ISSN 2186-7968

ELPH ANNUAL REPORT 2015

ELPH

ANNUAL REPORTTOHOKU UNIVERSITYTOHOKU UNIVERSITY

2015

EditorHINODE, Fujio
MURAMATSU, Norihito
MUTO, Toshiya
TSUKADA, Kyo

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/

ELPH ANNUAL REPORT 2015
December 2016

982-0826

仙台市太白区三神峯1-2-1

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

東北大学電子光理学研究センター
電話022-743-3400

Fax

022-743-3402

印刷所 株式会社 東北プリント
仙台市青葉区立町24番24号
TEL 022（263）1166㈹Preface
The ELPH Annual Report 2015 covers scientific and technical activities carried out at ResearchCenter for Electron Photon Science (ELPH), Tohoku University in FY2015 (April, 2015 to March, 2016).
ELPH has been a part of Joint Usage / Research Centers since FY2011. Joint Usage / Research Centers (JURC) system was engaged by the Ministry of Education, Culture, Sports, Science and Technology(MEXT) in FY2010 to encourage and promote collaborative research passing through the border of respective universities. Approximately 75 laboratories and research centers in national universities designated by the Minister of MEXT started their own activities under the program of JURC until FY2015
in which the term corresponds to the secondary stage of the six-year

Medium-term Goal and Plans

for national universities.
Because of the disaster of big Earthquake and Tsunami on March 11, 2011, an interim appraisal
regarding JURC activity in 2012 for the ELPH was clearly poor, and it was not acceptable for us. However accelerator operation was back in the end of FY2013, and completed amount of Joint Usage ofaccelerators in ELPH was fully recovered in FY2014. Although we had embarrassed particularly by
the steep rise of electricity price, we have performed exhaustive control of power consumption for every device equipped in accelerators and the facility utilities. In FY2015, the total machine operation
time reached over 2000 hours and the total users participated to beam experiments was more than 1000
people. Consequently the JURC end-term evaluation for ELPH was, correctly, A. It means we should
let us be substantial frame and pursuing interdisciplinary science for the next generation of Laboratory. We sincerely ask facility users and related scientific field communities for continuous supports andcooperation.
Director
Hiroyuki Hama

ELPH annual report, 2015
Contents
I. Papers

Development of a fast profile monitor with scintillating fiber hodoscopes for high-intensity
photon beams
T. Ishikawa, Y. Honda, H. Kanda, S. Kido, Y. Matsumura, M. Miyabe, H. Shimizu,
A. O. Tokiyasu, Y. Tsuchikawa, H. Yamazaki
Upgrade plan of the FOREST experiments at ELPH
T. Ishikawa, H. Fujioka, Y. Honda, Y. Inoue, K. Itahashi, H. Kanda, H. Kawai,
Y. Matsumura, K. Maeda, M. Miyabe, N. Muramatsu, H. Ohnishi, K. Ozawa,
M. Sasagawa, H. Shimizu, K. Shiraishi, M. Tabata, A.O. Tokiyasu, Y. Tsuchikawa

1

7

A beam test of a charge-to-time converting leading-edge discriminator for plastic-scintillator
signals13
T. Ishikawa, Y. Honda, Y. Inoue, H. Kanda, S. Kido, Y. Matsumura, M. Miyabe,
H. Shimizu, K. Shiraishi, A.O. Tokiyasu, Y. Tsuchikawa, H. Yamazaki
Development of a compact photon-beam profile monitor
S. Kido, T. Ishikawa, Y. Honda, H. Kanda, Y. Matsumura, M. Miyabe, I. Nagasawa,
H. Shimizu, Y. Tsuchikawa

31

Development of the photon tagger for the NKS2 experiment
H. Kanda, K. Honda, T. Ishikawa, M. Kaneta, K. Maeda, M. Miyabe, Y. Muroi,
S. Nagao, S. N. Nakamura, A. Ninomiya, T. Nishizawa, K. Ozeki, T. Sasaki,
A. O. Tokiyasu, Y. Toyama

37

新光子標識化装置 STB TaggerIIs で使用する MWDC の性能評価
Performance test of MWDC for a photon tagging system STB TaggerIIs
45
M. Sasaki, Y. Honda, Y. Inoue, T. Ishikawa, M. Iwasa, H. Kanauchi, S. Kido,
Y. Matsumura, D. Miura, M. Miyabe, N. Muramatsu, T. Sakurai, M. Sasagawa,M. Sei, Y. Seki, H. Shimizu, Y. Tajima, T. Takahashi, A.O. Tokiyasu, Y. Tsuchikawa,
H.Y. Yoshida
Measurement of the electron beam size at the BM5 radiator in the BST ring
Y. Obara, H. Hama, F. Hinode, T. Ishikawa, H. Kanda, S. Kashiwagi, M. Miyabe,
T. Muto, K. Ozawa, H. Shimizu, A.O. Tokiyasu
Performance of undoped CsI crystal with both-end readout for the KOTO experiment at
J-PARC
H. Nanjo, H. Haraguchi, M. Iwasa, H. Kanauchi, S. Su, T. Sakurai, M. Sasaki,
Y. Sugiyama, Y. Tajima, M. Togawa, T. Yamanaka, H.Y. Yoshida
Test of an X-ray flat panel sensor as a beam profile monitor
H. Kanda, K. Honda, T. Ishikawa, M. Kaneta, K. Maeda, M. Miyabe, Y. Muroi,
W. Nakai, S. N. Nakamura, A. Ninomiya, Y. Obara, K. Ozawa, K. Ozeki, T. Sasaki,

52

58

66

H. Shimizu, A.O. Tokiyasu
Performance test of a sampling calorimeter for the SPring-8/LEPS2 experiment
A. O. Tokiyasu, M. Yosoi, H. Goto, Y. Yanai, M. Miyabe

73

Longitudinal uniformity of the manufactured BGO crystals for the BGOegg calorimeter81
R. Yamazaki, T. Ishikawa, D.N. Grigoriev, R. Hashimoto, Q. He, Y. Honda,
G.N. Kuznetsov, S. Masumoto, M. Miyabe, N. Muramatsu, M. Nakamura, Y. Taniguchi,
Y. Tsuchikawa, H. Shimizu, Y.V. Vasiliev, H. Yamazaki
The status of SPring-8 LEPS2/BGOegg experiments
91
N. Muramatsu, J. K. Ahn, W-C Chang, J-Y Chen, S. Daté, T. Gogami, H. Goto,
H. Hamano, T. Hashimoto, Q. H. He, K. Hicks, T. Hiraiwa, Y. Honda, T. Hotta,
H. Ikuno, Y. Inoue, T. Ishikawa, I. Jaegle, Y. Kasamatsu, H. Katsuragawa, S. Kido,
H. Kohri, Y. Kon, S. Masumoto, Y. Matsumura, K. Miki, M. Miyabe, K. Mizutani,
T. Nakamura, T. Nakano, M. Niiyama, Y. Nozawa, Y. Ohashi, H. Ohkuma, H. Ohnishi,
T. Ohta, M. Oka, K. Ozawa, M. Sasagawa, T. Shibukawa, H. Shimizu, K. Shiraishi,
Y. Sugaya, M. Sumihama, S. Suzuki, S. Tanaka, A. O. Tokiyasu, N. Tomida, N. Tran,
Y. Tsuchikawa, H. Yamazaki, R. Yamazaki, Y. Yanai, T. Yorita, M. Yosoi
Commissioning of the SCRIT electron scattering facility with 132Xe target
99
K. Tsukada, K. Adachi, A. Enokizono, T. Fujita, M. Hara, M. Hori, T. Hori, S. Ichikawa,
K. Kurita, T. Ohnishi, T. Suda, T. Tamae, M. Togasaki, T. Tsuru, K. Yamada,
M. Wakasugi, M. Watanabe
Production of K-42,43 radioactive tracer
H. Kikunaga, K. Tsukada, T. Suda
土壌試料中の放射性ストロンチウムの迅速化学分離法の検討
Rapid chemical separation method of radioactive strontium in soil samples
I. Endo, Y. Oura

105

108

Study on metallofullerene encapsulating artificial radio element of promethium
K. Akiyama, S. Miyauchi

112

Study of W converter’s thickness of 100Mo(γ,n)99Mo process
J. Li, M. Lin, L. Sheng, Y. Guo, T. Oka, H. Kikunaga

116

II. Status Report

Status of accelerator Facilities in FY2015
Accelerator group

121

User Support Office Report in FY2015
M. Miyabe128

放射線安全管理室報告
Radiation Safety Report 2015
Radiation Safety Office131III. List of Publication

133

IV. Members of Committees

147

V. Approved Experiments

151

I. Papers

ELPH Annual Report, Tohoku University (2015)

1(ELPH Experiment : #2761)

Development of a fast profile monitor with scintillatingfiber hodoscopes for high-intensity photon beams
T. Ishikawa1 , Y. Honda1 , H. Kanda2 , S. Kido1 , Y. Matsumura1 , M. Miyabe1 ,H. Shimizu1 , A.O. Tokiyasu1 , Y. Tsuchikawa1 , and H. Yamazaki1
1Research Center for Electron Photon Science (ELPH), Tohoku University, Sendai 982-0826,
Japan
2

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

A fast beam-profile monitor has been developed for high-energy photon beamlines at the ResearchCenter for Electron Photon Science, Tohoku University. The monitor consists of a trigger system for thephoton identification and a tracker system for the position measurement. The position of the photon
converted into an electron-positron pair in a 0.5 mm-thick aluminum plate is measured. The pairproduction events are identified with a trigger plastic scintillator placed behind the plate. Charged
particles produced upstream are rejected with a charge veto plastic scintillator placed in front of theplate. The position of the electron-positron pair is determined by two hodoscopes made of scintillatingfibers with a cross section of 3×3 mm2 . The reconstruction of the incident position is made by a developed
logic module with a field-programmable gate array, multi-purpose logic module MPLM4X. The dead time
for processing an event is 35 ns, and a high data acquisition efficiency (∼ 100%) can be achieved withthis monitor for high-intensity photon beams in the normal operation corresponding to 20 MHz tagging
signals.

§ 1. Introduction

Two high-energy tagged photon beamlines [1, 2] were constructed for meson photoproduction ex-

periments [3] at the Research Center for Electron Photon Science (ELPH), Tohoku University. In bothbeamlines, bremsstrahlung photons are generated by inserting a thin carbon fiber into circulating electrons in the electron synchrotron [4]. The energy of the photon is determined by measuring the momentum of its corresponding post-bremsstrahlung electron [1, 2]. We have developed several versions ofprofile monitors giving a two dimensional intensity map of the photon beam for optimizing the photon
beam direction.
Two types of the measurement of the photon beam profile have been made at ELPH. One is ananalog-type measurement using a film or a charge-coupled device (CCD) video camera. A photon beam
spot is taken with an instant film or a fluorescent screen together with a video camera. They are placed
behind a thick metal plate, which is used as a radiator to produce secondary particles namely electronpositron pairs and associated X-rays. Although the analog-type measurements are simple, the linearityof the intensity map measured with a film or a video camera is not guaranteed due to reciprocity law

2failure characteristics or saturation effects. Therefore, alternative profile monitors with scintillatingfiber (SciFi) hodoscopes have been developed [5–7].

§ 2. Profile monitors with scintillating fiber hodoscopes

All the monitors consist of a trigger system for the photon identification and a tracker system forthe position measurement. The tracker system consists of two layers of SciFi hodoscopes. Each SciFi
measures a cross section of 3 × 3 mm2 . The trigger system consists of a plastic scintillator (PS) for

charge veto, an aluminum plate converter, one or two trigger PSs. Each of the charge and trigger PSs isconnected to a photomultiplier tube, Hamamatsu Photonics H7195, for which power supply boosters areused to work for high-intensity photon beams. The trigger condition of the data acquisition is describedas[charge PS] ⊗ [trigger PS](1)[charge PS] ⊗ [trigger PS1] ⊗ [trigger PS2].

(2)

or

The charge PS signal rejects the charged particles produced upstream. The discriminator thresholds for
producing logic signals of the charge and trigger PSs are set to 0.5Vmip and 1.5Vmip , respectively, where
Vmip is the average pulse height of the minimum ionizing particles.
The thicknesses of PSs has been reduced from 5 to 1 mm and a trigger PS has been removed in
the third generation monitor to be used for high-intensity photon beams. The charge PS with a size of
70 × 70 mm2 was connected to a H7195 PMT. The trigger PS with a size of 55 × 55 mm2 was connected to

two H7195 PMTs arranged in an L-formation [6]. The uniform energy response of the charge and trigger
PSs with respect to the incident position is important for minimizing the systematic uncertainty of themeasured profile.
The uniformity maps were measured for the charge and trigger PSs at by using 460 MeV/c positron
beam at ELPH [8]. Here, the aluminum plate for an e+ e− converter was removed. The trigger conditionof the uniformity map measurement was[x SciFi OR] ⊗ [y SciFi OR],(3)

where x (y) SciFi OR denotes the logic OR of sixteen x (y) SciFi signals. The energy distributions of
the charge and trigger PSs were obtained for 16 incident positions given by the responding x and y
SciFis. The peak position corresponding to the minimum ionizing particles for each incident position
was obtained by fitting the Moyal function [9] to the data. Fig. 1 shows the uniformity maps for the
charge Gv and trigger Gt1 and Gt2 PS signals. Here, the signal for the central incident position was
normalized to 1. The energy response was not uniform. An enhancement of the signal was observedat the PS side connected to a PMT, suggesting the size of the trigger PS was small. A signal drop wasobserved on the adjacent side connected to the other PMT, indicating that the L-type PMT connection
was not appropriate. Therefore, we have replaced the trigger PS with a trigger PS with an area of3
70 × 70 mm2 , and the scintillation light is collected only from one side. The details of the uniform map
measurement is described elsewhere [10].

20charge PS

trigger PS 1

trigger PS 2

54

y (mm)

10

3

0

2

-10

1

-20
-20

-10

0

10

20 -20x (mm)-100

10

20 -20-10x (mm)

0

10

20

0

x (mm)

Fig.1. Uniformity maps for the charge and trigger PS signals. The trigger PS is connected to
two H7195 PMTs arranged in an L-formation. The trigger PS 1 (2) signal is given by a
PMT connected to the +x (+y) side. The peak position of the pulse height distribution
for minimum ionizing particles is obtained for each impact point and normalized to thesignal in the central position. The gray scale is common to all the panels.

§ 3. Measured photon-beam profiles

A method for creating an intensity map of the photon beam in the fourth generation of the profile

monitor is similar to the third generation. The newly developed NIM module, multi-purpose logic module
MPLM4X [11] with a field-programmable gate array, Xilinx Spartan-6 [12], is used for the data acquisition of the profile monitor. The Data AcQuisition (DAQ) with MPLM4X for the profile monitor is programmed in VHDL using an integrated development environment Xilinx ISE WebPACK Ver. 14.7 [13].
The time jitter of the logic is made less than 5 ns by using edge-aligned signals with the 200 MHz clock.
The functions of the profile monitor are as follows:
1. the incident position is determined with respect to the trigger signal,
2. the number of counts for all the positions are stored,
3. the counting process can be gated,
4. the incident position can be determined in coincidence with the photon-tagging signal, and
5. The data acquisition can be controlled with an RS-232C communication.
Since the MPLM4X logic module can accept and produce the NIM logic signals, additional level converters are prepared between NIM and RS-232 logic signals.
The number of hit SciFis is required to be one for each layer when the incident position is determined. Here, both charged particles converted from the photon beam are expected to come to the same
SciFi region. One of them may, however, escape the active area of the SciFi hodoscopes due to the multiple scattering, complete energy loss, or other effects. In this case measured intensity map may be
distorted. Since the distortion mainly comes from the low-energy electrons or positrons converted from4
the untagged photon, the intensity map for the tagged photon beam is note deteriorated, which is estimated by a Monte Carlo simulation based on GEANT4 [14]. The details of the simulation results aredescribed elsewhere [10].
To estimate the number of coincidence signals with respect to the photon tagging signals, a sideband background-subtraction method is utilized. The background timing of the tagging signal is 165 ns(33 clock cycles) delayed with respect to the prompt timing. The harmonic number of the BST ringis 83 and the radio frequency is 500.14 MHz [4], which gives approximately 165.95 ns as a revolution
period. Fig. 2 shows the typical beam profile in coincidence with the 81st photon-tagging channel atthe circulating electron energy of 1.3 GeV. The details of the DAQ for the photon monitor are described
elsewhere [15, 16].

Counts / 3 mm

Counts / 3 mm

30000

10000

10000
0

y (mm)

20000

20000

-20 -10 0 10 20x (mm)

0

20

25000

10

20000

0

15000
10000

-10

5000

-20
-20 -10 0 10 20
y (mm)-20 -10 0 10 20x (mm)

Fig.2. Typical beam profile in coincidence with the 81st photon-tagging channel at a circulating
electron energy of 1.3 GeV. The left and central panels show the x and y distributions,and the right panel shows the two-dimensional profile. The curves in the left and central
panels show the fitted Gaussian functions.
The photon beam profiles were measured for different intensities and different photon energies. The
measured values for the mean and width in x and y distributions are the same for different conditions.
The variations of the mean and width in a spill was also measured. The photon beam spot moving in the+x to −x direction with respect to the radiator motion from −x to +x was observed. This is because thehorizontal position deviation from the center gives a negative momentum vector px /p deviation for theelectrons coming to the radiator position in the BST ring [4]. The spot moved by approximately 3 mm inx with respect to the elapsed time in a spill. The details of the various photon-beam profiles measured
are discussed elsewhere [7, 16].

§ 4. Summary

We have developed a fast profile monitor for high-intensity bremsstrahlung photon beams at ELPH.

The positions of photons producing electron-positron pairs at the converter are determined by the developed logic module, MPLM4X, with an FPGA chip, Spartan-6. No intensity and tagging energy dependences were observed in the measured beam profile.

5

Acknowledgments
The authors wish to thank the ELPH accelerator staff for providing the primary electron beamin the stable condition. This work was supported in part by Grants-in-Aid for Scientific Research (A)(24244022), and for Scientific Research (C) (26400287).

References[1]

H. Yamazaki et al.: Nuclear Instruments and Methods in Physics Research Section A 536, 70(2005).

[2]

T. Ishikawa et al.: Nuclear Instruments and Methods in Physics Research Section A 622, 1 (2010).

[3]

T. Ishikawa et al.: Proceedings of the 10th International Workshop on the Physics of Excited Nucleons (NSTAR2015), JPS Conference Proceedings 10, 031001 (2016);
T. Ishikawa et al.: Proceedings of the XV International Conference on Hadron SpectroscopyHadron 2013, PoS (Hadron 2013) 095;
T. Ishikawa et al.: Proceedings of the 20th International IUPAP Conference on Few-Body Problemsin Physics, Few Body Systems 54, 1047 (2013);
T. Ishikawa et al.: Research Report of LNS, Tohoku University, 42&43, 1 (2011).

[4]

F. Hinode et al.: Proceedings of 2005 Particle Accelerator Conference, 2458 (2005);
F. Hinode et al.: Proceedings of 11th International Conference on Synchrotron Radiation Instrumentation (SRI2012), Journal of Physics: Conference Series 425, 072011 (2013).

[5]

M. Nanao, T. Ishikawa, and H. Shimizu, Research Report of LNS, Tohoku University, 36, 56 (2003).

[6]

H. Fujimura et al.: Research Report of LNS, Tohoku University, 42&43, 56 (2011).

[7]

T. Ishikawa et al.: Nuclear Instruments and Methods in Physics Research Section A 811, 124(2016).

[8]

T. Ishikawa et al.: Nuclear Instruments and Methods in Physics Research Section A 694, 348(2012).

[9]

J.E. Moyal, Philosophical Magazine 46 (1955) 263;
M.D. Marucho, C.A. Garcia Canal, H. Fanchiotti, International Journal of Modern Physics C 17
(2006) 1461.

[10] Y. Tsuchikawa, S. Kido, and T. Ishikawa: Internal GeV-γ analysis note HD No. 384T (2015).
[11] ELPH annual report 2011–2013, Tohoku University, 194 (2014);
I. Nagasawa and T. Ishikawa: Internal GeV-γ analysis note HD No. 380C (2015).
[12] Spartan-6 website: ⟨http://www.xilinx.com/products/silicon-devices/fpga/spartan-6.html⟩.

[13] ISE

WebPACK

webpack.html⟩.

website:⟨http://www.xilinx.com/products/design-tools/ise-design-suite/ise-[14] S. Agostinelli, et al., Nuclear Instruments and Methods in Physics Research Section A 506 (2003)
250-303;
J. Allison, et al., IEEE Trans. on Nucl. Sci. 53 (2006) 270-278;

6Geant4 website ⟨http://geant4.cern.ch/⟩.

[15] T. Ishikawa: Internal GeV-γ analysis note HD No. 386T (2015).
[16] Y. Matsumura and T. Ishikawa: Internal GeV-γ analysis note HD No. 391T (2015).

ELPH Annual Report, Tohoku University (2015)

7(ELPH Experiment : #2803, #2844)

Upgrade plan of the FOREST experiments at ELPH
T. Ishikawa1 , H. Fujioka2 , Y. Honda1 , Y. Inoue1 , K. Itahashi3 , H. Kanda4 ,H. Kawai5 , Y. Matsumura1 , K. Maeda4 , M. Miyabe1 , N. Muramatsu1 ,H. Ohnishi3 , K. Ozawa6 , M. Sasagawa1 , H. Shimizu1 , K. Shiraishi1 ,M. Tabata5 , A.O. Tokiyasu1 , and Y. Tsuchikawa1
1

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

Department of Physics, Kyoto University, Kyoto 606-8502, Japan
3

4

Department of Physics, Tohoku University, Sendai 980-8578, Japan
5

6

Nishina Center, RIKEN, Wako 351-0198, Japan

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

Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization(KEK), Tsukuba 305-0801, JapanThe next generation FOREST experiments are planed to reveal the non-perturbative QCD phenomena. The main objective of the first experiment is to determine the η-n scattering length using theγd → pηn reaction. The photon beam with energies around 950 MeV can give the recoilless condition ofη mesons by detecting the protons at 0◦ . The effects of the the η-neutron final-state interaction must be

enhanced due to the small relative momentum between an η meson and a residual neutron. We placea bending magnet, which has been transported from KEK, behind FOREST to measure the forwardemitted protons. The similar experimental setup can perform an experiment to search for η-mesic nuclei, which are good probes to explore the properties of a nucleon resonance N (1535)S11 in the nuclear
medium. It should be noted that the resonance is speculated to be the chiral partner of the nucleon. In
this report, the planned FOREST experiment is presented.

§ 1. Introduction

The hadron-hadron interaction is a subject of great interest in the non-perturbative quantum chro-modynamics (QCD) domain. QCD is the fundamental theory of the strong interaction, and the hadronhadron interaction is described in principle by quark and gluon dynamics. Owing to the large running
QCD coupling constant, little is known for the QCD solution at low energies, where hadrons as colorneutral objects play an important role in effective theories or models.
Among the two-body dynamincs of the meson-nucleon systems, the interaction between the η meson and the nucleon (N ) is not well determined although it has been found to be attractive [1]. Neither
direct η-n scattering experiments using η beams nor X-ray measurements from η-mesic atoms canbe performed because the η meson is neutral and unstable. The η-N scattering length aηN has been
extracted using coupled-channel analyses [2–5] from the differential and total cross sections for the8πN → ηN and γN → ηN reactions together with the πN → πN scattering and γN → πN photoproduction reactions. Although the imaginary part of aηN is found to be ∼ 0.26 fm for different analyses, its

real part is scattered in a wide range from 0.4 to 1.1 fm. Another analysis of the np → ηd process witha three-body treatment of the final state [6, 7] gives 0.4–0.6 fm for the real part of aηN . Although a new

analysis using π + d → ηpp reaction is proposed [8], the corresponding experiment has not been carriedout at this moment. It should be noted that the existence of the exotic η-mesic nuclei can highly dependon the value of the real part of aηN [9]. The numerical values obtained so far for aηN are summarized
in Ref. [10]. We plan to conduct a new η photoproduction experiment [11] for the determination of the
η-n low-energy scattering parameters at ELPH, Tohoku University.
The modification of hadrons (a decrease of mass, a broadening of the width, and so on) in the nuclear medium is another issue of the next generation FOREST experiments. Since the nucleon resonance
N (1535)S11 is speculated to be the chiral partner of the nucleon, the nucleon N (938)P11 and N (1535)S11
become a degenerate state when chiral symmetry is restored. Even in a nucleus, the masses and difference of them are expected to decrease due to the partial restoration of the symmetry. The cross sectionsof η photoproduction from C and Cu were measured at Eγ = 600–1100 MeV to investigate the behaviorof the S11 resonance in a nucleus [12]. The angular and momentum distributions of η mesons are inquantitative agreement with the Quantum Molecular Dynamics (QMD) model calculations in a wide
range. An enhancement from the calculation is observed only in the ratio of the total cross sections
σCu /σC near the threshold as shown in Fig. 2 of Ref. [12], which can be explained by a simple toy modelthat takes into account the mass decrease of S11 and the change of the ηN phase volume. Other effects
can also explain this enhancement, however. Thus, we plan to search for η-nucleus bound/resonancestates to discuss in-medium properties of S11 more clearly.
An η-mesic nucleus was predicted by Haider and Liu [9, 13], and systematically studied by Chiang,
Oset and Liu [14]. No clear conclusion for η-nucleus bound state has been obtained in spite of someexperimental efforts [15] for investigating the η-N interaction in detail. The η mesons in the nuclear
medium are expressed by mixing of the η meson and the S11 -particle and P11 -hole excitation states [16].
The particle-hole mode is 50 MeV higher than the mesonic one, and the level crossing of these modes
are expected due to the degeneracy of S11 and P11 in the nuclear medium. The level crossing gives boththe bound and resonance states of the η-nucleus system. Therefore, not only η-nucleus bound states
but also resonance ones are affected by the in-medium properties of S11 . The expected energy spectra
for the η-nucleus system obtained by the γA → pη(A − 1) reaction are calculated with/without thelevel crossing in Ref. [16]. The experimentally obtained spectrum is important for understanding thein-medium properties of S11 although it does not have a prominent peak. The signal of the level crossing
in a nucleus is expected to give some structure in the resonance region.

§ 2. Upgrade experiments

To determine the η-n low-energy scattering parameters or to search for η-mesic nucleus states, weplan to carry out the experiments by using the photon beam around 950 MeV [17, 18] which satisfies

9
the recoilless condition of η mesons by detecting the protons at 0◦ [16]. The small relative momentum
between an η meson and a residual neutron or nucleus makes the probability higher giving the η-nfinal-state interaction or forming the η-nucleus bound/resonance states, respectively. Fig. 1 shows theexperimental setup of the next generation FOREST experiments. The details of the FOREST detector
is described elsewhere [19]. The forward scattered proton is momentum-analyzed with a bending magnet (transported from the low energy ring of KEKB) behind FOREST. The trajectory is planned to bemeasured with two planar drift chambers, and the time of flight will be measured with plastic scintillator hodoscopes . The additional e/π and π/K separations are made using SF5 lead glass and aerogel
Cherenkov counters, respectively.

proton emitted at 0 deg
SF5 for e/πγ γ

RPC or PS
DC
AC for π/Κphoton beam
Ν

FOREST

forward proton spectrometerFig.1. Experimental setup of the next generation FOREST experiments. The momentum andtime of flight of the proton scattered at 0◦ are measured through a bending magnet. The
forward emitted proton is momentum-analyzed with a bending magnet behind FOREST.
The trajectory is measured with two planar drift chambers, and the time of flight is measured with plastic scintillator hodoscopes. The additional e/π and π/K separations are
made using SF5 lead glass and aerogel Cherenkov counters, respectively.

2.1 Determination of the η-n scatering length
The planned FOREST experiment has an ideal condition to determine the η-n scattering parameters since it gives a small relative momentum between η and n and large relative momenta between ηand p and between n and p. Only the η-n final-state interaction affect the yield of the reaction. Fig. 2
shows the diagram of the γd → pηn reaction for determining the η-n scattering length. The advan-

tages in the kinematics of the new FOREST experiment for the aηn determination are confirmed byNakamura and Kamano [20] using the direct coupled channel (DCC) model [21].
To check the feasibility of the experiment, the relative momentum distribution without any finalstate interaction is estimated. Fig. 3 shows the relative momentum distribution between an η meson anda neutron for the γd → pηn reaction. Events having the small η-n relative momentum are enhanced bydetecting the forward emitted protons with the spectrometer. An additional enhancement |1/aηn − ik|is expected owing to the final-state interaction between the η meson and the neutron.

−2

10

γ
η production

p

p

η

d
n

n
low-energy
ηn scatteringηFig.2. Diagrams for the γd → pηn reaction. The reaction is a good probe to determine ηnscattering length since the relative momentum between η and n is small and the depicted
diagram becomes dominant when the proton is measured at 0◦ .
2.2 Search for η-mesic nuclei
The experiment to search for η-mesic nuclei will be made in the similar experimental setup to thatfor determining the η-n scattering length. In addition to the forward proton measurement, we will detect a back-to-back π 0 N or ηN pair with the FOREST detector to suppress background processes. It
should be noted that the π 0 N or ηN invariant mass gives information on the S11 mass in a nucleus.
Since the gap of the bending magnet is 110 mm, the polar angle up to 0.6◦ is covered by the bending
magnet. Assuming the 20 mm thick carbon target with a density of 1.5 g/cm3 , an eighty-day measurement gives approximately 100 events in a 10 MeV bin for the differential cross section of 100 nb/sr·MeV.
The expected missing mass resolution is 3.8–6.1 MeV according to the assumed time resolution of the
proton detecting hodoscopes 0.05–0.10 ns since the photon beam tagging resolution is 0.5–2.5 MeV. The
photoproduction experiment for η-mesic nucleus search is complementary to the planned experiments
at J-PARC using the (π − , n) reaction [22].

§ 3. Other subjects

The subjects of the next generation FOREST experiments were discussed held from 23rd to 24th

May, 2016 [23]. The following is the list for other subjects to be studied in the next generation FOREST
experiments with a deuterium target:
1. determination of the Λ-n scattering length using the γd → K + Λn events,

2. investigation of the N ∆ and ∆∆ dibaryon states using the γd → π − X events, and

3. investigation of the ηpp states using the γd → π − X events.

There exist many physics subjects to be studied in the next FOREST experiments.

§ 4. Summary

The next generation FOREST experiments are planed to reveal the non-perturbative QCD phenom-

ena. The main subject of the first experiment is to determine the η-n scattering length aηn using theγd → pηn reaction. The 950 MeV photon beam and proton detection at 0◦ give the recoilless condition of

11

4500

45

4000

40

3500

35

3000

30

Counts / MeVCounts/deg

x 10 2

2500
2000
1500

25
20
15

1000

10

500

5

0

0

20

40

60

0

0

θ p (deg)

200
P(η-n) (MeV/c)400

Fig.3. Relative momentum distribution between an η meson and a neutron for the γd → pηnreaction. The number of counts are given for the 90 days in the same condition as the
FOREST2009D experiment. The left panel shows the distribution for all the events, andthe right shows the distribution for the events in which the proton is measured with thedetectors behind the spectrometer.
η mesons. The η-neutron final-state interaction can be studied thanks to the small relative momentum
between the η meson and the neutron. The detection of the forward emitted proton is essential for thisstudy. We place a bending magnet behind FOREST to measure the forward emitted protons. We canperform an experiment to search for η-mesic nuclei in the similar experimental setup. The η-mesic nuclei good probes to explore the properties of a nucleon resonance N (1535)S11 , which is speculated to be
the chiral partner of the nucleon, in the nuclear medium. We have many physics subjects to be studied
in the next FOREST experiments.

Acknowledgments
This work was supported in part by Grants-in-Aid for Scientific Research (A) (24244022), and for
Scientific Research (C) (26400287).

References[1]

Q. Haider, L. C. Liu: Physical Review C 66, 045208 (2002).

[2]

M. Batinić, I. Šlaus, A. Švarc, B.M.K. Nefkens, Physical Review C 51 (1995) 2310;
M. Batinić, I. Dadı́c, I. Šlaus, A. Švarc, B.M.K. Nefkens, T.-S.H. Lee, Physica Scripta 58 (1998) 15.

[3]

A.M. Green, S. Wycech, Physical Review C 55 (1997) R2167;
A.M. Green, S. Wycech, Physical Review C 60 (1999) 035208.

[4]

A. Sibirtsev, S. Schneider, Ch. Elster, J. Haidenbauer, S. Krewald, J. Speth, Physical Review C 65
(2002) 044007.

12
[5]

A.M. Gasparian, J. Haidenbauer, C. Hanhart, Physical Review C 68 (2003) 045207.

[6]

H. Garcilazo, M.T. Peña, The European Physical Journal A 38 (2008) 209.

[7]

H. Calén et al., Physical Review Letters 79 (1997) 2642;
H. Calén et al., Physical Review Letters 80 (1998) 2069.

[8]

H. Fujioka, Acta Physica Polonica B 41 (2010) 2261;
H. Garcilazo, M.T. Peña, Physics Letters B 696 (2011) 386.

[9]Q. Haider, L.C. Liu, Physics Letters B 172 (1986) 257.

[10] Q. Haider and L.C. Liu, International Journal of Modern Physics E 24 (2015) 1530009[11] T. Ishikawa, et al., ELPH-2803 letter of intent (2014);
T. Ishikawa, et al., ELPH-2844 experiment (2016).
[12] T. Kinoshita et al.: Phys. Lett. B 639, 429 (2006).
[13] Q. Haider and L. C. Liu: Physical Review C 34, 1845 (1986).
[14] H. C. Chiang, E. Oset, and L. C. Liu, Physical Review C 44, 738 (1991).
[15] R.E. Chrien et al.: Physical Review Letters 60, 2595 (1988);
M. Pfeiffer et al.: Physical Review Letters 92, 252001 (2004).
[16] H. Nagahiro, D. Jido, S. Hirenzaki: Nuclear Physics A 761, 92 (2005);
D. Jido et al.: Nuclear Physics A 811, 158 (2008).
[17] T. Ishikawa, et al., Nuclear Instruments and Methods in Physics Research Section A 622, 1 (2010).
[18] T. Ishikawa, et al., Nuclear Instruments and Methods in Physics Research Section A 811, 124(2016).
[19] T. Ishikawa et al.: Nuclear Instruments and Methods in Physics Research Section A (2016),
http://dx.doi.org/10.1016/j.nima.2016.06.054;
T. Ishikawa, et al., Proceedings of the 10th International Workshop on the Physics of Excited Nucleons (NSTAR2015), JPS Conference Proceedings 10, 031001 (2016);
T. Ishikawa, Proceedings of the XV International Conference on Hadron Spectroscopy-Hadron2013, PoS (Hadron 2013) 095;
T. Ishikawa, et al., Proceedings of the 20th International IUPAP Conference on Few-Body Problems in Physics, Few Body Systems 54, 1047 (2013).
[20] S.X. Nakamura and H. Kamano: private communication.
[21] H. Kamano et al.: Physical Review C 88, 035209 (2013).
[22] K. Itahashi et al.: Letter of Intent for J-PARC ⟨http://www.j-parc.jp/NuclPart/pac/0707/pdf/
LoI-itahashi.pdf⟩.
[23] FOREST workshop: ⟨http://www.lns.tohoku.ac.jp/~hadron/mbr/ishikawa/forest16.php⟩.

ELPH Annual Report, Tohoku University (2015)13(ELPH Experiment : #2808)

A beam test of a charge-to-time converting leading-edge
discriminator for plastic-scintillator signals
T. Ishikawa1 , Y. Honda1 , Y. Inoue1 , H. Kanda2 , S. Kido1 , Y. Matsumura1 ,M. Miyabe1 , H. Shimizu1 , K. Shiraishi1 , A.O. Tokiyasu1 , Y. Tsuchikawa1 ,and H. Yamazaki1
1Research Center for Electron Photon Science (ELPH), Tohoku University, Sendai 982-0826,
Japan
2

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

A charge-integrating analog-to-digital converter (ADC) is too expensive only for monitoring of thegain and applying a pulse-height time-walk correction since it requires a long delay cable for each channel. Recently, a multi-hit time-to-digital converter (TDC) module is available such as CAEN V1190 and
V1290, which can digitize both the timings of the leading and trailing edges of signals. We have developed a charge-to-time converting (QTC) leading-edge discriminator for plastic-scintillator signals incooperation with Fuji Diamond International Co. Ltd. (FDI). A test of a prototype 1CH QTC discriminator, FDI 1370, is reported in the previous annual report [1]. In this report, a beam test of a manufactured
16CH QTC discriminator, FDI GeVγ-1370, is presented.

§ 1. Introduction

To use a charge-integrating analog-to-digital converter (ADC or QDC), each analog signal should

be delayed with a long coaxial cable so that the analog signal starts after the gate signal opens. The
number of channels to be measured in nuclear physics experiments is increasing, and the trigger logic
becomes more complicated and requires a longer delay for each analog signal. Nowadays, we can easily
use multi-hit TDC modules, which can record both the leading and trailing edges of logic signals, such as
CAEN V1190 and V1290. A charge-to-time converting (QTC) leading-edge discriminator, which outputs
the logic signal with a width giving the charge integration of an input signal, can remove QDC modules.
We have developed QTC discriminator for fast plastic-scintillator signals to monitor the gain and toobtain the pulse-height time-walk corrected timing. A test of a prototype 1CH QTC discriminator, Fuji
Diamond International Co. Ltd. (FDI) 1370, is reported in the previous annual report. Here, a beam testof a manufactured 16CH QTC discriminator, FDI GeVγ-1370, is presented.

§ 2. Experimental setup

The time resolution was measured for a plastic scintillator (PS) (ELJEN Technology EJ-212) with asize of 20 mm (W) × 30 mm (H) × 30 mm (T) at the electron beamline for testing detectors [2, 3] at the

Research Center for Electron Photon Science (ELPH), Tohoku University. The PS was connected to two

14
photo-multiplier tubes (PMTs), Hamamatsu Photonics H6410. The PS was located at 5.9 m downstreamof the center of RTAGX to reduce the effect of its fringing field. In front of the PS, two scintillating fibers(SciFis) with a cross-section of 3 × 3 mm2 were placed in a plus form to determine the impact positionof the electrons. The distance between the SciFis and PS was approximately 55 mm. Each SciFi wasconnected to a PMT, Hamamatsu Photonics R4125G. Figure 1 shows the experimental setup for the time
resolution measurement.
PS2
R4125G

+y
+x
+z

H6410
PS1

PS4

PS3

Fig.1. Experimental setup. The upstream two SciFis are used to determine the incident positionof the electron beam. The downstream PS measures 20, 30, and 30 mm in width, height,
and thickness, respectively. The connected PSs are R4125Gs and H6410 for two SciFis
and PS, respectively.
An output analog signal from each PMT was delivered to the VME based data acquisition (DAQ)
system located in the GeV-γ counting room through a 50 m 3D-FB coaxial cabel. Each signal was divided
into two, and one was input to a charge-integrating ADC module, REPIC RPV-171, through a 200 ns
cable delay. The other was input to a QTC discriminator after the attenuation (0–14 dB). The NIM outputof the QTC discriminator was input to a multi-hit TDC module, CANE V1290N. The 1/83 prescaled RF
signal (500.14 MHz) was also input to V1290N. Figure 2 shows the circuit diagram for the time resolution
measurement. The trigger of DAQ was a logic OR between a coincidence signal of the two SciFi signals
and 100 Hz clock signal, and was made by an FPGA-based logic module, MPLM4X [4, 5]. The gate width
for RPV-171 was 100 ns, and readout from the RPV-171 and V1290 was made 10 µs after the trigger
formation.
The measurement was carried out from 14 to 15 in May 2015. After the adjustment of the attenuation factors and supplied voltages and so on, three runs (run00078, 00080, and 00081) were acquired. The
numbers of events collected were 199999, 107187, and 94859, and those of the clock-triggered eventswere 169979, 92399, and 82255 for run00078, 00080, and 00081, respectively. The RTAGX current is set

to 375 A corresponding the electron momentum of 707 MeV/c. The 200-µm thick W converter was used
for producing the electron beam. The singles rates for the upstream and downstream SciFis were 0.4
and 1.7 kHz, and those for the PS signals were 2.8 and 2.8 kHz. The rate was 130 Hz for the coincidence
signals of the two SciFis.

15

200 nsPS 1 or 2

Divider

RPV-171

Delay

Attenuator

ADC 0

GeVγ-1370
QTC Discriminator

ADC 0
MPLM4X

Logic FanIn
FanOut

ADC 0
TDC
V1290
RPV-171

200 nsPS 3 or 4

Divider

Delay

Attenuator

ADC 0

GeVγ-1370
QTC Discriminator

ADC 0
TDC
V1290

RF

ADC 0
TDC
V1290

Fig.2. Circuit diagram for the time resolution measurement. Each signal is divided into two,and one is input to an RPV-171 ADC module through a 200 ns cable delay. The other isinput to a QTC discriminator after the attenuation. The NIM output of the QTC discriminator is input to a V1290N multi-hit TDC module. The 1/83 prescaled RF signal (500.14
MHz) is also input to V1290N. The trigger of DAQ is handled with the MPLM4X logic
module.

§ 3. Time resolution

The pedestal of each signal is described in subsection 3.1. The measured charge integration is

discussed in subsection 3.2, here the correlation between the charge integration and QTC output width isgiven. The measured timings corrected by the charge integration and QTC output width are presented insubsections 3.3 and 3.4, respectively. Finally, the time fluctuation of the delivered RF signal is discussed
in subsection 3.5.
3.1 Pedestal
The pedestal distribution corresponding to the zero energy distribution was estimated for eachchannel for each run by selecting the events in which any TDC values were recorded for two SciFi and
two PS signals. Figure 3 shows the typical pedestal distributions for 4 signals. The width of the upstream
SciFi signal was very broad. A horizontally placed R1425G PMT was often affected by a noise probably
due to the fringing field of the RTAGX magnet.

The centroid and width of the pedestal distribution for each channel for each run were given by

the average and standard deviation of the distribution. The evaluation of the average and standard
deviation was made in the range [µ − 10 channel, µ + 10 channel) five times, and the final values wereused. Figure 4 shows the centroid and width as a function of the run number for each signal. The
centroids and widths for all the signals were stable during all the measurements.

16

x 10
10000

1200

Counts / channel

4000
2000

50
100
150
ADC (channel)

x 10

0

10000

50
100
150
ADC (channel)

200

50
100
150
ADC (channel)

200

4

8000

800

6000

600

4000

400

2000

200
0

0

200

Counts / channel

Counts / channel

6000

3

1000

2

8000

Counts / channel

18000
1
16000
14000
12000
10000
8000
6000
4000
2000
0
x 10 20

0

50
100
150
ADC (channel)

200

0

0

Fig.3. Typical pedestal distributions for 4 signals (run00078). The signal is described in eachpanel, PS 1 and 2 denote the two SciFi signals, and PS 3 and 4 denote the two PS signals.
The vertical lines show the boundaries for evaluating the centroids and widths.
3.2 Charge integration and QTC output width
The charge integration Qi for i-th channel was determined by an equation:
Qi = αQ (Ai − µi ) ,(1)

where µi stands for the centroid of the corresponding pedestal distribution. The αQ = 0.25 pC/channel(catalog value) is the channel-to-charge converting coefficient. The events were selected in which boththe leading- and trailing edge TDC values were recorded for two SciFi and two PS signals. Figure 5
shows the measured charge distributions for 4 signals. Together with the measured charge distributions
for all the events, those are shown for the events in which the corresponding leading-edge TDC value
is recorded, and for the events in which all the leading-edge values are recorded in the four signals.
Except for the charge distribution for the upstream SciFi signal, the charge distributions have a peak at
0 for the events n which the corresponding leading-edge TDC value is recorded. This suggests that thediscriminator threshold is too low to exclude the dark current events. Anyway the penetration conditionis clearly obtained by selecting the events in which all the leading-edge values are recorded in the four
signals.
Next, the correlation between the measured charge integration and QTC output width was investigated for each channel. Here, the events were selected in which all the leading- and trailing-edge values

17

140

5
4

135

3

130

2

125

1

120
77
180

79
80
Run

81

3

6

170

5
4

165

3

160

2

155
150
77

0
82
7

Mean and Width

175

78

1

78

79
80
Run

81

0
82

175
170

7

2

6

Mean and Width

6

Mean and Width

145

7

1

165

5
4

160

3

155

2

150

1

145
77
165
160

78

79
80
Run

81

6

155

5
4

150

3

145

2

140
135
77

0
82
7

4

Mean and Width

150

1

78

79
80
Run

81

0
82

Fig.4. Centroid and width as a function of the run number for each signal. The signal is described in each panel, PS 1 and 2 denote the two SciFi signals, and PS 3 and 4 denote thetwo PS signals. The blue and red markers represent the centroid and width referring theleft and right axes, respectively.
are recorded in the four signals. Figure 6 shows the correlations for 4 signals between the measured
charge integration and QTC output width. The measured TDC value was corrected according to its leastsignificant 10 bits (V1290N S/N 247) [6]. The output width was given by the difference of the TDC values
corresponding to the leading- and trailing-edges. To avoid the bit rotation effects, the negative difference
was corrected by adding 2 × 1024 × 1024 channels. The coefficient 24.4138 ps/channel was multiplied

to the width to convert the channel to time taking into account the fact that the interval of the 1/83
prescaled 500.14 MHz RF signal was 6797.531 channels, which is discussed below in subsection 3.5).
Two SciFi signals have a good linearity between the charge integration and QTC output width in thewhole region. While the two PS signals lose a linearity when the input charge to the QTC discriminator
exceeds 20 pC, here it should be noted that the attenuation factor for two PS signals were 14 and 9dB.
The output width was shorter than expected in such case. The correlation as shown in Fig,ure 6 wasassumed to be expressed as
Wi = fiW (Qi ) = aQ Qi + bQ Q2i

(2)

18

10

PS 1

3

10 2
10
1

0

20

40
60
80
Charge Q1 (pC)

10
0

100
200
300
Charge Q3 (pC)

10

PS 2

3

10 2
10
1

0

10 4

PS 3

3

10 2

1

100

Counts / pC

Counts / pC

10 4
10

10 4
Counts / 5 pC

Counts / 0.25 pC

10 4

400

10

50
100
150
Charge Q2 (pC)

200

PS 4

3

10 2
10
1

0

100
200
300
Charge Q4 (pC)400

Fig.5. Measured charge distributions for 4 singlas (run00078). The signal is described in eachpanel, PS 1 and 2 denote the two SciFi signals, and PS 3 and 4 denote the two PS signals.
The black, blue, and red histograms represent the charge distributions for all the events,
for the events in which the corresponding leading-edge TDC value is recorded, and for the
events in which all the leading-edge values are recorded in the four signals, respectively.
where Wi stands for the QTC output width and Qi denotes the charge integration for each channel. The
obtained parameters aQ and bQ by fitting the equation (2) to the data were
)
 (
2

 17.902(0) ns/pC, −0.021880(29) ns/pC for SciFi 1,


(
)


 4.689(0) ns/pC, −0.000782(2) ns/pC2
for SciFi 2,()(aQ , bQ ) =
3.740(0) ns/pC, −0.002418(0) ns/pC2
for PS 1, and


(
)


 2.151(0) ns/pC, −0.000620(0) ns/pC2
for PS 2.

(3)

Here, the fitting procedure was made run by run for each channel, and the parameter was obtained byaveraging the fitting parameters for different runs.
The fluctuation of the QTC output width for each channel was estimated. Here, the residual of thewidth δW was given as a difference between the measured width and evaluated width from the charge
integration:
δW = Wi − fiW (Qi )(4)assuming the equations (2) and (3). The widths of the residuals are broad for two SciFi signals, andthose are narrow for two PS signals. The centroid µW and width σW were obtained by fitting theGaussian function to each residual distribution. The fitting procedure was repeated five times in the

500
450
400
350
300
250
200
150
100
50
0

1
Width W2 (ns)

Width W1 (ns)

19

0

1200

40 60 80 100 120
Charge Q1 (pC)

3

800
600
400
200
0

0

2

0

1200

100

200 300 400
Charge Q3 (pC)

500

20

40 60 80 100 120
Charge Q2 (pC)

41000
Width W4 (ns)1000
Width W3 (ns)

20

500
450
400
350
300
250
200
150
100
50
0

10 2

800
600

10

400
200
0

0

100 200 300 400
Charge Q4 (pC)500

1

Fig.6. Correlations between the charge integration and QTC output width for 4 signals(run00078). The signal is described in each panel, PS 1 and 2 denote the two SciFi signals, and PS 3 and 4 denote the two PS signals. The red curves show the fitted functions
expressed in Eq. (2).
350

1

300

200

Counts / nsCounts / ns

250
150
100
50

250
200
150
100
50

0

-100

0
100
Residual (ns)

3

0

1400
1200

-100

0
100
Residual (ns)

-100

0
100
Residual (ns)4Counts / ns

1000

Counts / ns

1600
1400
1200
1000
800
600
400
200
0

2

800
600
400
200

-100

0
100
Residual (ns)0

Fig.7. Fluctuations of the QTC output width for 4 signals (run00078). The signal is described ineach panel, PS 1 and 2 denote the two SciFi signals, and PS 3 and 4 denote the two PS
signals. The red curve shows the fitted Gaussian in each panel. The vertical green lines
show the boundaries for the fitting regions.

20
range [µW − 2σW , µW + 2σW ), and the final values were adopted. Table 1 summarizes the centroid µW
and width σW for each signal for each run.

Table 1. Centroid µW and width σW for each signal for each run by fitting a Gaussian function
to the residual distribution for the QTC output width.
鐃緒申鐃緒申

00078
00080
00081

PS 3
µW (ns) σW (ns)−0.9(2)34.0(1)+0.6(3)33.9(2)+0.0(3)32.5(2)PS 4µW (ns) σW (ns)−6.4(2)28.8(2)−5.6(3)28.6(2)−5.6(3)28.7(3)PS 3µW (ns) σW (ns)−0.6(0)5.3(0)−0.7(0)5.3(0)−0.7(0)5.2(0)PS 4µW (ns) σW (ns)−0.7(0)6.3(0)−0.6(0)6.3(0)+0.1(0)6.3(0)

3.3 Measured timing corrected by the charge integration
The QTC discriminator is a kind of leading-edge discriminators. The leading-edge timing is delayed
from the actual response timing according to the pulse-height of the input signal. The large pulse islikely to respond earlier because the time interval is shorter between the response and exceeding over
the threshold. This effect is often called pulse-height time-walk (PHTW). Here, the PHTW-corrected
timing is discussed using the charge integration. As same as subsection 3.2, the events were selected inwhich both the leading- and trailing edge TDC values were recorded for two SciFi and two PS signals.
At the first stage, the time difference of two PS responses was estimated without any PHTW correction. Figure 8 shows the time difference of two PS responses. The PHTW effect is more or less canceledin the time difference of two PS responses since the charge integration in a PS signal is larger when thatin the other PS becomes is large. The width of the time difference σt is as small as 78 ± 1 ps (run00078),

77 ± 1 ps (run00080), and 77 ± 1 ps (run00081) even when the timing is evaluated without any PHTW
correction. Here, σt s was given by fitting a Gaussian function to the time difference distribution in therange [µt − 2σt , µ + 2σt ) where µt denotes the centroid of the distribution. The fitting procedure wasrepeated five times, and the final values were adopted. The µt s obtained wer 904 ± 1 ps for all the runs.

Counts / 0.01 ns

1200
1000
800
600
400
200
0

-2

-1

0
1
t3-t4 (ns)2

Fig.8. Time difference of two PS responses (run00078). Here, the timing is given without any
PHTW correction. The red curve shows the fitted Gaussian function.

21
To get the PHTW behavior for the two PS signals, the time interval was investigated between a PS
timing and an average timing of two latest RF signals. The average timing of two latest RF signals wascalculated in the following way:
1. the time interval of the 1/83 prescaled RF signal was determined,
2. the first 1/83 prescaled RF signal timing was calculated using time interval (bit rotation was correctly taken into account),
3. the average of all the first 1/83 prescaled RF signal timings determined in 2 was determined (standard RF timing), and4. the time interval between the standard RF signal and the average of two PS response timings wasdetermined in a unit of half period of the RF signal.
Figure 9 shows the correlation between the response timing of a PS signal and the charge integration.
Here, the response timing is given in the elapsed time from the average timing of two latest RF signals,
and the response timing is given without any PHTW correction. Two loci are observed because theaverage of the two PS signal timings are not correctly determined.

1.5

1.5

1

1

t4-tRF (ns)2t3-tRF (ns)

2

0.5

0.5

0

-0.5
-1

10 2

10

0

-0.5
0

100

200 300 400
Charge Q3 (pC)

500

-1

0

100 200 300 400
Charge Q4 (pC)

500

1

Fig.9. Correlation between the response timing of a PS signal and the charge integration(run00078). The left panel shows that for the first PS signal (PS3), and the right showsthat for the second PS signal (PS4). Here, the response timing is given in the elapsed timefrom the average timing of two latest RF signals, and the response timing is given without any PHTW correction. The data are compared with the equation (5) with parameters(6).
The PHTW function is assumed to be expressed by a function of the charge integration Qiiti − tRF = fPHTW(Qi ) = ti0 − αi tanh (βi Qi ) ,(5)where ti − tRF denotes the response timing (the elapsed time from the average timing of two latest RF
signals). The initial parameters were determined by hand: (1.4 ns, 3.0 ns, 0.0025 pC−1 ) for PS3, and(ti0 , αi , βi ) = (2.5 ns, 2.8 ns, 0.0025 pC−1 ) for PS4.

(6)

The PHTW functions were also superimposed in Figure 9. It should be noted that the first and second

22
PS signals are described as PS3 and PS4 in all the figures. In the next step, the measured timing ti wasgiven using a PHTW correction:(7)i(Qi ).
ti ← ti − fPHTW

The elapsed time from the average timing of two latest RF signals was estimated again, the latest RF
signal timings were obtained using the average of the PHTW corrected timings for the two PS signals.
Figure 10 shows the re-estimated correlation between the response timing of a PS signal and the charge
integration. Only a locus is observed because the average of the two PS signal timings is correctly
determined. By fitting a function expressed in Eq. (5) to the data, the following parameters wereobtained:(ti0 , αi , βi ) = (1.577 ± 0.042 ns, 2.741 ± 0.066 ns, 0.00324 ± 0.00016 pC−1 ) for PS3, and (2.681 ± 0.051 ns, 3.128 ± 0.059 ns, 0.00249 ± 0.00011 pC−1 ) for PS4.

(8)

Here, the parameters are obtained by averaging those for the three runs.

1.5

2

1

1.5

t4-tRF (ns)2.5

t3-tRF (ns)

2

0.5
0

1

10

0.5

-0.5
-1

10 2

0
0

100

200 300 400
Charge Q3 (pC)

500

-0.5

0

100 200 300 400
Charge Q4 (pC)5001

Fig.10. Re-estimated correlation between the response timing of a PS signal and the charge
integration (run00078). The left panel shows that for the first PS signal (PS3), and theright shows that for the second PS signal (PS4). Here, the response timing is givenin the elapsed time from the average timing of two latest RF signals, and the response
timing is given without any PHTW correction. The data are compared with the equation(5) with parameters (8).
The initial PHTW functions may not well reproduce the average of the latest two RF timings. Thus,
the elapsed time from the average timing of two latest RF signals was re-calculated using parameter
expressed in Eq. (8), and the response timing was given without any PHTW correction. Figure 11 shows
the second re-estimated correlation between the response timing of a PS signal and the charge integration. By fitting a function expressed in Eq. (5) to the data, the following parameters were obtained: (1.842 ± 0.067 ns, 2.644 ± 0.052 ns, 0.00446 ± 0.00026 pC−1 ) for PS3, and(ti0 , αi , βi ) =(9) (2.911 ± 0.062 ns, 3.036 ± 0.052 ns, 0.00314 ± 0.00015 pC−1 ) for PS4.
Here, the parameters are also obtained by averaging those for the three runs.

23

1.5

2

1

1.5

t4-tRF (ns)2.5

t3-tRF (ns)

2

0.5
0

1

10

0.5

-0.5
-1

10 2

0
0

100 200 300 400
Charge Q3 (pC)

500

-0.5

0

100 200 300 400
Charge Q4 (pC)5001

Fig.11. Second re-estimated correlation between the response timing of a PS signal and thecharge integration (run00078). The left panel shows that for the first PS signal (PS3),
and the right shows that for the second PS signal (PS4). Here, the response timing
is given in the elapsed time from the average timing of two latest RF signals, and the
response timing is given without any PHTW correction. The data are compared withthe equation (5) with parameters (9).
The PHTW-corrected timings were obtained using the final parameters expressed in Eq. (9), andthe time difference distribution between the PHTW-corrected PS3 and PS4 timings were estimated.
Figure 12 shows the time difference distribution between the PHTW-corrected PS3 and PS4 timings.
34
The centroid µ34
t and width σt were obtained fitting a Gaussian function to the distribution in the34
34
34
range [µ34t − 2σt , µt + 2σt ). The fitting procedure was repeated five times, and the final values wereadopted. The parameters obtained were (−2.4 ± 0.5, 60.3 ± 0.5) ps for run00078,
34
34(µt , σt ) =(−1.1 ± 0.7, 59.8 ± 0.7) ps for run00080, and (+3.0 ± 0.7, 58.7 ± 0.7) ps for run00081.

(10)

The centroid is approximately 0 for all the runs, and the average width was 59.8 ± 0.3 ps. If the time

resolutions are common for the PS3 and PS4 signals, the time resolution is thought to be 42.3 ps.

Next, the elapsed time distribution of the PS 3 (PS 4) signal from the lated RF signal. Here, theresponse timing of the PS 3 (PS 4) signal is given using the PHTW correction with the parameters
expressed in Eq. (9), Figure 13 shows the elapsed time distribution of the PS 3 (PS 4) signal from thelated RF signal. The centroid µ3t (µ4t ) and width σt3 (σt4 ) were determined by fitting a Gaussian function
to the distribution. The fitting process was repeated five times in the range [µ3t − 2σt3 , µ3t + 2σt3 ) and[µ4t − 2σt4 , µ4t + 2σt4 ), and we adopted the final values. The obtained parameters µ3t , σt3 , µ4t , and σt4 were
(−23.3 ± 0.8, 99.7 ± 0.8, −21.9 ± 0.9, 106.4 ± 0.9) ps for run00078,


3
3
4
4
(µt , σt , µt , σt ) =(−25.3 ± 1.2, 101.1 ± 1.2, −25.4 ± 1.3, 106.5 ± 1.3) ps for run00080, and (11) (−22.6 ± 1.3, 99.8 ± 1.3, −26.4 ± 1.4, 103.6 ± 1.4) ps for run00081.

The average values of µ3t and µ4t were −23.6 ± 0.6 and −23.8 ± 0.7 ps, respectively. The average valuesof σt3 and σt4 were 100.1 ± 0.6 and 105.8 ± 0.7 ps, respectively. When the time resolution for the delivered24

Counts / 0.01 ns

1600
1400
1200
1000
800
600
400
200
0

-2

-1

0
1
t3c-t4c (ns)2

Fig.12. Time difference distribution between the PHTW-corrected PS3 and PS4 timings(run00078). The PHTW-corrected timings are obtained using the parameters in Eq. (9).
RF signal is extremely high, the obtained widths σt3 and σt4 are much larger than the approximate time
resolution 42.3 ps for PS 3 and PS 4. This inconsistent time resolutions will be discussed below insubsection 3.5.

800

800

Counts / 0.01 ns

1000

Counts / 0.01 ns

1000

600

600

400

400

200
0

200

-1.5 -1 -0.5 0 0.5
t3c-tRF (ns)

1

1.5

0

-1.5 -1 -0.5 0 0.5
t4c-tRF (ns)1

1.5

Fig.13. Elapsed time distributions of the PS 3 (left) and PS 4 (right) signal from the lated RF
signal (run00078). The PHTW-corrected timings with the parameters (9) are used for the
response timings of the PS 3 and PS 4 signals. The elapsed time distributions without
any PHTW correction are also plotted in cyan.

3.4 Measured timing corrected by the QTC output width
The PHTW-corrected timing using the charge integration is discussed in subsection 3.3. Here, the
PHTW-corrected timing using the QTC output width is discussed in this subsection. At first, the average
PHTW-corrected timing of the PS 3 and PS 4 signals are estimated with the parameters expressed in
Eq. (9), and the correlation between the response timing of a PS signal and the QTC output width isinvestigated. Figure 14 shows the correlation between the response timing of a PS signal and the QTC
output width. Here, the response timing is given as the elapsed time from the average timing of two

25latest RF signals estimated without any PHTW correction. To give the PHTW equation as a function of
the QTC output width Wi , the PHTW function is assumed to be expressed sa()
i(Wi ) = ti0 − αi tanh βi fiQ (Wi )ti − tRF = fPHTW(12)

where ti − tRF denotes the elapsed time from the average timing of two latest RF signals. By fitting afunction expressed in Eq. (12) to the data, the following parameters were obtained: (1.796 ± 0.062 ns, 2.597 ± 0.081 ns, 0.00866 ± 0.00063 ns−1 ) for PS3, and(13)(ti0 , αi , βi ) = (3.013 ± 0.066 ns, 2.960 ± 0.057 ns, 0.00702 ± 0.00040 ns−1 ) for PS4.
Here, the parameters are also obtained by averaging those for the three runs.

1.5

2

1

1.5

t4-tRF (ns)2.5

t3-tRF (ns)

2

0.5
0

1

10

0.5

-0.5
-1

10 2

0
0

200

400 600 800 1000
Width W3 (ns)

-0.5

0

200

400 600 800 1000
Width W4 (ns)1

Fig.14. Correlation between the response timing of a PS signal and the QTC output width(run00078). Here, the response timing is given as the elapsed time from the averagetiming of two latest RF signals estimated without any PHTW correction. The red curves
show the fitted functions (12). The equation (5) with the parameters (9) is used for thedetermination of the latest two RF signal timings.
The PHTW-corrected timings were obtained using the final parameters expressed in Eq. (13), andthe time difference distribution between the PHTW-corrected PS3 and PS4 timings were estimated.
Figure 15 shows the time difference distribution between the PHTW-corrected PS3 and PS4 timings.
34
The centroid µ34
t and width σt were obtained fitting a Gaussian function to the distribution in the34
34
34
range [µ34t − 2σt , µt + 2σt ). The fitting procedure was repeated five times, and the final values wereadopted. The parameters obtained were
(−6.1 ± 0.5, 63.6 ± 0.5) ps for run00078,


34
34
(µt , σt ) =(−5.6 ± 0.7, 63.7 ± 0.5) ps for run00080, and (−3.9 ± 0.8, 63.1 ± 0.7) ps for run00081.

(14)

The centroid is approximately 0 for all the runs, and the average width was 63.5 ± 0.3 ps which is a little

bit poorer than the obtained value 59.8 ± 0.3 ps in subsection 3.3.

Next, the elapsed time distribution of the PS 3 (PS 4) signal from the lated RF signal. Here, theresponse timing of the PS 3 (PS 4) signal is given using the PHTW correction with the parameters

26

Counts / 0.01 ns

1400
1200
1000
800
600
400
200
0

-2

-1

0
1
t3c-t4c (ns)2

Fig.15. Time difference distribution between the two PS signals (run00078). The response timings are calculated by applying the PHTW correction with Eq. (5) with the parameters
expressed in Eq. (13).
expressed in Eq. (13), Figure 16 shows the elapsed time distribution of the PS 3 (PS 4) signal from thelated RF signal. The centroid µ3t (µ4t ) and width σt3 (σt4 ) were determined by fitting a Gaussian function
to the distribution. The fitting process was repeated five times in the range [µ3t − 2σt3 , µ3t + 2σt3 ) and[µ4t − 2σt4 , µ4t + 2σt4 ), and we adopted the final values. The obtained parameters µ3t , σt3 , µ4t , and σt4 were
(−35.2 ± 0.8, 100.4 ± 0.8, −30.1 ± 0.9, 107.7 ± 0.9) ps for run00078,


3
3
4
4
(µt , σt , µt , σt ) =(−38.1 ± 1.2, 101.9 ± 1.2, −33.9 ± 1.3, 107.8 ± 1.3) ps for run00080, and (15) (−34.6 ± 1.3, 100.3 ± 1.3, −32.7 ± 1.4, 106.9 ± 1.4) ps for run00081.

The average values of µ3t and µ4t were −35.8 ± 0.6 and −31.6 ± 0.7 ps, respectively. The average values ofσt3 and σt4 were 100.7 ± 0.6 and 107.6 ± 0.7 ps, respectively. The deviation the centroid from 0 is a little

bit larger than that in subsection 3.3, suggesting that the fitting function (12) with the measured QTC
output widths is not wors than the function (5) with the measured charge integrations. The obtained
values of 100.7 ± 0.6 and 107.6 ± 0.7 ps for σt3 and σt4 , however, are consistent with the values 100.1 ± 0.6

and 105.8 ± 0.7 ps obtained in subsection 3.3. This suggests that the QTC output width can be used forthe pulse-height time-walk correction instead of the charge integration.
3.5 Delivered RF signals
The PHTW-corrected timings given by the charge integrations are used in this subsection since they
are little bit better than those given by the QTC output widths. The time resolution between the PS 3
and PS 4 response timings is 59.8 ± 0.3 ps, that between the PS 3 and the latest RF signals is 101.6 ± 0.6

ps, and that between the PS 4 and the latest RF signals is 105.8 ± 0.7 ps. The time resolution σt34

between the PS 3 and PS 4 response timings are expressed by the intrinsic time resolutions for PS 3 σ3and PS4 σ4 :
(

σt34

)2

= σ32 + σ42 .

(16)

27

800

800

Counts / 0.01 ns

1000

Counts / 0.01 ns

1000

600
400
200
0

-1.5 -1 -0.5 0 0.5
t3c-tRF (ns)

1

1.5

600
400
200
0

-1.5 -1 -0.5 0 0.5
t4c-tRF (ns)1

1.5

Fig.16. Elapsed time distributions of the PS 3 (left) and PS 4 (right) signal from the lated RF signal (run00078). The PHTW-corrected timings with the parameters (13) are used for the
response timings of the PS 3 and PS 4 signals. The elapsed time distributions without
any PHTW correction are also plotted in cyan.
The time resolution σt3 between between the PS 3 and the latest RF signals is assumed using the intrinsic
RF time resolution σRF as
(

σt3

(

σt4

)2

2
= σ32 + σRF
, and

(17)

the time resolution σt4 between between the PS 4 and the latest RF signals is also assumed as)22= σ42 + σRF.

(18)

By solving the simultaneous three equations, the intrinsic time resolutions are obtained as(σ3 , σ4 , σRF ) = (36.8, 47.2, 94.7) ps.

(19)

Let consider the elapsed time of the average PHTW-corrected timing between PS3 and PS4 from thelatest RF signal. The width of the elapsed time distribution σtave is expressed by2(σtave ) =

)
1 ( 2
2
σ3 + σ42 + σRF
,
4

(20)

and σtave = 99.3 ps is expected. To confirm this, the elapsed time distribution of the average PHTWcorrected timing between PS3 and PS4 from the latest RF signal has been estimated using the parameters expressed in Eq. (9). Figure 17 shows the elapsed time distribution of the average PHTW-corrected
and width σtave are determinedtiming between PS3 and PS4 from the latest RF signal. The centroid µavet
− 2σtave , µave
+ 2σtave ). The fitting
by fitting a Gaussian function to the distribution in the range [µavettandprocedure has been repeated five times, and we have adopted the final values. The parameters µavet
σtave obtained are

ave
(µave
t , σt ) = (−23.8 ± 0.8, 97.0 ± 0.8) ps for run00078,
(−25.4 ± 1.2, 98.1 ± 1.2) ps for run00080, and (−25.0 ± 1.2, 96.0 ± 1.2) ps for run00081.

(21)

28
The average width is 97.0 ± 0.6 ps, and is consistent with the expected value 99.3 ps. When the obtained

value of 97.0 ± 0.6 ps is treated as a measured one, and the intrinsic time resolutions are estimatedagain from the four measured widths:(σ3 , σ4 , σRF ) = (37.2 ± 1.3, 46.8 ± 1.0, 93.7 ± 0.4) ps.

(22)

Counts / 0.01 ns

1000
800
600
400
200
0

-1.5 -1 -0.5 0 0.5 1(t3c+t4c)/2-tRF (ns)1.5

Fig.17. Elapsed time distribution of the average PHTW-corrected timing between PS3 and PS4
from the latest RF signal. The red curve shows the fitted Gaussian function. The elapsed
time distribution of the average timing between PS3 and PS4 without any PHTW correction from the latest RF signal is also plotted in cyan.
The reason why the intrinsic time resolution for the RF signal is poor as 93.7±0.4 ps is investigated.
The 1/83 prescaled RF signal was recorded 37–38 times event by event. The average µ83 and standard
deviation σ83 of the time interval was calculated for every event. Figure 18 shows the average µ83 andstandard deviation σ83 of the time interval of the 1/83 prescaled RF signal. The centroid and width
are given fitting a Gaussian function to the distributions. The fitting procedure is made fiver times in
the range [µ − 3σ, µ + 3σ), and we have adopted the final values. The centroid of the µ83 distribution

is 6797.531 ± 0.000 channel, and its width is 0.036 ± 0.000 channel for run00078. The centroid of theσ83 distribution is 1.162 ± 0.001channel, and its width is 0.157 ± 0.001 channel. The errors of thecentroids and widths in run00080 and 00081 are larger than those in run0078, but the parameters in
run00080 and 00081 are consistent with those in run0078. Because the time interval 6797.531 ± 0.000
channel corresponds to the time 83 × (500.14 MHz)−1

, the time-to-channel coefficient is found to be

24.414 ps/channel for the TDC values in the V1290N used. The fluctuation of µ83 is 0.036 channel, andσ84 is 1.162 ± 0.157 channel. The time resolution for the measurement of the delivered RF timings isfrom 1 to 2 channels. Since the RF timings are recorded 37–38 times for each event, the precision of thestandard RF timing determination is thought to be 0.17–0.35 channels corresponding to 4–8 ps.
The time resolution for the delivered RF signal is 4–8 ps, thus the obtained value σRF = 93.7 ps isthought to be the bunch length including the timing fluctuation in the Booster STorage (BST) ring [7].
The equilibrium bunch length σt at high energies is expressed byσt =αp σ E= 91.7 ps,
2πfs E

(23)

29

7000

25000

6000
Counts / 10 ps

Counts / 10 ps

20000
15000
10000
5000
0
6797

5000
4000
3000
2000
1000

6797.5
µ83

6798

0

0

0.5

1
σ83

1.5

2

Fig.18. The average µ83 and standard deviation σ83 distributions for the time interval of the
1/83 prescaled RF signal. The red curves show the fitted Gaussian functions.
where αp = 0.0486 stands for the momentum compaction factor, fs = 53 kHz denotes the synchrotron
frequency, and σE /E = 6.28 × 10−4 is equilibrium energy spread [8]. The obtained value of σRF =93.7 ± 0.4 ps is consistent with the expected bunch length of 91.7 ps.

§ 4. Summary

The performance of the developed QTC discriminator has been investigated measuring the time

resolution of the 30-mm-thick plastic scintillator in response to the 707 MeV/c electron beam at ELPH.
The timings are determined by applying pulse-height time-walk correction. The time resolutions agree
well between when we used the correction functions as a function of the charge Qi and when we usedthose as a function of the QTC output width Wi . This suggests that the developed QTC discriminatorworks well for applying the pulse-height time-walk correction in the timing measurement. The bunch
length including the timing fluctuation in the Booster STorage ring is found to be 93.7 ± 0.4 ps. It isdifficult to use the RF signal as a start timing of the time of flight measurement in the present condition.

Acknowledgments
The authors would like to thank the ELPH accelerator staff for providing the stable primary electron beam. They deeply appreciate Y. Takeda and T. Takeda (Fuji Diamond International Co. Ltd.) for
their cooperation of the development and manufacture of the QTC discriminator modules. This work was
supported in part by Grants-in-Aid for Scientific Research (A) (24244022), and for Scientific Research(C) (26400287).

References[1]

T. Ishikawa: ELPH Annual Report 2014, Tohoku University, 113 (2015).

[2]

T. Ishikawa et al.: Research Report of LNS, Tohoku University, 40, 6 (2007).

30
[3]

T. Ishikawa et al.: Nuclear Instruments and Methods in Physics Research Section A 694, 348(2012).

[4]

T. Ishikawa et al.: Nuclear Instruments and Methods in Physics Research Section A 811, 124(2016).

[5]

I. Nagasawa and T. Ishikawa: Internal GeV-γ Analysis Note HD No. 380C, (2015).

[6]

T. Ishikawa: Internal GeV-γ Analysis Note HD No. 379C, (2015).

[7]

F. Hinode et al.: Proceedings of 11th International Conference on Synchrotron Radiation Instrumentation (SRI2012), Journal of Physics: Conference Series 425 (2013) 072011.

[8]

F. Hinode and T. Muto: private communication.

ELPH Annual Report, Tohoku University (2015)31(ELPH Experiment : #2809)

Development of a compact photon-beam profile monitor
S. Kido1 , T. Ishikawa1 , Y. Honda1 , H. Kanda2 , Y. Matsumura1 , M. Miyabe1 ,I. Nagasawa1 , H. Shimizu1 , and Y. Tsuchikawa1
1

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

Department of Physics, Tohoku University, Sendai 980-8578, Japan§ 1. Introduction

We have been conducting the meson photoproduction experiments for baryon spectroscopy at the

Research Center for Electron Photon Science (ELPH), Tohoku University [1]. The energy-tagged photon
beams are used; an internal radiator produces a bremsstrahlung photon from the circulating electrons
in a synchrotron called Booster STorage (BST) ring [2], and its energy is determined by measuring thecorresponding electron with a tagging counter [3]. A photon beam-profile monitor is one of the importantdevices to adjust accelerator parameters.
We have developed several versions of photon beam-profile monitors at ELPH [4–6]. The fourth
generation monitor can measure the intensity map with a dead time of 35 ns for the high-intensity
photon beams corresponding to the circulating electron current of 20 mA in the BST ring. It can measure
the (x, y) position by a 3 mm step, and it is enough resolving power for the photon beams since theirwidths are approximately 8 mm at the circulating electron energy of 1.3 GeV. We have satisfied theperformance of the fourth generation monitor.
All the monitors constructed take a large volume for their readout systems:
1. detector itself measures a size of approximately 500 mm (W)×500 mm (H)×300 mm (T),
2. coaxial cables between the detector in the experimetal hall and the discriminator modules in the
counting room,
3. discriminator modules,
4. an FPGA based logic module, and5. high voltage (HV) supplier to operate photomultiplier tubes.
It is difficult to change the locations for measuring the photon beam-profile. Thus, we have started todevelop a new monitor which can be used at different location in our facility and also in other facilities
easily.
We have required the following conditions for the development of the new monitor:
1. detector itself is small,
2. cirucuit for creating an intensity map is implemented in a board and directly connected to thedetector, and3. HV supplier is included in the circuit.

32
And all the elements for the monitor except for a personal computer display an intensity map are planned
to be placed in a box.

§ 2. Response of a metal-packaged PMT to the photon

So far, we have employed two layers of scintillating fiber (SciFi) hodoscopes for a tracker system.

Each layer has 16 SciFi, and each of which measures a cross section of 3 × 3 mm2 . To determine the two-

dimensional position, two layers are required in this manner. Thus, we consider a multi-anode metalpackaged photo-multiplier tube (PMT) as a tracker system. For example, a PMT, Hamamatsu Photonics
H9500, is a candidate, which has 16 × 16 anodes and measures an effective area of approximately 50 ×
50 mm2 . We have tested metal-packaged PMTs by using photon beams and positron beams at ELPH [7].

At first, the signal of a 4 × 4 multi-anode PMT, Hamamatsu Photonics H6568, in response to the photon

beam is investigated by using a digital phosphor oscilloscope, Tektronics DPO-4104. Fig. 1 shows the
waveform of the output signal of the H6568 PMT in response to the photon beam. The signals have apulse height of 500–700 mV apparently, while the pulse height corresponding to the dark current is lessthan 100 mV in the same condition.

dark current
500~700 mV~100 mV

Fig.1. Waveform of the output signal of the H6568 PMT in response to the photon beam. The
signals have a pulse height of 500–700 mV. The similar pulse-height is observed in other
anodes. The pulse height corresponding to the dark current is less than 100 mV.
We have investigated the output signals of metal-packaged PMTs in response to the high energy
positron beam. In this study, a single-anode metal-packaged PMT, Hamamatsu Photonics R8900U isused. Fig. 2 shows the experimental setup for investigating the response of a R8900U PMT for the highenergy positron beams. Two layers of SciFi hodoscopes, which is the same as the tracker system forthe previous photon beam-profile monitor, determine the incident position, and make a trigger for dataacquisition. The SciFis are connected to H6558 PMTs. The penetration of the positron beam is confirmedwith a PS with an area of 70 × 70 mm2 with a thickness of 1 mm, which is the same as a trigger PS in

the previous photon beam-profile monitor. The PS is connected to a 2-inch PMT, Hamamatsu Photonics
H7195. The CAMAC-based data acquisition system is used. The energies of the output signals are33
measured with ADC modules, LeCroy 2249W and REPIC RPC-022, and the timings are measured with
TDC modules, REPIC RPC-060.

positron beam
R8900U

H6568

H7195

Fig.2. Experimental setup for investigating the response of a R8900U PMT for the high energy
positron beams. The incident position is determined with two layers of SciFi hodoscopes,
and the penetration of the positron beam is confirmed with a PS with an area of 70 ×
70 mm2 with a thickness of 1 mm. The SciFis are connected to H6558 PMTs, and the PS
is connected to a 2-inch PMT, Hamamatsu Photonics H7195.
The efficiency of the R8900U PMT in response to the positron beam is estimated from the taken
data. The positron beams are injected from the front, rear, and side faces. Fig, 3 shows the efficiency
maps of the R8900U PMT in response to the positron beam. The efficiency is approximately 100% in theactive area (23.5 × 23.5mm2 )of the R8900U PMT when the positron beam is injected from the front andrear faces. When the positron beam is injected from the side rear face, an enhancement of the efficiency
is observed in two lines corresponding to the PMT window and first dynode. The obtained efficiency
maps suggest that the secondary electrons produced at the PMT window and first dynode generate theoutput signals. The gain is thought to be higher for events in which the secondary electrons are produced
at the PMT window, and the number of the seed electrons are larger than that corresponding to the darkcurrent.
We have also investigated the output signals with several thicknesses of PSs connected to theR8900U in response to the positron beam. The thicknesses of PSs are 0, 0.5 and 3.0 mm, where 0means that no PS is connected to the PMT. Fig. 4 shows the charge integration distributions for three
thicknesses together with the distribution for the dark current. Each distribution is fitted with a
Moyal function [8] to get the centroid (µ) and the width (σ) of the peak. The parameters (µ, σ) are(6.3 ± 0.7, 1.5 ± 0.1), (45.5 ± 0.3, 6.6 ± 0.4), and (389.2 ± 1.2, 34.2 ± 2.1) pC for 0, 0.5 and 3.0-mm thick-nesses. Some dark current events have the charge integration larger than 2 pC although it is basically

34

10

0.6

-5

0.5
0.4

-10
-6

0
x (mm)

6

12

5
y (mm)y (mm)

0

10

0.25

0.9

0.8
0.7

from the side face

1

10

0.9

5

-12

from the rear face

1

0.8
0
0.7

y (mm)

from the front face

5

0.2

0

0.15
0.1

-5

-5
0.6
-10
-12

-6

0
x (mm)

6

12

0.5

0.05
-10
-12

0
-6

0
x (mm)

6

12

Fig.3. Efficiency maps of the R8900U PMT in response to the positron beam. The left, central,and right panels shows those the positron beams are injected from the front, read, andside faces, respectively.
much smaller than 2 pC. The separation power is not so high for a single positron penetration. The
separation power becomes much better for a photon detection because we detect two minimum ionizing
particles namely an electron and positron pair.

Fig.4. Charge integration distributions for 0, 0.5, and 3.0 thicknesses together with the distribution for the dark current. The left three panels show those for 3.0, 0.5, 0 mm thicknesses
from the left side, and the right panel shows the distribution for the dark current.

§ 3. Test of a prototype beam-profile monitor

We have constructed a prototype beam-profile monitor consisting of a charge PS, 4 × 4 multi-anode

H6568 PMT, and manufactured print-circuit-board including a Spartan-6 FPGA chip [9], 16 leading-edge

discriminators, 2 constant-fraction discriminators, and a level converter for the RS-232C communication.
The data acquisition with the board for the profile monitor is programmed in VHDL using an integrated
development environment Xilinx ISE WebPACK Ver. 14.7 [10]. Fig, 5 shows the prototype print-circuitboard for the profile monitor and typical profile measure with it. The position is determined by the
responding anodes in the H6568 PMT, and the charged particles produced upstream are rejected with35
the charge PS. The photon intensity in a unit area is measured for several anodes without using trigger
PS, and the measured intensity is scattered from 0.5 to 2.0 even in the same position. This is because
the signals of an anode includes those for the dark current and the measured intensity is affected by thedark current rate. The details of the analysis are described elsewhere [11].

Fig.5. Prototype print-circuit-board for the profile monitor and typical profile measure with it.
The H6568 PMT is used as a multi-anode PMT.

§ 4. Summary

We have been developing a new compact photon beam-profile monitor at ELPH. The positions ofphotons producing electron-positron pairs at the converter are determined with a multi-anode PMT. The
secondary electrons produced by the electron-positron pairs are found to generate enough large signals
in the PMT. The detector and circuit will be contained in a box, and we can use it anywhere we want.

Acknowledgments
The authors wish to thank the ELPH accelerator staff for providing the primary electron beamin the stable condition. This work was supported in part by Grants-in-Aid for Scientific Research (A)(24244022), and for Scientific Research (C) (26400287).

References[1]

T. Ishikawa et al.: Proceedings of the 10th International Workshop on the Physics of Excited Nucleons (NSTAR2015), JPS Conference Proceedings 10, 031001 (2016);
T. Ishikawa et al.: Proceedings of the XV International Conference on Hadron SpectroscopyHadron 2013, PoS (Hadron 2013) 095;
T. Ishikawa et al.: Proceedings of the 20th International IUPAP Conference on Few-Body Problemsin Physics, Few Body Systems 54, 1047 (2013);
T. Ishikawa et al.: Research Report of LNS, Tohoku University, 42&43, 1 (2011).

36
[2]

F. Hinode et al.: Proceedings of 2005 Particle Accelerator Conference, 2458 (2005);
F. Hinode et al.: Proceedings of 11th International Conference on Synchrotron Radiation Instrumentation (SRI2012), Journal of Physics: Conference Series 425, 072011 (2013).

[3]

T. Ishikawa et al.: Nuclear Instruments and Methods in Physics Research Section A 622, 1 (2010).

[4]

M. Nanao, T. Ishikawa, and H. Shimizu, Research Report of LNS, Tohoku University, 36, 56 (2003).

[5]

H. Fujimura et al.: Research Report of LNS, Tohoku University, 42&43, 56 (2011).

[6]

T. Ishikawa et al.: Nuclear Instruments and Methods in Physics Research Section A 811, 124(2016).

[7]

T. Ishikawa et al.: Nuclear Instruments and Methods in Physics Research Section A 694, 348(2012).

[8]

J.E. Moyal, Philosophical Magazine 46 (1955) 263;
M.D. Marucho, C.A. Garcia Canal, H. Fanchiotti, International Journal of Modern Physics C 17
(2006) 1461.

[9]

Spartan-6 website: ⟨http://www.xilinx.com/products/silicon-devices/fpga/spartan-6.html⟩.

[10] ISE

WebPACK

webpack.html⟩.

website:⟨http://www.xilinx.com/products/design-tools/ise-design-suite/ise-[11] S. Kido, Mater thesis, Tohoku University, 2016.

ELPH Annual Report, Tohoku University (2015)37(ELPH Experiment : #2812, #2813)

Development of the photon tagger for the NKS2 experiment
H. Kanda1 , K. Honda1 , T. Ishikawa2 , M. Kaneta1 , K. Maeda1 , M. Miyabe2 ,Y. Muroi1 , S. Nagao1 , S. N. Nakamura1 , A. Ninomiya1 , T. Nishizawa1 ,K. Ozeki1 , T. Sasaki1 , A. O. Tokiyasu2 , and Y. Toyama1
12Graduate School of Science, Tohoku University, Sendai 980-8578, Japan

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

We have been developing an internal photon tagger for the NKS2 experiment. It is composed of 40
counter units based on MPPCs. Assembling of the counter units and their arrangement on the counterbase frame were completed. Their commissioning and test experiments with the electron beam was
performed. After the completion of the basic development, we measured the eta meson photoproduction
on the proton for the energy calibration of the tagger using the threshold energy of the eta meson. The
analysis of the data is underway. We report the current status of the development of the photon tagger
and the analysis for the energy calibration.
We have been developing an electron detector of the internal photon tagger as a recovery andan upgrade of the STB-Tagger [1] which was damaged by the Tohoku Earthquake on 11 March 2011.
Bremsstrahlung photon beams are generated at a target called as the radiator inserted in the electron
beam line of the electron booster and storage ring (BST ring) [2]. The movable target system is locatedat 300 mm upstream of the fourth bending magnet (BM4) of the accelerator. The electron detector isplaced in the space between the pole and the yoke of BM4 and detects momentum analyzed electrons
after the bremsstrahlung and thus define timing and energy of radiated photons. The newly developed
electron detector consists of scintillation counters based on Multi-Pixel Photon Counters (MPPCs) supplied by Hamamatsu Photonics K. K. The read-out system for the timing counters (TagBs) consists ofordinary leading edge discriminators. A differential amplifier circuit was developed [3, 4], to reduce thepile-up of the MPPC signal with long tail and the dark counts of the parallel-connected MPPC array.
The other read-out system for the position counters (TagFs) is EASIROC [5] based electronics [6] aiming
at an easy operation of multi-channel counters. We designed an electron detector of the photon tagger
composed of counter units each of which has four TagFs and one TagB. By a coincidence of a TagB andone of four TagFs belonging to one counter unit, a trajectory of an electron can be selected to reduce anelectromagnetic background from electrons, positrons or gamma rays coming from other sources.
The alignment of the counter unit was determined using a GEANT4 based Monte Carlo simulation
with a magnetic field of the BM4. Trajectories of electrons after the bremsstrahlung of 1.31 GeV electrons
on the radiator was calculated and the injection angles, positions and energy deposits of the electrons on
the scintillators of the counter units were simulated. We aligned the counter units with angles parallel

38
to the electron trajectories and positions avoiding the interference between counter units. The calculated
positions and some samples of the trajectories are shown in the magnified view of Fig. 1. The range ofthe tagged photon energy was estimated to be 0.78 to 1.27 GeV for the 1.3 GeV operation of the BST
ring.
Radiator
Bending magnet

STB vacuum chamber

Bending Magnet (BM4)Collimator(10 mm diameter)

Counter units

Sweep magnet
Concrete shield
Veto counter

Ee= 50 MeV

Ee= 100 MeV

tro
ns
rah
rem
stb

Ee= 400 MeV
Ee= 500 MeV

sst

Ee= 300 MeV

Po

Lead glass
Cherenkov
counterge

B

Ee= 200 MeV

ST

High Speed BPM

lun

va
c

lec

uu

m

ch

Va
cu
u

m

am
be

du

r

ct

Dipole magnet

Fig.1. Schematic diagram of the setup along the photon beam line and the magnified view of
the tagger.

The case for the electron detector was designed to have the following three functions: (f1) to alignand fix the counter units on it; (f2) to hold connector changing circuit boards, cables for signals, bias
power, and preamplifier power; and (f3) align the base itself to the magnet. Its shape had to fulfill thefollowing requirements: (r1) compactness for the insertion through the limited space between the BM4
and a quadrapole magnet (QC2) just upstream of the BM4; (r2) sufficient length to fix all the counter
units with the length of 1 m; and (r3) avoidance of the matters which affect the magnetic field of theBM4. The final design is shown in Fig. 2. We fixed a rail with a groove on the lower yoke of BM4 andset a pin which fits the groove to fix its motion along the rail for (f3). The frame itself has two levels ofbase plates. Top plate is used for (f1) and the bottom plate is used for (f2). The cables from the counter
units to the connector changing boards are placed through small holes on the top plate. They are fixedwith black silicone RTV to be light-tight. The frame was separated in two parts with lengths of 0.397
m for the upstream and 0.73 m for the downstream to fulfill two requirements (r1) and (r2) at the sametime. They were connected with a detachable pin to allow a rotation around it. After the insertion in the
BM4, the downstream part was puled to the upstream part with a wire for the tight connection between
two parts. The frame was fixed to the BM4 with some jigs fixed on the side yoke. The plates and spacers
between top and bottom plates were made of black MC nylon and all the matters of screws and pins wereselected with small magnetism such as brass, titan, and thermal treated SUS304 for fulfilment of (r3).
We assembled all the counter units and mounted them on the detector case (Fig. 3).

39

Dark box

Fig.2. Schematic design of the detector case of the tagger.

Fig.3. Photograph of the detector case of the tagger with all the counter units mounted on it.

After the construction and the installation of the electron detector to the BM4, we tested its tagging
efficiency and relative energy for each tagging counter using a lead glass Cherenkov detector (LG). Its
experimental setup is shown in Fig. 1. The LG was placed at the most downstream part of the beamline and used for the measurement of the energy of photons with sufficient efficiency. The descriptionof the LG is found elsewhere [7]. The ADC spectrum of the LG gated on the hit of each tagging counter
was fitted with a Gaussian function to find the central value. These central values were normalized to
the value for TagB1 and shown as a function of the TagB segment number in Fig. 4. There were slight40
discrepancy from the simulation. The data and simulation are currently being checked.

Relative photon Energy

1.05

Data

1

Simulation

0.95
0.9

0.85
0.8
0.75
0.7
0.65
0.6
0.55
0

5

10

15

20

25

30

35
40
TagB segment

Tagging efficiency

Fig.4. Relative tagged photon energy normalized to the photon energy corresponding to TagB1
shown as a function of the TagB segment number for the 1.3 GeV operation of the BST
ring. Solid circles denote the measured data and open circles denote results of the Monte
Carlo simulation. Energies for TagB39 and 40 were measured several times as the reference of the systematic error.

1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0

5

10

15

20

25

30

35
40
TagB segment

Fig.5. Tagging efficiency as a function of the TagB segment number for the 1.3 GeV operationof the BST ring. Efficiencies for TagB39 and 40 were measured several times as thereference of the systematic error.

The tagging efficiency ϵi for the i-th tagging counter was defined asϵi =Niphoton

Nitag (ON ) − Nitag (OF F )(1)

where Niphoton is the number of photons detected with the LG in coincidence with the i-th tagging
counter; Nitag (ON ), the number of the hits on the i-th tagging counter with the radiator interested
to the electron beam; and Nitag (OF F ), the number of the hits on the i-th tagging counter without inserting the radiator. Number of photons were obtained by setting gates on the ADC values of the LG
because the ADC spectrum had the broad tail in the lower energy region due to the secondary particles

41
from a supporting rod and the wall of the vacuum chamber of the accelerator in the BM4. The tagging
efficiency measured for the 1.3 GeV operation of the BST ring is shown in Fig. 5. It was sufficient for theexperiment. We selected the single hit on the TagB in these analyses. The detailed analysis of TagBs
and TagFs for the selection of the trajectory of the post-bremsstrahlung electrons is underway.
We performed an experiment for the calibration of the photon energy using η photoproduction on
the proton taking advantage of the steep rise of the cross section from the threshold (0.7078 GeV). The
electron energy of the BST was set as 0.900 GeV. The energy of the tagged photon beams was estimatedto range from 0.533 GeV to 0.868 GeV with the simulation. TagB26 was estimated to correspond to thethreshold energy of η photoproduction on the proton. The main decay modes of η are neutral modes
such as η → 2γ(39.41%) and η → 3π 0 (32.68%). We detected the recoil proton with the NKS2 to identify

the η with the missing mass. Detailed setup of the detectors of the NKS2 is shown in Fig. 6. The
inner hodoscope (IH) of the NKS2 does not cover the most forward angular region in order to reduce thematter along the beam line. For covering the proton emitted in the very forward angle at the threshold,we placed a counter with a 2.6 mm-thick scintillator (TC). It was treated as another segment of the IH in
the analysis. The largest emission angle of the proton in the laboratory system was 31 degrees. The 4th
segment of the IH covers the horizontal angle from 18 to 30 degrees. We set a multiplicity trigger only
including the TC and the 1st to the 4th segments of the IH. The segments of the outer hodoscope (OH)required for the trigger were also limited to cover the emitted proton. The other segments of the IH andthe OH were used for the detection of charged pions in the offline analysis. The request of the detectionof a proton and no other charged particles was expected to efficiently reduce the largest backgroundfrom γp → π + π − p. The momentum of the recoil proton ranged from 0.2 GeV/c to 0.8 GeV/c which were
sufficiently in the momentum acceptance of the NKS2 for the proton.
OHVL OHVR
OHHL

8 7 654

3 21 12 34

5

6 7 8

OHHR

PMT

IH
TC
beam axis
IHL2
IHL3
IHL4

OHVR

OHVL

γ beam
Fig.6. Setup of the detectors of the NKS2.

30 deg}γ beamScintillator

PMT

42
Total numbers of the tagger hits were 1.3 × 1011 for the hydrogen target runs, and 5.3 × 1010

for the empty target runs in the beam time. The empty target runs were used for the subtractionof the background emerging from the non-target region because we could not define the target region
from the vertex reconstructed from the single proton measured in the forward angle. The numbers ofrecorded events were 1.4 × 108 for the hydrogen target runs. By the simple estimation consideringthe η photoproduction cross section calculated with eta-MAID [8], a target density, a duty factor of theaccelerator and efficiencies of the data acquisition, the tracking and the tagger, the estimated yield of η
was estimated to be 80 for single TagB at the threshold region.

As the first step analysis, we only used the information of the hodoscopes. The segments of the IH
used in the analysis were limited to TC and IHL2. The segments of the OH used were OHVL1, OHVL2,
OHVL3, and OHVL4, considering the bending angle of the proton passing through both of the TC andthe IHL2. The first ADC peak of the hodoscopes were assumed to correspond to the energy deposit of aminimum ionizing particle and used for the calibration of the energy deposit. The timing of the counterswere calibrated using minimum ionizing particles and assuming their flight length as 1 m from the IH
to the OH and their velocity as β = 1. Correlation between the velocity of the particle and its energy
deposit of the OH was used for the particle identification (PID). The lowest momentum of the charged
pion measured with the NKS2 was 0.1 GeV/c and its velocity was β = 0.58. The highest momentum of
the proton in the η photoproduction in this energy region was 0.8 GeV/c and is velocity was β = 0.65.
The graphical cut condition for the proton was defined as shown in Fig. 7 by considering the resolutionof the velocity and energy deposit and for reducing distribution in the small energy deposit region.

Fig.7. Correlation plot of dE/dx on OHVL counter vs. beta for the proton selection. Distribution
for particles identified as the proton is shown in the right panel

The momentum distributions of the selected proton for the hydrogen target runs and the empty
target runs normalized for the number of accepted trigger are shown in Fig. 8. Enhancement of the
proton yield in the momentum range of 0.3 GeV/c to 0.6 GeV/c can be seen. The momentum corresponds
to the recoil proton in the η photoproduction from its threshold to the photon energy of 0.74 GeV. For
better selection of the proton and the kinematical selection with the missing mass, absolute momentum
and the direction at the target region is indispensable. The calibration of the MWDCs and analysis withthe tracking information is underway.

Counts

43
8000
7000
6000
5000
4000
3000
2000
1000
0

0

0.2 0.4 0.6 0.8 1.2 1.4 1.6
Momentum (GeV/c)

Fig.8. Momentum distribution of the proton for the hydrogen target runs (red curve) and for theempty target runs (blue curve).

In summary, the development of a new tagger for the NKS2 was coming to its final stage. The
tagging efficiency and the relative photon energy were measured using the LG. The tagging efficiency
was sufficiently high for the performance of the experiment for the 1.3 GeV operation of the BST ring.
The discrepancy of the photon energy from the simulation is currently being checked. In the analysis ofthe η photoproduction on the proton for the energy calibration, a sign of the η production were seen in
the momentum distribution of the proton. Detailed data analysis in underway.
We plan to perform the commissioning of the NKS2 with the Λ photoproduction on the deuteron in
the photon energy region from 1 to 1.27 GeV in June 2016. It partly overlaps the energy range of ourprevious measurement of Λ photoproduction from 0.78 to 1.08 GeV [9] but exceeds it by 0.2 GeV. The
obtained data will be used for checking of the consistency with the previous data but it will be a newdata taking full advantage of the upgrade of the BST and the new tagger.

Acknowledgment
We would like to thank the administration and technical staff in ELPH and the faculty of science.
This program was partly supported by Core-to-core program (21002), strategic young researcher overseas visits program for accelerating brain circulation (R2201), and KAKENHI Grant Number 23540334
by JSPS.

References[1]

H. Yamazaki et al.: Nucl. Instr. and Meth. in Phys. Res. A 536 (2005) 70.

[2]

F. Hinode et al.: Proceedings of 11th International Conference on Synchrotron Radiation Instrumentation (SRI2012), Journal of Physics: Conference Series 425 (2013) 072011.

[3]

T. Nishizawa et al.: IEEE trans. Nucl. Sci. 61 (2014) 1278.

[4]

H. Kanda et al.: Conference Record, Nuclear Science Symposium and Medical Imaging Conference(NSS/MIC), 2013 IEEE.

[5]

S. Callier et al.: Phys. Procedia 37 (2012) 1569.

[6]

R. Honda et al.: PoS PhotoDet2012 (2012) 031.

44
[7]

H. Kanda et al.: Research Report of Laboratory of Nuclear Science, Tohoku University 44 (2011).

[8]

W.-T. Chiang, S.-N. Yang, L. Tiator, D. Drechsel: Nucl. Phys. A 700 (2002) 429.

[9]

B. Beckford et al.: Prog. Theor. Exp. Phys. 2016 (2016) 063D01.

ELPH Annual Report, Tohoku University (2015)45(ELPH Experiment : #2813, #2828)

新光子標識化装置 STB TaggerIIs で使用する MWDC の性能評価
佐々木未来 1 , 本多 佑記 2 , 井上陽介 2 , 石川貴嗣 2 , 岩佐美和 1 , 叶内萌香 1∗ , 木戸聡 2 ,松村裕二 2 , 三浦大輔 1 , 宮部学 2 , 村松憲仁 2 , 櫻井輝昴 1 , 笹川瑞樹 2 , 盛道太郎 1 ,関悠登 1 , 清水肇 2 , 田島靖久 1 , 高橋季己 1 , 時安敦史 2 , 土川雄介 2† , 吉田浩司 11 山形大学理学部(990-8560 山形県山形市 小白川町一丁目 4-12)

2 東北大学電子光理学研究センター（982-0826 仙台市太白区三神峯 1-2-1）

Performance test of MWDC for a photon tagging system
STB TaggerIIs
M. Sasaki1 , Y. Honda2 , Y. Inoue2 , T. Ishikawa2 , M. Iwasa1 , H. Kanauchi1∗ ,S. Kido2 , Y. Matsumura2 , D. Miura1 , M. Miyabe2 , N. Muramatsu2 ,T. Sakurai1 , M. Sasagawa2 , M. Sei1 , Y. Seki1 , H. Shimizu2 , Y. Tajima1 ,T. Takahashi1 , A.O. Tokiyasu2 , Y. Tsuchikawa2† , and H.Y. Yoshida112Department of Physics, Yamagata University, Yamagata 990-8560

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

A new photon tagging system, which is STB TaggerIIs, has been developed for the FOREST experiment. In order to measure the photon energy more precisely, the STB TaggerIIs consists of the multi wire
drift chamber (MWDC) and the hodoscope. A new MWDC is adopted as an electron tagging device todetermine the trajectories of the recoil electrons from the target. And it was tested using positron beamat ELPH in November 2015. The measured efficiency was 99 ％ or higher and the position resolution 76µm.

§ 1 . 研究背景
現在 ELPH では、FOREST 実験のための新しい標識化装置 STB TaggerIIs を開発している。FOREST
実験で使用する光子ビームは、BST リングの周回電子へカーボンファイバーを差し込むことによって起こる
制動放射から作られている。制動放射により発生した光子のエネルギーは連続スペクトルを持つため、個々の光子ビームを特定し、エネルギーを決定する必要がある。その為の装置が標識化装置である。第 1 図に標
識化装置の概要を示す。制動放射により光子を放出した反跳電子はエネルギーを失い、加速器の偏向電磁石
により周回軌道よりも内側に曲げられる。標識化装置はこの反跳電子の軌道上に設置され反跳電子を検出する。反跳電子の検出は反跳電子と対をなす光子ビームを特定することができ、これを標識化と呼ぶ。反跳電子の電子のエネルギー Ee′ を測定することで、光子ビームのエネルギーを Eγ も求めることができ、周回電∗

Present address : Department of Physics, Tohoku University, Sendai, 980-8578†

Present address : Department of Physics, Nagoya University, Nagoya, 464-8602

46

子のエネルギーを Ee とすると、

Eγ = Ee − Ee′

(1)

となる。

TaggerⅡse’e
Ti windowγ

radiator

第1図

光子標識化概念図

反跳電子は周回する加速器のビームパイプから 50 µm 厚のチタン製のウィンドウを通過して STB TaggerI

Is へ入射する。この際に、高エネルギー反跳電子はウィンドウのフレームにあたり低エネルギーの二次粒子を発生させる。現行の標識化装置である STB TaggerII では、この二次粒子がバッググラウンドになることがわかっており、新しく製作する STB TaggerIIs には反跳電子と二次粒子を区別するための 5◦ の角度分解
能と、周回ビームのバンチを区別するための 200 ps 以下の時間分解能が要求される。これらの要求を満たすため、高角度分解能を持つ MWDC と、高い時間分解能を持つホドスコープの二つの機器から構成される。本レポートでは製作した STB TaggerIIs の MWDC の性能評価試験を行った。

1.1 MWDCSTB TaggerIIs で使用する MWDC について述べる。MWDC の仕様を第 1.1 表、写真を第??図に示す。
フレームは設置場所である偏向電磁石の内壁に合わせた円弧上になっている。第 2 図に MWDC のセル構造を示す。赤い点はセンスワイヤー、青い点はポテンシャルワイヤーそして緑の点はスイープワイヤーの配置を表す。一つのセルはセンスワイヤーを中心に六角形にポテンシャルワイヤーが配置されている。センス
ワイヤーの間隔は 6 mm で、X プレーンのみの 3 層構造である。
第 1 表 MWDC 仕様
フレーム寸法1000 mm × 136 mm
フレーム材質
アルミニウム
ワイヤー長
30 mm
ワイヤープレーン
X のみ
層数
3
チャンネル数448
ワイヤー材質金メッキタングステン
ポテンシャルワイヤー、スイープワイヤー径
50 µm
センスワイヤー径
20 µm

47

sweep wire

sence wirepotential wire

6mm

第2図

MWDC のセル配置。赤がセンスワイヤー、青がポテンシャルワイヤー、緑がスイープワ
イヤーを表す。

MWDC の信号の読み出しには林栄精器と KEK で開発された読み出しボード 64ch RAINER [1]を小型化した 32ch RAINER を使用する。RAINER はボード上で入力信号の ADC、TDC データの取得が可能
で、処理されたデータは SiTCP を使って、イーサネット経由で PC へ読み出すことができる。第 3 図に示したように、RAINER の大きさは 120 mm × 100 mm で、MWDC に取り付けて偏向電磁石の内部 ( 120mm × 350 mm) に挿入できるサイズに収めた。性能を第 2 表に示す。

第3図

32ch RAINER§ 2 . 性能評価実験
第 4 図にビームテストのセットアップを示す。T0、T1、T2 はトリガーカウンターで、T0 は 50 mm ×

50 mm × 10 mm、T1、T2 は 30 mm × 30 mm × 5 mm のプラスチックシンチレータで構成されている。また、T0 は両側、T1、T2 は片側に PMT を取り付けている。陽電子ビームは 100∼900 MeV のエネ
ルギーを使用した。また、入射角度に対する応答を測定するため、チェンバーは回転ステージに乗せ、回転させることによってビームを入射角度 0、30、45、60◦ で入射させた。今回の実験では、32ch RAINER
は２枚使用し、中心部分の 64 チャンネルのみのデータを取得した。

48

第 2表
処理信号数

RAINER 仕様 [2]、[3]32 チャンネル
アナログゲイン -1.1 V/pC
Amp Shaped Discrimenater
デジタルゲイン -15 V/pC
タイムウォーク < 500 ps
解像度 10 bit
ADC
取り込み周期 32 ns
サンプリング周波数 31.25 MHz
TDC
解像度 1 nsec
データバッファ8 µs リングバッファ

T0 L
beam
T1

T2

T0 R

MWDC
第4図

Set up of the beam test.

2.1 プラトーカーブ
MWDC に印加する電圧は、以下の式で定義した第 n 層の検出効率が 99 ％以上になるように決定した。
eﬃciency =3 層すべてが hit したイベント数
第 n 層以外の 2 層がヒットしたイベント数(2)

スイープワイヤーにはポテンシャルワイヤーの 90 ％の電圧を印加した。測定した検出効率と印加電圧の相関図を, 図 5 に示す。２層目の検出効率が１、３層目に比べて低いのはポテンシャルワイヤーとスイープワ
イヤーの電圧比が最適化されていないためと考えられる。印加電圧 2200 V 以上で検出効率 99 ％以上を達成できることがわかるが、2200 V では放電の兆候が見られたため、印加電圧はポテンシャルワイヤー 2150

V、スイープワイヤー 1950 V に決定した。[4]2.2 X-T 分布
垂直入射のデータから得られた時間の分布を第 6 図に示す。このような、TDC 分布からビームの通過位′置を再構築する。各層のビームの通過位置 Xn は、センスワイヤーの位置 X0 、ガス中の電子のドリフト速
度 vd と TDC 分布より得られるドリフト時間 tn より,

Xn′ = vd × tn + X0n(3)efficiency

49

1

0.8

0.6

0.4

0.2

0

第5図

1700

1800

1900

2000

2100

2200

2300

2400

HV[V]

各層ごとのプラトーカーブのプロット。赤が１層目、緑が２層目、青が 3 層目の検出効率を表す。
′

で計算できる。式より得られた各層の Xn とセンスワイヤーの Z 位置からビームの飛跡が直線であることを仮定してフィッティングし、新たな各層のビームの通過位置を Xn を算出する。フィッテイングには図 7 に示すような入射座標を用いて行った。垂直入射を仮定しているので陽電子が通過した Z 座標にはセンスワ
イヤーの Z 座標と同じ値を用いた。

102

10

1

10−1
0

20

第6図

チェンバー１チャンネルの TDC 分布

40

60

80

′

100

ns

式 3 より求めた Xn と, フィッティングにより求めた Xn の残差分布を第 9 図に示す。この結果, 得られた位置分解能は 76 µm となった [4]。

50

5

4

3

フィッティングに用いた入射位置の座標

TX layer 0
１層目
Mean xMean yStd Dev x
Std Dev y
χ2 / ndf
p0
p1

22

28.88
1.547
16.4
0.89452.298e+04 / 653−0.03527 ± 0.01143
0.05387 ± 0.0003397

20
18

X-X’ mm

X-X’ mm

第7図

TX layer 1
２層目

5

Mean xMean y

4

16
14

ary

3

12
2
10
8

1

n
i
m

6
4

0

2

X-X’ mm

−1
−10

5

4

3

0

10

20

30

40

TX layer 2
３層目
Mean xMean yStd Dev x
Std Dev y
χ2 / ndf
p0
p1

28.29
1.513
16.4
0.892
2.393e+04 / 668−0.03233 ± 0.01135
0.05368 ± 0.0003427

2

1

i
l
e
r

50

60

70
80
time nsec

p

0

2

1

0

−1
−10

0

10

20

30

40

29.94
1.533
Std Dev x
15.82
Std Dev y
0.8844χ2 / ndf
9.958e+04 / 974
p03.136 ± 0.02058
p1−0.05268 ± 0.0005999

14
12
10
8
6
4
2

50

60

70
80
time nsec

0

22
20
18
16
14
12
10
8
6
4

0

2
−1
−10

第8図

0

10

20

30

40

50

60

70
80
time nsec

0

X-T プロット。図中の赤線はこの分布へ直線でフィッティングした結果である。

§3 . ま と め
ELPH では FOREST 実験のための新しい標識化装置 STB TaggerIIs を開発している。標識化装置は飛跡検出のための MWDC と、時間測定のためのプラスチックシンチレータから構成されている。本研究では 100 〜 900 MeV/c の陽電子ビームを用いて MWDC の性能評価試験を行った。その結果 99 ％以上の検出効率と、76 µm の位置分解能が得られた。今後、斜め入射の実験データを用いて角度分解能を見積もる予定である。

51

第9図

′

式 3 より求めた Xn とフィッティングにより求めた Xn との残差分布

参
[1]

考

文

献

Readout electronics for the central drift chamber of the Belle II detector, Uchida, T., Ikeno, M.,
Iwasaki, Y., Saito, M., Shimazaki, S., Tanaka, M., Taniguchi, N., Uno, S., 2012 IEEE Nuclear
Science Symposium Conference Record, pp. 694-698.

[2]

林栄精器株式会社 : 64ch READOUT BOARD スタートアップガイド Rev01 3[3]

林栄精器株式会社 : ASD IC 型式 JRK B ASD-CMOS カタログ[4]

佐々木未来 他: GeV-γ ビームラインにおける新光子標識化装置の開発 V、日本物理学会第 71 回年
次大会 (2016)

52

ELPH Annual Report, Tohoku University (2015)(ELPH Experiment : #2815)

Measurement of the electron beam size at the BM5 radiatorin the BST ring
Y. Obara1 , H. Hama2 , F. Hinode2 , T. Ishikawa2 , 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, Tohoku University, Sendai 982-0826, Japan
3
4

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

Institute of Particle and Nuclear Studies (IPNS), High Energy Accelerator Research
Organization (KEK), Tsukuba 305-0801, Japan§ 1. Introduction

Meson photoproduction experiments for baryon spectroscopy have been conducted at the ResearchCenter for Electron Photon Science (ELPH), Tohoku University. In the experiments, we use the energytagged bremsstrahlung photon beams, which are generated by inserting a carbon fiber (radiator) into circulating electrons in a synchrotron called Booster STorage (BST) ring [1]. The BST ring is the upgradedsynchrotron from the STretcher Booster (STB) ring [2], and the maximum energy has been increased
from 1.2 to 1.3 GeV. It is important to measure the properites of the circulating electrons in the BST
ring, which affects the properties of the photon beams. We have measured the electron beam size at theradiator point.
The horizontal beam size σ in a synchrotron is expressed by
√
)2
(
dp
σ = βϵ + η
p(1)

where β denotes one of the Twiss parameters α, β, and γ, η stands for the dispersion, and dp/p is theequibrium momentum spread. The lattice structure of the BST ring gives α, β, γ, η, and dp/p. Misalignment of the elements and poor degree of vaccum in the BST ring also affect these values. To reveal
the properties of the circulating electrons, we have measured the horizontal beam size.

§ 2. Method

The electron beam intensity penetraring the radiator can be determined from the the photon in-tensity as a function of the elapsed time. The bremsstrahlung is generated by inserting a carbon fiber
into the circulating electron beam. Figure 2 shows the schematic view of the radiator and its frame. To
keep the photon intensity constant, this frame is moved by the stepping motor in the normal operation.
An energy of a generated photon is tagged using STB-Tagger-II [3]. It is composed of 116 telescopes of
upstream and downstream scintillating fibers, eight of which are directly connected to a multi-anode53
photomultiplier tube . Each telescope determines the trajectory of a recoil electron and gives its momentum and the corresponding generated photon as shown in Fig. 1. The details of STB-Tagger II are
described elsewhere [3]. When the radiator is fixed at a position of x, a counting rate of a tagging channel
is proportional to the number of circulating electrons passing through the radiator. The counting rate
N (t) as a function of the elapsed time t is given as(2)

N (t) = N0 exp(−α(x)t)

where N0 is the counting rate at the time of t = 0 and α(x) denotes a decay constant at a fixed position of
the radiator. Assuming that the electron beam profile in the BST ring does not depend on the circulating
current, the decay constant α(x) is proportional to a fraction of electrons at a position x. Thus, the center
position and width of the electron beam can be determined from the decay constant α(x) as a function of
the radiator position x. We have determined the horizontal electron beam sizes at the radiator position
for 1.3, 1.0 and 0.8 GeV modes.

Fig.1. Schematic view of STB-Tagger II. The energy of a produced photon is determined measuring its corresponding recoil electron.

Radiator
Position x

Radiator Frame

Carbon Fiber

Fig.2. Schmeatic view of the radiator and its frame. The carbon fiber with a diameter of 11 um
is fixed between two tips of a fork-like frame. The frame can be moved in a horizontal
direction using a stepping motor.

§ 3. Readout

To give the photon intensity as a function of the elapsed time, the number of counts of the taggers

in a definite period of time is measured. We measured a beam size once during the SCISSORS II ex-54
periments. In the previous measurement [4], we have measured counting rates in every 0.1 s (0.5 s)
period for the Ee = 0.9 GeV (Ee = 1.2 GeV) mode. One of the tagging channels was measured usinga CAMAC scaler in one measurement. Photon intensity near center of the beam could not be evaluated owing to counting loss by probleams of signal processing. To obtain the number of counts forseveral tagging channels without counting loss for a long time, we used a scaler circuit implemented ina general-purpose lgoic module called MPLM4X [5], which has a Xilinx Spartan-6 FPGA chip. We placed
electric circuits nearby the tagging counter station in order to decrease the deterioration of the singals
during the propagation. The counting rates of sixteen channels in the taggers were measured in orderto check consistency of obtained center positions and widths of the electron beam. The number of data
points in each side (+x and −x) ranges from 10 to 20 in a 0.1 mm step. We measured the counting rates

in one of the data points for a block RAM implemented in the FPGA of the MPLM4X. The block RAM
has a depth of two minutes.
The scaler implemented in the FPGA was composed of the following functions:
1. MPLM4X DCM2 converts an input clock of 10 MHz to a clock of 200 MHz and distributes othercomponents,
2. EOS RESET outputs a global reset signal until the READY state after power activation,
3. Scaler counts the number of hits of the taggers for 0,1 seconds,
4. Scaler controller controls data which the ’Scaler’ component records,
5. the BRAM component gives a block RAM for describing the number of counts in 120 s, and6. DAQ Controller controls states of the constructed circuit in the measurement and data transmission between a PC using an RS-232C communication.
Figure 3 shows a block diagram of the components of the scaler.

Fig.3. Block diagram of the scaler.

55§ 4. Measurement of the electron beam profile

We have measured counting rates of the taggers after inserting the radiator in modes of Ee = 1.3,

1.0 and 0.8 GeV as shown in Fig. 4. The counting rate decays exponentially and the red lines are fitting
curves expressed as
N (t) ={

exp(p0 + p1 t)(α(x) = |p1 |)(3)

exp(p0 + p1 t) + exp(p2 + p3 t)(|p1 | > |p3 |, α(x) = |p3 |)(4)

where p0 , p1 , p2 and p3 are fitting parameters and α(x) stands for a decay constant of the counting rates
at the radiator’s position of x. In case that the temporal changes explicitly have two different slopes
between the former part and the latter part of time t, we used the fitting function given in Eq. (4).

103

20

105
counts/0.1s

10

2

10
10

0.5

1 1.5
time (s)

2

2.5

0

4

1 2 3 4 5 6 7 8time (s)

10
1
0

1

x = 63.2 mm

0 0.5 1 1.5 2 2.5 3 3.5 4time (s)

103
102

102

x = 67.4 mm

10

6 8 10 12 14 16
time (s)

103

2

10

x = 67.0 mm

2

104

4

103

103

1
0

x = 62.8 mm

counts/0.1s

10

104

102

10

10 10 20 30 40 50 60 70 80
time (s)40 60 80 100 120
time (s)10510x = 62.4 mm

counts/0.1s

10

x = 62.0 mm

10

103

2

counts/0.1s

10counts/0.1s

counts/0.1s

102

10

104

103

counts/0.1s

counts/0.1s

102

105

104

x = 67.8 mm
5 10 15 20 25 30 35
time (s)100x = 68.2 mm
2040 60 80 100 120
time (s)Fig.4. Tagging rates as a function of the elpased time after the radiator is inserted (first tagging
channle, Ee = 1.3 GeV mode). The radiator position is described in each panel, and each
red line shows the fitted function expressed in Eq. (3) or (4).

The decay constant α(x) were extracted by the fitting for measured points of the position x. Figure
5 shows results for all energy modes of Ee = 1.3, 1.0 and 0.8 GeV. We evaluated the center position andwidth of the circulating electrons by fitting with Gaussian function g(x) given in the following equation)((x − µx )2(5)g(x) = C exp −2σx2

where C denotes a scale parameter of the distribution, µx and σx are the position and width of thebeam, respectively. Table 1 summarizes results of the measurement. The values in the table are themean value of sixteen channels of the tagger. No dependence on the channels of the tagger is foundand errors of the values are smaller than 10−3 mm. The width of the beam can be evaluated by Eq.
(1) using parameters such as the Twiss parameter (β = 3.69 m) and parameters of the accelerator(ϵ = 1.38×10−7 m, η = 0.45 m and dp/p = 6.2×10−4 ). The results of the calculation are also summarizedin Table 1. Uncertanity of the calculation is approximately 10% due to accuracy of the parameters. The
measured values are in agreement with the calculated values in the accuracy. The measured value in the

56
Ee = 0.8 GeV mode is slightly larger than the calculated value. This is because decreasing of emittancein vacuum has significant effect in lower energy of the electron beam.

9

8

8

8

7

7

7

6
5
4
3

expo slope (s-1)

109expo slope (s-1)

109expo slope (s-1)

10

6
5
4
3

6
5
4
3

2

2

2

1

1

1

60 61 62 63 64 65 66 67 68 69 70
radpos x (mm)60 61 62 63 64 65 66 67 68 69 70
radpos x (mm)60 61 62 63 64 65 66 67 68 69 70
radpos x (mm)Fig.5. Decay constant α(x) as a function of the radiator position x. The left, central, and rightpanels show those for the 1.3 GeV, 1.0 GeV, and 0.8 GeV modes, respectively. The red
curve in each panels shows the fitted function expressed in Eq. (5).

Table 1. Central position and width of the horizontal profile of the electron beam at the BM5
radiator position. The caluculated width is given using Eq (1) and the designed values
for the Twiss and other parameters of the BST ring.
Ee (GeV)
1.3
1.0
0.8

center position (mm)
65.19
64.61
64.77

width (mm)
0.73
0.57
0.51

calculated width (mm)
0.77
0.59
0.47

§ 5. Summary

The horizontal electron beam size at the radiator point in the BST ring was measured for the

first time. A scaler was implemented in the MPLM4X module in order to measure counting rates of
the taggers. The beam sizes are 0.73, 0.57 and 0.51 mm for Ee = 1.3, 1.0 and 0.8 GeV, respectively.
The measured widths of the beam are in agreement with the calculated widths in the 10% accuracy.
Evaluation of the beam size by inserting a radiator is one of the important methods that we measureproperties of an electron synchrotron. Measurement of a form of electron beams by a radiator is used asa monitor of circulating electrons in the synchrotron. We expect that the measured properties of electron
beams feed back to operation of the accelerator and evaluation of properties of photon beams.

Acknowledgments
The authors wish to thank the ELPH accelerator staff for providing the electron beam in the stablecondition. They also give I. Nagasawa their sincere gratitude for his technical support in the development of the MPLM4X module. This work was supported in part by Grant-in-Aid for Scientific Research(C) (26400287). One of the authors (Y. O.) would like to thank the Advanced Leading Graduate Course

57
for Photon Science (ALPS) team at the University of Tokyo for giving a chance to participate this interesting measurement.

References[1]

F. Hinode et al.: Journal of Physics: Conference Series 425 (2013) 072011.

[2]

F. Hinode et al.: Proceedings of 2005 Particle Accelerator Conference (2005) 2458.

[3]

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

[4]

F. Miyahara: Internal GeV-γ Analysis Note, 33 (2007).

[5]

I. Nagasawa and T. Ishikawa: Internal GeV-γ Analysis Note, 380C (2015).

58

ELPH Annual Report, Tohoku University (2015)(ELPH Experiment : #2822)

Performance of Undoped CsI Crystal with Both-end
Readout for the KOTO Experiment at J-PARC
H. Nanjo1∗ , H. Haraguchi2 , M. Iwasa3 , H. Kanauchi3† , S. Su4 , T. Sakurai3 ,M. Sasaki3 , Y. Sugiyama2 , Y. Tajima3 , M. Togawa2 , T. Yamanaka2 ,and H.Y. Yoshida31234Department of Physics, Kyoto University, Kyoto, 606-8502, Japan

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

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

Department of Physics, University of Michigan,, Ann Arbor, MI 48109, USA

Both-end readout of undoped CsI crystals was developed in order to distinguish gamma and neutron
for the KOTO experiment at J-PARC. Gamma and neutron can be distinguished with the depth of hits
in the crystal, since the radiation length of gamma is shorter than the interaction length of neutron.
Photon sensors on both ends of the crystal provide information of the depth from the difference of theircorresponding hit times. We report on the performance of the both-end readout using a positron beam,
where a photomultiplier tube was used for one end, and multi-pixel photon counters for the other.

§ 1. Introduction

We are conducting the KOTO experiment [1] at J-PARC to search for the rare CP-violating decay,

KL → π 0 νν. Its branching ratio, B(KL → π 0 νν), is predicted to be 3×10−11 in the Standard Model (SM)with the theoretical uncertainty of ∼1% [2]. Such highly suppressed and well predicted process in the

SM is suitable to explore new physics beyond the SM in higher energy scale. Some new physics models

predict an-order-of-magnitude enhancement of the branching ratio for new physics in the energy scale
1-100 TeV [3–6]. The KOTO experiment searches for such new physics with a single event sensitivity
close to the SM prediction.
The KOTO experiment identifies the decay KL → π 0 νν by requiring only two gammas from a π 0

and nothing else. Figure 1 shows the KOTO detector, into which a narrow collimated KL beam enters.
The “CsI calorimeter” consists of 2716 undoped CsI crystals stacked inside a cylinder 2 m in diameter.
The dimensions of the crystals are 2.5 × 2.5 × 50 cm3 for the inner region, and 5 × 5 × 50 cm3 for the outerregion. The scintillation light is read out by a photomultiplier tube (PMT) attached on the downstream

end of each crystal. The two gammas are detected with the CsI calorimeter, and the hit positions andenergies are reconstructed from the clusters of their hit crystals. The decay vertex is reconstructedby assuming that the two gammas decayed from a π 0 on the beam axis. Neutral pions with larger∗

Present address: Department of Physics, Osaka University, Toyonaka, 560-0043†

Present address: Department of Physics, Tohoku University, Sendai, 980-8578

59          




















Fig.1.














 

Cross-sectional view of the KOTO detector.

transverse momentum are selected in order to reject the decay KL → 2γ. The other detectors are usedas veto detectors in order to ensure “nothing else”, thus rejecting the other KL decays that have charged

particles or more than two gammas in the final state.
Neutrons also exist in the beam, and small fraction of neutrons remains in the beam halo escaping
from the beam collimation. Neurons in the beam halo may hit the veto-detector components near the
beam and generate a π 0 which decays into two gammas and mimics the signal. This type of backgroundis suppressed by requiring the decay vertex to be away from detectors near the beam.
A neutron in the beam halo also can hit the CsI calorimeter directly and generate two clusters. One
cluster is generated from a hadron shower by the incident neutron. The second cluster can be made fromanother neutron generated in the hadron shower which travels in the calorimeter by some distance fromthe first cluster. This two clusters will contribute to background, and this is the main background sourcein the KOTO physics analysis of the data taken in 2013. In the analysis, one event was observed withall the event selection at the sensitivity of 1.29 × 10−8 [7], The observed one event is consistent with the

expected level of this background, which is still high even after cluster shape information (hit patternsof the crystals in a cluster) greatly reduces this background. We are further investigating reduction

methods of this background using cluster shape information and waveform information from the PMT
signals.
In addition to the analysis efforts, we are preparing to add a new hardware to reduce this background, new readout of the scintillation light on the upstream end of the crystal. The timing difference
between the upstream and downstream readouts will provide the depth of the energy deposition in the
crystal. With the depth, one can distinguish between gammas and neutrons because the gamma showers
are localized in the upstream end whereas the location of neutron showers are distributed broadly due
to the difference between the interaction length and radiation length of the crystal. the background by
one order of magnitude at least. Combining the shower depth measurement with analysis cut improvements, reduction of the neutron-induced background by three orders of magnitude is expected, which isenough to reach the sensitivity close to the SM prediction.

60§ 2. Upstream readout

The downstream readout with PMTs in the current KOTO experiment is unchanged in order tokeep the calorimeter performance. For the upstream readout, a multi-pixel photon counter (MPPC) is
planned, which is multi-pixel silicon avalanche photodiode operating in Geiger mode. It enables photoncounting capability with a typical gain of 106 at a relatively low operating voltage around 60 V. The
MPPC, HAMAMATSU Photonics S13360-6050CS, was selected, which had the active area of 6 × 6 mm2 ,the pixel size of 50 × 50 µm2 , and a silicone window. The window material, silicone, makes the MPPC

sensitive to UV photons, which fits the scintillation spectrum of the the undoped CsI with the maximum
scintillation yield at the wavelength of 310 nm. The features of the MPPC are as follows.
• Gain, typically 1.7 × 106• Peak photon detection efficiency of 40% at the wavelength of 450 nm• Sensitivity to UV photons, photon detection efficiency of 20% at the wavelength of 300 nm• Small response to charged particles, single photon level.
• Low mass, 0.6 g for 6 × 6 mm2 sensor• Cost effectivenessFor the future upgrade of the calorimeter with the both-end readout, we will attach one MPPC to each
2.5 × 2.5 cm2 crystal, and four MPPCs to each 5 × 5 cm2 crystal. The total number of MPPCs needed

will be 4096, but the number of readout channels can be reduced to be 256, since fine segmentation
is not needed for the discrimination of neutron and gamma. The design will be achieved with a seriesconnection of four MPPCs, and with an amplifier summing four such outputs.

§ 3. Performance test with positron beam
3.1 Motivation

In this test experiment, we tested the feasibility of measuring the shower depth with the bothend readout. The timing resolution is important, since the discrimination between neutron and gamma
is based on the timing difference between the two readouts. This discrimination was applied after thesignal event selection, requiring the energy of the cluster to be above 100 MeV. The corresponding photoelectron yield of the PMT was 900 with the typical light yield of 9 photo-electron/MeV. The expected lightyield of the MPPC was 90 considering the smaller photon detection area of the MPPC.
3.2 Setup of both-end readout
We prepared an undoped CsI crystal with four MPPCs‡ and a PMT§ as shown in Fig. 2. The crystal
was 50 cm long and 5 × 5 cm2 in cross-section. The PMT was 65 mm in diameter with a quartz window.

A UV transmitting filter¶ was inserted in order to remove slow components of the scintillation light.

‡ HAMAMATSU Photonics S13360-6050CS§ HAMAMATSU Photonics H6521¶ SIGMAKOKI UTVAF-50S-33U

61
Silicone optical joints were also inserted for the good optical contact∗∗ . Four MPPCs were soldered ona printed circuit board (PCB), and another silicone joint was also inserted between the MPPCs and the
crystal.

PCB

Silicone joint

Silicone joint

Undoped CsI crystal

PMT

MPPC
UV transmitting filter
Fig.2.

Setup of the both-end readout.

The four MPPCs were connected in series and bias voltage of 219 V was applied, which corresponded
to the gain of 1.7 × 106 for each MPPC. The output was amplified by a factor of 5 using a commercial
amplifier with the input impedance of 50 Ω.

To study the light propagation speed inside the crystal, we placed the crystal normal to the beam
as shown in Fig. 3, and moved the crystal. Four trigger counters were prepared. The most upstream one
defined the timing with a plastic scintillator 1 cm thick and 5 cm × 7 cm in cross-section. The other three

counters defined the beam size with plastic scintillators 0.5 cm thick and 1 × 1 cm2 in cross-section
MPPC
undoped CsIPositron beam

Trigger counters

PMT

Fig.3.

Setup perpendicular to beam.

To study the energy and the response timing for electromagnetic showers, the crystal was placedparallel to the beam as shown in Fig. 4,

 MOMENTIVE TSE3032∗∗ The PMT and MPPCs were pushed to the crystal with the spring force of 5.6 N.

62
Positron beam
undoped CsI

PMT

MPPC

Trigger countersFig.4.

Setup parallel to beam.

3.3 Data acquisition and waveform
Data was taken with an oscilloscope. The trigger was issued by the coincidence of four trigger
scintillators. The waveforms from the MPPC and the PMT on the crystal were recorded with the input
impedance of 50 Ω, and with the time interval of 0.4 ns. The logic signal for the trigger was also recorded.
The triggered waveforms were acquired through an Ethernet cable
The waveforms of the PMT and MPPC are shown in Fig. 5 and Fig. 6, respectively, which werecollected in the perpendicular setup with 500 MeV/c positrons. The decay time of the PMT pulse was 22
ns, which corresponded to the decay time of the scintillation. The MPPC waveform can be fitted withconvolution of two exponentials with the decay times of 22 ns and 61 ns. The former corresponded to theχ2 / ndf
9468 / 396
Prob
0
p0
-231.6 ± 13.38
p1
39.31 ± 1.264
p2
21.87 ± 0.1855

50
0
-50

Voltage (mV)

Voltage (mV)scintillation decay, and the latter corresponded to the response of the MPPC to a single photon.

0
-50

-100

-100

-150

-150

-200

-200

-250
-200 -100 0

100 200 300 400 500 600 700 800-250-200 -100 0Time (ns)Fig.5.

Waveform from PMT.

χ2 / ndf 7.262e+04 / 1496
Prob
0
p0
-492.6 ± 5.194
p1-3.401 ± 0.1678
p2
61.49 ± 0.5832
p3
22 ± 0p4-15.46 ± 0.2587

50

100 200 300 400 500 600 700 800
Time (ns)Fig.6.

Waveform from MPPC.

The timing was decided from the obtained waveform using constant fraction timing at the half pulse
height. The base line was decided with earlier samples. The highest sample was used to decide the peakheight. The constant fraction timing was decided with the middle height between the base line and peakheight. The energy deposition in the crystal was measured with the area between the base line andwaveform.
3.4 Energy response and calibration
Energy response of the both-end readout was studied in the parallel setup with four momentum
configurations of the positron beam, 200, 400, 600, and 800 MeV/c. The distributions of the energy
deposition for the PMT readout are shown in Fig. 7, and those for the MPPC are shown in Fig. 8.
Figure 9 shows the peak position as a function of the energy deposition in the crystal simulated with
Geant4. Linearity of 3% is obtained for both readouts.

140

180
160
140

120

120

100
80

50

60

70

80

3

0
0

50

100

150

Energy deposit (PMT) (a.u.)

Fig.7.

200

250

300

Fig.8.

1

504.5 ± 2.668
146.1 / 2

p0

0±

1

MPPC

121.3 ± 0.6597

PMT

50

3

×10
400

350

0
0

Energy deposit (MPPC) (a.u.)

Distributions of theenergy deposition with
the PMT readout forthe positron momentum
200 (black), 400 (red),
600 (green), and 800(blue) MeV/c.

0±p1
χ2 / ndf

100

20

×10
100

90

11.52 / 2

150

40

40

300

200 p12030

χ2 / ndf

350 p0

250

60

20

×103

80

40

10

400

100

60

0
0

Output (a.u.)

160

Entries

Entries

63

100

200

300

400

500

600

700

800

Energy deposit (MeV)

Distributions of theenergy deposition with
the MPPC readout forthe positron momentum
200 (black), 400 (red),
600 (green), and 800(blue )MeV/c.

Fig.9.

Peaks of measured
energy deposition as afunction of the energy
deposition
simulatedwith Geant4.
Linearfits are also shown.

3.5 Propagation time and timing difference
The propagation time of the both-end readout was studied in the perpendicular setup by moving theincident position of the beam to -18, -9, 0, 9, and 18 cm, along the 50-cm long crystal, where 0 is at the
middle of the crystal. The momentum of the positron beam was 500 MeV/c. Figure 10 †† shows the timing
distributions for the PMT readout, and Fig. 11 shows those for the MPPC readout. The peak timings areplotted as a function of the beam position in Fig. 12. Linear relations were obtained and the propagation

220
200
180
160
120

120

80
60
40
20

-3

-2

-1

0

1

2

3

4

PMT time (ns)Timing distributions
for the PMT readout
for the beam positions,-18, -9, 0, 9, 18 cm.

43

χ2 / ndf

47.67 / 4

χ2 / ndf

0.01507 ± 0.01065

p0

0.008098 ± 0.005961

0.007987 ± 9.085e-05

p1-0.01067 ± 5.345e-05

2

0

60

-1

40

-2

20

MPPC

-3

PMT

0
-4

-3

-2

-1

0

1

2

3

4

-4
-250 -200 -150 -100 -50

MPPC time (ns)Fig.11.

160.7 / 4

p0
p1

1

80

100

Fig.10.

140

100

140

0
-4

Time (ns)240

Entries

Entriestimes were 10.7 ns/m and 8.0 ns/m for the PMT and MPPC readouts, respectively. This difference may

Timing distributions
for the MPPC readout
for the beam positions.

050

100 150 200 250
Beam position (mm)Fig.12.

Peak times as a function of the beam incident position.

be partially explained with the dispersion of the CsI. The MPPC without a UV-transmitting filter was
sensitive to scintillation with the wavelength larger than 400 nm, whereas the PMT with the UV filter
was only sensitive to the scintillation with the wavelength shorter than 400 nm. The refractive index of
CsI is 2 for the wavelength of 300 nm, and 1.8 for 500 nm. This makes the propagation time with the
MPPC readout shorter by 10%.
The distributions of the time difference between the PMT and MPPC readout are shown in Fig. 13.
The peaks and resolutions in the distributions are shown as a function of the beam position in Fig. 14†† The measurements for the center position were performed twice, the first and the last measurement in this series ofmeasurements, which shows the stability and reproducibility.

100
80
60
40
20
0
-5

Timing resolution (ns)Time difference (MPPC-PMT) (ns)

Entries64

54

χ2 / ndf

3

p0-0.004176 ± 0.008778

p1

0.01865 ± 6.993e-05

2
1

261 / 4

0

-3

-2

-1

0

1

2

3

4

-2

0.35

-3
-5
-250 -200 -150 -100 -50

5

0

50

Distributions of thetime difference in theboth-end readout.

0.3-250 -200 -150 -100 -50

100 150 200 250

050

Fig.14.

Peaks of the time difference as a function of
the beam position.

100 150 200 250
Beam position (mm)Beam position (mm)Time difference (MPPC-PMT) (ns)Fig.13.

0.5
0.45
0.4

-1

-4
-4

0.6
0.55

Fig.15.

Resolutions of the timedifference distribution
as a function of thebeam position.

and Fig. 15, respectively. The linear response can be used to evaluate the scintillation position in the
crystal, and the timing resolution was less than 0.6 ns for the energy deposition of 110 MeV. The worse
resolution in the downstream region (positive side in the position) is explained with smaller light yieldmeasured in the MPPC readout for the region. The effective propagation time was 18.65 ns/m, whichcorresponded to 9.3 ns for the maximum time difference in the 50-cm long crystal. The timing resolution
corresponds to the position resolution of 3.2 cm.
3.6 Timing difference for electromagnetic shower
The time difference of the both-end readout for the electromagnetic shower was studied in theparallel setup with the positron momentum of 200, 400, 600, and 800 MeV/c. Figure 16 shows the
distributions of the time difference, which is interpreted that the position of the electromagnetic shower
was reconstructed near the upstream end due to the short radiation length. The time difference of−3.2 ns corresponded to 79 mm (4.2 radiation length) deep from the upstream surface of the crystal.
It is similar to the shower maximum position, 2.4-3.8 radiation lengths for the momentum range. The

timing resolution less than 0.6 ns was achieved, which was better than our expectation 0.8 ns from thePbeam=200 MeV/c

200

Pbeam=400 MeV/c

150

Pbeam=600 MeV/c

100

Pbeam=800 MeV/c

-3.05
-3.1
-3.15
-3.2

-4

-3

-2

-1

0

1

2

3

4

5

Distribution of thetime difference in theparallel setup.

0.6
0.5

0.2
0.1
100

200

300

400

500

600

700

800

0
0

Energy deposit (MeV)Time difference (MPPC-PMT) (ns)Fig.16.

0.8
0.7

0.3

-3.3

-3.4
0

1
0.9

0.4

-3.25

-3.35

50
0
-5

-3

Timing resolution (ns)250Time difference (MPPC-PMT) (ns)

Entriessimulation study.

Fig.17.

Peaks of the time difference as a function of
the deposition energy
in the crystal

100

200

300

400

500

600

700

800

Energy deposit (MeV)

Fig.18.

Width of the time difference as a function of
the deposition energy
in the crystal.

65§ 4. Conclusion

We first demonstrated the performance of the both-end readout with a PMT and MPPC for the

undoped CsI crystal. By using the timing difference of the both-end readout, the depth of the energy
deposition in the crystal was obtained with the resolution better than 3.2 cm for the incident positron
momentum larger than 200 MeV/c.

Acknowledgment
We would like to express our gratitude to the staff of the Research Center for Electron Photon
Science. Part of this work is supported by JSPS/MEXT KAKENHI Grant Number 23224007.

References[1]

T. Yamanaka for the KOTO Collaboration, PTEP 2012, 02B006 (2012).

[2]

A. J. Buras, D. Buttazzo, J. Girrbach-Noe and R. Knegjens, JHEP 1511, 033 (2015).

[3]

A. Buras, PoS FWNP , 003 (2015).

[4]

M. Blanke, A. J. Buras and S. Recksiegel, Eur. Phys. J. C 76, no. 4, 182 (2016).

[5]

M. Blanke, PoS KAON 13, 010 (2013).

[6]

M. Tanimoto and K. Yamamoto, PTEP 2015, no. 5, 053B07 (2015).

[7]

K. Shiomi for the KOTO Collaboration, Proceedings of the 8th International Workshop on the CKM
Unitarity Triangle (CKM 2014), Vienna, Austria, September 8-12, 2014.

66

ELPH Annual Report, Tohoku University (2015)(ELPH Experiment : #2832)

Test of an X-ray flat panel sensor as a beam profile monitor
H. Kanda1 , K. Honda1 , T. Ishikawa2 , M. Kaneta1 , K. Maeda1 , M. Miyabe2 ,Y. Muroi1 , W. Nakai3 , S. N. Nakamura1 , A. Ninomiya1 , Y. Obara3 , K. Ozawa4 ,K. Ozeki1 , T. Sasaki1 , H. Shimizu1 , and A. O. Tokiyasu2
12

Graduate School of Science , Tohoku University, Sendai 980-8578, Japan

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

4

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, Japan

We have been developing a beam profile monitor for 1 GeV region gamma-ray beams using an X-ray
flat panel sensor. It consists of a thin inorganic scintillator for X-rays and a CMOS area sensor. For
obtaining the profile of the 1 GeV region gamma-ray beams, carriers induced by the passing of gammaray photons and e± converted from them are accumulated in its pixels. We tested its sensitivity andlinearity to the gamma-ray photons with various types of converter plates. It was found to be dependent
on the thickness of the converter in X0 . We also tested its accuracy by the x and y spreads of the profileof the gamma-ray beams and the positron beams. The gamma-ray beam profile was consistent withthe one measured with a beam profile monitor consisting of scintillation fiber hodoscopes triggered incoincidence with a hit on a tagging counter corresponding to a 1 GeV photon. The positron beam profile
was consistent with the one measured with a Gas Electron Multiplier tracker. From these results,
sufficient sensitivity and accuracy were expected to the X-ray frat panel sensor for the use of the beamprofile monitor.
Diagnosis of a beam is one of the matters of importance for defining and optimizing the experimental
condition in beam experiments. 1 GeV region tagged photon beams are provided at The Research Center
for Electron Photon Science (ELPH), Tohoku University. The beams are produced by bremsstrahlungof 1.3 GeV electrons on the carbon fiber target. Energy of emitted photon are tagged with tagging
counters which measures the momentum analyzed electrons after the photon emission [1, 2]. Several
kinds of beam profile monitor (BPMs) for 1 GeV region gamma-ray beams have been developed and in
use at ELPH. They are used for monitoring and tuning the gamma-ray beams. One consists of plastic
scintillator hodoscopes to detect the electron and positron converted from the photon (HSBPM) [3]. It isremote-controllable, real-time, and radiation-hard. However, it needs signal processing electronics anda data acquisition system which usually push up its price. The width of one segment of the hodoscopes
was 3 mm. It is sufficient for finding the center of the beam. But it is not sufficient to inspect reasonof deformation of a beam profile if it is deformed. The other one consists of a lead plate and an instantphotographic film (Gamma Camera). It is compact and with good spatial resolution. However, it needs

67
manual development process and its linearity is not guaranteed. A new kind of the BPM which combinescompactness, spatial resolution and remote-controllability was waited for.
One of the candidates was an X-ray Flat Panel Sensor (XFPS). It is an area sensor widely used for
the X-ray diffraction, the medical X-ray imaging, and the nondestructive testing [4]. It has advantages
over other kinds of X-ray imaging devices as a following list:
over X-ray films better linearity, digital data acquisition and repetitive use
over Image intensifier cameras compactness and freedom from distortions
over Imaging plates instant imaging.
We adopted a Remote RadEye2 manufactured by Rad-icon Corporation [5] for the test. It consists ofa thin inorganic scintillator, Kodak Min-R2190 [6, 7], for the absorption of X-ray photons and a CMOS
area sensor for the detection of visible lights emitted from the scintillator (Fig. 1). Because the thicknessof the scintillator is 47 µm and the base material of the CMOS sensor is a silicon, the sensitivity of the
XFPS to the 1 GeV region gamma-ray was expected to be low. We added a converter plate to increase its
sensitivity. The principle of gamma-ray detection is also demonstrated in Fig. 1. The converter absorbs
the X-ray photons but converts the gamma-ray photons with sufficient energy to electrons and positrons
which travel through the scintillator and the CMOS sensor for induction of the signal to the CMOS
sensor.
The Remote RadEye2 consists of a compact sensor head and an electronic circuit box. The size ofthe sensor head is a 111.0 × 77.5 × 24 mm3 with a 49.3 × 49.2 mm2 effective area. A DVI cable was used

for the connection between the sensor head and the circuit box. It enables the freedom of the locationof the sensor head. The electronics module is connected to a Windows PC for the data acquisition witha Gigabit Ethernet. Thus the remote monitoring of the beam profile is achieved. The characteristics ofthese BPMs are summarized in Table 1. The spatial resolution of the HSBPM in the table was estimatedas an ideal resolution expected for 3 mm pitch pixel size. Its unit, lp/mm, means the number of pairsof black and white lines resolvable with 50% contrast. Another unit ppi is an abbreviation of pixels
per inch. A BPM for the 1 GeV region gamma-ray beams with linearity, spatial resolution, and remotemonitoring was expected with the XFPS.
Table 1. Comparison of the characteristics of the detectors for the beam profile monitoring.

Spatialresolution
Fiducial size
Whole size
Data

Gamma Camera(w/ Polaroid 53)
12 − 14 lp/mm

HSBPM

XFPS

0.16 lp/mm (8.5 ppi)

131 × 106mm2
200 × 150 × 30 mm3Photographic image

10 lp/mm (530 ppi)
3.5 lp/mm w/ Min-R2190
49.3 × 49.2mm2111 × 77.5 × 24 mm3
Pixel Brightness

Detector

Pb converter +AgBr

48 × 48mm2
420 × 420 × 246 mm3Counts of the e± hitson the scintillator
Al converter +Plastic Scintillator

Remote monitoring

Not possible

Possible

Converter +Gd2 O2 S:Tb +CMOS image sensor
Possible

68

X-ray -ray X-ray -ray

Converter plate (lead etc.)

Added for sensitivity to gamma-rays
Graphite cover
Polyurethane foam
Flexible scintillator

Visible lightelectron positron

CMOS sensor withceramic substrate}

Components of XFPS

Direct signal inductions ona silicon semiconductor

Fig.1. Schematic view of the cross sectional structure and the principle of gamma-ray detectionof the RadEye2 sensor.

We tested the sensitivity of the XFPS with various converter plates. The materials and the thicknesses of the converter plates were 1 mm Al (0.011 X0 ), 2 mm Al (0.022 X0 ), 4 mm Al (0.045 X0 ) 8 mm
Al (0.090 X0 ), 10 mm Al (0.11 X0 ), 1 mm Cu (0.07 X0 ), 2 mm Cu (0.14 X0 ), 4 mm Cu (0.28 X0 ), 0.5 mm
Pb (0.089 X0 ), 2 mm Pb (0.36 X0 ), and 4 mm Pb (0.71 X0 ). The tagged photon beam with intensity of approximately 2 MHz for the tagged region (60 MHz including the untagged region) were irradiated on the
XFPS with the converter. The XFPS was placed 10 m downstream of the target for the bremsstrahlung.
The accumulation time was set as 1 s. We obtained 5 images before the exposure as the backgroundand 5 images during the exposure. The averaged background image was subtracted from the averaged
beam image to obtain a image data for the beam profile. An example of the image obtained with a 4
mm Cu converter is shown in (Fig. 2(a). A region of interest (ROI) is shown as an black open box in
Fig. 2(a). The brightnesses of the pixels in the ROI was averaged for the test of the sensitivity. The
averaged brightness with a normalization to the number of irradiated photons is shown as a function of
the material thickness(x) in a unit of X0 in Fig. 2(b). It was well fitted with a function:f (x) = C1 Ne± (x) + C2 Nγ (x),

(1)

)
(
where Ne± (x) = 2 1 − exp(− 97 x) denotes the number of e± converted from the gamma-ray photon

increasing with x and Nγ (x) = exp(− 79 x) denotes the number of the gamma-ray photon of the beam

decreasing with x. The strong dependence on Ne± suggests the linearity of the brightness to the numberof e± . The intensity of the X-ray emission due to the ionization by the passage of e± was considered tocorrelate to Ne± . But its contribution cannot be separated from this measurement. Monte Carlo study
with a detailed electromagnetic interaction with the EGS5 [8] is currently underway.
We compared the profile of the 1 GeV region gamma-ray beams with the one measured with the
HSBPM. The intensity of the gamma-ray beams was typically 10 MHz for the tagged region (300 MHz
including the untagged region). The distance from the target for the bremsstrahlung was 20 m and thus

ROI

250
200

Brightness (ADU)

300

(a)

Brightness (ADU)

69

200
180

Pb
Al
Cu
non
Scaled Nγ
Scaled Ne+Nγ

(b)

160
140
120

150

100
80

100
50

60
40
20

0

0
0

0.1

0.2

0.3

0.4

0.5

0.6

0.7
0.8
0.9
Thickness x (X )0

Fig.2. An example of the image data for a gamma-ray beam profile obtained with a 4 mm Cu
converter plate (a). A region of interest for the test of sensitivity is shown as a black open
box. The averaged brightnesses with Cu (small open circle), Al ( closed circle), and Pb(open circle) converters and without any converter (small closed circle) are shown as afunction of their thickness in X0 . The fitting function (solid curve) and its gamma-ray
photon component (dotted curve) are drawn.

the flux density was almost similar to the previous test of sensitivity. Thus the accumulation time of 1s was sufficient for obtaining the beam profile with the XFPS. We found that the HSBPM suffered thebroad spread of multiple-scattered e± generated from the the low energy photons (Eγ < 0.2 GeV) by aMonte Carlo simulation. In order to reduce the broad spread, the HSBPM was triggered in coincidencewith a tagging counter corresponding to Eγ = 1 GeV. The obtained profiles and their horizontal (x) andvertical (y) projections are shown in Fig. 3. These projections were fitted with a sum of two Gaussianfunctions. The spread was evaluated as the standard deviation (S) of the fitted function. It was obtained
from the height (hi ), mean (mi ) and σ (σi ) of i-th Gaussian function with a following formula:

M=

2
∑

hi m i σi

i=1
2
∑

(2)
h i σi

i=1

�
� 2
�∑
�
hi σi (σi2 + (mi − M )2 )
�
� i=1
S=�
.
�
2
∑
�
�
hi σi

(3)

i=1

The result of the fitting is summarized in Table 2. The x and y spreads of the positron beam profile
obtained with the XFPS was consistent with the ones obtained with the HSBPM.
We also measured the profile of 400 MeV/c positron beam at the ELPH test beam line. A trigger
counter, a Gas Electron Multiplier (GEM) tracker [9] and the XFPS was aligned on the positron beamline from the upstream. The distance between the GEM tracker and the XFPS was minimized as 50
mm to assure that x and y positions of a positron passing through the GEM tracker were the same70

Fig.3. The gamma-ray beam profiles obtained with the X-ray flat panel sensor (c) and the HSBPM (f). Panels (a), (b), (d), and (e) show x-projection of (c), y-projection of (c), x-projectionof (f), and y-projection of (f), respectively. Each projection was fitted with a sum of two
Gaussian functions.

Table 2. Summary of the x and y spreads of the 1 GeV region gamma-ray beams measured with
the XFPS and the HSBPM.
XFPS
HSBPM

x spread (mm)9.5 ± 0.1
9.6 ± 1.0

y spread (mm)12.1 ± 0.2
12 ± 1as those passing through the XFPS. Strips with 350 µm pitch in x direction and 1400 µm pitch iny direction were used for the readout of the signal from the GEM tracker. Two dimensional positionof a charged particle can be obtained using the GEM tracker with better than 100 µ m resolution in
Gaussian σ for the x direction. It was thus expected to be the optimum position sensitive detector totest the resolution of the XFPS. The typical intensity of the positron was 4 kHz. We took typically 10
beam images with 1 s accumulation during the beam exposure period and 2 background images during
the beam stop period. In total, 3000 beam images and 600 background images were obtained in 1.5
hours. The summed background was multiplied by approximately 5 and subtracted from the summed
beam image. The hit positions on the GEM tracker were recorded at the same time. Because of the
DAQ efficiency of the GEM tracker, approximately 50% of the positrons passing through the setup wererecorded. The obtained profiles and their x and y projections are shown in Fig. 4. These projections werefitted with a Gaussian function for the evaluation of the spread of the beam. A fixed error was set to all
the data points of x and y projections of the beam profile obtained with the XFPS. It was estimated withthe fluctuation of the base line after the subtraction of the background. Statistic errors were set to all
the data points of x and y projections of the beam profile obtained with the GEM tracker.

(b)

20

Brightness (ADU)(a)

y (mm)

Brightness (ADU)

Brightness (ADU)

71

(c)

10
0
-10
-20

-10

0

10

-20

20

-10

0

10

-10

0

10

(e)

20

x (mm)y (mm)CountsCounts-20

y (mm)x (mm)

(d)

20

20

Counts

-20

(f)

10
0
-10
-20
-20

-10

0

10

20

x (mm)

-20

-10

0

10

20

-20

-10

y (mm)010

20x (mm)

Fig.4. The profiles of a positron beam obtained with the X-ray flat panel sensor (c) and the
GEM tracker (f). Panels (a), (b), (d), and (e) show x-projection of (c), y-projection of (c),x-projection of (f), and y-projection of (f), respectively. Each projection was fitted with aGaussian function.

The Gaussian σs obtained by the fitting and their errors are summarized in Table 3. Because of
the dead channels of the GEM tracker in x direction, the result of the fitting was varied with changing
the region of interest for fitting. Thus the range of the σs was given in the table. The x and y spreads ofthe positron beam profile obtained with the XFPS was consistent with the ones obtained with the GEM
tracker.
Table 3. Summary of the x and y spreads of the 400 MeV/c positron beam measured with the
XFPS and the GEM tracker.
XFPS
GEM tracker

x spread (mm)13.6 ± 0.2
12.4 − 13.5

y spread (mm)3.2 ± 0.1
3.36 ± 0.01

In summary, we tested the XFPS to be used as the beam profile monitor for 1 GeV region gammaray beams, regarding on the sensitivity and accuracy by comparing the output for various matter andthickness of converter plates using 1 GeV region gamma-ray beams. It was found to be dependent on the
thickness of the converter in X0 and linear to the number of passing e± . The beam profile of the gammaray photons of a few tens of MHz were measured using a 1 mm thick lead plate with accumulation time of
1 s with sufficient sensitivity. The x and y spreads of obtained beam profile was consistent with the ones
measured for 1 GeV gamma-ray beam with the HSBPM. The x and y spreads of the beam profile of the
400 MeV/c positron beam was consistent with the ones measured with the GEM tracker. It also suggests
the sufficient linearity to the number of positron passing through the XFPS. It is the first application of
the XFPS to the gamma-ray beam monitor. A software for easy image acquisition synchronized to the72beam spill is currently developed. It will provide more efficient monitoring and tuning method for the
gamma-ray beams.

Acknowledgment
We would like to thank the administration and technical staff in ELPH for their support.

References[1]

H. Yamazaki et al.: Nucl. Instr. and Meth. in Phys. Res. A 536 (2005) 70.

[2]

T. Ishikawa et al.: Nucl. Instr. and Meth. in Phys. Res. A 622 (2010) 1.

[3]

M. Nanao, T. Ishikawa, and H. Shimizu: Research Report of Laboratory of Nuclear Science, Tohoku
University 36 (2003) 56.

[4]

Hamamatsu Photonics K.K.: Opto-Semiconductor Handbook (2014).

[5]

T. Graeve and G. P. Weckler, in Proc. SPIE Vol. 4320 (2001) 68.

[6]

Michael Farrier, Thorsten Graeve Achterkirchen, Gene P. Weckler, and Alex Mrozack: IEEE trans.
Elec. Dev. Vol. 56 (2009) 2623.

[7]

Eastman Kodak Company: CAT No. 173 9473 (2006).

[8]

H. Hirayama et al.: The EGS5 Code System, Stanford Linear Accelerator Center Report SLAC-R730 (2005).

[9]

K. Kanno et al.: Nucl. Instr. and Meth. in Phys. Res. A 819 (2016) 20.

ELPH Annual Report, Tohoku University (2015)73(ELPH Experiment : #2835)

Performance Test of a Sampling Calorimeter for the
SPring-8/LEPS2 experiment
A. O. Tokiyasu1 , M. Yosoi2 , H. Goto2 , Y. Yanai2 , and M. Miyabe1
1Research Center for Electron Photon Science, Tohoku University, Sendai 982-0826
2

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

In the SPring-8/LEPS2 experiment, we will use a sampling calorimeter system to measure theenergies of γ-rays from hadron decays. We performed a test experiment using a positron beam with theenergy upto 650 MeV, and investigated the performance of the calorimeter. The energy resolution of thecalorimeter was found to be 13% for 250-MeV positrons, and the time resolution was found to be 300 ps.

§ 1. Introduction

In the SPring-8/LEPS2 experiment, we will study hadron photo-production processes by using ahigh-intensity photon beam [1]. The photon beam will be produced by the backward Compton process,and tagged by the tagging counter at the energy ranging from 1.4 to 2.9 GeV. The beam will be injected
to a liquid hydrogen or deuterium target, and exotic hadrons will be searched for. One of the physics
motivations of the SPring-8/LEPS2 experiment is the study of Λ(1405) structure [3]. Λ(1405) can betreated as a composite of two dynamically-generated KN bound state and Σπ resonance. Λ(1405) istagged in the Σ0 and π 0 decay channel, and subsquently the Σ0 and π 0 decay into Λγ and 2γ, respectively.
The energy of γ-rays to be detected ranges from 10 to 400 MeV.
A new spectrometer system, which is under construction, will be used to detect the charged andnon-charged particles. Figure 2 is a schematic view of the spectrometer. The γ-rays from the hadron
decays are detected by a sampling calorimeter, called the Barrel-γ. Barrel-γ is the segmented sampling
calorimenter system made up of 1 mm thick leads and 5 mm thick plastic-scintillator plates. Barrel-γ isoriginally developed for the BNL-E787 experiment to identify π 0 . The configuration and the performanceare reported elsewhere [2].
The acceptance and experimental resolution are estimated by a Monte-Carlo simulation. In thesimulation, the detector responses like the energy resolution are implemented as input parameters. To
improve the precision of the simulation study and check the experiment feasibility, we need to know thedetecrtor responses as input parameters.
Therefore, we performed a test experiment to investigate the performance of Barrel-γ. Barrel-γ
has already been installed in the spectrometer, then we used the BV-liner detector in the BNL-E949
experiment to investigate the performance. The configuration of the BV-liner is shown in Fig.3, whichcontains 13 layers of 5 mm thick plastic-scintillator and 12 laysers of 1 mm leads. The material of BVliner is the same as the one of Barrel-γ. By testing the performance of BV-liner and comparing the

74

Fig.1. Correlation between the emitted angle and the energy in the laboratory system of γ fromthe Λ(1405) decay. Left: γ from Σ0 decay. Right: γ from π 0 decay.

Fig.2. Schematic view of the LEPS2 spectrometer. Barrel-γ is shown as a green part in the
figure.

experimental data with the simulation, we can extract the information of Barrel-γ.
We performed the test experiment at the positron beamline for testing detectors in the ResearchCenter for Electron Photon Science, Tohoku University. Positron beam was exposed to the three BVliner’s with the different energy conditions. Energy resolution and timing resolution were measured foreach BV-liner.

75

Fig.3. The cross section of the BV-liner. the unit in the figure is cm.

§ 2. Performance Test
2.1 Setup

The experimental setup is shown in Fig.4. Three BV-liners were installed perpendicularly along thepositron beam axis. In front of the calorimeters, the defining counter T1 was installed. T1 is a 5-mm
thick plastic-scintillator with the area of 10 x 10 mm2 , on both sides of which PMT’s are attached to readout the light signal. T1 is installed in the center of the detectors and used to define the beam area intaking data.

Fig.4. Setup of the test experiment. The positron beam was injeced from the left direction andhit T1 and three BV-liners.

The detector signals were degitized with NIM modules, and the trigger for the data taking was
produced by the T1 signal. ADC(charge information of the signal) and TDC(timing information of thesignal) were obtained with CAMAC system. The schematic diagram of the data taking system is shownin Fig.5.

76

Fig.5. Data taking system of the experiment.

2.2 Experimental condition
The beam energy was varied by changing TAGX magnetic field [4]. We performed the experimentby using the beam with the energy of 50, 100, 150, 250, 350, 450, 500, 550 and 650 MeV. The beamenergy spread is sufficiently smaller than the detector resolution.
In additon, the setup was tilted by the 16.5 degree to the beam axis, and the beam with the energy of
50, 150, 350 and 550 MeV was exposed to the detectors. For each condition, approximately 105 positrons
were injected to the setup in total.

§ 3. Result

3.1 ADC spectrum
ADC historams for different beam energies were shown in Fig.6. In that figure, ADC values of three

BV-liners were summed up. The detector gain was calibrated by using comic-ray run without beam. The
MIP values were obtained by cosmic-ray run, and the relative gain of each detector was determined.
Each ADC histogram was fitted with a gaussian function. The fitting results were shown in Table.1.
Here, the value σ/mean is corresponding to the energy resolution. The energy resolution measured wasapproximately 13% at 250 MeV. Mean values of ADC histograms with respect to varying beam energies
are plotted in Fig.7. Fitting results with linear function are also shown in the same figure. The deviationfrom the linear fuction becomes large from 220 MeV because the leakage effect cannot be ignored when
the beam energy becomes large. The linearity of the measured energy is introduced below 220 MeV.
3.2 Time resolution
Time resolution was also measured in the experiment. The mean value of both PMTs’ TDC in eachcalorimeter is used to eliminate of position dependence of the timing. In addition, to correct the timing
jittering effect of ADC, the slewing correction method was applied. Typical correlation plot of TDC and
ADC is shown in Fig.8. The time resolution was determined to be approximately 300 ps. This value iscorresponding to the position resolution of 5 cm.

77

Fig.6. ADC histograms for different beam energies.

3.3 GEANT4 simulation
To understand the experimental result, a Monte-Carlo simulation based on GEANT4 was performed. In the simulation, the calorimeter geometry was implemetend, and the positron beam was

78

Table 1. The fitting results of the spectrum for each condition.
E[MeV]
50
100
150
250
350
450
500
550
650

Mean[ch]
35.89
76.57
113.7
191.4
261.8
338.8
378.4
412.6
458.5

Mean err[ch]
0.66
0.95
1.1
1.6
2.4
2.9
0.3
3.1
2.6

σ
10.54
14.14
18.71
25.25
34.88
38.71
38.42
42.8
46.32

σ err [ch]
0.37
0.52
0.64
0.91
1.3
1.56
1.66
1.8
1.45

σ/mean [%]
29.4
18.5
16.5
13.2
13.3
11.6
10.2
10.4
10.1

Fig.7. Mean Values of energy histogram with respect to beam energy.

Fig.8. A correlation plot of TDC and ADC of the calorimeter. Left: the plot w/o slewing correction. Right: the plot with slewing correction.

injected with the energy upto 250 MeV, which is the maximum energy keeping the linearity. Figure 9shows the comparison of the energy resolution obtained by the experimental data and the simulation,in which abscissa is injected beam energies. The resolution obtained by experimental data is a little
larger than the simulated one. In the simulation, there are effects we have’t considered, such as the79light attenuation. However, we can say they are consistent and show the same behavior with respect tothe beam energy.

Fig.9. Comparison of Energy resolution between experimental data and simulation. Data points
with only error bars√are simulated results. Green line is the fitting results of the√ experimental data with a/ E. Red line is the fitting results of the simulation with a/ E.

For the more details of the above discussion, see ref. [5] [6].

§ 4. Summary

We performed a test experiment to investigate the performance of the sampling calorimeter (Barrel-γ) for the SPring-8/LEPS2 experiment. The positron beam at the energy ranging from 50 to 650 MeV
was exposed to three calorimeters which are composed of the same materials as Barrel-γ . The energy
resolution and time reolution of the calorimeter were found to be 13% at 250 MeV and 300 ps, respectively. The results were compared with the Monte-Carlo simulation, and they are almost consistet witheach other.

Acknowledgment
We would like to express our gratitude to staff of the Research Center for Electron Photon Science
for the accelerator operation and the fruitful discussion during the experiment. Part of this work was
supported by JSPS KAKENHI(No. 15H00839).

References[1]

N. Muramatsu et al.: Few Body Syst.54 (2013)7[2]

M.S. Atiya et al.: Nucl.Inst.Meth. 321 (1992) 129.

[3]

T. Hyodo and D. Jido: Prog.Part.Nucl.Phys.67 (2012) 55.

[4]

K. Maruyama et al.: Nucl.Inst.Meth.A376 (1996) 335.

80
[5]

H. Goto: Master theis in RCNP (2016).

[6]

Y. Yanai et al.: JPS Meeting at Sendai, Japan (2015 Mar.).

ELPH Annual Report, Tohoku University (2015)

81

Longitudinal uniformity of the manufactured BGO crystals
for the BGOegg calorimeter
R. Yamazaki1 , T. Ishikawa1 , D.N. Grigoriev2,3,4 , R. Hashimoto1 , Q. He1 ,Y. Honda1 , G.N. Kuznetsov5 , S. Masumoto6 , M. Miyabe1 , N. Muramatsu1 ,M. Nakamura1 , Y. Taniguchi1 , Y. Tsuchikawa1 , H. Shimizu1 , Ya.V. Vasiliev5 ,and H. Yamazaki1
1Research Center for Electron Photon Science (ELPH), Tohoku University, Sendai 982-0826,
Japan
2

Budker Institute for Nuclear Physics, Siberian Branch of Russian Academy of Sciences,
Novosibirsk 630090, Russia
3

Novosibirsk State Technical University, Novosibirsk 630092, Russia
45Novosibirsk State University, Novosibirsk 630090, Russia

Nikolaev Institute of Inorganic Chemistry, Siberian Branch of Russian Academy of Sciences,
Novosibirsk 630090, Russia
6

Department of Physics, University of Tokyo, Tokyo 113-0033, JapanAn electromagnetic calorimeter, called BGOegg, consisting of 1,320 BGO crystals has been constructed at ELPH. All the crystals have been manufactured at the Nikolaev Institute of Inorganic Chemistry (NIIC) in Novosibirsk, Russia. Each crystal for the calorimeter takes a tapered shape, and surface
roughness of the lateral sides is adjusted so as to achieve uniform light output as a function of the distance from the window of the photomultiplier tube. The relative light output and longitudinal uniformity
measured at NIIC for each manufactured crystal with a wrapping material of Al foil are presented. The
relative light output and longitudinal uniformity of the first crystal for each polar angle are also measured at ELPH with three wrapping materials — Vikuity Enhanced Speculator Reflector (ESR) from 3M
company, DuPoint Tyvek 1082D, and Al foil. An excellent light output and longitudinal uniformity has
been obtained for the crystals wrapped with ESR.

§ 1. Introduction

An electromagnetic (EM) calorimeter, called BGOegg, has been constructed at the Research Cen-

ter for Electron Photon Science (ELPH), Tohoku University to study the structure of hadrons via thephoto-induced reactions [1]. Meson photoproduction experiments [2–4] have been conducted with an
EM calorimeter, FOREST [5], for baryon spectroscopy at ELPH [5]. Here, neutral mesons decaying into
photons are mainly detected. We plan to extend meson photoproduction experiments for baryon spectroscopy using a laser Compton scattering photon beam with Eγ = 1.3–2.9 GeV [6] at LEPS2 [7]. We
also plan to search for η ′ mesic nuclei [8], which are good probes for revealing the properties of the η ′meson at finite density [9], by looking at the missing mass spectra for the A(γ, p) reaction. The detec-

82tion of daughter particles from the η ′ -mesic nucleus decay is necessary to reduce the huge backgroundoriginating form the quasi-free single- and multi-meson production processes. We plan to detect an η
meson and a nucleon N from the η ′ N → ηN conversion in a nucleus.

The energy of photons to be detected ranges from several ten MeV to a few GeV in these experi-ments. The high energy resolution is required for the photon measurements, and a large solid angle
is desired for detecting photons and other particles. We have constructed the BGOegg calorimeter consisting of 1,320 BGO crystals for the experiments at SPring-8/LEPS2. The details of the design forthe calorimeter are described elsewhere [10, 11]. Since a crystal for the calorimeter takes a tapered
shape, significant longitudinal non-uniformity of light output is observed due to the focusing effect when
all the surfaces are polished. To achieve uniform light output as a function of the distance from thewindow of the photomultiplier tube (PMT), surface roughness of the lateral sides is adjusted. A test
for the prototype BGO crystals with two different surface conditions (polished and etched) is described
elsewhere [11].

§ 2. Measurement at NIIC

All the crystals have been manufactured at the Nikolaev Institute of Inorganic Chemistry (NIIC)

in Novosibirsk, Russia. Surface roughness of the lateral sides is adjusted by chemical etching so as toachieve uniform light output as a function of the distance from the PMT window. The relative light output and longitudinal uniformity are measured at NIIC for each manufactured crystal. The crystal type
numbers 12F–00F, and 00B–08B in Ref. [10] are converted into 01–13, and 14–22, respectively, to givethe increasing crystal numbers according to the polar angles. The relative light output and longitudinal
uniformity were measured for all the manufactured crystals by using γ rays from a radioactive source,137

Cs (662 keV) or 22 Na (511 keV). A crystal was wrapped with Al foil, and was connected to a 3-inch

PMT, Hamamatsu Photonics R1307. The distances from PMT were set to 10, 60, 110, 160, and 210 mm
using a lead aperture for the source. The light output was given by the centroid of the peak corresponding to the photoelectric effect with a room temperature correction to 23◦ C (−1.5%/◦ C). The light output
for each crystal was estimated by averaging five distance data. Fig. 1 shows the average light output
for all the polar angle numbers of the crystals (01–22). The average light output for each polar angle
number ranges from 1500 to 2000. The average light output for the backward crystals (14–22) is stable,
being approximately 2000. The decrease of the average light output was observed for small crystals(01–03 and 20-22).
The relative light output was also determined among the same polar angle number. Here, therelative light output was normalized so that the average of all the 60 crystals in a polar angle should be
1. Fig. 2 shows the relative light output as a function of the crystal number at each polar angle. The polar
angles are specified in the crystal types (12F–00F, and 00B–08B). Some crystal types (12F, 11F, 04B, and03B) show a large gap between the different shipping dates. Although the shipping date was the same, alarge gap exists in 04F and 03F, suggesting the dates of the manufacture or measurement were different
between them. The relative light outputs range from 0.9 to 1.1, especially those are approximately 1 for83

Average light output (a.u.)

2500
2000
1500
1000
500
0

0

2.5

5

7.5

10
12.5
Ring number

15

17.5

20

22.5

Fig.1. Average light output for all the polar angle numbers of the crystals (measured at NIIC).
The average light output is given for averaging all the 60 crystals in the same polar angle.
The 08–10 (05F–03F) crystals are measured by irradiating the 511 keV γ rays from the22
Na radioactive source, and those of the others are measured by irradiating the 662 keVγ rays from the 137 Cs. The red boxes shows the corresponding light output for the 137 Cs
irradiation.
the 01F –01B crystals.
The longitudinal uniformity U was also investigated. Here U is defined asUi =Li − L,L(1)and determined for each distance for each crystal. The Li denotes the light output for each measurement,
and L denotes the average of the five measurement of each crystal for different distances from the PMT
window. Fig. 3 shows the uniformity U as a function of the distance from the PMT window. The U iswell controlled within ±5%, giving the high energy resolution (1.36% at 1 GeV) for a prototype BGO
calorimeter consisting of 25 crystals arranged in 5 × 5 matrix [10, 11]. The further small values of U canbe obtained by wrapping a crystal with a film, Vikuity Enhanced Speculator Reflector (ESR) from 3M
company, as discussed below.

§ 3. Measurement at ELPH

The light output and longitudinal uniformity for one out of the 60 crystals were measured also at

ELPH. Each crystal was wrapped with three materials, Vikuity Enhanced Speculator Reflector from
3M company, DuPoint Tyvek 1082D, and Al foil. The measurement of the 00B crystal was omitted
since the shape of the 00B crystal is identical to the 00F crystal. The crystal was connected to a PMT,
Hamamatsu Photonics H6410 through optical grease, OKEN6262A. A series of the measurements weremade from December 20, 2011 to June 2, 2012. The supplied high voltage was −2000 V during the series

Ralative output

84

1.2
1.1
1
0.9
0.8
1.2
1.1
1
0.9
0.8
1.2
1.1
1
0.9
0.8
1.2
1.1
1
0.9
0.8
1.2
1.1
1
0.9
0.8
1.2
1.1
1
0.9
0.8

0

20

12F

11F

10F

09F

08F

07F

06F

05F

04F

03F

02F

01F

00F

00B

01B

02B

03B

04B

05B

06B

07B

08B 0

40

60
0

20

20

40

60
0

20

40

60

40 60
Crystal number

Fig.2. Relative light output as a function of the crystal number at each polar angle (measured
at NIIC). The vertical magenta and green lines show the boundary giving the different
shipping dates. The magenta lines show the shipping dates are different by more than
three months.
of measurements. The high voltage was turned off during changing crystals or wrapping materials. To
reduce the time for changing crystals or wrapping materials, two layers of a black box were used. Fig. 4
shows the experimental setup for the measurement of the light output and longitudinal uniformity Leadblocks with nine apertures with a diameter of 3 mm are placed to determine the distance of the 137Cs
source irradiation from the PMT window.
We measured the energy spectra of the output signals from the BGO crystals in response to γ rays
with a CAMAC-based data taking system. The anode signal from the PMT was split into two signals.
One was distributed to a charge-integration ADC module, Technoland C-QV715, and its gate width was
set to 2 µs. The other was used to form a trigger for the data acquisition system and to generate thegate for the ADC module. The decay time of BGO scintillator is rather long, and the output signal does
not form a single pulse in response to a single γ ray from 137 Cs. Thus, the width of the signal for thetrigger was set to 2 µs. The energy was given by a raw ADC and pedestal values, where the pedestal inNon uniformity (%)

85

10
5
0
-5
-10
10
5
0
-5
-10
10
5
0
-5
-10
10
5
0
-5
-10
10
5
0
-5
-10
10
5
0
-5
-10

0

10

12F

11F

10F

09F

08F

07F

06F

05F

04F

03F

02F

01F

00F

00B

01B

02B

03B

04B

05B

06B

07B

08B

20 0

0

10

20 0

10

20

10
20
Distance from PMT (mm)Fig.3. Uniformity U as a function of the distance from the PMT window (measured at NIIC).
The U s for 60 crystals are plotted in each panel corresponding to the polar angle number.
The red boxes show the average of the 60 crystals. The green triangles show U for the
prototype polished crystals scaled by 1/3 [10] (namely actual U ranges from −30% to+30% fro 12F and 00F prototype polished crystals).
each energy spectrum was measured with a 1-kHz clock trigger. Background events were also measured
without the 137 Cs source to enable background subtraction. The energy spectrum in response to the γrays from the 137 Cs source was deduced by subtracting the measured spectrum without the source fromthat with the source. Fig. 5 shows the typical energy spectra in response to the rays from 137 Cs. The
decrease of light output was observed for the polished 00F crystal for short distances from the PMT
window when the crystals were wrapped with Al foil.
The light output varies according to the temperature in the black box due to the change of the light
output of BGO scintillator (−0.9%/K) [12] and due to the change of the quantum efficiency of the bialkali
surface of the PMT used (−0.4%/K) [13]. The decrease of the light output −1.3%/K was expected for thismeasurement. Thus the measured light output LT was corrected using the temperature T as
L = LT {1 − 0.013 (20◦ C − T )}

(2)

86
200
~90

temparature
semsorReflector

Crystalhight : 220
width :
12F 26.2- 00F 43.8

137Cs

630
25
600
Pb
H6410
RD4129
~ 410
310
260

Pb

Pb

~ 160

Fig.4. Experimental setup for the measurement of the light output and longitudinal uniformity.
The left panel shows the schematic view of the setup, and the right panels shows thephotograph. Lead blocks with nine apertures with a diameter of 3 mm are placed todetermine the distance of the 137Cs source irradiation from the PMT window.
so that L stands for the light output at 20◦ C. Fig. 6 shows the light outputs for the different crystals
with different wrapping materials.
The centroid µ corresponding to the photoelectric peak was obtained by fitting a Gaussian function
to the peak. The fitting process was repeated several times in the region [µ − 0.8σ, µ + 2σ), where σdenotes the width of the peak. Fig. 7 shows the light output as a function of the source distance fromthe PMT window. The light output depends on the distance when the crystals are wrapped with Al foil.
When the crystals are wrapped with a ESR sheet, the light output is almost constant for all the crystals.
The |U | value reaches 13.0% for the crystals wrapped with Al foil. In the case of wrapping the crystals
with ESR and Tyvek, the maximum U s are 5.3% and 7.1%, respectively. The standard deviations of U s
are 1.5%, 2.2%, and 3.9% for ESR, Tyvek paper, and Al foil sheets, respectively.
The stability of the gain according to the environment was checked by measuring the light output forthe prototype 00F crystal wrapped with a ESR sheet for every series of the measurements. The variationof the light output for the prototype 00F crystal with ESR is 3.1% for the peak-to-peak difference. The
details of the analysis are described elsewhere [14].

87

300

10 mm
o
(20.9 C)35 mm
o(20.9 C)60 mm
o(20.8 C)85 mm
o(20.7 C)

110 mmo(20.7 C)

135 mmo(20.7 C)

160 mmo(20.7 C)

185 mmo(20.7 C)

210 mmo(20.7 C)

200
100

Counts / 8 channels

0
300
200
100
0
300
200
100
0

0

500

1000

1500

0

500

1000

1500

ADC (channel)

0

500

1000

1500

Fig.5. Typical energy spectra of the prototype etched 00F BGO crystal (Al foil) for different
source distances from the PMT window (measured at ELPH). The source distance is described in each panel together with a temperature in the black box. Each energy spectrum (red) is deduced by subtracting the measured spectrum without 137 Cs (black) fromthat with 137 Cs (blue). The solid curves show the fitted Gaussian function for peaks corresponding to the photoelectric effect. The vertical green lines represent the pedestal
position corresponding to an energy of 0.

ESR

Average light ouput (a.u.)

3000

Tyvek

Al

2500
2000
1500
1000
500
0

0

2

4

6

8

10 12 14
Ring number

16

18

20

22

Fig.6. Light outputs for the different crystals with different wrapping materials (measured at
ELPH). The red circles, green boxes, and blue triangles show the light output for thewrapping materials of ESR, Tyvek, and Al foil. The measurements for the 00B (14) crystal
is omitted since the shape of the 00F (13) crystal is the same as that of the 00B (14)crystal.

88
20
10

12F

11F

10F

09F

08F

07F

06F

05F

04F

03F

02F

01F

00F

01B

02B

03B

04B

05B

06B

07B

08B

0
-10
-20
20
10
0
-10
-20
20
10
0

Unifromity U (%)

-10
-20
20
10
0
-10
-20
20
10
0
-10
-20
20
10
0
-10
-20
20
10
0
-10
-20

0

50

100

150

200 0

50
100
150
200 0
Distance from PMT (mm)

50

100

150

200

Fig.7. Light output as a function of the source distance from the PMT window. The crystal
number is described in each panel (measured at ELPH). The red circles, green boxes,and blue triangles show the light output for the wrapping materials of ESR, Tyvek, andAl foil. The errors represent the widths of the peaks corresponding to the photoelectriceffect.

89§ 4. Summary

An electromagnetic calorimeter, called BGOegg, consisting of 1,320 BGO crystals was constructed

at ELPH. All the crystals were manufactured at the Nikolaev Institute of Inorganic Chemistry (NIIC)
in Novosibirsk, Russia. The relative light output and longitudinal uniformity for the BGO crystals
were measured at ELPH for three wrapping materials, Vikuity Enhanced Speculator Reflector from 3M
company, DuPoint Tyvek 1082D paper, and Al foil. An excellent light output and longitudinal uniformity
has been obtained for the crystals wrapped with ESR.

Acknowledgments
This work was supported in part by Grants-in-Aid for Specially Promoted Research (19002003), for
Scientific Research (A) (24244022), and for Scientific Research (C) (26400287).

References[1]

T. Ishikawa et al.: Proceedings of the 10th International Workshop on the Physics of Excited Nucleons (NSTAR2015), JPS Conference Proceedings 10 (2016) 031001;
T. Ishikawa: Proceedings of the XV International Conference on Hadron Spectroscopy-Hadron2013, PoS (Hadron 2013) 095;
T. Ishikawa et al.: Proceedings of the 20th International IUPAP Conference on Few-Body Problemsin Physics, Few Body Systems 54 (2013) 1047.

[2]

T. Ishikawa et al.: Nuclear Instruments and Methods in Physics Research Section A 622, 1(2010).

[3]

T. Ishikawa et al.: Nuclear Instruments and Methods in Physics Research Section A 811, 124(2016).

[4]

F. Hinode et al.: Proceedings of 2005 Particle Accelerator Conference (2005) 2458.

[5]

T. Ishikawa et al.: Nuclear Instruments and Methods in Physics Research Section A (2016),
http://dx.doi.org/10.1016/j.nima.2016.06.054.

[6]

N. Muramatsu et al.: Nuclear Instruments and Methods in Physics Research Section A 737, 184(2014).

[7][8]

LEPS website: ⟨http://www.rcnp.osaka-u.ac.jp/Divisions/np1-b/⟩.

H. Nagahiro, S. Hirenzaki: Physical Review Letters 94 232503 (2005);
H. Nagahiro et al.: Physical Review C 87, 045201 (2013).

[9]

D. Jido et al.: Nuclear Physics A 914, 354 (2013); and references therein.

[10] T. Ishikawa et al.: ELPH Annual Report 1, 61 (2012).
[11] T. Ishikawa et al.: Testing a prototype BGO calorimeter by using 100-800 MeV positron beams,
submitted to Nuclear Instruments and Methods in Physics Research Section A.
[12] J. Beringer et al. (Particle Data Group): Physical Review D 86, 010001 (2012).
[13] Hamamatsu Photonics, Photomultiplier Tube, 3rd Ed., 2005.

90[14] R. Yamazaki and T. Ishikawa: Internal GeV-γ analysis note HD No. 405B (2016);
R. Yamazaki and T. Ishikawa: Internal GeV-γ analysis note HD No. 406B (2016).

ELPH Annual Report, Tohoku University (2015)91

The status of SPring-8 LEPS2/BGOegg experiments
Norihito Muramatsu1 , Jung Keun Ahn13 , Wen-Chen Chang4 , Jia-Ye Chen5 ,Schin Daté3 , Toshiyuki Gogami2 , Hiroya Goto2 , Hirotomo Hamano2 ,Toshikazu Hashimoto6 , Qing Hua He1 , Kenneth Hicks7 , Toshihiko Hiraiwa2 ,Yuki Honda1 , Tomoaki Hotta2 , Hiroyuki Ikuno2 , Yosuke Inoue1 ,Takatsugu Ishikawa1 , Igal Jaegle8 , Yuuto Kasamatsu2 ,Hitoshi Katsuragawa2 , Satoshi Kido1 , Hideki Kohri2 , Yukiyoshi Kon2 ,Shinichi Masumoto9 , Yuji Matsumura1 , Katsumasa Miki12 , Manabu Miyabe1 ,Keigo Mizutani6 , Taiki Nakamura12 , Takashi Nakano2 , Masayuki Niiyama6 ,Yuki Nozawa6 , Yuji Ohashi3 , Haruo Ohkuma3 , Hiroaki Ohnishi10,2 ,Takeshi Ohta2 , Masaya Oka2 , Kyoichiro Ozawa11 , Mizuki Sasagawa1 ,Takuya Shibukawa9 , Hajime Shimizu1 , Ken’ichiro Shiraishi1 ,Yorihito Sugaya2 , Mizuki Sumihama12 , Shinsuke Suzuki3 , Shintaro Tanaka2 ,Atsushi Tokiyasu2 , Natsuki Tomida6 , Nam Tran2 , Yusuke Tsuchikawa1 ,Hirohito Yamazaki1 , Ryuji Yamazaki1 , Yuka Yanai2 , Tetsuhiko Yorita2 ,and Masaru 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

National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
67Institute of Physics, Academia Sinica, Taipei 11529, Taiwan

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

Department of Physics and Astronomy, Ohio University, Athens, OH 45701, USA
89University of Hawaii at Manoa, Honolulu, HI 96822, USA

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 Education, Gifu University, Gifu 501-1193, Japan

Department of Physics, Korea University, Seoul 02841, Republic of Korea§ 1. Introduction

The physics data-taking at the BGOegg experiments has started from 2014 April at the SPring-

8 LEPS2 beamline (BL31LEP). As one of the main goals, we search for the η ′ meson-bound nuclei,
which is expected as a result of the mass reduction at the nuclear density. The theories based on the
Nambu-Jona-Lasinio (NJL) model [1] and the linear sigma model [2] predict the 80–150 MeV mass

92

Fig.1. Setup of the BGOegg experiments. The size of the RPC wall has been decided based on
the bore diameter of E949 solenoid magnet, which will be used at other experiments.
reduction due to the partial restoration of the chiral symmetry breaking and the UA (1) anomaly. The
BGOegg experiment is an ideal setup to improve the very small signal-to-noise ratio in the missing mass
spectrum of the A(γ, p) reaction significantly. We aim to understand the origin of mass.
We also investigate the hadron pictures through the resonances of meson(s)-baryon and mesonmeson systems. For example, the excited baryon resonances are under studies in the s-channel of single
or double meson (η, η ′ , ω, π 0 π 0 , π 0 η, etc) photoproduction from a proton target. The coupling strengths
to the individual final states depend on the resonance properties like quantum numbers, internal quark
flavors, a specific hadron structure, and so on. We measure not only the production cross sections but
also the photon beam asymmetry by using the high linear polarization available at the LEPS2 beamline,
to study the helicity amplitudes including the interferences between resonances.
At the LEPS2 beamline, a 1.3–2.4 GeV tagged photon beam is produced by the backward Compton
scattering of 355 nm ultraviolet laser light from the 7.975 GeV electron beam [3]. The tagged beam intensity was 1.4–2.1 MHz with the simultaneous injection from three or four lasers (8/16/24 W “Paladin”
by Coherent Inc.). The produced photon beam is delivered to the 135 m-downstream experimental building with the final beam spread of about 6.5 mm in σ [4]. Here the nuclear and liquid hydrogen targets
have been exposed to the high intensity photon beam.
Figure 1 shows the setup of the BGOegg experiments. The “egg”-shaped electromagnetic calorimeter surrounds the target in the polar angle range from 24◦ to 144◦ . 1320 Bi4 Ge3 O12 (BGO) crystals of
20 radiation lengths are assembled in the 60 azimuthal sectors and 22 polar angle layers without deadspaces. The energy resolution is 1.3% at 1 GeV [5], providing one of the world’s highest performances.
The BGOegg calorimeter is essential to identify neutral mesons decayig to γs with a good invariant mass
resolution and to detect the nuclear absorption signals of the η ′ -bound state.
Charged particles are recognized in the wide acceptance range by several detectors. The charge ofa BGOegg calorimeter hit is identified by the inner plastic scintillators (IPS) and the cylindrical drift

93
chamber (CDC). The energy loss at IPS is usable for the separation of proton and pion bands in thecorrelation plot with the kinetic energy measured at the BGOegg calorimeter. The forward acceptancehole of the calorimeter is mostly covered by the planar drift chamber (DC) in the polar angle region lessthan 21◦ . The charged particle direction and kinetic energy are useful to reject the backgrounds withextra particles at a kinematic fit.
A forward proton momentum can be measured by the resistive plate chambers (RPC) [6], whose
wall covers the polar angle region less than 7◦ at the 12.5 m downstream of the target for the time-offlight (TOF) measurement. The measured momentum is the key information to calculate the missing
mass spectrum in the meson-bound nuclei search and to perform the photon beam energy calibration
using the meson photoproduction from a proton target.

§ 2. Collected data

Table 2 summarizes the collected physics data in 2014–2015. In the first half of 2014 (2014A), a 20

mm-thick polyethylene (CH2 ) or carbon (ρ=1.73 g/cm3 ) block was alternatively placed as a fixed target
for the initial calibration purpose and the test analysis of the η ′ -bound nuclei search. Since the readinessof RPC was not enough, only ∼30% was usable to calculated the missing mass in the carbon data, whichcorresponds to 4.3 × 1012 tagged photon counts. Therefore, the carbon target data was collected again

in the first half of 2015 (2015A). If we assume the cross section based on the NJL model [1], the nuclear

absorption signals of the η ′ -bound nuclei may be expected at a hundred event level in the 2015A data,
although such an estimation highly depends on the event selection conditions.
In parallel with the 2014A data-taking, the liquid target system was developed with a 40 mm-thickcell made of polyimide films [7]. The liquid hydrogen (LH2 ) target became ready during the latter halfof 2014 (2014B), and the physics data corresponding to 4.2 × 1012 tagged photon counts were collected

after several tests. We took roughly equivalent amouts of two data sets with the vertical and horizontal
polarization beams. The linear polarization vector was controled by the wave plates on lasers in orderto check the possible geometrical effects in the photon beam asymmetry measurement. In the latter
half of 2015 (2015B), we further accumulated the LH2 target data up to the 1.4 times of the 2014B data
especially for the η ′ and double meson photoproduction.
Table 1. Statistics of the data collected at the BGOegg experiments. The integrated number of tagged
photons is evaluated by correcting the tagging detector counts by the trigger dead time. The
numbers in parentheses at 2014A indicate the statistics for the data with RPC. In 2015A, most of
the data was collected with vertical polarization.

Period2014A(Apr.–July)
2014B(Nov.–Feb.)
2015A(Apr.–July)
2015B(Sep.–Dec.)

TargetCarbon/CH2(20 mm-thick)
LH2(40 mm-thick)
Carbon(20 mm-thick)
LH2(40 mm-thick)Integrated number of tagged photons
C: 4.29×1012 (1.31×1012 )CH2 : 2.56×1012 (1.58×1012 )Hori: 2.24×1012
Vert: 2.01×1012
9.77×1012(Vert: 8.97×1012 )Hori: 2.87×1013
Vert: 2.92×1013

94§ 3. Data calibration

There has been large progress in the data calibrations and the development of event reconstruction

codes. The energy scale calibration of 1,320 BGO crystals has been iterated to adjust the 2γ invariant
mass peak of π 0 at the nominal value [8]. This calibration was then refined by taking into account several
corrections about the realistic geometry of crystal and target positions, the energy leak to the outsideof the sensitive volume, and the momentum dependence of π 0 and η masses. As a result, the mass
resolutions of π 0 and η mesons are 7.7 and 21.1 MeV/c2 , respectively, for the 40 mm-thick LH2 target
data. The correctness of the energy scale calibrations is ensured by the 2γ invariant mass spectrum forthe η ′ meson, providing the peak within 0.4% of the nominal mass, as shown in Fig. 2(a). The use of akinematic fit must reduce the background level further. The η ′ meson has been reconstructed also in theπ 0 π 0 η decay mode, as shown in Fig. 2(b). Since the π 0 and η masses are forced to the nominal values,
the invariant mass resolution becomes 8.6 MeV/c2 .
The TOF from the target to RPC is measured relative to the reference time decided by the accelerator radio-frequency (RF) signal with 508.58 MHz. The true electron bunch where the Compton
scattering happens is solved by taking a coincidence with a tagging detector signal. The RPC time resolutions, measured from the e± TOF distributions with the flight length correction depending on the hit
position, have been obtained to be 70–80 psec strip by strip. The TOF value is transformed to β andthen a momentum by assuming the proton mass with an energy loss correction during the flight. The
momentum resolution is about 1% at 2 GeV/c, providing the resolution comparable with the magnetic
spectrometer. Figure 3(a) shows the measured β versus the missing energy when π 0 or η is identified
at the BGOegg calorimeter. A clear proton band, corresponding to the reaction γp → π 0 p/ηp, is seen.

In the case that a slow particle is detected at RPC, the missing mass spectrum with the assumption ofa proton indicates clear meson peaks, as shown in Fig. 3(b), after requiring the transverse momentum
balance with the two photons detected at the BGOegg calorimeter.
Figure 4(a) shows the photon beam energy calibration for the tagging detector. The tagging de-

Fig.2. The η ′ invariant mass spectra for (a) 2γ and (b) π 0 π 0 η decay modes. The 2014B data
is analyzed by requiring the missing mass to be the proton mass and by confirming theangle consistency between the missing momentum and the detected charged particle.

95

Fig.3. (a) Scatter plot of the β measured at RPC versus the missing energy obtained from meson
detection at the BGOegg calorimeter. (b) Missing mass distribution for the proton whose
β was measreud at RPC.

Fig.4. (a) Photon energy predictions as a function of the tagger hit position. The open circles,
the filled circles, and the filled squares indicate the predictions based on BGOegg, RPC,
and Compton edge, respectively. (b) The distribution of the photon energy measured at
the tagging detector, relative to the prediction from a kinematic fit of the γp → π 0 ηpevents in the 2014B LH2 data.
tector hit position was related with the photon energy predictions by three independent methods: (1) akinematic fit to the γp → π 0 π 0 p events, detected at the BGOegg calorimeter, (2) an inverse calculation

to force the missing mass to the nominal meson masses by detecting a forward proton at RPC in the
γp → π 0 p or ηp events, and (3) the adjustment of the Compton edge to the value expected from the laser

wavelength and the electron beam energy. These methods return the tagger energy functions consistent
with each other, after the careful calibrations mentioned above. The final energy function has been determined by taking a weighted mean of them. Figure 4(b) shows the measurement of a photon energy
resolution by a kinematic fit to γp → π 0 ηp events, where the beam energy is treated as a unmeasured

variable. By subtracting the contribution from the BGOegg energy resolution quadratically, the photon
beam energy resolution was estimated to be 12.05±0.74 MeV. This is consistent with the expectationfrom the electron beam emittance.

96

Fig.5. (a) The kinetic energy prediction as a function of the measured BGOegg cluster energy.
The predicted energies are obtained from a kinematic fit to γp → ωp events in the 2014B
LH2 data. The proton from a 1-nucleon absorption is expected to possess a low kinetic
energy around 100 MeV. (b) The BGOegg cluster energy as a function of the energy deposit at IPS. Events with the BGOegg hit at layer 7 are plotted here. The polar angle
dependence of the IPS energy has been actually calibrated.

§ 4. Preliminary analyses

As described in Section 2, we have analyzed the 2014A carbon data with RPC information as a test

sample of the η ′ -bound nuclei search in the reaction of C(γ, p)11
η ′ B. First of all, we studied the event
selection conditions for the 1-nucleon absorption signal, where the η ′ N → ηN conversion is expected to

be dominant [9]. The produced η meson was tagged at the BGOegg calorimeter in the 2γ and 3π 0 decay
modes for the background reduction more than two order of magnitude instead of the signal acceptanceof ∼0.1. The missing mass spectrum of a forward proton at RPC (M MC(γ,p) ) was examined in boththe η-tag and sideband regions with masking the signal region of the missing mass. It turns out thatthe combinatorial background due to the multiple pion production is not significant in the sideband
sample, but that the η-related backgrounds (ηπ production, etc) largely remain only if the η is tagged.
Therefore, we will obtain extra reduction factors by tagging the opposite proton from the ηN conversion.
This proton can be identified from the kinetic energy measurement at the BGOegg calorimeter andthe energy deposit at IPS, as shown in Fig. 5. We will also explore the tagging condition of 2-nucleon
absorption signals, where nearly back-to-back nucleons are expected at the BGOegg calorimeter and
IPS.
The analyses using the LH2 target data are also in progress. The π 0 γ decay mode in the ω photoproduction and the 2γ decay mode in the η and η ′ photoproduction have been focussed especially tomeasure the photon beam asymmetries. While those mesons are measured at the BGOegg calorimeter, an additional charged track is detected at either of the DC or BGOegg calorimeter to restrict its
direction. Figure 6(a) shows the π 0 γ invariant mass distribution after the kinematic fit with the proton
direction. A clear ω peak is seen with a relatively low background level. In the 2014B data, about 33K,
44K, and 1,200 events are counted for the ω, η, and η ′ events, respectively. These statistics will be
increased by the tagger and IPS analysis upgrades, the use of different decay modes, and the further

97

Fig.6. (a) The π 0 γ invariant mass distribution in the 2014B LH2 data. (b) Azimuthal asymmetry
patterns of the ω photoproduction yield for the vertical polarization beam. (c) Same as(b) but for the horizontally polarized photon beam.
analysis of the 2015B data. Figure 6(b) and (c) show the azimuthal asymmetry pattern of the ω photoproduction yield, without binning the energy and polar angle ranges and taking into account the beampolarization degree. In both the vertical and horizontal polarization data, the asymmetry patterns arewell observed with a ∼90◦ phase difference. Such asymmetry patterns have been seen also in the η andη ′ photoproduction.

§ 5. Summary and prospect

The LEPS2/BGOegg collaboration has started the physics data-taking from 2014 April by using

carbon, polyethylene, and liquid hydrogen targets with the 1.3–2.4 GeV photon beam. We have mostly
finised the preparation of the event reconstruction programs and the precise calibrations with goodunderstandings of the detector performance. Good resolutions in the BGOegg energy measurement,
the RPC TOF measurement, and the tagger beam energy measurement will satisfy our physics goals
mentioned above.
On the η ′ -bound nuclei search, we have started the background reduction studies by tagging the
1-nucleon absorption signal of the bound state. Further improvements of the signal-to-noise ratio will beachieved in both 1-nucleon and 2-nucleon absorption modes. We already have 7 times higher statistics inthe 2015A carbon target data, which will enable to examine the existence of the η ′ -bound nuclei for themodels with deep binding energies. In 2016A, we are also accumulating more statistics with the carbon
target.
For the 2014B LH2 target data, we are first measuring the photon beam asymmetries in the ω,η, and η ′ photoproduction. The differential cross sections will be then measured with the systematic
understanding of acceptance and normalization. Additional 2015B data with the 1.4 times statistics is
also available, enabling the analyses for multiple meson photoproduction, K0S photoproduction, etc.

98

References[1]

H. Nagahiro et al., Phys. Rev. C 74, 045203 (2006).

[2]

S. Sakai and D. Jido, Phys. Rev. C 88, 064906 (2013).

[3]

N. Muramatsu et al., Nucl. Instr. Meth. A737, 184 (2014).

[4]

N. Muramatsu, ELPH Report 2044-13 (2013) or arXiv:1307.6411.

[5]

T. Ishikawa et al., ELPH Annual Report Vol.1, 61 (2012).

[6]

N. Tomida et al., Nucl. Instr. Meth. A766 283, (2014).

[7]

N. Muramatsu et al., ELPH Annual Report Vol.5, 106 (2015).

[8]

K.A. Olive et al. (Particle Data Group), Chin. Phys. C 38, 090001 (2014).

[9]

E. Oset et al., Phys. Lett. B 704, 334 (2011).

ELPH Annual Report, Tohoku University (2015)

99

Commissioning of the SCRIT electron scattering facility
with 132Xe target
K. Tsukada1 , K. Adachi3 , A. Enokizono3 , T. Fujita3 , M. Hara2 , M. Hori3 ,T. Hori2 , S. Ichikawa2 , K. Kurita3 , T. Ohnishi2 , T. Suda1 , T. Tamae1 ,M. Togasaki3 , T. Tsuru1 , K. Yamada3 , M. Wakasugi2 , and M. Watanabe2
1

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

RIKEN Nishina Center for Accelerator-Based Science, Wako, 351-0198
3

Department of Physics, Rokkyo University, Tokyo, 171-8501

SCRIT electron scattering facility has been constructed to realize electron scattering experiments
off unstable nuclei. From January 2016, a series of commissioning experiments with 132 Xe target has
been carried out for the electron beam energies of 150, 200, and 300 MeV. By the comparison with theangular distributions and calculations, an information of nuclear shape are extracted . The present
status of analysis are reported here.

§ 1. Introduction

Charge density distribution of atomic nuclei is one of the most important information for the nuclear

structure investigation. Actually, many stable nuclei have been investigated and our understanding of
nuclear structures have been established by electron scattering experiments in the latter half of the20th century. This method, however, could be applied almost only stable nuclei because of the difficulty
to prepare the target material for short-lived unstable nuclei. Recently, it has been revealed that someof nuclei far from the stability valley have exotic structures such as halo, skin, new magic numbers, andmagicity loss, and so on. Many scientific efforts for understanding unstable nuclear structures are being
made over the world. Because of the great advantages of electron scattering for the nuclear structurestudies, actualization of electron scattering off unstable nuclei has been awaited.
We proposed a completely new target-forming technique, namely SCRIT (Self-Confining Radioactive
isotope Ion Target) which made electron scattering off unstable nuclei possible [1]. After the success ofthe feasibility study of the SCRIT system [2, 3], we have developed the SCRIT electron scattering facility
at RIKEN RI Beam Factory, Japan.
In 2015 and 2016, a series of the commissioning of whole facility with using 132 Xe target have been
performed. In this report, the first measurement of charge density distribution of a nucleus with the
SCRIT electron scattering facility is reported.

100§ 2. Experimental apparatus
2.1 overview of the facility

The facility consists of a 150-MeV racetrack microtron (RTM), an electron storage ring (SR2) equippedwith the SCRIT, an electron-beam driven RI separator for SCRIT (ERIS), a cooler buncher system basedon a linear radio-frequency quadruple trap, and a window-frame spectrometer for electron scattering(WiSES). Figure1 shows an overview of the SCRIT electron scattering facility. Details of the electron
accelerators and ERIS can be found elsewhere [4, 5].

Fig.1.

Overview of the SCRIT electron scattering facility.

The electron beam energy were controlled to be 150 MeV, 200 MeV and 300 MeV. The electron beam
currents were typically 250 mA decreasing to 150 mA at the end of a 40-min run.
2.2 Target
For the commissioning experiment, 132 Xe was not provided from the ISOL system of ERIS, but
extracted from the standard xenon gas which was introduced at an entrance branch of the ERIS system.
After the mass separation, pure 132 Xe ions were bunched and delivered into the SCRIT.
The target ions were stored in the SCRIT for a few hundred ms and ejected to refresh the target
quality because the amount of the residual gases also increased due to the ionization and trap by theelectron beam. The SCRIT operation with and without target ions (IonIN/IonOUT) were alternated forthe comparative measurement and the background subtraction. The trapping times were usually set
to be 240 ms which was decided to maximize the ratio between the number of target ions and residual
gases. The interval among the trapping times was fixed to be 10 ms.

101
2.3 Electron spectrometer (WiSES)
Details of the electron spectrometer were explained in the previous report [6]. After the previous
report, we changed the gas for the drift chambers from He+CH4 (50:50) to He+C2 H6 (80:20) in order toimprove the time resolution and keep the multiple scattering effect low at the same time.

§ 3. Run summary

Table 1 shows a run summary for the series of the commissioning with 132 Xe target until April 2016.

The meaning of each term are explained in the caption. Achieved averaged-luminosities are also listed
in the table. Because we started parameter tuning for the accelerator and the ion transportation systemwith 132 Xe ions from January 2016, the luminosity had been continuously increased and exceeded 1×1027[/cm2 /s] at February 2016.
Table 1. Run Summary Table. The irradiation times are corresponding to the total time of IonIN
conditions. The duty is defined as, duty = TIonIN /(TIonIN + TIonOut + 2 ∗ TInterval ).
The luminosities are averaged values evaluated by WiSES assuming a nuclear charge
density distribution.
Ee [MeV]
150
200
300

Date
19-22/Jan
8-10/Feb
6-14/Apr
16-18/Apr

Irradiation time [sec]1.9×104
7.8×103
1.3×105
1.3×104

Trapping time [ms]
990
240
240
240

Duty [%]
49.5
48.0
48.0
48.0

Luminosity [/cm2 /s]
8.7×1026 ± 2.0%
1.1×1027 ± 2.5%
1.1×1027 ± 1.8%
1.4×1027 ± 30%§ 4. Data analysis

Figure 2 shows a vertex point distribution along the beam direction after the background subtrac-

tion. It is clearly shown that the target ions were trapped inside the SCRIT potential. The reason why
there are two peaks is a distortion of the electric potential due to a gap of the SCRIT electrodes. Figure 3 is a reconstructed momentum distribution for Ee=200 MeV data after a 4-th Runge-Kutta analysis
connecting two tracks of FDC and RDC. The background contributions are already subtracted. The analysis procedure is explained in the previous report [6]. The achieved momentum resolution of 3.5×10−3
is a little bit worse than the design value of 2.5×10−3 due to a lack of knowledge of the magnetic field.
Low momentum tail below the elastic peak can be explained by a simulation as shown in Fig. 4. In thesimulation, the radiative tail at the target [9] and the energy deposit at the beryllium plate which is awindow of the SCRIT chamber and 2 mm thick are taken into account.
Figure 5 shows obtained angular distributions for Ee=150, 200, and 300 MeV. The systematic error
are considered to be 5%, which is still a rough estimation. The differential cross sections are calculated by DREPHA code [8] assuming the two-parameters Fermi distribution as a nuclear charge density
distribution,
ρ(r) =

ρ0
1 + exp( r−C
a )

a=

t
.
4 ln 3

102

80
60
40
20
0
−300

Fig.2.

−200

−100

100

200
300
Vz [mm]Reconstructed vertex point distribution for Ee=200 MeV after background subtraction(IonIN - IonOUT).

1200

Exp. Ee=200 [MeV]

103

1000

σ = 0.70 [MeV/c](δp/p ~ 3.5e-03)

800
600

Sim. Ee=200 [MeV]

102
10

400
200
0
150

Fig.3.

0

1

160

170

180

190
200 210220
Momentum [MeV/c]

Reconstructed momentum distribution for Ee=200 MeV after backgroundsubtraction (IonIN - IonOUT).

120

Fig.4.

140

160

180
200
220
Momentum [MeV/c]

Comparison of the low momentum
tails between our data and simulation.

The luminosities are decided by fitting experimental data assuming a nuclear shape to be C=5.646 fm
and t=2.3 fm which are derived from the muonic X-Ray experiment [10]. The calculation seems to well
reproduce the data although the statistics for Ee=300 MeV is poor.
Figure 6 is a contour plot of χ2 distribution for fitting the angular distributions of Ee=150 MeV and
200 MeV data at the same time by changing parameters, C and t. Here, luminosities of both data areused as free parameters. That is, we analyze only the shape of the angular distributions. From Fig. 6,
the most probable point of C and t is derived with error (1σ) which are listed in Table 2 with valuesof the muonic X-Ray. It is found that < r 2 >1/2 and C are consistent each other. Although the errorof t is too large for a precise discussion, note that the muonic X-Ray measurement is insensitive to theparameter t. So, our result is the first data of 132 Xe charge density distribution.
In order to improve the accuracy of both parameters C and t, the absolute value of the luminosity
is necessary. Analysis of the luminosity monitoring system is also being developed and will be used todecide the luminosity with high accuracy soon.

L dσ [(cm-2s-1)(cm2sr-1)]
dΩ

103

102
10

assuming L=8.7e+26 [cm s ]drepha, Ee=200MeV
assuming L=1.1e+27 [cm-2s-1]
drepha, Ee=300MeV-2assuming L=1.4e+27 [cm s-1]

1
10-1
-2

10 0.4

Preliminary
0.6

0.8

4
3.5

q

Preliminary

eff

1.2
[fm-1]

1.5
1

∆χ 2
=5

2.5
2

+10%
∆χ 2
=1

3

Fig.6.

1

Obtained angular distributions for Ee=150, 200, and 300 MeV. Lines are calculationof a DWBA code assuming the two-parameters fermi distribution as a nuclear shape(C=5.646 fm, t=2.3 fm [10]).

t [fm]

Fig.5.

Ee=150MeV
χ2Exp.
/ ndf
ndf
0.74372.932 /// 12
11
9.436
Exp. Ee=200MeV
Prob
0.9961Prob
0.6653
Exp. Ee=300MeV
p0drepha, Ee=150MeV
0.87491.138
0.06309
1.365 ±±0.07433
0.3141
-2 -1

-10

%

5.2

-5%

5.4

5.6

<r 2
> 1/2
=4

+5%

.78

5.8

7[

fm

]

6
C [fm]

χ2 distribution for fitting the angular distributions (150 and 200 MeV) by changing thenuclear shape parameters, C and t. Contour levels represent ∆χ2 = 1 ∼ 5. A black circle
is a minimum χ2 point. A red star is a position decided by the muonic X-Ray experiment.
Black solid lines are contour levels of < r 2 >1/2 = const..

§ 5. Conclusions and future prospects

The SCRIT electron facility has been constructed to realize electron scattering off unstable nuclei

for the first time. The primary goal of this facility is to determine their charge density distributions
by elastic electron scattering. The elastically scattered electrons were successfully identified, and the104

Table 2. Comparison the nuclear shape parameters between muonic X-Ray and our data (preliminary).
< r 2 >1/2 [fm]C [fm]

t [fm]

muonic X-Ray [10]4.787

5.64602.30 (assumed)

this exp.

4.97+0.25−0.24

5.53+0.12−0.13

2.97+0.52−0.56

momentum distributions can be roughly explained by the simulation taking into account the radiative
tail. The angular distributions for Ee=150, 200, and 300 MeV are well reproduced with calculations
assuming a two-parameters Fermi as a nuclear charge density distribution. By changing parameters, C
and t, of the two-parameters Fermi, the charge radius and diffuseness can be extracted independently.
Following this successful experiments, the electron scattering experiment with series of the Xe
isotopes and 132 Sn trapped by the SCRIT system will be performed this year.

Acknowledgment
This work is supported by Grants-in-Aid for Scientific Research (S) (Grands No. 22224004) from
JSPS.

References[1]

M. Wakasugi et al.: Nucl. Instr. and Meth. A 532 (2004) 216.

[2]

M. Wakasugi et al.: Phys. Rev. Lett. 100 (2008) 164801.

[3]

T. Suda et al.: Phys. Rev. Lett. 102 (2009) 102501.

[4]

T. Suda et al.: ELPH Annual Report 2011-2013 Vol. 2, Tohoku University, 201 (2013).

[5]

T. Ohnishi et al.: Nucl. Instr. and Meth. B 317 (2013) 357.

[6]

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

[7]

T. Tamae et al.: ELPH Annual Report 2011-2013 Vol. 2, Tohoku University, 1 (2013).

[8]

B. Drepher, DREPHA: a phase-shift calculation code for elastic electron scattering, communicatedby J. Friedrich.

[9]J. Friedrich: Nucl. Instr. Meth. 129 (1975) 505.

[10] H. de Vries, W. de Jager, and C. de Vries: Atomic Data and Nuclear Data Tables 36 (495-536) 1987

ELPH Annual Report, Tohoku University (2015)

105(ELPH Experiment : #2778)

Production of K-42,43 radioactive tracer
H. Kikunaga1 , K. Tsukada1 , and T. Suda1
1

Research Center for Electron Photon Science, Tohoku University, Sendai, 980-8578

Photonuclear reaction yields of nat Ca(γ,X)43 K have been measured by comparing with nat Ni(γ,xn)57 Ni
reaction yield. The separation method to isolate carrier-free 43 K isotopes from the Ca target material byusing precipitation method and extraction chromatography has been described.

§ 1. Introduction

Potassium is an essential element for all animal and plant growth. Understanding the behavior ofpotassium in biosphere is important on the various fields such as biological sciences. The radioactive
tracer technique has been widely recognized as a powerful tool for behavior analysis of elements. The
isotopes 42 K (T1/2 = 12.4 h) and43 K (T1/2 = 22.2 h) have a potential as radioactive tracers because of theirsuitable half-lives. In this work, these potassium isotopes were produced in the photonuclear reactionnatCa(γ,X)42,43 K and were prepared as a carrier-free tracer.

§ 2. Experimental

A target stack containing about a 200 mg of CaO pellet and a Ni monitor foil with thickness of 10µm was enclosed in a quartz tube for irradiation with bremsstrahlung. The irradiation was carried out
with the electron linear accelerator at Tohoku University. The accelerator was operated at an electronenergy from 20, 30, 40, and 50 MeV with a mean current around 0.1 mA. The enclosed target was placedin the back of a platinum converter and cooled with running tap water during the 10 min irradiation forthe yield measurements and 1 hour irradiation for the tracer production. The separation procedure forcarrier-free 43 K tracer is shown in Fig. 1. About 20 mL of H2 O was added to the irradiated CaO, andthen 0.5 M (mol/dm3 ) oxalic acid was added dropwise until the pH value was close to 7. The resulting
precipitation, CaC2 O2 , was aged under heating for 20 min. After centrifugation, the supernatant wasdried up on a glass beaker. To the residue was added a mixture of 13 M HNO3 and 35% H2 O2 , and thesolution was heated on a hot-plate to decompose the oxalic acid and oxalates. The potassium isotopes
was adjusted to an 0.001 M HNO3 solution and passed through an extraction chromatographic resin
column (Eichrom, Ln resin, 1 mL) to adsorb completely the calcium isotopes. The irradiated targets
and the 43 K solutions after the chemical separation were subject to γ-spectrometry to determine thephotonuclear reaction yields and the chemical yields, respectively.

106

irradiated CaO

200 mgoxalic acidsupernatantconc. HNO3
H2O2

precipitate(CaC2O4)(decomposition of oxalic acid)

0.001 M HNO3
extraction chromatography
42,43K tracer(Chemical yield 70-90%)
Fig.1. Chemical procedure for the preparation of carrier-free 43 K tracer§ 3. Results

The obtained nat Ca(γ,X)43 K yields are shown in Fig. 2. These photonuclear reaction yields were

determined by comparing with nat Ni(γ,xn)57 Ni reaction yield reported in the ELPH annual report(2014) [1], 1.97(6) × 103 Bq/mg/µA/h for 50 MeV, 1.23(4) × 103 Bq/mg/µA/h for 40 MeV, 6.00(17) ×

102 Bq/mg/µA/h for 30 MeV, and 1.04(3) × 102 Bq/mg/µA/h for 20 MeV. Based on the reaction yields, 1

MBq of 43 K isotope was produced in a 200 mg of a nat KCaO target irradiated for 1 hour at the ELPH

linear accelerator. A typical γ-ray spectrum for the 42,43 K tracer after the chemical purification is shownin the Fig. 3. Only the γ-peaks of K isotopes are observed in Fig. 3 although those of 47 Ca were clearlyseen in the spectrum before the chemical separation. The chemical yields were in the range of 70% to90%. A 43 K tracer will be distributed through a KAKENHI research project, the Grant-in-Aid for Scientific Research on Innovative Areas-Platforms for Advanced Technologies and Research Resources forms
a resource and technical support platform for research “Supply Platform of Short-lived Radioisotopes for
Fundamental Research”, from the latter half of 2016.

References[1]

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

107

K

43

K

Fig.2. Photonuclear reaction yields of nat Ca(γ,X)43 K reaction

K

K
43

K 43

42

K

104

K

43

K

K

43

103

K

40

43

102

43

Counts / channel

43

K

43

105

101
100

0

500

1000
Energy / keV

1500

Fig.3. An example of a γ-ray spectrum of K tracer solution.

2000

108

ELPH Annual Report, Tohoku University (2015)(ELPH Experiment : #2804)

土壌試料中の放射性ストロンチウムの迅速化学分離法の検討
遠藤勇 1 , 大浦泰嗣 2
1 首都大学東京都市教養学部理工学系化学コース （192-0397 東京都八王子市南大沢 1-1)
2 首都大学東京大学院理工学研究科分子物質化学専攻 （192-0397 東京都八王子市南大沢 1-1)

Rapid Chemical Separation Method of Radioactive
Strontium in Soil Samples
Isamu Endo1 and Yasuji Oura2
1

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

2

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

Chemical separation procedure for radioactive Sr in soil samples was developed using a solid extraction method. Strontium was separated quantitatively from acid leachate treating a soil by a batchprocedure without any preconcentrations. Chemical yields of Sr were dependent on a volume of leachate
and an amount of extraction resin, and were roughly guessed based on the distribution ratio. A processing time of chemical separation procedure for Sr in a soil was shortened rather than a traditional
method.

§ 1 . はじめに
2011 年の福島原発事故により，環境中におびただしい量の放射性物質が放出された．事故当初より，国内各地で，事故により放出された 131 I, 137 Cs などγ線を放出する放射性核種については，様々な試料に対して，その濃度が測定されている．一方，γ線を放出しない純β放射体については，その定量には化学分離操作が必須であるため，γ線放出核種に比べて，その濃度の報告は限られている．純β放射体の代表的な核種である 90 Sr の定量には，文部科学省の「放射性ストロンチウム分析法」[1]に準拠した化学分離法が採用されることが多いが，この方法は，沈殿法やイオン交換法などを駆使した非常に煩雑で時間のかかる方法である．そのため，簡便で迅速な化学分離法が望まれている．そこで，最近，様々な分野で急速に広まっている固相抽出法を利用した簡便で迅速に 90 Sr を分離可能な方法を検討する．とくに，将来に同様な事故が不幸にして起こった時を想定し，緊急時の迅速な土壌からの放射性ストロンチウムの分離法を放射性トレーサを利用して検討した．

109§ 2 . 実験方法
2.1 放射性トレーサ製造
ストロンチウムの化学的挙動は 85 Sr(半減期 65 日) トレーサを用いて調べた．塩化ストロンチウムを Al
箔で包み，直径 10 mm のペレットとし，石英管に封入後，最大エネルギー 50 MeV の制動放射線で，4 時間照射した．これを首都大学東京 RI 研究施設にて水に溶解し，トレーサ溶液とした．このトレーサ溶液には，副反応により生成した 83 Rb(半減期 86 日) も含まれていた．Rb は Cs の同族元素であるため，これを利用して Rb の化学的挙動も調べ，放射性 Cs と分離できるかを検討した．
土壌試料には 40 K や，ウラン壊変系列，トリウム壊変系列の天然放射性核種が含まれているため，Sr を正確に定量するには，これらの核種を十分に除去する必要がある．壊変系列の多くの核種はその半減期が短いため，たとえ Sr フラクションに混入しても，しばらく放置すれば十分に減衰する．しかし，210 Pb は半
減期が 22 年と長いため，Sr と分離する必要がある．そこで，203 Pb(半減期 2.2 日) トレーサを用いて，鉛がストロンチウムと十分分離されるか調べた．Al 箔で包んだペレット状の酸化鉛と塩化ストロンチウムを最大エネルギー 30 MeV の制動放射線で，30 分間照射した．照射後，酸化鉛は 4 mol/L HCl に溶解したが，溶け残りが生じたため，上澄み液のみ利用した．そのため，トレーサ実験での鉛担体量が不明である．
塩化ストロンチウムは，1 mL の 8 mol/L 硝酸に溶解した．85 Sr は十分生成しなかったので，87m Sr(半減期 2.8 時間) を利用した．

2.2 トレーサ実験
約 10 g の土壌に濃硝酸あるいは 8 mol/L 硝酸を 30 mL 〜 50 mL を加え，ホットプレート上で数時間加熱し，吸引ろ過した．このろ液を酸溶出液と呼ぶ．これまでに，酸溶出液から Sr を沈殿法により予備濃縮後，固相抽出法により精製する方法を試みていたが，安定した化学収率を得ることができなかった．そこで，予備濃縮せずに，酸溶出液から直接固相抽出法により Sr を分離することを試みた．硝酸水溶液，あるいは土壌の酸溶出液に，85 Sr トレーサ溶液を 100 μ L (Sr 担体約 1 mg を含む) と，固相抽出樹脂 (Sr レジン，Eichrom 社) を 0.5 g または 1 g を加え，1 時間撹拌した (バッチ法)．撹拌後，カラムに移し，レジンと抽出液を分離した．この Sr レジンカラムに，8 mol/L 硝酸を流した後，0.01 mol/L 硝酸で Sr を溶離した (カラム法)．適宜，溶液を Ge 半導体検出器で測定し，Sr の挙動を追った．

§ 3 . 結果と考察
8 mol/L 硝酸に調製した荒木田土の酸溶出液 70 mL に Sr レジンを 1 g 加えて約 1 時間撹拌したところ，
52 %の Sr が Sr レジンに吸着し，Rb は吸着されなかった．また，参照実験として 8 mol/L 硝酸でも同様のバッチ実験をおこなったところ，60 %の Sr が吸着し，8 mol/L 硝酸での分配比は 105 mL/g であった．
酸溶出液から直接 Sr レジンに Sr を吸着させることができ，その吸着率は参照実験よりもわすがに小さいだ
けであることがわかった．カラム法により，Sr レジンに吸着した Sr をほぼ 100 %溶離することができたので，酸溶出液からのバッチ法よる Sr の吸着にひきつづき，カラム法による Sr の溶離を行えば，Sr の化学収率をバッチ法での実験条件から分配比で計算される吸着率として予測することができる．事故時の迅速な測定という状況においては，化学収率を実測する前に，おおよその定量値を得ることができることは大きな利点であるといえる．
土壌の酸溶出液は，一般に黄色から褐色をしており，鉄が多く含まれていると推察できる．これまでに，

110

60 g の黒土を濃硝酸 50mL 中で 3 時間加熱したところ，414 mg の鉄が溶出されたことを得た．土の種類
により，溶出される鉄の量は変化すると考えられるので，鉄が Sr の吸着を妨害しないか調べた．Fe 濃度が0.003, 0.007, 0.01, 0.03 g/mL である 8 mol/L 硝酸溶液と鉄を含まない 8 mol/L 硝酸溶液での Sr 吸着率を調べたところ，いずれも約 30 % 〜 40 %であり，吸着率は鉄濃度に依存しないことがわかった．ただし，分配比から計算される吸着率のおよそ 1/2 であり，現在のところ，その低くなった原因は不明である．また，Rb はいずれの条件でも Sr レジンに吸着しなかったため，土壌中の 40 K や放射性 Cs と十分分離できると考えられる．
天然放射性核種 210 Pb が Sr フラクションに混入すると，Sr 定量値を過剰評価してしまう．8 mol/L 硝酸と 0.01 mol/L 硝酸での Pb の Sr レジンへの分配比はそれぞれ約 500 mL/g と約 100 mL/g であるため，

Pb は Sr レジンに吸着したままで，ほとんど溶離しないと推測される．そこで，203 Pb トレーサを用いて，Sr フラクションへの Pb の混入率を調べた．なお，Sr は 87m Sr トレーサをもちいた．25 mL の酸溶出液に 0.5 g の Sr レジンを加えて分離を行ったところ，Sr と Pb の Sr レジンへの吸着率はそれぞれ 54 %と 89%であった．カラム法で溶離を行った Sr フラクション ( 0.01 mol/L 硝酸 3mL で 3 回．それぞれ第 1，第2，第 3 サブフラクションと呼ぶ) における Sr の化学収率は 30 %で，8 %の Pb が混入していた．Sr は第1 サブフラクションで Sr フラクションでの 94 %溶離されたが，Pb は第 3 サブフラクションでもっとも多く (Sr フラクションの 63 %) 溶離された．溶離液量を 6 mL とすることで，Pb の混入率を減少することができる．Pb が混入した Sr フラクションの Sr を鉄共沈法で精製を試みたところ，203 Pb/87m Sr 計数率比は0.16 %から 0.07 %以下に減少し，鉄共沈法により精製可能であることを確認した．
土壌試料は有機物を含むことが多いが，一般に，有機物があると取り扱いが難しく，また，化学分離を妨害する．放射性ストロンチウム分析法 [1]では，あらかじめ，土壌試料 100 g を 500 ℃で 5 時間加熱することにより，有機物を分解除去するように定められている．この 5 時間を短縮するために，有機物を除去していない黒土 10 g を酸溶出し，Sr レジンによる分離を試みた．Sr レジンへの Sr の吸着率は酸溶出液の有機物濃度に依存しなかったが，有機物濃度が高いほど，Sr レジンからの溶離率は低下した．また，酸溶出液
は黒褐色であり，Sr レジンから溶離した Sr フラクションも着色したため，これは液体シンチレーション検出器による測定には不適切である．Sr フラクションに硝酸を加え加熱してみたが，完全に脱色することは不可能であった．また，酸溶出液に過酸化酸素水を添加して加熱したり，あるいは有機溶媒抽出による脱色を試みたが，これも不可能であった．そこで，20 g 〜 50 g の土壌試料で必要な加熱時間を土壌の色の変化
で定性的に検討したところ，500 ℃で 2 時間加熱すれば，有機物を十分に分解除去できることがわかった．
なお，土壌の加熱前後での質量変化率は，0.5 時間から 5 時間の間では，加熱時間に依存せず，約 47 %であった．少量の有機物が残る場合もあるが，色から判断すると，これは Sr レジンに吸着したままで，Sr フ
ラクションには混入しないようである．

§4 . ま と め
土壌試料の酸溶出液から Sr を粗分離することなく，直接，Sr レジンを用いた固相抽出法で Sr の分離を試みた．バッチ法で行うと溶出液のマトリックスに影響されず，およそ分配比で計算される吸着率で Sr が吸着した．化学収率を実測する前に，定量値を見積もることが可能である．10 g の土壌試料ならば，有機物の加熱除去をふくめて，半日あれば十分に Sr を化学分離できる．

111

謝

辞

制動放射線照射では，菊永英寿准教授と塚田暁助教をはじめ，電子光理学研究センタースタッフの方々に大変お世話になりました．この場を借りて深く御礼申し上げます．

参
[1]

考

文部科学省: 放射性ストロンチウム分析法 (2003) .

文

献

112

ELPH Annual Report, Tohoku University (2015)(ELPH Experiment : #2805)

Study on Metallofullerene Encapsulating Artificial Radio
Element of Promethium
K. Akiyama and S. Miyauchi
Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1
Minami-Ohsawa, Hachioji, Tokyo 192-0397
In this study, we tried to separate trace amount of Pm from large amount of Sm for the detailed Pm
metallofullerene study by cation exchange chromatography. The optimal condition of Pm/Sm separationis the conditioning by 1 M NH4 Cl, 0.2 M HIBA with pH=3.79 as an eluent, and flow rate of 0.5 mL/min.
The Rs value of Pm and Sm separation in this condition is found to be 1.46. This value is applicable forthe actual separation of Pm tracer from large amount of Sm.

§ 1. Introduction

Endohedral metallofullerenes (EMFs) are known as a clathrate compound and are attracting in-terest of the expectation for the potential application brought from their unique physical and chemical
properties. The large number of studies about the EMFs have been reported, so far. Especially for the
EMFs of lanthanide, it has been studied for a variety of encapsulated elements from the dawn of metallofullerene research. However, only metallofullerene of promethium (Pm) has been still missing [1]. It
is well known that Pm is one of the artificial elements belonging to lanthanide elements and do not haveany naturally occurred stable isotope. The chemical property of Pm is considered to be almost same as
those of other neighboring lanthanides, actually most stable oxidation state in water is +3 similar toneighboring element of Nd. In general, Pm is produced from processing nuclear fuel and neutron irradiation of Nd in High Flux Isotope Reactor. However, 143 Pm produced by these methods is not suitable
for the metallofullerene research because of their small γ-ray emission rate and their long half life.
Previously, we reported the production of Pm metallofullerenes using 143 Pm produced by photon
activation of natural samarium and their properties such as oxidation state of Pm in fullerene cage[2]. Though the oxidation state of Pm in fullerene cage and main species of Pm metallofullerenes
were clarified, there are some problems to investigate detailed information about the properties of Pm
metallofullerenes. One of these problems is low activity ratio of 143 Pm in irradiated Sm targets. In theprevious work, Pm metallofullerenes were produced by arc discharge method using porous carbon rods
including Pm without chemical separation from target material of Sm [2]. To improve the activity ratioof 143 Pm, it is necessary to separate Pm from the taget material.
In this study, we try to separate Pm from large amount of Sm by cation exchange method using
high performance liquid chromatography (HPLC).

113§ 2. Experimental

2.1 Production of Promethium-143
About 1.0 g of Sm oxide were wrapped by Al foil and sealed into quarts tubes. These targets were

irradiated by 50 MeV photon at Research Center for Electron Photon Science in Tohoku University.
Irradiated Sm targets were dissolved to conc. HCl and then evaporated to dryness to make Sm and Pm
to chloride form. Chlorinated target materials were dissolved to 3 mL of 2 M HCl. Accurate 10 µL of 2
M HCl solution was added to 9.990 mL of H2 O for dilution.
2.2 HPLC Separation of 143 Pm from Sm by Cation Exchange
Figure 1 shows the schematic diagram of cation exchange chromatography apparatus used in thiswork. Diluted Pm/Sm solution was loaded into cation exchange column (Inertsil CX, GL Science coltd., size: 4.6 ϕmm×250mm) with 0.5 mL/min of the flow rate. Alpha-hydroxyisobutylic acid (α-HIBA)
solution was used for an eluent. As a post column reagent, 0.2 mM of 4-(2-pyridylazo) resorcinol (PAR)was employed. Eluted components were monitored by UV detector at wavelength of 530 nm. Column
temperature was kept at 50 o C during the experiments. Eluate were collected for every two minutes. γ
ray emitted from these fractions were measured by germanium detector.

Fig.1. Schematic diagram of cation exchange chromatography apparatus used in this work.

§ 3. Results and Discussion

The separation conditions, such as the form of a resin, concentration of an eluent, and pH of asolution, were severely affect to the separation of neighboring lanthanide elements. Before Pm/Sm
separation, we tried to check the peak resolution (Rs) on this column by cold experiment using Nd and
Sm. The peak resolution is simply defined as follows:
Rs = 2(TR2 − TR1 )/(W1 + W2 )Here, TR1 , TR2 , W1 , and W2 indicate chromatographic retention time and peak width (3 sigma) of

114
peak1 and 2, respectively. According to the chromatography theory, the Rs between Pm and Sm must be
greater than 1.0 for the separation of Pm from Sm because more than about 99.9% of Sm can be removed
at this Rs value [3]. To achieve Rs of Sm and Pm beyond 1.0, Rs between Nd and Sm is required to beover 2.0. Table 1 shows the Rs value for each cation exchange condition tested in this work.
Table 1. Rs value of Sm and Pm for cation exchange conditions.
No.

Conditioning

1

1 M NH4 Cl

2

1 M NH4 Cl

31 M NH4 Cl

41 M NH4 Cl

5

1 M NH4 Cl

6

1 M NH4 Cl

SampleEluent10 mg (Sm/Nd=1/1)
pH=4.00
0.5 mg (Sm/Nd=1/1)
pH=4.00
0.5 mg (Sm/Nd=4/1)
0.3 M HIBA pH=3.69
0.1 mg (Sm/Nd=4/1)
0.3 M HIBA pH=3.69
0.1 mg (Sm/Nd=4/1)
0.3 M HIBA pH=3.69
0.2 mg (Sm/Nd=3/1)
dil. HCl

0.3 M HIBA
pH=3.87
0.3 M HIBA
pH=3.87
0.3 M HIBA
pH=3.69
0.3 M HIBA
pH=3.69
0.3 M HIBA
pH=3.69
0.2 M HIBA
pH=3.79

Flow RatemL/min

Rs

0.5

0.86

0.5

2.65

1.0

1.01

1.0

0.95

1.0

1.30

0.5

4.16

From these tested results, we decided to employ the cation exchange condition of batch No. 6 forthe separation of Sm and Pm.
Figure 2 shows a HPLC chromatogram of Pm/Sm separation with above mentioned condition. Solidcircles and open circles indicate radioactivity of 143 Pm and 145 Sm observed in the fractionated samples.
Observed radioactivity in this figure is normalized to the radioactivity observed in the injection sample. Solid lines together with circles were results of peak fitting of the data. For comparison, HPLC
chromatogram of No. 6 were also shown in this figure.
The Rs value of this result is estimated to be 1.46. For the Pm separation, if the peak fractions
from 23 to 26 min. are collected in this chromatogram, the residual Sm amount would be estimated to
be about 0.1%. This residual amount would be enough radioactivity ratio of Pm for the detailed study of
Pm metallofullerenes.

Conclusion
In conclusion, we could find optimal condition of the separation of Pm and Sm and successfully
separated Pm from large amount of Sm by cation exchange chromatography. Estimated residual amountof Sm is found to be about 0.1%.

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 Professor Hidetoshi Kikunaga
and Doctor Kyo Tsukada for helping us in the sample irradiation.

115

Fig.2. HPLC chromatogram of Pm/Sm separation under the condition No.6. Solid circles andopen circles indicate radioactivity of 143 Pm and 145 Sm observed in the fractionated samples. Observed radioactivity in this figure is normalized to the radioactivity observed in
the injection sample.

References[1]

H. Shinohara: Rep. Prog. Phys. 63 (2000) 843.

[2]

K. Akiyama et al.: ELPH Annual Report 5, Tohoku University, 135 (2014).

[3]

J. Cazes and R. P. W. Scott: Chromatography Theory, Marcel Dekker Inc., New York (2002).

116

ELPH Annual Report, Tohoku University (2015)(ELPH Experiment : #2814)

Study of W converter’s thickness of 100Mo(γ,n)99Mo process
Jiaolong Li1 , Mingzhang Lin2 , Liusi Sheng2 , Yuzhi Guo1 , Toshitaka Oka3 ,and Hidetoshi Kikunaga4
1
2

Beijing ZHIBO Bio-Medical Technology Co.,Ltd

The University of Science and Technology of China

3

Institute for Excellence in Higher Education, Tohoku University, Sendai, 980-8576

4

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

We carried out experiments to investigate how the thickness of bremsstrahlung converter target,
tungsten (W) here, affects the yield of 99 Mo from 100 Mo(γ,n)99 Mo process. The photons were generated
through bremsstrahlung when the high energy, 50 MeV, electron beam irradiated the W converters. The
yields of 99 Mo were obtained by measuring the activities of 99 Mo of natural molybdenum targets, whichplaced behind the W converters along the direction of electron beam, using a high purity Ge detector
and a standard radioisotopes source. The thickness of W converters were 3.5, 4.0, 4.5, 5.0, and 5.5 mm,
respectively. The current analysis outcome was presented here.

§ 1. Introduction
99m

Tc having half-life of 6 hours that decays to the much longer lived 99g Tc by emitting a 141 keV

γ-ray and it plays a critical role in the nuclear medicine, see Fig. 1 [1]. It can be bound into a varietyof special molecules that target specific parts of the body when ingested or injected. By detecting the141 KeV γ-rays its location within the body can be pinpointed, which is known as the SPECT (single
photon emission computed tomography) imaging [2]. It is used primarily to locate tumors in the body,monitor cardiac function following heart attacks, map blood flow in the brain and guide surgery. The
information from these studies is used by many medical specialists including radiologists, cardiologists,

Fig.1. Decay of 99 Mo and 99m Tc [1].

117

Fig.2. Schematic diagram of 100 Mo(γ,n)99 Mo.

nephrologists and oncologists to better diagnose and treat patients. It is also used for brain, cerebral
perfusion, liver, bone and bone marrow, blood pool, and pulmonary perfusion imaging etc. [3].
Currently, almost all of the 99m Tc used for radio-pharmacy is produced by milking out from the99

Mo/99m Tc generator where the 99 Mo is held by an alumina chromatographic column. The half-life of99

Mo, 66 hours, is longer than 99m Tc, see Fig. 1. That is better for shipping to radio-pharmacies andhospitals. The dominant produce route for 99 Mo is the fission of high enriched uranium-235 (HEU),
which is of weapons grade, from several aging reactors [2]. The desirable nuclide, 99 Mo, only occupies
6 % among the fission products [4]. That’s to say, it produces lots of reactive waste. Moreover, the HEU
is expensive and restricted by IAEA avoiding the nuclear proliferation.
The planned and unplanned shutdowns of some of the aging reactors have resulted in the supply
interruptions of 99 Mo [5]. And the construction of reactor would be much tough in terms of the cost,safety, licensing, time and complications. That prompted international organizations and several government agencies to step up efforts to find both short and long term alternative solutions to supply
shortages. Recently, the 100 Mo(γ,n)99 Mo process has arisen growing interesting as an promising method
since it provides an alternative, simple, ecological and safe production for produce 99 Mo: On the one
hand, with the development of accelerator technology, the performance and reliability of electron linacs
have been improved. On the other hand, there are many advantages of produce 99 Mo using electron
accelerators, for example less construction cost, much more easily for getting licenses and operating,safer, without U-235, the less radio waste and so on. It is also provides a possibility for producing othermedical radio-nuclides such as 22 Na, 58 Co, 47 Ca supplied from reactors.
In the process of 100 Mo(γ,n), a high-powered electron accelerator would be used to irradiate abremsstrahlung radiation converter. Then the molybdenum target behind the converter along the direction of electron beam was irradiated by the bremsstrahlung photons, and the major reaction 100 Mo(γ,n)99 Mo
happened, see Fig. 2. The thickness of converter target is a key factor to the yield of 99 Mo. In the experiment we had measured the yield of 99 Mo from the irradiated molybdenum targets. And observed how
the thickness of W converter affected on the yield of 99 Mo.

§ 2. Experimental and current status of analysis

In the experiment we investigated how the thickness of bremsstrahlung converter target, tungsten(W) here, affected the yield of 99 Mo from 100 Mo(γ,n)99 Mo process. The yields of 99 Mo were obtained bymeasuring the activities of 99 Mo of natural molybdenum targets using a high purity Ge detector (Ortec

118
34

Activity of Mo-99 (μCi)

33
32
31
30
29
28
27
26
3.0

3.5

4.0

4.5

5.0

5.5

6.0

Thickness of W converter (mm)Fig.3. Measured activity of 99 Mo dependence on the thickness of W converter.
9.20
9.15
9.10
9.05

Integral

9.00
8.95
8.90
8.85
8.80
8.75
8.70
3.2

3.4

3.6

3.8

4.0

4.2

4.4

4.6

4.8

5.0

5.2

5.4

5.6

5.8

Thickness of W converter (mm)Fig.4. Simulation outcome of how W converter thickness affects the yield of 99 Mo.

GEM 55P4-83) and a standard radio-isotopes source (No. 1743-70). The thickness of W converters were
3.5, 4.0, 4.5, 5.0, and 5.5 mm, respectively. The current and energy of the irradiated electron beam was
11 µA and 50 MeV, respectively.
The measured activities of 99 Mo dependence on different W converters were shown in Fig. 3. The
simulation outcome was also presented in Fig. 4. The integral in Fig. 4 resulted from the follow formula.
Integral =∫ Emaxϕ(E)σ(E)dE,

Ethwhere E is the energy of bremsstrahlung photon. Eth is the threshold energy for 100 Mo(γ,n)99 Mo. Emax
is the maximum energy of the bremsstrahlung photons, namely the energy of incident electron. ϕ(E) isthe bremsstrahlung photon flux which is a continuous distribution up to the energy of incident electron
beam. σ(E) is the cross-section of the 100 Mo(γ,n)99 Mo.
As seen from Fig. 3, it seems that the yield of 99 Mo decreases when the W converter thickness

119
increased from 3.5 mm to 5.5 mm. However, the computed outcome, see Fig. 4, indicated that the
optimized thickness of W converter is 4.5 mm at 50 MeV. We are presently designing new experimentand trying to improve the analysis method.

Acknowledgment
The authors would like to thank to the accelerator group providing the stable beam, and all thefacility staffs in the LNS-tohoku for their kind supports.

References[1]

R. Avakian et al., Arm. J. Phys. 6 (2013) 35.

[2]

H. Naik et al., J. Radioanal. Nucl. Chem. 295 (2013) 807.

[3]

R. Crasta et al., J. Radioanal. Nucl. Chem. 290 (2011) 367.

[4]

Medical Isotopes: Report of the Task Force on Alternatives for Medical-Isotope Production, A.
Fong, T. I. Meyer, K. Zala (Eds.), TRIUMF, 2008.

[5]

Non-HEU Production Technologies for Molybdenum-99 and Technetium-99m, IAEA Nuclear Energy Series, NF-T-5.4, 2013.

II. Status ReportELPH Annual Report, Tohoku University (2015)

121

Status of Accelerator Facilities in FY2015
Accelerator groupResearch Center for Electron Photon Science, Tohoku University, Sendai, 982-0826

The electron accelerator complex (high intensity 60 MeV linac, 90 MeV injector linac, 1.3 GeV
booster-storage ring and 50 MeV linac as a test accelerator for coherent THz source) have been welloperated without any significant trouble in FY2015. In this report, machine status and some improvements are presented.

§ 1. Low Energy Linac for RI Production
1.1 Overview of machine operation

A 60 MeV high-power electron linac has been operated and beam-on time was for 176 hours in
FY2015. A major usage for this linac is a mass production of radioactive isotopes (RI), and accelerator
parameters and an irradiation system are optimized for the RI production (Fig.1). Furthermore, beam
damage test for a material physics experiment have also performed using this linac in this year. For RI
productions, linac had operated with beam energy from 20 to 50 MeV. The average current was up to
120 µA with beam repetition of 300 pps. The maximum energy of this linac is 60 MeV. A beam damage
test experiment required as lower average current as possible. Since we have no operation experience
with lowering average current, a timing system was modified for a single pulse beam injecting per asecond. The experiment has done at 50 MeV with the average current of 0.3 µA for 1, 10, and 30 sec. ofirradiation time (Fig.2).

Fig.1.

Beam profiles for RI production. Electron beam
extracted to air (left), and electron beam on φ40mm screen at a converter position prior to theexperiment (right).

Fig.2.

Target scintillator placed atbeam axis for beam damaged
testing of a material physics experiment.

122
1.2 Beam Monitor Replacement
That stable operation of 60 MeV linac with the average current of 120 µA is possible by many
years of assiduous effort. However, the current beam transport optics is not well known yet since there
is only few specification datasheet for quadrupole magnets of beam transport line. The quantificationof beam transport optics is our current objective. We have employed thinner screen and gated digital
cameras to achieve a beam base diagnostics in this year (Fig.3). By employing Quadrupole-Scanning
method, the beam emittance of 60 MeV linac was measured as about 80π mm·mrad. As the result of
this measurement, we found an uncertainty in vertical Twiss parameters across the dispersion section
which is inconsistent with ideal optics, and it will be investigated in next year.

Fig.3.

A screen of 50 µm thickness for an emittance measurement (Left), one of 200 µm thickness for monitoring energy spread at the dispersion section (center), and one of 200 µm
thickness for monitoring beam position at downstream of the dispersion section (right).

1.3 Ion Pump Replacement
Current major concern of 60 MeV Linac is an instability of beamline vacuum condition. An operation is sometime suspended by sudden increase of vacuum pressure. In this year, a few ion pumps in abeam transport have been replaced (Fig.4). We are planning to refurbish the detached ones in 2016 by replacing the pumping elements, and an automation of ion pump baking procedure is under development.
Routinization of ion pump refurbishment is our current objective.
1.4 Interlock Module Replacement
Two 25 MW klystrons feed RF power to eight accelerating structures in 60 MeV linac. As it run several decades, some function is omitted and replaced at each maintenance time or each troubleshooting.
Since components goes out of production, the interlock module for klystron No.1 has replaced in this year
(Fig.5). Replaced module functions as same as the original. Minor change is an employment of thresholdsetting to the overcurrent detector. As additional change, it is mounted on a rail to improve the accessibility for maintenance. Since many control modules goes out of date for the olds with no schematic left,
redesigning module is required to operate accelerator in good shape and to run cost effectively.

123

Fig.4.

Fig.5.

Work for ion pumps replacement.

Replaced interlock module for Klystron No.1.

§ 2. 90 MeV Injector Linac for the 1.3 GeV Booster-storage ring

The injector linac had been stably operated and regularly supplied electron beam for the booster-

storage ring. In the end of FY2015, however, there was a trouble on the thermionic rf gun in the injector
linac. A discharge in a cathode cell of the gun cavity was frequently observed, so that the beam current
extracted from the gun was very unstable. Since we have an experience that a carbon-like material
deposited between the cathode and cavity wall for the CeB6 cathode, which caused the discharge in thecathode cell, we finally decided to replace the cathode to new one. Figure 6 shows a schematic view for
the cathode assembly of rf gun. The operated time of this cathode was about 13 month and a decrease ofemission current had not been observed for this period. Figure 7 shows the detached cathode from the rf
gun. As we expected, the deposition on the cathode was clearly observed. Although more investigationis required to make a definite strategy avoiding this cathode deposition, insufficient vacuum pressure

124might be considered as the reason of the deposition. Therefore an additional ion pump was installed to
improve the vacuum pressure around the cathode.

Fig.6.

Fig.7.

Schematic view for cathode assembly of thermionic rf gun

Detached CeB6 cathode. It was confirmed that the carbon-like material was deposited on
the cathode.

§ 3. 1.3 GeV Booster-storage ring (BST ring)

3.1 Improvement of control system for steering magnets
In order to suppress dynamical COD change in ramping process, it is required to control output

current for steering magnet dynamically. Power supply for the steering magnets originally used in
BST ring is equipped with a pattern memory and can be operated with a sequence mode that controls
the output current as synchronizing with the ramping pattern. However time response for the output
current in this mode is quite slow and limited only to 50 ms. Recently we have introduced a dynamical
control mode for the steering magnet by applying an analog signal to the power supplies. In this system,

125
power supplies are operated as amplifiers (namely power booster mode) and much faster time response
can be realized. Figure 8 shows a configuration of control system for the steering magnet. Analog output
module consists of FPGA and DAC, which are installed in CompactRIO (National Instruments Co.). A
specified pattern data is converted to sequential data and stored in FPGA (Spartan-6 LX45). The stored
data, then, are transferred to DAC (NI9263, 10 V, 16 bit) with each 20 µs clock timing and converted toanalog data synchronized with an external trigger. The originally used power supply (KIKUSUI PBX205) for steering magnet has also power booster mode as well as the sequence mode that can be adopted to
our new system, thus whole system was tested under the actual condition.

Fig.8.

Configuration of former and new control system for steering magnet.

Prior to the beam operation, we confirmed the improvement of the response time of output current.
The power supply was tested under a set value with the much steeper slope of 1 A/ms than nominal
value in specification sheet. Figure 9 shows the comparison of the time response of output current for
the former and new control system, in which it is found that the delay time from the trigger signal isdrastically improved. Furthermore the ramping slope is also improved and almost approaching to alimit of 50 A/s defined by power supply and coil impedance. As the result of this upgrade, the tracking
capability for ramping pattern was much improved and thus beam loss in the acceleration period has
been also reduced.
In order to suppress the COD change in ramping process due to eddy current in the vacuum chamber wall, the dynamical control for the steering magnet was introduced by employing the power booster
operation with CompactRIO system. Combining with effort of realignment work for the whole ring, thisimproved the injection-acceleration efficiency to over 50 %, and the beam current more than 30 mA are
obtained at the top energy by only one macropulse injection with peak current of 40 mA. The ramping

126

Fig.9.

Comparison of output response for former (upper) and new (lower) control system.
(Scales: 100 mA/div, 4 ms/div)

slope of ∼ 600 A/s for dipole magnets in the current operation is still 60 % for the maximum slope definedby power source, so that it should be possible to increase the slope to improve the duty factor for the pat-tern operation. However there is still a problem in power supply for steering magnet which prevents theincrease in ramping slope. It was found that this power supply has a ringing behaviour for the larger
slope of about 10 A/s and which is actually wiggling the beam. Concerning this issue, very recently wehave been trying to replace these to more stable power supplies, and found that, at least, model BWS605 (Takasago Ltd.) is available for the slope more than 100 A/s without the ringing response. Now we arepreparing to replace all power supplies to this model, and then optimization of the orbit control in theramping process will be performed to improve the duty factor and also further reduce the beam loss.

127§ 4. Summary and prospect

In FY2015 the approved beam time have been well consumed as scheduled. The total time of

176 and 1509 hours were operated in this year for high-power linac and BST ring, respectively. Somemaintenance work were also performed, i.e. improvement of monitor system, installation of additional
ion pump for rf gun, etc., which brought more reliable and stable operation for user. As the current
problem for both the high-power linac and BST ring, the improvement of vacuum pressure is quite
important which limits the machine performance. Reinforcement of vacuum system will be conducted in
the coming years.

128

ELPH Annual Report, Tohoku University (2015)

User Support Office Report in FY2015
M. Miyabe on behalfof 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 2015 financial year, we had provided the electron, photon and positron beam without big problems.

§ 1. Introduction

ELPH has three accelerators for Joint Research. Our facility could provide several beams withfollowing 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 93 MeV injector at
the second irradiation lab (For Hadron Physics)• Tagged photon beam at the GeV-γ irradiation room (For Hadron Physics)

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. It could produce radio active source with its high intensity. Both tagged photon beam line was used for Hadron
physics experiments. NKS2 and FOREST experiment have bean held in recent years.

§ 2. Beamtime operated

The total radiation time was 176 hours for the RI linac operation and 1509 hours for the BST

operation, and it was 1686 hours in total. The beam provided time (user beamtime) was 126 and 1474
hours for the RI linac and BST operations, and it was 1600 hours in total. Table 1 summarizes theradiation times, and user beam times in fiscal year 2015.
Many experiments for testing detectors were made by positron beam line. Positron beam was produced by bremsstrahlung photon beams from the synchrotron. Total 50 shift experiments are performed
using this positron beam in this financial year.
A Next generation FOREST experiments is planned by GeV-γ group in ELPH. New bending magnet
will be installed on the downstream of FOREST detectors and it covers the most forward angle. These
new experimental setup enable the zero degree proton detection for the γd → pηn reaction at Eγ ∼ 0.9

GeV. This reaction gives the zero relative momentum between the η and n. This situation will enable todetermine the ηn scattering length. In this financial year, All detectors of FOREST recovered from the129earth quake disaster at 2011 and Tagged photon energy was newly calibrated using the TAGX magnet
and η photo-production threshold measurement (#2761 T. Ishikawa, ELPH, Tohoku University).
Both the two photon beam line (NKS2 and GeV-γ) cannot be stably produced in the lower storage
current and lower electron energy, because of a degree of poor vacuum in BST ring. The machine study
was stil continued to improve this situation during this year.
Two experiments were proposed, and carried out for the undergraduate students. The first one(#2794: T. Ishikawa, ELPH, Tohoku University) is for the third school for giving an opportunity using
an accelerator to young undergraduate students (Y. Sakemi) [1], which was supported by High Energy
Accelerator Research Organization (KEK) for the corporations between Tohoku University and KEK (H.
Tamura). The second one (#2796: M. Miyabe, ELPH, Tohoku University) is for the education of theundergraduate students in ELPH.
Table 1. Radiation times, and user beamtimes in financial year 2015. They are given by the sumof the times that the beam is coming to the beamtime, and that the beam is provided tothe users.
RI Linuac
BST RingMonthradiation (h) user (h) radiation (h) user (h)
April
0
0
79
0
May
9
9
328
346
Jun
26
22
274
266
July
15
5
8
6
August0000September
10
00
October
32
26
92
103
November
26
22
129
156
December
12
10
134
133
January25
16
15
10
February
12
11
177
177
March
17
8
275
275
Sum
176
126
1509
1474

§ 3. ELPH workshops and ELPH seminars

In this fiscal year, ELPH supported two ELPH workshops. The first one is hadron physics (C013:

H. Fujioka, Kyoto University), the second is on an application of the high intense low energy electrons(C014: K. Watabe, CYRIC Tohoku University). Seven ELPH seminars were held in this fiscal year.
Seminars title and talker are listed below.
• M. Ito, CYRIC Tohoku University, ”12 C hoyle state and alpha cluster condensation”• I. Nakagawa, Riken, ”Study for proton spin crisis at the high energy polarized proton collider
experiment”• Steven Karataglidis, Univ. of Johannesburg, ”Mapping the Densities of Exotic Nuclei”• H. Kawai, Chiba University, ”0.1 mm position resolution gamma ray detector”• T. Nakamura, H. Kashima, Hitachi Zosen Corporation, ”Development of radiation measurement
device”

130• T. Sanuki, Tohoku University, ”Towards the realization of ILC”

• T. Mibe, KEK, ”Precise measurement of g-2/EDM with ultra cold muon beam”

References[1]

Y. Sakemi, Web site < http://cycgw1.cyric.tohoku.ac.jp/~sakemi/cyric2015.html >ELPH Annual Report, Tohoku University (2015)

放射線安全管理室報告
放射線安全管理室

Radiation Safety Report 2015
Radiation Safety Office2015 年度（平成 27 年 4 月〜平成 28 年 3 月）
§ 1 . 変更申請
2015 年度の変更承認申請はない。

§ 2 . 個人管理
2.1 放射線業務従事者登録156 人（東北大 72 人、学外 73 人、研究者以外 11 人）
2.2 個人被ばく管理
1 年間の個人被ばく線量 5 mSv 以下 156 人
2.3 教育訓練
定期講習
平成 27 年 6 月 5 日 新規教育 16 人、 再教育 80 人
特別講演の内容：高エネルギー加速器研究機構
特別教授 桝本 和義氏「核理研で学んだこと −加速器利用と放射線安全管理−」
不定期の講習32 回

78 人§ 3 . 自主点検
年 2 回実施

平成 27 年 9 月 28 日、平成 28 年 3 月 17 日

131

132

§ 4 . 製造核種と数量
2015 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とおり。
核種

数量 (kBq)

Au-19670

Cd-1095

Ce-139

520

Co-57

1,180

Cr-51

2,000

Cs-132

50

Cu-64

300

Cu-67

200

Dy-159500

Er-169

500

Ga-68

1,000

Gd-159301

In-114m

20

K-42

200

K-43

1,000

Mo-99

1,000

Na-22

10

Nd-147

2,000

Ni-57

10,000Pb-20330

Pm-143450

Pt-197200

Ru-103300

Sc-44m

500

Sc-47

3,000

Sn-119m

205

Sr-85

1,453

Ta-18210

Tl-202

10

W-185

200

Yb-175

500

Zn-65

201

Zr-89

500

全 33 核種

計 28,415 kBq

III. List of Publication

ELPH Annual Report, Tohoku University (2015)

133

List of Publication (論文リスト) (2015)
Papers Published in Refereed Journals
東北放射光（SLiT-J）計画が目指す光源性能
濱広幸

表面科学，第 36 巻第６号，pp291-296

Positron capture simulation for the ILC electron-driven positron source
Yuji Seimiya, Masao Kuriki, Tohru Takahashi, Tsunehiko Omori, Toshiyuki Okugi, Masanori
Satoh, Jyunji Urakawa and Shigeru Kashiwagi
Progress of Theoretical and Experimental Physics 2015, 103G01
Grid pulser for an electron gun with a thermionic cathode for the high-power operation of a terahertz
free-electron laser
Shoji Suemine, Keigo Kawase, Naoya Sugimoto, Shigeru Kashiwagi, Kazuya Furukawa, Ryukou
Kato, Akinori Irizawa, Masaki Fujimoto, Hiroki Ohsumi, Masaki Yaguchi, Sousuke Funakoshi,
Ryouta Tsutsumi, Kumiko Kubo, Akira Tokuchi, Goro Isoyama
Nuclear Instruments and Methods in Physics Research A 773 (2015) 97-103.
The SCRIT electron scattering facility project at RIKEN RI beam factory
T Ohnishi, A Enokizono, M Hara, T Hori, S Ichikawa, K Kurita, S Matsuo, T Suda, T Tamae,
M Togasaki, K Tsukada, T Tsuru, S Wang, S Yoneyama and M Wakasugi
Phys. Scr. T166 (2015) 014071 (5pp).
Observation of Spin-Dependent Charge Symmetry Breaking in ΛN Interaction: Gamma-Ray Spectroscopyof 4Λ He
T.O. Yamamoto et al.
Phys. Rev. Lett. 115 (2015) 222501, 1-5.
Precise determination of 12
Λ C level structure by γ-ray spectroscopy
Kenji Hosomi et al.
Prog. Theor. Exp. Phys. 2015 (2015) 081D01.
Hypernuclear production cross section in the reaction of 6 Li+12 C at 2 A GeV
C. Rappold et al.
Phys. Lett. B 747 (2015) 129―134.
Comparative analysis of kdp and ktr mutants reveals distinct roles of the potassium transporters in themodel cyanobacteriumSynechocysis sp. PCC6803.
Nanatani, K., Shijuku,T, Takano, Y., Zulkifli, L., Yamazaki, Y., Tominaga, A., Souma, S.,
Onai, K., Morishita, M., Ishiura, M., Hagemann, M., Suzuki, I., Maruyama, H., Arai, F., andUozumi, N.
J.Bacteriol. 197, 676-687 (2015).

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The jasmonate-responsive GTR1 transporter is required for gibberellin-mediated stamen development
in Arabidopsis
Saito, H., Oikawa, T., Hamamoto, S., Ishimaru, Y., Kanamori-Sato, M., Sasaki-Sekimoto, Y.,
Utsumi, T., Chen, J., Kanno, Y., Masuda, S., Kamiya, Y., Seo, M., Uozumi, N., Ueda, M., andOhta, H.
Nature Commun. 6:6095 (2015).
HKT transporters mediate salt stress resistance in plants: from structure and function to the field
Hamamoto, S., Horie, T., Hauser, F., Deinlein, U., Schroeder J.I. and Uozumi, N.
Curr. Opin. Biotechnol. 32, 113120 (2015).
The phytosiderophore efflux transporter TOM2 is involved in metal transport in rice
Nozoye T., Nagasaka S., Kobayashi T., Sato Y., Uozumi N., Nakanishi H. and Nishizawa N.K.
J. Biol. Chem. 290, 27688-99 (2015).
Iron deficiency regulated OsOPT7 is essential for iron homeostasis in rice
Bashir, K., Ishimaru, Y., Itai, R,N,, Senoura, T,., Takahashi, M., An, G., Oikawa, T., Ueda, M.,
Sato, A., Uozumi, N., Nakanishi H., Nishizawa, N.K.
Plant Mol. Biol. 88, 165-76 (2015).
Decontamination Effects of Bark Washing with a High-pressure Washer on Peach [Prunus persica (L.)
Batsch] and Japanese Persimmon (Diospyros kaki Thunb.) Contaminated with Radiocaesium during
Dormancy
Sato, M., Abe, K., Kikunaga, H., Takata, D., Tanoi, K., Ohtsuki, T., Muramatsu, Y.
The Horticulture Journal 84 (2015) 295-304.
Software development for estimating the concentration of radioactive cesium in the skeletal muscles ofcattle from blood samples
T. Fukuda, M. Hiji, Y. Kino, Y. Abe, H. Amashiro, J. Kabayashi, Y. Shimizu, A. Takahashi, T.
Suzuki, M. Chiba, K. Inoue, Y. Kuwahara, M. Morimoto, M. Katayama, K. Donai, H. Shinoda,
T. Sekine, M. Fukumoto, E. Isogai
Animal Science Journal, published online: 30 SEP 2015 (DOI: 10.1111/asj.12490).
A comprehensive dose evaluation project concerning animals affected by the Fukushima Daiichi Nuclear
Power Plant accident: its set-up and progress
Shintaro Takahashi, Kazuya Inoue, Masatoshi Suzuki, Yusuke Urushihara, Yoshikazu Kuwahara, Gohei Hayashi, Yashushi Kino, Tsutomu Sekine, Yasuyuki Abe, Tomokazu Fukuda,
Emiko Isogai, Hideaki Yamashiro, Manabu Fukumoto
Journal of Radiation Research, 56 (2015) i36-i41.
Electron probe X-ray microanalysis of boar and inobuta testes after the Fukushima accident
H. Yamashiro, Y. Abe, G. Hayashi, Y. Urushihara,Y. Kuwahara,M. Suzuki, J. Kobayashi,Y.
Kino, T. Fukuda, B. Tong, S. Takino, Y. Sugano, R. Iwashima, T. Yamada, E. Isogai, M. Fukumoto
Journal of Radiation Research, 56 (2015) i42-i47.

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Cesium radioactivity in peripheral blood is linearly correlated to that in skeletal muscle: Analyses ofcattle within the evacuation zone of the Fukushima Daiichi Nuclear Power Plant
Tomokazu Fukuda, Yasushi Kino, Yasuyuki Abe, Hideaki Yamashiro, Jin Kobayashi, Yoshinaka Shimizu, Atsushi Takahashi, Toshihiko Suzuki, Mirei Chiba, Shintaro Takahashi, Kazuya
Inoue, Yoshikazu Kuwahara, Motoko Morimoto, Hisashi Shinoda, Masahiro Hiji, Tsutomu
Sekine, Manabu Fukumoto, Emiko Isogai
Animal Science Journal, 86 (2015) 120-124.
Decay dynamics of the unbound 25 O and 26 O nuclei
K. Hagino and H. Sagawa
Phys. Rev. C93 (2016) 034330/1-12.
Are there good probes for the di-neutron correlation in light neutron-rich nuclei?
K. Hagino and H. Sagawa
Few-Body Systems 57 (2016) 185-193.
Generator coordinate method for hypernuclear spectroscopy with a covariant density functional
H. Mei, K. Hagino and J.M. Yao
Phys. Rev. C93 (2016) 011301(R)/1-5.
Enhancement factor for two-neutron transfer reactions with a schematic coupled-channels model
K. Hagino and G. Scamps
Phys. Rev. C92 (2015) 064602/1-4.
Coupled-channels description of multi-nucleon transfer and fusion reactions at energies around and far
below the Coulomb barrier
G. Scamps and K. Hagino
Phys. Rev. C92 (2015) 054614/1-10.
Influence of vibrational excitation on surface diffuseness of the internuclear potential: Study throughheavy-ion quasi-elastic scattering at deep-subbarrier energies
G. Kaur, B.R. Behera, A. Jhingan, P. Sugathan, and K. Hagino
Phys. Rev. C92 (2015) 044609/1-7.
Quasi-elastic barrier distributions for 20 Ne+58,60,61 Ni systems: Influence of weak channels
A. Trzcinska, E. Piasecki, K. Hagino, W. Czarnacki, P. Decowski, N. Keleey, M. Kisielinski, P.
Koczon, A. Kordyasz, E. Koshchiy, M. Kowalczyk, B. Lommel, M. Palacz, A. Stolarz, I. Strojek,
and K. Zerva
Phys. Rev. C92 (2015) 034619/1-6.
Theoretical models for exotic nuclei
H. Sagawa and K. Hagino
Euro. Phys. J. A51 (2015) 102/1-31.
Three-dimensional mesh calculations for covariant density functional theory
Y. Tanimura, K. Hagino, and H.Z. Liang
Prog. Theo. Exp. Phys. 2015 (2015) 073D01/1-29.

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Semi-microscopic modeling of heavy-ion fusion reactions with multi-reference covariant density functional theory
K. Hagino and J.M. Yao
Phys. Rev. C91 (2015) 064606/1-11.
Microscopic study of low-lying spectra of Lambda hypernuclei based on a beyond-mean-field approachwith covariant energy density functional
H. Mei, K. Hagino, J.M. Yao, and T. Motoba
Phys. Rev. C91 (2015) 064305/1-16.
Examination of fusion cross sections and fusion oscillations with a generalized Wong formula
N. Rowley and K. Hagino
Phys. Rev. C91 (2015) 044617/1-13.
Multi-dimensional fission model with a complex absorbing potential
G. Scamps and K. Hagino
Phys. Rev. C91 (2015) 044606/1-6.
High resolution spectroscopic study of 10
Λ Be
T. Gogami, C. Chen, D. Kawama, P. Achenbach, A. Ahmidouch, I. Albayrak, D. Androic, A.
Asaturyan, R. Asaturyan, O. Ates, P. Baturin, R. Badui, W. Boeglin, J. Bono, E. Brash, P.
Carter, A. Chiba, E. Christy, S. Danagoulian, R. De Leo, D. Doi, M. Elaasar, R. Ent, Y. Fujii,
M. Fujita, M. Furic, M. Gabrielyan, L. Gan, F. Garibaldi, D. Gaskell, A. Gasparian, Y. Han, O.
Hashimoto, T. Horn, B. Hu, Ed. V. Hungerford, M. Jones, H. Kanda, M. Kaneta, S. Kato, M.
Kawai, H. Khanal, M. Kohl, A. Liyanage, W. Luo, K. Maeda, A. Margaryan, P. Markowitz, 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, X. Qiu, J. Reinhold, V.M. Rodriguez, C. Samanta, B. Sawatzky, T.
Seva, A. Shichijo, V. Tadevosyan, L. Tang, N. Taniya, K. Tsukada, M. Veilleux, W. Vulcan,
F.R. Wesselmann, S.A. Wood, T. Yamamoto, L. Ya, Z. Ye, K. Yokota, L. Yuan, S. Zhamkochyan,
L. ZhuPhys.Rev. C93 (2016) no.3, 034314.
A fast profile monitor with scintillating fiber hodoscopes for high-intensity photon beams
T. Ishikawa, H. Fujimura, R. Hamano, R. Hashimoto, Y. Honda, T. Ishida, S. Kaida, H. Kanda,
S. Kido, Y. Matsumura, M. Miyabe, K. Mizutani, I. Nagasawa, A. Nakamura, K. Nanbu, K.
Nawa, S. Ogushi, H. Shimizu, H. Sugai, K. Suzuki, K. Takahashi, S. Takahashi, Y. Taniguchi,
A.O. Tokiyasu, Y. Tsuchikawa, H. Yamazaki
Nucl. Instr. Meth. A811 (2016) 124-132.
High-Precision Three-Dimensional Field Mapping of a High Resolution Magnetic Spectrometer for Hypernuclear Spectroscopy at JLabYu Fujii, Osamu Hashimoto, Toshinobu Miyoshi, Satoshi N Nakamura, Atsushi Ohtani,
Yuichi Okayasu, Masamichi Oyamada, Yosuke Yamamoto, Seigo Kato, Jumei Matsui, Kat-

137
suhisa Sako, Brindza Paul
Nuclear Inst. and Methods in Physics Research A 795 (2015) 351-363.
Observation of 4Λ H Hyperhydrogen by Decay-Pion Spectroscopy in Electron Scattering
A. Esser, S. Nagao, F. Schulz, P. Achenbach, C. Ayerbe Gayoso, R. Bhm,O. Borodina D. Bosnar,
V. Bozkurt,L. Debenjak, M. O. Distler, I. Frii, Y. Fujii, T. Gogami, O. Hashimoto, S. Hirose,
H. Kanda, M. Kaneta,E. Kim, Y. Kohl,J. Kusaka, A. Margaryan, H. Merkel, M. Mihovilovi,
U. Mller, S. N. Nakamura, J. Pochodzalla,C. Rappold, J. Reinhold, T. R. Saito, A. Sanchez
Lorente, S. Snchez Majos, B. S. Schlimme, M. Schoth,C. Sfienti, S. irca, L. Tang, M. Thiel, K.
Tsukada, A. Weber, and K. Yoshida
Physical Review Letters 114 (2015) 232501.
Backward-angle photoproduction of ω and η mesons from protons in the photon energy range from 1.5
to 3.0 GeV
Y. Morino, Y. Nakatsugawa, M. Yosoi, M. Niiyama, M. Sumihama, T. Nakano, D. S. Ahn, J.
K. Ahn, S. Ajimura, W. C. Chang, J. Y. Chen, S. Dat, H. Fujimura, S. Fukui, K. Hicks, T.
Hiraiwa, T. Hotta, S. H. Hwang, K. Imai, T. Ishikawa, Y. Kato, H. Kawai, M. J. Kim, H. Kohri,
Y. Kon, P. J. Lin, K. Mase, Y. Maeda, M. Miyabe, N. Muramatsu, H. Noumi, Y. Ohashi, T.
Ohta, M. Oka, J. D. Parker, C. Rangacharyulus, S. Y. Ryu, T. Saito, T. Sawada, H. Shimizu,
E. A. Strokovsky, Y. Sugaya, K. Suzuki, K. Tanida, A. Tokiyasu1, T. Tomioka, T. Tsunemi, M.
Uchida, R. Yamamura, and T. Yorita
PTEP 2015 (2015) 013D01.
Scaling properties of fractional momentum loss of high-pT hadrons in nucleus-nucleus collisions at√

sNNfrom 62.4 GeV to 2.76 TeV
A. Adare et al. (PHENIX Collaboration)
Physical Review C 93, 024911 (2016)
Transverse energy production and charged-particle multiplicity at midrapidity in various systems from√sNN =7.7 to 200 GeV
A. Adare et al. (PHENIX Collaboration)
Physical Review C 93, 024901(2016).
Measurements of Elliptic and Triangular Flow in High-Multiplicity 3 He+Au Collisions at√

sNN =200GeV

A. Adare et al. (PHENIX Collaboration)
Physical Review Letter 115, 142301 (2015)
Systematic study of azimuthal anisotropy in Cu + Cu and Au + Au collisions at√

sNN =62.4 and 200 GeV

A. Adare et al. (PHENIX Collaboration)
Physical Review C 92, 034913 (2015).
Transmutation Reactions Induced by Deuterium Permeation through Nano-structured Pd Multilayer
Thin Film
Y. Iwamura, T. Itoh and S. Tsuruga
Current Science, Vol. 108, NO. 4, (2015) 628-632.

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Dynamical concentration and static retention of deuterium in tungsten foil studied by low energy D(d,p)T
reaction and elastic recoil detection
J.T. Zhao, Q. Wang, D.D. Liu, Z.H. Wang, T.S. Wang and J. Kasagi
Nucl. Instr. Meth. B 360 (2015) 139144.

Papers Published in International Conference Proceedings
Cherenkov Ring Camera for Direct Observation of the Longitudinal Phase Space of the Beam Extracted
from RF Gun
K. Nanbu, A. Lueangaramwong, K. Takahashi, S. Kashiwagi, F. Hinode, T. Muto, H. Saito, I.
Nagasawa, C. Tokoku, E. Kobayashi and H. Hama
Proc. 12th Eco-Energy and Materials Science and Engineering Symposium (EMSES2015),
Krabi, Thailand, June 11-14, 2015, pp370-372.
Proof-of-Principle Experiment of Velocity Bunching for Ultra-short Electron Pulse Production
S. Kashiwagi, F. Hinode, T. Muto, H. Saito, K. Nanbu, I. Nagasawa, K. Takahashi, C. Tokoku,
E. Kobayashi and H. Hama
Proc. 12th Eco-Energy and Materials Science and Engineering Symposium (EMSES2015),
Krabi, Thailand, June 11-14, 2015, pp373-376.
An Optimization of ILC Positron Source for Electron-Driven Scheme
Y. Seimiya, M. Kuriki, M. Urano, S. Kashiwagi, T. Okugi, T. Omori, M. Satoh, J. Urakawa, T.
Takahashi
Proceedings of IPAC2015, Richmond, VA, USA, WEPWA017, pp2529- 2531.
GaAs Photocathode Activation with CsTe Thin Film
M. Kuriki, Y. Seimiya, K. Uchida, S. Kashiwagi
Proceedings of IPAC2015, Richmond, VA, USA, TUPWA062, pp1567-1569.
FEL Enhancement by Microbuch Structure Made with Phase-Space Rotation
M. Kuriki, Y. Seimiya, S. Chen, K. Ohmi, J. Urakawa, S. Kashiwagi, R. Kato
Proceedings of IPAC2015, Richmond, VA, USA, TUPWA063, pp1570-1572.
Extremely Short Electron Bunch Generation for Producing THz Superradiance at T-ACTS, Tohoku University
S. Kashiwagi, F. Hinode, T. Muto, H. Saito, T. Abe, Y. Shibasaki, K. Nanbu, I. Nagasawa, K.
Takahashi, C. Tokoku, E. Kobayashi ,H. Hama
Proceedings of 8th International Workshop on Infrared Microscopy and Spectroscopy using
Accelerator Based Sources (WIRMS 2015), 2015.
Production of Z-polarized Coherent Cherenkov Light in THz Region
H. Hama, K. Nanbu , F. Hinode , S. Kashiwagi , T. Muto , H. Saito , T. Abe , Y. Shibasaki , I.
Nagasawa , K. Takahashi , C. Tokoku , E. Kobayashi
Proceedings of 8th International Workshop on Infrared Microscopy and Spectroscopy using
Accelerator Based Sources (WIRMS 2015), 2015.

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SCRIT Electron Scattering Facility
Toshimi Suda, Akitomo Enozokizono, Masahiro Hara, Yuji Haraguchi, Sin ichi Ichikawa,Kazuyoshi Kurita, Saki Matsuo, Tetsuya Ohnishi, Tadaaki Tamae, Mamoru Togasaki, Kyo
Tsukada,Teruaki Tsuru, Shuo Wang, Shunpei Yoneyama and Masanori Wakasugi
JPS Conf. Proc. Volume 6 (2015) 030100.
Study of ΛN Interaction via the γ-ray Spectroscopy of 4 ΛHe and 19 ΛF (E13-1st)
T.O. Yamamoto et al.
JPS Conf. Proc. 8 (2015) 021017, 1-6.
Measurement of the Λ Spin-flip B(M1) Value in Hypernuclei
Y. Sasaki et al.
JPS Conf. Proc. 8 (2015) 0210173, 1-4.
J-PARC E19 Experiment: Pentaquark Θ+ Search in Hadronic Reaction at J-PARC
Tomonori .N. Takahashi et al.
JPS Conf. Proc. 8 (2015) 022011, 1-6.
J-PARC E27 Experiment to Search for a K− pp Bound State
Yudai Ichikawa et al.
JPS Conf. Proc. 8 (2015) 021020, 1-7.
Three-body calculation of exotic molecules with negatively charged massive particle
Yasushi Kino
Journal of Physics: Conference Series, 635 (2015) 072089.
Ps slowing down process below the Ps break-up energy in Ar gas
Yosuke Sano, Yasushi Kino, Toshitaka Oka, Tsutomu Sekine
Journal of Physics: Conference Series, 635 (2015) 052088.
Relativistic effects in positronic alkali atoms
Takuma Yamashita, Yasushi Kino
Journal of Physics: Conference Series, 635 (2015) 052086.
Kinetic energy of Ps formed by Ore mechanism in Ar gas
Yosuke Sano, Yasushi Kino, Toshitaka Oka, Tsutomu Sekine
Journal of Physics: Conference Series, 618 (2015) 012010.
High-precision calculation of loosely bound states of LiPs+ and NaPs+
Takuma Yamashita, Yasushi Kino
Journal of Physics: Conference Series, 618 (2015) 012009.
Three-dimensional mesh calculations for covariant density functional theory
Y. Tanimura, K. Hagino, and H. Liang
AIP Conf. Proc. 1681 (2015) 03008/1-4.
Pairing interaction and reaction mechanism for one- and two-particle transfer reactions: A simple modelin one dimension
A. Vitturi, L. Moschini, K. Hagino, and A. Moro140
AIP Conf. Proc. 1681 (2015) 060001/1-6.
Neutrinoless double-beta decay in covariant density functional theory
P. Ring, J.M. Yao, L.S. Song, K. Hagino, and J. MengAIP Conf. Proc. 1681 (2015) 050008/1-4.
Nuclear Transmutation of long-lived nucleides with laser comption scattering: quantitative analysis bytheoretical approach
S. Takai and K. Hagino
in ”Nuclear Back-end and Transmutation Technology for Waste Disposal” edited by K. Nakajima (Springer Open, 2014), p. 3-11.
Two-nucleon Correlations in the Decay of Unbound Nuclei beyond the Drip Lines
K. Hagino and H. Sagawa
JPS Conf. Proc. 6 (2015) 020001/1-020001/6.
Subbarrier fusion of carbon isotopes: from resonance structure to fusion oscillations
K. Hagino and N. Rowley
J. of Phys. Conf. Series 590 (2015) 012020/1-6.
Experimental investigations of the hypernucleus 4Λ H
P. Achenbach , F. Schulz, S. Aulenbacher, J. Berii, S. Bleser, R. Bhm, D. Bosnar, L. Correa,
M.O. Distler, A. Esser, H. Fonvieille, I. Frii, Y. Fujii, M. Fujita, T. Gogami, H. Kanda, M.
Kaneta, S. Kegel, Y. Kohl, W. Kusaka, A. Margaryan, H. Merkel, M. Mihovilovi, U. Mller, S.
Nagao, S.N. Nakamura, J. Pochodzalla, A. Sanchez Lorente, B.S. Schlimme, M. Schoth, C.
Sfienti, S. irca, M. Steinen, Y. Takahashi, L. Tang, M. Thiel, K. Tsukada, A. Tyukin, A. Weber
EPJ Web Conf. 113 (2016) 07001
The SCRIT electron scattering facility project at RIKEN RI beam factory
T. Ohnishi, A. Enokizono, M. Hara, T. Hori, S. Ichikawa, K. Kurita, S. Matsuo, T. Suda, T.
Tamae, M. Togasaki, K. Tsukada, T. Tsuru, S. Wang, S. Yoneyama, M. Wakasugi
Phys.Scripta T166 (2015) 014071.
High Resolution Λ Hypernuclear Spectroscopy with Electron Beams
T. Gogami, P. Achenbach, A. Ahmidouch, I. Albayrak, D. Androic, A. Asaturyan, R. Asaturyan,
O. Ates, P. Baturin, R. Badui, W. Boeglin, J. Bono, E. Brash, P. Carter, C. Chen, A. Chiba, E.
Christy, S. Danagoulian, R. De Leo, D. Doi, M. Elaasar, R. Ent, Y. Fujii, M. Fujita, M. Furic,
M. Gabrielyan, L. Gan, F. Garibaldi, D. Gaskell, A. Gasparian, O. Hashimoto, T. Horn, B.
Hu, Ed. V. Hungerford, M. Jones, H. Kanda, M. Kaneta, S. Kato, M. Kawai, D. Kawama, H.
Khanal, M. Kohl, A. Liyanage, W. Luo, K. Maeda, A. Margaryan, P. Markowitz, 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, X. Qiu, J. Reinhold, V. M. Rodriguez, C. Samanta, B. Sawatzky, T.
Seva, A. Shichijo, V. Tadevosyan, L. Tang, N. Taniya, K. Tsukada, M. Veilleux, W. Vulcan, F.
R. Wesselmann, S. A. Wood, T. Yamamoto, L. Ya, Z. Ye, K. Yokota, L. Yuan, S. Zhamkochyan,

141
and L. Zhu
JPS Conf. Proc. 8, 0200 (205).
Photoproduction of K+ Λ and K0 Λ on Deuteron
Takao Fujii, Brian Beckford, Yu Fujii, Osamu Hashimoto, Takatsugu Ishikawa, Hiroki Kanda,*,Masashi Kaneta, Chigusa Kimura, Takeshi Koike, Kazushige Maeda, Koji Miwa, Satoshi N.
Nakamura, Hirokazu Tamura, Fumiya Yamamoto, and Hirohito Yamazaki for the NKS2 collaboration
JPS Conf. Proc. 8, 021003 (2015).
Double neutral pion photoproduction off the proton with FOREST at ELPH
Q. He, H. Fujimura, H. Fukasawa, R. Hashimoto, Y. Honda, T. Ishikawa, T. Iwata, S. Kaida,
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, 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, H.Y. Yoshida
EPJ Web of Conferences 109 (2016) 04004 (Proceedings of OMEG 2015).
High Resolution Λ Hypernuclear Spectroscopy with Electron Beams
T. Gogami, P. Achenbach, A. Ahmidouch, I. Albayrak, D. Androic, A. Asaturyan, R. Asaturyan,
O. Ates, P. Baturin, R. Badui, W. Boeglin, J. Bono, E. Brash, P. Carter, C. Chen, A. Chiba, E.
Christy, S. Danagoulian, R. De Leo, D. Doi, M. Elaasar, R. Ent, Y. Fujii, M. Fujita, M. Furic,
M. Gabrielyan, L. Gan, F. Garibaldi, D. Gaskell, A. Gasparian, O. Hashimoto, T. Horn, B.
Hu, Ed. V. Hungerford, M. Jones, H. Kanda, M. Kaneta, S. Kato, M. Kawai, D. Kawama, H.
Khanal, M. Kohl, A. Liyanage, W. Luo, K. Maeda, A. Margaryan, P. Markowitz, 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, X. Qiu, J. Reinhold, V. M. Rodriguez, C. Samanta, B. Sawatzky, T.
Seva, A. Shichijo, V. Tadevosyan, L. Tang, N. Taniya, K. Tsukada, M. Veilleux, W. Vulcan, F.
R. Wesselmann, S. A. Wood, T. Yamamoto, L. Ya, Z. Ye, K. Yokota, L. Yuan, S. Zhamkochyan,
and L. Zhu
JPS Conference Proceedings 8 (2015) 021010.
Progress of the Hypernuclear Decay Pion Spectroscopy Program at MAMI-C
Sho Nagao, Patrick Achenbach, Naoki Arai, Carlos Ayerbe Gayoso, Ralph Bohm, Olga Borodina, Damir Bosnar, Vakkas Bozsurt, Luka Devenjak, Michael O. Distler, Anselm Esser, Manami Fujita, Ivica Frisic, Yuu Fujii, Toshiyuki Gogami, Mar Gmez Rodrguez, Satoshi Hirose,
Hiroki Kanda, Masashi Kaneta, Eunhee Kim, Junichiro Kusaka, Amur Margaryan, Harald Merkel, Ulrich Mller, Satoshi N. Nakamura, Josef Pochodzalla, Christophe Rappold, Joerg Reinhold, Takehiko R. Saito, Alicia Sanchez Lorente, Salvador Snchez Majos, Bjrn Sren
Schlimme, Matthias Schoth, Florian Schulz, Concettina Sfienti, Simon Sirca, Yuta Takahashi,
Liguang Tang, Michaela Thiel, Kyo Tsukada, Daisuke Uchiyama, and A1 hypernuclear col-

142
laboration
JPS Conference Proceedings 8 (2015) 021012.
Experimental investigations of the hypernucleus 4Λ He
P. Achenbach, F. Shulz, S. Aulenbacher, J. Berii, S. Bleser, R. Bhm, D. Bosnar, L. Correa, M.
O. Distler, A. Esser, H. Fonvieille, I. Frii, Y. Fujii, M. Fujita, T. Gogami, H. Kanda, M. Kaneta,
S. Kegel, Y. Kohl, W. Kusaka, A. Margaryan, H. Merkel, M. Mihovilovi, U. Mller, S. Nagao,
S.N. Nakamura, J. Pochodzalla, A. Sanchez Lorente, B.S. Schlimme, M. Schoth, C. Sfienti, S.
irca, M. Steinen, Y. Takahashi, L. Tang, M. Thiel, K. Tsukada, A. Tyukin, A. Weber
EPJ Web of Conferences 113 (2016) 07001,
The Launch of a New Plan on Condensed Matter Nuclear Science at Tohoku University
Y. Iwamura, J. Kasagi, H. Kikunaga, H. Yoshino, T. Itoh, M. Hattori, T. Mizuno
Proceeding of the 19th International Conference on Condensed Matter Nuclear Science, to be
published.

Invited Talk and Oral Presentations at International Conferences
Conceptual design of variable polarized THz source based on crossed-undulator superradiant (Oral presentation)
H. Hama
The 6th Asian Forum for Accelerators and Detectors, Hsinchu, Taiwan, Jan. 26-27, 2015.
Expected performance of a high brilliant 3 GeV light source project, SLiT-J (Oral presentation)
H. Hama
The German-Japanese University Consortium

HeKKSaGOn

meeting on Mechanobiology,

Tohoku University, Sendai, Apr. 16, 2015.
Cherenkov Ring Camera for Direct Observation of the Longitudinal Phase Space of the Beam Extracted
from RF Gun (Oral presentation)
H. Hama
The 12th Eco-Energy and Materials Science and Engineering Symposium (EMSES2015),
Krabi, Thailand, June 11-14, 2015.
SLiT-J, a high brilliant compact 3GeV light source project in Japan, at a glance (Invited oral)
H. Hama
MAX-IV Laboratory, Lund University, Lund, Sweden, Dec. 14, 2015.
Proof-of-Principle Experiment of Velocity Bunching for Ultra-short Electron Pulse Production (Oral presentation)
S. Kashiwagi, F. Hinode, T. Muto, H. Saito, K. Nanbu, I. Nagasawa, K. Takahashi, C. Tokoku,
E. Kobayashi and H. Hama
The 12th Eco-Energy and Materials Science and Engineering Symposium (EMSES2015),
Krabi, Thailand, June 11-14, 2015.
Extremely Short Electron Bunch Generation for Producing THz Superradiance at T-ACTS, Tohoku Uni-

143
versity (Oral presentation)
S. Kashiwagi, F. Hinode, T. Muto, H. Saito, T. Abe, Y. Shibasaki, K. Nanbu, I. Nagasawa, K.
Takahashi, C. Tokoku, E. Kobayashi and H. Hama
The 8th International Workshop on Infrared Microscopy and Spectroscopy using Accelerator
Based Sources (WIRMS 2015), Riverhead, NY, Oct. 11-15, 2015.
Probing the relative momentum of two-nucleon system in 6 He and 6 Li (Invited oral)
T. Suda, N. Khai, A. Yoshida and I. Tanihata
High-Resolution Spectroscopy and Tensor Interaction 2015, Osaka、2015 年 Nov. 16-19, 2015.
Recent Achievements at J-PARC and Future Prospects of Hypernuclear Study (Invited oral)
H. Tamura
Hypernuclear Workshop 2016 Jefferson Laboratory, Newport News, VA, USA, March 14-15,
2016.
Present Status and Future Prospects of Hypernuclear Physics at J-PARC (Invited oral)
H. TamuraWorkshop on Hypernuclei studies and Strangeness production, CEA Saclay , France, January
19-21, 2016.
Hypernuclear physics at J-PARC (Invited oral)
H. Tamura
Frontiers in hadron and nuclear physics with strangeness and charm. ECT* Trento, Italy,
October 19-23, 2015.
Gamma-ray spectroscopy of hypernuclei - recent results and prospect at J-PARC (Invited oral)
H. Tamura
12th International Conference on Hypernuclear and Strange Particle Physics (HYP2015),
Tohoku University, Sendai, September 7-12, 2015.
Overview on hypernuclei –What are exciting now? (Invited oral)
H. Tamura
EMMI Workshop on anti-matter, hyper-matter and exotica production at the LHC, CERN,
Geneva, Switzerland, July 20-22, 2015.
Energy levels and structures of exotic molecules with negatively charged particles (Oral presentation)
Y. Kino12th International conference on low energy antiproton physics, Kanazawa, Japan, March
6-11, 2016.
Di-neutron correlations in the two-particle decay of unbound nuclei (Invited oral)
K. Hagino
Weakly Bound Exotic Nuclei, Natal, Brazil, May 24 May 30, 2015.
Present status of coupled-channels calculations for heavy-ion fusion reactions (Invited oral)
K. Hagino
Nucleus-nucleus 2015, Catania, Italy, June 21-June 26, 2015.

144
Beyond-mean-field approach to low-lying spectra of Λ hypernuclei (Oral presentation)
K. Hagino
The 12th International Conference on Hypernuclear and Strange Particle Physics, Sendai,
Japan, September 7-12, 2015.
Two-neutron decay of the 26 O nucleus (Invited oral)
K. HaginoLong-term workshop on Computational Advances in Nuclear and Hadron Physics, Kyoto,
Japan, Sep. 21-Oct. 30, 2015.
Recent developments in heavy-ion fusion reactions around the Coulomb barrier (Oral presentation)
K. Hagino
The 5th international workshop on compound-nuclear reactions and related topics (CNR*15),
Tokyo, Japan, Oct. 19-23, 2015.
Reactions with heavy nuclei (Invited oral)
K. Hagino
FRIB-theory alliance inaugural meeting, East Lansing, USA, March 31-April 1, 2016.
Study of Lambda hypernuclei with electron beams (Invited oral)
S. N. Nakamura
Nuclear Structure and Reactions: Weak, Strange and Exotic (Hirschegg2015) Kleinwalsertal,
Austria, Jan. 11-17, 2015.
Hypernuclear spectroscopy via (e,e K+ ) reaction (Invited oral)
S. N. Nakamura
12th International Conference on Hypernuclear and Strange Particle Physics (HYP2015) ,Sendai, Japan, Sep. 7-12, 2015.
Spectroscopy of Lambda hypernuclei with electron beams (Invited oral)
S. N. Nakamura
Fifth International Conference on Nuclear Fragmentation (NUFRA2015) , Kemer, Turkey,
Oct. 4-12, 2015.
High-Resolution Reaction Spectroscopy of Lambda-Hypernuclei (Invited oral)
S. N. Nakamura
International workshop on physics at the extended hadron experimental facility of J-PARC
Tokai, Japan, March 5-6, 2016.
Opening and Highlights of Hypernuclear Study at JLab (Oral presentation)
S. N. Nakamura
The 2nd JLab Hypernuclear Workshop, Newport News, USA, 14-15 March 2016.
Spectroscopic Study of Medium Heavy Hypernuclei (Invited oral)
S. N. Nakamura
The 2nd JLab Hypernuclear Workshop, Newport News, USA, 14-15 March 2016.
Meson photoproduction experiments at ELPH, Tohoku University (Invited oral)

145
T. Ishikawa
The 10th International Workshop on the Physics of Excited Nucleons (NSTAR2015), Suita,
Japan, May 25-28, 2015.
Recent results and future prospects of LEPS and LEPS2 (Oral presentation)
M. Miyabe
ELPH Workshop C013, Sendai Japan, Jul. 13, 2015.
Study of Σπ invariant mass spectrum in the d (γ, K+ ) X reaction (Oral presentation)
A. O. Tokiyasu
HYP2015, Sendai in Japan, September 7-15, 2015.
The recent results of strangeness photoproduction in the threshold region at

ELPH-Tohoku (Oralpresentation)
H. Kanda
HYP2015: International Conference on Hypernuclear and Strange Particle Physics, Sendai,
Japan, Sep. 7-12, 2015.
Double pion photoproduction on a deuteron for the search of two-baryonic resonances at ELPH (Invitedoral)
H. Kanda
ELPH Workshop C013: Meson Production and Meson Baryon Interaction (MPMBI2015),
Sendai, Japan, Sep. 13―15, 2015.
Study of Λ-n interaction via FSI in γ+d reaction (Oral presentation)
M. Kaneta
HYP2015: 12th International Conference on Hypernuclear and Strange Particle Physics,
Sendai, Japan, Sep 7-11, 2015.
The Launch of a New Plan on Condensed Matter Nuclear Science at Tohoku University (Oral presentation)
Y. Iwamura
19th International Conference on Condensed Matter Nuclear Science, Padua, Italy, April 1317, 2015.
Screening energy of the D+D reaction in an electron plasma deduced from cooperating colliding reaction(Oral presentation)
J. Kasagi
The 19th International Conference on Condensed Matter Nuclear Science ICCF19, Padua,
Italy, April 13-17, 2015.
Near threshold K0 Λ photoproduction on the neutron studied with an electromagnetic calorimeter, FOREST (Oral presentation)
Y. Tsuchikawa
The 10th International Workshop on the Physics of Excited Nucleons (NSTAR2015), Osaka,
May 25-28, 2015.

146
The performance study of an electro-magnetic calorimeter for the LEPS2/BGOegg experiment (Oralpresentation)
Y. Matsumura
The 10th International Workshop on the Physics of Excited Nucleons (NSTAR2015), Osaka,
May 25-28, 2015.
0

K Λ photoproduction studied with an electromagnetic calorimeter, FOREST (Oral presentation)
Y. Tsuchikawa
The 12th International Conference on Hypernuclear and Strange Particle Physics (HYP2015)
Sendai, Sep.7-12, 2015.

学位論文 (電子光理学研究センター所属)
博士論文「Near-threshold K0 Λ photoproduction on the neutron」
土川 雄介，平成 27 年，東北大学
修士論文 「メソン光生成反応実験のための GeV 光子ビームプロファイルモニターの開発」
木戸 聡, 平成 27 年, 東北大学
修士論文 「速度集群法を用いた極短パルス電子ビームの生成」
齊藤寛峻, 平成 27 年, 東北大学

学位論文 (他機関所属)
修士論文「ミューオン-電子転換過程探索実験に用いるストローチューブ飛跡検出器の開発」
田中 聡一,

平成 27 年度，九州大学

学士論文「シングルコンパレータ法による光量子放射化分析 岩石試料への応用」
寺岬 均,

平成 27 年度，首都大学東京

IV. Members of Committees

147

Steering Committee
2015

Hiroyuki HAMA*

ELPH

Hajime SHIMIZU

ELPHToshimi SUDA

ELPH

Fujio HINODE

ELPH

Shigeru KASHIWAGI

ELPHNorihito MURAMATSU

ELPH

Hidetoshi KIKUNAGA

ELPH

Hirokazu TAMURA

Graduate School of Science

Satoshi NAKAMURA

Graduate School of Science

Kazushige MAEDA

Graduate School of Science

Kouichi HAGINO

Graduate School of Science

Fuminori MISAIZU

Graduate School of Science

Yasushi KINO

Graduate School of Science

Nobuyuki Uozumi

Graduate School of Engineering

Atsuki TERAKAWA

Graduate School of 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

Yasuhiro SAKEMI

Cyclotron and Radioisotope Center

Tetsuo TANIUCHI

Center for Interdisciplinary Research* Chairperson

148

General Advisory Committee
2015

Hiroyuki HAMA*

ELPH

Hajime SHIMIZU

ELPHToshimi SUDA

ELPH

Hidetoshi KIKUNAGA

ELPH

Hirokazu TAMURA

Graduate School of Science

Yasushi KINO

Graduate School of Science

Yasuhiro SAKEMICYRIC

Tetsuo TANIUCHI

CIR

Takahiro IWATA

Yamagata University

Daisuke JIDOTokyo Metropolitan University

Takashi NAKANORCNP, Osaka University

Tomohumi NAGAE

Kyoto University

Hideaki OHGAKI

IAE, Kyoto University

Shigemi SASAKIHSRC, Hiroshima University

Akihiko YOKOYAMA

Kanazawa University

Yasuji OURATokyo Metropolitan University* Chairperson

149

Program Advisory Committee
2015

Hajime SHIMIZU

ELPHToshimi SUDA

ELPH

Satoshi N. Nakamura

Graduate School of Science

Shigeru KASHIWAGI

ELPH

Hidetoshi KIKUNAGA

ELPHAsao YAMAMURA

Institute for Materials Research

Yasuhisa TAJIMA

Yamagata University

Hiroaki OHNISHI

RIKEN

Toshiyuki TAKAHASHI *IPNS, KEK

Yoshihiko SHOJILASTI, University of Hyogo

Yasuji OURATokyo Metropolitan University

Koichi TAKAMIYA

Research Reactor Institute, Kyoto University* Chairperson

V. Approved Experiments

151

平成 27 年度前期採択課題一覧
課題番号

2805

課

題

名

光量子放射化法によるプロメチウム（Pm）内包金属フラーレンの合成を目的と

申込責任者
秋山 和彦

した RI 製造2807

ガスジェット搬送物としての Be-7 の半減期測定

笠松 良崇

2808

高分解能飛行時間測定と光子標識化装置の時間分解能の向上

石川 貴嗣

2809

コンパクト BPM の開発

石川 貴嗣

2810

位置測定可能な電磁カロリメータモジュールの開発

石川 貴嗣

2811

E16 実験 GEM 飛跡検出器の磁場内での性能評価

小沢 恭一郎2812

BM4 用 光子標識化装置の性能評価

神田 浩樹

2813

FOREST 実験の為の光子標識化装置 Tagger2s ワイヤーチェンバーの性能評価

田島 靖久

152

平成 27 年度後期採択課題一覧
課題番号

課

名

申込責任者

2814
2815

BST リングの電子ビームサイズの測定

秋山 和彦

2816

検出器テスト用電子ビームラインの再整備 II

石川 貴嗣

2817

電子の速度と運動量 [学生実験]

石川 貴嗣

2818

STB-Tagger II の高時間分解能化

石川 貴嗣

2819

放射性バナジウム V-48 を用いたバナジウム・レドックスフロー電池の隔膜の研白崎 謙次

Mo (γ,n)

99

題

100

Mo 反応における W コンバーターの厚さ依存性

岡 壽崇

究

2820

HFC を希釈剤として用いた溶媒抽出法による Sr の分離の検討

山村 朝雄

2821

LEPS2 ソレノイド実験用トリガー検出器の性能評価

時安 敦史

2822

J-PARC E14 実験 CsI 検出器両読み時の性能評価

外川

2823

J-PARC E42 実験用タイムプロジェクションチェンバー (HypTPC) の性能評価

杉村 仁志

2824

新素材のシンチレータを用いたサンドイッチカロリメータの開発

田島 靖久

2825

ビームを用いた検出器テスト （4 年生学生実験）

須田 利美

2826

シンチレータの電子線ないしはガンマ線に対する放射線耐性実験

黒澤 俊介

2827

シロイヌナズナのカリウム輸送挙動解明のためのトレーサー製造（II）

魚住 信之

2828

FOREST 実験の為の光子標識化装置 Taggers ワイヤーチェンバーの性能評価

田島 靖久

2829

J-PARC・E21 実験 (COMET 実験) のためのストローチューブトラッカーの開

西口 創

学

発

2830

次世代長期線ニュートリノ振動実験に向けた検出器のテスト実験

南野 彰宏

2831

NKS2 用 標識化光子ビームのコミッショニング

神田 浩樹

2832

線フラットパネルセンサーの陽電子に対する応答の測定

神田 浩樹

2833

COMET 実験用電磁カロリメータの開発

東城 順治

2834

NKS2 用 標識化装置のコミッショニング

神田 浩樹

2835

BST リングの電子ビームサイズの測定

時安 敦史

随時申込

EditorHINODE, Fujio
MURAMATSU, Norihito
MUTO, Toshiya
TSUKADA, Kyo

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/

ELPH ANNUAL REPORT 2015
December 2016

982-0826

仙台市太白区三神峯1-2-1

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

東北大学電子光理学研究センター
電話022-743-3400

Fax

022-743-3402

印刷所 株式会社 東北プリント
仙台市青葉区立町24番24号
TEL 022（263）1166㈹ISSN 2186-7968

ELPH ANNUAL REPORT 2015

ELPH

ANNUAL REPORTTOHOKU UNIVERSITYTOHOKU UNIVERSITY

2015