UTTAC-69, 2001

ANNUAL REPORT
April 1,2000 – March 31, 2001

TANDEM ACCELERATOR CENTER
UNIVERSITY OF TSUKUBA

http://www.tac.tsukuba.ac.jp/

PREFACE
This volume describes research activities in UTTAC during the period from April 2000 to March
2001. The operation of the 12 UD Pelletron tandem accelerator was interrupted in August 2000
because of the trouble of corona points mounted on the first tube section on the low energy end. Afterthe repair of the corona points, the tandem accelerator was continuously operated until the end of
February 2001. A total beam time used for experiments was 2783 hours. The tandetron accelerator wasused for experiments on solid state physics and PIXE analysis of some biological materials.
The developments of experimental instruments initiated in the last year were continued on a proton
polarimeter, a TOF detector for atomic clusters at low velocities, a long focal-plane position-sensitive
detector and an ECR ion source equipped with a liquid-helium-free superconducting solenoid.
Nuclear reactions with polarized deuterons, an analysis of the p+28Si total-reaction cross section atenergies around the 28Si(p,n) threshold energy, a precise measurement of proton-proton elastic scatteringcross section at energies around 20 MeV are included in this volume as progress reports. An experiment on
the transient magnetic field using polarized protons was also performed. Nuclear structure physics bymeans of in-beam gamma ray spectroscopy and some activities in high-energy nuclear physics aiming
at the search for quark-gluon plasma are also described in this annual report.
Ion-induced secondary electron spectroscopy, atomic cluster physics, the electronic states of 3dtransition-metal oxides by NMR and Moessbauer experiments made a steady advance. Some new
results are reported on the investigation of an active center produced by the heavy ion bombardment ofsilica glass and on the diffusion of deuterons implanted in Ta and Cu.
The quantitative trace element analysis of fluid inclusions in natural quartz was carried out bymeans of PIXE. It turned out that inclusions in the quartz collected from Kwahage quartz veins in
Nagano prefecture in Japan contained transition metal elements at several 100-1000 µg / g. A new
project of hydrogen analysis was approved in the last year. To construct a new beam line for thisproject, the heavy-ion post accelerator and the Ge detector array for gamma-ray spectroscopy wereshut down. A method of the preparation and calibration of a standard hydrogen-bearing target wasdeveloped. The measurements of 36Cl with AMS techniques were performed for samples that weretaken at several places near the nuclear fuel processing facility JCO after the critical nuclear accident
in two years ago.
A symposium was held on 12 and 13 in December 2000 as the 25th anniversary of thecommencement of experiments with 12 UD Pelletron. Many fruitful discussions were made on nuclear
physics, solid state physics, PIXE, AMS, and some other topics related to tandem accelerators.

Kohei Furuno-i-CONTENTS
1. ACCELERATOR AND EXPERIMENTAL FACILITIES
1.1

Accelerator operation........................................................................................................1

1.2

Construction of a system for hydrogen analysis ...............................................................5

1.3

Development of a proton polarimeter using a liquid helium target and armeasurement of the polarizations of the 52Cr( d , p )53Cr reaction ..................................9
1.4

Development of oven type cluster ion source.................................................................11

2. NUCLEAR PHYSICS ----- Experiment
2.1 Polarization transfer in the 2H(d,p)3H reaction at θ=0° at very low energies.................15
2.2

r

r

Analyzing powers for the ( d ,α )and ( p ,α) reactions in the continuum at
an incident energy of 20 MeV .......................................................................................17

2.3

r

Analyzing power T20 for the 6Li ( d ,α) 4He reaction at an incident energy of 90 keV ..19

2.4 Measurement of proton total reaction cross sections for natSi
near the 28Si(p,n) threshold energy (II) ..........................................................................21
2.5 Toward proton-proton scattering at forward angles (III) ................................................24
2.6 Measurement of the proton spectrum in deuteron break-up reaction .............................25
2.7

Yrare bands in 119Xe .......................................................................................................27

2.8 Band structures in the doubly odd nucleus 130Cs ............................................................30
2.9

Level structure of 118I......................................................................................................35

2.10

Preliminary measurement of the g-factor of the second excited state in 165Ho.............38

2.11 Measurements of fusion cross sections in the reactions of 82Se+138Ba and 82Se+134Ba.39
2.12 Measurement of transient magnetic field by using polarized proton ions………….....43

3. ATOMIC AND SOLID STATE PHYSICS, AND CLUSTER SCIENCE
3.1

Carbon KVV Auger electron emission from HOPG bombarded by fast protons ...........46

3.2

Ion-induced electron emission from damaged Si crystals ..............................................49

3.3

New family member of active center created by multi-MeV ion bombardmentof silica glass..................................................................................................................51

3.4

Foil thickness for ions attaining charge equilibrium.......................................................56

3.5

Difference of the diffusion and trapping of the implanted deuterons
in metals between the single crystal and poly-crystal....................................................59

3.6

Formation of transition metal cluster silicides on gas phase reactions ...........................60

3.7 Measurement of large-sized Cu cluster ions by using a quadrupole deflector
and a TOF mass spectrometer........................................................................................62
3.8 The effect of a biased electrode on operation of ECR ion source using
liquid He free superconducting solenoid coils...............................................................64- ii -

3.9

Production of highly charged Xe ions from liquid-He-free superconducting
electron cyclotron resonance ion source (SHIVA).........................................................67

3.10 Physical process of cluster formation in sputtering of various metals
with 6 keV Xe atoms....................................................................................................70
3.11 Metal cluster growth in a gas aggregation cell combined with a magnetron sputter ....77
3.12 The science of 3d transition-metal oxide system ..........................................................80
3.13 Mössbauer study of some granular magnetic materials................................................84

4. ION BEAM APPLICATION
4.1 Quantitative trace element analyses of single fluid inclusions
in hydrothermal quartz by PIXE ....................................................................................87
4.2 Permeability modification of rat intestine induced by inflammation
shown with PIXE measurement.....................................................................................91
4.3

A proposed method of the determination of the number of hydrogen atoms
in a standard target for hydrogen analysis .....................................................................96

4.4

Preparation of standard targets for hydrogen analysis ..................................................100

4.5 Status of Tsukuba AMS system ....................................................................................103
4.6

AMS 36Cl measurements of KEK concrete shielding blocks........................................105

4.7 AMS 36Cl measurement of JCO soil samples ...............................................................107

5. LIST OF PUBLICATIONS ............................................................................109
6. THESES ................................................................................................................114
7. SEMINARS..........................................................................................................115
8. SYMPOSIUM .....................................................................................................117
9. LIST OF PERSONNEL...................................................................................119- iii -

1.1

Accelerator operation

K. Sasa, S. Ishii, H. Kimura, H. Oshima, Y. Tajima, T. Takahashi, Y. Yamato,
T. Katabuchi, T. Komatsubara, K. Shima and K. Furuno
The periodic maintenance per year was finished on March 29 in 2000. After the voltage conditioning for
two weeks, we provided beams for experiments from April 17. The total operating time and theexperimental beam time were 3480.5 and 2782.9 hours respectively, for the period from April in 2000 to
March in 2001. Each time recorded an increase of about 20 % as compared with that in the last year. Fig.1
shows the distribution of operation hours every month. The beam time at various terminal voltages isshown in Fig.2. Fig.3 presents the summary of accelerated ions and fractions of their beam time for three
ion sources. Fig.4 shows the percentage of experimental beam times for research fields.

500
450
400
350
300
250
200
150
100
50
0

Fig.1

2000
Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

2001
Jan

Feb

Mar

Accelerator operation hours per month from April in 2000 to March in 2001.

11 MV
10 MV
9 MV
8 MV
7 MV
6 MV
5 MV
4 MV
3 MV
2 MV
0

100

200

300

400

500

600

700

Beam Hours

Fig.2

Beam time summed up every 1 MV of terminal voltages.

-1-

AMS
Ion Source

97Mo
0.2
36Cl
1.3
4He
0.4

129I
0.1
127I
0.7

35Cl
12C 3.4
1.4
1H
25.5%

2H
1.2

SputterIon Source

Polarized
Ion Source

1H
23.7

2H
8.3

7Li
1.9

127I
0.4
10B
5.8

32S
10.0
79Br
0.1

64Cu
0.7

28Si
0.2

19F
7.7

11B
1.3

16O
2.7
13C
2.0

Fig.3

12C
0.8

Accelerated ions and fractions of their beam time for three ion sources.
Accelerator Science
0.4%
Nuclear Physics(nuclear reaction)
20.0%

Atomic and Solid
State Physics
6.7%
Accelerator Mass
Spectrometry
6.8%

Earth Science
18.1%

Nuclear Physics(polarization)
27.9%
Nuclear Physics(nuclear spectroscopy)
20.1%

Fig.4

Percentage of experimental beam times for research fields.

The beam time at the terminal voltage of 11 MV was about twice as large as that in the last year. There
are two groups in distribution of the beam time. Almost all the high voltages in the range from 7 to 11 MV
were used for nuclear physics. Low terminal voltages in the range from 2 to 5 MV were used for the ion
beam analysis in earth science.
The operation of the 12UD tandem accelerator was very stable until July in 2000. In August, however,
the terminal voltage became gradually unstable. We observed extremely large fluctuation of corona
currents and X-ray bursts in the case of the first and second units alive. It suggested that the problem
occurred in the first or the second unit on the low energy side. We opened the accelerator tank on August
21. The corona points on the first accelerating tube section hung down as shown in Fig.5 (a). This
problem was just the same as that in its position and phenomenon occurred in July of 1999 [1]. The
accelerating electrodes were electrically shorted outside the tube two by two in order to reduce the voltage
gradient at the entrance of the accelerating tube for small magnification as a converging lens. For this

-2-

(a)

(b)

Old shorting wire

Fig.5

New shorting wire

Shorting wires on the first accelerating tube. (a): Hanging corona points before the repair.

Shorting wires directly were connected to corona needle plates. (b): Shorting wires were modified tocopper plates and mounted on the opposite side of the corona points in the position.

Fig.6

A plumb was hung down from the upper

Fig.7

A photograph

of

the

chain-motor

chain sheave to the bottom of the tank. The

coupling. It is made of Hytrel developed by DU

position of the lower sheave was adjusted with

PONT-TORAY Co., Ltd. We selected it in order torespect to the position of the plumb.

insulate between the motor and the sheave.

purpose, a copper wire was put between the socket for the corona points on the spark-gap ring of theelectrode. In addition to the difficulty for obtaining stable fit in this geometry, the thread became worn sothat the connecting force was not strong enough. We separated the mount of shorting wires from that ofcorona points. Copper plates instead of wires were used to short electrodes with new setscrews. The
copper plates have a stable fit on the socket and the screw holder. Fig.5 (b) shows the new shorting
method for the first accelerating tube section.
As regards other troubles, the power supply for switching magnet in the second target room was broken
on August 1. We used the power supply of the first target room temporarily until March of 2001, and thena new power supply produced by DANFYSIK Co., Ltd. was installed.
There is a serious problem in our SF6 gas system. The compressor is very old and an appreciable leak-3-

occurs at the connecting rod. We lost SF6 gas by 656 kg in the operation of the gas handling system twelve
times year of 2000. Four times of them were carried out for the maintenance. The others were performed
for AMS experiments. In our experience, stable corona currents along the accelerating tube in particular
are necessary to obtain reasonable reproduction of the data.
The scheduled maintenance in the spring of 2001 was started from the March 1. The major works of thismaintenance were as follows. All corona points were replaced along the column and the accelerating tube.
Stripper foils in A and B foil changers were also replaced by new foils. Before the start of this scheduled
maintenance, there was a tendency to increase the fluctuation of the charging current when theacceleration of beams was unstable in the slit control mode. It was supposed that the fluttering of the chain
sheave during the rotation and the snaking of the chain towards the terminal might cause the fluctuation of
the charging current. We carefully adjusted the position and alignment of sheaves by hanging down aplumb from the sheave in the terminal (Fig.6). The old ball bearings of the sheaves were replaced. The
insulating coupler made of Hytrel, which was supplied by DU PONT-TORAY Co., Ltd. was inserted
between the chain motor and the sheave (Fig.7). The resistance between the sheave and the ground wasincreased to a value larger than 2000 MΩ. An overhaul was made of the thin plate attached to the sheave(contact band) to obtain good contact with pellets. Finally, we adjusted gaps between the chain andstabilizing wheels (idler wheels) in such a way that the snaking of the chain became as small as possible.
After these works, the fluctuation of the charging current disappeared as long as we observed the current
on the analog current meter by the eyes.
In the period of this maintenance, some modifications on beam lines were carried out. This was
motivated by the start of a new project of micro-beam hydrogen analysis with 19F and 15N ions in one hand.
Another motivation was that the walk of the focus in the first target room produced by the quadrupole
doublet in front of the switching magnet was large. It was because of the misalignment of the beam
emerging from the image slit of the beam analyzer from the axis of the quadrupole doublet. To carry out
the new project, the heavy-ion post accelerator was shut down. The post buncher installed about 1 m
upstream of the quadrupole doublet was removed. This part of the beam line was modified to a simple
beam line equipped with an ion pump. The work of the focus produced by the quadrupole doublet was
minimized by the displacement of the opening in the object slit of the beam-analyzing magnet by 1 mmfrom the vertical line of the accelerator. The opening position was adjusted by observing the movement offocus on a ZnS plate as the excitation current of the magnet was increased. This displacement would be
due to the fact that the bending plane of the beam-analyzing magnet is not vertical exactly.
The total operating time of the tandetron accelerator was 524 hours for the period of last year. We haveused this accelerator for PIXE, RBS, secondary electron spectroscopy, detector tests and preliminary
experiments for investigations using the 12UD tandem accelerator. At present, we have been constructing
a new micro-beam line for PIXE and/or RBS analyses.
[References][1] K. Sasa et al. UTTAC-68 (1999) 1.

-4-

1.2

Construction of a system for hydrogen analysis

K. Sasa, K. Furuno, H. Oshima, Y. Yamato, T. Takahashi and K. Shima
The hydrogen analysis of minerals and rocks by means of the resonant nuclear reaction 1H(19F, αγ)16O or
1

H(15N, αγ)12C was started as a new project in 2000. One of the objectives is the measurement of theconcentration of water in fluid inclusions in minerals. Since the size of the fluid inclusions in the range
from 100 to 30 µm or less, the incident 19F or 15N beam must be focused on mineral samples in an area aslarge as those of fluid inclusions. In addition to the transverse confinement of the area of beam irradiation,
the measurement of depth profile is necessary for three-dimensional mapping of water in fluid inclusions.
We have developed a new beam line dedicated to the hydrogen analysis in the 0° beam course in the firsttarget room. This report describes the design and a preliminary test experiment to estimate beam currents
through a narrow slit.
[1] Design of the beam line.
Fig.1 shows a schematic layout of the new beam line. It consists of a beam defining aperture (first slit), a
collimating aperture (second slit), a diaphragm (third slit) and a quadrupole lens. The length of the beamline is limited within 14.7 m by walls of the target room. Taking a passage and working space behind thetarget chamber, we determined the distance from the beam exit wall to the target to be 11 m. The first slit
is placed at a position of 0.3 m upstream from the wall of the switching magnet room. The resultant
distance between the 1st slit and the target is 12.8 m. The distance from the exit of the quadrupole lens to
the target is chosen to be 0.35 m from a tentative design of the target chamber. Other distances arepresented in Fig.1.
The beam emerging from the image slit of the beam analyzing magnet is once focused onto the first slit
through 0° port of the switching magnet with the aid of the quadrupole doublet (QS) and a steering magnet
First Target RoomAnalyzer Magnet Room
2400

3670

2795

12800
300

1500

1000

500

Steerer

1140

350

Steerer
Analyze
Magnet

Image
Slit

QS
ST6
Switching First
Magnetic Quadrupole Magnet Slit Wall
MagnetSteerer

2nd
Slit

Microbeam line system

Target
3rd Russian
Slit Quadruplet

Russian Quadrupole

ObjectPoint

Steering Magnet

Switching Magnet

Power Supply

Quadrupole Magnet

Control Computer
Platform: Windows2000
Network: 100BASE-TX TCP/IP

Steering Magnet
Analyzing Magnet

Ion Species & Energy

Input

Power Supply

Community System

Fig.1

A schematic layout of the beam line and the control system.

-5-

Fig.2A photograph of the Russian quadruplet and the specifications.

(ST6). The beam is further collimated by the second slit placed 2.8 m apart from the first slit. An
adjustable diaphragm is prepared to limit the divergence of the beam. The beam is finally focused on thetarget by means of a Russian Quadruplet[1]. This quadrupole lens was constructed by remodeling two
quadrupole doublets available in our laboratory. The space between two poles was 200 mm in the olddoublets, but it turned out from a calculation that a narrower space was advantageous to obtain smaller
beam spot sizes on the target. On the basis of this calculation, the space was modified to be 180 mm,
which was narrowest space limited by the mechanical structure of the old quadrupole magnet. The
principal specifications are described in Fig. 2.
Beam optics calculations were carried out with the computer program TRACE-3D [2]. A typical exampleof the envelope of 19F4+ ions at an energy of 30 MeV is displayed in Fig.3. The calculation is made theassumptions that the diameter of the first slit is 0.71 mm; the maximum angles of the beam are 0.71 mradin both vertical and horizontal planes; the energy spread of the beam is 12.5 keV. On these conditions, thediameter of the beam spot on target is 59.2 µm, while the angles are 8.45 mrad in both planes. This result
implies that a reduction factor of 0.084 could be expected for the beam diameter. The maximum transverse
excursion of the beam occurs in the vertical plane. The value is about 11 mm. It is sufficiently smaller than
the inner radius of 17.5 mm in the vacuum pipe of the Russian quadruplet.
The depth profile of hydrogen atoms can be obtained from the measurement of the yield of γ rays as afunction of the incident beam energy. The principal composition in most of the minerals and rocks is SiO2.
The width of the 16.44 MeV resonance is reported to be 83.8 keV in the laboratory frame [3]. The
First slit position

Target position

19F4+ beam

30 MeV (∆E=12.5 keV)
50 nA

Russian quadruplet
QM1,4 : 0.610 kG/cm
QM2,3 : 1.469 kG/cm

Emittans 0.25π mm mrad
Slit diameter x=y=0.71 mm
Angle of the beam θx=θ y=0.71 mrad

Fig.3

Beam spot diameter x=y=59.2 µm
Angle of the beam θx=θ y=8.45 mrad

A calculated beam envelope in horizontal and vertical planes of the proposed 19F4+ ionsat 30 MeV. Emittance diagrams at the first slit and the target are also displayed.

-6-thickness corresponding to the width of 83.8 keV is calculated to be 0.03 µm with the stopping power of19

F ions in SiO2. This value is much smaller than a typical size of fluid inclusions. Although it depends on

research subjects how many data points are required for depth profiling of a certain fluid inclusion, theincident energy should be changed, in general, over several tens of steps. The design and construction of
an automatic focusing system, therefore, are in progress. The concept is presented in Fig.1. Power supplies
for the beam analyzing magnet, quadrupole magnets and steering magnets are controlled by a personal
computer equipped with Windows 2000 as its operating system.
[2] Test experiments.
As described in the preceding section, the diameter of the first slit must be smaller than 0.6 mm to obtainbeam spot sizes on target smaller than 50 µm. It is obvious that the beam current seriously decreases after
the first slit. We performed a test of beam transmission for 19F4+ and 19F5+ beams to estimate practicallyobtainable beam currents. Experimental setup is shown in Fig.4. The Faraday cups FC1 and FC2 aremounted on the object and image position of the injection magnet. FC2 measures negative beam currents
injected into the tandem accelerator. FC3 is located at the exit of the accelerator, while FC4 is placed in
front of the beam analyzing magnet. FC5 is installed just after the image slit of the beam analyzing magnet,
and measures the analyzed beam current.
A tentative slit was placed at a distance further than the design position of the first slit by 4.8 m. Three
apertures of 0.6, 1 and 2 mm in diameter were prepared for the tentative slit. The surfaces of theseapertures were covered with ZnS phosphor to observe the beam spot with video camera. Beam currents
after the tentative slit were measured with the same type Faraday cup as FC5. The energies of beams were
20 MeV for 19F4+ ions, and 24 MeV for 19F5+ ions, respectively. The experimental results are summarizedin Table 1.
The beam currents observed with the aperture of 0.6 mm in diameter were 2.5 enA for 20 MeV 19F4+ ions,and 6.3 enA for 24 MeV 19F5+ ions. The beam spot was 4 mm wide and 8 mm high. This size of the beam
Slit1
Ion Source
CaF 2 Target

Slit2

FC1
FC2

F-

TandemFC3
Object Slit

Σ F +qFC4

Tentative Slit
F 4+ or F5+

Image Slit

Fig.4

FC5
F 4+ or F5+

FC-Target

A schematic diagram for the measurement of transmission of 19F beams.

-7-

spot is roughly in agreement with the opening of the image slit of the beam analyzing magnet (2 mm times
3 mm) multiplied by the magnification of the quadrupole doublet (QS) in front of the switching magnet. If
we move the first slit to the design position, the magnification of QS became almost unity. The ratio ofareas of the aperture of 0.4 mm in diameter to the beam spot of 2 mm times 3 mm is approximately 0.02.
Thus an expected beam current through the aperture of 0.4 mm in diameter is calculated to be 2 enA for ananalyzed current of 100 nA at FC5, if we make a very crude assumption that the beam intensity has
uniform distribution over the area of 2 mm times 3 mm.
The experimental results given in Table 1 indicates that about 1 µA of negative beam currents arenecessary to obtain 100 enA of analyzed beam current at FC5. The operation of the tandem accelerator
was stable without problems like electron loading for injection of negative beam of 1 µA or more. Short
lifetimes of stripper foils remains as a practical problem in such an acceleration of low-energy heavy-ion
beams with high intensity as the present application.
Table 1. Experimental results of the beam transmission for 20 MeV 19F4+ and 24 MeV 19F5+ ions.
FC-target

FC1

FC2

FC3

FC4

FC5

φ2

φ1

φ0.6

19 4+

2700

1300

1950

350

115

16

5

2.5

19 5+

2500

1150

1950

450

225

-

11

6.3

F (nA)F (nA)

Acknowledgement
This work is supported in part by the Grand-in-Aid for Scientific Research (A) of the Ministry of
Education, Science, Sports and Culture.
References[1] A. D. Dymnikov, T. Ya. Fishkova and S. Ya Yavor, Sov. Phys. Tech. Phys. 10 (1965) 340.
[2] K. Crandall and D. Rusthoi, “TRACE-3D Documentation”, third edition,
Los Alamos National Laboratory Report LA-UR-97-886(1997).
[3] F. Ajzenberg-Selove, Nucl. Phys. A475(1987)163.

-8-

1.3

Development of a proton polarimeter using a liquid
helium target and a measurement of the polarizations of
the 52 Cr(d,p)53Cr reaction

K.Sawada, M.Yamaguchi, T.Katabuchi, Y.Tagishi
We have developed a proton polarimeter using a liquid helium target for double scattering experiments[1]. Fig. 1 shows the vertical section of the polarimeter. The polarimeter target was liquid helium held in a
conical cell. It was connected to a helium tank. The helium tank was supported by the stainless steel pipes
and fixed to an upper flange of the polarimeter. The helium tank was surrounded by a liquid nitrogen tank.
The polarimeter was improved by keeping tightly the thermal insulation. First, to cut heat radiation,
the liquid helium tank was covered with the copper foil. Thickness of the foil was 0.5 mm. The foil wasconnected to the liquid nitrogen tank by using cryogenic high vacuum grease for the purpose of thermal
conduction.
Secondly, the top of the each pipe of the helium tank was connected to the liquid nitrogen tank witha bundle of copper wires. By the bundles of wires, the tops of the pipes were refrigerated and heat flowfrom the upper flange to the the helium tank was reduced. The length of each bundle was about 25 cm.
The combined cross section of the bundle wires was about 0.45 cm2 .
The evaporation rate of the liquid helium was measured and thermal inflow was estimated. It was
about 240 mW. The value was consistent with the value calculated from thermodynamics.
−
By using this proton polarimeter, we measured polarization of the reactions 52 Cr(d,p)53 Cr to 32−
state at g.s. and 12 state at 564 keV at three laboratory angles 15◦ , 20◦ , 30◦. The polarimeter was set atthe focal position of QDQ spectrometer[2]. The 52 Cr target was self supporting foil with a thickness ofapproximately 0.5 mg/cm2 . We used effective analyzing powers of the polarimeter that had been measured
before [1]. Figure 2 show the measured polarizations.

References[1] M. Yamaguchi et al., UTTAC Annual Report, 66, 7(1998).
[2] Y. Aoki et al., UTTAC Annual Report, 52, 19(1987).

-9-Fig. 1. The vertical section of the polarimeter.
0.4
1/2 3/2 0.3

0.2

Polarization

0.1

0

-0.1

-0.2

-0.3

-0.4
10

15

20

25

30

35

Angle(lab)Fig. 2. Polarizations for The 52 Cr(d, p)53Cr reaction to 32- 10 -−−

state at g.s. and 12 state at 564 keV.

1.4

Development of oven type cluster ion source

T.Miyazaki, I.Arai and S.M.Lee
Recently research of nanostructures of using clusters has become one of the leading topics inthe fields of both fundamental physics and applications. Especially, the behavior of size-selectedclusters deposited on the substrate takes more attention. [1] For such research, we need an
intense cluster ion source which can provide a beam of size-selected cluster ions with proper
intensity.
A cluster ion source is decomposed into three parts from its functional view point as follows.
(1) a region for making vapor of material(2) a region for growing clusters by cooling the vapor of material with noble gas(3) a region for ionizing clusters
The intensity of cluster beam mainly depends on the operating conditions in the regions (1) and(3). The evaporation rate from the surface of material and the ionization efficiency are theparameters to determine the maximum available intensity of cluster beam. The distribution ofcluster size mainly depends on the operating conditions in the region (2). The vapor of material
is cooled down by multiple collisions with noble gas atoms while the large-sized clusters growthrough the aggregation of vapor atoms. The pressure and temperature of the noble gas and thelength of the tube, i.e., the aggregation length, are the parameters to control the distribution ofcluster size.
The main difference among the ion sources so far developed is found in their methods ofvaporization, e.g., the laser ablation, the sputtering with high energy particles and the thermal
heating. An oven type cluster ion source uses a method of Joule heating to vaporize material.
Although this methods is applicable only for materials with low melting point and high vapor
pressure such as Na, K and Pb, it’s quite simple and convenient to achieve a considerable
increase of the amount of vapor with the least expense.[2] Under these conditions, we’vedeveloped of a homemade oven type cluster ion source for the research of nanostructures.
Fig.1 and Fig.2 show a schematic drawing and pictures of our cluster ion source, respectively.
The metal vapor coming from the first nozzle joined to the crucible is cooled down by thehelium gas in the aggregation tube contacted with liquid nitrogen . The first nozzle controls theflow of metal vapor and suppresses the dispersion of flow, i.e., a main cause of the beam
intensity loss. In the aggregation tube, the metal vapor atoms condense to form clusters. The- 11 -

mixture of helium atoms and metal clusters is guided via the second nozzle into the ionization
region maintained at a pressure of 10-4torr by using a diffusion pump (Varian VHS-6) with a
pumping speed 3000 l/s for helium. A certain part of the clusters are ionized by an electron
impact method applied in the ionization region and accelerated horizontally toward the beamtransport joined to the TOF mass analyzer. The advantage of the developed system is thatneutral particles flow out vertically and only charged particles are extracted horizontally by theelectrical field. With this configuration, we can completely get rid of the contamination ofuseless particles. To achieve a good connection and sealing between the first nozzle and the
crucible, we designed the crucible as follows. An aluminum crucible ( 8mm×100mm) is
screwed and attached to the first nozzle ( 2mm×6mm). The joined structure is put into analuminum oxide crucible wound with a MnNi ribbon heater (2×6mm2×1300mm,≈6Ω). For−8example the ejection rate of sodium from the first nozzle is evaluated as 6.2 × 10 [mole/sec]
when the crucible’s temperature Ts is 620K,which means a saturated vapor pressure 0.1torr for

sodium. We can keep this flux for several weeks in the case when the half volume of thealuminum crucible is filled with around 5cc of sodium.
The crucible is mounted on a movable supporting rod to adjust the distance L between the first
nozzle and the second one over the range from 0 to 20 cm. L affects the size distribution of metalclusters. We can control the pressure of helium gas in the aggregation tube by adjusting its flow orby changing the conductance of the second nozzle. When we set 50scc/m in as a helium gas flow
and use the second nozzle of the size

3mm×10mm, the pressures of inside and outside of the−4

aggregation tube are 0.75torr and 0.75 × 10 torr, respectively. This condition is similar to the ones
used in other cluster ion sources.[3][4] Under this pressure condition, the heat conduction from the
crucible to the aggregation tube is mainly due to the helium viscous flow, which is independent of
the pressure of helium gas but inversely proportional to the distance X between the crucible and thewall of aggregation tube. The heat loss from the crucible is calculated as 24W when Ts =620K, Ps=1
torr and X=15mm. It is not large compare to the latent heat of vaporization of liquid nitrogen. We
can cool down the helium gas below 100K with any effort.

To ionize neutral particles, we use a heat cathode plasma method.[5] W wire( 0.20mm) is
heated up around 2300 K by Joule heating and eventually ejects thermal electrons. The wire isbiased to –100V against the second nozzle kept at the ground voltage. As a result, the thermal
electrons are accelerated to have energies to ionize neutral particles. It is reported that an
ionization efficiency of 20% has been achieved by combining the accelerated thermal electrons
with permanent magnets.[4] We got 10-4 as an ionization efficiency without permanent magnets.
This value is a typical one for a weakly ionized plasma.
In present, we have achieved a beam intensity of 100nA for sodium. The beam contains all the- 12 -

sizes of clusters. We’ve not known the mass distribution clusters. The next step is to combine a
TOF mass analyzer with our cluster ion source and examine adequate operating conditions forthe production of size-selected cluster ions.

TOF push electrodeDiffusion pump
VHS-6

beam transport line

ionization region
second nozzle

first nozzle

aggregation tube

crucible
movable rod

helium gas line

Fig. 1

Schematic drawing of cluster ion source.

- 13 -

D.P. pumping line

beam line

vapor line(a) Crucible(b) Aggregation tube

fig.2.

Pictures of cluster ion source.

References.
[1] P.Jensen,

Rev. Mod. Phys., 71(1999)1695.

[2]Clusters of Atoms and Molecules I and II, edited byH.Haberland,(Springer,Berlin,1994).
[3] U.Zimmermann, et.al. , Z.Phys. D31, (1994)85.
[4] I.M.Goldby, et.al., Rev.Sci.Instrum. 68(1997)3327.
[5] L. Valyi, “Atom and ion sources” (John Wiley &Sons, London,1977).

- 14 -(c) Whole setup

2.1

Polarization transfer in the 2H(d,p)3 H reaction at θ = 0◦
at very low energies

Tatsuya Katabuchi, Kohei Kudo, Kazuyuki Masuno, Tomoyuki Iizuka, Yasuo Aoki, and Yoshihiro Tagishi
The fusion reactions 2 H(d,p) 3 H and 2 H(d,n)3 He in the sub-Coulomb energy region have beenstudied with great interest because of a suggestion that the reactions initiated by two parallelpolarized deuterons would be suppressed, thus leading to “neutron-lean” fusion reactors [1]. Thissuggestion has aroused controversy because no direct spin-correlation measurement has been performed due to the diﬃculty in developing a polarized deuteron target and theoretical predictions
from several models conﬂict. For more understanding of the mechanisms of this reactions, wehave measured the polarization transfer coeﬃcient Kyy for the 2 H(d,p) 3H reaction at a scattering angle of 0◦ at very low energies (≤ 90 keV). The preliminary results have been previously
reported[2, 3]. In this report, we describe the latest experimental results and comparison with atheoretical prediction.
The experimental detail was described in the previous reports[2, 3]. Thus we here explain theexperimental condition brieﬂy. The experiments were performed with a 90-keV polarized deuteronbeam from a Lamb-shift polarized ion source at UTTAC. We used a proton polarimeter using
p - 28 Si elastic scattering to measure the polarization of protons from the 2 H(d,p) 3 H reaction.
A silicon solid-state detector was used as the analyzing 28 Si-target of the proton polarimeter,
so that the background events could be reduced by requiring coincidence between the analyzing
detector and the scattered-proton detector of the polarimeter. Deuterated-polyethylene (CD2 )nwith a thickness of 10 µm deposited on a 15-µm thick Al foil was used as a deuteron target.
The incident deuteron beam was stopped by the (CD2 )n target. An incident deuteron, losing its
energy in the target, can react with a target deuteron at lower energies than the incident energyof 90 keV. The mean value of the reaction energy estimated from the reaction cross sections[5] and the stopping powers of (CD2 )n for deuterons is 68 keV [6]. The polarization transfercoeﬃcient Kyy was obtained by measuring separately the double-scattering yields of the incident
deuterons in the mI = +1 and mI = −1 magnetic substates from the polarized ion source
for the spin-quantization axis oriented at an angle of 54.7◦ from the beam direction. The spinquantization axis was controlled by the Wien-ﬁlter system of the polarized ion source. As a result,the polarization transfer coeﬃcient Kyy was determined to be 0.09 ± 0.10. The error includes
statistical errors for the proton polarization measurement (±0.08) and uncertainties associatedwith the ion source and the proton polarimeter (±0.04).

We compared our experimental estimate of Kyy with a value calculated using the transition
amplitudes determined by Lemaı̂tre and Schieck in Ref.[4] for the 2 H(d,p) 3H reaction. In theanalysis, using a simple barrier penetrability model, they determined all low-energy transition
amplitudes for the 2 H(d,p) 3 H and 2 H(d,n)3He reactions from a ﬁt to the Legendre expansion coeﬃcients of the experimental data for the cross section, analyzing powers and proton polarizationinduced by unpolarized deuterons for Ed < 500keV. The calculated results for incident energies of
10 and 90 keV and the experimental estimate are shown in Fig. 1. The measured value is a meanof Kyy over deuteron reaction energies lower than an incident energy of 90 keV. The correspondingtheoretical mean, evaluated from an energy-integration over the calculated Kyy weighted with thereaction cross section, is 0.25 (shown in Fig. 1 as a triangle). The experimental result diﬀers fromthe calculation from the transition amplitudes by 1.5 standard deviations. For further discussion
about the suppression of the d + d reactions, the values of Kyy calculated from other models forthe d + d reactions should be compared with the present experimental value.

- 15 -

References[1] R. M. Kulsrud, H. P. Furth and E. J. Valeo, Phys. Rev. Lett. 49, 1248 (1982)[2] T. Katabuchi, K. Kudo, K. Masuno, T. Iizuka, Y. Aoki and Y. Tagishi, in Proceedings of the
14th International Spin Physics Symposium (SPIN2000), Osaka, October 2000
[3] K. Kudo, T. Katabuchi, K. Masuno, T. Iizuka, Y. Aoki and Y. Tagishi, UTTAC Annual
Report 1999, 28 (2000)[4] S. Lemaı̂tre and H. Paetz. gen. Schieck, Ann. Phys. 2, 503 (1993)[5] R.E.Brown and N.Jarmie, Phys. Rev. C41, 1391 (1990)[6] J. Biersack and J. F. Ziegler, TRIM89, version-5.1 (1989)

0.4(d,p) 90keV(d,p) 10keV

0.2

Ky

y'

0
-0.2
-0.4
0

50

100

150

θc.m. (degree)Fig. 1. The measured polarization transfer coeﬃcient Kyy (solid circle), the values calculated fromthe transition amplitudes determined by Lemaı̂tre and Schieck in Ref. 4 (solid and dashedcurves), and the mean value of the calculated value over the incident energies (triangle).

- 16 -

2.2 α) and (p, α) reactions in the
Analyzing powers for the (d,continuum at an incident energy of 20 MeV

K.Masuno, T.Katabuchi, M.Yamaguchi, N.Kawachi, K.Kudo, K.Sawada, T.Iizuka and Y.Tagishi
Continuum energy spectra of emitted particles from nuclear reactions have been studied toobtain information on relaxation process from a simple state well-described by the shell modelto an complicated equilibrium state of nuclei. Kozlowski et al. have derived the ratio of energy
relaxation time to spin relaxation time of nuclei from the analyzing powers of (p, α) reactions incontinuum using a spin relaxation model[1]. In the present work, we have measured analyzing
powers of (p, α) and (d, α) reactions on several targets at an incident energy of 20 MeV andevaluated the ratio of the energy to the spin relaxation times for the reaction 100 Mo(d, α) basedon the Kozlowski model.
For particle identiﬁcation over a wide dynamic range for α particles, we used a ∆E-E countersystem consisting of a proportional gas counter as a ∆E-counter and four silicon solid state
detectors (HAMAMATSU S3204-06) as E-counters. The proportional gas counter had a large
window with an area of 200 × 20 mm2 . The silicon detectors had an area of 18 × 18 mm2 ,were placed behind the gas counter and separated from each other in 10◦ steps. The anodes ofthe silicon detectors were connected in series through resistances. We could clearly distinguishsignals of the counters from each other by the charge division method with a position detector
analyzer (ORTEC464). The energy signals of the detectors were obtained from the cathodes. We
reduced background events by requiring a coincidence between the gas counter and one of thesilicon detectors.
Experiments were performed at UTTAC using polarized protons and polarized deuterons at
an incident energy of 20 MeV. Polarized protons and deuterons from a Lamb-shift polarized ion
source were accelerated with a Pelletron 12UD tandem accelerator. The accelerated polarized
protons or deuterons bombarded a target in a scattering chamber with a diameter of 90 cm. Selfsupporting enriched targets of 58 Ni, 92 Zr, 94 Mo, 100 Mo, 208 Pb and 197 Au were used. Continuum
spectra from a mylar foil and a natural carbon foil bombarded with 20-MeV protons and deuterons
were also obtained to eliminate undesired contribution of carbon and oxygen contamination tocontinuum spectra of (p, α) and (d, α) for the enriched targets. The beam polarization was
obtained by a quench ratio method.
We measured the angular distributions of the analyzing power Ay for the (p, α) reactions
from the 58 Ni, 92 Zr, 94 Mo, 100 Mo, 197 Au and 208 Pb targets and the analyzing power iT11 for the(d, α) reaction from the 100 Mo target. The obtained results for 100 Mo(p, α) and 100 Mo(d, α) at
laboratory angles from 80◦ to 120◦ are shown as functions of outgoing α-particle energy in Figs.
1 and 2. The analyzing power iT11 for the reaction 100 Mo(d, α) is found to increase as α-particle
energy increases in contrast to Ay for the 100 Mo(p, α). This behavior of iT11 for the reaction
100
Mo(d, α) agrees with an expectation from the Kozlowski model that a projectile loses gradually
its energy and polarization in the target nucleus by successive two-body interactions and, as aresult, the vector analyzing power decreases as outgoing particle energy decreases. Thus, weestimated the ratio of energy relaxation time to spin relaxation time from the experimental datafor 100 Mo(d, α) based on the Kozlowski model. We modiﬁed the Kozlowski model for deuteroninduced reactions. In the modiﬁed Kozlowski model, the vector analyzing power iT11 is expressed
as follows:
iT11 (E ∗) = iT11(0)[1 −

E∗ β
]
EM

(1)

where E ∗ is the excitation energy of the residual nuclei, EM is the maximum energy of the emitted
α-particles (EM = Ed + Q in c.m.) and β is the ratio of the energy to the spin relaxation times- 17 -

(β = τe /τs ). The value of EM is 27.7 MeV in 100 Mo(d, α) reaction at an incident energy of
20MeV. From a least-squares ﬁtting to Eq. 1, we obtained the values of β = 5.11 ± 0.55 andiT11 (0) = 0.30 ± 0.04. The ﬁtting result is shown in Fig. 3 as a function of excitation energy of
the residual nucleus, E ∗ .

References[1] M.Kozlowski et al., Nucl. Phys. A449,251 (1986)
0.1

0.3
80 deg.

90 deg.
0.05

90 deg.

0.25

100 deg.

100 deg.

110 deg.

0.2

120 deg.

110 deg.
120 deg.

0

0.15

Ay

iT11
-0.05

0.1

0.05

-0.1

0
-0.15

-0.05
-0.2
8

9

10

11

12

13

14

15

16

-0.1
5

Fig. 1. Experimental data of Ay for the
100
M o(
p, αX) reaction

80 deg.
90 deg.
100 deg.

0.2

110 deg.
120 deg.

0.15

iT11

f(x)
0.1

0.05

0

-0.05

-0.1
0

5

10

15

20

25

Fig. 2. Experimental data of iT11 for the100 αX) reaction
M o(d,

0.3

0.25

10

Outgoing Alpha particle Energy (MeV)

Outgoing Alpha particle Energy (MeV)

15

20

Residual Nucleus Excited Energy (MeV)

Fig. 3. Experimental data of iT11 for the100 αX) reaction as a function
M o(d,of excitation energy of the residual
nucleus and a ﬁtting result to Eq. 1
based on the Kozlowski spin relaxation model (solid line).

- 18 -

2.3

 α)4 He reaction at an inAnalyzing power T20 for the 6Li(d,cident energy of 90 keV

T.Iizuka T.Furui T.Katabuchi and Y.Tagishi
The reaction 6 Li(d, α)4He at energies below the Coulomb barrier has been studied to understand nucleosynthesis in the early universe. The cross sections of the reaction 6 Li(d, α)4He at
the low energies have been measured. From the experimental data of the cross sections, someresearchers have suggested that the reaction 6 Li(d, α)4He may be dominated at low energies by abroad 2+ subthreshold resonance in the compound nucleus 8 Be[1]. In the present work, we haveﬁrst measured the tensor analyzing power T20 of the 6 Li(d, α)4He reaction at an incident energyof 90 keV for more understanding of the reaction mechanism for this reaction.
The emitted alpha particles were detected simultaneously by ﬁve silicon photodiodes (HAMAMATSU S2744) placed in a scattering chamber at every 20◦ from +40◦ to -40◦ in the laboratory
system. Each anode of photodiodes was connected with a resistance in series and each cathodewas also connected in series without resistance. We could clearly distinguish signals from eachcounter by applying a position detecting method with charge division (Fig.1) and also energy
signal of each counter was obtained from cathode. The solid angle of each counter was 20 msr,
which corresponded to a detector angular acceptance of ∆θ=3◦ .
Experiments were performed with 90-keV polarized deuteron beam from a Lamb-shift typepolarized ion source at UTTAC. The target of 6 Li was prepared by vacuum evaporation of 6 Li2 CO3
onto a 15-µm-thick aluminum foil, whose thickness was about 10 µg/cm2 . The energy loss of theincident deuterons in the 6 Li2 CO3 target was estimated about at 5 keV. The deuteron beam wasstopped by the aluminum backing. Measurements were made on the polarized-beam injection line
by setting a small scattering chamber just after a quadrupole magnet followed by a Wien ﬁlter.
The analyzing power T20 was obtained by measuring each cross section of the incident deuteronbeams with the mI=+1 and mI=0 deuteron magnetic substates from the polarized ion source forthe spin-quantization axis parallel to the beam direction. The obtained angular distribution of
the analyzing power T20 is shown in Fig. 2. As shown in Fig. 2, the center of the detectorarrangement was shifted toward approximately 5 degrees from the incident beam line. A more
systematic measurements are now in progress.

References[1] K. Czerski et al., Phys. Rev. C55, 1517 (1997)- 19 -

ID = 0 : PM10^.DAT
50

40

30

20

10

0
0

200

400

600

800

1000

Fig. 1. Position spectrum from the photodiode counter array. Each peak corresponds to the signal
from each photodiode counter.

0
-0.1
-0.2
-0.3
-0.4

T20

-0.5
-0.6
-0.7
-0.8
-40

-20

0

20

40

60

Angle(c.m.) α)4 He at Ed =Fig. 2. Angular distribution of the analyzing power T20 of the reaction 6 Li(d,90keV .

- 20 -

2.4

Measurement of proton total reaction cross sections for nat Sinear the 28 Si(p,n) threshold energy (II)N. Okumura, T. Joh, Y. Honkyu, K. S. Itoh1 and Y. Aoki
An energy dependence of proton total reaction cross sections on nat Si and 27 Al nucleus wasreported in ref. [1]. A resonance like behavior is observed in the case of nat Si around 28 Si(p, n)threshold energy (15.7 MeV). On the contrary, the total reaction cross sections of 27 Al target
increase monotonously with the energy in the range from 14 to 17 MeV. In this energy region,
numerical data on proton elastic scattering cross sections are available [2]. The optical model
calculation, which reproduced these elastic data, fails to predict the resonance behavior.
900

σr [mb]

800
700
600
500

Exp. result
CC

400
14

14.5

15

15.5

16

16.5

17

17.5

Ep (MeV)Fig. 1. Comparison of coupled channels analysis (CC) with the experimental data.

Allowing for a possibility of higher order eﬀects, coupled channels calculation was tried. In
this calculation, potential parameters which can reproduce the elastic and inelastic scatteringcross sections from ref. [2] was searched. The inelastic scattering data was limited to the crosssections leading to the 1st excited state in 28 Si. Coupled channels calculation, which we used
CHUCK2 code [4], solves the following set of coupled equations,d2
( + 1)
2
I
α
{ 2−
+
(k
UαI  α (r)uαα (r).
(1)
 − Uα α (r))}u α (r) =
α
dr
r2


α =α

Suﬃces α and α denote sets of channel quantum numbers. The superscript α shows the entrance
channel. The 28 Si(gnd.), 28 Si(2+1 ) and (p,n) states are included in this calculation. Total reaction
cross section σr can be expressed as ∞σr (r)dr
(2)
σr =
0

∞

2π 
απI∗
=
(2j
+
1)
Im{u
Uαα uαπI(3)αα }dr.
k3
0

j

α

Following form of coupling potentials are assumed, i.e.,
for the coupling with ground and 28 Si(2+1 ) state,


2
2mα 
d(n)f (XR )d(n)f (XI )U (gnd. → 1st) = 2
Vn
,
+ iWn
(n)
(n)
h̄ n=1dX
dX
1R

Cyclotron and Radioisotope Center, Tohoku University, Sendai 980-8578, Japan- 21 -

I(4)

where f (XR ) and f (XI ) are Wood-Saxon type function and mα is the channel reduced mass,and for the (p,n) reaction,
U (p → n) =2mα exp(−µr)
V
r
h̄2

2mα
V δ(|r − r0 |),
h̄2

or

(5)

σr(r) [fm2/fm]

respectively. The result of this analysis is compared with the experimental data (ﬁg. 1). A
resonance like behavior in the calculation can be seen around the (p,n) threshold energy, Theerror bar of the coupled channels calculation shows the range where the χ2 is increased by 1/3
from the minimum χ2 . To compute this range, the strength of the imaginary part of the potential
is changed.
The integrand σr (r) in eq. (2) is named absorption distribution in [3]. Upper panel of ﬁg. 2
shows σr (r). Peaks around 4 fm means that the absorption takes place near the surface region of
15.5MeV
15.7MeV
15.9MeV
16.1MeV
16.3MeV

2.0
1
0
0

2

4

6

8

12

15.5MeV
15.7MeV
15.9MeV
16.1MeV
16.3MeV0.2

σr(r)−<σr(r)>E

10

0.1
0
-0.1
-0.2
0

2

4

6
radius [fm]

8

10

12

Fig. 2. The upper panel of the ﬁgure shows the absorption distribution around the thresholdenergy. The lower panel shows the absorption distributions, where energy averaged absorption distribution is subtracted.

the target nucleus. The peak value is a little smaller for 15.5 and 15.7 MeV than the rest. The
lower panel shows the energy dependence of the deviation of σr (r) from the energy averaged one( σr(r) E ). This ﬁgure shows that the 15.7 MeV curve has a large negative value near the nuclear
surface. At 15.9 MeV the dip near the nuclear surface is drawn into the center by about 1 fm andthe dip change sign and pushed out to nuclear surface when the incident energy is increased to16.1 and 16.3 MeV. This energy dependence of absorption distribution can clearly be seen using
absorption radius as the ﬁrst moment of the absorption distribution [3],rabs =rσr(r)
.
σr(r)

(6)

Fig. 3 shows the energy dependence of the absorption radius due to the coupled channels
analysis. The absorption radius becomes about 0.1 fm smaller around 15.6 MeV. If the geometricalcross section is estimated with the absorption radius, this decrease in the absorption radiuscorresponds to 30 mb reduction. The experimental data of total reaction cross section in theref. [1] has a dip whose depth is about 50 mb. So the absorption radius shows the same tendency
as the experimental total reaction cross section.

- 22 -

4.3

rabs [fm]

4.2

4.1

4.0
15

15.5

16

16.5

17

Ep [MeV]Fig. 3. Energy dependence of the absorption radius rabs .

References[1] N. Okumura, N Takahashi, T. Joh, Y. Honkyu, M. Kitazawa, K. S. Itoh and Y. Aoki,
UTTAC annual report (1999) 35[2] K. Hirota, 28 Si(p,p) data, private communications[3] Y. Aoki, K. Hirota, H. Kishita, K. Koyama, M. Masaki, K. Miura, Y. Mukouhara, S. Nakagawa, N. Okumura and Y. Tagishi, Nucl.Phys. A599,417(1996)[4] P. D. Kunz, computer code CHUCK2, private communications- 23 -

2.5

Toward proton-proton scattering at forward angles (III)T. Joh, K. S. Itoh, N. Okumura, Y. Honkyu, M. Aramaki and Y. Aoki
The study of p-p differential cross section at energies around 20MeV has been continued [1]. It wasreported in ref [1] that the proton elastic spectrum is degraded by a beam halo and slit edge scattering. An
effort was made to improve the quality of the spectrum by installing a slit with four jaws, which can be
moved independently. By reading the beam current intensities, which hit these four jaws, are used toestablish a good beam transportation. A typical momentum spectrum obtained with the new set up isdisplayed in Fig. 1.
This spectrum was taken at a laboratory angle of +4 degree with a proton beam energy of 22MeV. The
prominent peak in this spectrum is due to the p-p scattering. The continuous tail observed at thelow-momentum side decreased to 0.2% level. Protons elastically scattered from contaminant carbon and/or oxygen are negligible. There remains left/right asymmetry in elastic yield at 4 degree. It was noticed
that there was a little misalignment of target chamber and a magnetic spectrograph. This misalignment
was corrected to less than 0.1 mm.
We are now directing our effort to the operation of monitor counter. It is a plastic scintillator coupledwith a 1/2” photo multiplier tube. It is located at 25 degree right from the target center.

4

10Counts/Channel

1000

100

10

1
0

200

400

600

800

1000

Channel Number

Fig. 1: momentum spectrum of 1H(p,p) at 22 MeV

Reference[1] T. Joh, K.S. Itoh, N. Okumura, N.Takahasi, Y. Honkyu, M. Kitazawa and Y. Aoki, UTTAC annual
report (1999) 38- 24 -

2.6

Measurement of the proton spectrum in deuteron break-up
reaction

Y. Honkyu, N. Okumura, K. S. Itoh1) , T. Joh, M. Aramaki, and Y. Aoki
We have developed a counter system to measure proton spectra in deuteron break-up reactions[1,2]. It is a 1300 mm long position sensitive detector and is designed as a focal-plane detecter for
an Enge-type Split Pole magnetic spectrograph (ESP90)[3].
Fig.1 shows the current version of the counter assembly. It consists of two position-sensitive
detectors and an energy detector. The position-sensitive detectors are single wire proportionalcounters (SWPC). The anode wire is 12.5 µm in diameter, and is 1200 mm long. The anode-tocathode gap is 5 mm wide. The cathode is made of 4 µm thick aluminized myler. The countergas is a mixture of 70% Ar and 30% methane. Position information can be extracted by chargedivision method. The energy counter is composed of a plastic scintillator and two photomultipliertubes. The plastic scintillator is about 900 mm long, and its thickness of 15 mm is enough tostop protons and deuterons. Two photomultiplier tubes are set on both sides of the scintillator.
E-counter

SWPC

900mm
1290mmFig. 1. Counter assemblyOﬀ-line tests were carried out for the SWPC using 5.9keV X-rays from 55 Fe source. The
position resolution of the SWPC was improved from 2.4 mm to 1.5 mm(FWHM).
A proton spectrum in deuteron break-up reaction was measured by using 18 MeV deuterons
and 208 Pb target(3.89 mg/cm2 ). The data were taken in ﬁve-degree steps from θlab =20◦ to 55◦ .
Triple coincidence in two SWPC and the energy detector was observed to determine proton
events. A typical two dimensional coincidence spectrum is displayed in Fig.2. Fig.3 shows the
proton momentum spectrum obtaind by projecting the two-dimensional spectrum onto the position axis. Protons in the ﬁgure come partly from the break-up reaction (d,pn) and partly from(d,p) reactions. Fig.4 shows the double diﬀerential cross section.

References[1] Y.Sinbara and S.Kuroki, Thesis, Tsukuba University, (1997)[2] N. Takahasi, K. S. Itou, N. Okumura, T. Joh, Y. Honkyu, M. Kitazawa, K. Hirota1 andY. Aoki , UTTAC annual report (1999) 22[3] J.E.Spencer and H.A.Enge, Nucl. Instr. and Meth. 49, (1967), 181

1

Laboratory of Nuclear Science, Tohoku University- 25 -

1000

800

600

400
400

600

800

1000

1200

1400

1600

position(ch)Fig. 2. Two dimensional spectrum

countsInelastic scattering for d+208 Pb and θlab =30◦ at Ed =18 MeV

180
160
140
120
100
80
60
40
20
0

30deg.

400

600

800

1000 1200 1400

positionFig. 3. Momentum spectrum

200∂σ(mb/sr·MeV)∂θ∂E

30deg.

150
100

2

dE/dx(ch)

1200

50
0
8

9

10

11 12 13 14
energy(MeV)

15

16

Fig. 4. Double diﬀerential cross section

Inelastic scattering for d+208 Pb and θlab =30◦ at Ed =18 MeV.

- 26 -

2.7

Yrare Bands in 119Xe

C.-B. Moon1, T. Komatsubara , Y. Sasaki, T. Jumatsu, K. Yamada, K. Satou, and K. Furuno

The transitional nuclei, such as Xe and Ba in the A=120-130 mass region have attracted much attention
since they provide the useful information helped to understand, in the framework of the cranking model,
the polarizing effect of the valence quasiparticles on the nuclear shape. In this mass region the proton
Fermi surface lies in the lower part of the h11/2 subshell while the neutron Fermi surface lies in the h11/2
midshell. Thereby, the nuclei in this mass region are soft with respect to γ, the triaxiality parameter in thepolar description of quadrupole shapes. Total Routhian surface (TRS) [1,2] and cranked shell model(CSM) [3, 4] calculations suggest that these high-j valence particles exert a strong and specific driving
force on the γ–soft core: particles in the lower part of the h11/2 subshell favor a collectively rotating prolate
shape (γ ≥ 00 in the Lund convention) while those in the middle part of the h11/2 subshell favor acollectively rotating triaxial shape (γ ≈ -300).
In the even-mass Xe nuclei in this mass region, low-lying γ-vibrational bands have been observed thatshow a pronounced energy staggering between odd and even spin states. This has been interpreted interms of a gamma-soft nuclear potential in their low-lying states. In the odd-mass Xe isotopes, theunique-negative parity h11/2 neutron orbital forms the yrast rotational band and their signature splitting
features can be nicely described by cranking calculations. In the mean time, the second negative-parity
rotational bands based on the high-j h11/2 neutron orbital, they are called the yrare bands, were observed in121

Xe [5], 123Xe [6], and 125Xe [7]. In contrast to the behaviour of the yrast bands where the favored statesshould be lying lower in energy, the yrare favoured states are seen to be energetically unfavoured, namely
the signature splitting is inversed. Such signature inversion in the yrare bands seems to be quite general in
the light odd-mass Xe isotopes. With features in mind, although several studies on high-spin states in
119

Xe [8,9,10,11] were done, we tried to investigate excited states for observing the yrare bands in 119Xe.

In the present work, we report the yrare bands in 119Xe and discuss signature inversion seen in the light
odd-mass Xe isotopes.
The level structure was studied with the 107Ag(16O, p3n)119Xe reaction at a beam energy of 85 MeV.
The beam was provided by the 12UD tandem accelerator at the University of Tsukuba. The target was aself-supporting foil of 107Ag, 6.6 mg/cm2 in thickness. The γ-ray spectra were taken with 11 high-purity(HP) Ge detectors with BGO anti-Compton shields (ACS). One of them was the LEPS (low energy
photon spectrometer) detector to ensure sensitivity for important low-energy transitions at the bottom
parts of γ-ray cascades.
Figure 1 shows the partial level scheme of 119Xe where only the negative-parity states are represented.
The ordering of the γ-ray transitions has been determined from coincidence relationships and relative1

Department of Physics, Hoseo University, Chung-Nam 336-795, Korea- 27 -

intensities.
Band 1, favored yrast states, built on the 11/2- state and its signature partner band 2, unfavoured yrast
states, were already known in the previous works [8-11]. In the present work, we confirmed up to the
43/2- state. In a recent work by Scraggs et al. [11], this favoured yrast band was established up to 83/2-.

Band 143/2-6590.9

119
54

Xe65

987.0
39/2-

5603.9Band 2

969.7
35/2-

4634.24499.0Band 4969.7(29/2-)

31/2-

3664.5

Band 3818.0
3681.0

29/2-

846.7

+
0 5/2

7/2-

0.
8
5
15/2-

575.4

723.6
1229.6

6

21/2-

17/2-

584.8

1934.1

13/2644.8
7
.
1
405.9
398.8 40243.1
11/2246.0
9/2
67.1 70.0
176.0
649.0

(23/2-)

684.6(19/2-)

568.5
1365.6

716
.6

8

19/2-

1224.4

5
5.
6
6

832.3
1953.28.

708.7

2618.770

23/2-

1933.1(27/2-)

769.8

25/2-

709 4.5
.7

7
3
2.
9.
91
75

(13/2-)

820.7

2785.5

85
2.
4

.1

(17/2-)

559.3
1002.4

.7
16
10

679.4
1561.794(21/2-)

27/2-

2753.810785.4
2241.3

895.5

910.7

(25/2-)

72

3026.2

3388.5(15/2-)

720.
83872.933/2-

119

Fig. 1. Partial level scheme of Xe showing the negative-parity states populated from
107
16
119
the Ag ( O,p3n) Xe reaction at Elab = 85 MeV. Excited and transitional energies
are given in keV.

Bands 3 and 4, to which we assign negative parity, were newly identified in the present work. The
population intensity for bands 3 and 4 is estimated to be 11 % and 18 %, respectively relative to that of- 28 -

the 15/2- - 11/2- 406 keV transition in band 1. Thereby, the favoured yrare states, band 3, are lesspopulated than the unfavoured yrare states, band 4. Band 4 is connected to the yrast favoured states
through several interband transitions, namley the 759-913-1017-1094 ones while band 4 is connected toboth the yrast favoured and unfavoured states. Meanwhile, the interband transitions from band 3 arerather strongly populated to the unfavoured yrast band than to the favoured yrast band. The proposed spin
and parity assignments are essentially based on the multipolarity of the interband transitions connecting to
the yrast bands 1 and 2. The DCO ratios indicate that the 913, 1017, and 1094 keV transitions connecting
band 4 to the favoured yrast band are ∆I = 1 transitions with mixed M1/E2. The 721, 705, and 666 keVtransitions connecting band 3 to band 2 are also of dipole character indicating ∆I = 1 transitions with
mixed M1/E2. So we propose that bands 3 and 4 should have negative-parity states. Bands 3 and 4 arecalled the favored and unfavored yrare states. It is seen that the low spin signatures for the unfavoredyrare bands are inverted as compared with those in the yrast bands. Surprisingly, the critical inversionspin, Ic = 12h at which the normal signature splitting is restored, was observed, which is the firstobservation in the odd-A Xe.
References[1] R. Wyss, J. Nyberg, A. Johnson, R. Bengtsson, W. Nazarewicz, Phys. Lett. B 215 (1988) 211.
[2] W. Nazarewicz, R. Wyss, A. Johnson, Nucl. Phys. A 503 (1989) 285.
[3] R. Bengtsson, S. Frauendorf, Nucl. Phys. A 327 (1979) 139.
[4] R. Bengtsson, S. Frauendorf, F.-R. May, At. Data Nucl. Data Tables 35 (1986) 15.
[5] C.-B. Moon, T. Komatsubara, T. Shizuma, K. Uchiyama, T. Sasaki and K. Furuno, Eur. Phys. J A 4(1999) 107.
[6] A. Schmidt, I. Schneider, H. Meise, I. Wiedenhöver, O. Stuch, K. Jessen, D. Weisshaar, C.
Schumacher, P. von Brentano, G. Sletten, B. Herskind, M. Bergstrom, J. Wrzesinski, Eur. Phys. J A2
(1998) 21.
[7] Granderath, D. Lieberz, A. Gelberg, S. Freund, W. Lieberz, R. Wirowski, P. von Brentano and R. Wyss,
Nucl. Phys. A 524 (1991) 153.
[8] P. Chowdhury, U. Garg, T.P. Sjoreen and D.B. Fossan, Phys. Rev. C 23 (1981) 733.
[9] V. Barci, J. Gizon, A. Gizon, J. Crawford, J. Genevey, A. Plochocki and M.A. Cunningham, Nucl.
Phys. A 383 (1982) 309.
[10] V.P. Janzen, M.P. Carpenter, L.L. Riedinger, W. Schmitz, D.G. Popescu, J.A. Cameron, J.K.
Johansson, D.D. Rajnauth, J.C. Waddington, G. Kajrys, S. Monaro and S. Pilotte, Phys. Rev. C 39
(1989) 2050.
[11] H.C. Scraggs, E.S. Paul, A.J. Boston, J.F.C. Cocks, D.M. Cullen, K. Helariutta, P.M. Jones, R. Julin,
S. Juutinen, H. Kankaanpää, M. Muikku, P.J. Nolan, C.M. Parry, A. Savelius, R. Wadsworth, A.V.
Afanasjev and I. Ragnarsson, Nucl. Phys. A 640 (1998) 337.
[12] K. Loewenich, K.O. Zell, A. Dewald, W. Gast, A. Gelberg, W. Lieberz, P. von Brentano, Nucl. Phys.
A 460 (1986) 361.

- 29 -

2.8

Band structures in the doubly odd nucleus 130Cs

Y.-J. Ma, Y.-H. Zhang, Y. Sasaki, K. Yamada, H. Ohshima, S. Yokose, M. Ishizuka, T. Komatsubara and K.
Furuno1. Introduction
There have been extensive investigations on high-spin structures of odd-odd nuclei in the A ~ 130 mass
region. Rich experimental data on band structures and transition probabilities obtained with recent
Ge-detector arrays have revealed a number of interesting features of the nuclear structure in this mass
region like the signature inversion at low spins.
Neutron deficient odd-odd Cs isotopes are well investigated up to high spins by several authors[1-3].
Since even-even nuclei in this region change in their shape from a deformed shape at the neutron-deficientside to spherical shape near the N = 82 closed shell, high-spin band structures in odd-odd nuclie would
also exhibit a systematic behavior with the increase of the neutron number according to the softness for
gamma deformation of the core and the variety of the couplings in the extra-core neutron and proton.
The nucleus 130Cs has 75 neutron; it located between the well deformed and the spherical region. Since
the last extra-core neutron occupies the h11/2 orbital having high-Ω as the increase of the neutron number, it
is expected that a dipole band might be observed in addition to the usually observed competition of thecollective excitations with the single-particle excitations. However, the high-spin sates in 130Cs are lessstudied in comparison with lighter Cs isotopes. This is partly because of the difficulty in the production
via a dominant exit channel of fusion-evaporation reactions with A > 11 projectiles.
Previously, Sala et al. reported three rotational bands of 130Cs [4]. The yrast band was observed up to
14+ state; the configuration was assigned to πh11/2⊗νh11/2, but no backbending was observed. The
configurations of other two bands were assigned to πg7/2⊗νh11/2 and πd5/2⊗νh11/2. During the progress of
this study, some new results of 130Cs became available from a recent publication by Starosta et al [5].
2. Experimental details and data analysis
In the present work high-spin states in 130Cs have been studied through two separate experiments
successively performed at Tandem Accelerator Center, University of Tsukuba (UTTAC). In the firstexperiment 130Cs was produced via the 124Sn(10B, 4n) reaction at a bombarding energy of 47 MeV, and in
the second one via the 124Sn(11B, 5n) reaction at 58 MeV. The same target and same detection system wereused in the two different experiments. The target was a self-supporting 4.6 mg/cm2 metallic foil, enrichedin 124Sn to 99%. The detection system was an array consisting of nine Compton-suppressed HPGe
detectors and one planar HPGe detectors. Energy and efficiency calibrations of these detectors were madeusing 152Eu and 133Ba sources. γ-γ coincidences were measured and the events were collected when at least
two detectors fired in coincidence within 100 ns. In addition, single spectra were also measured in eachexperiment. Approximately 140 and 100 million coincidence events were collected in the first and second
experiments, respectively.

- 30 -

216.9
147.6
170.8

(4+ )

90.5

591.0

173.5
80.3

4+

1113.2

20+

18+

7

7.

17+

10+

9+

9

6.

16

29

16+

15+

5−

96.6

11+

14+

14−

9−

10−

12+

12−
13−

14−

15−

16−

17−

18−

20−

18−

8−
286.7

10−
7.4

16−

223
.4

12− 155.2

38
502.

9

35
6.8

9.5

260
.1
190
.0

11−

96.7

174.8

247
.7

13−

5

7−

8−

33

10−

12−

14−

5.6

6

21−

19−

17−

15−

13−

11−

9−

16−

18−

7

3.0
.8
53

31
3

249.2

9−

148.3

1+

8−

10−

15−
14−
239.1 −
13
166.5 −
12

16−

17−

see the continuing part

10−

8

Figure 1. Level scheme of 130Cs deduced from the present work. (to be continued)

131.3

151.8

3+ 3+

6+

190.1

183.2 300.9 234.3

117.6

8+ 11
7+

+

9+

13+

15+

17+

19+

8
479.

4

809.9

972.3
988.3

22+

3

470.8

2

31

(Black lines denote previously known states or trnanstions, while red ones denote newly identified states or transitions.)

51.1

189.9

5+

6+
.3

138.9

(4+ )

7+

8+

256

209.8 60.6

(13+ )(13+ )(13+ )

1

.3

83.2

216.6

480.4

1085.4

518.8

662.5

Band

7

435.9

17

40

260

820.1

532.6

559.8

669.6
555.1

731.5

.0

.3

722.3

1043.2

711.2

368.7

1.0

489.7
373.8

638.2

646.1
522.4 197.9

773.7 350

401

936.0

966.6
776.6
961.3
936.8

2 635.1 4 797.0
9
48.2
4.0
789.2
607.0
34

418.1

398.4 457.9
281.0 398.4

6.7 .6

530.3

838.4

1071.71105.671
78 8.9
8.9

2.8

57
3
63 .6
4.2

942.4
821.3

.5

1021.1505.4 2465 958.4
450 992.1
90 707.6 426 896.2
.8
.8
.9
.4
844.3
644.0 677
934.9
943.2
.3
547
.5
61
0
.
699.4 595.4 967.6
0
804.0
954.2

5
53.

4

30

2

943.8
809.0

780.5

7

622.1 26

574.

3

32
.

914.2

379
2

.3
417

8.2

.8

647.7

1008.2

.8
42
.7

743.0

61
4
.1 .8

4

883

474

454
.0

911.5
845.8
767.0

.6

866.2
666.9
706.7

- 31 348

4.9

1
69.

.3

372

540

71

4

92.5

714.9

.1

547.5

454

621.6

948.8

562.
3

8
488
.0

663.8

554.
1

2.

411.4
446.3
804.1

7.4
52
824

41.3

90
8
.
0
811
.3

478.7

21

572
.3
.8

.7

967

5

391

.9

591
723.4

.9

366.8 340.3
707.0

436
927.9

1880.7

10 −1821.310 −1629.1

488.0

547.5

11 −

1333.3

591.9

340.3

9−

1288.7

9−

9−

411.3

366.7

707.2

997.6

921.9

446.3

8−
7−

886.9

9−

145.2

878.3

234.5

636.5

303.5

321.1

312.8

618.3
565.5

152.4
226.1

804.1
276.7

102.9

426.2

50.6

96.7
155.8

278.8

270.5

56.2

5 (−)

212.4

115.6

T 1/2 = 3.46 m

263.1

214.3

336.9

4 (−)
5−

375.6

373.7

6−

529.2

500.1

502.9

286.7

511.3

546.4

622.1

242.7

6+

190.0

460.5

6+

350.4

386.9

7−

7−

652.4

392.7

8−

379.3

8−

723.1

7−

776.7

269.5

7 (−)

163.2

Figure 1 (continued). Level scheme of 130Cs. (This part mainly displays the decays of band 6 to lower states)
In the off-line analysis, the spectra were corrected for the Doppler shift depending on the detector angle.
They were then sorted into two separate two-dimensional Eγ-Eγ matrices corresponding to the twodifferent experiments. A summed matrix of the above two matrices was also constructed to enhance 130Cs
as it appeared to be the most intensely populated residue both in the 10B and 11B induced reactions. All
these matrices were symmetrized and were employed to deduce γ-γ coincidence relationships. Likewise,
three asymmetric matrices were constructed for a purpose to extract the DCO ratios of γ transitions.
3. Results and discussions
The level scheme of 130Cs deduced from the present work is shown in figure 1. With all the previously
known [4] rotational bands extended to higher spins, several new bands have also been identified on thebasis of prompt coincidence data. For the convenience of discussion, bands of interest in figure 1 arelabeled with numbers.

- 32 -

3.1.

Band 2, 4 and 5

Bands 2, 4 and 5 are the three rotational bands identified previously by Sala et al [4]. In their work,
these three bands were observed up to spins I = 14, 14 and 12 respectively. Meanwhile, based on
considerations of the parities of the respective bands and on nice agreements between the experimental
and IBFFM (interacting boson-fermion-fermion model) level spectra, these bands were assigned to be
based on the πh11/2⊗νh11/2 πg7/2⊗νh11/2 and πd5/2⊗νh11/2 configurations, respectively. In the present work,bands 2 and 4 have been extended up to spins where the rotational alignment of a pair of quasiparticles
occurs. The configuration assignments proposed by Sala et al are consistent with the observed alignment
properties of these bands.
3.2.

Band 3In the previous work of Sala et al [4], a 610 keV transition was shown to feed the 13+ state of the yrast
band (band 2 in figure 1), in addition to the other feedings. In the present work this 610 keV transition has
been identified as an out-of-band transition from another band, which is band 3 shown in figure 1.
Moreover, we have also observed several other linking transitions, as can be seen from figure 1. Based on
the measured DCO ratios of these linking transitions, band 3 is realized to have positive parity. Band 3
was also observed in the recent work by Starosta et al [5] and interpreted to be built on the same
πh11/2⊗νh11/2 configuration as the yrast band. Furthermore, they demonstrated that such sideband partnerof the yrast band exists systematically in the N =75 isotones 130Cs, 132La, 134Pr and 136Pm, suggesting acommon basis, for which they interpreted in terms of chiral vibration. In comparison with the datareported by them, in our data one additional transition (the 954 keV transition) has been placed on the topof band 3. In addition, two transitions with energy of 298 and 167 keV are observed to decay from theyrast band into the side partner band; see figure 1. Such an observation is interesting since no similartransition has ever been observed in the other three N=75 isotones.
3.3.

Band 6 and 7

Bands 6 and 7 are two new bands disclosed from this work. They are connected quite strongly and band
6 de-excites towards the previously known lower states in a quite complicated decay pattern. The state fedby the 446 keV transition seems to be the bandhead of band 6. As its excitation energy is quite low,comparable to those of the other two-quasiparticle bands, it is thought to be also of two-quasiparticle
instead of four-quasiparticle in nature at low spins. In addition, based on the experimental DCO data, band6 as well as band 7 has been identified unambiguously to be of negative-parity. Taking into account theseobservations and the alignment property of band 6, we have tentatively assigned the πh112/⊗νg7/2
configuration to band 6.
Band 7 is connected with band 6 quite strongly and this feature seems to suggest that it is the anothersignature of the πh112/⊗νg7/2 band. However, an alternative assignment can not be completely excluded, i.e.
the assignment of πh112/⊗νd5/2 configuration.

- 33 -

3.4.

Band 1 and 8

Band 8 appears to be a band-like structure consisting of only low-energy transition compared to theother normal rotational bands. Based on the experimental DCO data and the observation of a large numberof linking transitions from band 8 to other known bands, we have been able to make firm spin and parity
assignments for it, which indicate that it can be classified as a dipole band. Similar bands have also been
observed in a number of nuclei in this region (see e.g. refs. [6,7]). The lowest observed state of band 8 has
a high excitation energy (Ex = 2849 keV), which happens to be quite close to the excitation energy aroundwhich the EF alignment occurs in band 6 and 7, as well as in 129Cs [7]. In view of this feature, we proposethat band 8 is a four-quasiparticle band and the E and F quasineutrons are present in its configuration.
Besides band 8, band 1 also appears to be a dipole band, however they have quite different excitationenergies. The band-head excitation energy of band 1 is only 962 keV, which is so low that it would beunreasonable to assign band 1 as a four-quasiparticle band. Dipole bands of two-quasiparticle in nature
have also been suggested in several other odd-odd nuclei such as in 134La, 136Pr and 138Pm (See ref. [8] andrefs therein). It is worth emphasizing that we have in one nucleus found two types of dipole band, which
are of two- and four-quasiparticle in nature respectively.
4. Summary
In brief summary, high spin states in 130Cs have been studied through the reactions 124Sn(11B, 5n) at abeam energy of 58 MeV and 124Sn(10B, 4n) at 47 MeV. Previously know rotational bands have been
extended to higher spins, and several new bands have also been established. The possible configurations of
the newly identified bands are discussed briefly. Further work of this study is in progress.
References[1] C.-B. Moon, T. Komatsubara, K. Furuno, Nucl. Phys. A674, 343 (2000)[2] T. Komatsubara et al., Nucl. Phys. A557, 419c (1993)[3] E. S. Paul et al., Phys. Rev. C 40, 619 (1989)[4] P. R. Sala et al., Nucl. Phys. A531, 383 (1991)[5] K. Starosta et al., Phys. Rev. Lett. 86, 971 (2001)[6] T. Hayakawa et al., Z. Phys. A 357, 349 (1997)[7] L. Hildingsson et al., Z. Phys. A 340, 29 (1991)[10] U. Datta Pramanik et al., Nucl. Phys. A637, 327 (1998)- 34 -

2.9 Level Structure of 118I
C.-B. Moon1, T. Komatsubara, T. Shizuma, Y. Sasaki, H. Ishiyama, T. Jumatsu, K. Yamada,and K. Furuno
The transitional nuclei with the A = 120 mass region have been extensively studied in the last years
and the resulting experimental information helped to understand the polarizing effect of the valence
quasiparticles on the nuclear shape. In this mass region the proton Fermi surface lies in the lower part of
the h11/2 subshell while the neutron Fermi surface lies in the h11/2 midshell. These high-j valence particles
exert a strong and specific driving force on the γ-soft core: quasiprotons in the lower part of the h11/2

orbital favor a collectively rotating prolate shape at γ ¥ 00 while quasineutrons in the middle part of theh11/2 orbital favor a collectively rotating triaxial shape at γ º -300. In view of such driving effect, thedoubly odd I nuclei have attracted attention since they provide an opportunity to understand the possible
interaction and competing shape driving effects between proton and neutron quasiparticles in the high-j
intruder h11/2 orbitals.
The collectivity in the light I nuclei has been derived from the well-developed quadrupole deformation
built on the neighboring even-even Xe core. In the light odd-A I, the yrast rotational bands were built on
the 11/2- state that is associated with the proton h11/2 orbital. In the meantime, the yrast rotational bands
based on the πh11/2≈νh11/2 configuration were observed in the light odd-odd I such as 116I [1] and 118I [2].

Interestingly, such πh11/2≈νh11/2 rotational bands in the odd-odd Cs nuclei reveal the signature inversion
phenomena, which the excitation energy in unfavored signature states is lower than that in favoredsignature states [3].
Although several investigations for the level structure of 118I by using in-beam spectroscopy were done
[2, 4, 5], reliable spin-parity assignments for the observed rotational bands could not be established since
the bands observed in this nucleus were not connected and thus remain isolated from each other. In thepresent work, we report the new results for the level scheme of 118I.
The level structure has been studied with the 103Rh (18O, 3n) 118I reaction at a beam energy of 85 MeV.
The beam was provided by the 12UD tandem accelerator at the University of Tsukuba. The target of
Rh was a self-supporting foil of 6.8 mg/cm2 in thickness. The γ-ray spectra were taken with sevenhigh-purity (HP) Ge detectors with BGO anti-Compton shields. The level scheme of 118I deduced from103

the present work is shown in Fig. 1. The ordering of the γ-ray transitions has been determined fromcoincidence relationships and relative intensities. Information on γ-ray multipolarities was obtained from
DCO ratios, R = Iγ(370)/Iγ(790).
Bands 1 and 2 have been known in previous works [2, 4, 5] and interpreted as the strongly coupledrotational bands built on the πg9/2≈νh11/2 configuration. The band-head 7- state with the half-life of 8.5m, however, has not been known its excitation energy. In the present work, we propose that theexcitation energy of the 7- state should be 188.8 keV. This result comes from the definite determination
for the1

Department of Physics, Hoseo University, Chung-Nam 336-795, Korea- 35 -

excitation energy of the 10- state in band 6 and the observation of a linking transition of 406.6 keV fromthe 10- state at 942.6 keV to the 9+ state at 536.0 keV, which finally decays to the 7- state through apathway of the 224.6 keV transition.

1033.2
687.0

545.0





7718.6

118
53 65

I





6730.0

31093.6

0
3.





45
9.
8

41
5.
3



0

540.8



1012.2

748.7

652.1

536.0
360.2

(12.9)

T 1/2= 13.7 m

118

942.6 

.2

703.7


373.1 (61.8)
188.8


 

709.2





 





190.4
752.2

25.6

 

123.3

57.0

92.2

0 221.5







317.1




164.8

268.7

392.0

 82.0




 

19 546.5
6.2

5
1.
487.7
29




674.9

628.3 50.4
3



6 .6

40
4.
1

822.1




 

8.0
24

T1/2 = 8.5 m

7.
39

636.8

476








775.3

744.1
 





912.8


 

.4

798.2

28 529.3
1.3
 

461.5

1076.8
896.6

  224.6

122.5



8

 

4
8.

4. 3

4





5
52 3.

523.0

9.

311.3



8. 3

22







29

29

576.4


 


48

.9

626.5 3.6



.9
190

696.1

.9
995

.1

33
2

 


 

2

30



804.4

9
38
3.

700.3

911.7



9 90

3
9.






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864.1

760.3





6.3
24

43
36





3049.0

 



 

752.3










 





3050.5



811.7

1007.8

822.1

401.5

899.1





875.3



854.6





7





 



 

 



811.0

48







982.5

942.8


798.0

983.0



6

 

962.2

40



 

32
8.
2

 



914.2









 

5234.8 

1008.6



5

4



 

1

1068.7



.5
426

401.6

2

B

988.6

A

129.0
103

18

118

Fig. 1. Level scheme of I deduced from the reaction of Rh( O, 3n) I at E lab = 85 MeV.
Transition and excitation energies are given in keV. The widths of the arrows correspondroughly to the intensities of the γ -ray transitions.

Bands 3 and 4, to which we assign positive parity, was already identified by Paul et al. [2] as adeformed rotational band built on the πh11/2≈νh11/2 configuration. Such a configuration was obtained by- 36 -

the blocking arguments for the quasiparticle spin alignment. In the present work, we confirmed theirresult and determined the excitation energies.
Band 5 was newly identified in the present work. This band shows a regular sequence of E2 transition
up to the 15 state where its structure changes showing a quasiparticles alignment.
Band 6, which is the yrast band, and its signature partner, band 7 were already reported in [2, 5]. The
excitation energy and spin assignmet to the state of band head, however, could not be established.
Noncollective low spin states below the 8- state at 752.2 keV, labeled A, consist of the complicatedtransitions. The ground state of 118I has been know to have the spin and parity of 2- with a magnetic
dipole moment 2.0 nm and a half-life, T1/2 = 13.7 m [6]. We suggest that low spin transitions labeled A
should be built on the ground state. Bands 6 and 7 could be interpreted as the πg7/2≈νh11/2 quasiparticle
structure.
Band 8 was reported in [4] but the ordering of the transitions are quite different from each other.

Considering the coincidence relationships and intensities of the γ-ray transitions, our result is morereliable. This band can be built on the four quasiparticle excitation and the 24- state may be interpreted interms of a noncollective oblate state with the full configuration of [νg7/2≈πh11/2≈(νh11/2)2].

References[1] E.S. Paul, D.B. Fossan, K. Hauschild, I.M. Hibbert, H. Schnare, J.M. Sears, I. Thorslund,
R. Wadsworth, A.N. Wilson, and J.N. Wilson, J. Phys. G: Nucl. Part. Phys. 21 (1995) 995.
[2] E.S. Paul, D.B. Fossan, K. Hauschild, I.M. Hibbert, H. Schnare, J.M. Sears, I. Thorslund,
R. Wadsworth, A.N. Wilson, and J.N. Wilson, J. Phys. G: Nucl. Part. Phys. 22 (1996) 653.
[3] T. Komatsubara, K. Furuno, T. Hosoda, J. Mukai, T. Hayakawa, T. Morikawa, Y. Iwata, N. Kato,
J. Espino, J. Gascon, N. Gjørup, G.B. Hagemann, H.J. Jensen, D. Jerrestam, J. Nyberg, G. Sletten,
B. Cerderwall, P.O. Tjøm, Nucl. Phys. A 557 (1993) 419c.
[4] M.A. Quader, W.F. Piel, S. Vajda, W.A. Watson III, F.C. Yang, and D.B. Fossan, Phys. Rev. C 30
(1984) 1772.
[5] Harjeet Kaur, J. Goswamy, Jagbir Singh, A. Sharma, D. Mehta, Nirmal Singh, R.K. Bhowmik,
P.N. Trehan, Z. Phys. A 350 (1994) 183.
[6] Table of Isotopes, 8th Edition, Wiely, 1996.

- 37 -

2.10

Preliminary measurement of the g-factor of the second excited state in 165Ho

K. Furuno, K. Yamada, Y. Sasaki, S. Yokose, J. Y. Ma and T. Komatsubara
The experimetal data of the graound-state band of the nucleus 165 Ho are compiled in ref[1]. The
ground state has the spin-parity of I π = 7/2− . The spin-parities and the halﬂives are reported to
be I π = 9/2− and 20.0(4) ps for the ﬁrst exctied state at 94.7 keV; those of the second excited state
at 115.1 keV are I π = 11/2− and 12.8(6) ps. As regards nuclear g-factors, the value of g = 1.01(1)is given to the ground state. The g-factor of the ﬁrst excited state is measured to be g = 0.91(4)using Mössbauer eﬀect[2]. No other g-factor is reported for excited states.
We have measured the g-factors of the ﬁrst and the second excited state of 165 Ho by means of
ion-implanted time-integral perturbation method. The target consisted of 4 layers. A backing foil
was prepared by rolling a 3 µm iron foil(Fe) on a 2µm copper(Cu) foil. To obtain ﬁrm contact ofthese two foils, a thin indium(In) foil was inserted in between Fe and Cu foils. A 500 µg/cm2 thick
Ho layer was evaporated in vacuum onto the surface of the Fe foil. Another foil consisting of Ho andCu layers was made for the measurement of angular distribution without magnetic perturbation.
The excited states of 165 Ho were produced by Coulomb excitation with 32 S beam at energies of 68.8
and 90.1 MeV delivered by the 12UD tandem accelerator. Back scattered 32 S ions were detectedwith an annulat-type silicon surface-barrier detector. Gamma rays were observed with 4 Comptonsupprssed Ge detectors placed at angles of ±63.5◦ and ±116.5◦ with respect to the beam. A small
permanent magnet was used to magnetize the Fe foil. The magnitude of the ﬁeld produced by thismagnet was measued to be 0.084 T at the target position.
Precession angles were derived from the standard double-ratio method and slope factors. The
analysis of these data was performed according to the prescription described in ref[3]. In general,
Larmor precession angles due to the perturbation at higher levels must carefully be included in
the evaluation of the precession angle of a level of interest. We assumed that only two levels were
populated, since the Coulomb excitation was very weak for levels higher than the 3rd excited state.
With this assumption, the precession angles for the 1st and 2nd excited state can be written as
θ1 = (a g1 + b g2 )

µN
B τ1
h̄

and

θ2 = g2µN
B τ2 ,h̄

where g1 and g2 are the g-factors of the 1st and 2nd excitted states, τ1 and τ2 denote the mean
lifetime, B stands for the eﬀective magnetic ﬁeld, µN is nuclear magneton. The parameters of aand b are the weight of the populations of the two states, and are given bya=(N1 + N2 )τ1(N1 + N2 )τ1 + N2 τ2

and

b=

N 2 τ2.
(N1 + N2 )τ1 + N2 τ2

The populations of N1 and N2 were obtained from the intensities of the 94 and 115 keV γ rays.
Using the known value of g1 = 0.91 ± 0.04, we obtained the g-factor of the second excited state to
be g2 = 0.99 ± 0.20. The eﬀective magnetic ﬁeld B was also estimated to be 280 T. The value of theg-factor seems to be consistent with the prediction by the rotational model consisting of a deformed
rotor and one proton. The eﬀective magnetic ﬁeld is, however, much smaller than the hyperﬁne
ﬁeld of Ho implanted in iron. It might be due to the small applied ﬁeld of 0.084 T, which is inadequet for the saturation of the magnetization in the iorn foil. Further investivations are continued.
References[1] R.S. Firestone and V.S. Shirley, Table of Isotopes, 8th edition, vol 2.
[2] E. Gerdau, W. Räth and H. Winker, Zeit. Phys. 257(1972)29.
[3] O.Häusser, D. Ward and H. Andrews, Nucl. Instr. Meth. 169(1980)539.

- 38 -

2.11 Measurements of fusion cross sections in the reactions of 82Se + 138Ba
and 82Se + 134Ba
K.Sato, H.Ikezoe1, K.Nishio1 and S.Mitsuoka1
Evaporation residue (ER) cross-sections for the reactions of 82Se+138Ba and 82Se+134Ba were measured
by using 82Se beams from JAERI-tandem booster accelerator, where 138Ba has the neutron closed shell of
N=82 and 134Ba has no such neutron closed shell. Main purpose of these experiments is to investigate how
strongly the fusion process is affected by the nuclear shell structure. All evaporation residues produced in
the present fusion reactions are α-emitting nuclei and their energy and lifetimes of α-decay are known in
the literature [1]. Therefore we can identify each evaporation residue by detecting its α-decay energy andlifetime event by event.
The targets were made by sputtering a barium oxide on an thin aluminum foil of the thickness of 1.3µm.
The abundances of the mass 138 in a 138Ba target and of the mass 134 in a 134Ba target are ≈100% and73.5%, respectively. The thicknesses of the targets were measured by the energy loss of α particles (5.486
MeV) from a 241Am source, where the energy loss of α-particles in the barium target was calculated by thecode TRIM [2]. The measured thicknesses of 138Ba and 134Ba targets were 410 and 500 µg / cm2,
respectively. The targets were mounted on a rotating frame and were rotated during the beam irradiation toprevent breaking from heating by 82Se beam.
The evaporation residues emitted in beam direction were separated in-flight from the primary andscattered beams by the JAERI-recoil mass separator (JAERI-RMS). The separated ERs were implanted
into the double-sided position-sensitive strip detector (DPSD) mounted at the focal position of the
JAERI-RMS. The energy resolution of the DPSD was 75 KeV. The time-of-flight signal (TOF) of
incoming particles was obtained by two microchannel-plate detectors mounted in front of the DPSD andthe other 30 cm upstream the DPSD, respectively. The TOF signal was used to distinguish the α decay
events from the incoming particles. Moreover, the rough estimation of a mass number of the incoming
particles was obtained by using a two-dimensional spectrum of the energy of the incoming particles versus
the TOF signal. A silicon surface barrier detector was set at 45° with respect to the beam direction in thetarget chamber to measure the elastic scattering of the 82Se beam from the barium targets. The elastic
scattering events were used to determine the absolute values of the evaporation residues cross section.
We identified some specific channels by detecting ER-α1 and α1-α2 correlation chains, where α1 andα2 are the parent and daughter α decay event, respectively. The correlated event in position was identified
under the condition (∆X, ∆Y)=(0.6, 0.6) mm, where the ∆X and ∆Y are the position uncertainties in thehorizontal (x) and vertical (y) directions. Fig. 1 shows a two-dimensional spectrum of α particle energy
and the time interval between ER and α event, and Fig. 2 shows the two-dimensional spectrum of α1

1 Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai-Mura, Ibaraki 319-1195,
Japan- 39 -

energy versus α2 energy. In order to obtain the absolute cross sections of ERs, the transport efficiency of
the ER through the JAERI-RMS was estimated by the method described in Refs. [3,4]. The estimatedtransport efficiency for each ER was obtained by taking into account the charge fraction calculated by Ref.
[5]. The obtained transport efficiency was about 0.35 for the xn channel. Furthermore the probability ofdetecting the α decay of ER implanted in the DPSD was also estimated. The probability of full energy
absorption of α particle from 216 Th was 0.64, for example, at the beam energy of 323 MeV.

Figure1
104

τ(ms)

103

Th215

Ra213

Ac215
Th213

Fr213

Th214
Th216 Rn213

Ra212+Ra211
Ra210
Ra214
Ac213

102

Figure 1
Two-dimensional spectrum of theFr214

energy versus the detected time

Ra215

1

10

Ac216

interval between the α decay
Th217

Rn213

100

ER, whose position difference waswithin ∆X=∆Y=0.6mm

10-1
Ra215

Figure 2
Ac216

-2

10

7

8
Eα(MeV)

Two-dimensional matrix showing

9

the correlated α1-α2 chain between

Figure2parent and daughter α.
Th214
Th215

7

Th213
Th216

Boxes in Fig. 1 and in Fig. 2
indicate the eyes guide for eachTh217

E-d (MeV)

Ac210
Ac213
Ra206
Ac214

6.5

α-decay property of decay energy

Ac211

Eα and half lifetime T1/2. (Eα - 50

Ac212
Ac215

KeV ≤ E ≤ Eα + 50 KeV, T1/2 / 10
≤ τ ≤ T1/2 × 10)

Ac216

Ra207
Ra208
Ra210+Ra209

Ra212
Ra211
Ra214

6

particle and the position-correlated

7

7.5

8
8.5
E-p (MeV)- 40 -

99.5

The obtained evaporation residues cross sections (xn channels) for the reactions of 82Se+138Ba and82

Se+134Ba are shown in Fig. 3 as a function of c.m. energy determined in the middle of the target layer.

The error includes both statistical and systematical contribution. The systematical uncertainty was 40%
coming from the transport efficiency and charge distribution of ER.

Figure3100

Th217(3n)Th216(4n)10-2Th215(5n)Cross Section (mb)Th214+213(6n+7n)10-4

Th214+213(2n+3n)82

Se+138Ba3n(Th217)
4n(Th216)
5n(Th215)
6n+7n(Th214+213)
82
Se+134Ba
2n+3n(Th214+213)

10-6

180

190

200

210

220

230

240

250

260

Ec.m.(MeV)
Figure3
Evaporation residues cross sections of xn channels for 82Se+138Ba and 82Se+134Ba
reaction are shown together.

From Fig. 3, we can see that the 2n+3n cross sections in the reaction of 82 Se+134Ba are about a hundred
times smaller than the 3n cross sections in the reaction of 82 Se+138Ba at the low energy region Ecm < 210
MeV. It is noted that at the high-energy region Ecm > 220 MeV the small contamination of heavier masses- 41 -

138,137,136,135 of the present target (these contaminations are 5.26%, 1.94%, 4.03%, 15.24%,
respectively) comes into play in the 82 Se+134Ba experiment. The analysis is now proceeding by using thestatistical model code HIVAP [6] to simulate the deexcitation process of the excited compound nucleus.

References[1] R. B. Firestone et al.; Table of Isotopes 8th ed., New York, John Wiley, 1996
[2] The computer code to calculate the transport of ions in matter; see “The stopping and range of ions insolid” by J. F. Ziegler, J. P. Beersak, and U. Littnark, Pergamon Press, New York 1985
[3] K. Nishio, H. Ikezoe, S. Mitsuoka, and J. Lu, Phys. Rev. C 62, 014602(2000)[4] T. Kuzumaki, H. ikezoe, S. Mitsuoka, T. Ikuta, S. Hamada, Y. Nagame, I. Nishinaka, and O. hashimoto,Nucl. Instrum. Methods Phys. Res. A 437, 107(1999)[5] K. Shima, T. Ishihara, and T. Mikuno, Nucl. Instrum. Methods 200, 605[6] W. reisdorf and M. Schadel, Z. Phys. A 343, 47 (1992)- 42 -

2.12

Measurement of transient magnetic ﬁeld by using polarized
proton ionsT. Komatsubara, K. Sasa, T. Katabuchi, M. Yamaguchi, K. Kudo, K. Sawada, I. Masuno, T.
Iizuka, H. Oshima, Y.J. Ma, Y. Sasaki, K. Yamada, S. Yokose, M. Ishizuka, M. Yoshimoto, Y.
Tagishi, K. Furuno and T. Koyano 1
For measurments of nuclear magnetic moments a transition magnetic ﬁeld (TMF) is commonlyused to obtain certain spin precessions in a wide range of nuclear mass region. When ions passthrough a magnetized foil, nuclei of the ions feel strong magnetic ﬁeld which is known as thetransition magnetic ﬁeld. However, velocity dependence of the ﬁeld strength was studied only
for some narrow velocity regions by measuring a precession angle determined by intensities of
emitted gamma-rays. [1] In order to extend study of the TMF to higher velocity region, a newexperiment has been started by using polarized proton beam.
For detection of proton spin precessions caused by the applyed TMF in a magnetized iron foil,
spin directions were directly measured by use of nuclear reaction mechanism with polarized protonbeam. Two proton polarimeters were located up-stream and down-stream of the magnetized ironfoil. Both polarimeters consist of scattering targets of 12 C foil of 2mg/cm2 thick and proton
detectors at 45◦ in both left and right sides. Solid angles of proton detectors are 5.9 mstr for upstream counters and 8.3 mstr for down-stream counters for the scattering 12 C targets, respectively.
Incident beam energy was chosen to be 7.05 MeV to irradiate magnetized iron foil of 5µm thick.
The beam was introduced to the up-stream 12 C target which is located at a distance of 77 mm
up-stream of the iron foil. While a proton ion passed through the magnetized iron foil, directionof proton spin was rotated with degrading its kinetic energy to be 5.0 MeV by stopping power inthe foil. The down-stream 12 C polarimeter was installed at 60 mm from the magnetized iron foil
to measure the spin precession. In order to avoid multiple scattered protons, the down-stream
12
C target was covered by a copper window of 5 mm diameter.
The iron foil of 50 µm thick was prepared by annealing method at 970◦ C in 60 minutes underhydrogen atmosphere. A magnetic circuit was designed to apply suﬃcient extra magnetic ﬁeld tomagnetize the iron foil as shown in Fig.1. Eight small permanent magnets were located in bothside in the magnetic circuit. The permanent magnets were cylindrical shape of 1.6 mm high and
3 mm diameter. Magnetic ﬁeld was measured to be 2 kgauss on the surface. Fringing magnetic
ﬁeld was measured to be 100 gauss near the surface of the magnetized iron foil.
For the compensation of the inevitable fringing ﬁeld, reference experiments were carried out
by using copper foil. The other magnetic cicuit was prepared with a hole of 5mm diameter on
the radiating position of the magnetized iron foil. The copper foil with the same thickness as theion foil was covered on the hole so as to give the same stopping power for the proton beam. A
number of permanet magnets was adjusted to be six to create simulating the fringing magneticﬁeld.
In order to observe satulation of the magnetization of the iron foil, rf induction voltage wasmeasured with changing external magnetic ﬁeld. Two coils of 50 turns each were installed asshown in Fig.2. When an rf signal of 100kHz was appled to the excitation coil from an rf
oscillator, Vpp of induction voltage on the pickup coil was measured. From these results shownin Table 1, eight permanent magnets were found to be enough to magetize the iron foil.
Analyzing powers for 12 C(p,p) reaction were measured with this system at the incident energyof 7.05 MeV and degreaded energy of 5.0 MeV with not-magnetized foils. Incident spin directionof polarized proton was chosen to be perpendicular to the scattering plane. Polarization of proton
beam was measured to be 0.86 by quenching method. The analyzing powers were measured tobe -0.30 for the up-stream counter and -0.84 for the down-stream counter, respectively. These
1

Cryogenics Center- 43 -

results were consistent to a previous report.[2]For the measurement of the precession in the magnetized iron foil, two spin directions ofpolarized proton were chosen to be 0◦ and 180◦ those are parallel and anti-parallel to the beamaxis. Fast spin ﬂip operation system was used to change the proton spin and store individual
spectra with the same integrated bean current. As a result of the experiment, precession angles
are shown in Fig. 3. For the copper target, the precession angle is consistent to the fringing
magnetic ﬁeld. The extra precession observed for the iron target is derived by sum of the TMF
and its magetization ﬁeld. A time priod of the ﬂight passing through the iron foil is calculated
to be 1.45 [psec]. The corresponding strength of the magnetic ﬁeld can be account to be 9 ± 4[tesla] for the ﬂight time.

Table 1
Induction voltage measured by pickup coil while 100kHz rf signal applied
to excitation coil. An external magnetic ﬁeld was induced by permanent magnets.

no iron foil
no magnet with iron foil
8 magnets with iron foil
12 magnets with iron foil
16 magnets with iron foil

Induction voltage
Vpp [mV]
90
4900
380
315
260

Iron foil

Permanent magnet
Fig. 1. An iron foil and a magnetic circuit.

- 44 -

Oscilloscope

Oscillator

Iron foil

Fig. 2. An iron foil with exciation and pickup coils for the measurement of magnetization. Induction voltage was measured by changing a number of permanent magnets (which are notdrawn in this ﬁgure).

2001 Febrauary TMF experiment

Shift Angle [degree]

0.0
-0.2
-0.4
-0.6
-0.8

Fe

Cu

Cu

Fe

-B

-B

+B

+B

-1.0

Fig. 3. Spin precessions of polarized proton beam pass through a magnetized iron foil dependingon the direction of magnetization shown as +B and −B. Results for the copper foil arealso shown for simulating the eﬀect of the fringing magnetic ﬁeld.

References[1] M.P. Robinson, A.E. Stuchbery, E. Bezakova, S.M. Mullins, H.H. Bolotin, Nucl. Phys. A647
(1999) 175[2] S.J. Moss and W. Haeberli, Nucl. Phys. 72 (1965) 417- 45 -

3.1

Carbon KVV Auger electron emission from HOPG bombarded by fast protons

H. Kudo, K. Haruyama, T. Kinoshita, T. Azuma1 , S. Ishii, S. Seki2
We have continued the studies of ion-induced Auger spectra under the condition that theAuger yields depend on the layered structure of the target material, so that the commonly used
macroscopic model of the Auger yield must be modiﬁed. Since Auger peaks are superposedon the continuum energy spectrum, precise analysis of the Auger yield requires knowledge on
the continuum yield which results mainly from the binary-encounter processes [1]. Ion-induced
electron spectroscopy at 180◦ with respect to the beam direction has a characteristic feature thatthe continuum energy spectrum is independent of the tilt angle of the target surface [2, 3]. The
180◦ electron spectroscopy therefore allows direct comparison of the electron spectra measured
under oblique incidence conditions on the surface.
The sample we have used is highly-oriented pyrolytic graphite (HOPG), which has a layer
structure of hexagon network of carbon atoms. The bond length in the network is 1.42 Å andthe layer spacing is 3.35 Å. In the 180◦ electron spectroscopy, we observe carbon KVV Auger
electrons of kinetic energy EA = 260 eV, which are emitted from the surface while bombarded
by fast ions. When the HOPG surface is oblique to the ion beam, i.e., to the spectrometer
direction, the measured Auger electrons produced inside the target move towards the surface andare refracted to 180◦ by the work function of φ 5 eV.
The Auger peak height can commonly be related to the mean free path for inelastic scattering
λ, which determines the attenuation of the elastically scattered Auger yield as exp (−z/λ), wherez is the escape length of the electron. For incident direction of the ion beam with an angle θ fromthe HOPG surface, the relative intensity of the Auger yield Y (θ) is written

Y (θ) =

∞

1
−nd
−t
)
exp (
)
exp (
sin θ
λ sin θ2 n=0
λ sin θ1



=



−1
1
t
d
exp (−) 1 − exp (−
)
,
sin θ
λ sin θ2
λ sin θ1

(1)

where θ1 is related to θ by cos θ1 = (1 − eφ/EA )1/2 cos θ, and t is the eﬀective thickness of theelectron distribution above the HOPG surface. θ2 is the average emission angle at the surface,which is approximately given by (θ1 +θ)/2. The term 1/ sin θ represents geometrical enhancementof the irradiated surface area. It is also assumed that the Auger electrons are produced at theatomic sites.
Figure 1 shows the values of R = Y (θ)/Y (90◦ ) as a function of λ, calculated from eq.(1), forθ = 5.7 and 10◦ , which correspond to θ1 = 9.8 and 12.8◦, respectively. In this case, the values of t
have been assumed to be 0.6d and d. Generally, R ≥ 0 for t = 0. Also, R approaches sin θ1 / sin θas λ → ∞, which corresponds to the macroscopic model of the Auger peak height.
In the experiments, a (0001) surface of HOPG has been prepared by peeling of the surface
layer by an adhesive tape. The observations by an atomic force microscope in air assured thatthe fresh (0001) surface is atomically ﬂat except for steps of a few monolayers, which are apartfrom each other by the order of a micronmeter. The HOPG samples were bombarded by a 1 MeV
H+ beam which were obtained from Tandetron at UTTAC. Under the present experimental
conditions, the critical angle of HOPG(0001) planar channeling (∼0.42◦ ) is much less than thevalues of θ noted earlier so that the specular reﬂection of the ions is unexpected to occur. The
1
2

Tokyo Metropolitan Univ.
SSL Tsukuba- 46 -

1.4

t=0.6d

1.2
1.0

θ=10°
θ=5.7°

t=d

R

0.8
0.6

θ=10°

0.4

θ=5.7°

0

0

2

4

8

10



0.2
6

(Å)

12

14

16

18

Figure 1: Calculated R as a function of λ. θ is the Auger emission angle relative to the HOPG
surface.

electron measurements have been carried out using the 45◦ parallel-plate spectrometer of the
double deﬂection type under the pressure of ∼3×10−7 Pa. Of course, the scattering eﬀect of
the emitted electrons by the steps should be minimized for observations at 180◦ . The measured

4000
HOPG

θ
H+ beam

3000

Yield (counts)

θ = 90°θ = 10°2000

Y(θ =10°)θ = 5.7°

1000

0
100

150

200

250

300

350

Electron energy (eV)Figure 2: Electron energy spectra for θ = 5.7 and 10◦ , measured for HOPG bombarded by 1 MeV
H+ . The relative energy resolution of the spectrometer is ∼1%.
electron spectra for θ = 5.7, 10, and 90◦ are shown in Fig. 2. The three spectra are plotted after
they are normalized so that the continuum yields at 300–350 eV are equal. This assumption seems
valid for the 180◦ electron spectroscopy, mentioned earlier. Furthermore, it is anticiaped that thesmooth continuum spectrum should be less inﬂuenced by the scattering by valence electrons above
the surface, noted earlier.
We see in Fig. 2 that the normalized Auger peak becomes lower with decreasing θ. The
experimental values of R for θ = 5.7 and 10◦ are 0.52±0.03 and 0.68±0.03, respectively. These
values can be compared to the calculated results, shown in Fig. 1, taking into account that- 47 -

λ 10 Å [4]. In this analysis, t may be regarded as an adjusting parameter. The observed valuesof R can be well reproduced for t 0.8d = 2.7 Å. It should be noted that if the production sites
of KVV Auger electrons are uniformly distributed in HOPG, i.e., not localized near the carbon
nuclei, t = 0 must be assumed in eq. (1). In this case, R(θ) increases with decreasing θ from 90◦ ,contrary to the observation. The experimental results therefore indicate that the KVV Auger
production sites are localized near the carbon nuclei.
The analysis model used here is rather qualitative. However, the essential aspects of thephenomenon have been revealed from the present pexeriments, i.e.,• The degraded KVV Auger peaks for emission in the oblique directions are due to the elastic
and inelastic collisions with valence electrons distributed on the surface. Also, the Auger
peak height reﬂects the layered structure of HOPG.
• Certainly, R ≥ 1 for any θ if the Auger electrons are produced unformly in HOPG. However,
the experiments indicate that R < 1. Detailed analysis of the experimental results should
provide location of the preferential production sites of the valence Auger electrons in thelayered structure.

References[1] M. E. Rudd, Y. -K. Kim, D. H. Madison, T. J. Gay, Rev. Mod. Phys. 64 (1992) 441.
[2] H. Kudo, A. Tanabe, T. Ishihara, S. Seki, Y. Aoki, S. Yamamoto, P. Goppelt-Langer, H.
Takeshita, and H. Naramoto, Nucl. Instr. and Meth. B 115 (1996) 125, and references therein.
[3] H. Kudo, Ion-Induced Electron Emission from Crystalline Solids, in press as a volume of’Springer Tracts in Modern Physics’, Springer-Verlag, Heidelberg, 2001.
[4] M. P. Seah, W. A. Dench, Surf. Interface Anal. 1 (1979) 2.

- 48 -

3.2

Ion-induced electron emission from damaged Si crystals

H. Kudo, M. Ohira, T. Kinoshita, K. Takeda, S. Seki1
Ion-induced electron spectroscopy in conjunction with ion channeling can be successfully used
to structural analysis of crystalline solids under low beam dose conditions [1, 2]. This analysis
technique provides structural information from the binary-encounter electron yield measured at180◦ with respect to the beam direction. The purpose of the present expriments is to study an
increase of the channeling electron yield due to the lattice disorder, whose depth distribution
can be characterized by Rutherford backscattering spectroscopy (RBS) [3]. This should allow abetter check of the analysis model.

2500

2500

360keV Ar+, 1x1014/cm2

360keV Ar+, 1x1015/cm2
2000

Yield (counts)

Yield (counts)

2000

1500

Random1000

1500

Random
1000

<100>

<100>
500

500

<100> undamaged
0

100

200

<100> undamaged
0

300

100

200

300

Ion energy (channel number)Ion energy (channel number)

Figure 1: RBS spectra of damaged Si, measured with 2 MeV He+ at 165◦ .
Si crystals were damaged by bombardment of 360 keV Ar+ with beam doses of 1 × 1014 cm−2
and 1 × 1015 cm−2 . Figure 1 shows RBS spectra measured with 2 MeV He+ at a backward angleof 165◦ . For the damaged Si, the <100> channeling spectra clearly shows enhancement of the
RBS yield, which results from the damaged layer ranging from the surface to a depth of ∼7000 Å,according to the energy-depth conversion using the ion stopping power.
The electron measurements have been carried out using 40 MeV O5+ and 56 MeV O8+ at
UTTAC. The ratios of <100> to random (nonchanneling) electron yield W have been measured
at 6.15 and 9.75 keV for 40 MeV O5+ and 56 MeV O8+ , respectively. These electron energies arehigher than the corresponding values of the binary-encounter peak energies (5.43 and 7.61 keV,
respectively), so that the measured yields stem mainly from Si inner-shell (mainly L-shell in thiscase) electrons. The values of W obtained are shown in Table 1.
For the beam dose of 1 × 1015 Ar/cm2 , the electron yield is close to unity. This can be
accounted for by the eﬀective escape depth of ±2000 Å, which has been determined from theelectron measurements using overlayered Si crystals [2]. Actually, the RBS spectrum indicatesthat the Si crystal is seriously damaged from the surface to a depth of at least ±2000 Å. For
the beam dose of 1 × 1014 Ar/cm2 , we have determined the values of z where W is equal to theintegrated RBS yield Y(z), given by
Y(z) =

 z

 z

Yc dz /
0

Yr dz,(1)0

where Yc and Yr are the RBS yield for the channeling and random cases at z, respectively. The
results obtained are 3800±230 and 3300±180 Å for 40 MeV O5+ and 56 MeV O8+ , respectively.
1

SSL Tsukuba- 49 -

Table 1: Experimental values of W for damaged Si. The values of the electron energies measured
are noted in the text.
Projectile

1 × 1014 Ar/cm2

1 × 1015 Ar/cm2

40 MeV O5+

0.264±0.011

0.949±0.038

56 MeV O8+

0.214±0.009—

These values are greater than the corresponding eﬀective escape depths by a factor of 1.5–1.8.
The discrepancy is probably due to the insuﬃcient depth resolution of the RBS yield for thepresent analysis. High resolution RBS is needed for detailed comparison between the electron
and RBS data.

References[1] H. Kudo, T. Kumaki, K. Haruyama, Y. Tsukamoto, S. Seki, H. Naramoto, Nucl. Instrum.
& Methods B174 (2001) 512.
[2] H. Kudo, Ion-Induced Electron Emission from Crystalline Solids, in press as a volume of’Springer Tracts in Modern Physics’, Springer-Verlag, Heidelberg, 2001.
[3] M. Ohira, Master thesis, University of Tsukuba, 2001.

- 50 -

3.3

New family member of active center created by multi-MeV ion
bombardment of silica glass

Koichi Awazu1, Satoshi Ishii and Kunihiro Shima
1. Introduction
In most insulators, the passage of swift (multi-MeV) heavy ions creates a heavily damaged, cylindricalzone known as the latent track. The majority of studies of latent tracks during the last 30 years or so were
aimed at understanding the formation mechanism and a number of models have been proposed. Since theintroduction rates of point defects due to nuclear collisions along the ion trajectory is far too small to
explain the appearance of latent tracks, it is clear that the electronic stopping of the ions is responsible forthe track formation. As a result of this electronic stopping, the wake of the ion contains a high density ofenergetic electrons. The proposed models differ in how, and how fast, these exited electrons transfer theirenergy to the atomic network. In the thermal spike model 1-3, the energy is rapidly and locally thermalized,
leading to short-lived but extremely high temperatures along the ion track. In the ion spike or Coulomb
explosion model 4,5, the ion track is denuded of electrons long enough for the mutual Coulombic repulsionof neighbouring atoms to occur. Hybrid models have also been proposed 6,7. However, all these models
focus on the very early stages of track formation and give little information on the expected atomic
structure of the latent tracks. Moreover, the origin and structure of the defects responsible for the enhanced
etch rate of the latent tracks have not been identified. Our experimental work described in this reportattempts to improve our understanding of these latter issues by approaching the problem from a number ofdifferent angles correlating changes in infrared absorption with the etching enhancement in latent tracks.
Amorphous SiO2 (hereafter a- SiO2) has often been chosen as a target for ion implantation because thephysical and structural properties of a- SiO2 are well known 8. In general, microscopic defects in a- SiO2 as
introduced by ion implantation can be classified in two types: paramagnetic centers on one hand, andnon-stoichiometric defects such as oxygen deficient or excess centers on the other.
Macroscopic changes of a-SiO2 resulting from radiation have been also reported by many authors. Bateset al.9 reported that the densities of a-SiO2 and α-quartz increased and decreased, respectively, upon neutron
irradiation and that both materials stabilized at a nearly identical density of ~2.27 g/cm3 after irradiation
with 5×1019n/cm2 or more. Hiraiwa et al.10 reported a frequency shift of the infrared (IR) absorption peak(ω4) induced by ion implantation. This peak is associated with the asymmetric stretching mode of an
oxygen atom in the Si-O-Si inter-tetrahedral bridge. They also reported that the shift ∆ω of the frequency
saturated at around –30cm-1 when the nuclear-deposited energy reached 3.4×1023eV/cm3, which is equal to
the total Si-O bonding energy (3.8eV) in a unit volume of a-SiO2.
The subject of the present work is to determine the defect(s) underlying the creation of individual conic
holes in a-SiO2. It was observed that a number of defect structures make up the latent track. We observed
SiO4 tetrahedra composed of planar three member rings, the E’ center, and the oxygen deficient center inthe latent tracks. We proposed that the planar three- and four member rings in latent tracks were responsible
for the enhanced etching rate. Neither the E’ center nor the oxygen deficient center exhibit any influence on
the etching rate.
2. Experimental-4
Ion bombardment was performed at room temperature and at a residual pressure below 1×10+ Pa. A 6
MV+ tandem accelerator
in +Université de6+Montréal was employed
for irradiation with 10 MeV H , 15 MeV+
6+He , 2 MeV Li , 4 MeV C , 30 MeV Si and 35 MeV Se . We also used a 12 MV tandem accelerator
in11+
the Tandem
Accelerator12+Center of Universityof Tsukuba (UTTAC) for irradiation with 120 MeV Br , 127
11+13+conic holes that
MeV Br , 98 MeV I and 112 MeV I . In order to avoid overlap of the individual
7-2appear after chemical etching of latent tracks, very low ion fluences (typically 1×10 cm ) are required. This
was achieved by diffusing the ion beam with either a C foil or an Au foil in either forward or
back-scattering geometry. A variety of a-SiO2 was used for these studies. Type III a-SiO2 plates of 2 mm
thickness, which contain 1000 ppm OH, were used for direct observation of latent tracks. Amorphous SiO2
films 193 nm thick were thermally grown on (100) silicon wafers in O2 atmosphere at 1000°C. The silicon
1

Photonic Research Institute, National Institute of Advanced Industrial Science and Technology,1-1-1 Umezono, Tsukuba 305-8568,
Japan- 51 -

wafers used in the present experiment were prepared by the floating-zone method with resistance ~3000 Ω
cm. These wafers of 200µm thickness were chemically polished on one side only in order to eliminate IR
multiple interference effects. IR absorption was measured with a Fourier transform IR (FT-IR)
spectrophotometer using light at normal incidence. Visible individual holes were created from the irradiatedsamples by chemical etching with 48% hydrofluoric (HF) acid and were observed with a scanning electron
microscopy (SEM) at an angle 45° from electron incidence.

0.2

Absorbance

0.15

1078cm-1
1×10 cm11-2

1 ×10 cm
12

virginFig.1 IR absorption spectra of an a- SiO2
film 193nm thick bombarded with I ionsataccumulated
doses
1×1011cm-2,
12
-2
13
-2
1×10 cm and 1×10 cm . Solid line
shows the spectrum of the virgin sample.

1044cm-1

-2

0.1

0.05

1×1013cm -2
ω

0
1300

1200

4

1100
1000
900
Wavenumber (cm -1)

ω

3

800

700

1080

1070

Br

-1

ω4 frequency (cm )

H He

Se
1060

I
Si

Li

C

1050

1040
1011

1012

1013
1014
-2
Dose (cm )

1015

1016

Fig.2 Frequency at an absorption
maximum of the ω4 band against dose.
10MeV H; open squares, 15MeV He;
open triangles, 2MeV Li; closed squares,
4MeV C; closed circles, 30MeV Si;
closed diamonds, 35MeV Se; closed andreversed triangles, 67MeV Br; closed
triangles and 80MeV I; crosses. All lines
are guides for the eyes. Open circles
correspond to the bond energy of Si-O
which was obtained from the electronic
stopping power of each ions multipliedby dose.

3. Results
withFig. 1 presents IR absorption spectra of a 193 nm thick a-SiO2 film before and after bombardment-1
80 MeV-1 I ions. The unirradiated film shows two first order features in the IR absorption 1078 cm and at
Irradiation
introduces a shift in opposite directions:
805 cm , which were labelled ω4 and ω3, respectively.
-1-1-1
the frequencyofω
decreases
from
1078
cm
to
1044cmwhereasthat of ω3 increases from 807cm to4-1822cm .
The evolution of the position of the peak labelled ω4 for a variety of ions and as a function of ion dose isshown Fig. 2. The following ion/energy combinations are shown: 10 MeV H, 15 MeV He, 2 MeV Li, 4
MeV C, 30 MeV Si, 35 MeV Se, 67 MeV Br and 80 MeV
I.-2 Peak shift was not observed for either 10
16
MeV H ions or 15 MeV He ions in the -1dose region of 10 cm and lower. For all other ions, the frequency
ω4 decreased and saturated at 1044 cm with increase of dose. The ion dose where saturation is reached isvery different for the different ions, spanning three orders of magnitude. Otherwise, the behaviour of thefrequency shift as a function of ion dose is similar for all combinations with only a factor of 12 to 15
between the dose required to initiate a shift and that to saturate it. In order to facilitate comparison of thedifferent ion / energy combinations, points of equal deposited energy
have been
identified. The open circles
23
3
on each curve in Fig. 2 correspond to a deposited energy ~3.4×10 eV/cm , which amounts to a depositedenergy density approximately equal to the total Si-O bonding energy ~3.8 eV in a unit volume of a-SiO2.10
MDDZ = 0.65/{(10-7Rd)2π}. Peak shifts of the frequency ω4 at the MDDZ were estimated from Fig.2.
- 52 -

Fig.3 Diameter of holes introduced by bombardment of 80MeV I ions followed by etching vs shift of thefrequency 4 at the minimum dose to cover the surface with damaged zones (MDDZ). Chemical signals forelements written near squares identify the bombarding ions. Circles present the relationship between
diameter of holes introduced by bombardment of 80MeV I ions followed by etching and shift of thefrequency ω4 at the MDDZ with the annealing temperature as a parameter. Temperatures for eachexperiment are presented near each point.
150
Hole diameter (arbitrary unit)

I
400oC

100

Se

Si

50

450oC
500oC
Br

600oC
C Li

0
-35 -30 -25 -20 -15 -10 -5
IR peak shift (cm -1)

Rd (nm)MDDZ (1012cm-2)
ω4 peak shift (cm-1)
Hole diameter(arbitary unite)0

Fig.3 Diameter of holes introduced bybombardment of 80MeV I ions followed by etchingvs shift of the frequency ω4 at the minimum dose tocover the surface with damaged zones (MDDZ).
Chemical signals for elements written near squares
identify the bombarding ions. Circles present therelationship between diameter of holes introducedby bombardment of 80MeV I ions followed byetching and shift of the frequency ω4 at the MDDZ
with the annealing temperature as a parameter.
Temperatures for each experiment are presented
near each point.

Li
1.5
9.8
0

C
1.9
8.0
-1

Si
2.8
6
-5

Se
2.5
5.5
-24

Br
3.4
2.7
-25

I
2.7
5.1
-34

0

0

20

92

96

145

Table 2MeV Li, 4meV C, 30MeV Si, 35MeV Se, 78MeV Br and 78MeV I. Rd value isthe radius of a cylinder which absorbs 65% of the incident energy. The minimum doseto cover the surface with damaged zones (MDDZ) was estimated with the formula.

4. Discussion
The data shown in the preceding sections covers the effects of a wide range of ion species, energies, andfluences on the structure of a-SiO2. To compare one ion mass with another, some scaling of the ion dosewould be required. In particular, we would like to compare measurements at a fluence where theindividual cylinders are just beginning to overlap. This can be estimated using an analytical formula11 forthe radial profile of the spatial energy deposition. Once this radial damage profile is known, the radius Rd of
the damage cylinder is estimated at that which contains 65% of the incident energy. From Rd, the minimum
dose to cover the surface with damaged zones (MDDZ) was estimated with the formula,
MDDZ (cm-2) = 0.65/{(10-7Rd)2π}(1).

Values for Rd and MDDZ for each of the ions used are summarized in Table, as well as frequencies ω4 at
MDDZ estimated from the corresponding curves in Fig.2. Heavy ions such as Se, Br and I, which upon
etching introduce clear individual holes on a-SiO2, are seen to introduce a large shift of ω4 at MDDZ. This
would imply that even the passage of a single Se, Br or I ion creates a latent track where the shift of thefrequency ω4 is at least -20 cm-1.
Using the data from Table, we now know which doses should be compared and thus re-plotted (as squaresymbols) the measured diameter of etched holes against the shift of ω4, for all projectiles but in each case at
MDDZ (Fig.3). As well, these data are compared directly with the annealing results of 80 MeV I irradiatedsamples: the circles show the diameter of holes made by 80 MeV I irradiation, annealing, and etching
against the shift of ω4. Annealing was performed prior to etching and IR absorption measurement. A- 53 -

-1

12

-2

maximum shift in ω4 (at MMDZ) of -34 cm could be obtained by bombardment with 5×10 cm 80 MeV
I ions. An increase of ω4 and a decrease of the hole diameter are simultaneously observed with increasing
annealing temperature. Clearly, the circles (annealing) fall on the same line as the squares (different ion
mass) which strongly implies that the shift of ω4 in the latent tracks is correlated with the etching efficiencyof those tracks. Etching efficiency is strongly correlated the the shift of the frequency ω4.
We will attempt to identify a structural model for the changes in silica induced by swift heavy ions thatgive rise to the observed shift in ω4. The basic building block of amorphous silica is the SiO4 tetrahedron
with an O-Si-O bond angle of 109.5°; these rigid tetrahedra are then placed together in 6 to 9 member
rings.12 Molecular orbital calculations indicate that the bond energy is minimized for an inter-tetrahedral,
Si-O-Si bridging bond angle θ ~144° and that for 120°≤ θ ≤ 180° there is only a weak variation in thebond energy with angle. The central frequency of the IR absorption peak ω4 depends on the bond angle θand, as a good approximation, is given by:ω4 = a[2(α sin2θ/ 2 + β cos2θ/2)/m]1/2(2)

where α and β are the central and non-central force constants, m is the mass of the oxygen atom, and θ-12isthe bridging bond angle of Si-O-Si.
If m is in kg, a in N m-1, and with a multiplying constant 5.305×10 ,-1
this equation yields ω4 in cm . A compilation of data on materials where θ has been measured directly bysome method such as electron or X-ray diffraction shows that to a very good approximation, for θ ≤ 150°,
α = 582 N m-1 and β = 264 N m-1. Eq. (2) then enables us, with some confidence,
to estimate
Si-O-Si bond-1
-1angles from measured IR absorption frequencies. A shift in ω4 from 1078 cm to 1041 cm would imply adecrease in Si-O-Si bond angle from 144° to 129°. The Si-O-Si bond angle in a planar three member rings
was estimated at 130.5°. 14 Therefore, one candidate to explain such a strong reduction of Si-O-Si bondangle would be the reduction of ring size from six member rings to planar three member rings.
We now recall that the open circles in Fig.2 denote the ion dose where the deposited energy reaches
3.4×1023eV/cm3, which is approximately equal to the total Si-O bonding energy (3.8eV) in a unit volume
of a-SiO2. The deposited energy was calculated from the electronic stopping power, multiplied by dose.
The position of the open circles do not correspond with the starting point of the frequency shift of ω4. For
example, the peak shift started when the absorbed energy exceeded the total Si-O bonding energy for 2MeV
Li ions. In contrast, the peak shift was over and saturated when the absorbed energy reached to the total
Si-O bonding energy for 80MeV I ions. This suggests that the peak shift is not related to the scission of
Si-O bonds. Details were reported in references 15 and 16.
5. Summary
In summary, the defect structure of ion tracks in a-SiO2 created by swift heavy ions has been studied by
IR absorption, XPS and ESR. These techniques showed how the ring statistics and the number of bondscissions changed with ion dose, and that these two phenomena behaved differently. The ion dose
dependence of the etching rate enhancement correlated with the changes in ring statistics but not with bondscission or oxygen deficiency. It is concluded, therefore, that the major reason for the fast etch rate in thelatent track is the generation of planar three- and four-member rings. These planar three- and four-member
rings are likely introduced by a process of flash heating and quenching following the passage of a swift
heavy ion.

References[1] G. Bonfiglioli, A. Ferro and A. Monjoni, J. Appl. Phys., 32, 2499 (1961).
[2] Meftah, F. Brisard, J.M.Costantini, E. Dooryhee, M.Hage-Ali, M.Hervieu, J.P. Stoquert, F. Studer andM. Toulemonde, Phys. Rev. B 49, 12457 (1994).
[3] M. Toulemonde, J.M. Costantini, Ch. Dufour, A. Meftah, E. Paumier and F. Studer, Nucl. Inst. and Meth.
In Phys. Res., B 116, 37 (1996).
[4] R.L. Fleischer, MRS Bulletin, 20, 17 (1995).
[5] R.L. Fleischer, P.B. Price and R.M. Walker , Nuclear tracks in solids – principles & applications,
University of California Press, Berkley,1975)[6] E. Dartyge and P. Sigmund, Phys. Rev. B32, 5429 (1985).
[7] K. Tanimura and N. Itho, Phys. Rev. B 46, 14 362 (1992).
[8] G.W. Arnold, J. Non-Cryst. Solids, 179, 288, (1994).

- 54 -

[9] J.B. Bates, R.W. Hendricks and L.B. Shaffer, J. Chem. Phys., 61, 4163 (1974).
[10]
A. Hiraiwa, H. Usui and K. Yagi, Appl. Phys. Lett., 54, 1106 (1989).
[11]
M.P.R. Waligorski, R.N. Hamm and R. Katz, Nucl. Tracks Radiat. Meas., 11, 309 (1986).
[12]
C.E. Jesurum, V. Pulim and L.W. Hobbs, Nucl. Inst. and Meth. In Phys. Res., B 141, 25 (1998).
[13]
P.N. Sen and M.F. Thorpe, Phys. Rev. B15, 4030 (1977).
[14]
F.L. Galeener, Solid Stat. Commun., 44, 1037 (1982).
[15]
K.Awazu, S.Ishii, K.Shima, S.Roorda, J.L.Brebner, Phys.Rev. B, 62, 3689 (2000).
[16]
K.Awazu, S.Ishii, K.Shima, Jpn. J. Appl. Phys., 39, 7058 (2000).

- 55 -

3.4

Foil thickness for ions attaining charge equilibrium

K.Shima
Energetic ions after penetration in matter change their charge fractions until projectile charge states become
equilibrated at certain penetration depth. This charge equilibrium thickness, Teq, is very important in various
fields where ion beam interaction is involved. Actually, in most cases, there has been no way to estimate the Teqvalues. One reason for this is because non-equilibrium charge distribution data are much less than equilibrium
charge distribution data, and hence the systematic trend of Teq on projectile atomic number Z1, target atomic
number Z2, and ion energy E is little known. Particularly, the dependence of Teq on Z2 in solid targets has little
been investigated except for a few combination of Z1+Z2 [1]. On the other hand, theoretical study of Teq from theview of collision process is also limited [2] since many parameters involved in charge exchange process make theinvestigation complicated.
In order to serve as a milestone for the systematic understanding of Teq in matter, the dependence of Teq on
Z2 has been investigated for the incidence of 95 MeV F ions passing through the solid target foils of C, Al, Cu,
Ag and Au. The reason to have adopted such swift F ions as projectiles is that the dominant charge states
involved in the collision are limited to F9+ and F8+,and hence, charge exchange process is rather
simplified. For this purpose, charge distribution of
F ions was measured at the foil thickness region
where

projectile

chargestatesvary

fromnon-equilibrium to equilibrium.
Obtained mean charges, qb , of ions after
passage through foils are plotted in Fig.1as afunction of target thickness x. A noticeable result isthat the charge equilibrium thickness Teq is strongly
dependent on Z2 , i.e., the Teq values are higher forions passing through a foil with lower Z2. When thetarget thickness is expressed in units of atoms/cm2,
the Teq value of 95 MeV F ions in C foil is about oneorder higher than that of F ions in Au.
From observed data of charge fractions of ionsas a function of foil thickness, charge exchange crosssections have been estimated by means of two
different ways of curve fitting method and slope
method. The σqk values deduced from slope method
are charge exchange cross sections in single collision at

Fig.1. Observed values of mean charges, qb , of 95 MeV F

very small penetration depth, meanwhile those fromions after passage through C, Al, Cu, Ag and Au foils as a

curve fitting method are cross sections of ions fromfunction of foil thickness in units of atoms/cm2.

- 56 -

charge non-equilibrium to equilibrium penetration region. The fact that the σqk values of these two methods are ingood agreement, suggests that the ionic charge exchange process in carbon foil is dominated with step-by-stepsingle electron transfer where the excited state of ions during the collision is of minor contribution. In other word,
the collision process of highly charged 95 MeV F ion in carbon is rather simple, and the effect of residual
excitation collision may be of minor contribution to charge exchange process. The reason is as follows.
In the analysis of charge exchange of 9.6 to 38 MeV F ions in carbon foils, Nielsen et al. adopted
3-component model in which the probability of ions bearing L-shell electrons was taken into account for eachcomponent of projectile double-, single- and no-K-vacancy states. One of the solutions they obtained was thatthe mean numbers of L-shell electrons attached to an ion of single-K-vacancy state are 1.55 for 9.5 MeV F ionsand 0.28 for 38 MeV F ions inside the carbon foil. Since these numbers should rapidly tend to decrease withincreasing collision energy, 95 MeV F ions inside the carbon foil may be considered to be mostly in the groundstate.
In the present collisions, charge states of F9+ and F8+ are mainly correlated with the charge exchange process,and so, equilibrium mean charges are around 8.5 (see Fig.1). For simplicity, if we assume that the collision isdominated by F9+ and F8+ ions, then, the solution of rate equation is given by,
F9(x) = (σ89 /σT){1-exp(- σT x )} ,(1)

F8(x) = 1 - F9(x) ,(2)σT = σ89 + σ98 ,(3)for the incidence of F at x=0 . Generally, the total cross section σT is higher for higher Z2. On the other hand,
8+charge equilibrium thickness Teq is subject to the variation of the function exp(-σT x ). Hence, Teq values are
smaller for the higher Z2. In fact, if we list the σ89 , σ98 Teq and σT Teq values of observed at present in table 1,
the σT Teq values are almost indifferent to Z2.
Above mentioned fact indicates that in a very simple collision where only two charge states are involved incharge changing process, the magnitude of the sum of electron loss and electron capture cross sections
determines the magnitude of charge equilibrium depth Teq.
For ions whose degree of charge states, qb/Z1 , is not so high as that of 95 MeV F ions, the number of charge
states mainly involved in charge exchange process would be more than two. In that case, the solution of the rateequation becomes a little complicated function of charge exchange cross sections. However, on the analogy of
95 MeV F+Z2 collisions, we can easily estimate that, the Teq values of ions in matter would be dominated withthe charge exchange cross sections of ions around the mean charge states in matter. In order to be able topredict reliable values of Teq for any given collisions of Z1+Z2, more accurate cross sections as well as
experimental data compilation are necessary.
Experimental reports on the Z2-dependence of Teq are much less compared with reports on Teq of Z1 + C foil
collision. As is clear from above description, this is because, equilibrium thickness Teq of ions in C foil is larger
than that in other foils with higher Z2 , and hence, the observation of the former collision is easier. In this work,by using thin self-supporting foils of Z2=6 to 79, the Teq values have first been obtained over the wide range of
Z2.

- 57 -

Table 1. Charge exchange cross sections σ89 and σ98 , charge equilibrium thickness
Teq , and the product σT Teq = (σ89 + σ98 ) Teq for 95 MeV F ions colliding with foilsof C, Al, Cu, Ag and Au.
foil
σ89 (10-18 cm2)
C
0.7±0.15Al
2.8±0.3
Cu
6.0±0.8Ag
8.0±1.4
Au
10±1.8σ98 (10-18 cm2)
0.4±0.1
1.5±0.3
3.5±0.4
6.0±1.1
8.0±1.9

Teq (1018atoms/cm2)
3.0±0.5
1.0±0.2
0.50±0.2
0.30±0.08
0.24±0.06

σT Teq
3.3
4.3
4.7
4.2
4.3

References[1] C.S.Sofield, N.E.B.Cowern, J.Draper, L.Bridwell, J.M.Freeman, C.J.Woods andM.Spencer-Harper, Nucl. Instrum. Meth. 170, 257 (1980).
[2] V.P.Zaikov, E.A.Kral’kina, N.F.Vorobjev, I.S.Dmitriev, V.S.Nikolaev andYa.A.Teplova, Nucl. Instrum. Meth. B5, 10 (1984).

- 58 -

3.5

Difference of the diffusion and trapping of the implanted deuterons inmetals between the single crystal and poly-crystal

N. Kawachi, T. Katabuchi, M. Yamaguchi, M. Imon, and Y. Tagishi
We have proposed the method to measure the density of the implanted deuterons in solidmaterials during the deuteron implantation [1,2]. In this method, the density of the implanted deuterons ismeasured by detecting the emitted protons from the nuclear reaction 2H(d,p)3H between the implanted
deuterons and the incident deuteron beam. In the present work, the D- ion beam with an energy of 90 keV
was used as an implanted beam and at the same time as a probe beam. The temperature of the target
materials was kept constantly during the implantation, by using a thermoelectric cooler. The emitted
protons from the nuclear reaction 2H(d,p)3H were detected with a silicon solid-state detector. We measured
the time-dependence of the yield of the emitted protons as a function of time from the beginning of thebombardment. The time-dependence of the proton yield reflects diffusion and trapping of the implanted
deuterons in the target materials.
Experimental results were obtained for various metal targets (Al, Ti, Ni, Cu, Pd, Ta, Pt and Au)
at various temperatures. A drastic difference of the time-dependence of the proton yield was observed
between the single crystal and poly-crystal of Ta. On the other hand, no difference was observed in case of
those in Cu (Fig. 1). Further, the depth profiles of the implanted deuterons are able to be obtained from theenergy spectrum of the emitted protons by using the kinematics of the 2H(d,p)3H reaction. Further
systematic studies are now in progress.

Single Crystal and Poly-crystal Targets

Yield (counts)

250

Fig.1.

200

Proton yield from the 2H(d,p)3H reactions

during implantation of D- ions in Ta and Cu (single
150

crystal and poly-crystal) at room temperature.
Beam energy: 90keV

100

Ta-(polycrystal)
Ta-(single crystal)Cu-(polycrystal)Cu-(single crystal)

50

Intensity: 500nA
Diameter: 3mm

0
0

200

400

600

800

Time from the biginning of the bombardment1000( x 10 sec.)

References[1] N. Kawachi et al. UTTAC annual report 66(1997)62[2] N. Kawachi et al. UTTAC annual report 67(1998)95- 59 -

3.6

Formation of transition metal cluster silicides on gas phasereactions

A.Negishi, N.Kariya, K.Sugawara†, I.Arai and S.M.LeeThe study of the clusters composed of metal and silicon atoms has been carried out so far insome way using the laser ablation method [1]. Unfortunately the clusters including more than
two metal atoms were rarely found in such a way. The results were explained owing to the factthat the binding energy between two Si atoms is higher than that between Si and metal atoms.
In our previous studies mainly concerned with the reactivities of cluster cations toward simple
molecules in gas-phase, we proposed a method to make stabilized clusters in advance react tosilane molecules. The present experiment intends an investigation of the formation processes ofclusters including more than two metal atoms and their stabilities using a spectrometry with ahigh mass-resolving power.
The experimental apparatus mainly consists of an external laser ablation/supersonic jet cluster ion source and an Fourier transform ion cyclotron resonance(FT-ICR) mass spectrometer[2]. Cluster cations were produced by irradiation of Nd:YAG laser(532nm,15mJ/pulse) toward
a rotating niobium target. Only the cluster caions of roughly predetermine mass could pass anacceleration/deceleration tube. They were introduced into an FT-ICR chamber in a magnetic
ﬁeld of 3T, and ﬁnally trapped there by an electrostatic ﬁeld of 10V in an FT-ICR cell. The
FT-ICR chamber is in a vacuum of about 1.0 × 10−9 Torr. The trapped ions were thermalized
by collisions with argon atoms introduced through a pulsed valve. Later on, the ions began tocollide and react with 28 SiH4 molecules. After a certain time duration, reaction products wereobserved. We have measured mass spectra under changing the time duration(t = 0 − 30 sec) andthe reaction gas pressure of SiH4 gas(p = 1.0 × 10−8 − 2.0 × 10−6 Torr).
Fig.1. shows the obtained mass spectra for Nb+n (n = 1 − 12) on several conditions. The reaction was frequently occurred and produced the hybrid clusters Nbn Sim Hl . Because the observedhydrogen atom number l was only even, the dehydrogenation seems to proceed by releasing an
H2 molecule at a time. There was no detached ion including a fragment of niobium cluster.
+Nb+n + SiH4 −→ Nbn SiH2 + H2

(n = 1, 2)

(1)

+
Nb+
n + SiH4 −→ Nbn Si + 2H2(n = 3 − 9)(2)

While, the dehydrogenation takes place continuously through either (1) or (2) process, it canbe apparently recognized that the process eventually reaches at saturation. One explanation forthis saturation may be that the process can not proceed any more once the niobium clusters havebeen covered with one monolayer of Si atoms. This is because the binding energy between Si and
Nb is higher than that between Si atoms. Assuming that the number of attached Si atoms at thesaturation depends on the surﬁce area of the metal cluster, i.e., a seed, and estimated how many
Si atoms can be attached to the surface of niobium cluster cation. As Fig.2. indicates that thedependence of the number of attached Si atoms at the saturation depends on the cluster size inagreement with the above mentioned geometric model.

References[1] S.M.Beck, J.Chem.Phys., 90, 6306(1989).
[2] A.B.Vakhtin and K.Sugawara, Chem.Phys.Lett., 299, 553(1999).
†

Nanotechnology Reseach Institute, National Institute of Advanced Industrial Science and Technology,Tsukuba
305-8565,Japan- 60 -

Nb 9+

Abundance (Scaled)

548.4
438.7

5
4

678

3

329.0
219.4

1

109.7

Silicon atom
number , m

9Reaction time
0.5 sec

10

2

11
12

0.0
900.0

1000.01100.0Abundance (Scaled)

666.0

8

532.8
399.6
266.4

4

133.2

5

9

1200.0101300.01400.01500.0

m/z

1 sec

11
12

7

6

13

0.0
900.0

1000.01100.01200.01300.01400.01500.0m/z

12Abundance (Scaled)

1760.8Magic number

2 sec

1408.6

11
13
10
1415
9
8
16

1056.5
704.3
352.2
0.0
900.0

1000.01100.01200.01300.01400.01500.0m/z

Fig. 1. Mass spectra for Nbn Sim Hl ; observed after the time durations 0.5sec, 1sec, and 2sec,
respectively.

Silicon atom number , m

30
25
20
15
Experimental data
Geometric model

10
5
0

0

1

2

3

4

5

6

7

8

9

Cluster size , n

Fig. 2. Number of attached Si atoms; experiment (painted sqaures) and model calculations(painted circles).

- 61 -

3.7

Measurement of large-sized Cu cluster ions by using a quadrupole
deflector and a TOF mass spectrometer

H. Sasaki, S. G. Lee, I. Arai and S. M. Lee

During recent years we have developed a metal cluster ion source, some ion optics and a TOF mass
spectrometer for investigation of a multi-charged cluster fission[1]. For that purpose, we need to produce
large-sized clusters and to observe to the change of their instability in the vicinity of phase transition. As
for a Na cluster, the phase transition occurs near the size of 1400. Other metals has similar critical sizes[2].
As a preliminary experiment, we have tried to generate and measure a large-sized metal cluster.
Main features of the experiment are shown in Fig. 1. The metal cluster was generated by a magnetron
type sputtering source with an aggregation cell cooled down by liquid nitrogen. The pressure inside theaggregation cell was 1torr filled with a mixture of He and Ar gases while the flow was controlled over therange from 40sccm to 60sccm. The length of aggregation region was also controlled from several cm to
20cm. Both the flow and the aggregation length influenced the distribution of cluster size seriously. We
used copper for a target material. The cluster ions were continuously accelerated to -1kV floating tube
which contains two electrostatic lenses to transport them efficiently. The DC cluster ion beam was chopped
and accelerated toward a ground potential level by an acceleration grid consisting of four electrodes. The
electrodes were separated in a length of 2mm from each other and their applied voltages were -1kV, -10V,+655V and 0V, respectively. The ion beam was decelerated between the first electrode and the second one.
After passing through the second electrode, the ions were stopped at the point of 0.03mm ahead from thesecond electrode. Then, we changed the voltage of the second electrode to +1kV rapidly so that the ionswere accelerated toward the third electrode as a pulsed bunch. The kinetic energy of the ions became 1keV
when they arrived at the fourth electrode. The ions were bent at an angle of 90 degree by the quadrupole
deflector in order to separate uninteresting neutral clusters from the bunch. At the exit of the quadrupole
deflector, cluster ions enter a 4m long field-free region where their drifts separated themselves in a time
domain. The cluster ions were detected by an electron conversion type detector biased up to -8.5kV fora post acceleration effective to detect heavier cluster ions. We measured TOF spectra by using the pulse
switch trigger as a start signal and the detector output as a stop signal, both of which were lead to the
inputs of a multi-stop time to digital converter(P7886E, FAST ComTec). The range of TOF should beover a few ms in the case of larger clusters. Therefore, we adjusted a frequency of the trigger to 30Hz.
Fig. 2 shows a typical mass spectrum of copper cluster ions. The peaks of 40 Ar+ , 63 Cu+ , 65 Cu+ ,+Ar2 and Ar+
3 were used for mass calibration. The large-sized Cu clusters with the size n ranging from2,400 to 24,000, i.e., the mass ranging from 150,000amu to 1,500,000amu were observed. The spectrum
had a dip structure around 600,000amu. We can not explain why the observed spectrum splits into twobump structures. The mass distribution could be controlled to a certain extent by adjusting the aggregation
length or pressure in the aggregation cell. For example, the mass distribution shifted to the low mass side
resulting in the spectrum over the region from 100,000amu to 600,000amu when we decreased the flowof Ar up to 40sccm. In conclusion, by using this cluster source and ion optics, various-sized clusters havebecome available for the use of multicharged cluster fission experiment.

References[1] H. Sasaki, S. G. Lee, I. Arai and S. M. Lee, UTTAC annual report 4.9 (1999)[2] T. P. Martin, T. Bergmann, H. Göhlich and T. Lange, Z. Phys. D19, 25(1991).

- 62 -

Quadrupole
Deflector

Field Free Region

TMP
500l/s
MCP with Electron
Conversion Cup
TMP

Acceleration
Grid

TMP
500l/s500l/s-1kV floating tube
& lenses

Lq.N2 Coolant

TMP
500l/sMagnetron type
Cluster Source

Fig. 1: Schematics of experiment.

cluster size (atoms/cluster)
5000

100

10000

15000

20000

10000

Yield(a.u)

80

8000
6000
4000

60

63

65
+
Cu
+

Cu
+

Ar2

+

Ar

Ar3

2000
0
0

50

100

+

150

40
20
0

0.5

1

mass, (amu)

1.5
[×
×10 ]
6

Fig. 2: Mass distribution of (Cu)+n . The length of aggregation region was 13cm while the amount of theflow of He/Ar gases was 60sccm/60sccm.

- 63 -

3.8

The effect of biased electrode on operation of ECR ion source using
liquid He free superconducting solenoid coils

M. Imanaka, T. Kurita, M. Tsukada, T. Nakagawa1 and S.M. Lee
To produce an intense highly charged ion beam from an electron cyclotron resonance ion source(ECRIS), various methods have been developed. One of those methods is to install a negatively biased
electrode on microwave injection side in the source[1]. A beam intensity enhancement with this method isoften explained due to an increase of the electron density caused by a reflection of electrons fromnegatively biased electrode[2-4]. However, little is known about its detailed mechanism.
We have constructed a liquid He free superconducting ECRIS (SHIVA) and successfully extracted
various intense beams of heavy ions[5]. For example, the beam intensity of 1.4eµA and 5.7eµA have beenachieved for Xe35+ and Xe32+, respectively. In SHIVA, the biased electrode method was used and its
effectiveness was recognized. We have studied the mechanism of the bean intensity enhancement
systematically by observing how the electrode effects on the beam intensity.
For a detailed setup of SHIVA, see the figures in ref. [5]. Fig. 1 shows a schematic diagram of theplasma chamber and the biased electrode in SHIVA. The biased electrode is movable along the beam axis.
In the present experiment, we have measured the intensity of highly charged Xe ion beam and the currentof biased electrode as a function of both the applied negative bias voltage and the position of electrode.
Main experimental parameters are listed in Table 1. In addition, we have observed a time structure of thebeam intensity with use of digital storage oscilloscope.
Figs. 2 and 3 show the intensity of measured Xe20+ beam and the current of biased electrode according
to the changes of bias voltage and electrode position, respectively. In Fig. 2, we can see that both the beam
intensity and the current of biased electrode become higher with an increase of bias voltage. It seems
reasonable to suppose that this fact supports the above mentioned mechanism providing reflected electrons
from the electrode. The current of biased electrode is thought to be a current of the electrons reflected by
the electrode into ECR plasma. On the other hand, Fig. 3 shows that the beam intensity changes largely
depending on the position of biased electrode, although the current of biased electrode has little
dependence. It may be said that the change of bias voltage and the change of the electrode position can act
on different dynamics of ECR plasma from each other.
Some of the measurements of time structure for the beam intensity are shown in Fig. 4. In thesemeasurements, we observed that the beam intensity oscillated strongly when the negative bias voltage wasapplied to the electrode. Fig. 5 shows the measured Xe24+ beam intensity and the oscillation frequency as afunction of the biased electrode position. Furthermore, we have plotted a correlation chart between the
Xe24+ beam intensity and the oscillation frequency in Fig. 6. Fig. 6 indicates an apparent positive
correlation between them, i.e., that the frequency becomes higher with an increase of the negative bias
voltage. It follows that the biased electrode causes a certain instability in the ECR plasma, resulting in the1

The Institute of Physics and Chemical Research (RIKEN)- 64 -

enhancement of beam intensity.

Table 1. Main experimental parameters
extraction voltage
15kV
14.5 GHz RF power
565W
axial
injection side
1.85T
magnetic
central side
0.40T
field
extraction side
1.18T
vacuum of injection side
1.6*10-6Torr
vacuum of extraction side
3.3*10-7Torr

Fig. 1. A plasma chamber and a biased
electrode in the sources SHIVA.

Fig. 2. A Xe20+ ion beam intensity and a current

Fig. 3. A Xe20+ ion beam intensity and a currentof biased electrode as a function of electrodeof biased electrode as a function of electrodeposition.

position.

Fig. 4. A time structure of Xe24+ beam intensity- 65 -

Fig. 5. A Xe24+ ion beam intensity and an
oscillation frequency as a function of biased
position.

Fig. 6. A correlation between Xe24+ beam intensity
and oscillation frequency

References[1] G. Melin et al., Proceedings of the 10th Int. Workshop ECR Ion Sources, Oak Ridge Nat. Lab.,
Knoxville, 1991, 1.
[2] R. Geller, Electron Cyclotron Resonance Ion Sources and ECR Plasmas, IOP, Bistol (1996).
[3] T. Nakagawa et al., Proceedings of the 14th Int. Workshop ECR Ion Sources, CERN, Switzerland(1999)1.
[4] S. Biri et al., Proceedings of the 14th Int. Workshop ECR Ion Sources, CERN, Switzerland (1999)81.
[5] T. Kurita et al. Rev. Sci. Instrum., 71(2000)909.

- 66 -

3.9

Production of highly charged xenon ions from liquidhelium-free superconducting electron cyclotron resonanceion source (SHIVA)

T.Kurita, M.Imanaka, M.Tsukada, T.Nakagawa 1 , I.Arai and S.M.Lee
In recent years, we are constructing a facility for experiments to study dynamic behaviors
of metal clusters like ﬁssion, multi-fragmentation. For studying it, we need to produce a highly
charged metal cluster through multiple ionization. For that purpose, one of the most eﬀective
methods is a soft peripheral collisions of highly charged heavy ions with a metal cluster [1]. In
this method, it is crucial to use an intense beam of highly charged heavy ions such as Xe32+ .
In the last 15 years, the performance of Electron Cyclotron Resonance Ion Sources (ECRISs)
have been so intensively improved that they are able to produce intense beam of heavy ions [2].
To produce the intense beam of highly charged heavy ions for the experiment in which the ionscollide with metal clusters, we have constructed a superconducting ECRIS called by the nameof SHIVA. The source has remarkably unique characteristic that it dose not need liquid helium
to obtain the superconductivity of solenoid coils. In this paper, we report the performance ofSHIVA for the production of highly charged xenon ions.
Figure 1 shows the cross sectional view ofCurrent LeadSHIVA. A detail design of the source is de4.2K/50K Refrigerator
scribed in Ref. [3]. Main characteristics of
20K/80K Refrigerator
SHIVA are listed in Table .1. The superconducting solenoid coils are cooled by small
Giﬀord-McMahon type refrigerators below 5
K. It allows to keep the superconductivity ofThermal Shield
Cooling Conductorsolenoid coils without supplying liquid helium.
Vacuum Chamber
These solenoid coils are used to supply the mir- 3.0 Superconducting
Solenoid Coil
3T
Iron Yoke
Thermal Insulating Support
ror magnetic ﬁeld to conﬁne the plasma in the 2.5
RF2Taxial direction. The maximum strength of mir- 2.0
4.2K
Hexapole Magnet
ror magnetic ﬁeld is 3 T at the microwave in- 1.5
jection side (Binj ) and 2 T at the beam extrac- 1.0
0.5T
tion side(Bext). The center coil works in a re- 0.5
versed current mode, which allows to adjust the 0.0
-800
-600
-400
-200
0
200
600
800
400
minimum strength of the mirror magnetic ﬁeld
Gas Inletaround the center. The hexapole magnet which
480
555
consists of 24 segment of permanent magnets
is used to conﬁne the plasma in the radial direction. The inner and outer diameters of theFig. 1. A schematic of SHIVA
hexapole magnet are 80 and 174 mm, respectively. The maximum magnetic ﬁeld strength at the inner surface of the plasma chamber is 1
T. The inner diameter of the plasma chamber is 72 mm. To protect the hexapole magnet fromdemagnetization due to a possible increase of operating temperature, the wall of plasma chamber
has a double-layered structure to allow a ﬂow of cooling water. The injected microwave frequency
is 14.5 GHz. Its maximum power is 2 kW.
For production of xenon ions, we used an enriched 136 Xe gas with enrichment of 85 %. As thegas mixing method is very eﬀective eﬀective to increase the beam intensity for all elements witha mass heavier than a carbon [2], we used natural oxygen gas as the mixing gas. In addition, anegatively biased electrode was placed in the plasma chamber for increasing the beam intensity[2].
The electrode is circular disc of 25 mm in diameter made of stainless steel. The inner surface
1

The Institute of Physical and Chemical Research (RIKEN)- 67 -

Table 1. Main characteristics of SHIVA

maximum axial ﬁeld strength(superconducting coils)
hexapole ﬁeld strength at surface of plasma chamber(permanent magnets)
inner diameter of plasma chamber
length of plasma chambermicrowave frequency
maximum microwave power

3 T (Binj ) - 2 T (Bext )1T
72.1 mm
375 mm14.5 GHz
2 kW

of plasma chamber is covered by aluminium of 1 mm thickness. The Al2 O3 formed on the wall
increased the secondary electrons produced under the impact of plasma particles, which may inturn increase the electron density and the source performance [4]. The extracted xenon ions bya potential diﬀerence of 15 kV were analyzed by a 90 degree bending magnet, and their charged
state distribution was measured with a Faraday cup at the focusing point of the bending magnet.
Figure 2 shows a typical charge state distribution of xenon ions when the ion source is tuned
for producing Xe32+ ions. The main parameters for producing these ions are also listed in Fig. 2.
Under this condition, we have achieved obtained 9.6 µA of Xe30+ , 5.7 µA of Xe32+ and 0.9 µAof Xe36+ with a microwave power of 760 W. A typical conﬁguration of the mirror ﬁeld is shownin Fig. 3.
Xe28+
30+

Current [eµA]

10

Xe

8

Xe32+

Xe 32+ Tuned
gas
extraction voltage
RF powerbias voltage
electrode position
vacuum of injection sidevacuum of extraction side

:
:
:
:
:
:
:

136

Xe (85 % enrich) / O2
15 kV
760 W
225 V
5 mm
9.5×10-8 Torr
1.9×10-7 Torr

6

O2+, Xe17+
4

1.84T
1.5
Magnetic Field [T]

12

1.24T

1.0

0.5

35+

Xe

0.39T

2

0.0
0

20

40

60

0
3

4

5

6

7

8

80
100
Position [cm]

120

140

Injection Side

9160

Extraction Sidem/q

Fig. 3. A typical magnetic ﬁeld conﬁguration

Fig. 2. A charge stage distribution forxenon ions, optimized for Xe32+

100

Beam Intensity [eµΑ]

Figure 4 shows a comparison the beam intensities of highly charged xenon ions among
SHIVA and other high performance ECRISs
using 14.5 GHz microwaves. SERSE is asuperconducting ECRIS of the Laboratorio
Nazionale Sud (L.N.S.), Catania [5]. The ion
source has a large plasma chamber and superconducting coils which are refrigerated with liquid helium and applied to solenoid coils and ahexapole magnet. Caprice is a compact ECRIS
using room-temperature coils, which was developed in CEA, Grenoble [6]. It is clearly seen in
Fig. 4 that the beam intensity becomes rel-

- 68 -

10

Bmax : 1.2T (Caprice)1

Bmax : 2T (SERSE)
Bmax : 1.85T (SHIVA)

0.1
15

20

25

30

35

40

Charge State of Xe Ions

Fig. 4. Comparison of intensities of xenon
ions among various ECRISs using
14.5 GHz microwaves

atively enhanced so much in comparison withthose of other sources in the region of higher
charge state. It means that SHIVA is suitablefor producing higher charge state compared to SERSE and Caprice.
The dimensions and other parameters of SHIVA, SERSE and Caprice are listed in Table 2.
From Table 2, we consider that following characteristics of SHIVA contributes the high performance of SHIVA.
• A long plasma chamber; A long plasma chamber contribute to a longer ion conﬁnement
time [7].
• High magnetic ﬁeld; A high magnetic ﬁeld contribute to a longer ion conﬁnement time [7]and a higher plasma density [2].
• An aluminium cylinder in the plasma chamber; The aluminium cylinder may helps toincrease the plasma density with secondary electrons emitted from its surface [4]. Also it isexperimentally conﬁrmed that aluminium oxide on inner wall of a plasma chamber reduce
plasma potential [8] and ion conﬁnement time is extended.

Table 2. Comparison of dimensions and other parameters among various 14.5 GHz ECRISs

Bmax of axial magnetic ﬁeld
radial magnetic ﬁeld
length of plasma chamber
aluminium cylinder or chamber
typical injected RF power

SHIVA
1.85 T
1T
375 mmyes∼800 W

SERSE
2T
1.1 T
420 mmno∼1200 W

Caprice
1.2 T
1.08 T
160 mmyes∼1200 WTo summarize, SHIVA shows a remarkable performance to produce highly charged xenon ions.
It has been found that SHIVA is the most suitable for producing a highly charged state comparedto other currently working 14.5 GHz ECRISs.

References[1] F. Chandezon, C. Guet, B. A. Huber, D. Jalabert, M. Maurel, E. Monnandand, C. Ristori,
J. C. Rocco, Phys. Rev. Lett. 74 (19) (1995) 3784.
[2] R. Geller, Electron Cyclotron Resonance Ion Sources and ECR Plasmas, IOP, Bristol, 1996.
[3] T. Kurita, T. Nakagawa, T. kawaguchi, S.-M. Lee, Rev. Sci. Intrum. 71 (2) (2000) 909.
[4] T. Nakagawa, Y.Miyazawa, M. Hemmi, T. Chiba, N. Inabe, M. Kase, T. Kageyama, O. Kamigaito, A. Goto, Y.Yano, Jpn. J. Appl. Phys. 35 (7) (1996) 4077.
[5] S. Gammino, G. Ciavola, L. Celona, M. Castro, F. Chines, S. Marletta, Rev. Sci. Intrum.
70 (9) (1999) 3577.
[6] D. Hitz, F. Bourg, M. Delaunay, P. Ludwig, G. Melin, M. Pontonnier, T. K. NGuyen, Rev.
Sci. Intrum. 67 (3) (1996) 883.
[7] T. Rognlien, T. Cutler, Nucl. Fusion 20 (8) (1980) 1003.
[8] Z. Q. Xie, C. M. Lyneis, Rev. Sci. Intrum. 65 (9) (1994) 2947.

- 69 -

3.10

Physical process of cluster formation in sputtering of various
metals with 6keV Xe atoms

I. Arai, J. Hirose, H. Sasaki, K. Teranishi and S.-M. Lee
The sputtering, i.e., the particle emission from the surface of bulk material bombarded by anenergetic atomic particle, has long been studied. However, most of the published works on the
sputtering have focused mainly on the measurement of the total sputtering yield while the studyof the phenomenon such as cluster emission remains as one of the least understood ﬁeld. Even
the basic mechanism of the cluster formation has not been established yet [1].
In the earlier stage of study, the cluster formation in the sputtering was perceived as theemission of a whole particle from the bulk surface of bombarded material[2][3]. Subsequently, thestatistical agglomeration processes of individual sputtered atoms was perceived as an alternative[4][5]. Later,ﬁrst principles calculations of cluster emission based on molecular dynamics(MD)simulation have been carried out[6]. It was found that the MD simulation in combination with a
new many-body potentials among target atoms successfully described the formation of Ag clusters
in sputtering of metallic surface. Very recently, a more simpliﬁed model inspired by the resultsof MD simulation was proposed[7]. By considering a metal as a system of harmonic oscillators,
the model successfully described the emission of large clusters in sputtering of metals Al, Nb, Ag
and Ta with atomic and polyatomic ion bombardments. It was concluded that the larger clusters
are emitted as whole agglomerates during the early stages of collision cascade.
It should be noted that a completely diﬀerent approach to this issue emerged from a related ﬁeld of research for supported clusters in parallel with the progress of such ﬁrst principles
calculations. Recent studies of the cluster formation on bulk surface with a molecular beam
epitaxy[8][9][10] have successfully applied the scaling Ansatz[11][12] [13] for the analysis and understanding of a fundamental cluster formation mechanism. They have proved the usefulness of ascaling concept and strongly suggest that the application of scaling Ansatz should be also usefulfor the study of cluster formation in the sputtering. Indeed, they have shown an alternative way
to describe the cluster formation, i.e., to describe it in terms of critical phenomena[14]. It isgreatly expected that we can get a new insight on the cluster formation in the sputtering fromthis new point of view.
As for the experimental observation of cluster formation in the sputtering, a power law natureof cluster abundance spectra has long been discussed in many literatures(see, for instance, [4][15][16][6]). In the reference [15], it has been remarked that the abundance spectra of Cu, Ag and Aucluster ions produced by the bombardment of Cu, Ag, and Au targets with 10keV Xe ions [17][18]can be ﬁtted very well with a power law N (s) ∼ s−2.7 up to the highest mass s of 40. At the sametime, it has been also suggested that this observation may be a signature of critical phenomena
related to the universality classes belonging to fragmentation phenomena which concern a wide
diversity of objects in nature.
Very recently, the abundance spectra of fragments produced by high energy nuclear collision
has been reproduced remarkably well within a framework of a parameter free percolation model
treating a nucleus as a simple ﬂuid and it has been suggested that the percolation could be anuniversal mechanism to explain the fragmentation of simple ﬂuid[19]. It has been also remarked
that experiments with atomic clusters would help to conﬁrm the hypothesis. In this connection,
the cluster formation in the sputtering could be considered as a fragmentation of the solid surface
bombarded with energetic atoms and a new systematic measurement and a new analysis along
the above direction should be done urgently.
In our previous experiment, we measured the abundance spectra for 3d transition metalclusters produced by the bombardment of 6keV Xe atoms [20]. We successfully applied the scaling
Ansatz for the cluster abundance spectra in the sputtering of 3-d transition metals for the ﬁrst timeand observed a striking similarity among the scaled spectra. To understand further, we carried- 70 -

out a model calculation based on a 2-dimensional bond percolation model with the concentrationof broken bonds p as an only parameter. The model worked quite well. Furthermore, a strong
anti-correlation between the concentration of broken bonds and the thermal conductivity at 976K
for each bombarded material was found[21].
In the present experiment, we have examined cluster abundance spectra for various metals
with diverse melting temperatures ranging from 500K to 4000K. Our previous experiment has
strongly suggested that the physical process of cluster formation in sputtering is closely related
to the series of thermal transport phenomena, e.g., the injection of heat by 6keV Xe atom
bombardment, the diﬀusion of heat around the metal surface, the associated structural changes inthe surface, and the resulting cluster emission. We have considered that the melting temperature
is a key issue making a serious eﬀect on such structural changes.
We have observed cluster abundance spectra for various metals by bombarding a target material with a 6keV Xe atom coming from a FAB source(see Figure 1). The cluster cations accelerated by an extraction potential of 10 kV were guided to a high resolution mass analyzer(JEOLm
JM S − HX 110) with a mass resolution of ∆m∼ 5000 and a mass range up to 5000 amu.
10000000000
Mg Data
Mo Data
Nb Data
Pb Data
Ta Data
W Data1000000000

Abundance N(s)100000000
10000000
1000000
100000
10000
1000
100

0

5

10

15

20

Cluster Size s

Figure 1: Cluster abundance spectra for various materials
We have applied a scaling Ansatz[13] for those spectra. The abundance spectrum N (s) forthe cluster size s should be given by a scaling form
N (s) = N0 s−τ f (s/S),(1)

where N0 is a normalization factor, τ is a critical exponent, f (s/S) is a cutoﬀ function and S isa mean cluster size, i.e., only one characteristic size, deﬁned by
S =

∞ 2
s N (s)s=1.
∞
s=1 sN (s)(2)

In the equation (1), the term s−τ describes a scale-independent part while the term f (s/S)
describes a scale-dependent one, i.e., a ﬁnite-size eﬀect.
We have made scaling plots for the measured cluster abundance spectra N (s) with a value of 2,i.e., a superuniversal value, for τ (see Figure 2). Surprisingly, it is found that all the spectra overlap
each other by adjusting their normalization factors. As a result, we have found a remarkable
regularity among the measured cluster abundance spectra.
To understand further, we have carried out a calculation based on a percolation theory[22][23].
To keep the situation as simple as possible, it is assumed that the metal surface consists of the- 71 -

18

0.33xMo
Nb
2xPb

16

3xTa

ln[s*s*N(s)]

W
5xMg

14

12

10

8

6
-1.5

-1

-0.5

0

0.5

1

1.5

2

2.5

ln[s/S]

Figure 2: A scaling plot of abundance spectra for various metals
atoms arranged in 2-dimension and connected with each other by a bond and that a cluster
is formed when all of its circumferential bonds are broken Here, it should be noted that theconcentration of broken bonds p is an only parameter to ﬁt the experimental data.
Each of the measured cluster abundance spectra has been reproduced very well with a suitablevalue of p(see Figure 3). We assume that the bonds are broken by a thermal excitation so thatthe value of p for each target material should depend on both the eﬀective bond energy and local
temperature of bombarded surface at the stage of cluster formation, which are considered closely
related to the melting temperature Tm [24] and thermal conductivity k[25] of a bulk material,
respectively. We have examined possible correlations between the concentration of broken bonds
p and each of the Tm and k for all target materials. As shown in Figure 4, it is found that the pis strongly correlated with the Tm . As for k, any meaningful correlation has not been observed.
10000000000

Abundance N(s)Mg Data
Mo Data
Nb Data
Pb Data
Ta Data
W Datap=0.77p=0.88p=0.90p=0.75p=0.93p=0.891000000000
100000000
10000000
1000000
100000
10000
1000
100

2

4

6

8

10

12

14

16

18

20

Cluster Size s

Figure 3: Size distributions of clusters for various metals; calculations based on bond breaking
model(lines) and experimental data(symbols)
To understand such a strong correlation, we have considered a substantially new model ofthe physical process underlying the cluster formation in sputtering. Our idea consists of the- 72 -

Fraction of Empty Bond p

1
Ta

0.9

Nb

Ti
Fe
Co

0.8
Mg
Pb

W

Mo

V
Cr

Ni

0.7

0.6

0.5
500

Cu

1000

1500

2000

2500

3000

3500

4000 K

Melting Point Tm

Figure 4: A strong correlation between the melting temperature Tm and the concentration of
broken bonds p for various metals;previous experimental results are included
followings;(1)thermal diﬀusion on the surface, (2)the associated formation of thermally isolated
small area, the equilibrium temperature being kept much higher than the melting temperature ataround the bombardment position, and (3)cluster formation within the thermally isolated area
as a result of bond breaking.
At ﬁrst, a δ-function like temperature distribution is formed around the bombardment posi2
tion. Secondly, the thermal energy is transported following the diﬀusion equation ∂T∂t = κ∇ T .
The diﬀusion coeﬃcient is given by the formula κ = Ckρ ρ where Cρ and ρ are the speciﬁc heatand density of target metal, respectively. At a certain time in a course of the thermal diﬀusion,a mechanical stress take place around the peripheral circular area where the temperature goes
down to under the melting temperature Tm for the ﬁrst time shortly after going up above the Tm .
As a result, the inner part bounded by the area becomes thermally isolated due to a structural
discontinuity such as a ﬂaw or a crack caused by the stress. Finally, the isolated part is kept in
the equilibrium temperature Teq , which is greater than the Tm , and clusters are formed by bondbreaking.
At the time t, the temperature distribution φ(x, y, t) on the surface is given by the equation

φ(x, y, t) =φ0x2 + y 2
exp −
2πκt
2κt

,

(3)

where φ0 is a normalization constant which depends on the initial condition. The bombardment
point is chosen as an origin of the coordinate system. If we assume φ(x, y, t) = Tm , thecorresponding radius r = x2 + y 2 is reduced as
r 2 = 2κt ln

φ0.
2πκTm t(4)Then, the position of discontinuity riso is evaluated as a maximum of r as follows;
φ0
πeTm

(5)

φ0
.
2πκeTm(6)

riso =
while the corresponding time tiso is given bytiso =- 73 -

The inner part surrounded by the discontinuity becomes thermally isolated resulting in the equilibrium temperature


riso
1
φ(x, y, tiso)dxdy
2πriso 0= Tm (e − 1).

Teq =

(7)

According to a statistical theory, the concentration of broken bonds p is a function of Teq givenby the equation
D∗)
4kB TeqD∗= P0 exp(−),
4skB (e − 1)Tm

p = P0 exp(−(8)

where P0 , D∗ , and kB are a normalization factor, an eﬀective dissociation energy of bond, and a
Boltzmann constant, respectively. In Figure 5, it is found that the equation (8) is hold well forvarious metals while M g and P b seem not to follow the equation. Here, we assume that P0 andD∗ are constant for simplicity. In the case of M g and P b, the dissociation energy D ∗ is expected
to be considerably small compared to the case of other metals because of their small cohesiveenergies[24]. The smaller D∗ gives the larger p.
1

P0 e -D*/kB (e-1)Tm

Ta
Nb

0.9
Ti
Fe
Co

0.8

ln p

Mg

W

Mo

V
Cr

Pb
Ni

0.7

Cu

0.6

0.5
500

1000

1500

2000

2500

3000

3500

4000 K

Melting Point Tm

Figure 5: A correlation between the melting temperature Tm and the concentration of brokenbonds p for various metals; a model calculation (solid line) and experimental results(symbols)
In summary, we have measured the abundance spectra of clusters for various metals producedby the bombardment of 6keV Xe atoms. Applying a scaling Ansatz for those spectra, we havefound that all the spectra coincide with each other. Guided by the observation of this remarkable
regularity, a bond breaking model, i.e., a variant of bond percolation model assuming a mechanical break-up of the sputtered surface, has been examined. The model has successfully reproduced
all the spectra resulting in an eﬀective value for the concentration of broken bonds p of eachmaterial. The p’s are strongly correlated with the melting temperatures of bulk materials. To
understand such strong correlation, we have proposed a substantially new model of the physical process underlying the cluster formation in sputtering. Our idea consists of the followings;(1)thermal diﬀusion on the surface, (2)the associated formation of thermally isolated small area,
the equilibrium temperature being kept much higher than the melting temperature at around thebombardment position, and (3)cluster formation within the thermally isolated area as a result- 74 -

of bond breaking. The model has reproduced the eﬀective value for the concentration of brokenbonds p of each material very well.

References[1] W.O. Hofer, in Sputtering by Particle Bombardment III eds.:R. Behrisch and K. Wittmaack,
Topics in Appl. Phys., 64, Springer-Verlag, Berlin, 1991(chapter2)74.
[2] G. Staudenmaier, Radiat. Eﬀ., 13(1972)87.
[3] W.O. Hofer, Nucl. Instrum. Methods, 170(1980)275.
[4] F. Honda et al., J. Chem. Phys., 69(1978)4931.
[5] R.A. Haring et al., Nucl. Instrum. Methods Phys. Res., B28(1987)205.
[6] A. Wucher et al., J. Chem. Phys., 105(1996)5999.
[7] S.F. Belykh et al., Nucl. Instrum. Methods Phys. Res., B155(1993)409.
[8] M. Zinke-Allmang et al., Phys. Rev. Lett., 68(1992)2358.
[9] J.G. Amar et al., Phys. Rev., B50(1994)8781.
[10] G.S. Bales et al., Phys. Rev., B50(1994)6057.
[11] M.E. Fisher, Rep. Prog. Phys., 30(1967)616.
[12] K. Binder, Ann. Phys. (N.Y.), 98(1976)390.
[13] D. Stauﬀer, Phys. Rep., 54(1976)1.
[14] H. E. Stanley, Rev. Mod. Phys., 71(1999)S358.
[15] X.Campi, in The Chemical Physics of Atomic and Molecular Clusters,Proceedings of International School of Physics  EnricoF ermi  (1988:Varenna, Italy), edited by G. Scoles,
North-Holland, Amsterdam, Course CVII(1990)231.
[16] M. Wahl et al., Nucl. Instrum. Methods Phys. Res., B94(1994)36.
[17] I. Katakuse et al., Int. J. Mass Spectrom. Ion Processes, 67(1985)229.
[18] I. Katakuse et al., Int. J. Mass Spectrom. Ion Processes, 74(1986)33.
[19] X.Campi et al., Eur. Phys. J., 11(2000)233.
[20] I. Arai et al., Proceedings of 4th CCST Symposium, Sendai, Japan, May 11-12(2000)57.; I.
Arai, Desorption2000 Int. Conf., Saint Malo, France, Sept. 3-7, 2000; I. Arai et al., Transactions of MRS-J 26(2001) to be published.
[21] For a high-purity metal, the k is almost constant above the room temperature[24]. Actually,
we need the k at a few thousands K, which is probably similar to the k at 976K, i.e., theavailable highest temperature in the cited tables. As for Co, we adopted the k at 373K becauseof the lack of value at 976K.
[22] M.B. Isichenko, Rev. Mod. Phys., 64(1992)961.
[23] D. Stauﬀer , Introduction to Percolation Theory, Taylor and Francis, London, 1994.

- 75 -

[24] C. Kittel, Introduction to Solid State Physics, Sixth Edition, John Wiley and Sons, NewYork(1986).
[25] CRC Handbook of Chemistry and Physics, ed. D.R. Lide, 80th Edition, CRC Press, Boca Raton(1999); American Institute of Physics Handbook, eds.: B.H. Billings et al., Third Edition,
McGraw-Hill Book Company, New York(1972).

- 76 -

3.11

Metal cluster growth in a gas aggregation cell combined with a magnetron sputter

C. K. Chung, H. Sasaki, S. G. Lee, I. Arai and S. M. Lee

In order to elucidate the processes of metal cluster formation and growth, we have constructed a metalcluster source controlled with a magnetron, and a reflective TOF mass spectrometer[1]. A series of mass
spectra of the growth of metal clusters from a monomer vapor to several thousands of atoms per cluster
for Ti were observed for the first time. As expected, the Ti monomers grew into clusters upon increasing
the growth length of the cluster source; the size distribution unexpectedly split into two dominant bandsof peaks. One band extended over the range from 1 to 15 atoms par cluster and the other was in the region
above 15 atoms per cluster. Moreover, we observed that the position of the boundary between the twobands of peaks was independent of the temperature of the aggregation cell and the vapor pressure of the
Ti atoms.
To assess the dependence of the position of the boundary point on the compositions of the clusters, weobserved cluster growth for Al and several transition metals: Zn, Zr, Ta and W. All the materials displayed
two separated bands of peaks at the initial stages of growth in the same way as Ti did. However, thepositions of the boundary between the two bands of peaks are different. Surprisingly, our experimental
results deviated enormously from the expectations of classical nucleation theory[2]. Furthermore, at theinitial stages of the cluster growth, abrupt decreases of monomer concentration were observed. Thissuggests that cluster formation via monomer absorption can be restricted within the growth of clusters ofseveral atoms.
Up to now, it has been thought that the cluster formation from a vapor phase involves a stepwise
process. The monomer absorption is believed to be dominant among small-sized clusters. And, when
the density of clusters becomes high enough for coalescence, it is believed that a coagulation gradually
become a dominant process[3]. However, no complete theory exists to explain such a stepwise process.
Unfortunately, no experiments have quantitatively elucidated the details of the stepwise process in cluster
growth, up to now. However, we have observed experimentally for the first time the transition fromsuccessive monomer absorption to cluster coalescence in the cluster growth.
Our experimental results suggest a new model of cluster growth in a gas aggregation source controlled with a magnetron as shown in Fig. 1. Our model, which is a time-limited monomer absorption
model based on coalescence, describes the experimental results very well, including the dependence ofthe position of the boundary between the two bands of peaks observed in the size distribution on the composition of the clusters[Fig.2]. Furthermore, with the interpretation of growth process provided by ourmodel, we found an interesting tendency observed at the initial stages. As shown in Fig. 3, the cluster growth of lighter materials by monomer absorption is stronger than that of heavier ones because thecollision frequency between atoms of lighter materials is higher than that of heavier ones. In addition, amaterial, which has a high cohesive energy, shows a stronger monomer absorption through an increaseof the monomer absorption length(W). In general, a heavy material has a high cohesive energy. As themass number increases, the collision frequency decreases slowly; however, the cohesive energy abruptly
increases. Therefore, monomer absorption process should be maintained for a longer time for the cluster
growth of heavy materials than for that of light materials. As a result the position of boundary in the mass
spectra reflects the competition between the monomer absorption and the coalescence for each material.
This is the first attempt to describe metal cluster growth from a monomer to a cluster on the basis ofexperimental observations.
There remains the problem of how the heat of condensation is evacuated from a cluster. With a highenough vapor pressure for the carrier gas and cooling with liquid nitrogen, it is thought that all of thelatent heat can be extracted by collision with the carrier gas. However, this hasn’t been quantified yet.

- 77 -

On this point, it must be realized that the heat produced by the coagulation of an i-sized cluster with a jsized one is enormously less than the heat produced by the condensation of monomers on a j-sized cluster.
The clusters can transfer the in internal heat into translational energy [4]. Therefore, after the cluster has
attained a certain size, the coagulation can continue under a relatively little production of internal heat.
However, it is not known whether the internal heat produced by monomer absorption in a gas aggregation
cell is negligible.
In addition, there are problems concerned with the clustering of the carrier gas and the attachment of
the carrier gas to the metal clusters. The Ar attachment seems to promote the speed of cluster growth andlower the internal energy of the metal clusters. This effect is dependent on the composition of the clusters.
However, little data on effects of gas attachment to metal clusters appears to exist.
Finally, the details of the cluster growth process are very complicated. Various factors, e.g., the temperature, pressure and velocity of the gas and metal vapor, the geometry of the aggregation cell, thediameter of the diaphragm and the available pumping speed, should influence the cluster growth. The
fact that they are all interdependent makes an accurate quantitative analysis extremely difficult. We must
acquire a better understanding of such interdependency in order to fully explain the cluster growth.

References[1] C. K. Chung, I. Arai, and S. M. Lee, UTTAC Annual Report 1999, Tandem Accelerator Center,
University of Tsukuba.
[2] C. K. Chung, I. Arai, and S. M. Lee, Transactions of the Materials Research of Japan, 25[4] 955-958(2000).
[3] C. K. Chung, Doctoral thesis, 2001, University of Tsukuba.
[4] J. M. Soler and N. Garcia, Phys. Rev. A, 27, 3300 (1983)- 78 -

Fig. 1: Model of cluster growth in ourcluster source. L is a total growth length and W a length of monomer
absorption region.

Fig. 2: Size distributions of Ti clusters calculated from the rate equations of our model[4].

Fig. 3: Comparison of model calculations with experiment. The boundary points of the size distributions
are plotted with respect to mass number and cohesive energy for severalmaterials.

- 79 -

3.12

The science of 3d transition-metal oxide system

M. Onoda, N. Nishiguchi, R. Arai, I. Amemiya, K. Kogure, J. Hasegawa, A. Oyadomari, D.
Kasuga, K. Kanbe, H. Imai, K. Sekine, A. Tokunaga and T. Banno
The structural and electronic properties of 3d transition-metal oxides and bronzes have been
explored by means of x-ray four-circle diﬀraction and through measurements of magnetic resonance (NMR and EPR), magnetization, and electronic transport, in order to extract peculiar
properties in the correlated electron and electron-phonon-coupling systems, low-dimensional spin
conﬁgurations, and novel materials.
Varian continuous-wave and Bruker pulse NMR spectrometers have been used at the Tandem
Accelerator Center. In spite of rather old equipments, these spectrometers have been working
by a careful maintanance. However, in order to obtain more detailed results, it is necessary torenovate the equipments.
In 2000-2001, the following investigations have been performed:• Correlated-electron and electron-phonon-coupling systems– Spin-gap state in Mx V2 O5 (M = Ag and Tl)– Mixed valence state in Cu7 V6 O19– Metal-insulator transition in V1−x Crx O2– Anomalous diamagnetism in RVO3+δ/2 (R = La and Y)• Quantum spin-ﬂuctuation system– Superexchange interaction in MV3 O7 (M = Cd1−x Cax and Ca1−xSrx )– Geometrical frustration in CdV2 O4• Lithium secondary battery system– Li inserition eﬀect in M1+xV3 O8 (M = Li, Ag and Na)– High capacity in Ag2 V4−x Mox O11

Geometrically frustrated system; CdV2 O4
The geometrically frustrated system has been investigated for a long time. Here, a state where
all pairs of the nearest-neighbour spins are aligned to the opposite direction is not allowed andthe spin correlation is suppressed, so that the transition temperature to possible ordered states
is reduced signiﬁcantly. This system sometimes undergoes a structural transition to the lower
symmetry, since it brings the proﬁts of the orbital and magnetic energies with resolving thedegeneration. The triangular S = 1 system LiVO2 is one of such materials, where spin-singlet
trimers are formed [1].
The spinel-type Mott insulator MV2 O4 with nonmagnetic M2+ and magnetic V3+ also exhibits
the frustration eﬀect [2, 3]. Here, M has a tetrahedral coordination (A-site) and V has anoctahedral one (B-site). The network of V ions is expressed as the linkage of a regular tetrahedron
block that has the V ion at each apex. On the other hand, LiV2 O4 with average valence of V3.5+
is a metal and it has recently been considered as being one of the heavy-fermion system at low
temperatures [4]. Moreover, the mechanism of metal-insulator transition in the Lix Mg1−x V2 O4
system has been investigated in detail [5]. In this report, the structural and magnetic properties of
CdV2 O4 are described brieﬂy, revealed through measurements of x-ray diﬀraction, magnetization
and NMR.
The lattice constant of CdV2 O4 is determined to be a = 8.688(1) Å, which is consistent withthe previous report [6]. A part of the x-ray diﬀraction patterns at 82 and 296 K is shown in Figs.

- 80 -

1(b) and 1(c). The (440) peak at 296 K splits to two peaks at 82 K with the intensity ratio of
about 2:1, whereas the (111) peak at 296 K does not change at 82 K. This result indicates thatthe crystal system at 82 K may be tetragonal with the axial ratio c/a = 0.990. The temperaturedependence of the lattice constant is shown in Fig. 1(a). In the heated process, the ﬁrst-order
cubic-tetragonal transition appears at Tc1 = 97 K.

8.72

a c

(a) CdV2O4

(422)
(440)
(220)

(422)

56
2θ (deg)

60

296K
82K

(b)
16

80

(440)

8.60

(333)
(511)

8.64

(111)

Intensity (arb unit)a, c (C)

8.68

(c)
17
2θ (deg)

120

18

52

160

200

T (K)
Fig. 1: (a) The temperature dependence of the lattice constants for CdV2 O4 estimated from thepeaks of (422), (440) and (220) reﬂections; (b) and (c) a part of the x-ray diﬀraction patterns at
82 and 296 K.
The temperature dependence of the magnetic susceptibility χ for CdV2 O4 is shown in Fig.
2(a) and the low-temperature part is indicated in Fig. 2(b). A jump of the susceptibility appears
at 97 K, corresponding to the cubic-tetragonal transition temperature Tc1 . At temperatures
below Tc1 , the susceptibility has a maximum at 73 K, and another anomaly with an abruptchange of the temperature-derivative occurs at Tc2 = 35 K. No diﬀerence was observed between
the susceptibilities for the zero-ﬁeld-cooled and the ﬁeld-cooled process at 1 T.
The magnetic susceptibility of the B-sublattice with S = 1 is expressed in terms of hightemperature series expansion (HTSE) of up to the 8th-order as follows,C(1 − 4/t + 12.33333/t 2 − 32/t3 + 76.80556/t 4 − 187.4963/t 5Jt+ 478.71677/t 6 − 1221.6871/t 7 + 2978.22367/t 8) + χ0 ,

χ =

(1)

where C is the Curie constant, J is the exchange coupling constant [7], t is the reduced temperature t = T /J, and χ0 is the constant susceptibility. The full curve for CdV2 O4 in Fig. 2(a)is drawn on the basis of the parameters; C = 0.98(2) emu K (molV)−1, J = 44(1) K and χ0= 1.8(2) × 10−5 emu (molV)−1. C agrees well with the value calculated from the spin with S= 1 and g = 2. Comparing the present result with those of MgV2 O4 and ZnV2 O4 [2, 3, 5], we
conclude that the V-V direct exchange coupling is the most eﬀective in the MV2 O4 system.
A single resonance line of the 51 V-nuclei in CdV2 O4 was observed, although the intensity wasvery weak. A plot of the Knight shift K against χ is shown with an implicit parameter T in Fig.

- 81 -

χ (10 emu (molV) )24

CdV2O4MgV2O4
ZnV2O4

–4

–1

–4

–1

χ (10 emu (molV) )32

34 (b)

17

32

16

30

15

28

14

0

40

80
120
T (K)

600

800

16

8

(a) MV2O4

0

200

400

160

1000

T (K)
Fig. 2: (a) The temperature dependence of the magnetic susceptibility χ of CdV2 O4 ; and (b) the
behaviour at low temperatures. The full curve in (a) indicates the result on the basis of HTSE
analysis of up to the 8th-order. The results for MgV2 O4 and ZnV2 O4 are also presented.
d3. The linear relation is seen and the hyperﬁne coupling constant Hhf
is estimated to be –7.1 T−13+µB , which is close to the value for V of LiVO2 [1] and is smaller than those of V2 O3 [8]. The
51
V-NMR has not been observed at temperatures below Tc1 . It is not clear whether the signal
disappears or becomes weaker.
In summary, the structural and magnetic properties of CdV2 O4 have been revealed for theﬁrst time. The structural transition at 97 K, and the magnetic anomalies at 97 and 36 K exist
there. The HTSE analysis of up to the 8th-order indicates that the V-V direct exchange couplingis the most eﬀective in MV2 O4 .

References[1] M. Onoda M and T. Inabe: J. Phys. Soc. Jpn. 62 (1993) 2216.
[2] H. Mamiya and M. Onoda: Solid State Commun. 95 (1995) 217.
[3] H. Mamiya, M. Onoda, T. Furubayashi, J. Tang and I. Nakatani: J. Appl. Phys. 81 (1997)
5289.
[4] S. Kondo, D. C. Johnston, C. A. Swenson, F. Borsa, A. V. Mahajan, L. L. Miller, T. Gu,
A. I. Goldman, M. B. Maple, D. A. Gajewski, E. J. Freeman, N. R. Dilley, R. P. Dickey, J.
Merrin, K. Kojima, G. M. Luke, Y. J. Uemura, O. Chmaissem and J. D. Jorgensen: Phys.
Rev. Lett. 78 (1997) 3729.
[5] M. Onoda, H. Imai, Y. Amako and H. Nagasawa: Phys. Rev. B 56 (1997) 3760.
[6] B. L. Chamberland and J. F. Wu: J. Electrochem. Soc. (1988) 921.

- 82 -

–0.4

K (%)

–0.8

–1.2

–1.6

–2.0

CdV2O4
20

24
28
–4
–1
χ (10 emu (molV) )32

Fig. 3: The K − χ plot of CdV2 O4 at temperatures above 100 K.
[7] The Heisenberg Hamiltonian is deﬁned as H =at site i.

<i,j> JS i ·S j , S i being the spin operator[8] A. L. Kerlin, H. Nagasawa and D. Jerome: Solid State Commun. 13 (1973) 1125.

- 83 -

3.13

Mössbauer study of some granular magnetic materials

F. A. Khan*, K. Ono, M. Nakazumi and E. Kita
Granular magnetic materials have been investigated as a candidate of magneto transport materials
such as giant magneto-resistance (GMR) and tunneling magneto-resistance (TMR). They are composedof ferromagnetic fine grains and nonmagnetic matrix of both metals and insulators, and are rather novel
magnetic materials compared with traditional materials such as bulk soft magnetic materials or magnetic
recording media. These must be categorized into the nano structured material. In this report we
examined some ferromagnetic granular systems that include Fe atoms as a magnetic element.
Mössbauer study and magnetization measurements of Fe-Cu granular system(metallic granular material)
and Fe-CoO(insulating granular system) will be described. The strong magnetic coupling between
ferromagnetic Fe atoms and antiferromagnetic CoO can be expected and its magnetic property andelectrical conduction are also of interest.
Samples of granular materials were prepared with sputtering.

For a metallic system such as

Fe-Cu, it is possible to use dc sputtering that makes production rates high when small Fe tablets areplaced on the Cu base plates.

In order to increase the quantity of Fe in the fabricated samples, we use

an Fe metal mask with high coverage area. In this case, the sputtering system was necessary to be
switched to the rf-sputtering because of a difficulty in keeping plasma discharge on the ferromagnetic
mask by using dc sputtering.

The dc power supply had to be replaced by a rf-power source with an

impedance box connected with it. The composite target was a circular disc of pure Cu of 5-mm
thickness. The Cu disc was covered with the Fe mask which was of same diameter as the Cu disc. For
the deposition of Fe-Cu nano-granular films, both thin glass sheets and Kapton films were used as
substrates. After ultrasonic cleaning by ethanol, the substrates were dried up by air jet and set on to thetarget.

Several films of Fe-Cu were made on Kapton films and also on the thin glass substrates withdifferent sputtering time and rf-power. Table 1 shows the thickness of three different samples of Fe-Cu
thin films produced at three different base pressures and with rf-power constant at 200 watt.
Table 1. Fe-Cu rf-sputtered nano-granular thin films
SampleAr pressure

Thickness(Å)(Torr)

Sputtering time

Fe composition(min.)(at %)

5.4x10

-2

2450

5

32

#2

7.5x10

-2

1680

5

35

#3

1.0x10-1

1550

5

38

#1

The sputtering time was 5 minutes with 5 minutes of pre-sputtering in each case. Composition analysis
was carried out with an ICP (Inductively Coupled Plasma photoemission) spectroscopy for Fe-Cu thin*

JSPS short term visiting fellow from Bangladesh University of Engineering and Technology- 84 -

film.

The compositions were ranged between 32 and 35 at % of Fe.

The data suggest highrepeatability in controlling their composition by using this technique.
Figure 1 shows Mössbauer spectra of Fe-Cu granular thin films in a as-prepared state (a), annealed
at 300 °C for l h. (b) and annealed at 400 °C for l h. (c). No significant changes in the Mössbauer
spectrum were observed in the annealed sample at 300 °C.

The spectrum is composed of aparamagnetic doublet.

However remarkablechange in the spectrum was observed after
annealing at 400 °C for 1 hr. A well defined
Relative Transmission

1.000

ferromagnetic sextet was observed in the
Mössbauer

0.995

spectrum

(see

Fig.1

(c)),

indicating the presence of α-iron in the sample.

0.990

Magnetization measurements were done with a
0.985

commercial SQUID magnetometer. For the(a)measurements of magnetization the samples

0.980
FeCu#2 As-preared
0.975
-12

-8

-4

were cut into 5 x 5 mm2 pieces. Field cooled
0

4

8

12

Velocity (mm/s)

and zero-field cooled measurements were doneon the sample. The magnetization curve showsa typical Langevin function indicating that the

1.000

Relative Transmission

magnetization process is mainly dominated by
0.995

large scale particles.

shows an gradual increase with the decrease of

0.990

temperature and has a broadened peak around

0.985

20

(b)
0.980

0.975
-12

The magnetization

K,suggestingthepresence

super-paramagnetic blocking.

FeCu#2 300ºC 1h annealed

of

the

This would

however have to be confirmed by relaxation
-8

-4

0

4

8

12

Velocity (mm/s)

measurements.

No relaxation measurements

have been done on the samples.
For the fabrication of Fe-CoO granular

Relative Transmission

1.000

thin films, Fe-CoO composite target was used.
0.995

As CoO is very fragile it is convenient to use
the iron mask instead of iron screw tablets.

0.990

Similar deposition conditions to Fe-Cu cases

0.985

0.980

0.975
-12

were used to fabricate the samples. Figure 2

(c)

shows

FeCu#2 400 ºC 1 h annealedtheMössbauer

spectrumofanas-deposited Fe-CoO sample. The sputtering
-8

-4

0

4

8

12

Velocity (mm/s)

time for this sample was 30 minutes. Figure 3
shows the Mössbauer spectrum of the same

Fig. 1.
Mossbauer spectra of an FeCu granular thinfilm(sample#2), (a) as-grown, (b) annealed at 300 °C for 1 hand (c) annealed at 400°C for 1 h.

- 85 -

sample after annealing at 400 °C for 1 h.
From the result for the as-prepared sample, Featoms in the film were not in a ferromagnetic state, but in a paramagnetic state. This means that Fe
atoms form small grains in a superparamagnetic state or form compounds with lower magnetic transition
temperature than room temperature. The field cooled magnetization measurements were carried out at
an applied magnetic field of 3 T at 5K. The curve shows a shifted hysteresis with different values ofremanent magnetization and cohesive fields. Such asymmetry may have originated in the exchange
anisotropy of the sample due to the magnetic coupling between ferromagnetic Fe and antiferromagnetic
CoO layers.
1.001
1.000

Relative Transmission

Relative Transmission

1.000
0.999
0.998
0.997
0.996

0.998

0.996

0.994

Fe-CoO granular film
as-deposited

0.995
0.994
-12

-8

-4

0

4

8

12

Fe-CoO granular film
annealed at 400 ºC
0.992
-12

-8

-4

0

4

8

12

Velocity (mm/s)

Velocity (mm/s)

Fig.3. Mössbauer spectrum of an Fe-CoO. granular thinfilm annealed at 400 °C for 1 h.

Fig.2. Mössbauer spectrum of an as-prepared
Fe-CoO. granular thin film.

Further magnetization measurements and low temperature Mössbauer studies are necessary in order tomake the magnetic property more clear.

- 86 -

4.1

Quantitative trace element analyses of single fluid inclusions inhydrothermal quartz by PIXE

M. Kurosawa, S. Shimano, T. Kato, K. Shima and S. Ishii
Fluid inclusions in hydrothermal veins are important as the most convincing informationof fluid activities and vein-type ore formation. In particular, elemental compositions of fluidinclusions provide a direct evidence for chemistry of hydrothermal fluids and ore-forming
processes. Thus considerable efforts have been invested in the development of techniques forthe precise quantitative elemental analyses [e.g.; 1-6]. Fluid inclusions are extremely small,typically less than 30 µm, and a single mineral grain contains several generations of fluidinclusions with distinctly different compositions. As a consequence, high sensitive microbeam
analyses of individual fluid inclusions in the grain are essential. Owing to its high spatial
resolution, non-destructive character and high sensitivity for almost element (Z>22),
proton-induced X-ray emission (PIXE) is a reliable technique for quantitative element analysis ofsingle fluid inclusions [7-9]. In this study, we have reported determinations of trace elements in
fluid inclusion from hydrothermal quartz and examined the relationship with vein-type skarn
Fe-Cu deposits.
The quartz sample was collected from Kawahage quartz veins at Kawakami village,
Nagano Prefecture in the central Japan. The quartz veins intrude Mesozoic sandstone, mudstone
and limestone strata and has a genetically relationship to the Kinpusen biotite-granite body at the
distance, 2 km, from the veins. Fe-Cu mines of skarn type are also present near the veins and are
regarded as the same hydrothermal generation with the veins. The quartz veins are simple quartz
veins and consisted partly of a skarn body formed by reactions with the calcareous country rock.
The main quartz part had a large amount of rock crystals and a small amount of chlorite andnative gold. The skarn part contained calcite, quartz, hedenbergite, vesvianite, andradite,scapolite, pyrite, pyrrhotite, chalcopyrite. Measured fluid inclusions in the specimen were
included in a milky quartz crystal, 5 cm in length, from the main quartz part. The quartz crystal
sample was cut parallel to the C axis, 500 µm in thick, and was mounted on a slide glass andpolished; then were coated with a carbon film to avoid the charging-up. The measured fluidinclusions were selected from a trail of secondary inclusions with negative crystal shapes, 30-170µm in size, and contained saline water, vapor bubbles, and NaCl crystal (Fig.1). The estimated
NaCl equivalent concentration was of ca. 30% and the inclusion depth was 12 to 20 µm.
These samples were measured by the PIXE facility at the Tandem Accelerator Center, theUniversity of Tsukuba [10]. A 0.1 to 0.4 nA beam of 4-MeV proton was focused to a 50 x 100µm spot on the sample using slits and magnetic lenses. The incidence beam angle was normal
to the sample surface, and the X-ray measurement take-off angle was 45˚. Analytical points
were chosen based on optical viewing using a CCD camera mounted on the microscope. The
characteristic X-rays excited by the incident beam were collected by the Si(Li) X-ray-energy- 87 -

Fig. 1
Photomicrograph of fluidinclusions in quartz crystal
from Kawahage.
The
inclusions contained saline
water, vapor bubbles, andcubic NaCl crystal (whitearrow). Scale bar is 200µm.

detector with a nominal resolution of 145 eV at 5.9 keV, and the spectra were recorded by amulti-channel analyzer. A graphite plate, 1.3-mm thick, was located between the specimens andthe detector in order to attenuate the intense X-rays from the light major elements. The total
charge was determined by integrating the target currents, and all samples were analyzed to theintegrated charges of 0.5 to 5.0 µC.
The measured X-ray intensity for each element was converted to the elemental
concentration by the developed quantification method using sensitivity curve [11]. The method
included three calculations necessary for X-ray analyses of inclusions buried in matrix: 1) energy
loss of incident protons in the matrix; 2) intensities of characteristic X-rays emitted from theinclusion; and 3) absorption of the X-rays by the matrix. Sensitivities of the detector for eachelement was determined by measurements of multi-element reference glass material NIST SRM
1412 (Table 1). The sensitivity was a maximum at Fe, so that the present analytical condition
was suitable to determinations of transition metal elements. By using the method, trace elements
in fluid inclusions at levels of a few to several thousands µg g-1 can be determined with theprecision of ±11 % [11]. Detection limits for the measurements depended mainly on elemental
species and the integrated charge. The lowest run detection limits with the integrated charges of
5.0 µC were of 1.8 x 10-13 g for Ga and 5.7 x 10-11 g for Ba. For measurements of fluidinclusion with 30 µm diameter, estimated detection limits for Ga, the most easily detectable, wasof a few µg g-1.
Observed spectra of the fluid inclusions consisted mainly of the K-X ray peaks from Ca,
Mn, Fe, Ni, Cu, Zn, Ga, Br, Rb, Sr, and the L-X ray peaks from Pb (Fig. 2). These peaks were
present in all the inclusions in the same trail. L-X ray peaks from Ba, La, and Ce were also
visible in large inclusions, 150 µm length (Fig. 2). In addition, small Cu peak was detected fromthe quartz matrix, so that fluid inclusion contents were quantified by subtracting contributions of
Cu in the matrix to the inclusion contents. Determined concentration of the- 88 -

Fig. 2
X-ray spectrum oflarge single fluidinclusion recorded
using 0.5 µC of 4
MeV protons with
1.3 mm graphite.

large inclusion was shown in Table 1. Ba, La, and Ce, were unable to be determined due to thesmall intensities. The determined values of Mn, Fe, and Cu, were 2-3 orders of magnitude
higher than those of cold spring water near the veins [12], indicating higher transition metal
contents in the hydrothermal fluid related with ore formations. By considering a fractionation of
Cu-Pb-Zn in hydrothermal fluid, features of the lower Cu, higher-Zn and -Pb have demonstrated
a generation of the fluid at shallower depth conditions: it consisted with geological occurrences
and mineral assemblages of the veins and the adjacent skarn mine. The presence of La and Ce
has shown a strong contribution of residual components generated by crystal fractionations of
granite to the fluid. In addition, the high concentration of Ca agreed with an occurrence of theskarn part in the veins, showing Ca supply in thefluid from the calcareous country rock.
Table 1. PIXE analyses of single fluidinclusion in quartz crystal.
The present results have proven that thefluid in the inclusions contained transition metal
X-raysensitivity
concenintensity
tration-1
elements and Ca at several 100-1000 µg g
(cts)
(cts (µC cm-2)-1 g-1) (µg g-1)
level and detectable light rare earth elements.
Ca 1018707147919
6781
These chemistries have indicated a fluidMn 4553
13473129052
365
generation by the mixture of granitic andFe 33103
15326418531
2189
Cu 1275
13385639168
71
country rock components and by the Cu-Pb-Zn
Zn 12466
11381919498
891
fractionation at a relatively shallower depthBr
1834
3548738939
400
Rb
612
2139246646
214
conditions (~1 kb). In the future, it would be
Sr
550
1671372584
246
required further elucidation of origin for these
Pb 1202
1870619833
491
transition metals, for example, crystal
fractionation of granite or scavenging them from- 89 -

sedimentary rock. As further works, analyses of fluid inclusions in the hydrothermal veins arein progress.
References[1] J. D. Frantz, H. K. Mao, Y.-G. Zhang, Y. Wu, A. C. Thompson, J. H.
Underwood, R. D. Giauque, K. W. Jones and M. L. Rivers, Chem. Geol., 69(1988), 235.
[2]

L. W. Diamond, D. D. Marshall, J. A. Jackman and G. B. Skippen, Geochim.

[3]

Cosmochim. Acta, 54 (1990), 545.
A. H. Rankin, M. H. Ramsey, B. Coles, F. Van Langevelde and C. R. Thomas,
Cosmochim. Acta, 56 (1992), 67.

[4]
[5]

T. J. Shepherd and S. R. Chenery, Cosmochim. Acta, 59 (1995), 3997.
P. Philippot, B. Menez, P. Chevallier, F. Gibert, F. Legrand and P. Populus,[6]Chem. Geol., 144 (1998), 121.
A. Audetat, D. Gunther, C. A. Heinrich, Science, 279 (1998), 2091.

[7]
[8]

C. A. Heinrich, C. G. Ryan, T. P. Mernagh and P. J. Eadington, Econ. Geol., 87 (1992) ,1566.
C. G. Ryan, C. A. Heinrich, and T. P. Mernagh, Nucl. Instrum. Meth. Phys. Res.

[9]

B77(1993), 463.
M. Kurosawa, S. Shimano, T. Kato, S. Sueno, K. Shima and S. Ishii, UTTAC-67 annual

report (1998), 112.
[10] M. Kurosawa, S. Sueno, K. Shima, H. Ohshima, S. Ishii, H. Kamiya, S.
Kimoto, H. Ohyi and K. Hayashi, Nucl. Instrum. Meth. Phys. Res. B142 (1998),
599.
[11] M. Kurosawa, S. Shimano, T. Nakajima, T. Kato, S. Sueno, K. Shima and S. Ishii,
UTTAC-68 annual report (1999), 94.
[12] K. Sugihara and T. Shimaguchi, Sci. Rep. Edu. Yamanashi Univ. 36 (1985), 23.

- 90 -

4.2

Permeability modification of rat intestine induced by inflammation
shown with PIXE measurement

K.Nakao1, Y. Suzuki1, Y. Saito1, I. Tamanoi2, K.Shima, S. Matsumoto3
1. Introduction
Intestinal tract, in particular small intestine, plays a part in control of digestion and absorption ofnutrient, while defending from poison, bacteria, virus and so on. Inflammatory bowel disease, Crohn's
disease and ulcerative colitis, are multi-factorial disorders whose etiology remains unknown. Although theexact pathogenesis is poorly understood, there is evidence that it involves interactions among the immune
system, genetic susceptibility, and the environment, most notably the bacterial flora. In patient with
Crohn's disease, the intestinal inflammation mainly occurs in small intestine. It is difficult to evaluate
technically the severeness of the disease in small intestine by endoscopic and radiographic examinations.
Activity of the disease is evaluated by clinical symptoms and sub-clinical features, for example, laboratory
data by blood test.

In patient with the inflammatory bowel disease, abnormal increase in intestinal

permeability has been responed as a characteristic symptom. It is afraid that substances which can't be
usually uptaken by the organ permeate through the mucosa. Current methods to measure intestinal
permeability need much time and also laborious work. More simple method to measure intestinal
permeability is desired.
We measured the intestinal permeability of mice by PIXE method, as one of the methods to assess theactivity of intestinal inflammation. PIXE method is able to measure a small amount of elements, which is
not easy to measure with usual one. We successively measured the amount of element in blood after oral
administration of heavy metals such as rubidium, manganese to mice[1-5]. The usefulness of PIXE
method is presented in measurement of intestinal permeability.
2. Materials and Methods
2.1. Animals and inflammation induction
We used Sprague-Dawley male rats (weight 200-250g) of 7 weeks old. These rats were obtainedcommercially from Japan SLC.

Inflammation was induced with injection of indomethacin with anamount of 10mg/kg/day, which was solved in 5% sodium hydrogen-carbonate (NaHCO3).
Physiological saline solution was injected to control groups.
2.2. Sample preparation
A mixture solution of 300mg of rubidium chloride (RbCl), 52.0 mg of manganese chloride(MnCl24H2O) and 18.7mg zinc chloride (ZnCL2), was administered orally into rats. The amount of RbCl,
MnCl2 and ZnCL2 administered was calculated from LD50 in rat according to Merk Index. After the

1 School of Medicine, Chiba University, 1-8-1, Inohana, Chuou-ku, Chiba-shi 260
2 National Institute of Radiological Sciences, 4-9-1, Anagawa, Inage-ku, Chiba-shi 263
3 Chiba Institute of Technology, 2-1-1, Shibazono, Narashino-shi 275-0023- 91 -

administration of RbCl, MnCl2 and ZnCL2, blood was drawn from vein into a heparinized glass capillary
tube at 0, 15, 30 min and l, 2 and 4 hrs. Drawn bloods in capillaries were centrifuged for 5 min to readhematocrit values. 10µ 1 of plasma after centrifugation were deposited on a polycarbonate membranefilter (Nuclepore, Costar Scientific Corporation,0.1µm pore size, 6 µm thick and 25 mm in diameter) witha micropipette for PIXE analysis, as described previously [1-5]. The specimens of plasma were dried
under a room temperature and used for PIXE analysis.
2. 3 PIXE measurements
Specimens of the plasma were bombarded with proton beams of 1.52 MeV from a Tandetron
accelerator installed at Accelerator Center of Tsukuba University for an accumulated charge of 2000 nC[6]. The beam spot was 2 mm in diameter and the current was kept at 5 - 8 nA. The measurement of
X-rays was carried out with a Si (Li) detector. The method of PIXE measurement and analysis were
described in previous papers [1-5].
3. Results
Changes of each element contents after Rb+Mn+Zn administration was obtained with the analysis
of element contents in rats by PIXE method.

Figure 1 shows changes in the relative amounts of Rb

after the administration. The variation curves according to the injection times of indomethacin indicate
gradual increases with no significant differences between the single injection group and none.

Incomparison with twice injection group, the content in the twice injection increased clearly after 30min to
2hrs with ratios higher than the control and the single.

Fig.1 Variation of Rb content in the plasma of rats injected with indomethacin after theadministration of the tracer elements of Rb, Mn and Zn.

- 92 -

Fig.2 Variation of Mn content after the administration.
Figure 2 shows changes in the relative amounts of Mn after the administration. The curves in the
figures behaved similarly to the correspond data in Fig.1.

The amount of Mn in the twice injectiongroup increases slightly with a low rate until 30 min after the administration; but begins to increase
remarkably at the point. The value in the plasma reaches maximum at 2hrs and then decreases.
Gradual increases in the control and the single injection group, however, continued until 4hrs.

Fig.3. Variation of Zn content after the administration.
On the contrary, the content of Zn behaved differently as shown in Fig.3.

All of the curves seemto be interpreted as gradual increase with maximum at 2hrs. There are no apparent difference among the- 93 -

three groups as observed in Fig.1 and 2. Thus, the tracer of zinc exhibited a different response toinflammation of intestine.
4. Discussion
The Rb content in control group is very little. There is little or no Rb in normal mouse blood.
After the administration of Rb, it is taken up by the intestinal mucosa into blood and its content increases.
The values of Rb and Mn reached maximum at 2hrs after the administration and decreases.

Rb isprobably transferred into plasma from intestinal mucosa at first and subsequently moves into blood cells.
Increases in the elements of Rb and Mn in the twice injected samples are clearly observed after
the oral administration. There is a little Mn in normal mouse blood. After the administration, Mn is taken
up by the intestinal mucosa into blood and the Mn content increases. This result suggested that intestinal
mucosal barrier was destroyed by inflammation and intestinal permeability upraised. They are probably
permeated into blood from intestinal mucosa. Recently the intestinal permeability has been noted as one of
the indicators to assess the activity of inflammatory bowel disease, for example Crohn's disease [7-9].

In

patients with Crohn's disease, the tight junctions appear to be abnormal with increased separation between
cells and abnormalities in the structural strands of the tight junctions [7]. Wyatt et al.[8] measured
intestinal permeability in patients with Crohn's disease using the lactulose-mannitol test. Each subject wasadministered with a solution containing mannitol and lactulose. Urine was collected for next 5 hrs.
Lactulose and mannitol in the urine were measured. The permeability index (lactulose/mannitol) was
significantly higher in patients than in controls. A significant correlation was found between the value ofthe permeability index and the probability of clinical relapse in Crohn's disease. These results show that
increases in intestinal permeability precede relapse in the disease and so are an indicator of sub-clinicaldisease. Howden et al.[9] measured intestinal permeability in patients with Crohn's disease using the51

Cr-EDTA test. Each subject was orally administered 51Cr-EDTA. Urine was collected over the next 24

hrs to measure 51Cr-EDTA in the urine. Small intestinal permeability to 51Cr-EDTA was raised in patientswith Crohn's disease affecting the small intestine, and the degree of permeability is correlated with somemeasures of disease activity. On the other hand, urinary excretion of 51Cr-EDTA was not elevated inpatients with Crohn's disease who were judged to be in clinical remission or in their apparently healthy
first-degree relatives.

Above-mentioned methods have been applied to measure intestinal permeability.

However, these methods have difficulty in practice, since they need much more time for measurement andalso laborious work. Radioisotopes, such as 51Cr-EDTA, are radio toxin. More easy and safe method tomeasure intestinal permeability is desired.
5. Summary
In this study, we found that the element contents of Rb and Mn increased to peak level at 2 hrs after
the administration.

These were conspicuously observed in the plasma of the rats with intestine inflamedby twice injection of indomethacin in contrast with the Zn contents. It is possible to assess intestinal
permeability to compare the element contents of Rb and/or Mn at a short time after the administration. Rb
and Mn are useful as one of the tracers to study of intestinal disease with measurement by PIXE method.

- 94 -

The merit of this method with Rb and Mn tracers lies in its high sensitivity. They are easily and clearly
detected in the samples with PIXE method after the administration, in contrast with negligibly lower levelsof these element in normal mouse blood. Thus, intestinal permeability can be measured more simply by
PIXE method than other methods. At present, we are trying to induce the experimental animal models of
inflammatory bowel disease [10] and to measure intestinal permeability by PIXE method.

Further

investigations are in progress.
References[1] K. Nakao, Y. Suzuki, R. Sato, Y. Saito, I. Tamanoi. S. Matsumoto. H. Joshima, H. Imazeki, Possible
application of PIXE method to intestinal permeability measurement. Int. J. PIXE, 7, 219-231(1997)[2] K.Hoshikawa, I.Tamanoi, A.Nakamura, M.Kachi, K.Ohashi. S.Matsumoto, Possible characterizationof mouse strain by plasma analysis with PIXE. Int. J. PIXE. 4, 97-106. (1994)[3]

I.Tamanoi, A.Nakamura, K.Hoshikawa. M.Kachi. B.Goto. H.Joshima, S.Matsumoto, Changes ofblood plasma element contents in X-ray irradiated mice by PIXE analysis. Int. J. PIXE. 5. 85-95.
(1995)[4]

I.Tamanoi. A.Nakamura, K.Hoshikawa, M.Kachi, K.Ohashi. B.Goto. H.Joshima, S.Matsumoto,
PIXE studies on potassium and calcium in mouse blood plasma after transplantation of EL4 tumor
cells, Int. J.PIXE, 5, 255-264, (1995)[5]

I.Tamanoi, S.Ishizuka, S.Matsumoto, H.Joshima, H.Imazeki, K.Nakao, R.Sato, Y.Suzuki, PIXE
studies on the gastro-intestinal syndrome induced by radiation. Proceedings of the 34th Seminar on
Science and Technology, Small Accelerators & Their Application, 203-221, (1997)[6]

S.Matsumoto, M.Seki, H.Shima, T.Ishihara, Proton irradiation effect on the conductivity and thesurface structure of polymer materials.

[7]

UTTC Annual Report 67, 118-121 (1999)

D.Hollander. Crohn's disease - a permeability disorder of the tight junction?. Gut, 29, 1621-1624.
(1988)[8] J.Wyatt, H.Vogelsang, W.Hubl, T.Waldhder, H.Lochs, Intestinal permeability and the prediction of
relapse in Crohn's disease, Lancet, 341, 1437-1439, (1993)[9]

C.W.Howden, I.Gillanders, A.J.Morris, A.Duncan, B.Danesh, R.1.Russell, Intestinal permeability inpatients with Crohn's disease and their first degree relatives, Am. J. Gastroenterology, 8, I 175-1176,(1994)[10] C.O.Elson. R.B.Sartor. G.S.Tennyson, R.H.Riddell, Experimental models of inflammatory bowel
disease, Gastroenterology, 109, 1344-1367, (1995)- 95 -

4.3

A proposed method of the determination of the number of hydrogenatoms in a standard target for hydrogen analysis

K. Furuno, H. Ohshima, K. Sasa, Y. Sasaki, K. Yamada, S. Yokose, M. Ishizuka
and T. Komatsubara
A standard hydrogen target used in the hydrogen analysis by means of resonant nuclear reaction(RNRA)
must fulfill several conditions. An important condition is that the number of hydrogen atoms per unit areain the target is known. In previous works, the number of hydrogen atoms was determined by weighing[1]or by normalizing the yield of a target to that obtained with such an organic material as Kapton[2]. In thisreport, we propose an alternative method. It is the simultaneous observation of the angular distribution ofγ rays and the α-γ angular correlation for the H(19 F,αγ) reaction at the bombarding energy of the 16.44
MeV resonance. Although this proposed method could be applied to the H(15 N,αγ) reaction, the following
discussions are referred to the H(19 F,αγ) reaction only. Elastic recoil protons can also be observed with theidentical target-detector arrangement simultaneously. This is also used to measure the hydrogen concentration as described below.
1. Resonant nuclear reaction and elastic scattering by protons
It is well known that the 1 H(19 F,α, γ)16 O reaction can be employed to detect hydrogen atoms in materials. Many resonances are observed in this reaction at energies of 19 F ions between 4 and 26 MeV(lab). In
this energy range, the resonance at E(19 F)lab = 16.44 MeV shows the largest cross section of 590 mb. This
resonance was investigated by Seed and French[3] and Peterson[4]. The experimental data are summarized
in ref[5]. As indicated in Fig. 1, the system consisting of a proton and 19 F forms a compound nucleus
20 Ne at an excitation energy of 13.676 MeV, when the laboratory energy of 19 F reaches 16.44 MeV whichcorresponds to Ecm = 0.828 MeV in the center of mass system.

Figure 1: An energy diagram of 1 H(19 F,αγ)16 O resonant reaction. The branching ratios of 0.71, 0.23, and 0.07 forthe α decay from the I π = 2− compound state to the 6.13, 6.92, and 7.1 MeV state in 16 O are average values of two
different data reported in ref[3] and [4].

From the spins and parities of the proton, 19 F and of the state of the compound nucleus 20 Ne, the orbital
angular momenta should be odd in the entrance channel. The dominant partial wave is p wave at low centerof-mass(c.m.) energies. The resonance width Γ is reported to be 4.5 keV in the laboratory system, if we
observe the resonance by the bombardment of protons on 19 F target.
The 2− compound state decays into the excited states in 16 O via α-particle emission. The transitions to- 96 -

the ground and the first excited 0+ state are forbidden from the parity rule. Dominant transitions are thoseto the 6.13 and 6.92 MeV state, while the transition to the 7.12 MeV state is weak.
The measurement of the number of hydrogen atoms can be accomplished by observing α-particles or γ
rays emitted from the 6.13, 6.92 and 7.12 MeV state in 16 O. It should be noted here that the α-particles and γ
rays are emitted in successive transitions. One nuclear reaction produces one α-particle and one γ ray. The
lifetime of the 6.13 MeV state is measured to be 24 ps, and the 6.92 and 7.12 MeV state are also shortlived
states. The emission of α-particles and γ rays can be substantially regarded as simultaneous emission incomparison with the resolving time of a conventional detection system.
In the 1 H(19 F,αγ)16 O reaction, the kinetic energy of α-particle is high enough at forward angles becauseof large c.m. velocity in the reaction kinematics. It is about 11 MeV(lab) at 0◦ at an incident 19 F energyof 16.5 MeV. The range of this α-particle is much longer than that of incident 19 F ions. Therefore, if weplace an appropriate absorber foil behind a thin target which includes hydrogen atoms, 19 F ions stop in theabsorber foil, whereas α-particles pass through the foil. We can observe the α-particles at forward angles.
Recoil protons produced in the elastic scattering of 19 F on H in the target are emitted with energies
around 3 MeV at forward angles near the beam direction. Since the energy loss of protons is low, recoil
protons pass through the target and absorber foil. It is not always obvious whether the 19 F+p scattering ispure Coulomb scattering or not, because the detection of protons in the forward angle corresponds to theextremely backward scattering of 19 F. It should be noted, however, that the Coulomb barrier is as high as
2.45 MeV in the c.m. system. It is about three times as high as the c.m. energy of 0.828 MeV at 16.44
MeV resonance. If we assume the pure Coulomb scattering for the 19 F+p system at 0.828 MeV, the yieldof recoil protons gives the number of hydrogens in the target according to ERDA method. The solid angleof the α-particle detector must carefully be calibrated in this case.
2. The principle of the proposed method
The method consists of the simultaneous observation of a singles α-particle spectrum, a singles γ-ray
spectrum and α-γ coincidence spectrum at the resonance energy for the incident 19 F ions. The α-particle
detector can be designed in such a way that recoil protons can be observed simultaneously.
If we observe α-particles at an angle of (θα, ϕα) and γ rays at an angle of (θγ , ϕγ ) with respect to theincident beam, the yield of α-particles obtained in the singles mode is given by
Ysingles (α; θα ) = I0 n x ·d σ(ER, θα )
dΩα

lab

dΩαεα .

(1)

If the target and the incident beam are not polarized, the cross section does not depend on the azimuthal angle
ϕα. In the above expression, I0 stands for the number of incident 19 F ions, n is the number of hydrogenatoms per unit volume, x denotes the thickness of the target, dσ(ER, θα)/dΩα is the differential crosssection of the reaction at the resonance energy ER , dΩα means the solid angle of the α-particle detector.
The symbol εα is the detection efficiency of the α-particle detector, but this can be put to unity in most of
the cases. The energy resolution of the α-particle detector must be high enough to resolve the transition to
the 6.13 MeV state from that to the 6.92 MeV state in 16 O.
The yield of γ rays is written as
Ysingles (γ; θγ ) = I0 n x · σ(ER )WS (θγ )

dΩγ
εγ ,
4π

(2)

where the cross section σ(ER) is the integration of the differential cross section in eq(1) over the whole solid
angle. This is the value of the Breit-Wigner formula at the resonance energy ER . The function WS (θγ ) is
the angular distribution of γ rays. The energy resolution of the γ-ray detector must be high enough to resolve
two transitions to the excited states in 16 O mentioned above.
Since the resonance is a p-wave single resonance in good approximation, the angular distribution of γrays is not isotropic. The general expression of the angular distribution is expanded in a series of Legendre
functions as follows;
WS (θγ ) =aL PL (cos θγ )(3)
L=0, even- 97 -

with the normalization of a0 = 1. The solid angle and the detection efficiency of the γ-ray detector are
expressed by dΩγ and εγ , respectively. In practice, these are not independent; the product in the form of(dΩγ /4π)εγ can be calibrated.
The α-γ coincidence yield is given by
Ycoin (α, γ; θα , θγ ) = I0 n x ·d σ(ER, θα )
dΩα

lab

dΩαεα W (θα , θγ , ϕγ )

dΩγ
εγ ,
4π

(4)

where W (θα , θγ , ϕγ ) denotes the α-γ angular correlation function. This correlation function is greatly
simplified if α-particles are observed in the beam direction(θα = 0◦ )[7]. In this case, the correlation function
does not depend on the azimuthal angle ϕγ , and is given by the following form similar to eq(3);W (θγ ) =

AL PL (cos θγ )(5)

L=0, evenwith the normalization of A0 = 1.
The calibration of the detection efficiency of the γ-ray detector is performed as follows. At first, wemeasure the yields of Ysingles (α; θα = 0◦ ), Ysingles (γ; θγ ), and Ycoin (α, γ; θα = 0◦ , θγ ) simultaneously atangles of θγ as many as possible. The energy of the incident beam should be chosen to be the resonanceenergy at 16.44 MeV. From eqs. (2) and (4), we obtain following ratios;R(θγ ) =YcoindΩγ= W (θα , θγ )εγYsingles (α)
4π{1 + A2 P2 (cos θγ ) + A4 P4 (cos θγ )}

dΩγ
εγ .
4π

(6)

In this last expression, the Legendre expansion is limited within L = 4 for simplicity. The detection
efficiency (dΩγ /4π)εγ can be derived from the zero-th order coefficient of the fit of experimental ratios R
to the series of Legendre functions. It should be noted that this efficiency is only for the energy of 6.13 MeV.
Since the factors of I0 , nx, Ωα and εα are canceled by the fact that yields are observed simultaneously with
an identical condition for beam irradiation and the target-detector arrangement. The yield of singles eventsis much more larger than coincidence events. Therefore, only the counting statistics of coincidence events
contributes to the uncertainty of the detection efficiency in the zero-th order approximation.
After the calibration of the detection efficiency, we obtain the number of hydrogen atoms per unit areain the form of nx by fitting the observed yields Ysingles (γ; θγ ) to the Legendre expansion (see eqs. (2) and(3)). Since the detection efficiency is measured for only 6.13 MeV γ rays, the measurement of the angular
distribution should be perfomed for only this γ rays. The cross section σ(ER ) in eq(2) must be the partial
cross section through the 6.13 MeV state in 16 O. This cross section is measured to be 440 ±13 mb by Becker
et al[8]. The determination of the value of nx by ERDA method is an independent experiment, so that itprovides a good check for the measurements.
3. Test experiment
An experiment was carried out to test the validity and feasibility of the proposed method describedabove. An α-γ coincidence events were accumulated with a silicon solid-state detector placed at 0◦ for αparticle detection and 5 Ge γ-ray detectors arranged in a ring geometry at 63.5◦ with respect to the beam. The
target used was a 2 µm thick titanium foil. Hydrogen adsorption was performed in hydrogen atmosphereat 400◦ C. In this experiment, however, the energy resolution of α-particle detector was inadequate. The
singles events of α-particles were estimated from a comparison of spectrum shape between the singles andcoincidence spectra.
The singles and coincidence counts of α-particles were obtained to be 8.5922 × 105 and 3.638 × 103
counts, respectively. The angular correlation was evaluated from the theoretical function assuming that theresonance is a single p-wave resonance associated with the I π = 2− state in 20 Ne. The theoretical value at
W (θγ = 63.5◦ ) is 0.8. With these values, we obtained the efficiency of the γ-ray detector to be 5.29 × 10−3.
We measured hydrogen concentration of hydrated silica glass last year[9]. In this measurement, an obsidian sample was used as a reference of the hydrogen concentration. The experimental arrangement was- 98 -

the same as the test experiment of the above α-γ coincidence experiment. The counts of 6.13 MeV γ ray
was 10 counts per 1 µC for the obsidian sample. If we use the detection efficiency of 5.29 × 10−3 obtained
above, the hydrogen concentration of the obsidian sample is calculated to be nx = 6.9 × 1014 [H/cm2 ]. Thisvalue can further be converted to the concentration of water. It is 0.13 wt % H2 O, which is comparable witha value of 0.11 wt % H2 O obtained from the calibration by FTIR method. Since the error in the calibrationof the detection efficiency is at least 10 % or more, the agreement would be reasonable. However, moreelaborate experiments are clearly necessary, and will be continued together with the development of a new
microbeam system for hydrogen analysis.
References[1] Hjörvarsson, J. Rydén, T. Ericson and E. Karsson, Nucl. Instr. Meth. in Phys. Res. B42(1989) 257.
[2] L. Westerberg, L.E. Svensson, E. Karsson, M.W. Richardson and K. Lundström, Nucl. Instr.
Meth. in Phys. Res. bf B9 (1985) 49.
[3] J. Seed and A.P. French, Phys. Rev. 88, No. 5 (1952) 1007.
[4] R.W. Peterson, W.A. Fowler and C.C. Lauritsen, Phys. Rev. 96 No. 5 (1954) 1250.
[5] F. Ajzenberg-Selove, Nucl. Phys. A475 No.1 (1987) 163.
[6] K. Spyrou, C. Chronidou, S. Harissopulos, S. Kossionidos and T. Paradellis,
Zeit. Phys. A357 (1997) 283.
[7] A.E. Litherland and A.J. Ferguson, Can. J. Phys. 39 (1961) 788.
[8] H.W. Becker, W.E. Kieser, C. Rolfs, H.P. Trautvetter and M. Wiesher,
Z. Physik, A305 (1982) 319.
[9] N. Yanagisawa, K. Fujimoto, H. Ohshima and K. Furuno,
Annual Report of the Tandem Accelerator Center 1999, UTTAC-68, 2000, 113.

- 99 -

4.4 Preparation of standard targets for hydrogen analysis
K. Furuno, H. Ohshima, K. Sasa, T. Katabuchi, Y. Sasaki, K. Yamada, M. Ishizuka, S. Yokose,
and T. Komatsubara
A standard target for hydrogen analysis by means of the resonant nuclear reaction H(14 N,α, γ)12C or
H(19 F,α, γ)16 O must fulfill the following conditions.
1. The number of hydrogen atoms per unit volume is known.
2. The hydrogen concentration is reasonably high.
3. The hydrogen concentration is stable during ion bombardment.
4. It is suitable for use in high vacuum.
5. The chemical composition and density are well defined.
6. The electrical conductivity is reasonably high for reliable beam current integration.
Several organic films like Mylar, polystyrene, polyethylene and Kapton are attractive in the above items 1,
2, 4, and 5. All of these organic foils are insulator, so that thin coating with carbon or gold is necessary
to avoid charge up or sparking on the target during ion bombardment. The most serious drawback of theseorganic foils, however, is that the yield of gamma rays decreases as a function of the dose of incident ions.
In other words, the concentration of hydrogen atoms is not stable under the beam irradiation.@
Several authors have reported the preparation of hydrogen bearing targets so far. Hjörvarsson et alprepared tantalum-hydride(TaH x) samples by placing a 10 × 10 × 0.5 mm Ta plate which was heated at
620 K for 24 hours in hydrogen atmosphere at a pressure of 900 mbar[1]. The average concentrations
expressed by the ratio of atoms H/Ta were 0.41 ∼ 0.51. It was found that the concentration was uniform
over the depth from 0.3 to 1.0 µm from the surface. The samples were shown to be stable during the beamirradiation and resistant to heat treatment at 420 K in vacuum for achievement of ultra high vacuum. The
number of hydrogen atoms was calibrated by weighing method.
Westerberg et al investigated the performance of pyrolytic carbon and amorphous silicon as a hydrogenbearing target[2]. Although the thickness of the hydrogen bearing region that they tested was as thin as
0.3 µm, the stability under the ion bombardment was excellent in both of pyrolytic carbon and amorphoussilicon.
Thin deuterated titanium targets were prepared by Fletcher for his experiments on the D(d, p) andD(d, n) reaction at very low energies[3]. A thin titanium layer was made on a thin carbon foil by electronbombardment vacuum evaporation. The hydrogen adsorption was performed be heating the foil up to 400◦ C in hydrogen atmosphere.

One of the important problems in a standard hydrogen target is the calibration of the number of hydrogenatoms in the target. Hjörvarsson et al employed the weighing method. Westerberg et al normalized the γray yield of pyrolytic carbon and amorphous silicon to that of organic films by extrapolating the yields
to zero dose of incident ions. An alternative method of calibration is the use of such nuclear processes- 100 -

as proton-proton elastic scattering, the simultaneous observation of α-particles produced by the H(19 F,α)reaction and recoil protons(ERDA) with a thin hydrogen bearing target, or the α-γ angular correlation in thereaction H(19 F, αγ)16 O∗ on resonance. A progress report of our preparation for a stable standard target will
be described below.
We tested the adsorption method at first. As shown in Fig. 1,2

a 2 µm thick titanium foil and a 5 µm thick gold foil were put

1

between an aluminum disk and a washer. The aluminum disk
22

7

7

was 2mm thick and 22 mm in diameter, while the washer was
1mm thick and 13 mm in diameter. Both of the aluminum disk
and the washer had a hole of 7 mm in diameter at their center.
Ti

A simple heater was fabricated using a 30 × 30 mm square of

Au

Figure 1: Target composition.

ceramic plate and an electric ribbon heater as shown in Fig. 2.
The ribbon heater was

made of a sheet of thin molybdenum(Mo). We wound a 0.1 mm thick,
5 mm wide and 150mm long Mo ribbon in a flat shape.
The target composition shown in
Fig. 1 was placed in a vacuum chamber which was evacuated with a turbo
molecular pump. The change in the

Figure 2: Heater.

0.2

Temperature [C]Pressure [Torr]

B

A
0.1

400
H

200

0
0

0

50
100
Time [min]1500Fig. 3. Pressure during the adsorption.

50
100
Time [min]150

Fig. 4. Temperature during the adsorption.

pressure in the vacuum chamber and the temperature of the target composition, which was measured witha thermo couple at the edge of the washer of the target composition, are displayed in Fig.3 and Fig. 4. The
degassing of the heater was carried out before the target composition was mounted on it. We increased thetemperature of the target composition up to 527◦ C(see the mark H in Fig. 4). Hydrogen gas was introduced- 101 -

into the chamber when the temperature was decreased won to 250◦ C(see the mark A in Fig. 3). The pressurechange indicated by the symbol B in Fig. 3 occurred when we adjusted a needle valve to recover the pressure
which was decreasing gradually. The titanium foil, however, was very fragile, and had got many wrinkles
after this treatment.
Another method of the preparation was the implantation of H− ions at an energy of 90 keV. The target
composition was exposed to the H− ion beam from our polarized ion source operated in the unpolarized
mode. An aperture with 6 mm in diameter was placed just in front of the target. The H− ion beam was
swept using an electric deflector on which a saw-tooth voltage was applied. The target composition was
mounted on a thick copper block which was cooled by a Peltier element at a temperature of -1.9◦ C. The
integrated charge was 37460 µC.
1500

Counts per micro Coulomb

4000

Counts per 10 micro Coulomb

4500

A

3500
3000

B

2500
2000
1500
1000

1000

500

500

0

0
20 20.5 21 21.5 22 22.5 23 23.5 24
Bombarding Energy(lab) [MeV]Fig. 5. The yield of 6.13-MeV γ rays as a functionof the bombarding energy of 19 F ions

0

5
10
Run Number

15

Fig. 6. The yield of α-particles from theH(19 F,α2 ) reaction for every 10 µC accumulation
runs

The depth profile of the implanted hydrogen ions was measured by observing the yield of 6.13-MeV γ
rays from the H(19 F,α2 ) reaction. The yield curve is shown in Fig. 5. The peak A in Fig. 5 corresponds to
the 16.44 MeV resonance, while the peak B is due to the 17.6 MeV resonance. The shifts of these energies
are ascribed to the energy loss of incident 19 F ions in the titanium foil, because the surface of the titanium
foil exposed to the 19 F ions in the observation of γ rays and α particles was opposite to the surface on which
the H− implantation was performed.
The yield of reaction α-particles was measured every 10 µC with beam current of 50 nA. The results
shown in Fig. 6 suggests that the target seems to be rather stable for beam irradiation.
References[1] Hjörvarsson, J. Rydén, T. Ericson and E. Karsson, Nucl. Instr. Meth. in Phys. Res. B42 (1989) 257.
[2] L. Westerberg, L.E. Svensson, E. Karsson, M.W. Richardson and K. Lundström, Nucl. Instr. Meth. in
Phys. Res. bf B9 (1985) 49.
[3] K.A. Fletcher, Thesis, University of North Carolina at Chapel Hill (1993).

- 102 -

4.5

Status of Tsukuba AMS system

Y. Nagashima, R. Seki, D. Arai, T. Takahashi, and H. Kume1
Both of the beam transmission efficiency and the beam transmission stability are essentially
important for the AMS studies. Up to now, an ion source part and a particle detection lines have asufficient ability, but a tandem accelerator has insufficient
The energetic efforts of our AMS group are performed on the 36Cl measurements this year. The
36

Cl to 35Cl ratio of JCO samples are successively measured. The thermal neutron flux at the place of 10m

apart from a criticality accidental point is estimated to be 2.5*1011 cm-2. The results and some discussions
are stated in this annual report with a title of " AMS 36Cl measurement of JCO soils".
KEK concrete blocks for shielding radio-active beam are irradiated by very strong neutron flux
and are strongly activated. From a view point of human health, it is useful to know the radio activity of theconcrete blocks. Thus, 36Cl contents are measured as a function of a distance from the radio-active beam.
The results are listed and discussed in this annual report.
In order to know the influence of nuclear power plants to an environment, 36Cl in soils areextensively studied. The 36Cl is very suitable element to see the environmental changes for long term of
period by the human with the nuclear associated activities because of both very long halftime, about 0.3
million years, and very low natural abundance, less than 10-14 of 36Cl to 35Cl ratio. The soils are sampled in
the area of Tokai Village and in Tsukuba area as a reference. 36Cl to 35Cl ratio of Tokai samples are
preliminary about a hundred times larger than that of Tsukuba samples. The investigations are still
undergoing.
The development of a 129I measurement technique has been almost succeeded. The terminal
voltage of the 12UD tandem is stabilized by a slit current feedback system with the pilot beam method aswell as the 36Cl measurement. Fig. 1 shows an overall configuration of the 129I AMS system. Both 129I- andMoO2- are generated simultaneously in the ion source and are transported to the 12UD tandem through97

two successive mass separators. One is 120degree with 300mm radius mass separator and another one is
90degree magnet with 900mm radius of curvature. 127I- negative ions can be completely swept out and no127

I- makes an invasion upon the tandem. Therefore, there is no request of particle identification such as a

TOF detector for mass identification because a particle detector observes almost no 127I elements. The
AMS allows as isotopic sensitivity as low as one part in 1013 for 129I with 126MeV particle energy.
Thought the sensitivity is not so high, this number is enough to measure an iodine sample prepared froman environment because the background level of the sample is normally high, about 10-12. A decrease of atransmission coefficient of the particle passing through a carbon stripper foil (5µg/cm2) is not observed ina 3 hours measurement of 129I with 1nA 97MoO2- pilot beam. 127I- is measured by a Faraday-cup which islocated just after the 120degree magnet in the ion source system.

1

National Institute for Environmental Studies- 103 -

Fig. 1system configuration of 129I AMS- 104 -

4.6

AMS 36Cl measurements of KEK concrete shielding blocks

D. Arai, R. Seki, Y. Nagashima, T. Takahashi, T. Miura1, K. Bessho1, and S. Ishihama2
The 12GeV proton synchrotron of the KEK has been established for high energy physics and its
related experiments for about twenty years since it has been constructed. A variety of radio-nuclide havebeen created in the shielding concrete through both thermal neutron capture process and nuclear spallation
reactions. A quantitative information about radio-nuclides induced in the shielding concrete is very
important not only for evaluating radiation doses for persons who are working in the radioactive
circumstances, but also for planning the reconstruction of an accelerator facility. In this study, the depth
profiles of 36Cl long-lived radio-nuclei were measured for the shielding concrete exposed to secondary
particles in the 12 GeV proton EP2 beam-line at KEK.
A view of the EP2 beam line and sampling positions are shown in Fig. 1. The samples are coredout of the shielding concrete, 3m in length for the concrete wall with diameter of 5 cm at the 60cm from afloor, at the position marked B in the Fig. 1. The concrete shielding is constructed with three concrete
blocks. The thickness of each block is 1m. The most inner block is made from a normal concrete and aheavy concrete is a main component for the remaining two blocks.
The results of the depth profile of 36Cl are shown in Fig. 2 together with the results of the activity
measurements of 22Na, 54Mn, 60Co, and 152Eu [1]. The closed circles represent the results of the 36Cl
measurements as a function of depth. Ordinate shows the ration of 36Cl to 35Cl. The 36Cl/35Cl ration
decreases smoothly according to the deepness of the concrete shielding in the rage of 0cm to 200 cm. On
the other hand, the ratio is tremendously stepped up in the block No.3, from 200 cm to 300 cm. Thisphenomenon is also shown in the activity measurements of 22Na and 152Eu. Therefore, it is say that thehistory of the block No.3 is difference from those of block No.1 and block No.2. It is clear that the blockNo.3 might be used, in the past, in the field with strong radio-activity. The thermal neutron flux at thedepth of 3 cm is estimated 3.2*1014 cm-2. This number, the integration of the neutron yield for the twenty
years, corresponds to the yield of neutron for about 10 seconds of a typical nuclear reactor.

Reference
1] T.Miura, S.Takahara, S.Ishihama, N.Ohtsuka, and T.Kunifuda, KEK Preprint 99-68, (1999)

1

High Energy Accelerator Research Organization

2

Tokyo Nuclear Services Company- 105 -

Fig. 1The EP2 Beam Line of KEK Proton Synchrotron Accelerator.

Samples are drilled out from the concrete shielding blocks located at point B, black line.

1.E-07

1.E+01HEAVY
CONCRETENORMAL
CONCRETEHEAVYCONCRETE

1.E-081.E+0036Cl/35Cl

Mn-54

1.E-01

Co-60
Eu-152
1.E-10

1.E-02

1.E-11

1.E-03Block No.1

Block No.2

Block No.3

1.E-12
0

50

100

150

200

250

300

Depth from the Face of Concrete ShieldFig. 236

35

Cl/ Cl ratio of the concrete blocks as a fuction of depth
22
54
60
152
together with the activities of Na, Mn, Co, and Eu- 106 -

1.E-04350

Activity (Bq/g)

1.E-0936

Cl/35Cl

Na-22

4.7

AMS 36Cl measurement of JCO soil samples

D. Arai, R. Seki, Y. Nagashima, T. Takahashi, and H. Kume1
A critical nuclear accident at the nuclear fuel processing facility, JCO, in Tokaimura was one of
the most serious accidents in the history of nuclear power plants. Tremendous numbers of neutron
particles were released. For ecological and health reasons, several Japanese groups have estimated thetotal neutron flux from the site through by the analysis of short-lived radio-activated nuclei such as 198Au.
In order to sharpen the estimations, we commenced to measure the yield of 36Cl radioisotopes in thesamples being collected from the accident site in the last year. The neutron flux can be estimated from theratio of 36Cl to 35Cl because the 36Cl nuclei are created from 35Cl through a thermal neutron capture process,35

Cl(n,γ)36Cl. A 36Cl AMS technique [1] is the only available method for detecting very rare and very

long-live 36Cl radioisotopes.
We have been studying several soil samples that are collecting from the site of JCO. Adding to
the soil samples, both KCl and NaCl samples are also included in the study. AgCl is the most suitabletarget material for getting high and steady Cl negative ion beam in the ion source. Therefore, the soil
samples, as well as KCl and NaCl, are formed to AgCl by our sample preparation protocols. The
preparation method is described in somewhere [2]. The results of the 36Cl to 35Cl ratio measurements arelisted up on a Table 1. The 36Cl/35Cl ratio of the NaCl sample is very small, 1.6*10-14, and is almost thesame to the background level, 1*10-14. Therefore, the influence of the thermal neutron emerging by the
nuclear accident is limited within about 80m from the site of accident. On the other hand, the 36Cl yields ofthe soil-A and soil-I are about thousand times larger than the 36Cl yield of the NaCl sample. The thermal
neutron flux at 10m distances is estimated at 2.5*1011cm-2 from the result of the soil-B. Fig. 1 shows the36

Cl to 35Cl ratio as a function of distance. An inverse square of distance rule well explains the decrease of

the 36Cl/35Cl ratio according to the increase of the distance. The closed circles represent the estimation of
the 36Cl to 35Cl ratio by a Mon-te Car-lo simulation [3]. It seems that the calculation is systematically alittle bit smaller than the measurement. Thought the difference is systematic, we are trying to compare ourstandard AgCl sample to the standard one of Tokyo University. Up to now, this discrepancy is not well
explained. The investigation is still going on.

References
1] Y.Nagashima, R.Seki, T.Takahashi and D.Arai,

Nucl. Inst. & Meth., B172(2000)129-133.

2] D.Arai, R.Seki, Y.Nagashima, T.Takahashi, R.Mawatari, and H.Kume, UTTAC-68(2000)110.
3] T.Imanaka,

1

Private Communication.

National Institute for Environmental Studies- 107 -

Cl/35Cl (Atom Ratio)

Distance from the Accidental Site(m)

Soil-A(1.52±0.09)×10-11

2.5

Soil-I

-11

2.5

-11

10

-11

10

-12

15

-12

(3.68±0.06)×10

17

KCl

(5.6±0.5)×10

-14

56

NaCl

(1.6±0.3)×10-1480

SampleSoil-B
Soil-F
Soil-G
Soil-H

Table 136

36

(3.68±0.06)×10(1.10±0.02)×10(1.01±0.20)×10(6.79±0.12)×10

Cl contents in the JCO soils. Results are represented as the ratio of 36Cl to 35Cl.

Fig. 1 Ratio of 36Cl to 35Cl AMS measurement as a function of distance.

- 108 -

5. LIST OF PUBLICATIONSACCELERATOR AND EXPERIMENTAL FACILITIESK.Shima, S.Ishii, T.Takahashi, I.Sugai
Optimum thickness of carbon stripper foils in tandem accelerator in view of transmission and lifetime.
Nucl. Instrum. and Method A460 (2001) 233-239.
Appropriate carbon stripper foils of tandem accelerator in thickness, lifetime and transmission
K.Shima, S.Ishii, T.Takahashi, I.Sugai, and M.Oyaizu
SNEAP 1999, World Scientific Publ. (2000) , pp.121-132.
T.Ito, N.Hayashizaki, S.Matsui, K.Sasa, H.Schubert, S.Osvath, T.Hattori.
Acceleration test of TIT-IHQ linac for heavy ion irradiation.
Nuclear Instruments and Methods in Physics Research, B 161-163 (2000) 1164-1167.
T.Hattori, S.Matsui, N.Hayashizaki, H.Tomizawa, T.Yoshida, K.Sasa, S.Gates, K.Kawasaki, T.Niizaki,
K.Isokawa, T.Ito, M.Okamura.
Compact IH-APF type linac for PIXE and RBS analysis.
Nuclear Instruments and Methods in Physics Research, B161-163 (2000) 1174-1177.
S.Matsui, T.Hattori, N.Hayashizaki, H.Tomizawa, K.Sasa, T.Yoshida, K.Isokawa, T.Ito.
Compact IH-APF type linac for heavy-ion implantation.
Nuclear Instruments and Methods in Physics Research, B 161-163 (2000) 1178-1181.

NUCLEAR PHYSICS

Y. Tokimoto, H. Utsunomiya, T. Yamagata, M. Ohta, Y.-W. Lui, R.P. Schmitt, S. Typel, Y. Aoki, K. Ieki, K.
Katori
Coulomb breakup of 7Li for nuclear astrophysics
Phys. Rev. C63(2001) 035801
Y.Aoki, N.Okumura, T. Joh and Y.Honkyu
CDCC analysis of vector and tensor analyzing powers in 208Pb(d,d) elastic scattering at Ed=8 MeV
14th International Spin Physics Symposium (SPIN2000), Osaka, October 2000
T. Katabuchi, K. Kudo, K. Masuno, T. Iizuka, Y. Aoki and Y. Tagishi,
Polarization transfer for the 2H(d,p)3H reaction at =0at a very low energy,
14th International Spin Physics Symposium (SPIN2000), Osaka, October 2000

- 109 -

C.S.Lee, J.H.Ha, J.H.Lee, J.Y.Huh, J.C.Kim, C.-B.Moon, S.J.Chae, T.Komatsubara, T.Shizuma, H.Kimura,
K.Matsuura, K.Kato, Y.Sasaki, H.Ishiyama, K.Furuno
High-spin states of rotational bands built upon nu i-13/2 in 166Lu
Eur.Phys.J. A8 (2000) 1-3.
C.-B.Moon, T.Komatsubara, K.Furuno
Rotational Bands in 122Cs
Nucl.Phys.A674, 343-356 (2000), Erratum Nucl.Phys. A678 (2000) 457.
Y.H.Zhang, T.Hayakawa, M.Oshima, Y.Toh, J.Katakura, Y.Hatsukawa, M.Matsuda, N.Shinohara, T.Ishii,
H.Kusakari, M.Sugawara, T.Komatsubara
Observation of signature inversion in odd-odd 178Ir
Eur.Phys.J. A8 (2000) 439-442.
A.A.Pasternak, Y.Sasaki, A.D.Efimov, V.M.Mikhailov, T.Hayakawa, Y.Toh,M.Oshima, Y.Hatsukawa,
J.Katakura, N.Shinohara, Z.Liu, K.Furuno
DSA lifetime measurements and structure of positive-parity bands of 120Xe
Eur.Phys.J. A9 (2000) 293-297.

HIGH ENERGY NUCLEAR PHYSICS

L. Ahle, (A. Kumagai, K. Kurita, H. Sako, Y. Miake, S. Ueno-Hayashi, K. Yagi), et.al.
Particle production at the AGS: an excitation function
Nucl.Phys.A661(1999) 472-475.
M.M. Aggarwal, (T. Chujo, R. Higuchi, S. Kato, M. Kurata, K. Kurita, Y. Miake, Y.Miyamoto, S.
Nishimura, H. Sako, S. Sato, K. Yagi, Y. Yokota), et.al.,
Elliptic emission of K+ In 158-A-GeV Pb + Pb collisions
Nucl.Phys.A661 (1999) 464-467.
T. Peitzmann, (T. Chujo, R. Higuchi, S. Kato, M. Kurata, K. Kurita, Y. Miake, Y.Miyamoto, S. Nishimura,
H. Sako, S. Sato, K. Yagi, Y. Yokota), et.al.,
Recent results from the WA98 experiment
Nucl.Phys.A661 (1999) 191-197.
M.M. Aggarwal, (T. Chujo, R. Higuchi, S. Kato, M. Kurata, K. Kurita, Y. Miake, Y.Miyamoto, S.
Nishimura, H. Sako, S. Sato, K. Yagi, Y. Yokota), et.al.,Central Pb + Pb collisions at 158/A– GeV/c studied by pi-pi interferometry
Eur.Phys.J. C16 (2000) 445-451.

- 110 -

M.M. Aggarwal, (T. Chujo, R. Higuchi, S. Kato, M. Kurata, K. Kurita, Y. Miake, Y.Miyamoto, S.
Nishimura, H. Sako, S. Sato, K. Yagi, Y. Yokota), et.al.,Collective flow and HBT in Pb + Pb collisions at the CERN-SPS
Nucl.Phys.A663 (2000) 729-732.
Tapan K. Nayak, (T. Chujo, R. Higuchi, S. Kato, M. Kurata, K. Kurita, Y. Miake, Y.Miyamoto, S.
Nishimura, H. Sako, S. Sato, K. Yagi, Y. Yokota), et.al.,
Search for disoriented chiral condensates in 158/A-GeV Pb + Pb collisions
Nucl.Phys.A663 (2000) 745-748.
M.M. Aggarwal, (T. Chujo, R. Higuchi, S. Kato, M. Kurata, K. Kurita, Y. Miake, Y.Miyamoto, S.
Nishimura, H. Sako, S. Sato, K. Yagi, Y. Yokota), et.al.,++production in 158-A-GeV 208Pb + 208Pb interactions at the CERN SPS.
Phys.Lett.B477 (2000) 37-44.
L. Ahle, (T. Chujo, A. Kumagai, K. Kurita, Y. Miake, H. Sako, S. Ueno-Hayashi, K. Yagi), et.al.,
An excitation function of K- and K+ production inAu + Au reactions at the AGS
Phys.Lett.B490 (2000) 53-60.
M.M. Aggarwal, (T. Chujo, R. Higuchi, S. Kato, M. Kurata, K. Kurita, Y. Miake, Y.Miyamoto, S.
Nishimura, H. Sako, S. Sato, K. Yagi, Y. Yokota), et.al.,Three pion interferometry results from central Pb + Pb collisions at 158-A-GeV/c
Phys.Rev.Lett. 85 (2000) 2895.
M.M. Aggarwal, (T. Chujo, R. Higuchi, S. Kato, M. Kurata, K. Kurita, Y. Miake, Y.Miyamoto, S.
Nishimura, H. Sako, S. Sato, K. Yagi, Y. Yokota), et.al.,Scaling of particle and transverse energy production in 208Pb + 208Pb collisions at 158-A/GeV
Eur.Phys.J.C18 (2001) 651-663.
M.M. Aggarwal, (T. Chujo, R. Higuchi, S. Kato, M. Kurata, K. Kurita, Y. Miake, Y.Miyamoto, S.
Nishimura, H. Sako, S. Sato, K. Yagi, Y. Yokota), et.al.,
Observation of direct photons in central 158-A/GeV 208Pb + 208Pb collisions
Phys.Rev.Lett. 85 (2000) 3595.
Y. Miake,
Delta++ production & Directed and Elliptic Flow in 158A GeV Pb + Pb collisions
XXXth International Conference on High Energy Physics, July 27 -August 2, 2000, Osaka, Japan- 111 -

ATOMIC AND SOLID STATE PHYSICS, AND CLUSTER SCIENCE

K.Awazu, S.Ishii and K.Shima
Creation of individual holes in SiO2 on Si by swift heavy ion bombardment followed process
2000 Intern. Microprocesses and Nanotechnology Conference (MNC 2000) July, 2000, Tokyo
K.Awazu, S.Ishii , K.Shima
Formation of individual holes in amorphous SiO2 by swift heavy-ion bombardment followed by wet
and dry etching.
Jpn. J.Appl. Phys. 2000; 39: 7058-7059.
K.Shima and S.Nagai
Foil thickness for ions attaining charge equilibrium.
4thAsian International Seminar on Atomic and Molecular Physics, October 2000, Taipei,
J. Chinese Chem. Soc. 48 (2001) no.3A, 178-183.
Ion-induced electron emission from Si crystal targets covered with noncrystalline Si layers, Hiroshi Kudo,
Naoki Nakamura, Kohki Shibuya, Kazumasa Narumi, Shunya Yamamoto, Hiroshi Naramoto, Koji
Sumitomo, Seiji Seki,
Nucl. Instrum. & Methods 168 (2000)181-191.
H. Kudo, S. Seki, K. Sumitomo, K. Narumi, S. Yamamoto, H. Naramoto,Ion-induced electron measurements using crystal targets overlaid with noncrystalline layers,
Nucl. Instrum. & Methods B164-165 (2000) 897-902.
H.Mizubayashi, G.Nishikori and H.Tanimoto,High-cycle fatigue properties of modified 316 stainless steels under in-site thermal-pulses,
Materials Transactions, 42 (2001)151-156 .
I. Arai, H. Sasaki, T. Shimayama and S.M. Lee,
Dissociation of Si clusters produced by bombardment of 6keV Xe atoms,
Transactions of the Materials Research Society of Japan, 25 (2000)947-950.
C. K. Chung, I. Arai, S. M. Lee,
Critical size of metal cluster in a metal cluster source controlled with a magnetron,
Transactions of the Materials Research Society of Japan, 25 (2000) 955-958.
T. Kurita, M. Imanaka, T. Nakagawa, M. Kidera and S.M. Lee,
Production of highly charged Xe ions from liquid He free super conducting electron cyclotron resonanceion source,
Jap. J. Appl. Phys. 40, 5A(2001).

- 112 -

I. Arai, C.K. Chung, H. Sasaki and S.M. Lee,
Physical processes of cluster formation in gas aggregation and fast atom bombardment
Transactions of the Materials Research Society of Japan, 26 (2001).
I. Arai,
Scaling observed in abundance spectra of 3D transition metal cluster produced by sputtering
Desorption 2000 Conference, Saint-Malo, France, 3-7 September 2000.

ION BEAM APPLICATION

M. Kurosawa and S. Murao
Improvement of micro-PIXE to quantify geochemical thick target.
Bull. Geol. Surv. Japan, 51(2000) 325-328.
D.Yamazaki, T.Kato, H.Yurimoto, E.Ohtani and M.Toriumi.
Silicon self-difffusion in MgSiO3 perovskite at 25 GPa.
Physics of the Earth and Planetary Interiors, 119 (2000) 299-309.
T. Kato, H. Terasaki and T. Kubo
Transport properties of earth material-new insights on science of the Earth's interior-,
J. Geography, 109 (2000) 868-873.
R.Seki et al,
The JCO criticality accident at Tokai-mura Japan: an overview of the sampling campaign and peliminary results,
J. Environmental Radioactivity 50 (2000) 3-14.
Y.Nagashima et al,
Status of 36Cl AMS system at the University of Tsukuba,
Nucl. Instrum. Methods B172 (2000) 129-133.

- 113 -

6. THESES
Ph. D. Theses
N.Okumura
C.K. Chung
T. Kurita
N.Nishiguchi
S.Sakai
T.Nakajou
S.Satou
M. Sc. Theses
J. Hirose
S. Shimakura
K.Sawada
K.Kudou
K.Masuno
R.AraiI.Amemiya
K.Kogure
J.Hasegawa
M.OhiraT.Kinosita
D.Hakozaki
M.Aizawa
K. Satou
K. Yamada

Total reaction cross section of p+28Si system near neutron threshold energy
Cluster formation and growth in a metal cluster source controlled with a magnetron
and a gas aggregation cell
Development of an ECR ion source using liquid-helium-free superconducting
solenoid coils
Crystal structures and magnetic properties of the two-dimensional spin-1/2 system
MVnO2n+1
Physical Property of High-Density Nanocrystalline Gold
Study of single particle spectra and two particle correlation in Au+Au collisions at 4 11 AGeV
Study of ∆++ resonance abundance in 158 A GeV Pb + Pb collisions at CERN-SPS

Energy dependence of cluster production by sputtering
Secondary electron emission of clusters and their detection efficiency
Development of of the proton polarimeter for double scattering experiment
Measurement of polarization transfer coefficient in the 2H(d,p)3H reaction at incident
deuteron energy of 90 keV
Analyzing powers for the continuous spectrum region
Crystal structures and magnetic properties of δ-phase AgxV2O5
Basic properties of the insertion-electrode system Li1+xV3O8
Nuclear magnetic resonance of the mixed-valence system Cu7V6O19
Crystal structures and magnetic properties of Tl0.5V2O5Structure-sesitive ion-induced electron spectroscopy of damaged Si
Structure-sensitive ion-inducedAuger electron spectroscopy of layered crystals
The prototype production and evaluation of Pestov Spark Counter for high energy
nuclear experiments
Single particle measurement of pion, kaon, and proton at 158AGeV Pb+Pb collision
Measurements of fusion cross sections in the reactions of 82Se +138Ba and 82Se +134Ba
Measurement of the magnetic moment of the second-excited state in 165Ho withtransient magnetic field- 114 -

7. SEMINARS
Date
2000
May. 17
May. 24
May. 24
May. 31
June. 7
June. 14
June. 28
Sept. 6
Sept. 10
Sept. 27
Oct. 11
Oct. 25
Nov. 1
Nov. 8

Nov. 22
Dec. 1
Dec. 15
Dec.20Dec. 27

Speaker

and

Title

H.Miyatake (KEK) ; Future plan of the nuclear physics group at KEK
T.Katabuchi (Univ. of Tsukuba); Polarization transfer for the 2H(d,p)3H reaction at very low
energies
Y.Tagishi (Univ. of Tsukuba) ; Direct detection of alpha particles emitted fromdaughter nucleus of random and thoron
K.Yabana (Univ. of Tsukuba) ; Reaction mechanisms of Halo Nuclei
T.Nakagawa (RIKEN); New method for the trace element analysis using ECR ion
source and heavy ion
Y.Hatsukawa (JAERI); Application of the method of multidimensional spectrum toactivation analysis
S.M.Lee (Univ.of Tsukuba); Nuclear physics by femtosecond laser and cluster
T.Kurita (Univ.of Tsukuba) ; Development of ECR ion source using liquid-He-freeSuperconducting solenoid coils
I.Arai (Univ.of Tsukuba) ; Report on desorption 2000 conference
G.Vourvopoulos (Western Kentucky Univ.); Pulsed fast/thermal neutron analysis : a technique
for the detection of explosives and drugs
Chun-Kyun Chung (Univ. of Tsukuna);Cluster formation and growth in a metal cluster source
controlled with a magnetron
S.Satou (Univ. of Tsukuba); Study of ∆++ resonannce abundance in 158 A GeV Pb+Pb
collisions at CERN-SPS
T.Itahashi (Osaka Univ.) ; Feasibilities of tritium acceleration and its perspectives
Xiao-Hong Zhou (IMP, Lanzhou) ; Present status of nuclear structure studies in
IMP at Lanzhou
Shu-Xian Wen (CAEI, Beijing); Present status of nuclear structure studies in CAEI at
Beijing
Yu-Hu Zhang (IMP, Lanzhou) ; Study of high-spin states in doubly odd nuclei
aroundA=160 180
Y.Tagishi (Univ. of Tsukuba) ; High-Sensitive Detector for Environmental Radon
K.Yoshinari (Central Research Lab., Hitachi Ltd.) ; Numerical study of ion behaviors
in radiofrequency quodrupole mass spectrometer
Y.Honkyu (Univ. of Tsukuba) ; Measurement of the proton spectrum in deuteronbreak-up reaction,
K. Kudo (Univ. of Tsukuba); Polarization transfer coefficient Kyy' in the 2H(d,p)3H
reaction at θ= 0° at very low energies,
K.Yamada (Univ. of Tsukuba); Measurement of the magnetic moment of the secondexcited state in 165Ho with Transient Magnetic Field,
J.Hirose (Univ. of Tsukuba); Energy dependence of cluster production by means of
Sputtering,- 115 -

2001
Jan. 10Jan. 17
Jan. 18
Jan. 24

Jan. 31

Feb. 8March 13r

r

K.Masuno (Univ. of Tsukuba); Analyzing powers in the continuum of the ( p ,α) and ( d ,α)reactions at E=20MeV
K.Satou (Univ. of Tsukuba); Measurements of Fusion Cross Sections in the Reactionsof 82Se + 138Ba and 82Se + 134Ba
T.Shinozuka (Tohoku Univ.) ; Renewal of the cyclotron accelerator and future plan ofexperiment at the Cyclotron and RI Center at Tohoku Univ.
T.Kurita (Univ. of Tsukuba); Development of an ECR ion source using liquid-heliumfree superconducting solenoid coils
D.Hakozaki (Univ. of Tsukuba); The prototype production and evaluation of Pestov SparkCounter for high energy nuclear experiments,
K.Sawada (Univ. of Tsukuba); Proton polarimeter using a liquid helium target,
S.Shimakura (Univ. of Tsukuba); Secondary electron emission caused by clusters and theirdetection efficiency,
M.Aizawa (Univ. of Tsukuba); Single particle measurement of pion, kaon, and proton
at 158AGeV Pb+Pb collision,
N.Horikawa (Nagoya Univ.) ; Polarized target for d-d scattering and dynamic
nuclear polarization
M.Matoba (Kyushu Univ.) ; Utilization and future of accelerators inJapanese national universities- 116 -

8. SYMPOSIUM
25th Anniversary of the Foundation of the UTTAC-------Ion beam science using tandem accelerator ------December 12-13, 2000
University Hall, University of Tsukuba
Opening
25 years of UTTAC, K.Furuno (Univ. of Tsukuba)
Elemental analysis I
Application of PIXE to earth science----micro analysis of fluid inclusion, M.Kurosawa(Univ. of Tsukuba)
Micro-elemeental analysis using multiple -ray detection methods, Y.Tou (JAERI)Elemental analysis II
Environmental research byAMS at NIES-TERRA, Y.Shibata (NIES)AMS at the MALT of Tokyo University, H.Matsuzaki (Tokyo University)
Present status of AMS at the University of Tsukuba, Y.Nagashima (CMTN)
Development of AMS system at Kyushu University, S.Mitarai (Kyushu Univ.)
Nuclear Phsics I
High spin studies of nuclei around A=120 at the Tandem Accelerator center of the University of Tsukuba(UTTAC), Chang Bum Moon (Hoseo Univ.)
Projectile coulomb excitation of Ge and Se isotopes, T,Hayakawa (JAERI)
Meson and quark degrees of freedom in the nucleus detected through the nuclear decay, K.Minamisono(Osaka Univ.)
Symmetry structure of mirror nuclei studied in M1 and GT transitions, Y.Shimbara (Osaka Univ.)
Nuclear Phsics II
A coulomb breakup experiment, H.Utsunomiya (Konan Univ.)
Physics on one-nucleon transfer reactions in several tens MeV energy region, M.Matoba (Kyushu Univ.)
Current and near future experiments by using tandem accelerator, Y.Aoki (Univ. of Tsukuba)
Nuclear reaction using an ion source, Y.tagishi (Univ. of Tsukuba)
Some historical topics around the period of the birth of UTTAC, T.Mikumo (emeritus prof. of Univ. of
Tsukuba)

Atomic and Solid-State Physics I
Ion-Induced Electron Emission from Crystalline Solids, H.Kudo (Univ. of Tsukuba)
Electronic excitation effects in oxide superconductors irradiated with high energy ions, N.Ishikawa(JAERI)
Charge-state equilibration of fast ions passing through a carbon foil and a single C60 molecule, A.Itoh(Kyoto Univ.)- 117 -Atomic and Solid-State Physics II
Formation of individual holes in amorphous SiO2 by swift heavy-ion bombardment followed by wet anddry etching, K.Awazu (Electrotechnical Lab.)
Local structure of GaN doped with Eu, S.Morishima (Univ. of Tsukuba)
Enhanced conductivity in polymer materials irradiated with proton beams, S.Matumoto (Chiba Inst.
Techmology)
Ion Beam Techhnology I
Progress of cluster physics at UTTAC, I.Arai (Univ. of Tsukuba)
Measurement of mass distribution of gold clusters, T.Mizota (GIRI, Nagoya)
Development of beam, target and analyzerfor astro-nuclear experiment, K.sagara (Kyushu Univ.)
Development of monoenergetic neutron source using the 1H(13C, n) reaction in the MeV region,
Y.Watanabe (Kyushu Univ.)
Ion Beam Techhnology II
Frontier of long-lived cluster and hybrid carbon stripper foils for high energy, high intensity ion beams,
I.Sugai (KEK)A beam-foil interaction study with lazer displacement meter, I.Katayama (KEK)
Acceleration of microparticles (dsust) and its application, H.Shibata (Tokyo Univ.)

Concluding Remarks
Science using beams of nucleus, K.Katori (emeritus prof. of Osaka Univ.)- 118 -

9. LIST OF PERSONNEL
Accelerator Center
K. Furuno
K.Shima
T.Komatsubara
K.SasaT.Katabuchi
S.Ishii
H.Kimura
H.Oshima
Y.Tajima
T.Takahashi
Y.Yamato
K.Itoh
Li Tian-Xin
Y.Kamiyama
O.Akutsu

Director, Professor
Associate Professor
Assistant Professor
Assistant Professor
ResearchAssociate
Mechanical Technician
Computer Technician
Electric Technician
Mechanical Technician
Electric Technician
Electronics Technician
Research Fellow
Research Fellow
Accelerator Support Staff
Administrative Stuff

Steering Committee
K.Furuno
Y.Kajiwara
R.Kanzaki
T.Komatsubara
H.KudoS.M.Lee
M.OnodaR.Seki
K.ShimaY.Tagishi
K.Yabana
K.Yasuoka

Chairperson, TandemAccelerator Center
Inst. of Geoscience
Inst. of Biological Sciences
TandemAccelerator Center,Inst. of Applied Physics
Inst. of Physics
Inst. of Physics
Inst. of Chemistry
TandemAccelerator Center
Inst. of Physics
Inst. of Physics
Inst. of Basic Medical Sciences- 119 -

Scientific Guests and Fellows
C.B.Moon
Zhang Yu-Hu
K.Awazu
M.Matoba
Y.HataI.Daitou
M.Takeuchi
T.Mizota
S.Matsumoto
H.KumeT.Ishihara

Hoseo Univ., Korea
IMP, Lanzhou
Electrotechnical Lab.
Kyushu Univ.
JAERI
Nagoya Univ.
Nagoya Univ.
GIRI, Nagoya
Chiba Inst. Technology
National Inst. For Environmental Studies
KEK

Research Members
Inst. of Physics
Y.AokiT.Komatsubara
S.Satou

I.Arai
S.M.Lee
K.SasaS.EsumiY.MiakeY.Tagishi

K.Furuno
N.Okumura
T.Une

T.Katabuchi
M.OnodaT.Katou

M.Kurosawa
E.KitaH.KudoK.Shima

H.Mizubayashi

K.Takita

H.Tanimoto

Inst. of Geoscience
R.AnmaInst. of Applied Physics
T.Azuma

A.UedonoInst. of Chemistry
R.SekiInst. of Materials Science
H.IkedaT.KoyanoCollege of Medical Technology and Nursing
Y.Nagashima

Tandem Accelerator Center
K.Itoh

Li Tian-Xin

Venture Business Lab.
T.Miyazaki- 120 -

Graduate Students
Doctoral Degree Programs in Physics
Ma Ying-Jun
C.K.Chung
T.Kurita
N.Kawachi
S.G.LeeJ.Hirose
K.Takeda

T.Jou
K.Masuno
R.AraiM.Yamaguchi
M.Suzuki
M.Ono,

H.Sasaki
T.Nakajou
M.Imanaka
H.Tsuruoka

N.Nishiguchi
Y.Sasaki
K.Satoh
Y.Takechi

K.Asami

S.Sakai

K.Kogure
S.Shimakura
M.Oohira
A.Oyadomari
Y.Mihara

K.Sawada
S.Shimano
T.Kinoshita
D.Kasuga

M.Shioda
T.OkabeA.Danmura
T.BannoT.Suguri

T.Furui
N.kajiya
H.Masui
Y.Kunieda
S.Numazawa

Doctoral Degree Programs in Engineering
K.Ono
N.Ookubo

N.UmedaLi Changqing

K.Suzuki

Doctoral Degree Programs in Education
T.Tsukada

Master's Degree Programs in Sciences and Engineering
T.Sakai
M.Aizawa
D.Hakozaki
S.Yokose
K.KanbeY.Honkyu
Y.Akutsu
J.Hasegawa
T.Iizuka
M.Muramatsu

I.Amemiya
K.Kudou
K.Yamada
A.Negishi
Y.KoudaMaster's Degree Programs in Environmental Sciences
D.Arai

Undergraduates
M.Ishizuka
M.Aramaki
Y.Kuroki
H.ImaiM.Higurashi
M.Nakazumi

M.Yoshimoto
K.Teranishi
S.Sakai
K.Sekine
I.AranoM.ImonN.Umezawa
M.Shindou
A.Tokunaga
W.Iwazaki- 121 -