J-PARC
ANNUALREPORT2 O 2 1
Vol.2: Materials and Life Science
Experimental Facility

MLF
ANNUALREPORTCover photographs
Neutron diffraction experiment under high temperature tension.
A metal sample is heated by the halogen lamps from the top andbottom in the photo, and tensile loading is applied horizontally to themetal sample.

Inside the laser amplifier excitation module, which can irradiate a totalof 18 kW of excitation light from three directions to the laser crystal
positioned in the center of the photo.
The high-intensity vacuum ultraviolet light produced from the laser
beam amplified here is used to generate Ultra-Slow Muons.
Spectrometer for high-field muon spin relaxation/rotation/resonance
up to 5 Tesla at the S-line, with 3008 scintillation fibers to detect muon
decay positrons.

Materials and Life Science Division
J-PARC Center
https://mlfinfo.jp/en
J-PARC was jointly constructed and is now operated by the High Energy Accelerator
Research Organization (KEK) and the Japan Atomic Energy Agency (JAEA).

Comprehensive Research Organization for Science and Society
https://neutron.cross.or.jp/en

J-PARC 22-02

MLF Annual Report 2021

Preface

PrefaceToshiya Otomo

Division Head of Materials and Life Science Division, MLF
The proton power ramp up and instrument upgrades at the MLF were still progressing under COVID-19. Although we had to comply with the COVID-19 restrictions, the neutron and muon beams were supplied as usual. The
beam power of the MLF was ramped up to 700 kW from 600 kW in April 2021 and the availability at 700 kW was morethan 90%. The MLF received 740 kW during the MR operation period with slow extraction mode, which is the highest power ever attained for the long-term user operation at the MLF. With the increase of the beam power, it became
more important to perform radiation prevention works and maintenance of the targets safely and on schedule. From
this point of view, a long enough summer maintenance period was secured to allow the MLF and the J-PARC management to check carefully the progress, which led to the late start of the user operation in January 2022. The summer
maintenance of 2021 was finished safely on schedule.
Progress was made in the development of neutron instruments, such as the low-temperature Digital image correlation technique for hybrid neutron diffraction (BL19), completion of the polarization system of the Polarized Neutron
Spectrometer (BL23), noise reduction method based on deep learning which can shorten measurement time to one
tenth of the conventional neutron reflectometry measurement on BL17, H2O/D2O vapors supply system, New 2D scintillator detectors for a single crystal diffractometer (BL18) and Fe/Ge polarizing supermirror with m = 6.2 (the highest
achieved in the world).
In the muon H line, the on-beam commissioning performed since the first beam delivery in January 2022 wascompleted successfully, and the S-type experiment (DeeMe; an approved proposal for conducting a muon-electron
conversion experiment at J-PARC MLF. http://deeme.phys.sci.osaka-u.ac.jp). The initial analysis of the samples returned
by Hayabusa-2 was performed using a non-destructive elemental analysis method with negative muon capture characteristic X-rays at the D-line.
We initiated a series of internal group discussions to establish MLF’s future plans, “MLF2030”, based on the existing
instruments and devices. This plan is expected to be connected with or to improve the plan of target station 2 of the
MLF.
The users’ visits from abroad were significantly limited by the COVID-19 restrictions. Many proposals were carriedout and some of them were conducted by beamline scientists without user’s visit. To implement these carried-out
proposals, the 2020B term was shortened and the call for proposals was combined into a single term of 2020B and
2021A. On the other hand, several workshops were held online, such as the target system workshop with SNS of Oak
Ridge National Laboratory, the18th Korea-Japan meeting on neutron science hosted by JSNS (The Japanese Society
for Neutron Science), J-PARC MLF and KNBUA (The Korean Neutron Beam Users Association), the Annual meeting ofindustrial application at J-PARC MLF with 352 participants, including 150 attendees from companies, collaborative scientific and technical series of workshops with the Australian Nuclear Science and Technology Organization (ANSTO),
the 5th Neutron and Muon School (NM-school) was held as KEK-IINAS (Inter-Institution Network for Accelerator
Science) School for both lectures and remote hands-on (https://mlfinfo.jp/sp/school/5th-nms/index.html).
In conjunction with the reopening of the neutron user program at Japan Research Reactor - 3 (JRR-3), J-JOIN wasformed by JAEA, KEK, CROSS, the University of Tokyo, and Ibaraki Prefecture in 2021. A portal site of J-JOIN has been
opened, which provides one-stop consultation for neutron and muon use to support users not familiar with that field,
and allow them to gain the expertise to access the neutron and muon experiments.
Although the user program at MLF was severely affected by the pandemic, we managed to continue it thanks
to the efforts of the MLF staff and the understanding of the MLF users. I believe that the MLF will continue to deliver
cutting-edge science and more opportunities for its users under these difficult circumstances.
Materials and Life Science Division, Japan Proton Accelerator Research Complex
https://mlfinfo.jp/enPreface

MLF Annual Report 2021

Preface

Mitsuhiro Shibayama

Director, CROSSThe Comprehensive Research Organization for Science and Society (CROSS), a partner institution of the Materials
and Life Science Experimental Facility (MLF), is honored to release the J-PARC MLF ANNUAL REPORT 2021 (MLF-AR2021),
which includes sections on R&D Highlights, Neutron Sources, Neutron Science, Muon Science and more. CROSS is a
registered organization of the J-PARC's Specific Neutron Beamline Facility, appointed by the Japanese government in2011. CROSS supports the activities of the 7 public beamlines of MLF (BL01 4SEASONS, BL02 DNA, BL11 PLANET, BL15TAIKAN, BL17 SHARAKU, BL18 SENJU, and BL22 RADEN) and provides high-quality user support to MLF users, bothacademic and industrial researchers, and promotes the use of the facility.
In FY2021, the neutron beam at MLF was stably operated mostly at 600 – 700 kW, which ensured highly reliablemachine operation. In FY2020, due to the COVID-19 pandemic, it was necessary to merge the 2020B and 2021A terms
and expand the proposal round to 2020B + 2021A. Therefore, the statistics provided in this volume, i.e., MLF-AR2021,
is exclusively for 2021B. The total numbers of (short term) neutron proposals submitted and accepted in the term of
2021B were 343 and 142, respectively, and those for the Public Beamlines were 162 and 59, respectively. Regarding theoutcome, 193 scientific papers (excluding proceedings) were published from the MLF in 2021, 72 of which were fromthe Public Beamlines. The details are included in the Research and Development Highlights collected in this volume.
The numbers of press releases were 21 from the MLF and 8 from the Public Beamlines. These numbers illustrate thehigh activities of the Public Beamlines as well as the MLF, which have been used by a wide range of users from the academia and various industries. The special program for new users “New User Promotion (NUP)”, which started in 2016,
was operated also in 2021, and 9 NUP neutron users conducted experiments at the MLF.
Regarding public relations, in FY2020, a unified consultation service for the J-PARC MLF, “J-PARC JOIN” was operated by the J-PARC MLF, Ibaraki Prefecture, and CROSS. In FY2021, J-PARC JOIN was renamed “J-JOIN” and the service
was strengthened because JRR-3 (JAEA and the University of Tokyo) joined in this service program (https://jrr3ring.
jaea.go.jp/jjoin/index_en.php).
I hope this Annual Report would provide useful information about the current status of the MLF operations andrecent scientific achievements, the technical R&D reports, and so on. On behalf of CROSS, I sincerely welcome your visit
to the MLF.

Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society
https://neutron.cross.or.jp/en

Contents
PrefaceOrganization Chart
J-PARC Map
Muon and Neutron Instruments

Research and Development Highlights
Visualization of Local Structure around Boron in SiC Using Neutron Holography······································································

2

From Translucent Liquid to Black Solid: The Irreversible Transformation of CS2 under pressure···········································

4

Development of Spin-Contrast-Variation Neutron Powder Diffractometry for Extracting the Structure Factor of
Hydrogen Atoms···························································································································································································

6

Strengthening Contributions of CrFeCoNi High-Entropy Alloy at Low Temperatures: Insights into Multiple
Deformation Mechanisms by In Situ Neutron Diffraction··············································································································

8

Residual Stress in Steel Bars Processed by Cold Drawing and Straightening··············································································· 11
Hydrogen Storage by Earth-Abundant Metals········································································································································· 14
Liquid Structure in Superconcentrated Electrolytes for Next Generation Aqueous Li ion Batteries···································· 17
Distinguishing Adsorbed and Deposited Ionomers in the Catalyst Layer of Polymer Electrolyte Fuel Cells Using
Contrast-Variation Small-Angle Neutron Scattering························································································································ 20
Evaluation of Interfacial Water between Polypropylene and Si Substrate····················································································· 23
Conformational Dynamics of a Multi-Domain Protein by Neutron Scattering and Computational Analysis··················· 26
Spin Texture Induced by Non-Magnetic Impurity in the Triangular Lattice Antiferromagnet h-Y(Mn,Al)O3····················· 29
Duality of Magnetic Excitations and Kondo Effect in Metallic Ferromagnet Fe3-xGeTe2···························································· 31
Nontrivial Temperature Dependence of Magnetic Anisotropy in Multiferroics Ba2MnGe2O7················································· 34
Study of a Low Temperature Crystal Structure of a New Magnetoelectric Material··································································· 37
Crystalline Electric Field in Non-Centrosymmetric CeTX3···················································································································· 40
Spin Dynamics of the Dual Isolated Antiferromagnetic System Ba2CoTeO6·················································································· 42
Magnetic Excitations in Chiral-Structure Phase of Ce3Ir4Sn13·············································································································· 45
Two-Dimensional Ferromagnetism at Topological Surface of FeSi Observed by Polarized Neutron Reflectometry····· 48
Ferromagnetic Hysteresis Induced by Vortices in a Magnetic Superconductor EuRbFe4As4··················································· 50
Muon-Induced Soft Errors in 20-nm SRAMs: Similarities and Differences with Neutrons and Alpha Particles················ 52
Li Diffusion Studied by QENS with Single Crystal···································································································································· 54
Visualization of Generated Water in Newly-designed Polymer Electrolyte Fuel Cell during Power Generation·············· 56
Molecular Motion Improves Solar Cell Performance: a Muon Spin Relaxation Study······························································· 59
High Resolution Spectroscopy of Electronic K X Rays from Muonic Atoms·················································································· 62
Rabi-Oscillation Spectroscopy for Precise Measurement of Hyperfine Structure of Muonium Atom································· 65
Measurements of the Neutron Capture Cross Section of 243Am around 23.5 keV······································································· 67
Wide Bandwidth Neutron-Spin Polarizer Due to Ferromagnetic Interlayer Exchange Coupling·········································· 70

Neutron Source
Neutron Source Section···················································································································································································· 74
Optimization of Mercury Target Vessel Design to Extend the Lifetime by Using Machine Learning··································· 76
Radiation Safety Countermeasures for Pump Replacement of the Off-gas Processing System············································ 78

Neutron Science
Neutron Science Section·················································································································································································· 82
BL01: 4D-Space Access Neutron Spectrometer 4SEASONS················································································································· 84
Current Status of BL02 DNA in 2021····························································································································································· 86
IBARAKI Biological Crystal Diffractometer iBIX········································································································································· 88
Development of a LaBr3(Ce) Scintillator System for Detecting Prompt Gamma Rays at ANNRI············································ 90
Status of Fundamental Physics Beamline BL05 (NOP) in 2021··········································································································· 92
BL06: Commissioning Status of Village of Neutron Resonance Spin Echo Spectrometers (VIN ROSE)······························· 95
BL08: Verification of Sample Temperatures Using a High-Temperature Sample Stick for Cryofurnace······························· 97
BL10: NOBORU····································································································································································································· 100
Recent Developments at BL11 PLANET······················································································································································ 102
High Resolution Chopper Spectrometer HRC·········································································································································· 104
BL14 AMATERAS·································································································································································································· 106
Upgrading TAIKAN······························································································································································································ 108
Renewal of Optical Components for Multi Incident-angle Neutron Reflectometry··································································· 109
Current Status of SHARAKU: Polarized Neutron Reflectometer········································································································· 112
Status of SENJU 2021························································································································································································· 114
Engineering Material Diffractometer TAKUMI·········································································································································· 116
The Current Status of the Versatile Neutron Diffractometer, iMATERIA·························································································· 118
Status of the High Intensity Total Diffractometer (BL21, NOVA)········································································································ 120
Current Status of the Energy-Resolved Neutron Imaging System RADEN····················································································· 122
Polarized Neutron Spectrometer POLANO················································································································································ 124
Sample Environment at the MLF··································································································································································· 127
Development of Circuit Boards for Optical/Electrical Conversion···································································································· 129
Activities for Remote Access at MLF····························································································································································· 131

Muon Science
Muon Section Overview··················································································································································································· 136
Present Status of the Muon-Beam Source················································································································································· 138
Beam Commissioning at D1/2 Areas···························································································································································· 140
Current Status of µSR Experiment at D1····················································································································································· 143
Development of D2 (Muonic X-ray Element Analysis) Instrument and Sample Environment··············································· 145
Beamline Magnets and Power Supplies Replacement of DB2 Coils and Status of Updating the MPS program for
the Muon Target···························································································································································································· 147
Commissioning of the Ultra-slow Muon Beamline in FY2021············································································································ 151
USM Commissioning at U1B area [J-PARC: 2021B0001]························································································································ 153
The Progress of Laser System for Ultra-Slow Muon Generation········································································································ 155
Present Status of the S-line·············································································································································································· 157
Development of Sample Environment at the S1 Area − Reorganization of Electrical Systems −·········································· 158
H-Line Commissioning······················································································································································································ 160

MLF Safety
Research Safety···································································································································································································· 164

MLF Operations in 2021
Beam Operation Status at the MLF······························································································································································· 168
Users at the MLF·································································································································································································· 170
MLF Proposals Summary – FY2021······························································································································································· 171
MLF Division Staff 2021····················································································································································································· 173
CROSS Staff 2021································································································································································································· 176
Ibaraki Neutron Beamline Staff in 2021······················································································································································ 178
Proposals Review System, Committees and Meetings·························································································································· 179
Workshops, Conferences, Seminars and Schools in 2021···················································································································· 183
Award List·············································································································································································································· 186
MLF Publication 2021························································································································································································ 187
Editorial Board - MLF Annual Report 2021················································································································································· 199

Organization Chart

MLF Annual Report 2021

Organization Chart

MLF Annual Report 2021

J-PARC Map

J-PARC MAP
CROSS(Ibaraki Quantum Beam Research Center)

J-PARC Center Users Oﬃce

R245

(

KEK Tokai Campus

Main Gate
R245
Linac

HENDEL R&D Building

3 GeV Synchrotron

MLF

50 GeV Synchrotron

J-PARC Research Building

J-PARC Map

S1

S2

25 m

1m

As of March 2022

MLF Annual Report 2021

400 ｍmH LineMuon and Neutron Instruments

Research and Development
Highlights

Research and Development Highlights

MLF Annual Report 2021

Visualization of Local Structure around Boron in SiC Using
Neutron Holography
1. Introduction
One of the basic technologies that support the infrastructure of modern society is the development ofvarious devices using semiconductors. Silicon is still
the main semiconductor material, but in order to meetthe needs for higher power and high-speed communication, it is necessary to develop power devices thatcan efficiently control and convert power without loss.
Silicon carbide (SiC) crystals are a leading candidate for
this, and the competition to fabricate high-quality SiC
wafers is intensifying in the world [1]. However, the crystal structure of the SiC is not as simple as silicon. SiC
exhibits polymorphism, and we chose 6H-SiC among
various polytypes. The 6h-SiC has six different crystal sites, while Si has one crystal site. In order to havefunctionality for these semiconductors, it is necessary
to dope some impurities (dopants). Among various dopant elements for SiC, boron is used for white LEDs. It is
predicted that the properties of SiC are varied depending on which crystal sites boron atoms locate. Therefore,
unlike Si, it is important to control the dopant sites, anda more advanced crystal growth technology is required
to realize this. However, for light element dopants suchas boron and nitrogen, there had been no appropriate
observation method of their local structures. Therefore,
no one has known the exact locations of boron in SIC.
On the other hand, since 1998 we have developed
X-ray fluorescence holography, which provides 3D atomic
images around fluorescing atoms. And we have applied it
to local structure analyses around dopants of many functional materials [2]. In addition, we started neutron holography in 2008, and we demonstrated successfully themultiple wavelength neutron holography using time-offlight (TOF) technique at J-PARC in 2017 [3]. This technique uses prompt γ-rays from neutron-absorbed nuclei,
like X-ray fluorescence in X-ray fluorescence holography.
Therefore, neutron holography (NH) would be suitable
for the investigation of the local structure around theγ-ray emitter atoms. The significant advantage of neutron holography is recording a number (50~100) of
multiple-wavelength neutron holograms, which cansubstantially suppress ghost images. We applied neutron
holography to B: MgSi2 [4], and Sm: RB6 (R = Yb, La) [5].
In the present study, we measured neutron holograms of B-doped 6H–SiC by the time-of-flight (TOF)
technique and estimated the occupancies of six different
2sites from the reconstructed atomic images [6].
2. Experimental details
A B-doped 6H–SiC single crystal was grown by thephysical vapor transport method known as the seeded
sublimation process. As source materials, SiC powder
was synthesized from elemental silicon and carbon
with an addition of 0.065 at.% of B. The amount of doping was chosen so as to reach a chemical dopant incorporation of ca. 2 × 1019 cm–3. The growth temperature
was 2150°C, determined with an optical pyrometer on
the top growth cell, which corresponded to ca. 2200°C
at the growth interface. The total crystal height in thecenter of the boule was 29 mm. From this single crystal,a measurement sample with a diameter of 20.1 mm anda height of 15.2 – 21.4 mm was prepared by wire-sawing
and grinding.
The NH experiment was performed at beamline 10(BL10). The measurement was carried out in the “inverse
mode,” and the angular anisotropy of the sample orientation was measured from the intensity of prompt γ rays,
which were mostly emitted from B. The γ-rays were detected by Bi4Ge3O12 (BGO) detector with a diameter of
6 cm. The BGO detector was covered by Pb blocks to
reduce the γ-ray background.
A hologram is obtained by normalizing the angularanisotropy with respect to its background. We recorded ~100 different wavelength holograms in one scan.
Figure 1 shows the hologram at λ = 0.49 Å.

Figure 1.	Neutron hologram of B-doped 6H-SiC. The wavelength is 0.49 Å.

MLF Annual Report 2021

3. Results and discussion
By applying the Barton algorithm [7], which likes
to Fourier transformation, to the multiple-wavelength
neutron hologram, the atomic image around the boron
could be obtained as shown in Fig. 2. Boron is present
at the origin. Many atomic images are observed below
the boron, but none above. This result suggests that aboundary exists just above the boron.
Next, the sites occupied by boron were determinedusing the atomic images in the lower region of Fig. 2. As
mentioned above, there are 6 different sites in boron,such as Si-h, Si-c1, Si-c2, C-h, C-c1, and C-c2 (see Fig. 3).
The patterns of atomic images obtained from the calculated holograms with different boron sites are different.
If boron was doped only at a single site, we can determine it smoothly. But the situation was not so simple.
Therefore, we assumed that the boron atoms occupied multiple sites, and calculated the site occupancy
using a calculation method called the steepest descentmethod. As a result, it was found that 37.5% of the boron atoms were located on Si-c2 and 61.4% on C-c2,
and they hardly go to other sites. We performed sucha quantitative determination of boron locations in SiC
for the first time.
Figure 3 shows a model diagram of the boron
neighborhood created by combining the above results.
The sites of Si-c2 and C-c2 are next to each other, and it
is conceivable that boron is enriched there. In addition,
the concentrated boron may act in forming an above
boundary. The reason of the right above is related to the
SiC crystal growth method. Most crystals, such as silicon,
are grown by solidifying from a melt, but SiC crystals areusually grown by a physical vapor deposition, in which
Si and C atoms are stacked from the bottom to the top.
Therefore, the boundary would be formed when siliconor carbon are deposited directly on the boron at Si-c2
and C-c2. Such an incomplete structure may not necessarily be desirable in terms of SiC quality. However, we
believe that such a discovery becomes a starting point
and that the findings of this study can be applied to future SiC wafer development.
4. Perspective
Demands of power devices, which can operate with
better energy efficiency, are rapidly increasing in highspeed communications, such as 5G and power controlof electric vehicles.

Research and Development Highlights

Figure 2. Images of the (112–0) plane.

Figure 3.	A possible model of the environmental structurearound B.

SiC is the only material that has been put to practical use, and the control and observation of dopantsthat bring functionality as semiconductors is the mostimportant issue. The material is directly related to the
future social infrastructure, and the fact that we wereable to accurately determine the dopant structure by
neutron holography this time is considered to have agreat social impact.
References[1] P. J. Wellmann, Semicond. Sci. Technol. 33, 103001(2018).
[2] K. Hayashi and P. Korecki, J. Phys. Soc. Jpn. 87, 061003(2018).
[3] K. Hayashi et al, Sci. Adv. 3, e1700294 (2017).
[4] W. Saito et al., ACS Appl. Energy Mater. 4, 5123 (2021).
[5] S. Uechi, et al., N Phys. Rev. B 102, 054104 (2020).
[6] K. Hayashi, et al., Appl. Phys. Lett. 120, 132101 (2022).
[7] J. J. Barton, Phys. Rev. Lett. 67, 3106 (1991).

K. Hayashi1, K. Ohoyama2, and P. Wellmann3
Nagoya Institute of Technology; 2Ibaraki University; 3Friedrich-Alexander Universität Erlangen-Nürnberg (FAU)

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MLF Annual Report 2021

From Translucent Liquid to Black Solid: The Irreversible
Transformation of CS2 under pressure
1. Introduction
Carbon disulfide (CS2) is a translucent liquid madeof linear S = C = S molecules. Under strong compression
in the multi-GPa range, such molecules are expected todisintegrate as the C = S double-bonds break up leading
to an extended solid with very different structural andelectronic properties. This was indeed observed for CS2
several decades ago [1], but despite a number of later
experiments mainly carried out using diamond anvil
cells [2], the nature of the transition and the propertiesof the final product are ill-known.
At BL11, we carried out the first in-situ high pressure
neutron measurements of this famous transformation.
These experiments allowed to demonstrate the possibility to recover the high-pressure product to ambientpressure and establish a recipe for mass-production of
the compound in off-line compression runs. The availability of such large quantities of material at ambientpressure enables an in-depth characterization by advanced analytical methods which were not possible
before [3].

2. Experimental
High pressure measurements were carried out at
BL11 PLANET at 300 K using a Paris-Edinburgh high pressure cell (MG63, VX4) equipped with sintered diamondanvils. The pressure of the sample was determined fromthe load on the anvils and a previously established calibration curve.
3. Results and discussion
The compression of the liquid sample leads firstto its crystallization into the known orthorhombic
Cmca structure at ~1.5 GPa (Fig. 1). When the sample
is then further compressed, a sudden transition occurs
at ~8 GPa which leads to a complete loss of all Braggreflections and hence to a non-crystalline material. Data
collected under decompression (Fig. 1) shows that the
sample can be recovered to ambient pressure without
further changes of its structure and extracted from thepressure cell (Fig. 2) where the black solid material isstable over a time-scale of at least months. Laboratory
analyses by Raman spectroscopy and densitometry

Figure 1.	Neutron diffraction patterns of CS2 under pressure, collected at
BL11. At low pressures, the liquid crystallizes in an orthorhombic
Cmca structure (a Rietveld fit and difference curve are shownfor the 3.6 GPa pattern). At 8.0 GPa, the system transforms toa non-crystalline solid, which can be recovered to 0 GPa (Reprinted from Ref. [3] with permission from Elsevier).

4

MLF Annual Report 2021

Research and Development Highlights

Figure 2.	Picture of a sample (black sphere inside the metallic gasket) after compression of CS2 to 8 GPa
and subsequent pressure release.

carried out in the home institute of the PI showed thatthe recovered material is a mixture of crystalline sulfur
and a compound with composition C2S. Subsequent
neutron diffraction measurements carried out also at
BL11 in a vanadium can showed that C2S has a graphitic
structure with sp2-bonded carbon flakes of nanometricsize (typically 3 nm diameter). A similar analysis using
X-ray diffraction (which is more sensitive to sulfur atoms)
confirms the presence of sulfur and suggests bonding to
the graphitic matrix through both covalent C-S and vander Waals bonds. Scanning and transmission electron
microscopy also confirms the average stoichiometry as
C2S but reveals a significant scatter in the C/S ratio depending on the selected grain of the powder. The sample was also investigated by resistivity measurements in
the 4–300 K range. C2S is a semiconductor with a small
gap of 45 meV, and its electrical conductivity can be
described by a variable-range hopping model with thedimensional parameter d = 1.3 [4]. Finally, it was foundby gravimetric measurements that the sulfur content
can be reduced by heating the sample to beyond 200°C
where the van der Waals bonded fraction of sulfur detaches from the carbon matrix. This leaves only the covalently bonded sulfur in the sample and results in an
average stoichiometry of CxS (x~10) above ~ 300°C.
The overall conclusion of these experiments is thatthe compound synthesized by compression of liquid
CS2 in a large-volume press (such as the Paris-Edinburghcell) is significantly different from the apparently polymeric material obtained by compression in diamondanvils cells, commonly called “Bridgman black” [2]. The
reason is most likely the following: Carbon disulfide iseven at ambient conditions a metastable molecule since
it has a positive formation enthalpy, i.e. the decomposition into its elements is exothermic. When CS2 is hencecompressed to a few GPa, it first transforms into polymeric Bridgman black, which still contains unsaturated
C = S bonds. In a large-volume press, the reaction heatcannot be extracted rapidly and the sample heats further and is fully transformed into more stable constituents, i.e. a mixture of sulfur and C2S. Hence, Bridgman
black appears simply as an intermediate state between
molecular CS2 and the stable reaction products S andCxS (x = 2–10).
4. Future plans
It would be interesting to confirm the structuralmodel we have proposed, i.e. the exact location of sulfur in the graphitic matrix, by other methods. It might
be possible with more advanced electron microscopy.
We note that the CxS type compounds discovered in thiswork could be an interesting candidate for a cathodematerial in Li-S batteries [5].
References[1] P.W. Bridgman, Proc. Am. Acad. Arts Sci. 74 399(1942).
[2] B. Ochiai & T. Endo, Prog. Polym. Sci. 30, 183 (2005).
[3] S. Klotz, T. Hattori, B. Baptiste, S.M. Feng, Ch. Jin, K.
Béneut, J.M. Guigner, I. Estève., Carbon 185, 491(2021).
[4] N.F. Mott, Phil. Mag. 19, 835 (1969).
[5] S. Zheng, Y. Wen, Y. Zhu, Z. Han, J. Wang, J.Yang, C.
Wang. Adv. Energy Mat. 4, 1400482 (2014).

S. Klotz1, B. Baptiste1, T. Hattori2, S. M. Feng3, Ch. Jin3, K. Béneut1, J.M. Guigner1, and I. Estève1
IMPMC, Sorbonne University, Paris, France; 2Neutron Science Section, Materials and Life Science Division, J-PARC Center; 3Institute ofPhysics, Chinese Academy of Science, Beijing, China

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Research and Development Highlights

MLF Annual Report 2021

Development of Spin-Contrast-Variation Neutron Powder
Diffractometry for Extracting the Structure Factor of
Hydrogen Atoms
1. Introduction
The coherent polarized neutron scattering lengthof hydrogen, bH, varies according to the proton spin polarization PH with respect to the neutron spin direction,

succeeded DNP of crystalline samples by impregnating
milled microcrystals into TEMPO-doped dispersion media. These microcrystals are polarized via spin diffusionfrom the dynamically polarized media. We used the new
DNP technique to SCV-NPD.

bH = bH0 + ∆bHPH, 			(1)with bH0 = −3.74 fm and ∆bH = 14.56 fm. Thus, the scattering curves of the neutron against hydrogen-containing
materials remarkably vary as a function of PH. Spin contrast variation (SCV) is a technique to determine structure of materials by the analysis of the PH-dependent
multiple scattering curves. SCV has been used with smallangle scattering and reflectivity for nano-structure analyses of composite materials [1] and multi-layer films [2],respectively.
SCV neutron diffraction (NPD) can be used to determine positions of hydrogen atoms in crystalline samples(Fig. 1) [3]. However, SCV has been underused in diffractometry to date because the polarization technique isseverely limited when applied to crystalline samples.
In SCV, the sample is hyperpolarized by dynamic nuclear polarization (DNP), which transfers polarizationfrom electron spins to proton spins using microwaves
with a frequency close to electron paramagnetic resonance. Here, doping of free radicals suited for DNP such
as 2,2,6,6,-tetramethyl-1-piperidinyloxy (TEMPO) is essential for DNP. However, it is impossible to dope theseradicals into most of crystalline samples.
Meanwhile, Rossini et al. [4] and Miura et al. [5]2. Experiment
The samples comprised β phase L-glutamic acid
(LGA) powder dispersed in deuterated polystyrene containing 25 mM of 4-methacryloyloxy-TEMPO (TEMPO
methacrylate). The four sheets of the samples with a
total thickness of approximately 3 mm were stacked
and set in the sample cell of the DNP apparatus, whichpolarized the sample by irradiating 94 GHz microwave
at 3.3 T and 1.2 K [6]. The opening angle of the neutron
window was so small that the DNP apparatus was rotated by 19° from the direction of the incident neutrons to cover values of the scattering angle 2θ in theranges of 14–27° and 144–159° with the middle-angle
and backward detectors, respectively. Although theoverall range of 2θ was severely limited, time-of-flightmeasurement with neutron wavelength λ from 1.6 to
7.5 Å offered seamless cover of the magnitude of thescattering vector Q from 0.4 to 1.6 Å−1 and from 1.6 to
7.5 Å−1 with the middle-angle and backward detectors,
respectively. The scattering from a positively polarized
sample, a negatively polarized one, and an unpolarized
one was accumulated for 5 h in each case. The incoherent scattering of the sample, the coherent scattering of
the deuterated polystyrene, and the scattering of the air
were subtracted from those data.
3. Result and Discussion
Figure 2 shows the SCV-NPD data in the range 1.2 ≤Q ≤ 2.6 Å−1. The intensities of the peaks at Q = 1.27 and1.46 Å−1 decrease with increasing PH, whereas those at
Q = 1.43 and 1.58 Å−1 increase, and the intensity at Q =1.53 Å −1 is unchanged with PH.
Intensity of each peak I(Q, PH) is given by
I(Q, PH) = {m(Q)/Q2} |F(Q, PH)|2.		

Figure 1. (a) Conventional NPD measures all elements (redspheres), but (b) SCV-NPD detects only hydrogen(red spheres) [3].

6(2)Here, m(Q) is the multiplicity, and F(Q, PH) the structure
factor, which is rewritten using the factors of hydrogenMLF Annual Report 2021

Research and Development Highlights

atoms at PH = 0% FH(Q) and the other elements (C, N, andO in this case) Fothers(Q) as
F(Q, PH) = (1 − κPH)FH(Q) + Fothers(Q)		

(3)

with κ = |∆bH/bH0|. Note that the polarization dependence of the coherent scattering lengths for these otherelements are negligible compared to hydrogen. From
Eqs. (2) and (3), the self-correlation term of hydrogen atoms|FH(Q)|2 and the cross-correlation term Re[FH(Q)Fothers(Q)*]are obtained from the equations,
H)

( ,

and

{

1
2

( ,

( )
2

( ,

2(

H)

H)

H)
2

( ,

H

( ,0)

H)

−

( )

=

( ,

2

H)

[ H ( ) others ( )∗ ].

(| H ( )|2
( ,

H)
2
H)

Figure 2.	(a) SCV-NPD data (b) Calculated intensities of thepeaks at PH = −16% (Top), 0% (Middle), and +16%
(bottom) [3].

(4)

( ,0)

}=

(5)

The data shown by the blue single-line graph in Fig. 3
were obtained by substituting the intensities at PH = 0
and ±16% in Fig. 3 into I(Q,0) and I(Q,±PH) in the left sidesof Eqs. (4) and (5). Meanwhile, the orange filled-line
graph is of calculated (m(Q)/Q2)|FH(Q)|2 and (m(Q)/Q2)
Re[FH(Q)Fothers(Q)*] in the right sides of the equations,which are broadened using the Q-resolving power of
TAIKAN. As shown in Fig. 3, the experimental data reproduce the calculated peaks.
4. Future plans
We are now developing a 6.7 T DNP apparatus withwider neutron windows for improved proton polarization, Q range, and neutron count rates. Measuring at
higher proton polarization would give greater differences in peak intensities between different spin configurations, and improved neutron count rates would
provide statistical significance in the analysis. We arealso developing a dry hydrogel with a volume filling
ratio of only 2% as a dispersion media to decrease thebroad diffraction peaks which overlap with peaks of
crystalline domains [7]. Very recently, Okudaira et al. [8]advanced further the development of a 3He neutron

Figure 3.	Blue single-line graphs of (a) (m(Q)/Q2)|FH(Q)|2, and(b) (m(Q)/Q2)Re[FH(Q)Fothers(Q)*] obtained by substituting the experimental data into Eqs. (4) and(5). Orange filled-line graphs are calculated with thepeaks broadened by the resolving power of TAIKAN [3].

polarizer, which polarizes neutrons with λ smaller than
1.6 Å. The SCV-NPD technique will be used much moreby installing the 3He polarizer in many diffraction beamlines in near future.
References[1] W. Knop et al., J. Appl. Cryst. 25, 155 (1992).
[2] T. Kumada et al., J. Appl. Cryst. 52, 1054 (2019).
[3] D. Miura et al., J. Appl. Cryst. 54, 454 (2021).
[4] A. Rossini et al., J. Am. Chem. Soc. 134, 16899 (2012).
[5] D. Miura et al., Prog. Theor. Exp. Phys. 033D01 (2019).
[6] T. Kumada et al., Physica B 404, 2637 (2009).
[7] Y. Sekine et al., ACS Appl. Polym. Mater, 2, 5482
(2020).
[8] T. Okudaira et al., Nucl. Instrum. Methods. Phys. Res.
A, 977, 164301 (2020).

D. Miura1,2, 3, T. Kumada2,4, Y. Sekine2, T. Oku4, S. Takata5, K. Hiroi5, and T. Iwata1
Faculty of Science, Yamagata University; 2Materials Sciences Research Center, JAEA; 3Research Fellowship for Young Scientists of JSPS;
4
Technology Development Section, Materials and Life Science Division, J-PARC Center; 5Neutron Science Section, Materials and Life Science
Division, J-PARC Center

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Research and Development Highlights

MLF Annual Report 2021

Strengthening Contributions of CrFeCoNi High-Entropy
Alloy at Low Temperatures: Insights into Multiple
Deformation Mechanisms by In Situ Neutron Diffraction
1. Introduction
Unlike traditional alloys, high-entropy alloys (HEAs)
may maintain or improve their ductility under cryogenic
conditions [1–3]. Studying the high strength–ductility
combination in HEAs is of broad interest for industrial
applications at low temperatures but also for a better
understanding of their fundamentals. Space exploration
devices, superconducting magnets, and undergroundpower transmission cables are among the possible applications of strong and tough alloys under cryogenic
conditions.
The physics of HEAs has yet to be comprehended thoroughly. The occurrence of multiple deformation mechanisms has been associated with the abovementioned
improvement of ductility at low temperatures [2–5].
However, those mechanisms have not been well described
and the consequent strengthening contributions havenot been estimated at low temperatures. In situ tensileloading studies are necessary to pinpoint the microscopic origin of the extreme hardening and superior
ductility in HEAs. Neutron diffraction allows probing
bulk samples with millions of grains and simultaneous
analysis of dislocations, planar faults and phase transformation during deformation. In recent years, the development of sample environment capabilities at someneutron facilities enabled studying materials under extreme conditions. The TAKUMI beamline at the Materials
and Life Science Experimental Facility (MLF) of J-PARC
Center can perform in situ loading experiments at ultralow temperatures.
This work aimed at estimating the contribution ofdifferent strengthening mechanisms in a CrFeCoNi HEA
tested at four temperatures (25, 40, 140 K, and room
temperature) by in situ tensile measurements with neutron diffraction.
2. Experimental procedure
The equiatomic CrFeCoNi HEA alloys were prepared by arc-melting and suction-casting, followedby thermo-mechanical processing. The in situ neutron
diffraction deformation measurements were carriedout under tensile loading at the TAKUMI Engineering
Materials Diffractometer. The cryogenic loadingmachine equipped with a GM cooler was used for8

low-temperature experiments. The neutron diffraction
data were analyzed using Z-Rietveld and CMWP packages. More details about the experimental procedureand data analysis can be found in the original paper [6].
3. Results and discussion
The in situ neutron diffraction measurements werecarried out for CrFeCoNi HEA alloy under tensile loadingat 295 (RT), 140, 40 and 25 K. The stress-strain curves at
the four temperatures are shown in Fig. 1. Both strengthand ductility increased with decreasing the deformation
temperature. The diffraction data demonstrated asymmetrical peak broadening with decreasing the testing
temperature. Besides, the peak broadening becomes
massive and undergoes a significant shift in peak positions at low temperatures (Fig. 2). Those phenomena
indicated the occurrence of multiple deformation mechanisms, i.e., orientation-dependent profile broadening
due to dislocations, peak shift caused by stacking faults(SFs), and profile asymmetry because of deformation
twinning.
An orientation-dependent evolution of lattice strain
and texture was observed for the loading and the transverse directions from the in situ diffraction data. The
activation of different deformation mechanisms at low
temperatures, in addition to the dislocation slip, resulted
in the distinctive evolution of peak intensity, particularly

Figure 1.	Stress-strain curves of CrFeCoNi HEA at 295, 140, 40
and 25 K during in situ tensile experiments [6].

MLF Annual Report 2021

Research and Development Highlights

for (111)//LD, (200)//LD, (422)//LD, and (220)//TD. At low
temperatures, the texture for these orientations evolved
slowly due to the increasing role of twinning and/or limited role of dislocation slip, while at RT, there was a continuous increase when deformation was facilitated bydislocation slip alone. SFs caused the difference in thelattice strains of equivalent orientations (111) and (222)
as well as (200) and (400). The stacking fault probability(SFP) was determined from this difference in the latticestrain of equivalent orientations.
Regarding mechanical performance, the yield andtensile strengths increased by more than a factor of 2
with a significant increase in ductility (from 45 to 58.4%)
while decreasing temperature from RT to 25 K (Fig. 1).
The fractured sample at 25 K showed negligible necking
and thus sustained a more significant uniform elongation. The sample at 25 K also showed massive serrations.
The strain-hardening rate significantly increased at cryogenic conditions compared to the RT sample. The criticalstress for SF activation was temperature-independent,
and the SFs started at almost the same applied stressof 860 ± 20 MPa for all temperatures. Due to the higher

yield strength at low temperatures, the activation strains
for the SFs became lower with decreasing the temperature and SFP of 0.5%, 3.2%, and 4.7%, were achieved
at RT, 140 K, and 40 K/25 K, respectively, as is evident
from Fig. 3. Due to early activation and higher SFP,
the SFs played a prominent role in deformation at low
temperatures.
The dislocation density at 25 and 40 K was high andreached a similar value of ∼9.2 ×1015 m–2 at both temperatures (Fig. 3). The extremely high dislocation density is
the main reason for the outstanding strain hardening of
HEA at low temperatures. At low temperatures, the twin
fault probability (TFP) increased significantly, from 0.7%
at RT to 6% at 25 K (Fig. 3). As Fig. 3 shows, TFP at 40 K
was 5%, i.e., less than at 25 K. Given the similar SFP and
dislocation density at both 40 and 25 K, the difference
in TFP can be a possible cause of serrated deformation
at 25 K.
From the above results, the contributions of themain strengthening mechanisms were estimated, as
shown in Fig. 4. The grain boundaries and the initialdislocation density contributed ∼183 MPa towards the

Figure 2.	Evolution of peak profiles for (111) and (200) reflection with deformation at 295, 140 and 25 K [6]. The
peak shift, broadening and asymmetry are evident
as a function of progressive deformation strain atdifferent temperatures, which are signatures ofstacking faults, dislocations and twin faults, respectively.

Figure 3.	Evolution of dislocation density, twin fault probability and stacking fault probability with deformation
at 295, 140, 40 and 25 K. Adapted from [6].

9Research and Development Highlights

MLF Annual Report 2021

Figure 4.	Temperature-dependent strengthening contributions towards the yield stress and strain hardening.
Adapted from [6].

yield strength at all temperatures, while the Peierls
stress increased significantly at low temperatures andcontributed 148, 319, 454, and 493 MPa, at RT, 140, 40,
and 25 K, respectively. The dislocation strengthening
remained the major source of strain hardening at all
temperatures. However, the planar faults (stacking faults
and deformation twinning) contribution increased significantly from 40 MPa to 480 MPa, when the test temperature was lowered from RT to 25 K.

Acknowledgement
The in situ neutron diffraction experiments wereconducted at the TAKUMI beamline, under proposal
numbers 2016B0254, 2017B0142, and 2019A0180.
References[1] Gludovatz et al., Science, 345 1153 (2014).
[2] Laplanche, Acta Mater., 118 152 (2016).
[3] Naeem et al., Sci. Adv., 6 eaax4002 (2020).
[5] He et al., Nano Lett., 21 1419 (2021).
[6] Naeem et al., Acta Mater., 221 117371 (2021).

M. Naeem1, H. He1, S. Harjo2, T. Kawasaki2, W. Lin3, J.J. Kai3, Z. Wu4, S. Lan1,5, and X.L. Wang1,6
Department of Physics, City University of Hong Kong; 2Neutron Science Section, Materials and Life Science Division, J-PARC Center;3
Department of Mechanical Engineering, City University of Hong Kong; 4Center for Neutron Scattering and Applied Physics, City Universityof Hong Kong Dongguan Research Institute; 5Herbert Gleiter Institute of Nanoscience, Nanjing University of Science and Technology; 6City
University of Hong Kong Shenzhen Research Institute1

10MLF Annual Report 2021

Research and Development Highlights

Residual Stress in Steel Bars Processed by Cold Drawing
and Straightening
1. Introduction
Special steel bars with high machinability called
free-cutting steel are used for shafts and other parts
that are cut for use in precision instruments, electronicequipment, etc. Using wire rod as a raw material, it isformed into bars having a high degree of straightness
through complex plastic forming processes, such as cold
drawing, spinner straightening, and roll straightening.
On the other hand, subjecting a bar manufactured withgood accuracy to a cutting process generates bending and deformation in the bar material that can leadto problems, such as drops in the degree of roundness
and straightness. The cause of such bending and deformation is the release during machining of residual
stress accumulated within the raw material at the timeof plastic forming. Therefore, in the actual manufacturing process, a straightening process is used to reduce
the residual stresses generated in the cold-drawing
process. Determining the distribution of internal residual stress in products manufactured by plastic forming
plays an important role in achieving product accuracy
and reliability [1, 2]. The ability of neutron diffraction
to penetrate deep into the material makes it possible
to measure residual stress in the interior portion of thesteel material. The purpose of this study is to measure
the internal residual stress distribution in cold-drawn
and straightened free-cutting steel bars using the neutron diffraction technique, and to clarify the mechanismof residual stress generation and residual stress reduction by straightening using the finite element method.
2. Material
A low-carbon free-cutting steel bar (SUM24L type)with a diameter of 10 mm and a length of 2500 mm wasused. In the experiment, the bar material underwent a colddrawing process consisting of drawing, spinner straightening, and roll straightening. A schematic diagram of thisoverall cold-drawing process is shown in Fig. 1 [3]. The rods
were drawn in one pass from a 12 mm diameter to a final
diameter of 10 mm (31% reduction in section). After that,the lots were subjected to spinner and roll straightening,which are rotary bending straightening processes. Detailsof the experiment can be found in reference [3].
3. Experiment and results
To conduct the measurements, we used the J-PARC/
MLF BL19 “TAKUMI” diffractometer and measured theresidual strain at 11 locations in the direction from thematerial surface to the central axis at 0.5 mm intervals.
Additionally, each processing, we cut out 1.5 mm cubes
from the steel bar by electrical discharge processing
and assembled them with no directivity. We used thesecubes as strain-free standard samples for use in measuring d0. To measure strain in the hoop and radial directions, the incident beam slit was set to 1 mm × 30 mm
and the radial collimator width to 1 mm to form a

Figure 1.	Schematic of cold-drawing process.

11Research and Development Highlights

MLF Annual Report 2021

measurement region of 1 mm × 1 mm × 30 mm. To
measure in the axial direction, the incident beam slit
was set to 1 mm × 1 mm to form a measurement regionof 1 mm × 1 mm × 1 mm. To shorten the measurement
time of the neutrons, the measurement area was increased to 30 mm for axial measurements as the change
along the axis is considered to be small.
The results based on the d0 coupons for each process are shown in Fig. 2 and Fig.3 [3]. The distributionof residual stress after drawing shows tensile stress atthe surface and compressive stress at the center similar
to those found by neutron-based studies [3–6]. In addition, it was found that the internal residual stress generated by the drawing process tended to decrease by thesubsequent straightening processes in all three directions (in the bar’s hoop, radial, and axial directions). It is,therefore, clear that devising appropriate plastic forming processes can decrease the internal residual stressin a product.

4. Numerical study
The simulation was done using open source software (integrated structural analysis system DEXCSWinXistr). The rod and die setup were developed in
SALOME and imported to EasyISTR. FrontISTR was used
for the calculations and ParaView was used to analyze
the results. The drawing process was simulated using
the die geometry. The die was fixed and a 12 mm rod
with both ends tapered to a 10 mm diameter was pulled
out to enable it to be pulled out smoothly. The lot wasforced to displace and pass through the die.
The distributions of stresses during drawing isshown in Fig. 4. After exiting the die, tensile stress remained in the surface layer and compressive stress inthe center as in the neutron experiment. Although themechanism of residual stress generation is complex, it
can be shown as a figure by FEM.

Figure 4.	Distribution of residual stresses during drawing in
the axial direction by FEM.
Figure 2.	Distribution of residual stresses after drawing.

Figure 3.	Distribution of residual stresses after spinner androll straightening.

12

MLF Annual Report 2021

5. Summary
The residual stresses generated by the cold-drawing
process were reduced by subsequent straightening, andthe distribution of residual stresses by FEM simulation
was consistent with the measured values by neutron
diffraction. The combination of neutron diffraction andFEM can provide a detailed understanding of the residual stresses and mechanisms of the manufacturing
process of the drawing process.
Acknowledgements
We would like to extend our deep appreciation
to Kiyotaka Kashiwa and Takahiro Maeshima of theIndustrial Technology Innovation Center of Ibaraki
Prefecture for their kind cooperation during the residual
stress simulations. A part of this research was supported
by Hitachinaka Techno Center, Inc.

Research and Development Highlights

References[1] M. Asakawa, W. Sasaki, and S. Shishido: Wire J. Int 10(2002) 68–72.
[2] C.R. Liu and Y.B. Guo: Int. J. Mechan. Sci. 42 (2000)
1069–1086.
[3] S. Nishida, S. Nishino, M. Sekine, Y. Oka, S. Harjo, T.
Kawasaki, H. Suzuki, Y. Morii and Y. Ishii: Mater. Trans.
2021, 62, 667–674.
[4] J. M. Atienza, M. L. Martinez-Perez, J. Ruiz-Hervias, F.
Mompean, M. Garcia-Hernandez, and M. Elices: Scr.
Mater. 52 (2005) 305–309.
[5] T.F.de Souza, C.A.T. Soares, J. Zottis, R.M. Nunes, A.S.
Rocha, T. Hirsch: Mater Res. 16(2013) 508–14.
[6] J. Zottis, C.A.T. Soares Diehl, and A. da Silva Rocha: J
Mater Res. Technol. 7 (2018) 469–478.

S. Nishino1, S. Nishida2, M. Sekine2, Y. Oka1, S. Harjo3, T. Kawasaki3, H, Suzuki4, Y. Morii5, and Y. Ishii5
Graduate School of Science and Engineering, Ibaraki University; 2Akiyama Seiko Co., Ltd.; 3Neutron Science Section, Materials and Life
Science Division, J-PARC Center; 4Materials Science Research Center, Japan Atomic Energy Agency; 5Radiation Application Development
Association

1

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Research and Development Highlights

MLF Annual Report 2021

Hydrogen Storage by Earth-Abundant Metals
1. Introduction
Hydrogen can take on various chemical states inmaterials. Hydrides, which are compounds of hydrogen, exhibit diverse functionalities due to such various
chemical states of hydrogen [1]. Recently, hydrides withfunctionalities such as high-temperature superconductivity, H­− conduction, and fast ionic conduction havebeen extensively studied, while research on hydrogenstorage alloys, which have a history of more than halfa century of research and development, continues tobe pursued intensively to realize the hydrogen energybased society.
Hydrogen is expected to be a clean energy carrier that does not emit greenhouse gases when used.
Hydrogen can be converted from various primary energy sources and stored for a long time. Hydrogen has,
however, a problem of low energy density because
it is a gas at the ambient conditions at which we live.
Hydrogen storage alloys can store hydrogen in atomic
solid form, making it possible to increase the volumetrichydrogen density above than that of liquid hydrogen.
However, their gravimetric hydrogen densities are low.
In addition, when mass-produced and used as an energy
storage material, the cost of the material is also an issue.
In the search for hydrogen storage alloys, the guideline of “alloying metals with high- and low-hydrogen affinities” is well known [2]. Not only hydrogen storage
alloys, but also other hydrides that have been synthesized follow this guideline without exception. Here, thedefinition “metal with high-hydrogen affinities” refers tometals that easily form hydrides with hydrogen composition close to their stoichiometric one at near ambientpressure, and include elements from the alkali metals
to group V in the periodic table and Pd. In contrast, thedefinition “metals with low-hydrogen affinities” refers
to metals that require high hydrogen pressure above
1 GPa to form hydrides with a hydrogen composition
close to their stoichiometric one, and include elementsin the Cr to Cu groups of the periodic table, excluding
Pd. In the case of hydrogen storage alloys, hydrides consisting of metals with high-hydrogen affinities require
high temperatures for hydrogen release because they
are too stable. By mixing a metal with low-hydrogen affinity, thermodynamic stability of such hydrides is tuned
so that hydrogen can be released at an appropriate temperature. The basis of this idea is that when two metals
are alloyed and hydrogen is absorbed, the stability of
the alloy hydride is intermediate to the stability of the14

hydrides of the constituent elements. Based on this idea,
stable hydrides should not be obtained by combining
only metals with low-hydrogen affinities.
While this guideline for the search of hydrogen storage alloys is very useful, it also limits the scope of material exploration. Hydrogen storage alloys such as LaNi5
and TiFe with excellent hydrogen absorption and desorption properties have been developed and are alreadyin practical use. These alloys contain relatively expensive
metals and there is a need to improve the gravimetrichydrogen density. There are, however, not many effective metal combinations within the scope of the abovementioned search guidelines, and it seems to be difficult
to solve these problems by material search.
We thought that if it were possible to obtain hydrides composed solely of metals with low-hydrogenaffinities, without being restricted by the conventional
search guidelines for hydrogen storage alloys, the scopeof material exploration would be dramatically expanded. We are exploring the hydrogenation reactions ofaluminum-based alloys, where aluminum is one of themost lightweight and inexpensive metals among metals with low-hydrogen affinities. Recently, we have obtained results showing that aluminum iron alloys form
hydrides, contrary to conventional search guidelines [3].
Now we need more than 7 GPa to hydrogenate the aluminum iron alloy. However, the resulting hydrides canbe thermodynamically stable even near ambient pressure. In other words, the obtained material can storehydrogen around ambient pressure.
2. Experimental
The high-pressure hydrogenation experiments werecarried out using a cubic-type multi-anvil press [4]. The
starting material was Al13Fe4 alloy prepared using an
arc-melting furnace. The obtained button-shaped ingot
was crushed and compressed into a disk shape. The disk
was set in a sample capsule made of boron nitride. The
sample was placed in a hydrogen-sealed capsule madeof NaCl with an internal hydrogen source of AlH3 or AlD3,
set in a cubic pressure medium with a graphite heaterfor heating, and pressurized in a cubic-type multi-anvilpress. The sample was pressurized to 9 GPa at room
temperature and then heated to 750°C with a constantload applied to the anvil, which can be regarded as an
approximately isobaric condition. After reaching 750°C,
the sample was held in hydrogen for approximately
2 hours, then the temperature was lowered to room

MLF Annual Report 2021

temperature and the pressure was reduced to ambientcondition. The above process was observed in-situ by
powder X-ray diffraction measurement at the beamline
BL14B1 at SPring-8 [5]. Samples recovered at ambientconditions were characterized by powder X-ray diffraction, powder neutron diffraction at NOVA at the Materialand Life Science Experimental Facility (MLF) of the Japan
Proton Accelerator Research Complex (J-PARC), and differential thermal balance-mass spectrometry (TG-MS).
3. Results and discussion
Figure 1 shows the X-ray powder diffraction profile
of Al13Fe4 alloy under high hydrogen pressure and hightemperature. Hydrogen was released from the hydrogensource at about 600°C. At the same time, a decrease in
the intensity of the Bragg peaks from Al13Fe4 and the appearance of new Bragg peaks were observed. This profilechange was completed in approximately 5 minutes after
reaching 750°C. It is difficult to determine whether hydrides are formed from this in situ synchrotron radiation
profile alone, however, when combined with the resultsof the analysis of the recovered sample described below, it was found that hydrogen treatment at 750°C and9 GPa leads to hydrogenation of the Al13Fe4 alloy to forma new hydride, Al3FeH4. Here, the aluminum concentration of the starting material alloy is slightly (about 8 at%)higher than that of the hydride. It is possible to obtain
Al3FeH4 by preparing an alloy with an Al3Fe composition and hydrogenating it under the same temperatureand pressure conditions. However, this would require a
holding time of more than 12 h for the hydrogenation
reaction. The excess aluminum may work as self-flux andenhance the hydrogenation reaction rate.

Research and Development Highlights

The new hydride Al 3FeH4 could be recovered atambient conditions. To confirm that the recovered sample was hydride, hydrogen desorption from the recovered sample upon heating was measured using TG-MS.
Hydrogen desorption around 150°C was observed. Since
no release of gaseous species other than hydrogen was
detected, the hydrogen content of the sample was calculated from the weight loss during hydrogen release,and it was calculated to be approximately 2.9 wt%.
Although this study is still in the basic research stage
and comparisons with practical hydrogen storage alloys
may not be meaningful, it is noteworthy that Al13Fe4,
which are thought not to absorb hydrogen, have thehydrogen composition of 2.9 wt% that is comparable tothose of hydrogen storage alloys LaNi5 and TiFe.
In the high pressure and high temperature synthesis of novel hydrides, in-situ observation by synchrotron
radiation X-ray diffraction is a very powerful tool for exploring synthetic conditions and evaluating stability ofthe obtained hydrides. However, since it is in principledifficult to obtain information on hydrogen using X-rays,
it is necessary to take other measures. We performed
neutron diffraction measurements and structural refinement by Rietveld analysis on Al3FeD4 recovered atambient conditions.
A schematic of the crystal structure obtained by the
Rietveld analysis is shown in Fig. 2(a). As confirmed by
the profile change obtained by in situ synchrotron radiation observation (Fig. 1), the crystal structure is completely different from that of Al13Fe4. It was suggested
that a different type of hydride was formed from an interstitial hydride, in which hydrogen atoms were locatedat interstitial sites of original alloys while maintaining

Figure 1.	Series of in-situ synchrotron radiation X-ray diffraction profiles of Al13Fe4 during hydrogenation reaction at 9 GPa. Opensquares indicate Bragg peaks from Al3FeH4. The right graph indicates temperature change during the measurement.

15

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MLF Annual Report 2021

Figure 2.	(a) schematic of the crystal structure of Al3FeH4. (b) schematic of the structure unit around the iron atom. (c) schematic of
the crystal structure of Li4FeH6 and [FeH6]4– complex ion in the hydride.

their crystal structures. The space group of the obtained
crystal structure is P3c1 (No. 158) and it appears to bea simple structure with relatively high symmetry witha unit cell volume of V = 153.7 Å3. Closer inspection of
the crystal structure shows that both hydrogen sites andmetal sites contain many partially occupied sites. Let us
examine the crystal structure in more detail, focusing on
the metal-hydrogen bonding.
Figure 2(b) shows a schematic of hydrogen sitesaround an iron atom. There are six hydrogen sitesaround the iron atom, forming an octahedron centeredon the iron atom. This shape and the distance between
the iron and hydrogen sites are close to those of the[FeH6]4 – complex ion (Fig. 2(c)) in typical complex hydrides, Mg2FeH6 and Li4FeH6. However, the [FeH6]4– complex ion in the complex hydride is regular octahedraland the hydrogen sites are fully occupied, while thestructural unit in Al3FeH4 is partially occupied with 1/3hydrogen sites and the octahedron is distorted fromthe regular octahedron. We believe that the structuralunit observed in Al3FeH4 is similar to the precursors of[NiH4]4 – complex ion [6] reported in the hydrogenation
process of LaMg2Ni. The thermodynamic stability of thehydride is thought to be enhanced by the formation of
precursor-like units of a complex ion in Al3FeH4. These
results suggest that controlling the chemical state ofhydrogen can enable us to produce novel hydrides thathave not been obtained so far.

Acknowledgements
This work was supported by JSPS KAKENHI Grantin-Aid for Scientific Research on Innovative Areas“Hydrogenomics” (Nos. JP18H05513 and JP18H05518)
as well as JSPS KAKENHI (No. JP22H01821) and grants
from the Inter-University Cooperative Research Programof the Institute for Materials Research, Tohoku University(Proposal Nos. 20K0022, 202012-RDKGE-0066, and202112-RDKGE-0025). The crystal structures shown in
Fig. 2 were drawn using VESTA program [7].
References[1] S. Takagi and S. Orimo, Scr. Mater. 109, 1 (2015).
[2] A. Züttel, Mater. Today 6, 23 (2003).
[3] H. Saitoh, T. Sato, M. Tanikami, K. Ikeda, A. Machida,
T. Watanuki, T. Taguchi, S. Yamamoto, T. Yamaki, S.
Takagi, T. Otomo, and S. Orimo, Mater. Des. 208,
109953 (2021).
[4] Y. Fukai and N. Okuma, Jpn. J. Appl. Phys. 32, L1256(1993).
[5] H. Saitoh, A. Machida, K. Aoki, Chin. Sci. Bull. 59,
5290 (2014).
[6] T. Sato, K. Ikeda, M. Matsuo, K. Miwa, T. Otomo, S.
Deledda, B.C. Hauback, G. Li, S. Takagi, and S. Orimo,
Int. J. Hydrogen Energy 42, 22449 (2017).
[7] K. Momma and F. Izumi, J. Appl. Crystallogr. 41, 653(2008).

H. Saitoh
Quantum Beam Science Directorate, National Institutes for Quantum Science and Technology

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MLF Annual Report 2021

Liquid Structure in Superconcentrated Electrolytes
for Next Generation Aqueous Li ion Batteries
1. Introduction
Aqueous lithium ion batteries (ALIBs) have received
much attention as the next generation lithium ion batteries (LIB) because of their favorable safety featuresand environmental friendliness. Water is not used in
the current LIB due to its narrower electrochemical
window, however, Suo et al. have resolved this problem with a simple increase of the Li salt concentration,
which is called Water-in-Salt electrolyte consisting of
21 mol kg−1 lithium bis-(trifluoromethanesulfonyl)amide(LiTFSA), with molar ratio [H2O]/[LiTFSA] = 2.6 [1]. It is
assumed that the intermolecular interaction with the
Li+ causes the change of the HOMO energy level of thewater molecule, which makes the anodic potential limit
expand through a thermodynamic mechanism [1, 2].
Furthermore, the stability of the solid electrolyte interphase (SEI) is important to expand the life and increase
the energy of the battery because the passivation thinlayer restrains further electrolyte decomposition and allows reversible Li+ transport between electrodes. Suo et
al. revealed the differences between the structure of theSalt-in-Water and that of the Water-in-Salt solutions by
MD simulations and that these conditions inside solutions, such as liquid structure and Li+ local structure, influence the SEI formation [1]. Therefore, it is essential tounderstand the liquid structure of the electrolyte solution, especially, the local structure of Li+ in the solutions
at molecular level.
The structure of concentrated and super-concentrated LiTFSA aqueous solutions has been reported boththeoretically and experimentally [2, 3]. More knowledge of the liquid structure and the Li+ local structure
in super-concentrated aqueous LiTFSA solutions is stillneeded because the local structure is crucial for the
ARLIBs performance. Here, the Li+ local structure in the
super-concentrated LiTFSA aqueous solution is determined using neutron total scattering experiments with
6/7
Li and H/D isotopic substitution technique. We founda formation of oligomer and a significantly weak hydrogen-bonded interaction.
2. Experimental
We prepared the typical super-concentrated aqueous LiTFSA solutions (6Li samples, (6LiTFSA)0.25(D2O)0.75
a n d ( 6 L i T F S A) 0 . 2 5 ( 0 H 2 O ) 0 . 7 5 , a n d n a t L i s a m p l e s,
( nat LiTFSA) 0.25 (D 2 O) 0.75 , ( nat LiTFSA) 0.25 ( 0 H 2 O) 0.75 and(natLiTFSA)0.25(0-2H2O)0.75). The solutions were sealed into
Ni-V null alloy cells (8 mm in diameter and 0.1 mm inthickness). Neutron diffraction measurements were carried out at 25°C using the NOVA total scattering spectrometer installed at BL21 of the MLF high intensity
pulsed neutron source in J-PARC, Tokai, Japan. The incident beam power of the proton accelerator was 200 kW.
The observed total interference term of solutions, i(Q),consists of the sum of intra- and intermolecular interference terms.
intra (

( )=

inter

)+

(1)

( )

i intra(Q) includes intramolecular interference terms of
H2O and TFSA, and the respective i intra(Q) is evaluated byintra
molecular () = ∑∑ ≠)/()2) sin(

exp(

2

2

/

(2)

where, lij and rij stand for the root-mean-square amplitude and internuclear distance, respectively.
The Fourier transform of i(Q) leads to the real spacecorrelation function, the total distribution function g(r),( ) = 1 + (2 2

( )

(3)

) − 1 + [ LiLi ( ) − 1]

(4))−1 (∑)−2 ∫0 max

where, ρ is the number density of the stoichiometricunit. ci and bi are the number and the coherent scattering length of atom i involved in the stoichiometric unit.
The upper limit of the integral was set to 40 Å–1 in thepresent analysis.
If the two solutions have identical compositions,
except for the isotopic ratio of Li, the difference in theobserved scattering intensities of these solutions gives
the first-order difference function, ΔLi(Q). The ΔLi(Q) normalized for the stoichiometric unit can be represented
as a linear combination of partial structures, aLij(Q), involving correlations form the Li-j pair
∆Li ( ) = ∑

Li

=
and
( 6Li
nat ) . The real-space first order differenceLifunction, GLi(r), distribution function around Li+, is obtained by Fourier transform of ΔLi(Q).
The partial distribution function, gLiH(r), is obtainedby the Fourier transform of the Li-H partial structure
factor, aLiH(Q). Structural parameters concerning theinteractions between Li + and H 2O or TFSA – were determined through the simultaneous least-squares

where
2

2

Li
2

=2

Li (

(

6

Li

nat

Li )

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Research and Development Highlights

MLF Annual Report 2021

fitting of the first-order difference function observedfor 0 H 2 O solution, 0H Δ Li (Q), and 2 Li H 6Li −nat
employing the following
D [ LiH ( ) − 1]Limodel function
0H model(∆Li) = ∑ 2 Li Li

(

6

Li

nat

Li ) exp (2) × sin( Li )/( Li ) + 4 (∑ Li + ) ×
exp ( 02 2 /2)[ 0 cos( 0 ) − sin( 0 )] −3
model
(
LiH

2
) − 1 = ∑ LiH exp ( LiH′2 2( LiH ) + 4 exp (
/2)[
0
−3
sin( 0 )]

2
Li

2

/

(5)

2

/2) sin( LiH )/0 cos(0) −(6)

where nLij denotes the coordination number of j atomaround Li+, respectively. Parameters lLij and rLij are theroot-mean-square amplitude and internuclear distanceof the Li+…j pair, respectively. The long-range parameters r0 and r0’ are distances beyond which continuous
distribution of atoms around Li+. To determine the structural parameters, nLij, lLij, rLij, l0, l0’, r0 and r0’, simultaneous
least squares fitting procedures to the observed 0HΔLi(Q)and aLiH(Q) were performed in the range of 0.1 ≤ Q ≤20 Å–1.
The intermolecular H-H, X-H and X-X (X: Li, O, S, C,
F, N) partial structure factors, aHHinter(Q), aXHinter(Q) andaXXinter(Q) were derived from the linear combination ofintermolecular interference terms observed for natLi
samples, (natLiTFSA)x(D2O)1-x, (natLiTFSA)x(0H2O)1-x, and(natLiTFSA)x(0-2H2O)1-x.

Figure 1.	Intermolecular H-H, X-H, and X-X partial distributionfunctions, gHHinter(r), gXHinter(r) and gXXinter(r), observed
for aqueous 25 mol% LiTFSA solutions. Reprinted
with permission from [6]. Copyright 2021 American
Chemical Society.

18

3. Results and discussion
Neutron diffraction with the isotopic substitution
method is one of the most powerful techniques to obtain direct insight into hydrogen bonding and the environmental structure around Li+. Figure 1 represents theinter-molecular H-H, X-H and X-X partial distributionfunctions observed for aqueous 25 mol% LiTFSA-*H2O
solutions (X excludes H atom). These partial distributionfunctions were obtained by the Fourier transformationintermolecular H-H, X-H, and X-X (X : Li, C, N, O, F, S) partial structure factors, respectively. The position of thefirst inter-molecular peak appearing at r ~ 2.8 Å of thepresent gHHinter(r) is much longer than that observed for
liquid pure water (~2.44 Å) implying that the interaction between the nearest neighbor water molecules inthe solution should be significantly weaker. The intermolecular hydrogen-bonded interaction between theneighboring water molecules is well known to be characterized by the inter-molecular O…H peak located at
r = 1.81~1.84 Å, in the inter-molecular gOH(r) function.
In the present inter-molecular gXHinter(r), no indication
can be observed for the nearest neighbor hydrogenbonded interaction. This suggests significantly weakerhydrogen-bonded interaction in the aqueous 25 mol%
LiTFSA solution.
Figure 2 shows the Li +…H partial distributionfunction gLiH(r) and the distribution function aroundLi +, 0HG Li(r). 0HG Li(r) and g LiH(r) were obtained by the

Figure 2.	The Li-H partial distribution function, gLiH(r), anddistribution function around Li+, 0HGLi(r), observed
for the aqueous 25 mol% LiTFSA solutions (dots).
Fourier transform of the calculated aLiH(Q) -1, and
0H
ΔLi(Q) are indicated by solid lines. The short- andlong-range interactions are denoted by broken- anddotted lines, respectively. Reprinted with permission
from [6]. Copyright 2021 American Chemical Society.

MLF Annual Report 2021

Fourier transformation of 0HΔLi(Q) and aLiH(Q)-1, respectively. The calculated model structure agrees well withthe experimental 0HGLi(r) and gLiH(r). The present value ofrLiO (H2O) for the first hydration shell of Li+, rLiO = 1.970 ±0.003 Å, agrees well with values reported for the otheraqueous solutions (1.96 ± 0.02 Å for 14.0 m LiCl [4]).
The present rLiO value for the nearest neighbor Li+…
TFSA− interaction, 1.966 ± 0.005 Å, agrees with thatobserved in organic solution (rLiO = 1.98 ± 0.01 Å for
25 mol% LiTFSA-EC solution [5]). The coordination numbers of the oxygen atoms of H2O and TFSA− molecules in
the first hydration shell of Li+ are determined to be 1.930± 0.006 and 2.28 ± 0.01, respectively.
To obtain a detailed picture of the Li ion local structure, we demonstrated MD simulations. The simulated
neutron total interference terms are in good agreementwith the experimental data. The coordination numbersof Li-O in the H2O and TFSA are between 2.3 and 3.7 andbetween 1.7 and 2.8, respectively. The experimental coordination number of H2O is significantly smaller thanthat predicted from the MD simulations. On the other
hand, the experimental coordination number of TFSA ismuch larger than the estimated from the MD simulation.
This suggests that a variety of TFSA− and H2O coordination manners would exist in the solution, in particular, an oligomer is formed in which the monodentate
TFSA cross-links Li+, as shown in the liquid structure of
the 25 mol% LiTFSA-H2O solution obtained by the MD
simulation.

Research and Development Highlights

4. Future plans
Here, we demonstrated the neutron scattering withthe 6/7Li and H/D isotopic substitution technique, whichevidently reveals the Li+ local structure in the super concentrated LiTFSA aqueous solution for the ALIB. More recently, several super concentrated electrolyte solutions
have been proposed to build electrochemical devices
such as Li ion batteries with high energy density andhigh safety. The liquid structure plays a crucial role inrealizing the next generation batteries. Neutron scattering techniques strongly support further development ofscience and technology in this field.
References[1] L. Suo et al., Science, 350 938 (2015).
[2] Y. Yamada et al., Nat. energy, 1 16129 (2016).
[3] T. Tsurumura et al., Anal. Sci., 35 289 (2019).
[4] I. Howell and G. W. Neilson, J. Phys.: Condens. Matter,
8 4455 (1996).
[5] S. Maeda et al., J. Phys. Chem. B, 121 10979 (2017).
[6] H. Watanabe et al., J. Phys. Chem. B, 125, 7477
(2021).

Figure 3.	Liquid structure of the aqueous 25 mol% LiTFSA
solution estimated by MD simulation. Reprinted
with permission from [6]. Copyright 2021 American
Chemical Society.

H. Watanabe1, Y. Umebayashi2, and Y. Kameda3
1Depertment of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science; 2Graduate School of Science andTechnology, Niigata University; 3Department of Material and Biological Chemistry, Faculty of Science, Yamagata University

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MLF Annual Report 2021

Distinguishing Adsorbed and Deposited Ionomers in theCatalyst Layer of Polymer Electrolyte Fuel Cells Using
Contrast-Variation Small-Angle Neutron Scattering
1. Introduction
Polymer electrolyte fuel cells (PEFCs) are indispensable devices for hydrogen economy. Meanwhile, innovation in component materials and manufacturing
processes as well as improvement in their development
efficiency are required to achieve higher-power andlower-cost PEFCs. Thus, we are creating a digital twinof a PEFC system to design and optimize the enormousparameters in silico.
In the PEFC system simulation, power generation ina catalyst layer of PEFC has been tackled while complicated by structure modeling difficulties due to lack ofexperimental data, especially in operando conditions.
Since neutrons are a promising probe, we report anapplication of small-angle neutron scattering (SANS)
measurements on a catalyst layer to investigate the effect of their multi-component hierarchical structure on
the PEFC performance.
2. Ionomer distribution in the catalyst layer of PEFC
The power of a PEFC increases as the electrochemical reaction between oxygen and protons in the catalyst
layer becomes smoother. A schematic diagram of thecatalyst layer is shown in Fig. 1. The reaction takes placeon the catalyst nanoparticles, such as platinum, which

Figure 1.	Typical components of a catalyst layer for polymer electrolyte fuel cells. Catalyst nanoparticles
are supported on carbon particles which form a
porous network structure with voids. The surfaceof the network is coated with ionomer thin films.
Proton conductivity in the ionomer should be highenough for a smooth reaction with oxygen.

20

are supported on carbon particles forming a porous
network structure. Oxygen diffuses through the voids tothe catalyst and electrons are provided via the carbon.
Protons conduct through a fluorinated polyelectrolyte
thin film called ionomer, which continuously covers thesurface of the catalyst-supported carbon (Pt/C).
In the catalyst layer, ionomers do not coat homogeneously the Pt/C. In Fig. 2, a scanning electron microscope image of a catalyst layer is shown. The grayparticles are the ionomer-coated Pt/C aggregating hierarchically with sizes of tens to hundreds nanometers.
The white spots on the aggregates are the platinum
catalysts. Although the coating ionomer is not clearly
distinguished from the Pt/C, the ionomer appears tobe deposited between the Pt/C particles on which theionomer is adsorbed. These two types of ionomers are
expected from the formation process of the catalyst layer by applying and drying of a catalyst ink (dispersionof Pt/C and ionomer in a solvent) as well. Therefore, we
focus on the thickness of the adsorbed ionomer and thevolume fraction of the deposited ionomer as descriptors
representing the heterogeneity of the ionomer distribution, which can be used to explain proton conduction
and oxygen diffusion in a catalyst layer.

Figure 2.	Image of a catalyst layer observed by scanningelectron microscopy. Distribution of an ionomer
coating on carbon particles looks heterogeneous;adsorbed parts and deposited parts could be observed for the ionomer.

MLF Annual Report 2021

3.	Contrast-variation small-angle neutron scatteringfrom the catalyst layer
We applied contrast-variation small-angle neutron
scattering (SANS) to quantitatively evaluate the ionomer
distribution in the catalyst layer [1]. Since the catalyst
layer is regarded as a three-component system consisting of Pt/C, ionomer, and voids, the scattering curves
reflect the self-correlation for the Pt/C and the ionomer,
respectively, as well as the cross-correlation between
the Pt/C and the ionomer. Although the scattering froma three-component system is hard to model-fit in general, the three correlation functions can be analyzed separately by varying the contrast of one component with an
isotope. The SANS curves of a catalyst layer measured
with six contrasts of the void-filling liquids are demonstrated in Fig. 3 by decreasing the H/D ratio from the top
to bottom. Here, after calculating three kinds of correlation curves, a core-shell structure with the Pt/C core andthe ionomer shell under consideration of the density
fluctuation in the ionomer were applied with referringto the catalyst ink used to fabricate the catalyst layer [2].
The fitting parameter for the shell thickness was 5.1
nm, indicating that the adsorbed ionomer coats on the
Pt/C uniformly. In contrast, density fluctuation with 7.8
nm was observed for the ionomer, due to the depositedpart because the thin adsorbed part could not affect it.
From the peak intensity of the fluctuation, the volume
fraction of the deposited ionomer was evaluated to be
8.5 vol% of the total catalyst layer volume, which was

Research and Development Highlights

consistent with the volume fraction of adsorbed ionomer calculated from the specific surface area of the
Pt/C. Furthermore, the scattering curve for the crosscorrelation function between the Pt/C and the ionomer
was fitted by a model with adsorbed part only and nodeposited part, supporting the hypothesis that the deposited part has no positional correlation to the Pt/C
and arranges randomly.
4. Structure model of the catalyst layer
The structure of the catalyst layer has been quantitatively evaluated by contrast-variation SANS as represented in Fig. 4. The Pt/C structure is modeled as fractal
aggregates of spheres with a size distribution, where
two types of ionomers are distinguished: uniformly adsorbed thin one and randomly deposited thick one.
The two distinct types of coating ionomers are
considered to have a critical effect on the proton conduction in a catalyst layer, because the proton conductivity depends on the thickness of the ionomer, which
is about one order of magnitude lower at a thicknessof 10 nm than in the bulk as reported in [3]. Comparing
the proton conduction path to a road, the adsorbed partis a country road and the deposited part is a highway.
Therefore, it is proposed that the contribution of adsorbed ionomer is relatively small and the amount ofdeposited ionomer is dominant for the proton conduction in the catalyst layer.

H+

Figure 3.	Contrast-variation small-angle neutron scatteringof a catalyst layer, in which the voids are filled byliquids with a varying H/D fraction. Decrease of thescattering intensity is induced by a contrast change
in the voids.

Country road

Highway

Adsorbedionomer

Depositedionomer

Catalyst-supporting carbon particles
Figure 4.	Proton conduction mechanism in the ionomer ofa catalyst layer. The adsorbed part with a thin pathhas higher resistance than the deposited part.

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5. Conclusion
The distribution of the ionomer in the catalyst layer
was modeled by using contrast-variation small-angle
neutron scattering and the coating structure was distinguished between uniformly adsorbed and randomly
deposited ionomer on the catalyst-supported carbon.
The impact of the ionomer structure on the proton conduction in the catalyst layer was discussed by focusing
on the thickness dependence of the conductivity in theionomer. The amount of the deposited ionomer was responsible for the proton conductivity in a catalyst layer.
Acknowledgement
This research is a part of a collaboration between

J-PARC and Toyota Central R&D Labs, Inc. We thankJapan Atomic Energy Agency (JAEA), Comprehensive
Research Organization for Science and Society (CROSS),and High Energy Accelerator Research Organization forsupporting the project. The small-angle neutron scattering experiments were performed under the approval of
MLF Long-term Proposals (2019L0400).
References[1] M. Harada et al., ACS Omega, 6 15257 (2021).
[2] M. Shibayama et al., J. Appl. Polym. Sci., 131 39842(2014).
[3] G. Gao et al., Solid State Ionics, 357 115456 (2020).

M. Harada1, S. Takata2, H. Iwase3, S. Kajiya1, H. Kadoura1, and T. Kanaya2,4
Toyota Central R&D Labs., Inc.; 2Neutron Science Section, Materials and Life Science Division, J-PARC Center; 3Neutron Science andTechnology Center, CROSS; 4Institute of Materials Structure Science, KEK

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Research and Development Highlights

Evaluation of Interfacial Water between Polypropylene
and Si Substrate
1. Introduction
In transportation equipment, including automobiles,
an improvement in fuel efficiency via weight reduction
is urgently required to abate environmental pollution.
Accordingly, various parts, including structural materials
made from metals, have been replaced with polymer/
inorganic filler nanocomposites or metal/resin bonding materials. Isotactic polypropylene (PP) is a promising
polymer-matrix material for such materials. PP is not only
inexpensive but has superior mechanical properties andhigh stability in various chemical environments. However,
nonpolar PP does not strongly interact with the metal surfaces, resulting in weak bonding at the interface, which
degrades the mechanical properties and thermal conductivity of PP-based nanocomposites and metal/resin bonding materials. This weak bonding at the interfaces alongwith the hydrophilicity of the metal surfaces also lead tointerfacial water accumulation for substrates under hightemperature and high-humidity conditions, which are thetypical usage conditions of PP-based materials. Water accumulation further degrades the aforementioned propertiesof these materials as a result of weakening the interfacialinteraction [1, 2]. Therefore, it is necessary to quantitatively
evaluate the interfacial water accumulation between PP
and metal surfaces under humid conditions. We attempted to quantitatively evaluate the amount of interfacial
water by the neutron reflectivity (NR) measurement.
Neutron reflectometry is a powerful tool because whenused in combination with deuterated water (D2O) with anextremely high scattering length density (SLD) comparedwith those of polymers and metals, it enables a quantitative evaluation of the amount of water at interfaces [3, 4].
2. Experiment
PP powder with a molecular weight of approximately 250000 g/mol produced by Sigma Aldrich Co.
was used to prepare polymer thin films for this study. PP
thin films were prepared on Si wafers with diameters of
50 mm and thicknesses of 2 mm using the spin-coating
technique. First, PP powder was dissolved in p-xylene at
130°C. Polymer solution with concentrations of 1.2 wt%
was spun cast at 5000 rpm on a clean silicon wafer heated at 200°C.
NR measurements were performed at BL16 SOFIA,
which is a horizontal type time-of-flight neutron reflectometer installed in J-PARC MLF (Japan Proton

Accelerator Research Complex, Material and Life
Science Experimental Facility). Neutron pulses of 25 Hz
were generated with a wavelength band of 0.2 nm < λ< 0.88 nm. Reflectivity profiles were recorded at reflection angles of 0.3, 0.7, 1.6, and 3.5° to yield a q rangeof 0.07–3.5 nm–1. Here, q is the magnitude of the scat, where λ andtering vector defined by = 4 /θ are the wavelength of the incident neutrons and theincident angle, respectively.
The NR measurements of the PP films were performed in vacuum and at the saturated vapor pressureof D2O at 25°C using a simple sealed sample chamberwith a cup of D2O.
3. Results and discussion
Figure 1 shows the NR profiles obtained in vacuum
and at the saturated vapor pressure of D2O at 25°C for
the PP thin film. The NR data in vacuum could be represented well by a simple single-layer model consisting of a PP thin film on a Si wafer with a native oxide
layer. The best fitting result is denoted by the solid line
shown in Fig. 1. Meanwhile, the NR data obtained at thesaturated vapor pressure of D2O could not be entirely
reproduced by the single-layer model. In the NR profile
obtained at the saturated vapor pressure of D2O, a fringewith a relatively long period centered at approximately
1 nm–1 is superimposed on the short periodic fringe
structure originating from the PP layer, indicating that athin single layer is located at the interface of the sample;

Figure 1.	NR profiles of the PP thin film deposited on a Si
substrate in vacuum and at the saturated vapor
pressure of D2O. Single-layer model and two-layer
model were used to fit the NR data in vacuum andat the saturated vapor pressure of D2O, respectively.

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MLF Annual Report 2021

hence, the NR profile was represented by a two-layer
model with an additional interfacial layer. The fitting
result of the two-layer model is denoted by a solid line
in Fig. 1, indicating that the two-layer model can accurately represent the experimental data. The SLD profiles
in the vicinity of the interfacial region as the best fitting
results for the NR profiles obtained in vacuum and at thesaturated vapor pressure of D2O are shown in Fig. 2. Theinterfacial layer with a high SLD should be attributed tothe interfacial water accumulation because the interfacial layer has a much higher SLD than the surface oxide
layer located on the Si substrate.
We attempted to quantitatively evaluate the concentration profile of D2O at the interface between the
PP thin film and the Si substrate with a native oxide
layer [3]. Considering the SLD profile in the film thickness direction as the fitting result of the NR profile of
the Si wafer used in this study, the concentration profilesof Si, SiO2, and air in the film thickness direction have′( ), ′ 2 ( ) , and ′ ( ),been determined to berespectively, for the Si/SiO2/air system. When the PP
layer was spun-cast on the Si substrate, the concentra′ ( )in the Si/SiO2/
tion profile of the PP overlayer,′( )PP system could be assumed to be identical toin the Si/SiO2/air system. The concentration profiles of
Si, SiO2, D2O, and PP in the PP thin film deposited on
the Si substrate at the saturated vapor pressure of D2O
are denoted by ′′ ( ), ′′ 2 ( ), ′′ 2 ( ) , and ′′ ( ),′′respectively. 2 ( ) is determined as follows:′′ ( )
2

′′

′′

2

( )=

( )=
′′

′

′

2

( ) ∙ �1( ) ∙ �1

′′

′′

2

2

( )� …(3)

( )�

…(4)

( ) is the SLD profile as a function ofThe
the distance from the substrate surface (Fig. 2) and is
obtained as the best fitting result for the NR profileat the saturated vapor pressure of D2O (Fig. 1). The
,
,
, and
are the SLDs of Si,22
SiO2, D2O, and PP, respectively, and are 2.07 × 10−4,

( )
( )

…(1)

−2
3.30 × 10−4 , 6.35 × 10−4 , and −0.33 × 10−4,
respectively. The concentration (volume faction) profiles obtained using Eqs. (1), (2), (3), and (4) are shownin Fig. 3 [3]. The peak concentration of interfacial water
was approximately 0.5, and the full width of the peak inthe concentration profile of the water-rich layer was approximately 3 nm. These values are comparable to thoseobtained in previous studies [4, 5]. The driving forces ofwater accumulation at the interface are considered tobe electrostatic and dispersion forces working within arelatively short distance from the hydroxylated metaloxide surface [2]. Therefore, in almost all cases, the water-rich layer thicknesses were within 3 nm. The resultsin Fig. 3 seem reasonable.
In general, surface modifications of metal oxides
with silane coupling agents are performed routinely toenhance the interactions between nonpolar polymers
and metal surfaces and reduce water accumulation at
the interfaces owing to hydrophobization of the substrate surfaces. Therefore, we attempted to suppress

Figure 2.	SLD profiles of the PP thin film deposited on a Si
substrate in vacuum and at the saturated vapor
pressure of D2O, as the fitting results of NR data in
Fig. 1.

Figure 3.	Concentration profiles of Si, SiO2, D2O, and PP in
the PP thin film deposited on a Si substrate at thesaturated vapor pressure of D2O as a function of the
distance from the substrate surface.

=

24), ′′ 2 ( ) and ′′ ( ) are obtained by thefollowing equations with the substitution of values obtained from Eq. (1)′′ ( ) = ′ ( ) ∙ �1′′ ( )�
…(2)
2
′′ (

′′ (

2

)−
−

′ (

′ (

)−
)−

2

2

′

′

( )−
(
)−
2
2

′

′

MLF Annual Report 2021

water accumulation at the interface between a PP thinfilm and Si substrate by surface modification of thesubstrate by a silane coupling agent. A silane coupling
agent significantly prevents water molecules from accumulating at the PP/Si interface [6].
4. Conclusion
We quantitatively evaluated the water accumulation at the interface between the PP thin film and the Si
substrate using the NR technique. Based on the NR profile of the Si substrate with a native oxide layer and thatof the PP thin film deposited on it at the saturated vapor
pressure of D2O, the concentration profiles of Si, SiO2,
D2O, and PP can be obtained as a function of the distance from the substrate. The results clearly indicate that

Research and Development Highlights

a water-rich layer with a layer width of approximately 3
nm and a maximum concentration of 0.5 is formed at
the interface between the PP thin film and the Si substrate at the saturated vapor pressure of D2O.
References[1] K. T. Tan et al., Langmuir, 24 9189 (2008).
[2] K. Yoshizawa et al., Langmuir, 34 14428 (2018).
[3] K. Shimokita, K. Yamamoto, N. Miyata, Y. Nakanishi,
H. Ogawa, M. Takenaka, N. L. Yamada, and T.
Miyazaki, Langmuir, 37 14550 (2021).
[4] B. D. Vogt et al., Langmuir, 21 2460 (2005).
[5] E. P. O’Brien et al., Adv. Eng. Mater., 8 114 (2006).
[6] K. Shimokita, T. Miyazaki et al., Langmuir, 38 12457(2022).

T. Miyazaki1,2, K. Shimokita3,4, K. Yamamoto4, N. Miyata2, Y. Nakanishi5, H. Ogawa5, M. Takenaka5, and N. L. Yamada6
Office of Society-Academia Collaboration for Innovation, Kyoto University; 2Neutron Science and Technology Center, CROSS; 3Functional
Base Products Sector, Nitto Denko Corporation; 4Gradual School of Engineering, Nagoya Institute of Technology; 5Institute for Chemical
Research, Kyoto University; 6Neutron Science Section, Materials and Life Science Division, J-PARC Center, Institute of Materials Structure
Science, KEK

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MLF Annual Report 2021

Conformational Dynamics of a Multi-Domain Protein by
Neutron Scattering and Computational Analysis
1. Introduction
Proteins are composed of nanometer-sized 3D
structures called domains. Relatively large proteins arecomposed of multiple domains and are referred to as
multidomain proteins. While each domain has a stablestructure, the domains change their relative positions
and orientations through flexible hinge regions thatconnect the domains. In the case of the MurD protein,structure changes of the adenosine triphosphate (ATP)binding site are coupled with the domains (Fig. 1) [1].
Elucidation of such domain-scale structural dynamics
over the scales corresponding to the domain size is necessary to understand the mechanisms of protein functional expressions [1, 2].
In current structural biology, various experimental
techniques have been developed to analyze structuralchanges and dynamics of proteins. Each method only
partially reveals their realistic structure and dynamics.
Correlative structural analysis uses a combination of several techniques and is applied to clarify a more realistic
protein structure and its dynamics, which is also called
integrated structural biology. Quasi-elastic neutron scattering (QENS), such as neutron backscattering (NBS) andneutron spin echo (NSE), is one of the powerful methods
to unveil the equilibrium thermal fluctuations of a protein structure and a global diffusion in the nanometer
length and picosecond to nanosecond timescales [3,4].
We studied the dynamics of MurD, a typical multidomain protein, which is an enzyme involved in cell wall
synthesis and the conformational change upon ATPbinding is essential for its function. We combined QENS
and molecular dynamics (MD) simulation to elucidate
the correlation between the domain structure and thestructure of the ATP binding site.
2. Experimental procedures
MurD protein was expressed in E. coli strain BL21
(DE3), and purified. The protein solutions were preparedin D2O buffer with 20 mM Tris-HCl (pD 7.2), 200 mM
NaCl, 10 mM Dithio Threitol, and 0.05% NaN3 at a protein concentration of 57 mg/mL, where M indicate molarity (mol/L). An ATP analog adenylyl imidodiphosphate(AMP-PNP) and Mg2+ were added to the above protein
solutions for the ATP-bound state with 3 mM AMP-PNP
and 6 mM MgCl2.
NSE experiments were conducted using the NGANSE spectrometer at NIST in USA [5]. The data were collected over a scattering vector, Q, range from 0.03 Å–1 to0.21 Å–1 at 25 ˚C. The data were corrected for the scattering from the D2O buffer solvent and instrumental resolution effects to obtain I(Q, t)/ I (Q, 0), at several Q-values.
NBS experiments were conducted using BL02 at
J-PARC MLF in Japan [6]. The energy resolution was
12 μeV with an Si (111) crystal analyzer. The data werecollected over a Q range from 0.21 Å–1 to 1.79 Å–1 at
25˚C. The spectra of D2O buffer were subtracted fromthe protein solution spectra by taking the protein volume fraction into account. NBS spectra were fitted witha two-component model function, which describes internal motion and global diffusion.

Figure 1. (A) Close-up view of the ATP-binding site, in which the amino acid residues (R302, K115
and D317) are indicated as a ball-and-stick model. (B) Domain twisting motion.

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MLF Annual Report 2021

Dynamic light scattering (DLS) measurements were
performed using an ALV-5000 digital correlator (ALV,
Germany) at a laser wavelength of 632.8 nm. The resulting time-correlation function of the scattered intensity
g2(Q, t), which was directly derived from the measurement, was converted to the field time-correlation function g1(Q, t) using the Siegert relation. The intensity waswell fitted with a single exponential, and the translational diffusion coefficient D0 was obtained. To eliminate theeffects of aggregates, CONTIN analysis was used.
3. Results and discussion
Figure 2A shows the effective diffusion coefficient,Deff, obtained by the NSE experiments. The coefficient
includes contributions from translational and rotational
diffusion as well as internal domain motions [3]. The low
Q limit of Deff reasonably corresponds to D0 obtained by
the DLS [7]. The self-diffusion coefficients were obtained
by NBS, and the rotational diffusion coefficients were
calculated using HYDROPRO [3]. The apparent diffusion
coefficients derived from domain motion, ΔDeff, were
calculated by subtracting the self-diffusion and rotational diffusion contributions from Deff. Shown in Fig. 2B are
ΔDeff in the Apo and ATP bound states. The peak aroundQ = 0.15 Å-1 is reduced by ATP binding. The origin of the
reduction of ΔDeff was identified as a suppression of atwisting domain motion (see Fig. 1B) by the principal

Research and Development Highlights

component analysis of the trajectories of our molecular
dynamics simulations [8, 9]. Furthermore, the computational analysis showed that this domain motion is linked
to the fluctuation of the side chain of the ATP-bindingsite (Fig. 3), indicating that the fluctuation of the local
structure controlled by the domain motion is importantfor ATP binding. The present study identified the detailsof the changes in domain motions upon ATP binding forthe first time and advanced our understanding of themolecular mechanism of MurD enzyme activity.
This analysis reveals that the amino acid residues of
the active site are not randomly fluctuating thermally,
but are controlled by the cooperative thermal fluctuations of the domain structure. As such, understandingof the relationship of structural dynamics in different
hierarchies is important for elucidating protein function.
4. Outlook
In this work, we studied the domain motions andconformational variations of the MurD enzyme bothcomputationally and experimentally. We found thatthe binding of ATP suppresses the nanosecond domain
dynamics. The ligand bindings change the interdomain
dynamics as well as the local structures at the active
site, and more interestingly, the structural dynamics inthe different spatial scales are coupled with each other.
The large-scale Brownian motions of interdomain con-Figure 2. (A) Effective diffusion coefficients of MurD in the apo state. The solid lines indicate the calculated diffusion coefficients using HYDROPRO, including the translational and rotational diffusions. The square and triangle indicate the diffusion coefficients by DLS and NBS experiments,
respectively. (B) The difference in the experimental effective diffusion coefficients and the calculated rotational diffusion coefficient, ΔDeff.

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Research and Development Highlights

MLF Annual Report 2021

Figure 3. Time course of PCA axis of twisting mode and distance between Cα carbons ofK115 and R302 in the apo state.

formation on the nanosecond timescale regulate the
enzymatic reaction through the dynamical coupling. To
uncover complex mechanisms of enzymatic reactions,computational analyses and integration of different experimental techniques that cover different space andtimescales are effective.
The identification of any commercial product ortrade name does not imply endorsement or recommendation by the National Institute of Standards andTechnology.

References[1] T. Saio et al., Sci. Rep., 5 16685 (2015).
[2] H. Nakagawa et al., Biophys. J., 120 3341 (2021).
[3] R. Inoue et al., Biophys. J., 99 2309 (2010).
[4] F. Roosen-Runge et al., Proc. Natl. Acad. Sci. USA. 108
11815 (2011).
[5] N. Rosov et al., ACS Symp. Ser. 739 103 (1999).
[6] K. Shibata et al., JPS Conf. Proc. 8 036022 (2015).
[7] W. Doster et al., Biophys. J., 93 1360 (2007).
[8] A. Kitao et al., Curr. Opin. Struct. Biol., 9 164 (1999).
[9] N. Smolin et al., Biophys. J., 102 1108 (2012).

H. Nakagawa1,2, T. Saio3, M. Nagao4,5,6, R. Inoue7, M. Sugiyama7, T. Tominaga8, and Y. Kawakita2
Materials Sciences Research Center, JAEA; 2Neutron Science Section, Materials and Life Science Division, J-PARC Center; 3Divisionof Molecular Life Science, Institute of Advanced Medical Sciences, Tokushima University; 4NIST Centre for Neutron Research, National
Institute of Standards and Technology; 5Department of Materials Science and Engineering, University of Maryland; 6Department of Physics
and Astronomy, University of Delaware; 7Institute for Integrative Radiation and Nuclear Science, Kyoto University; 8Neutron Science andTechnology Center, CROSS

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Research and Development Highlights

Spin Texture Induced by Non-Magnetic Impurity in the
Triangular Lattice Antiferromagnet h-Y(Mn,Al)O3
1. Introduction
Impurities are an unavoidable problem in condensed matter physics and material science studies.
As magnetic materials are no exception to this, understanding how impurities affect magnetic properties
is one of the important research topics. This issue becomes more crucial in frustrated magnets; impurities infrustrated magnets are expected to cause very unusual
phenomena compared to magnets without frustration.
A representative example is continuum-like dynamicalsusceptibility induced by impurities, similar to that ofquantum spin liquid (QSL) and thus usually concealing
the true nature of several QSL candidates [1, 2].
When it comes to frustrated magnets with longrange order, it was proposed that impurities can significantly modify the original spin configuration [3, 4].
This is because an impurity can relieve the frustration,
leading to a change in the local spin arrangement(Fig. 1). Interestingly, this change can be transmitted
to a very long distance from the impurity, forming a giant spin texture like a Skyrmion [5]. However, the presence of such a texture has yet to be confirmed by any
experiment.
In this report, we present the experimental results
combined with theoretical analysis supporting the presence of the spin texture. We have studied this problem
experimentally by replacing some Mn ions with nonmagnetic aluminum (Al) in h-YMnO3, a geometricallyfrustrated triangular lattice antiferromagnet having 120°magnetic order. We successfully grew large single-crystal h-YMn1-xAlxO3 with x = 0, 0.1, and 0.15. Using inelastic
neutron scattering, we measured the spin dynamics ofas-grown h-YMn1-xAlxO3 and found clear traces of thespin texture [6].
2. Spin-wave spectra of YMn1-xAlxO3 (x = 0, 0.1, 0.15)
The spin-wave spectra of h-YMn 0.9 Al 0.1 O 3 andh-YMn0.85Al0.15O3 were measured using the 4SEASONS
time-of-flight spectrometer (BL1). Figure 1 shows themeasured spectra along the high-symmetry momentum
contour, including a comparison with those of pristineh-YMnO3. The linewidth broadening appears due to Al
doping over a wide momentum space, typical behavior of magnetic materials with impurities. However, wefound that the amount of linewidth broadening was
highly momentum-dependent. As demonstrated by astack of const-Q cuts along the C-B line (Fig. 2), magnon
linewidth broadening was much larger in the Brillouinzone boundary than in the zone center. This is unusual
since magnon decay due to a typical impurity effectshould be momentum-independent; impurities act as apoint-like scattering potential to magnons, whose scattering cross-section should be uniform regardless of thescattered direction [5]. Only a spatially-extended object
can induce such momentum-dependent damping [5],which would be related to the spin texture in our case.

Figure 1.	(Left) Non-collinear 120° magnetic order of h-YMnO3 (grey arrows) and the formation of spin texture (blue arrows) by anon-magnetic impurity. (Right) a–c, Spin dynamics of h-YMn1-xAlxO3 measured by inelastic neutron scattering. d–f, Calculated spin-wave spectra of h-YMn1-xAlxO3 with spin texture originating from Al impurities.

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MLF Annual Report 2021

3. Theoretical calculations
To further confirm the presence of the spin texture,
we calculated the theoretical spin-wave spectra with
non-magnetic impurities. First, the correct magnetic
ground state of h-YMn1-xAlxO3 was derived by the conjugate gradient method with simulated annealing on a
30 × 30 triangular lattice. We used the spin Hamiltonian
obtained from the spin-wave spectra of h-YMnO3 [7]. As
expected, the calculations yield spin configurations containing the spin texture mentioned earlier. Next, we calculated the dynamical structure factor with these spin
configurations; the results are shown in Fig. 1d–f andFig. 2a–c. The simulations were in good agreement with
our data. In particular, they reproduced precisely the observed momentum-dependent linewidth broadening,which further supported the presence of theoreticallysuggested spin texture in h-YMn1-xAlxO3.

4. Discussion
Our INS data clearly show the unusual spin dynamics driven by the spin texture, but a more direct measurement of the spin texture will also be interesting. For
instance, small-angle neutron scattering may reveal thedetailed spatial profile of the texture.
References[1] Han, T.-H. et al., Nature 492, 406-410 (2012).
[2] Han, T.-H. et al., Physical Review B 94, 060409 (2016).
[3] Wollny, A., Fritz, L. & Vojta, M. Physical Review Letters107, 137204 (2011)[4] Maryasin, V. S. & Zhitomirsky, M. E. Physical Review
Letters 111, 247201 (2013).
[5] Brenig, W. & Chernyshev, A. L. Physical Review Letters
110, 157203 (2013).
[6] Park, P. et al., Nature Communications 12, 2306 (2021).
[7] Oh, J. et al., Nature Communications 7, 13146 (2016).

Figure 2.	Constant-q cuts of the INS data in Fig. 1a–c along the C–B line. Blacksolid lines are the calculated spin-wave spectra shown in Fig. 1d–f.

Pyeongjae Park1,2,3, Kisoo Park2,3, Joosung Oh2,3, Ki Hoon Lee2,3,4,5, Jonathan C. Leiner2,3,6, Hasung Sim2,3, Taehun Kim1,2,3,
Jaehong Jeong1,2,3, Kirrily C. Rule7, Kazuya Kamazawa8, Kazuki Iida8, T. G. Perring9, Hyungje Woo9,10, S.-W. Cheong11,
M. E. Zhitomirsky12, A. L. Chernyshev13, and Je-Geun Park1,2,3
1
Center for Quantum Materials, Seoul National University; 2Center for Correlated Electron Systems, Institute for Basic Science, Seoul National
University; 3Department of Physics and Astronomy & Institute of Applied Physics, Seoul National University; 4Center for Theoretical Physics
of Complex Systems, Institute for Basic Science; 5Department of Physics, Incheon National University; 6Physik-Department, Technische
Universität München; 7Australian Nuclear Science and Technology Organisation; 8Neutron Science and Technology Center, CROSS; 9ISIS
Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory; 10Department of Phys-ics, Brookhaven National Laboratory;
11
Department of Physics and Astronomy, and Rutgers Center for Emergent Materials, Rutgers University; 12Université Grenoble Alpes, CEA,
13
Department of Physics and Astronomy, University of California, Irvine

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Research and Development Highlights

Duality of Magnetic Excitations and Kondo Effect inMetallic Ferromagnet Fe3-xGeTe2
1. Introduction
For a long time, magnetism has been a mysterious
issue in condensed matter physics. Its understanding
can usually be divided into two opposite camps: thelocal-moment or itinerant picture. But in the intermediate range, where both local moments and itinerant
electrons are present, the nature of magnetism remains
elusive.
This is also the case in the van der Waals (vdW) metallic ferromagnet Fe3-xGeTe2, which can sustain tunableroom-temperature ferromagnetism down to the monolayer limit [1]. With the involvement of electronic itinerancy, the microscopic origin of its magnetism becomes
controversial. There has been contradictory evidence
from previous works, with some supporting the itinerant
picture [1, 2], while others support the local-moment
picture [3, 4]. To shed light on this question, we performed inelastic neutron scattering (INS) on high-quality
single crystals of Fe3-xGeTe2 on 4SEASONS of J-PARC.
2. Duality of magnetic excitations
Figures 1(a) and (b) show the overall profiles ofthe spin excitation spectra along two high-symmetry

directions in the (h, k) plane. There are two distinct patterns of spin excitations. First, it has been found thatspin-wave-like excitations disperse up from the zone
center and propagate toward the zone boundary in thelower panels. This fact indicates the ferromagnetic correlations in Fe3-xGeTe2. Second, we have found that thedispersive mode merges into a broad continuum above~20 meV. The fluctuation continuum has a columnlike shape and extends to high energies around the zone
boundary, as shown in the upper panels of Figs. 1(a) and (b).
The latter mode is beyond general spin waves.
Then, we consider spin-flip particle-hole (p-h) excitations within the itinerant Stoner model to accountfor such columnlike excitations. By using the densityfunctional theory (DFT) to calculate the electronic
bands [Figs. 1(c) and (d)] and considering p-h scattering[Fig. 1(e)], the calculated magnetic excitation spectraby random phase approximation (RPA) well reproduce
the observed columnlike excitations in Figs. 1(f ) and (g).
Therefore, we think that this high-energy (E) mode originates from itinerant electrons, while the low-E mode is
generated from local moments that we will discuss inthe following section.

Figure 1.	(a, b) INS results for the spin excitation spectra at 4 K, along two high-symmetry directions [1, 0] and [1, 1],
respectively. (c, d) DFT calculations of spin-up and spin-down bands in the ferromagnetic state, respectively.
(e) Schematic diagram for the p-h scattering processes via tight-binding model. Calculated bare (f ) and RPA
renormalized (g) spin excitation spectra below 100 meV.

31

Research and Development Highlights

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3. Low-E spin waves and Kondo effectFigures 2(a) and (c) show the low-E spin-wave-like
excitations at 4 K for in-plane and out-of-plane directions, respectively. No spin gap is observed. Also,
through quantitative analyses, we find that the spinwave stiffness for the two directions has a comparable
value. It suggests the three-dimensional nature of themagnetism in Fe3-xGeTe2, despite its quasi-two-dimensional vdW lattice structure.
Figures 2(b) and (d) show the low-E spin waves at
100 K. By naked-eye observations, it can be found thatthe excitations at 100 K are sharper both along the energy and momentum axes than those at 4 K, especiallyfor the in-plane directions. To further quantify this temperature effect, we plot constant-Q scans through thein-plane [Figs. 2(e) and (f )] and out-of-plane dispersions[Figs. 2(h) and (i)] at 4 and 100 K. At Q =(−0.09, 0, 2), apeak of the spin excitations can only be found at 100 K,
while at 4 K, no such peak is observed, but instead
there is a broad hump just above zero energy [Figs. 2(e)and (f )]. At Q =(0, 0, 1.7), inelastic peaks can be found at
both 4 and 100 K. The peak centers do not change obviously, but the peak becomes sharper at 100 K than at
4 K. We have used a damped harmonic oscillator (DHO)
formula to fit these data, which is often used to describe
damped spin waves [5]. By fitting, we can extract themagnon energy and damping constant (inversely proportional to the lifetime of the damped magnons) of theenergy scans for a series of Q values. We have plotted
the damping constant as a function of magnon energy
at 4 and 100 K in Figs. 2(g) and (j) for in-plane and outof-plane directions, respectively. It has been found thatthe damping constant at 4 K is larger than that at 100 K
along both directions, especially for the in-plane cuts.
These results reveal that the low-E spin waves at
100 K are more coherent than those at 4 K in Fe3-xGeTe2.
It is quite different from the effect of thermal fluctuations, which always make magnons lose correlation andcoherence upon warming. This unusual temperature
evolution can be understood when considering the
Kondo screening effect of the itinerant electrons on thelocal moments [6, 7]. In a Kondo lattice, each local moment is coupled with and screened by the surrounding
itinerant electrons. The interplay between them directly
contributes to the damping character of the spin waves
by local moments. Moreover, the Kondo screening effect by surrounding itinerant electrons is expected to be
more significant at low temperatures, and will weaken
upon warming. Then, a more coherent spin waves athigher temperatures can be expected as what we canobserve in Fig. 2.

Figure 2.	Low-E spin excitation spectra for the in-plane (a, b) and out-of-plane (c, d) directions at 4 K and 100 K, respectively. Constant-Q cuts and extracted damping constant at 4 and 100 K for in-plane (e-g) and out-of-plane (h-j)
directions.

32

MLF Annual Report 2021

4. Summary
In summary, our INS study on single crystals of Fedeficient Fe3-xGeTe2 has revealed that the spin excitation spectra are composed of a low-E collective mode
dispersing from the zone center and a columnlike continuum at the zone boundary that extends to above
100 meV. We attribute the origin of these two modes tothe ferromagnetic spin waves of the local moments andparticle-hole continuum from the scattering between
the spin-up and spin-down bands, respectively. The local spins and itinerant electrons couple with each otherthrough the Kondo effect, as evident from the unusual
temperature effect of the low-E spin-wave excitations.
Our work provides a rare example that spin-wave excitations, particle-hole continuum, and Kondo-lattice
behavior coexist in a d-electron system, and sheds lighton the understanding of magnetism in correlated electronic materials. This work was published in ref. [8].

Research and Development Highlights

References[1] Y. Deng et al., Nature 563, 94 (2018).
[2] B. Chen et al., J. Phys. Soc. Jpn. 82, 124711 (2013).
[3] X. Xu et al., Phys. Rev. B 101, 201104(R) (2020).
[4] S. Calder et al., Phys. Rev. B 99, 094423 (2019).
[5] J. Zhao et al., Nat. Phys. 5, 555 (2009).
[6] Y. Zhang et al., Sci. Adv. 4, eaao6791 (2018).
[7] M. Zhao et al., Nano Lett. 21, 6117 (2021).
[8] S. Bao et al., Phys. Rev. X 12, 011022 (2022).

Song Bao1, Wei Wang2, Yanyan Shangguan1, Zhengwei Cai1, Zhao-Yang Dong3, Zhentao Huang1, Wenda Si1, Zhen Ma4,
Ryoichi Kajimoto5, Kazuhiko Ikeuchi6, Shin-ichiro Yano7, Shun-Li Yu1, Xiangang Wan1, Jian-Xin Li1, and Jinsheng Wen1
1
National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University; 2School of Science, Nanjing Universityof Posts and Telecommunications; 3Department of Applied Physics, Nanjing University of Science and Technology; 4Institute for Advanced
Materials, Hubei Normal University; 5Neutron Science Section, Materials and Life Science Division, J-PARC Center; 6Neutron Science andTechnology Center, CROSS; 7National Synchrotron Radiation Research Center

33

Research and Development Highlights

MLF Annual Report 2021

Nontrivial Temperature Dependence of Magnetic
Anisotropy in Multiferroics Ba2MnGe2O7
1. Introduction
Spin-driven multiferroics [1] have been extensively
studied since the discovery of an enhanced magnetoelectric (ME) eﬀect in TbMnO3 [2]. Through spin-orbit
coupling (SOC), a spin order induces a change of charge
distribution, leading to emergence of electric polarization. In the spin-dependent d-p hybridization mechanism [3], hybridized d and p orbitals of magnetic ion andligand are modulated by spin states via SOC, and thisinduces an electric polarization. The relation between
the electric polarization P and the spin moment S is
described locally. The mechanism has been identiﬁed
in number of materials [3–5]. Since the direction of thelocal spin moment determines the direction of the electric polarization, magnetic anisotropy plays a key role informing a multiferroic structure [5–7]. The magnitude of
the anisotropy gives the energy scale for the control ofthe magnetism by the electric ﬁeld as well as magnetic
ﬁeld, which was tested in an åkermanite Ba2CoGe2O7 [8].
Although the temperature (T) dependence of theanisotropy gap in magnon spectrum in conventional
magnet scales by a power of the sublattice magnetic moment [9,10], it may not be the case for the multiferroics.
0.6

The change of the polarization with T aﬀects the spininteraction parameters through the d-p hybridization,
which leads to a nontrivial behavior in T dependenceof the anisotropy and low-energy spin dynamics near
the magnetic Γ point. In this study, we measured inelastic neutron scattering spectra to observe the nontrivial
temperature dependence of spin dynamics in a multiferroics Ba2MnGe2O7 using a state-of-the-art spectrometerwith ultra-high resolution [11].
2. Experimental details
The INS experiment was carried out using the nearbackscattering spectrometer DNA in J-PARC MLF [12].
The horizontal scattering plane was the crystallographic
ac plane, and the ﬁnal energy of neutrons Ef was set to2.084 meV by using Si (111) analyzer. The energy resolution was estimated to be 5.5 µeV in FWHM at an elastic
condition of incoherent scattering near Q = (1, 0, 1/2).
A dilution refrigerator was used to cool the sample to0.05 K.
3. Results and discussion
Figure 1(a) shows the INS spectrum measured at
10(a)0.05 K

(f)

2.5 K
1.8 K
0.9 K
0.05 K

Intensity (arb. units)

0.4

0.6

0.3

0.2

Intensity (arb. units)ħω (meV)

8
6
4
2

0.0

0.0
-0.5
0.0

0.0
(1, k , 1/2) (r.l.u.)
0.3

0.6

0.0

0.2 (b) 0.05 K

0.5
1.0

2.0

0
0
0.0

2.0

0.05

0.10
ħω (meV)

4.0

0.0(d) 1.8 K(c) 0.9 K

0.15

3.0

6.0

(e) 2.5 Kħω (meV)T2 mode0.1

T1 mode
0.0

-0.1

0.0

0.1

-0.1

0.0

0.1
-0.1
(1, k , 1/2) (r.l.u.)

0.0

0.1

-0.1

0.0

0.1

Figure 1.	Inelastic neutron scattering (INS) spectra. (a) False color plot of the INS spectrum measured at 0.05 K projected onto theħω-(1, k, 1/2) plane. (b)–(e) The INS spectra focused on the low-energy range measured at (b) 0.05 K, (c) 0.9 K, (d) 1.8 K and(e) 2.5 K. White solid curves are calculated dispersions. (f ) Temperature evolution of constant-q cuts at Q = (1, 0, 1/2); data
at diﬀerent temperature are vertically oﬀset. Black solid curves are the calculated magnon cross section.

34

(a)

gμB<S> Present study

Eg2

gμB<S> Ref. [13]Δħω (μeV)

120

6

SWT

Δ2

4
80
2

40
0
40

ħω (μeV)

HF

2+

160

0
(b)
Eg1

30

ΔHF
SWT

20

Δ1

10
0

SWT
2

(gμB<S>)P Ref. [4]

10

5

0
0

80
2
60
40

1

P (μC/m2)

15(gμB<S>)2 (μB2/Mn2+)

Δ1

(c)

ħω (μeV)0.05 K. Two dispersive modes with the boundary energy of 0.55 meV and with gaps 0.05 meV and 0.1 meVare clearly observed. The overall energy scale is consistent with the previous study [13]. It is remarkable thatthe two dispersive modes with ﬁnite gaps are clearly
resolved because of very good resolution of DNA
spectrometer. Anisotropy gaps (Eg) of the low- andhigh-energy modes, T1 and T2, respectively, at the magnetic Γ point, Q = (1, 0, 1/2), are identiﬁed at 36 µeV and
113 µeV. Eg of the T1 mode (Eg1) is drastically suppressedwith the increase of T as shown in Figs. 1(b)–1(e), while
Eg of the T2 mode (Eg2) is moderately suppressed. The intensities of the modes at the Γ point increase with theincreasing T according to the thermal balance factor, as
shown in Fig. 1(f ).
The T dependences of Eg2 and the sublattice moment gµB⟨S⟩ are shown in Fig. 2(a). The change of Eg2 in
the measurement range is small, and it scales as gµB⟨S⟩.
The behavior is consistent with conventional antiferromagnets, where single-ion anisotropy is dominated byquadratic forms of spin operators [9, 10]. In contrast, Eg1
in Fig. 2(b) increases continuously with the decrease ofT, and it cannot be scaled either by the sublattice moment or any power of it. This indicates that the T1 mode
is not purely magnetic dynamics of electronic spin, but
is hybridized with some other degrees of freedom.
Based on the spin-wave calculation, the gap energies of the magnetic anisotropy at the magnetic
SWT
16〈 ( ( )〉)〉2 2 (( )(2)(211++ 22++ /2)/2)
Γ-point areΔSWT
1Δ1 ∼∼16〈SWT
for the T1 mode and Δ2 ∼ 4〈 ( )〉 (2 1 + 2 ) for
the T2 mode. Here ( ) is spin nematic interaction,and it is included in the magnetic anisotropy term∑,in
. The obtained T dependence of ΔSWT
1
Fig. 2(b), however, is not consistent with Eg1, particularlyin the low T region. Here we note that a Mn atom has
a nuclear spin I = 5/2 and that the hyperﬁne coupling
between nuclear and electron spins induces a low energy gap [14] in addition to the magnetic anisotropy
gap. The energy gap induced by the hyperﬁne couplinghas no q dependence. Then the magnon dispersion rela222
2 2tion is modiﬁed;( ) = ( ) SWT(ΔHF )2+((Δ)HF )+= ( ) SWT
SWT
( pure)( ) isSWT
themagnon dispersion for Ti
wheremode (i = 1, 2) and ΔHF is the hyperﬁne gap [15]. The
two gaps Eg1 and Eg2 at Q = (1, 0, 1/2) are described as22
2) + (ΔHF )2 and 22 = ( Δ SWT) + (ΔHF )2 ,= ( Δ SWT
1
1where Δ = ( ( )/〈 ( )〉 . Here ( ) is
the paramagnetic nuclear spin susceptibility following
is the electron spin susceptibility along
Curie law,the crystallographic c direction, and A is the hyperﬁne
coupling. In order to estimate ΔHF and D, we ﬁt the

Research and Development Highlights

gμB<S> (μB/Mn )MLF Annual Report 2021

20
0

1

2
3
Temperature (K)4

Figure 2.	T he temperature dependences of gap energies
observed in INS spectra, anisotropy energies,
sublattice moment and electric polarization.
���(a) T dependences of Eg2 (red circles), ∆2 (black�F
circles), ∆ (blue circles) and sublattice moment.
���(b) T dependences of Eg1 (red circles), ∆1 (black�F
circles) and ∆ (blue circles). (c) T dependences of���∆1 (black circles), electric polarization P (orange
curve from Ref. [4]) and the second power of thesublattice moment (light green triangles).

constant-q cut in Fig. 1(f ) to the calculated magnon
cross-section. The ﬁt to the data is good as shown by
black solid curves. The T1 and T2 modes in Figs. 1(b)–1(e)are reasonably reproduced by the calculated magnon- dispersions shown by the white curves. The obtained hyperﬁne coupling constant is A = 240 kOe, and
it is consistent with Ref. [14] and the value reported
in 55Mn2+ ions in Mn-diluted ZnF2 [16]. The T1 mode is,thus, hybridized with the nuclear spin. The T dependence of ΔHF is shown in Figs. 2(a) and 2(b), and that ofΔSWT,ais shown in Fig. 2(a). T dependences of ΔSWT
1
2
scaled electric polarization P [4] and the second powerof the scaled sublattice moment (gµB⟨S⟩)2 are shown indoes not scale as (gµB⟨S⟩)2,
Fig. 2(c). We ﬁnd that ΔSWT
1
but is rather consistent with the temperature dependence of electric polarization, P. From the local relation
35

Research and Development Highlights

MLF Annual Report 2021

=Λ
between S and P, one has,[5, 6]. This rela=∑,tion leads to ℋ = ∑ ,, whereis an eﬀective interaction between the electric polarizations; = /Λ2 . By considering the structures ofthe spin and electric polarization at T < TN, we obtain
ΔSWT= 16〈 ( )〉(2 1 + 2 + /2)sin (2 ) , where1
is a parameter in the crystal structure. The fact that themagnetic anisotropy gap, ΔSWT
, is scaled by the electric1
polarization, ( ), means that P induces an emergent
magnetic ﬁeld. In addition, we notice that is T independent. Drastic T dependence of thus results fromthe change of Λ with T ; the modiﬁcation of the hybridized orbitals of Mn2+ and O2− ions with T leads to a smallchange of the energy, which is negligible in highly anisotropic system but is enhanced in the nearly isotropic
system such as the symmetric half-ﬁlled shell of Mn2+
ion, and it is probed as the change of thorough SOC.
Since the change of the hybridized d-p orbital with T explicitly aﬀects the anisotropy gap of the acoustic magnon, we call it hybridized magnon with the d-p orbital.
This is a characteristic quasiparticle of the multiferroics
originating from the hybridization of spin and orbital
momenta.
4. Conclusion
In conclusion, we found that the temperature dependence of the biaxial magnetic anisotropy energy inthe multiferroic Ba2MnGe2O7 is scaled by the electric polarization. The change of the hybridized orbitals of themetal and the ligands with the temperature determines
the spin-nematic interaction, leading to nontrivial temperature dependence of the anisotropy energy in theneutron spectrum as well as that of the spin-ﬂop ﬁeld.

In contrast, conventional single-ion anisotropy energyof easy-plane type is independent of temperature. The
eﬀect of hyperﬁne coupling between nuclear and electron spins is also observed in the low temperature region. Thorough account of this eﬀect is important for
accurate understanding of the temperature evolutionof the electronic spin gap.
References[1] Y. Tokura, S. Seki, and N. Nagaosa, Rep. Prog. Phys.
77, 076501 (2014).
[2] T. Kimura et al., Nature 426, 55 (2003).
[3] T.-h. Arima, J. Phys. Soc. Jpn. 76, 073702 (2007).
[4] H. Murakawa et al., Phys. Rev. B 85, 174106 (2012).
[5] M. Soda et al., Phys. Rev. Lett. 112, 127205 (2014).
[6] J. Romhanyi et al., Phys. Rev. B 84, 224419 (2011).
[7] S. Hayashida et al., Phys. Rev. B 92, 054402 (2015).
[8] M. Soda et al., Phys. Rev. B 94, 094418 (2016).
[9] F. M. Johnson and A. H. Nethercot, Phys. Rev. 114,
705 (1959).
[10] R. J. Birgeneau, J. Skalyo, and G. Shirane, Phys. Rev. B
3, 1736 (1971).
[11] S. Hasegawa et al.,,Phys. Rev. Research 3, L032023(2021).
[12] K. Shibata et al., JPS Conference Proceedings 8,036022 (2015).
[13] T. Masuda et al., Phys. Rev. B 81, 100402(R) (2010).
[14] A. S. Borovik-Romanov and V. Tulin, JETP Lett. 1, 134(1965).
[15] I. A. Zaliznyak, N. N. Zolin, and S. V. Petrov, JETP Lett.
64, 473 (1996).
[16] A. M. Clogston et al., Phys. Rev. 117, 1222 (1960).

S. Hasegawa1, S. Hayashida1, S. Asai1, M. Matsuura2, I. Zaliznyak3, and T. Masuda1
Institute for Solis State Physics, the University of Tokyo; 2Neutron Science and Technology Center, CROSS; 3Brookhaven National Laboratory

1

36

MLF Annual Report 2021

Research and Development Highlights

Study of a Low Temperature Crystal Structure of a New
Magnetoelectric Material
heat anomaly (Fig. 2c). Consequently, Mn3Ta2O8 involves
three phases at low temperatures: phase I (T > TS),phase II (TS > T > TN), and phase III (T < TN). Upon the 55 K
transition, the magnetic susceptibility does not exhibit
any anomaly (Fig. 2a), whereas the dielectric constantshows a clear kink (Fig. 2b). The electric polarization isabsent in phase II. These observations suggest that the
55 K transition is of antiferroelectric-like origin. However,
our powder x-ray diffraction measurement could not detect any change in the crystal structure, presumably due
to a tiny structural change. Thus, the origin of this newphase transition remains unsolved.
Here we carry out high-resolution powder neutron
diffraction experiments to elucidate the crystal structurein phase II and hence the origin of the 55 K transition in
Mn3Ta2O8.
2. Methods
To obtain a high-quality powder sample, we firstprepared single crystals of Mn3Ta2O8 by a floating-zone
method [4]. An impurity phase was observed in the

M/B(emu per mol-f.u.)

1. Introduction
The coupling between magnetic and electric dipole degrees of freedom (magnetoelectric coupling) ininsulating quantum materials enables us to manipulatemagnetism by an electric field and dielectricity by amagnetic field, which may contribute to the design ofnovel functional devices. Continued efforts have been
made to explore new types of magnetoelectric couplings and materials.
Mn3Ta2O8 has an anion-deficient fluorite-related
crystal structure with centrosymmetric tetragonal spacegroup I41/a at room temperature (T) (see Fig. 1) [1]. It
undergoes an antiferromagnetic phase transition at
TN = 24 K (Fig. 2a), below which collinear spin arrangement emerges [2]. Recently, we predicted by symmetry
consideration that this AFM order breaks both space
inversion and time reversal symmetries, thereby inducing the linear magnetoelectric effect [3], and confirmed
this prediction by electric polarization measurements.
Furthermore, we also found a previously unknown
phase transition at TS = 55 K as evidenced by a specific

Mn3
Mn1
Mn2

0.10
0.06
0.04
55
50

b

Figure 1.	The crystal structure of Mn3Ta2O8, consisting of
Mn1O7, Mn2O8, and Mn3O4 polyhedra. The Ta ionsare omitted for clarity.

45

CP/T
2
(J per K mol-f.u.)

a

TN

B||c

II

TS

(a)

B||a

(b)

ε||a

B=0

ε||c

2

(c)
B=0

1.5
0

I

B = 0.1 T

0.08

ε

c

III

0.12

20

40

T (K)

60

80

Figure 2.	Temperature (T) dependences of (a) magnetization(M) divided by an applied magnetic field (B = 0.1 T)along the a and c axes, (b) a and c axes’ dielectric
constant ε at 0 T, and (c) heat capacity (Cp) divided
by T at 0 T (Ref. 3).

37

Research and Development Highlights

MLF Annual Report 2021

outer skins of the obtained crystalline rods. The dirty
skins were mechanically removed, and the left portions
were confirmed to be phase-pure single crystals of
Mn3Ta2O8. The powder sample was obtained by crushing the single crystals.
Time-of-flight neutron diffraction measurements
were carried out on a powder sample of Mn3Ta2O8 using a powder diffractometer SuperHRPD on BL08 [5].
The crystal structure was refined using Z-Rietveld software [6]. VESTA software was used to draw the crystal
structures in this report [7].

142
104

0.7

30 K
60 K

430

Intensity
Intensity (arb. units)

3. Results and discussions
Figure 3 shows diffraction patterns at 30 (phase II)
and 60 K (phase I) in a specific d region. It is seen thattiny but detectable peaks newly appear at 30 K. The
new peaks can be indexed in the tetragonal notation
as hkl (h+k+l = 2n+1). The body-centered symmetry of
the I41/a space group is thus broken in phase II.
As mentioned above, the electric polarization is absent in phase II. This indicates that the crystal structureof phase II belongs to a nonpolar space group. There are
four nonpolar space groups (P-4, P2/a, P21/a, and P-1)
that are the subgroups of I41/a (The c axis is taken as
the unique axis of P2/a and P21/a). Among them, weconsider that P21/a is most reasonable for the following
reasons. In the parent I41/a structure, the site symmetryof all ions is 1, except for -4 of Mn2 and Mn3 ions. It isthus likely that a lowering of the site symmetry of Mn2
and Mn3 due to off-center displacements is responsible for the antiferroelectric-like ordering in phase II. The
possibility of P-4 and P2/a can be excluded because offcenter displacements in this case are allowed only along

0.6

2.24

2.28

2.32

d (Å)
d / Angstrom

2.36

2.40

Figure 3.	Time-of-flight powder neutron diffraction patterns
at 30 K (red) and 60 K (black) (Ref. 3). The arrows indicate new peaks appearing at 30 K.

38

the tetragonal c axis, which is inconsistent with the factthat the dielectric anomalies at 55 K appear in both thea and c axes (Fig. 2b). For P21/a and P-1, by contrast,
the site symmetry of Mn2 and Mn3 is 1, allowing thedisplacement along any direction, consistent with theobservations. Moreover, no peaks were observed that
violate extinction rules for P21/a. Thus, although the possibility of P-1 cannot be excluded, the higher-symmetry
P21/a seems to be the most appropriate choice.
Based on P21/a, we refined the 30 K crystal structureusing the Rietveld method. We achieved good agreement between the observed and calculated patterns(χ2 = 2.17, Rwp = 2.27%, Rp = 1.87%, and Re = 1.54%). It
has been found from the refinement that Mn2 exhibitsa small but finite off-center displacement, whose direction is illustrated in Fig. 4. The resulting changes in the
Mn2-O bond lengths are smaller than 0.2 Å. The component of the displacement is finite along both the a and caxes, in agreement with the emergence of the dielectricanomalies both along the a and c axes. Such a displacement is not observed for Mn3. These results show that
the Mn2 off-center displacement plays a key role for the
antiferroelectric-like ordering at 55 K.
It is worthy to note that the Mn2+ ion has nonempty
d orbitals (d5). In the common ABO3 perovskite oxide
ferroelectrics such as BaTiO3, the ferroelectricity is usually
driven by the off-center displacement of the B site cation having a d0 configuration. This so-called “d 0-ness” excludes the magnetism that needs nonempty d orbitals [8].
However, a recent statistical structural analysis [9] ofvarious Fe3+ oxides demonstrated that the second order
Jahn-Teller (SOJT) effect, which leads to the off-center
displacement of d0 cations, is also allowed for high-spin

Figure 4.	The Mn2 off-center displacements at 30 K (phase II),
whose direction is denoted by the green arrows(Ref. 3).

MLF Annual Report 2021

d5 cations because they have the same electronic symmetry. Thus, the Mn2+ (d5) off-center displacements in
Mn3Ta2O8 can be explained by the SOJT effect.
4. Conclusion
By means of high-resolution powder neutron diffraction measurements, we have studied the origin of
the new antiferroelectric-like ordering in the magnetoelectric compound Mn3Ta2O8. We have found thatthe off-center displacement of magnetic Mn2+ ions is
responsible for the antiferroelectric-like ordering. The
present study reveals that Mn3Ta2O8 is a new system
where Mn2+ ions carry both magnetic and electric dipole
degrees of freedom.

Research and Development Highlights

References[1] S. Esmaeilzadeh et al., J. Mater. Chem., 8 2493 (1998).
[2] J. Grins et al., J. Mater. Chem., 9 1575 (1999).
[3] K. Kimura et al., Inorg. Chem., 60 15078 (2021).
[4] K. Rickert et al., Inorg. Chem., 54 6513 (2015).
[5] S. Torii et al., J. Phys.: Conf. Ser. 503 012052 (2014).
[6] R. Oishi et al., Nucl. Instrum. Methods Phys. Res.,
Sect. A, 600 94 (2009).
[7] K. Momma and F. Izumi, J. Appl. Crystallogr., 44 1272
(2011).
[8] N. Hill, J. Phys. Chem., 104 6694 (2000).
[9] J. Cumby and J. P. Attfield, Nat. Commun. 8 14235(2017).

K. Kimura1, N. Yagi1, M. Hagihala2,3, and T. Kimura1
Department of Advanced Materials Science, University of Tokyo; 2Institute of Materials Structure Science, KEK; 3Materials Science ResearchCenter, Japan Atomic Energy Agency

139

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MLF Annual Report 2021

Crystalline Electric Field in Non-Centrosymmetric CeTX3
1. Introduction
In recent years, the influence of inversion symmetry
breaking on physical properties has become one of themost attractive fields of research. In the CeTSi3 (T = transition metal) system, anomalously high upper criticalfield Hc2 behavior has been reported due to Cooper pairmixing in the superconducting state [1–4]. More recently, it has been theoretically predicted that the reentrant
superconducting behavior of UTe2 is realized by local
inversion symmetry breaking around uranium [5, 6]. In
addition, topology due to inversion symmetry breaking plays an important role in the physical properties
not only in the bulk but also at surfaces and interfaces,such as the anomalous Hall effect observed in magnetic
skyrmions.
In the broken inversion symmetry system, antisymmetric spin-orbit interaction (ASOI) is expected to play
an important role in the physical properties. The ASOI
lifts the degeneracy of electronic states in momentum
space without magnetic fields. The splitting width of theelectronic band is about ~1000 K [7], and the significant
change in the electronic state due to the effect of ASOI
is expected to affect the magnetic properties.
CeTSi3 is a tetragonal structure with space group
I4mm and it breaks the inversion symmetry along theinterplane direction. In these compounds, there aredifferences in physical properties such as CeRhSi3 [1]and CeIrSi3 [2], which exhibit superconductivity underpressure, and CePdSi3 [8] and CePtSi3 [9], which exhibit
multiple metamagnetic transitions. In addition, superconductivity has also been reported in isostructural
CeTGe3. Therefore, we investigated the difference inphysical properties by determining their crystalline electric field (CEF) level schemes by inelastic neutron scattering (INS) experiments and discussed the anomalous
superconducting properties.
2. Experimental procedure
Polycrystalline samples of CeTSi3 were grown byarc melting. The polycrystalline samples were cut into
thin strips and glued to aluminum plates to reduce neutron absorption. INS experiments were carried out with
non-magnetic and isostructural lanthanum compounds
using High Resolution Chopper spectrometer (HRC) installed at BL12 in J-PARC MLF. The sample was cooled to
3.0 and 4.2 K, and the INS spectra were acquired with anincident energy of Ei = 72 meV (CeRhSi3) and 153 meV(CeIrSi3).
3. Results and discussion
The magnetic scattering of CeTSi3 was extracted
by subtracting the measurement data of non-magnetic LaTSi3 from the results of the INS data for CeTSi3.
Figures 1(a) and 1(b) show the magnetic scattering of

Figure 1.	Color-coded plots of the magnetic INS intensity for (a) CeRhSi3 and (b) CeIrSi3. One-dimensional cut-out of (c) CeRhSi3 and(d) CeIrSi3. Dashed lines show the elastic scattering, the quasi-elastic scattering, and CEF excitations. The vertical bars represent statistical errors. Schematic illustration of the CEF eigenenergies and eigenstates of (e) CeRhSi3 and (f ) CeIrSi3 [10].

40MLF Annual Report 2021

CeRhSi3 with incident neutron energy of Ei = 72 meV and
CeIrSi3 with Ei = 153 meV, respectively. Here, the verticalaxis represents the energy transfer and the horizontal
axis represents the scattering vector, respectively. We
can easily find the CEF excitations marked in yellow
in these figures. Figures 1(c) and 1(d) show the onedimensional cut-out after subtracting the effects of the
background and phonons of CeRhSi3 and CeIrSi3, respectively, and black solid lines show the fitting results with
the CEF model. The tetragonal CEF Hamiltonian withpoint group C4v is given by the three CEF parameters
00
4
2 , 4 , and
4 . In CeRhSi 3 , the fitting results show
the presence of CEF excitations centered at 19.2
and 34.6 meV with CEF parameters of 02 = 5.32 K,0
4
4 = 0.476 K, and 4 = 6.70 K. On the other hand, theCEF excitations of CeIrSi3 exist around 23.9 and 40.7 meVwith CEF parameters of 02 = 1.49 K, 04 = 0.33 K, and4
4 = 6.61 K. Furthermore, the calculated magnetic susceptibility using the CEF parameters obtained fromthese INS experiments explains well the experimentally observed behavior above the Kondo temperature.
Therefore, from these results we determined revised
and accurate CEF level schemes of CeRhSi3 and CeIrSi3
as shown in Figs. 1(e) and 1(f ).
Table 1 summarizes the properties of CeTX3. This
table shows that CeTX3 can be categorized into three

Table 1.	Physical properties of CeTX3. The 2nd column is theorientation of magnetic moment in the magnetically ordered state. The 3rd column indicates thepresence of superconductivity. The 4th column indicates the wave function of the ground state [10].

Research and Development Highlights(1)

groups, and that the ground state of Γ7 is a necessary
condition for superconductivity to appear. The two
ground states differ in the spread of the wave function,
as can be seen in Ref. 10. The wave function of Γ6 shows
an extended shape along the [001] direction, making
it difficult for it to hybridize with the orbits of other el(1)ements. In contrast, the wave function of Γ7 shows athree-dimensional spread, and possibly hybridizes withother orbits. Thus, a hybridization of the three-dimensional extended wave function of Ce3+ ions is suggested
to be responsible for the appearance of superconductivity due to the f-electron band.
The double circles of superconductivity in Table 1
indicate that the upper critical field exceeds both Pauliand orbital-limiting fields. The behavior exceeding thetwo limits is explained by the hybridization of Cooper
pairs. However, a lack of inversion symmetry generally
disfavors the formation of spin triplet Cooper pairs. For
hybridization to be realized under these conditions, thed-vector of Cooper pair and the orientation of ASOI mustbe parallel. Here, Table 1 shows that the orientation of
the magnetic moment in the ordered state is different
for CeTSi3, which exceeds two limits, and CeTGe3, which
exceeds only the Pauli-limit. In this crystal structure, theorientation of ASOI is in the in-plane direction. Therefore,
it is suggested that the magnetic fluctuations in CeTSi3
with the magnetic moment in the a-axis are predominantly responsible for the formation of spin-triplet
Cooper pairs, resulting in anomalous superconductivity.
References[1] N. Kimura et al., Phys. Rev. Lett., 95 197001 (2007).
[2] R. Settai et al., J. Phys. Soc. Jpn., 77 073705 (2008).
[3] M. Sigrist et al., J. Magn. Magn. Mater., 310 536(2007).
[4] S. Fujimoto, J. Phys. Soc. Jpn., 76 051008 (2007).
[5] S. Ran et al., Nat. Phys., 15 1250 (2019).
[6] M. H. Fischer et al., arXiv, 2204.02449.
[7] T. Kawai et al., 77 064717 (2008).
[8] D. Ueta et al., J. Phys. Soc. Jpn., 85 104703 (2016).
[9] D. Ueta et al., J. Phys. Soc. Jpn., 90 064712 (2021).
[10] D. Ueta et al., J. Phys. Soc. Jpn., 90 104706 (2021).

D. Ueta1,2,3, T. Kobuke3, H. Shibata3, M. Yoshida3, Y. Ikeda4, S. Itoh1,2, T. Yokoo1,2, T. Masuda3,2, and H. Yoshizawa3
Neutron Science Section, Materials and Life Science Division, J-PARC Center; 2Institute of Materials Structure Science, KEK; 3Neutron
Science Laboratory, Institute for Solid State Physics, The University of Tokyo; 4Institute for Materials Research, Tohoku University

141Research and Development Highlights

MLF Annual Report 2021

Spin Dynamics of the Dual Isolated Antiferromagnetic
System Ba2CoTeO6
1. Introduction
Ba2CoTeO6, abbreviated as BCTO, is a trigonal complex perovskite compound [1]. The magnetic ions Co2+
occupy two different sites in the unit cell. Uniquely, it
has been reported that the two magnetic subsystems (Aand B) composed of Co2+ ions, which behave independently as a spin-1/2 triangular-lattice Heisenberg antiferromagnet (TLHAF) and honeycomb-lattice Ising-like
antiferromagnet (HLIAF), respectively [2, 3]. The phasetransitions at TN1 = 12 and TN2 = 3 K observed by specificheat measurements correspond to long-range orders
in subsystems B and A, respectively [2]. In magnetization measurements, the magnetization curve of BCTO isgiven by the sum of those for the two subsystems. This
study shows that magnetic excitation can also be thesuperposition of those two subsystems [4].
In spin-1/2 TLHAF studies, the results of Ba3CoSb2O9
abbreviated as BCSO, one of the best experimental
realizations of a spin-1/2 TLHAF, have provided many
insights. In recent years, much attention has been
paid to magnetic excitations in BCSO [5–7]. The magnetic excitation spectrum of the ordered state of BCSO
shows a roton-like minimum in the dispersion curveat the M point (the center of the edge in the Brillouinzone), which is much different from the linear spin wave
theory (LSWT), in contrast with a dispersion maximum
predicted by the LSWT. It has been interpreted that theroton-like minimum is caused by the coupling between
a single magnon excitation and a continuum of fermionic spinons [8–10] or two magnons [11].
The structured excitation continuum in BCSO appears in the high-energy spectrum. These excitations
have a strong intensity that cannot be explained as a
two-magnon continuum [12]. This phenomenon has
been reproduced computationally by tensor-network
calculation [13], bond operator theory [14], and bosonicspinon-based analysis [15]We must pay attention to the material-specific interactions in BCSO, even if they are small. For example,
there is a discussion of the effect on magnetic spectra
concerning easy-plane anisotropy and interactions between triangular layers [11]. It is essential to measure themagnetic spectra of other systems and extract universal
features in spin-1/2 TLHAFs.

42

2. Experimental details
Inelastic neutron scattering experiments were performed on BCTO using the cold-neutron disk chopper
spectrometer AMATERAS (BL14) [16]. The BCTO crystals were grown by the BaCl2 flux method, according
to Ref. [2]. The hexagonal plate-shaped single crystal
with dimensions of 2 × 2 × 0.3 mm3 was selected. We
coaligned approximately 400 crystals on two aluminum
plates using CYTOP as glue. The data were collected at
T = 0.3, 6.0, and 20 K with incident energies Ei = 3.6, 5.6,
9.7, and 20.9 meV using a 3He refrigerator. We used thesoftware suite UTSUSEMI [17] for statistical computing.
3. Results and discussion
Figures 1 (a)-(c) show the excitation spectra of BCTO
at T = 0.3, 6.0, and 20 K. Across two magnetic transitions, the change in the magnetic spectra was partial.
The change in the low-energy excitation part of themagnetic spectra (< 5 meV) occurs between T = 0.3 and
6.0 K, while the high-energy excitation part (5–7 meV)changes between T = 6.0 and 20 K. We emphasize thatthe spectrum of subsystem B, including its intensity,
does not change across the magnetic ordering of subsystem A. This result indicates that the two subsystems
are well decoupled.
Figure 2 shows the excitation spectrum of BCTO
measured with Ei = 3.6 meV, where the low-energy partis found to be in very good agreement with the excitation spectrum of BCSO, including intensity and structure.
The single magnon dispersion has roton-like minima
with energies of 1.25 and 1.55 meV at the M point. A
structured excitation continuum has been observed in
an energy range of 3–5 meV, as shown in Fig. 1(a). These
results demonstrate that the magnetic excitations of
BCTO and BCSO are less affected by material-specificproperties (especially by interlayer interactions). These
results also indicate that subsystem A of BCTO is a goodrealization of a spin-1/2 TLHAF.
The dispersion relation for subsystem B is well reproduced by the LSWT for an Ising-like honeycomb
lattice antiferromagnet (HLAF). In the Ising model, theexcitations are localized, and the dispersion relation isflat. The dispersive magnetic spectrum observed suggests a finite XY component. The dispersion relations forsubsystem B can be described by a J1-J2-J3 XXZ modelon the honeycomb lattice, including a ferromagnetic

MLF Annual Report 2021

Research and Development Highlights

Figure 1.	Excitation spectra of Ba2CoTeO6 at T = 0.3 (a), 6.0 (b), and 20 K (c) measured with the incident
energy Ei = 9.7 meV along the high-symmetry directions Q = (H, H) of the Brillouin zone, which
are shown by red line in (d). Figure (a)–(c) are reproduced from Ref. [4].

Figure 2.	Excitation spectrum of Ba2CoTeO6 at T = 0.3 K measured
with the incident energy Ei = 3.6 meV along the directions
Q = (H, H) of the Brillouin zone. This figure is reproduced from
Ref. [4].

43Research and Development Highlights

MLF Annual Report 2021

third-nearest neighbor interaction [4]. The obtained exchange parameters are useful for determining the spin
structure of subsystem B, which has been unclear in themagnetization measurements.
4. Conclusion
We have measured magnetic excitations in BCTO.
We observed a two-step change in the excitation spectrum across the two ordering transitions at TN1 and TN2for subsystems B and A, respectively. The excitation
spectrum of subsystem B is not affected by the magnetic
ordering of subsystem A, described as a spin-1/2 TLHAF.
This result demonstrates that the excitation spectrum of
BCTO is produced by the superposition of the two independent magnetic excitation spectra originating fromtwo subsystems. This indicates that the magnetic modelof BCTO is described by decoupled spin-1/2 Heisenberglike TLAF and Ising-like HLAF.
The low-energy excitation spectrum for subsystem
A is very similar to that for BCSO. Observed roton-likeminima and structured excitation continuum are common to BCTO and BCSO. This shows that the excitation
spectra of subsystem A and BCSO are universal in spin1/2 TLHAFs.
References[1] S. A. Ivanov, P. Nordblad, R. Mathieu, R. Tellgren, andC. Ritter, Dalton Trans. 39, 5490 (2010).
[2] P. Chanlert, N. Kurita, H. Tanaka, D. Goto, A. Matsuo,
and K. Kindo, Phys. Rev. B 93, 094420 (2016).
[3] P. Chanlert, N. Kurita, H. Tanaka, M. Kimata, and H.

Nojiri, Phys. Rev. B 96, 064419 (2017).
[4] Y. Kojima, N. Kurita, K. Nakajima, and H. Tanaka, Phys.
Rev. B 105, L020408 (2022).
[5] J. Ma, Y. Kamiya, T. Hong, H. B. Cao, G. Ehlers, W. Tian,
C. D. Batista, Z. L. Dun, H. D. Zhou, and M. Matsuda,
Phys. Rev. Lett. 116, 087201 (2016).
[6] S. Ito, N. Kurita, H. Tanaka, S. Ohira-Kawamura, K.
Nakajima, S. Itoh, K. Kuwahara, and K. Kakurai, Nat.
Commun. 8, 235 (2017).
[7] D. Macdougal, S. Williams, D. Prabhakaran, R. I.
Bewley, D. J. Voneshen, and R. Coldea, Phys. Rev. B
102, 064421 (2020).
[8] F. Ferrari and F. Becca, Phys. Rev. X 9, 031026 (2019).
[9] C. Zhang and T. Li, Phys. Rev. B 102, 075108 (2020).
[10] R. Verresen, R. Moessner, and F. Pollmann, Nat. Phys.
15, 750 (2019).
[11] A. L. Chernyshev and M. E. Zhitomirsky, Phys. Rev. B
79, 144416 (2009).
[12] Y. Kamiya, L. Ge, T. Hong, Y. Qiu, D. L. Quintero-Castro,
Z. Lu, H.B.Cao, M.Matsuda, E.S.Choi, C.D.Batista,
M. Mourigal, H. D. Zhou, and J. Ma, Nat. Commun. 9,2666 (2018).
[13] R.-Z. Chi, Y. Liu, Y. Wan, H.-J. Liao, and T. Xiang,
Phys. Rev. Lett. 129, 227201 (2022).
[14] A. V Syromyatnikov, Phys. Rev. B 105, 144414 (2022).
[15] E. A. Ghioldi, S.-S. Zhang, Y. Kamiya, L. O. Manuel,A. E. Trumper, and C. D. Batista, Phys. Rev. B 106,
064418 (2022).
[16] K. Nakajima et al., J. Phys. Soc. Jpn. 80, SB028 (2011).
[17] Y. Inamura, T. Nakatani, J. Suzuki, and T. Otomo, J.
Phys. Soc. Jpn. 82, SA031 (2013).

Y. Kojima1, N. Kurita2, H. Tanaka2, and K. Nakajima1,3
Materials Sciences Research Center, JAEA; 2Department of Physics, Tokyo Institute of Technology; 3Neutron Science Section, Materials andLife Science Division, J-PARC Center
1

44

MLF Annual Report 2021

Research and Development Highlights

Magnetic Excitations in Chiral-Structure Phase of Ce3Ir4Sn13
1. Introduction
In the condensed matter physics field, topological electrons have been extensively researched [1, 2].
A linear dispersion relation of electronic band with respect to momentum (Dirac/Weyl fermion) is symmetrically protected by noncentrosymmetric or chiral spacegroups of materials [3]. In particular, the Weyl–Kondo
semimetal is a new topological state because an electronic correlation effect is added to form the linear electronic band [4, 5]. It is an attractive issue to establish themechanism of topological electron formation which appear spontaneously in the process of crystal-structuretransformation.
Ce3Ir4Sn13 has been studied for the Kondo effectowing to the interaction between Ce3+ 4f 1 and conduction electrons [6, 7]. A previous X-ray diffraction study
reported the structural modulation characterized by
the wave vector qS1 = (1/2, 1/2, 0) with respect to theunit cell with a lattice constant of 9.72 Å [8]. The same
superlattice reflections were explained by the chiralstructures of Ce3T4Sn13 (T: Co and Rh) [9–11]. The specificheat of Ce3Ir4Sn13 shows phase transitions at T1 = 0.6 K
and T2 = 2.1 K [6, 12]. Recent neutron diffraction study
revealed the propagation vector qS2 = (1/4, 1/4, 1/4)
below T2, which was also attributed to the structuretransition [13]. An antiferromagnetically ordered phasecharacterized by qM = (1/2, 1/2, 2/5) was identified below T1. The magnitude of ordered magnetic moment is
considerably suppressed to the order of 0.1μB/Ce in contrast to the Ce3+ 4f 1 state. Therefore, the magnetic fluctuation is expected to be significant in Ce3Ir4Sn13 at low
temperatures. In the present study, the crystal structure

and magnetic state of Ce3Ir4Sn13 were investigated using
quantum beam scattering techniques [14].
2. Experimental procedure
Samples were synthesized using the molten Sn-flux
method [15]. Synchrotron X-ray diffraction experiments
for single crystal samples were performed using thediffractometer BL-8A of Photon Factory, High Energy
Accelerator Research Organization. Inelastic neutron
scattering (INS) measurements for polycrystalline samples were performed using the cold-neutron disk-chopper time-of-flight spectrometer AMATERAS (BL14) of theMaterials and Life Science Facility (MLF), J-PARC [16].
3. Results and analysis
The synchrotron X-ray diffraction spots indexed by
the wave vector qS1 were observed in addition to thefundamental reflections, as reported previously [9‒11].
Based on the structural refinement using the WinGX
software suite (Sir2014 and SHELX) [17], we establishedthe chiral cubic structure with the space group I213 witha lattice constant of 19.44 Å, as depicted in Fig. 1. The
Ce-ion sites split into two inequivalent Wyckoff sites
shown by blue and green circles.
We conducted INS measurements to reveal the
crystalline-electric-field (CEF) splitting levels of the Ce
4f electron and the magnetic dynamics. As shown by
symbols in Fig. 2, the scattering function S(E) evaluated by integrated intensities in the selected scatteringvector magnitude Q region shows peaks at 4.5, 7.5,
and 47 meV, depicted by the yellow region. Because
these peak energy positions are independent of Q, theFigure 1.	Chiral crystal structure of Ce3Ir4Sn13, which was
drawn using VESTA [18].

45Research and Development Highlights

MLF Annual Report 2021

Figure 2.	High-energy INS spectra of Ce3Ir4Sn13 at 1.5 K measured using BL14.

peaks are attributed to CEF excitations. The point groupsymmetry at the Ce-ion site determined by the X-ray
structural analysis allows CEF split levels composed ofthree Kramers doublets. The two independent Ce ionsshown by the blue and green circles in Fig. 1 should
carry inequivalent CEF level schemes. Lines in Fig. 2 areleast-squares fitting results based on the eigenstatesolutions of the CEF Hamiltonians and the spectral calculation [19], which reproduce the measurement datawell. The obtained CEF level schemes are Γ6(2) 0 meV – Γ7
4.4 meV – Γ6(1) 46.4 meV for the Ce(A) site and Γ6(2) 0 meV– Γ7 7.3 meV – Γ6(1) 55.6 meV for the Ce(B) site. The Ce(A)site has a magnetic moment of 0.54μB along the direction of the Ce-ion column in Fig. 1, whereas that at theCe(B) site is 0.91μB within the plane perpendicular to theCe-ion column. It is noteworthy that the spectral widthsof the excitations to the first excited states are 0.18 and1.3 meV for the Ce(A) and Ce(B) sites, respectively.
Figure 3 shows low-energy S(E) at 0.6 K obtained byintegrating the intensity in the range of Q = 1.0 –1.5 Å‒1measured using the Ei = 3.44 meV setup. The data below
0.5 meV of Ce3Ir4Sn13 (filled red squares) are enhanced
more than the La3Ir4Sn13 data (open black squares), andthe difference is plotted by blue circles. The result indicates magnetic fluctuation with characteristic energyof the order of 0.1 meV associated with the CEF doublet
ground states.
4. Discussion
The broader CEF spectra at the Ce(B) site indicate
hybridization between the conduction and 4f electrons,
while the sharp spectrum at the Ce(A) site means therelatively localized 4f state. The same phenomenon was
46

observed in the isomorphic compound Ce3Co4Sn13; thus,
Ce3T4Sn13 take the electronic superlattices associatedwith the hybridized and localized Ce 4f sites under thechiral symmetry. The Kondo effect partially influences
the low-temperature electronic behavior in Ce3T4Sn13.
Magnetic ordering in Ce3T4Sn13 is significantly depressed despite the well-localized Ce(A)-site 4f electrons. The ordered magnetic moment amplitude of
Ce3Ir4Sn13 is in the order of 0.1μB [13], which is less thanthe eigenvalues of magnetic moments estimated fromthe CEF analysis. Furthermore, the Weiss temperature of
Ce3Ir4Sn13 evaluated from the Curie–Weiss fitting to themagnetic susceptibility data is –33.1 K, whereas the antiferromagnetic ordering temperature is 0.6 K. Ce3Co4Sn13
and Ce3Rh4Sn13 do not undergo a magnetic ordering
phase transition [9, 10]. These facts indicate that magnetic frustration may also play a role in the magnetization depression. The crystal structure shown in Fig. 1
comprises the columns with the nearest-neighbor Ceions and the triangular lattice connections via the second neighbors. Such a triangular structure is expected
to mediate geometrical frustration. Furthermore, theDzyaloshinskii–Moriya (DM) interaction caused by thelack of inversion symmetry in the chiral structure maycompete with RKKY interactions, which gives rise to frustration of interactions.
5. Summary and future plans
In Ce3Ir4Sn13, the Ce ions characterized by the c–f
hybridized state and the localized 4f electron state appear alternately in the I213 chiral structure phase. In addition, the robust magnetic fluctuation is retained evenat lower temperatures, which suggest the f electrons

MLF Annual Report 2021

Research and Development Highlights

Figure 3.	Low-energy INS spectra of Ce3Ir4Sn13 at 0.6 K measured using BL14.

contribute to the transport property. These facts indicate that Ce3T4Sn13 provides a new lattice geometry formagnetic and electronic states, which are expected torelate to the topological Weyl–Kondo state. It is a further
issue to reveal such a quantum-spin-liquid behavior andthe characteristic magnetic interactions by resolving thedetailed Q dependence of magnetic response using theneutron scattering techniques.
References[1] S. M. Young et al., Phys. Rev. Lett. 108, 140405 (2012).
[2] N. P. Armitage et al., Rev. Mod. Phys. 90, 015001(2018).
[3] J. L. Mañes, Phys. Rev. B 85, 155118 (2012).
[4] H.-H. Lai et al., Proc. Natl. Acad. Sci. U.S.A. 115, 93(2018).
[5] S. E. Grefe, et al., Phys. Rev. B 101, 075138 (2020).

[6] H. Sato et al., Physica B 186–188, 630 (1993).
[7] J. R. Collave et al., Solid State Commun. 177, 132(2014).
[8] C. Nagoshi et al., Physica B 359–361, 248 (2005).
[9] Y. Otomo et al., Phys. Rev. B 94, 075109 (2016).
[10] K. Suyama et al., Phys. Rev. B 97, 235138 (2018).
[11] J. Welsch et al., Phys. Rev. Mater. 3, 125003 (2019).
[12] S. Takayanagi et al., Physica B 199–200, 49 (1994).
[13] S. Nakazato et al., JPS Conf. Proc. 30, 011128 (2020).
[14] K. Iwasa et al., J. Phys. Soc. Jpn. 90, 124701 (2021).
[15] G. P. Espinosa, Mater. Res. Bull. 15, 791 (1980).
[16] K. Nakajima et al., J. Phys. Soc. Jpn. 80, SB028 (2011).
[17] L. J. Farrugia, J. Appl. Crystallogr. 32, 837 (1999).
[18] K. Momma and F. Izumi, J. Appl. Crystallogr. 41, 653(2008).
[19] W. Marshall and R. D. Lowde, Rep. Prog. Phys. 31, 705(1968).

K. Iwasa1,2, S. Nakazato2, D. Hashimoto2, M. Shiozawa2, K. Kuwahara2, H. Sagayama3, S. Ohira-Kawamura4, N. Murai4, D. T. Adroja5,6,
and A. M. Strydom6
1
Frontier Research Center for Applied Atomic Sciences & Institute of Quantum Beam Science, Ibaraki University; 2Graduate School of Scienceand Engineering, Ibaraki University; 3Institute of Materials Structure Science, High Energy Accelerator Research Organiza-tion; 4Neutron
Science Section, Materials and Life Science Division, J-PARC Center; 5ISIS Facility, Rutherford Appleton Laboratory; 6Physics Department,
University of Johannesburg

47Research and Development Highlights

MLF Annual Report 2021

Two-Dimensional Ferromagnetism at Topological Surfaceof FeSi Observed by Polarized Neutron Reflectometry
1. Introduction
Two-dimensional (2D) quantum materials [e.g., surfaces of topological insulators (TI) and atomic layer devices exfoliated from van der Waals (vdW) crystals] haveattracted significannt attention. Their unique properties,
such as energy dissipation-free conduction of charges
and spins in magnetic TI [1] and emergence of versatilequantum states in vdW heterostructures [2], are expected to open a new era of electronics on the atomic scale.
Turning to spintronics applications in those 2D
quantum materials, strong spin-orbit coupling (SOC)
inherent in the heavy elements plays a central role. For
example, strong SOC induces the band inversion necessary for topological electronic states, leading to spinmomentum locked metallic states at the surface. These
spin-orbit coupled surfaces are the source of high-performance spintronic functionality, forming the basis forapplications in next-generation power-saving electronic
devices.
On the other hand, those heavy elements are generally scarce and toxic, and it is desirable to reduce theirconsumption from the viewpoint of resources and theenvironment. The ferromagnetic and spintronic properties of the topological surface of FeSi revealed in thisstudy may be an important key to facilitate realistic device applications of 2D quantum materials [3].
The chiral compound FeSi has long been known as anonmagnetic insulator with strong electron correlations[4]. Many of its unusual electronic and spin properties
have been identified, such as large magnetic susceptibility at high temperature [5] and insulator-metal crossoverat low temperature (T ~ 200 K) [6].

Figure 1.	Visualized eigenfunction of the ferromagnetic metal state at FeSi(111) surface.

48

Recently, those peculiar properties of FeSi havebeen re-examined from a topological aspect. In thisstudy, we successfully identified the emergence of aferromagnetic-metal surface state in FeSi [3]. We also
found that FeSi surface exhibits strong SOC properties
as in the case of topological insulators, despite the factthat FeSi is composed of light elements with relatively
small atomic numbers. The FeSi surface exhibits a large
Rashba-type spin splitting (~ 40 meV), which enables
the current-induced magnetization switching throughspin-orbit torque.
Although our first-principles calculations predicted that this unique surface state exists in only a few
atomic layers (Fig. 1), it had been difficult to experimentally identify and quantitatively evaluate the 2D
ferromagnetism using magnetization and conductivity
measurements. Here we could directly observe the ferromagnetic surface state of FeSi by polarized neutronreflectometry.
2. Experiments
Polarized neutron reflectometry (PNR) measurements were carried out at BL17 (SHARAKU) in the
Materials and Life-science Experimental Facility of
J-PARC in Japan [7]. The PNR measurements were performed on MgO(4 nm)/FeSi(11 nm) heterostructure at
T = 7 K and under an in-plane magnetic field μ0H = 1 T.
The areal size of the sample was approximately 15 mm ×
15 mm. The FeSi layer was grown epitaxially along [111]direction on a Si(111) substrate, while the MgO capping
layer was deposited in an amorphous form. The incident
neutron beams with a wavelength band of 2.2–8.8 Å
were polarized either spin-up (+) or spin-down (–) withrespect to H-direction. The polarized neutrons were reflected by the film in a specular geometry as shown in
Fig. 2(a). The reflectivity for polarized neutrons (R + or R –)was measured without polarization analysis, because
the spin-flip scatterings were not expected for the fully-magnetized state. The depth profiles of nuclear andmagnetic scattering length densities (SLD), which respectively correspond to the density distributions of theconstituent elements and the magnetic moments, werededuced through model fitting to the PNR spectra byusing GenX software [8]. Here we set layer thicknesses,
densities, surface/interfacial roughness and magnetic
moments as the fitting parameters.

MLF Annual Report 2021

3. Results and discussions
The reflectivity curves of R+ and R – as functions of
the momentum transfer normal to the surface Qz isshown in Fig. 2(b). A clear difference between R+ andR – represents the existence of finite net magnetizationin the film. By comparing the fidelity of candidate models assuming surface-, interface- or bulk-magnetization
distributions, we identified that the magnetization was
confined only at the top surface of FeSi in contact with
the MgO capping layer. The depth profiles of nuclear
and magnetic SLD were deduced by optimizing the fitting parameters [Fig. 2(c)]. The fitting analysis concluded
that the surface ferromagnetic layer had a thickness of
0.35 nm (with an error of +0.11 nm or –0.13 nm) andan average of 2.1 μB/Fe (with an error of +0.4 μB/Fe or–0.6 μB/Fe), whose distribution is blurred by the crystalline roughness of 0.28 ± 0.02 nm, as schematically illustrated in the inset of Fig. 2(a). This result is consistent

Research and Development Highlights

with the calculated surface ferromagnetic state consisting mostly of the magnetic moments of the top three
Fe layers.
4. Summary
We have succeeded in directly observing the 2D ferromagnetic state confined in the surface atomic layersof FeSi by PNR. The thickness of the ferromagnetic state
was estimated to be approximately 0.35 nm, which is ingood agreement with the prediction from first-principles calculations. Our demonstration may facilitate thedesign of environmentally-friendly topological materials
consisting of common elements. High-resolution PNR
will attract renewed attention as an important measurement technique since a variety of quantum states arebeing realized in complex heterostructures of topological materials and 2D quamtum materials.
References[1] Y. Tokura, K. Yasuda and A. Tsukazaki, Nat. Rev. Phys.,
1 126 (2019).
[2] A. K. Geim and I. V. Grigorieva, Nature, 499 419(2013).
[3] Y. Ohtsuka, N. Kanazawa, M. Hirayama et al., Sci.
Adv., 7 eabj0498 (2021).
[4] M. Imada, A. Fujimori and Y. Tokura, Rev. Mod. Phys.,
70 1039 (1998).
[5] V. Jaccarino et al., Phys. Rev., 160 476 (1967).
[6] Z. Schlesinger et al., Phys. Rev. Lett., 71 1748 (1993).
[7] M. Takeda et al., Chinese J. Phys., 50 161 (2012).
[8] M. Björck and G. Andersson, J. Appl. Cryst., 40 1174
(2007).

Figure 2.	Direct observation of the ferromagnetic (FM) surface
state of FeSi by polarized neutron reflectometry (PNR).
(a) Schematic illustration of the experimental setup.
The surface spins (red arrows) are aligned along the external in-plane magnetic field. (b) Measured (dots witherror bars) and fitted (solid lines) reflectivities of polarized neutrons with spin-up and spin-down (R + and R −)at T = 7 K and at μ0H = 1 T. (c) Estimated depth profilesof the nuclear (black line) and the magnetic (red line)
scattering length densities (SLD).

N. Kanazawa1, Y. Ohtsuka1, T. Nakajima2,3, T. Hanashima4, V. Ukleev5,6, H. Aoki7,8, and Y. Tokura9
Department of Applied Physics, University of Tokyo; 2Institute for Solid State Physics, University of Tokyo; 3RIKEN Center for Emergent
Matter Science (CEMS); 4Neutron Science and Technology Center, CROSS; 5Laboratory for Neutron Scattering and Imaging (LNS), Paul
Scherrer Institute (PSI); 6Helmholtz-Zentrum Berlin für Materialien und Energie; 7Materials and Life Science Division, J-PARC Center;
8
Institute of Materials Structure Science, High Energy Accelerator Research Organization; 9Tokyo College, University of Tokyo

1

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MLF Annual Report 2021

Ferromagnetic Hysteresis Induced by Vortices in a
Magnetic Superconductor EuRbFe4As4
1. Introduction
Superconductivity and magnetism, which in general compete with each other, sometimes coexist in amaterial. Such a material is called magnetic superconductor. It has been demonstrated that the interplay
between superconductivity and magnetism induces
numerous exotic phenomena, such as the reentrant
superconducting transition associated with the suppression of superconductivity around the magnetictransition temperature (Tm), highlighting the impact ofmagnetism on superconductivity. The discovery of newmagnetic superconductors has played an important rolein the study of the interaction between superconductivity and magnetism. Recently, iron-based superconductors which contain Eu as a constituent element (Eu-IBSs)
have attracted much attention as a new class of magnetic superconductors [1]. EuRbFe4As4 [2, 3] has the highest
superconducting critical temperature (Tc ~ 37 K) among
the Eu-IBSs and shows a helimagnetic order (Tm ~ 15 K)
at the ground state (Fig. 1(a)) [4]. The known superconducting properties of IBSs should ensure a strong vortex
pinning capability in EuRbFe4As4 that results in strong
magnetic fields which possibly influence the magnetismof Eu2+ moments. Thus, in order to investigate the influence of superconductivity on magnetism in EuRbFe4As4,
we performed neutron diffraction measurements undermagnetic fields [5].

2. Experiments
Single crystals of EuRbFe4As4 were grown by the
RbAs-flux method [5, 6]. The surfaces of as-grown crystals were carefully cleaved to remove the RbFe 2As 2phase. X-ray diffraction (XRD) patterns were measured
at room temperature using a diffractometer with Cu
Kα radiation (Rigaku, Ultima IV) to verify the presenceof 00l peaks of EuRbFe4As4. Single-crystal neutron diffraction measurements on EuRbFe4As4 were carried out
using the time-of-flight (TOF) single-crystal neutron
diffractometer SENJU [7] installed at the Materials andLife Science Experimental Facility (MLF), Japan Proton
Accelerator Research Complex (J-PARC). The sample
size was 1.8 × 0.9 × 0.08 mm3. A neutron wavelengthof 0.4–4.4 Å was used. The magnetic field was appliedalong the [110] direction of EuRbFe4As4 up to 2 T. The
data were visualized by the software STARGazer [8].
3. Results and discussion
Figure 1(b) shows the neutron diffraction patterns
along the (00L) direction of EuRbFe 4As 4 measured
at 2.5 K, well below Tm. First, in the zero-field cooled(ZFC) condition (blue), diffraction peaks are observed
at (00L ± 0.25) positions in addition to (00L) positions.
The (0, 0, 0.25) magnetic propagation vector indicatesthat the direction of the Eu2+ moments rotates by 90°
between neighboring layers, i.e. the helical structure(Fig. 1(a)). With an increasing magnetic field, at 0.4 T

Figure 1.	(a) Crystal structure of EuRbFe4As4. The light blue arrows indicate the direction of the Eu2+ moments in the helically orderedstate. (b) Neutron diffraction patterns of EuRbFe4As4 along (00L) at 2.5 K and 0 T (ZFC), 0.4 T, as well as 0 T after applying afield of 2 T. (c) Magnetic field dependence of peak intensity for (001.25) peak (blue) and (001) peak (green). The peak intensity is normalized at 0 T (ZFC) and 2 T for the (001.25) and (001) peaks, where the Eu2+ moments are completely helical andferromagnetic, respectively. Arrows indicate the field sweep direction.

50

MLF Annual Report 2021

(green), the (00L ± 0.25) peaks almost disappear, while
the intensity of the (00L) peaks is enhanced. The results
demonstrate the transition of the Eu2+ magnetic orderfrom a helical to a ferromagnetic arrangement.
Then, the field was decreased from value 2 T, whichis large enough to completely align the Eu2+ moments
ferromagnetically. The diffraction pattern at zero field
after applying 2 T (red) is found to be almost identicalto that at 0.4 T. Although the peak at (001.25) can stillbe identified, its intensity is smaller by about one orderof magnitude than that at increasing field. The results
show that the Eu2+ moments do not return to the initialhelical structure but remain mostly in the ferromagnetic
arrangement even at zero field.
The magnetic field dependence (–0.4 T ≤ μ 0H ≤ 0.6 T)of the intensity of the (001.25) peak (blue) and the (001)peak (green) is summarized in Fig. 1(c). Each intensity
represents the fraction of helical and ferromagnetic
structure, respectively. One can see that the intensitiesof the (001) and (001.25) peaks are inversely correlated,suggesting that the fraction of intermediate structureis small. Notably, the (001.25) peak is slightly enhanced
just after field reversal. Thus, the neutron diffraction
measurements revealed a characteristic ferromagnetic
hysteresis of the Eu2+ moments in EuRbFe4As4.
Because the hysteresis of the Eu 2+ moments in
EuFe2As2 (a related non-superconducting compound) is
negligibly small [9], the ferromagnetic hysteresis is likely
induced by superconductivity. Thus, we propose a model that the direction of the Eu2+ moments is determinedby the distribution of pinned vortices in the sample [5]Research and Development Highlights

as illustrated in Fig. 2. Indeed, the experimental results
can be reasonably reproduced by the model where thelocal magnetic field distribution created by vortices iscalculated based on the Bean’s critical state model [10].
4. Conclusion
We performed single-crystal neutron diffraction measurements on the magnetic superconductor
EuRbFe4As4 which shows a high-Tc superconductivity
and a helical magnetic order. We revealed a ferromagnetic hysteresis of the Eu2+ moments induced by the superconducting vortices. The unique interaction between
local moments and vortices could be used to manipulate the spin texture, showing the potential for novel
device applications of EuRbFe4As4.
References[1] S. Zapf and M. Dressel, Rep. Prog. Phys. 80 016501(2017).
[2] K. Kawashima et al., J. Phys. Soc. Japan 85 064710(2016).
[3] Y. Liu et al., Phys. Rev. B 93 214503 (2016).
[4] K. Iida et al., Phys. Rev. B 100 014506 (2019).
[5] S. Ishida et al., Proc. Natl. Acad. Sci. USA 118
e210110118 (2021).
[6] J. K. Bao et al., Cryst. Growth Des. 18 3517 (2018).
[7] T. Ohhara et al., J. Appl. Cryst. 49 120–127 (2016).
[8] T. Ohhara et al., Nucl. Instrum. Methods Phys. Res. A
600 195 (2009).
[9] S. Jiang et al., New J. Phys. 11 025007 (2009).
[10] C. P. Bean, Rev. Mod. Phys. 36 31 (1964).

Figure 2.	Schematic illustration of ferromagnetic hysteresis of the Eu2+ moments induced bysuperconducting vortices pinned in the EuRbFe4As4 sample.

S. Ishida1, D. Kagerbauer2, S. Holleis2, K. Iida3, K. Munakata3, A. Nakao3, A. Iyo1, H. Ogino1, K. Kawashi-ma4, M. Eisterer2, and H. Eisaki1
1Research Institute for Advanced Electronics and Photonics, AIST; 2Atominstitut, TU Wien; 3Neutron Science and Technology Center, CROSS;
4
Research & Development Department, IMRA JAPAN CO., LTD.

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MLF Annual Report 2021

Muon-Induced Soft Errors in 20-nm SRAMs: Similarities
and Differences with Neutrons and Alpha Particles
1. Introduction
Soft errors are radiation-induced transient errors
in semiconductor devices, which degrade the dependability of electronic systems. The continuous scaling of
CMOS technologies has made the devices more susceptible to soft errors. In the terrestrial environment, neutrons and alpha particles have been known as the major
sources of the soft errors. The neutrons are part of thesecondary cosmic rays. The alpha particles are emitted
from radioactive impurities naturally present in the device materials.
In recent years, muons have attracted increasing attention as a potential source of the terrestrial soft errors.
One reason for this is that scaled semiconductor devices
are vulnerable to low-linear energy transfer (LET) particles. Another reason is that the muons are the mostabundant particles in secondary cosmic rays, where
negative and positive muons are produced. Despite thisincreased risk, there have been only a few experimental
studies on the muon-induced soft error [1, 2]. Therefore,
further investigation is needed for understanding theircharacteristics.
This work investigates muon-induced soft errors
in static random-access memories (SRAMs) fabricatedin a scaled 20-nm bulk planar CMOS technology [3].
Irradiation experiments are performed using negativeand positive muon beams. The unique characteristicsof the muon-induced soft errors are analyzed throughcomparison with neutron- and alpha-induced ones.
2. Irradiation experiments
Particle irradiation tests were conducted for negative muons, positive muons, high-energy neutrons,
thermal neutrons, and alpha particles, as summarizedin Table 1. The negative and positive muon irradiations
were performed using monoenergetic beams at themuon science facility (MUSE), J-PARC [4]. The high-energy neutron irradiation was performed using a spallation
neutron beam at the Research Center for Nuclear Physics(RCNP), Osaka University [5]. The thermal neutron irradiation was performed using a neutron irradiation ﬁeld
at the Heavy Water Neutron Irradiation Facility (HWNIF)of the Kyoto University Research Reactor (KUR) [6].
The alpha particle irradiation was performed using an
241
Am source in our laboratory. The energy spectra of theneutron beams were similar to the terrestrial ones, as
52

shown in Fig. 1.
The 20-nm SRAM chips were irradiated with theseparticles. In the irradiation tests, we measured the occurrence rate of single-event upsets (SEUs), which
are the most common soft errors causing the flippingof the stored data by a single particle strike. The SEU
events were categorized into two types: single-bit upsets (SBUs) and multiple-cell upsets (MCUs). The SBU
and MCU events correspond to single-bit errors andmultiple-bit errors, respectively. We note that, from areliability viewpoint, the MCU events are important tobe evaluated because they can degrade error correction
efficiency. For each irradiation test, the event cross sections (CSs) were calculated as, where, , andare the number of observed events,
the incident particle ﬂuence, and the number of SRAM
bits irradiated, respectively.

Table 1. Irradiation particles and facilities.
Irradiation particle

EnergyFacility

Negative/Positive muon

Monoenergetic

MUSE [4]High-energy neutron

Terrestrial-like

RCNP [5]Thermal neutron

Terrestrial-like

KUR [6]Alpha particle

5.4 MeV ( Am)

241

Lab.

Figure 1.	SEU CSs for negative and positive muons, high-energy and thermal neutrons, and alpha particles as afunction of supply voltage. The CSs are normalizedin each particle by the respective CS value at 0.6 V.
The muon energy is 1.02 MeV. Error bars represent
one standard error.

MLF Annual Report 2021

3. Results and discussion
The comparison of the SEU CS between the muonsand the other particles reveals similarities and differences in the supply voltage dependence, as shown in
Fig. 1. In this comparison, the muon energy was set to1.02 MeV, where the CS peak was observed, to fully capture the muon-specific characteristics [3]. For the negative muon, the voltage dependence was very similar tothat for the high-energy neutron. For the positive muon,
the CS drastically decreased with the voltage, which wasvery different from the other particles. These contrasting behaviors are due to the difference in the amountof charge deposited by the incident particles [3]. Our results indicate that the charge deposition by the negative
muons, including the secondary ions produced throughthe capture reactions, is comparable to that by the highenergy neutrons.
The comparison of the MCU ratios, which are calculated by dividing the MCU CS with the SEU CS, provided
insight into the mechanism of the negative muon-induced MCUs. As presented in Fig. 2, the slopes in the

Figure 2.	MCU ratios for negative muons, high-energy andthermal neutrons, and alpha particles as a functionof supply voltage. The values are normalized by thevalue at 0.6 V of negative muon. Error bars represent one standard error. Note that the result for the
positive muon is omitted because its MCU CS wassigniﬁcantly lower.

Research and Development Highlights

voltage dependence for the negative muon and thehigh-energy neutron were similar and slightly positive.
This indicates the significant contribution of the parasitic bipolar effect, which can be triggered by high-LET
secondary ions and tends to cause MCUs [3]. Anotherpoint was that the MCU ratio for the negative muon
was larger than that for the high-energy neutron. Thisis probably due to the difference in the secondary ion
emission. In the muon capture reactions, the secondary
ions are emitted isotropically and are thus more likely to
travel multiple SRAM cells compared to the secondary
ions produced by the high-energy neutrons. From ourresults, it is probable that the characteristics of the negative muon-induced MCUs are dominated by the natureof the muon capture reactions.
4. Future plans
To address the growing concern about the terrestrial soft errors, we continue to investigate the muoninduced soft errors in more advanced semiconductor
devices. Specifically, the impact of the change of transistor structure needs to be explored because fin-shaped
transistors, called FinFETs, are becoming widely employed instead of planar transistors used in this work.
In the case of neutrons for example, it has been demonstrated that the SEU characteristics are significantly
different between planar and FinFET SRAMs [7]. Further
understanding of the muon-induced soft errors would
be helpful in assessing and improving the dependabilityof advanced electronic systems.
References[1] W. Liao et al., IEEE Trans. Nucl. Sci., 65 1734 (2018).
[2] S. Manabe et al., IEEE Trans. Nucl. Sci., 65 1742 (2018).
[3] T. Kato et al., IEEE Trans. Nucl. Sci., 68 1436 (2021).
[4] Y. Miyake et al., Phys. Procedia, 30 46 (2012).
[5] Y. Iwamoto et al., Nucl. Technol., 173 210 (2011).
[6] Y. Sakurai et al., Nucl. Instr. Meth. A, 173 569 (2000).
[7] T. Kato et al., IEEE Trans. Nucl. Sci., 67 1485 (2020).

T. Kato1, M. Tampo2,3, S. Takeshita2,3, H. Tanaka4, M. Hashimoto5, and Y. Miyake2,3Reliability Engineering Department, Socionext Inc.; 2Institute of Materials Structure Science, KEK; 3Muon Science Section, Materials and Life
Science Division, J-PARC Center; 4Institute for Integrated Radiation and Nuclear Science, Kyoto University; 5Department of Communications
and Computer Engineering, Kyoto University

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MLF Annual Report 2021

Li Diffusion Studied by QENS with Single Crystal
1. Introduction
All-solid-state batteries using solid electrolytes
have significant advantages in terms of the energy density and safety [1]. Sulfide-based Li conductors, such as
LPGS, exhibit very high ionic conductivities 10–2 S/cm atroom temperature [2]. Although the oxide-based one
shows more than one order of magnitude lower conductivity, a better oxide-based Li conductor is highly demanded because of its stability in the air. La2/3-xLi3xTiO3(LLTO) has been widely studied because it has the highest Li ion conductivity (about 1 [mScm-1] at room temperature) among oxide solid electrolytes [3]. In addition,
LLTO has simple double-perovskite structure (Fig. 1b),which makes LLTO an ideal system for investigating themechanism of Li ion conduction.
Quasielastic neutron scattering (QENS) provides
detailed information on the dynamical conduction
path of Li+ on a microscopic scale. So far, the number of
QENS studies on solid-state Li conductors was limited
because detecting Li diffusion by QENS was a challenge
due to their weak signal. Furthermore, if a single crystal
is available, precise directional information of Li+ jump
can be obtained. Here, we show the first example of
QENS study using a single crystal of Li conductors [4].
Combined with first principle MD simulation, we could
obtain microscopic information on Li+ diffusion in LLTO.
2. Experimental details
To avoid strong neutron absorption of 6Li, 7Lienriched LLTO powder was synthesized from 7Lienriched Li2CO3, La2O3, and TiO2. The single crystals of
LLTO (x = 0.13) were grown at Shinshu University using a directional solidification method [5]. Although
there were some grains in the as-grown single crystal, we sliced the sample into 1.5-mm-thick slices andtook X-ray Laue diffraction with 5 mm intervals to
select single grain portions. Finally, a single-grain single-crystal with total volume of ~1 cm3 was obtainedby pasting back using special glue CYTOP which istransparent to neutrons. QENS data were measured
using backscattering spectrometer DNA at J-PARC [6].
DNA can offer various resolution and energy range byusing pulse-shaping chopper. In this study, we usedhigh-resolution mode (ΔE = 2.5 μeV, –20 < E < 80 meV)with 3 cm slit and chopper frequency of 300 Hz. Scan
trajectory of DNA in the horizontal scattering plane
forms arc around origin. By aligning the arc with thethree main crystal axes, [110], [001], and [111], we can
54measure QENS approximately along these directions up
to 1 Å–1 (Fig. 1a). In the Chudley-Elliot model, Lorentzian
linewidth Γ is zero when Q is perpendicular to jump
vector l. Thus, we can obtain directional information of
Li dynamics from these measurements.

Figure 1.	(a) Scan trajectories of [110], [001], and [111] measurements. (b) Crystal structures of LLTO [4].

3. Results
Figure 2a shows Q-dependence of Lorenzian
linewidth Γ obtained from fits of T = 600 K data withthe sum of a Lorentzian and a delta function convoluted with the resolution function estimated from theT = 150 K data. To analyze Γ (Q), we performed first principle MD simulations (Fig. 2b). Figure 2b shows trajectory of Li ions by yellow lines. Here we assume no La in
La-poor layer. Li ions are moving around the A site, andsome Li ions jump to the neighboring site. This is consistent with Reverse Monte Carlo results [7, 8]. Therefore,
we assumed a jump in the direction of [100], [010], andthe Q-dependence are well reproduced with jump vector between a-sites (dotted lines in Fig. 2a).

MLF Annual Report 2021

Research and Development Highlights

measurements.
It is interesting to compare the results with that of thesulfide-based Li ionic conductor Li7P3S11 measured withthe same instrument [9]. Although the measured temperatures are different, QENS with almost the same line
width were observed at T = 473 K for Li7P3S11. For LLTO, D at
T = 473 K is estimated from D at 600 K and Ea = 0.15 eV as
3.1 ± 0.3 × 10−6 cm2/s, which is close to D = 5.7 × 10−6 cm2/s
at T = 473 K for Li7P3S11. This indicates that same level of fastdiffusion is realized in sulfide and oxide-based Li conductor
in microscopic scale.
4. Summary
We precisely determined the dynamical conduction
path of Li+ ions in solid state electrolyte LLTO from anisotropic QENS using 7Li enriched single crystal and firstprinciples MD simulations. The self-diffusion coefficientsof Li+ ions in LLTO were found to be comparable withthose in sulfide-based Li+ ions conductor Li7P3S11 eventhough they had 10 times smaller ionic conductivity
than Li7P3S11. This microscopic information on Li+ diffusion can provide a way to increase Li+ ionic conductivity
in oxide-based solid electrolytes.
Figure 2.	(a) Q-dependences of Lorentzian linewidth G along
three principal axes [110], [111], and [001] measured
at T = 600 K. (b) Trajectories of Li+ ions in the ab-planeof La-poor layer simulated by MD using first-principles
modeling for LLTO [4].

From the obtained jump distance and residencetime, we estimated the diffusion coefficient D as
6.8 ± 0.5 × 10−6 cm2/s at T = 600 K and 1.9 ± 0.1 × 10−6 cm2/s
at T = 410 K. The ratio of the diffusion constant between
600 K and 410 K is 3.6, which agrees with the activationenergy of 0.15 eV obtained from the bulk ionic conductivity of LLTO above 400 K [3]. Thus, QENS captures thesame Li dynamics as the macroscopic ionic conductivity

References[1] M. Armand and J.-M. Tarascon, Nature (London) 451,
652 (2008).
[2] N. Kamaya, et al., Nat. Mater. 10, 682 (2011).
[3] Y. Inaguma et al., Solid State Commun. 86 (1993)
689.
[4] M. Matsuura et al., Phys. Rev. B 104 (2021) 094305.
[5] Y. Fujiwara et al., J. Cryst. Growth 433, 48 (2016).
[6] K. Shibata et al., JPS Conf. Proc. 8, 036022 (2015).
[7] K. Ohara et al., J. Phys. Condens. Matter 22, 404203(2010).
[8] K. Mori et al., Solid State Ion. 268, 76 (2014).
[9] K. Mori et al., Phys. Rev. Appl. 4, 054008 (2015).

M. Matsuura1, Y. Fujiwara2, H. Moriwake3, K. Ohara4, and Y. Kawakita5
Neutron Science and Technology Center, CROSS; 2Faculty of Engineering, Shinshu University; 3Nanostructures Research Laboratory, Japan
Fine Ceramics Center; 4Research and Utilization Division, SPring-8/JASRI; 5Neutron Science Section, Materials and Life Science Division,
J-PARC Center

1

55

Research and Development Highlights

MLF Annual Report 2021

Visualization of Generated Water in Newly-designed
Polymer Electrolyte Fuel Cell during Power Generation
1. Introduction
For increasing power density and durability, while
reducing the costs of polymer electrolyte fuel cells(PEFCs), the importance of water management in PEFC
is well known. Not only new materials and operational
protocols but also the cell structures directly affect thewater management.
The structure of the gas diffusion layers (GDLs) has
been extensively studied for better water and gas management [1‒3]. When the water produced at the cathode during power generation remains in the GDL or in
the gas flow channels (GFC), the liquid water inhibits the
diffusion of oxygen from the air to the catalyst layer (CL).
On the other hand, the liquid water enhances the power
generation when properly distributed.
Yamanashi University and ENOMOTO have developed an innovative GDL, “GDLFC+”, with gas flow channels fabricated on a flat separator that has enabled bothcost reduction and high performance [4]. The water distribution in a PEFC with GDLFC+ during the power generation was visualized by neutron radiography to further
improve the cell performance [5].
2. Experimental
Figure 1 shows the illustration of a PEFC used in theexperiment and Fig. 2 shows the structure of the GFC.

The separator was made of gold-plated aluminum. On
the cathode side, we adopted a newly designed GDLFC+
with 0.4 mm thick with a 0.04 mm thick microporous
layer as a GDL. On the anode side, a single serpentine
GFC was formed on the separator in a direction perpendicular to the cathode GFC (Fig. 2, middle panel), and acommercial GDL (22BB, SGL Co.) was used. The active

Figure 1.	Schematic illustration of the cell assembly for visualization of water distribution by neutron radiography during operation. 1: Cathode side GDLFC+. 2:
Anode side GDL (SGL Co., 22BB). 3: Cathode side Al
flat separator. 4: Anode side Al separator with GFC.
5: Catalyst Coated Membrane (CCM). 6: Gasket.

Figure 2.	Structures of GFCs applied to a single cell for visualization of liquid water during power generation, andthe locations of the GFCs both at the cathode and anode.

56

MLF Annual Report 2021

area of the cell was 1.0 cm × 9.7 cm [5].
In beamline BL22 of J-PARC MLF, the generated water in the cell was continuously monitored for 30 minutes with a pulsed neutron beam of 25 Hz repetition
rate during the power generation (Fig. 3) [6]. During thepower generation, humidified hydrogen and humidified
air/oxygen were supplied to the cell. The current density
was set between 1.0 and 3.0 A cm‒2.

Research and Development Highlights

We, then, changed the gas flow velocity in the GFC
from 1.35 to 2.34 m/s to find out that the gas flow velocity was a key factor for removing liquid water from the
GDL. With a water-repellent GDL, the water generated at
the cathode back-diffused efficiently through the electrolyte to the anode side. In addition, the heat generated by the cathode overvoltage also contributed to the
suppression of dew condensation on both the cathodeand anode.

3. Results
Figure 4(A) is an image of water distribution in the
PEFC perpendicular to the MEA during power generation using oxygen humidified at 73%RH at the current
density of 3.0 A cm‒2. Under this condition, the amountsof water observed in the outflow gas channel (OF) region, the inflow gas channel (IF) region and the porous
rib between the OF and IF changed from the upstream
to downstream. Figure 4(B) shows the water distribution in the gas upstream area (B-B cross section), where
the thickness of water in the OF region was apparently
larger than that in the IF region. Notably, in Fig. 4(C)showing the water distribution in the gas downstream
area (C-C cross section), the water thickness inside theribs increased more than that observed both in the OF
and IF regions. The accumulation of water was not the
only obstacle to gas diffusion via the ribs but should be
carefully controlled.

Figure 3. Photograph of the PEFC for water visualization.

Figure 4.	(A): Water distribution. Cell temperature = 75°C,
RH = 73%, current density = 3.0 A cm‒2, oxidant =oxygen. LW-IF: Water observed in the incoming gas
channel (IF). LW-OF: Water observed in the outflow
gas channel (OF). UPZ: Uniformed pressure zone.
(B): (B-B) Line profile of water thickness across the
GFC upstream of the gas. (C): (C-C) Line profile ofwater thickness downstream of the gas.

57

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MLF Annual Report 2021

4. Summary
We have succeeded in visualizing liquid water in an
operating PEFC using a newly-developed GDL, GDLFC+.
The relationship between the distribution of water andthe cell performance was clearly understood. With theresults obtained, we are designing new cells with higher
power output.
Acknowledgments
This research was partially promoted by the Ministryof Education, Culture, Sports, Science and Technology(MEXT) and the New Energy and Industrial Technology
Development Organization (NEDO).

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[2] Z. Wang, L. Qu, Y. Zeng, X. Guo, Z. Shao, B. Yia, RSC
Adv. 8, 1503 (2018).
[3] Z. Bao, Z. Niu, K. Jiao, J. Power Sources, 438, 226995(2019).
[4] M. Watanabe, H. Yanai, M. Nasu, J. Electrochem.
Soc., 166, F3210 (2019).
[5] M. Nasu, H. Yanai, N. Hirayama, H. Adachi, Y.
Kakizawa, Y. Shirase, H. Nishiyama, T. Kawamoto, J.
Inukai, T. Shinohara, H. Hayashida, M. Watanabe, J.
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[6] T. Shinohara, T. Kai, K. Oikawa, T. Nakatani, M.
Segawa, K. Hiroi, Y. Su, M. Ooi, M. Harada, H. Iikura,
H. Hayashida, J.D. Parker, Y. Matsumoto, H. Sato, Y.
Kiyanagi, Rev. Sci. Instrum., 91, 043302 (2020).

Mitsunori Nasu1, Hiroshi Yanai1, Naoki Hirayama1, Hironori Adachi1, Yu Kakizawa2, Yuto Shirase2, Hiromichi Nishiyama2,
Teppei Kawamoto2, Junji Inukai2, Takenao Shinohara3, Hirotoshi Hayashida4, and Masahiro Watanabe2
1
ENOMOTO Co., Ltd.; 2University of Yamanashi; 3Materials and Life Science Division, J-PARC Center; 4Neutron Science and Technology
Center, CROSS58

MLF Annual Report 2021

Research and Development Highlights

Molecular Motion Improves Solar Cell Performance:a Muon Spin Relaxation Study
1. Introduction
One of the most promising materials for next-generation solar cells that combine high efficiency and lower
cost is hybrid organic-inorganic perovskites (HOIPs).
Over 25% efficiency has been achieved using HOIPbased solar cells, which is on level with silicon-basedsolar cells. The cost of manufacturing HOIP solar cells
is dramatically lower than that of producing solar cells
using the existing commercial technique.
The microscopic principles underlying the high solar cell efficiency of HOIP are still not fully understood,
despite the advances that have been made. The long
carrier lifetime (≥1 μs) of HOIP is thought to be the key
factor in its outstanding photovoltaic conversion performance. Despite this material having a relatively low
charge mobility, it has a long carrier lifetime, which extends the carrier diffusion length [1]. Additionally, it has
been noted that solar cells can still function when the
hybrid structure of the solar cell is replaced with pure
inorganic perovskite. This indicates that inorganic metal
halide atoms are excited by photons to produce electrons and holes, which is in line with density functional
calculations that show that neither organic nor inorganic cations included inside the metal halide frames
directly contribute to the band-edge states. However,. The residual value ofν νL 0.2 µs− 1 at higher
temperatures is attributed to the diffusion of iodine ions in therelevant temperature range (19, 22).

the current efficiency of pure inorganic perovskites isonly 11%, which is significantly lower than the 25% seenin HOIP-based solar cells. This implies that the presenceof organic cations may be the key to reaching high solar cell efficiency, however at this point, it is unknown
exactly how organic cations increase efficiency on a microscopic level.
Muon provides information on a time scale of 10–910–5 s, which may be significant for carrier dynamics,
whereas quasi-elastic neutron scattering [2] and nuclear
magnetic/quadrupole resonance (NMR/NQR) using 1Hand 14N [3] probe molecular motion on a time scale of
10–12 s. In this regard, the failure of NMR experiments
using 207Pb and 127I due to fast spin-spin relaxation ratefurther supports the use of μSR to examine molecularmotion. Therefore, we conducted μSR studies on the
prototype methylamidinium (MA) lead iodide, in which
the implanted muons investigate the fluctuation of local
magnetic fields at interstitial points.
2. Results and discussion
As seen in Fig. 1a, the 3D network of corner-shared
PbI6-octahedra and MA molecule ions at the perovskite
A site form up the crystal structure of HOIP. It is known
that when temperature rises, MAPbI3 passes throughrelationship between the lifetime of photoexcited carriers and the
MA molecular motion, which can be understood by consideringthat the mechanism causing the change in∆ is also in effect for

A

C

B

D

b)

a)

The crystal structure of CH 3 NH3 PbI3 in the orthorhombic phase, where the organic cation (MA) is located in the center of a cage with PbI
6 octahedrons
at the corners. It is inferred from µ SR and DFT calculations that the implanted muons occupy the (0.48, 0.028, 0.27) site in the unit cell (Mu, marked by a redball). The color contour map shows the differential total formation energy for an interstitial hydrogen obtained by the DFT calculation.

new materials for a better solar cell performance. It is not easy, the orthorhombic-to-tetragonal structural transition at T

Figure 1.	a) Schematic diagram of the perovskite unit cell for CH3NH3PbI3. The organic cation is located in the center of a PbI6 octahedral cage. The color contour plot shows the differential total formation energy for aninterstitial hydrogen on the ac-plane obtained by the DFT calculation. b) Geometry of the MA moleculewith schematic drawing for the two modes of jumping rotation, where C3/C4 denotes the threefold/
fourfold rotation symmetry with τi–1 being the respective jumping frequencies. The calculated local
charge asymmetry is also shown superimposed as green and purple regions that produce an electric
dipole moment P, which results in the effective electric dipole moment P̄ due to the C3/C4 motion.

59

Research and Development Highlights

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two structural transitions: first, from an orthorhombic
to a tetragonal structure at TOT = 165 K, then from a tetragonal to a cubic structure at TTC = 327 K. The resultant
μSR time spectra are well represented by the quasi-static
Kubo-Toyabe relaxation function, which is characterized
by the nuclear dipolar width Δ and the fluctuation rate ν,
as shown in Fig. 2. Simultaneous curve-fits of the spectra
at different longitudinal fields successfully determined
the parameters. Figure 3 displays the temperature dependence of Δ and ν. In response to the change in theanisotropic motion of a cation molecule brought on bysuch structural phase transitions, it turns out that themagnitude of Δ exhibits a strong temperature dependence. The molecular motion of MA is restricted around
its three-fold rotational symmetry (C3) in the orthorhombic phase, according to earlier studies using neutron
scattering and NMR/NQR [2, 3], whereas four-fold rotational symmetry (C4) is observed in addition to C3 in thetetragonal and cubic phases at higher temperatures.
Considering that the time scale for these rotational
jumps is 10–11-10–12 s for the relevant temperature range(>10 K) [2, 3], it is reasonable to assume that the averaging out of the nuclear dipolar fields, or the so-called

motional narrowing effect, is what causes the reductionof Δ above 120 K.
On the other hand, the fluctuation rate νdisplays adiverging increase synchronous with the reduction of
Δ above ~120 K, which is then dramatically reduced approaching 165 K. When reaching 200 K, it shows a sharp
increase before plateauing at a constant value (~0.2 μs–1).
Even while there appears to be some link between thefeature of Δ at 120–165 K and that of ν, we should pointout that the slower variation of Δ, as represented by theparameter ν, cannot be directly attributed to the MA
molecular motion, which is orders of magnitude fasterthan that estimated from ν.
More intriguingly, at about T = 165 K, a small humpof Δ is observed. In Fig. 3c, it is noticeable that the entire
temperature dependence of Δ is strikingly analogous tothat observed in the temperature dependence of photoluminescence (PL) lifetime τPL [4, 5]. This strongly implies a connection between the MA molecular motion
and the long lifetime of the photoexcited carriers. It is
assumed that the dielectric response, which prevents
carrier recombination, is significant for the lifetime ofthe photoexcited carriers. The MA molecule moves to

Figure 2.	a) Typical examples of ZF-µSR time spectra (asymmetry) observedin MAPbI3 at various temperatures, and b) the corresponding contour plot for asymmetry versus temperature.

60

MLF Annual Report 2021

Research and Development Highlights

inductively protect the photoexcited carriers when its
width. It is suggested that the effective electric dipole
rotating motion is moderate, enhancing the carrier lifemoment of the MA molecules, which is related to the
local dielectric susceptibility, strongly influences the cartime. In other words, our findings imply that one of theprerequisites for the MA molecule to demonstrate an efrier lifetime.
parameter is proportional to ∆ M / νM . Thus, the behavior in ν
the ﬂuctuation of ∆ L . Note that this m
fective dielectric response is local freedomofmotiononseen for Θ3 ≤ T ≤ T OT in Fig. 3B can be interpreted as that averaging of∆ around the C3 axis.
to the increase in the References
jump rotation frequency of the MA
It is remarkable that the overall tem
a time scale comparable to the carrierdue
lifetime.
molecule around theC3 axis.
∆ , including the hump around T OT , isM. K
Brenner
et al., Nat.toRev.
1 (2016) 15007.
The change inν for Θ4 ≤ [1]T ≤T.220is also attributed
the Mater.
that observed
for the photoluminesce
similar mechanism acting on∆
to thejumpingChem.
shown
in Fig.
4A, the longer lifetime
3. Summary[2] T T.due
Chen
etincreaseal., Phys.ofChem.
Phys.
17 (2015)
rate around the C4 axis, where∆ M and ∆ T in Eq. 5 are replaced decrease aboveΘ3 , which is followed
In conclusion, the local field fluctuation
on31278-31286.
by ∆ M brought(the remaining
contribution
from the MA molecules)
T OT and the further reduction abov2
observed
for theshorter lifetime (τ PL2 )( ∆ 2T − ∆ 2M ) 1/ [3], consisting
only of the
PbI3 J.latticeby ∆ Lto[=detectby nuclear magnetic moments allowsandmuons
G. M. Bernard
et al.,
Phys. Chem.
A 122(2018)
contribution] with their ﬂuctuation rate νM and νL , respectively. in Fig. 4B that these behaviors arechanges in the MA molecular motion.
ThevariationThe
increaseof νinfor T OT ≤ T ≤1560.
200 K is then understood as reduction of τ 3 and subsequent onseof νM , and the turnover
above
~ 200
K PNASis describedby increasing
the carrier lifetime determined by thethat
PL measurement
Chenet al.,
114 (2017)7519-7524.temperature. Such correla[4]T.
ν ∝∆ 2M / νM . The residual value ofν νL 0.2 µs− 1 at higher relationship between the lifetime of pho
is commensurate with the variation temperaturesin nuclear dipole
Lee, private[5]theS.H.
communication.
is attributed todiffusionof iodineions in the MA molecular motion, which can be u
relevant temperature range (19, 22).

0.25

Δ (μs-1)

A

1
H
2

0.20

D

(a)

0.15

C
(c)

0.10
0.05

Ortho

0.00

Tetra

Cubic

0.50

B

(b)

0.40
ν (μs-1)

that the mechanism causing the chan

(d)

D

0.30
0.20
0.10
0

100
200
300
Temperature (K)400

Downloaded at Diane Sullenberger on January 20, 2022

0.00

Figure 3.	Temperature dependence of a) the dipolar width, b) the fluctuation rate, c) the photoluminescence (PL)
lifetime quoted from Ref. [4] and d) the relaxation time τ3(τ4) of the rotational motion around the C3(C4)axis determined by quasi-elastic neutron scattering (after Ref. [2]). Circle (triangle) symbols in panels a)
and b) represent data on sample consisting of CH3NH3+ (CD3NH3+), respectively. The dashed curve inpanel c) indicates the T-dependence of Δ(1H).

A. Koda1,2, H. Okabe1,2, M. Hiraishi1,2, R. Kadono1,2, K. A. Dagnall3, J. J. Choi3, and S. H. Lee3
Muon Science Section, Materials and Life Science Division, J-PARC Center; 2Institute of Materials Structure Science, KEK; 3Department of
Physics, University of Virginia

161Research and Development Highlights

MLF Annual Report 2021

High Resolution Spectroscopy of Electronic K X Rays
from Muonic Atoms
1. Introduction
When a negative muon is captured by an atom,
normally in a highly excited level (nμ > 20, where nμ
represents a muon principal quantum number), themuon starts to cascade towards the nucleus first by
muon-induced Auger decay and then via radiative decay emitting muonic x rays. The former process dominates at the beginning of the cascade, accompanying
electron ejection from M shell, followed by L and K shell.
The latter radiative decay is important when the muon
approaches the lower levels. When an electronic holeis formed during this cascade process, it is filled by theupper-level electrons via emission of electronic characteristic x rays or electronic Auger decay. In addition, inside a solid-state target, electron side feeding also takes
place, where an electron transfers from the surrounding
atoms to the muonic atom [1]. Finally, the muon reaches
the atomic 1s ground state. The timescale of the cascade
process is typically ~10 fs for an Fe atom.
Dynamical aspect of the muon cascade has beenstudied by examining the intensity distribution of themuonic x-ray line series. The energies of the muonic xrays also encode information on the bound electrons,
because the screening of the nuclear charge by theseelectrons modifies their energies [2]. An alternative
approach is provided by observation of the electronic
characteristic x ray from muonic atoms [3]. The electronic K x ray is a sensitive probe for the electron dynamics
because the electron-electron interaction contributes
more significantly to the energy of the K x rays than themuonic x rays. However, the insufficient resolution of
conventional x-ray detectors has prevented further detailed study.
In this study, we report high-resolution measurements of electronic K x rays emitted from a muonic Fe(μFe) using state-of-the-art superconducting transition-edge sensor (TES) microcalorimeters [4]. The TES
detector utilizes the steep temperature dependence ofresistance at the superconducting phase transition [5]and realizes both a high energy resolution and a highdetection efficiency.
2. Experiment
The measurement was carried out at the D2 beamline of the Materials and Life Science Experimental
Facility (MLF) at J-PARC. Details of the experimental
62

setup can be found elsewhere [4]. Briefly, the pulsed
negative muon beam with low momentum (20.5 MeV/c)
was irradiated to a 100 μm-thick Fe foil target tilted by
45° with respect to the muon-beam direction. X rays
emitted from the target were measured by the TES xray detector placed normally to the muon-beam direction. The x-ray energy and detection time with respect
to the pulsed muon beam injection were simultaneously
accumulated.
The x-ray detector is based on a 240-pixel TES array developed by the National Institute of Standards
and Technology (NIST) [5]. Each pixel contains a TES
consisting of a bilayer of thin Mo/Cu films whose superconducting critical temperature is about 107 mK, and a
4 μm-thick Bi absorber for converting x-ray energy into
heat. The effective area of each pixel is 305 × 290 μm2
and the total active area of the array is about 23 mm2.
The TES array was cooled with a pulse-tube-backed adiabatic demagnetization refrigerator (ADR). The TES bathtemperature was regulated to 70 mK ± 5 μK rms. Energy
calibration of the TES detector was performed by using
an x-ray generator installed at the front of the detector.
The characteristic x rays from Cr, Co, and Cu were used
as calibration x-ray lines. The accuracy of the energy calibration was better than 0.6 eV.
3. Results and discussion
The x-ray spectrum shown in Fig. 1(a)was obtained
after applying a time window to extract the beam-correlated signals. The energy resolution was evaluatedto be 5.2 eV (FWHM). We observed an asymmetric andbroad structure starting from the Mn Kα1 and Kα2 energies (5899 and 5888 eV) and extending across 200 eV.
This peak was assigned to electronic Kα x rays from μFe.
A similar structure for electronic Kβ x rays from μFe was
identified, which starts from the energy of Mn Kβ x-ray
line at 6490 eV. We also found a broad tail-like structure
beneath the peak of muonic x rays from μBe at 6179 eV,
which was determined to be the hypersatellite Khα xrays from μFe, the characteristic x rays from double
K-shell hole states [6].
The energies of the electronic K x rays emitted fromμFe during the cascade process were affected both by
the muon state and by the electron configuration at the
moment of the x-ray emission. To evaluate these energy
shifts, we calculated the energies of the electronic K x

MLF Annual Report 2021

Research and Development Highlights

Figure 1.	(a) The x-ray spectrum in the energy range from 5600 to 6850 eV measured by
the TES detector [4]. The Fe Kα peak is emitted due to direct ionization of thetarget by the incident beam. We also observed a sharp peak of muonic x-rays
from μBe around 6200 eV, which is emitted from a Be x-ray window at the frontof the TES detector. (b) Calculated Kα and Kβ x-ray energies from μFe under different muon states nμ and electron configurations with L holes NLhole.

rays from μFe by employing a non-relativistic density
functional theory [7]. The calculated μFe Kα and Kβ x-ray
energies are shown in Figs. 1(b) for various muon statesand electron configurations, which are represented by
the muon principal quantum number nμ and the number of the L-shell electron holes NLhole, respectively. The
K x-ray energies decrease at the lower muon levels n μ
because the muon screens the nuclear charge and thisscreening effect gets stronger at the lower nμ. Whennμ =1, the K x-ray energy almost corresponds to thatfrom the Z - 1 atom, i.e., Mn K x rays. On the other hand,the shift due to different electron configurations strongly depends on NLhole and we found a systematic shift tohigher energy for large NLhole. The observed broadening can be explained by the convolution of these two
effects.
The net peak shapes of the μFe K x rays reflect thetemporal evolution of the muon state and electron
configuration during the muon cascade. We performeda simulation of the cascade, which involved not only
muon-induced but also electron-induced processes.
Particularly, we took into account the M-shell side-feeding process, the electron transfer from the surrounding
Fe to the M shell of the μFe.
Figure 2(a) shows the results of the simulation forKα x rays. The experimental Kα spectrum was fitted withthe simulation curve, where the M-shell per-hole sidefeeding rate ΓM was treated as a fitting parameter. It isclearly seen that the M-shell side-feeding rate changes
the whole spectrum drastically, and a simulation neglecting side feeding (ΓM = 0.0 fs−1) does not explain theobserved feature at all. The best result was obtainedat the side-feeding rate of ΓM = 0.35 (2) fs−1. Using thesame values of ΓM, we also reproduced the hypersatellite Khα x-ray and Kβ x-ray spectra as shown in Figs. 2(b)and 2(c), respectively. The excellent agreement of thepresent simulation with the spectrum obtained experimentally strongly supports our interpretation of the involved dynamics.
4. Summary
We showed that the high-resolution spectroscopyof electronic K x rays from muonic atoms could be used
as a good probe for studying the temporal evolution ofelectron dynamics during the muon cascade process,which has remained unresolved for decades. In addition, we found that the K X-ray spectrum is very sensitive
to the side-feeding effect from the surroundings. Thismethod suggests a new way to revisit the dynamics ofmuonic atoms not only in metals but also in semiconductors, insulators, and molecules.
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Figure 2.	Comparison of the simulated and corresponding measured K x-ray
spectra [4]. The simulated spectra are after convolution by the energy response function of the TES detector. (a) Simulated Kα x-ray
spectrum with three side-feeding rates. (b), (c) Simulated hyper satellite Khα and Kβ x-ray spectra under the same parameters as (a) withΓM = 0.35 fs−1.

References[1] F. J. Hartmann, in Muonic Atoms and Molecules,
edited by L. A. Schaller and C. Petitjean (Birkhäuser
Verlag Basel, Basel, 1993), pp. 157–165.
[2] L. Simons et al., Nucl. Instr. and Meth. B, 87 293(1994).
[3] H. Schneuwly and P. Vogel, Phys. Rev. A, 22 2081

(1980).
[4] T. Okumura et al., Phys. Rev. Lett., 127 053001 (2021).
[5] J. N. Ullom and D. A. Bennett, Supercond. Sci.
Technol. 28 084003 (2015).
[6] R. Diamant et al., Phys. Rev. A 79 062511 (2009).
[7] X. M. Tong and S. I. Chu, Phys. Rev. A 55 3406 (1997).

T. Okumura1,2, T. Azuma2, D.A. Bennett3, P. Caradonna4, I. Chiu5, W.B. Doriese3, M.S. Durkin3, J.W. Fowler3, J.D. Gard3, T. Hashimoto6,
R. Hayakawa7, G.C. Hilton3, Y. Ichinohe7, P. Indelicato8, T. Isobe9, S. Kanda10,11, D. Kato12, M. Katsuragawa4, N. Kawamura10,11, Y. Kino13,
M.K. Kubo14, K. Mine4, Y. Miyake10,11, K.M. Morgan3, K. Ninomiya5, H. Noda15, G.C. O’Neil3, S. Okada16,2, K. Okutsu13, T. Osawa17,
N. Paul8, C.D. Reinstema3, D.R. Schmidt3, K. Shimomura10,11, P. Strasser10,11, H. Suda18, D.S. Swetz3, T. Takahashi4, S. Takeda4,
S. Takeshita10,11, M. Tampo10,11, H. Tatsuno18, X.M. Tong19, Y. Ueno2, J.N. Ullom3, S. Watanabe20, and S. Yamada7
1
Department of Chemistry, Tokyo Metropolitan University; 2Atomic, Molecular, and Optical Physics Laboratory, RIKEN; 3National Instituteof Standard Technology; 4Kavli IPMU, The University of Tokyo; 5Department of Chemistry, Osaka University; 6Advanced Science ResearchCenter, JAEA; 7Department of Physics, Rikkyo University; 8Laboratoire Kastler Brossel, Sorbonne Université, CNRS, ENS-PSL Research
University; 9RIKEN Nishina Center, RIKEN; 10Technology Development Section, Materials and Life Sci-ence Division, J-PARC Center;
11
Institute of Materials Structure Science, KEK; 12National Institute of Fusion Science; 13Department of Chemistry, Tohoku University;
14
Department of Natural Science, College of Liberal Arts, International Christian University; 15Department of Earth and Space Science,
Osaka University; 16Engineering Science Laboratory, Chubu University; 17Materials Sci-ences Research Center, JAEA; 18Department of
Physics, Tokyo Metropolitan University; 19Center for Computational Sciences, Uni-versity of Tsukuba; 20Department of Space Astronomy andAstrophysics, JAXA

64

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Research and Development Highlights

Rabi-Oscillation Spectroscopy for Precise Measurementof Hyperfine Structure of Muonium Atom
The muonium (Mu), in which a positive muon andan electron are bound together, is known as one of theexotic atoms. The spectroscopy of Mu atoms is a potential tool for discovering novel physics in particle physics research. The positive muon and the electron are
point-like lepton particles in the Standard Model (SM) of
particle physics, hence their contribution to the strong
interaction is minor and well known when compared tohydrogen. The Mu hyperfine structure (HFS) can be used
to calculate the muon-to-electron mass ratio. Since theelectron mass has been carefully determined, muonium
HFS spectroscopy offers the most precise estimate of
the muon mass, which is an important input parameterfor determining SM parameters like the Fermi coupling
constant [1, 2]. Also, the precise measurement of themuonium HFS is important in order to determine themuon anomalous magnetic moment, g−2 [3–5].
We developed a novel method of atomic spectroscopy, which we named Rabi-oscillation spectroscopy.
In this method, the resonance frequency is obtained
from the time response to only one frequency. Timeintegrated data were utilized in standard spectroscopy
to analyze the behavior of atoms when the frequency
was changed. We came up with a new notion – or, to
put it another way, an inverse way of thinking – and developed a new approach for measuring the resonancefrequency by solving an inverse problem. The answer isfound by comparing the resonance signal to a theoretical simulation of Rabi oscillations without transforming
the signal from the time domain resonance signals tofrequency domain resonance signals.
In the atomic world, allowed states appear as discrete energy quantum levels, with the frequency ofthe electromagnetic wave produced or absorbed during a transition between levels severely determined by
the energy difference between those levels. We will beable to precisely test the rules of physics in microscopic
events if we can properly determine this resonancefrequency. An atom or molecule is stimulated by electromagnetic radiation, such as lasers or microwaves inconventional spectroscopy, and the resonance center isthe position where the signal is the highest.
In practice, the resonance frequency is determinedby changing the frequency of the electromagnetic
wave. The symmetrical resonance curve obtained bydrawing each signal strength on a graph is used todetermine the resonance frequency at which the curve
reaches its maximum peak. Controlling the experimental conditions, such as the consistent power of the electromagnetic wave, is necessary for exact measurements.
Furthermore, data at frequencies with low signal intensity, which correspond to the foothills on the curve, arerequired in order to obtain correct resonance curves. As
a result, this approach is not always effective for exact
measurements.
We paid attention to the Rabi oscillations, which
are induced by atoms interacting with electromagnetic
waves and cause the signal intensity of the transition tooscillate over time. The signal oscillations are large andslow if the electromagnetic wave frequency matches oris close to the resonance frequency, but small and quick
if the difference between the two frequencies, or the detuning, is considerable. The power of electromagnetic
waves is another determining factor. When the poweris high, the signal grows large and quick, and when the
power is low, the signal becomes small and slow. These
combinations are distinct from the case in which the detuning is changed as shown in Fig. 1.
Using this feature, the detuning and power can be
determined simultaneously from the combination of
signal strength and oscillation speed. In other words,
since the detuning is known, the resonance frequency
can be obtained by subtracting it from the known frequency of the electromagnetic wave, regardless of thepower.
After confirming the validity of the principle
through theoretical simulations, we conducted experiments to measure Mu HFS with actual Mu atoms
at J-PARC MLF, and analyzed the experimental data using the Rabi-oscillation method. The obtained result isshown in Fig. 2 and is nearly twice as precise as the previous experiment [6]. In the future, further experiments
will be conducted aiming at 100 times higher precision.
In spectroscopy of atoms, containing short lived
subatomic particles and nuclei produced using accelerator facilities, it is necessary to make brief observations
with as much power as possible to obtain the maximum
signal from a limited observation time and a small number of atoms. Since it can measure resonance frequencies with high precision and efficiency, Rabi-oscillation
spectroscopy is a novel and powerful technique applicable to the measurement of atomic resonances.
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Figure 1.	Standard spectroscopy on the left-hand side and Rabi-oscillation spectroscopy on theright-hand side.

Figure 2. Results obtained by Rabi-oscillation spectroscopy.

References[1] K. S. Tanaka et al., Prog. Theor. Exp. Phys. 2021,
053C01 (2021).
[2] S. Kanda et al., Phys. Lett. B 815, 136154 (2021).
[3] M. Abe et al., Prog. Theor. Exp. Phys. 2019, 053C02(2019).

[4] A. Keshavarzi, D. Nomura, T. Teubner. Phys. Rev.
D 101 014029, (2020).
[5] B. Abi et al. Phys. Rev. Lett. 126, 141801 (2021).
[6] S. Nishimura et al. Phys. Rev. A 104, L020801 (2021).

S. Nishimura1,2 (MuSEUM Collaboration)
1
Muon Science Section, Materials and Life Science Division, J-PARC Center; 2Institute of Materials Structure Science, KEK

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Research and Development Highlights

Measurements of the Neutron Capture Cross Section of243
Am around 23.5 keV
1. Introduction
Accurate nuclear data for minor actinides (MAs) inhigh level nuclear waste (HLW) have been importantsince they are necessary for developing the design andperformance of transmutation systems to reduce theinventory of HLW [1]. A promising option among the
proposed nuclear transmutation systems is the acceleratordriven system (ADS), a subcritical reactor that compromise
an accelerator-driven neutron source together with a fuelcontaining MAs. The contribution of uncertainties ofthe evaluated nuclear data JENDL-4.0 to reactor physics
parameters was quantified in a recent work [2]. It has
been shown that the 243Am neutron capture cross section is one of the main contributors among all MAs. In
the neutron energy of interest, from 0.5 to 500 keV, theuncertainties for the capture cross section of 243Am in
JENDL-4.0 have been evaluated to be 10% or higher, thatstem from the poor quality of the experimental data.
There are only two data sets for the neutron capture
cross section of 243Am in the fast neutron energy region
using the time-of-flight (TOF) method [3, 4]. Both results
have discrepancies, although they agree with the large
uncertainties.
In the present work, the neutron capture cross section of 243Am was measured using the neutron filteringsystem in BL04 named the Accurate Neutron-Nucleus
Reaction measurement Instrument (ANNRI) at theMaterials and Life Science Experimental Facility (MLF)
in the Japan Proton Accelerator Research Complex(J-PARC).
2. Experiments
The present measurements were performed at BL04
with a highly intense pulsed neutron beam provided
by the spallation reaction of a mercury target. The incident neutron energy was determined by the neutron
TOF method. However, the reconstruction of the neutron TOF to neutron energy is complicated due to the
double-bunch mode, where two proton bunches with atime difference of 0.6 μs are shot to the spallation target
to generate the neutron beam. In the keV energy region,
the time difference is not negligible for the neutron TOF
measurements. Both proton pulses cause two neutron
production times, leading the energy ambiguities ofneutrons at the same TOF. To solve this serious issue, therecently implemented neutron beam filtering system

was employed in the present measurements [5]. A
20 cm Fe filter was used to make a quasi-monoenergetic
neutron beam with the averaged energy of 23.5 keV. In
addition, a Cd filter was used to cut off frame-overlap
neutrons, which are low-energy neutrons coming frompreceding neutron bursts. Capture gamma-rays emitted
from a sample were detected with a NaI(Tl) detector located at a distance of 27.9 m from the moderator of theneutron source. Anode signals from the NaI(Tl) detector are fed into a digital data acquisition system (CAEN
V1720) [6], recording the neutron TOF and pulse height(PH) of the signals.
A pellet of 38.14 mg of 243Am dioxide enclosed in an
Al container with Y2O3 binder was used in the present
measurements. A disk-shaped sample with a mass of
38.14 mg enclosed in an Al container was used for thepresent work. A dummy sample containing only Y2O3 in
Al case was measured to derive the background inducedby the Al case and a natC sample was used to estimate
the scattering neutron background by a sample. In thepresent analysis, the neutron capture cross section of243
Am was derived relative to the capture cross sectionof 197Au. Thus, a gold sample was used as standard inthis measurement. Additionally, a boron sample wasused to measure the incident neutron energy spectrum
by detecting 478 keV γ-rays from the 10B(n, αγ)7Li reaction. Finally, a “blank” measurement with no sample
was performed to estimate the sample-independent
background.
3. Analysis
The experimental data were analyzed in offline
analysis, which was stored in two-dimensional list datawith the neutron TOF and the PH. The TOF spectra for
243
Am, boron and the dummy sample measurements areshown in Fig. 1. A clear peak appears in the TOF region
from 12.6 μs to 15.0 μs, corresponding to 23.5 keV, at
the total cross section of Fe becomes minimum and thetransmission rate of neutrons is high. A TOF gate shownas the colored region in Fig. 1 was set for data analysis.
PH spectra in the TOF gate were extracted for 243Am,
dummy, carbon, blank and gold runs. In the PH analysis, the backgrounds related to sample-independent
components, dummy case and the scattered neutrons
were subtracted from the 243Am spectrum. After background subtractions, the neutron capture yield of 243Am
67

Research and Development Highlights

MLF Annual Report 2021

was derived by applying the pulse-height weighting
technique [6]. The data of the gold measurement wereanalyzed in the same manner and the capture yield of
197
Au was obtained. The neutron capture cross section of243
Am was determined at the neutron energy of 23.5 keV
relative to the 197Au neutron capture yield with the evaluated cross section data of 197Au.

lower than the latest value reported by Kimura et al. [9].
In accordance with the update of the nuclear data, bothdata were renormalized by the JENDL-4.0 capture crosssection of 197Am for the data from Ref. [3] and the thermal cross section of 243Am in Ref. [9] for the data from
Ref. [4]. The renormalized past experimental data arecompared with the present value in Fig. 2(b). Agreementwith the data of Weston et al. with the present value has
been improved, but the data of Wisshak et al. are still
lower than the present value.

Normalized Counts (/0.1µs)

4. Result
The neutron capture cross section of 243Am around23.5 keV was found to be 2.52 ± 0.14 b. The major components of the uncertainties were the statistical uncertainties (3.1% for 243Am and 2.5% for 197Au) and theuncertainty of the evaluated cross section of 197Au (3%).
The present result was compared to the past TOF experimental results of Wisshak et al. [3] and Weston et al. [4]together with the evaluated data from the JENDL-4.0 [7]and ENDF/B-VIII.0 [8] in Fig. 2. The cross section was determined with a smaller uncertainty than the past measurements. The data of Wisshak et al. are 20% lower thanthe present result and the data of Weston et al. is slightly
lower than the present result. For the evaluated data,
the JENDL-4.0 data are 7% smaller than the present value and ENDF/B-VIII.0 data are 5% larger but agree within
the experimental uncertainty.
Both past measurements used old evaluation data
for normalization: the capture cross section of 197Au in
ENDF/B-V 5% smaller than that of JENDL-4.0 by Weston
et al. and the thermal capture cross section of 243Am 15%

100

5. Conclusion
The neutron capture cross section of 243Am around23.5 keV was measured with the quasi-monoenergetic
neutron beam by the neutron filtering system in ANNRI(BL04). The cross section was determined with a smaller
uncertainty than the past measurements. It has beenshown that the disagreement between the present result and the data of Ref. [3, 4] has been improved after
renormalization of the past data to the latest value ofthe thermal capture cross section of 243Am. Further information about the present measurements can be foundin Ref. [10].
6. Acknowledgments
The present work is funded by the MEXT Innovative
Nuclear Research and Development Program of the
Ministry of Education, Culture, Sport, Science andTechnology. Grant Number: JPMXD0217942969.

Neutron Energy (keV)
50
30
20

10

Am-243
Dummy sample
Boron

10-1
10-2

23.5 keV

10-3
10-4
5

10

15
Time (µs)

20

Figure 1.	TOF spectra of the 243Am sample (red), the boron sample (black) and the dummy sample (blue) measured
with the NaI (Tl) detector.

68

Cross Section (b)MLF Annual Report 2021

(a)

3
2
This work
Weston+ (1985a)
Weston+ (1985b)
Wisshak+ (1983c)
Wisshak+ (1983d)
Wisshak+ (1983e)1010Wisshak+ (1983f)
Wisshak+ (1983g)
Wisshak+ (1983h)
JENDL-4.0 (2011)
ENDF/B-VIII.0 (2018)

15
20
25
Neutron Energy (keV)

4
Cross Section (b)Research and Development Highlights

30

(b)

3
2
This work✫Weston+ (1985a)✫Weston+ (1985b)✫Wisshak+ (1983c)✫Wisshak+ (1983d)✫Wisshak+ (1983e)1010✫Wisshak+ (1983f)✫Wisshak+ (1983g)✫Wisshak+ (1983h)
JENDL-4.0 (2011)
ENDF/B-VIII.0 (2018)✫ : renormalized

15
20
25
Neutron Energy (keV)

30

Figure 2.	(a) Capture cross section of 243Am. Comparison of thepresent result with past measurements and the evaluated data. (b) Comparison with the past data renormalized with the latest standard cross section.

References[1] M. Salvatore et al., “uncertainty And Target Accuracy
Assessment for Innovative Systems using Recent
Covariance Data Evaluations.” WPEC-26, OECD NEA,
(2008).
[2] H. Iwamoto et al., J Nucl. Sci. Technol., 50 8 (2013).
[3] K. Wisshak et al., Nucl. Sci. Eng. 85 3 (1983).
[4] L.W. Weston et al., Nucl. Sci. Eng. 91 4 (1985).

[5] G. Rovira et al., Nucl. Instrum. Methods. Phys Res.
1003 (2021).
[6] R. L. Macklin et al., Phys. Rev. 159 (1967).
[7] K. Shibata et al., J. Nucl. Sci. Technol., 48 1 (2011).
[8] D.A. Brown et al., Nucl Data Sheets. 149 (2018).
[9] A. Kimura et al., Nucl. Sci. Technol., 56 6 (2019).
[10] Y. Kodama et al., Nucl. Sci. Technol., 58 11 (2021).

Y. Kodama1, T. Katabuchi1, G. Rovira2, A. Kimura2, S. Nakamura2, S. Endo2, N. Iwamoto2, O. Iwamoto2, J. Hori3, Y. Shibahara3,
K. Terada3, H. Nakano1, and Y. Sato1
1
Laboratory for Zero Carbon Energy, Tokyo Institute of Technology; 2Nuclear Science and Engineering Directorate, Japan Atomic Energy
Agency; 3Institute for Integrated Radiation and Nuclear Science, Kyoto University

69

Research and Development Highlights

MLF Annual Report 2021

Wide Bandwidth Neutron-Spin Polarizer Due toFerromagnetic Interlayer Exchange Coupling
1. Introduction
A neutron polarizing supermirror is one of themost important optical devices to polarize a neutron
beam [1, 2]. It is a stack of alternating layers of ferromagnetic (FM) and non-magnetic materials with a variation in bilayer thickness to extend the bandwidth of theneutron polarization. We have developed an Fe/Ge polarizing supermirror by using the ion-beam sputtering
technique [3]. A wide bandwidth is important especiallyfor time-of-flight instruments installed at spallation neutron sources, such as the J-PARC MLF, since it determines
the available wavelength-range of polarized neutrons.
It is important to increase the ratio m of the critical momentum transfer of the supermirror to that of nickel toextend the bandwidth. The spontaneous magnetizationof the ion-beam sputtered Fe/Ge multilayer, however,disappears when the Fe layer thickness is reduced to
2-3 nm because the Curie temperature drops below theroom temperature. This limits the m-value of the polarizing supermirror because the multilayer fails to form ahigh and low contrast in the scattering length density
profile for spin-up and -down neutrons [4].
To overcome this problem, we propose a modification of the layer sequence, where the minimum Fe
thickness has been set to 3.5 nm, with the Ge thickness
reduced to keep the bilayer thickness at the reference

value of a standard supermirror. This invoked the FM
interlayer exchange coupling in the Fe/Ge multilayer
in a Ge thickness range from 1.2 to 2.2 nm. The performance test of the Fe/Ge neutron polarizing supermirror
showed a marked increase in the m-value, meaning thatthe modified layer sequence offered a solution to the
problem of the decrease of saturation magnetization
when the Fe thickness decreases in the original layer
sequence.
2.	Polarized neutron off-specular scattering
measurement
The polarized neutron off-specular scattering
measurement was performed on the polarized neutron reflectometer SHARAKU with a horizontal scattering geometry at the J-PARC MLF [5]. Figure 1 shows
the polarized neutron off-specular scattering images of
Fe/Ge periodic multilayers with 50 bilayers (sample (A)Fe: 3.5 nm, Ge: 2.2 nm, sample (B) Fe: 3.5 nm, Ge: 1.2 nm).
The scattering was spread over a wide qz range for (A).
This means that moments were not correlated in theout-of-plane direction. Contrary, the scattering was concentrated on the first Bragg condition (qz ≈ 1.34 nm−1)
for (B). The simulation based on the distorted wave Born
approximation demanded a model where areas with auniform orientation of moments between neighboring

Figure 1.	Measured and simulated polarized neutron off-specular scattering images of ion-beam sputtered
Fe/Ge periodic multilayers with 50 bilayers. Sample (A) Fe: 3.5 nm, Ge: 2.2 nm, Sample (B) Fe: 3.5 nm,
Ge: 1.2 nm. The FM interlayer exchange coupling when the Ge thickness is less than 2 nm resulted
in a scattering localized at the first Bragg condition (qz ≈1.34 nm–1).

70

MLF Annual Report 2021

Fe layers were ferromagnetically coupled. The measured and simulated result indicates that the FM interlayer exchange coupling in our Fe/Ge system grows
with decreasing Ge thickness when the Ge thickness is
reduced to less than 2 nm. The FM interlayer exchange
coupling observed here contributed to the presenceof saturation magnetization comparable to the bulk
and to smaller coercivity and larger initial permeability
than the multilayer without the FM interlayer exchange
coupling. This offers a possibility to keep the spontaneous magnetization for the multilayer with a thin bilayer
thickness and hence to increase the m-value of the polarizing supermirror.
3.	Performance test of Fe/Ge neutron polarizing
supermirror
An Fe/Ge neutron polarizing supermirror with
m = 6.2 was fabricated by an ion-beam sputtering system with dual bucket Ar+ ion sources. The layer sequence
was designed by the algorithm proposed by Hayter and
Mook [6]. To avoid a reduction in the saturation magnetization in thin Fe layers corresponding to qz >1.085 nm−1
(m > 5), we proposed a modified layer sequence, where
the minimum Fe thickness was set to 3.5 nm, whereas
the Ge thickness was reduced. This resulted in a total
number of layers of 10436 and total thickness of 32 μm.
The polarized neutron reflectivity (PNR) measurement
at room temperature was performed for the Fe/Ge polarizing supermirror under an external field of 40 kA/m.
The measured PNR profiles and polarization are plottedin Fig. 2. The spin-up reflectivity was higher than 0.70 for
qz < 1.302 nm−1 (m < 6) and the polarization was higher
than 0.93 for 0.217 ≤ qz ≤ 1.194 nm−1 (1 ≤ m ≤ 5.5). The
performance test of the neutron polarizing supermirror

Research and Development Highlights

showed that the FM interlayer exchange coupling contributed to the presence of the magnetization comparable to the bulk and resulted in a marked enhancementin the m-value larger than 6 [7].
4. Summary
The polarized neutron off-specular scattering
measurement revealed that the FM interlayer exchange
coupling occurred in the ion-beam sputtered Fe/Ge
multilayer when the Ge thickness was reduced to lessthan 2.2 nm. The FM interlayer exchange coupling contributed to the presence of the saturation magnetizationcomparable to the bulk. The Fe/Ge polarizing supermirror fabricated with the modified layer sequence proposed here showed a marked extension in the m-value
larger than 6. The bandwidth extended in this study is
not enough to cover a full spectrum available at the MLF.
The origin of the magnetic interlayer exchange coupling
across a semiconductor spacer has not been fully understood. Further study including this point is needed to
improve the performance of the polarizing supermirror
and to promote the science using polarized neutrons.
References[1] V.F. Turchin, Sov. J. At. En., 22 124 (1967).
[2] F. Mezei, Commun. Phys., 1 81 (1976).
[3] R. Maruyama et al., Nucl. Instrum. Methods Phys.
Res. A, 888 70 (2018).
[4] M. Hino et al., Physica B, 385-386 1187 (2006).
[5] M. Takeda et al., Chinese J. Phys., 50 161 (2012).
[6] J.B. Hayter and H.A. Mook, J. Appl. Crystallogr., 22 35(1989).
[7] R. Maruyama et al., J. Appl. Phys., 130 083904 (2021).

Figure 2.	Polarized neutron reflectivity profiles of
the Fe/Ge neutron polarizing supermirror
fabricated in this study. Spin-up and -down
reflectivities are plotted in red and blue,
respectively. The polarization is shown inblack.
R. Maruyama
Neutron Instrumentation Section, Materials and Life Science Division, J-PARC Center71

Neutron SourceNeutron Source

MLF Annual Report 2021

Neutron Source Section
1. Overview
At the beginning of fiscal year 2021, on April 5, thebeam power was raised to over 700 kW from 600 kW,
which was the highest level of beam power on record
for the long-term user program at the MLF. The stable
operation continued, but due to the humid and hot
weather in the summer, the beam power had to be decreased to 600 kW again from June 24 in order to increase the cooling capacity margin of the accelerator
devices. The beam operation ended on July 17, before
the start of the long outage.
As the beam power increases gradually to the final
goal of 1 MW, promotion of the radiation work safety,
especially in the maintenance period, becomes more
and more important. In order to check and review thecriteria for radiation work safety and procedures ofmaintenance works, sufficient maintenance period was
secured and parallel works that could increase the riskof radiation release or contamination were avoided toconcentrate on each maintenance task one by one. The
results of check and review were used to improve theplanning of maintenance works from the next year on.
These procedures led to the late start of the beam operation for the user program from January 15 in 2022.
After the beam operation resumed, the neutron
source continued its stable operation at 730 kW andthe average operational efficiency in fiscal year 2021
reached 95.9%.

2.	Pitting damage mitigation of the mercury target
vesselOn October 18, specimens were cut out from theforefront wall, the beam window, of the used target
vessel, which was operated with 740 kW at maximum,
to investigate the efficiency of technologies for pitting
damage mitigation, which involve the double walled
structure with a narrow channel and the microbubble
injection into the mercury flow as shown in Fig. 1. The
maximum damage depth on the bulk side of the innerwall specimen was less than 1 mm and the surface ofthe narrow channel side was almost intact, which wasa promising result for the stable beam operation withgreater beam power.
On November 1, the used mercury target vessel was
replaced with a new one with an improved structure of
the mercury flow channel. That is, the bubble generator
was installed at a position 92 mm closer to the beam
window than the former one to increase the bubble
number density near the beam window for promoting
the pressure wave mitigation effect. Improvement of themercury target design was further continued to install
the bubbler as closer to the beam window as possible torealize the long and stable target operation with a final
goal of 1 MW, which is shown in the following chapter.

Figure 1.	Cutting machine (top) and structure of the target
vessel (middle) and the surfaces of an inner wall
specimen (bottom).

74

MLF Annual Report 2021

Neutron Source

Figure 3.	Chilled towers of the 3NBT water cooling system.

Figure 2.	Engaging the gripper of a hoist with the hanger ofthe moderator & reflector assembly.

3.	Remote handling test of the moderator & reflector
assembly
The remote handling test of the moderator & reflector assembly was carried out for the first time since thebeam operation of the MLF started in 2008. The spare
assembly, which would be replaced with the present
one in a few years, was used for the handling tests. First,
the handling tests were carried out by hands-on in the
HENDEL building where was a non-controlled area. Thenthe spare assembly was transported to the MLF, andremote handling tests were conducted in the hot-cellusing the remote handling tools including the transportation cask equipped with a hoist and gripper in
it, as shown in Fig. 2. In 2021, the assembling and disassembling procedures of the decoupled moderator
were checked and successfully completed. The othercomponents of the assembly, such as the coupled andpoisoned moderators, and the reflector, would be tested
during the maintenance period in the next year.

4. Noticeable maintenance works
The maintenance work to replace a vacuum pumpof the gas process system, which is a crucial device forthe target replacement, was a significant task. It needed
special care to suppress the release of radioactive materials and the requirement was fulfilled through a wellprepared procedure plan, which is also shown in thefollowing chapter.
The cooling tower of the coolant water loop for thedevices of the 3 GeV proton beam transport line was
replaced to the chilled towers, shown in Fig. 3, as a countermeasure against aging deterioration. The increased
cooling capacity will contribute to a stable beam operation in the summer.

K. Haga
Neutron Source Section, Materials and Life Science Division, J-PARC Center75

Neutron Source

MLF Annual Report 2021

Optimization of Mercury Target Vessel Design to Extend
the Lifetime by Using Machine Learning
1. Introduction
In a mercury target for neutron sources, pulsed proton beams repeatedly bombard the flowing mercury
which is confined in a stainless-steel vessel (target vessel(Fig. 1)). The bombardments of the proton beams cause
instantaneous thermal expansion of the mercury which
generates pressure waves in the mercury. Cavitation
damage, which is induced by the pressure waves, is oneof crucial issues to determine the lifetime of the target
vessel. To reduce the damages, we developed a narrow channel structure [1, 2] and a technique to inject
the gas microbubbles into the flowing mercury by theswirl bubbler [3], which can reduce the pressure waves
inducing the cavitation damage [4]. The neutron source
continued its stable operation at 730 kW and the average operational efficiency in fiscal year 2021 reached95.9%. The beam power increases gradually to the final
goal of 1 MW.
On the other hand, the spent target vessels occupy
a storage area. Therefore, further reduction of the damage is required to extend the lifetime of the target vessel
and to reduce the generation frequency of spent target
vessels. The sufficiently small gas bubbles are required
to reduce the pressure waves because the natural frequency of the smaller bubbles is higher, and they can
respond to and absorb the instantaneous thermal expansion of the mercury. And to increase the gas volume
fraction of gas microbubbles is also effective to absorb
the thermal expansion and to reduce the pressure
waves [5]. The severe damaged area is the beam window where the proton beam is injected as show in Fig.1

Flow guide vanes
High heat deposi�onBeamwindow

Protonbeam

2. Design for optimization
Figure 1(a) shows the schematic of the original mercury target structure. Flow guide vanes are installed inside the target vessel so that distribution of mercury flowrate can be achieved to correspond with distribution ofheat deposition in mercury. The bubbler was installedon the inlet side. In the original design, 5 elements were
installed in one unit. However, the unit is bombarded
directly by the proton beam when the unit moves to thebeam window as shown in Fig. 1(a). Therefore, in the design for optimization, the unit was divided into 2 units asshown in Fig. 1(b). Each unit includes 3 elements. Figure 2
shows the bubbler element. In the optimization, the parameters shown in Fig. 1, 2 were used for the design variables for the machine learning. Here, P1 is the distanceof the bubbler unit B1 from the original position, Θ theangle of flow guide vane, D the Inlet diameter of the
bubbler element, θ the angle of the swirl blade, and De
the diameter of the throat in the bubbler element.

Swirl blades

Mercury
outletThroatOutletBubbler unit
Move

Mercury
inlet(a) Original design

Bubbler unit, B1
Bubbler unit, B2
ΘP1(b) Design for op�miza�on
Increase of volume frac�on of gas microbubbles

Figure 1.	Schematic of the mercury target vessel: (a) original
design, (b)design for optimization.

76

because heat deposition and generated pressure waves
are high. It is considered that the volume fraction of gas
microbubble near the beam window can be increasedby moving the bubbler closer to the beam window since
the injected gas bubbles rise due to buoyancy. However,the space near the beam window is restricted as shownin Fig. 1(a). Therefore, the bubbler design and setting
position as well as the flow guide vanes for the mercury
flowing pattern were optimized by means of a machinelearning technique to increase the volume fraction of
microbubbles near the beam window [6].

Mercury
inlet
Figure 2. Swirl bubbler element.

MLF Annual Report 2021

near the beam window (x 10 -3)

Volume fraction of gas microbubbles

440
Constraint condition

3

Flow rate, Q

30

Hg

Volume fraction
2

20

1

0
100

108.4 mmAngle of swirl bladein bubbler B1 :
θ1=64.7°

120

160

140

180

200

220

10

Flow rate of mercury (m 3/h)

3. Machine learning and optimization
To generate data for machine learning, 1000 casesof CFD (Computational Fluid Dynamics) simulations withbubble flow were performed by changing the design
parameters shown in Fig. 1, 2. Fluent ver. 19.2 [7] wasused for the simulation, and Realizable k-ε was used forthe turbulence model. As for the boundary condition,
the pressure difference between the mercury inlet andoutlet was set to 0.23 MPa which was decided according
to the capability of the mercury pump. The motion of
bubbles in mercury was modeled using a discrete phasemodel. Since the interaction between bubbles is not taken into consideration, the bubbles do not break up andcoalesce. Since the generated bubble size distribution
depends on the bubbler design and mercury flow speed
in the bubbler, the injected bubble size distribution waschanged based on the empirical formula [3].
Based on the simulation results, surrogate models
to predict the volume fraction of the gas bubble near
the beam window (objective function), the mercury flowrate and the generated bubble size (constraint conditions) were derived by Gaussian process. By using theobtained surrogate models, optimization to maximize
the objective function by means of the sequential quadratic programming was performed to fit the constraint
conditions. As of the constraint conditions, the mercury
flow rate was set to be over 36 m3/h to keep the temperature rise of the mercury and the target vessel similar
to or less than the original one. And bubble diameter
was set to less than 100 μm so that the gas bubbles can
respond to the instantaneous thermal expansion. Afterthe optimization, the CFD simulation was carried out by
using the optimized design variables for verification.
Figure 3 shows the volume fraction of gas microbubbles near the beam window and mercury flow rate
as a function of bubbler position, which is calculated byusing the obtained surrogate models. It is noted thatthe design parameters except for the bubbler position
are optimized values. As mentioned above, the volume
fraction is increased as the bubbler unit B1 moves near
the beam window. However, the mercury flow rate is decreased. Therefore, the optimized results for the bubbler
position did not show the nearest position to the beam
window.

Neutron Source0

Bubbler position, P1 (mm)Figure 3.	The volume fraction of gas microbubbles near the
beam window and mercury flow rate as a functionof the bubbler position.

4. Optimization result
As an optimization result, we developed the designof a mercury target vessel that can increase the volume
fraction of gas microbubbles near the beam winodow
by ca. 2.5 times higher than the original design. As forthe damage, an empirical formula to estimate the damage depth was derived based on the result of off-beam
test [8] and the relationship between the observed
damage and operational condition of the target was acquired. And the effect of the gas injection rate on the reduction of the pressure waves was measured [4]. Basedon these empirical formulae and relationships, the optimized target vessel will endure for 2-year operation at
1 MW. The fabrication of the target vessel based on the
optimized results will be completed in fiscal year 2023.
References[1] K. Haga et al., JPS Conf. Proc., 8 051008 (2015).
[2] T. Naoe et al., Mat. Sci. Forum, 1024 111 (2021).
[3] H. Kogawa et al., J. Nucl. Sci. Tech., 52 1461 (2015).
[4] H. Kogawa et al., J. Nucl. Sci. Tech., 54 733 (2017).
[5] K. Okita et al., J. Fluid Sci. Technol., 3 116 (2008).
[6] H. Kogawa et al., JAEA-Technology 2022-023, (2022).
[7] ANSYS Inc., ANSYS Fluent Theory Guide, Release19.2 (2018).
[8] M. Futakawa et al., J.Nucl. Sci. Technol., 40 895 (2003).

H. Kogawa1, T. Wakui1, M. Futakawa2, T. Naoe1, and K. Haga1
Neutron Source Section, Materials and Life Science Division, J-PARC Center; 2Invited Researcher, J-PARC Center

1

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MLF Annual Report 2021

Radiation Safety Countermeasures for Pump Replacementof the Off-gas Processing System
1. Introduction
An off-gas processing system is adopted in the MLF
to remove radioactive material, produced by mercury
spallation reactions, from the cover gas and purge gas
used in the mercury circulation loop. Figure 1 shows aphoto of the off-gas processing system. The radioactive
gas is transferred to this system with a vacuum pumpin advance of the maintenance works of the mercury
circulation loop. The pump is also used to form an inflowof air to suppress the release of gaseous radioactivity
during the replacements of a target vessel, pressuregauges, etc. Those gases are stored, processed, and finally released to atmosphere from the stack.
We replaced one of the vacuum pumps, which had
been used for 14 years as a backup of the main pump,in a viewpoint of preventive maintenance. Here, we report how we secured the radiation safety of the vacuum
pump replacement work in which the control of radioactive gas release was thought to be a challenge.
2. Method
Radioactive gas passes through the vacuum pump,thus it is concerning that the radioactivity remaining in thepump could be released from the opening of the piping
during the pump replacement. To minimize the release, we
enclosed couplings of piping connection parts with readymade plastic bags with gloves named “glove bags”. To

ensure airtightness, we sealed the glove bags by welding
the opening parts and taping pipe-penetrating parts withvinyl tape. We filled the glove bags with dry air through asmall nozzle with a valve and confirmed that no air leaked
from the bags.
We also set a “barrier box” made by welding polyvinyl
acetate (PVAC) sheets to cover the pump and the glove
bags. The inner area of the barrier box was exhausted by
local ventilation to prevent internal radiation exposure ofworkers. We checked the air flowing into the box from theopening on the workers’ side. Figure 2 shows a photo of thevacuum pump in the barrier box before the replacement.
The radioactive gas is released to the barrier box
when the glove bags are removed and is exhausted withthe local ventilation. Based on experiences of previous replacements of vacuum pumps and other instruments, we
decided to transfer the gas in the glove bags to the off-gas
processing system before dismantling the bags. For such
purpose, we connected a tube to each nozzle of the glove
bag. It contributed to suppressing not only the internal exposure of workers but also the release of radioactivity to
the local ventilation as much as possible.
We assigned two workers and one supervisor toapproach the working area. These three persons were
equipped with demand-type airline respirators and vinyl anorak suits to minimize inner exposure not only bybreathing but also through skin absorption. Two teams of

Figure 1. Photo of the off-gas processing system.
Figure 2.	Photo of the vacuum pump in the barrier box before the replacement.

78

MLF Annual Report 2021

workers relayed the work to lighten their loads because
the expected total working time with such equipment was
too long. During the work, the radioactivity concentrations
both in the barrier box and around the workers’ respiration
area were monitored.
3. Procedure
The working procedure is mentioned below and illustrated in Fig. 3.
(1)	Covering the couplings with the glove bags (bythe day before).
(2) Demounting the couplings.
(3) Moving the pump back to make a space.
(4) Closing the 4 openings with blank flanges.
(5)	Evacuating gas in the glove bags to the off-gas
processing system.
(6) Cutting the glove bags.
(7) Removing the old pump.
(8)	Covering both openings of newly installed metallic valves and the pipes with glove bags.
(9)	Connecting the metallic valves and the pipes withcouplings.
(10) Leak checks.

Neutron Source(11) Removing the glove bags.
(12) Connection of a new pump (on the next day).
4. Result
The pump replacement was carried out on
September 27. Increases in the monitored radioactivity concentrations in the barrier box and the respiration
area were much lower than the predicted by prior estimation. The workers’ inner exposures were less than thelower detection limit. Contamination around the working area after the replacement was not detected.
We performed a test run of the new pump andfound no problems.
On a later day, we put the used pump into a stainless-steel double-walled container and encapsulated it
by welding an outer container.
5. Summary
We prepared the glove bags, the evacuation of gas inthem, the barrier box, the demand-type airline respirators,
and vinyl anorak suits for radiation safety. No workers’ inner exposure was detected, and the vacuum pump was
successfully replaced.

Figure 3. The procedure of the vacuum pump replacement.

S. Takamiya and T. Kai
Neutron Source Section, Materials and Life Science Division, J-PARC Center

79

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MLF Annual Report 2021

Neutron Science Section
1. Introduction
The mission of the Neutron Science Section (NSS)
is to lead scientific research as a world neutron center,build and maintain state-of-the-art instruments, organize collaborative research, support user programs, andcarry out our own scientific research. COVID-19, still
being the rage across the globe, disturbs those activities in the facility, we have to keep making significant
efforts to maintain or even to improve the activities andthe scientific work. For most users from abroad, it is still
difficult to visit Japan because of the COVID-19 restrictions, so many proposals have been canceled and therest have been conducted as deputized experiments by
the beamline scientists.
2. User program
The proposal round of 2021A,merged with that of
2020B, has been called but no new long-term proposals had been called for 2021 due to delay in conducting
the approved ones for 2018L to 2020L. In the period of
2021B, we received 338 neutron proposals, including
short-term, one-year, NUP (new user promotion) andpost deadline proposals. Among them 137 have been
approved. Although the number of submitted proposals
showed an abrupt drop in the 2020A, it is now recovering or even exceeding the submissions for 2020. The
breakdown of the distribution of applicant affiliations
are summarized in Fig. 1.
3. Instruments up to date
Initially, 23 beamlines (BL) for neutron experimentwere designed for future instruments in the MLF and 21
are under operation at moment. The MLF beam operation started officially in May 2008, 14 years have alreadypassed particularly for BL in the early stage of the MLF(day-one instruments). All the BL, infrastructures, andequipment must be kept maintained, specifically the BL
were required to be upgraded for the most advanced
experiments. Here we report on one of those unremitting endeavors of beamline works.
BL17 is the neutron reflectometer (NR), which enables us to study mechanisms and functions of thin film
material by revealing surface structures and buriedinterfaces. To prove dynamical phenomena varying intime, it was necessary to shorten the measurement time
which is longer in conventional NR from several tens ofminutes to few hours for one measurement. The BL17
team developed a new data processing method basedon deep learning, which can successfully eliminate
statistical noise from the raw data obtained in a rather
short time like one tenth of the conventional NR [1]. It
means that we can effectively extract the signals out ofshort measurement data and explore dynamic behaviorof surface and interface (Fig. 2).
The new data treatment method, such as machinelearning or deep learning, can be classified into the artificial intelligence (AI) technology. The huge volume ofdata created on a daily basis in the MLF operation would
bury a human researcher. But the AI technologies cantake that data and quickly turn it into meaningful information. This can be the “must” technique for the futuredata analysis in the MLF.

Figure 1. Distribution of applicants’ affiliation for proposal round 2021B.

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Figure 2.	Schematic illustration of deep learning to remove the noise from the neutronreflectometry (NR) data. The characteristics of the noise in NR measurements isdisclosed by the deep learning by a convolutional neural network using a data setof the NR data with a statistical noise and the supervising NR data without noise.

4. Other activities
As mentioned above, it had been over 14 years since
the MLF operation was started. We always need to lookat the future vision of the MLF to continuously step forward the facility and neutron science. In order to establish a clear vision of the MLF, we initiated “MLF2030”, theseries of group discussions about MLF’s future plans,branched into three scientific (or instrumental) groupsof fundamental instruments, elastic instruments and inelastic instruments. In addition to the scientific groups,
some specific device groups of neutron polarization,
detector, vacuum chamber, and choppers had independently summarized their future direction.
Australian Nuclear Science and Technology
Organization (ANSTO) is one of the most significant
national infrastructures for research in Australia, operating the research reactor OPAL. The MLF has arranged
cooperation on research and development in neutronscience with ANSTO since 2016. In 2021, the arrangement has been extended for the next five years and was
expanded to include the registered institute CROSS.
At the beginning of the renewal, collaborative scientific and technical series of workshops were held online,
and the following topics were discussed, 1) dynamics,
2) sample environment, 3) reflectometry, 4) small angle
diffraction, 5) structural analysis, 6) neutron polarization,7) deuteration, 8) imagining technique, 9) computation,10) industrial. All the workshops were summarized on
January 13.
Also, the Workshop on “Neutron and Muon Methods

for J-PARC MLF Users in Korea” was hosted by J-PARC
in April. After reporting on the present status of the
MLF, including neutron and muon instruments, several
new ideas and aspects of science and method were
presented.
A few of our yearly activities, which we had to skip
in FT2020 due to the pandemic, have been re-organized as online events in FT2021. Quantum Beam Science
Festa, which is a domestic conference gathering users
of several facilities providing different type of quantum
beams including neutron, was successfully opened online in March 2022. The 5th-Neutron and Muon School,
which is an international school providing lectures by
outstanding experts over the world and experimental
practices, was also held as a virtual event sponsored by
IINAS (Inter-Institution Network for Accelerator Science)program of KEK in December.
5. Award
Prof. Hideki Seto received the Science Prize of theJapanese Society for Neutron Science (JSNS) for the application and development of neutron scattering to soft
matter research. Dr. Takashi Ohhara won the ResearchAward from Crystallographic Society of Japan for the
structural chemical study with hydrogen atoms as a
key by high precision single-crystal neutron diffraction
method.
Reference[1] H. Aoki et al., Sci. Rep., 11, 22711 (2021).

Y. Kawakita1, T. Yokoo1,2, and M. Nakamura1
Neutron Science Section, Materials and Life Science Division, J-PARC Center; 2Institute of Materials Structure Science, KEK

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BL01: 4D-Space Access Neutron Spectrometer 4SEASONS
1. Use trends
4SEASONS is a direct-geometry time-of-flight neutron spectrometer for thermal neutrons, and one of the
Public Beamlines in the MLF [1]. In 2021, 8 General Use(short-term) proposals, 1 CROSS Development Use proposal, and 1 Instrument Group Use proposal were approved for 4SEASONS. Due to the COVID-19 pandemic,
the expiration dates of proposals in previous proposalrounds were extended and the call for proposals in the
2021A proposal round was canceled, which resulted in
the decrease in the number of the approved proposals. 88% of the General Use proposals were submitted
by international users. Conversely, 5 2020B reserved
proposals and 3 2021B reserved proposals were given
beamtime to compensate for the vacancy. Some of theusers’ experiments, for which the research group had difficulties visiting the MLF due to the pandemic restrictions, were carried out by the instrument group insteadof the research group. 67% of the submitted proposals
were in the field of magnetism, while the rest of themtargeted phonons and other atomic vibrations. 9 peerreviewed papers were published in 2021.
2. Instrument upgrade
Remote control using IROHA2: 4SEASONS uses thesoftware IROHA2 [2] to control devices remotely via a
web-based interface. In FY2021, we newly made the following devices controllable via IROHA2: the oscillatingradial collimator (ORC), the top-loading GM refrigerator,
and the LakeShore 336 temperature controller. In addition, we updated the IROHA2 driver for the Fermi chopper whose controller had been updated, because it wasincompatible with the new controller. We also upgraded
the IROHA2 from the old Python 2 based version to the
new Python 3 based one.

Oscillating Radial Collimator: 4SEASONS uses the
ORC to suppress scattering from sample environment
devices [3]. The collimator blades are made of Cd-plated
aluminum plates. Recently, however, deformation of themetallic blades and neutron scattering at the blades inthe direct beam became serious problems. Then, we developed 10B4C-painted Kapton blades. We tested 6 new
blades which were installed around the direct beampath. The plastic-based 10B4C blades showed less deformation compared with the metallic ones. On-beam tests
with the top-loading cryostat showed that the 10B4C
blades suppressed the background more effectively at
500 meV, and Bragg peaks of Cd observed with the Cd
blades at low energies (~10 meV) were disappeared.
However, the 10B4C blades produced more intense incoherent scattering background, which was probably
caused by hydrogens in the resin (Fig. 1). We are considering the use of the 10B4C blades at positions apart fromthe direct beam path.
Beam optics: Last year, we replaced a rectangularbeam collimator just before the sample with a rotary
optics exchanger. In FY2021, we prepared a Soller collimator whose blades are made from sintered B 4C asan exchangeable optics. We evaluated the transmission and the background of the Soller collimator with aneutron beam (Fig. 2) and found that the transmission
was consistent with an analytical calculation. However,the collimator caused substantial background at highenergies, though the background at low energies was
reduced. Interestingly, the background at high energies
appeared when the beam narrower located upstreamof the Soller collimator was widely open. This result suggests that the background was caused by scattering at
the incoming part of the collimator.
Detectors: 4SEASONS utilizes 2.5-m-long position

Figure 1.	Color maps of powder-averaged background intensity as a function of the momentum transfer Q and the energy transfer
E at Ei = 500 meV [(a) and (b)] and Ei = 20 meV [(c) and (d)] with the Cd blades [(a) and (c)] and the 10B4C blades [(b) and (d)].

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Figure 2.	(a) Comparison of the calculated and observed transmission of the Soller collimator. The observed values were estimatedby the scattering intensity of a Bragg peak of a Al2O3 polycrystal. (b) and (c) Powder-averaged intensity as a function of Q
of empty measurements at Ei = 300 meV. (b) With the Soller collimator (green) and the rectangular collimator (blue). (c)With the Soller collimator when the aperture of the upstream beam narrower was 20 mm (width) × 48 mm (height) (blue),
48 mm (width) × 20 mm (height) (green), and 20 mm (width) × 20 mm (height) (red).

sensitive 3He detectors to cover effectively a wide solid
angle. However, this kind of detector tends to cause
pile-up when it detects strong neutron counts [4]. To
mitigate the problem, we consider using a new detector
electronics module, called NEUNET-C [5]. This electronics module can analyze pulse width of the signal as wellas pulse height, and we expect it can filter out pile-up
signals. Then, we performed a preliminary test measurement by applying a prototype of NEUNET-C. The result
was promising. We will carry out the test again to evaluate the effect of the filtering in more detail next year.
Utilities: The cooling water supplying ports and helium gas recovering ports of 4SEASONS are placed on thefloor. This position is inconvenient for the use of sample
environment devices, because the hatch for the sample
environment devices is located on the shielding houseand is far from the ports. To eliminate the inconvenience,in FY2021, we added a utility rack hosting ports of waterand helium gas on the shielding house (Fig. 3).
Acknowledgements
We thank K. Inoue and W. Kambara for their support and advice. The on-beam test of NEUNET-C was
performed with the help of S. Sato. The instrumentation
works described here were supported by the engineersof the Neutron Science Section and the Technology
Development Section of the MLF.

Figure 3.	Utility rack of cooling water andhelium gas recovering lines addedon the shielding house.

References[1] R. Kajimoto et al., J. Phys. Soc. Jpn. 80, SB025 (2011).
[2] T. Nakatani et al., JPS Conf. Proc. 8, 036013 (2015).
[3] M. Nakamura et al. JPS Conf. Proc. 8, 036011 (2015).
[4] D. Raspino et al., 2015 IEEE Nuclear Science
Symposium and Medical Imaging Conference, doi:
10.1109/NSSMIC.2015.7581915.
[5] S. Sato et al., EPJ Web of Conferences 231, 05004(2020).

R. Kajimoto1, M. Nakamura1, K. Kamazawa2, Y. Inamura1, K. Iida2, K. Ikeuchi2, and M. Ishikado2
Neutron Science Section, Materials and Life Science Division, J-PARC Center; 2Neutron Science and Technology Center, CROSS

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Current Status of BL02 DNA in 2021
1. Introduction
DNA is a TOF type Si crystal analyzer backscattering
spectrometer installed at the Japan Proton Accelerator
Research Complex (J-PARC) spallation neutron source [1, 2].
DNA uses a pulse-shaping chopper to extract sharp
pulsed neutrons from a strong but broad spectrum of
the coupled moderator, which achieves μeV-order energy resolution in wide energy transfers of meV-order.
Furthermore, the signal-to-noise ratio at DNA reaches~105, which makes it possible to cover a variety of research fields with small scattering amplitudes or withsmall quantities of samples (of the order of milligrams).
The number of peer-reviewed papers from DNA in
2021 was 18, including 8 proceedings papers, which isdouble the average since 2017. BL02 was also used forone master thesis in 2021. In addition, Mr. Yuki Hirota,
doctoral student from Setsunan University stayed at
MLF as a fellow of advanced science for 3 months toanalyze DNA data.
2.	User Program in the periods 2020A and 2020B–
2021A
In 2021, 33 (2020B–2021A) and 24 (2022A) General
Proposals (GP) were submitted to BL02. 13 GP, and 5 GPs
including 2 New User Promotions (NUP) were approvedfor 2020B–2021A and 2021B, respectively. The portionof approved beamtime from all requested beamtime
was 38% for 2020B–2021A and 20% for 2021B. The competition rate was high: 2.75 and 4.8 for 2020B–2021A
and 2021B, respectively. Additionally, 2 and 5 reserved
proposals were also conducted in 2021A and 2021B,
respectively.
Due to the pandemic situation, two experiments
were conducted by BL02 staff without users. But two
foreign groups could come to MLF for experiments withthe relaxation of border restrictions. In addition, four
General Proposal (Long Term) (hereafter LTP) Program,proposals ran at BL02 in 2021.
3. Beamline activities
Additional Si311 analyzer mirrors were installedat scattering angle (2θ) of –150° < 2θ < –126°. Now,
Si311 analyzers cover momentum transfer from 1.79 to
3.70 Å–1. We also replaced the damaged Si111 analyzer
mirrors at scattering angle (2θ) of 6° < 2θ < 30°.
At BL02, the superconducting magnet prepared in
the MLF as the common-use equipment could not be
used due to its radius (800 mm-φ) that was larger than86

our access-port flange (420 mm-φ). However, the DNA
spectrometer potentially enables us to investigate amagnetic excitation with a small (~μeV) gap, that small
gap and its magnetic field dependence are often essential for characterizing the quantum magnetic systems. To
apply a magnetic field to samples, we have introduced
a new superconducting magnet suitable for BL02
(Fig. 1). The new magnet is designed as follows: (1) The
maximum magnetic field is 3.5 T, (2) The temperature
range is 300 ~ 1.5 K, which comes down to 100 mK withthe dilution refrigerator option, (3) The coils of the magnet are coated by B4C tiles to reduce the background.
Taking into account that the magnetic field of 1 T produces a change in energy about 60 μeV for S = 1/2 spin,
the max field of 3.5 T will be enough to investigate themagnetic field dependence of such a μeV-order gap at
DNA. Now, we are proceeding with the commissioningof this magnet, and plan to make it available with user
experiments next year.
At BL02, aqueous solutions are often measured inpure Al and alloyed Al sample cells. Focusing on the interaction between the container and the aqueous solution, the corrosion susceptibility of Al and its alloys wasinvestigated using various treatments and comparedto other candidate materials with lower chemical reactivity [3]. QENS measurements of empty sample cells
fabricated with these materials were also performed toevaluate their contribution to the QENS profile. This is
expected to reduce the possibility that chemical interactions between the Al surface and the sample, promoted

Figure 1.	Photographs of the superconducting magnet suitable for BL02. (a) whole view, (b) coils of magnet
covered by B4C tiles.

MLF Annual Report 2021

by corrosive materials or specific pH conditions, could
compromise the integrity of the cell and interfere withQENS experiments.
As denoted in the introduction, BL02 are used in avariety of scientific fields, which requires various sample
environments (SE’s) including cryostat, furnace, magnet,
vapor-control system, etc. To reduce background fromvarious SE, we have developed oscillating radial collimators. Figure 2 shows the background with and without
radial collimator for a 2K cryostat. The split elastic line
at E ~ ±AQ2 is scattering from the wall of SE, which iseliminated with a radial collimator. We have two radialcollimators with different blade lengths, 56 and 76 mm,
which reduce background at r > 47 mm and 30 mm,
respectively.
As the neutron source becomes more intense, themeasurement time per sample becomes shorter andthere is a high demand for automation of measurements. We are developing RABBIT, a rotating automatic
sample changer that can install 20 samples. This will
enable the effective measurement of a large numberof samples and facilitate QENS experimental planning
based on new ideas.
We have been working on the problem of N2 beam
monitor’s aging for several years. By checking the pulseheight spectrum, we found that the peak shifted to thelower channel side, especially after radiation to strong
neutron beam, suggesting decomposition of the converter gas. We plan to replace the converter gas CF4 with

Figure 2.	Background from the cryostat with and without radial collimator (Rad. Col.) on Q (horizontal)-E (vertical) map.

Neutron Science

another gas. In addition, in 2020, we found that the TOF
spectrum was shifted when the beam monitor wasmeasured at the sample position. To study these shifts
in detail, we have developed new monitors to be used at
the sample position. We successfully obtained the TOF
spectrum with new monitors under various conditions.
We are currently developing software that would allow
these new monitors to be incorporated into DNA’s data
reduction.
As for the software development, 4D mapping of
S (Q, ω) by rotating a single crystal sample was performed for the first time at BL02 in 2020. We have modified the 4D S (Q, ω) visualization software D4mat so thatit can be used with BL02. In addition, we tested kernel
density estimation methods to improve the accuracyof the QENS fitting with MLF’s Computational team.
Although it still takes time, the kernel density estimation method still improves the error bar by half for preliminarily fits.
4. Other activities
To accommodate the increasing number of SE
equipment, the floor around the BL02 hatch has been
expanded.
5. Future plans
We will proceed with the further replacement ofdamaged Si111 analyzer mirrors. We will also replace thefocusing mirror with one with higher reflectivity, whichis expected to enhance the neutron beam flux by ~20%.
At the same time, the jacket of the focusing mirror will
be changed to a non-magnetic one, which is necessary
for the use of the BL02 magnet.
References[1] Kaoru SHIBATA et al., JPS Conference Proceedings, 8(2015) 036022.
[2] Y. Kawakita et al., EPJ Web of Conferences 272 (2022)
02002.
[3] T. Tominaga et al., J. Appl. Cryst. 54 (2021) 1631.

Y. Kawakita1, M. Matsuura2, T. Yamada2, T. Tominaga2, H. Tamatsukuri1, and H. Nakagawa1,3
Neutron Science Section, Materials and Life Science Division, J-PARC Center; 2Neutron Science and Technology Center, CROSS; 3Materials
Sciences Research Center, JAEA

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IBARAKI Biological Crystal Diffractometer iBIX
1. Introduction
Neutron single-crystal diffraction is a powerful method for obtaining structural information, especially for lightatoms. Because understanding the enzyme chemistry ofproteins at the atomic level requires the visualization ofhydrogen atoms at active sites and remote residues, cofactors, substrates, and water molecules, it is particularly
important to obtain precise information on the positionsof the hydrogen atoms in biological macromolecules. The
complementary use of neutron diffraction data, which
includes more information on hydrogen atoms, and
X-ray diffraction data, which includes more information
on non-hydrogen atoms (such as C, O, N, and S etc.), allows us to obtain structural information on all atoms in
the protein. The IBARAKI biological crystal diffractometer,
iBIX, is a high-performance TOF neutron single-crystal diffractometer [1, 2]. It is designed to elucidate the hydrogenatoms, protonation states, and hydration structures of biological macromolecules. In 2019, the iBIX diffractometer,
equipped with 34 detectors, was available for user experiments on organic compound, biological macromolecules,
and polymer samples, supported by the Frontier ResearchCenter of Applied Atomic Sciences, Ibaraki University. The
specifications of iBIX are shown in Table 1.
Table 1. Specifications of iBIX
Moderator

CoupledRange of wavelength ofincident neutron (Å)
Neutron intensity
2(n/s/mm ) (@1 MW)

0.7 ~ 4.0 (1 frame)nd
4.0 ~ 8.0 (2 frame)

L1 (m)40

L2 (mm)491

Solid angle of detectors(% for 4π str)
Detector covered region(deg.)
2

Detector size (mm )0.7 × 106

22.0
15.5 ~168.5
133 × 133

2

88

st

Detectors pixel size (mm )0.52 × 0.52

No. of detectors

34

Sample environment

Gas flow type cooling system
by N2 gas (~100 K)
Heating system for polymer
sample (~600 K)
Tensile loading system forpolymer sample (~200 N,~90 mm, 1~1000 mm/sec)

2. Current status
In 2021, J-PARC was operated regularly at an accelerator power of 700 kW. We were able to collect a full data setof biological macromolecules for neutron structure analysis with around 2.0 Å resolution in less than one week byusing the iBIX at the accelerator power of 700 kW. The
maximum unit cell size was 135×135×135 Å3. The typical crystal volume of the sample measured by the iBIX wasaround 1.0 mm3.
4 test measurements for a J-PARC proposal (2021A: 1,
2021B: 3), 11 test measurements for a proposal of an innovative research project of the Ibaraki Neutron Beamline(2021A: 6, 2021B: 4) and 6 test measurements for a
proposal of a leading research project of the Ibaraki
Neutron Beamline (2021A: 3, 2021B: 3) were performed
using the iBIX. And then, 6 proposals were moving onto the full data collection for neutron structure analysis.
3. Maintenance and development
Temperature control of the experimental hatch isimportant to constantly maintain detector sensitivity because the photomultiplier tube of our scintillator
detectors is very sensitive to temperature change. The
temperature control system with a water-cooled typeair-conditioning package was installed in our experimental hatch as shown in Fig. 1. The total operation timeof the water-cooled type air-conditioning package has
already exceeded the service life. We replaced the watercooled type air-conditioning package in FY2021.
Temperature change inside the experimental hatch
was recorded for several days after the replacement of
the air-conditioning package. From this result, we confirmed that it met the required performance specifics.
The temperature control system is already available foruser experiments. Several parts of the detectors alsoneed replacement due to age deterioration. In FY2021,
we replaced the encoder modules and read out modules of some detectors. The data reduction software“STARGazer” has also been updated continuously in order to become more user friendly.
4. Future plans
It has been over 10 years since the iBIX instrument was
installed on the beamline, so some of the beamline instruments have been already replaced in the last few years due
to age deterioration. One of the remaining instruments for
replacement is the disk-chopper. The cumulative time ofservomotor rotation has exceeded the service life. Next

MLF Annual Report 2021

year, we will replace the servomotor and the servo amplifier of the disk chopper. In order to enable remote accessfor the measurement, the measurement software of iBIX
should be updated based on the standard instrument control software framework of the MLF, IROHA2.
In the near future, the accelerator power of J-PARC will
increase to about 1 MW. iBIX should be available regularly
for full data-set measurement of samples with a volume ofless than 1 mm3. However, the sample size is still large, andthe measurement time is still long, especially for the users.
We would like to reduce the difficulties of preparation oflarge crystal as much as possible. In other words, it is necessary to further improve the measurement efficiency of iBIX
by developing the beamline instrument. We have started
to consider the possibilities for improvement of the measurement efficiency. For example, installation of additional
detectors, increase of beam divergence by insertion of asuper mirror, changing the distance between the sample

Neutron Scienceand detector surface, improvement of the chopper instrument, development of a high efficiency measurement
method and so on. We will continue to develop both thesoftware and the beamline instruments to improve themeasurement efficiency and the accuracy of intensity
data obtained from smaller protein samples in order toensure that we have one of the highest performance
single crystal neutron diffractometers for biomacromolecules in the world.
References[1] I. Tanaka, K. Kusaka, T. Hosoya, N. Niimura, T. Ohhara,
K. Kurihara, T. Yamada, Y. Ohnishi, K. Tomoyori and T.
Yokoyama, Acta Cryst., D66 1194 (2010).
[2] K. Kusaka, T. Hosoya, T. Yamada, K. Tomoyori, T.
Ohhara, M. Katagiri, K. Kurihara, I. Tanaka and N.
Niimura, J. Synchrotron Rad., 20 994 (2013).

Figure 1. The temperature control system with the water-cooled type air-conditioning package.

K. Kusaka, T. Yamada, N. Yano, T. Hosoya, and I. Tanaka
Frontier Research Center for Applied Atomic Sciences, Ibaraki University

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Development of a LaBr3(Ce) Scintillator System for
Detecting Prompt Gamma Rays at ANNRI
1. Introduction
Prompt gamma rays emitted from the neutron capture reactions can be used for the determination of elements contained in interesting samples and reaction
rates of nuclei for the broad purpose of research in several scientific fields, such as geology, archaeology, earthscience, industry, environmental science, astrophysics,
and nuclear data [1-4]. Therefore, the intensive work todevelop techniques for detecting gamma rays in higher
counting rate and higher efficiency has continued for
decades. However, background gamma rays (noise)emitting from the impurities contained in samples sometimes impede the quantification of gamma rays emittingfrom interesting elements (signals). Here, a lanthanum
bromide (LaBr3(Ce)) crystal is well known to have the features of high-energy resolution and light output within ashort decay time. Thus, we have been developing a new
gamma-ray spectrometer system using the LaBr3(Ce) at
the Accurate Neutron Nucleus Reaction Measurement
Instrument (ANNRI) of the Materials and Life Science
Experimental Facility at Japan Proton Accelerator
Research Complex (J-PARC) [5, 6] to meet the expanding demands from the scientific fields for quantificationof the gamma rays with better signal-to-noise ratio.
2. Set up and experiments
Figure 1 shows the photograph of the LaBr3(Ce)scintillator system and a neutron beam duct made ofcarbon fiber. Inside this beam duct, air can be evacuated or purged by He-gas to prevent neutron scattering
events. The samples are set inside the beam duct utilizing the sample holder made by Teflon. The LaBr3(Ce)crystal size is 89 mm and 101.8 mm in thickness, whichis covered by the shields to prevent the backgroundgamma rays and neutrons B-doped polyethylene, Pb
and LiF-doped polyethylene.
In 2021 and 2022, an experiment was performed totest the performance of the LaBr3(Ce) scintillator system.
The proton beam power was approximately 730 kW. All
our samples had a shape of a pellet wrapped with afluorinated ethylene propylene (FEP) film which is neutron-insensitive. A 204Pb metal of 87% purity and 1.84 g
in weight was used as a sample. In addition, 197Au, C, andB samples were measured for energy calibration, estimation of the neutron scattering influence, and estimationof the incident neutrons.
90

Figure 1. LaBr3(Ce) scintillator system installed at ANNRI.

3. Results
Figure 2 shows the gamma-ray energy spectra for
204
the Pb sample obtained by the LaBr3 scintillator system indicated by the red line and the energy spectrum
obtained by the NaI(Tl) detector equipped at ANNRI forcomparison (indicated by the black line) [7]. After calibrating the gamma-ray energies with 60Co and the intrinsic ratio activity of the LaBr3(Ce) scintillator, several
gamma-ray peaks of 204Pb were observed which the
NaI(Tl) detector could not resolve.
4. Conclusion
We have tested the performance of the developing
LaBr3(Ce) scintillator system at ANNRI in J-PARC/MLF using an intense pulsed neutron beam. The result showsthat the LaBr3(Ce) scintillator system has a higher energy
resolution using 204Pb compared with that of the NaI(Tl)scintillator system at the ANNRI. The hereafter obtained
data of the Carbon, 204Pb, and blank samples will be
used for data corrections as follows: the scattering

MLF Annual Report 2021

Neutron Science

Figure 2.	Pulse height spectra obtained with the LaBr3(Ce) (red line) and NaI scintillator(black line) systems.

component and the self-shielding effect in the samples.
This analysis is now in progress.
This work was supported in part by Grants-in-Aid for
Scientific Research (JP).
References[1] Y. Toh, Y. Murakami, K. Furutaka, A. Kimura, M. Koizumi, K. Hara, T. Kin, S. Nakamura, H. Harada, Appl.
Radiat. Isot., 70 984 (2012).
[2] H. Harada, S. Goko, A. Kimura, M. Ohta, M. Oshima,
F. Kitatani, Y. Toh, K. Furutaka, T. Kin, M. Koizumi, S.
Nakamura, M. Igashira, T. Katabuchi, M. Mzumoto,
T. Ohsaki, J. Hori, T. Fujii, K. Takamiya, J. Goto, Y. Kiyanagi, K. Kino, M. Furusaka, F. Hiraga, Y. Kamiyama,
J. Korean Phys. Soc., 59 1547 (2011).
[3] K. Kino, M. Furusaka, F. Hiraga, T. Kamiyama, Y. Kiyanagi, K. Furutaka, S. Goko, H. Harada, M. Harada,

T. Kai, A. Kimura, T. Kin, F. Kitatani, M. Koizumi, F.
Maekawa, S. Meigo, S. Nakamura, M. Ooi, M. Ohta,
M. Oshima, Y. Toh, M. Igashira, T. Katabuchi, M. Mizumoto, Nucl. Instrum. Methods Phys. Res. A, 626 58(2011).
[4] Y. Toh, M, Ebihara, A. Kimura, S. Nakamura, H. Harada,
K. Y. Hara, M. Koizumi, F. Kitatani, K.; Furutaka, Anal.
Chem., 86 12030 (2014).
[5] Y. Ikeda, Nucl. Instrum. Methods Phys. A, 600 1(2009).
[6] F. Maekawa, M. Harada, K. Oikawa, M. Teshigawara,
T. Kai,T S. Meigo, M. Ooi, S. Sakamoto, H. Takeda,
M. Futakawa, T. Kato, Y. Ikeda, N. Watanabe, T. Kamiyama, S. Torii, R. Kajimoto, M. Nakamura, Nucl.
Instrum. Methods Phys. Res. A, 620 159 (2010).
[7] M. Igashira, Y. Kiyanagi, M. Oshima, Nucl. Instrum.
Methods Phys. Res. A, 600 332 (2009).

M. Segawa, M. Maeda, Y. Toh, S. Endo, S. Nakamura, and A. Kimura
Nuclear Science and Engineering Center, JAEA

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Status of Fundamental Physics Beamline BL05 (NOP) in 2021
1. Introduction“Neutron Optics and Physics (NOP/ BL05)” at the
MLF in J-PARC is a beamline for studies in the field offundamental physics. The beamline is divided at the
upstream into three branches, the so-called Polarized,
Unpolarized, and Low-Divergence branches, used in different experiments in a parallel way [1, 2].
A neutron lifetime measurement is conducted at
the Polarized beam branch with a spin flip chopper.
Pulsed ultra-cold neutrons (UCNs) by a Doppler shifter
are available at the Unpolarized beam branch. At the
Low-Divergence beam branch, the search for an unknown intermediate force is performed by measuring
neutron scattering with nano particles. The beamline isused also for R&D of optical elements and detectors.

it to 1 s. The largest source of systematic uncertainty isundefined background. Research is underway to resolve
this background event.
3.	Development of a neutron detector with highest
spatial resolution with nuclear emulsion
Nuclear emulsion plates are used as detectors that
can achieve high positional resolution in the fields ofnuclear and particle physics. N. Naganawa of Nagoya
University and colleagues developed an emulsion detector for neutrons that can achieve a positional resolution of <100 nm [6]. The emulsion detector consists of10
B sputtered on a silicon substrate and coated with afine-grained nuclear emulsion. After the developmentof the exposed detector, tracks from 10B layer observed
via an optical microscope could be reconstructed, andthe starting points from the 10B layer (reaction points)
were obtained with higher resolutions (minimum of
10 nm).

Counts [1/s/bin/MW]

2. Measurement of the neutron lifetime
The decay of neutrons is closely related to themechanism of the synthesis of elements in the universe
and to particle physics. The neutron lifetime has beenmeasured in two ways: 1) by counting the incident neu25 ×25 × mm 270
trons and the protons from neutronResonancebeta decay spin
(beamﬂippers
Beam On
Beam Oﬀ
5ﬂux
TPC
5.7 ×10 Spin
1/s[3]
1
method) and 2) by storing UCNs in aNeutroncontainer
andinside
deLeadFlippertermining the neutron lifetime according to the disapMagnetic
The increase of apertures of neutron
optics and the neutron ﬂux for ML
pearing time (storage method). Currently, the lifetime
Mirror
The magnetic super mirrors are separated to 3Magnetic
stages and the numbers of mirrors odetermined via the former method is 888.0 ± 2.0 s,
Mirrorand that for the latter is 878.4 ± 0.5 s, with a difference
B4C
of 9.5 s (4.6 σ) [3]. This discrepancy is called “neutron
Spin
Flipper
lifetime puzzle” and has remainedselections.
unsolved for nearly
We measured the phase-space distributionof the neutron beam
20 years. The smaller decays compared with the disapMagnetic
direct and scattered neutrons. We are now
studying to identify the sour
Mirrorpearance suggest that neutrons are lost owing to deGuide neutrons in the next beam time to reduce theand going to shield them fromcay into dark matter or collisions with dark matter. In
Coilgeneral, different methods are needed to validate theexperimental results, as utilizing the same experimental methods may lead to the same mistakes. Using the
10 4polarization beam branch at NOP/BL05, an experiment
was conducted via a different method, in which insteadof protons, electrons were measured from the neutron
10 5
beta decays. The first lifetime result was published in2020 as 898 ±10 (stat.) +15−18 (syst.) s, which is consistent
10 6
with both the beam and bottle methods [4]. Upgradeof the experiment is under way. In 2020, a spin-flip chopper (SFC), which shapes neutron beam into bunches,
10 7
0
5
10
15
20
25
30
35
40
was replaced with a larger one (Fig.1). The intensity
TOF [ms]
was increased by 3.2 times [5]. Commissioning began
in 2021, and physics run for the neutron lifetime began
Figure 1.	(Top) setup of the new SFC. (bottom) TOF spectraof neutron bunches, the blue and red lines indicate
after the SFC was tuned. So far, a statistical uncertainty
the old and new SFC, respectively [5].
achieved at 3 s, and another 100 days of beamtime brings
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MLF Annual Report 2021

This detector was developed to measure the quantized state of neutrons due to gravity and can also be
applied to submicron neutron imaging. This detector
was developed to measure the quantized state of neutrons due to gravity. By using gadolinium grating, we
proved that inclusive spatial resolution of 0.56 ± 0.8 μm(Fig. 2) [7]. In a test of emulsion-based imaging, we successfully imaged a quartz crystal at J-PARC and captured
a clear image of 30 μm gold wires in it [8].
4. Multilayer-type neutron interferometerA neutron interferometer is a device that splits the
wavefunction of a single neutron into two paths, superimposes them, and detects the potential difference
between the two paths as a phase difference. It was put
into practical use in the 1970s and it has contributed significantly to the development of quantum mechanics,

Neutron Sciencee.g., the verification of spinors and the phase shift ofmatter waves due to gravity. Thus far, neutron interferometers have been cut out of silicon ingots, which could
only use mono-energetic neutrons and were limited insize.
A multilayer-type neutron interferometer is expected to be a new device to overcome these limitations, and improve the sensitivity by using neutrons
with longer wavelength and/or making the flight pathlonger. Especially with the time-of-flight (TOF) method,
the time-dependent systematic uncertainty can be suppressed since the interference fringes are observed on
the TOF spectrum.
We have demonstrated it with pulsed neutron at
the low-divergence branch. The geometrical opticsof the Jamin interferometer was constructed using a“beam splitting etalon” [5, 6], which is a high-precision. Electron micrograph showing a cross section of a Gd grating that was manufactured by the sameprocess as that used in this experiment. The thickness of Gd in (1)ﬃcient
is not tosu prevent cold neutrons
from passing. We used the transmission image of the edge (2) for the estimation of the resolution of theshows an image of the detector taken with an optical microscope after development, inwhich the striped distribution of tracks can clearly be seen. We acquired the absorption points using
the analysis method explained in section
1. The reconstructed tracks were classiﬁed into four types:‘Track’, ‘Track+Track’, ‘Track+Dust/Fog’, and ‘Dust/Fog’ as10.
shown‘Track’in ﬁgure
means

–8–

Figure 2.	( Top) electron micrograph showing a cross sectionof a Gd grating that was manufactured by the sameprocess as that used in this experiment. (Bottom) fit
result of the distribution of neutrons around the Gd
grating edge. The blue histogram data is an excerptof the data. The red line shows the result of the leastsquares fit of error function to the data.

93Neutron Science

MLF Annual Report 2021

assembly of multilayer neutron mirrors on a quartz substrate. The anti-correlated moderations between theforward (O) beam and the deviated (H) beam on the
TOF were clearly observed (top of Fig. 3) [11]. In case apath was covered by Cd beam stopper, the oscillation
disappeared.
The beam width is 100 μm while the beam paths are
300 μm apart, so they are completely separated. Whena material is placed in one path, the phase changes dueto the refractive index of the material. Thus, we inserted
a 300 µm thick Si into a beam path and observed phaseshift of the interference fringes (bottom of Fig. 3). Thiscan be applied to precise measurement of the scattering
length of the nuclei.

References[1] K. Mishima et al., Nucl. Instruments Methods Phys.
Res. Sect. A, vol. 600, no. 1 (2009)342–345.
[2] K. Mishima, Hamon Neutron Netw. news,vol. 25,
no. 2 (2015) 156–160.
[3] R.L. Workman et al., (Particle Data Group 2022), Prog.
Theor. Exp. Phys. 2022, 083C01 (2022).
[4] K. Hirota et al., Prog. Theor. Exp. Phys. (2020) 123C02.
[5] G. Ichikawa et al., Proceedings of science, PoS(PANIC2021) 457.
[6] N. Naganawa et al., Eur. Phys. J. C 78, 11 (2018) 959.
[7] N. Muto et al., J. Instrum, 17 (2022) P07014.
[8] K. Hirota et al., J. Imaging 7 (2021) 4.
[9] M. Kitaguchi, et al., Phys, Rev. A 67, 033609 (2003).
[10] Y. Seki, et al., J. Phys. Soc. Jpn. 79, 124201 (2010).
[11] T. Fujiie et al., Annual Meeting of the JapaneseSociety of Neutron Science 2021, online.

Figure 3.	(Top) TOF spectra of the H beam (red) and the O
beam (blue). The orange and cyan lines show themwhen the other path is covered. (Bottom) The interferometer fringes with a 300 µm thick Si in a path,and without.

K. Mishima1,2 on behalf of NOP collaboration
1
Neutron Science Section, Materials and Life Science Division, J-PARC Center; 2Institute of Materials Structure Science, KEK

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Neutron Science

BL06: Commissioning Status of Village of Neutron
Resonance Spin Echo Spectrometers (VIN ROSE)
1. Introduction
BL06 consists of two types of resonance neutron
spin echo (NSE) spectrometers, which are a modulated
intensity by zero effort (MIEZE) instrument and a neutron resonance spin echo (NRSE) instrument, which are
under construction in collaboration between Kyoto
University and The High Energy Accelerator Research
Organization (KEK) since 2011.
NSE is a variety of inelastic and quasi-elastic neutron scattering methods with fine energy resolution [1].
Because the energy resolution of the energy transfer
measurement is not limited by the energy spectrum of
the incoming neutrons in the NSE technique, a moderately (10–15% FWHM) monochromatic neutron beam
can be acceptable. In addition, the intermediate scattering function can be directly derived by NSE, so thatthe method is suitable for investigating slow relaxation
dynamics in condensed matter, and high-intensity andhigh-energy-resolution NSE spectrometers have beendeveloped [2].
By using neutron resonance spin flippers (RSFs),
which enable us to replace large magnetic precession
fields with low guide fields, downsizing and adjacenceof the two spectrometers has become possible [3].
In this report, the status of the MIEZE and NRSE
spectrometers at BL06 in FY2021 is summarized.
2. Commissioning status at BL06 in FY2021
The user program has started partially with the
MIEZE spectrometer since the 2017B proposal round. At
the NRSE spectrometer, used for fine-energy resolution,
devices, such as two-dimensional ellipsoidal neutronfocusing mirrors [4], are still under commissioning.
The main scientific highlights of BL06 achieved in
FY2021 are (i) investigations of MIEZE signals from a thinmonolayer with specular reflection and (ii) studies of ellipsoidal focusing mirrors for the NRSE spectrometers,
which are described in the following sections in detail.
3.	Investigations of MIEZE signals from a thin monolayer with specular reflection
In this study, the MIEZE method is applied to observe dynamics at the surface and the interface in a thinmonolayer. It had been thought that it would be very
difficult to separate inelastic or quasielastic neutron
scattering components from specular reflection due tothe limitation of the scattering cross-section area in thereflection geometry. At MLF J-PARC, the pulsed neutron
beam is generated by accelerated short-pulse protons,
so that the wavelengths of the neutrons can be determined with very narrow wavelength distribution via
the time-of-flight (TOF) method. Moreover, the angular
distribution of the MIEZE spectrometer is significantly
better than in the conventional neutron spin echo spectrometers. In Fig. 1, the observed normalized intermediate scattering function, Sqt, from specular reflection of acarbon monolayer on a silicon substrate is shown. In theexperiment, the neutron incident angle is fixed, and thewavelength is decoded by the TOF method. As a result,
S qt is evaluated with different Q and different t, sinceQ ∝ 1/λ and t ∝ λ3 in this case. Clear reductions of Sqt canbe observed, which suggests excitation modes rather
than diffusion modes. Similar phenomena have been reported with helium atom scattering, however, the findings have not been verified by neutron scattering. We
will explore these phenomena further by making use offlexible sample environments with neutrons.
4.	Studies of ellipsoidal focusing mirrors for the
NRSE spectrometers
This ellipsoidal neutron-focusing supermirror is essential for high-resolution NRSE spectrometers, which
can correct the optical path difference. We have developed and tested 900 mm long ellipsoidal focusing m = 5
supermirrors with 2.5 m focal length. In FY2021, the mirrors were tested at the NRSE beam line with the MIEZE
condition to investigate the possibility of focusing TOFMIEZE method. We successfully identified time-of-flight
MIEZE (TOF-MIEZE) signals for neutrons elastically scattered at the sample under a focused geometry using thesupermirrors. The effective frequency of the TOF-MIEZE
signal was 108 kHz. The Fourier time range was coveredfrom 0.48 to 5.3 ns using the TOF method with neutron
wavelengths from 0.65 to 1.45 nm. The result has beensummarized in ref. [5].
5. Summary
In this report, the activities of BL06 VIN ROSE in
FY2021 were summarized. The two achievements wereintroduced, i.e., the investigations of MIEZE signals froma thin monolayer with specular reflection, which is currently only possible with J-PARC, and studies of ellipsoi95

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MLF Annual Report 2021

Figure 1.	Tentative results of the normalized intermediate scattering function and related
data obtained by 100 kHz MIEZE signals from neutron specular reflection in a carbon monolayer on a silicon substrate. The left-hand ordinate represents the visibility of the MIEZE signals, and the right-hand ordinate displays reflectivity.

dal focusing mirrors for the NRSE spectrometers, which
is a necessary step to advance the development of the
NRSE spectrometer.

References[1] F. Mezei ed., Neutron Spin Echo, Lecture Notes inPhysics, (Springer, Berlin) 128, (1982).
[2] B. Farago et al., Neutron News 26, (2015) 15.
[3] M. Hino et al., Physics Procedia 136-141, (2013) 136.
[4] T. Hosobata, M. Hino, H. Yoshinaga, T. Kawai, H. Endo,
Y. Yamagata, N. L. Yamada, S. Takeda, JPS Conf. Proc.
22, (2018) 011010.
[5] F. Funama et al., JPS Conf. Proc. 33, (2021) 011088.

H. Endo1,2, M. Hino3, T. Oda4, N. L. Yamada5, H. Seto1,2, and Y. Kawabata3
Neutron Science Division, Institute of Materials Structure Science, KEK; 2Neutron Science Section, Materials and Life Science Division,
J-PARC Center; 3Institute for Integrated Radiation and Nuclear Science, Kyoto University; 4The Institute for Solid State Physics, The Universityof Tokyo; 5Center for Integrative Quantum Beam Science, Institute of Materials Structure Science, KEK

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Neutron Science

BL08: Verification of Sample Temperatures Using a
High-Temperature Sample Stick for Cryofurnace
1. Introduction
In FY2021, the cryofurnace was installed in
BL08 Super High Resolution Powder Diffractometer,
SuperHRPD [1, 2]. The commissioning test was reported
in the MLF Annual Report 2020 [3]. This cryofurnace
can be used with a low-temperature sample stick formeasurements in the 4 K–300 K range and a hightemperature sample stick for the 300 K–800 K range.
In measurements below 300 K, the introduction of exchange gas into the sample chamber controls its atmosphere, so that sample temperature irregularities are nota cause for concern. The high-temperature sample stickhas double radiation shielding around the sample. The
exchange gas in the sample chamber must be evacuated to create a vacuum, partly to protect the cold head,
and the sample temperature is controlled by a heater
attached to the top of the sample holder. However, sincetemperature is controlled by heat conduction throughthe sample holder, the temperature irregularities are an
issue due to the vertical length of the sample holder.
Therefore, the sample temperature was verified using
the structural phase transition of barium titanate, BaTiO3.
2. Temperature verification experiment
As a powder sample, BaTiO 3 manufactured by
Sigma-Aldrich Co. LLC with a particle size < 2.0 μm
and a purity of 99.5% was used, and the sample holder
was a standard 6 mm diameter vanadium-nickel alloy
holder. Neutron powder diffraction measurements were
performed in the temperature range of 273 K–285 K and
388 K–403 K to take advantage of the structural phasetransition of BaTiO3 above room temperature (Fig. 1 [4]).
Temperature changes were performed by an increase
path, and the sample space was under vacuum condition with a high-temperature sample stick. The accelerator power at the time of measurement wasapproximately 700 kW, and sufficient statistical data tocompare peak profiles could be obtained in 30 minutes
per measurement.
3. Discussion
The temperature dependence of the diffraction peaks
around 280 K and 400 K are plotted in Fig. 2. (a) and (b)show a marked change in peak shape indicating a structural phase transition around 280 K. This is considered
to indicate the phase transition from the orthorhombic
phase to the tetragonal phase shown in Fig. 1. Similarly,in (c) and (d), a change in the peak shape indicating aphase transition to the cubic phase is seen around 400 K.
The transition temperatures evaluated from the dielectric constants were ~280 K and ~400 K, respectively, it
can be assumed that the sample temperature approximately reflects the temperature of the stick sensor.
Although the statistics were somewhat insufficient,a crystal structure refinement by Rietveld analysis was
performed. The software Z-Rietveld (Ver. 1.1.11) [5, 6]
was used for the analysis. The analytical profile near thetransition temperature is shown in Fig. 3. At 285.6 K, theanalysis with the coexistence of two phases, orthorhombic and tetragonal, showed good profile agreement. The
analysis was also performed around 400 K, and a trendof coexistence of tetragonal and cubic crystals was

Figure 1.	Change of dielectric permittivity of the BaTiO3 single crystal with temperature. The schematics of Ti-displacement in the oxygen octahedronof the perovskite structure are also shown.

97

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MLF Annual Report 2021

Figure 2.	(a), (b) Temperature variation of the diffraction peak near 280 K. (c), (d) Temperature
variation of the diffraction peak near 400 K. The displayed temperature is the value ofthe platinum resistance temperature sensor PT100 installed on the sample stick.

Figure 3.	The Rietveld analysis results at 285.6 K. In this analysis, we obtained the resultthat the orthorhombic phase and tetragonal phase were mixed at a mass ratio
of about 6:4.

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MLF Annual Report 2021

10(a) 398.0 K

10(b) 401.0 K

8

8

6

6

6

4

2

0

1.990

Intensity / arb.unit

8

Intensity / arb.unit

Intensity / arb.unit

10

4

2

0

2.000

2.010
d/Å

2.020

1.990

(c) 403.9 K

ycal
yint
delta
Tetragonal
Cubic

4

2

0

2.000

2.010
d/Å

2.020

1.990

2.000

2.010
d/Å

2.020

Figure 4.	The Rietveld analysis results near the transition temperature 400 K. In those temperatures, a better
fit was obtained by analyzing the coexistence of two phases, tetragonal and cubic.

observed at 398.0 K, 401.0 K, and 403.9 K (Fig. 4). In thisseries of measurements, it was not possible to determine whether the coexistence of these two phases wasa characteristic of the sample during the phase transition process or due to temperature irregularities. In the
future, it will be necessary to evaluate whether the coexistence is due to temperature irregularities or not byusing an incident beam slit to check the differences in
the profiles of the sample in the vertical direction.
4. Summary
The accuracy of the sample temperature above
room temperature for cryofurnace was investigated using a high-temperature sample stick. The sample temperature assumed from the profile changes was foundto follow the temperature of the sensor attached to the
top of the sample holder. However, to evaluate the temperature irregularity of the sample itself, measurement

using a slit is necessary, and we would like to conduct
this in a future commissioning, including Rietveld analysis with data with higher statistics.
References[1] S. Torii, M. Yonemura, T. Y. S. Panca Putra, et al., J.
Phys. Soc. Jpn., SB020 SB020-1-4 (2011).
[2] S. Torii, M. Yonemura, Y. Ishikawa, et al., J. Phys.: Conf.
Ser., 502 012052 (2014).
[3] S. Torii, M. Hagihala, K. Cho, et al., MLF Annual Report
2020, 94–95 (2021).
[4] A. P. Barranco, Ferroelectric Materials – Synthesis
and Characterization, IntechOpen (2015)[5] R. Oishi, M. Yonemura, Y. Nishimaki, et al., Nuclear
Instruments and Methods, A600 94–96 (2009).
[6] R. Oishi-Tomiyasu, M. Yonemura, T. Morishima, et al.,J. Appl. Cryst., 45 299–308 (2012).

S. Torii1,2, S. Yamauchi1,2, and K. Mori1,2
1
Neutron Science Section, Materials and Life Science Division, J-PARC Center; 2Institute of Materials Structure Science, KEK

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MLF Annual Report 2021

BL10: NOBORU
1. Introduction
In FY 2021, twenty-one general-use proposals andtwo project-use proposals were carried out at NOBORU.
Two long-term proposals were postponed due to theentry restriction for foreigners because of the COVID-19
pandemic. This year, in addition to the fixed-point observations that have been conducted every year, we started
testing 90° diffraction experiments using a 1 mm radialcollimator on long-term loan from BL19 (TAKUMI). Using
this collimator, we plan to aim at mapping heterogeneous cultural heritage samples by neutron diffraction
in a gauge volume of about 1 mm × 1 mm × 4 mm at
NOBORU.
2. Experimental setup
Although NOBORU does not use a neutron guidetube, we can use neutrons of sufficient intensity over awide wavelength band, since the standard sample position is 14 m from the moderator. The diffraction detector
consists of 16 3He PSD tubes (Toshiba E6867-600) withdimensions of 60 cm length and 1/2-inch in diameterand nominal 10 MPa of gas pressure. The detector box
is placed near the inner wall of the experiment room
to obtain a flight path of approximately L2 = 1.4 m. The
incident beam path to 50 mm in front of the sample in

the experiment room consists of NW50 flanged vacuum tubes covered with B4C rubber sheet. At the endof the tube, i.e., at the location of the vacuum window,
a 5 mm wide × 12 mm high aperture was temporarily
made with B4C rubber (this is considerably larger than
the final aperture size we are aiming for). The 1 mm radial collimator was placed on the experiment table using acommon laser marking. Powder samples were enclosed
in a standard vanadium (V) holder (Taiyo Koko PV-06-F)
with a 6 mm outside diameter and 0.1 mm wall thickness. In order to examine the capability to detect minor
phases, we also used bulk steel (Fe-0.18C) previously
measured by TAKUMI to see if the peaks of cementite(Fe3C) were clearly visible.
3. Results
After starting the on-beam test, x and z scans were
performed to center the sample using silicon (Si) sealed
in a standard V holder with additional shielding materials as shown in Fig. 1. An example result of the z scan isshown in Fig. 2. Neutron counts in the range avoiding
the Bragg peaks at 12.3 to 16.6 ms (hatched range in
Fig. 2a) are integrated and are plotted as a green circle
in Fig. 2b. The curve fitting allowed us to determine thatz was centered at about −0.7 mm in this experimental

Figure 1.	Experimental setup for the 90° diffraction experiment at NOBORU.

100

MLF Annual Report 2021

setup. The gauge volume width expected by the radialcollimator is expressed in Fig. 2 as a horizontal grid, andthe cut view of the φ6 mm sample holder is also inserted
in this figure as a circle, with a 5 mm wide neutron beam
path overlapping it. It can be seen that the volume ofthe holder in contact with the neutrons contrasts wellwith the background counts due to incoherent scattering from V.

Neutron Science

Figures 3a and 3b show the diffraction patterns of bulk
steel for each PSD without and with time-focus correction,
respectively. The area circled in blue square appears tohave peaks that were not detected, except for this bulk
steel. These peaks were not included in TAKUMI’s measurement data, but were comparable to the peak intensityof Fe3C in these data. Further verification of this is needed.

Figure 2.	Diffraction patterns of Si sealed in a standard V holder. Z-position was moved in 1 mm intervals.

Figure 3.	Diffraction patterns of bulk steel for each PSD without time-focus correction (a) and with time-focus correction (b).

K. Oikawa and Y. Tsuchkawa
Neutron Science Section, Materials and Life Science Division, J-PARC Center101Neutron Science

MLF Annual Report 2021

Recent Developments at BL11 PLANET
1. Introduction
This year, the following devices and software were
installed:i) Automatic sample changer and its remote-control
systemii) Radial collimators with a field of view of 0.8 mmiii) Automatic sample positioning command for the experiments using PE pressesiv) Software to mask unwanted Diamond Bragg spots
in the data taken with anvils or sample containers
made of single crystal diamonds
The details are shown below.
2.	Automatic sample changer and its remote-control
systemAt PLANET, ambient-pressure data are collected byplacing a sample in a vanadium can (Taiyo Koko Co. Ltd)on the six-axis press. So far, when several samples were
measured successively each one had to be replaced byhand. Since the typical exposure time for one measurement is about 3 to 6 hours, the continuous measurements of several samples late at night have exhausted
the beamline staffs. The automatic sample changer has
been developed to improve this situation (Fig. 1). It consists of a motorized stage and a frame for attaching cans.
Five cans can be attached to the frame at maximum
and each can is remotely positioned at the center of the
six-axis press in the precision of 0.1 mm by shifting the

Figure 1.	Photo of the automatic sample changer mounted
on a six-axis press.

102

frame. By using a stage control command newly added
to Experimental Scheduler (device control and data acquisition software), a series of sample data acquisitionis possible by making the batch sequence.
3. Radial collimators with a field of view of 0.8 mm
With the increase in the beam power at the MLF, theuse of a smaller sample and resulting experiments at ahigher pressure became possible. Related to this, the necessity for reducing the diffraction gauge volume is increasing. This year, radial collimators with a field of viewof 0.8 mm along the incident beam direction are developed for the experiments using Paris-Edinburgh (PE)presses or diamond anvil cells. Figure 2 shows the efficacy of the collimators. The intensities of the Diamond
Bragg peaks are significantly reduced while maintaining
sample intensity, which enables more precise structure
analysis at higher pressures.
4.	Automatic sample positioning command for PE
presses
Since the pandemic of COVID-19, many proxy experiments have been conducted at PLANET. Currently,
almost all high-pressure devices can be controlled via
Experimental Scheduler at PLANET; thus, a proxy experiment is not difficult to conduct. Among them, thePE press is the most frequently used device because of
its easy sampling and high reproducibility in pressure

Figure 2.	Comparison of data of ice VII compressed with ananopolycrystalline diamond anvil cell using radialcollimators with a field of view of 1.5 mm (black)and 0.8 mm (red). “ i ” and “ d ” denote Bragg peaks
from ice VII and diamond anvils, respectively (courtesy of Dr. Komatsu).

MLF Annual Report 2021

generation. However, fully automatic experiments werestill difficult to conduct because the sample drifts fromthe diffraction gauge volume during compression andthe sample position must be readjusted after each compression. To achieve it, the automatic sample positioning
command is implemented in Experimental Scheduler. It
consists of three basic processes: i) scan the sample position along x, y, z or θ axis, ii) fit the obtained scan profiles
by a Gaussian function and find the optimum position,and iii) move the sample to the optimum position. By using this command, all data collection at high pressures
is completed once the target loads, scanning axis/range
and data acquisition condition are input in Experimental
Scheduler as a list.
5.	Software to mask unwanted Diamond Bragg spots
in the data taken with anvils or sample containers
made of single crystal diamonds
With the increase in beam power, structure analysesof crystalline samples using diamond anvil cells or liquidsamples using single-crystal diamond sample containers became realistic. Previous feasibility tests, however,demonstrated strong contamination of Bragg spots
from single-crystal diamonds. The source of the scattering is spatially too close to the sample to eliminate themwith radial collimators; thus, we tried to mask the Bragg
spots in data reduction.

Neutron Science

Figure 3 shows an example of data taken with a diamond anvil cell. In the detector map, Laue patterns of
diamonds are clearly observed. Thus, we took a measure
to remove them by estimating all the expected positions
from the refined UB matrixes of diamond crystals.
The software has the following functions:i) Pick up spot’s positions in the selected area (and TOF
region) and store them in the list.
ii) Find (and refine) UB matrixes from the positions in
the list.
iii) Calculate all the expected positions on the basis of
the refined UB matrixes and store the regions to bemasked in a mask file.
In addition to the diamond Bragg spots, it is known
that the incident beam impinged on the sample partly
loses its intensity at specific wavelengths due to theBragg reflection of a diamond in front of the sample (theso-called “Diamond Dips”). This also causes a systematic
reduction in scattering intensities from the sample atthe corresponding wavelengths. Thus, the software also
has the following function:iv) Calculate the expected TOF regions of “Diamond Dip”
and store them in the mask file.
By using a mask file made by this software, moreaccurate scattering intensity of the sample is obtainable.

Figure 3.	Newly developed software for removing the effects of single crystal diamonds.

T. Hattori1, A. Sano-Furukawa1, S. Machida2, J. Abe2, K. Funakoshi2, and N. Okazaki2
Neutron Science Section, Materials and Life Science Division, J-PARC Center; 2Neutron Science and Technology Center, CROSS

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High Resolution Chopper Spectrometer HRC
1. Introduction
The High Resolution Chopper Spectrometer (HRC) is
being operated at BL12 in MLF under the S-type projectof IMSS, KEK and the IRT project of ISSP, the Universityof Tokyo, in order to study dynamics in condensed matter, especially in a wide range of correlated electron
systems. The activities of the HRC in FY2021 are summarized in this report.
2. Instrumentations
The 1 K refrigerator on HRC is a 3He gas circulation
type one, where the lowest temperature was 0.6 K in thebest case. Recently, the lowest temperature destabilized
and became 2 K, the volume of the 3He gas decreased.
We cleaned the circulation system of the 3He gas andadded more 3He gas, but the situation did not improve.
For this reason, we decided not to use it for the generaluser program. An investigation of the cause revealed ananomalous gas flow rate in the heat exchanger in thecold head caused by a leak in the 3He exhaust line. The
heat exchanger was remanufactured and replaced andcooling down to 0.6 K was confirmed.
Since it was decided not to use the 1 K refrigerator for experiments during the repair period, instead,
Heliox (3He gas sorption type refrigerator with minimum
achievable temperature 0.3 K), which had been stored
for a long time, was started up and commissioned to conduct low temperature experiments on the S-type project.
Information on 3He gas sorption type refrigerators
was collected and reviewed by cryogenic engineers andinstrument staffs of HRC and POLANO, and specifications were developed for a higher performance refrigerator than Heliox. We plan to place a manufacture orderfor it next fiscal year.
The 4 K GM (Gifford-McMahon) refrigerator isthe most frequently used refrigerator in experiments
on HRC and has been in operation for more than
24,000 hours in total, and has exceeded 10,000 hours
since the last maintenance, so scheduled maintenance
was performed.
A cryofurnace (T = 4 - 800 K) was manufactured anddelivered (Fig. 1), and the experiment control program
YUI was modified to accommodate it. We plan to perform the commissioning next fiscal year.
As reported last year, T0#2 (the second machine of
the T0 chopper) is currently running and T0#1 is stored.
We performed maintenance work for T0#1.
In January 2019, the Fermi chopper became out
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of control because of a touch-down in the magnetic
levitation system of the rotor. This Fermi chopper was
replaced by a spare one. Last year, to repair the Fermi
chopper, the damaged touch-down bearing was replaced by a new one. However, this did not restore thestable rotation because of a loss of the balance of therotor. This year, further work was performed to improvethe balance, and the repair was completed.
The wave shape of the 25 Hz timing signal input
to the Fermi chopper is disturbed by noise from the T0
chopper control system, causing a problem that disrupts the control of the Fermi chopper and needs to beaddressed.
The circuit of the T0 chopper control board wasdeveloped by a KEK engineer in the past, and some
information has not been made public. In advancing
maintenance, the control algorithm was investigated.
In the development of the Fermi chopper, a feasibility of gadolinium as a shielding plate for the slit package was examined. Material strengths were measured,and gadolinium film formation tests were conducted forthe thickness of gadolinium of 0.02 mm and 0.5 mm onaluminum. It has been confirmed that it was possible
to deposit 0.02 mm and 0.5 mm of gadolinium layer onboth sides of aluminum foil and thin sheet.

Figure 1.	Cryofurnace delivered to HRC in March 2022.

MLF Annual Report 2021

A scheduled maintenance of the cryopump in
the vacuum scattering chamber and an overhaul of
the turbomolecular pump in the Fermi chopper were
performed.
The computational environment has been developed and maintained by ISSP, but from this fiscal year,
a KENS engineer will maintain the parts related to DAQ
MW common to KENS. ISSP will continue to be in chargeof the part related to YUI and HANA.
The servers related to DAQ MW and storage will
be migrated to virtual servers according to the plan in
KENS. The servers related to YUI and HANA will also be
migrated to virtual servers, but it will be necessary tocope with the termination of the support of the operating system and the version up of python in the future.
3. Scientific results
Complex magnetic phase diagram in the non-centrosymmetric compound CePtSi3 was determined withmagnetization measurements [1]. We plan to perform
experiments on HRC using a single crystal sample toelucidate magnetic fluctuations unique to this system

Neutron Science

under the influence of antisymmetric spin-orbit interaction. Crystalline electric field level scheme in the noncentrosymmetric CeRhSi3 and CeIrSi3 was determined,
an emergence mechanism of superconductivity was
discussed in relation to the wavefunction of the groundstate of f-electrons in crystalline electric field [2,3]. Spingap was observed in sodium superoxide NaO2, whereO2- is a magnetic ion, it was found that this system shows
the spin-Peierls transition [4]. Antiferromagnetic Kitaev
interaction in Na2Co2TeO6 was investigated [5, 6]. Using
the results of one experiment (2019B0350), the twogroups wrote their own papers.
References[1] D. Ueta et al., J. Phys. Soc. Jpn. 90 (2021) 064712.
[2] D. Ueta et al., J. Phys. Soc. Jpn. 90 (2021) 104706.
[3] D. Ueta et al., MLF Annual Report 2021 (this issue).
[4] M. Miyajima et al., Phys. Rev. B 104, L140402 (2021).
[5] G. Lin et al., Nat. Commun. 12, 5559 (2021).
[6] C. Kim et al., J. Phys.: Condens. Matter 34, 045802(2022).

S. Itoh1,2, T. Masuda3,2, T. Yokoo1,2, T. Nakajima3, S. Asai3, H. Saito3, D. Ueta1,2, D. Kawana3, R. Sugiura3, T. Asami3, T. Seya1,2,
S. Yamauchi1,2, S. Torii1,2, Y. Ihata4, and H. Tanino1,2
1
Neutron Science Section, Materials and Life Science Division, J-PARC Center; 2Institute of Materials Structure Science, KEK; 3The Institutefor Solid State Physics, The University of Tokyo; 4Technology Development Section, Materials and Life Science Division, J-PARC Center

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BL14 AMATERAS
1. Introduction
AMATERAS is a cold-neutron disk-chopper spectrometer for studies on dynamical properties of atomic,
molecular and magnetic systems from cold to sub-thermal energy range with high efficiency and flexible resolution [1, 2]. Due to the world pandemic since 2020,
the instrument group carried out remote experiments
for foreign users in JFY2021. We hosted graduate students for a short period as Fellows of Advanced Scienceand Internship of JAEA. Furthermore, in order to reduce
staff workload and to relax the excessive competition for
beamtime, we have upgraded some components of the
instrument in recent years.
2. User program, outreach activities and outcomes
The number of general proposals (short-term)
submitted to the 2020B+2021A and 2021B periods
were 35 (accepted: 7, reserved: 27, not approved: 1)
and 47 (accepted: 7, reserved: 35, not approved: 5), respectively. Consequently, eight experiments from the
2020B+2021A proposals and nine experiments fromthe 2021B proposals, including some “reserved” ones,
were carried out in JFY2021. Japanese users carried out
their experiments on-site, while foreign users were not
yet able to visit the facility because of travel restrictions
due to the Covid-19 pandemic since 2020. Thus, the instrument group members carried out these six experiments remotely. In addition to the general (short-term)
proposals, one general (long-term) proposal and threeproject research proposals were also carried out. As a recent trend in the research field, the number of proposals
on magnetism and strongly correlated electron systems
is continuously increasing. Actually, only one proposal

approved in the 2021B term is for the energy materials
and the 16 other proposals are related to magnetismand strongly correlated electron systems.
In this fiscal year, 13 refereed papers related toscientific research at AMATERAS and one proceedings
paper on instrumentation were published. AMATERAS
hosted some students this fiscal year: Mr. Ryo Murasaki,
a doctoral student from Tohoku University, and Ms.
Rika Inoue, a master course student from Ochanomizu
University, as Fellow of Advanced Science and Mr. Pharit
Piyawongwatthana, a doctoral student from Tohoku
University, based on Internship of JAEA.
3. Instrument-related upgrades
Recently, we have upgraded some components toincrease the efficiency of experiments. Following the
upgrade of the controlling system on the vacuum scattering chamber in 2020, we extended the neutron guidetube by ~50 cm at a section between the monochromating chopper and the window of the vacuum scattering chamber (Fig. 1) in JFY2021. It is expected that theneutron intensity, especially for the low-energy region,
increases by extending guide mirrors to this section
and further downstream. We removed a B4C collimator,
which has been placed between the monochromating
chopper and the vacuum scattering chamber (Fig. 2(a)),
and then installed a guide jacket made of stainless steel
and a guide mirror (Fig. 2(b)). Its alignment was done
after the installation (Figs. 2(c) and 2(d)). This extension
increased neutron intensity by more than 20% at thelow energy region, as shown in Fig. 3. We will compare
the intensity to the simulation result.

Figure 1. Beam transport of AMATERAS.

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Figure 3.	
Beam intensity as a function of the incident neutron energy and its comparison of before and after the extension of the guide mirror.

Figure 2.	Installation of an additional guide tube. (a) B4C
collimator that has been placed before. (b) Newly
installed guide tube. (c) Alignment of the guidemirror. (d) New guide tube and jacket viewed fromdownstream.

4. Future plans
We will continue with the further upgrades and automation of components, which are important to savetime to change the experimental configuration and to
reduce our workload. We have purchased a new cryogen-free top-loading cryofurnace in JFY2021. We willcommission this equipment next year, aiming to install

it for users’ experiments. We also plan to fully automate
the pumping system of the vacuum scattering chamber.
References[1] K. Nakajima et al., J. Phys. Soc. Jpn. 80 SB028 (2011).
[2] K. Nakajima, RADIOISOTOPES 66 101 (2017).

S. Ohira-Kawamura1, M. Kofu1, N. Murai1, Y. Inamura1, D. Wakai2, and K. Nakajima3
Neutron Science Section, Materials and Life Science Division, J-PARC Center; 2NAT Corporation; 3Material Science Research Center

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Upgrading TAIKAN
1. Introduction
The small and wide angle neutron scattering instrument TAIKAN (BL15) has been developed and upgradedat J-PARC to analyze precisely and efficiently the microstructures or hierarchical structures of substances invarious scientific fields with a 1-MW spallation neutron
source [1]. In FY2020, it was upgraded further to perform long-term stable measurement, humidity control
measurement, and sample exchange measurement.
2. Upgrading for long-term stable measurement
The detector system of TAIKAN is composed of
5 detector banks: small-, middle-, high-, ultra-small-angle, and backward detector banks. The number of 3He
tubes is 912, 720, 400, and 80 for the small-, middle-,
high-angle, and backward detector banks, respectively,
or 2,112 in total. The installation ratios of the 3He tubes
are 100, 100, 76, and 100% for the small-, middle-, highangle, and backward detector banks, respectively, andthe overall average is 94%.
The gas pressure of these detectors is basically
6 atm, but 32 detectors in the center of the small-angle
detector bank and 80 detectors in the backward detector bank were replaced in FY2019 with 20 atm gas pressure detectors for high efficiency measurements.
However, radiation damage was observed in the detectors of the small-angle detector bank, so the additivegas for the 64 detectors in the central part was replaced
from CF4 to N2 to extend their service life.
3.	Upgrading for humidity control measurement
and sample exchange measurement
A humidity control system was developed (Fig. 1).
The system is capable of controlling dew point with anaccuracy of ±0.2°C for dew points ranging from -15 to
81°C. The flow rate is 0.05 ~ 3 L/min. The accuracy in gas
mixing is within ±1 %. The pressure is 1 atm. The system
can achieve automatic and quick humidity changes andcontinuous H2O-D2O composition changes because it
has a two-temperature method humidity generator. Twotypes of sample cells are available for the system. They
are a single-sample cell and a multiple-sample cell. The
former cell is designed for temperature and humidity
stability and fast changes in humidity. The latter cell isdesigned for automatic exchange of seven samples.

A sample exchanger with Peltier cooling elements
was also developed (Fig. 2). The sample exchanger canbe installed in three units of nine samples, each of which
can be independently temperature-controlled in therange of 20 ~ 80°C.
4. Future prospects
The installation of long-life detectors will lead to stable instrument operation. In addition, the developmentof the humidity control system and the Peltier-type sample exchanger will be effective for the measurement offuel cell materials, soft matter, and biomatter, and is expected to further promote uses in these research fields.

Figure 1.	A humidity control system: (left) humidity generator, (upper right) single-sample cell, (lower right)
multiple-sample cell.

Figure 2. A Peltier-type sample exchanger.

Reference[1] S. Takata, J. Suzuki, T. Shinohara, T. Oku, T. Tominaga,
K. Ohishi, H. Iwase, T. Nakatani, Y. Inamura, T. Ito, K.
Suzuya, K. Aizawa, M. Arai, T. Otomo and M. Sugiyama,
JPS Conf. Proc., 8 036020 (2015).

J. Suzuki1, S. Takata2, K. Ohishi1, H. Iwase1, Y. Kawamura1, K. Hiroi2, T. Morikawa1, and M. Ueda1
Neutron Science and Technology Center, CROSS; 2Neutron Science Section, Materials and Life Science Division, J-PARC Center

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Renewal of Optical Components for Multi Incident-angle
Neutron Reflectometry
1. Introduction
Neutron reflectometry (NR) is very useful for investigations of structures of surfaces and buried interfaces
composed of soft materials. SOFIA is a horizontal-type
neutron reflectometer constructed at Beamline 16 (BL16)of the Materials and Life Science Experimental Facility(MLF) of the Japan Proton Accelerator Research Complex(J-PARC) [1, 2]. Due to the high-flux beam of J-PARC, lessthan one hour is needed for taking a full Q-range data andonly a few seconds for a limited Q-range data in the case ofa sample with 3 inches (76 mm) in diameter; even though
the beam power is still one-third of the planned value, 1
MW. However, several hours are still needed for a small
sample, such as 10 mm × 10 mm, which is a typical size ofa sample for X-ray reflectometry.
For the further upgrade of the SOFIA reflectometer, wehave developed an elliptical focusing mirror to illuminate asample with a neutron beam with a large beam divergence.
So far, we have developed focusing super-mirrors [3–5].
The latest mirror is capable of focusing neutrons with awidth of 0.13 mm in full width at half maximum (FWHM).
This mirror has already been installed in the SOFIA andopened for users as reported last year.

Furthermore, we have a plan to realize a multi-incident
neutron reflectometry (MI-NR) at the SOFIA by applying focusing mirrors, in which neutrons are transported by two
different paths and converged at a sample position withdifferent incident angles (Fig. 1). This method enables us
to measure a Q-region from the total reflection at low-Q to
the measurable high-Q limit of a typical sample at a time
without any angle scan required for a conventional NR experiment [6]. To accept the neutron beams with two different paths by two detectors independently, we installed
last year a compact detector utilizing a flat-panel multianode-type photomultiplier tube (FRP) with the detection
area of 48 × 48 mm2 [7, 8]. This year, we installed opticalcomponents for MI-NR: two disk choppers to change therepetition rate of neutron pulses of each neutron path independently; a rough focusing guide to transport neutron
images at the chopper positions to the positions of virtual
sources for fine focusing as follows.
2. Disk choppers
So far, the SOFIA employed double frame modewith a chopper rotation speed of 12.5 Hz (half of theneutron pulses generated at the source) to extend the

Figure 1. Design of optics for realizing MI-NR at the SOFIA. This year, disk choppers and a focusing guide were installed.

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Figure 2.	Double chopper system for MI-NR. The upper half and lower half of the beam at the guide exit are independently chopped
by the upper and lower choppers, respectively.

Q-range by using a wider wavelength band. This enables
us to perform time-slicing measurements with wider
Q-region without any incident-angle scan. However,the Q-region is still limited even with the double frame
mode due to the limitation of the wavelength band,and the neutron flux is reduced by a half because every
other neutron pulse is cut by the chopper. With taking
the merit and demerit of the double frame mode mentioned above, the MI-NR at the SOFIA reflectometer isgoing to be realized by the combination of the higher
flux beam at 25 Hz for higher incident-angle and wider
wavelength band beam at 12.5 Hz for lower incidentangle. It should be noted here that the longer exposure
time is required for the measurement at higher incidentangle because of lower reflectivity. Therefore, the reduction of the flux due to the double frame mode at thelower incident-angle has no effect on the total measurement time because it is limited by the statistic at thehigher incident-angle.
To realize the combination of the two beams above,
two disk choppers were installed at the exit of the guidetube as shown in the Fig. 2. The choppers were made ofcircular aluminum plates with thickness of 4 mm, andGd2O3 was painted on them to stop neutrons by the
choppers. As two beams with different tilt angle, 2.22°
and 5.71°, are acceptable at the SOFIA, the choppers
110

have two windows: one is at the edge to realize the MINR at the 2.22° beam, and the other at the middle ofthe disk to cut the beam with the tilt angle of 5.71° toilluminate free-liquid surface with high incident-angle.
3. Focusing guide tube
As mentioned above, the upper and lower half partsof the 2.22° beam are separately cut by the two disk
choppers, in which the repetition rate can be controlled
to be 25 or 12.5 Hz independently. The focusing guideis to transport the two beams at the chopper position
to the virtual sources 4500 mm from the choppers: one
is for a lower incident angle and the other is for a higher
one. As mentioned before, a shorter exposure time isgenerally required for a lower angle. Therefore, the repetition rate for the lower angle can be reduced to extend
the measurable Q-region down to the total reflection
region in exchange for less flux.
For this purpose, a focusing guide was installedat the middle of the choppers and virtual sources. The
guide is 1300 mm in length and equips 3Qc supermirrors inside, in which the shapes of the top and bottom
sizes are ellipses with foci at the upper and lower halfof the beam at the chopper position and lower and upper exit at the virtual sources, respectively. Note herethat a separator was placed to avoid the cross talk of theMLF Annual Report 2021

Neutron Science

Figure 3.	Focusing guide for MI-NR. Top and bottom mirrors of the guide focus the images of 1st virtual sources at the chopper tothe 2nd virtual sources at the positions of slits.

two beams after the chopper, in which an iron plate wasplaced at the center to cut fast neutrons and two 2.5Qc
supermirrors on glasses were positioned on the top andbottom sides of the iron plate to guide neutrons.

count the neutrons reflected on the sample separately.
After these planned upgrades are installedcompleted
next year, hopefully, the first MI-NR measurement will
be demonstrated.

4. Future plans
The disk choppers and focusing guide installed inthis year can transport neutron beams having different repetition rate at the virtual sources position. Next
year, a slit system with two apertures to make virtual
sources with the optimized gaps depending on the incident angle and sample size is going to be installed. In
addition, a set of precise focusing mirrors to transport
neutrons from the virtual sources to a sample position
with different incident angles is also to be installed. A
set of FRP detectors developed last year is to be used toReferences[1] N. L. Yamada et. al., Euro. Phys. J. Plus, 44 (2011) 9424.
[2] K. Mitamura et. al., Polymer J., 45 (2013) 100.
[3] S. Takeda et. al., Opt. Express, 24 (2016) 12478–12488.
[4] T. Hosobata et. al., Opt. Express, 25 (2017) 20012–20024.
[5] T. Hosobata et. al., Opt. Express, 27 (2019) 26807–26820.
[6] N. L. Yamada et. al., J. Appl. Crystallogr., 53 (2020)
1462–1470.
[7] S. Satoh, Plasma Fusion Res. 13 (2018) 3–6.
[8] F. Nemoto et. al., Nucl. Instrum. Methods Phys. Res. Sect.
A, 1040 (2022) 166988.

N. L. Yamada1,2, T. Hosobata3, and M. Hino4
1
Neutron Science Section, Materials and Life Science Division, J-PARC Center; 2Institute of Materials Structure Science, KEK; 3RIKEN Center
for Advanced Photonics, RIKEN; 4Institute for Integrated Radiation and Nuclear Science, Kyoto University

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Current Status of SHARAKU: Polarized Neutron
Reflectometer
1. Introduction
SHARAKU is a neutron reflectometer (NR) installed
at BL17 in the Materials and Life Science Facility (MLF)
of J-PARC to investigate the nanometric structure ofsurface and interfaces in a sample with spin-polarized
neutrons. It has been employed for the structure analysis of thin films in various research fields, such as soft
matters and magnetism. In this fiscal year, we developed
a Helmholtz coil to allow the polarized neutron reflectometry (PNR) measurement in a weak magnetic field
and a deep learning technique to accelerate the dataacquisition in the experiment.
2. PNR in weak magnetic fieldPNR is a non-destructive method for characterizing
interface and surface structures in magnetic thin films.
From the start-up period to the present, SHARAKU has
been used to measure PNR data of various magnetic
thin films under a strong magnetic field environment,i.e., from 5 mT to 6.5 T, and many results have been produced. On the other hand, the need for magnetic structure research under weak magnetic field conditions has
been increasing in recent years, especially in spintronics
device research, and a weak magnetic field environment
near 2 mT is indispensable. For example, 90° interlayer
coupling pseudo-antiferromagnetic films have been actively studied as high-speed, energy-saving magnetic
recording media and high-sensitivity sensors in the GHz
region. Such devices work by generating magnetic wall
movement, magnetic reversal, and magnetic rotation ina weak magnetic field, which is the operating magnetic
field. However, the magnetic domain, which is the heartof the device, is difficult to observe with non-neutronprobes due to its complex stacking structure [1]. When
conducting weak-field experiments, the conventionallyused electro-magnet (1 T or lower) in BL17 contains aniron core as a pole piece, and because of its history, themagnetic field uniformity cannot be maintained in the
weak-field region and a residual magnetic field exists,making it difficult to use the magnet as either a sample
field or a polarized neutron field. In response to this necessity, a weak-field sample environment was fabricatedand commissioned. This report introduces the apparatus
and describes the polarization performance.
Figure 1 shows a schematic figure of the weak-fieldsample environment. The magnetic field in the sample
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position is generated by Helmholtz coils (HC), which
generate magnetic field lines perpendicular to the direction of incoming and outgoing neutrons, and a pairof parallel plate magnets (PM1, PM2) and solenoid coils(B1, B2), which are auxiliary magnets, are placed on bothsides of HC, connecting the magnetic field to the permanent guide field in BL17. The designed applied magnetic
field to the sample is 0.5 to 10 mT. A heat sink is attachedto the coil surface for air cooling, and a protective frame
exists to cover the heat sink. The coil temperature is designed to be less than 48°C. The design is supposed toprevent the risk of fire accident or burns from humancontact. Furthermore, it is equipped with a safety interlock that automatically shuts down the power supply inthe event of electrical leakage or coil overheating. A GM
4 K type cryostat can also be mounted, allowing experiments from 4 K to room temperature. Figure 2 shows thepolarization state |P1∙P2| of the neutron beam at 0.9 mT
using the HC magnet, which is the product of the polarization ratios, P1 and P2, for the polarizers in front of thesamples and detectors, respectively. The result indicates

Figure 1. Schematic figure of field connection.

Figure 2.	Comparison of polarization states in magnetic
fields of 0.9 mT and 1 T.

MLF Annual Report 2021

Neutron Sciencethat |P1 ∙ P2| is 92% or higher in neutron wavelengthfrom 0.22 nm to 0.77 nm. Compared to |P1 ∙ P2| in a 1 T
magnetic field in an electro-magnet, the performanceis confirmed to be comparable to the existing sample
environment. This polarization is also confirmed to bealmost unchanged from 0.25 to 6.2 mT. This system isavailable for user experiments.
3. Deep learning for noise reduction
Because of the limitation of the beamtime in neutron experiment facilities, it has been demanded toshorten the measurement time. However, the reduction in the acquisition time introduces a large statisticalnoise in the obtained data, resulting in a false structure
information from the data analysis. A deep learningtechnique was developed as a novel method for accelerating the data acquisition without compromising
the accuracy of the data analysis [2]. The removal of thestatistical noise from the NR data taken in a short acquisition time reduces the measurement time in the NR
experiment. Here, we developed a convolutional neuralnetwork (CNN) for NR and demonstrated the accurate
data analysis for the NR data which was obtained in a
ten-time shorter measurement time compared with theconventional experiment.
A neural network with hidden layers consisting of
one-dimensional convolution, batch normalization,and rectified linear unit was used for supervised deeplearning. The data set for the training was generated by
the neutron event simulator developed for SHARAKU.
More than 200000 layered structures were generated,then the theoretical NR profile was calculated and theexperimental NR data with a short acquisition time wassimulated for each structure as the supervising andinput data for deep learning. The blue circles in Fig. 3
show the experimental data in a 20-fold shorter acquisition time compared with a conventional experiment.
On the other hand, the green curve in Fig. 3 indicatesthe data obtained by a longer acquisition time, indicating the low noise in the NR data. Comparing them, theFigure 3.	Statistical noise in the NR data obtained in a shortmeasurement time (blue circles) is removed by the
deep learning-based technique. The resultant NR
data (red) is in good agreement with the ideal data
without statistical noise (green curve).

NR data points taken in the short acquisition time arescattered by the large statistical noise. The red circles inFig. 3 were obtained by removing the noise component
from the NR data taken in the short time (blue data in
Fig. 3) by data processing with the deep learning. The
processed data is in good agreement with the NR data
without noise (green curve). This indicates that the deeplearning-based noise reduction method enables the
reduction of the measurement time by over 10 times
without a loss of the accuracy of the experimental data.
This method will considerably improve the time
resolution in an operando measurement to examine
the time evolution of the interface structure. Moreover,it will allow state-of-the-art methods which require
unrealistic beamtime in conventional instruments [3].
This noise reduction function based on deep learning
will be implemented in the analysis web application for
SHARAKU and it would open a new horizon in surface/interface science.
References[1] Y. Zhong et al, AIP Advances, 10, 015323 (2020).
[2] H. Aoki et al, Sci. Rep., 11, 22711 (2021).
[3] H. Aoki et al, Langmuir, 37, 196 (2021).

H. Aoki1,2, T. Hanashima3, K. Soyama4, D. Yamazaki5, N. Miyata3, K. Akutsu3, and S. Kasai3
Neutron Science Section, Materials and Life Science Division, J-PARC Center; 2Institute of Materials Structure Science, KEK; 3Neutron
Science and Technology Center, CROSS; 4Administration and Operations Support Division, J-PARC Center; 5Neutron Instrumentation Section,
Materials and Life Science Division, J-PARC Center
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Status of SENJU 2021
1. Introduction
SENJU is a TOF single-crystal neutron diffractometer designed for precise crystal and magnetic structure
analyses under multiple extreme environments, suchas low-temperature, high-pressure, and magnetic-field,
as well as for taking diffraction intensities of small single crystals with a volume of less than 1.0 mm3 down
to 0.1 mm3 [1]. Since the operation of SENJU started in2012, our instrument group has carried out continuous
commissioning and upgrades.
In 2021, we developed a sample stick with an automatic sample changer, an automatic data-processing
wizard for the STARGazer-Online, and a multi-crystal
data processing method. In addition, we also report on
the purposes of the instrument beam-time for SENJU.
2.	Development of a sample stick with an automatic
sample changer
Selecting a good quality sample crystal is one of themost crucial points for single-crystal neutron diffraction
measurement. Screening of single crystals is often carried out to find a good quality single crystal, but it takes
a long time and requires human resources to change
the sample. We developed a sample stick with an automatic sample changer to achieve the sample screening automatically. The sample stick has five aluminum
sample trays to set candidate crystals for measurement.
The trays are arranged along the vertical direction andcan move in upper and lower directions. The distance
between the two trays is 50 mm, and only one of thetrays is in the direct beam. The movement of trays is controlled by using the IROHA2 system. Suppose a SENJU
user has several candidates of crystal for measurement.
In that case, the user can find the most qualified single
crystal by setting the crystals in the trays and performing sequential diffraction measurements using the sample stick.
3.	Automatic data processing wizard for the
STARGazer-Online
STARGazer-Online is a data processing applicationfor SENJU, which works on several types of web browsers (Chrome, Safari, and Firefox). The application is madefrom several functional components, and SENJU users
have to execute each component in the correct orderto process the SENJU diffraction data correctly. So, forbeginners of the single-crystal diffraction technique,using STARGazer-Online has been a complicated task.
114

To solve this problem, we developed an automatic dataprocessing wizard for the STARGazer-Online.
This wizard requires only specific information foreach experiment, such as run numbers, sample environment device, and minimum d-spacing. The wizard
automatically determines the cell parameters and UB
matrix, integrates Bragg peak intensities, and outputs
reflection files available for some structure refinement
software such as JANA2006 and SHELXL. After determining cell parameters and UB matrix refinement, theuser can verify whether the data processing proceeds
appropriately. After the intensity integration, the obtained intensity distribution of the Bragg reflection isdisplayed as a summary. The wizard makes the SENJU
data processing more accessible. We expect the users toiterate the data processing more comfortably and findthe optimal data processing conditions for their diffraction data to produce high-quality structural refinement.
4.	Development of a multi-crystal data processing
methodOne of the severe problems in single-crystal neutron diffraction is the sample volume. The time requiredfor data collection at SENJU is expressed as “measurement time per crystal orientation” times “number oforientations,” where the “measurement time per crystal
orientation” is determined by the incident beam intensity and sample volume. Therefore, to measure small
samples in the limited beam time without increasing thedirect beam intensity or sample volume, reducing the“number of orientations” is essential. To achieve this purpose, we investigated the multi-crystal measurement, inother words, the simultaneous diffraction measurementof multiple single-crystal samples. By measuring several
crystals simultaneously, data for different orientations
can be obtained at once, which is expected to reduce
the overall measurement time.
One of the essential points in the multi-crystal
measurement is determining the UB matrix for every
single crystal, and we tried the “auto two-Bragg indexing method” proposed by T. Sakakura [2]. This method
requires the cell parameters and proceeds as follows:
1. Find Bragg peaks from the raw data and calculate
the scattering vector in the reciprocal space foreach Bragg peak.
2. Calculate the absolute length of each scatteringvector and assign the presumable index estimatedfrom the cell parameters.

MLF Annual Report 2021

3. Select any two peaks and calculate the UB matrix
by the two-Bragg method.
4. Calculate the indexes of other peaks by the UB matrix. The matrix is accepted if reasonable indexes
are assigned to peaks above the threshold. If not,the matrix is rejected.
5. Remove the indexed peaks and repeat processes 3
and 4 till all peaks are indexed.
We tested this method with ruby crystals. We measured diffraction data with three ruby crystals and six
ruby crystals. The crystals’ size was φ1.0 mm, and themeasurement time was 1 hour for both conditions. The
auto two-Bragg indexing method worked well for bothdiffraction data, and suitable UB matrices for all rubycrystals were successfully obtained.
The integration intensities of the Bragg peaks andNeutron Sciencestructure refinement following the UB matrices determination worked well for the three crystals data, while theinfluence of peak overlapping became unignorable forthe six crystals data. The next challenge is the intensity
integration of the overlapping Bragg peaks, and we are
now testing some methods.
5. Use of the instrument beam time
In 2021, the instrument beam time was used mainly
for measurements of standard samples, and a vanadium-nickel alloy for calibration of the detector efficiency.
References[1] T. Ohhara et al., J. Appl. Cryst., 49 120 (2016)[2] T. Sakakura, CrSJ meeting (2019)

T.Ohhara1, R. Kiyanagi1, A. Nakao2, K. Munakata2, Y. Ishikawa2, K. Moriyama2, I. Tamura1, and K. Kaneko1
Neutron Science Section, Materials and Life Science Division, J-PARC Center; 2Neutron Science and Technology Center, CROSS

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Engineering Material Diffractometer TAKUMI
1. Introduction
TAKUMI is a neutron diffractometer dedicated forresearch in engineering materials sciences, which was
installed at Beamline 19 in the MLF of J-PARC. Carefulanalysis of the Bragg peaks in a neutron diffraction pattern can reveal important structural details of a sample
material, such as internal stresses, phase conditions,dislocations, texture, etc. Experiments in TAKUMI varyfrom internal strain mapping in engineering components, microstructural evolutions during deformationsof structural or functional materials at various temperatures, microstructural evolutions during manufacturing(thermo-mechanical) processes, to texture analyses ofengineering materials.
2. User program and publications
In FY2021, 28 general-use programs, 1 long-term
program and 1 project-use program were successfully
conducted on TAKUMI. Note that due to the effects of the
COVID-19 restrictions, 7 experiments were performed bybeamline staff on behalf of users. The statistics about
the experimental types and the sample materials of theexperiments conducted during FY2021 are summarized
in Fig. 1. More than 60% of the beamtime was occupied
by in-situ measurement during a loading test. On theother hand, 24% of the beamtime was used for strain
mapping experiments for internal strain (stress) analysis of mechanical parts. Iron and steel, because of theirimportance as structural materials, accounted for 41%of the total samples. Summarizing the percentages forlight metals (Al-, Mg- and Ti-based alloys, 19%) and metals and alloys (Ni-based superalloy, high-entropy alloys
and other alloys, 32%), 91% of the beamtime was used
for experiments with metallic material samples. In contrast, the percentage of experiments with non-metallic
samples (rocks and ceramics) was only 5%.
Thanks to the efforts of the users and the collaborators, 20 papers and 1 proceedings paper using the datameasured at TAKUMI have been published in FY2021.
The statistics on experimental types and sample materials used in papers published during FY2021 are summarized in Fig. 2. In addition, the data were also used in
1 doctoral thesis and 1 master’s thesis. Some highlightsof the papers are introduced below:

116(a)	“Stacking fault driven phase transformation in
CrCoNi medium entropy alloy”, by Haiyan He, etal. [1]. A bulk fcc-to-hcp phase transformation in
CrCoNi medium entropy alloy at 15 K under tensileloading was revealed by in-situ loading study withneutron diffraction.
(b)	“Quantifying internal strains, stresses, and dislocation density in additively manufactured
AlSi10Mg during loading-unloading-reloading
deformation”, by Xingxing Zhang, et al. [2]. In-situ
neutron diffraction is employed to explore the residual strains, stresses, and dislocation density in
the AlSi10Mg alloy manufactured via laser powder
bed fusion during loading-unloading-reloading
deformation.
(c)	“Effect of deformation-induced martensitic transformation on nonuniform deformation of metastable austenitic steel” by Wenqi Mao, et al. [3].
A digital image correlation technique combinedwith in-situ neutron diffraction was used for the
first time to investigate the Portevin–Le–Chatelier(PLC) behavior in an Fe–24Ni–0.3C steel.
(d)	“Analysis of residual stress in steel bar processedby cold drawing and straightening”, by Satoru
Nishida, et al. [4]. The internal residual stress distributions in a free-cutting steel bar processed bycold drawing and straightening were investigatedby neutron diffraction technique.
3. Upgrades and maintenances
The following upgrades and maintenance were performed to make TAKUMI more user-friendly and morestable in FY2021:(1)	The use of a new sample chamber developed for
low-temperature deformation tests began on a
trial basis. More rapid temperature changes andsimplified sample exchange were realized by thischamber.
(2)	The lighting in the radiation shielding chamber
and the camera system for observing the sample
were updated. These allow more accurate sample
positioning.
(3)	Some of the detector electronics and the DAQ electronics, which had aged due to more than 10 yearsof operation, were updated.

MLF Annual Report 2021

Neutron Science

Figure 1.	The statistics of (a) the kinds of experiment which were conducted at TAKUMI and (b) the kinds of material usedin these experiments in FY2021. The percentages shown indicate the beamtime (in days).

Figure 2.	Statistics on (a) the types of experiments performed at TAKUMI and (b) the types of materials used in those experiments for papers using TAKUMI published during FY2021. The percentages shown indicate the beamtime (indays).

References[1] H. He, M. Naeem, F. Zhang, Y. Zhao, S. Harjo, T.
Kawasaki, B. Wang, X. Wu, S. Lan, Z. Wu, W. Yin, Y. Wu,
Z. Lu, J-J. Kai, C-T. Liu, X-L. Wang, Nano Letters, 21,1419-1426 (2021).
[2] X. Zhang, H. Andrä, S. Harjo, W. Gong, T. Kawasaki,
A. Lutz, M. Lahres, Materials & Design, 198, 109339(2021).

[3] W. Mao, W. Gong, T. Kawasaki, S. Harjo, Materials
Science and Engineering: A, 837, 142758 (2021).
[4] S. Nishida, S. Nishino, M. Sekine, Y. Oka, S. Harjo,
T. Kawasaki, H. Suzuki, Y. Morii and Y. Ishii, Materials
Transactions, 62, 667-674 (2021).

T. Kawasaki1, W. Gong1, W. Mao1, S. Harjo1, and K. Aizawa2
Neutron Science Section, Materials and Life Science Division, J-PARC Center; 2Materials and Life Science Division, J-PARC Center

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The Current Status of the Versatile Neutron Diffractometer,
iMATERIA
1. Introduction
Ibaraki Prefecture, local government of Japan’s area
where the J-PARC sites are located, has decided to build
a versatile neutron diffractometer (IBARAKI Materials
Design Diffractometer, iMATERIA [1]) (fig. 1) to promoteindustrial applications for the neutron beam in J-PARC.
iMATERIA is planned to be a high-throughput diffractometer that could be used by materials engineers andscientists in their materials development work, including chemical analytical instruments.
The applications of neutron diffraction in materials
science are (1) to do structural analyses of newly developed materials, (2) to clarify the correlation between
structures and properties (functions), and (3) to clarify
the relation between structural changes and improvements of functions, especially for practical materials. A
diffractometer with super high resolution is not required
to achieve those goals. The match of features like intermediate resolution around Δd/d = 0.15%, high intensity
and wide d coverage is more important.
This diffractometer is designed to look at a decoupled-poisoned liquid hydrogen moderator (36 mm, offcentered) (BL20), and it has an incident flight path (L1)of 26.5 m, with three wavelength selection disk-choppers and straight neutron guides with a total length of
14.0 m. The instrumental parameters are listed in Table 1.

There are four detector banks, including a low-angle andsmall-angle scattering detector bank. The angular coverage of each detector bank is also shown in Table 1. The
rotation speeds for the disk-choppers are the same, witha pulse repetition rate of 25 Hz for the most applications(SF mode). In this case, the diffractometer covers 0.18
< d (Å) < 2.5 with Δd/d = 0.16% and covers 2.5 < d (Å) <800 at three detector banks of 90-degree, low-angle andsmall-angle with gradually changing resolution. Whenthe speed of the wavelength selection disk-choppers is
reduced to 12.5 Hz (DF mode), we can access a wider
d-range, 0.18 < d (Å) < 5 with Δd/d = 0.16%, and 5 < d (Å)< 800 with gradually changing resolution with doubled
measurement time compared to the SF mode.
2. Current status
All of the four banks, high-resolution bank (BSbank), special environment bank (90-degree bank),
low-angle bank and small-angle bank, are operational. It
takes about 5 minutes (in DF mode) to obtain ‘Rietveldquality’ data in the BS bank at 700 kW beam power for
about 1 g of standard oxide samples.
Figure 2 shows a typical Rietveld refinement pattern for LiCoO2 sample, cathode material for lithium-ion
battery (LIB), at the BS bank by the multi-bank analysis function of Z-Rietveld software [2]. It takes 20 min

Table 1.	Instrumental parameters of iMATERIA. L2 is thescattered flight path. The d-range (q-range) for
each bank is the maximum value for 2-measurement mode.

Figure 1.	IBARAKI Materials Design Diffractometer, iMATERIA
without detector for each bank and instrument
shielding. The BS bank, 90-degree bank, and lowangle bank, can be seen from right to left. The
small-angle detector bank, which is not shown in
the picture, is situated in the low-angle vacuum
chamber (left-hand side of the picture).

118

L1
Guide length
Position of Disk choppers

26.5 mHigh
Resolution
Bank
SpecialEnvironment
Bank
Low
Angle
Bank
Small
Angle
Bank

2θ
L2
d-range2θ
L2d-range2θ
L2d-range2θ
L2
q-range

Total 14 m (3section)
7.5 m (double)
11.25 m (single)
18.75 m (single)
150˚ ≤ 2θ≤ 175
2.0 – 2.3 m
0.09 ≤ d (A˚) ≤ 5.0˚
80˚ ≤ 2θ≤ 100˚
1.5 m
0.127 ≤ d (A˚) ≤ 7.2
10˚ ≤ 2θ≤ 40˚
1.2 – 4.5 m
0.37 ≤ d (A˚) ≤ 58
0.7˚ ≤ 2θ≤ 5˚
4.5 m
0.007 ≤ q (A˚–1) ≤ 0.6

MLF Annual Report 2021

Neutron Sciencesystem for LIB with a sample changer is available in cylindrical, coin and laminated types of batteries.

Figure 2.	Rietveld refinement pattern for LiCoO2 at the BS
bank of iMATERIA.

in DF mode to collect the available Rietveld data, due
to the high neutron absorption cross section for natural
Li (σsNat = 70 barn).
3. Sample environments
The automatic sample changer is the most important sample environment for high-throughput ex-periments. Our automatic sample changer [3] consists of asample storage, elevating system of two lines, two setsof pre-vacuum chambers and a sample sorting system.
We can handle more than 600 samples continuously atroom temperature (RT) without breaking the vacuum of
the sample chamber.
The vanadium-furnace (~900°C), the gas flow furnace (~1000°C), and the 4 K and 1 K cryostats are readyfor experiments.
The rapid heating/quenching furnace with automatic sample changer (RT – 1273 K with heating speed
10 K/s and cooling speed >20 K/s) [4] and the universal
deformation testing machine (max loading 50 kN with
RT – 1273 K) [5] are available for texture measurements.
The in-operando charge and discharge measurement

4. Development of multiscale measurement method
for fuel cell materials
We have developed a new glass slit (fig. 3) for multiscale measurement. This slit makes it possible to simultaneously measure small-angle scattering and wide-angle
diffraction to obtain structural information.
We also have measured the battery materials using
the developed technology and clarified their structural parameters. [6] This method will enable multi-scalemeasurements of electrolyte and electrode materials
from crystal structure to nano-level structure, which isnecessary for improving solid fuel cell performance.

Figure 3. The newly developed glass slit.

References[1] T. Ishigaki, et al., Nucl. Instr. Meth. Phys. Res. A 600(2009) 189-191.
[2] R. Oishi, et. al., Nucl. Instr. Meth. Phys. Res. A 600(2009) 94-96.
[3] A. Hoshikawa, et al., J. Phys.: Conf. Ser. 251 (2010)
012083.
[4] Y. Onuki, et. al., Metall. Mat. Trans. A. 50 (2019)4977-4986.
[5] Y. Onuki, et. al., Quantum Beam Sci., 4 (2020) 31.
[6] H. Takahashi., Prepare for publication.

T. Ishigaki and A. Hoshikawa
Frontier Research Center for Applied Nuclear Sciences, Ibaraki University

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Status of the High Intensity Total Diffractometer (BL21, NOVA)
1. Introduction
Total scattering is a powerful technique to analyze
non-crystalline structure in materials with atomic Pair
Distribution Function (PDF). NOVA was designed to perform total scattering and is the most intense powder diffractometer with reasonable resolution (Δd/d ~ 0.5 %)in J-PARC. It is easy to adapt NOVA to a wide variety offields: liquids, glass, local disordered crystalline, magnetic structure of long lattice constant and so on.
2. Installation of 3He cryostat
Since the introduction of the radial collimator(NOVARC) [1], which is effective in reducing backgroundfrom sample environment (SE) equipment, NOVA has
been expanding the use of common SE ones managed

by the SE team. In 2021, we installed the 3He cryostat(common SE equipment) and implemented the linkage system between EPICS control and the IROHA2 sequence server.
As for the control system, the 3He cryostat is controlled by a PLC manufactured by Keyence Co. With
the cooperation of Mr. Y. Yamauchi (NAT) and Mr. R.
Takahashi (JAEA) in the SE team, Mr. Y. Yasu (KEK) constructed a system that controls the PLC via the EPICS GUI
tool (CSS GUI), which is commonly used in accelerator
control software, and an online monitor for temperatureusing Grafana GUI software (Fig. 1). The measurement
sequence is automatically controlled by sending commands from the IROHA2 sequence server to the EPICS
through a façade (Fig. 2).

Figure 1.	Temperature logging with Grafana GUI software.

Figure 2.	Automatic measurement sequence with IROHA2 sequence server and CSS GUI.

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Using these systems, we performed neutron diffraction experiments using ErF3, which has an antiferromagnetic phase transition at TN = 1.05 K and shows a
non-collinear magnetic structure [2]. The powder sample was provided by BL08. Figure 3(a) shows the scattering profile of the 10-minute measurement, Fig. 3(b)indicates the temperature dependence of the integrated intensity of the magnetic scattering Bragg peak
100 (d ~ 6.4 Å), which reflects the antiferromagnetic
magnetic structure, and Fig. 3(c) exhibits the temperature dependence of the diffraction profiles. The temperature is that of the sample stage.
We observed that the integrated intensity of themagnetic scattering peak below the transition temperature increased order parametrically with temperature
cooling. From the results, we confirmed that the 3He cryostat experiment was feasible for NOVA.

Neutron Science

We have also prepared the manuals for EPICS (User’s
Guide for Control, Monitoring, and Archive System)and the one for the 3He cryostat experiment at NOVA.
Furthermore, the experiment with these systems installed at BL02 was successfully completed.
Acknowledgement
We would like to thank Mr. H. Maya for his technical support in operating NOVA. The operation and developments of NOVA was performed under the S1-type
program (2019S06) approved by the Neutron Scattering
Program Advisory Committee of IMSS, KEK.
References[1] K. Ikeda et al., MLF Annual Report 2017, 110-111.
[2] K. Kramer et al., Eur. J. Solid State Inorg. Chem. 33,
273 (1996).

Figure 3.	(a) 10-minute measurement profile of ErF3 at the lowest temperature, (b) temperature dependence of integrated intensity of 100 magnetic scattering peaks, and (c) temperature dependence of the diffraction profiles.

T. Honda1,2,3, K. Ikeda1,2,3, T. Otomo1,2,3,4, H. Ohshita1,2, and M. Tsunoda4
Institute of Materials Structure Science, KEK; 2Neutron Science Section, Materials and Life Science Division, J-PARC Center; 3Department
Materials Structure Science, The Graduate University for Advanced Studies, SOKENDAI; 4Graduate School of Science and Engineering,
Ibaraki University

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Current Status of the Energy-Resolved Neutron Imaging
System RADEN
1. Introduction
The Energy-resolved neutron imaging system“RADEN”, installed at beamline BL22 in the MLF of
J-PARC, is a dedicated instrument for wavelength/energy-dependent neutron imaging experiments, which
utilizes fully the short-pulsed neutron’s nature [1]. A
variety of imaging experiments have been conducted
at RADEN, such as Bragg-edge imaging, neutron resonance absorption imaging, and polarized pulsed neutron imaging, in addition to the conventional neutron
imaging. RADEN started the user operation in 2015, andafter that, about 40 user programs have been conducted every year. In this report, the results of the technicaldevelopment and remarkable application studies conducted at RADEN are described.
2.	Energy-selective imaging by fast-gate image
intensifier system
A neutron imaging detector system consisting of a
CMOS camera and an optical image intensifier (I.I.) has
been developed for a neutron energy/wavelength selective imaging [2]. The fast gate operation of the optical I.I., which opened or closed the electronic shutter
very quickly by an external trigger signal, was utilized
to select neutron energy/wavelength by amplifying theincident light from the scintillator during a given Timeof-flight (ToF) period. The output light signal from the
I.I. was accumulated by the CMOS sensor, and an image,which had information only from the selected neutronenergy/wavelength, was created (see Fig. 1). Because
the delay and the width of the timing gate was controlled by applying a pulsed electric signal to I.I. using a
digital delay generator, neutron energy selection could

be done in an easier and quicker way compared withthat by using the chopper system. Moreover, it is beneficial that this system allows to easily adjust the fieldof view and the spatial resolution suitable to the object
and that exposure time needed to obtain one image isvery short in comparison with the counting type image
detectors. However, when spectral analysis with fineenergy/wavelength resolution is required, the use ofcounting type detectors is more suitable than this camera system. Because the accessible energy resolution ofthis system is relatively coarse (around 1%), scanningthe delay of the timing gate is needed to obtain spectra.
As application of this system, we have visualized
iced and liquid water distributions by neutron energy selective imaging [2]. In our previous work, we conducted
spectral analysis by using event type detector position
by position [3], but we obtained images at two different
neutron energies and divided their transmission images
to produce an image to identify iced and liquid water
distribution in this work. The resulting images are shownin Fig. 2. The exposure time was effectively decreased,
and a large field of view could be realized.
3.	Application study: visualizing water distribution
in a driving fuel cell
The water visualization in a fuel cell used in the Fuel
Cell Electric Vehicle (FCEV) has been conducted under
the FC-Platform program supported by NEDO. A commercial full-size single fuel cell installed in the second
generation TOYOTA MIRAI was used for the experiment.
In order to carry out the operation of the fuel cell inside the shielding of RADEN beamline and to conduct
in-operando imaging experiments, we have prepared a

Figure 1.	A schematic illustration of energy/wavelength selective neutron imaging using an optical I.I. with fast gate function. Bymeans of the time gate, synchronized with the neutron pulse generation, it is possible to amplify the incident light fromthe scintillator screen only a given ToF and produce an image of selected neutron energy.

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special equipment. At first, RADEN was equipped witha gas-supply system, a hydrogen dilution unit with nitrogen gas generator, hydrogen gas monitors, and leakdetectors as safety devices. A fuel cell operation kit anda load unit were brought from the automobile company.
And then, constraint plates for the cell assembly were
designed by taking into account the neutron transmittance. These works were all done under the collaboration with several automobile companies.
Figure 3a shows the experimental setup of the fuelcell assembly. The cell was operated along the practical test procedure for the fuel cell of FCEV, and the load
performance test was conducted. The neutron imaging
experiments were performed by using a camera typedetector system consisting of a CMOS camera and an
optical I.I.. The exposure time was 1 sec, and it was repeated 300 times. The distribution image of generated
water was derived by dividing an image obtained during the cell operation with that of a dried cell. The resultsof the load performance test clearly indicated different
water distribution as load conditions. In addition, theamount of observed water was very little, and the shapeof the channel was not observed clearly (Fig. 3b).

Neutron Science

Figure 2.	Example of visualization of iced and liquid water
distribution by using energy selective neutron imaging [2]. Liquid water is represented with red colorand iced water is indicated with blue.

4. Summary
RADEN is used in various fields, not only scientific
but also industrial, and its application has been spreading widely. The RADEN group continues the development works on devices and on imaging techniques anddemonstration studies so as to promote user programsfrom broader fields.
References[1] T. Shinohoara et al., Rev. Sci. Instrum., 91, 043302(2020).
[2] K. Isegawa et al., Nuclear Inst. and Methods inPhysics Research, A 1040, 167260 (2022).
[3] Y. Higuchi et al., Phys. Chem. Chem. Phys., 23, 1062
(2021).

Figure 3.	Neutron imaging experiment of the commercial
fuel cell used in FCEV. (a) A photograph of the experimental setup of cell assembly. (b) A water distribution image obtained by neutron imaging.

T. Shinohara1, T. Kai1, K. Oikawa1, Y. Tsuchikawa1, K. Isegawa1, K. Hiroi1, Y. Su2, H. Hayashida3, J. D. Parker3, Y. Matsumoto3,
and Y. Kiyanagi4
1
Neutron Science Section, Materials and Life Science Division, J-PARC Center; 2Technology Development Section, Materials and Life Science
Division, J-PARC Center; 3Neutron Science and Technology Center, CROSS; 4Hokkaido University

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Polarized Neutron Spectrometer POLANO
1. Introduction
POLANO is a direct geometry chopper spectrometer with middle energy and spatial resolution. For the
purpose of high-efficient polarization experiments ininelastic scattering technique, the POLANO was optimized for high transfer energy (HTE) polarization analysis [1–3]. The POLANO opened to a part of user program
since 2019 with only unpolarized neutron experiment.
Some of the unique techniques and ideas of time-offlight (tof ) method with a so-called event recording
data acquisition processes came up. The omega-rotation
measurement is one of the excellent ways which enables us to measure entire four-dimensional momentum
Q (qx, qy, qz) and energy E spaces. POLANO can also be
available to measure the inelastic signals with the multi-Ei technique, though this is not new technique but
resulting event recording system of the tof method.
Utilizing the above-mentioned technique, a reasonable quality of data is being obtained, and scientificresults (articles) will be generated using the POLANO
spectrometer.
We also made significant efforts to develop andinstall polarization devices, including magnetic andrelated devices in order to realize the HTE polarization.
The HTE polarization can be realized by combining SEOP
(spin exchange optical pumping) 3He gas spin filter with
5.5 Qc bending mirror analyzer, as explained in the following section. However, even with this technique,the utilized neutron energy is restricted up to around
Ef = 45 meV for out-going analyzed neutron energy (final neutron energy) by the reflecting capability of themirrors. But our final goal for HTE is 100 meV beyond thereactor-based neutron polarization energy.

2. Polarization and magnetic devices
As reported last year, the safety assessment for thelaser system and the magnetic device (Helmholtz-coils)
has been completed. After addressing some of the issues raised, those devices were installed in the beamline, and test experiments have been performed.
1) SEOP polarizer system:
POLANO is using 3He gas filter known as SEOP system for a polarizer. SEOP system used as a polarizer in
POLANO has been under development for a long time.
We were making efforts to realize a higher performancedevice for rather high energy neutron.
The evaluated figure of merit P2T (P: polarization of3
He spins, T: transmission of neutrons) was optimized for
100 meV neutron energy with the result of 30 atm • cm
for 3He gas. The glass cell containing 3He and other gases
was originally made in-house using GE180 glass material
and reached 80% of 3He spin polarization. Finally, thesystem has been installed on the beamline for practicaluse. Figure 1 shows the setup of the SEOP system on the
POLANO beamline. A black box containing optical andlaser devices in addition to the 3He cell is the main component for the polarizer. The SEOP box and the newly installed straight collimator made of B4C neutron absorber
are on a trestle with vertical driving mechanism, whichenables us to swap polarization and unpolarization experiments easily.
2) Magnetic system:
Another crucial item is the magnetic field. The magnetic field is essential for defining quantization axis andkeeping the neutron spin polarization as a guide field.

laser and op�cs

guide coilsolenoid coils
low-noise ampliﬁer
for NMR

Figure 1.	Left: Newly installed setup of the SEOP system. Neutron direct beam goes through the black box (SEOP box), where a glass
cell for the 3He gas filter is positioned. Right: The suite of magnets including SEOP 3He polarizer and other optical devices.

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Also, indispensable for controlling the spin directions
and flipping the spins at a certain position. POLANO’s
whole magnetic system is composed of several devices
like 1) SEOP system (combination of a solenoid coil andtwo convergence coils), 2) guide field at the entranceof the vacuum chamber made of neodymium boron
permanent magnet, 3) asymmetric Helmholtz coils(HC) at the sample position, 4) fan-shaped magnet after
the sample, then 5) analyzer mirror (yoke). A development of the HC system and innovative design of the fanmagnet can be a key to the entire magnetic system of
POLANO. As shown in Fig. 2, the final tests of the HC on
the POLANO beamline were carried out. In Fig. 2 on theleft, the calculated magnetic field by the set of magnetic
devices (analyzer mirror not included) and the actually

Neutron Sciencemeasured field by 3-dimensional Gauss meter are compared. Both are in good agreement though the ambient
magnetic conditions are different.
The HC and its control system were also tested on
the beamline. The new design of the installed HC canapply the magnetic field with 20–30 Gauss to any direction in the horizontal plane by adjusting the current of
three horizontal coils (H1, H2, and H3) (Fig. 3, left). The
magnetic field at sample position yielded by individual
coils was measured with changing the current for thecoils (Fig. 3 right). Based on these validation test results
a remote controlling system was produced, which willallow us to change the conditions and check the status
via the YUI program, the main program controlling all
devices.

Figure 2.	Newly designed fan-shaped magnet. Left: The measured and evaluated magnetic field at each position on the beamline.
Right: The magnetic test in the beamline.

Figure 3. Helmholtz coils and evaluated electric current for maximizing the magnetic field on every scattering direction.

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3. Fermi chopper issue
Fermi chopper is one of the key devices used formonochromatizing incoming neutron energies. But lastyear, we had a very serious and unexplained trouble on
the Fermi chopper. The control on phasing was lost because of rotation signal failure. Since we use optical sensors for detecting the rotation, all the circuits, including
the sensors, were renewed and the electrical board was
re-designed. We also updated the payload (rotor) withall new design. This new rotor has been optimized togain more neutron flux but is losing some of the energy
resolution. Still, the problem has not yet been resolved,
and we will continue to work toward a solution.
4. In summary
In this year we have made significant efforts torefurbish and optimize the devices for the upcoming

polarization experiments. Now the POLANO is almost
ready to launch a polarization experiment via on beam
test at MLF beamline BL23. In addition to beam commissioning, developments and updating devices and methods are indispensable to realize spherical polarimetry
with pulse neutron beam. In particular, the R&D of newdevices, such as a spin flipper after the sample, high polarization 3He filter, and large solid angle SEOP analyzer
for the future HTE polarization.
References[1] T. Yokoo, et al., EPJ Web of Conferences, 83 03018(2015).
[2] T. Yokoo, et al., AIP conference proceedings, 1969050001 (2018).
[3] MDPI Books, Quantum Beam Science 162 (2019).

T. Yokoo1,2, N. Kaneko1,2, D. Ueta1,2, S. Itoh1,2, S. Yamauchi1,2, K. Hayashi1, T. Ino1,2, and M. Fujita3
Institute of Materials Structure Science, KEK; 2Neutron Science Section, Materials and Life Science Division, J-PARC Center; 3Institute forMaterials Research, Tohoku University

1

126

MLF Annual Report 2021

Neutron Science

Sample Environment at the MLF
1. Introduction
The MLF sample environment (SE) team provides
the sample environment equipment that is sharedfor use among the MLF beamlines, the so-called BLcommon equipment. The equipment is upgraded according to users’ demands. The equipment that can
produce extreme sample conditions is also developed.
2. Cryogenics and magnets
We have five pieces of the BL-common cryogenic
equipment. In JFY2021, (1) the superconducting magnet
was operated for 11 experiments, (2) the 4He cryostat for
8 experiments, (3) the 3He cryostat for 10 experiments,(4) the 3He-4He dilution refrigerator (DR) insert for 12 experiments and (5) the Gifford-McMahon cryofurnace for
2 experiments, including instrument proposals. The equipment was in use for 198 days in total.
The DR was used on SHARAKU (BL17) for the first time,
combined with the superconducting magnet. To use the
DR on SHARAKU, the metal flexible line that connects thegas handling system with the DR insert (Fig. 1) had to beextended from the original length of 3 m because there
was no room to place the gas handling system near the
DR insert, which was inserted in the magnet in the shielding hutch of SHARAKU. The length of the metal flexible line
was optimized to be 5 m through test experiments and theattainable lowest temperature at the length condition wasalmost the same as the original one.
The 3He cryostat was used on NOVA (BL21) for the
first time. On NOVA, the height of the top flange of thevacuum chamber from the beam center is 250 mm
higher than the MLF standard. Therefore, an extension
was added in the outer vacuum chamber, the radiation shields and the sample stage of the 3He cryostat
to adjust the height (Fig. 2). There was no change in
the attainable lowest temperature, 0.3 K, by the extension although the cooling time from room temperature
to the lowest temperature was extended from 19 to
25 hours.
Temperature control of the 4He cryostat of POLANO(BL23) was significantly improved by precisely controlling temperatures of two heaters in the cryostat. Figure 3
shows the result of the temperature control of the cryostat from 5 to 250 K. Below 50 K, the temperature at
the sample position was controlled within the accuracyof ± 0.04 K.

Figure 1.	Left: the gas handling system of the DR on theshielding hutch of SHARAKU. Right: the DR systemcomposed of the DR insert, the gas handling system, and the metal flexible line.

Figure 2.	Extension of the outer vacuum chamber (A), the radiation shields (B), and the sample stage (C).

Figure 3.	Temperature control of the 4He cryostat of POLANO
from 5 to 250 K.

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3. Low and high temperatures
The exact temperature at the sample position of thecryofurnace of SuperHRPD (BL08) was examined in therange from 181 to 401 K, by observing the phase transition of a BaTiO3 single crystal. It was verified from thestudy that the temperature at the heater was the sameas that at the sample position.
4. High temperatures
We installed a remote monitoring system for the niobium furnace and received an approval for its use from
the MLF equipment safety team in JFY2020. This remotemonitoring system was used for the users’ experiment
on SENJU (BL18) for the first time in JFY2021 (Fig. 4).
According to the MLF regulations, the user and/or staff
should be present at all times to monitor the furnace forabnormal behavior or fault. However, the installation of
the monitoring system released the users and/or staff
from the monitoring task throughout the experiment.
5. A pulsed magnet system
In JFY2021, a new coil was developed to obtainpulsed magnetic fields of up to 35 T higher than theprevious maximum magnetic field of 30 T. The coil iswound with 1 × 1.5 mm rectangular wire, which is madeof a high-tensile strength Cu–Ag alloy (Fig. 5). It has inner and outer diameters of 14 and 50 mm, respectively,
with the axial length of 21 mm. The inductance and resistance of the coil, immersed in liquid nitrogen, havebeen measured using an LCR meter (3522–50, HIOKI) at
100 Hz and a mΩ Hi-Tester (3540, HIOKI), respectively.
The measured inductance and the resistance at 77 K are
369 μH and 60 mΩ, respectively. Subsequently, neutron
scattering experiments using the pulsed magnet system
was performed at NOBORU (BL10). Figure 6 shows theexample of the output waveform of the coil. The coilproduces 35 T with 6.6 kA at 18.1 kJ charged energy of
the capacitor of the power supply.
6. Humidity
In JFY2021, we developed a vapor generator thatallows us to control the D2O/H2O composition of the vapor continuously. The humidity generator was initiallydesigned for use in the small and wide-angle neutron

scattering instrument, TAIKAN (BL15), and neutron reflectometer, SHARAKU. We have constructed the gas ﬂow system based on two concepts: precise and stable humidity
generation and compositional changes due to gas mixing.
Key features of the system are two saturators and four mass
ﬂow controllers, which help generate D2O and H2O vapors
independently and quickly. The system makes possible
small-angle neutron scattering and neutron reflectivity
measurements under relative humidity of up to 85% withina temperature range of 25 °C to 85 °C.

Figure 4.	Remote monitoring system, used for high temperature experiment on SENJU.

Figure 5.	The coil that can generate a high pulsed magnetic
field of up to 35 T.

Figure 6.	Example of the output waveform of the coil.

R. Takahashi1, M. Ishikado2, Y. Yamauchi3, S. Ohira-Kawamura1,4, M. Nakamura3, H. Arima-Osonoi2, S. Takata1,4, Y. Su1, S. Zhang2,
T. Morikawa2, K. Ohuchi2, S. Yamauchi4,5, Y. Sakaguchi2, M. Watanabe1, and T. Oku1
1
Technology Development Section, Materials and Life Science Division, J-PARC Center; 2Neutron Science and Technology Center, CROSS;
3
NAT Corporation; 4Neutron Science Section, Materials and Life Science Division, J-PARC Center; 5Institute of Materials Structure Science,High Energy Accelerator Research Organization (KEK)128

MLF Annual Report 2021

Neutron Science

Development of Circuit Boards for Optical/Electrical
Conversion
1. Introduction
We are developing a two-dimensional neutron
detector system using helium-3 gas as a neutron converter [1, 2]. In the detector system, the electric charges
generated by the nuclear reaction between neutrons
and helium-3 are collected using a detector element.
The signals from the detector element are amplified,shaped, and discriminated, and then calculated as theincident position of the neutrons. Various electronic circuits are used in this signal processing, and the electronic circuit components used in signal processing boards
are usually discontinued after several years. A new signal
processing board was developed to support the discontinuation of the components. In the development process, the signal processing board was also upgraded toincrease signal processing speed, etc.
2. System design
Figure 1 shows a schematic of the two-dimensional
neutron detector system under development. The blue
frame in Fig. 1 depicts the developed signal processing
boards. The developed board determines the neutron
incident position from the X- and Y-axis signals output from the application specific integrated circuits(ASICs) used in the detector system. The optical signaltransmission system mounted on the board is used totransmit the neutron incident position to the data acquisition system. This system can transmit signals overlong distances of several kilometers by using optical fibers that are not affected by electrical noises. The developed board uses state-of-the-art field-programmablegate arrays (FPGAs) for digital signal processing, such

64ch
ASD-ASIC

20 m

64ch
ASD-ASIC

E/O
converter

(a)

(b)

T0 signal
from MLF

X,Y
signalsPosi�oncalcula�on
encoder

128 ch analog signals
64ch
ASD-ASIC

Data acquisi�on room

Dataacquisi�ondevice64ch
ASD-ASIC

2D-deetctor
element

Irradia�on area

128 ch analog signals

Pressure vessel

as determining the position of the incident neutrons.
The implemented FPGAs have a finer fabrication process and higher integration than the FPGAs currently inuse. As a result, the processing speed is more than twice
as fast and the number of logic elements is more than
2.5 times greater, while the power consumption of the
FPGA alone is reduced by 70%.
Figure 2 shows photographs of the present anddeveloped E/O converter boards. The present detector
system uses two boards for signal processing, one forthe x-axis and the other for the y-axis. The developedboard uses the latest FPGA to process 128 channels eachof x-axis and y-axis, for a total of 256 channels of signal
processing on a single board. In addition, the numberof optical fibers used is also reduced by using only one
board, although optical fibers are currently used forsignal transmission in each axis. The reduction in thenumber of boards enables the omission or shorteningof signal wiring, which is expected to reduce electricalOp�cal ﬁber

O/E
converter

Figure 1.	Schematic of a two-dimensional neutron detector
system. The blue frame depicts the developed signal processing boards.

Figure 2.	Photograph of (a) present and (b) developed
E/O converter boards.

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MLF Annual Report 2021

4. Summary
We developed a signal processing board with optical signal transmission. The developed boards work
well and can acquire two-dimensional neutron images
in real time with a counting rate of more than 1.27 MHz
and a pulse-pair resolution of less than 0.5 ns. This fast
response is an essential characteristic for the two-dimensional neutron detector system that measures highintensity pulsed neutrons.

50
40
30
20
0.41

10
0
0.2

0.6
0.8
Time interval (μs)

11.2Figure 3.	Counting losses of the developed board as a function of time interval of double pulses.
40

1.4
1.2
Measured signal

1
0.8

30

20

Counting loss

0.6
0.4

10
1.27

0.2
0

0

0.5

1
1.5
Frequency (MHz)20Figure 4.	Measured signals of developed board as a functionof the frequency of the continuous test pulse, andcalculated counting losses.

References[1] K. Toh et al., Nucl. Inst. and Meth. Phys. Res. A, 726
169 (2013).
[2] K. Toh et al., J. Instrum., 9 C11019 (2014).

K. Toh, T. Nakamura, and K. Sakasai
Neutron Instrumentation Section, Materials and Life Science Division, J-PARC Center

130

0.4

Counting loss (%)

3. Operation test
The evaluation tests of the developed board wereconducted using a test signal generation module and areal-time data display module. These modules were also
created specifically for the development of a gas-based
two-dimensional neutron detector system. The test signal generation module can generate detector-simulated
signals and is capable of outputting simulated signals at
any desired generation cycle and time interval.
The pulse pair resolution was measured by inputting two test-signal pulses into the developed board
with varying time intervals and counting the numberof pulses output from the board. The measured results
are shown in Fig. 3. The horizontal and vertical axes
show the time interval of the input double pulse andthe measured counting loss, respectively. It can be seenthat the counting loss increases from 0.41 μs as the timeinterval decreases. The developed board can discriminate input signals with time intervals over 0.41 μs.
Figure 4 shows the results of evaluating the counting rate capabilities by inputting periodic test-signal
pulses into the developed board with varying frequencies. The horizontal axis shows the frequency of the
input test signal, and the vertical axis shows the measured counts and counting losses. It can be seen that thecounting loss increases from 1.27 MHz as the frequency
increases. The developed board has linearity in counting
rate up to 1.27 MHz.

60

Counting loss (%)

noise and signal delays. Also, since the number of components used is reduced, reliability can be expected to
improve in terms of preventing failures at connections
and the increased durability of individual components.

Measured signal (Mcps)

Neutron ScienceMLF Annual Report 2021

Neutron Science

Activities for Remote Access at MLF
1. Introduction
At MLF, it has been in high demand a way for remote
access from outside of the J-PARC site for both users andstaffs in order to control the experimental instruments
devices and to monitor the status. To do measurement
using neutrons at MLF, internal staffs and users must
perform many tasks nearby a beamline instrument in
the experimental hall, for example sample preparations, decisions concerning users’ experimental conditions and operation of instruments devices suitable forthe measurement. After a measurement starts with therequired conditions, users and staffs start monitoring
the progress in experiments to avoid accidents and to
decide the next condition for their scientific purpose.
Monitoring from outside of the experimental hall, especially, is in high demand because users and staffs neednot stay long time nearby instruments during the measuring process.
Our MLF computing group provided IROHA2 which
is a software system to control various devices installed
in instruments and to implement step-by-step device controls on a given schedule using web interface
through a network [1]. Internal staffs can use the IROHA2
system to watch and control at their office room far fromthe experimental hall. However, for security issues, it is
not easy to access IROHA2 directly on the internal servers in the J-PARC site through the internet. Therefore,
we built an additional server on the DMZ area of J-PARC

LAN (JLAN) and we added new functions to IROHA2 to
put only status information into the server for monitoring from outside. This remote monitoring system has
been working well and now has provided to many staffs
a routine access to IROHA2.
On the other hand, data handling is another issue.
Recently, the amount of data produced from beamlines
at MLF has become much larger with the increasing
neutron source intensity and the expanding number ofmeasurements with various conditions. It is difficult forusers to handle such huge data, for example to take itback to users’ laboratory to analyze them on their own
computing resource. Though many users want to utilize
the computing resources at MLF, which are larger thanusers’ ones, for data handling, our computing group
could not cope with their overwhelming demands.
2. Design
The recent COVID-19 pandemic situation, however,strongly focused our attention on these issues. To avoid
crowds near the beamlines and to carry out experiments
which users could not attend due to the COVID-19 situation, the remote access methods are required much
more than before. The MLF computing group, therefore, has decided to produce a guideline and a model
system for methods to control instrument devices andto analyze measured data from the internet, shown in
Fig. 1. Almost all instrument devices and data processing

Figure 1.	The proposed model for remote access using SSL-VPN and virtual
desktop system.

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servers are placed on JLAN, which has strong security
protection against unauthorized access. To gain accessto these servers from the internet, users and staffs must
connect to servers inside JLAN through secure path bymeans of SSL-VPN (JLAN SSL-VPN), which is managed
by the J-PARC Information System section. If users execute their own experiment from the internet in realtime, staffs must take care of various security issues, forexample, security incidents in the information systemand handling mechanical devices. The MLF, therefore,
prepares some check sheets for incidents and requires
users to confirm them. However, there was no properuse of these full remote experiments this year because
it is not easy for staffs to leave a full control of the instruments to users.
After all, the MLF computing group has constructed
and serviced for users only the remote desktop environment system to process and analyze measured data, as
shown in Fig. 2, and the automated processing and synchronization of data with users.

3. Developments
Users at some beamlines need desktop environments for processing measured data. They can install
desktop environments for processing by themselves,
but installations of those environments are complicated for most users. Additionally, the environments
often require updating programs and maintaining
system modules. These tasks, unrelated to the processing and analysis, often make users feel uncomfortable.
Therefore, we decided to construct simpler desktop environments, which can be used easily for processing byusers. New environments will be installed on JLAN andusers can gain access to them via JLAN SSL-VPN. On theother hand, we must take care of the network security.
JLAN is the main network in J-PARC. It is designed not
only for office use but also for instruments control, so
unlimited access to all networks cannot be permitted.
For that reason, we adopted the NoMachine Cloud Server(Cloud Server) system [2]. Environments which are usedby users are isolated from JLAN. With this configuration,

Figure 2.	The structure of the remote desktop environment system fordata processing services for users.

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MLF Annual Report 2021

we can control user activities on the network. In the system, Cloud Server works as a portal for users, and the users connect to the NoMachine Workstation (Workstation)systems through the Cloud Server (Fig. 3). Desktop environments for users have been installed on PCs that havealready Workstation installed. The user connects to the
Cloud Server and initially is required to provide authentication. After the authentication is verified, the user
can select authorized desktop environments only andconnect to one of them. The user processes the measured data on the selected environment, which has been
prepared by the MLF staff. We have decided to achieve
this scheme with virtualization, and we have prepareda virtualization host machine and virtual machines for
the NoMachine systems. In addition, users can use the
MLF central storage system, named ACE storage, so they
process the data seamlessly with the MLF beamlines.
Additionally, we introduced another way for processing. In some situations, automatic data processing
is suitable for remote measurements. This scheme is

Neutron Science

very simple, as shown in Fig. 4. At the beamline, data
is processed by each measurement automatically andthe results are copied to the location which is boundto Google Drive. Google Drive synchronizes files among
related folders on different systems. As a result, the files
in the beamline folder will be copied to the user’s PC.
If distant users participate in the experiment, all folders will be synchronized in the same way. This scheme
is more useful for routine processing, but the remote
desktop is better when using manual processing. This
scheme has resolved the sharing data problem between
beamline and users’ place. It needs to be solved to sendmeasured data and/or processed data to users’ working
environments at their own places.
4. Results and future plans
NoMachine is a lightweight remote desktop.
Unfortunately, JLAN SSL-VPN is too slow to use the remote desktop stably. This is the most critical problem.
Connecting to JLAN with SSL-VPN is very complicated. It

Figure 3.	The technical structure of the remote desktop environment system for data processing using NoMachine.

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MLF Annual Report 2021

Figure 4.	The scheme of the process to deliver processed data
to users.

has been pointed out that the connection method is inconvenient and unstable. So, we must improve the network connection stability as soon as possible. However,these network equipment problems are difficult to solve
immediately for procurement and configuration work.
Now, we consider the option to migrate the system tocloud platforms, for example, Amazon Web Services(AWS), Google Cloud Platform (GCP) and so on. We havesome accounting procedural issues, but we think it istechnically viable.
In this implementation, we set up the specified
environment for each beamline. But independent environment is inefficient with resource usage and human workload. We will investigate the environments
on each beamline and will develop a common environment as much as possible. In the common environment, analysis programs will be specified by beamline.
On the other hand, data transfer is a problem of remoteanalysis. We have developed a simple data transfer with
Google Drive as described. Data synchronization, such

as Google Drive, may be one of the solutions. We will
investigate and improve the synchronization ways.
5. Summary
We proposed a schematic model for remote access
at MLF and produced the remote desktop environment
system for data processing and analysis. We’ve alreadystarted the remote desktop service to users on a small
scale at several beamlines. However, there are many
problems with the access speed via JLAN SSL-VPN, system operations by us and so on. In order to make oursystem’s operations more efficient for users, for example
using cloud services, we will continue with the improvements in the remote access environment.
References[1] T. Nakatani, et al., JPS Conference Proceedings, 8,036013, 2015.
[2] https://www.nomachine.com

Y. Inamura1 and N. Okazaki2
Neutron Science Section, Materials and Life Science Division, J-PARC Center; 2Neutron Science and Technology Center, CROSS

1

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Muon ScienceMuon Science

MLF Annual Report 2021

Muon Section Overview
1.	Commenced production of the third muon production target
In response to the remarks by the Muon Advisory
Committee (MAC) and the International Advisory
Committee (IAC) of J-PARC, the Muon Section received
a budget for the production of a new muon target in
FY2021. This is to reduce the current risk of operating
without a spare target as a result of the unexpected failure of target Unit #1 in FY 2019, which was replaced witha spare (Unit #2). The project will be carried out over a
period of two years, with the target storage container
to be fabricated in the first year and the rotating target
body in the second year. This is because it is necessary toreexamine the applicability of the Hot Isostatic Pressing(HIP) technique in advance, which is the key to target
fabrication.
In the meantime, the rotating feeder unit was replaced as part of the maintenance in the summer shutdown period. It is recommended to replace it every two
years, considering the wear and tear on the bearings.
This was the first time since the rotating target itself
has been replaced, and the work was carried out after
careful preparation (see Fig. 1). However, a turbulence inthe motor torque was confirmed during the test operation after the work, and it was presumed to have beencaused by misalignment of the joint connecting the target rotation shaft and the drive shaft on the vacuum side.
To resolve this problem, another adjustment was
attempted near the end of the maintenance period.
However, subsequent beam operations revealed thatthe situation had not improved, suggesting that the
a)

b)

c)

connection accuracy between the rotating shaft andmotor shaft was inadequate due to manual work.
Therefore, it was decided to replace the flexible joint forthe connection with one that has a higher tolerance forshaft misalignment during the next maintenance period, and the model selection and testing proceeded.
2. Construction of the H-Line
H-line is a new beamline under construction since
FY2012 in Experimental Hall No.1 of the MLF building.
It is a general-purpose beamline that can deliver both
positive and negative muons and it has branches to two
experimental areas named H1 and H2. The designed
surface muon flux reaches 108 muons/s with a proton beam power of 1 MW owing to a large acceptance(108 mSr) capture solenoid and other beamline magnets
with a large aperture.
As for the beamline to H1, the installation of coolingwater piping and power cables progressed during thesummer shutdown period, and was almost completed
by the end of November. In addition, the review of facility modifications, including those for MUSE, by the
Nuclear Regulation Authority (NRA), which had been
delayed due to COVID-19 during this period, was finallycompleted and operation permission was granted. After
prior approvals from JAEA and the surrounding municipalities, the beam commissioning started in January
2022. During beam commissioning, a large positron/
electron background existed because the DC separator
had not yet been installed. Although this made beamcommissioning difficult, the commissioning team was
a)

d)
b)

Figure 1.	
Rotating muon target (a) and its rotation feedthrough with a flexible joint (b). A snapshot of thetarget maintenance work (c) which was conducted within a greenhouse setup in the M2 area (d).

136

400mm

Figure 2.	The H1-commissioning team headed by T. Yamazaki(a), and the muon beam profile measured by an imaging plate at the exit to the H1 area (b).

MLF Annual Report 2021

able to measure the beam intensity, profile, and momentum of the surface muons (see Fig. 2). The beam
intensity of negative muons at several momenta wasalso measured.
3. Renovation of the beam kicker system on the S-Line
The S line is designed and built mainly for surface
muon beams, and the beam kicker system allows muon
experiments to be performed simultaneously in twoareas, S1 and S2, by splitting a double pulse into twosingle pulses. The stable operation of the kicker device
is very important as S2 begins operation in 2021.
The kicker device has encountered several problems
since the start of the S-Line operation in 2017. One ofthese is the failure of the MARX board, which continues
to occur several times a year. Since the failure was foundto be caused by a certain component, the replacementof all 384 components on the MARX board was carriedout during the summer shutdown period before the fullscale simultaneous operation of the S1 and S2 areas began.
Drastic measures were also taken during the summer shutdown period to address another issue: the location of the kicker power supply. The kicker power supply
was installed inside the concrete shielding of the S-Lineto reduce the potential impact of noise generated by
the electric field kicker on the experimental equipment.
Therefore, the concrete shield had to be opened and replaced every time a MARX board failed, making the work
extensive and difficult. To resolve this issue, the kicker
power supply unit was relocated to the fourth floor of
the power supply yard to facilitate access during repairs(see Fig. 3). Upon the completion of the relocation work,
Inside the shield block

4th floor of the Exp. Hall

Figure 3.	A schematic illustration of the beam kicker systembefore and after the relocation of the power supply.

Muon Science

the entire system was confirmed to be operational under the required specifications. Since then, although
the MARX board failed due to a cause other than the replaced component, operation could be resumed withina maximum of half a day after detecting the failure, asignificant improvement over the previous situation inwhich it took up to seven days to resume operation.
4. Laser system for Ultra-slow muon
Ultra-low velocity muons can be produced by resonant photoionization of thermal muonium from hot
W-foil targets. In particular, a high-energy pulsed coherent Lyman-α light source is one of the most criticalelements for efficient generation of ultra-low-velocity
muons. Due to its high photon energy, the vacuum ultraviolet light causes degradation of optical materials
over time. In addition, photochemical reactions that occur between vacuum ultraviolet light and residual gases(mainly hydrogen and carbon) that cannot be evacuatedby turbo molecular pumps in vacuum cause degradation of the performance of the Lyman-α steering mirror.
Degradation of the optics leads to a loss of ultra-slow
muon yield and beam downtime for optics replacement.
In addition, the surface of the mirror becomes noticeably cloudy when the same area is continuously irradiated with Lyman-α light for an extended period of time.
This year, we introduced a drive mechanism thatchanges the laser reflection position of the mirrors for
vacuum ultraviolet light and restores the reflectivity ofthe two mirrors. This device adds a mirror displacement
function to the mirror mounts that can adjust the horizontal angle and vertical tilt of the mirrors. The mirror
mount located upstream has a rotation stage to rotate
a 50 mm φ circular mirror and a linear-motion stage(30 mm stroke). The mirror mount on the downstreamside uses a 50 mm square cylindrical mirror, which allows horizontal and vertical motion. These stages havebuilt-in encoders that record the movement history of
the mirror positions, allowing the laser reflective surface
to be set to the unirradiated area when the reflectivity ofthe mirror decreases. The new mirror steering and displacement device enables the mirror irradiation position
to be adjusted by remote control without opening thevacuum chamber to the atmosphere.

R. Kadono1,2, K. Shimomura1,2, A. Koda1,2, P. Strasser1,2, T. Yamazaki1,2, S. Kanda1,2, S. Takeshita1,2, I. Umegaki1,2, Y. Ikedo1,2,
Y. Kobayashi1,2, J. Nakamura1,2, T. Yuasa1,2, N. Kawamura1,2, Y. Oishi1,2, Y. Nagatani1,2, S. Matoba1,2, S. Nishimura1,2, S. K. Dey1,2,
W. Higemoto2,3, and T. U. Ito2,3
1
Institute of Materials Structure Science, KEK; 2Muon Science Section, Materials and Life Science Division, J-PARC Center; 3Advanced
Science Research Center, JAEA

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MLF Annual Report 2021

Present Status of the Muon-Beam Source
The muon production target and the frontend partof each muon beamline are located in the M2 tunnel,
downstream of the primary beamline, as shown in Fig. 1.
This area is under a high radiation field due to the secondary particles generated by the muon target, and its
operation is a key to the stable and safe operation of thewhole MLF facility containing not only MUSE but also
JSNS. The activation effect in the devices and radioisotopes, especially tritium, becomes more serious withevery passing year. We are accumulating the know-how
for the full-year 1 MW operation.
1 Muon production target
In FY2019, the rotating target was replaced with a
new one due to trouble in the 1st rotating target. The 2nd
target had been operated without any essential troubles
before the summer maintenance period in 2021.
1.1 The 3rd target preparation
The replacement of the target was unexpected andwe had to use the spare one as the 2nd. Thus, preparing
the new spare target became an urgent issue and a toppriority task for the muon section. In FY2021, we started
the preparation work under a several-year plan. If thepresent target fails, we have to stop the muon facility
operations. Thus, MAC, the Muon Advisory Committee,
strongly recommended preparing the 3rd target as early as possible. To answer this, owing to the budgetary
support of the J-PARC center and IMSS, the fabrication
schedule was brought forward, and the 3rd target will beready by the end of the next fiscal year. In FY2021, test
S

H

D
Exp. Hall #2

Figure 1.	The horizontal (upper) and the vertical sectionalview (lower) of the M2 tunnel. The proton beam istransported through the tunnel from the left side to
the right side of the neutron target.

138

1.2 Replacement of the rotation feed-thru
The rotating shaft of the target assembly is connected to the motor out of the beamline vacuum throughthe rotation feed-thru. The lifetime of the feed-thru is
determined by the total number of rotations and it has
to be replaced every two years. Thus, we planned thereplacement work for the maintenance period of 2021
as annual work. The replacement work created a highrisk with the possibility of internal exposure due to thetritium from the muon target. The work was well prepared according to the safety review and conductedsmoothly in the summer of 2021. However, after the
replacement, we found turbulence in the motor torquein the off-beam rotating test. Finally, the reason for the
turbulence was determined to be due to the misalignment of the feed-thru, and we re-adjusted it near theend of the maintenance period. However, these works
did not solve the problem and the rotating torque wasstill unstable, even in the beam operation. The beam
stoppages of the MLF occurred by the interlocking of
the motor torque a few times, and thus we changed theinterlock policy slightly to avoid disturbing the MLF op-

Exp. Hall #1

Muon targetU

pieces of cooling-water pipes buried in the target assembly by hot isostatic pressing were fabricated (Fig. 2). The
same parts were used in the 1st and the 2nd target, but thedetailed knowledge had been lost due to the retirementof the artisan employed by the manufacturer. In FY2022,
the main body of the target assembly will be fabricated.
The details are reported separately [1].

Figure 2.	Test pieces of cooling water pipes to be buried in
the target assembly.

eration. The temporary value of the interlock still has asafety margin, but this is not a healthy situation.
The rotation feed-thru is connected with the rotating shaft of the target with the coupling. The allowableeccentricity of the center axes between the feed-thru
and the shaft is 0.2 mm, and this high-level accuracy
becomes hard to achieve in the maintenance in the M2
tunnel because the work has to wear rad-hard equipment such as an airline mask and vinyl anorak suit toprevent internal exposure by tritium.

MLF Annual Report 2021

We prepared a new coupling whose allowable eccentricity is sufficiently high and will replace the present
one with it in the maintenance period of 2022.
We also consider developing a long-lived motor
feed-thru. The lifetime of the motor feed-thru is determined by the bearing, and we will be able to replace itwith a reliable one even in the high radiation field.
The details are reported separately [1, 2].
1.3 Collaboration with the PSI
At the beginning of the MLF operation in 2008, we
adopted the fixed target [3]: the proton beams were irradiated onto the center of the 2 cm thick graphite disk
surrounded by a water-cooled frame. However, the fixed
target was expected to break within one year due to theaccumulated radiation damage around the center of the
disk. Thus, the rotating target was developed based on
the original one developed at the Paul Scherrer Institute(PSI) in Switzerland. But it was known that the bearings
that supported the rotating shaft had a short lifetimeand could cause malfunction within a short period, lessthan a year.
We developed the rotating target for MLF J-PARC
with bearings using radiation hard tungsten disulfide
solid lubricant (Fig. 3). This J-PARC version of the rotating target achieved stable continuous operation for five
years from 2014 to 2019. The 1st rotating target was unexpectedly replaced due to the trouble in the coupling
connecting the motor feed-thru and not in the bearing.
Thus, the lifetime of the bearing could be longer than
five years. The 2nd rotating target succeeded in continuously receiving a 0.83 MW beam up to the present while
the beam intensity has gradually increased. This solidlubricant bearing was also adopted at the PSI and had
achieved stable continuous operation over a period of
one year, the best result after a long period of several
bearing failures at the PSI.
We hope to keep this relationship with the PSI not
only for the target but also for other things like thebeamline, experimental techniques, and so on.
1.4 Long-term storage of spent targets
The original plan to store the spent target was madefor the fixed target whose lifetime was less than a year.
Thus, dozens of the spent targets were expected to be
stored by reducing their volumes. The scenario of theMuon Science

Figure 3.	Solid-lubricant
bearing used in the
MLF J-PARC.

volume reduction was constructed to cut the target
rod by a dedicated device in the hot cell. However, thespent target is expected to be highly activated and suchwork will pose a high risk. We have completed a rotating target that has a much longer lifetime and does notneed high volume reduction. Therefore, we will start toreconsider the long-term storage of the spent targets.
2 Secondary beamlines
The frontend magnets of all the secondary beamlines are placed surrounding the target chamber.
Historically, the D-line magnets and the S-line ones wereplaced at the start of the MLF operation in 2008. Then,the U-line magnets, US1 and US2, were facilitated in2009. And lastly, the frontend magnets in the H line, HS1
and HB1, were installed in 2012 before the activation in
the working area became serious. Since then, the H line
construction has been continued and finally completed
in FY2021 up to the H1 area [4].
As well as the U line, the H line uses a large aperture solenoid for the frontend magnet to increase theacceptance of the muon beam. The leakage field of thesolenoid on the proton beam line is not negligible andthe BL product is expected to reach about 0.01 Tm. The
proton beam is kicked by about 1 mrad to the verticaldirection at the maximum excitation of HS1. This drift iscompensated by the steering magnets located downstream of the muon target. The auto-feedback programthat reads the current of HS1 and sets the current of thesteering magnets has been developed by extending the existing system for the U line. The program is developed andoperated by the 3NBT group of the neutron source section.
References[1] S. Matoba et al., ibid.
[2] Y. Kobayashi et al., ibid.
[3] S. Makimura et al., Proc. of Sci. 369 (2020) 124.
[4] T. Yamazaki et al., ibid.

N. Kawamura1,2, S. Matoba1,2, Y. Kobayashi1,2, and A. Koda1,2
Muon Science Section, Materials and Life Science Division, J-PARC; 2Muon Science Laboratory, High Energy Accelerator Research
Organization (KEK)1139Muon Science

MLF Annual Report 2021

Beam Commissioning at D1/2 Areas
1. Introduction
The D line of MLF MUSE has a long superconducting solenoid, which can provide positive and negative
decay muons from a few MeV/c to 120 MeV/c in addition
to surface muons. The primary proton beam energy of
the MLF is as high as 3 GeV, resulting in a high negative
muon yield. In particular, thanks to the recent increase
in beam power, the world’s highest intensity negative
muon beams are available. Using this high-intensity
negative muon beam, various experimental applications
have been developed, such as nondestructive elemental
analysis using negative muon characteristic X-rays andnegative muon spin rotation/relaxation. In this report,
we report the current status of the negative muon beamcommissioning at the D line.
In experimental area D1, negative muon spin relaxation measurements can be performed using polarized high intensity negative muons. Recently, several
results have been obtained by the negative muon spin
relaxation method. However, further commissioning isrequired to perform more precise experiments with avariety of samples. Here we report on the tuning of asingle bunch beam using a kicker system.
2. Kicker system and its operation at the D line
The MLF provides double bunch beams with a 25 Hz
period. Each bunch has a width of 100 ns and a bunch
spacing of 600 ns. The D line has a kicker system at thebranch section to the D1 and D2 areas, which can be
operated to provide single bunch beams (and, with appropriate adjustments, single bunch beams to both D1and D2 areas simultaneously).
The branch consists of two switchyard magnets(DSY1 and DSY2, the so-called bending magnets), twokicker magnets (DKKR1 and DKKR2), and septum magnets (DSPTM1 and DSPTM2) that direct the muon beam
toward areas D1 and D2 (Fig. 1).
As an example, we explain how to operate the system for negative muons. If the kicker is not excited, thetrajectory of the negative muon beam is slightly bent toward the D2 by the DSY1 and 2, directed to the entranceof the DSPTM2, and further guided by DSPTM2 toward
the D2 area properly (Fig. 1(a), here we call this a mainstream beam). When the second bunch passes through
DKKR1 and 2, the kicker is excited with the appropriate voltage and timing, and only the second bunch isbent toward the DSPTM1 and directed to the D1 area
(Fig. 1(b), here we call this a tributary beam). Since DKKR
140

is unipolar, the kicker must be operated against the double bunch beam fed to the D2 area (and vice versa for
positive muons).
3. Tuning of delay timing for the kicker trigger
In order to operate the kicker accurately, the delay
timing of the trigger that excites the kicker must be adjusted to match the beam of the 2nd (or 1st) bunch. To
make this adjustment, two detectors consisting of a 5mm thick 75 mm square scintillator and a photomultiplier tube were installed in the D1 area (Fig. 2). For a muon

Figure 1.	Schematic view of the branch section with the kicker system and its operation (a) without and (b) withkicker excitation for negative muons.

Figure 2. Detector configuration at the D1 area.

MLF Annual Report 2021

beam with a momentum of about 30 MeV/c, all muonsstop at the scintillator of the detector installed upstream
and cannot pass through. Therefore, the downstream
detector can only detect signals from electrons/positrons. The signals from each detector were input to acharge-to-digital converter (QDC), and the integrated
intensity was obtained.
Figure 3(a) shows the bunch structure, timing of themuon beam, and kicker excitation waveform. Figure 3(b)shows the timing of the gate signal used to observe
each signal. Figures 3(c) to (f ) show the simulation results of the positive and negative muon beam intensity
observed in the D1 area as a function of the delay time
for the kicker trigger. The simulations were obtained by
performing convolution integration of the kicker waveform and muon (and electron/positron) pulses.
In the case of positive muons, the mainstream is thebeam guided to the D1 area without kicker operation,and the tributary beam is the beam kicked to the D2
area by the kicker. Therefore, the signal in the D1 areachanges as shown in Fig. 3(c) (1st bunch) and Fig. 3(d)(2nd bunch). On the other hand, in the case of a negative muon, the mainstream is the beam led to the D2
area without kicker operation, and the tributary beam isthe beam kicked to D1. Since the beam intensity is notobserved at D1 on the tributary side unless the beamis kicked, the signal changes as shown in Fig. 3(e) (1stbunch) and Fig. 3(f ) (2nd bunch).

Figure 3.	
Simulated intensity of positive/negative muon
signal observed at the D1 area with DKKR excited.

Muon Science

The observed delay time dependence of the signal
intensities in each bunch of the surface (positive) muons (Fig. 4(P-a) and (P-b)) and decay (negative) muons of
30 MeV/c (Fig. 4(N-a) and (N-b)) at the D1 area is shown.
Also, the shown values in the figure are the arrival timesof the respective beams (versus the delay time) obtained from the derivative curves of the signal intensity.
For the positive muon signals in Figs. 4(P-a) and4(P-b), the obtained data correspond to the signal after
1 μs in the Figs. 3(c) and 3(d). In Fig. 4(P-b) which shows
the intensity of the 2nd bunch, there is an increase in thepositron signal intensity around the time when the 1st
bunch muon arrives (100.1 μs), but this is a backgroundsignal because decaying positrons from the positive
muon that stopped in the upstream muon detector
were injected into the downstream positron detector.
From this result, it is clear that the optimal delay timing
for triggering is approximately 100.28 μs in order to excite the kicker at the timing for delivering the complete
1st bunch and kicking the 2nd bunch completely.

Figure 4.	Observed intensities at D1 under operation of
DKKR. (P-a) surface (positive) muon gated at 1st
bunch, (P-b) 2nd bunch. (N-a) Decay (negative)
muon gated at 1st bunch, (N-b) 2nd bunch.

141Muon Science

MLF Annual Report 2021

Next, measurements were performed for negative
muons, and the results are shown in Figs. 4(N-a) and4(N-b). As with the positive muon case, an increase
due to the signal of decay electrons stopping at the
upstream muon detector (and injecting into the downstream electron detector) is observed around 99.8 μs in
the electron detector at the 2nd bunch. For negative
muons, the optimum condition is that only the 2nd
bunch is delivered to the D1 area. The figure showsthat a kicker trigger delay time of approximately 100.1
μs is optimal. However, these delay times may varydepending on the accelerator operating conditions, so
adjustments should be made on a case-by-case basis.
4. Summary
We reported the tuning method to obtain a single bunch
beam for the D1 area by setting the kicker trigger delay appropriately for the double bunch beam provided by the MLF,
and the results. The tuning results showed that 100.28 μs wasappropriate for the surface (positive) muon and 100.1 μs forthe decay (negative) muon.

S. Takeshita1,2, P. Strasser1,2, A. Koda1,2, W. Higemoto2,3, I. Umegaki1,2, M. Tampo1,2, S. Doiuchi1,2, A. Hashimoto1,2, N. Kawamura1,2,
and K. Shimomura1,2
1
Muon Science Laboratory, Institute of Materials Structure Science, KEK; 2Muon Science Section, Materials and Life Science Division,
J-PARC Center; 3Advanced Science Research Center, Sector of Nuclear Science Research, JAEA

142

MLF Annual Report 2021

Muon Science

Current Status of µSR Experiment at D1
At the D-line, muons are delivered to the D1 and/or
the D2. At the D1-area, the µSR spectrometer is installed
as a main and fixed instrument. Since high momentum
muon, surface muon, and negatively charged muon
are available at the D1, all type of µSR measurements,
except for the ultra-slow µSR, can be carried out. In particular, unique sample environments, such as very low
temperature, high pressure etc. were possible to carryout only at the D1. Figure 1 shows the µSR spectrometerwith the dilution refrigerator and the fly-past chamber.
Here, we report recent accuracy improvement of theµSR measurement.
Positron energy selected µSR at D1
The positive muon decays into positron and twoneutrinos with a mean lifetime of 2.197µs. This positronis emitted in a certain direction with a certain energy.
As shown in Fig. 2, the asymmetry factor depends on

the positron energy and the lower energy positron possesses a lower asymmetry factor. Therefore, by cutting
low-energy positrons, we can obtain higher asymmetry
factor as total.
The total accuracy depends on the number of counting positron N and total asymmetry A. To cut the low-energy positron, a copper plate was placed in front of thepositron counters as absorber, and we investigated the
optimal thickness for the copper plate. Figure 3 shows
the copper plate mounted at the D1 spectrometer. Asa beam window, 60 mm in diameter hole was openedat the copper plate. As a sample, another copper platewith a thickness of 0.5 mm was placed at the center ofthe spectrometer. We used single pulse of 4 MeV surface
muon and muon was roughly stopped at the center ofthe sample plate in depth. We applied 20G of transverse
field to measure the asymmetry factor. As figure of merit(FOM), we defined NA2 and FOM maximization thickness

Figure 1.	µSR spectrometer with the dilution refrigerator andthe fly-past chamber at the D1.

Figure 2.	Positron/electron energy dependence of energy
spectrum (red) and asymmetry factor (blue).

Figure 3.	D1 µSR spectrometer with the copper plate which is located in front of
the positron detector.

143

Muon Science

MLF Annual Report 2021of the copper plate was investigated.
Figure 4 (a) shows the copper plate thickness dependence on the asymmetry factor. The asymmetry
factor gradually increases with increasing the copper
plate thickness and becomes ~0.29 with a copper plate
thickness of 6 mm. Meanwhile, the counting rate is also
dependent on the copper plate thickness and gradually decreases with increasing thickness, as shown in
Fig.4(b). At 6 mm, the count rate roughly becomes halfof that without copper plate.
FOM is shown in Fig. 4 (c). FOM reaches a maximum
at 3 mm thickness. This fact indicates that the most efficient measurement can be carried out with a copper plate of 3 mm thickness. Of course, this value also
depends on the thickness and density of the sample,
sample holder and chamber. We note that this situationmust be the same for the negative muon.
In summary, to maximize the µSR accuracy, we putcopper plate and found that 3 mm thickness of the copper was the best value at D1.

Figure 4.	Copper plate thickness dependence on (a) asymmetry, (b) count per pulse and (c) figure of merit.

W. Higemoto1,2,3 and S. Nishimiura2,4
Advanced Science Research Center, Japan Atomic Energy Agency; 2Muon Section, Materials and Life Science Facility Division, J-PARC
Center; 3Department of Physics, Tokyo Institute of Technology; 4Muon Science Laboratory, Institute of Materials Structure Science, HighEnergy Accelerator Research Organization (KEK)1

144

MLF Annual Report 2021

Muon Science

Development of D2 (Muonic X-ray Element Analysis)
Instrument and Sample Environment
The D2 experimental area is actively used for variable experiments with positive and negative decay muons. This is because the D2 experimental area basicallyis a space of about 4 m × 4.5 m, allowing users to bringin their own equipment or chambers needed to realize their experiments. This has led to the publication ofremarkable results in several fundamental physics experiments in FY2021 [1–4]. In addition, the soft errors
induced in semiconductors by muon irradiation werestudied, and their characteristics were clarified in comparison with those of neutrons [5]. This work is expected
to contribute to the construction of effective evaluationand countermeasure technologies against soft errors
caused by environmental radiation, and to lead to the creation of safe, secure, and reliable semiconductor devices.
On the other hand, in recent years, elemental analysis with muonic x-rays has been one of the most popular experiments at D2 experimental area. This kind ofexperiments requires a suitable sample chamber andgermanium (Ge) semiconductor detectors. In fact, a
lot of elemental analysis with muonic x-ray has been
conducted on archaeological objects with historicaland scientific value [6], meteorites [7, 8], and lithiumion batteries [9] with remarkable results. Furthermore,
it is desired to obtain fine data within shorter time inorder to perform effectively larger numbers of interesting research programs in limited beam time. Therefore,
the development of the sample environment and the
addition of detectors are essential to this background.
The major progress of the D2 experimental area

in FY2021 was the modification of the sample chamber for elemental analysis muonic x-ray, the so-called
hemispherical chamber, to make up to 10 ports available for detectors (Fig. 1). There are three types of ports
with different diameters: φ76.3 mm (6 ports), φ165.2 mm(2 ports), and φ60.5 mm (2 ports). Different detectors canbe installed according to the size of the end cap of eachdetector (Table 1). In particular, ports 1-5 can be usedwith a Ge detector for low energy (LEGe), and ports 6-7
can be equipped with a Ge detector with a thicker end
cap (MGe), which are for detecting muonic x-rays withenergies below 300 keV. While ports 8-9 can fit into a
multi-pixel detector, LEGe can also be mounted using a
conversion flange to match the diameter size (Fig. 2). In
addition, there are two upper ports 10-11 to install a decay counter or a smaller detector (e.g., a non-refrigerant
detector requiring no liquid N2 tank such as a silicon drift
detector SDD).
The hemispheric chamber was modified so that seven Ge semiconductor detectors could be mounted, andvarious elemental analysis experiments were conductedusing these detectors in FY2021. As an example, the following elemental analysis experiments were conductedin FY2021:[2021B0321] Detection of metallic Li deposition in alithium-ion battery with muonic x-rays[2021B0356] Evaluation of activation by negative muons[2014MS01] Elemental analysis of inkstick on inkstone
surface[2021MS01] Elemental analysis of gold coins from theTable 1.	Diameter of the ports (additional flange) and detectors frequently used at each port.
Port
1-5
6-7
8-9
10-11

Diameter (flange)
76.3 (20) mm
76.3 (25) mm
165.2 mm60.5 mm

Main purpose
LEGe
MGe
Multi-pixel Ge detectors
Decay counter, SDD

Figure 1.	Illustration of Hemispheric chamber with seven Ge
semiconductor detectors and multi-pixel Ge detectors on the left and right sides.

145

Muon Science

MLF Annual Report 2021

Shuri Castle in Okinawa
Other than elemental analysis, the hemisphericalchamber was also used for experiments, such as muontransmission imaging and muon fusion.
Lastly, it is noted that elemental analysis was performed on the return samples from Ryugu by Hayabusa
2 program at D2 experimental area [10], although their
special sample chamber covered with copper was usedinstead of the hemispherical chamber.
In FY2021, three new low-energy semiconductor Ge
detectors (LEGe) have become ready for experiments.
Next year, we expect to have further fruitful research
programs in elemental analysis using muonic x-rays.

Figure 2.	Photo of Hemispheric chamber in the view fromdownstream of the beam. Gold coins are set at asample position. Ge semiconductor detectors andmulti-pixel detectors are equipped at Port 1 - 7, andPort 8 - 9, respectively. Ports 10 - 11 can be used for
decay counters and other detectors.

Figure 3.	(a) Angles at each port in the Hemispheric chamber.
(b) When the direction of the beam (from upstream
to down-stream) is defined as z-axis, ф and θ arean angle from the z-axis in the horizontal plane (xyplane) and an elevation angle from vertical axis (y).

I. Umegaki, M. Tampo, Y. Miyake
Muon Science Laboratory, Institute of Materials Structure Science, KEK

146

Acknowledgments
The development of the sample environment that
we showed here was conducted as a part of “integration of arts and sciences” research program promotedby the KEK IMSS MSL. It was also supported by the JSPS
Grant-in-Aid for Scientific Research on Innovative Areas"Toward new frontiers: Encounter and synergy of stateof-the-art astronomical detectors and exotic quantum beams”. The authors appreciate the cooperationof Mr. Shogo Doiuchi, Dr. Akiko Hashimoto, Mr. Yudai
Ishikake, and other members of the Negative Muon
Group. The design and production of the hemisphericalchamber and the detector adding were managed withgreat diligence by Dr. Tampo.
References[1] T. Okumura et al., Phys. Rev. Lett. 127, 053001(2021).
[2] S. Nishimura et al., Physical Review A, 104, L020801(2021).
[3] K. Okutsu et al., Fusion Engineering and Design, 170,
112712 (2021).
[4] T. Yamashita et al., Fusion Engineering and Design,
169, 112580 (2021).
[5] T. Kato et al., IEEE Transactions on Nuclear Science68, 7, 1436-1444 (2021).
[6] K. Shimada-Takaura et al., Journal of Natural
Medicines, 75(3), 532-539 (2021).
[7] K. Terada et al., Scientific Reports, 9, 1, (2019).
[8] K. Terada et al., Scientific Reports, 7, 15478 (2017).
[9] I. Umegaki et al., Analytical Chemistry, 92, 81928200 (2020).
[10] http://j-parc.jp/c/topics/2021/07/15000718.html

MLF Annual Report 2021

Muon Science

Beamline Magnets and Power Supplies
Replacement of DB2 Coils and Status of Updating the MPS program
for the Muon Target
1. Introduction
The bending magnet DB2 is installed in the decay
muon beamline (D-line) at the Materials and Life Science
Facility (MLF) of J-PARC. The existing DB2 is a dipole
magnet, and over 40 years have passed since its production. Therefore, we planned to exchange the degradedcoils with new ones within three years. In 2021, the final
year of the three-year plan [1, 2], we exchanged the coils
and measured the magnetic field with a Hall probe tocompare the magnetic field measurements before andafter the coil replacement.
Furthermore, in the MLF operation in January 2022,
it was discovered that the torque in the rotation mechanism of the muon target was not constant, which was a
problem. The MPS program for the muon target needed to be updated because of a hunting phenomenon
that occurred due to the abnormal rotation torque inthe muon target motor, resulting in a malfunction in
the rotation indicator of the muon target display in the
MLF control room. It also caused the torque monitoring
interlock program for the muon rotating target to stop
working as a Machine Protection System (MPS). Here,
we report the causes of these troubles and how they
were dealt with.
2. Replacement of the DB2 coils
As shown in Fig. 1, the bending magnet DB2 deflects the beam by and directs the muons to the downstream experimental areas. As more than 40 years havepassed since DB2 was manufactured, there were someconcerns about the coil insulation degradation, so thewhole process from hollow conductor selection to coilreplacement was carried out according to a three-year
plan.
We calculated the field of DB2 with a 3-dimensional
field analysis program (OPERA-3d). The analysis modeland actual DB2 are shown in Fig. 2.
The coil replacement work was carried out by removing the end-guard and then dividing DB2 into upper and lower sections using a crane in the MLF. Figure 3
shows DB2 after the coil replacement.
Performance tests and magnetic field measurements were carried out after the coil replacement wascompleted. Table 1 shows the results of the performance

Figure 1. Decay muon beamline (D-line).

Figure 2.	
DB2 analysis model (left) and existing bending
magnet (right).

Figure 3. DB2 after the coil replacement.

147

Muon Science

MLF Annual Report 2021

inspection at the current rating of the existing power
supply (400 A). It was confirmed that the measured andcalculated values generally agreed with each other. We
also measured the excitation curve at the pole center,and the magnetic field along the beam axis at ±250 mm
from a reference point at the pole edge as shown in
Fig. 4. Figure 5 shows the measured excitation curve,

Table 1. Results of the performance inspection.
Calculation
400
43
0.204
0.1146
0.599

Measurement400
44.9
0.299 (120 Hz)
0.1051
0.598

12

12

0.1
21
0.87

0.1
21
0.87

12.5

10

By[T]

Current [A]Voltage [V]Inductance [H]Resistance [Ω]Magnetic field [T]Number ofwater channels[channels/coil]
Pressure drop [MPa]Water flow [L/min]
Flow velocity [m/s]Temperature rise ofcooling water Δt [°C]

the magnetic field according to Ampere’s law, and thecalculated values obtained from the OPERA-3d model.
It can be observed that the measured values are in good
agreement with the calculated values. Figure 6 shows
the magnetic field along the beam axis. Discrepancies
were observed at the fringe field, possibly due to themisalignment of the magnet and the beam duct.
Assuming that the duct was misaligned by 10 mm in
the beam direction, the results were in good agreementwith those measured with the old coils.
When we replaced the coils, the number of coolingwater channels of the new coils was increased from 3
to 6 channels per coil to enable the transport of highmomentum muons up to 250 MeV/c. Table 2 shows thecalculated temperature rise of the cooling water with
an applied current value of 510 A, which is required totransport muons of 250 MeV/c. In J-PARC, the operational conditions for cooling water are defined as a flow
velocity of less than 2 m/s and a temperature rise of lessthan 25°C. The temperature rise of the cooling water inthe old coils would exceed this last condition, whereas

0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
-300

-100

new coil

z[mm]

100

300

old coilFigure 6. Magnetic field measurements.

Table 2. Calculation of transport 250 MeV/c muon
Figure 4. Reference point for magnetic field measurements.

By[T]

0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0

0

100

200

Measurement
Caluculation

300

I[A]

400

500

Ampere's law

Figure 5. Excitation curve at the pole center.

148

Cross section ofhollow conductor
Cross section [mm2]Resistance (20 °C) [Ω]Number of water
channels [channels/coil]
Pressure drop [MPa]Water flow [L/min]
Flow velocity [m/s]Current [A]Temperature rise ofcooling water Δt [°C]

Old coil□12×12-□6×6
108
0.1176

New coil□12×12-Ø6.5
110.8
0.1146

6

12

0.1
15
1.26
510

0.1
21
0.88
510

29

20

MLF Annual Report 2021

Muon Science

the new coils meet the requirements, indicating thatthey can be used at J-PARC.
3.	Status of updating the MPS program for the Muon
target3.1 Display for the muon target in the MLF control
room
Figure 7 shows the display for the muon rotatingtarget in the MLF control room. When a hunting phenomenon occurred in the motor torque for the rotationof the muon target, the indicator lamp for the reverse
rotation was blinking. According to the specifications,the reverse rotation indicator lamp must stay the same
until the rotation has stopped. This indicated that there
were some problems with the muon target rotation display system. Furthermore, since the graph that logs thetorque values of the motor for the muon rotating target in the MLF control room showed torque fluctuation,
also referred as hunting, with intense amplitudes, it waspredicted that these two matters were related. Figure 8
shows a graph of the torque values for the muon target
rotation motor.
3.2 Cause of failure for the MPS of the muon target
The control system for the muon target, including
the muon target rotation control function, is installed in
MLF experimental hall No. 2. This control system is used
for the MPS of the muon target, and it seemed to be themain cause of the current problems [3].
In order to stop the rotation of the muon target
safely, because of some mechanical resistances occurring in the rotation mechanism of the muon target, a
MPS interlock fault is generated when the torque valueof the muon target rotation motor exceeds a set threshold value. Initially, to prevent false MPS alarms due toelectrical noise, the MPS signal was not generated immediately after an increase of the torque value, but only
when the value increased continuously for one second.
But with this method, if the torque value repeats intermittent increase and decrease within one second above
the threshold, like in the case mentioned above of intense torque fluctuation such as hunting, a MPS signal
cannot be generated. Figure 9 shows a comparison of
two cases with and without MPS interlock fault generation when the torque threshold at which the MPS alarm
occurs is set at 8% of the motor rated output ratio. The
figure shows that the MPS alarm will not be generated
unless the torque value exceeds the MPS threshold value for a consecutive period of time.

Figure 7.	Display for the muon target in the MLF control
room.

Figure 8.	Graph of torque values for the muon target rotation
motor showing hunting behavior.

Figure 9.	Comparison of the cases with (left) and without(right) MPS alarm generation.

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3.3 Malfunction of the rotation indicator lamp
The reason for the wrong blinking of the lamp indicating the muon target reverse rotation was almost thesame. In the case of the indicator lamp, the direction ofrotation was obtained from the polarity of the torquevalue. Two timers were also used in the circuit for detecting normal and reverse rotation. The amplitude of
the torque values was so intense that it quickly changed
polarity, and it became impossible to detect the direction of rotation of the muon target, thus resulting in incorrect blinking of the indicator lamp.
3.4 Temporary and future measures
As a temporary measure, the timer was removed
from the MPS alarm generation and detection of the rotation direction circuits. The MPS program was modified
to immediately generate a MPS alarm when the instantaneous torque value exceeds the threshold. However,to avoid malfunction due to noise, the MPS threshold
was set to 25% of the motor rated output. For the circuitthat detects the direction of rotation of the muon target,
the method of detecting the polarity from the torquevalue was changed to a method that detects states ofthe operation switch on the control panel.
Further, when the muon target was rotated in thereverse direction, the torque value of the rotation motor
was higher than that in the normal direction, resulting ina certain tendency for the muon target to be unstable.
In the MLF operation so far, in order to make the wearof the rotation mechanism and bearings uniform, thenormal and reverse rotation operation were alternately
used every few months. However, normal rotation only
will be used for the time being.
4. Summary
A three-year plan from hollow conductor selection
to coil replacement was established, and this year, thefinal year, coil replacement and magnetic field measurements were carried out. In the performance inspection
after the coil retrofit, it was confirmed that each parameter was in general in agreement with the calculated

values. The results obtained from the magnetic fieldmeasurements did not agree with the old coils at thefringe field, but assuming a misalignment of the magnet
and the beam duct, the results agree well with the oldcoils. Furthermore, the number of cooling channels wasincreased, and the magnet was upgraded to be able totransport high-momentum muons (≤ 250 MeV/c). The
DB2 dipole magnet with the new coils was reinstalledin the beamline and is now operating smoothly without
the need of re-tuning the muon beam optics.
The update of the MPS program for muon target
became necessary because of a hunting phenomenon
that occurred in the torque value of the motor for therotation of the muon rotating target, which resulted in aserious problem in generating MPS alarm for the muontarget in FY2021. Although temporary measures havebeen taken to continue the operation, it is necessary to
optimize the MPS program in the future in order to copewith the occurrence of hunting, as well as to determine
the parameter settings of the motor, which is likely causing torque fluctuation such as hunting.
5. Acknowledgements
We are grateful to Dr. Y. Irie and Mr. R. Shimizu forhelpful discussions and technical support during themagnetic field measurements. We would like also to
thank Dr. Y. Bessho for his continuous support.
References[1] T. Yuasa and Y. Kobayashi et al., Muon Beamlines
and Control System, KEK-MSL REPORT 2020, KEK
Progress Report 2021-6 (December 2021), 9-11.
[2] H. Fujimori and T. Yuasa et al., Muon Beamlines andTarget Control System, KEK-MSL REPORT 2019, KEK
Progress Report 2020-4 (October 2020), 13-15.
[3] Y. Kobayashi and S. Makimura et al., CONSTRUCTION
OF CONTROL SYSTEM FOR MUON ROTATINGTARGET AT J-PARC, The 8th Annual Meeting ofParticle Accelerator Society of Japan, August 1-3,
2011, Epochal Tsukuba, 559-563. (in Japanese).

T. Yuasa1,2, Y. Kobayashi1,2, H. Fujimori1,2, S. Matoba1,2, N. Kawamura1,2, P. Strasser1,2, Y. Ikedo1,2, A. Koda1,2, K. Sakai3, A. Watanabe4,
S. Sakata4, M. Meguro4, K. Kawabata4, and H. Sunagawa4
1
Muon Science Laboratory, Institute of Materials Structure Science, KEK; 2Muon Science Section, Materials and Life Science Division,
J-PARC Center; 3Japan Atomic Energy Agency, JAEA; 4NAT Co., Ltd.

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Muon Science

Commissioning of the Ultra-slow Muon Beamline in FY2021
1. Introduction
Muons play an active role in materials science as microscopic magnetic probes. In accelerator-based experiments, muons are obtained as decay products of pions,which are produced by irradiating a fixed target witha proton beam. Muons produced near the surface of a
production target are called “surface muons.”
Surface muon beams have been used since the mid1980s in meson factories around the world. The nearperfect spin polarization, monochromaticity, and highintensity of the beams brought many results in materials
science. However, their kinetic energy of 4 MeV requiresa sufficiently thick sample or a degrader. The large spatial and energy spread of the beam has limited its use tobulk sample measurements.
To overcome the limitation of the implantation
depth resolution of surface muons, the ultra-slow
muon (USM) project by laser ionization of muonium isunderway at J-PARC MLF MUSE. The surface muon beam
delivered by the Super-Omega beamline irradiates a
muonium production target, and muonium in a vacuum
is dissociated by laser ionization. This method producesvery slow muons with kinetic energy corresponding to
the target temperature. Using the USM, unique experiments to selectively implant muons near interfaces inmaterials and depth-resolved muon spin spectroscopy
are possible.

obtained by knife-edge scanning with movable slits [2].
The USM beam intensity needs to be increased forthe start of the user programs. A detailed understanding
and systematic optimization of the transport optics isessential for this purpose.
4. Progress in FY2021
In FY2021, the MCP detector at F3 was replaced bya delay-line detector (DLD). The MCP-DLD detects the
position of a particle from the time difference by readingout both ends of the wires that collect the charge amplified by the MCP. Rapid profile measurements using the
MCP-DLD made it possible to scan multiple parameters.
A typical result on a two-dimensional scan of the MB
currents and the EB voltages is shown in Fig. 2.
Figure 2 shows three regions of large yield, eachcorresponding to a different beam profile. Since a wellfocused beam is better suited for smaller samples, it is

2. The USM beamline
The U1 facility consists of a surface muon beamline,
muonium production target, optics for ionization laser,
electrostatic lens for extraction, and transport optics.
Figure 1 shows a layout of the transport optics. The
beamline has two branches, U1A for USM-μSR and U1B
for transmission muon microscope.
3. Present status and tasks
The Super-Omega beamline delivers the world’s
most intense pulsed surface muons. The total flux of thebeam is on the order of 108 μ+/s [1]. The typical USM flux
is about 2 × 102 Hz after EB1 with the Lyman-α light’s
pulse energy of 5 μJ.
The parameters of the transport optics have been
optimized by maximizing the USM counts at the microchannel plate (MCP) detector installed at F3. However,
the total flux and the profile are essential for optimization. The detector at F3 has been operated with a single
anode without position sensitivity. The beam profile was

Figure 1.	The USM beamline in the U1 area. USMs are obtained by laser ionization of muonium atoms produced at the target (Mu). The transport optics has
electrostatic quadrupoles (EQ), the magnetic bend(MB) for momentum selection, the electric bends(EB) for energy selection, the electric deflector (ED)for beam destination switching, and detector
ports (F).

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beneficial to optimize the transport optics by taking the
profile into account rather than simply using the yieldas an indicator.
As a starting point, the transport optics were tuned
using the Zone C setting shown in Fig. 2. The voltages ofthe five EQs from EQ01 to EQ05 were changed to searchfor conditions where the beam width becomes narrower. The results of comparing the profiles before and after
the adjustment are shown in Fig. 3. The tuning shaped
the beam width to a standard deviation of 1.8 mm (horizontal) and 1.6 mm (vertical). This beam profile is narrow
enough compared to typical μSR samples.
In addition to the MB:EB scan, S2:S3 scans of theextraction electrodes [3], and two-dimensional scans ofeach EQ pair were performed to optimize the parameters. These measurements enabled systematic and efficient optimization of strongly correlated parameter
pairs. The optimization method will be extended tohigher dimensions to achieve a comprehensive understanding of transport optics.

Figure 2.	The result of yield and profile measurements froma two-dimensional grid scan of the magnetic andelectric bends. The top left figure shows the yield,
and the remaining three plots show the profile inzones A, B, and C, denoted in the top left.

5. Summary and prospects
In the FY2021 commissioning, a method to optimize
beam transport parameters using the MCP-DLD was established. From the next campaign, the USM intensity
will be increased by improving the laser pulse energy
and searching for a highly efficient muonium production
target, aiming at the start of USM-μSR user programs.

References[1] The total beam flux is 6.4 × 107 μ+/s at 212 kW. Y.
Miyake et al., JPS Conf. Proc. 21 (2018) 011054.
[2] A. D. Pant et al., JPS Conf. Proc. 21 (2018) 011060.
[3] The extractor consists of four electrodes from S1
to S4, see P. Strasser et al., J. Phys.: Conf. Ser. 551
012065 (2014).

Figure 3.	Comparison of beam profiles before and after adjustment. Group A corresponds to before adjustment, B to after. The projections were obtainedusing the bin that gives the largest yield and thefour bins before and after it.

S. Kanda1,2, T. Adachi3, Y. Ikedo1,2, Y. Oishi1,2, and K. Shimomura1,2
Muon Science Section, Materials and Life Science Division, J-PARC Center; 2Institute of Materials Structure Science, KEK; 3Nishina Center
for Accelerator-Based Science, RIKEN

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Muon Science

USM Commissioning at U1B area [J-PARC: 2021B0001]
The 5 MeV muon-cyclotron system has been constructed at the KEK Tsukuba campus, and was installedat the U1B area (see Fig. 1). The cyclotron is employedto accelerate the 30 keV ultraslow muon beam to 5 MeV
for transmission muon microscopy (TµM). The TµM willvisualize thick objects (>10 µm) in nanometer resolution. Quantum coherence of the ultra-slow muon beam,and deep-penetration power of the muon beam accelerated to 5 MeV will expand its capabilities.

1. Details of the muon cyclotron
The accelerated muon beam should have quite
small energy dispersion (ΔE/E~10–5) to reduce chromaticaberration of the object lens of the muon microscopy.
To realize such a small energy dispersion, flat-top RF acceleration technology is employed, namely, not only thetwo main RF-cavities of 108 MHz (main Dee) but alsoa flat-top RF-cavities (flat top Dee) of 324 MHz are installed in the cyclotron (see Fig. 2).

Figure 1.	The 5 MeV muon-cyclotron system installed on the U1B area. The
center block is the main body of the muon cyclotron, and the 2cabinets are the 108 MHz/20 kW RF amplifier system including a
low-level RF controller system.

Figure 2.	Internal structure of the 5 MeV muon-cyclotron. The ultraslow
muon beam is injected at the center, and is accelerated by
the Dees. The RF power is provided by the coaxial waveguide.

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2. RF Controller and Power Amplifier
The cyclotron requires RF power of 108 MHz/20 kW
to accelerate the muon beam to 5 MeV energy by lessthan 1µsec. It also requires 324 MHz RF less than 1 kW
for flat-top acceleration. We constructed the low-level
RF controlling system (Fig. 3) and the power RF amplifiers (Fig. 4). The low-level RF control system works to
produce stable RF resonance in the cyclotron by driving
the tuner of the cyclotron and controlling the amplitude and phase of the input RF powers. The controller

consists of the fast A/D and D/A converters and FPGAs.
Complex modulators and demodulators are used for adigitalized super heterodyne system.
The power RF amplifier consists of 16 RF-amplifiersof 1.5 kW and 16-way RF-combiner (Fig. 4). All systems,
including the low-level RF controller except for the combiner, are stored into 2 cabinets.
At the next beam time from November 2022, thecyclotron system will be started to work.

Figure 3. Low-level RF controller system.

Figure 4.	Internal structure of the 108 MHz / 20 kW RF Amplifier
System. Panels of the cabinet are removed for tuning.
The front pipe is the 16-way RF combiner.

Y. Nagatani1, T. Yamazaki1, J. Ohnishi2, A. Goto1, T. Yuasa1, S. K. Dey1, T. Adachi1, and Y. Ikedo1
Muon Science Laboratory, Institute of Materials Structure Science, KEK; 2Nishina Center, RIKEN

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Muon Science

The Progress of Laser System for Ultra-Slow Muon Generation
1.	Introduction
Ultra-slow muons are attracting an increased attention as a probe for particle physics and material science.
These ultra-slow muons are generated by stopping
surface-muons in a target and ionizing the evaporated
muonium by irradiating of coherent lights. To realize
efficient ionization of muonium, vacuum ultraviolet(VUV) light (Lyman-α light) and coherent light withwavelengths shorter than 360 nm are required. So far,over 10 µJ Lyman-α light has been successfully generated and applied to ultra-slow muon generation. In thispaper, we report on the additional equipment to keep
stable irradiation of the Lyman-α light.
2.	Problem in the reduction of Lyman-α light intensity
Ultra-slow muons can be generated by resonant
optical ionization of thermal muonium from hot-W
foil target. 122.09 nm (Lyman-α) and 355 nm coherent
pulses are required for 1s to 2p state excitation and 2p toionization, respectively. The high-energy pulsed coherent Lyman-α light source is one of the very importantelements for the efficient generation of the ultra-slow
muons. The design of the Lyman-α light source system
is described in Ref. 1. More than 10 µJ Lyman-α pulse isstably generated in a krypton/argon mixture filled gascell by the methods of two-photon-resonant four-wavemixing, which require 212.556 nm and 820 nm pulses.
Vacuum ultraviolet light has high photon energy, which
over time causes degradation of optical materials. In
addition, photochemical reactions that occur between
vacuum ultraviolet light and residual gaseous, mainlyhydrogen and carbon that cannot be evacuated by aturbo molecular pump in a vacuum, cause performancedegradation of Lyman-α steering mirrors. Degradationof the optics causes a decrease in the ultra-slow muonyield and beam downtime for optics replacement. This
LiF 6° wedged
MgF2 window window

is a problem for future experiments.
The equipment setup of the Lyman-α light generation and propagation for the ultra-slow muon generation is shown in Fig. 1. Lyman-α light is generated in agas cell and propagates through the lithium fluoride
window, which is separating the gas and the ultrahighvacuum. Inside the ultrahigh vacuum, a steering and afocusing mirrors are placed to control an irradiating position and beam shape.
Even in an ultrahigh vacuum of about 10–6 Pa, there
are many light elements such as hydrogen and carbon as residual gases, so interaction with the Lyman-α
light is inevitable. In the optical path, hydrocarbons areformed by ionization of the residual gas and depositedon the mirror surface with a certain probability. If thisdeposition of hydrocarbons continues for a long time,
the reflectance decreases significantly due to scatteringand absorption of Lyman-α light. If the same spot is continuously irradiated with Lyman-α light for a long periodof time, cloudiness on the surface of the mirror is obviously observed. The photo of a clouded mirror is shownin Fig. 2. Each of the colored spots is a laser irradiatedpoint accumulated over 3 weeks or a longer period. The
performance degradation of the window and mirrors as
a function of the irradiation time, as shown in Fig. 3. The
fastest intensity reduction component is caused by Kr/Ar
mixture degradation and it is recovered every 3 hours byautomatic change of the mixture. The second reduction
component is the degradation of transmittance at a gas
cell window caused by color center. The intensity reduction is recovered by displacement of the window every
3 days. The residual intensity reduction component isdegradation of the mirror reflectance. As you can see
in Fig. 3, the intensity of Lyman-α after 8 days will bedecreased to 50% of the maximum intensity when the
mirror irradiation position is not changed.
dielectric multilayer mirror
R=80%@122 nm

ultrahigh vacuum

Gas cell
Sodium salicylate plate
Omega 1Omega 2
Lyman-α355 nmKr/Ar gas355 nmPhotodiodeSurface muon
Hot W

metal enhanced mirror!
R=80%
Ultra-slow muon

Figure 1. A schematic of Lyman-α generation and propagation setup for ultra-slow muon generation.

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3.	Mirror steering and displacement system
This year, we introduced a drive mechanism thatcan change the laser reflection position on the mirrors
for vacuum ultraviolet light to recover the reflectivity ofthe two mirrors. The equipment adds a mirror displacement function to the mirror mount that can adjust thehorizontal angle and vertical tilt of the mirror. The mirror
mount located upstream has a rotation stage to rotatea ø50 mm circular shape mirror and a linear stage fortranslation (30 mm stroke). The mirror mount on thedownstream side uses a 50 mm square shape cylindrical mirror, so horizontal and vertical translation stages
were introduced. The installed mirror mounts are shownin Fig. 4. These stages are equipped with built-in encoders so that the movement history of the mirror position
can be recorded, allowing the laser reflective surface tobe set to the unirradiated area when the reflectivity ofthe mirror decreases. The new mirror steering and displacement system enables the mirror irradiation position adjustment by remote control without opening thevacuum chamber to the atmosphere.
4.	Summary
A mirror steering and displacement system wasintroduced to maintain high intensity of the Lyman-α
light, which directly affects the yield of ultra-slow
muons.
The newly introduced mirror steering and displacement system significantly reduces the maintenancework and enables long-time ultra-slow muon experiments. However, the size of the steering mirror is finite,
it will still be necessary to replace it with the vacuum
chamber opened during beamtime. Since the frequency of mirror replacement is expected to increase as the
Lyman-α intensity increases, we plan to remove hydrocarbons in the vacuum chamber using a NEG pump inorder to extend the mirror’s lifetime.

Figure 2.	Typical degraded mirror. Several colored spots on
the mirror surface are laser irradiated.

Figure 3. The typical time revolution of Lyman-a intensity.

Acknowledgement
This work was carried out with Mr. K. Hosoya andProf. S. Nakamura at Ibaraki Univ.
Reference[1] N. Saito et al., Opt. Express, 24, 007566 (2016).
Figure 4.	Installed motorized mirror mount with translation
stages for steering and displacement of the VUVmirror.
Y. Oishi1,21Muon Science Laboratory, Institute of Materials Structure Science, KEK; 2Muon Science Section, Materials and Life Science Division,
J-PARC Center

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Muon Science

Present Status of the S-line
The S line has been designed and constructed tomainly utilize surface muon beams, with a second
planned experimental area, S2, starting its operation in
2021. The use of the kicker device allows double pulses
to be used simultaneously as single pulses for the twoareas currently in operation, S1 and S2. In this respect, astable operation of the kicker device is very important.
The configuration of the kicker device and theprevious troubles have been reported in earlier MSL
reports [1]. The 600 V DC power supply failure, which
had often occurred since the S line began operation in2017, has not happened since the addition of smoothing capacitors in the summer of 2019. On the other
hand, MARX board failures have continued to occur
several times per year. Most of the failures were causedby damage to the charge current detecting resistor, andeach time a failure occurred, the manufacturer replaced
the resistor with a high-surge resistance resistor. Since
the repaired boards have never failed again, we decided
to replace the resistors on 384 MARX boards during thesummer shutdown period of 2021, before the beginning of a full-scale simultaneous operation of S1 andS2. The work was performed by subcontracting staff. It
took about 100 man-days over a period of about twomonths, with a maximum of three people per day whowere relatively free for other maintenance work.
Another issue, the location of the kicker power supply unit, was also addressed during the summer shutdown period. Conventionally, the kicker power supply
unit was installed inside the S-line concrete shielding.
This was because it was unknown how much the noise
generated by the electric field kicker would affect theexperiment. However, with this method, whenever a
MARX board failure occurred, the concrete shielding had
to be opened and replaced, and this required waiting for

the weekly maintenance day. Moreover, the work had tobe done under very tight schedule, including checking
the restoration of the shielding so as not to affect theoperation resumption schedule. Therefore, we decided
to relocate the kicker power supply unit to the fourth
floor of the power supply yard. Originally, the kicker
power supply unit had a coaxial cable delay line so thatthe reflected pulses would come after the muon data
window, and the coaxial cables were wound on drums
and installed in the concrete shielding. In the relocation
work, the coaxial cables were unwound from the drums
and connected to the kicker power supply unit on the
fourth floor of the power supply yard through an independent cable rack to prevent noise from the electricfield kicker operation from affecting other equipment.
In December, an engineer representing the manufacturer visited J-PARC MLF to conduct a comprehensive operation verification test and confirmed that
there were no problems with the generated voltage
waveforms. Unfortunately, there were times when thesystem had to be shut down due to the MARX board
failure even after the maintenance works performed in
the summer of 2021. However, there has never been afailure caused by damage to the charging current detection resistor, and all failures are now due to damage to
the FETs. In addition, operation can be resumed up tohalf a day after a failure is detected, which is a significant
improvement from the previous situation where it took
up to seven days to resume operation. The manufacturer
is currently investigating the cause of the FET failures
and working on preventive countermeasures.
Reference[1] K. M. Kojima et al., KEK Progress Report 2018-2(2019) 16-17.

A. Koda, T. Yuasa, J.G. Nakamura, S. Nishimura, P. Strasser
Muon Science Laboratory, Institute of Materials Structure Science, KEK

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Development of Sample Environment at the S1 Area
− Reorganization of Electrical Systems −In this work, the electrical systems of the “sample
environment equipment, which can be changed according to experimental conditions,” and the “beamline vacuum pumps” were separated at one upstream breaker,
as shown in Fig. 1. As a result, the vacuum system of thebeamline is no longer affected by troubles during sample environment operation with user experiments.
The 2021 survey also revealed in this S1 area experimental panel that several cable taps and fourother taps called JAERI taps (referred to as JTAP) wereextended from the 15-A trip (AT) breakers and 20 AT
breakers, respectively. The price of this JTAP was about
100,000 yen, which is expensive, but the cable and tap
are solidly made and can be rolled on the floor at the
MLF. The commonly distributed table taps, as the namesuggests, are designed to be installed on tables, etc.,
and it is considered inappropriate to install cables andtaps rolling on the floor from the standpoint of electricalsafety. Although JTAPs are highly convenient at the MLF,
they are not suitable for connecting loads that use large
amounts of power. This is because the eight connection
ports induce over-connection of the loads. Therefore, inthis work, when large loads such as vacuum pumps and

The sample environment equipment for the μSR
experiment receives its power supply from the S1 area
experimental panel, which is the downstream distribution panel in the S1 area, to which various other piecesof equipment are connected. For example, “detectors
and servers for μSR measurements” and “vacuum pumps
for the beamline” are connected to the distribution panel. Although these devices were separated at the end
breakers of the distribution board according to theirrespective characteristics, they were mixed up to one
breaker upstream, according to the 2021 survey.
At the MLF, J-PARC, strict controls are generally inplace to ensure electrical safety. One of the results ofthis is that the breakers of the distribution boards, whichwere installed according to the electrical safety application, ensure protective coordination based on theircatalog specifications. It means that the downstream
breakers have a faster time to operate, and in principle, the downstream breakers trip in sequence, so thatthe upstream breakers do not operate first. In practice,
however, there are various transient phenomena, andthe phenomenon of one upstream breaker tripping firstcan sometimes occur.
Series 20 Breaker 50AT

Pump
SRP3-1

Series 30 Breaker 50AT

Series204
20AT

Series 202 Series
20AT
203
20AT
Outlet Tap(1)
Pump
SRP1
Detectors

Series 201
20AT

OutletTap (5)

Outlet Tap (4)

Pump
SRP2

Pump Unit

Compressor

Pump
SRP3-2

3He Cryostat
Controller

Series 304
Series301, 302, 15AT
303
Outlet Tap
15AT
19-inchrack
ServerCameraRadiation
MonitorSeries 40 breaker 50AT
Series
401
20AT
JAERI
Tap

Series402
20AT

Series403
20AT

Cooling
Water
Chiller (2)Others (<5 A)
Outlet Tap (3)Leak
Detector
Pump Unit

Sample Rod
Controller

Series 404
20AT

JAERI Tap

LAN
HUB

Pump
for HeOutlet Tap

Gauge
Display
LED Light

Figure 1.	Electrical system diagram of the S1 area experimental panel, consisting of three series (20, 30
and 40) connecting to upstream breakers. The beamline vacuum pumps are shown in red letters. The blue and green letters indicate the sample environment equipment: the former is tobe changed according to the experimental conditions, and the latter is to remain unchanged.

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cooling water chillers were connected to the JTAP, theJTAP was removed and taps with a smaller number ofconnections were laid and organized for connection asshown in Fig. 1. At this time, in the wiring from the 20 AT
breaker, a terminal block was installed and branched toconnect two outlet taps, so that the load connected peroutlet tap would not exceed 15 A. This is because theupper limit for use of the outlet taps is 15 A. If the outlet
tap is directly connected to a 20 AT breaker, the upper
limit of use would be 15 A.
Note that in this work four new cables were laid
when reorganizing the electrical system (Fig. 2). The

Muon Sciencecables used were 2PNCT8sq-3C and 2PNCT2sq-3C,
standard cables that are relatively soft and can be rolledon the floor. There was also an outlet installation on
the 100 V 20 AT and 15 AT breakers, which was not anelectrical work that required an application for use inaccordance with the J-PARC Center Safety Management
Regulations. An application for use is required for electrical works with a voltage exceeding 750 V for direct
current and 600 V for alternating current, and for electrical works with a rated output exceeding 7.5 kW or
7.5 kVA or a rated current exceeding 30 A.

Figure 2.	Cable installation and outlet taps from the S1 area experimental
panel installed in this work. (1) to (5) numbers correspond to thoseshown in Fig. 1.

J. G. Nakamura1,2, T. Yuasa1,2, M. Meguro3, S. Nishimura1,2, and A. Koda1,2
Muon Science Laboratory, Institute of Materials Structure Science, KEK; 2Muon Science Section, Materials and Life Science Division,
J-PARC Center; 3NAT Corporation

1

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H-Line Commissioning
The H-line is a muon beamline in the east #1 experimental hall of the MLF. It is a general-purpose beamline [1] that can generate both positive and negative
muons. Its design intensity of surface muons reaches
108 muons/s with a proton beam power of 1 MW thanks
to the large acceptance (108 mSr) of its capture solenoids and other beamline magnets with large apertures.
The H-line has two branches named H1- and H2-area.
The first branch (H1-area), where the hyperfine splitting
measurement of muonium (MuSEUM experiment [2])and search for a cLFV (charged Lepton Flavor Violation)
process (DeeMe experiment [3]) are planned, has begun operation after the summer shutdown in FY2021.
The second branch (H2-area) is under construction andaimed at experiments using a low emittance muon
beam obtained by re-accelerating ultra-slow muons,such as the muon g-2/EDM experiment [4] and a transmission muon microscope (TμM) project.
The beam commissioning of the H-line has begun
in January 2022. During the beam commissioning, large
positron/electron background existed because the DC
separator was not installed yet. It made the beam commissioning difficult, but we managed to measure beam
intensity, profile, and momentum of surface muons. The
beam intensities of negative muons at several momenta
were also measured.
Figure 1 shows the setup to measure muon beam
intensity. Decay positrons from the muon stopping
target are measured using a pair of plastic scintillators.
From the number of detected positrons (see Fig. 2) anddetector acceptance estimated using a Geant4-based
simulation [5], the preliminary result of surface muon
beam intensity was estimated to be (8.3 ± 0.7) × 107
muon/s for 1 MW proton beam. This is about 75% of our

Figure 1. Setup of the beam intensity measurement.

160

expectations. We expect to recover the remaining 25%
by modifying the power supplies of the muon capturesolenoids. Due to the speculations of the power supplies, the rated currents cannot be applied now.
The momentum of surface muons was measured
with almost the same setup as the intensity measurement. In the momentum measurement, a magnetic fieldof 23.85 G was applied to an aluminum target of various
thicknesses. Due to the muon spin rotation in a magnetic field, the time spectrum of decay positrons showed
wiggled structure. In Fig. 3, the beat amplitudes are plotted as a function of the thickness of the Al targets. The
range of surface muons in Al was obtained by fitting thisplot with an error function, and then we estimated thebeam momentum to be 28.0 MeV/c (RMS 1.2 MeV/c),which was consistent with our expectation.

Figure 2.	Time spectrum of decay positrons in the intensity
measurement of surface muons.

Figure 3.	Muon range measurement to estimate surface muons.

MLF Annual Report 2021

Muon Science

Figure 4.	Typical beam profile of surface muons at the H1
area.

Figure 5. Negative muon yields at the H1-area.

The beam profile of surface muons was observed
using a beam profile monitor developed by T. U. Ito(JAEA), et al. [6]. A typical beam profile at the H1 area isshown in Fig. 4 and its horizontal and vertical beam sizes
are σx = 44 mm and σy = 24 mm, respectively.
The commissioning of negative muons was also
conducted. Beam intensities of negative muons withseveral momentum setups are shown in Fig.5. The
measured results have a good agreement with Geant4based simulation of negative muons at the H1-area. Tthe
plateau over 50 MeV/c is also due to the speculationsof present power supplies of the capture solenoids. By
modifying the power supplies, the capture solenoids
can capture pions with higher momenta, resulting in
more negative muons with higher momentum at theH1 area.
In the first beam commissioning at the H1-area, wemeasured beam intensity, momentum, and profile ofsurface muons and beam intensities of negative muons
with several momentum setups. The commissioning has
demonstrated that the beam performance of the H-line
was almost as expected, given the present speculationsof the power supplies of the capture solenoids. Next
commissioning is planned after the modification of thepower supplies and installation of a DC separator (Wienfilter), both of which will be conducted in FY2022.
Acknowledgments
The authors are grateful to T. Ushizawa, S. Sugiyama,
K. Hase, Y. Higashino, S. Kaneko, R. Tagawa, H. Tada, T.
Mibe, and all members who joined the commissioningat the H1 area.
References[1] N. Kawamura, et al., Prog. Theor. Exp. Phys. 2018(2018) 113G01.
[2] K. Shimomura, AIP conf. proc. 1382 (2011) 245.
[3] H. Natori, et al., Nucl. Phys. B (Proc. Suppl.) 248-250(2014) 52-57.
[4] T. Mibe, et al., Chin. Phys. C 34 (2010) 745.
[5] S. Agostinelli, et al., Nucl. Instrum. Methods Phys.
Res. A 506 (2003) 250-303[6] T.U. Ito, et al., Nucl. Instrum. Methods Phys. Res. A
754 (2014) 1-9

T. Yamazaki1,2 and N. Kawamura1,2
Muon Science Section, Materials and Life Science Division, J-PARC Center; 2Muon Science Laboratory, High-Energy Accelerator Research
Organization (KEK-IMSS)

1

161

MLF Safety

MLF Safety

MLF Annual Report 2021

Research Safety
1. Radiation safety
Maintenance of SAmple Radioactivity Evaluation program
SAmple Radioactivity Evaluation program (SARE) is
continuously maintained to estimate the radioactivity ofan irradiated sample for instrument groups. The estimation at all neutron beamlines can be performed by SARE.
SARE is used to bring a sample away from controlledareas. In 2021, radioactivity production by negative muons and a mode irradiated by realistic neutron flux canbe implemented.
Extension of the entry administration system
In 2021, the entry administration system of the controlled was extended to the entrance at the BL09 building and BL22 building. The system provides an entry to
the experimental hall and an exit from it with a certification by an OSL badge (See Fig. 1).
Radiological license upgrade
Although the applications for radiological license
upgrades in FY2020 were approved on April 28, 2020,
the facility inspection was passed on January 27, 2022.
The following items were updated after the application approval in FY2020:(1)	Construction of a High momentum decay muon
instrument (H-line).
(2)	Change of the Accelerator experimental room followed by the construction of H-line.
(3)	Extension of the Surface muon instrument (S-line).
The next application is prepared and is adjusted incooperation with local governments and the nuclear

Figure 1.	Electric lock and OSL reader authorizing the entry
to the controlled area at the BL22 building.

164

regulatory agency. Recently, the licensing process time
has increased and it is possible to apply for the new licensing only once a year.
2. Chemical safety
This year, due to space limitations, only statisticsof the chemical safety check are shown in Fig. 2. Their
number decreased due to the effect of the COVID-19
pandemic.
3. Crane safety
Also, this year, due to space limitations, only statistics of the crane usage are shown in Fig. 3. The usage
was not affected by the COVID-19 pandemic.

Figure 2.	Trend of the amount of user-brought chemical materials for chemical safety check from the start of
the MLF operation to the last year.

Figure 3. Trend of the total crane usage in one year.

MLF Annual Report 2021

4. COVID-19 pandemic measures(1) General overview
As in the previous fiscal year, the MLF division handled the COVID-19 pandemic under the guidelines of
the JAEA and KEK measures and the same measures
were continued. As a result, no user infections occurredat the MLF and the beam time was operated as planned
and there were no facility shutdowns due to the Covid
pandemic.
As a record of specific efforts, photographs of a daily
alcohol disinfection points are shown in Fig. 4, because
it could not be included in last year’s annual report due
to space limitations. The number of times of disinfection
per day was determined according to the frequency ofentry to the point.
(2) Related matters
In response to the spread of Covid-19, we examined
the safety of remote experiments, which are considered
a new experimental method because users do not cometo MLF. In particular, the items to consider are information security, equipment safety by re-mote control, andexport control. The staff carried out a model experimentwith overseas researchers, confirmed some problems,such as communication speed, and made plans to resolve them in the future.
(3) Next year
At the moment, the COVID-19 pandemic has notconverged, so we will continue to take similar measures
next year.

MLF Safety

(b)
(a)

(
(c)

(e)

(d)

handrail

(f)

cabin

(g)
eleva
tor
Figure 4.	Alcohol disinfection points where MLF users enter:(a) entrance elevator, (b) upstairs to the experimental hall, (c), (d) user room. Frequency of (a) – (d)points: 4 times from 9:30-17:30, 1 time from 17:301:00 and 1 time from 1:00-9:30. (e) experimental hallhandrail, (f ) experimental hall cabin, (g) elevator in
the MLF experimental hall. Frequency of (e) – (g)points: 1 time from 9:30-17:30.

M. Harada1, M. Sekijima1, H. Morikawa1, K. Kawakami2, Y. Watanabe2, H. Tanaka2, W. Kambara2, H. Asai2, T. Oku2, K. Suzuya3,
N. Kawamura4, Y. Sakaguchi5, R. Takahashi2, Y. Yamaguchi5, K. Soyama6, and K. Aizawa6
1
Neutron Source Section, Materials and Life Science Division, J-PARC Center; 2Technology Development Section, Materials and Life Science
Division, J-PARC Center; 3Neutron Science Section, Materials and Life Science Division, J-PARC Center; 4Muon Science Section, Materials
and Life Science Division, J-PARC Center; 5Neutron Science and Technology Center, CROSS; 6Materials and Life Science Division

165

MLF Operations in 2021

MLF Operations in 2021

MLF Annual Report 2021

Beam Operation Status at the MLF
1. Overall
In Japanese Fiscal Year (JFY) 2021, the beam operation at the MLF started on April 1, 2021 and ended
on March 31, 2022. In JFY2021, the beam operation
started with a power of 600 kW with a double-bunch
beam. After April 5, the beam power was increased from600 kW to 700 kW. Due to the insufficient cooling power
for the Radio Frequency (RF) cavity at the Rapid Cycling
Synchrotron (RCS), the beam power was decreased to
600 kW in June. The beam period of 2021A was switched
to 2021B on January 15, 2022. In the original beam operation plan determined in early April, the beam operation
after the summer outage was planned to be resumed
on November 21. Since the maintenance involves highrisk, the radiation safety group was prohibited from carrying out simultaneously specific tasks, such as radiation
works related to muon and neutron production targets,so the maintenance schedule was rearranged to besatisfied the requirement. It should be mentioned thatsuch a requirement by radiation safety was only appliedin 2021, which was not in 2022 by the decision of thesafety group. Due to a long duration of a series of maintenance work, the beam operation after the outage wasresumed on January 15, 2022.
The records of the beam power and the availability
are shown in Fig. 1. We had planned to stop the operation during the national holidays from April 28 to May
10. After the national holidays, the beam operation continued up to the morning of July 15. Since insufficientcooling at the RCS RF cavity was expected, the beam
power was limited to 600 kW after June 25. Eventually,
the beam operation could continue up to July 15 asscheduled.
During the outage, the spent target #11 was replaced with a new target #14. During replacement, nosignificant issue was found on the target. Furthermore,since no severe damage was found on target #11, we
decided to continue with the 700 kW beam operation
after the outage. As the outage ended, the beam power
was temporarily limited to 600 kW because the particle
counter reading the beam current of the H0 beam dump
at the RCS, which corrects the beam not to be injected
into RCS, approached its limit. Through the accelerator
study, we found that it was caused by the noise of thebeam current monitor. After solving the noise of thebeam monitor, we continued the 700 kW beam operation again after January 20.
In JFY2021, a high-intensity beam with a stablebeam for users was carried out. Table 1 shows thescheduled time and availability in JFY2021. As shown in
Table 1, a stable beam operation with 97% availability
was achieved up to July 15 for 2021A. Eventually, theoverall availability in JFY2021 was 96.0%.
The beam operation was stopped on several occasions due to minor failures. Typical causes of the beamstops with a duration longer than 3 hours are summarized in Table 2 and described below.

Figure 1. Beam power trend (blue line) at the MLF and availability per day (red line)

168

MLF Annual Report 2021

MLF Operations in 2021

Table 1. Run cycle, scheduled time, actual beam time, and availability.
Run cycle

Duration

Scheduled time (h)Beam time (h)Availability (%)

86
87
88
2021A
2021B
Overall

Apr 1 – Apr 30
May 10 – July 15
Jan 15 – Mar 31
April 1 – July 15
Jan 15 – Mar 31
April 1 – March 31

623
1408
1599
2,031
1,893
3,924

605
1,368
1,511
1,973
1,510
3,483

97.1
92.2
94.4
97.2
94.4
96.0

Table 2. Events that stopped the beam with a duration longer than 3 hours.
Stop dateJune 3June 19
July 14January 16
January 17
January 18
January 23
January 24
February 1 and 2
February 21
March 4
March 26

Cause of beam stop
LINAC klystron failure at HV1
LINAC klystron failure at HV4
LINAC RFQ power supply failure
RCS particles counts for H-0 beam dump
MLF water loop system failure
MLF water loop system failure
MLF water loop system failure
MLF water loop system failure
LINAC klystron failure at HV43NBT AC breaker failure
RCS charge exchange foil turning
LINAC klystron failure at HV4

2. Causes of the beam stop
LINAC:
During JFY2021, there were no shortages of waterflow for the magnet at LINAC, which had been the main
reason for beam stops before JFY2019. In JFY2021, we
had four failures on the klystron providing the RF to thecavities.
3 GeV Rapid Cycling Synchrotron (RCS):At the H0 beam dump, the beam current at the
dump was close to being allowable, except when due
to the noise of beam monitor. On March 4, due to thedisplacement of the charge exchange foil, the actual H0
beam was increased. To resume the beam operation, we
tuned the foil position and the beam.

Stop durationfor each event [h]
5.2
3.2
5.2
3.3
6.4
6.0
4.3
4.5
6.2
6.4
4.7
12.9

Beam transport from RCS to the MLF (3NBT) and MLF
The AC breaker for separation between the commercial electricity and the power supply of the bending
magnet malfunctioned. Because the breaker has beenused since the first day of the beam operation, we supposed that the cause of the failure was aging. Since we
had a spare breaker, the stop duration was relatively
short. If we did not have the spare, the beam operation
would have had to be stopped for several months. We
learned the importance of spare parts to maintain thehigh availability of the operation.
After the summer outage, the water loop systems
for cooling the mercury target vessel and the proton
beam window at the MLF failed four times during beam
operation. The failures were caused by the presence ofgas in the water loop, which exceeded the allowablepressure at the surge tanks.

S. Meigo
Neutron Source Section, Materials and Life Science Division, J-PARC Center

169

MLF Operations in 2021

MLF Annual Report 2021

Users at the MLF
The MLF beam operation for FY2021 started on
April 1 with a beam intensity of 600 kW, and then the
beam intensity was increased to 700 kW on April 5.
However, due to cooling capacity problems, the beam
intensity was reduced to 600 kW in June. The problems
were solved and the 700 kW operation was resumed
on January 20. It should be noted that the overall

availability reached 96%, achieving a very stable beam
supply. The total number of users of the neutron andmuon experimental facilities in FY2021 was 424, almost
the same as in FY2019, due to the COVID-19 restrictions.
The trend for the number of users at the MLF since
the start of the operations in FY2008 is summarized inTable 1 and Fig. 1.

Table 1. The number of domestic and foreign users by fiscal year.
1050

FY2008FY2009FY2010FY2011FY2012FY2013

FY2014

Domestic Foreign Domestic Foreign Domestic Foreign Domestic Foreign Domestic Foreign Domestic Foreign Domestic Foreign
Users
Users
Users
Users
Users
Users
Users
Users
Users
Users
Users
Users
Users
Users
107

Neutron

95

317
12

303

0

38

18

Muon

476
14

432

2

42

40

18
FY2015

259
44

238

8

21

50

FY2016

708
21

628

2

46

23

FY2017

449
80

399

10

50

56

FY2018

824
50

711

11

78

61

FY2019

750

113
91

FY2020

600

13
450

FY2021

Domestic Foreign Domestic Foreign Domestic Foreign Domestic Foreign Domestic Foreign Domestic Foreign Domestic Foreign
Users
Users
Users
Users
Users
Users
Users
Users
Users
Users
Users
Users
Users
Users
559

Neutron

476

852
83

744

10

83

69

Muon

59

927
108

742

16

149

99

965
185

789

30

146

179

940
176

827

15

127

161

113

448

11

88

138

Neutron (Japanese)

Neutron (Foreigners)

Muon (Japanese)

Muon (Foreigners)
30

1050

307
41

257

4

112

92

50
117

15
11
146

16

149

127

13

900

83

78
10
46

750

80
8
42
44

450
2
38
14

300

18
12
95

11

59

4

83

88

50
50
2
21
21

113

10

41
744

711

432

176
185

108

113

600

150

489

742

789

827

5
112

628
50
399

476

303
238

448
257

0
FY2008 FY2009 FY2010 FY2011 FY2012 FY2013 FY2014 FY2015 FY2016 FY2017 FY2018 FY2019 FY2020 FY2021

Figure 1. The number of domestic and foreign users by fiscal year.

170

900

300
150
0

5

F

MLF Annual Report 2021

MLF Operations in 2021

MLF Proposals Summary – FY2021
The proposals for 2021A are not included in Table1. Due to the COVID-19 situation, 2020B and 2021A were combined into one
proposal round. The operations period for the proposals for “2020B+2021A” was from December 2020 to July 2021. Therefore, theproposals for 2021A were included in the FY2020 data as they cannot be counted separately.

Table 1. Number of Proposals by Beamline
Beamline

2021B
Submitted Approved
GU
GU

Instrument

Full Year
Submitted
PU/S
IU

Approved
PU/S
IU

BL01

4D-Space Access Neutron Spectrometer - 4SEASONS

24(0)

8(0)

0

2

0

BL02

Biomolecular Dynamics Spectrometer - DNA

26(2)

7(2)

2

3

2

3

3
1

3
1

0
45 ※

0
0

0
44 ※

0
0

BL03

IBARAKI Biological Crystal Diffractometer - iBIX

(100−β)
†
(β)

‡

2

BL04

Accurate Neutron-Nucleus Reaction Measurement Instrument - ANNRI

10

5

2

1

2

1

BL05

Neutron Optics and Physics - NOP

8

6

1

0

1

0

BL06

Village of Neutron Resonance Spin Echo Spectrometers - VIN ROSE

2

2

1

0

1

0

BL08

Super High Resolution Powder Diffractometer - SuperHRPD

9

5

1

0

1

0

BL09

Special Environment Neutron Powder Diffractometer - SPICA

4

4

1

0

1

0

BL10

Neutron Beamline for Observation and Research Use - NOBORU

16

4

2

1

2

1

BL11

High-Pressure Neutron Diffractometer - PLANET

18(0)

7(0)

0

2

0

2

BL12

High Resolution Chopper Spectrometer - HRC

7

4

1

0

1

0

BL14

Cold-Neutron Disk-Chopper Spectrometer - AMATERAS

47

7

1

1

1

1

BL15

Small and Wide Angle Neutron Scattering Instrument - TAIKAN

36(2)

12(2)

2

3

2

3

BL16

Soft Interface Analyzer - SOFIA

17

5

0

1

0

1

BL17

Polarized Neutron Reflectometer - SHARAKU

17(2)

10(2)

3

3

3

3

BL18

Extreme Environment Single Crystal Neutron Diffractometer - SENJU

22(1)

7(1)

1

1

1

1

BL19

Engineering Materials Diffractometer - TAKUMI

27

12

2

1

2

1

8
22

7
22

0
28

0
0

0
26

0
0

BL20

IBARAKI Materials Design Diffractometer - iMATERIA(100−β)
†
(β)

‡

BL21

High Intensity Total Diffractometer - NOVA

19

15

1

0

1

0

BL22

Energy Resolved Neutron Imaging System - RADEN

19(2)

8(2)

0

2

0

2

BL23

Polarized Neutron Spectrometer - POLANO

4

4

1

0

1

0

D1

Muon Spectrometer for Materials and Life Science Experiments - D1

21(1)

10(0)

1

1

1

1

D2

Muon Spectrometer for Basic Science Experiments - D2

11(4)

4(2)

1

1

1

1

S1

General purpose µSR spectrometer - ARTEMIS

41(0)

18(0)

1

1

1

1

S2

Muonium Laser Physics Apparatus - S2

0

0

0

1

0

1

U1A

Ultra Slow Muon Microscope - U1A

0

0

0

1

0

1

U1B

Transmission Muon Microscope - U1B

0

0

0

1

0

1

H1

High-intensity Muon Beam for General Use - H1

0

0

0

1

0

1

439

197

89

28

86

28

Total

GU : General Use
PU : Project Use or Ibaraki Pref. Project Use
S : S-type Proposals
IU : Instrument Group Use† : baraki Pref. Exclusive Use Beamtime (β = 80%)
‡ : J-PARC Center General Use Beamtime (100−β = 20%)( ) : Proposal Numbers under the New User Promotion (BL01, BL02, BL11, BL15, BL17, BL18, BL22) or P-type proposals (D1,D2, S1) in GU※ : Operations period is held twice per year (for each of the A and B periods), with only the yearly total shown above.
The actual total number of proposals in each beamline named in the table does not match the number shown in the “Total” cell,because some proposals are submitted or approved across multiple beamlines.

Table 2.	Number of Long-Term Proposals by Fiscal Year
Fiscal Year

Submitted

Approved

2019

9

4

2020

13

3

2021

0

0

Due to the COVID-19 situation, no Long-Term Proposals were called for FY2021.

171

MLF Operations in 2021

MLF Annual Report 2021

Number of Proposals

1200
1000
800
600

142

400

42
20

200
0

34
67

214

2008

2009

278

293

395

199

231

245

126
45

309

255

2010

2011

460

422

469

2012

2013

2014

360

329

321

353

2015

2016

607

507

630

626
311

2017

2018

2019

2020

2021

Fiscal Year
Figure 1. Number of MLF Proposals over Time
After publishing MLF Annual Report 2020, additional Fast Track Proposals and Urgent Proposals were approved.
Therefore, the number of proposals of FY2020 was changed in Figure 1.

KEK
36
JAEA 6%
42
8%

CROSS
31
6%

Universi�es (Japan)
Companies (Japan)
Universi�es(Japan)230
41%

Foreign
Organiza�ons
143
26%
Research Companies
Ins�tutes (Japan) (Japan)
25
49
4%
9%

Research Ins�tutes (Japan)
Foreign Organiza�ons
JAEA
KEK
CROSS

Figure 2. Origin of Submitted Proposals by Affiliation - FY2021

172

Not Approved
Approved

MLF Operations in 2021

MLF Annual Report 2021

MLF Division Staff 2021
Toshiya Otomo (Head)

Eiichi Wakai

Kazuhiko Soyama (Deputy Head)

Kyoko Aizawa

Kazuya Aizawa (Deputy Head)
Koichiro Shimomura (Deputy Head)

Neutron Source Section

*: additional duties<JAEA>
Katsuhiro Haga (Leader)

Yuji Yamaguchi

Noriyuki Morikawa

Kenji Sakai (Sub-Leader)

Hui Liang

Shigeto Tanaka

Makoto Teshigawara

Toshiaki Uehara

Shizuka Yoshinari

Masahide Harada

Akihiko Watanabe

Midori Yamamoto

Tomokazu Aso

Hideki Muto

Rie Nemoto

Hiroyuki Kogawa

Akiyoshi Futakawa

Hiroshi Takada *Hidetaka Kinoshita

Mitsuaki Sekijima

Shoichi Hasegawa *Takashi Wakui

Yoshinori Kikuchi

Eiichi Wakai *Motoki Ooi

Masakazu Nakamura

Shin-ichiro Meigo *Takashi Naoe

Hidemitsu Hosokawa

Kenichi Oikawa *Masakazu Seki

Atsushi Akutsu

Tetsuya Kai *Akira Shibata

Toshiyuki Yasuhara

Hiroyuki Uehara *Shiho Takamiya

Hiromi Inoue

Neutron Science Section

*: additional duties<JAEA>
Yukinobu Kawakita (Leader)

Takuro Kawasaki

Masashi Harada

Mitsutaka Nakamura (Sub-Leader)

Maiko Kofu

Daigo Setoyama

Kentaro Suzuya

Wu Gong

Wataru Yoshimune

Ryoichi Kajimoto

Kosuke Hiroi

Takeshi Harada

Takanori Hattori

Naoki Murai

Hideaki Isozaki

Stefanus Harjo

Hiromu Tamatsukuri

Keiichi Inoue

Kenichi Oikawa

Yusuke Tsuchikawa

Misono Fujii

Takashi Ohhara

Wenqi Mao

Naoko Shimizu

Takenao Shinohara

Kanae Ito

Toshiko Goto

Hiroyuki Aoki

Kazuhisa Isegawa

Takeshi Yashiro

Tetsuya Kai

Shigeki Uzuki

Hiroko Uchiki

Seiko Kawamura

Yuki Hirota

Itaru Tamura *Shinichi Takata

Seiya Tanaka

Koji Kaneko *Ryoji Kiyanagi

Rintaro Nakabe

Hiroshi Nakagawa *Kaoru Shibata

Ryo Murasaki

Atsushi Moriai *Asami Sano

Rika Inoue

Satoshi Morooka *Yasuhiro Inamura

Tatsuya Kikuchi

Atsushi Kimura *173

MLF Operations in 2021

MLF Annual Report 2021

Shoji Nakamura *Masao Watanabe *Takeshi Hiromoto *Shunsuke Endo *Dai Yamazaki *Fumiaki Kono *Yosuke Toh *Kazuo Kurihara *Yuya Hanazono *Mariko Segawa *Tarou Tamada *Masahide Harada *Yu Hirano *<KEK>
Testuya Yokoo (Sub-Leader)

Norifumi Yamada

Asami Sano *Shinichi Ito

Takashi Honda

Kazutaka Ikeda

Hideki Seto

Naokatsu Kaneko

Takashi Saito

Toshiya Otomo *Shuki Torii

Sara Yamauchi

Kazuhiro Mori

Hidetoshi Oshita

Taichi Ueta

Takashi Kamiyama

Kaoru Taketani

Go Ichikawa

Hitoshi Endo

Kenji Mishima

Takashi Ino

Hiroyuki Aoki *Technology Development Section

*: additional duties<JAEA>
Takayuki Oku (Leader)

Ryuta Takahashi

Shinichi Takata *Kazuyoshi Tatsumi

Kazuhiro kawakami

Tatsuya Nakamura *Masao Watanabe

Hiromichi Tanaka

Yasuhiro Inamura *Yuhua Su

Hiroyuki Asai

Masahide Harada *Ryota Komine

Yukiko Nagai

Tomokazu Aso *Hiroyuki Hasemi

Kenji Sakai *Seiko Kawamura *Takuya Okudaira

Tetsuya Kai *Rumi Shimizu *The Dang Vu

Hiroyuki Kogawa *Satoru Fujiwara *Wataru Kambara

Motoki Ooi *Motoyasu Adachi *Yoko Watanabe

Kentaro Suzuya *Shigeki Arai *Hideaki Takahashi

Mitsutaka Nakamura *Chie Shibazaki *Tomohiro Seya

Takashi Ino *Hiroshi Fujimori *Setsuo Sato

Naokatsu Kaneko *Shunsuke Makimura *Testuya Yokoo *Kaoru Taketani *Shuki Torii *Naritoshi Kawamura *<KEK>

Neutron Instrumentation Section

*: additional duties<JAEA>

174

Tatsuya Nakamura (Leader)

Ryuji Maruyama

Yukio Hishinuma

Kentaro Toh

Dai Yamazaki

Aoi Yanagi

Kaoru Sakasai

Tomokatsu Koizumi

MLF Operations in 2021

MLF Annual Report 2021

Muon Science Section

*: additional duties<KEK>
Ryosuke Kadono (Leader)

Yasuhiro Miyake

Hirotaka Okabe

Naritoshi Kawamura (Sub-Leader)

Yu OishiMotonobu Tanpo

Koichiro Shimomura *Yukinori Nagatani

Taihei Adachi

Akihiro Koda

Shiro Matoba

Amba Datt Pant

Patrick Strasser

Soshi Takeshita

Atsuko Irie

Takayuki Yamazaki

Izumi Umegaki

Hua Li

Sotaro Kanda

Hiroaki Natori

Shogo Doiuchi

Yutaka Ikedo

Shoichiro Nisimura

Akiko Hashimoto

Yasuo Kobayashi

Sourav Kumar Dey

Yoshinori Ito

Junpei Nakamura

Hiroshi Fujimori

Takashiro Yuasa

Masatoshi Hiraishi<JAEA>
Wataru Higemoto *Takashi Ito *175

MLF Operations in 2021

MLF Annual Report 2021

CROSS Staff 2021
Director

Mitsuhiro Shibayama

Science Coordinators
Shamoto Shinichi

Hibi Masaaki

Jun Sugiyama

Kazuhisa Kakurai

Midori Kamimura

Research & Development Division*: additional duties

Jun-ichi Suzuki (Head)<BL15 Group><Technical Support Group>

Kenichi Funakoshi (Deputy Head)

Kazuki Ohishi (Leader)

Yoshifumi Sakaguchi (Leader)

Tsukasa Miyazaki * (Deputy Head)

Jun-ichi Suzuki *Nobuo Okazaki (Leader)

Hiroki Iwase

Toshiaki Morikawa (Sub-Leader)

Yukihiko Kawamura

Koji Kiriyama *<BL01 Group>

Hiroshi Kira

Kazuya Kamazawa (Leader)
Kazuki Iida

<BL17 Group>

Motoyuki Ishikado

Kazuhiko Ikeuchi

Noboru Miyata (Leader)

Shuoyuan Zhang

Kazuhiro Akutsu

Hiroshi Arima

Takayasu Hanashima

Misaki Ueda

<BL02 Group>

Keiichi Ohuchi

Masato Matsuura (Leader)Takeshi Yamada<BL18 Group>

Masae Sahara

Taiki Tominaga

Akiko Nakao (Leader)

Yuukou Nojiri

Koji Munakata

Takayoshi Ito *Yoshihisa Ishikawa

Satoshi Kasai<BL11 Group>

Kentaro Moriyama

Kenichi Funakoshi * (Leader)
Jun Abe<BL22 Group>

Shinichi Machida

Hirotoshi Hayashida (Leader)

Yuuki Nagai

Joseph Don Parker
Yoshihiro Matsumoto

Safety Division

176*: additional duties

Mitsuhiro Shibayama * (Head)

Tazuko Mizusawa *Koji Kiriyama (Leader)

Masae Sahara *Yasuhiro YamaguchiMLF Operations in 2021

MLF Annual Report 2021

Utilization Promotion Division*: additional duties

Takashi Noma (Head)

Miho Igarashi

Nobuo Okazaki *Tsukasa Miyazaki * (Deputy Head)

Tomoko Ishikawa

Rie Kurosawa *Seiya Konishi (Leader)

Kaoru Ohuchi

Taeko Ishikawa

Takayoshi Ito (Leader)

Emi Goto

Kazuko Kanno

Toshiki Asai (Leader)

Tazuko Mizusawa

Hideyuki Niitsuma

Michihiko Murasawa (Head)

Rei Ito (Leader)

Shinobu Matsumoto

Takashi Hikita (Leader)

Tomoko Sakuma

Mami Uchida

Junichi Sato (Leader)

Mutsumi Shiraishi

Administration Division

Industrial Collaboration Promotion Division
Tsukasa Miyazaki (Head)

Jun Abe *Seiya Konishi (Leader)Takeshi Yamada *Noboru Miyata *Yoshihiro Matsumoto **: additional duties

Hiroki Iwase *177

MLF Operations in 2021

MLF Annual Report 2021

Ibaraki Neutron Beamline Staff in 2021

Ibaraki Prefectural Government<Senior Director for Neutron Promotion><Neutron Beamline Coordinator>

Hironori Kodama

Michiko Konno
Tetsuroh Minemura

Ibaraki University ** Trustee of the Beamline operations<BL03 iBIX Group><BL20 iMATERIA Group><Technical Support Group>

Katsuhiro Kusaka (Leader)

TToru Ishigaki (Leader)

Junichi Hiroki

Taro Yamada

Satoshi Koizumi

Tomoyuki Nakazawa

Naomine Yano

Akinori Hoshikawa

Mitsuyuki Fujii

Ichiro Tanaka

Shigeo Sato

Shinju Shibata

Takaaki Hosoya

Yusuke Onuki

Takumi Inada

Yohei Noda
Tomoki Maeda
Takeshi Matsukawa

178

MLF Operations in 2021

MLF Annual Report 2021

Proposals Review System, Committees and Meetings

Proposal Review System
The JAEA-KEK-CROSS Agreement of Coopera�on on the Promo�on of Public U�liza�onof the Speciﬁc Neutron Beam Facili�es at J-PARC (Enacted on 1 April 2011)
President
JAEA

Director General
KEK

J-PARC
Center(JAEA/KEK)

President
CROSS

Collabora�onCommi�ee

Director
J-PARCAll except Public Beamlines

Director
CROSS-Tokai

RegisteredIns�tu�on(CROSS)

Public Beamlines Only

Selec�on
Commi�ee

MLF Advisory
Board

Task Forces

Joint Mee�ng

All except Contract
Beamlines
Muon Instrument
Proposal Rev. Comm.

Muon Science
Proposal Rev. Comm.

All except Public
Beamlines

Public Beamlines Only

Neutron Science
Proposal Rev. Comm.

Proposal
Evalua�on Comm.

Contract Beamlines
Only

Neutron Instrument Contract Beamline
Proposal Rev. Comm. Evalua�on Comm.
Joint Mee�ng

Muon
Instrument
Proposals

Joint Mee�ng

Neutron Instrument
Proposals
Muon Program
Advisory Comm.

Muon Scien�ﬁc Proposals

Report the results to J-PARC
and CROSS-Tokai Directors

Public Beamlines Only
All except Public Beamlines
Neutron Program
JAEA Research
CROSS Development
Advisory
Proposal Advisory Proposal Evalua�on
Commi�eeCommi�ee
Panel
Joint Mee�ng

Neutron Scien�ﬁc Proposals

UniﬁedAccess Point

ALL Proposals submi�ed via the J-PARC Users Oﬃce
Figure 1. Proposals Review System Framework.

179

MLF Operations in 2021 MLF Annual Report 2021

Materials and Life Science Facility Advisory Board

Yoshie Otake

RIKEN

Tadashi Adachi

Sophia University

Toshiya Otomo

Kazuya Aizawa

Japan Atomic Energy Agency

High Energy Accelerator Research
Organization

Hiroshi Amitsuka

Hokkaido University

Yoshiharu Sakurai

Japan Synchrotron Radiation
Research InstituteTaka-hisa Arima(chair)The University of Tokyo

Taku Sato

Tohoku University

Masahiro Hino

Kyoto University

Koichiro Shimomura High Energy Accelerator Research
Organization

Shinich Itoh

High Energy Accelerator Research
Organization

Kazuhiko Soyama

Japan Atomic Energy Agency

Yasuhiro Iye

Chubu University

Yoko Sugawara

Toyota Physical and Chemical
Research Institute

Ryosuke KadonoHigh Energy Accelerator Research
Organization

Jun-ichi Suzuki

Comprehensive Research Organizationfor Science and Society

Takashi Kamiyama

Hokkaido University

Atsushi Takahara

Kyushu University

Yukinobu Kawakita

Japan Atomic Energy Agency

Masayasu Takeda

Japan Atomic Energy Agency

Hiroyuki Kishimoto

Sumitomo Rubber Industries, LTD.

Osamu Yamamuro

The University of Tokyo

Kenji Nakajima

Japan Atomic Energy Agency

Neutron Science Proposal Review Committee

Jun’ichiro Mizuki

Kwansei Gakuin University

Hiroshi Abe

National Defense Academy of Japan

Kenji Ohoyama

Ibaraki University

Taka-hisa Arima(chair)The University of Tokyo

Toyotaka Osakabe

Japan Atomic Energy Agency

Toshiya Otomo

Hiroyuki Kagi

The University of Tokyo

High Energy Accelerator Research
Organization

Ryosuke KadonoHigh Energy Accelerator Research
Organization

Hideki Seto

High Energy Accelerator Research
Organization

Yukinobu Kawakita

Japan Atomic Energy Agency

Naoya Torikai

Mie University

Masaaki Kitaguchi

Nagoya University

Noriyuki Tsuchida

University of Hyogo

Takatsugu Masuda

The University of Tokyo

Term: through September 30, 2021

Tsukasa Miyazaki

Comprehensive Research Organizationfor Science and Society

Muon Science Proposal Review Committee

180

Term: through March 31, 2023

Ryosuke KadonoHigh Energy Accelerator Research
Organization

Yukinobu Kawakita

Japan Atomic Energy Agency

Tadashi Adachi

Sophia University

Kenta Amemiya

High Energy Accelerator Research
Organization

Hidehito Asaoka

Japan Atomic Energy Agency

Toshiyuki Azuma

RIKEN

Katsuyuki Fukutani

The University of Tokyo

Wataru Higemoto

Japan Atomic Energy Agency

Takamitsu Kohzuma Ibaraki University

Adrian Hillier

Rutherford Appleton Laboratory

Kenya Kubo (chair)International Christian University

Katsuya Inoue

Hiroshima University

Roderick Macrae

Marian University

Shinichi Itoh

High Energy Accelerator Research
Organization

Tsutomu Mibe

High Energy Accelerator Research
Organization

Naritoshi Kawamura High Energy Accelerator Research
Organization
Yasushi Kino

Tohoku University

Akihiro Koda

High Energy Accelerator Research
Organization

MLF Annual Report 2021

MLF Operations in 2021

Yasuhiro Miyake

High Energy Accelerator Research
Organization

Koichiro Shimomura High Energy Accelerator Research
Organization

Chihiro OhmoriHigh Energy Accelerator Research
Organization

Yoko Sugawara

Kitasato University

Toshiya Otomo

High Energy Accelerator Research
Organization

Jun Sugiyama

Comprehensive Research Organizationfor Science and Society

Hideki Seto

High Energy Accelerator Research
Organization

Masaaki Sugiyama

Kyoto University

Tatsushi Shima

Osaka University

Toshiyuki Takayanagi Saitama University
Term: through March 31, 2021

Selection Committee

Yoshie Otake

RIKEN

Tadashi Adachi

Sophia University

Yoshiharu Sakurai

Hiroshi Amitsuka

Hokkaido University

Japan Synchrotron Radiation
Research InstituteTaka-hisa Arima(chair)The University of Tokyo

Taku Sato

Tohoku University

Yoko Sugawara

Masahiro Hino

Kyoto University

Toyota Physical and Chemical
Research InstituteYasuhiro Iye

Japan Society for Promotion of Science

Atsushi Takahara

Kyushu University

Takashi Kamiyama

Hokkaido University

Osamu Yamamuro

The University of Tokyo

Hiroyuki Kishimoto

Sumitomo Rubber Industries, LTD.

Term: through March 31, 2023

Proposal Evaluation Committee

Jun’ichiro Mizuki

Kwansei Gakuin University

Hiroshi Abe

National Defense Academy of Japan

Kenji Ohoyama

Ibaraki University

Taka-hisa Arima(chair)The University of Tokyo

Toshiya Otomo

High Energy Accelerator Research
Organization

Hiroyuki Kagi

The University of Tokyo

Naoya Torikai

Mie University

Masaaki Kitaguchi

Nagoya University

Noriyuki Tsuchida

University of Hyogo

Takatsugu Masuda

The University of Tokyo

Term: through September 30, 2021

Tsukasa Miyazaki

Comprehensive Research Organizationfor Science and Society

Neutron Advisory Committee (NAC)

Phillip King

Rutherford Appleton Laboratory

NAC convened online on 10 and 17 February 2022.

Toyohiko Kinoshita

Japan Synchrotron Radiation
Research Institute

Ken Anderson

Oak Ridge National Laboratory

Guenter Muhrer

European Spallation Source

Taka-hisa Arima

The University of Tokyo

Yoshie Otake

RIKEN

Christiane AlbaSimionesco

Laboratoire Léon Brillouin

Sungil Park

Korea Atomic Energy Research InstituteJamie Schulz (chair)

Bertrand Blau

Paul Scherrer Institut

Australian Nuclear Science andTechnology Organization

Michael Dayton

Oak Ridge National Laboratory

Jon Taylor

European Spallation Source

181

MLF Operations in 2021 MLF Annual Report 2021

182

Muon Advisory Committee (MAC)

Kenya Kubo

International Christian University

MAC convened online on 2, 7, 14 and 21 February 2022.

Andrew Macfarlane

The University of British Columbia

Martin Månsson

KTH Royal Institute of Technology

Nori Aoi

Osaka University

Tadayuki Takahashi

The University of Tokyo

Thomas Prokscha(chair)Paul Scherrer Institut

Hiroshi Amitsuka

Hokkaido University

Klaus Kirch

ETH Zurich and Paul Scherrer Institut

MLF Annual Report 2021

MLF Operations in 2021

Workshops, Conferences, Seminars and Schools in 2021

Conferences held jointly by J-PARC MLF and CROSS

Conferences held by KEK

2021 Meeting on J-PARC MLF Industrial Use

第 5 回文理融合シンポジウム “ 量子ビームで歴史を探る－加速器が紡ぐ文理融合の地平－ ”

15-16 Jul. 2021, Online

9 Sep. 2021, Online
Workshop with ANSTO on Mutual Cooperation in Field
第 6 回文理融合シンポジウム “ 量子ビームで歴史を探る－加速器が紡ぐ文理融合の地平－ ”

of Neutron Science
30 Jul. 2021, Online

7-8 Jan. 2022, Online, Osaka University, Toyonaka
2021 Z-Code Beginner Level Training Course
2-31 Aug. 2021, On-demandWorkshops held by KEK

2021 Z-Code Intermediate level Training Course

令和 3 年度物構研コロキウム 第 4 回“ 中性子で観る量子物質の準粒子構造 ”

1 Dec. 2021-28 Feb. 2022, On-demand

12 Jul. 2021, Onlineth2021 Quantum Beam Science Festa (The 13 MLF
thSymposium and the 39 PF Symposium)
7-9 Mar. 2022, Online

令和 3 年度物構研コロキウム 第 5 回“ ミュオンは超伝導の研究にどう役立ってきてどう役立って
いくか ”
13 Sep. 2021, Online
Analysis of ordered/disordered structure in functional
materials with high intensity neutron total scattering
technique (BL21)
16 Nov. 2021, Online
Study on Cross-correlated Physics by Polarized Neutron
Spectrometer, POLANO (BL23)
30 Nov. 2021, Online
Studies on Dynamics in Condensed Matters by using
the High Resolution Chopper Spectrometer (BL12)10 Dec. 2021, Online

Screenshot of Quantum Beam Science Festa(photo courtesy of J-PARC)

Study on slow dynamics by the neutron resonance spinecho spectrometers VIN ROSE (BL06)
15 Dec. 2021, Online

Conferences held by J-PARC MLF and otherorganizationsth

18 Korea-Japan Meeting on Neutron Science“Workshop on Neutron and Muon Methods for J-PARC
MLF Users in Korea”
30 Apr. 2021, Online

Fundamental Physics with Pulsed Cold Neutrons (BL05)
16-17 Dec. 2021, Nagoya University, Nagoya
Workshop on Neutron Powder Diffraction using
SuperHRPD (BL08)
17 Dec. 2021, Online

183

MLF Operations in 2021

MLF Annual Report 2021

Workshop on Neutron Powder Diffraction using SPICA(BL09)
20 Dec. 2021, Online
2021 年度物構研コロキウム 第 9 回“MLF 中性子回折・散乱装置による蓄電池材料研究の展開 ”
17 Jan. 2022, Online

Workshops and Seminars held by CROSS andother organizations

Screenshot of CROSSroads(photo courtesy of CROSS)rd

3 Joint Workshop for Complementary Use of Synchrotron
Radiation and Neutrons “Small-angle Neutron scatteringthmeasurement”

4 Joint Workshop for Complementary Use of Synchrotron

9 Apr. 2021, MLF, IBARAKI Quantum Beam Research Center,

Radiation and Neutrons

Tokai“Neutron Powder Diffraction Measurement”
18 Nov. 2021, JRR-3, IBARAKI Quantum Beam ResearchWorkshop on Battery Materials

Center, Tokai

10 Jun. 2021, Online
Workshop on Organic materials and Polymers
Workshop on Organic materials and Polymers“ 有機・高分子材料への小角散乱解析法の展開 ”（第 2 回）
3 Aug. 2021, Online
第 1 回中性子産業応用セミナー
13 and 27 Sep. 2021, Onlineth7 Symposium on the Collaborative Use of Large Research“ 有機・高分子材料への小角散乱解析法の展開 （” 第 3 回）
25 Jan. 2022, Online
2021 年度 磁性材料研究会
16 Feb. 2022, Online
ものづくり基盤研究会“ －内部応力・ひずみ測定を様々な材料で考える－ ”
10 Mar. 2022, Online

Institutions and the Super Computer
14 Sep. 2021, Online

2021 Workshop on Liquids and Amorphous Materials
11 Mar. 2022, Online

2021 Neutron experiment technique training course
21 Oct. 2021, Online

2021 Workshop on Structural Biology

CBI 研究機構 量子構造生命科学研究所 中性子産業利用“ タンパク質科学・構造生物学と創薬への展開 ”
15 Mar. 2022, Online

推進協議会 生物・生体材料研究会 合同シンポジウム“ 生体分子の動的挙動解析への挑戦 試料調整から解析まで ”
29 Oct. 2021 and 4 Mar. 2022, OnlinethThe 25 CROSSroads Workshop“ データ解析ソフトウェアの紹介 ”
15 Nov. 2021, Online

184

第 75 回 SPring-8 先端利用技術ワークショップ / 第 1 回
放射光・中性子連携利用研究会
25 Mar. 2022, Online

Workshops and Seminars held by Ibaraki
Neutron Beamline and other organizations
iBIX タンパク質構造研究会
20 Aug. 2021, Online

MLF Annual Report 2021

MLF Operations in 2021st

2021 1 Workshop on iMATERIA
23 Aug. 2021, Onlinend2021 2 Workshop on iMATERIA
21 Sep. 2021, Onlinerd2021 3 Workshop on iMATERIA
1 Oct. 2021, Onlineth2021 4 Workshop on iMATERIA
21 Dec. 2021, Onlineth2021 5 Workshop on iMATERIA
11 Jan. 2022, Online
2021 年度 iBIX JAXA KEK 物構研 QST 合同タンパク質研究会
16 Feb. 2022, Onlinestth2021 1 (29 ) Workshop on iBIX
24 Feb. 2022, Onlineth2021 6 Workshop on iMATERIA

Screenshot of Neutron and Muon School(photo courtesy of CROSS)

15 Mar. 2022 Online

Schools in 2021
Hello Science from J-PARC“Seeing with Muons”

Hello Science from J-PARC“Muon H Line Finally Starts Operation”
24 Dec. 2021, IBARAKI Quantum Beam Research Center,

30 Jul. 2021, Online

Tokai

Hello Science from J-PARC“Neutrons for Finding Hydrogen”
29 Oct. 2021, IBARAKI Quantum Beam Research Center,
Tokai
th

KEK-IINAS School The 5 Neutron and Muon School
6-9 Dec. 2021, Online

185

MLF Operations in 2020

MLF Annual Report 2021

Award List
Dept. of Chem Chair Award for the best B.Sc
presentation, The University of Tokyo
Exploring hydrogen-ordered counter polymorph of ice IV byin-situ neutron/X-ray diffraction and Raman spectroscopy
H. Kobayashi (2022-03-25)
The JSNS Poster Prize
Measurement of Neutron Nuclear Scattering Length using
Pulsed Neutron Interferometer
T. Fujiie (2021-12-02)
The JSNS Science Prize
Application and development of neutrons on soft matterscience
H. Seto (2021-12-01)
The JSNS Technology Prize
Development of Metal Substrates for Neutron-focusing
Supermirrors
T. Hosobata, Y. Yamagata (2021-12-01)

SPSJ Publicity Award
Distinguishing Adsorbed and Deposited Ionomers in
the Catalyst Layer of Polymer Electrolyte Fuel Cells using
Contrast Variation Small-angle Neutron Scattering
M. Harada, S. Takata, H. Iwase, S. Kajiya, H. Kadoura,
T. Kanaya (2021-08-18)
The First Prize in the Best Paper on Materials, Hong
Kong Institution of Engineers
Cooperative deformation in high-entropy alloys at ultralow
temperatures
M. Naeem (2020-12)
Kyushu Analytical Chemistry Award 2020
Mixing States and Properties of Reaction Fields for Binary
Solvents Studied by Small-Angle Neutron Scattering
T. Takamuku (2020-11-06)
The 60th Harada Young Research Award, The Honda
Memorial Foundation
金属積層造形における組織形成と特性制御への応用

The FY2021 Research Award, The Crystallographic
Society of Japan
Structural & Chemical Study of Molecular Crystals basedon Precise Positions of Hydrogen Atoms by Single-crystal
Neutron Diffraction
T. Ohhara (2021-11-20)
The 55th Paper Award, Japan Institute of Copper
Characterization of Precipitated Phase in Cu-Ni-Si Alloyby Small Angle X-ray Scattering, Small Angle Neutron
Scettering and Atom Probe Tomography
H. Sasaki, S. Akiya, Y. Oba, M. Onuma, A. D. Giddings,
T. Ohkubo (2021-10-23)
The 50th Young Scientist Presentation Award, The
Japan Society of Applied Physics
Observation of spontaneous vortices in superconductor/
ferromagnet nanocomposites
N. Teramachi, (2021-09-21)
MSJ Presentation Award for Student
Magnetization analysis of hollow Fe 3O 4 particles bypolarized small angle neutron scattering
E. Nomura (2021-08-27)

186

K. Yamanaka (2020-07-03)
JSNS: The Japanese Society for Neutron Science
MSJ: The Magnetics Society of JapanSPSJ: The Society of Polymer Science, Japan

MLF Annual Report 2021

MLF Operations in 2021

MLF Publication 2021
1

W. Saito, K. Hayashi, Z. Huang, K. Sugimoto, K. Ohoyama, N.
Happo, M. Harada, K. Oikawa, Y. Inamura, K. Hayashi, T. Miyazaki, Y.
Miyazaki
Chemical-Pressure-Induced Point Defects Enable Low Thermal
Conductivity for Mg2Sn and Mg2Si Single Crystals
ACS Appl. Energy Mater., 4 5123-5131 (2021).

2

S. Uenuma, K. Endo, N. L. Yamada, H. Yokoyama, and K. Ito
Polymer Brush Formation Assisted by Hierarchical Self-Assembly of
Topological Supramolecule
ACS Appl. Mater. Interfaces, 13 60446-60453 (2021).

3

K. Nakashima, K. Onagi,Y. Kobayashi, T. Ishigaki, Y. Ishikawa, Y.
Yoneda, S. Yin, M. Kakihana, T. Sekino
Stabilization of Size-Controlled BaTiO 3 Nanocubes via Precise
Solvothermal Crystal Growth and Their Anomalous Surface
Compositional Reconstruction
ACS Omega, 6 9410 (2021).

45

M. Harada, S. Takata, H. Iwase, S. Kajiya, H. Kadoura, T. Kanaya
Distinguishing adsorbed and deposited ionomers in the catalyst
layer of polymer electrolyte fuel cells using contrast variation smallangle neutron scattering
ACS Omega, 6 15257-15263 (2021).
K. Chino
Multinetwork Elastomer Using Covalent Bond, Hydrogen Bond, andClay Plane BondACS Omega, 6 31168-31176 (2021).

6

Q. Li, Z. Deng, Y. Onuki, W. Wang, L. Li, Q. Sun
In-plane low thermal expansion of NiTi via controlled cross rolling
Acta Mater., 204 116506 (2021).

7

M. M. Nygård, Ø. S. Fjellvåg, M. H. Sørby, K. Sakaki, K. Ikeda, J.
Armstrong, P. Vajeeston, W. A. Sławiński, H. Kim, A. Machida, Y.
Nakamura, B. C.Hauback
The average and local structure of TiVCrNbDx (x = 0, 2.2, 8) from total
scattering and neutron spectroscopy
Acta Mater., 205 116496 (2021).

Müller-Buschbaum, L. D. Söderberg, S. V. Roth
Humidity-induced Nanoscale Restructuring in PEDOT:PSS andCellulose reinforced Bio-based Organic Electronics
Adv. Electron. Mater., 7 2100137 (2021).
13

M. Kawasaki, J.-K. Han, X. Liu, Y. Onuki, Y. O. Kuzminova, S. A.
Evlashin, A. M. Pesin, A. P. Zhilyaev, K.-D. Liss
In-situ heating neutron- and X-ray diffraction analyses for revealing structural evolution during post-printing treatments of additivemanufactured 316L stainless steel
Adv. Eng. Mater., 2100968 (2021).

14

N. Hisano, T. Sakamaki, T. Ohashi, K. Funakoshi, Y. Higo, Y. Shibazaki,
A. Suzuki
Elastic properties and structures of pyrope glass under high pressures
Am. Mineral., 106 7 (2021).

15

S. Kumar, D. Saha, S. Takata, V.K. Aswal, H. Seto
Modifications in the nanoparticle-protein interactions for tuning theprotein adsorption and controlling the stability of complexes
Appl. Phys. Lett., 118 153701 (2021).

16

P. Wu, J. Song, X. Yu, Y. Wang, K. Xia, B. Hong, L. Zu, Y. Du, P. Vallobra,
F. Liu, S. Torii, T. Kamiyama, Y. Xiong, W. Zhao
Evidence of Spin Reorientation and Anharmonicity in Kagome
Ferromagnet Fe3Sn2
Appl. Phys. Lett., 119 082401 (2021).

17

M. Naeem, H. Zhou, H. He, S. Harjo, T. Kawasaki, S. Lan, Z. Wu, Y.
Zhu, X-L. Wang
Martensitic transformation in CrCoNi medium-entropy alloy at cryogenic temperatureAppl. Phys. Lett., 119 131901 (2021).

18

R. Aggarwal, B. P. Lamichhane, M. H. Meylan, C. M. Wernsrich
An Investigation of Radial Basis Function Method for Strain
Reconstruction by Energy-Resolved Neutron Imaging
Appl. Sci., 11 391 (2021).

19

K. Ikeda, F. Fujisaki, T. Otomo, H. Ohshita, T. Honda, T. Kawamata,
H. Arima, K. Sugiyama, H. Abe, H. Kim, K. Sakaki, Y. Nakamura, A.
Machida, T. Sato, S. Takagi, S. Orimo
Generating Mechanism of Catalytic Effect for Hydrogen Absorption/
Desorption Reactions in NaAlH4–TiCl3
Appl. Sci., 11 8349 (2021).

8

Q. Li, Y. Onuki, Q. Sun
Tailoring thermal expansion of shape memory alloys through designed reorientation deformation
Acta Mater., 218 117201 (2021).

9

M. Naeem, H. He, S. Harjo, T. Kawasaki, W. Lin, J-J. Kai, Z. Wu, S. Lan,
X-L. Wang
Temperature-dependent hardening contributions in CrFeCoNi highentropy alloy
Acta Mater., 221 117371 (2021).

20

H. Nakagawa, T. Saio, M. Nagao, R. Inoue, M. Sugiyama, S. Ajito, T.
Tominaga, Y. Kawakita
Conformational dynamics of a multi-domain protein by neutron
scattering and computational analysis
Biophys. J., 120 3341-3354 (2021).

10

M. Busi, N. Kalentics, M. Morgano, S. Griffiths, A. S. Tremsin, T.
Shinohara, R. Logé, C. Leinenbach, M. Strobl
Nondestructive characterization of laser powder bed fusion parts
with neutron Bragg edge imaging
Additive Manufacturing, 39 101848 (2021).

21

Y. Kameda, K. Tsutsui, Y. Amo, T. Usuki, K. Ikeda, T. Otomo
Direct Observation of Scattering Angle Dependence of the
Inelasticity Effect on the Interference Term Obtained from Time-ofFlight Neutron Diffraction Experiments
Bull. Chem. Soc. Jpn., 94 2800 (2021).

11

A. S. Tremsin, Y. Gao, A. Makinde, H. Z. Bilheux, J. C. Bilheux, K. An,
T. Shinohara, K. Oikawa
Monitoring residual strain relaxation and preferred grain orientationof additively manufactured Inconel 625 by in-situ neutron imaging
Additive Manufacturing, 46 102130 (2021).

22

N. Nishi, J. Uchiyashiki, T. Oda, M. Hino, N. L. Yamada
Overscreening Induced by Ionic Adsorption at the Ionic Liquid/Electrode Interface Detected Using Neutron Reflectometry with a
Rational Material Design
Bull. Chem. Soc. Jpn., 94 2914-2918 (2021).

12

C. J. Brett, O. K. Forslund, E. Nocerino, L. P. Kreuzer, T. Widmann,
L. Porcar, N. L. Yamada, N. Matsubara, M. Månsson, P.

23

S. Klotz, B. Baptiste, T. Hattori, S.M. Feng, Ch. Jin, K. Béneut, J.M.
Guigner, I. Estève

187

MLF Operations in 2021

MLF Annual Report 2021

Synthesis and characterisation of a new graphitic C-S compound byhigh pressure decomposition of CS2
Carbon, 185 491-500 (2021).

188

24

S. Yamazoe, A. Yamamoto, S. Hosokawa, R. Fukuda, K. Hara, M.
Nakamura, K. Kamazawa, T. Tsukuda, H. Yoshida, T. Tanaka
Identification of hydrogen species on Pt/Al2O3 by in situ inelastic neutron scattering and their reactivity with ethylene
Catal. Sci. Technol., 11 116-123 (2021).

25

S. Behara, K. Ikeda, T. Thomas
Amphoteric behavior of Dy3+ in Na0.5Bi0.5TiO3: neutron diffraction and
Raman studies
Ceram. Int., 47 12870 (2021).

26

K. Fukui, S. Iimura, J. Wang, T. Tada, T. Honda, K. Ikeda, T. Otomo, H.
HosonoStabilization Factor of Anion-Excess Fluorite Phase for Fast Anion
Conduction
Chem. Mater., 33 1867-1874 (2021).

27

M. Nakamura, H. Watanabe, H. Akamatsu, K. Fujii, M. Yashima, G.
Hasegawa, M. Inada, K. Hayashi, K. Maeda
Sn-Based Perovskite with a Wide Visible Light Absorption Band
Assisted by Hydride Doping
Chem. Mater., 33 3631-3638 (2021).

28

Y. Kitagawa, J. Ueda, K. Fujii, M. Yashima, S. Funahashi, T. Nakanishi,
T. Takeda, N. Hirosaki, K. Hongo, R. Maezono, S. Tanabe
Site-Selective Eu3+ Luminescence in the Monoclinic Phase of YSiO2N
Chem. Mater., 33 8873-8885 (2021).

29

Y. Yano, T. Ono, T. Ohhara, Y. Hisaeda
Insights into Proton Dynamics in a Photofunctional Salt-Cocrystal
Continuum: Single-Crystal X-ray, Neutron Diffraction, and Hirshfeld
Atom Refinement
Chemistry - A European Journal, 27 17802-17807 (2021).

30

T.-N. Lam, M.-Y. Luo, T. Kawasaki, S. Harjo, J. Jain, S.-Y. Lee, A.-C. Yeh,
E.-W. Huang
Tensile Response of As-Cast CoCrFeNi and CoCrFeMnNi High-Entropy
AlloysCrystals, 12 157 (2021).

31

T. Matsukawa, K. Iida, M. Nakamura, T. Ishigaki
Detection of hydroxyl and hydride functional groups in a ceria crystal under hydrogen reduction
CrystEngComm, 23 2355-2359 (2021).

32

H. Yukawa, S. Watanabe, A. Suzuki, Y. Matsumoto, H. Araki, M.
Mizuno, K. Sugita, W. Higemoto
Temperature dependence of hydrogen solubility and diffusivity inhydrogen permeable membrane of pd-cu alloy with b2-type crystal
structure
Defect and Diffusion Forum, 407 31 (2021).

33

T. Katabuchi, Y. Toh, M. Mizumoto, T. Saito, K. Terada, A. Kimura, S.
Nakamura, H. Minghui, G. Rovira, M. IgashiraDiscovery of a new low energy neutron resonance of 89Y
Eur. Phys. J. A Hadron. Nucl., 57 4 (2021).

34

Y. Fujii, T. Tominaga, D. Murakami, M. Tanaka, H. Seto
Local Dynamics of the Hydration Water and Poly(Methyl
Methacrylate) Chains in PMMA Networks
Frontiers in Chemistry, 9 728738 (2021).

35

T. Yamashita, K. Okutsu, Y. Kino, R. Nakashima, K. Miyashita, K.
Yasuda, S. Okada, M. Sato, T. Oka, N. Kawamura, S. Kanda, K.
Shimomura, P. Strasser, S. Takeshita, M. Tampo, S. Doiuchi, Y.
Nagatani, H. Natori, S. Nishimura, A. D. Pant, Y. Miyake, K. Ishida
Time evolution calculation of muon catalysed fusion: Emission of recycling muons from a two-layer hydrogen film

Fusion Engineering and Design, 169 11258 (2021).
36

K. Okutsu, T. Yamashita, Y. Kino, R. Nakashima, K. Miyashita, K.
Yasuda, S. Okada, M. Sato, T. Oka, N. Kawamura, S. Kanda, K.
Shimomura, P. Strasser, S. Takeshita, M. Tampo, S. Doiuchi, Y.
Nagatani, H. Natori, S. Nishimura, A. D. Pant, Y. Miyake, K. Ishida
Design for detecting recycling muon after muon-catalyzed fusion
reaction in solid hydrogen isotope target
Fusion Engineering and Design, 170 112712 (2021).

37

N. Kawamura, S. Matoba, S. Makimura, M. Hara, Y. Hatano
Tritium behavior in isotropic graphite at room temperature
Fusion Engineering and Design, 172 112801 (2021).

38

J. Tang, T. Katashima, X. Li, Y. Mitsukami, Y. Yokoyama, U.-i. Chung,
M. Shibayama, T. Sakai
Effect of Nonlinear Elasticity on the Swelling Behaviors of Highly
Swollen Polyelectrolyte Gels
Gels, 7 25 (2021).

39

Y. Tsuji, M. Shibayama, X. Li
Neutralization and Salt Effect on the Structure and Mechanical
Properties of Polyacrylic Acid Gels under Equivolume Conditions
Gels, 7 69 (2021).

40

A. Sano-Furukawa, S. Kakizawa, C. Shito, T. Hattori, S. Machida, J.
Abe, K. Funakoshi, H. Kagi
High-pressure and high-temperature neutron-diffraction experiments using Kawai-type multi-anvil assemblies
High Press. Res., 41 65 (2021).

41

T. Okumura, T. Azuma, D. A. Bennett, P. Caradonna, I. Chiu, W.
B. Doriese, M. S. Durkin, J. W. Fowler, J. D. Gard, T. Hashimoto, R.
Hayakawa, G. C. Hilton, Y. Ichinohe, P. Indelicato, T. Isobe, S. Kanda,
M. Katsuragawa, N. Kawamura, Y. Kino, K. Mine, Y. Miyake, K. M.
Morgan, K. Ninomiya, H. Noda, G. C. O’Neil, S. Okada, K. Okutsu,
T. Osawa, N. Paul, C. D. Reintsema, D. R. Schmidt, K. Shimomura, P.
Strasser, H. Suda, D. S. Swetz, T. Takahashi, S. Takeda, S. Takeshita,
H. Tatsuno, Y. Ueno, J. N. Ullom, S. Watanabe, S. Yamada
Dynamical Response of Transition-Edge Sensor Microcalorimeters toa Pulsed Charged-Particle BeamIEEE Trans. Appl. Supercond., 31 2101704 (2021).

42

H. Shishido, K. Nishimura, T. D. Vu, K. Aizawa, K. M. Kojima, T.
Koyama, K. Oikawa, M. Harada, T. Oku, K. Soyama, S. Miyajima, M.
Hidaka, S. Y. Suzuki, M. M. Tanaka, S. Kawamata, T. IshidaHigh Spatial Resolution Neutron Transmission Imaging Using a
Superconducting Two-Dimensional Detector
IEEE Trans. Appl. Supercond., 31 2400505 (2021).

43

T. Oda, T. Arai, T. Furukawa, M. Shiraishi, Y. Sasajima
Electric-Field-Dependence Mechanism for Cosmic Ray Failure inPower Semiconductor Devices
IEEE Trans. Electron Devices, 68 3505 (2021).

44

T. Kato, M. Tampo, S. Takeshita, H. Tanaka, H. Matsuyama, M.
Hashimoto, Y. Miyake
Muon-Induced Single-Event Upsets in 20-nm SRAMs: Comparative
Characterization with Neutrons and Alpha Particles
IEEE Trans. Nucl. Sci., 68 1436 (2021).

45

S. Yamamoto, K. Ninomiya, N. Kawamura, T. Yabe, Y. Hirano
Three dimensional (3D) optical imaging system of muon beams using a silver activated zinc sulfide (ZnS(Ag)) sheet combined with amirrorIEEE Trans. Nucl. Sci., 68 2748 (2021).

46

Y. Iwamiya, M. Kawai, D. Nishio-Hamane, M. Shibayama, Z. Hiroi
Modern alchemy: Making “plastics” from paper
Ind. Eng. Chem. Res., 60 355-360 (2021).

47

D. Urushihara, T. Asaka, K. Fukuda, M. Nakayama, Y. Nakahira, C.

MLF Annual Report 2021

Moriyoshi, Y. Kuroiwa, O. K. Forslund, N. Matsubara, M. Månsson,
K. Papadopoulos, Y. Sassa, K. Ohishi, J. Sugiyama, Y. Matsushita, H.
Sakurai
Structural Transition with a Sharp Change in the Electrical Resistivity
and Spin-Orbit Mott Insulating State in a Rhenium Oxide, Sr3Re2O9
Inorg. Chem., 60 507 (2021).
48

S. Nakano, A. Sano-Furukawa, T. Hattori, S. Machida, K. Komatsu,
H. Fujihisa, H. Yamawaki, Y. Gotoh, T. Kikegawa
Observation of dihydrogen bonds in high-pressure phases of ammonia borane by X-ray and neutron diffraction measurements
Inorg. Chem., 60 3065-3073 (2021).

49

H. Kwon, E. Pietrasiak, T. Ohhara, A. Nakao, B. Chae, C.-C. Hwang, D.
Jung, I.-C. Hwang, Y. H. Ko, K. Kim, E. Lee
Programmable Synthesis of Silver Wheels
Inorg. Chem., 60 6403-6409 (2021).

50

K. Kimura, N. Yagi, S. Hasegawa, M. Hagihala, A. Miyake, M.
Tokunaga, H. Cao, T. Masuda, T. Kimura
Coexistence of Magnetoelectric and Antiferroelectric-like Orders in
Mn3Ta2O8
Inorg. Chem., 60 15078-15084 (2021).

51

Y. Zhang, J. Brorsson, T. Kamiyama, T. Saito, P. Erhart, A. E. C.
Palmqvist
Investigating the Chemical Ordering in Quaternary Clathrate
Ba8AlxGa16–xGe30
Inorg. Chem., 60 16977-16985 (2021).

52

53

54

55

56

57

58

59

S. Tajima, N. Ohba, A. Suzumura, S. Kajita
Synthesis and Ion-Transport Properties of EuKGe2O6-, Ca3Fe2Ge3O12- ,and BaCu2Ge2O7‑Type Oxide-Ion Conductors
Inorg. Chem., 60 17019-17032 (2021).
S. Nogami, K. Kadota, H. Uchiyama, H. Arima-Osonoi, H. Iwase, T.
Tominaga, T. Yamada, S. Takata, M. Shibayama, Y. Tozuka
Structural changes in pH-responsive gelatin/hydroxypropyl methylcellulose phthalate blends aimed at drug-release systems
Int. J. Biol. Macromol., 190 989 (2021).
X. X. Zhang, D. Knoop, H. Andrä, S. Harjo, T. Kawasaki, A. Lutz, M.
LahresMultiscale constitutive modeling of additively manufactured Al-SiMg alloys based on measured phase stresses and dislocation density
Int. J. Plast., 140 102972 (2021).
N. Ishida, T. Tajima, N. Kitamura, Y. IdemotoSingle-phase synthesis, average, electronic, and local structure andcathode properties of pyroxene type LiFeSi2O6
Ionics, 27 925-933 (2021).
Y. Takayama, Y. Xu, T. Yoshida, H. Tanaka, Y. Onuki, S. Sato
Texture evolutions in aluminum and Al-3%Mg alloy subjected toshear deformation and subsequent annealing
IOP Conf. Ser. Mater. Sci. Eng., 1121 12017 (2021).
N. Tsuchida, E. Ishimaru, M. Kawa
Role of Deformation-Induced Martensite in TRIP Effect of Metastable
Austenitic Steels
ISIJ International, 61 556-563 (2021).
N. Tsuchida, R. Ueji, T. Inoue
Effect of Temperature on Stress–Strain Curve in SUS316L Metastable
Austenitic Stainless Steel Studied by In Situ Neutron Diffraction
Experiments
ISIJ International, 61 632-640 (2021).
S. Harjo, T. Kawasaki, N. Tsuchida, S. Morooka, W. Gong
Relation between Intergranular Stress of Austenite and Martensitic
Transformation in TRIP Steels Revealed by Neutron Diffraction
ISIJ International, 61 648-656 (2021).

MLF Operations in 2021

60

H. Sato, M. Sato, Y. Su, T. Shinohara, T. Kamiyama
Improvement of Bragg-edge Neutron Transmission Imaging for
Evaluating the Crystalline Phase Volume Fraction in Steel Composedof Ferrite and Austenite
ISIJ International, 61 1584-1593 (2021).

61

R. Kataoka, M. Nozaki, T. Kimura, K. Sakaki, T. Kojima, K. Ikeda, T.
Otomo, N. Takeichi, A. Kamegawa
Zirconium Hydride-Stabilized Yttrium Hydride (ZSY): Stabiliza- tionof a Face-Centered Cubic YH3 Phase by Zr Substitution
J. Alloys. Compd., 851 156071 (2021).

62

K. D. Liss, S. Harjo, T. Kawasaki, K. Aizawa, P. Xu
Anisotropic thermal lattice expansion and crystallographic structureof strontium aluminide within Al-10Sr alloy as measured by in-situ
neutron diffraction
J. Alloys. Compd., 869 159232 (2021).

63

K. Maruyama, S. Tanaka, S. Natori, I. Bizen, K. Amemiya, R.
Kiyanagi, A. Nakao, K. Moriyama, Y. Ishikawa, Y. Amako, T. Iiyama,
R. Futamura, S. Utsumi
Magnetic phase diagram of helimagnetic Ba(Fe1-xScx)12O19(0 ≤x≤0.2)
hexagonal ferrite
J. Alloys. Compd., 892 162125 (2021).

64

X. X. Zhang, A. Lutz, H. Andrä, M. Lahres, W. Gong, S. Harjo, C.
Emmelmann
Strain hardening behavior of additively manufactured and annealed AlSi3.5Mg2.5 alloy
J. Alloys. Compd., 898 162890 (2021).

65

T. Okudaira, Y. Ueda, K. Hiroi, R. Motokawa, Y. Inamura, S. Takata, T.
Oku, J. Suzuki, S. Takahashi, H. Endo, H. Iwase
Polarization analysis for small-angle neutron scattering with a 3He
spin filter at a pulsed neutron source
J. Appl. Crystallogr., 54 1-9 (2021).

66

D. Miura, T. Kumada, Y. Sekine, R. Motokawa, H. Nakagawa, Y. Oba,
T. Ohhara, S. Takata, K. Hiroi, T. Morikawa, Y. Kawamura, K. Ohishi,
J. Suzuki, Y. Miyachi, T. Iwata
Development of spin-contrast-variation neutron powder diffractometry for extracting the structure factor of hydrogen atoms
J. Appl. Crystallogr., 54 454-460 (2021).

67

M. Mizusawa, K. Sakurai
2D real space visualization of d values in polycrystalline bulk materials of different hardness
J. Appl. Crystallogr., 54 597 (2021).

68

T. Tominaga, M. Sahara, Y. Kawakita, H. Nakagawa, T. Yamada
Evaluation of sample cell materials for aqueous solutions used inquasi-elastic neutron scattering measurements
J. Appl. Crystallogr., 54 1631-1640 (2021).

69

H. Singh, V.K. Aswal
Tuning of micelle adsorption on nanoparticles by combination of
surfactants
J. Appl. Phys., 129 234703 (2021).

70

R. Maruyama, D. Yamazaki, H. Aoki, K. Akutsu-Suyama, T.
Hanashima, N. Miyata, K. Soyama, T. Bigault, T. Saerbeck, P.
Courtois
Improved performance of wide bandwidth neutron-spin polarizer
due to ferromagnetic interlayer exchange coupling
J. Appl. Phys., 130 083904 (2021).

71

J. G. Nakamura, Y. Kawakita, K. Shimomura, T. Suemasu
Hydrogen impurities in p-type semiconductors, GeS and GeTe
J. Appl. Phys., 130 195701 (2021).

72

N. Sato, R. Yogo ,S. Yanaka, A. Martel, L. Porcar, K. Morishima, R.
Inoue, T. Tominaga, T. Arimori, J. Takagi, M. Sugiyama, K. Kato189

MLF Operations in 2021

MLF Annual Report 2021

A feasibility study of inverse contrast-matching small-angle neutron
scattering method combined with size exclusion chromatographyusing antibody interactions as model systems
J. Biochem., 169 701-708 (2021).
73

74

75

76

77

190

E. Y. Kozhunova, V. Y. Rudyak, X. Li, M. Shibayama, G. S. Peters, O. V.
Vyshivannaya, I. R. Nasimova, A. V. Chertovich
Microphase separation of stimuli-responsive interpenetrating network microgels investigated by scattering methods
J. Colloid Interface Sci., 597 297 (2021).
H. Arima-Osonoi, K. Yamazaki, R. Simura, T. Sugawara, K. Yubuta, K.
Sugiyama, A. Yoshiasa
Local structure investigations of Sn and Mn doped in β-Ga2O3 by
X-ray absorption spectroscopy
J. Cryst. Growth, 570 126223 (2021).
R. Yuge, S. Kuroshima, M. Tabuchi, K. Doumae, H. Shibuya
Charge Compensation Mechanism and Structural Change of Li- Rich
Layered Oxide Li1.23Mn0.46Fe0.15Ni0.15O2 Electrode during Charging andDischarging
J. Electrochem. Soc., 168 040518 (2021).
N. V. Mdlovu, K.-S. Lin, M.-T. Weng, C.-C. Hsieh, Y.-S. Lin, M. J. C.
Espinoza
In vitro intracellular studies of pH and thermo-triggered doxorubicinconjugated magnetic SBA-15 mesoporous nanocarriers for anticancer activity against hepatocellular carcinoma
J. Ind. Eng. Chem., 102 1 (2021).
J. Koga, S. Ieki, A. Kimura, M. Kitaguchi, R. Kitahara, K. Mishima, N.
Nagakura, T. Okudaira, H. Otono, H. M. Shimizu, N. Sumi, S. Takada,T. Tomita, T. Yamada, T. Yoshioka
Measurement of γ rays from 6LiF tile as an inner wall of a neutrondecay detector
J. Instrum., 16 P02001 (2021).

78

S. Yamamoto, K. Ninomiya, N. Kawamura, Y. Hiran
Optical imaging of decayed positrons and muons with different
collimators
J. Instrum., 16 P08062 (2021).

79

T. Yajima, Y. Hinuma, S. Hori, R. Iwasaki, R. Kanno, T. Ohhara, A.
Nakao, K. Munakata, Z. Hiroi
Correlated Li-ion migration in the superionic conductor Li10GeP2S12J. Mater. Chem. A, 9 11278-11284 (2021).

80

T. Kato, Y. Yamada, Y. Nishikawa, T. Otomo, H. Sato, S. Sato
Origins of peaks of graphitic and pyrrolic nitrogen in N1s X-ray photoelectron spectra of carbon materials: quaternary nitrogen, tertiaryamine, or secondary amine?
J. Mater. Sci., 56 15798–15811 (2021).

81

G. Yamamoto, A. Kyono, J. Abe, A. Sano-Furukawa, T. Hattori
Crystal structure of nesquehonite, MgCO3·3H(D)2O by neutron diffraction and effect of pH on structural formulas of nesquehonite
J. Mineral. Petrol. Sci., 116 96 (2021).

82

Y. Mori, H. Kagi, S. Kakizawa, K. Komatsu, C. Shito, R. Iizuka-Oku, K.
Aoki, T. Hattori, A. Sano-Furukawa, K. Funakoshi, H. Saitoh
Neutron diffraction study of hydrogen site occupancy in Fe0.95Si0.05 at
14.7 GPa and 800K.
J. Mineral. Petrol. Sci., 116 309-313 (2021).

83

H. AbePhase variety in ionic liquids: Hydrogen bonding and molecularconformations
J. Mol. Liq., 332 115189 (2021).

84

S. Hashimoto, K. Nakajima, T. Kikuchi, K. Kamazawa, K. Shibata, T.
YamadaExperimental analysis on dynamics of liquid molecules adjacent toparticles in nanofluids
J. Mol. Liq., 342 117580 (2021).
85

H. Abe, F. Nemoto, K. Hiroi, K. Ohishi, S. Takata
Spontaneous formations of nanoconfined water in ionic liquids bysmall-angle neutron scattering
J. Mol. Liq., 346 117035 (2021).

86

K. Shimada-Takaura, K. Ninomiya, A. Sato, N. Ueda, M. Tampo, S.
Takeshita, I. Umegaki, Y. Miyake, K. Takahashi
A novel challenge of nondestructive analysis on OGATA Koan’s sealed
medicine by muonic X-ray analysis
J. Nat. Med., 75 532–539 (2021).

87

M. Arai, K. H. Andersen, D. N. Argyriou, W. Schweika, L. Zanini, S.
Harjo, T. Kamiyama, M. Harada
The performance of neutron diffractometers at long and short pulse
spallation sources: Comparison between ESS and J-PARC
J. Neutron Res., 23 215-232 (2021).

88

H. Watanabe, N. Arai, E. Nozaki, J. Han, K. Fujii, K. Ikeda, T. Otomo,
K. Ueno, K. Dokko, M. Watanabe, Y. Kameda, Y. Umebayashi
Local Structure of Li+ in Super-concentrated Aqueous LiTFSA
SolutionsJ. Phys. Chem. B, 125 7477 (2021).

89

Y. Kameda, M. Kowaguchi, K. Tsutsui, Y. Amo, T. Usuki, K. Ikeda, T.
Otomo
Experimental Determination of Relationship between Intramolecular
O-D Bond Length and Its Stretching Vibrational Frequency of D2O
Molecule in the Liquid State
J. Phys. Chem. B, 125 11285-11291 (2021).

90

T. Takamuku, A. Tashiro, M. Kawano, M. Ando, A. Ogawa, K.
Sadakane, H. Iwase, H. Shirota
Anion effects on the mixing states of 1-methyl-3-octylimidazolium
tetrafluoroborate and bis(trifluoromethylsulfonyl)amide with methanol, acetonitrile, and dimethyl sulfoxide on the meso- and microscopic scales
J. Phys. Chem. B, 125 13896-13907 (2021).

91

M. H. Petersen, N. Vernet, W. P. Gates, F. J. Villacorta, S. OhiraKawamura, Y. Kawakita, M. Arai, G. Kneller, H. N. Bordallo
Assessing diffusion relaxation of interlayer water in clay minerals using a minimalist three-parameter model
J. Phys. Chem. C, 125 15085 (2021).

92

K. Ito, T. Yamada, A. Shinohara, S. Takata, Y. Kawakita
Dynamics of water in a catalyst layer of a fuel cell by quasielastic
neutron scattering
J. Phys. Chem. C, 125 21645 (2021).

93

P. Luo, Y. Zhai, J. B. Leao, M. Kofu, K. Nakajima, A. Faraone, Y Z
Neutron Spin−Echo Studies of the Structural Relaxation of Network
Liquid ZnCl2 at the Structure Factor Primary Peak and Prepeak
J. Phys. Chem. Lett., 12 392-398 (2021).

94

N. Yamamoto, M. Kofu, K. Nakajima, H. Nakagawa, N. ShibayamaFreezable and Unfreezable Hydration Water: Distinct Contributions
to Protein Dynamics Revealed by Neutron Scattering
J. Phys. Chem. Lett., 12 2172 (2021).

95

L. J. Bannenberg, H. Schreuders, H. Kim, K. Sakaki, S. Hayashi, K.
Ikeda, T. Otomo, K. Asano, B. Dam
Suppression of the Phase Coexistence of the fcc–fct Transition in
Hafnium-Hydride Thin Films
J. Phys. Chem. Lett., 12 10969-10974 (2021).

96

X. Wang, X, Tang, P. Zhang, Y. Wang, D. Gao, J. Liu, K. Hui, Y. Wang,
Y. Wang, X. Dong, T. Hattori, A. Sano-Furukawa, K. Ikeda, P. Miao, X.
Lin, M. Tang, Z. Zuo, H. Zheng, K. Li, H-k. Ma
Crystalline Fully Carboxylated Polyacetylene Obtained under HighMLF Annual Report 2021

Pressure as a Li-Ion Battery Anode Material
J. Phys. Chem. Lett., 12 12055-12061 (2021).
97

M. Tabuchi, Y. Kobayashi
Appearance of pentavalent Fe ion as a result of a charge disproportionation in Fe-substituted Li2MnO3J. Phys. Chem. Solids, 150 109862 (2021).

98

K. Itoh, R. Yamada, J. Saida, K. Ikeda, T. Otomo
Atomic-level characterization of free volume in the structure of
Cu67Zr33 amorphous alloy
J. Phys. Condens. Matter., 33 274001 (2021).

99

H. K. Yoshida, H. Okabe, S. Takeshita, H. Luetkens, A. Koda, R.
KadonoμSR Study of Kapellasite-type Quantum Kagome Antiferromagnet
CaCu3(OH)6Cl2 ∙ 0.6H2O
J. Physical Soc. Japan, 91 013701 (2021).

100 S. Hosokawa, Y. Kawakita, L. Pusztai, K. Ikeda, T. Otomo
Detailed investigations on short- and intermediate-range structuresof Ge-Se glasses near the stiffness transition composition
J. Physical Soc. Japan, 90 024601 (2021).
101 M. Fujita, K. Ikeuchi, R. Kajimoto, M. Nakamura
Magnetic Excitations of Sr 3Ir2O7 Observed by Inelastic Neutron
Scattering Technique
J. Physical Soc. Japan, 90 025001 (2021).
102 K. Kaneko, T. Kawasaki, A. Nakamura, K. Munakata, A. Nakao, T.
Hanashima, R. Kiyanagi, T. Ohhara, M. Hedo, T. Nakama, Y. Ōnuki
Charge-Density-Wave Order and Multiple Magnetic Transitions in
Divalent Europium Compound EuAl4
J. Physical Soc. Japan, 90 064704 (2021).
103 Y. Hwang, K. H. Lee, J.-H. Chung, K. Ikeuchi, V. O. Garlea, H.
Yamauchi, M. Akatsu, S. Shamoto
Spin Wave Excitations in Honeycomb Antiferromagnet MnTiO3
J. Physical Soc. Japan, 90 064708 (2021).
104 D. Ueta, M. Yoshida, T. Kobuke, Y. Ikeda, T. Masuda, H. Yoshizawa
Complex Magnetic Phase Diagram in the Non-CentrosymmetricCompound CePtSi3
J. Physical Soc. Japan, 90 064712 (2021).
105 K. Matsubayashi, H. Okamura, T. Mizokawa, N. Katayama, A.
Nakano, H. Sawa, T. Kaneko, T. Toriyama, T. Konishi, Y. Ohta, H.
Arima, R. Yamanaka, A. Hisada, T. Okada, Y. Ikemoto, T. Moriwaki,
K. Munakata, A. Nakao, M. Nohara, Y. Lu, H. Takagi, Y. Uwatoko
Hybridization-Gap Formation and Superconductivity in the PressureInduced Semimetallic Phase of the Excitonic Insulator Ta2NiSe5
J. Physical Soc. Japan, 90 074706 (2021).
106 K. Kodama, T. Honda, H. Yamauchi, S. Shamoto, K. Ikeda, T. Otomo
Magnetic structure of short-range ordering in intermetallic antiferromagnet Mn3RhSi
J. Physical Soc. Japan, 90 074710 (2021).
107 Y. Nambu, S. Shamoto
Neutron Scattering Study on Yttrium Iron Garnet for Spintronics
J. Physical Soc. Japan, 90 081002 (2021).
108 S. Shamoto, H. Yamauchi, K. Ikeuchi, M. K. Lee, L.-J. Chang, V. O.
Garlea, I. Y. Hwang, K. H. Lee, J.-H. Chung
Spin-flop Phase in a Honeycomb Antiferromagnet Mn0.84Mg0.16TiO3
J. Physical Soc. Japan, 90 093703 (2021).
109 D. Ueta, T. Kobuke, H. Shibata, M. Yoshida, Y. Ikeda, S. Itoh, T. Yokoo,
T. Masuda, H. Yoshizawa
Crystalline electric field level scheme in the non-centrosymmetric
CeRhSi3 and CeIrSi3
J. Physical Soc. Japan, 90 104706 (2021).

MLF Operations in 2021

110 M. Fujita, T. Taniguchi, T. Wang, S. Torii, T. Kamiyama, K. Ohashi, T.
Kawamata, T. Takamatsu, T. Adachi, M. Kato, Y. Koike
Reduction Annealing Effects on the Crystal Structure of T'-type
La1.8Eu0.2CuO4+α−δJ. Physical Soc. Japan, 90 105002 (2021).
111 D. Ueta, M. Yoshida, T. Kobuke, Y. Ikeda, A. Nakao, T. Moyoshi, K.
Munakata, Y. Liu, T. Masuda, H. Yoshizawa
Oval-cycloidal Magnetic Structure with Phase-shift in the Noncentrosymmetric Tetragonal Compound CePdSi3
J. Physical Soc. Japan, 90 114702 (2021).
112 K. Nawa, Y. Imai, Y. Yamaji, H. Fujihara, W. Yamada, R. Takahashi, T.
Hiraoka, M. Hagihala, S. Torii, T. Aoyama, T. Ohashi, Y. Shimizu, H.
Gotou, M. Itoh, K. Ohgushi, T. J. Sato
Strongly Electron-Correlated Semimetal RuI3 with a Layered
Honeycomb Structure
J. Physical Soc. Japan, 90 123703 (2021).
113 K. Iwasa, S. Nakazato, D. Hashimoto, M. Shiozawa, K. Kuwahara,
H. Sagayama, S. Ohira-Kawamura, N. Murai, D. T. Adroja. A. M.
Strydom
Magnetic excitations in chiral-structure phase of Ce3Ir4Sn13
J. Physical Soc. Japan, 90 124701 (2021).
114 Y. Idemoto, M. Ichiyama, N. Ishida, N. Kitamura
Structural and electronic properties of spinel type Mg1+yCo2-x-yMnxO4
for cathode applications in magnesium rechargeable batteries
J. Power Sources, 482 228920 (2021).
115 H. Yamada, N. Morimoto, H. Mukohara, T. Tojo, S. Yano, E. Magome,
T. Morimura, R. Bekarevich, K. Mitsuishi
Concerted influence of microstructure and adsorbed water on lithium-ion conduction of Li1.3Al0.3Ti1.7(PO4)3
J. Power Sources, 511 230422 (2021).
116 N. Ishida, K. Kawagoe, N. Kitamura, J. Akimoto, Y. Idemoto
Average and local structure analysis of Na/Li ion-exchanged
Lix(Mn,Ni,Ti)O2 using synchrotron X-ray and neutron sources
J. Solid State Chem., 25 1319-1326 (2021).
117 J. Hendriks, N. O'Dell, A. Wills, A. Tremsin, C. Wensrich, T. Shinohara
Bayesian non-parametric Bragg-edge fitting for neutron transmission strain imaging
J. Strain Anal. Eng. Des., 56 371-385 (2021).
118 K. Hirota, T. Ariga, M. Hino, G. Ichikawa, S. Kawasaki, M. Kitaguchi,
K. Mishima, N. Muto, N. Naganawa, H. M. Shimizu
Neutron Imaging Using a Fine-Grained Nuclear Emulsion
J. Imaging, 7 4 (2021).
119 K. Isegawa, D. Setoyama, H. Kimura, T. Shinohara
The First Application of a Gd3Al2Ga3O12:Ce Single-Crystal Scintillator
to Neutron Radiography
J. Imaging, 7 232 (2021).
120 S. Sasada, K. Hiroi, K. Osanai, T. Shinohara, K. Watanabe, A. Uritani
High-spatial-resolution measurement of magnetization distribution
using polarized neutron imaging
Jpn. J. Appl. Phys., 60 126003 (2021).
121 M. Yotsuzuka, T. Iijima, H. Iinuma, K. Inami, M. Otani, N. Kawamura,
R. Kitamura, Y. Kondo, N. Saito, K. Shimomura, Y. Sue, Y. Nakazawa,
K. Hasegawa, K. Futatsukawa, T. Mibe, Y. Miyake, T. Morishita, H.
Yasuda, T. Yamazaki
Simulation of the Beam Commissioning Method for a Muon APF IHDTL in the J-PARC Muon g – 2/EDM Experiment
JPS Conf. Proc., 33 011040 (2021).
122 N. Kawamura on behalf of muon science section MLF J-PARC
Current Status of Muon Science Facility
JPS Conf. Proc., 33 011052 (2021).

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MLF Operations in 2021

MLF Annual Report 2021

123 M. Ohta, A. Koda, C. Ohmori, Y. Yoshizawa, K. Ogura, Y. Miyake
Magnetic Field Dependence on Crystallization Process of FINEMET®
Nano-crystalline Alloy Detected by μSR Method
JPS Conf. Proc., 33 011053 (2021).
124 Y. Shoda, T. Igarashi, H. Yamashita, Y. Kitamura, S. Takata, K. Ohishi,
D. Aoki, K. Tsunoda, H. Otsuka
Structural analysis of polybutadienes with urethane linkages bysmall-angle neutron scattering
JPS Conf. Proc., 33 011054 (2021).
125 Y. Ishikawa, R. Kiyanagi, Y. Noda
Electrostatic Potential Mapping by Maximum Entropy Method basedon Mott-Bethe relations
JPS Conf. Proc., 33 011055 (2021).
126 N. Sumi, K. Hirota, G. Ichikawa, T. Ino, Y. Iwashita, S. Kajiwara, Y.
Kato, M. Kitaguchi, K. Mishima, K. Morikawa, T. Mogi, H. Oide, H.
Okabe, H. Otono, T. Shima, H. M. Shimizu, Y. Sugisawa, T. Tanabe, S.
Yamashita, K. Yano, T. Yoshioka
Precise Neutron Lifetime Measurement Using Pulsed Neutron Beams
at J-PARCJPS Conf. Proc., 33 011056 (2021).
127 M. Takahashi, R. Miyazaki, T. Kawasaki, S. Harjo
Phase Transitions and Atomic Ordering in Cu–Pd–Fe Ternary Alloys
JPS Conf. Proc, 33 011057 (2021).
128 S. Itoh, T. Masuda, T. Yokoo, H. Yoshizawa, M. Soda, S. Asai, Y. Ikeda,
S. Ibuka, M. Yoshida, T. Hawai, H. Saito, D. Kawana, R. Sugiura, T.
Asami, Y. Ihata
Dynamical studies in condensed matter on High Resolution Chopper
Spectrometer (HRC) – 2nd phase of HRC project –JPS Conf. Proc., 33 011058 (2021).
129 K. Kodama, T. Honda, K. Ikeda, S. Shamoto, T. Otomo
Magnetic Pair Distribution Function of Spin-glass System
Mn0.5Fe0.5TiO3
JPS Conf. Proc., 33 011059 (2021).
130 K. Ohishi, Y. Kousaka, S. Iwasaki, J. Akimitsu, M. Pardo-Sainz, V.
Laliena, J. Campo, M. Ohkuma, M. Mito
Small angle neutron scattering study near the critical field at low
temperature in MnSi
JPS Conf. Proc., 33 011060 (2021).
131 K. Maruyama, S. Tanaka, R. Kiyanagi, A. Nakao, K. Moriyama, Y.
Ishikawa, S. Utsumi
Helimagnetism of Ba(Fe 1−xSc x) 12O 19 Studied by Magnetization
Measurement and Neutron Diffraction
JPS Conf. Proc., 33 011061 (2021).
132 K. Oikawa, S. Harjo, A. H. Pham, T. Kawasaki, S. Morito, Y. Kiyanagi,
T. Shinohara, T. Kai, T. Ohba, M. Ito
Microstructure Distribution of Japanese Sword Cross Sections
Analyzed by the Diffractometer TAKUMI at J-PARC
JPS Conf. Proc, 33 011062 (2021).
133 T. Yamashita, S. Harjo, O. Umezawa, T. Kawasaki
Neutron Diffraction Mapping Measurement for Japanese Nails in theAncient and Present Days
JPS Conf. Proc, 33 011063 (2021).
134 T. Yamashita, S. Tomono, S. Morooka, S. Harjo, T. Kawasaki, T.
Nameki, N. Koga, O. Umezawa
Stress Partitioning Behavior of Duplex Alloys Consisting of BCC and
FCC Phases at Low Temperature
JPS Conf. Proc, 33 011064 (2021).
135 D. Setoyama, H. Kimura, T. Shinohara, Y. Matsumoto
Non-Destructive 3D Neutron Imaging for Power Electronic Module
JPS Conf. Proc., 33 011065 (2021).

192

136 A. Nakao, T. Moyoshi, K. Moriyama, T. Matsumura, K. Iba, S. Ohara,
Y. Ishikawa, K. Munakata, T. Ohhara, R. Kiyanagi
Determination of Crystallographic Planes for a Polyhedral Single
CrystalJPS Conf. Proc., 33 011067 (2021).
137 M. Matsuura, T. Yamada, T. Tominaga, M. Kobayashi, H. Nakagawa,Y. Kawakita
Position Dependency of the Scattered Intensity in the Time-of-flight
Backscattering Spectrometer DNA
JPS Conf. Proc., 33 011068 (2021).
138 S. Hosokawa, J. R. Stellhorn, Y. Onodera, S. Kohara, H. Tajiri, E.
Magome, L. Pusztai, K. Ikeda, T. Otomo, M. Krbal, T. Wagner
Local- and Intermediate-Range Atomic Order in Ga2Ge3Se9 Glass:Complementary Use of X-Rays and Neutrons
JPS Conf. Proc., 33 011069 (2021).
139 S. Hosokawa, Y. Kawakita, J. R. Stellhorn, L. Pusztai, N. Blanc, N.
Boudet, K. Ikeda, T. Otomo
Local- and Intermediate-Range Order in Room Temperature
Superionic Conducting Ag-GeSe3 Glasses
JPS Conf. Proc., 33 011070 (2021).
140 Y. Kawakita, T. Kikuchi, S. Tahara, M. Nakamura, Y. Inamura, K.
Maruyama, Y. Yamauchi, S. Ohira-Kawamura, K. Nakajima
Mode distribution analysis for superionic melt of CuI by coherent
quasielastic neutron scattering
JPS Conf. Proc., 33 011071 (2021).
141 K. Ninomiya, T. Kudo, A. Shinohara, M. Tampo, S. Takeshita, Y.
Miyake, M. K. Kubo
Muonic X-ray Identification of Nuclear Materials Sealed in a Box
JPS Conf. Proc., 33 011072 (2021).
142 Y. Miyazaki, S. Watanabe, M. Nakamura, A. Shibata, K. Nomura, T.
Kai, J. D. Parker
Observation of Eu Adsorption Band in the CMPO/SiO2–P Column by
Neutron Resonance Absorption Imaging
JPS Conf. Proc., 33 011073 (2021).
143 Y. Tsuchikawa, Y. Abe, Y. Ohishi, T. Kai, Y. Toh, M. Segawa, M. Maeda,
A. Kimura, S. Nakamura, M. Harada, K. Oikawa, Y. Matsumoto, J. D.
Parker, T. Shinohara, Y. Nagae, I. Sato
Feasibility study of PGAA for boride identification in simulated melted core materials
JPS Conf. Proc., 33 011074 (2021).
144 Y. Abe, Y. Tsuchikawa, T. Kai, Y. Matsumoto, J. D. Parker, T. Shinohara,
Y. Ohishi, T. Kamiyama, Y. Nagae, I. Sato
Visualization of the Boron Distribution in Core Material Melting and
Relocation Specimen by Neutron Energy Resolving Method
JPS Conf. Proc., 33 011075 (2021).
145 F. Kaneko, A. Radulescu, H. Iwase, S. Takata, M. Nishiura, Z. Hou
Application of simultaneous measurement system combining wide
q-range small-angle neutron scattering and polarized Fourier transform infrared spectroscopy: Cocrystal of syndiotactic polystyrene
with methyl benzoate
JPS Conf. Proc., 33 011076 (2021).
146 F. Nemoto, N. L. Yamada, F. Takabatake, H. Seto
Installation of a Rheometer on Neutron Reflectometer SOFIA
at J-PARC toward Rheo-NR and Observation for Crystallization
Behavior of Cocoa Butter in Chocolate
JPS Conf. Proc., 33 011077 (2021).
147 H. Iwase, R. Kawai, T. Yoshimura, S. Takata
Rheo-SANS study on shear thinning behavior of cationic gemini surfactant (12–2–12) in salt-free solution
JPS Conf. Proc., 33 011078 (2021).

MLF Annual Report 2021

148 J. Kobayashi, Y. Kasama, W. Fujii, E. Tominaga, H. Iwase, H. Nanbu
Structural analysis of microemulsion formed from polymer surfactant polyglycerol esters in the manufacturing process
JPS Conf. Proc., 33 011079 (2021).
149 M. Nakada, T. Yamada, K. Ikeda, T. Otomo
Static and Dynamic Structure Analysis of Intermediate Water on
Polyvinyl Pyrrolidone Using Neutron Scattering
JPS Conf. Proc., 33 011080 (2021).
150 M. Iguchi, Y. Fujii, K. Hori, F. Nemoto, N. Torikai
Thermal Stability and Interfacial Segregation for Polymer Thin Films
Blended with a Homologue Having Different Tacticity
JPS Conf. Proc., 33 011081 (2021).
151 T. Honda, G. Nishikawa, Y. Fujii, S. Inada, H. Iwase, N. Torikai
Adsorbed polymer effects on particle dispersion in polymeric matrix
examined by SANSJPS Conf. Proc., 33 011082 (2021).
152 T. Tominaga, T. Yamada
Water dynamics of double-network polymers in a primally hierarchical structure
JPS Conf. Proc., 33 011083 (2021).
153 T. Yamada, H. Arima, T. HattoriCommissioning for QENS Experiments at Pressures Up to 200 MPa at
MLF, J-PARC
JPS Conf. Proc., 33 011084 (2021).
154 T. Yamada, T. Tominaga
In Situ Quasi-Elastic Neutron Scattering of Nafion Membrane with
Water–Vapor Pressure Control System
JPS Conf. Proc., 33 011085 (2021).
155 T. Tominaga, Y. Kawakita, H. Nakagawa, T. Yamada, K. Shibata
Quartz Cell for a Backscattering Spectrometer
JPS Conf. Proc., 33 011086 (2021).
156 F. Funama, M. Hino, T. Oda, H. Endo, T. Hosobata, Y. Yamagata, S.
Tasaki, Y. Kawabata
A study of Focusing TOF-MIEZE Spectrometer with Small-angle
Neutron Scattering
JPS Conf. Proc., 33 011088 (2021).
157 K. Nakajima, S. Ohira-Kawamura, M. Kofu, N. Murai, Y. Inamura, T.
Kikuchi, D. Wakai
Recent update of AMATERAS: a cold-neutron disk-chopper
spectrometer
JPS Conf. Proc., 33 011089 (2021).
158 S. Imajo, Y. Iwashita, K. Mishima, M. Kitaguchi, H. M. Shimizu, T. Ino,
S. Yamashita, K. Hirota, F. Goto, Y. Fuwa, R. Katayama
Ultracold Neutron Time Focusing Experiment and Performance
Evaluation of an Improved UCN Rebuncher at J-PARC/MLF
JPS Conf. Proc., 33 011091 (2021).
159 R. Maruyama, D. Yamazaki, K. Akutsu-Suyama, T. Hanashima, N.
Miyata, H. Aoki, K. Soyama
Improvement in sputtering rate uniformity over large depositionarea of large-scale ion beam sputtering system
JPS Conf. Proc., 33 011092 (2021).
160 T. Tominaga, M. Sahara, Y. Kawakita, H. Nakagawa, N. Shimamoto
Corrosion of Aluminum-based Containers for Neutron Studies with
Aqueous Samples under Low Temperatures
JPS Conf. Proc., 33 011094 (2021).
161 T. Tominaga, M. Kobayashi, T. Yamada, M. Matsuura, Y. Kawakita, S.
Kasai
Position-Encoded Automatic Cell Elevator for BL02, J-PARC MLF
JPS Conf. Proc., 33 011095 (2021).

MLF Operations in 2021

162 T. Okudaira, T. Oku, K. Sakai, K. Hiroi, T. Shinohara, T. Ino, H. Kira, H.
Hayashida, J. Suzuki, K. Kakurai, K. Aizawa
A Neutron Depolarization Measurement of Single Crystal Fe by Usinga 3He Neutron Spin Filter and Magnetic Super-mirrors
JPS Conf. Proc., 33 011096 (2021).
163 T. Nakamura, T. Kawasaki, K. Toh, S. Harjo, K. Sakasai, K. Aizawa
A Two-Dimensional Scintillation Neutron Detector for TAKUMI
Diffractometer in J-PARC MLF
JPS Conf. Proc, 33 011097 (2021).
164 Y. Sakaguchi, S. Kasai, K. Ohuchi, T. Morikawa, H. Iwase, M.
Akamatsu, H. Sakai, A.-A. A. Simon, M. Mitkova, R. Takahashi
Recent development of the sample environment for light irradiation
experiments at the Materials and Life Science Experimental Facility
JPS Conf. Proc., 33 011100 (2021).
165 H. Nakagawa, Y. Yonetani, K. Nakajima, S. Ohira-Kawamura, T.
Kikuchi, Y. Inamura, M. Kataoka, H. Kono
Sequence-dependent hydration water dynamics of dodecamericDNA
JPS Conf. Proc, 33 011101 (2021).
166 T. Yoshioka, T. Aoyagi, Y. Fujita, Y. Honda, H. Ikeda, M. Ikeno,
K. Kawagoe, T. Kishishita, T. Kohriki, T. Kume, S. Kurumida, M.
Matama, T. Mibe, T. Murakami, K. Namba, S. Nishimura, N. Saito,
O. Sasaki, T. Sata, N. Sato, Y. Sato, H. Sendai, S. Shirabe, M. Shoji, T.
Suda, Y. Sue, T. Suehara, M. Tanaka, T. Takatomi, J. Tojo, K. Tsukada,
Y. Tsusumi, T. Uchida, K. Ueno, T. Ushizawa, T. Yamanaka, H. Yasuda,
and J-PARC muon g − 2/EDM Collaboration
Positron Tracking Detector for Muon g – 2/EDM Experiment at
J-PARCJPS Conf. Proc., 33 011108 (2021).
167 K. Sakai, T. Oku, T. Okudaira, T. Kai, M. Harada, K. Hiroi, H. Hayashida,
K. Kakurai, H. M. Simizu, K. Hirota, T. Yamamoto, T. Ino
Study of neutron–nuclear spin correlation term with a polarized XetargetJPS Conf. Proc., 33 011116 (2021).
168 K. Yano, Y. Makida, S. Makise, K. Mishima, H. Otono, N. Sumi, T.
YoshiokaPrecise Neutron Lifetime Measurement: An Integration Test with a
Gaseous and a Solenoidal Magnet
JPS Conf. Proc., 33 011117 (2021).
169 M. Hiromoto, T. Hori, R. Kondo, S. Hara, T. Shima, R. Nakabe, N. OI,
H. M. Shimizu, K. Hirota, M. Kitaguchi, C. C. Haddock, W. M. Snow,
T. Yoshioka, K. Mishima, T. Ino
Proof-of-principle Experiment for the Study of a New Intermediaterange Interaction Using Coherent Neutron Scattering
JPS Conf. Proc., 33 011118 (2021).
170 N. Yamamoto, M. Kitaguchi, H. M Shimizu, Y. Seki, K. Mishima
Development of Pulsed Neutron Interferometer
JPS Conf. Proc., 33 011119 (2021).
171 N. Kawamura, R. Kitamura, H. Yasuda, M. Otani, Y. Nakazawa, H.
Iinuma, T. Mibe
A New Approach for Mu − Mu Conversion Search
JPS Conf. Proc., 33 011120 (2021).
172 C. Zhang, H. Hara, T. Hiraki, Y. Ikedo, Y. Imai, K. Ishida, S. Kamal,
N. Kawamura, A. Koda, Y. Mao, T. Masuda, T. Mibe, Y. Miyake, Y.
Miyamoto, Y. Oishi, M. Otani, P. Strasser, K. Shimomura, K. Suzuki,
S. Uetake, T. Yamazaki, S. Yamamoto, K. Yoshimura, M. Yoshida
Simulation Study of Laser Ionization of Muonium by 1S-2S Excitation
for the Muon g – 2/EDM Experiment at J-PARC
JPS Conf. Proc., 33 011125 (2021).
173 H. Yasuda, H. Iinuma, N. Kawamura, R. Kitamura, Y. Kondo, T. Mibe,
Y. Nakazawa, M. Otani, N. Saito, Y. Sue, Y. Takeuchi, T. Yamazaki, M.

193

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MLF Annual Report 2021

Yotsuzuka
Development of Spin Flip Analysis for the J-PARC Muon g – 2/EDM
Experiment
JPS Conf. Proc., 33 011126 (2021).
174 Y. Nakazawa, H. Iinuma, Y. Iwashita, Y. Iwata, E. Cicek, M. Otani,
N. Kawamura, R. Kitamura, Y. Kondo, N. Saito, Y. Sue, Y. Takeuchi,
K. Hasegawa, N. Hayashizaki, T. Mibe, T. Morishita, H. Yasuda, T.
Yamazaki, M. Yoshida, M. Yotsuzuka
Multipacting Simulations of Coaxial Coupler for IH-DTL Prototype in
Muon Accelerator
JPS Conf. Proc., 33 011128 (2021).
175 Y. Takeuchi, K. Futatsukawa, K. Hasegawa, N. Hayashizaki, H.
Iinuma, T. Ito, Y. Iwashita, Y. Iwata, N. Kawamura, R. Kitamura, Y.
Kondo, T. Mibe, T. Morishita, F. Naito, Y. Nakazawa, M. Otani, T.
Yamazaki, N. Saito, Y. Sue, H. Yasuda, M. Yoshida
Error Studies for Muon Linac in the Muon g – 2/EDM Experiment at
J-PARCJPS Conf. Proc., 33 011129 (2021).
176 N. Kawamura, S. Makimura, A. Koda, S. Matoba, Y. Kobayashi
Safety Measure Against Tritium in the MLF Muon Target
JPS Conf. Proc., 33 011146 (2021).
177 K. Sakai, M. Ooi, K. Haga, T. Kai, T. Nakatani, Y. Kobayashi, A.
WatanabeUpgrade History and Present Status of the General Control System
for the Materials and Life Science Experimental Facility at J-PARC
JPS Conf. Proc., 33 011151 (2021).
178 H. Aoki, H. Ogawa, M. Takenaka
Neutron reflectometry tomography for imaging and depth structure
analysis of thin films with in-plane inhomogeneity
Langmuir, 37 196-203 (2021).
179 H. Iwase, M. Kubota, T. Itoh, T. Ogura, T. Ebina, H. Ohtani, K.
Kurosaka, Y. Fukushima
Direct observation of the relationship between thixotropic behavior
and shear-induced orientation of clay particles in synesthetic hectorite suspensions
Langmuir, 37 6435–6441 (2021).
180 T. Miyazaki, N. Miyata, H. Arima-Osonoi, H. Kira, K. Ohuchi, S. Kasai,
Y. Tsumura, H. Aoki
Layered Structure in the Crystalline Adsorption Layer and theLeaching Process of Poly(vinyl alcohol) Revealed by Neutron
Reflectivity
Langmuir, 37 9873-9882 (2021).
181 M. Akamatsu, K. Saito, H. Iwase, T. Ogura, K. Sakai, H. Sakai
Contrast variation small-angle neutron scattering study of solubilization of perfumes in cationic surfactant micelles
Langmuir, 37 10770–10775 (2021).
182 M. Harada, M. Yamamoto, H. Iwase
Combined small-angle neutron scattering/small-angle X‑ray scattering analysis for the characterization of silver nanoparticles prepared via photoreduction in water-in-oil microemulsions
Langmuir, 37 13085 (2021).
183 A. Izumi, Y. Shudo, M. Shibayama, N. Miyata, T. Miyazaki, H. Aoki
In Situ Neutron Reflectometry Analysis of Interfacial Structure
Formation between Phenolic Resin and Silica during Curing
Langmuir, 37 13867-13872 (2021).
184 K. Shimokita, K. Yamamoto, N. Miyata, Y. Nakanishi, H. Ogawa, M.
Takenaka, N. L. Yamada, T. Miyazaki
Investigation of Interfacial Water Accumulation between
Polypropylene Thin Film and Si Substrate by Neutron Reflectivity
Langmuir, 37 14550–14557 (2021).

194

185 H. Taneda, N. L. Yamada, F. Nemoto, Y. Minagawa, H. Matsuno, K.
TanakaModification of a Polymer Surface by Partial Swelling Using
Non-solvents
Langmuir, 37 14941–14949 (2021).
186 H. Ogawa, M. Takenaka, T. Miyazaki
Molecular Weight Effect on the Transition Processes of a SymmetricPS-b-P2VP during Spin-Coating
Macromolecules, 54 1017 (2021).
187 Y. Kimura, S. Imai, M. Takenaka, T. Terashima
Amphiphilic random cyclocopolymers as versatile scaffolds for ringfunctionalized and self-assembled materials
Macromolecules, 54 3987 (2021).
188 K. Aizawa, W. Gong, S. Harjo, T. Kawasaki
Kink Deformation Dynamics of LPSO Alloy from the Experimental
Viewpoint of Multilayer Structure Deformation
Magnesium 2021, 247-254 (2021).
189 X. X. Zhang, H. Andrä, S. Harjo, W. Gong, T. Kawasaki, A. Lutz, M.
LahresQuantifying internal strains, stresses, and dislocation density in additively manufactured AlSi10Mg during loading-unloading-reloading
deformation
Mater. Des., 198 109339 (2021).
190 H. Saitoh, T. Sato, M. Tanikami, K. Ikeda, A. Machida, T. Watanuki, T.
Taguchi, S. Yamamoto, T. Yamaki, S. Takagi, T. Otomo, S. Orimo
Hydrogen storage by earth-abundant metals, synthesis and characterization of Al3FeH3.9
Mater. Des., 109953 (2021).
191 S. Shamoto, M. K. Lee, Y. Fujimura, K. Kondo, T. U. Ito, K. Ikeuchi, S.
Yasuda, L.-J. Chang
Gallium-effect in a lead-free solder for silver-sheathed superconducting tape
Mater. Res. Express, 8 076303 (2021).
192 T. Yamashita, N. Koga, T. Kawasaki, S. Morooka, S. Tomono, O.
Umezawa, S. Harjo
Work hardening behavior of dual phase copper–iron alloy at low
temperature
Mater. Sci. Eng. A Struct. Mater., 819 141509 (2021).
193 M. Kumagai, K. Akita, M. Kuroda, S. Harjo
In situ diffraction characterization on microstructure evolution in
austenitic stainless steel during cyclic plastic deformation and its
relation to the mechanical response
Mater. Sci. Eng. A Struct. Mater., 820 141582 (2021).
194 Y. S. Kim, H. Chae, W. Woo, D. K. Kim, D. H. Lee, S. Harjo, T. Kawasaki,
S. Y. Lee
Multiple deformation scheme in direct energy deposited CoCrNi medium entropy alloy at 210K
Mater. Sci. Eng. A Struct. Mater., 828 142059 (2021).
195 W. Mao, W. Gong, T. Kawasaki, S. Harjo
Effect of deformation-induced martensitic transformation on nonuniform deformation of metastable austenitic steel
Mater. Sci. Eng. A Struct. Mater., 837 142758 (2021).
196 Y. S. Kim, H. Chae, E.-W. Huang, J. Jain, S. Harjo, T. Kawasaki, S. I.
Hong, S. Y. Lee
Microstructural Evolution and Mechanical Properties of NonEquiatomic (CoNi)74.66Cr17Fe8C0.34 High-Entropy Alloy
Materials, 15 1312 (2021).
197 Y. Onuki, T. Hirano, K. Umemura, S. Sato, T. Tomida
In Situ Neutron Diffraction Measurement during Bainite
Transformation and Accompanying Carbon Enrichment in Austenite

MLF Annual Report 2021

at iMATERIA, J-PARC MLF
Materials Science Forum, 1016 1079 (2021).
198 T. Naoe, H. Kinoshita, H. Kogawa, T. Wakui, E. Wakai, K. Haga, H.
TakadaEffect of Gas Microbubble Injection and Narrow Channel Structure
on Cavitation Damage in Mercury Target Vessel
Materials Science Forum, 1024 111 (2021).
199 T. Wakui, E. Wakai, H. Kogawa, T. Naoe, K. Hanano, K. Haga, T.
Shimada, K. Kanomata
New Design of High Power Mercury Target Vessel of J-PARC
Materials Science Forum, 1024 145 (2021).
200 S. Nishida, S. Nishino, M. Sekine, Y. Oka, S. Harjo, T. Kawasaki, H.
Suzuki, Y. Morii, Y. Ishii
Analysis of Residual Stress in Steel Bar Processed by Cold Drawing
and Straightening
Mater. Trans., 62 667-674 (2021).
201 T. Nakagawa, D. Heshiki, H. Higa, J. Kawakami, R. Kobayashi, N.
Hanada, K. Ikeda, T. Otomo, H. Ofuchi, M. Ishida
Structural properties of (Ti, Zr)(Mn,Cr)2M0.1 (M=none, Fe, Co, Ni, andCu) hydrogen storage alloys: Composition distribution and occupied
site of doped element
Mater. Trans., 62 899 (2021).
202 N. Koga, O. Umezawa, M. Yamamoto, T. Yamamoto, T. Yamashita, S.
Morooka, T. Kawasaki, S. Harjo
Effect of Solute Carbon on the Characteristic Hardening of Steel atHigh Temperature
Metall. Mater. Trans. A Phys. Metall. Mater. Sci., 52 897-901 (2021).
203 N. Tsuchida, S. Harjo
Enhancement of Uniform Elongation by Temperature Change during Tensile Deformation in a 0.2C TRIP Steel
Metals, 11 2053 (2021).
204 K. J. Gi, B. J. Wung, P. J. Min, W. Wanchuck, H. Stefanus, L. Sunghak,
K. H. Seop
Effect of the Difference in Strength of Hard and Soft Components on
the Synergetic Strengthening of Layered Materials
Metals and Materials International, 27 376-383 (2021).
205 L. Temleitner, T. Hattori, J. Abe, Y. Nakajima, L. Pusztai
Pressure Dependent Structure of Methanol-Water Mixtures up 1.2
GPa: Neutron Diffraction Experiments and Molecular Dynamics
Simulations
Molecules, 26 1218 (2021).
206 H. He, M. Naeem, F. Zhang, Y. Zhao, S. Harjo, T. Kawasaki, B. Wang,
X. Wu, S. Lan, Z. Wu, W. Yin, Y. Wu, Z. Lu, J-J. Kai, C-T. Liu, X-L. Wang
Stacking Fault Driven Phase Transformation in CrCoNi Medium
Entropy Alloy
Nano Lett., 21 1419-1426 (2021).
207 S. Gao, T. Broux, S. Fujii, C. Tassel, K. Yamamoto, Y. Xiao, I. Oikawa,
H. Takamura, H. Ubukata, Y. Watanabe, K. Fujii, M. Yashima, A.
Kuwabara, Y. Uchimoto, H. Kageyama
Hydride-based antiperovskites with soft anionic sublattices as fastalkali ionic conductors
Nat. Commun., 12 201 (2021).
208 R. Yamane, K. Komatsu, J. Gouchi, Y. Uwatoko, S. Machida, T.
Hattori, H. Ito, H. Kagi
Experimental evidence for the existence of a second partially-ordered phase of ice VI
Nat. Commun., 12 1129 (2021).
209 P. Park, K. Park, J. Oh, K. H. Lee, J. C. Leiner, H. Sim, T. Kim, J. Jeong,
K. C. Rule, K. Kamazawa, K. Iida, T. G. Perring, H. Woo, S.-W. Cheong,
M. E. Zhitomirsky, A. L. Chernyshev, J.-G. ParkMLF Operations in 2021

Spin texture induced by non-magnetic doping and spin dynamics in
2D triangular lattice antiferromagnet h-Y(Mn,Al)O3
Nat. Commun., 12 2306 (2021).
210 S.-Q. Su, S.-Q. Wu, M. Hagihala, P. Miao, Z. Tan, S. Torii, T. Kamiyama,
T. Xiao, Z. Wang, Z. Ouyang, Y. Miyazaki, M. Nakano, T. Nakanishi,
J.-Q. Li, S. Kanegawa, O. Sato
Water-oriented magnetic anisotropy transition
Nat. Commun., 12 2738 (2021).
211 R. Okuma, M. Kofu, S. Asai, M. Avdeev, A. Koda, H. Okabe, M.
Hiraishi, S. Takeshita, K. M. Kojima, R. Kadono, T. Masuda, K.
Nakajima, Z. Hiroi
Dimensional reduction by geometrical frustration in a cubic antiferromagnet composed of tetrahedral clusters
Nat. Commun., 12 4382 (2021).
212 G. Lin, J. Jeong, Y. Wang, Q. Huang, T. Masuda, S. Asai, S. Itoh, G.
Günther, M. Russina, Z. Lu, J. Sheng, L. Wang, C. Kim, J. Wang, G.
Wang, Q. Ren, C. Xi, W. Tong, L. Ling, Z. Liu, L. Wu, J. Mei, H. Zhou, Z.
Qu, J.-G. Park, Y. Wan, J. Ma
Field induced quantum spin disordered state in spin-1/2 honeycomb
magnet Na2Co2TeO6 with small Kitaev interaction
Nat. Commun., 12 5559 (2021).
213 P. Hua, M. Xia, Y. Onuki, Q. Sun
Nanocomposite NiTi shape memory alloy with high strength and fatigue resistanceNat. Nanotechnol., 16 409-413 (2021).
214 K. Yamanaka, M. Mori, K. Yoshida, Y. Onuki, S. Sato, A. Chiba
Surface evolution and corrosion behaviour of Cu-doped carbidereinforced martensitic steels in a sulfuric acid solution
npj Mater. Degrad., 5 43 (2021).
215 Y. Tsuchikawa, T. Kai, Y. Abe, Y. Ohishi, Y. Sun, K. Oikawa, T. Nakatani,
I. SatoMeasurement of Doppler broadening of prompt gamma-rays fromvarious zirconium- and ferro-borons
Nucl. Instrum. Methods Phys. Res. A, 991 164964 (2021).
216 B. Ma, M. Teshigawara, Y. Wakabayashi, M. Yan, T. Hashiguchi, Y.
Yamagata, S. Wang, Y. Ikeda, Y. Otake
Optimization of a slab geometry type cold neutron moderator for
RIKEN accelerator-driven compact neutron source
Nucl. Instrum. Methods Phys. Res. A, 995 165079 (2021).
217 N. Teshima, M. Aoki, Y. Higashino, H. Ikeuchi, K. Komukai, D. Nagao,
Y. Nakatsugawa, H. Natori, Y. Seiyaa, N. M. Truong, K. Yamamoto
Development of a multiwire proportional chamber with good tolerance to burst hits
Nucl. Instrum. Methods Phys. Res. A, 999 165228 (2021).
218 M. Harada, M. Teshigawara, M. Ooi, K. Oikawa, H. Takada, Y. Ikeda
Experimental characterization of high-energy component in extracted pulsed neutrons at the J-PARC spallation neutron source
Nucl. Instrum. Methods Phys. Res. A, 1000 165252 (2021).
219 D. Vu, H. Shishido, K. Aizawa, K. M. Kojima, T. Koyama, K. Oikawa,
M. Harada, T. Oku, K. Soyama, S. Miyajima, M. Hidaka, S. Y. Suzuki,
M. M. Tanaka A. Malins M. Machida, S. Kawamata, T. Ishida
Practical tests of neutron transmission imaging with a superconducting kinetic-inductance sensor
Nucl. Instrum. Methods Phys. Res. A, 1006 165411 (2021).
220 A. S. Tremsin, H. Z. Bilheux, J. C. Bilheux, T. Shinohara, K. Oikawa, Y.
GaoCalibration and optimization of Bragg edge analysis in energy-resolved neutron imaging experiments
Nucl. Instrum. Methods Phys. Res. A, 1009 165493 (2021).
221 F. Funama, S. Tasaki, M. Hino, T. Oda, H. Endo

195

MLF Operations in 2021

MLF Annual Report 2021

Double-focusing geometry for phase correction in neutron resonance spin-echo spectroscopy
Nucl. Instrum. Methods Phys. Res. A, 1010 165480 (2021).
222 A. D. Pant, K. Nagamine, E. Torikai, I. Shiraki, K. Shimomura, F. L.
Pratt, H. Ariga-Miwa, K. Ishida, J. S. Schultz
Muonium response to low oxygen levels in haemoglobin and otherbiological aqueous solutions and potential application towards
monitoring hypoxia
Nucl. Instrum. Methods Phys. Res. A, 1011 165561 (2021).
223 T. Oda, H. Endo, H. Ohshita, T. Seya, Y. Yasu, T. Nakajima, M. Hino, Y.
Kawabata
Phase correction method in a wide detector plane for MIEZE spectroscopy with pulsed neutron beams
Nucl. Instrum. Methods Phys. Res. A, 1012 165616 (2021).
224 S. Yamamoto, K. Ninomiya, N. Kawamura, T. Yabe, Y. Hirano
Three-dimensional (3D) optical imaging of muon beam using a plastic scintillator plate in water
Nucl. Instrum. Methods Phys. Res. A, 1015 165768 (2021).
225 D. Gao, X. Tang, X. Wang, X. Yang, P. Zhang, G. Chu, J. Han, T. Hattori,
Y. Wang, X. Dong, H. Zheng, K. Li, H-k. Mao
Phase transition and chemical reactivity of 1H-tetrazole under highpressure up to 100 GPa
Phys. Chem. Chem. Phys., 23 19503 (2021).
226 M. Kawano, K. Sadakane, H. Iwase, M. Matsugami, B. A. Marekha,
A. Idrissi, T. Takamuku
Assessment of the UCST-type liquid-liquid phase separation mechanism of imidazolium-based ionic liquid, [C8mim][TFSI], and 1,4-dioxane by SANS, NMR, IR, and MD simulations
Phys. Chem. Chem. Phys., 23 24449-24463 (2021).

233 Z. H. Zhu, J. Zhang, Z. F. Ding, C. Tan, C. S. Chen, Q. Wu, Y. X. Yang,
O. O. Bernal, P.-C. Ho, G. D. Morris, A. Koda, A. D. Hillier, S. P. Cottrell,
P. J. Baker, P. K. Biswas, J. Qian, X. Yao, D. E. MacLaughlin, L. Shu
Muon spin relaxation and fluctuating magnetism in the pseudogap
phase of YBa2Cu3Oy
Phys. Rev. B, 103 134426 (2021).
234 H. Okabe, M. Hiraishi, A. Koda, S. Takeshita, K. M. Kojima, I.
Yamauchi, T. Ohsawa, N. Ohashi, H. Sato, R. Kadono
Local electronic structure of dilute hydrogen in β−MnO2
Phys. Rev. B, 103 155121 (2021).
235 T. Omi, Y. Watanabe, N. Abe, H. Sagayama, A. Nakao, K. Munakata,
Y. Tokunaga, T. Arima
Antiferromagnetic-to-ferrimagnetic phase transition with large electric-polarization change in a frustrated polar magnet CaBaCo4O7
Phys. Rev. B, 103 184412 (2021).
236 P. Wu, K. Xia, K. Peng, T. Honda, K. Ikeda, F. Liu, P. Vallobra, F. Fan,
J. Song, D. Zhang, F. Yu, J. Ying, F. Zhu, T. Otomo, T. Kamiyama, W.
Zhao
Strong anharmonicity in tin monosulfide evidenced by local distortion, high-energy optical phonons, and anharmonic potential
Phys. Rev. B, 103 195204 (2021).
237 W. Chen, X. Li, Z. Hu, Z. Hu, L. Yue, R. Sutarto, F. He, K. Iida, K.
Kamazawa, W. Yu, X. Lin, Y. Li
Spin-orbit phase behavior of Na2Co2TeO6 at low temperatures
Phys. Rev. B, 103 L180404 (2021).

227 L. A. Ma, R. Palm, E. Nocerino, O. K. Forslund, N. Matsubara, S. P.
Cottrell, K. Yokoyama, A. Koda, J. Sugiyama, Y. Sassa, M. Mansson,
R. Younes
Na-ion mobility in P2-type Na0.5MgxNi0.17−xMn0.83O2 (0 ≤ x ≤ 0.07) fromelectrochemical and muon spin relaxation studies
Phys. Chem. Chem. Phys., 23 24478-24486 (2021).

238 M. Hiraishi, K. M. Kojima, H. Okabe, A. Koda, R. Kadono, J. Wu, Y. Lu,
H. Hosono
Anomalous diamagnetism of electride electrons in transition metal
silicides
Phys. Rev. B, 103 L241101 (2021).

228 S. Kanda, Y. Fukao, Y. Ikedo, K. Ishida, M. Iwasaki, D. Kawall, N.
Kawamura, K. M. Kojima, N. Kurosawa, Y. Matsuda, T. Mibe, Y.
Miyake, S. Nishimura, N. Saito, Y. Sato, S. Seo, K. Shimomura, P.
Strasser, K. S. Tanaka, T. Tanaka, H. A. Torii, A. Toyoda, Y. Ueno
New precise spectroscopy of the hyperfine structure in muonium
with a high-intensity pulsed muon beam
Phys. Lett. B, 815 136154 (2021).

239 N. Higa, T. U. Ito, M. Yogi, T. Hattori, H. Sakai, S. Kambe, Z. Guguchia,
W. Higemoto, M. Nakashima, Y. Homma, A. Nakamura, F. Honda,
Y. Shimizu, D. Aoki, M. Kakihana, M. Hedo, T. Nakama, Y. Ōnuki, Y.
Tokunaga
Critical slowing-down and field-dependent paramagnetic fluctuations in the skyrmion host EuPtSi: μSR and NMR studies
Phys. Rev. B, 104 045145 (2021).

229 S. Nishimura, H. A. Torii, Y. Fukao, T. U. Ito, M. Iwasaki, S. Kanda,
K. Kawagoe, D. Kawall, N. Kawamura, N. Kurosawa, Y. Matsuda,
T. Mibe, Y. Miyake, N. Saito, K. Sasaki, Y. Sato, S. Seo, P. Strasser,
T. Suehara, K. S. Tanaka, T. Tanaka, J. Tojo, A. Toyoda, Y. Ueno, T.
Yamanaka, T. Yamazaki, H. Yasuda, T. Yoshioka, K. Shimomura
Rabi-oscillation spectroscopy of the hyperfine structure of muonium
atoms
Phys. Rev. A, 104 L02080 (2021).

240 M. Matsuura, Y. Fujiwara, H. Moriwake, K. Ohara, Y. Kawakita
Microscopic dynamics of lithium diffusion in single crystal of the solid-state electrolyte La2/3−xLi3xTiO3 (x = 0.13) studied by quasielastic
neutron scattering
Phys. Rev. B, 104 094305 (2021).

230 R. Kitamura, S. Bae, S. Choi, Y. Fukao, H. Iinuma, K. Ishida, N.
Kawamura, B. Kim, Y. Kondo, T. Mibe, Y. Miyake, M. Otani, G. P.
Razuvaev, N. Saito, K. Shimomura, P. Strasser
Development of negative muonium ion source for muon acceleration
Phys. Rev. Accel. Beams, 24 33403 (2021).
231 P. Miao, Z. Tan, S. Lee, Y. Ishikawa, S. Torii, M. Yonemura, A. Koda, K.
Komatsu, S. Machida, A. Sano-Furukawa, T. Hattori, X. Lin, K. Li, T.
Mochiku, R. Kikuchi, C. Kawashima, H. Takahashi, Q. Huang, S. Itoh,
R. Kadono, Y. Wang, F. Pan, K. Yamauchi, T. Kamiyama
Origin of magnetvolume effect in a cobaltite
Phys. Rev. B, 103 094302 (2021).

196

232 J. Sugiyama, W. Higemoto, D. Andreica, O. K. Forslund, E. Nocerino,
M. Månsson, Y. Sassa, R. Gupta, R. Khasanov, H. Ohta, H. Nakamura
Pressure dependence of ferromagnetic phase boundary in BaVSe 3
studied with high-pressure μ+SR
Phys. Rev. B, 103 104418 (2021).

241 Y. Shangguan, S. Bao, Z.-Y. Dong, Z. Cai, W. Wang, Z. Huang, Z. Ma,
J. Liao, X. Zhao, R. Kajimoto, K. Iida, D. Voneshen, S.-L. Yu, J.-X. Li, J.
Wen
Evidence for strong correlations at finite temperatures in the dimerized magnet Na2Cu2TeO6
Phys. Rev. B, 104 224430 (2021).
242 M. Miyajima, F. Astuti, T. Fukuda, M. Kodani, S. Iida, S. Asai, A.
Matsuo, T. Masuda, K. Kindo, T. Hasegawa, T. C. Kobayashi, T.
Nakano, I. Watanabe, T. Kambe
Spin-gap formation due to spin-Peierls instability in π-orbitalordered NaO2
Phys. Rev. B, 104 L140402 (2021).
243 W. Hong, L. Liu, C. Liu, X. Ma, A. Koda, X. Li, J. Song, W. Yang, J. Yang,
P. Cheng, H. Zhang, W. Bao, X. Ma, D. Chen, K. Sun, W. Guo, H. Luo,

MLF Annual Report 2021

A. W. Sandvik, S. Li
Extreme Suppression of Antiferromagnetic Order and Critical Scaling
in a Two-Dimensional Random Quantum Magnet
Phys. Rev. Lett., 126 037201 (2021).
244 T. Okumura, T. Azuma, D. A. Bennett, P. Caradonna, I-H. Chiu, W.
B. Doriese, M. S. Durkin, J. W. Fowler, J. D. Gard, T. Hashimoto, R.
Hayakawa, G. C. Hilton, Y. Ichinohe, P. Indelicato, T. Isobe, S. Kanda,
D. Kato, M. Katsuragawa, N. Kawamura, Y. Kino, K. M. Kubo, K.
Mine, Y. Miyake, K. M. Morgan, K. Ninomiya, H. Noda, G. C. O'Neil, S.
Okada, K. Okutsu, T. Osawa, N. Paul, C. D. Reintsema, D. R. Schmidt,
K. Shimomura, P. Strasser, H. Suda, D. S. Swetz, T. Takahashi, S.
Takeda, S. Takeshita, M. Tampo, H. Tatsuno, X.-M. Tong, Y. Ueno, J.
N. Ullom, S. Watanabe, S. Yamada
Deexcitation Dynamics of Muonic Atoms Revealed by High-Precision
Spectroscopy of Electronic K X rays
Phys. Rev. Lett., 127 053001 (2021).
245 M. Nagao, E.G. Kelley, A. Faraone, M. Saito, Y. Yoda, M. Kurokuzu, S.
Takata, M. Seto, P.D. Butler
Relationship between viscosity and acyl tail dynamics in lipid
bilayers
Phys. Rev. Lett., 127 078102 (2021).
246 K. Hagiwara, M. Ishikado, M. Horio, K. Koshiishi, S. Nakata, S. Ideta,
K. Tanaka, K. Horiba, K. Ono, H. Kumigashira, T. Yoshida, S. Ishida,
H. Eisaki, S. Shamoto, A. Fujimori
Superconducting gap and pseudogap in the surface states of theiron-based superconductor PrFeAsO1−y studied by angle-resolved
photoemission spectroscopy
Phys. Rev. Research, 3 043151 (2021).
247 Y. Hirano, S. Yamamoto, N. Kawamura, K. Ninomiya
Position distribution calculation of annihilation radiations andbremsstrahlung x rays in water during irradiation of positive muons:a Monte Carlo simulation study
Phys. Scr., 96 025302 (2021).
248 O. K. Forslund, D. Andreica, H. Ohta, M. Imai, C. Michioka, K.
Yoshimura, M. Månsson, J. Sugiyama
Co-existence of short- and long-range magnetic order in LaCo2P2
Phys. Scr., 96 125864-1 (2021).
249 A. D. Pant, K. Ishida, N. Kawamura, S. Matoba, A. Koda, S. Nishimura,
K. Shimomura
Study of muonium behavior in n-type silicon for generation of ultra
cold muonium in vacuum
Physica B Condens. Matter., 613 412997 (2021).
250 Y. Zhai, P. Luo, M. Nagao, K. Nakajima,T. Kikuchi,Y. Kawakita, P. A.
Kienzle, Y Z, A. Faraone
Relevance of hydrogen bonded associates to the transport properties and nanoscale dynamics of liquid and supercooled 2-propanol
Phys. Chem. Chem. Phys.s, 23 7220-7232 (2021).
251 T. Hayashida, Y. Uemura, K. Kimura, S. Matsuoka, M. Hagihala, S.
Hirose, H. Morioka, T. Hasegawa, T. Kimura
Phase transition and domain formation in ferroaxial crystals
Phys. Rev. Mater., 5 124409 (2021).
252 S. Shamoto, H. Yamauchi, K. Ikeuchi, R. Kajimoto, J. Ieda
Broken C4 symmetry in the tetragonal state of uniaxial strained
BaCo0.9Ni0.1S1.9
Phys. Rev. Res., 3 013169 (2021).
253 S. Hasegawa, S. Hayashida, S. Asai, M. Matsuura, Z. Igor, T. Masuda
Nontrivial temperature dependence of magnetic anisotropy in multiferroics Ba2MnGe2O7
Phys. Rev. Res., 3 L032023 (2021).
254 T. Maeda, M. Kitagawa, A. Hotta
Degradation of thermoresponsive laponite/PEG-b-PLGAMLF Operations in 2021

nanocomposite hydrogels controlled by blending PEG-b-PLGA diblock copolymers with different PLGA molecular weights
Polym. Degrad. Stab., 187 109535 (2021).
255 S. Hiroshige, H. Minato, Y. Nishizawa, Y. Sasaki, T. Kureha, M.
Shibayama, K. Uenishi, T. Takata, D. Suzuki
Temperature-dependent relationship between the structure andmechanical strength of volatile organic compound-free latex
films prepared from poly(butyl acrylate-co-methyl methacrylate)microspheres
Polym. J., 53 345 (2021).
256 J.-H. Hong, M. Totani, D. Kawaguchi, N. L. Yamada, H. Matsuno, K.
TanakaPoly[oligo(2-ethyl-2-oxazoline) methacrylate] as a surface modifier
for bioinertness
Polym. J., 53 643-653 (2021).
257 G. Ichikawa, Y. Fuwa, T. Hasegawa, M. Hino, K. Hirota, T. Ino, Y.
Iwashita, M. Kitaguchi, J. Koga, S. Matsuzaki, K. Mishima, T. Mogi,
K. Morikawa, H. Okabe, H. Otono, Y. Seki, D. Sekiba, T. Shima, H.
Shimizu, H. Shimizu, N. Sumi, H. Sumino, S. Yamashita, K. Yano, T.
Yoshioka
Neutron lifetime experiment with pulsed cold neutrons at J-PARC
Pos. Proc. Sci. (PANIC2021), 457 (2021).
258 T. Mogi, T. Hasegawa, K. Hirota, G. Ichikawa, S. Ieki, T. Ino, Y.
Iwashita, S. Kajiwara, Y. Kato, M. Kitaguchi, R. Kitahara, J. Koga, S.
Makise, S. Matsuzaki, K. Mishima, K. Morikawa, N. Nagakura, H.
Okabe, H. Otono, Y. Seki, D. Sekiba, T. Shima, H. E. Shimizu, H. M.
Shimizu, Y. Sugisawa, N. Sumi, H. Sumino, T. Tanabe, T. Tomita, H.
Uehara, T. Yamada, S. Yamashita, K. Yano, T. Yoshioka
Improvement of systematic uncertainties for the neutron lifetime experiment at J-PARC
Pos. Proc. Sci. (PANIC2021), 458 (2021).
259 S. Ishida, D. Kagerbauer, S. Holleis, K. Iida, K. Munakata, A. Nakao,
A. Iyo, H. Ogino, K. Kawashima, M. Eisterer, H. Eisaki
Superconductivity-driven ferromagnetism and spin manipulation
using vortices in the magnetic superconductor EuRbFe4As4
Proc. Natl. Acad. Sci. USA, 118 e2101101118 (2021).
260 K. Akutsu, M. Sahara, M. Ueda, T. Niizeki, M. Yoshii, T. Sugiyama, N.
Eguchi, T. Wada
Development of new waterproof thin-layers for the magnetic alloy
core: structural studies using neutron reflectometry
Proc. of the 18th Annual Meeting of Particle Accelerator Society ofJapan, August 9-11, 2021, Takasaki, Japan, 600 (2021).
261 K. Haga, H. Kogawa, T. Naoe, T. Wakui, E. Wakai, M. Futakawa
Development of the high-power spallation neutron target of J-PARC
Proc. The 19th International Topical Meeting on Nuclear Reactor
Thermal Hydraulics (NURETH-19), Log nr.: 3392 (2021).
262 K. S. Tanaka, M. Iwasaki, O. Kamigaito, S. Kanda, N. Kawamura, Y.
Matsuda, T. Mibe, S. Nishimura, N. Saito, N. Sakamoto, S. Seo, K.
Shimomura, P. Strasser, K. Suda, T. Tanaka, H. A. Torii, A. Toyoda, Y.
Ueno, M. Yoshida
Development of microwave cavities for measurement of muonium
hyperfine structure at J-PARC
Prog. Theor. Exp. Phys., 2021 053C01 (2021).
263 Y. Onuki, S. SatoIn Situ Observation for Deformation-Induced Martensite
Transformation during Tensile Deformation of SUS 304 StainlessSteel by Using Neutron Diffraction PART II: Transformation andTexture Formation Mechanisms
Quantum Beam Sci., 5 6 (2021).
264 F. Grazzi, C. Cialdai, M. Manetti, M. Massi, M. P. Morigi, M. Bettuzzi,
R. Brancaccio, F. Albertin, T. Shinohara, T. Kai, A. Fedrigo, A. Di
Giovanni, F. Arneodo, R. Torres, O. Al‑Ketan, J. Elhashemi, F.

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MLF Annual Report 2021

Taccetti, L. Giuntini
A multi‑technique tomography‑based approach for non‑invasive
characterization of additive manufacturing components in view of
vacuum/UHV applications: preliminary results
Rend. Lincei. Sci. Fis. Nat., (2021).
265 Y. Nishizawa, H. Minato, T. Inui, I. Saito, T. Kureha, M. Shibayama, T.
Uchihashi, D. Suzuki
Nanostructure and thermoresponsiveness of poly(N-isopropyl
methacrylamide)-based hydrogel microspheres prepared via aqueous free radical precipitation polymerization
RSC Adv., 11 13130 (2021).
266 M. Uchida, S. Sato, H. Ishizuka, R. Kurihara, T. Nakajima, Y.
Nakazawa, M. Ohno, M. Kriener, A. Miyake, K. Ohishi, T. Morikawa,
M. S. Bahramy, T. Arima, M. Tokunaga, N. Nagaosa, M. Kawasaki
Above-ordering-temperature large anomalous Hall effect in a triangular-lattice magnetic semiconductor
Sci. Adv., 7 abl5381 (2021).
267 Y. Ohtsuka, N. Kanazawa, M. Hirayama, A. Matsui, T. Nomoto, R.
Arita, T. Nakajima, T. Hanashima, V. Ukleev, H. Aoki, M. Mogi, K.
Fujiwara, A. Tsukazaki, M. Ichikawa, M. Kawasaki, Y. Tokura
Emergence of spin-orbit coupled ferromagnetic surface state derived
from Zak phase in a nonmagnetic insulator FeSi
Sci. Adv., 7 eabj0498 (2021).
268 Y. Hao, H. Wo, Y. Gu, X. Zhang, Y. Gu, S. Zheng, Y. Zhao, G. Xu, J. W.
Lynn, K. Nakajima, N. Murai, W. Wang, J. Zhao
Field-tuned magnetic structure and phase diagram of the honeycomb magnet YbCl3
Sci. China Phys. Mech. Astron., 64 237411 (2021).
269 Y. Su, K. Oikawa, T. Shinohara, T. Kai, T. Horino, O. Idohara, Y. Misaka,
Y. Tomota
Neutron Bragg-edge transmission imaging for microstructure andresidual strain in induction hardened gears
Sci. Rep., 11 4155 (2021).
270 M. Akamatsu, K. Kobayashi, H. Iwase, Y. Sakaguchi, R. Tanaka, K.
Sakai, H. Sakai
Rapid controlled release by photo-irradiation using morphologicalchanges in micelles formed by amphiphilic lophine dimers
Sci. Rep., 11 10754 (2021).
271 M. Kofu, R. Watanuki, T. Sakakibara, S. Ohira-Kawamura, K.
Nakajima, M. Matsuura, T. Ueki, K. Akutsu, O. Yamamuro
Spin glass behavior and magnetic boson peak in a structural glass ofa magnetic ionic liquid
Sci. Rep., 11 12098 (2021).
272 R. Iizuka-Oku, H. Gotou, C. Shito, K. Fukuyama, Y. Mori, T. Hattori, A.
Sano-Furukawa, K. Funakoshi, H. Kagi
Behavior of light elements in iron-silicate-water-sulfur system during
early Earth's evolution
Sci. Rep., 11 12632 (2021).
273 M. Busi, N. Kalentics, M. Morgano, S. Griffiths, A. S. Tremsin, T.
Shinohara, R. Logé, C. Leinenbach, M. Strobl
A parametric neutron Bragg edge imaging study of additively manufactured samples treated by laser shock peening
Sci. Rep., 11 14919 (2021).
274 H. Aoki, Y. Liu, T. Yamashita
Deep learning approach for an interface structure analysis with alarge statistical noise in neutron reflectometry
Sci. Rep., 11 22711 (2021).
275 M.-S. Lee, T. Kawasaki, T. Yamashita, S. Harjo, Y.-T. Hyun, Y. Jeong,
T.-S. Jun
In-situ neutron diffraction study of lattice deformation behaviour ofcommercially pure titanium at cryogenic temperature

198

Sci. Rep., 12 3719 (2021).
276 H. Nakao, Y. Kimura, A. Sakai, K. Ikeda, M. Nakano
Development of membrane-insertable lipid scrambling peptides: A
time-resolved smallangle neutron scattering study
Struct. Dyn., 8 24301 (2021).
277 T. D. Vu, H. Shishido, K. Kojima, T. Koyama, K. Oikawa, M. Harada,
S. Miyajima, T. Oku, K. Soyama, K. Aizawa, M. Hidaka, S. Suzuki, M.
Tanaka, A. Malins, M. Machida, T. Ishida
Homogeneity of neutron transmission imaging over a large sensitive
area with a four-channel superconducting detector
Supercond. Sci. Technol., 34 15010 (2021).
278 S. Harjo, T. Kawasaki, N. Tsuchida, S. Morooka, W. Gong
Relation between Intergranular Stress in Austenite and Martensitic
Transformation in TRIP Steels Revealed by Neutron Diffraction
Tetsu to Hagane, 107 887-896 (2021).
279 H. Yoshida, A. Yamamoto, S. Hosokawa, S. Yamazoe, S. Kikkawa, K.
Hara, M. Nakamura, K. Kamazawa, T. Tanaka
Observation of Adsorbed Hydrogen Species on Supported Metal
Catalysts by Inelastic Neutron Scattering
Top. Catal., 64 660-671 (2021).
280 N. Yamashita, T. Hirayama, N. L. Yamada, H. Watanabe, K. Onodera,
T. SatoHighly Swollen Adsorption Layer Formed by Polymeric Friction
Modifier Providing Low Friction at Higher Temperature
Tribol. Lett., 69 65 (2021).
281 K. Sakai, Y. Ayame, Y. Iwanami, N. Kimura, Y. Matsumoto
Observation of Grease Fluidity in a Ball Bearing Using Neutron
Imaging Technology
Tribology Online, 16 146-150 (2021).
282 A. Yoshiasa, T. Tobase, H. Arima-Osonoi, K. Funakoshi, O. Ohtaka, T.
Nakatani, S. Kohara
High-temperature diffraction experiments and phase diagram ofZrO2 and ZrSiO4
Z. Naturforsch. B J. Chem. Sci., (2021).
283 J. Sugiyama, K. Ohishi, O. K. Forslund, M. Månsson, S. P. Cottrell, A.
D. Hillier, K. Ishida
How Li diffusion in spinel Li[Ni1/2Mn3/2]O4 is seen with μ±SR
Z. Phys. Chem., (2021).

MLF Annual Report 2021

Editorial Board

Editorial Board - MLF Annual Report 2021

Chief Editor

Shoichiro Nishimura

Maiko Kofu
Neutron Science Section

Muon Science Section

Kazuki Iida

Yuhua SuCROSSTechnology Development Section

Yoshihiro Matsumoto

Dai Yamazaki

CROSS

Neutron Instrumentation Section

Takashi Naoe

Naomine Yano

Neutron Source Section

Ibaraki University

Takashi Ino

Misono Fujii

Neutron Science Section

Muon Science Section

199

J-PARC

Japan Proton Accelerator Research Complex

High Energy Accelerator Research Organization (KEK)
Japan Atomic Energy Agency (JAEA)

http://j-parc.jp/
Materials and Life Science Division
J-PARC Center

https://mlfinfo.jp/en
Comprehensive Research Organization for Science and Society

https://neutron.cross.or.jp/en

J-PARC 22-02