20

HiSORACTIVITY REPORT
2020

Hiroshima Synchrotron Radiation Center, HiSOR
Hiroshima University

Edited by K. Matsuo
The annual report is available from
Hiroshima Synchrotron Radiation Center, Hiroshima University
Kagamiyama 2-313, Higashi-Hiroshima 739-0046, JAPAN
Phone: +81-82-424-6293
Fax: +81-82-424-6294
e-mail: hisor@hiroshima-u.ac.jp
URL: http://www.hsrc.hiroshima-u.ac.jp

Preface
The Hiroshima Synchrotron Radiation Center was inaugurated in 1996, as part of theacademic policies of the Ministry of Education, Culture, Sports, Science, and Technology(MEXT), Japan. A compact 700MeV electron-storage ring, called HiSOR (this center is often
referred to as HiSOR), produces synchrotron radiation in the range of ultraviolet and soft x-ray
range. The mission of HiSOR is to promote advanced research in the field of condensed matterphysics including interdisciplinary fields using synchrotron radiation, as well as to develop
human resources in the international research environment established inside the national
university. HiSOR has been authorized as a “Joint Usage / Research Center” by the MEXT
since FY2010.
In FY2020, Dr. Shiv Kumar has been appointed as an Assistant Professor to promote thehigh-resolution ARPES study of topological materials. Dr. Hiroshi Miyauchi from KEK has
joined Prof. Katoh's group to develop vacuum systems for a compact storage ring.
Due to the COVID-19 pandemic, collaborators outside the university could not come mostof the time. Therefore, we canceled the call for proposals (type G) for the 2020 period B (Sep.
1, 2020 - Mar. 31, 2021). The number of accepted proposals was reduced to 78 in total (130
proposals in FY2019), including 22 overseas proposals. Our international users could not comefrom early 2020 till now. Our staff members have done 16 proposals on behalf of international
collaborators.
Even in the difficult situation, we have published 57
59 refereed papers in 2020, which
exceeds the previous year's 42. About 59
58% of the published papers are written by international
collaboration. The ratio of the top10% paper (highly cited papers in the SCI-indexed journals)
becomes 13% for the period 2016-2020 (3rd mid-term objective period), indicating a qualityof the published papers.
We hosted several online events; KEK-day (Dec. 19, 2020, 134 participants including 65
students from senior high schools and national technical colleges), The 34th annual joint
symposium of the Japanese Society of Synchrotron Radiation Research (Jan. 8-10, 2021, 587
participants), and the 25th Hiroshima International Symposium on Synchrotron Radiation (71participants, 11 overseas participants). To introduce our facility to junior and senior highstudents under the pandemic situation, we have developed content using virtual reality (VR)devices. We have sent 16 VR devices to the Hasumi Junior High in Shimane prefecture, andhold an online VR tour of the facility.

－i－In closing, I would like to thank all the staff members for their great efforts to operate
HiSOR and to maintain and advance experimental stations. I also want to thank our students
and collaborators for their excellent scientific achievements, making full use of ourfacilities. Finally, I deeply appreciate the continued supports of Hiroshima University andthe MEXT.

July 2021

Kenya Shimada
Director of Hiroshima Synchrotron Radiation Center－ ii －

Table of Contents－ iii －

－ iv －

Tabie of Contents
Preface

Current Status of HiSOR
Status of the HiSOR storage ring…………………………………………………………………… 1
Beamlines…………………………………………………………………………………………… 5

Research Activities―Accelerator Studies―
Developments of Virtual Reality Contents for Accelerator Research and Educations………… 9
T. Iwao, M. Shimada, M. Katoh
Design Study on a Compact Storage Ring Light Source with Superconducting
Bending Magnets……………………………………………………………………………………11
K. Hiramatsua, M. Shimada, M. Katoh―Synchrotron Radiation Experiments―
Unveiling orbital characteristics of surface states in HfSiS………………………………………13
X. X. Wang, J. H. Chen, M. T. Zheng, M. Novak, F. Orbanić,
E. F. Schwier, K. Sumida, T. Yoshikawa, M. Nurmamat, K. Shimada, A. Kimura
Effect of spin-orbit coupling on bulk bands of the non-symmorphic semimetal Hf1-xZrxSiS……15

X. X. Wang, J. H. Chen, M. T. Zheng, M. Novak, F. Orbanić,
E. F. Schwier, K. Sumida, T. Yoshikawa, M. Nurmamat, K. Shimada, A. Kimura
Effect of spin-orbit coupling on surface states of the non-symmorphic semimetal Hf1-xZrxSiS……17
X. X. Wang, J. H. Chen, M. T. Zheng, M. Novak, F. Orbanić,
E. F. Schwier, K. Sumida, T. Yoshikawa, M. Nurmamat, K. Shimada, A. Kimura
ARPES study of the electronic structure of HfSiS with variable polarized light………………19
X. X. Wang, J. H. Chen, M. T. Zheng, M. Novak, F. Orbanić,
E. F. Schwier, K. Sumida, T. Yoshikawa, M. Nurmamat, K. Shimada, A. Kimura－v－

Superconductivity and Fermi-surface nesting in the candidate Dirac semimetal NbC…………21
D. Ya, D. Geng, Q. Gao, Z. Cui, C. Yi, Y. Feng, C. Song, H. Luo, M. Yang, M. Arita, S. Kumar,
E. F. Schwier, K. Shimada, L. Zhao, K. Wu, H. Weng, L. Chen, X. J. Zhou, Z. Wang, Y. Shi, B. Feng
Investigations on Angle-resolved Photoemission Spectroscopy and Pressure-induced Transport
Properties of BiSbTe3 Topological Insulator…………………………………………………………24
S. Kumar, V. K. Gangwar, M. Singh, L. Ghosh, Y. Zhang, P. Shahi, M. Muntwiler, S. Patil,
K. Shimada, Y. Uwatoko, S. Chatterjee
Study of the band structure of LaAgSb2 by angle-resolved photoemission spectroscopy………26
T. Yoshikawa, Y. Kitayama, H. Tanida, E. F. Schwier, K. Shimada, A. Kimura
Self-energy Analysis of High-Tc Cuprate Superconductor La2-xSrxCuO4…………………………28
H. Oda, H. Iwasawa, S. Ozawa, A. Kimura, R. Yano, S. Kashiwaya, T. Sasagawa,E. F. Schwier, K. Shimada
Strain Induced Metal-Insulator Transition in Mott Insulator Ca2RuO4…………………………30
T. Miyashita, H. Iwasawa, H. Oda, S. Ozawa, A. Ino, F. Nakamura, A. Kimura, M. Arita,
E. F. Schwier, K. Shimada
Experimental observation of Dirac cones in artificial graphene lattices…………………………31
S. Yue, H. Zhou, D. Geng, Z. Sun, M. Arita, K. Shimada, P. Cheng, L. Chen, S. Meng,
K. Wu, B. Feng
Topological electronic structure in the antiferromagnet HoSbTe………………………………34
S. Yue, Y. Qian, M. Yang, D. Geng, C. Yi, S. Kumar, K. Shimada, P. Cheng, L. Chen,
Z. Wang, H. Weng, Y. Shi, K. Wu, B. Feng
Electronic structure of chiral IrGe4 studied by angle-resolved photoemission spectroscopy… 37
T. Mizokawa, T. Shimaiwa, Y. Akabane, N. L. Saini, Y. Chiba, R. Higashinaka, T. D. Matsuda,
Y. Aoki, E. F. Schwier, S. Kumar, K. Shimada
Observation of spin-momentum-layer locking in a centrosymmetric crystal……………………39
K. Zhang, S. Kumar, E. F. Schwier, K. Miyamoto, T. Okuda, K. Shimada－ vi －

Low-energy electron-boson couplings in Sr2RuO4…………………………………………………42
S. Ozawa, H. Iwasawa, H. Oda, T. Sugiyama, A. Kimura, S. Kumar, Y. Yoshida, I. Hase,
Y. Aiura, K. Shimada
Ultrathin Ferromagnetic Films on Spin-Orbit-Influenced Metals: Interplay between Exchange
and Spin-Orbit Interaction…………………………………………………………………………44
M. Holtmann, P. J. Grenz, S. Kumar, E. F. Schwier, T. Okuda, M. Donath
Half-Magnetic Topological Insulator with Magnetization-Induced Dirac Gap at a Selected
Surface………………………………………………………………………………………………46
R. Lu, S. Kumar, Y. Wang, M. Zeng, Y.-J. Hao, X.-M. Ma, Z. Hao,
K. Zhang, W. Mansuer, C. Liu, K. Deng, K. Shimada, E. F. Schwier,
C. Liu, Q. Liu, C. Chen
ARPES Study on low dimensional chiral Dirac material CoNb3S6………………………………48
K. Deng, S. Kumar, Y. Wang, C. Liu, K. Shimada, C. Chen
Termination-Dependent Surface States of Cr2O3 on Graphene Covered Ni(111) Substrate……51
X. Hou, S. Kumar, M. Sawada
High-resolution ARPES of heavily overdoped Bi2201: evaluation of coupling parameters……53
Y. Miyai, K. Ishiba, S. Kumar, T. Kurosawa, M. Oda, K. Shimada
Topological Surface State in Sb, Te, and Se Based Single Crystals………………………………55
Amit Kumar, Shiv Kumar, Gopi Govindhan, Aravinth Kumar, Anandha B. Govindan,
K. ShimadaBand Dispersion Unique to the Cobalt Intercalation in the Noncentrosymmetric Antiferromagnet
CoNb3S6………………………………………………………………………………………………57
H. Tanaka, S. Okazaki, K. Kuroda, Shiv Kumar, T. Sasagawa, T. Kondo
Development of On-site Cleaning Method of Carbon Contamination with Atomic Hydrogen 2……59
T. Tokushima, M. Niibe, T. Kono, Y. Horikawa, H. YoshidaComparison of soft X-ray absorption spectra of transition metal sulfates………………………61
K. Baba, H. Yoshida－ vii －

Kondo resonance peak in the photoemission spectra of YbAgCu4………………………………63
H. Anzai, R. Tawara, Y. Kikuchi, H. Sato, M. Arita, R. Takaaze, K. T. Matsumoto, K. Hiraoka
Electronic Structures and Chemical Natures of Inhomogeneous Gd-TM (TM = Co, Ni, and Cu)
Metallic Glasses………………………………………………………………………………………65
S. Hosokawa, J. R. Stellhorn, H. Sato, J. Jiang, H. Kato
Conduction-Band Electronic States of Gd-TM Metallic Glass Alloys Having Thermal
Rejuvenation Effect…………………………………………………………………………………67
S. Hosokawa, J. R. Stellhorn, H. Sato, J. Jiang, H. Kato
Low-Energy Photoemission Study of YbCu5-xAlx…………………………………………………69
A. Kano, R. Kamimori, T. Matsumoto, H. Sato, M. Arita, N. Tsujii
Electronic structure of NaSn2As2 studied by angle-resolved photoemission spectroscopy……70
T. Mizokawa, Y. Akabane, T. Shimaiwa, N. L. Saini, Y. Goto, Y. Mizuguchi, M. Arita
Disentangling spin and orbital texture of surface states of HfSiS………………………………72
X. X. Wang, J. H. Chen, M. T. Zheng, M. Novak, F. Orbanić, K. Sumida, T. Yoshikawa,
M. Nurmamat, K. Miyamoto, T. Okuda, A. Kimura
Variable surface state splitting of DNL semimetal MSiS (X=Zr, Hf) by tuning SOC couplingstrength………………………………………………………………………………………………74
X. X. Wang, J. H. Chen, M. T. Zheng, M. Novak, F. Orbanić, K. Sumida, T. Yoshikawa,
M. Nurmamat, K. Miyamoto, T. Okuda, A. KimuraIn-situ evaluation of spin polarizations and band dispersions of Co2MnSi thin film……………76
M. Kakoki, K. Sumida, T. Kono, K. Goto, K. Miyamoto, T. Okuda, Y. Sakuraba,
K. Hono, A. Kimura
Observation of Rashba splitting in high-Tc cuprate superconductor YBa2Cu3O7………………78
H. Iwasawa, T. Miyashita, T. Yoshikawa, A. Kimura, K. Miyamoto, T. Okuda
Spin-resolved ARPES study of Heusler-type Co2MnGa exhibiting gigantic anomalous
Nernst effect…………………………………………………………………………………………81
K. Sumida, Y. Sakuraba, K. Masuda, T. Kono, M. Kakoki, K. Goto, K. Miyamoto, Y. Miura,
T. Okuda, A. Kimura－ viii －Spin-polarized tiled Weyl cone in Co2MnGa thin film probed by spin- and angleresolved ARPES……………………………………………………………………………………83
K. Sumida, Y. Sakuraba, K. Masuda, T. Kono, M. Kakoki, K. Goto, K. Miyamoto, Y. Miura,
T. Okuda, A. Kimura
Spin-resolved ARPES study of a charge density wave compound NbTe4………………………85
M. Sakano, N. Mitsuishi, M. Chiba, K. Miyamoto, T. Okuda, T. Sasagawa, K. Ishizaka
Probing a New Type of Spin-splitting Effect in Antiferromagnets………………………………87
Y. Zhu, K. Zhang, X. Ma, K. Shimada, T. Okuda, Chang Liu
Observation of Topological States in Ca2Pd3Sb4 Superconductor………………………………89
S. Wu, K. Shiraishi, K. Miyamoto, T. Okuda, G. Xu, X. Zhou
Efficient photocatalytic activation of C-H bonds by spatially controlled chlorine and titanium
on the silicate layer…………………………………………………………………………………91
N. Tsunoji, S. Hayakawa
Structure of a Novel Amorphous Organic-Inorganic Hybrid Tin Cluster Exhibiting Nonlinear
Optical Effects by Low-Energy XAFS Measurements……………………………………………93
J. R. Stellhorn, K. Yagi, S. Hayakawa, B. Paulus, B. D. Klee,
W.-C. Pilgrim, S. Dehnen
Polarization dependent sulfur K-edge XAFS measurements of P3HT thin films fordetermination of film orientations with the improved sensitivity………………………………95
H. Yoshimoto, J. R. Stellhorn, K. Komaguchi, S. Hayakawa
Evaluation of the Self-healing Bio-assisted Cement-treated Clay with XAFS…………………97
S. Ikoma, J. Nakayenga, T. Hata, S. Hayakawa
Degradation Analysis of Automotive Oil with ZnDTP Additive by Fluorescence yield
XAFS method………………………………………………………………………………………99
S. Mineoi, K. Momosaki, H. Sumida, S. Hayakawa－ ix －

Effects of Mono-Saccharides on Structural Stabilization of Apo-Myoglobin Studied by
Synchrotron-Radiation Circular-Dichroism Spectroscopy…………………………………… 101
T. Shimizu, A. Uomi, M. Kumashiro, Y. Izumi, K. Matsuo
Study of Membrane-Bound Conformation and Pore Formation of Magainin2 using
Vacuum-Ultraviolet Circular-Dichroism Spectroscopy………………………………………… 103
R. Tsuji, M. Kumashiro, K. Matsuo
Effect of Concentration on the Thermal Denaturation of Collagen…………………………… 104
Y. Maki, K. Matsuo
Electronic Relaxation Process in Fluorinated Aromatic Monolayers Studied by Core-Excited
Ion Desorption…………………………………………………………………………………… 106
K. Yamamoto, S. Wada
Inner Shell Excitation Spectroscopy of Gold Nanoparticles Coated with Aromatic Molecules…… 108
S. Tendo, Y. Okada, S. Wada
Soft X-ray Polarization Measurement and Evaluation at HiSOR BL-13 Using Electron
Orbitally Oriented Samples……………………………………………………………………… 110
M. Tabuse, S. Wada
X-ray Absorption Spectroscopy of Self-assembled Monolayers Prepared on a Thin Gold Wire…… 112
Y. Hikosaka, S. Wada
Growth mode and interface structure of Co ultrathin films evaporated on h-BN/Ni(111)…… 114
W. Nishizawa, T. Mayumi, M. Sawada

Appendices
Organization……………………………………………………………………………………… 115
List of publications………………………………………………………………………………… 120
List of accepted research proposals……………………………………………………………… 127
Symposium, Workshop…………………………………………………………………………… 132
The 25th Hiroshima International Symposium on Synchrotron Radiation………………………… 133
Plan of the Building……………………………………………………………………………… 135
Location…………………………………………………………………………………………… 136－x－Current Status of HiSOR

Status of the HiSOR storage ring
1. Introduction
The HiSOR is a synchrotron radiation (SR) source of Hiroshima Synchrotron Radiation
Center, Hiroshima University, established in 1996. It is a compact racetrack-type storage ring
having 21.95 m circumference and 700MeV electron energy. It has two 180-degree
normal-conducting bending magnets which generate a strong magnetic field of 2.7 T. Due tothis compact configuration, the natural emittance of the electron beam is 400 nm-rad, which israther large compared with other synchrotron light sources. It has two straight sections, where
two insertion devices, a linear undulator and an APPLE-II undulator, are operational. The
most outstanding advantage of the facility lies in good combination with state-of-the-art
beamlines (BL’s) for high-resolution photoelectron spectroscopy in the photon energy ranges
between VUV and soft X-ray. Moreover, the high field bending magnets produce synchrotron
radiation in wide spectral range including tender X-rays, which can be powerful probes invarious research fields.
The principal parameters of HiSOR are shown in Table 1. Major parameters of theseundulators are listed in Table 2. The photon energy spectra of the SR from HiSOR are shownin Figure 1.
Table 1: Main parameters of the HiSOR Storage ring.
CircumferenceType
Bending radiusBeam energy at Injection
at Storage
Magnetic field at Injection
at Storage
Injector
Betatron tune (x, y)RF frequency
Harmonic number
RF voltage
Stored current (nominal)
Natural emittanceBeam life time
Critical wavelength
Photon intensity (5 keV)

21.95 mRacetrack
0.87 m
150 MeV
700 MeV
0.6 T
2.7 T
150 MeV Racetrack Microtron(1.72, 1.84)
191.244 MHz
14
200 kV
300 mA
400 nmrad~10 hours@200 mA
1.42 nm1.2×1011 /sec/mr2/0.1%b.w./300mA－1－

Table 2: Main parameters of the undulators.
Linear undulator (BL-1)
Total length

2354.2 mm
57 mm
41
30-200 mm
0.41 T
Nd-Fe-B (NEOMAX-44H)

Periodic length u
Periodic number
Pole gap
Maximum magnetic field
Magnetic material
Quasi-Periodic APPLE-II

undulator (BL-9A,B)
Total length
1845 mm
78 mm
Periodic length u
Periodic number
23
Pole gap
23-200 mm
Maximum magnetic field
0.86 T (horizontal linear mode)
0.59 T (vertical linear mode)
0.50 T (helical mode)
Magnetic material
Nd-Fe-B (NEOMAX-46H)

Wave length [nm]
100

10

16

10

BL-9 QP-APPLE2(helical mode)

15

1st

1

BL-1 Linear undulator
3rd

5th

10

Ring current = 300 mA

7th peak2

2

Brilliance [Photons/sec/mrad /mm /0.1 % b.w.]

1000

BL-9 QP-APPLE2(linear mode)

14

10

Bending magnet

13

10

12

10

BL5

11

10

BL12
1

10

BL9A

BL1
BL7

BL15

BL6
BL14

100

BL3

BL13

BL11

1000

Photon energy [eV]

Figure 1: Photon energy spectra of the SR from HiSOR.

－2－

10000

2. Operation status in FY 2020
The ring is operated for users from Tuesday to Friday. Figure 2 shows an example oftypical users operation for one day. Beam injection for HiSOR is executed twice a day, ataround 9:00 and 14:30. The beam injection is normally completed within 30 minutes. The
filling beam current is about 300mA. Machine is operated for machine conditionings andstudies on Monday.
Figure 3 shows monthly operation time of HiSOR storage ring in FY 2020. HiSOR
regularly has a long-term shutdown period for maintenance works in every summer. However,in 2020, because the planned electricity outage was set in the middle of November, theshutdown was shifted to November. In addition, because of the COVID-19 infections, theoperation was canceled in May. The total user time of FY2020 achieved 1370 hours.
400

600
500
400

200

300
200

100
100
0
09:00

0
12:00

15:00

18:00

Time

Figure 2: Typical daily operation status.

Figure 3: Monthly operation time in FY 2020.

－3－

Beam life time [min]Ring current [mA]300

Figure 4: Operation time in FY 2013-2020.

－4－

Beamlines
A total of 13 beamlines has been constructed so far; three normal-incidence
monochromators, seven grazing-incidence monochromators, two double crystal
monochromators and apparatus for white beam irradiation (Fig. 1). Table 1 lists the beamlinesat present together with the main subject, energy range and monochromators.
Table 1: List of Beamlines
Beamline

SourceMonochromator

Subject

Energy range(eV)

Status

BL-1

LU

GIM

Polarization dependent
high-resolution ARPES

22-300

In use

BL-3

BM

DCM

Surface XAFS

1800-3200

In use

BL-4

BM

BL-5

BM

GIM

ARPES and PEEM

40-220

In use

BL-6

BM

GIM

Gas-phase photochemistry200-1200

In use

BL-7

BM

GIM

ARPES

20-380

In use

BL-8

BM

BL-9A

HU/LU

NIM

BL-9B

HU/LU

GIM

BL-11

BM

DCM

BL-12

BM

BL-13

White beam irradiation

ClosedBeam diagnosis

In use5-35

In use16-300

In useXAFS

2000-5000

In useNIM

VUV-CD of biomaterials

2-10

In useBM

GIM

Surface photochemistry60-1200

In use

BL-14

BM

GIM

Soft-XMCD of
nano-materials

400-1200

In use

BL-15

BM

NIM

VUV-CD of biomaterials

4-40

ClosedBL-16

BM

High-resolution
spin-resolved ARPES

Beam profile monitor

In useAt present, nine beamlines BL1, BL3, BL6, B7, BL9A, BL9B, BL11, BL12, BL13 andBL14 are opened for users. Furthermore, three offline systems, resonant inverse
photoemission spectrometer (RIPES), low-temperature scanning tunneling microscope(LT-STM) system, high-resolution angle-resolved photoemission spectrometer using
ultraviolet laser (Laser ARPES) are in operation (Fig. 2).

－5－

Fig. 1: Schematic view of the experimental hall.

－6－

Fig. 2：： Experimental stations on the beamline and offline: (a) BL-1, (b) BL-3, (c) BL-6, (d)BL-7, (e) BL-9A, (f) BL-9B, (g) BL-11, (h) BL-12, (i) BL-13, (j) BL-14, (k) RIPES (offline),(l) LT-STM (offline), (m) Laser ARPES (offline), (n) Laser spin-ARPES (offline).

－7－

Research Activities– Accelerator Studies –Developments of Virtual Reality Contents for Accelerator
Research and Educations
Takeshi Iwaoa, Miho Shimadac,a and M Katoha,baHiroshima University,1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan
Institute for Molecular Science, National Institutes of Natural Sciences, 38 Nishigo-Naka, Myodaiji,
Okazaki, 444-8585, Japanc
High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, 305-0801, Japanb

Keywords: Accelerator, Virtual Reality, Facility Tour.

The synchrotron light source, HiSOR, in Hiroshima University is compact and of low energy. The
accelerator complex consists of an injector, 150 MeV microtron, and a 700 MeV storage ring. The ring has
two undulators and 14 synchrotron radiation beamlines are operational. Because of its low energy, the ringis not constructed in a tunnel. Therefore, the visitors can see the accelerator and the beamlines directly. This
is in contrast with large facilities, where the accelerators are in tunnels, and is beneficial to learn about theaccelerators and synchrotron radiation instrumentation. Indeed, we accept many visitors, particularly fromjunior high schools and high schools every year. However, in 2020, because of the COVIT-19 pandemic, we
could not accept their visits.
There are many examples of publishing ordinary photos and introductory videos of facilities on the WEB.
However, there were only a few examples of publishing contents using virtual reality (VR), such as Materialand Life Science Experimental Facility (MLF) in JPARC [1]. We think that the important factor that enhances
the educational effect in facility tours is the sense of presence. When visiting large-scale research facilities
like synchrotron light sources, the realism of being able to experience their scales is a major attraction. The
VR technology that makes this possible will be widely used in the future. Fortunately, in recent years, theprice of VR viewing devices has fallen, and it is expected that their use will expand rapidly soon.
Under such a circumstance, we started developing a VR content of HiSOR, aiming to experience
producing VR contents and to seek the possible applications of the VR technologies in the accelerator
research and education. We prepared an omnidirectional (360 degree) camera [2] and a tripod. We took 360
degree photographs at many places in the experimental hall of HiSOR, which would be the standing pointof the audience in the VR facility tour. These photographs were combined into a VR content by using asoftware [3]. To determine the photograph spot, we were careful that one point could be seen from theneighboring ones (FIG. 1). Also, we were careful about keeping the height of the camera at about 170 cm
from the floor, which would give a natural feeling about the line of sight. By using the software, we put somepanels in the contents which explain the accelerators and the experimental apparatus. Also, we put a map at
the entrance of the experimental hall.
We found that the VR contents are not only a simple alternative of real site visiting. It is capable of giving
us a view which is normally impossible to see. For example, usually we cannot climb up the bending magnetsof the accelerator. However, it is easy to get a view from such a place by using a omnidirectional camera(FIG. 2). We found that this is very instructive to understand how the electron beam is circulating and how
the synchrotron radiation is extracted from the accelerator. In case of HiSOR, the visitors can see theaccelerators directly. However, normally, high energy accelerators are constructed in a tunnel. Therefore, thevisitors cannot see it directly even when they visited the facility. By using the VR technology, they canexperience the facility tour to see the inside of the tunnel even when the accelerator is in operation.
As a prospect, we think that developments towards augmented reality (AR) will be the next step, in which
the real pictures and computer graphics are mixed. In case of accelerator research and education, it isimportant to show what happens inside of the apparatus. It should be very instructive to understand theprinciple of accelerators and synchrotron light sources, if we could show how the electron beam is runningand how the synchrotron radiation is generated and extracted.

－9－

FIGURE 1. Camera positions in the facility along a route of the VR facility tour.

FIGURE 2. Ominidirectional Camera with tripod (left) and a view from the top of a bending magnet (right).

REFERENCES
1. https://mlfinfo.jp/ja/mlfvr.html.
2. https://theta360.com/ja/about/theta/s.html.
3. https://www.adobe.com/jp/products/captivate.html.

－ 10 －

Design Study on a Compact Storage Ring Light Sourcewith Superconducting Bending Magnets
Kai Hiramatsua, Miho Shimadac,a and M Katoha,baHiroshima University,1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan
Institute for Molecular Science, National Institutes of Natural Sciences, 38 Nishigo-Naka, Myodaiji,
Okazaki, 444-8585, Japanb
High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, 305-0801, Japanb

Keywords: Storage Ring, Superconducting Magnet.

HiSOR, the synchrotron light source in Hiroshima University, is compact and low energy. It has two
straight sections and is capable of producing high-intensity light in the vacuum ultraviolet region from two
undulators. Moreover, two bending magnets has high field strength of 2.7 T, although they are normal
conducting magnets. These magnets are capable of producing synchrotron radiation in a wide range
including tender X-rays even with the low electron energy of HiSOR, which is 700MeV. Since no major
modifications have been made since its construction, HiSOR is very stably operated in these years. On theother hand, after the 25 year operation since the construction, the hardware is being aged and its
competitiveness in terms of light source performance are being lowered among the newly constructed lightsources over the world. Some of the light sources in Japan, such as Photon Factory [1] or UVSOR [2], havebeen upgraded with some major modifications of hardware. SPring-8 also has an upgrade plan [3]. In caseof HiSOR, it was designed and manufactured by a single company. It has a rational design without
redundancy. This design concept makes it difficult to make a major modification to improve the performanceor introduce new technologies to the present machine. Therefore, we have been designing a completely new
ring for the future plan of the facility [4]. The design studies in the past have been focusing on achieving
higher brightness in the vacuum ultraviolet range by reducing the emittance. In this study, we haveinvestigated another direction, in which the wide spectral range up to the tender X-rays is achieved.
To produce X-rays at a low energy synchrotron light source, we have to utilize high field magnets. A
superconducting magnet is most favorable. However, it had been widely considered that the operation andthe maintenance of superconducting magnets are troublesome. The reason is that such devices are normallycooled by liquid helium and needs a helium refrigerator. However, in these years, in some synchrotron lightsources, superconducting magnets directly cooled by refrigerators without using liquid helium [5, 6].

FIGURE 1. Synchrotron radiation spectra from bending magnets. That of the present HiSOR is 700MeV-2.7T. That of the
new ring is 500MeV-5T (superconducting) and 500-1.38T (normal conducting).

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The typical field strength of such superconducting magnets is 5T. The synchrotron radiation spectra fromnormal and superconducting bending magnets are compared in FIG.1. It can be seen that the 5T
superconducting bending magnet in the 500MeV storage ring can cover almost similar spectral range as thebending magnets of the present HiSOR, whose electron energy is 700MeV.
Based on this result, we have designed a small racetrack-shaped ring consisting of two triple-bend cellswith 180 degree bending angle for each. The bending magnet in the center of the triple-bend cell is a hybrid
type that combines a superconducting and two normal conducting magnets. Here we assumed to use similar
superconduncting magnet which has been stably operated at Aichi synchrotron [6]. The electron energy is
reduced from the present value of 700MeV to 500MeV while ensuring the same wide bandwidth as thecurrent high field normal conducting magnets. This electron energy reduction may be beneficial to construct
the full energy injector for the future top-up operation. The ring has two long straight sections where two
undulators, a septum magnet for beam injection and the RF cavity will be installed. The layout of the ring isshown in FIG. 2. The circumference is about 28m and the emittance is about 80nm. The electron energy is
500MeV.

FIGURE 1. The layout of a compact storage ring with two superconducting bending magnets. The lattice consists of two
triple-bend cells. The bending magnet of the center of the cells is hybrid, which consists of a superconducting bending magnet
and two normal conducting bending magnets on both sides.

REFERENCES
1.
2.
3.
4.
5.
6.

M. Katoh et al., J. SYNCHROTRON RAD. 5(3) 366 - 368 (1998).
M. Katoh et al., Nucl. Instr. Meth. A. 467, 68 - 71 (2001).
http://rsc.riken.jp/pdf/SPring-8-II.pdf.
S. Matsuba et al., J. Phys. Conf. Ser. 1350 012015-1~5 (2019).
D. Robin et al., Nucl. Instr. Meth. A 538 (2005) 65.
Y. Takashima et al., Proc. IPAC2016, 2877-2879, (Busan, Korea, 2016).

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