UTTAC-72, 2004

ANNUAL REPORT
April 1, 2003 – March 31, 2004

TANDEM ACCELERATOR CENTER
UNIVERSITY OF TSUKUBA

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

PREFACE
This annual report covers the work carried out at University of Tsukuba Tandem Accelerator
Center (UTTAC) during the fiscal year 2003 (1 April 2003 ∼ 31 March 2004). The two tandem
accelerators, 12UD Pelletron and 1MV Tandetron, have been operated stably throughout this period,
except for several small troubles.
The main research field with 12UD Pelletron has recently been shifted to the applied accelerator
category from rather fundamental, physics-directed sciences. The accelerator mass spectroscopy of36

Cl has been refined and applied to environmental studies. The hydrogen recoil detection analysis ofmineral samples has been continued in collaboration with geologists. Irradiation effects of fast heavy
ions in the electronic stopping range were applied to fabrication of 3-dimensional nano/microstructureof TiO2. On the other hand, the fundamental studies of nuclear, atomic, as well as condensed-matterphysics are in steady progress. In nuclear physics, the total-reaction cross section for protons on 12C
near the (p,n) threshold and the analyzing powers in the 6Li(d,p)7Li reaction at 90 keV were studied. A
polarized deuteron target was developed for measurement of spin-correlation parameters in D(d,p)
reaction at 20 MeV. In atomic and condensed-matter physics, fundamental data of non-equilibrium
charge states of swift heavy ions are being accumulated for detailed understanding of thecollision-induced charge changing processes.
The 1MV Tandetron has been used routinely for Rutherford backscattering spectroscopy (RBS)of synthesized semiconductor and magnetic films, and for trace-element analysis by particle induced
X-ray emission (PIXE). Besides such applied use, we have successfully accelerated B, C, Al, Si, andCu cluster ions at MeV energies and provided for challenging studies of cluster-surface electronicinteractions.
In the end of this fiscal year, UTTAC successfully organized two workshops entitled
Unstable Nuclei and Nuclear Synthesis with Storage Ring, and Electronic Excitation and Related
Phenomena in Atomic Collisions. Also, eighteen UTTAC seminars were held to stimulate research
activities and to exchange academic information. Notably, UTTAC accepted a series ofaccelerator-facility tour for totally ∼700 visitors this year, of which 390 are high-school students. Such
"open-facility" service is of social importance for promotion of natural science, especially in the next
generation.
The former director of UTTAC, Professor Kohei Furuno, retired from his duty, effective on 1
April 2003. His long-term effort for development and maintenance of the UTTAC facility is greatly
acknowledged. UTTAC restarted this spring as Applied Accelerator Division of Research Facility
Center for Science and Technology. The familiar name UTTAC will be used as before, with Center
replaced by Complex (means multi-accelerator facility).

Hiroshi Kudo
Director-i-CONTENTS
1. ACCELERATOR AND EXPERIMENTAL FACILITIES
1.1

Accelerator operation 2003 ......................................................................................................1

1.2

Design of laser coupling with a compact 2.45GHz ECR ion source........................................5

1.3

Development of the polarized target system for measurement of D ( d , p)T reaction ........7

2. NUCLEAR PHYSICS
2.1

nat

2.2

Differential cross sections and vector analyzing powers in proton

Sn(d,p) reaction in search for Coulomb stripping of deuteron .......................................... 11

elastic scattering from 28Si around neutron threshold energy..................................................13
2.3

Measuring energy dependence of proton total reaction cross section
around neutron threshold energy .............................................................................................15

2.4

Analyzing powers for the 6Li(d,p)7Li reaction at incident energy of 90 keV.........................17

2.5

Proton-induced reaction for heavy elements ..........................................................................22

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

Electron emission induced by fast atom clusters ..................................................................24

3.2

Resonant coherent excitation of C5+ observed with loss electron yield from a Si crystal ......29

3.3

Solid target thickness where energetic ions attain charge equilibrium...................................32

3.4

Structural characterization of thin films by RBS technique ...................................................33

3.5 Molecular beam epitaxy of Si-based ternary alloy
semiconductor Ba1-xSrxSi2 fims on Si(111) substrates ..........................................................35
3.6

Swift heavy ions for nano-fabrication of titanium dioxide.....................................................39

3.7

Absorption of silicon atoms on gold clusters. ........................................................................45

3.8

Charge- and velocity- dependence of charge transfer reaction
between HCI and C60 .............................................................................................................48

3.9 Mössbauer study on Fe nitride fine particles with high coercive force..................................50
3.10

Anelasticity study of nanocrystalline FCC metals ...............................................................55

3.11 The science of 3d transition-metal oxide system (2003-2004) ...........................................59- iii -

4. ION BEAM APPLICATION
4.1

Status of Tsukuba AMS system .............................................................................................63

4.2

Development of a multi gas ∆E - E counter telescope for AMS study ..................................65

4.3

An environmental study with 36Cl contents in the soils from many places in Japan ............68

4.4

Application of 36Cl as a tracer in groundwater hydrology......................................................71

4.5

AMS measurement of 36Cl in shielding concrete of various accelerator facilities.................73

4.6

AMS measurement of the 14N(16O,α)26Al reaction at the near barrier energies.....................75

4.7

Qualitative measurement of hydrogen depth profile by using ERCS
for melt inclusions in quartz crystal ......................................................................................78

4.8

High energy gamma rays from radiative capture reactions ...................................................83

5. LIST OF PUBLICATIONS .....................................................................................85
6. THESES .........................................................................................................................90
7. SEMINARS...................................................................................................................91
8. SYMPOSIA...................................................................................................................92
9. LIST OF PERSONNEL............................................................................................94- iv -

1.1

Accelerator operation 2003

K. Sasa, K. Shima, T. Komatsubara, S. Ishii, H. Kimura, H. Oshima, Y. Tajima, T. Takahashi, Y. Yamato
and H. Kudo.
The 12UD Pelletron tandem accelerator
The total operating time and the experimental beam time were 2047.5 and 1475.4 hours, respectively.
The operating time was about 102 % relative to that in 2002. Figure 1 shows the accelerator operation
hours per month. The beam time histogram with respect to the terminal voltage is shown in Figure 2.
Figure 3 represents percentage operation time of the three ion sources and ion species. Figure 4 shows thepercentage of experimental beam time of the running research fields.

250

150

100

50

0

2003
Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

2004
Jan

Feb

Mar

Figure 1. Accelerator operation hours per month for the fiscal year 2003.

11 MV
10 MV
9 MV
Terminal Voltage

Machine Operation Hours

200

8 MV
7 MV
6 MV
5 MV
4 MV
3 MV
2 MV
0

100

200

300

400

500

600

Beam Hours

Figure 2. Beam time histogram as a function of the terminal voltage.

-1-

AMS
Ion Source
36Cl
8.5

27Al 35Cl
26Al 1.4 4.9
1.6

13C
0.1

1H
28.0 %

Polarized
Ion Source

2H
5.6

SputterIon Source

1H
5.1

127I
0.7
107Ag
0.3
93Nb
0.4
79Br
1.9
63Cu
3.5

2H
9.1

48Ti
0.8
40Ca
0.4

37Cl
0.5
35Cl
2.1

16O
0.8
28Si
0.2

12C
19.2

11B
0.7

7Li
3.5

24Mg
0.7

Figure 3. Percentage operation hours of the three ion sources.

Developments(Instruments &Detectors)
Accelerator Science
1.4%
0.8%
Nuclear Physics(non-polarization)
26.5%

Atomic and Solid
State Physics
32.1%

Nuclear Physics(polarization)
5.6%
Nuclear Physics(unstable nucleus)
9.0%

Earth Science
8.1%

Accelerator Mass
Spectrometry
16.5%

Figure 4. Percentage experimental beam time of the research fields.
The scheduled maintenance was finished on April 1, 2003. After high-voltage conditioning, the beams
have been provided for experiments since May 10. The operation of the 12UD Pelletron tandem
accelerator was in stable operation at the terminal voltage of lower than 10.5 MV in the year 2003. Whenthe terminal voltage is increased to 11MV, the accelerating tubes in the first and second units on the low
energy side have been troubled in the last few years. In the middle of 2003, the terminal voltage could not
be increased more than 10.5 MV. We observed continuous fluctuation of corona currents and X-ray bursts
without shorting the first and second units. High voltage conditionings did not suppress these phenomena.
The scheduled maintenance in the spring 2004 was started on March 3 and finished on April 9. We
replaced the compressed type accelerating tubes by the standard type in the first and second units on the
low energy side at this time. Figure 5 shows the old and new arrangements of accelerating tubes in the firstand second units. Another major works of this maintenance were as follows. All corona points were-2-

renewed along the column and the accelerating tube. Stripper foils in the foil unit-A and B were also
replaced by new foils. We repaired the oiling system, the shorting rod contacts, and the insulating sheets ofthe chain pulley. The vacuum system of the analyzing magnet was modified by replacing the turbo
molecular pump by the ion pump. The power supplies for quadrupole magnets in the second target room
have also been renewed. The 1000 kg SF6 gas was added to the main accelerator tank during the scheduled
maintenance.

Ion beam

Ion beamCompressed type
accelerating tube
(11 gaps)

Standard type
accelerating tube
(11 gaps)
Heating plate

First
unit

ColumnchassisColumnSecondunit

Compressed type
accelerating tube
(8 gaps)

New arrangement (from April 2004)

Old arrangement

Figure 5. Old and new arrangements of accelerating tubes in the first and second units.

The 1MV Tandetron accelerator
The total operation time of the 1MV Tandetron accelerator was 347 hours in the fiscal year 2003. Whilethe usual run for RBS material analysis has been continued throughout the year, the experiments withcluster beams have been increased drastically since Cn (n=1-8) beams of equal velocity (0.24 MeV/u) havebeen successfully provided on June 2003. This technical development allowed us to start a research
program, “Fast cluster impact processes”, including electron emission, sputtering, radiation damage,secondary particle emission. Surely, these are well known phenomena, but our knowledge is restricted
only for impact of single-atom (n=1) ions. So far unknown aspects of these phenomena might be revealed
by cluster impacts through the nano-space perturbation that are never realized by single-atom or small
molecular ions.

For this research program, a variety of cluster beams are required. The transportconditions of the cluster beams have been investigated in detail and are summarized in Table 1.

-3-

Table 1. Experimental conditions of high-energy cluster ions for the B (11°) and C (15°) beam courses.
11

Beam course Energy
15°

●

●

●

43.6 keV/u

480 keV/atom

●

●

●

●

C1+

C2+

C3+

C4+

C5+

C6+

C7+

C8+

●

●

●

12

20 keV/u

240 keV/atom

●

●

●

●

●

30 keV/u360 keV/atom

●

●

●

●

●

42 keV/u504 keV/atom

●

●

●

●

Al1+

Al2+

Al3+

Al4+

●

●

●

●

Si1+

Si2+

Si3+

Si4+

●

●

●

●

27

8.89 keV/u

240 keV/atom

28

8.57 keV/u

240 keV/atom

63

Beam course Energy
15°

B4+

●

Beam course Energy
11°

B3+

320 keV/atom

Beam course Energy
11°

B2+

29.1 keV/uBeam course Energy
11°

B1+

7.62 keV/u

480 keV/atom

Cu1+
●

63

Cu2+
●

References[1] K. Sasa et al., UTTAC71 (2003) 1.

-4-

1.2

Design of laser coupling with a compact 2.45 GHz ECR ion source

K. Sasa
A compact 2.45 GHz electron cyclotron resonance (ECR) ion source was installed for a second stage ofa hybrid ion source [1] as a charge state multiplier and a stable beam extractor. Particles extracted from thesolid sample by the laser ablation have a broad energy distribution and an unstable beam flux. Once thesample materials produced by the laser ablation are trapped in the ECR plasma, the efficient production ofhighly charged ions in the ECR plasma ensures the elimination of molecular ions or micro-particles.
The simple structure of the compact 2.45 GHz ECR ion source was originated by E. Tojyo [2]. The
magnetic field is given by two pieces of Nd-Fe-B permanent magnets, corresponding to a closed
resonance surface of 875 Gauss. A 2.45GHz microwave power and supporting gas are supplied into theplasma chamber in the transverse direction. The inner diameter and the length of the plasma chamber aredesigned to 32 mm and 72 mm, respectively. Figure 1 shows the cross-sectional view of the laser couplingwith a compact 2.45 GHz ECR ion source. Table 1 shows the main characteristics of the compact 2.45
GHz ECR ion source.

Figure 1. Cross-sectional view of the laser coupling with a compact 2.45 GHz ECR ion source.
Table 1 Main characteristics of the compact 2.45 GHz ECR ion source [2].
Extraction voltage

1-10

[kV]

Beam current density> 10[mA/cm2]

Beam aperture

φ 2-3

[mm]

Normalized beam emittance∼ 0.6 πECR zone

φ 19×36[mm mrad][mm3]

Plasma chamber

φ 32×72[mm3]Outer size of main body

φ130×132 [mm3]2.45GHz microwave power

< 1.3

-5-

[kW]

It is possible to inject the sample materials into the ECR zone from the upstream side on the central
beam axis. A laser ablation apparatus [1] is connected with the ECR ion source directly at the upstreamside. A compact Nd:YAG pulsed laser at 1064 nm wavelength with the pulse width of 8 ns and the
maximum energy of 50 mJ is employed to evaporate the sample materials as a means of introducing solid
samples into the ECR plasma. At present, the optical simulation for the drift line is performed to estimate
the trapping efficiency of the laser produced particles in the ECR plasma.
The laser coupling with the ECR ion source will be used for the element-analysis experiments and the
production of multi-charged fullerene beams.
Acknowledgments
The compact 2.45 GHz ECR ion source was installed in overall cooperation with Dr. E. Tojyo (KEK).
This work is supported in part by the Grand-in-Aid for Scientific Research (Encouragement of Young
Scientists (B) - No.14750039) of the Ministry of Education, Science, Sports and Culture.
References[1] K. Sasa, UTTAC71 (2003) 11.
[2] E. Tojyo, et al., Genshikaku Kenkyu, Vol.37, No.3 (1993) 45.

-6-

1.3

Development of the polarized target system for measurement of p)T reaction
D(d,M.Iio1 , I. Daito2, Y. Tagishi, N. Horikawa3, T. Hasegawa1 , T. Iwata4 ,Y. Yamaguchi, T. Shinba, N. Yoshimaru, N. Okumura, Y. Tajima, S. Ishii,
T. Kobayashi 5 , T. Inagaki6 , N. Doshita 6, K. Kondo6
The nuclear fusion process has been expected to be one of the better methods to be able to overcome
the subjects on future insufficient energy sources. 3 He + D nuclear fusion reaction is considered becauseof a less neutron production rate in the reaction process, which minimizes the irradiation damages to thewall of the reactors. However, the neutrons might be generated from the D + D collision process in thehigh temperature plasma of 3 He + D mixture. Then, the use of a polarized nuclear fusion reaction has
been considered to be one of the methods to solve this problem[1].
According to the references, the 3 He + D nuclear reaction proceeds mainly via the 5 Li(3/2+) compound nuclear state, and then the reaction cross section in both 3 He and D being polarized might beenhanced to be about 1.5 times larger than the one of the unpolarized reaction case. Additionally, the D+ D reaction process with both polarized might be much suppressed in the low energy region where thereactions may proceed mainly in S-waves and be forbidden according to the Pauli-principle. Therefore,
the D + D fusion reaction rates would be expected to be enhanced or suppressed if deuterons could bepolarized in the plasma. This is only the theoretical predictions and is not verified realistically yet by any
experiments until now[2, 3, 4].
Thereby, we are now going to measure the possible enhanced spin depend cross sections for the p)T nuclear fusion reaction at 20 MeV now by using a polarized deuteron beam of Tandem AcD(d,celerator Center, University of Tsukuba (UTTAC)[5] and a polarized deuterium target developed mainly
at Nagoya University based upon the so-called dynamic nuclear polarization (DNP) method.
As shown in Fig.1, the present polarized deuterium target system consists of a 3 He-4 He dilution cryostat, a 2.5 T superconducting magnet, a 70 GHz µ -wave irradiation system for DNP method and a NMR
system monitoring the target polarization. The CD2 target is set on the top of µ -wave guide tube andinserted in the mixing chamber (MC) made from glass epoxy so as to be positioned at the center of thesuperconducting magnet. The MC with 1 mm thick inner space is filled with liquid 3 He and 4 He mixture
and able to cool down to the lowest as 250 mK, which temperature is kept to be less than 300 mK forthe 1 nA deuteron beam incidence during the experiment and is consistent with the previously tested andobtained cooling power of 2 mW at 300 mK.
The magnetic field of 2.5 T with the homogeneity of 10−4 in the central part of 5 mmφ is preparedby a superconducting Helmholtz magnet with 5 mm gap, which is enough space for the detection of the
1 Faculty of Engineering, Miyazaki University, 889-2192 Miyazaki, Japan
2 Research Center for Nuclear Physics, Osaka University, 567-0047 Osaka, Japan
3 College of Engineering Chubu University, 487-8501 Kasugai, Japan
4 Department of Physics, Faculty of Science, Yamagata University, 990-8560 Yamagata, Japan
5 Department of Physics, Tokyo Institute of Technology, 152-8550 Tokyo, Japan
6 Department of Physics, School of Science, Nagoya University, 464-8602 Nagoya, Japan-7-

scattered particles by counter telescopes of solid state detectors.

4

Fig. 1. Side views of polarized target system. (A) Longitudinal sections of 3 He-4 He dilution cryostat and2.5 T small superconducting magnet set in the scattering chamber. The deuteron beam comes fromthe left. (B) Central insert of µ -wave guide, coaxial cable for NMR signal detection and polarizedtarget holder. This part is inserted to the center of the cryostat(A).

The polarized target is warmed up by the beam energy loss, which might affect to decrease the target
polarization. The beam energy loss in the target is considered to be larger in the lower energy experiments.
We select the thin solid CD2 foil as a target, in which about ∼5 keV/ µ m of the stopping power is estimatedfor the 20 MeV incident deuterons. The solid CD2 foil with 30∼50 µ m thickness was developed fromhigh pressurized powders under high temperature. As described before, the DNP method[6] is employed
in order to get higher target polarization. Then, it is necessary to make a modification of paramagnetic
centers in the target material. The TEMPO (2,2,6,6,-Tetra-Methyl-Piperidine-1-Oxil) was chosen to be
doped in the CD2 by diffusing method, the optimal density of which was 3×1019 spins/cm3 [7].
The 30∼50 µ m thick CD2 foil was installed in the polarized target system and tested several times inalmost the same experimental conditions with the actual measurement. The typical operation parameters
to polarize the target were as following: temperature of mixing chamber; 0.8 K, magnetic field; 2.5 T, µ wave frequency; 70.03 GHz and the doped density of unpaired electrons; 2.5×1019 spins/cm3. A typicalenhanced NMR signal is shown in Fig. 2, from which the target polarization is estimated to be 10 %.

-8-

Fig. 2. Typical enhanced NMR signal averaged by 1000 times sweeps, from which the target polarization
can be estimated to be 10 %.

Fig. 3 shows the typical energy and particle-identified spectra measured by the counter telescope systems at 20 MeV incident deuteron beam, the upper and lower ones of which show the energy spectrum of
deuterons from D(d, d)D scatterings and the protons from D(d, p)T reactions, respectively. The scattereddeuterons and the reaction protons can be identified clearly within 350 KeV (FWHM) energy resolutions
for deuterons, which might be caused mainly from the target thickness of the CD2 foil.
The asymmetries of the deuterons yields from D(d, d)D elastic scattering were obtained with an statistical uncertainty less than 0.1 % from Fig. 3. Then, the target polarization was estimated to be about 10%, which was however not so stable during the test experiment because of the cooling temperature as inhigher than 1 K mainly due to the unstable operation of mixing chamber.

References[1] R.M. Kulsrud et al., Phys. Rev. Lett. 49 (1982) 1248-1251.
[2] H.M. Hofmann and D.Fick, Phys. Rev. Lett. 52 (1984) 2038.
[3] J.S. Zhang, K.F. Liu, and G.W Shuy, Phys. Rev. Lett 57 (1986) 1410; 55 (1985) 1649.
[4] J.S. Zhang et al., Phys. Rev. C 60 (1999) 054614.
[5] Y. Tagishi, J. Sanada, Nucl. Inst. and Meth. 164 (1979) 411.
[6] W.de.Boer, CERN, yellow report 74-11 (1974).
[7] N. Takabayashial, Genshikaku-kenkyu. Vol.43 (1997) 1-43.

-9-

Countsa) deuteron spectrumoθlab. = 32.5

D(d,d)D

9000
8000
7000
6000
5000
4000
3000
2000
1000
0
150

175

200

225

250

3000

275

300

325

350

b) proton spectrumoθlab. = 32.5

2500

D(d,p)T

2000
1500
1000
500
0
150

175

200

225

250

275

Energy (Arb. unit)

300

325

350

Fig. 3. Typical energy spectra after particle identifications of deuterons (a) and protons (b) obtained by aleft-hand side counter telescope at 32.5 degree lab. angle. Hatched peaks in (a) and (b) are identified as D(d, d)D elastic scattering and D(d, p)Treaction, respectively, from kinematical analyses.

- 10 -

2.1

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

M.Iijima, Y.Aoki, N.Okumura, H.Ishiguro, S.Igarashi, T.Ishikawa, M.Yamaguchi and Y.Tagishi
In the 1930s Lawrence and coworkers [1] measured deuteron induced γ ray activity and found that theenergy dependence of (d,p) reaction yield was significantly weaker than that of Gamow’s theoretical value
at around Ed = 2 MeV. Oppenheimer and Phillips [2] explained that this weak energy dependence is dueto the Coulomb break-up effect arising from small binding energy of deuteron. Later in the 1990s Bencze
and Chandler [3] reported this effect was small and negligible.
We thought this problem is not resolved yet and started an experiment to elucidate the Coulomb
stripping. In the experiment our aim is to measure energy dependence of the ratio of proton yield from118 Sn(d,p)119 Sn(g.s.)reaction to that of elastic deuteron. The target was nat Sn of 756 µ g/cm2 thick.

Detectors were two E-∆ E counters, each of which was comprised of two identical SSD’s with 28 × 28
mm2 active areas. Solid angles of the detectors were 39 and 60 msr. We used 7.5 MeV deuteron beamfrom the Pelletron at UTTAC. Beam current on the target was of the order of 1 nA.
Fig.1. shows the spectrum of deuterons and protons from the d + nat Sn system observed at 150◦ . The
peaks were assigned from the knowledges of kinematic relationship of (d,p) reaction, isotopic abundance
and angular momentum conservation. Fig.2. shows the experimental and the theoretical differential crosssections for 118 Sn(d,p)119 Sn(g.s.) reaction. Error bars in the figure are from counting statistics. The
theoretical values are calculated with DWUCK4 [4] and the optical potential employed is due to Pereyand Perey [5].The theoretical differential cross sections thus obtained are multiplied by the factor of 2.0
to fit 130◦ ∼ 150◦ points. The theoretical and the experimental values do not agree well at 70◦ and 110◦
CM angles.
In the next experiment we are planning to use enriched 118 Sn target and initial deuteron beam of 5 ∼7 MeV to measure the energy dependence of the differential cross sections.

References[1] O.E.Lawrence, E.McMillan and R.L.Thornton, Phys. Rev. 48,493(1935)[2] J.R.Oppenheimer and M.Phillips, Phys. Rev. 48,500(1935)[3] G.Bencze and C.Chandler, Phys. Rev. C53,880(1996)[4] P.D.Kunz, computer program DWUCK4, private communications[5] C.M.Perey and F.G.Perey, Phys. Rev. 132,755(1963)- 11 -

1e+06Sn(d,d0)

100000Counts

10000

120

Sn(d,p0)118

Sn(d,p0)

1000

116

Sn(d,p1)

116

Sn(d,p0)

100

10

1
100

200

300

400

500

600

700

800

900

1000

E+∆E channel

Fig. 1. Energy spectrum of deuterons and protons obtained with 7.5 MeV deuteron beam and nat Sn target;taken at θlab = 150◦ .

3.5
3

σ (mb/sr)

2.5
2
1.5
1
0.5
0
0

20

40

60

80
100
θCM (degree)

120

140

160

180

Fig. 2. Comparison of experimental and DWBA calculation for 118 Sn(d,p) reaction. See text for moredetails.

- 12 -

2.2

Differential cross sections and vector analyzing powers in proton
elastic scattering from 28 Si around neutron threshold energy

N. Okumura, H. Ishiguro, T. Ishikawa, M. Iijima, S. Igarashi and Y. Aoki
Differential cross sections (d σ /dΩ) and vector analyzing powers (Ay ) of proton elastic scatteringfrom nat Si were measured around threshold energy of (p,n) reaction. The target was a SiO2 glass, where
the thickness of nat Si was 0.97 mg/cm2 . Two pairs of E-∆E counter telescope were used and particle
identification was made on CRT two dimensional display.
Figures 1 and 2 show the d σ /dΩ and Ay angular distributions thus obtained, respectively.
25

nat

σEL/σRuth

20

Si+p

15

10

5

0
40

60

80

100
θCM [deg]

120

140

160

Fig. 1. Energy dependence of differential cross sections. Curves correspond from lower to upper to proton
laboratory energy of 15.600, 15.650, 15.750, 15.800 and 15.850 MeV, respectively. Ordinate is theratio to Rutherford cross sections. Except for the lowest curve, all the curves are shifted by 3 unit.

2.5
2
1.5

Ay

1
0.5
0
-0.5
-1
40

60

80

100
θCM [deg]

120

140

160

Fig. 2. Energy dependence of Ay . Except for the lowest curve, all the curves are shifted by 0.4 unit. see
also the comments of fig 1.

As can be seen from these figures, d σ /dΩ and Ay at backward angles at 15.750 MeV behaves somewhat differently from that of the other energy. It seems that the nuclear attraction is stronger at 15.750
MeV than the rest of the data.
The experiment is intended to extract partial wave delay time in this reaction. As was reported in ref. 1,
backward differential cross sections are generally larger than that expected by the global optical potential
parameters. Total reaction cross sections calculated by using the usual optical potential parameters fall in
the range of 800-900 mb, while that of Okumura is about 600-650 mb.
Combining the experimental data measured thus far, extended optical model analysis is underway to- 13 -

extract energy dependence of the phase shift.

References[1] R.De.Leo, G. D’Erasmo, A. Pantaleo, G. Pasquariello, G. Viesti, M. Pignanelli and H. V. Geramb
Phys. Rev. C 21, 646 (1979).

- 14 -

2.3

Measuring energy dependence of proton total reaction cross section
around neutron threshold energy

K. Ishiguro, S. Igarashi, M.Iijima, N. Okumura and Y. Aoki
After measuring energy dependence of total reaction cross section σR of p+nat Si system 1], we planned
to measure that of p+12 C system at around E p = 19.6 MeV. Minor improvement of the experimental setup
was made, which consist of 1) replacing a rotary slit just upstream of a switching magnet to a one withfour independently controllable jaws and 2) moving a beam defining slit of 0.8 mm diameter to about 10
cm upstream of a target. Figs. 1 and 2 show the plan view of the experimental arrangement.
Beam intensity of about 1,000 protons/s on the target was realized as follows, 1) Faint beam wastransferred to the beam stop located about 70 cm upstream of the target. 2) The beam stop was removed
from the beam line after decreasing the field intensity of the switching magnet slightly. 3) By observing
the output of a proportional counter, the filed intensity was gradually recovered carefully. 4) Widths ofthe slit located upstream of the switching magnet was adjusted to keep the count rate of the proportionalcounter as desired level. 5) steps 3) and 4) are repeated until maximum beam is transferred to the target.
6) Fine adjustment of the ion optical devices in the beam line was made by referring the count ratio of the
proportional counter and an active slit just in front of the proportional counter.
Total reaction cross section is measured by a beam attenuation method, i.e., σR is given by the following relation,
1
σR =
nx




I0 − I i0 − i
−
.
I0
i0

Number density n and thickness x of the target appear in the denominator of the right hand side. I0 (I)is a number of protons which hit (passed through ) the target. I0 (I) is counted by a pair of proportionalcounter (plastic scintillator) just in front of (behind) the target. i0 and i correspond to I0 and I with notarget. Details of the counting system, including active slits and counting logic, are given elsewhere 1].
Typical beam loss in the counting system, defined as (i0 − i)/i0 was about 1 − 3 × 10−4 .
Natural carbon foil of 0.1 mm thick was used. Preliminary σR at 19.6 MeV was about 700 mb, which
is about two times larger than the complied values 2]. The reason of the difference is not pinned down yet.

References[1] N.Okumura et al., Nucl. Instru and Meth A 487, 565(2002).
[2] R.F.Carlson et al., Atomic Data and Nuclear Data Tables. 63,93(1996).

- 15 -

Q-Mag. & Steering Mag.

Switching Mag.

Up Stream Active Slit
KOYAMA Chamber
Slit

S.M.-Up Stream Slit

Image Slit

S.M.-Down Stream Slit

15
Target andcounters

A

610 mm

600
700 mmmm

1600 mm

5800 mm

797

mm

2603

mm

Fig. 1. Plan view of beam transport system

Active Slit (4)Gas Counter (2),(3)Active Slit (1)Target
Scintillator (5)Proton Beam

10mm
Fig. 2. Counting system of protons- 16 -

Scattering Chamber
Up Stream Slit

2.4

Analyzing powers for the 6 Li(d,p)7 Li reaction at incident energy of
90 keV

M.Yamaguchi, N.Yoshimaru and Y.Tagishi
We measured analyzing powers Ay , Azz, Axz and Axx−yy for the reaction 6 Li(d, p)7 Li at the incident
energy of 90 keV. At this incident energy the direct reaction component is small enough and the resonant
reaction one is dominant. Moreover, at low incident energies the penetrability of the centrifugal barrier
limits the orbital angular momenta in the incoming channel to a few, low values. In such case, someof resonance are predominant and the analysis in terms of (l, s, J) reaction matrix elements is especiallyindicated. In this paper, we treat the experimental data by this analysis. Such measurements and analysis
were made for the same reaction at the incident energies of 600 and 960 keV by Glor et al.[1]. As theymentioned, their data may include the interference term with the p- and d-wave contribution. Moreover, we
think that the direct reaction component can not be negligible in their case. We measured these analyzing
powers at a lower energy to simplify the analysis and clear the mechanism of this reaction.
The experiment was performed using the Lamb shift type polarization ion source[2] at UTTAC. The
polarization of the deuteron beam was measured by the quench-ratio method[3] just before and after eachrun. The typical value of the beam intensity was about 100 nA and that of the beam polarization was
about 0.7. The uncertainty of the polarization is about 0.02. Fig. 1 shows the placement of the detectors
and the target. The target is a layer of lithium carbonate LiCO3 having the thickness of about 10 µ g/cm2
on an aluminum backing having the thickness of about 15 µ m. The enrichment of 6 LiCO3 is 95 %. The
beam was introduced to the lithium carbonate layer and was intercepted by the aluminum backing, whichplays the role of Faraday cup. A slit with a diameter of 5 mm was placed at the distance of 150 mm
upstream from the target. The energy loss in the layer of lithium carbonate is about 8 keV. A meshed sheet
of SUS supplied with a voltage of −300 V was placed in front of the target to suppress the secondary
emission electron from the target. Because the reaction cross-section is very small, we placed twelve
Si-SSD’s around the target at every 15◦ scattering angles from 0◦ to 165◦ and measured at twelve angles,
simultaneously. Each detector was placed at the distances of 140 mm from the target and has the solid
angle of 10 msr. On the each Si-SSD placed in the range of scattering angle from 90◦ to 165◦ , a mylar
sheet having the thickness of 9 µ m was put in order to block elastic deuterons.
Fig. 2 shows the circuit including the detectors. Each Si-SSD is written as a condenser. Each pairof condensers are divided by a resister. The energy of the detected particle is proportional to the sum of
two currents IA and IB . The active detector is identified by using the value IA /(IA + IB ) or IB /(IA + IB ).
Fig. 4 shows the following block diagram, which mainly consists of NIM modules. The currents IA and
IB is transformed into the proportionable voltages VA and VB by pre-amplifiers, respectively. The spinstate of the polarized beam is controlled by FAst Spin State Interchange Control System (FASSICS). The
information of the spin state is represent by two binary digits, which are included into the main signals VA
and VB , respectively, as bias voltages. We newly build a multi-dimensional data taking system in order toproceed this experiments smoothly. This consists of a PC, two PCI-type ADC-board PCI-3163’s (InterfaceCo.) and some small computer programs. Fig. 3 shows a two dimensional spectrum. The spectrum has- 17 -

four spectrum-regions and each region corresponds to a spin state of the incident beam.

r

1

r

2

r

2

r

2

r

2

r

2

r

1

IA

IB
SI-SSD’s

Fig. 2. The circuit including the detectors.
Each Si-SSD is written as a condenser.
Each pair of condensers are divide bya resister. The energy of the detectedparticle is proportional to the sum of
two currents IA and IB . r1 = 1 kΩ,
r2 = 1.5 kΩ.
Fig. 1. Scattering chamber and the layout of the detectors. Dimension
are given in units of mm.

The incident energy dependence of the direct reaction component was estimated by Czerski et al.[4].
They calculated the angular distributions of the cross section for this reaction at four energies from 145 to
875 keV by using distorted wave Born approximation (DWBA) analysis. They assumed that the resonancecomponent has some isotropic angular distribution and that there is no significant interference effects
between the direct and resonance amplitudes. Consequently, their results well explain those experimental
data. According to their results, the direct component becomes smaller when the incident energy becomes
lower. The component is about 50%, 30% and 13% at the incident energy of 900, 600 and 90 keV,
respectively.
In the following sentences we suppose the direct reaction component is negligible. The expansion of
the analysing powers in terms of Legendre polynomials

σ0N (θ )A j (θ ) = ∑ a j (L)PL,m (cos θ ),

(1)

L=m

where


 0,
m=
1,

2,

for
for
for

j = zzj = y and xz
j = xx − yy(2)results in the expansion coefficients a j (L) given in table 1. Fig. 5 shows the measured analyzing powers
and the results of the analysis in terms of (l, s, J) reaction matrix elements. The solid lines and the dashedlines represent the fitting results and the result supposing that the reaction goes only through a resonant
process (l, s, J π , l  , s) = (0, 2, 2+, 1, 2), respectively. The dashed lines almost explain the experimental
data. This means that the main path of the reaction is (0, 2, 2+, 1, 2). In the case of the coefficients for- 18 -

vector analyzing power, the coefficient ay(1) has large non-zero value. This means that the reaction havethe interference term of the resonance.[5] In the case of the coefficients for tensor analyzing powers,
The coefficients a j (1) and a j (2) have nonzero-values. Figs. 6 show the energy dependences of thesecoefficients a j (1) and a j (2), respectively. These data at the incident energy of 600 and 960 keV are
those of Glor et al.[1] If a resonance excited predominantly by s-wave deuterons, the components of theanalyzing power shows a characteristic angular dependence. As long as the resonant element alone isconsidered, only the coefficient a j (2) for the tensor analyzing power can be nonzero and are subject to therelation[5]azz (2) = 2axz (2) = 2axx−yy (2).

(3)

The comparison of the terms of relation 3 is shown in Fig. 6. The error-bars of our data are larger
than those of the data at the incident energies of 600 and 900 keV, however, as mentioned above, thecontribution of the p- and d-wave and the contribution of the direct reaction are smaller or negligible inthe case of our data. Although the coefficients are subject to the relation (3) at the incident energy of
90 keV, as shown in Fig 6, the coefficients azz (1) and axz (1) has non-zero values. This means that someother resonant element is concerned.
Table 1. Legendre polynomial coefficients a j (L) for the analyzing powers.

L
0
1
2
3
4
5
6

ay (L)−0.127 ± 0.021−0.013 ± 0.018
0.008 ± 0.014−0.002 ± 0.011
0.002 ± 0.010

azz (L)0.051 ± 0.021
0.133 ± 0.033
0.508 ± 0.041−0.091 ± 0.049
0.000 ± 0.053

axz (L)0.113 ± 0.064
0.283 ± 0.052−0.022 ± 0.042−0.000 ± 0.032−0.001 ± 0.030

axx−yy (L)0.317 ± 0.050−0.016 ± 0.030−0.006 ± 0.020
0.006 ± 0.013−0.001 ± 0.009

References[1] M.Glor, H.P.Naegele, G.Morgan, R.Neff, H.Rudin and F.Seiler, Nucl. Phys. A286 (1977) 31-41[2] Y.Tagishi and J.Sanada, Nucl. Instr. and Meth. 164 (1979) 411.
[3] Gerald.G.Ohlsen, J.L.McKibben, G.P.Lawrence, P.W.Keaton, Jr., and D.D.Armstrong, Phys. Rev.
Lett. 27 (1971) 599.
[4] K.Czerski, H.Bucka, P.Heide and T.Makubire, Phys. Rev. Lett. B 307 (1993) 20-24[5] F.Seiler, Nucl. Phys. A187 (1972) 379- 19 -

400

200

200

400

Fig. 3. A two dimensional spectrum.The spectrum has four spectrum-regions and each region corresponds
to a spin state of the incident beam.

POS / NEG (2 / 0V)

FASSICS

ON / OFF (2 / 0V)
PERMIT

VA

FASSICS : FAst Spin State Interchange Control System
PA : Pre Amplifier (ORTEC 142B)
AMP : Amplifier (ORTEC 572)
LG : Linear Gate and Stretcher (ORTEC 542)
SUM : Dual Sum and Invert (ORTEC 433A)
ADC : Analog to Digital Converter (Interface PCI-3151)

UNI

PA

AMP

PA

AMP

VB

LG

SUM

IN 1

LG

SUM

IN 2

POS OUTTRIG

UNI

LL REF IN

SUM

AMP

TSCA
BI

DC INPUT

Fig. 4. Block diagram.

- 20 -ADC PCI port PC

0.05

0.8

Ay

Azz

0.6

0

0.4

-0.05

0.2
-0.1

0

-0.15

-0.2

-0.2

-0.4
0

60

120

180

0

Axz

0.6

60

120

180

Axx-yy

0.6

0.4
0.2

0.4

0
0.2

-0.2
-0.4

0

-0.6
0

60

120

180

0

60

120

180

Fig. 5. Results of the measurement of the analyzing powers. Solid lines represents the fitting results.
Dashed lines are the result supposing that the reaction goes only through a resonant process(l, s, J π , l , s ) = (0, 2, 2+, 1, 2).

0.2

azz(2)
2axz(2)2axx-yy(2)

0.8

aj(2)

0.1
aj(1)

1

azz(1)
axz(1)
ay(1)

0

0.6
0.4

-0.1

0.2

-0.2

0
0

200

400
600
Elab.[keV]

800

1000

0

200

400
600
Elab.[keV]

800

1000

Fig. 6. The left and right figures show the coefficients for the vector and tensor analyzing power, respectively. These data at the incident energy of 600 and 960 keV are those of Glor et al.[1]- 21 -

2.5

Proton-induced reaction for heavy elements

T.Hayakawa1 , T.Shizuma1 , T.Komatsubara, K.Miyakawa
The solar system abundance ratio is a record of stellar nucleosynthesis before the solar system formation. About 99% of elements heavier than the iron group were synthesized by two neutron capture
reaction chains, s- and r-processes. However there are rare neutron-deficient stable isotopes that can beproduced neither s- nor r-processes. They are called to be ”p-nuclei”. Their origin has been discussed withpossible nuclear reactions and astrophysical sites for a long time. The proposed reactions are the β -decay
after the rapid proton capture reactions in novae and X-ray burst in neutron stars[1], photodisintegration
reactions in supernova explosions (γ -process)[2], proton-induced reactions by cosmic rays[3], neutrinoinduced reactions in supernova explosions[4]. A measurement of a cross section of a (γ ,n) reaction using
the real photon has been carried out in viewpoint of the γ -process[5]. The calculated results of the γ process with type II supernova explosions have success to represent partly the solar system abundance ofthe p-nuclei[2, 5]. The calculated results indicated that the Mo and Ru isotopes may have the different
origin from other p-nuclei[2]. Proton capture reactions in low energy region have an important role for the
proton capture process[6]. However no cross sections of the proton capture reactions in a region heavier
than Sn isotopes except a Ce isotope has been measured.
We here carried out a measurement of a decay γ -ray followed by β -decay of Eu isotopes producedby the p+nat Sm reaction in order to evaluate the proton capture cross section of the Sm isotopes. Natural
Sm targets have been irradiated by the proton beam with a energy of 5 MeV. The proton was provided
by the tandem accelerator in University of Tsukuba. Fig. 1 shows a nuclear chart and nucleosynthesis
flow by the proton-induced reactions in an Sm ∼ Gd region. The natural Sm sample consists of sevenstable isotopes, 144,147,148,149,150,152,154Sm. Many unstable Eu isotopes were produced by the reaction in
the present experiment. Almost Eu isotopes have life-lives in order of 1 ∼ 100 days except a few isotopes.
We can measure both the γ -ray transition energies and the half-lives. The target was irradiated for about
1 day. After the irradiation, the γ -rays emitted from the activated samples were measured by a HPGe

detector. Total efficiency of the HPGe detectors is about 40% relative to 3 ×3 NaI detector and theirenergy resolution is about 2.8 keV at 1.3 MeV γ -ray. The efficiency is calibrated with standard sourcesof 152 Eu and 133 Ba. The γ -rays from the samples were measured with a lead-shielded low-backgroundenvironment. We observed the γ -rays from the unstable Eu isotopes. We will measure the changed currentof the proton beam with high accuracy and the intensities of the decay γ -rays to evaluate the total crosssections of the proton-induced reactions.

References[1] H. Schatz et al., Phys. Rev. Lett., 86, 3471(2001).
[2] M. Rayet et al, Astron. Astrophys. 298, 517(1995).
[3] J. Audouze, Astron. Astrophys. 8, 436(1970).
1 Japan Atomic Energy Research Institute, Advanced Photon Research Center, Kyoto, Kizu, Umebidai 8-1- 22 -

150

Gd

155

152

154

156

151

153

4.8y

152

154

1.8 My
13h

Eu

5.9d

Sm

144

4.6d

340d

24d

55d

93d

37y

146

147

148

149

150

90y

0.1Gy

Pm

265d

363d

18y

5.5y

2.6y

2.2d

1.18d

Nd

142

143

144

145

146

148

150

Pr

141

Fig. 1. Nuclear chart and proton-induced reactions around Sm isotopes.

[4] R.D. Hoffman et al., Astrophys. J. 460, 478(1996).
[5] H. Utsunomiya et al., Phys. Rev. C 67, 015807 (2003).
[6] Gy. Gryüky et al., Phys. Rev. C 68, 055803(2003).

- 23 -

3.1

Electron emission induced by fast atom clusters

H. Kudo, T. Suzuki, M. Nagata, T. Shimada, K. Shima, K. Sasa, S. Ishii, Y. Saitoh1 , S. Yamamoto1 ,K. Narumi1 , H. Naramoto1 , and T. Kaneko2
An accelerated cluster ion induces correlated atomic impacts when it is incident on a solid target. This
causes radiation effects different from those induced by impact of a single ion. Actually, fast cluster ionsin the MeV/atom velocity range give rise to nonlinear radiation effects on solid targets with respect to thenumber of atoms in the cluster n. These radiation effects by fast atom clusters have been summarized inrecent reviews [1, 2].
The aim of the UTTAC–JAERI(TIARA) collaboration for study of cluster beam interactions withsurfaces is to investigate the cluster effects by energy analysis of the cluster-induced electrons at low
energies. The collaborating work based on the three accelerators at UTTAC and TIARA would provide
knowledge about the electronic processes in the cluster impact on solid surfaces. Such a basic approach
will also be of fundamental importance for future material processing by fast-cluster impact.
In this fiscal year, the experimental data have been obtained mainly at TIARA, using a new 180◦ spectroscopy system developed at UTTAC using the cluster beams from the UTTAC Tandetron. The beams
of 0.50 MeV/atom, i.e., 41.7 keV/u, C+n (n = 1, 4, 8) were obtained from the 3 MV tandem accelerator at
JAERI-Takasaki. They were incident on the samples of highly-oriented pyrolytic graphite (HOPG) witha cleaved (0001) surface, and chemically cleaned Si. The surface of the Si sample was cut ∼3◦ off fromthe (100) surface so that the ions suffer no channeling effect under incidence in the normal direction of
the surface. The secondary electrons were measured at 180◦ with respect to the beam direction, using a
45◦ parallel-plate electrostatic spectrometer of the double-deflection type, as illustrated in Fig. 1. The
180◦ measurement is advantageous for the purpose of avoiding errors associated with misalignment of
the spectrometer direction. Once the spectrometer is accurately placed at 180◦ , its entrance axis always

Sample holder

1mm aperture

Faraday cup

Beam
-V1
Electron spectrometer(∆E/E=3.3%)

pA
5cm

Figure 1: Schematic diagram illustrating the measurements of cluster-induced electrons. Note that V1 =60 V throughout the experiments.
passes through the irradiated spot on the surface of the sample. This is not necessarily anticipated at
1 JAERI, Takasaki
2 Okayama University of Science- 24 -

other detection angles. In some cases, the misalignment is caused by different beam-transport conditions
for different cluster beams, which effectively changes the counting efficiency, and therefore, disturbs themeasurements of n–dependence of the electron spectra.
The solid targets were negatively biased i.e., V1 = 60 V, to obtain high transmission of the electrons
in the spectrometer, especially at energies lower than 50 eV. In this case, the origin of the energy spectrais shifted to the higher energy side by ∼eV1 , where e is the electronic charge. It follows that the energy
spectrum of the electrons emitted from the target is separated effectively from the background signals dueto the stray electrons at ∼0 energy, as seen in Fig. 2. In this case, the real origin of the energy axis is
assigned to be 52 eV which is the threshold energy for appearance of the electron signals of interest. Furthermore, to enhance the counting efficiency, +200 V was applied to the entrance of the electron multiplierfor pre-acceleration of the electrons. In the present measurements, the relative energy resolution of thespectrometer is given by ∆E/(E + eV1 ) = 3%, for example, ∆E = 2.1 eV at E = 10 eV.
106
C1+ on Al

Yield (counts)

105∆Ε/Ε = 3%

Effective shift
=52eV

104
103
102
10
1

0

20

40

60

80

100 120 140 160

Electron energy (eV)Figure 2: Energy spectra of electrons emitted from Al bombarded by 0.50 MeV C+
1 for 60 V acceleration(V1 = 60 V). The real zero energy is assigned to be 52 eV, the threshold energy for counting the signals ofinterest. The relative energy resolution of the spectrometer is ∼3%.
The cluster beam current was adjusted in the range 3–10 pA, depending on the ion species, and stabilized typically within ±4%, Also, it was often monitored by the Faraday cup, shown in Fig. 1, which
can be used with moving the sample holder out of the beam path. Since the beam current of the clusters
was unable to correspond directly with the measured target current, the plate voltage of the spectrometer
was applied stepwise typically per 1 sec. This allows to obtain the electron spectra normalized to the same
number of the incident atoms, as are necessary for the present study.
The beam dose required for accumulating the spectrum was in the range 5×109 to 2×1010 projectiles/cm 2.
The experiments were carried out at room temperature under a pressure of ∼6×10−6 Pa. Under the present
vacuum conditions, possible existence of contaminant atoms on the surfaces is anticipated. This shouldslightly change the transmission of outgoing electrons across the surface, but should not affect the n dependence of the electron energy spectra, which is of primary interest in the present studies.
The energy spectra of electrons presented here are raw data, i.e., the yield in the vertical axis is- 25 -

the number of electron signals counted. Accordingly, the spectra include no correction for the energy
acceptance of the spectrometer, nor for the energy dependence of the efficiency of the electron multiplier.
This is of minor importance because the measured electron yields for different experimental conditions
are compared always at the same electron energy. Furthermore, the energy axes of the spectra represent
the real values, as noted earlier.
40000

40000
+

0.5 MeV/atom Cn+ on Si

0.5 MeV/atom Cn on HOPG
30000

20000

10000

n=8
0

0
25

10

n=1

20000

n=4

20

30

Relative yield (counts)

Relative yield (counts)

30000

n=1

10000

20

n=4
n=8

0

0

10

20

30

25
20

C K-Auger

15

15

10

10

5

5

0
140 160 180 200 220 240 260 280 300

0140 160 180 200 220 240 260 280 300

Electron energy (eV)Electron energy (eV)Figure 3: Energy spectra of electrons emitted from HOPG (left) and Si (right) bombarded by
0.50 MeV/atom C+n (n = 1, 4, 8). The yields are shown for the same number of the incident C atoms.
Figure 3 shows the energy spectra of electrons emitted from HOPG and Si, bombarded by 0.50 MeV/atomC+n (n = 1, 4, 8). The yields for the two targets are shown for the same number of the incident C atoms
for comparison of the spectra per projectile atom. The carbon K-shell Auger peak originating from the
HOPG target can be seen at the expected energy of 260–270 eV, demonstrating the validity of the rescaledenergy axis. Also, the absence of the carbon K-shell Auger peak for Si target assures reasonable surface
conditions. It should be noted that in this case the K-shell ionization cross section is 8 × 10−18 cm2 , and ismainly due to the molecular-orbital promotion of a carbon K–shell electron [3], in contrast to the production process of low-energy electrons of interest resulting mainly from the direct ionization of outer-shelland velence electrons in the target. Also, the Auger electrons emitted from the projectile carbon atoms
in the direction of 180◦ should have an energy of ∼130 eV, however, the correspoding peak was hardly
recongnized in the spectra.
In Fig. 3, the yield at low energies is appreciably reduced with increasing n. Details of such nonlinear+
character can be seen in Fig. 4, where the ratios of the spectra for C+n (n = 4, 8) to C1 are shown. The ratios

take minimum values near the zero energy, for example, ∼0.50 for large clusters, increase with increasing
the electron energy, and become ∼1 at 100–200 eV. The estimated minimum values are indicated by the- 26 -

1.2

1.2
0.5 MeV/atom Cn+ on HOPG

0.5 MeV/atom Cn+ on Si
1.0

C4+ / C1+

0.8
0.6

Yield ratio

Yield ratio

1.0

C 8+ / C 1+

0.6
C 8+ / C 1+

0.4

0.4

0.2

0.2

0

0

10

20

30

40

C 4+ / C 1+

0.8

50

Electron energy (eV)

0

0

10

20

30

40

50

Electron energy (eV)Figure 4: Ratios of spectra for HOPG (left) and Si (right) bombarded by 0.50 MeV/atom C+n (n = 1, 4, 8).
The dashed lines show the estimated minimum values of the ratios.
dashed lines in Fig. 4. Such pronounced reduction of the electron yield can be hardly explained in termsof the stopping power, for which the predicted cluster effect is as small as less than 5% [7].
The yield ratios at zero electron energy R0 , shown by dashed lines in Fig. 4 are effectively independentof the target material. This indicates that R0 stems from the charge states of the ions near the surface since
the charge states of ions in solid is only weakly dependent on the target material [5]. The electrons of nearzero energy should be produced by distant collisions with the clusters so that we may apply the conceptof the effective point charge to the electron emission [6]. Actually, the interaction of an n–atom clusterwith the target electrons is written in terms of the effective charge Qn . From the charge dependence of theRutherford cross section, R0 is given by
R0 = (Qn /Q1 )2 ,(1)

where Q1 for the C+
1 impact can be assumed to be 1.0 near the surface since the input charge state should
remain almost unchanged near the surface, considering that the equilibrium charge of 0.5 MeV/atom C is
1.4, [5, 7] which is close to the input charge state. From the experimental data, the values of Q determined
are Q4 = 0.83 ± 0.03 and Q8 = 0.69 ± 0.03. Such reduction of the effective charges is consistent roughlywith the observations of charge states of transmitted cluster fractions by Brunelle et al. This also implies
reduction of charging effect when atom clusters are incident on insulators. Further studies with heavier
atom clusters are now under way.

References[1] D. Jacquet, Y. Le Beyec, Nucl. Instrum. Methods B 193 (2002) 227.
[2] E. Parilis, Nucl. Instrum. Methods B 193 (2002) 240.
[3] R. C. Der, R. J. Fortner, T. M. Kavanagh, J. M. Khan, Phys. Rev. A 4 (1971) 556.

- 27 -

[4] A. Brunelle, S. Della-Negra, J. Depauw, D. Jaquet, Y. Le Beyec, and M. Pautrat, Phys. Rev. A 59
(1999) 4456.
[5] K. Shima, T. Mikumo, H. Tawara, At. Data Nucl. Data Tables 34 (1986) 357.
[6] N. Stolterfoht, R. D. DuBois, R. D. Rivarola, Electron Emission in Heavy Ion–Atom Collisions(Springer, Berlin, Heidelberg, 1997).
[7] T. Kaneko, Phys. Rev. A66 (2002) 052901.

- 28 -

3.2

Resonant coherent excitation of C5+ observed with loss electron yieldfrom a Si crystal

M. Nagata, T. Suzuki, T. Shimada, and H. Kudo
An axially channeled ion moving along an equally spaced row of atoms experiences a periodic electronic field of frequency v/d, where v is the ion velocity and d is the atomic spacing. A fast ion canthen be excited resonantly when the frequency matches the excitation energy of the bound electron I, i.e.,
I = Nhv/d, where h is the Planck constant and N = 1, 2, 3, · · · [1]. This phenomenon, resonant coherent
excitation (RCE), occurs also for planar channeling. Details of RCE have been described, for example,
in a review by Krause and Datz [2]. RCE has so far been observed mainly by charge-state analysis ofchanneled ions passed through thin, self-supported crystals. RCE also affects the photon emission, or
the convoy electron emission. It should be noted that RCE has been observed under surface channelingconditions.
Recently, Kudo and coworkers have demonstrated that the loss electron yield resulting from the ionizedelectrons from the projectile C ions reflects the charge states of the ions moving along a channeling or
random (nonchanneling) direction [3]. Under RCE conditions, the loss electron yield might be increasedby the easier ionization from an excited state than from the ground state. This is actually a two-steploss process in contrast to the normal (non-resonant) loss process [4]. From a viewpoint of ion-induced
electron spectroscopy, it is of essential interest to investigate the influence of RCE on the production ofloss electron yield from a bulk target since, unless it is negligibly small, it must be taken into accountwhen crystalline targets are used.
The 3.02 and 3.30 MeV/u C5+ and C6+ beams obtained from the tandem accelerator at the Universityof Tsukuba were incident on a chemically cleaned Si(100) surface at room temperature under a pressureof ∼1×10−6 Pa. For Si100, the RCE condition for N = 2 (2nd harmonics) from the ground state to
the first excited state (n = 1 to 2) of C5+ is satisfied at 3.02 MeV/u, while the 3.30 MeV/u energy waschosen to obtain the off-RCE data for comparison with the 3.02 MeV/u data. The beams were collimatedby double slits to an angular divergence of less than 0.015◦ which is much less than the channeling criticalangle of Si100 , ∼0.16◦ . The 100 perpendicular to the Si surface was chosen to observe RCE. Theenergy spectra of the ion-induced electrons were measured at 180◦ with respect to the beam direction overa solid angle of ∼ 2 × 10−3 sr, adopting the experimental setup similar to the previous studies. The relative
energy resolution (∆E/E) of the spectrometer was ∼5%, which is sufficient for the present analysis of theloss electron yield. Further technical details of the 180◦ electron spectroscopy combined with the ionchanneling technique have been discussed in a recent literature [5].
Figure 1 shows energy spectra of the emitted electrons induced by 3.02 and 3.30 MeV/u C5+ and C6+
under Si100, (110), and random incidence conditions. The spectra are normalized to the same numberof the incident ions. The peaks near 1.5 keV is due to Si K-shell Auger electrons. Note that the yield in
the vertical axis is the number of electron signals counted. Accordingly, the spectra include no correctionof the energy acceptance of the spectrometer, nor for the energy dependence of the counting efficiency ofthe electron multiplier. However, this does not affect the discussion below since the electron spectra are- 29 -

compared essentially at the same electron energy. In Fig. 1, EL indicates the loss-peak energy which is the

14000(a) 3.02 MeV/u C on Si (<100> RCE)
C5+
C6+

12000

Random
10000(110)

Relative yield (counts)

8000
<100>

6000

EL
4000
(b) 3.30 MeV/u C on Si (off-RCE)
12000

C5+
C6+

10000

Random

8000

(110)

6000
<100>
4000
EL
2000
0.5

1.0

1.5

2.0

Electron energy (keV)

Figure 1: Energy spectra of electrons emitted from Si bombarded by (a) 3.02 and (b) 3.30 MeV/u C5+ andC6+ under 100 axial, (110) planar, and random incidence conditions. The yields are normalized to thesame number of the incident ions. EL indicates the loss-peak energy. The relative energy resolution of thespectrometer is ∼5%.
kinetic energy of the electron moving at the same velocity as of the ion. The ionized electrons from theion contribute to the backward electron yield at energies lower than ∼EL . We see that the electron yields
for 100 and (110) are reduced, compared with the random case, because of the effective shadowing of
the crystal atoms. It is recognizable that for (110) and random cases the C5+ yield below EL is higher thanfor C6+ , irrespective of the two ion energies. This is due to the collision-induced loss electrons anticipated
not for C6+ , but for C5+ . For 100, in contrast, the loss electron yield can be seen for the 3.02 MeV/uions, while it is hardly seen for the 3.30 MeV/u ions. For a better statistics, we have integrated the electron
yield in the range 0.8–1.4 keV, Yint (C5,6+ ), and the normalized loss yield L has been defined by
L = [Yint (C5+ ) −Yint (C6+ )]/Yint(C6+ ) .

(1)

L is the ratio of the loss yield to the binary-encounter yield. The latter is the dominant energy-transfer
process to the target electrons, as is typical for keV electron yield induced by MeV/u ions. Therefore, L is

- 30 -

Table 1: Values of the normalized loss yield L obtained for the incident energy of 3.02 MeV/u (100 RCE)
and 3.30 MeV/u (off-RCE).
Orientation

3.02 MeV/u

3.30 MeV/u

100 axis(110) planerandom

0.075 ± 0.003
0.055 ± 0.003
0.069 ± 0.003

0.033 ± 0.002
0.064 ± 0.003
0.071 ± 0.003

a measure of production efficiency for the loss electron yield. The values of L obtained are summarizedin Table 1, where the estimated uncertainty in the values arises mainly from the instability of the incident
beam.
In Table 1, we see that under the RCE condition (3.02 MeV/u) the values of L for 100 is enhanced
by a factor of 2.3 relative to the off-RCE case, while neither (110) nor random incidence causes suchenhancement. It is notable that the off-RCE data is consistent with the previous study of loss electrons
also under off-RCE conditions [3], which concludes that the main charge states of 2.5 and 3.5 MeV/u C
ions are C5+ and C6+ for Si100 and random cases, respectively. Indeed, the value of 0.075 for 100 isroughly the same as 0.069 and 0.071 for the random cases, indicating that most of the C5+ are ionized by
RCE.
Since EL is the most probable energy of the produced loss electrons, the typical loss yield for 100
at an energy of ε =1.25 keV in Fig. 1(a) comes roughly from the depth of (EL − ε )/Se, where Se is theelectron stopping power. Using the value of Se = 1.6 eV, the depth, i.e., the escape length is 244 Å. Thisimplies that the observed RCE results typically from 244/5.43  45 glancing collisions with Si atoms.
According to the observation of C5+ RCE by charge state analysis by the Oak Ridge group, the Stark
split of the RCE spectra is relatively small, which is consistent with the present observation of the RCE
enhancement at the calculated resonance energy without considering the Stark effect.
The loss electron analysis is sensitive to the charge states of ions in a crystal. This is contrast to
the case of charge state analysis of ions passing through a thin crystal, or reflected from a crystal surface.
Accordingly, the present study would provide a unique observation technique of RCE. Further experiments
are planned to obtain more refined data.

References[1] V. V. Okorokov, Zh. Ehksp. Theor. Fiz. Pis. Red. 2 (1965) 175 [JETF Lett. 2 (1965) 111].
[2] H. F. Krause, S. Datz, Adv. At. Mol. Opt. Phys. 37 (1996) 139.
[3] H. Kudo, K. Takeda, T. Suguri, W. Iwazaki, C. Sakurai, I. Arano, S. Numazawa, S. Seki, Nucl.
Instrum. and Methods B207 (2003) 283.
[4] N. Stolterfoht, R. D. DuBois, R. D. Rivarola, Electron Emission in Heavy Ion–Atom Collisions(Springer, Berlin, Heidelberg, 1997), Sect. 6.4.
[5] H. Kudo, Ion-Induced Electron Emission from Crystalline Solids (Springer Tracts in Modern Physics
Vol. 175, Springer, Berlin, Heidelberg, 2002), Chap. 5.

- 31 -

3.3

Solid target thickness where energetic ions attain charge equilibrium

K.Shima and K.Sasa
The knowledge on the charge equilibrium thickness, Teq, where projectile charge states attain equilibrium in matter isimportant in the fields of accelerator or nuclear instrument technology. Actually, in the tandem accelerator energy region,
there has been little way to estimate the Teq values [1, 2]. It is because reported data of charge distributions of ionsobserved at charge nonequilibrium region are limited, in addition to the fact that the estimation of Teq from collision process,is not an easy task. In order to serve as a milestone for the systematic understanding of Teq in matter, Teq values have been
investigated for the collision of various ions of Z1 (projectile atomic number) on carbon foils because existing data of Teq
are mostly reported for carbon foils. Our method of approaching the object is on one hand to measure the Teq values byourselves, and on the other hand to accumulate the data by others.
Our data taking for ionic charge distributions in charge nonequilibrium to equilibrium region has been done by usinga magnetic spectrograph, ESP-90. Ion species is Z1=1 to 53, and ion energy region is mostly from 0.5 to a few MeV/u.
A conventional way of expressing the Teq values has been to choose the coordinates of Teq versus ionic energy inunits of MeV/u. [1, 2]. At present, as a result of accumulating much more data, the adoption of these coordinates proved
to be of no use since data points scatter at random. In Fig.1, the Teq values of compiled data at present are plotted as afunction of Z1 for the group of ions with 1, 2 and 6 MeV/u. Some Teq values in the figure are interpolated ones because they
were not taken at exact values of 1, 2 or 6 MeV/u. Fig.1 clearly indicates some structure between Teq versus Z1, which is
caused by the variation of ionic shell where the electron of the most probable charge state in equilibrium is included.
Fig.1. Charge equilibrium thickness Teq of various ions with atomic number Z1 passing through a carbon foil at
projectile energies of 1, 2 and 6 MeV/u.

1000

Z 1 +C
6 MeV/u

2 MeV/ueq

2

T [ug/cm ]100

1 MeV/u
10

1

1

10

Projectile atomic number Z

100
1

References[1] V.P.Zaikov, E.A.Kral’kina, N.F.Vorobjev, I.S.Dmitriev, V.S.Nikolaev and Ya.A.Teplova,
Nucl. Instrum. Methods B5 (1984) 10.
[2] E.Baron, IEEE Trans. NS-26 (1979) 2411.

- 32 -

3.4

Structural characterization of thin films by RBS technique

H. Yanagihara, A. Hatanaka, J. Sawahata, E. Kita, K. Akimoto and H. Kudo
Rutherford backscattering spectrometry (RBS) technique is a powerful and common method to characterize thin film structures. An RBS gives the chemical composition as a function of depth in the sample
and either density or thickness of the analyzed thin film. The other advantages of this technique are: (a)non-distractive , (b) high-sensitive, (c) rapid. Combining with other complementary structure-analysis
techniques such as AFM, STM, SEM, XRD, XAFS and so on, we used RBS experiment to determine
precise structures of various thin films; metal , oxide, nitride, silicide, and nano-particle films prepared bydifferent kinds of growth techniques.
An experimental setups are as follows. 1.5 MeV accelerated 4 He ions with a tandem accelerator placedat the TAC were chosen for regular RBS experiments. The geometry of incident angle(α ), exit angle(β )and scattering angle(θ ) are 30, 0 and 150 degrees, respectively. We used a solid-state detector placed
at 70 mm from the sample surface. The RBS data were analyzed by a commercial simulation program(SIMNRA ver. 5.0[1]) which works on Windows based PCs. This program has functions of both the RBS
data fitting and the spectrum simulation with graphical interfaces.
As an example, an RBS data of a chromium dioxide(CrO2 ) thin film is shown in Figure 1. The
epitaxial CrO2 films were grown on rutile(TiO 2 ) substrates by using a chemical vapor deposition(CVD)method[2]. The thickness of CrO2 is estimated as ∼ 400 Åby assuming the bulk density. Our CVD
system is not equipped a growth-rate control system such as thickness monitor or flow-meter. Therefore
some characterization technique of the film thickness without destruction is necessary. For this purpose,
the RBS is very suitable and essential for our experiments. Other than CrO2 , we examined the similar
analysis for Fe3 O4 , TiN, and GaRN (R denotes rare-earth metals) thin films to find their thickness and/or
chemical composition.
In summary, employing the RBS equipment placed at the TAC, we have performed the structuralcharacterization of various thin films. An useful RBS program made the spectrum analysis easier andquantitatively helped to determine either the film thickness and/or the composition.

References[1] http://www.rzg.mpg.de/∼mam .
[2] S. Ishibashi, T. Namikawa, and M. Satou, Jpn. J. Apl. Phys., 17, 249(1978).

- 33 -

Energy [keV]
100

200

300

400

500

600

700

800

900

1000

1100

1200

4,800

CrO2.dat
Simulated
O
Ti
Cr

4,600
4,400
4,200
4,000
3,800
3,600
3,400
3,200

Counts

3,000
2,800
2,600
2,400
2,200
2,000
1,800
1,600
1,400
1,200
1,000
800
600
400
200
0
0

20

40

60

80

100

120

140

160

180

200

220

240

260

280

300

320

340

360

380

400

ChannelFig. 1. RBS spectrum of CrO2 (001) epitaxial film. The simulation curves for total profile as well as eachelement are displayed.

- 34 -

3.5

Molecular beam epitaxy of Si-based ternary alloy semiconductor
Ba1-xSrxSi2 on Si(111) substrates

T.Suemasu, Y.Inomata, Y.Izawa and F.Hasegawa
Semiconducting iron disilicide (β-FeSi2) consists of abundant Si and Fe, and it has been
attracting considerable attention as a promising material for Si-based optoelectronic devices. From theviewpoint of device application, it is desirable to exploit the so-called band-gap-engineering technique in
β-FeSi2 as in III-V and II-VI compound semiconductors; that is, the modification of the band gap of
β-FeSi2 by replacing some Si atoms with isoelectric C or Ge atoms [1-3]. However, it has been difficult toincorporate notable amounts of C or Ge in β-FeSi2. It is therefore necessary to find anothersemiconducting silicide which is more suitable for forming ternary or quaternary alloys. We think thatorthorhombic barium disilicide (BaSi2) is a good candidate for such a material.
The band gap of BaSi2 is reported to be 1.1−1.3 eV [4-6]. Very recently, we have realized theepitaxial growth of BaSi2 films on Si(111) substrates by MBE (MBE; codeposition of Ba and Si on aheated substrate) using an RDE-grown BaSi2 layer as a template [7]. As far as BaSi2-based ternary alloys
are concerned, there has been only one report on the growth of BaSrSi2 polycrystalline bulk to ourknowledge [8]. The formation of Ba1-xSrxSi2 bulk with Sr molar fractions up to approximately 70 % wasreported. The paper was however focused on the phase transition of Ba1-xSrxSi2 under high pressure andhigh temperature conditions, and thus, there were no descriptions on its electrical and optical properties.
To use Ba1-xSrxSi2 in real devices, it is necessary to form high-quality Ba1-xSrxSi2 films and investigate its
electrical and optical properties. However, there has been no report on the formation of Ba1-xSrxSi2 films.
The purpose of this study is to form Ba1-xSrxSi2 epitaxial films on Si(111) by MBE andinvestigate whether a certain kind of lattice contract takes place by adding Sr into BaSi2.
MBE growth was performed as follows: First, the deposition rate of Ba was fixed at 1.0 nm/min;then a 20-nm-thick BaSi2 epitaxial film was grown at 500ºC for 20 min by RDE, and this film was used asa template to control the crystal orientation of BaSi2 over layers. Next, Ba, Sr and Si were coevaporated on
the BaSi2 template at 600ºC. The deposition rates of Ba and Si were fixed at 1.0 and 0.66 nm/min,
respectively, so that the stoichiometry of BaSi2 was satisfied. The deposition rate of Sr was changed from0 to 2.5 nm/min, and we prepared six samples with different deposited Sr-to-Ba ratios (Sr/Ba ratios)
varying from 0 to 2.5. The temperatures of Ba and Sr K-cells were set at 440ºC and 275−365ºC,
respectively. The total thickness including the template layer was about 80 nm. We chose 600ºC as thegrowth temperature because this temperature was found to be optimum for the epitaxial growth of BaSi2
by MBE [7]. The Sr molar fraction x against Ba in Ba1-xSrxSi2 was evaluated by Rutherford backscattering
spectroscopy (RBS) measurements using C+ ions accelerated at 1.82 MeV. The crystal quality of
Ba1-xSrxSi2 and its a-axis lattice constant were characterized by X-ray diffraction (XRD) measurements
using Cu K α radiation, and the surface morphology was observed by atomic force microscopy (AFM).
Figure 1 shows the RBS random spectra for samples grown with different deposited Sr/Ba ratios.
As seen in Fig.1, with increasing deposited Sr/Ba ratio, the peak corresponding to Sr became clear. These- 35 -

spectra obtained experimentally were reproduced by simulation and the Sr molar fraction to Ba in
Ba1-xSrxSi2 was then derived. There was no difference in Si content between the grown Ba1-xSrxSi2 layerswith different x values. The root mean square (RMS) roughness of the grown films was evaluated by AFM.
They are summarized in Table 1. Surface roughness gradually decreased with increasing x. The reason forthis improvement is not clear at present, but is thought as follows: The amount of deposited Ba wasinsufficient because of Ba desorption from the Si(111) surface due to its large vapor pressure even when
Ba and Si were supplied in stoichiometric proportion. With increasing x, the Sr deposition rate increased
and then the deposited Ba plus Sr ratio to Si could lead to a real stoichiometric condition. Next, the Sr
molar fraction x of Ba1-xSrxSi2 was discussed. It was found that x increased up to 0.49 with increasing
deposited Sr/Ba ratio to 2.5. The x value of 0.49 is smaller than that obtained in Ba1-xSrxSi2 bulk, where
about 70 % of Ba was replaced by Sr.21) It might be possible to incorporate more Sr atoms in the Ba site of
BaSi2 by further increasing the deposited Sr/Ba ratio and by lowering the growth temperature.
To investigate the crystalline quality of the grown layers, θ-2θ XRD measurements were
performed, as shown in Fig. 2. The diffraction peaks of Si(222), BaSi2(400) and BaSi2(600) planes areclearly observed for the samples with x<0.08. On the other hand, the diffraction peaks of BaSi2(400) andBaSi2(600) planes split into two peaks for the samples with x≥0.27. Since the peak positions of the
low-angle diffraction peaks seen around 41° and 65° for these samples did not change at all with x, as
indicated by dotted lines, it can be said that they correspond to BaSi2(400) and BaSi2(600) planes,
respectively. All the samples contained a 20-nm-thick [100]-oriented BaSi2 template layer, and thus, theorigin of these low-angle diffraction peaks is thought to be the BaSi2 template layer. In contrast, thehigh-angle diffraction peaks shifted clearly to a high-angle-region with increasing x, indicating that the
spacing between [100]-oriented planes of the film decreases. The atomic radius of Sr is smaller than thatof Ba, and thus, when some Ba atoms in the BaSi2 lattice structure are replaced by Sr atoms, this kind oflattice contract will take place. The high-angle diffraction peaks are therefore thought to be those of
Ba1-xSrxSi2(400) and Ba1-xSrxSi2(600) planes. On the basis of these results and the fact that there is no
indication of the formation of any secondary phases from the XRD measurements, it can be said that[100]-oriented Ba1-xSrxSi2 films were grown epitaxially on Si(111). For the sample with x=0.08, thediffraction peaks of BaSi2 and Ba1-xSrxSi2 overlap due to the small incorporation of Sr, and thus, a small
peak shift rather than two-peak splitting was observed.
Next, to investigate the lattice contract caused by Sr incorporation into BaSi2, the a-axis lattice
constant of Ba1-xSrxSi2 was evaluated from the XRD peak positions of BaSi2(400) and BaSi2(600)diffraction patterns. Figure 3 shows the Sr molar fraction versus a-axis lattice constant plots for Ba1-xSrxSi2
obtained in this study (+) and in a previous study (●) [8]. To reduce the measurement error, a-axis lattice
constants determined from Ba1-xSrxSi2(400) and Ba1-xSrxSi2(600) peak positions were first plotted againstcotθ after canceling zero offset error by adjusting the measured peak position of Si with the theoreticalone. The peak positions were determined by Gaussian fitting. The lattice constant a of Ba1-xSrxSi2 was thenextrapolated from the intersection of the straight line passing through the above two points at cotθ=0. As
shown in Fig. 3, the lattice constant a of Ba1-xSrxSi2 linearly decreased with increasing x as
a=0.891-0.041x (nm), showing that it follows Vegard’s law. The a-axis lattice constant of the sample with- 36 -

x=0.49 is about 2 % smaller than that of strain-free BaSi2 bulk. However, the gradient of the straight line
obtained in this study is slightly different from that reported in the Ba1-xSrxSi2 bulk. This is probably
because the measured a-axis lattice constants of thin films derived from XRD peak positions were
scattered due to the residual strain in the Ba1-xSrxSi2 layers, and thus, this strain effect should be correctedusing elastic constants of BaSi2. Unfortunately, those values have not been well studied in BaSi2. As far as
the electrical properties of Ba1-xSrxSi2 films are concerned, it was found from Hall measurements that
Ba1-xSrxSi2 is a semiconductor. The details of these measurements will be reported elsewhere.
In summary, we have grown [100]-oriented Ba1-xSrxSi2 epitaxial films on Si(111) substrates by
MBE at 600 oC using a [100]-oriented BaSi2 epitaxial template formed by RDE. RBS measurements
revealed that the Sr molar fraction x of the grown Ba1-xSrxSi2 films was found to be vary from 0 to 0.49 bychanging the deposited Sr/Ba ratio from 0 to 2.5. The a-axis lattice constant of Ba1-xSrxSi2 showed a linear
dependence of the Sr molar fraction x, and the lattice constant a of Ba0.51Sr0.49Si2 was about 2 % smaller
than that of strain-free BaSi2 bulk.
We would like to thank Professor H. Kudo and Assistant Professor H. Yanagihara for their help
with RBS measurements performed at the Tandem Accelerator Center of the University of Tsukuba.
References[1]

H. Chen, P. Han, X. D. Huang, L. Q. Hu, Y. Shi and Y. D. Zheng: Appl. Phys. Lett. 69 (1996) 1912.

[2]

A. Zenkevich, P. I. Gaiduk, H. P. Gunnlaugsson and G. Weyer: Appl. Phys. Lett. 81 (2002) 904.

[3] X. Li, D. Nie and C.Dong: Nucl. Instrum. Methods Phys. Res. B 194 (2002) 47.
[4] J.Evers and A. Weiss: Mater. Res. Bull. 9 (1974) 549.
[5] T. Nakamura, T. Suemasu, K. Takakura and F. Hasegawa: Appl. Phys. Lett. 81 (2002) 1032.
[6] K. Ojima, M. Yoshimura and K. Ueda: Jpn. J. Appl. Phys. 41 (2002) 4965.
[7]

Y. Inomata，T. Nakamura，T. Suemasu and F. Hasegawa: Jpn. J. Appl. Phys. 43 (2004)Ｌ478.

[8] J. Evers: J. Solid State Chem. 32 (1980) 77.

Table I. Deposited Sr/Ba ratio, Sr molar fraction x evaluated by RBS and thickness of a
Ba1-xSrxSi2 film.
SampleDeposited Sr/Ba ratio

Sr molar fraction x RMS
(nm)

A

0

0

7.6

B

0.1

0.03

4.0

C

0.5

0.08

5.8

D

0.8

0.27

2.5

E

1.3

0.41

3.2

F

2.5

0.49

2.2

- 37 -

+

Intensity [arb.units]

1.82 MeV, C

Sr/Ba=0.5

Sr/Ba=0.8
Ba
Si

Sr

Sr/Ba=1.3

100

200

300

400

500

Channel600

Fig.1 RBS random spectra of Ba1-xSrxSi2

Fig.2 θ-2θ XRD patterns of Ba1-xSrxSi2

films grown with different deposited Sr/Ba

films with different x values.

ratios.

a-axis lattice constant [nm]

0.89

0.88

0.87
8

Bulk [ Evers et al. ]+ Thin Film [ This work ]

0.86

0.85
0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Sr molar fraction x [%]Fig.3 Sr molar fraction x dependence of a-axis
lattice constants of Ba1-xSrxSi2 thin films (+)
grown in this work and bulk (●) grown by Evers(ref. 8). The bars show the range ofmeasurement error.

- 38 -

3.6

Swift heavy ions for nano-fabrication of titanium dioxide

Koichi Awazu*1, Yoshihiro Nagasawa,2 Yoshimichi Ohki,2 and Tetsuro Komatsubara
Abstruct
We have developed a nano-micro structure fabrication method in rutile TiO2 single crystal by use ofswift heavy-ion irradiation. The area where ions heavier than Cl ion accelerated with MeV-order highenergy were irradiated was well etched by hydrofluoric acid, by comparison etching was not observed in
the pristine TiO2 single crystal.

Noticed that the irradiated area could be etched to a depth at which theelectronic stopping power of the ion decayed to a value of 6.2keV/nm. We also found that the value of theelectronic stopping power was increased, eventually decreased against depth in TiO2 single crystal with,e.g. 84.5MeV Ca ion. Using such a beam, inside of TiO2 single crystal was selectively etched with 20%
hydrofluoric acid, while the top surface of TiO2 single crystal subjected to irradiation was not etched.
Roughness of the new surface created in the single crystal was within 7nm with the atomic forth
microscopy measurement.

Introduction
Photonic crystal structures for controlling electromagnetic waves in two or three dimensions are applied
for outstanding optical devices.

One of the most conventional methods to obtain micro-structures must

be the reactive ion etching (RIE), however, roughness and ripple pattern on the side wall of
micro-structures, RIE-lag, and etch stop have been frequently observed. Besides the “main stream” ofphotonic crystals’ researches based on semiconductors, photonic crystals based on TiO2 have also beenreported.[1] Micro fabrication techniques for the material have not been established indeed, but thismaterial offers many advantages.

Reflection loss due to connection between photonic crystals and silica

based optical waveguides would be reduced because refractive index values of (2.4(⊥c axis) and 2.7(//)) ina rutile TiO2 single crystal are close to in silica, rather than in semiconductors. Furthermore, opticaltransmission loss of TiO2 is ten times lower than in silicon in the vicinity of 1.5µm as mentioned
previously.[2] Since TiO2 remains high list as a material for the photonic crystals, it is desired to fabricate
a nano-structure with nano-order flatness and precision. In the present work, we examined to fabricate themicro-structure with nano-flatness on both bottoms and side walls in rutile single crystal by swift heavyions. Furthermore, as an unexpected phenomenon, three dimensional structure was created in rutile TiO2
single crystal.
1 CAN-FOR, National Institute of Advanced Industrial Science and Technology, Tsukuba Central 4 305-8562 Japan
2 Department of Electrical Engineering and Bioscience, Waseda University, 3-4-1 Ohkubo, Shinjuku-ku, Tokyo 169-8555, Japan*Corresponding author: k.awazu@aist.go.jp, voice +81-29-861-5650, fax +81-29-861-2919- 39 -

Experimental
The samples used in the present experiment are (100) rutile TiO2 single crystal (purity > 99.99%,
density: 4.25g/cm3) synthesized by the Verneuil flame-fusion method. Ion irradiation using the 12MV
tandem accelerator at Tandem Accelerator Center, University of Tsukuba (UTTAC) was performed atroom temperature. [3]Structural change induced by ion irradiation was investigated by X-ray diffraction(XRD) measurements with a Rigaku FR-MDG apparatus.

A scanning electron microscope (SEM,

Hitachi S-2500CX) and a high-resolution electron microscope (HREM, Hitachi H-9000NAR) were also
employed to observe sample surfaces.

Chemical etching was performed with 20% hydrofluoric acid,hereafter 20% HF, at room temperature.

Results
Figure 1 shows an SEM image of rutile TiO2 (100) single crystal surface subjected to 45MeV Cu ion
irradiation at an accumulated dose of 3.0×1013cm-2 through a 1µm thick gold stencil mask with a 1µm
diameter dot pattern. The irradiated rutile (100) single crystal was then immersed in 20% HF for 40min.
Cylindrical patters with diameter of 1µm with 2µm height were created on TiO2 single crystal. Figure 2
shows XRD spectra of the (100) rutile irradiated by the 84.5-MeV Cu ions. The spectrum (i) is for the
non-irradiated sample. Two peaks at 39.2o and 84.3o, to be assigned to the (200) and (400) planes, areseen. Curves (ii), (iii), (iv), and (v) are the spectra obtained in the samples after irradiation to respective
doses of 1.0 × 1012, 3.0 × 1012, 7.0 × 1012, and 5.0 × 1013 cm-2.
the ion irradiation.

The two XRD peaks become smaller byoBesides them, new peaks appear at 38.3 and 82.5o in spectrum (iii). They become

smaller and move to smaller angles as the irradiation dose increases, and finally disappear in spectrum (v).
Figure 3 shows electronic stopping power Se calculated by SRIM 98 code as a function of the depth
from the sample surface. Values of etched depth were plotted with closed circles in Fig. 3. The point at
Se = 0 was close to the depth where the ion was stopped.

At first glance, the etched depth was shallower

than the depth at Se =0. For instance, the etched depth and the depth at Se =0 for 120MeV I ion were6.5µm and 11µm, respectively. The first order feature was that the values of Se at the etched depth
presented with closed circles were always located around the solid line of 6.2keV/nm irrespective of
incident ions or acceleration energies.

In other words, a threshold electronic stopping power of

6.2keV/nm was apparently necessary to commence etching.
Furthermore, another surprising result was obtained. Namely, after the crystals were irradiated by the
Ca ions with various energies to a dose of 8.0 × 1013 cm-2, they were cut perpendicularly to the surface andimmersed in the HF solution.

Figures 4 show typical cross-sectional SEM images taken for the sample

irradiated by the 72.3, 82.0 and 84.5MeV ions. The position of the irradiated top surface and the
direction of ions are indicated by arrows. The top surface was not etched, while an inside gap or a vacanthollow was created by etching about 4 µm below the surface in case of 72.3MeV Ca ions.

Similar insidegaps were always observed if the energy of Ca ions was higher than 72.3 MeV, and the position of the gap- 40 -

1 µm
Figure 1. A SEM image of the TiO2 surface etched by 20 % hydrofluoric acid for 40min.

The sample

was irradiated with 45MeV Cu ion irradiation to a dose of 3.0×1013 cm-2 through a 1µm thick gold
mask with pattern of 1µm diameter.

(400)

Intensity [a.u.]

(200)
(i)

pristine(ii)

1.0 × 1012cm-2(iii)

3.0 × 1012cm-2(iv)

7.0 × 1012cm-2(v)

5.0 × 1013cm-2

36 37 38 39 40
80 82 84 86
2θ [deg]
Figure 2. XRD spectra of the as-received sample (i), after the 84.5MeV Cu ion irradiation to a dose of
1.0×1012cm-2 (ii), 3.0×1012cm-2 (iii), 7.0×1012cm-2 (iv), and 5.0×1013cm-2 (v).

The peaks at 39.2oand 84.3o

are due to the (200) and (400) planes of the rutile phase, respectively.

became deeper as the energy increased.

For example, when the energy was 82.0 MeV, the gap was seen

at depths between 5.4 to 7.7 µm from the top surface. Figure 3 shows the electronic stopping power Se asa function of the depth. The dotted portion of each curve shows the depths where the hollow etching was
made.

Similar hollow etching was also observed in rutile irradiated by Cl ions with energies of 77.0

MeV and higher to a dose of 1.0 × 1015 cm-2. It was also successful to demonstrate “micro-tunnel” in the
middle of TiO2 single crystal (Figure 5).

An AFM observation of the bottom of the air gap depicted inFig. 4 was shown in Figure 6. Roughness was estimated within 2.5 nm.

- 41 -

120MeV I

S e [keV/nm]

20

50MeV Br
100MeV Ca

10

Se=6.1 [keV/nm]●●

90MeV Cl

0
0

55MeV Si
40MeV I510Depth [ µ m]

15

Figure 3. The electronic stopping power against depth calculated by SRIM98. Closed circles wereexperimental results of etched depth.

82.0MeVCa

72.3 MeV Ca

84.5MeV Ca

top surface
TiO2
air gap
TiO2

5µm
5µm

Figures 4.

5µm

SEM images of the cross section of the sample etched following the (a) 72.3, (b) 82.0, and (c)84.5MeV Ca ion irradiation to a dose of 3.0 × 1014 cm-2.

The ions were irradiated from the top of theimage.

Discussion
In XRD spectra shown in Fig.2, the 84.5-MeV Cu ion irradiation decreased the intensities of the peaks
assigned to the original rutile crystal structure and induced the two peaks at the lower angular side.
According to the Bragg law, a peak shift toward the lower angular side indicated the increase in a lattice
constant. Actually, the expansion was observed as the upheaval by ion irradiation.

Since TiO2 crystal inrutile phase has the largest density among TiO2 polymorphs, it seems that the expansion is due to a
structural change induced by the ion irradiation. Decrease in intensities of both peaks at 39.2o and 84.3omeans the degradation of a crystal structure, i.e. the formation of amorphous phase.

- 42 -

From theseconsiderations, it was found that the ion irradiation induces the amorphous phase and the expansion oflattice in a rutile TiO2 single crystal. The original peak intensity decreased when the ions were irradiatedto a dose of 4.0 × 1012 cm-2 (ii), but the intensity hardly changed with further irradiation (see in (iii) and(iv)). It does not imply the remaining of the crystal structure that the original

1µm

Figure 5. “Micro-tunnel” created by 84.5MeV Ca ion irradiation followed by etching.

20nm

1µm

Figure 6.

An AFM image of a TiO2 surface subjected to 72.3MeV Ca ion irradiation at an accumulated

dose of 8 × 1013 cm-2 through 1µm thick gold mask. Then, chemical etching with 20% hydrofluoric acidwas performed for the irradiated sample.

peaks were still existed after irradiation, because x-ray intensity from Cu Kα was reduced by half through
50µm TiO2 which is deeper than the ion penetration depth. In other words, the undamaged layer below thedamaged layer could be detected by XRD measurement.

- 43 -

Conclusion
We have investigated the structural change in rutile TiO2 single crystal induced by swift heavy-ion
irradiation. It has been clarified that a rutile TiO2 single crystal is not etched by hydrofluoric acid,however, the amorphous region and the stressed lattice region generated by the irradiation of swift heavy
ions can be etched by hydrofluoric acid. When the ion whose value of electronic stopping power was
decreased with depth of rutile TiO2 single crystal and the depth that could be etched was limited to thepoint where the values of electronic stopping power was decayed to 6.2 keV/nm.

It was also found thatwhen the ion whose the maximum value of electronic stopping power was located at inside of TiO2, inside
could be selectively etched keeping the surface rutile phase and we can obtain the hollow structure.
Energy deposited around the path of the ion showed that there was a threshold whether surface etching canbe observed or not.

Since the surface and aspect shape of rutile TiO2 single crystals after etching wasvery flat in the order of nanometer, it was successful to fabricate 3-dimensional nano-structure by use ofthis etching technique.
This methods also makes it possible to fabricate rutile TiO2 plates thinner than a few micron with nanoorder flatness, which has been difficult by the conventional methods. Our method will be available forthe processing of solar cells, photonic catalysts, or photonic crystals, which require nano-fabrication
technique.

Acknowledgement
This work was financially supported by the Budget for Nuclear Research of the Ministry of Education,
Culture, Sports, Science and Technology, based on the screening and counseling by the Atomic Energy
Commission and partly supported by a Grant-in-Aid for Scientific Research from the Ministry of
Education, Culture, Sports, Science and Technology (12450132).

Refereces[1] M. Lanata, M. Cherchi, A. Zappettini, S. M. Pietralunga, and M. Martinelli, Opt. Mat. 17, 11 (2001).
[2] S.Yamazaki, N.Hata, T.Yoshida, H.Oheda, A.Matsuda, H.Okushi, K.Tanaka, J.Physique, 42, C4-297(1981).
[3] K. Awazu, S. Ishii, K. Shima, S. Roorda, and J. L. Brebner, Phys. Rev. B 62, 3689 (2000).

- 44 -

3.7

Absorption of silicon atoms on gold clusters

M.Kubo, T.X.Li and I.Arai
Recently, a novel metal-silicon cluster,i.e.,a close packed silicon cage surrounding a tungstencluster,has been found in the study of the reactions of tungsten clusters with silane[1]. Such a cluster should
be an innovative building block for nanofabrication in the future. So far, both experimental observations[2,3,4,5,6,7,8,9] and theoretical calculations[10,11,12] have been done mainly for a single metalencapsulated silicon cage cluster. However, few experimantal observations[13,14,15] and no theoretical
calculations are available for such a “metal cluster-encapsulated silicon cage” as observed in the recent
study. Therefore, we have not understood even a fundamental process underlying the formation of such anovel metal-silicon cluster at all. We have carried out a molecular dynamics simulation for the reactionsof metal clusters with silicon atoms instead of silane as a preliminary study for the reactions of metalclusters with silane in order to get an insight into the underlying fundamental process. The calculations
were carried out for gold clusters Aun (n=3 to 14) and tungsten clusters Wn (n=3 to 14).
In the molecular dynamics simulation, we follow the Verlet method[16] to integrate the equations of
motion for a many particles system. The fundermental time step for the integration is 2 fs. The system isobserved for a time period of 800 ps which is long enough for the system to reach a certain stable state atlast. In general, the effective potential should play a crucial role for the evolution of the whole system inproblem. In this connection, we refer to the ab initio calculations. A Gupta potential [17,18] is used for
Au-Au interaction, a Morse potential[19] for W-W interaction, and Lennard-Jones potential[20] for otherinteractions. Acctually,


−p

r

ij

−1





(1) Gupta potential

VG = ∑ ε0 ∑i= j e(2) Morse potential
VM = D e−2λ (r−r0 ) − 2e−λ (r−r0 ) ,

r0n

−

−2q

ξ 2 ∑i= j e

r

ij

r0n

−1



,

and

(3) Lennard-Jones potential VLJ = 4ε



6
σ 12
− σr
,
r

where ε , σ , ε0 , ξ , p, q, D, λ are parameters which are different in materials.
At first, the reaction in which a gold cluster absorbs silicon atoms is simulated. The cluster size is 3
to 14. Both binding energies of absorbed silicon atoms and geometrical structures of resulting systems
are examined. Figure 1 is the result. The figure takes a gold cluster size for horizontal axis, binding
energy of a silicon atom which is absorbed by a gold cluster for vertical axis. From this figure, we findthat the binding energy increases with an increase of cluster size for the cluster size up to 6, while it isalmost constant for the cluster size is greater than 6. For comparison, the reaction in which a tungsten
cluster absorbs silicon atoms is simulated. The cluster size is 3 to 14. Figure 2 is the result. The figuretakes a tungsten cluster size for horizontal axis, binding energy of a silicon atom which is absorbed by a

- 45 -

gold cluster for vertical axis. We find that the binding energy is almost constant for all the cluster size
examined.
Figure 3 shows the geometrical structure of resulting system when a gold cluster of the size 6 absorbs
a silicon atom. It is shown that the silicon atom enters into the gold cluster and attains its large binding
energy surrounded by gold atoms. When the cluster size is changed from 3 to 14, it is found that the
number of surrounding gold atoms increases with an increase of cluster size up to 6 and becomes almost
constant for the cluster size greater than 6. Figure 4 shows the geometrical structure of resulting system
when a tungsten cluster of the size 6 absorbs a silicon atom. It is shown that the silicon atom attaches toa peripheral site of the tungsten cluster. In this case, the number of tungsten atoms attached to the silicon
atom is almost constant under the change of cluster size from 3 to 14.
The simulation for gold cluster suggests the existence of substantially new material which has notbeen expected previously, i.e., a two-components hybrid cluster with a Si-Au core-shell structure, andshows a drastic change in contrast to the case of tungsten cluster in which a W-Si core-shell structure isfavoured. We conclude that inter-molecular potentials make such a big difference between a gold-silicon

-5

0

-6

-2

Binding Energy [eV]

Binding Energy [eV]hybrid cluster and a tungsten-silicon hybrid cluster.

-7
-8
-9

-10

-6
-8

-10

-11
-12
2

-4

4

6

8
10
Cluster Size

12

-12
2

14

4

6

8
10
Cluster Size

1214

Fig. 1. Relation of a gold cluster size and binding energy of a silicon atom

Fig. 2. Relation of a tungsten cluster size andbinding energy of a silicon atom

Fig. 3. Final state of Au6 − Si reaction

Fig. 4. Final state of W6 − Si reaction- 46 -

References[1] A.Negishi, N.Kariya, K.Sugawara, I.Arai, H.Hiura, and T.Kanayama, Chem. Phys. Lett.
388(2004)463.
[2] H.Hiura, T.Miyazaki, T.Kanayama, Phys. Rev. Lett. 86(2001)1733.
[3] T.Kanayama, Jpn. J. Appl. Phys. 33(1994)L1792.
[4] T.Kanayama, H.Murakami, J. Vac. Sci. Tech. B15(1997)2882.
[5] T.Miyazaki, H.Hiura, T.Kanayama, Phys. Rev. B66(2002)121403(R).
[6] S.M.Beck, J, Chem. Phys. 87(1987)4233;
S.M.Beck, J, Chem. Phys. 90(1989)4233.
[7] M.Sanekata, T.Koya, S.Nagao, Y.Negishi, A.Nakajima, K.kaya, Trans. Matter. Res. Soc. Jpn.
25(2000)1003.
[8] M.Ohara, K. Kouyasu, A.Nakajima, K.Kaya, Chem. Phys. Lett. 371(2003)490.
[9] M.Ohara, K.Miyajima, A.Pramann, A.Nakajima, K.Kaya, J.Phys. Chem. A106(2002)3702.
[10] V.Kumar, Y.Kawazoe, Phys. Rev. Lett. 87(2001)045503.
[11] S.N.Khanna, B.K.Rao, P.Jena, Phys. Rev. Lett. 89(2002)016803.
[12] J.Lu, S.Nagase, Phys. Rev. Lett. 90(2003)115506.
[13] C.S. Ye, S.Afzaal, S.A.Lee, Y.G.Buun, B.S.Freiser, J. Am. Chem. Soc. 116(1994)8806.
[14] Y.G.Byun, B.S.Freiser, J. Am. Chem. Soc. 118(1996)3681.
[15] Y.G.Byun, S.A.Lee, S.Z.Kan, B.S.Freiser, J. Am. Chem. Soc. 100(1996)14281.
[16] L.Verlet, Phy. Rev. 159(1967)98. R.P. Gupta, Phys. Rev. B23(1981)6265.
[17] F.Cleri and V.Rsato, Phys. Rev. B48(1993) 22.
[18] R.P.Gupta, Phys. Rev. B23(1981)6265.
[19] P.M. Morse, Phys. Rev. 34(1929)57.
[20] H.Häkkinen, M.Moseler, and U.Landman, Phys. Rev. Lett 89(2002)033401-1.

- 47 -

3.8

Charge- and velocity- dependence of charge transfer reaction between
HCI and C60

Y. Takanashi, M. Kubo, H. Sasaki1 and I. Arai
A highly charged ion(HCI), when it comes near a material surface, removes the electrons bound on thesurface via an over-the-barrier ionization in presence of its deep Coulomb potential[1]. At the same time, ahuge energy is released at around the local site. We have used a C60 as a target and observed a chargetransfer reaction between a HCI and C60.

Such an observation is expected to play a crucial role forunderstanding the whole ionization process on a material surface caused by an HCI in connection to thecorresponding ionization process of a single atom caused by an HCI. In the present study, the observation
has been done under changing the charge state of HCI and its velocity systematically.
The experimental setup is as follows. The C60 target is prepared by an effusive source with atemperature of 400oC. The HCI beam produced by SHIVA, i.e., an ECR ion source at Tandem Accelerator
Center, is led to the interaction region between the extraction electrodes, where the beam crosses the C60
molecules, followed by the Time-of-Flight (TOF) mass spectrometer. Actually, the HCI beams of Arq+
(q=4-12, E=5q-15q [keV]) and Xeq+ (q=6-30, E=6q-15q [keV]) are used. The secondary ions produced by
HCI-C60 collision are extracted to the TOF mass spectrometer and analyzed along with theirmass-to-charge ratios. Figure 1 shows a typical TOF spectrum of collision products when 60 keV Xe12+
beam is applied. The horizontal axis is a TOF and proportional to a square root of mass-to-charge ratio. In
the figure, the prominent peaks assigned to the charge states of C60 as C60+, C602+, … , and C606+ are
observed.
1500

C604+

1000

C603+

C602+

C60+

C605+
500

0

C606+
0

200

400

600

800

Channel (TOF)
Figure 1. Typical TOF spectrum of collision products for 60 keV Xe12+
The yield Y(n) of each C60n+(n=1-6) ion is obtained by integrating the corresponding peak approximatedby a Gaussian distribution function. We define the mean charge Q of C60 as follows;∑ n Y ( n)Q=
∑ nY (n)2Figure 2 shows the correlation between Q and the charge of projectile HCI as well as the calculations with- 48 -

use of the classical over-the-barrier (COB) model[2]. It is found that Q seems to become higher
approaching the COB model calculations as the charge of projectile HCI becomes higher. As for thecorrelation between Q and the velocity of projectile HCI, it is found that Q seems to become higher
approaching the COB model calculations as the velocity of projectile HCI becomes slower. The similartendency concerned with the velocity of projectile HCI is also observed in the charge transfer reactions
between a metal surface and a HCI [3]. This fact implies a certain similarity between C60 and a bulk
surface.

4Ar30keV
Ar60keV
Ar75keV
Ar90keV
Ar120keV
Ar150keV
Ar180keV
Ar210keV
Xe60keV
Xe90keV
Xe120keV
Xe150keV
Xe180keV
Xe240keV
Xe250keV
Xe300keV
COB
COB2

3.8
3.6
3.4

Q

3.2
3
2.8
2.6
2.4
2.2
2
0

5

10

15
20
Charge of Projectile HCI

25

30

Figure 2.

Correlation between Q and the charge of projectile HCI

35

References[1] R. Morgenstern et al., in Proceedings of XXI International Conference on the Physics of Electronic andAtomic Collisions, Sendai, Japan, 1999, AIP Conf. Proc. No.500, edited by Y. Itikawa et al. (AIP, New
York, 2000).
[2] A. Baray et al., Nucl. Inst. and Meth. B98(1995)184.
[3] Q. Yan et al., Phys. Rev. A54(1996)641.

- 49 -

3.9

Mössbauer study on Fe nitride fine particles with high coercive force

K. Shibata, A. Hatanaka, E. Kita, H. Yanagihara and Y. Sasaki1
Iron nitrides have been studied as nobel magnetic materials for a few decades. A series of stable ironnitrides have been reported such as Fe4 N, Fe3 N and Fe2 N, which show various physical properties.[1]Fe4 N has a cubic perovskite crystal structure and has high Curie temperature of 480 ◦ C with almost
the same order of magnetization as α -Fe.[2] A hexagonal structure is realized from Fe3 N and Fe2 N andtheir Curie temperature changes from 294 ◦ C to near liquid He temperature.[3] A superior mechanicalcharacteristic is seen in this hexagonal iron nitride and has used as materials with excellent lubrication andablation resistance. Additionally, meta-stable Fe16 N2 has a body centered tetragonal structure[4] and wasreported to have larger magnetic moment than that of α -Fe.[5] Many have been researched to confirm thisgiant magnetization.[6]Many magnetic applications have been attempted by using iron nitrides which have been expected
to be more chemically stable compared with metallic materials, for example, head materials which require high saturation magnetization. Stable ferromagnetic metals have been studied in order to develop
high density magnetic recording media. Fe4 N metallic fine particles, which were fabricated by nitriding α -Fe fine particle with Ammonia-Hydrogen reaction technique, achieved significant improvement ofstability.[7]Recently, fine particles of Fe16 N2 were synthesized from needle shaped α -Fe fine particles utilized
for magnetic recording.[8] The magnetization showed slightly smaller amplitude of 170 emu/g than thatof bulk Fe16 N2 . Following the work, spherical ultra fine Fe16 N2 particles were produced by nitriding

γ -Fe2 O3 and they showed saturation magnetization of 200 emu/g which is higher than that of the former
work. Additionally, high coercive force greater than 2000 Oe was reported on the fine particles.[9] This
characteristic that high coercive force is realized in a spherical ferromagnet is quite suitable for the highdensity recording media.[10]From the point of nobel particulate recording media, we synthesized Fe16 N2 fine particles with AmmoniaHydrogen reaction technique and studied magnetic properties. In order to understand the magnetic andchemical structure of particles, Mössbauer study was carried out.
The nitridation was carried out similar way described in the literature.[8] A starting material was Fe
oxide particles with the diameter of about 20 nm. Prior to the nitriding, the particles was heated in anhydrogen atmosphere to reduce the oxides into metallic. Several tenths gram of oxides particles was set
into a small quartz boat and was heated up to 500 ◦ C for 1 to 3 hours. In this process, Fe oxides changed
into metallic Fe. Nitridation was carried out by heating particles to a reacting temperature (TR ) in themixed atmosphere of argon and NH3 gases. The reacting temperature were varied between 160 and 200◦ C. Reaction period was changed between 20 hours and 115 hours. Magnetic measurements was carriedout by using a vibrating sample magnetometer(VSM). MH curves were recorded at room temperature and
4.2 K in a maximum magnetic field of 15 kOe. Mössbauer study was carried out at room temperature and
4.2 K. Data were calibrated with natural α -Fe and were analyzed with a least squares fitting program.[11]From the fitting, hyper-fine field(H hf ), isomer shift(I.S.) and quadruple splitting(Q.S.) were obtained for
1 Hitachi Maxell- 50 -

Table 1. Reaction condition of FeN fine particles. Reaction time was fixed at 40 hours.

Sample
S21
S22
S23
S24

Reacting temperature
T R (◦ C)
175
178
174
168

Reacting gas(Ar/NH3 , sccm)
50/50
50/40
50/40
50/50

Ms(emu/g)

Hc(Oe)

122.0
107.3
106.3
119.4

1604
678
2146
1846

400
400

400

Fe16N2 (440), Fe(220)

Fe16N2 (404)

Fe16N2 (422)α-Fe(211)

Fe16N2 (224), (332)

Fe16N2 (400), Fe(200)Intensity ( arb.units )Fe16N2 (312)

Fe4N (111)
Fe16N2 (202)
Fe16N2 (220), Fe(110)each sub-spectrum.

300
300

300

S21

200
200

S22200

100

100
S23
100

S24
0
30

40

50

60

70

80

0 0
90

100

2θ ( degree )Fig. 1. X-ray diffraction patterns of Fe nitride particles, S21 to S24.

Figure 1 shows typical X-ray diffraction patterns of Fe nitride particles whose reaction condition issummarized in Table 1. Here, reaction time was fixed at 40 hours. Observed diffraction peaks originatedmainly from Fe16 N2 and slightly from Fe4 N and α -Fe. Especially, in the sample 23, trace of α -Fe was notobserved, however small trace from Fe4 N was detected. Other samples showed peaks due to α -Fe eventhe reaction condition differs very little from the sample 23. It is concluded that the reaction condition isquite sensitive to the composition of products and their magnetic properties.
Magnetic characteristics are also listed in the table. The magnetization was around 110 emu/g whichis half of that for α -Fe. It is noted that the magnetization already decreased in 120 emu/g for fine particles
after the hydrogen reduction process. The reason is that the magnetization was measured after the exposureof the sample into air and surface of fine particles was oxidized. In contrast, coercive force was widely
varied from 800 Oe to 2100 Oe. The highest coercive force of 2100 Oe was obtained in the sample 23. The- 51 -

amplitude was significantly enhanced by nitriding from the value of 660 Oe for un-nitriding Fe particles.

Transmission

1.40x10

6

1.38

Fe16N2 -:Fe(4d)-:Fe(4e)-:Fe(8h)α-Fe -:α-Fe
Fe4N -:Fe(1a)-:Fe(3c)A-:Fe(3c)B
Fe-O -:Fe-O

1.36

S23
Room temperature

1.34

-10

-5

0

5

10

Velocity (mm/s)
Fig. 2. Mössbauer spectrum of Fe nitride particles, S23, recorded at room temperature.

Table 2. Mössbauer fitting parameters for the sample S23 at room temperature.

Component
Fe16 N2

Fe4 N

α -Fe
DoubletSites
Fe(4d)
Fe(4e)
Fe(8h)
Fe(3c)B
Fe(3c)A
Fe(1a)

H hf (kOe)
294
318
405
224
215
320
333

I.S. (mm/s)
0.04
0.18
0.16
0.27
0.18
0.07
0.02

Q.S. (mm/s)
-0.37
0.22
-0.18
0.12
-0.43
0
0

Area (%)
16
24.1
12.5
9.6
2.8
3.8
8.5
22.7

Mössbauer spectra for the sample 23 were recorded at room temperature and 4.2 K (see Figs. 2 and
3). Fitted parameters were listed in Table 2 for room temperature and Table 3 for low temperature. The
sub-spectrum with greater hyper-fine field(400 kOe) than that of α -Fe(330 kOe) is clearly seen in theroom temperature spectrum. This sub-spectrum is assigned to the Fe(8h) site of Fe16 N2 . From the lowtemperature experiment, it is found that about 50 % of Fe atoms belongs to Fe16 N2 , and 20 % forms in
Fe4 N. Surface Fe atoms were evaluated to be 25 % and mainly form magnetically ordered oxides with H hf
of 485 kOe and IS of +0,72 mm /s at 4.2 K. These large hyper fine field and isomer shift suggest that the Featoms are in divalent. Relatively large distribution in H hf was observed in this sub-spectrum and it implies
that the atoms are located at the surface region of the particle with low symmetry. It is noted that this sub-- 52 -

6

1.00x10

Transmission

0.98

0.96
Fe16N2 -:Fe(4d)-:Fe(4e)-:Fe(8h)α-Fe -:α-Fe
Fe4N -:Fe(1a)-:Fe(3c)A-:Fe(3c)BD-:Fe-O
M-:Fe-O

0.94
S23
4.2 K
0.92

-10

-5

0

5

10

Velocity (mm/s)
Fig. 3. Mössbauer spectrum of Fe nitride particles, S23, recorded at 4.2 K.

spectrum was not observed in a room temperature spectrum and a non-magnetic doublet appeared. There
was no clear change in the temperature dependence of magnetization, therefore the phase with H hf of 485
kOe is concluded to be antiferromagnetic where the transition temperature lies below room temperature.
The reduction of magnetization in an ultra fine Fe particle is usually discussed with the surface oxidization. In the present case, 50 % of reduction was observed, however Fe atoms belonging to the surface
region is estimated as 25 %. Assuming that Fe atoms in the Fe16 N2 and Fe4 N phases have bulk α -Fe andFe4 N magnetization (210 and 180 emu/g, respectively), about 150 emu/g of magnetization is expected in
the sample 23. This discrepancy might be originated in the imperfect crystal structure in both Fe16 N2 andFe4 N phases. The sample preparation for the magnetic and Mössbauer measurements were carried out inTable 3. Mössbauer fitting parameters for the sample S23 at 4.2 K.

Component
Fe16 N2

Fe4 N

α -Fe
Oxide
DoubletSites
Fe(4d)
Fe(4e)
Fe(8h)
Fe(3c)B
Fe(3c)A
Fe(1a)

H hf (kOe)
312
333
425
245
275
346
342
485

I.S. (mm/s)
0.15
0.3
0.3
0.39
0.46
0.08
0.2
0.72

- 53 -

Q.S. (mm/s)
-0.41
0.26
-0.2
-0.09
0
-0.08
0
-0.48

Area (%)
14.3
21.3
14.3
11
5.9
4.9
2.9
18.9
6.5

air, then oxidization must proceed after the nitriding reaction. The large magnetization about 200 emu/g
has been reported in the fine particle sample under the careful handling after the reaction.[9] Next step forthis research must be the dealing the samples without exposing to air.
The enhancement of coercive force observed in the nitride fine particle is considered to be due to theformation of the Fe16 N2 phase. The crystal structure of this phase is body centered tetragonal (bct) andis distorted from the cubic symmetry. Deformation from cubic symmetry must produce the 2nd ordermagnetic anisotropy along the elongated axis, which is necessary for the spherical fine particles to havehigh coercive force. High coercive force is realized in an ordered phase (L10 ) of face centered tetragonal(fct) materials such as FePt and CoPt, which are leading candidates for the future high density recording
media. In this sense, Fe16 N2 will be one of them after improving the oxidization resistance.

References[1] for example see E. Kita and A.Tasaki, Sorid State Physics(Kotai Butsuri), 19, 721(1984)(in Japanese).
[2] G. Guiland and H. Creveaux, Compt. Rend., 222, 1170(1946).
[3] N. DeCristofaro and R. Kaplow, Metall. Trans. 8A, 425(1977).
[4] K. H. Jack, Proc. Roy. Soc. London, A208, 216(1948).
[5] T. K. Kim and M. Takahashi, Appl. Phys. Lett., 20, 492(1972).
[6] for example see J. M. D. Coey, J. Appl. Phys., 76, 6632(1994).
[7] K.Tagawa, E.Kita and A.Tasaki, Jpn. J. Appl. Phys., 21, 1596(1982).
[8] A. Nagatomi et al., J. Jpn. Soc. Powder and Powder Metal., 46, 151(1999) (in Japanese).
[9] T. Hattori, N. Kamiya and Y. Kato, J. Magn. Soc. Jpn., 25, 927(2001)(in Japanese).
[10] for example see A. Moser et al., J. Phys. D35, R157(2002).
[11] MossWinn for windows Ver 3.0- 54 -

3.10 Anelasticity study of nanocrystalline FCC metals
H. Tanimoto, N. Yagi and H. Mizubayashi
1. INTRODUCTION
Polycrystalline materials with an ultrafine crystallite size less than 100 nm are called as nanocrystalline(n-) materials, and have a unique structure in which the ultrafine crystallites are connected by grain boundaries (GBs).

When the ultrafine particles are mechanically consolidated, the highly disordered GBs may beformed to accommodate the neighboring ultrafine crystallites.

After these considerations, it is expected thatthe n-material possesses a new property which is different from that of the (p-) crystalline and amorphoussolids or the ultrafine particles [1]. In this paper, we report that fully-dense n-Au shows a quite large anelastic strain in the quasi-static measurements above 200 K, and the unique stress dependence of thesteady-state creep reflecting the characteristic GB properties in n-Au.
2. EXPERIMENTAL PROCEDURE
The gas-deposition (GD) method was originally developed to draw metallic thin line patterns on a substrate as interconnects [2]. The GD apparatus used for the high-density n-metal preparation is composed ofan evaporation chamber, a deposition chamber, a transfer pipe connecting these chambers and a helium circulation system with purification columns [3].

Ultra-fine Au particles formed by a gas condensation proc-

ess in the evaporation chamber were sucked by the transfer pipe and transferred onto a cooled glass substratein the deposition chamber.

The purity of the helium gas was kept as high as 99.9999 % in order to obtain

contamination-free and fully-dense specimens.

By controlling the position of the substrate, ribbon likespecimens of 23 mm long, 1 mm wide and 20 ~ 500 µm thick were prepared. We shall refer the 23 x 1 mm2surface side as the specimen flat surface, hereafter. After the deposition, the specimens were carefully removed from the glass substrate, where no bending and breaking of the specimens were found.
The mean grain size (d) was measured from the STM surface topography and the peak broadening in X-ray
diffraction (XRD) peaks. The XRD patterns were measured in a θ-2θ scan mode with Cu-Kα radiation,
where the measurements were performed at two different geometrical set-ups, i.e. the scattering vector was
normal (q⊥ set-up) and parallel (q// set-up) to the specimen flat surface.
The resonant frequency ( f ) and internal friction (Q-1) measurements were performed by the flexural vibrating reed method at f ~ 200 Hz and the strain amplitude of ~ 10-6. The stress relaxation measurement
was carried out by using the specially tuned Instron-type tensile testing apparatus [3]. Tensile creep test
apparatuses designed for a thin ribbon specimen and a compressive creep test apparatus for thick specimens
were home-made, where the creep strains under a constant load were measured using an capacitance displacement sensor [4].
3. RESULTS AND CONCLUSION
Quite strong reflections from the (111) planes were observed in the XRD spectrum measured at the q⊥
set-up, while various reflections were detected with comparable strengths at the q// set-up.

- 55 -

These XRD pat-terns indicate that almost all the crystallites in n-Au aligned their <111> crystallographic direction being
normal to the specimen flat surface. The values of d⊥ estimated from the (111), (200) and (220) reflection
peaks is about 38, 25 and 20 nm, respectively. The STM surface image of n-Au showed dome-like swellswith the mean diameter of about 25 nm and no pores and cracks are observed. The density (ρ) of the n-Au
specimens was 19.4 ± 0.2 g/cm3, and it shows good agreement with ρ0 = 19.32 g/cm3 of the bulk Au value in
Almost no change in ρ of the present n-Au was observed after the annealing at 1100 K [5].

literature.

In the tensile test with the strain rate (dε/dt) of 1.5 x 10-4 s-1, the linear elasticity is found up to strain (ε) of
1 % at 77 K, and up to ε of 0.5 % at 293 K, respectively. At around 300K, n-Au specimens show a fracturestrain of 1.5-3%, and the yield stress and tensile strength are about 3 times as large as those measured forannealed p-Au specimens. It is not shown here but in the f and Q-1 spectra observed for the n-Au specimenat ε ~ 10-6, a broad relaxation peak and small shoulders accompanied by modulus defects are observed ataround 95 K (Q-1p,95K, hereafter), 20 K and 50 K [6]. Above 200 K, Q-1 and f show a rapid increase and adecrease with increasing temperature (Q-1>200K, hereafter).

Both Q-1p,95K (including their shoulders) andQ-1>200K almost diminished after annealing for the grain growth [5,7]. For the n-Au specimens, after the
low-temperature irradiation with the Frenkel-defect concentration (CFP) up to ~ 100 ppm, Q-1p,95K including
their shoulders and Q-1>200K were remained almost unchanged, but f showed a large monotonous increase[6,7]. In contrast, for p-Au after irradiation with CFP < 1 ppm, a large decrease in Q-1 and a increase in f
(dislocation pinning phenomena) were simultaneously observed. These observations indicate that Q-1p,95K
and Q-1>200K are not due to dislocations but to some anelastic processes in the GB regions [8]. The tentative
TEM observation showed no dislocations in the present n-Au specimens (not shown here). It is noted that theTEM experiment reported dislocations in the crystallites of n-Au [9] but not in n-Ag [10].
The Young’s modulus of n-Au was estimated from the vibrating reed measurements at f ~ 200 Hz and ε ~10-6 (Evib, hereafter). The temperature dependence of Evib is shown in Fig. 1 together with that of Etensil,
which is the Young’s modulus observed from the tensile
Young's modulus / GPa

tests at dε/dt ~ 10-4 s-1 and ε ~ 10-3. Below 200K, the
p -Au

80

that of the Young’s modulus reported for p-Au [11,13].
Evib(as-prep .)70

temperature dependence of Evib and Etensil is quite similar toEtensil (as-p rep.)

Above 200 K, both of Evib and Etensil showed deviatory decreases from the Young’s modulus of p-Au, where the decrease in Etensil was larger than that of Evib.

This is due tothe anelastic strain (εan,>200K) which is thermally activated
0

100

200

300

Temperature / K
Fig. 1 Temperature dependence of Young’s
modulus observed for high-density n-Au.

above 200 K and increases nonlinearly with the increase in
the applied stress.

It is noted that Q-1>200K is indicative of

εan,>200K, and εan,>200K is commonly observed in n-fcc metals. On the other hand, as seen in Fig. 1, the modulus observed at 10 K is free from the anelasticity. The Young’s- 56 -

modulus found for the present n-Au specimens at 10 K is almost the same to that of p-Au after taking into
account the orientations of constituent crystallites [4, 5]. This fact indicates that the modulus of the GBs is
comparable with that of bulk Au.
The decrease in the Young’s modulus of n-Au above 200 K is larger at increased strains, and possibly for along-term test.

Figure 2 shows the results of stress-relaxation tests for n-Au, where the stress relaxation

was detected above 165 K and its amount increased with increasing temperature [11]. The relaxation timefor εan,>200K has a wide distribution and the anelastic process associated with the GBs are not of a simple relaxation process. To pursue the anelasticity of n-Au at the higher stresses, we carried out the creep test for 80
ks and the recovery test were sequentially made as a function of the applied stress (σap) and temperature.
The strain found just after unloading (ε80ks) is composed of an anelastic strain (εan,GB, where εan,GB ~ εan,>200K)
and a plastic creep strain (εpc,80ks).

εan,GB showed a saturation after 50 ks at 300 K. Figure 3(a) shows ε80ks

as a function of σap which were observed at 295, 310 and 320 K.

Figures 3 (b) and (c) show εan,GB and

εpc,80ks found near 80 ks as a function of σap, respectively. From Fig. 3(b), εan,GB increases linearly with increasing σap beyond the threshold stress (σanI) of a few
MPa.

It is noted that the stress level in the vibrating

10

reed measurements with ε ~ 10 was below σanI. A

8ratio of εan,GB to an elastic strain (εel) is as large as 1.1
at 320 K and 0.7 at 295 K for the present n-Au specimens, indicating that εan,GB/εel decreases with decreas-

ε80ks/10-3-6

Ean,GB for the early stage of the stress relaxation

6
4

0

(b)

lower than the activation enthalpy of 0.88 eV reported
Since a simple diffu-

εan,GB/10-3

study is reported to be 0.2 eV [11] which is much

2

1

165K

1

0

185K
180K

0.95

0.9

as-prep., σ0=147MPapressed, σ0=93MPa

0

100
200
Elasped time (s)

(c)

6

246K

εpc,80ks/10-3

Stress relaxation, σ(t)/σ0(a)2

ing temperature toward 200 K.

for the GB diffusion in p-Au.

320 K
310 K
295 K

251K

4
2

300

0

Fig. 2 Stress relaxation curves observed for n-Au in the
as-prepared state and after the press.

100

200

σap / MPa300

Fig. 3 Total (a), elastic (b) and plastic (c) strains observed
for n-Au after removing the constant load for 80 ks.

- 57 -

sion process with an activation enthalpy of 0.2 eV is well stimulated at 200 K, a value of the pre-exponential
factor for the atomic motion responsible for εan,GB should be very low. Recent molecular dynamics simulation studies for the GB diffusion [12, 13] and the GB migration [14] reported that cooperative motions ofmany atoms can be excited above a certain temperature, which results in a low activation enthalpy and a low
pre-exponential factor. We surmise that such a cooperative atomic motion of many atoms is responsible toεan,GB in the present n-Au. The wide distribution of the relaxation time for εan,GB may be associated with thescale of the cooperative motions.
Acknowledgements
This work is partly supported by a Grant in Aid for Scientific Research from the Ministry of Education,
Culture, Sports, Science and Technology of Japan and High Damping Materials Project of “Research for the
Future” of Japan Society for the Promotion of Science.
References
1. H. Gleiter, Prog. Mater. Sci., 33(1989)223-315.
2. S. Katus, E. Fuchita, T. Tanabe and C. Hayashi, Jpn J. Appl. Phys., 23(1984)L910 : E. Fuchita, M. Oda
and C. Hayashi, Materia Japan, 44(1995)455 (in Japanese).
3. S. Sakai, H. Tanimoto and H. Mizubayashi, Acta Mater., 47(1999), pp. 211-217.
4. S. Sakai, Thesis, University of Tsukuba, (2001).
5. H. Tanimoto, S. Sakai and H. Mizubayashi, Mater. Trans., 44(2003), pp. 94-103.
6. H. Tanimoto, H. Mizubayashi, H. Fujita and S. Okuda, J. de Phys., 6(1996)C8-199-202..
7. H. Tanimoto, S. Sakai, and H. Mizubayashi, Proc. ICIFUAS-13, submitted.
8. H. Tanimoto, S. Sakai, K. Otsuka, E. Kita and H. Mizubayashi, Proc. ICIFUAS-13, submitted.
9. S. Okuda, J. Alloy Comp., 310(2000)124
10. S. Ichikawa, K. Miyazawa, H. Ichinose and K. Ito, Nanostruc. Mater., 8(1999)1301.
11. S. Sakai, H. Tanimoto, K. Otsuka, T. Yamada, Y. Koda, E. Kita and H. Mizubayashi, Scripta Mater.,
45(2001), 1313.
12. M.R. Sørensen, Y. Mishin and A.F. Voter, Phys. Rev. B, 62(2000)3658.
13. P. Keblinski, D. Wolf, S. R. Phillpot and H. Gleiter, Phil. Mag. A, 79(1999)2735.
14. B. Shönfelder, D. Wolf, S. R. Phillpot and M. Furtkamp, Interface Sci., 5(1997)245 : B. Shönfelder, P.
Keblinski, D. Wolf and S. R. Phillpot, Mater. Sci. Forum, 294, 9 (1999).

- 58 -

3.11

The science of 3d transition-metal oxide system (2003–2004)

M. Onoda, J. Hasegawa, T. Ikeda, T. Ohki, T. Harigae, S. Miyasaka, T. Mutoh, T. Isobe and K. Takao
The structural and electronic properties of 3d transition-metal oxides and bronzes have been exploredby means of x-ray four-circle diffraction and through measurements of magnetic resonance (NMR and
EPR), magnetization, and electronic transport, in order to extract characteristic properties in the correlated
electron system, electron-phonon-coupling system, quantum spin-fluctuation system, and novel materials.
At the Tandem Accelerator Center, Varian continuous-wave and Bruker pulse NMR spectrometers havebeen used.
In 2003–2004, the following investigations were performed and a part of them have been publishedelsewhere [1–3]:• Quantum spin-fluctuation system– Geometrical frustrations in Cdx Zn1−x V2 O4 and LiV2−x Mx O4 (M = Al and Ga)– Spin-gap states in δ -Mx V2 O5 (M = Ag, Tl, Na, K and Sr)• Correlated-electron and electron-phonon-coupling systems– Metal-insulator transitions in V6 O13 and Cux V4 O11• A new type of superconductors– Superconducting properties of Nax CoO2 ·yH2 O– Geometrical frustrations and electronic properties of Nax CoO2 and Lix VO2• Composite crystal system– Superspace group approach to Cux V4 O11• Secondary ion battery system– Li inserition effects in M1+x V3 O8 (M = Li, Na and Ag), Ag2 V4 O11 , Cux V4 O11 and V6 O13

This report describes briefly recent progress for the secondary ion battery system.

Secondary ion battery system
Li1+x V3 O8 is one of several vanadium oxide systems that have received considerable attention as an
insertion electrode. This system can accommodate around three or ideally four additional Li ions per
formula unit (namely x = 3 − 4).
For Li1+x V3 O8 with x < 2, there exist three crystallographically independent V sites (V1, V2 and V3).
The V1 ions apparently have a pyramidal coordination, while the V2 and V3 ions are surrounded octahedrally. The V3 O8 framework is comprised of the chains of VO6 octahedra and those of VO5 pyramids
extending along the monoclinic b-axis. These chains are connected by corner-shared oxygens to lead tocontinuous sheets of V−O polyhedra. The networks for the equivalent V1 and V2 sites are expressed as
zigzag chains and that for the V3 site is a one-dimensional chain. Although the linkage for the inequivalentsites complicates matters, the spin networks responsible for magnetic properies are often simplified due tothe symmetry of the ground-state wavefunction for each V site. The Li ions are located predominantly inan octahedral Li1 site (occupancy probability = 1.0). The excess xLi ions reside in a tetrahedral Li2 site.
In the highly lithiated crystal Li4 V3 O8 (x = 3), a defect rock-salt structure is formed and all of Li ions arecoordinated octahedrally.
Although the crystal structures and electrochemical properties of Li1+x V3 O8 system have been investigated in detail, there is little information on the electronic properties as a function of x. This work is- 59 -

5080(a) LiV3O8

40

60
40

c

20

∆Hs (G)∆Hs (G)

30

10

(b)

b

0
a*

–10

20

c

–20
–40

–20

–60

–30

–80
0

a*

0

30 60 90Θ (deg)030

60

90 120 150 180
Φ (deg)Fig. 1: The angular dependences of the interval ∆Hs between the 7 Li quadrupole satellites for m = ± 32 ↔
± 12 in LiV3 O8 at 15 MHz: (a) ba∗ - and bc-planes; and (b) a∗ c-plane. Here, all of the curves are calculatedwith parameters given in text.
performed in order to clarify the configuration of Li ions in Li1+x V3 O8 for wide compositions through
NMR and magic-angle-spinning (MAS) measurements.
The Knight shift of 7 Li nuclei for the single crystals of LiV3 O8 is absent, which indicates that theatoms are completely ionized. The angular dependences of the interval ∆Hs between the 7 Li quadrupole
satellites for m = ± 32 ↔ ± 12 at 15 MHz are shown in Fig. 1. Generally, the angular dependence of ∆Hs isexpressed by∆Hs = HQ (3 cos2 θ − 1 + η sin2 θ cos2φ ),(1)where HQ is the quadrupole field, η is the asymmetry parameter of electric field gradient (EFG), and θ
and φ are the polar and azimuthal angles of the magnetic field with respect to the principal axes of the
EFG tensor, respectively. On the basis of the data for ba∗ -, bc- and a∗ c-planes, the quadrupole field,
the asymmetry parameter and the directions of the principal axes are determined as: HQ = 36(1) G,η = 0.58(5),  (Z, a∗ ) = 57(1) deg and X  b. The directions of the EFG tensor are consistent with those
calculated from the point-charge model for the Li1 site using atomic parameters determined by Onoda andAmemiya [1]. However, this model provides a small value η = 0.06 as compared with the experimental
result.
Li1+xV3O8
x=0.0
1.0

Intensity (arb. unit)

1.44
1.74
2.6
2.9
3.2
3.3
4.6

10

20

30

40
2θ (deg)

50

60

70

Fig. 2: The composition dependence of the x-ray diffraction patterns with Cu Kα radiation for Li1+xV3 O8
prepared by the solid-state reaction (x = 0) and the electrochemical reaction (x = 0).

- 60 -

10

Li1+xV3O8
x=0.0
0.25
2.9
4.6

W (G)

8
6
4
2
0

100

200
T (K)

300

400

Fig. 3: The temperature dependences of the peak-to-peak linewidths of absorption derivatives for 7 Li
nuclei in Li1+x V3 O8 at 15 MHz.
Figure 2 indicates the x-ray diffraction patterns with Cu Kα radiation for the specimens prepared by
the solid-state reaction (x = 0) and the electrochemical reaction (x = 0). For Li1+x V3 O8 , it is known that
there exist two kinds of phase corresponding to the small x compound (0 ≤ x < 2) and the large x one(x ≥ 3), which are called the L1 and L4 phases, respectively. In this work, the single phase of L1 and thatof L4 appear for x ≤ 1.5 and x ≥ 4.0, respectively. The specimens with 1.5 < x < 4.0 have a mixed phaseof L1 and L4. The reason why the concentration of x = 4.6 given in Fig. 2 is larger than a maximum value
for L4 phase is that the excess Li ions are doped in acetylene-black.
For the compounds with x = 0.25, 2.9 and 4.6, the Li Knight shifts are absent as in the case of LiV3 O8 .
Since the specimen with x = 2.9 has the presence ratio of L4/L1  1 from the intensity ratio of x-ray
diffraction patterns, the resonance lines ascribed to the L1 and L4 phases should appear. However, only
the single line is observed, which suggests that the Li signal for the L1 phase is masked with that for theL4 phase and/or the local environment around Li ions for the maximum concentration in the L1 phase
is similar to that for the L4 phase. The temperature dependences of the peak-to-peak linewidths W ofabsorption derivatives at 15 MHz are shown in Fig. 3. The data for x = 0 and 0.25 are significantly
smaller than those for x = 2.9 and 4.6. For all of the compounds, a significant decrease of the linewidthwith increasing temperature occurs above room temperature, which should be attributed to the motion of
Li ions. For x = 2.9 and 4.6, a similar behaviour is also observed below 50 K.
The linewidth W dip due to the dipole interaction is estimated through the relation ofW dip = 2 M2 Li−Li + M2 Li−V + M2 0 ,(2)where M2 0 is the residual second moment at high temperatures and M2 Li−Li(V) is the second momentfor Li-Li(V) pairs defined by
9 2 2
1
h ∑ 6,
M2 Li−Li = γLi4rk k

M2 Li−V =21 2 2
1
γ h
,
6
5 V ∑
r
k k

(3)

γLi(V) and h being the gyromagnetic ratio of Li(V) and Plank’s constant, respectively. The values for x = 0,0.25, 3 and 4 calculated based on the available lattice constants and atomic parameters are W dip = 2.9,
3.5, 9.9 and 11.7 G, respectively. Therefore, it may be concluded that for x = 0 and 0.25, Li ions form rigid
lattices below room temperature, while for x = 2.9 and 4.6, they are ordered at the lowest temperature.
Above room temperature, the activation energies of the Li motion for x = 0, 0.25, 2.9 and 4.6 are
estimated with the equation of W − W0 ∝ exp(Eg /T ), W0 being the residual width, as follows: Eg  5.2,
6.7, 3.1 and 1.3 × 103 K, respectively. The Eg values for the large x are rather smaller than those for thesmall x. This may be originated from a large Coulomb repulsion between Li ions for the large x.

- 61 -

In summary, the configurations of Li ions in Li1+x V3 O8 for wide nominal compositions of 0 ≤ x ≤ 4.6
are clarified through 7 Li-NMR. For x = 0, the quadrupole interaction parameters for the Li1 site are determined precisely. The motion of Li ions is observed above room temperature for all of the compositions.
Below room temperature, Li ions for the small x are almost ordered, while for the large x, the Li ions movein a wide temperature region due to a large Li-Li Coulomb repulsion. The MAS-NMR measurements andthe analysis are now in progress.

References[1] M. Onoda and I. Amemiya: J. Phys.: Condens. Matter 15 (2003) 3079–3093.
[2] U. Manju, S. R. Krishnakumar, S. Ray, S. Raj, M. Onoda, C. Carbone and D. D. Sarma: Proc. Indian
Acad. Sci. (Chem. Sci.) 115 (2003) 491–498.
[3] K. Okazaki, H. Wadati, A. Fujimori, M. Onoda, Y. Muraoka and Z. Hiroi: Phys. Rev. B 69 (2004)
165104-1–165104-7.

- 62 -

4.1

Status of Tsukuba AMS system

Y. Nagashima, R. Seki, K. Sasa, T. Takahashi, T. Matsuhiro, K. Sueki
The molecular pilot beam method we have developed is a principal of our AMS system.
Applying this method to our traditional big, 12MV acceleration voltage, Pelletron tandem accelerator, wehave realized successfully an accelerator mass spectrometry (AMS) without any modifications on thetandem system.
In order to improve the beam intensity from the ion source, a supporting structure for the exit slitof the ion source has been changed from fixed type to adjustable one. The slit can be moved in the plane
perpendicular to the beam direction. The beam current emerging from the ion source became about double
after the slit position was adjusted properly. The double score of the current helps very much to shorten themeasurement time and to improve the statistics of the counts.
As one of the instrumental improvements, in the last year, two beam profile monitors wereprepared and has been installed into both an exit of an AMS ion-source and the first focus point of an
AMS beam line for 36Cl particle detection. We were expecting that these beam profile monitors help us tofind the optimum parameters of the optical elements. But, though the later one works well and is useful totransport the beam properly, the ability of the former one is in sufficient because the location of it is out offocus point.
If the AgCl samples were kept in the air for one day, the Sulfer will be built up on the face of the
AgCl sample and consequently the strong Sulfur contamination will disturb to count the 36Cl particles up.
In order to keep free from the Sulfur contamination, AgCl samples have been prepared just before the
AMS measurement. However, this way limits the number of the samples prepared because of lack ofenough time for preparation. So, a vacuum chamber with an oil free evacuation system, DRYTEL Model
1025, has been developed for keeping the samples in the oil free vacuum circumstances. There are noobservations of Sulfur increments in the measurements of samples that are preserved in the chamber for 2
weeks. This chamber allows us to prepare samples not only just one day before the measurement but also
several days before.
In order to discriminate 36Cl from 36S more clearly on the ∆E - E data map, a new gas counterthat consists of two gas ∆E sections, ∆E1 and ∆E2, and a SSD E has been developed. By using one ∆Esignal as a discrimination gate, Sulfur reduction ratio in 36Cl measurement is improved about 2%. Details
are described in the following section.
Up to now, Al- ions produced in the ion source are using for the 26Al AMS. Though the merit ofAl- ion lies on no simultaneous creation of Mg- ions and no interferences by the Mg ions, the intensity of
Al- is not enough strong for measuring of very rare 26Al sample such as one 26Al element in 1013 elementsof 27Al. So, in this year, the development of 26Al AMS method using AlO- molecular ions has beencommenced. A few µA of AlO- current can be produced and it is a few ten times of Al- current. Fig. 1
shows the outline of the 26Al-AMS system. The method introduced into the system is similar to that of 36Cl
AMS. The acceleration voltage is controlled precisely by a slit current feedback system. 26MgO- molecular- 63 -

ions are created simultaneously with AlO- ions in the ion source in order to produce the slit current with26

Mg7+ beam. In general, MgO- molecular ions are abhorred in the case of 26Al AMS because the strong

26

Mg yields causes the strong background and consequently disturbed the 26Al measurement. Nevertheless,we try to use them positively as a control current. A 2nd stripper foil plays a role of full stripped 26Al13+
creation. After passing through the 2nd stripper foil, 26Al13+ ions are selected and detected as a 26Al
element without 26Mg disturbance because of no 26Mg13+. The abundance of 26Al13+ is about 10%. The 26Al
detection efficiency with AlO- ions becomes about 4 times better than that of the case with Al- ions. The
sensitivity of 26Al detection is better than 1×1015.

- 64 -

4.2

Development of a multi gas ∆E - SSD E counter telescope for AMS study

He Ming1, Y. Nagashima, K. Sasa, R. Seki, T. Takahashi, T. Matsuhiro, and K. Sueki
Particle identification is sometimes essentially requested in the AMS measurements. In case of36

Cl AMS, clear identification of a 36Cl particle from a 36S background can improve the sensitivity of the36

Cl detection. Up to now, we are using a gas ∆E - SSD E counter telescope in the 36Cl measurement.

Combining with chemical procedures for Sulfur reduction in the stage of sample preparation, the counter
telescope can clearly separate the 36Cl particle and the 36S background and detect clearly the 36Cl comingfrom the sample which has 10-13 ratio of 36Cl to Cl. However, in proportion to decreasing of 36Cl content
such as 10-14 ratio, 36S background becomes relatively strong and 36Cl is buried in the 36S background. Inorder to improve this condition, a new counter telescope which consist of two gas ∆E sections and an ion
implanted SSD with 45mm×45mm active area has been developed. Fig. 1 shows the outline of the counter.
A 7.5µm thick poliimido foil, (Kapton, Tore-Dupon Co.), is used as an entrance window. The reasons why
we chose the Kapton foil are that 1) Kapton foil is strong to the radiation damage and 2) there is noobservation of gas leakage at 100mbar gas, pure iso-butane

gas, pressure. After passing through the

Kapton foil, a 90MeV 36Cl particle losses it's energy of about 21MeV. This large energy missing causes alowering of particle identification ability. So, a 3.5µm thick myler foil has been tried to use instead of the
Kapton. The small gas leak, however, observed even if at 20mbar gas pressure. It is trying to find out aproper thin and strong foil, but at this moment it is not yet.
Before throwing this in the AMS experiment, optimum operating conditions were examined byusing Americium α. One of the results is shown in Fig. 2. The resolution of ∆E output improves with theincrease of grid voltage and reaches to the maximum at around 350V. The optimum grid and anodevoltage for a 90MeV 36Cl measurement with 40torr gas pressure are 330V and 430V, respectively. Theenergy losses, ∆E/∆x, of 36Cl, 36S, 35Cl and 37Cl particles in the gas ∆E sections are schematicallydemonstrated in Fig. 3. The SSD measured the residual energy and gas pressure is set as the residualenergy difference between 36Cl and 36S becomes maximum.
Fig. 4 demonstrates that how efficient the ∆E signal is when it is used as the gate information. A
left figure in Fig. 4 shows the 36Cl yield taken with ∆E1 gate. A right side one shows the raw data. The
difference, though it is not so large, can be seen. A tail of 36S background is comparably suppressed andconsequently 36S background yield in the 36Cl yield becomes small.

1

Present address ： China Institute of Atomic Energy- 65 -

Fig. 1 Cross section of a gas ∆E - SSD E counter telescope. The counter consist of
two gas ∆E sections and an ion implanted SSD with 45mm×45mm

Fig. 2 Grid voltage vs. Energy resolution. The iso-butane gas pressure is 40torr- 66 -

Fig. 3 Particle range vs. stopping power. The 36Cl with 90MeV is assumed.
The energy loss in the Kapton foil, about 20MeV, is counted in.

Fig. 4 Comparison of the influences of 36S background on the 36Cl yieldwith and without gate operation by ∆E1 signal.

- 67 -

4.3

An environmental study with 36Cl contents in the soils from many
places in Japan

T. Matsuhiro, R. Seki, Y. Nagashima, K. Sasa, T. Takahashi, Y. Tosaki, He Ming1, K. Sueki, K. Bessho, H.
Matsumura, T. MiuraIn our previous measurements of the 36Cl contents in the several soils sampled at around
Tokai-village, we could demonstrate the ratios of 36Cl to Cl of the Tokai soils are 10 to 100 times larger
than the ratios of Tsukuba soils. At that moment, we regarded Tsukuba soils might be the backgroundsamples because there are no nuclear facilities in the circumference of Tsukuba city. This estimation is,
however, only speculation.
In order to confirm the results of Tokai village, both of an average and a fluctuation of 36Cl
contents in the soils of Japan are essentially important information. So, this year, we started the samplingof soils in Japan and commenced the measurements of 36Cl contents in them. The soils in outer most layer
were only sampled because radioisotope fallout in the atmosphere reaches first to the soils on the earth
surface. Sampling points are carefully selected. An agricultural land, farm, creation land, reclamation land,
and well-maintained places were counted out. The places in which there are no human activities have been
selected. The back yard of a shrine was one of a nice candidate. Fig. 1 shows the sampling places in Japan.
The sampling points were widely scattered from northern part of Japan, such as Hokkaido, to southern partof Japan like Nagasaki. The ratios 36Cl : Cl are summarized in the Fig. 1. The average ratio of 36Cl to Cl
derived from 36Cl AMS measurements of 23 samples corrected from 14 places in Japan is (4.7 ± 3.6) ×
10-13. The background ratios of 13 places fall within the order of 10-13, but the Batoucho Nasu Tochigi
gives 10-12 order of ratio. The origin why Batouchou gives so large ratio is not clear now.
Adding to the measurements of 36Cl background, it is very interesting to compare the results ofTokai village with the results of the 36Cl contents in the soils sampled in the vicinity of another nuclear
facilities. Two big nuclear power plants are in Fukushima and total 10 BWRs are operated stationary formore than 30 years. We chose these sites for the comparison study. Total 21 places were selected as the
sampling points and are summarized in Fig. 2 together with the ratio of 36Cl to Cl. The average ratio of36

Cl to Cl derived from 36Cl AMS measurements of 21 places is (4.6 ± 2.7 ) × 10-13. This ratio has nodifference from the average background ratio of Japan. In contradiction to the results of Tokai village, it isobvious that there is no radioisotope leakage to the environment from the Fukushima nuclear power
facilities.
Fig. 3 shows the chemical procedures for taking out Chlorine from the soil. After drying up, thesoils is added 0.8M nitric acid and the mixture is separated into a solution and a residuum with acentrifugal separator. The solution contains Chlorine species. In order to improve the collection efficiency,
the residuum is mixed into pure water and is repeated centrifugal separation again. The purpose ofammonium addition in the second step is to separate the metal such as Fe and Al. the metals are separated

1

Present address China Institute of Atomic Energy, Beijing, China- 68 -

from Chlorine with another centrifugal separation. The solution is concentrated to about 10ml by heating
up. Then, the condensed solution is changed to acidity with concentrated nitric acid. As final step, In orderto take Chlorine out as a silver chloride, 0.25M silver nitrate is added into the condensed solution. In
average, about 10mg of Silver chloride can be collected from about 100g of soils with this procedure.

Fig. 136

Cl background map. The backgrounds are expressed as a ratio of 36Cl to Cl.

- 69 -

Fig. 2

The ratios of 36Cl to Cl. The 6 BWRs are running in Fukushima 1st nuclear power plant and4 BWRs are working in Fukushima 2nd nuclear power plant.

Fig. 3Sample preparation scheme. Cl contents in soil are extracted as Silver chlorine.

- 70 -

4.4

Application of 36Cl as a tracer in groundwater hydrology

Y. Tosaki, N. Tase, Y. Nagashima, R. Seki, T. Matsuhiro, T. Takahashi, K. Sasa, M. He, K. Sueki, T. Miura1,
K. Bessho1 and H. Matsumura1
For the continuous use of groundwater resources, the knowledge of groundwater residence time plays very
important role. Tritium (3H) is one of the useful environmental tracers in groundwater study because its fallout
rates had a peak caused by nuclear bomb tests conducted during the 1950s and 1960s. Due to the short halflife (12.43 years), however, the 3H bomb peak has been attenuated recently through radioactive decay. Hence,
the groundwater tracer which can estimate the residence time of several decades is necessary in place of 3H.
Chlorine-36 (36Cl) also had a bomb peak in its fallout rates mainly caused by oceanic nuclear bomb tests [1].
The 36Cl has a half life of 301000 years which is much longer than that of 3H, so the bomb peak has not been
attenuated through radioactive decay. Therefore, the 36Cl bomb peak can be a tracer in groundwater study. The
objectives of this study are to investigate whether the 36Cl bomb peak could be used as a tracer in groundwaterand to explain the relation between the distributions of 36Cl in groundwater and the residence time ofgroundwater.
Some groundwater samples were collected from observation wells at Tsukuba Upland, Ibaraki (Fig. 2).
Site 1 is the experimental field at the Terrestrial Environment Research Center, University of Tsukuba. Site 2
is located at the northeastern part of Tsukuba

Water sample← conc. HNO3 (1 ml)

Upland. Detail of Site 2 is described in Fig. 3.
Collected

Groundwater

samples← 0.25 M AgNO3 (1 ml)

were

Centrifugation (3000 rpm, 10 min)prepared as AgCl (Fig. 1). The 36Cl/Cl ratios ofSupernatantthe groundwater samples were measured by the
AMS at the Tandem Accelerator Center,
University of Tsukuba.
The results ofPrecipitate (AgCl)← 3 M NH4OH (2 ml)

Sulfur Reduction← sat. Ba(NO3)2 (3 ml)
Filtration (0.20 µm Syringe Filter）

36

Cl measurements ofgroundwater samples are shown in Fig. 4-6. The

Filtrate ([Ag(NH3)2]+ Cl−)

36

Cl/Cl ratios of deep← conc. HNO3 (0.5 ml)

groundwater were somehow higher than those ofCentrifugation (2000 rpm, 15 min)results demonstrate thatshallow one. It suggests that the 36Cl produced

Supernatant

Precipitate (BaSO4)

Precipitate (AgCl)by oceanic nuclear bomb tests during the late×2

1950s still remains in deep groundwater. The

Wash (0.01 M HNO3, EtOH) × 3

36results of this study indicate that the Cl bomb
Dry (130°C, 3 h)peak could be used as a tracer in groundwater.

Fig. 1. Sample preparation for 36Cl AMS measurement.
Reference[1] H.-A. Synal, J. Beer, G. Bonani, M. Suter and W. Wolfli, Nucl. Instr. Meth. B52(1990)483-488.

1

Radiation Science Center, High Energy Accelerator Research Organization- 71 -

−20
0

−10

0

10 (m)

10
Lowland

20
30
40
50

Site 2-2

60

Upland70

Site 2-1

80

N

90
(m)

(m)

N

Fig. 3. Detail of Site 2.

Fig. 2. Location 24
of sampling sites.

Depth (m)0Height (m)26

12.7 ± 4.9

2

Sand

Sand
24

5.2

Clay

8

26.6 ± 2.4

5.4 ± 0.9

Clay

20

3.2 ± 0.7

Loam

18

16.6 ± 2.0

22

Loam

Sand and Gravel

Clay and Sand

16

Cl/Cl ratio (× 10−14)

36Clay and Sand

14

18.5

36

Soil

Cl/Cl ratio (× 10−14)

12Fig. 5. 36Cl/Cl ratios of groundwater at Site 2-1.

Fig. 4. 36Cl/Cl ratios of groundwater at Site 1.

−20 −1000

10 (m)

10
W2

20
30
Height (m)
28

36

W2

24
20

W-I

0

60

20.2 ± 2.5

22.6 ± 1.7

3.3 ± 1.7

20

40

Clay

Clay and Sand50

W148.3 ± 1.7

60
Loam
Clay

W14

70
80
90
(m)
80

100 (m)Sand (Brown)
Sand (Blue)

Fig. 6. 36Cl/Cl ratios of groundwater at Site 2-2.

- 72 -

W5

40

Cl/Cl ratio (× 10−14)14.5 ± 1.9

25.7 ± 1.9

16

W5

W-I

Sand (Green)
Sampling Point

N

4.5

AMS measurement of 36Cl in shielding concrete of various accelerator
facilities

K. Bessho1, H. Matsumura1, T. Miura1, Q. Wang1, K. Masumoto1, T. Matsuhiro, Y. Nagashima,
R. Seki, T. Takahashi, K. Sasa and K. Sueki
At the accelerator facilities, shielding concrete and concrete walls around beam lines are exposed
to secondary particles during machine operation, and various radionuclides are produced and accumulated
in them. Quantitative evaluation of radionuclides induced in the shielding concrete is important forradioactive waste management in reconstruction or decommissioning of accelerator facilities. Most of
the main radionuclides can be directly determined by a Ge detector for γ-emitters and a liquid scintillation
counter for β-emitters such as 3H, respectively[1]. On the other hand, long-lived 36Cl can be measured
only by accelerator mass spectrometry (AMS) because of its high detection sensitivity to 36Cl. Last year,
our group developed the suitable sample preparation for AMS of 36Cl in the concrete of accelerator
buildings and successfully applied for three kinds of accelerator facilities[2]. In this year, accuracy andreproducibility of the method were reexamined, and concrete samples collected at other accelerator
facilities were analyzed.
The AMS system constructed in the 12UD tandem accelerator of UTTAC has been applied for36

Cl analysis in soil and concrete samples related to Hiroshima atomic bomb, JCO critical accident, andother environmental samples[3,4]. The UTTAC 36Cl AMS system is suited for the 36Cl / 35Cl ratio in therange 10-10 - 10-13, while the 36Cl / 35Cl ratios in the above samples are in the range 10-12 - 10-13, so the
AgCl targets for AMS can be directly prepared by the extraction of Cl from concrete and soil samples.
On the other hand, the 36Cl / 35Cl ratios in shielding concrete exceed 10-9 and are too high for applying
AMS. Therefore the following procedure was developed. Chlorine in concrete samples was partiallyextracted into dilute nitric acid by heating in a tightly closed vessel. After the concentration of Cl
extracted from sample was determined with an ion chromatography, the 36Cl / 35Cl ratio of Cl was diluted
by adding a suitable amount of NaCl solution, in which 36Cl / 35Cl ratio was less than 10-13. Chlorine was
precipitated as AgCl by adding AgNO3 solution under the acidic condition. The target preparation
scheme including dilution steps was described in detail in the pervious report[2]. Amounts of concrete
samples are 1 - 5 g when 36Cl / 35Cl ratios in samples are higher than 10-10.
Validity of the sample preparation was evaluated by comparing the 36Cl / 35Cl ratios obtained at
different dilution factors.

Table 1 shows examples of the 36Cl / 35Cl ratios determined by AMS

measurements and the calculated original ratios in concrete samples. Samples No. 1 - 4 were collectedfrom various accelerator facilities. For sample No. 1, we prepared two kinds of AgCl targets which arewith or without dilution after Cl extraction. The 36Cl / 35Cl ratio of the diluted sample was in agreementwith the ratio of the sample without dilution. For sample No. 2, AMS results of three kinds of dilution
factors gave agreed results of the original 36Cl / 35Cl ratios. Similar results were obtained for sample No.
1

Radiation Science Center, High Energy Accelerator Research Organization- 73 -

3 and No.4. All of these results proveaccuracy and reproducibility of this36

procedure.

36

In this year, concrete samples
were obtained at 1.3 GeV electron
synchrotron ( Tanashi Branch,
Energy35

Table 1 Examples of the Cl / Cl ratios determined by AMS
measurements and the calculated original ratios in concrete samples

Accelerator

High

Research

Dilution
Sample factor
No.1

Organization ), AVF cyclotron and ring
cyclotron ( Research Center for Nuclear

No.2

Physics, Osaka University ). The depth
profiles of 36Cl / 35Cl ratios in these

No.3

concrete samples were analyzed. Other
radionuclides were also measured with

No.4

a Ge detector or a liquid scintillation

35

Cl / Cl

AMS measurement

Calculated original ratio

1( 7.46 ± 0.59 ) x 10

-11

( 7.46 ± 0.59 ) x 10

-11

33.5

( 2.36 ± 0.13 ) x 10

-12

( 7.90 ± 0.44 ) x 1060

( 5.43 ± 0.19 ) x 10

-12

( 3.26 ± 0.11 ) x 1075

( 4.60 ± 0.28 ) x 10

-12

( 3.43 ± 0.21 ) x 10

83

( 3.99 ± 0.35 ) x 10

-12

( 3.30 ± 0.29 ) x 10134

( 9.51 ± 0.42 ) x 10

-12

( 1.27 ± 0.06 ) x 10

192

( 7.16 ± 0.63 ) x 10

-12

( 1.37 ± 0.12 ) x 10

37.4

( 4.02 ± 0.14 ) x 10

-11

( 1.50 ± 0.05 ) x 10

331

( 4.86 ± 0.22 ) x 10

-12

( 1.61 ± 0.07 ) x 10

-11
-10
-10
-10
-9
-9
-9
-9

counter.
profiles of

36

1

shows

Cl /

35

the

depth
-8

10

0

10

-1

-10

10

-2

-11

10

-3

10

Cl ratios together
Cl / Cl

with the specific radioactivities of 152Eu,
Co, 3H, 22Na and 54Mn in the shieldingThe

36

concrete of the ring cyclotron.

35

60

maximum 36Cl / 35Cl ratio was observed

-9

10
10

Activity (Bq/g)

Fig.

at about 10 cm in depth from the surface,
and the depth profile of 36Cl / 35Cl ratios

10

was good agreement with those of 152Eu
60

Co, and 3H.

These characteristics

0

10

20
30
Depth (cm)Fig. 1 Depth profiles of 36Cl / 35Cl ratios( ) and specificwere common to the AVF cyclotron, theradioactivities of 152Eu (electron

22

synchrotron

accelerator facilities[2].
imply that

and

other

These results

36

Cl formed in concrete of

40

Na (

) and 54Mn (), 60Co (), 3H (),) induced in the shielding concreteof ring cyclotron ( Research Center for Nuclear Physics,
Osaka University )these accelerators is mainly formed bythermal neutron capture of 35Cl. The 36Cl / 35Cl directly shows the specific activity and 36Cl is a very
long half-life nuclides. Therefore the 36Cl / 35Cl measurement is more suitable for the monitoring of
cumulative thermal neutron fluence than the radioactivity measurement of 152Eu and 60Co.
References[1] T. Miura et al., J. Nucl. Sci. Technol.,Sup.1 (2000)183[2] K. Bessho et al., UTTAC-71 (2002) 99[3] Y. Nagashima et al., Nucl. Instr. Meth. B172(2000)129[4] R. Seki et al., J. Radioanal. Nucl. Chem. 255(2003) 245- 74 -AMS measurement of the 14N(16O,α)26Al reaction at the near barrierenergies

4.6

H. Ming1, Y. Nagashima, K. Sasa, R. Seki, T. Matsuhiro, T. Takahashi, Y. Tosaki, and K. Sueki
The 1.809MeV γ-line due to the decay of 26Al has been observed in the interstellar medium in
1980s. Since the 26Al half-life (3×106 yr) is much shorter than the time-scale of the galactic evolution(~109 yr), the detection of this radioactivity shows that the nucleosynthesis is still active in our Galaxy.
Many models have been proposed to explain the source of the 1.809MeV γ-ray, but the origin is still
remaining as a mystery in astrophysics. The 14N(16O,α)26Al reaction might be one of the source of
1.809MeV γ-ray in the interstellar medium during the supernova explosion such as SNIa. Therefore, the14

N(16O,α)26Al reaction cross sections have been measured by using the prompt γ-ray detection method.

However, Due to the small cross sections at low stellar temperatures (T9=0.06~0.2) and resulting
extremely low counting rate, there are no reliable data of this reaction at sub-barrier energy now.
Here, we report an AMS measurement as an alternative method for the determination of the14

16

N( O,α)26Al reaction cross section. The high sensitivity of the AMS is very efficient for the detection ofvery rare element and allows the determination of radioisotope concentrations such as 26Al at the level
down to 10-15 of 26Al to 27Al ratio. The 26Al elements have been created through 14N(16O,α)26Al reaction at
three incident energies, Ec.m.=9.5, 7.9, and 6.6 MeV. The irradiation is performed at the tandem
accelerator laboratory in the Peking University. TiN foil being evaporated on the high-purity Cu backing
foil is used as a 14N target. A 20µm thick Cu foil is selected as the backing foil and that is thick enough tocatch not only 16O beams but also 26Al and 14N recoils. The thickness of the evaporated TiN is comparably
thick and its thickness is precisely estimated by comparing the weight of before and after the evaporation.
The total amount of 16O dose is also carefully measured with an ORTEC current integrator, see Table 1.
Fig. 1 shows the arrangement of the TiN target in an insulated chamber with an electrode for electron
suppress. Thus, the chamber is functioned not only as a target chamber but also as a Farady-cup for themeasurement of the total dose of the 16O impinging beam. The TiN target with Cu backing is tightly fixed
to a bottom of the chamber in order to keep a nice heat conductivity. To prevent an extremely rise of thetarget temperature, the chamber is continuously cooled down by cooling water and the target is kept to lowtemperature during the one day bombardment with 3µA 16O accelerated beam. Both size and shape of the16

O beam on the target was monitored by exchange the target housing for a quartz housing. This

monitoring has been repeated every ~3 hours in order to confirm the 16O beam qualities. The beam wasvery stable and there was no observation in beam deterioration. Accounting into both the sensitivity of
26

Al-AMS measurements, 26Al/27Al=~10-15, and the smallest required amount of 27Al carrier, ~2mg, ~106

atoms of 26Al must be produced in the bombardment. So, in the case of the lowest bombarding energy(6.6MeV), the target was irradiated for 3 days by ~ 2µA 16O beam.
The procedures for extracting the 26Al elements from the TiN target material are followings. First,

1

Present address: China Institute of Atomic Energy- 75 -

both of the TiN target and 27Al carrier that is measured precisely are dissolved into nitrohydrochloric acidsolution, HNO3 + HCl. Then, the solution is diluted to be 0.1M and condensed ammonium regent is mixed
into the solution little by little in order to precipitate Al element as an aluminum hydroxide, AlOH. The
centrifugation and washing the precipitate are repeated several times. At this step, all most ofcontaminants such as Cu are separated out from the AlOH precipitate. Finally, the AlOH precipitate aredried and then it is changed to Al2O3 by heating up to 1000°C for two hours.
26

Al contents in three Al2O3 samples, which are produced through 14N + 16O fusion reactions, aremeasured by means of AMS. The Al2O3 samples are mixed with powder of pure silver and an amount ofenriched 26MgO regent. The purposes of the silver and 26MgO addition are to keep an electronic
conductivity and to create 26MgO- control beam for the tandem voltage stability, respectively. Both 26Al7+
and 26Mg7+ with 78MeV energy are selected by the 90° analyzing magnet and are transported into the 2nd
charge exchange foil. After passing through the foil, 26Al13+ fully stripped ions are selected by thefollowing energy and momentum selectors and are forwarded to the ∆E-E ionization counter in the AMS
beam line. We measure the standard samples before and after sample measurement, with one set consistingof three measurements: measurement of standard sample - measurement of a sample - measurement of astandard sample. We conduct four sets of measurements for each sample to obtain average value. Thoughdependent on the 26Al concentration of the samples, one set of measurement require 40 - 60 min. The
measurements are still undergoing.

- 76 -

Bombarding
energy (Ec.m.,
MeV)

Dose of 16O beam(C)

TiN thickness(µg/cm2)

9.5

6.47×10-3

317

5.8

7.9

3.63×10-2

260

3.9

6.6

4.72×10-1

280

2.8

Table 127

Al carrier added(mg)

List of samples. TiN targets are evaporated on the pure Cu backing foils.

The bombarded target together with an Al carrier is dissolved into dense solutionof HNO3 and HCl mixture. The chemical pure Al regent is used as an Al carrier.

Fig .1

Cross section of the bombarding chamber. TiN foil on the Cu backing is set
on the bottom of the chamber. The chamber is cooled continuouslywith the drop of water.

- 77 -

4.7

Qualitative measurement of hydrogen depth profile by using ERCS
for melt inclusions in quartz crystal

T. Komatsubara, K. Sasa, S. Ishii, Y. Yamato, K. Miyakawa, T. Kurosawa, K. Furuno
Proton-proton elastic recoil coincidence spectrometry (ERCS) is powerful method to analyze hydrogen content[1]. This analysis is quite convenient and non-destructive. It is also possible to deduce depth
profile of hydrogen content. New project by using this spectrometry has been started at Tandem Accelerator Center, University of Tsukuba, combined with the micro beam system[2, 3]. In this report, our recent
developments for the hydrogen analysis in melt inclusions of mineral samples will be described.
For the analysis of the mineral samples, positioning of the irradiation point is quite important. Typicalsize of the quartz sample is about 3 mm in diameter. The thickness of the sample is 0.2 mm or less. As
our object of the analysis, the quartz samples contain several melt inclusions that size are in range from 30- 300 µ m. In the micro beam irradiation system, micro scope has been installed to observe the irradiation
point. For more clear view of the target, two thin mylar films were used to hold the samples in vacuum.
Aluminium foils of 5 mm in thickness were used to shade particle detectors, as the observation is possible
during the irradiation measurements.
Since the mylar films contain hydrogen, the scattering yields from these supporting films are alsoavailable for the calibration. Scattering yield Y [counts] can be calculated as
dσ
ΩQw
dΩ
where difference cross section is denoted by dσ /dΩ in mb/sr, solid angle of detector is Ω sr, and irradiation
Y = 3.759

charge is Q in nano Coulomb. Target thickness is given by w µ g/cm2 [H] as the corresponding hydrogenweight density. Weight ratio of the contained hydrogen in the mylar film was measured to be 4.49 ± 0.03
wt.%[H] by using CHN trace element analysis. Thickness of the films is measured to be 348 ± 3 µ g/cm2 .
The mylar films were purchased from Chemplex Industries Inc. and nominally described as 2.5 µ m inthickness. This hydrogen density corresponds to 15.6 ± 0.2 µ g/cm2 [H] as the hydrogen target thickness.
Scattering yield from one mylar film is measured to be 2722 ± 17 counts for 50 nano Coulomb irradiation.
Solid angle of the coincidence system is calculated to be 0.0156 sr which is defined by the detector slits of

φ 5.4 in diameter at 38 mm from the scattering center. The differential cross section is deduced to be 59.5
± 0.7 mb/sr in laboratory frame which corresponds to 21.0 ± 0.3 mb/sr in center of mass. This measured
value is rather consistent to singles measurement as dσ /dΩ = 24.6 ± 0.3 mb/sr at 19.8 MeV [4].
If the irradiation power is strong, some hydrogen could be emitted out from the target or the supporting
mylar films. If the irradiation damage occurs, power density should be reduced by decreasing beam
current. In Fig. 1a, the variation of the scattering yields is shown when the same position of the mylar
film was irradiated by 130 pA of φ 30 µ m micro beam. This figure shows slight decrease of the scattering
yield. The reduction in a 50 n Coulomb irradiation measurement can be estimated as 1.2 %. Kapton filmshows more persistent than the mylar film shown in the Fig. 1b. However, yellow color of the kapton film
gives worse transparency than mylar. We have chosen mylar films as the supporting films for more clear
micro scope view.

- 78 -

As reported in the previous annual report a solid angle for the coincidence experiment strongly depends
on the irradiation position. With simple assumption, the solid angle depending on the displacement along
to beam direction (z axis) can be calculated as following formula.
2θ r2 − |z| 2r 2 − |z|2
Ω=
d2
|z|
θ = Arccos √2rwhere r denotes a radius of collimators in front of the detectors and d is a distance between the collimators
and a target. These formula are identical to the previous report.
For more detail dependence on the displacements, computer simulation was performed. As the resultof the calculation, detection solid angle with coincidence condition exhibits strong dependence on y direction and less sensitive to x direction, as shown in Fig. 2(a), (b) and (c). When displacements occur for two
directions simultaneously, solid angle varies smoothly at Z=0 position as shown in Fig. 2(d) and (e). In
these calculations, the present geometry of φ 5.4 mm slits at 38 mm from an irradiation point is assumed.
For the ERCS method, a measured spectrum of sum energy of two protons implies depth profile ofhydrogen, because stopping powers for the scattered protons are twice higher than that of incident proton.
Therefore, the measured sum energy spectrum can be modified to be depth profile of hydrogen. If one
consider to reconstruct the hydrogen profile from the measured sum energy spectrum, there are several
effects which should be taken into account; those are stopping power, secondary scattering, multiple
scattering, lateral and longitudinal straggling, variation of material, and displacement.
In order to evaluate the effect of the stopping power, computer simulation were performed. Calculated
sum energy spectra of scattered particles which are degraded by the stopping power are shown in Fig.
3(a). The data of stopping power is referred from SRIM table. Targets are assumed to be SiO2 with ahomogeneous hydrogen content. Thickness of the SiO2 plates are 100, 200, 300, and 400 µ m. The sum
energy depends on the position of the scattering in depth, however, the dependence is not linear. For thereconstruction of the constant hydrogen density, a quadrant term is introduced to convert a channel x as
follows;x = C0 +C1 × (x −C0 ) +C2 × (x −C0 )2
where x is a new channel number to indicate depth position. By using the two parameters as C1 = 1.0 and
C2 = 9.56 × 10−4 , modified spectra show rather constant hydrogen densities as shown in Fig. 3(b).
As a realistic example of the data, a measured sum spectrum of a multi-layer sample is shown in Fig.
4(a). At first, channel number is modified as described above as shown in Fig. 4(b). For the compensationof the exponential decrease by the secondary scattering, measured counts are multiplied asY  (x ) = Y (x ) × eµ (C0 −x )where the parameter µ can be obtained from scattering yields and peak positions of two mylar films on
the surfaces. In Fig. 4(c) the modified spectrum is shown as hydrogen profile.

- 79 -

References[1] B.L. Cohen, C.L. Fink, J.H. Degnan, J. Appl. Phys., 43, 19 (1972).
[2] K. Sasa, H. Oshima, Y. Yamato, T. Komatsubara, T. Katabuchi, K. Shima, K. Furuno, M. Kurosawa,
N. Yanagisawa, Nucl. Inst. Meth. B190, 287 (2002).
[3] K. Furuno, T. Komatsubara, K. Sasa, H. Oshima, Y. Yamato, S. Ishii, H. Kimura, M. Kurosawa,
Nucl. Inst. Meth. B210, 459 (2003).
[4] J.W. Burkig, J.R. Richardson, G.E. Schrank, Phys. Rev. 113, 290 (1959).

- 80 -

4000

(a)
Yield

3000

2000

sample : mylar film
1000

0

0

100

200

300

400

500

8000

(b)
Yield

6000

4000

sample : kapton film
2000

0

0

100

200

300

400

500

Irradiation charge [nC]Fig. 1(a) Scattering yields from the same position of mylar film. By repeating measurements, slightly
decrease of the yield was observed. Fig. 1(b) Repeated measurements with kapton film. The kapton film

20
20

10
5
0

−20

−10

0

10

20

solid angle [msr]x direction [mm]

(d)

dx=0
15

dx=4mm10

dx=8mm

5

20
0
−6

(b)

15

−2

0

2

4

6

20

10
5
0

−4

z direction [mm]

−6

−4

−2

0

2

4

6

y direction [mm]solid angle [msr]solid angle [msr]

(a)

15

20

(c)

15

solid angle [msr]solid angle [msr]shows more persistence.

dy=0.5mm
10dy=1.0mm
dy=1.5mm

5

0
−6

10

(e)

dy=0

15

−4

−2

0

2

4

6

z direction [mm]
5
0

−6

−4

−2

0

2

4

6

z direction [mm]Fig. 2. Calculated solid angles by changing irradiation position. Figs. 2(a), 2(b) and 2(c) show calculated
solid angles depending on the position moving along to x-, y- and x- directions, respectively. Whendisplacements occur for x and z directions at same time, solid angle is not maximum at dz = 0 position asshown in Fig. 2(d). Combination of the displacement for y- and z- directions show more serious
reduction of the solid angle as shown in Fig. 2(e).

- 81 -

1400

100 micro hydrogen in SiO2 (a)200 micro

Counts/Channel

1200
1000

300 micro
400 micro

800
600
400
200
0
1400

0

Counts/Channel

1200

20

40

60

80

100

(b)

Channel ismodifiedto be
thickness

1000
800

120

600
400
200
0
0

20

40

60

80

100

120

ChannelFig. 3(a) Simulated spectra of sum energy for the proton-proton coincidence measurement by using
calculation of stopping power for incident and scattered protons. Hydrogen density is assumed to beconstant in SiO2 of 100, 200, 300 and 400 µ m in thickness. Channel number is equal to be 5 × sum
energy in MeV. Fig. 3(b) is results of the modification from the sum energy spectra. A Method of theanalysis is described in text.
600

map736.nov2003.xy.comp.depth

400

Sum energy spectrum(a)Channel is modified
to become thickness(b)Counts are modified
as hydrogen density(c)Counts/Channel

200
0
400
200
0
400
200
0
300

400

500

600

700

800

ChannelFig. 4(a) Measured spectrum for a stacked target which consists five mylar of 2.5 µ m in thickness and
SiO2 glass of 50 µ m. Fig. 4(b) shows the result of the modification described in text. The modified
channel number can correspond depth position. Fig. 4(c) is the result of correction for exponential decayof the scattering yield reduced by the secondary scattering.

- 82 -

4.8

High energy gamma rays from radiative capture reactions

T. Komatsubara, M. Yamaguchi, A. Maki1 , T. Haruyama1 , T. Iwamoto2 , S. Mihara2 , H. Nishiguchi 2, Y.
Hisamatsu 2 , W. Ootani2 , K. Ozone2 , R. Sawada2 , T. Mitsuhashi 2
1 High Energy Accelerator Research Organization
2 International Center for Elementary Particle Physics, University of Tokyo

A radiative capture process is known as a gamma-ray transition from a unbound scattering state to abound state. This reaction can be considered as a two-step process where a intermediate state is excitedby the nuclear reaction at first and de-excitation process follows by the electromagnetic interaction [1].
However reaction cross section of this process is rather small, energy of the emitted gamma rays can bereached to be more than 20 MeV. New project with large xenon scintillation detector system has been
started to seek µ → eγ decay mode emitting a 52.6 MeV photon as collaboration with PSI and KEK[3].
For the development of the high energy gamma ray detectors, high energy photon sources are desired forthe precise calibration.
A nuclear reaction of 11 B(p,γ ) 12C is considered for the test experiment providing a high energy
gamma ray by the radiative capture reaction. A gamma-transition was reported from E ∗ = 22.6 MeV with
Γc.m. = 3.2 MeV as a giant resonance in the 12 C[4]. However, better resolution of 380keV (FWHM) was
reported by using thin target of 400 µ g/cm2 in thickness [2]. Reaction cross sections was reported asdσ /dΩ(90◦ ) = 13.1 ± 1.3 µ b/sr at the bombarding energy of 7.2 MeV for the proton beam [4].
The test experiment has been performed by the proton beam irradiated on some compound material
targets including boron powder. Bombarding energy of the proton beam is 7.2 MeV. Gamma ray spectra
were measured by a 5’ × 5’ NaI scintillator surrounded by four veto counters to eliminate back groundof cosmic rays. Fig. 1 shows the measured spectrum in which several high energy peaks appear around
20 MeV. However, rather similar spectrum is observed for another target without boron powder shown in
Fig. 2. The origin of these peaks are under consideration.

- 83 -

Fig. 1. Gamma-ray spectrum obtained by the irradiation of 7.2 MeV proton beam on the compound material including boron powder. Gamma-rays were measured by by 5’ × 5’ NaI scintillation detector
surrounded by four veto counters.

Fig. 2. Gamma-ray spectrum obtained by another target which does not contain boron.

References[1] H. Ejiri and M.J.A de Voigt, ”Gamma-ray and electron spectroscopy in nuclear physics”, Oxford
science publications, Clarendon Press, Oxford, (1989).
[2] A. H åkansson, J. Blomgren, S. Crona, A. Likar, A. Lindholm, L. Nilsson, N. Olsson, R. Zorro,
Nucl. Inst. Meth. A273, 211, (1988).
[3] T. Doke, T. Haruyama, T. Ishida, A. Maki, T. Mashimo, S. Mihara, T. Mitsuhashi, T. Mori, H.
Nishiguchi, W. Ootani, S. Orito, K. Ozone, R. Sawada, S. Suzuki, K. Terasawa, M. Yamashita, J.
Yashima, T. Yoshimura, Nucl. Inst. Meth. A505,199, (2003).
[4] F. Ajzenberg-Selove, Nucl. Phys. A433, 1, (1985).

- 84 -

5. LIST OF PUBLICATIONSNUCLEAR PHYSICS – EXPERIMENT
M. Yamaguchi, K. Sawada, T. Katabuchi, N. Kawachi, N. Yoshimaru, K. Shiga and Y. Tagishi Highefficiency polarimeter for a secondary proton beam of 16-22 MeV Nucl. Inst. and Meth. A 506,
35-40, (2003).
H.Miyatake, H.Ueno, Y.Yamamoto, N.Aoi, K.Asahi, E.Ideguchi, M.Ishihara, H.Izumi, T.Kishida,
T.Kubo, S.Mitsuoka, Y.Mizoi, M.Notani, H.Ogawa, A.Ozawa, M.Sasaki, T.Shimoda, T.Shirakura,
N.Takahashi, S.Tanimoto, and K.Yoneda, Spin-parity assignments in 15C∗ by a new method: β delayed spectroscopy for a spin-polarized nucleus, Phys. Rev. C 67, 014306 (2003).
A.Ozawa, Y.Yamaguchi, M.Chiba, R.Kanungo, K.Kimura, S.Momota, T.Suda, T.Suzuki, I.Tanihata,
T.Zheng S.Watanabe, T.Yamaguchi, and K.Yoshida, Search for 21 B, Phys. Rev. C 67, 014610 (2003).
A.A.Korsheninnikov, E.Yu.Nikolskii, E.A.Kuzmin, A.Ozawa, K.Morimoto, F.Tokanai R.Kanungo,
I.Tanihata, N.K.Timofeyuk, M.S.Golovkov, A.S.Fomichev, A.M.Rodin, M.L.Chelnokov, G.M.TerAkopian, W.Mittig, P.Roussel-Chomaz, H.Savajols, E.Pollacco, A.A.Ogloblin, M.V.Zhukov, Experimental evidence for the Existence of 7 H and for a Specific Structure of 8 He, Phys. Rev. Let. 90,
082501 (2003).
D.Cortina-Gil, J.Fernandez-Vazquez, F.Attallah, T.Baumann, J.Benlliure, M.J.G.Borge, L.V.Chulkov,
C.Forssen, L.M.Fraile, H.Geissel, J.Gerl, K.Itahashi, R.Janik, B.Jonson, S.Karlsson, H.Lenske, S.Mandal,
K.Markenroth, M.Meister, M.Mocko, G.Munzenberg, T.Ohtsubo, A.Ozawa, Yu.Parfenova, V.Pribora,
A.Richter, K.Riisager, R.Schneider, H.Scheit, G.Schrieder, N.Shulgina, H.Simon, B.Sitar, A.Stolz,
P.Strmen, K.Summerer, I.Szarka, S.Wan, H.Weick, M.Zhukov, Nuclear and Coulomb breakup of 8 B,
Nucl. Phys. A 720, 3-19 (2003).
F.Schümann, F.Hammache, S.Typel, F.Uhlig, K.Sümmerer, I.Böttcher, D.Cortina, A.Förster, M.Gai,
H.Geissel, U.Greife, N.Iwasa, P.Koczon, B.Kohlmeyer, R.Kulessa, H.Kumagai, N.Kurz, M.Menzel,
T.Motobayashi, H.Oeshler, A.Ozawa, M.Ploskon, W.Prokopowicz, E.Schwab, P.Senger, F.Strieder,
C.Sturm, Zhi-Yu Sun, G.Surowka, A.Wagner, and W.Walus, Coulomb Dissociation of 8B and the
Low-Energy Cross Section of the 7 Be(p,γ )8 B Solar Fusion Reaction, Phys. Rev. Let., 90 232501(2003).
S.Nishimura, M.Kurata-Nishimura, K.Morimoto, Y.Nishi, A.Ozawa, T.Yamaguchi, T.Ohnishi, T.Zheng,
M.Chiba, I.Tanihata, Systematic studies of scintillation detector with timing resolution of 10 ps forheavy ion beam, Nucl. Instr. Meth. A 510, 377-388 (2003).
T.Yamaguchi, T.Zheng A.Ozawa, M.Chiba, R.Kanungo, T.Kato, K.Katori, K.Morimoto, T.Ohnishi,- 85 -

T.Suda, I.Tanihata, Y.Yamaguchi, A.Yoshida, K.Yoshida, H.Toki, N.Nakajima, Momentum distributions of 14 C and 15 C fragments from 16 C breakup, Nucl. Phys, A 724 3-13 (2003).
T.Baumann, H.Ikeda, M.Kurokawa, M.Miura, T.Nakamura, Y.Nishi, S.Nishimura, A.Ozawa, T.Sugimoto,
I.Tanihata, M.Thoennessen, Using passive converters to enhance detection efficiency of 100-MeV
neutrons, Nucl. Instr. and Meth. A 505, 25-28 (2003).
R.Kanungo, M.Chiba, S.Adhikari, D.Fang, N.Iwasa, K.Kimura, K.Maeda, S.Nishimura, Y.Ogawa,
T.Ohnishi, A.Ozawa, C.Samanta, T.Suda, T.Suzuki, Q.Wang, C.Wu, Y.Yamaguchi, K.Yamada, A.Yoshidaa,
T.Zheng, I.Tanihata, Possibility of a two-proton halo in 17 Ne, Phys, Lett. B 571 21-28 (2003).
L.S.Geng, H.Toki, A.Ozawa and J.Meng, Proton and neutron skins of light nuclei within the relativistic mean field theory, Nucl. Phys., A 730, 80-94 (2003).
C.Y. Xie, X.H. Zhou, Y. Zheng, Y.H. Zhang, Z. Liu, Z.G. Gan, T. Hayakawa, M. Oshima, T. Toh, T.
Shizuma, J. Katakura, Y. Hatsukawa, M. Matsuda, H. Kusakari, M. Sugawara, K. Furuno, T. Komatsubara, Level structure of Tb-146, Eur. Phys. J. A 19, pp. 7-9 (2004).
C.B. Moon, T. Komatsubara, K. Furuno, Band structures in I-116, Nucl. Phys. A 730, pp.3-22 (2004).
Y.H.Zhang, M.Oshima, Y.Toh, X.H.Zhou, M.Koizumi, A.Osa, A.Kimura, Y.Hatsukawa, T.Morikawa,
M.Nakamura, M.Sugawara, H.Kusakari, T.Komatsubara, K.Furuno, H.L.Wang, P.Luo, C.S.Wu, F.R.Xu,
Rotational bands and signature inversion in odd-odd 172Re, Phys.Rev. C 68, 054313 (2003).
C.B. Moon, T. Komatsubara, T. Shizuma, Y. Sasaki, K. Furuno, C.S. Lee, Collective bands in oddodd 118I, Nucl. Phys. A728, pp.350-364 (2003).
C.-B.Moon, T.Komatsubara, K.Furuno, A Dipole Band in 122Xe, Journal of the Korean Physical Society 43, pp.574-577 (2003).
C.B. Moon, T. Komatsubara, K. Furuno, Collective bands in 115I, Journal of the Korean PhysicalSociety 43, pp.319-324 (2003).
Y.H. Zhang, F.R. Xu, J.J. He, Z. Liu, X.H. Zhou, Z.G. Gan, M. Oshima, T. Hayakawa, Y. Toh, T.
Shizuma, J. Katakura, Y. Hatsukawa, M. Matsuda, H. Kusakari, M. Sugawara, K. Furuno, T. Komatsubara, T. Une, S.X. Wen, Z.M. Wang, High-spin states and signature inversion in odd-odd Au-182,
Science in China Series G-Physics Astronomy 46, pp.382-389 (2003).
Z. Liu, Y.H. Zhang, Y.J. Ma, Y. Sasaki, K. Yamada, H. Oshima, H. Yokose, M. Ishizuka, T. Komatsubara, K. Furuno, High-spin states of Sb-125: Particle-core excitation coupling, Science in China
Series G-Physics Astronomy 46, pp.390-397 (2003).

- 86 -

K. Sasa, K. Furuno, Y. Yamato, H. Ohshima, S. Ishii T. Komatsubara, M. Kurosawa, The Tsukuba
high-energy nuclear microprobe for hydrogen analysis of mineral samples, Nucl. Instr. and Meth.
B210, 48-53 (2003).
K Furuno, T. Komatsubara, K. Sasa, H. Ohshima, Y. Yamato, S. Ishii, H. Kimura, M. Kurosawa,Measurement of hydrogen concentration in thick mineral or rock samples, Nucl. Instr. and Meth.
B210, 459-463 (2003).
K. Sasa, K. Shima, T. Komatsubara, H. Kudo, Applied research by the 12MV tandem accelerator andthe 1MV tandetron accelerator, Genshikaku Kenkyu, Vol.48, No.5, 43-52 (2003).
HIGH ENERGY NUCLEAR PHYSICS
T. Abbott, Y. Miake, et al., Further observations on midrapidity et distributions with aperture corrected scale, Phys. Rev. C68 :034908, (2003).
M. Aizawa, S. Esumi, Y. Miake, et al., PHENIX central arm particle id detectors, Nucl. Instrum.
Meth. A499 :508-520, (2003).
K. Adcox, S. Esumi, Y. Miake, et al., PHENIX detector overview, Nucl.Instrum.Meth.A499 :469479, (2003).
S. Nikolaev, Y. Miake, et al., Photon flow in 158-A-GeV Pb + Pb collisions, Nucl.Phys.A715:579582, (2003).
S.S. Adler, S. Esumi, Y. Miake, et al., Absence of suppression in particle production at large transverse momentum in s(NN)**(1/2) = 200-GeV d + Au collisions, Phys.Rev.Lett.91:072303, (2003).
A. Drees, S. Esumi, Y. Miake, et al., Heavy ion collisions at collider energies: insights from PHENIX,
Pramana 60:639-650, (2003).
S.S. Adler, S. Esumi, Y. Miake, et al., Suppressed π 0 production at large transverse momentum incentral Au + Au collisions at s(NN)**1/2 = 200 GeV, Phys.Rev.Lett.91:072301, (2003).
Bedangadas Mohanty, Y. Miake, et al., Particle density fluctuations, Nucl.Phys.A715:339-348, (2003).
K. Adcox, S. Esumi, Y. Miake, et al., Centrality dependence of the high p(t) charged hadron suppression in Au+Au collisions at s(NN)**(1/2) = 130-GeV, Phys.Lett.B561:82-92, (2003).
M.M. Aggarwal, Y. Miake, et al., Centrality dependence of charged neutral particle fluctuations in- 87 -

158-A-GeV Pb-208 + Pb-208 collisions, Phys.Rev.C67:044901, (2003).
S.S. Adler, S. Esumi, Y. Miake, et al., Mid-rapidity neutral pion production in proton proton collisions at S**(1/2) = 200-GeV, Phys.Rev.Lett.91:241803, (2003).
S.S. Adler, S. Esumi, Y. Miake, et al., Elliptic flow of identified hadrons in Au+Au collisions ats(NN)**(1/2) = 200-GeV, Phys.Rev.Lett.91:182301, (2003).
S.S. Adler, S. Esumi, Y. Miake, et al., Scaling properties of proton and anti-proton production ins(NN)**(1/2) 200-GeV Au+Au collisions, Phys.Rev.Lett.91:172301, (2003).
D. Adamova, S. Esumi, et al., Event by event fluctuations of the mean transverse momentum in 40,
80 and 158 A GeV/c Pb - Au collisions, Nucl.Phys.A727, 97-119, (2003).
D. Adamova, S. Esumi, et al., Enhanced production of low mass electron pairs in 40-AGeV Pb+Au
collisions at CERN SPS, Phys.Rev.Lett.91, 042301-042305 (2003).
D. Adamova, S. Esumi, et al., Universal pion freezeout in heavy ion collisions, Phys.Rev.Lett.90,
022301-022305, (2003).
D. Adamova, S. Esumi, et al., Beam energy and centrality dependence of two pion Bose-Einsteincorrelations at SPS energies, Nucl.Phys.A714, 124-144, (2003).
ATOMIC AND SOLID STATE PHYSICS, AND CLUSTER SCIENCE
I. Arai , S. Shimakura, K. Hino, T. Miyazaki and S.-M. Lee, Secondary Electron Emission fromCu Surface by Bombardment of Cu Cluster Ions, Transactions of the Materials Research Society ofJapan, 28, 859-862, (2003).
K. Teranishi, T. Miyazaki, I. Arai and S.-M. Lee, Cluster Abundance Spectra of Low Melting Temperature Metals Produced by Bombardment of 6 keV Xe Atoms, Transactions of the Materials ResearchSociety of Japan, 28, 863-866, (2003).
J.A. Macdonald, I. Arai, et al., Apparatus for a search for T-violating muon polarization in stoppedkaon decays, Nucl. Instr. and Meth., A506, 60-91, (2003).
E. Takayama-Muromachi, T. Drezen, M. Isobe, N.D. Zhigadlo, K. Kimoto, Y. Matsui, E. Kita, New
ferromagnets of Sr8 ARe3 Cu4 O24 (A=Sr, Ca) with an ordered perovskite structure, J. Solid. State
Chem. 175 94-103, (2003).
H. Kudo, K. Takeda, T. Suguri, W. Iwazaki, C. Sakurai, I. Arano, S. Numazawa, Electron loss from- 88 -

fast partially-stripped C and O ions incident on crystal targets, S. Seki, Nucl. Instrum. and Methods
B207, 283-290, (2003).
M. Onoda and I. Amemiya, Quasi-one-dimensional polaronic states due to the preferential reductionin the Li1+x V3 O8 insertion electrode, J. Phys.: Condens. Matter, Vol. 15, No. 19, pp. 3079-3093(2003).
U. Manju, S. R. Krishnakumar, S. Ray, S. Raj, M. Onoda, C. Carbone and D. D. Sarma, Electron
spectroscopic investigation of metal-insulator transition in Ce1−x Srx TiO3 , Proc. Indian Acad. Sci.
(Chem. Sci.), Vol. 115, No. 5 & 6, pp. 491-498 (2003).
K. Okazaki, H. Wadati, A. Fujimori, M. Onoda, Y. Muraoka and Z. Hiroi, Photoemission study ofthe metal-insulator transition in VO2 /TiO2 (001): Evidence for strong electron-electron and electronphonon interaction, Phys. Rev. B Vol. 69, pp. 165104-1 - 165104-7 (2004).
Changqing Li, K.Kondo, T.Makimura and K.Murakami, Increase of 1.5mm luminescence from cryogenic temperature to room temperature from Er-doped SiO2 films with Si nanocrystallites fabricatedby laser ablation, Jpn. J. Appl. Phys. 42, 3432 (2003).
T.Makimura, K.Kondo, H.Uematsu, C.Li and K.Murakami, Optical excitation of Er ions with 1.5mm
luminescence via the luminescent state in Si nanocrystallites embedded in SiO2 matrices, Appl. Phys.
Lett. 83, 5422 (2003).
H.Uematsu, K.Kondo, Changqing Li, T.Makimura and K.Murakami, Optical excitation bands of Er
doped SiO2 films with Si nanocrystallites and energy transfer mechanism to Er ions, 6th Int. Symp.
on photoreaction control and photofunctional materials, Oct. 2003, Tsukuba, P-47, (2003).
M. Kurosawa, S. Shimano, K. Shima, S. Ishii, T. Nakajima and T. Kato, Quantitative PIXE Analysis
of Single Fluid Inclusions in Quartz Vein: Chemical Composition of Hydrothermal Fluids Related toGranite, Nucl. Instrum. and Methods B210 :464-467, (2003).
K. Awazu, S. Ishii, K. Shima, S. Roorda, and J.L. Brebner, Structure of Latent Tracks Created by
Swift Heavy-ions of Amorphous SiO2 and Zinc Phosphate Glass, Jpn. J. Appl. Phys. 42:3950-3957,(2003).
K. Nomura, T. Nakanishi, Y. Ohki, K. Awazu, M. Fujimaki, S. Ishii and K. Shima, Structural change
induced in TiO2 by swift heavy ions and its application to three-dimensional lithography, Phys. Rev.
B 68:064106-1-064106-8, (2003).
M. Kurosawa, S. Shimano, K. Shima, S. Ishii, and T. Kato, Quantitative trace element analysis ofsingle fluid inclusions by proton-induced X-ray emission (PIXE): application to fluid inclusion in- 89 -

hydrothermal quartz, Geochimica et Cosmochimica Acta. 67:404-419, (2003).
H. Tanimoto, T. Yamada, and H. Mizubayashi, Characteristic Mechanical Properties of High-Density
Nanocrystalline Gold, Proc. of Int. Conf. on Advanced Technology in Experimental Mechanics 2003
(ATEM’03), Nagoya Congress Center, Nagoya, Japan, 10-12 Sept., 2003, ed. by Y. Akiniwa et al.,OS06W0396(6pages).
H. Tanimoto, N. Yagi, T. Yamada, and H. Mizubayashi, Characterization and Mechanical Properties
of High-Density Nanocrystalline Copper, Proc. of Int. Conf. on Advanced Technology in Experimental Mechanics 2003 (ATEM’03), Nagoya Congress Center, Nagoya, Japan, 10-12 Sept., 2003,
ed. by Y. Akiniwa et al., OS06W0399(6pages).

6. THESES
Ph. D. Theses
Kenichiro SatouAn experimental study of shell effects of interacting nuclei
on heavy-ion fusion reactions

M. Sc. Theses
Shigeto Kaminaga
Masahiro Konno
Hideyuki Arai
Satoshi Takagi
Masanori Kubo
Naoko Yoshimaru
Maya Shimomura
Yasushi Takanashi
Hiroyuki Ishiguro
Takahiro Suzuki
Masaru Nagata√
Identified hadron spectra in p+p collisions at s NN=200GeVDevelopment and construction of aerogel Cherenkov detector
for the RHIC-PHENIX experiment
Effect of negatively biased disc to electron cyclotron
resonance plasma
Simulation study for aerogel Cherenkov counterat RHIC-PHENIX
Absorption of silicon atoms on gold clusters
The 6 Li(d,p)7 Li reaction with polarized deuterons at anincident energy of 90keVHigh pT charged hadron analysis in 200 GeV Au+Au collisions
at RHIC-PHENIXInteraction of highly charged ion with matter
Measurement of energy dependence of total reaction cross sectionof 12 C+p system around (p,n) threshold energy
Collision-induced nonlinear ionization by MeV atom clusters
Resonant coherent excitation observed with electrons lost from fast ions

- 90 -

7. SEMINARS
Date
2003
April
June

Title and Speaker
23
4

Oct.

8

Nov.

12

Nov.

19

Dec.

17

Dec.

24

2004
Jan.

14

Jan.

21

Jan.

28

Feb.

25

Mar.

31

Physics for unstable nuclei; A. Ozawa (Osaka Univ.)
The mysterious neutral particle, does it really exist ?;M. Sakai (Tokyo Univ.)
Perspectives of characterization of semiconductor devices by using highintensity slow positron beam; A. Uedono (Univ. of Tsukuba)
Structure of latent tracks in titanium dioxide created by swift heavy ionsand micro-fabrication using ion beams K. Awazu (AIST)RI beam factory project in RIKEN and storage ring;
A. Ozawa (Univ. of Tsukuba)
An experimental study of shell effects of interacting nuclei
on heavy-ion fusion reactions; K. Satou (Univ. of Tsukuba)
Identified hadron spectra in p+p collisions at√
s NN=200GeV; Y. Kaminaga (Univ. of Tsukuba)
Development and construction of aerogel Cherenkov detector
for the RHIC-PHENIX experiment; M. Konno (Univ. of Tsukuba)
Effect of Negatively Biased Disc to Electron Cyclotron Resonance Plasma;
H. Arai (Univ. of Tsukuba)
Simulation study for Aerogel Cherenkov Counter at RHIC-PHENIX;
T. Takagi (Univ. of Tsukuba)
Absorption of silicon atoms on gold clusters; M. Kubo (Univ. of Tsukuba)
The 6 Li(d,p)7 Li reaction with polarized deuterons at an incident energyof 90keV; N. Yoshimaru (Univ. of Tsukuba)
Recent progress of studies on nuclear structure byusing fast RI beam; T. Motobayashi (RIKEN)High pT charged hadron analysis in 200 GeV Au+Au collisions
at RHIC-PHENIX; M. Shimomura (Univ. of Tsukuba)
Interaction of highly charged ion with matter;
Y. Takanashi (Univ. of Tsukuba)
Measurement of energy dependence of total reaction cross section of
12
C+p system around (p,n) threshold energy; H. Ishiguro (Univ. of Tsukuba)
Pursuing a Penta-quark State;
C. Rangacharyulu (Univ. of Saskatchewan, Canada)
FRS and Super-FRS - Present and Future of the GSI programwith radioactive nuclear beams; K. Suemmerer (GSI)- 91 -

8. SYMPOSIA
Unstable nuclei and nuclear synthesis with storage ring
12 March 2004
Tandem Accelerator Center, room C305, University of Tsukuba

1. Opening : A.Ozawa (Univ. of Tsukuba)
2. RIBF : Y.Yano (RIKEN)
3. Experiments at RIBF : T.Motobayashi (RIKEN)
4. BIG-RIPS and beam transport system : T.Kubo (RIKEN)
5. TARN II : T.Kikuchi (CNS)
6. Trigger system : A.Ozawa (Univ. of Tsukuba)
7. Measurements of mass and life time with TARN II : T.Otsubo (Niigata Univ.)
8. Internal target experiments with TARN II : T.Onishi (RIKEN)
9. Cluster structure in excited states of Be isotope : M.Ito (Univ. of Tsukuba)
10. Mass formula and r-process nuclear synthesis : H.Koura (RIKEN)
11. Storage ring and cluster physics : I.Arai (Univ. of Tsukuba)
12. Projects for RI beam physics in China : W.Q.Shen (SINR)
13. Search for proton halo for 27,28 P : H. Zhang (CIAE)
14. Production of unstable nucleus 8 Li at UTTAC : Y.Tagishi (Univ. of Tsukuba)
15. Measurements of magnetic moments for unstable nuclei at UTTAC : K.Matsuta (Osaka Univ.)
16. Study of nuclear synthesis at UTTAC : T.Hayakawa (JAERI)
17. β -ray angular distribution measurement on 20 F at UTTAC : T.Nagatomo (Osaka Univ.)
18. Closing : Y.Tagishi (Univ. of Tsukuba)

Electronic excitation and related phenomena in atomic collisions
22-23 March 2004
Tandem Accelerator Center, room C305, University of Tsukuba

1. Opening : H.Kudo (Univ. of Tsukuba)
2. Correlation between multiply ionized state measurement and resolving process of C60 Inducedby fast ion bombardment : A.Itoh (Kyoto Univ.)
3. Production of C60 and measurement of their decay process using a storage ring : S.Tomita(Univ. of Tsukuba)
4. Present status of cluster ion acceleration at TIARA : Y.Saito (JAERI, Takasaki)- 92 -

5. Energy transfer and electron emission induced by several atomic ions : T.Kaneko (Okayama
Univ. of Science)
6. Review on fast cluster ion acceleration and related phenomena : K.Sasa (Univ. of Tsukuba)
7. Secondary electron production induced by cluster collision : I.Arai (Univ. of Tsukuba)
8. In situ observation of materials during ion bombardments : H.Tsuchida (Nara Women’s Univ.)
9. 3-dimensional nano-fabrication of materials by fast heavy ion bombardments : K.Awazu (NIAIST)
10. Comment from the viewpoint of application of cluster : J.Matsuo (Kyoto Univ.)
11. Charge states of ions in tandem energy region : K.Shima (Univ. of Tsukuba)
12. Large angle and single scattering at solid surface : Y.Kido (Univ. of Ritsumei)
13. Cluster ion bombardment on high polymer material : K.Hirata (NIAIST)
14. Effective charge model in fast atomic cluster : H.Kudo (Univ. of Tsukuba)
15. Closing : K.Shima (Univ. of Tsukuba)- 93 -

9. LIST OF PERSONNEL
Accelerator Center
H. KudoK. Shima
T. Komatsubara
K. Sasa
S. Ishii
H. Kimura
H. Oshima
Y. Tajima
T. Takahashi
Y. Yamato
He Ming
M. Yamaguchi
K. Suzaki
M. OhkiDirector, Professor
Associate Professor
Assistant Professor
Assistant Professor
Mechanical Technician
Computer Technician
Electric Technician
Mechanical Technician
Electric Technician
Electric Technician
Research Fellow
Research Fellow
Technical Assistant
Administrative Stuff

Steering Committee
H. KudoR. Kanzaki
T. Komatsubara
Y. Miake
Y. Nagashima
M. Onoda
R. SekiK. Shima
Y. Tagishi
K. Takita
K. Yabana

Chairperson, Tandem Accelerator Center
Inst. of Biological Science
Tandem Accelerator Center
Inst. of Physics
Inst. of Basic Medical Science
Inst. of Physics
Inst. of ChemistryInst. of Applied Physics
Inst. of Physics
Inst. of Material Science
Inst. of Physics

Scientific Guests and Fellows
K. Awazu
National Lab. Advanced Industrial Science and Technology
M. Fujimaki
Waseda Univ.
Y. Nagasawa
Waseda Univ.
I. Daito
Nagoya Univ.
M. IioMiyazaki Univ.
T. Hayakawa
JAERI
T. Shizuma
JAERI
H. Sasaki
Tsukuba Nano-Tech.
H. Ishiyama
KEK
H. Miyatake
KEK
M. Tanaka
KEK
N. Yoshikawa
KEKY. Watanabe
KEK
T. Miura
KEK
K. Masumoto
KEK
K. Bessho
KEK
H. Matsumura
KEK
He Ming
China Institute of Atomic Energy
K. Furuno
Emeritus Professor
Q.B. Wang
KEK- 94 -

Research Members
Inst. of Physics
Y. AokiI. Arai
Y. MiakeN. Okumura
Y. Tagishi
M. Yamaguchi
Inst. of Applied Physics
E. Kita

H. KudoS. Esumi
M. Onoda

S. Katoh
A. Ozawa

T. Komatsubara
K. Sasa

K. Shima

A. Uedono

H. Yanagihara

K. Takita

H. Tanimoto

N. Ookubo

N. Umeda

Inst. of Material Science
T. Koyano

H. Mizubayashi

Inst. of Geoscience
R. Anma

M. Kurosawa

Inst. of Chemistry
R. SekiK. SuekiInst. of Basic Medical Science
Y. Nagashima
Graduate Students
Doctoral Degree Programs of Physics
J. Hasegawa

K. Satoh

Doctoral Degree Programs of Engineering
T. HaoB. HouDoctoral Degree Programs of Pure and Applied Science
S. Hamajima
T. Harigae
A. Hatanaka
Y. Ishibashi
M. Konno
H. Masui
M. Nagata
Y. Nagata
M. Nakazumi
S. SakaiJ. Sawahata
K. Shibata
T. Suzuki
S. Takagi
H. Tokano
Master’s Degree Programs of Science and Engineering
H. Arai
K. GotoT. Hinuma
S. Kaminaga
T. Kawagishi
M. Kubo
T. OokiT. Shimada
T. Shinba
Y. Takanashi
Y. Tsuruga
A. Ueki
Master’s Degree Programs of Environmental Science

S. Igarashi
K. Masuo
M. Narisawa
Y. Shimizu
N. Yagi

T. Ikeda
K. Miyakawa
M. OkaM. Shimomura

M. Iijima
S. Miyasaka
T. Shojo
H. Uematsu

H. Ishiguro
T. MutoT. Suzuki
N. Yoshimaru

K. Ikeuchi
K. Shibata
K. Yamagishi

T. Ishikawa
K. Takao

T. Matsuhiro
Under Graduates
Y. EndoK. MikiR. Uchiyama

K. Fujiwara
S. OonoK. Uehara

M. Furutani
Y. OonoH. Wakamatsu- 95 -