ISSN 2186-7968

ELPH

ANNUAL REPORTTOHOKU UNIVERSITY

2018

Editor
MURAMATSU, Norihito
KIKUNAGA, Hidetoshi
ITOH, Takehiko
MUTO, Toshiya
TOKIYASU, Atsushi

Research Center for Electron Photon Science
Tohoku University
1-2-1 Mikamine, Taihaku, Sendai 982-0826
Japan

Phone: +81, 22-743-3400
Fax:+81, 22-743-3402

Web site: http://www.lns.tohoku.ac.jp/

982-0826

仙台市太白区三神峯1-2-1
東北大学電子光理学研究センター
電話022-743-3400

Fax

022-743-3402

Preface
We are pleased to issue the “ELPH Annual Report 2018” that covers scientific andtechnical activities carried out at Research Center for Electron Photon Science (ELPH),
Tohoku University in FY2018 (April, 2018 to March, 2019).
The ELPH has been in a second organization term of Joint Usage / ResearchCenters. The Joint Usage / Research Centers (JURC) system was engaged in FY2010 by
the Ministry of Education, Culture, Sports, Science and Technology (MEXT) to
encourage and promote collaborative research passing through the border of respective
universities. In FY2018, an interim evaluation for the first half term was performed.
The opinion insisting that the evaluation results should be reflected for budget
distribution has been so intense that they employed a relative evaluation for JURC. The
MEXT declared that 30 % of JURC would have budget reduction. This is not fully
acceptable for the most of JURC members. I do not want to criticize the system here,
fortunately ELPH succeeded to get some increased amount relying on strong supports
from users and communities.
However, we have still suffered shortage of budget, particularly the cost ofelectricity for the accelerator operation is crucial. In FY2018, we, nevertheless, got
loaned expense for replacing the RF power amp in the synchrotron for solid state onethat is reducing electricity power.
“The ELPH Symposium”, which is to explore the interest of basic science and post
the amount of scientific information for mutual collaboration between different
scientific fields, has been annually held since FY2017. In March 2019, the 2nd ELPH
symposium was carried out. This time we invited Prof. Tomoko Nakanishi of Universityof Tokyo, now the president of Hoshi University. She gave us a wonderful talkregarding radioisotope (RI) application for botanical science. Since RI production andits application is one of the major sciences in ELPH activity, we hope further
collaboration is being spread and developed.
We sincerely ask facility users and related scientific field communities forcontinuous supports and cooperation.
November, 2019
Director
Hiroyuki Hama

ELPH Annual Report 2018
Contents
I. Topics

A report on outreach activities at the Research Center for Electron Photon Science (ELPH)
Hiroaki Ohnishi

1

Overview of Condensed Matter Nuclear Reaction Division
Yasuhiro Iwamura

3

II. Papers

N Scattering Length from  Photoproduction on the Proton near the Threshold5
T. Ishikawa, H. Fujimura, H. Fukasawa, R. Hashimoto, Q. He, Y. Honda, A. Hosaka,
T. Iwata, S. Kaida, J. Kasagi, A. Kawano, S. Kuwasaki, K. Maeda, S. Masumoto,
M. Miyabe, F. Miyahara, K. Mochizuki, N. Muramatsu, A. Nakamura, S.X. Nakamura,
K. Nawa, S. Ogushi, Y. Okada, K. Okamura, Y. Onodera, K. Ozawa, Y. Sakamoto,
M. Sato, T. Sato, H. Shimizu, H. Sugai, K. Suzuki, Y. Tajima, S. Takahashi, Y. Taniguchi,
Y. Tsuchikawa, H. Yamazaki, R. Yamazaki, and H.Y. Yoshida
10
Study of dibaryons via d→00d at E = 0.75–1.15 GeV (II)T. Ishikawa, H. Fujimura, H. Fukasawa, R. Hashimoto, Q. He, Y. Honda, T. Iwata,
S. Kaida, H. Kanda, J. Kasagi, A. Kawano, S. Kuwasaki, K. Maeda, S. Masumoto,
M. Miyabe, F. Miyahara, K. Mochizuki, N. Muramatsu, A. Nakamura, K. Nawa,
S. Ogushi, Y. Okada, K. Okamura, Y. Onodera, K. Ozawa, Y. Sakamoto, M. Sato,
H. Shimizu, H. Sugai, K. Suzuki, Y. Tajima, S. Takahashi, Y. Taniguchi, Y. Tsuchikawa,
H. Yamazaki, R. Yamazaki, and H.Y. Yoshida
Current status of the FOREST/BLC experiments at ELPH
13
T. Ishikawa, K. Aoki, H. Fujioka, Y. Honda, T. Hotta, Y. Inoue, K. Itahashi, H. Kanda,
H. Kawai, K. Maeda, Y. Matsumura, M. Miyabe, S. Miyata, N. Muramatsu, T. Nishi,
H. Ohnishi, K. Ozawa, H. Shimizu, R. Shirai, M. Tabata, A.O. Tokiyasu, Y. Tsuchikawa,
H. Yamazaki, and C. Yoshida
Profile measurement of circulating electrons in a synchrotron using an internal radiator
18
Y. Obara, T. Ishikawa, H. Hama, F. Hinode, H. Kanda, S. Kashiwagi, M. Miyabe,
T. Muto, K. Ozawa, H. Shimizu, and A.O. Tokiyasu
The performance study of an electromagnetic calorimeter Foward Gamma
M. Miyabe, K. Kanomata, and GeV- group

22

Photo-production of a Neutral Kaon and/or a Lambda Hyperon on a deuteron near the threshold
25
Masashi Kaneta for the NKS2 collaboration
The performance test for the time resolution of Multi-gap Resistive Plate Chamber (one of theexperimental courses in Graduate Program on Physics for the Universe curriculum in Tohoku

University)
Masashi Kaneta, Toshiyuki Gogami, and Satoshi N. Nakamura

28

The performance test of the amplifier for Multi-gap Resistive Plate Chamber
Masashi Kaneta for the NKS2 collaboration

34

Development for the resistive plate chamber (RPC)
39
Yuto ISHIZUKI, Jumpei TAKAHASHI, Daisuke TAKI, Kento TERADA, andHiroaki Ohnishi
Performance evaluation of a scintillating fiber detector for the high-momentum secondary
beamline at J-PARC
44
T. Aramaki, T. Akaishi, H. Asano, C.-Y. Chang, W.-C. Chang, R. Honda, Y. Igarashi,
T. Ishikawa, S. Kajikawa, Y. Ma, K. Nagai, H. Noumi, H. Sako, K. Shirotori,
T.N. Takahashi, and for the J-PARC E50 collaboration
Development of a beam-timing detector for the charmed-baryon spectroscopy experiment at
J-PARC
58
T. Akaishi, T. Aramaki, H. Asano, C.-Y. Chang, W.-C. Chang, R. Honda, Y. Igarashi,
T. Ishikawa, S. Kajikawa, Y. Ma, K. Nagai, H. Noumi, A. Sakaguchi, H. Sako,
K. Shirotori, T.N. Takahashi, and for the J-PARC E50 collaboration
Test of Detectors and Trigger System for J-PARC E16 Experiment using Positron Beam
66
M. Naruki, S. Ashikaga, R. Fujii, M. Ichikawa, K.N. Suzuki, K. Aoki, K. Ozawa,
T.N. Murakami, T.N. Takahashi, and S. Yokkaichi
Performance Evaluation of a Fine-Grained Scintillator Tracker for the T2K Near Detector
Upgrade Project70
Konosuke Iwamoto, Ryo Fujita, Kohei Matsushita, Masashi Yokoyama,
Tsunayuki Matsubara, Soichito Kuribayashi, Tatsuya Kikawa, Takuji Arihara, andYuito Awataguchi
Evaluation of number of photon from small aerogel Cherenkov counter
Kazuki Okuyama and Masashi Kaneta for the NKS2 collaboration

77

New Drift Chamber for an electron spectrometer at SCRIT electron scattering facility
K. Tsukada, S. Takayama, and H. Wauke

81

Status of the LEPS2-solenoid experiment in 2018
Atsushi Tokiyasu for LEPS2 collaboration

85

Recent results of SPring-8 LEPS2/ BGOegg experiment
89
N. Muramatsu, T. Hashimoto, Y. Matsumura, M. Miyabe, T. Nam, H. Shimizu,
N. Tomida, J.K. Ahn, W.C. Chang, J.Y. Chen, S. Daté, T. Gogami, H. Hamano, Q.H. He,
K. Hicks, T. Hiraiwa, Y. Honda, T. Hotta, Y. Inoue, T. Ishikawa, I. Jaegle, J.M. Jo,
Y. Kasamatsu, H. Katsuragawa, S. Kido, Y. Kon, S. Masumoto, K. Miki, K. Mizutani,
T. Nakamura, T. Nakano, M. Niiyama, Y. Nozawa, Y. Ohashi, H. Ohkuma, H. Ohnishi,
T. Ohta, M. Oka, M. Okabe, K. Ozawa, C. Rangacharyulu, Y. Sada, M. Sasagawa,T. Shibukawa, R. Shirai, K. Shiraishi, E.A. Strokovsky, Y. Sugaya, M. Sumihama,
S. Suzuki, S. Tanaka, A. Tokiyasu, Y. Tsuchikawa, T. Ueda, H. Yamazaki, R. Yamazaki,

Y. Yanai, T. Yorita, C. Yoshida, and M. Yosoi
Production of a high energy  beam via inverse Compton scattering of soft x-rays from a short
undulator
97
Norihito Muramatsu, Masahiro Okabe, Shinsuke Suzuki, Schin Daté, Hajime Shimizu,
Haruo Ohkuma, Kazuhiro Kanda, Shuji Miyamoto, Tetsuo Harada, Takeo Watanabe,
Manabu Miyabe, and Atsushi Tokiyasu
Development of Multilayer Mirror for Producing a Next-generation Photon Beam
Masahiro Okabe, Norihito Muramatsu, and Isamu Ishikawa

102

Phantom production for a multiple-isotope -ray imaging system
T. Fukuchi, H. Haba, and H. Kikunaga

105

Application of Single Comparator Method to Instrumental Photon Activation Analysis
M. S. Reza, R. Taniguchi, J. Kaneko, and Y. Oura

107

Identification of Elemental Composition and Preparation of Radio-tracer for Recovery of Rare
Metals in Household Garbage Incineration Slag by Photon Activation Method 2112
K. Akiyama, K. Takano, H. Sugiyama, Ahmed S. A. Ali, K. Irfan, S. Kubuki, andH. Kikunaga
Development of simultaneous production method for carrier-free RI multitracer of potassium,rubidium and cesium
116
H. Ikeda, H. Kikunaga, and H. Watabe
Investigation of optimal thicknesses of W converters in electron linac production of 99Mo 120
Jaewoong Jang, Hidetoshi Kikunaga, Shun Sekimoto, Makoto Inagaki, Tomohiko
Kawakami, Tsutomu Ohtsuki, Shigeru Kashiwagi, Ken Takahashi, Kyo Tsukada, andMitsuru Uesaka

III. Status Report

Status of Accelerator Facilities in FY2018
129
F. Hinode, K. Kanomata, S. Kashiwagi, S. Miura, T. Muto, I. Nagasawa, K. Nanbu,
Y. Shibasaki, K. Takahashi, H. Hama
User Support Office Report in FY2018
M. Miyabe and User Support Office

134

Radiation Safety Report 2018
Radiation Safety Office137

IV. List of Publication

139

V. Members of Committees

153

VI. Approved Experiments

157

I. Topics

ELPH Annual Report, Tohoku University (2018)1

A report on outreach activities at the Research Center forElectron Photon Science (ELPH)
Hiroaki Ohnishi∗§ 1. Introduction

The introduction of our scientific research projects and educational activities for science to the public

is one of the important responsibilities imposed on the Joint Usage/Research center, such as the research
center of ELectron Photon Science (ELPH ). For that purpose, we have conducted an open campus event
every other year to invite people including elementary, junior high school and high school students living
near our facility. Moreover, we are constantly inviting high school students to try to get an understandingof the science that is being explored at ELPH using accelerators.
In this report, a digest of the open campus in 2018, and a summary of the facility tour event ofstudents from Miyagi first senior High School will be introduced.

§ 2. Open Campus 2018

On April 14th, the ELPH Open Campus was held at the Mikamine

campus of Tohoku University, where ELPH is located. Open Campus
consisted of (1) ELPH facility tour, (2) experience conner and (3) General lecture by Prof. T. Suda entitled ”Story on Elements - From theLightest Hydrogen to the Super Heavy Element, i.e., Nihonium” In total, about two hundred people were coming to the events. We explained
science projects we are conducting at the ELPH facility in front of theaccelerator and experimental apparatus. Moreover, many participants,
especially children, enjoyed the experience conner such as demonstration of a cloud chamber, production of hand made a simple light spectrometer, play with a magnet and gyroscope. Snapshot of the facility
tour and experience conner was shown in Fig. 1§ 3. Facility tour of Miyagi First Senior High school students

On October 17th in 2019, about eighty students visited ELPH as part of their science education.

Prof. H. Ohnishi made a general lecture for an overview of the nuclear hadron physics and AssociateProf. H. Kikunaga did a lecture about introduction to radiochemistry. After the lecture, students visitedthe accelerator facility and experimental areas. Due to the passionate explanations by staff members
and active discussions with students, the facility tour has ended well exceeded the allocated time slot.

∗

Present address: Research Center for Electron Photon Science, Tohoku University, Sendai, 982-0826

2

Fig.1.

Snap shot of the facility tour and experience connerFig.2.

Snap shot of the lecture and facility tour.

§ 4. Future prospectives

The next open campus is now planning in the spring of 2020. To invite more people, we need to

explore efficient ways of advisement for the event. In addition, it may also be important to make aclosed connection between the public relations section on the Faculty of Science at Tohoku University
and ELPH. Moreover, we also need to find a way how can we reach the local community more closely. it
will be excellent if we succeed to make a joint project with the local community as an outreach project
for ELPH. The door on the ELPH is always open for the public, we need to continue to take actions to
outside to enlighten science. It is one of the missions for us, ELPH.

ELPH Annual Report, Tohoku University (2018)3

Overview of Condensed Matter
Nuclear Reaction Division
Yasuhiro Iwamura

Research Center for Electron Photon Science, Tohoku University, Sendai, 982-0826

Global warming has become an undisputed fact and an energy source that does notproduce greenhouse gases such as carbon dioxide is more and more strongly demanded.
Because of this, renewable energy use has increased worldwide, but the renewable energy has
low energy density and the output energy fluctuates depending on weather conditions. On theother hand, nuclear energy has high energy density but has serious problems such asradioactive waste and the Fukushima disaster. It is expected that nuclear energy will notincrease, because society opposes it.
The anomalous heat generation phenomenon, which cannot be explained by any known
chemical process, has been reported in experimental systems that consist of nano-sized metalcomposite and hydrogen gas [1-5]. This phenomenon is recognized as one in a category ofCondensed Matter Nuclear Reaction (CMNR). Strong and hazardous gamma-rays or neutrons,
which effect the human body, have not been observed during the generation of anomalous heat.
This phenomenon has potential for realization of a new safe and compact energy source thatwould provide us HQRXJK energy to meet all our needs without carbon dioxide emissions.
The Condensed Matter Nuclear Reaction Division of Research Center for Electron
Photon Science at Tohoku University has started since April. 2015. It is the first official
research division created for condensed matter nuclear reaction (CMNR) and its application in
Japan. The organization of the division is illustrated in Fig.1. Y. Iwamura and T. Itoh were

investigating nuclear transmutation reactions observed in the nano-sized Pd complexes induced by
D2 gas permeation [6-8] and left Mitsubishi Heavy Industries, ltd. to join the division. Y. Iwamura
is a research professor of Tohoku University and T. Itoh is a visiting associate professor. Itoh isalso a director of Clean Planet Inc. J. Kasagi is a professor emeritus and has been investigating
the electronic and ionic screening effects on low-energy nuclear reactions in condensed matter as
described in the former section. H. Kikunaga is an associate professor and has been engaged in thefield of radiochemistry. H. Yoshino is a visiting researcher in this division and a CEO of Clean
Planet Inc.
Collaborative researchwith Clean Planet Inc. has
been mainly performed and
NEDO project research withTechnova Inc., Nissan Motor
Co. Ltd., Kobe Univ., Kyushu
Univ. and Nagoya Univ. wasdone from 2015 to 2017 inadditiontocollaborative
research
with
MHI
on
permeation-induced
transmutation.

4

Figure 2 shows the summary of experimental results on generated energy per fuel(hydrogen or deuterium) in our division from 2015 to 2018. Several experimental methods were tried,
however, the combination of Ni based multilayer thin films and hydrogen gas demonstrated the best results.
Anomalous heat generation was supposed to be induced during hydrogen diffusion process by heating up the metal
multilayer thin film that absorbed hydrogen gas before heating. Generated excess energy ranged from 1
MJ/g to 1 GJ/g as shown in Fig.2. The 1 GJ/g corresponded to about 10 keV/H, which is too muchto be explained by any known chemical process.
We will continue to investigate what is happening in the nano-sized multilayer metalcomposite and would like to obtain experimental key factors to control Condensed Matter Nuclear
Reactions.

Acknowledgment
The author deeply thanks Mr. T. Itoh (Tohoku U. and CLEAN PLANET Inc.), Mr. S. Murakami
and Dr. M. Saito (CLEAN PLANET Inc.) for their considerable contribution for this work. The
author also express appreciation to Prof. J. Kasagi (Tohoku U.) and Prof. H. Kikunaga (Tohoku U.)
for valuable discussions. We also acknowledge Mr. H. Yoshino, Mr. S. Hirano, Mr. M. Ise and Mr.
M. Hattori, who are the members of CLEAN PLANET Inc., for their significant assistance. This
work is supported by CLEAN PLANET Inc., Thermal & Electric Energy Technology Foundation(TEET), Tanaka Kikinzoku Memorial Foundation and Research Center for Electron Photon Scieceof Tohoku University.

References
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]

A. Kitamura et al.: International Journal of Hydrogen Energy 43 (2018) 16187.
T. Itoh et al.: J. Condensed Matter Nucl. Sci. 24 (2017) 179.
Y. Iwamura et al.: J. Condensed Matter Nucl. Sci. 29 (2019) 119.
Y. Iwamura et al.: J. Condensed Matter Nucl. Sci. 24 (2017) 191.
Y. Iwamura et al.: Cold Fusion; Advances in Condensed Matter Nuclear Science, ed. by J.
Biberian, Elsevier, Amsterdam, to be published on Jan.01, 2020.
Y. Iwamura, M. Sakano and T. Itoh, Jpn. J. Appl. Phys. 41 (2002) 4642-4648.
Y. Iwamura, T. Itoh and S. Tsuruga, Current Science, Vol.108, No.4, (2015) 628-632.
Y. Iwamura, T. Itoh, et.al, Fusion Technology, 33 (1998) 476-492.

II. Papers

ELPH Annual Report, Tohoku University (2018)

5(ELPH Experiment : #2623, #2640, #2655, #2694, #2710)

ωN Scattering Length from ω Photoproduction on the
Proton near the Threshold
T. Ishikawa1 , H. Fujimura1∗ , H. Fukasawa1 , R. Hashimoto1† , Q. He1‡ ,Y. Honda1 , A. Hosaka2,3 , T. Iwata4 , S. Kaida1 , J. Kasagi1 , A. Kawano6 ,S. Kuwasaki1 , K. Maeda5 , S. Masumoto7 , M. Miyabe1 , F. Miyahara1§ ,K. Mochizuki1 , N. Muramatsu1 , A. Nakamura1 , S.X. Nakamura8 , K. Nawa1 ,S. Ogushi1 , Y. Okada1 , K. Okamura1 , Y. Onodera1 , K. Ozawa9 , Y. Sakamoto6 ,M. Sato1 , T. Sato2 , H. Shimizu1 , H. Sugai1¶ , K. Suzuki1∥ , Y. Tajima4 ,S. Takahashi1 , Y. Taniguchi1 , Y. Tsuchikawa1∗∗ , H. Yamazaki1†† ,R. Yamazaki1 , and H.Y. Yoshida41

Research Center for Electron Photon Science (ELPH), Tohoku University, Sendai 982-0826,
Japan
2

3

Research Center for Nuclear Physics, Osaka University, Ibaraki 567-0047, Japan.

Advanced Science Research Center, Japan Atomic Energy Agency (JAEA), Tokai 319-1195,Japan
4

Department of Physics, Yamagata University, Yamagata 990-8560, Japan
5

6

Department of Physics, Tohoku University, Sendai 980-8578, Japan

Department of Information Science, Tohoku Gakuin University, Sendai 981-3193, Japan
7
8

9

Department of Physics, University of Tokyo, Tokyo 113-0033, Japan

University of Science and Technology of China, Hefei 230026, China

Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization(KEK), Tsukuba 305-0801, Japan

We have measured the total cross section as a function of the incident energy ranging from 1.08
to 1.15 GeV. The 1/2 and 3/2 spin-averaged scattering length aωN and effective range rωN between∗

Present address: Department of Physics, Wakayama Medical University, Wakayama 641-8509, Japan†

Present address: Institute of Materials Structure Science (IMSS), High Energy Accelerator Research
Organization (KEK), Tsukuba 305-0801, Japan‡

Present address: Department of Nuclear Science and Engineering, Nanjing University of Aeronautics
and Astronautics (NUAA), Nanjing 210016, China§

Present address: Accelerator Laboratory, High Energy Accelerator Research Organization (KEK),
Tsukuba 305-0801, Japan¶

Present address: Gunma University Initiative for Advanced Research (GIAR), Maebashi 371-8511,
Japan

∥

Present address: The Wakasa Wan Energy Research Center, Tsuruga 914-0192, Japan∗∗

Present address: aterials and Life Science Division, J-PARC Center, Japan Atomic Energy Agency(JAEA), Tokai 319-1195, Japan††

Present address: Radiation Science Center, High Energy Accelerator Research Organization (KEK),
Tokai 319-1195, Japan6the ω meson and nucleon are extracted from the excitation function of the total cross section using amodel with the final-state ωN interaction based on the Lippmann-Schwinger scattering equation. The
)
(
)
)
(
)
(
(
+0.15
+0.68
+0.46
obtained values are aωp = −0.97+0.16−0.16 + i 0.07−0.14 fm and rωp = +2.78−0.54 + i −0.01−0.50 fm,
suggesting a strong repulsive force. The details are described in a preprint [T. Ishikawa et al., arXiv:
1904.02797 (2019)].

§ 1. Introduction

The structure of hadrons and dynamical hadron-mass generation are the most important subjects

to be studied in the non-perturbative domain of quantum chromodynamics (QCD). Investigation of theproperties of hadrons will provide a clear picture for unraveling the dynamics of their internal structure.
The ω meson (ω) is one of the best established hadrons, and it is considered to give a short-ranged
repulsive central force and a strong spin-orbit force between two nucleons (N s) [1]. Nevertheless, thefundamental properties of ω such as the interaction with N is not known yet due to the difficulties inrealizing scattering experiments because of the neutral and unstable nature of ω. Detailed informationon ωN scattering would not only reveal highly excited nucleon resonances (N ∗ ) but also have a strong
relevance to the equation of state describing the interior of neutron stars [2].
The low-energy ωN scattering is characterized by the scattering length aωN and effective rangerωN . These parameters are obtained from an effective-range expansion of the S-wave phase shift δ(p)with the ω momentum p in the ωN center-of-mass (CM) frame as defined in the following equation:p cot δ(p) =1
1rωN p2 + . . . .
+
aωN
2

(1)

A positive (negative) Re aωN gives attraction (repulsion) in this definition. Recently, the A2 collaboration
at the Mainz MAMI facility has reported |aωN | = 0.82 ± 0.03 fm, which is extracted from ω photoproduc-tion on the proton (γp → ωp) near the threshold assuming a vector meson dominance (VMD) model [3].
The unknown sign of aωN leaves a naive question of whether low-energy ωN scattering is repulsive or
attractive.
To determine the low-energy ωN scattering parameters aωN and rωN , we measured the total crosssections for the γp → ωp reaction very close to the reaction threshold where the S-wave ωN contribution
is dominant. We have determined the aωN and rωN values from the shape of the total cross section

as a function of the incident energy (excitation function) through ωN rescattering in the final-stateinteraction.

§ 2. Total Cross section

We have measured the total cross section for the γp → ωp reaction at Eγ < 1.15 GeV [6] using

the FOREST detector [5]. The ω mesons are identified in the ω → π 0 γ decay mode. All the data forincident energies above 1.08 GeV are divided into ten bins so that every bin includes four photon-tagging
channels. The data are also divided into ten bins for the π 0 γ emission angle cos θ in the γp-CM frame.
Each π 0 γ invariant-mass (Mπγ ) distribution shows a prominent peak with a centroid of ∼ 0.78 GeV, andhas a broad background contribution in the lower side. This background contribution is well reproduced

7by a Monte-Carlo (MC) simulation based on Geant4 [8] for the γp → π 0 π 0 p → γγγγp reaction [9], where
one γ out of four is not detected with FOREST. The number of the ω produced events is estimated after

subtracting the background γp → π 0 π 0 p contribution for each bin, and the angular differential crosssection is obtained. Fig. 2 in Ref. [10] shows the typical angular differential cross section. The total

cross section σ is obtained by integrating dσ/dΩs all over the ten emission-angle bins. Fig. 3 in Ref. [10]shows σ as a function the incident photon energy Eγ .

§ 3. Scattering parameters

We determine aωp and rωp from the shape of the excitation function. We evaluate the excitation

function for the γp → ωp reaction using a model with final-state ωp interaction (FSI) based on the
Lippmann-Schwinger equation. We assume that the S-wave contribution is dominant at Eγ = 1.08–

1.15 GeV. The total cross section for a fixed ω mass M and γp-CM energy W can be calculated using atransition amplitude Tγp→ωp (W, M ):σ0 (W, M ) =p(W, M )1
2|Tγp→ωp (W, M )| ,16πW 2k(2)where k and p denote the momenta of an initial- and a final-state particles, respectively, in the γpCM frame. The total cross section σ as a function of Eγ is obtained by averaging σ0 (W (Eγ ), M ) overavailable ω masses:∫ W (Eγ )−mp
σ0 (W (Eγ ), M )Lω (M )dM,
σ(Eγ ) =

(3)

mπ 0

where the probability Lω (M ) stands for a Breit-Wigner function with a centroid of Mω = 782.65 MeV
and a width of Γω = 8.49 MeV [4]. The Tγp→ωp is expressed by
Tγp→ωp = Vγp→ωp + Tωp→ωp Gωp→ωp Vγp→ωp ,(4)where Tωp→ωp stands for the ωp scattering amplitude, Gωp→ωp denotes the ωp propagator, and Vγp→ωp
is the production amplitude without FSI. We evaluate the matrix element for Tγp→ωp with on-shell
approximations for Tωp→ωp and Vγp→ωp , and introduce a Gaussian form factor in the integration ofGωp→ωp . The equation for the matrix element of Tγp→ωp is given in Ref. [10].
The excitation function with aωp = 0 fm and rωp = 0 fm corresponding to non FSI condition,
which does not reproduce the experimental data. FSI is necessary and the optimal set of aωp and rωp
are determined to reproduce the experimentally-obtained cross-section data. The deduced parameters
)
(
)
)
(
)
(
(
+0.15
+0.68
+0.46
+
i
0.07
fm
and
r
+
i
−0.01
=
+2.78
are aωp = −0.97+0.16
ωp
−0.16
−0.14
−0.54
−0.50 fm. The detailed

discussion to deduce the scattering parameters are described in Ref. [10] including uncertainties fromthe Gaussian form factor in the ωp propagator, the P -wave contribution, the energy dependence ofVγp→ωp , and mis-calibration of incident energies.
The obtained aωp is consistent with |aωp | = 0.82 ± 0.03 fm given by the A2 collaboration [3]. A

positive Re aωp value giving, an attraction, is rejected at a confidence level higher than 99.9%. No boundor virtual state is expected in the ωN channel from the strong repulsion results. Slightly attractive ωnucleus (ωA) interactions are reported with potential depths at normal nuclear density of −42 ± 17 ± 20

8MeV [11] and −15 ± 35 ± 20 MeV [12] from ω photoproduction from nuclei. The measurement of ωline shape shows a decrease of ω mass by 9.2% ± 0.2% (corresponding to ωA attraction) without any
in-medium broadening [13, 14]. The relation between strong ωN repulsion and ωA attraction would

be a subject of future discussions taking into consideration spin-dependent terms, higher partial waves,and partial restoration of chiral symmetry.

§ 4. Summary

The total cross sections have been measured for the γp → ωp reaction near the threshold. The ω is

identified through the ω → π 0 γ decay. The spin-averaged scattering length aωp and effective range rωp

between the ω and proton are estimated from the excitation function at incident photon energies ranging
)
)
)
(
)
(
(
(
+0.68
+0.46
+0.15
from 1.08 to 1.15 GeV: aωp = −0.97+0.16−0.16 + i 0.07−0.14 fm and rωp = +2.78−0.54 + i −0.01−0.50

fm. The real and imaginary parts for aωp and rωp are determined separately for the first time. A small
P -wave contribution does not affect the obtained values. The positive Re aωp value indicates repulsion.

The detailed discussions including comparison between previous experiments, and estimation of thesystematic uncertainties are described in a preprint [T. Ishikawa et al., arXiv: 1904.02797 (2019)].

Acknowledgments
The authors express their gratitude to the ELPH accelerator staff for stable operation of the accelerators in the FOREST experiments. They also acknowledge Mr. K. Matsuda, Mr. K. Nanbu, and
Mr. I. Nagasawa for their technical support. This work was supported in part by the Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT) and Japan Society for the Promotionof Science (JSPS) through Grants-in-Aid for Specially Promoted Research No. 19002003, for Scientific
Research (A) Nos. 24244022 and 16H02188, for Scientific Research (B) Nos. 17340063 and 19H01902,
for Scientific Research (C) No. 26400287, and for Scientific Research on Innovative Areas Nos. 18H05407
and 19H05141.

References[1]

R. Machleidt: Adv. Nucl. Phys. 19, 189 (1989).

[2]

H. Shen, H. Toki, K. Oyamatsu, K. Sumiyoshi: Nucl. Phys. A 637, 435 (1998).

[3]

I.I. Strakovsky et al. (A2 collaboration at MAMI): Phys. Rev. C 91, 045207 (2015).

[4]

M. Tanabashi et al. (Particle Data Group): Phys. Rev. D 98, 030001 (2018).

[5]

T. Ishikawa et al.: Nucl. Instrum. Meth. A 832, 108 (2016).

[6]

T. Ishikawa et al.: Nucl. Instrum. Meth. A 622, 1 (2010);
T. Ishikawa et al.: Nucl. Instrum. Meth. A 811, 124 (2016);
Y. Matsumura et al.: Nucl. Instrum. Meth. A 902, 103 (2018);
Y. Obara et al.: Nucl. Instrum. Meth. A 922, 108 (2019).

[7]

T. Ishikawa et al.: Phys. Lett. B 772, 398 (2017); Phys. Lett. B 789, 413 (2019).

9[8]

S. Agostinelli et al.: Nucl. Instrum. Meth. A 506, 250 (2003);
J. Allison et al.: IEEE Trans. Nucl. Sci. 53, 270 (2006);
see http://geant4.cern.ch/.

[9]

A. Fix, H. Arenhövel: Euro. Phys. J. A 25, 115 (2005);
The 2-PION-MAID calculations are available at http://maid.kph.uni-mainz.de/twopion/.

[10] T. Ishikawa et al.: arXiv: 1904.02797 (2019).
[11] V. Metag et al.: Prog. Part. Nucl. Phys. 67, 530 (2012); Hyperfine Interact. bf 234, 25 (2015).
[12] S. Friedrich et al. (CBELSA/TAPS collaboration): Phys. Lett. B 736, 26 (2014).
[13] K. Ozawa et al.: Phys. Rev. Lett. 86, 5019 (2001).
[14] M. Naruki et al.: Phys. Rev. Lett. 96, 092301 (2006).

10

ELPH Annual Report, Tohoku University (2018)(ELPH Experiment : #2623, #2640, #2655, #2694, #2710)

Study of dibaryons via γd → π 0π 0d at Eγ = 0.75–1.15 GeV(II)
T. Ishikawa1 , H. Fujimura1∗ , H. Fukasawa1 , R. Hashimoto1† , Q. He1‡ ,Y. Honda1 , T. Iwata2 , S. Kaida1 , H. Kanda3§ , J. Kasagi1 , A. Kawano4 ,S. Kuwasaki1 , K. Maeda3 , S. Masumoto5 , M. Miyabe1 , F. Miyahara1¶ ,K. Mochizuki1 , N. Muramatsu1 , A. Nakamura1 , K. Nawa1 , S. Ogushi1 ,Y. Okada1 , K. Okamura1 , Y. Onodera1 , K. Ozawa6 , Y. Sakamoto4 , M. Sato1 ,H. Shimizu1 , H. Sugai1∥ , K. Suzuki1∗∗ , Y. Tajima2 , S. Takahashi1 ,Y. Taniguchi1 , Y. Tsuchikawa1†† , H. Yamazaki1‡‡ , R. Yamazaki1 ,and H.Y. Yoshida2
1

Research Center for Electron Photon Science (ELPH), Tohoku University, Sendai 982-0826,
Japan
2

Department of Physics, Yamagata University, Yamagata 990-8560, Japan
3

4

Department of Physics, Tohoku University, Sendai 980-8578, Japan

Department of Information Science, Tohoku Gakuin University, Sendai 981-3193, Japan
5

6

Department of Physics, University of Tokyo, Tokyo 113-0033, Japan

Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization(KEK), Tsukuba 305-0801, JapanThe total and differential cross sections were measured for the γd → π 0 π 0 d reaction at incident

energies ranging from 0.75 to 1.15 GeV by using the FOREST detector at ELPH: the excitation functionof the total cross section, angular distributions of d and π 0 s, invariant-mass distributions for π 0 d andπ 0 π 0 . The present work suggests a sequential process γd → RIS → π 0 RIV → π 0 π 0 d is dominant with∗Present address: Department of Physics, Wakayama Medical University, Wakayama 641-8509, Japan†

Present address: Institute of Materials Structure Science (IMSS), High Energy Accelerator Research
Organization (KEK), Tsukuba 305-0801, Japan‡

Present address: Department of Nuclear Science and Engineering, Nanjing University of Aeronautics
and Astronautics (NUAA), Nanjing 210016, China§

Research Center for Nuclear Physics (RCNP), Osaka University, Ibaraki 567-0047, Japan¶

Present address: Accelerator Laboratory, High Energy Accelerator Research Organization (KEK),
Tsukuba 305-0801, Japan∥

Present address: Gunma University Initiative for Advanced Research (GIAR), Maebashi 371-8511,
Japan

∗∗

Present address: The Wakasa Wan Energy Research Center, Tsuruga 914-0192, Japan††

Present address: aterials and Life Science Division, J-PARC Center, Japan Atomic Energy Agency(JAEA), Tokai 319-1195, Japan‡‡

Present address: Radiation Science Center, High Energy Accelerator Research Organization (KEK),
Tokai 319-1195, Japan11
two 2.47- and 2.63-GeV isoscalar dibaryons (RIS ) and a 2.14-GeV isovector dibaryon (RIV ). This issue
has been already reported in the previous annual report. We discuss a modification in determining themass and width of RIV in the π 0 d invariant-mass distributions. The details are described in a publishedpaper [Phys. Lett. B 789, 413 (2019)].

§ 1. Mass and width of RIV

The mass and width are determined by fitting a function, expressed as a sum of a Breit-Wigner(BW) peak, its reflection, and phase-space contributions, to the π 0 d invariant-mass (Mπd ) data. In theprevious report, a BW peak and its reflection were summed up at a cross-section level. The function wasgiven by convolution of a Gaussian with an experimental mass resolution of σM = 0.011 GeV, and∫{α (LM,Γ (m1 ) + LM,Γ (m2 )) + C} VPS (m1 , m2 ) dm2 ,(1)
N (m1 ) =m2

where LM,Γ (m) represents the BW function with M and Γ, and VPS (m1 , m2 ) expresses the phase-spacecontribution. The acceptance was taken into account depending on Mππ , Mπd , and cos θd to estimate

VPS (m1 , m2 ). The parameters obtained were M = 2.15±0.01 GeV and Γ=0.11±0.01 GeV. The mass isslightly lower than the sum of the N and ∆ masses (∼2.170 GeV), and the width is narrower than thatof ∆ (∼0.117 GeV) [1].
Since the produced two π 0 s are identical, we have changed a way to sum up BW-peaks at an amplitude level. The function is given by convolution of a Gaussian with an experimental mass resolution ofσM = 0.011 GeV, and
∫ (
)
�
�2
L
�
α �AL
(m
)
+
A
(m
)
+
C
VPS (m1 , m2 ) dm2 ,N (m1 ) =
1
2
M,Γ
M,Γ

(2)

m2

( 2
)−1
2
represents the BW amplitude with M and Γ. The parameters
where ALM,Γ (m) = m − M + iM Γ

obtained are M = 2.14±0.01 GeV and Γ=0.09±0.01 GeV. The mass becomes slightly lower, and thewidth becomes narrower.

§ 2. Summary

The total and differential cross sections have been measured for the γd→π 0 π 0 d reaction at incident

energies from 0.75 to 1.15 GeV. A sequential process γd → RIS → π 0 RIV → π 0 π 0 d is found to be

dominant with 2.47- and 2.63-GeV RIS and 2.14-GeV RIV . The way has been modified to determine themass and width of RIV in the π 0 d invariant-mass distributions. The mass becomes slightly lower, andthe width becomes narrower. The details including figures can be found in a published paper [Phys. Lett.
B 789, 413 (2019)].

Acknowledgments
The authors express their gratitude to the ELPH accelerator staff for stable operation of the accelerators in the FOREST experiments. They also acknowledge Mr. K. Matsuda, Mr. K. Nanbu, and
Mr. I. Nagasawa for their technical support. This work was supported in part by the Ministry of Education, Culture, Sports, Science and Technology, Japan through Grants-in-Aid for Scientific Research (B)12No. 17340063, for Specially Promoted Research No. 19002003, for Scientific Research (A) No. 24244022,
for Scientific Research (C) No. 26400287, and for Scientific Research (A) No. 16H02188.

References[1]

C. Patrignani et al. (Particle Data Group): Chin. Phys. C 40, 100001 (2016).

13

ELPH Annual Report, Tohoku University (2018)(ELPH Experiment : #2803, #2844, #2882, #2894)

Current status of the FOREST/BLC experiments at ELPH
T. Ishikawa1 , K. Aoki2 , H. Fujioka3 , Y. Honda1 , T. Hotta4 , Y. Inoue1 ,K. Itahashi5 , H. Kanda4 , H. Kawai6 , K. Maeda7 , Y. Matsumura1 , M. Miyabe1 ,S. Miyata8 , N. Muramatsu1 , T. Nishi5 , H. Ohnishi1 , K. Ozawa2 , H. Shimizu1 ,R. Shirai1 , M. Tabata6 , A.O. Tokiyasu1 , Y. Tsuchikawa9 , H. Yamazaki1 ,and C. Yoshida1
1Research Center for Electron Photon Science (ELPH), Tohoku University, Sendai 982-0826,
Japan

2

Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization(KEK), Tsukuba 305-0801, Japan
3

4

Department of Physics, Tokyo Institute of Technology, Tokyo 152-8551, Japan

Research Center for Nuclear Physics (RCNP), Osaka University, Ibaraki 567-0047, Japan
5

Nishina Center for Accelerator-Based Science, RIKEN, Wako 351-0198, Japan
6
7

Department of Physics, Tohoku University, Sendai 980-8578, Japan

8
9

Department of Physics, Chiba University, Chiba 263-8522, Japan

Department of Physics, University of Tokyo, Tokyo 113-0033, Japan

Department of Physics, Nagoya University, Nagoya 464-8602, JapanThe FOREST/BLC experiments are conducted primarily aiming to determine low-energy S-wave
ηn scattering parameters using the γd → pηn reaction with a special kinematics. The photon beamwith energies around 940 MeV can give the recoilless condition of produced η mesons by detecting theprotons at 0◦ . The effects of the final-state ηn interaction must be enhanced due to the small relative
momentum between the η meson and the residual neutron in this kinematics. In this year, the physics
data were collected from June 6 to June 25 and October 12 to November 4 in 2018. In this report, a briefsummary of the current status of the FOREST/BLC experiments and collected data are described.

§ 1. Introduction

The nucleon resonance N (1535)S11 (N ∗ ) is an interesting object, which can be an S-wave ηNmolecule-like state and/or the chiral partner of the nucleon N . Whether N ∗ is composite or elementary
can be given by the scattering length aηN and effective range rηN in an effective-range expansion of the
S-wave phase shift:k cot δ(k) =

1
aηN

+

1
rηN k2 + O(k4 )2(1)through the pole position of N ∗ [1]. The aηN values have been extracted by many theoretical analyses
from the differential and total cross sections for the πN → πN , πN → ηN , γN → πN , and γN → ηNreactions. Although the imaginary part of aηN (Im[aηN ]) concentrates ∼ 0.26 fm for different analyses,

its real part (Re[aηN ]) scatters in a wide range from 0.2 to 1.1 fm [2]. This uncertainty comes from the14fact that the existing experimental data do not include the ηN -scattering amplitude directly. We proposethe γd → ηpn reaction to determine aηN at a certain kinematics, which enhances the ηN scattering

effect.

The incident photon bombards the quasi-free proton in the deuteron and produces a virtual η mesonwith a very low momentum. Events are selected in which the incident energy is approximately 0.94 GeV
and the proton is detected at 0◦ . The kinematics for these events satisfies the recoilless condition of the
produced η mesons. Thus, low-energy ηn scattering is expected to take place in this condition, where
the pn and ηp rescattering effects are suppressed owing to their large relative momenta (∼ 0.94 GeV).
The sensitivity to the Re[aηn ] and Re[rηn ] values are investigated and summarized in Ref. [3] by usinga model based on a dynamical coupled-channel meson-baryon scattering analysis [4, 5].

§ 2. Experimental setup

The γd → pηn reaction is measured at ELPH with the FOREST electromagnetic calorimeter sys-

tem [6] together with an additional forward charged-particle spectrometer called BLC [7]. The incident

photon energy ranges from 0.82 to 1.26 GeV [9] for the circulating energy of 1.32 GeV in the electron
synchrotron called the booster storage (BST) ring [10]. The details of the FOREST detector including
the liquid deuterium target are described elsewhere [8]. The forward scattered proton is momentumanalyzed with the BLC spectrometer behind FOREST. The trajectory of a charged particle is measured
with 2 planar drift chambers (DCs), and the time of flight is measured with 14 plastic scintillator (PS)hodoscopes (PSH+). An additional e/π separation is made using 10 SF5 lead-glass Cherenkov counters(LGCs). The experimental setup has been fixed since November in 2017. In this year, the physics data
were collected in the two periods: June 6 to June 25 (2018A) and October 12 to November 4 (2018B) in
2018.
The BLC magnet was excited every time at normal operation in this fiscal year with a coil currentof 1400 A. The magnetic flux By at the center was monitored with a nuclear magnetic resonance (NMR)
probe during the experiments, and By = 716.0 mT was adjusted by changing the coil current. Fig. 1
shows the magnetic flux By at the center for the 2018A and 2018B periods.

§ 3. Collected data

The physics data with the deuterium and hydrogen targets were collected both in the 2018A and2018B periods. The BST ring was operated with a circulating energy of 1.32 GeV, a current of approximately 20 mA, and an RF frequency of 500.14 MHz. It should be noted that the frequency was 500.18
MHz before the 2011 earthquake. The data collections were basically stable both in the periods. A sudden huge earthquake at 3:36am on October 26 in 2018, however, made the pedestal width broader in the
Be203 channel. This problem was fixed 11:40pm on October 29 in 2018. Table 1 summarizes the numberof spills and events of the collected data in this fiscal year (2018). The statistics for the hydrogen data issimilar to that for the 2009D period, and that for the deuterium data is 1.5 times higher. The data analysis is on-going to perform the precise energy and timing calibrations of the STB-Tagger II, FOREST,

716.2716.1
B (mT)

B (mT)

716.1

716

716

715.9

715.9

715.8

715.8

715.7

Oct 12
Oct 13
Oct 14
Oct 15
Oct 16
Oct 17
Oct 18
Oct 19Oct 20
Oct 21
Oct 22
Oct 23
Oct 24
Oct 25
Oct 26
Oct 27
Oct 28
Oct 29Oct 30
Oct 31
Nov 01
Nov 02
Nov 03
Nov 04

Jun 25

Jun 24

Jun 23

Jun 22Jun 21

Jun 20Jun 19Jun 18Jun 17

Jun 16

Jun 15

Jun 14

Jun 13

Jun 12

Jun 11

Jun 10

Jun 09Jun 08716.2

Jun 07

15

0

2

4

6

8
10
time (day)

12

14

16

18

715.7

0

2.5

5

7.5

10

12.5
time (day)

15

17.5

20

22.5

Fig.1. Magnetic flux By at the center for the 2018A (left) and 2018B (right) periods measured
with an NMR probe. The horizontal solid lines correspond to the magnetic flux values increased by ±0.001%, ±0.01%, ±0.02% from the central value 716.00 mT. The red verticalline in 2018A corresponds to the starting time to excite the magnet at normal operation.
The red vertical lines in 2018B correspond to the starting times to collect the hydrogen,empty, and deuterium targets, and the magenta lines express a huge earthquake, andfixing the Be203 pedestal trouble from the earthquake.
and BLC detectors. Additionally, the physics analysis has just started using the acquired data as shownin section 4.
Table 1. Numbers of spills and events collected in this fiscal year (2018). The circulating electronenergy of the BST ring was 1.32 GeV. The targets used were liquid hydrogen, deuterium,and empty.
period
2018A
2018B

hydrogen#spills#events
36.39 k 467.60 M
49.48 k 747.72 M

deuterium#spills#events
36.64 k 492.38 M
47.34 k 878.91 M

empty#spills #events
9.63 k 86.90 M
6.27 k 68.36 M§ 4. Preliminary results

In Ref. [3], it is confirmed that the ηn scattering effect is dominant at the low ηn invariant massMηn (corresponding to the small ηn relative momentum), and that the πn → ηn transition and pn

rescattering effects are small. The differential cross section dσ/dMηn /dΩp of 5% error per MeV bin in
the low Mηn region can determine Re[aηN ] at the precision of 0.1 fm. Currently, the determination ofd3 σ/dMηn /dΩp s are in progress, and just the Mηn distribution has been obtained. The incident photon
energy ranges from 0.82 to 1.26 GeV using the circulating electron energy of 1.32 GeV in the electron
synchrotron [10]. Fig. 2 shows the preliminary Mηn distribution for the γd → ηpn reaction. The

Mηn value is calculated as a d(γ, p) missing mass after the γd → ηpn reaction is identified. Althoughacceptance correction is not yet applied, a clear peak is observed at 0 MeV corresponding to quasi-freeη production from the proton. The momentum calibration of the BLC spectrometer is not completed at16
this moment. Currently, the analysis efficiency is lower than expected, and we try to find the reason.
In addition, the current data statistics is too poor to determine Re[aηN ], and we should continue themeasurement to increase the statistics.

40

Counts / 20 MeV

35

y
r
a

30
25

in

20
15
10

im
l
e

Pr

5
0
-100 -50

0

50 100 150 200 250 300 350 400

Mηn-Mn-Mη (MeV)
Fig.2. Preliminary Mηn distribution for the γd → ηpn reaction. The Mηn value is calculated
as a d(γ, p) missing mass after the γd → ηpn reaction is identified.

§ 5. Silica aerogel counter

The FOREST/BLC experiments also investigate the Λn interaction. This interaction is important tounderstand the baryon-baryon interaction in a comprehensive way. Charge symmetry breaking (CSB) in
the A = 4 hypernuclei is one of the hot topics in hadron physics [13]. The energy difference between the
1+ excited state and ground states are quite different for the mirror A = 4 hypernuclei (4 H and 4 He),and this value cannot reproduced by the theoretical calculations without a large CSB effect. The Λninteraction is expected to play a crucial role for understanding this difference and CSB in hypernuclei.
In the FOREST/BLC experiment, we investigate the Λn interaction through the Λn invariant massMΛn distribution in the γd → K + Λn reaction with K + detection at 0◦ similarly to the ηn interaction

study. The differential cross section d3 σ/dMΛn /dΩK provide the strength of the Λn interaction independently of the Λp. We are now preparing the silica aerogel Cherenkov (AC) counters just in front of
PSH+ to identify K + mesons effectively. The details of the AC counter, and its performance test will bereported in the next annual report.

§ 6. Summary

The first-stage FOREST/BLC experiment, aiming at the determination of the low-energy ηN scat-tering parameters Re[aηN ] and Re[rηN ], started from October 30 in 2017. The number of collected
events for the deuterium target has been 1.6 G up to the end of this fiscal year. The energy and timing
calibrations have been completed for STB-Tagger II, Backward Gamma, and PSH+ detectors, We are17still working on those for the other detectors, and have just started the physics analysis. We should
continue to collect data as soon as possible to determine Re[aηN ] with an accuracy of 0.1 fm.

Acknowledgments
The authors give thanks to the ELPH accelerator staff for their great efforts in the stable operationof the electron synchrotron. They deeply acknowledge S.X. Nakamura and H. Kamano for giving us thepredictions for the ηn rescattering effect in the proposed γd → pηn experiment. This work was sup-ported in part by JSPS KAKENHI Grants Nos. 17340063, 19002003, 24244022, 26400287, 16H02188,
19H01902, and 19H05141.

References[1]

S. Weinberg: Phys. Rev. 137, B672 (1965);
T. Hyodo: Phys. Rev. Lett. 111, 132002 (2013).

[2]

Q. Haider and L.C. Liu: Int. J. Mod. Phys. E 24, 1530009 (2015);
and references therein.

[3]

S.X. Nakamura, H. Kamano, and T. Ishikawa: Phys. Rev. C 96, 042201 (R) (2017).

[4]

A. Matsuyama, T. Sato, T.-S.H. Lee: Phys. Rep. 439, 193 (2007).

[5]

H. Kamano et al.: Phys. Rev. C 88, 035209 (2013).

[6]

T. Ishikawa et al.: Phys. Lett. B 772, 398 (2017);
T. Ishikawa et al.: Phys. Lett. B 789, 413 (2019);
T. Ishikawa et al.: PoS (Hadron2013) 095;
Y. Tsuchikawa et al.: JPS Conf. Proc. 17, 062007 (2017);
T. Ishikawa et al.: PoS (INPC2016) 267.

[7]

T. Ishikawa et al.: Acta. Phys. Polon. B 48, 1801 (2017);
T. Ishikawa et al.: JPS Conf. Proc. 10, 031001 (2016);
T. Ishikawa et al.: JPS Conf. Proc. 13, 020031 (2017);[8]

T. Ishikawa et al.: Nucl. Instrum. and Meth. A 832, 108 (2016).

[9]

T. Ishikawa et al.: Nucl. Instrum. and Meth. A 622, 1 (2010);
T. Ishikawa et al.: Nucl. Instrum. and Meth. A 811, 124 (2016);
Y. Matsumura et al.: Nucl. Instrum. and Meth. A 902, 103 (2018);
Y. Obara et al.: Nucl. Instrum. and Meth. A 932, 108 (2019).

[10] F. Hinode et al.: J. Phys. Conf. Ser. 425, 072011 (2013).
[11] T. Ishikawa et al.: ELPH annual report 2016, 11 (2017).
[12] H. Yamazaki et al.: Nucl. Instrum. Meth. A 536, 70 (2005).
[13] P. Achenbach (A1 collaboration): EPJ Web Conf. 130, 07001 (2016).

18

ELPH Annual Report, Tohoku University (2018)(ELPH Experiment : #2815)

Profile measurement of circulating electrons in asynchrotron using an internal radiator
Y. Obara1 , T. Ishikawa2 , H. Hama2 , F. Hinode2 , H. Kanda3∗ , S. Kashiwagi2 ,M. Miyabe2 , T. Muto2 , K. Ozawa4 , H. Shimizu2 , and A.O. Tokiyasu2
12

Department of Physics, University of Tokyo, Tokyo 113-0033, Japan

Research Center for Electron Photon Science (ELPH), Tohoku University, Sendai 982-0826,
Japan
3

4

Department of Physics, Tohoku University, Sendai 980-8578, Japan

Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization(KEK), Tsukuba 305-0801, JapanAn internal radiator made of a 11-µm-diameter carbon wire is employed to produce bremsstrahlungphoton beams from circulating electrons in a synchrotron at the Research Center for Electron Photon
Science, Tohoku University. The horizontal electron-beam size at the radiator location is determinedfrom the decay rate of the resultant photon intensity as a function of the distance between the fixed radiator position and the centroid of the electron beam. The horizontal beam size at the radiator location
is found to be 0.74 mm with a statical error less than 0.01 mm for 1.3-GeV circulating electrons. The
horizontal correlation between the position and momentum direction of the electron beam is also measured. The horizontal size and correlation are well-reproduced by the design values of the parameters of
the synchrotron. The details are described in a published paper [Y. Obara et al., Nucl. Instrum. Meth. A
922, 108 (2019)].

§ 1. Introduction

The FOREST experiments are conducted at the Research Center for Electron Photon Science (ELPH),

Tohoku University, to investigate the structure of hadrons through meson photoproduction [1, 2] with
the FOREST electromagnetic calorimeter [3]. The experiments use a GeV bremsstrahlung-photon beam,
which is produced from circulating electrons in a synchrotron called Booster STorage (BST) ring [5] byusing an internal radiator made of a carbon wire with a diameter of 11 µm [4]. Currently ELPH is the
only facility having an internal radiator system for producing a bremsstrahlung-photon beam.

§ 2. Horizontal beam size

The horizontal beam size σx is expressed as
√
)2
(
∆p
,
σx = βx ϵx + ηxp∗

Present address: Research Center for Nuclear Physics (RCNP), Osaka University, Ibaraki 567-0047,
Japan

(1)

19
where (αx , βx , γx ) and ϵx denote the Twiss parameters and emittance in the horizontal plane, respectively. The σx is affected by the momentum spread ∆p/p of the beam and by the dispersion ηx . The
design values of the horizontal parameters at normal operation at the radiator location for the 1.3-GeV
circulating electrons are 
1.60 ± 0.09
αx
 


 



 βx   3.70 ± 0.15 m
 


 


.
 γx  =  0.96 ± 0.06 m−1
 


 


−7

 ϵx   (1.375 ± 0.009) × 10 
0.45 ± 0.02 m
ηx(2)

The momentum spread is estimated to be ∆p/p = (6.3 ± 0.0) × 10−4 . A horizontal beam size of σx =0.77 ± 0.01 mm is expected.

We have measured σx with the radiator placed close to the centroid of the circulating electrons. The

production rate of the bremsstrahlung photons is proportional to the number of electrons that hit theradiator. The photon intensity as a function of the time is given by{}I(t) = I0 exp −Γ t .

(3)

Because the decay rate Γ is proportional to the fraction of electrons at the x position of the radiator. The

Γ(x) as a function of x gives the horizontal intensity distribution and σx . The Γ(x) was determined bycounting the number of signals for 16 photon-tagging channels out of 116 for every 0.1 s for a total timeinterval of 120 s. A method to determine σx and development of a special 16-channel 1200-depth 24-bit
scaler were described in the previous annual report [7]. The measured σx of 0.74 mm is consistent withthe expected σx of 0.77 ± 0.01 mm.

§ 3. Horizontal correlation between the position and momentum direction

Because bremsstrahlung photons are emitted along the momentum direction of the initial circulat-

ing electrons, the momentum direction x′ = dpx /dpz can be obtained from the centroid of the intensity
map of the photon beam at downstream. For each fixed x position of the radiator, we measured theintensity map of the photon beam (xBPM , y BPM ) with a developed photon-beam profile monitor (BPM) [6]located 20.8-m downstream from the radiator. To prevent the vignetting, the lead aperture located on thephoton beamline in the GeV-γ experimental hall [4] was removed in this measurement, and the openingof the lead aperture was enlarged (20 mm in diameter) in the second experimental hall.
(µBPM) is determined by fitting a Gaussian function to the xBPM (yBPM ) distribuThe centroid µBPM
xytion of the photon beam. The xBPM and x are shifted by adjusting these values to make x = 0 at the= 0 at x = −3 mm. Fig. 1 shows µBPM
as a function of x. The
centroid of the electron beam, and µBPMxxdecreases with an increase of x. While the expected correlation between µBPM
and x is expressed
µBPM
x
x
as
=x+
µBPM
x

(

)
)
(
αx
αx
−
x zBPM = 1 −zBPM x
βx
βx

(4)

20
with the horizontal Twiss parameters. The corresponding line is also plotted in Fig. 1. Although theas a function of x is almost reproduced in Eq. (4), the slope is steeper in the measurement.
acquired µBPMx
The µy decreases gradually with an increase of x, suggesting that the plane containing the closed orbit
is tilted from the horizontal plane.

10
2
(mm)

1

BPMy

0

0
-5

µ

µ

BPMx

(mm)

5

-1

-10
-2
-15

-4

-3

-2
x (mm)

-1

0

-4

-3

-2
x (mm)-1

0

Fig.1. Horizontal centroid µBPM
and vertical centroid µBPM
of the photon beam as a function ofxythe radiator position x. The solid line in the correlation between µBPM
and x is obtainedxby shifting the correlation Eq. (4) to make µBPM
= 0 at x = −3 mm.
x§ 4. Summary

The horizontal beam size of circulating electrons at the radiator location is estimated from the decayrate of the resulting photon intensity as a function of the distance between the fixed radiator position
and the centroid of the electron beam. The horizontal beam size is determined to be 0.74 mm with astatical error of less than 0.01 mm for 1.3-GeV circulating electrons. The size is well-reproduced by thedesign values of the Twiss and the emittance parameters of the BST ring. The horizontal correlation of
the electron beam between the position and momentum direction is also investigated from the intensity
map of the bremsstrahlung photon beam measured 20.8-m downstream from the radiator location. The
correlation is also well-reproduced by the design values of the BST-ring parameters. The details aredescribed in a published paper [Y. Obara et al., Nucl. Instrum. Meth. A 922, 108 (2019)].

Acknowledgments
The authors express many thanks to the ELPH staff. This work was supported in part by Grants-inAid for Scientific Research (A) No. 24244022, for Scientific Research (C) No. 26400287, and for Scientific
Research (A) No. 16H02188.

References[1]

T. Ishikawa et al.: Phys. Lett. B 772, 398 (2017);
T. Ishikawa et al.: Phys. Lett. B 789, 413 (2019).

21

[2]

S.X. Nakamura, H. Kamano, T. Ishikawa: Phys. Rev. C 96, 042201 (R) (2017);
T. Ishikawa, et al., Acta Phys. Polon. B 48, 1801 (2017).

[3]

T. Ishikawa et al.: Nucl. Instrum. Meth. A 832, 108 (2016).

[4]

T. Ishikawa et al.: Nucl. Instrum. Meth. A 622, 1 (2010).

[5]

F. Hinode et al.: Proceedings of 11th International Conference on Synchrotron Radiation Instrumentation (SRI2012), Journal of Physics: Conference Series 425 (2013) 072011;
F. Hinode et al.: Proceedings of the 7th International Particle Accelerator Conference (IPAC2016),
p. 701.

[6]

T. Ishikawa et al.: Nucl. Instrum. Meth. A 811 (2016) 124;
Y. Matsumura et al.: Nucl. Instrum. Meth. A 902 (2018) 103.

[7]

Y. Obara et al.: ELPH Annual Report 2015, Tohoku University, p. 52 (2016).

22

ELPH Annual Report, Tohoku University (2018)

The performance study of an electromagnetic calorimeter
Foward Gamma
M. Miyabe1 , K. Kanomata1 , and GeV-γ group1
1

Research Center for Electron Photon Science, Tohoku University, Sendai, 982-0826, JapanThe nuclear physics research department of Research Center for Electron PHoton Science (ELPH),
Tohoku University conducts search experiments of nucleon resonance states and mesic nuclei using anelectromagnetic calorimeter. In recent years, experiments are conducted at SPring-8/LEPS2 using thelarge solid angle electromagnetic calorimeter BGOegg. Subsequently, in our group, the forward gamma
ray detector (FG) consisting of 252 PWO crystals is used to compensate for the forward angle, which iscurrently insensitive. The positron beam line in ELPH was used for performance tests, and an energy
resolution of 2.7 % was obtained for 1 GeV positrons. In addition, the angular dependence of incident
gamma could be obtained for the ﬁrst time.

§ 1. Introduction

Hadron photo-production experiment was carried out at SPring-8/LEPS2 from 2014 to 2016 usinga large solid angle electromagnetic calorimeter BGOegg constructed at ELPH. The current BGOegg iscomposed of 1320 BGO crystals, covering a polar angle of 24 to 144 degrees. In this conﬁguration,
BGOegg is insensitive to the region below 24 degrees at forward angle, therefore, by placing the drift
chamber and the Resistive Plate Chamber on the downstream of BGOegg, charged particles are detected
and the solid angle is compensated. In this setup, the η ′ mesic nuclei search experiment is conducted bymeasuring the momentum of the charged particle in the extremely forward angle, but when the decay
gammas from the meson is captured only by BGOegg, the forward region is insensitive. In the regionof Eγ = 2 GeV or more high energy where the multi meson production channel becomes dominant,
it is difﬁcult to evaluate the total cross section of the production. In addition, when investigating theresonance state that generates multiple π 0 and η, such as γp → η ′ → π 0 π 0 ηp reaction, acceptance of theelectromagnetic calorimeter becomes more important. In the future, we plan to cover the front area withthe same shape of BGO crystal. However, our group has produced an another forward gamma detector(Foward Gamma, FG). Our group already developed FG in past and the solid angle of BGOegg can becompensated by adopting this detector. FG is consist of 252 PWO crystals of 22x22x180 mm3 , the widthand height of the sensitive region are 418mm square. If FG is installed at 700mm downstream from thetarget, it will cover 3-16 degrees at forward angle. The remaining 16-24 degrees can cover by adding
about two layers of BGO crystals (in future plan). FG was developed for SPring-8/LEPS experimentswith Backward Gamma detectors [1] from October to November 2003. Evaluated performance of FG

23
at this time is about 4.8 % at π 0 invariant mass resolution corresponding to σmπ0 = 6.7 MeV. Since
these results are more than 10 years ago, the ELPH positron beamline was used for evaluation of theperformance in this time. In particular, evaluation of angular dependence of incident particles andposition resolution of FG depend on simulations, so we need to measure these performance using thepositron beam to determine the actual energy and position resolution.

§ 2. Experimental setup and results

The experiment was conducted in June 2017 at the positron beam line in the GeV-γ irradiation roomof ELPH. FG detector was installed in the positron beam line, and eBPM was installed upstream of the
FG as a positron incident position detector. The experimental setup is shown in Fig. 1. As shown in Fig.

Fig.1. Experimental setup.

Fig.2. The crystal arrangement seen fromthe front of the FG, the shadedpart is the channel used this experiment.

2, 252 PWO crystals are arranged in the front of FG detector. In this experiment, only 25 of these (theshaded area in the ﬁgure) were used. The incident position detector eBPM consists of 16 ﬁbers per layer
and two layers, it detects the x and y position of positrons. While changing the positron energy from 50MeV to 800-MeV, the output light quantity of each 25 crystals around 170th crystal was measured. The
gain of the crystal was adjusted by injecting the beam into the center of each crystal while changing theenergy of the positron beam. After the gain adjustment for all 25 channels was completed, the energy
resolution was evaluated by injecting the positron beam at the center crystal again while changing theenergy.
An energy resolution of 2.67% for 1 GeV positrons is obtained in Figure 3. This value is comparable
to the results of previous experiments [2]. Next, an energy resolution was measured by shifting thebeam incident position by 12 mm from the crystal center which corresponding to the edge region of PWO
crystal. The energy resolution at this incident position was 2.71%. Finally, the energy resolution was
evaluated by changing the angle of FG from 0◦ to 16◦ with the incident position centered on the crystal.

24
The result is shown in Figure 4.
Angular Dependence
σ/Ee+

σ/Ee+ %

Energy resolution
0.18

σ/Ee+ = ( 6.83/Ee+)2+( 0.83/ Ee+)2

0.16

3

2.9

2.8

0.14
0.12

2.7

σ/Ee+ = 2.7% @ 1000 MeV

0.1

2.6

0.08
0.06

a/cos(b*x)

2.5
0.04
0.02
0

100

200

300

400

500

600

700

800
Ee+ (MeV)

Fig.3. Energy resolution obtained when a positronis incident on the crystal center

2.4

−2

0

2

4

6

8

10

12
14
16
Angular (deg)Fig.4. Energy resolution as a function of
the incident angle of the positronbeam§ 3. Summary

We evaluated the performance of the FG detector at the positron beamline in Research Center forElectron PHoton Science, Tohoku University. As a result of the experiment, the FG detector achieved the
expected energy resolution and obtained the new angular dependence data. The simulation parameters
are determined from the obtained data and these results will be used for the analysis of experimental
data using the BGOegg and FG detectors planned in the future. The FG detector that completed theperformance evaluation experiment was transported from ELPH to the SPring-8/LEPS2 experimentalbuilding in February 2018 after replacement of several damaged PMTs, and is currently preparing for
future experiment.

References[1]

T. Ishikawa, ”The FOREST detector for meson photoproduction experiments at ELPH”, Nucl. Instrum. and Meth. A 832, 108 (2016).

[2]

H. Shimizu, ”Performance of a PbWO4 crystal calorimeter for 0.2-1.0 GeV electrons” Nuclear Instruments and Methods in Physics Research A 447 (2000) 467-475

ELPH Annual Report, Tohoku University (2018)25(ELPH Experiment : #2848)

Photo-production of a Neutral Kaon and/or a Lambda
Hyperon on a deuteron near the threshold
Masashi Kaneta1 for the NKS2 collaboration
1

Department of Physics, Graduate School of Science, Tohoku University, Sendai, 980-8578

The NKS2 spectrometer and photon tagging system had been damaged due to the 2011 off the Paciﬁc coast of Tohoku Earthquake. The experiment was conducted to show that the detector performance
was sufﬁcient after the recovery.

§ 1. Introduction

We had been studying the strangeness photo-production near the threshold using NKS2 spectrom-eter in the 2nd experimental hall at ELPH. The reaction we focus is γ + d → K 0 + Λ + (p). The photon

beam was generated by the bremsstrahlung using a carbon wire in the BST ring, and tagged by thephoton tagging system (tagger). The original tagger was damaged by the aftermath of the 2011 off the
Paciﬁc coast of Tohoku Earthquake. We developed and constructed new tagger using SiPM (MPPC by
HAMAMATSU photonics) and plastic scintillator. The proposed experiment was the performance test of
NKS2 spectrometer and tagger system. We will report that the while system is ready to the measurement using Λ measurement. This report is based on master’s thesis of Ms. Ninomiya [1]§ 2. Result of Λ analysis

The data was taken in Jun, 2016. We did not cover while energy coverage of tagger due to limited

number of circuit module at that moment. we concentrated in high energy region (up to Eγ = 1.264 GeV
in design value) to record the data, because the new tagger covered higher energy region than previous
tagger (up to Eγ = 1.1 GeV). We set two-particle trigger for the data taking.
The particle identiﬁcation was done by using Time-Of-Flight (TOF) and momenta. The TOF wascomputed hit timing information from Inner Hodoscope (IH) and Outer Hodoscope (OH). The momentum
and ﬂight path were reconstructed drift time information of Cylindrical Drift Chamber (CDC) and Vertex
Drift Chamber (VDC). The detail information of the NKS2 spectrometer and tagger can be found in
elsewhere. [2, 3]
After selecting proton and negative pion candidate, we adopted three type of cuts to reduce thebackground. We named those cuts as opening angle cut, decay volume cut, missing mass cut, andinvariant mass cut.
The opening-angle (θ) cut was applied to reject electron-positron pair event. We selected event
which had the π − p candidate and opening angle between the two particles in −0.9 < cos θ < 0.9.

26
We reconstructed the decay position as midpoint on the distance-closed-approach of p and π − trajectories. Part of the Λ decayed in outer region of the target cell because of weak decay. We requested
that the decay point was out of the target cell to reduce accidental background.
The missing mass of the reaction γ + n → p + π − + X is shown in Fig. 1. We assumed the rest ofneutron in this calculation. Because of Fermi motion of the neutron in the deuteron, we saw the wider

Countsdistribution than expected Kaon mass distribution.

Missing mass [GeV/c2]
Fig.1. Missing mass distribution of X in γ + n → p + π − + X reaction
The ﬁnal cut to select Λ is the invariant mass selection. To increase the accuracy of particle identiﬁ-

Missing mass [GeV/c2]

cation, we checked correlations of the missing mass and invariant mass. Figure 2 shows the correlations.

pπ- invariant mass [GeV/c2]

Fig.2. Correlation of the missing mass (MX ) in γ + n → p + π − + X reaction and the invariant
mass of pπ − . The lines indicate the region selected as Kaon candidates (0.4 ≤ MX ≤ 0.6
GeV/c2 ).
We chose the missing mass region in 0.4 - 0.6 GeV/c2 as Kaon candidates. After selecting the region,
we obtained the invariant mass distribution shown in Fig. 3. We saw the peak around 1116 MeV/c2 inthe ﬁgure. We obtained that the peak position is 1113.6 ± 0.6 MeV/c2 and σ is 4.8±0.6 0.6 MeV/c2 . The

number of Λ is 138±15 with selecting ±3σ region.

Counts27

pπ- invariant mass [GeV/c2]

Fig.3. The invariant mass distribution of pπ − after the missing mass cut. The curve is a ﬁt
result of Gaussian + 3rd order of polynomial.

§ 3. Summary

The orbit electron energy became 1.3 GeV from 1.2 GeV with update of the electron synchrotron. We

developed and installed new tagger system along with the update. Current maximum energy of tagged
photon is 1.264 GeV.
We carried out the experiment of strangeness photo-production using liquid deuterium target with
1.3 GeV electron energy. The data was analyzed and we obtained the identiﬁed Λ. The peak position ofinvariant mass of Λ was close to PDG value. On continuing the analysis, we will obtain the cross-sectionof Λ in photon beam energy region that NKS2 have not.

Acknowledgment
We would like to express our gratitude for the maintaining the accelerator operation of the accelerator group. We appreciate the engineering/technical staff, Mr. Umetsu for his support in the developing and construction of new tagger. This work is partly supported by JSPS Grant-in-Aid for Creative
Research Program (16GS0201), JSPS Core-to-Core program (21002), JSPS Grant-in-Aid for ScientiﬁcResearch (C) (23540334), and JSPS Grant-in-Aid for Scientiﬁc Research (A) (17H01121).

References[1]

二宮亜紀 2017 修士論文「η 中間子および Λ 粒子光生成反応を用いた新光標識化装置の性能評価」.

[2]

H. Yamazaki et al.: Nucl. Instrum. Meth. A536 (2005) 70-68.

[3]

M. Kaneta et al.: Nucl. Instrum. Meth. A886 (2018) 88-103.

28

ELPH Annual Report, Tohoku University (2018)(ELPH Experiment : #2880)

The performance test for the time resolution of Multi-gap
Resistive Plate Chamber (one of the experimental courses
in Graduate Program on Physics for the Universe
curriculum in Tohoku University)
Masashi Kaneta1 , Toshiyuki Gogami1,∗ , and Satoshi N. Nakamura1
1

Department of Physics, Graduate School of Science, Tohoku University, Sendai, 980-8578

This text experiment was carried out as one of the experimental courses in Graduate Program on
Physics for the Universe (GP-PU) curriculum in Tohoku University. In this course, we requested tomaster analysis method of the intrinsic timing resolution from three combinations of Time-Of-Flightfrom three different counters.

§ 1. The GP-PU program and the experimental course

The GP-PU program is a part of the international joint graduate school programs. The Head of thedivision for the programs addresses the programs as the following. “The International Joint Graduate
School Programs have been / will be established under the Division for International Joint Graduate
Degree Programs, through strong collaboration with influential universities overseas in order to spread
Tohoku University’s expertise beyond the bounds of existing educational systems. Based on an analysis
of Tohoku University’s potential and strengths, the programs’ fields w ill t ackle issues and global problems confronting humanity, promise future development, and lead the global community, exhibiting thecapabilities of Tohoku University.” [1]The GP-PU students need to take additional classes: the GP-PU seminar, the GP-PU experiment,
and the GP-PU school. The GP-PU experiments cover the field o f e lemental p article p hysics, nuclear
physics, and cosmology. “A role of the program is to make students learn a comprehensive view, which
can be utilized to be a leader for either academic or other jobs after graduation, through classes in which
cutting-edge experimental apparatuses and techniques are introduced and used. ” [2]This test experiment is one of the GP-PU experiments and the GP-PU students had the following
experience. (1) Construction of a test bench for detector test using cosmic-ray. (2) Assembling of Multigap Resistive Plate Chamber (MRPC) (3) Performance study by cosmic-ray and electron/positron beam.

§ 2. Multi-gap Resistive Plate Chamber

Figure 1 shows the structure of MRPC. It was consisted from two stack of five-gap spacing.

∗Present address: Department of Physics, Graduate School of Science, Kyoto University, Kyoto, 606-8502

29

Table 1. Size of materials for MRPC
Parts
Resistive plate
Insulator
Read-out pad
SpacerElectrode

Material
Soda-lime glass
Glass-epoxy
Gold plating copper
Fishing wire
Adhesive carbon tape

Read out pad(Anode side)
PCB
Glass-epoxy(t = 0.6 mm)

Read out pad(Cathode side)
Read out pad(Anode side)

size
100W × 480H × 0.4T [mm3 ]120W × 500H × 0.6T [mm3 ]40W × 460H × 0.018T [mm3 ] (rectangle region)
No.2, ∅ 0.235 mm
100W × 480H × 0.09T [mm3 ]Carbon tape
(Anode side)
Fishing wire
(φ 0.235 mm)
Soda-lime glass(t = 0.4 mm)
Carbon tape(Cathode side)
Carbon tape
(Anode side)
Read out pad
PCB

Fig.1.

Structure of MRPC seen from side is shown in top. The bottom figure is the top view withcorrect aspect ratio.

We used 0.4 mm thickness soda-lime glasses for resistive plates. The gas spacing was kept by No. 2
fishing wire (0.235 mm diameter). The read-out pad and the electrode were on the glass-epoxy plate (0.6mm thickness) and made as a printed circuit board. The electrode was covered by an adhesive carbon
tape to increase the resister of the electrode and to decrease charge spread. The summary of material islisted in Table 1.
MRPC was fixed in a box and chamber gas was flowed in the box. We used mixed gas of R-134a(90%) and SF6 (10%).
The high voltage was applied from outsize via SHV connector. The signal was read through aconnector on the side plate of the box. We set an amplifier circuit on outside of the box. Figure 2 shows
the circuit diagram of the amplifier.
We only used the anode signal from MRPC. In the first stage, there were resisters in both channelsof the anode ant the cathode for the impedance matching. We set differentiator before the non-inverting
amplifier in order to get a sharp rising signal. The operation amplifier we chose was AD8000 provided
by Analog Devices. The values of resister and capacitor are listed in Table 2. The signal line and circuitboard are shown in Fig. 3.

30

Table 2. Parameter of resister and capacitor.
Parts
values
R
34 Ω
R2
100 Ω
R3
20 Ω
R4
2k Ω
R5
51 Ω
C1
100 pFC2
0.1 µF
C3, C5 1000 pF
C4, C60.1 µF
5V
VCC
-5 V
VEE

Non-inverting
apmplifier

Impedance
matching

Differentiator

Fig.2.

Circuit diagram of the amplifier for the MRPC.
Anode
Grand
CathodeInside of the box
Outside of the box

Signal line
Power line
for the amplifierFig.3.

Photo of amplifier.

31
Note that we also carried the impedance matching test with changing the register value. It will bereported as another manuscript (ELPH experiment: #2890) because of the different proposal to PAC.

§ 3. The set-up of the experiment

We used the positron beam line in the GeV-γ experimental room. Figure 4 shows the set-up of theexperiments. We put the two finger counters, a veto counter, MRPC box, two reference counters, and one
finger counter from upstream side.
Three finger counters (single side readout by PMT) was used to guarantee the beam position. The
veto counter has a hole (shape: 1 cm × 1 cm square) was located at downstream of two finger counters to

avoid counting of beam halo by scattering. We used two thick plastic scintillation counters (double side
readout by PMT) as the reference counter of Time-Of-Flight (TOF).

Side view

MRPC
box

Fingercounter

Positron beam

Finger counters
Veto counter

Top view

Reference counterof TOF~ 60 cm
Stage
plate

~ 100 cm

Positron beam

MRPC box can be moved
to check position dependecesof the timing resolution andthe efficiency

Fig.4.

Detector alignment of the experiment are shown. The top figure is the side view and thepositron beam travel from left-hand side to right-hand side. The bottom figure is the top
view.

32
We tested beam rate dependence of TOF resolution. The positron beam was generated by electronpositron conversion of gamma beam with a metal target. We used three metals that are prepared in
GeV-γ experimental room. The beam rate is defined by the coincidence signal rate among three finger
counters and veto counter. If the veto counter had a hit in the same timing with three coincidence of
three finger counter, the event was excluded.
The following list is the summary of target materials and beam rates.
• Gold (radiation length 0.006 X0 ): 160 Hz/cm2• Tungsten (radiation length 0.06 X0 ): 320 Hz/cm2• Brass (radiation length 0.6 X0 ): 570 Hz/cm2§ 4. Results

The intrinsic timing resolution of MRPC was computed via three combination of TOF resolution of

combination of two of three counters (TOF1, TOF2, and MRPC). Figure 5 shows the timing resolution of
MRPC. The resolution became better (smaller value) with increasing the high voltage. With increasing
the beam rate, the resolution is getting worse.
The typical timing resolution of MRPC is about 100 ps. The results were worse than that value.
The additional test to investigate the reason was done by using cosmic-ray. The detail discussion will be

Timing resolution [ps]found the other manuscript (ELPH Experiment: #2890) of the annual report.

High voltage [kV]Fig.5.

The intrinsic timing resolution of MRPC as a function of induced high voltage for threedifferent beam rates.

§ 5. Summary

The experiment of performance test of Multi-gap Resistive Plate Chamber was carried out as oneof the experimental courses in Graduate Program on Physics for the Universe curriculum in Tohoku
University. The student had the experience of the process in elementary particle and nuclear physics.

33

Acknowledgment
We thank the accelerator staff of ELPH to provide the stable operation of accelerator. The experiment was supported by GP-PU program.

References[1]

http://ijg.pgd.tohoku.ac.jp/english/message/index.html[2]

http://lambda.phys.tohoku.ac.jp/gppu/exp/

34

ELPH Annual Report, Tohoku University (2018)(ELPH Experiment : #2890)

The performance test of the amplifier for Multi-gap
Resistive Plate Chamber
Masashi Kaneta1 for the NKS2 collaboration
1

Department of Physics, Graduate School of Science, Tohoku University, Sendai, 980-8578

We are planning the Λn interaction measurement via the final state interaction (FSI) in γ + d →K + + Λ + (n) reaction. We proposed the measurement of K + cross-section in that reaction to obtainthe FSI effect. The separation of Kaon from pion and proton is the essential for the experiment. The
Multi-gap resistive Plate Chamber is adopted for the new TOF counter of Kaon identification. We tested
different setting of amplifier circuit board to evaluate the timing resolution and the efficiency.

§ 1. Introduction

We have been developing The Multi-gap Resistive Plate Chamber (MRPC) as a high-resolution

Time-Of-Flight detector for the NKS2 experiment. The requirement of the timing resolution is less than
120 ps to separate π/K/p with combination of IH as the start counter of TOF. The signal of MRPC issmaller than PMT and then we need to use an amplifier. We had tested the amplifier circuit in the same
beam time of ELPH Experiment: #2880. The description of the structure of MRPC, the amplifier circuit,and the setup of the test experiment are shown in the annual report of the #2880.
The LEPS group reported that they needed to impedance matching circuit between MRPC andamplifier to avoid a reflection. The effect of reflection caused a reduction in timing resolution. We
adopted the matching circuit in our amplifier circuit board.
Note that the detail discussion of the test is shown in Master’s thesis of Mr. Takeuchi [1].

§ 2. Amplifier circuit

Figure 1 shows the circuit diagram of the amplifier. We selected circuit parameters with a circuit

simulator LTSpice. Before the beam time, we selected the two candidate of register value (34 and 43 Ω)with MRPC signal by cosmic-rays.
To distinguish between MRPC performance and circuit performance, the circuit’s rate tolerance wastested. We didn’t see pile-up and changing the shape of output signals in 5 MHz (200 ns interval) of 50
ns width input signals. We expected 10 kHz maximum hit rates in MRPC and then the rate tolerance of
MRPC would not be limited by the circuit.

35

Non-inverting
apmplifier

Impedance
matching

Differentiator

Fig.1.

Circuit diagram of the amplifier for the MRPC.

§ 3. Results

3.1 Beam rate and matching register dependence
The intrinsic timing resolution of MRPC was computed via three combination of TOF resolution of

combination of two of three counters (TOF1, TOF2, and MRPC). Figure 2 shows the timing resolution of
MRPC. The resolution became better (smaller value) with increasing the high voltage. With increasing
the beam rate, the resolution is getting worse.
The typical timing resolution of MRPC is about 100 ps. The results were worse than that value.
The additional test to investigate the reason was done by using cosmic-ray.
The detection efficiency of MRPC is defined by the fraction of MRPC hits to trigger hits. The highvoltage dependence of the efficiency is shown in Fig. 3.
The timing resolution and the detection efficiency seems to be the best with 16 kV high voltage with43 Ω matching register. The best value of efficiency is about 98 to 99% that are the same with typical

Timing resolution [ps]Timing resolution [ps]values of MRPC.

High voltage [kV]Fig.2.

High voltage [kV]The intrinsic timing resolution of MRPC as a function of induced high voltage for threedifferent beam rates. We used 34 Ω and 43 Ω register for the impedance matching andshow left- and right-hand side, respectively.

Detection effeciency [%]Detection effeciency [%]36

High voltage [kV]Fig.3.

High voltage [kV]The detection efficiency of MRPC as a function hit position. We used 34 Ω and 43 Ω
register for the impedance matching and show left- and right-hand side, respectively.

3.2 Hit position dependence
Figures 4 and 5 show the hit position dependence of the intrinsic timing resolution and the detection
efficiency, respectively. The high voltage was fixed as 16 kV and the beam rate is 320 Hz/cm2 (converter:
Tungsten). The left and right was defined as view seen from upstream side.
The results showed that there was position dependence in the timing resolution and the efficiency.
If the reason was the reflection of signal, we expected the same dependence in the timing resolution andthe efficiency. We guessed that it was due to insufficient gas replacement time and a noise because ofTiming resoluation [ps]the weak connection between MRPC and the amplifier circuit.

Beam position [cm]Positron beam
direction
Fig.4.

The intrinsic timing resolution of MRPC as a function of induced high voltage for threedifferent beam rate. We used 43 Ω register for the impedance matching.

Detection efficiency [%]37

Beam position [cm]Positron beam
direction

Fig.5.

The detection efficiency of MRPC as a function of hit position. We used 43 Ω register for
the impedance matching.

§ 4. Cosmic-ray test

The performance test with positron beam did not show the sufficient result we expected. We intro-

duced longer gas replacement time and additional grand lines.
Before the beam time, we used 3 days for the gas replacement with 30 cc/min flow. We took 10 days
for the replacement with 30 cc/min flow before the cosmic-day test.
The reference counters we used in the test is the same plastic scintillation counters with the beam
test. Table 1 shows the summary of the intrinsic timing resolution comparing the beam test. The result
met our request (σtiming < 120 ps).
Table 1. The intrinsic timing resolution of cosmic-ray test.
Induced high voltage [kV]
16.0
15.6

Intrinsic timing resolution of MRPC [ps]Cosmic-ray test
Beam test
118.8 ± 2.3
150.1 ± 1.9
128.1 ± 2.7
147.2 ± 1.7§ 5. Summary

We tested two different impedance matching resister on the amplifier circuit board of MRPC in the

GeV-γ experimental room at ELPH. The detection efficiency of MRPC tested was about 98 to 99% andit was the same value with typical value of general MRPCs. The timing resolution was not reached 100
ps we expected and there were hit position dependence in the timing resolution and the efficiency. We
conclude the worse timing resolution and position dependence were due to less time of gas replacement.
After 10 days of gas replacement time, the timing resolution was about 120 ps in the test with cosmic-ray.
The resolution was sufficient the request of π/K/p separation in the future experiment.

38

Acknowledgment
We thanks the accelerator staff of ELPH to provide the stable operation of accelerator.

References[1]

竹内大貴 2018 修士論文「Λn 終状態相互作用研究に向けたMulti-gaps Resistive Plate Chamber の開発」)

ELPH Annual Report, Tohoku University (2018)39(ELPH Experiment : #2899)

Development for the resistive plate chamber (RPC)
Yuto ISHIZUKI∗ , Jumpei TAKAHASHI∗ , Daisuke TAKI∗ , Kento TERADA∗ ,and Hiroaki Ohnishi∗§ 1. Introduction

The resistive plate chamber (RPC) is one of the key technologies for Time of Flight (ToF) measure-ment these days. Figure 1 shows a typical structure of the RPC, which consists of thin glasses with thingaps made with 0.26 mm diameter fishing line. The most outside of the glass will be covered by a highresistive electrode to apply high voltage on the detector. A produced signal will be read out by the pickup
electrode, which is placed outside of the high resistive electrode with 0.4mm thick G10 plate in between.
According to the previous experiences, a thin gap will improve timing resolution, however, the efficiency

Fig.1. Schematic view of the typical RPC.
of the detector will be reduced. To overcome the reduction of efficiency, multi gap configuration, whichis shown in Figure 1, has been proposed and used as high efficiency and high time resolution detector
technology nowadays.
Advantages to use RPC for ToF detector is as follows. First of all, the detector is not using photomultipliers(PMT); thus, the RPC has strong capability against the magnetic field. Second, the RPC willshow quite good time resolution, which is an order of 50 ps, and high efficiency, which is more than 99%
at the same time. At last, the main component of the RPC is thin glasses. Thus, the construction cost of
RPC can be reduced, by keeping high performance, concerning ordinary ToF detector, which consists ofscintillator and PMTs. Because of the reasons listed above, RPC is chosen as the primary choice of the
ToF detector for high energy and nuclear physics, especially if they need a large area detector.

∗

Present address: Research Center for Electron Photon Science, Tohoku University, Sendai, 982-0826

40
For instance, large area RPC, such as 2 m long detector has already constructed for the LEPS2
experiment at SPring-8 [1]. Shortly, construction of new large area ToF detector is planing for J-PARC
experiment [2]. For the LEPS2/RPC construction, adhesive carbon tapes [3] has been used as the highresistive electrode, because it is easy to use. Moreover, it was commercially available. However, theproduction of the carbon adhesive tape which has been used was discontinued to date. Therefore, weneed to find an alternative solution for the high resistive electrode for future RPC production. As aresult of investigating the previous researches, we find high resistive paint is widely used as a resistive
electrode for RPC worldwide. In this report, we show the first trial to produce RPC by using highresistive paint as a high resistive electrode.

§ 2. Resistive paintThe resistive electrode is one of the important element to construct the RPC. The resistivity is very

important. It controls cross-talks on signals in the readout electrode. The requirement of the resistivity
for the detector electrode is needed to have an order of 103 − 106 Ω/sq. We found two candidates on themarket. One is COLCOAT PS-2002 by COLCOATCO. Ltd. [4] and the other is SEPLEGYDA AS-MO4D

produced by Shin-Etu polymer Co.Ltd. [5]. Table 2 shows basic properties for those paints. That paintseems suitable for the RPC, because the resistivity can be controllable by the thinness of the paint andthe paint is water-soluble, I.e., it is not necessary to prepare the organic solvent facility.
Name
COLCOAT PS-2002
SEPLEGYDA AS-MO4D

Main conductive materials
Antimony-doped tin oxide
Polythiophene

solvent
water / alcohol
water / alcohol

surface resistivity [Ω/sq.]106 ∼ 107
106

Table 1. Properties of the paint we are used for this test.

Fig.2. Pictures of painted glasses, without (a) and with (b) surface treatment.

§ 3. Painting on glasses

First of all, we tried to paint on the glass surface that we chose earlier. The results are shown in

the Fig 2.-(a) It was found that the paint cannot be applied uniformly due to the volatility of the glass.

41
During the discussion with the producer of the paint, they suggested to wash the glass surface by acid,to roughen the surface of the glass. The result is shown in Fig 2-(b). Finally, we succeeded to paintglass surface with the selected paint. Figure 3 shows the relation between paint thickness and volume
resistivity. The target thickness of the paint was 35µm. However, the actual thickness measured wasscattered about 10-40µm. The result indicates difficulty to control the thickness of the paint. On theother hand, surface resistivity for all paint samples are shown similar value, which is ∼ 105 Ω/sq.

Fig.3. Correlation between surface resistivity and paint thickness. Clear correlation has notseen.

§ 4. Detector construction

By using the glasses with resistive paint on it, a single gap type of the RPC has been constructed.

The size of glass is 55 mm × 80 mm and 1.8 mm thick. The gap of the RPC is set to 0.5 mm, which is kept

by 0.5 mm Acrylic plate as a spacer. Signal pick up electrode made with Copper adhesive tape is placedoutside of paint electrode with 1.6 mm thick G10 plate in between. For the reference, we also produce
an RPC with Adhesive carbon tape, which is used for LEPS2-RPC. Figure 4 shows constructed RPCs.
For the test experiment, the standard gas mixture for RPC, i.e., R134a : C4H10 : SF 6 = 90 : 5 : 5 wasused. The initial test has been performed with cosmic rays. The obtained raw signal is shown in Fig 5
The result indicates that the pained electrode seems to work correctly as a resistive electrode. Thoseconstructed detectors are tested with positron beam at ELPH.

§ 5. Test experiment with positron beam at GeV-γ experimental hall

The test experiment is performed with a positron beam at the GeV-γ experimental hall. Bremsstrahlung

γ-ray radiated in BST ring is delivered to the GeV-γ experimental hall. The γ-ray was converted to theelectron-positron pairs in the thin lead target which is located in front of the Tag-X magnet. Converted
positrons are selected by Tag-X magnetic field and delivered to test experiment area. The momentum of
the positrons is selected to be 600 MeV for the test experiment. The typical intensity of the positron isabout 300 Hz/cm2 . The experimental setup is shown in Fig.6.

42

Fig.4. Constructed test detector.

Fig.5. Cosmic ray signal seen by RPC withpained electrode.

Fig.6. Schematic view of the experimental test setup and a picture during experiment§ 6. Results and Discussion

Figure 7 shows detector efficiency as a function of applied voltage. Red(Blue) points show theefficiency of the RPC constructed with paint (ordinary Carbon tape) as resistive electrodes. Both RPC
show the efficiency plato ∼ 60% efficiency, which indicates that painted electrode is working as same asordinary Carbon electrode.

To understand the result obtained above, we performed detector simulation by using the detector
model describing in the Refrence [6]. The simulation result tells us that the detector efficiency for thisconfiguration must be closed to ∼ 98% or more. We employee parameter scan for the detector simulation

to match the simulated results to the result obtained by the test experiment. The possible parameterswhich may make worth detector efficiency will be gap distance and applied voltage. In the simulation,even if we reduced Gap distance down to 0.3 mm, the efficiency is as much as ∼ 80%, which is stillinconsistent with the test experiment. It should be noted, we use relatively thick glass for this test, ı.e.,
1.8 mm. Also, we construct a small detector. Thus, It is tough to believe the reason for the low efficiency
is coming from gap distance. The applied voltage between the gap is one of another possible source.
However, for this test, we do not have a way to measure the electric field between the gap directly. Thus,
we have no way to deny this possibility at this moment. Another possibility is, for this test detector, we
are using relatively large area space to keep gap distance. If there is surface current flow through thedetector, the effective electric field might be reduced. This can be tested with changing spacer to other43

Fig.7. Detector efficiency as a function of applied voltage.
materials. Further investigation should be needed to find the reason.

§ 7. Summary

The RPC now becomes one of the standard detectors for ToF measurement. Unfortunately, thewidely used resistive electrode is not available anymore. Therefore study to found an alternative solution
is mandatory. We are trying to produce RPC with high resistivity paint as the electrode. The results
indicate promising results. However, many difficulties are found, such as how to control the thickness ofpaint, uniformity, so forth.
The test experiment has been performed at ELPH by using a positron beam. The result shows
similar performance, both ordinary carbon tape, and paint electrode. However, overall detector efficiency
seems too low for both detectors compared to the detector simulation results. The reason is now underinvestigation.

Acknowledgment
We are grateful to the all staff members of ELPH for their extensive efforts on the successful operation of the facility. This work is partly supported by the MEXT Grants-in-Aid for Scientific Research on
Innovative Areas “Clustering as a window on the hierarchical structure of quantum systems” Group-A02(18H05402).

References[1]

K. Watanabe et al. Nucl. Instrum. Meth. A 925(2019)188[2]

J-PARC E50 proposal, see http://j-parc.jp/reseacher/Hadron/en/Proposal e.html[3]

https://www.esd-emi.com[4]

https://www.colcoat.co.jp/images/chemical/pdf/kinousei 07.pdf[5]https://www.shinpoly.co.jp/product/material/seplegyda/seplegyda.html[6]Werner Riegler et al. Nucl. Instrum. Meth. A 500 (2003)144.

44

ELPH Annual Report, Tohoku University (2018)(ELPH Experiment : #2900)

Performance evaluation of a scintillating fiber detector forthe high-momentum secondary beamline at J-PARC
T. Aramaki1 , T. Akaishi2 , H. Asano3 , C.-Y. Chang4 , W.-C. Chang4 , R. Honda1 ,Y. Igarashi5 , T. Ishikawa6 , S. Kajikawa1 , Y. Ma3 , K. Nagai4 , H. Noumi7,5 ,H. Sako8 , K. Shirotori7 , T.N. Takahashi7 ,and for the J-PARC E50 collaboration
1
2

Department of Physics, Tohoku University, Sendai 980-8578, Japan

Department of Physics, Osaka University, Toyonaka 560-0043, Japan
3
4

5

Meson Science Laboratory, RIKEN, Wako, 351-0198, Japan

Institute of Physics, Academia Sinica, Taipei 11529, Taiwan

Institute of Particle and Nuclear Studies(IPNS), High Energy Accelerator Research
Organization (KEK), Tsukuba 305-0801, Japan

6

Research Center for Electron Photon Science(ELPH), Tohoku University, Sendai 982-0826,
Japan

7

Research Center for Nuclear Physics (RCNP), Osaka University, Ibaraki, Osaka 567-0047,
Japan

8

Advanced Science Research Center (ASRC), Japan Atomic Energy Agency (JAEA), Tokai,
Ibaraki 319-1195, JapanWe are currently developing a scintillating-fiber tracker for the high-momentum secondary beam at
the Japan Proton Accelerator Research Complex (J-PARC). The intensity of the beam is expected to be 60
M/spill with a spill duration of 2 s. The fiber tracker is required to measure the position of each charged
particle in the high-intensity beam. A prototype of the tracker consists of scintillating fibers with adiameter of 1 mm. Each fiber is connected to a multi-pixel photon counter (MPPC), Hamamatsu S133601350PE. We have studied the performance of the prototype using electrons and positrons converted fromthe high-intensity bremsstrahlung-photon beam at the Research Center for Electron Photon Science(ELPH), Tohoku University. Signals from the MPPCs are directly input to an EASIROC module, andthe digitized data are acquired with a developed streaming data acquisition (DAQ) system. The time
resolution obtained is better than 1.0 ns at a counting rate of 1 MHz for each fiber. The detection
efficiency decreases as the intensity increases. This is caused by a gain drop owing to the over current
and by a counting loss owing to a pile-up in the EASIROC chip. The dead time of the EASIROC chip isfound to be 48 ns, giving 5% counting loss at 1 MHz for each fiber.

§ 1. Introduction

We plan to perform a high-statistic Λp scattering experiment. The purpose of this experimentis to investigate the ΛN interaction precisely, especially for the partials waves more that the P wave.
Nowadays, the many-body force among Λ and nucleons is considered as a key to solve the hyperon puzzle

45of the neutron star [1]- [2]. However, present Λp scattering data is not enough precise to discuss the
many-body ΛN force from hypernuclear data. Thus, we plan to perform the Λp scattering experiment inthe Λ beam momentum range from 0.4 to 2 GeV/c.
The experiment will be performed at the planned high-momentum beamline in the hadron facility
in J-PARC. We use a forward spectrometer and a streaming data acquisition (DAQ) system for charmed
baryon spectroscopy at the J-PARC E50 physics program [3]. The Λp scattering can share the E50
experimental setup with the main program. The advantage of sharing the E50 experimental setup isthat the Λp scattering data can be acquired in parallel with other experiments owing to the streaming
DAQ system. The high-intensity secondary beam with 60 M/spill (spill duration of 2 s) is provided using
a dispersion matching technique on the high momentum beamline. Since the momentum of the beam
particle is different for different horizontal position, we need a tracker device for the beam which can be
operated in the high-intensity environment. We are currently developing a scintillating fiber tracker asa tracker device. In this report, we show the performance of the prototype fiber tracker in response toelectrons and positron converted from the high-intensity bremsstrahlung-photon beam at ELPH.

§ 2. Scintillation fiber tracker

The prototype fiber tracker consists of scintillating fibers with a diameter of 1 mm, and the max-

imum singles rate is expected to be 1 MHz for each fiber. The position resolution of 200 µm and thedetection efficiency of 97 % per layer are required for the beam momentum resolution and the beam
discrimination efficiency. In addition, the time resolution of 1.0 ns is necessary in order to suppress
accidental coincidence.
2.1 Prototype scintillating fiber tracker
The prototype fiber tracker consists of four position detector, each of which is comprised of threelayers of fiber hodoscopes oriented to the x, u, and v direction. The prototype fiber tracker has 12 layers
in total. In an x-oriented layer, fibers are placed along the y-axis giving the x position from a hit fiber. In
a u(v)-oriented, fibers are placed along the direction tilted by 30◦ (−30◦ ) against the y-axis. Fig.1 showsa photo of the prototype fiber tracker, definition of the axes, placement of fibers in the three layers, andits cross-sectional view. In each layer, fibers are arranged in a staggered relation, and two adjacent fibers
overlap a 0.5 mm width. The number fibers is 12, 10, and 10 for x, u, and v layers, respectively, giving
the number of the readout channels is 128 in total. Each fiber is connected to a MPPC( [4]) to readout
the scintillation light, and the signal from MPPC is transferred to the NIM EASIROC module.
2.2 NIM EASIROC module
The EASIROC chip [5] has all essential functions to operate MPPC and readout signals from it.
The number of readout channels is 32 in a chip. The EASIROC chip has a pre-amplifier, a shaper,and discriminator. The chip also has a digital analog converter (InputDAC) function for adjusting thebias voltage to operate MPPC, wihch is controlled by a field-programmable gate array (FPGA). The NIM
EASIROC module is contains two EASIROC chips and a FPGA chip, and the number of readout channels

46

Fig.1. Prototype scintillating fiber tracker. The figure (a), (b) and (c) show a photo of the prototype fiber tracker, placement of fibers in the three layers, and its cross-sectional view.

is 64 in total. The timing signal form an EASIROC chip is transferred to a prototype streaming TDC
and sent to personal computer.

§ 3. The prototype streaming TDC system

In this section, we describe the front-end electronics in the prototype system.

3.1 Hadron universal logic module
The data-streaming-type TDC (streaming TDC) is implemented into an FPGA chip on the hadron
universal logic (HUL) module, which is a multi-purpose module developed for hadron experiments at
J-PARC. The block diagram of HUL is shown in Fig. 2. The HUL module is the VME 6U size module,
and is a kind of the digital module having an FPGA chip, Xilinx Kintex-7, XC7K160T-1FBG676 [6] anddoes not involve any analog parts such as an amplifier or ADC. The front input ports are connected to
the FPGA chip through the differential signal buffers. The back J0 connector is the trigger transceiver
port based on the KEK-VME standard [7]. The J1 connector is used only for the power supply. Instead,a giga-bit Ethernet PHY is mounted and the data communication is realized by silicon TCP (SiTCP)
implemented in FPGA [8]. The band width of this module is limited to 1 Gbps. An important feature is
the mezzanine slots allowing us to expand HUL functions. The master clock transceiver port is given byusing the mezzanine card.
3.2 Master clock distributor
The master clock is used to synchronize the streaming TDC among the HUL modules. The masterclock distributor (MCD) is a HUL mezzanine card providing the master clock transceiver function inorder to connect the master HUL module sending the master clock and the slave HUL modules. This
MCD card can treat the signals, which is compatible with the Belle-2 trigger [9]. The signals are transported via a twisted pair cable. Two signals from the master to the slave are defined as CLK and TRG.
On the other hand, other two from the slave to the master are defined as ACK and RSV. The MCD card

47

Fig.2. Block diagram of HUL. The HUL module has two input ports on the front panel andtwo mezzanine card slots. These four are connected to FPGA directly. A LAN port ismounted on the front panel. Giga-bit Ethernet communication can be used with SiTCP
implemented in FPGA.

has five ports. One is connected to the upstream module and the other four are connected to the downstream modules. Thus, cascading connections are allowed among MCDs. The CLK pins on these ports
are connected to the jitters cleaner, LMK03318.
In this experiment, six HULs were synchronized using cascaded MCD by the 50 MHz master clock.
However, the TRG lines were used to distribute the clock instead of the CLK line for simplicity.
3.3 Prototype streaming TDC
The data streaming type TDC implemented into the FPGA chip plays a key role to realize a streaming DAQ system. The block diagram of the prototype streaming TDC is shown in Fig. 3. This firmware
consists of two blocks. One is the online data processing (ODP) block, which digitizes the timing of input
signals and proceeds some simple correction in parallel. The timings of the leading and the trailingedges of an input pulse are independently digitized with a least significant bit of 0.97 ns realized by
the 260 MHz multi-phase clock signals. The digitized data fragments are sent to a paring unit. The
unit provides a pair of the leading and the trailing edges from a set of data fragments, and calculates
time-over-threshold (TOT) in real time. A data word is defined for the timing to include the leading-edge
timing and TOT value. A time-walk of the leading edge timing coming from a different pulse height iscorrected online in the next block, the time-walk corrector unit. The correlation plot between the leadingedge timing and TOT for β rays from the 90 Sr source obtained for the prototype fiber tracker is shown in
Fig. 4 (a). Signals from the β rays are observed around a TDC value of 480 and some background events
are also found around 450. To save the memory for the look-up tables, this correlation is divided five48
TOT regions and then constant correction values are applied in each region instead of using a smoothfunction as shown Fig. 4 (b). The TOT ranges are determined so that the standard deviation of the raw
timings for the regions ranging from 1 to 4 are the same. The performance of this time walk corrector
is discussed in Sec. 6. Finally, the data word having a small TOT value is filtered out in the end of the
ODP block to reject noise signals.
The other built block is the vital block. Here, we introduce an important technique on the data
streaming, that is the heartbeat method. The streaming TDC is required to measure the timing forcharged particles randomly arriving on the target with a precision of 0.97 ns during a spill with a few
seconds. The dynamic range becomes in the order of 1010 and thus a long-bit-length counter is usuallynecessary. Therefore, the special data, heartbeat, periodically generated by the 16-bit local counter
presented as the heartbeat frame counter in Fig. 3 is introduced. By counting the number of heartbeats,
one can know the time from the beginning of beam extraction. The heartbeat data is inserted in theheartbeat unit after merging the data path from parallel to serial in the merging unit. Finally, the data
are transmitted by SiTCP to the server computer.

Fig.3. Block diagram of the streaming TDC implemented in the FPGA chip. The timings aremeasured for the leading and the trailing edges of an input pulse by the TDC unit. The
two timings are coupled and TOT is calculated in the pairing unit. A time-walk of theleading-edge timing by the time walk corrector unit. The data word having a small TOT
value is discarded by the TOT filter unit. The data path is merged from parallel to serial
in the data merging unit. The heartbeat data, which is generated by the heartbeat frame
counter, is inserted in the heartbeat unit.

§ 4. Test using high-rate beam at ELPH

A test was performed at Research Center for Electron Photon Science (ELPH), Tohoku University

in December 2018 to evaluate the detector performance at high rates and commission the prototype
streaming DAQ system.

49

Fig.4. (a) Correlation plot between the leading-edge timing and TOT obtained using β raysfrom a 90 Sr checking source. It should be noted that the direction of the vertical axis isreversed respect to that of in Fig 7. (b) Similar plot after the time walk is corrected in thetime-walk corrector unit. The vertical lines in (b) represent the TOT regions.

4.1 Setup
The experimental setup is placed near the BST ring in the second experimental hall at ELPH.
The detectors were set up as shown in Fig.5. A high-intensity bremsstrahlung photon beam [10] fromthe booster storage (BST) ring [11] was converted into electron-positron pairs at the exit window on
the flange of the vacuum duct and additional 1-mm-think aluminum-place converter. The timings arerecorded from the prototype fiber tracker, the time zero counter, the drift chamber, and timing-reference
counters. An analog signal for each detector is converted into the timing signal using the discriminator,
the NIM EASIROC module, and amp-shaper-discriminator (ASD). After that, all signals are digitized totime information by the prototype streaming TDC and transferred to the computer.
4.2 Experimental condition of the prototype fiber tracker
The experimental conditions for the prototype fiber tracker are four types of the beam rate (1.3
kHz/fiber, 50 kHz/fiber 500 kHz/fiber, and 1400 kHz/fiber) and three types of gain (40, 30, and 25 ) Here,for example, the condition described by a gain of 30 denotes that a photo-electron (p.e.) corresponds toan ADC value of 30. The set threshold value corresponded to 3.5 p.e.in the EASIROC chip.

§ 5. Analysis

5.1 Analytical method
We employed two types of analysis methods, namely the trigger-less analysis and the trigger analy-

sis. In the case of the trigger-less analysis, we analyze all the data of uncorrelated hits among detectors
by the streaming TDC. On the other hand, we find coincidence of the reference counters first, and build
an event with respect to it in the trigger-based analysis. The trigger analysis method are shown in Fig.6.
This figure shows the time and hits information represented by stars of the prototype fiber tracker andreference counter. When the time information of reference counter 1, 2, 3, and 4 coincides with a time

50

Fig.5. Experimental setup. The red line shows the electron-positron beam form the flange.
Those detectors were installed in the order of the reference counter 1, the time zero
counter, the reference counter 2, the reference counter 3, the fiber tracker, the reference counter 4 and the drift chamber (DC) form upstream of the beam. Arrows shows asignal flow. An analog signal form each detectors was discriminated by the discriminator,
the NIM EASIROC module, and ASD. After that, those signals were digitized to time
information by the prototype streaming TDC and transferred to the personal computer.

gate of about 45 ns, we recognize that an event was occurred. The prototype fiber tracker hits falling in
the timing range of ±40 ns respect to the reference counter 1 were collected and packed into the event
data set. In addition, the time-of-flight of the prototype fiber tracker was defined as the time dereference
from the reference counter 1.
5.2 Timing resolution
We used the trigger analysis. In order to correct time walk, we determined the correction function
using the data set with the low rate (1.3 kHz/fiber). The figure 7 (a) shows the correlation between TOF
and TOT before correction. This plot was fitted by a cubic function as shown in Fig.7 (a) by the redline. The fitting function was phenomenologically chosen in order to reproduce the coronation plot well.
The figure 7 (b) shows the correlation between TOF and TOT after correction. The fitting parameters
obtained from this data set were applied to the analysis for other data sets.
The rate dependence of the timing resolution was studied. It was obtained as the standard deviationof the corrected TOF peak by fitting a gaussian function. The timing resolution for a certain layer was
obtained as shown in Fig.8 as a function of the rate per fiber. The horizontal and the vertical axis
represent the timing resolution in sigma and the rate per fiber. Although the timing resolution of the
prototype fiber tracker deteriorates as the beam rate increases, the timing resolution of better than 1.0
ns is achieved at 1 MHz/fiber. The obtained timing resolution satisfies our requirement.

51

20

TOF[channel]

TOF [channel]

Fig.6. Trigger analysis. This figure shows the time and hit information of the prototype fiber
tracker and reference counter. The red line shows a time gate of about 45 ns. The yellow
line shows the timing range of ± 40 ns from the reference counter 1. The green line shows
the time difference from the reference counter1.

300

(a)

15
10

250

5

200

0

150

−5

100

−10
−15
−20
0

20

40

60

80

100

120

TOT [channel]

20

100

(b)

15
10

80

5

60

0
−5

40

−10

50

−15

0

−20
0

20

20

40

60

80

100

120

TOT[channel]

Fig.7. Time walk correction. The figure (a) shows the correlation between TOF and TOT before
correction. The red line shows the fitting function. The figure (b) shows the correlation
between TOF and TOT affter correction.

0Time resolution [ns]

52
2
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0

500

1000

1500

2000

2500

3000

Beam rate [kHz]Fig.8. Rate dependence of the timing resolution. The horizontal and vertical axis show thetiming resolution in sigma and the rate/fiber.

5.3 Detection efficiency
The detection efficiency at a high rate is evaluated as well as the time resolution by using the trigger
analysis. The detection efficiency of each layer was defined by using the equation (1).
ef f iciency =Ntarget layer
Nother 11 layers(1)

Where Nother 11 layers is the number of events when all the layers except for the target layer were
fired, and Ntarget layer was the number of events when the target layer was fired. We recognize that thelayer was fired when at least one hit remained after gating the TOF distribution with the 2.8 ns time
window corresponding to the 3σ of the timing resolution. The obtained detection efficiency of a certain
layer was shown in Fig.9. The markers with different colors represent the results from different gain

efficiency [%]conditions. The vertical axis show the beam rate per fiber. One can find that the detection efficiency was
100
99
98
97
96
95
94
93

gain25gain30
gain40

92
91
90
0

200

400

600

800

1000

1200

1400

Beam rate [kHz]Fig.9. Detection efficiency of the certain layer. The horizontal and vertical axis show the detection efficiency and rate/fiber, respectively. Black, blue and red points show the different
gain conditions.

decreased when the beam rate was increased.
We concluded that one reason for the decrease of the detection efficiency is the gain drop due to53
the over current in the EASIROC chip. The figure 10 shows the TOT distribution of one fiber when the
beam rate was increased. The histogram with different colors represent the results from different beam

countrate. Actually, the TOT peak of the distribution was shifted to the left hand side when the beam rate
200
180
160
140
120
rate 1.3kHz

100

rate 50kHz

80rate 500kHz

60

rate 1400kHz

40
20
0
0

20

40

60

80

100

120

TOT [channel]

Fig.10. TOT distribution. The different colors show the distribution of different beam rate.

was increases. In additiion, we concluded that another reason for the decrease of the detection efficiency
is the increased counting loss due to the signal pile-up in the EASIROC chip.
We studied the dead time of the EASIROC chip and the counting loss using the trigger-less analysis.
The time interval (∆T ) is defined as the timing difference of leading edges of two signals. The obtained

3000
2500

(a)

countscounts∆T distribution was shown in Fig.11.
3000
2500

2000

2000

1500

1500

1000

1000

500

500

0
0

1000 2000 3000 4000 5000 6000 7000 8000 900010000∆ T [ns]00(b)100 200 300 400 500 600 700 800 900 1000
∆ T [ns]

Fig.11. Distribution of ∆T . The figure (a) shows the distribution of ∆T in the range from 0 to
10000 ns. The figure (b) shows the distribution of ∆T in the range from 0 to 1000 ns.
The red line shows the fitting function.

The Fig.11 (a) and (b) ware the results from different range of the horizontal axis. In the range from0 to 100 ns in Fig.11 (b), this plot was fitted by a exponential function by the red line. The exponentialfunction representing the paralyzable model was chosen as the fitting function. In the range from 0 to
100 ns in Fig.11 (b), one can find that the counts decreases due to the counting loss. From this result,

54
the survival ratio is obtained, and is defined as follow.
Survival ratio = 1 −Scount loss
Sideal case(2)

where, Scount loss is the area of the counting loss. Sideal case is the area of the not counting loss
which was obtained by the fitting function. In order to evaluate the beam rate dependence of the survival
ratio, the beam rate was calculated as follow.
Beam rate =Observed rate
Survival ratio(3)

where, the observed rate is the counting rate actually observed.
The survival ratio for a certain layer was obtained as shown in Fig.12 as a function of the beam
rate per fiber. The horizontal and the vertical axis represent the survival ratio and the beam rate perfiber. One can find that the survival ratio decreases as the beam rate increases. In addition, one canfind that the counting loss is 5 % at the beam rate of 1 MHz/fiber. Furthermore, the correlation between
the observed rate and beam rate was shown Fig.13. The horizontal and the vertical axis represent theobserved rate and the beam rate. This plot was fitted by the the equation (4) which is the paralyzable
model function. As the fitting result, it was found that the dead time of EASIROC is about 48ns.
Ro = Rb · exp(−Rb · τ )(4)Observed rate [kHz]Sarvival ratio

where, Ro is the observed rate, Rb is the beam rate , and τ is the dead time.

1
0.95
0.9

3000
2500
2000
1500

0.85

1000

0.8

500

0.75

0

0.7
0

500

1000

1500

2000

2500

3000

500

1000

1500

2000

2500

3000

Beam rate [kHz]Beam rate [kHz]Fig.12. Survival ratio. The horizontal and vertical axis show the survival rate andthe beam rate.

Fig.13. Correlation between the obtained observed rate and beam rate was shown.
The horizontal and vertical axis show
the observed rate and the beam rate.
The paralyzable model function isshown by the black line.

§ 6. Performance of the ODP block

In this section, we describe the performances of the time walk corrector unit and the TOT filter

unit in the online data processing block of the streaming TDC. The motivation to introduce the time55
walk corrector is to reduce CPU load. When the process searches an event using timing coincidence
among detectors in the server computer, the coincidence gate width should be as narrow as possible. For
this purpose, the long tail structure due time walk seen in Fig. 4 (a) is undesirable. As the time walkcorrection can be performed in parallel for each channel, the correction was applied in FPGA instead of
CPU to reduce unnecessary CPU load. On the other hand, aim of the TOT filter is to reduce the data
size by rejecting dark noise of MPPC. In this analysis, the data set for the beam rate of 1.3 kHz/fiber wasused.
6.1 Time walk corrector
As we described in Sec. 3.3, the TDC values were corrected by constant values. Thus, it is difficult
to obtain the same timing resolution mentioned in Sec. 5. Here, we focus on the tail structure of the
TDC distribution. The TOF distributions of the prototype fiber tracker with and without the time walkcorrector are shown in Fig. 14 (a) and (b), respectively. In order to evaluate the length of the tail structure, we defined the timing width from the peak position of the distribution to the horizontal position
when the height becomes one thousandth. As shown in Fig. 14, the timing width when time walk was
not corrected was about 9.0 ns, however, it becomes shorter to about 6.0 ns. As the result, the time walkcorrector shows that it can make the timing distribution narrower, however, the small tail still exists.
The number of TOT regions and those intervals of dividing should be studied more.

Fig.14. (a) The TOF distribution without the time walk corrector. (b) The same distribution
with the time walk corrector. The vertical lines show the x position when the height ofthese distribution become one thousandth.

6.2 TOT filter
We report the detection efficiency and the data size when discarding data with TOT less than 30
by the TOT filter. As it is known that the dark noise contribution appear mainly below 30 ns in the
TOT disribution by the previous study [12], we set the filter threshold to 30. The obtained detection
efficiency is 99.82±0.6%, which is the same efficiency shown in the most left side in Fig. 9. Thus, loss
due to the TOT filter was quite small. On the other hand, we found that the fraction of the data rate
discarded by the TOT filter was 0.15 Mbps. It is clear that the contribution from dark noise to the data

56
size was also quite small. As we set the discriminator threshold in EASIROC to 3.5 p.e., the obtained
data reduction was reasonable because the pulse heights of dark noise were mainly single photo electron.
The effectiveness of the TOT filter seems to be small, however, we used MPPC that were not damagedby radiation in this experiment. In the future, the effectiveness of the filter for the radiation damaged
MPPC should be investigated.

§ 7. Conclusion

We are planning the high-statistic Λp scattering experiment to better understand the ΛN interac-tion. The layerd Λp scattering experiment will be conducted in the high-momentum beamline at J-PARC.
We developed the prototype fiber tracker in the high-momentum beamline. The prototype fiber tracker
consists of scintillating fibers with a diameter of 1 mm. Each fiber is connected to MPPC. The signal
from MPPC is read by the NIM EASIROC module. The timing signal from the NIM EASIROC module
is transferred to the prototype streaming TDC. In order to evaluate the performance at high rates, theprototype fiber tracker was tested by the ELPH facility. By using the trigger analysis, we found that the
prototype fiber tracker showed the timing resolution of better than 1.0 ns at 1 MHz/fiber. The obtained
timing resolution satisfies our requirement. However, the detection efficiency was decreased when the
beam rate was increased. We concluded that this reason the detection efficiency deteriorated is the gain
drop due to the over current and the increased counting loss due to the signal pile-up in the EASIROC
chip. By using the trigger-less analysis, it was found that the dead time of EASIROC chip is 48 ns with
5 % counting loss at 1 MHz/fiber. Therefore, in order to prevent the deteriorated detection efficiency athigh rate, we need new MPPC readout module with the dead time of 30 ns and the counting loss of 3 %in the future.

§ 8. Acknowledgements

We would like to acknowledge the outstanding efforts of ELPH. This work was supported by aGrant-in-Aid for Scientific Research(A) (Grants No.16H02188) from the Japan Society for the Promotionof Science.

References[1]

P.B. Demorest et al.: Natur 467 (2010) 1081.

[2]

J. Antoniadis et al.: Science 340 (2013) 1233232.

[3]

H. Noumi et al.: J-PARC E50 Proposal (2012).

[4]

Opto-Semiconductor Handbook, Hamamatsu Photonics K.K.

[5]

EASIROC developed by Omega/IN2P3/weeroc, http://omega.in2p3.fr/[6]Xilinx, https://www.xilinx.com

57
[7]

Y. Igarashi, M. Ikeno, M .Saito, K. Nakayoshi, M. Tanaka, T.N. Takahashi, M. Moritsu, A. Okamura, K. Hosomi, T. Takahashi, K. Itahashi, IEEE Trans. Nucl. Sci. vol. 57, Issue2, (2010), 618624.

[8]

T. Uchida, IEEE Trans. Nucl. Sci. vol. 55, (2008), 1631.

[9]M. Nakano, Timing distribution for the Belle II data aquisition system, JINST, 7 (2012) C01028.

[10] T. Ishikawa et al.: Nucl. Instrum. Meth. A622 (2010) 1.
[11] F. Hinode et al.: Proceedings of the 7th International Particle Accelerator Conference, IPAC2016(2016) 701.
[12] R. Honda, Doctoral thesis, http://lambda.phys.tohoku.ac.jp/d̃b/human resource/thesis/2005 B 3 D 1.pdf

58

ELPH Annual Report, Tohoku University (2018)(ELPH Experiment : #2900)

Development of a beam-timing detector for the
charmed-baryon spectroscopy experiment at J-PARC
T. Akaishi1 , T. Aramaki2 , H. Asano3 , C.-Y. Chang4 , W.-C. Chang4 , R. Honda2 ,Y. Igarashi5 , T. Ishikawa6 , S. Kajikawa2 , Y. Ma3 , K. Nagai4 , H. Noumi7,5 ,A. Sakaguchi1 , H. Sako8 , K. Shirotori7 , T.N. Takahashi7 ,and for the J-PARC E50 collaboration
1

Department of Physics, Osaka University, Toyonaka 560-0043, Japan2

Department of Physics, Tohoku University, Sendai 980-8578, Japan
3
4

5

Meson Science Laboratory, RIKEN, Wako, 351-0198, Japan

Institute of Physics, Academia Sinica, Taipei 11529, Taiwan

Institute of Particle and Nuclear Studies (IPNS), High Energy Accelerator Research
Organization (KEK), Tsukuba, 305-0801, Japan

6

Research Center for Electron Photon Science (ELPH), Tohoku University, Sendai, 982-0826,
Japan

7
8

Research Center for Nuclear Physics (RCNP), Osaka University, Ibaraki, 567-0047, Japan

Advanced Science Research Center (ASRC), Japan Atomic Energy Agency (JAEA), Ibaraki,319-1195, Japan

We have developed a beam-timing detector, which gives the time reference for all detectors, for the
charmed-baryon spectroscopy experiment at J-PARC. It uses a high-intensity secondary beam of 6.0 ×

107 /spill (30 MHz for the 2-s extraction) for sufficient yield of charmed baryons. The beam-timing de-tector has to be operated under a high-counting rate environment. The developed detector is comprisedof an X-shaped acrylic Cherenkov radiator and a photo sensor MPPC. To use in a high-counting rateenvironment, we have employed a narrow width (3-mm) for fine segmentation, and an amplifier forshaping signal into a narrow width (10 ns). We have tested a prototype of the beam-timing detector
using positrons and electrons converted from the high-intensity bremsstrahlung-photon beam at ELPH.
The typical time resolution is (54.0 ± 0.8) ps (σ) at an intensity of 2–3 MHz, which corresponds to the ex-pected intensity at J-PARC. The developed X-shaped Cherenkov counter can be used for the experimentat J-PARC. We have found the deterioration of the time resolution of the detector at high intensities, andinvestigated the effects of signal overlapping to the time resolution by analyzing the waveform data.

§ 1. Introduction

We plan to perform charmed-baryon spectroscopy (J-PARC E50 experiment [1]) at the high-momen-tum beamline of the hadron experimental facility at J-PARC. In the experiment, we produce excitedstates of charmed baryons via the p(π − , D ∗− )Yc∗+ reaction using π − beam of 20 GeV/c. We measure theproduction rates and decay branching ratios of the excited states in a wide mass region by a missing-

59
mass method. Diquark correlation can be revealed from the properties of the excited state of observed
charmed baryons. We need a detector system for measuring the arrival timing of a charged particle inthe beam on the experimental target. We use a high-intensity secondary beam as high as 6.0 × 107 /spill(30 MHz for the 2-s extraction) for sufficient yield of charmed baryons. The beam-timing detector has tobe operated under a high-counting rate environment. The time resolution of 60–80 ps (σ) is required to
identify a forward scattered particle from the target by Time-of-Flight with TOF counter in the spectrometer. The beam-timing detector is placed where the leakage flux of the magnetic field is not sufficiently
small at the entrance of magnet.

§ 2. Prototype of the beam-timing detector

We have developed a detector comprised an acrylic (PMMA: poly-methyl methacrylate so called

the acrylic resin) Cerenkov radiator with a cross section of 3×3 mm2 and a length of 150-mm and amulti-pixel photon counter (MPPC) (S13360-3050PE). The refractive index of PMMA is 1.49, going a
Cherenkov angle of 48 degrees for charged particles with β = 1. We used the directivity of the Cherenkov
light. And, we employed the mean time of the timing of the both side. We devised a X-shaped radiator.
It should be noted that this is cut out from an acrylic plate. We can cancel different travelling timesof Cherenkov photons to a photo sensor by reading from two directions and expect to improve the time
resolution by increasing the light output. This is a novel detector we developed. An I-shaped Cherenkov

45°

Fig.1.

Schematic view (left) and photo (right) of the X-shaped Cherenkov counter. The twoacrylic bars are connected each other at the center, and each of them are placed along 45
degrees close to the emission angle of the Cherenkov light from the high-energy pions.

counter is also tested for comparison, which consists of a single acrylic bar. These Cherenkov counters
are placed along 45 degrees close to the emission angle of the Cherenkov light. For a comparison, plastic

60
scintillation counter having a cross section of 3×3 mm2 and a length of 150-mm is also used with MPPC.
These three kinds of the prototype detectors are tested by using a high-intensity positron and electron(mixed) beam.

§ 3. Test experiment

The performance study of the prototype beam-timing detectors were carried out at the second pho-ton beamline in the second experimental hall at ELPH [2]. We used electrons and positrons as a beam
converted from the extracted bremsstrahlung-photon beam. The converter was the 1-mm thickness aluminum exit window in the flange of the vacuum duct, and an additional 1-mm thickness aluminum
plate. Detectors were installed at the downstream of the beam extraction points to the GeV-γ building.
Figure 2 shows the experimental setup. The prototype beam-timing detectors are placed between the

Cherenkov counter
Ref1

I-shaped

X-shaped

Ref2

Beam
e+/eMPPC + Amp
Fig.2.

Schematic view of the experimental setup. The prototype beam-timing detectors areplaced between the two timing reference detectors Ref 1(upstream) and Ref 2 (downstream). Each of Ref 1 and Ref 2 consists of a plastic scintillator of the size of 3 mm(W) ×
3 mm(T) × 150 mm(L) with MPPC.

two timing reference detectors Ref 1(upstream) and Ref 2 (downstream). To increase the beam intensity,
the beam extraction cycle was shortened from 10 s at normal operation to 4 s, and the higher intensity
was obtained than 2 MHz for a 3-mm segment. We gradually increased the counting rate by adjusting the beam current of the accelerator and evaluated the performance of the prototype at beam rate
up to 5 MHz. Since the intensity was not constant during the extraction period, the counting rate ofa detector was measured with the HUL scaler, which could provide the number of signal counts for a
200-ms interval corresponding to the event of interest. Figure 3 shows the rate distribution for the topof the X-shaped Cherenkov counter. We got the three different intensity conditions. Since the measured
rates were not constant in each condition, the events are divided into two rate groups. We evaluatedperformance of detectors at six counting rate regions as shown in Fig.3. We measured the timing of asignal from a prototype detector with two TDC modules, a DRS4 modules [3] and a HUL modules [4]61
implemented an FPGA-based high-resolution TDC. The DRS4 module can also get waveform of a input
signal. The obtained waveform was only used to determine the pulse height for the time-walk correction,and to analyze the pileup effects in the high-rate conditions. For Cherenkov counters, we used a PMT
AMP module for amplifying signals by 10 because pulse heights were low.

(1)

(2)

(3)

(a)

(4)

1

2

(b)

3

4

5

6

7

Rate [MHz]

(5)

1

(6)

2

3

4

(c)

5

6

7

Rate [MHz]Fig.3.

Counting rate distributions for the three different intensity conditions. The average rate
is 0.2, 1.5, and 3.0 MHz for a 3-mm segment for (a), (b), and (c), respectively. Since themeasured rates scatter in each condition, the events are divided into two rate groups.
The vertical lines show the boundary to separate the two groups. Finally, we get six
rate groups: (1)0.14–0.22 MHz, (2)0.22–0.30 MHz, (3)0.90–1.40 MHz, (4)1.40–2.00 MHz,(5)2.20–3.40 MHz and (6)3.40–5.00 MHz, respectively.

§ 4. Analysis

Figure 4 shows the pulse height distributions of the scintillation counter and the Cherenkov coun-ters. To obtain the time resolution for the minimum ionizing particles (MIPs), the events were selectedwith the pulse height of the MIPs as shown in the red region in Fig.4. Three independent time difference distributions were obtained from three timing signals, t1 coming from Ref 2, t2 , t3 from prototype
detectors. The pulse height dependence of timing was corrected by using the correlation between thetime difference of two counters and the pulse height information. For the correction of the scintillation
and Cherenkov counters,bf (V ) = a + √ + c ln (V )V

(1)Counts/3 mV

10000

Counts/3 mV

62

(a)

8000
6000

4000
3500

(b)

3000
2500
2000

4000

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500

0
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200

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2000
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0
0

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Pulse height [mV]Time difference [ns]Fig.4.

Fig.5.

1000 1200 1400
Pulse height [mV]Counts/3 mVCounts/3 mV

Pulse height [mV]

400

600

800

1000 1200 1400
Pulse height [mV]

Pulse-height distributions for the prototype detectors: the scintillation counter (a), the Ishaped Cherenkov detector (b), the top (c) and bottom (d) sides of the X-shaped Cherenkov
detector. It should be noted that signals are amplified by 10 for the Cherenkov counters.

(a)

(b)

Correlation between the measured time difference and pulse height for the top side of the
X-shaped Cherenkov counter (a). After applying the pulse-height time-walk correction(b), the constant timing is obtained independently of the pulse height.

were used, respectively, where ”V ” means pulse height. We used the maximum value of the timing
signal peak from the waveform obtained by DRS4 module as a pulse height. The formula (1) was applied
for the scintillation counter, and Eq. (1) with c = 0 was used for the Cherenkov counter. Figure 5
shows the correlation between the pulse height and the time difference before (a) and after (b) applying
the time-walk correction in the HUL module. The time difference ti − tj should have the resolution of
σi2 + σj2 , where σi and σj are resolutions of measured timings ti and tj , respectively. Therefore, thewidths of three timing difference distributions, t2 − t3 , t3 − t1 , and t1 − t2 , gave the timing resolutions

σ1 , σ2 and σ3 . The timing t2 of the prototype detector was given by the I-shaped Cherenkov counter.

63
The timing t3 of the prototype detector was given by the X-shaped Cherenkov counter. To give timingsof the plastic scintillator and the X-shaped Cherenkov counters, we employed the mean time of signals
from the both edge of a counter. Since we only measured the timing for a single edge for the I-shaped
Cherenkov counter, we were not able to employ the mean time. From three combinations of the timedifferences, the intrinsic time resolutions of each counter were obtained.

§ 5. Results

Figure 6 shows the time resolution as a function of the counting rate. The time resolution becomesworse for all the detectors as the counting rate increases. The time resolution of Cherenkov countersmeasured by both DRS4 and HUL modules are better than 80 ps (σ) at the counting rate of 2–3 MHz.
The time resolutions of the X-shaped Cherenkov counter at the expected counting rate of 2–3 MHz were(66.4 ± 0.9) ps (σ) and (54.0 ± 0.8) ps (σ) by the DRS4 and HUL modules, respectively.
(a)Fig.6.

(b)

Time resolution as a function of the counting rate for the prototype detectors by the DRS4
module (a) and the HUL module (b), respectively. The horizontal bars represent the rangeof the counting rate.

We considered the cause of the deterioration of the time resolution under the high-counting rateenvironment. We acquired the waveform information by the DRS4 module. Figure 7 shows an example
of an event that has a signal just before the trigger timing. The signal has small pulses following themain pulse. The effect of the pileup on ringing was investigated by removing the events on the ringing
region before the trigger timing signal. Several time windows of the removing region were selected as
50 ns, 100 ns, 150 ns and 200 ns. Figure 8 shows that the time resolution becomes better when thetime window becomes wider. As a result, we obtained the time resolution of (59.9 ± 1.8) ps and (39.6 ±1.9) ps by the DRS4 and the HUL modules, respectively. It was found that the ringing affects the time
resolution by deteriorating timings from the baseline changes. Optimization of the shaping circuit is
crucial to obtain a better time resolution.

64

Trigger Timing

RingingFig.7.

Example of an event that has a preceding signal before the trigger timing. The selectionof such an event is made by examining the presence of a preceding signal in the range ofthe red line.
(a)Fig.8.

(b)

Rate dependence of time resolution after removing the pileup events by the DRS4 module(a) and the HUL module (b), respectively. The horizontal bars show the range of thecounting rate by selecting event-by-event scaler counts.

§ 6. Conclusion

We tested prototype beam-timing counters by using a high-counting beams. The time resolutionsof the X-shaped Cherenkov counter at the expected counting rate of 2–3 MHz were (66.4 ± 0.9) ps(σ) and (54.0 ± 0.8) ps (σ) by the DRS4 and HUL modules, respectively. Therefore, we conclude that

the X-shaped Cherenkov counter which has the best time resolution provides the best as the beamtiming detector. In the development of the beam-timing detector for the J-PARC E50 experiment, thedevelopment of the detector component which fulfills the required performance was achieved by using
the X-shaped Cherenkov radiator and MPPC.
For the next step, we need to design the actual detector. For designing the actual detector, wehave to perform following things, (1) determination of an arrangement method of the X-shaped acrylic

65components, (2) time-walk correction without ADC, and (3) shaping circuit improvement for eliminating
the ringing effects. (1)When the X-shaped Cherenkov counter becomes the component of beam-timing
detector, it should be arranged as close together as possible in order to cover the beam region. (2)In thepresent study, we performed the time-walk correction using both timing and pulse height of a signal.
Since a streaming DAQ system without dead time is used, a normal ADC with a dead time of several µs
cannot be used in the charmed-baryon spectroscopy experiment. In addition, if a flash ADC is used, theamount of data becomes enormous and data transfer becomes difficult. For these reason, we have to use
a fast signal digitalization without ADC so that we consider to use the Time-over-Threshold method inwhich the signal width from both leading and trailing timings measured by TDC is used instead of ADC.
Since the shaping circuit is designed to shape signals to be narrow by using a simple differentiation
circuit, the width of the signal saturated and lost linearity with pulse height information when the pulse
height becomes high. It is not sufficient to correct the pulse height from the signals width. We should
improve the shaping circuit having the correlation between signal with and pulse height. (3)In order
to eliminate the effect of a ringing pileup in high-counting rate environments, we have to reduce theringing of the shaping circuit. The ringing suppressed by finely adjusting circuit elements such as thetime constant, multiplication factor, and the damping resistance of the shaping circuit. We will solvethese problems and plan to produce a beam-timing detector in the future.

Acknowledgments
Thanks to three test experiments in #2858, #2870 and #2900, we have succeeded in developing thebeam-timing detector. We would like to acknowledge the outstanding efforts of the staff at ELPH. This
work was supported in part by a Grant-in-Aid for Scientific Research(A) (Grants No.16H02188) from theJapan Society for the Promotion of Science.

References[1]

H. Noumi et al.: J-PARC E50 Proposal (2012).

[2]

T. Ishikawa et al.: Nucl. Instrum. Meth. A 622 (2010) 1.

[3]

T.N. Tomonori et al.: RCNP Annual Report 2016 ”Development of a FPGA-based high resolution
TDC using Xilinx Spartan-6”[4]

R. Honda et al.: http://openit.kek.jp/project/HUL

66

ELPH Annual Report, Tohoku University (2018)(ELPH Experiment : #2905)

Test of Detectors and Trigger System for J-PARC E16
Experiment using Positron Beam
M. Naruki1 , S. Ashikaga1 , R. Fujii1 , M. Ichikawa1 , K.N. Suzuki1 , K. Aoki2 ,K. Ozawa2,3 , T.N. Murakami3 , T.N. Takahashi4 , and S. Yokkaichi4
12Department of Physics, Kyoto University, Kyoto, 606-8502

IPNS, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki
305-080134Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113

Nishina Center for Accelerator-Based Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198
5

Research Center for Nuclear Physics (RCNP), Osaka University, 10-1, Mihogaoka Ibaraki,
Suita-shi, Osaka 567-0047

Performances of detectors together with integrated trigger system for the J-PARC E16 experiment
have been evaluated using the positron beam at ELPH. A read-out system of the Hadron Blind Detector(HBD) was newly developed for the experiment. The HBD signal for trigger decision is read-out directlyfrom the GEM, Gas Electron Multiplier of HBD. To optimize the trigger tile segmentation of HBD,
we have studied trigger efﬁciencies with the developed system for a variety of input charge. Also theintegrated trigger system and the effect of shower leakage of lead-glass calorimeter were studied.

§ 1. Introduction

The J-PARC E16 experiment aims at studying hadron mass in nuclear matter [1]. The mass of

vector meson is a key probe which is able to be directly related to the QCD condensate through the QCD
sum rule [2]. Di-lepton is an excellent probe to measure spectral information of vector meson, since it isalmost free from the ﬁnal state interaction. We plan to measure di-electron spectra produced in 30 GeV
p + A reactions at J-PARC high-momentum beamline. It is highly important for the measurement todevelop PID detectors having capabilities of coping with high interaction rate of 10 MHz. Also thetrigger performance is quite important to suppress huge hadronic background mainly originates frompions. In the test experiment at ELPH performed in Autumn 2018, we studied the trigger system of
Hadron Blind Detector (HBD), the integrated trigger system and an effect of shower development inseveral segments of lead-glass calorimeter.

§ 2. Experimental Setup

Figure 1 shows an experimental setup. As tracking devices, three sizes of GEM tracker will be usedin the coming experiment at J-PARC. The largest GEM tracker, named as GTR3, has an active area of
30 × 30 cm2 and used to generate a trigger signal. A plate of GTR3 was located at a most upstream side,
as in the J-PARC experiment.

67

Fig.1. Experimental Setup

In the middle of the setup, the test chamber for the HBD read-out system is located. The HBD isan electron identiﬁcation detector originally developed by PHENIX collaboration. It is a Cherenkov typedetector with three layers of GEM for gas ampliﬁcation. Whereas the detector signal is read out on a padplane, the signal for trigger is independently read out from the third GEM to join in the trigger decision
making. The new ASD read-out board has been developed for the E16 experiment to make a hit signal
for trigger decision. Since an efﬁciency of making the signal depends on the detector capacitance, theperformance has been tested using positrons for several possible capacitances.
In the most downstream side, blocks of lead-glass calorimeter (LG) was placed. It is used for electron identiﬁcation in a combination of the HBD. The basic performance of LG was studied in the past
test experiments performed at ELPH. The development of electric-magnetic shower in two segments ofcalorimeter was studied this time.

§ 3. Results

Figure 2 shows the performance of new read-out system of HBD with the detector capacitance of

1.8 nF. The signal level was 134 mV compared with the noise level of 20 mV in one-standard deviation.
The required performance of the ASD board is obtained as the efﬁciency of 99.9% for the input charge of
20 fC. We also evaluated the efﬁciency with the capacitance of 5.4 nF. In that case, the read-out system
can not fulﬁll the required performance due to the relatively low S/N of 3. The noise level stayed always
at 20 mV, however the signal was reduced to 80 mV due to the small capacitance. It is concluded thatthe trigger tile segmentation of HBD is able to be optimized if the read-out of a GEM foil is divided into
27 tiles, which corresponds to the one-tile capacitance of 2 nF.
Two blocks of lead-glass calorimeter are exposed to the 0.4 GeV/c positron beam to examine theshower development in adjacent segments of calorimeter. Especially the performance has been evaluatedon condition that the beam hits the boundary of two blocks. They are arranged as they are in the J-PARC
experiment as shown in the top right corner of Fig. 3. The clear anti-correlation has been observed to68

Fig.2. (left) Charge distribution read out from third GEM of HBD. The blue histogram is thecalibrated analog output of ASD read-out board, red histogram shows the charge distribution when the digital output of ASD ﬁres. (right) Input charge dependence of trigger
efﬁciency. Both plots are taken from [3].
demonstrate that all energy deposit of a single electron/positron can be measured with clustering oflead-glass segments.

Fig.3. Correlation between two segments of lead-glass calorimeter

The integrated test of the trigger system for the J-PARC E16 experiment was carried out. In the experiment, three types of detectors, GEM tracking detectors (GTR), HBD and LG are used for generating
triggers. The trigger system consist of four types modules. Trigger merging modules (TRG-MRG) receive
discriminated output signals from detectors and detect the leading edges. The timing information of theedges are transmitted to the trigger decision module (Belle2 UT3) with Aurora protocol. The trigger
signal generated with UT3 is distributed to frontend modules using B2TT protocol, through the trigger
distribution modules (Belle2 FTSW and RPV260). The performance of the trigger system with all types
detectors was evaluated with the positron beam for the ﬁrst time. In the test experiment, we used three69
detectors of GEM for GTR, GEM for HBD, and LG as a module of detectors. The DRS4 module wasused as a frontend module for LG. As the trigger system, four modules, TRG-MRG, Belle2 UT3, Belle2
FTSW and RPV260 were used. The trigger decision making was performed with the coincidence of threedetectors and distributed to the DRS4 ADC/TDC. The timing histogram between a hit information of LG
and the trigger signal received with RPV260 is indicated in Fig. 4. The enough performance of the time
walk of the trigger system is obtained to be 8 ns in the positron beam experiment.

[ns]

900
800
700
600
500
400
300
200
100
0

trigTdc {trigCh==1}
EntriesMean
Std Dev

h7

3627
794.4
1.488

[ns]
760 780 800 820 840 860 880 900 920 940
Fig.4. Trigger decision time

Acknowledgment
The authors would like to thank the J-PARC E16 collaboration for their direct and/or indirect assistance. We also would like to express our gratitude to staff members of ELPH for their support. We
thank to the KEK electronics system group for their help in developing of the ASD for HBD. This project
was supported by the RIKEN SPDR program, Grant-in-Aid for JSPS Fellows 18J20494, and MEXT/JSPS
KAKENHI Grant numbers 19654036, 19340075, 21105004, 20360670, 15H05449, 15K17669 and 18H05235.

References[1]

S. Yokkaichi et al. : proposal, http://j-parc.jp/researcher/Hadron/en/pac 1707/pdf/E16 2017-10.pdf[2]

P. Gubler and W. Weise: Phys. Lett. B751 (2015) 396-401.

[3]

K.N. Suzuki, Master Thesis, Kyoto Univ. 2019

70

ELPH Annual Report, Tohoku University (2018)(ELPH Experiment : #2911)

Performance Evaluation of a Fine-Grained Scintillator
Tracker for the T2K Near Detector Upgrade Project
Konosuke Iwamoto1 , Ryo Fujita1 , Kohei Matsushita1 , Masashi Yokoyama1 ,Tsunayuki Matsubara2 , Soichito Kuribayashi3 , Tatsuya Kikawa3 ,Takuji Arihara4 , and Yuito Awataguchi4
1
2

Department of Physics, University of Tokyo, Tokyo, 113-0033

Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization(KEK), Tsukuba, 305-0801
3
4

Department of Physics, Kyoto University, Kyoto, 606-8502

Department of Physics, Tokyo Metropolitan University, Tokyo, 192-0397

The T2K Near Detector ND280 Upgrade project is proposed to reduce the systematic uncertainties
of neutrino oscillation measurement from neutrino cross section that can be constrained by the neardetector measurement. One of the new detectors introduced in this project is called Super-Fine-Grained
Detector (SuperFGD), which consists of 1 × 1 × 1cm3 plastic scintillator cubes stacked to form a volumeof 192 × 56 × 184 cm3 in width, height, and length, respectively. The scintillator cube production method

has recently switched from extrusion method to injection molding method for mass production, andthe detector assembly utilizing the ultrasonic welding technique is under consideration. Beam test is
performed at ELPH positron beamline to evaluate the cube position dependence of the measurement,
cube-cube crosstalk rate, and the effect on the detector performance due to the ultrasonic welding on thecube.

§ 1. Introduction

T2K [1] is planning to extend its physics run until 2027 to achieve the statistics of 20 × 1021 protons

on target with upgraded J-PARC beam intensity. While this statistics allows the T2K neutrino oscillation
analysis to reach > 3σ sensitivity to charge parity violation in lepton sector, improvement in the total
systematic uncertainties from ∼ 6% to the level of 4% enables to achieve the > 3σ sensitivity withless statistics therefore earlier than the expected run period. In order to accomplish such goal, ND280
Upgrade proposes to implement new upstream trackers to improve the wide angle acceptance and low
momentum threshold [2].
One of the novel technologies introduced in ND280 Upgrade is SuperFGD [3]. It consists of 1 × 1 ×

1 × cm3 plastic scintillator cubes produced at UNIPLAST Co. (Vladimir, Russia) with reflector surface

obtained by chemical etching [4]. The full-size SuperFGD detector is comprised of 192 × 56 × 184 scin-tillator cubes, as shown in Figure 1, with the active mass of ∼ 2 tons. The 1 mm φ Wavelength Shifting(WLS) fibers are inserted along 1.5 mm φ holes in each side of the cubes to readout the scintillation light71
from three views by Multi-Pixel Photo-Counters (MPPCs). The first prototype cubes are produced by
extrusion method, and SuperFGD mass production method with injection molding process is establishedby INR RAS, Russia.

Fig.1.

Schematic concept of the SuperFGD structure. The full-size detector consists of 192, 56,
and 184 cubes in width, height, and length, respectively. The single cube size is designed
to be 1 × 1 × 1 cm3 . The green cylinders indicate the wavelength shifting fibers.

One of the major concerns of the full-size SuperFGD assembly is a method to control gaps between
the cubes to pass through the WLS fibers. During the manufacturing process, we expect fluctuations
in cube size and hole positions, and considering the fiber insertion through the longest sides with 192
cubes, we expect the maximum hole position tolerance of ±250 µm per cube. In order to obtain thealignments between the cubes, two assembly procedures are under research and development. One of
the methods is named ”fishing-line” method, which utilizes 1.3 mm φ flexible, plastic fishing-lines toalign the cube hole positions in three dimensions. After the 3D assembly of the cubes with fishing-lines,
each thread will be replaced by the WLS fibers to form the full-size detector. An another approach of the
full-size assembly is called the ultrasonic welding method. Instead of controlling the gaps by aligning
the hole positions, this method aligns cube positions to allow fiber insertion without cube displacements
by attaching the cubes on the polystyrene sheets by ultrasonic welding machine. The welding positions
and gaps between the cubes on the polystyrene sheets are carefully controlled by the equipments.
There are several validations need to be performed to progress with the cube assembly development.
First, the comparison of the performance between different cube production methods, extrusion andinjection molding, needs to be done to ensure that the change in the cube manufacturing method is
acceptable for the mass production. Also, the effect on the light yield measurement due to the ultrasonicwelding assembly needs to be evaluated. Since the ultrasonic welding method melts the surface of the
cubes to attach to the polystyrene sheets, possible loss of the light yield due to the leakage from thewelded surface is concerned.

72§ 2. Performance Evaluation with a Positron Beam

The beam test is performed at the research center for ELectron PHoton science (ELPH), Tohoku

University, to evaluate the performance of the SuperFGD cubes. Namely, the test focused on the measurement of the position dependence in single scintillator cube, validation of the ultrasonic welding
method with the optical crosstalk and light yield, and response comparison between the extruded andinjected cubes. The 500 MeV/c positron beam is used throughout the measurement performed at the
GeV-γ irradiation room. The schematic of the beam test setup is shown in Figure 2.

Fig.2.

Setup of the ELPH beam test for SuperFGD measurement.

The setup utilizes upstream and downstream hodoscopes to track the incident positron direction
and its hit position within the detector located in between them. Each hodoscope consists of pairs of
sixteen, aligned 1.5 × 1.5 mm2 cross-section polystyrene scintillating fibers stacked perpendicular toeach other. The total overlapped hodoscope area is 26 × 26 mm2 with 64 channels, and the position of

the track is determined by the area which two perpendicular scintillating fibers overlap to form a ”cell.”Event selection is performed by choosing events with hits in the given upstream and corresponding
downstream cells with greater than 2.5 photo-electron (p.e.) counts in both scintillating fibers, which
is defined as ”good” events. Among the good events, if the cubes are present in the corresponding cells,
Landau fit is performed on the light yield distributions obtained by each channel of the hodoscopes to use
the most probable values as the observed light yield in that channel. The diagram of the event selection
with two hodoscopes is shown in Figure 3.
There are three major detector setups used to perform the desired measurements on the cube performance, as shown in Figures 4-7. The single-cube setup focuses on the measurement of the position
dependence of the scintillator response and the performance comparison between the extruded and injected cubes. The light yield measurement with polystyrene sheets welded to the extruded cubes are
performed to evaluate the effect on the light yield. Two different thicknesses of 100 µm and 200 µm
sheets are used in this study, and separate measurements are performed in cases where the sheet is73

Fig.3.

The hodoscope configuration. Events are defined as ”good” events when there are hits
in the given upstream and corresponding downstream cells with greater than 2.5 p.e. inboth scintillating fibers.

parallel or perpendicular to the beam direction. In each measurement the cube is placed in the center ofthe beamline. The two-cube setup uses the extruded cubes to measure the optical crosstalk rate. One of
the cubes is located in the center of the beamline to measure the optical crosstalk to the other cube; thecubes with welded sheets are tested in this setup as well. The nine-cube setup has a 3×3 arrangement of
the cubes with the center cube located in the beamline. The optical crosstalk rate to the adjacent cubes
are measured and compared between extruded and injected cubes. In each setup, the measurements are
performed to obtain at least 300 good events for each cell to obtain sufficient statistics with less than 5%
uncertainty. The detailed explanation of the setup is available in [5].

Fig.5.
Fig.4.

The single-cube setup with the welded
sheet parallel to the beamline.

Fig.6.

The two-cube setup with welded sheets.

The single-cube setup with the welded
sheet perpendicular to the beamline.

Fig.7.

The nine-cube setup.

Figure 8 shows the position dependence of the observed light yield in the single cube obtained

74
from X, Y, and Z readout fibers, which the channels pass through the side, top to bottom, and along thebeamline, respectively. The observed light yield in the X, Y, and Z readouts is 28.7 p.e., 25.4 p.e., and 29.6
p.e., respectively. The measured light yield difference is not observed between the extruded and injectedcubes. Based on the event selection via cell readouts, we observe that there is a tendency that less lightyield is observed at cells which are far from the corresponding fiber readouts. It is suggested that the
non-uniformity of the light yield is due to the dependence of the acceptance of the scintillation light andthe fiber position. The cross-check with the SuperFGD optical simulation is ongoing to understand thisphenomenon.

Fig.8.

Average light yield of SuperFGD cube obtained in each cell. The left, middle, and right
distributions show the cube light yield measurements obtained from X, Y, and Z fiber
readouts, respectively. The white, dotted lines show the fiber hole and cub positions.

The light yield measurement with welded polystyrene sheets is summarized in Table 1. The total
light yield measured from X, Y, and Z fiber readouts is shown with different welding configurations. As
shown in the table, the configuration with welded sheet obtained 5-10% greater light yield measurement
than the cube without the welding. This result suggests that the effect of increased reflection withthe welded sheet is more significant than the welding iself causing the possible light leakage from thereflector region. The degradation of the cube performance is not observed in this measurement.
Configurations
No welding
With 100 µm sheet (horizontal)
With 200 µm sheet (horizontal)
With 100 µm sheet (vertical)
With 200 µm sheet (vertical)

Total light yield (X+Y+Z) [p.e.]
81.8
86.7
86.9
89.5
86.2

Table 1. Observed total light yield from X, Y, and Z readout fibers with different configuration for
the welded sheet, one-cube samples.
The crosstalk probability is measured using the two-cube setup with and without the ultrasonicwelding. The events are selected when there are hits in one of the cubes which is in the beamline; thelight yield ratio between the adjacent cube and the cube in the beamline is measured. The averagevalues of the light yield ratios are obtained separately for Y and Z readouts, and the crosstalk rates are75summarized in Table 2. The crosstalk rates are compared with the measurement obtained without thewelded sheets, and the decrease in the crosstalk probability by approximately 30% is observed for the
sample with welded sheets.
Configurations
No welding
With 100 µm sheet
With 200 µm sheet

Y readout fiber crosstalk rate [%]
2.9
2.2
2.5

Z readout fiber crosstalk rate[%]
3.0
2.1
2.0

Table 2. Crosstalk rate obtained from two-cube measurement with three different configurationsof welded sheets.
The crosstalk probability comparison between the injected and welded cubes are performed with
the nine-cube setup. Similar to the two-cube measurement, the light yield ratios between one of theadjacent cubes and the center cube are calculated for X, Y, and Z readout fibers. The cross talk probability
measurements for nine-cube setup with extruded and injected cubes are summarized in Table 3 and 4,
respectively. The average crosstalk rate for the Z readout fibers are 4.3% are and 3.6% for the extruded
and injected cubes, respectively. As the result, approximately 20% crosstalk rate reduction is observed
from the extruded to injected cubes. The position dependence of the light yield in nine-cube setup ineach readout direction is under investigation.
3.1(X Center)
4.4
Crosstalk rate [%]

1.9
4.5
3.3
3.8

4.4
(Z Center)
4.3(Y Center)

2.6(X Center)
4.3
Crosstalk rate [%]

2.1
4.0
3.4
3.4

Table 3. Crosstalk rate obtained from nie-cube
measurement with extruded cubes.

1.4
3.5
3.7
2.9

3.6
(Z Center)
3.8(Y Center)

1.6
3.5
1.3
2.8

Table 4. Crosstalk rate obtained from nie-cube
measurement with injected cubes.

§ 3. Summary

T2K is preparing for the extended physics runs to achieve > 3σ sensitivity to CP violation. ND280

Upgrade plans to implement new upstream trackers to obtain wide angle acceptance and low momentum measurement by near detectors to reduce systematic uncertainties in the oscillation analysis, andSuperFGD is one of the major components of the improvement. In order to ensure the feasibility of
the new cube manufactering process and assembly method, positron beam test is performed at ELPH
GeV-γ irradiation area. The measurements suggest no degradation of the cube quality by the injection
molding production method in terms of light yield or crosstalk probability, and the measurements withthe welded sheets show that the light yield reduction or increase in the crosstalk probability are notobserved with the assembly method. Further analyses of the beam test measurement to implement the
cube response in the detector simulation is in progress.

76

Acknowledgment
The authors express many thanks to the ELPH accelerator staff for the opportunity to perform thepositron beam test, especially Manabu Miyabe for the great support and coordination. The authors are
deeply grateful to Yury Kudenko from INR for the donation of the scintillator cubes and Davide Sgalaberna from CERN for the preparation of the WLS fiber optical interfaces which enabled this measurement and analyses. This work was published as the master’s thesis of Ryo Fujita from the University ofTokyo. This work was supported by Grant-in-Aid for Specially Promoted Research (16H06288).

References[1]

K. Abe, et. al., The T2K Experiment, Nucl. Instrum. Meth. A 659 106.

[2]

A. Blondel, et. al., The T2K-ND280 upgrade proposal, CERN-SPSC-2018-001. SPSC-P-357.

[3]

A.

Blondel,

et.

al.,

A

fully-active

fine-grained

detector

with

three

readout

views,

2018 JINST 13 P02006.
[4]

Y. Kudenko et. al., Extruded plastic counters with WLS fiber readout, Nucl. Instrum. Meth., A 469(2001) 340. https://doi.org/10.1016/S0168-9002(01)00780-X.

[5]

R. Fujita, Research and development of a new fine-grained scintillator tracker for the upgrade ofT2K near detector, Department of Physics, University of Tokyo Masters Thesis.

ELPH Annual Report, Tohoku University (2018)77(ELPH Experiment : #2913)

Evaluation of number of photon from small aerogel
Cherenkov counter
Kazuki Okuyama1 and Masashi Kaneta1 for the NKS2 collaboration
1

Department of Physics, Tohoku University, Sendai, 980-8578

We are developing an aerogel counter as an electron/positron veto counter in the NKS2 experiment.
The e− /e+ are produced by the photon conversion and it is necessary to reject them in trigger level forthe higher beam rate experiment in NKS2. We chose the aerogel of index 1.01 and tested whether we
can detect enough Cherenkov photons as the veto counter.

§ 1. Introduction

We are planing the Λn interaction measurement via final-state-interaction in γ + d reaction. We

would like to higher beam rate than current NKS2 experiment. The electron/positron veto counter isnecessary to carry the experiment out with keeping the high DAQ efficiency.
We adopted silica aerogel (index n = 1.01) to separate electron/positron and pion and veto thee− /e+ in trigger level. The veto counter was expected to locate between two drift chambers in themagnetic field. The size of aerogel was estimated as 30D × 60W × 40H [mm3 ].

We would like to use SiPM (MPPC) as the photon sensor in the magnetic filed to measure thecherenkov photon. Before using the MPPC, we measured number of Cherenkov photon from the aerogel
using 2-inch Photo-Multiplier Tube (PMT).

§ 2. Pre-test using cosmic-ray

We started the test using comsic-ray to check whether we can see the Cherenkov photons. Figure 1

shows the setup. We used the aerogel provided from Japan Fine Ceramic Center (JFCC).
Trigger of the data taking was made with the coincidence of three counters. To identify the muon
which has enough speed (β > 1/1.01) to make the Cherenkov photon in the aerogel, we stacked Pb
blocks as 50-cm height. Aerogel was covered with a Teflon sheet as a reflective material and black paper
as a light shielding material.
We used CAEN V792 QDC module and V775 TDC module for pulse charge and timing measurement, respectively. The DAQ program we used was UNIDAQ system [1].
The pedestal calibration for QDC module was done by random clock trigger. The one photo-electron
peak was found the data with self trigger of PMT that was connected to the aerogel. The peak position
for the one photo-electron was used to compute the number of photo-electron distribution later.

78

Setup of cosmic-ray test.

Number of Photo-electrons (H1949)

Fig.1.

Number of Photo-electrons (H7195)

Fig.2.

Distribution of the number photo-electrons with summing photo-electrons measured bothside of PMTs is shown in the left-hand side. The right hand-side figure shows the correlation of number of photo-electrons left- and right-hand side PMT.

The length of plastic scintillator part of the third trigger counter (located after Pb blocks) was about
60 cm. We select hits on center part from time difference of both side of PMTs. In order to guarantee thatit has passed through the middle, he center region was selected from the time-difference distribution of
the left and right PMTs.
Figure 2 shows the number of photon distributions from the cosmic-ray test. we took about 1 week
for the data taking.
The left-hand side plot is the sum of both side of number of photo-electron peak. The curve in theplot is the result of fitting of Poisson distribution with convolution of a resolution. The fitting result of
number of photo-electron was 8.2 and it was consistent with the estimation value 8.3 that was considered79
geometrical acceptance and the quantum efficiency of PMTs.
We can see the anti-correlation of number of photo-electrons in the two PMT signals (right-handplot in Fig. 2. In the plot, we can also see the relationship that when more light reaches one PMT, theother decreases. This setup uses different PMTs for the left and right PMTs, but the plot also shows that
Cherenkov light can be observed correctly.

§ 3. Beam test at the 2nd experimental hall

The results used in cosmic ray measurements were data collected for about a week. With beam test,

statistics can be accumulated in less time. The purpose here was to verify that the JFCC aerogel used
for cosmic ray measurements could obtain equivalent results using the beam. It was also to measure
and compare aerogels with the same refractive index of 1.01 made at Chiba University and JFCC.
The test was done at the downstream of NKS2 spectrometer in the 2nd experimental hall at ELPH.
Figure 3 shows the alignment of trigger counters and aerogel counters. The trigger counters were thesame with cosmic-ray test. The first trigger counter was an active target to make the electron/positronconversion from photon beam.
The data taking was done as a part of the other experiment (ELPH Experiment: #2878). The
trigger for data taking was made by that setup and our trigger counter hit information was used inoffline analysis.

Trigger counters

ton
Pho
beam

Aerogels

Fig.3.

Alignment of counters for the beam test. From upstream of photon beam, we set thetrigger counter 1, two aerogel counters, and trigger counter 2.

80

JFCC

Fig.4.

Chiba Univ.

Distribution of the number photo-electrons (NPE) with summing photo-electrons measured both side of PMTs. The left- and right-hand side plot are the distibution of NPEfrom aerogel provided from JFCC and Chiba University, respectively.

The data we recorded had included not only one charged particle events. We chose candidates ofthe one charged particle event by selecting in a region on scatter plot of pulse height from both trigger
counters. The number of photo-electron distributions are shown in Fig. 4. The pedestal and one photoelectron peak calibrations were done by the same method with cosmic-ray test.
The curve in the plots are the results of fitting by Poisson distribution convoluted the resolution.
We saw the similar NPE value from the both aerogels.
Note that the detail description of analysis is shown in Ref. [2].

§ 4. Summary

We tested the n = 1.01 aerogel whether we could measure enough Cherenkov photons for theelectron/positron veto counter. The cosmic-ray and the beam test showed about 7 to 8 photo-electrons byusing 2-inch PMTs. We are planning to use SiPM (MPPC), which is a semiconductor photo-detector, and
MPPC has a higher photo-detection efficiency (PDE) than PMT. Considering the efficiecy, it is expectedthat about 20 photons will be detected. We conclude that the aerogel of index 1.01 can be used as theelectron veto counter.

Acknowledgment
We thanks the accelerator staff of ELPH to provide the stable operation of accelerator.

References[1]

http://www-online.kek.jp/ online/Unidaq/default.htm[2]

Kazuki Okuyama, 2019, Bachelor thesis “Development of a compact airgel Cherenkov counter with
MPPC” (written in Japanese).

ELPH Annual Report, Tohoku University (2018)81

New Drift Chamber for an electron spectrometer at SCRIT
electron scattering facility
K. Tsukada1 , S. Takayama1 , and H. Wauke1
1

Research Center for Electron Photon Science, Tohoku University, Sendai, 982-0826

A new drift chamber was installed on the electron spectrometer at the SCRIT electron scattering
facility in November 2018, which enables us to reconstruct trajectories of scattered electrons precisely,and study both horizontal and vertical angular dependence of performances of the spectrometer. The
spacial resolutions and plane efficienies were studied by electron scattering data with the carbon target.
Vertical position resolution of typically 150 µm, and efficiency of almost 98 % were achieved. Further
analysis is still ongoing.

§ 1. Introduction

The SCRIT (Self-Confining Radioactive Isotope Target) [1] electron scattering facility have been con-structed at RIKEN to realize electron scattering off unstable nuclei as reported in previous reports [2–4].
Commissioning studies of spectrometers (WiSES : Window-frame Spectrometer for Electron Scattering,LMon : Luminosity Monitor) and target ion generation and transportation systems (ERIS : electronbeam driven RI separator for SCRIT [7], FRAC : fringing-RF-field-activated ion beam compressor [8])with several stable targets were already performed [5, 6]. In order to realize the experiment with unstable nuclear target, improvements of target preparation systems to achieve much higher luminosity
have been conducted. The performance of WiSES will be also updated by introducing a new drift chamber and measuring the three-dimentional magnetic field map because it was found that the momentum
resolutions of WiSES were worse than design values at the commissioning experiments. In this report,
the design and some result of the performance study of the new drift chamber is reported.

§ 2. WiSES and new drift chamber

The WiSES consists of a dipole magnet, two drift chambers, trigger scintillation counters and ahelium filled bag install between two drift chambers. Drift chambers are set in front of the magnet(FDC) and at the rear of the magnet (RDC) to reconstruct trajectories of scattered electons. Although
RDC has vertical and tilted wire to reconstruct electron’s trajectories three-dimentionally, original FDC
had only vertical wires and is sensitive to only horizontal information of trajectories. Details are reported elsewhere [3]. Figure 1 shows momentum resolutions which are defined as width of the elastic
peaks for some electron beam energies. The experimental results are obviously not explained by a simulation which is a Monte Carlo simulation with Geant4 toolkit and includes all materials and realistic

82
detector performances of WiSES. To achieve a good signal to noise ratio, and evaluate an acceptanceof the spectrometer accurately, a reason of the discrepancies should be identified. A new drift chamber(FDC2) which has both vertical and horizontal wires to reconstruct the three-dimentional information ofelectron’s trajectory was made and installed in order to study the reason and improve the spectrometer∆P/P [×10-3]

performances.
4

Experiment

3.5

Simulation

3
2.5
2
1.5

Fig.1.

150

200

250

300
Ee [MeV]

Reconstructed momentum resolutions evaluated from elastic electron scattering datawith a carbon target. The width of the peaks were fitted by a gaussain distribution.

Figure 2 is a picture of the FDC2 installed on WiSES. Geometrical parameters of FDC2 are listed
in Table 1.

Fig.2.

FDC2 installed on WiSES. The spectrometer are moved away from the target for a maintenance.

§ 3. Performance study

Figure 3 shows normalized counting rate taken by changing the high voltage supplied on field wires

and the threshold on the RAINER card. The electron source is a 90 Sr put on the side of FDC2. It is foundthat the plateau region appear around 2200 to 2300 V.
In December 2018, the electron scattering experiment with carbon targets were performed to study
the spectrometer performances. Figure 4 shows a drift time spectrum for hits belonging to a reconstructed track. Because the gas is a mixture of helium (80%) and isobutane (20%), the drift velocity

83

Table 1. Geometrical and operation parameters of new drift chamber (FDC2)

Layer configuration
Cell type
Cell size (side length)
Sense wire
Field/Shield wire
Number of channels#hit/#trig

Detector size
Effective area
Window
Operation gas
High voltage
Readout

1.5

FDC2
X-X’ Y-Y’ X-X’ Y-Y’Hexagonal
10 mm
Au-W, 30 µmφ
Au-Al, 80 µmφ
64 ch/layer for each X and X’
13 ch/layer for each Y and Y’1370(w)×430(h)×352(l) mm
1117(w)×234(h) mm
aluminized mylar, 25 µm
He+C2 H6 (80:20)
2320 V (X), 2230 V (Y)32CH RAINER

Vth=600mV
Vth=500mV

400

Vth=400mV

1

Vth=350mV

300
200

0.5

100
0
1800

Fig.3.

1900

2000

2100

2200

0
-100

2300
HV [V]High volutage dependences of counting
rate taken by changing the threshold.

Fig.4.

0

100

200

300

400
500
600
Drift Time [nsec]

Drift time distribution for hits fromwhich a track is reconstructed.

of electrons in a cell is 20-25 µm/ns. The width of about 400 ns corresponds to the cell size of 10 mm.
Figure 5 and 6 show evaluated efficiency of each wire for X layers and Y layers. In whole, efficiency isbetter than 95%.
Figure 7 shows evaluated resolution of each wire for Y layers. The resolution σ is calculated by afollowing formula,σ=√

σ1 σ2 ,

where σ1 and σ2 are sigmas of residual distribution including and excluding a wire focused, respectively.
The resolution of 150 µm are achieved. Furthermore, the drift length dependences of the resolution
shown in Fig. 8. It is found that the resolutions reach 100 µm at the middle of the cell, whereas they
become about 200 µm near the sense wire and outer circumference of the cell. The analysis for X layers
are ongoing.

§ 4. Conclusion and future prospects

The SCRIT electron scattering facility has been constructed to realize electron scattering off unsta-

ble nuclei. In 2016, several commissioning experiments with stable nuclear targets have been preformed.

Layer0
Layer2

1.1

1.3
1.1

1

1
0.9

0.8

0.8

0.7

0.7
0

Fig.5.

10

20

30

40

50

400

Layer0Layer1
Layer2
Layer3

300

0.6

60
Wire#

Efficiency of each wire of X layers.

200

0

Fig.6.

100

2

4

Layer1
Layer3

6

8

10

12
Wire#

Efficiency of each wire of Y layers.

400

Layer0Layer1
Layer2
Layer3

300
200
100

0
0

Fig.7.

Layer0Layer2

1.2

0.9

0.6

Resolution [um]Layer1
Layer3

Efficiency

1.3
1.2

Resolution [um]Efficiency

84

2

4

6

8

10

0
0

12
Wire#

High volutage dependences of counting
rate by changing the threshold are plotted.

Fig.8.

2

4

6

8
10
Drift length [mm]High volutage dependences of counting
rate by changing the threshold are plotted.

In order to realize the experiment with unstable nuclear target, improvements of target preparation
systems to achieve much higher luminosity have been conducted. The WiSES will be also updated byintroducing FDC2 and measuring the three-dimentional magnetic field map. The performance study of
FDC2 is still ongoing.
After these improvements, elastic electron scattering experiment for unstable nucleus will be performed soon.

References[1]

M. Wakasugi et al.: Nucl. Instr. Meth. B317, 668 (2013).

[2]

K. Tsukada et al.: ELPH Annual Report 2014 Vol. 5, Tohoku University, 125 (2014).

[3]

K. Tsukada et al.: ELPH Annual Report 2015 Vol. 6, Tohoku University, 99 (2015).

[4]

T. Suda and H. Simon: Prog. Part. Nucl. Phys., 96, 1 (2017).

[5]

K. Tsukada et al.: Phys. Rev. Lett. 118, 262501 (2017).

[6]

K. Tsukada et al.: Hyperfine Interact. 240, 102 (2019).

[7]

T. Ohnishi et al.: Nucl.Instrum.Meth. B317, 357-360 (2013).

[8]

M. Wakasugi et al.: Rev. Sci. Instrum 89, 095107 (2018).

ELPH Annual Report, Tohoku University (2018)85

Status of the LEPS2-solenoid experiment in 2018
Atsushi Tokiyasu1 for LEPS2 collaboration
1

Research Center for Electron Photon Science, Tohoku University, Sendai, 982-0826

The LES2-solenoid experiment is designed for multi-purpose apparatus to study the hadron photoproduction mechanism at SPring-8. One of the detectors of the LEPS2 experiment is Aerogel Cherenkov
Counter. The design work for the detector has been completed and performance test is carried out by
positron beam at SPring-8. Construction for the main detector components were almost completed, thus
the detector commissioning for system integration are performed with available detectors in 2018. γ
beam was induced to CH2 target which was installed inside detector systems, and detector performancewas evaluated by the charged or non-charged particles from the reaction events. A Significant amount ofdata have been accumulated for detector performance evaluation and developing analysis codes. Comissioning run will be continued through next FY, and physics experiment is planned after 2020.

§ 1. The LEPS2-solenoid experiment and detector systems
The LES2-solenoid experiment is designed for multi-purpose apparatus to study the hadron photoproduction mechanism at SPring-8. A high intensity γ beam by Backward Compton Scattering is used
to search for exotic hadron systems. One of the physics theme is a search for K − pp bound state. K − ppbound state was exotic nuclei which contains K − meson as component.
Two distinguished signals expected from the K-pp bound state have been reported via pi- and Kinduced experiment at J-PARC [1] [2].. However, the results, especially for binding energy obtained
from those experiments, are not consistent. Moreover, there is no theoretical explanation to describe
consistency between those results are available to date. Therefore, a new experiment to identified theK − pp with a different probe is mandatory. Photo-production reaction is complementary to hadron reaction, and the LEPS2-solenoid experiment will provide essential information to investigate the internal
structure of the K − pp bound state.
Photo-production reaction is complementary to hadron reaction, and the LEPS2-solenoid experiment will provide essential information to investigate the internal structure of K − pp bound state.
The overview of the LEPS2 solenoid detector system is shown in Fig. 1 The LEPS2 solenoid detector
systems is composed of Start Counter(SC), Time Projection Chamber(TPC), Drift Chambers(DCs), Aerogel Cherenkov Counter (AC1, AC2), Resistive Plate Chamber (RPC), and Barrel-γ (Bγ). These detectors
are installed inside solenoid magnet with the strength of 1 T, and used to detect both of charged particles

86

Fig.1. LEPS2 solenoid detector systemand γ from the hadron reactions. Among these detectors, ELPH is taking charge of developing AC2 andBγ. In the following section, the status of the development these counters will be reported.

§ 2. AerogleCerenkov Counter
Aerogel Cherenkov Counter (AC) will be used to identify K +/− particles from the target. There
are two types of AC. One is AC1 installed between TPC and DC1, and the another is AC2 installed
between DC1 and DC2. The difference of two ACs are index of Aerogels. Aerogel with index of 1.05 will
be used for AC1, and Aerogel with index of 1.03 are used for AC2. In this Fiscal year the geometricaldesign of AC2 was determined, and a proto-type detector was produced (Fig. 2). The performance check
was performed by using electron beam at SPring-8 and proton beam at CYRIC in Tohoku University.
We found the detection efficiency for π is enough, but large background exists coming from reflectormaterials. Another study for the selection of the material is on-going. The detail for AC2 development issummarized in [3]§ 3. Barrel-gammma
The Barrel-γ is a sampling calorimeter system composed of multi-layers of Lead and Scintillator
plates. Two PMTs were attached at the both edges to read out the light signals. In 2018, data acquisition
system was newly constructed, and by using beam at SPring-8. γ beam was induced to CH2 target
which was installed inside the solenoid magnet, and γ from the target was used to evaluated the energy
resolution. Non-charged particles are selected by other counters like SC, and pulse charge and time
information were collected. Figure 3 shows the correlation between light output ratio time difference of
two PMTs, which means the hit positions. We can see clear locus on this plot. Now analysis is on-goingto reconstruct π 0 peak.

87

Fig.2.

A picture of proto-type AC

Fig.3.

correlation plot of Bγ signal

88§ 4. Other detectors
In adittion to AC and Bγ, performances of TPC and DCs are also evaluated in comissioning run.
Track reconstruction codes for TPC and DCs were developed, and we succeced to reconstruct the tracks
from the target. We developed to adjust the relativistic location of DCs too. The evaluation of he position
resolution and momentum resolution of TPC and DCs is on-going.

§ 5. Summary
The LEPS2-solenoid experiment is multi-purpose experiment to study the hadron photoproduction
mechanism at SPring-8. Aerogel Cherenkov Counter and Barrel-γ Counter were developed by ELPH.
The performance of these detectors were evaluated by electron beam or γ. The beam commissioning of
the LEPS2 experiment will be continued in 2019, and after preparing all detectors, physics run will bestarted.

References[1]

Y. Ichikawa et al. :Prog. Theor. Exp. Phys (2015) 021D01[2]

S. Ajimura et al.:Phys. Lett. B 789 (2019) 620-625[3]

C. Yoshida : Master Thesis (2018)

ELPH Annual Report, Tohoku University (2018)89

Recent results of SPring-8 LEPS2/ BGOegg experimentN. Muramatsu1 , T. Hashimoto2 , Y. Matsumura2 , M. Miyabe1 , T. Nam2 ,H. Shimizu1 , N. Tomida2 , J.K. Ahn13 , W.C. Chang4 , J.Y. Chen5 , S. Daté3 ,T. Gogami6 , H. Hamano2 , Q.H. He15 , K. Hicks7 , T. Hiraiwa2 , Y. Honda1 ,T. Hotta2 , Y. Inoue1 , T. Ishikawa1 , I. Jaegle8 , J.M. Jo13 , Y. Kasamatsu2 ,H. Katsuragawa2 , S. Kido1 , Y. Kon2 , S. Masumoto9 , K. Miki12 , K. Mizutani2 ,T. Nakamura12 , T. Nakano2 , M. Niiyama14 , Y. Nozawa18 , Y. Ohashi3 ,H. Ohkuma2 , H. Ohnishi1 , T. Ohta18 , M. Oka2 , M. Okabe1 , K. Ozawa11 ,C. Rangacharyulu16 , Y. Sada1 , M. Sasagawa1 , T. Shibukawa9 , R. Shirai1 ,K. Shiraishi1 , E.A. Strokovsky17,2 , Y. Sugaya2 , M. Sumihama12,2 , S. Suzuki3 ,S. Tanaka2 , A. Tokiyasu1 , Y. Tsuchikawa1 , T. Ueda1 , H. Yamazaki19 ,R. Yamazaki1 , Y. Yanai2 , T. Yorita2 , C. Yoshida1 , and M. Yosoi2
1

Research Center for Electron Photon Science, Tohoku University, Sendai, Miyagi 982-0826, Japan
2
3

Research Center for Nuclear Physics, Osaka University, Ibaraki, Osaka 567-0047, Japan

Japan Synchrotron Radiation Research Institute (SPring-8), Sayo, Hyogo 679-5198, Japan
4
5

6
7
8

Institute of Physics, Academia Sinica, Taipei 11529, Taiwan

National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
Department of Physics, Kyoto University, Kyoto 606-8502, Japan

Department of Physics and Astronomy, Ohio University, Athens, OH 45701, USA

Department of Physics and Astronomy, University of Florida, Gainesville, FL 32611, USA
9

Department of Physics, University of Tokyo, Tokyo 113-0033, Japan
10

11

RIKEN Nishina Center, Wako, Saitama 351-0198, Japan

Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki
305-0801, Japan
12
13

Department of Physics, Korea University, Seoul 02841, Republic of Korea

14
15

Department of Education, Gifu University, Gifu 501-1193, Japan

Department of Physics, Kyoto Sangyo University, Kyoto 603-8555, Japan

Department of Nuclear Science & Engineering, College of Material Science and Technology, Nanjing University of
Aeronautics and Astronautics, Nanjing 210016, China

16
17

Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada

Laboratory of High Energy Physics, Joint Institute for Nuclear Research, Dubna, Moscow Region, 142281, Russia
18

19

Department of Radiology, The University of Tokyo Hospital, Tokyo 113-8655, Japan

Radiation Science Center, High Energy Accelerator Research Organization (KEK), Tokai, Ibaraki 319-1195, Japan§ 1. Introduction
At SPring-8 LEPS2 beamline, a tagged photon beam is available in the energy range of 1.3–2.4 GeV
by laser Compton scattering [1]. A beam intensity reaches 1–5 × 106 cps. This beamline has been constructed at the long straight section of the electron storage ring, where a beam divergence is locallysuppressed to 12 µrad for the horizontal direction, so that the photon beam can be extracted to the
LEPS2 experimental building about 130 m apart from the Compton scattering point. The LEPS2 experimental building has a large space, which enables to run two experimental setups: namely, the BGOegg

90

Fig.2.
Fig.1.

Setup of the BGOegg experiment. Only theapparatus closely related to the signal selection of single meson photoproduction isshown in a side view. A wall of resistive
plate chambers (RPC) is also located 12.5 mof the target in the forward acceptance.

Photon beam asymmetries forπ 0 photoproduction, measured by
BGOegg (closed circles), LEPS
(open crosses), and Daresbury(closed stars) at 2200 < Eγ <2300 MeV.
Solid and dashedcurves represent partial wave
analysis calculations by SAID
and Bonn-Gatchina groups, respectively.

experiment with a high precision electromagnetic calorimeter and the charged particle spectrometer experiment using a large solenoid magnet. Both experiments have assembled large solid angle detector
systems, and they are separately running while adjusting experimental periods.
The BGOegg experiment has been carried out in the first phase of LEPS2 beamline operation. In
2014–2016, experimental data have been alternatively collected by using a 54 mm-thick liquid hydrogentarget or a 20 mm-thick carbon target. Figure 1 shows the BGOegg experimental setup. The polar
angles from 24◦ to 144◦ around the target are covered by an electromagnetic calorimeter, which consistsof 1, 320 BGO crystals in an egg shape and is therefore called “BGOegg”. The charge identificationof BGOegg calorimeter hits is done by using inner plastic scintillators (IPS), arranged in a cylindricalshape. The energy resolution of the BGOegg calorimeter is 1.3% for 1 GeV γ rays, providing the highest
performance in the world [2]. For the forward acceptance hole of the BGOegg calorimeter, a planar drift
chamber (DC) and resistive plate chambers (RPC) are placed to detect charged particles.

§ 2. Single meson photoproduction off the proton
We have analyzed the liquid hydrogen target data in order to search for baryon resonances in thes-channel of single meson photoproduction reactions, such as γp → π 0 p, ηp, and ωp. The masses andwidths of baryon resonances are not well described by constituent quark models, except for ground andlow excited states. Experimental investigation of baryon mass spectra is recognized to be important forunderstanding hadron structures. Because excited baryon states have wide widths and overlap witheach other, it is effective to study various photoproduction reactions systematically and to accumulate
measured observables with the use of photon beam polarization. For example, π 0 photoproduction is91
contributed from both nucleon and ∆ resonances, while photoproduction of the η or ω meson arises only
from nucleon resonances thanks to an isospin filter. If polarization observables are measured together
with differential cross sections for these reactions, highly excited states with weaker amplitudes can beextracted through an interference effect. However, the results of photon beam asymmetries, obtained byusing linear polarization, are insufficient in the photon beam energy range of 2 GeV or more for all theabove reaction modes. The LEPS2 beamline has an advantage for generating a linearly polarized photon
beam via laser Compton scattering, and the BGOegg experiment has obtained such new experimental
results.
In the analyses, the π 0 and η mesons are identified by detecting a γγ decay, and the ω meson is reconstructed from a π 0 γ decay. The energy and flying direction of those final state γ’s are measured at the
BGOegg calorimeter. A recoil proton is detected by the BGOegg calorimeter or the forward drift chamber to measure its emission angle. Simultaneously, the energy of an incident photon beam is determined
event by event on the basis of a momentum analysis for a recoil electron at laser Compton scattering.
Then, a kinematic fit is performed by requiring four-momentum conservation. Here the invariant massof γγ is also constrained to the nominal value of π 0 or η, which are available by Particle Data Group(PDG) [3]. A χ2 probability cut after the kinematic fit eliminates background event, resulting in theclean signal samples of π 0 , η, and ω photoproduction of about 650K, 56K, and 37K events, respectively.
The detailed results of differential cross sections and photon beam asymmetries for π 0 photoproduction are described in another paper [4]. The statistical accuracies of them are comparable to theexisting experimental results. The obtained differential cross sections generally agree with the results of CLAS, GRAAL, and LEPS experiments [5–7]. On the other hand, a difference from the CBELSA and CBELSA/TAPS results is seen for backward π 0 production angles in the low energy regionof Eγ < 1.9 GeV [8, 9]. As for the photon beam asymmetries, we have achieved a wide angle coverage
at Eγ > 1.9 GeV, for the first time. A steep drop of the photon beam asymmetry has been observed
at extremely backward π 0 angles in this high energy region, as shown in Fig. 2. None of the existing partial wave analysis models reproduce the measured photon beam asymmetries at high energies[10, 11]. In the analyses for η and ω photoproduction, the measurements of differential cross sections
and photon beam asymmetries are also in progress, showing differences from the existing partial wave
analysis models in the high energy region where the multipole amplitudes are not well fixed. In particular, the differential cross sections of η photoproduction at the most backward angles suggests a wide√bump structure around s ∼ 2.2 GeV.

§ 3. η ′ meson mass in nuclei
The η ′ meson gains a large mass due to the UA (1) anomaly, and it has been discussed that its
mass may be reduced inside a nucleus by the partial restoration of chiral symmetry breaking under ahigh-density environment. While theories such as the linear sigma model [12] and the NJL model [13]predict a large mass reduction of 80-150 MeV/c2 , the η ′ N scattering length measurement at COSY-11[14] and the measurements of transparency ratio and sub-threshold cross sections at CBELSA/TAPS

92[15, 16] indirectly suggest smaller amounts of reduction, which do not exceed about 50 MeV/c2 . In the
BGOegg experiment, we are aiming for more direct observation of an η ′ mass change by using the carbon
target data. For this purpose, we have adopted two analysis methods, searching for (1) nuclear medium
modification signals in the γγ invariant mass distribution from η ′ decays, and (2) nuclear bound states ofthe η ′ meson in the missing mass distribution with a high energy proton detection at extremely forward
angles.
3.1 Medium modification of the η ′ mass
In order to explore the change of η ′ meson mass in carbon nuclei, we detect η ′ → γγ decays, whosebranch fraction is 2.22% in vacuum, at the BGOegg calorimeter, and measure the invariant mass distribution of two γ rays. There is a benefit that the calorimeter can detect those γ rays without muchinfluence of interaction in the target substance. As the produced η ′ meson has a smaller momentum, therate of decay in the carbon nucleus increases, possibly enhancing mass reduction signals below the peakstructure due to η ′ decays outside the nucleus in the γγ invariant mass distribution.
In searching for the medium modification of the η ′ mass, it is important to understand the γγ invariant mass spectrum shape of decays outside the nucleus. This shape is influenced by energy andangular resolutions for γ detection, and is evaluated by a realistic Monte Carlo (MC) simulation that
reproduces the detector setup and response in the BGOegg experiment. The validity of the mass resolutions obtained by MC simulations is proved by confirming it matches with the real data resolutions in
any momentum range for the processes η → γγ and ω → π 0 γ → γγγ. The mass resolution estimatedusing a MC simulation is also consistent with that for the liquid hydrogen target data.
In addition to the η ′ meson decays outside the nucleus, photoproduction of multiple π 0 ’s, π 0 η,
etc. are large background soures against the search for medium modification. These processes include
many γ rays in the final state, but are contaminated into the signal sample by missing some of themin the forward acceptance hole of the BGOegg calorimeter. The reaction γp′ → π 0 π 0 p contributes asa main background caused by a physical process. In the region of a large invariant mass, there also
remain backgrounds from unphysical processes, in which particles originating from cosmic rays and upstream interactions are detected by the BGOegg calorimeter. The invariant mass spectra and amountsof these processes are estimated by MC simulations and individual background-tagged samples in thereal data. It has been confirmed that the mass spectra can be fitted reasonably with a smooth function
represented by exp(p0 + p1 x + p2 x2 ) for any process. This function can be also applied to the invariant
mass distribution added with the ratio of each evaluated background amout. The χ2 for this overall fit
does not change even if variation is given to the background ratio.
The obtained background spectra have been simultaneously fitted to the γγ invariant mass distribution in the real data, as shown in Fig 3. This figure is plotted for events where the momenta ofη ′ mesons are over 1 GeV/c. In the small invariant mass region, a background component due to thereaction ω → π 0 γ → γγγ with a missing γ ray is also considered. The reduced χ2 of the backgroundfit for the high momentum region is 61.8/59, indicating no signals of medium modification. For more

93

Fig.3.

A background fit to the γγ invariant
mass distribution in the carbon target
data. η ′ momenta are required to begreater than 1 GeV/c.

Fig.4.

Sensitivity of η ′ mass modification for
the near future BGOegg experimentusing a copper target.

quantitative evaluation of statistical significance, the invariant mass distributions of medium modification signals are derived from simulations with various assumptions of mass reduction and width. Then,χ2 fits are performed in two cases, when only the background functions are fitted and when the signal
function is additionally included. The signal significance is calculated based on the difference of χ2 ’s.
Before scanning the signal significance, the condition to select η ′ ’s with lower momenta has been decided
to be a region below 1 GeV/c so that a statistical figure of merit for the ratio of decays inside the nucleus
should be maximized over background fluctuation. The final siginificance evaluation will be soon carriedout for the low momentum region.
3.2 η ′ -mesic nuclei
As another way to probe the decrease of η ′ mass inside the nucleus, we are also searching for nuclear
bound states of the η ′ meson. In this method, high-energy protons emitted to extremely forward angles
are detected by RPC for tagging photoproduction of low-momentum η ′ mesons in carbon nuclei. Proton
momenta are measured from time-of-flight with high precision, and missing masses for the C(γ, p)
reaction are calculated to seek the bound state signals below the threshold of quasi-free η ′ production.
Furthermore, we increase a S/N ratio by using the BGOegg calorimeter, which detects signals thatthe bound η ′ mesons are absorbed by protons in the nucleus and cause conversions to back-to-backη-p. Becase the nuclear absorption rate of the η ′ meson is unknown, it is ideal to advance the twocomplementary analyses with the γγ invariant mass and the C(γ, p) missing mass.
The search for the nuclear bound states of the η ′ meson has been performed earlier in the C(p, d)reaction experiment at GSI, resulting in no sign of such signals in the missing mass distribution [17].
In contrast, the BGOegg experiment is characterized by trying to detect the absorption and conversion
signals at the same time. The BGOegg experiment can also detect quasi-free photoproduction of η ′94mesons, enabling the normalization of theoretical predictions for the differential cross sections of boundsignals. Importance of the latter point is understandable from the existing pionic atom experiments,
where the bound level spectrum has been well reproduced by theoretical calculations but it has beendifficult to match their differential cross sections. We have measured the experimental yield of η ′ escapesfrom the carbon nucleus by detecting a forward proton at the RPC and an η ′ → γγ decay at the BGOegg
calorimeter. Our measurement indicates this yield is about 1/4 of the theoretical calculation [18].
In the analysis detecting the conversion signals to η-p, the processes like η photoproduction with ascattering of the reaction product from other nucleons remain as final backgrounds. These backgrounds
have kinematic features such as η mesons or protons are likely to be produced in the forward direction.
Event selection conditions with a sufficient S/N ratio for signal detection are being determined, andthe existence of bound signals will be inspected in the missing mass distribution for the extremely forward proton. We also compare the measured spectrum with the theoretical calculation of missing mass
distribution based on the NJL model [18].
3.3 Near future plan
The forward detectors for charged particles in the BGOegg experimental setup have been replacedby an additional electromagnetic calorimeter, called a “Forward Gamma” detector. It consists of 252
PbWO4 (PWO) crystals, each of which has a size of 22 × 22 × 180 mm3 . The charge of a Forward Gamma
hit is identified by a two-dimensional hodoscope array (Forward Plastic Scintillators) [19], placed in frontof this calorimeter. By covering most of solid angles with calorimeters, an ambiguity in judging reaction
processes, caused by missing particles, are efficiently reduced. In terms of the medium modification
search for the η ′ meson, a main background coming from the reaction γp′ → π 0 π 0 p decreases lessthan one order of magnitudes. This feature provides great advantage in suppressing fluctuation of abackground spectrum, which fakes medium modification signals.
In the BGOegg experiment, the target is being changed to copper, which has a larger nuclear radius,
for further data collection using the new detector setup described above. In 2017, we have collected test
data with a copper target, whose thickness corresponds to 0.1 radiation length in the same way as theprevious program with a carbon target. Because the uncertainty of a reaction point is reduced by thechange of target thickness from 20 mm to 1.5 mm, the resolution of γγ invariant mass for η ′ is improved
from 20 MeV/c2 to 13 MeV/c2 . Moreover, in 2018, we have increased the thickness of a copper target bya factor of 5, and finished short-term data taking with partial operation of the Forward Gamma detector
and the Forward Plastic Scintillators. After the preparation of a data acquisition system for the newsetup is completed, the BGOegg experiment will be resumed while adjusting time sharing of the LEPS2
beamline with the solenoid experiment. Figure 4 shows the signal sensitivity of medium modificationthat can be achieved by planned data collection as a function of the binding energy. It is assumed that acopper target with 0.5 radiation length will be irradiated by a photon beam of 2×106 cps for 4 months andthat a background level will be reduced by an order of magnitude with the new experimental setup. The
vertical axis represents 90% upper limits for a background fluctuation of σ ∼ 13 MeV/c2 to be recognized

95
as medium modification signals in the form of a percentage to the quasi-free η ′ photoproduction. If the
momentum range of produced η ′ mesons is limited up to several hundreds MeV/c, the rate of γγ decays
inside the nucleus is expected to be a few percent, so that the planned data collection must provide
enough signal sensitivity.

§ 4. Summary
The BGOegg experiment is conducted as research programs to understand hadron natures by using
a 1.3–2.4 GeV photon beam at the SPring-8 LEPS2 beamline. Data collected using a liquid hydrogentarget is analyzed to search for baryon resonances. In particular, photon beam asymmetries have beenmeasured with the advantage of high linear polarization in a high energy region where experimental
results are scarce. The collected data will be further utilized to study highly excited baryons through thephotoproduction of η ′ or multiple mesons. In addition, we analyze the carbon target data to investigate
medium modification of the η ′ mass in the γγ invariant mass and to search for nuclear bound states in
the C(γ, p) missing mass. In the near future, we will use a copper target whose thickness is increased to
0.5 radiation length, and will employ an experimental setup to cover the forward acceptance hole of the
BGOegg calorimeter with another electromagnetic calorimeter made of PWO crystals. The contributionof backgrounds due to multiple π 0 photoproduction must be largely suppressed, and medium modification signals can be detected with sufficient statistical accuracy in half-year data collection. The newexperimental setup with increased calorimeter acceptance allows the detection of all final state particles
with charge identification, and enables data collection even for a deuterium target.

References[1]

N. Muramatsu, et al., Nucl. Instr. Meth. A 737 (2014) 184; N. Muramatsu, ELPH Report 2044-13(2013) or arXiv:1307.6411.

[2]

T. Ishikawa, et al., Nucl. Instr. Meth. A 837 (2016) 109.

[3]

M. Tanabashi, et al. (Particle Data Group), Phys. Rev. D 98 (2018) 030001.

[4]N. Muramatsu, et al., Phys. Rev. C 100 (2019) 055202.

[5]

M. Dugger, et al., Phys. Rev. C 76 (2007) 025211.

[6]

O. Bartalini, et al., Eur. Phys. J. A 26 (2005) 399.

[7]

M. Sumihama, et al., Phys. Lett. B 657 (2007) 32.

[8]

O. Bartholomy, et al., Phys. Rev. Lett. 94 (2005) 012003.

[9]

V. Crede, et al., Phys. Rev. C 84 (2011) 055203.

[10] http://gwdac.phys.gwu.edu/[11] https://pwa.hiskp.uni-bonn.de/[12] S. Sakai and D. Jido, Phys. Rev. C 88 (2013) 064906.
[13] H. Nagahiro, M. Takizawa, and S. Hirenzaki, Phys. Rev. C 74 (2006) 045203.

96[14] P. Moskal, et al., Phys. Lett. B 482 (2000) 356; E. Czerwinski et al., Phys. Rev .Lett. 113 (2014)
062004.
[15] M. Nanova, et al., Phys. Lett. B 710 (2012) 600.
[16] M. Nanova, et al., Phys. Lett. B 727 (2013) 417.
[17] Y.K. Tanaka, et al., Phys. Rev. Lett. 117 (2016) 202501.
[18] H. Nagahiro, JPS Conf. Proc. 13 (2017) 0100010.
[19] T. Ueda, Master Thesis, Tohoku University (2019).

ELPH Annual Report, Tohoku University (2018)

97

Production of a high energy γ beam via inverse Compton
scattering of soft x-rays from a short undulator
Norihito Muramatsu1 , Masahiro Okabe1 , Shinsuke Suzuki2 , Schin Daté2 ,Hajime Shimizu1 , Haruo Ohkuma3 , Kazuhiro Kanda4 , Shuji Miyamoto4 ,Tetsuo Harada4 , Takeo Watanabe4 , Manabu Miyabe1 , and Atsushi Tokiyasu1
1Research Center for Electron Photon Science, Tohoku University, Sendai, Miyagi 982-0826, Japan
2

Japan Synchrotron Radiation Research Institute (SPring-8), Sayo, Hyogo 679-5198, Japan
3

4

Research Center for Nuclear Physics, Osaka University, Ibaraki, Osaka 567-0047, Japan

Laboratory of Advanced Science and Technology for Industry, University of Hyogo, Kamigori, Hyogo
678-1205, Japan§ 1. Introduction
Usually, a high-power laser beam is injected into the electron storage ring for the production of ahigh-energy γ beam via inverse Compton scattering. In our project, soft x-rays of about 92 eV are being
injected instead, in order to achieve much higher energies for the γ beam. Figure 1 shows the energy
spectrum of such a beam at SPring-8-II, where the electron beam energy will be lowered to 6 GeV. Thisγ beam must be useful for new generation experiments of hadron physics by enabling the production ofheavier particles [1].
We plan to carry out a series of demonstration experiments to develop techniques for the inverse
Compton scattering of soft x-rays at NewSUBARU, whose electron energy is 1 or 1.5 GeV. In case of the
1 GeV operation, the maximum energy of a γ beam is extended to 585 MeV at Compton edge, comparedwith 51 MeV by the injection of 355 nm ultraviolet laser. For the demonstration experiments, we use ashort undulator (total length: 2.28 m, period length: 7.6 cm) at BL07 [2] as an x-ray source, and thenreflect the radiated x-rays backwardly into the original straight section. A Mo/Si multi-layer mirror will
be installed at BL07A for this reflection.

§ 2. Preparation of beamline chambers and associated detectors
In FY2018, the experimental setup was designed for NewSUBARU BL07A in detail. Accordingly,
two vacuum chambers were newly installed at this beamline. One large chamber with a size of W 1120 ×

D820 × H610 mm3 has been set up 16.7 m downstream of the undulator center. A multi-layer mirror
will be placed on high precision stages inside this chamber with cooling water circulation. The otherchamber, shown in Fig. 2(a), has been installed 2.6 m upstream of the large mirror chamber, in order tomonitor radiated and reflected x-rays. A wire scanning detector was mounted for the measurement of
their profiles and relative intensities based on an increase of micro current due to a photoelectric effectat φ0.2 mm tungsten wires. The tugsten wires were directed vertically and horizontally with a moving
stage attached to an air cylinder.

98

Fig.1.

An energy spectrum of a γ beam via inverse Compton scattering of 92 eV x-rays from
6 GeV electrons at SPring-8-II (solid line). The other spectrum (dashed line) indicatesthe inverse Compton scattering of 355 nm laser light from 8 GeV electrons at SPring-8.

For the energy measurement of a γ beam produced by inverse Compton scattering, a high resolution
electromagnetic calorimeter (∆E/E = 1.7% at 1 GeV) was made by assembling nine PbWO4 (PWO)
crystals, the individual size of which is 20 × 20 × 200 mm3 . It was set up just downstream of theswitching mirror for BL07A and BL07B inside the storage ring tunnel, as shown in Fig. 2(b). A γ-beamprofile monitor was also prepared by crossing 1 mm2 scintillating fibers in the area of 50 × 50 mm2 .
The readout of scintillating fibers were done in each two channels (namely, 2 mm digitization) by using
multi-pixel photon counters (MPPC). For making a trigger signal at data taking, a veto counter, a thinlead converter, and a trigger counter were additionally placed upstream of the profile monitor and the
PWO calorimeter.

§ 3. Development of a cylindrical x-ray mirror
A base plate for the Mo/Si multi-layer mirror was developed with a low thermal expansion glass
ceramic (Zerodur). Because the switching mirror of BL07 possesses a spherical surface, the x-rays at thereflection mirror chamber are parallel in the horizontal direction but divergent for the vertical component. This feature was confirmed by the ray trace simulation SHADOW [3], as shown in Fig 3. In orderto focus the reflected x-rays at the straight section of BL07, we need a cylindrical multi-layer mirror witha curvature radius of 16.7 m, which corresponds to the distance between the mirror and the Compton
scattering point. A good focusing behavior was also confirmed by SHADOW.
Based on this study, we developed a cylindrical x-ray mirror base with a unique method by using a
5 mm-thick and 80 × 80 mm2 Zerodur plate. Details of the cylindrical mirror production are describedin Ref. [4]. The Zerodur plate has been finally cut in 50 × 50 mm2 , which is large enough comapred withthe x-ray beam size of about 20 × 20 mm2 . The produced curvature radius was confirmed by measuring

99

Fig.2.

Pictures of (a) x-ray monitor chamber and (b) γ-beam detectors, installed at NewSUBARU BL07A.

Fig.3.

SHADOW simulation results of the x-ray positions and slopes at the reflection mirror
chamber in the horizontal (x / x′ ) and vertical (y / y ′ ) directions.

the maximum depth at the mirror surface center with a micro-gauge (18.7 µm for the 50 mm width) andalternatively counting the number of Newton fringes with a flat plate under a Na lamp (128 interference
fringes for the 50 mm width). The mirror base is now in the process of multi-layer coating by Mo/Si. The
reflectivity will reach 60% for the backward reflection of 92 eV x-rays [5].

§ 4. A test experimet with a bremsstrahlung γ beam
The performance of x-ray and γ-beam detectors has been tested by using x-rays from the BL07
short undulator and a γ beam from gas bremsstrahlung inside the storage ring. Fig. 4(a) shows thevertical profile of undulator x-rays at the wire scanning detector. A wire position during the air cylinder
operation was determined based on the voltage measurement by a potentiometer. This test measurement
was performed with a narrow slit, so the observed x-ray beam size was about 1 mm in σ. A variation of

100

Fig.4.

(a) Vertical profiles of undulator x-rays at the wire scanning detector. The solid anddashed lines were obtained when the undulator gap was set to 48 mm and fully opened,
respectively. (b) Energy spectra of a bremsstrahlung γ beam at the PWO calorimeter.
The solid and dashed lines correspond to the storage-ring operation energies of 1 and
1.5 GeV, respectively. (c) A Two-dimensional profile of a bremsstrahlung γ beam at theγ-beam profile monitor.

the x-ray beam intensity is clearly seen depending on the undulator gap setting.
Fig. 4(b) shows the energy spectra of γ beams from gas bremsstrahlung. Both spectra with NewSUBARU operation at 1 and 1.5 GeV were measured by using the PWO calorimeter. The linearity ofenergy measurement can be confirmed by comparing the upper edges of two spectra. Fig. 4(c) shows aresult of γ-beam profile measurement by using the γ-beam profile monitor, made of scintillating fibers.
The γ beam is narrow enough with a gaussian sigma of about 6 mm.

§ 5. Prospect of the demonstration experiments
After the completion of the Mo/Si multi-layer coating, we will test the production of a γ beam via
inverse Compton scattering of undulator x-rays. We will confirm technical issues on the heat load of an
x-ray mirror, the cooling capacity of a mirror holder, the reflectivity of x-rays, the focussing performanceof a cylindrical x-ray mirror, and so on. Then we will measure the energy spectrum and intensity of an
x-ray induced γ beam for comparison with theoretical estimations. Based on these developments, we will
move on a next step towards the production of a high energy and intensity γ beam, usable realisticallyfor next-generation hadron experiments. The developed techniques can be applied as one of beamlines
at electron storage ring facilities like SPring-8-II, KEK PF-AR, and SLiT-J.
This project is in progress under the support by JSPS KAKENHI for Challenging Research (Pioneering) Grant No.18H05325 [6].

References[1]

E. Klempt and A. Zaitsev: Phys. Rep. 454 (2007) 1.

[2]

K. Kanda, Y. Haruyama, M. Fujisawa and S. Matsui: Nucl. Instrum. Methods Phys. Res. A 467-468(2001) 500.

101
[3]

Using the old version ‘xop2.3’ available from http://www.esrf.eu/Instrumentation/software/dataanalysis/xop2.4[4]

M. Okabe, N. Muramatsu, and I. Ishikawa, ELPH Annu. Rep. 2018 (2019) 102.

[5]

T. Feigl, S. Yulin, N. Benoit, and N. Kaiser, Microelectron. Eng. 83 (2006) 703.

[6]

http://www.rcnp.osaka-u.ac.jp/ mura/kaitaku/

ELPH Annual Report, Tohoku University (2018)

102

Development of Multilayer Mirror for Producing a Next-generation
Photon Beam
Masahiro Okabe1 , Norihito Muramatsu1 , and Isamu Ishikawa2
1 Research Center for Electron Photon Science, Tohoku University, Sendai, Miyagi 982-0826
2 IK Technology Co., Minoh, Osaka 562-0045

Photon beams produced by inverse Compton scattering are commonly used in several facilities. For example LEPS
and LEPS2 experiments at Spring-8, where laser photons are used as incident photons. The energy of produced gammarays becomes higher if soft X-rays are used instead of laser. In this experiment, we developed a unique mirror to reﬂect
soft X-rays from an undulator to a storage ring. Because it was designed to have an extremely small and cylindricalcurvature, we established a new method for bending glass plates and utilizing a property of shape restoration to makethem curved. Mechanical polishing is widely used to producing a spherical surface, but it is not suited for a cylindricalone. When the new method to produce a high energy gamma-ray beam becomes available, we will be able to study
heavier hadrons than those in the current research programs with laser injection.

§ 1. Introduction
The maximum energy of gamma rays produced by inverse Compton scattering is expressed by
Eγ =4ω0 Ee2,2
m c4 + 4ω0 Ee(1)where ω0 and Ee represent the energy of incident photons and electrons, respectively, and m represents electron mass.
When the energy of storage ring electrons is 8 GeV and that of incident photons is 3.5 eV, which corresponds to the laser
wavelength of 355 nm used at LEPS2, the maximum energy of gamma rays is 2.4 GeV. If incident photon is soft X-ray
photons with the energy of about 100 eV, it becomes 7.4 GeV.
To verify energy raise by inverse Compton scattering, we are researching at New SUBARU synchrotron radiation
facility, which has 1.0 GeV storage ring (the maximum energy is 1.5 GeV ). There is an undulator on the ring and it can
produce about 100 eV X-ray beam. We are trying to reﬂect undulator photons backwardly into the storage ring. The
experimental setup is shown in Fig.1. The beam line has a feature that a photon beam has a divergence in the verticaldirection, which arises from its speciﬁc structure. To solve this problem, we need a mirror which has a cylindricalsurface, whose radius of curvature is 16.7 m. A commonly used method is rotating glass plate and mechanical polishingfor a high-precision spherical surface. However it’s not suited to a cylindrical surface. We developed a new method tomake glass plates that met performance mentioned above.

103

Fig.1. Setup at New SUBARU beam line

§ 2. Method of mirror base production
The process to make glass plates curved is illustrated in Fig. 2. The glass we have adopted is Zerodur, which
possesses a low thermal-expansion property. First of all, we pressed the edges of them to make convex curves and ﬁxed
with epoxy resin adhesive. Then we polished the convex surfaces until they became ﬂat with the surface roughness of afew nm. The adhesive can be melted when it’s heated above about 200◦C. After solving the bending stress of the glass
plates, the ﬂatly polished planes have concave curves.
To accomplish this process, we made a jig tool shown in Fig. 3. The left panel describes a conceptual design, andthe picture of the constructed jig is shown in the right panel. We put two stainless wires of a 0.2 mm diameter with aninterval of 30 mm. We pressed the glass edges with a lab-jack to make convex surfaces. Because it was necessary toapply equal pressures on both edges, we assembled a jig as shown in the upper side of the left panel of Fig. 3 (right). A
scale was used to measure the applied pressure.
To check the curvature radius during and after the production process, we performed a Newton Fringe (NF) test. It
represents an interference pattern of a convex surface relative to a ﬂat reference plane. The actual picture of NF is shownin ﬁgure4. We compared the observed interference pattern with the ideal calculation result, and adjusted the appliedpressure.
Following the production process mentioned above, the glass plates were pressed with a stress of 50 kg. Then
we prepared two sets of bended glass plates which were ﬁxed with adhesive. Even after releasing them from the jig,
the curvatures of convex surfaces were kept. Thereafter they were polished ﬂatly and relaxed from adhesive ﬁxing at
IK Technology Co. Currently they are in a process of forming a Mo/Si multilayer on their reﬂection surface at NTT
Advanced Technology Corporation. The multilayer is suitable for reﬂecting soft X-rays. The mirrors will be tested interms of their reﬂectivity and focusing performance.

104

Fig.2. Process to make concave curve

Fig.3. Abstract (left) / concrete (right) picture of equipment

Fig.4. Typical example of Newton fringeELPH Annual Report, Tohoku University (2018)

105(ELPH Experiment: #2887)

Phantom production for a multiple-isotope β-ray imaging system
T Fukuchi,1 H. Haba,2 and H. Kikunaga3
1

3

RIKEN Center for Biosystems Dynamics Research, Kobe 650-0047, Japan

2 RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, Japan

Research Center for Electron Photon Science (ELPH), Tohoku University, Sendai 982-0826, Japan

We have been developing a new type of β-ray imaging system, which is useful for multiple
tracers by detecting coincidence γ-rays with β-rays. To evaluate the performances of our developing
systems, we produced an imaging phantom of β-γ emitter 22Na. From a dual-isotope imaging using
the produced phantom and a standard source, we can clearly separate each nuclide by absence orpresence of the γ-ray coincidences.
§1. Introduction
Beta-ray imaging systems are widely used for various objects to obtain a 2-dimensional
distribution of β-ray emitting radioisotopes. A conventional β-ray imaging system is unsuitable formultiple-tracer imaging, because the continuous energy distribution of β-rays makes it difficult todistinguish among different tracers by energy information. Accordingly, we have been developing a
new type of β-ray imaging system, which is useful for multiple tracers by detecting coincidence γ-rays
with β-rays.
Figure 1 shows a photograph of thedeveloping β-ray imaging system. Our
β-ray imaging system is composed of
position-sensitive β-ray and γ-ray
detectors. The β-ray detector is a
Ce-Doped(La,
35×35×1-mm3(La-GPS)
scintillationGd)2Si2O7
detector [1], which has a 300-µm pitchof pixels by grooving processing [2, 3].
The γ-ray detector is a 43×43×16-mm3
bismuth germanium oxide (BGO)
scintillation detector. In this system, theβ-γ coincidence measurement can be
performed in parallel with β-ray single
measurement.

Fig. 1. Our developing β-ray imaging system with anadditional γ-ray detector.

§2. Phantom production
In order to evaluate the performances of our system, it is necessary to perform the phantom
imaging experiment, which visualize the already-known radio-tracer distributions. Therefore, we
carried out production of a β-γ emitter 22Na phantom. Sodium-22 is a positron-γ emitter with a half-106life of 2.6 years and emits a prompt γ-ray with energy of1275 keV.
We prepared a thin disk-shape target made of natural
Mg (24Mg isotope ratio: 79%) for production of imaging
phantom. This has 8 mm in diameters and 0.5-mm
thicknesses. The 3 hours high-energy photon irradiation
was performed by the ELPH accelerator with electronenergy of 50 MeV. Sodium-22 was produced by 24Mg(γ,pn)22Na reaction, and produced radioactivity of 22Na is2.85 kBq.
Fig. 2. Source positions for dual§3. Imaging experimentisotope imaging of 22Na and 45Ca.
To investigate the performance of multipleSources were allocated just on theisotope imaging, a measurement using produced 22Na
surfaceof β-ray detector.
phantom and a standard source 45Ca were carried out.
The 45Ca standard source has 5-mm diameter and an
activity of 1.41 kBq. Sources placement for this measurement is shown in Fig. 2. The measurement
was performed for 1 hour.
The reconstructed images from the single or coincidence data are shown in Fig. 3. We can clearlyobserve the 22Na and 45Ca phantoms in the image of the single data in Fig. 3 (a). While in the image
from the coincidence data (Fig. 3(b)), we successfully extracted the isolated image of the 22Na phantom.
In order to perform the multiple-tracer imaging for more practical objects, we are planning to
produce phantom of different
nuclides and more complicatedstructure in the future.
Acknowledgements
The authors thank to thefacility staffs of ELPH in Tohoku
University for supplying the highquality electron beam. The authors
thank Prof. Yamamoto for thedevelopment of the imaging
devices. This work was supported
by JSPS KAKENHI Grant Number
JP15H04770.

Fig. 3. Dual-isotope images 22Na and 45Ca) of β-ray single (a)and β-γ coincidence (b)References[1] A. Yoshikawa et al.: Crys Grow and Des. 15 (2015) 1642.
[2] T. Oshima et al.: Nucl Inst and Meth A803 (2015) 8.
[3] S. Yamamoto et al.: Jour of Inst 13 (2018) P05028.

ELPH Annual Report, Tohoku University (2018)107(ELPH Experiment : #2896)

Application of Single Comparator Method to Instrumental
Photon Activation Analysis
M. S. Reza1 , R. Taniguchi1 , J. Kaneko1 , and Y. Oura1
1

Department of Chemistry, Tokyo Metropolitan University, Hachioji, 192-0397

Single comparator method was applied to instrumental photon activation analysis. Various kindsof samples, mainly geochemical reference samples, were analyzed by IPAA using single comparator
method and accuracy of detemined elemental concentrations was examined. For many elements, thedetermined values were consistent with literature values regardless of samples. Although systematic
small deviations (-40 % - +50% ) from literature values were observed for some elements, the accuracyof the determination by our single comparator method is generally concluded to be good.

§ 1. Introduction

An activation analysis is a multielemental nondestructive analytical methods and has high sensi-

tivity. Popular activation analytical method is instrumental neutron activation analysis (INAA) using(n, γ) reaction induced by reactor neutrons. Instrumental photon activation analysis (IPAA) is one of activation analytical methods and uses mainly (γ, n) reaction induced by bremsstrahlung from an electron
accelerator. Since IPAA uses different nuclear reactions with INAA, IPAA can determine some elements
which INAA cannot determine and is a complementary method to INAA. However, radioactivities of radionuclides produced by (γ, n) reactions induced by bremsstrahlung are difficult to be estimated because
suitable lists of their reaction yields for IPAA users are not available. So we have determined photoneuclear reaction yields to estimate induced radioactivity for IPAA and relative reaction yields to 58 Ni(γ,n)57 Ni reaction were obtained for about 40 elements. Using our relative reaction yields, elemental concentartions are able to be determined by single comparator method, which is a method that elemental
analysis is possible by comparison with one reference element for any elements. Single comparator
method is not so popular in IPAA and relative method, which requires reference elements for all elements to be determined, is usually used to determine. So single comparator method was applied to IPAA
for various samples and an accuracy of the determination by single comparator method was examined.
This mehod is expected to be easy to use for users who are not familiar with activation analysis.

§ 2. Experimental

Four geochemical reference samples (JB-1a, JSO-2, JZn-1, JCu-1) issued by Geological Survey ofJapan (GSJ), two alloys (german silver, stainless steel) and three metals (cobalt, copper, zinc) were
subjected to analysis. About 50 - 70 mg of each powdered sample was taken into a container (10 mmϕ)

108
made of high purity Al foil and it was pressed to make tablet. Several tablets were prepared for eachkind of sample. All samples were put into a quartz tube together with Ni foils(10 mmϕ), which wereplaced at every three or four samples.
Two sets of samples placed in quartz tubes were irradiated for ca. 30 minutes and for ca. 6 hours,
respectively, by bremsstrahlung of maximum end point energy (E0 ) of 20 , 25, and 30 MeV from theelectron linac of the Research Center for Electron Photon Science (ELPH), Tohoku University. After irradiation, produced radionuclides with shorter half-lives in irradiated samples were measured for γ-rays
using HPGe detector at the ELPH as soon as possible. But for long irradiated samples, measurements
were executed at the laboratory of radioisotopes, Tokyo Metropolitan University to detect radionuclides
with longer half-life.
Elemental concentrations were determined by both relative method and single comparator method.
In relative method, concentrations were calculated by comparison between radioactivity in the sample
and one in JB-1a or metal samples. For single comparator method, Ni is the comparator and concentrations (C) were calculated with eq.(1) ;
C=

Mx
rx
Yx
1 − e−λx tAx×
÷ W × 100÷÷÷AN i /wN i
MN i
rN i
YN i
1 − e−λN i t(1)

where, C is elemental concentration in %, A is induced radioactivity, w is mass of element, M is atomic
weight, r is isotopic abundance, Y is reaction yield, λ is decay constant, t is irradiation time, and W is
mass of sample. Subfixs, x and Ni, show the parameter for a sample and Ni monitor, respectively. Yield
ratio, Yx /YN i , determined for about 40 elements by our group [1] was used. Specific activity of 57 Ni,
AN i /wN i , in Ni monitors placed at every a few samples in the quartz tube decreased exponentiallyagainst integrated sample mass [2]. Specific activity of 57 Ni for each sample was calculated by leastsquare method.

§ 3. Results and Discussion

In this report, the results for irradiation by E0 = 20 MeV were reported.
Four samples and two samples were irradiated for JB-1a and the other samples, respectively. De-

termined concentrations were consistent within their uncertainties among four samples or between two
samples. Therefore, correction with Ni monitors for flux variation among irradiated samples in thequartz tube was concluded to be success. And reproducibility of determination by our single comparator
method is good.
Determined elemental concentrations in geochemical reference samples and alloys by the single
comparator method were compared with literature values [3, 4] and concentrations determined by the
relative method, respectively. For example, the ratios of determined concentration value to lirerature
value for some elements are shown in Figs.1 - 6. Determination values of Fe, Na, Ni, Rb, Y and Zr wereconsistent with literature values within ± 10% for all samples. Calcium concentrations were determined by using both 48 Ca (γ, n)47 Ca and 44 Ca(γ, p)43 K reactions. Determined concentrations by 44 Ca(γ,p)43 K reaction were consistent with literature values within ± 10% for all samples. On the other hand,concentrations determined by 48 Ca (γ, n)47 Ca reaction were systematically about 1.5 times higher than

109
literature values for all samples (Fig.1). For Ce, Co, Cu, Mn, Sb, Sr and Zn, the ratios were generally
more than 1.1 and the ratios were generally less than 0.9 for titanium. Especially, the ratios for Cr
and Nb were systematically higher than 1.1, about 1.3 in average. And Ti concentrations for four JB-1asamples are not consistent. Although systematic deviations of concentrations were obtained by the single comparator method for some elements, their concentrations detemined by the relative method wereconsistent with literature values. This consistensy means that induced radioactivity in samples were
produced in proportion to the elemental mass and the correction for the flux variation by our method
using Ni monitors were right. Thus yield ratio values, Yx /YN i , used in calculation with eq.1 for someelements were possibly guessed not to be reasonable and to cause such systematic deviations in thedetermination by the single comparator method. So, yield ratios for concerned elements will be reexamined.
Although the determination value by our single comparator method has a small systematic deviation for some elements at this time, it is concluded that the application of the single comparator method
to IPAA is fundamentally success and our determined yield ratios are reasonable because determined
concentration values by the single comparator method were consistent with literature values or values
by the relative method by -40% to +50% for all elements and for all samples.
2

SampleFig.1. Comparison of the determined concentration values with the literature values for Ca. Calcium concentrations were determined by using
47
Ca and 43 K produced by (γ, n) and(γ, p) reactions, respectively.

Co (3)Co (2)Co (1)

JB-1a(4)JB-1a(3)JB-1a(2)JB-1a(1)

JSO-2(2)0.5

SUS(2)

JZn-1(2)JZn-1(1)JCu-1(2)JB-1a(4)JCu-1(1)JB-1a(3)JB-1a(2)JB-1a(1)

JSO-2(2)

0.5

Ca-47
K-43

1

JSO-2(1)1Co

SUS(1)

Ratio to literature valueCa

JSO-2(1)Ratio to literature value

2

SampleFig.2. Comparison of the determined concentration values with the literature values for Co.

110
2

2

2

Cu(2)

Cu(1)

JCu-1(2)JCu-1(1)

JSO-2(2)JB-1a(4)(b) Zn (Zn-65)

10.5

G.S.(1)
G.S.(2)
JSO-2(1)
JSO-2(2)JB-1a(1)JB-1a(2)JB-1a(3)JB-1a(4)JCu-1(1)JCu-1(2)JZn-1(1)JZn-1(2)Zn

Ratio to literature valueZn

JZn-1(2)

JCu-1

SampleJZn-1(1)

JB-1a

JSO-2

G.S.(3)

G.S.(2)

G.S.(1)

Ratio to literature value

Fig.6. Comparison of the determined concentration values with the literature values for Ti.

(a) Zn (Zn-63)1

0.5

JB-1a(3)SampleFig.5. Comparison of the determined concentration values with the literature values for Nb.

2

1

0.5

JB-1a(4)Sample

JB-1a(3)JB-1a(2)JB-1a(1)

SUS(2)1Ti

JB-1a(2)Ratio to literature value

Nb

SUS(1)

Ratio to literature value

Fig.4. Comparison of the determined concentration values with the literature values for Cu. G.S. means german silver alloy.

JB-1a(1)Fig.3. Comparison of the determined concentration values with the literature values for Cr.

0.5

JSO-2(1)G.S.(3)

G.S.(2)

Sample name

Sample2

G.S.(4)1

0.5

JB-1a(4)JB-1a(3)JB-1a(2)JB-1a(1)

SUS(2)

0.5

SUS(1)1Cu

G.S.(1)

Cr

Ratio to literature value

Ratio to lirerature value

2

SampleFig.7. Comparison of the determined concentration values with the literature values for Zn. (a)63
Zn and (b)65 Zn. G.S. means german silver alloy.

111

Acknowledgment
The authors are indebted to Drs. H. Kikunaga and K. Tsukada, and the operation crew members of
ELPH for their invaluable cooperation and providing excellent beams.

References[1]

Y. Oura et al.: ELPH Annual report (2017) .

[2]

M. Ebihara et al.: J. Radioanal. Nucl. Chem. 244 (2000) 491.

[3]

N. Imai et al.: Geostandards Newsletter 19 (1995) 135.

[4]

S. Okai et al.: Bunseki Kagaku 51 (2002) 973.

ELPH Annual Report, Tohoku University (2018)112(ELPH Experiment : #2898, #2906)

Identification of Elemental Composition and Preparation ofRadio-tracer for Recovery of Rare Metals in Household
Garbage Incineration Slag by Photon Activation Method 2.
K. Akiyama1,∗∗ , K. Takano1 , H. Sugiyama1 , Ahmed S. A. Ali1 , K. Irfan1 ,S. Kubuki1 , and H. Kikunaga2
1

Department of Chemistry, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397

2

Research Center for Electron Photon Science, Tohoku University, Sendai, 982-0826

The composition of the household garbage incineration slag for each month among a year is determined by photon activation method. The homogeneity in the elemental composition among identicalsamples is found to be within 40% in relative standard deviation. The contents of the elements for eachslag sample among a year is found to be slmost constant. Surprisingly, the contents of Cu is found to bealmost same as that of Cu in a chalcopyrite which is the one of the major resource of copper ore.

§ 1. Introduction

Amount of burnable garbage emitted from households is estimated to be about 650 million tons

annually in OECD member countries, and also in japan it is estimated to be about 50 million tons per
year [1]. Although these garbage are usually incinerated and then buried as incineration ashes, there
are same problems, such as securing the site for the burial disposal, because the emissions of theseincineration ashes are enormous. In Tokyo, it is attempted for the improvement of the site problems to
reduce of volume by melting and vitrifying of incineration ash and also to reuse these vitrified ash as
the roadbed materials, the concrete aggregate, and the agent for the soil improvement. [2]Kubuki and co-workers reported the chemical composition of vitrified ash of incinerated household
garbage (incinerated slag) by induced coupled plasma optical emission spectroscopy (ICP-OES) measurements of their nitric acid solution and also the similarity of their composition with aluminosilicate
including iron [3]. It is known that the vitrified solids of aluminosilicate indicate the decomposing abilityof organic materials under the light irradiation [4]. If the incinerated slag of similar chemical composition with aluminosilicate indicates the decomposing ability of organic materials, it is possible to use theincinerated slag for the environmental purification, such as water purification, it could be expected as
the new effective way to use of incinerated slag. However, incinerated slag contains many impurities,
unlike aluminosilicate glass synthesized from the reagents. Since the impurities in incinerated slag include valuable metal elements such as cobalt and manganese, if it is possible to recover these elements
by chemical separation, it will lead to effective use of waste so called ”Urban mine” and also to a solution∗

Correspondence Address: Department of Chemistry, Tokyo Metropolitan University, Hachioji, Tokyo
192-0397

113
to the universal theme in the contemporary society.
In this study, we aim to recover valuable metal elements from incinerated slag and to develop therecovery method by chemical separation. In this paper, we report the validity of chemical composition in
incinerated slag per collecting month in 2018 quantified by photon activation method.

§ 2. Experimental

Approximately 100 mg of incinerated slag collected in Januarly to December, 2018, were powderedwith a handy agate mill. These powdered slag were wrapped in high purity aluminum foil, and thensealed under reduced pressure in a quartz tube for the irradiation with bremsstrahlung. we used JB-1a,
whose elemental composition is quantitatively well assigned in National Institute of Advanced Industrial Science and Technology (AIST) Geological Survey of Japan, and some elemental standard dropped
and dried on a metal foil as the comparative standard for the photon activation analysis. Irradiation
with Bremsstrahlung was carried out at Tohoku University, Research Center for Electron Photon Science (ELPH) under the conditions of maximum electron beam energy of 20 MeV, 0.1 mA. After that, γ
ray emitted from samples were measured with a high purity Ge semiconductor detector (SEIKO EG&G).

§ 3. Results and Discussion

3.1 Homogeneity in the elemental composition among identical samples
In the previous report, we could not have determined some elements because these elements werebasically absent in the JB-1a used as the comparative standard [5]. To improve this situation, it is important to find more optimal standard for this analysis. It can be said to be an effective improvement toemploy a slag sample that has already been quantified for a candidate of a comparative standard material. However, such a slag sample cannot be used for the standard if the homogeneity of the sample is
not guaranteed. For such reason, we individually prepared and irradiated the slag1709 sample for eachbeam time. Table 1 shows the average contents of each element and their relative standard deviation ofslag1709 sample.
Table 1. Average composition and their relative standard deviation (RSD) of slag1709
Element
Ca
Fe
Na
Mg
Ti
Cu*
Mn
Ba
Cr
Zn
Sr
Zr

Contents
g/g
1.980.E-01
6.94.E-02
2.26.E-02
1.82.E-02
1.37.E-02
2.8.E-03
2.38.E-03
1.39.E-03
1.3.E-03
1.1.E-03
5.66.E-03
1.63.E-04

RSD
16.4%
16.2%
9.9%
11.9%
11.3%
23.2%
10.7%
20.5%
7.2%
37.8%
11.2%
10.8%

JB-1a
g/g
6.65.E-02
6.33.E-02
2.03.E-02
4.72.E-02
7.7.E-03
5.67.E-05
1.15.E-03
5.04.E-04
3.92.E-04
8.21.E-05
4.42.E-04
1.44.E-04

Element
Ni
Co
Ce
Nb
Y
Rb
Mo
Sc
Sb
Cs
Au*

Contents
g/g
5.3E-05
3.89E-05
3.01E-05
2.33E-05
1.62E-05
9.65E-06
1.57E-05
5.6E-06
3.1E-06
5.3E-071.858E-07

RSD
40.0%
8.0%
17.1%
11.6%
12.2%
9.3%
34.1%
13.8%
26.1%
29.6%

JB-1a
g/g
1.39E-04
3.86E-05
6.59E-05
2.69E-05
2.4E-05
3.92E-05
1.57E-06
2.79E-05
2.5E-07
1.31E-06
7.1E-10

114
The determined value of astarisk marked elements was basically quantified not from JB-1a but fromthe comparation of solution standard because the contents of these elements in JB-1a were not enoughfor the quantitation by photon activation alanysis. The contents of Au is found to be not homogeneous
because γ-ray peak of 196 Au, which is used for the determinatin of Au, is sometimes absent in theobtained γ-ray spectra of this slag samples. Except for these element, there are some elements whose
contents is difficult to determine, such as Mo, and Sb, becouse of their contents in JB-1a being extremely
lower than those in Slag samples. For the use of this slag sample for the comparative standard, it is foundthat it is required to quantitate the amount of these elements precisely.
3.2 Variation in composition of slag during a year
Figure 1 shows the contents of each element determined by photon activation analysis (PAA) dureling a year. The contents of some elements, such as Ce, Mo, and Au, are found to be dispersed but thoseof other elements are basically almost constant. From the view point of resource recovery, it is desirable
that the amount of the elements is stablely constant in slag. Surprisingly, contents of Cu is found tobe almost same as that of Cu in a chalcopyrite which is the one of the major resource of copper ore. In
addition, it is found that The contents of Mo and Au are exceeded the abundance in the earth’s crustof these elements. Considering about the availability of resources, Household garbage incineration slag
may be a useful resource as an urban mine in the future.

Fig.1. Contents of each element determined by PAA for each month.

115

Acknowledgment
We deeply thank to the facility staffs of research center for electron photon science at Tohoku University for supplying the high-quality electron beam. And also we thank to Doctor Kyo Tsukada for
helping us in the sample irradiation. This work was supported by Tokyo Metropolitan Government
Advanced Research Grant Number (H29-1).

References[1]OECD, “ Municipal Waste ”, in OECD Factbook 2015-2016: Economic, Environmental and Social
Statistics, OECD Publishing. DOI: 10.1787/factbook-2015-en (2016).

[2]

Waste Report ed. Clean Authority of Tokyo, (2018) vol. 23, p. 7.

[3]

S. Ishikawa, B. Kobzi, K. Sunakawa, S. Nemeth, A. Lengyel, E. Kuzmann, Z. Homonnay, T.
Nishida, S. Kubuki, Pure Appl. Chem., 89, 535 (2017).

[4]

Y. Iida, K. Akiyama, B. Kobzi, K. Sinkó, Z. Homonnay, E. Kuzmann, M. Ristić, S. Krehula, T.
Nishida, S. Kubuki, J. Alloys Compd., 645, 1 (2015).

[5]

K. Akiyama, K. Ito, S. Kubuki, H. Kikunaga, ELPH Annual Report (2017) 117.

ELPH Annual Report, Tohoku University (2018)116(ELPH Experiment : #2904)

Development of simultaneous production method for
carrier-free RI multitracer of potassium, rubidium andcesium
H. Ikeda1,2∗ , H. Kikunaga2 , and H. Watabe1
12

Cyclotron and Radioisotope Center, Tohoku University, Sendai, 980-8578

Research Center for Electron Photon Science, Tohoku University, Sendai, 982-0826

We developed a method for producing carrier-free RI tracers of potassium, rubidium, and cesium
using photonuclear reactions with an electron linear accelerator in the Research Center for Electron
Photon Science (ELPH), Tohoku University. And these RIs have been supplied to researchers in Japan.
In this study, our purpose was the development of simultaneous production method for the carrier-free
RI multitracer mixed potassium, rubidium and cesium.
The radioisotopes of potassium, rubidium and cesium were produced by irradiating bremsstrahlung,which was generated by an electron linear accelerator of ELPH, to calcium oxide, strontium oxide andbarium oxide. After mixing the three irradiated targets, the radioisotopes of the alkali metals wereseparated from the target materials by an oxalate precipitation method, and were purified by cationexchange column chromatography. The yield of radioisotopes in the precipitation method and column
chromatography was determined by gamma spectrometry using a high purity germanium detector.
We demonstrated that carrier-free RI multitracer of potassium, rubidium and cesium can be purified by chemical separation simultaneously. The yield of chemical separation was about 85-90% for eachalkali metal tracer. The loss of them was mostly due to the precipitation method.

§ 1. Introduction

The behavior of alkali metal elements, sodium (Na), potassium (K), rubidium (Rb) and cesium (Cs)in plants have been interested. Especially, K is an essential plant element, and demand for 42 K (T 1/2= 12.4 h) and 43 K (T 1/2 = 22.3 h) is increasing as its radioisotope (RI) tracer. However, RIs of K cannot be purchased because they are short-lived nuclides with half-lives of less than 1 day, except for 40 K
(T 1/2 = 1.28 × 109 y). We developed that production method of 42,43 K tracers by bremsstrahlung irradi-

ation of nat CaO target using electron linear accelerator of Research Center for Electron Photon Science(ELPH), Tohoku University. A method of chemical separation of carrier-free K tracers from the target
was reported (Fig. 1) [1]. On the other hand, Na, Rb and Cs are available for purchase however arevery expensive. We have also developed of production for carrier-free RI tracer of Rb and Cs by the similar method from K tracer. If they can be produced and separated at the same time as K, experiments∗

Cyclotron and Radioisotope Center, Tohoku University, Sendai, 980-8578

117with three elements can be performed simultaneously. This is expected to make the studies of element
dynamics in plants more efficient.
In this study, we researched the production possibility of a mixed sample of K, Rb, and Cs as a multitracer of alkali metal elements. Since each element has similar properties, it is reasonable to performchemical operations at the same time. It needs to investigate the radioactivity of Rb and Cs tracers
produced by the similar method to production of 42,43 K tracers. Rb and Cs tracers were produced bybremsstrahlung irradiation with nat SrO and nat BaO, respectively. The conditions of chemical separation were researched by the method improved (Fig. 1) [1]. The RIs measured were 42 K (T 1/2 = 12.4 h),
43

K (T 1/2 = 22.3 h), 83 Rb (T 1/2 = 86.2 d), 84 Rb (T 1/2 = 32.8 d), 86 Rb (T 1/2 = 18.6 d), 132 Cs (T 1/2 = 6.48 d) and136

Cs (T 1/2 = 13.2 d).

Fig.1. Chemical procedure for the preparation of carrier-free 42,43 K tracer. nat CaO was added
water and oxalic acid, and Ca2+ is precipitated as calcium oxalate (CaC2 O4 ). The supernatant is charged into the cation exchange column (1 mL). The column is flushed by 10
mL of 0.01 M HCl to remove impurities. It is flushed 10 mL of 1.5 M HCl, and K tracer iseluted.

§ 2. Experiment

Powdered nat CaO, nat SrO or nat BaO were pressed into pellets. The pellets and nickel (Ni) foils

were sealed in a T-shaped quartz tube replaced with helium gas. The component of sealed pellets wasoxide of a single element. This tube was irradiated in the #1 Experiment Room of ELPH. The target tube
behind the three of 1 mm thickness tantalum plates was irradiated by electron beam while cooling withwater. The energy of electron beam was 50 MeV, beam current was 20 µA, and irradiation time was 30
minutes.
The radioactivity of alkali metals, 42 K, 43 K, 83 Rb, 84 Rb, 86 Rb, 132 Cs and 136 Cs, in the targets and solutions were measured by a high purity germanium detector. 47 Ca (T 1/2 = 4.54 d), 83 Sr (T 1/2 = 32.4 h) and135m

Ba (T 1/2 = 28.7 h) produced simultaneously with alkali metal RIs were also measured. In addition,

118
57

Ni (T 1/2 = 35.6 h) produced by irradiation of Ni foils were measured for correction of radioactivity ofalkali metals [1, 2].
The pellets of nat CaO, nat SrO and nat BaO were placed into the same tube, and water was added.
The aqueous solution of oxalic acid (H2 C2 O4 ) was added to precipitate as oxalate salts (CaC2 O4 , SrC2 O4and BaC2 O4 ). The supernatant was charged onto a cation exchange column. The eluent was concenR
50WX8 100-200
trated hydrochloric acid (conc. HCl), and the elution curve was drawn. Muromac⃝
R
Mini-column
mesh was used as a cation exchange resin. 2 mL of the resin was filled into the Muromac⃝(size M). This column was flushed with 20 mL of H2 O, 20 mL of conc. HCl 20 mL and 20 mL of 0.01 M
HCl in a sequential order for conditioning.

§ 3. Results

Table 1 shows the productions of 42,43 K, 83,84,86 Rb, and 132,136 Cs corrected by the radioactivity of 57 Ni

in the Ni foils. From this data, about 620 mg of nat CaO is required to produce 10 MBq of 43 K if theelectron beam conditions are 50 MeV and 120 µA. Similarly, we found that about 400 mg of nat SrO was
required to produce 1 MBq of 86 Rb, and about 740 mg of nat BaO was needed to produce 1 MBq of 136 Cs.
Table 2 shows the radioactivity of alkali metal RIs co-precipitated in oxalate. Every RI showed a lossof about 10-15%. When purifying the alkali metal tracer by our proposed method, it should be notedthat the yields of the alkali metal RIs in supernatant are 85-90%. The elution curve is shown in Fig.
2. Almost all alkali metals were eluted in about 2 column volumes. No radioactivity of alkaline earth
metal RI (47 Ca, 83 Sr and 135m Ba) was observed in the eluent. Thus, a method for chemical separation of
three alkali metal RIs (42,43 K, 83,84,86 Rb and 132,136 Cs) has been established.
Table 1. Prodution yields of alkali metal RIs.
RI
K
43
K
83
Rb
84
Rb
86
Rb
132
Cs
136
Cs
42

Yield (Bq/mg/µA/h)
21.0 ± 2.3
45.1 ± 4.2
0.582 ± 0.109
0.498 ± 0.034
6.93 ± 0.91
0.362 ± 0.112
3.77 ± 0.93

Table 2. Co-precipitated ratios of alkali metals RIs.
RI
K
43
K
83
Rb
84
Rb
86
Rb
132
Cs
136
Cs
42

co-precipitated (%)
11.9 ± 1.0
14.6 ± 1.6
12.3 ± 8.0
14.3 ± 5.2
15.6 ± 3.2
12.8 ± 5.5
9.0 ± 2.6

119

Fig.2. Elution curves of cation exchange chromatography for alkali metals (43 K, 86 Rb and 136 Cs)
and target elements (47 Ca, 83 Sr and 135m Ba). Conc. HCl was used for eluent. 100% is thetotal radioactivity in the charged solution.

References[1]

H. Kikunaga et al.: ELPH Annual Report (2015) 105.

[2]

H. Kikunaga et al.: ELPH Annual Report (2014) 144.

ELPH Annual Report, Tohoku University (2018)120(ELPH Experiment : #2914)

Investigation of optimal thicknesses of W converters inelectron linac production of 99Mo
Jaewoong Jang1 , Hidetoshi Kikunaga2 , Shun Sekimoto3 , Makoto Inagaki3 ,Tomohiko Kawakami4 , Tsutomu Ohtsuki3 , Shigeru Kashiwagi2 ,Ken Takahashi2 , Kyo Tsukada2 , and Mitsuru Uesaka1,5
1
2Department of Bioengineering, University of Tokyo, Bunkyo, Tokyo 113-8656, Japan

Research Center for Electron Photon Science (ELPH), Tohoku University, Sendai, Miyagi
982-0826, Japan

3

Institute for Integrated Radiation and Nuclear Science, Kyoto University (KURNS), Sennan,
Osaka 590-0494, Japan
4
5

Kaken Inc., Mito, Ibaraki 310-0903, Japan

Nuclear Professional School, University of Tokyo, Naka, Ibaraki 319-1188, Japan

Increasing the specific yield of 99 Mo is one of the most important tasks in realizing accelerator
production of 99 Mo. In this study, we attempt to increase the specific yield of 99 Mo through adjusting the
thicknesses of tungsten converters. A series of Monte Carlo simulations was performed, and the results
were validated by irradiation experiments.

§ 1. Introduction

Technetium-99m (99m Tc), the most widely used radionuclide in nuclear medicine, is obtained throughgeneration from the decay of molybdenum-99 (99 Mo). For decades, 99 Mo has been produced via the fission of enriched uranium-235 (235 U) in research reactors. As most of the 99 Mo production reactors willneed to shut down in about 10 years (Fig. 1 [1]), alternative methods of 99 Mo/99m Tc production need to
be developed. A promising alternative is to produce 99 Mo via the 100 Mo(γ,n)99 Mo reaction, where thehigh-energy photons (γ) are generated using an electron linear accelerator (linac).
One of the key issues in electron linac production of 99 Mo is to increase the yield and specific yield of99

Mo. Several approaches are available, among which adjusting the thickness of tungsten (W) converters

is relatively simple and practical. In order to investigate such optimal W thicknesses, we performed
Monte Carlo (MC) simulations and experimentally validated the calculation results.

§ 2. Calculation
2.1 Theory

The production yield of 99 Mo can be expressed as [2]YMo-99 (tirr ) = [1 − exp(−λMo-99 tirr )] VMo-tar ρMo-100 Ie−

 ∞

Eγ,th

ΦMo-tar (Eγ ) σ (Eγ ) dEγ ,

(1)

121

Remaining yearsof operation

OPAL(Australia)

2007−2057
38 y

Maria

1974−2030(Poland)

11 y

Osiris1966−2015(France)

SAFARI−1

1965−2030(S. Africa)

11 y

BR−2

1962−2026(Belgium)

7y

HFR

1962−2026(Netherlands)

7y

LVR−151957−2028(Czech Rep.)

9y

NRU

1957−2018(Canada)

2019
1950

1975

2000

2025

2050

2075

Year
Fig.1.

Operation years of 99 Mo production reactors

where λMo-99 is the decay constant of 99 Mo, tirr the irradiation time, VMo-tar the volume of a Mo target,

ρMo-100 the mass density of 100 Mo, Ie− the electron beam current, Eγ = Eγ (Ee− ) the photon beamenergy, ΦMo-tar (Eγ ) the photon fluence in the Mo target, and σ (Eγ ) the excitation function for the100

Mo(γ,n)99 Mo reaction. Eq. (1) shows that by increasing ΦMo-tar (Eγ ), the 99 Mo yield can be increased

without having to change beam parameters and irradiation conditions. In this study, we attempt toincrease ΦMo-tar (Eγ ) by adjusting the W converter thicknesses.
2.2 Parametric simulations
2.2.1 Initial simulation runs
To simulate various W thicknesses with different beam energies, MC simulations were performed
using PHITS v3.02 [3] and EGS 5, with phitar [4] used as the frontend program. phitar is a PHITS
wrapper program that we developed to perform multivariate simulations [5]. The simulation conditions
were as follows.
• Electron beam size: 4.5 mm in full width at half maximum (FWHM), Gaussian• Electron beam energy: 20–50 MeV, monoenergetic• W thickness: 1.0–7.0 mm• MoO3 target: 5 mm in thickness and 10 mm in diameter• Distance between W and MoO3 : 13 mm

Some of the photon tracks calculated for Ee− = 50 MeV are shown in Fig. 2 and Fig. 3 [5]. Based on thesimulation results, we conducted irradiation experiments using the high-intensity electron linac at the
Research Center for Electron Photon Science (ELPH), Tohoku University.

122
W thickness: 1.0 mm

W thickness: 4.0 mm

10−1x (mm)

Aumet

0
Almet

10−2

MoO3

−20

Wmet

−20

0

20

40

20
Aumet

10−3

0
Almet

Photon tracks calculated for a 1-mm W
converter

10−2

MoO3

−20

−20

z (mm)

Fig.2.

10−1

Aumet

Wmet

0

20

40

Monte Carlo fluence (cm-2 electron-1)

Aumet

x (mm)

20

100
Monte Carlo fluence (cm-2 electron-1)

100

10−3

z (mm)

Fig.3.

Photon tracks calculated for a 4-mm W
converter

2.2.2 Simulation reruns
The dimensions of targetry materials and beam sizes used in experiments differed from the conditions explained above. Therefore, we performed again MC simulations, now with respect to the actual
experimental conditions.

§ 3. Experimental
3.1 Outline

For respective electron beam energies out of 20, 35, and 50 MeV, three W converters having different
thicknesses were investigated. A set of a MoO3 target and Au foils was placed at the downstream sideof a W converter for each irradiation run (Fig. 4(C)). In this targetry configuration, the W thickness at
which the greatest 99 Mo and 196 Au activities are induced can be considered the optimal W thickness forthe beam energy in question.
3.2 Materials
W plates having nominal thicknesses of 0.5–2 mm and Au foils of 50 µm in thickness were purchased(Nilaco Corp., Japan). W thicknesses were adjusted by combining the W plates of different thicknesses.
On the other hand, we directly prepared MoO3 targets by sintering nonenriched MoO3 powder (Kojundo Chemical Laboratory Co., Ltd., Japan) using a pulsed electric current sintering (PECS) machine(SPS1050, Izumi Technology, Japan).
Finally, the MoO3 targets and pairs of Au foils were wrapped with 12-µm thick aluminum foils.
These target materials were then placed on an order-made target holder. The target holder was designed
such that the W thickness can be adjusted (Fig. 4(C)).

123

(a)

(b)

BeO
fluorescent screen

Beam exit
Target holder(c)
W converter
MoO3 target

Fig.4.

(a) Adjusting the position of target holder using laser. (b) Adjusting the irradiation centerusing a BeO fluorescent screen. (c) Targetry set up for irradiation

3.3 Irradiation and gamma-ray spectrometry
The W converters were irradiated with electron beams of 20, 35, and 50 MeV. The detailed irradiation conditions are summarized in Table 1 [5].
After the irradiation, the 99 Mo and 196 Au activities were measured using germanium detectors. The
MoO3 targets were dissolved in 6-M NaOH(aq) prior to the gamma-ray spectrometry. On the other hand,no preprocessing was performed on the Au foils. The units of the measured activities were adjusted to
kBq g−1 µA−1 , so that the different target masses and different beam currents (Table 1) do not affect theactivity comparison.
Table 1. Irradiation (Irr.) conditions. The symbols σh and σv denote the horizontal and vertical
Gaussian beam sizes, respectively
Beam energy
(MeV)
20
35
50

Irr. No.
1
2
3
4
5
6
7
8
9

Beam size (mm)
σv
σh
10.8

3.2

4.4

4.8

4.8

2.5

Average beam current(µA)
15.8±1.7
15.7±1.4
17.1±0.417.7±0.3
18.1±1.2
18.7±0.4
19.4±0.6
20.3±0.5
20.7±0.5

Irradiation time
(min)
10
5
5

Mo specific activity (kBq g−1 uA−1)

40

99

124

0

20 MeV, nps 1e7
20 MeV, nps 1e8
20 MeV, meas 1
20 MeV, meas 2

30

20

10

0

0.5

1.0

1.5

2.0

2.5

3.0

W thickness (mm)Fig.5.

Calculation and experimental results of 99 Mo specific activities as functions of W thickness. The electron beam energy was 20 MeV§ 4. Results and discussion

The specific activities of 99 Mo for Ee− = 20 MeV and Ee− = 35 MeV are plotted in Figs. 5 and 6,

respectively. For these beam energies, the optimal W thicknesses were in agreement between the calculation and experimental results:• The greatest 99 Mo specific activity for Ee− = 20 MeV was calculated to be 12.91 kBq g−1 µA−1 at theW thickness of 1.48 mm• The greatest 99 Mo specific activity for Ee− = 20 MeV was measured to be 6.14 kBq g−1 µA−1 at theW thickness of 1.48 mm• The greatest 99 Mo specific activity for Ee− = 35 MeV was calculated to be 26.80 kBq g−1 µA−1 at theW thickness of 2.58 mm• The greatest 99 Mo specific activity for Ee− = 35 MeV was measured to be 32.29 kBq g−1 µA−1 at theW thickness of 2.58 mm

On the other hand, the specific activities of 99 Mo for Ee− = 50 MeV (Fig. 7) differed between thecalculation and experimental results:• The greatest 99 Mo specific activity for Ee− = 50 MeV was calculated to be 50.50 kBq g−1 µA−1 at theW thickness of 3.16 mm• The greatest 99 Mo specific activity for Ee− = 50 MeV was measured to be 52.25 kBq g−1 µA−1 at theW thickness of 2.13 mm

The differences are attributed to the following factors.
• Beam energy spread. In the MC simulation runs, monoenergetic electron beams were transported.
In the irradiation experiments, however, the electron beams exhibited energy spread. Electron

beams having unintended energies could result in photons of different energies, which could inturn affect the yield of the 100 Mo(γ,n)99 Mo reaction.
• Beam current fluctuation. The average beam currents shown in Table 1 are actually the means

Mo specific activity (kBq g−1 uA−1)

60

99

125

20
1.0

35 MeV, nps 1e7
35 MeV, nps 1e8
35 MeV, meas 1
35 MeV, meas 2

50

40

30

1.5

2.0

2.5

3.0

3.5

4.0

4.5

W thickness (mm)Fig.6.

Calculation and experimental results of 99 Mo specific activities as functions of W thickness. The electron beam energy was 35 MeV

Table 2. The calculated and experimental 196 Au specific activities of upstream Au foils
Beam energy (MeV)
20

35

50

W thickness (mm)
0.45
1.48
2.53
1.48
2.58
3.61
2.13
3.16
4.21

196

Au specific activity (kBq g−1 µA−1 )Calculation
Experimental
61.29
104.3497.85
180.65210.60202.07365.18395.38381.27

33.84
74.08
65.77
193.51
248.18234.23275.15366.92245.56of average beam currents measured over irradiation times. As can be seen from the standard
deviations in Table 1, some of the irradiation runs were accompanied by beam current fluctuations,which could affect the absolute values of experimental 99 Mo specific activities.
The 196 Au specific activities of the upstream Au foils are summarized in Table 2, and those of thedownstream Au foils in Table 3. The W thicknssess leading to the greatest 196 Au specific activities were
the same between calculation and experimental results in the upstream Au foils, but not in the downstream Au foils. Considering the overall agreement in the upstream Au foils and the overall discrepancy
in the downstream Au foils, it is thought that the beam interactions within the MoO3 targets could affectthe 197 Au(γ,n)196 Au reactions in the downstream Au foils.

§ 5. Summary

To improve the 99 Mo production yield, we investigated optimal W thicknesses for electron beamenergies of 20, 35, and 50 MeV. The calculated results were compared with experimental results, andMo specific activity (kBq g−1 uA−1)

80

99

126

40
1.5

50 MeV, nps 1e7
50 MeV, nps 1e8
50 MeV, meas 1
50 MeV, meas 2

70

60

50

2.0

2.5

3.0

3.5

4.0

4.5

5.0

W thickness (mm)Fig.7.

Calculation and experimental results of 99 Mo specific activities as functions of W thickness. The electron beam energy was 50 MeV

Table 3. The calculated and experimental 196 Au specific activities of downstream Au foils
Beam energy (MeV)
20

35

50

W thickness (mm)196

Au specific activity (kBq g−1 µA−1 )Calculation
Experimental

0.45
1.48
2.53
1.48
2.58
3.61
2.13
3.16
4.21

85.21
84.93
75.31
178.01
175.05
159.64340.84333.38308.48

46.47
54.00
51.39
194.06204.45190.07129.33300.21
324.15the overall results of MoO3 targets and upstream Au foils agreed between calculations and experiments.
The agreeing W thicknesses of the MoO3 results for 20 MeV and 35 MeV, together with the acceptably small differences in the overall calculation and experimental results, suggest that the parametriccalculations of the optimal W thicknesses can be valid.
However, it should be noted that the above results hold only for the intertarget distance of ourtarget holder, or 13 mm, and for the beam sizes used in the experiments (Table 1): for a different set of
an intertarget distance and a beam size, the contributions of photon tracks are modified, and so is thebalanced W thickness. Our program phitar can be used in such cases, which can calculate targetry- andbeam-specific optimal thicknesses of converter materials.

Acknowledgments
We are grateful to K. Tatenuma and Y. Natori (Kaken) for helping the preparation of MoO3 targets,and to Y. Inoue (UTokyo) for experimental assistance. We would also like to express our gratitude to the127
ELPH staffs for the operation of the high-intensity electron linac.

References[1]

Jaewoong Jang and Mitsuru Uesaka. Influence of enriched 100 Mo on Mo reaction yields. Journalof Physics Communications, 3(5):055015, 2019.

[2]

Jaewoong Jang, Masashi Yamamoto, and Mitsuru Uesaka. Design of an X-band electron linear
accelerator dedicated to decentralized 99 Mo/99m Tc supply: From beam energy selection to yield
estimation. Physical Review Accelerators and Beams, 20(10):104701, 2017.

[3]

Tatsuhiko Sato, Yosuke Iwamoto, Shintaro Hashimoto, Tatsuhiko Ogawa, Takuya Furuta, Shinichiro Abe, Takeshi Kai, Pi-En Tsai, Norihiro Matsuda, Hiroshi Iwase, Nobuhiro Shigyo, Lembit
Sihver, and Koji Niita. Features of particle and heavy ion transport code system (PHITS) version
3.02. Journal of Nuclear Science and Technology, 55(6):684–690, 2018.

[4]

Jaewoong Jang. phitar - A PHITS wrapper for targetry design (v1.03), 2019. Zenodo.

[5]

Jaewoong Jang. Parametric analyses in electron linac production of 99 Mo/99m Tc. PhD thesis,
University of Tokyo, Tokyo, Japan, 2019.

III. Status ReportELPH Annual Report, Tohoku University (2018)

129

Status of Accelerator Facilities in FY2018
F. Hinode, K. Kanomata, S. Kashiwagi, S. Miura, T. Muto, I. Nagasawa,
K. Nanbu, Y. Shibasaki, K. Takahashi, H. Hama
Accelerator group in ELPH, Tohoku University, Sendai, 982-0826

The total operating time of the electron accelerator complex; high intensity 60 MeV linac, 90 MeV
injector linac and 1.3 GeV BST (booster-storage ring) exceeded 2000 hours in FY 2018, including theoperation of the test accelerator t-ACTS. While the machines had stably operated during the user’s time,some upgrade works for the accelerator complex were also conducted, such as a replacement of rf powersource for BST, improvements of beam line and irradiation system for the high intensity linac, etc. In
this article, status and some improvements of accelerator complex are reported.

§ 1. High intensity linac

The electron beam from the high intensity linac was supplied with the energy range of 10-60 MeV

depending on a requirement of individual machine user. The typical beam current was 120 µA for 50
MeV operation. The operating beam time of the high intensity linac in FY 2018 exceeded 340 hours.
On the summer shutdown in 2018, upgrade work of the beam transport line was carried out. Construction of new beam line for an experiment of electron scattering with extremely low energy transfer(ULQ2) was also started partially. Originally beam tuning in the high-intensity linac had been extremely
difficult due to the lack of properly installed beam monitors and focusing magnets. To improve this, 8
quadrupole magnets and orbit correction magnet were newly added or replaced to the appropriate locations, as well as two profile monitors. Figure 1 shows a schematic layout of the entire beam line after the
upgrade work. Figure 2 also shows pictures of the beam transport line before and after the installationof new magnets. Although the beam transmission seems to have been improved by this upgrade work,
further study is underway.
In this summer shutdown, upgrade of irradiation system was also conducted [1]. Before the upgrade, the converter for gamma rays had been installed in the irradiation pool together with the sample
target, but it was changed to separated structure. This modification was intended to increase the yield of
gamma rays by bringing the irradiated sample closer to the electron beam extraction window. Furthermore, it was also expected to reduce the exposure during the exchange work of sample target. By thisimprovement in addition to the upgrade of beam transport line, the yield of produced RI was enhanced
by 6.5 times comparing with the previous irradiation with 20 MeV. Figure 3 shows the 3D model andpicture of new irradiation system.
Although the linac was operating almost stably in this year, there were some troubles. So far, linac
operation has been frequently suspended due to the trouble, so-called “vacuum explosion”, in which the

130

Fig.1.

Schematic layout of the entire beam line after the upgrade work. QF4L, QD4L are newly
added to the end of linac. Two doublets QD2B, QF2B and QF4B, QD4B are replaced withnew magnets, while a doublet QF3B, QD3B and steering magnet Sxy2B are newly addedin the beam transport line.

Fig.2.

Before (left) and after (right) the installations of new magnets in the beam transport line.

131

Fig.3.

3D model (left) and picture (right) of the new irradiation system.

vacuum pressure of beam line suddenly increases and finally results in the trip of ion pumps. As thefrequency of explosions increased, vacuum leak hunting was carried out again for the entire beam line.
As a result, there were two small leaks; one was found at a small crack on the beam window, and theother one was located at the flange part in front of the ULQ2 dipole magnet. After this leak hunting,the frequency of explosions has decreased significantly for a while. However, recently it has begun tooccur again, although it is less frequent. Since the ion pump itself is presumed to be degraded, some ion
pumps with high base pressure will be replaced during the next summer shutdown.
The old electron gun has been also problematic, because the cathode is no longer supported bysupplier. Currently installed cathode has been operated more than 10 years and still working with anominal emission current of 300 mA. At present, new spare cathode is no longer in stock, so we arepreparing a new replaceable electron gun based on EIMAC Y646B. The installation of the new electron
gun will be implemented during the long shutdown period next summer after testing the electron gun
on the test bench.

§ 2. Injector linac

The injector linac stably supplies an electron beam to the BST ring with energy of 90 MeV. However,there is a problem with recent thermionic rf guns, that discharges has been starting to occur in the
gun cathode cells about a year after the installation of the new cathode. Currently, this problem iscoped by replacing the cathode once a year. It is known that the reason for the discharge is due to theunusual deposition of carbon-like material between the cathode and the cavity wall, but the cause forthe deposition is currently under investigation.

§ 3. BST ring

1.3 GeV BST ring has well operated to generate high energy gamma rays via bremsstrahlung frominternal target wire inserted to the electron beam orbit. Generated gamma rays are not only utilized tothe experiment for quark/hadron physics, but also supplied to the test beam line for testing of detectors
used in high energy experiments.

132
For the klystron high-voltage power supply in BST, the effects of aging over 20 years after production had been concerned. In fact, in 2017, there was a trouble that an IGBT in one of the ten high voltage
units was damaged during operation. This IGBT was no longer supported and it was impossible to geta replacement, so it had been forced to work with 8 units. In addition, the impact of recent increases
in the unit price of electricity and also in the cost of heavy oil for air conditioning equipment is serious,
getting to make it difficult to secure a budget for operating the facility accelerator. In particular, theuse of klystron (E3774, Toshiba Corp.) transferred from KEK-PF was inefficient. Because 10 kW wasenough for the current user even though it was possible to output large power of 100 kW level. This
year, therefore, we decided to replace the klystron with a low-power solid-state amplifier. The maximum
output power was set to 15 kW in anticipation of a future increase in circulating beam current. Table 2
shows the specifications of the rf amplifier (CA500BW1-7272R, RandK Co. Ltd.).
Table 1. RF power amplifier, CA500BW1-7272R

Frequency Range
Output Power
Gain
Gain Flatness
Harmonics
Spurious
Return Loss
Power Dissipation

Specification @500 MHz
500±0.5MHz
15 kW @P2dB/CW+72 dB (min.)
0.5dB (max.)-30dBc (max.)-70dBc (max.)-14dB (max.) input-10dB (max.) output
38kVA (max.)

Measured15.5 kW+73.17 dB±0.01dB-41.83dBc<-80.00dBc-24.21dB-19.84dB
31.5kVA

To keep costs down, the frequency band was set to 500 ± 0.5 MHz. It is configured to output the rated

power by combining the module of the amplifier unit using LDMOS. The output of the driver amplifier
is divided into 6 ports, each of which is input to the 4-channel amplifier unit and amplified to about 700
W per channel. After that, the outputs of 6 amplifier units (24 channels in total) are combined withthe radial combiner to output a total power of 15kW in maximum. The RF power finally output fromthe WX-77D coaxial tube is converted into a WR-1500 waveguide and then supplied to the accelerating
cavity through the existing microwave circuit. Each channel in the amplifier unit has a circulator toprotect against reflected power. In addition, if only the final stage amplifier fails, operation can continue
within the scope of redundancy. Figure 4 shows the new RF power souce installed in March, 2019. Allelements are housed in a 2 m high rack and the entire system is very compact. By replacing to thisnew RF source , the electric power required for operation was reduced by 180 kW as expected. This isequivalent to about 15% of the electricity power contracted this year.

133

Fig.4.

New RF power souce installed to BST.

References[1]

K. Takahashi et al., Proc. of the 15th Annual Meeting of Particle Accelerator Society of Japan,
p.688, (2018)

ELPH Annual Report, Tohoku University (2018)134

User Support Ofﬁce Report in FY2018
M. Miyabe1 and the user support ofﬁce1
1

Research Center for Electron Photon Science, Tohoku University, Sendai, 982-0826, JapanThe User Support Ofﬁce coordinate across the users and our facility for management of the beamtime. In 2018 ﬁnancial year, we had provided the electron, photon and positron beam without apparent
problems except for Photon beamline I. In May 2018, because the failure of the accelerator has occurred,
we couldn’t provide any user beam-time because of the repairing work about one month.

§ 1. Introduction

ELPH has three accelerators for Joint Usage/Research. Our facility could provide several beams

with following three beam lines,• 70 MeV electron linear accelerator (linac) at the ﬁrst irradiation lab (For Radiochemistry)• Tagged photon beam from 1.3 GeV electron synchrotron called BST ring with 90 MeV injector at
the second irradiation lab (For Hadron Physics, Photon beamline I)• Tagged photon beam at the GeV-γ irradiation room (For Hadron Physics, Photon beamline II)

In addition, positron/electron beam line for testing detectors is located at the GeV-γ irradiation room.
The 70 MeV electron linear accelerator was utilized for the Radiochemistry experiments by photonuclear reactions. It could produce radio active source with its high intensity. Both tagged photon
beam line was used for Hadron physics experiments. NKS2 and FOREST/BLC experiment have bean
held in recent years.

§ 2. Beamtime operated

The total radiation time was 300 hours for the RI linac operation and 1627 hours for the BST

operation, and it was 1927 hours in total. Table 1 summarizes the radiation times, and user beam times
in ﬁscal.
Many experiments for testing detectors were made by positron beam line. Positron beam was produced by bremsstrahlung photon beams from the synchrotron. Total 26 shifts experiments are performed
using this positron beam in this ﬁnancial year.
A Next generation FOREST experiments (FOREST/BLC) was started by GeV-γ group in ELPH.
New bending magnet was installed on the downstream of FOREST detectors and it covers the mostforward angle. These new experimental setup enable the zero degree proton detection for the γd → pηnreaction at Eγ ∼ 0.9 GeV. This reaction gives the zero relative momentum between the η and n. Thissituation will enable to determine the ηn scattering length. In this ﬁnancial year, physical data was135taken with hydrogen and deuteron target. Total 76 shifts of FOREST/BLC experiment were carried out
and are equivalent to 1/3 of its goal.
In Photon beam line I, New detectors research and developments for NKS2 experiment has been carriedout in this ﬁnancial year.
one experiment was carried out for the undergraduate students. this experiment (#2899: H. Ohnishi,
ELPH, Tohoku University) is for the education of the undergraduate students in ELPH.
Table 1. Radiation times, and user beamtimes in ﬁnancial year 2018. They are given by the sumof the times that the beam is coming to the beamline, and that the beam is provided tothe users.
RI Linuac
BST Ring
radiation (h) radiation (h)
Month
April
23
142
37
90
May
35
531
Jun
29
2
July
0
0
AugustSeptember
0
0
32
457
October
44
202
November
27
94
December
31
89
January41
0February
March
0
26
Sum
300
1627

§ 3. ELPH workshops and ELPH seminars

In this ﬁscal year, ELPH supported four ELPH workshops. The ﬁrst one is hadron physics (C023:

H. Nagahiro, Nara Women’s University), the second one is SNP school 2018 (C022: S. N. Nakamura,Tohoku University), the third one is nuclear physics (C021: T. Suda, ELPH Tohoku University).
17 ELPH seminars were held in this ﬁscal year. Seminars title and talker are listed below.
• Michael Kohl, 米国・ハンプトン大, ”Anomalies in proton observables - old physics or new physics?”• 吉田 純也, 原研先端研, ”ダブルハイパー核検出実験 J-PARC E07 と原子核乾板技術の現在”• 谷田 聖, 原研先端研, ”スピン偏極で見るバリオン構造”• 中川 格, 理化学研究所, ”RHIC における高エネルギー横偏極陽子＋陽子衝突の超前方π 0 生成左右非対称性と陽子のスピンパズル問題”• Alessandro Scordo, イタリア、INFN-Frascati 研究所, ”SIDDHARTA-2 experiment at DAFNE: readyfor the ﬁrst measurement of kaonic deuterium（on behalf of SIDDHARTA & SIDDHARTA-2 col-laborations）”• 早野 仁司, 高エネルギー加速器研究機構, ”超伝導加速空洞の最先端：表面の技術”• 佐藤 大輔, 産業総合研究所, ”IrCe カソード及びセラミックス加速管”• 吉岡正和, KEK 名誉教授、東北大学客員教授、岩手大学客員教授, ”国際リニアコライダー計画（ILC）の最近の状況と 100km リングヒッグスファクトリー（CEPC ＠中国）計画”

136• 岸田 昌浩, 九州大学大学院工学研究院, ”水素と金属によって生じる異常発熱現象の従来科学的検証”• 尾立 晋祥, 東京理科大学名誉教授, ”An attempt for the low-temperature nuclear synthesis”• Chayut Thanapirom, ”Terahertz Technology Laboratory, NECTEC, Thailand Research Status of
TTL – SSDRU – NECTEC”• ”配管等継ぎ手の取扱い安全講習会（学内限定）”• 門叶 冬樹, 山形大学理学部, ”炭素１４を用いた AMS 研究（兼 定期放射線教育の特別講演）”• 阪井 寛志, 高エネルギー加速器研究機構, ”窒素処理を用いた超伝導加速空洞の高加速勾配、高 Q 値に向けた研究開発”• 山口 貴之, 埼玉大学理工学研究科, ”重イオン蓄積リングを用いた RI ビーム物理実験の現状と将来”

ELPH Annual Report, Tohoku University (2018)137

Radiation Safety Report 2018
Radiation Safety Office

放射線安全管理室より、㻞㻜㻝㻤 年度（平成 㻟㻜 年 㻠 月～平成 㻟㻝 年 㻟 月）の報告を以下の通り行う。㻌

§1．㻌 許認可申請
㻴㻟㻜 年㻌 㻠 月㻌 㻝 日㻌 㻌 氏名等の変更㻌 （総長交代のため）
㻴㻟㻜 年㻌 ５月２１日㻌 㻌 放射線取扱主任者㻌 選任㻌 （南部健一、時安敦史）§2．㻌 個人管理㻞㻚㻝㻌 放射線業務従事者登録
㻝㻤㻡 人（㻌 東北大㻌 㻣㻝 人㻌 学外㻌 㻥㻣 人㻌 研究者以外㻌 㻝㻣 人）㻌

㻞㻚㻞㻌 個人被ばく管理㻌㻝 年間の個人被ばく線量㻌 㻌 㻡㻌㼙㻿㼢㻌 以下㻌 㻝㻤㻡 人㻌㻞㻚㻟㻌 教育訓練㻌
定期講習㻌
平成 㻟㻜 年 㻣 月 㻥 日㻌 登録前教育 㻝㻡 人㻌 再教育 㻤㻝 人㻌
特別講演の内容：㻌
山形大学理学部㻌 門叶冬樹㻌 氏㻌 㻌 「炭素 㻝㻠 を用いた 㻭㻹㻿 研究」㻌不定期の講習㻌
再教育㻌 㻝㻢 回㻌 㻠㻞 人㻌
登録前教育（新規教育）㻌 㻞㻞 回㻌 㻠㻢 人㻌§㻟．自主点検年 㻞 回実施㻌 㻌 平成 㻟㻜 年 㻥 月 㻞㻢 日、平成 㻟㻝 年 㻟 月 㻞㻡 日

§㻠．放射性同位元素製造記録
㻞㻜㻝㻤 年度に本加速器施設で製造され，共同研究に使用された放射性同位元素は次の通りである。

138

核種㻌

数量㻌 㻔㼗㻮㼝㻕㻌㻿㼞㻙㻤㻡㻌

㻢㻢㻜㻺㼍㻙㻞㻞㻌

㻤㻜㻝㻾㼎㻙㻤㻢㻌

㻢㻤㻜㻺㼍㻙㻞㻠㻌

㻡㻜㻜㼆㼞㻙㻤㻤㻌

㻞㻘㻡㻜㻜

㻷㻙㻠㻞

㻤㻘㻞㻜㻜

㻺㼎㻙㻥㻡㻌

㻠㻜㻜㻷㻙㻠㻟㻠㻜㻘㻠㻤㻝

㻹㼛㻙㻥㻥㻌

㻠㻠㻘㻜㻜㻜

㼀㼕㻙㻠㻠㻌

㻥㻿㼏㻙㻠㻢㻌

㼙㻭㼓㻙㻝㻜㻢㻌

㻝㻝㻞㻘㻜㻜㻜

㻮㼍㻙㻝㻟㻝㻌

㻞㻜㻯㼍㻙㻠㻣㻌

㻤㻜㻯㼟㻙㻝㻟㻞㻌

㻝㻘㻜㻜㻤㻿㼏㻙㻠㻣㻌

㻥㻘㻜㻜㻜㼙㻮㼍㻙㻝㻟㻡㻌

㻠㻘㻤㻜㻜

㼂㻙㻠㻤

㻢㻜㻜

㻯㼟㻙㻝㻟㻢㻌

㻝㻝㻘㻞㻤㻜

㻲㼑㻙㻡㻟㻌

㻟㻜㻜㻼㼙㻙㻝㻠㻟㻌

㻞㻜㻜㻺㼕㻙㻡㻢㻌

㻝㻘㻜㻜㻜㼀㼍㻙㻝㻤㻜㻌

㻝㻜㻘㻜㻜㻜

㻯㼛㻙㻡㻣㻌

㻞㻘㻞㻤㻟㼀㼘㻙㻞㻜㻞㻌

㻥㻘㻜㻜㻜㻺㼕㻙㻡㻣㻌

㻥㻘㻜㻡㻜㻴㼓㻙㻞㻜㻟㻌

㻝㻘㻠㻜㻜㻿㼑㻙㻣㻡㻌

㻢㻜㻜

全 㻞㻥 核種㻌

計 㻝㻣㻜㻘㻤㻡㻣㻚㻤㻌㼗㻮㼝㻌㻾㼎㻙㻤㻠㻌

㻠㻚㻤

IV. List of Publication

ELPH Annual Report, Tohoku University (2018)

139

List of Publication (論文リスト) (2018)

Papers Published in Refereed Journals
Bunch Length Measurement Employing Cherenkov Radiation from a Thin Silica Aerogel
K. Nanbu, Yuki Saito, Hirotoshi Saito, Shigeru Kashiwagi, Fujio Hinode, Toshiya Muto and
H. HamaParticles, 1(1), 305-314 (2018).
Observation of coherent undulator radiation in THz region
Shigeru Kashiwagi, Taro Abe, Hirotoshi Saito, Fujio Hinode, Ken Kanomata, Sadao Imura,Toshiya Muto, Ikuro Nagasawa, Ken-ichi Nanbu, Shingo Ninomiya, Nobuyuki Nishimori,
Yuki Saito, Ken Takahashi and H. Hama
Infrared Physics & Technology 93, 335-339, (2018).
Measurement of Proton Charge Radius by Low-Energy Electron Scattering
T. Suda, T. Aoyagi, Y. Honda, Y. Maeda, S. Miura, T. Muto, K. Namba, K. Nanbu,
K. Takahashi, T. Tamae and K. Tsukada
Journal of Particle Accelerator Society of Japan, 15 (2018) 52-59.
Extraction behavior of rutherfordium as a cationic fluoride complex with a TTA chelate extractant from
HF/HNO3 acidic solutions
A. Yokoyama, Y. Kitayama, Y. Fukuda, H. Kikunaga, M. Murakami Y. Komori, S. Yano,
H. Haba, K. Tsukada, A. Toyoshima
Radiochimica Acta 107 (2019) 27-32
Use of different surface covering materials to enhance removal of radiocaesium in plants and upper soil
from orchards in Fukushima prefecture
M. Sato, H. Akai, Y. Saito, T. Takase, H. Kikunaga, N. Sekiya, T. Ohtsuki, K. Yamaguchi
Journal of Environmental Radioactivity 196 (2019) 204-211
短寿命 RI 供給プラットフォーム実現のための放射線障害防止法上の手続きについて
鈴木智和，渡部浩司，菊永英寿，羽場宏光，福田光宏
日本放射線安全管理学会誌 17 (2018) 121-124
Distribution of LAT1-targeting PET tracer was independent of the tumor blood flow in rat xenograftmodels of C6 glioma and MIA PaCa-2
Masanao Aoki, Tadashi Watabe Shushi Nagamori, Sadahiro Naka, Hayato Ikeda,
Pornparn Kongpracha, Genki Horitsugi, Yasukazu Kanai, Eku Shimosegawa, Yoshikatsu Kanai,140

Jun Hatazawa
Annals of Nuclear Medicine, in press.
Ultracompact Compton camera for innovative gamma-ray imaging
J. Kataoka, A. Kishimoto, T. Taya, S. Mochizuki, L. Tagawa, A. Koide, K. Sueoka, H. Morita,
T. Maruhashi, K. Fujieda, T. Kurihara, M. Arimoto, H. Okochi, N. Katsumi, S. Kinno,
K. Matsunaga, H. Ikeda, E. Shimosegawa, J. Hatazawa, S. Ohsuka, T. Toshito, M. Kimura,
Y. Nagao, M. Yamaguchi, K. Kurita, N. Kawachi
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers,
Detectors and Associated Equipment 912, 1–5 (2018).
Application of astatine-210: evaluation of astatine distribution and effect of pre-injected iodide in wholebody of normal rats
Hayato Ikeda, Yoshihiko Hayashi, Naruto Takahashi, Tadashi Watabe, Yasukazu Kanai,
Atsushi Shinohara, Hiroki Kato, Hiroshi Watabe, Eku Shimosegawa, Jun Hatazawa
Applied Radiation and Isotopes 139, 251–255 (2018).
Observation of a Be double-Lambda hypernucleus in the J-PARC E07 experiment
H. Ekawa et al.
Prog. Theor. Exp. Phys. 2019 (2019) 021D02(1-11)
N-myristoylation and S-acylation are common modifications of Ca 2+ regulated Arabidopsis kinases andare required for activation of the SLAC1 anion channel
Saito, S., Hamamoto, S., Moriya, K., Matsuura, A., Sato, Y., Muto, J., Noguchi, H.,
Yamauchi, S., Tozawa, Y., Ueda, M., Hashimoto, K., Köster, P. Qiuyan. D., Held, K., Kudla, J.,
Utsumi, T. and Uozumi, N.
New Phytol. 218, 1504-1521 (2018)
In vitro and in vivo characterization of modulation of the vacuolar cation channel TRPY1 from
Saccharomyces cerevisiae
Hamamoto, S., Mori, Y., Yabe, I. and Uozumi，N.
FEBS J. 285, 1146–1161 (2018)
Reduction of spermidine content resulting from inactivation of two arginine decarboxylases increases
biofilm formation in Synechocystis sp. PCC 6803
Kera, K., Nagyama, T., Nanatani, K., Saeki-Yamoto, C., Tominaga, A., Souma, S., Miura, N.,
Takeda, K., Kayamori, S., Ando, E., Higashi, K., Igarashi, K. and Uozumi, N.
J. Bacteriol. 200 (9), E00664-17 (2018)
Ion channels regulate nyctinastic leaf opening in Samanea saman.
Oikawa, T., Ishimaru, Y., Munemasa, S., Takeuchi, Y., Washiyama, K. Hamamoto, S.,
Yoshikawa, N., Mutara, Y., Uozumi, N. and Ueda, M.
Current Biology 28, 2230–2238 (2018)

141

Measurement of mechanical properties of single Synechocystis sp. strain PCC6803 cells in different
osmotic concentrations using robot integrated microfluidic chip
Chang,D., Sakuma, S., Kera, K., Uozumi, N. and Arai F.
Lab Chip 18, 1241-1249 (2018)
Identification and characterization of compounds that affect stomatal movements
Toh, S., Inoue, S., Toda Y., Yuki, T., Suzuki, K., Hamamoto, S., Fukatsu, K., Aoki, S.,
Uchida, M., Asai, E., Uozumi, N., Ayato S. and Kinoshita, T.
Plant Cell Physiol. 59, 1568-1580 (2018)
Coupled-channels analyses for 9,11Li+208Pb fusion reactions with multi-neutron transfer couplings
K.-S. Choi, M.-K. Cheoun, W.Y. So, K. Hagino, and K.S. Kim,
Phys. Lett. B780 (2018) 455-460.
Origin of a maximum of astrophysical S factor in heavy-ion fusion reactions at deep subbarrier energies
K. Hagino, A.B. Balantekin, N.W. Lwin, and Ei Shwe Zin Thein,
Phys. Rev. C97 (2018) 034623.
Role of hexadecapole deformation of the projectiles in heavy-ion subbarrier fusion reactions of the 28Si
nucleusG. Kaur, K. Hagino, and N. Rowley,Phys. Rev. C97 (2018) 064606.
Disappearance of nuclear deformation in hypernuclei: a perspective from a beyond-mean-field study
H. Mei, K. Hagino, J.M. Yao, and T. Motoba,
Phys. Rev. C97 (2018) 064318.
Hot fusion reactions with deformed nuclei for synthesis of superheavy nuclei: an extension of thefusion-by-diffusion model
K. Hagino,
Phys. Rev. C98 (2018) 014607.
Branching ratios for deexcitation processes of daughter nuclei following invisible dinucleon decays in 16O
K. Hagino and M. Nirkko,
J. of Phys. G45 (2018) 105105.
A compensated multi-gap RPC with 2 m strips for the LEPS2 experimentK. Watanabe, S. Tanaka, W.C. Chang, H. Chen, M.L. Chu, J.J. Cuenca-Garcia, T. Gogami,
D. Gonzalez-Diaz, M. Niiyama, Y. Ohashi, H. Ohnishi, N. Tomida, M. Yosoi
Nuclear Instrument and Method, A925 (2019) 188-192—"K−pp ", a K-Meson Nuclear Bound State, Observed in 3He(K−,Λp)n Reactions
S. Ajimura, H. Asano, G. Beer, C. Berucci, H. Bhang, M. Bragadireanu, P. Buehler, L. Bussog,
M. Cargnelli, S. Choi, C. Curceanu, S. Enomoto, H. Fujioka, Y. Fujiwara, T. Fukuda,
C. Guaraldo, T. Hashimoto, R.S. Hayano, T. Hiraiwa, M. Iio, M. Iliescu, K. Inoue, Y. Ishiguro,142

T. Ishikawa, S. Ishimoto, K. Itahashi, M. Iwasaki, K. Kanno, K. Kato, Y. Kato, S. Kawasaki,
P. Kienle, H. Kou, Y. Ma, J. Marton, Y. Matsuda, Y. Mizoi, O. Morra, T. Nagae, H. Noumi,
H. Ohnishi, S. Okada, H. Outa, K. Piscicchia, Y. Sada, A. Sakaguchi, F. Sakuma, M. Sato,
A. Scordo, M. Sekimoto, H. Shi, K. Shirotori, D. Sirghii, F. Sirghii, K. Suzuki, S. Suzuki,
T. Suzuki, K. Tanida, H. Tatsuno, M. Tokuda, D. Tomono, A. Toyoda, K. Tsukada,
O. VazquezDocei, E. Widmann, T. Yamaga, T. Yamazaki, Q. Zhang, J. Zmeskal
Physics Letter B789 (2019) 620-625
Non-strange dibaryons studied in the d→π0π0d reaction
T. Ishikawa, H. Fujimura, H. Fukasawa, R. Hashimoto, Q. He, Y. Honda, T. Iwata, S. Kaida,
H. Kanda, J. Kasagi, A. Kawano, S. Kuwasaki, K. Maeda, S. Masumoto, M. Miyabe,
F. Miyahara, K. Mochizuki, N. Muramatsu, A. Nakamura, K. Nawa, S. Ogushi, Y. Okada,K. Okamura, Y. Onodera, K. Ozawa, Y. Sakamoto, M. Sato, H. Shimizu, H. Sugai, K. Suzuki,
Y. Tajima, Y. Taniguchi, Y. Tsuchikawa, H. Yamazaki, R. Yamazaki, H.Y. Yoshida.
Phys. Lett. B 789, 413 (2019).
Development of a transmittance monitor for high-intensity photon beams
Y. Matsumura, T. Ishikawa, Y. Honda, S. Kido, M. Miyabe, I. Nagasawa, K. Nanbu,
H. Shimizu, K. Takahashi, Y. Tsuchikawa, H. Yamazaki
Nucl. Instrum. and Meth. A 902, 103 (2018).
Profile measurement of circulating electrons in a synchrotron by inserting a carbon wire,
Y. Obara, T. Ishikawa, H. Hama, F. Hinode, H. Kanda, S. Kashiwagi, M. Miyabe, T. Muto,
K. Ozawa, H. Shimizu, A.O. Tokiyasu
Nuclear Instruments and Methods in Physics Research Section A 922, 108-113 (2019).
Possible η′d bound state and its s-channel formation in the γd→ηd reaction
T. Sekihara, H. Fujioka, T. Ishikawa
Physical Review C 97, 045202 (2018).
First measurement of coherent ϕ-meson photoproduction from 4He near threshold
T. Hiraiwa, M. Yosoi, M. Niiyama, Y. Morino, Y. Nakatsugawa, M. Sumihama, D. S. Ahn,
J. K. Ahn, W. C. Chang, J. Y. Chen, S. Daté, H. Fujimura, S. Fukui, K. Hicks, T. Hotta,
S. H. Hwang, T. Ishikawa, Y. Kato, H. Kawai, H. Kohri, Y. Kon, P. J. Lin, Y. Maeda,
M. Miyabe, K. Mizutani, N. Muramatsu, T. Nakano, Y. Nozawa, Y. Ohashi, T. Ohta, M. Oka,
C. Rangacharyulu, S. Y. Ryu, T. Saito, T. Sawada, H. Shimizu, E.A. Strokovsky, Y. Sugaya,
K. Suzuki, A. O. Tokiyasu, T. Tomioka, T. Tsunemi, M. Uchida, T. Yorita
Phys. Rev. C97 (2018) 035208.
Differential cross section and photon-beam asymmetry for the γp→π+n reaction at forward π+ angles at
Eγ=1.5–2.95 GeV

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H. Kohri, S.Y. Wang, S.H. Shiu, W.C. Chang, Y. Yanai, D.S. Ahn, J.K. Ahn, J.Y. Chen,
S. Daté, H. Ejiri, H. Fujimura, M. Fujiwara, S. Fukui, W. Gohn, K. Hicks, A. Hosaka, T. Hotta,
S.H. Hwang, K. Imai, T. Ishikawa, K. Joo, Y. Kato, S. H. Kim, Y. Kon, H.S. Lee, Y. Maeda,
T. Mibe, M. Miyabe, Y. Morino, N. Muramatsu, T. Nakano, Y. Nakatsugawa, M. Niiyama,
H. Noumi, Y. Ohashi, T. Ohta, M. Oka, J.D. Parker, C. Rangacharyulu, S.Y. Ryu, T. Sawada,
H. Shimizu, Y. Sugaya, M. Sumihama, T. Tsunemi, M. Uchida, M. Ungaro, and M. Yosoi(LEPS Collaboration)
Physical Review C 97, 015205 (2018).
Differential Cross Section and Photon-Beam Asymmetry for the γp→π−Δ++(1232) Reaction at Forward π−
Angles for Eγ=1.5–2.95 GeV
H. Kohri, S.H. Shiu, W.C. Chang, Y. Yanai, D.S. Ahn, J.K. Ahn, J.Y. Chen, S. Daté, H. Ejiri,
H. Fujimura, M. Fujiwara, S. Fukui, W. Gohn, K. Hicks, A. Hosaka, T. Hotta, S.H. Hwang,
K. Imai, T. Ishikawa, K. Joo, Y. Kato, Y. Kon, H.S. Lee, Y. Maeda, T. Mibe, M. Miyabe,
Y. Morino, N. Muramatsu, T. Nakano, Y. Nakatsugawa, S.i. Nam, M. Niiyama, H. Noumi,
Y. Ohashi, T. Ohta, M. Oka, J.D. Parker, C. Rangacharyulu, S.Y. Ryu, T. Sawada, H. Shimizu,
E.A. Strokovsky, Y. Sugaya, M. Sumihama, T. Tsunemi, M. Uchida, M. Ungaro, S. Y. Wang,
and M. Yosoi (LEPS Collaboration)
Physical Review Letters 120, 202004 (2018).
Photoproduction of Λ and Σ0 hyperons off protons with linearly polarized photons at E γ=1.5-3.0 GeV
S. H. Shiu, H. Kohri, W. C. Chang, D. S. Ahn, J. K. Ahn, J. Y. Chen, S. Daté, H. Ejiri, H.
Fujimura, M. Fujiwara, S. Fukui, W. Gohn, K. Hicks, T. Hotta, S. H. Hwang, K. Imai, T.
Ishikawa, K. Joo, Y. Kato, Y. Kon, H. S. Lee, Y. Maeda, T. Mibe, M. Miyabe, K. Mizutani, Y.
Morino, N. Muramatsu, T. Nakano, Y. Nakatsugawa, M. Niiyama, H. Noumi, Y. Ohashi, T.
Ohta, M. Oka, J. D. Parker, C. Rangacharyulu, S. Y. Ryu, T. Sawada, H. Shimizu, Y. Sugaya,
M. Sumihama, T. Tsunemi, M. Uchida, M. Ungaro, and M. Yosoi (LEPS Collaboration)
Phys. Rev. C 97(2018)015208
Direct measurements of the lifetime of medium-heavy hypernuclei
X. Qiu,L.Tang, C. Chen, A. Margaryan, S.A. Wood, P. Achenbach, A. Ahmidouch,
I. Albayrak, D. Androic, A. Asaturyan, R. Asaturyan, O. Ates, R. Badui, P. Baturin,
W. Boeglin, J. Bono, E. Brash, P. Carter, X. Chen, A. Chiba, M.E. Christy, M.M. Dalton,
S. Danagoulian, R. DeLeo, lD. Doi, M. Elaasar, R. Ent, H. Fenker, Y. Fujii, M. Furic, M.
Gabrielyan, L. Gan, F. Garibaldi, D. Gaskell, A. Gasparian, T. Gogami, O. Hashimoto, T. Horn,
B. Hu, EdV. Hungerford, M. Jones, H. Kanda, M. Kaneta, D. Kawama, H. Khanal, M. Kohl,
A. Liyanage, W. Luo, K. Maeda, P. Markowitz, G. Marikyan, T. Maruta, A. Matsumura,
V. Maxwell, A. Mkrtchyan, H. Mkrtchyan, S. Nagao, S.N. Nakamura, A. Narayan, C. Neville,
G. Niculescu, M.I. Niculescu, A. Nunez, Nuruzzaman, Y. Okayasu, T. Petkovic, J. Pochodzalla,

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J. Reinhold, V.M. Rodriguez, C. Samanta, B. Sawatzky, T. Seva, A. Shichijo, V. Tadevosyan,
N. Taniya, K. Tsukada, M. Veilleux, W. Vulcan, F.R. Wesselmann, T. Yamamoto, Z. Ye,
K. Yokota, L. Yuan, S. Zhamkochyan, L. Zhu
Nuclear Physics A 973 (2018) 116-148.
Revealing Color Forces with Transverse Polarized Electron Scattering
Armstrong, W. and Kang, H. and Liyanage, A. and Maxwell, J. and Mulholland, J. andNdukum, L. and Ahmidouch, A. and Albayrak, I. and Asaturyan, A. and Ates, O. and
Baghdasaryan, H. and Boeglin, W. and Bosted, P. and Brash, E. and Butuceanu, C. andBychkov, M. and Carter, P. and Chen, C. and Chen, J.-P. and Choi, S. and Christy, M. E. andCovrig, S. and Crabb, D. and Danagoulian, S. and Daniel, A. and Davidenko, A. M. andDavis, B. and Day, D. and Deconinck, W. and Deur, A. and Dunne, J. and Dutta, D. andEl Fassi, L. and Ellis, C. and Ent, R. and Flay, D. and Frlez, E. and Gaskell, D. and Geagla, O.
and German, J. and Gilman, R. and Gogami, T. and Gomez, J. and Goncharenko, Y. M. andHashimoto, O. and Higinbotham, D. and Horn, T. and Huber, G. M. and Jones, M. andJones, M. K. and Kalantarians, N. and Kang, H-K. and Kawama, D. and Keith, C. and
Keppel, C. and Khandaker, M. and Kim, Y. and King, P. M. and Kohl, M. and Kovacs, K. andKubarovsky, V. and Li, Y. and Liyanage, N. and Luo, W. and Mack, D. and Mamyan, V. andMarkowitz, P. and Maruta, T. and Meekins, D. and Melnik, Y. M. and Meziani, Z.-E. and
Mkrtchyan, A. and Mkrtchyan, H. and Mochalov, V. V. and Monaghan, P. and Narayan, A.
and Nakamura, S. N. and Nuruzzaman, A. and Pentchev, L. and Pocanic, D. and Posik, M. and
Puckett, A. and Qiu, X. and Reinhold, J. and Riordan, S. and Roche, J. and Rond¥'on, O. A.
and Sawatzky, B. and Shabestari, M. and Slifer, K. and Smith, G. and Soloviev, L. F. andSolvignon, P. and Tadevosyan, V. and Tang, L. and Vasiliev, A. N. and Veilleux, M. andWalton, T. and Wesselmann, F. and Wood, S. and Yao, H. and Ye, Z. and Zhang, J. and Zhu, L.
(SANE Collaboration),
Physical Review Letters 122 (2019) 022002-1-7.
Novel optical interferometry of synchrotron radiation for absolute electron beam energy measurements
P. Klag, P. Achenbach, M. Biroth, T. Gogami, P. Herrmann, M. Kaneta, Y. Konishi, W. Lauth,
S. Nagao, S.N. Nakamura, J. Pochodzalla, J. Roser, Y. Toyama
Nuclear Instruments and Methods in Physics A, 910 (2018) 147-156
Experimental techniques and performance of -hypernuclear spectroscopy with the (e, e’K+) reaction
T. Gogami, C. Chen, Y. Fujii, O. Hashimoto, M. Kaneta, D. Kawama, T. Maruta, A. Matsumura,
S. Nagao, S.N. Nakamura, Y. Okayasu, J. Reinhold, L. Tang, K. Tsukada, S.A. Wood, L. Yuan
Nuclear Instruments and Methods in Physics A, 900 (2018) 69-83
Neutral Kaon Spectrometer 2

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M. Kaneta, B. Beckford, T. Fujii, Y. Fujii, K. Futatsukawa, Y.C. Han, O. Hashimoto, K. Hirose,
T. Ishikawa, H. Kanda, C. Kimura, K. Maeda, S.N. Nakamura, K. Suzuki, K. Tsukada,F. Yamamoto, H. Yamazaki
Nuclear Instruments and Methods in Physics A, 886 (2018) 88-103—

Search for KL→0νν and KL→0X0 Decays at the J-PARC KOTO ExperimentJ. K. Ahn, B. Beckford, J. Beechert, K. Bryant, M. Campbell, S. H. Chen, J. Comfort, K. Dona,
N. Hara, H. Haraguchi, Y. B. Hsiung, M. Hutcheson, T. Inagaki, I. Kamiji, N. Kawasaki,
E. J. Kim, J. L. Kim, Y. J. Kim, J. W. Ko, T. K. Komatsubara, K. Kotera, A. S. Kurilin,
J. W. Lee, G. Y. Lim, C. Lin, Q. Lin, Y. Luo, J. Ma, Y. Maeda, T. Mari,T. Masuda,
T. Matsumura, D. Mcfarland, N. McNeal, J. Micallef, K. Miyazaki, R. Murayama, D. Naito,
K. Nakagiri, H. Nanjo, H. Nishimiya, T. Nomura, M. Ohsugi, H. Okuno, M. Sasaki, N. Sasao,
K. Sato, T. Sato, Y. Sato, H. Schamis, S. Seki, N. Shimizu, T. Shimogawa, T. Shinkawa,S. Shinohara, K. Shiomi, S. Su, Y. Sugiyama, S. Suzuki, Y. Tajima, M. Taylor, M. Tecchio,
M. Togawa, Y. C. Tung, Y. W. Wah, H. Watanabe, J. K. Woo, T. Yamanaka, and H. Y. Yoshida
Physical Review Letters 122(2) · January 2019
Excess heat evolution from nanocomposite samples under exposure to hydrogen isotope gases
A. Kitamura, A. Takahashi, K. Takahashi, R. Seto, T. Hatano, Y. Iwamura, T. Itoh, J. Kasagi,
M. Nakamura, M. Uchimura, H. Takahashi, S. Sumitomo, T. Hioki, T. Motohiro, Y. Furuyama,
M. Kishida, H. Matsune
International Journal of Hydrogen Energy 43 (2018) 16187-16200.
Direct measurement of astrophysical factor S(E) and screening potential for 9Be(p,)6Li reaction at low
energyKaihong Fang, Zhang Qian, Chen Bingjun, Zhang Zhengwei, Wang Qiang, Wang Tieshan,
Jirohta Kasagi, Hu Jun, Xu Shiwei
Phys. Lett. B785 (2018) 262-267.

Papers Published in International Conference Proceedings
A DESIGN STUDY OF THE ELECTRON-DRIVEN ILC POSITRON SOURCE INCLUDING BEAM
LOADING EFFECT
Hisayasu Nagoshi, Masao Kuriki, Tohru Takahashi, Kentaro Negishi, Tsunehiko Omori,
Masanori Satoh, Yuji Seimiya, Junji Urakawa, Yoske Sumitomo, Shigeru Kashiwagi,
Proceedings of the 9th Particle accelerator conference (IPAC2018),
Vancouver, BC, Canada, MOPMF077, pp311-314, 2018
AN OPTIMIZATION OF POSITRON INJECTOR OF ILC
M. Kuriki, Y. Seimiya, T. Okugi, M. Satoh, J. Urakawa, S. Kashiwagi,

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Proceedings of the 9th Particle accelerator conference (IPAC2018), Vancouver, BC, Canada,
MOPMF077, pp1334-1336, 2018
Study on Generation of Variable Polarized Coherent THz Radiation Using a Crossed Undulator,
H. Saito, H. Hama, F. Hinode, K. Kanomata, S. Kashiwagi, S. Miura, T. Muto, I. Nagasawa,
K. Nanbu, S. Ninomiya, K. Takahashi
Proc. 29th Linear Accelerator Conf. (LINAC'18), Beijing, China, Sep. 2018, pp. 157-159.
The SCRIT Electron Scattering Facility Project at the RIKEN RI Beam Factory
T. Ohnishi, A. Enokizono, M. Hara, M. Hori, S. Ichikawa, M. Wakasugi, M. Watanabe,
K. Adachi, T. Fujita, T. Hori, K. Kurita, M. Togasaki, N. Uchida, K. Yamada, T. Suda, T. Tamae,
K. Tsukada
Acta Phys. Polon. B49 (2018) 483
Beyond the neutron-drip line: two-neutron decay of unbound nuclei
K. Hagino and H. Sagawa
JPS Conf. Prof. 23 (2018) 012010 (8 pages).
Development of a new photon tagging system for GeV- beam line
M. Sasaki, T. Ishikawa, M. Iwasa, M. Miyabe, N. Muramatsu, H. Shimizu, Y. Tajima,
A.O. Tokiyasu, H. Yamazaki, H.Y. Yoshida2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC 2017) Conference Proceedings (2018) 8532685.

Invited Talk and Oral Presentations at International Conferences
Latest Status Accelerator Science Activities at Tohoku, Japan (Oral presentation)
Hiroyuki Hama
National Synchrotron Radiation Laboratory, University of Science and Technology, Hefei,
China, Dec. 26, 2018.
SLiT-J, a project of high brilliant compact 3 GeV light source in Japan (Invited oral presentation)
Hiroyuki Hama
Huazhong University of Science & Technology, Wuhan. China, Dec. 27, 2018
Latest Status Accelerator Science Activities at Tohoku, Japan (Oral presentation)
Hiroyuki Hama
National Synchrotron Radiation Research Center, Hsinchu, Taiwan, Nov. 8, 2018.
Accelerator-based Tunable Polarized THz Source (Oral presentation)
Hiroyuki Hama
Int. Conf. on Radiation and Emission in Materials (ICREM2018), Chiang Mai, Thailand, Nov.
22, 2018.
ELPH present status (Oral presentation)

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Hiroyuki Hama
Scandinova Systems, Uppsala, Sweden, Mar. 12, 2018.
Experiments of Short Bunch Production and Coherent Radiation at t‐ACTS (Oral presentation)
Fujio Hinode
NSRRCELPH Oneday Workshop on SHORT BUNCH PRODUCTION and COHERENT THz
RADIATION SOUCES, Hsinchu (Taiwan), Nov. 8‐9, 2018, (Oral)
Tsukuba International Congress Center, Tsukuba, Ibaraki, Japan,2018/Nov/13-17
Elastic electron scattering for proton charge radius determination
SUDA Toshimi
International workshop on the structure of the proton, 2019 年 2 月、山形、日本（招待講演）
Electron scattering for proton charge radius and charge density distribution of short-lived nuclei
SUDA Toshimi
International workshop on Proton and Neutron Densities and Radii in Nuclei and Related
Topics, 2018 年 12 月、北京、中国（招待講演）
Proton Charge Radius
SUDA Toshimi
Physics of Muonium and Related Topics, 2018 年 12 月、名古屋、日本（招待講演）
Elastic Electron Scattering for Proton Charge Radius Determination
SUDA Toshimi
Correlation in Partonic and Hadronic Interaction 2018, 2018 年 9 月、エレバン、アルメニア（招待講演）
Elastic electron scattering off proton using 60 MeV electron linac of Tohoku University
SUDA Toshimi
The Proton Radius Puzzle and Beyond, 2018 年 7 月、マインツ、ドイツ（招待講演）
Electron scattering
SUDA Toshimi
20th Northeastern Asian Symposium on Nuclear Physics in the 21th Century, 2018 年 9 月、名古屋、日本（招待講演）
Present status of the SCRIT electron scattering facility
TSUKADA Kyo
5th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Waikoloa, Hawaii, USA, October 23-27, 2018 (一般講演)
Present status of the SCRIT electron scattering facility
TSUKADA Kyo
5th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Waikoloa, Hawaii, USA, October 23-27, 2018 (一般講演)

148

Electron scattering from 208Pb and 132Xe ions at the SCRIT facility
TSUKADA Kyo
The 7th international conference on Trapped Charged Particles and Fundamental Physics(TCP2018) Traverse, Michigan, USA, September 30-October 5, 2018 (招待講演)
Present status of the electron scattering experiments at the SCRIT facility
TSUKADA Kyo
ECT* conference “Probing exotic structure of short-lived nuclei by electron scattering”,
Trento, Italy, July 16-20, 2018 (一般講演)
Elastic electron-proton scattering with low-energy electron beam at ELPH,
HONDA Yuki
5th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan,
Hilton Waikoloa Village Waikoloa, Hawaii, USA, October 23-27, 2018 (招待講演)
Status of ULQ2 experiment
HONDA Yuki
The 17th muon g-2/EDM collaboration meeting, KEK, Tsukuba, November 20-23, 2018
(口頭発表)
Summary of HYP2018
TAMURA Hirokazu
The 13st International Conference on Hypernuclear and Strange Particle Physics (HYP2018),
Portsmouth, VA, USA,

June 24-29, 2018（招待講演）

Recent results in Hypernuclear physics
TAMURA Hirokazu
International School of Nuclear Physics 40th Course “The Strong Interaction: From Quarks
and Gluons to Nuclei and Stars”, Erice, Italy, September 16-24, 2018 （招待講演）
Gamma-ray spectroscopy of hypernuclei
TAMURA Hirokazu
International Conference on Physics, Mandalay 2018 (ICPM21018) Mandalay, Myanmar,
November 25-27, 2018 （招待講演）
Strangeness Nuclear Physics
TAMURA Hirokazu
The 8th International Conference on Quarks and Nuclear Physics Tsukuba, Japan,
November 13-17, 2018（招待講演）
Optimum Control of Cellular Homeostasis in Photosynthetic Organism, Cyanobactria and Plant Cells
UOZUMI Nobuyuki
プラズマフォーラム 平成 31 年 1 月 21-22 日 仙台市
Heavy-ion fusion reactions for superheavy elements （Invited oral)

149

K. Hagino
Workshop on New Frontiers in Nuclear Physics and Nuclear Astrophysics,
Akdeniz University, Antalya, Turkey, May 28- June 1, 2018.
Fusion barrier distribution and superheavy elements （Invited oral)
K. Hagino
XLI Brazilian Meeting on Nuclear Physics, Maresias, Brazil, Sep. 2-6, 2018.
Mechanism of fusion reactions for superheavy nuclei （Invited oral)
K. Hagino
Workshop on Physics and chemistry of the heaviest elements and nuclei, Fifth Joint Meeting of
the Nuclear Physics Division of the APS and the JPS, Hawaii, Octber 23, 2018
Future experiments at J-PARC (Invited oral presentation)
Hiroaki Ohnishi
Future opportunities toward studies in low-energy hadron physics with strangeness,
Stefan Meyer Institute for Subatomic Physics, Vienna, AUSTRIA, December 3-5, 2018
Charmed meson in Nuclei at J-PARC (Invited oral presentation)
Hiroaki Ohnishi
Hadron structure and interaction in dense matter,
KEK Tokai campus, Tokai, Japan, November 11-12, 2018
Hadron physics at J-PARC (Invited oral presentation)
Hiroaki Ohnishi
SMI-Seminar, Stefan Meyer Institute for Subatomic Physics, Vienna, AUSTRIA,
December 5, 2018
Light meson photoproduction at SPring-8 LEPS2/BGOegg experiments (Invited oral presentation)
N. Muramatsu for the BGOegg collaboration
PWA10/ATHOS5 2018 (The International Workshop on Partial Wave and Advanced Tools for
Hadron Spectroscopy), IHEP, Beijing, July 16–20, 2018.
Photoproduction of light mesons at SPring-8 LEPS2/BGOegg experiments (Oral presentation)
N. Muramatsu, T. Hashimoto, T. Nam for the BGOegg collaboration
Fifth Joint Meeting of the Nuclear Physics Divisions of the APS and the JPS, Hawaii, Oct. 23–
27, 2018.
Baryon resonance studies at SPring-8 LEPS2/BGOegg experiments (Invited oral presentation)
N. Muramatsu, T. Hashimoto, T. Nam for the BGOegg collaboration
The 52nd Reimei Workshop “Experimental and Theoretical Hadron Physics: Recent Exciting
Developments”, J-PARC, Tokai, Jan. 9–11, 2019.
ω photoproduction on the proton near the threshold, (Invited oral plresentation)
Takatsugu Ishikawa

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The 52nd Reimei Workshop "Experimental and Theoretical Hadron Physics: Recent Exciting
Developments",
Ibaraki Quantum Beam Research Center (IQBRC), Tokai, Japan
January 09--11, 2019Non-strange dibaryon resonances observed in coherent double neutral-pion photoproduction on the
deuteron (Invited oral presentation, Keynote speech)
Takatsugu Ishikawa
8th International Conference on Quarks and Nuclear Physics,
Tsukuba, Japan, November 13-17, 2018.
Study of non-strange dibaryon resonances via coherent double neutral-meson photoproduction from thedeuteron (Oral presentation)
Takatsugu Ishikawa
XXII International Conference on Few-Body Problems in Physics,
Caen, France, July 9-13, 2018
AXION Experiment in Japan (Invited oral presentation)
A. O. Tokiyasu
Revealing the history of the universe with underground particle and nuclear research 2019,
Sendai, Japan, Mar.7 – Mar. 9, 2019
Spectroscopy of elctro-produced hypernuclei at JLab (Invited Oral presentation)
Satoshi Nakamura
13th International Conference on Hypernuclear and Strange Particle Physics (HYP2018),
Portsmouth, USA 24-29 June 2018.
Topics on (e,e'K+) spectroscopy of Λ hypernuclei at JLab (Plenary, Invited oral presentation)
Satoshi Nakamura
5th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan(Hawaii2018), Hawaii Island, USA, 23-27 Oct. 2018
Status of Λn Interaction study via the final state interaction in 𝛾𝛾+d→K++Λ+n production (Oralpresentation)

Masashi Kaneta
Fifth Join Meeting of the Nuclear Physics Divisions of the APS and the JPS
Hilton Wailoloa vilage, Hawaii, USA
2018/Oct/23-28
Status of Λn Interaction study via the final state interaction in 𝛾𝛾d→K+Λn production (Oral presentation)
Masashi Kaneta

8th International COnference on Quark and Nuclear Physics (QNP2018)
Tsukuba International Congress Center, Tsukuba, Ibaraki, Japan151

2018/Nov/13-17
Electromagnetic Calorimeter BGOegg for Quark Nuclear Physics (Invited oral)
H. Shimizu
The 33th Workshop on Radiation detectors and their uses, KEK, Jan. 28-30, 2019.
Anomalous Heat Effects Induced by Metal Nanocomposites and Hydrogen Gas (Oral presentation)
Y. Iwamura,The 21st International Conference for Condensed Matter Nuclear Science, Colorado State
University, Fort Collins, CO, USA, June 3 - 8, 2018.
Recent Advances in Heat Generation Experiments using Nano-sized Metal Composite and Hydrogen Gas
at Condensed Matter Nuclear Reaction Division of Tohoku University (Invited oral)
Yasuhiro Iwamura,2019 LANR/CF Colloquium at MIT, Massachusetts Institute of Technology, Cambridge, MA,
USA, March 23-24, 2019.
Search for -ray radiation in NiCuZr nano-metals and H2 gas system generating large excess heat（Oralpresentation）
Jirohta Kasagi,
The 21st International Conference on Condensed Matter Nuclear Science ICCF21, Fort Collins,
Colorado, USA, June 3-8, 2018.
STUDY ON GENERATION OF VARIABLE POLARIZED COHERENT THz RADIATION USING A
CROSSED UNDULATOR （Poster presentation）
Hirotoshi Saito
The 29th Linear Accelerator Conference, LINAC 18, (Beijin, China), 16-21 September 2018.
Beam Diagnostics Employing Cherenkov Light from Hollow Silica Aerogel Radiator of Low Refractive
Index（Oral presentation）
Shingo Ninomiya
NSRRC-ELPH One-day Workshop on SHORT BUNCH PRODUCTION and COHERENT
THz RADIATION SOUCES, (Taiwan), 8-9 November 2018,.
Crossed-undulator for Variable Polarized THz Source （Oral presentation）
Hirotoshi Saito
NSRRC-ELPH One-day Workshop on SHORT BUNCH PRODUCTION and COHERENT
THz RADIATION SOUCES, (Taiwan), 8-9 November 2018.
A high-resolution spectrometer for low-energy electron scattering for proton charge radius （Oralpresentation）
T. Aoyagi他
5th Joint Meeting of the APS Division of Nuclear Physics and the Physics Society of Japan,
ハワイ、米国, 2018年10月.

152

Development of an Aerogel Cherenkov counter for the LEPS2 experiment at SPring-8 （Oral presentation）
吉田千尋、
Fifth Joint Meeting of the Nuclear Physics Divisions of the APS and the JPS, Hawai, USA,
October 25, 2018.
Development of the Aerogel Cherenkov counter for the LEPS2/SPring-8 experiment to search for the
K−pp bound state （Poster presentation）
吉田千尋
International School for Strangeness Nuclear Physics (SNP School 2018),
RCNP, Osaka University, Osaka, August 1-3, 2018.

学位論文（電子光理学研究センター所属）
修士論文「陽子半径測定用の低エネルギー電子スペクトロメータ」
  青柳泰平平成  年度東北大学
修士論文「陽子半径測定用スペクトロメータの焦点面検出器」
  南波和希平成  年度東北大学
修士論文「/(36 実験のためのシリカエアロゲルチェレンコフ検出器の開発」
  吉田千尋平成  年度東北大学
修士論文「光反応による核内 η’中間子に関する研究」
  上田惟行平成  年度東北大学
修士論文「チェレンコフ光リングを用いた非破壊型ビームモニターの研究」
  二宮慎吾平成  年度東北大学

学位論文（他機関所属）
修士論文「+ HH’. ;実験における .中間子識別手法とその評価」
  板橋浩介平成  年度東北大学
修士論文「ハイパー核寿命測定実験用の新型粒子飛行時間測定器の開発」
  小西由浩平成  年度東北大学
修士論文「5HVHDUFKDQGGHYHORSPHQWRIDQHZILQHJUDLQHGVFLQWLOODWRUWUDFNHUIRUWKHXSJUDGHRI7.QHDUGHWHFWRU」
  藤田亮平成  年度東京大学

V. Members of Committees

153

Steering Committee
2018

Hiroyuki HAMA*

ELPH

Toshimi SUDA

ELPH

Hiroaki OHNISHI

ELPHFujio HINODE

ELPH

Shigeru KASHIWAGI

ELPHNorihito MURAMATSU

ELPH

Hidetoshi KIKUNAGA

ELPH

Hirokazu TAMURA

Graduate School of Science

Satoshi NAKAMURA

Graduate School of Science

Kouichi HAGINO

Graduate School of Science

Fuminori MISAIZU

Graduate School of Science

Yasushi KINO

Graduate School of Science

Nobuyuki UOZUMIGraduate School of Engineering

Shigeo MATSUYAMA

Graduate School of Engineering

Masaki FUJITA

Institute for Materials Research

Yuji TAKAKUWA

Institute of Multidisciplinary Research for Advanced Materials

Takeo EJIMA

Institute of Multidisciplinary Research for Advanced Materials

Keiichi EDAMATSU

Research Institute of Electrical Communication

Masatoshi ITOH

Cyclotron and Radioisotope Center

Kenji TSUDA

Frontier Research Institute for Interdisciplinary Sciences* Chairperson

154

General Advisory Committee
2018

Hiroyuki HAMA*

ELPH, Tohoku University

Toshimi SUDA

ELPH, Tohoku University

Hiroaki OHNISHI

ELPH, Tohoku University

Hidetoshi KIKUNAGA

ELPH, Tohoku University

Hirokazu TAMURA

Graduate School of Science, Tohoku University

Yasushi KINO

Graduate School of Science, Tohoku University

Masatoshi ITOHCYRIC, Tohoku University

Kenji TSUDA

Frontier Research Institute for Interdisciplinary Sciences, Tohoku
University

Tomohiro UESAKARIKEN Nishina Center

Daisuke JIDO

School of Science, Tokyo Institute of Technology

Takashi NAKANORCNP, Osaka University

Tomohumi NAGAE

Graduate School of Science, Kyoto University

Ryukou KATO

Accelerator Laboratory, KEK

Hideaki OHGAKI

IAE, Kyoto University

Akihiko YOKOYAMA

College of Science and Engineering, Kanazawa University

Yasuji OURA

Graduate School of Science and Engineering, Tokyo Metropolitan
University* Chairperson

155

Program Advisory Committee
2018

Toshimi SUDA

ELPH, Tohoku University

Hiroaki OHNISHI

ELPH, Tohoku University

Shigeru KASHIWAGI

ELPH, Tohoku University

Hidetoshi KIKUNAGA

ELPH, Tohoku University

Satoshi NAKAMURA*

Graduate School of Science, Tohoku University

Kazumasa SUGIYAMA

Institute for Materials Research, Tohoku University

Kiyoshi TANIDA

ASRC, Japan Atomic Energy Agency

Megumi NARUKI

Graduate School of Science, Kyoto University

Masaru YOSOIRCNP, Osaka University

Yoshihiko SHOJILASTI, University of Hyogo

Yasuji OURA

Graduate School of Science and Engineering, Tokyo Metropolitan
University

Koichi TAKAMIYA

Research Reactor Institute, Kyoto University* Chairperson

VI. Approved Experiments

157

平成 㻟㻜 度前期採択課題一覧㻌

課題番号
2892

課

題

名

7. 実験高度化のための細分型プラスチックシンチレータ検出器の性能評価

申込責任者
松原綱之

2893

6&5,7 実験用ドリフトチェンバーの性能評価

塚田暁

2894

)25(67超前方荷電粒子検出で拓く物理

石川貴嗣

2895

0HDVXUHPHQWRIΛ+OLIHWLPHZLWKSKRWRQEHDP

永尾翔

2896

単一コンパレータ法を用いた光量子放射化分析

大浦泰嗣

2897
2898

電子ライナックを用いた長寿命短寿命有用放射性トレーサー製造法の開発
家庭ごみ焼却スラグに含まれる希少金属元素の回収を目指した光量子放射化法による成分同定およびトレーサー作成 

菊永英寿

秋山和彦

158

平成 㻟㻜 度後期採択課題一覧㻌

課題番号
2899
2900
2905
2909
2910
2911
2903
2904
2906
2907
2908
2912
（随時）
2913
（随時）
2914
（随時）
2919
（随時）

課

題

名

 年生学生実験：電子ビームによる 0XOWL*DS 5HVLVWLYH
SODWH&KDPEHU の基礎研究
3HUIRUPDQFHHYDOXDWLRQRIWKHQH[WJHQHUDWLRQ'$4V\VWHPZLWKKLJKUDWHGHWHFWRUVIRUWKH-3$5&(H[SHULPHQW-3$5& ( 実験のための電子同定システムと 053& 検出器の性能評価
0XOWLJDS5HVLVWLYH3ODWH&KDPEHUの時間分解能性能評価
国際共同大学院「宇宙創成物理学」高度実験
吸収層からの光読み出しを利用し高いエネルギー精度を実現
するサンプリング型カロリメータの性能検証
7. 実験前置検出器アップグレード計画における細分型プラ
スチックシンチレータ検出器の性能評価
無担体 +J トレーサ製造のための 7O SQ +J 反応の励起関数測定電子ライナックを用いたアルカリ金属のキャリアフリー5, ト
レーサー製造法の開発
家庭ごみ焼却スラグに含まれる希少金属元素の回収を目指した光量子放射化法による成分同定およびトレーサー作成３
光量子放射化法によるプロメチウム（3P）内包金属フラーレンの合成を目的とした 5, 製造,9

申込責任者
大西宏明

0D<XH小沢恭一郎

金田 雅司

竹下徹

岩本康之介

後藤真一

池田隼人

秋山 和彦

秋山和彦

冷却 &&' を用いた非密封 5, 用イメージング装置の開発

菊永英寿-3$5&( 実験のための 053& 検出器の性能評価

小沢恭一郎小型のエアロジェルチェレンコフ検出器の光量評価

金田雅司

0R Q 0R 反応の収率向上のための : コンバータの最適厚さの検討
ミューオン J－('0 実験と陽子半径測定実験に向けた読み出し回路一体型シリコンストリップ検出器の性能評価試験

上坂充

本多佑記

ELPH ANNUAL REPORT 2018
December 2019
Research Center for Electron Photon Science, Tohoku University
1-2-1, Mikamine, Taihaku, Sendai 982-0826, Japan

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