state （MeV） H He Li B C O F Al Si P S Cl Sc Cr Fe Ni Cu Br Ag I Ta Au
14 90

△

13 84

△ △ △ △

○ △ △ △ ○

△

12 78

△ △ △ ○ △ ○ ○ ○ ○ ○

○

11 72

△ △ △ ○2023○ ○ ○ ○ ○ ○ANNUAL REPORT

○

10 66

○ △ ○ ○ △ ○ ○ ○ ○ ○ ○ ○

○

9 60

○ ○ ○ ○ ○ △ ○ ○ ○ ○ ○ ○ ○ △ ○8 54○ ○ ○ ○ ○ ○ ○ △ ○ ○ ○ ○ ○ ○ ○ △ ○△UTTAC-93,△ 2024
△ △ ○

UTTAC

TANDEM ACCELERATOR COMPLEX

7 48○ ○ University○ ○ CRiES○of ○Tsukuba○ △ ○ ○ ○ ○ ○ ○ ○6 42○ ○ ○ ○ ○ ○ ○ ○○ ○ ○ ○ ○5 36

○ ○ ○ ○ ○ ○ ○ ○ ○○ ○ ○ ○ ○4 30

○ ○ ○ ○ ○ ○ ○ ○ ○○ ○ ○ ○

3 24

○ ○ ○ ○ https://www.tac.tsukuba.ac.jp/○ ○ ○ ○ ○ ○○ ○2 18 ○ ○ ○ ○ ○ ○ △1 12 ○ ○ ○

○ ○ ○

△

UTTACANNUAL REPORT 2023
April 1, 2023 − March 31, 2024

UTTAC-93, 2024

Editors : Tetsuaki Moriguchi, Kimikazu Sasa, Yoshihiro Yamato, Masumi Matsumura,
Masao Sataka, Hiroshi Naramoto, Eiji Kita, and Hiroshi Kudo (editor-in-chief)
UTTAC ANNUAL REPORT is a series of issues, which describes annual research
activities at Tandem Accelerator Complex, Research Facility Center for Science andTechnology, University of Tsukuba.
Copyright © 2023 by Tandem Accelerator Complex, Center for Research in Radiation,
Isotopes, and Earth System Sciences (CRiES), University of Tsukuba and individual
contributors.
All reports are written on authors’ responsibility and thus the editors are not liable forthe contents of the report.
Tandem Accelerator Complex, CRiES, University of Tsukuba
Tennodai 1-1-1, Tsukuba, Ibaraki 305-8577, Japanannual@tac.tsukuba.ac.jp

Cover: Table of typical ion beam intensities shown with corresponding marks, which is
updated annually as a guide for users of the 6MV tandem accelerator at UTTAC.
−−−from Report 1.3.

PREFACE
This annual report covers research and development (R&D) carried out at Universityof Tsukuba Tandem Accelerator Complex (UTTAC) during the fiscal year 2023 (1 April
2023 ~ 31 March 2024). The topics include not only accelerator-based R&D using the
6MV tandem and 1MV Tandetron accelerators, but also radioisotope-based R&D
employing positron annihilation spectroscopy and Mössbauer spectroscopy.
Additionally, UTTAC was reorganized as one of the divisions under the Center for
Research in Radiation, Isotopes, and Earth System Sciences (CRiES), effective on April
1, 2023.
September 1, 2024
Editorial Board

Editorial board

Evacuation drill in fall 2023 (in front of the entrance of UTTAC)-i-CONTENTS
1 ACCELERATOR OPERATION AND RELATED STUDIES

1

1.1

Accelerator operation 2023 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1

1.2

Production of a faint 58 Ni beam . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3

1.3

Search for the highest possible energy of the ions produced by the 6 MV tandem
accelerator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2 NUCLEAR AND COLLISION-BASED RESEARCH

5
7

2.1

Beam test of position-sensitive detectors for the RIKEN Rare-RI Ring facility . . .

7

2.2

The nuclear polarization of 29 P in semiconductor Si stoppers . . . . . . . . . . . .

9

2.3

Determining the composition of mixed molecular ion beams in the 1 MV Tandetron
accelerator using Rutherford backscattering . . . . . . . . . . . . . . . . . . . . . . 11

3 ACCELERATOR MASS SPECTROMETRY

13

3.1

Status report of the Tsukuba 6 MV multi-nuclide AMS system in FY 2023 . . . . 13

3.2

Riverine 129 I dynamics during high-ﬂow events in the Abukuma and Niida rivers . 15

3.3

Iodine-129 in seawater near the Fukushima Dai-ichi Nuclear Power

Plant before

and after the discharge of ALPS treated water . . . . . . . . . . . . . . . . . . . . 16
3.4

Distribution of I-129 in the land area after the Fukushima Daiichi Nuclear Power
Plant accident . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

3.5

The performance of iodine-129 AMS measurements at the University of Tsukuba(FY 2023) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

3.6

Challenges in measuring Pb-210 using accelerator mass spectrometry . . . . . . . . 21

3.7

Seawater circulation analysis in the Southern and Indian Oceans by cross-sectional
I-129 observation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

4 MATERIALS RESEARCH

23

4.1

Characterization of AlInN/AlN/GaN structures by means of positron annihilation

4.2

Hydrogen analysis of concrete samples by T-ERDA . . . . . . . . . . . . . . . . . . 25

4.3

Mössbauer study of antiferromagnetic FeMnMo alloy . . . . . . . . . . . . . . . . . 27

- ii -

23

4.4

Evaluation of reactively sputtered Fe oxide thin ﬁlm growth with Mössbauer spectroscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

4.5

Mössbauer study of an iron-based nanocrystalline alloy after annealing in magnetic
ﬁelds with various temperatures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

4.6

Mössbauer study of superparamagnetic iron oxide nanoparticles . . . . . . . . . . . 33

4.7

Operando NRA on all-solid-state Li ion battery using 6 Li isotope . . . . . . . . . . 35

4.8

Development of a rotational sample holder for ERDA on Fomblin oil surfaces . . . 37

5 ION-BEAM IRRADIATION EFFECT
5.1

39

Fabrication and functional development of one-dimensional organic nanostructuresusing high-energy charged particles . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

5.2

Morphology of the tracks of several-tens-MeV Au ions in YBa2 Cu3 O7−x studied
by cross-sectional transmission electron microscopy . . . . . . . . . . . . . . . . . . 41

5.3

Acquiring fundamental data for radiation protection of COTS-Grade FPGAs . . . 43

6 TECHNICAL REPORT
6.1

45

Accelerator maintenance 2023 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

7 LIST OF PUBLICATIONS AND PRESENTATIONS

47

7.1

Peer-reviewed and proceedings papers . . . . . . . . . . . . . . . . . . . . . . . . . 47

7.2

Reviews and books . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

7.3

Poster and oral presentations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

7.4

UTTAC seminars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

8 THESES

58

9 LIST OF PERSONNEL

59- iii -

1.
ACCELERATOR OPERATION AND RELATED STUDIESEngineers of UTTAC working for maintenance ofthe 6MV tandem accelerator.

1.1

Accelerator operation 2023

T. Moriguchi, S. Ishii, T. Takahashi, Y. Yamato, T. Yoshida, M. Matsumura, T. Nakazawa, K. Sasa
University of Tsukuba Tandem Accelerator Complex (UTTAC) is promoting the maintenance and operation of the tandem accelerator facility consisting of the 6MV Pelletron tandem accelerator and the 1MV
Tandetron accelerator for cooperative researches both inside and outside the University of Tsukuba. In October 2023, during the annual inspection of power supplies on campus, 400V AC was incorrectly applied to
the 200V AC power line of UTTAC. As a result, the inverter power supplies for the chain motors of the 6MV
tandem accelerator and the relay switches in the distribution board failed, hence all the scheduled beam time
was suspended for about two months. The damaged equipment was fully restored in late March 2024.
1MV Tandetron accelerator
The 1MV Tandetron accelerator has 2 negative ion sources and 4 beamlines. The operating time and theexperimental beam time of the 1 MV Tandetron accelerator were 908 and 250 hours, respectively, during
the total service time in ﬁscal 2023. The total number of operation days was 50, and the total of 26 research
programs was carried out. Figures 1 and 2 show classiﬁcation of the accelerated ions and of the experimental
purposes, respectively. At the end of March 2024, the number of approved research programs was 3 for oncampus and 7 for off-campus. The terminal voltage instability reported last year [1] was also observed
frequently in FY2023, and the investigation of this issue is now underway.

CH
3%

CH2 OH OH2
3% 2% 2%
Education
6%

RBS/ERDA
14%

H
27%

C2
22%

Beam test
4%

NRA
14%

C
24%

He
14%

H2
3%

Cluster physics
62%

Fig. 1. Accelerated ions from the 1MV Tandetron accelerator in FY2023.

Fig. 2. Purposes of use of the 1MV Tandetron
accelerator in FY2023.

6MV Pelletron tandem accelerator
The 6MV Pelletron tandem accelerator has 5 negative ion sources and 12 beamlines. The operation
time and the experimental beam time of the 6MV Pelletron tandem accelerator were 1,022 and 832 hours,
respectively, during the total service time in ﬁscal 2023. The total number of operation days was 96, andthe total of 57 research programs was carried out. Figure 3 shows the beam time histogram with respect
to the terminal voltage. Figures 4 and 5 show classiﬁcation of the accelerated ions and of the experimental

1

purposes, respectively. At the end of March 2024, the number of approved research programs was 8 for
on-campus and 5 for off-campus.

Terminal voltage (MV)

6
5
4
3
2
1
0

100

200
300
Beam time (hours)

400

500

Fig. 3. Beam time histogram as a function of the terminal voltage for the 6MV Pelletron tandem accelerator
in FY2023.

Beam
Irradiation
Effect7%
IBA
4%
Beam test
1%

Pb
2.5%
Au
6.6%
H
22.3%
D
1.3%

I
53.4%

Li
He
4.4% 0.4%CCl
0.4%
6.4% PSi
0.3% 0.4%

Developments
3%
Education
2%

Nuclearphysics
20%

AMS
63%

Ni
1.8%

Fig. 4. Accelerated ions from the 6MV Pelletron tandem accelerator in FY2023.

Fig. 5. Purposes of use of the 6MV Pelletron
tandem accelerator in FY2023.

Reference[1] K. Sasa et al., UTTAC Annual Report 2022, UTTAC-92 (2023) 1.

2

Production of a faint 58 Ni beam

1.2

T. Moriguchi, K. Sasa, Y. Yamato, T. Yoshida, S. Ishii, T. Takahashi, M. Matsumura, T. Nakazawa
For research and development of particle detectors, a faint beam is necessary to evaluate their performances without deterioration. In the last FY, we developed a faint beam of 12 MeV H+ which was transported to the A7 course in the experimental room [1]. In FY2023, we transported a faint 58 Ni beam to theA7 course, as reported below.
A 58 Ni beam from the 6MV tandem accelerator cannot be extracted to the air for measurement of thecount rate, unlike 12 MeV protons, since the Ni beam stops in a thin vaccum-seal window. Therefore, we
installed a plastic scintillation counter (PL) at the scattering chamber in the A7 course. The disc-shaped
plastic scintillator (Saint-Gobain BC400, ϕ 1 in., 3 mm thick) was mounted with a photomultiplier tube
(HAMAMATSU PHOTONICS K.K., R9880U-210) using a transparent gel (Shin-Etsu Chemical Co., Ltd.,
KE-1051J-A/B). The diameter of the plastic scintillator is almost the same as that of the effective area of astandard Faraday cup in the beam line. As shown in Fig. 1 (a), the PL was attached with the target ladder inthe scattering chamber along with an alumina ﬂuorescent plate (Desmarquest Co., AF995R) and a ZnS:Ag
phosphor applied to a clear polyester plastic sheet (ELJEN TECHNOLOGY, EJ440).

(a)

(b)
Alumina
Plastic
scintillation
counter

ZnS:AgAlumina
ZnS:Ag

2 mm/div

Fig. 1. (a) A plastic scintillation counter, an alumina plate, and a ZnS:Ag sheet which are attached with thetarget ladder in the A7 course. (b) The beam spot on a ZnS:Ag sheet.

To produce a faint beam, a beam of 84 MeV 58 Ni13+ with a full intensity of ∼0.2 nA, which wasmeasured by the A7 Faraday cup, was ﬁrstly transported to the A7 course. While maintaining the fullintensity, the beam spot was adjusted by using the ZnS:Ag sheet because the alumina plate was much lessluminous (Fig. 1 (b)). Afterwards, we inserted an attenuator upstream of the accelerator, and closed thelow-energy beam slits (LE-slit) to the lower limit, indicating the 1.0-mm squared aperture. At this time,
the beam count rates of ∼100 cps were measured by the PL at the A7 course. For attenuation of the 58 Ni

3intensity, defocussing of the beam without activating the quadrupole magnet was not needed unlike faintprotons because the full intensity of 58 Ni13+ was low. By varying the aperture of the LE-slit, the count rate
was able to be optimized as requested. The faint 58 Ni+13 beam was provided for the performance test of
position-sensitive detectors [2]. It is notable that in the similar trial the beam intensity of 58 Ni14+ was too
low to be transported [3].
The present development was conducted as part of a course of Target Oriented Group Study offered by
the College of Physics, and we thank K. Matsuda, who was a student of this course, for the preparation of
the PL.

References[1] T. Moriguchi et al., UTTAC Annual Report 2022, UTTAC-92 (2023) 5.
[2] T. Yamaguchi et al., this Annual Report 2.1.
[3] M. Sataka et al., UTTAC Annual Report 2022, UTTAC-92 (2023) 3.

4

1.3

Search for the highest possible energy of the ions produced by the 6 MV
tandem accelerator

M. Sataka, T. Takahashi, H. Naramoto, H. Kudo, K. Sasa
Acceleration tests of ion beams obtained from the 6MV tandem accelerator at UTTAC have been
continued [1]. High-energy heavy ion beams are required for ion irradiation experiment for materials sciencesuch as ion beam modification of materials [2,3]. High-energy ion beams of very weak intensities areindispensable for radiation resistance tests of semiconductors used in space [4].
We have measured beam currents of the accelerated ions as a function of the ion charge at the acceleration
voltage from 3 to 6 MV. In this fiscal year, data of P ions were newly obtained, while the previous Si data
were updated. Figure 1 shows the beam current distributions of P ions as a function of the ion charge at the
maximum terminal voltage of 6 MV. A carbon stripper foil of approximately 5 µg/cm2 thickness was usedat the 6 MV terminal.
In this accelerator control system, the minimum measurable current of the Faraday cup is 0.1 nA. However,
it is required to measure lower currents to search for the maximum ion energy. In the test measurement, thebending magnets, lenses and steerers were preset to the estimated values, thereby leading the ion beam tothe end Faraday cup with a picoammeter at the experimental apparatus. The beam operation time was not
significantly different from that for high current ions. For lower current ion beams, a particle detector wasused instead of a picoammeter.

100

Ion Current (nA)

10
1
0.1
0.01
0.001

5

6

7

8

9

10

11

12

13

14

15

Charge State
Fig. 1. Ion beam current distribution for P ions at the terminal voltage of 6 MV. A foil
stripper was used in the high voltage terminal.

5

Table 1 shows the ion charges and maximum energies obtained by injection of negative atomic ions at
the highest terminal voltage of 6 MV. These data were accumulated from 2016 to 2023.
Table 1. Summary of the acceleration tests from 2016 to 2023 for injection of negative atomic ionsat the highest terminal voltage of 6 MV. The measured beam intensities are shown by the symbols:○: ≥ 1nA, △: ≤1nA. Shown in red are those obtained by using foil strippers.

charge energy

state （MeV） H

He

Li

B

C

O

F

Al

Si

P

S

Cl

14

90

13

84

△

△

12

78

△

11

72

10

66

9

60

8

54

○

7

48

6

42

5

36

○

4

30

3

24

2

18

○

1

12 ○

○

○

Sc

△

Cr

Fe

Ni

Br

Ag

I

△

△

○

△

△

△

△

○

△

○

○

○

○

○

○
○

△

△

△

△

○

△

△

○

△

Cu

Ta

Au

△

△

△

○

○

○

○

○

○

○

○

△

○

○

△

○

○

○

○

○

○

○

○

○

○

○

○

△

○

○

○

○

○

○

○

△

○

○

○

○

○

○

○

△

○

○

○

○

○

○

○

△

○

○

○

○

○

○

○

○

△

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

○

△

○

○

○

○

Some ion beams are formed from negative molecular ions (e.g., nitrogen and Ca ion beams), rather thanfrom negative atomic ions. In these cases, the energies of the accelerated ions are not given in Table 1, as
those cannot be determined solely from the terminal voltage and the ion charge after acceleration. The dataof molecular ions (N, Al, Ca, Sc, Ti, Mo, W) accumulated from 2016 to 2022 were presented in the previous
report [1].
References[1] M. Sataka et al., UTTAC Annual Report 2022, UTTAC-92 (2023) 3 and references therein.
[2] M. Nobuoka et al., in this annual report 5.1.
[3] H. Matsui et al., in this annual report 5.2.
[4] H. Kukita et al., in this annual report 5.3.

6

2.
NUCLEAR AND COLLISION-BASED RESEARCH

Development of a high-sensitivity X-ray detector.

2.1

Beam test of position-sensitive detectors for the RIKEN Rare-RI
Ring facility

T. Yamaguchi1,2 , K. Sasaki2 , K. Takiura2 , Y. Kikuchi2 , S. Nishizawa2 , N. Tomioka2 , K. Watanabe2 , T.
Suzuki2 , T. Moriguchi, A. Ozawa, A. Yano
We have been developing the storage ring facility called Rare-RI Ring (R3) [1] at the RI Beam Factory in
RIKEN for precision mass spectrometry of exotic nuclei. Rare-RI Ring is coupled with the RIBF cyclotron
facility and hence individually stores a single ion of interest at a time, which is in-ﬂight selected at the
fragment separator BigRIPS. To realize such a new injection scheme, a long injection beam line is equipped,
where many beam diagnostics detectors need to be installed. They should be easily operated, maintained
and are required to equip with a low cost. More important is to conﬁrm the ion-optical condition, emittanceand dispersion matching at the injection kicker position. Therefore, a compact design that ﬁts into the gap
in the kicker chamber is required. For this purpose, we have developed several shaped plastic scintillation
detectors for position detection, and tested with swift heavy ions at the Heavy Ion Medical Accelerator in
Chiba (HIMAC) facility [2] and with a 12-MeV proton beam at the 6-MV tandem accelerator in Universityof Tsukuba.
In the previous annual report in 2021 [3], we reported an one-dimentional position-sensitive detector.
The detector consists of a simple plastic scintillator plate (100 × 100 mm2 , 3 mm thick) and three bundled
wavelength shifters, WLS (each 1 × 1 mm2 , Kuraray Y-11), which is an easy and cost effective solution. The
WLS are connected at the up and down side of the scintillator plate, and the photons from WLS are read out
by four photo sensors at four corners: left-up (LU), left-down (LD), right-up (RU), and right-down (RD).
A photo of the detector is shown in Fig. 1 of ref. [3]. For a 200-MeV/u Kr beam at the HIMAC facility,
a position resolution of 1.2 mm (σ ) in the y-direction was obtained from the pulse height ratio which isdeﬁned as Ey = (QLU − QLD + QRU − QRD )/(QLU + QLD + QRU + QRD ). Here, Qi means an integrated
charge measured with a charge-sensitive analog-to-digital converter, and the subscript i means each positionof the photo sensors as described above. A linear relation in a wide range has been achieved.
Through several experiments done so far, it turns out that the position resolution is inversely proportional
to the square root of the energy deposit, as shown in Fig. 1(a). To conﬁrm this character, we employed a
Ni13+ beam with an energy of 84 MeV this time [4]. All the detector setups were installed in a vacuum
chamber connected at the end of the A7 beam course. Although the expected energy deposit (∆E −1/2 ≈0.11 MeV−1/2 ) should be around the middle of the ﬁtting line in Fig. 1(a), the observed pulse heights were
unexpectedly small due to a short range in plastic, ≈20 µ m, and thus possible photon transport deteriorated.
However, the result of position resolution, ≈15 mm, consistently matches the straight line, meaning anenergy deposit of 4-5 MeV equivalent to the ofﬂine test with a standard α -source 241 Am.
To further upgrade this detector, the present position-sensitive plastic scintillation detector is coupledwith a scintillating ﬁber detector [4]. On the one hand, the present detector has a limited position resolution
depending on the energy deposit of beam, whereas it is compact and simple readout. On the other hand, thescintillating ﬁber detector has an excellent resolution, while ﬁber readout is generally complicated. Thus, to
1 Visiting associate professor appointment
2 Department of Physics, Saitama University

7

Fig. 1. (a) Position resolution as a function of the inverse square root of energy deposit into the present
detector. (b) Proton beam distribution measured by the prototype scintillating-ﬁber detector.

combine both features is beneﬁcial.
A prototype scintillating ﬁber detector, which consists of 64 scintillating ﬁbers with a square cross section of 1 × 1 mm2 , was built and successfully tested by using a 12-MeV proton beam. The light output
is read out from both ends of the ﬁbers with Multi-Pixel Photon Counters (Hamamatsu S13360-6075CS).
To reduce the number of readout channels, in one end, successive 8 ﬁbers out of 64 ﬁbers are connected
together into a MPPC, and at the other end every 8 ﬁbers out of 64 ﬁbers are connected in the same manner.
In total 16 MPPC are used. By combining the hit patterns of MPPC at both ends, one can reconstruct the hit
position out of the 64 ﬁbers, that is the beam position distribution. The present readout method is based ona previous work [5]. A typical result of 12-MeV proton beam distribution is shown in Fig. 1(b).
We have recently built new detectors with 100 ﬁbers of 1-mm diameter and with 300 ﬁbers of 0.5-mm
diameter, and are ready for beam test. The developments are ongoing.
References[1] A. Ozawa et al., Prog. Theo. Exp. Phys. 2012 (2012) 03C009.
[2] M. Kanazawa et al., Nucl. Phys. A 746 (2004) 393c.
[3] T. Yamaguchi et al., UTTAC Annual Report 2021, UTTAC-91, 12 (2022).
[4] T. Moriguchi et al., this Annual Report 1.2.
[5] T. Yamaguchi et al., Nucl. Instrum. Methods Phys. Res. B 317 (2013) 697.

8

2.2

The nuclear polarization of 29 P in semiconductor Si stoppers

A. Yano, A. Ozawa, T. Moriguchi, Y. Yamato, K. Tomita, N. Kaname, M. Hayashi, A. Moriyama, H. Zhang,
T. Matsumoto
It is known that nuclear polarization depends on beam energies and stopper materials. Thus, as a priorstep of the study of 30 P nuclear polarization, we investigated the nuclear polarization of 29 P with various
types of semiconductor Si stoppers and various beam energies. This approach is reasonable because all P
isotopes should have the same magnetic dipole interactions in stoppers.
We irradiated the Si targets with polarized proton and deuteron beams. Then, polarized 29 P was generated
via polarization transfer reaction. Because we used thick targets, production targets and stopper materials
are the same in our experiments. Experimental setup is similar to the previous experiment [1].
Typical β –NMR spectrum is shown in Fig. 1. The horizontal axis represents the applied RF frequency,
g where A is the asymmetry parameter of 29 P and P is the polarization
while the vertical axis represents 4AP,
g is not corrected for solid angles in detectors and effects of contaminants. Here, weof 29 P. Note that 4AP
g for RF off and at 2.65 MHz which corresponds todeﬁne the β –NMR effect as the difference between 4AP
the resonance in Fig. 1. Fig. 2 shows beam energy dependence of the nuclear polarization of 29 P. Verticalaxis indicates calculated polarization, P̃, from the β –NMR effects. Polarized deuteron beams induce ∼6%polarization, and it is almost constant. In contrast, polarized proton beams induce less than 2% polarization,and the lower the beam energy, the smaller the polarization.

Fig. 2. Beam energy dependence of the nuclear
polarization of 29 P.

Fig. 1. Typical β –NMR spectrum. Experimental conditions are written in bottom left.

Regarding the stopper material dependence, obvious differences were observed in the previous experiment [2] for four types of Si stoppers with polarized proton beams. In this study, we conducted similar
measurements with polarized deuteron beams. As a result, we obtained a more signiﬁcant dependence withpolarized deuteron beams compared to polarized proton beams, as shown in Fig. 3. The label high (low) indicates the high (low) –impedance. To clarify this dependence, we conducted spin relaxation measurements
as well. We show the experimental data and the ﬁtted curves in Fig. 4. UD ratio on the vertical axis indicatesthe ratio of the number of spin–up 29 P to the number of spin–down 29 P. Figure 4(a) shows the Si (n-type,low) data, while Fig. 4(b) shows the Si (p-type, low) data. To determine spin relaxation times, we ﬁtted theexperimental data with equations below. Equation 1 is for Fig. 4(a), and Eq. 2 is for Fig. 4(b) where a1, b1,

9a2, b2, c1, a, b, and c are ﬁtting parameters.
 x
 x
f it1(x) = a1 · exp −+ a2 · exp −
+ c1
b1
b2

(1)

 x
f it(x) = a · exp − + cb(2)

Figures 4(a) and 4(b) have a common component with a spin relaxation time of ∼9 s corresponding to
b1 and b. Additionally, Fig. 4(a) has a component with the opposite spin direction and a long spin relaxation
time of ∼18 s corresponding to b2. The cause of this opposite component could be the contaminants
polarization or the trapping of 29 P in at least two sites of Si (n-type, low) unlike Si (p-type, low). To
understand the reason of this long relaxation time, we will measure the resonance of 29 P precisely and will
determine its width.

Fig. 3. Target dependence of the β –NMR effects. The solid triangles correspond to 8 MeV, and the open
triangle corresponds to 10 MeV. For comparison, the data of polarized proton beam with beam energy of
12 MeV are plotted with circles.

Fig. 4. (a) Spectrum of the spin relaxation with Si (n-type, low), and (b) with Si (p-type, low).

References[1] A. Ozawa et al., UTTAC Annual Report 2017, UTTAC-87 (2018) 7.
[2] A. Ozawa et al., UTTAC Annual Report 2019, UTTAC-89 (2020) 7.

10

2.3

Determining the composition of mixed molecular ion beams in the 1 MV
Tandetron accelerator using Rutherford backscattering

Y. Yano, U. Ozeki, K. Minami, T. Nakazawa, S. Ishii, K. Sasa, S. Tomita
The acceleration of molecular ions using tandem accelerators is of great interest in many research fields.
However, the accelerated molecular ion beam can often be a mixture of intact molecular ions with the samemass-to-charge ratio. The ability to determine the composition of these mixed molecular ion beams is not
only crucial but also has significant practical implications, as it allows us to optimize the beam for specificapplications.
This study presents a novel application of the Rutherford backscattering method to quantify individualcomponents in mixed molecular ion beams accelerated by the 1 MV Tandetron accelerator at UTTAC. From
the analysis of the Rutherford backscattering spectra of the accelerated ions, the proportions of the molecularand atomic components could be determined, providing the composition of the mixed beam.
The experiments were conducted at the 1 MV Tandetron accelerator at UTTAC. We selected a mixed ion
beam with m/q = 13, comprising the molecular ion 12CH+ and the atomic ion 13C+, as a representative
example. These ions were initially generated by sputtering graphite with Cs ions. To estimate the preacceleration proportions of 12CH+ and 13C+, we measured the beam currents of m/q = 12 and 13 using a
Faraday cup located upstream of the accelerator. Assuming the natural abundance for the intensity ratio of
12

C+ and 13C+, we estimated the current of 13C+ in the beam m/q = 13 to be 11%.
Rutherford backscattering was employed to determine the composition of the accelerated mixed

molecular ion beam. The beam of m/q = 13 ions was accelerated to 120 keV/u, and incident on a thin 57.8
nm Au film target evaporated on highly oriented pyrolytic graphite (HOPG). The energy spectra of thebackscattered ions were measured using a Passivated Implanted Planar Silicon detector (PIPS) placed at
150° relative to the incident beam.
Rutherford backscattering spectra of the accelerated m/q = 13 ion beam showed the superposition of the
12

C+ and 13C+ spectra, originating from the molecular ion 12CH+ and the atomic ion 13C+, respectively (Fig. 1).

Simulations of the Rutherford backscattering of 12C+, 13C+, and H+ with the same velocity 120 keV/u were
performed using the simulation code SIMNRA [1]. The intensity of the spectra was determined by fitting
the measured spectra with the simulated spectra of 12C+ and 13C+ using the least-squares method. The postacceleration proportions of 12CH+ and 13C+ in the mixed beam were determined to be 62.4% for 12CH+ and37.6% for 13C+ for the present case. The validity of the obtained proportions can be confirmed by comparing
the calculated H+ spectrum from the obtained intensity of 12CH+ ion with the measured H+ spectrum (Fig.
1).
The 13C+ ratio obtained is higher than the estimated ratio of pre-accelerated ions. This is due to the chargeexchange process at the high-voltage terminal. At the terminal, the pre-accelerated negative ions collide withthe charge stripper gas, producing positively charged ions through an electron loss process. The molecularion could dissociate at this stage due to the collision process. In this sense, the fraction of molecular ionsdepends on the partial pressure of the charge stripper gas. As complementation, we measured the fraction of

11

13

C+ in the accelerated m/q = 13 ion beam as a function of the partial pressure of the change stripper gas.

The partial pressure was monitored by the vacuum pressure of the accelerator at the terminal. The results
show that the 13C+ fraction in the beam m/q = 13 increases with the partial pressure of the charge strippergas (Fig. 2) and reaches almost 100% for the high partial pressure of the stripper gas.
The results demonstrate that Rutherford backscattering can effectively quantify individual components inmixed molecular ion beams. This information is vital for characterizing the composition of the accelerated
mixed beam and understanding the molecular ion acceleration process.

Fig. 1. Rutherford backscattering spectra of the accelerated m/q = 13 ion beam, alongside simulated spectra of
12

CH+ and 13C+, utilized for determining post-acceleration proportions. Also shown is the sum of the simulated

spectra 12CH+ and 13C+.

Fig. 2. The relationship between the vacuum pressure at the terminal of the accelerator, which monitors the partialpressure of the charge stripper gas, and the proportions of 12CH+ and 13C+.

Reference[1] M. Mayer, SIMNRA User's Guide, Max-Planck-Institut für Plasmaphysik, Garching, Germany, 1997.

12

3.
ACCELERATOR MASS SPECTROMETRY

New Ta-covered wheel for Cl-36 AMS

3.1

Status report of the Tsukuba 6 MV multi-nuclide AMS system in FY 2023

K. Sasa, T. Takahashi, M. Matsumura, T. Yoshida, A. Sakaguchi, T. Matsunaka 1
The Tsukuba 6 MV multi-nuclide AMS system was operated for a total of 43 days and 516.6 hours in FY
2023. Figure 1 shows monthly-measured rare nuclides from April 2023 to March 2024. During the year, 595
samples were measured, mostly for 36Cl and 129I, and test measurements of 210Pb were performed in thedevelopment of AMS. Table 1 shows the breakdown of the measured samples.
140

Number of Pieces

120

Cl-36

I-129

Pb-210

100
80
60
40
20
0

Apr-23 May-23 Jun-23

Jul-23 Aug-23 Sep-23 Oct-23 Nov-23 Dec-23 Jan-24 Feb-24 Mar-24

Monthly measured nuclides

Fig. 1. Monthly-measured nuclides from April 2023 to March 2024.
Table 1. Number of measured samples in FY 2023.

Item
Cl-36
I-129
Pb-210Sub total

Reagent & Blank Standard samples
8
4
63
42
55
6
126
52

Analyzed samples
7
407
3
417

Total
19
512
64
595

Cl-AMS36

Cl− extracted from AgCl was positively charged after passing through a carbon foil (3.6 µg/cm2) at theacceleration voltage of 6.0 MV, and 36Cl7+ was detected at 48 MeV in 36Cl-AMS. There is a problem withisobar 36S contaminations from the Cu wheel disk containing sample cathodes when Cl− is extracted fromthe Cs sputtering ion source. We attempted to suppress isobar 36S contaminations by covering the surface of
the Cu wheel disk with a 0.50 mm thick Ta plate. As a result, the contribution of 36S was reduced by abouta factor of 50, as shown in Figure 2. In FY 2023, we have conducted joint research with Guangxi Normal
University in China to measure anthropogenic 36Cl in soil, and also with KEK to measure 36Cl in activatedchloride sheathing covering cables in the large accelerator room.
I-AMS

129

129

I-AMS has been performed under the beam condition of 129I5+ with 30.0 MeV using an Ar gas stripper

at the terminal voltage of 5 MV. In FY 2023, 129I-AMS was mainly applied to 129I tracer studies for ocean
circulation studies, the discharge of ALPS-treated water to the sea at Fukushima and Iodine-129 deposition
from atmosphere in the sample preparation rooms.

1Kanazawa University

1336Cl7+: 48 MeV

76.8 cps/35Cl (1 µA)

36S

22106
counts

1.6 cps/35Cl (1 µA)

New
dE4+dE5 (ch)dE4+dE5 (ch)

Old

36Cl

36S

2898
counts936
counts36Cl

6792
countsCu wheel+Ta（0.5mm）

Cu wheel

dE1+dE2 (ch)dE1+dE2 (ch)20221020Cl36MT_run38_05
le35Cl : ∼2.4 µA
Measurement time : ∼2min.

20240313Cl36MT_run234_04
le35Cl : ∼7.5 µA
Measurement time : ∼4min.

Fig. 2. Comparison of the ratios of 36S to 35Cl counts between the Cu wheel (old) and the Ta-covered Cu
wheel (New), showing the drastic reduction of 36S contamination. Measured sample: KNCl-STD (36Cl/Cl= 5.000 × 10−12).

Pb-AMS210

AMS development is underway for 210Pb (a half-life of 22.2 years) in FY2023. PbO2− was successfully
extracted as Pb negative molecular ions up to 550 nA from Pb3O4. Pb5+ was accelerated at the acceleration
voltage of 3 MV, and a test detection was performed for a mass number of 210 using the gas ionizationchamber. Detail of the 210Pb AMS development is presented in Ref. [1].
Measurement history
1200

Number of AMS measuring samples

1000
800

200
0

C-14

Al-26

Cl-36

Ca-41

Sr-90

I-129

Pb-210

484

88

600
400

Be-10

294

143
184
30
321

13

FY 2016

29

119
29
322

FY 2017196
180
FY 2018

23
13

257

50

165
187

29

85
FY 2019

FY 2020

507

427

377

42
FY 2021

512
72

FY 202219
FY 2023

Fiscal year

Fig. 3. Cumulative number of measured samples for AMS since 2016.

Figure 3 shows the cumulative number of measured samples since the AMS system started operation. A
total of 5,147 samples was measured from FY 2016 to 2023. AMS of the radioactive halogens 36Cl and 129I
has been performed mainly at the Tsukuba 6 MV multi-nuclide AMS system since FY2020 [2].
References[1] H. Takahashi et al., this Annual Report 3.6.
[2] K. Sasa et al., Annual Report 2022, UTTAC-92 (2023) 16.

14

3.2

Riverine 129I dynamics during high-flow events in the Abukuma andNiida rivers

Y. Wakiyama 1, M. Matsumura, T. Matsunaka 2, S. Hirao1, K. Sasa
The long-lived 129I (half-life: 15.7 million years) is one of radionuclides of interest released by the
Fukushima Daiichi Nuclear Power Plant (FDNPP). Post-accidental research has revealed impact of 129I
release/deposition on various environmental media, such as rainwater, soil, and seawater. However, there
have been few investigations on 129I redistribution on terrestrial environment. To tackle this issue, we haveanalyzed river water samples collected from rivers under high-flow conditions since 2019 in the flameworkof Environmental Radioactivity Research Network Center (ERAN).
The first set of samples were collected at the Kuroiwa site (catchment area 2890 km2 and catchment mean
137

Cs inventory 103 kBq/m2) on midstream of the Abukuma river in July and October 2018, the second at

the Haramachi site (206 km2 and 853 kBq/m2) on downstream of the Niida river in August 2016 and October
2017, and at the Warabidaira site (29 km2 and 1420 kBq/m2) on Hiso river, an upstream tributary of theNiida river, in August 2016. All river water samples were filtered with a 0.45 µm membrane filter, and thus
obtained samples of suspended solids (SS) and filtrates were subject to pretreatment, 129I/127I ratio
measurement by accelerator mass spectrometry, and 127I concentration measurement by ICP-QQQ-MS [1].
Table 1 summarizes results of 129I analyses. 129I concentrations and 129I/127I ratios at the Kuroiwa site werein range of the background level before the FDNPP accident. Mean values of 129I concentrations and 129I/127I
ratios were the highest at the Warabidaira site, followed by the Haramachi site, and then the Kuroiwa site.
This magnitude-relation coincided with that of catchment mean 137Cs inventory, as an index of 129I
deposition level in the catchments. Apparent distribution coefficients also appeared to depend on thecatchment mean 137Cs inventory. These results suggest that Fukushima-derived 129I may have a strong
affinity to soil/sediment particles.
Table 1. Summary of results of 129I analyses. n indicates the number of analyzed samples.
Site(river name)

Sample collection
periodn

Kuroiwa(Abukuma)
Haramachi(Niida)Warabidaira(Hiso)

5-7 Jul. 2018
1-3 Oct. 2018
16-17 Aug. 201622-23 Oct. 2017

5
7
5*
6

Mean
dissolved
129
I conc.
(μBq/L)
0.179
0.06770.174
0.129

16-17 Aug. 2016

5

0.236

Mean 129I
conc.
in SS
(mBq/kg)
1.03
0.437
4.07
2.36

Mean
distribution
coefficient(L/kg)
4330
6060
22500
22200

Mean
129 127
I/ I
in water(10-9)
2.28
2.25
5.53
4.92

Mean
129 127
I/ I
in SS(10-9)
2.25
4.81
27.6
31.3

11.2

56100

10.4

48.5

* n for Mean 129I conc. in SS, Mean distribution coefficient, and Mean 129I/127I in SS were four.
Reference[1] Y. Muramatsu et al., J. Environ. Radioact. 139 (2015) 344.
1Fukushima University
2Kanazawa University

15

3.3

Iodine-129 in seawater near the Fukushima Dai-ichi Nuclear Power
Plant before and after the discharge of ALPS treated water

H. Miura 1, T. Matsunaka 2, K. Sasa, T. Takahashi, M. Matsumura
Anthropogenic 129I is released into the ocean mainly from nuclear weapon tests, nuclear reprocessing
facilities, and nuclear accidents including the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident.
Since August 2023, Tokyo Electric Power Company (TEPCO) has been releasing advanced liquid
processing system (ALPS)-treated water, which contains trace amounts of 129I, into the Pacific Ocean. This
study aims to obtain the distribution of 129I in seawater using AMS, which will help us in predicting
concentration of 129I by the model-based calculation for the radiation dose assessment. In this year, seawatercollected before the discharge of the ALPS-treated water was analyzed.
Surface seawater was collected in the coast of Fukushima Prefecture by the research vessel Shinsei Maru
(October 2022), and near the FDNPP by a fishing vessel (April and July 2023). Extraction and purificationof I were carried out at Low Level Radioactivity Laboratory (LLRL), Kanazawa University. The 129I/127I
ratio was measured using the AMS at University of Tsukuba. A terminal voltage of 5 MV and a charge stateof 5+ were chosen. The measured ratios were normalized against the Purdue-1 reference material (129I/127I= 8.37 × 10-12) obtained from Purdue University. I-127 alkaline solution was measured by ICP-MS. The
I/ I ratio and 129I in the seawater were calculated using 129I/127I ratio from AMS and 127I concentration

129 127

from ICP-MS.
Figure 1 shows the distribution of 129I (Bq/L) in the coast of Fukushima Prefecture. The 129I concentration
has remained at the pre-accident level (10-8 Bq/L) at points excluding the NP0 near the nuclear power plant.
On the other hand, the 129I concentration at NP0 was about two orders of magnitude higher than those at theother points. Figure 2 shows the sampling sites and 129I concentrations near the nuclear power plant. The 129I
concentration near the nuclear power plant was about one order of magnitude higher on average, with alarge variability of about two orders of magnitude, suggesting continuous leakage of contaminated waterfrom the FDNPP. The next purpose of this study is analyzing seawater collected after the discharge of ALPStreated water to evaluate the impact of the water discharge.

1Central Research Institute of Electric Power Industry
2Kanazawa University

16

(°)

(°)
Fig. 1. 129I concentration in the coast of Fukushima Prefecture.

Fig. 2. Sampling sites within 5 km from the FDNPP (Left). 129I concentrations in seawater near the
FDNPP (Right).

17

3.4

Distribution of I-129 in the land area after the Fukushima Daiichi
Nuclear Power Plant accident

M. Matsumura, K. Sasa, T. Matsunaka 1, R. Tomita2, T. Takahashi, H. Matsuzaki3, K. Sueki
A significant amount of radioactive material was released into the environment after the accident after
the accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP) on March 11, 2011, with atmosphericemissions commencing on March 12 and peaking during March 15–16 and 20–22 (TEPCO, 2012).
Anthropogenic sources such as nuclear-fuel reprocessing plants had already increased the 129I level in theenvironment above its natural background (129I / 127I = 1.5 × 10–12; e.g., [1]). Total amounts of radionuclides
discharged into the atmosphere by the FDNPP accident was estimated to be 8.1 GBq of 129I (T1/2= 1.57 ×
107 y) [2] and 120 – 200 PBq of 131I (T1/2= 8.02 d) [3]. The long-lived 129I can be used as a tracer toretrospectively infer the level of 131I. We got a result that the average of 129I concentration was (2.74 ± 1.35)
× 108 atoms/g prior to the FDNPP accident as 129I background data at Fukushima. After the FDNPP accident,
the weighted average of 131 I / 129I ratios was estimated to be (4.02 ± 0.81) × 10−2 in 5-cm-thick surface soilsof Fukushima area corrected to the time of earthquake [4].
Thirteen years have passed since the accident, but 129I released into the environment still exist throughrepeated deposition and resuspension. We investigated the concentration of 129I and isotopic ratio of 129I /127

I in river water in Fukushima Prefecture, at five points on the Niida River, once per year, from 2014 to2020. The samples were analyzed using AMS at MALT, The University of Tokyo, until 2015 [5], and at
UTTAC since 2016 [6]. The analysis results areshown in Fig. 1. The 129I concentrations are in therange (0.35−2.8) × 108 atoms L-1, and the 129I / 127I
ratio is (0.51−4.6) × 10−8. It appears that, as time
passes, the 129I concentration decreases quickly at
first, then slowly converges to a constant value.
This work was supported in part by the
KAKENHI under grant Nos. of 15H02340,
19H04252 and 22H02001
References[1] J. E. Moran, et al., Environ. Sci. Technol. 33 (1999) 2536.
[2] X. L. Hou, et al., Environ. Sci. Technol. 47 (2013) 3091.
[3] M. Chino et al., J. Nucl. Sci. Technol. 48 (2011) 1129.
[4] K. Sasa, et al., UTTAC Annual Report 2013, UTTAC-83 (2014) 37.
[5] H. Matsuzaki et al., Nucl. Instrum. Meth. Phys. Res. B 361 (2015) 63.
[6] K. Sasa et al., Nucl. Instrum. Meth. Phys. Res. B 437 (2018) 98.
1Kanazawa University

2Japan Atomic Energy Agency
3The University of Tokyo

18

3.5

The performance of iodine-129 AMS measurements at the University ofTsukuba (FY 2023)

M. Matsumura, K. Sasa, T. Takahashi, T. Yoshida, T. Matsunaka 1
We have reported the performance of 129I measurements by accelerator mass spectrometry (129I AMS) [1]since 2017. In FY 2023, 512 samples of 129I were measured by preparing the AgI targets, as shown in Fig.
1. Figure 2 shows the measured blank values of AgI precipitated from carrier-reagent, called old iodine, andthe 127I beam current measured with a Faraday cup (MFC02-2) before injection to the accelerator. The
average of the 129I/127I ratio with its standard deviation (1σ) of old iodine

Blank
12%
STD
8%

is (2.5 ± 1.5) × 10−14, while the 127I beam current tends to decrease year
by year from the average current of 3.2 µA in FY2016−2017 to 0.71 µA
in FY 2023. Correspondence between beam extraction conditions andbeam current values of the ion source is shown in Fig. 3. There does not

Test
samples80%

seem to be a causal relationship between the beam current and its
reduction. Another possible cause of the beam current decrease is theFig. 1. Details of measured I
by the AMS system in fiscal 2023.
129alignment of the target position inside the ion source.

FY 2016＆2017

FY2018FY2019FY2020

FY2021

FY2022

FY2023

FY 2016＆2017

FY2018FY2019FY2020

FY2021

FY2022

FY2023

2×10-14

Fig. 2. Temporal variation of the ratio of 129I/127I of old- iodine blank values and 127I beam current.
1Kanazawa University

19

Fig. 3. Correspondence between beam extraction conditions and beam current values of the S-4 (MCSNICS) ion source.

The measured 129I/127I values were normalized by using Standard Reference Material (SRM), Purdue-1
STD (Z94-0597) and Purdue-2 STD (Z94-0596) with an 129I/127I ratio of 8.378 × 10−12 and 6.540 × 10−11 [2](the value was revised in 2014 [3]), which was provided by the Purdue Rare Isotope Measurement
Laboratory (PRIME Lab) at Purdue University, USA. The average 129I/127I ratios with its standard deviation(1σ) are (7.820 ± 0.734) × 10−12 (9.4%) and (6.117 ± 0.204) × 10−11 (3.3%) for Purdue-1 (run number 595)
and Purdue-2 (run number 54), respectively in FY2023. The ratios of (average of measured values) /(nominal value) are 0.933 and 0.935 for Purdue-1 and Purdue-2, respectively, which are in good agreement.
This work was supported in part by JSPS KAKENHI Grant Number 22H02001.
References[1] M. Matsumura et al., UTTAC Annual Report 2022, UTTAC-92 (2023) 20.
[2] P. Sharma et al., Nucl. Instrum. Meth. Phys. Res. B 123 (1997) 347.
[3] M. Caffee (Purdue University), Private communication (2014).

20

3.6

Challenges in measuring Pb-210 using accelerator mass spectrometry

H. Takahashi, K. Sasa, T. Takahashi, T. Yoshida, M. Matsumura, A. Sakaguchi
Lead-210 (210Pb) is a U-series nuclide with a half-life of 22.4 years and has been used as a chronologicaltool for the Anthropocene environmental samples. Although some methods exist for measuring 210Pb, there
is currently no method for measuring a large number of environmental samples with an activity of a few
mBq in a short period of time. To achieve rapid measurement of 210Pb in environmental samples, this study
aims to establish a method for measuring 210Pb using accelerator mass spectrometry (AMS).
Focusing on corals as environmental samples, we investigated (i) Pb concentration and separation fromcoral samples, (ii) synthesis of inorganic Pb compounds for AMS and (iii) Pb isotope measurements by
AMS. Chemical separation methods using the AG1-x8 anion exchange resin and the Pb-resin were
optimised to remove nuclides and matrices that could interfere with measurements during AMS. Synthesisof Pb compounds (αPbO, βPbO, Pb3O4, Pb(NO3)2, PbCO3 and PbF2) was attempted to obtain stable solid
inorganic salts from aqueous lead nitrate solution. Negative ion beam extraction experiments were carriedout on the synthesised Pb compounds using a Cs sputter ion
source in order to find suitable Pb compounds andextraction conditions under which high and stable beam
currents could be obtained. Furthermore, we confirmed therelationship among the acceleration voltage, the Pb positiveion charge state after electron stripping, and the Pb ion
beam transmission efficiency, as shown in Fig. 1.

Finally,

the charged particles with mass number 210 were observedwith an ionisation chamber using a sample with a known
Pb concentration (210Pb /208Pb = 10−9, 10−10).

210

The Pb separation with the AG1-x8 was able to purify
Pb with high chemical yields of more than 97%. The main
matrix and interfering nuclides were also removed by morethan 99%. On the other hand, the Pb-resin did not
sufficiently elute Pb (61.7 ± 0.7%). In attempts to synthesise
solid

Pb

compounds,

mainlyβPbO,

Pb3O4,

βPbO+Pb3O4(4:6), Pb(NO3)2, PbCO3 and PbF2 were finallysynthesised.

Pb ion charge stateFig. 1. Relationship between the Pb ion
charge state and transmission (%) in eachacceleration voltage.

As for the AMS experiments, the highest negative ion beam current with species of 208PbO2- can be
induced from Pb3O4, but the most stable current beam can be obtained from βPbO + Pb3O4(4:6). It was also
found that negative ion beam of 208PbO2- could be efficiently converted into positive ion beams of Pb5+ at
an acceleration voltage of 3 MV (Fig. 1). Finally, the correlation between the count rates and theconcentration of 210Pb was observed using the ionisation chamber.

21

3.7

Seawater circulation analysis in the Southern and Indian Oceans bycross-sectional I-129 observation

T. Matsunaka 1, M. Inoue1, S. Nagao1, Y. Inomata1, Y. Kumamoto 2, M. Matsumura, T. Takahashi,
A. Sakaguchi, K. Sasa
The Southern Ocean is suitable for detecting water masses containing anthropogenic 129I (T1/2: 15.7
million years) tracer since 129I in the Southern Ocean is 3–6 orders of magnitude lower than that in the
Northern Hemisphere. This study aimed to clarify seawater circulation in the Southern Ocean by verticalcross-sectional observations of dissolved 129I and water mass structure analysis from the Southern Ocean to
the Indian Ocean, where few studies have been conducted.
Seawater was sampled horizontally and vertically at six sites in the Southern and Indian Oceans(maximum depth: 5,230 m) during the JAMSTEC MR19-04 voyage (December 2019–February 2020) andhorizontally at 15 sites from Australia to Showa Station in Antarctica during the National Institute of Polar
Research SR21 voyage (November 2021–March 2022). After adding 1 mg of 127I carrier (Deepwater iodine,
I/ I: 1 × 10–14) per 500 ml of seawater, iodine was purified by solvent extraction, and silver iodide targets

129 127

were prepared. The 129I/127I ratio of the target was measured using an accelerator mass spectrometer andnormalized using the S-Purdue reference material(129I/127I: 8.378 × 10–12).
In the Antarctic Circumpolar Current (ACC) regionof the Southern Ocean, anthropogenic 129I was rarely
observed in the horizontal and vertical directions(maximum depth: 5,230 m) and was below the prenuclear activity level and AMS quantification limit (Fig.
1). Anthropogenic 129I was observed in the surface layerfrom the northern area of the Southern Ocean to theIndian Ocean, and the relationship between thehorizontal distribution of 129I and water temperature,salinity, and226

Ra provided information on theboundary between the Indian Ocean surface waters andthe ACC. The vertical distribution of 129I in the Indian
Ocean decreased with increasing depth from thesurface. At the southernmost site in the South Ocean,
two spike layers of 129I above pre-nuclear activity level
were identified at 201 m and 1,670 m water depths,
and an upper 129I spike was also observed in theisodensity layer at one site to the north.
1Kanazawa University
2JAMSTEC

22

Fig. 1. Surface distribution of 129I in theSouthern and Indian Oceans during 2019–
2022.

4.
MATERIALS RESEARCH

A concrete sample compressed into the 1 mm diameter drilledhole in an Al foil of 20 µm thickness, prepared for analysis ofcontained bound water by T-ERDA. −−− Report 4.2

4.1

Characterization of AlInN/AlN/GaN structures by means of positronannihilation

A. Uedono, Y. Kimura 1, T. Hoshii1, K. Kakushima1, M. Sumiya 2, M. Tsukui 3, K. Miyano3, I. Mizushima1,3,
T. Yoda1,3, K. Tsutui1
GaN transistors have been extensively studied because of their potential for high-power and RF-frequency
devices. For GaN power devices based on AlGaN/GaN heterostructure, a two-dimensional electron gas is
generated at the interface between the AlGaN layer and the GaN layer because of spontaneous andpiezoelectric polarizations. The deposition of AlxGa1−xN with x ≥ 0.3 usually starts to degrade its crystalline
quality because of a lattice mismatch between AlGaN and GaN. A lattice matched Al0.83In0.17N/GaN
heterostructure has received attention as a potential candidate for suppressing defect introduction nearheterointerfaces [1]. However, the growth of a high crystal quality AlInN layer with a high Al mole fraction
is a great challenge because of the difference in growth temperatures for AlN and InN. It was suggested thatthe device performance can be improved by inserting a thin AlN spacer layer into the interface between
AlInN and GaN layers [2]. In the present study, we used a monoenergetic positron beam, scanningtransmission electron microscope (STEM), and energy dispersive x-ray spectroscopy (EDX) to characterize
the AlInN/AlN/GaN structure [3].
The sample structure investigated was AlInN/AlN/GaN fabricated on a Si substrate. AlInN(10 nm)/AlN
structures with different thicknesses for the AlN layers (0.75, 1, 1.5, and 2 nm) were deposited using a metalorganic chemical vapor deposition (MOVPE) technique. The Al mole fraction x of the AlxIn1−xN layer wasdetermined to be 0.18 from its lattice parameters using high-resolution Rutherford backscattering
spectrometry.
Figure 1 shows high-angle annulardark-field (HAADF) STEM imagesof the AlInN/GaN, AlInN/AlN(1nm)/GaN,

and

AlInN/AlN(2nm)/GaN samples, respectively. As
shown in Fig. 1(b), a sharp interface
image between the AlN layer and the
GaN layer was obtained for the
sample with the 1-nm-thick AlN
layer, but this was not the case for theother samples [Figs. 1(a) and 1(c)].
The observed

variation

microstructure

of

in

the
the

Fig. 1. HAADF-STEM images of (a) AlInN/GaN, (b) AlInN/AlN(1nm)/GaN, and (c) AlInN/AlN(2 nm)/GaN. Depth distributions ofGa, Al, and In in those samples are shown in (d), (e), and (f),respectively.

1Tokyo Institute of Technology

2Next Generation Semiconductor Group, National Institute for Materials Science
3NuFlare Technology Inc.

23

heterointerfaces agrees with the relationship between the
thickness of the AlN layer and the electron mobility [3],suggesting that the interface roughness is one of thecauses decreasing the carrier mobility in the channel
region. The

depth

distributions

of

the

atomicconcentrations of Al, In, and Ga were measured by EDX,
and the results are shown in Figs. 1(d)−(f). For the
AlInN/GaN sample [Fig. 1(d)], the observed asymmetryof the depth profiles of Ga, Al, and In near the
AlInN/GaN interface suggests an enhanced diffusion of
Ga into the AlInN layer. By comparing the results for the
samples with and without the AlN layer, it can beconcluded that the diffusion of Ga into the AlInN layer
was suppressed by the insertion of the AlN layer.
Vacancy-type defects in the samples were probed
using the positron annihilation technique. Details of thisFig. 2. S−E relationships for AlInN/GaN andAlInN/AlN/GaN. Thicknesses of the AlN
layers are shown in the figure, where “0 nm”
refers to AlInN/GaN. Solid curves are fits tothe experimental data. The inset shows depth
distributions of S obtained from fittings.

technique are given elsewhere [4]. Figure 2 shows S values as a function of incident positron energy E for
the AlInN/GaN and AlInN/AlN/GaN samples. The dotted line shows the S value measured at E = 20 keV
for the sample without the AlInN/AlN layers, and it corresponds to the annihilation of positrons in the GaN
layer. In the S−E plots, shoulders are observed at E ≅ 2−3 keV. Because the mean implantation depth of
positrons with this energy region is 30−60 nm, the observed S value at this energy region is mainly associatedwith the annihilation of positrons implanted into the GaN layer.
The solid curves in Fig. 2 are fits to the experimental data. Here, the effect of the positron annihilation in
the AlInN and AlN layers on the S value was neglected because of their thinness and the diffusion of
positrons toward the surface. The obtained depth distributions of S are shown in the inset of Fig. 1. It can beseen that the damaged regions near the heterointerface extend up to 110−120 nm. The species of defects
causing the increase in S can be identified as Ga-vacancy-type defects such as a Ga vacancy and/or theircomplexes with N vacancies or impurities (mainly carbon). The introduction of such vacancies can be
attributed to the atomic diffusion from the GaN layer into the AlN and/or AlInN layers. Because the channel
region of carriers is located inside these defect-rich regions (110−120 nm), the defects introduced by thedeposition of the InAlN/AlN layer could act as scattering and/or trapping centers and cause degradation in
the electron mobility.
References[1] J. Kuzmik, IEEE Electron Device Lett. 22 (2001) 510.
[2] J. Q. Xie et al., Appl. Phys. Lett. 91 (2007) 132116.
[3] A. Uedono et al., Appl. Phys. Lett. 133 (2007) 225301.
[4] R. Krause-Rehberg and H. S. Leipner, Springer Series in Solid-State Sciences, vol. 127, Springer-Verlag,
Berlin, 1999.

24

4.2

Hydrogen analysis of concrete samples by T-ERDA

N. Kinoshita 1, S. Ishii, H. Kudo, H. Naramoto, M. Sataka, K. Sasa, S. Tomita
Concrete is an effective neutron shielding material used for a bioshield etc. in nuclear power plants;
however, the radioactivities produced by nuclear reactions involving neutrons accumulate in concrete duringlong-term operation of reactors. Evaluation of the distribution of the radioactivities contribute to the costestimation and planning for the decommissioning of aged nuclear power plants. In general, the overall
distribution can be estimated by combining a Monte-Carlo code such as MCNP and a radioactivity
calculation code such as ORIGEN-S. We have addressed to improve the accuracy for predicting the
distribution [1,2].
Hydrogen, a constituent element of the water molecule, is the element that most strongly reduces theenergy of neutrons. Moisture content in the concrete is difficult to be determined accurately with athermogravimeter-differential thermal analyzer (TG-DTA) due to decomposition of carbonates andevaporation of volatile elements. Prompt γ-ray analysis (PGA) can accurately analyze the moisture content,
although there is a time-consuming process to use the equipment. Alternatively, we focused on elastic recoil
detection analysis with transmission layout (T-ERDA) to analyze the hydrogen in a powder sample.
Test samples of JG-3, one of the geochemical standard references of the Geological Survey of Japan (GSJ),
were prepared by mechanical compression into a disc-shaped hole in Al foil, as shown in Fig. 1. The
diameter of the hole is 1.2−2.0 mm and the thickness of the Al foil, which also equals to the thickness of thecompressed concrete, is 20−40 µm. By measuring the weight of the concrete, the density of the compressed
concrete was estimated to be 2.5−2.7 g/cc, which agrees reasonably with the nominal density of solid
concrete 2.6 g/cc. Notably, the beam size of 8−9.5 MeV He2+ was ~0.1 mm diameter which is much lessthan the size of the disc sample. The sample was underlaid with a Ni foil of 20 or 25 µm thickness to preventthe incident He from entering the particle detector.
Figure 2 shows the energy spectrum of recoil H for incidence of 8 MeV He2+ on a concrete sample of 40µm thickness. The recoil H at the concrete surface appears at 3.5 MeV indicated by a black arrow, according
Al foil with a disc-shaped hole

8~9.5 MeV He2+
Powder sample
compressed into
the hole
Fig. 1. Setup of the concrete sample foranalysis of H by T-ERDA.

Fig. 2. Energy spectrum of recoil H from the concrete sample of
40 µm thickness, measured using 8 MeV He2+.

1Shimizu Corporation25

to the estimate using the data base SRIM. The depth scale obtained also using SRIM is indicated by red
arrows. The recoil H generated deeper than ~20 µm cannot be observed since its kinetic energy is too low topass through the Ni foil. From the H yield integrated in the depth range 0−7.75 µm, corresponding to recoilby 8−7 MeV He, the moisture content M can be determined by using the database of recoil cross sections
IBANDL in a similar manner reported previously [3]. The value of M thus obtained is (0.72±0.07)%, where
the ±0.07% uncertainty is due to the instability of the He2+ beam current. This value certainly reproduces
M=(0.9±0.1)% determined by PGA for the same concrete sample.
Figure 3 shows the hydrogen spectrum of the same concrete sample of 20 µm thickness, measured using
9.5 MeV He2+. The energies corresponding to H recoil at the surface and backsurface of the concrete sample,
estimated using SRIM, are shown by red arrows. In this case, the recoil H signals from the whole depth
range can be seen, in contrast to the case of Fig. 2. The moisture content can be determined similarly fromthe H yield integrated over the whole depth. However, to our regret, only the rough result of M=0.27−0.76%
has been obtained. The reason for such large uncertainty is the appreciable instability of the beam currentof He2+ during the measurements. Stabilization of the He ion source is an urgent issue for advanced hydrogen
analysis.
In Figs. 2 and 3, the background yield seen under the H yield is probably due to nuclear reaction products
emitted from the sample. Indeed, the background yield sensitively depends on the beam position on theconcrete surface, as shown in Fig. 4 for the typical two cases. Identification of the origin of the backgroundis now under way to find a suitable energy range of He2+ for low-background measurements.

Fig. 3. Energy spectrum of recoil H from the concrete
sample of 20 µm thickness, measured using 9.5 MeV
He2+.

Fig. 4. Typical high-background spectra measured
for two different beam positions on the JG-3 sample
of 20 µm thickness, measured using 9.5 MeV He2+.

Although several issues still remain, for example, instability of the He ion source, we have successfully
established T-ERDA to determine H content in a powder sample. We are now planning to measure moisture
contents of various kinds of concrete samples.
References[1] N. Kinoshita et al., Prog. Nucl. Ener. 131 (2021) 103597.
[2] N. Kinoshita et al., J. Radioanal. Nucl. Chem. 332 (2023) 479.
[3] H. Kudo et al., J. Phys.: Condens. Matter 34 (2022) 435902.

26

4.3

Mössbauer study of antiferromagnetic FeMnMo alloy

H. Tanimoto, Y. Maeda, E. Kita
Metals and alloys normally show a dilatation anda decrease in the modulus with increasing
temperature. On the other hand, alloys with almost
no changes in size or modulus are called “Invar” or“Elinvar” alloys. Ferromagnetic FeNi or FeNiCrsystems are widely used for the Invar and Elinvar
alloys. However, the temperature insensitivities ofthe size and modulus are diminished under external
magnetic fields. Development of antiferromagnetic
Invar and Elinvar alloys attracts great interests
because the temperature insensitivities of the size
and modulus are maintained under the external
magnetic field [1]. Masumoto et al. [2] reported
that the temperature changes in the size or modulusofantiferromagnetic

FeMn

alloysbecameconsiderably small by addition of 4d elements likeMo and Nb. But the effect of these additives on theFig. 1. Mössbauer spectra of Fe-24.4wt%Mn-3.8
wt%Mo. The observed data (+) can be fitted with one
antiferromagnetic 6-line (blue) and one nonmagnetic
single line (blue) below 370 K (purple; sum of blue
and red lines) whereas by one nonmagnetic single
line at 410 K.

properties are not well understood. In the present
study,

themagnetic

propertyoftheantiferromagnetic FeMnMo was investigated by
Mössbauer spectroscopy in addition to thetemperature change in the Young’s modulus by theanelastic measurement.

Thin sheets of FeMnMo alloy were cut from the ingots prepared by arc melting in high purity Ar
atmosphere. The sheets were ground into a reed shape and used for the anelastic measurement. Thin foils of
30 µm thick were prepared by cold-rolling and chemical etching of the thin sheets, and used for Mössbauer
spectroscopy in transmission geometry. Fig. 1 shows the Mössbauer spectra of Fe-24.4wt%Mn-3.8wt%Mo,
indicating the temperature insensitivity of the modulus between 230 and 320 K. The spectra below 370 K
can be fitted with one 6-line (antiferromagnetic γ-phase with FCC structure) and one single line
(paramagnetic ε-phase with HCP structure). The hyperfine field of the γ-phase (the splitting of the 6-line)
decreases with the increase in the temperature and the spectrum at 410 K is explained by one single line.
Néel temperature, TN of the γ-phase estimated from the temperature change in Mössbauer spectra was about
382 K and similar values were found from the magnetization and anelastic measurements. The
disappearance of magnetorestriction by the magnetic phase transformation from ferro- or antiferromagnetic
to paramagnetic is attributed to the origin Invar or Elinvar properties but the insensitive temperature range

27

of the present Fe-24.4wt%Mn-3.8wt%Mo is much lower TN. The lattice parameter of the γ-phase shows theincrease with the increase in Mo or Mn concentrations but the effects of Mo on TN or temperaturedependence in modulus seem somewhat different from those of Mn. Further study is now in progress inorder to clarify the roles of Mo and Mn on the Elinvar characteristics of FeMnMo alloys.

References[1] M. Müller, J. Magn. Magn. Mater. 78 (1989) 337.
[2] T. Masumoto et al., Mater. Trans. 58 (2017) 701.

28

4.4

Evaluation of reactively sputtered Fe oxide thin film growth with
Mössbauer spectroscopy

R. Minami, E. Kita, H. Yanagihara
Iron oxides such as spinel ferrite have a long history asmagnetic materials and have served as bulk basic materials
for soft magnetic materials, magnetic recording media andpermanent magnet materials. In recent years, applications
have expanded to electronic devices such as spintronics, andthin film growth has become an important technology for
fabrication. The previous research has shown that continuous
growth from metallic α-Fe to Fe2O3 is possible [1] when
depositing iron oxide by sputtering. The growth modechanges from metal mode to compound mode according to
the amount of O2 gas in Ar, and the products and film
formation rate change. Furthermore, there is a hysteresis ofWavelength

Fig. 1. Plasma emission spectrum in awave-length range between 200 and 1000
nm during the sputtering deposition of Fe
in Ar gas.

film formation speed, and film formation
cannot be controlled solely by gas flow rateand input power.
For the purpose of film deposition
control, we clarify the relationship among
the intensity of plasma emission spectrum(PES), film deposition rate, and products.
The 57Fe Mössbauer effect was used to
identify the product, and the emission
spectrum during film formation was
analyzedusing

principal

component

analysis to investigate the film formation
control factors [2].
By using a metal iron target, O2 gas wasintroduced as a reactive gas into Ar gas, andiron oxide thin films were deposited withRF magnetron sputtering. By using MgO
single crystal as the substrate, 14 samples
were fabricated while paying carefulattention to the oxygen flow rate andFig. 2. Mössbauer spectra of Fe-O reactively sputtered films
with low O2 flow rates.

growth mode history. Plasma emission during film formation was recorded in the wavelength range between
200 nm and 1000 nm seen in Fig. 1. The film thicknesses were approximately 50 nm, and the growth rates

29were calculated from the film thickness determined by the X-ray reflection method. 57Fe conversion electron
Mössbauer spectroscopy (CEMS) was carried out on these thin films to determine the valence of Fe atoms.
For CEMS, a RiKon5 CEMS detector (WissEL product) was used with He (1 % of iso-butane) gas mixture(Q-gas). The thin films have areas from 100 mm2 to 200 mm2.and were set into the CEMS counter. The
surfaces of the samples were connected electrically by a carbon tape to prevent charge-up of the samples.
As the flow rate was increased from zero, the products changed from α-Fe to FeO, Fe3O4, and γ-Fe2O3.
Figure 2 shows the Mössbauer spectra in the low oxygen flow region. In particular, almost single phase FeO
was fabricated at the oxygen flow rate of 0.2 sccm. For
the higher oxygen rate region, similar results as theprevious work [2] were obtained and hysteric behaviors
were also observed at the boundary region between
Fe3O4, and γ-Fe2O3, around 0.9 sccm of oxygen flow rate.
Figure 3 shows the film formation rate in the Fe3O4 andγ-Fe2O3 generation region. A hysteresis phenomenon wasobserved near the oxygen flow rate of 0.9 sccm (transition
region between metal mode and compound mode).
In order to analyze the relation between growth
conditions and the properties of produced thin films, PES
data were first pre-analyzed. The emission peak intensity

Fig. 3. O2 flow rates dependence of growth
rates. Arrows show the order of film
fabrication, and the hysteretic result is clearlyshown.

over the entire observed wavelength range was used, therefore there are a large number of emission spectra,
namely over 3000 channels. Principal component analysis was applied to reduce the dimensionality. Afternormalizing the emission spectrum as shown in Fig. 1 to the intensity per unit time, the intensity of low
intensity peaks was set to zero. The analysis determined principal component axes (PC1, PC2), and weverified whether it was possible to predict the deposition rate and valence. The preliminary analysis revealed
that the deposition rates cannot be expressed by PC1 only, but are almost expressed by PC1 and PC2. Further
increase of dimension, PC3, was not effective, meaning that the deposition rates can be expressed in 2
dimensions, PC1 and PC2. In the valence evaluation, there were clear regions of composition in PC1 andPC2. The principal component analysis can drastically reduce the dimension of data channels from hundreds
to 2. It is found that the principal component analysis has potential in controlling sputtering film fabrications.
Authors would like to express their thanks to Prof. K. Mibu of Nagoya Institute of Technology for hiskind advises to CEMS experiments.
References[1] H. Yanagihara et al., J. Phys. D 46 (2013) 175004.
[2] R. Minami et al., [25a-12F-2], The 71st JSAP (Japan Society of Applied Physics) Spring Meeting, March
22-25, 2024, Setagaya, Tokyo.

30

4.5

Mössbauer study of an iron-based nanocrystalline alloy after annealing
in magnetic fields with various temperatures

R. Onodera 1, K. Takahashi 2, E. Kita
An iron-based nanocrystalline alloy, which is obtained byannealing of an iron-based amorphous alloy, has been
attracting attention as a soft-magnetic core material for power
inductor and transformer because of their high saturation
magnetic flux density Bs and low coercivity Hc. In order toimprove the magnetic properties, it is necessary, for example,
to decrease the coercivity while maintaining high Bs, andhighly control the crystallization from amorphous tonanocrystalline structure.
Figure 1 shows schematic drawing of nano-structure of aniron-based nanocrystalline alloy. It consists of nano-sized αFe crystal grains and a residual amorphous region. Improved

Fig. 1. Schematic drawing of nano-structureof an iron-based nanocrystalline alloy.

number density in the nano-structure and suppression and homogenization of grain size are desirable for the
α-Fe grains produced by crystallization. However, it is difficult to achieve such highly controlled
crystallization by a simple heat-treated process. In this study, magnetic energy is examined as a new
thermodynamic parameter that is effective in controlling crystallization of amorphous alloys by annealing
in a magnetic field.
It has been reported that the crystallization processes of iron-based amorphous alloys are influenced by
the applied magnetic field. In particular, it is known that the in-field annealing can accelerate nucleation andinduce crystallization [1,2]. On the other hand, a magnetic field strength around 20 T is required to induce
distinct crystallization, meaning that it is not possible to apply this method to any industrial process inpractice [3]. We have been investigating a method of inducing crystallization by multi-step heat treatment
in which the applied magnetic field strength can be suppressed during the in-field annealing.
The crystallization properties of amorphous alloys annealed at lower temperatures than the crystallization
temperature have been investigated, but there are no apparent differences in the XRD profiles after lowtemperature annealing. In contrast, thermal analysis revealed that the crystallization temperature decreased
by about 5 K after low-temperature annealing. In order to investigate the microscopic changes in amorphousalloys caused by such low-temperature annealing, Mössbauer spectroscopy was applied to amorphous alloys
annealed in both nonmagnetic and magnetic fields.
The sample used in this study was an untreated amorphous precursor of a nanocrystalline alloy known as
NANOMET whose iron concentration is 85-86 at% [4]. The sample was prepared to be 10×10 mm in size
from a thin ribbon of 60 mm in width and 17 µm in thickness. The crystallization temperature Tx evaluated
1National Institute of Technology, Ibaraki College

2Institute for Materials Research, Tohoku University

31

by using a differential scanning calorimeter (DSC) was 658 K at a heating rate of 10 K/min.
The heat treatment was carried out using a cryogen-free superconducting magnet and an electric furnace
for in-field heat treatment at High Field Laboratory for Superconducting Materials, Institute for Materials
Research,

TohokuUniversity.

Theannealing

temperature was chosen to be a sufficiently low
temperature at which crystallization does not occur.
Mössbauer spectroscopy was performed at room
temperature for sample pieces cut into 10 × 10 mmfrom the ribbon. Conventional constant acceleration(a)mode was used for measurements with a velocity
range of ±12 mm/s. The velocity was calibrated via
α-Fe at room temperature.
Figure 2 shows spectra for different stages during
the sample preparation. A spectrum for the sample in(b)

the as-quenched amorphous stage is displayed as (a),showing a typical spectrum of iron-based amorphous
structure with an asymmetric pattern. No trace ofiron oxides was detected in all samples. The
spectrum does not change much after annealing
sufficiently below the crystallization temperature,
592 K(0.9Tx), at 0 T (see (b)). When the sample wasannealed above the crystallization temperature 700(c)

K (c), the spectrum shows a clear trace of α-Fe witha residual amorphous part in a crystallized sample.
To understand the small change in the structure ofalloys with annealing under magnetic fields, ananalysis proving distribution in hyperfine field will
be effective.
References[1] H. Fujii et al., Philos. Mag. Lett. 86 (2006) 113.
[2] R. Onodera et al., J. Alloys Comp. 637 (2015) 213.
[3] R. Onodera et al., J. Alloys Comp. 604 (2014) 8.
[4] A. Makino et al., J. Appl. Phys. 109 (2011) 07A302.

32

Fig. 2. Mössbauer spectra of (a) as-Q, (b) annealed
at low temperature, and (c) crystallized samples.

4.6

Mössbauer study of superparamagnetic iron oxide nanoparticles

E. Kita, R. Onodera1, H. Mamiya2, T. Ogawa3, T. Sekido, H. Yanagihara
Magnetic properties of nanoparticles (NPs) had been studied for a long time because these show drasticchange owing to their size and have developed novel applications in addition to their conventional
applications. For example, bio-medical application has been widely spread for such as a medical field of
therapy and diagnostics, including magnetic NP hyperthermia, Magnetic Particle Imaging (MPI) andcontrast agencies for magnetic resonance imaging (MRI). The contrast agency for MRI has already been inpractical use and commercially available. To understand the specification for these applications, basic
physical properties of MNPs must be carefully investigated.
Magnetic property of nano-particles is described by super-paramagnetism (SPM) due to a time dependent
magnetization behavior against an external magnetic field, so called as relaxation phenomena. However,relaxation phenomena are quite different when the particle sizes are not mono-dispersed. Major relaxation
mechanism of SPM particles is Néel mechanism in which thermal relaxation of magnetization in a small
particle is responsible. The characteristic time of Néel mechanism 𝜏
𝜏 =

√
√

𝜏

exp(𝜎),(1)

where 𝜎 = 𝐾𝑉/(𝑘 𝑇) and 𝜏 = 10
shows the calculated 𝜏
10[Jm-3],[JK−1]. It is clear that 𝜏s [1]. Table 1

based on eq. (1) providing 𝐾 =𝑇 = 300 [K]. Here,is expressed as,

𝑘 = 1.38 × 10

is changed from an order of 10−24−3s to 10 s when the volume of nano-particle increases by 8times. This calculation supports large change in 𝜏 .
To investigate a frequency-dependent magnetic property,

Table 1. 𝜏 calculated for a cube with aside of a nm.
a [nm]

Volume [m3]

10

10−24

6.4 × 10−24

12.6

2 ×10−24

5.0 × 10−9

15.8

4 ×10−24

4.5 × 10−720

8 ×10−24

1.9 × 10−3𝜏(s)an AC magnetometry has been often utilized where themagnetization responds to an AC external magnetic field. The
frequency of the AC magnetic field ranges from 1 Hz to 10
kHz for commercial susceptometers. For those, thecorresponding relaxation time is from 1 s to 10−4 s. Mössbauer
spectroscopy (MS) has a measuring time as fast as 10−6 s andinformation on relaxation at the time scale can be obtained

Fig. 1. TEM photo of nanoparticles.

and narrow range of measuring time can be covered bychanging the sample temperature. In order to make the relaxation behavior clear, we have studied acommercially available magnetic fluid (Resovist, product of Fujifilm RI Pharma) with MS measurements[2]. Resovist was a water-based suspension of superparamagnetic iron oxide (SPIO) NPs and the structure

1National Institute of Technology, Ibaraki College
2National Institute for Materials Science
3Tohoku University

33was not simple in order to stabilize their dispersity as suspension [3].
We choose the simpler structure of nanoparticle system than
Resovist to avoid the influence of size distribution. The
nanoparticle sample was provided by Future Materials Inc.
TEM photo of the nanoparticles is shown in Fig. 1. The mean
diameter of SPIO nanoparticles is 5.11 nm with a standard
deviation of 1.37 nm. The toluene-based dispersion of the
Fe3O4 nano particles and dried NPs were utilized formeasurements. For the MS measurement, a sample holder
made of a 2 mm thick Pb plate with a 10-mm diameter hole atthe center was used, as shown in Fig. 2. The sample of 20 mg
was placed into the hole and was immobilized by raising thetemperature up to 70°C with mixing a paraffin wax of

Fig. 2. The sample holder. The Pb sample
plate has a hole of 10 mm in diameter forthe sample space.

which the melting temperature is 60°C. The temperature in
the measurements ranged between room temperature and
10 K by using a closed cycle refrigerator [1].
Mössbauer spectra recorded at temperatures from room
temperature to 10 K are shown in Fig. 3. The peak intensityof 0.5% at room temperature is remarkably small comparedwith those of lower temperatures. The peak intensity was
3.6% at 250 K and reached 7% at 200 K. It was still smalleven at 250 K. This may be due to the fixing of the sample
by the paraffin wax and the sample was not wellimmobilized near room temperature. Rigid support wasestablished at 200 K. At 10 K, the spectrum was assigned
to be that of maghemite. Between 30 K and 100 K,
Mössbauer spectra showed patterns originated from atypically thermal-fluctuated magnetic state [3]. Comparedwith the spectra of Resovist, the temperature range with aspectrum showing a clear fluctuation is shifted to lower andthe temperature dependence of MS has a similar trend. An

Fig. 3. Mössbauer spectra of SPIO NPs.

ideal spectrum from mono-dispersed particles cannot be detected and one with superposition of bimodal
particle sizes is observed. From the result, the size distribution affects much on the magnetic relaxation evenin the simple shaped sample seen in Fig. 1.
References[1] P. C. Fannin, S. W. Charles, J. Phys. D: Appl. Phys. 27 (1994) 185.
[2] E. Kita et al., UTTAC Annual Report 2020, UTTAC-90 (2021) 36.
[3] E. Kita et al., IEEE Mag. Lett. 14 (2023) 6100205.

34

4.7

Operando NRA on all-solid-state Li ion battery using 7Li isotope

N. Kishi, S. Kobayashi 1, R. Shimizu1, T. Hitosugi1, D. Sekiba
All-solid-state Li ion batteries, which can safely increase the capacity of Li-ion batteries, have attracted
much attention. At present, the problem of insufficient conductivity remains for practical use. In order tounderstand the origin of this problem, we observed the behavior of Li in the battery using 7Li (p, α) 4He
nuclear reaction analysis (NRA). Here, the natural abundance of Li isotopes is as follows: 7Li (92.4%), 6Li(7.6%), and we note that the above NRA observes only 7Li. So far, we have studied the all-solid-state Li ion
battery as a sample, which has a simple structure but is practical enough. The sample consists of a stacked
layer of Li (1.5 μm)/Li3PO4 (1.5 μm)/Au (100 nm) deposited on a Si3N4 membrane with 100 nm thickness,
as shown in Fig. 1. The Si3N4 membrane is supported on a Si wafer. The Li layer, Li3PO4 layer, and Au layer
correspond to the negative electrode, electrolyte, and positive electrode, respectively.
In the previous study, it was difficult to visualize the Li behavior at the interface between the negativeelectrode and the electrolyte, because both of these two layers contain Li [1]. In the present study, we
prepared the electrolyte (Li3PO4) using the 6Li isotope, which is invisible in our NRA method. It was
expected that the use of 6Li for electrolyte allows us to trace only the 7Li isotope, which departs from thenegative electrode (pure Li layer) and migrates into the electrolyte. The results were, however, muchdifferent from our expectations.
NRA was performed using a 1.5 MeV H+ beam from 1 MV Tandetron at UTTAC. A schematic of the
setup is shown in Fig.1. The Si surface detector (SSD) was set at θe = 150° with respect to the incident beam
direction. The emitted α due to the (p, α) reaction and backscattered H+ were detected by the SSD. The
surface normal of sample is oriented at θtilt = 30° from the beam axis, so that the escape angle of α withrespect to the surface normal is φe = 60°. We note that the H+ beam was incident from the substrate (Si3N4
membrane) side following the previous study [1].

Fig. 1. Sample structure and experimental arrangement of NRA.

The procedure of NRA measurements was as follows. At first, the bias voltage of +5.0 V was applied tothe positive electrode (the Au layer) of the as-deposited sample (battery) to make the battery as the charged

1The University of Tokyo

35

state. Then the first NRA measurement was carried out (see the blue line in Fig. 2 (a)). Next, the sample wasdischarged by reducing the bias voltage down to +0.1 V. We took the second NRA profile on this stage (seethe red line in Fig. 2 (a)). Thus, we compared the 7Li distribution before and after discharge of the battery.
Similarly, the behavior of 7Li was observed when the battery was recharged by taking the NRA profile withsweeping the bias voltage from +0.1 V to +5.0 V.

Fig. 2. (a) The NRA profiles before (blue) and after (red) the discharge process of battery (sample).
(b) The NRA profiles before (red) and after (blue) the recharge process of battery.

In the blue line in Fig. 2 (a), we notice that 7Li is distributed throughout the sample even for the asdeposited sample. This implies that the diffusion and/or intermixing of 7Li and 6Li in 6Li3PO4 occurs quickly
even at the room temperature. Therefore, the expected sharp interface between the negative electrode (7Li
layer) and the electrolyte (6Li3PO4) was not well observed. The interface is, however, still observed aroundthe channel number of 2450 in Fig. 2 (a) and also in (b). From this fact, we deduce that the solid electrolyte
consists of Lix and Li3-xPO4. In other words, it is a combination of the mobile Lix atoms (or ions) and thestiff framework of Li3-xPO4. The freely mobile Li atoms (or ions) in the electrolyte can be easily replacedby the Li atoms (or ions) from the negative electrode. Meanwhile, this phenomenon signifies that theretention of the electric power at the charged state with this combination of the negative electrode and theelectrolyte is not easy at the room temperature.
Finally, we discuss on the results taken on the charged and discharged states of samples in short. Withdecreasing the bias voltage down to 0.1 V, the peak at the negative electrode disappears and the migrationof 7Li into the positive electrode (Au layer) is seen. The recharge process is rather simple, i.e., the Au-Li
alloy shows the partial decomposition and the considerable amount of Li returns to the negative electrode.
The details of the whole movements of atoms, including P and O, must be clarified from the simultaneous
analysis by Rutherford backscattering spectrometry (RBS) and NRA.
Reference[1] N. Kishi et al, UTTAC Annual Report 2022, UTTAC-92 (2023) 33.

36

4.8

Development of a rotational sample holder for ERDA on Fomblin oil
surfaces

D. Sekiba, K. Yamamoto, S. Kawasaki 1, K. Mishima1
For the purpose to keep and transport the ultra-cold neutron (UCN) more efficiently, the Fomblin oil
coating on the walls of vacuum chambers and vacuum ducts attracts much attention [1]. Fomblin is a kindof fluorine-based oils, which does not stoichiometrically include hydrogen. While the Fomblin oil coating
is expected to decrease the absorption cross section of walls for UCN, the direct measurements of hydrogenamount on the Fomblin oil surfaces have not been made in the past.
In order to determine the hydrogen concentration on the Fomblin oil surfaces, we developed a rotational
sample holder for elastic recoil detection analysis (ERDA). In the design, a previously reported idea forhigh-resolution Rutherford backscattering spectroscopy (RBS) on an ionic liquid is adopted [2]. In thepresent study, we examined influence from the rotation (electric noises from the stepping motor and/or
vibrational noises due to the looseness of mechanics) on the RBS and ERDA spectra.
Figure 1 shows the photograph of the developed rotational sample holder of 80 mm diameter. The wheel
part is made of Al-based alloy (duralumin), and it is coated by the Au thin film with a thickness of 50 nm.
The lower part of wheel is inserted into a small pool for oil. In the present study the measurements werecarried out with leaving the pool empty. The simultaneous RBS and ERDA were performed with 2.5 MeV
4He2+ at the D-course in 1MV Tandetron at UTTAC. The arrangement of the sample holder with respect tothe incident beam is shown in Fig. 2. Details of the detector setup are described in our previous paper [3].
For the measurement with the rotation, the rotational speed was set at 3 rpm.

Fig. 2. Setup for simultaneous RBS and ERDA.

Fig. 1. A photograph of the rotational

SSD stands for the B-implanted silicon surface-sample holder.

barrier detector.

1 High Energy Accelerator Research Organization (KEK)37

Figure 3 (a) and (b) show the obtained RBS and ERDA spectra, respectively. The blue and red lines
correspond to the measurements with and without the rotation of the sample holder, respectively. In the RBS
spectra we can find the leading edge corresponding to Al (~ 500 ch) and a peak of Au (~ 900 ch). On theother hand, there are two peaks at ~700 ch and ~800 ch in the ERDA spectra. It is reasonable to assign themto the hydrogen at the interface between the duralumin substrate and the Au layer and the hydrogen on thesurface of Au layer. We did not find any significant changes due to the rotation within the statistical errors.
As a next step, we will make the RBS and ERDA measurements on the Fomblin oil surfaces.

Fig. 3. (a) The RBS spectra taken on the rotational wheel with (blue) and without (red)rotation. (b) The ERDA spectra on the rotational wheel with (blue) and without (red) rotation.

References[1] A. Serebrov et al., J RES NATL INST STAN. 110 (2005) 333.
[2] K. Nakajima et al., Nucl. Instrum. Methods Phys. Res. B 267 (2009) 605.
[3] D. Sekiba et al., J. Appl. Phys. 106 (2009) 114912.

38

5.
ION-BEAM IRRADIATION EFFECT

Samples fixed on the A5-sized holder for ion
beam irradiation experiments.

5.1

Fabrication and functional development of one-dimensional organic
nanostructures using high-energy charged particles

M. Nobuoka1, A. Taguchi1, N. Miyake1, W. Choi1, S. Seki 1
Today's digital society has flourished to the point where it is no exaggeration to say that it is backed by
the improvement of semiconductor microfabrication technology. While the miniaturization ofsemiconductors on the order of several nm, which is in the atomic domain, is just around the corner, it issaid that the limitations of the fabrication method and material structure have begun to appear. In addition,
in recent years, organic devices such as organic electroluminescence (EL) have already reached the stage ofpractical use, and they are expected to play a role in the next-generation semiconductor industry due to theirversatile material selectivity. Therefore, the fabrication of organic nanomaterials to replace conventional
inorganic materials and the establishment of fabrication technologies for such materials will be an immediatechallenge, even in light of the recent SDGs.
The

one-dimensionalorganic

nanomaterials:

nanowires fabricated by using energetic charged
particles are based on the original technique that wehave reported for a long time as SPNT (Single

Particle Nanofabrication Technique) or STLiP(Single-particle Triggered Linear Polymerization)
method (Fig. 1) [1,2]. The charged particles withkinetic energies of MeV-GeV travel through thematerial and form a cylindrical high-density activatedregion along their trajectory: ion track. In particular,
excited and ionized states in ion tracks in organic
materials, which are the starting points of chemical

Fig. 1. Illustration of ion track in the organic materials,
and SPNT and/or STLiP method.

reactions, are densely formed and polymerization
and/or cross-linking reactions between each organic
molecule proceed continuously. The insoluble gel-like
one-dimensional structures formed in this way can beisolated as so-called organic nanowires, and we havereported two kinds of macrostructure in the nanowires
obtained by different isolation methods [3] (Fig. 2).
Vertically aligned nanowire array structures, in which
flexible organic nanowires are freestanding on a support
substrate, are expected to lead to the development oforganic devices in multiple fields, which have not been

1Kyoto University

39

Fig. 2. Schematic illustration of nanowire isolationand its morphology (wet and/or dry process) in
STLiP method.

feasible until now. In this project, we targeted various small organic molecules and polymers, to 1) createorganic-inorganic hybrid nanomaterials, and 2) fabricate highly functional polymeric membranes.
Organic-inorganic hybrid nanowires
Polyhedral Oligomeric Silsesquioxanes (POSSs) are organic-inorganic hybrid molecules with organicside chains introduced into the Si-O framework, which exhibits solubility, thermal and thermo-mechanicalproperties, mechanical strength, optical permeability, gas permeability, dielectric constant, flame resistance,and many other physical properties. POSS films were deposited on silicon substrates by vacuum deposition
and irradiated with Au beams (72-90 MeV) generated by the tandem accelerator at UTTAC. After irradiation,
the samples were heated at 200°C in a high vacuum tosuccessfully isolate vertically aligned nanowires (Fig. 3).

R
R

It was observed that the ease of nanowire formation
varies depending on the different types of side chains.

optical fibers is being investigated by taking advantageof their high dielectric properties and high lighttransmittance.

Si

O

Si
O

Si
R

Si

O

O R
Si
O

The nanowires are assumed to be approximately glasslike, and their application to optical waveguides and

O

Si
O

R O
O

O
O

Si

R

Si

O

R

R

Fig. 3. Organic-inorganic hybrid nanowires. (a)molecular structure of POSS. (b) scanning electron
microscope (SEM) tilted image of POSS-derived
nanowires.

Ion beam modification of fluorinated polymers to incorporate new functions
Recently, nanochannels with densely fluorous interior surfaces were fabricated by supramolecularpolymerization [4]. These nanochannels permeate water at an unprecedentedly high rate with a nearly
perfect desalination, originating from the electrostatically negative fluorous interior surface, which canbreak water clusters to enhance the water permeability and can also provide a powerful electrostatic barrier
for the incorporation of Cl−. We have attempted to fabricate membranes with a dense array of fluorous
nanochannels in the same direction. Poly(vinylidene fluoride) (PVDF) films (KUREHA CORPORATION,
thickness: 28 μm) were irradiated with Au beams (72-90
MeV) and then treated with XeF2 exposure. By using electron
spin resonance (ESR), it was confirmed that the radicals
generated in the thin film by ion beam irradiation are
eliminated by the XeF2 treatment (Fig. 4). We plan tosystematically evaluate whether the nano-channels that may
have been formed in the thin films are highly fluorinated, andtheir water permeability.
References[1] S. Sakaguchi et al., Quantum Beam Sci. 4 (2020) 7.
[2] Y. Takeshita et al., Adv. Mater. Lett. 6 (2015) 99.
[3] K. Kamiya et al., Nat. Commun. 12 (2021) 4025.
[4] Y. Itoh, et al., Science 376 (2022) 738.

40

Fig. 4. ESR spectra of irradiated PVDF films(upper) before and (lower) after exposing to
XeF2.

5.2

Morphology of the tracks of several-tens-MeV Au ions in YBa2Cu3O7-x
studied by cross-sectional transmission electron microscopy

H. Matsui 1, I. Yamaguchi1
To accelerate the development of high-performance superconducting wires, vortex-pinning enhancement
effects by ion irradiation have been extensively studied, particularly in candidate compounds, e.g.,
YBa2Cu3O7-x (YBCO) and iron-based superconductors. Potential benefit of broken (segmented) columnar
pinning centers (pins) has been a target of debate, and has provoked interest in low electronic energy loss(Se) conditions (< 20 keV/nm in YBCO) where discontinuous or dotted 1D irradiation damage can beintentionally created instead of continuous 1D ones in the higher Se regime. However, in YBCO, detailed
morphology of such quasi 1D irradiation damage by low-Se irradiation has not been well clarified bytransmission electron microscopy (TEM). Regarding damage diameter (d) for example, the early evidence
from TEM and critical-temperature (Tc) measurements suggested a constantly increasing dependence of don Se [i.e., d(Se)] from d ~ 1 nm at Se = 13 keV/nm up to d ~ 10 nm at Se = 40 keV/nm (dashed line in Fig.
1a). However, recent cross-sectional TEM studies revealed 1D arrays of large spherical irradiation damage
in Se < 20 keV/nm. Furthermore, d in this case remarkably deviates from the conventional d(Se) trend(squares in Fig. 1a). To correctly conduct vortex pinning engineering in YBCO using low-Se ions, it isessential to understand intrinsic d(Se) in the low-Se region via detailed TEM evidence.
In this study [1], we performed high-resolution cross-sectional TEM measurements on YBCO thin films
irradiated with 44-, 66-, and 84-MeV Au ions. The Se (=11.6, 16.7, and 20.1 keV/nm) from SRIM code isnear the onset of ion-track formation which was previously determined by plan-view TEM and Tcmeasurements (about 13 keV/nm). YBCO epitaxial films on CeO2-buffered SrTiO3 substrates (Tc = 90.1 K)◀ Fig. 1. (a) Electronic-energy-loss (Se) dependence of ion-track diameter d in YBCO. Dashed line shows the generaltrend of open symbols that are early evidence from TEM and
Tc measurements [Toulemonde et al., Nucl. Instrum.
Methods Phys. Res. B 91 (1994) 108; Zhu et al., Phys. Rev.
B 48 (1993) 6436]. Blue squares are recent cross-sectional
TEM data [Suvorova et al., J. Appl. Phys. 126 (2019)
145106]. The inset explains our definition of two “local”
diameters of irradiation damage. (b) Se dependence of
maximum Jc at self-field and 77 K in our YBCO films
obtained after Au irradiation in the dose range of 1×109−
1×1012 cm-2. The dashed line indicates the upper-limit of asgrown samples. Numbers in parentheses are Ei of Au ions in
MeV.

1National Institute of Advanced Industrial Science and Technology (AIST)

41

were deposited by fluorine-free metal-organic deposition. The Au-ion irradiation was performed in a
vacuum of 1×10-6 Torr at room temperature with a 6-MV tandem accelerator at the University of Tsukuba.
The incident angle of ions was set normal to the film surface. The microstructure of the Au-irradiated YBCO
films was evaluated using cross-sectional TEM images obtained with a JEOL JEM-2100F, at an acceleration
voltage of 200 kV.
As shown in Fig. 2, we observed that the defect morphology changes from 1D arrays of spheres of about
d = 5 to 10 nm in 44-MeV irradiation to their elongated variant (spheroid) statistically pierced by thin-linesof d = 1 to 2 nm and 3 to 5 nm in 66 and 84 MeV, respectively. This means that the thin-line damage appearedat the previous onset Se of ion track formation, while the spherical damage appeared at Se lower than theonset. We found that the “local” d values estimated within the thin-line segments in the tracks follow theconventional d(Se) trend (Fig. 1a), meaning that the trend holds over the entire Se range, including therecently controversial Se < 20 keV/nm, if we ignore the spheroid segments in the tracks.
We also found that the critical current densities (Jc) at self-field and 77 K in our YBCO films are enhancedby the Au irradiation at 55 MeV or higher, but not at 44 MeV or lower. This sharp variation in the width ofirradiation-induced Jc with changing the incident ion energy (Ei) is correspondent well with the appearanceof the thin-line damage (irradiation between 44- and 66-MeV).

Fig. 2. Cross-sectional TEM data of YBCO films irradiated with (a-d) 44-, (e-h) 66-, and (i-l) 84-MeV Au ions.

Reference[1] H. Matsui and I. Yamaguchi, Nucl. Instrum. Methods Phys. Res. B 547 (2024) 165185.

42

5.3

Acquiring fundamental data for radiation protection of COTS-Grade
FPGAs

H. Kukita1, E. Miyazaki,2 T. Shiobara1, T. Kimura1
The Japan Aerospace Exploration Agency (JAXA) and Nippon Dempa Kogyo Co., Ltd. (NDK) arecurrently conducting joint research and development of a flight model for demonstrations in LEO (Low
Earth Orbit) [1].
For development of the initial prototype BBM (breadboard model), we selected a COTS (Commercial
Off-The-Shelf) grade SoC-FPGA (System on a Chip Field-Programmable Gate Array). For the selected
SoC-FPGA, a radiation resistance performance test was conducted in FY2022, thereby we confirmed that afunction stop error is caused by SEU (Single Event Upset) but this error cannot be corrected by the ECC(Error-Correcting Code) function. We determined that ECC is insufficient for the space application of COTgrade SoC-FPGAs, hence implemented additional radiation countermeasures such as adding an SEM (Soft
Error Mitigation) function and improving the scrubbing cycle. Then, we reconfirmed the soft error
occurrence status. The beam irradiation tests were conducted using the UTTAC's 6MV tandem accelerator.
Test results (June 2023)
Beam irradiation tests with 12 MeV H+, 24 MeV Li3+, 36 MeV B5+, 42 MeV C6+, and 54 MeV O8+
were conducted.
Ion

Irradiation energy

Results

H+

12 MeV

Error Free

Li3+

24 MeV

Functional interrupt occurred with uncorrectable CRAM,
BRAM and LUT errors

B5+

36 MeV

Same as above

C6+

42 MeV

Same as above

O8+

54 MeV

Same as above

Note: Frequency of occurrence varies.
CRAM (Configuration RAM)：Memory area where circuit wiring information is set.
BRAM (Block RAM)：Memory area used for storing user-designed programs, data, andparameter coefficients, etc.
LUT (Look Up Table)：The part of the FPGA internal circuit that implements truth tables torealize combinational circuit functions, coefficient functions in signal processing circuits,etc., and are consisted with SRAM elements in some cases.

1Nihon Dempa Kogyo Co., Ltd.
2Japan Aerospace Exploration Agency

43

Through detailed analysis of the above test results, we found that when two or more non-adjacentsimultaneous errors occur, the error correction function does not work properly and the component stops
functioning, leading to the SEFI (Single Event Functional Interrupt) condition.
To deal with this issue, it is necessary to take two countermeasures. One is for the architecture of the
FPGA device itself such as CRAM, BRAM, SRAM circuit structure in the LUT section, flip-flops, and theother is for system soft error for the user logic section including the CPU. We are modifying our design. We
plan to conduct another radiation evaluation after applying these countermeasures.
Reference[1] Nihon Dempa Kogyo Co., Ltd. (NDK) and JAXA have started co-creation activities related to "Projectto Create a New QCM sensor for Space Flight".
https://www.ndk.com/en/news/upload/NDK_JAXA_20240208_en.pdf
https://global.jaxa.jp/press/2024/02/20240208-1_e.html

44

6.
TECHNICAL REPORT

Improvement of the vacuum monitoring system at thehigh voltage terminal of the 6MV tandem accelerator.

6.1

Accelerator maintenance 2023

T. Moriguchi, T. Yoshida, Y. Yamato, S. Ishii, T. Takahashi, M. Matsumura, T. Nakazawa, K. Sasa
Recovery of the terminal vacuum gauge
The vacuum gauge installed at the high-voltage terminal in FY2022 [1] could not be operated around
June 2023. During the regular maintenance with the tank opened in March 2024, the cause was found to bebroken plastic optical fibers (POFs) caused by sparks (Fig. 1 (a)). As shown in Fig. 1 (b), we rewired thePOFs to maintain the distance between them with conductive tape. To prevent spark damage to electronics
in the terminal, band-shaped contacts were mounted inside the terminal shell (Fig. 1 (c)). After the regular
maintenance inside of the tank, we confirmed operation of the terminal vacuum gauge (Fig. 1 (d)). Using
the terminal vacuum gauge, we found that the terminal vacuum could potentially be used as a beam transportindex because the terminal vacuum depends on the transport efficiency through the 6MV Pelletron tandem
accelerator.

Fig. 1. (a) Broken plastic optical fibers (POFs) indicated by red allows. (b) Rewiring of POFs using
conductive tape indicated by a red allow. (c) Band-shaped contacts mounted inside of the terminal shell.
(d) The main display for monitoring of the terminal vacuum gauge.

45

Installation of new turbomolecular pump
We added an auxiliary turbomolecular pump (TMP) to the 03 line downstream of the 6MV Pelletron
tandem accelerator (Fig. 2). Previously, with only one TMP operating from the terminal to the 03-1 valve, anumber of inadequate vacuum evacuations occurred due to some 2-inch thin piping. For this reason, a new
TMP with a displacement of 360 L/s manufactured by Leybold was added. This newly installed TMP
improved the vacuum from 6.3 × 10−8 to 2.9 × 10−8 Torr.
Replacement of a hard disk of AccelNET control system
One RAID 1 hard disk failed on the AccelNET control system computer for the 6MV Pelletron tandem
accelerator. There are five computers with RAID 1. At this issue, the alarm sounded from tsukuba1-10,
which is placed at the end of the L4 line (AMS line) in the accelerator room. When an alarm sounds, the
RAID disk is likely to fail. RAID 1 is a configuration that improves fault tolerance by writing the same data
to two hard disks. All of the AccelNET control systems use RAID 1, but only tsukuba1-10 uses a 250 GB
hard disk drive (HDD), while the others use 500 GB. We opened up tsukuba1-10 to see which hard disk had
failed, removed the failed one, installed a new HDD, rebuilt it, and put it back together (Fig. 3).

Fig. 3. Replaced RAID 1 hard disk tsukuba1-10.

Fig. 2. Newly installed TMP.

Reference[1] Y. Yamato et al., UTTAC Annual Report 2022, UTTAC-92 (2023) 47.

46

7.
LIST OF PUBLICATIONS AND PRESENTATIONS

7.1

Peer-reviewed and proceedings papers

1. A. Uedono, Y. Kimura, T. Hoshii, K. Kakushima, M. Sumiya, M. Tsukui, K. Miyano, I. Mizushima,
T. Yoda, K. Tsutsui, “Vacancy-type defects in AlInN/AlN/GaN structures probed by monoenergetic
positron beam”, J. Appl. Phys. 133 (2023) 225301(1-6) [DOI:10.1063/5.0153128].
2. M. Sumiya, O. Goto, Y. Takahara, Y. Imanaka, L.W. Sang, N. Fukuhara, T. Konno, F. Horikiri, T. Kimura,
A. Uedono, H. Fujikura, “Fabrication of AlGaN/GaN heterostructures on halide vapor phase epitaxy
AlN/SiC templates for high electron mobility transistor application”, Jpn. J. Appl. Phys. 62 (2023)
085501(1-5) [DOI:10.35848/1347-4065/ace671].
3. K. Sierakowski, R. Jakiela, P. Jaroszynski, M. Fijalkowski, T. Sochacki, M. Iwinska, M. Turek, A.
Uedono, M.A. Reshchikov, M. Bockowski, “Analysis of Zn diffusion in various crystallographic
directions of GaN grown by HVPE”, Mater. Sci. Semicond. Process. 167 (2023) 107808(1-10)[DOI:10.1016/j.mssp.2023.107808].
4. H. Okumura and A. Uedono, “Mg implantation in AlN layers on sapphire substrates”, Jpn. J. Appl. Phys.
62 (2023) 020901(1-5) [DOI:10.35848/1347-4065/acb898].
5. F. Nagano, F. Inoue, A. Phommahaxay, L. Peng, F. Chancerel, H. Naser, G. Beyer, A. Uedono, E. Beyne,
S. De Gendt, S. Iacovo, “Origin of voids at the SiO2/SiO2 and SiCN/SiCN bonding interface using
positron annihilation spectroscopy and electron spin resonance”, ECS J. Solid State Sci. Technol. 12(2023) 033002(1-5) [DOI:10.1149/2162-8777/acbe18].
6. Y. Harashima, H. Koga, Z. Ni, T. Yonehara, M. Katouda, A. Notake, H. Matsui, T. Moriya, M. K. Si, R.
Hasunuma, A. Uedono, Y. Shigeta, “Finite temperature effects on the structural stability of Si-doped
HfO2

using

first-principles

calculations”,

Appl.

Phys.

Lett.

122

(2023)

262903(1-6)[DOI:10.1063/5.0153188].
7. A. Uedono, H. Sakurai, J. Uzuhashi, T. Narita, K. Sierakowski, S. Ishibashi, S. F. Chichibu, M.
Bockowski, J. Suda, T. Ohkubo, N. Ikarashi, K. Hono, T. Kachi, “Annealing properties of vacancy-type
defects in ion implanted GaN during ultra-high-pressure annealing studied by using a monoenergetic
positron beam”, Proc. SPIE 12421, Gallium Nitride Materials and Devices XVIII, 2023, 124210C(1-7)[DOI:10.1117/12.2646233].
8. G. Zhang, H. Shen, Z. Zhao, J. Tang, L. Wang, D. Chen, L. Qi, K. Wu, X. Han, H. Ouyang, N. Wang,
X. Sun, M. He, K. Sasa, S. Jiang, “Experimental study on the charge-exchange cross-sections of lowenergy carbon ions in helium at GXNU”, Radiocarbon 2023 [DOI:10.1017/RDC.2023.44].

47

9. H. Shen, J. Tang, G. Zhang, L. Wang, D. Chen, L. Qi, K. Wu, X. Han, H. Ouyang, N. Wang, X. Sun,
M. He, K. Sasa, S. Jiang, “Radiocarbon and tritium measurements at the GXNU-AMS facility”,
Radiocarbon 2023 [DOI:10.1017/RDC.2023.31].
10. H. Matsui, G. Nishijima, A. Matsumoto, I. Yamaguchi, T. Manabe, M. Sohma, “Nonreciprocal criticalcurrent in an obliquely ion-irradiated YBa2Cu3O7 film”, Appl. Phys. Lett. 122 (2023) 172601[DOI:10.1063/5.0146885].
11. H. Matsui and I. Yamaguchi, “Fine structure of the tracks of several-tens-MeV Au ions in YBa2Cu3O7−x
studied by cross-sectional transmission electron microscopy”, Nucl. Instrum. Methods Phys. Res. B 547(2024) 165185 [DOI:10.1016/j.nimb.2023.165185].
12. E. Kita, R. Onodera, M. Kishimoto, H. Yanagihara, "Magnetic Relaxation of Superparamagnetic Fe
Oxide Particles Studied with Mössbauer Spectroscopy", IEEE Magn. Lett. 14 (2023) 6100205[DOI:10.1109/LMAG.2023.3264115].
13. S. Naimi, Y. Yamaguchi, T. Yamaguchi, A. Ozawa, “Recent achievements at the Rare-RI Ring, a uniquemass spectrometer at the RIBF/RIKEN”, Eur. Phys. J. A 59 (2023) 90 [DOI:10.1140/epja/s10050-02301009-4].

7.2

Reviews and books

1. R. Mundo, T. Matsunaka, T. Nakanowatari, Y. Taniuchi, M. Inoue, H. Kasai, K. Mashita, H. Mitsunushi,
S. Nagao, “A review of the oceanographic structure and biological productivity in the southern Okhotsk
Sea”, Prog. Oceanogr. 221 (2024) 103194 [DOI:10.1016/j.pocean.2023.103194].
2. 谷本久典,“反強磁性 FeMnMo 合金の微細組織と動的ヤング率温度変化”, 特集 金属と合金の微細組織と各種特性との対応、金属（アグネ）, 第 93 巻 12 号 (2023) 1057-1064.

7.3

Poster and oral presentations

1.

T. Moriguchi, “Reaction cross sections for proton-drip line nuclei”, Workshop at Quark-Nuclear
Matters in Tomonaga Center for the History of the Universe (TCHoU), Univ. of Tsukuba (Mar. 29,2024). (Invited Talk)

2.

矢野朝陽, 山口由高, 小沢 顕, 大西哲哉, 阿部康志, 長江大輔, Naimi Srah, 森口哲朗, 山口
貴之, Navodhayan Chndratakumar, George Hudson-Chang, 古泉 紫, 久保研吾, 佐々木健太,

48

滝浦一樹, 上坂友洋, 若杉昌徳, Zhang Hanbin, “垂直ステアリング磁石導入による稀少 RI リングのアップグレード”, 日本量子医科学会第 3 回学術大会, 理化学研究所和光キャンパス（2023 年
12 月 8−9 日）.
3.

Zhang Hanbin, 小沢 顕, 森口哲朗, 矢野朝陽, 松本 樹, “反応断面積測定における He セルを用いた固体重水素標的の開発”, 日本量子医科学会第 3 回学術大会, 理化学研究所和光キャンパス（2023 年 12 月 8−9 日）.

4.

A. Yano, A. Ozawa, T. Moriguchi, Y. Yamato, K. Tomita, N. Kaname, M. Hayashi, A. Moriyama, H.
Zhang, Y. Seki, T. Matsumoto, “Studies of the nuclear polarization of 29P via nat.Si(𝑝⃗, n) andSi(𝑑⃗, n) reactions”, International Conference on Hyperfine Interactions and their Applications

nat.

(HYPERFINE2023), Nara, Japan (Nov. 13−17, 2023).
5.

森口哲朗, “偏極イオン源を用いた核モーメント測定”、第 12 回停止・低速 RI ビームを用いた核分光研究会, 立教大学（2023 年 9 月 4−5 日）. （招待講演）

6.

矢野朝陽, 小沢 顕, 森口哲朗, 大和良広, 冨田啓介, 要 直登, 林 実香, 森山敦喜,
関 優也, Zhang Hanbin, 松本 樹, “Si 中における偏極移行反応で生成した 29P の偏極度”、第12 回停止・低速 RI ビームを用いた核分光研究会、立教大学（2023 年 9 月 4−5 日）.

7.

森口哲朗, 石井 聡, 高橋 努, 大和良広, 吉田哲郎, 松村万寿美, 中沢智幸, 笹 公和,
上殿明良, “筑波大学タンデム加速器施設 UTTAC の現状（2022 年度）”, 35 回タンデム加速器及びその周辺技術の研究会、福井県若狭湾エネルギー研究センター, 敦賀市（2023 年 6 月 22−23 日）.

8.

T. Moriguchi, R. Kagesawa, A. Ozawa, W. Horiuchi, Y. Abe, M. Amano, D. Kamioka, A. Kitagawa,
M. Mukai, D. Nagae, M. Sakaue, S. Sato, B. H. Sun, S. Suzuki, T. Suzuki, T. Yamaguchi, A. Yano,
K. Yokota, “Measurement of reaction cross section for 17F with a solid hydrogen target”, The 4thInternational Conference on Advances in Radioactive Isotope Science (ARIS2023), Avignon,
France (Jun. 4−9, 2023).

9.

A. Yano, T. Moriguchi, A. Ozawa, S. Ishimoto, M. Fukuda, M. Mihara, M. Tanaka, D. Nishimura, T.
Yamaguchi, T. Suzuki, T. Izumikawa, T. Ohtsubo, S. Sato, S. Fukuda, A. Kitagawa, M. Fukutome,
F. Hayashi, Y. Honda, N. Kaname,
Taguchi,

M. Kanda, Y. Kimura, N. Noguchi, H. Seki, S. Sugawara, R.

H. Takahashi, G. Takayama, “Development of Thick Solid Deuterium Target”, The 4thInternational Conference on Advances in Radioactive Isotope Science (ARIS2023), Avignon,
France (Jun. 4−9, 2023).

49

10. 森口哲朗, “RI ビーム飛行時間検出器の開発 - 理研稀少 RI リングのための検出器 -”, 2022 年
度 HIMAC, 共同利用研究成果発表会, オンライン開催（2023 年 5 月 30 日−6 月 1 日）.
11. 秩父重英，嶋 紘平，上殿明良，石橋章司，田中 亮，高島信也，上野勝典，江戸雅晴，
渡邉浩崇，本田善央，須田 淳，天野 浩，加地 徹，生田目俊秀，色川芳宏，小出康夫，“GaN 成長層･Mg イオン注入層の室温フォトルミネッセンス寿命 (II)”，第 71 回応用物理学会春季学術講演会，東京都市大学 (2024 年 3 月 22−25 日)．
12. 秩父重英，嶋 紘平，上殿明良，石橋章司，田中 亮，高島信也，上野勝典，江戸雅晴，
渡邉浩崇，本田善央，須田 淳，天野 浩，加地 徹，生田目俊秀，色川芳宏，小出康夫，“GaN 成長層･Mg イオン注入層の室温フォトルミネッセンス寿命 (III)”，第 71 回応用物理学会春季学術講演会，東京都市大学 (2024 年 3 月 22−25 日)．
13. 嶋 紘平，上殿明良，石橋章司，石黒 徹，秩父重英，“低圧酸性アモノサーマル成長 GaN のミッドギャップ再結合過程”，第 71 回応用物理学会春季学術講演会，東京都市大学(2024 年 3 月 22−25 日)．
14. 蛯子颯大，大西洸輝，上殿明良，Serena Iacovo，井上史大，“プラズマ活性化接合応用に向けた
SiCN 膜の特性評価”，第 84 回応用物理学会秋季学術講演会，熊本城ホール，熊本市 (2023
年 9 月 19−23 日)．
15. K. Onishi, T. Iwata, A. Uedono, F. Inoue, “Releasable direct bonding for fine pitch die to wafer hybrid
bonding” Advanced Metallization Conf., Univ. of Tokyo (Oct. 8−12, 2023).
16. H. Kitagawa, K. Onishi, J. Fuse, A. Uedono, T. Iwata, F. Inoue, “Low-temperature deposited SiO2 foradvanced chiplet”, The 244th ECS Meeting, Gothenburg, Sweden (Oct. 8−12, 2023).
17. S. Ebiko, K. Onishi, A. Uedono, S. Iacovo, F. Inoue, “A comprehensive study on chemical bonding
and open spaces with silicon carbon nitride films for direct bonding”, The 244th ECS Meeting,
Gothenburg, Sweden (Oct. 8−12, 2023).
18. R. Akaike, K. Uesugi, K. Shima, S. F. Chichibu, A. Uedono, H. Miyake, “Effect on QWs Qualities ofThickness of Homoepitaxial AlN on AlN/sapphire Prepared by Sputtering and High temperature
Annealing”, The 14th Int. Conf. Nitride Semiconductors, Fukuoka, Japan (Nov. 12−17, 2023).
19. K. P. Sierakowski, R. Jakiela, P. Jaroszynski, M. Fijalkowski, T. Sochacki, M. Iwinska, M. Turek, A.
Uedono, M. A. Reshchikov, M. Bockowskie, “Analysis of Zn diffusion in various crystallographic
directions of GaN Grown by HVPE”, The 14th Int. Conf. Nitride Semiconductors, Fukuoka, Japan(Nov. 12−17, 2023).

50

20. K. Shima, T. Narita, K. Kataoka, S. Ishibashi, A. Uedono, M. Bockowski, J. Suda, T. Kachi, S. F.
Chichibu, “Luminescence studies of Mg implanted and undoped GaN on GaN structures processedby ultra high pressure annealing”, The 14th Int. Conf. Nitride Semiconductors, Fukuoka, Japan(Nov. 12−17, 2023).
21. M. A. Reshchikov, O. Andrieiev, M. Vorobiov, K. Sierakowski, R. Jakiela, P. Jaroszynski, A. Uedono,
M. Bockowsk, “Effect of ion implantation damage on photoluminescence from GaN”, The 32nd Int.
Conf. Defects in Semiconductors, Delaware, USA (Sept. 10−15, 2023).
22. K. Shima, R. Tanaka, S. Takashima, K. Ueno, M. Edo, A. Uedono, S. Ishibashi, S. F. Chichibu,“Temporary and spatially resolved luminescence studies of p-GaN segments fabricated by vacancyguided redistribution of Mg using sequential ion implantation of Mg and N”, The 21st Int. Workshop
on Junction Technology, Kyoto, Japan (June 8−9, 2023).
23. A. Uedono, “Japanese Semiconductor Revitalization Strategy and Universities”, EURAXESS Japan,
Innovation day: Semiconductor Research and Innovation; EU, India and Japan Perspectives(Nov. 22, 2023) & Online. (Invited Talk)
24. S. F. Chichibu, A. Uedono, H. Iguchi, T. Narita, K. Kataoka, M. Bockowski, J. Suda, T. Kachi, S.
Takashima, R. Tanaka, K. Ueno, M. Edo, S. Ishibashi, K. Shima, “Impacts of vacancy clusters on theluminescence dynamics in Mg implanted GaN on GaN structures”, The 14th Int. Conf. Nitride
Semiconductors, Fukuoka, Japan (Nov. 14, 2023). (Invited Talk)
25. 上殿明良，石橋章司，“陽電子を用いたワイドギャップ半導体結晶中の点欠陥評価” ，日本結晶成長学会特別講演会「結晶評価研究の最前線」，大阪電気通信大学，大阪府(2023 年 6 月 23 日)．(招待講演)
26. K. Sasa, T. Takahashi, M. Matsumura, T. Matsunaka, A. Sakaguchi, “Accelerator Mass
Spectrometry of 36Cl and 129I at the University of Tsukuba: Analytical Techniques andApplications”, The 9th East Asia Accelerator Mass Spectrometry Symposia (EA-AMS 9), KIST,
Seoul, Republic of Korea (Nov. 22−24, 2023). (Invited Talk)
27. M. Kuwae, B. P. Finney, Z. Shi, A. Sakaguchi, N. Tsugeki, T. Omori, T. Agusa, Y. Suzuki, Y.
Yokoyama, H. Hinata, Y. Hatada, J. Inoue, K. Matsuoka, M. Shimada, H. Takahara, S. Takahashi, D.
Ueno, A. Amano, J. Tsutsumi, M. Yamamoto, K. Takemura, K. Yamada, K. Ikehara, T. Haraguchi,
S. Tims, M. Froehlich, L. K. Fifield, T. Aze, K. Sasa, T. Takahashi, M. Matsumura, Y. Tani, P. R.
Leavitt, H. Doi, T. Irino, K. Moriya, A. Hayashida, K. Hirose, H. Suzuki, Y. Saito, “The cumulative
number of anthropogenic fingerprints as a potential marker of the onset of the Anthropocene—an
example of the Beppu Bay stratigraphy”, XXI INQUA Congress, Rome, Italy (Jul. 13−20, 2023).

51

28. R. Mundo, T. Matsunaka, M. Inoue, Y. Taniuchi, H. Kasai, H. Kaeriyama, S. Miki, K. Sasa, N. Seiya,“234Th/238U & 228Ra & 129I to study the ocean-currents driven transport of dissolved polycyclicaromatic hydrocarbons (PAHs) at the southern Okhotsk Sea”, European Geosciences Union,
EGU2023, Vienna, Austria & Online (Apr. 23−28, 2023).
29. T. Matsunaka, S. Tanaka, R. Mundo, M. Ozawa, M. Inoue, T. Takikawa, M. Morita, K. Sasa, N. Tang,
S. Nagao, “Variation factor of polycyclic aromatic hydrocarbons in surface seawater of the Sea ofJapan during 2017–2022”, European Geosciences Union, EGU2023, Vienna, Austria & Online(Apr. 23−28, 2023).
30. H. Kudo, H. Naramoto, M. Sataka, S. Ishii, S. Tomita, K. Sasa, “Transmission ERDA of ubiquitousdeuterium in H-containing materials”, The 26th International Conference on Ion Beam Analysis / The
18th International Conference on Particle Induced X-ray Emission, Toyama International ConferenceCenter, Toyama, Japan (Oct. 7−13, 2023).
31. K. Sasa, M. Matsumura, T. Takahashi, “Optimization of 36Cl AMS at 6 MV”, The 26th International
Conference on Ion Beam Analysis / The 18th International Conference on Particle Induced X-ray
Emission, Toyama International Conference Center, Toyama, Japan (Oct. 7−13, 2023).
32. S. Hatada, M. Hiraga, U. Ozeki, S. Ishii, T. Takahashi, Y. Shiina, K. Sasa, S. Tomita, “Comparisonof Molecular Effects on the Convoy Electron Yield of H2+ and C2+ at 292 keV/u”, The 26th
International Conference on Ion Beam Analysis / The 18th International Conference on Particle
Induced X-ray Emission, Toyama International Conference Center, Toyama, Japan (Oct. 7−13, 2023).
33. S. Shiki, G. Fujii, S. Tomita, K. Sasa, “Particle induced X-ray emission apparatus utilizing
superconducting tunnel junction detector”, The 26th International Conference on Ion Beam Analysis/ The 18th International Conference on Particle Induced X-ray Emission, Toyama International
Conference Center, Toyama, Japan (Oct. 7−13, 2023).
34. Y. Shiina, S. Hatada, Y. Ito, N. Ishikawa, M. Matsuda, M. Imai, M. Sataka, K. Sasa, S. Tomita,“Measurement of convoy electrons under irradiation of C foils with 292keV/u O2+ ions”, The 26th
International Conference on Ion Beam Analysis / The 18th International Conference on Particle
Induced X-ray Emission, Toyama International Conference Center, Toyama, Japan (Oct. 7−13, 2023).
35. I. Harayama, Y. Hirose, D. Sekiba, “Study of cathode shape of gas ionization chamber for the
reliability of ΔE-E telescope ERDA”, The 26th International Conference on Ion Beam Analysis /The 18th International Conference on Particle Induced X-ray Emission, Toyama International
Conference Center, Toyama, Japan (Oct. 7−13, 2023).

5236. K. Horiuchi, K. Sato, R. Yagihashi, K. Sasa, M. Matsumura, T. Takahashi, H. Motoyama,“Anthropogenic 36Cl from 1950 to 1970 CE in a high-resolution ice core from eastern Dronning Maud
Land, East Antarctica”, The 9th East Asia Accelerator Mass Spectrometry Symposia (EA-AMS 9),
KIST, Seoul, Republic of Korea (Nov. 22−24, 2023).
37. M. Kuwae, B. P. Finney, Z. Shi, A. Sakaguchi, N. Tsugeki, T. Omori, T. Agusa, Y. Suzuki,
Y. Yokoyama, H. Hinata, Y. Hatada, J. Inoue, K. Matsuoka, M. Shimada, H. Takahara, S. Takahashi,
D. Ueno, A. Amano, J. Tsutsumi, M. Yamamoto, K. Takemura, K. Yamada, K. Ikehara, T. Haraguchi,
S. Tims, M. Froehlich, L. K. Fifield, T. Aze, K. Sasa, T. Takahashi, M. Matsumura, Y. Tani,
P. R. Leavitt, H. Doi, T. Irino, K. Moriya, A. Hayashida, K. Hirose, H. Suzuki, Y. Saito, “The onsetof a rapid increase in anthropogenic fingerprints in the Beppu Bay stratigraphy as a potential markerof the onset of the Anthropocene”, 日本地球惑星科学連合 2023 年大会，幕張メッセ, 千葉市(2023 年 5 月 21−26 日)．
38. 堀内一穂，佐藤健人，八木橋理子，笹 公和，松村万寿美，高橋 努，本山秀明，”東南極ドロンイ
ングモードランドの高解像度アイスコアにおける 1950〜1970 年の人為起源塩素 36”，日本地球惑星科学連合 2023 年大会，幕張メッセ, 千葉市 (2023 年 5 月 21−26 日)．
39. 吉田哲郎，大和良広，笹 公和，広田克也，古坂道弘，”VR 技術で見るタンデム加速器”，第 35
回タンデム加速器及びその周辺技術の研究会，福井県若狭湾エネルギー研究センター，敦賀市(2023 年 6 月 22−23 日).
40. 笹 公和，工藤 博，楢本 洋，左高正雄，石井 聡，冨田成夫，” 構造材料用マイクロビーム装置を用いた He ビーム透過 ERDA による水素分布測定法の開発”，第 35 回タンデム加速器及びその周辺技術の研究会，福井県若狭湾エネルギー研究センター， 敦賀市(2023 年 6 月 22−23 日).
41. 笹 公和，工藤 博，楢本 洋，左高正雄，石井 聡，冨田成夫，”8 MeV He イオンビームを用いた
透過 ERDA による水素同位体比の測定”，2023 年第 84 回応用物理学会秋季学術講演会，熊本
市 (2023 年 9 月 19−23 日)．
42. 高橋穂高，笹 公和，高橋 努，松村万寿美，坂口 綾，”加速器質量分析器を用いた 210Pb の測定法の検討”，日本放射化学会第 67 回討論会，広島大学，東広島市 (2023 年 9 月 21−23 日).
43. Shi Zhiyuan、加 三千宣、笹 公和、松村万寿美、高橋 努、高久雄一、山﨑信哉、末木啓介、
坂口 綾, “別府湾の堆積物用いた表層環境への I-129 導入史の復元，Reconstruction of 129I Input
History to the Surface Environment Using a Sediment Core from Beppu Bay”, 日本放射化学会第67 回討論会，広島大学，東広島市 (2023 年 9 月 21−23 日).

53

44. 松村万寿美，笹 公和，坂口 綾，高橋 努，末木啓介，”大気中からのヨウ素 129 降下量調査（2022 年度）”，令和 5 年度放射線安全取扱部会年次大会, 日本アイソトープ協会，富山国際会
議場，富山市 (2023 年 10 月 26−27 日)．
45. 吉田哲郎，大和良広，笹 公和，広田克也，古坂道弘，”タンデム静電加速器に関する VR 教材の開発”，第 20 回日本加速器学会年会，日本大学理工学部船橋校舎，船橋市(2023 年 8 月 29 日−9 月 1 日)．
46. 笹 公和，石井 聡，高橋 努，大和良広，吉田哲郎，松村万寿美，森口哲朗，上殿明良，”筑波大学タンデム加速器施設の現状報告”，第 20 回日本加速器学会年会，日本大学理工学部船橋
校舎，船橋市 (2023 年 8 月 29 日−9 月 1 日)．
47. 松村万寿美，笹 公和，松中哲也，高橋 努，坂口 綾，末木啓介，”大気中からのヨウ素 129 降
下量調査（2022 年度）”，アイソトープ協会 放射線安全取扱部会年次大会，富山国際会議場,
富山市 (2023 年 10 月 26−27 日).
48. 笹 公和，高橋 努, 松村万寿美，吉田哲郎, 椎根大輔，高橋穂高，坂口 綾，”6 MV タンデム加速器質量分析装置を用いた難測定核種の検出技術開発の現状”，2024 年第 71 回応用物理学会春季学術講演会，東京都市大学 (2024 年 3 月 22−25 日)．
49. 笹 公和，工藤 博，楢本 洋，左高正雄，石井 聡，冨田成夫，”マイクロ He ビーム透過弾性反跳検出法を応用した水素顕微鏡の開発”，日本原子力学会 2024 年春の年会，近畿大学，東大阪市(2024 年 3 月 26−28 日)．
50. 松村万寿美，高橋 努，吉田哲郎，松中哲也，高橋穂高，坂口 綾，笹 公和，”筑波大学 6 MV タ
ンデム加速器質量分析装置における多核種 AMS と応用研究の現状（2023 年度）”，第 24 回
AMS シンポジウム，東京大学武田ホール (2024 年 3 月 28−29 日).
51. T. Matsunaka, S. Tanaka, M. Ozawa, R. Mundo, M. Inoue, Y. Kumamoto, K. Sasa, M. Matsumura，T. Takahashi, Y. Inomata, S. Nagao, “Polycyclic aromatic hydrocarbons and iodine-129 in the Arctic
and Antarctic Oceans during 2019−2022”，K-INET International Symposium 2023 Environmental
Issues in a Post-Covid 19 Society，hybrid (Dec. 6−7, 2023).
52. 三浦 輝，松中哲也，笹 公和，坂口 綾，“加速器質量分析法を用いた放射性ヨウ素の海洋動態解明”，2023 年度放射能環境動態・影響評価ネットワーク共同研究拠点年次報告会，けんしん
郡山文化センター, 郡山市 （2024 年 2 月 27 日）．

5453. 三浦 輝，松中哲也，笹 公和，“原子力施設周辺と縁辺海・外洋における放射性ヨウ素の動態解明”，金沢大学環日本海域環境研究センター共同研究成果報告会，オンライン開催 （2024 年 3
月 8 日）.
54. 脇山義史，松村万寿美，松中哲也，平尾茂一，笹 公和，“阿武隈川および新田川における出水時の 129I 動態”, 2023 年度 ERAN 報告会，郡山市 (2024 年 2 月 27 日).
55. 大和良広, 吉田哲郎, 石井 聡, “ターミナル真空計の新設”, 第 35 回タンデム加速器及びその周辺技術の研究会, 福井県若狭湾エネルギー研究センター, 敦賀市 (2023 年 6 月 22−23 日)．
56. 大和良広, 吉田哲郎, 石井 聡, “ターミナル真空計の開発”, 第 20 回日本加速器学会年会, 日
本大学理工学部船橋校舎，船橋市 (2023 年 8 月 29 日−9 月 1 日).
57. H. Matsui and I. Yamaguchi, “Fine structure of the tracks of several-tens-MeV Au ions in
YBa2Cu3O7−x studied by cross-sectional transmission electron microscopy”, Radiation Effects in
Insulators, Fukuoka, Japan (Aug. 3−8, 2023).
58. 松井浩明，西島 元，松本明善，山口 巌，真部高明，相馬 貢, ”斜入射イオン照射 YBCO 膜の超伝導ダイオード効果” 応用物理学会, 熊本城ホール, 熊本市 (2023 年 9 月 19−23 日).
59. 前田侑貴子、谷本久典、鈴木 茂、“FeGa 単結晶の低温擬弾性特性”、2023 年日本金属学会秋期講演大会, 富山大、富山市 (2023 年 9 月 19−22 日）.
60. 椎名陽子，畑田颯太，伊藤由太，石川法人，松田 誠，今井 誠，左高正雄，笹 公和，冨田成夫，”炭素薄膜への高速 O2＋照射時のコンボイ電子収量における近接効果”，原子衝突学会第48 回年会，東京工業大学大岡山キャンパス (2023 年 11 月 25−26 日).
61. 尾関海太，矢野祐一郎，平賀真瑠古，松田和真，石井 聰，笹 公和，冨田成夫，”0°電子分光用
ビームカレントモニターの製作”，原子衝突学会第 48 回年会，東京工業大学大岡山キャンパス(2023 年 11 月 25−26 日).
62. 矢野祐一郎，尾関海太，南 健太，松田和真，石井 聰，笹 公和，冨田成夫，”高速異核分子イ
オンビームの RBS を用いた成分分析”，原子衝突学会第 48 回年会，東京工業大学大岡山キャンパス (2023 年 11 月 25−26 日).
63. 椎名陽子，畑田颯太，伊藤由太，石川法人，松田 誠，今井 誠，左高正雄，笹 公和，冨田成夫，”異核二原子分子イオン照射時のコンボイ電子収量における近接効果”，「東海・重イオン科
学シンポジウム ―タンデム加速器成果報告会―」，重イオン科学研究会、原子力科学研究所，
東海村 (2024 年 1 月 10−11 日).

55

64. 冨田成夫，”KEK-TanaeRing を用いたフラグメントイオン質量分析への取り組み”，つくば E-ring
Network 研究会，高エネルギー研究所(KEK), つくば市

(2024 年 3 月 15 日).

65. 南 麟太郎、喜多英治、柳原英人、”反応性スパッタリングにおけるプラズマ発光分析による酸化鉄薄膜成長の観察”, 応用物理学会春季学術講演会 25a-12F-2 東京都市大学世田谷キャンパ
ス (2024 年 3 月 22−25 日).
66. 茂木駿紀, 不破康裕, 長谷川拓郎, 広田克也, 星野公邦, 細川律也, 市川 豪, 猪野 隆, 岩下芳久, 北口雅暁, 古賀 淳, 松崎 俊, 三島賢二, 音野瑛俊, 關 義親, 関場大一郎, 嶋 達志,
清水春樹, 清水裕彦, 角 直幸, 角野浩史, 谷田征輝, 山下 了, 吉岡瑞樹, “J-PARC/ BL05 における中性子寿命測定実験：中性子寿命解析の結果と現状”, 日本物理学会第 78 回年次大会,
東北大学, 仙台市 （2023 年 9 月 16−19 日）
67. 市川 豪, 不破康裕, 長谷川拓郎, 広田克也, 星野公邦, 細川律也, 猪野 隆, 岩下芳久, 北口雅暁, 古賀 淳, 松崎 俊, 三島賢二, 茂木駿紀, 音野瑛俊, 關 義親, 関場大一郎, 嶋 達志,
清水春樹, 清水裕彦, 角 直幸, 角野浩史, 谷田征輝, 山下 了, 吉岡瑞樹, “J-PARC/BL05 における中性子寿命測定実験：γ 線背景事象のグローバルフィット”, 日本物理学会第 78 回年次大会, 東北大学, 仙台市 （2023 年 9 月 16−19 日）.
68. 細川律也, 不破康裕, 長谷川拓郎, 広田克也, 星野公邦, 市川 豪, 猪野 隆, 岩下芳久, 北口雅暁, 古賀 淳, 松崎 俊, 三島賢二, 茂木駿紀, 音野瑛俊, 關 義親, 関場大一郎, 嶋 達志,
清水春樹, 清水裕彦, 角 直幸, 角野浩史, 谷田征輝, 山下 了, 吉岡瑞樹, “J-PARC/BL05 における中性子寿命測定実験：高統計データを用いた信号抽出効率における系統誤差評価”, 日本物理学会 第 78 回年次大会, 東北大学, 仙台市 （2023 年 9 月 16−19 日）.
69. 茂木駿紀, 不破康裕, 長谷川拓郎, 広田克也, 星野公邦, 細川律也, 市川 豪, 家城 斉, 猪野 隆, 岩下芳久, 北口雅暁, 牧瀬 壮, 松崎 俊, 三島賢二, 森川滉己, 長倉直樹, 岡部宏紀,
音野瑛俊, 關 義親, 関場大一郎, 嶋 達志, 清水春樹, 清水裕彦, 角 直幸, 角野浩史, 谷田
征輝, 富田龍彦, 上原英晃, 山田崇人, 山下 了, 矢野浩大, 吉岡瑞樹, “J-PARC/BL05 における中性子寿命測定実験：2 つの動作ガス圧力条件での中性子寿命解析”, 日本物理学会 2024
年春季大会, 北海道大学, 札幌市 (2024 年 3 月 18−21 日).

56

7.4

UTTAC seminars

2024.1.9

Measurements of azimuthal anisotropy and quantum interference effects in √𝑠= 19.6 GeV

Au+Au collisions at RHIC-STAR experiment, Masataka Enomoto (University of Tsukuba)2024.1.9

Multiplicity dependence of W-jet production in pp collisions at √𝑠 = 13 TeV with LHCALICE, Taiga Kawaguchi (University of Tsukuba)2024.1.9

Measurements of charged pions and (anti-)protons with respect to jet axis in pp and Pb-Pb
collisions at √𝑠

2024.1.9= 5.02 TeV at LHC-ALICE, Koki Sato (University of Tsukuba)

Measurements of jet nuclear modification factor and azimuthal anisotropy in Pb-Pb collisionsat √𝑠= 5.02 TeV with the LHC-ALICE to clarify the parton energy loss mechanism in

Quark-Gluon Plasma and evaluate stopping power, Takuya Kumaoka (University of Tsukuba)2024.1.17

Fabrication and characterization of a beam profile detector with scintillation fibers and MPPC
for KEK PF-AR test beam line, Yuki Asatani (University of Tsukuba)2024.2.28

Studies of nuclear spectroscopy with stopped and slowed-down RI beams and the developmentsof their related technologies, Hideki Ueno (RIKEN Nishina Center)

57

8.
THESES

Symbol of “achievement”

Doctor thesis
MUNDO, Rodrigo(Kanazawa University)

Study on fate of polycyclic aromatic hydrocarbons in Japan's coastal andmarginal sea environment（日本の沿岸及び縁辺海域における多環芳香族
炭化水素類の動態解明研究）

Master theses
HONMA, Kouta

Degradation of carbon reinforced PFA studied by positron annihilation（陽電子消滅法を用いた炭素繊維強化 PFA の温度変化による劣化評価）

HIOKI, Ryu

Annealing properties of vacancy-type defects in GaN annealed by ultra-highpressure（Mg イオン注入 GaN の超高圧焼鈍による空孔型欠陥の焼鈍特性の研究）

TORII, Kazuma

Vacancy-type defects in AlInN/AlN/Ga structure studied by positronannihilation（陽電子消滅法による AlInN/AlN/Ga 構造中の空孔型欠陥評価）

Undergraduate theses
YANO, Yuichiro

Using Rutherford backscattering for elemental analysis of fast molecular ion
composition （RBS を用いた高速分子イオンビームの成分分析）

MINAMI, Kenta

Development of Beam Current Monitor using Rutherford Backscattering（ラザフォード後方散乱を用いたビームカレントモニターの製作）

OKANO, Taiki

Development and Modification of FPGA based Radiation Measurement
System（FPGA による放射線計測システムの開発及び改良）

58

9.
LIST OF PERSONNEL

toHigh school students are touring UTTAC's (dark) back-side
facilities, which are essential for operating the tandem
accelerators.

Tandem Accelerator Complex
K. Sasa

Director, Associate Professor

D. Sekiba

Lecturer

T. Moriguchi

Assistant Professor

S. Ishii

Mechanical Engineer

T. Nakazawa

Mechanical Engineer

T. Takahashi

Electrical Engineer

Y. YamatoElectrical Engineer

T. Yoshida

Electrical Engineer

M. Matsumura

Technical Staff

H. Muromachi

Administrative Staff

Research Members *Division of Physics
A. Ozawa

T. Moriguchi

K. Sasa

T. Yamaguchi (Saitama University [Cross appointment])
Division of Applied Physics
E. Kita

D. Sekiba

H. Yanagihara

H. Tanimoto

S. Tomita

A. Uedono

Division of Geoscience
M. Kurosawa
Division of Chemistry
A. Sakaguchi
Division of Information and Systems
T. Kameda
Staff of Open Advanced Facilities Initiative
H. KudoH. Naramoto

M. Sataka

Graduate students
Graduate School of Science and Technology*

Research members and External users and collaborators include the authors and coauthors within 3 years backfrom this fiscal year, as well as the members of research projects running at UTTAC.

59

T. Amagai

N. Kishi

Z. ShiA. YanoH. Takahashi

R. Hioki

K. Torii

K. Honma

K. Kawakami

M. Hiraga

U. Ozeki

K. Matsuda

T. Kanazawa

C. Kodaka

Y. AbeT. Takahashi

H. Tanaka

R. Minami

H. Zhang

M. TabataY. Maeda

K. Yamamoto

Undergraduates
R. Tanaka

Y. Kurihara

H. Yoshikado

G. OyaK. EndoT. Miyazaki

Y. YanoT. Matsumoto

T. Okano

K. Minami

T. AbeR. Tsuboi

E. Nishiyama

K. Yazaki

External users and collaborators*
T. Ishizuka

National Institute of Advanced Industrial Science and Technology (AIST)

S. Shiki

National Institute of Advanced Industrial Science and Technology (AIST)

H. Matsui

National Institute of Advanced Industrial Science and Technology (AIST)

T. Matsunaka

Kanazawa University

R. Mundo

Kanazawa University

S. Nagao

Kanazawa University

M. Ozawa

Kanazawa University

Y. Wakiyama

Fukushima University

H. Miura

Central Research Institute of Electric Power Industry

S. Seki

Kyoto University

M. Nobuoka

Kyoto University

W. Choi

Kyoto University

A. Taguchi

Kyoto University

N. Miyake

Kyoto University

S. Kobayashi

The University of Tokyo

G. YoshidaHigh Energy Accelerator Research Organization (KEK)

H. Matsumura

High Energy Accelerator Research Organization (KEK)

E. WatanabeHigh Energy Accelerator Research Organization (KEK)

M. IshidaHigh Energy Accelerator Research Organization (KEK)

K. TsuganeHigh Energy Accelerator Research Organization (KEK)

R. Shiobara

Japan Environment Research co., LTD.

S. Yamazaki

Japan Environment Research co., LTD.

60

K. Oishi

Japan Environment Research co., LTD.

N. Kinoshita

Shimizu Corporation

K. Sasaki

Saitama University

K. Okubo

Saitama University

Y. Koizumi

Saitama University

Y. Kikuchi

Saitama University

S. Nishizawa

Saitama University

K. Watanabe

Saitama University

N. Tomita

Saitama University

T. Suzuki

Saitama University

K. Ishiyama

Tohoku University

A. Iwase

Osaka Metropolitan University

H. UnoSHI-ATEX Co., Ltd.

T. Shiobara

Nihon Dempa Kogyo Co., Ltd.

R. Onodera

National Institute of Technology, Ibaraki College61