UTTAC-90, 2021

UTTAC
ANNUAL REPORT 2020

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

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

UTTACANNUAL REPORT 2020
April 1, 2020 − March 31, 2021

UTTAC-90, 2021

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 © 2020 by Tandem Accelerator Complex, Research Facility Center
for Science and Technology, University of Tsukuba and individual contributors.
All reports are written on authors’ responsibility and thus the editors are not liable forthe contents of the report.
Tandem Accelerator Complex, Research Facility Center for Science and Technology,
University of Tsukuba
Tennodai 1-1-1, Tsukuba, Ibaraki 305-8577, Japanannual@tac.tsukuba.ac.jp

Cover: SF6 recirculation system of the UTTAC 6MV tandem accelerator.
Since SF6 gas used for electrical isolation of high voltage is a greenhousegas, it must be recirculated without being released into the environment.

PREFACE
This annual report covers researches carried out at University of Tsukuba Tandem
Accelerator Complex (UTTAC) during the fiscal year 2020 (1 April 2020 ~ 31 March
2021). The topics include not only accelerator-based researches using the 6MV Pelletronand 1MV Tandetron accelerators, but also radioisotope-based researches employing
positron annihilation spectroscopy and Mössbauer spectroscopy. Notably, the activity inresearch and education in FY2020 was seriously influenced by COVID-19. To our regret,we had no visitors of high school students in FY2020. We hope such undesired situation
will be resolved sooner or later.
September 1, 2021
Editorial board

Graduate students performing experiments using the 6MV tandem accelerator.
Experimenters at UTTAC are obliged to wear masks until COVID-19 is gone.

-i-CONTENTS

1. ACCELERATOR AND RELATED FACILITIES
1.1

Accelerator operation FY2020 ············································································

1

1.2

Current distribution measurement of accelerated ions from the 6MV tandem accelerator········

3

1.3

Measurement of air dose rate with proton and deuteron beams········································

5

2. NUCLEAR AND ATOMIC PHYSICS
2.1 Measurement of the sign of nuclear moment for unstable nucleus 29P by using rotating
magnetic field·······························································································
2.2 A study of 𝑝⃗ + nat.Si reaction by the 6 MV tandem accelerator·······································

7
8

2.3 Production of high intensity spin polarized 19O for materials science applications················· 10
2.4 Performance test of low-pressure MWDC with 1/3-cell staggered layers··························

12

2.5 Measurement of convoy electron yield for atomic ions················································ 14

3. ACCELERATOR MASS SPECTROMETRY
3.1

Performance report of the Tsukuba 6 MV multi-nuclide AMS system in fiscal 2020··············
129

16

3.2

Measurements of

I in the Cooling Pond, Chernobyl················································

18

3.3

Surface distribution of iodine-129 in the Okhotsk Sea················································

20

3.4

The Performance of Iodine-129 AMS measurements at the University of Tsukuba (FY2020)··

21

3.5

Assessing of iodine-129 in the chemical sample preparation rooms for AMS·····················

23

3.6

129

Depth profiles of I in soil derived from the Fukushima Dai-ichi Nuclear Power
Plant··········································································································

24

4. ION-BEAM APPLICATIONS
4.1

In-operand lithium depth profiling by use of NRA··················································

26

4.2

Scanning microbeam PIXE analysis of silica glass particles released from the FDNPP········

28

4.3

Depth resolution of transmission ERDA with 8 MeV He for observation of H in solids·······

30

5. ISOTOPE APPLICATIONS
5.1
5.2

Behaviors of vacancies in Mg-implanted GaN during ultra-high-pressure annealing studied
by a monoenergetic positron beam······································································· 32
Versatile sample cooling system for Mössbauer spectroscopy using a closed-cycle
refrigerator··································································································· 34- ii -

5.3

Mössbauer study of frozen magnetic fluid, Resovist··················································

36

5.4

Mössbauer study of Co and Mn substituted ferrite fine particles····································

38

5.5

Mössbauer spectroscopy of antiferromagnetic FeMnMo alloys·····································

40

6. BEAM IRRADIATION EFFECT
6.1

Consumer LoRa device radiation resistance evaluation toward space application················

42

6.2

Study on microalgae mutagenesis with 15N-resonant nuclear reaction······························

44

7. LIST OF PUBLICATIONS AND PRESENTATIONS
7.1

Journals ····································································································

46

7.2

Reviews and books························································································

50

7.3

Poster or oral presentations at academic meetings····················································

50

7.4

UTTAC seminars·························································································

54

8. THESES··········································································································
9. LIST OF PERSONNEL·····················································································

56- iii -58

1.
ACCELERATOR AND RELATED FACILITIESControl area of the UTTAC 6MV tandem accelerator

1.1

Accelerator operation FY2020

K. Sasa, S. Ishii, Y. Tajima, T. Takahashi, Y. Yamato, M. Matsumura, T. Moriguchi
The University of Tsukuba, Tandem Accelerator Complex (UTTAC) is promoting the maintenance andoperation of a combined tandem accelerator facility consisting of the 6MV Pelletron tandem accelerator andthe 1MV Tandetron accelerator for cooperative researches both inside and outside the University. The
accelerator operations were suspended from April 16th to May 17th, 2020, in response to the state of
emergency for the COVID-19 infection. UTTAC has undertaken a variety of countermeasures to preventthe spread of COVID-19. However, some outside users refrained from accelerator experiments in fiscal
2020. The operating time of the 6MV Pelletron tandem accelerator decreased by about 28% compared tofiscal 2019 [1].
We renewed one monitoring post for neutrons in June, 2020. In addition, a chiller for cooling water was
replaced by a new one in August, 2020. We had a periodic inspection for the radiation facility in the
Radiation Hazard Prevention Act once 5 years in December, 2020. The terminal potential stabilizer (TPS)
for the 6MV Pelletron tandem accelerator was broken in March, 2021. We repaired an electronic circuit in
the TPS before FY2021 started.
1 MV 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 491.5 and 191.9 hours, respectively, during
the total service time in fiscal 2020. The total number of operation days was 51. A total of 26 research
programs was carried out and a total of 117 researchers used the 1 MV Tandetron accelerator. Figures 1 and2 show classification of the accelerated ions and of the experimental purposes, respectively. This accelerator
was maximally used for the biomedical research which occupied 41% of the beam time.

Fig. 1. Accelerated ions by the 1MV Tandetron
accelerator in fiscal 2020.

Fig. 2. Purpose of use of the 1MV Tandetron
accelerator in fiscal 2020.

1

6 MV Pelletron tandem accelerator
The 6MV Pelletron tandem accelerator has 5 negative ion sources and 12 beamlines. The operating time
and the experimental beam time of the 6 MV Pelletron tandem accelerator were 1054.5 and 811.4 hours,
respectively, during the total service time in fiscal 2020. The total number of operation days was 100. A totalof 44 research programs was carried out and a total of 295 researchers used the 6MV Pelletron tandem
accelerator. 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 purposes, respectively. The operatingtime at terminal voltages of 5 and 6 MV accounted for 84% of all the beam time. A deuteron beam wasaccelerated by the 6MV Pelletron tandem accelerator for the first time. This accelerator was used most often
for AMS which occupied 49.3% of the beam time.

Fig. 3. Beam time histogram as a function of the terminal voltage for the 6MV
Pelletron tandem accelerator in fiscal 2020.
Radiation
Resistance Test
3.9%

Developments
8.4%

IBA
（ERDA/PIXE)
15.2%

AMS
49.3%

Beam test
7.9%

Fig. 4. Accelerated ions for the 6 MV Pelletron tandem
accelerator in fiscal 2020.

Nuclearphysics
15.2%

Fig. 5. Purpose of use of the 6 MV Pelletron tandem
accelerator in fiscal 2020.

Reference[1] K. Sasa et al., UTTAC Annual Report 2019, UTTAC-89 (2020) 1.

2

1.2

Current distribution measurement of accelerated ions from the 6MV
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 [1-4]. The experimental data of the highest energies of available ions is indispensable for radiation
resistance tests of semiconductors used in space. While only weak beams are needed in the radiation
resistance tests, the beam intensity is also important for ion beam modification of materials or micro-beam
analysis of environmental samples.
In this fiscal year, Sc ion was newly tested, while Cl and Ti data were updated. We have measured beam
currents of the accelerated ions as a function of the ion charge at an acceleration voltage of 1, 3, and 6 MV.
Figure 1 shows the beam current distributions of Sc ion as a function of the ion charge at the maximum
terminal voltage of 6 MV. Argon gas and a carbon foil were used as the strippers at the 6 MV terminal. The
gas pressure was about 5 μPa, and the thickness of the carbon foil was about 5 μg/cm2. The ion current
distribution for the foil stripper shifts to higher charge state by about 3 than for the gas stripper.
100

Ion Current (nA)

foil

gas

10

1

0.1
0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

Charge State
Fig. 1. Beam current distribution of Sc ions at the terminal voltage of 6 MV. Gas andfoil strippers were used in the high voltage terminal.

We have tested negative molecular ion injection towards the high voltage terminal. In this year Sc andTi were tested. For injection of molecular ions, the accelerated ion energy cannot be determined only by theterminal voltage and the ion charge after acceleration. The maximum acceleration energies obtained in thistest using the foil stripper are 76.4 and 77.9 MeV for Sc and Ti ions, respectively.
Table 1 shows the beam current distributions of Sc and Ti ions, together with N, Al, Ca, Mo and W ionsinvestigated previously. Table 2 shows the ion charges and maximum energies obtained for injection of3

negative atomic ion at the terminal voltage of 6 MV, which have been accumulated from 2016 to 2020.
Table 1. Beam current distributions for molecular ion injection at the terminal voltage of 6
MV, which have been accumulated since 2016. The measured beam intensity is shown by thesymbols: ○: ≥ 1nA, △: ≤1nA. The data shown in red were obtained using the foil stripper.
charge
state

14
13
12
11
10
9
8
7
6
5
4
3
2
1

N

Al

Ca

△
△
△

○
○
○
○

△
○
○
○
○

△
△

Sc

Ti

△
△
○
○
○
○
○
○
○
○

△
○
○
○
○
○
○
○
○
○
○

Mo

W

△
△
○
○

△
○
○
○
○
○
○

Table 2. Summary of the acceleration tests from 2016 to 2020 for negative atomic ion injection at theterminal voltage of 6 MV. The measured beam intensities are shown by the symbols: ○: ≥ 1nA, △: ≤1nA.
The data shown in red were obtained using the foil stripper.
charge energy
(MeV)
state

14
13
12
11
10
9
8
7
6
5
4
3
2
1

90
84
78
72
66
60
54
48
42
36
30
24
18
12

H

He

Li

B

C

O

F

Al

Si

◯

◯

◯

S

Cl

I

Au

△ △ ◯
△ △ △ ◯

△
△

△

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△ △

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Ni Cu Br Ag

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References[1] M. Sataka et al., UTTAC Annual Report 2016, UTTAC-86 (2017) 9.
[2] M. Sataka et al., UTTAC Annual Report 2017, UTTAC-87 (2018) 5.
[3] M. Sataka et al., UTTAC Annual Report 2018, UTTAC-88 (2019) 5.
[4] M. Sataka et al., UTTAC Annual Report 2019, UTTAC-89 (2020) 3.

4

1.3

Measurement of air dose rate with proton and deuteron beams

T. Moriguchi, M. Matsumura, K. Sasa, S. Ishii, T. Takahashi, Y. Yamato
In accelerator facilities, it is necessary to manage the air dose rate during beam irradiation. In particular, care must be taken for accelerating proton or deuteron by the 6 MV Pelletron tandem accelerator at
UTTAC because air dose rates during their irradiation are much higher than those of other ion species.
The reason is that the maximum beam energy per nucleon is realized for proton, while the binding energyof deuteron is small compared with that of other nuclei. From the point of the radiation safety, we havemeasured air dose rates during acceleration of proton and deuteron since last FY. The details of measurement are described in Ref. [1]. As shown in Fig. 1, air dose rates were measured by three pairs of area
monitors for gamma-ray (DAM-102, Hitachi Ltd.) and neutron (DAM-251, Hitachi Ltd.). Tantalum (Ta)and carbon (C) were used as beam stoppers. Carbon stopper C1 shown in Fig. 1 is located inside theshielding wall at 425 mm from the wall surface in the vertical line room.

Experimental room
A6

A4

A5

A3
A2

A7

A1

Tantalum (Ta2), Carbon (C2)Monitor-2

Polarized ion source(PIS)
Verticalline

55°

Accelerator room

Monitor-3
Tantalum (Ta3)

Carbon (C1)

90°

L4
L3
S1

S2

S5

S3

S4

Monitor-1
Tantalum (Ta1)

40°

L2
L1

6 MVtandem

105°

SF6 storage tank

10 m

Fig. 1. Layout of the 6 MV Pelletron tandem accelerator facility. Solid arrows indicate the positionsof beam stoppers: tantalum (Ta1, Ta2, and Ta3) and carbon (C1 and C2). Dashed arrows indicate thepositions of three pairs of area monitors for gamma-ray and neutron (Monitor-1, Monitor-2, and Monitor3).

5

Figure 2 shows the measured air dose rates as a function of beam energy during irradiation of the beam
stoppers with proton and deuteron beams, together with the last FY’s results. Note that the beam current isapproximately 300 nA for proton and 30 nA for deuteron which are equal to one-tenth of the certiﬁcatedlimitation. As shown in Fig. 2 (b), air dose rates of both gamma-ray and neutron for the tantalum stopper
are lower than those for the carbon stopper except for that of neutron during proton irradiation at 10 and
12 MeV. This result suggests that carbon is an effective stopper for proton beam to reduce air dose rate ofneutron. When the 12 MeV proton beam impinges on the carbon stopper inside the shielding wall (C1),
the air dose rates measured by Monitor-2 are several µSv/h for both gamma-ray and neutron. For carbon
stopper during deuteron irradiation, the dip around 10 MeV is seen in both gamma-ray and neutron, but
the reason for this is not clear at the moment. We will continue to measure the air dose rate and improvethe management system for radiation safety at UTTAC.

(b) Monitor-2(a) Monitor-1
Air dose rateof gamma-ray (µSv/h)(c) Monitor-3

20

20

20

H (300 nA) on Ta2
H (300 nA) on C2
D (30 nA) on Ta2
D (30 nA) on C2

H (300 nA) on Ta1
D (30 nA) on Ta1

H (300 nA) on Ta3
D (30 nA) on Ta3

15

15

15

10

10

10

5

5

5

0

0

160

160

140

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120

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100

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40

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0

0

Air dose rateof neutron (µSv/h)

0
160

0

2

4

6

8

10

Energy (MeV)

12

0
0

2

4

6

8

10

12

0

Energy (MeV)

2

4

6

8

10

12

Energy (MeV)

Fig. 2. Air dose rates of gamma-ray (upper panels) and neutron (lower panels) measured by (a) Monitor-1,(b) Monitor-2, and (c) Monitor-3. These results were obtained by the nearest area monitor to the irradiatedstopper. Blue and red symbols represent the results for proton (H) of approximately 300 nA and deuteron(D) of approximately 30 nA, respectively. Circles and crosses represent the results for tantalum (Ta1, Ta2,
and Ta3) and carbon (C2) stoppers, respectively. Note that backgrounds were already subtracted.

Reference[ 1 ] T. Moriguchi et al., UTTAC Annual Report 2019, UTTAC-89 (2020) 5.

6

2.
NUCLEAR AND ATOMIC PHYSICS

Setup for measurements of nuclear magnetic moment2.1

Measurement of the sign of nuclear moment for unstable nucleus 29P byusing rotating magnetic field

A. Ozawa, K. Tomita, T. Moriguchi, Y. Yamato, N. Kaname, M. Hayashi, A. Yano
We developed rotating magnetic field system to determine the sign of nuclear magnetic moments (μ’s)
for unstable nuclei [1]. In FY2020, we have succeeded in determining the sign of μ for 29P (Iπ=1/2+). Up tonow, although the absolute value of μ for the nucleus is determined (|μ|=1.2349(3)), the sign of μ is unknown[2]. In this report, we briefly present the result.
Our rotating magnetic field system is shown in Fig. 1 in Ref. [3]. In the present work, instead of the phaseshifter, variable cable delay was applied. The direction of rotating magnetic field is defined by the directionof the static magnetic field (H0) as shown in Ref. [1]. If NMR asymmetry disappears by applying rightcircularly RF field, the sign of μ is positive [3]. In the present work, the polarized 29P was produced by using
a 12 MeV polarized proton beam and a 0.5 mm thick Si target (p-High) [4, 5]. We applied H0=1.647 kG. In
this case, Larmor frequency of μ for 29P is about 3.1 MHz, corresponding to about 320 ns revolution time.
In the rotating magnetic field system, we fixed the
two RF fields to 3.10±0.05 MHz. and measured the
NMR asymmetry by changing the cable delay.
Observed cable delay dependence of the NMR
Asymmetry (%)

asymmetry is shown in Fig. 1. Experimental NMR
asymmetry disappears at around 50 ns delay. In theoffline measurement, by using pick-up coils, we
confirmed that when 80 ns delay is applied, rightcircularly RF field is produced. Although there isslight difference of the delay between online andoffline results, the present results show that thesign of μ for 29P is positive. The positive sign isconsistent with prediction by the Schmidt value

Cable delay (ns)(μ=+2.7926 n.m.) for the nucleus (odd Z, l=0).
Fig. 1. Observed cable delay dependence of NMR
asymmetry. Grey region shows the NMR asymmetry
without RF field.

In further studies, we will apply the present
system to determination of the sign of μ for the
nuclei, for which only absolute values are known.
References[1] D. Nagae et al., UTTAC Annual Report 2013, UTTAC-83 (2014) 12.
[2] N. J. Stone, At. Data Nucl. Data Tables 90 (2005) 75.
[3] D. Nagae et al., UTTAC Annual Report 2012, UTTAC-82 (2013) 7.
[4] A. Ozawa et al., UTTAC Annual Report 2018, UTTAC-88 (2019) 7.
[5] A. Ozawa et al., UTTAC Annual Report 2019, UTTAC-89 (2020) 7.

7

A study of 𝒑⃗ + nat.Si reaction by the 6 MV tandem accelerator

2.2

A. Yano, A. Ozawa, T. Moriguchi, Y. Yamato, K. Tomita, N. Kaname, M. Hayashi
It is important to measure nuclear magnetic moments (μ) since they reflect the nuclear shell structure.
In particular, if μ in the pair of mirror nuclei are measured, we can calculate their expectation values ofangular momentums. Our group has been measuring μ of 30P, which is self-mirror nucleus (N=Z), by using
the nuclear magnetic resonance method observing β-ray emission asymmetry (β-NMR). In this FY, tooptimize experimental conditions of β-NMR, we measured the energy and target dependences of yield and
β-NMR effect for 29P. Since the proton number of 29P is the same as that of 30P, hyperfine interaction of 29P
with target is equal to that of 30P.
Experimental setup is similar to that ofthe previous β-NMR measurement [1]. In
order to confirm the production of 29P, we
irradiated a 0.5 mm thick wafer of Si with a
12 MeV polarized proton beam. Figure 1
shows the typical time spectrum of counted
β-ray. Solid lines indicate fitting results
taking into account the life times of 29P, 30P,
and25

Al. These results imply that the

production of 29P is confirmed in this study.
By integrating the spectra for the nuclei, we
deduced the yields of the nuclei.

Fig. 1. Typical time spectrum of the observed β-ray.

The beam energy dependences of yields
for 29P and 30P via 𝑝⃗ + nat.Si reaction are
shown in Fig. 2. The yield of β-ray in Fig. 2
is normalized by the beam current. The yieldof 29P increases as the beam energy increases
from 6 to 12 MeV. This result suggests that
12 MeV polarized proton is suitable for the βNMR measurements for 30P.
As shown in Fig. 3, the energy
dependenceofasymmetry

which

is

proportional to a nuclear spin polarization is
not seen clearly. The statistical error around 6
and 8 MeV is due to the low beam intensity.
Consequently, we conclude that 12 MeV istheoptimumenergyforFig. 2. Yields of 29P and 30P as a function of polarized
proton energy.

β-NMR

30

measurement of P in terms of yield and β-

8

NMR effect.
To make a suitable choice of Si-containing
target, β-NMR effect measurements of 29P were
performed with Si, SiO2 and SiC. Thesematerials containstructures.

nat.

Si and are crystalline

Consideringadifferenceinsymmetry of crystal structure, we prepared two
kinds of SiO2 crystals. One has a Z-cut surface
which is expressed as (0 0 0 1) in Miller index,
meaning that its surface is perpendicular to Z
axis of the crystal structure. Another has an Xcut (2 −1 −1 0) surface perpendicular to X axis.

Fig. 3. Measured asymmetry of 29P β-NMR as afunction of the beam energy.

We observed large β-NMR effect of 29P only for
Si. In this viewpoint, using a Si target isappropriate for β-NMR measurements of 30P.

It is reported that β-NMR effect with a Si target is influenced by the electric field gradient in the latticeof Si crystal [2]. We need to consider this effect in future experiments.
References[1] A. Ozawa et al., UTTAC Annual Report 2017, UTTAC-87 (2018) 7.
[2] W. Seelinger et al., Nucl. Instr. Meth. Phys. Res. B 63 (1992) 173.

9

2.3

Production of high intensity spin polarized 19O for materials science
applications

M. Mihara1, Y. Otani1, Y. Kimura1, M. Fukuda1, K. Matsuta1, H. Ishiyama2, T. Moriguchi, K. Tomita,
A. Yano, A. Ozawa
Solid oxide fuel cells (SOFC) are attracting much attention as clean energy systems with potential togenerate a large amount of energy [1]. The 17O (I = 5/2) nuclear magnetic resonance (NMR) is an important
method for investigating the oxygen ion conductivity in SOFC materials [2]. However, the naturalabundance of the 17O isotope is only 0.038%, which becomes a bottleneck of 17O NMR studies, because
expensive samples enriched with 17O are required to detect NMR signals. In this situation, a short-lived
unstable nucleus 19O (T1/2 = 26.9 s, I = 5/2) is one of the alternative oxygen NMR probes to the stable 17O
nucleus. The β-ray detected NMR (β-NMR) technique using short-lived radioisotopes has been applied tovarious materials science studies. The β-NMR of 19O in the SOFC materials does not require enrichedsamples, which will significantly reduce the cost and process of preparing samples. Previously, spinpolarization of 19O in the low energy nuclear reaction 18O (d, p) 19O has been studied [3] and then, the nuclear
magnetic dipole (μ) and electric quadrupole (Q) moments have been precisely determined [4]. In the present
study, we have tried to produce spin polarized 19O via the inverse kinematics reaction d (18O, 19O) p, in order
to utilize 19O as an oxygen NMR probe nucleus for the study of SOFC materials.
The experiment was performed at the A7 course of the UTTAC facility. The experimental setup is shownin Fig. 1. A 30-MeV 18O4+ beam provided by the 6-MV tandem accelerator impinged on a deuterium
absorbed Ti (TiDx ; x ~ 1) foil with a thickness of 1 μm. The 19O nuclei were produced through the d (18O,
19

O) p reaction and implanted into a catcher sample CaO or TiO2. The emerging angle of 19O was selected

to be about 5° where the maximum spin polarization of about 3% is expected from the previous study on
the 18O (d, p) 19O reaction [3]. The sample within a cylindrical vacuum chamber was placed inside a Halbach
array permanent magnet (SuperMagnetMan HB0080) which generates a magnetic field B ~ 0.5 T. The
Halbach magnet has a doughnut
RF coilshape with the outer and innerdiameters of 84 mm and 40 mm,
respectively, and the thickness of

18O

30 MeVθ

TiDxcollimator
19O(x = ~1)

25 mm. The spot size of thecollimated 19O ions was about

Plastic scintillating fiber

4×10 mm2 at the sample position

B = 0.5 T

where the field inhomogeneity

Halbach array
permanent magnet

became a few %. A radio
frequency (rf) coil was also set

Fig. 1. Experimental setup.

in the vacuum chamber to induce
1
2

CaO
or TiO2

Department of Physics, Osaka University
RIKEN Nishina Center for Accelerator-Based Science

10

NMR. Two sets of β-ray counter telescopes were1000

placed between the chamber and the inner space ofa plastic scintillation fiber (Kuraray SCSF781.00mm-D) array, which was optically connected to

Coutnts

the magnet. Each telescope consists of two layers of

100
10

a 16 ch multi pixel photon counter (MPPC) array
1(Hamamatsu C13368-3050EA-16) through optical0fiber.
Figure 2 shows a typical β-ray time spectrum
after irradiation of the 18O4+ beam with an intensityof 400 nA. The spectrum is well explained by thehalflife of 19O with T1/2 = 26.9 s [5]. The β-NMR

50

100

150
t (s)

200

250

Fig. 2. β-ray time spectrum from a catcher material
after irradiation of a 30-MeV 18O beam on a TiDx
target.

measurement was performed by applying an rf field with the frequencies at around 2.4 MHz, the Larmor
frequency at B = 0.52 T which is the calibrated value at the center of the magnet. However, no significant
resonance was observed. Although the reason is not clear, the following two points should be considered.
One is the misalignment of the sample along the beam axis, which might have caused mismatch of the NMR
condition. The other is the capture of unpolarized electron(s) in the target, which reduces nuclear spinpolarization during flight due to the hyperfine interaction. We are planning further measurements after
improvement of the setup by adding a guiding field and a tilted foil stack to maintain and enhance 19O
nuclear polarization.
References[1] H. Iwai et al., Transactions of the JSME 111 (2008) 13.
[2] T. Viefhaus et al., Solid State Ionics 177 (2006) 3063.
[3] K. Matsuta, et al., Nucl. Instr. Meth. Phys. Res. A 402 (1998) 229.
[4] T. Minamisono et al., Phys. Lett. B 457 (1999) 9.
[5] "Table of Isotopes CD ROM Edition" Edt. R. B. Firestone and V. S. Shirly, Wiley-Interscience (1996).

11

2.4

Performance test of low-pressure MWDC with 1/3-cell staggered
layersS. Y. Matsumoto1,2 , A. Sakaue3 , K. Itahashi2 , T. Moriguchi, T. Nishi2 , R. Sekiya1,2 , R. Tsuji1 , T. Uesaka3
K. Yako2 , J. Zenihiro1
In December 2020, we conducted a performance test of a new low-pressure multi-wire drift chamber(MWDC) using proton beams to evaluate tracking resolution, efficiency and the stability under a high-rate
beam condition.
The MWDC has been developed mainly for two experiments at RIBF, RIKEN, search for double(( ))Gamow-Teller giant resonance (DGTGR) via 12 C, 12 Be 0+
reaction [1] and systematic high-precision2( 3 )spectroscopy of pionic atoms (piAF) via d, He reaction [2]. In these experiments, the MWDC (i) shouldhave high position resolution with good tracking efficiency for the precise spectroscopy, and (ii) should
work under high rate background condition (an order of MHz triton in the DGTGR experiment and protonin the piAF experiment).
For these purposes, we developed new MWDCs with two features, namely low gas-pressure operation in the vacuum and novel plane configuration. The former feature is important in terms of suppression of the multiple scattering of the incident particles in the detector materials [3] and the latter
contributes to achieve homogeneity of the spectral resolution by the 1/3-cell staggered three-layer structures (XX’X”(0◦ ), UU’U”(+30◦ ), VV’V”(−30◦ )). A typical MWDC is known to exhibit a non-negligible
inhomogeneity in the spectra originating from an analytic bias in the proximity of wires [4, 5]. For each
set of layers in the new MWDCs, we use two of the three layers by neglecting the one where the trajectory
is closest to a wire.

Fig. 1. Detector setup on the A7 beam line in UTTAC.

We performed the test experiment in 2.0 days at the A7 course in UTTAC, by using primary proton
beams of 12 MeV/u. The beam was detected and identified by a plastic scintillator at the downstream of
1 Department of Physics, Kyoto University
2 RIKEN
3 Center for Nuclear Study, University of Tokyo12

the MWDCs as shown in Fig. 1. MWDC was operated with pure isobutane gas at 10 – 30 kPa.
The stability test of the MWDCs was conducted with around 10 kHz proton beams. This condition iscomparable with the expected background in terms of the space charge effect. Under this severe condition,
we verified that the detection efficiency does not change by more than a few percent.
From the above results, we found that the new MWDCs show satisfactory performance for our experiments.

References[1] T. Uesaka et al., RIBF Proposal, No.141 (2015).
[2] K. Itahashi et al., RIBF Proposal, No.135 (2015).
[3] H. Miya et al., Nucl. Instr. Meth. Phys. Res. B 317 (2013) 701.
[4] T. Nishi et al., Phys. Rev. Lett. 120 (2013) 152505.
[5] Y. K. Tanaka, Ph. D. thesis, Univ. Tokyo (2016), Appendix B.

13

2.5

Measurement of convoy electron yield for atomic ionsS. Tomita, R. Suganuma, G. Kawasaki, S. Hatada
The main mechanism of radiation effects by fast charged particles is the energy transfer through theionization of target materials, which leads to temperature increase along the trajectory of the incident
particles. There is also a radiation effect through the chemical reaction caused by radicals which areproduced by ionization of target materials and also by thermalized electrons. The radicals could play anessential role in the radiation effect, especially on a biological target, since Boudaı̈ ffa et al. [1] reported
experimental results that show the resonant formation of the DNA strand break below 20 eV. Therefore, theenergy distribution of low-energy scattered electrons could be crucial to understand the biological radiation
effects. In the target material, such scattered electrons interact with the projectile ion [2-4]. Thus the energy
distribution of scattered electrons is affected by the projectile ions. Such an effect would be most significant
for the convoy electrons that are a part of secondary electrons emitted towards zero degrees with the same
velocity as the projectile ions. To investigate the interactions of electrons with projectiles inside the target
material, we plan to measure convoy electron yield for various ion beams. For this purpose, we havedeveloped a zero-degree electron spectroscopy apparatus at a beamline of 1 MV Tandetron accelerator at
UTTAC.
The schematic diagram of the experimental setup is shown in Fig. 1. An electrostatic energy analyzer
located downstream of the thin target foil determines the kinetic energy of the electrons emitted towards
zero degrees. Since the trajectories of analyzed electrons are affected by geomagnetism, we have built triaxial square Helmholtz coils to generate a uniform magnetic field. A typical energy spectrum of secondary
electrons is shown in Fig. 2. The apparent peak of convoy electron is observed at 160 eV which is equal to
the kinetic energy of electron with the same velocity as the projectile ion of 0.29 MeV H+. In Fig. 3, theelectron yield at the peak position is shown in a two-dimensional plot as a function of the electric current
on the square Helmholtz coil in the X (horizontal) and y (vertical) directions. The magnetic field at the
maximum value of the convoy electron yields corresponds to the spatial position where geomagnetism iseliminated with the tri-axial square Helmholtz coil. We plan to measure convoy electron yields with thisapparatus for various ion beams, including cluster ion beams.

Energy analyzer(ΔE/E = 3.3%)
Targete-e-

Faraday cup

Fig. 1. Schematic diagram of the experimental setup.

14

Fig. 2. Typical energy spectrum of convoy electrons from thin carbon foil of 4.9
μg/cm2 for an incident beam of 0.29 MeV H+.

Yield (arb. unit)

Iy (A)

2.0

9.0

1.5

8.0

1.0

7.0

0.5

6.0

0.0

5.0

-0.5

4.0

-1.0

3.0

-1.5

2.0

-2.0

1.0

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

Ix (A)

Fig. 3. The 2-dimensional plot of the yield of convoy electrons as a function ofelectric currents of horizontal ( I x ) and vertical ( I y ) magnet coils.

References[1] B. Boudaı̈ ffa et al., Science 287 (2000) 1658.
[2] Y. Shiina et al., Nucl. Instr. Meth. Phys. Res. B 460 (2019) 30.
[3] S. Tomita et al., Nucl. Instr. Meth. Phys. Res. B 354 (2015) 109.
[4] S. Tomita et al., Phys. Rev. A 73 (2006) 060901.

15

3.
ACCELERATOR MASS SPECTROMETRY

Negative ion source for AMS

3.1

Performance report of the Tsukuba 6 MV multi-nuclide AMS system infiscal 2020

K. Sasa, T. Takahashi, M. Matsumura
The Tsukuba 6 MV multi-nuclide AMS system was operated for a total of 39 days and 400.4 hours infiscal 2020. We measured 406 samples in total dealing with rare radionuclides such as 36Cl and 129I shownin Table 1. Figure 1 shows monthly-measured rare nuclides from April 2020 to March 2021.
Table 1. Number of measured 36Cl and 129I samples in fiscal 2020.

Item
Cl-36
I-129
Sub total

Reagent & blanksamples
971
80Standard samples

Unknown samples

7
53
60

13
253
266

Total
29
377
406

Fig. 1. Monthly-measured nuclides by the multi-nuclide AMS system from April 2020 to March 2021.

36

Cl-AMSIn fiscal 2020, 36Cl analysis was applied for tracing cosmic ray events remaining in the ice-core. The

DF2 ice-core samples were obtained from the DF station (77°19’S, 39°42’E, 3810 m above sea level) at
Antarctica in 2007 [1]. The depth of interest was 239.5–242.0 m, corresponding to an age of 5494 BCE (+11y/−15 y) to 5407 BCE (+11 y/−18 y) for the 5480 BCE cosmic ray event [2]. The ice-core was cut into 2.5cm lengths. The average weight of each sample was 27 g. We merged five chlorine-fraction samples in orderto resolve the 36Cl analysis to 4–5 years, and spiked 2 mg of Cl carrier (NaCl supplied by Fisher Scientific,USA) for each sample. The chlorine fraction (cation-exchange eluate) was converted to AgCl for 36Cl
analysis. After the sulfur reduction, the dried AgCl was pressed into a copper cathode with an AgBr backing
prepared under acid-aged conditions [3]. We measured 36Cl/Cl background and ice-core samples with a total

16

of 13 unknown samples under a beam condition of 36Cl8+ with 54.0 MeV (using a carbon foil stripper). The
background ratios of 36Cl/Cl ~ 3 × 10−15 were achieved with AgCl blank samples for 36Cl AMS. The average
concentration of ice-core samples was (0.97 ± 1.4) × 104 (atoms/g). As the result, there is no increase of 36Cl
concentrations in peak amplitude around the age of 5460 BCE.
129

I-AMS
The negative iodine ions (I−) were extracted from an AgI sample and accelerated to 5 MeV in the firststage of the tandem accelerator and exchanged to the positive ions (I5+) in an Ar gas cell for 129I-AMS. After
further acceleration to 30 MeV, 129I5+ was separated by high-resolution electric and magnetic analyzers
before detection of the ion with a gas ionization detector. We used S-Purdue (Z94-0597) and S-Purdue2(Z94-0596) reference materials (129I/127I ratios of 8.38 × 10−12 and 6.54 × 10−11) [4] as standards fornormalization at UTTAC. The background ratios as low as 129I/127I ~ 2 × 10−14 were achieved constantlywith AgI chemical blank samples in fiscal 2020.
129

I was mainly measured at the AMS system in order to investigate the radioactive contamination insurface soils, water samples, and dissolved matters in river at Fukushima, and to trace the oceanic circulation
with a total of 377 samples in fiscal 2020.
Reference[1] H. Motoyama et al., Scientific Drilling 5 (2007) 41.
[2] F. Miyake et al., PNAS 114(5) (2017) 881.
[3] S. Hosoya et al., Nucl. Instr. Meth. Phys. Res. B 438 (2018) 131.
[4] P. Sharma et al., Nucl. Instr. Meth. Phys. Res. B 123 (1997) 347.

17

3.2

Measurements of 129I in the Cooling Pond, Chernobyl

K. Nishizuka, A. Sakaguchi, V. Kanivetz1, K. Sasa, T. Takahashi, M. Matsumura, S. Yamasaki, K. Sueki
An estimated amount of radionuclides in excess of 2000 TBq was accumulated in the Cooling Pond
(CP) of the Chernobyl Nuclear Power Plant as a result of the nuclear accident [1]. The source of water forthis pond is the Pripyat River, which runs just east of the CP and is geographically lower than the CP. Even
after the reactors were closed, the water level in the pond was maintained by continuous pumping of waterfrom the river so as to prevent environmental releases/dispersion of radionuclides due to the lowering of thewater level in the cooling pond. However, the water level of the pond has been decreasing since 2014 as aresult of the cessation of pumping caused by the deterioration of the political situation and of thewarming/drying of the climate. In this study, we focused on the measurement of 129I amount in the pond,
which has not yet been evaluated. We also studied methods to accurately and precisely measure the total
iodine concentrations in environmental water samples.
Water samples were collected in 2018-2020 at the sites
N, NW, W, SW and S in the CP at some depths (Fig. 1). The
collected water and pore water samples from the sediments
were filtered through a 0.45 μm pore size filter, and a few
grams

of

each

samplewas

sub-sampled

for

ion

chromatography to determine the levels of dissolved major
cations and anions. Dissolved 137Cs was quantified with a Ge
semiconductor detector, and 90Sr was chemically separated
and its progeny 90Y was quantified with a liquid scintillation
counter. For the measurement of inorganic 129I, target
samples were prepared as AgI precipitates after purificationof the iodine using an appropriate amount of sample water.
The 129I/127I atom ratios in the samples were measured by the
AMS system at UTTAC, and the 127I concentrations were
measured by ICP-MS (Agilent 8800) using 185Re as aninternal standard. As a preliminary experiment for thedetermination of ‘total iodine’ in natural water samples,Fig. 1. Sampling locations

including inorganic iodine and organic iodine, we determined recovery rates of I-, IO3- and organic-I (γglobulin) in trap-solutions obtained from the pyrohydrolysis method. In these experiments, a standard IO3solution was prepared from the I− standard solution, using radioactive iodine 125I as a tracer.
The 129I/127I ratios were obtained in the range of (1−5)×10−7. These values are two orders of magnitude
higher than that of general environmental water (10−9). The depth distribution of 129I concentration in thewater column became higher at deeper layers of the pond (Fig. 2). In fact, 129I concentrations in the pore1

Ukrainian Hydrometeorological Institute18

water of the bottom sediments were one order of magnitude higher than those in the pond water, indicatingthat radioactive iodine may be being supplied to the pond water from the sediments.
The pyrohydrolysis method was applied to three iodine species, i.e., I−, IO3−, and organic-I, to investigate
a suitable method for total iodine determination, and their recoveries were 87.2±7.0, 82.8±4 and 135±14.3%,
respectively. Considering the composition of iodine species in environmental water, the recoveries andvariations obtained in this study are unacceptable. Further studies are needed to find an appropriate method
for bulk iodine measurements. We must also synthesize the organic iodine using 125I as a tracer since there
is no organic iodine standard that satisfies the accuracy of iodine concentration measurements by ICP-MS,
whereby it is possible to confirm the recovery rates of organic iodine in water samples.

Point : N
Depth : 9.7 m
Fig. 2. Depth profile of 129I (atoms/L) at point N

Reference[1] IAEA-TECDOC-1886, IAEA Vienna (2019) P28.

19

3.3

Surface distribution of iodine-129 in the Okhotsk Sea

T. Matsunaka1, S. Nagao1, M. Inoue1, Y. Taniuchi2, H. Kasai2, T. Takahashi, M. Matsumura, K. Sueki,
K. Sasa
The investigation of water dynamics change in the East Asian marginal seas such as the Sea of Japanand Okhotsk Sea caused by the recent global warming is essential for forecasting the response of ocean
circulation with climate change. Anthropogenic 129I (T1/2 = 15.7 million years) produced from the thermal
neutron fission, is dominated by release from nuclear fuel reprocessing plants in the Europe and supplied at
the Okhotsk Sea via atmospheric deposition and surface runoff. To illuminate the availability of 129I as a
tracer of surface circulation in the Okhotsk Sea, we investigated the horizontal distribution of 129I in 2018.
The dissolved 129I in surface water in the Okhotsk Sea varied from 15.0±0.7 to 26.6±0.8 nBq L–1, andwas negatively correlated with water temperature (Fig. 1B, R2 = 0.67) and salinity (Fig. 1C, R2 = 0.68). Thiswater temperature and salinity-dependent distributions revealed that the dissolved 129I in the area wascontrolled by mixing of water mass from the Okhotsk Sea surface seawater with cold and lower salinity andthe Soya warm current from the Sea of Japan with warm and higher salinity. 129I is considered to be a tracer
for the front of the Okhotsk Sea surface water.

B

A

C

Fig. 1. Surface distribution of 129I in the southern Okhotsk Sea in 2018 (A). The correlations between
129
I activities in surface seawater and water temperature (B) and salinity (C). The linear regression lines
and coefficients of determination (R2) are shown in the correlation diagrams.

1 Kanazawa University
2 Japan Fisheries Research and Education Agency

20

3.4

The Performance of Iodine-129 AMS measurements at the University ofTsukuba (FY 2020)

M. Matsumura, K. Sasa, T. Takahashi, A. Sakaguchi, T. Matsunaka 1, K. Sueki
Continuing from 2017, we have reported that the performance of 129I measurement by accelerator mass
spectrometry (AMS) for the development of the standard reference materials (STD) of 129I in the near future.
Details of the 129I AMS measurements are described in the references [1-3].
From April 2020 to March 2021, we measured 257 samples of 129I, the details of which are shown in
Fig. 1. The test samples were chosen from natural environment such as sea, rain, river water, and soil. Figure
2 shows the measured values of carrier-reagent blanks. The machine background is estimated to be on theorder of 10−15 in the 129I/127I ratio, which is sufficiently lower than the background level of the ratio of 2 ×
10−14 for ”Old Iodine” provided from Deep Water company, USA. However, sometimes, the measured
I/ I values in blanks ranged over ten times higher than 2 × 10−14. One of the causes for this might be the129 127

memory effect. The rise in blank values in 2018 and 2019 is most likely caused by this memory effect,
however, the memory effect has been prevented by measurement schemes since 2020.

Fig. 1. Details of measured 129I
by the AMS system in fiscal 2020.

Fig. 2. 129I/127I ratios in blanks.

In FY 2020, we have measured the certified materials. The results of measurement for Standard
Reference Material 3230, Level Ⅰ and Level Ⅱ, provided from the National Institute of Standards andTechnology (NIST, USA) are shown in Fig. 3. They were normalized by using Purdue-2 STD (Z94-0596)
with an 129I/127I ratio of 6.54 × 10−11 [4] (the value was revised in 2014 [5]), which was provided by the
Purdue Rare Isotope Measurement Laboratory (PRIME Lab) at Purdue University, USA. The nominal
I/ I ratios are (4.920 ± 0.062) × 10−10 and (0.985 ± 0.012) × 10−12, for NIST 3230- Level Ⅰ and Level Ⅱ,

129 127

respectively. The two samples after sputter-cleaning for 1 or 5 min. were measured in each run. The measured
values of Level Ⅰ are 10% lower than the nominal one. The resulting ratio and standard deviation (1σ) of the

precision are (4.361 ± 0.058) × 10−10 (1.3%) and (0.909 ± 0.065) × 10−12 (7.1%), respectively.
This work was supported in part by JSPS KAKENHI Grant Number 20H01173.
1

Kanazawa University

21

Fig. 3. Measured 129I/127I ratios of NIST 3230-STD. The error bars attached tomeasured points represent counting statistics.

References[1] K. Sasa et al., Nucl. Instr. Meth. Phys. Res. B 437 (2018) 98.
[2] M. Matsumura et al., UTTAC Annual Report 2019, UTTAC-89 (2020) 16.
[3] K. Sasa et al., UTTAC Annual Report 2020, UTTAC-90 (2021) 16.
[4] P. Sharma et al., Nucl. Instｒ. Meth. Phys. Res. B 123 (1997) 347.
[5] M. Caffee, (Purdue University), Private communication (2014).

22

3.5

Assessing of iodine-129 in the chemical sample preparation rooms forAMS

M. Matsumura, K. Sasa, T. Takahashi, A. Sakaguchi, T. Matsunaka1, K. Sueki
The workspace used to prepare samples for accelerator mass spectrometry (AMS) tends to become
gradually contaminated through the chemical treatment of samples with high 129I concentrations. Suchcontamination may lead to overestimated 129I in AMS analyses. Thus, we have continued assessing of 129I
in the chemical sample preparation rooms for AMS. From 2013 to 2014, environmental 129I from atmosphere

From 2017 to 2021, we measured

129

I fromatmosphere annually in the rooms C108, C209, andC304 at UTTAC, and also in the Non-RI, RI, and ICPMS rooms at CRiED. The experimental procedure wassimilar to the previous case [1, 2], except that we used a
Deep Water company, USA, with an 129I/127I ratio of 2 ×

for the ICP-MS room during November-December
2019. Furthermore, the129

I contamination rates strongly

previous values except for the C209-room in March
2019 [1, 2].
This work was supported in part by JSPS
KAKENHI Grant Numbers 20H01173.
References[1] M. Matsumura et al., UTTAC Annual Report 2014,
UTTAC-84 (2015) 20.
[2] M. Matsumura et al., Anal. Sci. 36 (2020) 631.

Non-RI room

104

C108
C209

RI room

10-1

C108
C304
C209

Non-RI
room

10-2
10-5
10-6
10-7
10-8
10-9

ICP-MS room
RI room
Non-RI
room

Back
ground

C304
C209
C108

2017
2019
2019
2021
4/3-4/25 3/11-4/1 11/20-12/11 1/5-1/26

Sampling period
Fig. 1. Variation of the measured 129I and 127I
contamination rates and 129I/127I ratio fromatmosphere.

DOI: 10.2116/analsci.20SBN05

1

I/

I/ I ratio are almost the same as or less than the

129 127

129 127

I ratio in the iodine trap solution

depend on the sample-preparation history of the rooms.
The levels of 127I and 129I contamination rates and the

C304

105

ICP-MS room

I (ng cm-2 day-1)

atmosphere are rather constant in all the rooms, except

RI room

127

rates of less than 1 [ng (nanogram) cm−2 day−1] from the

ICP-MS room
Background1031different carrier reagent ”Old Iodine” provided from
10−14. As seen in Fig. 1, the stable (127I) contamination

106

129

Dynamics, University of Tsukuba) [1, 2].

I (atoms cm-2 day-1)

was continuously monitored in the sample preparation rooms in the buildings of UTTAC and CRiED (the107Center for Research in Isotopes and Environmental

Kanazawa University

23

3.6

Depth profiles of 129I in soil derived from the Fukushima Dai-ichi Nuclear
Power Plant

Y. Gao, A. Sakaguchi, K. Sasa, M. Matsumura, T. Takahashi, H. Yokoyama, Y. Ota, K. Sueki
A large amount of anthropogenic 129I (T1/2 = 1.57×107 year) was released into the environment due tothe Fukushima Dai-ichi Nuclear Power Plant (FDNPP) disaster in March 2011. The anthropogenic 129I of
relatively single source and a short mixing time is one of the useful radioisotopes for the environmental
assessment around nuclear fuel reprocessing plants. Therefore, it is important to investigate the depth
distribution of radioactive 129I in the environment near the FDNPP area.
In the 129I studies related to the FDNPP accident, the workers have reported 129I depth profiles at uplandfield, empty lot, and ground level in Fukushima [1]. However, their observations of change in the depth
distribution have been limited to one sampling point for less than a year [2]. A long-term change of the 129I
distribution at a fixed point in the surrounding area of FDNPP remains unclear. In the present study, weinvestigate such relatively long-term migration behavior of 129I.
To estimate the mobility of trace long-lived radionuclide 129I in soil originating from the FDNPP accident,
it is necessary to compare the depth profiles for different years. We have collected 30-cm-long soil cores atNamie-machi, Fukushima on June 12, 2013, and September 10, 2017 [3]. Before use for AMS, it was
vacuum-freeze-dried and grinded using a mortar and pestle [3].
For the homogenized soil of 0.5 g, iodine was extracted by pyrohydrolysis with 0.5 g V2O5 [4]. Iodine
thus obtained was purified by solvent extraction and then it was precipitated as AgI. The isotope ratio 129I/127I
was measured by the AMS system at UTTAC. The 127I concentration in the trap solvent obtained bypyrohydrolysis was measured with the inductively coupled plasma-mass spectrometer (ICP-MS, Agilent
8800). The deposition amounts of 129I in the soil cores were calculated using 127I concentration obtained from
ICP-MS and 129I/127I ratio obtained from AMS.
Figure 1 shows the depth profiles of 129I deposition amount in soil cores collected from Namie-machi,
Fukushima on June 12, 2013, and September 10, 2017. In 2017. The deposition amount of the 0−9 cm(corresponding to 0 to ~70 kgm−2 mass depth) soil cores decreases sharply with increasing depth, while thedeposition amount of 9−30 cm does not depend on depth. These characteristics are basically consistent withthe results of soil core measurement in 2013. However, the accumulation at 0−30 cm is generally lower thanthat of 2013 soil core.
The background level for the deposition amount of 2013 soil cores at a depth of 9−30 cm is about 4.95
×10−4 mBq m-2, while that for 2017 soil cores at a depth of 9−30 cm is about 2.31×10−4 mBq m-2, as areshown by the vertical lines in Fig. 1. Even considering this difference in the background, the deposition
amount of 129I in the 0−30 cm surface soil shows an overall decreasing trend after 4 years. The different
backgrounds may be due to the distance of tens of meters between the locations where the samples werecollected.
Fig. 2 shows the fractions of the cumulative inventory above a certain depth to the total inventory as
plotted for 129I of 2013 and 2017 soil cores. In 2013, 82.9% of the FDNPP-derived 129I was present with the24top 22.7 kg m−2, 98.2% of the FDNPP-derived 129I was present with the top 49.5 kg m-2. In 2017, 82.1% of
the FDNPP-derived 129I was present with the top 27.05 kg m−2, 98.3% of the FDNPP-derived 129I was present
with the top 49.6 kg m−2. This indicates that the FDNPP-derived radioiodine remains in the same penetration
depth between 2013 and 2017.

Fig. 1. Mass depth distributions of 129I deposition amount in soil cores collected from Namie-machi,
Fukushima on June 12, 2013, and September 10, 2017. Estimated background values are shown by thevertical dotted lines.

Fig. 2. The fractions of the cumulative inventory for the FDNPP 129I after subtracting the 129I background.

References[1] M. Honda et al., Applied Geochem. 85 (2017) 169.
[2] M. Honda et al., J. Environ. Radioact. 146 (2015) 35.
[3] Y. Ota et al., UTTAC Annual Report 2018, UTTAC-88 (2019) 21.
[4] Y. Muramatsu et al., Quat. Geochronol. 3 (2008) 291.

25

4.
ION-BEAM APPLICATIONS

RF ion source providing a He micro-beam

4.1

In-operand lithium depth profiling by use of NRA

Y. Sugisawa, S. Kobayashi1, N. Kishi, R. Shimizu1, 2, T. Hitosugi1, D. Sekiba
All-solid-state Li-ion batteries are expected as those in the next generation, which can be applied tovarious industrial products. Several solid electrolytes with high performance have been reported [1].
However, they still have some problems to be solved for practical applications [2]. In-situ observation of
Li-ion migration during the battery operation is required to solve such problems. Nuclear reaction analysis(NRA) using 7Li(p, α)4He is one of the direct methods for quantitative depth profiling of lithium and/or Liion in solid materials [3, 4]. This technique can also reduce the radiation damage of samples due to the lower
energy deposition of a beam of protons than that of relatively heavier ions used for elastic recoil detection
analysis (ERDA). These features of NRA are suitable for operand Li depth profiling over the whole battery
stack in a single measurement. In our present study, we observed a test stack similar to the practical one
under the charging and discharging conditions. We confirmed that our NRA system can visualize thetransportation of Li in the sample. Furthermore, we determined(a)the upper limit of the beam current, which does not induce
dielectric breakdown of the solid electrolyte.
NRA and Rutherford backscattering spectrometry (RBS)
were performed using 1 MV Tandetron at UTTAC. In theexperiment, a 1.5 MeV 1H+ ion beam was incident on the sample
at an angle of θp = 40o with respect to the surface normal, as shownin Fig. 1(a). The emitted α particles and backscattered H ions(b)were detected by a solid-state detector at an angle of θe = 150o.
The beam size of 1 × 1 mm2 was shaped with a slit system. Figure1(b) shows the schematic of the sample. The sample consists of a
stacked layer of Li (1 μm)/Li3PO4 (1 μm)/Au (100 nm) deposited
on a Si3N4 substrate of 100 nm thickness. The incident beam
enters the backside of the sample to observe the Au/Li3PO4 (solid
electrolyte) interface with a better depth resolution. Since
dielectric breakdown of the electrolyte occurred for the beam

Fig. 1. Schematics of (a) the experimental arrangement and (b) the sample.

current greater than 50 nA, we maintained the beam current less than 30 nA during the measurements. In
this study, three measurements were performed: after charging, discharging, and recharging in the sample
by changing the potential of the Au layer relative to the Li layer. We applied the potential voltage of +5 V
for charging and to +0.1 V for discharging. The voltage was held during each measurement. It is expectedthat some fraction of Li is transported from the Li (negative electrode) layer to the Au layer in the discharging
process, and reverse transportation occurs in the charging process. In addition, we note that an unexpected
formation of Au-Li alloy in the Au layer is observed in the discharging process.
1
2

Tokyo Inst. Tech.
JST PRESTO

26

Figure 2 shows the energy spectra of RBS and NRA. Because of the high energy (~8 MeV) of the α
particles emitted in the 7Li(p, α)4He reaction, we can observe both the RBS and NRA spectra separately.
The spectra obtained under the charging with +5 V (1), discharging with +0.1 V, and recharging with +5 V
(2) conditions are shown by the blue, red, and green lines, respectively. The inset of Fig. 2 shows the NRA
spectra which consist of three energy ranges corresponding to the Li, Li3PO4, and Au layers, as indicated by
the broken lines. Comparison of the NRA spectra obtained at +5 V (1) and +0.1 V signifies the Litransportation from the Li layer to the Au layer. Subsequently, the Li concentrations in the Li layer and AuLi layer are not fully recovered even under the condition at +5 V (2) for the recharging process. This result
implies that significant amounts of Li ions diffuse into the Au layer and remain stable, thereby forming the
Au-Li alloy.
In the RBS spectra, the assignment of each feature or contour to each element is given in Fig. 2. The
spectra essentially unchanged during the charging/discharging process, except that the Au peak became
wider and lower after discharging. This change also supports the stable formation of Au-Li alloy, as
mentioned above. The amounts of charge transfer through the sample during discharging and recharging
was 28.8 and −17.3 mC, respectively. This reduction of charge transfer agrees with the result of NRA andRBS qualitatively. The difference might be interpreted in terms of the remaining Li ion in the Au layer.
In conclusion, we confirmed that the NRA system allows measurements under operation of the all-solidstates Li-ion battery and visualize the Li transportation during the charging/discharging process. In near
future, we investigate the cross-section of 7Li(p, α)4He reaction in detail by ourselves. Then we will makequantitative discussion on the results obtained in the present work.

Fig. 2.

RBS and NRA spectra measured for the Li/Li3PO4/Au stack fabricated on a thin Si3N4 substrate.

References[1] Y. Sun et al., Chem. Mater. 29 (2017) 5858.
[2] T. Minato, T. Abe, Progress in Surface Science 92 (2017) 240.
[3] A. Sagara et al., Nucl. Instr. Meth. Phys. Res. B 34 (1988) 465.
[4] J. Raisanen, Nucl. Instr. Meth. Phys. Res. B 66 (1992) 107.

27

4.2

Scanning microbeam PIXE analysis of silica glass particles released fromthe FDNPP

K. Sueki, T. Nakamura, S. Ishii, K. Sasa, S. Tomita, M. Sataka, H. Naramoto, H. Kudo
Due to the Fukushima Daiichi Nuclear Power Station (FDNPS) accident in March 2011, a large amountof radioactive substances was released into the environment. Among the released substances, there areparticles of smaller than 1 mm diameter, called radioactive particles. It is known that radioactive particles
are glassy, insoluble in water, and contain radioactive cesium as a radiation source [1]. Radioactive particles
are roughly classified into two types, Type A and Type B, according to their size and the 134Cs/137Cs activity
ratios before nuclear decay, i.e., the corrected ratios back to March 11, 2011 [1]. Type A particles derived
from Units 2 or 3 of FDNPS are spherical with a diameter of about 1−10 µm, having very high specificactivity and the 134Cs/137Cs activity ratios of about 1.0−1.1. On the other hand, Type B particles derived from
Unit 1 are of an amorphous shape with a diameter of 10 µm−1 mm, having the 134Cs/137Cs activity ratios ofabout 0.93 and specific activity smaller than that of Type A particles. In previous studies, Cs L-X rays canbe observed in Type A particles by scanning electron microscope (SEM/EDS) analysis equipped with anenergy dispersive X-ray analyzer, and distribution information of Cs in the particles has been obtained. On
the other hand, Type B particles do not contain Cs with a sufficient concentration observable by SEM/EDS
analysis, hence detailed distribution information in the particles is hard to obtain.
PIXE is useful to measure heavy elements that cannot be observed by SEM/EDS. In a previous work,
heavy elements (Zn, Sr, Zr, Ba and Pb) in radioactive particles were observed by PIXE using 1MV Tandetron[2]. In the present study, in order to obtain information on the element distribution in Type B particles wehave applied particle induced X-ray emission method (PIXE) using the microbeam course of the 6 MV
tandem accelerator at the University of Tsukuba.
The samples were irradiated with a 4 MeV proton beam focused to a size of 3−4 µm square, and thegenerated characteristic X-rays were measured by a cadmium telluride (CdTe) detector. The CdTe detector
allowed to measure KX-rays of the elements of interest due to the relatively high detection efficiency of Xrays from 5 keV up to 100 keV, and to obtain information on the element distribution in the radioactive
particles. The standard glass (NIST SRM1412a) was irradiated with a 4 MeV proton microbeam focused toa size of 4 µm square, and the generated characteristic X-rays were used for the energy calibration and thesensitivity evaluation. The X-ray sensitivity was sufficient for Zn (3.10 wt%) and Sr (3.42 wt%), but wasalmost at the detection limit for Ba (0.102 wt%).
Figure 1 shows the results of PEXE spectra for the two radioactive particles (particles T47 and R008)
actually released in the FDNPS accident. In the spectra, we see Sr, Zr, Ba K-X rays and Pb L-X rays that
could not be detected by SEM / EDS analysis. However, it is found that the target Cs spectrum is below thedetection limit in terms of the detection efficiency of the CdTe detector. Figures 2 and 3 show elemental
mapping for particle T47 in the area of 400 µm square and for particle R008 in the area of 250 µm square,
respectively. Elemental mapping of Sr and Pb could be obtained for both particles, while for Ba the S/Nratio was too low to obtain elemental mapping. It is found from the mapping that the heavy elements of Sr

28

and Pb are relatively uniformly distributed in the particles.

T47
R008

Fig. 2. PIXE images of particle T47.

Fig. 1. PIXE spectra of radioactive particles.

Fig. 3. PIXE images of particle R008.

References[1] Y. Satou et al., Geochem. J. 52 (2018) 137.
[2] M. Kurosawa et al., UTTAC Annual Report 2018, UTTAC-88 (2019) 31.

29

4.3

Depth resolution of transmission ERDA with 8 MeV He for observation of
H in solids

H. Kudo, H. Naramoto, M. Sataka, S. Ishii, K. Sasa, S. Tomita
Refinement of elastic recoil detection analysis with transmission layout (T-ERDA) is required to obtain
detailed knowledge about the state or behavior of hydrogen in matter [1]. For this purpose, depth resolutionof hydrogen analysis by T-ERDA has been studied by an experimental approach extended from thepreviously reported work [2]. As a result, we have identified the main factor determining the depth resolutionof T-ERDA [3, 4].
In the present experiments, Al foils and PPS [polyphenylene sulfide (C6H4S)n] films were stacked andused for test samples. The thicknesses of the Al foils are 5, 10, 15, 20, 50, 65, 70, 75 and 80 μm, and the
PPS thickness is 1.35±0.05 μm, which is thin enough to use as an H marker. The sample names and structuresare summarized in Table 1. The experimental setup and procedure are similar to the previous case [1]. A Si
surface-barrier particle detector for energy analysis of H was set on the ion-beam axis and a sample wasplaced in front of the detector. The target-detector distance was 14 mm. The angular range of acceptance ofthe detector, being expressed as 0 to ϕm polar angle with respect to the beam axis, was adjusted by attachinga circular aperture in front of the detector. In the present experiments, we have chosen ϕm = 4.1° for narrowand 11.1° for wide tacceptance conditions, respectively. These are typical conditions chosen to obtainsufficient count rate of recoil H for a wide range of H concentration.
Table 1. Names and structures of samples for T-ERDA
Sample name
Structure
S-1
PPS on Al(50 μm)
S-2
Al(10 μm) on PPS on Al(50 μm)
S-3
Al(20 μm) on PPS on Al(50 μm)
S-4
PPS on Al(80 μm)
S-5
Al(5 μm) on PPS on Al(75 μm)
S-6Al(10 μm) on PPS on Al(70 μm)
S-7
Al(15 μm) on PPS on Al(65 μm)
Figure 1 shows energy spectra of H measured under the narrow acceptance conditions (ϕm = 4.1°) for S1 to S-3 samples. For convenience of analysis, the yields have been scaled to have the same peak height asof S-1. We see sharp peaks originating from H in the PPS film. The three peaks are slightly asymmetric,
which can be recognized by the larger number of plots (equally spaced with respect to H energy) on the left
side than on the right side, indicating the existence of low-energy tails. The peak energies can be accounted
for with the depth scales indicated in Fig. 1. For the three cases, however, we see slight shift of the peakenergy to the low-energy side from the scale. Such peak shift arises from the finite thickness of the PPS film.
Since for both the incident He and recoil H, the ratio of PPS to Al stopping power is 0.64, the effective
thickness of PPS measured on the Al depth scale is 1.35 × 0:64 = 0:86 μm. Accordingly, we may expect thepeak shift equal to the half thickness of 0.43 μm and thereby the observed peak shifts can be explained. In

30

Fig. 2, the dashed curve shows the calculated spectrum by TRIM code for 0-degree recoil of H starting fromthe surface of 50-μm thick Al. The peak energy of 4.31 MeV by TRIM coincides with the origin of the depth
scale. About 60% of the experimental FWHM value of 0.130 MeV corresponds to the TRIM value of 0.081
MeV which is due to energy straggling.
Figure 2 shows energy spectra of H measured under wide acceptance conditions (ϕm =11.1°) for S-4 toS-7 samples, in which H yields are shown for the same number of incident He. Low-energy tails are morediscernible than those in Fig. 1. We also see low-energy shift of the H peak from the depth scale, which isdue to the PPS thickness. In Fig. 2, the dashed curve shows the calculated spectrum by TRIM for 0-degree
recoil of H starting from the surface of 80-μm thick Al. Again, the peak energy of 3.77 MeV by TRIM
coincides with the origin of the depth scale.

Fig. 1. T-ERDA spectra of H measured for S-1 to S-3
samples with the narrow acceptance of ϕm = 4.1°.
The calculated spectrum using TRIM for 0-degree
recoil is also shown for comparison of the peak widths.

Fig. 2. T-ERDA spectra of H measured for S-4 to S-7
samples with the wide acceptance of ϕm = 11.1°. The
calculated spectrum using TRIM for 0-degree recoil
is also shown for comparison of the peak widths.

From the analysis of the experimental data, we have found that the main degrading factor for the depth
resolution is the energy straggling of H in Al for narrow acceptance conditions of the detector. As theacceptance angle of the detector increases, the low-energy side of recoil H spectrum extends to form a tail,while the sharp high-energy side remains unchanged. It follows that the depth resolution is degraded by theenhanced FWHM value of the deformed triangular spectrum as a result of the extended low-energy side.
However, the spectrum shape having a long tail cannot be fully characterized only by its FWHM value. The
contrast of 3D image like those reported previously [1] might be more suitably understood with the
sharpness of high-energy edge of the image rather than with the FWHM value. Thus, the depth resolution
should be properly defined, depending on the observed image of interest.
References[1] A. Yamazaki et al., AIP Advances 9 (2019) 105111.
[2] A. Yamazaki et al., UTTAC Annual Report 2019, UTTAC-89 (2020) 24.
[3] H. Kudo et al., arXiv:2103.13034 [physics.ins-det].
[4] H. Kudo et al., J. Phys.: Condens. Matter https://doi.org/10.1088/1361-648X/ac17ac

31

5.
ISOTOPE APPLICATIONS

6T superconducting magnet for Mössbauer Spectroscopy

5.1

Behaviors of vacancies in Mg-implanted GaN during ultra-high-pressure
annealing studied by a monoenergetic positron beam

A. Uedono, H. Sakurai1,2, T. Narita3, K. Sierakowski4, M. Bockowski1,4, J. Suda1, S. Ishibashi5, S. F.
Chichibu1,6, T. Kach1
The GaN-based vertical power devices require embedded p-type regions to suppress the electric field
spreading near the edges of junctions, which is effective for obtaining high breakdown voltages [1]. Ion
implantation is a common technique for selective p-type doping, but it is well known that the removal of
implantation induced defects is difficult compared with that for Si or SiC [2]. In the present study, we useda monoenergetic positron beam to study the annealing behaviors of vacancy-type defects in Mg-implanted
GaN with ultra-high-pressure annealing (UHPA) process [3].
Mg+ ions were implanted into the samples to obtain 300-nm-deep box profiles with Mg concentrations[Mg] of 1×1019 cm−3 at room temperature. The energies of Mg+ ions were 30, 70, 150, and 300 keV, and thecorresponding dosages were 2×1013, 5×1013, 1×1014, and 3×1014 cm−2, respectively. The samples wereannealed at temperatures between 1000°C and 1480°C (5 min) under a N2 pressure of 1 GPa using a highnitrogen-pressure solution system.
Figure 1 shows the values of S parameter of Mgimplanted GaN before and after UHPA as a function ofincident positron energy E. For the unimplanted sample,
the S value at E ≥ 20 keV is close to S for defect-free GaN.
For the as-implanted sample and ones annealed at 1000–
1200°C, the S values are larger than S for defect-free
GaN, which can be attributed to the trapping of positrons
by vacancy-type defects.
The solid curves in Fig. 1 are fits to the experimental
data. In the fitting, the region sampled by positrons was
divided into three or four blocks. Derived depth

Fig. 1. S parameter as function of incident
positron energy for Mg-implanted GaN before
and after UHPA.

distributions of S are shown in Fig. 2. Figure 3(a) and (b)shows the depth distributions of Mg and H measured by SIMS, respectively.
The incorporation of H can be attributed to unintentional moisture in the UHPA chamber. No differencein the Mg distributions for the as-implanted sample and the samples annealed at 1000‒1200°C is observed.
After annealing at 1300°C, Mg starts to diffuse toward the inside of the samples. The Mg distribution forthe sample annealed at 1400°C is identical to that for the sample annealed at 1480°C.
1

Nagoya University
ULVAC Inc. Kanagawa
3
Toyota Central R&D Labs., Inc.
4
Polish Academy of Sciences
5
National Institute of Advanced Industrial Science and Technology (AIST)
6
Tohoku University
232

Fig. 2. Depth distributions of S obtained fromanalysis of S−E curves in Fig. 1.
Fig. 3. Depth distributions of Mg and H for Mgimplanted GaN measured by SIMS.

In Fig. 2, for the as-implanted sample and the sample annealed at 1100°C, the position of the first andsecond blocks with a high S value (≤ 500 nm) agrees with the box profile of Mg. This can be attributed tothe high [Mg] in this region and a resultant high total deposited energy of Mg that was used to substituteatoms. A damaged region was introduced up to the depth of 900‒1300 nm, and this region is deeper thanthe block profile of Mg. This is due to the introduction of defects by Mg implanted below 300 nm and thehigh sensitivity of positrons to vacancy-type defects. The incorporation of H is observed after annealing at
1000°C, where the H concentration is high in the region corresponding to the Mg box profile (≤ 300 nm),and it rapidly decreases below 300 nm. The observed box profile of H is unlikely explainable assuming the
diffusion model with a constant source at the surface. Thus, the major cause of the box-shape H distribution
could be attributed to the trapping at vacancy-type defects. After 1100°C annealing, H atoms start to diffuse
toward the bulk, and as a result, the H concentration in the subsurface region decreases. A further decreasein the H concentration is observed in the subsurface region after annealing at 1200°C. For this sample, theH concentration in the region between 500 nm and 900 nm remains high, and this region reasonably agrees
with the second block (400–1100 nm) in the depth distribution of S. This can be attributed to the trappingof H by vacancy-type defects in the deep defect rich region and to a resultant suppression of the out-diffusionof H toward the surface. Above 1400°C annealing, both the depth distribution and the concentration of Mg
almost coincide with those of H, respectively. In this temperature range, because of the decrease in thevacancy concentration (Fig. 2), the number of Mg atoms at the Ga sites increases, and as a result, theinteraction between MgGa and H is likely to enhance the incorporation of H in the sample.
References[1] H. Amano et al., J. Phys. D: Appl. Phys. 51 (2018) 163001.
[2] S. O. Kucheyev et al., Mat. Sci. Eng. 33 (2001) 51.
[3] A. Uedono et al., Sci. Reports 10 (2020) 17349.
[4] J. L. Lyons et al., Phys. Rev. Lett. 108 (2012) 156403.

33

5.2

Versatile sample cooling system for Mössbauer spectroscopy using aclosed-cycle refrigerator

E. Kita, S. Ishii, Y. Tajima, T. Takahashi, Y. Yamato, T. Uchida, H. Yanagihara
Temperature dependence of Mössbauer spectra generally gives us important and useful information on
physical and magnetic properties of materials. In particular, for magnetic properties, magnetic transition
temperature is essential physical quantity related to magnetic interaction. Additionally, Mössbauer
spectroscopy (MS) is sensitive not only to a ferromagnetic order but also to an antiferromagnetic order. For
low temperature measurements, we have used a bath-type cryostat, for which fixed temperature
measurements at liquid nitrogen and helium are easily carried out, however, it is rather difficult to obtain anarbitrary temperature lower than ambient temperature. Closed-cycle refrigerators have been widely used forthe measurement apparatuses due to the convenient utility and handling. Usual closed-cycle refrigerators
generate considerable vibration resulting from mechanical motions during its operation. MS is a sensitive
measurement to such vibration because its frequency is close to the energy modulation frequency. Antivibration refrigerators have been developed and some of them are commercially available. We used a
refrigerator equipped by Iwatani Cryogenics and built up the sample cooling system.
The refrigerator includes a He condensation chamber cooled by a two-stage cooling system. A sample
stage is attached outside of the He condensation chamber which is mechanically isolated from the cold headto avoid the direct transfer of vibration of cold head, as seen in Fig. 1. The sample stage is made of oxygenfree high purity copper and is finally Au-plated as seen in Fig. 2.

Fig. 1. Illustration of the sample stage with a Pb sample
holder, two thermal shields and an outer vacuum jacket.

Fig. 2. Photo of the sample stage (Auplated).

To avoid heat transfer from the outside into the sample, two radiation shields were prepared. The first34

shield made of a Cu cylinder was set close to the sample and is depicted in Fig. 1 by the blue broken line.
The 2nd one was set between the 1st shield and the outer vacuum jacket of the refrigerator. Windows forboth thermal shields were covered with an Fe-free high purity Al foil with 20 μm in thickness. Theseradiation shields are essentially important to achieve low temperature. The lowest temperature of 2.49 K has
been obtained.
Influence of vibrations caused by motions of a cold head, a compressor and an evacuation pump for a
vacuum space was examined by measuring an α-Fe foil. The line width slightly increased by the operationof the cryostat system from 0.26 to 0.29 mm/s (FWHM).

The sample temperature was controlled by atemperature controller, Lakeshore 335. To control remotely, a LabVIEW driver was used. An example oftemperature curve during cooling is seen in Fig. 3.

To evaluate temperature stability, we havecollected MS data for FeF2 [1]. Commerciallyavailable FeF2 powder were used as received
state. FeF2 is known as an antiferromagnet
below around 80 K. The obtained spectra areshown in Fig. 4. From the temperature

Relative Transmission

Fig. 3. Temperature vs. elapsed timedependence, clear difference is seen in the
spectra between 77.526 and 78.09 K and thetransition temperature is in between 78 and 80
K. Temperature fluctuation is less than 10 mK
below 100 K.
We thank Prof. Mibu of Nagoya Institute oftechnology for the discussion on vibration.
Thanks are due to Y. Takahama for his advice
in operating the system and design of thesample stage and A. Yoshizumi for machining.
Fig. 4. Temperature dependence of Mössbauer spectraof FeF2.

Reference[1] G. K. Wertheim, D. N. E. Buchanan, Phys. Rev. 161 (1967) 478.

35

5.3

Mössbauer study of frozen magnetic fluid, Resovist

E. Kita, R. Onodera1, M. Kishimoto, H. Yanagihara
Magnetic nanoparticles (MNPs) have been developed for novel applications in addition to theirconventional applications. Recently, bio-medical application has been widely spread for such as a medical
field of therapy and diagnostics, including MNP hyperthermia, drug delivery and contrast agencies formagnetic resonance imaging (MRI). The contrast agency for MRI has already been in practical use andcommercially available. For these bio-medical applications, MNPs must be infused into human body,therefore MNPs are usually used in a form of magnetic fluid in which MNPs are stably suspended in solvent.
Magnetic property of magnetic fluid is well described by superparamagnetism due to a time dependent
magnetization behavior against an external magnetic field, so called as relaxation phenomena. Major
relaxation mechanisms in the magnetic fluid are categorized in two mechanisms; one is Brown mechanism
originated by the motion of magnetic particles in liquid and the other is Néel mechanism in which thermal
relaxation of magnetization in a small particle is responsible. Total magnetic relaxation characterized byrelaxation time of τ is composed of these two mechanisms whose characteristic times are τB and τN, i.e.,
ଵ
ఛ

ൌ

ଵ
ఛB

൅

ଵ
ఛN

.

To understand the role of two mechanisms, separation of τB and τN is essential and usually immobilized
nanoperticles have been measured to determine magnetic relaxation time, τN. Mössbauer spectroscopy (MS)
has a measuring time as fast as 10−6 s and information on relaxation can be obtained with changing thesample temperature. For this purpose, we cooled down the MS sample to immobilize NPs instead of adding
agar into the solvent. A commercially available magnetic fluid (Resovist, product of Fujifilm RI Pharma)
was used for MS measurements, which was composed of a water-based suspension of carboxydextrancoated superparamagnetic iron oxide NPs.
Figure 1 shows the dimension of a liquid sample container for an MS measurement and Fig. 2 shows aFig. 1. Illustration of a sample container for
liquid samples.
1

Fig. 2. Photograph of the sample container and thesample of Resovist.

National Institute of Technology, Ibaraki College

36photograph of the container made of an Al plate with a thickness of 3mm. Magnetic fluid was sealed with
PET thin plates from both sides using an adhesive (Scotch Premier Gold Super Multi-Purpose Glue 2, 3M)
and the sample is seen in Fig. 2.
The sample was cooled down with aclosed-cycle refrigerator and the lowest

1.00

temperature was 2.5 K [1]. Mössbauer spectra

0.98

were recorded below the freezing point of the

0.96

solvent, around 273 K.

1.00

Figure 3 shows Mössbauer spectra atdifferent

temperatures.

At

the

0.98

lowest250 K
Resovist (frozen)

200 K

0.96

temperature of 2.5 K, the spectrum was fitted

1.00

with Mössbauer parameters of maghemite (γFe2O3) and the parameters are listed in Table

0.98

1. A flat base line is observed between each

0.96

100 K

1.00

absorption peak suggesting that magnetic
ordering without an influence of magnetic

0.98

relaxation is realized. On the other hand, the

0.96

spectra recorded above 100 K are influenced

50 K

1.00

by the magnetic relaxation; the outer peak

0.96

positions are not much moved, however, the

0.92

2.5 K

line widths are significantly broadened.
-10

Additionally, a peak around the center grows

-5

0

5

10

Velocity (mm/s)

with elevating temperature. These features areunderstandable by the magnetic relaxation at

Fig. 3. Mössbauer spectra of Resovist recorded attemperatures between 2.5 K and 250 K.

Fe atom. Blume-Tjon two state magnetic
relaxation model [2] has been commonly used
to analyze MS with relaxation and we
performed fitting by using a commercially

Table 1.

Mössbauer parameters from fitting of thespectrum recorded at 2.5K.

available fitting program of MossWinn4.0.
The fitting taking into account of relaxation
rate on the spectrum recorded at 200 K
resulted in two relaxation components withSite

Hhf (kOe)

IS* (mm//s)

Area ratio (%)

A

509.7

0.535

44.8

B

530.0

0.492

55.2

*IS : with respect to α-Fe at RT

relaxation times of 5.7×10−9 s and 1.2×10−7 s.
These ranges of relaxation times will be useful to understand superparamagnetism of NPs together withother magnetic measurements reflecting their relaxation phenomena.
References[1] E. Kita et al., UTTAC Annual Report 2020, UTTAC-90 (2021) 34.
[2] M. Blume, J. A. Tjon, Phys. Rev. 165 (1968) 446.

37

5.4

Mössbauer study of Co and Mn substituted ferrite ﬁne particles

D. Hirose, M. Kishimoto, E. Kita, H. Yanagihara
Acicular ferrite ﬁne particles (FPs) have been developed as magnetic pigments for data storages suchas magnetic recording tapes and ﬂoppy disks [1]. Additionally, the usage of ﬁne/nano-particles has been
extended to various purposes, such as bio-medical ﬁelds. For these, control of magnetic properties likesaturation magnetization and anisotropy energy is still important as well as the control of size and shape ofparticles. Many studies have been carried out for this purpose and the effects of additional/substitutional
3d elements to ferrites on the basic magnetic properties have been well investigated. We have studied
Mn and Co substitution to acicular Fe3 O4 FPs to ﬁnd a new root to produce Mn and Co ferrites FPs.
Mössbauer spectroscopy was performed to understand a magnetic state of Fe atoms.
Acicular Fe3 O4 FPs with a coercive force of 370 Oe and a saturation magnetization of 78 emu/g wereused as a starting material. The starting material was dissolved in a solution of water and polyethylene
glycol including substitution elements (M) ions of Co2+ and Mn2+ ions. The mixture was treated througha hydrothermal method by using an autoclave. The precipitates were washed out with water and samples
were obtained by drying them at 60 ◦ C. Nominal concentrations of substitution elements of Co and Mn
were Co : Fe = 60 : 40 and Mn : Fe = 59 : 41, respectively. The dimension of products slightly increased
from that of the starting material, 190 nm in length and 24 nm in diameter, through the reaction.
Mössabauer spectra were recorded with a constant acceleration mode in a velocity range of ±12 mm/s.
Table 1. Summary of M substituted Fe3 O4 , (M)Fe3 O4 , FP samples and Mössbauer measurements.

Sample(Co)Fe3 O4

Element (M)Co

Concentration (M:Fe)
60 : 40

Sample ID
G1H5(Mn)Fe3 O4

Mn

59 : 41

F1C1H1

Ts
RT
2.6 K
RT
2.6 K

Measurement ID
E117
D259
E118
D257

Table 2. Fitting parameters for Co and Mn substituted acicular ferrite ﬁne particles.

SampleTs (K)RT(Co)Fe3 O4
2.6

RT(Mn)Fe3 O4
2.6

Sub-spectrum
Magnetic 1
Magnetic 2
Magnetic 3
Magnetic 1
Magnetic 2
Magnetic 3
Magnetic 1
Magnetic 2
Magnetic 3*
Magnetic 1
Magnetic 2
Magnetic 3

IS (mm/s)
0.373
0.302
0.532
0.497
0.393
0.843
0.311
0.286
0.582
0.493
0.425
0.854

QS (mm/s)–––––−0.224–––−0.023−0.010−0.141*ﬁtted with distributed Hhf

38

LW (mm/s)
0.387
0.435
0.929
0.476
0.442
1.195
0.355
0.420
(0.8)
0.482
0.566
1.067

Hhf (T)
50.9
49.3
45.6
53.6
51.2
47.2
50.1
48.9
45.5*
52.6
50.6
45.6

Area (%)
24.7
49.5
25.8
45.0
45.7
9.3
19.2
38.3
42.5
45.7
45.0
9.30

-/2+00+10/).*-',+*)('&

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!""

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"!%$

7>29?'@A;-?B--7C9--<!:-D

"!%"
3 "

3$

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759-&="!#<

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4'(25+*6---711809

4'(25+*6---711809

Fig. 1. Mössbauer spectra of Co substituted Fe3 O4 , (Co)Fe3 O4 , and Mn substituted Fe3 O4 , (Mn)Fe3 O4 ,acicular FPs. Spectra for (Co)Fe3 O4 FPs recorded at (a) room temperature and (b) 2.6 K are shown. Panels(c) and (d) display spectra for (Mn)Fe3 O4 FPs recorded at room temperature and 2.6 K, respectively.
Results of ﬁtting are also displayed by solid lines for a total ﬁtting curve (red) and sub-spectra (blue, green
and brown).

Sample temperatures (Ts ) were room temperature and 2.6 K. Low temperature was achieved with a refrigerator cryostat [2]. Experimental condition is listed in Table 1. Data were ﬁtted to a combination of threemagnetic sextets for all spectra at different temperatures by the use of a commercially available ﬁtting
program, MossWinn 4.0. Mössbauer parameters of isomer shift (IS), quadrupole splitting (QS), line width(LW) and hyperﬁne ﬁeld (H hf ) were obtained for each spectrum and are summarized in Table 2.
Figure 1 shows Mössbauer spectra of Co and Mn substituted ferrite ﬁne particles recorded at room
temperature and 2.6 K. Data are plotted with black + marks and ﬁtting results are displayed by solid lines.
It is reported that Fe3+ ions at the spinel A site show narrow line width compared with that of B site. For
Co substituted Fe3 O4 , the spectrum differs slightly from that of stoichiometric CoFe2 O4 . By comparing
the spectrum at 2.6 K with the result in reference [3], the sub-spectrum with narrower LW originates from
A site and one with broader LW from B site. The area ratios of two sites are almost equal. The spectrum
for Mn substituted Fe3 O4 recorded at RT shows high area ratio of a small H hf component with a little large
IS, which may suggest the presence of Fe2+ ions on B site [4]. This means that the amount of substituted
Mn is not high and the sample still retains properties of Fe3 O4 .
References[1] M. P. Sharrock, IEEE Trans. Magn. 25 (1989) 4374
[2] E. Kita et al., UTTAC Annual Report 2020, UTTAC-90 (2021) 34.
[3] R. M. Persoons et al., Phys. Rev. B 47 (1993) 5894.
[4] M. Popa et al., J. Am. Ceram. Soc. 91 (2008) 2488.

39

5.5

Mössbauer spectroscopy of antiferromagnetic FeMnMo alloys

F. Higashi, H. Tanimoto, E. Kita
The atomic distance in crystals increases by thermally excited lattice vibrations (thermal expansion).
Due to the thermal expansion, the elastic modulus decreases with the increase in temperature. In magnetic
materials, the atomic distance is normally increased along the magnetization direction (magnetostriction).
When the temperature rises near the magnetic phase transition temperature, the magnetostriction becomes
weaker and the atomic distance decreases with increasing temperature. Metallic materials with thetemperature insensitive mechanical properties showing nearly zero thermal expansion or constant elastic
modulus are known as Invar or Elinvar alloys. FeNi based alloys have been commercially used as Invar or
Elinvar alloys. However, the magnetic structure of ferromagnetic alloys is sensitive to the external magnetic
field and the Invar and Elinvar properties of FeNi based alloys are spoiled under magnetic field. Recently,
antiferromagnetic FeMn alloys have attracted attention as new Invar or Elinvar alloys. Masumoto et al. [1,2]. reported that FeMn alloys show the good Invar and Elinvar properties by adding 3d or 4d element. We
also found that FeMnMo alloys show the good Elinvar property. In the present study, the effect of Mo
addition on the antiferromagnetic property of FeMn alloys was investigated using Mössbauer spectroscopy.
FeMnMo alloy ingots with different concentrations were prepared using the arc furnace and the ingot
was sliced into thin plates. The sliced plates were cold rolled and annealed, and then chemically polished.
These plates of ~0.2 mm thickness, 16 mm length,

1.00

and 3 mm width were used for the dynamic Young’s

0.95

mm square piece was cut out from the plates andthinned to about 0.02 mm by mechanical polishingwith emery papers and chemical etching.
Figure 1 shows the Mössbauer spectra of the
FeMnMo alloys with different compositions. For
FeMn alloy system, it was reported that with the Mncontent above 26% the antiferromagnetic γ-phasebecomes thermally stable [3]. Quasistable ε-phasetends to be formed in FeMn alloys with the Mncontent below 24% or by cold rolling. The
paramagnetic and quasistable ε-phase considerably
appears in the Mössbauer spectrum of Fe-25.7Mn
alloy in Fig. 1. Probably, the present annealing after
cold rolling was not enough for transformation of εphase formed by cold rolling to γ-phase. By adding a
few wt% Mo to FeMn alloy, the fractional ratio of εphase is suppressed compared with the alloy without

40

Relative Transmission

modulus and X-ray diffraction measurements. A 5

0.90

25.7Mn

0.85
1.00
0.95
0.90

25.1Mn0.4Mo

1.00
0.90
0.80

24.9Mn2.2Mo

-2

-1

0

1

2

Velocity [mm/s]
Fig. 1. Mössbaure spectra of FeMnMo alloys atroom temperature. The observed data were fitted by
two components of a sextet (antiferromagnetic γphase, broken line) and a singlet (paramagnetic εphase, dotted and broken lines).

Mo, suggesting that Mo also acts as the γ-phase stabilizer element like Mn. In contrast, the results ofmagnetization measurements revealed that the effect of Mo on the magnetic properties is opposite to that of
Mn. The compositional control of Mn and Mo addition is very important for the Elinvar property at aroundroom temperature. Toward the application to modification of Elinvar alloys, further studies on the magnetic
properties as well as the texture are now in progress.
References[1] T. Masumoto et al., Mater Trans. 58 (2017) 701[2] K. Sugawara et al., Mater Trans. 59 (2018) 897.
[3] H. Umebayashi, Y. Ishikawa, J. Phys. Soc. Japan 21 (1966) 1281.

41

6.
BEAM IRRADIATION EFFECT

Photo by T. Okamoto

A sample of semiconductor device for radiation-tolerance test

6.1

Consumer LoRa device radiation resistance evaluation toward space
application

T. Kameda, T. Okamoto
We evaluated radiation resistance of the consumer LoRa communication device, Sparkfun LoRa Gateway 1-Channel shown in Fig. 1, which is a major issue when applying this device to the special spaceenvironment of radiation exposure, and vacuum [1, 2]. The reason for selecting Sparkfun LoRa Gateway
1-Channel is that it is available in Japan at a low price and is easy to do development using the Arduino
IDE. The Sparkfun LoRa Gateway 1-Channel has two semiconductor elements: the ESP32, an ultra-low
power consumption IC, and the RFM95W, a 915MHz LoRa modem.
The 6MV tandem accelerator at UTTAC is equipped with L2 beam line designed for evaluation ofradiation resistance. At this beamline, the Single Event Latchup (SEL) resistance of each semiconductor
device was evaluated by measuring the current consumption during heavy ion irradiation shown in Table1.
ESP32 was irradiated with three kinds of heavy-ion particles (Cl, F, and C), and RFM95W was irradiatedwith two kinds of heavy-ion particles (Cl and F).

Table 1. Parameters for the evaluation test

Fig. 1. Sparkfun LoRa Gateway 1-Channel

Ion

Charge

Cl
F
C

7+
5+
3+

Energy
[MeV]
48
24
24

Range in silicon
[µ m]
14.2
14.3
24.5

LET
[MeV/(mg/cm2 )]
17.3
7.2
3.6

In ESP32, SEL occurred with Cl and F, but not with C. The relationship between the inversion crosssection, obtained from the present measurements, and LET is shown in Fig. 2.
From the viewpoint of reliability engineering, the cross section was determined as if it had occurred
once even when the number of SEL occurrences was zero. Because the threshold LET of ESP32 is lessthan 10MeV/(mg/cm2 ). more detailed experiments with protons are needed for space use.
In RFM95W, no SEL occurred with all kinds of heavy ion particles, therefore RFM95W might havehigh resistance to SEL. Receiving probability during heavy-ion particle irradiation is shown in Figs. 3 and
4. As seen in Figs. 3 and 4, irradiation of heavy-ion particles reduces the reception rate and, accordingly,
further appropriate measurements are needed.

42

Fig. 2. SEL Cross section vs. LET

Fig. 3. Receiving rate vs. beam intensity (Cl)

Fig. 4. Receiving rate vs. beam intensity (F)References[1] T. Kameda, A. Nagata, UTTAC Annual Report 2018, UTTAC-88 (2019) 47.
[2] A. Nagata et al., Trans. JSASS Aerospace Tech. Japan, Vol. 17(2) (2019) 263.

43

6.2

Study on microalgae mutagenesis with 15N-resonant nuclear reaction

I. Suzuki, T. Yang, T. Ikeda, K. Sasa, S. Ishii, K. Tomita1, Y. Iwata1
The genetic improvement through random mutagenesis, which is optimized in terms of the dose of
mutagen such as effective heavy ion beams as well as typical UV-light, X-ray, gamma ray, and also suchchemical agent as ethyl-methane sulfonate, is exempted from the regulation of the genetically modified
organisms (GMO). There is still strong resistance in industry to the improvement through GMO to develop
more desirable strains with high productivity. However, it is hard to identify the genetic mutation in termsof the dose of mutagen before selecting the mutants, much less to induce a genetic mutation expressing thetarget phenotypic trait in microalgae. The authors have proposed 15N(1H, α1γ)12C resonant nuclear reaction(15N-RNR) mutagenesis, which mutates the target genes of microalgae using the 15N(1H, α1γ)12C resonant
nuclear reaction [1, 2]. Nitrogen atoms commonly form chemical bonding in DNA, in which seven nitrogenatoms are contained in every pair of adenine and thymine (AT pair) and eight nitrogen atoms in every pairof guanine and cytosine (GC pair). Substituting every nitrogen atom in DNA with a stable nitrogen isotope
15

N enriched higher than 98% in abundance, we can obtain DNA labeled with 15N isotope (15N_DNA).

Proton irradiation to 15N_DNA induces the 15N(1H, α1γ)12C resonant nuclear reaction at a resonant energy of
0.897 MeV, and the compound nucleus 16O* subsequently produces secondary heavy ions of α (4He2+) and12

C6+, which cause high-density electronic excitation of molecules near the target 15N inside 15N_DNA.

Resultantly, 15N-specific mutagenesis to DNA is possibly realized since the density of electronic excitationby the secondary ions is 26 times higher than that of the direct electronic excitation by protons at the resonant
energy. The 15N-RNR mutagenesis has an advantage exceeding heavy ion irradiation of the conventionalrandom mutagenesis, where a whole cell is exposed to high-density excitation. The 4.43 MeV gamma-rays
emitted from 15N(1H, α1γ)12C RNR are monitored from the outside of the vacuum irradiation system, whichenables to accurately evaluate genetic mutation taken
in 15N_DNA during proton beam irradiation.
The authors have demonstrated denaturation of
15

N_DNA induced by the 15N(1H, α1γ)12C RNR, using

UV spectrophotometry. UV spectrophotometry at 260
nm

absorbanceiscommonly

used

for

the

quantification of nucleic acids. Figure 1 shows UV
absorbance spectra of pUC4-KIXX, which is a
plasmid DNA composed of 3914 bps and has two
kinds of resistance genes (R-Ampicillin and RKanamycin). Hyperchromicity, i.e., increase inabsorbance, possibly occurs by denaturation of the Fig. 1. Optical absorbance spectra of pUC4-KIXX
plasmid DNA. 260 nm absorbance is used to quantify
double-strand DNA structure separated into single
the concentration of nucleic acids.
1

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

44

strands [3].
The radiation effects of proton
irradiation on the 15N-labeled (98%enriched)

pUC4-KIXX

natural (0.364%

15

and

the

N in abundance)

pUC4-KIXX have been investigatedby measuring 260 nm absorbance.
Proton beam irradiation was carriedout at energies from 0.884 to 0.906
MeV around the resonant energy of
0.897

MeV using

the

1

MV

Tandetron accelerator at UTTAC.
The typical beam current was 1 nA in
the target area of 8.3 mm2. The 4.43
MeV gamma-rays emitted from the15

N(1H, α1γ)12C RNR were detectedwith a BGO (Bi4Ge3O12) scintillation
detector.

Fig. 2. Absorbance of the 15N-labeled and natural pUC4-KIXX
plasmids. Intense hyperchromicity of absorbance appears moresignificantly in the 15N-labeled plasmids.

Figure 2 shows the optical absorbance of pUC4-KIXX as a function of the proton dose. Hyperchromicity
is observed throughout doses from 0.5 to 10 μC. In the lower dose range, the absorbance of both the 15Nlabeled and natural plasmids take the same values and monotonically increase. With increasing the dose
higher than 2.5 μC, the absorbance of the natural plasmid decreases, while the absorbance of the 15N-labeledplasmid still increases up to 5 μC and then decreases. Intense hyperchromicity of absorbance appears moresignificantly in the 15N-labeled plasmids, which suffer radiobiological damage by the 15N(1H, α1γ)12C RNR.
The denaturation of double-strand DNA into single strands is one of the possible factors of hyperchromicity,and the decrease in the absorbance indicates damage of the molecular structures of nucleic acids.
In conclusion, the authors clarified the denaturation of 15N-labeled pUC4-KIXX plasmid DNA inducedby the 15N(1H, α1γ)12C RNR. Intense hyperchromicity in the 260 nm absorbance appears more significantlyin the 15N-labeled plasmid DNA.

References[1] Y. Iwata et al., European Advanced Materials Congress (EAMC2019), Stockholm during 11–14 August(2019).
[2] Y. Iwata et al., PCT/JP2020/030476, WO/2021/029391, February 18 (2021).
[3] A. O. Nwokeoji et al., Anal. Chem. 89 (2017) 13567.

45

7.
LIST OF PUBLICATIONS AND PRESENTATIONS

7.1

Journals

ACCELERATOR AND RELATED FACILITIES
1. H. Matsumura, G. Yoshida, A. Toyoda, K. Masumoto, H. Nakamura, T. Miura, K. Nishikawa,
K. Bessho, K. Sasa, T. Moriguchi, F. Nobuhara, Y. Nagashima, “Nondestructive High-Sensitivity
Measurement Method for Activation Estimation in Accelerator Room Concrete”, Radiation Protection
40(6) (2020) 677.
2. K. Masumoto,

H. Matsumura,T. Miura,

G. Yoshida,

A. Toyoda,

H. Nakamura,

K. Bessho,

T. Nakabayashi, F. Nobuhara, K. Sasa, T. Moriguchi, H. Tsuchida, S. Matsuyama, M. Matsuda,
A. Taniike,“Evaluation of activated area in the electrostatic accelerator facilities”,

Radiation

Protection 41(2) (2021) 145.
3.

G. Yoshida, H. Matsumura, H. Nakamura, A. Toyoda, K. Masumoto, T. Miura, K. Sasa, T. Moriguchi,“Survey Methodology for the Activation of Beamline Components in an Electrostatic Proton
Accelerator”, Radiat. Saf. Manage. 20 (2020) 1.

NUCLEAR AND ATOMIC PHYSICS
1.

Y. X. Watanabe, M. Ahmed, Y. Hirayama, M. Mukai, J. H. Park, P. Schury, Y. Kakiguchi, S. Kimura,A. Ozawa, M. Oyaizu, M. Wada, H. Miyatake, “Deexcitation γ-ray transitions from the long-lived Iπ =13/2+ metastable state in 195Os”, Phys. Rev. C 101 (2020) 041305(R).

2.

D. Nagae, Y. Abe, S. Okada, S. Omika, K. Wakayama, S. Hosoi, S. Suzuki, T. Moriguchi, M. Amano,
D. Kamioka, Z. Ge, S. Naimi, F. Suzaki, N. Tadano, R. Igosawa, K. Inomata, H. Arakawa,
K. Nishimuro, T. Fujii, T. Mitsui, Y. Yanagisawa, H. Baba, S. Michimasa, S. Ota, G. Lorusso,
Yu.A. Litvinov, A. Ozawa, T. Uesaka, T. Yamaguchi, Y. Yamaguchi, M. Wakasugi, “Development
and operation of an electrostatic time-of-flight detector for the Rare RI storage Ring”, Nucl. Instrum.
Methods Phys. Res. A 986 (2021) 164713.

3.

S. Naimi, H.F. Li, Y. Abe, Y. Yamaguchi, D. Nagae, F. Suzaki, M. Wakasugi, H. Arakawa, W. Dou,
D. Hamakawa, S. Hosoi, Y. Inada, K. Inomata, D. Kajiki, T. Kobayashi, M. Sakaue, K. Yokoya,
T. Yamaguchi, R. Kagesawa, D. Kamioka, T. Moriguchi, M. Mukai, A. Ozawa, S. Ota, N. Kitamura,
S. Masuaoka, S. Michimasa, D. S. Ahn, H. Baba, N. Fukuda, Y. Shimizu, H. Suzuki, H. Takeda,
C.Y. Fu, Z. Ge, S. Suzuki, Q. Wang, M. Wang, Yu.A. Litvinov, G. Lorusso, T. Uesaka, “Experimental
Challenges of the First Mass Measurement Campaign at the Rare-RI Ring”, J. Phys. Conf. Ser. 1643

46

(2020) 012058.
4.

T. Moriguchi, M. Amano, A. Ozawa, W. Horiuchi, Y. Abe, T. Fujii, R. Kagesawa, D. Kamioka,
A. Kitagawa, M. Mukai, D. Nagae, M. Sakaue, S. Sato, S. Suzuki, T. Suzuki, T. Yamaguchi, K. Yokota,“Measurements of total reaction cross sections for 17Ne using a solid hydrogen target”, J. Phys. Conf.
Ser. 1643 (2020) 012099.

5.

A. Homma, M. Tanaka, M. Takechi, T. Ohtsubo, M. Fukuda, T. Suzuki, D. Nishimura, T. Moriguchi,
D. S Ahn, A. S Aimaganbetov, M. Amano, H. Arakawa, S. Bagchi, K.-H. Behr, N. Burtebayev,
K. Chikaato, H. Du, T. Fujii, N. Fukuda, H. Geissel, T. Hori, S. Hoshino, R. Igosawa, A. Ikeda,
N. Inabe, K. Inomata, K. Itahashi, T. Izumikawa, D. Kamioka, N. Kanda, I. Kato, I. Kenzhina,
Z. Korkulu, Ye. Kuk, K. Kusaka, K. Matsuta, M. Mihara, E. Miyata, D. Nagae, S. Nakamura,
M. Nassurlla, K. Nishimuro, K. Nishizuka, S. Ohmika, K. Ohnishi, M. Ohtake, H.J. Ong, A. Ozawa,A. Prochazka, H. Sakurai, C. Scheidenberger, Y. Shimizu, T. Sugihara, T. Sumikama, S. Suzuki,
H. Suzuki, H. Takeda, Y. Tanaka, Y. K. Tanaka, T. Wada, K. Wakayama, S. Yagi, T. Yamaguchi,
R. Yanagihara, Y. Yanagisawa, K. Yoshida, T. K. Zholdybayev, “Development of a Method to Deduce
Point-proton Radii from Charge Changing Cross Sections”, JPS Conf. Proc. 32 (2020) 010032.

6.

M. Mukai, Y. Hirayama, Y. X. Watanabe, S. Schiffmann, J. Ekman, M. Godefroid, P. Schury,
Y. Kakiguchi, M. Oyaizu, M. Wada, S. C. Jeong, J. Y. Moon, J. H. Park, H. Ishiyama, S. Kimura,
H. Ueno M. Ahmed, A. Ozawa, H. Watanabe, S. Kanaya, H. Miyatake, “In-gas-cell laser resonanceionization spectroscopy of 196,197,198Ir”, Phys. Rev. C 102 (2020) 054307.

7.

C. Y. Fu, Y. H. Zhang, M. Wang, X. H. Zhou, Yu. A. Litvinov, K. Blaum, H. S. Xu, X. Xu, P. Shuai,
Y. H. Lam, R. J. Chen, X. L. Yan, X. C. Chen, J. J. He, S. Kubono, M. Z. Sun, X. L. Tu, Y. M. Xing,
Q. Zeng, X. Zhou, W. L. Zhan, S. Litvinov, G. Audi, T. Uesaka, T. Yamaguchi, A. Ozawa, B. H. Sun,
Y. Sun, F. R. Xu, “Mass measurements for the Tz = -2 f p-shell nuclei 40Ti, 44Cr, 46Mn, 48Fe, 50Co, and52Ni”, Phys. Rev. C 102 (2020) 054311.

ACCELERATOR MASS SPECTROMETRY
1. Kimikazu Sasa, Maki Honda, Seiji Hosoya, Tsutomu Takahashi, Kenta Takano, Yuta Ochiai, Aya
Sakaguchi, Saori Kurita, Yukihiko Satou, Keisuke Sueki, “A sensitive method for Sr-90 analysis byaccelerator mass spectrometry” J. Nucl. Sci. Tech. 58(1) (2021) 72-79.
[DOI: 10.1080/00223131.2020.1801530]
2. Masumi Matsumura, Kimikazu Sasa, Tetsuya Matsunaka, Keisuke Sueki, Tsutomu Takahashi,
Hiroyuki Matsuzaki, “Assessing the effect of laboratory environment on sample contamination for

47

I-129 accelerator mass spectrometry”, Anal. Sci. 36(5) (2020) 531. [DOI: 10.2116/ analsci.20SBN05]

BEAM AND ISOTOPE APPLICATIONS
1. M. Kurosawa, K. Sasa, S. Ishii, “Quantitative PIXE analyses of trace Ti in single fluid inclusions inquartz from Tsushima granite”, Nucl. Instrum. Methods Phys. Res. B 479 (2020) 35.
2. T. Yamamoto, A. Chikamatsu, S. Kitagawa, N. Izumo, S. Yamashita, H. Takatsu, M. Ochi,
T. Maruyama, M. Namba, W. Sun, T. Nakashima, F. Takeiri, K. Fujii, M. Yashima , Y. Sugisawa,
M. Sano, Y. Hirose, D. Sekiba, C. M. Brown, T. Honda, K. Ikeda, T. Otomo, K. Kuroki, K. Ishida,
T. Mori, K. Kimoto ,T. Hasegawa, H. Kageyama, “Strain-induced creation and switching of anion
vacancy layers in perovskite oxynitrides”, Nat. Commun. 11 (2020) 5923.
3. K. Hirota, G. Ichikawa, S. Ieki, T. Ino, Y. Iwashita, M. Kitaguchi, R. Kitahara, J. Koga, K. Mishima,
T. Mogi, K. Morikawa, A. Morishita, N. Nagakura, H. Oide, H. Okabe, H. Otono, Y. Seki, D. Sekiba,
T. Shima, H. M. Shimizu, N. Sumi, H. Sumino, T. Tomita, H. Uehara, T. Yamada, S. Yamashita, K.
Yano, M. Yokohashi, T. Yoshioka, “Neutron lifetime measurement with pulsed cold neutrons”, Prog.
Theor. Exp. Phys. 2020 (2020) 123C02.
4. T. Wakasugi, Y. Hirose, S. Nakao, Y. Sugisawa, D. Sekiba, T. Hasegawa, “High-Quality
Heteroepitaxial Growth of Thin Films of the Perovskite Oxynitride CaTaO2N: Importance ofInterfacial Symmetry Matching between Films and Substrates”, ACS Omega 5 (2020) 1339.
5. S. Yamada, R. Shigesawa, H. Latiff, M. Kishimoto, E. Kita, H. Yanagihara, “Magnetic Properties of
Tetragonal Cobalt Manganese Ferrite Particles Prepared Using the Molten Salt Method”, IEEE Trans.
Magn. 56(4) (2020) 6702618.
6. R. Murase, H. Tsuchida, S. Tomita, A. Chiba, K. Nakajima, T. Majima, M. Saito, “Effects of molecularaxis orientation of MeV diatomic projectiles on secondary ion emission from biomolecular targets”,
Nucl. Instrum. Meth. Phys. Res. B 478 (2020) 284.
7. M. Sumiya, M. Sumita, Y. Asai, R. Tamura, A. Uedono, A. Yoshigoe, “Dynamic Observation andTheoretical Analysis of Initial O2 Molecule Adsorption on Polar and m-Plane Surfaces of GaN”, J.
Phys. Chem. 124 (2020) 25282-25290. [DOI: 10.1021/acs.jpcc.0c07151]
8. A. Uedono, H. Sakurai, T. Narita, K. Sierakowski, M. Bockowski, J. Suda, S. Ishibashi, S. F. Chichibu,
T. Kachi, “Effects of ultra-high-pressure annealing on characteristics of vacancies in Mg-implanted
GaN studied using a monoenergetic positron beam”, Sci. Rep. 10 (2020) 17349 (1-7). [DOI:48

10.1038/s41598-020-74362-9]
9. F. Inoue, A. Podpod, L. Peng, A. Phommahaxay, K. J. Rebibis, A. Uedono, E. Beyne, “Morphologicalcharacterization and mechanical behavior by dicing and thinning on direct bonded Si wafer”, J. Manuf.
Process. 58 (2020) 811-818. [DOI: 10.1016/j.jmapro.2020.08.050]
10. A. Uedono, K. Shojiki, K. Uesugi, S. F. Chichibu, S. Ishibashi, M. Dickmann, W. Egger, C.
Hugenschmidt, H. Miyake, “Annealing behaviors of vacancy-type defects in AlN deposited by radiofrequency sputtering and metalorganic vapor phase epitaxy studied using monoenergetic positron
beams”, J. Appl. Phys. 128 (2020) 085704(1-10). [DOI: 10.1063/5.0015225]
11. S. Chang, M. Zhao, V. Spampinato, A. Franquet, T.-H. Do, A. Uedono, T. T. Luong, T.-H. Wang,
L. Chang, “The Influence of AlN Nucleation Layer on Radio Frequency Transmission Loss of AlN‐
on‐Si Heterostructure”, Phys. Stat. Sol. (a) 217 (2020) 1900755(1-6). [DOI: 10.1002/pssa.201900755]
12. H. J. Zhang, S. Sellaiyan, K. Sako, A. Uedono, Y. Taniguchi, K. Hayashi, “Effect of Free-Volume Hole
Fraction on Dynamic Mechanical Properties of Epoxy Resins Investigated by Pressure-VolumeTemperature Technique”, J. Phys. Chem. B 124 (2020) 1824-1832. [DOI : 10.1021/acs.jpcb.9b10978]
13. A. Uedono, W. Ueno, T. Yamada, T. Hosoi, W. Egger, T. Koschine, C. Hugenschmidt, M. Dickmann,
H. Watanabe, “Voids and vacancy-type defects in SiO2/GaN structures probed by monoenergetic
positron beams”, J. Appl. Phys. 127 (2020) 054503(1-8). [DOI: 10.1063/1.5134513]
14. A. Sagara, H. Yabe, X. Chen, P.M. Vereecken, A. Uedono, “Pore structure analysis of ionic liquidtemplated porous silica using positron annihilation lifetime spectroscopy”, Microporous Mesoporous
Mat. 295 (2020) 109964(1-7). [DOI: 10.1016/j.micromeso.2019.109964]
15. N. Qi, X. Zhang, Z. Q. Chen, F. Ren, B. Zhao, M. Jiang, A. Uedono, “Selective trapping of positronsby Ag nanolayers in a V/Ag multilayer system”, AIP Adv. 10 (2020) 035012(1-7).
[DOI: 10.1063/1.5143379]
16. H. J. Zhang, S. Sellaiyan, K. Sako, A. Uedono, Y. Taniguchi, K. Hayashi, “Effect of free-volume holeson static mechanical properties of epoxy resins studied by positron annihilation and PVT experiments”,
Polymer 190 (2020) 122225(1-9). [DOI: 10.1016/j.polymer.2020.122225]
17. G. A. Jacob, S. Sellaiyan, A. Uedono, R. J. Joseyphus, “Magnetic properties of metastable bcc phasein Fe64Ni36 alloy synthesized through polyol process”, Appl. Phys. A 126 (2020) 120(1-7).
[DOI: 10.1007/s00339-020-3292-3]

49

18. T. Kimura, K. Kataoka, A. Uedono, H. Amano, D. Nakamura, “Growth of high-quality GaN by
halogen-free vapor phase epitaxy”, Appl. Phys. Express 13 (2020) 085509(1-5).
[DOI: 10.35848/1882-0786/aba494]
19. S. F. Chichibu, A. Uedono, K. Kojima, K. Koike, M. Yano, S. Gonda, S. Ishibashi, “Hole capturecoefficient of intrinsic nonradiative recombination centers that commonly exist in bulk, epitaxial, andproton-irradiated ZnO”, Appl. Phys. Lett. 127 (2020) 215704(1-6). [DOI: 10.1063/5.0011309]

7.2

Reviews and books

1. 笹 公和，“難測定核種の加速器質量分析による高感度検出手法の開発”，応用物理学会放射線分科会会誌「放射線」45(3) (2020) 128.

2. D. Sekiba, “Nuclear Methods in Surface Science” In: Rocca M., Rahman T.S., Vattuone L. (eds)
Springer Handbook of Surface Science. Springer Handbooks. Springer, Cham.
https://doi.org/10.1007/978-3-030-46906-1_39

7.3

Poster or oral presentations at academic meetings

1.

A. Uedono, H. Sakurai, T. Narita, K. Sierakowski, M. Bockowski, J. Suda, S. Ishibashi, S. F. Chichibu,
T. Kachi, “Behaviors of vacancy-type defects in Mg-implanted GaN during ultra-high-pressure
annealing studied by using a monoenergetic positron beam”, SPIE Photonics West, OPTO, San
Francisco, USA (Mar. 6, 2021).

2.

(Invited Talk)

A. Uedono, H. Iguchi, T. Narita, K. Kataoka, W. Egger, T. Koschine, C. Hugenschmidt, M. Dickmann,
K. Shima, K. Kojima, S. F. Chichibu, S. Ishibashi, “Interaction between hydrogen and vacancy-type
defects in Mg-implanted GaN studied by monoenergetic positron beams”, Int. Work. Positron Study
Defects, on-line (Mar. 3, 2021).

3.

(Invited Talk)

A. Uedono, M. Dickmann, W. Egger, C. Hugenschmidt, S. Ishibashi, “A study of vacancy-type defects
in wide-gap semiconductors by means of positron annihilation spectroscopy”, MLZ User Meeting
and German Neutron Scattering Conf., Germany (Dec. 8, 2020). (Invited Talk)

4.

上殿明良， 高島信也， 江戸雅晴， 上野勝典， 松山秀昭，M. Dickmann，W. Egger，C. Hugenschmidt，嶋紘平，小島一信，秩父重英，石橋章司，“陽電子消滅法による Mg イオン注入 GaN の空孔型欠陥の焼鈍特性及び欠陥によるキャリア捕獲の研究”, 先進パワー
半導体分科会－応用物理学会, オンライン開催

50(2020 年 11 月 16 日). （招待講演）

5.

上殿明良，櫻井秀樹，成田哲生，K. Sierakowski，M. Bockowski，須田嶋紘平，秩父重英，加地淳，石橋章司，徹，“陽電子を用いた超高圧焼鈍によるイオン注入 GaN の欠陥

回復特性の研究”, 第 49 回結晶成長国内会議, オンライン開催 (2020 年 11 月 9 日).
（招待講演）
6.

A. Ozawa, “Present status of Rare-RI Ring (R3) and mass measurements”, RIBF Users Meeting 2020,
RIKEN, on-line (Sep. 8-10, 2020).

7.

冨田成夫, 山崎明義, 石井(Invited Talk)

聰, 笹 公和, 左高正雄, 楢本洋, 工藤博, “透過 ERDA によるアルミニウム中の水素 3 次元計測”, 第 68 回応用物理学会春季学術講演会シンポジウム「イオンビーム分析の最前線と展望」,

オンライン開催(2021 年 3 月 16-19 日).

（招待講演）
8.

笹公和，“加速器質量分析を用いた宇宙線生成核種および人為起源核種の環境動態研究”，

金沢大学環日本海域環境研究センター セミナー, 金沢大学 (2020 年 11 月 17 日).
（招待講演）
9.

A. Sakaguchi, “Accelerator mass spectrometry analyses of ultra-trace radionuclides in theenvironment - application to geosciences studies”, Forum for Nuclear Cooperation in Asia,(Mar. 3-4, 2021).

(Invited Talk)

10. 上殿明良，正直花奈子，上杉謙次郎，秩父重英，石橋章司，M. Dickmann，W. Egger，C. Hugenschmidt，三宅秀人，”陽電子消滅によるスパッタ堆積 AlN 薄膜中の空孔型欠陥検出”，第 68 回応用物理学会春季学術講演会, オンライン開催 (2021 年 3 月 19 日).
11. 秩父重英，嶋紘平，小島一信，B. Moody，三田清二，R. Collazo，Z. Sitar，熊谷義直，

上殿明良，“AlN 単結晶上に HVPE 成長させた Si 添加 AlN 基板の発光特性”, 第 68 回応用物理学会春季学術講演会, オンライン開催 (2021 年 3 月 19 日).
12. 嶋

紘平，田中

亮，高島信也，上野勝典，江戸雅晴，小島一信，上殿明良，秩父重英，“Mg イオン注入後の空孔ガイド拡散法により形成した p 型 GaN のルミネッセンス評価”，
第 68 回応用物理学会春季学術講演会, オンライン開催 (2021 年 3 月 18 日).
13. 角谷正友，高原悠希，今中康貴，A. Amira，G. Andersson，竹端寛治，上殿明良，“AlN テン
プレート上 AlGaN/InxGa1-xN ヘテロ構造の成長”, 第 81 回応用物理学会秋季学術講演会, オ
ンライン開催 (2020 年 9 月 10-13 日).
14. 上殿明良, 上野航，細井卓治，Egger Werner，Hugenschmidt Christoph，Dickmann Marcel，

渡部平司，“陽電子消滅による GaN 基板上に成膜した TEOS-SiO2 膜の空隙の検出” 第 81 回

51

応用物理学会秋季学術講演会, オンライン開催 (2020 年 9 月 10 日).
15. 嶋

紘平，正直花奈子，上杉謙次郎，小島一信，上殿明良，三宅秀人，秩父重英，“高温アニールスパッタ AlN 上に MOVPE 成長させた AlN の陰極線蛍光評価(1)”, 第 81 回応用物理学会秋季学術講演会, オンライン開催 (2020 年 9 月 10-13 日).
16. 粕谷拓生，嶋紘平，正直花奈子，上杉謙次郎，小島一信，上殿明良，三宅秀人，

秩父重英，“高温アニールスパッタ AlN 上に MOVPE 成長させた AlN の陰極線蛍光評価(2)”,
第 81 回応用物理学会秋季学術講演会, オンライン開催 (2020 年 9 月 10-13 日).
17. M. Muralidharan, S. Sellaiyan, A. Uedono, K. Sivaji, M. Avinash, A. Kumari, “Investigation onvacancy type defects in Fe doped SrSnO3 perovskite nanostructures by Positron annihilation
spectroscopy”, Int. Work. Positron Study Defects, on-line (Mar. 3, 2021).
18. T. Kasuya, K. Shima, K. Shojiki, K. Uesugi, K. Kojima, A. Uedono, H. Miyake, S. F. Chichibu,“Cathodoluminescence studies of AlN epilayers grown by MOVPE on sputtered AlN templates
annealed at high temperature”, 8th Asian Conf. Cryst. Growth and Cryst. Tech., On-line (Mar. 1-3,2021).
19. A. Uedono, K. Shojiki, K. Uesugi, S. F. Chichibu, S. Ishibashi, M. Dickmann, W. Egger, C.
Hugenschmidt, H. Miyake, “Vacancies in AlN deposited by radio-frequency sputtering and MOVPE
studied by positron annihilation spectroscopy”, 8th Asian Conf. Cryst. Growth and Cryst. Tech., On
line (Mar. 1-3, 2021).
20. M. Sumiya, Y. Takahara, A. Alghamdi, G. Andersson, A. Uedono, Y. Imanaka, “Growth of
AlxGa1-xN/InyGa1-yN hetero structure on AlN/sapphire templates”, 8th Asian Conf. Cryst. Growth andCryst. Tech., On-line (Mar. 1-3, 2021).
21. 冨田啓介, 小沢顕, 森口哲朗, 向井もも, 大和良広, 景澤怜央,”29P の核磁気モーメントの符号測定”, 日本物理学会 2020 年秋季大会, オンライン開催 (2020 年 9 月 14-17 日).
22. S. Tomita, Y. Shiina, R. Suganuma, M. Matsuda, M. Imai, M. Sataka, K. Sasa, “The threshold foil
thickness for the disappearance of the vicinage effect on the convoy-electron yield”, 第 21 回「イオンビームによる表面・界面の解析と改質」特別研究会, 京都大学宇治キャンパス, 現地会場とオンラインのハイブリッド形式開催
23. 東(2020 年 12 月 4-5 日).

史弥, 谷本久典, “Fe-Mn 系反強磁性合金の圧延・焼鈍による組織変化とエリンバー特性”、2020 年日本金属学会秋期講演会, オンライン開催 (2020 年 9 月 17 日).

52

24. 東史弥, 喜多英治, 谷本久典,“Fe-Mn 系反強磁性合金のエリンバー特性と組織および磁性”、2021 年日本金属学会春期講演会, オンライン開催 (2021 年 3 月 18 日).
25. 菅澤佳世，三宅芙沙，多田悠馬，堀内一穂，大谷

昴，笹

公和，高橋

努，松村万寿美，

落合悠太，望月優子，高橋和也，中井陽一，本山秀明，松崎浩之，“約 100 年分のドームふじアイスコア中 10Be と 36Cl の高分解能測定による BC5480 年宇宙線イベントの調査”，第81 回応用物理学会秋季学術講演会, オンライン開催 (2020 年 9 月 8-11 日).
26. 大石脩人, 村尾吉輝, 新田紀子, 土田秀次, 冨田成夫, 笹公和, 平田浩一，柴田裕実, 平野

貴美, 山田圭介, 千葉敦也, 斎藤勇一, 鳴海一雅, 星野靖，“C60 クラスターイオンビーム照射による Si 表面構造の形成”, 第 81 回応用物理学会秋季学術講演会, オンライン開催 (2020年 9 月 8-11 日).
27. 笹

公和，高橋

努，松村万寿美，“36Cl の加速器質量分析における妨害同重体 36S の除去方法の検討”，第 81 回応用物理学会秋季学術講演会，オンライン開催 (2020 年 9 月 8-11 日).
28. 笹

公和, 石井聰，高橋努，大和良広， 田島義一，松村万寿美，森口哲朗，“筑波大学

タンデム加速器施設の現状報告”, オンライン開催 第 17 回日本加速器学会年会 (2020 年 9
月 2-4 日).
29. 黒澤正紀，笹公和，石井聰，“対馬花崗岩の流体包有物中のニッケル”，日本鉱物科学会

2020 年年会, オンライン開催 (2020 年 9 月 16-17 日).
30. 小林成, 杉澤悠紀, 岸奈津子, 西尾和記, 関場大一郎, 清水亮太, 一杉太郎，“清浄な全固体 Li 電池界面のイオンビーム観察”, 日本表面真空学会学術講演会年会,

オンライン開催 (2020 年 11 月 19-21 日).
31. N. Oishi, Y. Murao, N. Nitta, H. Tsuchida, S. Tomita, K. Sasa, K. Hirata, H. Shibata, Y. Hirano, K.
Yamada, A. Chiba, Y. Saitoh, K. Narumi, Y. Hoshino, “Energy dependence of nanostructureformation by fast C60 cluster ion beam on Si”, 第 21 回「イオンビームによる表面・界面の解析と改質」特別研究会, 京都大学宇治キャンパス, 現地会場とオンラインのハイブリッド形式
開催
32. 笹

(2020 年 12 月 4-5 日).

公和，山崎明義，石井聰，冨田成夫，左高正雄，楢本洋，工藤博，“構造材料用

マイクロビーム装置における多元素同時分析のためのイオンビーム分析システム”, 2021 年
第 68 回応用物理学会春季学術講演会, オンライン開催 (2021 年 3 月 16-29 日).
33. 脇山義史，松村万寿美，松中哲也，平尾茂一，笹公和，“阿武隈川における出水時の 129Iの挙動”, 第 7 回福島大学環境放射能研究所成果報告会, コラッセふくしま

53

(2021 年 3 月 18 日).
34. 中村

司，山﨑

信哉，石井

聰，冨田成夫，左高正雄，楢本洋，工藤

博，笹

公和，

末木啓介，“マイクロビーム PIXE による福島第一原子力発電所事故で放出した放射性粒子の元素分布測定”, 第 22 回「環境放射能」研究会, オンライン開催 (2021 年 3 月 10-12 日).
35. 松本翔汰, 阪上朱音, 関屋涼平, 辻崚太郎, 板橋健太, 上坂友洋, 西隆博, 銭廣十三,

矢向謙太郎, 森口哲朗, ”高精度パイ中間子原子分光・二重ガモフ―テラー巨大共鳴探索実
験のための新 MWDC の開発”, 日本物理学会第 76 回年次大会, オンライン開催(2021 年 3 月 13 日).
36. 木村容子, 三原基嗣, 松多健策, 福田光順, 大谷優里花, 高山

元, 泉川卓司, 野口法秀,

生越瑞揮, 佐藤弥紗, 高津和哉, 大坪隆, 髙橋弘幸, 百田佐多生, 奥村寛之, 森口哲朗,
小沢顕, 北川敦志、佐藤眞二, “ハルバッハ配列磁石を用いた小型 β-NMR 装置の開発”, 令和
2 年度京大複合研専門研究会「短寿命 RI を用いた核分光と核物性研究 VII」, オンライン開催 (2021 年 1 月 15 日).
37. 木村容子, 三原基嗣, 松多健策, 福田光順, 大谷優里花, 高山
生越瑞揮, 佐藤弥紗, 高津和哉, 大坪

元, 泉川卓司, 野口法秀,隆, 髙橋弘幸, 百田佐多生, 奥村寛之, 森口哲朗,

小沢 顕, 北川敦志, 佐藤眞二, “ハルバッハ配列磁石を用いた小型 β-NMR 装置の開発”,
日本物理学会第 76 回年次大会, オンライン開催 (2021 年 3 月 12-15 日).

7.4

UTTAC seminars

2021. 1. 13

Search for baryon bound state by correlation function measurement using Λ and Ξ
particles in √𝑠= 200 GeV Au+Au collision at RHIC-STAR experiment, Moe Isshiki(University of Tsukuba)
2021. 1. 13

Verification of nuclear theoretical model and extraction of optimum parameters using
unified framework (JETSCAPE) that describes high-energy nuclear collision events,
Naoto Ito (University of Tsukuba)

2021. 1. 13

Measurements of global polarization of Lambda hyperons in Au+Au collisions at √𝑠=

3.0, 7.2, 54.4 GeV with RHIC-STAR experiment, Kosuke Okubo (University of Tsukuba)
2021. 1. 13

Centrality determination with the Event Plane Detector and measurements of higher order
cumulants of net-proton distributions in Au+Au collisions at √𝑠STAR, Yuri Sato (University of Tsukuba)

54= 27 GeV from2021. 1. 13

Measurement of the sign of nuclear moment for unstable nuclei 29P, 25Al by using rotating
magnetic field, Keisuke Tomita (University of Tsukuba)

2021. 1. 15

Measurement of electron v2 from bottom quark in Pb-Pb collisions at 5.02 TeV at LHCALICE experiment, Yuku Sudo (University of Tsukuba)

2021. 1. 15

Performance evaluation of Multi-gap Resistive Plate Chamber (MRPC) for time-of-flightdetector in J-PARC E16 experiment and development of new MRPC, Kosuke Tsukui(University of Tsukuba)

2021. 1. 15

Centrality determination using Event Plane Detector in √𝑠 = 27 GeV Au-Au
collisions at RHIC-STAR experiment, Ryoma Nakazato (University of Tsukuba)

2021. 1. 15

Measurement of Full Jet using track detectors and electromagnetic calorimeters in p-p
collision at 13TeV at LHC-ALICE experiment, Keisuke Yasaki (University of Tsukuba)

2021. 1. 15

Measurements of directed flow in √𝑠= 19.7 GeV Au-Au collision at RHIC-STAR

experiment, Taichi Ichisawa (University of Tsukuba)

55

8.
THESES

Master theses
Keisuke Tomita

Measurement of the sign of nuclear moment for unstable nuclei 29P, 25Al byusing rotating magnetic field (回転磁場を利用した不安定核 29P, 25Al の
核磁気モーメントの符号測定)

Sota Yamada

Magnetic Properties and Synthesis of Ferrite Nanoparticles with an AcicularCore-shell Structure (針状コア/シェル構造を持つスピネルフェライト
ナノ粒子の合成と特性評価)

Fumiya Higashi

Texture, Elasticity and Magnetism of Fe-Mn Based Ternary Elinvar Alloys(FeMn 基３元系エリンバー合金の組織と磁気及び弾性特性)

Masato Inoue

Analysis of Vacancy-type Defects in BN Using Positron Annihilation
Spectroscopy (陽電子消滅法を用いた BN の空孔型欠陥の評価)

Ryuta Yaguchi

Analysis of Vacancy-type Defects in CuMn Using Positron Annihilation
Spectroscopy (陽電子消滅法による CuMn 内空孔型欠陥の評価)

Yuhki Takahara

Fabrication of AlGaN/GaN Hetero-structure on AlN Template for GaNHEMT Device Application (GaN-HEMT デバイスに向けた AlN テンプ
レート上 AlGaN/GaN ヘテロ構造の作製)

Yuhta Kurosaki

Study of Influential Factors of High-Temperature Annealing on Electrode/ntype AlN Interface Structure (高温熱処理による電極/ｎ型 AlN 界面構
造への影響に関する研究)

Undergraduate theses
Takehiro Okamoto

ASSESSING THE FEASIBILITY OF A LOW ORBIT LORA RELAYSATELLITE (低軌道 LoRa 中継衛星のフィージビリティ評価)

Mika Hayashi

Measurements of ejectile particles from arc plasma deposition source(アークプラズマ蒸着源からの出射粒子の測定)

Asahi Yano

Study of p⃗ + .Si reaction in UTTAC 6MV tandem accelerator (UTTAC
6MV タンデム加速器における p⃗ + .Si 反応の研究)

Ginga Kawasaki

Depth and lateral resolution of transmission ERDA analysis for the three
dimensional distribution of hydrogen in aluminum (透過型 ERDA を用いた Al 中 3 次元水素分析の分解能評価)

Souta Hatada

Development of two-dimensional data acquisition system of time of flightand pulse height using FPGA (FPGA ボードを用いた飛行時間-波高 2
次元計測システムの開発)

56

Tsukasa Nakamura

Element distributions of radioactive particles emitted in the Fukushima
Daiichi Nuclear Power Plant accident by microbeam PIXE (マイクロビ
ーム PIXE による福島第一原子力発電所事故で放出された放射性粒子の元素分布測定)

Akane Taira

Fabrication of Ionization Chamber for TOF-E telescope ERDA (TOF-E
telescope ERDA 用電離箱の製作)

57

9.
LIST OF PERSONNEL

Tandem Accelerator Complex
A. Uedono

Director, Professor

K. Sasa

Associate Professor

D. Sekiba

Lecturer

T. Moriguchi

Assistant Professor

Y. Tajima

Mechanical Engineer

S. Ishii

Mechanical Engineer

T. Takahashi

Electrical Engineer

Y. YamatoElectrical Engineer

M. Matsumura

Technical Staff

S. Kuramochi

Administrative Staff

K. Iwase

Administrative Staff

H. Muromachi

Administrative Staff

Research Members1
Department of Physics
A. Ozawa

K. Sasa

T. Moriguchi

T. Yamaguchi (Saitama University [Cross appointment])
Department of Applied Physics
A. Uedono

H. Yanagihara

H. Tanimoto

S. Tomita

D. Sekiba

S. Sharmin

E. Kita

Department of Geoscience
M. Kurosawa
Department of Biology
I. Suzuki
Department of Chemistry
K. Sueki

A. Sakaguchi

Department of Information and Systems
T. Kameda

1

The “research members” include the authors and coauthors within 5 years back from this fiscal year, as well as themembers of research projects running at UTTAC.
58

Staff of Open Advanced Facilities Initiative
H. KudoH. Naramoto

M. SatakaK. Awazu (National Institute of Advanced Industrial Science and Technology [AIST])S. Aoki (Comprehensive Research Organization for Science and Society [CROSS])
Graduate students
Y. Sugisawa

K. Tomita

N. Kaname

S. Yamada

D. Hirose

N. Kishi

K. Nishizuka

Y. GaoZ. ShiD. Shiine

T. Yang

T. Ikeda

M. Inoue

R. Yaguchi

F. Higashi

M. Hayashi

A. YanoA. Taira

S. Hatada

T. Okamoto

T. Nakamura

Undergraduates
G. Kawasaki

External users and collaborators
Y. Iwata

National Institute of Advanced Industrial Science and Technology (AIST)

K. Tomita

National Institute of Advanced Industrial Science and Technology (AIST)

S. Shiki

National Institute of Advanced Industrial Science and Technology (AIST)

T. Ishizuka

National Institute of Advanced Industrial Science and Technology (AIST)

T. Matsunaka

Kanazawa University

M. Mihara

Osaka University

Y. Otani

Osaka University

Y. Kimura

Osaka University

H. Ishiyama

RIKEN

S. Matsumoto

Kyoto University, RIKEN

A. Sakaue

RIKEN

K. Itahashi

RIKEN

T. Uesaka

RIKEN

J. Zenihiro

Kyoto University

K. Yako

University of Tokyo

R. Sekiya

Kyoto University, RIKEN

R. Tsuji

Kyoto University

Y. Shiina

Rikkyo University

F. Miyake

Nagoya University

K. Kanzawa

Nagoya University

59