JAEA-Conf 2023-001
INDC(JPN)-0209
DOI:10.11484/jaea-conf-2023-001

Proceedings of the 2022 Symposium on Nuclear Data
November 17-18, 2022,
BLOSSOM CAFÉ, Main Campus, Kindai University,
Higashiosaka City, Osaka, Japan(Eds.) Nobuhiro SHIGYO, Atsushi KIMURA and Tadafumi SANO

Nuclear Science and Engineering Center
Sector of Nuclear Science Research

February 2024
Japan Atomic Energy Agency

日本原子力研究開発機構

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JAEA-Conf 2023-001
INDC(JPN)-0209
Proceedings of the 2022 Symposium on Nuclear Data
November 17-18, 2022,
BLOSSOM CAFÉ, Main Campus, Kindai University,
Higashiosaka City, Osaka, Japan(Eds.) Nobuhiro SHIGYO*1, Atsushi KIMURA and Tadafumi SANO*2
Nuclear Science and Engineering Center, Sector of Nuclear Science Research,
Japan Atomic Energy Agency,
Tokai-mura, Naka-gun, Ibaraki-ken(Received November 6, 2023)
The 2022 Symposium on Nuclear Data was held at BLOSSOM CAFÉ in Main Campus of Kindai
University on November 17-18, 2022. The symposium was organized by the Nuclear Data Division of theAtomic Energy Society of Japan (AESJ) in cooperation with Investigation Committee on Nuclear Data in
AESJ, Nuclear Science and Engineering Center of Japan Atomic Energy Agency, and High Energy
Accelerator Research Organization.
In the symposium, tutorials " The Future of Nuclear Reactor Physics Experimental Research in Japan"
was proposed and held. two sessions of lectures and discussions were held: "Recent Topics on Nuclear Data".
In addition, recent research progress on experiments, nuclear theory, evaluation, benchmark, and applications
were presented in the poster session. The total number of participants was 76 participants. Each oral andposter presentation was followed by an active question and answer session. This report consists of a total of
22 papers including 4 oral and 18 poster presentations.
Keywords: Nuclear Data Symposium 2022, Experiments, Nuclear Theory, Nuclear Data Evaluation,
Benchmark Test, Nuclear Data Applications*1 Kyushu University*2 Kindai University
Organizers: Tadafumi SANO (Chair, Kindai Univ.), Yosuke IWAMOTO (Vice-chair, JAEA), Tatsuya
KATABUCHI (Tokyo Tech.), Toshiya SANAMI (KEK), Atsushi KIMURA (JAEA), Katsuhisa NISHIO(JAEA), Nobuhiro SHIGYO (Kyushu Univ.), Jun-ichi HORI (Kyoto Univ.), Osamu IWAMOTO (JAEA),
Yuji YAMAGUCHI (JAEA), Kazushi TERADA (Kyoto Univ.)ii

JAEA-Conf 2023-001
INDC(JPN)-0209
2022 年度核データ研究会報告集
2022 年 11 月 17 日～18 日
近畿大学 東大阪キャンパス ブロッサムカフェ
大阪府東大阪市
日本原子力研究開発機構 原子力科学研究部門 原子力基礎工学研究センター（編）執行 信寛*1、木村

敦、佐野 忠史*2(2023 年 11 月 6 日受理)
2022 年度核データ研究会は、2022 年 11 月 17 日〜18 日に、大阪府東大阪市にある近畿大学東大阪キャンパスの BLOSSOM CAFÉ 多目的ホールにて開催された。本研究会は、日本原子力学会
核データ部会が主催、日本原子力学会「シグマ」調査専門委員会、日本原子力研究開発機構原子力基礎工学研究センター、高エネルギー加速器研究機構が共催した。
チュートリアルとして、「我が国の原子炉物理学実験的研究の歴史」を、講演・議論のセッションとして、「核データに関する最近の話題」2 セッションを実施した。さらにポスターセッション
では実験、理論、評価、ベンチマーク、応用など幅広い内容について発表が行われた。参加者数
は 76 名で、それぞれの口頭発表およびポスター発表では活発な質疑応答が行われた。本報告書は、本研究会における口頭発表 4 件、ポスター発表 18 件の合計 22 の論文を掲載している。
キーワード: 2022 年度核データ研究会、実験、原子核理論、核データ評価、ベンチマークテスト、
核データ応用原子力科学研究所：〒319-1195 茨城県那珂郡東海村大字白方 2-4*1 九州大学*2 近畿大学
2022 年度核データ研究会実行委員会：
佐野忠史 (委員長、近畿大学)、岩元洋介 (副委員長、原子力機構)、片渕竜也 (東京工業大学)、
佐波俊哉 (高エネルギー加速器研究機構)、木村敦 (原子力機構)、西尾勝久 (原子力機構)、
執行信寛 (九州大学)、堀順一 (京都大学)、岩本修 (原子力機構)、山口雄司 (原子力機構)、
寺田和司 (京都大学)

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JAEA-Conf 2023-001

Contents
1.

2022 Symposium on Nuclear Data-Programme ······································································ 1Papers presented at Oral sessions

2.

Some memories of relationship with Nuclear Data ·································································· 5
Ken NAKAJIMA (Kyoto Univ.)

3.

40-year experience in nuclear data ····················································································· 11
Satoshi CHIBA (Tokyo Tech.)4.

Conceptual Design Study of New Research Reactor at the Monju Site··········································· 34
Kazufumi TSUJIMOTO (JAEA)

5.

Measurement of 100 MeV-range nuclear reaction data using the fixed field alternating gradient accelerator
at Kyoto University······································································································· 40
Hiroki IWAMOTO (JAEA)

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JAEA-Conf 2023-001

Papers presented at Poster Session
6.

Measurement and evaluation of DD neutron field Characteristics for OKTAVIAN ···························· 46
Hikaru MATSUNAGA (Osaka Univ.) et al.

7.

Production cross sections of 198gAu in proton-induced reactions on natural platinum ·························· 52
Gantumur DAMDINSUREN (Hokkaido Univ.) et al.

8.

Preliminary experiment for measurement of radionuclide yield from nuclear capture reaction of negative
muon························································································································ 56
Yuji YAMAGUCHI (JAEA) et al.

9.

Cross comparison on neutron spectra with Liquid Scintillator and Bonner Sphere Spectrometer ············ 62
Eunji LEE (KEK) et al.

10. New analytical model for momentum distribution on the spallation reaction in inverse kinematics ········· 68
Riku MATSUMURA (RIKEN / Saitama Univ.) et al.
11. Neutron Capture Cross Section Measurement of 129I and 127I using ANNRI at MLF/J-PARC ················ 74
Gerard ROVIRA (JAEA) et al.
12. Measurement of heavy nuclide production cross-section for natPb irradiated with several GeV protons······························································································································· 80
Kenta SUGIHARA (KEK) et al.
13. Improvement of Benchmark Experiment with Gold foil for Large Angle Scattering Reaction Cross Section
at 14MeV Using Two Shadow Bars ···················································································· 86
Rio MIYAZAWA (Osaka Univ.) et al.
14. The comparison of nuclear data and experimental results for photoneutron spectra on Ta, W, and Bi targets
for 17 MeV photons ······································································································ 92
T. NGUYEN (SOKENDAI) et al.
15. Study of GAGG scintillator as a neutron detector ··································································· 97
Ren SAKAI (Kyushu Univ.) et al.
16. Characterization of various types of n-γ mixed fields by using a D-D neutron source ························· 103
Zixu XU (Osaka Univ.) et al.
17. Design investigation of pencil-beam epi-thermal neutron source for validation of low-energy neutron
spectrometer ··············································································································· 109
Yu FUJIWARA (Osaka Univ.) et al.
18. Estimation of the Total Angular Momentum of Resonances using Low-energy Gamma-rays in
Ta(n, γ)182Ta Reaction ································································································· 115

181

Shiori KAWAMURA (Nagoya Univ.) et al.
19. Theoretical study of low-excitation fission phenomena in unstable thorium isotopes ·························· 121
Wataru MIYASAKAI (Kindai Univ.) et al.
20. Theoretical estimation of synthesizing neutron rich nuclei in superheavy mass region ························ 126
S. Nishikawa (Kindai Univ.) et al.

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21. Fission fragment yields of neutron-rich nuclei evaluated by the Langevin model calculation ················ 132
Shoya TANAKA (RIKEN) et al.
22. Extension of R-matrix code AMUR toward analysis on actinide nuclei -A feasibility study on 233U- ······· 138
Satoshi KUNIEDA (JAEA)
23. Processing of JENDL-5 Photonuclear Sublibrary ···································································· 143
Chikara KONNO (JAEA)

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JAEA-Conf 2023-001

目次
1.

2022 年度核データ研究会プログラム·············································································· 1
口頭発表論文2.

核データとのかかわり －いくつかの思い出－································································· 5
中島健 (京都大学)

3.

核データ研究の 40 年 ·································································································· 11
千葉敏 (東京工業大学)

4.

もんじゅサイトに設置する新たな試験研究炉の概念検討 ··················································· 34
辻本和文 (原子力機構)

5.

京都大学 FFAG 加速器を用いた 100 MeV 領域核反応データの測定 ··································· 40
岩元大樹 (原子力機構)

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ポスター発表論文
6.

OKTAVIAN における DD 中性子場特性の測定と評価 ························································ 46
松永大輝 (大阪大学) 他

7.

Production cross sections of 198gAu in proton-induced reactions on natural platinum ·························· 52
Gantumur DAMDINSUREN (北海道大学) 他

8.

負ミュオンの原子核捕獲反応における放射性核種収量の測定のための予備実験 ····················· 56
山口雄司 (原子力機構) 他

9.

Cross comparison on neutron spectra with Liquid scintillator and Bonner Sphere Spectrometry ············ 62
李恩智 (高エネ研) 他

10. 逆運動学法を用いた核破砕反応の運動量分布形成に対する解析モデル ································· 68
松村理久 (理研 / 埼玉大学) 他
11. Neutron Capture Cross Section Measurement of 129I and 127I using ANNRI at MLF/J-PARC ················ 74
Gerard ROVIRA（原子力機構） 他
12.

natPb と数 GeV 陽子の反応による重核の生成断面積測定····················································· 80

杉原健太 (高エネ研) 他
13. 金箔を用いた 14 MeV 中性子による大角度散乱断面積ベンチマーク実験手法の実現可能性検討······························································································································· 86
Rio MIYAZAWA （大阪大学） 他
14. The comparison of nuclear data and experimental results for photoneutron spectra on Ta, W, and Bi targets
for 17 MeV photons ······································································································ 92
T. NGUYEN (高エネ研) 他
15. 中性子検出器としての GAGG シンチレータの研究 ··························································· 97
坂井蓮 (九州大学) 他
16. D-D 中性子源を用いた様々な特性を有する中性子・ガンマ線混在場の設計 ··························· 103
Zixu XU （大阪大学） 他
17. Design investigation of pencil-beam epi-thermal neutron source for validation of low-energy neutron
spectrometer ··············································································································· 109
藤原悠 (大阪大学) 他
18.

181Ta(n,γ)182Ta 反応における低エネルギーガンマ線を用いた共鳴の全角運動量の推定··············· 115

河村しほり (名古屋大学) 他
19. 不安定なトリウム同位体の低励起核分裂現象の理論研究 ··················································· 121
宮堺渉 (近畿大学) 他
20. Theoretical estimation of synthesizing neutron rich nuclei in superheavy mass region ························ 126
西川勝麻 (近畿大学) 他
21. ランジュバン計算による中性子過剰核における核分裂収率の評価 ······································· 132
田中翔也 (理研) 他
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22. アクチノド核データ評価への適用に向けた R 行列理論解析コード AMUR の拡張、および 233U に対する中性子断面積の解析 ·························································································· 138
国枝賢 (原子力機構)
23. JENDL-5 光核サブライブラリの処理 ·············································································· 143
今野力 (原子力機構)

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1.

2022 Symposium on Nuclear Data - Programme
November 17 - 18, 2022

Thursday, November 17
Opening Address (13:30 - 13:40)
Convener: Tadafumi SANO (Kindai Univ.)
Retirement Memorial Lecture (13:40 - 15:00)
Convener: Osamu IWAMOTO (JAEA)
13:40 Some memories of relationship with Nuclear Data
Ken NAKAJIMA (Kyoto Univ.)
14:20 40-year experience in nuclear data
Satoshi CHIBA (Tokyo Tech.)
Break (15:00 - 15:30)
Poster Session (15:30 - 17:00)
Measurement and evaluation of DD neutron field characteristics for OKTAVIAN
Hikaru MATSUNAGA (Osaka Univ.)
Production cross sections of 198gAu in proton-induced reactions on natural platinum
Gantumur DAMDINSUREN (Hokkaido Univ.)
Preliminary experiment for measurement of radionuclide yield from nuclear capture reaction ofnegative muon
Yuji YAMAGUCHI (JAEA)
Measurement of sample reactivity worth of calcium hydride in UTR-KINKI
Takashi KANDA (Kindai Univ.)
Cross comparison on neutron spectra with Liquid scintillator and Bonner Sphere Spectrometry
Eunji LEE (KEK)
New analytical model for momentum distribution on the spallation reaction in inverse kinematics
Riku MATSUMURA (Saitama Univ.)
Neutron Capture Cross Section Measurement of 129I and 127I using ANNRI at MLF/J-PARC
Gerard ROVIRA (JAEA)
Measurement of heavy nuclide production cross section via the reaction between GeV proton and
natPb

Kenta SUGIHARA (KEK)
Experimental examination of activation detector for long-term DT neutron irradiation
Ryota EGUCHI (Osaka Univ.)-1-

JAEA-Conf 2023-001

Improvement of Benchmark Experiment with Gold foil for Large Angle Scattering Reaction Cross
Section at 14MeV Using Two Shadow Bars
Rio MIYAZAWA (Osaka Univ.)
The comparison of nuclear data and experimental results for photoneutron spectra on Ta, W, and Bi
targets for 17 MeV photons
Thuong NGUYEN (SOKENDAI)
Development of sample-added scintillation detector
Takaaki OGISO (Tokyo Tech.)Study of GAGG scintillator as a neutron detector
Ren SAKAI (Kyushu Univ.)
Simulation of Developing Neutron and Gamma-ray Mixed Field based on D-D Neutron Source
Zixu XU (Osaka Univ.)
Design investigation of pencil-beam epi-thermal neutron source for validation of low-energy neutron
spectrometer
Yu FUJIWARA (Osaka Univ.)
Estimation of the total angular momentum of resonances using low- energy gamma-rays in
181Ta(n, γ )182Ta

Shiori KAWAMURA (Nagoya Univ.)
Theoretical study of low-excitation fission phenomena in unstable thorium isotopes
Wataru MIYASAKAI (Kindai Univ.)
Mean-field model dependence in heavy-ion nuclear reaction cross section calculation byantisymmetric molecular dynamics
Yuta MUKOBARA (Tokyo Tech.)
Theoretical estimation of synthesizing neutron rich nuclei in superheavy mass region
Shoma NISHIKAWA (Kindai Univ.)
Study of fission with five-dimensional Cassini shape parameterization
Kazuki OKADA (Kansai Univ.)
Fission fragment yields of neutron-rich nuclei evaluated by the Langevin model calculation
Shoya TANAKA (RIKEN)
Extension of R-matrix code AMUR toward analysis on actinide nuclei– A feasibility study on 233U –Satoshi KUNIEDA (JAEA)
Processing of JENDL-5 photonuclear sublibrary
Chikara KONNO (JAEA)-22

JAEA-Conf 2023-001

Friday, November 18, 2022
Tutorial (09:00 - 10:00)
Convener: Tadafumi SANO (Kindai Univ.)
09:00 The Future of Nuclear Reactor Physics Experimental Research in Japan
Kengo HASHIMOTO (Kindai Univ.)
Recent Topic (1) (10:00 - 11:30)
Convener: Jun-ichi HORI (Kyoto Univ.)
10:00 Conceptual Design Study of New Research Reactor at the Monju Site
Kazufumi TSUJIMOTO (JAEA)
10:30 Measurement of 100 MeV-range nuclear reaction data using the fixed field alternating gradientaccelerator at Kyoto University
Hiroki IWAMOTO (JAEA)
11:00 About Kindai Research Reactor
Tadafumi SANO (Kindai Univ.)
Lunch (11:30 - 13:00)
Recent Topic (2) (13:00 - 14:30)
Convener: Atsushi KIMURA (JAEA)
13:00 Research and development of alpha radiation nuclear medicine treatment using 211At
Takashi NAKANO (RCNP)
13:30 Production of medical radionuclides using electron linear accelerators
Takahiro TADOKORO (Hitachi)
14:00 Half-life change of orbital electron capture modified nuclide 7Be
Tsutomu OHTSUKI (Kyoto Univ.)
Break (14:30 - 15:00)
Nuclear Data Section Award in 2022 (15:00 - 16:30)
Convener: Katsuhisa NISHIO (JAEA)
15:00 Measurement of neutron energy spectrum by 345 MeV/u 238U incident on a copper target
Kenta SUGIHARA (KEK)
15:20 Excitation energy dependence of total kinetic energy of fission fragments
Kazuya SHIMADA (Tokyo Tech.)
15:40 Measurement of fast neutron capture reaction of 243Am
Yu KODAMA (Tokyo Tech.)-33

JAEA-Conf 2023-001

16:00 Incident neutron energy dependent calculation of fission yield and prompt/delayed neutron yield ofU, 238U and 239Pu

235

Shin OKUMURA (IAEA)
Closing Address (16:30 - 17:00)
Tadafumi SANO (Kindai Univ.), Yosuke IWAMOTO (JAEA)-44

JAEA-Conf 2023-001

2.

Some memories of relationship with Nuclear Data

Ken NAKAJIMA
Institute for Integrated Radiation and Nuclear Science, Kyoto University
Asashiro-Nishi 2-1010, Kumatori-cho, Sennan-gun, Osaka 590-0494, Japan
Email: nakajima.ken.5m@kyoto-u.ac.jp

I have had some involvement with nuclear data for 45 years, ever since I heard the term "Nuclear
Data" in the lecture of Nuclear Reactor Physics in my junior year of university. This paper describes
some of my memories of relationship with nuclear data.

1. First contact with Nuclear Data (1978-)I think the first time I became aware of “Nuclear Data” was in the lecture of Nuclear Reactor Physics
in university. There, nuclear data was used mainly as the neutron induced nuclear reaction cross sections.
I didn't understand much about it at the time, but anyway, the nuclear reaction rate could be calculated
by multiplying the neutron flux by the nuclear data (the cross section). The nuclear data were evaluatedby experts, which meant that users of the nuclear data could obtain the reaction rate without knowing thedetails of the nuclear reaction. Although it may be difficult for those who evaluate nuclear data, I had theimpression that it is very convenient for the users because they do not have to perform difficult
calculations.
Later, when I started to use nuclear data in my work, I found that I needed to put in a lot of effort intheir use, but my initial impression has not changed much. As one of the users, I cannot help but admire
the experts who measure and evaluate nuclear data and maintain nuclear data libraries.

2. Use of Nuclear Data at JAERI (1982-)
2.1. NUCEF Design WorkIn 1982, I joined the Japan Atomic Energy Research Institute (JAERI) and was assigned to the
Criticality Safety Laboratory. At that time, the laboratory was designing a new experimental facility forcriticality safety (now called NUCEF [1]), which was to have two critical experimental facilities: thesteady-state critical experimental facility (STACY) to measure the nuclear characteristics such as criticalmass using solution fuel, and the transient critical experimental facility (TRACY) to conduct dynamic
experiments simulating a criticality accident. I was mainly in charge of the TRACY design (Fig. 1).
In the design of those facilities, the critical mass, reactivity coefficient, and kinetic parameters (theeffective delayed neutron fraction and prompt neutron lifetime) were calculated for various fuelconditions, and the core shapes and dimensions and the operation control system were investigated. For
this purpose, it was necessary to perform nuclear calculations, and the SRAC code system, which wasunder development at the time and was also used in the design of the modified JRR-3 reactor, was used

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JAEA-Conf 2023-001

as the nuclear calculation tool. In addition, the KENO-IV code, which was widely used as a Monte Carlocode, was used for criticality calculations for complex geometries. For these nuclear calculations, theJENDL-2 nuclear data library, which was the latest version at that time, was used. The nuclear
calculations require the atomic number density of the target material. Since there was no accurate atomic
number density evaluation formula for uranyl nitrate and/or plutonium solution, the fuel used in thecalculations, the Chemical Process Research Group of the Criticality Safety Laboratory conducted
experimental research and developed a new evaluation formula. In parallel with the nuclear calculations,a new kinetic code for solution fuel systems, AGNES [2] was developed to evaluate the kinetic
experiments to be conducted using TRACY. The reactivity coefficients and kinetic parameters used in
the code were calculated by SRAC.
In the process of these design works, the NUCEF Construction Office was separated from theCriticality Safety Laboratory, and the facility licensing and construction works were carried out mainlyby the NUCEF Construction Office. As a result, STACY and TRACY went critical for the first time in
February and December 1995, respectively. I have heard that the conceptual design work of NUCEF
started in 1981, so it took almost 15 years from the conception to the start of operation. During this period,in addition to the update of the SRAC code, nuclear data were updated from JENDL-2 (1982: 82 nuclides➝ revised in 1985: 181 nuclides) to JENDL-3 (1989: 171 nuclides), JENDL-3.1 (1990: 324 nuclides)
and JENDL-3.2 (1994: 340 nuclides). In principle, it is better to use the new data which reflects the latest
findings, but if the calculation results change during the licensing process, it is necessary to recheck thevalidity of the safety review. Then the calculation environment should be maintained so that the results
obtained in the past can be reproduced. At the same time, it is also necessary to check the impact of
employing the latest findings in the safety review. Even if there is no significant impact, it is required tokeep quality control of past calculations.
2.2. TCA critical experiments
In parallel with the design and construction of NUCEF, various experiments on criticality safety andnuclear characteristics of light water reactors were conducted in the Criticality Safety Laboratory using
the Tank-type Critical Assembly TCA [3] (Fig. 2), which simulates light water reactor cores. Theseexperimental data are used as benchmark data for nuclear data and contribute to improving the accuracyof nuclear data.
In the late 1980s, a new reactor concept, the high-conversion light water reactor (HCLWR), attracted
worldwide attention. To improve the efficiency of nuclear fuel use, a high conversion ratio was achievedby hardening the neutron spectrum with a tight-lattice core. In TCA, a series of critical experiments were
performed with several different tight-lattice cores. In these experiments, a new nondestructive methodof measuring a new spectral index called the modified conversion ratio was developed to investi gate
spectral changes caused by the tightness of the lattice [4]. Later, this technique was used to measure themodified conversion ratios of a series of fuel lattices in TCA to obtain spectral indices for a wide rangeof spectral changes [5]. Other critical assemblies in Japan and abroad began to measure modified
conversion ratios using the same method, and the results were used as benchmark data for nuclear data.
Almost at this time, the continuous energy Monte Carlo code MVP, which had been underdevelopment at JAERI, was released, allowing as build analysis of critical experiment systems. As aresult, direct verification (benchmarking) of nuclear data using critical experiment data became possible,
and the distance between reactor physics (experiment) and nuclear data (evaluation) seemed to become-66

JAEA-Conf 2023-001

very close. Through benchmark calculations, I also began to participate in the nuclear data evaluation
activities conducted by the Japanese Nuclear Data Committee (JNDC). In this committee activity, I also
participated in the evaluation of the effective delayed neutron fraction (β eff), which is a quantity thatserves as a scale for converting the numerically calculated reactivity (in dk/k) to the experimentally
calculated reactivity (in $). If the value of βeff is inaccurate, a certain deviation (bias) will occur between
the numerical calculation and the experimental value. The TCA reactivity value also show ed a certain
bias from the numerical calculation results. Therefore, we re-evaluated the β eff of TCA [6] and proposeda new value for delayed neutron fraction, which was considered appropriate from the reactor physics side,
together with other experimental data [7]. The result was reflected in the revision of the nuclear datalibrary JENDL (JENDL-3.3). Although there was no tool to calculate β eff in continuous energy at thattime, and the multigroup approximation was necessary, but MVP was later improved, and this problem
was solved.
Besides above experiments, a series of MOX critical experiments conducted in the past at TCA ,which have measured critical mass in the same core geometry for about seven years. Since Pu-241 in
MOX fuel decays to Am-241 with a half-life of about 14 years, this long-term critical experiment data isvaluable for verifying the accuracy of Pu-241 or Am-241 nuclear data. Benchmark evaluations using thiscritical experiment data show a trend of increasing effective multiplication factor (which should beconstant) with time [8] indicating that there is some problem with either (or both) of the above two
nuclides.
This trend was also observed in the MOX critical experiments in France, and is not a bias effect due
to the experimental setup. The latest nuclear data are expected to improve the situation.

3. Use of Nuclear Data at Kyoto University (2003-)
3.1. KUR Core Conversion to LEU
In 2003, I started to work at the Kyoto University Research Reactor Institute (now the Institute forIntegrated Radiation and Nuclear Science). My laboratory has been conducting the nuclear datameasurement using an electron linear accelerator (LINAC) and, it has been also in charge of the safety
management of the Kyoto University Research Reactor, KUR (Fig. 3). At that time, there was a news
report that KUR might be decommissioned due to the problem of its spent fuel treatment. However, it
was later officially decided to continue its operation, and the core would be converted from highly
enriched uranium (HEU) core to low enriched uranium (LEU) one. I was assigned to work on the licensing
process for the conversion of the KUR core.
Changing the fuel enrichment of a reactor means configuring a completely new core, and all
descriptions involving the core (and fuel) must be changed in its safety review. In the low -enriched fueldesign, instead of reducing the fuel enrichment, the fuel concentration is increased by employing thesilicide material, and then the nuclear characteristics, such as critical mass, does not change significantly.
But even so, the impact of the enrichment change cannot be ignored. In addition, the content of the KU R
installation application at that time only partially complied to the safety review guidelines for the watercooled test and research reactors established by the Nuclear Safety Commission. Therefore, the main partof the installation application had to be completely revised.
In this safety review, nuclear characteristics of the new core were evaluated. In this evaluation, theSRAC code system was used as the main calculation code, and JENDL-3.3, the latest nuclear data libraryat that time, was used. As mentioned before, the new value was used for the delayed neutron fraction of-77

JAEA-Conf 2023-001

JENDL-3.3, the calculated result of effective delayed neutron fraction was approximately 10% smaller
than that used in the previous version (highly enriched uranium system, ENDF-B/IV was used for the
nuclear data library). The smaller effective delayed neutron fraction means that the reactivity in $ unit
becomes 10% larger when the reactivity is input in dk/k unit, and as a result, the analytical results ofcontrol rod mis-withdrawal events did not meet the limit value. Therefore, it became necessary to set a
new limit for control rod operation. Although the accuracy was improved by revising the delayed neutron
fraction, I experienced the magnitude of the impact of revising the nuclear data myself.
3.2. LINAC Experiments
As mentioned above, our laboratory has an electron linear accelerator, LINAC, and nuclear data aremeasured using the time-of-flight neutron method. By using LINAC, we have started the project of"Development of Nondestructive Methods Adopted for Integrity Test of Next Generation Nuclear Fuels"with other organizations in 2014 [9]. This project was funded by the Ministry of Education, Culture,
Sports, Science and Technology of Japan (MEXT) for 4 years.
In the nondestructive measurement, we use the neutron resonance absorption reaction of the target
nuclide, and we can identify the nuclide and its concentration in the fuel rod. To obtain the accurate
results, the highly accurate nuclear data are indispensable. If we apply this measurement technique to theadvanced fuel, which will be used to transmute the high-level radioactive waste in fast reactor systems,
accurate nuclear data for various minor actinides and long-lived fission products are required. Therefore,
the improving of the nuclear data library should be continuously carried out.

4. Activities in the Japanese Nuclear Data Committee
When I started experiments on high conversion LWRs (around 1992) using TCA, I was asked to
introduce the experimental data in the Integral Test Working Group (WG) of the Japanese Nuclear Data
Committee (JNDC), which led me to become a member of this WG and to participate in benchmarking
activities for a wide range of critical experiments. Here, we provided experimental data on critical masses
and reaction rate ratios of various core at TCA, and they were used to validate JENDL. In addition to thisWG, there are many other technical subcommittees, WGs, and so on in JNDC. I also participated in someof those groups as follows.
The Delayed Neutron WG was established in 1997 to review delayed neutron data and has been reevaluating the delayed neutron fraction based on experimental data from JAERI's critical assemblies,
FCA (Fast Critical Assembly), TCA, and VHTRC (High Temperature Gas Reactor Critical Assembly) .
The results of the reevaluation are reflected in JENDL-3.3, as mentioned earlier. The WG also considered
a proposal from a U.S. researcher to increase the number of delayed neutron groups to nine, but inconsideration of the impact of this change, it was decided to maintain the existing six groups.
Furthermore, in 2006, the Quality Assurance Study Group was established to examine the quality
assurance of nuclear data, and after about three years of activities, the basic concept of quality assurance
for JENDL was compiled [10]. For JENDL to be widely used internationally in the future, it is necessary
not only to ensure the accuracy of nuclear data and the number of nuclides and reactions, but also toensure the quality assurance of nuclear data, and this activity is a pioneering st ep in this direction.
The Japanese Nuclear Data Committee was initially a generic name for the committee of JAERI andthat of the Atomic Energy Society of Japan (AESJ), called as SIGMA special committee. The activitiesof the above-mentioned technical subcommittees, working groups, etc. were basically supported by-88

JAEA-Conf 2023-001

JAERI. However, after the Japan Atomic Energy Agency (JAEA) was established as the result oforganizational reform of JAEA in 2005, a clear distinction between academic activities and JAEA’s
activity was required, and then the committee independent of the Society was established, which was also
called as JNDC. In 2010, the name of the committee was changed to the current "JENDL Committee"
and has continued its activities.
On the other hand, AESJ’s SIGMA special (ad-hoc) committee, which was established in in 1963,(SIGMA special committee since 1965), has continued its activities to this day as the SIGMA
investigation committee (Investigation Committee on Nuclear Data) since 2019.
I am not an expert in nuclear data as mentioned so far, but since I have been participating in theactivity of JNDC for a long time, I have been chairing the JENDL committee since FY2017. JAEA
released JENDL-5 in December 2021, and since then, we have been conducting data validation anddissemination activities, as well as studying the next revision of JENDL.

5. At the end
I have looked back on some memories that have something to do with nuclear data. Please forgive
me if some of them seem to have nothing to do with nuclear data.
In principle, nuclear data should converge to a single value at some point, but in reality this is not
the case, and nuclear data are reviewed and updated on a daily basis. It is necessary to continue thisactivity to build a nuclear data library with higher accuracy in the future. For this purpose, thedevelopment of research infrastructure and human resources necessary for nuclear data measurement andevaluation are urgent issues.

References[1] Takeshita I. et al., Safety design of the NUCEF critical facilities, Proc. of the 3rd Int. Conf. on
Nuclear Fuel Reprocessing and Waste Management, Sendai, 1991, vol.1, pp.510-515.
[2] Nakajima K. et al., A Kinetics Code for Criticality Accident Analysis of Fissile Solution
Systems: AGNES2, JAERI-Data/Code 2002-004, 2002 [in Japanese].
[3] Tsuruta H. et al., Critical Sizes of Light-Water Moderated UO 2 and PuO2-UO2 Lattices, JAERI
1254, 1978.
[4] Nakajima K. et al., Measurements of the Modified Conversion Ratio by Gamma-Ray
Spectrometry of Fuel Rods for Water-Moderated U02 Cores, Nucl. Sci. Eng., vol.116, 1994,
pp.138-146.
[5] Nakajima K. et al., Modified Conversion Ratio Measurement in Light Water-Moderated UO2Lattices, Nucl. Technol., vol.113, 1996, pp.375-379.
[6] Nakajima K., Re-evaluation of the Effective Delayed Neutron Fraction Measured by the
Substitution Technique for a Light Water Moderated Low-Enriched Uranium Core, J. Nucl. Sci.
Technol., vol.38, no.12, 2001, pp.1120-1125.
[7] Yoshida T., et al., Evaluation of Delayed Neutron Data for JENDL-3.3, J. Nucl. Sci. Technol.,
Supplement 2, 2002, pp.136-139.
[8] Nakajima K., et al., Validation of 241Am Capture Cross Section through Integral Test using
Criticality Data of Light-water Moderated MOX Cores, Energy Procedia, vol.71, 2015, pp.237243.
[9] Nakajima K., Outline of the Development of Nondestructive Methods Adopted for Integrity-99

JAEA-Conf 2023-001

Test of Next Generation Nuclear Fuels (N-DeMAIN), JPS Conf. Proc, vol.24, 011019, 2019,
pp. 1-6. (Proc. 2nd Int. Symp. on Radiation Detectors and Their Uses (ISRD2018))[10] Yamano N., et al., Quality Management System Proposed to JENDL Evaluation Project, J.
Korean Physical Soc., vol.59, no.2, 2011, pp.1298-1302.

Acknowledgements
I would like to thank all the people who have been very helpful to me in the nuclear data-related
activities.

Fig.2 Core tank of TCA
Source:https://www.jaea.go.jp/english/04/ntokai/anzen/anzen_04.html

Fig. 1 Core tank of TRACY
Source:https://rdreview.jaea.go.jp/tayu/ACT96J/
04/0404.htm

Fig.3 Reactor building of KUR- 10 10

JAEA-Conf 2023-001

3.

40-year experience in nuclear data
Satoshi CHIBATokyo Institute of Technology
2-12-1 Ookayama, Meguro, Tokyo 152-8550, Japan*

Email: chiba.s.ae@m.titech.ac.jp

A part of my experiences during my career of about 40 years will be reviewed briefly. I have involved
in researches such as neutron scattering experiments and analysis in terms of dispersive optical model,
analysis of nucleon scattering data by the soft-rotator model, solution of a puzzle in statistical treatmentof nuclear data referred to as “Peelle’s Pertinent Puzzle”, development of JENDL Fusion File and JENDL3, 4 and 5, development of Quantum Molecular Dynamics (QMD), providing nuclear data to
nucleosynthesis such as neutrino cross sections and fission fragment yields, developing surrogate reaction
method with heavy-ion beams, theoretical treatment of nuclear fission with a set of variety of theories tocover the whole process of nuclear fission, development of a transmutation system of LLFP with fast
reactors, and uncertainty qualification based on total Monte-Carlo method. In the reference section,
papers published in scientific and/or engineering journals in my whole career have been listed in the
inversely chronological order [1-214], excluding review articles and proceedings.

1. Introduction
Nuclear data is one of the most fundamental and therefore important fields in research anddevelopment of nuclear energy systems. The field of nuclear data contains actually variety of subjects
such as 1) experimental activities, 2) theoretical activities, 3) statistical analysis including machinelearning, 4) compilation of knowledge and database, 5) evaluation, and 6) benchmark and studies on
impact to reactor properties. I have involved in researches in some of these subjects for almost 40 years.
Some of my recent activities will be briefly reviewed in this manuscript, but, unfortunately not all ofthem.
Nuclear fission, which proceeds as shown in Fig. 1, is the most fundamental physics process underlying
nuclear energy, which is recognized widely as an important source of zero-carbon energy. Nuclear fission
makes the stable operation of nuclear reactors possible through a chain reaction mediated by fission
neutrons, generating heat at the same time due to its huge positive Q-value. Furthermore, nuclear fission
populates a number of radioactive fission products, and the treatment of the radioactive wastes i s one of
the key issues in the utilization of nuclear energy. On the other hand, some of the fission products like
99Tc have been used as important radioactive materials for, e.g., medical applications. Moreover, nuclear
fission takes place in r-process nucleosynthesis in merger events of 2 neutron stars or between a neutronstar and a blackhole, which determines the abundance of medium to heavy nuclei through fission
recycling. Therefore, information on nuclear fission is crucial in accurate design of nucl ear systems,
medical applications and in understanding origin of matter in the cosmos. Recently, it is also pointed outthat antineutrinos emitted by the β- decay of fission products can be used for precise understanding of
the neutrino oscillation, verification of sterile neutrinos, and also for remote monitoring of reactor status
for nuclear safeguards.
Nuclear fission has been studied for more than eighty years since its discovery. However, fundamental- 11 11

JAEA-Conf 2023-001

aspects of nuclear fission still remain to be a mystery due to its sophisticated nature as a large -amplitude
collective motion of systems including finite number of nucleons [16]. Indeed, we still cannot explain thewhole property of nuclear fission even for the n+ 235U reaction with sufficient predictive power, althoughexperimental data and/or empirical models have been applied for practical use. Such practical methods
may work properly in the case of well examined neutron-induce fission of 235U and 239Pu. In order todevelop a new system such as Accelerator-driven Systems (ADS) and Fast Reactors (FR) which may act
also as a transmuter of the TRU wastes, we need high quality nuclear data of minor actinides (MA), which
are fissile or fissionable nuclei. Experiments to obtain fission data for MA and long-lived fission products(LLFP) have been performed in various facilities. However, it is still difficult to cover wide-variety offission data, such as fission fragment mass distributions (FFMDs), total kinetic energy (TKE), number ofprompt and delayed neutrons, decay heat, and emission of antielectron neutrinos from the fission products.
We have developed a comprehensive set of nuclear models which can reproduce and predict the sephysical quantities related to nuclear fission.
In addition to the above fundamental approaches, we have worked also on the reduction of long-lived
fission products, research on the effects of uncertainty of nuclear data on properties of nuclear systems,
and the influence of nuclear data on the clearance problem of decommissioning by developing acomputational scheme of high-quality nuclear data. The aim of my work has been improvement of nuclear
data starting from fundamental researches to application, placing emphasis on fission-related nuclear data.

2. Fundamental studies for nuclear fission
Nuclear fission we consider is initiated byabsorption of neutrons by heavy nuclei like 235U
and 239Pu, the process
in Fig. 1, which can be
described by a standard method like the opticalmodel or the coupled-channels theory.
However, it is still difficult to describe the wholefeature of a nuclear fission process starting at
and after with a single model due to the fact that
nuclear force is still unclear owing to its
complexity as a relativistic many-body problem
consisting of quarks and gluons, as well as a factthat it consists of several parts which havecompletely different time scales ranging from
10-20 second (processto) to
106 years
for process. Indeed, there is no theoreticalmodel which can simulate the whole process of
nuclear fission shown in Fig. 1. Therefore, wehave developed different models depending on
our purpose. We have studied the fundamental
mechanism of nuclear fission at low excitation
Fig. 1 Schematic view of nuclear fission process.
energies with models such as a 4-dimensional
Langevin model, the Anti-symmetrized Molecular Dynamics, relativistic and non-relativistic density
functional theories to describe the process
toin Fig. 1. As a result of this process, about 1,300
different primary fission fragments are formed at stage
even from a single fissioning system, and weneed to specify the yield, distributions of kinetic energy, excitation energy and spin -parity to each of the- 12 12

JAEA-Conf 2023-001

populated fragment, which is a formidable task. Furthermore, we have used the Hauser-Feshbach theory
to describe the statistical decay of the primary fission fragments (process) to lead to the population of
independent fission products and emission of prompt neutrons and-rays, and the gross theory of betadecay and summation method to investigate the final β-decay part (process) which leads to thegeneration of delayed neutrons, decay heat, and emission of anti-electron neutrinos.
2.1. Fission properties studied by the Langevin equation
Langevin dynamical model can reproduce and predict not only the fission fragment mass yields but
also the total kinetic energies of the fission fragments of various actinides very accurately. In the Langevinmodel, a nuclear fission process is regarded as a time-evolution of the nuclear shape of a compound
nucleus, which is formed via neutron absorption by a target in a neutron-induced reaction, following theequation of motion under the friction force and the random force (so called the Langevin equation). The
Langevin equations are formulated as a set of coupled stochastic differential equations. We havedeveloped a 4-dimensinal Langevin model [27, 29, 30] by extending degree of freedom to describe arealistic nuclear-shape leading to nuclear scission, and by introduction of quantal effects to the free energy,
the zero-point energy correction to each of the collective coordinate, and also by introducing microscopictransport coefficients based on the linear response theory [46].
Figure 2 shows calculated mass distributions of fission fragments (black histograms) compared withexperimental data (red circles) at excitation of 20 MeV as representatives of compound nuclei populated
by neutrons. In contrast, Fig. 3 compares calculated mass-TKE correlation of fission fragments (leftpanel) with experimental data (right panel). The gray histogram in the upper-left panel of Fig. 2 shows acalculation without quantal effects yielding only 1-peak in mass distribution. These figures show how
our 4D Langevin model can describe known properties of nuclear fission by taking account of the quantal
effects properly into the thermodynamic approach represented by the Langevin equation. Verified by thisquantitative agreement, we have made a systematic calculation of fragments-mass vs. TKE correlation
for actinides as shown in Fig. 4 [19]. We notice that, starting from the left-bottom to the right-upper panel,
the TKE of the symmetric component makes a sudden jump to higher values at mass number of 250 to
254 which is an indication of transition of the symmetric mode from superlong to sup ershort mode.

Fig. 3 Mass-TKE correlation of fission fragments (left:
our calculation, right: experimental data).
Fig. 2 Calculated mass distribution of fission fragments(black histograms) compared to experimental information(right circles).

- 13 13

JAEA-Conf 2023-001

Furthermore, the dominant mode, shown by red
dots, moves from the asymmetric mode to thesymmetric mode at A=257 to 258, then moves backto the asymmetric mode at 260Md to 256No, making
mass distribution to change from 2-peak structure
to 1-peak, then to 2-peak again. Such a “correlatedtransition” of 2 physical quantities were effective inunderstanding systematical and anomalous trends
in the fission mechanisms of actinide nuclei in a
unified manner.
Then, based on this success, we have extended
our calculation to superheavy nuclei [13]. A resultis shown in Fig. 5 for the fragment-mass vs. TKE
correlation of 294Og (Z=118). We can notice that
this correlation pattern is much more complicatedthan that of the actinide region shown in Figs. 3 and4. We have found that the shell of 208Pb plays adominant role in the fission mechanisms ofsuperheavy nuclei to form the “superaymmetric”
component.

Fig. 4 Mass-TKE correlation of fission fragments fora series of actinide nuclei arranged in increasing orderof Z2/A1/3 of fissioning nucleus starting from theleftmost-bottom to the rightmost upper panel.

2.2. Application of Antisymmetrized Molecular
Dynamics (AMD) to study of nuclear fission
While we understood that Langevin model gives
rather accurate results to describe various propertiesof nuclear fission, it is based on a macroscopic
approach, and it lacks full microscopic descriptionof the fission process, which is becoming a major
trends in this field. Then, we also have investigated
the fission reaction based on the Antisymmetrized
Molecular Dynamics (hereafter AMD). In AMD, anucleus can be microscopically described by aSlater determinant consisting of Gaussian wave Fig. 5 Predicted mass-TKE correlation of fission
packets chosen as variational functions to represent fragments for 294Og at Ex=10 MeV.
single-particle states. AMD has been widely used to
study nuclear reactions and nuclear structures for light nuclei, but we are the only one group to apply
AMD to fission study. From this study, we expect to get aspects of nuclear fission that cannot be obtained
from the Langevin model.
In Fig. 6, we show snapshots of nucleon density distributions during the fission of 236U (= compound
nucleus of n + 235U reaction), where degree-of-freedom of 92 protons and 144 neutrons are explicitly
considered. We have adopted SLy4 effective interaction acting among nucleons, NN collision by LiMachleit parameterization, and the fission was initiated by a technique called “symmetric boost
mechanism”. By repeating such calculations, we can obtain distributions of isotopes, TKE and spin offission fragments.

- 14 -

JAEA-Conf 2023-001

In Fig. 7, we plotted mass-TKE correlation offission fragments originated from 236U
compound nucleus. The color contour shows
data estimated from experimental information,
while circles are the results of AMD Fig. 6 Snapshots of time evolution of nucleon density
calculation, which corresponds to symmetricduring fission of 236U.
fission mode. We notice that the AMD
calculation can describe the TKEs of
symmetric fission components quite accurately.
Through such simulations, we could draw
conclusions on the spin distribution andmechanisms of ternary fission in quantitative
manner.
2.3 Relativistic and non-relativistic density
functional theories
Other microscopic approaches used in ourlaboratory are relativistic and non-relativistic
Fig. 7 Fragment mass-TKE correlation of 236U.
density functional theories. These models canColor contour: experimental data, white circles:
provide detailed information on potential energy
AMD calculation.
surfaces as a function of nuclear deformations
and on fission barrier height. Nevertheless, there
is no effective interaction designed for nuclear fission itself. In our laboratory, we have investigated how
the pairing interaction affects the fission barrier height in both models, and found that about 20% increasein the pairing strength drastically improves reproduction of fission barrier heights [3,5,7]. Our study on
the pairing interaction is based on a consideration including the pairing rotational energy, which confirms
the validity of our conclusions. Furthermore, we found that triaxiality has a dominant role in the heightof outer fission barrier.

3. Beta decay of fission products [22, 33, 42]
After prompt neutrons and gammas emitted from the fission fragments, the beta-decays of these nuclei
will occur. Anti-electron neutrinos (abbreviated as neutrinos for simplicity) produced by the beta -decay
process play a significant role in the surveillance and in-service inspection of nuclear power plants, which
can serve as a novel method of nuclear safeguards. They are also used to establish neutrino oscillations,and such a study eventually leads to discovery of exotic particles such as sterile neutrino s.
We have studied the antineutrino spectrum from aggregate beta-decay of fission products based onsummation calculation and the gross theory. Figure 8 shows a comparison of antineutrino spectra emitted
from β-decay of 92Rb calculated by Gross Theory 2 (red line) and experimental data (triangles). We
have performed such calculations for about 1,000 FP nuclei, and constructed an original database. Then,
Fig. 9 compares aggregate and independent antineutrino spectra emitted from fission products populated
in the fission of thermal neutron + 235U system. The aggregate spectra are made by superposition of about
1,000 fission products. The calculation was done by using JENDL Decay Data Library 2011 and FPY(Fission Product Yield) from FPY2011 and that in JENDL-5 (FPY2020). We notice that the differenceof the FPY data makes a difference in the neutrino spectra above 8 MeV, where only several nuclei like
92,95Rb and 96Y, having large Q
β values, contribute. Even though the calculation seems to reproduce the- 15 15

JAEA-Conf 2023-001

measured data, the accuracy of such a computational method must be further improved for practicalapplications. Anyhow, we have established the basis of such a computational method.
Antineutrino spectra (fission-1 MeV-1)

100

10-1

10-2

10-3

10-4

10-5

10-6

10-7

10-8
0
2

92

Rb

4
8
98

Y
95

10

Rb

U

235
- FPY2011- FPY2020
Schreckenbach et al.

6

Antineutrino energy (MeV)

Fig. 9 Aggregate and independent neutrino spectra
Fig. 8 Comparison of antineutrino energy spectra emitted from fission products populated in fission of nemitted from β-decay of 92Rb calculated by Gross + 235U system. The triangles are experimental data,
Theory 2 (red line) and experimental data (triangles). while the total and independent neutrino spectra areshown by lines.

4. Evaluation of nuclear data and its impact on integral system
4.1. Development of fission yield data library for various applications
High precision nuclear data on the fission product yield (FPY) is necessary to evaluate the inventoryof radioactive materials in spent nuclear fuel, total decay heat from the fission products and their toxicity.
Historically, FPY data in JENDL have been borrowed from U.S. evaluation ENDF. Fortunately, a numberof measurements of fission product yields (FPYs) have been accumulated since the last major evaluation
was performed in ENDF library.
We have developed a FPY library based on the original evaluation method of experimental data, guided
by all the fundamental research on nuclear fission we have carried out [24]. Our FPY library contains not
only yields such as independent yields and cumulative yields, but also the covariance informat ion on
uncertainty in each data. Recently, such covariance data has been necessitated significantly for V&V(Validation and Verification) purposes. To develop the new library, we first gathered and evaluatedexperimental data from EXFOR database, and then developed a semi-phenomenological FPY model
based on the recent knowledge of the shell effects including the even -odd staggering. The semiphenomenological model is necessary to estimate the FPYs where no measured data exist. Hauser Fechbach theory [28] was also applied to estimate unknown isomer ratios. The covariance was obtainedby a generalized least-squares analysis containing minimal physics constraints. In this manner, weconstructed a brand-new FPY library for the first time in Japan [12]. Our FPY library was adopted in
JENDL-5 as a national nuclear database.
4.2. Impact of uncertainty of nuclear data on integral system
The uncertainty in various quantities relating to nuclear reactors becomes necessary information.
Especially, the uncertainty in the evaluation for radioactivity due to neutron irradiation is strongly- 16 16

JAEA-Conf 2023-001

required by nuclear regulation procedures.
We have evaluated the uncertainty of the cross sections of some LLFP nuclides in JENDL-4.0 by use
of T6 code which evaluates the nuclear data employing the Bayesian Monte Carlo calculations [14]. Using
these methods, we have investigated the uncertainty of the neutron spectra after deep penetration andfound that the correlation of the total cross section and forward elastic angular distribution plays a crucialrole [9].
Acknowledgment
I appreciate all my collaborators. Unfortunately, not all my activities could not be covered in thismanuscript. Here, I wish to post summaries of them taken from Google Scholar citations andResearchGate:
Google Scholar citations:
https://scholar.google.com/citations?hl=en&user=bBpCh60AAAAJ&view_op=list_works&sortby=pubdate
ResearchGate: https://www.researchgate.net/profile/Satoshi-Chiba/stats
I hope this field will evolve steadily in the future.

References
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Taiki Kouno, Chikako Ishizuka, Kazuki Fujio, Tsunenori Inakura, Satoshi Chiba. "Effects oftriaxiality and pairing interaction on fission barriers of actinide nuclei", International Journal ofModern Physics E, 2250080, Sep 2022.
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Naoki Yamano, Tsunenori Inakura, Chikako Ishizuka, Satoshi Chiba. "Crucial importance ofcorrelation between cross sections and angular distributions in nuclear data of 28Si on estimation of
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10) Kazuya Shimada, Chikako Ishizuka, Fedir Ivanyuk, Satoshi Chiba. "Dependence of total kinetic
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13) C. Ishizuka, X. Zhang, M. D. Usang, F. A. Ivanyuk, S. Chiba. "Effect of the doubly magic shellclosures in 132Sn and 208Pb on the mass distributions of fission fragments of superheavy nuclei",
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14) Naoki Yamano, Tsunenori Inakura, Chikako Ishizuka, Satoshi Chiba. "Estimation of uncertainty intransmutation rates of LLFPs in a fast reactor transmutation system via an estimation of the crosssection covariances", Journal of Nuclear Science and Technology, Vol. 58, No. 5, pp. 567-578, Taylor& Francis, Nov 2020.
15) Heamin Ko, Myung-Ki Cheoun, Eunja Ha, Motohiko Kusakabe, Takehito Hayakawa, Hirokazu
Sasaki, Toshitaka Kajino, Masa-aki Hashimoto, Masaomi Ono, Mark D. Usang, Satoshi Chiba, Ko
Nakamura, Alexey Tolstov, Ken'ichi Nomoto, Toshihiko Kawano, Grant J. Mathews. "Neutrino
Process in Core-collapse Supernovae with Neutrino Self-interaction and MSW Effects", The
Astrophysical Journal Letters, Vol. 891, Mar 2020.
16) Michael Bender, Remi Bernard, George Bertsch, Satoshi Chiba, Jacek Dobaczewski, Noel Dubray,
Samuel A. Giuliani, Kouichi Hagino, Denis Lacroix, Zhipan Li, Piotr Magierski, Joachim Maruhn,
Witold Nazarewicz, Junchen Pei, Sophie Peru, Nathalie Pillet, Jorgen Randrup, David Regnier, PaulGerhard Reinhard, Luis M. Robledo, Wouter Ryssens, Jhilam Sadhukhan, Guillaume Scamps,
Nicolas Schunck, Cedric Simenel, Janusz Skalski, Ionel Stetcu, Paul Stevenson, Sait Umar, Marc
Verriere, Dario Vretenar, Michaa Warda, Sven Aberg. "Future of Nuclear Fission Theory", Journalof Physics G: Nuclear and Particle Physics, Vol. 47, No. 11, 113002, Oct 2020.
17) Toshio Wakabayashi, Makoto Takahashi, Satoshi Chiba, Naoyuki Takaki, Yoshiaki Tachi. "A fast
reactor transmutation system for 6 LLFP nuclides", Nuclear Engineering and Design, Vol. 363,
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18) Toshio Wakabayashi, Yoshiaki Tachi, Makoto Takahashi, Satoshi Chiba, Naoyuki Takaki. "Study on
method to achieve high transmutation of LLFP using fast reactor", Scientific Reports, 9, 19156(2019), Dec 2019.
19) Mark Dennis Usang, Fedir A. Ivanyuk, Chikako Ishizuka, Satoshi Chiba. "Correlated transitions in
TKE and mass distributions of fission fragments described by 4-D Langevin equation", Scientific- 18 18

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Reports, Vol. 9, Page 1525, Springer Nature, Feb 2019.
20) K. R. Kean, K. Nishio, K. Hirose, M. J. Vermeulen, H. Makii, R. Orlandi, K. Tsukada, A. N.
Andreyev, I. Tsekhanovich, S. Chiba. "Validation of the multinucleon transfer method for thedetermination of the fission barrier height", Physical Review C, Vol. 100, 014611, Jul 2019.
21) V. L. Litnevsky, F. A. Ivanyuk, G. I. Kosenko, S. Chiba. "Description of the mass-asymmetric fissionof the Pt isotopes, obtained in the reaction 36Ar+142Nd within the two-stage fusion-fission model",Physical Review C, Vol. 99, 054624, May 2019.
22) Tadashi Yoshida, Takahiro Tachibana, Shin Okumura, Satoshi Chiba. "Spectral anomaly of reactor
antineutrinos based on theoretical energy spectra", Physical Review C, Vol. 98, 041303(R), Oct 2018.
23) Yuma Kikuchi, Kazuyuki Ogata, Takehito Hayakawa, Satoshi Chiba. "Azimuthal angle distributionsof neutrons emitted from the 9Be(γ, n) reaction", Physical Review C, Vol. 98, Dec 2018.
24) Takehito Hayakawa, Heamin Ko, Myung-Ki Cheoun, Motohiko Kusakabe, Toshitaka Kajino, MarkD. Usang, Satoshi Chiba, Ko Nakamura, Alexey Tolstov, Ken’ichi Nomoto, Masa-aki Hashimoto,
Masaomi Ono, Toshihiko Kawano, Grant J. Mathews. "Short-Lived Radioisotope 98Tc Synthesized
by the Supernova Neutrino Process", Physical Review Letters, vol. 121, page 102701, Sep 2018.
25) F.A. Ivanyuk, C. Ishizuka, M.D. Usang, S. Chiba. "The 4-dimensional Langevin approach to low
energy nuclear fission", EPJ Web of Conferences, vol. 169, page 00005, Mar 2018.
26) Toshio Suzuki, Satoshi Chiba, Takashi Yoshida, Koh Takahashi, Hideyuki Umeda. "Neutrino nucleus reactions on 16O based on new shell-model Hamiltonians", Physical Review C, Vol. 98, Page
034613, Sep 2018.
27) Fedir A. Ivanyuk, C. Ishizuka, M.D. Usang, S. Chiba. "Temperature dependence of shell corrections",
Phys. Rev. C, vol. 97, page 054331, May 2018.
28) Shin Okumura, Toshihiko Kawano, Patrick Jaffke, Patrick Talou, Satoshi Chiba. " 235U(n,f)
Independent Fission Product Yield and Isomeric Ratio Calculated with the Statistical HauserFeshbach Theory", Journal of Nuclear Science and Technology, Volume 55, Issue 9, pp. 1009 -1023,
Taylor & Francis, Jun 2018.
29) M. D. Usang, F. A. Ivanyuk, C. Ishizuka, S. Chiba. "Analysis of the total kinetic energy of fission
fragments with the Langevin equation", Phys. Rev. C, vol. 96, page 064617-1-13, Dec 2017.
30) Chikako Ishizuka, Mark D. Usang, Fedir A. Ivanyuk, Joachim A. Maruhn, Katsuhisa Nishio, Satoshi
Chiba. "Four-dimensional Langevin approach to low-energy nuclear fission of 236U", PhysicalReview C - Nuclear Physics, Volume 96, 6, 064616, Dec 2017.
31) K. Hirose, K. Nishio, S. Tanaka, R. L´eguillon, H. Makii, I. Nishinaka, R. Orlandi, K. Tsukada, J.
Smallcombe, M. J. Vermeulen, S. Chiba, Y. Aritomo, T. Ohtsuki, K. Nakano, S. Araki, Y. Watanabe,
R. Tatsuzawa, N. Takaki, N. Tamura, S. Goto, I. Tsekhanovich, A. N. Andreyev. "Role ofMultichance Fission in the Description of Fission-Fragment Mass Distributions at High Energies",
Phys. Rev. Lett, vol. 119, 222501, Nov 2017.
32) C. Ishizuka, S. Chiba, N. Carjan. "Charge polarization and the elongation of the fissioning nucleus
at scission", Romanian Reports in Physics, vol. 70, page 202, Sep 2017.
33) Hiroyuki Koura, Satoshi Chiba. "Improvement to the gross theory of β decay by inclusion of change
in parity", Physical Review C, vol. 95, 064304-1-6, Jun 2017.
34) Rei Kimura, Hiroshi Sagara, Satoshi Chiba. "Applicability Study of the Photofission Based Nuclear
Material Isotopic Composition Measurement Method on the Thorium Uranium System", Energy
Procedia, pp. 264-273, Dec 2017.

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35) D.S. Martyanov, E.Sh. Soukhovitski˜ı, R. Capote, J.M. Quesada, S. Chiba. "Predicting the opticalobservables for nucleon scattering on even-even actinides", Chinese Physics C, Vol. 41, No. 9,094105-1-6, Sep 2017.
36) Usang, M.D., Ivanyuk, F., Chikako Ishizuka, Satoshi Chiba. "Systematic Analysis of Fission
Fragment Mass Distribution and TKE for Actinides by Langevin Equation", Energy Procedia, Vol.
131, pp. 299-305, 2017.
37) Satoshi Chiba, Toshio Wakabayashi, Yoshiaki Tachi, Naoyuki Takaki, Atsunori Terashima, Shin
Okumura, Tadashi Yoshida. "Method to Reduce Long-lived Fission Products by Nuclear
Transmutations with Fast Spectrum Reactors", Scientific Reports, Vol. 7, Springer Nature, Oct 2017.
38) Chikako Ishizuka, Hiroki Jojima, Mark D. Usang, Satoshi Chiba, Nicolae Carjan. "The chargepolarization and its impact on prompt fission neutron multiplicity", Energy Procedia, Vol. 131, pp.
285-291, Dec 2017.
39) Kentaro Hirose, K. Nishio, Hiroyuki Makii, Ichiro Nishinaka, S. Ota, T. Nagayama, N. Tamura, S.
Goto, A.N. Andreyev, M.J. Vermeulen, S. Gilespie, C. Barton, A. Kimura, H. Harada, S. Meigo, S.
Chiba, T. Ohtsuki. "Simultaneous measurement of neutron-induced fission and capture cross sectionsfor 241Am at neutron energies below", Nuclear Instruments and Methods in Physics Research Section
A, vol. 856, pp. 133-138, 2017.
40) E. Sh. Soukhovitski, R. Capote, J. M. Quesada, S. Chiba, D. S. Martyanov. "Nucleon scattering on
actinides using a dispersive optical model with extended couplings", Physical Review C, Vol. 94,
064605, Dec 2016.
41) Tanaka, K.-I., Ueno, J., Satoshi Chiba. "Estimation of a boundary to distinguish between radioactive
materials and non-radioactive materials around a Main Steam line and a Feed Water line in a
Biological Shielding Wall of a BWR for decommissioning", Progress in Nuclear Energy, Vol. 93, pp.
371-385, 2016.
42) Tadashi Yoshida, Takahiro Tachibana, Naoto Hagura, Satoshi Chiba. "Composition, decomposition
and analysis of reactor antineutrino and electron spectra based on gross theory of β-decay andsummation method", Progress in Nuclear Energy, Vol. 88, pp. 175-182, Apr 2016.
43) Rei Kimura, Hiroshi Sagara, Satoshi Chiba. "Principle validation of nuclear fuel material isotopic
composition measurement method based on photofission reactions", Journal of Nuclear Science andTechnology, Vol. 53, Issue 12, pp. 1978-1987, May 2016.
44) R. Léguillon, K. Nishio, K. Hirose, H. Makii, I. Nishinaka, R. Orlandi, K. Tsukada, J. Smallcombe,
S. Chiba, Y. Aritomo, T. Ohtsuki, R. Tatsuzawa, N. Takaki, N. Tamura, S. Goto, I. Tsekhanovich, C.
M. Petrache, A. N. Andreyev. "Fission fragments mass distributions of nuclei populated by themultinucleon transfer channels of the 18O + 232Th reaction", Physics Letters B, Vol. 761, pp. 125130, Oct 2016.
45) D. Ichinkhorloo, M. Aikawa, S. Chiba, Y. Hirabayashi, K. Katō. "Low energy scattering crosssections for n + 6,7Li reactions using the continuum-discretized coupled-channels method", PhysicalReview C, Vol. 93, 064612, Jun 2016.
46) M. D. Usang, F. A. Ivanyuk, C. Ishizuka, S. Chiba. "Effects of microscopic transport coefficien ts on
fission observables calculated by the Langevin equation", Physical Review C, Vol. 94, No. 4, Page
044602, Oct 2016.
47) T. Hayakawa, T. Shizuma, S. Miyamoto, S. Amano, A. Takemoto, M. Yamaguchi, K. Horikawa, H.
Akimune, S. Chiba, K. Ogata, M. Fujiwara. "Spatial anisotropy of neutrons emitted from the- 20 -

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56

Fe(γ,n)55Fe reaction with a linearly polarized γ-ray beam", Physical Review C, Vol. 93, 044313,

Apr 2016.
48) Takehito Hayakawa, Shuji Miyamoto, Takayasu Mochizuki, Ken Horikawa, Sho Amano, Dazhi Li,
Kazuo Imazaki, Yasukazu Izawa, Kazuyuki Ogata, Satoshi Chiba. "Laser Compton Scattering
Gamma-Ray Experiments for Supernova Neutrino Process", Plasma and Fusion Research, Vol. 11,
Page 3406066, Jun 2016.
49) T. Hayakawa, Y. Toh, M. Huang, T. Shizuma, A. Kimura, S. Nakamura, H. Harada, N. Iwamoto, S.
Chiba, T. Kajino. "Measurement of the isomer production ratio for the 112Cd(n, γ)113Cd reaction using
neutron beams at J-PARC", Physical Review C, Vol. 94, No. 5, 055803, Nov 2016.
50) S. Shibagaki, T. Kajino, G. J. Mathews, S. Chiba, S. Nishimura, G. Lorusso. "Relative contributionsof the weak, main and fission-recycling r-process", The Astrophysical journal, Vol. 816, No. 2, Jan
2016.
51) R. Capote, N. Carjan, S. Chiba. "Scission neutrons for U, Pu, Cm, and Cf isotopes: Relative
multiplicities calculated in the sudden limit", Physical Review C, Vol. 93, 024609, Feb 2016.
52) T. Sato, K. Niita, N. Matsuda, S. Hashimoto, Y. Iwamoto, T. Furuta, S. Noda, T. Ogawa, H. Iwase,
H. Nakashima, T. Fukahori, K. Okumura, T. Kai, S. Chiba, L. Sihver. "Overview of particle andheavy ion transport code system PHITS", Annals of Nuclear Energy, Vol. 82, pp. 110-115, Aug 2015.
53) Koura, H., Satoshi Chiba. "Theoretical Study of Beta Decay for Delayed Neutron", Energy Procedia,
Vol. 71, pp. 228-236, 2015.
54) H. Makii, S. Ota, T. Ishii, Y. Wakabayashi, K. Furutaka, K. Nishio, I. Nishinaka, S.Chiba, M. Igashira,A. Czeszumska. "Development of a measurement system for the determination of (n, γ) crosssections using multi-nucleon transfer reactions", Nuclear Instruments and Methods in Physics
Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 797, pp.
83-93, Oct 2015.
55) Ken-ichi Tanaka, Jun Ueno, Masataka Adachi, Satoshi Chiba. "Improvement of a calculation
procedure of neutron-flux distribution for radioactivity inventory estimation for decommissioningof nuclear power plants", Progress in Nuclear Energy, Vol. 85, pp. 254-270, Nov 2015.
56) Satoshi Chiba, Nishio, K., Aritomo, Y., Koura, H., Iwamoto, O., Kugo, T., "A Comprehensive
Approach to Estimate Delayed-neutron Data of Actinides and Minor-actinides", Energy Procedia,
Vol. 71, pp. 205-212, 2015.
57) Yoshihiro Aritomo, Satoshi Chiba, Katsuhisa Nishio. "Independent fission yields studied based on
Langevin equation", Progress in Nuclear Energy, Vol. 85, pp. 568-572, Nov 2015.
58) Fedir Ivanyuk, Satoshi Chiba, Yoshihiro Aritomo. "The transport coefficient of collective motion
within the two-center shell model shape parameterization", Journal of Nuclear Science andTechnology, Vol. 53, 6, pp. 737-748, Aug 2015.
59) Toshiki Maruyama, Toshitaka Tatsumi, Dmitri N. Voskresensky, Tomonori Tanigawa, Satoshi Chiba.
"Nuclear “pasta” structures and the charge screening effect", Physical Review C - Nuclear Physics,
Vol. 72, 015802, Jul 2005.
60) K. Horikawa, S. Miyamoto, T. Mochizuki, S. Amano, D. Li, K. Imasaki, Y. Izawa, K. Ogata, S. Chiba,
T. Hayakawa. "Neutron angular distribution in (γ, n) reactions with linearly polarized γ-ray beam
generated by laser Compton scattering", Physics Letters B, Vol. 737, pp. 109-113, Oct 2014.
61) Yuji Fukaya, Minoru Goto, Hirofumi Ohashi, Yukio Tachibana, Kazuhiko Kunitomi, Satoshi Chiba.
"Proposal of a plutonium burner system based on HTGR with high proliferation resistance", Journal- 21 -

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of Nuclear Science and Technology, Vol. 51, 6, pp. 818-831, Apr 2014.
62) Shusaku Noda, Shintaro Hashimoto, Tatsuhiko Sato, Tokio Fukahori, Satoshi Chiba, Koji Niita.
"Improvement of photonuclear reaction model below 140 MeV in the PHITS code", Journal of
Nuclear Science and Technology, Vol. 52, 1, pp. 57-62, Jun 2014.
63) S. Chiba, K. Nishio, H. Makii, Y. Aritomo, I. Nishinaka, T. Ishii, K. Tsukada, M. Asai, K. Furutaka,
S. Hashimoto, H. Koura, K. Ogata, T. Otsuki, T. Nagayama. "Surrogate Reactions Research at
JAEA/Tokyo Tech", Nuclear Data Sheets, Vol. 119, pp. 229-232, May 2014.
64) Y. Aritomo, S. Chiba, F. Ivanyuk. "Fission dynamics at low excitation energy", Physical Review C,
Vol. 90, 054609, Nov 2014.
65) F. A. Ivanyuk, S. Chiba, Y. Aritomo. "Scission-point configuration within the two-center shell model
shape parameterization", Physical Review C, Vol. 90, 054607, Nov 2014.
66) H. Makii, S. Ota, T. Ishii, K. Nishio, I. Nishinaka, K. Furutaka, Y. Wakabayashi, S. Chiba, M.
Igashira. "Development of Anti-Compton LaBr3(Ce) Spectrometer for Measurement of Surrogate
Reactions", NUCLEAR DATA SHEETS, Vol. 119, pp. 361-364, May 2014.
67) J.M. Quesada, R. Capote, E.Sh. Soukhovitskij, S. Chiba. "Rotational-vibrational Description of
Nucleon Scattering on Actinide Nuclei Using a Dispersive Coupled-channel Optical Model",Nuclear Data Sheets, Vol. 118, Page 270-272, Apr 2014.
68) Tatsuhiko Sato, Koji Niita, Norihiro Matsuda, Shintaro Hashimoto, Yosuke Iwamoto, Shusaku Noda,
Hiroshi Iwase, Hiroshi Nakashima, Tokio Fukahori, Satoshi Chiba, Lembit Sihver. "Overview of the
PHITS code and its application to medical physics", Progress in Nuclear Science and Technology,
Vol. 4, pp. 879-882, 2014.
69) Hiroyuki Koura, Satoshi Chiba. "Single-Particle Levels of Spherical Nuclei in the Superheavy andExtremely Superheavy Mass Region", Journal of the Physical Society of Japan, Vol. 82, No. 1, 2013.
70) Tatsuhiko Sato, Koji Niita, Norihiro Matsuda, Shintaro Hashimoto, Yosuke Iwamoto, Shusaku Noda,
Tatsuhiko Ogawa, Hiroshi Iwase, Hiroshi Nakashima, Tokio Fukahori, Keisuke Okumura, Tetsuya
Kai, Satoshi Chiba, Takuya Furuta, Lembit Sihver. "Particle and Heavy Ion Transport code System,PHITS, version 2.52", Journal of Nuclear Science and Technology, Vol. 50, No. 9, Jul 2013.
71) Y. Aritomo, S. Chiba. "Fission process of low excited nuclei with Langevin approach", PHYSICALREVIEW C, 88, 044614, Oct 2013.
72) T. Hayakawa, K. Nakamura, T. Kajino, S. Chiba, N. Iwamoto, M. K. Cheoun, G. J. Mathews.
"Supernova neutrino nucleosynthesis of the radioactive 92Nb observed in primitive meteorites", The
Astrophysical Journal, 779, 1, L9-1-5, Dec 2013.
73) S. Hashimoto, K. Niita, N. Matsuda, Y. Iwamoto, H. Iwase, T. Sato, S. Noda, T. Ogawa, H.
Nakashima, T. Fukahori, T. Furuta, S. Chiba, "Features of PHITS and its Application to Medical
Physics", Japanese Journal of Medical Physics (Igakubutsuri), Vol. 33, No. 2, pp. 88–95,2013.
74) Y. Aritomo, K. Hagino, K. Nishio, S. Chiba. "Dynamical approach to heavy-ion induced fission
using actinide target nuclei at energies around the Coulomb barrier", Physical Review C - Nuclear
Physics, Vol. 85, No. 4, Apr 2012.
75) D. Ichinkhorloo, Y. Hirabayashi, K. Kato, M. Aikawa, T. Matsumoto, S. Chiba. "Analysis of 7Li(n,n')7Li* reactions using the continuum-discretized coupled-channels method", Physical Review C,
Vol. 86, 064604, Dec 2012.
76) Myung-Ki Cheoun, Eunja Ha, T. Hayakawa, Satoshi Chiba, Ko Nakamura, Toshitaka Kajino, Grant
J. Mathews. "Neutrino induced reactions for -process nucleosynthesis of 92Nb and 98Tc", Physical- 22 22

JAEA-Conf 2023-001

Review C, Vol. 85, No. 6, 065807, American Physical Society, Jun 2012.
77) D. Ichinkhorloo, Y. Hirabayashi, K. Kato, M. Aikawa, T. Matsumoto, S. Chiba. "Analysis of
7Li(n,n′)7Li* reactions using the continuum-discretized coupled-channels method", PhysicalReview C - Nuclear Physics, Vol. 86, No. 6, 2012.
78) Toshiki Maruyama, Gentaro Watanabe, S. Chiba. "Molecular Dynamics for Dense Matter", Prog.
Theor. Exp. Phys., 01A201, 1-27, 2012.
79) T. Matsumoto, D. Ichinkhorloo, Y. Hirabayashi, K. Katō, S. Chiba. "Systematic description of 6Li(n,n')6Li* → d + α reactions with the microscopic coupled-channels method", Physical Review C, Vol.
83, 064611, Jun 2011.
80) S. Oryu, Y. Hiratsuka, S. Nishinohara, S. Chiba. "Proton-proton phase shifts calculations in
momentum space by a rigorous Coulomb treatment", Journal of Physics G: Nuclear and Particle
Physics, Vol. 39, No. 4, pp. 0451011 - 04510112, Feb 2012.
81) Keiichi Shibata, Osamu Iwamoto, Tsuneo Nakagawa, Nobuyuki Iwamoto, Akira Ichihara, Satoshi
Kunieda, Satoshi Chiba, Kazuyoshi Furutaka, Naohiko Otuka, Takaaki Ohsawa, Toru Murata,
Hiroyuki Matsunobu, Atsushi Zukeran, So Kamada, Jun-ichi Katakura. "JENDL-4.0: A New Libraryfor Nuclear Science and Engineering", Journal of Nuclear Science and Technology, Vol. 48, 1, pp.
1-30, 2011.
82) Kazuyuki OGATA, Shintaro HASHIMOTO, Satoshi CHIBA. "Three-Body Model Calculation of
Spin Distribution in Two-Nucleon Transfer Reaction for the System of 238U(18O,16O)240U Reaction",
Journal of Nuclear Science and Technology, Vol. 48, No. 10, pp. 1337-1342, Jan 2011.
83) Dagvadorj ICHINKHORLOO, Takuma MATSUMOTO, Yoshiharu HIRABAYASHI, Kiyoshi KATO,
Satoshi CHIBA. "Analysis of n + 6Li Reactions Using the Continuum-Discretized Coupled-Channels
Method", Journal of Nuclear Science and Technology, Vol. 48, No. 11, pp. 1357-1360, Nov 2011.
84) Shintaro Hashimoto, Masanobu Yahiro, Kazuyuki Ogata, Kosho Minomo, Satoshi Chiba. "Effective
radii of deuteron induced reactions", Physical Review C, Vol. 83, No. 5, 054617, Apr 2011.
85) Yutaka Utsuno, Satoshi Chiba. "Multiparticle-multihole states around 16O and correlation-energy
effect on the shell gap", Physical Review C - Nuclear Physics, Vol. 83, 021301(R), Feb 2011.
86) Satoshi Chiba, Osamu Iwamoto, Yoshihiro Aritomo. "Spin-dependent observables in surrogate
reactions", Physical Review C, Vol. 84, 054602, Nov 2011.
87) F. Minato, S. Chiba. "Fission barrier of actinide nuclei with double-Λ particles within the Skyrme–
Hartree–Fock method", Nuclear Physics A, Vol. 856, 1, Apr 2011.
88) T. Matsumoto, D. Ichinkhorloo, Y. Hirabayashi, K. Katō, S. Chiba. "Systematic description of
6Li(n,n')dα reactions with the microscopic coupled-channels method", Physical Review C - Nuclear
Physics, Vol. 83, 064611, Jun 2011.
89) Y. Aritomo, S. Chiba, K. Nishio. "Dynamical model of surrogate reactions", Physical Review C Nuclear Physics, Vol. 84, No. 2, pp. 024602, American Physical Society, Aug 2011.
90) T. Hayakawa, T. Kajino, S. Chiba, G. J. Mathews. "New estimate for the time-dependent thermal
nucleosynthesis of 180Tam", Physical Review C - Nuclear Physics, Vol. 81, 5, 052801(R), May 2010.
91) T. Hayakawa, P. Mohr, T Kajino, S. Chiba, G. J. Mathews. "Re-analysis of the (J= 5) state at 592
keV in 180Ta and its role in the ν-process nucleosynthesis of 180Ta in supernovae", Physical Review
C - Nuclear Physics, Vol. 82, 058801, Nov 2010.
92) Toshiki Maruyama, Toshitaka Tatsumi, Satoshi Chiba. "Liquid-gas phase transition in asymmetricnuclear matter at finite temperature", Nuclear Physics A, Vol. 834, 1-4, 561c-563c, Mar 2010.

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93) Myung-Ki Cheoun, Eunja Ha, T. Hayakawa, Toshitaka Kajino, Satoshi Chiba. "Neutrino reactionson

138

La and180

Ta via charged and neutral currents by the quasiparticle random-phaseapproximation", Physical Review C - Nuclear Physics, Vol. 82, 035504, Sep 2010.
94) Satoshi Chiba, Osamu Iwamoto. "Verification of the Surrogate Ratio Method", Physical Review C Nuclear Physics, Vol. 81, 044604, Apr 2010.
95) Osamu Iwamoto, Tsuneo Nakagawa, Naohiko Otuka, Satoshi Chiba, Keisuke Okumura, Go Chiba,
Takaaki Ohsawa, Kazuyoshi Furutaka. "JENDL Actinoid File 2008", Journal of Nuclear Science andTechnology, Vol. 46, 5, pp. 510-528, 2009.
96) Satoshi Kunieda, Satoshi Chiba, Keiichi Shibata, Akira Ichihara, Osamu Iwamoto, Nobuyuki
Iwamoto, Tokio Fukahori, Efrem Sh. SukhovitskiĨ. "Extensive Study of the Soft-Rotator Model
Hamiltonian Parameters for Medium and Heavy Even-Even Nuclei", Journal of Nuclear Science andTechnology, Vol. 46, No. 9, pp. 914-924, 2009.
97) Jeong-Yeon Lee, Insik Hahn, Yeongduk Kim, Seung-Woo Hong, Satoshi Chiba, Efrem Sh.
Soukhovitskii. "Optical potentials for nuclear level structures and nucleon interactions data of tin
isotopes based on the soft-rotator model", Physical Review C - Nuclear Physics, Vol. 79, 064612,
Jun 2009.
98) F. Minato, S. Chiba, K. Hagino. "Fission of heavy Λ hypernuclei with the Skyrme–Hartree–Fockapproach", Nuclear Physics A, Vol. 831, 3-4, pp. 150-162, Dec 2009.
99) Shintaro Hashimoto, Kazuyuki Ogata, Satoshi Chiba, Masanobu Yahiro. "New Approach for
Evaluating Incomplete and Complete Fusion Cross Sections with", Progress of Theoretical Physics,
Vol. 122, 5, pp. 1291–1300, Nov 2009.
100) Toshio Suzuki, Satoshi Chiba, Takashi Yoshida, Koji Higashiyama, Michio Honma, Toshitaka
Kajino, Takaharu Otsuka. "Neutrino-nucleus reactions based on recent advances in shell-model
calcuations", Nuclear Physics A, Vol. 805, pp. 579-581, 2008.
101) S. Chiba, H. Koura, T. Hayakawa, T. Maruyama, T. Kawano, T. Kajino. "Direct and semi -direct
capture in low-energy ( n , γ ) reactions of neutron-rich tin isotopes and its implications for r process nucleosynthesis", Physical Review C - Nuclear Physics, Vol. 77, 015809, Jan 2008.
102) M. Ohta, S. Tatsuda, K. Yamamoto, T. Asano, T. Wada, K. Hashizume, K. Sumiyoshi, K. Otsuki, T.
Kajino, H. Koura, S. Chiba, T. Tachibana. "Systematic study for the shell effect in the fission
fragment mass distribution ruptured from neutron rich nuclei", Nuclear Physics A, Vol. 805, pp. 558560, 2008.
103) Tao Ye, Yukinobu Watanabe, Kazuyuki Ogata, Satoshi Chiba. "Analysis of deuteron elastic
scattering from 6,7Li using the continuum discretized coupled channels method", Physical Review C- Nuclear Physics, Vol. 78, 024611, Aug 2008.
104) Toshiki Maruyama, Satoshi Chiba, Hans-Josef Schulze, Toshitaka Tatsumi. "Quark deconfinementtransition in hyperonic matter", Physics Letters B, Vol. 659, 1-2, Jan 2008.
105) R. Capote, S. Chiba, E. Sh. Soukhovitskiĩ, J. M. Quesada, E. Bauge. "A Global Dispersive CoupledChannel Optical Model Potential for Actinides", Journal of Nuclear Science and Technology, Vol.
45, 4, 333-340, 2008.
106) Takashi Yoshida, Toshio Suzuki, Satoshi Chiba, Toshitaka Kajino, Hidekazu Yokomakura, Keiichi
Kimura, Akira Takamura, Dieter H. Hartmann. "Neutrino-Nucleus Reaction Cross Sections for Light
Element Synthesis in Supernova Explosions", The Astrophysical journal, Vol. 686, No. 1, pp. 448–
466, Oct 2008.

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107) N. T. Okumuşoğlu, F. Korkmaz Gorur, J. Birchall, E. Sh. Soukhovitskii, R. Capote, J. M. Quesada,
S. Chiba. "Angular distributions of protons scattered by 40Ar nuclei with excitation of the 2 +(1.46 MeV) and 3− (3.68 MeV) collective levels for incident energies of 25.1, 32.5, and 40.7 MeV",
Physical Review C - Nuclear Physics, Vol. 75, 034616, Mar 2007.
108) S. Oryu, S. Nishinohara, N. Shiiki, S. Chiba. "Coulomb phase shift calculation in momentum space",
Physical Review C - Nuclear Physics, Vol. 75, 021001(R), Feb 2007.
109) L. Bonneau, T. Kawano, T. Watanabe, S. Chiba. "Nucleon direct-semidirect radiative capture with
Skyrme-Hartree-Fock-BCS bound states", Physical Review C - Nuclear Physics, Vol. 75, 054618,
May 2007.
110) Satoshi Kunieda, Satoshi Chiba, Keiichi Shibata, Akira Ichihara, Efrem Sh. SukhovitskĨ. "Coupledchannels Optical Model Analyses of Nucleon-induced Reactions for Medium and Heavy Nuclei inthe Energy Region from 1 keV to 200 MeV", Journal of Nuclear Science and Technology, Vol. 44,
6, pp. 838-852, 2007.
111) Toshiki Maruyama, Satoshi Chiba, Hans-Josef Schulze, Toshitaka Tatsumi. "Hadron-quark mixed
phase in hyperon stars", Physical Review D - Particles, Fields, Gravitation and Cosmology, Vol. 76,
123015, Dec 2007.
112) S. Nishinohara, S. Chiba, S. Oryu. "The Coulomb scattering in momentum space for few -bodysystems", Nuclear Physics A, Vol. 790, 1-4, pp. 277c-281c, Jun 2007.
113) K. Sumiyoshi, S. Yamada, H. Suzuki, S. Chiba. "Neutrino Signals from the Formation of a Black
Hole: A Probe of the Equation of State of Dense Matter", Physical Review Letters, Vol. 97, 091101,
Aug 2006.
114) Yuka Akimura, Toshiki Maruyama, Naotaka Yoshinaga, Satoshi Chiba. "Properties of Hadron and
Quark Matter Studied with Molecular Dynamics", Acta Physica Hungarica Series A, Heavy Ion
Physics, Vol. 27, pp. 355–358, Feb 2006.
115) Toshio Suzuki, Satoshi Chiba, Takashi Yoshida, Toshitaka Kajino, Takaharu Otsuka. "Neutrino nucleus reactions based on new shell model Hamiltonians", Physical Review C - Nuclear Physics,
Vol. 74, 034307, Sep 2006.
116) Satoshi Chiba, Mamoru Baba, Hiroshi Nakashima, Masahiro Ono, Naohiro Yabuta, Shigeru Yukinori,
Naohiro Hirakawa. "Interaction of fast neutrons with 6,7Li", Radiation Effects & Defects in Solids,
Vol. 92, 1-4, pp. 227-230, Aug 2006.
117) Toshiki Maruyama, Toshitaka Tatsumi, Dmitri N. Voskresensky, Tomonori Tanigawa, Tomoki Endo,
Satoshi Chiba. "Finite size effects on kaonic pasta structures", Physical Review C - Nuclear Physics,
Vol. 73, 035802, Mar 2006.
118) T. Hayakawa, S. Miyamoto, Y. Hayashi, K. Kawase, K. Horikawa, S. Chiba, K. Nakanishi, H.
Hashimoto, T. Ohta, M. Kando, T. Mochizuki, T. Kajino, M. Fujiwara. "Half-life of 184Re populatedby the (γ,n) reaction from laser compton scattering γ rays at the electron storage ring New
SUBARU", Physical Review C - Nuclear Physics, Vol. 74, 065802, Dec 2006.
119) Tomoyuki Maruyama, Satoshi Chiba. "Nuclear electromagnetic current in the relativistic approachwith the momentum-dependent self-energies", Physical Review C - Nuclear Physics, Vol. 74, 1,
014315, Jul 2006.
120) Toshiki Maruyama, Toshitaka Tatsumi, Tomoki Endo, Satoshi Chiba. "Pasta structures in compact
stars", Recent Research Developments in Physics, Vol. 7, pp. 1-57, 2006.
121) Toshihiko Kawano, Satoshi Chiba, Hiroyuki Koura. "Phenomenological Nuclear Level Densities- 25 25

JAEA-Conf 2023-001

Using the KTUY05 Nuclear Mass Formula for Applications Off-Stability", Journal of Nuclear
Science and Technology, Vol. 43, 1, pp. 1-8, 2006.
122) Tomoki Endo, Toshiki Maruyama, Satoshi Chiba, Toshitaka Tatsumi. "Charge Screening Effect inthe Hadron-Quark Mixed Phase", Progress of Theoretical Physics, Vol. 115, 2, pp. 337–353, Feb
2006.
123) T. Hayakawa, T. Shizuma, T. Kajino, S. Chiba, N. Shinohara, T. Nakagawa, T. Arima. "New s Process Path and Its Implications for a 187Re-187Os Nucleo-Cosmochronometer", The Astrophysicaljournal, Vol. 628, No. 1, pp. 533-540, Jul 2005.
124) T.Nakagawa, S.Chiba, T.Hayakawa, T.Kajino, Satoshi Chiba. "Maxwellian-averaged neutroninduced reaction cross sections and astrophysical reaction rates for kT = 1 keV to 1 MeV calculated
from microscopic neutron cross section library JENDL-3.3", Atomic Data and Nuclear Data Tables,
Vol. 91, 2, pp. 77-186, Nov 2005.
125) R. Capote, E. Sh. Soukhovitskii, J. M. Quesada, S. Chiba. "Is a global coupled-channel dispersive
optical model potential for actinides feasible?", Physical Review C - Nuclear Physics, Vol. 72,
064610, Dec 2005.
126) Y. Akimura, T. Maruyama, N. Yoshinaga, S. Chiba. "Molecular dynamics simulation for the baryon quark phase transition at finite baryon density", The European Physical Journal A - Hadrons andNuclei, Vol. 25, pp. 405-411, Sep 2005.
127) E. Sh. Soukhovitskii, R. Capote, J. M. Quesada, S. Chiba. "Dispersive coupled -channel analysis of
nucleon scattering from 232Th up to 200 MeV", Physical Review C - Nuclear Physics, Vol. 72,
024604, Aug 2005.
128) K. Sumiyoshi, S. Yamada, H. Suzuki, H. Shen, S. Chiba, H. Toki. "Postbounce Evolution of Core Collapse Supernovae: Long-Term Effects of the Equation of State", The Astrophysical Journal, Vol.
629, No. 2, 922-932, Aug 2005.
129) Tomonori Tanigawa, Masayuki Matsuzaki, Satoshi Chiba. "1S0 proton superfluidity in neutron star
matter: Impact of bulk properties", Physical Review C - Nuclear Physics, Vol. 70, 065801, Dec 2004.
130) Tomoyuki Maruyama, Satoshi Chiba. "In-Medium Effects in Eta Photo-Production through the S11
Resonance in the Relativistic Approach", Progress of Theoretical Physics, Vol. 111, 2, pp. 229 –243,
Feb 2004.
131) Hiroki Takemoto, Masahiro Fukushima, Satoshi Chiba, Hisashi Horiuchi, Yoshinori Akaishi, Akihiro
Tohsaki. "Clustering phenomena in nuclear matter below the saturation density", Physical Review C- Nuclear Physics, Vol. 69, 035802, Mar 2004.
132) Efrem Sh Soukhovitskii, Satoshi Chiba, Jeong-Yeon Lee, Osamu Iwamoto, Tokio Fukahori. "Global
coupled-channel optical potential for nucleon-actinide interaction from 1 keV to 200 MeV", Journalof Physics G: Nuclear and Particle Physics, Vol. 30, 7, 905–920, May 2004.
133) T. Matsumoto, E. Hiyama, K. Ogata, Y. Iseri, M. Kamimura, S. Chiba, M. Yahiro. "Continuum discretized coupled-channels method for four-body nuclear breakup in 6He + 12C scattering",
Physical Review C - Nuclear Physics, Vol. 70, 061601(R), Dec 2004.
134) Efrem Sh. SUKHOVITSKIĨ, Satoshi CHIBA, Jeong-Yeon LEE, Byung-taik KIM, Seung-Woo
HONG. "Analysis of Nucleon Scattering Data of 52Cr with a Coupling Scheme Built with the Softrotator Model", Journal of Nuclear Science and Technology, Vol. 40, 2, pp. 69-76, Feb 2003.
135) Weili Sun, Yukinobu Watanabe, Efrem Sh. SukhovitskiĨ, Osamu Iwamoto, Satoshi Chiba. "CoupledChannels Analysis of Nucleon Interaction Data of 28,30Si up to 200 MeV Based on the Soft Rotator- 26 26

JAEA-Conf 2023-001

Model", Journal of Nuclear Science and Technology, Vol. 40, 9, 635-643, Sep 2003.
136) Tomonori Tanigawa, Masayuki Matsuzaki, Satoshi Chiba. "Possibility of Λ Λ pairing and its
dependence on background density in relativistic Hartree-Bogoliubov model", Physical Review C Nuclear Physics, Vol. 68, 015801, Jul 2003.
137) Yuichi Hirata, Akira Ohnishi, Yasushi Nara, Toshihiko Kido, Toshiki Maruyama, Naohiko Otuka,
Koji Niita, Hiroshi Takada, Satoshi Chiba. "Sideward peak of intermediate mass fragments in highenergy proton induced reactions", Nucl. Phys. Vol. 707, 1-2, 193-212, Aug 2002.
138) Efrem Sh. Sukhovitskiĩ, Satoshi Chiba, Jeong-Yeon Lee, Young-Ouk Lee, Jonghwa Chang, Toshiki
Maruyama, Osamu Iwamoto. "Nuclear Level Structure, B(E2) Gamma-transitions and Nucleon
Interaction Data for 56Fe by a Unified Soft-rotator Model and Coupled-Channels Framework",
Journal of Nuclear Science and Technology, Vol. 39, 8, pp. 816-826, Aug 2002.
139) Tokio Fukahori, Yukinobu Watanabe, Nobuaki Yoshizawa, Fujio Maekawa, Shin-ichiro Meigo,
Chikara Konno, Naoki Yamano, Alexander Yu. Konobeyev, Satoshi Chiba. "JENDL High Energy
File", Journal of Nuclear Science and Technology, Vol. 39, No. sup2, pp. 25-30, Aug 2002.
140) Osamu Iwamoto, Jian Rong, Tokio Fukahori, Satoshi Chiba. "Calculation of Fission Reaction in the
Framework of QMD+SDM", Journal of Nuclear Science and Technology, Vol. 39, sup2, 128-131,
Aug 2002.
141) Toshiki Maruyama, Aldo Bonasera, Massimo Papa, Satoshi Chiba. "Formation and decay of superheavy systems", The European Physical Journal A - Hadrons and Nuclei, Vol. 14, 191–197, Jun 2002.
142) Toshiki Maruyama, Aldo Bonasera, Massimo Papa, Satoshi Chiba. "Lifetime of Heavy Composite
Systems Formed by Fusion between Heavy Nuclei", Journal of Nuclear and Radiochemical Sciences,Vol. 3, 1, 77-80, Jul 2002.
143) Masayoshi Kawai, Takashi Watanabe, Atsushi Zukeran, Hiroyuki Matsunobu, Satoshi Chiba, Tsuneo
Nakagawa, Yutaka Nakajima, Teruo Sugi, Klaus Dietze. "Interpretation of Integral Test Results of
FP Cross Sections in JENDL-3.2 by Analyzing the STEK Experiments", Journal of Nuclear Scienceand Technology, Vol. 39, sup2, 982-985, Aug 2002.
144) Keiichi Shibata, Toshihiko Kawano, Tsuneo Nakagawa, Osamu Iwamoto, Jun-ichi Katakura, Tokio
Fukahori, Satoshi Chiba, Akira Hasegawa, Toru Murata, Hiroyuki Matsunobu, Takaaki Ohsawa,
Yutaka Nakajima, Tadashi Yoshida, Atsushi Zukeran, Masayoshi Kawai, Mamoru Baba, Makoto
Ishikawa, Tetsuo Asami, Takashi Watanabe, Yukinobu Watanabe, Masayuki Igashira, Nobuhiro
Yamamuro, Hideo Kitazawa, Naoki Yamano, Hideki Takano. "Japanese Evaluated Nuclear Data
Library Version 3 Revision-3: JENDL-3.3", Journal of Nuclear Science and Technology, Vol. 39, 11,
pp. 1125-1136, Nov 2002.
145) Masahide Harada, Yukinobu Watanabe, Yasuhiro Tanaka, Yasuaki Matsuoka, Kazuo Shin, Shin ichiro Meigo, Hiroshi Nakashima, Hiroshi Takada, Toshinobu Sasa, Osamu Iwamoto, Tokio
Fukahori, Satoshi Chiba, Susumu Tanaka. "Light Charged-Particle Production in Proton-Induced
Reactions on 12C, 27Al, 58Ni, 90Zr, 197Au, and 209Bi at 42 and 68 MeV", Journal of Nuclear Scienceand Technology, Vol. 39, sup2, pp. 393-396, Aug 2002.
146) Masahiro Fukushima, Hideo Suganuma, Satoshi Chiba. "Instanton and Monopole in External
Chromomagnetic Fields", Progress of Theoretical Physics, Vol. 107, 6, pp. 1147–1161, Jun 2002.
147) Satoshi Chiba, Tokio Fukahori, Keiichi Shibata, Baosheng Yu, Kazuaki Kosako, Nobuhiro
Yamamuro. "JENDL Fusion File 99", Journal of Nuclear Science and Technology, Vol. 39, 2, Feb
2002.

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148) Keiichi Shibata, Akira Hasegawa, Osamu Iwamoto, Satoshi Chiba, Masayoshi Sugimoto, Naoteru
Odano, Toshihiko Kawano, Yutaka Nakajima, Toru Murata, Hiroyuki Matsunobu, Youl Soo Oh,
Kenji Yokoyama, Kazuteru Sugino, Makoto Ishikawa, Kazuaki Kosako, Naoki Yamano, Yukinori
Kanda. "JENDL-3.2 Covariance File", Journal of Nuclear Science and Technology, Vol. 39, sup2,
pp. 40-43, Aug 2002.
149) Efrem Sh. Soukhovitskiĩ, Satoshi Chiba. "Analyses of Nucleon Interaction with 238U up to 150 MeV
Incident Energies Using Coupled-Channels Approach with a Saturated Coupling Scheme Based on
Soft-Rotator Nuclear Model Hamiltonian", Journal of Nuclear Science and Technology, Vol. 39, sup2,
pp. 144-147, Aug 2002.
150) Efrem Sh. Soukhovitskiĩ, Satoshi Chiba. "Soft-Rotator Model and Coupled-Channels Approach for
Consistent Description of the Nuclear Collective Levels and Their Excitation by Nucleons", Journalof Nuclear Science and Technology, Vol. 39, sup2, 697-702, Aug 2002.
151) Weili Sun, Yukinobu Watanabe, Efrem Sh. Sukhovitskiĩ, Osamu Iwamoto, Satoshi Chiba.
"Evaluation of Cross Sections for Neutrons and Protons up to 200 MeV on Silicon Isotopes", Journalof Nuclear Science and Technology, Vol. 39, sup2, Aug 2002.
152) Toshiki Maruyama, Aldo Bonasera, Satoshi Chiba. "Nuclear fragmentation by tunneling", PhysicalReview C, Vol. 63, 057601, Apr 2001.
153) Shinpei Chikazumi, Toshiki Maruyama, Satoshi Chiba, Koji Niita, Akira Iwamoto. "Quantum
molecular dynamics simulation of expanding nuclear matter and nuclear multifragmentation",
Physical Review C, Vol. 63, 024602, Jan 2001.
154) Masayoshi Kawai, Tsuneo Nakagawa, Takashi Watanabe, Yutaka Nakajima, Atsushi Zukeran,Hiroyuki Matsunobu, Teruo Sugi, Satoshi Chiba. "Re-evaluation of Nuclear Data of Fission ProductNuclides for JENDL-3.2", Journal of Nuclear Science and Technology, Vol. 38, 4, 261-269, Apr 2001.
155) V. N. Kondratyev, Toshiki Maruyama, Satoshi Chiba. "Magnetic Field Effect on Masses of Atomic
Nuclei", The Astrophysical Journal, Vol. 546, No. 2, pp. 1137-1148, Jan 2001.
156) T. Maruyama, T. Hatsuda, S. Chiba. "Color molecular dynamics simulation of nuclei and dense
matter", Nuclear Physics A, Vol. 681, 1-4, 72-75, Jan 2001.
157) J.Y. Lee, E.S. Sukhovitski, Y.O. Lee, J. Chang, S. Chiba, O. Iwamoto. "Analyses of the Nuclear
Level Structure and Nucleon Interaction Data for 56Fe Based on the Soft-rotator Model", Journal of
Korean Physics Society, Vol. 38, 2, Feb 2001.
158) Efrem Sh. SukhovitskiĨ, Osamu Iwamoto, Satoshi Chiba, Tokio Fukahori. "Nucleon Optical
Potential of 238U up to 150 MeV", Journal of Nuclear Science and Technology, Vol. 37, No. 2, 120127, Feb 2000.
159) Masahide Harada, Yukinobu Watanabe, Akihisa Yamamoto, Yasuhiro Tanaka, Sun Weili, Kazuo Shin,
Shin-ichiro Meigo, Osamu Iwamoto, Hiroshi Nakashima, Hiroshi Takada, Satoshi Chiba, Tokio
Fukahori, Toshinobu Sasa, Susumu Tanaka. "Measurement of Double Differential Cross Sections ofSecondary Charged-Particles Produced by Proton-Induced Reactions at Several Tens of MeV",
Journal of Nuclear Science and Technology, Vol. 37, sup1, 687-691, Mar 2000.
160) Tokio Fukahori, Norio Kishida, Satoshi Chiba, Toru Murata, Tetsuo Asami, Kazuki Hida, Koichi
Maki. "Status of JENDL Photonuclear Data File and Intercomparison with Other Libraries", Journalof Nuclear Science and Technology, Vol. 37, sup1, pp. 728-732, Mar 2000.
161) Efrem Sh. Sukhovitskiĩ, Young-Ouk Lee, Jonghwa Chang, Satoshi Chiba, Osamu Iwamoto.
"Nucleon interaction with Ni-58 up to 150-MeV studied in the coupled channels approach based on- 28 28

JAEA-Conf 2023-001

the soft rotator nuclear structure model", physical review c, Vol. 62, 4, Sep 2000.
162) Satoshi Chiba, Osamu Iwamoto, Efrem Sh. Sukhovitskii, Yukinobu Watanabe, Tokio Fukahori.
"Coupled-channels optical potential for interaction of nucleons with 12C up to 150 MeV in the softrotator model", Journal of Nuclear Science and Technology, Vol. 37, 6, 498-508, Jun 2000.
163) Tomoyuki Maruyama, Satoshi Chiba. "Isoscalar Giant Quadrupole Resonance State in the
Relativistic Approach with the Momentum-Dependent Self-Energies", Physical Review C - Nuclear
Physics, Vol. 61, 037301, Feb 2000.
164) G. Mao, S. Chiba, W. Greiner, K. Oyamatsu. "Vacuum Discharge as a Possible Source of Gamma ray Bursts", International journal of modern physics E, Vol. 09, No. 02, pp. 185 -192, Apr 2000.
165) V. N. Kondratyev, T. Maruyama, S. Chiba. "Shell Structure of Nuclei in Strong Magnetic Fields in
Neutron Star Crusts", Physical Review Letters, Vol. 84, 1086, Feb 2000.
166) Toshihiko Kido, Toshiki Maruyama, Koji Niita, Satoshi Chiba. "MD simulation study for nuclear
matter", Nuclear Physics A, Vol. 663-664, 31, pp. 877c-880c, Jan 2000.
167) Kiminori Iga, Kenji Ishibashi, Nobuhiro Shigyo, Keisuke Maehata, Naruhiro Matsufuji, Tatsushi
Nakamoto, Masaharu Numajiri, Shin-ichirou Meigo, Hiroshi Takada, Satoshi CHIBA.
"Measurement of Gamma-Ray Production Double-Differential Cross Sections for 1.5 GeVπ+ Meson
Incidence on Iron", Journal of Nuclear Science and Technology, Vol. 37, 3, 211-214, Mar 2000.
168) Tomoyuki Maruyama, Satoshi Chiba. "Equation of state of neutron-star matter and the isovector
nucleon optical model potential", Journal of Physics G: Nuclear and Particle Physics, Vol. 25, 12,2361–2369, Dec 1999.
169) Toshiki Maruyama, Koji Niita, Kazuhiro Oyamatsu, Tomoyuki Maruyama, Satoshi Chiba, Akira
Iwamoto. "Nuclear matter structure studied with quantum molecular dynamics", Nuclear Physics A,
Vol. 654, 1, pp. 908c-911c, Jul 1999.
170) Efrem Sh. Sukhovitskiĩ, Satoshi Chiba, Osamu Iwamoto. "Coupled-channels optical model
calculations with account of nuclear volume conservation", Nuclear Physics A, Vol. 646, 1, pp. 19 28, Feb 1999.
171) Shin-ichiro MEIGO, Satoshi CHIBA, Kazuo SHIN. "Analysis of Neutron Spectra from Thick
Targets Bombarded with 710-MeV Alpha Particles by Quantum Molecular Dynamics plus Statistical
Decay Model", Journal of Nuclear Science and Technology, Vol. 36, 3, pp. 250-255, Mar 1999.
172) M. B. Chadwick, F. S. Dietrich, A. K. Kerman, A. J. Koning, S. M. Grimes, M. Kawai, W. G. Love,
M. Herman, F. Petrovich, G. Walker, Y. Watanabe, H. Wolter, M. Avrigeanu, E. Běták, S. Chiba, J.
P. Delaroche, E. Gadioli, S. Hilaire, M. S. Hussein, T. Kawano, R. Lindsay, A. Marcinkowski, B.
Mariański, M. Mustafa, E. Ramström, G. Reffo, W. A. Richter, M. A. Ross, S. Yoshida. "Openproblems in quantum-mechanical approaches to multistep direct nuclear reactions", Acta Physica
Slovaca, Vol. 49, 3, pp. 365-379, Jun 1999.
173) Y. Nara, N. Otuka, A. Ohnishi, K. Niita, S. Chiba. "Relativistic nuclear collisions at 10A GeV
energies from p+Be to Au+Au with the hadronic cascade model", Physical Review C, Vol. 61, 2,
Dec 1999.
174) M.B. Chadwick, P.G. Young, S. Chiba, S.C. Frankle, G.M. Hale, G. Hughes, A.J. Koning, R.C. Little,
R.E. MacFarlane, R.E. Prael, L.S. Waters. "Cross Section Evaluations to 150 MeV for AcceleratorDriven Systems and Implementation in MCNPX", Nuclear Science and Engineering, Vol. 131, 3,
293-328, Mar 1999.
175) Masahide Harada, Yukinobu Watanabe, Akihisa Yamamoto, Satoshi Yoshioka, Kazumichi Sato,- 29 29

JAEA-Conf 2023-001

Toshiyuki Nakashima, Hidenobu Ijiri, Hiroki Yoshida, Yusuke Uozumi, Norihiko Koori, Shin-ichiro
Meigo, Osamu Iwamoto, Tokio Fukahori, Satoshi Chiba. "The 12C(p,p'3α) Breakup Reaction
Induced by 14, 18 and 26 MeV Proton", Journal of Nuclear Science and Technology, Vol. 36, 4, pp.
313-325, Apr 1999.
176) S. Meigo, H. Takada, S. Chiba, T. Nakamoto, K. Ishibashi, N. Matsufuji, K. Maehata, N. Shigyo, Y.
Watanabe, M. Numajiri. "Measurement of Neutron Spectra Produced from a Thick Lead Target
Bombarded with 0.5- and 1.5-GeV Protons", Nuclear Instruments and Methods in Physics Research
Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 431, 3, pp. 521 530, Jul 1999.
177) S. Chiba, K. Togasaki, M. Ibaraki, M. Baba, S. Matsuyama, N. Hirakawa, K. Shibata, O. Iwamoto,A. J. Koning, G. M. Hale, M. B. Chadwick. "Measurement and theoretical analysis of neutron elastic
scattering and inelastic reactions leading to a three-body final state for 6Li at 10 to 20 MeV", PhysicalReview C - Nuclear Physics, Vol. 58, No. 4, 2205-2216, Erratum Phys. Rev. C 59, 558 (1999), Oct
1998.
178) A B Smith, P T Guenther, J F Whalen, S Chiba. "Fast-neutron total and scattering cross sections of
58Ni and nuclear models", Journal of physics G : nuclear and particle physics, Vol. 18, Number 4,629, Jan 1999.
179) Young-Ouk Lee, Jonghwa Chang, Tokio Fukahori, Satoshi Chiba. "Evaluation of Neutron- andProton-induced Nuclear Data on 27Al up to 2 GeV", Journal of Nuclear Science and Technology, Vol.
36, 12, pp. 1125-1134, Dec 1999.
180) Mark B. Chadwick, Phillip G. Young, Satoshi Chiba. "Photonuclear angular distribution systematics
in the quasideuteron regime", Journal of Nuclear Science and Technology, Vol. 32, 11, 1154 -1158,
Nov 1995.
181) Toshiki Maruyama, Koji Niita, Kazuhiro Oyamatsu, Tomoyuki Maruyama, Satoshi Chiba, Akira
Iwamoto. "Quantum molecular dynamics approach to the nuclear matter below the saturation
density", Physical Review C - Nuclear Physics, Vol. 57, 655, Feb 1998.
182) Kiminori Iga, Kenji Ishibashi, Nobuhiro Shigyo, Naruhiro Matsufuji, Tatsushi Nakamoto, Keisuke
Maehata, Masaharu Numajiri, Shin-ichirou Meigo, Hiroshi Takada, Satoshi Chiba, Takashi
Nakamura, Yukinobu Watanabe. "Measurement of Gamma-Ray Production Double-Differential
Cross Sections for the Spallation Reaction Induced by 0.8, 1.5 and 3.0 GeV Protons", Journal of
Nuclear Science and Technology, Vol. 35, No. 5, pp. 329-334, May 1998.
183) Efrem Sh.Sukhovitskiĩ, Satoshi Chiba, Osamu Iwamoto, Yurij V.Porodzinskiĩ. "Nucleon interaction
with 12C studied by the soft-rotator model and a limit on the charge-symmetry breaking in the nuclear
mean field", Nuclear Physics A, Vol. 640, 2, 147-162, Sep 1998.
184) H. Vonach, A. Pavlik, A. Wallner, M. Drosg, R.C. Haight, D.M. Drake, S. Chiba. "Spallation
reactions in 27Al and 56Fe induced by 800 MeV protons", Physical Review C - Nuclear Physics, Vol.
55, No. 5, 2458-2467, May 1997.
185) Satoshi Chiba, Osamu Iwamoto, Yoshimaro Yamanouti, Masayoshi Sugimoto, Motoharu Mizumoto,Kazuo Hasegawa, Efrem Sh. Sukhovitskiĩ, Yurij V.Porodzinskiĩ, Yukinobu Watanabe. "Consistentdescription of collective level structure and neutron interaction data for 12C in the framework of thesoft-rotator model", Nuclear Physics A, Vol. 624, 3, 305-327, Oct 1997.
186) Masahide Harada, Yukinobu Watanabe, Satoshi Chiba, Tokio Fukahori. "Evaluation of Neutron
Cross Sections of Carbon-12 for Energies up to 80MeV", Journal of Nuclear Science and Technology,- 30 30

JAEA-Conf 2023-001

Vol. 34, 2, pp. 116-127, Feb 1997.
187) Keiichi SHIBATA, Tokio FUKAHORI, Nobuhiro YAMAMURO, Keiichi SHIBATA, Tokio
FUKAHORI, Satoshi CHIBA, Nobuhiro YAMAMURO. "Evaluation of Neutron Nuclear Data for
Mercury", Journal of Nuclear Science and Technology, Vol. 34, No. 12, Dec 1997.
188) Satoshi Chiba, Tokio Fukahori, Keiichi Shibata, Baosheng Yu, Kazuaki Kosako. "Status andevaluation methods of JENDL Fusion File and JENDL PKA/KERMA File", Fusion Engineering and
Design, Vol. 37, 1, pp. 175-183, Aug 1997.
189) Tatsushi Nakamoto, Kenji Ishibashi, Naruhiro Matsufuji, Nobuhiro Shigyo, Keisuke Maehata,
Hidehiko Arima, Shin-ichirou Meigo, Hiroshi Takada, Satoshi Chiba, Masaharu Numajiri.
"Experimental Neutron-Production Double-Differential Cross Section for the Nuclear Reaction by
1.5-GeV π+ Mesons Incident on Iron", Journal of Nuclear Science and Technology, Vol. 34, 8, 860 862, Aug 1997.
190) Osamu Iwamoto, Satoshi Chiba, Ryousaku Kuwata. "Soft-rotator Model Analysis of Collective Band
Structures of Even-even Actinide Nuclei", Journal of Nuclear Science and Technology, Vol. 34, No.
5, May 1997.
191) Kenji Ishibashi, Hiroshi Takada, Tatsushi Nakamoto, Nobuhiro Shigyo, Keisuke Maehata, Naruhiro
Matsufuji, Shin-ichiro Meigo, Satoshi Chiba, Masaharu Numajiri, Yukinobu Watanabe, Takashi
Nakamura. "Measurement of Neutron-Production Double-Differential Cross Sections for Nuclear
Spallation Reaction Induced by 0.8, 1.5 and 3.0 GeV Protons", Journal of Nuclear Science andTechnology, Vol. 34, No. 6, pp. 529-537, Jun 1997.
192) Satoshi Chiba, Osamu Iwamoto, Tokio Fukahori, Koji Niita, Toshiki Maruyama, Tomoyuki
Maruyama, Akira Iwamoto. "Analysis of proton-induced fragment production cross sections by thequantum molecular dynamics plus statistical decay model", physical review c, Vol. 54, 285, Jul 1996.
193) Satoshi Chiba, Masahide Harada. "Applicability of Optical Model Potentials for IntermediateEnergy Nuclear Data Evaluations in the 1p-shell Mass Region", Journal of Nuclear Science andTechnology, Vol. 33, 4, 346-353, Apr 1996.
194) Satoshi Chiba, Mark B. Chadwick, Koji Niita, Toshiki Maruyama, Tomoyuki Maruyama, Akira
Iwamoto. "Nucleon-induced preequilibrium reactions in terms of the quantum molecular dynamics",
Physical Review C - Nuclear Physics, Vol. 53, 1824, Apr 1996.
195) Satoshi Chiba, Sin-ichi Morioka, Tokio Fukahori. "Evaluation of Neutron Cross Sections ofHydrogen from 20 MeV to 1 GeV", Journal of Nuclear Science and Technology, Vol. 33, 8, pp. 654662, Aug 1996.
196) A.B. Smith, S. Chiba. "Neutron scattering from elemental uranium and thorium", Annals of Nuclear
Energy, Vol. 23, 6, pp. 459-467, Apr 1996.
197) Satoshi Chiba, Koji Niita, Osamu Iwamoto. "Time scale of the preequilibrium process inintermediate-energy nucleon-induced reactions", Physical Review C - Nuclear Physics, Vol. 54, 3302,
Dec 1996.
198) Tomoyuki Maruyama, Koji Niita, Toshiki Maruyama, Satoshi Chiba, Yasuaki Nakahara, Akira
Iwamoto. "Relativistic Effects in Transverse Flow in the Molecular Dynamics Framework", Progressof Theoretical Physics, Vol. 96, 1, pp. 263–268, Jul 1996.
199) M. Baba, S. Matsuyama, M. Ishikawa, S. Chiba, T. Sakase, N. Hirakawa. "Correction of double differential neutron emission data for sample-dependent effects", Nuclear Instruments & Methods inPhysics Research. Section A, Vol. 366, 2-3, pp. 354-365, Dec 1995.

- 31 31JAEA-Conf 2023-001200) Tsuneo Nakagawa, Keiichi Shibata, Satoshi Chiba, Tokio Fukahori, Yutaka Nakajima, Yasuyuki
Kikuchi, Toshihiko Kawano, Yukinori Kanda, Takaaki Ohsawa, Hiroyuki Matsunobu, Masayoshi
Kawai, Atsushi Zukeran, Takashi Watanabe, Sin-iti Igarasi, Kazuaki Kosako, Tetsuo Asami.
"Japanese Evaluated Nuclear Data Library Version 3 Revision-2: JENDL-3.2", Journal of Nuclear
Science and Technology, Vol. 32, No. 12, 1259-1271, Dec 1995.
201) Watanabe Y, Aoto A, Kashimoto H, Chiba S, Fukahori T, Hasegawa K, Mizumoto M, Meigo S,
Sugimoto M, Yamanouti Y, Koori N, Chadwick MB, Hodgson PE. "Feshbach-Kerman-Kooninmodel analysis of preequilibrium (p,p') and (p,n) reactions at 12 to 26 MeV", Physical Review C Nuclear Physics, Vol. 51, 4, 1891-1907, Apr 1995.
202) M. B. Chadwick, S. Chiba, K. Niita, T. Maruyama, A. Iwamoto. "Quantum molecular dynamics andmultistep-direct analyses of multiple preequilibrium emission", Physical Review C - Nuclear Physics,
Vol. 52, 2800, Nov 1995.
203) Tatsushi NAKAMOTO, Kenji ISHIBASHI, Naruhiro MATSUFUJI, Nobuhiro SHIGYO, Keisuke
MAEHATA, Shin-ichirou MEIGO, Hiroshi TAKADA, Satoshi CHIBA, Masaharu NUMAJIRI,Takashi NAKAMURA, Yukinobu WATANABE. "Spallation Neutron Measurement by the Time -ofFlight Method with a Short Flight Path", Journal of Nuclear Science and Technology, Vol. 32, No. 9,
pp. 827-833, Sep 1995.
204) Koji Niita, Satoshi Chiba, Toshiki Maruyama, Tomoyuki Maruyama, Hiroshi Takada, Tokio
Fukahori, Yasuaki Nakahara, Akira Iwamoto. "Analysis of the (N,xN') reactions by quantum
molecular dynamics plus statistical decay model", Physical Review C - Nuclear Physics, Vol. 52,
2620, Nov 1995.
205) Mamoru Baba, Nobuo Ito, Isamu Matsuyama, Shigeo Matsuyama, Naohiro Hirakawa, Satoshi Chiba,
Tokio Fukahori, Motoharu Mizumoto, Kazuo Hasegawa, Shin-ichiro Meigo. "Differential αProduction Cross Sections of Iron and Nickel for 4.3 to 14.1 MeV Neutrons", Journal of Nuclear
Science and Technology, Vol. 31, pp. 745-747, Jul 1994.
206) Satoshi CHIBA, Donald L. SMITH. "Impacts of Data Transformations on Least-Squares Solutions
and Their Significance in Data Analysis and Evaluation", Journal of Nuclear Science and Technology,
Vol. 31, 8, 770-781, Aug 1993.
207) Baosheng Yu, Satoshi Chiba, Tokio Fukahori. "Examination of Various Kinds of Systematics ofDouble-Differential Particle Emission Cross Sections for Medium-Heavy Nuclei Important toFusion Neutronics", Journal of Nuclear Science and Technology, Vol. 29, 7, pp. 677-689, Jul 1992.
208) Chiba S, Guenther PT, Smith AB, Sugimoto M, Lawson RD. "Fast-neutron interaction withelemental zirconium, and the dispersive optical model", Physical Review C - Nuclear Physics, Vol.
45, Mar 1992.
209) S. Chiba, P. T. Guenther, R. D. Lawson, A. B. Smith. "Neutron scattering from elemental indium:
Optical model and bound-state potential", Physical Review C - Nuclear Physics, Vol. 42, 2487-2496,
Dec 1990.
210) S. Chiba, P. T. Guenther, A. B. Smith. "Some remarks on the neutron elastic—And inelastic—
Scattering cross sections of palladium", Annals of Nuclear Energy, Vol. 16, No. 12, pp. 637 -645,
Aug 1989.
211) Satoshi Chiba, Motoharu Mizumoto, Kazuo Hasegawa, Yoshimaro Yamanouti, Masayoshi Sugimoto,
Yukinobu Watanabe, Manfred Drosg. "The 1H(11B,n)11C reaction as a practical low backgroundmonoenergetic neutron source in the 10 MeV region", Nuclear Instruments and Methods in Physics- 32 32

JAEA-Conf 2023-001

Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 281, 3,
pp. 581-588, Sep 1989.
212) Satoshi Chiba, Yoshimaro Yamanouti, Masayoshi Sugimoto, Motoharu Mizumoto, Yutaka Furuta,
Mikio Hyakutake, Shin Iwasaki. "Fast neutron scattering cross sections of 118Sn at 14.9 and 18.0
MeV", Journal of Nuclear Science and Technology, Vol. 25, 6, pp. 511-519, Jun 1988.
213) Satoshi Chiba, Yoshimaro Yamanouti, Motoharu Mizumoto, Mikio Hyakutake, Shin Iwasaki.
"Measurements of Fast Neutron Scattering Cross Sections of Li-7 at 11.0 and 13.0 MeV", Journal of
Nuclear Science and Technology, Vol. 25, No. 2, pp. 210-214, Feb 1988.
214) Satoshi Chiba, Mamoru Baba, Hiroshi Nakashima, Masahiro Ono, Naohiro Yabuta, Shigeru Yukinori,
Naohiro Hirakawa. "Double-Differential Neutron Emission Cross Sections of 6Li and 7Li at Incident
Neutron Energies of 4.2, 5.4, 6.0 and 14.2 MeV", Journal of Nuclear Science and Technology, Vol.
22, No. 10, pp. 771-787, Oct 1985.

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4.

Conceptual Design Study of New Research Reactor
at the Monju Site

Kazufumi TSUJIMOTO
Japan Atomic Energy Agency
2-4, Shirakata, Tokai-mura, Naka-gun, Ibaraki-ken 319-1195, Japan
Email: tsujimoto.kazufumi@jaea.go.jp

In 2016, the Japanese government decided to decommission “MONJU” and to establish a newresearch reactor by utilizing “MONJU” site. In 2020, the Ministry of Education, Culture, Sports, Scienceand Technology (MEXT) concluded that a medium-power reactor (thermal power of less than 10 MW)
mainly for neutron beam applications would be most appropriate for a new research reactor using the“MONJU” site. The consortium consisted with Japan Atomic Energy Agency, Kyoto University, and the
University of Fukui was selected as the core organization for the conceptual design of the new research
reactor. The present paper describes the status of conceptual design study of new research reactor at
the Monju site that has been conducted mainly by JAEA.

1. Introduction
In December 2016, when the government policy to decommission “MONJU” was decided at the
Nuclear Energy Ministerial Meeting, it was decided to establish a new research reactor by utilizing the"MONJU" site in the future. In response, Ministry of Education, Culture, Sports, Science and Technology(MEXT) established a committee of external experts consisting of various stakeholders from FY 2017 toFY 2019 to conduct a survey on a new research reactor, and selected several candidate reactor types in
May 2020. Specifically, (1) Medium-power reactor (thermal power of less than 10 MW, mainly for
research using neutron beams and highly versatile), (2) Low-power reactor (thermal power of about 500
kW, mainly used for nuclear engineering experiments), (3) Zero-Power critical experiment facility(thermal power of about a few kW, mainly used for basic research and education) were selected as reactor
types that could be constructed by incorporating the latest technology based on existing reactors. Afterhearing to the opinions of Fukui Prefecture and Tsuruga City, and through discussions at the Working
Group on Nuclear Research and Development, Infrastructure, and Human Resources of MEXT, in
September 2020, the most appropriate reactor type was selected as a medium power reactor (<10 MW)
mainly for neutron beam applications, from two perspectives: to realize functions suitable as a core centerfor nuclear research and development and human resources development in western Japan and tocontribute to local development. Moreover, as a way to proceed with the study, it was recommended toestablish an organization consisting with research institutes and universities with knowledge, experience,- 34 34

JAEA-Conf 2023-001

and ability in the three aspects of "steady design, construction, and operation of the research reactor,""operation of the research reactor so that a wide range of related researchers can use it," and"establishment of cooperation with related local organizations".
In order to effectively implement the study on the conceptual design and operation of the newresearch reactor from the above recommendation, MEXT issued a public offering ("Study on theconceptual design and operation of the new research reactor at the Monju site") and selected theconsortium consisted with Japan Atomic Energy Agency (JAEA), Kyoto University, and the Universityof Fukui as the core organizations in November 2020. The roles of each organization are
JAEA : Design, construction, and operation of new research reactor,
Kyoto University : Operation of a wide range of utilization, andUniversity of Fukui : Building partnerships with local institutions.
The present paper describes the status of conceptual design study of new research reactor at the Monjusite that has been conducted mainly by JAEA.

2. Conceptual Design Study of Reactor Core
2.1. Design Targets
In the conceptual design study of the new research reactor, it is possible to refer to the knowledgeof existing research reactors such as JRR-3 of JAEA and KUR of Kyoto University, which haveknowledge and experience in construction and operation management. The goal of this project is tomaximize the performance as a medium-power reactor mainly for neutron beam applications. The basic
policies of this project are (1) increasing safety performance, (2) improving user convenience, (3)ensuring operation stability, (4) exploring economical design, and (5) securing future potential. Figure 1
shows the relationship between the basic policy and typical items that should be specifically consideredwhen conducting a conceptual design study.
（Basic policy）
Increase safety performance(Specification)
Simplify core submergence
Simplify decay heat removal

Improve user convenience

Neutron flux same as JRR-3

High neutron flux
Adjustability of neutron
spectrum

Ensure operation stability

Open pool-type

Enlarge operation cycle

Effective moderator
Cold neutron source

High burnup

Longer operation cycle

Explore economical design

Low cost of fuelOptimized core

Securing future potential

Minimize of spent fuel

Fuel with proven tech.

Fig.1 Relationship between the basic policy of the core concept study and specific study items
In order to concretize the core configuration of the new research reactor as a medium power reactor,
the maximum thermal neutron flux in the reflector and the available operation days were set as tentative
design targets to be achieved as follows.

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JAEA-Conf 2023-001

࣭Maximum thermal neutron flux㸸> 1014 n/cm2/s㸦JRR-3 : 1.0㹼2.01014 n/cm2/s㸧࣭Available operation days㸸> 400 days㸦JRR-3 : 370 days㸧
It is desirable to achieve as high thermal neutron flux as possible in the new research reactor whose
main purpose is to utilize neutron beams. In addition, since the number of days of sustainable operation
is directly related to the availability of the new research reactor, it is desirable to be able to maintain
operation for as long as possible without fuel replacement. These design targets were set with reference
to the performance of the JRR-3 (20 MW thermal power) currently in operation at JAEA. For the
maximum thermal neutron flux, the target was set to equivalent to that of the JRR-3 although the thermal
power of the new research reactor is half that of JRR-3. The operation days set here is the number of days
until the effective multiplication factor will fall below 1 in the burnup analysis, which is different fromthe actual available operation days.
2.2. Core Configuration
In the consideration of the core design, core configurations with various fuel element numbers andarrangements were assumed, and their respective neutron fluxes and burnup characteristics were analyzed.
The calculations were performed under the assumption using JRR-3 fuel element. Table 1 shows the main
parameters of the JRR-3 fuel element which is a typical MTR-type fuel element. Figure 2 shows theschematic drawing of the JRR-3 fuel element. The JRR-3 core consists of standard fuel elements andfollower-fueled control rods, but in this study, it was assumed that the core consists entirely of standard
fuel elements.
Table 1 Main parameters of JRR-3 fuel element
Size
Nuclear Fuel
235U enrichment
235U content
Uranium density
Fuel meat

64×64×880 mm
U3Si2
20 wt%
300 g
4.8 g/cm3
0.51 mm
49 mm
750 mmAl alloy
0.38 mm
1.27 mm
60 mm
770 mm16
2.40 mm (×15)

Thickness
Width
LengthCladding
Cladding thickness
Thickness
Fuel plate
Width
LengthNumber of coolant channel
Coolant channel thickness

For the core configuration, we analyzed the neutron flux and burnup characteristics for each of theassumed fuel numbers and fuel configuration pairs shown in Figure 3. In setting the core geometry, notonly the number of fuels is used as a parameter, but also the core outline is kept the same, as in x16, x17,
and Ce20, and the number of fuels constituting the core is adjusted so that only the effect of the numberof fuels can be considered. It is assumed that the coolant region of the fuel elements is filled with light- 36 36

JAEA-Conf 2023-001

water, and the outside of the core is surrounded by heavy water of sufficient thickness. The continuous
energy Monte Carlo codes MVP 1) and MVP-BURN were used for the calculations, and JENDL-4.02) wasused for the nuclear data.
0.051cm×6.2cm×75cm（20% enriched 235U）

Fuel plate
7.62cmFuelelement

Horizontal cross section
vies of fuel element

Fig.2 Standard JRR-3 fuel element

c12

c13

4x4 (16)5x5 (25)

Fuel element

Aluminum(Irradiation hole)

X16

ce20

x17

Fig.3 Fuel element arrangement analyzed in the core concept study
The thermal neutron flux in the heavy water tank outside the core and the change of effective
multiplication factor due to burnup for each core configuration are shown in Figures 4 and 5, respectively.
Although the maximum thermal neutron flux became smaller as the number of fuel elements increased
and the core became larger, the maximum thermal neutron flux for all core geometries was found to beabout 10 cm from the core edge, which is higher than the target of 10 14 n/cm2/s. On the other hand, as forthe burnup characteristics, it was also found that as the number of fuel elements increa ses and the core
becomes larger, the period when the effective multiplication factor falls below one increases, the number- 37 37

JAEA-Conf 2023-001

of days of operation becomes longer, the burnup rate of 235U increases, and the fuel can be used more
efficiently. Among the configured cores, 5x5 cores (25 fuel elements, 588 days of sustainable operation,
61% burnup) and ce20 cores (20 fuel elements, 416 days of sustainable operation, 55% burnup) met thetarget of 400 days of sustainable operation.
Based on the above results, it was decided that the Ce20 core is the reference configuration which

Effective eigenvalue (k-eff)

has potential address a wide variety of needs because irradiation utilization will be available at the centerand the four corners of the core, and it is relatively more flexible than the 5×5 core.

Burnup (days)

U-235 burnup (%)

Fig.4 Comparison of calculated thermal neutron flux in heavy water tanks

4x4

c13
c12
x16

ce20

5x5

x17

: Burnup days at keff=1.0

Burnup (days)
Fig.5 Change of effective multiplication factor (k eff) with burnup

3. Concluding remarks
In the conceptual design study of the reactor core, the maximum thermal neutron flux in the heavy
water reflector and the number of days of operation duration were set as the design goals to be achieved,
and a core configuration capable of achieving each goal was obtained. Based on these results, the fuelelements, control elements, and reflector will be concretized to determine the basic specifications to- 38 38

JAEA-Conf 2023-001

proceed with the detailed design.
On December 23, 2022, JAEA was selected by MEXT as the main entity to implement the newexperimental research reactor project at the "MONJU" site from the detailed design stage onward. We
will continue to work with Kyoto University and the University of Fukui to steadily proceed with the
project, while gathering a wide range of opinions from related organizations and gaining theunderstanding of the local community, following the schedule as shown in the Fig.6

FY2020 2022
FY2020～2022
Conceptual
Conceptual
designGeological survey

FY2022~
Detailed design I, II
Licensing and approvals from NRA

Construction
truction works
ks andInspections

Detailed design I: Application for licensing
Detailed design II: Licensing and Approvals plan for
construction works

FY2020Operation

Approvals from NRA

FY2021

FY2022

FY2023 ~Facility utilization
management etc.

'HWDLOHGGHVLJQ,Conceptual design

Geological survey

Fig.6 Tentative Schedule for construction and operation of the new research reactor at Monju site

References
1)

Nagaya, Y, Okumura, K. Sakurai, T. et al., MVP/GMVP version 3; General purpose Monte
Carlo codes for neutron and photon transport calculations based on continuous energy andmultigroup methods, Japan Atomic Energy Agency, JAEA-Data/Code 2016-018 (2017).

2)

Shibata K., Iwamoto O., Nakagawa T. et al., JENDL-4.0: A New Library for Nuclear Scienceand Engineering," J. Nucl. Sci. Technol.. 48(1), 1-30 (2011).

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JAEA-Conf 2023-001

5. Measurement of 100 MeV-range nuclear reaction
data using the fixed field alternating gradientaccelerator at Kyoto University
Hiroki IWAMOTO1
1†

Japan Atomic Energy Agency
E-mail: iwamoto.hiroki@jaea.go.jp

Abstract
For the research and development of accelerator-driven systems (ADSs) and fundamental
ADS reactor physics research using the Kyoto University Critical Assembly combined withthe fixed-field alternating gradient (FFAG) accelerator, we are conducting experiments on
100 MeV-range nuclear reaction data using the FFAG accelerator at Kyoto University. This
paper presents an overview of the experiments.

1

Introduction

Spent fuel from nuclear power plants is radioactive and toxic for a long period of time, even tensof thousands of years. From the viewpoint of effective utilization of energy resources, Japan’s
basic policy is to reprocess the spent fuel to recover plutonium (Pu) and uranium (U) andreuse them as fuel. The high-level radioactive liquid waste (HLW) produced in the reprocessing
process will be vitrified and disposed into a stable bedrock formation several hundred meters
underground. It is of social significance to reduce the toxicity of HLW as much as reasonably
achievable and to reduce the burden of geological disposal. As one of the solutions to thisproblem, Accelerator-Driven System (ADS) has attracted attention and is being researched anddeveloped around the world.
Figure 1 shows the concept of the ADS proposed by the Japan Atomic Energy Agency(JAEA). This system is a combined reactor system that combines a 1.5 GeV high-intensity
proton accelerator and a subcritical core to efficiently perform transmutation while keeping thecore subcritical. The core is loaded with nuclear fuel containing minor actinides (MA) suchas neptunium (Np) and americium (Am), which have particularly high radio-toxicity among
HLW, and is surrounded by a liquid lead-bismuth eutectic (LBE) alloy. The LBE is used as acoolant to extract the heat generated from the nuclear fuel during operation, and also serves as atarget or spallation neutron source to supply spallation neutrons generated by nuclear reactions(spallation reactions) using high-energy protons to the core.
Figure 2 shows the time behavior of the potential radiotoxicity of radioactive waste [1]. If
Pu and U are recovered from the waste and MA with high potential radiotoxicity are separated
and burned in ADS, the toxicity can be reduced to several hundred years, which is expected tomake a significant contribution to solving the problem of negative legacy.
In the research and development of ADS using spallation neutrons, it is important to improve
nuclear reaction models that describe spallation reactions. In particular, the yield of spallation
neutrons, their energy distribution (spectrum), and angular distribution obtained by the nuclear- 40 40

JAEA-Conf 2023-001

Figure 1: Concept of ADS proposed by JAEA.
reaction model calculation are essential information for evaluating the nuclear performance of the
ADS, such as transmutation efficiency and proton beam current. In addition, the beam window,
which forms the boundary between the proton injection region and the core region, is irradiatedby high-energy protons and produces gases such as helium and hydrogen inside the material.
Accurate prediction of gas production and irradiation damage in the beam window, which is
exposed to severe thermal conditions, is important to ensure its performance and integrity inthe design. In addition, it is necessary to accurately evaluate the induced radioactivity of thespallation target and constituent materials and the shielding performance of neutron shields, andnuclear reaction models that describe these fundamental processes play an extremely importantrole.
At Kyoto University, a series of experimental studies simulating ADS has been conductedusing the Kyoto University Critical Assembly (KUCA) coupled with the FFAG (Fixed Field
Alternating Gradient) accelerator; the nuclear reaction model is being verified in this framework[2]. On the other hand, in the actual ADS, which assumes deeper subcriticality than the subcritical regime that can be tested in KUCA, the contribution of spallation reactions to the neutronenergy spectrum increases, so that more accurate nuclear reaction model analysis is required fornuclear performance evaluation and demonstration experiments.
Due to the importance of nuclear reaction models in ADS nuclear design, measurementsof the double-differential cross section (DDX) of neutrons and charged particles and the neutron yield of neutrons emitted from a thick Pb target (i.e., thick target neutron yield, TTNY)
have been measured intensively by research institutes around the world, and the nuclear reaction models have been refined and benchmarked by the International Atomic Energy Agency(IAEA) [3]. However, despite these efforts, the reaction mechanisms of neutron-production DDX
and TTNY and high-energy fission in the tens to 100 MeV region have not yet been predictedwith satisfactory accuracy even by the latest nuclear reaction models. In this background, weare planning to measure neutron-production DDX and TTNY for ADS components (Fe, Pb,
and Bi), fission fragment distribution and fission neutron number in high-energy fission of Pb
and Bi using the FFAG accelerator, which can accelerate protons in the 100 MeV region. The
experimental data obtained from these measurements will be compared with the nuclear reaction
model (theoretical model) in order to improve the statistical accuracy of the nuclear reaction- 41 41

JAEA-Conf 2023-001

Figure 2: Reduction of potential radiotoxicity of spent fuel by ADS (partitioning and transmutation) technology, plotted based on Ref. [1].
model.

2

Experiment

The experiments were conducted in the experimental hall where the FFAG accelerator is installedin the Innovation Research Laboratory of the Institute for Integrated Radiation and Nuclear
Science, Kyoto University. A series of experiments on TTNY and DDX have been completed, andexperiments on high-energy fission of Pb and Bi are planned. Figure 3 shows the experimental
setup for the TTNY and DDX measurements. In each of these experiments, a disc-shaped target
is placed in a vacuum chamber on a different beamline, and a neutron detector is positioned
at a specific angle of 5–120 degrees from the proton beam injection axis, about 2–7 m awayfrom the target (Figure 4). After the target and neutron detector were set up, the target wasirradiated with a 107-MeV proton beam accelerated by the FFAG accelerator for 1–4 hours todetect neutrons and gamma rays emitted from the target during irradiation.
In the TTNY measurements, Fe (beam window component), Pb, and Bi (spallation target
component), which are the main components of ADS, were used as targets, and their thickness
was 30 mm so that they were longer than the range for 107-MeV protons (i.e. 16.1 mm, 15.9mm, and 18.5 mm for Fe, Pb, and Bi, respectively). The target thickness for DDX measurements
should be thin from a physical point of view, but for better statistics, 2-mm-thick Pb and 5-mmthick Bi were used to improve the accuracy. The diameter of the target was 48 mm to ensurethat the proton beam would enter the target with sufficient margin based on past beam profiles.
The beam repetition rate was set to the standard FFAG accelerator specification of 30 Hz.
The time width of the pulsed beam before the experiment was about 100 ns, but since a time
width of less than 10 ns is required to obtain high energy resolution for TTNY and DDX
measurements, the pulsed beam was shortened to ∼8 ns (1σ) by the bunch rotation method
and the kicker method [4]. The beam profile was checked by placing a fluorescent plate near thetarget and using a CCD camera to observe the scintillation from the proton beam irradiation.

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JAEA-Conf 2023-001

Figure 3: Experimental setup of the TTNY and DDX measurements.
This check was performed before each TTNY and DDX measurement at each measurement
angle.
In order to measure neutron energy spectra with high detection efficiency over a wide energy
range from several hundred keV to 107 MeV, we used a compact EJ-301 with a diameter of 8mm and a PMT (HAMAMATSU H3164-12) that can handle a wide luminous flux band. In the
TTNY measurement, a 16 mm thick copper block was placed in front of the neutron detector
to prevent charged particles such as scattered protons from entering the detector. In the DDX
measurement, on the other hand, a VETO detector consisting of a light-guided plastic scintillator
and PMT with a thickness of 2 mm and a length and width of 100 mm was placed in front of
the neutron detector to eliminate charged particle events detected by the neutron detector.
Data acquisition (DAQ) during the measurement was performed using a multichannel digitizer (Struck Innovative System, model No. SIS3316) with a field-programmable gate array(FPGA). The pulse-shape discrimination (PSD) method was used to discriminate between neutron and gamma-ray events detected by the neutron detectors, where two different gates (fast andslow gates) were set and the integral amount of scintillation at each gate width was recorded
as a digital signal. The time-of-flight (TOF) method was used to derive the TOF spectrumof neutrons based on the time information of neutron detection events obtained by removing
gamma-ray detection events by the PSD method. The contribution of room-scattering neutrons
was removed by the results of measurements using a shadow bar. Furthermore, the neutron
TOF spectra were converted to energy spectra based on relativistic kinematics by correcting fordetector detection efficiency, target-to-detector neutron attenuation, and other factors based on
analysis using the radiation behavior analysis code PHITS [5].
The energy spectra of TTNY and DDX for Fe, Pb, and Bi targets were obtained from- 43 43

JAEA-Conf 2023-001

this experiment. As an example, Figure 4 shows a comparison between the experimental dataof 107-MeV proton-induced TTNY for Pb and the nuclear reaction model analysis. The results of the analysis using the nuclear reaction models incorporated in PHITS (INCL4.6/GEM,
Bertini/GEM, JQMD/GEM, and JQMD/SMM/GEM [6, 7, 8, 9, 10]) and the evaluated nuclear
data library JENDL-4.0/HE [11] are described here. The energy distribution at high energies
is strongly forward, while at low energies, the distribution is isotropic and Maxwellian. Thisis because the mechanism of neutron emission from nuclei is very different between the twoprocesses in nuclear reactions, which are described by the intranuclear cascade model and theevaporation model included in nuclear reaction models, respectively. The TTNY and DDX dataobtained in this experiment cover a wide energy range from 700 keV to 107 MeV. Comparison
with the nuclear reaction models revealed that both models show a characteristic discrepancy
trend with respect to the TTNY measurements for Fe, Pb, and Bi (see Ref. [12] for details of
the TTNY measurements). The same trend was observed for DDX (see Ref. [13] for preliminary
results).

Figure 4: Comparison of energy spectra of 107-MeV proton induced TTNY for Pb. (Ref. [12]).

3

Summary and future work

Experiments on neutron production DDX and TTNY of ADS components and high energy
fission have been conducted and planned using the FFAG accelerator at Kyoto University. Sofar, measurements of TTNY and DDX have been completed, and we have succeeded in obtaining
data that will contribute to the advancement of nuclear reaction models. In the future, we plan
to conduct experiments on high-energy fission of Pb and Bi.

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JAEA-Conf 2023-001

References[1] K. Nishihara, “Data for estimating potential radioactivity of spent nuclear fuel”, JAEA-Data/
Code 2010-012 (2010).
[2] C. Pyeon et al., “Reaction rate analyses of accelerator-driven system experiments with 100 MeV
protons at Kyoto University Critical Assembly”, J. Nucl. Sci. and Technol., vol. 55, no. 2,
2018, pp.190–198, 2009. doi:10.1080/00223131.2017.1389314[3] D. Filges et al., Joint ICTP-IAEA Advanced Workshop on Model Codes for Spalla-tion
Reactions, Trieste, Italy 4–8 Feb. 2008. http://www-nds.iaea.org/reports-new/indc-reports/indcnds/indc-nds-0530.pdf[4] T. Uesugi et al., “Short pulsed beam extraction in KURNS FFAG”, Proc. the 18th Annual
Meeting of Particle Accelerator Society of Japan, QST-Takasaki Online, Japan, Aug. 9–12,
2021; http://www.pasj.jp/web_publish/pasj2021/proceedings/index.html[5] T. Sato et al., “Features of particle and heavy ion transport code system (PHITS) version 3.02.
J. Nucl. Sci. and Technol., vol. 55, no. 6, 2018, pp.684–689, 2018. doi:10.1080/
00223131.2017.1419890[6] A. Boudard et al., “New potentialities of the Liège intranuclear cascade model for reactions
induced by nucleonns and light charged particles”. Phys. Rev. C, vol. 87, p.014606, 2013.
doi:10.1103/PhysRevC.87.014606[7] S. Furihata, “Statistical analysis of light fragment production from medium energy protoninduced reactions”, Nucl. Instrum. Methods Phys. Res. B., vol. 171, pp.251–258, 2000.
doi:10.1016/S0168-583X(00)00332-3[8] H. Bertini, “Intranuclear-cascade calculation of the secondary nucleon spectra from nucleonnucleus interactions in the energy range 340 to 2900 MeV and comparisons with experiment”, Phys. Rev., vol. 188, p.1711, 1969. doi:10.1103/PhysRev.188.1711[9] K. Niita et al., “Analysis of the (N, xN ′) reactions by quantum molecular dynamics plus sta-tistical
decay model”, Phys. Rev. C, vol. 52, pp.2620–2635, 1995. doi:10.1103/PhysRevC. 52.2620[10] T. Ogawa et al., “Analysis of multi-fragmentation reactions induced by relativistic heavy ionsusing the statistical multi-fragmentation model”, Nucl. Instrum. Methods Phys. Res. A., vol.
723, pp.36–46, 2013. doi:10.1016/j.nima.2013.04.078[11] S. Kunieda et al., “Overview of JENDL-4.0/HE and benchmark calculations”. Proc. 2015
Symposium on Nuclear Data, Tokai, Nov 19–20; JAEA-Conf 2016-004, pp.41–46, 2016.
[12] H. Iwamoto et al., “Measurement of 107-MeV proton-induced double-diﬀerential thick target
neutron yields for Fe, Pb, and Bi using a ﬁxed ﬁeld alternating gradient accel-erator at Kyoto
University”, J. Nucl. Sci. and Technol., published online, 2022.
doi: 10.1080/00223131.2022.2115423[13] H. Iwamoto et al., “Measurement of double-diﬀerential neutron yields for iron, lead, and bismuth
induced by 107-MeV protons for research and development of accelerator driven systems”, Proc.
of 15th International Conference on Nuclear Data for Science and Tech-nology (ND2022), 21–29
July 2022, Gather.Town, 2022.

Acknowledgments
This work was supported by MEXT Innovative Nuclear Research and Development Program
Grant Number JPMXD0219214562. We would like to express our gratitude to Dr. Daisuke
Maki and Prof. Yuichi Oki of Kyoto University for their support.

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6. Measurement and evaluation of DD neutron field
Characteristics for OKTAVIAN

Hikaru MATSUNAGA1*, Ryotaro KAWAHATA1, Shingo TAMAKI1, Sachie KUSAKA1,
Fuminobu SATO1 and Isao MURATA1
Graduate school of Engineering, Osaka University

1

2-1 Yamadaoka, Suita-shi, Osaka-fu 565-0871, Japan*Email: matsunaga21@qr.see.eng.osaka-u.ac.jp

Abstract:
OKTAVIAN is a DT and DD neutron irradiation facility in Osaka University. However, DD neutron
source in OKTAVIAN has not been well characterized in terms of angular distribution of neutron intensity
and neutron energy distribution, though characterized neutron fields are essential for the applications such as
development and calibration of radiation detectors. Therefore, it is necessary to evaluate the DD neutron field
in OKTAVIAN.
In this study, we measured the angular distribution of DD neutron from 0° to 150° by 15° intervals, andmeasured the total neutron production rate of OKTAVIAN by foil activation method with indium.
Experimental results were compared with calculated results derived using SRIM, Drosg-2000 and MCNP5,
and we discussed about the comparison of the present result with past cross section measurement result, theaccuracy of the neutron source term and the validity of the simulation methods. As a result, no significant
difference was found less than 135° between experimental and simulation values and at 150°, the simulated
intensity was smaller than the experimental result. In conclusion, we confirmed the accuracy of the derived
neutron source term and the validity of the simulation method and, revealed the total neutron production rateby OKTAVIAN.

1.

Introduction
OKTAVIAN in Osaka University has been used as DT and DD neutron sources for nuclear fusion reactor

research since 1981 [1]. Especially the DT neutron source using T(d, n)4He reaction has a strong intensity of
3×1012 neutrons per second at maximum and has been primarily used for fusion neutronics studies such as
various benchmark experiments including tritium breeding ratio measurements, and in addition for otherapplications like boron neutron capture therapy (BNCT) and so on [2-3]. On the other hand, DD neutron
generated from D(d, n)3He reaction can be utilized for such as oil exploration, active neutron interrogation
for fissile materials, neutron imaging and so on [4-6]. However, the DD neutron field in OKTAVIAN has notbeen well characterized in terms of angular distribution of neutron intensity and neutron energy distribution.

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JAEA-Conf 2023-001

Therefore, it is necessary to evaluate the DD neutron field in OKTAVIAN.
In this study, we measure the angular distribution for DD neutron by activation method using indiumfoil, and measure the total neutron production rate by OKTAVIAN. We also characterize the neutron source
term for Monte Carlo neutron transport calculation code using SRIM and Drosg-2000, and neutron transport
simulation is carried out to calculate the expected angular distribution of neutron flux intensity in realexperiment by MCNP5. Finally, we compare the experimental results with the calculation results to confirm
whether the calculation results with the past nuclear data reproduce the present experiment.
2.

Experimental method

2.1 Measurement method
In this study, DD neutron irradiated by OKTAVIAN was measured by foil activation method using
indium foil. The irradiated DD neutron activated indium foils according to nuclear reaction described as Eq.
1,
115

𝐼𝐼𝐼𝐼 + n → 115𝐼𝐼𝐼𝐼∗ + n′

𝐼𝐼𝐼𝐼∗ → 115𝐼𝐼𝐼𝐼 + 𝛾𝛾 (336 𝑘𝑘𝑘𝑘𝑘𝑘).

115(Eq. 1)After that, radioactivity of indium foil can be derived by measuring the number of 336 keV 𝛾𝛾-rays

emitted from the activated indium by a germanium detector. The number of measured 𝛾𝛾 -rays count isexpressed in the following equation,𝑡𝑡𝐶𝐶𝛾𝛾,𝜃𝜃𝜄𝜄 = 𝑁𝑁0 ∫0 𝑖𝑖 ∫𝐸𝐸 𝜎𝜎(𝐸𝐸)𝜑𝜑(𝐸𝐸, 𝑡𝑡)𝜃𝜃𝑖𝑖 𝑑𝑑𝐸𝐸 ∙ 𝑘𝑘𝜆𝜆𝑡𝑡 𝑑𝑑𝑡𝑡 × 𝑘𝑘−𝜆𝜆(𝑡𝑡𝑖𝑖+𝑡𝑡𝑐𝑐 ) × (1 − 𝑘𝑘 −𝜆𝜆𝑡𝑡𝑚𝑚 ) × 𝐼𝐼𝛾𝛾 × 𝑓𝑓𝑛𝑛 × 𝑓𝑓𝑔𝑔 × 𝜀𝜀,

where 𝐶𝐶𝛾𝛾,𝜃𝜃𝜄𝜄 is measured count of 𝛾𝛾 rays emitted from indium foil placed at 𝜃𝜃𝜄𝜄 degrees, 𝑁𝑁0 is thenumber of 115𝐼𝐼𝐼𝐼 atoms in the foil, 𝜆𝜆 is decay constant of 115𝐼𝐼𝐼𝐼∗ , 𝑡𝑡𝑖𝑖 is irradiation time, 𝑡𝑡𝑐𝑐 is cooling time,
𝑡𝑡𝑚𝑚 is measurement time, 𝐼𝐼𝛾𝛾 is 𝛾𝛾 rays emission ratio, 𝑓𝑓𝐼𝐼 is self-shielding factor, 𝑓𝑓𝑔𝑔 is self-absorption factor,and 𝜀𝜀 is a detection efficiency of the germanium. We employed JENDL-5 [7] as a nuclear data library for
activation cross section 𝜎𝜎(𝐸𝐸) . 𝜑𝜑(𝐸𝐸, 𝑡𝑡)𝜃𝜃𝑖𝑖 is the time dependent neutron spectrum, described as𝜑𝜑(𝐸𝐸, 𝑡𝑡)𝜃𝜃𝑖𝑖 = φ𝜃𝜃𝑖𝑖 × 𝑃𝑃(𝐸𝐸)𝜃𝜃𝑖𝑖 × 𝑓𝑓(𝑡𝑡), where 𝑃𝑃(𝐸𝐸)𝜃𝜃𝑖𝑖 is neutron energy spectrum normalized as unity, 𝑓𝑓(𝑡𝑡) is

time fluctuation factor of neutron production rate normalized as unity, and φ𝜃𝜃𝑖𝑖 is neutron fluence during theirradiation at 𝜃𝜃𝜄𝜄 degrees. Finally, φ𝜃𝜃𝑖𝑖 is derived as following equation (Eq. 2) .
φ𝜃𝜃𝑖𝑖 =𝐶𝐶𝛾𝛾,𝜃𝜃𝜄𝜄
𝑡𝑡𝑖𝑖
𝑁𝑁0 ∫𝐸𝐸 𝜎𝜎(𝐸𝐸)𝑃𝑃(𝐸𝐸)𝜃𝜃𝑖𝑖 𝑑𝑑𝐸𝐸 ∫0 𝑓𝑓(𝑡𝑡)𝑘𝑘 𝜆𝜆𝑡𝑡 𝑑𝑑𝑡𝑡 × 𝑘𝑘 −𝜆𝜆(𝑡𝑡𝑖𝑖 +𝑡𝑡𝑐𝑐) × (1 − 𝑘𝑘 −𝜆𝜆𝑡𝑡𝑚𝑚 ) × 𝐼𝐼𝑟𝑟 × 𝑓𝑓𝑛𝑛 × 𝑓𝑓𝑔𝑔 × 𝜀𝜀

(Eq. 2)

Finally, the total produced neutron intensity Φtot is calculated by integrating experimental neutron flux

angular distribution, as Eq. 3,

Φtot = ∑𝑖𝑖=𝑚𝑚𝑚𝑚𝑚𝑚
𝑖𝑖=1

𝜃𝜃𝑖𝑖

∫

𝜃𝜃𝑖𝑖−1φ𝜃𝜃𝑖𝑖 ∙ 2πr2 sin 𝜃𝜃 𝑑𝑑𝜃𝜃 ,where r is distance between neutron source and measurement point.

(Eq. 3)

2.2 Measurement procedure

The schematic experimental arrangement is shown in Fig. 1. We installed 11 indium foils, which were

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JAEA-Conf 2023-001

10 mm× 10 mm × 0.5 mm, on a polystyrene jig at 10 cm
away from the center of the target from 0° to 150° by 15°
intervals.
In this experiment, we irradiated with DD neutron forabout 8 hours. Accelerated deuteron energy was 250 keV
and the deuterons were bombarded the deuterium-loaded
titanium target with 1 mA beam current to induce D(d,n)3He reaction. A time fluctuation factor of neutron Fig. 1.
production rate 𝑓𝑓(𝑡𝑡) was measured by an 238U fission chamber installed during the irradiation. We repeatedthis irradiation experiment 3 times and measured radio-activities of these activated indium foils withgermanium detectors. Finally, we calculated the angular distribution of neutron flux intensity and total

neutron production intensity from these measured results.
2.3 Simulation of angular distribution of neutron flux intensity
After the experiment, we carried out a simulation of the real measurement to confirm validity of thepresent experimental results, and to consider the better simulation methods.
At first, we calculated deuterium ions behavior in a titanium target by using the Stopping and Range ofIons in Matter (SRIM) [8], which can calculate the deuteron path way and energy loss in the materials. Fig.2
shows an example of deuteron path ways calculated by SRIM, with 1000 deuterium ions for the incident
energy of 250 keV.
After that, we calculated a neutron source term, i.e., the angular
distribution and the neutron spectra for each emission angle, considering
the deuterium ions behavior in a titanium target (Fig. 3). D(d, n)3He crosssection and characteristics of produced neutron by the reaction was derived
by Drosg-2000 [9]. The DD neutrons emission angle θ from thedeuterium beamline direction can be expressed in the following equation.
𝜃𝜃 = |𝜂𝜂 − 𝜑𝜑| ~ 𝜂𝜂 + 𝜑𝜑,

where η is the deuterium scattering angle, and φ is the DD neutron Fig. 2. Path way of deuterium
emission angle with respect to the incident deuteron beam axis.

ions (1000pcs.) by SRIM

neutronFinally, we calculated the angular distribution of neutron flux

intensity in the real experiment by A General Monte Carlo N-Particle
simulation results. Since the present experimental data cannot be converted
to cross section data due to lack of detailed target information such as

𝜑𝜑250keV～～transport code (MCNP5) [10], and compared the experimental and

SRIM

D-ion
E keV
(x, y, z)

𝜂𝜂

DD

𝜃𝜃

reaction

Drosg-2000

deuterium density, we normalized the calculated result by average Φtot Fig. 3. The simplified diagramof the SRIM and Drosg-2000
value of three experimental results.
combination- 48 48

JAEA-Conf 2023-001

4.0

le 6
Experiment 1
Experiment 2
Experiment 3
Experiment average
Simulation (Legendre)
Simulation (Drosg-2000)
Fitting curve

Neutron flux [n/cm2/s/mA]

3.5

3.0
2.5
2.0
1.5
1.0

①

0.5
0.0

0

15

30

45

60

②

75 90 105 120 135 150 165 180
Angle [degree]

Fig. 4.

3.

Results and discussion
Measured angular distributions of neutron flux intensity byexperimental and simulation results are shown in Fig. 4. The
horizontal axis represents the measured angle in the laboratory
system. Three dot series with error bars show the experimental
values of the neutron flux intensity in the present study. The
green solid curve means the average neutron flux of threeexperimental values, and the red solid curve indicates thecalculated values by MCNP5. As a result, no significant
difference was found at less than 135° (area ①) between values

Fig. 5.

of experiments and simulation. On the other hand, at 150° (area②), the simulated intensity was smaller than the experimental
result. This discrepancy seemed to be caused by a reason: D(d, n)3He cross-section installed in Drosg-2000.
Fig. 5 shows D(d, n)3He cross-sections in Drosg-2000 (black solid curve) and measured DD crosssection in the past studies listed in EXFOR [11-14] (colored plots). This graph shows that measured DD crosssections appears to have a symmetric curve with respect to 90° at lower deuterium beam energies. However,the cross-section data in Drosg-2000 shows higher values in forward angles than in backward angles.
Therefore, we calculated new theoretical cross sections and used it to calculate the neutron angular
distribution again. In general, the angular distribution of the D(d, n)3He reaction products can be expressedby as an expansion in terms of even Legendre polynomials, as shown in Eq. 4, because the projectile andtarget are symmetric about the 90° center of mass angle.
𝑑𝑑𝜎𝜎(90°)𝑑𝑑𝜎𝜎[1 + 𝐴𝐴 cos2(𝜃𝜃) + 𝐵𝐵cos 4(𝜃𝜃)],=𝑑𝑑 cos 𝜃𝜃
𝑑𝑑 cos 𝜃𝜃(Eq. 4)

where 𝐴𝐴 and 𝐵𝐵 are the energy dependent asymmetry coefficients. In case of OKTAVIAN deuteron beam,

which has about 250 keV energy, 𝐴𝐴 was 1.32 ± 0.04 and 𝐵𝐵 was 0.43 ± 0.05 [15]. After that, we

calculated D(d, n)3He cross sections by using Eq. 4 as shown in Fig. 5, the solid brown curve. Absolute values- 49 49

JAEA-Conf 2023-001

of cross section were adjusted so that the 90° value corresponds toD(d, n)3He cross section at 90° in Drosg-2000. The newly derived
cross sections with the Legendre polynomials showed smaller value
in the forward angle and larger in the backward angle than the crosssections calculated with Drosg-2000, and had good agreement withthe experimental results by A.S. Ganeev [12] near the 250 keV ofincident deuterium energy.
New-built neutron source term calculated with the new crosssections is shown as the solid blue curve in Fig. 4, and this result
showed a good agreement with present ex perimental values thanthe previous simulation result at more than 150 degrees. Therefore,
we confirmed that the current experimental results are reasonable
compared to previous experimental results by using this theoreticalcross section data calculated from Legendre polynomials.
Finally, we revealed the DD neutron production intensity ofof neutron intensity, φ𝑡𝑡𝑡𝑡𝑡𝑡 × 𝑓𝑓(𝑡𝑡), for each experiment, and Fig.7

shows the histogram of the generated neutron intensity from theseresults. We found that OKTAVIAN can generate DD neutrons with

(2.00.1)×109 n/mC in average.

4.

Conclusion

Number of detections [-]OKTAVIAN. We used the black dotted fitting curve shown in the Fig. 6. Time fluctuation of neutron
Fig. 4 as φ𝜃𝜃𝑖𝑖 , combining experimental data less than 150° and intensity for each of the threeexperiments
calculated new values above 150°. Fig. 6 shows the time fluctuation
5000

4500
4000
3500
3000
2500
2000
1500
1000
500

le 9

0

0.0

2.0

Neutron intensity [n/mC]

4.0

Fig. 7. Histogram of neutron
intensity

In this study, we measured the angular distribution of DD neutron flux intensity from 0° to 150° by 15°
intervals, and compared with numerically calculated result by SRIM, Drosg-2000 and MCNP5 to examine
the agreement of the present result with cross section past experimental results, the accuracy of neutron source
term and the validity of simulation methods. As a result, no significant difference was found less than 135°
between results of experiments and simulation. Also we found that DD neutron intensity was (2.0 0.1)×
109 n/mC by OKTAVIAN. On the other hand, at 150°, the simulated intensity was much smaller than theexperimental result and found the probability that cross-section data in Drosg-2000 have some problem. In
order to consider this problem, we derived theoretical DD cross-sections from the Legendre polynomials,
and performed neutron transport calculation again. As a result, the newly produced cross sections werereasonable in comparison with previous experimental results, and a good agreement was found with thepresent experimental values. Therefore, we found that the current experimental results were valid comparedto past experimental results by using theoretical cross section data calculated from Legendre polynomials.
In the future, we will investigate a new method to measure neutron intensity for angles larger than 150°,- 50 50

JAEA-Conf 2023-001

and evaluate the accuracy of DD reaction cross section values in the whole emission angles. And in future
we will also investigate the method to measure the DD neutron spectrum.

References[1] TAMAKI, Shingo, et al. "Radioactivation Analysis of Concrete Wall in OKTAVIAN Facility." Plasma
and Fusion Research 17 (2022): 1405001-1405001.
[2] Lee, Yi-Kang. "Analysis of the tritium breeding ratio benchmark experiments using the Monte Carlocode TRIPOLI-4. "Fusion engineering and design 85.7-9 (2010): 1125-1128.
[3] Asnal, M., T. Liamsuwan, and T. Onjun. "An evaluation on the design of beam shaping assembly basedon the DT reaction for BNCT." Journal of Physics: Conference Series. Vol. 611. No. 1, 2015.
[4] R.C. Caldwell et al. “Activation analysis in petroleum exploration research”, Nuclear Instruments andMethods (1959).
[5] Chichester, D., J. Simpson, and M. Lemchak. "Advanced compact accelerator neutron generator
technology for active neutron interrogation field work." Journal of Radioanalytical and Nuclear
Chemistry 271.3 (2007): 629-637.
[6] Yan, M. F., et al. "Optimization design of a fast neutron imaging collimator by genetic algorithm."
Journal of Instrumentation 15.12 (2020).
[7] O. Iwamoto, N. Iwamoto, K. Shibata, A. Ichihara, S. Kunieda, F. Minato, and S. Nakayama, "Status of
JENDL", EPJ Web of Conferences, 239, 09002_1-6 (2020).
[8] Ziegler, James F., Matthias D. Ziegler, and Jochen P. Biersack. "SRIM–The stopping and range of ionsin matter (2010)." Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions
with Materials and Atoms 268.11-12 (2010): 1818-1823.
[9] Drosg, M. DROSG-2000: Neutron source reactions. Data files with computer codes for 56
monoenergetic neutron source reactions. No. IAEA-NDS--87 (REV. 5). International Atomic Energy
Agency, 2000.
[10] Brown, F.B., MCNP-A General Monte Carlo N-Particle Transport Code, Oak Ridge(US): Los Alamos
National Laboratory; 2003.
[11] Data, Experimental Nuclear Reaction. "EXFOR." CSISRS https://www-nds.iaea.org/exfor (2022).
[12] A.S.Ganeev, “The D-D reaction in the deuteron energy range 100 - 1000 keV.”, Soviet Atomic Energy,
Supplement, Issue.5, p.21 (1957), USA.
[13] N.Ying, “A Study of the 2H (d, p)3H and 2H (d, n)3He Reactions and the Excited State of 4He at 23.9
MeV”, Nuclear Physics, Section A, Vol.206, Issue.3, p.481 (1973), Netherlands.
[14] V.V.Volkov, “Investigation of the D-D reaction in the deuteron energy range 0.20 to 1.75 MeV”, Soviet
Atomic Energy, Supplement, Issue.5, p.13 (1957), USA.
[15] Theus, R. B., W. I. McGarry, and L. A. Beach. "Angular distributions and cross-section ratios for thereactions 2H (d, n) 3He and 2H (d, p) 3H below 500 keV." Nuclear Physics 80.2 (1966): 273-288.

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7.

Production cross sections of 198gAu in proton-induced reactions
on natural platinum
Gantumur DAMDINSUREN1,2*, Masayuki AIKAWA1,3,4, Khishigjargal
TEGSHJARGAL2, Norov ERDENE2, Naoyuki UKON5, and Hiromitsu HABA 6

1

Graduate School of Biomedical Science and Engineering, Hokkaido University, Sapporo 060 8638, Japan
2

School of Engineering and Applied Sciences, National University of Mongolia, Ulaanbaatar
14201, Mongolia
3 Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
4 Global Center for Biomedical Science and Engineering, Faculty of Medicine, Hokkaido

University, Sapporo 060-8648, Japan
5

Advanced Clinical Research Center, Fukushima Medical University, Fukushima 960-1295, Japan
6 Nishina Center for Accelerator-Based Science, RIKEN, Wako 351-0198, Japan*Email: damdinsuren@nds.sci.hokudai.ac.jp

The production cross sections of the natPt(p,x)198gAu reaction were measured at the AVF cyclotronof the RIKEN RI Beam Factory. The stacked-foil activation technique and high-resolution γ-ray
spectrometry were adopted to derive the cross sections. The derived cross sections were compared withexperimental data studied earlier and with the theoretical calculation in the TENDL-2019 library.

1. Introduction
The radionuclide 198gAu has a half-life of 2.6941 d and is a beta emitter (β-: 100%, <Eβ-> = 312.5keV) [1]. 198gAu is widely used for therapy in nuclear medicine [2,3]. There are several production routes
for 198gAu production. One of the possible production routes is the proton-induced reaction on platinum
targets. In this study, we focused on the proton-induced reaction on natPt targets. Two previous
experimental studies were found in the literature survey [4,5]. However, their data show large
uncertainties and discrepancies. Therefore, we measured the excitation function of the natPt(p,x)198gAu
reaction. The result was compared with earlier studies and theoretical calculation in the TENDL-2019
library [6].

2. Experimental method
The experiment was performed at the AVF cyclotron of the RIKEN RI Beam Factory. The stacked foil activation technique and high-resolution γ-ray spectrometry were adopted to measure the crosssections.
The stacked target consisted of pure metallic foils of natPt (20 μm thick, 99.95% purity, 100×100- 52 -

JAEA-Conf 2023-001

mm size), and natTi (5 μm thick, 99.6% purity, 50×100 mm size), which were purchased from Nilaco
Corp., Japan. The natTi foil was used for the natTi(p,x)48V monitor reaction to assess beam parameters andtarget thicknesses. The size and weight of the foils were measured to determine the average thicknesses.
The derived thicknesses of the natPt and natTi foils were 39.2 and 2.24 mg/cm2, respectively. The foils
were cut for the size of 10×10 mm to fit a target holder, which served as a Faraday cup. Twenty-five setsof Pt-Pt-Ti-Ti foils were stacked into the target holder.
The stacked target was irradiated with a proton beam for 30 min. The incident beam energy wasmeasured by the time-of-flight method [7] and found to be 30.1±0.1 MeV. The energy degradation in thestacked target was calculated using stopping powers derived from the SRIM code [8]. The average beam
intensity was 101 nA, which was measured by the Faraday cup.
γ rays emitted from each irradiated foil were measured by a high-resolution HPGe detector (ORTEC
GEM-25185-P). The detector was calibrated by a multiple γ-ray emitting point source. The spectra wereanalyzed by dedicated software (Gamma Studio, SEIKO EG&G). The dead time was kept less than 4.7%
during the measurement.
Cross sections of the natTi(p,x)48V monitor reaction were determined to assess the beam parameters
and target thicknesses. The cross sections were derived from measurements of the 983.5-keV γ ray (Iγ =99.98%) emitted with the 48V decay (T1/2 = 15.9735 d). The result was compared with the IAEA
recommended values [9,10] in Fig. 1. The derived excitation function of the natTi(d,x)48V reaction was ingood agreement with the IAEA-2007 recommended values. The measured beam parameters and target
thicknesses without any correction were used to determine the cross sections of the natPt(p,x)198gAu
reaction.

Fig. 1. The excitation function of the natTi(p,x)48V monitor reaction with the recommended
values [9,10].

3. Result and discussion
The cross sections of the natPt(p,x)198gAu reaction were derived from the measurement of the411.80205-keV γ line (Iγ = 95.62%) in the decay of 198gAu. The derived cross sections are shown in Fig.
2 in comparison with the previous experimental data and the theoretical estimation of the TENDL-2019
library. Our result is consistent with the previous experimental data within the uncertainty although thedata by Tárkányi et al. (2004) deviated at 17-23 MeV. The TENDL-2019 data show a similar trend to the- 53 53

JAEA-Conf 2023-001

experimental cross sections while its peak position is slightly lower.

Fig. 2. Excitation function of the natPt(p,x)198gAu reaction with the previous experimental data [4,5] andthe TENDL-2019 data [6].

4. Conclusions
The excitation function of the natPt(p,x)198gAu reaction was measured up to 30 MeV. The wellestablished methods, the stacked-foil activation method and γ-ray spectrometry were used for the crosssection measurement. The derived cross-section data of the natPt(p,x)198gAu reaction is consistent with thedata of Tárkányi et al. (2004) [4] and Showaimy et al. (2019) [5] within the uncertainty.

Acknowledgments
The experiment was performed at RI Beam Factory operated by RIKEN Nishina Center and CNS,
University of Tokyo, Japan. G. Damdinsuren was granted a scholarship by the M-JEED project(Mongolian-Japan Engineering Education Development Program, J11B16). This work was partially
supported by JSPS KAKENHI Grant No. 22H04961.

References[1] Huang X & Kang M, Nuclear Data Sheets for A = 198, Nucl. Data Sheets, 2016, 133, 221-416.
[2] Konishi M, Fujita M, Takeuchi Y, et al., Treatment outcomes of real-time intraoral sonographyguided implantation technique of 198Au grain brachytherapy for T1 and T2 tongue cancer, J.
Radiat. Res., 2021, 62, 871–876.
[3] Chakravarty R, Chakraborty S, Guleria A, et al., Clinical scale synthesis of intrinsicallyradiolabeled and cyclic RGD peptide functionalized 198Au nanoparticles for targeted cancer
therapy, Nucl. Med. Biol., 2019, 72, 1-10.
[4] Tárkányi F, Hermanne A, Takács S, et al., Cross sections for production of the therapeutic
radioisotopes 198Au and 199 Au in proton and deuteron induced reactions on 198Pt, Radiochim Acta,
2004, 92, 223-228.
[5] Showaimy H, Solieman A.H.M, Hamid A.S.A, et al., Measurements of activation cross sections
for proton induced reactions on natural platinum targets leading to the formation of gold
radioisotopes, Radiat. Phys. Chem., 2019 157, 97-101.
[6] Koning A.J, Rochman D, Sublet J-C, et al., TENDL: Complete Nuclear Data Library for- 54 54

JAEA-Conf 2023-001

Innovative Nuclear Science and Technology, Nucl. Data Sheets, 2019, 155, 1–55.
[7] Watanabe T, Fujimaki M, Fukunishi N, et al., Beam energy and longitudinal beam profile
measurement system at the RIBF, Proc. 5th Int. Part. Accel. Conf. (IPAC 2014), 2014, 3566–
3568.
[8] Ziegler J.F, Ziegler M.D, Biersack J.P, SRIM - The stopping and range of ions in matter, Nucl.
Instrum. Methods. Phys. Res. B, 2010, 268, 1818–1823.
[9] Tárkányi F, Takács S, Gul K, et al., Charged Particle Cross-Section Database for Medical
Radioisotope Production: Diagnostic Radioisotopes and Monitor Reactions (updated version),
Availablefrom:https://wwwIAEA-TECDOC-1211[Internet],
2007,
nds.iaea.org/medical/medical-2020-05/monitor_reactions.html.
[10] Hermanne A, Ignatyuk A.V, Capote R, et al., Reference Cross Sections for Charged-particle
Monitor Reactions, Nucl. Data Sheets, 2018, 148, 338–382.

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JAEA-Conf 2023-001

8.

Preliminary experiment for measurement of radionuclide yieldfrom nuclear capture reaction of negative muon

Yuji YAMAGUCHI1*, Masahide HARADA1, Naritoshi KAWAMURA 2, Izumi UMEGAKI2,
Motonobu TAMPO 2, Soshi TAKESHITA 2, and Katsuhiro HAGA1
1J-PARC Center, Japan Atomic Energy Agency
2-4 Shirakata, Tokai-mura, Naka-gun, Ibaraki-ken 319-1195, Japan
2High Energy Accelerator Research Organization

1-1 Oho, Tsukuba-shi, Ibaraki-ken 305-0801, Japan*Email: yamaguchi.yuji@jaea.go.jp

We have performed a preliminary experiment to check applicability of existing methodology totaking comprehensive data of radionuclide yields from nuclear capture of a negative muon ( −) for
wide range of target atomic number. The radionuclide yields per stopped − are obtained byspectroscopy of -rays and X-rays from targets of 27Al, 59Co, 141Pr, and 209 Bi using high-purity
germanium detectors. It is confirmed that the methodology can be applied to obtain the comprehensivedata.

1. Introduction
A negative muon (−) is known to be captured by a nucleus, 𝐴𝐴𝑍𝑍N(−, ) 𝑍𝑍−1𝐴𝐴N*, after the muoncascades down to 1s state of the muonic atom with emitting characteristic X -rays called muonic X-rays

and Auger electrons. The nuclear capture reaction competes with the − free decay (− → e− + 𝜈𝜈̅e + )
and is dominant for the nucleus with atomic number Z > 12. After the nuclear capture, a highly excitednucleus is produced because a part of the muon mass of 106 MeV/c 2 is converted to the excitationenergy, and is deexcited with emitting neutrons, -rays, and sometimes charged particles to reach astable nucleus or a radionuclide. In this way, an irradiated sample by a large amount of − can be
activated.
Materials and Life Science Experimental Facility (MLF), J-PARC provides intense pulsed − beamfor various researches such as non-destructive isotopic analysis, negative muon spin rotation andrelaxation (−SR), and so on [1-3]. To handle irradiated samples properly at MLF, it is necessary toestimate radioactivity of the irradiated samples accurately for the sake of radiation safety. Recently, an
activation calculation code based on particle transport simulation by Particle and Heavy Ion Transport
code System (PHITS) [4] has been established to estimate radioactivity of the irradiated samples at
MLF. Because reliability of the estimated radioactivity relates to radiation safety of MLF, PHITS
calculation needs to be verified for radionuclide production in targets with wide range of Z.
To verify the calculation results, comprehensive experimental data of radionuclide production from- 56 56

JAEA-Conf 2023-001

nuclear capture of − are required for wide range of target Z. However, most of the experiments were
performed to take only the data of the target of interest for their specific purposes. It is also known that
there exist discrepancies between experimental data and calculation results by PHITS. Therefore, wehave started to measure the yield of radionuclide from nuclear capture of − for wide range of target Z
In this paper, we report on the preliminary experiment performed at MLF to check applicability ofexisting methodology to taking comprehensive data of radionuclide yield for wide range of target Z.

2. Experiment
The experiment was performed at D2 area ofmuon science facility in MLF. The plan view ofthe experimental setup is shown in Figure 1. A
pulsed − beam was generated by a 3-GeV proton
beam on a 20-mm-thick graphite target and wasprovided through decay muon beamline (D-line).
Incident negative muons from the D-line wereextracted through the thin Kapton beam windowat D2 area with momentum of 35 MeV/c. The
extracted negative muons flew in the air andstopped in a target.

Figure 1. Plan view of experimental setup.
Incident negative muons with 35 MeV/c comeThe targets used in this experiment are listed
in Table 1. They were square-shaped plates thickfrom the upper side of this view.
Table 1. List of targets.
Size Thickness Purity
Target
[mm]
[mm]
[%]

enough to stop incident negative muons and wereselectedfrommonoisotopic

elementsforsimplicity of the measurement and analysis. Each

27Al

target was irradiated for about 10 hours at

59Co

− beam intensity of 3×103 s-1 to measure the141Prradionuclide yield per stopped −.
The yield of radionuclide and the number of

209Bi

50×50
50×50

2.0
1.0

99
99.9

25×25
60×60

1.0
1.0

99
99.9

stopped − were obtained by -ray and X-ray
spectroscopy, respectively. The -rays from radionuclides and muonic X-rays were measured in-beamusing high-purity germanium (HPGe) detectors (ORTEC GMX Series) with a 51-mm diameter window.
Two detectors were applied because the detection time distribution was different between -rays andmuonic X-rays due to the pulsed beam. The HPGe detector for muonic X-rays was placed at 50 cm far
from the target to avoid pile-up of the signal. The detector for -rays was closer to the target than thatfor muonic X-rays to obtain -ray spectra efficiently. The -rays from radionuclides with half-life longer
than typically 15 hours were measured off-line using a lead-shielded HPGe detector. To calibrate theabsolute energy scales for the HPGe detectors, measurement of -rays from 152Eu check source was also
performed.

3. Analysis
The energy spectra measured in-beam and off-line -spectroscopy for 27Al target are shown in
Figure 2 and Figure 3, respectively. In Figure 2, -rays from radionuclides produced by − nuclear
capture are clearly observed at 844 and 1014 keV ( 27Mg), and 1809 keV ( 26Na). Background peaks from- 57 57

JAEA-Conf 2023-001

Figure 2. Energy spectrum measured in-beam

Figure 3. Energy spectrum of -rays measured
off-line for 1 hour after irradiation of 27Al

-spectroscopy using 27Al target. The identified
radionuclides are shown.

target. The single and double escape peaks
from the 2754-keV -rays from 24Na are also
shown.

natural radionuclides are also observed such as 208Tl, 228Ac, 214Bi, and 40K because the HPGe detector
used in-beam measurement was not shielded. In Figure 3, -rays from 24Na are clearly observed at 1369
and 2754 keV in addition to those from 27Mg at 844 and 1014 keV.
The yield of radionuclide produced by − nuclear capture Y was obtained by−1(4𝜋𝜋Ω−1 )𝜀𝜀 −1 𝐼𝐼 −1 (e−μ𝑡𝑡eff )−1𝑇𝑇irr
𝐶𝐶γ 𝑇𝑇irr
for in-beam
𝑌𝑌 = 𝑝𝑝𝑇𝑇irr = {−1(4𝜋𝜋Ω−1)𝜀𝜀 −1 𝐼𝐼 −1 (e−μ𝑡𝑡eff )−1 𝑇𝑇cor
𝐶𝐶γ 𝑇𝑇irr
for off-line,(1)

where p is production rate, Tirr is irradiation time,  issolid angle, I is emission rate of the -ray of interest, and is attenuation coefficient. The effective thickness ofthe target for photons teff is expressed by
𝑡𝑡eff =

𝑡𝑡range,cos 70°(2)

where trange is range of incident − in the target. The net
count of the -ray of interest C was obtained by fitting
using Gaussian functions. A typical example of thefitting is shown in Figure 4. The correction for cooling
Tcor is written as
𝑇𝑇irr

𝑇𝑇off

𝑇𝑇ms

𝑇𝑇
1 𝑇𝑇
1 𝑇𝑇
1 𝑇𝑇
𝑇𝑇cor =
{1 − ( ) } ( ) {1 − ( ) },
ln2
2
2
2

(3)

where T is half-life, Toff is the period from irradiation
stop to measurement start, and Tms is measurement time.

Figure 4. Fitting result for the peak at
844 keV from 27Mg in Figure 2. Black
line: Observed spectrum. Red line:
fitting curve using Gaussian function.
The net count C is obtained
integrating the shaded area.

by

The detection efficiency of the HPGe detector  was obtained by particle transport simulation using
PHITS. The geometry of the system for the simulation is shown in Figure 5. The origin corresponding
to the target position is defined as the photon source position. The photon source has Gaussian spatial
distribution in x and y directions and is rotated 70° around y-axis. The Gaussian functions for x and y
directions are independent each other and are assumed to have x = 6.7 mm and y = 11.7 mm. Photons- 58 58

JAEA-Conf 2023-001

Figure 5. Geometry of the system for thesimulation. Photon flux is also drawn with

Figure 6. Model of the HPGe detector.

color cluster plot to show the photon source
position.
from the source enter the HPGe detector on z-axis through its thin entrance window. The model of the
HPGe detector is shown in Figure 6. The HPGe detector is a coaxial detector and has a beryllium
window with a diameter of 51 mm and a thickness of 510 m in front of the crystal. The Ge crystal has
0.3-m-thick ion implanted and 700-m-thick lithium diffused dead layers. The obtained efficiency  isshown in Figure 7 as a function of photon energy. The photon energy range of 25 to 2800 keV waschosen in the calculation according to the energy required for the analysis.
The X-ray energy spectrum from 340 to 460 keV for 27Al target is shown in Figure 8. KX-ray
peaks are clearly observed from 2p→1s to 6p→1s in this figure. The number of stopped  −  − can beobtained by

− = (4 -1) −1(e-teff)-1CKX,(4)where CKX is sum of net count of the KX-rays. However, KX-rays from heavy targets cannot bemeasured efficiently because they have high energy of several MeV. Thus,  − for 141Pr and 209Bi
targets was obtained, assuming that  − is proportional to the number of protons on the graphite target,

Figure 7. Detection efficiency of the HPGe
detector calculated by PHITS. The efficiency
in 25 to 2800 keV is shown.

Figure 8. Energy spectrum of X-rays for 27Al
target in the range of 340 to 460 keV. KX-ray
transitions are shown from 2p→1s to 6p→1s.

- 59 59

JAEA-Conf 2023-001by𝐼𝐼𝜇𝜇− =𝜙𝜙
𝐼𝐼 −𝜙𝜙C 𝜇𝜇 ,C(5)

where  is the number of protons on the graphite target. The symbols with the index C are reference
values obtained using a 3-mm-thick carbon target. The number of stopped  − in the C target  −, C was
obtained from Equation (4).

4. Results and discussion
Typical results of radionuclide yields per stopped − are shown in Figure 9. The present data areconsistent with the data by Heisinger et al. [5] within experimental uncertainties.
The present data include not only statistical uncertainty but also systematic uncertainties of solid
angle and detection efficiency. The estimated uncertainty of solid angle ranges 8%-16% because thetarget was set on the detector at zero distance for off-line measurement while was set away fromdetectors in-beam. The estimated uncertainty of detection efficiency is 8% from the simulation. The
uncertainties of solid angle and detection efficiency can be reduced by  counting using a check source.
In Figure 10, calculation/experiment (C/E) values are shown to compare present data withcalculation results by PHITS ver.3.20. Although PHITS results tend to underestimate present data,
further data covering wide range of target Z with lower uncertainty are needed to discuss thediscrepancy in detail and to verify the calculation results more accurately.

Figure 9. Radionuclide yields per stopped
−.

Shaded bar: Present data. White bar:PHITS3.20 results. Black bar: Heisinger et
al. [5].

Figure 10. Calculation/experiment (C/E)
value of the radionuclide yield in Figure 9.
Calculations are PHITS3.20 results andexperiments are present data.

5. Summary
We performed the preliminary experiment to check applicability of existing methodology to taking
new data set of radionuclide yield for wide range of target Z. It was confirmed that present data obtainedusing existing methodology were consistent with data by Heisinger et al. Present data were also
compared with calculations by PHITS3.20. Although discrepancy between present data and PHITS
calculation was observed, further data covering wide range of target Z with lower uncertainty are- 60 60

JAEA-Conf 2023-001

needed to discuss the discrepancy in detail and to verify the calculation results more accurately.

References1)

Umegaki, I., et al., Nondestructive High-Sensitivity Detections of Metallic Lithium Deposited2)

on a Battery Anode Using Muonic X-rays, Anal. Chem., vol.92, no.12, 2020, pp.8194-8200.
Ninomiya, K., et al., Development of non-destructive isotopic analysis methods using muon
beams and their application to the analysis of lead, J. Radioanal Nucl Chem, vol.320, 2019,
pp.801-805.

3)Sugiyama, J., Nuclear Magnetic Field in Solids Detected with Negative-Muon Spin Rotation
and Relaxation, vol.121, 2018, 087202.

4)

Sato, T., et al., Features of Particle and Heavy Ion Transport code System (PHITS) version
3.02, J. Nucl. Sci. Technol., vol.55, 2018, pp.684-690.

5)

Heisinger, B., et al., Production of selected cosmogenic radionuclides by muons: 2. Capture ofnegative muons, Earth and Planetary Science Letters, vol.200, 2002, pp.357-369.

Acknowledgments
The muon experiment at the Materials and Life Science Experimental Facility of the J-PARC was
performed under a user program (Proposal No. 2021B0356).

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JAEA-Conf 2023-001

9. Cross Comparison of Neutron Spectra with Liquid
Scintillator and Bonner Sphere Spectrometer
Eunji Lee†1,2, Toshiya Sanami1,2, Tetsuro Matsumoto3, Akihiko Masuda3,
Nobuhiro Shigyo4, Tsuyoshi Kajimoto5, Noriaki Nakao6, Robert Froeschl7,
Elpida Iliopoulou∗7 , Angelo Infantino7, and Stefan Roesler7
1

High Energy Accelerator Research Organization (KEK), Oho, Tsukuba, Ibaraki
305-0801, Japan
2
The Graduate University for Advanced Studies (SOKENDAI), Hayama, Kanagawa
240-0193, Japan
3
National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono,
Tsukuba, Ibaraki 305-8560, Japan
4

Department of Applied Quantum Physics and Nuclear Engineering, Kyushu University,
Motooka, Nishi-ku, Fukuoka 819-0395, Japan

5

Hiroshima University, 1-4-1, Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8527, Japan
6
Shimizu Corporation, 3-4-17 Etchujima, Koto-ku, Tokyo 135-8530, Japan
7
CERN, 1211 Geneva 23, Switzerland†
Email: eunji.lee@kek.jp

Abstract
Experimental measurements were performed for produced high-energy neutrons when the
24 GeV/c proton beam hit a copper target at the CHARM facility in the East Hall of the
CERN proton Synchrotron. Neutron energy spectra after concrete and steel shields were
measured with a liquid scintillator and a Bonner sphere spectrometer under an identicalshielding configuration. The light output distribution of the liquid scintillator and a set ofcount rates of the Bonner sphere spectrometer based on the 3 He proportional counter wasconverted into the neutron energy spectrum using the unfolding method with a calculated
response matrix for each instrument, respectively. An initial guess of the neutron energy
spectrum for unfolding was obtained by the PHITS code. The neutron energy spectra were
derived to inter-compare the difference between two measurement methods.

1

Introduction

Production of neutrons is an unavoidable consequence of operating high-energy accelerator
facilities. The neutrons have a wide energy range, from thermal to beam energy. From theviewpoint of radiation protection, neutron spectrum after penetrating a shield is importantin the shielding design of high-energy accelerator facilities. Monte Carlo codes can provide anestimation of neutron spectrum in accelerator facilities even for complicated shielding structures.
However, accuracies of the codes for the high-energy neutrons generated by the high-energy
beam, especially above 1 GeV, are not well evaluated since comparable experimental data are∗

Present address: Hirslanden Private Hospital Group, Radiation Oncology Institute, Lausanne Switzerland- 62 62

JAEA-Conf 2023-001

scarce [1]. Therefore, the lack of experimental data in the high-energy region requires newexperimental data with a simplified shielding structure.
For high-energy neutrons, a liquid scintillator and a Bonner sphere spectrometer (BSS)
are widely used as measurement methods. The scintillator has an energy response of up to afew hundred MeV, but the efficiency decreases with neutron energy. In order to detect highenergy neutron, mostly a larger volume detector is used. This requires to increase the detection
threshold to avoid large counting rate, resulting in the rejection of lower energy neutrons. On
the other hand, the BSS has a wide energy response from thermal up to 20 MeV. To extend theupper energy range up to a few hundred MeV, concentric spherical shells of copper and lead areused to add (n, xn) reactions in the higher energy region. However, the BSS cannot provide theneutron energy spectrum without an initial guess spectrum.
In this study, with the use of the unfolding method, we experimentally derived the neutronenergy spectra, including high-energy neutrons above 10 MeV, obtained by two measurement
methods under the identical shielding configuration. The neutron spectra were measured byusing different shielding materials of concrete and steel. The initial guess neutron spectra were
derived using the Monte Carlo code, PHITS [2], by introducing each shielding condition.

2

Experiment

2.1

CHARM Facility

Figure 1: Schematic cross-sectional view of the CHARM facility.
Figure 1 shows an example of the experimental setup for concrete 40 cm in thickness of the
CHARM facility in the east hall of CERN.
The facility received pulsed 24 GeV/c proton beam from the CERN proton synchrotron(PS) with an intensity of 1 × 109 to 5 × 1011 protons per pulse and a pulse length of 350
ms. The protons hit a cylindrical copper target of 8 cm in diameter and 50 cm in length in
the irradiation room. The protons passing through the target were stopped by an iron beam
dump. The irradiation room was surrounded by concrete and iron shield, except for the beam
path and the entrance. The beamline was 129 cm in height from the floor. The bulk shielding
structure above the ceiling of the irradiation room consisted of a 10-cm-thick marble, a 40-cm-- 63 63

JAEA-Conf 2023-001

thick iron slab, and concrete blocks with a total thickness of 360 cm. In the direction above
the target, a hole duct called material test location is created (see Fig. 1). Here, one can freely
configure any shielding materials made of concrete and steel. The neutron detectors were placedon the top position of the material test location by using metal grating. Densities of concrete,
barite concrete, iron, and marble materials are 2.4, 3.35, 7.2, and 2.71 g/cm3 , respectively. The
experimental setup for the steel with 40 cm was obtained by replacing concrete blocks shown infigure 1. The concrete and steel blocks have cross-sections with 77.2 cm × 77.2 cm and 78 cm
× 78 cm, respectively. The densities of concrete and steel blocks used as material test blocks
were 2.23 g/cm3 and 7.77 g/cm3 .

2.2

Neutron detector

Figure 2: Picture of neutron detector set-up. The liquid scintillator (Left) and the Bonner
sphere spectrometer (Right) were installed as the neutron detector. Two concrete blocks with
20-cm-thickness were used to fix the metal grating.
Neutrons were measured using the neutron detectors, an NE213 liquid organic scintillator
and a BSS, placed on a metal grating positioned on the top roof. A picture of the detectors
is presented in figure 2. The liquid scintillator was filled in a cylindrical-shaped aluminum
container 12.7 cm in both diameter and length. The scintillator was supported by an acrylic
structure, at 5 cm above the surface of the metal grating. In the 5 cm space beneath the NE213
detector, an NE102A plastic scintillator of dimensions 15 × 15 × 0.6 cm was inserted as a VETO
detector (VETO1) to remove charged particle events. Another NE102A plastic scintillator of
dimensions 15 × 15 × 0.3 cm surrounded the NE213 detector as an additional VETO detector(VETO2). The BSS consisted of a 3 He spherical proportional counter and 7 types of moderator.
The moderators were a spherical shape that was made of polyethylene (PE, 0.95 g/cm3 ) withdiameters of 3 inch, 4 inch, 5 inch, 7 inch, 9.5 inch, and 2 types of polyethylene with inner metalshells. The polyethylene with inner metal shell has 3 layers with 4-inch-diameter PE sphereand 5-inch-diameter inner metal shell (Cu or Pb), and 7-inch-diameter PE shell. The BSS wasplaced at 40 cm (to the detector center) from the top surface of the metal grating using an
aluminum supporting frame.
Output signals from the neutron detectors were fed to a data acquisition system consistingof standard NIM and VME modules. The signals of BSS are passed through a pre-amplifier
and an amplifier. The number of 3 He(n,p)T reactions was recorded from pulse height spectra
for each moderator. On the other hand, data of QDC values of the scintillator, and two vetodetectors were recorded event-by-event.

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JAEA-Conf 2023-001

3Data Analysis - Unfolding method

3.1

Liquid Scintillator

Analysis on the experimental data obtained by the scintillator is basically the same as theprevious study [1]. Only a brief data analysis is described in this section. The data were processed by the following procedures prior to spectrum unfolding: 1) extraction of neutron events
through event selections; 2) calibration of the channel to light output. After these procedures,the light output distributions for the neutron events could be obtained.
Figure 3(a) shows examples of response functions for the scintillator. The response function
was obtained using a SCINFUL-QMD [3], which was modified by Kajimoto et al. [4]. Source
neutrons were isotopically emitted to the surface of the scintillator. The neutron energy region
between 0 and 1 GeV was divided into 200 steps in a linear interval. A tally with the same
shape and size as the scintillator used in the experiment was applied to the calculation. With
the response functions, the neutron energy spectra were derived by unfolding method using an
iterative Bayesian algorithm [5] in the RooUnfold package [6].

(a) Response functions of the scintillator(b) Response functions of the BSS [7]Figure 3: Calculated neutron response functions.

3.2

Bonner Sphere Spectrometer

Figure 3(b) shows the response function of BSS for conditions of bare, five polyethylene
moderators, and two polyethylene with inner metal shell moderators [7]. The response function
was obtained using the MCNP6.2 Monte Carlo code [8] in the energy range from 10−11 to 105
MeV. The JENDL4-HE library was used for the neutron energy range below 150 MeV. Above
150 MeV, the MCNP6.2 default physics model was used in the simulation. The geometry was
identical to the detailed structure of the facility. Neutron energy spectra were obtained fromits response function and initial guesses by using unfolding code, MAXED [9]. Initial guesses ofneutron energy spectra for unfolding were calculated by the PHITS code (ver. 3.28) [2] using
the default nuclear data library and physical model.

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4Result and Discussion

Figure 4: Comparison of experimental results of neutron spectra for same thickness between
different materials of concrete and steel and calculations results.
Figure 4 shows the experimental neutron spectra obtained by the liquid scintillator andthe BSS. The experimental data from the scintillator were obtained from 10 to 400 MeV. The
experimental one from the BSS and calculation results (initial guesses) were obtained in theenergy region from 10−10 to 104 MeV. Statistical uncertainties were only displayed. The spectra
were different for the same thickness of 40-cm-thick between different materials of concrete andsteel. For the BSS, the initial guesses, which are the same as calculation results, overestimate
the unfolded spectra. However, the shape of unfolded spectra for the BSS has a good agreementwith the initial guesses. This means that the initial one is a critical part of the unfolding process
and can affect the shape of the final results.
Figure 5 shows the detailed comparison of experimental results and calculation ones. The
experimental data from the BSS were interpolated into the same energy interval for the liquid
scintillator. The results between the liquid scintillator and the BSS are different within thefactors of 3.5 for concrete and 2.5 for steel in the energy region from 10 to 400 MeV. The
experimental data from the liquid scintillator tend to overestimate the experimental one fromthe BSS for the energy region below 150 MeV. Above 150 MeV, this trend is reserved.

5

Summary

In this study, experimental measurements were conducted on the spectra of neutrons thatpenetrate concrete and steel shields, when a proton beam of 24 GeV/c was incident on a copper
target at the CHARM facility in the East Hall of the CERN Proton Synchrotron. The neutron
spectra were measured to compare results obtained by the liquid scintillator and the BSS. The
neutron spectra were calculated using the PHITS Monte Carlo code with default data libraryand physics model under a detailed structure of the facility. The results between the liquid- 66 66

JAEA-Conf 2023-001

Figure 5: Comparison of experimental results of neutron spectra for the high-energy region
above 10 MeV and its ratio.
scintillator and the BSS are different within the factors of 3.5 for concrete and 2.5 for steel inthe energy region from 10 to 400 MeV.

References[1] E. Lee, et al., Nucl. Instrum. Methods Phys. Res. A, 998, 165189 (2021).
[2] Y. Iwamoto, et al., J. Nucl. Sci. Technol. 59, 665-675 (2022).
[3] D. Satoh, et al., J. Nucl. Sci. Technol. 39, 657-660 (2002).
[4] T. Kajimoto, et al., Nucl. Instrum. Methods Phys. Res. A, 665, 80-89 (2011).
[5] G. D’Agostini, Nucl. Instrum. Methods Phys. Res. A, 362(2-3) 487-498 (1995).
[6] T. Adye, Proceedings of the PHYSTAT 2011 workshop on statistical issues related to discovery claims in search experiments and unfolding, 313-318 (2011).
[7] A. Masuda, et al., Nucl. Inst. Methods Phys. Res. A, 849, 94-101 (2017).
[8] C.J. Werner, et al., LA-UR-18-20808 (2018).
[9] M. Reginatto, et al., Nucl. Inst. Methods Phys. Res. A, 476, 242-246 (2002).

Acknowledgments
The authors would like to thank the participants of this experiment, the CERN Transport
Group, the operation staff of the IRRAD and CHARM facilities, and the accelerator operatorsof the CERN Control Centre for their assistance in the experimental study.

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10. New analytical model for momentum distribution
on the spallation reaction in inverse kinematics
Riku Matsumura†1, 2, Hideaki Otsu1, He Wang3, and Xiaohui Sun4
1

RIKEN Nishina Center for Accelerator-Based Science, Saitama 351-0198, Japan2
Department of Physics, Saitama University, Saitama 338-8570, Japan
3
RIKEN Cluster for Pioneering Research, Saitama 351-0198, Japan
4
School of Science, Huzhou University, Zhejiang 313000, China†
Email: riku@ribf.riken.jp

We proposed a new analytical model that reproduces the momentum distribution of residual nuclei
produced by the secondary beam, such as 90Sr at 104 MeV/u, impinging on a target using an inverse
reaction kinematics. It is expressed in a simpler form than the conventional ones and is found to reproduce
an asymmetric tail that appear at the low momentum side. This will allow us to more precisely evaluate
transmission efficiency of the produced residual nucleus through a dedicated in-flight separator, which isimportant for deriving the production cross sections.

1

Introduction

In general, when measuring reaction cross sections, it is not enough to just measure the yield after
the reaction. The final result is obtained after several corrections, such as the beam transmission and theeffect of the charge fluctuations when the beam passes through the detectors, and so on. As the beamtransmission, i.e., the momentum/angular acceptance of the spectrometer, is evaluated, the momentum
distribution on the dispersive focal plane becomes important. The shape of the longitudinal momentum
distribution is known to be asymmetric during projectile fragmentation reaction at the lower incident
energy as shown in Fig. 1.

TOF-Bρ-ΔE
Measurement
Objective nuclei

p [MeV/c]Distortion

p [MeV/c]

Figure 1: Schematic illustration of the spallation reaction and the associated distorted momentum distribution using the inverse kinematics method.
Reference [1] theoretically considers that the tail on the low momentum side is due to the momentum
shift of the outgoing two nucleons inside an attractive potential caused by the residual nucleus. And
the cutoff on the high momentum side is due to the phase volume effect reflecting the energy and- 68 68

JAEA-Conf 2023-001

momentum conservation. One of the models to reproduce such a momentum distribution is the Goldhaberequation [2]. The width of the momentum distribution σ is defined byσ = σ0K(A − K)
,
A−1

(1)

where A is the mass number of the projectile, K is the mass number of the spallation-reaction product,and σ0 is known to be about 90 MeV/c. Refs. [3, 4] states that while the high momentum side is mostly
reproduced in Eq. (1), the tail on the low momentum side is a problem.
Therefore, Tarazov [5] introduced the following asymmetric coefficient,
α=

σhigh
σlow
−1=1−
,
σ
σ

(2)

which reproduces the different widths of the left and right sides of the momentum distribution. In
LISE++ [6], the σ given by the model in Refs. [2, 7, 8] is used. Note that this value has been exper-imentally
verified to be acceptable up to 30% according to Ref. [4]. However, it is difficult to understand why thedivision into cases is required to reproduce a single physical quantity. Thus, we attempted to devise a new
analytical model.

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2

Experiment

The series of experiments [9–12] were performed at the RIKEN Radioactive Isotope Beam Factory(RIBF) by using the RIKEN Projectile-fragment Separator (BigRIPS) [13] and the ZeroDegree Spectrometer (ZDS) [13]. An experimental setup is shown in Figure 2. The details of the experiment are
given in Ref. [10]. The secondary beam, including 90 Sr, was produced by in-flight fission of 238 U at
345 MeV/nucleon on a 3-mm thick 9 Be production target at the BigRIPS first stage. In the following second stage, the beam particles were selected and identified event-by-event using the TOF-Bρ-∆E
method [14].

Figure 2: Schematic view of the RIKEN Projectile-fragment Separator (BigRIPS) and the ZeroDegree
Spectrometer (ZDS).
The beam particles bombarded at 104 MeV/nucleon to CH2 (179.2 mg/cm2 ), CD2 (218.2 mg/cm2 ),and C (226.0 mg/cm2 ) reaction targets, which placed at the entrance of the ZDS. The residual nuclei
produced in reactions were identified in the ZDS with the same method as the BigRIPS. Because themomentum acceptance of the ZDS is limited to ±3 %, the experiment was carried out by using fivedifferent momentum settings (∆ (Bρ) /Bρ = −9, −6, −3, 0, and +3 %) for each target to accept thewide range of mass-to-charge ratio A/Q. Figure 3 shows an example of particle identifications after
selecting 90 Sr (Z = 38, A/Q = 2.37) for the projectile and the ∆ (Bρ) /Bρ = −6 % setting at the ZDS.
The production cross sections for each isotopes were deduced from the number of each residual nuclei
normalized by the number of incident secondary 90 Sr particles using the thickness of the targets. The
backgrounds of carbon from CH2 and CD2 targets and beam-line materials were subtracted by using theempty and carbon target runs. Figure 3 right shows that momentum distributions (solid curves) using
Eq. (1, 2) with parameters optimized for 86 Sr. This expression, however, can not reproduce the data forother residual nuclei. Thus, we need to create a new expression to describe momentum distribution witha simple formula.

Figure 3: Left) Residual particle identifications at the ZDS. Right) Measured momentum distributions
are compared with calculated ones when optimized for the 86 Sr spectrum.

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3

New analytical model

In order to reproduce the momentum distribution of 104 MeV/u incident energy data, the newly
devised model function is introduced as:σ(p) = σ0 + α (p − µ) ,(3)

where α is a newly introduced parameter. Thischanges the σ of the Gaussian and produces asymmetry. The function is intuitive and easy to understand.

Behavior of the model
Figure 4 shows a momentum distribution after
the reaction with the CH2 target and the blue dotline are the fitting results using Eq. (3). It seems to
reproduce the asymmetry well for all nuclides. Theα obtained from fitting ranged from 0.056 to 0.093.

Asymmetric parameter α′

0.14

Y

Sr

Rb

0.12
0.1
0.08
0.06
0.04
0.02
81

82

83

84
85
86
Mass number A

87

88

89

Figure 5: Asymmetric parameter α obtained fromthe fitting shown in Fig. 4 plotted against mass
number A.
This is actually one value that appears to havethe possibility of being reproduced. Although there
is some fluctuation for each nuclide, we obtainedα = 0.0738 ± 0.0057 using a weighted average. The
result is overlaid on the red line in Fig. 4. Theα value is obtained from the data of CH2 target,
thus the parameter includes the effects of interaction both with carbon and hydrogen. Still, using
the data of pure carbon target, we can extract theα value for hydrogen target. Similarly, α value for
Figure 4: Momentum distributions calculated bydeuteron can be obtained. In addition, we would
Eq. (3) with α = 0.0738 for residual nuclei withlike to discuss whether this asymmetry is due to
Z = Zproj (38) ± 1.
the reaction or simply to the energy loss, based on
experimental data.

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Advanced approach
Even for particles that are somewhat cutoff by the momentum acceptance of the spectrometer, thecentral and sigma value of momentum can be inferred from other nuclides with full acceptance becauseof its linearity, and the yield can be reproduced to a certain extent. If only the rise on one side could
be determined, the original momentum distribution might be reproduced. This is measured with fivepatterns of magnetic field settings as described in Chap. 2, which leads to a reduction of statistical errors
for particles in overlapping regions.

Figure 6: Left) As can be seen from Fig. 3 right, 87 Sr deviates slightly from the momentum acceptance,
but the model function introduced this time can reproduce the original statistics. Right) The verticalaxis is the production ratio, normalized by the number of incident 90 Sr beam.
We have counted its yield in the ∆ (Bρ) /Bρ = −3 % setting, where 87 Sr is definitely within the momentum acceptance, but by using this method, the yield in the ∆ (Bρ) /Bρ = −6 % setting is found to agree
within the error.

4

Conclusion

We devised a new analytical model to reproduce the momentum distribution. In spite of the simplicityof the function, in contrast to the conventional method, the proposed expression can well reproduce the
distribution with higher accuracy. The value of α is almost constant within the error, and the introductionof one value is sufficient to reproduce the momentum distribution of the isotope in this incident energy
region. Note that this value may only be dominant for C within CH2 , so we are considering a method to
extract the momentum component of only H by some method such as subtraction. In the future, we plan
to analyze the energy dependence of α at other energies, as it may be an important physical quantity
involved in the reaction.

Acknowledgments
238

We are grateful to the accelerator staff of the RIKEN Nishina Center for providing a high-quality
U beam. This work was supported by RIKEN Junior Research Associate Program.

References[1] K. Ogata et al., “Asymmetry of the parallel momentum distribution of (p, pN) reaction residues”,
Phys. Rev. C 92, 034616 (2015).
[2] A.S. Goldhaber, “Statistical models of fragmentation processes”, Phys. Lett. B 53, 306 (1974).
[3] M. Notani et al., “Projectile fragmentation reactions and production of nuclei near the neutron
drip-line”, Phys. Rev. C 76, 044605 (2007).

- 72 72

JAEA-Conf 2023-001[4] S. Momota et al., “Momentum peak shift and width of longitudinal momentum distribution ofprojectilelike fragments produced at E = 290 MeV/nucleon”, Phys. Rev. C 97, 044604 (2018).
[5] O.B. Tarasov, “Analysis of momentum distributions of projectile fragmentation products”, Nucl.
Phys. A 734, 536 (2004).
[6] O.B. Tarasov et al., “LISE++: Radioactive beam production with in-flight separators”, Nucl. Instrum. Meth. B 266, 4657 (2008).
[7] D.J. Morrissey, “Systematics of momentum distributions from reactions with relativistic ions”, Phys.
Rev. C 39, 460 (1989).
[8] W.A. Friedman, “Heavy ion projectile fragmentation: A reexamination”, Phys. Rev. C 27, 569(1983).
[9] H. Wang et al., “Spallation reaction study for fission products in nuclear waste: Cross section
measurements for 137 Cs and 90 Sr on proton and deuteron”, Phys. Lett. B 754, 104 (2016).
[10] S. Kawase et al., “Study of proton and deuteron induced spallation reactions on the long-lived fission
product 93 Zr at 105 MeV/nucleon in inverse kinematics”, Prog. Theor. Exp. Phys. 2017, 093D03(2017).
[11] K. Nakano et al., “Isotope production in proton-, deuteron-, and carbon-induced reactions on 93 Nb
at 113 MeV/nucleon”, Phys. Rev. C 100, 044605 (2019).
[12] X.H. Sun et al., “Spallation and fragmentation cross sections for 168 MeV/nucleon 136 Xe ions on
proton, deuteron, and carbon targets”, Phys. Rev. C 101, 064623 (2020).
[13] T. Kubo et al., “BigRIPS separator and ZeroDegree spectrometer at RIKEN RI Beam Factory”,
Prog. Theor. Exp. Phys. 2012, 03C003 (2012).
[14] N. Fukuda et al., “Identification and separation of radioactive isotope beams by the BigRIPS separator at the RIKEN RI Beam Factory”, Nucl. Instrum. Meth. B 317, 323 (2013).

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JAEA-Conf 2023-001

11. Neutron Capture Cross Section Measurement of
129
I and 127I using ANNRI at MLF/J-PARC
Gerard ROVIRA†1 , Atsushi KIMURA1 , Shoji NAKAMURA1 , Shunsuke ENDO1 ,Osamu IWAMOTO1 , Nobuyuki IWAMOTO1 , Yosuke TOH1 , Mariko SEGAWA1 ,Makoto MAEDA1 , and Tatsuya KATABUCHI2
1

Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki, Japan
2
Laboratory for Zero-Carbon Energy, Tokyo Institute of Technology, Tokyo, Japan†
Email: gerard.rovira@jaea.go.jp

Abstract
Neutron capture cross section measurements for 129 I and 127 I have been conducted at the
Accurate Neutron-Nucleus Reaction measurement Instrument (ANNRI) of the Materials andLife science Facility (MLF) in the Japan Proton Accelerator Research Complex (J-PARC).
Neutron time-of-flight experiments were performed to determine the cross sections of 129 I
from 10 eV to 1 keV and of 127 I from 0.01 eV to 1 keV. For 127 I, the present preliminary
results agree within uncertainties with JENDL-5. In the case of 129 I, 16 s-wave resonances
could be confirmed and their cross sections were found to be comparable with those of
JENDL-5.

1

Introduction

Reducing the long-term accumulation of high-level nuclear waste (HLW), mainly constituted byminor actinides (MAs) and long-lived fission products (LLFPs), is one of the most important
challenges regarding the management of nuclear waste. To achieve this goal, nuclear transmutation has been proposed to convert the HLW into short-lived nuclei. While the main focus is on
the development of Accelerator-Driven Systems (ADS), a transmutation facility for MAs, several
solutions have been proposed for LLFPs involving the use of nuclear reactors [1, 2]. For LLFPs,
nuclear transmutation can only be achieved through the neutron capture reaction, meaning thatan accurate characterization of the neutron capture cross section is of the utmost importance.
Moreover, for the majority of LLFPs such as 129 I, 126 Sn, 93 Zr and 79 Se, in most of the neutronenergy region between thermal to keV energies, neutron capture cross sections have scarcely
been measured. Hence, to accurately predict nuclear characteristics in transmutation reactors
for LLFPs, further experiments are required to extend the present knowledge of the capture
reaction of LLFPs from the thermal to keV neutron energies.
Iodine-129, a LLFP with a 15.7 million years half-life, is one of the targets for transmutation
due to the fact that it is soluble and has low absorption to underground materials, which causes
problems in long-term geological disposals compared to other LLFPs [2]. Being soluble also
makes the handling of 129 I complicated, which is one of the main reasons why the experimental
data for the neutron capture cross section of 129 I is so scarce. Only two experimental data setsusing the time-of-flight (TOF) method are available, those of Noguere et al. [3] and Macklin [4],which cover the neutron energy range from about 1.6 and 72 eV, respectively. These data are- 74 74

JAEA-Conf 2023-001

complemented by several other experimental data at the thermal energy using the activation
method [5, 6, 7, 8, 9].
In the present work, preliminary results of the neutron capture cross section of 129I from 10
eV to 1 keV measured at the Accurate Neutron-Nucleus Reaction measurement Instrument (ANNRI)of the Materials and Life science experimental Facility (MLF) in the Japan Proton Accelerator
Research Complex (J-PARC) are presented. Moreover, since the 129I sample con-tained about
15.4% in mass concentration of 127I, the neutron capture cross section of 127I was also measured
using a separate sample with 100% abundance of 127I and preliminary results are also included.

2

Experimental Setup

The experiments were performed at the ANNRI beamline of the MLF facility in J-PARC. Pulsed
neutrons were generated by the Japanese Spallation Neutron Source (JSNS) in MLF using the 3 GeV
protons of the J-PARC facility, in which the protons were shot in double-bunch mode every 40 ms andwith a beam power of about 700 kW at the time of the experiment. In the experiments, prompt capture
γ-rays were detected using a NaI(Tl) detector installed in the experimental area 2 of the ANNRI
beamline. The NaI(Tl) detector was situated at a 90◦ angle with respect to the neutron beam axis and aneutron ﬂight path of 27.9 m. Further information about the time-of-ﬂight experimental setup can befound elsewhere [12].
The 129I sample employed in this experiment amounted to 404(1) mg in mass, with a 20 mm
diameter and a 4.1 mm thickness. This sample contained 129I with an isotopic abundance of 84.6%
alongside 15.4% of 127I, in the form of sodium iodide (NaI) and encapsulated in a Ti case with a 30 min
diameter and 0.4 mm-thick walls. A thorough sample analysis performed by Segawa et al. [11]determined that the sample had been damaged and contained an empty space amounting toapproximately 17%. Hence, in the present experiment, to avoid irradiating the empty space in thesample, the smaller neutron collimator of 7 mm in diameter was employed. A dummy sample replica of
the Ti case was used to derive the sample-dependent background induced by the Ti case. However, thedummy sample contained the same amount of NaI to that in the 129I sample but with a 100% isotopic
concentration of 127I, meaning that the dummy sample contained 6.5 times more 127I compared to the
129I sample. Moreover, to measure the neutron capture cross section of 127I and, at the same time, toaccurately determine the eﬀects of 127I in both the 129I and dummy samples, an 127I sample with a massof 562.7(1) mg with a 100% isotopic abundance of 127I was also measured in the present experiments.
The incident neutron ﬂux was derived with a boron sample enriched with 10B up to 90% with a diameterof 10 mm and a thickness of 0.5 mm. The 10B(n, α)7Li reaction emits a lone γ-ray with the energy of478 keV, making events from this reaction easy to isolate. An 197Au sample with a mass of 609.7(1)mg, a diameter of 20 mm and a thickness of 0.1 mm was employed to normalize the neutron capture
cross section results using the saturated resonance technique. Finally, the sample-dependent
backgrounds due to scattered neutrons for the 129I, 127I, boron and 197Au samples were determined byusing a carbon sample.

3

Data Analysis

The experimental results were analyzed oﬄine by means of the pulse-height weighting technique(PHWT) [10]. The 129I and 127I neutron capture yields were derived by applying the PHWT and aweighting function that takes into account the sample characteristics and detector eﬃciencies. In thepresent work, the weighting functions for the 129I and 127I samples were obtained with Monte-Carlosimulations with the SG code [13].

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JAEA-Conf 2023-001

3.1

Neutron Flux

The shape of the incident neutron flux was derived by gating the 478 keV γ-rays emitted fromthe 10 B(n, α)7 Li reaction measured with the boron sample, after removing the energy-dependent
influence of the 10 B(n, α)7 Li reaction rate using the Monte-Carlo code PHITS [14]. The incident
neutron flux from 10 meV to 1 keV determined in the present experiment is shown in Fig. 1.
Neutron Flux [n/proton shot/eV/100 ns]

8

10

Boron

107
6

10

5

10

4

10

3

10

2

10

1

10

0

10

10-2

10-1
100
101
102
Neutron energy [eV]103

Figure 1: Incident neutron flux from 10 meV to 1 keV.

3.2

Background Subtraction

In order to accurately isolate the quantities of interest in the present experiment, namely thethe neutron capture yields of the 129 I and 127 I samples, several layers of detrimental backgroundand noise had to be removed.
For the case of the 127 I sample, the background was constituted by the sample-dependent
background, mainly caused by neutrons being scattered at the 127 I sample, and the sampleindependent background. As mentioned in section 2, the carbon sample was employed to estimate the contribution of the events caused by neutrons scattered at the measured samples.
This is a commonly used technique since the neutron elastic scattering is the dominant reaction in carbon and has a flat energy-dependence up to 500 keV. Hence, the neutron capture
yield of the 127 I sample was obtained by removing the sample-dependent background, using thecarbon sample measurement and taking into account the relative differences in both mass andcross section between 127 I and carbon, and the sample-independent background with a ”blank”
measurement in the no-sample condition.
For the 129 I sample, however, the situation was much more complicated. Since the amount127
ofI in the 129 I sample was not equal to that in the dummy sample, the dummy sample could
not be directly employed to remove the influence of the Ti case. Thus, the neutron capture yieldof 127 I sample was utilized to remove the influence of the 127 I neutron capture events measured
with the dummy sample and isolate the influence of the Ti case. This removal was performed
together with corrections using the PHITS code to account for the influence of the Ti case that
increased the neutron capture yield of 127 I in the resonance region, as can be clearly seen in Fig.
2. The events induced by the Ti case were then removed in the 129 I sample measurement using
the dummy sample measurements, after removing the neutron capture yield of the 127 I sample.
Moreover, the influence of 127 I, which was contained in the 129 I sample with a 15.4% isotopic
abundance, was also removed using the neutron capture yield of the 127 I sample. Finally, in a

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JAEA-Conf 2023-001

procedure analogous to the analysis of the 127 I sample, the sample-dependent background due
to neutron scattered at the 129 I sample and the sample-independent background were removed
using the carbon sample measurement and a no-sample measurement, respectively.

Figure 2: Simulated neutron capture yield ratio between the dummy and the 127 I samples in
the TOF range between 100 µs and 10 ms, which is from 40 meV to 400 eV in neutron energy.

3.3

Cross Section Calculation

Preliminary results for the neutron capture cross section of 129 I and 127 I were determined by
dividing the neutron capture yields, which were corrected from the self-shielding and multiple
scattering effects using the PHITS code, by the incident neutron flux.
For both samples, the results were normalized using the saturate resonance technique withthe 197 Au sample. The thickness of the 197 Au sample was 0.1 mm, enough for the first resonanceto be completely saturated. By means of this technique, the neutron capture cross sections were
determined as follows:
σI (En ) = Nsat

YI (En )CI (En )φn (En )SI(1)

where σI (En ), YI (En ), CI (En ), SI and Nsat stand for the neutron capture cross section, neutron
capture yield, the correction factor for self-shielding and multiple scattering, the area density,and the normalization factor, for either 129 I or 127 I, with φn (En ) as the incident neutron flux.
Moreover, for 129 I, the area density was corrected using the results found in a thorough analysis
by Segawa et al. [11]4Preliminary Results

Preliminary results for the neutron capture cross sections of 129 I and 127 I were determined using
the formulations explained in section 3.3. The neutron capture cross section of 127 I comparedto the broadened data of JENDL-5 [15] are shown in Fig. 3. As can be seen, the present results
agree within uncertainties with the results from JENDL-5.

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Cross Section [b]JAEA-Conf 2023-001

10

4

10

3

10

2

10

1

10

0

Present
JENDL-5 Broadened-11010-2 -2
10

-1

10

0

1

10
10
Neutron energy [eV]

2

10

10

3

Figure 3: Preliminary results for the 127 I neutron capture cross section from 0.01 eV to 1 keVcompared to the broadened data of JENDL-5.
For 129 I, the preliminary results are displayed in Fig. 4 in comparison to the data fromJENDL-5. In the energy region between 10 eV and 1 keV, 16 s-wave resonances could be
identified. Since most of the resonances for 129 I occur above 100 eV, these resonance appeared
in a doublet structure due to the influence of the double-bunch mode. Nonetheless, the present
data was found to be comparable with the cross section data of JENDL-5 once corrected withthe resolution function of the ANNRI beamline. The resonance parameters of JENDL-5, except
for those of negative resonances, were taken from the work of Noguere et al. [3], in which theresonance parameters were determined from a combined analysis of neutron capture yields andtransmission data measured at the GELINA facility. Such consistency of cross sections between
the present experiments and JENDL-5 indicates that the present data are reasonable with thedata of Noguere et al., in spite of performing complicated subtractions of components of 127 I
and Ti case from the yield data of the 129 I sample. Unfortunately, small resonances in JENDL-5
could not be confirmed due to a high background level around 5 b.
1000

Present
JENDL-5 Broadened

Cross Section [b]

100
10
1
0.1
0.01
10

100
Neutron energy [keV]

1000

Figure 4: Preliminary results for the 129 I neutron capture cross section from 10 eV to 1 keVcompared to the broadened data of JENDL-5.

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JAEA-Conf 2023-001

5

Summary

The neutron capture cross sections of 129I and 127I were measured at the ANNRI beamline of MLF in JPARC from 10 eV to 1 keV and from 0.01 eV to 1 keV, respectively. For 127I, the present preliminary
results provide agreement within uncertainties with the data in JENDL-5. In the case of 129I, in thepresent preliminary results 16 s-wave resonance could be identiﬁed that are comparable with those of
JENDL-5. The present data are expected to be consistent with the data of Noguere et al., performed at
the GELINA experimental facility.

References[1] Chiba S, Wakabashi T, Yoshiaki T, et al. Method to Reduce Long-lived Fission Products by
Nuclear Transmutations with Fast Spectrum Reactors. Sci. Rep., 2017; 7:13961.
[2] Wakabayashi T, Tachi Y, Takahashi M, et al. Study on method to achieve high transmu-tationof LLFP using fast reactor. Sci. Rep., 2019; 9:2-12.
[3] Noguere G, Bouland O, Brusegan A, et al. Neutron capture and total cross sections of 127I and
129I. Phy. Rev. C, 2006; 74:054602.
[4] Macklin RL. Neutron Capture Cross Sections and Resonances of Iodine-127 and Iodine-129.
Nucl. Sci. Eng., 1983; 85:350.
[5] Roy J and Wuschke D. Neutron Capture Cross Section of I-129 and I-130. Can. J. Chem.,
1958; 36:1424-1430.
[6] Pattenden NJ. Neutron Cross Section Measurements on Fission Product Samarium and
Iodine. Nucl. Sci. Eng., 1963; 17:371-380.
[7] Friedmann L and Aumann DC. The Thermal Neutron Cross-Sections and Resonance Inte-gralsof 127I, 128I and 129I. Radiochimica Acta, 1983; 33:183-187.
[8] Nakamura S, Harada H, Katoh T, and Ogata Y. Measurement of Thermal Neutron Capture Cross
Section and Resonance Integral of the 129I(n,γ)130I Reaction. J. Nucl. Sci. Technol., 1996;
33:283-289.
[9] Belgya T, Bouland O, Noguere G, Plompen A, Schillebeeckx P and Szentmiklósi L. The
thermal neutron capture cross section of 129I. Proceedings of the international conference on
nuclear data for science and technology, Nice 2007; 631.
[10] Moxon MC et al., A gamma-ray detector for neutron capture cross-section measurements. Nucl.
Inst. and Meth., 1963. 24:445-455.
[11] Segawa M, Toh Y, Kai T, et al., Investigation of radioactive samples for neutron capture
reaction measurements using energy-resolved neutron imaging, Ann. Nucl. Energ., 2022;
167:108828.
[12] Rovira G et al., Neutron capture cross-section measurement and resolved resonance analysis of
237Np, J. Nucl. Sci. Technol. 2020; 57:24-39.
[13] Ohsaki T et al., An NaI(Tl) spectrometer system for keV neutron radiative-capture reac-tions.
Nuc. Ins. and Meth. in Phys., A 1999; 425:302-319[14] Sato T. et al., Features of Particle and Heavy Ion Transport Code System PHITS Version 3.02,
J. Nucl. Sci. Technol. 2018; 55:684-690.
[15] Iwamoto O, Iwamoto N, Kunieda S, et al., Japanese evaluated nuclear data library version 5:
JENDL-5, J. Nucl. Sci. Technol., 2023; 60:1-60.

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JAEA-Conf 2023-001

12. Measurement of heavy nuclide production
cross-section for natPb irradiated with several GeV
protons
Kenta SUGIHARA†∗1 , Shin-ichiro MEIGO1 , Hiroki IWAMOTO1,2 , and Fujio
MAEKAWA1
1
2

J-PARC Center, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai-mura, Naka-gun,Ibaraki Pref. 319-1195, Japan

Nuclear Science and Engineering Center, Japan Atomic Energy Agency, 2-4 Shirakata,
Tokai-mura, Naka-gun, Ibaraki Pref. 319-1195, Japan†

Email: kenta.sugihara@kek.jp

Abstract
Nuclide production cross sections are fundamental to estimate the γ-ray dose rate. Thus,
we started the cross section measurement via the reactions of GeV proton incidence onvarious targets. This paper presents the measured cross sections via the nat Pb(p,X) reactions.
Comparisons among present data, calculated results, and evaluated nuclear data library arealso reported.

1

Introduction

These days, various applications with neutrons are paid much attention, e.g., boron neutron capture therapy[1, 2] and accelerator-driven neutron source[3, 4, 5, 6]. Accelerator-Driven
System (ADS)[7, 8, 9, 10] for the transmutation of nuclear waste is one example of such applications. In the design of the ADS facility, it is of great importance to ensure safety for radiation
workers and neighbors. Thus, precise evaluation of the residual γ-ray dose rate by the reactions
among primary protons, target of neutron production (Pb-Bi eutectic), the beam window, andaccelerator components is required. The nuclide production cross section is key information
to estimate the γ-ray dose rate. These days, nuclear reaction models such as Liège IntraNuclear Cascade (INCL)[11] followed by Generalized Evaporation Model (GEM)[12] in Particle
and Heavy Ion Transport code System (PHITS)[13] and evaluated nuclear data libraries such
as Japanese Evaluated Nuclear Data Library High Energy file 2007 (JENDL/HE-2007)[14] areutilized to derive the γ-ray dose rate. However, the prediction accuracy of the models should
be confirmed in advance because the applicability of the models is not completely understood.
There are references for the cross sections via the nat Pb(p,X) reaction with GeV proton incidence[15, 16]. In previous studies, monitor reactions were utilized to determine the intensityof the incident protons. Because the increase of uncertainty due to the monitor reactions wasinevitable in previous studies, more precise measured data are desired currently.
∗

Present address: High Energy Accelerator Organization (KEK), Oho, Tsukuba, Ibaraki 305-0801, Japan and
The Graduate University for Advanced Studies (SOKENDAI), Hayama, Kanagawa 240-0193, Japan- 80 80

JAEA-Conf 2023-001

Then, we started a series of experiments at Japan Proton Accelerator Research Complex (JPARC)[17, 18], where a high-precision current transformer with 2% uncertainty is equipped. In
the past, the cross section with smaller uncertainties was successfully obtained using several GeV
protons and Al, Ni, Zr, Mn, and Co[19, 20, 21] at J-PARC by means of the activation technique.
Here, we measured the nuclide production cross sections with GeV protons and nat Pb which isused as the target of neutron production. This paper presents the heavy nuclide production
cross sections via the nat Pb(p,X) reaction. In addition, present data MR
were compared with theresults by nuclear reaction models and JENDL/HE-2007 to confirm the prediction accuracy.
Our Exp.
1,

2

Experiment

MLF

RCS

Our experiment was carried out at a beam
dump line[22, 23] near the extraction port
Proton beam direction
from the 3 GeV Rapid Cycling Synchrotron(RCS)[22] at J-PARC. The vertical plane viewis illustrated in Fig. 1. The experimental proChambercedure, such as sample setting, proton beam
Beam dump
irradiation, and γ-ray measurement of theactivated samples, were followed in previous Figure 1: Vertical plane view of the beam dump
studies[19, 20, 21]. Due to the limited space, line at J-PARC.
a procedure is explained briefly.
The proton beam was supplied from the RCS to nat Pb sample as shown in Fig. 1. The protonenergies were 0.4, 1.3, 1.5, 2.2, and 3.0 GeV. For 0.4-, 1.5-, 3.0-GeV protons, the irradiation time
and the incident particle number were applied to 75 seconds and 8.6 × 1013 , respectively. Those
for 1.3- and 2.2-GeV protons were 100 seconds and 1.1 × 1014 , respectively.
The nat Pb targets were inserted in theplace of “The chamber” in Fig. 1. The tar3 GeV p +Pb
get foil, Al, Ce, Pb, and Al in order from upPb
Dy
331.17 keV
226.92 keV
10stream, were used for 0.4-, 1.5-, 3.0-GeV protons. For the case of 1.3- and 2.2-GeV protons,
Hg
the Al, Si, Pb, and Al foil were applied. For
279.2 keVboth experiments, the size and weight of theRe
10
Cs
360.7 keV
411.95 keV
Pb target was 25 mm × 25 mm × 0.22 mm
10Energy [keV]and 1.4 g, respectively.
After the proton irradiation, the γ-ray
spectra were obtained with High-Purity Ge Figure 2: γ-ray spectra by the HPGe detector.
(HPGe) detectors. The measured γ-ray spec- The horizontal and vertical axes are γ-ray entrum for 3 GeV proton incidence on nat Pb is ergy [keV] and pulse height of each γ-ray energy
shown in Fig. 2. A variety of peaks were ob- [-], respectively.
served in Fig. 2.
10nat

Pulse Height [-]

201

155

4

192

3

181

127

2

4

3

Results and Discussion

We let references[19, 20, 21] explain the way of data analysis due to the limited space.
Heavy nuclides production cross sections obtained in this work are tabulated in Table 1. The
statistical error, ambiguity of fitting parameter, projectile proton number, branching ratio of the
γ-ray energy used in our analysis, and intensity of the standard γ-ray sources were taken into
account as the total uncertainty of present data. In this study, we measured 49 cross sectionsof 12 nuclides and 5 proton energy points. For 192 Hg by 0.4-, 1.3-, 3.0-GeV proton incidence,- 81 81JAEA-Conf 2023-001

202m Pb by 3.0-GeV proton incidence, and 203 Bi by 1.3-GeV proton incidence cross sections, theuncertainty about 9%, 13%, and 15%, respectively, are greater than that of the previous resultsby Yu. E. Titarenko et al.[15]. Therefore, we successfully acquired about 90% of the data withsmaller uncertainty compared with preceding studies.
Table 1: Nuclide production cross sections of the reactions for nat Pb with 0.4-, 1.3-, 1.5-, 2.2-,
and 3.0-GeV protons. Type “i” and “c” represent independent and cumulative cross sections,
respectively. The branching ratio of used γ-ray energy (Eγ ) is denoted in the parenthesis below
each Eγ . The total uncertainty (1σ) is written in the parenthesis below each cross section.
Cross section (1σ Uncertainty) [mb]Eγ
T1/2
NuclideType[keV]
0.4 GeV 1.3 GeV 1.5 GeV 2.2 GeV 3.0 GeV
206 Bi803.1
c6.243 d
6.20
3.18
3.00
3.44
(99.0%)(0.22)(0.11)(0.11)(0.14)
205 Bi1043.75c
14.91 d
9.79
4.44
3.71
4.15
3.83
(7.51%)(0.37)(0.19)(0.14)(0.32)(0.51)
203 Bi820.2
c11.76 h
13.24
5.60
4.28
3.90
(29.7%)(0.94)(0.84)(0.23)(0.29)
203 Pb279.2
c51.92 h
55.87
32.48
31.78
19.08
(80.94%)(1.89)(1.51)(1.35)(1.18)
202m Pb
786.99i
3.54 h
17.74
12.45
10.84
9.59
8.73
(49%)
(1.23)(0.92)(0.84)(2.06)(1.12)
201 Pb331.17c9.33 h
55.59
24.27
22.87
14.26
(77%)
(4.69)(2.05)(1.94)(1.37)
200 Pb147.63c21.5 h53.14
20.12(38.2%)(3.21)(0.98)
202 Tl439.51c
12.31 d
23.57
16.96
16.80
18.73
13.09
(91.5%)(0.85)(0.58)(0.59)(0.84)(0.88)
201 Tl167.43c
3.0421 d
81.55
43.45
43.98
(10.0%)(2.95)(1.59)(1.52)
203 Hg279.2
c46.610 d
2.47
3.58
3.44
3.40
2.91
(81.56%)(0.08)(0.12)(0.15)(0.27)(0.09)
192 Hg274.8
c4.85 h
54.60
23.98
22.21
10.30
(52%)
(4.56)(2.02)(1.86)(1.16)
196 Au355.73i
6.1669 d
2.93
3.22
3.18
2.04
(87%)
(0.14)(0.15)(0.153)(0.15)
Figure 3 shows the excitation functions of 206 Bi, 203 Pb, 201 Pb, 202 Tl, 203 Hg, and 196 Au with
INCL/GEM, JENDL/HE-2007, and preceding studies[15, 16, 24, 25, 26]. For overall trends,
most of present data is consistent with the preceding results. For 206 Bi production, INCL/GEM
shows better agreement with present data than JENDL/HE-2007. The average ratio of calculation to experiment (C/E) is 1.01. On the other hand, JENDL/HE-2007 shows an overestimationof the present data by 28% in average.
The chart for average C/E values between INCL/GEM and the present data is shown in
Fig. 4. According to Fig. 4, better reproducibility or underestimation by roughly to be 30%
is clearly seen for the production of Bi and Pb nuclides. On the contrary, overestimation byapproximately twice is confirmed for Tl and Au nuclides production cross sections except for
201 Tl. INCL/GEM might have weakness in describing the reactions of several proton emissions
compared with those of less than one proton emission. However, it should be noted that further
investigation is required to acquire this evidence.

- 82 82

JAEA-Conf 2023-001

This work

natPb(p,X)206Bi

INCL/GEM

Cross Section [mb]Cross Section [mb]cumulative

10
This work
INCL/GEMJENDL/HE-2007
M.Gloris+(2001)

JENDL/HE-2007
Y.Q.Ju+(2015)
M.Gloris+(2001)

102

Yu.E.Titarenko+(2009)

natPb(p,X)203Pb

M.Gloris+(1996)1
10−1

cumulative

Yu.E.Titarenko+(2009)10

1
Proton Energy [GeV]

10-1

4

natPb(p,X)202Tl

This work

H.Yashima+(2004)

10

10

Cross Section [mb]Cross Section [mb]Y.Q.Ju+(2015)
Yu.E.Titarenko+(2009)

natPb(p,X)201Pb
cumulative

10-1

1
Proton Energy [GeV]1
Proton Energy [GeV]This work

natPb(p,X)203Hg

This work

INCL/GEM

cumulative

INCL/GEM

Y.Q.Ju+(2015)

1
10-1

10-1

6

JENDL/HE-2007

10

102

10

Cross Section [mb]Cross Section [mb]JENDL/HE-2007

M.Gloris+(2001)
Yu.E.Titarenko+(2009)1
Proton Energy [GeV]

7

natPb(p,X)196Au
independent

JENDL/HE-2007
Y.Q.Ju+(2015)

10

1
10-1
8

5

This work
INCL/GEMJENDL/HE-2007
Y.Q.Ju+(2015)
M.Gloris+(2001)
M.Gloris+(1996)
H.Yashima+(2004)
Yu.E.Titarenko+(2009)

cumulative

INCL/GEM

2

1
Proton Energy [GeV]

Yu.E.Titarenko+(2009)1
Proton Energy [GeV]

9

Figure 3: Excitation functions of 206 Bi, 203 Pb, 201 Pb, 202 Tl, 203 Hg, and 196 Au with INCL/GEM,
JENDL/HE-2007, and previous results which are taken from EXFOR. The horizontal and vertical axes of all of the graphs represent the proton energy [GeV] and the nuclide production crosssection [mb], respectively. The red and black markers stand for present data and preceding
results, respectively. The blue and pink lines mean the results of INCL/GEM and JENDL/HE2007, respectively.

- 83 83

JAEA-Conf 2023-001

INCL/GEMとExp.の比較: natPb(追加分あり)
202Bi
1.7 h

203Bi
11.8 hC/E=0.70

204Bi
11.2 h200
Pb
21.5 hC/E=0.72

201
Pb
9.3 h
C/E=0.68

202
Pb
5.2e4 y203
Pb51.9 hC/E=0.84

198
Tl
5.3 h

199
Tl
7.4 h

200
Tl
26.1 h

201
Tl
3.0 d
C/E=0.73

196
Hgstable197
Hg64.1 h198
Hgstable199
Hgstable195
Au
186.0 d

196
Au
6.2 d
C/E=1.5

197
Austable

198

Au
2.7 d

206Bi
6.2 d
C/E=1.01

207Bi
31.6 y208Bi
3.7e5 y209Bi
2.0e19 y

Pb
1.4%

205
Pb
1.7e7 y

206
Pb
24.1%

207
Pb
22.1%

208
Pb
52.4%

202
Tl
12.2 dC/E=2.3

203Tlstable

204
Tl
3.8 y

205
Tl
stable

206
Tl
4.2 m

207
Tl
4.8 m

200
Hg
stable201
Hgstable202
Hgstable203Hg46.6 dC/E=1.8

204
Hgstable

205

199

200
Au
48.4 m201
Au
26.0 m202
Au
28.4 s

Au
3.1 d

205Bi
14.9 dC/E=0.94

204

210Bi
5.0 d

209

Pb
3.2 h

Hg
5.1 m

203

Au
60 s

Figure 4: Chart for average C/E values between INCL/GEM and the present data. Red-,
green-, and blue-filled boxes represent overestimation, better accuracy, and underestimation,
respectively.

4

2

Conclusion

We measured heavy nuclides production cross sections via the nat Pb(p,X) reaction for 0.4-,
1.3-, 1.5-, 2.2-, and 3.0-GeV proton incidence at J-PARC. In this work, we successfully obtained
the 49 nuclides production cross sections. The uncertainty of most of the present data wassmaller than those in the preceding studies. Additionally, present data were compared with
INCL/GEM and JENDL/HE-2007 to confirm the prediction accuracy. Through the comparison,
it is absolutely found that they have room for improvement.
We will continue the data analysis for lighter nuclides production cross sections. Furthermore,
we pursue the key to improve the prediction accuracy of nuclear reaction models.

References[1] Kumada, H., et al., Project for the development of the linac based NCT facility in Universityof Tsukuba: Appl. Radiat. Isotope, 88 (2014), pp. 211-215.
[2] Lee, C.L., et al., A Monte Carlo dosimetry-based evaluation of the 7 Li(p,n)7 Be reaction
near threshold for accelerator boron neutron capture therapy: Med. Phys. 27 (1) (2000),
pp. 192-202.
[3] Otake, Y., RIKEN Compact Neutron Systems with Fast and Slow Neutrons: Plasma Fusion
Res. 13 (2018), 2401017.
[4] Kobayashi, T., et al., Completion of a new accelerator-driven compact neutron source prototype RANS-II for on-site use: Nucl. Instr. Methods A 994 (2021) pp. 1-6, 165091.
[5] Furusaka, M., et al., Activity of Hokkaido University Neutron Source, HUNS: Phys. Procedia, 60 (2014), pp. 164-174.
[6] Baxter, D.V., et al., LENS: 2013 Facility Overview: Phys. Procedia, 60 (2014), pp. 175-180.
[7] Sugawara, T., et al., Conceptual design study of beam window for accelerator-driven systemwith subcriticality adjustment rod: Nucl. Eng. Des., 331 (2018), pp. 11-23.
[8] Tsujimoto, K., et al., Neutronics Design for Lead-Bismuth Cooled Accelerator-Driven System for Transmutation of Minor Actinide: J. Nucl. Sci. Technol. 41 (2004), pp. 21-36.
[9] Cui, W., et al., Temperature control for spallation target in accelerator driven system: Nucl.
Instr. Methods B 448 (2019) pp. 5-10.

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JAEA-Conf 2023-001[10] Preston, M., et al., Analysis of radiation emission from MYRRHA spent fuel and implications for non-destructive safeguards verification: Annals of Nucl. Energy, 163, (2021),
108525.
[11] Boudard, A., et al., New potentialities of the Liège intranuclear cascade model for reactions
induced by nucleons and light charged particles: Phys. Rev. C 87, (2013), 014606.
[12] Furihata, S., Statistical analysis of light fragment production from medium energy protoninduced reactions: Nucl. Instrum. Meth. B 171 (2000), pp. 251-258.
[13] Sato, T., et al., Features of Particle and Heavy Ion Transport code System (PHITS) version
3.02: J. Nucl. Sci. Technol. 55 (2018), pp. 684-690.
[14] Watanabe, Y., et al., Status of JENDL high energy file: J. Korean Phys. Soc., 59 (2011),
pp. 1040-1045.
[15] Titarenko, Yu.E., et al., Experimental and theoretical studies of the yields of residual
product nuclei produced in thin Pb and Bi targets irradiated by 40 - 2600 MeV protons:
INDC(CCP)-0447.
[16] Gloris, M., et al., Proton-induced production of residual radionuclides in lead at intermediate energies: Nucl. Instr. Methods A 463 (2001) pp. 593-633.
[17] Hotchi, H., et al., Beam commissioning of the 3-GeV rapid cycling synchrotron of the Japan
proton accelerator research complex: Phys. Rev. ST Accel. Beams, 12 (2009), 040402.
[18] Hotchi, H., et al., Achievement of a low-loss 1-MW beam operation in the 3-GeV rapid
cycling synchrotron of the Japan proton accelerator research complex: Phys. Rev. Accel.
Beams, 20 (2017), 060402.
[19] Matsuda, H., et al., Proton-induced activation cross section measurement for aluminumwith proton energy range from 0.4 to 3 GeV at J-PARC: J. Nucl. Sci. Technol., 55 (8)(2018), pp. 955–961.
[20] Takeshita, H., et al., Measurement of nuclide production cross sections for proton-induced
reactions on Mn and Co at 1.3, 2.2, and 3.0 GeV: Nucl. Instr. Methods B 511 (2022), pp.
30-41.
[21] Takeshita, H., et al., Measurement of nuclide production cross sections for proton-induced
reactions on nat Ni and nat Zr at 0.4, 1.3, 2.2, and 3.0 GeV: Nucl. Instr. Methods B 527(2022), pp. 17-27.
[22] Meigo, S., et al., Evaluation of the 3-GeV proton beam profile at the spallation target of
the JSNS: Nucl. Instr. Methods A 562 (2006) pp. 569-572.
[23] Meigo, S., et al., Beam commissioning for neutron and muon facility at J-PARC: Nucl.
Instr. Methods A 600 (2009) pp. 41-43.
[24] Gloris, M., et al., Production of residual nuclei from irradiation of thin Pb-targets with
protons up to 1.6 GeV: Nucl. Instr. Methods B 113 (1996) pp. 429-433.
[25] Yashima, H., et al., Cross sections for the production of residual nuclides by high-energy
heavy ions: Nucl. Instr. Methods B 226 (2004) pp. 243-263.
[26] Ju, Y.Q., et al., The production of residual radionuclides by a 250 MeV proton beam: J.
Phys. G: Nucl. Part. Phys. 42 (2015), 125102.

Acknowledgments
This paper includes results obtained with the Subsidy for Research and Development on
Nuclear Transmutation Technology.

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JAEA-Conf 2023-001

13.

Improvement of Benchmark Experiment with Gold foil for Large Angle Scattering Reaction
Cross Section at 14 MeV Using Two Shadow Bars

Rio Miyazawa, Sota Araki, Indah Rosidah Maemunah, Shingo Tamaki, Sachie Kusaka, Isao Murata
Department of Sustainable Energy and Environmental Engineering, School of Engineering,Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japane-mail: miyazawa22@qr.see.eng.osaka-u.ac.jp
Currently, fusion reactors are expected to be future energy resources. And a lot of fusion neutronics related
experiments have been conducted so far for the neutronic design. However, improvement of nuclear data isthought to be still needed for the development of fusion reactors. To solve this problem, we established a new
benchmark experimental method to verify large angle scattering cross section. However, the previous
benchmark experimental system using Nb as a neutron detector by employing 93Nb(n,2n)92Nb reaction
required a lot of time for irradiation and measurement. In this study, the feasibility of the benchmark method
using 197Au (n,2n) 196Au reaction instead of niobium reaction was examined. The gold reaction has a larger
reaction cross section and a shorter half-life, and was expected to become a better method for benchmarking
large angle scattering cross section of nuclear data.
In the new benchmark experimental method with gold foil, reaction rates of 197Au (n,2n) 196Au need to be
calculated. However, because 197Au (n,2n) 196Au has two excited levels with long half-lives, it is impossible
to calculate the exact reaction rates. Therefore, an appropriate experimental procedure using gold foil was
examined by numerical simulations. After that, benchmark experiments of large-angle scattering crosssection using Au were performed for tungsten, and the results were compared with the performance of theconventionally obtained result with Nb foil.
As a result of the numerical simulations, it was found that benchmark experiments can be analyzed bysumming up the ground state 196Au production cross section and two excited levels 196Au production crosssections to be as the total production cross section of 196Au. These apparent reaction rates were confirmed to
be almost the same as the theoretically exact values. Also, as a result of the benchmark experiments, it showsthat the measurement time required to obtain the same statistical accuracy can be reduced by a factor of atleast 2 compared to the conventional method with Nb foil.
1. Introduction
For high energy incident neutrons, the large angle scattering cross section is usually not so importantbecause it is much smaller than the forward scattering cross section. However, in high-intensity neutron fields
such as fusion reactors, it cannot be neglected in neutron transport calculation due to gap streaming
phenomenon in the blanket and so on. Actually, disagreement between calculated and experimental values
has been reported in benchmark experiments at Fusion Neutronics Source (FNS) at Japan Atomic Energy
Agency by Ohnishi et al., and uncertainty in the large-angle scattering cross section has been pointed out [1].

- 86 86

JAEA-Conf 2023-001)LJXUH (ODVWLFVFDWWHULQJFURVVVHFWLRQRI :)LJXUH &RPSDULVRQRI$XDQG1EDFWLYDWLRQFURVVVHFWLRQV
In fact, as shown in Figure 1, the elastic scattering cross sections of tungsten (184W), which is planned to be
used in fusion reactor diverters, show different magnitudes especially for large scattering angles >@.
Usually, benchmarking of elastic scattering is carried out by integral experiments. However, at backward
angles, it is difficult to carry out the benchmark experiment due to small cross sections for backscatter. In
response to this problem, the author's group developed a benchmark method for large angle scattering crosssections using shadow bars >@. The benchmark experimental system has so far employed niobium foil as
an activation detector by 93Nb(n,2n)92Nb reaction. However, in the measurement using niobium foil, it was)LJXUH([FLWHGOHYHOVLQ $X QQ

- 87 87

JAEA-Conf 2023-001

problematic that it takes a very long time to measure and sufficient γ-ray counts for proper evaluation may
not be obtained for some experimental systems. To solve this problem, it is considered to use gold foil insteadand the activity of 197Au (n,2n) 196Au is used for the evaluation, because this reaction has a larger activation
cross section than niobium reaction as shown in Figure 2 and its half-life of 196Au produced by 197Au (n,2n)
Au is about two times shorter than that of 92Nb produced by 93Nb(n,2n)92Nb [7]. However, 196Au generated

196

in the reaction has two excited levels with long half-lives as shown in Figure 3 and it is impossible to calculate
exact reaction rates [8]. Therefore, the objective of the present research is to examine the feasibility ofmeasurement with gold foil. This research is expected to shorten the measuring time for benchmark
experiments and to obtain stable γ-rays counts. Benchmark experiments of large angle scattering crosssections of tungsten were also performed using gold foil, and the obtained results were compared with theconventional benchmark experiments with niobium foils to evaluate the feasibility of the experiment using
gold foil.
2. Methods and Theories
The present benchmark experimental method using two shadow bars is described in this section. The
benchmark experimental system consists of four irradiation experiments, including the two systems shownin Figure 4 and two systems for each in which the target sample is removed. The large angle scattering crosssections are benchmarked by subtracting the reaction rates obtained for each of these four experimental
systems. The reaction rate is calculated by Equation (1).
𝑁𝑁

Reaction rate(RR) = 𝑉𝑉𝐴𝐴 ∫𝐸𝐸 𝜎𝜎 𝜙𝜙𝜙𝜙𝜙𝜙(1)

NA is the number of foil atoms, V is the volume of foil, О is the activation cross section of foil, 𝜙𝜙 is theneutron flux at foil. As shown in Figure 5, the three components of the experimental system are the shadowbar, the wall, and the target, so as in Figure 5 there are seven paths available through which neutrons cantransport before reaching the activation foil. Path 3 in Figure 5 is the path of interest, by which neutrons arescattered in the target with a large angle, and the nuclear data libraries can be benchmarked by comparing theobtained reaction rates in this path between experiments and simulations [5]. If the respective four systems
are named S1TC, S1C, S2TC, and S2C, the path contributions that neutrons can take in each system can be
expressed as described in Figure 6. The reaction rate of path 3 is thus obtained from the reaction rates ofthese four irradiation experiments by Equation (2).

)LJXUH 7ZRW\SHVRIH[SHULPHQWDOV\VWHPIRUEHQFKPDUN- 88 88

JAEA-Conf 2023-001)LJXUH  3DWKVRIWUDQVSRUWLQJQHXWURQVLQ
WKHEHQFKPDUNV\VWHP)LJXUH3RVVLEOHSDWKVLQHDFKH[SHULPHQWDOV\VWHP
)=

(

(

)

( )

In this case, the reaction rates of paths 2 and 7 are very small compared to path 3, so they are treated as
evaluation errors.

Normally, the reaction rate can be expressed by Equation 1, but as described in Section 1, the exact reaction
rate cannot be calculated in the benchmark experiment if using gold. Therefore, in the present study weassumed that the gold activity could be evaluated by the apparent reaction rate in Equation 3, and tried toverify whether it could approximate the real value with an acceptably small discrepancy by using MCNP[9].
Reaction rate(RR) =

𝑁𝑁𝐴𝐴
𝑉𝑉

∫𝐸𝐸(𝜎𝜎𝜎𝜎𝜎𝜎 ) 𝜙𝜙𝜙𝜙𝜙𝜙( )In the equation, О0 is the cross section of ground level production in Figure 3,О1 is the cross section of theexcited level with the half-life of 8.1 s, and О2 is the cross section of excited level with the half-life of 9.6
h. Specifically, the accuracy of this approximation was evaluated by calculating the relative error between
the numbers of 196Au excited by the apparent activation cross section in Equation 3 and the exact activation
cross section as shown in Figure 3.
3. Results
Figure 7 shows the discrepancy of the number of excited 196Au by the apparent cross section in Equation 3compared to the result by the exact activation cross section for the irradiation and cooling time. This figure
shows that the relative error is less than 0.4% regardless of these times, and is sufficiently small compared tothe error in the γ-ray counts. Therefore, it was found appropriate to evaluate the number of excited 196Au by
the apparent reaction rate by using Equation 3.
Based on these results, benchmark experiments with a tungsten target were conducted using a gold foil. In
the experiments, the dimensions of the foil were 2 × 2 × 0.25 cm3. A niobium foil was additionally used
together with the gold foil to compare the experimental results and performance with that of the niobium foil.
The shape of the niobium foil was a cylinder with a height of 0.5 cm and a diameter of 1.5 cm. The
experimental results are shown in Table 1. The simulation results were calculated using the nuclear datalibraries, JENDL-4.0, ENDF-B/ᶠ, and JEFF-3.3.

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JAEA-Conf 2023-001)LJXUH 7KHUHODWLYHHUURURIWKHQXPEHURIJURXQGVWDWH $X)LJXUH  5DWLRRI WKH PHDVXULQJWLPH RI1EIRLOWR $X IRLO
IRUJLYHQVWDWLVWLFDOHUURUVIRU67&
As shown in the results, it is found that C/E values which mean the uncertainty of large angle cross-section
data show no significant difference between those using niobium and gold foils. Also, the final experimental
results deduced with Equation 1 are larger than the simulation ones. This result suggests possible
underestimation of the large angle scattering cross section in the nuclear data libraries. It is also presumed
that large difference observed between the experimental and simulation values in the four experimental
7DEOH  $X QQ $XDQG 1E QQ 1E5HDFWLRQUDWHVLQWKHWXQJVWHQWDUJHWH[SHULPHQWV>UHDFWLRQVRXUFHQHXWURQFP@- 90 90

JAEA-Conf 2023-001

systems are due to the fact that the calculation system does not take desks supporting the shadow bar,
accelerator itself, etc. into consideration. Figure 8 shows the ratio of required measurement times of Nb to
Au for given statistical errors of γ-ray counts for the irradiation experiment of the S2TC system, which is
expected to have the smallest number of counts. It shows that the measurement time required to obtain thesame statistical accuracy by gold foil can be reduced by a factor of at least two compared to niobium foil.
4. Conclusion
In this study, improvement of benchmark experimental method for large angle scattering reaction crosssection at 14MeV was conducted, because the previously used benchmark experimental method employed aniobium foil with 93Nb(n,2n)92Nb reaction, and in this case, it required a lot of time for the irradiation andmeasurement. We employed gold foil instead of niobium, because the reaction products by it has a larger
reaction cross section and a shorter half-life compared to reaction products by niobium foil. As a result of
numerical and experimental analyses, it was found that benchmark experiments could be properly performed
using gold foil as a detector regardless of the irradiation and cooling time. Moreover, the measurement time
can be reduced by a factor of at least two compared to the conventional method with niobium. In the future,benchmark experiments will be conducted for carbon and other nuclides using gold foil.
References[1] S. Ohnishi et al.: New integral experiments for large angle scattering cross section data benchmarking
with DT neutron beam at JAEA/FNS, Fusion Engineering and Design, 87, pp. 695-699 (2012).
[2] NEA, ” JEFF-3.3”, https://www.oecd-nea.org/dbdata/jeff/jeff33/index.html (accessed 2022-02-06).
[3] K. Shibata, et.al. : "JENDL-4.0: A New Library for Nuclear Science and Engineering," J. Nucl. Sci.
Technol. 48(1), 1-30 (2011).
[4] D.A. Brown, M.B. Chadwick, R. Capote, et al., "ENDF/B-VIII.0: The 8th Major Release of the Nuclear
Reaction Data Library with CIELO-project Cross Sections, New Standards and Thermal ScatteringData", Nuclear Data Sheets, 148: pp. 1-142 (2018).
[5] Naoya Hayashi, Seiki Ohnishi, Yuki Fujiwara, Sachie Kusaka, Fuminobu Sato, Isao Murata“Optimization of Experimental System Design for Benchmarking of Large Angle Scattering Reaction
Cross Section at 14 MeV Using Two Shadow Bars” Plasma and Fusion Research, 13, 2405002, (2018).
[6] Atsuki Yamaguchi, et.al., " Benchmark experiment of large-angle scattering reaction cross section ofiron at 14 MeV using two shadow bars – Comparison of experimental results with ENDF/B-VIII –"Journal of Nuclear Science and Technology, 58. pp. 80-86 (2019).
[7] Y. Nakajima, JNDC WG on Activation Cross Section Data: “JENDL Activation Cross Section File,”
Proc. the 1990 Symposium on Nuclear Data, JAERI-M 91-032, pp. 43 (1991).
[8] Richard B. Firestone, et al, Table of Isotopes Eighth Edition Volume Ⅱ, pp. 2453.
[9] Brown, F.B., MCNP-A General Monte Carlo N-Particle Transport Code, Oak Ridge(US): Los Alamos
National Laboratory; 2003.

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14.

The comparison of nuclear data and experimental results forphotoneutron spectra on Ta, W, and Bi targets for 17 MeV photons*T. NGUYEN1, T. SANAMI1,2, H. YAMAZAKI1,2, Y. SAKAKI1,2, T. ITOGA3, Y. KIRIHARA4,
K. SUGIHARA1,2, M. FAIZ1, S. MIYAMOTO5, S. HASHIMOTO6, Y. ASANO2,7.
1

SOKENDAI, Shonan Village, Hayama, Kanagawa 240-0193 Japan
2KEK, 1-1 Oho, Tsukuba-shi, Ibaraki-ken 305-0801 Japan

3JASRI, 1-1-2, Koto, Kamigori-cho, Ako-gun, Hyogo 678-1205, Japan
4JAEA, 2-4 Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195, Japan
5 ILE, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871, Japan
6University of Hyogo, 1-1-2, Koto, Kamigori-cho, Ako-gun, Hyogo 678-1205, Japan
7 RCNP, Osaka University, 10-1, Mihogaoka, Ibaraki, Osaka 567-0047, Japan*Email: ngthuong@post.kek.jp

The photoneutron energy spectra obtained from nuclear data and theoretical calculations werecompared with the experimental data for 17 MeV photons on Ta, W, and Bi targets. The results of PHITS
code, CoH3 code, JENDL/PD-2016 nuclear data, and TENDL-2019 nuclear data were included for thiscomparison.

1. Introduction
High-energy photons are primarily produced as bremsstrahlung by electron accelerators. Secondary
neutrons can be emitted via photonuclear reactions from the interactions between these photons andaccelerator components. Data of photoneutron yield, energy, and angular distribution are fundamental
parameters for the shielding design of electron accelerators.
So far, several studies have been conducted on neutron emission in photonuclear reactions [1 , 2, 3].
Our group recently measured the photoneutron spectra for 17 MeV linearly polarized photons at angles
ranging from 30° to 150° on Ta, W, and Bi targets. The results consist of low-energy and high-energy
components. The angular distribution of the low-energy component was isotropic, whereas the highenergy component was dependent on the interaction angle between photon polarizatio n and neutron
emission.
The measured data are important for benchmarking the nuclear data and theoretical calculations.
Thus, in this study, the experimental results on Ta, W, and Bi targets irradiated by 17 MeV photons werecompared with photoneutron spectra obtained by the theoretical codes of PHITS [4] and CoH3 [5], andnuclear data libraries of TENDL-2019 [6], JENDL/PD-2016 [7].

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JAEA-Conf 2023-001

2. Experiment
Our experiment was carried out at NewSUBARU facility, BL-01, Hyogo, Japan. Figure 1 shows theexperimental setup of the photoneutron measurement, as mentioned in [1]. The mono-energetic,
horizontally polarized photon beam was produced by the collision of a polarized laser source and 1 GeVelectron at the backscattering angle. The beam was adjusted to inject into the center of the target. Targets
were cylinders with 1 cm thicknesses for Ta and W and 2 cm for Bi. A 5-mm-thick plastic scintillator
was placed upstream of the target to estimate the number of incident photons. Six liquid scintillation
detectors (NE213, 5 × 5L in) were positioned at 30°, 60°, 90°, 120°, and 150° horizontally and 90°
vertically to the photon beam direction. Because of the high sensitivity of NE213 to photoneutrons andgamma in the background, the pulse shape discrimination (PSD) technique was used. The time-of-flight(TOF) method was applied for obtaining the photoneutron energy spectra.

Plastic scintillator

TargetIncident photon beam

Figure 1: The experimental setup of photoneutron measurement [1].
To acquire data, a system including a charge-to-digital converter (QDC) module, a time-to-digitalconverter (TDC) module, and a VME controller was prepared, which was identical to that used in previous
experiments [1, 2]. The QDC module recorded the tail and total charges of the output signals from NE213,
and the TDC module recorded the time difference between the incident photons and signals detected byNE213. A two-dimensional plot of the charge ratio of the tail and total signals, defined as the PSD
parameter, and time-of-flight was used to distinguish photoneutrons and background gamma, as shownin Figure 2. Events with light yield greater than 0.25 MeVee - equivalent to half of the 137Cs bias, wereselected. Figure 3 shows the neutron-gamma time-of-flight spectra after neutron and gamma separation.
The neutron detection efficiency of the detectors was calculated using the SCINFUL-QMD simulation[8] with correction of the neutron measurement from the 252Cf source. The attenuation of the photon beam
due to the target thickness was evaluated using the PHITS code.
The experimental data showed the polarization effect of the incident photons same as previous- 93 93

JAEA-Conf 2023-001

experiment [1, 2]. Hence, in this paper, we only reported the photoneutron spectra at the vertical 90°
position (V90) for comparison, to exclude the polarization effect.

3. Theoretical calculations and nuclear data libraries
In this work, the photoneutron spectra from the theoretical codes of PHITS and CoH 3 and thenuclear data libraries of TENDL-2019 and JENDL/PD-2016 were compared with the measured data. We
used PHITS version 3.27 with the default mode and the same geometry as the experiment. The detection
regions were simulated as cylinders with a size of 5 × 5 in, without NE213 liquid in volume. The same
geometry as that of the PHITS code was used to obtain neutron spectra using TENDL -2019 nuclear datalibraries instead of the default reaction models. The neutron spectra from JENDL/PD-2016 were directly
derived using the ENDF-6 reader program [9]. Neutron spectra were obtained using the CoH 3 code in the
double-differential calculation mode without considering the experimental geometry. Because the results
obtained from the CoH 3 code and JENDL/PD-2016 nuclear data library are whole neutrons emitted on aplane perpendicular to the incident photon beam direction, their magnitude must be adjusted forcomparison with experimental data.
NeutronFigure 2: Neutron-gamma separation using the charge ratio between slow and total gates on Bi target
at vertical 90° position.
Gamma peak

NeutronFigure 3: Neutron and gamma time-of-flight spectra on Bi target at vertical 90° position.

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JAEA-Conf 2023-001

4. Result and discussion
Figure 4 shows the photoneutron energy spectra obtained from the experiment, PHITS default
calculation, CoH 3 code, and nuclear data libraries of TENDL-2019 and JENDL/PD-2016 for W, Ta, andBi targets. The red circles indicate the experimental data at a 90° angle perpendicular to the polarization
direction with respect to the incident photon. The measured spectra consist of low - and high-energy
components.

Figure 4: Photoneutron energy spectra for 17 MeV photons on W, Ta, and Bi targets.
All the theoretical calculations and nuclear data underestimate the experimental data. They show
approximately identical results below 4 MeV, and a noticeable difference in the region above 4 MeV. The
slopes of the PHITS default calculation (black solid lines) are the lowest among all the results. The PHITS
results with the default model contain only the low-energy evaporation component that originates fromthe Generalized Evaporation Model (GEM) [10] for 17 MeV photons. The calculations using the

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JAEA-Conf 2023-001

CoH3 code are close to the experimental data for Ta and W, but low for Bi. The green and blue solid lines
representing the results extracted from the TENDL-2019 and JENDL/PD-2016 nuclear data, respectively,
are similar for Bi. However, for Ta and W, the spectra obtained by TENDL-2019 are higher than thoseobtained by JENDL/PD-2016.

5. Conclusion
We compared the photoneutron energy spectra from the nuclear data libraries of TENDL-2019 and
JENDL/PD-2016, theoretical calculations of PHITS and CoH 3, and measurements. The results showedsignificant differences among the theoretical calculations, nuclear data, and experimental data in the high energy region. Thus, all theoretical models and nuclear data must be improved to accurately describe thephotonuclear reactions.

References
1)

Tuyet, T.K., Sanami, T., Yamazaki, H., Itoga, T., Takeuchi, A., Namito, Y., Miyamoto, S. and2)

Asano, Y., Energy Energy and angular distribution of photo-neutrons for 16.6 MeV polarized
photon on medium–heavy targets, Nucl. Instrum. Meth. A, vol.989, 2021, 164965.
Kirihara, Y., Nakashima, H., Sanami, T., Namito, Y., Itoga, T., Miyamoto, S., Takemoto, A.,
Yamaguchi, M. and Asano, Y., Neutron emission spectrum from gold excited with 16.6 MeV
linearly polarized monoenergetic photons, vol.57, no.4, J. Nucl. Sci. Technol., 2020, pp.444-

3)

456.
Varlamov, A.V., Varlamov, V.V., Rudenko, D.S. and Stepanov, M.E., Atlas of giant dipole
resonances. Parameters and Graphs of Photonuclear Reaction Cross Sections. INDC (NDS)394, IAEA NDS, Vienna, Austria, 1999, pp.1-311.

4)

5)
6)

7)
8)

9)

Sato, T., Iwamoto, Y., Hashimoto, S., Ogawa, T., Furuta, T., Abe, S.I., Kai, T., Tsai, P.E.,
Matsuda, N., Iwase, H. and Shigyo, N., Features of particle and heavy ion transport code system(PHITS) version 3.02, vol.55, no.6, J. Nucl. Sci. Technol., 2018, pp.684-690.
Kawano T., Proc. of the 6th Int. Workshop on Compound-Nuclear Reactions and Related
Topics CNR*18, 2019, p. 27.
Koning, A.J., Rochman, D., Sublet, J.C., Dzysiuk, N., Fleming, M. and Van der Marck, S.,TENDL: complete nuclear data library for innovative nuclear science and technology, Nuclear
Data Sheets, 155, 2019, pp.1-55.
Iwamoto, N., Kosako, K., Murata, T., Photonuclear Data File, JAEA-Conf 2016-004, 2016, pp.
53-58.
Satoh, D., Kunieda, S., Iwamoto, Y., Shigyo, N. and Ishibashi, K., Development of SCINFUL QMD code to calculate the neutron detection efficiencies for liquid organic scintillator up to 3
GeV, J. Nucl. Sci. and Technol., vol.39, 2002, pp.657-660.
Sakaki, Y., Note on Evaluated Nuclear Data Library and a new tool “endf6 reader”, KEK,
2020.

10) Furihata, S., Statistical analysis of light fragment production from medium energy protoninduced reactions., Nucl. Instrum. and Meth. B, vol.171, no.3, 2000, pp. 251-258.

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15. Study of GAGG scintillator as a neutron detector
Ren Sakai1 and Nobuhiro Shigyo1
1

Department of Applied Quantum Physics and Nuclear Engineering, Kyushu University
744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
Email: sakai.ren.063@s.kyushu-u.ac.jp∗

In order to use the GAGG scintillator as a neutron detector, the signatures of neutron detection were investigated. Various conditions were simulated using PHITS to determine the size of
GAGG scintillator. The response characteristics when neutrons of some energy are incident on
the GAGG scintillator are simulated by changing the thickness of the GAGG scintillator from
0.1 to 100 mm. We also investigated the neutron energy dependence of the GAGG scintillator
by changing the incident neutron energy from 1 meV to 10 MeV. Furthermore, the size of the
GAGG scintillator was determined from the simulation results, and the response to thermal
neutrons was measured.

1.

Introduction

In recent years, there is a need for improved nuclear data on high-energy neutron-induced
fission of actinides [1]. For example, improving the data of prompt neutrons will contribute tonuclear applications [2]. Even in thermal neutron detection, 3 He does not exist naturally and isvery expensive and its price has continued to rise due to changes in nuclear security policies in
the United States, making it difficult to obtain 3 He in recent years [3, 4]. For these reasons, it isnecessary to explore for new neutron detectors.
The GAGG scintillator emits a large amount of light and is excellent as a gamma-ray detector,
and is used in single-photon emission tomography SPECT, gamma cameras. Gd, a constituent
element of GAGG, has isotopes with fairly large capture cross-sections for low-energy neutrons.
Among them, 155 Gd and 157 Gd have particularly large cross sections for thermal neutrons of
60,740 b and 253,700 b, respectively as shown in Fig. 1, and natural abundance ratios of 14.8
% and 15.7 %, respectively. The reaction transition of each isotope can be expressed as follows,
and the Q values are 8.1 and 7.9 MeV, respectively. For neutrons above 100 keV, signals due
to inelastic scattering can also be expected for neutron detection. For these reasons, it may be
used as a neutron detector.
155
157

Gd + n →156 Gd∗ →156 Gd + γ
Gd + n →

158

Gd →
∗

158

Gd + γ(1)(2)

Our purpose is to verify the performance of the GAGG scintillator as a neutron detector.
We would like to detect neutrons in the thermal neutron region and neutrons above 100 keV.
For that purpose, we first analyzed the response of the GAGG scintillator to various energy
neutrons using the 3D Monte Carlo code PHITS [6]. Thermal neutron irradiation experiments
were also carried out to investigate the thermal neutron response of the GAGG scintillator.

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JAEA-Conf 2023-001

Fig. 1

Neutron capture cross section of Gd isotopes in JENDL-4.0 [7].

2.

Simulation of r neutron responses of GAGG scintillator

2.1

Calculation condition

PHITS ver.3.27 was used as the simulation code. JENDL-4.0 [7] was used for neutron
reactions, and EGS5 [8] was used for electron, positron, and photon transport. In this section,
we discuss the response dependence of the GAGG scintillator on the GAGG scintillator thickness
and the incident neutron energy. The area of the GAGG scintillator is fixed a t 2 × 2 c m2 . The
number of histories was set to 6 × 106 .
The response was simulated for incident neutron energies from 1 meV to 10 MeV and GAGG
scintillator thicknesses of 0.1 mm, 1 mm, 1 cm and 10 cm. The obtained calculations are
the neutron flux in the GAGG scintillator, the spectrum of neutrons and photons in the GAGG
scintillator, and the energy distribution due to particles such as electrons imparted to the GAGG
scintillator.

2.2

Results

From neutron flux, t he n eutron r eaction r ate w as c alculated b y d ividing t he n eutron flux
exiting the GAGG scintillator by the neutron flux entering the GAGG s cintillator. The detection
efficiency wa s ca lculated by ta king th e su m of el ectrons im parted wh en ne utrons of a certain
energy were incident on the GAGG scintillator from the deposit energy distribution. The neutron
flux and the energy distribution of electrons imparted to the GAGG scintillator for 1 meV to 10
MeV neutrons were summarized for each GAGG scintillator thickness, and graphs of the neutron
reaction rate and detection efficiency we re dr awn. Th ese ar e sh own in Fi gs. 2 an d 3. In both
figures, it can b e inferred that the resonance part of the capture cross section is reflected in therange of about 1 eV to 1 keV.
In addition, from the results shown in Figs. 2 and 3, for thermal neutrons, the thicknessof 0.1 and 1 mm shows a certain sensitivity, but compared to 1 cm and 10 cm, the sensitivity
to neutrons with energy higher than 1 eV is much lower. Therefore, we determined that the
optimum thickness of the GAGG scintillator was approximately 1 cm.

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JAEA-Conf 2023-001

Fig. 2

3.

Neutron reaction rate.

Fig. 3Detection efficiency.

Thermal neutron irradiation experiment

Using the GAGG scintillator, thermal neutrons measured before measuring fast neutrons.
Cadmium difference method was used to investigate the response to thermal neutrons.

3.1

Data acquisition and circuit system

The dimension of GAGG scintillator used in this experiment has an area of 2 × 2 cm2 and a
thickness of 1 cm. This scintillator was wrapped in PTFE tape to improve light collection. The
PMT used in this work was a HAMAMATSU H6410. We used four 252 Cf neutron sources. At
the time of measurement, the total source intensity was 7.1 MBq.
All γ ray and neutron data were acquired with a DT5742 CAEN digitizer. The PMT bias
was 2002 V. Logic signals of a CFD were used as fast triggers when recording waveforms. We
set the CFD threshold at the lower limit of -30 mV. This circuit system is shown in Fig. 4.

Fig. 4

3.2

Circuit system.

Experiment preparation

The detector was calibrated using the γ rays from 241 Am, 109 Cd, and 137 Cs. The photopeaksof 241 Am, 109 Cd, and 137 Cs are 59.5, 88 and 661.7 keV, respectively.

The neutron sources used in this work were produced from four 252 Cf sources discribed above.
In order to irradiate the GAGG scintillator with thermal neutrons, the distance from the source
to the scintillator was set at 16 cm, and a polyethylene block with a thickness of 10.4 cm wasplaced between them. In addition, a 5 cm thick lead was placed in front of the scintillator toshield γ rays from the 252 Cf sources.

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JAEA-Conf 2023-001[t-track] in xyz mesh

File = track_xz.dat

Date = 11:19 10-Jan-2023

However, in this system, higher energy neutrons
no. = 1, ie = 1, iy = 1
above 100 keV came to the GAGG scintillator in addition to thermal neutrons. Therefore, we investigated
20 × 20 × 0.1 cm3
10
Cd board
the response due to thermal neutrons by using the Cd
252Cf neutron source
Region ofdifference method. In this method, measurements were
GAGG
taken for the same amount of time with and without
0
the Cd plate, and thermal neutron data are obtained
from the difference. Figure 5 shows a system in which
20 × 10 × 5 cm3
a 10.2 cm thick polyethylene block, a 5 cm thick lead
−10
lead block
20 × 10.2 × 5.2 cm3block, and a 2 mm thick Cd plate are placed between thepolyethylene blocksource and the GAGG scintillator. In addition to the
0
5
10
15
z [cm]
two systems mentioned above, we calculated the neutron spectra irradiated to the GAGG scintillator using
PHITS, assuming that nothing is placed between theFig. 5 Simulation system when a 2
source and the GAGG scintillator, which is shown inmm thick Cd plate is placed between
Fig. 6. The light blue line is the neutron spectrum
polyethylene and leadwhen nothing is placed between the source and the detector, the brown line is the neutron spectrum when apolyethylene block and a lead block are placed. The yellow lines represent the neutron spectrum
when a Cd plate is added to the brown line system. It can be seen that most of the thermal
neutrons have been captured by Cd plate.
x [cm]

emin = 0.0000E+00 [MeV]emax = 2.0000E+01 [MeV]ymin = -1.6500E+01 [cm]ymax = 1.6500E+01 [cm]part. = neutron

void

11

13

12

10

2
4
3

90

calculated by PHITS 3.27

Fig. 6Comparison of neutron spectra in the GAGG region.

3.3

Results

3.3.1

Energy calibration of gamma-ray sources

Waveform data were collected using gamma-ray sources : 241 Am, 109 Cd, and 137 Cs. Figure
7 shows a comparison of the amount of light yield calculated from each waveform data for each
γ ray source. Energy resolution is approximately 22.5 % at 59.5 keV, 19.5 % at 88 keV, and 6.3% at 661.7 keV. An energy calibration curve is shown in Fig. 8.

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JAEA-Conf 2023-001

Fig. 73.3.2

γ ray source spectra.

Fig. 8Energy calibration curve.

Thermal neutron measurements

We acquired the waveform data for 30 minutes for cases with and without the Cd plate. In
Fig. 9, the brown line is the data measured in the system without the Cd plate, the yellow lineis the data measured in the system with the Cd plate, and the blue line is the data obtained
from the difference between them. The combined 1st excited state to ground state transitionsfor 156 Gd and 158 Gd at 84.6 keV is the most prominent feature. In addition, two higher energy
features are also observed at 263 keV and 454.1 keV.
The 84.6 keV peak is the combination of the 88.9 and 79.5 keV γ rays from the first excitedstates of 156 Gd and 158 Gd, which cannot be separately resolved. In Fig. 9, we also observe a
γ peak at 263 keV, this is a result of the rotational band structure of both 156 Gd and 158 Gd in
which the 4+ state de-excites in sum-coincidence through the 2+ state to the ground state.

Fig. 9 Light yield spectrum obtained by taking the difference between the data without theCd plate and the data with the Cd plate.

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JAEA-Conf 2023-001

4.

Summary

To investigate whether GAGG can be used as a neutron detector, we calculated the responseusing PHITS and measured the response to thermal neutrons. From the simulation results, it
was found that the optimum thickness of the GAGG scintillator for neutron spectroscopy using
the TOF method is approximately 1 cm.
Based on these results, we carried out the thermal neutron irradiation experiment using 1
cm thick of GAGG scintillator. For thermal neutrons, three useful signals for neutron detection
were confirmed. In the future, we plan to measure the TOF spectrum using the 252 Cf neutron
source and verify its performance as a detector for fast neutron components.

References[1] Neudecker D, Talou P, Kawano T, Kahler AC, et al. Evaluations of Energy Spectra of
Neutrons Emitted Promptly in Neutron-induced Fission of 235U and 239Pu. Nucl Data
Sheets 2018;148:322–337.
[2] Neudecker D, Taddeucci TN, Haight RC, et al. The Need for Precise and Well-documented
Experimental Data on Prompt Fission Neutron Spectra from Neutron-induced Fission of
239Pu. Nucl Data Sheets 2016;131:289–318.
[3] Block T, Gruber M, Gurbuz S, et al. Particle physics readout electronics and novel detector
technologies for neutron science. Nucl Instrum Meth A 2023;1046:167753.
[4] Nadeera Hemamali GM, Smith DR, Hobson PR, et al. Europium doped Gd2O3 and GdBO3
scintillators for thermal neutron detection. Nucl Instrum Meth A 2023;1048:267918.
[5] Taggart MP, Nakahostin M, Sellin PJ. Investigation into the potential of GAGG:Ce as aneutron detector. Nucl Instrum Meth A 2019;931:121–126.
[6] Sato T, Iwamoto Y, Hashimoto S, et al. Features of Particle and Heavy Ion Transport code
System (PHITS) version 3.02. J Nucl Sci Technol. 2018;55(5-6):684–690.
[7] Shibata K, Iwamoto O, Nakagawa T, et al. JENDL-4.0: A New Library for Nuclear Scienceand Engineering. J Nucl Sci Technol. 2011;48:1–30.
[8] Hirayama H, Namito Y, Bielajew AF, et al. The EGS5 Code System. Stanford Linear Accelerator Center; 2005. (SLAC Report; SLAC-R-730), High Energy Accelerator
Organization; 2005. (KEK Report; 2005-8).

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16.

Characterization of various types of n-γ mixed fields
by using a D-D neutron source

Zixu XU1*, Masaya MATSUKI1, Kazuma AOKI2, Y瀂shihiro ARITOMO2, Shingo TAMAKI1, Sachie
KUSAKA1, and Isao MURATA1
1

Graduate School of Engineering, Osaka University
2-1 Yamadaoka, Suita, Osaka 565-0871, Japan

2Faculty of Science and Engineering, Kindai University

3-4-1 Kowakae, Higashiosaka, Osaka 577-8502, Japan*

Email: Xu.Zixu@qr.see.eng.osaka-u.ac.jp

Abstract: In the treatment field of Boron Neutron Capture Therapy (BNCT), secondary gamma-rays areeasily produced during neutron irradiation. In the BNCT project of Osaka University, a material-filtered
Radio-Photoluminescence Glass Dosimeter (RPLGD) was developed to measure neutron and gamma-ray
doses separately. In this study, to validate the material-filtered RPLGD for BNCT, various types of Fdominant, E-dominant, and T-dominant fields were designed by using a D-D neutron source. This paper
provides valuable reference n-γ mixed fields for developing radiation dosimeters for BNCT.

1. Introduction
1.1. Boron Neutron Capture Therapy
Boron Neutron Capture Therapy (BNCT) is a promising and rising technique for cancer therapy. In
BNCT [1], boron-10 compounds are concentrated in a tumor by boron delivery agents. After exposing apatient to thermal or epithermal neutrons, the tumor could be destroyed selectively in an effective mannerwithout damaging adjacent normal tissue [1]. In recent years, accelerator-based BNCT systems were
widely proposed and developed in many countries [2]. The neutron beams produced by accelerators
include contributions of secondary gamma-rays, as well as fast, epithermal, and thermal neutrons [1].
Because neutron and gamma-ray have different biological effects on human bodies [3], it is essential tomeasure the neutron and gamma-ray doses separately and simultaneously.
1.2. Objectives
Previously, researchers developed and measured different n-γ mixed fields for radiation experiments.
F. Ferrulli, et al. [4] developed an n-γ mixed field with an Am-Be source (1.5 mSv/h) and a 137Cs source(up to 60 μSv/h) to characterize a fast neutron dose rate detector. Yi-Chun Lin, et al. [5] measured the
gamma-ray and neutron dose rates for BNCT at two reactors (THOR and HFR). Ryo Ogawara, et al. [6]measured the absorbed dose contribution of thermal neutrons, fast neutrons, and gamma-rays at anaccelerator-based mixed field (p-Be source, Polyethylene moderator). However, there were few standard- 103 103

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n-γ mixed fields with adjustable gamma-ray to neutron dose ratios, classifications of dominant neutronenergy, and wide energy ranges of gamma-ray.
In the BNCT project of Osaka University, a liquid Li based neutron source is now planned to be
developed [7], and a material-filtered method of Radio-Photoluminescence Glass Dosimeter (RPLGD)
was proposed to separately measure neutron and gamma-ray doses for treatments [8]. However, there wasno standard n-γ mixed field for the authors to do validation experiments of the material-filtered RPLGD.
In this study, various types of n-γ mixed fields were designed by using a D-D neutron source (2.5 MeV)
at OKTAVIAN in the authors’ laboratory, as an alternative to cover the energy distribution of the p-Li
neutron source (0.6 MeV) [7].

2. Simulation setup and methods
2.1. Irradiation assembly
The irradiation assembly to generate n-γ mixed fields is shown in Figure 1. Source neutrons(isotropic, 2.5 MeV) were produced based on D(d,n)3He reaction. After the source neutrons penetrate themoderator, gamma-rays are produced to generate an n-γ mixed field. The moderator was 40 cm indiameter and 0-70 cm in thickness. The calculations were performed by Monte Carlo N-Particle Code 5(MCNP5) [9] based on ENDF/B-VIII.0 [10]. The number of source particles was set to 10 9. The radiation
fluxes and doses were calculated by F4 and F6 tallies, respectively. Six materials were considered tocompose the moderator: Al (2.70 g/cm 3), Fe (7.86 g/cm3), Pb (11.34 g/cm3), Polyethylene (PE) (0.93
g/cm3), CF2 (2.20 g/cm 3), and AlF3 (2.88 g/cm3). By changing the material, combination, and thicknessof the moderator, the radiation dose level and energy spectrum of the mixed fields were adjusted.

Figure 1. Irradiation assembly to generate n-γ mixed fields.
2.2. Gamma-rays produced at a neutron-generating target
When D-D source neutrons are produced and penetrate a neutron-generating target, gamma-rays areproduced by capture and inelastic scattering reactions, which should be evaluated as a contaminant of thetotal gamma-ray flux. Therefore, the moderator should be thick enough to absorb the gamma-rays
produced by the target. As shown in Figure 2, the model of the neutron-generating target at OKTAVIAN[11], in the authors’ laboratory, was simulated to examine the behavior of the gamma-rays emitted fromthe target. The layers of the neutron-generating target were 0.01 cm Ti + 0.1 cm Cu + 0.24 cm H2O + 0.1
cm stainless steel (304). 𝜂𝜂𝑡𝑡 is defined to evaluate the shielding ability of each material to absorb the
gamma-rays emitted from the target:𝜂𝜂𝑡𝑡 =

𝐹𝐹𝐺𝐺𝑡𝑡

𝐹𝐹𝐺𝐺𝑚𝑚+𝑚𝑚,(1)

where 𝐹𝐹𝐺𝐺𝑡𝑡 is the gamma-ray flux produced at the target, and 𝐹𝐹𝐺𝐺𝑡𝑡+𝑚𝑚 is the total gamma-ray flux. When- 104 104

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𝜂𝜂𝑡𝑡 reaches 0%, the contribution of gamma-rays produced at the target is removed theoretically. The
results of 𝜂𝜂𝑡𝑡 of Al, Fe, Pb, CF2, and AlF3 are shown in Figure 3. As the thickness increases, 𝜂𝜂𝑡𝑡 of Al,
Fe, Pb, CF2, and AlF3 declines and saturates at approximately 1%, 0%, 0%, 5%, and 3%, respectively.

19 cm Fe and 12 cm Pb were determined as a minimum thickness to remove the contribution of the
gamma-rays emitted from the target.

Figure 2. Schematic illustration of calculating gamma-ray flux.

Figure 3. Evaluation of contribution of gamma-rays produced at the neutron-generating target.
3. Results and discussion
3.1. Neutron and gamma-ray doses
The gamma-ray to neutron dose ratio 𝜂𝜂𝑑𝑑 is defined as:𝐷𝐷𝜂𝜂𝑑𝑑 = 𝐷𝐷𝛾𝛾 ,𝑛𝑛(2)where 𝐷𝐷𝛾𝛾 is the gamma-ray dose, and 𝐷𝐷𝑛𝑛 is the neutron dose. In this study, 𝜂𝜂𝑑𝑑 was controlled in

between 0% and 200% ( 𝐷𝐷𝛾𝛾 < 𝐷𝐷𝑛𝑛 𝐷𝐷𝛾𝛾 ≈ 𝐷𝐷𝑛𝑛 𝐷𝐷𝛾𝛾 > 𝐷𝐷𝑛𝑛 ). The combinations and thicknesses of themoderators were set to: Fe (19 cm) + PE (0-8 cm), PE (0-24 cm) + Fe (19 cm), Pb (12 cm) + PE (0-14cm), PE (0-47 cm) + Pb (12 cm), CF2 (42-60 cm), and AlF3 (47-65 cm). The results of 𝐷𝐷𝛾𝛾 , 𝐷𝐷𝑛𝑛 , and 𝜂𝜂𝑑𝑑
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are shown in Figure 4. In Figure 4 (a), 𝐷𝐷𝑛𝑛 is attenuated, as the thickness of the moderator increases. In
Figure 4 (b), 𝐷𝐷𝛾𝛾 is enhanced with the increasement of the thickness of PE, e.g., Fe (19 cm) + PE (0-7cm) and Pb (12 cm) + PE (1-10 cm). In Figure 4 (c), 𝜂𝜂𝑑𝑑 ascends rapidly and approaches 200%, byincreasing the thickness of PE. Because 1H(n,γ)2H reactions produce more gamma-rays [12], PE is aneffective material to increase 𝜂𝜂𝑑𝑑 . For CF2 (42-60 cm) and AlF3 (47-65 cm) as a single-material moderator,
𝜂𝜂𝑑𝑑 is below 80.5%.

Figure 4: (a) Neutron dose, 𝐷𝐷𝑛𝑛 ; (b) Gamma-ray dose, 𝐷𝐷𝛾𝛾 (c) Gamma-ray to neutron dose ratio, 𝜂𝜂𝑑𝑑 .
3.2. Mixed field of neutron and gamma-ray
Neutrons produced in the n-γ mixed field were divided into three energy groups: (i) fast (0.01-2.5
MeV), (ii) epi-thermal (5×10-7-0.01 MeV), and (iii) thermal (< 5×10-7 MeV) neutrons. Then the n-γ mixed
fields were classified into three types: (i) Fast (F) -dominant, (ii) Epithermal (E) -dominant, and (iii)
Thermal (T) -dominant fields.
3.2.1. F-dominant field
The results of F-dominant field are summarized in Table 1. 𝜂𝜂𝑑𝑑 ranges from 2.5% to 188.1%.
Because Fe has large cross-sections of (n,γ) reaction at thermal energy [12], PE + Fe is a suitable- 106 106

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combination to generate F-dominant fields, and PE (0-24 cm) + Fe (19 cm) provides: 𝜂𝜂𝑑𝑑 from 15.5 to

188.1%, proportion of fast neutron from 88.0% to 99.8%, and gamma-ray energy in 0-10.1 MeV.
Table 1. Characteristics of F-dominant fields
Material

Gamma-ray to neutron dose ratio,

Proportion ofGamma-ray energy,

𝜂𝜂𝑑𝑑

fast neutron

MeV

PE (0-8 cm) + Pb (12 cm)

2.5-3.2%

51.6-100.0%

0-7.3

Pb (12 cm) + PE (0-8 cm)

2.8-68.5%

48.5-100.0%

0-7.3

Fe (19 cm) + PE (0-4 cm)

15.5-100.9%

48.6-99.8%

0-10.1PE (0-24 cm) + Fe (19 cm)

15.5-188.1%

88.0-99.8%

0-10.1

3.2.2. E-dominant field
The results of E-dominant field are summarized in Table 2. 𝜂𝜂𝑑𝑑 ranges from 39.4% [CF2 (42 cm)]
to 80.5% [AlF 3 (65 cm)], and it is difficult to enhance 𝜂𝜂𝑑𝑑 by increasing the thickness of the material.
Besides, the contribution of the gamma-rays emitted from the target remained 5.6% and 3.2% on average
for CF2 (42-60 cm) and AlF 3 (47-65 cm), respectively.
Table 2. Characteristics of E-dominant fields
Material
CF2 (42-60 cm)
AlF3 (47-65 cm)

Gamma-ray to neutron dose ratio,𝜂𝜂𝑑𝑑

Proportion ofepithermal neutron

Gamma-ray energy,
MeV39.4-67.7%

54.4-72.8%

0-7.3

71.3-80.5%

56.0-80.6%

0-9.0

3.2.3. T-dominant field
The results of T-dominant field are summarized in Table 3. 𝜂𝜂𝑑𝑑 ranges from 5.9% to 195.1%.
Because Pb has large cross-sections of (γ,absorption) reaction [12], PE + Pb is a suitable combination to

suppress 𝜂𝜂𝑑𝑑 to generate T-dominant fields, and PE (13-47 cm) + Pb (12 cm) provides: 𝜂𝜂𝑑𝑑 from 3.8%

to 183.6%, proportion of thermal neutron from 49.4% to 66.6%, and gamma-ray energy in 0-6.1 MeV.
Table 3. Characteristics of T-dominant fields
Material

Gamma-ray to neutron dose ratio,𝜂𝜂𝑑𝑑

Proportion ofthermal neutron

Gamma-ray energy,
MeV

Pb (12 cm) + PE (12-14 cm)

143.7-195.1%

48.3-52.8%

0-6.8

Fe (19 cm) + PE (7-8 cm)

158.2-182.8%

49.4-54.6%

0-10.1

PE (13-47 cm) + Pb (12 cm)

3.8-183.6%

49.4-66.6%

0-6.1

3. Conclusion
In this study, various types of n-γ mixed fields were designed to provide standard n-γ mixed fields
for validation experiments of the material-filtered RPLGD for BNCT. To remove the contribution of the
gamma-rays emitted from the target, 19 cm Fe and 12 cm Pb were determined as a minimum thickness
to suppress 𝜂𝜂𝑡𝑡 to approximately 0%. PE was an effective material to adjust 𝜂𝜂𝑑𝑑 between 0% and 200%.

The material combinations to generate n-γ mixed fields were recommended: (i) PE (0-24 cm) + Fe (19- 107 107

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cm) for F-dominant fields; (ii) CF2 (42-60 cm) and AlF3 (47-65 cm) for E-dominant fields (𝜂𝜂𝑡𝑡 was notneglectable); and (iii) PE (13-47 cm) + Pb (12 cm) for T-dominant fields. These results indicate that themoderation method by using a D-D neutron source is feasible to generate standard reference n-γ mixed
fields for developing RPLGD for a p-Li neutron source based BNCT system.

Acknowledgements
This work was supported by China Scholarship Council (No.202106240024) and JSPS KAKENHI(No. JP19H02648).

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International Atomic Energy Agency. Current Status of Neutron Capture Therapy, IAEA -TECDOC-

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Kiyanagi Y, Sakurai Y, Kumada H, Tanaka H. Status of Accelerator-Based BNCT Projects

Worldwide. AIP Conference Proceedings 2160; 2019, vol.2160, no.05012, pp.1-9.
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International Atomic Energy Agency, Relative biological effectiveness in ion beam therapy. Vienna,

Austria: Technical Reports Series No. 461, 2008, pp. 9.
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scintillators coupled with a large area SiPM array for a fast neutron dose rate detector. Nuclear Instruments &Methods in Physics Research Section a-Accelerators Spectrometers Detectors and Associated Equipment.
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Lin YC, Roca A, Liu YH, Tsai PE, Nievaart S, Liu HM, Moss R, Chou WT, Jiang SH. The dosecomparison between the THOR and HFR epithermal neutron beams. Radiation Measurements. 2010; vol.45,
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Ogawara R, Kusumoto T, Kobayashi A, Konishi T, Hamano T, Kodaira S. Discrimination ofhydroxyl radical yields due to thermal neutrons, fast neutrons, and gamma rays in accelerator-based neutron
fields. Radiation Physics and Chemistry. 2020; vol.173, no.108889, pp.1-5.
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Horiike H, Murata I, Iida T, Yoshihashi S, Hoashi E, Kato I, Hashimoto N, Kuri S, Oshiro S. Liquid

Li based neutron source for BNCT and science application. Appl Radiat Isotopes. 2015; vol.106, pp.92 -94.
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Hiramatsu K, Yoshihashi S, Kusaka S, Sato F, Hoashi E, Murata I. Gamma-Ray Dose Measurementwith Radio-Photoluminescence Glass Dosimeter in Mixed Radiation Field for BNCT. Epj Web Conf. 2017;vol.153, no.04009, pp.1-9.
9.

X-5 Monte Carlo Team. MCNP - A General N-Particle Transport Code, Version 5. 2003, updated

2005. pp. 3-78.
10. Brown DA, Chadwick MB, Capote R, et al. ENDF/B-VIII.0: The 8th Major Release of the Nuclear
Reaction Data Library with CIELO-project Cross Sections, New Standards and Thermal Scattering Data. Nucl
Data Sheets. 2018; vol.148, pp.1-142.
11. K. Sumita, A.Takahashi, T. Iida, et al. Osaka University 14 MeV Intense Neutron Source for Fusion
Studies. (OKTAVIAN Program) Fusion Technology. 1981; 1: pp.675-680.
12. Evaluated Nuclear Data File (ENDF), Database Version of 2022-10-07. [Published: International
Atomic Energy, Agency. Available from: https://www-nds.iaea.org/exfor/endf.htm (accessed 2022-02-23).

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17.

Design investigation of pencil-beam epi-thermal neutron sourcefor validation of low-energy neutron spectrometer

Yu FUJIWARA*, Shingo TAMAKI, Sachie KUSAKA, Fuminobu SATO and Isao MURATA
Graduate School of Osaka University
2-1, Yamadaoka, Suita, Osaka, 565-0871, Japan*Email: fujiwara21@qr.see.eng.osaka-u.ac.jp

We have developed a spectrometer to measure the energy spectrum in the epi-thermal neutron region(0.5 eV~10 keV). Although the validation experiments of this spectrometer were carried out, there was adiscrepancy between the measured and simulated values so the effectiveness cannot be confirmed. We
considered that this discrepancy was attributed to neutron incidence from the side of the detector and it
was found that a pencil-beam neutron source was required to improve the measurement accuracy.
In this study, we tried to design the beam performance by introducing a "Pre-collimator" to the original
beam shaping assembly using Monte Carlo Simulation. Since the previous method could not simulate
beam-neutrons, i.e. neutrons generated in a very forward direction, a new method that is separating the
calculation into two stages was introduced. As a result, we succeeded in dramatically improving the errorof the MCNP calculation from 43% to 2% compared to the previous studies.
Based on this calculation method, design calculations were performed for the pre-collimator todetermine four parameters. As a result, the parameters of the pre-collimator were polyethylene as thematerial, 70 cm in thickness, 1.4 cm as the collimator hole diameter, and 300 cm as the distance from theassembly. Finally, the beam performance was confirmed by calculating the radial and horizontal flux
distributions. The results showed that the designed neutron source has excellent performance up to 40 cm
from the exit of the pre-collimator.

1. Introduction
Boron neutron capture therapy (BNCT) is attracting attention as a next-generation cancer treatment.
BNCT uses epi-thermal neutrons and it is possible to selectively treat only cancer cells. Using thisadvantage, it is expected to treat refractory cancers such as glioblastoma, and recurrent cancers [1].
Currently, developing an accelerator-based neutron source (ABNS) for BNCT is underway, andevaluating the characteristics of the neutron field generated by the accelerator is one of the issues [2].
One of the characteristics is the energy spectrum in the epi-thermal neutron region (0.5 eV ~ 10 keV). It
is necessary to assess treatment effects such as exposure dose. However, there is no accurate method tomeasure it.
We have been developing a new measurement method with a 3He position-sensitive proportional counter.
Figure 1 shows our position-sensitive proportional counter. Using this detector, signals about where
neutrons react with the 3He can be obtained [3]. 3He has a large (n,p) reaction cross-section at low energy- 109 109

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and as shown in figure 2, the cross-section is proportional to the neutron energy [4]. Therefore, lowenergy neutrons react in the shallow of the spectrometer, and high-energy neutrons are detected in the
deeper places of the spectrometer. As a result, we can measure the distribution of the positions where
neutrons react with 3He regarding the depth of the spectrometer. We define this information as “Depth
distribution, y (r).” Then, we calculate the response rate to monochromatic energy, which is regarded asa “response function, R.” The energy spectrum can be obtained based on the following equation (1);𝑦𝑦𝑖𝑖 = 𝑅𝑅𝑖𝑖,𝑗𝑗 ∙ 𝑥𝑥𝑗𝑗

  

(1)

𝑦𝑦𝑖𝑖 is the depth distribution, 𝑅𝑅𝑖𝑖,𝑗𝑗 is the response function, and 𝑥𝑥𝑗𝑗 is the energy spectrum. To solve
equation (1) is “spectrum unfolding,” and we apply Bayesian estimation as a method to solve [5].

We confirmed that this method could be used to measure the neutron energy spectrum from the thermal

region up to 1 keV [6]. Figure 3 shows the experimental system for the validation by Osawa et al.[6]Figure 4 shows the validation results. y (r) was obtained as shown in Figure 4 (a), and it was converted
to the energy spectrum was estimated. Compared to the simulation value (shown in figure 4 (b)), there
was a discrepancy and we concluded that the reason was the large influence of neutrons incident from theside surface of the detector. To correctly and accurately validate the spectrometer, a pencil-beam typelow-energy neutron source is necessary, and we carry the design in the present study.
Figure 1: Presently employed position sensitive proportional counter

Figure 3: Experimental system of the

Figure 2: (n, p) cross section of ³He [4]spectrometer validation [6]Figure 4: (a) Depth distribution measured in the previous research. (b) Comparisonof the experimentally obtained neutron energy spectrum and the calculated one. [6]- 110 110

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2. Methods
2.1. Improvement of calculation Method
Though an attempt to make a pre-collimator was carried out in a previous study, the beam characteristics
remained issues [8]. In the previous study, the entire calculation was conducted by SSW/SSR options in
MCNP5. The SSW/SSR option can be used to reduce the calculation time substantially for a complex
geometry very large system or system in which large particle attenuation is expected. The mechanism is
as follows; first, an SSW surface is defined at an exit of the epi-thermal column, and all the transport dataof neutrons passing through the exit surface are stored for all the neutron histories. Next, the neutron
information obtained by the SSW option is connected to the SSR surface at the entrance surface of thespectrometer (inside the collimator), and calculations between the right-hand side of the epi-thermalcolumn and spectrometer are carried out.
However, under certain conditions, this method has been found to have limitations. For instance, we
set a large space between the epi-thermal column and the spectrometer. In this case, only neutrons havingvery small emission angles at the epi-thermal column surface can reach and contribute to the spectrometer.
Figure 6 shows the energy spectrum of neutrons for various emission angles at the column surface. These
are made by the transport data stored by the SSW option. As shown in Figure 5, the epi-thermal neutron
spectrum in the very forward direction (cos θ > 0.99) cannot be reproduced well. If the calculation iscarried out by this stored transport data in SSW, few neutrons can reach the detector in the design
simulation depending on the distance between the epi-thermal column and pre-collimator. Therefore, we
employed the following two steps instead of the use of the SSW/SSR option.
Step 1: Calculate the energy and angular distributions of neutrons on the exit of the epi-thermal column.
Step 2: Set the source on the exit surface and carry out the neutron transport calculation through the precollimator to the spectrometer under the following source term conditions.
Ⅰ. Neutron energy distribution: Neutron energy spectrum calculated in Step 1.
Ⅱ. Emission angle distribution: Precisely calculated emission angle distribution.
Ⅲ. Set bias in the emission angle. To obtain accurate calculation results without underestimating thereaction rate, the optimum range of emission angle was determined by calculating the reaction rate with
3He in various emission angle.

Figure 5: Neutron spectrum at the exit of the epi-thermal column for various emission angles- 111 111

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2.2. Design Model
Figure 6 shows an image of the experimental system for the verification experiment of the present lowenergy neutron spectrometer. Compared to the experimental system in the previous study (figure 2), we
added a shielding material between the epi-thermal column and the spectrometer with a collimator. We
named it a "pre-collimator”. Then, we thought of the following four parameters in the design simulation,i.e., (1) material, (2) width, (3) hole diameter, and (4) distance to the epi-thermal column. As a simulation
code, MCNP5 [7] was employed. Also, we used JENDL-4.0 [4] as the nuclear data library for the design
calculations. In the design, we set three design goals for beam performance;
Ⅰ. "The ratio of neutrons detected as A component (𝐑𝐑 𝐀𝐀 ) should be 99% or higher"

Ⅱ. "The number of neutrons detected as the A component (𝐍𝐍𝐀𝐀 ) should be 10,000 counts or higher.
Ⅲ. “The ratio of neutrons detected as B component (𝐑𝐑 𝐁𝐁 ) should be 0.1% or lessIn this study, we categorize the neutron detected by the 3He counter into three categories, A, B, and C,

as shown in Figure 7.

Figure 6: Image of the experimental system

Figure 7: Three possible paths of neutron passing through the detector

Figure 8: Angular flux at the exit of
the epi-thermal column

Figure 9: Reaction Rate in the detector
with respect to emission angle- 112 112

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3. Results
3.1. Comparison with SSW/SSR
Figure 8 illustrates the angular flux distribution at the exit of the epi-thermal column calculated in
MCNP. Third-order Legendre polynomial approximations were performed from this data, and the very forward emitting neutrons are produced at the exit of the epi-thermal column with this equation. Using
this angular distribution and energy spectrum shown in figure 5, the design calculation was carried out.
Then, figure 9 shows the reaction rate at the detector for the emission angle under the following
conditions: (1) polyethylene, (2) 50 cm, (3) 2.5 cm, and (4) 100 cm. This result meant that while thereaction rate was underestimated in the condition that the emission angle was limited to very forward
only, gradually the neutrons no longer affect the reaction rate. In this study, the optimal emission angle
was determined the cos 𝜃𝜃 = 0.995. To demonstrate the validity of our proposed calculation method, theneutron flux as a function of the distance from the collimator exit was calculated in each case.
Typically, in the present result, the neutron flux intensity decreases smoothly as the distance from thesource increases. However, the SSW/SSR method shows an unexpected fluctuation in the intensity
distribution. This is because the amount of the accumulated transport data with the SSW option is limited,e.g., the number of histories accumulated is not so large compared to the one required in the connecting
calculation. Consequently, the reliability of the SSW/SSR method is questionable, especially in thepresent design case. More practically, we compared the results obtained by our method and the SSW/SSR
method for the number of particles reaching the detector and its statistical error with MCNP. While only
3.0 × 10² particles reached the detector assuming 10¹⁰ particles in SSW/SSR method, 3.3 × 10⁴
particles reached the detector for 10⁷ particles in our method. In addition, the statistical error of
MCNP calculations is significantly improved to approximately 2% compared to nearly 40% for
SSW/SSR. Therefore, this method was thought to be able to perform the current design calculations
accurately.

3.2. Pre-collimator design
Table 1 shows the designed four parameters and the performance, the values of 𝑅𝑅𝐴𝐴 , 𝑁𝑁𝐴𝐴 , and 𝑅𝑅𝐵𝐵 of the
pre-collimator [9]. The presently designed epi-thermal neutron beam met the design target Ⅰ and Ⅲ.

However, the design goal Ⅱ was not met. It would be possible to satisfy the condition by extending theirradiation time.

3.3. Beam performance
In order to investigate the performance of the designed beam, we calculated the horizontal flux
distribution from the pre-collimator exit and the radial distribution from the center of the pre-collimator.
Figure 11 illustrates the results. X in figure 11 (b) meant the distance from collimator. As for thehorizontal flux distribution, this neutron source has good beam performance with little reduction in therange from 10 cm behind the pre-collimator to 40 cm backyards. Sharp reduction by 10 cm behind thepre-collimator was considered that it was attributed to the cadmium sheet set at the exit of the pre collimator. From the radial flux distribution, the spread of neutron was found. This information should
be investigated by the experiment.

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Table 1: Design results and performance [9]Figure 10: Neutron fluxed as a function of
the distance from the exit of collimator

Figure 11: (a) Horizontal flux distribution (b) Radial flux distribution

4. Conclusion
We have designed a pencil-beam neutron source for the validation experiment of the low-energy neutron
spectrometer, especially in the epi-thermal neutron region. By installing a pre-collimator, we realized
reducing the effect of neutrons incident from the side surfaces of the detector to less than 1%. In the
future, we will conduct validation experiments using the designed neutron beam to demonstrate theeffectiveness of the new epi-thermal neutron spectrometer. Furthermore, we plan to apply the neutron
beam designed in this study to BNCT and a wide range of other fields.

References[1] Locher, G, L. Am. J. Roentgenol. Radium. Ther. 1936; 36: 1-13.
[2] I, Murata, et al. Plasma and Fusion Res. 2018; 13: 2501007.
[3] Fischer B. E. Nucl. Instrum. Meth. 1977; 141: 173-181.
[4] K. Shibata, et al. J. Nucl. Sci. Technol. 2011; 48(1): 1-30.
[5] I, Murata, H. Miyamaru. Nucl. Instrum. And Meth. Phys. Res. A. 2008; 589: 445-454[6] Y. Osawa. Master-Dissertation, Osaka University; 2017.
[7] X-5 Monte Carlo Team: MCNP-A General Monte Carlo N-Particle Transport Code, version 5; 2003.
[8] M. Tanoshita. Master-Dissertation, Osaka University; 2018.
[9] Y. Fujiwara, et al. Proceedings of the 37th Workshop on Radiation Detectors and Their Uses in

KEK; 2023: in-press.

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JAEA-Conf 2023-001

18. Estimation of the Total Angular Momentum ofResonances using Low-energy Gamma-rays in
181
Ta(n, γ)182Ta Reaction
Shiori KAWAMURA†1,2, Shunsuke ENDO1,2, Osamu IWAMOTO2, Nobuyuki IWAMOTO2,
Atsushi KIMURA2, Masaaki KITAGUCHI1, Shoji NAKAMURA2, Takuya OKUDAIRA1,2,
Gerard ROVIRA2, Hirohiko M SHIMIZU1, and Hiromoto YOSHIKAWA3
1

Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan
2
Nuclear Data Center, Nuclear Science and Engineering Center,
Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
3
Research Center for Nuclear Physics, Osaka University,
10-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan†

Email: kawamura@phi.phys.nagoya-u.ac.jp

Abstract
The total angular momentum, J, of resonances is one of the most important parametersin low energy nuclear reactions. In this study, J of resonances were estimated by taking theratios between low-energy gamma-rays in 181 Ta(n, γ)182 Ta reaction. This method is based on
the Spin-Memory Effect (SME), in which the spin information of the resonance state remains
in the lower levels. In this study, J of 17 resonances were estimated with good accuracy fromneutron capture reaction measurement at J-PARC MLF ANNRI. Furthermore, the difference
in intensity ratios between 270-keV and 403-keV gamma-rays due to J, SME, was confirmed,
even though it did not appear in the theoretical value of CCONE. This result suggests that
there are unknown transitions.

1

Introduction

A nucleus is a very complex system dominated by strong nucleon-nucleon interactions. In 1936,
the compound nuclei model was proposed by Bohr to explain phenomena in neutron capture reactions [1]. A nuclear reaction through the compound nuclei are often understood by a statisticalmodel, especially the Random Matrix Theory (RMT). According to RMT, the distributions ofneutron width and partial gamma width of resonances follow the Porter-Thomas distribution [2].
Verifying whether the partial gamma widths follow the Porter-Thomas distribution will give a
better understanding of what nuclides and what conditions RMT can be applied to. In order toexamine that, the total angular momentum, J = I ± 1/2 where I is the spin of a target nucleus,of s-wave resonances must be determined precisely.
Nuclear data libraries have been used in various fields such as reactor physics and nuclear
physics. Thus more accurate data has been required. However, experiments have been associatedwith difficulty in determining J in many resonances. Since gamma-ray transitions between
excited levels are limited by the law of conservation of the angular momentum, the J of theresonances could be directly determined from the primary gamma-ray transitions. However,

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JAEA-Conf 2023-001

in fact, the intensity of primary gamma-rays may be weak or absent in the spectrum of aresonance because of the Porter-Thomas fluctuation for partial gamma width. Therefore, thereis the potential for difficulty to identify the selected high-energy gamma-rays and to estimate Jof resonances.
Several methods have been proposed to estimate J of resonances from a gamma-ray spectrum
without using primary gamma-ray transitions [3–5]. A method was to compare the intensity
ratios of appropriately chosen pairs of low-energy transitions in the gamma-ray spectrum of aresonance [5]. This method is based on the Spin-Memory Effect (SME) proposed by Huizenga
and Vandenbosch [6]. SME means that the spin information of an initial resonance state remains, even if there are many intermediate excited levels in the cascade transitions. This effectappears as differences in low-energy gamma-ray spectrum. If a transition where SME exits isselected, the intensity ratio of two transitions can be grouped around two different average values
corresponding to J of resonances.
Olejniczak et al. [7] suggested that the larger spin difference between two excited levels
emitting low energy gamma-rays, stronger SME appears. They also indicated that the SME isstronger for nuclei closer to the atomic number of Z = 50, namely magic number. In this study,
J of resonances of 181 Ta (Z = 73) was estimated from the intensity ratio of 403-keV to 270-keV
gamma-rays, which are emitted from same spin but different parities, in the 181 Ta(n, γ)182 Ta
reaction. According to Olejniczak et al., SME is predicted to be weak because the atomic
number of Ta is far from the magic number and the spin difference between adopted levels is
small. Nevertheless, a difference of the intensity ratios was observed, and J of resonances of
181 Ta was estimated. The results were compared with Riehs et al. [8] and CCONE [9].

2Experiment

The experiment was performed with the time-of-flight (TOF) method at the Accurate Neutron–Nucleus Reaction Measurement Instrument (ANNRI) of the Material and Life Science Experimental Facility (MLF) in the Japan Proton Accelerator Research Complex (J-PARC) [10].
At ANNRI, a high-intensity pulsed neutron beam with 6-mm diameter and a Ge-detector arraycovering a large solid angle with high resolution were used. Metalic natural Ta sample withdimensions of 6 mm × 6 mm × 2 mm was set at a 21.5 m flight path.

3

Analysis

The resonance energy was taken from JENDL-5 [11], and the gamma-ray spectra from resonances were obtained by gating the TOF spectrum at each resonance. Figure 1 shows the TOF
spectrum of 181 Ta(n, γ)182 Ta reaction. The obtained gamma-ray spectrum in the low gammaray energy region of 4.28-eV resonance (751 µs in TOF) is shown in Figure 2. The backgroundwas determined with connecting both sides of the tail for the gamma-ray peak. The integral of
the entire peak minus the integral of the background was defined as net-counts. The value of J
was estimated from the ratio of the net-counts between the 270-keV and 403-keV gamma-rays.
The ratios of the net-counts between the 270-keV and 403-keV gamma-rays were defined as
R = Sb /Sa , where Sa and Sb are the net-counts of the 270-keV and 403-keV gamma-rays, respectively. The detection efficiency at 270-keV (403-keV) was defined as a (b ) and the intensity
as Ia (Ib ), the net-counts was expressed Sa = a · Ia (Sb = b · Ib ). Since the net-counts dependon the detection efficiencies for each gamma-ray energy, the absolute value of the intensity ratio,
R is affected by detection efficiency. However, since only the intensity ratios of two groups,
J = 3 and 4, defined as Q = R4 /R3 , where R4  and R3  are the weighted averages of the- 116 116

JAEA-Conf 2023-001

net-count ratios for the resonances estimated as J = 4 and 3, are considered in this analysis, acorrection for the detection efficiency was not required.

Figure 1: TOF spectrum measured with the metallic natural Ta sample. Many resonances wereobserved and labeled with the values of their energies taken from JENDL-5 [11].

Figure 2: The gamma-ray spectrum in the range of 100 keV to 600 keV emitted from 4.28-eV
resonance.

4

Results and Discussion

The ratios of the net-counts between the 270-keV and 403-keV gamma-rays, defined as R, areplotted for each resonance in Figure 3. The red line in Figure 3 indicates the average value of all
ratios. The average value R was 1.24 ± 0.01. The error in R results from the constant fittingof the ratios. The obtained ratios were clearly separated into two groups. We estimated J of
the resonance relative to the average value. This estimation was based on the result that J of
the 4.28-eV (10.36-eV) resonance was determined with good precision to be 4 (3) [13]. Table 1
displays the estimated J, compared with evaluated data of JENDL-5 and ENDF/B-VIII.0 andthe result of Riehs et al. [8]. Since the errors for 35.9-eV, 57.53-eV, 82.92-eV, and 91.4-eV
resonances crossed the average value, J of these resonances could not be fixed. The estimated
J was mostly consistent with the study of Riehs et al. [8] and JENDL-5 [11]. However, somedifferences with ENDF/B-VIII.0 [12] were observed. In this study, J of 17 resonances were
estimated with good statistical accuracy and suggestions were given for J of 4 resonances byusing the method based on SME.
The weighted averages of the resonances estimated as J = 4 and J = 3 were defined as
R4  and R3  and shown in Figure 3 with the blue and green lines, respectively. R4  =- 117 117

JAEA-Conf 2023-001

Table 1: Assignment of J for 181Ta+n resonances. Number in parenthesis represents theresults from the ratios whose error crosses the average value.
Resonance Energy
[eV]
4.28
10.33
13.83
20.29
22.72
23.93
30.03
34.21
35.14
35.91
39.12
49.11
57.53
59.05
63.10
76.84
77.61
78.89
82.89
85.10
85.60
89.58
91.38
96.95
99.27
103.5
105.5
115.0

JENDL-5 [11]
4
3
4
3
3
4
3
4
3
4
4
3
4
4
4
4
4
3
4
3
4
3
3
4
3
3
3
4

J
ENDF/B-VIII.0 [12]
4
3
4
4
3
3
4
3
4
3
4
3
4
3
4
3
4
3
4
3
4
4
4
3
4
3
4
3

Riehs et al. [8]
4
3
4
3
(3)
4
3

Present Work
4
3
4
3
4
4
3

3
4
4
3

3
(4)
4
3
(3)

4

4
4

4
(3)

4
(3)
4
(3)

3

3

3
4

3
4

1.32±0.01 and R3  = 1.12±0.01 were obtained. In order to compare the results with theoreticalvalues and to quantitatively describe the strength of SME, Q = R4 /R3  was used, andQ = 1.17 ± 0.01. Furthermore, expressing the ratio of difference |R4  − R3 | from their averagevalue (R4  + R3 )/2 in percentage, SME = 200|Q − 1|/(Q + 1) = 15.8% was obtained. This
SME value is small, compared to those (27%-32%) of Olejniczak et al. [7]. This may be ascribedto the small spin differences between transition levels. Despite the fact that 181 Ta is a nuclide
with Z = 73, whose atomic number is far from the magic number, and the gamma-rays of
270-keV and 403-keV are transited from the same spin state, a weak SME appears. This result
suggests that the SME appears regardless of the atomic number of the nuclide and the spin stateof the gamma-ray taking the intensity ratio.
It is interested in comparing the obtained results with the values calculated with a theoreticalmodel. In order to do this, the Hauser-Feshbach statistical model code CCONE was utilized [9].
In the CCONE code, excited level information was taken from RIPL-3 database and gamma-ray
strength functions were based on the generalized Lorentzian model for E1 radiation and theLorentzian model for M1 and E2 radiations. Excited states of J = 3 and 4 were generated close- 118 118

JAEA-Conf 2023-001

Figure 3: Ratios of the net-counts of 270-keV and 403-keV gamma-ray for each resonance. The
red line indicates the average value of all ratios. The weighted average values R4  and R3  ofJ = 4 and 3 are shown by blue and green lines, respectively.

Cross Section [mb/MeV]

to the neutron binding energy of 182 Ta. Gamma-ray decays from each J-state were calculated.
The resulting production cross sections of 403-keV and 270-keV gamma-rays were 23.9 and 42.7
mb for J = 3 and 15.3 and 27.5 mb for J = 4, respectively. The gamma-ray spectra in a
low gamma-ray energy region calculated with CCONE are shown in Figure 4. The ratio of
the 403-keV to 270-keV gamma-ray intensities was found to have the same value, 0.57 for bothJ. Therefore, theoretical results indicate no difference in these gamma-ray intensities. But
the clear difference was observed in the present experimental result. This fact suggests that
there are unknown transitions to reach the two excited levels which emit 270-keV and 403-keV
gamma-rays. In the CCONE calculation the upper excitation energy of 182 Ta was chosen to be
817 keV, above which missing levels and transitions increase. The number of adopted excitedlevels may be too small to follow complicated gamma-ray transitions. This result can help toconstruct a new validated level scheme.
Before concluding that SME of 182 Ta is weak, it is necessary to examine SME with the other
low-energy gamma-rays in 181 Ta(n, γ)182 Ta reaction. In addition, SME of the other nuclei farfrom magic number of Z = 50 should be examined with the same method.

250
200
150
100
50
0
100

150

200

250

300

350

400
450
500
Gamma-ray Energy [keV]

Figure 4: Gamma-ray spectra calculated with CCONE. The red and blue lines represent the
gamma-rays from J = 3 and J = 4 resonances.

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JAEA-Conf 2023-001

5Conclusion

In this study, we estimated J of 17 resonances with good accuracy and also gave suggestions
for J of 4 resonances up to 115 eV in 181 Ta(n, γ)182 Ta reaction using the ratio between 270-keV
and 403-keV gamma-ray intensities from resonances. The obtained intensity ratios differed fromtheoretical value of CCONE, and this fact suggested that there are unknown transitions. It isalso implied that SME appears independent of the atomic number and the spin state from which
the gamma-ray transitions occur. It is necessary to use other low-energy gamma-rays of 182 Ta
and use other nuclei to verify SME further. The estimated J in this study will be used to verify
whether the partial gamma width follows the Porter-Thomas distribution.

Acknowledgments
The authors would like to thank the staff for their efforts in operating the accelerators and theneutron production target of MLF in J-PARC. The neutron experiments at ANNRI of MLF in
J-PARC were performed under the project proposal (2022P0301).

References[1] Bohr N. Neutron Capture and Nuclear Constitution. Nature. 1936;137:344-348.
[2] Porter CE, Thomas RG. Fluctuations of Nuclear Reaction Widths. Phys Rev.
1956;104(2):483-491.
[3] Coceva C, Corvi F, Giacobbe P, Carraro G. A method of spin assignment of neutron
resonances based on capture gamma-ray detection. Nucl Phys A. 1968;117(3):586-614.
[4] Reddingius ER, Postma H, Olsen CE, et al. Spins of low-energy neutron resonances in 235 U.
Nucl Phys A. 1964;218(1):84-94.
[5] Wetzel KJ, Thomas GE. Method for Determining Spins of Neutron Resonances. Phys Rev
C. 1970;1(4):1501-1507.
[6] Huizenga JR, Vandenbosch R. Interpretation of Isomeric Cross-Section Ratios for (n, γ)and (γ, n) Reactions. Phys Rev. 1960;120(4):1305-1312.
[7] Olejniczak U, Gundorin NA, Pikelner LB, et al. Resonance-Spin Memory in Low-EnergyGamma-Ray Spectra from Sb, Tb, Ho, and Ta Odd–Odd Compound Nuclei. Phys. At.
Nucl. 2002;65(11):2044–2051.
[8] Riehs P, Axmann HP, Murray J, Thomas BW. Low-energy γ-rays from resonance neutron
capture in 181 Ta(n, γ)182 Ta. Nucl Phys A. 1972;198(2):430-438.
[9] Iwamoto O, Iwamoto N, Kunieda S, et al. The CCONE code system and its application to
nuclear data evaluation for fission and other reactions. Nuclear Data Sheets. 2016;131:259288.
[10] Igashira M. Kiyanagi Y. Oshima M. Nuclear data study at J-PARC BL04. Nucl Inst Meth
A. 2009;600(1):332-334.
[11] Iwamoto O, et al. Japanese Evaluated Nuclear Data Library version 5: JENDL-5. J. Nucl.
Sci. Technol. in press.
[12] Brown D, Chadwick M, Capote R, et al. ENDF/B-VIII.0:The 8th Major Release of the
Nuclear Reaction Data Library with CIELO-project Cross Sections, New Standards andThermal Scattering Data. Nuclear Data Sheets. 2018;148:1-142.
[13] Stolovy A. Spin Determinations of Neutron Resonances in Sb, Ta, Re, and Ir, Using IronAlloy Targets. Phys Rev. 1967;155(4):1330-1333.

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JAEA-Conf 2023-001

19. Theoretical study of low-excitation fission
phenomena in unstable thorium isotopes
Wataru Miyasakai1, Yoshihiro Aritomo1, and Shinya Takagi1
1

Faculty of Science and Engineering, Kindai University Higashi-Osaka, Osaka 577-8502,
Japan

Abstract
The production yields of fission fragments close to the β stable line cause asymmetricfission with peaks in the heavier and lighter nuclei, but away from the β stable line, fission
becomes symmetric. For example, at mass numbers near 226, Thorium (Th) exhibits both
symmetric and asymmetric fission [1]. The reason why the fission mode depends on the ratioof neutron to proton number has been investigated by various theoretical models. Even the
dynamical models, which have been very successful in the fission of neutron rich nuclei, haveso far not succeeded in describing symmetric fission phenomena in proton rich nuclei.
In this study, we use the dynamical model, which can successfully describe the fissionof Uraninm (U) and Plutonium (Pu) near the β stable line, to perform calculations for thefission of unstable nuclei away from the β stable line. Based on the results, we will propose
a solution policy for the future development and evolution of the model.

1

Introduction

The nucleus is a quantum many-body system consisting of a finite number of nucleons. The
various forms of existence and abundant modes of motion exhibited by this quantum many
body system have not yet been fully elucidated, and nuclear structure theory, for which model
improvements and new models have been proposed, focuses on the static and time-dependent
dynamical properties of nuclei. One of the most important research topics is the dynamics ofapproximate binding conditions of nucleon many body systems. In our laboratory, we havebeen studying nuclear reactions by following the time evolution of the shape of nuclei with adynamical model[2].
The dynamical model used in this study defines the shape of nuclei in terms of three parameters: the two center of distance z, the deformation degree δ, and the mass asymmetry α(two center shell model), and uses the Langevin equation, one of the equations of motion. The
Langevin equation follows the time evolution of each trajectory by ordinary differential equations based on the fluctuation dissipation theorem, and is able to reproduce the actual width offission phenomena from the dissipative fluctuation term.
Our previous studies have shown that the dynamical models we use in our theoretical calculations reproduce experimental data for stable fission, such as uranium (Z=92,U) and plutonium(Z=94,Pu), and contribute to the explanation of fission phenomena[1]. However, we cannot reproduce fission yields of experimental data for unstable nuclei[3]. The purpose of this study is toreveal the cause of this problem by analyzing the unstable nuclei thorium (Z=90,Th) in detail.

1- 121 121

JAEA-Conf 2023-001

2

Framework

We use the fluctuation-dissipation model and employ the Langevin equations[4] to investigate
the fission process. The nuclear shape is defined by the two center parametrization [5,6], which
has three deformation parameters, z, δ, and α to serve as collective coordinates: z is corresponds
to the distance between two potential centers, α is a mass-asymmetry parameter defined by (A1 A2 )/(A1 +A2 ) using fragment masses, A1 and A2 . The symbol δ denotes the deformation of thefragments defined as δ = 3(R − R⊥ )/(2R +R⊥ ), where R and R⊥ are the half length of theaxes of an ellipse in the z0 and ρ directions of the cylindrical coordinate, respectively, as shownin Figure 1 in Ref. [4].
We adopted the neck parameter ε=0.35 following the empirical relation in Ref. [3]. The threecollective coordinates are abbreviated as q, q = {z,δ,α}. For a given value of a temperature ofa system T , the potential energy is defined as a sum of the liquid-drop (LD) part, a rotationalenergy and a microscopic (SH) part:2 l(l + 1)
+ VSH (q, T ),2I(q)VLD (q) = Es (q) + Ec (q),V (q, l, T ) = VLD (q) +0(q)Φ(T ),VSH (q, T ) = Eshell


aT 2

Φ(T ) = exp −

Ed

,

(1)
(2)
(3)
(4)

Here, VLD is the potential energy calculated with the finite range liquid drop model, given
as a sum of the surface energy ES [6] and the Coulomb energy EC . VSH is the shell correctionenergy evaluated by the Strutinski method from the single-particle levels of the two center shellmodel. The shell correction has a temperature dependence expressed by a factor Φ(T), in which
Ed is the shell damping energy chosen to be 20 MeV [7] and a is the level density parameter.
At the zero temperature (T = 0), the shell correction energy reduces to that of the two center0
shell model values Eshell. The second term on the right hand side of Eq. (1)is the rotationalenergy for an angular momentum l [4], with a moment of inertia at q, I(q).
The multidimensional Langevin equations [4] are given as
dqi  −1 
= m ij pi ,dt1 ∂  −1 
dpi
∂V
=−
−
m jk pj pk − γij m−1 jk pk + gij Rj (t)
dt
∂qi
2 ∂qi

(5)
(6)

where i ={z,δ,α} and pi is a momentum conjugate to coordinate qi . The summation is performed over repeated indices. In the Langevin equation, mij and γij are the shape-dependent
collective inertia and the friction tensors, respectively. The wall-and-window one-body dissipation [8-10] is adopted for the friction tensor which can describe the pre-scission neutron
multiplicities and total kinetic energy of fragments simultaneously [11]. A hydrodynamical
inertia tensor is adopted with the Werner-Wheeler approximation for the velocity field [12].
The normalized random force Ri (t) is assumed to be that of white noise, i.e., 〈Ri (t)〉=0 and〈Ri (t1 )Rj (t2 )〉=2δ
ij δ(t1 − t2 ). The strength of the random force gij is given by the Einstein
relation γij T = k gij gjk

3

Results

In the current situation, as a cause of the strong asymmetric fission, we have explained thefission phenomena by confirming the dynamical trajectories and potential structures of 226 Th- 122 122

JAEA-Conf 2023-001

nuclides. By looking at the structure of the z-α plane potential in the 226 Th calculated inthis study as well, we are able to infer some fission phenomena. Figure 1 shows the z-α planepotentials for δ = -0.02, 0.22, and 0.40. When the deformation δ is -0.02, an asymmetric fission
valley appears in the direction of the arrow. In other words, if the nucleus is spherical, it causes
asymmetric fission, which means that most of the fission trajectories split in a spherical shapein the case of low excitation fission. In addition, when the deformations δ are 0.22 and 0.40,
symmetric fission valleys appear, which fission in the direction of the arrow. In other words,
fission in the deformed state of the nucleus is symmetric fission.

𝛿𝛿 = 0.22𝛿𝛿 = 0.40

Ｖ[MeV]𝛼𝛼𝛿𝛿 = −0.02

𝑧𝑧

Figure 1: Comparison of z-α plane potentials at 226 Th for δ = −0.02, 0.22, 0.40
In the dynamical model calculations, we examined whether the transition between symmetricand asymmetric fission is caused by these features by increasing the initial value of δ0 . By
increasing the deformation δ0 of the compound nucleus, at a certain point we obtain a trajectoryin which the nucleus fissions in a deformed state. Figure 2 shows the results of increasing thedeformation δ0 . This result confirms that symmetric fission occurs at high deformation, i.e., thestructure of the potential plane in Figure 1 determines to some extent the fission event.

4

Conclusion

In this study, low excitation fission of 226 Th of nuclides far from β stable line, which experimentally shows the transition between symmetric and asymmetric fission, is calculated withthe dynamical model currently being developed to reproduce symmetric fission for proton-richnuclei, and we analyze to clarify the reason why symmetric fission is not observerd. The resultsof the present analysis show that the dynamics model is the most suitable for the present study.
From the results of this analysis, the reason why symmetric fission phenomena cannot be represented, which is the problem of the dynamical model, is that the z-α plane potential in theabsence of deformation has only a structure that causes asymmetric fission, and that two fission
fragments split in a spherical shape at fission, in other words, they split without any deformation.

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JAEA-Conf 2023-001

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㻣㻜

㻤㻜

0DVV>0H9@㻥㻜㻝㻜㻜 㻝㻝㻜 㻝㻞㻜 㻝㻟㻜 㻝㻠㻜 㻝㻡㻜 㻝㻢㻜 㻝㻣㻜 㻝㻤㻜

Figure 2: Comparison of mass distribution at 226 Th (E ∗ =15MeV), at two center distancez=0.65,1.00 with deformation δ0 =0.30-0.60 and mass asymmetry α0 0.05

To solve this problem, we can increase the probability of increasing deformation by making the
dynamical model independent[13], in which the two fragments have the same deformation (onemore degree of freedom in deformation), to reproduce symmetric fission (fission in the shape
shown on the left in Figure 3), or by using a different model for the nuclear structure (potential
plane). Alternatively, it is necessary to develop a model that describes a potential structure inwhich symmetric and asymmetric fission of proton-rich nuclei exist simultaneously by using a
different model for the nuclear structure (potential plane) or symmetric fission (fission in the
shape shown on the right in Figure 3).

Figure 3: Nuclear shapes at 226 Th, the left figure shows the shape of the nucleus when fissioned
symmetrically in a spherical shape, and the right figure shows the shape of the nucleus whenfissioned in a deformed state as seen in the dynamical model.

References[1] K-H Schimidt, J Benlliure and A. R. Junghans Nuclear Physics A 693, 169 189(2001).
[2] Y.Aritomo and S.Chiba, Physical Review C 88, 044614 (2013).
[3] Y. Miyamoto et al., Phys. Rev. C, 99, 051601(R) (2019).
[4] Y. Aritomo and M. Ohta, Nucl. Phys. A 744, 3 (2004).
[5] K. Sato, A. Iwamoto, K. Harada, S. Yamaji, and S. Yoshida,Z. Phys. A 288, 383 (1978).

- 124
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JAEA-Conf 2023-001[6] H. J. Krappe, J. R. Nix, and A. J. Sierk, Phys. Rev. C 20, 992(1979).
[7] A. V. Ignatyuk, G. N. Smirenkin, and A. S. Tishin, Sov. J. Nucl. Phys. 21, 255 (1975).
[8] J. Blocki, Y. Boneh, J. R. Nix, J. Randrup, M. Robel, A. J. Sierk, and W. J. Swiatecki, Ann.
Phys. 113, 330 (1978).
[9] J. R. Nix and A. J. Sierk, Nucl. Phys. A 428, 161c (1984).
[10] H. Feldmeier, Rep. Prog. Phys. 50, 915 (1987).
[11] T.Wada,Y.Abe, and N. Carjen,Phys. Rev. Lett. 70, 3538 (1993).
[12] K. T. R. Davies, A. J. Sierk, and J. R. Nix, Phys. Rev. C 13, 2385 (1976).
[13] C. Ishizuka, M. D. Usang, F. A. Ivanyuk, J. A. Maruhn, K. Nishio, and S. Chiba, PhysicalReview C, 96(6), 064616 (2017).

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JAEA-Conf 2023-001

20.

Theoretical estimation of synthesizing neutron richnuclei in superheavy mass region

S. Nishikawa Y. Aritomo, S. Takagi, H. Maekawa, S. Amano, K. Shibata, A. Asami
Faculty of Science and Engineering, Kindai University
3-4-1 Kowakae, Higashiosaka City, Osaka 577-8502, Japan

1. Introduction and BackgroundThe next double magic nucleus after the double magic nucleus lead (208Pb) proton number Z=82
and neutron number N=126 is predicted to be flerovium 298Fl, Z=114 and N=184, and the "islandof stability " around this nucleus is predicted in the nuclear chart. In the synthesis of new elements,
it was assumed that the incident and target nuclei used in experiments would be stable nuclei. In
particular, it was experimentally impossible to use unstable nuclei as target nuclei. Therefore, it
was considered difficult to synthesize nuclei on the island of stability because of the insufficientnumber of neutrons when it came to fusion between stable nuclei. In order to synthesize nuclei
around the island of stability, it is necessary to fuse unstable nuclei with an excess of neutrons,
but until now there has been no method to achieve this. Recently, however, a new method forcolliding unstable nuclei has been devised. This new method is called RUNBA [1]. Using
RUNBA, a method to synthesize nuclei located in the island of stability has been developed, and
it is expected to clarify whether or not the island of stability exists. If nuclei on the islands ofstability can be synthesized and fundamental physical quantities such as lifetime and mass can be
determined, this will provide important data for constructing and verifying the ultimate nuclear
theory. The goal of this study is to investigate and evaluate the evaporation residue nucleus crosssection of a reaction system in which our theoretical calculations using the dynamical model
synthesize the island of stability nuclei with unstable nuclei, now that the RUNBA project isunderway.
To calculate the evaporation residue cross sections for neutron-rich nuclei, we need to calculate
the survival probability. The survival probability is calculated and evaluated using a statisticalmodel. At that time, an error occurred in the statistical model. Currently, the calculation is basedon the mass table by P. Moller et al [2], but we found that a problem occurs in the superheavy
mass and neutron rich region. In the present work, we have improved the code and mass table toapply the statistical model. We will further analyze the parameters in the code for the calculationand make improvements.

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JAEA-Conf 2023-001

7KHRU\DQG0HWKRG
There are several ways to parameterize the shape of the amalgamated system. This two-centerparameterization [3] is based on three important parameters are: the distance between two centersz, the mass-asymmetry parameter α, and the neck parameter ε. The dimensionless parameter z isdefined as follows,
𝑧𝑧 =

𝑧𝑧0
𝐵𝐵𝐵𝐵𝐶𝐶𝐶𝐶(1)

where zo denotes the distance between two centers of the potentials, and RCN is the radius of thespherical compound nucleus. B define as 𝐵𝐵 = (3 + 𝛿𝛿)/(3 − 2𝛿𝛿).

Fig. 1 Nuclear shape the two-center parametrization.
The mass-asymmetry parameter is defined as usual,
𝐴𝐴 −𝐴𝐴𝛼𝛼 = 𝐴𝐴1 +𝐴𝐴2
1

2

(2)

The Langevin equation uses potential energy, friction coefficient, and mass of inertia to derive
the probability 𝑃𝑃𝐶𝐶𝐶𝐶 . When the Langevin equation is solved for a large number of trajectories fromthe coordinates of the contact point, the majority of trajectories go straight down the potential

slope to quasi-fission. However, a very small number of trajectories overcome the potential barrier

due to fluctuations caused by random forces and reach the compound nuclear region. The
probability of not causing quasi-fission, 𝑃𝑃𝐶𝐶𝐶𝐶 , can be estimated by solving the Langevin equation

many times and calculating what percentage of all trajectories will reach the fusion region. In thisstudy, the multidimensional Langevin equation is used.[4]127- 127 -

JAEA-Conf 2023-001

𝑠𝑠𝑞𝑞𝑖𝑖= (𝑚𝑚−1 )𝑖𝑖𝑖𝑖 𝑝𝑝𝑖𝑖
𝑠𝑠𝑠𝑠

(3)

𝜕𝜕𝜕𝜕
1 𝜕𝜕
𝑠𝑠𝑝𝑝𝑖𝑖(𝑚𝑚−1 )𝑖𝑖𝑘𝑘 𝑝𝑝𝑖𝑖 𝑝𝑝𝑘𝑘 − 𝛾𝛾𝑖𝑖𝑖𝑖 (𝑚𝑚−1 )𝑖𝑖𝑘𝑘 𝑝𝑝𝑘𝑘 + 𝑔𝑔𝑖𝑖𝑖𝑖 𝑅𝑅𝑖𝑖 (𝑠𝑠)
= −
−
𝑠𝑠𝑠𝑠
𝜕𝜕𝑞𝑞𝑖𝑖 2 𝜕𝜕𝑞𝑞𝑖𝑖

where 𝑞𝑞𝑖𝑖 is deformation coordinate and 𝑝𝑝𝑖𝑖 is momentum of 𝑞𝑞𝑖𝑖 . V is also the potential, and𝑚𝑚𝑖𝑖𝑖𝑖 and 𝛾𝛾𝑖𝑖𝑖𝑖 are the inertial mass and friction coefficient, R(t) represents a random force

fluctuation, and 𝑔𝑔𝑖𝑖𝑖𝑖 is the strength of the random force. The shape of the nucleus ( 𝑞𝑞𝑖𝑖 ) was

determined by the two-center parameterization using three variables: 𝑧𝑧0 , which corresponds tothe distance between the centers of distance; δ, the degree of deformation of the left and rightfragments; and α, the degree of mass asymmetry.

The third stage is a decay process. In this stage, it is important to know the survival probability
𝑃𝑃𝑠𝑠𝑠𝑠𝑠𝑠 and it can be calculated by statistical model [5],
Γ

(𝑖𝑖)

𝑛𝑛
𝑃𝑃𝑠𝑠𝑠𝑠𝑠𝑠 = ∏𝐶𝐶𝑖𝑖=1 (𝑖𝑖) (𝑖𝑖)

Γ𝑛𝑛 +Γ𝑓𝑓(4).

𝛤𝛤𝑛𝑛 and 𝛤𝛤𝑓𝑓 are neutron evaporation width and fission decay width, respectively. From all the
probabilities in these 3 stages, we obtain the evaporation residue cross sections 𝜎𝜎𝐸𝐸𝐵𝐵
𝜎𝜎𝐸𝐸𝐵𝐵 =𝜋𝜋ℏ22µ0 𝐸𝐸𝑐𝑐𝑐𝑐∗∗∑∞
𝑙𝑙=0(2𝑙𝑙 + 1) 𝑇𝑇𝑙𝑙 (𝐸𝐸𝑐𝑐𝑐𝑐 , 𝑙𝑙)𝑃𝑃𝐶𝐶𝐶𝐶 (𝐸𝐸 , 𝑙𝑙)𝑃𝑃𝑠𝑠𝑠𝑠𝑠𝑠 (𝐸𝐸 , 𝑙𝑙) (5).

Ecm and E* denote to the incident energy and excitation energy while µ0 and l are reduced massin the entrance channel and angular momentum, respectively.
To calculate 𝜎𝜎𝐸𝐸𝐵𝐵 , there are some uncertain parameters in the model in each stage. Here, we
focus on the uncertainty in the third stage. In the equation (4) to obtain the survival probability[5], Γ𝑛𝑛 ⁄Γ𝑓𝑓 is calculated as follows,𝛤𝛤𝑛𝑛𝑘𝑘𝑐𝑐𝑐𝑐𝑙𝑙𝑙𝑙 (𝑔𝑔𝑔𝑔. 𝑠𝑠𝑠𝑠. )=𝐴𝐴0 𝑠𝑠𝑒𝑒𝑝𝑝 [2√𝑠𝑠𝑛𝑛 𝐸𝐸𝑛𝑛∗ − 2√𝑠𝑠𝑓𝑓 𝐸𝐸𝑓𝑓∗ ]𝛤𝛤𝑓𝑓 𝑘𝑘 (𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑙𝑙𝑠𝑠)・𝑘𝑘
𝑐𝑐𝑐𝑐𝑙𝑙𝑙𝑙

𝑘𝑘𝑠𝑠𝑘𝑘𝑐𝑐𝑘𝑘𝑠𝑠𝑠𝑠

𝐸𝐸𝑛𝑛∗ = 𝐸𝐸𝑖𝑖𝑛𝑛𝑖𝑖 − 𝐵𝐵𝑛𝑛
𝑘𝑘𝑘𝑘𝑠𝑠𝑘𝑘𝑐𝑐𝑘𝑘𝑠𝑠𝑠𝑠 =

,

ħ𝜔𝜔1

√𝐸𝐸𝑖𝑖𝑛𝑛𝑖𝑖

𝐸𝐸𝑓𝑓∗ = 𝐸𝐸𝑖𝑖𝑛𝑛𝑖𝑖 − 𝐵𝐵𝑓𝑓(√1 + 𝑒𝑒 2 − 𝑒𝑒)𝑒𝑒 ≡ 𝛾𝛾⁄2 𝜔𝜔1

𝑘𝑘𝑐𝑐𝑐𝑐𝑙𝑙𝑙𝑙 (𝛽𝛽2 ) =𝑇𝑇
𝐽𝐽 ≡ 𝜎𝜎⊥2
ħ2

45 2
5
𝐽𝐽 = 𝐽𝐽0 [1 + √
𝛽𝛽2 +
𝛽𝛽 ]
28𝜋𝜋 2
16𝜋𝜋

- 128
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(6).

JAEA-Conf 2023-001

22
𝐽𝐽0 = 𝐴𝐴𝑚𝑚𝑅𝑅𝑐𝑐𝑛𝑛
5∗) = (𝜎𝜎⊥2 − 1)𝑔𝑔(𝛽𝛽2 ) + 1 𝑓𝑓𝑓𝑓𝑔𝑔 𝜎𝜎⊥2 > 1
𝑘𝑘𝑐𝑐𝑐𝑐𝑙𝑙𝑙𝑙 (𝛽𝛽2 , 𝐸𝐸𝑖𝑖𝑛𝑛𝑖𝑖

𝑔𝑔(𝛽𝛽2 ) = [1 + exp ((0.15 − 𝛽𝛽2 ⁄∆𝛽𝛽2 )]−1(7)Here, 𝐵𝐵𝑛𝑛 is neutron separation energy. The uncertain parameters include fission barrier heightδBf, friction parameter γ and level density parameter a𝑓𝑓⁄a𝑛𝑛 in eq.(6). In the superheavy mass

region, it is no determined which values to be used. We need to know the parameter dependenceof the survival probability and to see how these uncertainties influence the survival probability

and evaporation residue cross section The collective enhancement factor kcoll can be expressed as afunction of the quadrupole deformation parameter β2.

5HVXOWDQG'LVFXVVLRQ
In our studies so far, we used the mass table by P. Moller [2]. In this study, however, we created
our own mass table, which is named as shiba.dat.
First, we prepared the potential energy surface (map) in two-center shell model and searched theposition at the ground state. The shape of its ground state should be taken as the lowest value on
the potential energy map around the spherical region, as Moller's table did. However, if the lowest
points are selected automatically, the position may jump, sometime. Moller's table shows such atendency, for example, Z =112, N=194-195. This is thought to be the cause of the abnormal value
in the calculation of the survival probability.
In the decay process of the compound nuclei, the position of the ground state is not significantly
different among isotopes, that are continuously transferred by neutron emission from thecompound nucleus. To search the position of the ground states using the potential energy map,
we choose the position of the ground state, which does not change significantly between isotopes.
By this method, we create the mass table, shiba.dat. Using this mass table, we calculated thesurvival probability and the evaporation residue cross section, which are shown in Figs 2 and 3.
The results confirm the improvement in survival probability and evaporation residue cross section.

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JAEA-Conf 2023-001

48Ca+260U→308Cn

48Ca+260U→308Cn

101

Evaporation Residue Cross Section (mb)

101

10-3

Survival Probability

10-7
10-11
10-15
10-19
10-23

β２=0.3β２=dbeta
β２=0

10-27
10-31
10-35

10

20

30

40

50

60

70

80

10-3
10-7
10-11
10-15
10-19
10-23

β２=0.3β２=dbeta
β２=0

10-27
10-31
10-35

90 100 110

10

20

30

40

E*(MeV)

50

60

70

80

90 100 110

E*(MeV)

Fig.2 The evaporation residue cross section and survival probability for 48Ca+260U→308Cn by
P.Moller`s mass table. (dbeta is P.Moller`s mass table)
48Ca+260U→308Cn

48Ca+260U→308Cn

101

10-3

Survival Probability

10-7
10-11
10-15
10-19
10-23

β２=dbeta
β２=dbetashiba

10-27

10-3
10-7
10-11
10-15
10-19
10-23

β２=dbeta
β２=dbetashiba

10-27
10-31

10-31
10-35

Evaporation Residue Cross Section (mb)

101

10

20

30

40

50

60

70

80

90 100 110

10-35

10

20

30

40

50

60

70

80

90 100 110

E*(MeV)E*(MeV)

Fig.3 The evaporation residue cross section and survival probability for 48Ca+260U→308Cn
by shiba.dat (dbetashiba is shiba.dat)

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JAEA-Conf 2023-001

We changed the upper limit of neutron emission from 10 times to 20 times in our calculations.
Next, 286Cn, we fixed at neutron separation energy (sep1 = 4.87) and β2 was varied in Fig.4.
β2= +22 is the result of calculating 286Cn to match 308Cn. The results confirm the improvement insurvival probability. For fixed β2= 0.22, the survival probability was found to be abnormal. When
fixed to β2= 0, the survival probability showed improvement. When β2 of collective enhancement
is fixed at 0.22 and β2 = 0, the survival probability is confirmed to be abnormal. Four results
indicate the possible impact of collective enhancement.

286

Cn do20 β2＝＋22sep1=4.87
Cn do20β2＝0.22(固）sep1=4.87（固）Cn do20β2＝0.0(固)sep1=4.87(固）286
Cn do20β2＝0.0（固）sep1=4.87(固）コレクティブエンハンスメントのβ2＝0.22（固）
286

10

1

101

308

Cn do10
Cn do20286
Cn do20
308

-3

10-3

10-7

Survival Probability W

Survival Probability W

10

10-11
10-15
10-19
10-23

10-7
10-11
10-15
10-19
10-23

10-27

10-27

shell=3.0
shiba.dat

10-31
10-35

286

10

20

30

40

shell=3.0
shiba.dat

10-31

50

60

70

80

10-35

90 100 110

10

*

20

30

40

50

60

70

80

90 100 110

E*(MeV)E (MeV)

Fig.4 The calculation results of survival probability for 48Ca+260U→308Cn , 48Ca+238U→286Cn(308Cn do10 means 10 times the upper limit of the number of neutrons in 308Cn. 
Cn do20 means 20 times the upper limit of the number of neutrons in 286Cn.)

286

The anomaly in survival probability is the effect of collective enhancement. In the code, we use
the mass table by P. Moller [2], and there are cases where the shell correction energies at the
ground state in neutron-rich nuclei are close to zero or even positive. Based on these analysis, we
discuss based on these analyses, and discuss the introduction of a dynamical model and themodification of the mass table as solutions to the problem.

5HIHUHQFHV[1] RIKEN NEWS 2019 September No.459, pp. 6.
[2] P.Moller et. al., Atomic Data and Nuclear Data Tables 109-110 (2016) 1-204.
[3] J. Maruhn, W. Greiner, Z. Phys. 251 (1972) 431.
[4] Yoshihiro Aritomo, Masahisa Ohta, Nuclear Physics A 744 (2004) 3–14
[5] M.Ohta, Proc. Of Fusion Dynamics at the Extremes,100(2001)

131- 131 -

JAEA-Conf 2023-001

21. Fission fragment yields of neutron-rich nuclei
evaluated by the Langevin model calculation
Shoya TANAKA†1 , Nobuya NISHIMURA1,2 , and Futoshi MINATO3
1

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

3

Astrophysical Big Bang Laboratory, CPR, RIKEN, Saitama 351-0198, Japan
Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Tokai, Ibaraki
319-1195, Japan†
Email: shoya.tanaka@riken.jp

Abstract
Nucleosynthesis by the rapid neutron-capture process (r-process) produces elements heavier than iron via neutron-rich nuclides, observed in the solar system and stars with various
metallicities. In the r-process, fission plays a fundamental role through bridging heavy element abundances with light element ones and by shaping the final r-abundance distribution.
Nevertheless, due to the difficulty of experimental approaches, most of the fission data available for r-process calculations are based on theoretical predictions with phenomenologicalmodels. In this study, we focused on the transition of fission mode from asymmetric to symmetric in neutron-rich isotopes, which has been suggested in recent experiments for fermium
isotopes. We investigated the fission of neutron-rich nuclei by a theoretical calculation basedon the dynamical model and employed Langevin equations. Furthermore, we calculated fission fragment mass yields and prompt neutron emissions by combining Langevin calculations
with a statistical model.

1

Introduction

Nucleosynthesis by the rapid-neutron-capture process, the so-called r-process, represents forcosmic origin of the heaviest elements (e.g., gold and uranium) beyond the iron-group peak.
Although several astrophysical scenarios that bring about the r-process have been proposed, themechanism itself is not completely understood (for a recent review, see [1, 2, 3]. One of the main
reasons is large uncertainties arising from the nuclear-physics properties of very neutron-rich nuclei, e.g., neutron capture rates and decay half-lives. To determine nucleosynthesis flows on the
r-process  path , the β-decay and the neutron capture (strongly depending on theoretical mass
prediction) are significant. Nuclear fission plays a key role of the termination of r-process path
toward heavier elements if the r-process flow is strong enough to reach actinides or transactinides. Nuclear fission, therefore, plays an essential role under certain r-process environmental
conditions [4, 5, 6, 7], in particular, in very neutron-rich environments, e.g., neutron star mergers, where the nucleosynthesis path is able to go into the very neutron-rich trans-uranium region.
The effects of fission are also significant to shape the r-process abundances due to the fission
recycling in which fission products become seed nuclei (A < 200) for the next r-processing
during a single nucleosynthesis process. Besides those effects, fission also has a key role as theheating source of kilonovae at late times (∼ 10 days to months), of electromagnetic transients of- 132 132

JAEA-Conf 2023-001

neutron star mergers [8, 9]. A sign of fission heating may have been observed in the light curveof the kilonova associated with the gravitational wave, GW170817. The precise understandingof fission becomes much crucial in the era of gravitational astronomy.
Fission product distributions are important for the r-process, but experimental data are notavailable in the neutron-rich region. From this respect, we calculated in this study the fission
fragment mass distributions (FFMDs) of very neutron-rich nuclei. We adopt the Langevinmethod [10], widely adopted in the study of low-energy fission. In addition, we have combined
Langevin calculations with a statistical model implemented in CCONE code [11] that calculatesparticle evaporation from highly nuclear excited states to estimate post-neutron emission fission
product yields. This approach is a more realistic treatment than conventional methods.

2

Model

We use the fluctuation-dissipation model and employ Langevin equations to calculate the evolution of nuclear shape with time [12, 13]. The nuclear shape is defined by the two-centerparametrization [14, 15], which has three deformation parameters, z, δ and α to serve as collective coordinates, abbreviated as q = {z, δ, α}. The symbol z is the distance between two potential
centers, the symbol δ denotes the deformation of the fragments, and α = (A1 − A2 )/(A1 + A2 )is the mass asymmetry of the two fragments [12], where A1 and A2 denote the mass numbers ofheavy and light fragments.
For a given value of the temperature of a system T , the potential energy is defined as a sumof the liquid-drop (LD) part and a microscopic (SH) part:V (q, T ) = VLD (q) + VSH (q, T ),(1)

VLD (q) = ES (q) + EC (q),(2)

VSH (q, T ) = [∆Eshell (q) + ∆Epair (q)]Φ(T ),(3)Φ(T ) = exp −

aT 2
Ed



.

(4)

Here, the potential energy VLD is calculated with the finite-range liquid drop model [16], given
as a sum of the surface energy ES and the Coulomb energy EC . The microscopic energy VSH at
T = 0 is calculated as the sum of the shell correction energy ∆Eshell , evaluated by the Strutinski
method [17, 18], and the pairing correlation correction energy ∆Epair [19]. The shell correctionenergy has a temperature dependence expressed by a factor Φ(T ) in which the shell damping
energy Ed is chosen as 20 MeV [20] and a is the level density parameter [13, 21]. To define
the potential of the two-center shell model a neck parameter of  = 0.35 (0 ≤  ≤ 1) has been
regularly used. However, this value is not appropriate for heavier actinide nuclides as pointed
out in [22, 23]. To reproduce the experimental data, the value was systematically increased withthe mass of fissioning nuclides. A calculation was performed to determine the optimal values
leading to the best agreement with each FFMD. We adopt the optimal  values following theempirical relation
(Ac ) = 0.01007Ac − 1.94,(5)where Ac is the mass of the fissioning nuclide.
The multidimensional Langevin equations [12] are given asdqi= (m−1 )ij pj ,dt

- 133 133

(6)

JAEA-Conf 2023-001

∂V
1 ∂
dpi
=−
−
(m−1 )jk pj pk − γij (m−1 )jk pk + gij Rj (t),
dt
∂qi
2 ∂qi

(7)

where qi = {z, δ, α} and pi = mij dqi /dt is a momentum conjugate to coordinate qi . In theLangevin equation, mij and γij are the shape-dependent collective inertia and the friction tensors, respectively. The wall-and-window one-body dissipation [24, 25, 26] is adopted for thefriction tensor. The normalized random force Ri (t) is assumed to be that of white noise, i.e.,Ri (t) = 0, Ri (ti )Rj (t2 ) = 2δij δ(t1 − t2 ).

(8)

The strength of the random force gij is related to the friction tensor γij by the classical Einstain
relation,
gik gjk = γij T.
(9)k

We calculated the charge distribution based on the unchanged charge distribution (UCD) assumption. The charge distribution (charge density) remains unchanged during the whole fission
process, i.e., the charge density of the compound nucleus is maintained. By combining Langevincalculations with a statistical model implemented in the CCONE [11], we calculated independent yields and prompt neutron emissions. Excitation energy partitions for two fragments are
determined by the anisothermal model [27].

3Results and Discussion(a) pre-neutron emission
yield of fission products(b) mass-dependent prompt
neutron multiplicity(c) post-neutron emission
yield of fission products

Figure 1: (a) The calculated a pre-neutron emission fission fragment mass yield for 236 U (E∗ =15 MeV) compared with experimental data for the thermal neutron-induced fission on 235 U [28,29, 30, 31, 32, 33]. (b) The calculated mass-dependent prompt neutron multiplicity comparedwith experimental data [34, 35, 36]. (c) The calculated post-neutron emission fission fragment
mass distribution compared with JENDL-FPY/2011 [39].
In this study, we choose the fission of a 236 U compound nucleus (E∗ = 15 MeV), which is easy
to obtain enough statistics due to the properties of Monte Carlo calculations, and compare withexperimental data of thermal neutron-induced fission. Although the compound systems of thecalculation and experimental data are not identical, we think that this comparison is reasonablewith respect to the test of our calculation for the moment. In future work, we try to reducethe compound excitation energy of 236 U. Figure 1(a) shows the calculated fission fragment mass
distribution, compared with experimental data [28, 29, 30, 31, 32, 33]. The calculated resultshows a good agreement with the experimental data. However, the positions of the peaks areslightly different and the mass-symmetric fission component is larger than in the experimental
data. This may be due to the higher excitation energy of the compound nucleus than thermal- 134 134

JAEA-Conf 2023-001

neutron-induced fission in the experimental data. The prompt neutron emission multiplicity wascalculated using the CCONE code with the results of the Langevin calculation as input data. It
is shown in Fig. 1(b). The result reasonably reproduces the sawtooth structure of experiment
data [34, 35, 36]. The calculated average number of the prompt neutron was 1.88, which is lower
than the experimental value of 2.43 [35]. This is thought to be due to discrepancies between thecalculation result and the experiment data of FFMDs or the calculation accuracy of the charge
distribution model (UCD) employed. Figure 1(c) also indicates that the CCONE calculation
for the neutron evaporation process successfully reproduces the post-neutron mass distribution.
The pre-neutron distribution represented by the double-humped shape is symmetric with respect
to mass number, and the symmetry is broken after the prompt neutron emission.

Figure 2: Comparison of the calculated independent yield YI (Z, A) with the experimental data.
We compare our calculated independent yield YI (Z, A) for several fission products with theexperimental data of Rudstam et al. [40] as shown in Fig. 2. This result is extremely importantin r-process calculations. Although it is not able to fit the experimental data precisely, especiallyin the mass region from 115 to 130, the general tendency is well reproduced.

Figure 3: The calculation results of FFMDs for 250 U to 256 U with the excitation energy of E∗= 7 MeV compared with the data from GEF code [38].
We perform a series of fission calculations for uranium (Z = 92) isotopes with 10–20 moreneutron-rich from the β-stability line. The calculated FFMDs for 250 U to 256 U are shown in
Fig. 3. We found that the fission fragment distribution changes from the two-peak feature(mass-asymmetric fission) to the one-peak (mass-symmetric fission) with increasing the neutron
number. A similar trend which is the dramatic change of FFMDs for fermium isotopes [37] wasalso observed in uranium isotopes in this calculation. This trend did not appear in the resultsof the GEF model code [38].

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4Summary

In the presented work, we have performed the fission calculations of 236 U and neutron-rich uranium using the dynamical model aiming at its application to r-process simulations. In thisstudy, we have combined Langevin calculations with the statistical model implemented in the
CCONE code to calculate prompt neutron emissions, and calculated fission fragment mass distributions of neutron-rich nuclei. The calculated prompt neutron emission multiplicity reproduced
the sawtooth structure of experiment data. In the calculated FFMDs in neutron-rich uranium,
the dramatic change of fission mode was observed with increasing mass number. Such a systematic behavior can be significant to shape the final abundances of the r-process calculations.
Our results, including further improvements, are expected to contribute to understanding the
r-process. In future work, the mass number and charge distribution of fission fragments, kinetic
energy, prompt neutron number, lifetime, etc., which are necessary for numerical data available for r-process calculations, will be evaluated for each nuclide simultaneously, and a fission
database will be constructed.

References[1] C. J. Horowitz et al. J. Phys. G: Nucl. Part. Phys. 46, 083001 (2019).
[2] M. Arnould, S. Goriely and K. Takahashi, Phys. Rep. 450, 97 (2007).
[3] John J. Cowan, Christopher Sneden, James E. Lawler, Ani Aprahamian, Michael Wiescher,Karlheinz Langanke, Gabriel Martı́nez-Pinedo, and Friedrich-Karl Thielemann, Rev. Mod.
Phys. 93, 015002 (2021).
[4] S. Goriely, J.-L. Sida, J.-F. Lemaı̂tre, S. Panebianco, N. Dubray, S. Hilaire, A. Bauswein,and H.-T. Janka, Phys. Rev. Lett. 111, 242502 (2013).
[5] M. Eichler et al., Astrophys. J. 808, 30 (2015).
[6] S. Shibagaki et al., Astrophys. J. 816, 79 (2016).
[7] Nicole Vassh et al., Astrophys. J. 896, 28 (2020).
[8] Y. Zhu et al 2018 Astrophys. J. Lett. 863, L23 (2018).
[9] Shinya Wanajo, Astrophys. J. 868, 65 (2018).
[10] S. Tanaka, and Y. Aritomo, Y. Miyamoto, K. Hirose, K. Nishio, Phys. Rev. C 100, 064605(2019).
[11] O. Iwamoto, N. Iwamoto, S. Kunieda, F. Minato, K. Shibata, Nuclear Data Sheets, Volume
131, pp. 159-288 (2016).
[12] Y. Aritomo and M. Ohta, Nucl. Phys. A 744, 3 (2004).
[13] Y. Aritomo, S. Chiba, and F. Ivanyuk, Phys. Rev. C 90, 054609 (2014).
[14] J. Maruhn and W. Greiner, Z. Phys. 251, 431 (1972).
[15] K. Sato, A. Iwamoto, K. Harada, S. Yamaji, and S. Yoshida, Z. Phys. A 288, 383 (1978).
[16] H. J. Krappe, J. R. Nix, and A. J. Sierk, Phys. Rev. C 20, 992 (1979).
[17] V. M. Strutinsky, Nucl. Phys. A 95, 420 (1967).
[18] V. M. Strutinsky, Nucl. Phys. A 122, 1 (1968).
[19] S. G. Nilsson, C. F. Tsang, A. Sobiczewski et al., Nucl. Phys. A 131, 1 (1969).
[20] A. V. Ignatyuk, G. N. Smirenkin, and A. S. Tishin, Sov. J. Nucl. Phys. 21, 255 (1975).
[21] J. Toke and W. J. Swiatecki, Nucl. Phys. A 372, 141 (1981).

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JAEA-Conf 2023-001[22] K. Hirose, K. Nishio, S. Tanaka, R. Léguillon, H. Makii, I. Nishinaka, R. Orlandi, K.
Tsukada, J. Smallcombe, M. J. Vermeulen, S. Chiba, Y. Aritomo, T. Ohtsuki, K. Nakano,
S. Araki, Y. Watanabe, R. Tatsuzawa, N. Takaki, N. Tamura, S. Goto, I. Tsekhanovich,and A. N. Andreyev, Phys. Rev. Lett. 119, 222501 (2017).
[23] Y. Miyamoto, Y. Aritomo, S. Tanaka, K. Hirose, and K. Nishio, Phys. Rev. C 99, 051601(R)(2019).
[24] J. Blocki, Y. Boneh, J. R. Nix, J. Randrup, M. Robel, A. J. Sierk, and W. J. Swiatecki,
Ann. Phys. 113, 330 (1978).
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[26] H. Feldmeier, Rep. Prog. Phys. 50, 915 (1987).
[27] T. Kawano, P. Talou, I. Stetcu, M. B. Chadwick, Nucl. Phys. A 913, 51 (2013).
[28] PP. D ’yachenko, BD. Kuzminov, and MZ. Tarasko, Soviet J. Nucl. Phys. 8, 165 (1969).
[29] S. Zeynalov, W. Furman, and FJ. Hambsch, ISINN-13. (2006).
[30] H. Baba, T. Saito, N. Takahashi, and et al., J. Nucl. Sci. Technol. 34, 871–881 (1997).
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220–229 (1990).
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Walter Loveland, Jan Blomgren, Henri Condé, Marieke Duijvestijn, and Arjan Koning, AIP
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[38] K.-H. Schmidt, B. Jurado, C. Amouroux, and C. Schmitt, Nucl. Data Sheets 131, 107(2016).
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Katakura, and N. Otuka, Journal of Korean Physical Society 59, 1046 (2011).
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Acknowledgments
This study is financially supported by JSPS KAKENHI (19H00693, 20K04003, 20H05648,
21H01087, 22K20373). Parts of computations are performed on computer facilities at CfCA
in NAOJ and at YITP in Kyoto University.

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22. Extension of R-matrix code AMUR toward
analysis on actinide nuclei-A feasibility study on 233USatoshi KUNIEDA†1
1

Nuclear Data Center, Japan Atomic Energy Agency (JAEA)†
Email: kunieda.satoshi@jaea.go.jp

Abstract
The extension of an R-matrix code AMUR is now under progress for analysis of neutron
cross-section on heavier nuclei. This paper shortly summarizes recent updates in the code for thetheoretical calculation of the resonant cross-sections. In this work, with the preliminary versionof AMUR, let me also demonstrate a feasibility analysis to experimental neutron crosssections on 233U which are stored in the EXFOR database. It was confirmed that the values of
the resonance parameters were successfully obtained through the fitting procedure, together with
their covariance data. It was also found that some characteristics of nuclear reactions could beseen in correlation matrices of the cross-sections.

1

Introduction

The AMUR code [1, 2] is under development in JAEA for the cross-section evaluation in the
resolved resonance energy region. The code is based on the R-matrix theory [3] for calculation ofcross-sections and the Kalman filtering method [4] for the data-assimilation, which enables us toobtain resonance parameter set from the measured cross-sections with its covariance matrix. The
code was initially designed for the analysis of the light-nuclei to narrow large differences ofcross-sections among evaluations in the world (e.g., on n+16O [1]). Indeed, it was applied to thedevelopment of JENDL-5 [5] for a number of light-mass isotopes. It may be a positive idea toextend applicability of the code toward the analysis of heavier nuclei including structural materials,
major and minor actinide nuclei.
The cross-sections of the radiative neutron capture reaction are very important for medium-and
heavy-mass nuclei in a number of practical applications. Those of the fission reaction are also
highly important for actinide isotopes in design of the reactors. However, it is unrealistic to fully
apply the R-matrix theory to calculation of those cross-sections due to lack of fundamental
information and huge number of the explicit channels. Therefore, we need to use an approximated theories/formulae of R-matrix (such as of the Breit-Wigner or Reich-Moore types) to
calculate those cross-sections. The AMUR code is now being in progress to have a flexibility
which allows those approximated calculations for the resonance analysis. In this work, a test
analysis is performed for neutron cross-sections on 233U to see feasibilities of the updated version of
AMUR. The scope of this study includes estimation of covariance data both for the resonanceparameters and the cross-sections.

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2Updates toward analysis of heavier nuclei

AMUR was initially developed for the analysis of the light-nuclei to narrow large differencesamong the evaluated cross-sections, by making use of the theoretical constraints [1] from the Rmatrix theory. The code was also designed to analyze covariance data of the resonanceparameters and cross-sections, where both the experimental and theoretical knowledge werereflected to the nuclear data evaluation [2]. We thought such an idea/approach could also be applied toanalysis of the heavier nuclei with AMUR, learning a number of experiences on the other codessuch as SAMMY [6] and REFIT [7].
Recently, the authors extended capabilities of the code toward the analysis of medium- andheavy-mass nuclei to fully cover range of isotopes required for nuclear science and engineering. In
the theoretical part, AMUR is able to read a resonance parameter set stored in the ENDF-6 format(MF=2, LRU=1) files, then it performs reconstruction of cross-sections with the Breit-Wigner(LRF=1,2) or the Reich-Moore type formulae (LRF=3,7). That means the code is able to calculate theradiative neutron capture and fission cross-sections with approximated/reduced R-matrix formulae.
The code is also able to perform the Doppler broadening with the free-gas approximation.
Therefore, AMUR is getting equivalent to the other resonance analysis and the processing codes interms of basic capabilities for calculating/reconstructing the cross-sections.

3

Test analysis on 233U and preliminary results

3.1

Resonance analysis

The 233U isotope was selected in this study because,• Experimental data of the resonant neutron cross-sections compiled in the EXFOR database arevery limited for a number of the medium- and heavy-mass nuclei. Fortunately, a few of data-sets
were available for 233U in which the transmission, (n,γ) and (n,f) cross-sections were given in thesame energy range, which allowed us to perform a consistent resonance analysis in terms of thereaction channels.
• Until now, AMUR had not been applied to analysis on the actinide isotope. Thus it was agood practice for AMUR to analyze fission cross-sections for the first time, as the 233U
isotope is one of the well-known fissioning nuclei.
• It is physically interesting to see correlation matrices of cross-sections amongst all thereactions involved, including the fission channel.
The experimental data analyzed in this work were those by Guber et al. [8] for transmission and by
Berthoumieux et al. [9] for the (n,γ) and (n,f) cross-sections. According to literatures of those data, allthey were the time-of-flight measurements with very high energy-resolutions. Furthermore, corrections
for the multiple-scattering and self-shielding effects had also been made at least for the (n,γ) and (n,f)
cross-sections. Therefore, in this test/preliminary analysis, only the temperature effect was considered
for the experimental correction in AMUR, viz., the experimental corrections are to be performed inforthcoming in-depth studies.
The initial values of resonance parameters were taken from ENDF/B-VIII.0 [10] where all theparameters were defined in the Reich-Moore formula (MF=2/LRF=3) for this isotope. The parametersearch was performed simultaneously for all the reactions up to En = 20 eV. Figure 1 illustrates fitting
results for the transmission, (n,γ) and (n,f) cross-sections. We have not yet made thorough comparisonswith other codes, however, this figure visually suggests AMUR is getting equivalent with the otherresonance analysis codes in terms of basic capabilities for the reconstructing cross-sections and thefitting to those experimental data.

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Transmission (-)

JAEA-Conf 2023-001

233

U(n,tot), Guber+ (2001)

1

0.5

σ (barn)

0

5

10

15

20

Neutron Energy (eV)

233

400

U(n,γ ), Berthoumieux+ (2007)

200

0

σ (barn)

0

5

10

233

U(n,f),

800

15

20

Neutron Energy (eV)Berthoumieux+ (2007)

600
400
200
0

5

10

15

20

Neutron Energy (eV)Figure 1: Fitting results of AMUR to experimental data of the neutron transmission [8], (n,γ) and (n,f)
cross-sections [9].

3.2Resulting correlation matrices and uncertainty of cross-sections

The covariance matrix of all the resonance parameters was obtained during the fitting procedure
with the Kalman filtering method. Once we calculate sensitivity matrices of the parameter to crosssections, covariance/correlation matrices of cross-sections are deduced by the propagation law. Figure 2
illustrates correlation matrices obtained in this analysis for the total, elastic scattering, (n,γ) and (n,f)
cross-sections. We see overall features of those plots are complicated because of the interference effects
on the resonant nuclear reaction. A very strong long-range correlation is seen in the elastic scatteringcross-sections. It is because that the shape elastic scattering process, which is calculated by the hardsphere model in R-matrix, always occurs over the energy range. More in-depth discussion may bepossible if we perform experimental corrections in the fitting procedure.
Figure 3 illustrates preliminary results on uncertainty of cross-sections which were propa-gatedfrom those of the resonance parameters. The values are around 1% on average, but they are
fluctuated due to constraints from the resonance t heory. Because there were no data points below 1
eV in the measurements I analyzed, uncertainties resulted in very large values for all the reactions.

4

Summary

The extension of an R-matrix code AMUR is now under progress for analysis of neutron
cross-section on heavier nuclei, in which approximated R-matrix theories are incorporated to- 140 140

JAEA-Conf 2023-001

Figure 2: Correlation matrices obtained in this analysis for the total, elastic scattering, (n,γ) and (n,f)
cross-sections.
the code. Such an update enables us to perform resonance analysis of the neutron capture andfission cross-sections, as a test analysis was demonstrated for the 233U isotope in this work.
Development of the code will be continued to have enough options for experimental corrections,which may allows us in-depth studies not only for the evaluation of cross-sections but also for
estimation of their covariance data.

References[1] Kunieda S, Kawano T, Paris M, et al. R-matrix analysis for n +16O cross-sections up to
En=6.0 mev with covariances. Nucl Data Sheets. 2014;118:250.
[2] Kunieda S, Kawano T, Paris M, et al. Covariance of neutron cross sections for 16O throughmatrix analysis. Nucl Data Sheets. 2015;123:159.
[3] Lane AM, Thomas RG. R-matrix theory of nuclear reactions. Rev Mod Phys. 1958;30:257–353.
[4] Kawano T, Matsunobu H, Murata T, et al. Simultaneous evaluation of fission cross sections ofuranium and plutonium isotopes for JENDL-3.3. J Nucl Sci Technol. 2000; 37:327.
[5] Iwamoto O, Iwamoto N, Kunieda S, et al. Japanese Evaluated Nuclear Data Library version 5:
JENDL-5. J Nucl Sci Technol. 2023; 60:1-60.

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Figure 3: Uncertainty of cross-sections obtained in this analysis for the total, elastic scattering,(n,γ) and(n,f) cross-sections.
[6] Larson MN. Updated user’s guide for SAMMY: Multi-level R-matrix fits to neutron datausing Bayes’ equations ; 1998. ORNL/TM-9179/R4. Oak Ridge National Laboratory; 1998.
[7] Moxon MC, Ware TC, Dean CJ. Users’ guide for REFIT-2009-10 ; 2010. UKNSF; 2010
April. pp. 243. UK Nuclear Science Forum.
[8] Guber KH, Spencer RR, Leal LC, et al. High-resolution transmission measurements of 233U
using a cooled sample at the temperature T= 11 K. Nuclear Science and Engineering. 2001;
139(2):111–117.
[9] Berthoumieux E, Abbondanno U, Aerts G, et al. Simultaneous measurement of the neutron
capture and fission yields of 233U. In: International Conference on Nuclear Data for Science andTechnology; 2007. pp. 571–574.
[10] Brown DA, Chadwick MB, Capote R, et al. ENDF/B-VIII.0: The 8th major release of thenuclear reaction data library with CIELO-project cross sections, new standards and thermal
scattering data. Nuclear Data Sheets. 2018;148:1–142. Special Issue on Nuclear ReactionData.

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23.

Processing of JENDL-5 Photonuclear Sublibrary

Chikara KONNO*Japan Atomic Energy Agency
2-4 Shirakata, Tokai-mura, Naka-gun, Ibaraki-ken 319-1195, Japan*

Email: konno.chikara@jaea.go.jp

I modified NJOY2016.67 to produce photonuclear ACE files which can be used in MCNP6.2 andPHITS3.27 and produced the ACE file of the JENDL-5 photonuclear sub-library. Simple test
calculations with the produced ACE file revealed that the produced ACE file had no serious problems.

1. Introduction
In order to use JENDL-5 [1], which was released in 2021, in MCNP [2] and PHITS [3], its ACE fileshould be produced. The ACE file of the JENDL-5 neutron sublibrary was produced based on FRENDY[4] and those of the JENDL-5 charged particle and photoatomic sublibraries were generated based on amodified version of NJOY2016.65 [5], which is described elsewhere [6]. The remaining issue is to
produce an ACE file of the JENDL-5 photonuclear sublibrary. The current FRENDY cannot process the
JENDL-5 photonuclear sublibrary. The latest NJOY, NJOY2016.67, can produce the ACE file of the
JENDL-5 photonuclear sublibrary, but MCNP6.2 and PHITS3.27 cannot use the produced ACE filebecause of an unsupported format. I have produced the ACE file of the JENDL-5 photonuclear sublibrarywhich can be used in MCNP6.2 and PHITS3.27 by modifying NJOY2016.67.

2. Problems of NJOY2016
NJOY2016.67 converts the energy-angle distribution data of LAW=1 (continuum energy-angle
distribution) and LANG=1 (Legendre coefficients are used) in ENDF-6 files [7], which are adopted inmost of the nuclei in the JENDL-5 photonuclear sublibrary, to the energy-angle distribution data of
LAW=61 (tabular energy distribution) in ACE files. However MCNP6.2 and PHITS3.27 do not support
the LAW=61 format in photonuclear ACE files and cannot use it (The next version of MCNP, MCNP6.3,
will be able to use it but has not been released yet.). The conversion of the energy-angle distribution dataof LAW=1 and LANG=1 in ENDF-6 files to the energy-angle distribution data of LAW=61 in ACE files
was introduced in NJOY2016.66, which also includes other important revisions for photonuclear data
(Example : Some photonuclear libraries have MF6/MT18 with a neutron multiplicity equal to 1 insteadof nubar. In this case the neutron multiplicity is replaced with the nubar data.). NJOY2016.65 converts
the energy-angle distribution data of LAW=1 and LANG=1 in ENDF-6 files to the energy distribution
data of LAW=4 (angular distribution should be defined separately) with an isotropic angular distribution
in ACE files, which MCNP6.2 and PHITS3.27 can use, but it cannot produce complete ACE files of the
JENDL-5 photonuclear sublibrary because of any bugs.

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3. Modification of NJOY2016
I modified NJOY2016.67 only in the conversion of the energy-angle distribution data of LAW=1and LANG=1 in ENDF-6 files on the basis of NJOY2016.65 to produce the ACE file with LAW=4 of the
JENDL-5 photonuclear sublibrary, which can be used in MCNP6.2 and PHITS3.27. I also modified
NJOY2016.67 to fix the following problems. The details of the modification are described elsewhere [6].
The problem that NJOY2016.65 cannot produce the complete ACE file with LAW=4 of the
JENDL-5 photonuclear sublibrary still remained in NJOY2016.67. This problem occurred in theconversion of the energy-angle distribution data of LAW=1 and LANG=1 in ENDF-6 files to theenergy distribution data of LAW=4 in ACE files.



Zero division in normalization of the probability density distribution in 245Bk, 244Cf, 253Cf, and
251Fm.

No support of the multiple interpolation in MF6/MT5 data in 3He, 6Li, 7Li, 9Be, 10B, and 11B.
Negative heating numbers in a lot of nuclei were set to 0.0 as shown in Figs. 1 and 2. This
modification was based on IAEA photonuclear processing [8].

Double counting problem of heating number for LAW=2 data of MF6/MT5 in 3He.

Fig. 1 Heating number of 49S (whole).

Fig. 2 Heating number of 49S (expanded).

The following NJOY2016 processing problems pointed out by IAEA [8] remain in the present
processing. Note that IAEA used the ACEMAKER code [9], which solves the problems but produces
ACE files with LAW=61 data, for processing IAEA photonuclear data library (IAEA/PD-2019) [10].


The photofission delayed fission neutron data were neglected.

Relativistic conversion between the center of mass system and the laboratory reference framework
was not applied.
Inadequate treatment of LAW=4 data for MF6/MT5 in 2H.



Inadequate treatment of LAW=2 data for MF6/MT5 in 3He.

The first issue is not responsible to NJOY2016 because the ENDF-6 format does not support photofission
delayed fission neutron data. The other issues affect the heating number. While the effect of the second
issue is only less than 5% [8], those of the third and fourth issues are very large as shown in Figs. 3 and 4,

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JAEA-Conf 2023-001

Fig. 3 Heating number of 2H.

Fig. 4 Heating number of 3He.

where IAEA calculates the heating numbers correctly with ACEMAKER. Note that the 2H and 3He
ENDF-6 files in the JENDL-5 photonuclear sublibrary are almost the same as those in IAEA/PD-2019.
Thus I manually replaced the heating numbers in the 2H and 3He ACE files of the JENDL-5 photonuclear
sublibrary with those of IAEA/PD-2019.

4. Test Calculations
I produced the ACE file of the JENDL-5 photonuclear sublibrary with the modified version of
NJOY2016.67. As a test I calculated angular neutron spectra produced from gold (1 cm φ, 1 cm thick)bombarded with 25 MeV photons by using MCNP6.2 and the following ACE files.


JENDL-5 (Present production)

IAEA/PD-2019 (197Au:JENDL/PD-2016.1 [11], old official ACE file with LAW=4)

TENDL-2019 (official ACE file) [12](a) 0 degree(b) 90 degree
Fig. 5 Calculated angular neutron spectra produced from gold bombarded with 25 MeV photons.

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JAEA-Conf 2023-001

The calculated neutron spectra at 0 and 90 degrees are shown in Fig. 5. The spectra with JENDL-5
are almost the same as those with IAEA/PD-2019, where the 197Au file is that of JENDL/PD-2016.1
which is almost the same as that of JENDL-5. Thus the processing of the JENDL-5 photonuclear
sublibrary is considered to have no serious problems.

5. Conclusion
I produced the ACE file of the JENDL-5 photonuclear sublibrary with a modified version of
NJOY2016.67. The produced photonuclear ACE files can be used in MCNP6.2 and PHITS3.27. Note thatthe heating numbers of 2H and 3He were manually replaced with those of IAEA/PD-2019 because they
were too large. Test calculations indicated that the ACE file had no serious problems. The ACE file of
the JENDL-5 photonuclear sublibrary was released with other JENDL-5 ACE files from JAEA web site
[6] as an open source. Users can freely download and use it.

References
1)

Iwamoto, O., Iwamoto, N., Kunieda, S., et al., Japanese Evaluated Nuclear Data Libraryversion 5 : JENDL-5, to be published in J. Nucl. Sci. Technol.

2)Werner, C.J. (Ed.), MCNP® USER’S MANUAL Code Version 6.2, LA-UR-17-29981, 2017,
746p.

3)
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