UTTAC-77, 2008

UTTAC
ANNUAL REPORT 2007

TANDEM ACCELERATOR COMPLEX
Research Facility Center for Science and Technology
University of Tsukuba

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

UTTACANNUAL REPORT 2007
April 1, 2007 – March 31, 2008

UTTAC-77 2008

Executive Editor: Hiroshi Kudo
Editors: Yoshihiro Yamato, Daiichiro Sekiba, Kimikazu Sasa, Tetsuro Komatsubara

UTTAC is a series of issues, which include annual reports of
Tandem Accelerator Complex, Research Facility Center
for Science and Technology, University of Tsukuba.
The issues may also include irregular reports written by English.
Copyright © 2008 by Tandem Accelerator Complex, Research Facility Center
for Science and Technology, University of Tsukuba and individual contributors.
All reports are written on authors’ responsibility and thus the editors are not liable
for the contents of the report.

Tandem Accelerator Complex, Research Facility Center for Science and Technology,
University of Tsukuba
Tennodai 1-1-1, Tsukuba, Ibaraki 305-8577, Japan
http://www.tac.tsukuba.ac.jp/
annual@tac.tsukuba.ac.jp

PREFACE
This annual report covers researches carried out at University of Tsukuba Tandem Accelerator
Complex (UTTAC) during the fiscal year 2007 (1 April 2007 ∼ 31 March 2008). The topics include
not only accelerator-based researches using the 12MV Pelletron and 1MV Tandetron accelerators, butalso closely related researches to UTTAC.
July 15, 2008
Editors-i-CONTENTS

1. ACCELERATOR AND EXPERIMENTAL FACILITIES
1.1

Accelerator operation 2007 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1

1.2

Status of the Tsukuba AMS system . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4

1.3

Developments of ERCS hydrogen analysis . . . . . . . . . . . . . . . . . . . . . . . . .

6

2. NUCLEAR PHYSICS
2.1

Production of radioactive nuclear beam of 8 Li and its in-flight identification . . . . . . . .

2.2

118 Sn(d,p) reaction in search for Coulomb stripping of deuteron V

2.3

Measurement of the time response in Hybrid Photo Detector II . . . . . . . . . . . . . . . 13

2.4

Study of nuclear synthesis of 26 Al by gamma ray spectroscopy . . . . . . . . . . . . . . . 15

2.5

Nuclear structure of supernova neutrino-process isotope 138 La . . . . . . . . . . . . . . . 179

. . . . . . . . . . . . . 11

3. MATERIALS AND CLUSTER SCIENCE
3.1

Synthesis of elongated and oriented gold nanorods in silica by irradiation of swift heavy ion 19

3.2

Characterization of Er-doped GaN by heavy ion RBS . . . . . . . . . . . . . . . . . . . . 21

3.3

Dependence of the vicinage effect on interatomic spacing of carbon clusters . . . . . . . . 23

3.4

Point defects in Er-doped GaN probed by means of positron annihilation . . . . . . . . . 24

3.5

Rutherford backscattering spectroscopy on Pt-absorbed HOPG surface . . . . . . . . . . 26

3.6

Möessbauer study of sub-micron sized Fe3 O4 particles and NH3 nitrized particles . . . . . 28

3.7

Molcular dynamics calculation of water clusters . . . . . . . . . . . . . . . . . . . . . . 30

3.8

Simulation of gas aggregation cell by DSMC method . . . . . . . . . . . . . . . . . . . . 32

4. ACCELERATOR MASS SPECTROMETRY
4.1

Cosmogenic 36 Cl measurements in the Dome Fuji ice core, Antarctica . . . . . . . . . . . 33

4.2

Residence times of spring waters on the foot of Mt. Fuji, estimated from bomb-produced
36 Cl. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

4.3

Measurement of in situ-produced cosmogenic 36 Cl in calcite . . . . . . . . . . . . . . . . 38

4.4

Depth profile of 36 Cl/35 Cl induced in the thick concrete shield in EP-1 beam line at the
12-GeV proton synchrotron facility, KEK . . . . . . . . . . . . . . . . . . . . . . . . . . 40

4.5

Chlorine-36 in Gibeon iron meteorite . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

5. INTERDISCIPLINARY RESEARCH
5.1

Development of radiation environment monitor on board spacecraft . . . . . . . . . . . . 43

5.2

Micro-PIXE analysis of rare-earth elements in monazite . . . . . . . . . . . . . . . . . . 45

5.3

Ion induced nanoparticle formation in N2 /H2 O/SO2 . . . . . . . . . . . . . . . . . . . . . 48

6. LIST OF PUBLICATIONS
6.1

Journals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

6.2

International conferences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

- iii -

7. THESES

53

8. SEMINARS

54

9. SYMPOSIA

55

10. LIST OF PERSONEL

57- iv -

1.
ACCELERATOR AND EXPERIMENTAL FACILITIES1.1

Accelerator operation 2007

K. Sasa, S. Ishii, H. Kimura, H. Oshima, Y. Tajima, T. Takahashi, Y. Yamato, T. Komatsubara, D. Sekiba
and H. Kudo.
The University of Tsukuba Tandem Accelerator Complex (UTTAC) operates the 12UD Pelletron
tandem accelerator and the 1 MV Tandetron accelerator. The total service time of the UTTAC
multi-tandem accelerator facility was 145 days (3,480 hours) in the fiscal year 2007. In this year we havestarted on the new project “Open Advanced Facilities Initiative for Innovation (Strategic Use by Industry)”,which is supported financially by the Ministry of Education, Culture, Sports, Science and Technology. In
this project, 5 industrial research programs were progressed using 18 % (624 hours) of the total service
time by industrial users.
The 12UD Pelletron tandem accelerator
During the total service time, the accelerator operating time and the experimental beam time were1748.3 and 1312.5 hours, respectively. The operating time was about 93.2 % relative to that in 2006.
Figure 1 shows the accelerator operation hours per month. The beam time histogram with respect to theterminal voltage is shown in Fig.2. Figure 3 represents the percentage of the operation hours for the three
ion sources and ion species.
Machine operation hours

200
180
160
140
120
100
80
60
40
20
0

2007
Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

2008
Jan

Feb

Mar

Fig.1. Accelerator operation hours per month for the fiscal year 2007.
11 MV

Terminal voltage

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

200

400

600

800

1000

1200

Beam hours

Fig.2. Beam time histogram as a function of the terminal voltage in the fiscal year 2007.

1

SputterIon Source

AMS
Ion Source1H
29.1 %

36

Cl
33.7

2

35

7

Cl
2.3

Li
4.7
12

H
2.0

12

C
1.0

C
2.8

3

He
6.8

16

O
8.9

79

Polarized
Ion Source

Br
4.7

197

Au
2.5

28

63

Cu
0.1

56

Fe
0.4

35

Cl
0.8

Si
0.2

Fig.3. Percentage of the operation hours for the three ion sources and ion species for the fiscal year 2007.
Accelerator
Science
0.3

Innovation
11.7

Developments(Instruments andDetectors)
3.1

Accelerator Mass
Spectrometry(AMS)
37.8 %

Hydrogen Analysis
5.0
Nano Science(Heavy Ion
Irradiation)
5.9

Heavy Ion RBS
8.1

Atomic Physics(Droplet
Formation)
11.0

Nuclear Physics
17.1

Fig.4. Percentage of the experimental beam time for the running research fields for the fiscal year 2007.
In the year of 2007, 73 research programs were performed and a total of 648 researchers used the
12UD Pelletron tandem accelerator. Fig.4 shows the percentage of the experimental beam time for therunning research fields with the 12UD Pelletron tandem accelerator. The AMS study has been the research
field of the largest beam time ratio since 2006.
A cooling system of the SF6 gas compressor was broken and repaired in 2007. We could not transfer
SF6 gas between the accelerator main tank and the storage tank until January 2008. The scheduled
maintenance in the spring 2008 was started on March 13. We have a plan to exchange the corona needle tothe divided resistor at the next scheduled maintenance. At this maintenance time, we performed anefficiency test on the divided resistor with the terminal voltage of 3 MV by using 3 accelerator column
units. The results of the efficiency test demonstrated that the divided resistor had a good performance.

2

The 1MV Tandetron accelerator
During the total service time, the accelerator operating time and the experimental beam time were433.1 and 230.0 hours, respectively. The operating time was about 66.4 % relative to that in 2006. In theyear of 2007, 38 research programs were performed and a total of 144 researchers used the 1 MV
Tandetron accelerator. Figure 5 shows the percentage of accelerated ions with the 1MV Tandetron
accelerator. Figure 6 shows the percentage of the experimental beam time for the running research fields.
The main research field of the 1MV Tandetron accelerator was cluster beam studies, in which a carbon
cluster beam (Cn<8) was mainly used. The 1MV Tandetron accelerator was also used for trace-element
analysis with Particle Induced X-ray Emission (PIXE), Rutherford Backscattering Spectroscopy (RBS),Elastic Recoil Detection Analysis (ERDA) and ion implantation.

C-cluster53.6

H35.5 %

He 6.8
O 2.1

C 2.0

Fig.5. Percentage of accelerated ions with the 1MV Tandetron accelerator for the fiscal year 2007.

Education
0.4

Ion
implantation
2.1

Innovation
9.1

RBS･ERDA
8.8

Radiation
dosimetry
10.4

Clusterphysics
53.6 %

PIXE
15.6

Fig.6. Percentage of the experimental beam time for the running research fields with the 1MV
Tandetron accelerator for the fiscal year 2007.

3

1.2

Status of the Tsukuba AMS system

K. Sasa, Y. Nagashima, T. Takahashi, K. Sueki, Y. Tosaki, M. Tamari, T. Oki, S. Mihara, Y. Guan, Y.
Yamato, M. Matsumura, K. Bessho 1 , H. Matsumura1, T. Miura1, K. Masumoto1 and Y. Matsushi 2
The Tsukuba AMS system has been able to measure environmental levels of long lived radioisotopes of
14

C, 26Al, 36Cl and 129I by employing a molecular pilot beam method[1]. In addition, we have beendeveloping 32Si and 41Ca AMS systems for future research programs. In the year of 2007, we measured
about 500 samples with the Tsukuba AMS system. Table 1 shows research programs and the number ofsamples performed by the Tsukuba AMS system.
Table 1 Research programs and the number of samples by the Tsukuba AMS system in the year of 2007.
AMS research programs

Target material

Organization

Number36

Cl-AMS36
Cl in the Dome Fuji ice core,
Univ. of Tsukuba
Antarctic ice core
Antarctica
36
Cl in the radiation shield at
KEK
Concreteaccelerator facilities
36
Bomb-produced Cl as a tracer in Hydrological samples (ground
Univ. of Tsukuba
groundwater
water, rain water)
In-situ 36Cl for denudation rates of karst
The Univ. of Tokyo
Limestone
landform
36

Cl in meteorite

Meteorite

Tokyo Metro. Univ.

Development of the chemical procedure
Environmental samples (soil) Univ. of Tsukuba
for sulfur reduction
36
Cl-AMS research and development KN Standard sample
Univ. of Tsukuba
36

Cl standard

KN Standard sample

-

181
48
43
38
8
32
13
90

14

C-AMS
14

C-AMS for an efficiency test

Standard sample

Univ. of Tsukuba

5

SiO2

Univ. of Tsukuba

2

32

Si-AMS
32

Si-AMS research and development

36

Cl-AMS

The performance of 36Cl AMS was improved in AMS technique and system, such as a sample preparation
technique, upgrade of the ion source and a new data acquisition system. Beam currents of 35Cl- and 37Clwere able to be measured by the multi-Faraday cup set to the low energy side with a PC control system.
Typical beam current of 35Cl- was 10 μA. 36Cl14+ with the energy of 100 MeV was detected by a gas ΔE-E
detector.
For 36Cl AMS, the standard deviation of the fluctuation for the 36Cl/Cl ratio is within ± 2 %, and the1
2

Radiation Science Center, High Energy Accelerator Research Organization
Micro Analysis Laboratory, Tandem Accelerator, The University of Tokyo4

effective detection limit is better than 5 × 10−15. In
the year of 2007, we changed the standard
Measured 36Cl/Cl

reference sample to the KN standard[2] provided by
Prof. Nishiizumi, UC Berkeley, instead of theinternal standard sample. Fig. 1 shows the linearityof the measured 36Cl/Cl ratios for the KN standard(36Cl/C=1.00 × 10−11, 5.00 × 10−12, 1.60 × 10−12 and5.00 × 10−13) for 5 minutes measurements with 4
times. The measured data was normalized by the
KN standards 36Cl/Cl

standard of 36Cl/C = 1.00 × 10−11. The result shows

Fig. 1 Linearity of the measured 36Cl/Cl ratios

a good linearity with the statistical error of ±for the KN standard.

1–2 %.

400

14C standard

300

14C5+ (35 MeV)

200

7Li

ΔE channel number

ΔE channel number

400

SiO2 blank target

300

100
32S11+ (81 MeV)

200
Meas. Time: 10 min.
100

200
300
E-ΔE channel number

400

100
200
E-ΔE channel number

Fig. 2 14C5+ (35 MeV) spectrum of the standard sample.

300

Fig. 3 Spectrum of the SiO2 blank target.

14

C-AMS

We examined the performance of 14C AMS. The terminal voltage was selected at 7 MV, and 35 MeV
14

C4+ was aceelerated with a pilot beam of 7Li2. After the 2nd stripper foil, 35 MeV 14C5+ was detected by

the gas ΔE-E detector. Fig. 2 shows the 14C5+ spectrum for the standard sample. The measurement
precision was approximately ± 5 %.
32

Si-AMS

We checked the beam transport for 32Si AMS by using the pure SiO2 sample. The terminal volatge wasselected at 9 MV, and the pilot beam of 16O2 was used to stablize the terminal voltage. 32Si8+ and 16O4+ hadsame mass energy product (ME/q2) of 40.5 MeV amu. After the 2nd stripper foil, 32Si8+ was changed to32

Si11+. The transmission of 28Si8+ with ME/q2 = 40.5 MeV amu was 24.6 % for the AMS system. Fig. 3

shows the spectrum for the pure SiO2 target as a blank sample. Isobaric interference of 32S11+ was strongly
appeared on the spectrum. Next step, the perfomance of 32Si AMS will be examied by the standard sample.
References[1] K. Sasa et al., Nucl. Instrum. Methods Phys. Res. B259 (2007) 41-46.
[2] P. Sharma et al., Nucl. Instrum. Methods Phys. Res. B52 (1990) 410-415.

5

1.3

Developments of ERCS hydrogen analysis

T. Komatsubara, K. Sasa, D. Sekiba, S. Ishii, Y. Yamato, K. Ebisu, T. Kawamata and M. Kurosawa
In order to improve precision and accuracy several developments have been performed for the Elastic
Recoil Coincidence Spectrometry (ERCS) hydrogen analysis.
For the calibration of hydrogen content Mylar
films are used as the reference material. However,long period of irradiation causes damage of the
Mylar films to reduce scattering yields. Hydrogen in
the films could be expelled by the atomic collisionsof the beam irradiation. In order to estimate thereduction of the yield the damage cross section σwere measured. The damage cross section σ can be
defined as

Y = Y0 e − σ φ

Fig.

1.

Damagecross

sectiondepending on a beam current at an

where φ denotes fluence which is a ratio between number

irradiation energy of 20 MeV.

of irradiated particles and area of the irradiation. Y and Y0
describe a scattering yield and its initial value.
Figure 1 shows measured results of damage crosssections by changing beam current. Mylar film of 2.5
micro m thick is irradiated by 20 MeV proton beam.
Measured data are rather scattered, however, theyremain in the range 0.4-0.9 Mb for the different beam
current. An average of the damage cross section isevaluated to be 0.66±0.06 Mb at 20 MeV.
Figure 2 shows energy dependence of the damage
cross section. Calculated values by Kinchin-Peasemodel[2] are shown by a solid line where the crossFig. 2. Damage cross section as a function

section is proportional to inverse of the irradiation

of

beam

energy.

Solidenergy.

calculated

valuesby

In the measurement of ERCS hydrogen analysis, depth

model[2].

line

shows

Kinchin-Peaseprofile is one of the advantages of this method. In orderto improve quality of the depth profile, systematicalmeasurements of the depth resolution were carried out.
For the target materials, thin foils of SiO2, Al, Cu, and W were irradiated. The measured results are shownin Fig. 3 where the bombarding energy of the proton beam was 20 MeV. In this figure, detector resolution
is subtracted. In Fig.3, a solid line shows Bohr value;

6

FWHM = 2 2 ln 2

1
4πε 0

4πz 2 e 4

Z
Na x
A

where z denotes atomic number of the projectile, A and Z are mass and atomic numbers for target, x is
thickness of the target film in (g/m2) and Na denotes Avogadro constant. The measured results are well
reproduced by the Bohr values except for the W.

Fig. 3. Straggling for SiO2, Al, Cu
and W. Bohr values are shown by
the solid line.
In order to reduce edge scattering as background of spectra, detector slits wereTable 1 New slit system for ERCS coincidence detectors.

modified. Single slit system has beenchangedtobedoubleslit

system.

Consequence of the modification, edge
scattering is reduced to be about 70%.
Geometry of the new slit system is shown in
Table 1. Detection solid angle is determined

Right-1
Right-2
Left-1
Left-2

Diameter(mm) Distance(mm) Solid
angle
(msr)
5.6
26.5
35.1
10
38
54.3
10
26.5
111.8
14
38
106.6

by the first slit in right detector to be 35.1
msr.
References[1] T. Komatsubara et al. Nucl. Instr. and Meth. B251 (2006) 237[2] P. Reichart et al. Nucl. Instr. and Meth. B197 (2002)134

7

2.
NUCLEAR PHYSICS

2.1

Production of radioactive nuclear beam ofidentification

8

Li and its in-flight

K. Y. Hara, A. Ozawa, Y. Hashizume, S. Igarashi, Y. Ito, T. Moriguchi, K. Ogawa, Y. Tagishi,
K. Yamaguchi, and Y. Yasuda
A radioactive nuclear beam of 8Li (half life t1/2=838 ms) was produced at UTTAC by using a transfer
reaction. A 40-MeV 7Li3+ beam from the tandem accelerator was irradiated on a CD2 target with athickness of about 1 mg/cm2.The intensity of 7Li3+ beam was ~100 nA. As shown in the inset of Fig.1, thetarget was located at downstream of an analyzer magnet. The 8Li3+ beam ejected at a forward angle by theD(7Li, 8Li)p reaction was transported to the beam line of F-course in the first experimental room. Theenergy of 8Li3+ beam is estimated at about 38 MeV by taking account of the kinematics of the D(7Li, 8Li)preaction and the energy loss in the CD2 target. In order to separate the secondary beam from the primarybeam, a Q-Q-D-Q-Q transport system which consists of a switching magnet and 2 doublet quadruple
magnets was used (see the inset of Fig.1), where Q and D stand for quadruple magnet and dipole magnet,
respectively.
Figure 1 shows an experimental setup at F-course for in-flight particle identification. A Q-D-Q magnetic
spectrograph at zero degree to the beam line was set with a magnetic rigidity (Bρ) for the 8Li3+ beam. The
beam was measured with 2 parallel-plate avalanche counters (PPAC’s) and a telescope of ΔE-E Si
solid-state detectors (SSD's). For the calibration of the detectors, the faint beams of 7Li3+ from theaccelerator at 34 and 40 MeV were also transported.

Fig.1: Schematic views of the experimental setup in F-course and the Q-Q-D-Q-Q transport system.
PPAC consists of three plates; cathode (X), anode, and cathode (Y) [1]. The beam was monitored by the9counting rates of the anodes signals and the two-dimensional positions derived from the charge-division
signals of the cathodes. The start and the stop signals for TOF measurements were obtained from theanodes of PPAC1 and PPAC2, respectively. The flight path between PPAC1 and PPAC2 is ~4 m. The full
width at half maximum in the TOF spectrum is 6 ns (Fig. 2 (a)). The ΔE-SSD with a thickness of 50 μm
and E-SSD with a thickness of 300 μm were used in the energy loss and total energy measurements,
respectively. These energy spectra are shown in Fig. 2(b) and 2(c). Peaks in the low-energy part show
pedestal; where the beam do not hit both SSD’s, while the coincidence events of PPAC1 and PPAC2 areused as the trigger signals for the data acquisition. The typical counting rates are 1 kcps at PPAC1 and 100
cps at PPAC2. In contrast, the counting rates of SSD’s are very low (~10 cps). The rate of PPAC1 isreasonable in comparison with one estimated from the cross section of the D(7Li, 8Li)p reaction. The
counting rates of PPAC2 and SSD’s could be improved with the optimization of beam transport.
The two-dimensional scatter plot of the energy loss in ΔE-SSD versus TOF is shown in Fig. 2(d). For
in-flight particle identification, the results of calculations for 7Li2+, 7Li3+, and 8Li3+ with the same Bρ arealso plotted as the triangle, square, and circle, respectively, in the figure, where we calculated the energy
loss in the detectors and the TOF by assuming the 38-MeV incident energy of the 8Li3+ beam at upstreamof PPAC1. The locus in Fig. 2(d) is in agreement with the estimation for 8Li3+ and is nearly free from thecontamination of the primary beam. In addition to the above Bρ-TOF-ΔE method, we confirm the particle
identification by using the Fig. 2(e) that shows the two-dimensional scatter plot of the energy loss in
ΔE-SSD versus the summed energy in its ΔE-E telescope. The calculations are presented in the Fig. 2(e) as
well as Fig. 2(d).
The present results show the present setup allows in-flight identification for radioactive nuclear beam.
Therefore it may be possible to measure, for example, total reaction cross section at the present energy.
counts

250

(a)

15

20

200
150
100
50
0

20

40

60

TOF (ns)
(d)
7

2+

Li

8

Li

7

Li

0

20

40

60

0

80 100 120 140 160 180 200

3+ΔE (MeV)

20
18
16
14
12
10
8
6
4
2
0

(b)

300

countsΔE (MeV)

1200
1000
800
600
400
200
0

countsThe particle identification is indispensable in these experiments. Further developments are required.

3+

80 100 120 140 160 180 200

20
18
16
14
12
10
8
6
4
2
0

0

5

10

140
120
100
80
60
40
20
0

(c)

0

ΔE (MeV)

10

20

30

40

E (MeV)
(e)

7

2+

Li

8

3+

Li

7

0

10

20

30

3+

Li

40

50

60

ΔE+E (MeV)

TOF (ns)Fig.2: (a) TOF spectrum between PPAC1 and PPAC2, (b) energy spectrum of ΔE-SSD, (c) energy
spectrum of E-SSD, (d)(e) two-dimensional scatter plots for particle identification (see text for details).
References[1] H. Kumagai et al., Nucl. Instr. and Meth. A 470 (2001) 562.

10

2.2

118 Sn(d,p) reaction in search for Coulomb stripping of deuteron. V

M.Iijima, Y.Aoki and A.Ozawa
Coulomb stripping of deuterons were proposed by Oppenheimer and Phillips in the 1930s [1]. To
elucidate its mechanism, we measured 118 Sn(d, p0,1,2 ) reactions at Ed = 3.2 ∼ 6.0 MeV [2]. The residual
nucleus 119 Sn has its first and second excited states at Ex = 23.9 keV and 89.5 keV. We tried to measure
only 118 Sn(d, p0 ) at the beginning of the experiment. Later it was found difficult at our detector resolution
to separate 118 Sn(d, p0 ) reaction from (d, p1 ) and (d, p2 ) reactions. Thus the deduced experimental crosssections are for the sum of the three reactions, which are denoted in Fig.1 as circles with errors in it.
dσ
Theoretical dΩ
for the reactions are calculated by DWBA and CDCC(d,p). As for the difference between

DWBA and CDCC(d,p), it is explained in terms of transition matrices. The matrix element for A(d,p)B
reaction [3] is given by:
(−)

(+)

T (d, p) = hχp ΦB |Vnp +VpA −UpB |ΨdA i(−)

where ΦB is the internal wave function for the residual nucleus, χp(1)

is the distorted wave under optical(+)
potential UpB , and ΨdA is the full wave function of the incident channel. In CDCC(d,p) calculations
¢
¡
(+)
(+)
VpA −UpB is neglected and ΨdA is replaced by the product of CDCC wave function ΨCDCC and internal

wave function ΦA .
(−)

(+)

T (CDCC(d, p)) = hχp ΦB |Vnp |ΨCDCC ΦA i
(+)

(+)

(+)

In DWBA ΨdA is replaced by χd ΦA , where χd(2)is the initial state distorted wave function under opticalpotential UdA .
(−)

(+)

T (DWBA) = hχp ΦB |Vnp |χd ΦA i

(3)

Finite range DWBA calculations [4] are performed for 118 Sn(d, p0 ), (d, p1 ) and (d, p2 ) reactions respec¡ dσ ¢¡ dσ ¢¡ dσ ¢
tively. We need to get the sum of the DWBA cross sections dΩ, dΩ
and dΩ
to fit the(d,p )(d,p )(d,p )
dσ
experimental dΩ
.

0

dσ
= S0
dΩ

µ

dσ
dΩ

¶

µ
+ S1

(d,p0 )

dσ
dΩ

¶

µ
+ S2

(d,p1 )

1

dσ
dΩ

2

¶
(4)
(d,p2 )

S0 , S1 and S2 are the spectroscopic factors for (d, p0 ), (d, p1 ) and (d, p2 ) reactions respectively. We set(S0 , S1 , S2 ) = (1.55, 0, 0) to examine the (d, p0 ) contribution. S0 is adjusted to the value to normalize
the DWBA cross sections at Ed = 6.0 MeV. Thus obtained DWBA cross sections are shown in lines ofFig.1. It is clear that the experimental cross sections are underestimated at Ed = 3.2 and 3.5 MeV. We alsoset (S0 , S1 , S2 ) = (0, 1.77, 0) and (0, 0, 5.8) to check (d, p1 ) and (d, p2 ) contributions respectively. The
values S1 = 1.77 and S2 = 5.8 are chosen to normalize DWBA cross sections to those of experiments at
Ed = 6.0 MeV. In both cases there are underestimations at Ed = 3.2 and 3.5 MeV. Thus it is clear from (4)that it would be difficult to reproduce the experimental cross sections at Ed = 3.2 and 3.5 MeV by DWBA
calculations.
dσ
We performed CDCC(d,p) calculations at Ed = 6.0 MeV and obtained dΩwith and without the Coulomb
dσbreak-up (CBU) contributions. We take (S0 , S1 , S2 ) = (1.0, 0, 0) in (4) and compare dΩwith the DWBA
dσcalculation (Fig.2). When we get the values of dΩat θCM = 130◦ , the ratios of CDCC(d,p) cross sections

11

to that of DWBA are 0.99 without CBU and 0.87 with CBU. These CDCC(d,p) calculations still requires
improvements of parameters and we are now working on it.

References[1] J. R. Oppenheimer and M. Phillips, Phys. Rev. 48, 500(1935).
[2] M.Iijima, T.Ishikawa, D.Inomata and Y.Aoki, UTTAC Annual Report 76, 12(2007)[3] M.Iijima, Y.Aoki, A.Ozawa and N.Okumura, Nucl. Phys. A 793, 79(2007).
[4] M. Igarashi, Computer code TWOFNR, private communication. Full manual/source list can be downloaded from http://www.tac.tsukuba.ac.jp/˜yaoki.
1

Ed = 6.0 MeV

dσ/dΩ (mb/sr)

0.1

5.0 MeV

4.0 MeV

0.01

3.5 MeV
3.2 MeV

0.001

1e-04

60

70

80

90

100
110
θCM (deg.)

120

130

140

150

Fig. 1. Experimental and calculated cross sections

0.45
118

CDCC
without CBU

Sn(d,p0)
Ed = 6.0 MeV

0.4

dσ/dΩ (mb/sr)

0.35
0.3
0.25
DWBA
0.2
CDCC
with CBU

0.15
0.1
0.05

0

20

40

60

80
100
θCM (deg.)

120

140

160

180

Fig. 2. Comparison of DWBA and CDCC(d,p) cross sections

12

2.3

Measurement of the time response in Hybrid Photo Detector II

T. Moriguchi, Y. Hashizume, T. Hoya, K. Ogawa, Y. Yasuda, K. Hara and A. Ozawa
The Isochronous Storage Ring at RIKEN RI Beam Factory (RIBF) is designed to measure mass of
unstable nuclei. The purpose of the research is nuclear synthesize in neutron rich side with r-process,where it is predicted that Uranium was synthesized. However, the prediction is not proved due to difficultyof production of such neutron rich nuclei. RIBF will be able to produce many unstable nuclei that we had
never reached in the past. The precise mass of these unstable nuclei is expected to understand the path of
the r-process.
We determine the mass by measuring the cyclotron frequency which can be measured by TOF (Time Of
Flight) of the nuclei inside the Storage Ring. In order to determine mass precisely (δm/m ~ 10-6), TOF
detectors need to have high timing resolution (< 100ps).
We started to develop a Hybrid Photo Detector (HPD) as TOF detectors with high timing resolution. In
2006, we measured the timing resolution of HPD (HAMAMATSU R7110U-07) at University of Tsukuba
Tandem Accelerator Complex (UTTAC) [1]. The timing resolution of the previous HPD is worse than thatof the Photo Multiplier Tube (PMT, HAMAMATSU R4998). In 2007, we tested a high speed HPD(HS-HPD, HAMAMATSU R10467U-06) whose Avalanche Diode was developed newly to be very low
capacitance. The photocathode of HS-HPD was fabricated on a plano-concave faceplate of φ8 mm toadjust the transit time of electrons to be equal over the photocathode. HS-HPD as shown in Figure 1 has
fast time response and small transit time spread (see Table 1).
Table 1. Specifications of HPD [2][3].
PhotocathodeMaterial
Effective Area [mm]Max High Voltage [kV]Avalanche Diode
Capacitance [pF]
Max Bias Voltage [V]Electron Bombaｒded Gain
Avalanche Gain
Rise Time [ns]Fall Time [ns]Transit Time Spread [ps]HPD
Multialkali
φ8
-8.5
140
+155
1200
50
1.1
14.8
277

High Speed HPD
Bialkali
φ8
-8.5
3.4
+405
1500
90
0.4
0.4
47

The experiment was performed at 1F course with Q-D-Q magnet in the 12UD tandem accelerator of
UTTAC using 60MeV carbon beam with the same setup in previous [1]. Figure 2 shows a schematic viewof the experimental setup. We measured the timing resolution of two different types of HS-HPDs, Positive
HS-HPD (P-HPD) and Negative HS-HPD (N-HPD) in Fig. 2. Both HS-HPDs have almost same
specifications except the difference of polarity of output signals. We also tested PMT2 in order to compare
the time response with the HPD. In the experiment, we changed only the detectors, keeping PMT1 with a13

plastic scintillator. The detectors were located in a box to shield the light. The trigger signal was made by
the coincidence with two signals from both side detectors.
Figure 3 shows typical pulse shapes from P-HPD and PMT1. The pulse from N-HPD was also the sameas that from P-HPD except for the polarity. Rise time of HS-HPD was 4ns, this value was the same as thatof PMT. However, the pulse height of HS-HPD was less than PMT since the gain of HS-HPD is smaller
than PMT by two orders of magnitude. During the measurement of

the timing resolution, the pulse

height of HS-HPD was amplified by using amplifiers (ORTEC AN302/N). Table 2 shows the results of thetiming resolution of HS-HPD and PMT2. AMP in Table 2 means the number of using amplifiers.
According to Table 2, larger pulse height becomes better timing resolution. HS-HPD achieved the bettertiming resolution than that of the previous HPD [1]. However, the timing resolution of HS-HPD wasworse than that of PMT2.
In summary, we measured the timing resolution of HS-HPD with 60MeV carbon beam in UTTAC.
Comparing the results of HS-HPD with those of the previous HPD, the rise time was faster and the timing
resolution was better. However, the timing resolution of HS-HPD was worse than that of PMT.
HS-HPD (R10467U-06)
P-HPD:Postive Output

Light shield box
N-HPD

P-HPD

Al
(Thickness:12μm)

ChangeQ2

D

N-HPD:Negative Output
PMT (R4998)
PMT1:Trigger (Fix)
PMT2:For comparison

PMT2

Au
(Thickness:2μm)

Mylar(Thickness:4μm)

PMT1

Fig. 1. The high speed HPD

35deg

Q1

Scatter
Chamber

Plastic Scintillator(50 x 50 x 0.6 mm^3)

UTTAC 1F-Course(HAMAMATSU R10467U-06).

C (60MeV)
Beam

Fig. 2. Schematic view of the experimental setup.

Table 2. The results of the timing resolution [ns].
AMP
P-HPD
N-HPD
PMT2

Fig. 3. Typical pulse shapes for P-HPD and

0
249±1

2
590±3
603±3
-

3
453±4
434±3
-

PMT1, respectively.
References[1] T. Moriguchi et al., UTTAC Annual Report 2006, UTTAC-76 (2007) 14.
[2] Hamamatsu Photonics K.K., Electron Tube Division, technical note of R7110U series (2001).
[3] Hamamatsu Photonics K.K., Electron Tube Division, technical note of R10467 series (2006).

14

4
389±3
390±2
-

2.4

Study of nuclear synthesis of 26Al by gamma ray spectroscopy

T. Komatsubara, K. Ebisu, T. Kawamata, A. Ozawa, K. Hara, T. Moriguchi, Y. Hashizume, T. Shizuma*, T.
Hayakawa* and S. Kubono#* JAEA#Tokyo University, CNS
Since observation of 1.809-MeV gamma rays by satellite gamma ray telescope has been reported[1], theastrophysical study of 26Al is very important for nuclear synthesis. The gamma ray is observed emittingfrom center of our galaxy. The Dopplar shift of the observed gamma ray energy is consistent to therotation of the galaxy. The ground state of the 26Al is 5+ and its half life is 7.2 ×104 year. The state decays
into the 2+ state of 26Mg and emits the gamma ray from the 2+ to 0+. If one considers that the half life isshort compared to the period of the life of the galaxy, it can be understood that the nuclear synthesis
should be active at present. Diehl estimated that the mass of the 26Al is 2.8 solar in our galaxy and rate ofsuper-nova is 1.9 ± 1.1 /100 years[1]. The origin of the 26Al is still unknown. Massive star, Walf Rayet star,
nova or super-nova are candidates of the production location.
The nucleus 26Al can be created by 25Mg(p,γ) reaction. However there is bypass reaction sequence
25

Al(p,γ)26Si(β,ν)26mAl(β,ν) which emits no gamma ray of 1.809 MeV. The bypass sequence is considered

to be proceeded via 3+ resonance state in 26Si which is not established yet. The purpose of this study is toinvestigate nuclear levels in 26Si for the estimation of production rate of 26Al.
By using reaction analysis, there are several researches to investigate nuclear levels in 26Si. Badayan
reported observation of levels above proton threshold by (p,t) reaction[2]. Caggiano used (3He,6He)
reaction to populate the levels[3]. Parpottas investigated by (3He,n) reaction measuring emitting neutron
spectra[4].

Recently, Seweryniak studied excited states in 26Si by using GAMMA SPHERE[5] observing

1+ state at 5677-keV.
In order to investigate level structure in 26Si, in-beam gamma ray spectroscopy was performed at UTTAC
by using Ge detectors. The excited states of the 26Si were populated by the nuclear reaction24

Mg(3He,n)26Si. The 3He beam of 10 MeV was irradiated on a natural Mg target. Gamma-gamma

coincidence measurements were performed by using three Ge detectors. Relative efficiencies of the Ge
detectors are 140%, 70% and 50%. Two neutron detectors were also employed for the test experiment of
neutron-gamma coincidence measurements.
As a result of the analysis of the coincidence measurements, level scheme of 26Si is shown in Fig. 1. A
new level is found at 5886-keV which is above proton threshold. The newly found level is fed into the first2+ and the second 2+ states by emitting 3100- and 4089-keV gamma rays, respectively. If one compares thenuclear structure with mirror nucleus 26Mg[6], spin of this level can be assigned other than 3+ because
strong feeding has been observed from the third 3+ to the second 3+ in the 26Mg.

15

References[1] R. Diehl, H. Halloin, K. Kretschmer, G.G. Lichti, V. Schönfelder, A.W. Strong, A. Kienlin, W. Wang, P.
Jean, J. Knödlseder, J.P. Roques, G. Weidenspointner, S. Schanne, D.H. Hartmann, C. Winkler, C.
Wunderer, Nature 439 (2006) 45[2] D.W. Bardayan, J.C. Blackmon, A.E. Champagne, A.K. Dummer, T. Davinson, U. Greife, D. Hill, C.
Iliadis, B.A. Johnson, R.L. Kozub, C.S. Lee, M.S. Smith, P.J. Woods, Phys. Rev. C 65 (2002) 032801(R)[3] J.A. Caggiano, W.B. Smith, R. Lewis, P.D. Parker, D.W. Visser, J.P. Greene, K.E. Rehm, D.W.
Bardayan, A.E. Champagne, Phys. Rev. C 65 (2002) 055801[4] Y. Parpottas, S. M. Grimes, S. Al-Quraishi, C.R. Brune, T.N. Massey, J.E. Oldendick, A. Salas, T.
Wheeler, Phys. Rev. C 70 (2004) 065805[5] D. Seweryniak, P.J. Woods, M.P. Carpenter, T. Davinson, R.V.F. Janssens, D.G. Jenkins, T. Lauritsen,
C.J. Lister, J. Shergur, S. Sinha, A. Woehr, Phys. Rev. C 75 (2007) 062801(R)[6] P.M. Endt, Nucl. Phys. A 633 (1998) 1

Fig.1 Level structure of 26Si.

16

Nuclear structure of supernova neutrino-process isotope 138La

2.5

T. Hayakawa 1,2, T. Komatsubara, T.Shizuma 1
Rare odd-odd isotopes of 138La and 180Ta are grouped to p-nuclei [1]. As the origin of the two isotopes, asupernova neutrino-induced reaction nucleosynthesis (ν-process) was suggested [2]. The ν-process is ofimportance for studying neutrino spectra from the supernovae, and for discussing neutrino oscillation [3,4].
Among many heavy elements, only two isotopes of 138La and 180Ta are considered to be synthesized
primarily by the ν-process but 180Ta is also considered to be produced by the s-process. The solar
abundance of 138La was quantitatively explained by the ν-process in theoretical calculations [3,5].
Recently, Hayakawa et al. proposed 138La as a nuclear cosmochronometer for measuring the time elapsed
from a neutrino-window driven supernova explosion [6]. Therefore, 138La is a key isotope forunderstanding the ν-process. Information of low spin excited states in 138La are of importance fortheoretical calculation of neutrino-induced reaction rate (see Fig. 1) but the details of the low spin states
have not been studied well experimentally. Here we study the nuclear structure of 138La by using in-beamgamma-ray spectroscopy technique with a (p, n) reaction.
Excited states in 138La were populated by a 138Ba(p, n)138La reaction. The proton beam of an energy of
10 MeV was provided by the tandem accelerator at University of Tsukuba. Compressed BaCO3 power wasused as a target with a thickness of about 70 mg/cm2. 138Ba was enriched to about 99%. In the present
experiment, 138La was dominantly populated since neutron evaporation channel is dominant in this

Ce

140

β- decayν process
Ba

Ba

136

γ-rays from the excited states were detected

Neutral current reaction

La

138

EC decay135

reaction and we used the enriched target. The

Ce

138

137

Ba

with three HPGe detectors. The evapolated
neutrons were detected by a liquid scintillator.

La

139

The efficiencies of the HPGe detectors were

Charged current about 50-70% relative to a 3 in. × 3 in. NaI
reaction

detector. Typical energy resolution was 2.6 keV

Ba

138

at 1.3 MeV. We obtained γ−γ and γ-ncoincidence data, leading information of

Fig.1. Nuclear synthesis flow aroundnuclear structure of 138La.

138

La

References[1] T. Hayakawa, et al. to be published in Astrophys. J (2008).
[2] S.E Woosley, et al., Astrophys. J. 356, 272 (1990).
[3] A. Heger, et al., Phys. Lett. B 606, 258 (2005).
[4] T. Yoshida, et al., Phys. Rev. Lett., 96, 091101 (2006).
[5] A. Byelikov, et al., Phys. Rev. Lett. 98, 082501 (2007).
[6] T. Hayakawa, et al., to be published in Phys. Rev. C (2008).
1

Japan Atomic Energy Agency

2

National Astronomical Observatory

17

3.
MATERIALS AND CLUSTER SCIENCE

3.1

Synthesis of elongated and oriented gold nanorods in silica byirradiation of swift heavy ion

K. Awazu1, X. Wang1, M. Fujimaki1, J.Tominaga1, H.Aiba2, Y.Ohki2, T. Komatsubara

It has been reported that elongated Au nanoparticles oriented parallel to each other can be synthesized in
SiO2 by ion irradiation.[1] Our aim was to elucidate the mechanism for this elongation. We prepared Au
nanoparticles with various diameters from 10 to 80 nm in a SiO2 matrix. Figure 1 shows a cross-sectionaltransmission electron micrograph of SiO2-embedded Au nanoparticles after irradiation by 110-MeV Br10+
at a fluence of 1 × 1014 cm–2. Note that elongation of Au nanoparticles with a small radius was larger thanthat of Au nanoparticles with a large radius. These experimental results are discussed in the framework of
a thermal spike model of Au nanorods with a radius of 5 or 10 nm embedded in SiO2. As shown in Figure
2 (a), the lattice temperature [2] exceeds the melting temperatures of both SiO2 and Au for 100 ns after one
110-MeV Br10+ ion has passed through the middle of an Au nanorod of radius of 5 nm. In contrast, withthe 10-nm Au rod shown in Figure 2 (b), neither the rod nor the SiO2 is melted by 110-MeV Br10+. We
conclude that dependence of the elongation of the Au nanoparticles on particle size can be explained interms of the thermal spike model.

50nm

Fig.1.Cross-sectional TEM image of Au nanoparticles ofvarious sizes in SiO2 irradiated with 110-MeV Br10+.

19

Lattice temperature (K)

3000

2000

(b)

r = 1 nmr = 3.5 nm
r = 6.5 nm
r = 10 nm
r = 20 nm
r = 100 nm

1500
Tm of SiO2 =1972K

Tm of Au =1337K

1000

10-16

10-14

2000

Lattice temperature (K)(a)

Time (s)

10-12

10-10

r = 1 nmr = 3.5 nm
r = 6.5 nm
r = 10 nm
r = 20 nm
r = 100 nm

Tm of SiO2=1972K

Tm of Au=1337K

1000

500

10-16

10-14

10-12

10-10

Time (s)Fig.2. The simulated evolution of the electronic temperature versus time at various distances (1,3.5, 6.5, 10, 20, and 100 nm) from the ion path when a 110 MeV Br10+ ion penetrates the center ofa gold particle embedded in SiO2. The radii of the Au nanoparticles are 5 nm (a) and 10 nm (b).
The beam electronic energy loss rate is assumed to be Se = 9.203 keV/nm. The initial temperatureof the sample is 300 K.

References[1] S. Roorda et al., Adv. Master. 16 (2004) 235.
[2] M. Toulemonde et al., Nucl. Instr. and Meth. B166-167 (2000) 903.

20

3.2

Characterization of Er-doped GaN by heavy ion RBS

T. Waki, Y. Kaku, S. Tomita, A. Uedono, Shaoqiang Chen, K. Akimoto, and H. Kudo
Rutherford backscattering spectroscopy (RBS) using fast heavy ions can provide high mass-resolution
analysis of heavy elements embedded in the surface layers of materials.

Actually, this has been applied

to the characterization of Er-doped GaN with interest on the crystal quality and the lattice site of Er atoms
in GaN. Such structural information is of essential importance in electronic device applications.
The GaN samples were 0.8-μm-thick Er-doped GaN grown on (0001) sapphire substrates by gas-source
MBE using NH3 as the nitrogen source [1]. The RBS measurements were carried out using 30-MeV O5+
obtained from a 12MV tandem accelerator, and also using 1.6-MeV He+ for comparison of the mass
resolution. The three-axis goniometer used for channeling incidence conditions was remote-controlled
under the pressure of ~3×10-6 Pa.
Figure 1 compares the nonchanneling RBS spectra for the two beams, which were obtained for the same
sample. The spectra for Ga and the doped Er can be separated for 30-MeV O5+, while they are seriously
overlapped for 1.6-MeV He+, demonstrating the high mass-resolution of heavy ion RBS.
30MeV O5+ RBS#1205 （4atm%）

Random071221 GaN:Er 1.6MeV He+ RBS

5000
4500

600

GaN: 4%Er

4000

Yield

3500
3000

400

2500
2000

Ga

1500

200

Ｇａ

1000

Ｅｒ

500

Er

0

0
0

200

400

600

800

1000

100

Pulse height

Channel number

Fig.1

200

300

400

500

600

700

800

Channel number

Comparison of the RBS spectra for 30-MeV O5+ and 1.6-MeV He+.

Figure 2 shows the results for RBS-channeling measurements using 30-MeV O5+. In Fig. 2(a), theminimum yield which is a measure of the crystal quality is as large as ~0.75 even for Er doping of 1at%.
This is contrast to the observed minimum yield of ～0.01 for nondoped GaN. The tilt-angle dependenceof the RBS yield from the substrate Ga and the doped Er is shown in Fig. 2(b). A comparison of theangular dips for Er and Ga indicates that, on the average, ~75% Er atoms occupy substitutional sites. The
rest 25% should correspond to small displacement from the substitutional sites. Determination of the siteof 25% Er requires further information about the behavior of Er in an imperfect GaN lattice.
Furthermore, we have found an increase of Er concentration near the GaN/substrate interface. The stressdue to the lattice mismatch near the interface might be relaxed by the concentrated Er which provides a21

bond-length of Er-N which is different from Ga-N.

Thus, Er is likely to accumulate near the interface

and would result in the introduction of vacancy-type defects which have been observed recently by using amonoenergetic positron beam [2].

1.2

1.8

(a)

(b)

o

Ga

1.4

Ga
Er

1.1

Normalized yield

Relative backscattering yield

1.6

5+

30MeV O , 147
nonchanneling<0001>

1.2
1.0
0.8
0.6

1.0
0.9
0.8

0.4

0.7

Er

0.2
0.0
4

8

12

16

20

24

0.6
-1.5

Energy (MeV)

Fig. 2

-1.0

-0.5

0.0

0.5

1.0

Tilt angle θ (deg)(a) RBS-channeling spectra of 1at%-Er doped GaN, epitaxially grown on sapphire.

(b) Tilt-angle dependence of the RBS yield near <0001>.

References[1] S. Morishima, T. Maruyama, K. Akimoto, J. Crystal Growth 209, 378 (2000).
[2] A. Uedono et al., accepted for publication.

22

1.5

3.3

Dependence of the vicinage effect on interatomic spacing of carbon
clusters

M. Murakami, S. Tomita, K. Shiba, S. Ishii, K. Sasa and H. Kudo
When fast molecular ions are incident on a solid, the energy loss per atom is different from that ofsingle atomic ions. This is known as “vicinage effect”. In the case of 0.5MeV/atom Cn+(n=1~4) clusters,
the energy loss for cluster ions is lower than that of atomic ion. The results are quantitatively understoodby considering the interference of electrons scattered by individual atoms. The vicinage effect should
become weaker with increasing the foil thickness because the interatomic distance within the injectedcluster ion increases as the ion penetrates deeper. In this work, we investigate the dependence of thevicinage effect in the energy loss of carbon clusters on the foil thickness.
Schematic experimental setup is shown in Fig.1. A thin carbon foil was mounted on one side of the
double frame which underwent metronomic motion together with other empty frame. The projectiles
transmitted either through the foil or the empty
SSD

frame hit a thin Au target placed at justAperture

downstream of the device. The energy of thescattered carbon atoms by the target was100°

measured with particle detector (SSD) at a

Ion beam

backward angle of 100˚. The energy of Cn+ was

0.5 MeV/atom
Cn+ (n=1~4)

Aperture φ1.0

0.5 MeV/atom. The thicknesses of the carbon

Au(~3Å) on HOPG

Targetfoil were 3.3 and 14.2 μg/cm2. Atomic

Fig.1. Schematic view of the experimental setup in the
scattering chamber

distances inside the foil were estimated fromthe coulomb explosion of C2+ as 1.7 and 5.3 Å
for 3.3 and 14.2 μg/cm2, respectively.

ΔE(Cn+)/nΔE(C1)

The ratios of the observed energy loss to
1.01

that of atomic ions are shown in Fig.2. As seen

1.00

in Fig. 2, the energy-loss ratios for C4+ are

0.99

0.953 and 0.972 for 3.3 and 14.2 μg/cm2,

0.98

respectively. If the vicinage effect disappears at

0.97

a depth of 3.3 μg/cm2, the ratio of the observed

0.96
0.95

energy loss for 14.2 μg/cm2 should be

Exmental value
14.2μg/cm2
3.3μg/cm2

3.3×0.953+(14.2-3.3)×1]/14.2=0.989. However,
the observed value is 0.972. From this

0.94
1

2

3

4

difference, we can conclude that the vicinage

Cluster size n

Fig.2. The energy loss per atom of 0.5MeV/atom Cn+

23

effect surely remains at a depth of 3.3μg/cm2.

3.4

Point defects in Er-doped GaN probed by means of positronannihilation

H. Nakamori, A. Uedono, C. Shaoqiang, S. Jongwon, K. Ito, N. Honda, S. Tomita, K. Akimoto, H. Kudo,
and S. Ishibashi 1
Optical properties of Er-doped GaN have been extensively studied due to their potential in device
applications. The emission efficiency of Er-doped GaN, however, is very low and it was reported that
intensities of photo luminescence (PL) are strongly influenced by the presence of a special distribution ofpoint defects and dislocations [1]. Hence, a fundamental understanding of the behavior of point defects isvery important to effectively utilize optical devices based on RE-doped GaN. In the present study, weprobed vacancy-type defects in Er-doped GaN using positron annihilation spectroscopy (PAS) to
investigate the relationship between such defects and the emission intensity.
The samples were 0.8-μm-thick Er-doped GaN grown on (0001) sapphire substrates by gas-source
MBE using NH3 as the nitrogen source. Details of the growth method are given elsewhere [2]. Before
growth, the substrate was nitridated under an NH3 pressure of 5×10-3 Pa for 10 min at 940oC. The substratetemperature was kept at 700oC during the growth. 3.5-μm-thick undoped GaN was also fabricated using
growth conditions similar to those described above. PL measurements were done using an Argon laser(488 nm) at 77K. The structural properties of the films were evaluated by x-ray diffraction (XRD) using
Cu Kα1 and Kα2 radiation. The Er concentrations [Er] and their depth distributions were measured by
Rutherford back scattering (RBS) using 30-MeV O5+ obtained from a 12 MV tandem-accelerator. With amonoenergetic positron beam, the Doppler broadening spectra of the annihilation radiation were measured
as a function of the incident positron energy for samples with an Er concentration between 0.3 at.% and
6.0 at.%. The resultant changes in the spectra are characterized by the S parameter, defined as the numberof annihilation events over the energy range of 511 keV ± ΔEγ (where ΔEγ = 0.76 keV) around the centerof the peak and by the W parameter, which is calculated from the tail of the peak, in the range of 3.4 keV ≤⏐ΔEγ⏐ ≤ 6.8 keV. In general, the characteristic value of S (W) for the annihilation of positrons trapped byvacancy-type defects is larger (smaller) than that for positrons annihilated from the free-state.
In Fig. 1, the S values as a function of incident positron energy E for each sample were shown. The S
value increased with increasing Er-concentration ([Er] ≤ 3.3 at.%), suggesting the introduction ofvacancy-type defects due to Er incorporation. For Er-doped GaN with [Er] = 6.0 at.%, however, the S
value was smaller than that for the sample with [Er] = 3.3 at.%. This sample was observed degradation of
the crystallinity from XRD measurements. Therefore, it was considered that a positron could detectvacancies related to precipitates or metastable phases in the amorphous sample. The Er depth distributions
were shown in Fig. 2 and agreed well with that of vacancy-type defects, suggesting Er was accumulated
near the GaN/substrate interface where vacancy-type defects were introduced.

1

Research Institute for Computational Sciences, National Institute of Advanced Industrial Science and Technology, Tsukuba,
Ibaraki, 305-8568, Japan24

Mean implantation depth of positrons (μm)
00.1
0.3 0.5 0.7 1.0
0.50[Er] (at.%)S parameter

0.48
0.47

0.6
1.5
3.3
6.0

RBS yield (arb.)

0.49

0.46
0.45
0.44

Undoped

0.43

Defect-free (HVPE)

0.42
0

5

Fig. 1S as a function of incident positron

10
15
20
25
Positron energy (keV)

150

100

3.3 at.%50

1.5 at.%0.6 at.%30

022Fig. 221

20

19 18 17
Energy (MeV)16

15

RBS random spectra corresponding toenergy E for Er-doped GaN with [Er] =the depth distributions of Er in GaN with Er

0.3-6.0 at.%. The result for undoped GaN

concentrations of 0.6, 1.5, and 3.3 at.%.

is also shown.
We have also obtained a clear correlation between the point defects and the intensity of the intra-4f
transitions of Er. By the analysis of detail using S-W relationship and first-principles calculation [3, 4], it
was found that the major defect species detected by positron was identified as a Ga-vacancy (VGa) for the
undoped and Er-doped GaN with [Er] = 0.3-1.5 at.% and its concentration increased with increasing Er
concentration; the VGa concentration reached 3×1018 cm−3 at [Er] = 1.5 at.%. For the sample with [Er] = 3.3
at.%, the maximum integrated intensity of PL was observed, while the introduction of additional vacancies
such as divacancies started at this doping concentration.
In conclusion, we can suggest that defect engineering to control the defect species and theirconcentrations while preserving a highly crystalline GaN matrix is one key to increasing the emission rateof the intra-4f shell transitions from a RE metal.
References[1] A. Ishizumi, J. Sawahata, K. Akimoto, Y. Kanemitsu, Appl. Phys. Lett. 89, 191908 (2006).
[2] S. Morishima, T. Maruyama, K. Akimoto, J. Crystal Growth 209, 378 (2000).
[3] A. Uedono, K. Ito, H. Nakamori, K. Mori, Y. Nakano, T. Kachi, S. Ishibashi, T. Ohdaira, and R.
Suzuki, J. Appl. Phys. 102, 084505 (2007).
[4] S. Ishibashi, Materials Science Forum 445-446, 401 (2004).

25

3.5

Rutherford backscattering spectroscopy on Pt-adsorbed HOPG surface

D. Sekiba, T. Kondo, J.P. Oh, S. Ishii, H. Kudo, and J. Nakamura
Recently the Pt cluster evaporated on the highly oriented pyrolytic graphite (HOPG) has
attracted much attention as a model system of an electrode in low-temperature fuel cells. It has been
known that the catalytic activity of the Pt cluster on HOPG strongly depends on the structure in atomic
scale, which changes by catalytic treatment: evaporation condition, temperature and atmosphere during thecatalytic reactions. In particular, the catalytic activity of Pt cluster after increasing the temperature of the
HOPG substrate has been controversial. We have made experiments of temperature program desorption(TPD) spectroscopy of CO on Pt/HOPG. It has been found that the Pt cluster after one cycle of TPD
measurement no longer has the catalytic activity to adsorb the CO molecule again. This indicates that thesystem of Pt/HOPG was drastically changed due to the increase of temperature. A similar change of thePt/HOPG system were reported in terms of the electronic and morphologic structures by means of X-ray
photoemission spectroscopy (XPS). A.R. Howells et al. reported the binding energy shift of the Pt4f stateat ~ - 71 eV from Fermi level toward the lower binding energy with increasing the substrate temperature
up to 500 K, meanwhile the intensity of the Pt4f photoelectrons decreased continuously with increasing
the temperature. They observed also the change of the surface morphology due to the heating treatment by
scanning tunneling microscope (STM). The Pt island, which has dendritic structure, disappeared and only
unclear protrusions were observed.
There are some possibilities to interpret the catalytic activity loss of the Pt cluster after theheating treatment. One is that the electronic structure of Pt is changed due to the chemical bonds with thesurrounding carbon atoms, etc., and another extreme possibility is that the Pt atom desorbed from the
HOPG surface. Both cases do not conflict with the results of the XPS measurements. In other words, the
XPS measurements following the change of the photoelectron intensity cannot distinguish whether the Pt
atoms exist in subsurface region of HOPS or the Pt atoms are really removed from the system. To
elucidate this problem, we made Rutherford backscattering spectroscopy (RBS) measurements, which canestimate the absolute amount of the Pt atoms in the subsurface region as well as on the surface.
We mainly prepared four samples of Pt/HOPG: clean HOPG, 30 min. Pt-evaporated HOPG, 30
min. Pt-evaporated HOPG with a subsequent annealing up to 700 K, and finally 40 min. Pt-evaporated
HOPG. The RBS measurements were done at the beam line C in Tandetron accelerator. The 1.6 MeV He
ion (~ 2.5 nA) was used, and the backscattered ions were detected by a solid state detector (SSD) at theangle of 153 degree with respect to the beam incident direction. The collected charge of He ion was set at
5 x 10-7 C on target for a spectrum.
Figure 1 shows the RBS spectra taken on the four samples. We can see the steep edge at ~ 190channel indicating the HOPG substrate and the position of this edge is common among all the samples. No
impurity heavier than carbon was detected on the clean HOPG sample. On the Pt-evaporated samples wecan see distinct peak at ~ 725 channel indicating the existence of Pt atoms. The estimated coverages of Pt
on the 30min Pt-evaporated, 30 min. Pt-evaporated and annealed and 40 min. Pt-evaporated HOPG are

26

0.08 ML (mono-layer), 0.17 ML and 0.29 ML, respectively. It is noteworthy that an intense peakcorresponding to Pt was observed also on the sample annealed up to 700 K, so that the heating treatment
does not remove the Pt atoms from the substrate. This means that the loss of the catalytic activity of Pt due
to the heating treatment is caused by the change of chemical state of Pt, for example, the migration into
the subsurface region. Another indication by RBS results is fluctuation of the Pt evaporation rate during
the sample preparation. The Pt coverage determined by RBS is not exactly proportional to the evaporation
duration. The improvement of evaporation method will enable us to make more precise experiments on
this system.

Figure 1: RBS spectra taken on the clean HOPG, 30 min. Pt-evaporated HOPG, 30 min. Pt-evaporated
HOPG with a subsequent annealing up to 700 K, and finally 40 min. Pt-evaporated HOPG. The insets (a)and (b) compare the positions of edge and peak corresponding to the HOPG substrate and Pt, respectively.
The edge position of HOPG is identical on both samples, while the Pt peak position is slightly different
indicating that the change of the environment surrounding the Pt atoms, though the difference is still
within the margin of error in the experiments.
References[1] G. Zhang, D. Yang, E. Sacher, J. Phys. Chem. C 2007, 111, 565 – 570.
[2] A.R. Howells, L. Hung, G.S. Chottiner, D.A. Scherson, Solid State Ionics, 2002, 150, 53 – 62.

27

3.6

Mössbauer study of sub-micron sized Fe3 O4 particles and NH3 nitrized particles

M. Minagawa, H. Yanagihara, E. Kita and M. Kishimoto1
Recently iron nitrides attract much attention again as new magnetic materials because of their finemagnetic properties and low environmental loads[1]. However iron nitride compounds are categorized
as interstitial alloys, we have hardly ever obtained bulk samples so we have gained little information
about their essential physical properties. Therefore, we have synthesized iron nitride particles that havesub-micron diameter and determined their phases with X-ray diffraction (XRD) study and the Mössbauer
spectroscopy.
Fe3 O4 particles with spherical shape and 130 nm in diameter were used as a starting material. An
XRD pattern for the starting material is shown in Fig. 1(a). The oxide powder was reduced in H2 flow at
400 ◦ C for 2.5 hour and we obtained grayish powder (Fig.1(b)). After reduction, the powder was nitrided
in NH3 flow at 230 ◦ C for 24 hour (Fig.1(c)). From the XRD pattern, the particles consist mostly of γ’Fe4 N phase and small amount of ε-Fe3 N phase was detected. In order to increase the portion of γ’ phase,a successive nitriding technique was developed. The nitrided particles were H2 reduced for shorter period
and was followed by NH3 nitriding. The procedure and corresponding XRD were summarized in Table I.





&
$%
"#

α



γ

Intensity (arb.units)





(b)
(c)










ε

 

(a)



()



'&

!
)
)



γ

*










(d)
(e)












2θ ( degree )Fig. 1. Powder XRD patterns of the samples in nitridation processes

sample
(a)
(b)
(c)
(d)
(e)

nitridingtemp

nitridingtime

230 ◦ C
↑
↑

24 h
↑
↑

reducing reducing re-nitriding
temp
time
temp
starting material
as reduced at 400◦ C
230 ◦ C↑

1.0 h
1.75 h205 ◦ Cre-nitriding
time

18 h

XRD
patternFig.1(a)Fig.1(b)Fig.1(c)Fig.1(d)Fig.1(e)Table 1. Reducing and nitriding conditions for the successive nitriding techniqueAt the stage of sample(c), the ε-Fe3 N phase concentrated at the surface region and the annealing in
1 Hitachi Maxell, Ltd.

28

H2 flow pulled out nitrogen atoms forming NH3 . Thus the surface became α-Fe. The most satisfactory
condition was obtained with annealing in H2 flow for 1.75 hour followed by nitriding again at 205 ◦ C in
NH3 flow for 18 hour. An XRD pattern for the stage is shown in Fig.1(e) and it supports that the particles
were mostly in a γ’-Fe4 N single phase. From those steps of samples, we picked up the samples (a), (b)and (e), and Mössbauer studies were carried out.
"$# %('

Intensity (arb.units)

Intensity (arb.units)

3$4 55
5(4 78
5(4 79
5(4 7:(a)
R.T.

5(4 76
;.<$=

;(>

;?

@

?

>

Intensity (arb.units)    






!

%(# )+%(# )&%(# )'%(# )%(b)
R.T.

%(# **

,0





Velocity (mm/s)

,(1

2

1

0

-$/

Velocity (mm/sec)     %(# )*,.-$/(c) Sample(e) at 4.2 K 

Fe-O
α-Fe"$# %%<=

Velocity (mm/s)

 

Intensity (arb.units)"$# %&A BC DA(BE F G H

3$4 5(6(d) Sample(e) at RT       














Velocity (mm/s)

Fig. 2. Mössbauer spectrum of the samples in the nitridation processesMössbauer spectra for samples (a) and (b) recorded at room temperature are show in Figs. 2 (a) and(b). The sample(e) was measured first at 4.2K in high vacuum, and after exposing in air, data were taken
at room temperature (Figs. 2 (c) and (d)). The spectrum for the starting material (Fig.2(a)) shows that afraction of Fe2.5+ and Fe3+ was reverted compared with that for stoichiometric Fe3 O4 . This result implies
a presence of vacancies in Fe site. The spectrum for the reduced particles (Fig.2 (b)) was fitted to a subspectrum corresponding to α-Fe (81 %) and a doublet (19 %). The doublet may originate in surface oxides
produced during the sample handling in the air. The thickness of the surface oxide is estimated to be 8.8
nm. We obtained 89 % of γ’-Fe4 N and oxide fraction of 11 % in the nitride sample(e) at 4.2K (Fig. 2(c)).
The thickness of the surface oxide is about 5.0 nm. From the room temperature experiment after exposing
the sample(e) in air, the fraction of γ’-Fe4 N degreased to 84 % and the fraction of iron oxide increased.
The thickness of the surface oxide was about 7.5 nm.
In conclusion, we fabricated spherical sub-micron γ’-Fe4 N particles using the successive nitriding
technique and proved that it was in an almost single phase with Mössbauer spectroscopy.

References[1] J. M. D. Coey and P. A. I. Smith, J. Magn. Magn. Meter., 200, 405-424 (1999).

29

3.7

Molcular dynamics calculation of water clusters

T.Ikuyama and I.Arai
We have carried out Molecular Dynamics(MD) calculation [1] for water cluster as a preliminary work
for a study of hydrate cluster. In present study, we are interested in the structure of small water cluster(H2 0)n (n=2-9) which gives a crucial knowledge for the study of hydtrate cluster. In our MD calculation, awater molecule is treated as a rigid body consisting of three piont-like atoms, i.e., two hydrogen atoms andone oxygen atom. Actuallly, we have used SPC/E potential [2] as a two-body effective potential amongwater molecules.
The results are as follows. The dimer forms a linear hydrogen bond as expected (type-2). The trimer
makes a triangular shape (type-3). The tetramer is a regular tetrahedron (type-4) which is formed byputting one extra water molecule above the mass center of type-3. The pentamer exhibits two types ofstructures. One is a triangular dipyramid (type5-1) and the other is a square pyramid (type5-2). The
hexamer exhibits three types of structures. One is a regular octahedron (type6-1), the next is a cage
(type6-2) and the last is a triangular prism (type6-3). The heptamer exhibits two types of structures. One
is a prism shape with one triangular base and one rhombic base (type7-1) and the other is a pentagonal
dipyramid (type7-2). The octamer exhibits two types of structures. One is a rhombic prism (type8-1)
and the other is a hexagonal dipyramid (type8-2). The nonamer exhibits three types of structures. One
is a threefold-stacked triangular prism (type9-1), the next is a cage consisting of a prism shape with one
triangular base and one pentagonal base and one extra molecule on the top(type9-2) and the last is a cage
consisting of a prism shape with one rhombic base and one trapezoidal base and one extra molecule in the
midpoint of the trapezoidal base’s long side(type9-3).
In the present study, the search for stable structures was made by hand without any efficient strategy.
For further study of stable structures, more efficient approach such as genetic search should be introduced.

References[1] F.Cleri and V.Rosato, Phys. Rev. B, 48, 22 (1993).
[2] H.J.C.Berendsen, J.R.Grigera, and T.P.Straatsma, J. Phys. Chem. 91, 6269 (1987).

30

type-2

type-3type-4

type5-1

type5-2

type6-1

type6-2

type6-3

type7-1

type7-2

type8-1

type8-2

type9-1

type9-2

type9-3

Fig. 1. The result of calculation

31

3.8

Simulation of gas aggregation cell by DSMC method

Y. Ito and I. Arai
We have developed a magnetron-sputter-type gas aggregation cluster source. This type of cluster
source can generate clusters of high-melting point metal. In addition, the cluster source is smaller thanour previously developed one. The apparatus is functionally divided into two parts, i.e., a magnetron
sputtering part and a gas aggregation cell. In the magnetron sputtering part, ionized Ar atoms sputter thesurface of the target mounted on the magnetron cathode producing a number of monomer atoms. The
monomer atoms aggregate together into clusters in the gas aggregation cell, which is cooled by liquid
nitrogen and is filled with carrier gas, i.e., a mixture of Ar and He. In the previous studies, it was foundthat the carrier gas could not flow smoothly in the aggregation cell. The reason was considered that the
inlet position of carrier gas was located at the off-axial position. In deed, such asymmetry is thought
to cause serious effect on the flow of carrier gas, resulting in strong suppression of cluster growth andyield. It is necessary to study further by taking account of real gas flow in the gas aggregation cell. To
simulate the real gas flow as precisely as possible, we adopted a Direct Simulation Monte Carlo (DSMC)
method[1]. Fig. 1(a) shows a result of DSMC calculation for the present configuration. In the figure,it is found that the velocity in x direction is negative around the target. This fact means that the carriergas doesn’t transport the monomer atoms around the magnetron in the present configuration as expected.
Fig. 1(b) shows a result of DSMC calculation for the improved configuration, in which the inlet position
is located at around the central axis. In the figure, the carrier gas flows smoothly from the inlet to theoutlet, passing through the iris and the skimmer. These results of DSMC calculations suggest that the inlet
position of carrier gas is very important for the proper operation of gas aggregation cluster source. The
improved configuration is expected to enhance the cluster growth and yield.
x velocity [gas inlet 0m - 0.0045m]

x velocity [gas inlet 0.0285m - 0.0295m]
0.03
0.025
0.02
y [m]

0.03

200
150
100
50
0
-50
-100

0.015
0.01

0.02
y [m]

0

0.015
0.01

z [m/s]

0.005

0.005
0

800
700
600
500
400
300
200
100
0
-100
-200

0.025

0.01

0.02

0.03

0.04

0.05

0

0.06

z [m/s]

0

0.01

0.02

0.03

x [m]

x [m]

(a)

(b)

0.04

0.05

0.06

Fig. 1. Simulation of carrier gas (Ar) flow. The x direction is cell length and the y direction is cell radius.
Magnetron cathode is x=0m, y=0m∼0.0045m. Iris is x=0.048m, y=0m∼0.0075m and skimmer isx=0.06, y=0m∼0.005m. (a)Insert position is x=0m, y=0.0285m∼0.0295m. (b)Insert position is
x=0m, y=0m∼0.0045m.

References[1] G. A. Bird, Molecular Gas Dynamics and the Direct Simulation of Gas Flows, (Oxford:Clarendon
press)(1994)

32

4.
ACCELERATOR MASS SPECTROMETRY

4.1

Cosmogenic 36Cl measurements in the Dome Fuji ice core, Antarctica

K. Sasa, Y. Matsushi3, Y. Tosaki, M. Tamari, T. Takahashi, M. Matsumura, K. Sueki, Y. Nagashima, H.
Matsumura1, N. Kinoshita1, K. Bessho 1 , K. Horiuchi2, H. Matsuzaki3, Y. Shibata4, M. Hirabayashi5and H. Motoyama5
We have measured cosmogenic nuclide 36Cl in the ice core from the Dome Fuji station, Antarctica(39°42'12''E, 77°19'01''S, 3810 m a.s.l) [1]. 36Cl is a long-lived radionuclide with a half-life of 301 kyr. It ismainly produced in the stratosphere through spallation of 40Ar by energetic primary and secondary cosmic
rays. The global mean production rate of 36Cl has been estimated to be ~20 atoms m−2 s−1 [2].
The samples were mainly ice chips by-produced
from the core trimmings for electrical conductivity

Original ice

measurements. The sample size was 0.1 to 1 kg,
Melting
Aliquot extraction

corresponding to the core length of 0.5 to 7 m per
sample. The melted ice samples were spiked with

Sample for Cl meas.

0.75–2 mg of Cl carrier, as 36Cl/Cl ratio was to be

HNO3 addition

10−13–10−14. Chloride ions in the sample wereadsorbed on an anion exchange column and thenBe, Al, Cl carrier
addition
Sample size?
Small(< 175 ml)

eluted with HNO3. Finally, the sample wasprepared as AgCl for AMS. Fig. 1 shows a sample

Large (> 175 ml)

preparation scheme of ice samples for 36Cl AMS.

Cation and anion
exchange

The

36

Cl measurements were performed byaccelerator mass spectrometry at the University of
AgNO3 addition

Tsukuba [3], for about 150 samples to date. The

Concentrated solution

measurement precision was typically ± 7–8 %,Centrifugation

estimated by the propagation of the reproductive
error and the statistical error. Fig. 2 shows typical

Precipitate (AgCl)

36

Cl spectra for 36Cl measurements of a standard

Washing with H2O
and C2H5OH

sample (A), an ice sample (B) and a chemicalblank (C). We usually used standard samples [4] of
36

Cl/Cl = 1.00×10−11 and 1.60×10−12 for ice

Dry upsamples. The background with chemical blanks

Press

was better than 1 × 10−14 for the 36Cl/Cl ratio.

Fig. 1 Sample preparation scheme of ice samples

The 36Cl concentrations in the ice ranged from 2

for 36Cl AMS.

× 104 atoms g−1 at the last glacial maximum to 1

1

Radiation Science Center, High Energy Accelerator Research Organization
Hirosaki University
3
Micro Analysis Laboratory, Tandem Accelerator, The University of Tokyo
4
National Institute for Environmental Studies
233

× 103 atoms g−1 at the bottom of the core. The
concentrations were converted to apparent 36Cl flux
onto the ice sheet, by using snow accumulation
rate[5] as a function of oxygen isotope ratio (δ18O).
The apparent 36Cl flux shows a clear decay profile
throughout the core, being consistent with themodel age-scale. The monotonic exponential
decrease ensures the undisturbed stratigraphy ofthe core in spite of the increasing inclination of theice layers below the depth of 2500 m. The 36Cl flux
seems to have been essentially constant at about
1–3 × 104 atoms cm−2 yr−1 (3–9 atoms m−2 s−1) forthe past 720 kyr. This flux accords fairly with thevalue expected from latitudinal dependence of thenuclide fall-out.
The initial 36Cl concentrations in the samples ofδ18O > −55‰ showed slightly larger values thanthose expected from dilution during the interglacial
periods. This implied the shift in the relationshipbetween the moisture flux through the Antarctic air
mass and isotopic composition of the vapor
supplied

onto

the

ice

sheet

duringtheglacial–interglacial transitions. The cosmogenic
nuclide variations in the ice core have a potential
for reconstructing various earth’s environments,

Fig. 2 36Cl spectra for 36Cl measurements of anot only the history of geomagnetic field intensity

standard sample (A): 36Cl/Cl = 1.60×10−12, anor solar activity, but especially paleo-conditions of

ice sample (B) and a chemical blank (C).

polar atmospheric circulation.

Acknowledgements
This work is supported in part by the Grants-in-Aid for Scientific Research Program of the Ministry of
Education, Culture, Sports, Science and Technology, Japan.
References[1] H. Motoyama, Scientific Drilling 5, (2007) 41–43.
[2] D Huggle et al., Planetary and Space Science 44 (1996) 147–151.
[3] K. Sasa et al., Nucl. Instr. and Meth. B 259 (2007) 41–46.
[4] P. Sharma et al., Nucl. Instr. and Meth. B52 (1990) 410–415.
[5] K. Satow et al., Polar Meteorol. Glaciol., 13 (1999) 43-52.

5

National Institute of Polar Research

34

4.2

Residence times of spr ing water s on the foot of Mt. Fuji, estimatedfrom bomb-produced 36Cl

Y. Tosaki, N. Tase, K. Sasa, T. Takahashi and Y. Nagashima
Bomb-produced 36Cl is a potential dating tool for modern groundwaters [1]. Although it has beenutilized as an indicator of the presence of young water, studies focusing on its application as a dating tool
are particularly infrequent [2]. Therefore, this study aims to provide a methodology on the estimation ofgroundwater residence time using bomb-produced 36Cl. This is the first attempt to quantitatively utilize
bomb-produced 36Cl as a dating tool.
Water samples were collected in the Mt. Fuji area in August 2006 and March 2007. These samples
include 28 spring water samples, and two groundwater samples from artesian flowing wells. Bicarbonate(HCO3−) concentrations were determined by titration with dilute H2SO4 solution. Other major ions (Na+,K+, Mg2+, Ca2+, Cl−, SO42−, NO3−) were measured by ion chromatography analysis (Ion Analyzer IA-100,
Dkk-Toa). Dissolved SiO2 concentrations were determined with an ICP-AES system (ICAP-757, Nippon
Jarrell-Ash). Stable isotopic ratios ( 18O and D) were measured with a mass spectrometer (MAT252,
Thermo Finnigan). The 36Cl/Cl ratios of the samples were measured with the Tsukuba AMS system.
Figure 1A presents the spatial distribution of measured 36Cl/Cl ratios. The 36Cl/Cl ratios range from
4.3 × 10−14 to 4.12 × 10−13. As shown in Figure 1A, investigated springs and groundwaters were classified
into five regions (i.e. eastern, southeastern, southern and western foots of Mt. Fuji, and foot of Mt.
Ashitaka) using the altitude effect on

18

O values. Relatively high 36Cl/Cl ratios were found in the eastern

part. Several spring waters from the southern foot exhibited high NO3− concentration, which were possibly
under the influence of anthropogenic Cl. Therefore, the samples with high NO3− concentration (>10 mg/L)
were excluded from further analyses.
In order to estimate residence times of these waters, time-series variation of 36Cl/Cl in the Mt. Fujiarea was estimated using the 36Cl fallout data at the Dye-3 site, Greenland [3], and the total
bomb-produced 36Cl fallout obtained for the Tsukuba Upland (2.3 × 1012 atoms/m2) [4]. The 36Cl flux for
1560–1920 AD at the Dye-3 site is 20 ± 6 atoms m−2 s−1 [5], which can be taken as the natural backgroundflux. This value was subtracted from annual values for 1945–1985 [3] to obtain yearly values ofbomb-produced 36Cl fallout at the Dye-3 site. These values were linearly scaled according to the assumed
total fallout of 2.3 × 1012 atoms/m2 to predict the local fallout history of 36Cl in the Mt. Fuji area.
To allow comparison with measured 36Cl/Cl ratios of groundwater samples, the 36Cl fallout values
were converted to the 36Cl/Cl unit using the following mass balance equation [6]:R

F 3.156 10 7
P 10 3 C p 6.022 10 23 / 35.45(1)where R is the measured 36Cl/Cl ratio, F is the 36Cl fallout (atoms m−2 s−1), P is the mean annual
precipitation (mm), and Cp is the Cl− concentration in the precipitation (mg/L).
Typical annual precipitation in the Mt. Fuji area, 2500 mm, e.g. [7], was used as P. The mean value
35

of four measured Cl− concentrations at 780–2390 m in the investigated slopes (0.6 mg/L) [8] was used as
Cp. The natural background 36Cl/Cl ratio in the Mt. Fuji area was then added to the obtained R values. It
was assumed to be 5 × 10−14 from the lower limit of measured 36Cl/Cl ratios shown in Figure 2B. Figure
2A shows the estimated 36Cl/Cl values obtained for the Mt. Fuji area.
As reported in previous studies, e.g. [9], most spring waters around Mt. Fuji originate from confined
aquifers between lava layers or from the aquifer lying over the Older Fuji mud flow, which has low
permeability. Piston flow would therefore be a reasonable approximation in this area. Based on thisassumption, residence times of spring waters can be estimated by comparing Figure 2A and Figure 2B.
Considering the earlier results in 1960s [10], which showed elevated levels of tritium, most of the springwaters would have been recharged in the post-bomb period. Hence, estimated residence times werebasically obtained using the post-peak part of the curve shown in Figure 2A.
Figure 1B shows the distribution of estimated residence times for spring waters and groundwaters.
Residence times of less than 20 yr for the southeastern foot are consistent with previous estimates of ~10
yr by the 3H/3He dating method [11]. Residence times of 25–35 yr estimated for the eastern foot are also inagreement with the fact that higher 3H concentrations (~38 TU) were measured in the eastern foot thanthose of the southeastern foot in 1983 [12]. While, residence times of 25–30 yr obtained for the westernfoot disagree with a high 3H concentration measured in 1969 [13], which indicated bomb-derived 3H.
Four samples from the western foot have 36Cl/Cl ratios of ~1 × 10−13 (Figure 1A), which is more than
twice of the assumed natural background (5 × 10−14). One reasonable explanation for the disagreement inresidence times may be that the natural background level of 36Cl/Cl for the western foot is higher than thatfor other foots under investigation. This can be caused by the difference in the Cl− concentration inprecipitation; lesser stable chloride supply leads to the higher 36Cl/Cl ratio.
Condition of the recharge area (i.e. the natural background 36Cl/Cl ratio, chloride concentration inprecipitation, and mean annual precipitation) has to be known correctly, otherwise errors may be directly
enlarged in estimating residence times. However the results obtained show the fundamental reasonabilityof the method using bomb-produced 36Cl to estimate groundwater residence time.
References[1] H.W. Bentley, F.M. Phillips, S.N. Davis, S. Gifford, D. Elmore, L.E. Tubbs, H.E. Gove, Nature 300(1982) 737.
[2] Y. Tosaki, N. Tase, G. Massmann, Y. Nagashima, R. Seki, T. Takahashi, K. Sasa, K. Sueki, T.
Matsuhiro, T. Miura, K. Bessho, H. Matsumura, M. He, Nucl. Instr. and Meth. B 259 (2007) 479.
[3] H.-A. Synal, J. Beer, G. Bonani, M. Suter, W. Wölfli, Nucl. Instr. and Meth. B 52 (1990) 483.
[4] Y. Tosaki, N. Tase, M. Yasuhara, Y. Nagashima, K. Sasa, T. Takahashi, Hydrol. Res. Lett. 2 (2008) 9.
[5] H.-A. Synal, J. Beer, G. Bonani, Ch. Lukasczyk, M. Suter, Nucl. Instr. and Meth. B 92 (1994) 79.
[6] J.N. Andrews, W.M. Edmunds, P.L. Smedley, J.-Ch. Fontes, L.K. Fifield, G.L. Allan, Earth Planet. Sci.
Lett. 122 (1994) 159.
[7] S. Yamamoto, Geogr. Rev. Japan 43 (1970) 267 (in Japanese with English abstract).
[8] T. Hiyama, A. Sato, M. Yasuhara, A. Marui, Y. Suzuki, S. Takayama, Bull. Environ. Res. Cent. Univ.
36

Tsukuba 20 (1995) 45 (in Japanese with English title).
[9] R. Tsuchi, in: Aramaki, S., Fujii, T., Nakada, S. and Miyaji, N. (Eds.), Fuji Volcano, Yamanashi
Institute of Environmental Sciences, Fujiyoshida, 2007, p. 375 (in Japanese with English abstract).
[10] T. Ochiai, H. Kawasaki, Bull. Agric. Eng. Res. Stn. 8 (1970) 67 (in Japanese with English summary).
[11] Y. Mahara, T. Igarashi, Y. Tanaka, J. Groundwater Hydrol. 35 (1993) 201 (in Japanese with English
abstract).
[12] R. Yoshioka, K. Kitaoka, N. Koizumi, J. Groundwater Hydrol. 35 (1993) 271 (in Japanese withEnglish abstract).
[13] H. Kawasaki, J. Jap. Assoc. Groundwater Hydrol. 20 (1978) 117 (in Japanese with English abstract).

(A)

(B)

36 Cl/Cl (× 10 –15 )Residence time (yr)Spring water (Aug. 2006)

Groundwater (Aug. 2006)

Spring water (Mar. 2007)

Spring water (Mar. 2007)

Mt. Fuji

130

Tenshi 124
Mts.

East

Tenshi 25–30
Mts.

South
(62)
(39)
53 96
121
65
(42)
N

314

412
201

105

East
South

Mt. Hakone

202

N

30
30

Mt. Hakone

Mt. Ashitaka<20 25–30

99

35

25–30

25–30
>55

61 67
(52)
(42)
78

<20

25–30

<20 <20<20

113 217

51

South
-east

68
70

43

Suruga Bay

West

25–30 25–30

Mt. Ashitaka
70

Mt. Fuji

25–30

70

West

109 129

Spring water (Aug. 2006)

Groundwater (Aug. 2006)

0

5

25–30 30

<20
<20

Suruga Bay

10 km

South
-east

<20
<20

0

5

10 km

Figure 1. (A) Spatial distribution of 36Cl/Cl ratios in spring waters and groundwaters in the Mt. Fuji area.
Values in parentheses represent the samples with high NO3− concentration (>10 mg/L). (B) Spatial
distribution of residence times of spring waters and groundwaters, estimated from 36Cl.

(A)

(B)

500
East
Southeast
Mt. Ashitaka
South
West

300

200

36

Cl/Cl (10 –15 )

400

100

0
1940 1950 1960 1970 1980 1990 2000 2010 0

2

4

6

8

10

–

Year

Cl (mg/L)
36

Figure 2. (A) Estimated time-series variation of Cl/Cl in the Mt. Fuji area. (B) Measured 36Cl/Cl ratios inspring waters and groundwaters, plotted against chloride concentration.
37

4.3

Measurement of in situ-produced cosmogenic 36Cl in calcite

Y. Matsushi1 K. Sasa, T. Takahashi, Y. Nagashima and Y. Matsukura
Introduction
Cosmogenic 36Cl in calcite is produced in-situ via 40Ca spallation, muon capture by 40Ca, and absorptionof spallagenic or muon-induced thermal neutron by 35Cl [1]. The nuclide is a geomorphological tool for
quantifying exposure age or denudation rate of limestone surfaces. A correct estimation of the age or raterequires accurate measurement of 36Cl and appropriate scaling of 36Cl production rate, which depend on Cl
concentration in the limestone samples. However, the samples are usually dissolved with nitric acid;
therefore it becomes difficult to measure Cl concentration because of the abundant nitric ions in thesolution. Ion-selective electrode method is an available alternative, but it is often elaborate andtime-consuming for the low pH and low Cl concentration samples. Here we apply isotope dilution method
using a 35Cl-enriched carrier [2]. This methodology enables us to measure Cl content in the samples
concurrently with 36Cl-AMS (Accelerator Mass Spectrometry), without any complicated procedure.
Mater ials and method
Limestone samples for the test analysis were collected from the topmost 5 cm of an exposed pinnacle at
Akiyoshi and Hirao karst areas, Japan (Table 1). The rock samples were crushed and sieved to 0.5–0.125
mm size. Twice of HNO3 leaching eliminated the meteoric 36Cl and other potential contamination,
resulting in ~10% dissolution of the particle surfaces. The leached samples (~10 g) were soaked with ~50
ml of ultrapure water, and dissolved gradually with ~50 ml of 4 mol/L HNO3.
A Na35Cl powder from Aldrich Co. (35Cl purity: 99 atom%) was used as a carrier. Each samples andchemical blanks were spiked with 1.5 mg of 35Cl. Blank A was also spiked with 0.5 mg of normal Cl
carrier, as a test standard of the known content of initial Cl with the natural isotope ratio (Table 1). Cl− inthe samples were recovered as AgCl precipitate and pressed into the cathode cones.
36

Cl-AMS was performed with the Tsukuba AMS-system [3], by using an AMS-standard with the

known 36Cl/Cl ratio of 1.60×10−12 [4]. 35Cl/37Cl ratio was monitored with Faraday cups at the AMS-ion
source. A data-logging system recorded automatically the integrated current of the 35Cl and 37Cl ion-beams,
and 36Cl counts at the final detector, for the every ~3–5 min measurement of the target samples.
Table 1. Samples, carrier spiked, and results of the measurement36
Net rock Carrier wt. (mg Cl) 35 37
Cl/35Cl Initial Cl content 36Cl activity
Sample ID
Cl/ Clwt. (g) Normal Enriched(10−13)(ppm)(105 atom g−1)*
Blank A
–
0.505
1.537
14.6±0.03–
0.530±0.003–
Blank B––
1.516
286±110.07±0.02––
Akiyoshi
9.6688–1.512
24.3±0.1 3.43±0.23
28.1±0.2
10.4±0.7
Hirao
8.9602
–
1.516
21±2
–
37±5
–
*
Weight in mg of the normal Cl carrier calculated from 35Cl/37Cl data.

1

MALT (Micro Analysis Laboratory, Tandem accelerator), The Univ. of Tokyo (E-mail: matsushi@n.t.u-tokyo.ac.jp).

38

Results and discussion
Figure 1 shows the monitored 35Cl/37Cl ratio, with the data from ordinary ‘normal’ samples including
AMS-standards, chemical blanks, and natural samples measured during the latter half of the 2007 period.
The isotope ratio of the ‘normal’ samples exhibited the fairly constant values of 3.16±0.05, which
consistent with the natural 35Cl/37Cl ratio (3.127). The ‘spiked’ samples show distinctly large 35Cl/37Cl
ratios, ranging from 286±11 (Blank B) to 14.60±0.03 (Blank A). The ratio of 286±11 means the 35Cl purityof 99.65±0.01 atom% in the spiked carrier, as is expected from [2].
The 36Cl/35Cl ratio of the Akiyoshi sample was103(3.43±0.23) ×10−13 (Table 1); the background of(7±2) ×10−15 (Blank B) had been subtracted.

Blank B

Unfortunately, the 36Cl/35Cl ratio of the Hirao
sample was not able to be measured, because of the102
Cl/37Cl

severe sulfur contamination.
Cl-spiked sample is calculated to as:

S M 1 N[Cl nat. ] [Cl spike ]M N 1 S

Akiyoshi35

The natural (or initial) content of Cl in a
35

Blank A
Hirao

101

(1)

‘Normal’ samples

where, [Clnat.]and [Clspike]are natural and spiked
total(35+37)Cl (atom), N, S, and M are natural, spiked,

Natural ratio(3.127)100
0

and measured 35Cl/37Cl ratios, respectively. Here,the 36Cl activity is then calculated to as:[ 36 Cl] [Cl spike ]

S N M
RAMS
M N 1 S100 200 300 400 500 600 700 800 900
Runs

Fig.1. 35Cl/37Cl ratios. Vertical lines indicate(2)hiatus between the measurements.

where, [36Cl] is the 36Cl amount in the sample (atom), RAMS is the 36Cl/35Cl ratio obtained by AMS.
Calculation from Eq. (1) overestimates the initial Cl content in the Blank A by ~5% (Table 1). The
reason for this slight discrepancy is not clear at present. The natural Cl content in the Akiyoshi and Hirao
limestones were calculated to be 28.1±0.2 and 37±5 ppm, respectively (Table 1). From Eq. (2), the 36Cl
concentration in the Akiyoshi limestone was calculated to be (10.4±0.7) ×105 atom g−1 (Table 1).
The data in this study provide the initial results of the cosmogenic 36Cl measurement in calcite in Japan.
The isotope dilution method works very well at UTTAC, with a sufficient accuracy for the Cl and 36Cl
quantification. Now we are moving toward a routine application of this methodology for the systematic36

Cl measurement that targets several Japanese karsts under subtropical to subarctic environments.

References[1] J.O.H. Stone et al., Geochim. Cosmochim. Acta 62 (1998) 433.
[2] D. Desilets et al., Chem. Geol. 233 (2006) 185.
[3] K. Sasa et al., Nucl. Instr. and Meth. B259 (2007) 41.
[4] P. Sharma et al., Nucl. Instr. and Meth. B52 (1990) 410.
39

4.4

Depth profile of 36Cl/35Cl induced in the thick concrete shieldin EP-1 beam line at the 12-GeV proton synchrotron facility, KEK

N. Kinoshita 1 , H. Matsumura1, K. Bessho1, Y. Matsushi 2 , K. Sasa 3 , T. Takahashi3, S. Mihara3, T. Oki3, M.
Matsumura3, Y. Tosaki3, K. Sueki3, M. Tamari3 and Y. Nagashima3
Secondary particles are produced by bombarding target and beam damp etc. with primary beamin an accelerator facilities. The secondary particles activate the shielding walls and the various materials
around accelerator. We have measured depth profiles of several radioisotopes in shielding concrete atvarious facilities using a gamma-ray spectrometry. Cl-36, produced in a shielding wall by a thermal
neutron capture and nuclear spallation reaction, is one of candidates to measure an aspect of activation in
the shielding wall with an accelerator mass spectrometry.
The method for preparing Cl-36 AMS targets was described in the previous report [1]. Chloride
ion was extracted from 1 – 20 g of the concretes to 15 – 50 ml of 10 mM nitric acid in a Teflon pressurized
decomposition vessel at 130 oC for 12 hours. The concentration of chlorine in the solution was determinedby ion chromatography. The 36Cl/natCl atomic ratio in the solution was isotopically diluted with a known
amount of NaCl standard solutions (with a natural isotopic abundance). Trace amount of S2- occurring inthe solution was oxidized to SO42- by adding a H2O2 solution, then Cl ion was recovered as AgCl
precipitate by adding AgNO3 solution. After dissolving the AgCl precipitate in an aqueous ammonium
solution, Ba(NO3)2 solution was added to remove sulfur as BaSO4 precipitate. The Cl ion was re-converted
to AgCl precipitate by acidifying with HNO3. It was washed with water, dried and subjected to Cl-36 AMS
at UTTAC, University of Tsukuba [2].
The three dimensional spectrum by an ionization chamber was shown in Fig. 1 as an example.

S-36

CountsCl-36

E (ch)E-ΔE (ch)Fig. 1. Three dimensional spectrum of 150
cm. 36Cl/35Cl atomic ratio was measured tobe 2.2×10-12.

Fig. 2. Depth profile of 36Cl/35Cl atomic ratio (leftscale) and Co-60 activity (right scale).

1

Radiation Science Center, High Energy Accelerator Research Organization, 305-0801 Ibaraki, Japan.
Micro Analysis Laboratory, Tandem Accelerator, University of Tokyo, 113-0032 Tokyo, Japan.
3
Research Facility Center, University of Tsukuba, 305-8577 Ibaraki, Japan.
240

We succeeded in discriminating Cl-36 event from isobar S-36. Depth profile of Cl-36 in the shielding
concrete was shown in Fig. 2 together with a gamma emitting nuclide Co-60, produced by neutron capture
reaction, which was determined with a HPGe detector. Cl-36 could be produced by both a thermal neutron
capture reaction and a nuclear spallation reaction. We could estimate the ratio produced from a thermal
neutron capture and a nuclear spallation reaction. Thermal neutron flux could be estimated from the depth
profiles of Co-60 using a generally reported thermal neutron capture cross section. Radioactivities derived
from the flux and cross sections of 35Cl(n,γ)36Cl by a thermal neutron show the contribution from thethermal neutron capture reaction. Radioactivity, which the contribution from the thermal neutron capture
was subtracted from the measured activity, shows the contribution from the nuclear spallation reaction.
Production ratios were estimated to be approximately 30% from the neutron capture and 70% from thespallation.

References[1] K. Bessho, H. Matsumura, T. Miura, Q. B. Wang, K. Masumoto, T. Tatsuhiro, Y. Nagashima, R. Seki, T.
Takahashi, K. Sasa and K. Sueki, Radiochim. Acta, 94, 801 (2006).
[2] K. Sasa, Y. Nagashima, T. Takahashi, R. Seki, Y. Tosaki, K. Sueki, K. Bessho, H. matsumura, T. Miuraand M. He, Nucl. Instr. Meth. B, 259, 41 (2007).

41

4.5

Chlorine-36 in Gibeon iron meteorite

Y. Oura 1 , F. Hashizume1, M. Ebihara1,Y. Tosaki, K. Sasa, Y. Nagashima, T. Takahashi, M. Tamari,K. Sueki, S. Mihara, T. Oki, Y. Matsushi 2 , H. Matsumura 3 , K. Bessho3, N. Kinoshita3, T. Miura3
Gibeon iron meteorite was found in 1836 in the present Republic of Namibia. Many fragments were
found at the area longer than 400 km and their total weight is estimated to be about 21 tons, a one of the
popular large meteorite. Contents of noble gas stable isotopes, 10Be, and 26Al produced by spallation
reaction by cosmic ray have been analyzed in a lot of specimens. 53Mn and 36Cl concentrations were also
obtained.

Then it was found that Gibeon fragments were classified into two groups by their cosmic ray

exposure age calculated by 10Be/21Ne method. The reason that Gibeon has two exposure ages is still
unclear.

We have been determining 53Mn and 36Cl in Gibeon iron meteorite by neutron activation

analysis and AMS method, respectively, to clarify an exposure history of Gibeon meteorite. And adevelopment of NAA technique to determine trace contents of 53Mn in a deep specimen is also our
objective. Since there is no standard reference material for cosmogenic nuclides to evaluate observed
content values, it is important to determine two nuclides for comparison of their content values each other.
36

Cl contents can give alternative ages based on 36Cl /36Ar method.
Nine samples including a fragment called Railway-A were analyzed. After dissolution of a sample with

Cl and Mn carriers in HNO3, Cl and Mn fractions were separated chemically. For AMS, AgCl precipitates
were prepared and 36Cl/Cl ratios were determined by AMS at the Tandem Accelerator Complex,
University of Tsukuba. The determination of 53Mn was not performed yet.
Eight samples other than Railway-A belong to Group-2, whose exposure ages are younger than Group-1,
and their 10Be contents were already obtained. In Fig.1 the correlation between 36Cl and 10Be contents isshown. In this study the similar correlation was observed for Group-2. The variation for Group-2 is larger
than for Group-1.

101

Nord and Zaehringer [1] reported noble gas isotope contents
in Railway of Gibeon. In their report, however, there is an100

were determined by Prof. Nagao, University of Tokyo.
Consequently exposure ages of 1x107 years and 4x107 years
10

21

36

36

were obtained by Be/ Ne and Ar/ Cl methods, respectively.
So it was evident that Railway was categorized by Group-2.
References

10-1

36

Thus we analyzed Railway to examine it. Noble gas contents

Cl [dpm/kg]

inconsistent between an exposure age and noble gas contents.

10-2
Group-1
Group-2
Group-2(this work)

10-3 -4
10

10-3

10-2
10

[1] R. Nord and J. Zaehringer, Geochimii I Analiticeskoy
Chimii, Akad. Nauk 59 (1972).
1

42

100

101

Be [dpm/kg]

Fig.1 Correlation between 10Be and36
Cl in Gibeon.

Graduate School of Science and Engineering, Tokyo Metropolitan University
Micro Analysis Laboratory, Tandem Accelerator, University of Tokyo
3
Radiation Science Center, High Energy Accelerator Research Organization
2

10-1

5.
INTERDISCIPLINARY RESEARCH

5.1

Development of radiation environment monitors for use in spacecraft

Y. Sasaki 1 , H. Matsumoto1, K. Sasa, Y. Tagishi, Y. Nagashima
The space radiation environment is of primary concern for space engineering because it can damage
electronic devices and structural material on spacecraft, thereby limiting their lifetime. To investigate
radiation effects on spacecraft, we used on-board monitors to observe the orbital radiation environment [1].
Accumulated data related to the space radiation environment are expected to facilitate the development of
reliable spacecraft and contribute greatly to the success of space missions. In fiscal 2007, we manufactured
a new radiation environment monitor system as a component of the Greenhouse gases Observing Satellite.
We calibrated its telescopes using a proton beam from the University of Tsukuba’s 12UD pelletron
accelerator.
Figure 1 and Table 1 show the telescopes under beam testing with their performance specifications.
Figure 2 shows a schematic layout of this testing with a cross-sectional view. As Fig. 2 shows, the telescopes
comprise stacked silicon detectors with a Tantrum collimator. A primary mono-energy beam was irradiatedto a 1-μm-thick Au foil target. A secondary beam scattered at the Au foil was incident on the silicondetectors in the telescopes, having roughly equal energy to that of the primary beam. The beam energy was
adjusted from 4 MeV to 16 MeV in steps.
Through testing, we determined the energy response and energy resolution of the silicon detectors. As
an example, Fig. 3 portrays the energy responses of the silicon detectors installed in the APS-B telescope asa function of the energy deposited.
Table 1. Performance specifications of the telescopes under the beam testing
Parameter
Quantity
Geometric factor (cm2 sr)
Field of view (full angle) (deg)Mass (kg)Dimension (mm)Power (W)

Telescope
APS-A
5
0.04
44
1.3
120×90×65
1.1

Fig. 1. Exterior view of the telescopes

VacuumAir

Au foil 1μm
Primary beam: Proton(4MeV - 16MeV)

Extended figure of
the telescope
Collimator
S1
S2
S3

30deg

Secondary beam

Telescope

Silicon detector stack

Fig. 2. Schematic layout of the beam testing1

Japan Aerospace Exploration Agency

43

APS-B
2
0.06
44
1.3
120×90×86
1.1

100
Energy deposited in S2 + S3 [MeV]

Energy deposited in S1[MeV]

14
12
10
8
6
4

alpha-particles

protons

2
0

90
80
70
60
50
40

alpha-particles

30

protons

20
10
0

0

20

40

60

80
ADC data

100

120

140

0

50

100

150

200

250

ADC data

Fig. 3. Energy responses of APS-B silicon detectors to mono-energy protons incorporated into the responses to alpha-particles resulted from theother experiment

References[1] T. Goka, H. Matsumoto, Measurement of Near Earth Radiation Environment – Overview and Plan –,IAC-06-D5.2.02, 57th IAC, Valencia, 2006.

44

5.2

Micro-PIXE analysis of rare-earth elements in monazite

M. Kurosawa, S. Ishii and K. Sasa
Introduction
Monazite, (Ce, La, Nd, Th)PO4, is an important mineral for resource of rare-earth elements(REE), U-Th-Pb age determination in geological sciences [1], and natural background radiation in coastal
area [2]. Thus, accurate and precise determinations of the chemical compositions are important for thegeological and environmental researches. In the analyses, determinations of all of the REE concentrations
are desirable because relative ratios among the most REE contents are an important indicator for crystal
fractionation, melting, and crystallization sequence in magmatic processes. The determinations of the all
REE contents in the crustal materials are required for evaluation of REE resources. Chemical analyses ofmonazite are often performed by electron microprobe (EPMA) because of the convenience and thereliability. Contents of REE oxide in common monazite are a few to 30 wt% for light REE (La to Eu) andseveral tens to hundreds wt. ppm for heavy REE (Gd to Lu), respectively. Lower quantification limits of
EPMA are about several thousand wt. ppm, so the determinations of the heavy REE are difficult.
For these reasons, we attempted to determine precisely REE contents in monazite by using
particle-induced X-ray emission (PIXE) which is possible to determine most of elements withconcentration of a few wt ppm in solid materials. PIXE analyses are based on energy-dispersive
spectrometry of characteristic X-rays emitted from sample material, so overlaps of several X-ray peaks inthe measured spectrum sometimes occur because of inadequate energy resolution of the X-ray detector.
Thus, a subtraction calculation of X-ray intensities of overlapped peaks from an interest X-ray intensity isnecessary for determinations of the interest elemental concentration. The subtraction requires the accurate
relative line intensities of K and L X-ray peaks and calculations of the relative line intensities modified by
X-ray absorption due to sample matrix. In this study, the subtraction calculations using the reasonable
relative line intensities were reexamined and REE contents in monazite were determined using the new
calculation method.
Subtraction of overlapped X-ray peaks and quantification
Most rare-earth element minerals contain P, Si, Ca, Sc, Ti, Mn, Fe, Y, Zr, Nb, Sn, REE, Hf, Ta, W,
Pb, Th, and U, so several peaks of K and L-X rays of their elements are overlapped in the PIXE spectra.
The overlapping peaks are showing in Table1. The overlapped intensities are subtracted based on X-ray
intensities of Kα and Lα peaks of interest elements and the relative line intensities of Kβ, Lβ1, Lβ2, Lβ3, Lβ4,
Lβ6, Lγ1, Lγ2, Lγ3, and Ll for the Kα and Lα peaks. In this study, data from Scofield [3] and Campbell et al[4] were used for the relative line intensities of K X-rays and data combined Cohen and Harrigan [5] andReis and Jesus [6] were used for the relative line intensities of L X-rays. Relative line intensities of mostelements calculated based on these data and X-ray absorption due to sample matrix agreed well with therelative line intensities observed at the PIXE measurement of several standard materials.
Quantification for elements in monazite was performed by using the model calculation of45

Table 1. Overlapped X-ray peaks at PIXE
measurements of rare-element minerals.
X-ray peak(keV)*
P Kα
2.010
Sc Kα 4.091
Ti Kα
4.511
Mn Kα 5.898
Fe Kα 6.403
Y Kα 14.958
Zr Kα 15.775
Nb Kα 16.615
Ce Lα1 4.840
Pr Lα1 5.033
Nd Lα1 5.230
Sm Lα1 5.636
Gd Lα1 6.058
Tb Lα1 6.273
Dy Lα1 6.495
Ho Lα1 6.720
Er Lα1

6.949

Tm Lα1 7.180
Yb Lα1 7.416
Lu Lα1

7.656

Ta Lα1

8.146

W Lα 1

8.398

Pb Lα1 10.551

Campbell [7]. Intensities of X-rays generated
from a thick solid sample are decreased by theOverlapped X-ray peak
(keV)
(keV)
Y Lβ2 (2.078)
Ca Kβ (4.013)
Sc Kβ (4.461)
Nd Lβ3 (5.823)
Ce Lγ2 (6.326)
Pb Lγ2 (15.097)
Th Lβ2 (15.605)
Y Kβ (16.738)
Ti Kβ (4.932)
La Lβ1 (5.042)
Ce Lβ1 (5.263)
Ce Lβ2 (5.613)
Ce Lγ1 (6.054)
La Lγ3 (6.075)
Sm Lβ1 (6.206)
Fe Kα (6.403)
Sm Lβ2 (6.587)
Gd Lβ1 (6.713)
Gd Lβ3 (6.832)
Tb Lβ1 (6.977)
Tb Lβ3 (7.097)
Nd Lγ2 (6.883)
Sm Lγ1 (7.183)
Dy Lβ1 (7.248)
Tb Lβ2 (7.367)
Sm Lγ2 (7.471)
Ho Lβ1 (7.526)
Dy Lβ2 (7.636)
Gd Lγ1 (7.790)
Tm Lβ1 (8.102)
Tb Lγ1 (8.105)
Tm Lβ3 (8.231)
Tb Lγ2 (8.398)
Tb Lγ3 (8.423)
Tm Lβ2 (8.468)
Hf Lγ1 (10.516)
Lu Lγ3 (10.511)

attenuation of energy of the incident protons andthe absorption of the X-rays by the sample matrix,

Y Lβ3 (2.072)

comparing with results of PIXE measurements for

Ho Ll (5.943)
Ce Lγ3 (6.342)

a thin-film material. In this model, the decrease of

U Lβ6 (15.727)
U Lβ4 (16.577)

volume irradiated by the proton beam are

La Lβ3 (5.143)
La Lβ3 (5.143)
Nd Lβ1 (5.722)
La Lγ2 (6.060)
Nd Lβ2 (6.090)
Sm Lβ3 (6.317)
Mn Kβ (6.493)
Nd Lγ1 (6.604)
Lu Ll (6.753)

beam penetration, the major element composition,

Fe Kβ (7.060)
Gd Lβ2 (7.102)
Nd Lγ3 (6.901)
Ta Ll (7.173)

detector sensitivity determined for each element.

Dy Lβ3 (7.370)
Sm Lγ3 (7.489)

multielement

total X-ray intensities from the whole sample
calculated by considering the beam sizes and thea density of the matrix, their proton-stopping
powers, the X-ray production cross sections, and
the X-ray absorption coefficients. Finally, element
concentrations are calculated based on X-ray
intensities corrected for the decrease and the
The detector sensitivity in this study were
determinedbymeasurements
referenceofsamplesthin-film
andamulti-element reference glass material NIST

Ho Lβ3 (7.653)
Er Lβ1 (7.811)
Gd Lγ3 (8.105)
Er Lβ2 (8.186)

SRM 1412. The thin-film sample was prepared bydropping several standard solutions for ICP
analysis onto a Mylar film and drying the film in

Yb Lβ1 (8.402)
Dy Lγ1 (8.426)

a desiccator. By using the calculation model,
almost trace elements in solid sample at levels of

Lu Lγ2 (10.460)

a few to several thousands ppm can be
determined with the total analytical error of*X-ray energy (Table of Isotope, 8th Ed.)

θ10–15 % [8].

Sample and instrumentation
A monazite used in this study was collected from a pegmatite dyke in a Cretaceous Abukuma
granite body at Ishikawa town, Fukushima Prefecture, northeast Japan. The monazite was an elongatedeuhedral crystal, 3 mm wide x 10 mm length, with yellowish pale brown, and was occurred from a grainboundary of giant microcline in the intermediate zone of the pegmatite. A slightly chemical zoning wasobserved with optical microscope. The sample was cut and double-polished, and then mounted on the slide
glass. The sample surface was coated by a carbon film to avoid electrostatic charging.
The PIXE analyses were performed at the 1MV Tandetron. A 0.1 nA beam of 1.92–MeV proton
was focused to a 24 x 24 mm spot on the sample using slits and magnetic lenses. The beam incidence wasnormal to the sample surface, and the X-ray measurement take-off angle was 45° [9]. The characteristic46

X-rays excited by the incident

105

X-ray Intensity (cts)

104

Sm
Ce

Tb

Nd

Pb

Sm, DyHospectra were recorded by amulti-channel

U
Dy

X-ray-energy detector (Gresham
154 eV at 5.9 keV, and the

Y

Gd
Gd

beam were collected by the Si(Li)Co.) with a nominal resolution of

Th

Nd

103
102

Monazite(Ishikawa)

Ce Nd
Th La
Sm
Ca
P
Gd
Pr

Pb

analyzer.

A

55-μm-thick Mylar film was used

Dy

to attenuate the intense X-rays

101

from the light elements and toprevent the entry into the detector

100

5

10

15

20

X-ray Energy (keV)of protons scattered from samples.
The total charge was determined

Fig.1. PIXE spectrum of monazite from Ishikawa, Japanby integrating the target currents,
and all samples were analyzed tothe integrated charges of 0.15 to 0.37μC. Analytical points were chosen based on optical viewing using a
CCD camera mounted on the microscope [9].
Results
Observed spectrum of the monazite consisted mainly of the K-X ray peaks from P, Ca, and Y, theL-X ray peaks from La, Ce, Nd, Pr, Sm, Gd, Dy, Pb, Th and U, and the M-X ray peaks from Tb, Ho, Pb
and Th (Fig. 1). Determined concentrations of the monazite agreed well with the values determined by
EPMA. In addition, a chondrite-normalized REE pattern of the PIXE result is very smooth and agreed
well with that determined by Laser Ablation-ICP-MS [10]. Hence, the present PIXE values are thought tobe reasonable and accurate. This result indicates a suitable subtraction of overlapped L X-ray peaks frominterest REE peaks. The future works are determinations of REE contents in the other rare-element
minerals using this method and evaluations of granitic pegmatites as a potential REE resource in this area.
References[1] K. Suzuki and M. Adachi, Geochem. J., 25 (1991), 357.
[2] A. K. Mohanty et al., Nucl. Instr. and Meth., B211 (2003), 145.
[3] J. H. Scofield, Phys. Rev., A9 (1974) 1041.
[4] J. L. Campbell et al, Nucl. Instr. and Meth., B43 (1989), 197.
[5] D. D. Cohen and M. Harrigan At. Data Nucl. Data, 34 (1986), 393.
[6] M. A. Reis and A. P. Jesus, At. Data Nucl. Data, 63 (1996), 1.
[7] J. L. Campbell, In: Particle-Induced X-ray Emission Spectrometry (PIXE), John Wiley, (1995) 19.
[8] M. Kurosawa et al., Geostand. Geoanal. Res., 30 (2006), 17.
[9] M. Kurosawa et al., Nucl. Instr. and Meth. B142 (1998), 599.
[10] T. Nakajima and M. Kurosawa, Can. Mineral., 44 (2006), 31.

47

5.3

Ion induced nanoparticle formation in N2/H2O/SO2

M. Fujieda, S. Kanda, M. Matsuoka, M. Imanaka 1 , K. Sasa, S. Tomita, H. Kudo
The mechanism of ion induced nanoparticle formation attracts a lot of attention because of the possible
correlation between the Earth's total low-altitude cloud cover and galactic cosmic ray flux [1]. SO2 gas isbelieved to have an important role in the mechanism. To study the effect of SO2, we irradiated 20 MeV
protons in gas mixture of N2/H2O/SO2, and measured the size distribution of produced nanoparticles. The
experiments were performed with a tandem accelerator at University of Tsukuba. The size distributions
were obtained by measuring the electrical mobility of charged nanoparticle with a differential mobility
analyzer.
Diameter (nm)
10

120

1

7

10

80

6

10

-3

Density (cm )Current (fA)

100

60
40

5

10

+

20

N2/H2O/SO2
N2/H2O

0
-7

10

10

-6

-5

-4

10

10

4

10
-13
10

-3

10

2

-12

10

Electrical mobility (m /V⋅s)

-11

10

-10

10

-9

10

-8

10

-7

10

Beam intensity (A)Fig.1. Electrical mobility spectrum of positively

Fig.2. Density of nanoparticle in N2/H2O andcharged nanoparticle nucleated by irradiation of 20

N2/H2O/SO2,

MeV proton in N2/H2O/SO2
The electrical mobility spectrum of positively charged particle is shown in Fig. 1. The distribution has apeak at electrical mobility of 3×10-6 m2/(V·s), which corresponds to a diameter of about 8 nm. A similar
spectrum was obtained for negatively charged particles. The density of produced nanoparticles is given by
the area under the spectrum, which is shown in Fig.2 as a function of the intensity of the proton beam. It isclearly seen that the density is higher than for N2/H2O by a factor of more than 10. The enhancement isdue to sulfuric acid, that was produced through oxidation reaction of SO2 . The oxidation reaction takes
place with help of OH radicals which are produced by proton irradiation.
References[1] H. Svensmark and E. Friis-Christensen, J. Atoms. Solar Terr. Phys. 59,1225 (1997)

1

RIKEN, Wako, Saitama, 351-0198, Japan

48

6. LIST OF PUBLICATIONS
The publications listed here are those released in the fiscal year 2007 by all the workers listed on p.57.

6.1 Journals
NUCLEAR PHYSICS
1. Kosuke Morita, Kouji Morimoto, Daiya Kaji, Takahiro Akiyama, Sin-ichi Goto, Hiromitsu
Haba, Eiji Ideguchi, Kenji Katori, Hiroyuki Koura, Hisaaki Kudo, Tetsuya Ohnishi, Akira
Ozawa, Toshimi Suda, Keisuke Sueki, Fuyuki Tokanai, Takayuki Yamaguchi, Akira Yoneda,
and Atsushi Yoshida, Experiment on Synthesis of an Isotope 277 112 by 208 Pb+70 Zn Reaction,
J. Phys. Soc. Jpn., Vol. 76, No. 4, p.043201(2007).
2. D.Q.Fang, W.Guo, C.W.Ma, K.Wang, T.Z.Yan, Y.G.Ma, X.Z.Cai, W.Q.Shen, Z.Z.Ren, Z.Y.Sun,
J.G.Chen, W.D.Tian, C.Zhong, M.Hosoi, T.Izumikawa, R.Kanungo, S.Nakajima, T.Ohnishi,
T.Ohtsubo, A.Ozawa, T.Suda, K.Sugawara, T.Suzuki, A.Takisawa, K.Tanaka, T.Yamaguchi,
and I.Tanihata, Examining the exotic structure of the proton-rich nucleus 23 Al, Phys. Rev. C
76, 031601(R) (2007).
3. M. Iijima, Y. Aoki, A. Ozawa, N. Okumura, CDCC analysis of 118 Sn(d, p) reaction below
Coulomb barrier, Nucl. Phys. A 793 (2007) 79-95.
4. M. Notani, H. Sakurai, N. Aoi, H. Iwasaki, N. Fukuda, Z. Liu, K. Yoneda, H. Ogawa, T.
Teranishi, T. Nakamura, H. Okuno, A. Yoshida, Y. X. Watanabe, S. Momota, N. Inabe, T. Kubo,
S. Ito, A. Ozawa, T. Suzuki, I. Tanihata, and M. Ishihara, Projectile fragmentation reactions andproduction of nuclei near the neutron drip line, Phys. Rev. C 76, 044605 (2007).
5. C.B. Moon, C.S. Lee, T. Komatsubara, Y. Sasaki, K. Furuno, Structure of the negative parity
bands in Xe-125, Phys. Rev. C 76 067301 (2007).
6. S.Y. Wang, Y.Z. Liu, Y.J. Ma, T. Komatsubara, Y.H. Zhang, Obsevation of negative-parity highspin states of Cs-126, Phys. Rev. C 75 037302 (2007)

MATERIALS AND CLUSTER SCIENCE

7. P. Hvelplund, B. Liu, S. Brøndsted Nielsen, and S. Tomita, Formation of higher-order fullerene
dianions in collisions with Na atoms Eur. Phys. J. D 43, (2007) 133-136
8. Henning Zettergren, Henning T. Schmidt, Peter Reinhed, Henrik Cederquist, Jens Jensen,
Preben Hvelplund, Shigeo Tomita, Bruno Manil, Jimmy Rangama, Bernd A. Huber, Stabilities
of multiply charged dimers and clusters of fullerenes, J. Chem. Phys. 126, (2007) 224303(1-8)

499. H. Zettergren, H. T. Schmidt, P. Reinhed, H. Cederquist, J. Jensen, P. Hvelplund, S. Tomita, B.
Manil, J. Rangama, B. A. Huber, Even-odd effects in the ionization cross sections of [C60 ]2 and[C60C70 ] dimers, Phys. Rev. A 75, (2007) 051201(R) (1-4)
10. S. Tomita, Y. Sato, M. Ohkubo, M. Ukibe, S. Hayakawa, Pulse height reduction effects ofsuperconducting tunnel junction particle detectors for low-energy light molecular ions, Appl.
Phys. Lett. 91, (2007) 053507 (1-3)
11. Eiji Kita, K. Shibata, H. Yanagihara, Y. Sasaki, M. Kishimoto, Magnetic Properties of CoreShell Type Fe16 N2 Nanoparticles, J. Magn. Magn. Mater., 310 (2007) 2411-2413.
12. Manabu Hasegawa, H. Yanagihara, Yuta Toyoda, Eiji Kita, L. Ranno, Electrical and magnetic
properties of g-Fe2 O3 epitaxial films, J. Magn. Magn. Mater., 310 (2007) 2283-2285.
13. T. Katayama, D. Sekiba, K. Mukai, Y. Yamashita, F. Komori, J. Yoshinobu, Adsorption Statesand Dissociation Processes of Oxygen Molecules on Cu(100) at Low temperature, The Journalof Physical Chemistry C, 111, 15059-15063, 2007
14. D. Sekiba, F. Komori, P. Cortona, Investigation of the surface bands along the X-M line of theCu(100) surface, Physical Review B, 75, 165410-1-7, 2007
15. D. Sekiba, H. Yonemura, T. Nebiki, S. Ogura, M. Wilde, M. Matsumoto, T. Okano, J. Kasagi,
T. Narusawa, S. Kuribayashi, Y. Iwamura, T. Ito, H. Matsuzaki, K. Fukutani, Development andApplication of Micro-beam Nuclear Reaction Analysis for Observation of Hydrogen Distribution, Journal of Vacuum Society of Japan, 50, 574-578, 2007

ACCELERATOR MASS SPECTROMETRY

16. Ming He, Shan Jiang, Yasuo Nagashima, Yaoyun Yanga, Tsutomu Takahashi, Kexin Liuc,
Kimikazu Sasa, Kejun Dong, Shaoyong Wu, Takeshi Matsuhiro, Yuuki Tosaki, Xiaotang Ren,
Riki Seki and Keisuke Sueki, AMS measurement of 26 Al cross section for the reaction 14 N(16 O,α)26 Al,
Nucl. Inst. Meth. B, 259, 629-631, (2007).
17. Yasuo Nagashima, Riki Seki, Kimikazu Sasa, Takeshi Matsuhiro, Tsutomu Takahashi, Yuki
Tosaki, Koutaro Bessho, Hiroshi Matsumura, Taichi Miura, 129 I AMS by a 97 Mo16 O2 molecularpilot beam method, Nucl. Inst. Meth. B, 259, 241-245, (2007).
18. R. Seki, T. Matsuhiro, Y. Nagashima, T. Takahashi, K. Sasa, K. Sueki, Y. Tosaki, K. Bessho, H.
Matsumura, T. Miura, Isotopic ratios of 36 Cl/Cl in Japanese surface soil, Nucl. Inst. and Meth.
B, 259, 486-490, (2007).
19. K. Bessho, H. Matsumura, T. Miura, Q. Wang, K. Masumoto, H. Hagura, Y. Nagashima, R.
Seki, T. Takahashi, K. Sasa, K. Sueki, T. Matsuhiro, Y. Tosaki, Estimation of thermal neutron

50

fluences in the concrete of proton accelerator facilities from 36 Cl production, Nucl. Inst. Meth.
B, 259, 702-707, (2007).
20. Yuki Tosaki, Norio Tase, Gudrun Massmann, Yasuo Nagashima, Riki Seki, Tsutomu Takahashi,
Kimikazu Sasa, Keisuke Sueki, Takeshi Matsuhiro, Taichi Miura, Kotaro Bessho, Hiroshi Matsumura, Ming He, Application of 36 Cl as a dating tool for modern groundwater, Nucl. Inst.
Meth. B, 259, 479-485, (2007).
21. Kimikazu Sasa, Yasuo Nagashima, Tsutomu Takahashi, Riki Seki, Yuki Tosaki, Keisuke Sueki,
Kotaro Bessho, Hiroshi Matsumura, Taichi Miura, Ming He, 26 Al and 36 Cl AMS system at the
University of Tsukuba: A progress report, Nucl. Inst. Meth. B, 259, 41-46, (2007).
22. B. Zhou, Y. Nagashima, S. Jiang, W. Wu, Y. Guan, S. Wu, M. He, J. Yuan, X. Ruan, R. Seki,
K. Sasa, T. Takahashi, Y. Tosaki, Y. Matsushi, M. Tamari, and K. Sueki, An improved method
for 129 I-AMS measurement, Nuclear Electronics & Detection Technology (China), Vol. 27(4),740-744, (2007).
23. Yuki Tosaki, Norio Tase, Masaya Yasuhara, Yasuo Nagashima, Kimikazu Sasa and Tsutomu
Takahashi, An Estimate of Local Bomb-Produced 36 Cl Fallout Using the Depth Profile of
Groundwater in the Tsukuba Upland, Central Japan, Hydrological Research Letters, Vol. 2,
pp.9-13, (2008).
24. Yasuo Nagashima, Riki Seki, Kimikazu Sasa, Tsutomu Takahashi, An Accelerator Mass Spectrometry by the Large Tandem Electrostatic Accelerator, Journal of the Vacuum Society ofJapan. Vol.50, No.7, 475-479, (2007).

INTERDISCIPLINARY RESEARCH
25. Y. Oguri, J. Hasegawa, M. Ogawa, J. Kaneko and K. Sasa, A Phantom Test of Proton-Induced
Dual-Energy X-Ray Angiography Using Iodinated Contrast Media, International J. of PIXE
Vol.17, Issue 1/2, 11-21, (2007).

51

6.2 International conferences

1. Kimikazu Sasa (Invited talk), Cosmogenic Cl-36 measurements with the Tsukuba AMS systemand the application as a dating tool for Antarctic deep ice core. Kochi University-KIGAMInternational Symposium, Kochi University, 21-22 February, 2008.
2. Kimikazu Sasa, Satoshi Ishii, Masanori Kurosawa, Micro PIXE system for trace element analysis of single fluid inclusions in mineral samples, 9th European Conference on Accelerators in
Applied Research and Technology, September 3-7, 2007, Florence, ITALY.
3. K. Sasa, Measurement of 36 Cl with the Tsukuba AMS system: its applications in earth and environmental sciences, The 2nd East Asia Accelerator Mass Spectroscopy Conference, the Seoul
National University and the KIGAM (Korea Institute of Geology and Mineral Resources), 2223 October, 2007.
4. Seung Jun Yu, Yoshimichi Ohki, Makoto Fujimaki, Kouichi Awazu, Junji Tominaga, Kimikazu
Sasa, Tetsuro Komatsubara, Reduction of Polarization Dependent Loss of a Planar Optical
Waveguide using Ion Implantation, MRS(Materials Research Society) 2008 Spring meeting,March 24-28, Moscone West and San Francisco Marriott.
5. S. Tomita, M. Imanaka, S. Kanda, M. Fujieda, K. Sasa and H. Kudo, Formation of nanodropletsfrom N2/H2O by irradiation of 20 MeV protons, ISIAC2007, 20th International Symposium
on Ion - Atom Collisions, XX ISIAC, August 1-4, 2007, Agios Nikolaos, Crete, GREECE.
6. T. Komatsubara, K. Sasa, M. Kurosawa, S. Ishii, Y. Yamato, K. Ebisu, T. Kawamata, Hydrogen analysis by proton-proton elastic recoil coincidence spectrometry, International Nuclear
Physics Conference, Tokyo, Japan, June 3-8, 2007
7. A. Ozawa, Mass measurements by isochronous storage ring in RI beam factory, International
Nuclear Physics Conference, Tokyo, Japan, June 3-8, 2007
8. K. Hara, Photonuclear reaction cross sections for 37 Cl and 152 Sm, International Nuclear Physics
Conference, Tokyo, Japan, June 3-8, 2007
9. Y. Yasuda, Measurement of deep hole states in 39 K by (p,2p) reaction at Ep=392 MeV, International Nuclear Physics Conference, Tokyo, Japan, June 3-8, 2007
10. M. Iijima, 118 Sn(d,p) reaction below Coulomb barrier International Nuclear Physics Conference, Tokyo, Japan, June 3-8, 2007
11. D. Sekiba, H. Yonemura, T. Nebiki, S. Ogura, M. Wilde, M. Matsumoto, T. Okano, J. Kasagi,
T. Narusawa, S. Kuribayashi, Y. Iwamura, T. Ito, H. Matsuzaki, K. Fukutani, Micro-beam NRA
for 3D mapping of hydrogen distribution in solids (oral), 18th International Conference on Ion
Beam Analysis (Hyderabad, India, 23 September 2007)52

7. THESES

M. Sc. Theses
Suguru Kanda

Mechanism of droplet formation induced by proton irradiation

Makoto Minagawa

Synthesis and magnetic properties of iron nitride particles
prepared from sub-micron sized Fe3 O4 particles

Kazuya Ebisu

Improvement of hydrogen analysis by using high energy
proton micro beam

Tetsuaki Moriguchi

Studies of Hybrid Photo Detector to measure time-of-flightof RI beams

Tomohito Kawamata

Effect of multiple scattering in ERCS hydrogen analysis

Yuhei Hashizume

Measurements of momentum distributions of fragments from
C isotopes located near the neutron drip line

Takeshi Hoya

Measurements of reaction cross sections of 3 He and 3 H
at intermediate energies

53

8. SEMINARS
Date
2007

Title and SpeakerMay

9

Unstable nucleus 151 Sm and s-process
Kaoru Hara (Univ. of Tsukuba)

Oct

12

Penning trap mass spectrometry of short-lived isotopes
Peter H. Schury (RIKEN)

Oct

16

Tevatron optics measurements using an AC dipole
Ryoichi Miyamoto (Texas Austin)

Oct

26

The measurment of 41 Ca with AMS and its application at CIAE
Jiang Shan (CIAE)

2008
Jan

9

Improvement of hydrogen analysis by using high energy proton micro beam
Kazuya Ebisu (Univ. of Tsukuba)Jan

9Development of high voltage control system and performance evaluationof transition radiation detector for LHC-ALICE experiment
Kengo Watanabe (Univ. of Tsukuba)

Jan

16

Studies of Hybrid Photo Detector to measure time-of-flight of RI beams
Tetsuaki Moriguchi (Univ. of Tsukuba)

Jan

16

Evaluation of Multi-Gap Resistive Plate Chamber for the use of HighEnergy Heavy Ion Collision Experiments
Takanori Sato (Univ. of Tsukuba)

Jan

23

Effect of multiple scattering in ERCS hydrogen analysis
Tomohito Kawamata (Univ. of Tsukuba)

Jan

30

Measurements of momentum distributions of fragments from C isotopes
located near the neutron drip line
Yuhei Hashizume (Univ. of Tsukuba)

Jan

30

Measurements of reaction cross sections of 3 He and 3 H at intermediate energies
Takeshi Hoya (Univ. of Tsukuba)

Feb

13

Systematic study of azimuthal anisotropy for PID charged Hadrons
in relativistic heavy ion collisions
Maya Shimomura (Univ. of Tsukuba)

Mar

12

Recent development of AMS study in China Institute of Atomic Energy
He Ming (CIAE)

54

9.

SYMPOSIA
Workshop on ”r-process nucleosynthesis and quantum beam”
13,14 March, 2008
University Hall, Conference Room
hosted by National Astronomical Observatory of Japan
1. Opening : A. Ozawa (Univ. of Tsukuba)
2. What would be the best method for producing nuclei along the r-process path? : I. Tanihata(RCNP)
3. Nuclear physics studies for r-process nucleosynthesis at RIKEN RI Beam Factory : T. Motobayashi (RIKEN)
4. Present status of Rare-RI Ring : Y. Yamaguchi (RIKEN)
5. Recent developments on low-energy radioisotope beam production at CNS-CRIB : H. Yamaguchi (CNS)
6. Nucleosynthesis study with real photon beams : H. Utsunomiya (Konan Univ.)
7. Investigation of origin of p-process isotopes using reactor neutrons, laser Compton scattering
gamma-rays and tandem ions : T. Hayakawa (JAEA)
8. Study of nuclear synthesis of 26 Al by gamma ray spectroscopy : T. Komatsubara (Univ. of
Tsukuba)
9. Systematic calculations of electric dipole response with mean-field approach : T. Itakura (Univ.
of Tsukuba)

10. Fission barrier for heavy neutron-rich nuclei using with Skyrme-Hartree-Fock : F. Minato (Tohoku Univ.)
11. 118 Sn(d,p) reaction below Coulomb barrier : M. Iijima (Univ. of Tsukuba)
12. Astrophysical nuclear reactions and cluster models : K. Kato (Hokkaido Univ.)
13. Big bang nucleosynthesis catalyzed by a SUSY-particle stau : M. Kamimura (Kyushu Univ./RIKEN)
14. Nuclear astrophysics at TRIAC facility : H. Miyatake (KEK)
15. Present status of 12 C+4 He→16 O+ γ experiment at KUTL : K. Sagara (Kyushu Univ.)
16. Measurement of the E1 and E2 cross sections of the 12 C(α,γ)16 O reaction using pulsed alphabeams : H. Makii (JAEA)
17. Explosive nucleosynthesis in GRB : T. Kajino (NAO)
18. Supernova explosion and nucleosynthesis : G.J. Mathews (Univ. Notre Dame)
19. Supernova neutrino nucleosynthesis : T. Yoshida (NAO)
20. The r-process in neutrino-driven winds : S. Wanajo (Tokyo Univ.)
21. Neutron capture elements and astronomical observation : W. Aoki (NAO)
22. Closing : T. Kajino (NAO)

55

Annual meeting of UTTAC users
Seeds for new application of high quality ion beams- Tendency and Results of the UTTAC Research Works 2007 17 March, 2008
Laboratory of Advanced Research B 0110
1. Opening : H. Kudo (Univ. of Tsukuba)
2. Origin of life and synthesis of orgamic matter with particle irradiation on quasi-cosmic dust
(Invited) : N. Kobayashi (Yokohama National Univ.)
3. Li diffusion studies in lithium ionic conductors using the short-lived radiotracer of 8 Li (Invited): S.C. Jeong (KEK)
4. Present status of production of 8 Li at UTTAC : K. Hara (Univ. of Tsukuba)
5. Research for excited states in 26 Si : T. Komatsubara (Univ. of Tsukuba)
6. Supernova neutrino-process nuclide 138 La : T. Hayakawa (JAEA)
7. Average charge and its structure dependence of carbon cluster ion under irradiation of thin foils(Invited) : A. Chiba (JAEA)
8. Energy loss of fast cluster ions in thin carbon foils : S. Tomita (Univ. of Tsukuba)
9. Waveguide mode biosensors fabricated with swift heavy ions : K. Awazu (AIST)
10. Effects of ionized radiation from the outer space for the stratosphere : What we may explore
through laboratory experiments (Invited) : Y. Nakai (RIKEN)
11. Water droplet formation under irradiation of proton beam : M. Imanaka (RIKEN)
12. Accelerator Mass Spectrometry and its application for earth environmental sciences (Invited) :H. Matsuzaki (Tokyo Univ.)
13. Cosmogenic 36 Cl variations over the past 720 kyr in the Dome Fuji ice core, Antarctica : K.
Sasa (Univ. of Tsukuba)
14. In-situ-produced cosmogenic 36 Cl in calcite : Y. Matsushi (Tokyo Univ.)
15. Analysis of Chlorine-36 in meteorite : Y. Oura (Tokyo Metropolitan Univ.)
16. In situ observation of defect production during ion irradiation by positron annihilation spectroscopy (Invited) : H. Tsuchida (Kyoto Univ.)
17. Point defects in Er-doped GaN probed by a monoenergetic positron beam (Invited) : A. Uedono(Univ. of Tsukuba)
18. Micro-analysis of hydrogen near metal surface by using ERCS and NRA : D. Sekiba (Univ. of
Tsukuba)
19. PIXE analysis of liquid inclusion : M. Kurosawa (Univ. of Tsukuba)

56

10. LIST OF PERSONNEL
Tandem Accelerator Complex
H. KudoT. Komatsubara
K. Sasa
D. Sekiba
S. Ishii
H. Kimura
H. Oshima
Y. Tajima
T. Takahashi
Y. Yamato
Y. Tagishi
Y. Nagashima
K. HaraS. Mihara
T. OkiY.J. Guan
M. Matsumura
M. MoroDirector, Professor
Assistant Professor
Assistant Professor
Assistant Professor
Mechanical Engineer
Computer Engineer
Electric Engineer
Mechanical Engineer
Electric Engineer
Electric Engineer
Research Coordinator
Research Coordinator
Research Fellow
Research Fellow
Research Fellow
Research Fellow
Technical Assistant
Administrative Stuff

Steering Committee
H. KudoA. Ozawa

Y. Miake
T. Komatsubara

T. Sakae
K. Sasa

K. Matsukura
D. Sekiba

K. Murakami

T. Komatsubara

M. Onoda

A. Ozawa

K. Sasa

E. Kita
A. Uedono

H. KudoH. Yanagihara

T. Makimura

H. Mizubayashi

H. Tanimoto

Research Members 1
Inst. of Physics
I. Arai
Y. YasudaInst. of Applied Physics
S. AokiK. Akimoto
T. Suemasu
S. Tomita
Inst. of Materials Science
T. Kondo

J. Nakamura

Inst. of Engineering Mechanics and Systems
K. Matsuuchi
1 The ”research members” include the authors and coauthors within 5 years back from this fiscal year, as well as themembers of research projects runnning at UTTAC.

57

Inst. of Geoscience
M. Kurosawa

N. TaseInst. of Chemistry
K. Sueki

Graduate students
Doctoral Programs of Pure and Applied Science
H. Arai
S. Igarashi
M. Iijima
M. Konno
H. Masui
K. Miki
J.P. OhM. OkaJ.W. Seo
H. Tanaka
K. Yamaguchi
Master’s Programs of Pure and Applied Science
K. Ebisu
M. Fujieda
Y. Funagi
Y. Hashizume
T. Hoya
K. ItoK. Maeda
T. Maekoya
M. Minakawa
M. Murakami
K. MutoA. Onishi
M. SanoY. SatoN. Seya
A. Sugawara
A. Suzuki
H. Suzuki
K. Watahiki
K. Watanabe
K. YamadaT. Ikeda
T. Miyazawa
M. Shimomura

Y. Ikeda
M. Nakazumi
K. Takao

I. GotoS. Kanda
Y. Mizuguchi
W. Onoda
A. Shimao
M. TamariD. Yoshioka

J. Hagiwara
S. Kouso
T. Moriguchi
D. Sakata
N. Shiobara
N. Umada

M. Honda
M. Kajitani
T. Okuyama
T. Watanabe

M. Horikoshi
Y. Kaku
T. Shiba
T. WakiDoctoral Programs of Life and Environmental Sciences
Y. Tosaki
Master’s Program in Education
T. Kawamata
Undergraduates
T. Adachi
T. Ikuyama
M. Matsuoka
Y. SetoH. Yokoyama

E. HamadaY. ItoK. MutoA. Takashima

M. Hashimoto
Ho Jo
K. Ogawa
N. Udeda

58

Scientific Guests and Fellows
K. Awazu
M. Fujimaki
S.J. Yu
K. Sugimoto
H. Aiba
Y. Koganezawa
K. Nomura
A. Maeda
S. Fujii
Y. Matsumoto
H. Muramatsu
K. Bessho
K. Masumoto
N. Kinoshita
I. Sugai
H. Kawakami
M. Oyaizu
Y. Takeda
T. Hayakawa
T. Shizuma
H. Matsuki
T. Komiyama
Y. Sasaki
Y. Terakado
M. Nakazawa
M. KusakabeS. Mizumoto
M. Tomitaka
S. Kubono
H. Yamaguchi
Y. Wakabayashi
S. Hayakawa
Y. Kurihara
Y. Ohura
H. Hashizume
Y. Matsushi
J. AsaiR. Ichimiya
K. Kurita
M. Kawashima
K. Sakashita
N. Okumura
N. Imai
H. Ishiyama
Y. Watanabe
Y. Hirayama
H. SatoAIST
AIST
Waseda Univ.
Waseda Univ.
Waseda Univ.
Waseda Univ.
Waseda Univ.
Waseda Univ.
Waseda Univ.
Tokyo Univ.
KEK
KEK
KEK
KEK
KEK
KEK
KEK
KEK
JAEA
JAEA
JAXA
JAXA
JAXA
Meisei Denki
Meisei Denki
Meisei Denki
Meisei Denki
Meisei Denki
CNS
CNS
CNS
CNS
CNS
Tokyo Metropolitan Univ.
Tokyo Metropolitan Univ.
Tokyo Univ.
RIKEN
RIKEN
Rikkyo Univ.
Rikkyo Univ.
Tokyo Institute of Technology
Nagano College of Technology
KEK
KEK
KEK
KEK
Ibaraki Univ.

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