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rays in the 
La(
)
La reactionOkuizumi, Mao*; Auton, C. J.*; Endo, Shunsuke; Fujioka, Hiroyuki*; Hirota, Katsuya*; Ino, Takashi*; Ishizaki, Kohei*; Kimura, Atsushi; Kitaguchi, Masaaki*; Koga, Jun*; et al.
Physical Review C, 111(3), p.034611_1 - 034611_6, 2025/03
Times Cited Count：1 Percentile：59.26(Physics, Nuclear) rays from a neutron-induced 
-wave resonance of 
XeOkudaira, Takuya*; Tani, Yuika*; Endo, Shunsuke; Doskow, J.*; Fujioka, Hiroyuki*; Hirota, Katsuya*; Kameda, Kento*; Kimura, Atsushi; Kitaguchi, Masaaki*; Luxnat, M.*; et al.
Physical Review C, 107(5), p.054602_1 - 054602_7, 2023/05
Times Cited Count：6 Percentile：67.70(Physics, Nuclear)no abstracts in English
rays in the 
Sn(
)
Sn reactionEndo, Shunsuke; Okudaira, Takuya*; Abe, Ryota*; Fujioka, Hiroyuki*; Hirota, Katsuya*; Kimura, Atsushi; Kitaguchi, Masaaki*; Oku, Takayuki; Sakai, Kenji; Shima, Tatsushi*; et al.
Physical Review C, 106(6), p.064601_1 - 064601_7, 2022/12
Times Cited Count：9 Percentile：70.62(Physics, Nuclear)no abstracts in English
rays from the -wave resonance of SnKoga, Jun*; Takada, Shusuke*; Endo, Shunsuke; Fujioka, Hiroyuki*; Hirota, Katsuya*; Ishizaki, Kohei*; Kimura, Atsushi; Kitaguchi, Masaaki*; Niinomi, Yudai*; Okudaira, Takuya*; et al.
Physical Review C, 105(5), p.054615_1 - 054615_5, 2022/05
Times Cited Count：8 Percentile：66.85(Physics, Nuclear)no abstracts in English
rays in the La(
)La
reactionOkudaira, Takuya*; Endo, Shunsuke; Fujioka, Hiroyuki*; Hirota, Katsuya*; Ishizaki, Kohei*; Kimura, Atsushi; Kitaguchi, Masaaki*; Koga, Jun*; Niinomi, Yudai*; Sakai, Kenji; et al.
Physical Review C, 104(1), p.014601_1 - 014601_6, 2021/07
Times Cited Count：8 Percentile：61.08(Physics, Nuclear)-rays from La+n to excited states of LaOkudaira, Takuya; Endo, Shunsuke; Hirota, Katsuya*; Ishizaki, Kohei*; Kimura, Atsushi; Kitaguchi, Masaaki*; Koga, Jun*; Sakai, Kenji; Shimizu, Hirohiko*; Takada, Shusuke*; et al.
JPS Conference Proceedings (Internet), 33, p.011121_1 - 011121_3, 2021/03
The technology development section develops the neutron polarization device: 
He Spin Filter, which can polarize neutrons in wide energy range. Polarized epi-thermal neutrons, which can be produced using He spin filter, can be useful for fundamental physics. Time-reversal violation beyond the Standard Model of elementary particles is one of the biggest problems to solve the mystery of the origin of the universe. An experiment with polarized epi-thermal neutrons and a polarized target to search for the T-violation using compound nuclei is planned at J-PARC. The measurement result of the angular distributions of -rays from La+n to excited states of La is presented.
Sakai, Kenji; Oku, Takayuki; Okudaira, Takuya; Kai, Tetsuya; Harada, Masahide; Hiroi, Kosuke; Hayashida, Hirotoshi*; Kakurai, Kazuhisa*; Shimizu, Hirohiko*; Hirota, Katsuya*; et al.
JPS Conference Proceedings (Internet), 33, p.011116_1 - 011116_6, 2021/03
In neutron fundamental physics, study of correlation term 
of a neutron spin 
and a target nuclear spin 
is important because term interferes to parity non-conserving (PNC) and time reversal non-conserving terms. For this study, a xenon (Xe) is an interesting nucleus because it has been observed an enhancement of PNC effect around neutron resonance peaks, and polarizes up to 
by using a spin exchange optical pumping (SEOP) method. We would plan to develop a polarized Xe gas target with a compact in-situ SEOP system, and to study term by utilizing epithermal neutron beams supplied from a high intense pulsed spallation neutron source. As the first step, we attempted to measure neutron polarizing ability caused by term at a 9.6 eV s-wave resonance peak of 
Xe at BL10 in MLF, by detecting change 
of ratio between neutron transmissions with the polarized and unpolarized Xe target. After demonstrating that our apparatus could detect small change (
) of neutron transmissions caused by Doppler broadening effect, a signified value of has been obtained as preliminary results. For analyzing the obtained in detail, we are improving our nuclear magnetic resonance and electron paramagnetic resonance systems for evaluating Xe polarization independently of neutron beams.
He neutron spin filter at J-PARCOkudaira, Takuya; Oku, Takayuki; Ino, Takashi*; Hayashida, Hirotoshi*; Kira, Hiroshi*; Sakai, Kenji; Hiroi, Kosuke; Takahashi, Shingo*; Aizawa, Kazuya; Endo, Hitoshi*; et al.
Nuclear Instruments and Methods in Physics Research A, 977, p.164301_1 - 164301_8, 2020/10
Times Cited Count：25 Percentile：90.03(Instruments & Instrumentation) rays from neutron-induced compound states of LaYamamoto, Tomoki*; Okudaira, Takuya; Endo, Shunsuke; Fujioka, Hiroyuki*; Hirota, Katsuya*; Ino, Takashi*; Ishizaki, Kohei*; Kimura, Atsushi; Kitaguchi, Masaaki*; Koga, Jun*; et al.
Physical Review C, 101(6), p.064624_1 - 064624_8, 2020/06
Times Cited Count：19 Percentile：82.45(Physics, Nuclear)-rays after neutron capture by La for a T-violation searchOkudaira, Takuya; Shimizu, Hirohiko*; Kitaguchi, Masaaki*; Hirota, Katsuya*; Haddock, C. C.*; Ito, Ikuya*; Yamamoto, Tomoki*; Endo, Shunsuke*; Ishizaki, Kohei*; Sato, Takumi*; et al.
EPJ Web of Conferences, 219, p.09001_1 - 09001_6, 2019/12
Parity violating effects enhanced by up to 10
times have been observed in several neutron induced compound nuclei. There is a theoretical prediction that time reversal (T) violating effects can also be enhanced in these nuclei implying that T-violation can be searched for by making very sensitive measurements. However, the enhancement factor has not yet been measured in all nuclei. The angular distribution of the (n,) reaction was measured with La by using a germanium detector assembly at J-PARC, and the enhancement factor was obtained. From the result, the measurement time to achieve the most sensitive T-violation search was estimated as 1.4 days, and a 40% polarized La target and a 70% polarized He spin filter whose thickness is 70 atm
cm are needed. Therefore high quality He spin filter is developed in JAEA. The measurement result of the (n,) reaction at J-PARC and the development status of the He spin filter will be presented.
Okudaira, Takuya; Oku, Takayuki; Sakai, Kenji; Ino, Takashi*; Hayashida, Hirotoshi*; Hiroi, Kosuke; Shinohara, Takenao; Kakurai, Kazuhisa*; Aizawa, Kazuya; Shimizu, Hirohiko*; et al.
Proceedings of Science (Internet), 356, p.029_1 - 029_5, 2019/12
The technology development section carries out the development of the neutron polarization device: He Spin Filter. It is often used for the fundamental physics region. In order to explain the matter-dominated universe, a time reversal violation is necessary and searches for new physics are conducted in the world. The T-violation search using a polarized neutron beam is planned at J-PARC. A large He spin filter is needed to polarize high energy neutrons for the experiment and is developed in JAEA. Recently, we developed the accurate measurement system to evaluate the polarization of He and a vacuum system to make the He spin filter, and large He spin filters for epi-thermal neutron was made using the system. The current status of the development of the He spin filter will be talked.
rays from neutron-induced compound states of LaOkudaira, Takuya*; Takada, Shusuke*; Hirota, Katsuya*; Kimura, Atsushi; Kitaguchi, Masaaki*; Koga, Jun*; Nagamoto, Kosuke*; Nakao, Taro*; Okada, Anju*; Sakai, Kenji; et al.
Physical Review C, 97(3), p.034622_1 - 034622_15, 2018/03
Times Cited Count：20 Percentile：78.13(Physics, Nuclear)-rays at the ANNRI in the MLF of the J-PARCTakada, Shusuke*; Okudaira, Takuya*; Goto, Fumiya*; Hirota, Katsuya*; Kimura, Atsushi; Kitaguchi, Masaaki*; Koga, Jun*; Nakao, Taro*; Sakai, Kenji; Shimizu, Hirohiko*; et al.
Journal of Instrumentation (Internet), 13(2), p.P02018_1 - P02018_21, 2018/02
Times Cited Count：8 Percentile：31.78(Instruments & Instrumentation)Wakui, Takashi; Saito, Shigeru; Yamasaki, Kazuhiko*; Sakai, Tomoki*; Mori, Kotaro*; Futakawa, Masatoshi
no journal, ,
Irradiation damage due to protons and neutrons reduces ductility in the mercury target vessel of J-PARC. The radiation damage is one of the factors that determine the lifetime. The evaluation of the irradiation damage is extremely important for long-term operation at high beam power. A simple and rapid indentation technique is investigated in order to evaluate mechanical properties. Ion irradiation is a technique for simulating radiation damage, but the damage area is limited to the very surface layer. Therefore, we propose a mechanical property evaluation technique using an inverse analysis combining a Kalman filter and numerical experiments to the load-depth curve. As a result, changes in the mechanical properties due to ion irradiation were detected and it was confirmed that this evaluation technique was very effectiveness. In addition, the technique was applied to lead glass, and it was clarified that the microplastic behavior of glasses can be evaluated quantitatively.
Sakai, Tomoki*; Wakui, Takashi; Saito, Shigeru; Futakawa, Masatoshi; Mori, Kotaro*
no journal, ,
Radiation damage to materials is a factor that determines the lifetime of equipment used in high-radiation environments, and it is essential to understand the radiation damage. Ion irradiation has been used as a method of simulating irradiation damage, but the damage area is limited to the thin surface layer and has a gradient damage distribution. Therefore, micro-indentation test was applied as the method to investigating the mechanical properties and then the hardness in irradiated and unirradiated area. Increase of hardness due to irradiation was confirmed and the hardness increased by adding light ion. On the other hand, amount of increase in hardness decreased with increasing the irradiation temperature.
He spin filter for the time reversal violation search using compound nuclei at JAEAOkudaira, Takuya; Oku, Takayuki; Sakai, Kenji; Ino, Takashi*; Hayashida, Hirotoshi*; Hiroi, Kosuke; Shinohara, Takenao; Kakurai, Kazuhisa*; Aizawa, Kazuya; Shimizu, Hirohiko*; et al.
no journal, ,
The technology development section carries out the development of the neutron polarization device: He Spin Filter. Since this device is often used for the fundamental physics region, it is important to cooperate with scientists in this region for further development. In order to explain the matter-dominated universe, a time reversal violation is necessary and searches for new physics are conducted in the world. The T-violation search experiment using a polarized neutron beam is planned at J-PARC. A large He spin filter is needed to polarize epi-thermal neutron for the experiment and is developed in JAEA. Recently, user's experiments for the T-violation search using He spin filter were conducted. The current status of the development of the He spin filter and feature plan will be presented.
Wakui, Takashi; Saito, Shigeru; Wakai, Eiichi; Sakai, Tomoki*; Mori, Kotaro*; Futakawa, Masatoshi
no journal, ,
One of dominant factors to determine the lifetime of the mercury target in J-PARC is the radiation damage. Authors suggested the tensile properties evaluation technique from numerical tensile tests using material properties estimated from inverse analyses on indentation tests. The technique was applied to ion-irradiated materials, and the validity of the technique was investigated by comparing the result with results of the PIE on the targets of SNS. By conducting indentation tests on samples cut out from used targets, it is expected that the residual lifetime estimation can be conducted considering various effects; fatigue, temperature, LME, etc. superimposed on the radiation damage from evaluating hardness and tensile properties obtained by the technique. The technique and comparison results will be discussed.
Sakai, Tomoki*; Wakui, Takashi; Saito, Shigeru; Futakawa, Masatoshi; Mori, Kotaro*
no journal, ,
One of dominant factors to determine the lifetime of components used under the high-radiation environment is the radiation damage of materials and then understanding of the radiation damage is very important. Although ion irradiation has been conducted as the method simulating the radiation damage, the damaged area is limited to the surface layer of the specimen and has the gradient damage distribution. Micro-indentation tests with a Berkovich indenter were conducted in irradiated and unirradiated area on ion irradiated specimens and the micro-hardness was estimated from load and depth curve. The micro-hardness increased by the irradiation. The micro-hardness increased further under the irradiation condition that hydrogen ion and helium ion were added. On the other hand, the micro-hardness decreased with increasing irradiated temperature.
Sakai, Kenji; Oku, Takayuki; Okudaira, Takuya; Kai, Tetsuya; Harada, Masahide; Hiroi, Kosuke; Hayashida, Hirotoshi*; Shimizu, Hirohiko*; Yamamoto, Tomoki*; Ino, Takashi*; et al.
no journal, ,
In neutron fundamental physics, a study of correlation term of a neutron spin s and a target nuclear spin is important because the term interferes to parity non-conserving (PNC) and time reversal non-conserving (TRNC) terms. For this study, a xenon (Xe) is an interesting nucleus because it has been observed an enhancement of PNC effect around neutron resonance peaks, and polarizes up to 
by using a spin exchange optical pumping (SEOP) method. We attempted to develop a polarized Xe target in a compact 
SEOP system and measure neutron polarizing ability caused by the term at a 9.6 eV 
-wave resonance peak of Xe, by detecting change 
of a ratio between neutron transmissions with the polarized and unpolarized Xe target. As preliminary results, we observed a signified value of 
after demonstrating that our apparatus could distinguish Doppler broadening effect as systematic error.
Wakui, Takashi; Saito, Shigeru; Futakawa, Masatoshi; Sakai, Tomoki*; Mori, Kotaro*
no journal, ,
One of dominant factors to determine the lifetime of the structural components used under high irradiation environment is radiation damage. The indentation test will be applied to understand the degradation in mechanical properties. In this study, the technique evaluating mechanical properties from the combination of the indentation test with inverse analysis and the numerical tensile experiment is proposed. In order to confirm that this technique can evaluate changes in mechanical properties, it was applied to ion irradiated 316L stainless steels. The numerical model consists of multi layers whose mechanical properties are dependent on the DPA distribution. The material constants of each layer were identified. The numerical tensile experiments were conducted by using identified material constants. These results are compared with the PIE results of SNS. As the results, it was confirmed that this technique is effective to evaluate the mechanical property degradation due to irradiation.
Sakai, Kenji; Oku, Takayuki; Harada, Masahide; Kai, Tetsuya; Hiroi, Kosuke; Hayashida, Hirotoshi*; Kira, Hiroshi*; Shimizu, Hirohiko*; Hirota, Katsuya*; Okudaira, Takuya*; et al.
no journal, ,
no abstracts in English
