Kogawa, Hiroyuki; Futakawa, Masatoshi; Haga, Katsuhiro; Tsuzuki, Takayuki*; Murai, Tetsuro*
JAEA-Technology 2022-023, 128 Pages, 2022/11
In a mercury target of the J-PARC (Japan Proton Accelerator Research Complex), pulsed proton beams repeatedly bombard the flowing mercury which is confined in a stainless-steel vessel (target vessel). Cavitation damage caused by the propagation of the pressure waves is a factor of the life of the target vessel. As a measure to reduce damages, we developed a bubbler to inject the gas microbubbles into the flowing mercury, which can reduce the pressure waves. To operate the mercury target vessel stably with the 1 MW high-intensity proton beams, further reduction of the damage is required. The bubbler setting position should be closer to the beam window to increase the bubble population, which could enhance the reduction effect on the pressure waves and damage. However, the space at the beam window of the target vessel is restricted. The bubbler design and setting position as well as the vane design for the mercury flowing pattern are optimized by means of a machine learning technique to get more suitable bubble distribution, increasing in bubble population and optimizing bubble size nearby the beam window of the target vessel. The results of CFD analyses performed with 1000 cases were used for machine learning. Since the flow rate of mercury affects the temperature of the target vessel, this was used for the constraint condition. As a result, we found a design of mercury target vessel that can increase the bubble population by ca. 20% higher than the current design.
Mitsuyasu, Yusuke*; Oka, Toshitaka; Takahashi, Atsushi*; Kino, Yasushi*; Okutsu, Kenichi*; Sekine, Tsutomu*; Yamashita, Takuma*; Shimizu, Yoshinaka*; Chiba, Mirei*; Suzuki, Toshihiko*; et al.
KEK Proceedings 2022-2, p.120 - 125, 2022/11
We investigate the effect of sample's anisotropy and measurement condition to obtain the higher reproducibility for the shape of the ESR spectrum and the intensity of CO radical.
Ishikawa, Ryoya*; Suzuki, Masatoshi*; Kino, Yasushi*; Endo, Satoru*; Nakajima, Hiroo*; Oka, Toshitaka; Takahashi, Atsushi*; Shimizu, Yoshinaka*; Suzuki, Toshihiko*; Shinoda, Hisashi*; et al.
KEK Proceedings 2022-2, p.61 - 66, 2022/11
The balance between oxidative stress and antioxidant activity, which is a defense mechanism against oxidative stress, was investigated in the liver and bladder of wild Japanese macaques captured in Fukushima Prefecture. No significant induction of oxidative stress by exposure to environmental radionuclides after the Fukushima nuclear accident was observed, suggesting that the stress defense mechanism of the organism is activated in some organs.
Mitsuyasu, Yusuke*; Oka, Toshitaka; Takahashi, Atsushi*; Koarai, Kazuma; Kino, Yasushi*; Okutsu, Kenichi*; Sekine, Tsutomu*; Yamashita, Takuma*; Shimizu, Yoshinaka*; Chiba, Mirei*; et al.
KEK Proceedings 2021-2, p.91 - 96, 2021/12
We examined whether the ESR dose estimation method could be applied to wild Japanese macaque. In this work, we investigated the enamel preparation protocol and the analytical method of the ESR spectra.
Komatsu, Kazuki*; Iwasaki, Tsugumi*; Murata, Kosuke*; Yamashiro, Hideaki*; Goh, V. S. T.*; Nakayama, Ryo*; Fujishima, Yohei*; Ono, Takumi*; Kino, Yasushi*; Shimizu, Yoshinaka*; et al.
Reproduction in Domestic Animals, 56(3), p.484 - 497, 2021/03
We have established an archive system of livestock and wild animals from the surrounding ex-evacuation zone. Wildlife within the alert zone have been exposed to low-dose-rate (LDR) radiation for a long and continuous time. In this study, we analysed the morphological characteristics of the testes and in vitro fertilization (IVF) capacity of cryopreserved sperm of raccoons from the ex-evacuation zone of the FDNPP accident. This study revealed that the chronic and LDR radiation exposure associated with the FDNPP accident had no adverse effect on the reproductive characteristics and functions of male raccoons.
Oka, Toshitaka; Takahashi, Atsushi*; Koarai, Kazuma; Mitsuyasu, Yusuke*; Kino, Yasushi*; Sekine, Tsutomu*; Shimizu, Yoshinaka*; Chiba, Mirei*; Suzuki, Toshihiko*; Osaka, Ken*; et al.
Radiation Measurements, 134, p.106315_1 - 106315_4, 2020/06
The relationship between the CO radical intensity and the absorbed dose (dose response curve) of tooth enamel of Japanese macaque was observed by electron spin resonance and the detection limit of our system was estimated to be 33.5 mGy, which is comparable to the detection limit for human molar teeth. Using the dose response curve, external exposure dose for seven wild Japanese macaques captured in Fukushima prefecture were examined. The results suggest that the external exposure dose for the wild Japanese macaques were ranged between 45 mGy to 300 mGy.
Oku, Takayuki; Nakamura, Mitsutaka; Sakai, Kenji; Teshigawara, Makoto; Hideki, Tatsumoto*; Yonemura, Masao*; Suzuki, Junichi*; Arai, Masatoshi*
JAEA-Conf 2015-002, 660 Pages, 2016/02
The twenty first meeting of the International Collaboration on Advanced Neutron Source (ICANS-XXI) was held at Ibaraki Prefectural Culture Center in Mito from 29 September to 3 October 2014. It was hosted by Japan Atomic Energy Agency (JAEA), High Energy Accelerator Research Organization (KEK) and Comprehensive Research Organization for Science and Society (CROSS). In the meeting, new science and technology in the new era with the high power neuron sources were discussed in mostly "workshop style" sessions. In each session, various kinds of issues related to not only the hardware, but also the software and even radiation safety were discussed with the keyword of "INTERFACE". More than 200 Papers were presented in the meeting and 72 contributed papers are compiled in the proceedings.
Ozu, Akira; Takase, Misao*; Haruyama, Mitsuo; Kurata, Noritaka*; Kobayashi, Nozomi*; Kureta, Masatoshi; Nakamura, Tatsuya; To, Kentaro; Sakasai, Kaoru; Suzuki, Hiroyuki; et al.
Nuclear Instruments and Methods in Physics Research A, 798, p.62 - 69, 2015/10
The light transport properties of scintillator light inside alternative He-3 neutron detector modules using scintillator sheets have been investigated by a ray-tracing simulation code. The detector module consists of a light-reflecting tube, a thin rectangular ceramic scintillator sheet laminated on a glass plate, and two photo-multiplier tubes (PMTs) mounted at both ends of the detector tube. The light induced on the surface of the scintillator sheet via nuclear interaction between the scintillator and neutrons are detected by the two PMTs. The light output of various detector modules in which the scintillator sheets are installed with several different arrangements were examined and evaluated in comparison with experimental results. The results derived from the simulation reveal that the light transport property is strongly dependent on the arrangement of the scintillator sheet inside the tube and the shape of the tube.
Sakai, Kenji; Oku, Takayuki; Hayashida, Hirotoshi*; Kira, Hiroshi*; Hiroi, Kosuke; Ino, Takashi*; Oyama, Kenji*; Okawara, Manabu*; Kakurai, Kazuhisa; Shinohara, Takenao; et al.
JPS Conference Proceedings (Internet), 8, p.036015_1 - 036015_6, 2015/09
The polarized He filter, which polarizes neutrons due to a large neutron absorption cross section of He with strong spin selectivity, becomes a convenient neutron spin filter (NSF) because it is operated immediately after its installation in beam lines without any neutron beam adjustments. For realizing such the NSF, a nuclear magnetic resonance (NMR) system is indispensable for monitoring He nuclear spin polarization of the NSF. We have developed the flexible NMR system based on adiabatic fast passage (AFP) and pulse NMR methods by using their complementary features. In comparing with the values of obtained by neutron transmission measurement at the beam line 10 of the J-PARC, we measured the correlations between the AFP and pulse NMR signals as changing condition of temperature, amplitude and applying period of the radio frequency field for the pulse NMR, and so on. As the results, we confirmed that our system would function enough as the monitor.
Sakai, Kenji; Oku, Takayuki; Hayashida, Hirotoshi; Kira, Hiroshi*; Shinohara, Takenao; Oikawa, Kenichi; Harada, Masahide; Kakurai, Kazuhisa; Aizawa, Kazuya; Arai, Masatoshi; et al.
Journal of Physics; Conference Series, 528, p.012016_1 - 012016_7, 2014/07
In polarized neutron experiments, it is interested in expanding measurable neutron energy region up to epithermal neutrons. For realizing this situation, a Polarized He Spin Flipper (PHSF) has a key role because it can polarize from cold to epithermal neutrons, and flip neutron spins by flipping the He nuclear spin direction. We have developed the portable PHSF consisting of a cylindrical glass cell filled with He gas which is installed a solenoid coil of 20 cm in diameter and 30 cm long. After polarizing the He gas by irradiating a laser light based on a SEOP technique, the PHSF is brought by hands to experimental areas with kept its polarization. We carried out the feasibility test on our portable PHSF in the MLF of J-PARC and demonstrated it worked well by evaluating flipping ratios of polarized neutrons and attempting to visualize magnetic fields generated by sample coils.
Kiriyama, Hiromitsu; Mori, Michiaki; Suzuki, Masayuki*; Daito, Izuru*; Okada, Hajime; Ochi, Yoshihiro; Tanaka, Momoko; Sato, Masatoshi*; Tamaoki, Yoshinori*; Yoshii, Takehiro*; et al.
Reza Kenkyu, 42(6), p.441 - 447, 2014/06
We describe three specific high power laser systems that are being developed in our laboratory for many applications in high field science, nonlinear optics and material processing. We report on a femtosecond petawatt-class Ti:sapphire chirped-pulse amplification laser system that can produce a pulse energy of 20 J of 40 fs pulse duration, a picosecond high intensity Yb:YAG chirped-pulse amplification laser system that can generate a pulse energy of 100 mJ of 0.5 ps pulse duration, and a nanosecond high repetition rate Nd:YAG laser system that can provide an average power of 360 W with a pulse duration of 30 ns delivered at a 1 kHz repetition rate. We discuss the basic design aspects and present the results from our experimental investigations of these laser systems.
Nakamura, Tatsuya; Ozu, Akira; To, Kentaro; Sakasai, Kaoru; Suzuki, Hiroyuki; Honda, Katsunori; Birumachi, Atsushi; Ebine, Masumi; Yamagishi, Hideshi*; Takase, Misao; et al.
Nuclear Instruments and Methods in Physics Research A, 763, p.340 - 346, 2014/05
A neutron-sensitive ZnS/BO ceramic scintillator detector was developed as an alternative to a He-gas-based detector for use in a plutonium canister assay system. The detector has a modular structure, with a flat ZnS/BOceramic scintillator strip that is installed diagonally inside a light-reflecting aluminium case with a square cross section. The prototype detectors, which have a neutron-sensitive area of 30 mm 250 mm, exhibited a sensitivity of 21.7-23.4 0.1 cpsnv for thermal neutrons, a Cs -ray sensitivity of 1.1-1.9 0.2 10 and a count variation of less than 6% over the detector length. A trial experiment revealed a temperature coefficient of less than -0.24 0.05% / C over the temperature range of 20-50C.
Iida, Kazuki*; Ikeuchi, Kazuhiko*; Ishikado, Motoyuki*; Suzuki, Junichi; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Arai, Masatoshi
JPS Conference Proceedings (Internet), 1, p.014016_1 - 014016_4, 2014/03
Nakamura, Mitsutaka; Kambara, Wataru; Krist, T.*; Shinohara, Takenao; Ikeuchi, Kazuhiko*; Arai, Masatoshi; Kajimoto, Ryoichi; Nakajima, Kenji; Tanaka, Hiromichi; Suzuki, Junichi*; et al.
Nuclear Instruments and Methods in Physics Research A, 737, p.142 - 147, 2014/02
The efficiency of inelastic neutron scattering measurements using a chopper spectrometer can be markedly improved by utilizing multiple incident energies (Multi-Ei method). However, in conventional chopper systems, optimization of the experimental condition for all incident energies is absolutely impossible. We developed a new Fermi chopper with a supermirror-coated slit package in order to overcome the problem and experimentally demonstrated that the full optimization of the experimental condition for multiple incident energies is nearly achieved.
Ozu, Akira; Takase, Misao*; Kurata, Noritaka*; Kobayashi, Nozomi*; Tobita, Hiroshi; Haruyama, Mitsuo; Kureta, Masatoshi; Nakamura, Tatsuya; Suzuki, Hiroyuki; To, Kentaro; et al.
Proceedings of 2014 IEEE Nuclear Science Symposium and Medical Imaging Conference; 21st International Symposium on Room-Temperature Semiconductor X-ray and -ray detectors (NSS/MIC 2014), 5 Pages, 2014/00
In Japan Atomic Energy Agency, the helium-3 alternative neutron detector using ceramic scintillators for nuclear safeguards is under development with the support of the government. The alternative detector module consists of four components: an aluminum regular square tube, a light reflecting foil put on the inner surface of the square tube, a rectangular scintillator sheet sintered on a glass plate, and two PMTs provided at both ends of the tube. The scintillator sheet is fit on the diagonal inside the square tube. The light transport property of scintillator lights inside the tube influences on the fundamental performance of the alternative detector. Therefore, the properties of the lights emitted on the surface of the scintillator sheet and scintillation lights passing through the glass plate to the PMTs in several arrangements of the scintillator in the tubes were investigated with a ray-tracing simulation. The results are described in comparison with the experimental results.
Tokunaga, Tomonori*; Watanabe, Hideo*; Yoshida, Naoaki*; Nagasaka, Takuya*; Kasada, Ryuta*; Lee, Y.-J.*; Kimura, Akihiko*; Tokitani, Masayuki*; Mitsuhara, Masatoshi*; Hinoki, Tatsuya*; et al.
Journal of Nuclear Materials, 442(1-3), p.S287 - S291, 2013/11
Nakamura, Tatsuya; To, Kentaro; Sakasai, Kaoru; Suzuki, Hiroyuki; Soyama, Kazuhiko; Kureta, Masatoshi; Ozu, Akira; Takase, Misao; Nakamura, Hironobu; Seya, Michio
Proceedings of INMM 54th Annual Meeting (CD-ROM), 8 Pages, 2013/07
We have developed a neutron detector by using ZnS/BO ceramic scintillator for nuclear safeguards NDA systems. The detector has a simple structure where ZnS/BO ceramic scintillator is implemented in the light reflecting case and two PMTs are connected at either end of it. The ZnS/BO ceramic scintillator was originally developed for a two-dimensional neutron detector in the Japan Proton Accelerator Research Complex in Materials and Life Science Experimental Facility. No organic binder material is used in the scintillator, which makes it suitable to a detector operating under -ray irradiation over a long period of time. A neutron absorption probability can be increased by installing two scintillator strips in cross arrangement. In the presentation present status of detector development including detector design, detection system and experimental results measured with a prototype detector will be presented.
Arai, Masatoshi; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Nakajima, Kenji; Shibata, Kaoru; Takahashi, Nobuaki; Suzuki, Junichi*; Takata, Shinichi; Yamada, Takeshi*; et al.
Journal of the Physical Society of Japan, 82(Suppl.A), p.SA024_1 - SA024_14, 2013/01
The paper describes developments of neutron scattering instruments in J-PARC neutron facility, which is a short pulse spallation source operated at a repetition rate 25 Hz and has a proton power 1 MW. New concept has been adopted to utilize high intensity coupled moderator even for a high resolution inelastic scattering instruments by taking a pulse shaping chopper system. Advanced technique has been also realized by taking an ability of event-recording system altogether with an improvement of a chopper system, realizing multi-Ei method. The paper also touches upon a general design concept for diffractometers in accordance with the source characteristics.
Teshigawara, Makoto; Kinoshita, Hidetaka; Wakui, Takashi; Meigo, Shinichiro; Seki, Masakazu; Harada, Masahide; Ito, Manabu; Suzuki, Toru; Ikezaki, Kiyomi; Maekawa, Fujio; et al.
JAEA-Technology 2012-024, 303 Pages, 2012/07
3 GeV Protons with 1 MW beam power are irradiated to mercury target of spallation neutron source in Materials and Life science Facility (MLF), which is one of facilities of J-PARC. Irradiated components, such as target container, moderator, reflector and proton beam window, are needed to replace periodically due to irradiation damage of high energy protons and neutrons. These used components are replaced remotely because of highly activated. Maintenance scenario was settled so as to handle these components. Required remote handling machines were designed and installed in hot cell and other room of the MLF. We performed remote handling tests by using actual components to confirm the design. We report results, such as replacement procedure, trouble and its solution, etc., for moderator, reflector and proton beam window in order to provide the handling of actual used components.
Suzuki, Masayuki; Kiriyama, Hiromitsu; Daito, Izuru; Okada, Hajime; Ochi, Yoshihiro; Sato, Masatoshi*; Yoshii, Takehiro*; Tamaoki, Yoshinori*; Maeda, Junya*; Matsuoka, Shinichi*; et al.
AIP Conference Proceedings 1465, p.53 - 57, 2012/07
We have reported hundred mJ level, femtosecond pulse duration with the high temporal contrast in an OPCPA/Yb:YAG ceramic thin disk laser system at 10 Hz repetition rate. At an input laser pulse energy of 3.8 mJ from the OPCPA preamplifer the output energy of 130 mJ with spectral bandwidth of 2.5 nm has been obtained from multipass Yb:YAG ceramic thin disk amplifier, and the optical efficiency from LD energy to amplified laser pulse is 9.6%. The recompressed laser pulse duration was measured to be 450 fs. Because the compressor efficiency exceeds 73% the compressed pulse energy can potentially be as high as 95 mJ. The contrast level of this laser pulse was measured to be less than 7.210 at -150 ps. This novel laser system after further amplification using additional amplifiers can be useful for the laser-driven proton acceleration in future.