribution.
197 Aufusion excitation energy, the contribution of ICF is
negligibly small. Therefore, the presently observed
residues in Fig. 1 should be due to the FaF as in thecase of Ref. 2. However, present results are only preliminary. We expect that a more clear-cut feature offast fission may be observed by the future experiment
to be performed at the higher incident energies.
References
1) J. Sierk: Phys. Rev. C 33 , 2039 (1986).
2) H. Baba et al.: Abstracts of Asia-Pacific Symp. on Radiochemistry '97, Kumamoto, A06 (1997); H. Baba etal.: KEK-Proc.-lO, Workshop on Sci. with Short-lived
Nuclear Beams, in press (1997).
3) H. Cohen and W. J. Swiatecki: Ann. Phys. (N.Y), 22,406 (1963).

RIKEN Accel. Prog. Rep. 31 (1998)

Developement of High Intensity Polarized
Slow Positron Beam Using 18F
Y. Itoh, T. Nozaki, N. Nakanishi, A. Goto, Y. Ito, and H. Yoshida*[Positron source, Polarized slow positron beam, 18F, Liquid target]
Short-lived positron emitters produced in liquid targets by bombardment with ion beams from a cyclotron
have proven to be useful for the generation of polarized slow positron beams. We tested various solid andgas targets, BN, C, AI, Si0 2, Ni, Cu, N2 etc., as already reported. 1-3 ) We have tried the utilization of 18F
produced in 180-enriched water by the 180(p, n) 18 F
reaction. Of all the nuclear reactions induced by asmall accelerator, the 18 0(p, n) 18 F reaction gives thehighest thick-target saturation activity. The chemical
property and 110 min half-life of 18F are also suitable for the off-line source preparation and utilization. The positron emitters were transported to thesite of positron moderator, collected on a small spot,
and placed close to a tungsten moderator foil. Figure 1 shows the 18F collection assembly. Two methods, adsorption and evaporation, have been tried forthe collection and fixation of the 18F from the 18 0_
water, which should be recovered.

Proton beam
Slow positronbeam~- ft,'"

1
[Al

vap.'

HeaterS[Bl

Fig. 1. Automated apparatus for preparing the 18F source.

As for the adsorption method, various adsorbent
substances were tested for the 18F. The assembly consists of a turn table, T, source holder, S, and targetwater receiver, R. The source holder can be moved up
and down, and rotated at the down position. At theup position, it is either in water-tight contact with thereceiver or placed very close to the moderator. The
bombarded target water is once transferred into thereceiver (R) by a nitrogen gas pressure. As the adsorbent material, a strongly basic anion exchange resin(100-200 mesh, OH-form) was found to be suitable.
The target water in the receiver is passed slowly
through the resin bed with the aid of a peristaltic
pump. In this method some thickness of the exchange
resin was necessary to collect 18F efficiently by a onethrough treatment. Since this causes low slow positronyield by self-absorption of the emitted positrons, themethod has to be improved so that 18F is collectedusing a thin resin layer.
As for the evaporation method, a minute amount of
K 2C0 3 (0.1 mg) is first placed on the holder (S), andthe target water is transferred on it and evaporated byheating from outside. The water vapor is carried by anitrogen stream to be condensed and recovered, leaving
the 18F on a small area (usually 3 to 4 mm diameter).
It takes about 10 min for the collection and fixationof 18F. The evaporation method for 18F is thought tobe superior to the other methods, giving 106 S-l slow
positrons. The use of gas and liquid targets possesses
the following advantages over the on-site use of solid
targets as a positron source: (1) the positron source
can be placed in an ideal position close to the moderator foil; (2) long transport of slow positron beam
is not necessary; (3) the source intensity can be monitored continuously, easily, and reliably; (4) the moderator is free from other radiations emitted from thetarget under bombardment; (5) a part of the productradionuclide can be used simultaneously for other purposes.
The polarized slow positrons are transferred to thedetector guided with the magnetic field of the solenoid
coils, the helmholtz coils and a deflector coil. Polarization of slow positron beam is measured by using magnetic quenching of positronium (Ps) due to Zeeman
effect. High intensity polarized slow positron beam isused to derive information about the polarization of
the new materials in which they annihilate.
References
1) Y. Itoh et al.: Appl. Sur. Sci. 85, 165 (1995) (SLOPOS-

6).
2) Y. Itoh et al.: Appl. Sur. Sci. 116, 68 (1997) (SLOPOS7).
3) Y. Itoh et al.: Proc. Riken Symposium, "Basics and Application of Spin Polarized Positron Beam" , p. 1 (1995).

Research and Development Dept., The Japan Steel Works
Ltd.

143

4. Radiation Chemistry and Radiation Biology

RIKEN Accel. Prog. Rep. 31 (1998)

Screening of Plants for Soil-Radionuclide Accumulators t
S. Gouthu, T. Arie, S. Ambe, and 1. Yamaguchi
In case of radioactive fallout, persistence of long
lived nuclides in soil and their subsequent transfer into
food chain over a long period through plants is the key
factor. The possibility of "phytoremediation" is suggested to reduce the radionuclides in soil. In order toexploit the natural potential of some plants in absorbing or accumulating certain radionuclides and thus indepleting the soil radioactivity, thirty-two plant species
representing different vegetation types were tested

under laboratory conditions for their comparative ability in taking up radioactive Rb, Co, Sr and Cs. Each
plant was supplied with an equal amount of "multitracer and cesium mixture" solution, and was grown
for a period of 30 days before harvesting for measurements of the activity by Ge-detectors. Values of uptake
percentage of 58CO, 83Rb, 858r, and 137CS by 32 tested
plant species in one month period are shown in Table 1.
As for the potential in absorbing the nuclides from

Table 1. Accumulation rates of 60Co, 83Rb, 85Sr, and 137CS in different plant species.
Uptake rate (i n %Iplant dl)' weight )"Plant species

Common name

Brassica camptslris L. (rapifera group)
B. campwris L. (rapifera group)
B. campeslris L, (pekinensis group)
B. campeslris L. (Japonica group)
B. oleracea L. (ltalica group)
GlyciM max Merr.
Vigna radiala R, Wilez,
Pisum SOliyum L.
Bela Yulgaris L. (cicla group)
SatsoUJ komaroyii IIj in
Amaranlhus mangoS/anus L,
Apium 8rav~oLtns LDaucus carofa L.
Lycopersicon esculentum MilLSOUJnum melongena L.
Cucumis sarivUJ L.
Abelmoschus tsculentlLr Moench.
Eschscholzia cali/arnica Cham,
Papavu nutiicQuie L.
Heleanthus annuw L.

Malricariasp.
CampanuUJ medium L,
Anlirrhinum majus L.
Dklnlhus caryophyl/us L.
lpam«a balaras Poir,
Pharbilis nil Choisy
Zea mays L.
Triticum vulgare L cv. chiholcu
Oriza sativa L cv. koshikahari

Pinnacle sp,
Poa pralensis L.
Allium ruberosurn Rottler

Turni p (Hinona)
Tu rnip (Komatsuna)
Chi nese cabbage
Tumnip (Kyona)
Broccoli
SoybeanMung bean
Pea
Chard
Okahijiki
Edible Amaranthus
Celel)'
CarrotTomatoEggplant
Cucumber
Okra
California poppy
Iceland poppy
Sun flower

Matricaria
Canterberry bells
Snapdragon

Carnation
Sweet potato
Japanese morning glol)'
Maize
Wheat
Rice
Pinnacle grass
Kentucky bluegrass
Chinese chive

Plantdl)' wt ,(ingm)

60Co

83 Rb

85S r

137Cs

0.98 1
1.393
1.465
1.462
1.218
3.383
1.775
1.774
1.555
0.932
0,278
0,362
0,368
2,325
0,554
1.637
0,614
0163
0,138
1.696
0,084
0.527
0,097
0,114
0,039
0,168
1.996
0,378
0,236
0,057
0,115
0,153

037 ±0.17
0,36 ±0,08
0.41 ±0,09
0,25 ±0,03
1.22±0,1I
0,02±0,03
0,06±0,01
0,20±0,18
0. 12±0.IO
0,20±0,17
0.22±0,02
0.01 ± 0 ,01
0.Q3 ±O,OO
1.02±0,01
0.51 ±0,22
0. 17 ± O,OJ
0.09±0,03
0.27 ± 0,07
0. 15±0,06
0.28 ±0.07
0.06±0.06
0,19±0,03
0.01 ±O.OO
O.IS ±0.06
om ±O,OO
0 ,11 ±0,02
0,10 ±0,0l
O,OO±O,OO
0 ,03 ±O,OO
0,03 ±O,OO
O,OBO,OI
0,00 ± 0,00

8,50± 1.08
13,93± 0.45
13,77± 1.48
9.78 ± 1.73
9,14 ± 1.53
6,13± 1.27
6,04± 1.84
9,67 ± 1,27
17,82±3.1 7
11,80 ± 3.72
2,S6±0.39
2.54± 0 ,64
3,39±0,36
25,60± 0,08
6,57 ± 1.71
14.19 ±2.12
2,14±0,42
3.S9± 2,79
2,17±0,31
17.21 ±4.19
1.36± 1.12
6.51 ±2.33
0,S7±0,12
1.58 ±0,20
0,30 ±0,021.27 ± 1.20
13,97 ±6.23
4,90± 4.52
1.75±0.1 8
0.41 ± 0.03
0 ,78 ±0.04
1.2S ±0.40

0.63± 0,18
0.79± 0,06
0.78± 0.04
0.98 ± 0,15
0.65 ± 0, 19
0,50±0,07
0.27±0,23
0.77 ±0,09
0.40±0.68
0. 18±0,310.27 ±0,020.27 ±0,09
0.43±0,06
0.8 1 ±0,01
0.6 1 ±0,25
2.12±0.33
0.74±0,13
0.23 ±0.06
0.10±0,0l
1.36 ± 0.25
0.07 ±0.07
0.55±0.1l
O.OS ±O.OO
0.17±0.02
0.02 ± 0.00
0,20 ± 0.10
0,24±0.1O
0,22±0,20
0,09 ±0,01
0,03 ±O,OO
O,IO ± 0,01
0 ,07 ±0,020.18 ±0,180.29 ±0,03
0.09 ±0,07
0. 16±0,06
0.06±0,01
0.I7±0,04
0.08±0.02
O.5I±O,IO
1.36 ±0,27
0,13 ±0,09
0,08±0,01
0,02 ±0,01
0.08±0,02
1.42 ±0,27
0,07 ±0.03
1.09 ±0,29
0,07 ±0,01
0,04 ±0,01
0,03 ±o.oo
0,36 ±0.27
0.02 ±0.01
O,OS ±0.0l
0.01 ±O.OO
0,03 ±O.OO
0,01 ±O.OO
0,03 ±0.02
0,38±0.14
0.13 ± 0.11
0.02±0.0l
0.01 ±O,OO
0.01 ±O,OO
0,01 ±O,OO

a -The values indicate % uptake from the total supplied amount of nuclides and are the means of three

replicates along with standard deviation .

soil, the ornamental plants like California poppy, Iceland poppy, carnation, Japanese morning glory, andmatricaria showed high uptake rates per gram. 1) Admitting that ornamental plants seemed to be better
accumulators of the soil nuclides, they can not accountfor depleting soil radiation burden to any considerable
level owing to their slow growth and little biomass. So,
keeping in mind the importance of biomass and growing speed of the plants in phytoremediation, we considered the whole plant uptake values. From the resultsin Table 1, most crop plants like Brassica spp., tomato,and cucumber registered considerable uptake rates perplant because of more dry-weight per plant, thoughhaving less accumulating ability per gram comparedwith the plants like poppy, matricaria, and morning
glory (data not shown). It is evident, from the comparison of per gram and total plant uptake values, that
Condensed from the article in J. Radioanal. Chern. 222,247(1997).

the criteria for selection of plants should be not only
the high uptake capability (per gram activity) of theplant species but the other factors like biomass, growing speed, and foliage spread should be taken into account.
In the present investigation we found some accumulator plants such as tomato, chard, and sunflower for
Rb; broccoli and tomato for Co; cucumber, sunflower,
turnip (Kyona), and tomato for Sri and tomato, chard,and cucumber for Cs. This type of screening and selection of accumulators, followed by study of soil andother biological factors around rhizosphere will help in
decreasing the soil nuclides and avoid them, to someextent, becoming equilibrated in the soil components.
References
1) S. Gouthu et al.: J . Radioanal. Nucl. Chern. Lett. 222,
247 (1997).

145

RIKEN Accel. Prog. Rep. 31 (1998)

Possible Role of Soil-Microbes in Plant Uptake of Radionuclides
S. Gouthu, T. Arie, S. Ambe, and 1. Yamaguchi
Root surface of plants supports active bacterial andfungal lives forming a symbiotic system in which themicrobial symbiont is often known to enhance the plantcapabilities in absorbing the soil mineral elements. In
light of this, in phytoremediation of soils contaminatedwith radionuclides the use of specific combination ofplant and microbe can maximize plant's uptake and accumulation. Towards this purpose, tomato and cucumber plants selected through screening for their ability
to absorb soil radionuclidesl} are tested for their uptake in association of some soil-microorganisms, known
to be associated with these plant species. Fungal isolates of Fusarium oxysporum ·f.sp. lycopersici race 2880621a-1 (Foly); F. oxysporum F-4 (NPF); F. oxysporum f.sp. cucumerinum Rfc1 (Focu); and also Agrobacterium rhizogenes SUPP 709 (Agr); were cultured on aliquid broth medium. Tomato (cv. Momotaro) and cucumber (cv. Suyo) plants were maintained in the green
house conditions, and after 15 days of growth the Foly,
NPF, and Agr were inoculated to tomato plants andthe Focu and Agr were inoculated to cucumber plants
by pouring liquid inocula. Multitracer containing theradionuclide elements of Mn, Co, Zn, Rb, Sr, and 137 Cs
was supplied to the inoculated plants. The plants weregrown for 30 days before harvesting for uptake measurements with Ge-detectors.
Figure 1 shows the uptake percentage of nuclides pergram dry weight of tomato plants and Fig. 2 that of cucumber plants. Inoculation of Agr was expected to increase the root growth by inducing adventitious roots,
and thereby cause increased uptake. However, the production of adventitious root did not occur within theexperimental period (data not shown). Tomato plants
inoculated with Foly showed increased uptake of all the
nuclides compared to the control plants. NPF inoculated tomato did not show any uptake difference. During the infection, Foly grows in to the tomato plants
and establishes in the xylem vessels,2) whereas NPF
only grows superficially on the root system. The degreeof contact between the host root and the fungal species
might be a reasons for this difference in uptakes. In
the case of cucumber also the uptake of nuclides wasmore compared to control, but the increase in uptake
was less pronounced. Increased accumulation of radionuclides from soil by plants inoculated with a specific mycorrhizal fungus was reported by Entry et al.
(1994).3) However, the actual mechanism that was involved in the increased uptake of fungal infected plants
remains to be investigated. The present result is an indication of the microbial-promoted plant uptake. Now
we are trying to identify some non-pathogenic rizosphere microbes that can be used for bioremediation
with tomato and cucumber plants.
146

10
•

Control

Agro• NPF!2iI Foly

Mn

Co

Zn

Sr

Rb

Cs

NuclideFig.!. Uptake of tomato inoculated with Agr, NPF, and
Foly.

•

ControlEl

Fcu

III Agr

Mn

Co

Zn

Rb

Sr

C,

NuclideFig. 2.
Fcu.

Uptake of cucumber inoculated with Agr, andReferences
1) S. Gouthu et al.: J. Radioanal. Nucl. Chern. Lett. 222,
247 (1997).
2) T. Arie et al.: Ann. Phytopathol. Soc. Jpn. 61, 311(1995) .
3) J. A. Entry: Environ. Poll. 86, 201 (1994).

RIKEN Accel. Prog. Rep. 31 (1998)

Effects of Heavy Ions on Survival of Arabidopsis thaliana
N. Shikazono, A. Tanaka, H. Watanabe,* S. Tano,* N. Fukunishi, and S. Kitayama
The biological effects of charged heavy particles,
such as the relative biological effectiveness (RBE) on
lethality as a function of linear energy transfer (LET),
have been extensively studied in the bacteria, yeast
and mammalian cells. In these unicellular systems, it
was observed that RBE peaks on reproductive death
were at around 100 keY / /-lm.I)
The effects of heavy ions on multicellular organisms
are not yet fully understood. Ambidopsis thaliana (L.)
Heynh. is a particularly suitable multicellular organism
for studying the effects of heavy ions and of other kindsof radiation because its seeds and plants are small, it
produces a large number of seeds, and because its life
cycle is short. 2 ) We have investigated the effects ofheavy ions on the survival of A mbidopsis using various kinds of ions with LETs of 17- 549 ke V I ;.tm, andfound that the highest RBE value can be obtained by
Ar ion irradiation (LET 252 keY l/-lm).3) Using Ne ionsat the RIKEN Ring Cyclotron, we have elucidated thatthe highest RBE appears at the LET of 352 ke V / /-lm.
To further investigate the dependence of RBE on LET
in Arabidopsis, we used Ar ions of various LETs.
For irradiation, a single layer of the dry seeds of A mbidopsis thaliana ecotype Columbia was carefully sandwiched between kapton films (7.5 /-lm thickness). Seeds
were exposed to Ar ions from the RIKEN Ring Cyclotron. The LETs (252, 350, 396, 562, 656 keY I ;.tm)
for Ar ions at RIKEN Ring Cyclotron were varied byplacing absorbers in front of the irradiation site. The
mean LETs were calculated by ELOSS code (modified
OSCAR code). The plants were grown at 23°C undercontinuous light (40 ;.tE/m2 Is). One month after sowing, plants with expanded rosette leaves were scoredas survivors . RBE value was estimated by comparing
D37 for electrons with that for Ar ions.
The survival curves for Ar ions with LET 252, 350,
396,562, and 656 keY I /-lm are shown in Fig. 1. Ar ionswith LET of 396 keY / /-lm had the smallest shoulder.
In Fig. 2, RBEs with Ne and Ar ions are plotted as afunction of LET. RBE value of survival seems to havea peak at LET over 300 ke V I ;.tm.
The difference in the LET for the RBE peak in unicellular systems and in Arabidopsis might be explainedby assuming that the endpoints compared in the twosystems arose from different mechanisms. Recently, it
was reported that the RBE peak on the interphase
death compared to the reproductive death shifts toa higher LET (around 230 ke V / ;.tm) in mammaliancells. 4 ) The interphase death rather than the reproductive death may mainly contribute to the survival of+ LET252
0100

LET350

IJ LET396<>,......,

LET562X LET656

~

ro

10

>
>
....
:::J

V')

o

40

80

120

160

200

Dos e
( G Y )

Fig. 1. Effects of Ar ion beams with different LETs on
survival. +: LET 252 keY / /-tm, 0: LET 350 keY / /-tm,
0: LET 396 keY / /-tm, 0: LET 562 keY / /-tm, X: LET
656 keY //-tm .

UJ

8

o

Ne

0::

6

•

Ar

co

4

100

1000

LET (keV/ Jlm)

Fig. 2. RBE for lethality with Ne and Ar ions as a functionof LET.

Arabidopsis. Alternatively, there is a possibility thatdifferent repair mechanism (s) may be the main causeof the different LETs for the RBE peak in unicellular
systems and in Arabidopsis plants.
Isolation and characterization of radiation sensitive
mutants of Arabidopsis may greatly facilitate the elucidation of underlying mechanisms of the occurence of
RBE peak.

References
1) G. Kraft: Nucl. Sci. Appl. 3, 1 (1987).
2) U. Bork et al.: Adv. Space Res. 9(10), 117 (1989).
3) A. Tanaka et al. : Int. J. Radiat. Biol. 72, 121 (1997).
4) H. Sasaki et al.: Radiat. Res. 148, 449 (1997).

Advanced Science Research Center, JAERI147

RIKEN Aeeei. Prog. Rep. 31 (1998)

Effective Plant-Mutation Method Using Heavy-Ion Beams (II)T. Abe, C.-H. Bae, H. Takahashi, 8. Kumata, and 8. Yoshida
We found that accelerated heavy-ion beams are very
effective tools for the mutagenesis of plants under aparticular condition of the fertilization cycle. In thepresent paper we examine the effect of heavy-ion beams
on various tissues of tobacco, and describe applicability of this new technique for screening the herbicideresistant mutants.
Anthers from the tobacco (Nicotiana tabacum cv.
BY-4 and Xanthi) flower-buds were cultured on socalled Nakata medium containing 2 mglL IAA, 1 mglL
kinetin, 3% sucrose, and 0.6% agar. After 4 to 10 daysof incubation, anthers were irradiated by the heavyion beams (l4N or 20Ne at 135 MeV lu) within a dose
range of 5 to 100 Gy. The LET of the Nand Ne ionswere adjusted to be 28.5 and 63.0 Ke V I p,m, respectively. One month after the irradiation, the numberof the pollen germination was counted. The high-dose
irradiation caused a decrease of the germination whereembryos developed from pollen grains (Fig. 1). Regenerated plants from the pollen grains which are androgenic haploids become homozygous dihaploids in asingle generation, thus this technique can considerably
shorten a breeding cycle and fixation of mutant line.
After 36 to 96 hours of pollination, Nicotiana
tabacum cv. BY-4 intact embryos in the flowers of Nico-

tiana tabacum cv. BY-4 were irradiated by heavy-ion
beams (l4N at 135 MeV lu) for 36 to 96 hrs after pollination. The treated plants were cultivated in a green
house and the resulting Ml seeds were harvested one
month after the treatment. Two-months old Ml plants
with dark green leaves were used in the resistance test
against 8-23142 (N-[4-chloro-2-fluoro-5-propargyloxyphenyl].:3,4,5,6-tetrahydrophthalimide), a herbicide inhibiting Protox which is a key enzyme in the chlorophyll biosynthesis at chloroplasts. Young leaf tissues
were treated with 0.5-1000 p,M 8-23142 at 25°C in
the continuous light (approx. 78 p,mol m- 2s- 1 ). After 2 days, the chlorophyll contents of each tissue were
measured, and one tolerant plant was selected by thisbioassay. Chlorophyll contents were decreased by 50%
at 1.1 p,M of 8-23142 in control (wild type) but at
1.1 mM of that in the tolerant plant (Fig. 2). The results obtained will open a new field of research on themutation spectrum of herbicide targeting sites.

125 "1-0:====::::0-----""1~::;100cc~8;:. 75

-ae

60

~

-

.s
.c 50

50

U

~
~

'"'

40

C
Q

:c
30
~
c

Os

'"'

~

10

1000

20

~

Fig. 2. Effects of 8-23142 on chlorophyll contents of wildtype plant and the tolerant plant. 0; wild-type, and e ;tolerant plant.

10

10

20

30

40

50

60

Dose (gray)Fig. 1. Effects of the anther treatment with ion beams on
the pollen germination. e; N ion for BY-4, 0; Ne ion for
BY-4, A; N ion for Xanthi, and 6; Ne ion for Xanthi.

148

100
Concentration (~M)

References
1) T. Abe et al.:in Modification of gene expression
and non-mendelian inheritance, edited by Oono andTakaiwa (NIAR, Japan, 1995), p. 469.

RIKEN Accel. Prog. Rep. 31 (1998)

Cell Death and Mutation Induction on Cultured Cells by
Irradiation of Heavy Ions and X-rays
T. Kawada,* N. Shigematsu,* H. Ito, S. Yamashita, A. Takeda,* K. Toya,*
R. Ishibashi,* A. Kubo,* T. Kanai, Y. F'urusawa, and F. Yatagai
In order to evaluate the biological effects of heavyion beams and X-rays on cultured cells, we have investigated the cell-killing effects and mutation induction
at the hprt locus. Previously, we reported that 'heavyion beams showed much more powerful cell-killing effects than X-rays and that the higher frequency ofmutation took place with heavy-ion beams comparedwith X-rays. 1) In this report we have used one cell-line,
MDA-MB231 (human breast cancer origin) to evaluate
the biological effects of heavy-ion beams and X-rays
and have studied the biological effect of fractionatedirradiation against V79. The heavy-ion beams we employed were carbon (C) beams and neon (Ne) beams.
Survival curves of MDA-MB231 against the dose ofheavy-ion beams and X-rays were shown in Fig. l(a).
Carbon beams and neon beams had much more powerful cell-killing effects than X-rays. When the carbon
and neon beams were used at the same LET level (80keY / J-lm), carbon beam showed slightly stronger cellkilling effect. Fig. l(b) shows that neon beams have asmaller mutation induction effect than that of carbon
beams when the carbon beams and neon beams were
employed at the same LET level (80 keY / J-lm). Thistendency was similar to V79 and RM G 1. 1)
The effects of fractionated irradiation (3 hr interval) on cell survival and mutation frequency against
V79 were also investigated. Comparison of biologi-

cal effects of V79 cells between single and fractionatedirradiations, employing carbon beams and X-rays, isshown in Fig. 2(a) and Fig. 2(b). Carbon beams had
no significantly different effects on cell-killing between
single and fractionated irradiations, whereas X-rays
had. When the carbon beam irradiation was fractionated, the mutation frequency was reduced although
the survival curve was not affected. When cells were
irradiated by X-rays, the cell survival was increasedby fractionation, but the mutation frequency was notchanged. On the other hand, when cells were irradiated by heavy-ion beams, survival curves were notaffected, but the mutation frequency was reduced.
V79

(a)

rl'ldlOMd.

- --<)-· ·X.,.,...."..

'j"
""~
]

0.1

0.01

0.001

13

(b)

.

~

i

l

"""
.S!

S
~

2000

l'

- - + - X.fty-tinlie,.,~X-ra}'-rractioaation_ . . . _ •. Carboa(80t..)-finale, 1

I~- - . - - Carboa(IIOt..)-rrKliODatioa.

I,.f,,-

1000

/,/
.' 1

~

'I
.. I

.;~--;.

MOA-MB231(a)~c.tIon(lJOt.~)- Ii "",--<>--""-~- - . - - Neon (SOkeV)

o

1

1

3

4

,

6

7

a

9

10

11

12

0-(0,)- - - Carbon(SOkeV)
0.1- - X-ray (150kVp)
0.01

0.001

Fig. 2. Survival curves of V79 against X-rays and carbon
beam by fractionation, (b) Mutation frequencies of theV79 per 106 cells after irradiated by X-rays and carbon
beams by fractionation.

0.000 1
10

0

12

(b)
- - . - - Neon ( SOkeV)

450
~

400

Ii

l

350

""

250

S

150

.... .. ... Carbon(80keV)

300-

X-ray (150kVp).g 200
~

100
50

o

I

2

3

4

,

6

7

8

9

10

Dose(Gy)

Fig. 1. (a) Survival curves of MDA-MB231 against
X-rays and against carbon and neon beams, (b) Mutation frequencies against the X-ray, carbon beam andneon beam irradiation.
Department of Radiology, Keio Univ. School of Medicine

We have evaluated the mutation caused by carbon
beams, neon beams, and X-rays. We conclude as follows. (1) The mutation frequency is higher for thecells which were irradiated with heavy-ion beams thanwith X-rays. (2) The mutation frequency of MDAMB231 is less for the neon than carbon beams. Thistendency is in accord with previous report. (3) When
V79 was irradiated with heavy-ion beams, the fractionated treatment can reduce the mutation frequency
without decreasing the cell-killing effects.
References
1) N. Shigematsu et al: RIKEN Accel. Prog. Rep. 28, 117(1995).
2) K. Toya : Nippon Acta Radiol. 56, 736 (1996).

149

RIKEN Accel. Prog. Rep. 31 (1998)

Cell Cycle Progression after Heavy-Ion Irradiation
K. Eguchi-Kasai, H. Itsukaichi, T. Kanai, and F. Yatagai
We have studied the cell cycle progression in cultured mammalian cells after irradiation with C-ion
beams. Asynchronous V79 cells were irradiated bycarbon ion beam (LET ~ 30 240 keY I /-tm) in monolayer using the cyclotron and RIMAC at NIRS and the
RIKEN Ring Cyclotron. The cell population at G 2 andM (G 2 /M) phase measured by fiowcytometer (FCM)
increased with incubation time after irradiation. Accumulation of cells at G2 /M phase was observed from
4 h after irradiation. Accumulation lasted for several
hours, with a peak at around 6 h. Accumulation length
depended on irradiation dose and LET. The maximum
value and the width of the peak increased with irradiation dose for X-rays. For C ion with LET of 30 and 77
ke V l /-tm, the peak value increased with dose up to 3
Gy. Cells stayed at the G 2 /M phase longer when they
were irradiated by a higher dose or by the radiations
with a higher LET. When cells were irradiated by theiso-survival dose, the profile of the G 2 /M phase cells
was similar each other for X-rays and C-ions with 3
LET values of 30, 77 and 240 keY I /-tm (Fig. 1). However for C ion with LET of 240 ke V I /-tm, the ratio of
G 2 /M to total increased up to 8 h, later than the ion
with lower LET. We have not analyzed longer incubation period for this LET C ion, because irradiation
field at NIRS cyclotron is small and cell growth easily
slow down. Further studies are needed at the higher
LET region than 100 ke V I /-tm. In our first experiment
f'V

150

V79,2 Gy
100

-tf.

80

c:
0

...

60

240 keV/llm~" . ·f~U-...cu 40-,'.;"<.

,.:...

.i~., \ ,"~']r" ,

N

keV/llm'i ,., .

"--'-" ~'"" ,"" 'l

:IE

CJ

n

30 keV/llm "" JjI

20
X·rays

0
0

2

4

6

8

10

12

14

Time after irradiation (h)Fig. 1. Kinetics of the cell fraction at G2/M phase after
C-ion irradiation, Cells are irradiated by X-ray (X) or
C ion. LET of C ion is indicated in figure in ke V / 11m.

of cell cycle analysis at the RIKEN Ring Cyclotron,
little accumulation at G2/M phase were observed for
8 h incubation after the C-ion irradiation with LET of
153 ke V I /-tm. Cells might be synchronized during thetransportation from NIRS to RIKEN, We shall repeat
similar experiments using the samples more carefully
prepared.

RIKEN Accel. Prog. Rep. 31 (1998)

DNA Analysis of HPRT Mutations Induced by
High-LET Carbon- and Neon-ion Beams
Y. Kagawa, T. Shimazu,* N. Fukunishi, A. Fujie, M. Hirano,* F. Hanaoka, and F. Yatagai
Analysis of the nature of mutations induced by highLET heavy ions can contribute not only to basic research into biological effects but also to applications
for radiation therapy and radiation risk estimation.
To obt ain information about the mutations causedby exposure of cells to heavy-ion beams, we lookedat that level of LET at which the particles lose mostof their total energies and stop shortly after passing
the cell. To acheive this exposure, the human lymphoblastoid TK6 cells were irradiated by the beams
adjusted to LET 250, and 310 keY / /-tm for C- andNe-ions, respectively. The hypoxanthine phosphoribosyltransferase (HPRT) mutant clones were selected byresistance to 6-thioguanine (5 /-tg/ ml) . As shown in Table 1, HPRT mutations were clearly induced by irradiation with each heavy-ion. We have analyzed precisely
the obtained mutant clones by multiplex PCR, long
PCR, and DNA sequencing of both genomic DNA andeDNA. The comparison of mutants by multiplex PCR
analysis is shown in Table 2. Approximately 60% of
the C-ion induced HPRT mutant clones showed point
mutations . This result is consistent with our previous analysis of HPRT mutants from human embryo

cells after the exposure to a similar high LET C-ion
irradiation. 1,2) In contrast, about 85% of the mutants
induced by Ne-ions were classified as deletion mutations. These events included unique mutations such as
a complicated loss of multiple exon-regions, mutants
with the presence or absence of the exon 6 region itself, and other unique events (data not shown). The
exon 6 events were seen only after Ne-ion irradiation.
We conclude that these C- and Ne-ion irradiations produce clearly different mutational specificities.
We are also exploring the use of long PCR methodology on genomic DNA to get more detailed information about the deletion mutants. Figure 1 shows somemutants that are grouped together by multiplex PCR
analysis as exon 6 deletions. Clearly, long PCR showseach mutant to be distinct deletions of 3.4, 2.6, and5.4 kb in size.
Mutants

Table 1. The surviving fractions and mutation frequencies.
Heavy Ion
LET (keV / p,m)
Dose (Gy)Surviving fraction
Mutation frequency(X10-6)+-22.1 kb

Ne
C
250
310
3.0
3.0
0
1.0
0.23 0.20
2.7
4.4
0.6

Table 2. Classification of mutational events by Multiplex
PCR.
Ion(LET, keY / p,m)Whole region deletion
Partial region deletion
Point mutation
Total number of mutant clones

C
(250)
1
10
17
28

Ne
(310)
5
24
5
34

+-9.4kb+-6.6kbFig. 1. Analysis by long PCR.

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).

Toray Research Center

151

RIKEN Accel. Prog. Rep. 31 (1998)

A 100 ps Lived New Luminescence Component
in Ion Irradiated Alumina
K. Kimura, W. Hong, J. Kaneko, and N. !toh
Many luminescence studies on pure a-alumina excited by X-ray, electrons, and photons have revealed
two intrinsic luminescence bands at 7.5 eV (163 nm)
and 3.8 eV (326 nm) as Valbis and Itoh had reviewed.
The 7.5-eV band can be assigned to a self-trapped exciton (STE) while the 3.8-eV band may be assigned
preferably to a excited F+ -center, although extra STEmodel cannot be ruled out. l ) Recent studies seem still
not to have obtained the decisive assignment. 2 ,3) We
have studied on luminescence from the ion-irradiatedalkali and alkaline-earth halides, especially on the effect of high-density excitation, using a fast decay measurement technique. 4) The present report summarizes
principally a new finding of a 100 ps decay component
observed on the luminescence decay curves of ion irradiated a-alumina.
Ion irradiation has produced luminescence bands at
280, 422 , 688, and 709 nm in addition to 326 nm but
the decay measurement has showed that those, except for the 326-nm band, are due to the slow growing
components like after glow. Then, they are reported
elsewhere. 5) The decay curve of the 330-nm (3.8 eV)band, known in case of electron irradiation, shows thatafter the rapid rise in the initial stage, there appears aslow growth of 20% of the total near 200 ns and thenthe intensity decays with a half lifetime of about 400
ns. The decay for the ion irradiation was quite different
as Fig. l(a) shows. No after growth can be seen andits half lifetime of about 1 ns is much smaller than thatin the case of the electron irradiation. In addition it
was found that with increasing linear-energy-tran~fer(LET), namely, with increasing excitation density, thedecay is enhanced with intensification of the initial riseof decay curve. The ratio of the rise for Kr ions to thatfor Ar ions is about 16, which is much larger than the
LET ratio of these ions, 1.5. These results suggestthat there is an extremely fast formation process forthis band and that the densely-formed excited statesinteract each other radiatively. Furthermore, the decay was not slowed down with decreasing temperature,
but was enhanced: The initial rise at about 6 K was
decreased at least 50% of that at room temperature forboth ions. The result suggests that the luminescencecannot be assigned to the excited state associated withthe recombination since most of centers are frozen at
this temperature. Thus , the interaction between the
excited states must be the long range or distant interaction. Now, the assignment of the origins of the
3.8 eV luminescence band has been so far separated
into two candidates. One is the STE which belongs
another type STE different from the one due to the
7.5 eV band, the other is due to the excited F+ center
formed by charge recombination. The present results
support the former model since this can form STE invery short time range. Also, the results suggest the
decay enhancement is stimulated by the distant inter152

(a)

Itrll

(b)

-e 500
OJ

~

.D
L.

o~.

(1J

~
0.0

2.0

4.0

TIIIE/n$

6.0

8.0

Fig. 1. (a) LET dependence of the decay curves at
330 nm; the inset shows actual relative intensities.
(b) A time-resolved spectrum obtained by Kr-ion irradiation at 150 K.

action between STE's for case of ion irradiation.
In addition, was found a decay component disappearing in about 100 ps. Figure l(b) shows a timedependent spectrum for case of Kr-ion irradiation at
150 K, where the decay curves due to the 326-nm band
were subtracted since they could be approximated bydouble exponentials except for the initial sharp decaying part; a spike at 300 nm is due to an accidental error. The figure shows that the new band has a peak ataround 400 nm, a broad FWHM of about 2.7 eV, and ahalf lifetime less than 100 ps. Furthermore, their initialrises were intensified by increasing LET. However, notemperature effect was observed. Therefore, the new
band has the characters that (1) its half lifetime ismuch shorter than the spontaneous one of the trapped
exciton, and (2) the decay is enhanced with increasing excitation density even if the centers are frozen.
These characters may suggest a stimulated emissionof the excited states associated with the formation ofloose bond. The free exciton can be ruled out becauseof the lower energy of the luminescence, although thefree exciton must have a very short lifetime. The excited state seems to originate from the STE, but it is
not certain at present.
References
1) J. Valbis and N. Itoh: Radiat. Ef. Defect. Solid. 116,
171 (1991).
2) A. S. Portnyagin, I. I. Milman, and V. S. Kortov: Sov.
Phys. Solid State 33, 1272 (1992).
3) V. Muerk: Materials Sci. Forum, 239/241, 537 (1997).
4) K. Kimura and J. Wada: Phys. Rev. B 48,15535 (1993);
K. Kimura: Nucl. Instrum. Methods Phys. Res. B 90,
100 (1994).
5) K. Kimura, W. Hong, J. Kaneko, and N. Itoh: to be
published on Nuel. Instrum. Methods Phys. Res. B.

RIKEN Accel. Prog. Rep. 31 (1998)

Luminescence Spectra and Decay Curves of
Ion Irradiated Diamonds
J. Kaneko and K. Kimura
Recently, it has become possible to obtain highpurity synthetic diamond crystals. These diamond
crystals are used for development of electrical devices
and radiation detectors. 1) A cathode luminescence is astandard method for characterization of such diamond
crystals, because it is possible to extract some information about band-gap energy, centers of impurities
and vacancies. Such diamond crystals were irradiatedby several kinds of ions at the RIKEN Linear Accelerator. Then the luminescence from diamond crystals wasmeasured during this experiment. Moreover, a decay
curve of free-exciton recombination luminescence wasmeasured by using SISP (Single Ion hitting and Single
Photon counting) system 2) whose time resolution was
better than 100 ps.
Synthetic high purity type IIa single diamond crystals were mainly used in this experiment. Luminescence spectra and decay curves were measured at room
temperature and at 80 K. The band "A" which was reported in previous studies having used electron beams
was dominant in the spectra at room temperature, andit had a very high luminescence efficiency. The wave
length for the center of the band "A" was previously
reported as 427 nm (2.9 eV), but it was 483 nm (2.56
eV) on these synthetic type IIa diamonds. The decay
time of the band "A" region of these diamond crystals
was very slow and had a value of ms order.
Figure 1 shows a luminescence spectrum of synthetic
type IIa diamond bombarded by He+ ions at 80 K.
The intensity of the band "A" decreased one tenth ofthat measured at room temperature. Moreover, thecenter of the band "A" shifted to the lower energy,i.e., 545 nm (2.27 eV). A peak regarded as free-exciton
recombination luminescence was observed at 235 nm(5.27 eV). A free exciton recombination luminescencereft.ects a band gap energy of diamond, it is considered
as an index of diamond crystal perfection. Figure 2
shows a decay curve of luminescence of the free exciton recombination luminescence. It consisted of two

150
~

100

>=

50

o

~~~~~~~~~~~~~

200 300 400 500 600 700 800
Wave length [nm]Fig. 1. Luminescence spectrum of IIa diamond irradiatedby He+ ions at 80 K.

200Type lIa Diamond
Ion: He+
Temperature: 80K
Wave length: 235nm

150
-0
Q)

>=

100
50
5

10

15

20

Time [ns]Fig. 2. Decay curve at 235 nm of IIa diamond irradiatedby He+ ions at 80 K.

components having decay times of 1.3 and 5.4 ns.
References
1) J. Kaneko and M. Katagiri: Nucl. lnstrum. Methods
Phys. Res. A 383, 547 (1996).
2) K. Kimura and J. Wada: Phys. Rev. B 48,15535 (1993).

153

5. Instrumentation

RIKEN Accel. Prog. Rep. 31 (1998)

Computing Environment Surrounding
the Accelerator Research Facility
T. Ichihara, Y. Watanabe, and A. YoshidaIn this report, we describe a brief summary of the recent computing environment surrounding the RIKEN
Accelerator Research Facility (RARF). General description of the data acquisition system at the RARF
can be found elsewhere.!}(1) Off-line data processing system
Figure 1 shows the main part of the computing environment of RARF. Open VMS j AXP clusters of 12
nodes are main components of the current date analysis processors. These nodes are connected by 100 Mbps
FDDI and ethernet. Total 330 GB of hard disks areavailable for the storage of the experimental data.
Recently, the requirement to support the UNIX operating system at RARF has increased, and we havedecided to install and support two UNIX systems at
RARF. In the beginning of 1998, two Alpha CPUs

(Digital UNIX) at 600 MHz and two Ultra Sparc CPUs
at 300 MHz (Solaris 2) have been installed for UNIXuser's environment.
(2) On-line data acquisition system
Currently, seven VAX computers are used for
CAMAC-based on-line experiments at the RARF. Independent measurements and detector tests can be
performed without an interference. Gradual replacement of the data aquisition system from the VAX with
Q22-bus interface (Kinetic 3922) to the Alpha work
station with PCI-bus interface (Kinetc 3915) is now inprogress. 2 )(3) Wide area computer network (WAN) conectivities
The WAN bandwidth between RIKEN and
STAjIMnet internet has increased from 1.5 Mbps to
6.0 Mbps in April 1997. Since we need a much larger
bandwidth (more than 10 Mbps) with BNL in USA for
the RHIC Spin Project, we have submited an application to the APAN (Asia-Pacific Advanced Network)
project. 3 ) The APAN project is expected to start operating in May 1998 and at that time the bandwidthof the APAN supported USA-Japan internet backbone
is expected to become 45 Mbps.
(5) Address of the electronic-mailThe address of the electronic-mail for a general userof the RIKEN Accelerator Research Facility is described as follows, where the userid should be replacedby user's proper name.
(Internet)
userid@rikaxp.riken.go.jp(HEPnet jD ECnet)
rikaxp:: USERID (or 41823::userid)

References
1) T. Ichihara et al.: IEEE. Transaction on Nuclear Science, 35-6, 1628 (1989), see also

Fig. 1. Main part of the computing environment of RARF.

http://www.mrj.riken.go.jp/mrf/exp/comp/2) K. Yoshida et al.: to be published.
3) see for http://www.apan.net/

155

RIKEN Accel. Prog. Rep. 31 (1998)

Optimization of Hexapole Magnet for ECR Ion Source
T. Kurita, T. Nakagawa, and S. M. Lee
Usually the permanent hexapole magnet is used to
impose the radial magnetic field for plasma confinement in ECR ion source. 1) In the present paper, weinvestigate the magnetic field strengths with respect
to the size of parmanet magnet and to the number ofmagnet pieces in order to optimize the strength.
Figure 1 shows the cross sectional view of a typical hexapole magnet which consists of 24 piecesof permanent magnet. As a typical demagnetization cureve B (H) of permanent magnet for calculation of magnet field, we adopted a straight line from
(H=-130000 [A/m], B=O [Gauss]) to (H=O [A/m],
B=130000 [Gauss]) as shown in Fig. 2. The dependence of the magnetic field strength on the size of permanent magnet is shown in Fig. 3. The horizontal axis
is a ratio of the external radius to internal one. The
vertical axis is a magnetic field strength at the half
point of the internal radius. Each line is the case when
number of pieces was 24. The dashed line indicatesthe case when internal radius was 4 cm. The solid line
indicates the case when external radius was 2 cm.
As show in Fig. 3, when magnetic field made by magnets of different size is plotted as a function of the sizeof normalized with internal radius, the magnetic field
does not depend on the internal radius of hexapole

5000~_-t:..I

4500
VI
(J)
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ro 4000

8 3500
"0
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~

u

3000

:;:;
Q.)
c

2500

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ro

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2

1

4

3

5

8

7

6

Extarnal Radius/ Internal RadiusFig. 3. Dependence of the magnetic filed strength on thesize of hexapole magnet.

magnet. The magnetic field strength increase with normalized radius up to rv3.5 and then saturates almost.
Figure 4 shows the magnetic field strength as a function of the number of pieces. In this calculation, weused the one with internal radius of 4 cm and external radius of 9 cm. The magnet field strength at thehalf point of internal radius are plotted. Magnet fieldstrength increases with the number of pieces as shownin Fig. 3. However the saturation appears from 24 or
30 pieces. It seems that a reasonable number of pieces
is 24 or 30.

VI
tJl

3900

ro

3850

:l

C,,!)

t
r:::
e

C>

+-'

36 pieces

30 pieces

16 pieces

Fig. 1. The shape of Hexapole magnet consisting of 24
permanent magnet pieces. Arrows indicate the directions of the magnetization.

_-----0

3800
3750

tJl

-c

Q)

-.::
u

3700

-.::;
aJ
r:::

3650

ro

3600

C>

:::E

15

20

25

30

35

40

Number of Magnet Pieces

Fig. 4. The magnetic filed strength as a function of thenumber of magnet pieces.
-130000

H[A/m)

Fig. 2. Demagnetization cureve B(H) of a typical parmanet magnet.
156

References
1) R. Geller: Ann. Rev. Nucl. Part. Sci. 40, 15 (1990).

RIKEN Accel. Prog. Rep. 31 (1998)

Development of the Slow Highly Charged Ion Beam
below 100 eV /q from an ECR Ion Source
for Ion-Atom Collision Experiments
M. Kitajima, Y. Nakai, Y. Kanai, Y. Yamazaki, Y. Awaya, and Y. Itoh
In order to study the charge transfer processes fromhighly charged ions to atoms and molecules in the collisional energy range of below 100 eV /u, a new experimental setup of producing a mono-energetic slow
highly charged ion beam below 100 eV /q has been developed. The apparatus is set at the 30° beam lineof the RIKEN 14.5 GHz Caprice ECR ion source. 1)
Schematic view of the apparatus is shown in Fig. l.
The apparatus consists of deceleration lens, beam collimator, and beam energy selector. Highly charged ionsare extracted by the beam energy ranging 1-5 keV / q
into the beam line. Since the finial beam energy depends on the potential of the plasma chamber of theion source, the beam line is floating from the ground
potential, so that a sufficient extraction potential canbe applied. The ion beam is decelerated down to thebeam energy of 100 eV / q and focused by the deceleration lens and collimated by the collimator. The beamenergy selector consists of entrance lenses, two sets ofhemispherical electrostatic analyzer, and an exit lens.
Typical currents of the energy selected N S+ beam are
50 pA at the pass energy of 110 eV /q and 10 pA at
the pass energy of 30 eV /q.
In order to obtain the resolving power of each of thehemispherical analyzer, energy broadening (b..E) of ion
beam passed through the first hemispherical analyzer
has been measured by the second hemispherical analyzer. The resolving power has been determined byfitting the data with the next equation.

tlE = 22(ax/2)2 - (ax/2)4(b/2)2 + (ax/2)2Here, a is the resolving power of each hemisphericalanalyzer, b the energy broadning of the ion beam at
the enetrance slit of the first hemisphere, x the passenergy of the hemisphere, and b..E the measured energy broadening of ion beam passed through the firsthemisphere. The results are shown in Fig. 2 as a function of the pass energy. The resolving power of eachhemispherical analyzer has been determined from theabove fitting and found to be 1/90.

•
BeaD energy selector

SecondoDece I era t ion lens; ';:-::;;;~\$$3--------- - ------)
Fig. 1. Schematic view of the apparatus. Ion beam of 1-5
keY /q from the 14.5 GHz Caprice ion source is decelerated down to 10-100 eV /q and selected the energy.

50

100

Pass Energy (eV/q)

Coli iu tor

Fig. 2. The energy broadening ~E of ion beam passed
through the first hemispherical analyzer as a functionof the pass energy. Solid curve shows the results of thefitting with a = 1/90 and b = 1.5.

References
1) Y. Kanai et al.: RIKEN Accel. Prog. Rep. 30, 168(1997).

157

RIKEN Accel. Prog. Rep. 31 (1998)

Precise Determination of Neutron Beam Polarization at 16 MeV
K. Sagara, T. Fujita, K. Shigenaga, H. Akiyoshi, K. Tsuruta, K. Ogata,
T. Yagita, H. Okuda, H. Nakamura, and T. Nakashima·
A 16 MeV n-beam was produced by 2H(d, n)3He reaction at Ed = 13.15 MeV, and the n-beam polarization was determined using the n + 4He scattering. Polarization of the a~beam was measured using 3He(d~ p)reaction. The production development of n-beam has
been made at Kyushu University, and a precise experiment on the analyzing power Ay (B) of n+ d scattering
will be made using a high-intensity d-:'beam available
from RIKEN AVF Cyclotron.
The gas cell for 2H2 target was the same as wasused to produce a 12 MeV n-beam,l) except that the
thickness of Ta window foils for the beam entrance andexit was increased from 3 to 5 /.Lm so as to increase the2H2 gas pressure from 3 to 5 atm. The pressure of the
3He target gas was also raised from 1.5 to 2.5 atm. The
4He target was liquid, and worked also as a scintilator.
First, the analyzing powers Ay (B) and Ayy (B) of
3He(d, p) reaction were measured at Ed = 10-16 MeV,
and the maximum of Ay (B) was determined within an
accuracy of about 0.7%.
Increase of the n-beam energy from 12 MeV to 16
MeV caused two problems. One problem was a large
increase of the n- and [-fluxes which were mainly produced at the window foils and at the beam stopperof Ta, and which hit the neutron counters of NE213
to yield large backgrounds. A shield of 30 cm thicklead attenuated the fluxes by about an order of magnitude. However, an additional lead could not reduce
the flux. By surrounding the flux source with a 10
cm thick paraffin block, the n-flux was decreased byanother order of magnitude. Although the [-flux isstill high, the [-signals can be rejected using the n-[separation circuit.
Another problem was the absolute determination of
the n-beam polarization. From the n+ 4 He experiment,
we have obtained the data for K~(OO)Ay(B). The polarization transfer coefficient K~(OO) of 2H(d, n)3He reaction can be determined with the knowledge of Ay(B).
Since Ay (B) of the n+ 4He scattering takes theoretically maximum value (=1) near 12 MeV, the maximumof Ay (B) at 12 Me V can be well approximated as 1.000.
At 16 MeV, however, the approximation does not hold.
Moreover, the existing several sets of the phase shifts
for the n + 4He scattering predict different Ay (B).
We therefore made a modified phase shift analysis.
An existing set of the phase shifts was adopted as astarting point, and the cross section data were produced from the set. Then, the phase shifts and K~(OO)
were so adjusted as to fit our K~(OO)Ay(B) data andthe cross section data. Figure 1 shows the result. We
Faculty of Science, Kyushu University

158

=:t>
~

0.4

~,.,

0

o

120

60

180

Fig. 1. Measured asymmetries for the ii + 4 He scattering (filled circles) and the result of modified phase shift
analysis curve.

have obtained almost the same values for K~(OO) andphase shifts from any set of the existing phase shifts.
The K~(OO) value obtained at 16 MeV (preliminary)is shown in Fig. 2 together with our data at 12 Me V
and TUNL data. 2 ) A half of the difference between
our data and TUNL data is due to the different Ay (B)values adopted.
The n- beam polarizations P~ is expressed as

P~ = 3/2K~(OO)p~/[1 - 1/4Azz(OO)p~yl.

(1)

Since the analyzing power Azz(OO) of 2H(d~ n)3He reaction was also measured, we can determine P~ fromthe d-:' beam polarization P~ and P~y.

0.7

~,.,
~

0.6

5

,0

'5

20

En(MeV)

Fig. 2. Polarization transfer coefficient, K~(OO), of the2H(ct: ii)3He reaction. Filled and open circles are ourdata and TUNL data,2) respectively.

References
1) K. Sagara et al.: RIKEN Accel. Prog. Rep. 28, 121(1995).
2) P. W. Lisowski et al.: Nucl. Phys. A 242 , 298 (1975).

RIKEN Accel. Prog. Rep. 31 (1998)

Developement and Characterization of
the Self-TOF Neutron Detector
N. Nakao,*l M. Nakao,*2 M. Sasaki,*2 T. Nakamura,*2 T. Shibata,*l and Y. Uwamino
Since the facilities require more massive shields withincrease of the accelerating beam current and energy,
the shielding design at higher accuracy is essential tosave the construction cost. Such shielding designs are
performed according to the results of particle transport
calculation using the variety of simulation codes. Although high neutron energy spectra are neccessary inthe shielding experiment for estimating the accuracy ofsuch simulation codes, such data are very scarce above",100 MeV.
Now, spectrometries of high energy neutron are generally performed by measuring the neutrons attenuated by various kinds of moderators using various neutron detector devices such as 3He counter, TLD, andtrack detector. Then neutron energy spectra are obtained by an iteration type unfolding method using
simulated spectra. This method, however, includes
uncertainty of the simulated results and iteration processes, and has problems of not measuring the highenergy neutrons. On the other hand , an unfolding
method using a pulse-height distribution measured byan organic liquid scintillator gives much more accurate
neutron energy spectra. 1- 3 ) This method, however, islimited by the scintillator size due to the leakage of therecoil protons generated in the scintillator, thus necessitating a huge scintillator to measure higher neutrons.
Therefore, we have developed a new type neutron spectrometer system (called Self-TOF detector) which canmeasure energy spectra of such leakaged protons in order to measure the neutrons of energy range 100 MeV'" 1 GeV.
This Self-TOF detector consists of an assembly of
a 150-mm x 150-mm x 5-mm-thick scintillator as aveto counter (VET), 20 sets of 100-mm x 100-mm x
6-mm-thick radiator-scintillator (RAD), a 100-mm x
100-mm x 5-mm-thick scintillator as a start timing
generator (STA), and 9 sets of 200-mm x 200-mm x
20-mm-thick scintillators as a stop timing generator(STO). The arrangement of the Self-TOF detector isshown in Fig. 1. All of the scintillators are NE102A
plastic scintillators. The STO was set at 120 cm after
the center of the STA. Thus, many of segments of RAD
and of STO give a high detection efficiency. Particles
emitted from RAD at angles of up to '" 16 degree canbe measured, and the efficiency at 100 MeV neutrons
is expected to be '" 1% according to the HETC-3STEP
Monte Carlo code4) calculation.
Protons induced at a forward direction by incident
neutrons in RAD pass through the rest of RAD and*1*2

High Energy Accelerator Research Organization (KEK)
Cyclotron and Radioisotope Center, Tohoku University

Start-scintillator(STA)

Fig. 1. The Self-TOF detector system.

STA, and are detected by one of the STO segments.
The proton energy (Ep) is estimated using the proton flight time (TOF-p) between STA and STO. Twophotomultiplier tubes (PMT) are attached to STA toobtain a good time resolution; the mean time of two
PMT outputs generates the start timing signal, which
are independent of the scintillation position in STA.
The initial energies of induced protons in RAD are obtained by adding the energy losses (~E) in RAD and
STA to the Ep obtained by the TOF method. The
radiator which generates protons can be easily foundby observing all outputs of the RAD segments, andenergy losses of the protons in RAD can be estimated.
In order to examine the detector performance and to
estimate the accuracy of detector response calculationby the HETC-3STEP Monte Carlo code,4) a neutron
irradiation experiment was performed using the quasimonoenergetic neutrons produced by a 10-mm-thick
7Li target bombarded by 135 MeV/nucleon Ht -ionsat the E4 neutron beam course of the RIKEN Ring
Cyclotron Facility. In this experiment, the response
function of the detector system for a monoenergetic
neutron was measured using only 6 sets of radiatorscintillators and 3 sets of stop-scintillators. The detector was placed behind the collimator at the position of
11 m from the Li target to STA in the neutron beamcourse as shown in Fig. 2. The coincidence events between STA and STO were selected, and all of the pulse
heights from each photomultiplier and the proton flighttimes (TOF-p) were stored in the event-by-event mode.
Incident neutron flight times (TOF-n) between the Litarget and STA were also stored using chopper trigger
signals of the cyclotron (repetition period: '" 1p,sec),
and the response of the detector for peak neutron energy (",132 MeV, FWHM:2.5 MeV) was obtained by
an off-line analysis. Time resolution of the detector
159

TOF-pFig. 2. Experimental setup at E4 neutron beam course in
RIKEN.

system, which was estimated from the I'-ray events, is""0.5 nsec, and the energy resolution at 132 MeV is",,20 MeV.
In a two dimensional plot of the TOF-p versus STO's
light outputs, proton, deuteron, and I'-ray components
can be seen in Fig. 3(a). The only proton eventswere selected as shown in Fig.3(b) by the help of energy loss difference in all radiators from their outputs.
Then, the TOF-p distribution was converted into theproton energy spectrum. Figure 4(a) shows an energy spectrum of protons generated from six radiatorscintillators measured with the center stop-scintillator.
In the distribution, knock-out protons are seen as thepeak, which is little broad because of proton energy
loss in the radiators. Figure 4(b) shows energy spectraof protons from one of the radiators measured with thecenter and side stop-scintillator, which were obtainedby adding the sum of the proton energy losses in RAD
and STA. These measured data are compared with that
calculated by HETC code. 4 ) The discrepancies are up
to ",,20% between measured and calculated responses
integrated in the peak region. On the other hand, lowenergy protons generated by carbon reactions are also
seen in the low energy tail, and measured data is about
twice as high as the calculated data. This can perhaps
be considered that a part of deuteron components areincluded in the measured data at the low energy tailby this discrimination method.
In this work, the experimental detector response wasobtained for 132 MeV monoenergetic neutrons, and it
is concluded that the energy of neutrons higher than
100 MeV can be measured with this detector system.
Neutron energy spectra can be obtained by an unfolding method using the response functions for various
neutron energies. Since the actual neutron spectra arerather broad behind the shielding in the accelerator facility and since a high resolution of energy spectrum is160

Fig. 3. Two dimensional plot of proton-TOF versus
stop-counter-light-output : (a) raw data, and (b) thedata after selecting only proton events.

2

~
~

=

I 6 radiators I
CenterStop-counter

~
I:

8=

~
::;:

I

=
~

Side
Stop-CounterCenterStop-counterExp.
- - Calcd.

8=

<:>

E 0.5
OJ
I:

=

~

~

60

XU

IOU

120

1010

60

HO

100

120

loll)

Proton Energy [MeV]

(a)

(b)

Fig. 4. Detector performance for 132 MeV neutrons,comparing with that calculated by the RETe code.
(a) Proton energy spectrum measured with the center stop-counter by flight time of the protons generated from six radiators. (b) Energy spectrum of protons from the 6th-radiator measured with the centerand side stop-counters after energy loss correction.

not required, this performance is enough for the neutron spectrometry and is expected to give more reliable
and more accurate results than any other methods toour knowledge. We are now ready to measure the response functions of complete setup of the detector for
higher energy neutrons, and to study the detector performance in order to obtain a much better energy resolution and discrimination of protons.
References
1) N. Nakao et a1.: Nucl. Sci. Eng. 124, 228 (1996).
2) H. Nakashima et al.: Nucl. Sci. Eng. 124, 243 (1996).
3) N. Nakao et a1.: J. Nucl. Sci. Technol. 34, No.4, p. 348(1997).
4) N. Yoshizawa et al.: J. Nucl. Sci. Technol. 32, No.7, p.
601 (1995).

RIKEN Accel. Prog. Rep. 31 (1998)

Proton Induced Activation in GSO, BGO Scintillators
M. Kokubun,·l E. Idesawa,·l K. Matsuzaki,·l T. Mizuno,·lY. Saito,·2 K. Takizawa,·2 and A. Yoshida
The Hard X-ray Detector(HXD) is one of the threeexperiments to be aboard ASTRO-E which is thefifth Japanese X-ray satellite scheduled to be launchedin the year 2000. 1) It covers the energy range from50 to 600 keV by the GSO(Gd 2Si0 5; Ce) scintillators located at the bottom of a "well" made of the
BGO(Bi4Ge3012) scintillators.
In the orbit of the satellite, there are energetic ('" 100MeV) protons which are trapped by the earth magnetic
field and these particles will produce radioactive isotopes in the scintillators. Because these radioactivities
are considered to become the dominant background for
the HXD, it is important to study the characteristicsof the effect of radio activation on the ground.
vVe irradiated the GSO and BGO scintillators with
the Ht particles which were accelerated to 135 MeV lu
at RIKEN Ring Cyclotron, and measured the induced
radioactivities. The intensity of the beam was set to
extremely low level ('" 106 counts I sec) in order to accurately count the number of Ht particles which had
penetrated the two plastic scintillators located vertically to the beam upstream of the target scintillator.
Total ",109 Hts were counted and this corresponds tothe amount that one GSO is to be irradiated for about
100 days in the orbit.
Two radioactivated GSO scintillators were measured, one by a germanium detector to identify the radioactive isotopes produced and the other by a PMT toknow the actual response against the radiations inside
the GSO. Table 1 shows the identified radionuclides
corresponding to their half lives.
Within a few days after irradiation, complicated andvariable spectra from the radionuclides shown in thefirst row of Table 1 were obtained through the PMT.
Though they might confuse the observational datain the orbit, it is expected that most events caused
from these short-life nuclides can be rejected by thephoswich technic and anti-coincidence methods at the•1*2

Table 1. Identified radionuclides.

Half life ('T)

identified nuclide'T ~ 1dayT ~ 30days'T ~ 30days

156Tb, 155Tb, 153Tb, 149 Gd
147 Gd, 147 Eu, 146 Eu, 145 Eu
153Gd, 151Gd, 149 Eu, 146Gd, 145Sm

BGO shield surrounding the GSO scintillators.
On the other hand, the spectra which were observed
long time (more than 30 days) after the irradiation canbe explained by the nuclear emissions radiated in theradioactive decays of only 5 or 6 radionuclides shownin the last row of Table 1. Though they can not berejected from radioactivational backgrounds, becauseof their low energy ('" ~ 200 ke V) gamma ray emissions which can be stopped within the GSO scintillaor, we will again be able to subtract these longterm, stable backgrounds by using the off-source observational data. Furthermore, we have successfully
obtained the Monte-Carlo simulated spectra which are
expected from the radioactivated GSO scintillator readthrough a PMT, based on the nuclear data of the identified radionuclides. This simulation has reproduced
more than 95% of the experimental data within theenergy range from 50 to 500 keV. Therefore, the simulation can be another tool to understand the actual
background of the HXD in the orbit.
References
1) T. Kamae et al.: Proc. SPIE 2806, 314 (1996).
2) K. Matsuzaki et al.: RIKEN Accel. Prog. Rep. 27, 118(1996) .

Department of Physics, University of Tokyo
The Institute of Space and Astronautical Science

161

RIKEN Accel. Prog. Rep. 31 (1998)

In-Vacuum Plastic-Scintillator Hodoscope for Low-Background
Measurements of Charged Particles
1. Hisanaga, T. Motobayashi, and Y. Ando

A vacuum chamber has been constructed, so thatthe plastic-scintillator hodoscope for Coulomb dissociation experiments 1 ,2) can be mounted inside of it for
reduction of background. In the last experiment thevacuum was sealed at 5 m downstream of the target
just in front of the hodoscope, because the hodoscope
was installed in the atmosphere. The window which
sealed vacuum from air caused background reactions.
The overall thickness of the window (mylar) and air
was about 10- 2 g/cm 2 , which was comparable to thetarget thickness. Therefore, the yield from the background was comparable to that from the target. In thepresent setup, on the other hand, the relevant background was entirely eliminated.
The hodoscope system was set 5 m downstream ofthe secondary target position of the RIKEN Projectilefragment Separator (RIPS) , and measured the fragments, p and 8B, produced from the 9C + natPb interaction. t
Figure 1 shows a schematic view of the setup. The
hodoscope consists of ~E and E walls with 5 and 60
mm thickness, respectively. The time of flight method
was employed to measure the energies of the fragments.
The ~E and E counters, which cover 1 xl m 2 area,
were divided vertically to 13 segments and horizontallyto 16 segments for coincidence measurements of pluralcharged particles. The width of the ~E strips was 40
mm or 100 mm, while that of E strips was 30 mm or
75 mm. The central detectors have narrower width inorder to stand for higher counting rates. Two Photomultiplier TUbes (PMTs) were coupled to both ends ofeach strips and measured the difference of arrival times
to determine hitting positions.
We mounted the PMTs outside the vacuum chamber
to avoid possible electric discharge in PMT bases. The
mechanical construction around the PMT is shown in
Fig. 2. A plastic light pipe per PMT sealed the vacuum chamber and also guided the light from the scintillator to the PMT outside the chamber. In vacuum,
the scintillators and the light pipes were communicatedacross transparent rubber pads . Good optical contact
was achieved due to the atmospheric pressure pushing
the pads. Because the light pipes are allowed to moveagainst the chamber wall, the corresponding motion of

The aim of this experiment is to measure the 8B(p,,)9C
synthesis reaction cross section of astrophysical interest indirectly. The inverse process, Coulomb dissociation reaction
9C -t 8B + p corresponds to the 9C(virtual- "p)8B reaction, where the virtual photon(r) is produced during thecollision between the projectile and the target.

162

Fig. 1. The setup for 9C ----t 8B + p Coulomb dissociation
measurement.

Chambe r Wa I I

Opt ical Interface!
(Transparent Rubber )Scint i Ilator

Fig. 2. Structure around the PMT.
flange dose not give too large stress to the scintillators.
The pressure in the chamber achieved 7 Pa with a2500 l/min oil-sealed rotary pump. This pressure isequivalent to the thickness of 10- 5 g/cm 2 , and wasenough to realize the primary aim.
References
1) T. Motobayashi et al.: Phys. Rev. Lett. 73, 2680 (1994).
2) T. Kikuchi et al.: Phys. Lett. B 391, 261 (1997).

RIKEN Accel. Prog. Rep. 31 (1998)

Beta-Ray Imaging Detector Using Scintillating Fibers
K. Morimoto and F. Tokanai
Genomic Linkage Map data l ) are provided by meansof autoradiographic films. This technique allows thedetection over a large surface (35 x 43 cm 2 ) area withexcellent spatial resolution (rv 50 p,m). 3 2 p are currently used for landmarks. However they have two
shortcomings: long exposure time (about two weeks)and lack of quantitative information.
To improve them, we are developing an imaging detector using scintillating fibers. This detector consistsof two layers (X and Y layers) of scintillating fibers coupled to multianode photomultiplier tubes (MA-PMT).
Each layer consists of 512 fibers with the cross sectionof 0.8 mm square (BICRON BCF-12 type). To reducea dead space of fiber-belt the square type fiber waschosen.
Furthermore, to avoid using too many MA-PMT detectors and electronics, we used a matrix method asshown in Fig. 1. Each side of 256 fibers was arranged
into a 16 x 16 matrix. At the one end of fiber matrix is
attached to a MA-PMT to read lateral 16 lines information and the other side is to read vertical 16 lines
information. One of the MA-PMT gives the information package of 16 fibers (belt) and the other gives individual information of each package of 16 fibers (strip).
Therefore, 256 fibers can be encoded by the two 16 ch
MA-PMT. The signals from MA-PMT are sent to adiscriminator whose threshold level is variable for eachchannel. Moreover, MA-PMT noise can be reduced bytriggering the events which coincide between each sideof fibers and each layer.

and Y-axis are shown in Fig. 2 and 3, respectively.
These spatial resolutions for the 3 mm diameter betaray source are 4.8 mm (FWHM) for X-axis and 5.6 mm(FWHM) for Y-axis, respectively. The cross talk ratio
is low, less than 5%.

1000

500

o

Jl
50

100

150

200

250

Fiber Numbers

Fig. 2. Scintillation fiber projection on the X axis for the
3 mm diameter 207Bi .

Projection Y
1200 "--~""""'-~""""""~"""""'~"""--~~

1000

!l

1100

g

600

C,)

400
200

50

100

150

200

250

Fiber Numbers
Fiber Number
1

Fig. 3. Projection on the Y axis at the same event as X
axis.

",

Iii

j

Belt 1

....
32

:
I

,W,~lJ,J

~

SIri

j

B.II
B.112

I
I

:~ =:J

B

12·· .. 16

PMT(R5900)Belt 16

PMT

Fig. 1. Repart ition of the 256 scintillating fiber unit extremities on t he MA-PMTs.

These detectors include four identical sets of scintillation fiber in order to cover the genomic sheet, twoof them give X-directional position the others give Ydirectional position. These four detectors cover 43 x 43
cm2 area.
The spatial resolution and cross talk of this detector
were measured using the 1 MeV and 0.5 MeV internalconversion electrons from a 207Bi source with a diameter of 3 mm. The position histograms for the X-axis

The problem still to be solved with this detector is its
efficiency. It is about 0.5% which was estimated fromthe ratio of a detection rate to the source intensity.
This relatively poor efficiency is explained by the low
gain of the MA-PMT. To solve this problem we will
try to put an amplifier between output signals of MAPMT and discriminator.
A charged particle deposits the energy more than abeta-ray in the scintillation fibers at the same incident
energy. Therefore, this type of detector can give a good
S IN ratio and a good spatial resolution for charged
particles. Therefore, this detector has the possibilityof being a position sensitive charged particle detector
for accelerator experiments. Currently we are making
detectors using thiner fibers whose size is 400 p,m and
250 p,m.

References
1) Y. Hayashizaki et al.: Genet . Soc. Am. 138, 120 (1994).

163

RIKEN Accel. Prog. Rep. 31 (1998)

Development of a Fast Two-Dimensional PPAC
H. Kumagai and I. Tanihata
A two-dimensionally position-sensitive PPAC (Parallel Plate Avalanche Counter) for high counting-rate
application has been developed for low-energy radioactive ion beams at the RIPS in RIKEN. A delay-line
readout method has been used to pickup electroninduced signals from stripped cathodes. An electroninduced signal has a fast rise time and a fall time ofabout 4 ns , and is thus thousand times faster than thesignals from ions, that are used in the previous model.
The previous model 1) used the charge-division
method for position determination and gave a goodresolution and linearity. That model has been used
for monitoring the position profiles of radioactive ion
beams. However a pile up of signals becomes serious
when the counting rate is higher than a few thousand
per second. This is a natural limitation as long as one
uses slow ion signals (rise time of 3 J.Ls). In contrast thepresent delay-line read-out model provides a good position information for a counting rate as high as 106 /s.
The delay-line readout was reported 2) previously by
several authors, but the posit ion information was discretized on the strip position. In the present model,
a position is read continuously without break. Thiscondition was obtained after a adjustment of the risetime of the signal, electrode spacing, and delay line.
The cathode layout is shown in Fig. 1. The 2.40 mm
wide strips with 0.15 mm inter-strip spacing are madeby evaporation of Au with 30 nm in thickness. Thebase material is 1.5 J.Lm Myler foil and is mounted onto
aGIO frame of 2 mm thickness. The number of strips
is 40 in both X and Y directions and thus provides
the sensitive area of 100 x 100 mm 2. Each strip isconnected to the delay-line taps described below.
The lumped-constant type delay line was used. The
110 mm long solenoid was wound by 0.3 mm¢> Cu wire
onto a 2 mm¢> bakelite rod. The taps are made every
8 turns of coil. Then 39 pF capacitors are connectedfrom the taps to the ground . The signals from thestrip electrodes are also connected to these taps. Thisdelay line had a 55 n impedance and a delay of 0.80
ns/mm. The attenuation measured by signals of 4 ns
rise and fall times, signals from a rays, was 15% inwhole length. The rise time of 4.7 ns was observed after
the transmission of the signal through the delay line.
The combination of 4 ns rise time and 2 ns inter-strip
delay time provided the best result for the linearity of~=======r5,- Solenoid
Coil

40 strips

Condensers
C=39pFthe position information.
The anode was also made by Au evaporation onto
the same Mylar foil on a same frame. The spacing
between the anode and the cathode was 4 mm. The
detector windows were made of 4 J.Lm Mylar foil with
evaporated Al on the surface. The detector gas was 10
Torr C3Fs and the operating bias was 880-900 Volts.
The integrated linearity obtained by an 241 Am alphasource is shown in Fig. 2. As seen in the figure, within±45 mm from the center of the detector, the errors are
smaller than ±0.05 mm for both X and Y directions.
The error increases rapidly beyond 45 mm from thecenter. The position resolution within this ±45 mm is(J = 0.3 mm.
The differential linearity for ~x = 2.5
mm is better than ±1.5%.

E
5

0 .1

~

0.0

.

f ~. 1

Ii

-50

-40

-30

-20

· 10

0

10

20

30

40

50

Position (mm)Fig. 2. lntegrallinearity of the PPAC.

The efficiency of the PPAC was tested by a 14.5A
MeV 7Be beam to be 83%. This efficiency is somewhat
lower than the previous charge division type PPAC. It
is considered to be due to the smaller induced signal
from electrons. Therefore the present detector is effective only for low energies or for large Z particles athigher energies.
The total delay time of the delay line is 80 ns andit gives a resolving time of the detector. Positions of
two or more particles coming into the detector within
this time interval are not determined. However thesum of the TDC readout from the two ends of thedelay line provides the hit multiplicity test. (The timedifference is used for the position determination.) The
time-sum from a single-particle hit does not dependon the position of the hit , but it shifts for a multiplehit event. Therefore a shift of the time-sum indicatesa multiple-hit event. This multiple-hit rate was only
9% of the total events even for an operation under thecounting rate of 106 /s. The position resolution was(J" = 0.4 mm under this condition.
A 4He beam of
2A MeV was used for this test. It is recommended,however, to keep the counting rate below 250 kcps forlong-term stable operation.
References

Fig. 1. The cathode structure of the delay-line PPAC.

1641) H. Kumagai and K. Yoshida: RlKEN Accel. Prog. Rep.
28 , 127 (1995).
2) S. Beghini, L. Corradi, J. H. He, and A. Dal Bello: Nucl.
lnstrum. Methods Phys. Res. A 362, 526 (1955).

RIKEN Accel. Prog. Rep. 31 (1998)

A Large Area PPAC lIonization Chamber
K. Yoshida, M. Shimooka, R. Wada, T. Nakagawa, K. Nakagawa,1. Tanihata, Y. Aoki, and J. Kasagi
A large area parallel-plate avalanche counter(PPAC) and ionization chamber array has been constructed for the detection of fission fragments froma very heavy compound nucleus with mass A~300.
Recent theoretical calculation suggests a formation ofsuch a heavy compound nucleus by the collision between heavy nuclei such as 208Pb + 208Pb. A heavy
compound nucleus, if it is formed, will decay to plural
fragments by fission. The present detector is designed
to detect such fragments to investigate formation ofheavy compound nuclei. In order to distinguish the
products from deep inelastic reaction, we focused on
the detection of all the fragments from a ternary fission of heavy compound nucleus. The fragments fromusual binary fission are less informative for the case,since they distribute in space similar to the reaction
products of deep inelastic reaction.
The detector is designed to cover 25- 75° in laboratory angle with respect to the beam axis. In order toobtain a high detection efficiency, it covers most of theregion where the three fragments are expected. The
forward angles in laboratory frame are excluded since alarge number of elastically scattered beam particles are
expected. As shown in Fig. 1, the detector is divided
azimuthally to 12 identical units with a minimum deadspace in between. Each unit is further divided into
four sub-sections inside. Each sub-section consists ofa PPAC and an ionization chamber (IC). The PPAC
provides a position and ,a time-of-flight (TOF) informations. The IC gives energy of a fragment. In or-

der to obtain a reasonable mass resolution (::;10% in
FWHM), the flight path is set to be 50 cm.
The PPAC consists of one anode and two cathodes
placed at the both sides of the anode in the distanceof 2.5 mm. The position is obtained by the delay line
method. The cathode strips of 4.7 mm in width areformed onto the 1.5 J.1.m mylar foil by evaporating the
60 J.1.g/ cm 2 gold with a 5 mm pitch. Each strip is connected with a 2 ns delay chip in between. The anodeis made of the 1.5 J.1.m mylar film coated with the 60
J.1.g/cm 2 gold in both sides. The timing signal is obtained from the anode.
The IC consists of an entrance window, a Frisch grid,and an anode. The entrance window is a 4 J.1.m aluminized mylar attached to a stainless-steel honeycomb
mesh with a 20 mm cell size and 0.15 mm in thickness. It sustains the pressure difference up to 150 torr.
The window keeps the ground potential and electrically works as a cathode. The Frisch grid is made of a
1.5 x 1.5 mm2 stainless-steel mesh with a line width of
0.1 mm. It is placed at 170 mm from the entrance
30
25
20
~

d

cd
r.x..
0

""-/

~

15
10
5
0
-5
-10

0

100

200

300

400

E (a.u.)
250
225
1-<

a)

200

.D

E

175

::l

150

Z

125

CI:S

100

en
en

::E

75
50
25
0

40

60

80

e (deg)Fig. 1. Overview of the PPAC/ionization chamber.

Fig. 2. TOF vs. E plot (a), and mass vs. theta plot(b), obtained from the 129Xe + 209Bi reaction at 7
MeV /nucleon Xe beam.

165

window and the voltage 15-20% lower than the anode is applied. The anode is made of a printed circuitboard and placed 10 mm apart from the grid. Field
shaping grid is placed near the side wall of the chamber to form a homogeneous electric field between theentrance window and the Frisch grid.
The detector was tested with 129Xe beam at 7
MeV /nucleon delivered from the RIKEN Ring Cyclotron (RRC). The targets used were a self-supported
209Bi foil of 1 mg/cm 2 in thickness and a 1 mg/cm2
The
232Th foil backed with 16 /-Lm aluminum.
detector was irradiated by the elastically scattered
129Xe with energies from 6.2 MeV/nucleon (25°) to
2.5 MeV/nucleon (75°) for the case of 209Bi target and with energies from 4.7 MeV/nucleon to 2.1
MeV/nucleon for the case of 232Th. Both of the PPAC
and the IC were operated with same isobutane gas but
in different pressure; 5 torr for PPAC and 150 torr for
IC. The applied anode-cathode voltages are 480 V for
PPAC and 1500 V for IC.

166

A two-dimensional plot of TOF vs. energy deposit E
in the IC obtained for 129Xe + 209Bi reaction is shownin Fig. 2(a). TOF is obtained from the time difference
between the PPAC signal and the RF signal of theRRC. The intensive locus at the large E and fast TOF
is the elastically scattered 129Xe. Target-like products
are also seen at the region of the small E and the slow
TOF. The masses of detected particles were deduced
from the TOF and E after correction of the energy
loss of the particles in the PPAC and in the entrance
window of the IC. The result is shown in Fig. 2(b)against the detection angles. The energy loss correction were 20% (25°, 6.2 MeV/nucleon) and 50% (80°,
2.5 MeV/nucleon) for 129Xe. The gap seen in Fig.
2(b) between 50° and 55° is due to the dead space ofthe detector. Elastically scattered 129Xe is clearly seenat 25- 60°. In_larger angles, elastic event was not observed since the grazing angle is 49° for the reaction.
The mass resolution of 10% in FWHM is obtained forthe 129Xe.

RIKEN Accel. Prog. Rep. 31 (1998)

ANew Fluorescence Photon Detection System for
Collinear Laser Spectroscopy
S. Ozawa, T. Ariga, K. Ikegami, N. Inabe, M. Kase, T. Katayama, T. Kubo, H. Okuno,
I. Tanihata, M. Wakasugi, Y. Watanabe, Y. Yano, and A. Yoshida
In order to measure the atomic transition energy
precisely in the high-energy and highly-charged ion
beams, we have constructed an ultra-law background
fluorescence detection system. We tested the systemby measuring the D 1 and D2 transitions in the Lilike 11 B2+ ion (primary beam) accelerated up to 11.25
MeV / nucleon.
The experimental setup is shown in Fig. 1. The ion
beam and the laser beam collide each other at the collision point. Excited ions emit fluorescence photons
during the flight, and they are detected by the fluorescence detector. The fluorescence detector consists ofa charcoal panel which can be cooled down to 18 K,
optical filters, lenses, and photomultipliers. Since thecooled charcoal panel can make the vacuum of detector region two orders of magnitude higher than that at
temperature of 298 K , the noise from the collisions between residual gas and ions was dramatically reduced.
In fact, the noise signals from the second bunch of theion beam completely disappeared at 18 K as shown in
the timing spectra of Fig. 2. Since the laser beam collides with only the first bunch, the peak at the firstbunch at 18 K contains fluorescence signals without
noise. Dichroic filters and four movable collimators
were placed to suppress the scattered light of laser
beam. Small reflection rate of light of the charcoal
panel was also effective to reduce the stray photons
from laser beam.

100
from Laser Pulse.Q~.- 0 - -

80

*

Q)

IV
a: 60

1

en

~
c:
:J

0

--------

from 1st. Bunch

40

0

T=18 K
T=298 K

from 2nd. Bunch

I

c:
0

"0 20
.l:

Q.

20

40

120
Time (ns)Fig. 2. The timing spectra measured with PM at the twodifferent temperatures of the charcoal panel: 18 K withlaser and 298 K without laser.

200. Transition energy of the Dl and D2 were estimated to be 48346.8(33) and 48380.0(33) em-I, respectively. Both values are about 12 cm- 1 smaller thanthe NBS values.!) Those differences are due to errors in
the wavelength calibration. The counting rate of thefluorescence was found to be 3.3 x 10- 6 counts/ion,which is more than forty-times better than the lastexperiment. 2)
40

-e

~

02

35

01

30

]!:o

II
Laser

~

25
20

CI>

u

c:

15

~

10

~

u:

5
0

Fig. 1. The ultra-low background photon detection system.

"241.200

241.400
241 . 600
Wavelength(nrn)

241 . 800

242 .000

Fig. 3. The fluorescence spectra due to the Dl and D2
transitions.

The velocity of the ion beam was derived to be

f3 = 0.15394(7) from the magnetic field strengths ofthe dipole magnets of RIPS. Taking a timing gate
at the first bunch in Fig. 2, the fluorescence spectra
due to the D1 and D2 transitions were obtained asshown in Fig. 3. The signal to noise ratio was about

References
1) C . E . Moor: Atomic Energy Levels, NBS, Washington
D.C. USA, (1949), p. 19.
2) M. Wakasugi: Phys. Scr. 73, 70 (1997).

167

RIKEN Accel. Prog. Rep. 31 (1998)

Final Calibration of Cosmic Ray Heavy Ion Telescopefor First Brazilian Scientific Satellite
T . Kohno, H. Kato, H. Miyasaka, and K. Nagata
An international collaboration of cosmic ray heavy
ion observation with the first Brazilian scientificsatellite! ) is now being proceeded. It is planned to belaunched around May 1998 by Chinese rocket, Long
March. Our Japanese side is in charge of detector
telescope including charge sensitive pre-amplifier andthe detector bias voltage supply. The Naval ResearchLaboratory (NRL) of the United States is in chargeof analogue circuit including ADC, and the InstituteNacional de Pesquisas Espaciais (INPE) of Brazilianside is in charge of digital circuit and interface for thesatellite system. This instrument is named as ORCAS(Observac:;oes de Raios-C6smicos Anomalos e Solaresna Magnetosfera in Portuguese) that means observation of anomalous and solar cosmic rays in the magnetosphere .
We have two telescopes for ORCAS, one (namedPRE) is for electron, proton and alphas with a small
geometric factor; and another (named MAIN) for theheavy ions from He to Ne (high gain mode) and fromC to Fe (low gain mode) . But, we report here only
the MAIN telescope due to small space of paper. The
whole electronics for the flight model were gathered
to RIKEN from Brazil and US this time. The threeparts of telescope, analog circuit, and digital circuit
were connected and tested. The cross sectional viewof the MAIN telescope is shown in Fig. 1.

MAIN B(Ar 95MeV / nuc)

Dl fronL HiZ mode Omm degrader

I

1000
500
0
1000

Dl

D2

1

500
0
1000

D3

c:

500

A

:0

.:: 10000
~

C1l

.D

E

;:l

Z

D4

l

500
0
1000

D5

500

A

0
1000

D6

500
0
1000
D7

500

o

o

500 .

1000

1500

2000

En er gy( MeV)

Fig. 2. Pulse height distributions in each detector.
Ar-beam enter into Dl and stopped at D5. No Al platein this case.

ORCAS/ MAIN

T1Tn;cw.

1000[~, r <,
I";"::.. ;\>;..."

>

'"

~

'"
<l

500

I

Df(O.2m-m 48X48mTn))t~;i,~~~~t~'D7(O.2mm 48X48Tnm)
D2-D6 (tTnTn 28X28 Tnm.)

500

Fig. 1. Cross sectional view of the MAIN telescope.

We performed the final calibration test with Q and
40 Ar beams.
Using Al plates having various thicknesses in front of the telescope, we took data of ADC
output in list mode for the beam with various energies. The beam energy was 45 MeV/nucleon and 95
MeV /nucleon for Q and Ar, respectively.
We show in Fig. 2 an example of pulse height distributions in each detector. The beam comes into D 1 andstopped at D5. The detector thicknesses are shown in
Fig. 1. We can see an increase of the pulse height after
Dl due to decreasing particle energy.
Shown in Fig. 3 is the L).E-E scatter plots for Ar
168

1000

1500

2000

2500

3000

ET (MeV)Fig. 3 . .6.E-E scatter plots for Ar-beam. Various Al thickness data are included . .6.E (ordinate) means the energy
deposition in a detector just before the stopped detector, and total E (abscissa) is sum of .6.E plus energy
deposition in the stopped detector.

beam. We can see tracks of the secondary elements
produced by the nuclear fragmentation in the Al plate.
References
1) A. Thrtelli et al.: Proc. 24th Int. Cosmic Ray Conf.,
Vol. 4 (SH session) , Rome, Sept ., 1995, p. 1275.

RIKEN Accel. Prog. Rep. 31 (1998)

Performance Study of Radiation Detectors for Spacecraft
T. Goka, H. Matsumoto, T. Omoto, T. Kohno, Y. Muraki, K. Masuda, Y. Matsubara, I. Imaida,
T. Sako, H. Tsuchiya, K. Taguchi, 1. Tanaka, M. Fujii, and M. Nakazawa
The contribution of neutrons to the radiation exposure of astronauts has largely remained as an ignored
problem. The problem of detecting neutron in spaceis difficult due to the intense charged particles (proton, etc.). In order to detect the solar neutron in themixed field of neutrons and charged particles, we havedeveloped a scintillation fiber detector. A proto-typeof a scintillation fiber detector was tested with accelerator in 1996-1997. Signals from scintillation fibers
are read by a system of multi-anode photomultipliers
and CMOS LSI l ) which consumes electric power very
little.
Experiment. The purpose of this experiment was toconfirm response of the scintillation fiber detector byproton. The energy of an incident neutron was able
to determine by measuring the path lengths of the
track of a recoiled proton and from the known incident
direction. The test detector prepared for the experiment was a cubic arrangement of scintillation fibers
with a volume of 1000 cm 3 . Each unit of scintillation
fibers (16 x 16) have a width of 3 mm and a heightof 3 mm as shown in Fig. 1. Two multi-anode photomultipliers (MAPMT, Hamamatu 4140-20) were used
to read fiber's signal. Each MAPMT has 256 channels. Signals from outermost fibers facing toward thebeam are used to veto charged particles in case neutrons are measured. E3 facility of Ring Cyclotron at
RIKEN was used for the experiment in December 1996
and July 1997. The ion species of the beam were Ht(Ht -+ H+ + H+). The energy of the beam was 135
MeV In in 1996 and 110 MeV In in 1997. One set ofmeasurement was to measure the track lengths of protons in different energies. We changed the beam energy by using 20 to 70 mm thickness Aluminum (AI)degrader. A 135 MeV (110 MeV) proton dissipates allof its energy in the 70 mm (60 mm) thickness degrader,
and the irradiation particles to reach detector are neu-tron only. We had confirmed neutron track on above
configuration. Another test was to detect images ofneutrons and determine their energies
Test Results. There are two orthogonal planes on
which tracks of particles are projected. In each measurement, an ADC value at each fiber is recorded. Inorder to determine the particle, the tracks of isolated
pixels without any adjacent signals are removed. An
example of neutron event after subtraction of such isolated pixels is shown in Fig. 2. The energy of incident
proton was determined using their track lengths. Theenergies thus determined were compared with these expected as a function of the thickness of AI. In Fig. 3
preliminary results are plotted together with expectedvalues. Based on the results of the test experiment at
RIKEN in 1996 and 1997, improvement of the detector, data taking system, and analyses methods are in
progress.

x

y

•

•
•
•••

••
••

Neutron Irradiation Test

Fig. 2. An example of neutron event after subtraction ofisolated pixels.

;~

>-

~

150~~~~~~~~~~~~~
Proton range
on detector size

(9tmm)

Q)

~

2

t

100

T

e

~
E

't-

50 --

T

'---1·· ....

lL--------II~~

'0

c

o

• .qt.

Vl

•

0..

~

o

U

o

' Theory
Experiment
10(Peak)

20

30

40

45

Thickness of AI (mm)Fig. 3. Preliminary results of measurement of proton
range distribution.

References
Fig. 1. Structure of scintillation fiber detector.

1} H. Ikeda et al.: IEEE Trans. Nucl. Sci. 38, 135 (1991).

169

RIKEN Accel. Prog. Rep. 31 (1998)

Fabrication of the Muon Magnet for the RHIC SPIN Project
T. Ichihara, H. En'yo, Y. Goto, N. Hayashi, K. Imai, A. Masaike, N. Saito,
T.-A. Shibata, Y. Watanabe, and M. Ishihara
Muon magnet is one of the detector magnets to beinstalled in the PHENIX detector in order to analyze
the momenta of muon and muon-pair with high resolution. RIKEN is taking a role of fabricating the Muon
Magnet South (MMS). It is about 8 m tall and weighsapproximately 200 metric tons.
The contract between RIKEN and Mitsubishi Electric Cooperation (Meleo) was initiated in March 1996
for the MMS fabrication. In the previous report, we
introduced the basic design concept of the MMS.l)
Preliminary design review (PDR) for the MMS was
performed in May 1997 at the Lowrence Livermore National Laboratory (LLNL). Basic design concept wasapproved at the PDR. The detailed design work for the
fabrication started after the PDR. Final design review(FDR) was carried out in July 1997 at the Brookhaven
National Laboratory (BNL). At the FDR, a small modification was required to keep enough rooms for tracking detectors. This requirement was resolved by changing the configuration of the coil bus flags.
The construction of the MMS was completed in
February 1997 at Meleo Kobe Works. 2 ) The inspectionof the magnet was done on 26th and 27th in February
1997 with the attendances of RIKEN, Kyoto Univ.,and LLNL. Figure 1 shows the photograph of the MMS
during the inspection. Following items were inspectedor tested at the Kobe Works.
For Coils
CD Pressure and leak tests@ Resistance check® Measurement of the insulation resistance@ Inductance test
® Impulse test
® Dimensional check and assembly check(j) Measurement of the pressure drop
® Dielectric test
® Dimension check@ Magnetic field measurement
For Steels
CD Lower plate level and back plate vertica® Back plate flatness® Back plate center height@ Piston head center height® Difference between piston head and back plate center® Difference between piston root and back plate center(j) Relative position of teacup to back plate® Relative position of lampshade panels to piston® Relative position of lampshade panels to back plate@ Appearance(]) Inspection of pars170

Fig. 1. Photograph of the MMS during the inspection at
Meleo Kobe Works. (Photo taken on 26th Feb., 1997) .

No problem was found at the inspection. After theinspection, the whole magnet components were packed
and transported to the BNL by ship. All the MMS
components arrived at the BNL in April 1997 without
damage. The assembly of the MMS has been started at
the PHENIX experimental hall at the BNL in November 1997. Figure 2 shows the MMS during the assembly at the BNL. After the completion of the assembly,
the mapping of the magnetic field is scheduled.

Fig. 2. Photograph of the MMS during the assembly at
the PHENIX experimental hall at the BNL (Phototaken on 25th Dec., 1997).

References
1) T. Ichihara et al.: RIKEN Acce!. Prog. Rep. 30, 155(1997).
2) see for http://www.rarf.riken.go.jp/rarf/rhic/mms/

RIKEN Accel. Prog. Rep. 31 (1998)

Plan of Computing Facility for RHIC Spin Project
Y. Watanabe, T. Ichihara, N. Saito, A. Taketani, and M. Ishihara
The RHIC 1 ) (Relativistic Heavy Ion Collider) spin
project 2 ,3) is going now well into the latter half of its
construction phase. One of the biggest remaining issues is the method and facility to cook data from theexperimental setup.
PHENIX 4 ) (a major detector of RHIC) is the mostimportant detector to investigate the RHIC Spinphysics, and is designed to produce 20 MBytes/s ofdata. The data will accumulate more than 200 TBytes
in a year. It is not trivial issue to store and analyze
such a big volume of data. On the other hand, the
RHIC has other three experimental detectors (STAR,5)
PHOBOS,6) BRAHMS 7 )); they have the same problem. The total amount of whole RHIC's data will reachmore than 1,500 TBytes in a year. Therefore, a RHIC
collaboration intends to assemble a big computing facility named RCF (RHIC Computing Facility)8) to beplaced at BNL (Brookhaven National Laboratory).9)
Some important numbers which describe a planed
capability of the RCF are following:
Total CPU Power
Fixed disk
Tape robots capacity
Speed of data archive
Total capacity of tapes

f'J 20,000 SPECint95
40 TBytes
250 TBytes
200 MBytes/s
1,700 TBytes / year

These numbers indicate that the RCF will consist of
more than 1,000 of recent fastest workstations, morethan 1,000 of recent largest fixed disks, and a biggest
tape storage system in the world. RCF will consume
more than 30,000 tapes in a year. Such incredibly big
numbers show that the RCF is one of the biggest computing facility in the world. However, the capability is
expected not enough yet. For example, the tape robots
can handle only 1/7 of the tapes produced in a year.
The RHIC Spin Project promoted by RIKEN,
wishes earnestly to operate a computing facility(PHENIX-CC-J 10 )) which has similar capability of the

RCF, in order to make the physics outputs definite.
The actual scale of the facility is currently under consideration. On the other hand, the capability will cover
not only analyses of the data from detectors, but also
simulations of physics modeling, detector responses,etc.
A key issue to operate such a big facility efficiently
is to develop technologies which make many CPUs (f'J
100) work coherently. Making the prototype for thispurpose is an R&D work of the next Japanese fiscal
year (JFY1998).
Another key issue that we should pay special attention is a method of data transfer between U.S andJapan. It is not trivial to transfer data more than 100
TBytes in a year. The network connection over the
Pacific Ocean may be too expensive. Transporting oftapes by airplane is another possibility. However, it
is not easy to put data which are distributed in the
robots of the RCF into a set of sequential tapes. We
need a special data duplicating facility to be attachedto the RCF. We will start an R&D for such a facility,
too in the early JFY1998.
We acknowledge Prof. Hideki Hamagaki, Prof.
Jyunsei Chiba, and Prof. Ryugo Hayano for their close
discussions with us.
References
1) http://www.rhic.bnl.gov/
2) H. Akikawa et al.: RIKEN Accel. Prog. Rep. 31, 52(1998).
3) http://www.rarf.riken.go.jp/rarf/rhic/4) http://www.rhic.bnl.gov/phenix/5) http://www.rhic.bnl.gov/STAR/6) http://phobos-srv. mit. edu/
7) http://www.rhic.bnl.gov /exportl/brahms/WWW /brahms.html.
8) http://www.rhic.bnl.gov/html/RDG.html
9) http://www.bnl.gov/10) http://www.rarf.riken.go.jp/rarf/rhic/rhic-cc-j

171

RIKEN Accel. Prog. Rep. 31 (1998)

Factory Plan for PHENIX Muon Identifier
A. Taketani, K. Kurita, M. Ishihara, T. Ichihara, Y. Watanabe, N. Saito,
N. Hayashi, H. En'yo, Y. Nakada, H. Sato, K. Imai, H. Torii,
T.-A. Shibata, T. Sakuma, E. Taniguchi, and Y. Mao
A progress of the two PHENIX muon identification
detector (MUID) in the fabrication factories is summarized in this paper.
The muon identification is quite important for RHIC
spin project. For example, W boson may have a flavortagged spin information. l ) The W boson can be identified easily with a high Pt muon. We will cover the forward and backward regions of PHENIX detector withso called MUID panels. The covered azimuthal angle
is from 10 to 35 degree.
There are two differently size MUID panels tocover the MUID fiducial volumes.
We need 20
small panels [2.9 m(H) x 4.4 m(V)] and 40 large panels [5.4 m(H) x 5.6 m(V)]. The small panels are assembled in KEK, and the large panels are assembled
in Brookhaven National Laboratory. We will start thepanel production in Dec. '97.
The two Iarocci tubes 2 ) are staggered by half a cellinterval to maximize the detection efficiency. Thesetubes are taped to the both sides of the Al mid-plane.
The tubes are oriented horizontally in the front layers and vertically in the back layers. The Al frame
supports the mid-plane. The tubes are protected fromoutside by Al cover plates. One end of the tube isconnected to the readout electronics.
The tubes are produced at an Italian manufactureand shipped to our factories in Japan and USA. The
received tubes are checked one by one, and only theones which meet our criteria are installed on the panels.
At first the tubes are checked for their physical size.
The resistance and capacitance between anode wireand ground wall are measured. Then, the gas flow
system is connected to the tubes, and gas leakage ismeasured with manometer. The 5 kV high voltage(HV) is applied to the wire after replacing the gas volume with the working gas. After applying the HVfor 5 days, the preamplifiers are connected to the wire
and tested with cosmic rays. The pulse height andsingle count rate are measured. We designed the quality assurance (QA) setup to emulate the real MUID
operation in experiment.
The frame of panel and mid-plane are assembled ona flipper table. A double-sided tape sticks first two
tubes together with 5 mm staggering. Then the pairof tubes is stuck to the mid-plane. This procedure is

172

continued until the assembly side of the mid-plane isfilled with tubes. Next, the Gas tubing, HV supply andreadout electronics are connected. The copper sheet
for shielding is placed on the top of the tubes covering
the whole area. The Al cover-plates are anchored to
the frame for screening. Once the front side of thepanel is completed, the single count rate from cosmic
ray is measured to check the integrity of the assembled
layer.
The panel on the flipper table is set vertically withthe tabletop that serves as a strong back of the panel.
It is done so only when we can handle the panel byitself not worrying about the sagging of the mid-plane.
The panel is detached from the table at this point andflipped sidewise. Now the completed side faces to thetable. The panel is anchored to the table again andlay down flat. The backside of the panel is completed
in the same manner described above.
The small panel can be transferred horizontally withanother simple support structure to the storage placein the same factory. They are packed in well-sealed
plastic bags, which protect the panels from humid air,and shipped by sea.
All of the small panels are shipped to the BNL
MUID factory and they are tested with cosmic ray before the installation in the experimental hall.
All the small and large panels are transported fromthe BNL MUID factory with a removable strong backflat on a trailer to the experimental hall. Once a panel
and the strong back arrive in the experimental hall,
they are lifted by the main crane and set vertically.
The strong back is set on a stand inside the hall. Thenthe crane is hooked to the panel again, and the panel isdetached from the strong back. The panel is positionedby the crane and slid into a steel plate's gap from theside. 10 steel plates [13 m(H) x 10 (m) (V)] are alreadyinstalled in the experimental hall 5 in the south and 5
in the north which consists 10 gaps in total. We plan tofill those gaps with 60 panels by the end of September
1998.
References
1) H. En'yo et al.: RIKEN Accel. Prog. Rep. 30, 34 (1997).
2) Y. Mao et al.: RIKEN Accel. Prog. Rep. 30, 36 (1997).

RIKEN Accel. Prog. Rep. 31 (1998)

Design of Proton Polarimeter for AGS-E925
H. En'yo, Y. Goto, N. Hayashi, T. Ichihara, Y. Nakada, N. Saito,
H. Sakai, H. Sato, H. Okamura, and T. Wakasa
The acceleration of the polarized proton beam up to
250 Ge V / c is one of the important parts of the RIKEN
RBIC/Spin project. I) For the operation of the accelerator and to extract the physics results an appropriate
polarimeter is required. The currently designed polarimeter utilizes asymmetries for inclusive pion production in forward region in pp or p- N collision.
The experiment AGS (Alternating Gradient Synchrotron) E925 2 ) plans to measure those asymmetriesof the charged pion production in ptp or pt-Carbon
reaction at 23 GeV /e which is AGS-to-RHIC injection
momentum, where p t refers to transversely polarized
proton. Its precise data will be a base for the futurepolarimeter. The experiment consists of the pion detection part and pp elastic collision part. This reportwill concentrate on the second part where we have contributed. The elastic arm provides an accurate measurement of the extracted beam polarization for the
inclusive pion and a cross-check of the AGS internal
polarimeter. It measures the left-right cross-section
asymmetry of elastic reaction p t P ~ pp at momentum
transfer squared -t = 0.1 - 0.2 (GeV /c)2. Since theanalyzing power in this region is known within 10% of
error, the polarization of the beam can be obtained.
Figure 1 shows a double-arm telescope of the elastic arm set up. Each arm has four backward countersnamed as Bl, B2, B3 and B4 from the target andcorresponding forward counters F. (B 1 denotes B L 1
and/or BRl, and B2, B3 and B4 denote similarly.
F represents FLU EB F LD and/or F RU EB F RD). The
emission angle of recoil protons is around 78±2 degree.
Their velocity is in the range of {3 ~ 0.32 rv 0.45 andthe momentum varies 150 rv 300 MeV / c with its scattering angle. Time-of-flight (TOF) between B1 andB2, about 1 m in distance, is useful to separate recoil
protons from (3 ~ 1 particles. The wedge shaped aluminum plate compensates the angle dependence of theenergy, so that the recoil proton is stopped in the thickcounter B3; whereas the larger momentum particles,
mostly pions, hit the veto counter B4. F counters de-tect the forward proton. Beam halo veto counter (HV)and beam defined counter (BC) were also shown in the
figure.
The system had been installed and checked with theunpolarized proton beam during spring 1997. CH2
target was used for the elastic arm. Since our test wasparasitic run, the beam condition was not optimized.
The beam intensity was three orders of magnitude
lower than requested. Even with this condition, we
observed about 130 elastic events with the backwardforward coincidence. It was only about 15% of the estimated numbers, however the simulation studies were
performed and it was shown that this discrepancy was
explainable by the large beam divergence. The beam
divergence should be less than 1 mrad to maintain reasonable acceptance. Without wedge set-up, B3 ADC
and TO F have very strong correlation and it was reproduced by the simulation (Fig. 2). This is a strong
sign to show the validity of our system. Figure 3 shows
the case with the wedge setup, which was also reproduced well by the simulation.
Overall, the performance of the system was satisfactory in the limited beam condition, and the system isready for the polarized proton run.
r.)2()()

Sl()()

~(W

~90
~80

<tl

.c

.~

8()()

4()()

2()()

0

::t: 70. ). .
.-.,....

600

60
50
4()

30
20
/0

EY15GEANT~'::,,~: .,.'1.,..............

..~:;:.~

00 2 4 6 8 10 12 14 16 18 20

350

B2T(nsec)

Fig. 2. B3ADC-B2T DC scatter plots without the wedge(Bl ® B2 ® B3 trigger). Left one is experimental data
and right is a simulation result. The region indicatedby a box on the left figure includes many backgroundparticles, which was not simulated.
r.)2()() , . . - - -- -- - - - - .

~(W

<tl

S I()() ,----===------.
~90

:;CBO

oa 70

800

60
50

D08
Magnet

4()

JO
20
/0

2()()

0 350

4()()

450

500

550

BL2TDC

FLD

Fig. 1. A schematic drawing of the E925 elastic arm setup.
F counters are about 11 m from the target. DOB is aspectrometer magnet for the pion arm.

o 0 2 4 6 ~ /0 ~2/4 16 18 20
B2T(nsec)

Fig. 3. B3ADC vs B2T DC scatter plot of data (left) andthe simulation (right).
References
1) H. En'yo et al.: RIKEN Accel. Prog. Rep. 30, 33 and34 (1997).
2) K. Krueger et al.: ANL-HEP-TR-96-71 (1996).
173

6. Material Analysis

RIKEN Accel. Prog. Rep. 31 (1998)

RBS Study of Na Implanted Polystyrene
A. Nakao, Y. Suzuki, M. Iwaki, and E. Vagi
Polystyrene (PS) is one of the candidate materials
for medical use, like cell culture materials. Cell adhesion control to polystyrene surface by ion implantation
was observed. 1) One of the most important factors forcell adhesion is considered to be wettability.
We have investigated the improvement in the wettability by ion implantation with various ion species, He,
N, 0, Ne, Na, Ar, Kr, etc, and observed that the Naimplantation was most effective. The contact angle ofwater for the surface of Na-implanted PS decreases tozero with increasing Na fiuence, at low implantationenergy.2) In contrast, the PS surface implanted with
Ne, at the same implantation energy as in the case of
N a, showed the contact angle of water higher than 70
degree, independently of implantation dose and irradiation energy.
For reduction of the contact angle of water by ion
implantation, both irradiation defects by the implantation and implanted species themselves would contribute more or less. However, the result on the Ne
implantation suggests that the former contribution is
not large, because the implantation with Ne ions, having approximately the same mass as Na ions, should
produce approximately the same irradiation damage.
In addition, it was observed by the X-ray photoelectron spectroscopy (XPS) that the decrease of the contact angle of water in the Na-implanted PS is causedby the presence of the implanted Na atoms near or on
the surface of PS.3) To understand the process for Na
atoms to appear near or on the PS surface, as the firststep, Na-implanted layers of PS have been investigatedby Rutherford backscattering spectroscopy (RBS).
N a ions were implanted into PS at an energy of 50
ke V with various fiuences between 1 x 10 16 to 1 X 10 17
ions/cm2 at room temperature. RBS spectra were
measured at room temperature using a 1.5 MeV He+
beam at a scattering angle of 168 degree. Figure 1
shows RBS spectra for fiuences of 1 x 10 16 , 3 X 10 16 ,5 X 10 16 , and 1 x 10 17 ions/ cm2. Carbon, oxygen, andsodium were observed in the PS surface layers. Calibration of energy was performed by measuring standard samples, gold and copper coated PS. The surface
edges of C, 0 and Na are indicated by arrows in Fig. 1.
For the fiuence of 1 x 10 16 ions/cm 2, the depth profile
of Na atoms in the PS shows a Gausian-type distribution. With increasing fiuence, the N a atoms become
concentrated in the surface layer and the distribution
starts deviating form the Gaussian distribution. Spec-

10
~

c:

:::l

-e

~

-c

Q)

>=

4

2

0

0

0.2

0.4

0.6

0.8

Energy (MeV)

Fig. 1. RBS spectra of the PS samples implanted withvarious fluences of Na ions between 1 x 10 16 to 1 X 10 17
ions/cm 2 at the implantation energy of 50 keY at room
temperature.
tra for oxygen are found to have two peaks. The peakin the deep layer is considered to have originated fromthe 0 atoms implanted accidentally during the Na implantation.
From these results, the process to give rise to achange in the depth distribution of N a and 0 atoms
might be considered as follows: As the fluence increases, the concentration becomes so high that the N aatoms move out toward the surface to interact withoxygen in the residual gas and/or atmospheric oxygen. As a result, the Na atoms are accumulated in thesurface region together with 0 atoms. Similar behavior was observed for the Li and K atoms implanted inglassy carbon, i.e. , Li and K atoms were found to become concentrated near the surface of glassy carbon. 4 )References
1) Y. Suzuki, M. Kusakabe, J .-S. Lee, M. Kaiara, M. Iwaki,
and H. Sasabe: Nucl. Instrum. Methods Phys. Res . B
65, 142 (1992) .
2) Y. Suzuki, M. Kusakabe, and M. lwaki: Nucl. lnstrum.
Methods Phys. Res. B 80/81, 1067 (1993).
3) A. Nakao, Y. Suzuki, and M. lwaki: J. Colloid Interface
Sci. (to be published in 1998) .
4) K. Takahashi, K. Yoshida, and M. Iwaki: Electrochimi.
Acta. 35, 1279 (1990).

175

RIKEN Accel. Prog. Rep. 31 (1998)

Chemical State Analysis of Third Period Elements in
Atmospheric Air by High-Resolution PIXE
K. Maeda, K. Hasegawa,*1 A. Tonomura, M. Maeda,*2 and H. Hamanaka*1
Fine structures of X-ray emission spectra reflect
the chemical environments of atoms in target materials. Particle induced X-ray emission (PIXE) measurements in non-vacuum, especially in air, is quite
suitable for biological, environmental and archaeological substances. We have developed a compact crystal
spectrometer system for non-vacuum high-resolution
PIXE analysis. 1) The system has been designed to detect the low-energy X-rays of less than 3 keY effectively. This is because the third period elements (suchas Na, Mg, AI, ... ) with K X-ray energies of 1-3 keYplay important roles in biological, environmental andarchaeological substances. In the present report wedemonstrate the ability of the system for in situ chemical state analysis of the third period elements, measuring K X-ray spectra of AI, Si, P and S in various
compounds. 2)
We adopted a multichannel-type crystal spectrometer combined with a position-sensitive proportionalcounter. A target sample was placed in the air andbombarded with a 2.1 MeV proton beam of 3 mmdiameter. Measured samples were an Al metal, a sintered alumina, a silicon crystal (c-Si), a fused quartz(Si02), powders of chemicals of SiC, Si3N 4, SiO, BP,
CaHP0 4·2H 20, Na2S04 and Na2S03, soils of Flaming Mountains in China, powders of diatom frustules, ajewel of opal, and a fragment of a fossil wood. The sample was set on an aluminum target holder and the proton beam current was monitored from the Al holder.
For insulator samples, a small bridge made from a carbon sheet was put between the Al holder and the target
surface near « 5 mm) the beam spot.
Examples of measured spectra are shown in Figs. 1
and 2. There is some uncertainty in the channel number of each spectrum depending on the target positioning. The maximum value was estimated to amount to±2 channels corresponding to ±0.04° in e. Chemical
shifts of the main peak (denoted by K (31) of K {3 spectra are beyond this uncertainty.
The low-energy satellite K {3' is caused by molecularorbital splittings due to formation of chemical bonds.
The energy difference between the K {3' and K {31 indicates the partner atom of the X-ray emitter. The Si
K {3rSi K {3' energy differences are about 14, 11 and
9 eV for the Si-O compounds, Si3N4 and SiC, respectively. In the spectrum of SiO the K {31 line consists of
two peaks. The higher-energy peak is attributed to SiD
atoms and the lower-energy one is attributed to Si4+
atoms.
In analogy to the Si K {3 spectra of the Si-O compounds, the K {3' satellite is again observed in the
S K {3 spectra of Na2S04 and Na2S03 at the energy
region 14 eV lower than the K {31 line. The high-energy
*1
*2

176

College of Engineering, Hosei University
Tokyo University of Fisheries

X.ray energy (eV)

:j

c·Si

o-.c

\

I,sr!

SiC

i': ~I~~

angle of diffraction (8" )angle 01 diUraclton (e ·)Fig. 1. Si K (3 spectra measured with an InS b (111) crystal.
Q is the accumulated beam charge.
X·ray energy (eV)

2450

2460

2470

2480

angle 01 dltfr.ction (If)

Fig. 2. S K(3 spectra measured with a NaCI (200) crystal.
Q is the accumulated beam charge.
shoulder (K (3") of the S K (31 line is useful to distinguish S in SO~- from S in SO~-. As an attempt ofpractical application of the system, we measured theS K X-ray spectra for a fossil wood of 400,000 years
old,3) which contained 2-5% of S. As shown in Fig. 2,
the K {3' sate!lite of indicatin:.r- t~e presence of o~ygencompounds lIke SO~- or S03 IS not detected III the
S K {3 spectrum of the fossil wood. The K {3 spectrum
rather resembles that of sulfides (S2+). The S atoms in
the fossil wood, at least in its surface layer, seem to bepresent as sulfide but not as sulfate nor sulfite. Thus,
the chemical environment of the minor element, S, in asmall area (rv 10 mm 2 ) was successfully determined byusing the newly developed in-air high-resolution PIXE
system.
References
1) K. Maeda et al.: Nucl. lnstrum. Methods Phys. Res. B,
in press.
2) K. Maeda, K. Hasegawa, H. Hamanaka, and M. Maeda:
Nucl. lnstrum. Methods Phys. Res. B, in press.
3) N. Kagemori: J. Geosci. Osaka City Univ. 16, 11 (1973).

RIKEN Accel. Prog. Rep. 31 (1998)

Improvement in the Detection Limits of ERDA
Using a Time-of-Flight Detection
W. Hong, S. Hayakawa,* K. Maeda, S. Fukuda, K. Kimura, Y. Gohshi,* and 1. Tanihata
An advantage of the Time-Of-Flight Elastic Recoil
Detection Analysis (TOF-ERDA) is the ability of detection of trace elements with extremely small background. If the large background peak of a heavy matrix in the energy spectrum was eliminated using a
TOF-energy plot, the detection limit of light element
is much lower than that obtained by the conventional
ERDA.
A detection limit (L D ) is defined byl)

LD = 2.71 + 4.65VYB-

N[col cosa LD -aob1]nQ

D,

(2)

(a)

250

E 200
::::I

8 150
100
50
10

15

20

energy (MeV)
120 .--------;;-----------,

(b)

100

80

§ 60

(1)

where N is the number of the sample molecules perunit volume, [col the stopping cross section factor of
the sample, ao the differential cross section of target
atom at the sample surface, b the energy corresponding to one channel, 1] the detector efficiency, n the solid
angle, Q the number of the probe ions, and a the incident angle of the beam measured with respect to thenormal to the surface.
40 Ar ions accelerated to 41.5 MeV by the RIKEN
linac (RILAC) were used as probe ions. The beam
size was 2 mm</>. The distance from the collimator to
the sample was 30 cm. The incident and detector angles were 55° wit h respect to the beam direction. A
SSB (Silicon Surface Barrier) detector was employed
to measure the energy of recoil particles and to obtain a start signal. A time of flight detector was composed of two MCPs (Micro Channel Plate), and a 10
f-lg/ cm 2 carbon film was used to obtain the stop signal. More details concerning the experimental setup
are described in a previous publication. 2) A Si02 filmof 240 nm in thickness on a silicon wafer was used toevaluate the detection limits of the oxygen and silicon.
The energy spectrum of Si0 2 obtained by conventional ERDA is shown in Fig. 1(a). An oxygen peak
appears on a silicon peak, which is the background of
the oxygen peak. The separated peaks of oxygen andsilicon by TOF-ERDA are shown in Fig. 1(b). Thereis no background from the heavy element under theoxygen peak any more.
Faculty of Engineering, University of Tokyo

300

c:

at the 95% confidence level, where YB is the countof the background. To convert this detection limit in
the unit of counts to the amount of element, or inthis case the areal density, an additional considerationis necessary. The atomic density (ND ) of the target
element at the sample surface is calculated by
N

350

40
20
5

10

15

20

energy (MeV)

Fig. 1. Energy spectrum of a Si02 sample measuredby (a) conventional ERDA and (b) TOF-ERDA. The
dashed curve represents the Si peak, and the solid curve
the 0 peak. The incident particle is Ar accelerated to41.5 MeV.
The backgrounds at the surface of the oxygen andsilicon peaks were evaluated from Fig. 1 by averaging the background values of 10 channels near to thesurface channel. In Table 1, the results of a calculation using Eqs. 1 and 2 are summarized along with theexperimental conditions. There are differences in thedefinitions of detection limit used by various authors.
Therefore, the detection limit of the oxygen obtainedby the TOF-ERDA in present work is reasonable compared to the reported value of 0.3 at% by D. K. Avasthi
et al. ,3) and are valid for most applications.
Table 1. The detection limits of the oxygen and silicon ina Si0 2 sample obtained by TOF-ERDA and ERDA. Y B
is the background count of the sample surface. LD is
the detection limit in count calculated by Eq. (1). ND
is the detection limit in the atoms/cm 2 calculated by
Eq. (2). The confidence level is 95%.
Pro b e E O S a mple t)!1Q Target
cr
TOF·EROA
C o nve n t ional EROA
(M e V)(10 7 )
(10- 2 4 ) YB LO N O ( 1013 ) YB LO NO ( 10 13 )4 0 Ar 41.5

Si02

124

0
Si

4 .05
5.97

0 . 5 6 .00
1 .4 8 .21

6 .62
10 .5

31
28 . 5
1.4 8 . 2 1

31.4
10 .5

References
1) L. A. Currie: Anal. Chern. 40, 586 (1968).
2) W. Hong, S. Hayakawa, K. Maeda, S. Fukuda, M.
Yanokura, M. Aratani, K. Kimura, Y. Gohshi, and I.
Tanihata: Nucl. Instrum. Methods Phys. Res. B 124,
95 (1997) .
3) D. K. Avasthi, D. Kabiraj, A. Bhagwat, G. K. Mehta,

V. D. Vankar, and S. B. Ogale: Nucl. Instrum. Methods
Phys. Res. B 93, 480 (1994).

177

RIKEN Accel. Prog. Rep. 31 (1998)

Determination of the Mass and Depth Resolutions of TOF-ERDA
W. Hong, S. Hayakawa,* K. Maeda, S. Fukuda, K. Kimura, Y. Gohshi,* and 1. Tanihata
The most commonly used incident ions for Elastic
Recoil Detection Analysis (ERDA) applications are
low-energy He. However, the heavier projectile has
many advantages. Combinations of various projectiles
and various incident energies should be investigated inorder to determine the optimum measurement conditions. Especially, optimization of the energy resolution
of ERDA is a very important factor, because it is directly reflected to the mass resolution and to the depth
resolution.
2oNe, 40 Ar and 136Xe ions accelerated by the RILAC
were used as probes. The incident energies were 22.6
and 41.5 MeV for Ar, 20.0 MeV for Ne, and 138.1
MeV for Xe; all of them, except for 22.6 MeV 40 Ar,
were about 1 MeV jnucleon. The incident angle of thebeam and angle of the detector were both set to be
55 0 , and the beam size was 2 mm in diameter.
A silicon surface barrier (SSB) detector and a time
detector 1) which is consisting of a 10 p,gjcm 2 carbon
foil and two micro channel plates (MCPs) were employed to measure the energy and the time of flightof a recoil particle. The details about experimental
setup are in our previous publication.2) To determine
the mass resolution and the depth resolution, a Si wafer
was used as a sample.
The mass resolution of the measurement system wascalculated according toc~:) 2 = ( ~EE) 2 + (2~t) 2 + (2~1) 2(1)

where M and E are the mass and the energy of a recoil
particle, respectively; t and l are the time of flight andthe length of flight path, respectively. The last term ofEq. (1) is negligible , since the path difference is verysmall.
The recoil energy E2 before reaching the telescope is
E2 = KREO - {S} x,(dEm) =~

~E(x)/{S}.

(3)The energy and time spectra of recoil particles froma Si wafer using the projectiles Ne, Ar and Xe areshown in Figs. 1 and 2, respectively. !lE (0) and !Itof Eq. (1) for each projectile were obtained from theleading edge of these spectra. The small peak in each
spectrum is due to the contaminated carbon at the
sample surface. The incident Ne peak scattered by thematrix element, Si, appears in Figs. 1(a) and 2(a).
The depth and mass resolutions at the surface of thesample, calculated by Eqs. (1) and (3), are summaFaculty of Engineering, University of Tokyo

178

2500

§ 100

§ 1500(b) Ar
22.6 MeV

2000

8

81000

It

50

500

0
10

15

10

0

15

1000

500
(c) Ar
41.5 MeV

400

§ 300

(d) Xe800138.1 MeV

§ 600
8

8 200

400

100

200

a

0
10

15

a

20

10

20

30

40

energy(MeV}energy(MeV}

Fig. 1. Energy spectra obtained with the incident ionshaving different masses and energies.
700 .......-:-;--;-------,
600
500
400
8 300
200
100

§

o L.o..o..................................w......................"""""o 20 40 60 80 100

1400
1200
1000
§ 800
8 600
400
200

(b}Ar
22.6 MeV

a
40

20

60

500
500

400

C 400

§ 300

5u 300200(d) Xe138 MeV

8 200
100

100
O ........................................u...w............~

o

20

40

60

80

10

20

time(ns)

40

60

80

time(ns}Fig. 2. Time spectra obtained with the incident ionshaving different masses and energies.
rized along with the experiment conditions in Table 1.
Though these mass and depth resolutions were overestimated, because of the surface contamination of the
carbon, they are reasonable for most applications.

(2)

where KR is the recoil kinematic factor, Eo the incident
energy, {S} the stopping cross section factor, and x thedepth where the recoil occurred. The stopping crosssection factor {S} can be calculated using Ziegler'stables. 3) If the energy width of the particle recoiled
from depth x by a mono-energetic incident beam isregistered as !lE (x), the depth resolution is defined asrex) = ~E(x)/150

Table 1. Comparison of the near-surface mass resolutions
t:::.M and the surface-depth resolutions r(O) between
the incident energies and probes. {S} in ke V / (10 15
atoms/cm 2 ) was calculated using Ziegler's table. t:::.Mand r(O) in 10 15 atoms/cm2 were calculated using Eqs.
(1) and (3), respectively. The sample was a Si wafer.
Beam Energy Recoiled ~t(O) {S}
(MeV)
atom
(ns)
20Ne
40 Ar
136

Xe

20.0
22.6
41.5
138.1

Si
Si
Si
Si

1.3
1.1
0.9
1.0

1.89
2.18
2.43
2.86

~Em(O)

(keV)

316
470
530
766

SurfaceMassd epthresolution
resolution
~M

167
216
218
267

2.07
2.32
1.90
2.48

References
1) K. Kimura and J. Wada: Phys. Rev. B 48, 15535 (1993).
2) W. Hong et al.: Nucl. Instrum. Methods Phys. Res. B
124, 95 (1997).

3) J. F. Ziegler et al.: The Stopping and Range of Ions in
Solids (Pergamon Press, London, 1985).

IV. NUCLEAR DATARIKEN Accel. Prog. Rep. 31 (1998)

Status Report of the Nuclear Data Group
Y. Tendow, A. Yoshida, A. Hashizume, and K. Kitao
The Nuclear Data Croup has been carrying on threekinds of nuclear data activity described below since theprevious year. 1)(1) Nuclear reaction cross-section data (EXFOR)Compilation of the charged particle nuclear reaction
cross section coordinated by the IAEA Nuclear Data
Section (NDS) has been continued. Following to our
original objectives we have been collecting the reaction
cross section data important to produce the following
twenty typical radioisotopes for medical study: they
are l1C, 13N, 15 0, 18F, 28Mg, 52Fe, 67Ca, 68Ce, 74As,
77Br, 82Br, 77Kr, 81Rb, 82mRb, 111In, 123Xe, 127Xe,
123 1, 124 1, and 1251. In order to maintain the completeness of the database, we also have been collecting reaction data which had not been included in the EXFOR
master file up to the present.
In the previous year, we transmitted an EXFOR
compilation file named 'TRANS ROll'. That was oureleventh transmission to the NDS contained three entries 'R0051', 'R0052', 'R0053' with a total of 86 excitation curves. However, the data in the 'R0051' entry turned out to be already included in the EXFOR
master and consequently it was not incorporated into
it. The compilation of new entry 'R0054' and beyond
as well as an alternative new entry 'R0051' is now inprogress.
(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). After the publicationof A = 127, 129 mass chain last year,2,3) A = 120
mass-chain evaluation draft is now under the author's
review prior to the printing. Because several new dataon the high-spin states for A = 129, as well as for otherneighboring masses, are coming out after that publication, we are planning to make some partial updatings
for this mass data before long.
It is revealed that the current ENSDF coding format
requires a proper upgrading in order to accommodate
accumulating experimental data from recent advancesin high-spin state physics using in-beam spectroscopy
techniques.
(3) Nuclear Science References (NSR)
We are engaged in collecting and compiling secondary references (unpublished works such as annual
reports, conference proceedings, etc.) appeared inJapan since the previous year into the Nuclear Science

References (NSR) file format and transmitting themto the NNDC.
The compilation of 1996 annual reports has been
completed and transmitted to the NNDC. Japanese
secondary sources that were surveyed this year are as
follows (shown in code name in NSR file):
RIKEN (RIKEN Accel. Prog. Rep.),
JAERI-TV (JAERI Tandem & V.D.C. Rep.),
JAERI-TIARA (JAERI Takasaki Ion Acc. Advanced Rad. Appl.) ,INS (Inst. Nucl. Study, 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 Acc. Lab.)CYRIC (Cyclo. Radioisot. Center, Tohoku Univ.).
The long pending problem on the entry key-numberof references to accommodate the publication year beyond 2000 has been settled finally. The previously used
six-character key-number, e.g. 97Ab01 has been extended to eight characters as 1997AbOl. New data services are to be available in January, 1998 and onward
from the NNDC after replacement of the processing
programs and the NSR database rewritten incorporating the new key-numbers.
(4) Others
The Technical NRDC (Nuclear Reaction Data Centers) Meeting was held at the IAEA NDS in Vienna
on 26- 28 of May 1997. The meeting is to be held every two years between the biennial plenary meeting
named IAEA Advisory Group Meeting on the Coordination of NRDC. The Meeting mainly discussed technical aspects of construction, maintenance and dissemination of the EXFOR database. Major topics were
the on-line data services through the WWW networks
and the proper citation and reference guidelines forthe electronic databases which are apt to be updated
irregularly and/or frequently. These issues are to be
discussed and fixed at the plenary NRDC meeting next
year.
References
1) Y. Tendow, A. Yoshida, A. Hashizume, and K. Kitao:
RIKEN Accel. Prog. Rep. 30, 165 (1997).
2) K. Kitao and M. Oshima: Nucl. Data Sheets 77, 1(1996) .
3) Y. Tendow: Nucl. Data Sheets 77, 631 (1996).

179

V.

DEVELOPMENT OF ACCELERATOR FACILITIESRIKEN Accel. Prog. Rep. 31 (1998)

Progress of RI Beam Factory Project
Y. Yano, A. Goto, and T. Katayama
Within the on-going RI Beam Factory project, acascade of a K930-MeV ring cyclotron (IRC) and a
K2500-MeV superconducting ring cyclotron (SRC) will
be constructed as an energy booster for the existing
ring cyclotron (RRC). With this new cyclotron system the final energy will be increased up to morethan 100 MeV/nucleon even for very heavy ions. By
the projectile fragmentation these energetic heavyion beams are converted into the RI (radio-isotope)
beams covering the whole range of atomic masses andthe energies of several hundred MeV/nucleon. Moreover, this factory will include a next generation accelerator named the multi-use experimental storagerings (MUSES) consisting of an accumulator-cooler

ring (ACR) , a booster synchrotron ring (BSR), anddouble storage rings (DSR). The MUSES will enable
us to conduct various unique colliding experiments.
Bird's eye view of tentative layout of the new factory
project is illustrated in Fig. 1. Optimization of thesearrangements is under way.
During 1998 fiscal year, the three-year SRC construction budget for constructing six sets of superconducting sector magnets without their yokes has been
approved.
The details of the R&D work to include the design
work of each component are given in the following reports.

Existing Facility

BSA: Booster Synchrotron Aing with a
0.3 GeV electron linac to accelerate an
AI (HI) or an electron beam
DSA: Double Storage Aings forcolliding experiments of HI, AI,
photon, and electron beamsoSOmf-I--+-+----+---+------jllAC, SAC: A cascade of Aing Cyclotrons(AC's) to boost the energy of HI beams
from the AAC

ACA: Accumulator Cooler Aing to coolan AI ·(HI) beam using stochastic cooling
and/or electron cooling method

Fig. 1. Tentative layout of the designed RIKEN RI Beam Factory.

181

RIKEN Accel. Prog. Rep. 31 (1998)

Improvement of Sextupole Magnet for RIKEN 10 GHz ECRIS
M. Kidera, T. Kageyama, T. Nakagawa, J. Fujita, M. Kase, A. Goto, and Y. Yano
The 10 GHz ECRIS (Electron Cyclotron ResonanceIon Source) at RIKEN is used as the injector of AVF
Cyclotron Accelerator. I) Various heavy ions of such as
C, N, 0, and Ar, are produced by the ion source, andare supplied for various experiments. For a long-time
operation, a main problem at present is an instability
in the beam intensity.
The supply of a stable beam is very important for
better experiments. One of the main reasons of thebeam instability could be a weak radial magnetic field
generated by permanent sextupole magnet. The ECR
surface is therefore too close to the wall of the plasmachamber. As a result, the ECR surfaces are disturbed
by the collision of charged particles with the innersurface of the chamber, implying that many ions andhot-electrons are reverted to the neutral particles andthe low energy electrons, respectively. In order to improve the performance of the ECRIS we are designinga new sextupole magnet.
Cross-sectional view of the existing and new sextupole magnets are shown in Figs. 1 (a) and (b), respectively. The new sextupole magnet is made fromthe N38H permanent magnets (Shin-etsu Kagaku Co.).
Each of the magnet of 480 mm long consists of twopieces, and the direction of magnetic poles is at 36°
relative to the chamber surface. As shown in Fig. 2,
the magnetic lines of force of the sextupole magnet
were calculated by a code POISSON using B/H function of the permanent magnet. In Fig. 3, the maxi-

Fig. 2. The magnetic line of force of the new sextupole
magnet. This result was calculated by the code POISSON.

til

:s
'"

~

4

C

20

60

Chamber radius (mm)Fig. 3. The curve of the strength of the total magnetic
field. The curve amount to maximum strength at thechamber surface.

mum strength of the total magnetic field at the newchamber surface is compared with that at the existing
chamber well. The maximum strength of the new sextupole magnet is about 1.6 times that of the old one.
By the new sextupole magnet, the confining magnetic
field should be improved , and we expect that the stability of the plasma improves.
(a)

(b)

References
Fig. 1. Cross-sectional view of an existing sextupole magnet (a) and the new sextupole magnet (b).

182

1) T. Nakagawa, T. Kageyama, M. Kase, A. Got o, and Y.
Yano: Jpn. J. Appl. Phys. 32, 1335 (1993).

RIKEN Accel. Prog. Rep. 31 (1998)

Improvements of Low RF Power System in RIKEN 10 GHz ECRIS
J. Fujita, T. Kageyama, and T. Nakagawa
Some electric and mechanical troubles arose in 10
GHz ECRIS RF system frequently. They resulted
mainly from poor mechanism of a mechanical rotaryattenuator and from lack of the gain stability against
temperature in a GaAs FET amplifier. These components, which had been used before the klystron amplifier, were replaced by new ones in April 1997. Block

diagrams of the previous and new systems are shownin Fig. 1. The RF inputs and outputs in the old system were all made through WRJ-I0 type rectangularwave guides (shown by heavy lines in Fig. 1), but inthe new one they were replaced by SMA type coaxial
connectors so that arrangement and availability of thecomponents are easy.

(a)
Gunn

Mechanicalrotarydiode
Oscillator

GaAsFET

to
Klystron
input

AmplifierAttenuator

8(b )Dielectric

VariablePIN

Resonator

RotaryDiode

Oscillator

Atten.

Atten.

36 dB
AmplifierCoax. toto

Rectang.
Adapter

Klystron
input

Current
Control

Fig. 1. Comparison between previous and new systems. (a) a previous system. (b) a new system.

The major changes are as follows.
(a) A Gunn Diode Oscillator (GDO) was replaced
by a Dielectric Resonator Oscillator (DRO).
Oscillating frequency of the DRO has superior temperature stability (20 ppm per centigrade) to that of
the GDO.

(b) A mechanical rotary attenuator was replaced by
a PIN diode attenuator.
The PIN diode attenuator can vary the output powerby changing an insertion loss from 3.25 dB to 30 dB . In
addition to this PIN type, there is another attenuator
which is a variable rotary attenuator and can protect
12 bitsto
PIN DiodeUP

12 bits
UP/DOWNCounter

Push SW
relay out
DOWN

A.C.
100V

@

D.C.
Source+15V
GND

UP inhibit-15v
DOWN inhibit

Fig. 2. A control circuit of a PIN diode attenuator.
183

input of the amplifier from being exposed to an excessive power due to troubles in the DRO or in the PIN
diode attenuator.
(c) A GaAs FET amplifier was replaced by a solidstate 36 dB amplifier.
A new amplifier is half in size, works with a single+15 volt-de power supply, and keeps a stable operation up to 5 watts under a considerable temperature
variation.
A directional coupler with coupling value of 20 dB
and insertion loss less than 0.55 dB was newly placed
after the amplifier in order to observe input power of
the klystron. In the final stage, an adapter changing
from the SMA coaxial connector to WRJ-I0 rectangular wave guide was used to fit the input of the klystron.

184

The PIN diode attenuator is controlled by varying
the conducting current from 0 to 20 rnA which is fed,
through a serial resistor, by a 12 bit DA converter. A
block diagram of the current control circuit is shownin Fig. 2. The input of the DA converter is connectedto the outputs of three 4-bit binary UP/DOWN counters. The three counters are put in sereis and countpulses with repetition rate of 20 Hz through AND gates
opened by UP/DOWN switches on a control desk.
Lower and upper limits of the attenuator are determined, not by analog levels of a voltage signal but bycomparisons of the digital parallel 11 or 12 bit outputsof the counters.
So far the new system has not encountered a fatal
trouble and is working well.

RIKEN Accel. Prog. Rep. 31 (1998)

Electron Beams Indeed Lower the Ion-Trapping Potential Barrier
via Sheaths to Enhance the HCI Component in an ECRIS:
Analytical Proof
M. Niimura, A. Goto, and Y. Yano
Based on theories of the collisionless sheath andmobility-limited diffusion, it was possible to prove analytically that the electron (e-) beams, prepared internally or externally and injected into an ECR ion
source (ECRI8) plasma, can indeed lower the heightof the ion-trapping potential barrier (¢i) locally, thus
prompting the highly charged ions (HCI) to cross overthe ¢i and contribute the extracted ion-beam current[See, inset of Fig. 1] The analytical results agree wellwith experimental 1) results. Present paper has confirmed that it is the current, not the density2) nor theenergy, of e-beam that can enhance the HCI component. No direct interaction is needed 3 ) between the
hot-to-warm electrons inside the ECRI8 nucleus andthe injected e-beam itself, as shown in the upper figure
in Fig. 1. No conductive disk is needed: high workfunction material4 ) as well as an insulator can fulfill
the mission since the electric bias is created by the effect of sheath as shown in the lower figure of Fig. 1.
These findings are vital for improvement of the ECRIS
performance.

with the uniform ion density nj = n s , and a potential difference ¢:::;::: Vs - V (~O) with which electrons are confined as ne = ns exp( -e¢/kTe); wherens (:::;:::0. 61no) and Vs are the particle density andpotential at the sheath edge (z = zs). Then, thespace charge density is p : :;: : e(ni - ne) ~ co¢/ AB, defining AB : :;: : (cokTe/nse2)1/2 :::;::: 1.28AeD with usual AeD : :;: :(cokTe/noe2)1/2 expressed by the density at the preseath (z = zps) where ne = EZini = no. Then, thePoisson equation 8 2V /8z 2 = -p/co is in the form:(82/8z 2 - Ai3 2)V = -Vs/A~, which gives V(z) =-(Vs - Vc) exp( -z/ AB) + Vs under the boundary conditions V = Vf and Vs at z = 0 and 00, respectively.
The self-consistent potential distribution is:V(z) = [l-exp(~~)]vs (ifVf=O, ioO<z~zs)(1)This Vs in Eq. (1) is lowered by the presence of an ebeam current (jeb), as will be seen later. On the other
hand, in the next domain Zs ~ Z ~ ZECR the density
obeys Boltzmann law. Therefore, the potential distribution is:
kTe °ECR
V(z) = VECR - 1 0 - - (zs ~ z ~ zECR)
(2)
e

Oe(Z)

This V ECR too is lowered by jeb as will be seen soon.
It is well known that ion saturation current density (j+) and the random electron current density (j _ ),both directing towards the plate, are given, respectively, by
i+ "en,vB = o.61enoVkT. ,d~I.O.b9Ss-..!...
n e :.

_(Veth)
J- == -eo w -"r.c.c:ot(1*fi-- ·1)

4_SboaIh~~.,4- . ..::.:';.::~.'"

(3)

ffii

(Iro"",lo,.1-O)

nCI-Trap"'" P.....tlal-W.U

Normaliud As.iaJ. DistllDC't., z' or zI >".

Fig. 1. Schematic diagram showing the internallyclosed-loop of e-beams (floating-disk and wall-coating
schemes) whose jeb can lower the height of <Pi.
Consider that an end of the ECRIS plasma is terminated by an isolated plate, such as a disk and apiece of wall, orthogonally to the mirror magnetic
field (MMF) B z. Then, it is not difficult to explainthat the ions will be uniformly distributed within theelectron Debye length (AeD), while the electrons areless distributed for the position closer to the plate(z = 0). This means that a charge-separation electricfield Es/ / is created in the negative-z direction (pointing the plate) within the domain 0 ~ z ~ Zs :::;::: AeD
called sheath. Since - J Es/ /dz = V (z), an increasing axial electrostatic potential is generated over the
sheath. Assume such a wall (or ion) sheath filled(Veth)= -eo o -

4

-

exp

-e(Vs - Vr)
kTe

( 4)

where (Veth):::;::: (8kTe/1l"me)1/2.
Now, if a portion of the above j _ is re-directed away from theplate, forming an e-beam with density jeb : :;: : -eneb Ve'
Then, the net current density arriving the wall is
j- - jeb = (1- S)j_, where 8:::;::: jeb/j- (~1). Namely,when jeb -# 0, the right hand side of Eq. (4)should be divided by (1-8) for the new j_.
Then, the isolated-plate condition: j+ + j_ = 0 gives
Vs - Vf = (kTe/2e)[ln(0.43mi/me) + 2In(1- 8)], orkTe
Vs - Vf = -[10177+ 1n(1 - 8)) (for argon)e(5)

The term, In(l - S), is negative, thereby decreasing the value of Vs - Vf down to null if S = 1(me/0.43 mi)1/2 = 0.995 for the case of argon. [See,Fig. 2]. When S « 1, we have In(l - S) ~ -S, andtherefore Vs-Vf decreases linearly with S. Substitutionof Vs in Eq. (5) into Eq. (1) yields:
V(z) = k: e [l-exp(~~)] ·10[177(1 -8)) (ifVr=O)(6)This equation tells that indeed the potential is lowered
as S or jeb increases in the domain 0 < Z ~ Zs.
185

Since D.¢i S jeb V~(:s when jeb is the spacecharge limited electron-beam current. Eq. (12) giveslib(S) = lib(O)exp[Const ·jeb) = Iib(O)exp[Const . V~(:s) (13)Figure 3 shows a good agreement of experimental databy the expressions of the type of Eq. (13): for both
lib and iib. The space-charge limited ion-beam current
density, which represents the discharge current of e-gun
circuit, is theoretically jib = 7.08 and 1.12 mA/cm 2for H+ and Ar+ ions, respectively, for the e-gun withd = 2 mm and s = 0.57 cm 2 at V bias = 300V. This
corresponds, the space-charge limited electron-beamcurrent, jeb = (mi/me)I/2jib = 303 mA/cm 2. Indeed,
iib(mA) = 7.84 x 10- 4 V~(:s in Fig. 3 can describe theexperimental e-gun received ion-beam data quite well.
As for the saturation current, Eq. (3) gives
j+(A/m2) = 1.51 x 1O-16 no (Te)1/2 (for Ar+ l l )(14)
in MKS units. In order to obtain T e , we use Eq.
(5) under S = 1 or Vs - V f = (Te/2e)ln(0.43mi/me)
to be compared with another experimental 1) result:
Vf = -14 and -21V were observed at 400 and 800W
of rf power. This experiment was done with N+
and V f was measured in reference to V s = 0, sothat V f = -4.65T e theoretically. This gives T e = 3.0
and 4.5 eV as the 1st stage T e' Substitution of
no = 1.61 x 1011 cm- 3 (neutrals at Po = 5p,Torr) and
Te = 4.5 eV in to Eq. (14) gives 1+ = 2.9 mA, whichis in good agreement with the experimental saturation
current (1+ = 3.0 mA) observable in Fig. 3.
I'V

1
z
~

3

!

,

~

i 1r-~~~~__r -r
0.2

0.4

0.6

0,8

NonoaJIJed ....... c - t DtulIJ. S or ',." .

Fig. 2. Logarithmic and linear decays of the electron-trapping electrostatic potentials as a function of S.
Because the externally-fed rf-power is continually producing charged particles at the ECR-zone,
there exists a positive density gradient (Vn) toConsider that jeb with denwards the center.
sity neb is injected into such a mobility limited domain. Since e-beams are spatially uniform, Vneb = O.
Then, we have fe = -DeVne - p,eneE(l - S), where
However, jeD == -eDa Vne
S == feb/lfel = jeb/UeD I.
(from Fick's law), which ought to be j_ from the continuity of current at Zs' Hence, S == jebfj- as before. On
the other hand fi = - DiVni + P,ini E . Since P,e » P,i,
De > > D i , and ne ~ ni in Zs :S z :S ZECR, the conditionf e = fi at z = Zs determines the magnitude of ambipolar electric field (Eamb). Integration of the Eamb fromz = Zs to ZECR yields:
kTe
VECR - Vs = (1 - S) I nnECR
-(7)
e
ns
Figure 2 shows Eq. (7) for the case of nEcR/n s = 176
for matching with Eq. (5) at S = O. Substituting VECR
of Eq. (7) into Eq. (2), we obtainkTe ne(z)V(z) = (1 - S) - In-- + Vs(zs)(8)
ensSince the ambipolar diffusion equation an/at =D AV 2 n has a trigonometric solution, Eq. (8) becomes,
if nEcR/n e = 2:
V(z') = (1 - s/:e In [2 cos ~ (:: - 1)] + Vs(z~ = 5)(9)where z' == z/ AB. V(z) is plotted in Fig. 1 with parameter S.
Change in the sheath potential with and without jebcorresponds to a lowering of the ion-trapping potential barrier ¢i by D.¢. Namely, D.¢i = (Vs - Vr)s=o(Vs - Vf)s=lO. Using Eq. (5), we have
kTe
kTe
(10)
l:l.<Pi = - -e- In (1 - S) ~ S-e-(S ~ 0)
Similarly, Eq. (7) gives
kTe nECR(11 )l:l.<Pi = S-In-- == s· (VECR - Vs)s=oens
Now the ECRIS extracted ion beam current(lib) is given by lib == ZieSendfend = ZievBnz(O)·exp[-Zie¢i/kTd, where VB = (kTe/mi)I/2. As the ¢iis lowered to ¢i - D.¢i, the magnitude of lib enhancesby the factor 7] == Iib(S)/Iib(O) = exp[ZieD.¢i/kTdFrom Eqs. (10) or (11) we obtain:
ECR ] (s = jJ~eb)T) == iib (S) = exp [ZiS Te In n(12)lib(O)
Ti
ns
186

I'V

I'V

:,...,J. .•.
. . . . ··(·-:.tu~::-:.::::z~j '"-"'l"-'J
'

:;:-

.

I ............. I

10

..:.

(11A)-8.~7.XPI2.9SXIO·'i ,(rnA)] I

.

j

::;.

I

I

I.O!

~

0.1

o

50

!.
10 11

100

150
200
250
300
IIIu VoItqe, V_ (V olt )

350

0. 1
400

Fig. 3. ECRIS extracted ion-beam current (tb) and e-gun
received ion-beam current (iib) as a function of Vbias,
showing a good agreement of the present theory [dottedline] with experimental l ) results [symbols].
This concludes that the lib in Fig. 3 is saturated. prematurely, because the iib (proportional to jeb) has
saturated; not because D.¢i ¢i has reached. Thereis thus room of improvement for the e-gun. As obvious from Eq. (14) we need to raise the Te of cathodeplasma in order to increase j+ or the magnitude of jeb'
Alternatively, a high-pressure light-mi gas (e.g., H 2) isuseful for the 1st stage by filling it independently fromthe 2nd stage.
I'V

References
1) T. Nakagawa et al.: JJAP 32, L1335 (1993).
2) M. Niimura et al.: RIKEN Accel. Prog. Rep. 28, 150(1995).
3) Z. Q. Xie: private communication.
4) S. Biri: private communication.

RIKEN Accel. Prog. Rep. 31 (1998)

RIKEN Duoplasmatron Ion Source: The Operating Principles
Compared with ECRIS, and the Direction for Future
M. Niimura, T. Kageyama, K. lkegami, M. Nagase, A. Goto, and Y. Yano
In order to identify the operating principles andto determine the future direction of the RIKEN duoplasmatron ion source (DPIS), the experimentally observed data were rationally analyzed. Present reportintroduces some of the analysis performed against thefollowing two subjects. [i) Linear scaling of the extracted ion-beam current (lib) with respect to the gas
discharge current (ld). [ii) Solenoidal magnetic field(Bz) dependence of the lib curve which depicts a peakat a specific field strength. This study has found thefollowing principles actually operating in our DPIS.
They are: formation of a double layer (DL) at theentrance of the intermediate electrode (IE); establishment of the sheath stability criterion (SSC) across theDL; acceleration and focusing of an electron (e-) beam
by a potential jump of DL, free-fall ions determining
the size of lib; and ion-beam transport governed by
the composite brightness (Bn). As a result, we weresuccessful to obtain: a correct scaling law of lib (thepublished formula was found to contain an error); a
useful expression to predict the optimal field (B opt ) to
maximize Bn or lib; and an advanced model the classical DPIS should evolve for future.
After its advent a quarter century ago, a variety of
DPISs were extensively used, before ECRIS, as injectors for RFQs, linacs, cyclotrons, and synchrotrons.
Recently, this device found new ways of use as a highcurrent e-gun,l) and as an intermittent substitute for
ECRIS at the time for light ions. 2) Further, DPIS
seems quite hopeful as a Cs-free negative ion (e.g., 9
rnA of H-) source,3) and even as a metal ion source. 4 )As for [i), the typical data are already presented as
Fig. 4 of Ref. 2. As the physics behind we suspect the
SSC. As schematically illustrated in Fig. 1(a), an IE
in the mid of a plasma diode causes a stagnation andsubsequent depletion of electrons due to the change inits flow velocity (directing left to right in Fig. 1) at
its entrance and subsequent canal, respectively. As aresult, the electron and ion space charge layers are created. Such two sheaths are called double layer. [Fig.
1 (c )-( e )]. These space charges induce an electrostatic
potential ¢(z) via Poisson equation [Fig. l(f)]. Electrons at the sheath edge (K) of cathode plasma andthe ions at the sheath edge (A) of anode plasma fall
into this potential-well, ¢(z), gaining the same energye¢. We therefore have: 5 )
1

2

1

2

2mve = 2Mvj

== e¢

(1)

o¢/oz

Further, if ¢( z) satisfies== - E = 0 at both
K and A, the momentum-transfer equation of plasma,
njmj[(dvddt+(vj·\7)Vj) = nj~(E+vjxB) - \7Pj,
tells that both particles (j = e, i) will have the same
momentum flux:dYedVj
nes (K)meve dz = njs (A)mjvj dz (\7pe = \7pj)(2)Equation (1) and integration of Eq. (2) by z yield the
SSC:
(3)

(a)

(b)

(c)

(d)

(e)

(f)

Fig. 1. Explanation of the DL and SSC, controlling DPIS .
This is a constraint for the densities at K and A.
Under the free-fall model of the ions at a positive potential edge, the extractable lib is givenby the ion saturation current density j+ == enis VB ==0.61enio(kTeo/M)1/2. Obviously, j+ is only a function of nio and Teo at the center of anode plasma.
[Fig. 1(b)). Without a particle loss, nio = nis(A) andj+ = ji = niovi· Under the SSC condition given by
Eq. (3),
jj _ Zjnjs(A)vj _ ~=jebnes(K)ve
M

(

_ )
Zj-1

(4)

This means j+ = ji = jeb(m/M)1/2, where jeb is thee-beam current density crossing DL. However, someof ions are lost into IE by ,== ni(IE)/nio = 15
30%.6) Then new values are: n~s(A) = (1 - ,)nio, andj~ == n~s(A)evi = (1-,)nioevi = (1 -,)ji. Therefore,
under a loss, j+ = j~ = (1 - ,)jeb(m/M)1/2. This
gives, since j+ == lib/7rd2 and jeb == Id/7rD2, the expected linear scaling law of lib against ld:
f'V

lib = ld(~) 2 ~ (1 - "y)(5)This formula is more logical than the published one 6)
which gives an unrealistic infinite lib at , = 0 and an
unrealistic finite lib even at , = 1. If, = 1, lib = 0
since j~ = O.
As for [ii], a typical data is shown by histograms in
Fig. 2. These lib were measured downstream of the extraction electrodes with a Faraday cup (FC) by varying
B z. A beam current transported downstream and detected by a FC of aperture S is not given by I = j+S,
but I = BSO; where Band 0 are the brightness of ion
source and the solid angle of detector seen from the ion
source, respectively. Dimension of B ought to be thecurrent density per unit solid angle, so that one can
187

15

E . 10~N

05
1

Solenoidal MalDet C u r~nt, I. [AI20

Fig. 2. Histogram of lib and its theoretical bestfit by Eq. (12) .

40

60

80 100 .120
z [mmJ

Fig. 3. Flux and Bz(z) of DPIS computed by Poisson code.
7

define B by a product of transverse emittances, f xf y : )B (A/m 2 rad 2) = l/7r 2(ExEy).
When the beam has its divergence angle (X at x on
the horizontal plane, the definition of Ex can write:
ex == ~JQ(x)dx == ..2.--J JPxdx ~ _l- J JPxdx
(6)
7r
7rP
7rP z
Since this emittance decreases as the momentum
P z ('" P) of particles increases by acceleration, Eq. (6)is normalize by multiplying the ,{3 == (3/(1 - (32)1/2
which is proportional to P z (== ,(3mioc) if mio is the ion
rest mass. Then,
exn == 'Y/3ex = ..2.!!...-J JdPxdx = _l- J JdPxdx. (7)7rP z
7rmioCThe rms emittance of Exn multiplied by 7r is given by
7rE~r::s == 7r.J(E~n) == _4- .J{x2)(P~) - (xP~)(8)
mioc
Using the Lagrangian mechanics, P x == Px - qAx =Px - (qBzy /2) and ..f(X.)I = ..f(Y)2 = R/2, Eq. (8) canbe expressed as 8 )I~>I I'It~·

)2

R
kTl
(9)
- + (Wic-mioc24cwhere R is the beam radius and Wic == qBy/mio. Equation (9) has a form of composite transverse energies ofions:
kTi + O.5mio v 2(10)(R = 2V2rLl
mio c2rms (m rad) == 2R
7rExn

Defining f.l, == mio/mpo, Eq. (10) can be written numerically:R2 (Z~R2B2(Gauss))(E~r::S)2 = 2.53 x 10- 10 ~ 16.8Tj (eV) +I:

When the beam's transverse motion is independent
from the axial motion, the 4-D phase space volume
is constant from Liouville theorem. Then, J J J J
dPxdPydxdy = (1/2)(J J dP x dx)2, and the normalized
brightness can be written by using the relationship ofEq. (7) as
21
Bn ==
I
(11)
7re
2(mi~c2)2 (J JdPxdX) 2 ( xn)2
Using the E~r::s to count 86.5% of the beam current
I = 7rR2qnisuB, we have the rms composite brightness:(_
21
O.57rqnjuB_ aB zBrms =- - - 12)n - (7rErms)2kT .
(w.
R)2 - b + cB2
xn
miO~2 + fc
zHere, nis '" B z (since D '" B;-O.5 from adiabaticity)
was assumed. Experimental data can be fitted wellby Eq. (12) as shown by a solid curve in Fig. 2.
Notice that lib'" Bn and lB '" Bz in Fig. 2. Obviously, Eq. (12) gives a maximum at B opt = (b/ C)1/2= 4(miokTi)1/2/qR. Namely, one can predict B opt by

188~r==~";;'-H VG ND-=--=- (; ND

Fig. 4. ECR1S-DPIS comparison and a future DP1S with MPC.
Bopt = 4.10 ~ZjR ()m(Gauss)(13)

For our case of He+ 1, Eq. (13) gives B opt = 1.6 kG if
Ti = 1 eV. Figure 3 indicates that the Bz strength
peaks at the anode plasma, and is widely adjustableby changing materials of the magnet pole pieces.
As Figs. 4(a) and 4(b) explain, the ECRlS plasma
is generated, heated, and ionized by an rf source while
assisted by an e-beam for extraction; whereas the DPIS
plasma is generated, heated, and ionized all by an ebeam. Such comparative study has prompted us to the
future DPIS: an advanced DPlS, operating with theCW e-beam produced by a microwave plasma cathode(MPC) e-gun 1) as shown in Fig. 4(c). This will solve
the unique problem of DPIS: longevity of cathode.
References
1) Y. Matsubara et al.: Rev. Sci. Instrum. 61, 541 (1990); M.
E. Abdelaziz: Rev. Sci. Instrum. 61, 457 (1990); B. H. Sun
et al.: Rev. Sci. Instrum. 63, 2598 (1992) .
2) M. Niimura et al.: RIKEN Accel. Prog. Rep. 30, 169 (1997).
3) Th. Sluyters: Nucl. Instrum. Methods 113, 299 (1973).
4) K. Langbein: Rev. Sci. Instrum. 61, 330 (1990).
5) J. E. Allen: PlasmaPhys. Contr. Fusion 27,1343 (1985).
6) C. Lejeune: Nucl. Instrum. Methods 116, 429 (1974).
7) P. Spadtke: Rev. Sci. Instrum. 63, 2647 (1992).
8) Y. Batygin et al.: JAERI-Conf. 95-021, 353 (1995).

RIKEN Accel. Prog. Rep. 31 (1998)

Warm-Electron Heating Mechanism in the Core of ECRIS
Nucleus, and Relevant Diagnostic System
M. Niimura, A. Goto, and Y. Yano
The free-electron temperature (T e) in ECRIS plasmas is enigmatic: a "hot electron" temperature (Teh)to exceed 10 ke V is routinely measured under the
X-ray spectroscopy, but a "warm electron" temperature (T ew ) is theoretically good enough to explain
the charge state distribution (CSD) of extracted ionbeam currents. For an instance, Fig. 1 (a) shows experimentally observed CSDs with typical ECRIS (LBNL
6.3 GRz and RIKEN 10 GRz) devices. The theoretical T e agreeable with these data is T ew = 500-1000
eV, under a low RF power (/"VIOO W) input, as envisaged from the theoretical CSD of Fig. 1 (b) which are
obtained by solving a set of 18-simulta!!~Q:Us rate equations under the condition ne'Tj = 10 10 sec cm- 3 with
Maxwellian Teas a parameter. 1 )trYTheoreticaICharacStak:Diltribulionwhcrlnctl-IOlOlcm' l secl

(b)

j

~

10

a

'

.;

(l. 1

!

f .,
CI

0.01

O.()L!:--.~---:--~-----!;;IO~----!;----------!
Cb_r'lf: SlaIt«:, q (NIDI

Fig.

1.

Cba,..~ SUik, q[NIDI

Experimental (a) and theoretical (b) CSD of

ECRIS.

There is an attempt to measure T ew' However, thediagnostics based on the endloss electrons 2 ) was obviously unable to measure T ew of the confined electrons.
Here, we propose a simple diagnostic method adequate
to measure T ew of the confined electrons, and present
a new method to estimate the magnitude and timehistory of T ew .
The new method is based on the field annihilation
heating (FAR). In order to understand the concept of
FAR, consider a plasma cylinder with a hollow of radius R through which an external magnetic field Bz isapplied. Case I: Time-varying B z (or 8B z/8t i- 0)
is externally given. Then, the Maxwell equation,-8B z/8t = \7 x E, and Stokes' theorem can show thatan azimuthal current (jf}) is induced in the plasma ofrectangular cross-section:.
JO

R 8B z= E.L/T] = - 2T] at'(1)

where 7] is the perpendicular resistivity of plasma. Because jf} of Eq. (1) is predominantly of electrons, theplasma electrons are Joule heated by the rate:
2j oT] =

R2 (8Bz)2
4'"
at [W /m 31

FAH is an inverse process of this betatron plasma
heating, as seen for the Case II: Steady B zo (or8B zo /8t = 0) and jf} are externally given. Assume
that the jf} is a diamagnetic current (in the negative
B-direction) which will force to annihilate the B zo of
mirror magnetic field (MMF). Then, another Maxwell
equation, J.Lojo = (\7 x B)o = -8B z/8r, tells that new
fields are generated both inside and outside of the current sheet as much as
Bz = -I-to

1'f~R/2.

..6.R

Jodr = ±l-toJ0o2l-toIo= ±2l'(3)

where .6.R is the scale length of jo or of B z, l is theheight of hollow cylinder, and If) = I.6.Rjf} ' This
Bz of Eq. (3) is in the negative-z direction opposed
to B zo , thereby annihilating B zo in the core plasma
by the amount equal to IBzl. Notice that the magnetic field decreases inside of the core plasma and increases outside of the mirror coil, but stays constantin-between. (Fig. 2). Therefore, a diamagnetic loop
wound around the discharge chamber can induce thevoltage Vf} = -S(8IBzl/at).
The axial field, Bz(O, t), decreases from Bzo withtime as the more IBz(O, t)1 arrives on the axis of
the core plasma. With the Ohm's law, jf} :::::: E.l./7],
two Maxwell equations yield the field diffusion equation: 8B z/8t = -(TJ/J.Lo)"V x (\7 x B z) = (7]/J.Lo)\7;Bz'
Technique of the separation of variables gives the so-

M M F - -_ __B,Annihj latcdFlux

in Core Plasma

4R : Thickness of Cumnt
ClllT)'lnguycr(2)This is the concept of Modified Betatron readilydemonstrated in the thermo-nuclear fusion community.

Fig. 2. Field annihilation and a diamagnetic loop.
189

BD(t) = Bz(O, t) - Bz(O , 00) = IBz(O, 00) 1 exp

7rr,
cos 2L

(4)
-4

InA

Z~ [Ohm-mJ .

(5)

Te

== nkT ew ==

i

t .2

JoTJTDdt

2

exp

/1-0

o

0.86

IB z (0 ,00 )1

IB z (0,00)1 2

(2t )
-TD

(at t = TD).

!!:.

1" f
... g"c~ 1il~

0. 6

5

2

0

1

615

V,.,(t)-0.483(1.exp( ·1/13))~- ... C ......

0.4

.....

is

oS

~

820

!

1

"'-

-.. -1i.-.-"-'

I

410

I

... 1 0 .2
~
::-

~

e

.

,

I

0.8

205

1
z

10

20

3d
Time, I Im_]

40

50

60

o

Fig. 4. Diamagnetic signal data and deduced Tew
time-history.
(6)

/-Lo

corresponds IBz(O, oo)I/BECR = 3.7% and 4.7% for
Z = 1 and 2, respectively.
Suppose 100% of the ECR field 0.357T was annihilated, Eq. (6) gives WJ = 1.01 X 105 J/m 3 if ne = 10 12
cm 3 , yielding the theoretical maximum T ew = 631 ke V.
Of course, this T ew is significantly over-estimating,partly because the uniform field (Bzo) in the core ismuch smaller than BEcR in practical devices.
Figure 5 shows a proposed experimental setup tomeasure T ew via the HeI visible spectroscopy. T ew canbe determined from the singlet/triplet (443.7 nm/412.1nm) line intensity ratio, which has readily been predicted as a function of T e by the authors. 5 ) This setup
is equipped with a constant solid-angle (dO) collection
optics, useful for scanning the diagnostic spots over theentire radius . This becomes important at the time tomeasure the absolute spectral intensity for determination of new at different radii.

Core Plasma

Fig. 3. Field diffusion and field annihilation heating (FAH)mechanisms.

&8le,I:5
Unit: mm

The annihilating or diamagnetic field, Bd (t), is given
from Eq. (4) byBd(t) = BD(O) - BD(t) = IBz(O , 00)1·.

WJ I([B,(O,oo) ]'/Il.)-I.exp(.2V13)

<:>

III

Note that L in Eq. (5) is the scale length of theBz(r, t) inside the core (Fig. 3). The gradient of
Bz(r, t) should be supported by the current density
jg ~ (7r/2L) 'IBz(O, t)I/P,o, and this jg heats the local
plasma. The thermal energy stored in the core plasma
is given by

.

I

>- ~~

TJ = 1.04 X 10

T •• leV)
.

=

:

:

-

-

.

.

.

~

-

-

.

.

.

.

,

.

-

-

,

~

Q

~

......_ _ _ _:::::-

where

[1 -

exp ( -

T~)].

···················iiio~f·lI::--::-,.."....,..----' 1(7)This Eq. (7) is directly proportional to the integrated diamagnetic signal, because Vint ~ J V gdt= -SIBd(t)l. We found that the experimental diamagnetic signal 3 ) indeed obeys the diffusion modelof Eq. (7), and that TD ~ 13 ms as seen in Fig. 4.
The scale length of the core-plasma was found semiexperimentally to be 4 ) L ~ 0.04 m. Then, Eq. (5) gives
8'TJ = (P,o/TD)(2L/,Tr)2 = 6.27 X 10[Ohm-m]. Since
InA = 16 for typical ECRIS plasmas, the 'TJ in Eq. (5)gives quite reasonable values: T ew = 883 eV if Z = 1
and 1.40 keY if Z = 2. Here, Z = (Zi) = ne /~ni' These
T ew can be converted into WJ of Eq. (6), assuming
ne = 10 12 cm 3 , from which one can estimate the dissipated fields to be IBz (0 , 00) I = 132 G and 167 G if
Z = 1 and 2, respectively. Since BEcR = fc (Hz) /2.8x
10 10 = 0.357 T if fc = 10 GHz, those dissipated fields
190

.

~

-

-

~o

.

( t)
- TD

,

lution for the diffusing field:

Vacuum Vessel

Seuupolc Magnets(Sm-Co. 4Ox.50x4S0)

Fig. 5. Proposed diagnostics for T ew of confined electrons.

References
1) M. Niimura et al.: Proc. 12th lnt'l Workshop on ECRIon Source, Wako, 1995, p. 141.
2) K. Langbein: Rev. Sci . lnstrum. 61, 330 (1990).
3) C. Barue et al.: Rev. Sci. lnstrum. 63, 2844 (1992).
4) M. Niimura et al.: Proe. 13th lnt 'l Workshop on ECRIon Sources, College Station-TX (1997), p. 52.
5) M. Niimura et al.: RIKEN Accel. Prog. Rep. 28 , 152(1994).

RIKEN Accel. Prog. Rep. 31 (1998)

Production of Multicharged Os Ion Beams from Organic
Metal Compounds Using RIKEN 18 GHz ECRIS
M. Kidera, T. Nakagawa, Y. Miyazawa, M. Hemmi, T. Chiba, N. Inabe, M. Kase,
T. Kageyama, O. Kamigaito, A. Goto, and Y. Yano
For production of the metal ion beams by ECRIS(Electron Cyclotron Resonance Ion Source), several
methods have been developed and utilized. 1-3) Oneof these methods is called MIVOC (Metal Ions from
Volatile Compounds) method. 2 ,3)Very recently, various kinds of ions were successfully
produced using the MIVOC method from the RIKEN
18 GHz ECRIS. 4 ) In order to produce intense beams of
multicharged ions from these materials, we need a vapor pressure of 10- 4 - 10- 3 Torr. In the case of Os, thetemperature with which the vapor pressure becomes
higher than 10- 4 Torr is 2800 °C. Thus, it is very difficult to produce Os ions from solid Os. The MIVOC
method is a good method to produce such ions.
The experimental setup is the same as that describedin Ref. 4. The chamber was connected by a gas-feedingtube via a large conductance, regulation valve to control the flow rate of the compound vapor. A few tensof milligrams of the compound powder was placed at
the bottom of the MIVOC chamber. Air and moisture
were evacuated until the vapor pressure of the compound became the dominant pressure in the MIVOC
chamber. A gas-mixing method was not applied during the present experimeI).t. In order to minimize contamination, the plasma chamber wall was covered witha thin aluminum tube which is easily removable, if
necessary. 5)
Figure 1 shows the charge state distribution of the
Os ions produced from OS(C5H5h. The gas pressuresin the plasma chamber and in the extraction stage were
4.6 x 10- 7 and 3.1 x 10- 7 Torr, respectively. Figure 2
shows the beam intensity of extracted Os ions as afunction of RF power. In order to study the microwave

20

power effects, the ion source was tuned for Os29+. The
ion current showed a maximum at the RF power of 240
W. Then, the power was reduced step by step down to
100 W. No other parameters were changed. Integrated
Os (particle) currents stayed almost constant. Figure
3 shows the charge state distribution of the extracted
Os ions. The ion source was tuned for producing the
maximum intensity of each charge state.

100W

HOW

240W

----\

~

~ 0.3
~

~ 0.2

~

E

:/l

III

20
Charge State

Fig. 2. The beam intensity of Os ions as a function of
RF power. The ion source was tuned for producing the
maximum intensity of 29+ ion.
Os

Fig. 3. The charge state distribution of extracted Os ions.
The ion source was tuned for producing each charge
state.

Tuned for 0529 +Gas Os(CSHS)2
c 3RF power 240 W
0 4+
Gas pressure
Plasma chamber 4.6x10· 7 Torr
3.1x10·7 Torr

We have successfully produced multicharged Os ionsfrom OS(C5H5h using the RIKEN 18 GHz ECRIS.
The beam intensities of the Os28+ and OS33+ ions were
10 and 2.5 ep,A at the RF power of 250 W, respectively.

03-

Vext = 10kV

29+

28+

References
1) R. Geller: in Electron Cyclotron Resonance Ion Sources
and ECR plasma (lOP, Bristol, 1996), p. 256 and references therein.
2) H. Koivisto et al.: Nucl. Instrum. Methods Phys. Res.

Analyzing Magnet Current (A)Fig. 1. The charge state distribution of Os ions. The ion
source was tuned for the 29+.

B 94, 291 (1994).
3) H. Waldmann and B. Martin: Nucl. Instrum. Methods
Phys. Res. B 98, 532 (1995).

4) T. Nakagawa et al.: Nucl. Instrum. Methods Phys. Res.
A 396, 9 (1997).
5) T. Nakagawa et al.: Jpn. J. Appl. Phys. 35, 4077 (1996).

191

RIKEN Aeeei. Prog. Rep. 31 (1998)

Recent Development of the Variable-Frequency
RFQ Linac for RILAC
o. Kamigaito, A. Goto, Y. Miyazawa, T. Chiba, M. Hemmi, M. Kase, S. Kohara,
Y. Batygin, T. Nakagawa, E. Ikezawa, and Y. Yano
As already reported,l) the new injector for the RILAC, consisting of the 18-GHz ECR ion source andthe variable-frequency RFQ, was installed in the RILAC beam line in August 1996. Figure 1 shows thelayout of the injector RFQ along with the six tanks of
the RILAC. Acceleration tests of the RILAC and RRC
have been carried out continually using the beams fromthe new injector since the installation.
150

o

0

'5

20

2S

30

35

40

Frequency (MHz)• RFQ
RFQ + RILAC

Ions accelerated through$o RFQ + RILAC + RRC

Fig. 2. Performance of the RFQ linac. The abscissa
and the ordinate represent the resonant frequency andthe intervane voltage, respectively. The output energy,
which is proportional to the intervane voltage, is also
indicated. The hatched area shows the region where theRFQ has ever been operated in the cw mode. The ionsaccelerated until July, 1997 are indicated by the closed
circles, the diamonds, and the open circles. The solid
curves represent the acceleration condition of ions, eachof which is indicated by the m/q-value. The dashedcurve shows the maximum attainable voltage with thepresent power source (40 k W).
Fig. 1. Photograph of the RFQ along with the RILAC .

As the first step of the acceleration tests, we havetested the RILAC using various kinds of beams accelerated by the new injector. The accelerated ions were
N 2,3+, Ar 2,4,5+, Fe 7,8+, Ni 8+, Kr 5,1l ,18+, Te 18 + andXe 7,17 ,19+. They are indicated by the diamonds andopen circles depending on the mode of acceleration in
Fig. 2.
Due to the high performance of the new ion source,2)
the beam intensity from the RILAC has remarkably
increased. The maximum beam intensity achieved at
the first step was 13 pJ-LA for the N 3+ beam at 2.5
MeV /nucleon, whose beam power was 450 W.
Another important result we have obtained is thatthe transmission efficiency of the RILAC has increased
to 70%, as illustrated in Fig. 3, while it was 50% withthe beam from the Cockcroft-Walton injector. In thetests, however, the transmission efficiency up to theentrance of the RILAC was about 70%. Consideringthat the efficiency through the RFQ was 88% in the
preliminary test,3) this result was not good enough.
192

100~--~~.--,,--,---.---.---.---,--~%~~-.

75~-+~~~···J=~~~==~~--~--~~;7-.::- -)... -?--,~~--+---+--..4,62
50 ~=i===r==~==t=~~···~··~··t·~··~···~·~~~451
2S

~

-

ECRIS18 (20kV max)
-

0

-

•

I

40

ECRIS18 (1 OkV max) I-+---+---!----+---I......&. . ... Cockcroft-WaltonJ

OL-__LI -_ _L -_ _L -_ _L -_ _L -_ _L -_ _~_ _~~ECRIS
18 ~-c::J-+--o-~~~Woso· .... .. ...
Cockcroft-WaltonFig. 3. Maximum transmission efficiency of the beamthrough the RILAC. The measurement was done with
the Faraday cups indicated in the figure. The solidline represents the result of the beam from the new
injector after the improvement in August, 1997. The
dashed and the dotted lines are those of the beams fromthe new injector before the improvement and the Cockcroft-Walton injector, respectively.

Therefore, about one half of the extracted beam fromthe 18-GHz ECR ion source was accelerated with the
RILAC.
As the second step, we started the acceleration testsof the RRC with the upgraded RILAC in December
1996. The accelerated ions were Ar 5 +, Fe 7 +, Ni 8 +,Te 18 +, Kr 18 + and Xe 17 ,19+ at the frequencies of 18.0,
18.8, 19.1,20.5,22.9 and 28.1 MHz. They are indicatedby the open circles in Fig. 2.
In the first test using an 36 Ar 5 + beam, we achieved
the beam current of 1 pp,A, extracted from the RRC
for the first time. In this test, about one fifth of theextracted beam from the ion source was accelerated to
the final energy of 7.5 MeV /nudeon. The beam power
was 300 W.
One of the advantages of the new injector is thathighly charged ions are readily generated with the 18GHz ECR ion source. Therefore, the charge stripper
before the RRC has become unnecessary for the lowenergy beams of the medium-heavy ions mentioned
above, and consequently the stability of the beam has
been improved.
On the other hand, the extraction voltage of the
ECR ion source should be very low for the highly
charged ions because the maximum extraction voltage
was set to be 10 kV. For example, the extraction voltage was only 3 kV in the first test using the 36 Ar 5 +beam. This situation is not good for the beam intensity which is roughly proportional to the extraction
voltage to the three half power.
Therefore, in August 1997, we raised the maximum
extraction voltage to 20 k V in order to increase thebeam intensity further. The vanes were replaced correspondingly, whose parameters are listed in Table 1.
After the improvement , the beam intensity has increased by a few times as expected. For example,
the intensity of Ar 5 + beam accelerated through the
RILAC has increased to 25 ep,A from 10 ep,A at 0.7
MeV /nucleon. Moreover, the maximum transmission
efficiency has been improved, as shown in Fig. 3. The
maximum beam power ever achieved with the RILAC
is 560 W for 0 5 + at 2.5 MeV /nudeon.
At the same time of replacement of the vanes, an additional Faraday cup was installed just after the RFQ
in order to measure the transmission efficiency throughthe RFQ alone. According to the measured data, theTable 1. Main Parameters of the RFQ.
1 - 07.1997

1 08.1997 -. . ·Frequency·(MHzr·....................r . ·f;r7..~"3·~f'2rT:;:4 . ~·3'~i:'6·
Mass-to-charge ratio (m/q) l
Input energy (keV/q)l
Output energy (keVIq)l
Input emittance (mmemrad) ~Vane length (cm)lIntervane voltage (kV)1
Mean aperture (r o:mm)
1Min. aperture (amin:mm)l.
Max. modulation (m)1Focusing strength (B)~Max. defocusing strength l
Final synchronous phase l

6 - 26

l

10

1

l

6 - 26
20
450

~

1451t

450
145 1t
142
33.6
7.70
4.17
2.70
6.8
-0.30
-25 0

l
1
1

l

1

i

1

l

153
36.8
8.08
4.67
2.41
6.8
-0.30
-300

efficiency was 92%, being slightly larger than that obtained in the preliminary test. The efficiency up to
the entrance of the RILAC was, however, 80% at maximum as shown in Fig. 3. This means that some portion of the beam is lost in the matching section between
the RFQ and the RILAC. In fact, it was recently foundthat the drift tube of the rebuncher has a smaller aperture than the actual beam size. New drift tubes areunder fabrication to give a larger acceptance for the
rebuncher.
In September 1997, we tested the RRC with thebeam from the upgraded injector. In the first test, we
extracted Argon beam of 1 pp,A from the RRC. Thisintensity is the official limit allowed for our facility. If
it were not for this limit, more intensive beam could
have been extracted. In the second test using Xenon
beam, the extracted beam current was 200 pnA. The
overall transmission efficiency was about 10% in thesetests. In spite of this low efficiency, the beam intensity
after the RILAC has increased by a few tenth of magnitude compared with those which had been available
with the Cockcroft-Walton injector.
In summary, the development of the injector RFQ
worked out satisfactorily. More efforts will be paid forthe improvement of the transmission efficiency.
References
1) A. Goto et al.: RIKEN Accel. Prog. Rep. 30, 186 (1997).
2) T. Nakagawa et al.: RIKEN Accel. Prog. Rep. 30, 188(1997).
3) O. Kamigaito et al.: RIKEN Accel. Prog. Rep. 30, 189(1997).

193

RIKE N Accel. Prog. Rep. 31 (1998)

Phase Stabilization of Injection Beam
to RIKEN Ring Cyclotron
M. Kobayashi, A. Yoneda, M. Kase, M. Kidera, A. Goto, and Y. Yano
When the RIKEN Ring Cyclotron (RRC) is coupledwith the one of its two injectors, RIKEN heavy-ion
linac (RILAC), the beam transmission rate throughthe RRC is sometimes limited by the phase instabilitiesof the injection beam from the RILAC. Recently, it
was tried to reduce the phase instabilities by a closed
control loop system and to improve the efficiency ofbeam transmission through the RRC.
The beam phase is measured by capacitive pick-up
probes in the beam transport line between the RILAC
and the RRC. In the signals from the probe, an instability is sometimes observed in the beam phase, which

has a frequency range of 10- 100 Hz. The instability is caused by the fluctuation of the rf voltages insome cavities of the RILAC. The average energy of abeam bunch at the exit of RILAC is affected by thisfluctuation, and the effective beam phase is spreadout after drifting along the long beam line down to
the re-buncher which is installed on a half way between the RILAC and the RRC. The broadening sometimes becomes larger than the phase acceptance of there- buncher, and therefore the beam transmission efficiency through the RRC becomes worse.
By using the phasemeter as shown in Fig. 1, a
RILAC

CAPACITIVE I'ICK UP

BF.AM.... - ...... ..................................... ..., ..... "' ........... - ...... . .
~PC

NEW SI(jNAL FEEDBACK LINE
17-45MHz

Fig. 1. Beam phase measurement and signal feedback system of the beam phase to the phase ofrf cavity of the RILAC. The part surrounded by dotted line is a newly installed feedback line.

second-harmonic component of the beam signal is extracted and converted into two analog signals, Acos¢
and Asin¢, where 'A' corresponds to a beam intensity
and '¢' the beam phase relative to rf. The system has
a response of 1 kHz and the data of these two signals
are taken through an interface-board of DIM 1 ) every
2 ms and stored in an 8 kB memory in it. And then,they are transferred to the host computer.
Figure 2(a) shows the data stored for a period of 4s for 0.5 MeV/nucleon 40 Ar beam. In this case, thebeam energy is 7.6 MeV/nucleon after the RRC. The
harmonic number of the RRC is 11, and correspondingly only the first 4 cavities of the RILAC are used.
Each point in the figure corresponds to one measurement. The distance between the 4th cavity (RF #4)

194

~cj1

= 27.0 deg (FWHM)~cj1 = 8.8 deg (FWHM)

.. r

~

i
(a)

Acos~

I

(b)

Acos~

Fig. 2. Observed beam phase at the RILAC: (a) and (b)show the data without and with the feedback system,
respectively. The !J.¢ in FWHM is 27.0 deg for (a), and
8.8 deg for (b).

to the probe is about 24 m. From this figure, it is clearthat the straggling width of the beam phase (azimuthal
direction) is quite large, while the beam intensity (radial direction) seems relatively stable. The straggling
value about the spread of the beam phase, 1:14>, is 27.0
deg in FWHM.
The phase and energy of the beam from RILAC are
given as a function of the rf phase and amplitude ofevery cavity in use. Among them, the energy depends
smoothly on the rf phase of the final cavity in use,
while the output phase does not change so much. In
other words, the energy of beam from the RILAC canbe tuned intentionally by adjusting the rf phase of the
final cavity2) without changing the beam output phase.
The fluctuation of beam energy at the exit of RILAC,
which is converted into the fluctuation of the beamphase at the phase probe location, can thus be suppressed by adjusting the rf phase of the final cavity.
According to this expectation, a new feedback system was developed as shown in the part surrounded bydotted line of Fig. 1. For the signal feedback system,
a local personal computer (PC) with the ADC & DAC
board is used. The two signals from the phasemeterare fed into the ADC, and the PC calculates 'A', 4>,
and the output signal V out . The relationship for this
output signal is given by V out = V 0+ (4) - 4>0) G, where
G and V 0 are the gain parameter and the offset voltage(+5 V constantly) of the system, respectively. The
cPo is the center of the fluctuating phase and an input
parameter. The V out is set on the DAC when 'A' is
within the available range. The circulation period isaround 80 fJ,s. The output signal from the DAC is fed
into the phase shifter which is inserted into the input
line of the low-level circuit of the RF #4 system. G isselected by changing its value to minimize the phasespread.
Figure 2(b) shows the data obtained using the feedback system for the same beam as in Fig. 2(a). The 1:14>
for a period of 4 s is reduced to 8.8 deg in FWHM, being one-third of the data without this feedback system.
Further, by the use of this system, an improvement in
the transmission rate of the RRC was observed.
References
1) T. Wada et al.: Sci. Papers LP.C.R. 79, 28 (1985).
2) M. Kase et al.: Sci. Papers I.P.C.R. 79, 45 (1985).

195

RIKEN Accel. Prog. Rep. 31 (1998)

Beam Orbit Simulation in the Central Regionof RIKEN AVF Cyclotron
D. Toprek, A. Goto , and Y. Yano
This paper describes a design modification of thecentral region at h = 2 mode of acceleration in the
RIKEN AVF cyclotron. We made a small modification to the electrode shape in the central region for
optimization of t he beam transmission. The central
region is equipped with an axial injection system. The
spiral type inflector is used for the axial injection. In
Ref. 1 is shown the shape of the electrodes of the central region of former design. In the former design, theion trajectory through the spiral inflect or (with parameters: A = 2.6 cm and k' = 0.0 which are defined inRef. 2) is analytically calculated, and the electric field
distribution in the four acceleration gaps is describedby a Gaussian function. In the present design, to treat
more realistically both the spiral inflect or and the central region, the electric field distributions in the inflector and in the four accelerating gaps have been numerically calculated from electric potential maps, produced
by using the RELAX3D program. 3 ,4) The optimized
inflect or has the following parameters: A = 2.2 cm
and k' = 0.3. For the simulation of the ion trajectories passing through the spiral inflect or and the central region we used the CASIN0 5 ) and CYCLONE 6 )programs, respectively. As for the magnetic field distributions in the central region, we used the measured
median plane map whose data were taken with an azimuthal step of 1.8 degree and a radial step of 2 cm.
Figure 1 shows the modified shape of the electrode in
the central region of the RIKEN AVF cyclotron. The
dotted area shows the area that has been cut off fromthe previously designed electrode, following to the new
simulation result.
Figure 2 shows the simulated phase space diagramsin two transversal planes 2 ) (u,Pu) and (h ,Ph) at theexit of the inflect or (solid line curves marked by theletters iu and ih, respectively) , together with theirinitial phase space diagrams at its entrance (dashedand dotted lines, respectively) . The emittance size int he initial phase space is Cu = 1407r mm mrad (dashedline) in the (u, Pu) plane and C h = 1307r mm mrad (dotted line) in the (h,Ph) plane. By using the CASINO,
we have made the simulation for seven particles whose
initial positions in the phase space are indicated byopen circles in Fig. 2. The simulation was made forthe three cases with different longitudinal momentum
values: 0Pv == !:::.p,)p = -0.01 , 0.0, and +0.01 , where
P is the total momentum of the ion. As seen in Fig.
2, the final phase space diagrams (solid lines) changes
depending on the momentum values. This shows thatthe coupling effects are important. Figure 2 shows thecase when the particle is inflected by decreasing the in-

196

o

>-- 2

2

. 3

4

x [em ]

5

Fig. 1. The modified shape of the electrode in the central
region of the RIKEN AVF cyclotron. The dotted area
has been cut off from the previously designed electrode.

2 5 0 +---~~L-~---L--~--~

200

~
-

.s
E
:::J
C
~

A = 2.2 em

150

R~

k '= 0 .3~.

= 1.61 e m./'......

o... opl' / f >
r . /

100

h

50

Q

J

0

\

.

0

f
"

"

-50
.oP. = 0.01
.op = 0 .0 0

~ - 100• oP: = -0.0 1- 150 fl . = 0 .0 mm X = 8 %Infl e ntronc.
14 0
mm m rod-200. . . . . . . . . • mfL . ntrone. " - 1.30 " mm m,..ad-250+-- -. -- -, - - , - -- . - - - . - - +-2
0
4-6 - 42
6
u or h coordinate [mm]---0- -f. -TI'

Fig. 2. Phase space diagram in two transversal planes(u,Pu.) and (h ,Ph) at the infiector entrance (dashed anddotted lines) and at its exit (solid line curves marked byletters of Iu. and Ih' respectively). The emittance at theinfiector's entrance is Cu. = 140n mm mrad (dashed line)
and ch = 130n mm mrad (dotted line) , and t he relativechange of longitudinal component of the momentum ofions is bpv = -0.01, 0.0 and + 0.01. The other marks
are explained in the text .

flector voltage by 8% (!:::.s = 0 mm, X = 8%) from thenominal (or analytical) value. This voltage of X = 8%
gives the best transmission.
The geometry of the central region has been tested
with the orbit simulation carried out by means of thecomputer code CYCLONE. In Fig. 3, the simulated
central trajectories of the reference ion are shown up to
the second turns. The trajectories are shown for threecases with initial accelerating phases of -50, -55 and-60 degrees. For this simulation the dee voltage wasassumed to be 50 k V. The initial radius r 0 and radialmomentum Pro were taken to be 2.26 cm and 0.67 cm,
respectively, which were obtained from the CASINO
calculations.
10

The same initial conditions as in Fig. 2 were used in
the simulation. Only those starting phases which givevertical envelopes contained within the smallest vertical aperture of the central region are shown. From
Fig. 4 we can see that the phase acceptance of the central region is about 10 degrees, which agrees with theresult in the former design.

5

E

~

3+-------L-------L-----~------_+

0

>-

2

-5

-10
-10

,., =

0 .357

h =

2

B. -

1.5 T

U. -

50 ~v

5o+-+---+__--+___+_---=~~----+----+---_+
~
N

-5

0

x [em ]

5

-1

10

Fig. 3. The central trajectory of the reference ion(TJ = 0.357, Eo = 1.5T, h = 2) in the central regionof the K70 AVF cyclotron for different values of thestarting phase </>0 with the equipotential contours of thenumerically by calculated field. </>0 = -50 0 (solid line),</>0 = -55 0 (dashed line) and </>0 = -60 0 (dotted line) .
The equipotential contours are plotted at each 10% of
the full dee voltage Uo .

We next tested the phase acceptance of the central
region of the machine by tracking the first two turnsof the ions and by looking at the beam envelopes inboth horizontal and vertical planes. The emittanceof the beam was reconstructed from its emittance atthe entrance of the infiector (see Fig. 2). The family of curves marked by letters of fu and fh (whichcorrespond to the (u,Pu) and (h,Ph) planes at the infiector exit) now correspond to the (z, pz) and (r, Pr )planes, respectively, at the entrance of the central region of the cyclotron. It was found that the phase acceptance was determined by the vertical beam spread.
Figure 4 shows the vertical beam envelope simulated
for the three different values of the initial phases cPo.

- - _ - - (/). -· - 50·
- 55'

.....

-60'

(/J. --2¢. -- 3+-------~------~----~r_----~

-50

150

350
8

550

750

[degJ

Fig. 4. The maximal vertical displacement of the beamin the first two turns for test ions in the K70 AVF cyclotron for different values of the starting phase </>0' The
short lines crossing the abscissa show the electric gap
positions, and the dotted lines parallel to abscissa indicate the minimal vertical aperture of the central region.

References
1) A. Goto et al.: Proc. 12th Int. Conf. on Cyclotrons andtheir Applications, Berlin, 1989, p. 439.
2) L. Root: M. Sc. Thesis, Univ. of British Columbia, 1972.
3) C. J. Kost and F. W. Jones: RELAX3D User's
Guide and Reference Manual, TRI-CD-88-01, Vancouver, 1988.
4) Lj. M. Milinkovic: RELAX3D Spiral Infiectors, TR30DN-89-21, Vancouver, 1989.
5) F. B. Milton and J. B. Pearson: CASINO User's
Guide and Reference Manual, TRI-DN-89-19, Vancouver, 1989.
6) B. F. Milton: CYCLONE VERSo 6.0, TRIUMF Internal
Report, June 22, 1989.

197

RIKEN Accel. Prog. Rep. 31 (1998)

Design of a Resonator for a Flat-Top Acceleration
System in RIKEN AVF Cyclotron
S. Kohara, Y. Miyazawa, O. Kamigaito, T. Chiba, and A. Goto
A resonator for a fiat-top acceleration system in the
RIKEN AVF Cyclotron is designed to improve theextraction efficiency and the energy spread of beam.
In order to generate the fiat-top accelerating voltage
on the dee, an additional resonator or a transmission
line is required, which is coupled to the fundamentalfrequency resonator with a coupling capacitor.1) The
fiat-top accelerating voltage is obtained by the superimposition of the fundamental frequency and fifthharmonie-frequency voltages. Structure and rf characteristics of the resonator designed for the fiat-top
acceleration system is described. 2 )A layout of the AVF cyclotron is shown in Fig.
1. The AVF Cyclotron has two resonators, each of
the coaxial quarter-wave-Iength type with a dee angle of 83°. The frequency range is from 12 to 23
MHz. The required maximum accelerating voltage
is 50 k V. A movable shorting plate has been used
for the coarse tuning and a capacitive tuner for the
automatic fine tuning of the fundamental-frequency
resonator. The stroke of the movable shorting plateis 2 m. The frequency-shift range of the capacitive
tuner is about 500 kHz. A grounded-cathode tetrode(4CW50,000E) amplifier is capacitively coupled to thefundamental-frequency resonator with a fixed vacuum
coupling capacitor (16 pF).lts maximum output power
is 20 k W. In general, the required amplitude of thefifth-harmonie-frequency voltage is about 1/25 of thefundamental-frequency voltage, when the voltage distribution of the acceleration gap is assumed to be fiat.
Therefore, the frequency range and maximum voltageof the fifth- harmonic-frequency system are estimatedto be from 60 to 115 MHz and 2 k V, respectively.
A cross-sectional view of the resonator designed forthe fiat-top acceleration system is shown in Fig. 2. It

Resonator

*

/'

0

Phase slit

o

Beam

100 emVacuum chamber

Fig. 1. Layout of the AVF cyclotron.

198

Movable shorting plate
Fundamental-frequency
resonator

Dee

Additional resonator

Capacitive tuner
16pF

I

4CW50,OOOE ~

I
I

Cc

1 ______ ____ __ 1

Capacitive tuner
Dee voltage pickup

°

50

lOOcm

Fig. 2. Cross-sectional view of the resonator for theflat-top acceleration system.

consists of the fundamental-frequency and the additional resonators to generate the fiat-top accelerating
voltage on the dee. The additional resonator is employed to excite a higher harmonie resonance in the
AVF resonator with the frequency five times of thefundamental frequency, but without a large shift in thefundamental frequency. The additional resonator consists of a transmission line and a coupling capacitor(Cc). The fifth- harmonie resonant frequency is generated by adjusting both the position of the movable
shorting plate (L5) and the coupling capacitance (Cc)of the additional resonator after the fundamental frequency of the resonator is set by the movable shorting
plate (Lavf).
The rf characteristics of the resonator was calculated with the transmission-line approximation. Figure 3 shows the positions of the movable shorting platesof the additional and the fundamental-frequency resonators to obtain the fifth-harmonic resonant frequencies. The highest position of the movable shorting
plate of the additional resonator is 50 cm when the
coupling capacitance is 30 pF. Shunt impedances calculated as a function of the fifth-harmonic resonant
frequency are shown in Fig. 4. The ratio of the voltage
at the extraction position to that of the injection position of the AVF cyclotron is from 0.85 at 60 MHz
to 0.49 at 115 MHz. Therefore, the required fifth-.......
0

50

250

40

200

~..--

~

~...:l

Q..u

Vl~

CU c:
-0

.S ~

t: c:

150

30

~&'j
;> ....
0_eCU ~0

20

o-e
c: ~
o CU
:~ -5

10

.s:E
....... -e

Q.. ....

0.00

C:'"

'€...:l0 ....
..c:0

100

50

60

70

80

90

100

110

120

o

6

u
~
o:s

.!lC

.5

4

00"
CU
CUt!::..c2~5;> ::se.s~...........
o c:

8-

c::l

en

OL-~-L~L-~-L~~.9 §50 60 70 80 90 100 110 120c:Fifth-harmonic resonant frequency (MHz)

o ::s

50

8

"0

.~"O
Vl

0

E

..c
0
C-

00
..c: Vl
Vl~

c: CU

Q.,

10

u

.......
0 .......

....CU ;>~e0.0'-".sE-

Q., .......

Fifth-harmonic resonant frequency (MHz)Fig. 3. Position of the movable shorting plates of the additional and the fundamental-frequency resonators calculated as a function of the fifth-harmonic resonant frequency. The coupling capacitance (Cc) is 30 pF.
harmonic-frequency voltage at 115 MHz is estimatedto be 1/17 of the fundamental-frequency voltage; its
maximum voltage is to be 3 kV. Power losses are estimated to be 2,900 W at 58.5 MHz, 560 W at 80 MHz,and 690 W at 115 MHz when the voltage is 3 kV.
A power amplifier for the fifth-harmonic resonant
frequency will be a solid-state wide-band amplifier(WBA) whose output impedance is 50 n. A capacitive divider is used to match the input impedance of
the additional resonator to the output impedance of
the wide-band amplifier. The capacitive divider con-Fig. 4. Shunt impedance calculated as a function of thefifth-harmonic resonant frequency. The coupling capacitance (Cc) is 30 pF.
sists of a coupling capacitor (Cl) and a variable capacitor (C2). In order to obtain a good impedance
matching, the capacitance of the variable capacitor isestimated to be from 90 to 120 pF when the coupling
capacitance is 3 pF. Fabrication of a model resonatoris in progress.
References
1) J. L. Conradie: National Accelerator Centre, South
Africa, Dissertation presented for the degree of Doctorof Philosophy in Physics at the University of Stelenbosch (1992).
2) S. Kohara et al.: Proc. 11th Symp. on Accelerator Science and Technology, Harima, p. 194 (199.7).

199

RIKEN Accel. Prog. Rep. 31 (1998)

New Emittance Measurement Using Two PPACs
A. Yoneda, H. Kumagai, M. Kobayashi, N. Fukunishi, M. Kase, A. Goto, and Y. Yano
A new emittance monitor has been developed, which
is designed to measure precisely the emittance of ahigh-energy beam generated by the RIKEN Ring Cyclotron (RRC). This emittance monitor consists of two
sets of two dimensional position sensitive gas counters(PPAC; parallel plate avalanche counter). Such PPAC
itself can work as a beam image monitor for a lowintensity beam. I}
Figure 1 shows the principle of the emittancemeasurement using two PPACs. Suppose that two
position-sensitive detectors are installed in a straightbeam line with a distance of L (2.9 m in this case)in the interval, and that the sensitive areas are large
enough to ensure all particles in the beam pass throughthe both detectors. When one particle passes though
the detectors, two sets of two-dimensional position
data, (Xa,Y a ) and (Xb,Y b), are obtained; where thesuffix 'a' and 'b' are for the first (upstream) detector
and the second (downstream) one, respectively. From
the obtained data, a position and an angle of the particle are calculated easily as (Xa,X') and (Ya,Y'), where
X' = (Xb-Xa)/L and Y' = (Yb-Ya)/L. If the thicknessof the detector is thin enough, the trajectory is notaffected by the existence of the detector. The deflection of a beam due to the penetration of a counter(upstream) is estimated using by the Ziegler formula.
Total thickness of the PPAC is estimated equivalent
to 1.9 mg/cm 2 Mylar. As a result, the scattering angle of the beam after passing the PPAC in the beamline is about 0.2 mrad for the case of 70 MeV/nucleon
I2C beam. This means that the effect of angular scattering of the beam by the PPAC itself is negligible.

After accumulating these data (Xa,X') and (Ya,Y') fora number of particles in the beam, the beam emittancecan be determined.
The electrode assembly of the PPAC consists of ananode and two cathodes on both sides of the anode.
These electrodes are parallel each other with 4.0 mm
interval. The anode is a thin gold layer (60 p,g/ cm 2 inthickness) which is deposited on a 2.5 p,m-thick Mylar
film on its both sides. On the other hand, the cathode has 51 gold strips (60 p,g/cm 2 in thickness) whose
pitches are 1.0 mm on a 2.5 p,m-thick Mylar film andhence, the sensitive area is 50*50 mm 2. The charge division method is employed for the signal readout. Twosignals from both ends of the cathode are taken outside, and are used to get the position information. One
cathode is used for the measurement of the X-position
and the other one is used for the Y-position.
These electrodes are set inside of the aluminum box
which has two windows (for the beam entrance andexit) of 50*50 mm 2 in size, and the distance of the two
windows is 32 mm. The window film is 2 p,m- thick
Mylar, on the surface of which aluminum (8 p,g/cm 2) isdeposited. This counter box has a gas inlet and outlet
and has four feedthroughs for the position signals fromtwo cathodes and one feedthough for the bias voltage
to the anode. Two gas lines and five signal cables
are introduced to the atmosphere through a counter
support pipe. A gas of isobuthane is supplied by astable gas flow, keeping the pressure inside the counteraround 8 torr.
The counter is set exactly on the beam axis remotely
when in use, and removed out of the beam area other

L=2.9mX" =~!>.-:~!1
L

Y' = Yb-Ya
L

--~.~

(Xa, X') (Ya, Y')

Fig. 1. Principle of the emittance measurement using two PPACs in series.

200

time. Two PPACs have been installed inside the beamdiagnostic chambers separately, immediately after the
extraction of RRC. There is no focusing element between the two chambers.
The PC takes eight signals, and only if the eightsignals are all above the threshold, 10% of the maximum data range, it accumulates these data. If there isno threshold setting, accurate data cannot be obtained
about the position information.
A test of the emittance measurement was performed
with a beam of 110 MeV/nucleon 22Ne. The obtained
data of the spatial distribution and emittance of thebeam are shown in Figs. 2 and 3. The obtained emittances are 15 nmm ·mrad for horizontal plane and 4.6
nmm·mrad for vertical one. The emittance in the horizontal plane might be enlarged due to a multi-turnextraction and/or momentum dispersion effects. In
Fig. 4, several spots due to the multi-turn extraction
can be observed in the vertical plane.
From the result, it is clear that the PPAC system
is very useful for the precise measurement of a lowintensity beam whose current not to exceed 104 particles/sec. By using these PPACs as beam emittance(Xa,Ya) 5mm1div---I(~---------~--------~~----~--------.
X,ex) 5mmldiv,ImRidiv(y,ey) 5mmldiv, ImRldiv

-

+

+

,

Fig. 3. Beam emittances measured by the PPAC. Fora beam of 110 MeV/nucleon 22Ne, the obtained emittances are 15 7rmm·mrad for horizontal plane and 4.6
7rmm·mrad for vertical one.

(x. ex) 5mmldiv, ImRldiv( Xb,Yb) 5mm1div

Fig. 4. Beam emittances measured by the PPAC. Several
spots due to multi-turn extraction effect are shown bylog scale in ordinate.
+

- . :

.ifIIir+

monitors, more accurate experiments may become possible.
References
Fig. 2. The spatial distribution of a beam image measured
by the PPAC.

1) H. Kumagai et al.: RIKEN Accel, Prog. Rep. 28, 127(1995).

201

RIKEN Accel. Prog. Rep. 31 (1998)

Heavy Ion Microbeam Project in RIKEN Accelerator Research
Facility
N. Fukunishi, M. Kobayashi, A. Yoneda, M. Kidera, M. Kase, and Y. Yanohigh, and insertion of few devices into the present beamline is good enough to realize microbeams. We choose
the aperture of 50 /.Lm as a collimator for a first step ofour project. The test bench of the collimator has been
completed. 2 ) The E5C course of the RIKEN Accelerator Research Facility was chosen as the microbeam
course, and the beam transport was designed to makea parallel beam at the collimator in order to reduce undesired beam scattering. We show in Fig. 1 an example

Recently, biologists have suggested a new type ofexperiments in which specified cells or organs are irradiated with heavy ions in order to elucidate complex
communication mechanism between cells or between
groups of cells. To promote this program, we are now
planning to construct the new beam course which canprovide microbeams. 1 ) For producing a microbeam, we
employ a beam collimation method because the beam
intensity of the RIKEN Ring Cyclotron is sufficiently

E 30

.s 20

QA02

QAll

QD12 QD13=:-~ 10 -',) ~o~ 0.0 ~•• - .... ia5 -10
V~~~ -20 ~
co -30
Q)

o

-- .

.- ..

DAA1&
DMAI

III

10

,I

,

QD16

rl
"
.. ........
fJ slit~.~~...... ..,'II

QD5C Collimator

QD17 QD18 QD19 QD1A

,
slit
r.

===-

I

20

QD14 QD15"/.~

I, ~ . .

III-......

"'t><~ ,. -, ,,~ •• '

,

~

K ...

.

DMD5

I

30
40
50
Distance from A01 (m)60

70

I'...:

SWSI

"

-

-,

I

80

Fig. 1. Beam envelope in the E5C course. A solid (dashed) line is the horizontal (vertical)
component. The AOl point is the object point of the beam optics. Vertical lines show
positions of magnets, slits, and the collimator.

of calculated beam envelopes based on the first ordertheory of beam optics. The transmission efficiency is
1.35 * 10- 9 in this case, and the resulting current of the
microbeam is 840 ions/second for a 100 pnA heavy-ion
beam.
Figure 2 shows a conceptual design of the irradiation system. The thickness of the collimator is 10 mmeven when a heavy metal is used, because the energy ofheavy ions is quite high. In addition, we use a positionsensitive Si-detector (PSD) to resolve the beam axis.
A microscope is installed to determine the target position. We fix the target on a movable stand and drive
it using a stepping motor. We choose the minimum
step as 50 /.Lm. Utilizing these apparatuses, we set thetarget precisely on the beam axis. The scintillation
counter placed above the target numerates the population of heavy ions. We also prepare a range shifterin order to vary the linear energy transfer. We set all
devices on the same table which defend them from vibration. A beam profile monitor and a Faraday cup are
prepared to assist the beam tuning, and we set themoff from the beam axis during experiments. The firstexperiment with this system is scheduled in 1998.

202

Fig. 2. Conceptual design of the irradiation system.

References
1) N. Fukunishi et al.: Proc. 11th Symp. on Accelerator
Science and Technology, Oct. (1997), to be published.
2) M. Anzai: Private communication.

RIKEN Accel. Prog. Rep. 31 (1998)

Initial Design of a Charge State Multiplier System
for RIKEN RI Beam Factory
A. Bandyopadhyay, O. Kamigaito, A. Goto, and Y. Yano
The RI-beam factory project envisages to use a
Charge State Multiplier!) (CSM) after the RILAC.
The CSM consists of an accelerator - charge stripper- deccelerator combination. A charge stripper placed
after the accelerating section increases the q/ A ratioof the beam and the decelerating section brings down
the rigidity of the beam within the acceptable limit of
the RRC.
The initial parameters for the CSM have been fixedby considering the acceleration of 238U ion at the frequency of 54.4 MHz. At present, the aim is to startwith q = 22 and optimize the production of q = 58
from the stripper. Considering various aspects, thefinal energy for U 22 + have been fixed around 3.84
MeV /u and the expected charge fraction of U 58 + at
this energy is 13.82%.2)
The focusing elements will not be placed within thedrift tubes but in between the tanks in order to reduce
the wall losses of tanks. I) As a consequence, the lengthof the individual tank should be moderate to confine
the beam within reasonable transverse limits. It has
been decided therefore to make four accelerating tanks
and two decelerating tanks to reach this goal.
In order to find the dimensions of drift tube lengths
and gap distances between the drift tubes, a program
CELLGEN has been developed. The transit time factor has been calculated assuming a sharp edge approximation of the electric field between the drift tubes andassuming that the particle receives the total energy at
the middle of each gap. In this design, the gap lengthin each tank has been kept same, equal to the half
length of the first cell in each tank.
A beam dynamics code ARLIN1 has been developed
for calculations of the transverse beam dynamics in
the CSM. It is a first order matrix multiplication code
capable of calculating the beam profile in the transverse plane starting with initial phase ellipse parameters. The defocusing effect of RF field in the drift-tube
gap has been approximated to the action of a thin lens
kept at the center of the gap. The change of the beamemittance due to the acceleration has been properly
taken into account by adjusting the Twiss parametersat the center of each gap.
The optimization of quadrupole field strengths in between the tanks is yet to be implemented in the ARLIN1 program. Therefore, the code TRANSPORT 3)
has been additionally used for the initial optimization of the quadrupole fields for efficient transmission
through the CSM. The arbitrary matrix option of thecode has been used to describe the effect of RF defocusing in the tank. With these optimized fields thecode ARLIN1 has been used to find the beam profile.
Another code NEWCEL21 has been developed to
study the longitudinal beam dynamics. Given the values of the synchronous phase and energy and of the half
widths of their spread, the program generates a phase
ellipse in the longitudinal phase space and tracks the
motion of each particle up to the end of the tank. One
can then draw the phase profile at any location within
the tank.
The fixing of initial parameters of the drift tubes described above were performed assuming a fiat voltage
profile in each tank. In practice, however, the voltage
profile is not exactly flat and it changes with frequency
also. We have used the three dimensional RF structure analysis code MAFIA for the calculations of RF
parameters and of the voltage distribution within thetanks.
We have opted for an IH type of structure (Fig. 1)

drift tube
Beam_

movable shorting
plate

1m
I

Fig. 1. Schematic diagram of a CSM tank.

for the CSM, as in the velocity range of operation thisstructure provides the highest shunt impedance. On
top of this, the structure of the CSM should be of continuous frequency-variable type in the frequency rangeof 36 to 76 MHz, and it should have a maximum possible flat inter-gap voltage distribution in each tank.
Further, the voltage distribution should not changemuch with the frequency. Figure 2 shows the optimized voltage distribution within the first tank for different frequencies. Identical results have been achieved
for all the tanks. The dimensions of the ridge is foundto be very critical in determining the voltage profile
within the tank. The current through the RF contact
between the ridge and the shorting plate is a matterof concern, especially at higher frequencies. Table 1
shows the important parameters for the CSM tanks.
The beam dynamics have been studied in the final203

---:- 1. 2 ~------r---""'---.--r-=7"""5~.=9=6
.0
•
62.~~
1.1
39.0"

::s

E

.~

(!)

g' 1.0~1o> 0 .90..

oo 0 .8

L-_~oo L-.L---'---'----'----'---'---'_ _~_ _~_~

15

10

5

2~~~~....,--.--~--.

20

Gap NumberE~1Fig. 2. Optimized voltage profile in the first CSM tank atthree different frequencies in MHz.

>-

OL--'--~-'-~~~~

Table 1. Tanks 1- 4 are the acceleration section and tanks
5-6 are the deceleration section. cPs denotes the synchronous phase. The input (Ein) and output (Eoud energies correspond to the acceleration condition at 54.4
MHz, where the initial parameters were fixed. The effective shunt impedance (Zs), Q-value, the maximum
current density on the sliding contact (J), and the wallloss (P) are estimated at the highest frequency of 76
MHz.
Tank I

Tank 2

Tank 3

Tank 4

Tank 5

Tank 6

Length (m)

3.051

3.525

3.940

4.313

3.663

2.914

Height(m)

1.750

1.750

1.750

1.750

1.750

1.750

Width (m)

1.050

1.050

1.050

18
-25

18
-25

E;n(MeV/u)

1.476

2.070

18
-25
2.661

1.050
16
25

1.050

No. of Gaps
• • (degree)

1.050
18
-25
3.251

3.840

2.650

Eou, (MeV/u)

2.070

2.661

3.251

3.840

2.650

1.476

155.3

131.0

114.9

102.0

111.6

155.9

Q-value

29321

31144

32757

31063

92

P(kW)

92
126

130

31972
79
132

32767

J(Ncm)

73
136

Inter-gap Voltage (kV)

430

430

430

430

71
77
382

79
81
382

step with the optimized voltage profile, and the results of this study are shown in Figs. 3 and 4. The
initial beam is assumed to have an emittance of 30n
mm-mrad in both transverse phase planes, and the longitudinal emittance being 450n keY lu-degree. It has
been found that the beam is fully transmitted throughthe CSM with the optimized quadrupole fields.

48

12 16 20 24 28

Distance (m)Fig. 3. Beam profile along the distance of the CSM in
two transverse directions, where the inter-gap voltage
distribution was calculated with the MAFIA code.

4 CSM ENTRY

CSM EXIT

2

o
w

16
25

Zs(MW/m)

204

o

'-..
w
'0

......... -2- 4 L-_L-----..J ' - - - ' - - - - - '

-40

-20

~s(Deg)020~s(Deg)40

Fig. 4. Particle simulation in the longitudinal direction
using the inter-gap voltage distribution calculated with
the MAFIA code.

References
1) M. Tomizawa: RIKEN Accel. Prog. Rep. 29 , 228(1995) .
2) K. Shima et al.: Atomic Data & Nuclear Data Tables
51, 173 (1992).
3) D. C . Carey, K. L. Brown et al.: SLAC-R-95-462.

RIKEN Accel. Prog. Rep. 31 (1998)

The Two Booster Ring Cyclotrons for RIKEN RI Beam Factory
A. Goto, T. Kubo, H. Okuno, T. Kawaguchi, T. Mitsumoto, T. Tominaka, S. Fujishima,
J.-W. Kim, K. Ikegami, N. Sakamoto, S. Yokouchi, K. Sugii, T. Wada,
J. Ohnishi, T. Morikawa, Y. Tanaka, and Y. Yano
In a previous design,l) the first one (4-sector ring cyclotron) of the two booster ring cyclotrons was planned
to be superconducting one. After a further study,
however, we found that it had better be a roomtemperature (RT) one. The reasons why the RT cyclotron was considered advantageous compared withthe original superconducting design are: the sector
magnets of the RT booster in question can be designed
to consume only 320 k W of power, no greater than that(480 kW) of our ring cyclotron currently in operation
at RT (RRC); and the new booster can be easily designed after this RRC know-how (if it is chosen to bea RT one), because its structure and size are similar
to those of familiar RRC.
Thus, we have renamed the 4-sector ring cyclotron
as IRC (Intermediate Ring Cyclotron) from the former
name SRC-4, and the 6-sector ring cyclotron as SRC(Superconducting Ring Cyclotron) from SRC-6.
Figure 1 shows a plan view of the designed IRC.
Total power consumption of four pairs of main coils
and twenty pairs of trim coils is 320 and 220 k W at
the maximum magnetic field of 1.9 T, respectively. A
flat-top rf resonator is used along with two main rf
resonators. The main rf resonator is of a single-gap
type with a rotatory plate; the flat-top resonator is ofa single-gap type with a shorting plate. 2 ) Details of all
the components except for the rf resonators are being
designed after the components of RRC.

Sector .
Ma~t

Fig. 2. Plan view of SRC.

Fig. 1. Plan view of IRC.

Progress Report.
Fabrication of the prototype sector magnet of SRC
has been continued: measurements of mechanical andelectrical characteristics of the superconducting wires
for the main and trim coils as well as detailed designof how to fix the coil vessel onto the cold pole were
made. The items measured relating to the mechanical characteristics of the superconducting wires were:
tensile strength, stress/strain hysteresis, fatigue, andstress/creep characteristics at room temperature and77 K. The items measured on their cryogenic and electrical characteristics were: heat flux, Hall effect, andmagnetic resistance at 4.2 K. Quench stability test wasalso made at 6 T for both the main and trim coils bymaking a small model of two-coil configurations. The
results of these measurements were in good agreementwith the design. Details of them and the design of the
prototype sector magnet are reported elsewhere in thisProgress Report.
The prototype sector magnet of SRC is scheduled
to be completed in the summer of 1998 after a halfyear delay from the first schedule. Until then planned
to be made are: a model of superconducting magnetic
channel and three units of sector magnet models with
1/6-scale in order to simulate the electromagnetic force
exerted from the adjacent sector magnets.

Figure 2 shows a plan view of the designed SRC.
Details of orbit analysis and design of the components such as the sector magnets, the rf resonators,
and the injection system are reported elsewhere in thisReferences
1) A. Goto et al.: RIKEN Accel. Prog. Rep. 30,196 (1997).
2) T. Saito et al.: Proc. 12th Int. Conf. on Cyclotrons andTheir Applications, Berlin, p. 201 (1989).

205

RIKEN Accel. Prog. Rep. 31 (1998)

Orbit Analysis of RIKEN Superconducting Ring Cyclotron
T. Mitsumoto, A. Goto, T. Kawaguchi, J.-W. Kim, Y. Tanaka, T. Kubo,
H. Okuno, T. Tominaka, S. Fujishima, and Y. Yano
The RIKEN superconducting ring cyclotron is one of
the main accelerators for the "RI Beam Factory" which
has started its construction as the next project of
the RIKEN Accelerator Research Facility (RARF). 1)
The Superconducting Ring Cyclotron (SRC) is expected to boost the energy of ion beams up to 400
MeV /nucleon for light heavy ions like carbon, andup to 150 MeV/nucleon for very-heavy ions like uranium. Beam current is expected to be more than 100
pp,A for light heavy ions and about 0.2 pp,A for 150
MeV /nucleon for uranium ions. Figure 1 shows theregion of expected ions from the SRC (grey area) andtypical ions (white circles).

'2
0

400

Fig. 2. Layout of the SRC.

300

coils for base field generation; five sets of superconducting trim coils for coarse adjustment to the isochronous
field; and about 20 sets of normal conducting trim coils
for fine adjustment to the isochronous field. Magnetic
field distribution was calculated by a three dimensionalcode, TOSCA.2)
Size of the superconducting main coil is 284 mm(width) x 310 mm (height). The maximum excitation
current is 6 MA per one sector magnet (two coils). The
superconducting main coil is installed inside a He vessel made of stainless steel which is tightly fixed to thecold pole.
Five sets of the superconducting trim coils are placedon the inner surface of the cold pole. Two sets at theextraction side have current returns at the extractionside, which are not wound along beam orbits but are
just straight in the beam region in order to avoid concave curvature of conductors. The rest three sets havecurrent returns at the injection side. Schematic view ofthe superconducting trim coils is shown in Fig. 3. The

0

U
::s
r::

>0

6>. 200
e!>
0
r::

~

100

0.1

0.2

OJ

0.5

0.4

q/A

Fig. 1. The region of expected ions from the SRC is shownby grey area. White circles show the typical ions used
for design calculation.
Main parameters of the SRC are listed in Table 1.
Velocity gain factor is 1.51. Figure 2 shows a layout of
the SRC. Six sector magnets, three main resonators,
one flattop resonator, and injection and extraction devices, together with injection and extraction orbits, areshown.
Table 1. Main parameters of the SRC.
Number of sectors
Harmonics
Average radius:

Injection
Extraction

Number of cavities

Main

6
6
3.56m
5.36 m3

Flattop
Rotational frequency

3.0-6.36 MHz

In order to realize the high magnetic field and various magnetic inclinations, the sector magnet of the
SRC has the followings: a set of superconducting main
206

Fig. 3. Configuration of the superconducting trim coils isshown. Two of five sets have current returns at the extraction side and the others have them at the injectionside.

first coil (of leftest in Fig. 3) on the injection orbit iswound along the beam orbit, then the curvature gradually becomes straight towards the extraction side.
The normal conducting trim coils are one-turn coils
which are installed inside the cryostat chamber wall.
We plan to use 20 coils at the acceleration region andone or two more coils at both injection and extraction
regions. The maximum current of each coil is considered to be 500 Amps.
Shape of the yoke of sector magnet has been optimized in order to give an appropriate focusing force
and to receive a tolerable shifting force of the coldmass. Figure 4 shows the upper half of the sector magnet.

Influence of the resonances at V z = 1 and V z = 1.5
was studied. The minimum axial betatron frequency
is set to be 1.05 in order to keep the axial shift ofbeam within ±5 mm. The resonance at V z = 1.5 canbe crossed. The amplitude increase by crossing theresonance is less than 10%, however. Figure 5 shows
the working paths of typical ions.

1.6

'"

:>

g 1.5
CD

::J

I

(1)

1.4

2 1.3

S

Z

]i

~

By using the main coils and five sets of the superconcudting trim coils, it is possible to adjust various
distributions of isochronous fields within ±0.1 %. The
normal conducting trim coils can improve the errors to
the isochronous condition from ±0.1% to ±0.01%.

(5)

1.2
1.1
1.0
1.0

Fig. 4. Schematic view of the upper half of yoke is shown.
Length, width and height of the yoke are 7.55 m, 3.3 m
and 3.0 m, respectively.

(2)
(3)

1.1

1.3 .
1.2
1.4
1.5
Radial betatron frequency Vr.

1.6

Fig. 5. Working paths of the radial and axial betatron frequencies of typical ions: (1) 238U49+ 100 MeV/nucleon,(2) 238U58+ 150 MeV/nucleon, (3) 84Kr30+ 300
MeV/nucleon, (4) 16 0 7 + 400 MeV/nucleon, (5) 12C6+400 MeV/nucleon and, (6) 16 0 7 + 200 MeV/nucleon.

References
1) Y. Yano et al.: RIKEN Accel. Prog. Rep. 31, 181(1998).
2) Vector Fields Limited, Oxford, England.

207

RIKEN Accel. Prog. Rep. 31 (1998)

Design of Sector Magnets for RIKENSuperconducting Ring Cyclotron
T. Kawaguchi, T. Mitsumoto, H. Okuno, T. Kubo, T. Tominaka, S. Fujishima,
J.-W. Kim, K. Ikegami, N. Sakamoto, A. Goto, and Y. Yano
The RIKEN Superconducting Ring Cyclotron, SRC,
will be one of the main accelerators for the "RIKEN
RI-Beam Factory" .1) Six superconducting sector magnets are to be used in the SRC.
Our progress made for the design of the sector magnets during 1997 is as follows: (1) A detailed design ofthe main and trim superconducting coils was finalized;(2) Mechanical stress and deformation of the main coilvessel caused by the coil's electromagnetic force wereanalyzed, and the dimensions of the coil vessel wereofixed; (3) Superconducting wires of 15.4 km and 4.6 km
in length to be used for the main and trim coils werepurchased for a prototype magnet;2) (4) Two smallcoils were made using the two kinds of superconducting
wires mentioned above, and their stabilized currents
against coil quench were measured. The results haveverified the validity of our design;3) (5) Constructionof the prototype magnet is in progress at respective
manufactures.
The present design status is as follows. Figure 1

10m

I
I FZ SUPPORTIICOLD POLEI YOKEI

MAIN COIL(super)

I

TRIM COIL(super)

YOKE

1:I
K

FX SUPPORT

_

5.4m

I X

POLE LINKMID

TRIM COIL

MIC(nonna!)80KSHIELDBEAM
CHAMBERVACUUM VESSEL

Fig. 1. Cross-sectional view of the SRC sector magnet.
shows the cross-sectional view of the SRC sector magnet. The basic parameters are shown on Table 1. Maincomponents of the magnetic elements are superconducting and normal-conducting coils, cold poles, anda yoke. Two kinds of superconducting coils are used:i.e., a pair of main coils and one group of trim coils,
and these superconducting coils are mechanically fixed
to the cold-poles through their vessels. Another groupof normal-conducting trim coils is arranged on the upper and lower surfaces of the beam chamber. Superconducting coils are all cooled by liquid helium andlocated in a cryostat to keep their temperature to be
4.5 K. The cryostat is like a big vacuum bottle, which
consists of a vacuum vessel and an 80 K thermal shield.
One of the most serious points of design is how
to control and how to support the huge electromagnetic force exerted on the superconducting coils. The
208

Table 1. Parameters of the sector magnet.
Average radii of beam injection
3.56m
extraction
5.36m
Sector angle of main coil
25 degree
Maximum magnetic fieldin the beam orbital area
4.5 T
5.S T
in the main coilin the trim coil
5.0 T
Main-coil's ampere turns per magnet 6.0 MA
Coil cooling method
LHe bath cooling
Stored magnetic energy for 6 magnets 390 MJ(75 % .in air, 17 % in poles, 8 % in yokes)
Maximum operation currents
S,OOOAfor main coilfor trim coil
SOOA
Iron weight of 6 magnets
216 tons
poles
3,630 tons
yokes

magnetic forces on the cold mass calculated with 3-D
TOSCA/OPERA code are shown in Fig. 2. We haveadopted a cold-pole arrangement which gives a mechanical support against the huge magnetic force of themain coil, and gives a reductions in the ampere-turns

2

200
150

,-..,
I::

g'"

100

u..N

50

g'"
I::

>..

u..><

0

u..><

-50
-1

-100
0

2

3

4

5

6

Ampare turns I magnet (MA)Fig. 2. Magnetic forces exerted on the cold mass. Fxy forhalf main coil (Expanding Force = EIFxyl). Fz for one
coil and one cold pole. Fx for a magnet.

and the magnetic forces, compared with a warm-polearrangement. The magnetic forces (Fxy, Fz) exerted
on the main coils are all supported by the cold-poles
through the coil vessels. The vertical magnetic force(Fz) is supported with two pole links which are attached to the upper and lower cold poles. The shifting
force (Fx) in the radial direction is supported with four
sets of the Fx supports which work at the same timeas the thermal insulations between the room temperature and 4.5 K regions. This force (Fx) is generated
by both of the arrangement of six sector magnets andthe asymmetric configuration of the coils and irons.
Another important point of design is how to preventthe coil quench. If a coil quench occurred in the maincoil, the operation of the SRC has to be stopped atleast for 2 weeks in order to re-cooldown of the coils.
We have applied a cryogenic stabilization method on
the main and trim superconducting coils to avoid coilquench. As the result of applying it, the average current density of the main and trim superconducting coils
were designed to be 34 A/mm 2 and 39 A/mm 2 , respectively.
Figure 3 shows the cooling diagram. Two refrigera-

RECOVERYRUPTUREDISK

co PRESSORSAFETY VALVE__---...J::.-;r-------,

BUFFER PASS

GHeBUFFER

TANK
10-15 atm

POWER LEAD GHe

TRANSFER TUBES

6 SECTOR MAGNETS &BEAM INJ/EXT MAGNETS

LHe BUFFER TANKCOLD BOX

Fig. 3. Cooling system diagram.
tors having a capacity of 500 W each at 4.5 K will be
used for cooling of the six sector magnets plus the beam
injection/ extraction magnets. The cold mass weight ofthe six sector magnets is 360 tons, and it will take one
and a half months for the cooldown of the cold massfrom room temperature to 4.5 K. We expect the SRC
to operate more than 6000 hrs a year, so the cold mass
should be kept in the low temperature as long as possible. When one refrigerator breaks down, the magnets
can be kept at 5 to 6 K with another refrigerator. At
the time of main power failure, a recovery compressor

driven by an emergency power source will recover theevaporated helium gas to the GHe buffer tank. We
will use no liquid nitrogen in this cryogenic system for
simplicity of the cooling system.
References
1) A. Goto et al.: RIKEN Accel. Prog. Rep. 31, 205 (1998).
2) T. Kubo et al.: RIKEN Accel. Prog. Rep. 31, 210(1998).
3) T. Kawaguchi et al.: RIKEN Accel. Prog. Rep. 31, 212(1998).

209

RIKEN Accel. Prog. Rep. 31 (1998)

Design of a Prototype Sector Magnet for RIKENSuperconducting Ring Cyclotron
T. Kubo, T. Kawaguchi, H. Okuno, T. Mitsumoto, T. Tominaka, S. Fujishima, J.-W. Kim, Y. Tanaka,
K. Ikegami, N. Sakamoto, S. Yokouchi, T. Morikawa, A. Goto, and Y. Yano
A superconducting ring cyclotron named SRC is tobe built in the RIKEN RI-Beam Factory project as
one of the post accelerators of the existing K540 Ring
Cyclotron.1,2) The SRC is designed to have a K-valueof 2500 MeV, consisting of six superconducting sector
magnets. The design of SRC is described elsewhere inthis progress report. 3 ,4)A full-scale model of the superconducting sector
magnet is to be built as a prototype sector magnet,in order to make sure the design of sector magnet isvalid under the condition as close to the real one aspossible. If this prototype magnet is successful, weplan to use it as one of the sector magnets of SRC.
The design of the magnet has been outlined in the last
year's progress report. S ) Here, we report on progressin the design as well as on status of fabrication.
Figure 1 shows a schematic drawing of the sector
magnet. The huge electromagnetic force 6 ) exerted on
the main coils is supported by means of what we callcold-pole method. The pole pieces are separated fromthe iron return yoke and are cooled down together withthe main coils in a cryostat. Two coil vessels accom-

7400mm--!

Fig. 1. Schematic drawing of the prototype sector magnet:a side view (upper figure); a top view (lower figure).

210

modating the main coils are attached to the side of
the upper and lower pole pieces, which are linked eachother by pole links. This arrangement allows the polepieces to work as mechanical supports against the electromagnetic force.
The cold mass, consisting of the cold poles, main
coils and main-coil vessels, is supported by support
links shown in Fig. 1. The eight vertical links (fourlinks in each of the upper and lower side) support theweight of cold mass, while the four horizontal links(two links for each of the upper pole and lower pole)
support the force that shifts the cold mass toward theside yoke.
Some details of the main coil vessel and cold poleare shown in Fig. 2. One of the important issues inthe design of sector magnet is how to fix the coil vesselto the side of pole piece. Two kinds of schemes that
we proposed are shown in Fig. 3. In the scheme shownby the upper figure, a sort of "hook" is used to fix thecoil vessel to the pole. The coil vessel and the "hook"
are assembled by welding. The second scheme shownby the lower figure in Fig. 3 uses screws to fix the coilvessel to the pole as well as to assemble the coil vessel.
In the prototype magnet, we adopt the former scheme
for the upper coil while the latter one for the lower
coil, and plan to examine through the test operationof prototype magnet which scheme is better.
The design of main coil vessel was made estimating
the stress caused by the electromagnetic force and thermal contraction. The material of coil vessel was chosen
to be a stainless steel called SUS316L by considering
its strength. The wall thickness of coil vessel was determined so that the estimated maximum stress does
not exceed the allowable maximum stress of SUS316L.

Fig. 2. Some details of the main coil and cold pole.

Welding

M d O PI

Coil Vessel- -. _,!, - ""! - - - - \Main Coil- - -- - -- - - - - - ---Pole

Fig. 3. Two kinds of schemes to fix the coil vessel to thecold pole.

The size and interval of screws were determined in thesame way. The material of screws was chosen to bea stainless steel called A286. The displacement of themain-coil vessel due to the electromagnetic force wassimulated to be about 1.1 mm in the horizontal direction and about 1.9 mm in the vertical direction at
maximum. The fatigue limit was also checked for thecoil vessel, welding spots of coil vessel, and screws. It
is found that no breaks are expected for the assumed
cycles of 10,000 (1 cycle/day for 30 years). Fabricationof the cold pole and coil vessel has started.
An aluminum-stabilized superconductor, designed
based on Maddock's criterion, is used for the main coil.
The details of the conductor are given in Ref. 5 alongwith those of the main-coil configuration. Fabricationof the conductor finished in the spring of 1997. The
conductor specification was checked by testing several
samples of conductor, and was found to be achieved.
Heat transfer from the Al stabilizer to liquid Helium
was measured using a setup simulating the main-coilconfiguration. It was found that the measured heattransfer was large enough to achieve the design valueof maximum stabilized current. The measurements ofmechanical properties, such as stress-strain curve, fatigue, and creep, were also made using sample piecesof the conductor. It was found that the conductor wasstrong enough against the electromagnetic force andthermal contraction.
Model trim coils, which correspond to a part of real
trim coils, are to be fabricated and installed in thepole gap space as shown in Fig. 1. The conductor oftrim coil has been designed to be cryogenically stable,
based on Stekly's criterion. It is a rectangular conductor whose cross-sectional sizes are horizontally 2.9 mm
and vertically 3.6 mm, consisting of a stabilizer housingof pure aluminum and a superconducting wire at thecenter of conductor. The superconducting wire is thesame to the wire that constitutes the Rutherford-type
cable used for the main-coil conductor. 5 ) The coolinggaps of trim coil are taken to be 0.25 mm. The cooling efficiency is estimated to be 40% considering thespacers placed in the gaps. The trim coil is expected
to be stable up to 550 A at 6 T. We plan to excite itwith currents lower than 500 A for safety. The current
density at 500 A is estimated to be about 41 Ajmm2 .
The trim coil vessel is connected in series to the main
coil vessel, so that the trim coil can be cooled by theliquid helium provided by a common refrigerator.
Fabrication of the trim-coil conductor finished also
in the spring of 1997. Its specification was checked forseveral samples, and was found to be achieved. Heattransfer measurement of the Al stabilizer was madesimilarly to the main coil conductor, and a designed
value of heat transfer was confirmed.
The maximum stabilized currents were measured ina realistic condition both for the main coil and trim
coil conductors. A small test magnet was built forthis purpose. The results are given elsewhere in thisprogress report. 7 )The fabrication of prototype magnet is progressing.
The coil winding starts in March 1998. The cold massand cryostat will be completed in the summer of 1998.
References
1) Y. Yano: RIKEN Accel. Prog. Rep. 31, 181 (1998).
2) A. Goto et al.: RIKEN Accel. Prog. Rep. 31, 205 (1998).
3) T. Mitsumoto et al.: RIKEN Accel. Prog. Rep. 31, 206(1998).
4) T. Kawaguchi et al: RIKEN Accel. Prog. Rep. 31, 208(1998).
5) T. Kubo et al: RIKEN Accel. Prog. Rep. 30, 201 (1997).
6) T. Kawaguchi et al: RIKEN Accel. Prog. Rep. 30, 199(1997).
7) T. Kawaguchi et al: RIKEN Accel. Prog. Rep. 31, 212(1998).

211

RIKEN Accel. Prog. Rep. 31 (1998)

Quench Stabilities of the Superconducting Wires for the Sector
Magnets of RIKEN Superconducting Ring Cyclotron
T. Kawaguchi , H. Okuno, A. Goto, and Y. Yano
In this paper, results of numerical and experimental
studies on the quench stabilities of the superconducting coils are described. The quench stabilizing currentsof the main and trim superconducting coils were confirmed from this work. Hence, we have begun to wind
the coil of the prototype magnet .
Sector magnet s l ) for the proposed superconducting ring cyclotron (SRC)2) of the RIKEN RI beamfactory project require two kinds of superconducting
coils: ' main and trim coils. Table 1 shows the parameters of the wire for these coils. The wires forthe above-mensioned prototype magnet 3 ) were alreadypurchased. One of our basic design concepts for thesector magnets is to make quench-free superconducting coils to assure the reliable long-period operation of
the SRC. For this purpose, we planned to use partial stabilization criteria (Maddock's stabilization 4 ))for the main coil, and full stabilization one (Stekly's
stabilization 5 )) for the trim coil. The partial stabilization criterion is defined as follows : when a normalconducting state happens in some part of coils due tothe mechanical disturbance, the superconducting state
can be recovered within a few seconds with the coolingby liquid helium (LHe). On the other hand, the fullstabilization one is: even when the entire part of coils
was turned into the normal-conducting state the superconducting state can be recovered immediately by
LHe cooling. Although the full stabilization design ismuch safer than the partial one, it requires the lower
current density coils. Therefore, we can not use thismethod to the main coils. However, for the trim coils it
is hard to fix the coil windings in mechanically strong
manner because of their configurations. We have thus
decided to use the full stabilization criteria for the trim
coils.
Table 1. Parameters of two superconducting wires.
Items

For main coil

For trim coil

Operation current (A)

5 0 0 05 0 0Max. magnetic field (T) 6
Stabilizing criterion..... ~5S0

c:riti(;~ cl1.~llt.(N ...

.... ..~ 1.I.S0

at6T,4.3K
2.9x3.6

Materials

NbTi / Cu / Al

NbTi/Cu/ AI

Section area ratio

1 / 1 / 17
~ SOO

1 /l /IS

0,2 %yield strength . .. ~Sof AI (kg/mm2)212~ 0 .003

30c--is 0 .002

t~mp .

g 0.001
o

0

o

0.2

0.4 O.STime (s)0.8

Fig. 1. Calculated voltage drop and maximum temperature of the test main coil.
1 000A,heat=4m.ltou=1 s
1200

0 .12

1000

0 .1

800

0 .08

c: SOO

~ 400

O.OS

200

0 .02

~

5 0%

40%

:>

c::
0

-is
CD

C)

.!
0 .04 "0

>

0

0
0

...........~4: ...

g···········1

CD

~

<.)

Outer dimension (mm) 8.0 x IS.0

Cooling surface ratio

40

o

Full

~~~il~zillgc\l~.llt(~.) . ~600Q
at 6 T, 4.5 K

RRR of Al

Current=5500A. Heating=SOWxO.2sf4Ocm
0 .004

6

Partial~ IIS00

Characteristics of the heat flux transport from thewires to LHe, and electric resistivities of the aluminumstabilizers of the wires , were measured in LHe at thewire manufacturer, Furukawa Electric Corporation.
Using these measured data, the stabilization currentsof the main and trim wires were calculated to be 6000
A and 750 A, respectively.
Next, we made a numerical calculation and an experimental study on the quench phenomena. The numerical calculation was done to understand the realtransient phenomena and to obtain the suitable specifications (capacity and arrangement) of electric heaters
and voltage taps for the experiment study. In Fig. 1,
the calculated results of the voltage drop and the temperature of the main coil at 5500 A are given as afunction of time. A pulsed heat loading of 60 W wasapplied to the wire over length of 0.4 m for 0.2 second.
As seen in Fig. 1, the voltage drop becomes zero 0.3
sec after the heating. Then we can say that the main
coil is stabilized against the quench at the excitation
current of 5500 A. Figure 2 shows the another calculated result to find the fully stabilizing current of thetrim coil. In this calculation, the normal-conducting
length was increased to 4 m at 1000 A, and then the

0.2

0 .4
O.S
Time(s)0.8

Fig. 2. Calculated voltage drop versus current of the test
trim coil.

coil current was decreased with a time constant of 1
second. As seen in Fig. 2, the decreasing gradient of
the calculated voltage drop suddenly changed toward
zero at 730 A, which can conclude that the fully stabilizing current of the trim coil is 730 A.
Experimental study has been done at Mitsubishi
Electric Corporation by using two small superconducting coils, a test main coil and a test trim coil, which
use same superconducting wires and similar coolingconfigurations as the prototype magnet. In these coils,
electric heaters were set on the wire surface to givea thermal disturbance instead of mechanical disturbance. The heating lengths are 0.4 m in the test main
coil's wire of 115 m , and 0.1 m in the test trim coil's 55
m. Figures 3 and 4 show a drawing and a photographof the three coils arrangement. The coils were cooled
down to 4.5 K using LHe, and the stabilizing currentsof the main and trim test-coils were measured under
the total magnetic field of 6 T: 4.5 T from the bias
coil and 1.5 T from the test main coil. Figures 5 and6 show the measured results on the main and trim
test-coils, which can be compared with Figs. 1 and 2.
The stabilizing currents obtained from the experimentwere 5700 A and 630 A for two coils, which are 1.14
and 1.26 times larger than the designed maximum operation currents of the main and trim coils. This hasverified the validity of our design on quench stability.
The difference between the calculated stabilizing current and measured one is thought due to the degradation of heat flux characteristics in real coils. It should
be noted that the high current feeding up to 6500 A tothe main superconducting wire was done for the firsttime in this experiment, because it was impossible tofeed such a high current during the wire inspection testat the wire manufacturer due to their power supply
limitation.
Current=5500A, Heating=33WxO.2s/45cm
0 .004 , - - - - , - - - - - , - - - , - - - - ,4~

0 .0033a.

0 .0022E0Bias coil

Test main coilU

Test trim coil

g
~

~

u

Q)

0 .001

Cl

2!
(5
>

CD

iii
Q)

0

0

-0.001
1.5

::t:

- 1
2
2 .5
Time (s)3Fig. 5. Measured voltage drop of the test main coil.

Trim 700A, Ir measurementd635mm800-.,.

Fig. 3. A drawing of three coils configuration.

g

600

r---

0.006

---

0.004

current

~

E 400
~

~

,,,"

()

"----- ---....

voltagE~a.
0 .002 ~
Q)

Cl

'\

o

200

[' - - -2!
>(5-0.002

0
16

18

22
20
Time (s)24

26

Fig. 6. Measured voltage drop versus current of the test
trim coil.

Fig. 4. An outward view photograph after three coils
assembly.

References
1) T. Kawaguchi et al.: RIKEN Accel. Prog. Rep. 31, 208(1998).
2) A. Goto et al.: RIKEN Accel. Prog. Rep. 31, 205 (1998).
3) T. Kubo et al. : RIKEN Accel. Prog. Rep. 31, 210(1998).
4) B. Maddock et al.: Cryogenics, Aug. 1969, pp. 261-273.
5) Z. Stekly et al.: IEEE Transaction NS-12, 1965, p. 367.

213

RIKEN Accel. Prog. Rep. 31 (1998)

Analysis of the Injection and Extraction Trajectories
in RIKEN Superconducting Ring Cyclotron
S. Fujishima, H. Okuno, T. Tominaka, T. Mitsumoto, T. Kubo, T. Kawaguchi, J.-W. Kim,
N. Sakamoto, A. Goto, and Y. Yano
In the RIKEN RI Beam Factory project, a six-sector
Superconducting Ring Cyclotron (SRC) has almost
been designed .1) The purpose of present analysis is to
optimize the layouts and specifications of the injection and extraction elements in the SRC. For the optimization, the differences of trajectories in the elements
and the required fields of the elements were minimized.
Beam envelopes were also studied to adjust the beamwidth.
The SRC has strong stray field from the sector
magnets,2) and this field strongly depends on the condition of acceleration. Thus, the trajectories of various beams differ considerably from each other. Besides, the injection and extraction elements should beinstalled in a small space limited with the sector magnets, RF -cavities, and vacuum chambers. These difficulties make the design of the injection and extraction
systems challenging. The injection system consists offour bending magnets (BMl, BM2, BM3, and BM4),
three magnetic inflection channels (MICl, MIC2 , andMIC3), and an electrostatic inflection channel (EIC).
The extraction system consists of a bending magnet(EBM) , three magnetic deflection channels (MDCl,
MDC2 , and MDC3) , and an electrostatic deflection
channel (EDC).3)
To analyze the injection and extraction trajectories
in the SRC, an equation of motion was solved with
Runge-Kutta-Gill method. Magnetic field of the sector
magnets used in this analysis was calculated with athree-dimensional coinputer code, "TaSCA".
Table 1 shows energies and magnetic rigidities oftypical two beams of 16 0 7 + and 238U58+. Between
these two beams, the difference of magnetic rigidities
becomes the maximum, so that the difference of trajectories also becomes the maximum. To minimize thebore of the elements, the difference of trajectories mustbe suppressed as small as possible. Length of eachelement was determined in consideration of the balance
between the difference of trajectories in the element
and the required field of the element.
Figure 1 shows schematic layout of the injection elements, and the injection trajectories of the typical two
beams. Table 2 shows specifications of the injection

Fig. 1. Schematic layout of the injection elements, andthe injection trajectories of the typical two beams.

Table 2. Specifications of the injection elements.
Table 1. Energies and magnetic rigidities of typical two
beams of 16 0 7 + and 238U58+.

16 0 7 +238 U 58+214

B p [Tm]

Energy [Me Vlu]
Inj.
Ext.

Inj.

Ext.

74.2
58.0

2.89
4.57

4.90
7.52

200
150

EIC
MIC1
MIC2
MIC3
BMI
BM2
BM3
BM4

Radius[em]

Angle[deg.]

Length[em]

BorE
maximum

1000----

variable
46.5
52.5
73.9
52.0
52.0
52.0
7.0

100
90
101
112
120
118
116
60

95 kV/em
0.18 T
0.27 T
1.5 T
4.02 T
3.92 T
3.96 T-0.8, +0.7 T

III
110
87
132
130.5
128
492.5

elements. The MIC3, BMl, BM2, BM3, and BM4 aresuperconducting.
Figure 2 shows difference of trajectories in the ErC.
The ErC should be movable in the radial direction by
10 cm and its radius of curvature should be adjustable,
because the gap between electrodes can be open 1 cm
at most. Figure 3 shows difference of trajectories in theBM4. To minimize the difference of trajectories, theBM4 generates not only positive field but also negativeone.

Figure 4 shows envelopes of the injected beam ofEmittance was assumed to be 10 mm mrad.
The envelopes can be adjusted with two gradient-fieldcoils built in the BM2 and BM3 additionaly.
Figure 5 shows schematic layouts of the extraction
elements, and the extraction trajectories of the typical two beams. Table 3 shows specifications of theextraction elements. The MDC3 and EBM are supercond ucting.
238U58+.

40

§

20

c:

0

:2

1607+

~

238 U 58+

0-

t\l

.s
::l

.5

20

~

40
- 335

-340

- 325

S30

-320

Radial position [em )Fig. 2. Difference of trajectories in the EIe.

E

495

Fig. 5. Schematic layout of the extraction elements, andthe extraction trajectories of the typical two beams.

~

"'~"
co

494

III

.s
.....

1607.+._____-~-..__

0~.....0493

to the BM3

Table 3. Specifications of the extraction elements.

~

c:

8

492

III

.s

E
0

<l::

BorE

Radius[em]

Angle[deg.]

Length[cm]

maximum

2000 . . . .
185
190
230
175

variable

199
103
106
120
159

100 kV/cm
0.2 T
0.3 T
1.12 T
3.9T

238 U 58+

49 1

III

~

is

490

224

226

228

222

Azimuth around the center of arc of the BM4 [degree)

Fig. 3. Difference of trajectories in the BM4.

EDC
MDCl
MDC2
MDC3
EBM

32.0
32.0
30.0
52.0

1.0

Layouts and specifications of the injection and extraction elements in the SRC have almost been optimized. Further optimization is in progress.

0.8

E

~

0 .6

oS

:9
~

.....

References

0 .4

(;l

X
0 .2
C

0 .0

0

RF

10

15

25

Length of the trajectory [m]1) A. Goto et al.: RIKEN Accel. Prog. Rep. 31, 205 (1998).
2) T. Mitsumoto et al.: RIKEN Accel. Prog. Rep. 31, 206(1998).
3) H. Okuno et al.: RIKEN Accel. Prog. Rep. 31, 216(1998).

Fig. 4. Envelopes of the injected beam of 238U58+ , adjusted with gradient-field-coils.

215

RIKEN Accel. Prog. Rep. 31 (1998)

Design Study of Injection System for RIKENSuperconducting Ring Cyclotron
H. Okuno, T. Tominaka, S. Fujishima, A. Goto, and Y. Yano
Superconducting magnets for the injection system
of Superconducting Ring Cyclotron (SRC),! ) are being designed. In this report, the characteristics andstructure of those magnets are given.
The injection beam transport system consists offour bending magnets (BM1, BM2, BM3, and BM4),
three magnetic inflection channels (MIC1, MIC2, andMIC3) , and an electrostatic inflection channel (EIC),
as shown in Fig. 1. Their specifications obtained fromnumerical analysis 2 ) are shown in Table 1. All of BM's
(BMl-4) and one of MIC's (MIC3) are required to besuperconducting magnets in order to produce required
strength of magnetic field. In the following section, we
describe about design study of the BM1 , which is anticipated to be the most difficult to construct with thesuperconducting elements.
There are three difficulties in designing the BM1.
Firstly, we can not use iron yokes for magnetic shielding because the total flux of the stray field in the cen-tral region of the SRC is so large that the ion yoke ofBM1 (if used) would be saturated. We should therefore
adopt active-shield type of magnets for the all BM's although the magnetic motive force is larger than thatin the case of an iron-shield type of magnet. Secondly,
the space available for the BM1 is very narrow: theBM1 has to be constructed in the space of about 20
cm in radial direction. In the coil-end region, bothcoil supports and cryostat walls have to be accommodated in the space of about 10 cm. Thirdly, the BM1
needs to be consisted of coils with negative curvature.
This means that it is difficult to wind cables, because
cables can not be wound with tension. Taking thesethree difficulties into account, we took cares of the following two points in the design of the BM1. Firstly,
the coil structures should be simple. Secondly, its fieldgenration should be as effective as possible: namely,
the size of the constituent coils in radial and azimuthal
directions should be as small as possible.
Here, we propose a new coil structure of the activeshield type. Figure 2 shows the cross section and the
3D-view of the coil structure. Eight current sheets
located closer to the beam axis generate the magnetic
field in the beam bore, and the rest four current sheets
generate the field to cancel the fringe field from theeight current sheets. Such configurations of the current
sheets can allow the structure of coils that does not
require a "bent up" at the ends of the channel.
Coil1

Cross Section

15

Generate
Field

II

Fig. 1. Schematic layout of the injection elements for the
SRC , and trajectories for injected beams.

~I -I' -I·: -lSIl

Table 1. Parameters of the injection elements.

ShieldFringe Field

EIC
MICI
MIC2
MIC3
BMI
BM2
BM3
BM4

216

Radius(cm)

Angle(deg.)

111
110
87
132
130
128
492.5

46.5
52.5
73.9
52.0
52.0
52.0
7.0

B or E (max.)(T) or (kV fcm)
95
0.18
0.27
1.5
4.02
3.92
3.96
-0.8, +0.7

Coil4

Fig. 2. Coil structure of the BM1.

The coil size and location were optimized by twodimensional analysis of the magnetic field. 3 ) Figure 3
shows a coil geometry and the performance which satisfies the specifications of the BM1.
Figure 4 shows the cross section of the coil support.
The coils are mainly supported in the horizontal and

Y[m]

0 .07
0 .06

By[T)
0.05
0.04

4.0

0.03

3.0

0.02

2.0

0.Q1

1.0

0.0

0.0

-0.01

-1.0

-0.02

-2.0

-0 .03

-3.0

-0.04

-4.0

Fig_ 3. Field distribution and coil geometry showing aquarter of the BM1.

the vertical directions by a pair of wall-to-wall clamps
and bolts, respectively. In the design of the coil support, it is important to keep the coils compressive during the excitation phase, in order to avoid a coil movement which causes quench of the coil. For this purpose, a pre-stress is applied to the coil by Cotta, Bolt!
and Bolt2 seen in Fig. 4. Its strength should be large
enough to compensate the shrink of the coils relative

to the coil supports during the cool-down and excitation phases. In cool-down, the coils and their supports shrink with different rates. The shrink rates aof the coils relative to the supports are shown in Table 2. In excitation, the magnetic forces deform thecoils and the supports. The ratios f3 of the shrink of
the coils and the deformation, of the supports relative
to the coil sizes are shown in Table 2. The pre-stress(J required during the assemble can be calculated by(J = E x (a + f3 - ,) where E represents the elastic
modulas of the coil assumed to be 20 MPa. As shownin Table 2, the values of (J are less than their typical values of the yield strengths which are 70 MPa for
the insulation of the coil. Further analysis and optimization of the support structure may decrease themaximum stress of the coil 3-6.
In summary, design study of the superconducting
magnets for the injection system of RIKEN SRC was
performed. It showed that difficulties of these magnets
could be overcome using a simple coil structure whichis easy to wind and support. Their full-scale models
will be made in the near future.
Table 2. Summary of structural analysis on the cross section of the support structure. See the text about thedefinition of the symbols in the table.

,

Q

(3

[10- 3 ][10- 3 ][10- 3 ]

[MPa]

V

-0.75
-1.50

-0.34
-0.25

0.84
0.58

-38.6
-16.6

Coil 3-6
H
V

-0.25
-1.50

-0.36
-0.00

1.73
1.84

-46.8
-66.8

Coil 1-2
H

0"1

References
Coil3(upper) & Coil4 (below)
Coil5(upper) & Coil6 (below)

Fig. 4. Cross section of the coil support structure.

1) A. Goto et al.: RIKEN Accel. Prog. Rep. 31, 205 (1998).
2) S. Fujishima et al.: RIKEN Accel. Prog. Rep. 31, 214(1998) .
3) T. Tominaka et al.: RIKEN Accel. Prog. Rep. 31, 218(1998).

217

RIKEN Accel. Prog. Rep. 31 (1998)

Optimization of the Superconducting Dipole Coils for Injection
System of RIKEN Superconducting Ring Cyclotron
T. Tominaka, H. Okuno, S. Fujishima, A. Goto, and Y. Yano
The injection system for the RIKEN 6-sector superconducting ring cyclotron (SRC) consists of four bending magnets (BMl, BM2, BM3, BM4), three magnetic
inflection channels (MICl, MIC2, MIC3), and an electrostatic inflection channel (EIC). Four of the bending magnets and one of the three magnetic inflection
channels are superconducting. An active-shield typemagnet which is equipped with a pair of shield coils, as
shown in Fig. 1, is adopted for these dipole magnets. 1,2)
In this report, optimization of the cross-sectional shapeof an active-shield type dipole magnet is described.

XO.O

X20.0

X40.0

I

1

1

X100.0_I

X120.0__J

X140.0_ _X160.01

mization is shown in Fig. 2. The region permitted
as the location for current-carrying blocks is divided
into small rectangular elements. The upper darker elements are reserved only for the main coil, while thelower elements are for both main and shield coils, constrained from the requirement of the final coil configuration. The current in each element is optimized by
LP in such a way that the field homogeneity within
the racetrack boundary (40 mm x 30 mm), shown by
the gray line in Fig. 2, is better than 0.1%, and thefringe field at x > 0.25 m, shown by a bullet in Fig.
2, is below 100 G. In this LP, the following objectivefunction and various constraints are expressed by linear function and inequalities,• objective function: total ampere turn,• constraint (1) : minimum central field,• constraint (2) : maximum current density,• constraint (3) : lowest field homogeneity,• constraint (4) : maximum fringe field,• constraint (5) : maximum difference of currents
between the lower main and shield blocks.

150

Fig. 1. Schematic view of the active-shield type dipole
magnet.

The superconducting dipole magnets are planned tobe composed of rectangular current-carrying blocks toease the coil fabrication. A procedure to optimize thecross sectional shape is studied here with following two
steps:3)(1) Rough optimization of the size and location of thecurrent-carrying blocks.
(2) Precise optimization of the locations of rectangularcurrent blocks.
As the first step of optimization, a linear programming (LP) method can be used to acquire the initial
cross sectional shapes for further optimization in thesecond step. In general , LP is effective to find theglobal minimum or maximum of any linear function
subject to a set of constraints defined by linear inequalities. On the other hand, as the second step, an
optimization method to find the local minima of arbitrary function is adopted. Then, the global minima of
this optimization problem is found by the combinationof these two steps.
A quarter of the cross-sectional geometry for opti218

x

200

250

(nun)

Fig. 2. Cross section of a magnetic inflection channelof the active shield type (MIC3), with the conductor(shaded) region for the linear programming.

As a result of LP, the current of each element isobtained, as shown with the darker element for thehigher current in Fig. 3. Then, the optimized current
distribution is approximated by two main rectangularcurrent blocks and one shield current block, as shownin Fig. 4. However, this conversion to the rectangularshape of current blocks induces a deviation from theoptimized arrangement in step 1.
As the second step which is a cross sectional position
optimization step, the horizontal and vertical displacements of each current block shown as (Xl, Yl), (X2' Y2),and (X3, Y3) in Fig. 4, corresponding to the coordinatesin Figs. 5 and 6 are optimized. The procedure of thesecond step is as follows: 4 ,5)(1) Calculation of the interior and exterior multipoles
determined from the cross sectional configuration ofcoil.
(2) Calculation of the field homogeneity from the interior multipoles and of the fringe field from the exteriorx(!!Un)

Fig. 3. Optimized cross section for obtaining Bo = 1.5 T,
showing the darker element for the higher current, withthe ampere turn, Itotal = 5.28 X 10 5 A (at jrnax = 150
A/mm 2 ).
l20r-------~----~--~._~

100 --- -____,--,----

I :~ uui::f!t:~;9;i-~··/:>,

40

20 ~ -------- ,--\ Shield Coil

22 \

33

150
x

200

(!!Un)

multipoles of dipole coils, and that between the fringe
field and the multipoles can be geometrically obtained
for the specific homogeneous regions like the racetrackand for the requirement of the fringe field. 5 ) Then,these relations are used for the calculation of the field
homogeneity and of the fringe field.
The optimal locations of each current block corresponding to the minimum value of the fraction to maximize the field homogeneity and the allowable fringe
field can be sought as the over lapped region of the two
contour plots, as shown in Figs. 5 and 6. In thesefigures, the darker region corresponds to the favorable
homogeneity (smaller value of the fraction) or the maximum fringe field, while the lighter region corresponds
to the less favorable homogeneity (larger value of thefraction) than the prescribed one.
As a result, the optimal coil configuration producing the interior field distribution shown by Fig. 7, andthe exterior field distribution shown by Fig. 8, can beobtained with the satisfaction of requirements by thisoptimization method.

Fig. 4. Cross section of a magnetic inflection channel ofactive shield type (MIC3) explaining the second optimization.

xxl (!!Un)

Fig. 5. Contour plot of (Xl, YI) plane, satisfying
I(By - Byo)/(Byo + 4)1 < 0.1%, with X2, Y2, X3, Y3 = O.

(!!Un)

Fig. 7. Homogeneous field region, satisfying I(By - Byo)/(Byo + 4)1 < 0.1%.

100
75
50

§: 25

0

:>.
III -25-50-750.250.50 . 751
xl.251.51.75

:2

(rn)

Fig. 8. Distribution of the fringe field, By, on the x axis(x> 0.25 m).
Fig. 6. Contour plot of (Xl, yd plane, satisfying
IBy(x> 0.25 m)1 < 100 G, with X2, Y2, X3, Y3 = O.
multipoles.
(3) Search for the optimal locations of each current block corresponding to the minimum value ofI(By - Byo) / (Byo + 4) I to maximize the field homogeneity with the constraint for the fringe field.
The relation between the field homogeneity and theReferences
1) C. R. Hoffmann et al.: Proc. 10th Int. Conf. on Cyclotron and their Applications, p. 222 (1984).
2) H. Okuno et al.: to be published in Proc. of 1997 Particle Accelerator Conf.
3) M. Kitamura et al.: IEEE Trans. Magn.-30, p. 2352
(1994).
4) T. Tominaka et al.: to be published in Proc. of 1997
Particle Accelerator Conf.
5) T. Tominaka et al.: Proc. 15th Magnet Technology
Conf. (MT-15, 1997); to be published.
219

RIKEN Accel. Prog. Rep. 31 (1998)

Numerical Study of Single-Turn Extraction for RIKENSuperconducting Ring Cyclotron
J.-W. Kim, T. Mitsumoto, A. Goto, H. Okuno, T. Kubo,
N. Sakamoto, and Y. Yano
The maximum beam power expected from the
RIKEN superconducting ring cyclotron (SRC) is very
high at the end of cyclotron acceleration. Hence, thebeam extraction should be carried out with near 100%efficiency in order to minimize the heating and radiation problems by stray beams. Separation of the final turn needs to be sufficiently larger than the radial beam-width for a perfect single-turn extraction.
However, the radial beam broadening due to resonancecrossing, space charge, and the other imperfections inoperation are not fully considered in the initial design
calculations.
A main design particle is 16 0 7 + accelerating from
128 MeV lu to 400 MeV lu because of its largest number of turns. For such light nuclei accelerating to
the highest design energy, the gain in orbital radiusby the final acceleration is much smaller than the
beam-width, so that other mechanism to enhance theturn separation needs to be employed. As empiricallydemonstrated on the RRC,1) an off-centered injection
scheme could be effectively used. The precession induced by an orbital off-centeredness can increase theseparation of the final turn. Figure 1 shows the motionof the radial phase ellipse during the last few turns of
the 16 0 7 + beam with emittance of 10 mm·mrad. The
pattern of precession is clearly visible. This is a casewith the precession amplitude of about 1 cm. A larger
turn separation by additional 2-3 mm seems to be obtainable by larger off-centeredness without notable distortion in the radial phase space, which may grant an
extra operation margin in the presence of unexpected
operational imperfections. The correct phase of precession at the time of extraction, on the other hand,
can be controlled by the cavity voltage.

-3 7.0 + - - - - ' - - - - - ' - - - - - ' - - - - - ' - - - - - ' - - - - - ' - -- - - ' - - - +

-37.5
::i

~ -38.0
xD-- 38.5-39.0 + - - , - - - , - - - , - - - , _ _ - - . - - - . - - - . - - - - 1 497.5 498 .0 498.5 499.0 499.5 500.0 500.5 501.0 5015
R (e m)Fig. 1. Precession of radial phase ellipse for 16 0 7 + accelerating up to 400 MeV / u before extraction. P x is theradial momentum in cyclotron units (c.u.). That is, thevalue of momentum is divided by moc (where mo is theion rest mass) and multiplied by a length unit a == c/wo.
220

The final turn is clearly separated at the entranceof the electrostatic deflector channel (EDC) as seen in
Fig. 1. Interference was next checked against previous
turns along the EDC, as shown in Fig. 2, because of
its long length (2 m). The pattern of turn separation
is well conserved along the EDC. The effect of EDC's
electric field is not included in the calculation, however.
Hence, the actual last-turn separation is much larger
as the beam is deflected by the EDC whose gap isdesigned to be 10 mm.

509+-~~, ~r~ --~--~-~--_7#~~--+

507

E'505

~ 503

501
~o 499if)

Cl:: 497

495

11'l
' "

11'l

,'\\

#'l

'~\.,

/A'l
\': "
//'/
" ", ~_ f/{~:-:"'.-""'--.:::-:::-=- /\.
EDC - - - - - - - - - --493+. -~--~--,__-~--~-__+
160
165
145
150
155
140
135
Azimuth (degree)

Fig. 2. Beam orbits near the EDC for the final turns. The
last turn is plotted by the solid line, and the previous
turns by the dashed lines.
For a single turn extraction the radial beam-width
should be sharply defined. A flat-topping cavity which
operates at the third harmonic of the main rf frequency
will be used to flatten the top of sinusoidal rf waves.
At present we consider to employ a flat-topping cavity which does not cover the inner few turns to savesome space for other cyclotron elements, as have been
adopted for the PSI proton ring cyclotron in Switzerland. That case is shown in Fig. 3 together with thecase of a full radial coverage by the flat-topping cavity.
Off-centered injection is not included in these calculations. Asymmetry in the phase acceptance can be seen
when the radial coverage is not full. Additional distortion seems to occur under off-centering, but this result
is not yet definite because of the uncertainty involved
in describing rf electric fields at the inner radial end of
the flat-topping cavity.
There are several mechanisms which can broaden theradial beam-width during acceleration. One serious
process of such comes from the space charge effect. It
is however not easy to implement this effect into theorbit tracking code. Instead, if using a simple analytic
expression in Ref. 2, the limiting current for 16 0 7 + isfound to be around 25 /-LA for the phase width of 20°,450 turns, and rf voltage of 550 ke V on three single-gap
cavities.

499 .0 -j-----'----'--'------'----'-+

u 498.5ow-0 498 .0

1-- - - -.......

cr 49 7.5

497 .0 +-~~-~~~-+
60 70 80 90 100 110 120
rf> ;(d egr ee )radial beam spread for ions which cross the liT = 1.5(=3/2) resonance. A small magnitude of the third
harmonic gradient appears to deteriorate the radialphase space. Figure 4 shows a case when the gradient is 1 gauss/cm. The crossing of the resonance bandis clearly displayed. The first harmonic component
also affects the radial phase space when crossing theliT = 1.5 resonance, but its tolerance level is higher.

3+-_J-_~

Fig. 3. The phase acceptance when employing a third
harmonic flat-topping cavity. The plot is for the last
turn prior to extraction. The solid line indicates thecase of a full radial coverage by the flat-topping cavity,
while the dashed line for the case of a partial radial
coverage beyond r = 380 cm.

__~__- L_ _- L_ _~-+_ _~ _ _

-:01
o

10

-2

A chief assumption on this limit in beam current isthat the radial beam spread allowed is a half of theradial gain by acceleration. This limit , however, is
not strictly applicable to the SRC since the final turnseparation is mainly determined by precession. In addition, the space charge broadening could be partiallycompensated, for instance , by controlling t he relative
rf phase between the main and fiat-topping cavities. In
reality, an accurate evaluat ion of the limiting current iscomplicated as space charge and its correction schemes
are involved. Since the beam-width increase may be inevitable in high current operation, its additional 1-2
mm increase needs to be acceptable in design.
Another serious condition is placed in reducing the-3+---~--~--~--~--~--~--~---+

445

450

455

460

465
4 70
R (em)

4 75

480

485

Fig. 4. The radial phase space motion when the 16 0 7 +beam crosses the lIr = 1.5 resonance. The plot is madeevery five turn. P x is the radial divergence, which isdifferent from P x defined in Fig. 1.
Further simulation of beam extraction is now under way, including the operational imperfections anticipated in the SRC.
References
1) Y. Yano: Proc. 8th Symp. on Accelerator Science andTechnology, p. 10 (1991).
2) W. Joho: SIN Report, No. TM-1l-4, Swiss (1968).

221

RIKEN Accel. Prog. Rep. 31 (1998)

Design of the RF Resonators for RIKENSuperconducting Ring Cyclotron
N. Sakamoto, o. Kamigaito, A. Goto, T. Mitsumoto, H. Okuno, and Y. Yano
For the RIKEN RI-Beam factory (RIBF) a new superconducting ring cyclotron (SRC)1) which consistsof six superconducting sector magnets, three acceleration radio frequency (rf) resonators, and one flattop resonator is planned to be constructed to provide
heavy ion beams whose energy range is from 60 to
400 MeV lu. The SRC requires acceleration radio frequency resonators having a wide frequency range from18 to 38 MHz with a harmonic number (h) of 6 andhaving a high acceleration voltage of a few MV Iturn.
For example, in the case of 16 0 7 + acceleration up to
the maximum energy of 400 MeV lu at the rf frequencyof 38 MHz (h = 6), an acceleration voltage of 2.4
MV Iturn is needed to obtain a turn separation larger
than 4 mm. Such a high voltage acceleration is also
helpful to depress the longitudinal emittance growthof high intensity beams because the space charge effect can be depressed by a high voltage acceleration.
Design study of the rf resonators for the SRC has
been made by using a three dimensional RF calculation
code, MAFIA.
The present design of the acceleration rf resonatorfor SRC is a single-gap type whose structure is basically same as that of RCNP Ring Cyclotron 2 ) (RCNPRC). The single-gap type resonator is suitable for the
narrow valley section of the 6-sector ring cyclotron
because its size is quite compact compared with the
double-gap type resonator. The RCNP-RC type acceleration resonator 2 ) has two main advantages. Firstly,
the shunt impedance and Q-value are large. Secondly, the wall power loss is small because no electricalsliding-contact is used. These advantages are vital forhigh power resonators.
A schematic view of the RCNP-RC type resonator
is shown in Fig. 1. The resonance is tuned by flapping the tuning panels. The resonances with the lowest

600

Fig. 1. Schematic view of the RCNP-RC type resonator.
222

and highest resonant frequencies are obtained when thepanel angle is horizontal (0°) and vertical (90°) , respectively. The lowest resonant frequency becomes lower
by enlarging the width of the tuning panel. However,
the resonant frequency of 18 MHz is hardly achieved
because there remains small space in the valley section.
Therefore, it is decided to adopt the double harmonic
number 12 instead of 6 for the low energy operation
so as to shift the frequency range from 18 to 23 MHz
to the range from 36 to 46 MHz. N ow the required
frequency becomes from 23 to 46 MHz.
MAFIA calculation for the resonant frequency of the
RCNP-RC resonator has been performed in order toknow how large is the difference between the resonant
frequency calculated and the one measured. The frequency range of the RCNP-RC rf resonator is from 30
to 52 MHz. It has turned out from the calculationthat while the highest resonant frequency of 52 MHz
is reproduced well, the calculated lowest frequency issmaller than the measured value by 8%.
A schematic drawing of the acceleration resonator isshown in Fig. 2. The frequency range obtained from
MAFIA calculation is from 21.6 to 47.6 MHz. The
shunt-impedance (Rs) and the Q-value (Q) for the tuning panel angles of 0° and 90° are shown in Table 1.
The values of Rs and Q at 38 MHz obtained by aninterpolation* are 1.4 Mf2 and 3 x 10 4 , respectively, sothat the net power required by the acceleration res4200rrun

r -____________________~I!,~--.-~::! ~Fig. 2. Schematic drawing of the acceleration resonator.
When the tuning panel angle is 0° , the open end of thetuning panel becomes very close to the wall in the opposite side, and a large electric field is produced between
the tuning panel and the wall. The size of the gap has
been set to be 60 mm which corresponds to 70% of theKilpatrick factor with the Dee voltage of V p = 300 k V.
It is known from the RCNP data that Rs and Q are roughly
proportional to the resonant frequency.

Table 1. Characteristics of the acceleration and flattop
resonators for SRC.
accelerat ion

parameters
Rs [MO]Q

flattop21.6{ 69) MHz

0.46

2.05

47.6(138) MHz

1.90

0.59

21.6{ 69) MHz

25000

32000

47.6(138) MHz

34000

27000

onator is roughly estimated to be 230 kW /resonatorat 38 MHz .
Installation of a flattop system by the third harmonic deceleration method is planned. In the caseof the double harmonic operation (h = 12), the flattop acceleration is essential because the phase acceptance becomes 50% smaller than that of h = 6 operation. The phase width 6.¢, which is defined by/V(6.¢) //V(¢ = 0) ~ 10- 4 , for the non-flattop accel·
eration and flattop acceleration are ±0.81° and ±7.3° ,respectively.
A schematic drawing of the present design of flattop
resonator is shown in Fig. 3. The resonant frequency ischanged by sliding the shorting plates. The frequency
range is set to be from 69 to 138 MHz and the deceleration voltage is 11 % of the acceleration voltage perturn.
The calculated electric field distribution along the
gap center for the acceleration and flattop resonators
are shown in Figs. 4(a) and 4(b) , respectively. Whilethe electric field of the acceleration resonator has amaximum at around the extraction region, the electricfield of the flattop resonator has a maximum at aroundthe middle of the De'e electrode. It is needed to see
the effectiveness of the present design of the flattop
system by calculating the acceleration orbits using the
calculated electric field distribution.
Characteristics of the rf resonators of the present
design are summarized in Table 2, and a proposed layout of the SRC is shown in Fig. 5. Three acceleration resonators and one flattop resonator are to be installed. Further investigation on the feasibility of ourrf system is now in progress. A test with a 1/5 scaled
model is planned to investigate the accuracy of the resonant frequency obtained from the model calculation
by MAFIA.
Table 2. Calculated values of shunt-impedance andQ-value.
parameters

acceleration

flattopnumber of unit

3

frequency [MHz]23~46

69~ 138

length [em]

420

355

height [em]

270

260

width [em]60(;0) , 120(0.')

35gap [mm]

250

100

aperture [mmxmm]±30 x 2480

±30 x 2180

tuner

flapping panel

shorting panel

tuner stroke

0° ~90°700 mmfeederinductive

inductive

Max. Vp [MV/gap]

0.88

0.10

Max. Power [kW /resonator]

230

7Fig. 3. Schematic drawing of the flattop resonator.
~

~

~ 0,6

47.6MH~Vj

10 0,5

i

·
··
··
··
··,
,
,

'0 0. 4..-I

Ql'.-10. 3
~

U

,
..
.

,..

.,

!

.~

~ Aper~ure ~U,,

21. 6 MH~

i

.., .
U

~
r..:l

1C< .... .. _• •"' " •• I11 • • •• I111 . ...

1000

2000

3000

rad ial position [rom ]
(a)

~ 0.4

Ql
-"' 0 . 3:

. .-1)..< 0.2::l 0.6
10 0.5acceleration resonator

~

..,

~

r..:l

,

-138 MH ~... · 103 MH~)..< 0 . 2~' '''' '''<:.'/~

6 9 MH ~I,

Fig. 5. Layout of the proposed SRC .

,:.o--Aperture~
1 000

2000

3000

r adial position [mm](b) flattop resonatorFig. 4. Electric field distribution along the gap center of
the acceleration and flat top resonators.

References
1) A. Goto et al.: Proc. 11th Symp. on Accelerator Scienceand Technology (Harima, 1997), p. 53.
2) T. Saito et al.: Proc. 12th Int. Conf. on Cyclotrons andtheir Applications (Berlin 1989), p. 201.

223

RIKEN Accel. Prog. Rep. 31 (1998)

Estimation of Beam Chamber Pressure Required for
RIKEN Superconducting Ring Cyclotron
K. Sugii, K. Ikegami, H. Okuno, S. Yokouchi, A. Goto, and Y. Yano
Beam transmissions are aimed to be above 99% for
all ion beams available in the RIKEN Superconducting
Ring Cyclotron (SRC).l) In a heavy-ion accelerator,
beam losses are mainly caused by a change of charge
state due to collisions of the beam against residual gas.
Electron stripping is especially serious in such a highercharge state heavy-ion accelerator like the SRC. Therefore, beam-chamber pressure is required to be as low
as possible in order to reduce beam losses. In this report the beam-chamber pressure required for the SRC
will be described.
A beam transmission (TJ) is given by
TJ = exp ( - No (JT f3 c t P) ,(1)

where No is the residual gas molecules per unit volume
at 1 Pa and is 2.5 x 10 14 molecules/cm 3 /Pa at 293 K ,(JT the charge-exchange cross section, f3 the ratio of ion
velocity to light velocity (c), t the accelerating time,and P the beam-chamber pressure. For a given crosssection and accelerating time, the beam transmission
can be obtained as a function of the beam-chamberpressure from Eq. (1).
Firstly, accelerating time of ion in a ring accelerator
can be estimated by the following equation:t ={(~E· A)/(~V· q)}. (hlf) ,(2)

w here ~E is the beam energy difference between theinjection and extraction, A the mass number, ~ V
the average of effective accelerating voltages per turnat the injection and extraction, q the charge number, h the harmonic number, and f the rf frequency.
The accelerating time of 238U58+ should be evaluated, since the charge-exchange cross section of highercharge state heavy ions such as 238U58+ is very large.
Table 1 shows the typical parameters of rf cavities for
238U58+. The accelerating time estimated from Eq. (2)using these parameters is 1.343 x 10- 4 sec.
Secondly, it is necessary to estimate the electronstripping cross section of fast heavy ions in collision

with residual gas molecules. In the case of the heavy
ions accelerated to a very high energy range, there arefew published data of the charge-exchange cross section. In the National Superconducting Cyclotron Laboratory (NSCL), the cross sections calculated from theBetz-Schmelzer approximation 2 ) have been comparedwith published data. 3 ) According to the comparison of
the electron-stripping cross section, the approximation
with a correction factor of 5 has been adopted in thehigh energy range of the K1200 cyclotron at the NSCL.
When applying the above result to the SRC, we obtain
the electron-stripping cross section of 4 x 10- 18 cm 2
for 238U58+ at the injection energy 58.0 MeV Inucleon(see Table 1).
Finally, the beam transmission was calculated from
Eq. (1) substituting 1.343 x 10- 4 sec and 4 x 10- 18
cm 2 for t and (JT as a function of the beam-chamberpressure. Figure 1 shows the calculation results. As we
can see from this figure, the beam-chamber pressure isnecessary to be below 5 x 10- 6 Pa in order to achieve
the goal of 99% beam transmission.

0.8

0.6

~~ -,

""

i

i

i '''-''''-'''''!-'-f'''+'EI_ =*I=j::~:::f-f-r---~;--+-+-+-#i+----+--+--.;.-;. .;-~-++-+ . _-._...-._.

0.4 r-r-": 23S:U-=
58+:±±:t±::l==:±=:±:::11llttJ==uLtm
ii

T inj. = 58.0 MeV/nucleon•

0.2 ~ Text. = 150 MeV/nucleon. ......

c.........

·i·= 4 X W oo lS cm2

q
T

·

O
'+- ~ r-t-Httl
10.6
10-5

i

10-4

!

10.3

Pressure (pa)Fig. 1. Beam transmission of 238U58+ at the injection energy of 58.0 MeV/nucleon as a function of thebeam-chamber pressure.

Table 1. Typical parameters of rf cavities for 238U58+.
frequency (MHz)harmonic number
T inj . (MeV/nucleon)
T ext . (MeV/nucleon)
Vinj. (MV /turn)V ext . (MV /turn)

224

27.2

6
58.0
150
0.38
0.86

References
1) A. Goto et al. : RIKEN Accel. Prog. Rep. 31, 205 (1998).
2) E. Baron, M. Bajard, and Ch. Ricaud: Nucl. Instrum.
Methods Phys. Res. A 328, 177 (1993).
3) The K500 0 K1200 A Coupled Cyclotron Facility: NSCL
Rep., chap.4.4.3., p. 64 (July 1994).

RIKEN Accel. Prog. Rep. 31 (1998)

Design of Debuncher System in the Injection Line to
Accumulator Cooler Ring of MUSES
K. Ohtomo and T. Katayama
The momentum spread (!::J..p I p) of RI beams from thefragment separator (Big-RIPS) is relatively large. The
required RF voltage to capture them into the RF buckets at Accumulator Cooler Ring (ACR) is proportional
the square of !::J..p I p. The value reaches 600 kV provided
that !::J..plp equals ±0.5% and that the stacking efficiency is assured to be 80%.1) This voltage seems toohigh to realize with a ferrite-loaded RF cavity. Therefore, we are planning to install debuncher cavities in
the injection line just prior to the injection kicker.
Simulations were performed in 6-dimensional phasespaces. The relations among distance, debuncher RF
voltage required, phase, and momentum spread ofbeam are given by8¢ = 27r~ !::J..v(3)... v '(1)!::J..¢
OW=5¢!::J..W,(2)e Q V sin(h8¢) = !::J..W (1 !::J..¢(3).. ) ... h8¢ < ~A
27rL!::J..vlv
2'(3)
eQV= !::J..W (7r / 2 _ !::J..¢(3)... ) ... h8¢>~.
A
h8¢
27rL!::J..vlv
2(4)Here, W is equal to the sum of kinetic energy T and
rest-mass energy. !::J..¢ and !::J.. Ware the initial phaseand energy spreads, o¢ is a maximum phase difference
at debuncher, 8W is an energy spread at debuncher,
L is a distance between Big-RIPS and debuncher, (3)..
is an interval length between bunched beams, !::J..vlv isa velocity spread of beam, Q and A are charge andmass numbers, V is a voltage of debuncher, and h isa harmonic number of RF debuncher with respect to
the RF of SRC.
In the above equations, 8W is the minimum of energy spread after debunching. The phase spread at
debuncher is h8¢, and the most effective debunchingis expected when h8¢ = 90 degrees. In case h8¢ islarger than 90 degrees, over ranged particles can notreceive sufficient acceleration or deceleration forces.
The voltages required for 4 typical nuclei are listed
in Table 1. Here we assumed that the initial !::J..¢ and!::J..plp are ±5 degrees and ±0.5%, respectively. The
bunch interval (3).. is 5.61 m. 8plp are momentum
spreads after debunchers. The reason why the harmonic number is different for the uranium (U) fromothers is due to the difficulty to produce a long-range
frequency-variable debuncher cavity.

Table 1. Beam parameters and debuncher RF voltage.
Nuclei:
Q/A
T[MeV/u]~p/p[%]~v/v[%]~W[MeV/u]Jreq[MHz]hhJreq[MHz]~q)[deg]h~q)[deg]h8q)L=8om[deg]h8q)L=10om[deg]8WL=80m[MeV/u]
8WL=100m[MeV/u](8p/p) L=80m[%](8p/p) L=100m[%]
VL=80m[MV]VL=100m [MV]

C

Cu

Sn

6/12
400
±0.5
0.2447
3.40
38.17

29/63
300
±0.5
0.28602.64
34.94
6
209.63
±5
30
88.0
110.0
0.90
0.72
0.17
0.14
3.78
3.13

50/132200±0.5
0.33881.82
30.32
6181.93
±5
30
104.2
130.3
0.52
0.42
0.14
0.12
2.77
2.21

6
229.02
±5
30
75.3
94.1
1.35
1.08
0.20
0.16
4.23
4.34

U
92/238100±0.50.40770.95
22.94
7160.59
±5
35
146.3
182.9
0.23
0.18
0.12
0.09
0.92
0.74

Numerical simulations have been performed by
a 6-dimensional phase spaces beam tracking code,
TRACEP. 2 ) The result is shown in Fig. 1.
Though the carbon particles are almost debunched,
the some of uranium particle spill out of the acceptableenergy width of ACR cavity. The loss ratios are about
8 and 13% when the debuncher is located at L = 80
and 100 m, respectively. This loss is inevitable whena same debuncher cavity is used for the particles withdifferent energy spread. It is concluded that the distance L should be about 80 m and that the maximum
RF voltage required for debunching is 4.2 MV.
The debuncher cavity has to have a wide tunablefrequency range. When the beam energy is between
80 to 120 MeV lu, the RF frequency of debuncher is 7times higher than that of SRC. For much lower beamenergy, the RF frequency of debuncher should be 8times higher than that of SRC. The total frequency
width ranges from 144 to 230 MHz.
As mentioned previously, the higher voltage is required for the higher frequency. It suggests that theresonant frequency should be changed by capacitancebecause shunt impedance is proportional to the capacitance to the minus one half power, and the larger the
shunt impedance the smaller the dissipation power.
A type of debuncher cavities is are-entrant ).../2 push
pull. The structure is cylindrical with a sliding nose forfrequency tunability. Diameters of the inner duct andof the beam bore are assumed to be 180 and 60 mm,
respectively. The nose surface to form gap is cut spher225

400MeV/u 12C 6+lOOMeV/u 238lf2+

Initial distribution at Big-RIPS

0.6

0.6,----.---,----.--~-~

0.3

0.3

~ 0.0

0.0

~
·0.3

-0.3

-D.6

-20

·10

·0.6
-10
10
10
20
·20
Distribution at a debuncher 80m away from Big-RIPS
0.6

0.3

~ 0.0+--':...l.. ....
- . ~"'_

0.0~·0.3+---+--f----f----l-0.3·0.6-i------+--+-...---I-~

·0.6
-20

·20

20

·10

10

·10

10

20

Distribution at a debuncher 100m away from Big-RIPS
0.6

0.6

0.3+---+--f----f----l

~ 0.0

0.3

.~ b....

0.0

-""

~

-O.3+---+--+--I~~

·0.3

·0.6
·20

-0.6
-20

-10

10
PHASE [deg)

20

·10

~~
10

20

PHASE [deg)Fig. 1. Beam filamentation in ¢- W plane. Left column displays carbon, while the right one displays uranium. Debuncher voltages are 4.2 and 0.9 MV, respectively. Top
figures show particle distributions at Big-RIPS, middle figures show distributions after a debuncher located
80 m away from Big-RIPS, bottom figures show distributions after a debuncher located 100 m away from
Big-RIPS.

ically so as to reduce electric field and chance of sparking. Low dissipation power and compactness of cavity
are of great importance to the design. Calculations for
optimizing the cavity diameter and length along thebeam path were done by SUPERFISH at the maximum
resonant frequency. The electric field is normalized insuch a way that the gap voltage including transit time
factor (TTF) is 1 MV.
The optimal length of cavity is turned to be 500 mm
and the diameter of cavity is 800 mm. A quarter crosssection of the optimized cavity computed by SUPERFISH is shown in Fig. 2. Parameters of the debuncher
cavity for typical nuclei are listed in Table 2. Here,the number of cavity is assumed to be 5 so that thepower dissipation should not exceed 80 k W per cavity.
The reason of the power limit is due to the assumption to use a tetrode: RS2058 made by SIEMENS. This
tetrode shows a good performance with the frequency
range up to 230 MHz though the anode dissipation
power is limited by 100 kW for pulse operation. The
gap distance is 54 mm at the minimum resonant frequency of 144 MHz.
Each debuncher cavity has a series of RF amplifiersystem, which consists of tetrode power amplifier, solid
226

Fig. 2. Cross section of cavity and distribution of RF
field by SUPERFISH numerical code. The left cavity isresonant at the maximum frequency (230 MHz) corresponding to 400 MeV /u of carbon, while the right one
is resonant at 160 MHz, corresponding to 100 MeV /u ofuranium. Both have coaxial symmetry line at each bottom boundary and have mirror symmetry line at eachleft boundary.
Table 2. Debuncher cavity parameters (for one cavity).
NucleiT [MeV/u]d gap [mm]freq [MHz]Veff [MV]TTF
Q-value
Power [kW]Rshunt [MO]Kilpatrick value

C
400
230
229.02
1.0
0.869
41400
79.3
17.0
0.631

Cu
300
180
209.63
0.8
0.913
37900
54.1
14.5
0.588

Sn
200
116
181.93
0.6
0.954
33900
35.5
11.4

0.597

U
100
76
160.59
0.2
0.961
31300
4.7
9.3
0.272

state pre-amplifier, and low level circuits. RF power
is delivered with 1% duty cycle. The tetrode amplifier requires the anode, screen grid, control grid, andfilament DC power supplies. The low level circuit includes modules of phase shifter, amplitude feedback
loop, and fine tuning loop. Expected power consumption is 32 kVA for one debuncher and the total becomesup to 160 kVA.
In conclusion, the designed debuncher cavity has awide tunable range of 144-230 MHz by moving the gap
nose. The maximum voltage reaches to 1.15 MV per
cavity when the resonant frequency is 230 MHz. The
required total RF voltage for debunching is 4.3 MV.
The five series of debuncher cavity system is requiredin order to reduce the momentum spread from ±0.5 to±0.15% which is the acceptable level of capturing by
RF bucket of ACR cavity.
References
1) Y. J. Yuan et al.: Proc. Eur. Part. Accel. Conf. p. 1338
(1996).
2) S. Yamada: (Program manual; TRACEP', NIRS internal report (1990).

RIKEN Accel. Prog. Rep. 31 (1998)

Study of Stochastic Cooling at Accumulator
Cooler Ring of MUSES
N. Inabe, K. Yoshida, M. Wakasugi, and T. Katayama
One of purposes for the accumulator cooler ring 1)(ACR) at the MUSES project 2) is cooling of ion beams
including the radio-isotope (RI) beam produced byprojectile-fragmentation in the Big-RIPS. Due to its
production mechanism the RI beam has a large emittance (cx: horizontal, Cy: vertical) and momentum
spread(~p/p). Moreover, due to the multi-turn injection, Cx of the beam injected into the ACR is verylarge. In the ACR the initial values of cx, Cy and ~p/p
are 125 7r mm·mrad, 10 7r mm·mrad, and ±0.15%, respectively. Requirement of cooling in the ACR is tohave a very fast cooling time for the RI beam because
the RI has an intrinsic life time.
Stochastic cooling3) is one of useful methods for cooling of ion beams. In particular, a fast cooling time ispossible by the stochastic cooling in a region of large
cx, Cy and ~p/p. On the other hand, in a region ofsmall cx, Cy and ~p/p, the cooling time of the stochastic cooling is longer than that of electron cooling. Consequently the stochastic cooling will be used as precooling that reduces the cx, Cy and ~p/p to about
10% of their initial values. After pre-cooling the electron cooling will be used to make the final values of cx,
Cy and ~p/p small.
We have calculated the transverse and longitudinalcooling times of the stochastic cooling in several conditions. From these results availability of stochastic
cooling was also investigated.
The transversal cooling time of the stochastic cooling is given by,4)

1 W{ -gl .

-T = - N-

sm~1L

12}

+ -glF
2

(1)

where
W : band-width of a feed back system
N : total number of particles~IL : phase advance between pickup and kicker
gl : = gJ/3p/3k, where g is gain of a feed back system and /3p and /3k are /3 values of pick-up and kicker ,respectively.
F : = M + U, M is the mixing factor and U is thenoise factor given: (noise of system) divided by (beamnoise per Schottoky band).
Using Eq. (1) , we calculated an optimum power of anamplifier to obtain the minimum cooling time. The
obtained power is very large (more than 1 MW for
N = 106 ). Because this power is too large to realize,
we have limited the power of the amplifier to be 10
kW.
We calculated the cooling times for 11 Be4 + (400
MeV lu), 39Ca20 + (300 MeV lu), 13 2Sn50+ (200

MeV lu), and 2ooPb8o+ (100 MeV lu) with ~p/p±0.15% and Cx = 100 7r mm·mrad. In the calculation
we assumed that temperature of a pickup (Tn) is 20
K, band width of an amplifier (W) is 2 GHz and coupling impedance of pickup (Zp) is 100 n. The otherparameters of the ACR are shown in Ref. 1.
In Fig. 1 the results are shown. The obtained coolingtime is less than 0.1 s for the particle number 103 '" 107of RI beam. In particular for the beam with a highcharge state the cooling time is very fast.

.!o

10

······· i···1···· ·· .. ..

r ········L......... , .......; ....

f···········:··.........-· ..·...... L .... ..... ....... .

j

·8
~

b.O

.5

oo

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

0.1

0 .01

U
0.001

J:-,,~Be~4.--!-_ _+ .._.~_--;-~

:

.j/,

:

:

: ..-~

:

.

1

:

l

~

l

~

1

~;;:±~I• ••• I• • • • • I• • • •••I• •• •Number of Particles
Fig. 1. Transversal cooling time.

We also studied longitudinal cooling time by a notch
filter method 5) which cooling is done in a region ofdispersion free. Similar to the transversal cooling, thecooling time of the longitudinal cooling is limited byoutput power of the amplifier.
We calculated particle number dependence of thecooling time. Kinds of particles and conditions are thesame as those used in the transversal cooling. In Fig.
2 results are shown. For number of particles ~ 107 theobtained cooling times are less than 0.1 s. In particular the cooling time of the particle with high charge
state is very fast. These tendencies are similar to thetransversal cooling.
We have also calculated the cooling times for several
values of the temperatures of a pickup system (Tn)and of the coupling impedances (Zp). Figures 3 and4 show Tn and Zp dependences, respectively. In both
calculations we assumed the number of particles 105.
For calculation of Tn dependence we assumed Zp =100 n and for that of Zp dependence, Tn = 20 K. As
shown in Fig. 3 the Tn dependence is weak. Coolingtimes of highly charged beams are shorter than 0.01 seven in 100 K. In the case of highly charged beams,

227

1.4+\

\J

~
o

e

E=

0.1

••••••••• , •••••••••• [ ; •••••• ,_ •••

00

.S
'0
o

u

ll

0.01

·+ :

ee

!
:

:
:
:

:

;t• :~• • • • •.
i/'i r':': ~:,:~~;[~.;~.;.~>,v

. ..

:

:
:

.;

~

:
:

0 .0>

j

i

!

j

----------,- ':::~~f~~~.c-.~.~I~._~,

Fig. 2. Longitudinal cooling time.

o

e

.~

00

.S

'0
o

U

0 .00 1 L-...L~~.L......-..4--'---'---'--'--'-____'_-L-'---'---,-....l....-~~
o
20
40
60
80
100

Temperature [K]Fig. 3. Tn dependence of cooling time, where, number ofparticles is 105 .
signal-to-noise ratio is good because voltage induced
at the pickup is much larger than that by noise. As
shown in Fig. 4, Zp dependence is strong, especiallyfor the region below 50 n. To obtain T < 0.1 s, Zp isrequired to be Zp > 50 n.

'--'-____'_-'---'-_L~~--'--L.....o...____'_-'---'-_L~---'--.........Jai

Number of Particles

228

I+ ..... .... , ........ , ......... .
0 .001l~80+ i:... .....

--:

~

:

:

~~.. ... ' .. .... ... .l.. .............. .

0 .1

e

j••••••••••

:

50

100

150

200

Fig. 4. Zp dependence of cooling time, where, number ofparticles is 105 .
From calculations we found fast cooling times in almost whole region. This indicates that the stochastic
cooling is advantage for the RI beam in ACR.
One of the important things to design a system of thestochastic cooling in ACR is to make a pickup systemwith a large coupling impedance. The large coupling
impedance is also important to reduce a needed gain of
the amplifier because the pickup voltage itself is large.
On the other hand it is not necessary for the pickup
system to have very low temperature. This makes construction of the system easy.
Based on the calculation we are designing a pickup
system with high coupling impedance.
References
1) K. Ohtomo et al.: Proc. 17th PAC, Vancouver, May
1997; to be published.
2) T. Katayama et al.: Proc. STORl 96, September 1996,
Bernkastel, Germany; to be published Nuclear Physics
A.

3) S. van der Meer: CERN report , CERN/lSR-PO/72-31(1978).
4) D. A. Goldberg et al.: LBL report , LBL-25924 (1989).
5) T. Katayama et al.: Particle Accelerators 21 , 99 (1987).

RIKEN Accel. Prog. Rep. 31 (1998)

Design of Booster Synchrotron for MUSES
T. Ohkawa and T. Katayama
The Booster Synchrotron Ring (BSR) is a partof Multi-USe Experimental Storage rings (MUSES).
The BSR functions exclusively for the acceleration of
ion and electron beams. The maximum acceleratingenergies are, for example: 3 Ge V for proton; 1.45
GeV /nucleon for light ions of q/A = 1/2; and 800
MeV /nucleon for heavy ions of q/A = 1/3. Electron
beam is accelerated to 2.5 GeV from the injection energy 300 MeV. I ) In this paper, results of lattice studyof the BSR are presented.
As shown in Fig. 1, the BSR consists of two arc sections and two long straight sections. Each arc section
is mirror symmetrical system against another, and contains two bending cells. Each bending cell is a dispersion suppressor arc, and consists of four FODO cells
because this number of cells is specified to raise thetransition 'Y ('Yt) sufficiently large. The dispersion in
the straight sections, other than the arc section, is zero.
The length of a dipole magnet of 1.911 m is determined by the circumference specification. The maximum magnetic field of a dipole (1.5 T) is determinedby the required maximum rigidity of 14.6 Tm. The lattice is specified by eight families of quadrupoles: QF1and QD1; QF4 and QD4 in the arcs, QF2 and QD2,QF3 and QD3 in the long straight sections. The structure of one FODO cell and short straight section in thearc are given as follows.

In this structure, d1 (d2) is 0.925 m (0.475 m) drift
space which are reserved for sextupole magnets forthe chromaticity correction and kicker magnets for theclosed orbit correction.
The two long straight sections are mirror symmetry structure each other. The lattice of each section(23.876 m) is
str1 = ~ QF2 ~ QD2 ~ QD3 d3 QF3d3

QD3 ~ QD2 ~ QF2 ~,where d s is a free space with a length of 4.276 m reserved for RF cavities, injection kickers or other devices.
Consequently, the whole lattice of BSR is describedas follows:
BSR = (arc, str1, arc, str1)
The parameters of the lattice are summarized in Table 1. The f3 and dispersion functions are shown in
Fig. 2. The 'Yt is 4.643 and the peak dispersion is3.730 m. The peak f3 function are 14.010 m in horizontal direction and 16404 m in vertical direction. 2 )The calculation is performed using the MAD program.
Table 1. Lattice parameter of BSR.

cel = QF1~B~QD1~B~

Circumferencec = 179.7159 m

str2 = QF4 ~ QD4 ~ QD4 ~ QF4

Average radius

R = 28.603 m

Max.. magnetic rigidity

Bp = 14.6 Tm

Then, the lattice of each arc section (60.365 m) is
arc = (cel, cel.cel, cel, str2, -cel, -cel, -cel, -cel)straight section A= 0.0458

Momentum compaction

Q

Transition gamma'Yt = 4.675

Betatron tune values

Qx/Qy = 6.691/6.212

Natural chromaticity

Q'x/Q'y = -8.670/ - 8.320

Max.. f3 amplitude

f3x/ f3y = 14.010 m/16.404 m

Max.. dispersion

Dx/Dy = 3.680 m/O.O m

QD4
QF4
QDl

Ion injection
electron extraction

20
straight section 8

Fig. 1. A layout of BSR.

40

60

80

ORBIT LENGTH(M)

Fig. 2. f3 and dispersion functions along the lattice.
229

The dynamic aperture might be seriously reduced
when chromaticity is corrected. This is because theaverage value of dispersion is lowered in a ring, corresponding to a high value of i't. In this lattice, the natural chromaticity values are -8.670 (horizontal) and-8.320 (vertical), and are corrected by two familiesof sextupoles SF and SD, (focusing and defocusing) ,associated with their respective qurdrupoles as indicated in Fig. 1. The phase advance between two sextupoles belonging to one family is 1r. The normalized
field strengths of sextupoles required to correct chromaticity are relatively large: 9.236 m- 3 for the SF
and -15.889 m - 3 for the SD . The tracking results using the beam with 1fc x = 1251f mm·mrad, 1fCy = 51f
mm·mrad, dp/p = 0 and fully corrected chromaticity,
are shown in Fig. 3. The largest initial betatron amplitude for which particles are still on a stable orbit isdefined as a dynamic aperture. The above tracking results show that the dynamic aperture of BSR is larger
than 1fC x = 1251f mm·mrad and 1fC y = 51f mm·mrad.
We estimate the relation between position of particle at the central momentum and tune values whenchromaticity is corrected. The results are shown in Table 2. It is found that the tune values of the particles
with large initial betatron amplitude are changed.

Next, we have calculated the tracking for the sevenparticles as shown in the Table 2 with fully corrected
chromaticity. In this case, all magnet elements are
misaligned (misalignment is ±100 /-lm and rotational
misalignment is ±0.1 mrad) , and field error (sextupole component of dipole magnet is -0.1 m- 3 ) is
introduced randomly. The above magnitudes of misalignment and field error are typical. Tracking results are shown in Fig. 4. It is found that the dynamic aperture of BSR is as large as 1fcx = 10001f
mm·mrad and 1fCy = 401f mm·mrad within the limit of
dp/p = ±10- 3 . For example, results of seven-particle
tracking with dp/p = 0 are shown in Fig. 5.
We have found that the dynamic aperture of BSR isapproximately eight times larger than the demanded
acceptance of 1fc x = 1251f mm·mrad and 1fCy = 51f
mm·mrad.
1 500 I:"I""'I""'I""I''T''''''-PT''W.......,......'''I'T~.....--....., 60~

50 ...-..

E 1000

40

S
§

S
30 §

]

~

~

500

20

e

tJ

10
PHASE SPACEPHASE SPACEREAL SPACEO .........~...............-.................~.................w~~~~[:~}~G... __

I...

__ -III

II.

... __

I

-2

-1

0

1

2

dp/p (%)
Fig. 4. dynamic aperture of BSR .

...

sr.-l

~

..-J

-3

PHASE SPACETRACKING

PHASE SPACEREAL SPACE"'~--~-~--~-~--~-~---_~---I~­
.",.

Jl~
I

____

S.

.",.

Fig. 3. Results of single-particle tracking (dp/p = 0).
Table 2. Relation between position of particle and tune
values (at dp/p = 0).

TRACKING

l_~~
o

_

_

_

_

1000

~. •
...
I
I J
J ~.. r.3jh.i!:.nO;I'!;I;;~
o

_

_

_

_

1000

",..

No.
1
2
3
4
5
6
7

230

ex
125
250
500
750
1000
1250
1500

ey

x

5
10
20
30
40
50
60

17.5 4.36
24.8 6.16
35.0 8.71
42.9 10.7
49.5 12.3
55.4 13.8
60.7 15.1

y

Qx

Qy

6.694
6.697
6.703
6.710
6.718
6.728
6.738

6.184
6.167
6.134
6.097
6.052
6.000
5.948

Fig. 5. Results of seven-particle tracking (dp/p = 0).

References
1) T. Katayama et al.: Proc. 17th EPAC (Sitges, 1996), p.
563.

2) T. Ohkawa et al.: Proc. 17th PAC (Vancouver, 1997).

RIKEN Accel. Prog. Rep. 31 (1998)

Design of Slow Extraction System at Booster
Synchrotron for MUSES ·T. Ohkawa and T. Katayama
In booster synchrotron ring (BSR) the accelerated
ion and electron beams will be fast extracted andsubsequently injected into the Double Storage Rings(DSR) by one turn injection mode. As another operation mode, ion beams will be slowly extracted from
BSR for the experiments. In this paper, injection andextraction (especially slow extraction) procedures of
the BSR are presented.
Arrangements of the injection and extraction magnets are shown in Figs. 1 and 2. The BSR lattice isdesigned to be able to operate with two different extraction modes for ion beams: fast and slow extractions.

As seen in Fig. 1, an electrostatic septum (ES), four
septum magnets (SM1, SM2, SM3, SM4) and threebump magnets (BM1) are used for the electron beam
multi-turn injection. These magnets, except bumpmagnets, are used for the ion-beam slow extraction
which is carried out by using a third order resonance(vres = 20/3).
As seen in Fig. 2, three septum magnets (SM2, SM3,
SM5), four bump magnets (BM2, BM3) and ten kicker
magnets (K1) are used for the ion-beam one turn injection. These magnets are also used for electron-beam
fast extraction. The ion beam from the ACR is injected
into BSR through the septum magnet SM5, SM3 and- I o n beam
- - electron beam

QFI

QF2

Ion slow extraction

ES

SMI

~"""OO . SM2

OF'

QF3

Fig. 1. An arrangement of straight section A.

- I o n beamelectron beam

BM3

/s!

QF2 Q 0 2 1 1 Z
SM3

BM2

. ~
Ion fast extraction

SMS

Ion injection
electron extraction

Fig. 2. An arrangement of straight section B.

SM2 located at the straight section of BSR. The ionbeam is eventually kicked and placed in the reference
orbit by the kicker magnets. These kicker magnets
are used for the ion-beam fast extraction. Therefore,
kicker magnets must be risen and fallen less than 50
ns. 1 }
On slow extraction process, at first, the sextupole
magnets (SE) as a resonance exciter are excited. Secondly, the horizontal tune is moved from the operating value 6.691 to a value near the third order resonance (20/3) by changing the excitation currents ofquadrupole magnets. Beams which have deviated inside by the distance more than 25 mm from the central

orbit at the entrance of the ES are deflected inward aslarge as 3 mrad by the static high voltage of ES.
The betatron oscillation can be expressed by the following relation:(X) (-VI1-+ac:
Y

=

a 2c

~c)
I + ac:

(Xo)

Yo'

where

231

(3
y = VI + 02x,~7r) ,( G cos ( W - X -.

~ G cos ( W + X - ~7r))

Let Wj be the deflection due to the i-th sextupole magnet (Sej). Then,
B~'

where

Wj = gjx?, gj = 2Bp'

tan X =

where Xj is the displacement of the orbit from the equilibrium orbit at SE j and gj is the strength of the SEj.
Here we assume that the transfer matrix r j from electric septum to sextupole magnet is

VI + 0 2 + 0,

and

G=

c:(1 + 0 2 ) ~4{3gV A2 + B2

The area of the triangular separatrix in the (x,x') planeis given by
In the third resonance, particles pass each sextupole
magnets three times per period. Therefore, taking asummation of the contributions from each magnet over
one period, we have a Hamiltonian:S = 3)31'
4 SIn 2X I~G2
(3.

Here, S is assumed to be 1011" mm·mrad. The momentum spread is dp/p = ±0.1%. Hence, a beam
is extracted from that with dp/p = 0.1% to thatwith dp/p = -0.1% by turns. When a beam with
dp/p = 0 has horizontal tune value Qo, a beam with
dp/p = 0.1% has Qo + ~dp/p. If the value of c: is same,the extracted direction of the beam is same. Resultof the simulation c: is shown in Fig. 3. As shown in
Fig. 3, at the entrance of ES the outgoing trajectories are overlapped each other. 3 ) Thus, we have foundthat the ion-beam slow extraction can successfully be
carried out by using the third order resonance.

where E means the summation over one revolution.
Defining the angle of rotation of the coordinates W asgiven by tan 3w = -EgjBj/EgjA j, the coordinates aretransformed as

(X')
Y'

= ( cos WW) (X).
Ysin-sin W cosw

Then, we can rewrite the above Hamiltonian as
H = _~(X'2 + y'2) + (3gV A2 + B2 (X,3 _ 3X'Y,2),
2
3va+ 0 2

PHASE SPACE.

from which we can obtain the following three unstable
fixed points:

]

§

-><

10

0
-10

-20

.

..

n··-J~_._ .
"septum.
-40 -20.
0.
20x =- 5.0mm
x' = O.Omrad
SE1: k2 = 20.2 m ·3
SE2: k2 = 2.0 m ·3

40

X [mm]

Fig. 3. The separatrices and outgoing trajectories ofbeams with dp/p = -0.1, 0, 0.1%, respectively, at ES.

Transforming back to the (x,x') plane, we obtain thefollowing unstable fixed point: 2)
G cos(w - X), -(~(3
G cos(w + X)

( G cos ( W - X +~7r ) ,

-

232

~
2))
{3
G cos (W + X + 3"
7r)

References
1) T. Ohkawa et al.: Proc. 17th PAC (Vancouver, 1997).
2) Y. Kobayashi: Nucl. Instrum. Methods 83, 77 (1970).
3) T. Ohkawa et al.: Proc. 11th SAST, Harima Science
Garden City, Japan, 1997, p. 285 (1997).

RIKEN Accel. Prog. Rep. 31 (1998)

Simulation Study of Ion Beam Bunching with Electron Cooler
at Double Storage Ring of MUSES
M. Takanaka and T. Katayama
Collision experiments with ion-ion beams and ionelectron beams are planned in the double storage rings(DSR) of RI-beam factory project. Bunched ion beams
will be formed to obtain a high luminosity by controlling the momentum spread with an RF system, while
the beams are cooled by an electron cooler. The longitudinal and transverse space-charge forces are dominant over the inductive or resistive force induced
through the coupling impedances between beams andvacuum chamber in the region of DSR energy below
1.5 GeV /u. Both space-charge forces become large
with the bunch shortening.
The bunch shortening is known to be disturbed by
the longitudinal space-charge force below the transition energy. Beams are trapped into more resonances,when incoherent or coherent betatron-tune shift is
made larger by the monopole or dipole component of
the transverse space-charge force, respectively. Thesephenomena are not good for obtaining the high luminosity. Simulations of the beam bunching can predictwhether there is any obstacle to obtaining a high luminosity.
In the simulation where coupled-bunch phenomena
are not dealt, the following forces have been taken into
account as forces acting on ions:• the RF force,• the longitudinal and the transverse electron cooling forces, 1)• the linear and the nonlinear forces coming fromthe ring lattice,• the longitudinal space-charge force,• the monopole and dipole components of the transverse space-charge force.
The longitudinal space-charge force has been estimated by using a following equation for the spacecharge impedance of a round beam having a Gaussianradial charge distribution:=' 9 (T) Z
2{3
[ZlIj
n
sp

9 (T) ~ -

Z

"(

1

2

00

2

x=~

0,

-x

(b)- ,XT_e- dx + 2 log

9 (0) "" 0.577 + 2 log(~o-) ,

where CT is the standard deviation of the distribution,
the radial position from the center of the beam, Zo
the free space impedance, and b the inner radius of
the vacuum chamber assumed to be cylindrical andperfectly conducting. As actual beams are not round,the following expression has been used for the CT:T

CT =J0-2h +20-v2'

where CTh and CT v stand for the horizontal and the vertical rms beam sizes, respectively. The dipole component of the transverse space-charge force has been
estimated by using the following equation for a ringtype of space-charge impedance:. ZoR

Z..L = Z(32"(2(1

9CThCT

v

-

1)

b2

'

where R is the mean radius of the DSR.
If a beam is electron-cooled under a constant RF
voltage, the momentum spread of the beam decreases
until the longitudinal microwave instability occurs.
Therefore, for the sake to avoid such an instability the
momentum-spread control is necessary in a way that
increase of RF voltage can cancel the decrement of the
momentum spread due to the electron cooling.
As an example, simulated results are shown below
for an u~~t -ion beam of 150 MeV /u. The parameters of the coasting beam to be bunched, of the ring,and of the electron cooler as input data for the simulation have been listed in a previous report. 2 ) The initialcharge distribution of the coasting beam was assumed
to be flat along the RF phase axis, while it was assumed to be Gaussian along the momentum axis. The
transverse phase-space distribution was assumed to be
Gaussian, too. The average beam current used in thesimulation was 3.4 mAo The peak current reaches 59
rnA, when the beam with 6-rms momentum spread of
10- 3 and rms transverse emittance of 10- 6 7r m·rad isbunched to the 6-rms length of 0.4 m. The peak current is the threshold one estimated with Keil-Schnell
criterion for the longitudinal microwave instability. 3)
A sextupole element located at the cooling section
has been introduced in the simulation as a sourceof nonlinear force. The field strength expressed byB"l{3ec/ Bp was assumed to be 0.3 m- 1 , where {3ec isthe {3 function at the section. The strength is equal toabout 1/10-1/30 of the effective strength of the sextupole magnets used for slow beam extractions. The
sextupole field induces the following major resonancesnear and below the working point:
3Vh = 22,+ 2vv = 4, andVh = 7.
-Vh

The stop bandwidths of the above three resonances
are estimated at about 0.0001, 0.0002, and 0.0004
for a beam of the rms emittance of 10- 6 7r m·rad,233

respectively.4) The simulation has shown that there
is no remarkable enhancement in the transverse emittance due to the nonlinearity even when the incoherent
betatron-tune spread is over 0.5 owing to the improvement of the bunch shortening, as shown in Fig. 1. 2 )This means that the incoherent tune spread does notcause any problem in the beam bunching when theworking point under no space-charge effect is chosen
to be far from the minor-resonance lines as well as the
major-resonance lines.

6 , ---.,-----.,-----,.----,.----,.----.,...----, 1.1 10.3

Time (ms)

6 , -----r---,----,----,------,------,-------, 1.1 10-3

2~,-------~------.------,-------,-------,

Synchrotron tunec;e 1500
'"
U
<U

.~

Fractional horizontal
betatron tune

Fractional verticalbetatron tune

>§

8- ~E

1~

4

Q.

i ~3

'0

~ ~

0
Z

"' ....................................................... ..

~ ~

500

~

*4
OV
0

>-- ..\,........... "

g2
'" l

a:l

0.2

0.4

Tune

0.6

0 .8
10

Fig. 1. Tune distribution for 5000 particles when the beam
bunches in the 6-rms bunch length of 1 m. The distributions of the betatron tune are magnified vertically byfour times.

The simulation has shown an effect of the dipole
component of the transverse space-charge force on thebunch shortening, as shown in Fig. 2. The beamreaches a quasi-equilibrium state after 40 ms of bunching, when the dipole component is neglected. The final
6-rms bunch length is 1 m. When the dipole component is taken into account in the horizontal direction,
however, the bunch length becomes 0.5 m only after 30
ms of bunching. The RF voltage of 300 k V is required
for the short bunch. The rms transverse emittancedoes not decrease largely from 10-6 7r m·rad.
The bunched beam has a shape as shown in Fig. 3 at
35 ms of bunching. The shape is approximately represented by a summation of a Gaussian and a parabolic
curve. The parabolic curve corresponds to the distribution of the cooled ions that hardly do synchrotron
oscillation around the bunch center.
The instantaneous beam current of 60 rnA, which
has been simulated here, reaches the threshold currentof the longitudinal microwave instability as mentioned
above. Further simulations in which the resistivewall impedance and other broad-band impedances aretaken into account will predict the effect of the singlebunch instability on the bunched and space-charge

234

15

20

25

Time (ms)Fig. 2. Transition of the beam bunching. Upper Figure:the dipole component is not taken into account. Lower
Figure: the dipole component is taken into account in
the horizontal direction.

g<'
c:

~

u

70

60
50
40

g 30
0

.0
<J)

'"0

20

0

J

10
0
-1.5

-1

--=

-0.5
0
0.5
Longitudinal position (m)1.5

Fig. 3. Bunch shape with a summation of a Gaussian anda parabolic curve at 35 ms of bunching when the dipole
component is taken into account.

dominated beams.
References
1) I. N. Meshkov: Phys. Part. Nucl. 25, 631 (1994).
2) M. Takanaka and T. Katayama: Proc. PAC '97 (1998),
to be published.
3) A. Hofmann: CERN 77-13, 139 (1977).
4) L. R. Evans: CERN 84-15 , 319 (1984).

RIKEN Accel. Prog. Rep. 31 (1998)

Diffusion Beam-Beam Instability in the Presenceof Beam Cooling
Y. Batygin and T. Katayama
One of the serious reasons for limited performanceof a circular collider is the instability due to beambeam interaction. Let us consider head-on collisionsof strong electron beam against counteracted beam ofheavy ion particles with the charge to mass ratio Z/ A.
Luminosity of an electron-ion collider is given by£NiNe
L = -7r(J4
2 Nbunch,(1)

where f is the particle revolution frequency in a ring, Ni
and N e the numbers of ions and electrons per bunch,
respectively, Nbunch the number of bunches per beam,and (J is the rms (root-mean-square) size of electron
beam.
Significance of the beam-beam phenomena is characterized by the value of beam-beam parameter~, which
has a meaning of the linear part of betatron tune shift
due to beam-beam collisions:

E=

fN

rp,8*
e
,
47rri(J2(2)

where rp = e2/47rco mc 2 is the value of classical radius of proton, ,8* the value of a beta-function of thecollider, and ri the ion beam energy. In existing ion
colliders the maximum value of Edoes not exceed themagnitude of ~ = 0.004.1) Limitation in E results inconstraints of the luminosity L, which follows from
Eqs. (1) and (2):small value of ~ was achieved in existing colliders. Two
conditions are essential to initiate a noisy beam-beam
instability: beam-beam kick has to be a nonlinear function of coordinate and the parameter of the kick (rmsbeam size CT) has to be subject to noise. In contrast
to the stochastic particle motion due to overlapping of
nonlinear beam-beam resonance islands, a noise beambeam instability appears in much more simple conditions without excitation of resonances.
Actual value of the noise amplitude in beam size has
not been measured so far. It can be estimated from indirect data. Let us assume, that the maximum numberof turns in existing colliders for one-day operation isn max = 3 . 108 . To prevent doubling of beam emittance, product of diffusion coefficient with the maximum number of turns has to be Dn max < 3. Therefore,
estimated value of diffusion coefficient is D = 10- 8 and
expected value of noise amplitude is:

U=~rg=6.1O-3.

(6)

Electron and stochastic cooling techniques are effective methods to decrease the phase space volume of thebeam. Let us consider a numerical model, combining
betatron particle motion in the presence of beam-beamcollisions with particle cooling:X~+1 )(1 ) (= exp ( _ _
Ndamp

Pn+l

co~e

- sme

Sine)
cose

(3)

. ( P~ :t.P~ ) + M"

Previous study2) indicated an importance of factorof the noise in beam-beam interaction. Noise diffusion
instability can be easily detected via numerical calculations as well as in analytical study under a fluctuationin the opposite beam size (J n = (J 0 (1 ±where uis a noise amplitude and Un a uniform random function
with unit amplitude. Beam emittance growth after nturns under noise regime is given by

exp ( _ _1 ) ( co~e
N damp
- sme

Sine)
cose

. ( Ph ~l,Ph ) + My,

(7)

Y ),

Cn

= V1 + Dn,

(4)

Co

where the diffusion coefficient D is a function of thebeam-beam parameter, noise amplitude, and ratio of
ion beam size, a, to electron beam size 2(J:where Ndamp is the number of turns required to cool
the beam, a betatron angle, and ~p~ a beam-beamkick given bye~ x _ -4 ~Pn -(2:) 4(5)

As it follows from Eq. (5), a noise beam-beam in. stability can exist under any value of the beam-beam
parameter ~. This can be one of the reasons why aX

1 - exp( - r2 /2(J~)(r2 /2(J~),(8)

analogously for ~p~. Matrices M x , and My describe
the ion beam excitation due to scattering: 3)
X

D = 7r2(~u)27r--t x + Alrl,y --t y + A3r3,

Px --t Px + A2 r 2,
Py --t Py + A4 r4,(9)where Ai (i = 1, ... ,4) are parameters defining the final
equilibrium phase space volume of the beam, rj theGaussian random numbers with average value (f) = 0
and rms value (f2) = 1.

235

Figure 1 presents results of the numerical simulationof combined effect of beam-beam interaction and beamcooling. As can be seen, without cooling, the beamemittance monotonously increases due to beam-beamcollisions, while with a cooling, an equilibrium in the
beam size is achieved if cooling rate is equal to theincrement of beam-beam instability.

(a) 4.55
WO

wI:

4
3.5
3
2.5
2
1.5
1
0.5

(n)

En
-=exp
--Eo
ndamp

Eo

l.iI<fY'.J.~.J, ,--

,..

~I"'"

IJfII"""

40

60

80

\

~

~ 1 + Dn.
2

(11)

Therefore, the required cooling rate to prevent beambeam instability, expressed in cooling number of turns,
is:

20

I '~

40

60

80

(12)

Cooling rate is a function of collider regime parameters. Taking the expected number of Ndamp = 2 . 107 ,which corresponds to cooling time of 20 sec in the
Duoble Storage Ring (DSR), and the noise amplitude
u = 6 . 10- 3 , the maximum value of beam-beam tune
shift achieved is

0.2
00

(10)

100 120 140

(b)
0.8 \

Ndamp

2
Ndamp = j)'20n~1---.

On the other hand, beam emittance growth due tonoisy beam-beam instability is described by
En

00

(c)

Let us define the effect of cooling on the beam-beam
instability. Decrease in the beam emittance due tocooling at the initial stage can be described by

100 120 140

1.4~max = -

1{;E

7rU

-N

damp

= 0.017.

(13)

1.2
1
WO

0.8

wI:

0.6

.J . . .

.,.

Luminosity is proportional to the maximum value ofbeam-beam parameter (see Eq. 3). Therefore , utilizing
the beam cooling can result in increasing of luminosity
at least by a factor of 4.

100 120 140

References
1) F. Willeke: Particle Accelerators 59, 27 (1995).
2) Y. Batygin and T. Katayama: Noise instability in nonlinear beam-beam interaction, RIKEN-AF -AC-3, Mar.
(1997), to be published in NIM - A.
3) K. Hirata, H. Moshammer, and F. Ruggiero: Particle
Accelerators 40 , 205 (1993).

T

0.4
0.2
00

20

40

60

80
3

10 n

Fig.
1.
Beam emittance growth under (a) noise
beam-beam instability, (b) beam cooling without
beam-beam collisions, (c) combined effect of beam cooling and beam-beam interaction: equilibrium.

236

RIKEN Accel. Prog. Rep. 31 (1998)

Stationary Particle Distribution of Intense Bunched
Beam in RF Accelerating Field
Y. Batygin
Emittance conservation of a high brightness particle
beam is an issue for existing and future high intensity
accelerator projects. If the beam is matched with external focusing field, its distribution function as well
as beam emittance are conserved. Finding matched
conditions for the beam requires solutions of the selfconsistent problem for beam distribution function inphase space. Self consistent particle distribution creates a potential in which particle motion maintains this
distribution.
The problem of stationary self-consistent particle
distribution in RF field was considered in several books
and papers. In Ref. 1 solution of one-dimensional problem for longitudinal phase space was found. Space
charge density of cylindrical bunch was found to beconstant in every cross section of the bunch, but dependent on longitudinal coordinate. In Ref. 2 spatial particle distribution in 3-dimensional configuration space
was calculated numerically. In this paper an analytical approximate solution for 3-D self-consistent particle equilibrium is found.
Consider an intense bunched beam of particles withcharge q and mass m, propagating in an uniform focusing channel with an applied accelerating RF field.
Single-particle Hamiltonian of particle motion is given
by: 1)
H =p~ + p;2m"

U ext = qVsEw

Ub
+ - 23 + U ext + q-2'

"

"Vs

Vs

_ Z
- qUext V _ q Ub C _ r
Vext - T ' b - Ho ' I" - ~' r] - ~'(1)1 f)Vbf)2Vb

1+ TOrr,
m"
2 2

f)2Vb

~ f)~ + 8~2 + 8r]2,,2( a)2-2= - 8kbb<p "R: exp -(Vext + Vb" ).

(5)Here, b<p == t:l<p/(27r) is a reduced phase bunch length,b == 2IR2/(,8"I ec;) is a dimensionless value of beam
brightness, I is a beam current, and Ie == 47rc omc 3 /q
is a characteristic value of beam current. To solve thenonlinear equation (5), let us follow the method suggested in Ref. 5.
Represent unknown space charge potential of thebeam by Fourier-Bessel series:
Vb = Vo +00

L L Jo(vom~)[Anm cos(kznr])
n=Om=l[10 (~) sin (<ps - ~z).
w zcos<ps-smtps+ Vs(4)where a is a channel radius, Poisson's equation in cylindrical polar coordinates can be expressed as

00

p;

m"

(x;ms) = (Y;ms) = R/2 and (z;ms) are the rms beam
sizes, and R is the beam radius. Equation (3) expresses
the equipartitioning condition3 ,4) of stationary distribution function.
To find a self-consistent particle distribution, one
has to solve a nonlinear Poisson's equation for unknown space charge potential of the beam. Introducing
dimensionless variables:

(6)

(2)

where U ext is a potential of external field, Ub is a potential of space charge field of the beam, " is a particle
energy, E is an amplitude of accelerating field, v s is avelocity of synchronous particle, tps is a synchronous
phase, w is an RF frequency, Or is a transverse frequency of particle oscillation, r is a particle radius, andZ is a longitudinal deviation from synchronous particle. General approach to find a self-consistent beam
distribution function is to represent it as a functionof Hamiltonian f = f(H). Convenient way is to use
an exponential function f = fo exp( -H/Ho). Unknown
constant Ho can be expressed as a function of beam
parameters:
mc 2 _
c t2_ = _mc 2 _
ct2_ = _mc 2 _
c 2l _ (3)16. H = _o,,(x;ms),,(y;ms)(Z;ms)',,3

where Ct and Cl are the rms (root-mean-square) transverse and longitudinal beam emittances, respectively,

where J o(() is a Bessel function, Vom is a m-th root of
the equation J o(() = 0, and kz == wa/vs is a wave number. Expansion (6) obeys Dirichlet boundary condition
Vb (a) = V0 at the surface of the channel. Constant V 0
is defined in such a way that the total potential of thestructure vanishes at the bunch center:To find an approximate solution of Poisson's
equation, let us take only the first term in thenear-center expansion of exponential function as
exp(-Vext - V b,,-2) ~ 1- V ext - Vb,,-2. Poisson's
equation then becomes:

f f [1 + v~m +(kzn)2,,-2 (b<p) (~)2]
8kb
aJo(vom~)[Anm cos(kznr]) + Bnm sin(kznr])]

n=O m=l= (1- Vex d,,2 - Yo'(7)

Space charge dominated beam transport is achieved, if
b »1. It gives a possibility to simplify the Poisson's237

equation (7). Expression in square brackets in Eq. (7)can be taken as a constant close to unity:

With this approximation, self-consistent space charge
dominated beam potential is:

,2

(12)
(9)

Vb = - 1 + 8 V ext .

Second approximation to the self-consistent potential is given by holding one more term in the expansionof exponential function as exp( - V ext - V b,-2) ~ 1- V ext - Vb,-2 + 0.5(Vext + Vb,-2)2, so that we have
Vb = ,2 [1 + 8 - V ext

Substitution of Eq. (10) into Eq. (12) gives the stationary particle density distribution inside the bunch:

per, z) = Po { 1 - V(l +82- )(1 + 8 - V ext )2 - Vext(Vext - 2)].

(10)With increasing of beam brightness (8 --+ 0), solutionof Eq. (10) becomes close to that of Eq. (9).
Taking the first approximation (9), the Hamiltonian
corresponding to the self-consistent bunch distribution
is as follows:

H= P;:~; + 2!~3 + (1 ~ 6) U

ext ·

(11)

Equation (11) indicates that in the presence of intense, bright bunched beam (8 « 1) the stationary238

longitudinal phase space of the beam becomes narrow
in momentum spread, remaining, in the first approximation, the same in coordinate. This is in a qualitative
agreement with the study of Ref. 1.
Self consistent space charge distribution of matchedbeam in the channel is given from Poisson's equationby- 32')'2

Ct2

6)~ _ 26V

ext

2 (~)2+ (~)2}8E.
,8T}(x~m') Cn,) [(1 + 6)2 - 26V l'/2
c

ext

(13)
References
1) 1. M. Kapchinsky: Theory of Resonance Linear Accelerators (Harwood, 1985).
2) M. Reiser: Theory and Design of Charged Particle
Beams (Wiley, New York, 1994).
3) R. Jameson: IEEE Trans. Nucl. Sci. NS-28, 2408 (1981).
4) I. Hofmann: IEEE Trans. Nucl. Sci. NS-28, 2399 (1981).
5) Y. Batygin: to be published in Phys. Rev . E.

RIKEN Accel. Prog. Rep. 31 (1998)

High Brightness Beam Transport in a Quadrupole Focusing
Channel with Octupole Field Component
Y. Batygin
Prevention of emittance growth and halo formation
in a high-intensity beams are a key problem for the
next generation of particle accelerators. Importanceof the problem is connected with the efforts of development of the particle accelerators for heavy ion fusion, spallation neutron sources, and radioactive wastetransmutation. Beam with a nonuniform profile ismismatched within a linear focusing channel. It results in a beam emittance growth and halo formation.
Matching of a realistic nonuniform beam with a focusing channel can be obtained, if the focusing field
is not a linear function of radius any more. 1 ) Ideal
way to create a required nonlinear potential distribution is a plasma lens with specific distribution of opposite charged particles. Another possibility is connectedwith utilization of an alternating-gradient focusing
channel with higher order multipole components.2) In
this paper the effect of octupole field component on
the beam matching in a quadrupole focusing channel
is examined.
Consider an uniform four-vanes quadrupole focusing
structure with octupole field component. Electrostatic
potential of such structure is given byG2 2 cos 2cp + 4
G 4r4 cos 4cp ) smwot,.
(1)
U(r, cp , t) = ( Trwhere G 2 is a quadrupole field gradient, G 4 is an octupole field gradient, and Wo is an operating frequency.
Oscillating field (1) creates an effective scalar potential

Uext (r, cp) =qE2(r , cp)
24mwo
2mc- -2.
J12 _r2 + 1]r4 COS 2cp + _r61]2
q ;\2 2
2
'

[1

1

(2)

where f..to == qG 2;\2/ (V87rmc 2) is a smoothed transverse
oscillation frequency, ;\ = 27rc/wo is a wavelength, and
1] = G 4/G 2 is a ratio of the two field components.
Fig. 1 illustrates equipotential lines of the effective potential (2) . As seen, for a small radius (r) the equipotential lines are close to circles because the quadraticterm rvr2 is dominant in Eq. (2). With a larger r , on
the other hand , they are close to a distorted ellipse.
In Ref. 3 it was found that the self-consistent stationary particle distribution of a matched high-brightness
beam has such a shape that the space charge beam potential Ub is opposite to an arbitrary external focusing
potential Uext:
2 kb
Ub = -, 1 + kb Uext ,

(3)

abed
1.5 1-+----+-+----+1---141--1-+-+-1
11-+--4-+-~~+-+--~

E 0.5
S.

0 1-+4~f--+++-+--+++-I--H--l>. -0.5 I-+-~~~-+-~~of--~-11-+--4-+--+--+-+--~-1.5 1-+----+-+---+--+----t-+-1-1.5 -1 -0.5 0 0.5 1 1.5

x (em)
Fig. 1. Lines of equal values of the potential function
1 2

4

TJ2 6

C ="2f + TJf cos 2<p + 2f fOf TJ = -0.148: (a) C =0.05, (b) C = 0.2, (c) C = 0.35, and (d) C = 0.49.

where b == 2IR2/(,L3,Iec2) is a dimensionless value ofbeam brightness, I is a beam current, Ie == 47rc omc 3 / q
is a characteristic value of beam current, ,L3 and, areparticle velocity and energy, respectively, R is a beam
radius, c is a normalized beam emittance, and k is abeam profile parameter (k = 1 for uniform beam andk = 2 for Gaussian beam). Space charge density ofthe matched high-brightness beam is determined by
Poisson's equation:

Beam with distribution of (4) is maintained in thechannel with effective potential (2). Due to the termcos 2cp, space charge density of (4) is a decreasing function with x-coordinate, but increasing function withy-coordinate, being r2 = x 2 + y2 (see Fig. 2a).
Realistic beam distribution has monotonically decreasing density function with radius. Good approximation to realistic beams is a distribution of the form:(5)
which is close to the truncated Gaussian distribution(see Fig. 2b). Therefore, realistic beam with distribution of (5) is expected to be matched in x-coordinate,
but mismatched in y-coordinate.
In Fig. 3 some results of particle-in-cell simulations
for the beam with distribution (5) in a quadrupolechannel with octupole component are presented. Initial beam distribution given by Eq. (5) was truncatedalong equipotential lines to make beam close to thematched beam given by Eq. (4). As seen, after 100 em
239

b

a

2~. !
! G~
2

U

N

N

z=o

4()()

.

... -I)~

1000

350
300
250
100
150
100
50

l

./

./.J

IW

·2

0.4
0•
.
•

O~

!

0

~

.0.2

-0.4

-0.6

..0,6

·2..5·1·1.$· I-OJOO.$ J J.j 21.$

·1,J·2· J.j· /'(HOOJ I J.j 2 2.J• (em)

z(em)

4()()

2
/.J

z=30cm

ti G~
_

G

0.'

~ 02

G
-1)2

./
·U

-I).'

-2

-I).•

·2~

·1.$·2·1.$·/-0.$0 OJ IIJ 2 2.5• (em)

1.5

1.5

~.

0.'

~ 02

i

... -I)~-l.'·l-J.5 -/.().JOO.' J 1.5 2 2.5
y(em)

1
xlO ·

dO.J

200

0

.0.1
.{}.4

...
".
•
...
".
-l.J

6()Q

0.4
G. • •
G2

!i:

-

G

-1).2
-I).'

-I) ••-1.J-2-1.J-/-O.JODJ J 1.5 22..5·2..5-2-/.5-I'-OJ00.5 I J.J2 1Jy(em)Jl(cm)

J

xIO ·

x lG

G.'

! .'

2

U

0.5

0.5

!

0

i~

z= lOOcm

-0.5

~

0

i

... -I)~./.J·2·2~·2·J.J·l.(J.JOO.J I

Z(CIIl)-I

J.Jl1.J

0

-1).2

-1).2

-I).'

-I).'

-I).•

-2.5·1·/.5·/-O.$00.$1/.$22,Jz(em)·2,j·2.J,j·I.().jDO.5 J I.J 2 2..5
y(em)

-I
-0.5

0

0.5

1.5

x (em)

Fig. 2_ a: Matched beam with the density profile Pb = po
(1 + 6T]r2 cos 2<p + 9T]2 r 4) in quadrupole-octupole channel with parameter 'TJ = -0.1 and b: beam with theparticle distribution Pb = po [1 -

(-~:)

2f·

of beam transport, which corresponds to one betatron
particle oscillation, emittance of the beam is slightly
distorted at X-Px phase plane, but seriously distorted
at y-Py phase plane. Therefore, utilizing octupole component in a quadrupole channel is not sufficient toprovide beam matching. Better results were observedin computer simulation of the beam in a quadrupole
structure with duo-decapole field component. 3 ) In that

240

0.2

!i:

G

-I).•

•l.J

-0.5

0.'

~ G.2

0

./

;...

;...

E o~

Fig. 3. Dynamics of the 150 keY, 100 rnA and 0.06 7r
em mrad proton beam with distribution of Eq. (5) ina four vane quadrupole structure with the field gradient G 2 = 50 kV /cm 2 and the octupole component
4
G4 = -3.5 kV /cm .

case the effective potential and matched beam profile
are symmetric functions with y as well as x coordinates, and realistic beam is much better matched withquadrupole focusing structure.
References
1) Y. Batygin: Phys. Rev. E 53, 5358 (1996).
2) Y. Batygin: Phys. Rev. E 54, 5673 (1996).
3) Y. Batygin: Proc. 1997 Particle Accelerator Conference,
Vancouver, Canada (to be published).

RIKEN Accel. Prog. Rep. 31 (1998)

Design of 300 Me V Electron Linac at MUSES
M. Wakasugi, Y. Kamino,* and T. Katayama
We have designed an electron linac to be used as an
injector of the booster synchrotron (BSR) at MUSES
project. Electron beam accelerated up to a requiredenergy by the BSR is injected into the double storagerings (DSR), and it is used for electron-RI collision 1)
or for high brilliant X ray production. 2 ) Depending on
the experiment, two kinds of specifications are required
for the electron beam at the linac. When we makeelectron-RI collision experiments, electrons should bein a specified RF bucket in the DSR because of synchronous collision. This means that the BSR has to be
operated with the single-bunch operation mode. So,
the electron beam after the linac has to have a shortpulse length and high peak current. On the other hand,
every RF bucket should be filled with electrons at theDSR, for X ray production, and the BSR be operated
with the multi-bunch operation mode. In this case theelectron beam from the linac has to have a long pulelength. The electron linac, therefore, is required tohave the specifications summarized in Table 1.
From the requirement of both experiments, the minimum electron beam energy is decided to be 300 MeV.
The linac consists of three parts: an electron gun, an
injection part, and a regular part. They are shown in
Fig. 1.
The electron gun includes a cathode-grid assembly

Table 1. Specifications of electron beam after the linac.
RF frequency
EnergyRepetition rate
Energy spread
Normalized emittance
Pulse width
Peak current

\~~~

(%)
(7r mm mrad)(nsec)

(A)

,
,

'.;,.

Q'
(?

SOMW
Klystron

SOMW
Klystron

\

\

~L,.

\

~

ca.t.y

\

~

';...

1
1

SOMW

~

\

Short pulse mode

Klystron

\

~\~}\
~~

Long pulse mode
2856
>300
50
±0.25
100
5000
0.1

(MHz)
(MeV)
(Hz)

,j)

~
<.'>L,.

\

~

ca.
~;...

\ ca.

\

~

ca.

~

\

\
~

ca."(-

~

~

~

~

~

f,.

'%z.

'%z.

\ ca.

"(~

~

~
'tL,.

Fig. 1. A conceptual 300 Me V electron linac system at MUSES.

which has a cathode area of 0.5 cm2 and allows the
maximum current of 1.6 A. These parameters havebeen decided from the beam quality point of view. The
electron beam is extracted with an acceleration voltageof 100 kV from the gun. Pulsing for both modes are
made by pulsing grid voltage. The simulated beam
trajectory in the gun, obtained using computer code
EGUN2, is shown in Fig. 2.
The injection part consists of a pre-buncher 1, prebuncher 2, and buncher. The pre-buncher 1 is a
Mitsubishi Heavy Industries, Ltd.

Cathode/Grid
Assembly

Fig. 2. Ray trace of the electron beam at electron gun.

241

standing-wave type single cavity, and its gap voltage
is 10 kV. The required RF power is estimated to be 1
kW. The pre-buncher 2 is a traveling-wave type andconsisting of the four cavities made from disks andspacers. The phase velocity (vph/c) is 0.77 which ismatched with the beam velocity. Acceleration gain is
2.0 MeV 1m and RF power of 170 kW is required. The
buncher is a constant gradient (CG) tube including 30
cavities. Acceleration gain is 11 MeV 1m and input
RF power is 15 MW. All bunching devices are in asolenoid coil for focusing in low energy region. Finally,
expected electron beam energy at the end of the injection part is 13 MeV, and the phase spread and theenergy spread are expected to be within 4 deg and 200
keV, respectively, as shown in Fig. 3.

Fig. 3. Phase and energy distributions at exit of injection
part for short pulse mode.
The regular part consists of seven CG tubes. We
provide three groups of CG tubes: three tubes forgroup A, two tubes for group B, and two tubes forgroup C. The CG tubes in groups A, B, and C haveattenuation constants of 0.5, 0.6, and 0.7 [Neper], respectively, and different aperture sizes to avoid the cumulative beam break up (C- BBU). One CG tube has
80 cavities, with total length of 3 m and acceleration
gain of about 16 MeV 1m taking a beam loading effectinto account. Five triplet-quadrupole magnets work
as a focusing element during the beam transport, andthe beam size at the exit of the linac is expected to beabout 1 mm in diameter.
All cavities and tubes are driven by four klystrons
having each peak power of more than 50 MW and fre-242

quency of 2856 MHz as shown in Fig. 1. RF powerof the first klystron is divided into bunching devices
and the AO regular tube. Each of the other klystrons
supplies two CG tubes the RF power.
We have estimated energy resolution of the beam bytaking the following points into account: (1) fluctuation of RF voltage due to instability of klystron, (2)fluctuation of phase due to instability of klystron, (3)beam distribution in E-fJ phase space, (4) deviation ofacceleration phase due to error of phasing process, (5)reactive phase distortion, and (6) initial beam loading
effect. For (1) and (2), we have estimated to be lessthan ±0.09%, and phase spread for (3) is less than ±2
deg as shown in Fig. 3. The phase shift for (4) is expected to be less than ±1 deg. We further expectedthat the initial beam loading effect can be suppressedwith the modulation of RF power before beam loading. If we supply the RF voltage as shown in Fig. 4,
every bunches feel the same field in the CG tube. The
field is the same with the equilibrium state after beamloading for the case of normal RF power filling method.
Finally, we were able to estimate the energy resolution
to be about ±0.2% which is better than the requirement.

....

CI), 00% ~Itle<

Full Power

0 \lo ....---------1

i ~i
~

~
S2

50% ~

Beam ON

O%~---~I-------_~I

1 J1Sec

2 J1SecTime

Fig. 4. RF power modulation sequence at beam loading.

References
1) T. Katayama et al.: Proc. 5th Eur. Part. Accel. Conf.
p. 563 (1996).

2) M. Wakasugi et al.: Proc. 5th Eur. Part. Accel. Conf.
p. 611 (1996).

RIKEN Accel. Prog. Rep. 31 (1998)

Design of Apple-II Type Undulator for MUSES
M. Wakasugi and T . Katayama
We have designed an Apple-II type undulator, which
will be installed into the double storage ring (DSR)
in MUSES project. According to requirements fromphysics experiments, we have to continuously change
the X ray energy from 30 to 800 eV and its polarization
as well. That is why we are to chose Apple-II type.
Apple-II type undulator has two pairs of magneticarrays as shown in Fig. 1. X ray energy can be changed
continuously by driving vertically the gap-width asshown by white arrow in Fig. 1. The polarization can
be changed by shifting the phase (D) between pairsof the magnetic arrays shown by black arrows in Fig.
1. In one period , total 16 permanent-magnet chips areused, and the length of one period is 30 mm. The
minimum gap-width has been decided to be 20 mm byconsidering size of the vacuum tube which is put inbetween magnetic arrays. The gap driving range is 6.7
mm with a step of less than 5 /-Lm. The minimum gapdriving step corresponds to the X ray energy-scanningstep of 0.1 eV at X ray energy of 100 eV.

Table 1. Kx and Ky values vs. gap-width and phase-shift.
Gap width (mm)2320Phase (mm)
0
3.75
7.5
11.25
15

26.7

Kx

Ky

Kx

Ky

Kx

Ky

0
0.143
0.261
0.342
0.370

0.712
0.658
0.504
0.272
0

0
0.098
0.179
0.235
0.255

0.521
0.482
0.370
0.199
0

0
0.062
0 .115
0 .151
0.163

0.356
0.328
0.252
0.137
0

0.3 "'-:-~"""'-'-"""'-'-'---'-~'---'-""""""'r-r-'--'--'
0.2
0.1

o

-0.1
-0.2

E:

-0.3 0

20

40

60

80

1

120

0.3

~~~~) '~:B~~ '~:']

'l~~
~

0

20

40

60

80

100

120

i1 [.(:).:.:. :. :.:. :. :. :. :. :.:. :":":":'::":'·:··:·1
o

20

40

60

80

100

120

Length along Z-axis (nun)Fig. 2. Magnetic field strength at the phase shifts of 0mm (a) , 11.25 mm (b), and 15 mm (c). It is assumed
that the magnetic field is 1.3 T at the pole tip.

Fig. 1. Magnetic structure of Apple-II type undulator.

Phase-driving changes mainly the X ray polarization from linear polarization to circular polarization.
It also changes slightly the X ray energy, because thebending factors Kx and Ky in horizontal and verticaldirections, respectively, are change by the phase driving. Therfore , if we want to scan the energy withoutchanging the polarization, we have to drive both thegap and phase simultaneously. Relations between the
gap-width, the phase-shift and K values are summarized in Table 1.
The phase shifts of 0 mm and 15 mm give linearlypolarized X ray in the horizontal and vertical directions, respectively. The shift of about 11.25 mm, whichcorresponds to the 3/8 length of one period, gives thecircularly polarized X ray. For these cases, magnetic
field strengths on beam axis are shown in Fig. 2
We have calculated the photon spectrum with theundulator described above. Parameters of electron
beam used here are shown in our previous paper .1)
Figure 3 shows typical examples for the cases of lin-10'· c__ ============="'"=

10'·

200

400

800

800

Photon Energy (eV)Fig. 3. Calculated X-ray photon flux for the cases of linear
polarization (a) and circular polarization (b).
243

ear polarization and circular polarization. To coverrequired X ray energy range, we have to change not
only the gap-width but also the electron beam-energy.
Electron beam energy will be changed from 0.3 GeV to
1.7 GeV. Intensity of the X ray is expected to be morethan 10 15 photons/s/0.1%b.w. in both polarizations,which exceeds requirement to the good.
We have made mechanical design of the undulator,
and a realistic drawing is shown in Fig. 4. We provide
a 6.7 m space to install the undulator in the DSR. Actually, it is not so easy to make 6-m long undulator
because it is too long to keep high precision for the

gap-width and phase-shift drivings. So, we will separate it into two units. Figure 4 shows one unit of theundulator. Each unit contains: 80 periods of magneticarray, a correction magnet, gate valves, servo motor forboth gap-width and phase-shift drivings, vacuum tube
and some monitors, so on. Two units are connected
in tandem and are put at the undulator section of theDSR. The size of the unit is 3.1 m long, 2.8 m wideand 2.4 m long, and the weight is expected to be 7.5
t per unit. Accuracy of the gap-width driving can beachieved better than 5 /-Lm using linear guides and position sensors. That of phase driving is expected to be

3120
2400

Electron
Beam Linel\.

Vacuum Chamber

Fig. 4. Mechanical construction of one unit of the undulator, designed here.

25/-Lm. Magnetic force which acts on a magnetic arrayis estimated to be 1.07 t in horizontal direction, 0.17 t
in vertical direction, and 0.78 t in direction of beam.
Vacuum tube has three rooms as shown in Fig. 5.
One is for the low emittance electron beam and it isput inbetween magnetic arrays when we use the DSR
as a synchrotron radiation light source. The second
room is for the ion beam or for the large emittanceelectron beam. When this room is used, the gap-widthof the undulator is expanded to 300 mm so that themagnetic field dose not affect the beams. The thirdroom is for NEG pump. When we want to use ion
beams or large emittance electron beams, the chamber
will be moved horizontally without breaking vacuum.

244

Fig. 5. Vacuum tube put inbetween magnetic arrays.

References
1) M. Wakasugi et al.: Proc. Part. Accel. Conf. (1997).

RIKEN Accel. Prog. Rep. 31 (1998)

Safety Design of RIKEN RI Beam FactoryN. Fukunishi, S. Ito, Y. Uwamino, and T. Kurosawa
We estimate here the shielding thickness required for
the RIKEN RI Beam Factory (RIBF). The RIBF plans
to provide high-intensity heavy-ion beams for fundamental research. Hence, we need a precise estimationof shielding thickness to assure radiation safety. We
employ here two different methods in estimating theshielding thickness. For a 400 MeV/nucleon heavy-ion
beam, we use the experimental data of double differential neutron yields with thick targets!) as source termsof shielding calculation. Deep penetration of neutrons
into the absorber is calculated by using the ANISN
code which is widely used for the calculation of neutron transport. The cross section data used here isbased on the HIL086R data sheet. On the other hand,
we do not have experimental data useful for the radiation protection estimation against a 1.5 GeV /nucleon
heavy-ion beam. Hence, we employed the Moyer model
which is widely used for the radiation shielding computation against high-energy proton accelerators. In
our case, fast neutrons mainly contribute to the dose
equivalent, and the neutron production strongly depends on the energy and mass number of accelerated
ions. We assumed here that the neutron production is
proportional to the square of the beam energy below
800 MeV/nucleon, and is proportional to the beam energy above 800 MeV/nucleon. We also assumed thatthe neutron production is proportional to the mass
number of the ion. For the details of calculations, see
Ref. 2.
We summarize in Table 1 the shielding thickness required for a 40Ca beam. The shielding material chosen
here is ordinary concrete. We may have to use othershielding material, for example iron absorber, in casethat the shielding thickness given in Table 1 exceeds
the distance from the source. As shown in Table 1,

Table 1. Shielding thickness required for the RIBF.
Acceler- Energyalor(MeV/u)Beam Loss)

Place

Direction(pps)

Shielding thickness (m) required to satisfy thecondition that the dose equivalent < D(J.1Svlhour) at the distance L (m) from thesource

SRC

400

BSR

400

400

1500

1500

0=6

0=20

L=IO

L=10

L=20

L=20
8.03

extraction forward

9.54

8.84

8.73

6*10 10
6*10 12lateral

4.43

3.79

3.69

3.05

forward

12.22

11.52

11.41

10.71

lateral

6.89

6.24

6.15

5.51

0=6

0=20

0=6

0=20
L=IO

1.62*10"dump

injection

L=5

L=5

blO

forward

10.92

10.22

10.12

9.41

lateral

5.70

5.06

4.96

4.32

1.8* \01 0

ringlateral

3.76

3.10

3.38

2.74

6* 109extraction

forward

9.00

8.30

8.20

7.49

lateral

3.94

3.30

3.20

2.56

1.74* 109

injection

forward

8.28

7.58

7.47

6.77

lateral

3.28

2.64

2.54

1.90

lateral

4.05

3.39

3.67

3.02

extraction forward

8.50

7.76

7.65

6.92

lateral

6.11

5.37

5.26

4.53

forward

3.64

2.91

2.80

2.07

lateral

1.26

0.52

0.41

0 .0

lateral

2.05

1.46

1.70

1.15

8.7* 109
8.7* \09

DSR

0=20

6*IOtO

6*10 12

ACR

0=6

ring

3*106

injection

3*\08

ring

we need shielding thickness more than 10 meters for acouple of high radiation areas in the RI beam factory.
References
1) T. Kurosawa: Master Thesis (Tohoku University, 1997)

and private communication.
2) Details of calculation are in "MUSES Conceptual Design Report", RIKEN-Cyclotron (1997).
3) Present values for the beam loss are suggested by the
RIKEN accelerator group who design these accelerators
for the RIBF project.

245

RIKEN Accel. Prog. Rep. 31 (1998)

Spin Depolarization Due to Beam-Beam Instability
Y. Batygin and T. Katayama
In our previous studyl) we found the following matrix of spin advance in a collider ring with one beam-

(-1)
Sx

n+1

2

2

[Ln C,os (i9+'I')] 2}
2 i=O .

{I - £...

2

L

Sz

.

L (_I)i+D sin (i9+'P)

<P

Sx,o

L (-Ii sin (i9+'P)

Sy,o

i=O

(_I)n+1i=Owhere n is a turn number, W is an initial phase ofbetatron particle oscillations, B is a betatron angle, <p
is a small parameter as
IlrG

2« 27r,
eO'

(1)

Sz,o

[1 - n+l <1>2+ ... ]2(a)

1.3 ,--,--,--r--r--r-,r-,r-,----,----,
1.25 I--t__t__t__I--------;I________;I________;I----il----il----i
1.2 I--t__t__t--t--it--lt--lt--ll----il----i(2)<p = - I

L cos(i9+'I')
i=O

D

2

n.

{L

n

<P

n

(_1)D+I<I>

i=O2

1- <1>_(-IY sin (i9+'I') }
2 i=O

4

i=O
D
(_I)n<l> Lcos(i9+'P)
i=On(L (_I)I+n sin 2(i9+'I') + ... ]4D~ [L (_1)i+1 sin 2(i9+'P) + ... ]Sybeam interaction point and two Siberian Snakes Installed:,jj1.J 5 I - - t - - t - - t - - t - - t - - t - - t - - - - i - - - i-;. 1.1 I - - t - - t - - t - - t - - t - - t - - - - i - - i---i(oJ

1.05 ~•.-".+.. _~ .+-.,.- +-"-+--+:.,--1.:1... --1.. 1--:...,--1.i--:..,."..-!,.-•• ..,-I.

3

I is a beam current, Ie
47rf o m o c /q
(A/Z) ·3.13· 10 7 Amp is a characteristic value of thebeam current, I is a bunch length r is a radius of particle trajectory, G = 1.7928 is the anomalous magnetic
moment of proton, and 0' is an rms (root-mean-square)beam size. From attained matrix, it follows that spin
depolarization is not taking place or suppressed if betatron tune values are chosen far away from low-orderresonances, and that beam-beam collisions are stable.
Actually, suppose that the initial spin has only one
transverse component, i.e., Sx = 0, Sy = 1 and 8 z = 0.
After n turns, the average and rms values of spin components are as follows:!)

Sx = 0,(8

Sz = 0,_2) = [ rp2 _]28(cosB)x(82 ) z-1 (8y = 1 - -- ]2<p[2 cos(e
/2)

8

(8

cp
cos(B /2)

2) = ~ [y256: .', •

' \ " ~#". "••:".......

- .

(b)

0.999995 I--I--t--t--+--+-+-+-+-+-'-I
0.99999 I--I--t--t--+--+-+-+-+--t---i0.999985 • • • • • • • • • •0.99998 I--I--t--t--+--+--+-+-+--t---i0.999975 I - - t - - t - - t - - t - - t - - t - - - - i - - i---i0.99997 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
5
10 n

~
~I\

0.01 .,-.---.---,--,.....:(C,.:-)--.--.--.--.--,
0.009 E--t--t--t--t--t--t--+--+--+----i
0.008 E--t--t--t--t--t--+--+--+--+----i
0.007 E--t--t--t--t--t--+--+--+--+----i

0.006 ~ee~~~~~~~.':!.. 0.005 ~

C\lN
CJ)

cos(B/2)

O. 004 ~t__t__t--t--I________;I________;I----iI----i---1(4)

0.003 ~t__t__t--t--I________;I________;I----iI----i---1
0.002 ~t__t__t--t--I________;I---1I----iI----i---1
O. 001 ~t__t__t--I--------;I________;I---1I----iI----i---1
0 0 0.5 1 1.5 2 25 3 15 4

~5

5

5

e

where rp and are the average values of parameters <p, B
among all particles. In Fig. 1 results of particle motion
and suppressed spin depolarization in the presence ofstable beam-beam interaction are presented.
There are several mechanisms which lead to particle
instability under beam-beam collisions. Excitation of
nonlinear resonances and unstable stochastic particle
motion due to overlapping of resonance islands are thefundamental phenomena in beam-beam interaction. 2 )Another mechanism of unstable particle motion is adiffusion created by random fluctuations in distribution of the opposite beam. In Ref. 3 the noise beambeam instability was studied for the case of random
fluctuations in the opposite beam size
246

".t..

103 n

)2 , (3)~ ]4•0.95 1--t--t--t--t--t--t--'l1--------;1----i1----i
0.9 l.J.u..LLu.w.Lu.w.1.u..U.l..u..u.J..u..u.J..u..u..Lu..u..Lu..uu.....u...Jo 50 100 150 200 250 300 350 400 450 500

10 n

Fig. l. (a) Beam emittance, (b) average value of Sy, (c)(_)1/2rms value of (S~)
as a function of the turn number
for stable beam-beam interaction.

U· Un)

O'n=O'o ( 1±-2-,(5)where u is a noise amplitude and Un is an uniform
random function with unit amplitude. It was shownthat in the presence of noise, beam emittance increases
with the turn number n as

Cn

= Vi +Dn.

(6)

Co

beam parameter E, noise amplitude u, and ratio ofbeam size a with respect to opposite beam size 2(70:Here, diffusion coefficient D is the functions of beam-

(7)
(a)

"

. ~ :.

:~~. Ji;l~l!f'~~$- lJ~~ ~riE~fI#":"

0.95 1'--+-+-+-+-+---+--+--+--+--1
0.9 0

50 100 150200 250 300 350 400 450 500

103 n
(b)

1

t'-...
0.99990.9998>- 0.9997(/) 0.9996'r--...

J'..

"'r--....
1'"

0.99950.9994~........

0.9993 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
5

10 n
(c)

0.04

-

0.035
./'
~
0.03
~,.....
,.p.025
1/.....
'Q 0.02,/......... 0.015
V
0.01 I'
0.005
00 a5 1 [5 2 25 3 ~5 4 ~5 5
5
10 n

:'A

Fig. 2. (a) Beam emittance, (b) average value of Sy, (c)(_)1/2 as a function of the turn number

rms value of (S~)

for unstable beam-beam interaction.

Noise in the beam-beam collision always induces instability if beam-beam kick is a nonlinear function of
the coordinate. Due to diffusion character, noise beambeam instability does not have a threshold characterand can exist at any value of beam-beam tune shift.
Increase of beam emittance is accompanied with increase of beam size.
In Fig. 2 the results of beam dynamics and spin depolarization in the presence of noisy beam-beam instability are presented. Parameters of the process werechosen the same as for the stable beam-beam interaction without noise as presented in Fig. 1. The valueof noise amplitude u = 0.025 was chosen arbitrarily,
to demonstrate the main features of diffusion beambeam instability. As is seen, increase of beam sizes
due to beam-beam collisions results in spin depolarization. It is also expected from analytical formulas(3)-(4), where the average and rms beam parameters
are proportional to the powers of the small parameter <p, which, is proportional to beam size according to
Eq. (2). Therefore, if beam is subjected to beam-beam
instability, it causes spin depolarization.

References
1) Y. Batygin and T. Katayama: Proc. 11th Symp. on
Accelerator Science and Technology, 21-23 Oct. 1997,
SPring-8, Harima Science Garden City, p. 822 (1997).
2) L. R . Evans: CERN 84-15, p. 319 (1984).
3) Y. Batygin and T. Katayama: "Noise instability innonlinear beam-beam interaction", RIKEN-AF-AC-3,
March 1997, NIM-A, Vol. 404, p. 1 (1998)

247

RIKEN Accel. Prog. Rep. 31 (1998)

Study of Spin and Orbital Motion in Siberian Snake Based on
Calculated Three Dimensional Magnetic Field
M. Xiao and T. Katayama

The study on orbital motion and spin precession ofpolarized protons in Siberian Snakes in RHIC is oneof the subjects of particular interest in RHIC Spin
Project. 1 ,2) For a better representation, the simulation
based on three dimensional (3D) magnetic field map(calculated or measured) is of importance. The work
has been initiated by Luccio,3) but two main problemson the optimization of the numerical spin matrix andorbit matrix for Siberian Snakes still remain. The two
problems are: (1) numerical spin matrices should be
unitary, and (2) numerical orbit matrices should be
symplectic, that is to say, the determinant of themshould be exactly unity (1).
Each Siberian Snake consists of four right-handed
helical dipole magnets. The results of magnetic fieldmeasurement for the prototype of a helical magnet
agreed well with the 3D numerical calculation by
TOSCA. 4 ) It was therefore encouraged to work further based on the calculated magnetic field map for amodified magnet configuration, and to look for suitable
methods to solve the problems mentioned above.
Bicubic spline function method was introduced first
to interpolate Bw (x , y, Sk) (w = x, y or s) (k =1,2, ... Lk) and their derivatives in Cartesian coordinates for the calculated magnetic field map given on
the (x,y) plane (s = Sk) ,Bw (x , y, Sk)4=

2: AwijKL(X,y)(x - xdK-1(y - Yj)L-l

K,L=l
Xi :::; X :::; Xi+l, Yj :::; Y :::; Yj+l(i = 1,2, ... , m - 1; j = 1, 2, ... , n - 1)

where the coefficients AWij K L (x , y) can be determinedby one-dimensional cubic spline function, and the corresponding boundary conditions were calculated by
two-dimensional 3-points Lagrangian function. Theinterpolation in s-direction was done again by onedimensional spline function,4

Bw(x, y, S) =2: AWkN(S)(S - Sk)N-l22

where u = x' = dx
V = Y' = 1:11.. w = e· v'u +v +1 and
ds'
ds'
molV
'
V is the velocity of a charged particle. B x , By and B s
are the components of magnetic field in x, y and S directions respectively. The equations of spin precessionarePx = fl . [-uB s + (1 + v 2 )Bx - uvBy] + U · f2
P y = fl . [-vBs + (1 + u 2 )Bx - uvBy] + V· f2
P s = fl . [-uB x - vBy + (u 2 + v 2 )Bsl + f2
whereh
fl = Bp . (1 + G1'),h
f2 = Bp . (1 + G)(uBx + vBy + B s ),h=1

vu + v + 1 , Bp = mo')'V, G = 1.7928456.
22

Fourth-order Runge-Kutta method in Cartesian coordinates was used to integrate the above equations inthe simulation. The axis of spin precession was calculated from the results of the integration of two groupsof spin precession. The related program SSTRAN was
written in FORTRAN based on the calculation methods discussed above.
Three components of the magnetic field distribution
on the axis (x = 0, y = 0) for full Snakes are shown in
Fig. 1. Based on the field strength of the first helicalmagnet, the field strength of the second helical magnet was optimized so as to obtain the orbital angles- - Bx----- -. By......... .. Bs

N=lSk:::; S:::; Sk+l , (k = 1,2, ... ,Lk -1).

The equations of orbital motion in natural coordinates are
du

ds =

dv

-

ds

248

=

W·

[
2
uv Bx - (1 + u ) By + vB s]
2w . [(1 + v )Bx - uvB y - vBsJ

Fig. 1. Magnetic field distributions of the full Siberian
Snakes on axis (x = 0, y = 0).

Y:

X~,
at the exit of the Snakes as small as possible
and Sye as closed to -1 as possible for the ray withinitial conditions of (xo, x~, Yo, y~)=(o., 0., 0., 0.) and(Sxo, SyO, Sso)= (0, 1, 0). The amplitude of the firstmagnetic field strength is 1.33626T, the finally optimized amplitude of the second magnetic field strengthis 4.13649T, and the final results of orbital motion andspin precession are as follows:(Xe, x~, Ye, Y:) = (0.24,0.01111, -0.46 , -0.08429)(Sxe, Sye, Sse) = (0.015536 - 0.999734 - 0.017042)
where the units are mm for Xe, Ye, and mrad for x~, x~.
The spin axis obtained is 51.4737° (plane angle with saxis) and -0.0441° (space angle with y-s plane). The
trajectory and spin precession in full Snakes are shownin Fig. 2(a) and (b).

0.04

(a)

0.03

--~m)

-- - ---. y(m)Ms =0.22420.0155[ 0.9744-0.0131-0.9997
0.01900.9745]-0.0170 ,-0.2239

The determinant of Ms is 1+ 1.4777 x 10- 7 . The dependence of the matrix elements on the particle position
and angle was also investigated. The calculation was
repeated for different values of (xo, x~, Yo, y~). The spin
precession of some of the rays with large r (r > 3.0cm)
rotated unregularly, but most of them turned out to bevery close to each other, and the determinant of theirmatrices had the same order of deviation (10- 7 ) fromunity.
To calculate the orbit matrix M T , a certain number of rays, whose initial conditions were generated at
random with Gaussian distribution in emittance, weretraced. By solving a system of algebraic equations between the final and initial coordinates of the same ray,
the Oth order 4 x 4 matrix was obtained. The following
numerical orbit matrix was calculated from the resultsof 16 rays traced,

0.02
0.01

"

0

"

-0.01

=

M
T

-0.02

0.9939-0.00430.0006[0.000610.82810.96570.1631
0.0626-0.01700.00600.9844-0.0049-0.0336]-0.0074
10.6717'0.9485

-0.03
-0.04

-6

-4

-2

0

2

4

6

2

4

6

I(m)

0.8

(b)

0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8

-1

-6

-4

-2

0
I(m)

Fig.
2.
Orbital motion and the spin precessionof the ray with (xo, x~, Yo, Y~) = (0.,0.,0.,0.), and(Sxo, Syo, S80) = (0,1,0): (a) orbital motion, and (b)spin precession.

With the same initial orbit condition of(xo, x~, Yo, y~) = (0.,0., 0., 0.), three representative
rays with initial spins (Sxo, Syo, Sso) = (1,0,0), (0, 1,0)and (0,0,1) were traced respectively, and then the spin
matrix was obtained directly by the final precessed
spin. That is

The determinant of MT is 1 - 4.9183 X 10- 3 .
To check the Maxwellian properties for a given magnetic field map, first derivatives were directly calculated by the coefficients of spline function AwijKL.
The results showed that \7 . B = 0 was well satisfied(10- 6 ) in the region around the axis, and the errorof \7 x B = 0 was mainly originated from (\7 x B)x,
which may be due to the small value of Bs and its
rapid change with y.
Further work will be done for adjusting the magnetic
field map to satisfy Maxwell equations, and a sympletic
integration method will be taken to integrate the equations of orbital motion and of spin precession.
References
1) K. Brown (BNL) et al.: Spin Note AGS/RHIC/SN
No. 001, January 19, 1996.
2) T. Katayama: Spin Dynamics in Synchrotron and Storage Ring, November, 1995.
3) A. U. Luccio: Spin Note AGS/RHIC/SN No. 041,
November 5, 1996.
4) M. Okamura: Spin Note AGS/RHIC/SN No. 060,
August 20, 1997.

249

RIKEN Accel. Prog. Rep. 31 (1998)

Calculation and Measurement of Magnetic Field in Half-Length
Helical Snake Magnet for RHIC
M. Okamura, T. Tominaka, T. Kawaguchi, and T. Katayama
We have studied on acceleration of polarized proton beams in RHIC as a part of the RHIC-Spinproject. Development of the superconducting helical
dipole magnets l ) which are to be used as the Siberian
Snakes is one of the key to the success of this project.
In order to confirm the performance of the magnet, a
half-length model magnet was fabricated by the end of
1996. Three dimensional field analysis has been performed for it using the code TOSCA.2)
The coils of the model magnet are divided into sixteen current carrying blocks. The separation between
the coils and the yoke is only 5.5 mm, and the yokeenhances the field strength about 50%. The current
blocks were designed to be used with two sizes of currents in the ratio of 9 to 11. In order to increase thequench limit, the coils in the stronger field area have alower current. In the latest design of the helical magnet, an uniform current over the cross-section will be
used in stead of the 9 to 11 ratio, to simplify the operation.
The measurements were performed on the model
magnet in February and June of 1997 in a verticaldewer at BNL. The operating current in the "lowcurrent" blocks is expected to be 280 A for 4.0 T. The
model magnet quenched at 139% of the operating current, and the field strength at the center of the magnet
reached 5.0 T. Using TOSCA, field strengths of peaks,
which are found at the inner edge of the coils nearest
to the poles in the body, were estimated. According
to 3D analysis, the coil is expected to quench at 395 A
in the "low-current" blocks corresponding to a dipole
field strength of 5.3 T near the beam axis. The experimental result almost reached the calculated quench
current. The comparison is summarized in Table 1.
Table 1. Quench performance.
Max. current at lower curre nt blocks (A)Max. current at higher current blocks (A)Max. field at the center of the model (T)Experiment Calculation
388
395

474
5.0

483
5.3

To measure the field distribution in the model magnet, Hall probes connected to a cylinder were used.
Rotating coils are usually used to measure magnetic
fields for synchrotron magnets. However, this method
only measures the average field over the length of thecoil. On the other hand, Hall probes have a small sensing area, a few mm 2, and can measure local magnetic
fields. The cylinder was passed through to a long aluminum shaft and rotated by a stepping motor. The
field was sampled at 64 points per revolution. Thiscylinder was also moved axially by another stepping
motor to measure the field distribution along the beamaxis. The reference radius of the multipole components
was 31 mm in analysis. The model magnet was excitedby an uniform current. In the case of dipole component, agreement in both the field strength and phase250

angle is very good. In the case of sextupole component, as shown in Fig. 1, agreement in the end regions,where relatively strong multipole fields are distributed,
is excellent. However, some discrepancies are observedin the body section. It is a possibility that some spurious multipole components were observed due to theplanar Hall effect.

~

2~

8
~

~

I

-

200

r"

..

TOSC\

x

Me:1.wr\.'CI

I
.. -

."

~

'"

I~

I··:,...:><;···· ·:·x... :....>.: .... :.)(.. ~ .... :.....".)(... :..~x;i .. I..:.

100

~

... _

····F··:·'······;·····,·····,······; ····;·· ···,· ····;····,·····;····.· :···;· ·u
~:
~

~

4

~

0

ro

_

~

W

Axial Distance. Z (em)Fig.
1.
Amplitude of the sextupole component(105A/cable for all current-carrying blocks).

To specify the field quality at the center of the model
magnet, we used a tangential rotating coil which has
been used for other RHIC magnets. The length andopening angle of this rotating coil are 230 mm and 15
degrees respectively. In the case of the helical dipole
magnets, there is some reduction in signal due to a rotation of the field over the length of the measuring coil.
For example, the sensitivity of the rotating coil for the
decapole component decreases by 67% of the sensitivity for a normal straight magnet. The measured harmonics were corrected for this reduction in sensitivity.
The results measured by using this rotating coil are
shown by a dotted line in Fig. 1. The calculated ratioof the sextupole components to the dipole component
are smaller than the measured value by about 1 x 10- 3 .
The current dependence of the sextupole component(due to the saturation if iron material) agrees withthe 3D calculation. In this measurement, again, an
uniform operating current was applied for all current
blocks, and the multipole components are larger thanthe design values which assume the use of two currents.
The fabricated model magnet showed a good performance. The measured results of the model agree quite
well with the 3D calculations. Thus, we can rely on
the field calculations and have validated our mechanical design and fabrication method.
References
1) Vector Fields Limited, Oxford, UK.
2) M. Okamura et al.: Proc. Particle Accel. Conf. (1997).

RIKEN Accel. Prog. Rep. 31 (1998)

Optimization of Full-Length Helical Snake Magnet for RHIC
M. Okamura, T. Tominaka, and T. Katayama
A half-length model of the helical magnet for RHI C
has been built and tested successfully. Now we are finalizing a design for the full-length helical dipole magnet.
From the cryogenic point of view, it is necessary tominimize the heat leak from the independently powered helical dipole magnets for RHIC. Therefore, athin round cable of 1 mm diameter comprised of seven
wires will be used instead of the Rutherford-type cable used in the regular arc magnets. The Kaptonwrapped cables are wound in the precisely machined
helical slots on an aluminum cylinder. Thin fiberglass
sheets containing b-stage epoxy are inserted between
layers. Finally, the wound cables are locked in the slots
by heating, while applying radial pressure. All techniques mentioned above were applied in the half-length
model fabrication and the built model showed a goodquench performance. Only a remained problem is thecoil winding method. The coils for the model magnet were wound by hand, and considerable skill andtime were required. An automatic winding process iscurrently being developed.
Multipole components of the model magnet are
shown in Table 1. In the original design of this magnet,
it had been assumed to use two currents, 9 to 11 ratioof the current in cables. However, to simplify the system, it is decided to use uniform current instead of thetwo currents. Accordingly, in the cross-sectional magnet design, number of layers at the most inside slots,
closest to each poles, of both inner and outer coils was
reduced from 9 to 8 layers. The re-optimized values arealso indicated in Table 1. The calculated values werecomputed using 3D magnetic calculation by TOSCA.
According to the basic idea, if helical dipole magnets are employed for the Siberian Snake, deflectionsof beam orbits will be canceled due to 360 degree rotation of magnetic field. However, in actual magnets,
there are fringing fields and therefore 360 degree rotaTable 1. The multipole component at the center region of
the magnet.
Experiment
Fabricated half-length model-5.7 x 10-3
Sextupole (300Ncable)
6.4 x 10-4
Decapole (300Ncable)-6.2 x 10-'
Sextupole (l00Ncable)
7.6 x IO~
Decal!2le (l00Ncable~
Re-optimized design
Sextupole (300Ncable)
Decapole (300Ncable)
Sextupole (83Ncable)
Decapole (83Ncable)

Calculation-5.1 X 10-3
3.4 X 10-4
-5.3 X 10-'
6.2 x 10~
3.7 x IO ~-2.6 x IO~
6.0 x IO~
4.2 x 10-'

The above values are derived from the expansion of th e
azimuthal field component. The reference radius is set to 31 mm.

l.5 1Q4 ,......................,......."T""T'"'!"T""~~.......,"T""T'"r-:~..,.,""!"T;-]

!i

Il()4

5000

~

CIl

:9 -5000£-I 10'

Z-Positioo (em)Fig. 1. Vertical and horizontal components in a helical
dipole magnet.

tion does not always cancel the deflection of orbits. In
Fig. 1, a typical magnetic field of the full-length helicalsnake magnet is shown by vertical, By, and horizontal, B x , components. Applying the coordinates which
are used by this figure, a symmetry condition makes
an integral of Bx component along the beam axis automatically zero. Therefore, we have to pay attention
only to the By component, and have to optimize theintegral of this component to become zero in designing helical magnets. When this condition is achieved,
we may say that this magnet has effectively 360 degree of rotation angle. Table 2 shows the measured
and predicted transverse fields. The measured integrated field was constructed based on the Hall probe
scan over the half-length magnet. The body portion,
which shows a constant change of the phase angle of thedipole component, was extended to fit the full-length
magnet. The predicted values were calculated using
the TOSCA, where the re-optimized cross-section andslightly modified coil end design were taken into account. The modification of the coil ends is to matchwith the automatic winding. All these values are wellwithin the requirements from beam optics considerations. Furthermore, we can adjust the rotation angle
modifying the iron yoke length after the first measurement of the full-length helical dipole magnet.
The design of the full length helical dipole magnet
has been completed. The automatic winding method,which is a single remained issue of the magnet fabrication, is now in progress. The first full-length magnet
will be constructed and tested in this spring.
Table 2. The integrated transverse field.
Integral of Bx
Measured (220Ncable)
1.5 x 10Re-optimized (300Ncable)
Re-optimized (83Ncable)

3

Integral of By (Tm)
5.8 X 10-4
-6.9 x 10-4
2.0 x 10-4

251

VI.

RADIATION MONITORINGRIKEN Accel. Prog. Rep. 31 (1998)

Routine Works for Radiation Safety in
the Ring Cyclotron Facility
S. Fujita, S. Ito, S. Nakajima, H. Uehara,*l T. Arakawa,*2
Y. Uwamino, and N. Nakanishi
The radiation safety control system has worked wellsteadily during this year (1997) so as to enable us to
execute radiation monitoring service continuously andautomatically.
From the accumulated data of leakage neutrons, theradiation level in the controlled area was found muchless than the safety limit (0.3 mSv /week). Leakageof neutrons at the boundary of the accelerator facility has been recorded with the monitor installed in
the ground-floor computer room just above a bending
magnet that guides the beams from the Ring Cyclotron
vault to the distribution corridor. We found that theradiation level is much less than the safety limit (1mSv /year). Leakage of 'Y rays and neutrons were notpossible to detect with environmental monitors set outside the building during this reporting period.
A film badge (FB) with a Optical Character Reader(OCR)-code had been used to open the gate at theentrance of the controlled area, while a card with abar-code had been used to check a user and to open
the gate of experimental vaults. It sometimes caused
for users to forget or lose the card. In the last winter,
the FB system was replaced by a new type with a barcode. With this change, all of the OCR and bar-codecard readersl) were exchanged with new FB-readersof no contact type. So, there is no need for users tocarry the card, and the procedure to open the gate became simple. Moreover, the mechanical troubles havemuch decreased in the new FB-reader system, and theuser registration has also become easy. Figure 1 is thephotograph showing a new FB-reader system at theentrance gate for the controlled area, and Fig. 2 is thephotograph of showing new FB-readers on top of thegate-bar at the entrance of experimental vault.
In this winter-98, we are going to install a new handfoot-cloth monitor system at the entrance room forcontrolled area, which is able to detect f3( 'Y) and a
rays.

Fig. 1. Photograph of a new FB-reader system at theentrance gate for the controlled area.

Fig. 2. Photograph of new FB-readers on top of thegate-bar at the entrance of experimental vault.

References
1) S. Fujita and N. Nakanishi: RIKEN Accel. Prog. Rep.
28, 186 (1995).

* 1 Faculty of Science and Technology, Chuo University*2

Faculty of Science, Science University of Tokyo

253

RIKEN Accel. Prog. Rep. 31 (1998)

Dose Rates Due to Residual Radioactivity
in the Ring Cyclotron Facility
S. Fujita, H. Uehara,·1 T. Arakawa,·2 S. Ito, S. Nakajima, Y. Uwamino, and N. Nakanishi
Residual radioactivities were measured on the surface at various points by using ionization-chamber survey meters in the Ring Cyclotron Facility. The measurements were performed during the routine overhaul
period and after almost every beam time. In the following, we describe the significant dose rates observed
through measurements.
Just after the last beam time of the spring term, aroutine overhaul started. During the last beam timeof the spring term, an experiment with an 22Ne beamof 110 MeV/nucleon was carried out in the E6 experimental vault from August 1 to 8, 1997. The dose rates
in the Ring Cyclotron and the injector AVF cyclotron
were measured on Aug. 27 and 28, 1997 during theoverhaul period. The results are shown in Fig. 1 forthe Ring Cyclotron.

DOSE UNIT : /LSv/h

B e amFig. 2. Dose rates measured inside the injector AVF cyclotron. They are given in units of J.LSV Ih, and * indicates an extra measurement on December 25.
Table 1. Summary of the dose rates measured along thebeam lines with ionization-chamber survey meters. The
points a-z indicate the detection points shown in Fig. 3.
Detection Measured
point dose rate().lSv/h)

a
b

c
d

e
f
g
h

Fig. 1. Detection points around the RIKEN Ring
Cyclotron: EDC, the electrostatic deflection channel;
MDCl, the magnetic deflection channel 1; MDC2, themagnetic deflection channel 2; MDPl, the main differential probe 1; MDP2, the main differential probe 2;
MDP3, the main differential probe 3. Indicated numbers are dose rates in units of J.LSV Ih.

Besides the above routine measurement, dose rates
inside the AVF cyclotron were measured when its acceleration chamber was opened on December 25, '96
because of a trouble of insulation of the deflector in
vacuum. The results are shown in Fig. 2 for the injector AVF cyclotron.

j
k

m
n
0

P
q
r

s
t
u

v
w
X

Y
*1
*2

254

Faculty of Science and Technology, Chuo University
Faculty of Science, Science University of Tokyo

z

100
600
800
80
1000
350
130
350
70
550
130
120
160
200
1000
120
600
300
60
500
60000
50
1500
1200
50
180

Date

Mar 7, '97
Jun 17, '97
Jun 17, '97
Jun 17, '97
Jun 17, '97
Mar 7, '97
Oct 18, '96
Apr 25, '97
Oct 18, '96
Nov 13, '96
Aug 11, '97
Dec 18, '96
Sep 18, '97
Apr 28, '97
Aug 11, '97
Dec 18, '96
Feb 5, '97
Nov 13, '96
Nov 13, '96
Nov 13, '96
Nov 13, '96
Nov 27, '96
Nov 27, '96
Nov 27, '96
Feb 27, '97
Feb 27, '97

The experiment preceded
particle energy intensity period(MeV/n) (enA) (days)
3
C-13
115
1350
4
140
d
135
4
140
d
135
4
d
135
140
4
140
d
135
115
1350
3
C-13
4
1600
C-I3
100
Fe-56
90
200
3
4
C-13
100
1600
p
113
600
3
Ne-22
110
1900
8
Ne-22
1200
110
8
8
0-18
100
1800
Ne-22
110
1800
6
Ne-22
110
1900
8
Ne-22
110
1200
8
2
113
1360
P
113
600
3
P
3
113
600
P
p
113
600
3
113
600
3
p
4
N-I4
135
2000
4
N-I4
135
2000
N-14
135
2000
4
d
135
240
8
d
135
240
8

Fig. 3. Layout of the RIKEN Ring Cyclotron Facility as of 1997. Detection points ofresidual activities along the beam lines are denoted by a-z.

In the period from Oct. 1, 1996 to Sep. 30, 1997,
dose rates were measured along the beam lines. The
bulleted points a-z in Fig. 3 denote the places where
the dose rates exceeded 50 p,Sv /h. Table 1 summarizes

the observed dose rates with the dates on which themeasurements were performed. The maximum dose
rate was found to be 60 mSv/h (60,000 p,Sv/h) at thetarget chamber, denoted by the point u in Fig. 3.

255

RIKEN Accel. Prog. Rep. 31 (1998)

Residual Induced-Radioactivity at the Old 160 cm Cyclotron
Y. Uwamino, S. Ito, S. Shinohara, and K. Harasawa
Construction of the RI Beam Factory requires the removal of some of the old radiation facilities located adjacent to the existing ring cyclotron. They possess an
unsealed radioactivity-handling facility, small electrostatic accelerators, and an old 160-cm cyclotron. Only
the last one has been already shutdown though, it is
the most massive item and it still contains induced radioactivity.
The 160-cm cyclotron was built in 1966, operated
for 23 years with beams of proton to 2oNe, and was
shutdown in April 1990. The maximum energy was 17
MeV for protons and 160 MeV for 2oNe. The maximum beam intensity was 30 /-LA for protons and 0.3/-LA for 2oNe. The total weight of the magnet is 330
tons including the coil. 1 )For estimating the amount of radioactive waste fromthe 160-cm cyclotron, we took several samples from it,and measured them with a Ge detector for a gammaray spectrometry. The preliminary results of the measurement are shown in Table 1.
The measured radioactivity is only 60Co for the most
samples. However, the 55Pe and 63Ni radionuclides,
which cannot be detected by the Ge detector, are also
expected in the iron and copper material, respectively,
as speculated from the decommissioning experience 2)of the PM cyclotron at the Institute for Nuclear Study,
University of Tokyo. The amount of 63Ni can be estimated to be about 10 times higher than that of 60Co
in copper, but the radiation toxicity is 1/40 of 60Co.3)
Since the half life of 55Pe is shorter than 60Co and theradiation toxicity is 1/60 of 60Co, the effect of 55Pe canbe neglected.
There is no statement on the exemption limit against
the solid waste in the Japanese law. So, we cannot
consider any substances as non-radioactive waste if it
contains non-negligible amount of radioactivity. Considering the amount of radioactivity in the natural rockor soil, the concentration of 0.2 Bq/ g of 60Co can beconsidered as non-radioactive, and the radioactivity ofthis concentration can be detected by a handy scintillation survey meter. Compared with the exemption
limit of 1 Bq/g for 60Co in the Swiss legislation whichis adopted at CERN, our criterion may be too muchless than the reasonable value.

256

Table 1. Residual radioactivity measured in the old 160
cm cyclotron.
Eosition
earth platematerial nuclide activit~
oOCo
0.108q/g
Cuearth plate

Cu

6OCo

0.12

deflector

Cu

2078i
6.1Zn

5.23
2.10
1.14
22.24

22Na

6OCo
deflector

brass

6OCo

1.01

deflector

6OCo

10.53

extraction duct

SS
SS

6OCo

3.53

extraction duct

brass

6OCo

1.22

extraction duct

Fe

6OCo

0.37

extraction duct

Fe

6OCo

0.15

diffusion pump

Fe

6OCo

0.09

Dee

6OCo

15.67

Dee

SS
SS

6OCo

5.81

resonator

Fe

6OCo

0.06

resonator

SS?

6OCo

0.04

resonator meter

ferrite

6OCo

9.62

yoke

Fe

6OCo

0.4 1

yoke

Fe

6OCo

0 .83

Fe

6OCo

2.52

Eole tiE

On our criterion, the substances excepting the earth
plate, the diffusion pump, and the iron at resonatorare all treated as radioactive. In general, iron andcopper parts placed far from the beam orbit are nonradioactive, while almost all parts of the stainless-steel
are radioactive.
References
1) Y. Awaya et al., Ed.: RIKEN Accel. Prog. Rep. Suppl.
(1990).
2) "Production of induced radioactivity and its safe handling at accelerator facilities" , Report of the committee
for "Problems on induced radioactivity at accelerator
facilities", Japan Radioisotope Association (1994). (inJapanese)
3) Swiss Legislation on Radiological Protection, 814.501
Ordinance of 22 June 1994.

VII. LIST OF PUBLICATIONS
1.

Accelerator
physics

development

andaccelerator

Y. Yano and 1. Tanihata: "New application of radioisotopes at big accelerators", Radioisotopes, pp. 36-49(1995).
O. Kamigaito, A. Goto, Y. Miyazawa, T. Chiba, M.
Hemmi, M. Kase, S. Kohara, Y. Batygin, and Y.
Yano: "Development of a folded-coaxial RFQ linac
for the RILAC", Proc. 18th Int. Linear Accelerator
Conf., Geneva, Switzerland, Aug., edited by C. Hilland M. Vretenar, CERN, pp. 863-865 (1996).
Y. Yano: "RIKEN Ring Cyclotron: 10 years of progress, future development", Genshiryoku Kougyou,
pp. 42-53 (1997).
Y. Yano, A. Goto, and T. Katayama: "RIKEN RIBeam Factory Project", JARA J., 6, 1-9 (1997).
A. Goto, T. Kubo, H. Okuno, T. Kawaguchi, T.
Mitsumoto, T. Tominaka, S. Fujishima, J. W. Kim,
K. Ikegami, N. Sakamoto, S. Yokouchi, T. Morikawa,
K. Sugii, and Y. Yano: "The Booster Ring Cyclotrons for the RIKEN RI Beam Factory", Proc.
11th Symp. on Accelerator Science and Technology,
Harima, 1997-10, edited by Y. Miyahara, JASRI, pp.
53- 55 (1997).
O. Kamigaito, A. Goto, Y. Miyazawa, T. Chiba, M.
Hemmi, M. Kase, S. Kohara, T. Nakagawa, E.
Ikezawa, Y. Batygin, and Y. Yano: "Acceleration
tests of the folded-coaxial RFQ linac for the RILAC" ,Proc. 11th Symp. on Accelerator Science and Technology, Harima, 1997-10, edited by Y. Miyahara,
JASRI, pp. 92-94 (1997).
Y. Yano, A. Goto, and T. Katayama: "RIKEN RIBeam Factory Project", Proc. 11th Symp. on Accelerator Science and Technology, Harima, 1997-10,
edited by Y. Miyahara, JASRI, pp. 136-138 (1997).
Y. Batygin and T. Katayama: "Spin depolarization in presence of beam-beam interaction", Proc.
11th Symp. on Accelerator Science and Technology,
Harima, 1997-10, edited by Y. Miyahara, JASRI, pp.
282-284 (1997).
M. Takanaka and T. Katayama: "Simulation of beam
bunching using electron cooling for the ion storage
ring of RIKEN RI-Beam Factory Project", Proc.
11 th Symp. on Accelerator Science and Technology,
Harima, 1997-10, edited by Y. Miyahara, JASRI, pp.
291-293 (1997).
D. Toprek, A. Goto, and Y. Yano: "Beam orbit simulation in the central region of the RIKEN AVF
Cyclotron", Proc. 11th Symp. on Accelerator Science and Technology, Harima, 1997-10, edited by Y.
Miyahara, JASRI, pp. 537-539 (1997).
O. Kamigaito, A. Goto, Y. Miyazawa, T. Chiba, M.
Hemmi, S. Kohara, M. Kase, T. Nakagawa, Y.
Batygin, Y. Yano, E. Ikezawa, T. Aihara, T. Ohki,
H. Hasebe, and H. Yamauchi: "Acceleration tests ofthe folded-coaxial RFQ for the RILAC" , Proc. 22nd
Linear Accelerator Meet. in Japan, Sendai, 1997-09,
edited by Tohoku Univ., pp. 47-49 (1997).
A. Goto, T. Kubo, H. Okuno, T. Kawaguchi, T.
Mitsumoto, T. Tominaka, S. Fujishima, J. W. Kim,
K. Ikegami, N. Sakamoto, S. Yokouchi, T. Morikawa,Y. Tanaka, and Y. Yano: "The Superconducting
Ring Cyclotrons for RIKEN RI Beam Factory",
16th RCNP Osaka Int. Symp. on Multi-GeV HighPerformance Accelerators and Related Technology,
pp. 87-88 (1997).
Y. Yano: "RIKEN Ring Cyclotron: 10 years of progress, future development", Science & Technology inJapan, 1, 2-5 (1997).
Y. Batygin: "Dynamics of beam-beam interaction",
SPring-8 Proc. Workshop on Beam Physics, Hyogo,
1996-11, SPring-8, pp. 161-188 (1997).

2.

Nuclear physics and nuclear instrumentation

N. Hasebe, Y. Mishima, T. Do~e, J. Kikuchi, T.
Hayashi, T. Takashima, M. Kobayashi, N. Takehana,
H. Shirai, T. Yanagimachi, A. Nakamoto, H.
Murakami, K. Nagata, T. Kohno, K. Munakata,
C. Kato, S. Yanagita, Y. Yamada, M. Ehara, T.
Kashiwagi, T. Koi, J. Sequeiros, J. Medina, and B.
Wilken: "Composition and energy spectra of anomalous cosmic rays observed by the GEOTAIL satellite", Adv. Space Res., 19, 813-816 (1997).
H. Kurasawa and T. Suzuki: "Nuclear medium effects
to be observed and not to be observed", Genshikaku
Kenkyu 42,41-48 (1997).
T. Takashima, T. Doke, T. Hayashi, J.Kikuchi, K.
Itsumi, M. Kobayashi, H. Shirai, N. Takehana, N.
Hasebe, K. Kondoh, T. Kohno, K. Munakata, C.
Kato, S. Yanagita, Y. Yamada, D. Reames, andT. von Rosenvinge: "The first observation of sulfur in anomalous cosmic rays by the GEOTAIL andthe WIND spacecrafts" , 25th Int. Cosmic Ray Conf.
Contributed Papers, Vol. 2: Sessions SH4-6, Durban, South Africa, 1997-07, edited by Potgieter M.
S., Raubenheimer B. C., and van der Walt D. J.,
Potchefstroom Univ., pp. 285-288 (1997).
T. Kohno, 1. Yamagiwa, H. Miyasaka, T. Goka, and
H. Matsumoto: "Observation of heavy ions withADEOS satellite", 25th Int. Cosmic Ray Conf. Contributed Papers, Vol. 2: Sessions SH4-6, Durban,
South Africa, 1997-07, edited by Potgieter M. S.,
Raubenheimer B. C., and van der Walt D. J.,
Potchefstroom University, pp. 317-320 (1997).
G. I. Pugacheva, A. A. Gusev, T. Kohno, 1. M.
Martin, W. Spjeldvik, and T. Almand: "The 1-9
MeV /nucleon HE flux dynamics in the inner magnetosphere during 1984-1986", 25th Int. Cosmic Ray
Conf. Contributed Papers, Vol. 2: Sessions SH4-6,

257

Durban, South Africa, 1997-07, edited by Potgieter
M. S., Raubenheimer B. C., and van der Walt D. J.,
Potchefstroom University, pp. 353- 356 (1997).
Y. Muraki, K. Masuda, Y. Matsubara, T. Sako, 1.
Imaida, H. Tsuchiya, T. Kohno, T. Goka, H. Matsumoto, T. Omoto, Y. Fujiwara, K. Taguchi, M.
Nakazawa, I. Tanaka, M. Fujii, and H. Ikeda: "Scintillation fiber telescope for detecting neutrons in asatellite experiment", 25th Int. Cosmic Ray Conf.
Contributed Papers, Vol. 5: Sessions OG 10 & 11,
Durban, South Africa, 1997-07, edited by Potgieter
M. S., Raubenheimer B. C., and van der Walt D. J.,
Potchefstroom University, pp. 41-44 (1997).
M. Iwasaki, S. N. Nakamura, and T. Ito: "Precise measurement of X-rays in K-mesic hydrogen atom", Nihon Butsuri Gakkaishi 52, 272-275 (1997).
Y. Uwamino, T. Soewarsono, H. Sugita, Y. Uno, T.
Nakamura, T. Shibata, M. Imamura, and S. Shibata:"High-energy p- Li neutron field for activation experiment", Nuc!. Instrum. Methods Phys. Res. A 389,
463-473 (1997).
T. Ikeda, M. Chapman, Y. Igarashi, J. Imazato, J.
Lee, M. Khabibullin, O. Mineev, H. M. Shimizu,
S. Shimizu, A. Suzuki, A. Watanabe, and T. Yokoi:"High-precision magnetic field mapping with a threedimensional hall probe for a T-violation experimentin K/.L3 decay", Nucl. lnstrum. Methods Phys. Res.
A 401, 243-262 (1997).
S. Yamaji, F. A. Ivanyuk, and H. Hofmann: "Variationof transport coefficients for average fission dynamics
with temperature and shape", Nucl. Phys. A 612,
1-25 (1997).
D. Hirata, K. Sumiyoshi, 1. Tanihata, Y Sugahara,
T. Tachibana, and H. Toki: "A systematic study ofeven-even nuclei up to the drip lines within the relativistic mean field framework", Nucl. Phys. A 616,
438-445 (1997).
S. Frauendorf and J. Meng: "Tilted axis cranking intriaxial deformed nuclei", Nucl. Phys. A 617, 131147 (1997).
K. Sugawara-Tanabe and A. Arima: "New dynamical
SU(3) symmetry in deformed nuclei", Nucl. Phys. A
619, 88-96 (1997).
N. Dinh Dang, A. Arima, T. Suzuki, and S. Yamaji:"Study of Gamow-Teller resonance in 90Nb and 208Bi", Nucl. Phys. A 621, 719-735 (1997).
H. Akiyoshi: "Analyzing powers of proton-deuteronradiative capture reaction at 17.5 MeV", Nuclear
Study 42, 53-62 (1997).
K. Sakai, Y. Masuda, T. Adachi, K. Asahi, M. Doi,
M. Harada, S. Ishimoto, M. !inuma, J. Kura, A.
Masaike, Y. Matsuda, K. Morimoto, S. Muto, K.
Okumura, H. Sato, H. M. Shimizu, A. Yoshimi,
and Z. Zheng: "Observation of parity-violating neutron spin rotation in the n_ 139 La p-wave resonance",
Phys. Lett. B 391, 11-14 (1997).
T. Nakamura, T. Motobayashi, Y. Ando, A. Mengoni,
T. Nishio, H. Sakurai, S. Shimoura, T. Teranishi, Y.
258

Yanagisawa, and M. Ishihara: "Coulomb excitationof 11 Be", Phys. Lett. B 394, 11-15 (1997).
H. Kurasawa, K. Yabana, and T. Suzuki: "Damping width of the Mie Plasmon", Phys. Rev. B 56,
R10063- R10066 (1997).
F. A. Ivanyuk, H. Hofmann, V. V. Pashkevich , and S.
Yamaji: "Transport coefficients for shape degrees interms of Cassini ovaloids", Phys. Rev. C 55, 17301746 (1997).
N. Dinh Dang and F. Sakata: "Thermal damping
width of the giant dipole resonance in hot nuclei",
Phys. Rev. C 55, 2872-2884 (1997).
V. G. Soloviev, A. Arima, and N. Dinh Dang: "Possible enhancement of the El decay rates of double
giant dipole states", Phys. Rev. C 56, R603-R605(1997).
N. Dinh Dang, A. Arima, V. G. Soloviev, and S.
Yamaji: "Possible deviation of the sum of strengths
for the double giant dipole resonance from the harmonic oscillator limit", Phys. Rev. C 56, 1350-1356(1997).
J. Meng and P. Ring: "A giant halo at the neutron
drip line" , Phys. Rev. Lett. 79, 1234-1238 (1997).
N. Dinh Dang, A. Arima, T. Suzuki, and S. Yamaji:"Spreading of Gamow-Teller resonance in 90Nb and
208Bi'', Phys. Rev. Lett. 79, 1638-1641 (1997).
K. Kondoh, N. Hasebe, M. Kobayashi, J. Hamada,Y. Mishima, T. Doke, J. Kikuchi, T. Hayashi,
T. Takashima, N. Takehana, T. Yanagimachi, S.
Yanagita, Y. Yamada, K. Munakata, C. Kato, H.
Yanaizumi, K. Nagata, T. Koi, T. Kohno, and K.
Fujiki: "Interplanetary particle event related to cosmic ray modulation", Proc. 5th and 6th Symp. ofSolar Terrestrial Energy Program (STEP), Sendai,
1997, edited by H. Ohya, pp. 270-278 (1997).
A. Arima, N. Dinh Dang, T. Suzuki, and S. Yamaji:"Study of Gamow-Teller resonance in 208Bi taking
lplh-2p2h configuration mixing and ground-statecorrelations beyond RPA into account", Proc. Int.
Symp. on Non-Nucleonic Degrees of Freedom Detected in Nuclei (NNDF '96), Osaka, 1996-09, edited
by T. Minamisono, Y. Nojiri, T. Sato, and K.
Matsuta, World Scientific, pp. 361- 364 (1997).
H. Toki, K. Sumiyoshi, D. Hirata, Y Sugahara, and
1. Tanihata: "Relativistic many body theory for unstable nuclei and neutron stars", Proc. Int. Symp.
on Origin of Matter and Evolution of Galaxies in
the Universe, At ami , 1996, edited by T. Kajino, Y.
Yoshii, and S. Kubono, World Scientific, pp. 367-374(1997).
N. Dinh Dang, A. Arima, T. Suzuki, and S. Yamaji:"Spreading of Gamow-Teller resonance in 90Nb and
208Bi'', Proc. RlKEN Symp. on Giant Resonances,
Wako, 1997-01, edited by N. Dinh Dang and S.
Yamaji, pp. 30-38 (1997).
H. Kurasawa and T. Suzuki: "Double giant resonancestates" , Proc. RIKEN Symp. on Giant Resonances,
Wako, 1997-01, edited by N. Dinh Dang and S.

Yamaji, pp. 157-163 (1997).
H. Kurasawa and T. Suzuki: "Landau damping of the
Mie Plasmon", Soryushiron Kenkyu 95, B35-B38(1997).
J. Meng and P. Ring:"Relativisitic HartreeBogoliubov description of lithium isotopes", Z. Phys.
A 358, 123- 124 (1997).
K. Sugawara-Tanabe: "Magnetic dipole transitions inthe superdeformed bands of 193TI", Z. Phys. A 359,
9-10 (1997).
3.

Atomic and solid-state physics

G. Tatara, M. Matsuda, K. Katsumata, T. Kambara,
Y. Awaya, T. Mitamura, M. Terasawa, Y. Endoh,
K. Yamada, and S. Hosoya: "Bose-glass transition inheavy-ion irradiated La1.85SrO.15Cu04 single crystal", Czech. J. Phys. 46, s1555-s1556 (1996).
Y. Kino, M. R. Harston, I. Shimamura, E. A. G.
Armour, and M. Kamimura: "Asymptotic form of
three-body(dtp,)+ and (ddp,)+ wave functions", Hyperfine Interact. 101/102, 325-328 (1996) .
Y. Yamazaki: "Multiply charged ions, hollow atoms,
potential sputtering", Hyomen Kagaku 18, 752- 758(1997).
R. Kadono, 1. Watanabe, and K. Nagamine: "Quantum diffusion of positive muon in pure tantalum",
Hyperfine Interact. 105, 233- 237 (1997).
R. Kadono, R. M. Macrae, K. Nagamine, and K.
Nishiyama: "Mu centers in crystalline Ge under illumination" , Hyperfine Interact. 105, 303-308 (1997).
R. Kadono, R. M. Macrae, and K. Nagamine: "Muonium centers in heavily n-doped Si under illumination: Evidence for Mu-hole interaction", Hyperfine
Interact. 105, 327-331 (1997).
T. Kambara, A. Igarashi, N. Watanabe, Y. Nakai, T.
M. Kojima, and Y. Awaya: "Recoil-ion momentum
distribution of single-electron capture to the groundand exCited states in 0.5-1 MeV lu B4+,5+ -He collisions", J. Phys. B: At. Mol. Opt. Phys. 30, 12511260 (1997).
Y. Nakai, A. Itoh, T. Kambara, Y. Bitoh, and Y.
Awaya: "The fragment ion distribution of C 60 inclose collision with fast carbon ions" , J. Phys. B: At.
Mol. Opt. Phys. 30, 3049- 3058 (1997).
R . Kadono: "Muon spin relaxation in disordered spinpeierls system: Evidence for modulated antiferromagnetic ordering in CU1-c5Znc5Ge03", J. Phys. Soc.
Jpn. 66, 505-506 (1997).
K. Kawatsura, M. Sataka, M. Imai, K. Komaki, Y.
Yamazaki, K. Kuroki, Y. Kanai, S. Arai, and N.
Stolterfoht: "Low-energy Rydberg electron spectrafrom 64 MeV sq+ + He and C-foil collisions using
zero-degree electron spectroscopy", Nucl. Instrum.
Methods Phys. Res. B 124, 381-385 (1997).
H. Tawara, T. Azuma, T. Ito, K. Komaki, Y.
Yamazaki, T. Matsuo, T. Tonuma, K. Shima, A.
Kitagawa, and E. Takada: "X rays from radiativeIelectron capture into continuum states in relativistic heavy-ion collisions", Phys. Rev. A 55, 808-811(1997).
1. Kink, R. Hutton, B. Nystrom, 1. Martinson, K. Ishii,
K. Ando, T. Kambara, Y. Nakai, T. M. Kojima, andY. Awaya: "Lifetime of the 3p 2P3/2 level in Na-likeKr 25 +" , Phys. Rev. A 55, 3229-3232 (1997).
M. R. Harston, S. Hara, Y. Kino, 1. Shimamura, H.
Sato, and M. Kamimura: "Effects of the finite size ofthe ion (dd/L) + on the energy levels of the molecules(dd/L)e and (dd/L)dee", Phys. Rev. A 56, 2685-2691(1997).
V. I. Korobov and 1. Shimamura: "Auger transition
rates for metastable states of antiprotonic helium
He+p", Phys. Rev. A 56, 4587-4594 (1997).
A. Igarashi and I. Shimamura: "~wave resonances inpositron scattering by He+", Phys. Rev. A 56, 47334736 (1997).
R. Kadono, R. M. Macrae, K. Nishiyama, and K.
N agamine: "Evidence for muonium passivation in
n-doped Ge", Phys. Rev. B 55, 4035-4038 (1997).
A. Yamashita, K. Ishii, T. Yokoo, J. Akimitsu, M.
Hedo, Y. Inada, Y. Onuki, E. Yamamoto, Y. Haga,
and R. Kadono: "Anomalous field dependence ofmagnetic penetration depth in the vortex state of
CeRu2", Phys. Rev. Lett. 79, 3771-3774 (1997).
R. Hutton, I. Martinson, B. Nystrom, K. Ando, Y.
Awaya, P. K. Bengtsson, T. Kambara, Y. Kanai, T.
M. Kojima, Y. Nakai, K. Ishii, and M. Jager: "Intercombination transitions in beryllium-like and boronlike iron", Phys. Scr. 55, 431-433 (1997).
K. Ishii, T. Nishida, Y. Kimura, M. Fujiwara, T.
Nakano, S. Kawae, K. Ando, and T. Kambara:"Beam-foil spectra of highly-charged neon ions invisible region" , Phys. Scr., Omiya, 1996-09, edited by
Y. Awaya and T. Kambara, Royal Swedish Academyof Sciences, T73, 73-74 (1997).
K. Ishii, T. Nishida, Y. Kimura, S. Kawae, T . Nakano,
K. Ando, and Y. Awaya: "Beam-foil spectra ofhighly-charged argon ions in visible region", Phys.
Scr., Omiya, 1996-09, edited by Y. Awaya and T.
Kambara, Royal Swedish Academy of Sciences, T73,
75-76 (1997).
P. K. Bengtsson, K. Ando, T. Kambara, Y. Awaya,
and R. Hutton: "Intercombination lines in highly
charged Al- and Si-like ions", Phys. Scr., Omiya,
1996-09, edited by Y. Awaya and T. Kambara, Royal
Swedish Academy of Sciences, T73, 81-82 (1997).
T . Kambara: "Recoil-ion momentum spectroscopy offast collisions with HCI", Phys. Scr., Omiya, 199609, edited by Y. Awaya and T. Kambara, Royal
Swedish Academy of Sciences, T73, 162-166 (1997).
T. Mitamura, M. Terasawa, X. J. Fan, T. Kohara,
K. Veda, T. Kambara, Y. Awaya, · M. Matsuda,
G. Tatara, N. Takezawa, and K. Fukushima: "Swiftheavy-ion irradiation effects on the super-conducting
material La1.85SrO.15Cu04", Phys. Scr., Omiya,
1996-09, edited by Y. Awaya and T. Kambara, Royal259

Swedish Academy of Sciences, T73, 337-339 (1997).
M. Matsuda, G. Tatara, K. Katsumata, T. Kambara,
Y. Awaya, T. Mitamura, M. Terasawa, K. Yamada,
Y. Endoh, and S. Hosoya: "Swift heavy-ion irradiation effects on the single crystal La1.85SrO.15Cu04" ,Phys. Scr., Omiya, 1996-09, edited by Y. Awaya and
T. Kambara, Royal Swedish Academy of Sciences,
T73, 340-342 (1997).
X. J. Fan, M. Terasawa, T. Mitamura, T. Kohara,
K. Ueda, H. Tsubakino, T. Kambara, Y. Awaya,
M. Matsuda, G. Tatara, K. Fukushima, and
N. Takezawa: "Suppression of vortex motion in
La1.85SrO.15Cu04 with the splayed configuration ofcolumnar defects", Physica C 282/287, 2105-2106(1997).
K. Kawatsura, H. Kageyama, R. Takahashi, D.
Hamaguchi, S. Arai, Y. Aoki, S. Yamamoto, H.
Takeshita, H. Naramoto, T. Kambara, M. Oura,Y. Kanai, and Y. Awaya: "Copper L X-ray spectra measured by a high resolution ion-induced X-ray
spectrometer", Radiat. Phys. Chern. 49, 617-622(1997).

4.

Radiochemistry, radiation chemistry, and radiation biology

R. Amano, S. Oishi, S. Enomoto, and F. Ambe:"Unique behavior of rubidium in mice under low oxygen atmosphere", Ann. Clin. Lab. Sci. 27, 358-364(1997).
R. Hirunuma, K. Endo, M. Yanaga, S. Enomoto, S.
Ambe, A. Tanaka, M. Tozawa, and F. Ambe: "Theuse of a multitracer technique for studies of the uptake and retention trace elements in rats" , Appl. Radiat. Isot. 48, 727-733 (1997).
Y. Itoh, Z. Peng, K. Lee, M. Ishii, A. Goto, N.
Nakanishi, M. Kase, and Y. Ito: "Slow positron
beam production by irradiation of p+, d+, and He2 +on various targets", Appl. Surf. Sci. 116, 68-72(1997).
M. Suzuki, Y. Kase, T. Kanai, F. Yatagai, and M.
Watanabe: "LET dependence of cell death andchromatin-break induction in normal human cells irradiated by neon-ion beams", Int. J. Radiat. BioI.
72, 497- 503 (1997).
R. Hirunuma, N. Sotogaku, K. Endo, S. Enomoto, S.
Ambe, and F. Ambe: "Application of the multitracer
technique: Metabolic study of trace elements in Sedefficient rats", J. Inorg. Biochem. 67, 22 (1997).
N. Sotogaku, R. Hirunuma, K. Endo, S. Enomoto, S.
Ambe, and F. Ambe: "Study of the binding of various trace elements to blood components and serum
proteins by mean of the multitarcer technique", J.
Inorg. Biochem. 67, 23 (1997).
S. Enomoto, R. G. Weginwar, R. Hirunuma, S. Ambe,and F. Ambe: "Metabolic study of trace elementsin acute alcoholic mice", J. Inorg. Biochem. 67, 27(1997).
260

S. Enomoto, B. Liu, S. Ambe, R. Amano, and F.
Ambe: "Accumulation of inorganic elements in ddYmice implanted with Ehrlich sarcoma", J. Inorg.
Biochem. 67, 28 (1997).
N. Hayakawa, S. Enomoto, R. Hirunuma, K. Endo,
S. Ambe, and F. Ambe: "Metabolic study of traceelements in liver cancer bearing rats", J. Inorg.
Biochem. 67, 29 (1997).
T. Ozaki, S. Enomoto, Y. Minai, S. Ambe, F. Ambe,and T. Tominaga: "Determination of lanthanides
and other trace elements in ferns by instrumental
neutron activation analysis", J. Radioanal. N ucl.
Chern. 217, 117-124 (1997).
B. Liu, S. Ambe, S. Enomoto, R. G. Weginwar, and
F. Ambe: "Preparation of carrier-free group tracers
from a gold target irradiated by high-energy heavyions", J. Radioanal. Nucl. Chern. 223, 3-7 (1997).
K. Eguchi-Kasai and H. Ohara: "Effect of particle irradiation on cell cycle progression", J pn. J. Cancer
Clin. 43,201- 204 (1997).
T. Nozaki, Y. Itoh, Z. Peng, Y. Ito, N. Nakanishi,
H. Yoshida, and A. Goto: "Preparation of positronsource for slow positron beam by ion bombardment on liquid and gas targets", Mater. Sci. Forum,
255/257, 799-801 (1997).
H. Wang, S. Ambe, N. Takematsu, and F. Ambe:"Model study of influence of acid rain on adsorptive
behavior of trace elements on soil by the multitracer
technique", Proc. Int. Congr. of Acid Snow and Rain
1997, Niigata, 1997-10, edited by K. Aoyama, K.
Katoh, T. Murano, T. Paces, and Y. Taguchi, pp.
363-368 (1997).
H. Sasaki, F. Yatagai, T. Kanai, Y. Furusawa, F.
Hanaoka, W. Zhu, and P. Mehnati: "Dependence
of induction of interphase death of Chinese hamster ovary cells exposed to accelerated heavy ions on
linear energy transfer", Radiat. Res. 148, 449-454(1997).
Y. Takahashi, Y. Minai, S. Ambe, Y. Makide, F.
Ambe, and T. Tominaga: "Simultaneous determination of stability constants of humate complexes withvarious metal ions using multitracer technique" , Sci.
Total Environ. 198, 61- 71 (1997).
S. Enomoto, B. Liu, R. G. Weginwar, S. Ambe, and
F. Ambe: "Distribution and pathological studies on
rare-earth elements in non-insulin dependent diabetes mellitus mice", Trace Elem. Man Anim. (Proc.
Int. Symp. on Trace Elements in Man and Animals,9th) 9, 347-348 (1997).
S. Enomoto, B. Liu, R. G. Weginwar, S. Ambe, and F.
Ambe: "Multitracer study on the uptake of inorganic
ions by tumor", Trace Elem. Man Anim. (Proc. Int.
Symp. on Trace Elements in Man and Animals, 9th)
9, 363-364 (1997).
S. Enomoto, R. G. Weginwar, B. Liu, S. Ambe, and
F. Ambe: "Biodistribution of gold complexes inmice" , Trace Elem. Man Anim. (Proc. Int. Symp. onTrace Elements in Man and Animals, 9th) 9, 568569 (1997).

5.

Material analysis

Z. Peng, Y. Itoh, S. Q. Li, and S. Wang: "Study of ionictransport in polymer electrolyte using positron lifetime distribution method", Appl. Phys. A 63, 267270 (1996).
A. Kinoshita:
Y. Itoh, H. Murakami, and"Positron/ positronium annihilation in low dimensional silicon materials", Appl. Surf. Sci. 102, 423426 (1996).
K. Maeda, H. Hamanaka, and K. Hasegawa: "High resolution PIXE using crystal spectrometer combinedwith position sensitive detectors", Int. J. PIXE, 6,
97-116 (1996).
J. Kawai, H. Adachi, Y. Kitajima, K. Maeda, S.
Hayakawa, and Y. Gohshi: "Inelastic mean free pathof photoelectrons in Ag determined by total reflection X-ray photoelectron spectroscopy", Anal. Sci.
13, 797-801 (1997).
K. Maeda and K. Hasegawa: "High-resolution PIXE
analysis using a position-sensitive crystal spectrometer" , loniz. Radiat. (Tokyo) 23, 9-19 (1997).
W. Hong, S. Hayakawa, K. Maeda, S. Fukuda, M.
Yanokura, M. Aratani, K. Kimura, Y. Gohshi, and
I. Tanihata: "Improvement in the detection limitsof elastic recoil detection analysis (ERDA) using atime-of-flight detection", Jpn. J. Appl. Phys. 36,
L952-L954 (1997).
W. Hong, S. Hayakawa, K. Maeda, S. Fukuda, M.
Yanokura, M. Aratani, K. Kimura, Y. Gohshi, and
1. Tanihata: "Determination of the mass resolution
and the depth resolution of time of flight elastic recoil detection analysis using heavy ion beams", J pn.
J. Appl. Phys. 36, 5737-5740 (1997).
Y. Itoh, H. Murakami, H. Takeno, S. Ushio, and T.
Takenaka: "Positron lifetime in floating-zone-grownsilicon water", Mater. Sci. Forum, 255/257, 545547 (1997).
W. Hong, S. Hayakawa, K. Maeda, S. Fukuda, M.
Yanokura, M. Aratani, K. Kimura, Y. Gohshi, and
1. Tanihata: "Development of a high mass-resolution
TOF-ERDA system for a wide mass range", Nucl.
Instrum. Methods Phys. Res. B 124, 95-99 (1997).
K. Maeda: "Water analysis by PIXE" , Proc. 34th Seminar on Science and Technology, Small Accelerators& Their Application, Tokyo, 1997-02, Interchange
Association, pp. 171-178 (1997).
H. Hamanaka, K. Hasegawa, and K. Maeda: "Application of a position-sensitive X-ray detector to highresolution PIXE measurements", Proc. 34th Seminar on Science and Technology, Small Accelerators& Their Application, Tokyo, 1997-02, Interchange
Association, pp. 295-300 (1997).

261

VIII. LIST OF PREPRINTS
1997

RIKEN-AF-NP
249 N. Hayashi, Y. Goto, and N. Saito: "Possible measurements of the gluon polarization in the nucleon with

PHENIX detector system"
250 Y. Mochizuki, K. Oyamatsu, and T. Izuyama: "Exotic nuclear rod formation induced by superfluid vortices

in neutron star crusts"
251 N. Saito: "Spin physics at RHIC"
252 V. G. Soloviev, A. Arima, and N. Dinh Dang: "On a possible enhancement of the El decay rates of double

giant dipole states"
253 K. K. Korsheninnikov, E. A. Kuzmin, E. Yu. Nikolskii, O. V. Bochkarev, S. Fukuda, S. A. Goncharov, S.
Ito, T. Kobayashi, S. Momota, B. G. Novatskii, A. A. Ogloblin, A. Ozawa, V. Privora, I. Tanihata, and K.
Yoshida: "The L = 1 excitation in the halo nucleus 11 Li"
254 T. Suzuki and T. Otsuka: "Gamow-Teller transitions from 11Li and 12Be"
255 N. Dang, A. Arima, V. G. Soloviev, and S. Yamaji: "Possible deviation of the sum of strengths for double

giant dipole resonance from harmonic oscillators's limit"
256 T. Teranishi, S. Shimoura, Y. Ando, M. Hirai, N. Iwasa, T. Kikuchi, S. Moriya, T. Motobayashi, H.

Murakami, T. Nakamura, T. Nishio, H. Sakurai, T. Uchibori, Y. Watanabe, Y. Yanagisawa, and M. Ishihara:"Isobaric analog state of 11 Li"
257 K. Varga and Y. Suzuki: "Solution of few-body problems with the stochastic variational method: I. Central
forces"258 L. Va. Glozman, W. Plessas, K. Varga, and R. F. Wagenbrunn: "Unified description of light- and strange-

baryon spectra"
259 J. Meng, 1. Tanihata, and S. Yamaji: "The proton and neutron distribution in Na isotopes: The developmentof halo and shell structure"
260 H. Kurasawa and T. Suzuki: "Nuclear response to electromagnetic field"

261 H. Kurasawa: "Double giant resonance states"
262 H. Kurasawa and T. Suzuki: "Nuclear medium effects to be observed and not to be observed"
263 H. Kurasawa and T . Suzuki: "The continuity equation of RPA"

264 H. Kurasawa, K. Yabana, and T. Suzuki: "Damping width of the Mie Plasmon"
265 M. R. Ahmady, E. Kou, and A. Sugamoto: "Intermediate psuedoscalar resonanse contributions to B -+ Xs,

gamma, gamma"
266 Y. S. Mochizuki, T. Izuyama, and 1. Tanihata: "Dynamics of exotic nuclear rod formation for neutron starglitches"
267 K. Oyamatsu, 1. Tanihata, Y. Sugahara, K. Sumiyoshi, and H. Toki: "Can the equation of state of asym-

metric nuclear matter be studied using unstable nuclei?"262

268 D. Hirata, K. Sumiyoshi, 1. Tanihata, Y. Sugahara, and H. Toki: "Systematic study of even-even nuclei up
to the drip lines in terms of relativistic many body framework"
269 N. D. Dang and A. Arima: "Quantal and thermal dampings of giant dipole resonance in 90Zr, 120Sn and
208Pb''
270 N. D. Dang and A. Arima: "Temperature dependence of quantal and thermal dampings of the hot giant
dipole resonance"
271 M. Oi, N. Onishi, N. Tajima, and T. Horibata: "Signature and angular momentum in 3d-cranked HFBstates"272 J. Meng, K. Sugawara-Tanabe, S. Yamaji, P. Ring, and A. Arima: "The pseudo-spin symmetry in realistic
nuclei"
273 N. D. Dang and F. Sakata: "Relation between the damping hot giant dipole resonance and the complex
admittance of an irreversible process"274 M. R. Ahmady, E. Kou, and A. Sugamoto: "Non-spectator contribution: A mechanism for inclusive B -+Xsn' and exclusive B -+ K( *)n' decays"
275 H. Okamura, S. Ishihara, N. Sakamoto, H. Otsu, T. Uesaka, T. Wakasa, Y. Satou, H. Sakai, T. Niizeki, H.
Ohmura, and T. Ichihara: "Detector system of the first focal-plane of the spectrometer SMART at RIKEN"
276 A. Arima: "Dynamical symmetries and nuclear structure"
277 S. Nagataki, M. Hashimoto, K. Sato, S. Yamada, and Y. S. Mochizuki: "High ratio of 44Tij 56 Ni in Cas A
and axiaymmetric collapse-driven supernova explosion"

RIKEN-AF-NC

ohkawa , M. Takanaka, M. Wakasugi, S. Watanabe, Y.
Yano, K. Yoshida, J. Xia, Y. Rao, and Y. Yuan: "Muses project at RIKEN RI Beam Factory"

1 T . Katayama, Y. Batygin, N. Inabe, K. Ohtomo, T.

2 1. Meshkov: "Physics and technique of electron cooling"
3 Y. K. Batygin and T. Katayama: "Noise instability in nonlinear beam-beam interaction"

263

IX. PAPERS PRESENTED AT MEETINGS
1.

Accelerator
physics

development

andaccelerator

Y. Yano: "RI Beam Factory and its expected pioneering work", 22nd Japan Conf. on Radiation and Radioisotopes, Yokohama, Dec. (1996).
A. Goto, T. Kubo, H. Okuno, T. Kawaguchi, T.
Mitsumoto, T. Tominaka, S. Fujishima, J. W. Kim,
K. Ikegami, N. Sakamoto, S. Yokouchi, T. Morikawa,Y. Tanaka, and Y. Yano: "The Superconducting
Ring Cyclotrons for RIKEN RI Beam Factory",
16th RCNP Osaka Int. Symp. on Multi-GeV HighPerformance Accelerators and Related Technology,(RCNP, Osaka Univ.), Osaka, Mar. (1997).
J. W. Kim: "Accelerator technology at RIKEN",
Symp. on Accelerator Transmutation Technology'97, (Electrical Engineering and Science Research Institute), Seoul, Korea, Apr. (1997).
M. Takanaka and T. Katayama: "Simulation of beam
bunching with electron cooling for the ion storage
ring of RIKEN RI-Beam Factory Project" , 1997 Particle Accelerator Conf. (PAC '97), (TRIUMF), Vancouver, Canada, May (1997).
T. Kawaguchi, T. Kubo, T. Mitsumoto, H. Okuno, T.
Tominaka, J. W. Kim, S. Fujishima, K. Ikegami, N.
Sakamoto, S. Yokouchi, T. Morikawa, Y. Tanaka, A.
Goto, and Y. Yano: "Design of the sector magnets
for the RIKEN Superconducting Ring Cyclotron",1997 Particle Accelerator Conf. (PAC '97), (TRIUMF), Vancouver, Canada, May (1997).
Y. Yano, A. Goto, and T. Katayama: "RIKEN RIBeam Factory Project", 1997 Particle Accelerator
Conf. (PAC '97), (TRIUMF), Vancouver, Canada,
May (1997).
T. Tominaka, M. Okamura, and T. Katayama: "Analytical field calculation of helical dipole magnets for
RHIC" , 1997 Particle Accelerator Conf. (PAC '97),(TRIUMF), Vancouver, Canada, May (1997).
T. Tominaka, K. Hatanaka, and T. Katayama: "Multipole expansion for a single helical current conductor", 1997 Particle Accelerator Conf. (PAC '97),(TRIUMF), Vancouver, Canada, May (1997).
T. Tominaka, H. Okuno, S. Fujishima, T. Mitsumoto,T. Kubo, T. Kawaguchi, Y. Tanaka, J. W. Kim, K.
Ikegami, N. Sakamoto, S. Yokouchi, T. Morikawa, A.
Goto, and Y. Yano: "Design study of the injectionand extraction elements for the RIKEN Superconducting Ring Cyclotron", 1997 Particle Accelerator
Conf. (PAC '97), (TRIUMF), Vancouver, Canada,
May (1997).
T. Mitsumoto, A. Goto, T. Kawaguchi, J. W. Kim,
Y. Tanaka, T. Kubo, H. Okuno, T. Tominaka, S.
Fujishima, K. Ikegami, N. Sakamoto, T. Morikawa,
S. Yokouchi, and Y. Yano: "Orbit analysis for
the RIKEN Superconducting Ring Cyclotron", 1997
264

Particle Accelerator Conf. (PAC '97), (TRIUMF),
Vancouver, Canada, May (1997).
S. Fujishima, H. Okuno, T. Tominaka, T. Mitsumoto,T. Kubo, T. Kawaguchi, J. W. Kim, K. Ikegami, N.
Sakamoto, S. Yokouchi, T. Morikawa, Y. Tanaka, A.
Goto, and Y. Yano: "Numerical analyses of the injection and extraction trajectories for the RIKEN Superconducting Ring Cyclotoron", 1997 Particle Accelerator Conf. (PAC '97), (TRIUMF), Vancouver,
Canada, May (1997).
O. Kamigaito, A. Goto, Y. Miyazawa, T. Chiba, M.
Hemmi, M. Kase, S. Kohara, Y. Batygin, and Y.
Yano: "Acceleration test of the folded-coaxial RFQ
linac for the RILAC", 1997 Particle Accelerator
Conf. (PAC '97), (TRIUMF), Vancouver, Canada,
May (1997).
O. Kamigaito, A. Goto, Y. Miyazawa, T. Chiba, M.
Hemmi, S. Kohara, M. Kase, T. Nakagawa, Y.
Batygin, Y. Yano, E. Ikezawa, T. Aihara, T. Ohki,
H. Hasebe, and H. Yamauchi: "Acceleration tests ofthe folded-coaxial RFQ for the RILAC" , 22nd Linear
Accelerator Meet. in Japan, (Tohoku Univ.), Sendai,
Sept. (1997).
Y. Mizutani, K. Hori, T. Yamamoto, M. Miki, Y.
Izumi, S. Seki, T. Kozawa, K. Ushida, Y. Yoshida,
and S. Tagawa: "Development of a pulse radiolysis system by using picosecond electron pulses andfemtosecond laser pulses", 22nd Linear Accelerator Meet. in Japan, (Tohoku Univ.), Sendai, Sept.
(1997).
M. Kase, M. Kobayashi, A. Yoneda, and 1. Yokoyama:"Beam diagnostic instruments for RIKEN Ring Cyclot ron" , 3rd European Workshop on Beam Diagnostics and Instrumentation for Particle Accelerators,(LNF-INFN Frascati), Frascati, Italy, Oct. (1997).
T. Kawaguchi, J. W. Kim, T. Kubo, Y. Imai, andT. Minato: "A 6T He-free superconducting solenoid
for RI beam production", 15th Int. Conf. on Magnet Technology (MT15), (Institute of Electrical Engineering), Beijing, China, Oct. (1997).
T. Kawaguchi, T. Kubo, T. Mitsumoto, H. Okuno, T.
Tominaka, J. W. Kim, S. Fujishima, K. Ikegami, N.
Sakamoto, S. Yokouchi, T. Morikawa, Y. Tanaka, A.
Goto, and Y. Yano: "Design of the sector magnets
for the RIKEN Superconducting Ring Cyclotron",15th Int. Conf. on Magnet Technology (MT15), (Institute of Electrical Engineering), Beijing, China,
Oct. (1997).
T. Tominaka, H. Okuno, S. Fujishima, A. Goto, and Y.
Yano: "Relation between field homogeneity and multipole coefficients for dipole coils" ,15th Int. Conf. on
Magnet Technology (MT15), (The Institute of Electrical Engineering), Beijing, China, Oct. (1997).
M. Takanaka and T. Katayama: "Simulation of beam
bunching using electron cooling for the ion storage ring of RIKEN RI-Beam Factory Project",11th Symp. on Accelerator Science and Technology,(JASRI), Harima, Oct. (1997).
Y. Yano, A. Goto, and T. Katayama: "RIKEN RIBeam Factory Project", 11th Symp. on Accelerator Science and Technology, (JASRI), Harima, Oct.
(1997).
O. Kamigaito, A. Goto, Y. Miyazawa, T. Chiba, M.
Hemmi, M. Kase, S. Kohara, T. Nakagawa, E.
Ikezawa, Y. Batygin, and Y. Yano: "Acceleration
tests of the folded-coaxial RFQ linac for the RILAC" ,11 th Symp. on Accelerator Science and Technology,(JASRI), Harima, Oct. (1997).
N. FUkunishi, M. Kobayashi, A. Yoneda, M. Kidera,
M. Kase, and Y. Yano: "Heavy ion microbeam
project in RIKEN Ring Cyclotron", 11th Symp.
on Accelerator Science and Technology, (JASRI),
Harima, Oct. (1997).
A. Yoneda, H. Kumagai, M. Kobayashi, M. Kidera,
M. Kase, A. Goto, and Y. Yano: "New emittancemeasurement using two PPACs", 11th Symp. on Accelerator Science and Technology, (JASRI), Harima,
Oct. (1997).
M. Kase, A. Goto, T. Kageyama, I. Yokoyama, M.
Nagase, S. Kohara, T. Nakagawa, N. Inabe, K.
Ikegami, O. Kamigaito, M. Kidera, J. Fujita, and Y.
Yano: "Status report on RIKEN Ring Cyclotron",11th Symp. on Accelerator Science and Technology,(JASRI), Harima, Oct. (1997).
M. Kobayashi, A. Yoneda, M. Kase, M. Kidera, A.
Goto, and Y. Yano: "Phase stabilization of injection beam to RIKEN Ring Cyclotron", 11th Symp.
on Accelerator Science and Technology, (JASRI),
Harima, Oct. (1997).
T. Mitsumoto, A. Goto, T. Kawaguchi, J. W. Kim,
Y. Tanaka, T. Kubo, H. Okuno, T. Tominaka, S.
FUjishima, K. Ikegami, N. Sakamoto, T. Morikawa,
S. Yokouchi, K. Sugii, and Y. Yano: "Orbit analysis
for the RIKEN Superconducting Ring Cyclotron",11th Symp. on Accelerator Science and Technology,(JASRI), Harima, Oct. (1997).
S. Fujishima, H. Okuno, T. Tominaka, T. Mitsumoto,T. Kubo, T. Kawaguchi, J. W. Kim, K. Ikegami,
N. Sakamoto, K. Sugii, T. Morikawa, Y. Tanaka, T.
Wad a , A. Goto, and Y. Yano: "Analysis of the injection and extraction trajectories in the RIKEN Superconducting Ring Cyclotron", 11th Symp. on Accelerator Science and Technology, (JASRI), Harima,
Oct. (1997).
S. Kohara, Y. Miyazawa, O. Kamigaito, and A. Goto:"Design of a resonator for a flat-top acceleration system in the RIKEN AVF Cyclotron", 11th Symp.
on Accelerator Science and Technology, (JASRI),
Harima, Oct. (1997).
Y. Mizutani, K. Hori, T. Yamamoto, M. Miki, Y.
Izumi, S. Seki, T. Kozawa, K. Ushida, Y. Yoshida,
and S. Tagawa: "Development of a pulse radiolysis system by using picose,c ond electron pulses andfemtosecond laser pulses", 11th Symp. on Accelera-

tor Science and Technology, (JASRI), Harima, Oct.
(1997).
Y. Mizutani, K. Hori, T. Yamamoto, M. Miki, Y.
Izumi, S. Seki, T. Kozawa, K. Ushida, Y. Yoshida,
and S. Tagawa: "Development of a pulse radiolysis system by using picosecond electron pulses andfemtosecond laser pulses", 40th Symp. on Radiation
Chemistry, (Radiation Chemical Society of Japan),
Tokaimura, Oct. (1997).
T. Kawaguchi, H. Okuno, A. Goto, Y. Yano, andB. Ikeda: "Quench stabilities of Al stabilized superconducting wires for a superconducting ring cyclotron", 57th Meet. on Cryogenics and Superconductivity, (Cryogenics and Superconductivity Engineering Conference of Japan), Takamatsu, Nov.
(1997).
T. Tominaka, T. Kawaguchi, M.Okamura, and T.
Katayama: "Magnetic measurement of a helical
dipole magnet", 57th Meet. on Cryogenics and Superconductivity, (Cryogenics and Superconductivity
Engineering Conference of Japan), Takamatsu, Nov.
(1997).
T. Tominaka, H. Okuno, S. Fujishima, A. Goto, and Y.
Yano: "Relation between field uniformity and multipole coefficients", 57th Meet. on Cryogenics and Superconductivity, (Cryogenics and Superconductivity
Engineering Conference of Japan), Takamatsu, Nov.
(1997).

2.

Nuclear physics and nuclear instrumentation

H. Kurasawa and T. Suzuki: "Double giant resonancestates" , RIKEN Symp. on Giant Resonances, Wako,
Jan. (1997).
M. Kobayashi, T. Doke, J. Kikuchi, T. Hayashi, T.
Takashima, N. Takehana, H. Shirai, N. Hasebe,
K. Kondoh, T. Kashiwagi, T. Yanagimachi, A.
Nakamoto, H. Murakami, T. Kohno, K. Munakata,
C. Kato, S. Yanagita, Y. Yamada, and M. Ehara:"A relation between solar wind and CIR particles
observed by GEOTAIL satellite", 52nd Ann. Meet.
of Physical Society of Japan, Nagoya, Mar. (1997).
R. Susukita: "Observation by means of arrival times of
Cherenkov protons using the CANGAROO telescope", 52nd Ann. Meet. of Physical Society of Japan,
Nagoya, Mar. (1997).
I. Imaida, Y. Muraki, Y. Matsubara, K. Masuda,
T. Sako, T. Goka, H. Matsumoto, T. Omoto, Y.
Fujiwara, K. Taguchi, M. Nakazawa, I. Tanaka, M.
Fujii, T. Kohno, and H. Ikeda: "Accelerator beam
experiment of multi-anode neutron sensor", 52nd
Ann. Meet. of Physical Society of Japan, Nagoya,Mar. (1997).
T. Takashima, T. Doke, J. Kikuchi, T. Hayashi, M.
Kobayashi, N. Takehana, H. Shirai, S. Miyatani,
N. Hasebe, K. Kondohj T. Kashiwagi, T. Yanagimachi, A. Nakamoto, H. Murakami, T. Kohno, K.
Munakata, C. Kato, S. Yanagita, Y. Yamada, and M.
265

Ehara: "Time variation of particle (10-30 MeV In)
intensity observed by GEOTAIL-HEP", 52nd Ann.
Meet. of Physical Society of Japan, Nagoya, Mar.
(1997) .
H. Kurasawa and T. Suzuki: "Nuclear medium effects to be observed and not to be observed", Int.
Workshop on Nuclear Medium Effect via Nucleon Induced Reaction, (RCNP, Osaka Univ.), Kyoto, Mar.
(1997) .
H. Kurasawa, K. Yabana, and T. Suzuki: "The widthof the Mie Plasmon", Structure of Atomic Clusters,(Kyoto Univ.), Kyoto, Mar. (1997).
Y. Watanabe: "Survey of DVD as a large scale data
storage system", Computing Research Center Seminar, (KEK), Tsukuba, May (1997).
E. Kim, T. Nakamura, Y. Uwamino, M. Imamura, N.
Nakao, and S. Tanaka: "Neutron activation crosssections of 12C, 27 AI, 59CO, natcu and 209Bi nuclides
in the energy range of 20 MeV to 200 MeV", Int.
Conf. on Nuclear Data for Science and Technology,(Nuclear Data Centre, ENEA ICTP), Trieste, Italy,
May (1997).
N. Nishimori, K. Sagara, T. Fujita, H. Akiyoshi, H.
Nakamura, and T. Nakashima: "Precise experimenton n+d scattering at 12 MeV", 15th Int. Conf. on
Few-Body Problems in Physics, (KVI), Groningen,
The Netherlands, July (1997).
T. Kohno, 1. Yamagiwa, H. Miyasaka, T. Goka, and
H. Matsumoto: "Observation of heavy ions withADEOS satellite", 25th Int. Cosmic Ray Conf., (International Union of Pure and Applied Physics),
Durban, South Africa, July (1997).
T. Takashima, T. Doke, T. Hayashi, J. Kikuchi, K.
Itsumi, M. Kobayashi, H. Shirai, N. Takehana, N.
Hasebe, K. Kondoh, T. Kohno, K. Munakata, C.
Kato, S. Yanagita, Y. Yamada, D. Reames, and T.
von Rosenvinge: "The first observation of sulfur inanomalous cosmic rays by the GEOTAIL and the
WIND spacecrafts", 25th Int. Cosmic Ray Conf.,(International Union of Pure and Applied Physics),
Durban, South Africa, July (1997).
G. 1. Pugacheva, A. A. Gusev, T. Kohno, 1. M.
Martin, W. Spjeldvik, and T. Almand: "The 1-9
MeV Inucleon He flux dynamics in the inner magnetosphere during 1984-1986", 25th Int. Cosmic Ray
Conf., (International Union of Pure and Applied
Physics), Durban, South Africa, July (1997).
Y. Muraki, K. Masuda, Y. Matsubara, T. Sako,
1. Imaida, H. Tsuchiya, T. Kohno, T. Goka, H.
Matsumoto, T. Omoto, Y. Fujiwara, K. Taguchi, M.
Nakazawa, 1. Tanaka, M. Fujii, and H. Ikeda: "Scintillation fiber telescope for detecting neutrons in asatellite experiment", 25th Int. Cosmic Ray Conf.,(International Union of Pure and Applied Physics),
Durban, South Africa, July (1997).
T. Uesaka, H. Okamura, T. Ohnishi, Y. Satou, S.
Ishida, N. Sakamoto, H. Otsu, T. Wakasa, T.
Nonaka, G. Yokoyama, K. Sekiguchi , K. Ito, T.
266

Wakui, M. Wakasugi, Y. Yano, S. Haruyama, T.
Ikeda, and H. Sakai: "Measurement of polarization
correlation coefficient for the 3He( d~ p )4He reaction" ,4th Int. Symp. Deuteron '97, (Joint Institute for Nuclear Research), Dubna, Russia, July (1997).
K. Sugawara-Tanabe and K. Tanabe: "Doubly periodic motion in superdeformed states and ~I = 2
staggering", Int. Symp. on Symmetries in Science X,(Technische Univ. Clausthal and Technische Univ.
Graz), Bregenz, Austria, July (1997).
K. Yoneda, N. Aoi, H. Iwasaki, H. Sakurai, H. Ogawa,T. Nakamura, W.-D. Schmidt-Ott, M. Shaefer, M.
Notani, N. Fukuda, E. Ideguchi, T. Kishida, S. S.
Yamamoto, and M. Ishihara: "Measurement of halflives and delayed neutron emission probabilities oflight nuclei near the drip line (Z = 5~7)", 1997 Fall
Meet. of Physical Society of Japan, Hachioji, Sept.
(1997).
K. Sugawara-Tanabe, N. Yoshida, and A. Arima: "Deformation effect on the pairing interaction", 1997
Fall Meet. of Physical Society of Japan, Hachioji,
Sept. (1997).
T. Horibata, M. Oi, and N. Onishi: "Constrained
GCM Calculation based on 3D-CHFB", 1997 Fall
Meet. of Physical Society of Japan, Hachioji, Sept.
(1997).
T. Horibata, M. Oi, and N. Onishi: "GCM calculationin which the expectation values of angular momentum and particle number are conserved", 1997 Fall
Meet. of Physical Society of Japan, Hachioji, Sept.
(1997).
M. Oi, N. Onishi, N. Tajima, and T. Horibata: "Tilted
axis rotating states of Osmium182", 1997 Fall Meet.
of Physical Society of Japan, Hachioji, Sept. (1997).
J. Meng, K. Sugawara-Tanabe, S. Yamaji, P. Ring,
and A. Arima: "Pseudo-spin symmetry in realistic
nuclei", 1997 Fall Meet. of Physical Society of Japan,
Hachioji, Sept. (1997).
S. Ishida, Y. Satou, H. Sakai, H. Okamura, H. Otsu,
N. Sakamoto, T. Uesaka, T. Wakasa, T. Ohnishi,
T. Nonaka, G. Yokoyama, T. Niizeki, T. Ichihara,
K. Hatanaka, and N. Nishimori: "Measurement of
the spin transfer observables via the 12C( d,d') reaction", 1997 Fall Meet. of Physical Society of Japan,
Hachioji, Sept. (1997).
N. Kawamura, K. Nagamine, T. Matsuzaki, K. Ishida,
S. N. Nakamura, S. Sakamoto, M. Tanase, M. Kato,
K. Kurosawa, K. Kudoh, N. Takeda, and G. H.
Eaton: "M uon catalyzed fusion experiment for DT system at RIKEN-RAL Muon Facility (6) Fusion
neutron measurement", 1997 Fall Meet. of PhysicalSociety of Japan, Hachioji, Sept. (1997).
K. Ishida, K. Nagamine, T. Matsuzaki, S. N.
Nakamura, N. Kawamura, S. Sakamoto, M. Tanase,
M. Kato, K. Kurosawa, K. Kudoh, N. Takeda, andG. H. Eaton: "Muon catalyzed fusion experiment forDT system at RIKEN-RAL Muon Facility (7) Alpha sticking X-ray measurement", 1997 Fall Meet.

of Physical Society of Japan, Hachioji, Sept. (1997).
K. Sumiyoshi, S. Yamada, H. Suzuki, and W .
Hillebrandt: "Explosion of neutron star with minimum mass and r-process", 1997 Fall Meet. of Physical Society of Japan, Hachioji, Sept. (1997).
H. Kurasawa and T. Suzuki: "Double giant resonancestates", Tours Symp. on Nuclear Physics III, (University of Tours), Tours, France, Sept. (1997).
T. Horibata, M. Oi, and N. Onishi: "Constraint GCM+ 3-dimensional cranked HFB" , 3rd Workshop for
Physics of RI Beam Factory: Mean Field in Unstable
Nuclei, Wako, Nov. (1997).
K. Sumiyoshi: "Mean-field frameworks for astrophysics" , 3rd Workshop for Physics of RI Beam Factory: Mean Field in Unstable Nuclei, Wako, Nov.
(1997).
T. Nakamura: "Radioactive ion beam research at
RIKEN", Int. Conf. on Fission and Properties of
Neutron-rich Nuclei, (Vanderbilt University), Sanibel Island, U.S.A., Nov. (1997).
K. Sumiyoshi, B. Carlson, 1. Tanihata, Y Sugahara, S.
Sugimoto, H. Toki, and D. Hirata: "Ground state
properties of unstable nuclei in the relativistic mean
field framework", Int. Symp. on Innovative Computational Methods in Nuclear Many-Body Problems,(RCNP, Osaka Univ.), Osaka, Nov. (1997).
H. Kurasawa and T . Suzuki: "Spin dipole states ofdeformed nuclei", Int. Symp. on New Facet of Spin
Giant Resonances in Nuclei, (Univ. Tokyo), Tokyo,
Nov. (1997).
S. Ishida, Y. Satou, H. Sakai, H. Okamura, H. Otsu,
N. Sakamoto, T. Uesaka, T. Wakasa, T. Ohnishi,
T. Nonaka, G. Yokoyama, T. Niizeki, T. Ichihara,
K. Hatanaka, and N. Nishimori: "Study of isoscalarspin strength via the 12C(d~ cp) reaction", Int. Symp.
on New Facet of Spin Giant Resonances in Nuclei,(Univ. Tokyo), Tokyo, Nov. (1997).
Y. Mizoi, T. Fukuda, Y. Matsuyama, T. Miyachi,
H. Miyatake, N. Aoi, N. Fukuda, M. Notani, Y.
Watanabe, K. Yoneda, H. Sakurai, Y. Watanabe,
A. Yoshida, and M. Ishihara: "Measurement ofcross sections of the BLi(o:,n)l1B reaction and theBLi( o:,o:n)1Li reaction with the new MUSIC detector", Int. Symp. on Origin of Matter and Evolutionof Galaxies '97, (CNS, Univ. Tokyo), Atami, Nov.
(1997) .
K. Sumiyoshi, S. Yamada, H. Suzuki, and W.
Hillebrandt: "Explosion of a neutron star just below the minimum mass", Int. Symp. on Origin of
Matter and Evolution of Galaxies '97, (CNS, Univ.
Tokyo), Atami, Nov. (1997).
K. Sumiyoshi, H. Suzuki, S. Yamada, and W.
Hillebrandt: "The fate of a neutron star just below the minimum mass" , Neutron Stars and Pulsars:
Thirty Years after the Discovery, (Rikkyo U niv. ) ,Tokyo, Nov. (1997).

3.

Atomic and solid-state physics

T. Kambara:"Three dimensional recoil-ion momentum spectroscopy for atomic collision studies",
RIKEN Symp. on Studies on Condensed Matter
Physics, Atomic Physics, Nuclear Chemistry, andBiology and Medicine Using RIKEN Acccelerators,
Wako, Feb. (1997).
N. Ishikawa, Y. Chimi, A. Iwase, K. Tsuru, O.
Michikami, T. Kambara, T. Mitamura, Y. Awaya,
and M. Terasawa: "Velocity effects on defect production in ion-irradiated high-Tc superconductors" ,52nd Ann. Meet. of Physical Society of Japan,
Nagoya, Mar. (1997).
D. Chiba, T. Takayanagi, K. Wakiya, Y. Kanai, T.
Kambara, and Y. Awaya: "Measurement of angular
distribution for emitted electrons with toroidal spectrometer (II)", 52nd Ann. Meet. of Physical Societyof Japan, Nagoya, Mar. (1997).
M. Kokubu, E. Idesawa, T. Kamae, A. Kubota, Y.
Saito, M. Tashiro, Y. Fukazawa, K. Makishima, K.
Matsuzaki, T. Mizuno, J. Kataoka, T. Takahashi,
K. Takizawa, A. Yoshida, and HXD Team: "An activation testing of GSO, BGO scintillators for cosmic
hard X-ray detectors" , 52nd Ann. Meet. of PhysicalSociety of Japan, Nagoya, Mar. (1997).
E. Vagi: "Application of accelerators in materials researches", Center for Advanced Research of Energy
Technology Symp., Hokkaido University, Sapporo,
Mar. (1997).
E. Vagi: "Materials researches with accelerators",
Hasiguti Memorial Symp., Tokyo, Mar. (1997).
E. Vagi: "Solid krypton formation in aluminium andstate of hydrogen dissolved in metals investigated by
the channelling method", 1st TESLA Workshop on
Modification of Materials by Ion Beams, (TESLA
Scientific Center), Beograd, Yugoslavia, Apr. (1997).
E. Vagi: "Formation of heavy inert gas bubbles in metals" , 13th Int. Conf. on Ion Beam Analysis (IBA-13),
Lisbon, Portugal, July (1997).
A. Igarashi and I. Shimamura: "S-wave resonances in
e+ + He+ scattering", 22nd Ann. Meet. of Society
for Atomic Collision Research, Kyoto, Aug. (1997).
T. Ichioka, Y. Yamazaki, K. Komaki, T. Azuma, andK. Kuroki: "Atomic physics with ultra slow antiprotons", 22nd Ann. Meet. of Society for Atomic Collision Research, Kyoto, Aug. (1997).
M. Kitajima, Y. Nakai, Y. Kanai, Y. Yamazaki, Y.
Awaya, and Y. Itoh: "Present status of the low energy multi-charged ion-atom collision experiment using the RIKEN ECRIS", 22nd Ann. Meet. of Society
for Atomic Collision Research, Kyoto, Aug. (1997).
S. Ninomiya, Y. Yamazaki, K. Komaki, T. Azuma,
H. Masuda, F. Koike, K. Kuroki, and M. Sekiguchi:"Interaction of slow highly charged ions with a microcapillary Ni foil" , 22nd Ann. Meet. of Society for
Atomic Collision Research, Kyoto, Aug. (1997).
T. Kambara, Y. Nakai, T. M. Kojima" Y. Awaya, I.

267

Shimamura, V. Mergel, H. Schmidt-Backing, B. D.
DePaola, and M. Kimura: "Differential cross section of single electron cupture in 10 MeV Ar 8 + +Hecollisions", 22nd Ann. Meet. of Society for Atomic
Collision Research, Kyoto, Aug. (1997).
T. Miyabe, H. Tsuchida, M. Imai, A. Itoh, N. Imanishi,
Y. Nakai, and T. Kambara: "Fragment Process of
C 60 by fast charged particles II", 22nd Ann. Meet. ofSociety for Atomic Collision Research, Kyoto, Aug.
(1997).
S. Koike, E. Yagi, and H. Kojima: "The terminal solubility curves of hydrogen in Nb-Mo (3 at%) alloys",
1997 Fall Meet. of Japan Institute of Metals, Sendai,
Sept. (1997).
T. Kambara: "Atomic physics at the planned new
RIKEN Facility", 3rd Euroconference on Atomic
Physics with Stored Highly Charged Ions, Ferrara,
Italy, Sept. (1997).
Y. Kobayashi, Y. Yoshida, K. Hayakawa, K. Yukihira,J. Nakamura, H. Haesslein, R. Sielemann, S. Nasu,
N. Inabe, Y. Watanabe, A. Yoshida, M. Kase, A.
Goto, Y. Yano, E. Yagi, and F. Ambe: "In-beam
Massbauer spectrometers for materials science at
RIKEN Accelerator Research Facility", Int. Conf.
on the Applications of the Massbauer Effect, Rio deJaneiro, Brazil, Sept. (1997).
Y. Yoshida, Y. Kobayashi, K. Hayakawa, K. Yukihira,J. Nakamura, E. Yagi, F. Ambe, and S. Nasu: "Jumpprocesses of 57Fe atoms in solid Ar and solid Xe",
1997 Fall Meet. of Physical Society of Japan, Kobe,
Oct. (1997).
A. Yamashita, K. Ishii, T. Yokoo, J. Akimitsu, M.
Hedo, Y. Inada, Y. Onuki, E. Yamamoto, Y. Haga,
and R. Kadono: "Anomalous field dependence ofmagnetic penetration depth in the vortex state of
CeRu2", 1997 Fall Meet. of Physical Society ofJapan, Kobe, Oct. (1997).
K. Ishii, S. Kawae, T. Nakano, K. Ando, H. Oyama,
and T. Kambara: "Rydberg transitions of highly
charged neon ion in beam-foil collision", 1997 Fall
Meet. of Physical Society of Japan, Kobe, Oct.
(1997).
K. Ando, T. Nakano, K. Ishii, S. Kawae, T. Kambara,and H. Oyama: "Rydberg transition of highly
charged krypton ion in beam-foil collision", 1997
Fall Meet. of Physical Society of Japan, Kobe, Oct.
(1997).
H. Tsuchida, T. Miyabe, M. Imai, A. Itoh, N.
Imanishi, Y. Nakai, and T. Kambara: "Study of C 60 mutifragmentation in heavy-ion collisions C: Masscorrelation", 1997 Fall Meet. of Physical Society ofJapan, Kobe, Oct. (1997).
S. Uramoto, H. Sato, and I. Shimamura: "Doubly excited states of the hydrogen molecule", 1997 Fall
Meet. of Physical Society of Japan, Kobe, Oct.
(1997).
N. Kuroda, N. Ishikawa, S. Okayasu, A. Iwase, H.
Ikeda, R. Yoshizaki, and T. Kambara: "Pinning in
268

Bi-based superconductors irradiated with 3.5 GeV
Xe ion", 1997 Fall Meet. of Physical Society of Japan,
Kobe, Oct. (1997).
H. Sakairi, E. Yagi, and A. Koyama: "Annealing of
CU3Au irradiated with protons, a-particles or C ionsat liquid nitrogen temperature", 8th Int. Conf. on
Fusion Reactor Materials, Sendai, Oct. (1997).
E. Yagi: "Formation of heavy inert gas bubbles in materials", 8th Int. Conf. on Fusion Reactor Materials,
Sendai, Oct. (1997).
I. Shimamura: "Physics of electron collision processes
manifest in their cross sections", 1997 Fall Meet. ofPhysical Society of Japan, Kobe, Nov. (1997).
T. Ichioka: "Production of slow antihydrogen beam",
14th RIKEN Symp. on Atomic Physics Using Accelerators, Wako, Dec. (1997).
Y. Yamazaki: "Interaction of ions with matter",
RIKEN Symp. on Materials Science in RIKEN RI
Beam Factory, Wako, Dec. (1997).
T. Nishimura: "Vibrationally elastic scattering of
positrons from methane molecules", Uchu-Kagaku
Kenkyuusyo Uchu Kuukan Genshi Bunshi Katei
Kenkyuukai, Sagamihara, Dec. (1997).
S. Uramoto, H. Sato, and I. Shimamura: "Superexcited states of the hydrogen molecule", Uchu-Kagaku
Kenkyuusyo Uchu Kuukan Genshi Bunshi Katei
Kenkyuukai, Sagamihara, Dec. (1997).

4.

Radiochemistry, radiation chemistry, and radiation biology

S. Enomoto: "Study on bio-trace elements by using themultitracer technique" , RIKEN Symp. on Studies on
Condensed Matter Physics, Atomic Physics, Nuclear
Chemistry, and Biology and Medicine Using RIKEN
Accelerators, Wako, Feb. (1997).
R. Hirunuma, N. Sotogaku, K. Endo, S. Enomoto, S.
Ambe, and F. Ambe: "Study of the uptake of traceelements in Se-deficient rats", 117th Ann. Meet.
of Pharmaceutical Society of Japan, Tokyo, Mar.
(1997).
S. Enomoto: "Dynamics of bio-trace elements by using the multitraces technique", 40th Ann. Symp.
of Japan Society of Plasma Spectroscopic Analysis,
Nagoya, Mar. (1997).
R. Hirunuma, N. Sotogaku, K. Endo, S. Enomoto, S.
Ambe, and F. Ambe: "The uptakes of various traceelements in Se deficient rats" , RIKEN Symp. on BioThace Elements '97, Wako, Mar. (1997).
N. Sotogaku, R. Hirunuma, K. Endo, S. Enomoto, S.
Ambe, and F. Ambe: "Study on binding of blood
serum and various trace elements", RIKEN Symp.
on Bio-Thace Elements '97, Wako, Mar. (1997).
S. Enomoto: "Dynamics of various trace elements inliver diseases", RIKEN Symp. on Bio-Thace Elements '97, Wako, Mar. (1997).
T. Ozaki, S. Enomoto, Y. Minai, S. Ambe, F. Ambe,and Y. Makide: "Influence of aluminum on the up-

take of various cations from a solution into carrots" ,4th Int. Conf. on Methods and Applications of Radioanalytical Chemistry, (American Nuclear Society), Hawaii, U.S.A., Apr. (1997).
T. Shinonaga, S. Ambe, and 1. Yamaguchi: "Uptake
rate of trace elements by soybean plant", 4th Int.
Conf. on Methods and Applications of Radioanalytical Chemistry, (American Nuclear Society), Hawaii,
U.S.A., Apr. (1997) .
T. Nozaki, Y. Itoh, Z. Peng, Y. Ito, N. Nakanishi,
H. Yoshida, and A. Goto: "Preparation of positronsource for slow positron beam by ion bombardment on liquid and gas targets", 11th Int. Conf. on
Positron Annihilation (ICPA-11), Kansas, U.S.A.,
May (1997).
R. Hirunuma, S. Enomoto, S. Ambe, F. Ambe, N.
Sotogaku, and K. Endo: "Study of the uptake oftrace elements in Se-deficient rats using the multitracer technique", 8th Ann. Meet. of Japan Society
for Biomedical Research on Trace Elements, Tokyo,
July (1997).
N. Sotogaku, K. Endo, R. Hirunuma, S. Enomoto, S.
Ambe, and F. Ambe: "Binding properties of various
metals to blood components and serum proteins",
8th Ann. Meet. of Japan Society for Biomedical Research on Trace Elements, Tokyo, July (1997).
S. Enomoto, R. Hirunuma, S. Ambe, and F. Ambe:"Biobehavior of various trace elements in hepatopathy animals", 8th Ann. Meet. of Japan Society for
Biomedical Research on Trace Elements, Tokyo, July
(1997).
R. Hirunuma, N. Sotogaku, K. Endo, S. Enomoto, S.
Ambe, and F. Ambe: "Application of the multitracer technique: Metabolic study of trace elements
in selenium-deficient rats" ,8th Int. Conf. on Bioinorganic Chemistry, (Science Council of Japan, Chemical Society of Japan), Yokohama, July (1997).
N. Sotogaku, R. Hirunuma, K. Endo, S. Enomoto, S.
Ambe, and F. Ambe: "Studies of the binding of various trace elements to blood components and serum
proteins by means of the multitracer technique",8th Int. Conf. on Bioinorganic Chemistry, (Science
Council of Japan, Chemical Society of Japan), Yokohama, July (1997).
N. Hayakawa, S. Enomoto, R. Hirunuma, K. Endo, S.
Ambe, and F. Ambe: "Metabolic study of trace elements in liver cancer bearing rats" ,8th Int. Conf. on
Bioinorganic Chemistry, (Science Council of Japan,
Chemical Society of Japan), Yokohama, July (1997).
S. Enomoto, R. G. Weginwar, R. Hirunuma, S. Ambe,and F. Ambe: "Metabolic study of trace elements inacute alcoholic mice" ,8th Int. Conf. on Bioinorganic
Chemistry, (Science Council of Japan, Chemical Society of Japan), Yokohama, July (1997).
S. Enomoto, B. Liu, S. Ambe, and F. Ambe: "Accumulation of inorganic elements in ddY mice implantedwith Ehrlich sarcoma", 8th Int. Conf. on Bioinorganic Chemistry, (Science Council of Janan, Chemi-

cal Society of Japan), Yokohama, July (1997).
T. Abe, C. H. Bae, T. Matsuyama, and S. Yoshida:"Hormone mutants obtained by heaby-ion beam irradiation", Plant Biology '97, (American Societyof Plant Physiologists), Vancouver, Canada, Aug.
(1997).
F. Ambe and S. Enomoto: "The multitracer techniquein bio-trace element research", RIKEN Int. Symp.
on Bio-Trace Elements '97 (BITREL '97), Hachioji,Aug. (1997).
R. Hirunuma, N. Sotogaku, K. Endo, S. Enomoto, S.
Ambe, and F. Ambe: "Comparison of behavior oftrace elements between selenium-deficient and normal rats using the multitracer technique", RIKEN
Int. Symp. on Bio-Trace Elements '97 (BITREL '97),
Hachioji, Aug. (1997).
J. Chou, S. Enomoto, S. Ambe, and F. Ambe: "Multitracer study on binding activity of various traceelements to metallothionein", RIKEN Int. Symp.
on Bio-Trace Elements '97 (BITREL '97), Hachioji,Aug. (1997).
R. G. Weginwar, M. Katayama, S. Enomoto, S. Ambe,T. Ozaki, and F. Ambe: "Metabolism of trace elements in marine euglena: A study using the multitracer", RIKEN Int. Symp. on Bio-Trace Elements'97 (BITREL '97), Hachioji, Aug. (1997).
T. Ozaki, S. Enomoto, Y. Minai, S. Ambe, and F.
Ambe: "Influence of aluminium on the uptake ofvarious cations from a solution into carrots" , RIKEN
Int. Symp. on Bio-Trace Elements '97 (BITREL '97),
Hachioji, Aug. (1997).
R. Amano, S. Oishi, S. Enomoto, and F. Ambe: "Simultaneous tracing of 14 elements in mice and rats
using the radioactive multitracer technique" , RIKEN
Int. Symp. on Bio-Trace Elements '97 (BITREL '97),
Hachioji, Aug. (1997).
N. Sotogaku, .K. Matsumoto, K. Endo, R. Hirunuma,
S. Enomoto, S. Ambe, and F. Ambe: "Metal binding properties of various trace elements to serum
proteins by means of the multitracer technique",
RIKEN Int. Symp. on Bio-Trace Elements '97 (BITREL '97), Hachioji, Aug. (1997).
S. Enomoto: "Trends in bio-trace elements research on
ICBIC8 and BITREL'97", 16th Symp. of Bio Trace
Elements Research, Gifu, Aug. (1997).
F. Yatagai, Y. Kagawa, N. Fukunishi, N. Inabe, T.
Shimazu, M. Hirano, K. Eguchi-Kasai, Y. Furusawa,
K. Tatsumi, M. Watanabe, T. Kato, and F. Hanaoka:"Analysis of mutations in the human HPRT gene induced by heavy-ion irradiation", 7th Int. Conf. on
Environmental Mutagens, Toulouse, France, Sept.
(1997).
F. Yatagai, Y. Kagawa, N. Fukunishi, N. Inabe, T.
Shimazu, S. Kanai, M. Hirano, M. Suzuki, K.
Eguchi-Kasai, Y. Furusawa, K. Tatsumi, M. Watanabe, T. Kato, and F. Hanaoka: "Analysis of mutations in the human HPRT gene induced by heavy-ion
irradiation", 6th Workshop on Heavy-Charged Par269

tides in Biology and Medicine, (GSI), Baveno, Italy,
Sept. (1997).
C. H. Bae, T. Abe, T. Matsuyama, T. Nakano, andS. Yoshida: "Effect of heavy-ion beam irradiation on
mutation induction in plants at pollination stage II" ,92nd Meet. of Japanese Society of Breeding, Tottori,
Oct. (1997).
T. Nozaki, Y. Itoh, Z. Peng, Y. Ito, N. Nakanishi, H.
Yoshida, and A. Goto: "Preparation of 18F source forslow positron beam by proton bombardment of 18 0_
water", Asia-Pacific Symp. on Radiochemistry '97,
(Kumamoto University), Kumamoto, Oct. (1997).
S. Ambe, T. Ozaki, R. G. Weginwar, S. Enomoto, and
F. Ambe: "Production of carrier-free multitracers
containing Mg-28 and Ca-47 by high-energy heavyion irradation", Asia-Pacific Symp. on Radiochemistry '97, (Kumamoto University), Kumamoto, Oct.
(1997).
R. Hirunuma, N. Sotogaku, K. Endo, S. Enomoto,
S. Ambe, and F. Ambe: "Application of the multiracer technique: Time dependence of distributionof trace elements in Se-deficient rats", Asia-PacificSymp. on Radiochemistry '97, (Kumamoto University), Kumamoto, Oct. (1997).
S. Enomoto, R. Hirunuma, S. Ambe, and F. Ambe:"Dynamics of trace elements in liver disease rat andmice", Asia-Pacific Symp. on Radiochemistry '97,
(Kumamoto University), Kumamoto, Oct. (1997).
J. Chou, S. Enomoto, S. Ambe, and F. Ambe: "Multitracer study on coordinating of the rare-earth element with metallothionein", Asia-Pacific Symp. on
Radiochemistry '97, (Kumamoto University), Kumamoto, Oct. (1997).
S. Oishi, R. Amano, A. Ando, S. Enomoto, and F.
Ambe: "Simultaneous biobehavior of Sc, Mn, Fe,
Co, Zn, Se, Rb, and Zr trace elements in C57BL/6N
mice", Asia-Pacific Symp. on Radiochemistry '97,
(Kumamoto University), Kumamoto, Oct. (1997).
R. G. Weginwar, M. Katayama, S. Ambe, S. Enomoto,T. Ozaki, and F. Ambe: "Metabolism of trace elements in marine Euglena: A study using the multitracer", Asia-Pacific Symp. on Radiochemistry '97,
(Kumamoto University), Kumamoto, Oct. (1997).
H. Wang, S. Ambe, N. Takematsu, and F. Ambe:"Model study of influence of acid rain on adsorptive
behavior of trace elements on soil by the multitracer
technique", Int. Congr. of Acid Snow and Rain 1997,(Research Association of Acid Snow and Rain), Niigata, Oct. (1997).
T. Shinonaga, S. Ambe, and 1. Yamaguchi: "Uptake and translocation of Sr, Tc, and Cs in soybean
plants", Int. Meet. on Influence of Climatic Characteristics upon Behavior of Radioactive Elements, (Institute for Environmental Sciences), Rokkashomura,
Oct. (1997).
S. Ambe, T. Shinonaga, T. Ozaki, S. Enomoto, H.
Yasuda, and S. Uchida: "Multitracer study on uptake of elements by komatsuna", Int. Meet. on In270

fluence of Climatic Characteristics upon Behavior ofRadioactive Elements, (Institute for Environmental
Sciences), Rokkashomura, Oct. (1997).
N. Shigematsu, T. Kawada, R. Ishibashi, T.
Nakayama, A. Takeda, A. Kubo, and H. Ito: "Analysis of mutation induction by X-rays and heavy ion
beams", Meet. of Japanese Society for Therapeutic
Radiology and Oncology, Kagawa, Oct. (1997).
K. Inoue, M. Kitoh, T. Oka, A. Samura, and Y. Hama:"The study of change of chemical structure and surface topology in polyethylenes irradiated by C and
Ar ion-beams under air and vacuum", 40th Symp.
on Radiation Chemistry, Tokaimura, Oct. (1997).
M. Miki, Y. Mizutani, K. Okamoto, Y. Izumi, Y.
Furusawa, K. Ushida, Y. Yoshida, and S. Tagawa:"Study on the behavior of geminate ion pair in alkane
by using picosecond pulse radiolysis" , 40th Symp. on
Radiation Chemistry, (Radiation Chemical Societyof Japan), Tokaimura, Oct. (1997).
N. Sotogaku, K. Endo, R. Hirunuma, S. Enomoto,
S. Ambe, and F. Ambe: "Biochemical studies ofblood components and transport protein with various trace elements", 41st Symp. on Radiochemistry,(Kumamoto University), Kumamoto, Oct. (1997).
H. Araki, J. Sanada, S. Morimoto, A. Yokoyama,
T. Saito, H. Baba, Y. Ohkubo, and Y. Kobayashi:"Heavy-ion induced fission in the medium energy
region", 41st Symp. on Radiochemistry and AsiaPacific Symp. on Radiochemistry '97, (Kumamoto
University), Kumamoto, Oct. (1997).
Y. Furusawa, M. Saitou , T. Kanai, and F. Yatagai:"REB and OER for a lethal effect of super highLET· 56 Fe and 40 Ar ion beam on V79 cell", 40th Ann.
Meet. of Japan Radiation Research Society, Kyoto,
Nov. (1997).
H. Sasaki, M. Parinaz, F. Yatagai, Y. Furusawa, and
F. Hanaoka: "Mechanisms of interphase-death induction for CHO cells exposed to accelerated heavyions" ,40th Ann. Meet. of Japan Radiation ResearchSociety, Kyoto, Nov. (1997).
F. Yatagai, Y. Kagawa, M. Hirano, N. Fukunishi, N.
Inabe, S. Kanai, T. Shimazu, K. Eguchi-Kasai, Y.
Furusawa, M. Suzuki, M. Watanabe, T. Kato, K.
Tatsumi, and F. Hanaoka: "Analysis of mutations in
the human HPRT gene induced by high LET heavyion irradiation", 40th Ann. Meet. of Japan Radiation
Research Society, Kyoto, Nov. (1997).
Y. Itoh, T. Nozaki, A. Goto, N. Nakanishi, Y. Ito, andH. Yoshida: "Development of spin polarized positronbeam", Tohoku Daigaku Kinzoku Kenkyusho Kyodoriyo Kenkyukai Yodenshi niyoru Zairyo Nano Kozokaiseki, Sendai, Nov. (1997).
F. Yatagai, Y. Kagawa, M. Hirano, N. Fukunishi, N.
Inabe, S. Kanai, K. Eguchi-Kasai, Y. Furusawa, M.
Suzuki, M. Watanabe, T. Kato, K. Tatsumi, and
F. Hanaoka: "Analysis of mutation in the human
HPRT gene induced by high-let heavy-ion", 26th
Ann. Meet. of Japan Environmental Mutagen Re-

search Society, Kanagawa, Dec. (1997).
M. Yoshimasu, T. Abe, S. Yoshida, T . Inoue, F. Ling,
and T. Shibata: "Using heavy-ion beam for isolationof yeast mitochondrial DNA ricombination deficientmutants", 20th Ann. Meet. of Japanese Society of
Molecular Biology, Kyoto, Dec. (1997).
K. Inoue, M. Kitou, T. Oka, A. Samura, Y. Hama, andF. Yatagai: "The study of change of chemical structure in polyethylenes irradiated by C and Ar ionbeams under air and vacuum", Meet. on Dielectricand Electrical Insulating Materials of IEEJ, Tokyo,
Dec. (1997).
Y. Itoh, T. Nozaki, A. Goto, N. Nakanishi, Y. Ito, andH. Yoshida: "The development of positron source
for spin polarized positron beam" , PF Slow-Positron
Facility Workshop, (KEK), Tsukuba, Dec. (1997).
S. Ambe: "Influence of acid rain and organic matterson the adsorption of trace elements on soil", Symp.
on the Behavior of Trace Substances in the Environment, (Kyoto Univ.), Kumatori, Dec. (1997).

5.

Material analysis

W. Hong, S. Hayakawa, K. Maeda, S. Fukuda, M.
Yanokura, M. Aratani, K. Kimura, Y. Gohshi, and
I. Tanihata: "Measurements of mass resolution anddepth resolution of TOF-ERDA on a Si wafer", 44th
Spring Meet. of Japan Society of Applied Physics
Related Society, (Nihon Univ.), Tokyo, Mar. (1997).
W. Hong, S. Hayakawa, K. Maeda, S. Fukuda, M.
Yanokura, M. Aratani, K. Kimura, Y. Gohshi, and
I. Tanihata: "Development of a high mass-resolution
TOF-ERDA system for a wide mass range from hydrogen to middle heavy elements", Asianalysis IV,(Kyushu Univ.), Fukuoka, May (1997).
Y. Itoh, H. Murakami, H. Takeno, S. Ushio, and T.
Takenaka: "Positron lifetime in flouting-zone grownsilicon wafer" ,11th Int. Conf. on Positron Annihilation (ICPA-11), Kansas City, U.S.A., May (1997).
W. Hong, S. Hayakawa, K. Maeda, S. Fukuda, M.

Yanokura, M. Aratani, K. Kimura, Y. Gohshi,
and I. Tanihata: "Light-element measurements ina metallic material using heavy-ion TOF-ERDA",
13th Conf. of Ion Beam Analysis, (Instituto Tecnologico e Nuclear), Lisbon, Portugal, July (1997).
K. Maeda, K. Hasegawa, H. Hamanaka, and M.
Maeda: "Chemical state analysis in atmospheric air
by high resolution PIXE" , 13th Int. Conf. on Ion
Beam Analysis, (Instituto Tecnologico e Nuclear),
Lisbon, Portugal, July (1997).
H. Murakami, Y. Itoh, and A. Kinoshita: "Surfaceof porous silicon studied by positron annihilation
spectroscopy-lifetime, doppler broadning and agemomentum correlation", Silicon Heterostructures:
From Physics to Devices, (Conference Chain Thomas
Pearsall, Univ. Washington), Tuscany, italy, Sept.
(1997).
K. Hasegawa, S. Nakayama, H. Hamanaka, and K.
Maeda: "Crystal spectrometer PIXE system using multi-anode PSPC" , 15th PIXE Symp. Japan,
Takasaki, Nov. (1997).
H. Yoshiki, K. Maeda, T. T. Inamura, A. Tonomura,and T. Tsuruda: "Trace element analysis of feathers" , 15th PIXE Symp. Japan, Takasaki, Nov.
(1997).
H. Murakami, N. Onizuka, J. Sasaki, and Y. Itoh:"Positron annihilation in amorphous fine powder", Tohoku Daigaku Kinzoku Kenkyusho Kyodoriyo Kenkyukai Yo dens hi niyoru Zairyo N ano Kozokaiseki, Sendai, Nov. (1997).
H. Murakami and Y. Itoh:"Positronium agemomentum corration for material charactarization", PF Slow-Positron Facility Workshop, (KEK),
Tsukuba, Dec. (1997).
H. Hamanaka, A. Tonomura, N. Izukura, K. Hasegawa,
K. Maeda, and S. Yumoto: "Chemical state analysis of Al compounds crystal spectrometer PIXE",
16th Symp. on Materials Science and Engineering
Research Center of Ion Beam Technology, Housei
University, Koganei, Dec. (1997).

271

x. LIST OF SYMPOSIA(J an.-Dec. 1997)
1) Symp. on Giant Resonances
27-28 Jan., Wako, RIKEN, Cyclotron Lab.
2) Symp. on Studies on Condensed Matter Physics, Atomic Physics, Nuclear Chemistry,
and Biology and Medicine Using RIKEN Accelerators
14 Feb., Wako, RIKEN, Atomic Physics Lab.
3) Symp. on Accelerator Techniques in RI Beam Factory Project19 Mar., Wako, RIKEN, Cyclotron Lab.
4) RIKEN Symp. on Bio-Trace Elements '97
25 Mar., Wako, RIKEN, Nuclear Chemistry Lab.
5) Symp. on RI Beam Factory and Astrophysics
24-25 Apr., Wako, RIKEN, Computational Science Lab. and Linear Accelerator Lab.
6) Workshop on Open Standards for Cascade Models at RHIC
23-27 June, New York, BNL, Radiation Lab.
7) Workshop on Perturbative QCD as a Probe of Hadron Structure
14-25 July, New York, BNL, Radiation Lab.
8) Workshop on Nuclear Reactions in Unstable Nuclei
17- 18 July, Wako, RIKEN, Linear Accelerator Lab.
9) Workshop on Hadron Helicity-Flip at RHIC Energies
21 July-30 Aug., New York, BNL, Radiation Lab.
10) RIKEN Int. Symp. on Bio-Trace Elements '97 (BITREL'97)
2-4 Aug., Hachioji, RIKEN, Nuclear Chemistry Lab.
11) Workshop on Cluster Physics in Unstable Nuclei
5-6 Aug., Wako, RIKEN, Linear Accelerator Lab.
12) Workshop on Non-Equilibrium Many Body Physics
23-25 Sept., New York, BNL, Radiation Lab.
13) 3rd INFN-RIKEN Meet. on Perspectives in Heavy Ions Physics
13-15 Oct., Padova, Univ. of Padova & LNL, Radiation Lab.
14) Informal Meet. on the Nuclear Equation of State
23 Nov., Wako, RIKEN, Linear Accelerator Lab.
15) Workshop on Mean Field in Unstable Nuclei
25- 26 Nov., Wako, RIKEN, Linear Accelerator Lab.
16) Symp. on Quarks and Gluons in Nucleon
28-29 Nov., Wako, RIKEN, Radiation Lab.
17) 14th Symp. on Atomic Physics Using Accelerators
16 Dec., Wako, RIKEN, Atomic Physics Lab.
18) RIKEN Symp. on Materials Science in RIKEN RI Beam Factory
22-23 Dec., Wako, RIKEN, Nuclear Chemistry Lab.
272

XI. LIST OF SEMINARS(Jan.-Dec. 1997)

Radiation Lab., Cyclotron Lab., andLinear Accelerator Lab.
1) G. P. Berg, Indiana Univ. (U.S.A.), 14 Jan.
"Experiments at 0 degree and accelerator projects
at IUCF"
2) W. Benenson, Michigan State Univ. (U.S.A.), 16Jan.
"NSCL upgrade project"
3) N. Christ, Columbia Univ. (U.S.A.), 29 Jan.
"The QCDSP project and computational quantum field theory""Elastic scattering of 11 Li"
13) S. Kuyucak, Australian National Univ. (Australia), 12 May"Vibron model: An algebraic approach to molecular spectroscopy"14) W. T. H. van Oers, University of Manitoba(Canada), 16 May"Studies of fundamental symmetries in nuclear reactions"
15) L. Va. Glozmann, Univ. of Graz (Austria), 26
May"Baryons and chiral symmetry in QeD"

4) J. Meng,

Technische Universitat Miinchen/RIKEN (Germany/Saitama), 10 Feb.
"Halo and giant halo for nuclei near the drip-line"5) V. G. Soloviev, Joint Inst. for Nuclear Research(Dubna), 13 Feb.
"On vibrational excitations in nuclei"
6) T. Marumori, Tsukuba Univ. (Ibaraki), 13 Feb.
"On band termination of nuclear collective rotation"16) D. Bucurescu, Institute of Atomic Physics (Rumania), 27 May"Spectroscopy of the N = Z nuclei 52Fe and
8 4 Mo"17) K. Sumiyoshi, Computational Science lab.,
RIKEN (Saitama), 2 June
"Explosion of a neutron star just below the minimum mass: A possible site for r-process"18) 1. T. Cheon, Yonsei Univ. (South Korea), 4 July7) K. Amos, Univ. Melbourne (Australia), 17 Mar.
"Fully microscopic model analysis of protonnucleus scattering: Elastic and discrete state inelastic events"
8) N. Cindro, Ruder Boskovic Institute (Zagreb), 17

Mar.
"The Hanbury-Brown/Twiss effects in nuclear
and subnuclear physics: Measuring nuclear dimensions by astrophysical method"9) G. C. Hillhouse, Stellenbosch Univ. (South
Africa), 1 Apr.
"Nuclear medium effects via quasielastic (p,P')and (f,fi) scattering"10) A. Gelberg, Univ. Kaln (Germany), 11 Apr.
"The interacting boson model and mixed symmetry status in the A = 130 mass region"
11) Y. Utsuno, Univ. Tokyo (Tokyo), 21 Apr.
"Nuclear structure of A rv 80 calculated by quantum Monte CaIro diagonalization method"12) C. Samanta, Saha Institute of Nuclear Physics(India), 6 May"Induced pseudoscalar coupling constant"19) A. B. Kurepin, Institute for Nuclear Research,
Russian Academy of Science (Russia), 17 July
"N arrow nuclear resonance of high excitation energies"

20) W. Q. Shen, Shanghai Institute of Nuclear Research (China), 8 Aug.
"Azimuthal distribution and azimuthal correlation and Smolukuski calculation about fission delay for 10.6 MeV /u 84Kr +27 AI"21) H. Wollnik, Univ. Giessen (Germany), 12 Aug.
"Mass measurements of exotic nuclei at ESR of
the GSI"
22) S. Nakamura, Muon Science Lab., RIKEN(Saitama), 26 Sept.
"A new data acquisition system for RIKEN-RAL
J.L-CF experiment"
23) B. Gruber, Southern Illinois University (U.S.A.),
29 Oct.

"Algebraic shells and the interacting boson modelof the nucleus"27324) J. Lattimer, State Univ. of New York, Stony
Brook (U.S.A.), 21 Nov.
"Observational constraints of the equation ofstate: Recent developments"
25) P. Descouvemont, Free University of Bruxelles(Belgium), 25 Nov.
"Light nuclear systems in a microscopic cluster
description"26) E. Sthephenson, Indiana Univ. Cyclotron Facility(U.S.A.), 27 Nov.
"Physics with the IUCF K600 spectrometer"27) 1. Katayama, Univ. Tokyo (Tokyo), 4 Dec.
"Proposals of a new cyclotron ion guide"28) M. Sambataro, Catania section of the National
Institute of Nuclear Physics (Italy), 9 Dec.
"Boson and fermion mappings of fermion systems"3) T. M. Kojima, ISAS (Saitama), 26 June
"4d Photoionization of lanthanide ions"4) M. Inokuti, Argonne National Laboratory(U.S.A.), 14 Nov.
"Review of scientific research programs and organizations"5) S. Uramoto, ISAS (Saitama), 20 Nov.
"Superexcited states of the hydrogen molecule"

RI Beam Factory1) Y. Lin, Tsinghua Univ. (China), 18 Feb.
"Electron linear accelerators' R&D at Tsinghua
University"
2) J. Vamos, Institute of Nuclear Research ATOMIKI (Hungary), 8 Apr.
"Status of the new Hungarian 14.5 GHz ECR ion
source"29) Ian. S. Towner, Queen's University (Canada), 12
Dec.
"Isospin-symmetry breaking in Fermi beta decay
and the determination of V ud"3) 1. Miura, RCNP (Japan), 21 Apr.
"AVF Cyclotron and Ring Cyclotron in RCNP"

Atomic Physics Lab.

4) T. T. Inamura, RIKEN (Japan), 23 Apr.
"SPECTROSCOPY by Hantaro NAGAOKA: Pioneer Nuclear-Stucture Study made at RIKEN"

1) T. Kambara, IS AS (Sagamihara), 17 Apr.
"Atomic collisions studied by recoil ion momentum analyses"
2) K. Yoshino, Harvard-Smithsonian Center for Astrophysics (U.S.A.), 17 Apr.
"The combination of a VUV Fourier-transform
spectrometer and synchrotron radiation for molecular absorption"

2745) A. Bandyopadhay, VECC (India), 23 June
"Design of Variable-frequency IH-Linac for CSM"
6) S. Biri (Institute of Nuclear Research/Hungary),
14 Nov.
"Recent Improvements on the ATOMKI 14.5 andon the RIKEN 18 GHz ECRIS"XII. LIST OF PERSONNEL'* *RIKEN Accelerator Research Facility
ISHIHARA Masayasu 15
iE(Facility Director)
AMBE Fumitoshi $:: g.~ )( fit (Vice Facility Director)
YANO Yasushige
lff $:: I(Vice Facility Director)*-

Linac Division
CHIBA Toshiya~ ;f1J ~IKEZAWA Eiji rtf! rR ?If
KOHARA Shigeo IJ,
I ::kHEMMI Masatake ~ J! i&
KASE Masayuki 110 ~ ~ Z
MIYAZAWA Yoshitoshi g ¥R {* fit*1

Ring Cyclotron Division
FUJITA Jiro ~ H3~~
IKEGAMI Kumio rtf!LjL=~
KAGEYAMA Tadashi ~ LlJ IE
KASE Masayuki 110 11{ ~ Z
KUBO Toshiyuki ~ {;~ fit ¥NAKAGAWA Takahide q:t Jil :2f. ~OKUNO Hiroki ~ If It tit
YOKOYAMA Ichiro ;fl LIJ - ~~GOTO Akira 1~ ~ ~*1
INABE Naohito fIB:ill ~ A
KAMIGAITO Osamu L:m;;'1~­
KOHARA Shigeo IJ,}Jj( I ~NAGASE Makoto
iIi [6l
OGIWARA Kiyoshi ~~~SAKAMOTO Naruhiko :!&JrZ ~Experimental Support Division
ICHIHARA Takashi m}Jj( ¥KANAI Yasuyuki i: jf
Z
KUMAGAI Hidekazu ~~;e. ~ fo
MORITA Kosuke ~ H3 i1!f 1r
YATAGAI Fumio ~H3Jl)(~

KAMBARA Tadashi t$
iE * 1
KOBAYASHI Toshio Ij,
ft 1$
MATSUZAKI Teiichiro t~Jh&jfjt-~~
WATANABE Yasushi ill jI

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m:

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Radioisotope Facilities Division
AMBE Fumitoshi $:: g:~ )( fit*1

KOBAYASHI Yoshio

Radiation Protection Group
FUJITA Shin ~ 83 fJT*1
NAKAJIMA Shunji q:t Jifb ~*ITO Sachiko -@t ~ ff r
UWAMINO Yoshitomo L

a ft H}j

Administration Division
NAKAMURA Toshiko q:t t-t L r
NUMATA Shigeo rB H3~

NISHIGUCHI Fumiyoshi

1!§' D ·X W*2

Steering Committee
AM BE Fumitoshi $:: g:~ X fit
GOTO Akira 1~ ~ ~ISHIHARA Masayasu 15
iE
KATSUMATA Koichi M1 X ffJL MATSUOKA Masaru t~ WiJ M1
MIYAZAWA Yoshitoshi '§ rR {* fit
NAKANISHI Noriyoshi q:t 1!§' if.2. %TAKAMI Michio ~ J! ~ ~YAGI Eiichi )\YANO Yasushige
lff $:: I
YOSHIDA Shigeo E H3~

AONO Masakazu W lff IE fD
HANAOKA Fumio 1E WiJ X 1$
KAMBARA Tadashi t$
iE
KOBAYASHI Toshio Ij,
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MATSUZAKI Teiichiro t~Jh&jf~-~~NAGAMINE Kanetada 71<. ~ ~ ,'it',
NISHI G U CHI Fumiyoshi 1!§' 0 )( #&TANIHATA Isao ;e. iHl ~ ~*3
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YATAGAI Fumio ;e.83JlX~

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ENOMOTO Shuichi II
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INABE Naohito *18 ill foj A
KIM Jong Won ~ ~ 5t*1
OHNISHI Jun-ichi[9 *if! SAKAMOTO Naruhiko j£
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IKEGAMI Kumio nE.1:-JL=~
KAMIGAITO Osamu 1:m)t1-f~ ­KUBO Toshiyuki ~ 1* fib. ¥OKUNO Hiroki ~ If Jt. flt
TAN ABE Toshiya IE ill fU!l. -m
YANO Yasushige ~ If 17: £*2*2 HeadCosmic Radiation Laboratory
KATO Hiroshi 110 Hi t-f
YOSHIDA Atsumasa ::g IE ~ lE

KOHNO Tsuyoshi

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GOKA Tateo Ii
HASEBE Nobuyuki ~~Jr~f~1-r (Fac. Gen. Educ., Ehime Univ.)
KASHIWAGI Toshisuke 18
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KATO Chihiro 110 Hi T ~ (Fac. Sci., Shinshu Univ.)
MATSUMOTO Haruhisa tl
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MUNAKATA Kazuoki
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MURAKAMI Hiroyuki f1" 1: 115- Z (Fac. Sci., Rikkyo Univ.)
NAGATA Katsuaki 7k E8 MJ SA (Fac. Eng., Tamagawa Univ.)
NAKAMOTO Atsushi ~i.!f (Fac. Sci., Rikkyo Univ.)
TAKASHIMA Takeshi ~ Ii!!i 1l (Fac. Sci. Eng., Waseda Univ.)
YAMAGIWA Iwao LlI ij:Pi Mf (Tobu High School)
YANAGIMACHI Tomoki 1~P my ~J3 it (Fac. Sci., Rikkyo Univ.)

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HOSHIDA Takashi £ IE ";=E; (Grad. Sch. Fac. Sci., Nagoya Univ.)
MIYASAKA Hiromasa g j£ 115- lE (Grad. Sch. Sci. Eng., Saitama Univ.)
Cyclotron Laboratory
AKIYOSHI Hiromichi f}( E ~ :7E*1
FUJITA Jiro Hi IEe~
FUKUNISHI Nobuhisa t~ [9 ~ foj*3
HIRUNUMA Rieko ft¥~llJiIT*5
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KAGEYAMA Tadashi J3 LlI lE
KATAYAMA Takeshi Jt LlI it: PJ*6
KOHARA Shigeo IJ, JJj( £ j(,
MORITA Kosuke ~ IE 115- 11'"NAKAGAWA Keiko I=f:l JII ~ T*l
NAKAJIMA Shunji I=f:l Ii!!i ~$OHNISHI Tetsuya
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SUZUKI Toshio &f;
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TAKANAKA Masao ~ f$ 1&
UESAKA Tomohiro 1: j£ 1J:. i$ * 1
WADA Takeshi *0 IE ftl*4
YANO Yasushige ~ If q;; £*7

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FUJITA Shin Hi IE *'f
GOTO Akira 1& Hi ~*4
ISHIDA Satoru ::0 IE '1~*1
IWASA Naohito :E 1ft ~ f= * 1
KASE Masayuki 110 ~ J§ Z
KIDERA Masanori~ lE
KUROKAWA Meiko ]l)ll ~ 1-*1
NAGASE Makoto ffi: it IDit
NAKAGAWA Takahide I=f:l JII ~ ~OGIWARA Kiyoshi ~ JJj( 1w
OTSUKA Takaharu~ ~ 15'*6
TAGAYA Yu ~110~ tt*2
UCHIYAMA Koji I*J LlI 115- ;=E;*2
UTSUNO Yutaka *t-~If ~*2
YAMAJI Shuhei LlI l1:a f~ If*4
YOKAYAMA Ichiro ;fl LlI - e~

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*1 Special Postdoctoral Researcher, *2 Junior Research Associate, *3 Contract Researcher,*4 Senior Scientist, *5 Postdoctoral Researcher, *6 Senior Visiting Scientist, *7 Chief Scientist276

(Visitors)
ABE Yasuhisa ~iiJ ~~ $)... (Yukawa Inst. Theor. Phys., Kyoto Univ.)~ (NASDA)ABURAYA Takashi i!H ~ARAKAWA Kazuo 5TE JII ~D ~ (JAERI, Takasaki Rad. Chern. Res. Estab.)
BABA Shinji .~ ~ g(NASDA)BANDYOPADHYAY Arup (Variable Energy Cycl. Cent., India)
BANDYOPADHYAY Tapas (Variable Energy Cycl. Cent., India)
BANERJEE Vaishali(Variable Energy Cycl. Cent., India)
BATYGIN Yuri
(Elect. Phys. Dept., Moscow Eng. Phys. Inst., Russia)
BHATTACHAYA Sankar (Variable Energy Cycl. Cent., India)
BIRI Sandor (ATOMKI, Hungary)
CHAKRABARTI Alok (Variable Energy Cycl. Cent., India)
CHATTOPADHYAY Subrata (Univ. Texas, Arlington, U.S.A.)DATE Schin #t j! {$ (JASRI)
DINH DANG Nguen g ~ ~3C (Inst. Nucl. Sci. Tech., Vietnam Atom Ener. Com., V~etnam)
EJIRI Hiroyasu
JK 7.i ~ (Fac. Sci., Osaka Univ.)
EN'YO Hideto M;.!:j- ~ A (Fac. ScL, Kyoto Univ.)
FUJIOKA Manabu Jfi [tUJ ~ (Cycl. Radioisot. Cent., Tohoku Univ.)
FUJISAWA Takashi Jfi rR ~ ~ (Denki Kogyo Co., Ltd.)FUJISHIMA Shiro Hi 1i!.; 9:. fm (LH.L)
FUJITA Yoshitaka Hi B3 it ¥f. (Fac. ScL, Osaka Univ.)
FUJIWARA Ichiro Hi JJj{ - ~~ (Dept. Economy, Otemon Gakuin)
FUJIWARA Mamoru Hi JJj{ ~ (RCNP, Osaka Univ.)
FUKUDA Mitsuhiro 1M B3 7t 9i (JAERI, Takasaki Rad. Chern. Res. Estab.)(Tandem Accel. Cent., Univ. Tsukuba)
FURUNO Kohe tJ ~ ~ f
FURUSE Kaoru tJ ~ ¥ (NASDA)
FUTAMI Yasuyuki~
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GOKA Tateo 11.
}t ~ (NASDA)
GRUBER Bruno (Tech. Univ. Clausthal, Germany)
GU Wei (Inst. Modern Phys., Academia Sinica, China)
HAMA Hiroyuki i~ Jt. ¥ (I.M.S.)
HARADA Toru JJj{ B3 ~~ (Sapporo Gakuin Univ.)
HASHIMOTO Miwa m ~ ~D (NASDA)
iEl (Fac. Sci., Tohoku Univ.)
HASHIMOTO Osamu m
HATANAKA Kichiji ~ffi 9J E iEl (RCNP, Osaka Univ.)(JAERI, Tokai Res. Estab.)
HATSUKAWA Yuichi *JJ JlI Ai HATTORI Toshiyuki mt ~~ f3e ¥ (Res. Lab. Nucl. React., Tokyo Inst. Technol.)
HAYANO Ryugo !f!. ~ Wi 11. (Fac. Sci., Univ. Tokyo)
HIRAO Yasuo f ij1 ~ ~ (N.LR.S)
HIROSE Takayuki Jt. ~ ¥f. ¥ (N ASDA)
HONMA Michio
rB~ ~ Ai
(Aizu Univ.)
HONMA ToshihirorB~ ~ Jt.
(Cycl. Radioisot. Cent., Tohoku Univ.)
HORIBATA Takatoshi #ill Jtffti ¥f. f3e (Fac. Eng., Aomori Univ.)
HORIGUCHI Takayoshi #ill 0 ~.& (Fac. Sci., Hiroshima Univ.)
HORIUCHI Hisashi #ffi r*J 7N! (Fac. Sci., Kyoto Univ.)
HOSONO Kazuhiko *Hl ~ ~D"& (Dept. Eng. Sci., Himeji Inst. Tech.)
IGARASHI Toshio 11.+i\1tt$ (NASDA)
IKEDA Akitsu nP. 83 t'<?$ (Shizuoka Inst. Sci. & Tech.)
IKEDA Kiyomi nP. B3 ~t ~ (Fac. Sci., Niigata Univ.)
IKEDA Nobuo at! B3 i$::K (Fac. Sci., Kyushu Univ.)
IKEZOE Hiroshi at! i~ tt (JAERI, Tokai Res. Estab.)(Fac. Sci., Kyoto Univ.)
IMAI Kenichi A, it ~ IN AMURA Takashi T. fiE ~t ~ (Former Staff of RIKEN)INOUE Makoto it 1: {'g (Inst. Chern. Res., Kyoto Univ.)
ISHIZUKA Takeo E ~ it ~ (Fac. Sci., Saitama Univ.)
ITO Yasuo #t Hi ~ ~ (Atomic Energy Res. Cent., Univ. Tokyo)
ITO Yoshiko #t
7i -=f (Adv. Res. Inst. Sci. & Eng., Waseda Univ.)
BB (JAERI, Tokai Res. Estab.)
IWAMOTO Akira :fi

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277

IWASHITA Yoshihisa :E r 7i ~ (Inst. Chern. Res., Kyoto Univ.)
IZUMOTO Toshiaki jjt
flJ ii! (ColI. Sci., Rikkyo Univ.)(High Energy Accel. Res. Organization)
JEONG S. C.
JIN Weigou ~00 (Pac. Sci., Toho Univ.)
KAMIMURA Masayasu 1:. ff iE 8Jt (Fac. Sci., Kyushu Univ.)
KANAZAWA Mitsutaka ~ ~R 7t ~ (N.I.R.S.)
KATAYAMA Ichiro f1 LiJ - ~~ (High Energy Accel. Res. Organization)
KATO Kiyoshi no Xi ~ 7i (Fac. Sci., Hokkaido Univ.)
KATO Shohei no ~ ~ ~ (Pac. Sci., Osaka Univ.)
KATORI Kenji J.l ~ ~(Fac. Sci., Osaka Univ.)
KATSURAGAWA Hidetsugu ;fi}ll 1§ rffim (Fac. Sci., Toho Univ.)
KAWAGUCHI Takeo )1\ 0 m: ~ (Mitsubishi Electric Co., Ltd.)KITAGAWA Hisashi ~t )11 rm (Inst. Phys., Univ. Tsukuba)
KOBAYASHI Misaki IJ'\
~ ~(Science Service Co., Ltd.)KOHAMA Akihisa IJ'\ il ?$:9<: (Fac. Sci., Univ. Tokyo)
KONDO Michiya ill: Xi J]! -ti1 (RCNP, Osaka Univ.)
KOTAJIMA Kyuya il83~~~ (Fac. Eng., Tohoku Univ.)
KOYEN Ali R.
(Univ. Texas, Arlington, U.S.A.)KUDO Hisaaki I Xi ~ BE (Fac. Sci., Niigata Univ.)
KUMATA Masayuki 1m 83 ~ Z (N .I.R.S.)
LEE Kong Ok
8Jt ± (Rika Women's ColI., Korea)
LEE Sang Mu;f§ Ji. (Inst. Phys., Univ. Tsukuba)#t ~ (RCAST, Univ. Tokyo)
LI Hongling(Inst. Modern Phys., Academia Sinica, China)
LIU Sheng Li
MAEDA Kazuhide 1W 83 *0 1§ (Fac. Sci., Kyushu Univ.)
MATSUDA Sumio l~ 83 k4! ~ (NASDA)
MATSUI Yoshiko f~ #- 7i::r (Pac. Tech., Agri. Tech., Univ. Tokyo)
tiE 5e. (Inst. Chern. Res., Kyoto Univ.)
MATSUKI Seishi f',t}
MATSUMOTO Akihiro f',t}
B)'t i$ (NASDA)
MATSUSE Takehiro f',t} li ::t i1!f (Fac. Textile Sci. Tech., Shinshu Univ.)(Fac. Sci., Kyoto Univ.)
MATSUYANAGI Kenichi ;f~;fPP M (Fukuoka Univ. Ed.)
MATUZAKI Masayuki ;f~ 1iJ~ ~ Z
MENG Jie
MINAMISONO Tadanori
III ,~, ~Ij (Fac. Sci., Osaka Univ.)
MITSUMOTO Toshinori ~~ ~(Sumitomo Heavy Industries, Ltd.)(RCNP, Osaka Univ.)
MIURA Iwao .::: iii E-ti1 (KEK)MIYATAKE Hiroari '8 m:
ff ~ Z(RCNP, Osaka Univ.)
MIZUNO Yoshiyuki
MIZUSAKI Takahiro
1iJ~ ~ i!
(Fac. Sci., Univ. Tokyo)
MORI Yoshiharu ~ ~ it (KEK)
MORIKAWA Tetsuya ~ )11 ~ -ti1
MOTONAGA Shoushichi 5C 71<. BE -t (Former Staff of RIKEN)MUKHOPADHTAY M.
(Variable Energy Cycl. Cent., India)
MURAKAMI Hideoki ff 1:. "!Ii:. ~ (Tokyo Gakugei Univ.)
MURAKAMI Tetsuya ff 1:. =fg' -ti1 (Fac. Sci., Kyoto Univ.)
MURAYAMA Toshiyuki ff LiJ flJ ¥ (Univ. Tokyo, Mercantile Marine)
MUTO Kazuo m: ~ - 1$ (Fac. Sci., Tokyo Inst. Technol.)
NAGAFUCHI Teruyasu 7k 7tH .lfR 8Jt (Toshiba Corp.)
NAGAI Yasuki 7k #- ~ 1it (Fac. Sci., Tokyo Inst. Technol.)NAGAI Yuki 7k #- E8 if.2. (NASDA)
NAKADA Hitoshi ~ 83 {= (ColI. Art & Sci., Chiba Univ.)
NAKAHARA Hiromichi ~)Jj{ ~t. J]! (Fac. Sci., Tokyo Metrop. Univ.)(Fac. Sci. Tech., Sci. Univ. Tokyo)
NAKAI Ko-zi ~ #- i!
NAKAMURA Hiroyuki ~ ff fit Z (Fac. Sci., Kyushu Univ.)
NAKAMURA Ichiro ~ ff rtf ~~ (Fac. Sci., Saitama Univ.)
NAKAMURA Takashi ~ ff rm R] (Cycl. Radioisot. Cent., Tohoku Univ.)
NAKAO Noriaki ~ ~ ~ ~ (KEK)
NAKASHIMA Hiroshi ~!if!s(JAERI, Tokai Res. Estab.)

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NODA Akira mf 83 •(Inst. Chern. Res., Kyoto Univ.)
NODA Kouji mf 83 fjf P] (N.I.R.S.)NOMURA Toru !f fr ~ (KEK)NOZAKI Tad as hi !f ~~ 1£ (Kagami Memorial Lab., Materials & Sci., Waseda Univ.)
OGAWA Kengo IJ~)l1 1l::g. (Dept. Eng., Sci., Himeji Inst. Tech.)
OHIRA Hideharu
Sf(NASDA)
OHKAWA Tomohiro)11 ~ 7i (Mitsubishi Heavy Industries, Ltd.)OHNISHI Naoki[§ W! ~ (ColI. Art Sci., Univ. Tokyo)
OHTOMO Kiyotaka
0:. 1t ~ (Sumitomo Heavy Industries, Ltd.)OHTSUKI Tsutomu
1!1l fJJ (Lab. Nuel. Sci., Tohoku Univ.)fk~~ (NASDA)
OHYA Jiro
OKAMOTO Hiromi f8iJ
7i E. (Inst. Chern. Res., Kyoto Univ.)
OKAMURA Hiroyuki f8iJ fr 51.. Z (Fae. SeL, Univ. Tokyo)
OKUMURA Susumu J!: fr :i1t (JAERI, Takasaki Rad. Chern. Res. Estab.)
OOTOMO Hiromitsu
0:. i$ 7t (NASDA)OTA Kiyoshi
B3 1t (Fae. Sci., Saitama Univ.)
PERSSON Jonas
SAGARA Kenshi if§'&' 1t ~ (Fae. Sci., Kyushu Univ.)
Ml.=: (Former Staff of RIKEN)
SAITO Motozo~ q-y(Fae. Sci., Univ. Tokyo)
SAKAI Hideyuki 7~
SAMBATARO Michelangelo(I.N.F.N., Catania)
SATO Ken-ichi {1:. ~ (Dept. Phys., Tohoku ColI. Pharm.)(RCNP, Osaka Univ.)
SATO Kenji 1~. 1l
SATO Yukio {1: Ji $ ~ (N.I.R.S.)
SEKINE Toshiaki 1*1 fl ~ ~ (JAERI, Tokai Res. Estab.)
SHIBATA Tokushi ~ B3 f!re ,![!" (KEK)
SHIKAZONO Naomoto J1[ 1/ W! ~ (JAERI, Tokai Res. Estab.)
SHIMIZU Akira 1t
BB (RCNP, Osaka Univ.)
SHIMOMURA Kouichiro Tfri~-~~ (Meson Sci. Lab., KEK Brunch, Univ. Tokyo)
SHIN Kazuo ~ *0 ~ (Fae. Eng., Kyoto Univ.)~(Rika Women's College, Korea)
SHIN Seung Ai $SHINDO Hiroyuki
i~ Z(NASDA)SHINOZUKA Tsutomu ~ ~ $frJl (Cyel. Radioisot. Cent., Tohoku Univ.)
SHIRAI Toshiyuki B # fU!I. Z (Nuel. Sci. Res. Fae., Inst. Chern. Res., Kyoto Univ.)
SHIROV Grigori(J .I.N .R., Dubna)
SHUGYO Shin-ichi 1~ q-y fJf (NASDA)
SIDORIN Anatoly(J.I.N.R., Dubna)§ 1r (Fae. Sci., Tokyo Metrop. Univ.)
SUEKI Keisuke
SUGAIIsao ;g #~(KEK)SUGn Kazuo tb # - ~ (Osaka Vacuum, Ltd.)~ 16 (NASDA)
SUGIMOTO Kenji ;fb
SUGIYAMA Hiroki tb LlJ *:tit (NASDA)
SUMIYOSHI Hiroyuki 11 =g Jt. q-y (Matsusho-Gakuen Junior ColI.)~ ~(ColI. Sci. Tech., Nihon Univ.)
SUZUKI Toshio ~SUZUKI Takahiro jiJ~ tf(NASDA)SYRES SINE Evgueni(J.I.N.R., Dubna, Russia)
TAGISHI Yoshihiro B3 J¥ ~ 7i (Tandem Aeeel. Cent., Univ. Tsukuba)
TAJIMA Naoki B3 ~~ W! 1M (ColI. Art Sci., Univ. Tokyo)
TAKADA Masashi ~ 83 • ~ (N.I.R.S.)
i& ~ ± (Kyoto Univ. Edu.)
TAKEMASA Tadashi
Jt. (JAERI, Tokai Res. Estab.)
TAKEUCHI Suehiro ¥r I*J
TAKIGAWA Noboru ~)l1 ,Jt (Fae. SeL, Tohoku Univ.)
TAMAGAKI Ryozo 3£:ill.&.'=: (Fae. Sci., Kyoto Univ.)(Otsuma Women's ColI.)
TANABE Kazuko B3 ill
TANABE Kousai EH ill1f. -§It (Fae. Sci., Saitama Univ.)
TANAKA Jinichi EH 9J t:(KEK)
TANAKA Kazuhiro B3 9J *0 J1( (Medical Dept., Jyuntendo Univ.)
TANAKA Yasushi B3 9J 1* ~ (Kyokuto Boeki Kaisha, Ltd.)

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TANIKAWA Masashi ~}l1 JJJ ~ (Fac. Sci., Univ. Tokyo)
TOHYAMA Mitsuru Ji LlJ frd9 (Kyorin Univ.)
TOMIMASU Takio ~t~~%~ (Free Electr. Laser Res. Inst. Inc.)TOMINAKA Toshiharu 1i Ji:l flJ is (Hitachi, Ltd.)TOMITANI Takehiro ~ 1t
i1'f (N.I.R.S.)
TOMIZAWA Masahito glE A (KEK)
TOMODA Toshiaki 1ft:. EE ti& ~ (Fac. Eng., Aomori Univ.)
TOPREK Dragan(VINCA, Inst. Nucl. ScL, Yugoslavia)
TORIYAMA Tamotsu ,~LIJ(Dept. Phys., Musashi Inst. Technol.)~Ij ¥(NASDA)TSUBAKI Noriyuki
TSUKINO Akihisa }3 If ~ ~ (NASDA)UTSUNOMIYA Hiroaki *t~§~.l.. (Fac. ScL, Konan Univ.)
WADA Michiharu *0 EH jg is (KEK)
WADA Ryoichi *0 EE ~ (Texas A & M Univ., U.S.A.)
WADA Takahiro *0 83 iii 7i (Fac. ScL, Konan Univ.)
WAKAI Masamichi ~ it IE jg (Pac. Sci., Osaka Univ.)
WAKUTA Yoshihisa *0~83~~ (Fac. Eng., Kyushu Univ.)
WATANABE Ikuo Vi ill fl~ ~ (Toshiba Corp.)
WATANABE Shin-ichi Vi ill {$ (Cent. Nucl. Study, Grad. Sch. Sci., Univ. Tokyo)
WU Dezhong(Inst. Modern Phys., Academia Sinica, China)
YABANA Kazuhiro ~ 1t. - i1'f (Pac. Sci., Niigata Univ.)
YAMANOUCHI Mikio LIJ I*J ~ 1$ (Inst. Phys., Univ. Tsukuba)
YAMAZAKI Hirohito LIJ Ih~ )t 1= (Lab. Nucl. ScL, Tohoku Univ.)
YAMAZAKI Takashi LIJ Ih~ ft (RCNP, Osaka Univ.)
YOKOUCHI Shigeru
I*J a: (Osaka Vacuum, Ltd.)YONEDA Akira
83 ~YONEMARU Mitsunori
JL 7E m (NASDA)YOSHIDA Nobuaki E 83 '§" ~ (Fac. Sci., Univ. Tokyo)
YOSHINAGA Naotaka E 7K rt6 i!f: (Pac. Sci., Saitama Univ.)
YOSHIOKA Yasuhiro E [tliJ BJt~.l. (NASDA)YOSHIZAWA Yasukazu E iR BJt *0 (Fac. Eng. , Kyushu Univ.)
YUAN Ping(Inst. Modern Phys., Academia Sinica, China)
ZHANG Wenzhi(Inst. Modern Phys., Academia Sinica, China)

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AOKI Yuka W
ill W (Grad. Sch. Sci., Tohoku Univ.)
ARIGA Takehiro 1i jt it tf (Fac. Sci., Saitama Univ.)
FUJITA Tatsuru Ii- 83 Jt (Interdisciplinary Grad. Sch. Eng. ScL, Kyushu Univ.)
HASHIMOTO Satoshi ~Jf (Dept. Phys., Grad. Sch. ScL, Univ. Tokyo)
KIM Eun Joo(Grad. Sch. Sci., Tohoku Univ.)
KINOSHITA Tadashi
r ,'i1', (Grad. Sch. ScL, Tohoku Univ.)
KURITA Tetsuro ~ EH tg" ~~ (Inst. Phys., Univ. Tsukuba)
KUROSAWA Tadahiro ~,'i1',~.l.
(Grad. Sch. Sci., Tohoku Univ.)
NAKAO Makoto Ji:l ~ ~ (Grad. Sch. Sci., Tohoku Univ.)
OGATA Kentaro *fJJ.pjf:t:~~ (Pac. Sci., Kyushu Univ.)
01 Makito *it7J~A (Grad. Sch. Arts Sci., Univ. Tokyo)
OKUDA Hikaru ~ EH -Jt (Fac. ScL, Kyushu Univ.)
OSHIMA Nagayasu
Jib 7K(Grad. Univ. Adv. Stud.)
OZAWA Shuichi IJ'\
1~ (ColI. Sci., Rikkyo Univ.)
SASAKI Michiya 1:t4*jgi:t1 (Grad. Sch. Sci., Tohoku Univ.)
SHIGENAGA Kouichi ~ 71<. ~ (Fac. ScL, Kyushu Univ.)
SONE Hayato ~ tl ~ A (Fac. Sci. Tech., Sci. Univ. Tokyo)
TANIGUCHI Shingo 1t 0 • ~ (Grad. Sch. Sci., Tohoku Univ.)
TSURUTA Kaoru U 83 1i (Interdisciplinary Grad. Sch. Eng. ScL, Kyushu Univ.)WAKUI Takashi i~ itit- (Pac. Sci., Toho Univ.)
YAGITA Takanori )\*83:l~ (Fac. ScL, Kyushu Univ.)

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CHIBA Toshiya T ~ flJ ~FUKUDA Shigekazu 1M 83 7J. _*1
IKEZAWA Eiji 7th ¥R ~KOBAYASHI Toshio IJ'\
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KUMAGAI Hidekazu 1f~ ~ ~ fo
MIYAZAWA Yoshitoshi '§ rR {* ~MOMOTA Sadao B83ft~~*l
OHTSU Hideaki
if ~ 11)'£*1SUZUKI Takeshi ~~TONUMA Masao p r?j lE a

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FU JIMAKI Masaki JJi ~ lE lit
HEMMI Masatake ~ Ji ift m:
KASE Masayuki nD it ~ Z
KORSHENINNIKOV Alexei
KUSAKA Kensuke B r • :.f,tj
MOCHIZUKI Yuko S. f{1 J1 ~ -=f*1
OGAWA Yoko IJ'\)II r$ -=f*1
OZAWA Akira IJ'\ ¥R 1ft
TANIHATA Isao ~ iHl ~ ~*4
YOSHIDA Koichi 15 83 Jt -*2 Senior Scientist,*3 Postdoctoral Researcher,*4 Chief Scientist(Visitors)
ADACHI Shizuko ~ Ji ijj T (ICFD)
AHMADY Mohammad (Western Ontario Univ., Canada)
ARATANI Michi 5TE ~ ~ ~ (Inst. Enviromental Sci.)
BOLBOT Michael (Notre Dame Univ., U.S.A.)
BOYD Richard (Ohio Univ., U.S.A.)
BROCKMANN Roff (Inst. Phys., Univ. Mainz, Germany)
DAVID Dean J . (CALTEC, U.S.A.)
DEMYANOVA Alla S.
(Kurchatov Inst. Atomic Energy, Russia)
FUJIWARA Mamoru Ki mt ~ (RCNP, Osaka Univ.)
FULOP Zsolt (ATOMKI, Hungary)
GOLOVKOV Mkheil S.
(Kurchatov Inst., Russia)
GONCHAROV Sergei A.
(Kurchatov Inst., Russia)
HIRENZAKI Satoru B it~~ 't-! (Fac. Sci., Nara Women's Univ.)
HORIUCHI Hisashi #ill r*J 7N! (Fac. Sci., Kyoto Univ.)
BB (JAERI, Tokai Res. Estab.)
IWAMOTO Akira :6
IZUYAMA Takeo flJjfLlI~~ (Fac. Sci., Toho Univ.)
KATORI Kenji Jl[ ~ ~(Fac. Sci., Osaka Univ.)
KIKUCHI Jun ?lID 1& JIIJl (Sci. Eng. Res. Lab., Waseda Univ.)
KIMURA Kikuo *ift:@:j\a (Fac. Eng., Nagasaki Inst. Appl. Sci.)
KOLATA James(Notre Dame Univ., U.S.A.)MARUYAMA Tomoyuki J:L LlI ~ Z (Fac. ScL, Kyoto Univ.)
MATSUTA Kensaku t~ ~ ~ jfi (Fac. Sci., Osaka Univ.)
MATSUYAMA Yoshitaka fi} LlI 7r -if: (Inst. Nucl. Study, Univ. Tokyo)
MATUOKA Nobuyuki t~ WiJ {$ q:y (Res. Cent. Nucl. Phys., Osaka Univ.)
MITTING M.
(GANIL, France)
MIYAKE Yasuo =: ij£3 ,*.e~ (Fac. ScL, Univ. Tsukuba)
MIYAMURA Osamu '§ ift {~ (Fac. Sci., Hiroshima Univ.)
MOCHIZUKI Keiko f{1 J1
T (Fac. Sci., Osaka Univ.)¥ R] (JST)MORIMOTO Koji ~MURAOKA Mitsuo ift WiJ Jt:!1J (Fac. Eng., Aomori Univ.)(Kochi Univ. Technol.)
NOJIRI Yoichi If JJL r$ OGAWA Kengo IJ'\)lI.:g. (Coll. Arts. Sci., Chiba Univ.)
OGLOBLIN Alexei A.
(Kurchatov. Inst. , Russia)i!§'ij£3 (Fac. Sci., Hokkaido Univ.)
OHNISHI Akira
i'f ~ (Fac. Sci., Niigata Univ.)
OHTSUBO Takashi
OJIMA Minoru IJ'\ ~,~ fl: (Fac. Sci., Osaka Univ.)
OMATA Kazuo IJ'\ {~ fo ~ (Inst. Nucl. Study, Univ. Tokyo)
ORYU Shinsho ~ fL 1f 1* (Fac. Sci. and Tech., Sci. Univ. Tokyo)
OYAMATSU Kazuhiro mt~ fo riff (Dept. Energy Eng. Sci., Nagoya Univ.)
PETRASCU Horia (Inst. Phys. Nucl. Eng., Romania)
PETRASCU Marius (Inst. Phys. Nucl. Eng., Romania)
RAIMANN Gerhard (Ohio State Univ., U.S.A.)

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281

SAGAWA Hiroyuki iii:)l1 ~J.,. ¥ (Cent. Mathematical Sci., Aizu Univ.)
SAKAI Hideyuki ?~ 1f ~ fr (Fac. Sci., Univ. Tokyo)
SATO Kazuhiro 1tL ni
It. (Tokyo Fire Dept.)
SEKI Ryoichi ~ 7C (California Univ., U.S.A.)SHERRIL B.
(Michigan State Univ., U.S.A.)
SUDA Toshimi ~J{ 83 flJ ~ (Fac. Sci., Tohoku Univ.)
SUGANUMA Hideo ~ ¥B ~ ~ (RCNP, Osaka Univ.)~ ~(Fundam. Sci., Chiba Inst. Technol.)
SUGAWARA Masahiko ;g
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(KEK)
SUZUKI Hideyuki ~f]
SUZUKI Tsuneo if]tg(Fac. Sci., Kanazawa Univ.)
SUZUKI Yasuyuki ~f]'§" Z(Fac. Sci., Niigata Univ.)
TACHIBANA Takahiro f~ -1f. tf (Senior High School of Waseda Univ.)
TAKAHASHI Yoshiyuki ~ tift ¥ (Alabama Univ., U.S.A.)
TAKAHASHI Yutaka ~ tl -=. (Fac. Sci., Osaka Univ.)
TOKANAI Fuyuki r~ pt ~ ftj (JST)TOKI Hiroshi ± II!t tf (RCNP, Osaka Univ.)TORBJOEN Baeck (Stochholm Univ., Sweden)
VARGA Kalman(Inst. Nucl. Res., Hungarian Acad. Sci., Hungary)
WADA Takahiro
83 ~(Fac. Sci., Konan Univ.)
i1!i'iIJ (Fac. Sci., Univ. Tsukuba)
YAGI Hirosuke )\YORANN Alhassid(Yale Univ., U.S.A.)ZAHAR Mohamed (Dept. Phys., Notre Dame Univ., U.S.A.)

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BOKU Yudan~ ~(Fac. Sci. Eng., Waseda Univ.)
FUKUDA Naoki f~ 83 @::fit (Fac. Sci. Eng., Waseda Univ.)
HIBINO Masaru Bltff if! (Fac. Sci. Eng., Waseda Univ.)
HIYAMA Emiko ~~LlJ~~-=f (Pac. Sci., Kyushu Univ.)
HONG Wang #t ft (Fac. Eng., Univ. Tokyo)
IKEDA Takayuki ?tl! 83 ~ Z (Grad. Sch., Osaka Univ.)
ISHIGA Kenichi E ~ 1l (Grad. Sch., Osaka Univ.)
KABURAGI Akira 1m~(Grad. Sch., Waseda Univ.)
KANO Kenji pt ~ ¥8 (Fac. Sci., Univ. Tsukuba)
KATO Toshiyuki
ni 1& $ (Fac. Sci. Eng., Waseda Univ.)
F9(Fac. Sci., Saitama Univ.)
KIUCHI Hiroshi
KONO Sachiko Ef3 ff ~ -=f (Fac. Sci. Eng., Waseda Univ.)
KOZU Tomotake f$ if: IX m: (Fac. Sci. Eng., Waseda Univ.)
MARUYAMA Yukiko 1LUlI:Eif.2.-=f (Fac. Sci., Osaka Univ.)~ -=f(Fac. Sci. Eng., Waseda Univ.)
MATSUMOTO Akiko t~
MIKI Keitaro =*~:;tJ~~ (Fac. Sci., Konan Univ.)
OZAKI Kiminori ~ lIltj 0: ~ (Fac. Sci. Eng., Waseda Univ.)
SAITO Masanori ~ Hi lE)I (Fac. Sci., Osaka Univ.)
SAKAGUCHI Takao :t& D .. ~ (Fac. Sci. Eng., Waseda Univ.)
SHIMOOKA Masaaki r IiYiJ iE ~ (Fac. Sci., Kyoto Univ.)
TAKAHASHI Yoshiyuki ~ flft ¥ (Fac. Sci. Eng., Waseda Univ.)
TAKAHASHI Kenichi j'@j fl If (Grad. Sch., Waseda Univ.)
TAKEHANA Naohiro 11' 1E @: ~J.,. (Fac. Sci. Eng., Waseda Univ.)
TAKENAKA Sunao 11' ~ @: (Fac. Sci. Eng., Waseda Univ.)
TERUHI Shigeru .~ B ~ (Fac. Sci. Eng., Waseda Univ.)
WANG Haiming 1: #i ~~ (Fac. Sci., Univ. Tokyo)
YAMASHITA Akira LlJ r
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BEAUMEL Didier* 1
GOTO Yuji f& Hi*2
HAYASHI Naoki 1* @: ftj*2
I CHIHARA Takashi rtf!j[ *4

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HAHN Kevin I.*2
HIRAI Masaaki ~ 1f lE ~*3
IDEGUCHI Eiji 1f=¥-D*¥8*2

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KURITA Kazuyoshi ~ 83 *0 ~f*2
MIZOI Yutaka 7. #¥'t1*2
OHTA Shigemi
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OOYAMA Ken
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SAKURAI Hiroyoshi l~ # tt 1ft
WATANABE Yasushi iJi 31
YANAGISAWA Yoshiyuki ~p ¥R # ff*3

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KISHIDA Takashi
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MATSUKI Tsuneki ;f'~1it :flj*3
NOTANI Masahiro ff ~ ~~ Jt*2
OKAMURA Masahiro ltliJ:tt ~ 2*2
SAITO Naohito ~ Ii ~ A
TERANISHI Takashi # iffi ~*2
WATANABE Yutaka ill ill 1it*3
YOSHIDA Atsushi
83 ~a*3 Junior Research Associate,*6 Visiting Researcher(Visitors)
ABE Yasuhisa ~iiJ tf~ ~).... (Yukawa Inst. Theor. Phys., Kyoto Univ.)(Fac. Sci., Tokyo Inst. Technol.)
ADACHI Minoru JE
ANDO Yoshiaki 1i: Hi a:$: (ColI. Sci., Rikkyo Univ.)
ASAHI Koichiro 1ili. fjj:-~~ (Fac. Sci., Tokyo Inst. Technol.)
AWAYA Yoko ~ ~ ~ r(Musashino Art Univ.)
BECK F. A.
(CRN, France)
BROGLIA R.
(Dept. Phys., Univ. Milano, Italy)
CASTEN Rick (Dept. Phys., Brookhaven Natl. Lab., U.S.A.)
CHRIST Norman H.
(Dept. Phys., Columbia Univ., U.S.A.)~(Inst. Phys., Univ. Tsukuba)
DOOI Makoto £ #EN'YO Hideto }Jf l} ~ A (Fac. Sci., Kyoto Univ.)
FLOCARD Hubert(Div. Phys. Theor., lPN, France)
FUCHI Yoshihide i~J fjf ~ (Inst. Nucl. Study, Univ. Tokyo)
FUKUDA Mitsunori 1~ 83 7t Jllft (Grad. Sch. Sci., Osaka Univ.)
FUKUDA Tomokazu 1~ 83 ;tt. *0 (Inst. Nucl. Study, Univ. Tokyo)
FURUTAKA Kazuyoshi r!J ~ *0 1it (JAERI, Adv. Sci. Res. Cent.)
HAMAGAKI Hideki i~ m ~ ti-r (Cent. Nucl. Study, Univ. Tokyo)
1f r (Dept. Theor. Phys., Lund Univ., Sweden)
HAMAMOTO Ikuko i~
HASEGAWA Takeo *~JlllEe~ (Fac. Eng., Miyazaki Univ.)
HATSUDA Tetsuo :M 83 ~ ~ (Inst. Phys., Univ. Tsukuba)
ICHIMURA Munetake m:ttlEe (Grad. Sch. Arts & Sci., Univ. Tokyo)
IEKI Kazuo~ *0 ~ (CoIl. Sci., Rikkyo Univ.)
IWASA Naohito :B 1ti: ~ {= (Lab. Nucl. Studies, Fac. Sci., Osaka Univ.)
IZUMI Hideaki ill 71< ~ ~ (Fac. Sci., Grad. Sch. Sci., Osaka Univ.)
KAMAE Tsuneyoshi ~ iI 1it ~f (Dept. Phys., Grad. Sch. Sci., Univ. Tokyo)
KASAGI Jirota ~*is~~"* (Lab. Nucl. Sci., Tohoku Univ.)
KATAYAMA Ichiro h ill - ~~ (Cent. Nucl. Study, Univ. Tokyo)
KATO Seigo 1m Hi • ~ (Fac. Edu., Yamagata Univ.)
KATORI Kenji n¥: 1tt [t(Lab. Nucl. Studies, Fac. Sci., Osaka Univ.)
KIM Jong Chan ~ ~l(Dept. Phys., Seoul Natl. Univ., Korea)
KITAO Kensuke %~ f=t ~WJ (Data Eng. Inc.)~~(Fac. Sci., Hiroshima Univ.)
KODAIRA Jirou 11', Sf
KOIKE Yuji IJ'\ 7th 1it P] (Fac. Sci., Niigata Univ.)(Dept. Phys., Univ. Milano)
KOSOWER David A.
KUBONO Shigeru j.,.i~ff tt (Cent. Nucl. Study, Univ. Tokyo)
KUMANO Shunzo ~~ ff it =: (Fac. Sci. and Eng., Saga Univ.)
KUSAKARI Hideshige Ji. ~U ~ ~ (Fac. Edu., Chiba Univ.)
LEE Sang Mu;tEl tt (Inst. Phys., Univ. Tsukuba)
LIU Xin (Cent. Nucl. Study, Univ. Tokyo)
LIU Zhong (Inst. Mod. Phys., Acad. Sinica, China)
LOUKIANOV Serguei (Flerov Lab. Nucl. Reactions, JINR, Russia)
MAEDA Kazushige frj 83 *0 a (Grad. Sch. ScL, Tohoku Univ.)
MAO Yajun (Dept. Nucl. Phys., China Inst. Atom. Energy, China)
MATSUDA Satoshi ;f'~ 83 tg" (Dept. Fundamental Sci., Fac. Integrated Human Studies, Kyoto Univ.)
MATSUI Tetsuo ;f'~ # tg" ~ (Yukawa Inst. Theor. Phys., Kyoto Univ.)

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MENGONI Alberto
MITARAI Shiro fijJ~r)t=t-e~ (Fac. Sci., Kyushu Univ.)
MITSUOKA Shinichi -Jt WiJ ~ ~ (JAERI)MIYACHI Takashi g f& "If- (Cent. Nucl. Study, Univ. Tokyo)
MIYATAKE Hiroari g-m (Inst. Particle Nucl. Phys., KEK)MORII Toshiyuki ~ # 13e iT (Fac. Human Develop., Kobe Univ.)
MORIKAWA Tsuneyasu ~ JII '@ 17:: (Dept. Phys., Fac. Sci., Kyushu Univ.)
MORINOBU Shunpei ~ 1§' ~ f(Dept. Phys., Fac. Sci., Kyushu Univ.)
MOTOBAYASHI Toru 7.$:~
(Dept. Phys., ColI. Sci., Rikkyo Univ.)
MOTTELSON Ben R.
(NORDITA, Nordisk Inst. Teoretisk Fysik, Denmark)
MUELLER Ludwig(Phys. Dept., Univ. Padova, Italy)
MURAKAMI Takeshi if;J J:. -&t (Natl. Inst. Radiol. Sci.)
NAGAI Yasuki 7]( # ~ ~f (Fac. Sci., Tokyo Inst. Technol.)NAGASHIMA Yasuo
lib ~ ~ (Inst. Phys., Univ. Tsukuba)
NAKAMURA Takashi 9=t if;J ~ 1§1 (Dept. Phys., Grad. Sch. Sci., Univ. Tokyo)
NAKAMURA Msanobu 9=t if;J 1£ 1~ (Fac. Sci., Kyoto Univ.)
NAKAYAMA Shintaro 9=t LiJ1~*e~ (Fac. Integurated Arts and Sci., Tokushima Univ.)
NIIZEKI Takashi ~ I*l ~ (Fac. Sci., Tokyo Inst. Technol.)
NORO Tetsuo ~ g =g::K (Res. Cent. Nucl. Phys., Osaka Univ.)
ODAHARA Atsuko IJ'\83W-J!t-1- (Nishinippon Inst. Tech.)
OGAWA Masao IJ'\ JII ~ ~ (Interdisciplinary Grad. Sch. Sci. Eng., Tokyo Inst. Technol.)
OKAMURA Hiroyuki WiJ if;J ~t. Z (Dept. Phys., Grad. Sch. Sci., Univ. Tokyo)
ORIHARA Hikonojyo ~W-~ZzjS (Cycl. Radioisot. Cent., Tohoku Univ.)
OSHIMA Masumi~ ~ M (JAERI, Adv. Sci. Res. Cent.)
OTSUKA Takaharu~ "If- 1S(Dept. Phys., Grad. Sch. Sci., Univ. Tokyo)
PENIONJKEVITCH Yuri
(Flerov Lab. Nucl. Reactions, JINR, Russia)
SAGAWA Hiroyuki 1:t}l1 ~t. =$ (Cent. Mathematical Sci., Aizu Univ.)
SAKAGUCHI Harutaka ~ D 1S ~ (Fac. Sci., Kyoto Univ.)
SAKAI Mitsuo ~ # 7t::K (Univ. Tokyo)
SAKURAGI Hiroyuki t~~t. Z(Fac. Sci., Osaka City Univ.)
SATO Hiroshi ftc ni !It (Seikei Univ.)
SATO Hikaru ftc ni B~ (KEK)
SCHAEFER Markus(Physicalisches Inst., Goettingen Univ., Germany)
SCHMIDT-OTT Wolf-Dieter(Physicalisches Inst., Goettingen Univ., Germany)
SHIBATA Toshiaki ~ ill llJ I¥J (Fac. Sci., Tokyo Inst. Technol.)
SHIMIZU Hajime(Fac. Sci., Yamagata Univ.)
SHIMIZU Yoshifumi'&)C (Fac. Sci., Kyushu Univ.)
SHIMODA Tadashi T ill 1£ (Grad. Sch. Sci., Osaka Univ.)
SHIMOURA Susumu T?ffl ~ (ColI. Sci., Rikkyo Univ.)
SIGNORINI Cosimo(Phys. Dept., Univ. Padova, Italy)
SUGAWARA Masahiko 'if JJ?: ~ ~ (Chiba Inst. Technol.)SUZUKI Masayo ~fl~ itt (JASRI)SUZUKI Yasuyuki ~flli Z (Fac. Sci., Niigata Univ.)
TAJIMA Yasuhisa ill ~ ~fi ~ (Cycl. Radioisot. Cent., Tohoku Univ.)
TAKADA Eiichi ~ 83~
(Natl. Inst. Radiol. Sci.)
TAKAHASHI Noriaki i@j tl )I I¥J (Grad. Sch. Sci., Osaka Univ.)
TAKAHASHI Tadayuki ~ tl ,~, =$ (Inst. Space and Astronautical Sci.)
TAKIGAWA Noboru ~~ JII jt (Grad. Sch. Sci., Tohoku Univ.)
TANAKA Masahiko 83 9=t ~ ~ (Inst. Nucl. Study, Univ. Tokyo)
TANOKURA Atsushi ill~~ ft (Fac. Sci. Technol., Sophia Univ.)
TERAKAWA Atsuki ~}II"(Cycl. Radioisot. Cent., Tohoku Univ.)
THOMPSON Ian Joseph(Phys. Dept., Univ. Surrey, U.K.)
TOKI Hiroshi ±!ij: t.f (Res. Cent. Nucl. Phys., Osaka Univ.)
TOYOKAWA Hidenori -=- JII 1§ WII (JASRI)
UENO Hideki J:. ~ 1§(Lab. Nucl. Studies, Fac. Sci., Osaka Univ.)
UNO Masahiro
If lE 9i (Ministry Edu., Sci. Culture)
WAKAMATSU Masashi t= t~ lE ~ (Lab. Nucl. Studies, Fac. Sci., Osaka Univ.)

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WU Heyu R {[](Inst. Mod. Phys., Acad. Sinica, China)
YAMAMOTO Sukeyasu L.IJ
~t Ji~(Fac. Sci. Technol., Sophia Univ.)
YAMANISHI Teruya L.IJ [§ ~ -ti1. (Fac. Eng., Fukui Univ. Technol.)
YOSHINAGA Naotaka E 7k raJ 'if. (Fac. Sci., Saitama Univ.)YOSOI Masaru ~~if 11 (Fac. Sci., Kyoto Univ.)
ZHOU Xiao Hong mJ IJ-. *1 (Inst. Mod. Phys., Acad. Sinica, China)*(Students)
AOI Nori 1f if ~ (Dept. Phys., Grad. Sch. Sci., Univ. Tokyo)
FUJIOKA Hiroyuki Hi Wi] tf ¥ (Dept. Phys., Grad. Seh. Sci., Univ. Tokyo)
FUKAI Atsushi i* if ~ (CoIl. Sci., Rikkyo Univ.)
FUKUDA Naoki fi ill ~:fij (Dept. Phys., Grad. Sch. Sci., Univ. Tokyo)
FUKUSAKA Shoichi fi ~ ~q (Dept. Phys., Grad. Seh. Sci., Univ. Tokyo)
GOMI Tomoko Ii ~ HJI -=f (CoIl. Sci., Rikkyo Univ.)
HAYASHIGAKI Arata ;ft m ~ (Fae. Sci., Niigata Univ.)
HIGURASHI Yoshihide 8 ~ :f$ ~ (CoIl. Sci., Rikkyo Univ.)
HIRAI Masanori ~ if iE ii':2. (Fac. Sci., Saga Univ.)(ColI. Sci., Rikkyo Univ.)
HIROSHIMA Tomotsugu 1Ji ~,~ 17:.
HISANAGA Isamu ~ 7k ~ (CoIl. Sci., Rikkyo Univ.)
HORIKAWA Hirotsugu #iIl)l[ tf HRm (Fae. Human Development, Kobe Univ.)
IMAI Nobuaki 4'- if 1$ BJ3 (Dept. Phys., Grad. Seh. Sci., Univ. Tokyo)
ITO Kazuya #t Ki {[l -ti1. (Grad. Seh. Sci., Tohoku Univ.)
IWASAKI Hanako :!fi ~~ • -=f (CoIl. Sci., Rikkyo Univ.)
IWASAKI Hironori :!fi 1iJ~ "5]" ~ (Dept. Phys., Grad. Sch. Sci., Univ. Tokyo)
IWATA Yoshiyuki :!fi ill 1* Z (CoIl. Sci., Rikkyo Univ.)
KIJIMA Takeshi~
3t (CoIl. Sci., Rikkyo Univ.)(CoIl. Sci., Rikkyo Univ.)
KOBAYASHI Hiroshi IJ-.;ft •KOREKI Taku ~~(CoIl. Sci., Rikkyo Univ.)
MATSUZAKI Keiichi tl' 1iJ~ ~ (Dept. Phys., Grad. Seh. Sci., Univ. Tokyo)
MINEMURA Toshiyuki
tt ~ 1T (CoIl. Sci., Rikkyo Univ.)
MIYAKE Mami =::.t J,ff ~ (Fac. Sci., Kyushu Univ.)
MIYAMA Masanori i* W 1£ *2. (Fae.Sci., Saga Univ.)
MIZUMURA Yuuki
tt ~c (Fac. Sci., Tokyo Inst. Technol.)tt f~ is (Fae. Sci., Kyushu Univ.)
MOTOMURA Shinji
NAGAKURA Masaki ~ it iE:fij (Fac. Sci., Tokyo Inst. Teehnol.)
NAGAOKA Satoshi ~ Wi] 'f! 5t: (Dept. Phys., Grad. Sch. Sci., Univ. Tokyo)
NAKADA Yoko t:p ill r; -=f (Fae. Sci., Kyoto Univ.)
NAKAMURA Shinichirou t:pftlt-a)j (CoIl. Sci., Rikkyo Univ.)
NAKANO Joe t:p ~ ~ (Cent. Nuel. Study, Univ. Tokyo)
NISHIKAWA Miyuki 1m)1[ ~ ¥ (Dept. Phys., Grad. Seh. Sci., Univ. Tokyo)
NISHIO Teiji 1m ~ t~ is (Coll. Sci., Rikkyo Univ.)
NISHIYAMA Naoki 1m W TIl fij (Fac. Sci., Niigata Univ.)
NONAKA Takamasa If t:p 19t iE (Dept. Phys., Grad. Seh. Sci., Univ. Tokyo)
NOZAWA Takeo If~ (Fac. Sci., Tokyo Inst. Technol.)
OGAWA Hiroshi IJ-.)I[ tf HRm (Fae. Sci., Tokyo Inst. Technol.)
ONISHI Kazuaki -};:. 1!§' -~;g (Dept. Phys., Grad. Seh. Sci., Univ. Tokyo)
OONISHI Tetsuya
1!§' tr ~ (Dept. Phys., Grad. Seh. Sci., Univ. Tokyo)
SAISHU Souichi ~ § ;t± (Fae. SeL, Tokyo Inst. Teehnol.)
SAITO Yoshitaka ~ Ki 7'i ~ (Dept. Phys., Grad. Sch. Sci., Univ. Tokyo)
SAKAI Hiroshi t! if i$ (ColI. Sci., Rikkyo Univ.)
SAKUMA Tai f1:~ra' ~ (Fac. Sci., Tokyo Inst. Teehnol.)
SATO Yoshiteru fiE Ki ~(Dept. Phys., Grad. Seh. Sci., Univ. Tokyo)
SATO Hiroki f1: Hi tf *2. (Fac. Sci., Kyoto Univ.)
SEKIGICHI Kimiko ~ 0 f= -=f (Dept. Phys., Grad. Sch. Sci., Univ. Tokyo)
SERATA Masaki i!t.&ill~* (CoIl. Sci., Rikkyo Univ.)
SHIBATA Masataka ~ ill ~ ~ (Fae. Sci., Kyushu Univ.)
SUZUKI Mitsuharu £1l
7t Bff (CoIl. Sci., Rikkyo Univ.)
SUZUKI Ken £1l~(Fae. Sci., Tokyo lnst. Teehnol.)

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SUZUKI Takayuki if]~ ¥(Fac. Sci., Tokyo Inst. Technol.)
TAKAHASHI Makoto ~ tit IDa (CoIl. Sci., Rikkyo Univ.)
TAKEUCHI Satoshi m: r*J ~f@ (CoIl. Sci., Rikkyo Univ.)
TANAKA Fuyuhiko 83 9J ~ ~ (Dept. Phys., Grad. Sch. Sci., Univ. Tokyo)
TANIGUCHI Etsuji ~ D tR. 9:. (Fac. Sci., Tokyo Inst. Technol.)
TANIMOTO Sayaka ~:+ ~ f! (Fac. Sci., Grad. Sch. Sci., Osaka Univ.)
TATSUKI Masayuki E8 [)it ~ ¥ (CoIl. Sci., Rikkyo Univ.)
TSUDA Masaki ?f: 83 JJ. tit (Fac. Sci., Tokyo Inst. Technol.)
TSUTSUMI Takeshi ~ IMJU ~ (Fac. Sci., Kyushu Univ.)
TUCHIDA Hideo ± 83 ":Ji:. ~ (Fac. Sci., Kyushu Univ.)
1= (Fac. Sci., Tokyo Inst. Technol.)
UCHIYAMA Yasuhito r*J ill
WATANABE Hiroshi Vi jI Jl (Fac. Sci., Kyushu Univ.)
XIAO Mei Gin J:!f ~ ~ (Grad. Sch. Sci., Univ. Tokyo)
YAKO Kentaro ~rQ]~::k~~ (Dept. Phys., Grad. Sch. Sci., Univ. Tokyo)
YAMANE Tomoki ill 1l %J:fit (Fac. Sci., Tokyo Inst. Technol.)
YOKOYAMA Go ;fl ill IMJIJ (Dept. Phys., Grad. Sch. Sci., Univ. Tokyo)
YONEDA Kenichiro *83.-~~ (Dept. Phys., Grad. Sch. Sci., Univ. Tokyo)
YOSHIDA Takufumi E 83 ~ 9:. (Dept. Phys., Grad. Sch. ScL, Univ. Tokyo)
YOSHIMI Akihiro E J! ~ i$ (Fac. ScL, Tokyo Inst. Technol.)
ZHANG Lin Feng ~ 1* UJ~ (Fac. Sci., Tokyo Inst. Technol.)m

Atomic Physics Laboratory
ANDO Kozo !:Ji jfi IMJU
IGARASHI Akinori .li+il~~1j
KANAI Yasuyuki 3Ti it 1* Z
KOJIMA Takao M. /J~ ~ ~ :1:
NAKAI Yoichi 9=J # !Wi NISHIMURA Tamio @ ft .a: ::!J5
URA Masaki
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SCHMIDT-BaCKING Horst*3
THURIEZ Sebastien *4
YAMAZAKI Yasunori ill ~~ ~ m*1-=o*1 Chief Scientist,*-*2 Senior Scientist,

AWAYA Yohko ¥ ~ ~ .:r*1
KAMBARA Tadashi 1~ mt 1£ *2
KITAJIMA Masashi ~t Jiib ~ 9:.
MARTINSON Indrek*3
NISHIDA Masami 1!§" 83 ~ ~NYSTROM Bosse*4
OYAMA Hitoshi
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URAMOTO Seiichi iffl:+ ~ -*-*3 Eminent Scientist,*4 Visiting Researcher(Visitors)
ACHLER Matthias(Inst. Kernphysik, Univ. Frankfurt, Germany)
AMUSIA Miron Ya (A. F. loffe Phys. Chern. Inst., Russia)~ iT(Grad. Sch. Arts & Sci., Univ. Tokyo)
AZUMA Toshiyuki
CHIMI Yasuhiro %I J! m"5L. (JAERI, Tokai Res. Estab.)
DePAOLA Brett D.
(Kansas State Univ., U.S.A.)FENG Xin (Dept. Phys., Univ. Ottawa, Canada)
FUJIMA Kazumi jfi rdj - ~ (Fac. Eng., Yamanashi Univ.)
FUKUDA Hiroshi f;W; 83(Sch. Administration and Informatics, Univ. Shizuoka)
HARA Shunsuke mt ~ 1r (Dept. Gen. Educ., Tsukuba CoIl. Technol.)
HINO Ken-ichi B(Dept. Appl. Phys. Chern., Univ. Electro-Commun.)HIRAYAMA Takato f ill ~ A (Dept. Phys., Gakushuin Univ.)
HULDT Sven (Lund Inst. Technol., Lund Univ., Sweden)
HUTTON Roger(Lund Inst. Technol., Lund Univ., Sweden)
ICHIMURA Atsushi rtf ft if (Inst. Space and Astr. Sci.)
ISHII Keishi 15 #- JJ! Z (Dept. Eng. Sci., Kyoto Univ.)
ISHIKAWA Norito n}ll 1* A (JAERI, Tokai Res. Estab.)
ITOH Akio fJt jfi fj( ::!J5 (Fac. Eng., Kyoto Univ.)
ITOH Yoh fJt jfi ~ (Fac. ScL, Josai Univ.)(JAERI, Tokai Res. Estab.)
IWASE Akihiro :fi liI1Ji ~KANEKO Shinichi ~.:r iJfi. (Fac. Sci., Tokyo Inst. Technol.)
KAWATSURA Kiyoshi jll 00 7i (Fac. Eng. Design, Kyoto Inst. Technol.)

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286

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KIMURA Masahiro
f1 lE. fJ{ (Kochi Univ. Technol.)
KIMURA Mineo
f1 ~ (The Sch. Allied Health Sciences, Yamaguchi Univ.)
KNUDSEN Helge(Univ. Aarhus, Denmark)
KOBAYASHI Nobuo IJ~
f~ ~(Dept. Phys., Tokyo Metrop. Univ.)
KOHARA Takao IJ~ JJ?- q:. ~ (Fac. Sci., Himeji Inst. Technol.)
KOIKE Fumihiro IJ~ it!! X tf (Sch. Med., Kitasato Univ.)
KOIZUMI Tetsuo IJ~ jjt ~ ~ (Dept. Phys., Rikkyo Univ.)
KOMAKI Ken-ichiro IJ~4t.fiJf~~~ (Grad. Sch. Arts & Sci., Univ. Tokyo)
KOWARI Kenichi IJ~ ~tl • ~ (Dept. Appl. Phys. Chern., Univ. Electro-Commun.)
KUROKI Kenro m~~(Natl. Res. Inst. Police Sci.)
KUROTA Naoshi !¥A EB ~;=G; (JAERI, Tokai Res. Estab.)
MATSUO Takashi t~ ~(Dept. Pathol., Tokyo Med. Dent. Univ.)
MATSUZAWA Michio {J}
J.m ~ (Dept. Appl. Phys. Chern., Univ. Electro-Commun.)
MITAMURA Tohru =:EBf1 mt (Fac. Eng., Himeji Inst. Technol.)
MIZOGAWA Tatsumi i#.) II 10C E (N agaoka ColI. Technol.)
MOHRI Akihiro
5f1J gJ3 tf (Fac. Integrated Human Studies, Kyoto Univ.)
MUKOYAMA Takeshi rQJ LlJ ~ (Inst. Chern. Res., Kyoto Univ.)
NAKAMURA Masato ~ f1 lE. A (ColI. Sci. Technol., Nihon Univ.)
NISHIDA Nobuhiko W 133 f~ ~ (Fac. Sci., Tokyo Inst. Technol.)
OHTANI Shunsuke~ ~ 1r (Inst. Laser Sci., Univ. Electro-Commun.)
OKAYASU Satoru ItuJ 1X ,t! (JAERI, Tokai Res. Estab.)
OKUNO Kazuhiko ~ ff *0 ~ (Dept. Phys., Tokyo Metrop. Univ.)
SAKATA Hideaki ~ EB !R: gJ3 (Fac. Sci., Tokyo Inst. Technol.)~(Fac. Sci., Kobe Univ.)
SAKURAI Makoto t;: #SATO Hiroshi ftc Hi 1{5 9:. (Fac. Sci., Ochanomizu Univ.)
SATOH Kazuhiko ~ jji ~ ~ (Fac. Sci., Tokyo Inst. Technol.)
SATOH Yukinori ftc Hi ¥ ~ (Res. Inst. Sci. Meas., Tohoku Univ.)
SEKIOKA Tsuguhisa ~ ItuJ ifflm IJ\ (Fac. Eng., Himeji Inst. Technol.)
SHIBATA Hiromi ~ EB rfi ~ (Res. Cent. Nucl. Sci., Univ. Tokyo)
SHIMA Kunihiro ~ ~~ tf (Tandem Accel. Cent., Univ. Tsukuba)
SHIMAKURA Noriyuki ~ if ~ Z (Fac. Sci., Niigata Univ.)
SOEJIMA Kouichi iU ~ 1{5 ~ (Fac. Sci., Niigata Univ.)
JjJ (Electrotech. Lab.)SUZUKI Isao ~fl
TAKAYANAGI Toshinobu ~ ~~p ~ ~ (Dept. Phys., Sophia Univ.)
TAWARA Hiroyuki ~ tf Z (Natl. Inst. Fusion Sci.)'fmj q:. (Fac. Eng., Himeji Inst. Technol.)TERASAWA Mititaka ~TO SHIMA Nobuyuki p ~~ f~ ¥ (Inst. Appl. Phys., Univ. Tsukuba)
WAKIYA Kazuyoshi Bbb ~ ~ ~ (Dept. Phys., Sophia Univ.)
WATANABE Shinichi iJi illf~ ~ (Dept. Appl. Phys. Chern., Univ. Electro-Commun.)
YAGISHITA Akira ;WP T
gJ3 (KEK)YODA Jun it( IE i~ (Natl. Res. Lab. Metrol.)
YOSHINO Masuhiro E ff ~ '51.. (Lab. Phys., Shibaura lnst. Technol.)l i gJ3(Shanghai Jiao Tong Univ., China)
ZOU Yarning §B

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(Students)
CHIBA Daisuke~~
1r (Dept. Phys., Sophia Univ.)
FAN Xiao Jun ~ ~ ,ti: (Fac. Eng., Himeji Inst. Technol.)(Dept. Phys., Rikkyo Univ.)
FUJINO Atsushi Hi ff
HORI Masaki #ill lE. *it (Dept. Phys., Grad. Sch. Sci., Univ. Tokyo)
ICHIOKA Toshiyasu m ItuJ *IJ(Grad. Sch. Arts & Sci., Univ. Tokyo)
ITO Akira W Hi If';@ (Dept. Phys., Rikkyo Univ.)
IWAI Yoshio :E # .& ~ (Grad. Sch. Arts & Sci., Univ. Tokyo)
KAMEl Takehito ~ # it {= (Dept. Phys., Sophia Univ.)
KAWAE Sotaro JIl¥I*::t:~~ (Dept. Eng. ScL, Kyoto Univ.)
KIMURA Yasuyuki
f1 $ Z (Dept. Eng. Sci., Kyoto Univ.)
MATSUSHIMA Hiroshi {J} ~ rt (Grad. Sch. Arts & Sci., Univ. Tokyo)
NAKANO Tomohide frp If 17:. ~ (Dept. Eng. Sci., Kyoto Univ.)
ONO Yasuhiro IJ~ ff ~ '51.. (Fac. Sci. Tokyo lnst. Technol.)

+

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287

SUGIYAMA Yukiko :f~ L.iJ ~ -=f (Dept. Phys., Sophia Univ.)
TAGUCHI Yoshio B3 0 ~ tl (Fac. Sci., Tokyo Inst. Technol.)
TSUCHIDA Hidetsugu ± EE
(Fac. Eng., Kyoto Univ.)
YAMASHITA Kenya L.iJ T !t ijlt (Dept. Phys., Grad. Sch. Sci, Univ. Tokyo)*.;x

Muon Science Laboratory
FU JITA Ayumi 8i B3 J;y ~ h- *1
HIGEMOTO Wataru f~
8*1
KADONO Ryosuke r~ mt .& ~KRISHN AMURTHY Vemuru *2
MATSUZAKI Teiichiro l1}~fJrrtn~~*4
NAKAMURA Satoshi N. 9J fj =rgSTRASSER Patrick*1
WIDMAN Eberhard*6*

FUKAYA Atsuko ?* ~ ~.t -=f*1
ISHIDA Katsuhiko E B3 M1 ~KOYAMA Akio /J'\ L.iJ BE til
MACRAE Roderick M. *3
NAG AMINE Kanetada 71<. ~ ~ ,'i!;,*5
PRATT Francis L.*2
WATANABE Isao Vi jl :rj; til
YAGI Eiichi )\_*4***1 Special Postdoctoral Researcher, *2 Visiting Researcher,*4 Senior Scientist, *5 Chief Scientist, *6 STA Fellow*3 Riken Fellow,(Visitors)
AKIMITSU Jun tic 7t *4! (ColI. Sci. Eng., Aoyama Gakuin Univ.)
ASAI Kichizo i~
E Ii (Univ. Electro-Commun.)DAS Prasad Tara
(Dept. Phys., State Univ. New York, Albany, U.S.A.)~ 9: (JAERI, Tokai Res. Estab.)
HASHIMOTO Masashi til
KATO Mineo 110 8i~(JAERI, Tokai Res. Estab.)
mt it (Fac. Sci., Tohoku Univ.)
KINO Yasushi
KUROSAWA Kiyoyuki !'fA ~R iN q-y (JAERI, TOkai Res. Estab.)~(Contract Researcher)
MATSUSHITA Akira lJ} T
tf (KEK)MIYAKE Yasuhiro =::t
NISHIDA Nobuhiko 1!B EE 18" ~ (Fac. Sci., Tokyo Inst. Univ.)
NISHIYAMA Kusuo 1!B L.iJ ~ ~ (KEK)
PRATT Francis Laurence(Dept. Phys., Univ. Oxford, U.K.)
SHIMOMURA Koichiro Tfjr15--~~ (KEK)
SAKAMOTO Shinichi ~ 7C !It (KEK)
TANASE Masakazu 1M l'i 1£ fo (JAERI, Tokai Res. Estab.)
TORIKAI Eiko ,~. ~ -=f (Fac. Eng., Yamanashi Univ.)

*

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(Students)
KAWAMURA Naritoshi iilT fj 1& Il (Fac. Sci., Univ. Tokyo)
ifZ ~ -=f (JKA)OOHIRA Seiko
SASAHARA Takafumi ti)Jj( ~;t (Fac. Sci. Eng., Chuo Univ.)
TOYODA Akihisa
EE ~ ~ (Fac. Sci., Univ. Tokyo)*:aMagnetic Materials Laboratory
KATSUMATA Koichi M1 X {fli. _*1
OKADA Takuya ItrrJ EE !j[ t!1*2*1 Chief Scientist,*2 Senior Scientist,

Computational Science Laboratory
EBISUZAKI Toshikazu ~ ~~ ~ _*1
SHIMIZU Tetsuya iN£t t!1 *2*-*1 Chief Scientist,

288

MATSUDA Masaaki t} EE ~ ~TATARA Gen ~.Ix.& ij*3
*3 Visiting Researcher

MIURA Hitoshi =: iii
SUMIYOSHI Kousuke*2 Special Postdoctoral Researcher

(Visitor)
HONG Shen

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(RCNP, Osaka Univ.)~*-(Student)
SUGIMOTO Satoru(RCNP, Osaka Univ.)

Inorganic Chemical Physics Laboratory
AMBE Shizuko q;: rm Wi :;.
MAEDA Kunuko lW B3 ~~ :;.
TAKAMI Michio ~ J! Ji ~ *2
*1 Visiting Researcher,

HUI Qin"£~*1
MATSUO Yukari t~~EI3~{IJ*2 Chief Scientist(Visitors)
ARAI Nobuaki )it #- 1~ ~ (Dept. Fisheries, Kyoto Univ.)
KAWAI Jun iilJ £- i~ (Dept. Metallurgy, Kyoto Univ.)(Students)
NAKAYAMA Satoshi
TONOMURA Atsuro

9=JLlJtr~~ iJ't ittm

Nuclear Chemistry Laboratory
AMBE Fumitoshi q;:!~ X ~ *1
KOBAYASHI Yoshio IJ'\ ~ ~ :5'3
*1 Chief Scientist,(Coll. Eng., Hosei Univ.)(ColI. Eng., Hosei Univ.)*-

ENOMOTO Shuichi tI:1§ _*2
TAKEMATSU Noburu 1t t~ 1$*2 Special Postdoctoral Researcher(Visitors)
AMANO Ryohei X. If .& ~ (Sch. Health Sci., Kanazawa Univ.)(Fac. Sci., Osaka Univ.)
BABA Hiroshi .~ ~TIE
CHANG Zheng?it
CHOU Ju(Changchun Inst. Appl. Chern., China)
ENDO Kazutoyo Jj: Hi(Showa ColI. Pharm. Sci.)FURUKAWA Michiaki il 111 ~ ijE3 (Fac. Sci., Nagoya Univ.)
FURUSATO Naohisa il £ ~ ~ (ColI. Sci. Eng., Aoyama Gakuin Univ.)
HIRUNUMA Rieko !RI¥~{lJrI:;' (Showa ColI. Pharm. Sci.)
ITO Nobuhiko W Hi 1$ ~ (Sch. Veter. Med. Animal Sci., Kitasato Univ.)
KATAYAMA Masayuki Jt LlJ ~ Z (Fac. Agr., Univ. Osaka Pref.)
KATAYAMA-SUGAWARA Yohko Jt LlJ i$ -T (Fac. Sci. Living, Osaka City Univ.)
iJ't ~ (CoIl. Sci. Eng., Aoyama Gakuin Univ.)
KIMURA Kan
KOJIMA Sadao IJ'\ 1i!b ~:5'3 (Nucl. Med. Cent., Aichi Medical Univ.)
MATSUMOTO Ken-ichiro t~*-~-~~ (Showa CoIl. Pharmaceutic. Sci.)
MINAI Yoshitaka ~ ~ 1t ~ (Fac. Human, Musashi Univ.)
NASU Saburo ~~ 3Ji =: ~~ (Fac. Eng. Sci., Osaka Univ.)
OHKUBO Yoshitaka "*~*&~ (Res. Reactor Inst., Kyoto Univ.)
OISHI Shigeo
E a: 1$ (Sch. Health Sci., Kanazawa Univ.)
OKAMOTO Yayoi WiJ
5$ ~ (Showa CoIl. Pharmaceutic. Sci.)
OKAMOTO Yoichi WiJ
i$ (Showa CoIl. Pharm. Sci.)OZAKI Takuo Ji€. ~~ !j[ ~~ (Fac. Sci., Univ. Tokyo)
SAITO Tadashi ~ Hi ~ (Fac. Sci., Osaka Univ.)(Res. Reactor Inst., Kyoto Univ.)
SHIBATA Seiichi ~ B3 ID;t SHINOHARA Atsushi m}]{ JJI. (Fac. Sci., Nagoya Univ.)
WANG Haifang(Peking Univ., China)
WEGINWAR Rajiv G.
(Chandrapur CoIl. Engineer., India)
YOKOTA Yuko tit B3 :m:;. (Coll. Sci. Eng., Aoyama Gakuin Univ.)
YOKOYAMA Akihiko tit LlJ 13J3 ~ (Fac. Sci., Osaka Univ.)

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289

YOSHIDA Yutaka

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(Shizuoka Inst. Sci. Technol.)***(Students)'10 (Fac. Sci., Toho Univ.)
ABE Daisuke ~iiJ ff~
7i: - (Fac. Sci., Osaka Univ.)
ARAKI Hirokazu 5iE
DAIRAKU Tomohisa~ ~D A(Fac. Sci., Nagoya Univ.)
HAYAKAWA Nobutaka !f. )111~ I!i (Showa ColI. Pharm. Sci.)IRIGUCHI Yuko A 0 fl r(Fac. Sci. Living, Osaka City Univ.)
ITOH Masahiro -@t ~ ~ 7i: (Shizuoka Inst. Sci. Technol.)
ITOH Naoya -@t ~ @: 5$ (ColI. Sci. Eng., Aoyama Gakuin Univ.)
ITOU Mayu -@t ~ ~ 83 (Sch. Veter. Med. Animal Sci., Kitasato Univ.)
MORIMOTO Shinya ~Jt ijX (Fac. Sci., Osaka Univ.)
MUKAI Kazuhiko rtD *D -;g: (Fac. Sci., Osaka Univ.)
MURASE Nobuyuki ft iJi 1$ ~ (Shizuoka Inst. Sci. Technol.)
MURATA Chihiro ft IE -+ ffi (Fac. Sci., Nagoya Univ.)
MUROYAMA Toshiharu ~ LlJ ~ i1!r (Fac. Sci., Nagoya Univ.)
NAKANISHI Kouichi $ ~ ~(Shizuoka Inst. Sci. Technol.)NISHIZAWA Satoshi ~ rR ~itr (Sch. Hygien. Sci., Kitasato Univ.)ODA Hirotaka IJ'\ IE ~.. (Fac. Sci., Nagoya Univ.)
OIKAWA Shinji "& )11 • P] (Fac. Sci., Kanazawa Univ.)
SANADA Jun Jt IE ilM] (Fac. Sci., Osaka Univ.)
SEKIGUCHI Akiko I*l 0 ~ r(ColI. Sci. Eng., Aoyama Gakuin Univ.)
SOGA Kyoko ~ ft $ r(Fac. Sci., Nagoya Univ.)
SOTOGAKU Naoki )7'\- ~ I[ m (Showa ColI. Pharm. Sci.)
TAKAHASHI Yoshio ~ trt & ~ (Fac. Sci., Univ. Tokyo)
YASHIKI Kazuhiro ~ ~ - ~ (Fac. Sci., Toho Univ.)

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Chemical Dynamics Laboratory
KIMURA Kazuie
ft - $(Visitor)
KAZAMA Shigeo

J!1.. ra' ~ it

USHIDA Kiminori±r EEl J;; m(Dept. Phys., Chuo Univ.)(Students)
HONG Wan #t ~ (Dept. Chern., Univ. Tokyo)
ITOH Noriaki -@t ~ ~ BB (Osaka Inst. Technol.)(JAERI, Tohkai)
KANEKO Junichi ~ r ;f,it!. -Cellular Physiology Laboratory
HANAOKA Fumio ;fE [1liJ )c it*l
YATAGAI Fumio ~lEffitt~*2*1 Chief Scientist,

KITAYAMA Shigeru*2 Senior Scientist(Visitors)
ANDO Koichi $: ~ ~ (N atl. Inst. Radiol. Sci.)
FUKUMURA Akifumi fM ft ~.se (Natl. Inst. Radiol. Sci.)
FURUSAWA Yoshiya r:!l?* 1*: ill (Natl. Inst. Radiol. Sci.)
HAM A Yoshimasa ~ ~ ~ (Sci. Eng. Res. Lab., Waseda Univ.)
HOSHINO Kazuo £ mf - it (Natl. Inst. Radiol. Sci.)IIZUKA Masayuki ~ ;I:~ 1£;;t (Natl. Inst. Radiol. Sci.)
ITO Hisao -@t~ ~(Sch. Med., Chiba Univ.)(Natl. Inst. Radiol. Sci.)
ITOH Hiroko -@t ~ i1!r
ITSUKAICHI Hiromi .Ii B U' is ch- (Natl. Inst. Radiol. Sci.)
KAN AI Tatsuaki ~ # Jt ~ (N atl. Inst. Radiol. Sci.)
KASAl Kiyomi j£ # it ~ (N at I. Inst. Radiol. Sci.)

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290

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KAWACHI Kiyomitsu 7~ I*J 1ff 7t (Natl. lnst. Radiol. Sci.)
5C IE ~ (Natl. lnst. Radiol. Sci.)
KIMOTO Masafumi~ ~(JAERl, Takasaki Rad. Chern. Res. Estab.)
KOBAYASHI Yasuhiko IJ'\
KOHNO Toshiyuki 7~ tf ~ Z (Natl. lnst. Radiol. Sci.)
KOIKE Sachiko IJ'\ 1t!! ~.:r (Natl. lnst. Radiol. Sci.)
KOJIMA Eiichi IJ'\ ~(Natl. lust. Radiol. Sci.)
KUBOTA Nobuo
B3 1r ~ (Pac. Med., Yokohama City Univ.)It. (Natl. lnst. Radiol. Sci.)
LI Ryonpha
MATSUFUJI Naruhiro t~ ~ nX: ~J.,. (Nat!. lnst. Radiol. Sci.)(Natl. Inst. Radiol. Sci.)MINOHARA Shinichi ~ J]{ {$ MIYAHARA Nobuyuki g J]{ {~~ (Natl. Inst. Radiol. Sci.)
MURAISO Chidori ft 1i! ~ 1* (Natl. Inst. Radiol. Sci.)
MURAKAMI Masahiro ft.L IE~.L. (N atl. Inst. Radiol. Sci.)
OHARA Hiroshi
J]{~.L.
(Dept. Gen. Cult., Okayama Univ.)
OKUMURA Toshiyuki J! ft ffJ. Z (Fac. Med., Univ. Tsukuba)
SAITO Mizuho 1f Hi fffff f.! (N at I. Inst. Radiol. Sci.)
SASAKI Hiroshi 11:4* ~.L. (Fac. Med., Kyushu Univ.)
SHIKAZONO Naoya J.l ~~(JAERI, Takasaki Rad. Chern. Res. Estab.)
SOGA Fuminori ~?Jt X '§" (Inst. Nucl. Study, Univ. Tokyo)
SUDO Michio ~J{Hi~~a (Natl. Inst. Radiol. Sci.)TAGUCHI Yasuko ill 0 ~.:r (Natl. lnst. Radiol. Sci.)(RI Cent., Nagasaki Univ.)
TAKATUJI Toshihiro ~ it ~TANAKA Atsushi ill ~(JAERI, Takasaki Rad. Chern. Res. Estab.)
TANAKA Kaoru ill ~ •(Natl. lnst. Radiol. Sci.)TATSUZAKI Hideo rz. ~~ !i:. ~ (Pac. Med., Univ. Tsukuba)
TOMURA Hiromi 9i- ft ¥11 ~ (Natl. lnst. Radiol. Sci.)
TSUBOI Atsushi i'f #~(Natl. lnst. Radiol. Sci.)
TSUBOUCHI Susumu i'f I*J J1§ (Suzuka Med. Technol. Univ.)
WATANABE Masami Vi ill. lE C. (Pac. Pharm., Nagasaki Univ.)(Natl. Saitama Hospital)
YAMASHITA Shoji LiJ r J§

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Plant Functions Laboratory
ABE Tomoko ~ilJ ~~ ~ .:r
MATSUYAMA Tomoki t,t} LiJ ~ :flt*2
YOSHIDA Shigeo "'5 83 r.t. 5'5 *3*1 Postdoctoral Researcher,

BAE Chang-Hyu ~TAKAHASHI Yoshiko*2 Special Postdoctoral Researcher,J§ ;1*-*1~ tit {t.:r

*3 Chief Scientist(Visitors)!if (Dep. Biosci., NAIST)HASHIMOTO Takashi m
SATO Fumihiko 11: Hi X ~ (Dep. Agr. Chern., Kyoto Univ.)
SATO Shinobu 11: Hi !d, (Inst. Bio. Sci., Tsukuba Univ.)
If - (Suntory Ltd.)SUZUKI Kenichi jii**:E # * BJt
is(Students)
IWAI Hiroaki(Inst. Bio. Sci., Tsukuba Univ.)(Weed Sci. Cent., Utsunomiya Univ.)
KUMATA Shuji ~~ B3 f;j
TAKAHASHI Hideki ~ {l !i:.:fir (ColI. Agr. & Vet. Med., Nihon Univ.)

Microbial Toxicology Laboratory
ARIE Tsutomu ~11rI

YAMAGUCHllsamu

ill 0

~*

* Chief Scientist(Visitors)
GOUTHU Satyanarayana
291

NOSE Yasuhiro ~~ ~ ~ •SHIN ONAGA Taeko iii 71<. ~j; r
WATANABE Tadakazu ill ii~ ,'i!', -Safety Center
HARASAWA Kaoru )Jjt ¥.R •MATSUZAWA Yasuhide t,t} ¥.R 1;; ~NAKANISHI Noriyoshi $ W ff.2. %*UWAMINO Yoshitomo J: tit ~ ~Jj
YOSHIKI Hajime 15 ~ •(Agro-Kanesho Co., Ltd.)KAGAYA Satoru nD~.@: f~
MIYAGAWA Makoto '8 JII • ~SHINOHARA Shigemi iii)Jjt:a:
YAMAN AKA Akira LlI 1tfJ II)'te.

* Head*Surface Characterization Center
IWAKI Masaya -E
1E ~*NAKAO Aiko

$ ~ ~rSUZUKI Makoto

jii* HeadRadioisotope Technology Division
GORDON Alasdair*1
YATAGAI Fumio ~83jt:t~*3*1 STA Fellow,*2 Special Postdoctoral Researcher,

*

ff:*2

*3 Head(Visitors)
FU JIE Akio ni!i! tl (Furuuchi Chemicals)
KAGAWA Yasuhiro W}lI. i1!i (Toray Res. Cent. Inc.)KASE Youko~(Natl. Inst. Radiol. Sci.)
MAEZAWA Hiroshi frJ
tf (Fac. Med., Tokai Univ.)
OGURA Koichi IJ'\ it fit: (ColI. Ind. Technol., Nihon Univ.)
SUZUKI Masao iii~ 1$(Fac. Pharm., Nagasaki Univ.)

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(Student)
SAITO Tomohiro

292

i'

~ ni ~ JJ:(Fac. Life Sci., Tokyo Univ. Pharmacy & Life Sci.)

AUTHOR INDEXABE Ryo[\II1$?t

5
148

CHOU Ju

JEJt" 72,77
AIHARA Toshimitsu IBKflJ:7t
3

ADACHI Minoru$***

AKAGI Hiroyasu
AKIKAWA Hisashi

52, 53

fjcs'fg"JE

ALONSO Jose R.
AMANO Ryohei~ff .& ~AMBE Fumitoshi*ffi5xfDt~

tl]

67, 158

97

133, 134, 135

CHULKOV Leonid

79

CORTINA Dolores

79

CZAJKOWSKI Serge

5

fjcJIIHiit-AKIYOSHI Hiromichi~J!.~t..

CHIMI Yasuhiro~iiJ$~r

ABE Tomoko

DELBAR Therry

78

10
~it

DINH DANG Nguyen~i19, 20, 27, 28, 29

126, 127~9, 50, 51
EATON Gordon H.
EGUCHI-KASAI Kiyomi tID (3£:jf) ~~119, 120, 121, 122, 123,

ENDO Kazutoyo

124, 125, 126, 127, 128,

ENOMOTO Shuichi

70

itHi*D~150

130,_)31, 13;~ .~___*I*~-//' 123, 126, 127, 128, 129',< '

129, 130, 131, 132, 133,

*ffi5ftr

AMBE Shizuko** M

ANDO Atsushi
ANDO Kozo*Hilill]=

135, 137, 138, 139,~,

141

141
EN'YO Hideto~lJ-~ A52, 53, 170, 172, 173
99131, 132, 133, 134, 135, 136,

FAN Xiao-J un

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1IJt~

137, 138, 139, 140, 141, 145,

FEINAUER Adolf

119

146

FORSTER Andreas

78

127

FRANCE III Ralph

10

10, 64, 67, 68, 69, 75, 162

FUJIE Akio

iiiiIliitit

151

iii#~zFU JII Masayuki

169iiii'*=

w:jf ~ 64, 65, 69, 71, 72, 73, 74, 76, 121
AOKI Yuka w*Ef3w
165253, 254
ARAKAWA Takesi 5iEJ II ~it

FUJISAWA Eiji
FUJISHIMA Shiro

ARAKI Hirokazu
ARIE Tsutomu ;ffiI 1J

iiiEE=eB 5, 182, 183
253, 254
FUJITA Shin iiiEE *iFUJITA Tatsuru nlEE Jl
158

AOI Norim**-

ARIMA Akito

142
145, 146;ffj{fl~

ARIGA Takehiro;ff.~e,ijA

167

AWAGA Kunio~iiJ 1ltj{~~~

AWAYA Yohko~~~r

BAKALOVA K.

~~

FUKAO Tetsuhiro

i*~'fg"*

66,70

106

FUKUDA Mitsunori

111
142
148

1iEE:7tJIIJi 66,70
FUKUDA Naoki 1iEEiiW
65, 67, 71, 72, 73, 74, 76
66,70,72,77,177,178
FUKUDA Shigekazu 1iEEaFUKUDA Tomokazu m EE ~*D
65
1igg~M1FUKUNISHI Nobuhisa

203

52, 192, 235, 237, 239, 246

BAUMANN Thomas
BLANK Bertrum

15, 147, 151, 200,
202, 245

FUKUSAKA Shoichi

89. BANDYOPADHYAY Arup

BOCHKAREV Oleg

113

62, 63-oi'13:HH.

149

10, 64, 78
108

78, 79G EISSEL Hans

15-it-/W;- 177, 178
1i*Jl:t: 169

79

GOHSHI Yoichi

81

GOKA Tateo
GONO Yasuyuki
GOTO Akira

1i~~~-

67

FURUSAWA Yoshiya
GEIBEL Christoph78

BUENKER Robert J.

FULOP Zsolt
GAl Moshe

78
78

BLUNDELL Stephen J.
BOUE Frederic

72, 7789

BAKALOV Dimitre
BATYGIN Yuri

64, 67, 69, 75

94, 157*

BABA Hiroshi .~~BAE Chang-Hyu ~216, 218
FUJITA Jiroiii~~W*±~:7t

ASAMITSU Atsushi

52,53
iii~9:M
205, 206, 208, 210, 214,

FUJIWARA Hideki

17, 19, 20, 26, 29

1l!! fjj:-eB

ASAHI Koichiro~

123, 124, 125, 128, 129; 130,91, 92, 93, 94*Hi~lii

ANDO Yoshiaki

130, 131, 132, 133, 134,

134, 135, 138, 139, 140,

~UUnZ

1&Hi

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56, 57, 58
5, 143, 181, 182, 185, 187,

CEDERWALL Bo

56

CHIBA Daisuke

T;J~*fr

95

189, 191, 192, 194, 196, 198,

CHIBA Toshiya

T~flJ~

3, 191, 192, 198

200, 203, 205, 206, 208, 210,i

212, 214, 216, 218, 220, 222,IDEGUCHI Eiji

#1:i1 D5R?fi

56, 57, 58, 73, 74, 76

224

IDESAWA ErikolfHR~:f1.T

161

44,52,53,54,55, 170, 173
GOTO Yuji f&Xitt=
145, 146
GOUTHU Satyanarayana

IEKI Kazuo *jj!.UD~
64
IGARASHI Akinori 11t-Jiijl3~1j

G ROSSE Eckart

7t!!1E tf 98
IKEGAMI Kumio 7t!!L:fL:=5'3
5, 167, 187, 205, 208,

GU Jian-Ping

78

----

81

HAHN Kevin Inskik

10, 64, 67, 69~~,IJ{~HAMANAKA Hiromi
HANAOKA Fumio

1tltliJxtt

HARASAWA Kaoru

mOR.

176
151
256

ffi"::s-msift tt

HASEBE Hiroo

87

IKEDA Hiroshi

3210,224

IKEZAWA Eiji

7t!!7R~=3, 192IMAI Ken'ichi

4-#~-52, 53, 170, 172

IMAIDA Isamu

4-#lEfJt11:*
4-tt *tt

169

IMAMURA Mineo

59

HASEGAWA Ken-ichi

ffi":~J1IIf-

176.!MfiE-Naohito ~ - 5, 167, 191, 227

HASHIMOTO Masa-aki~*iE]jI40

ISHIBASHI Ryochi

HASHIMOTO Masashi~*!Jl9:49, 50, 51

u.T ~

149

HASHIZUME Akira:fii;J1\ g~

179

49, 50, 51, 113
ISHIDA Katsuhiko ulEM1~
ISHIDA Satoru u IE ,t!
60, 61, 62, 63

HATANAKA Kichiji

iIB~Eifi

52, 61,62

ISHIDA Takayuki

HAYAKAWA Kazuo

If.JII-~

120,121

ISHIE Masami

HAYAKAWA Shinjiro

If.J1I'll=e~

HAYASHIGAKI Arata#m: $JT46
i1[W 44,52,53,54,55,170,172,

HAYASHI Naoki#

HAYES William

113

177,178u IE MHr112u¥I~itJ;~

126

uJJl{iE~

ISHIHARA Masayasu

10, 52, 53, 56, 57, 58,
64, 65, 66, 67, 68, 69,
71, 72, 73, 74, 75, 76,
77, 170, 171, 172

173
78,79
HELLSTROM Margareta
HEMMI Masatake ~~i&m:
3, 191, 192~*

HIGEMOTO Wataru

105, 106, 110

Q

HIGURASHI Yoshihide B ~:ff*
HILLEBRANDT Wolfgang
35

67

B!f~-

82

HIRAI Masaaki-"¥#iE~10, 64, 67, 69

HIRAI Masanori-"¥# iEm:

44, 45HIRATA Daisy-"¥!f~~

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