Fujimori, Kosuke*; Kitaura, Mamoru*; Taira, Yoshitaka*; Fujimoto, Masaki*; Zen, H.*; Watanabe, Shinta*; Kamada, Kei*; Okano, Yasuaki*; Kato, Masahiro*; Hosaka, Masahito*; et al.
Applied Physics Express, 13(8), p.085505_1 - 085505_4, 2020/08
To clarify the existence of cation vacancies in Ce-doped GdAlGaO (Ce:GAGG) scintillators, we performed gamma-ray-induced positron annihilation lifetime spectroscopy (GiPALS). GiPAL spectra of GAGG and Ce:GAGG comprised two exponential decay components, which were assigned to positron annihilation at bulk and defect states. By an analogy with Ce:YAlO, the defect-related component was attributed to Al/Ga-O divacancy complexes. This component was weaker for Ce, Mg:GAGG, which correlated with the suppression of shallow electron traps responsible for phosphorescence. Oxygen vacancies were charge compensators for Al/Ga vacancies. The lifetime of the defect-related component was significantly changed by Mg co-doping. This was understood by considering aggregates of Mg ions at Al/Ga sites with oxygen vacancies, which resulted in the formation of vacancy clusters.
Tsuchiya, Harufumi; Koizumi, Mitsuo; Kitatani, Fumito; Harada, Hideo
Nuclear Instruments and Methods in Physics Research A, 932, p.16 - 26, 2019/07
Shikaze, Yoshiaki; Nishizawa, Yukiyasu; Sanada, Yukihisa; Torii, Tatsuo; Jiang, J.*; Shimazoe, Kenji*; Takahashi, Hiroyuki*; Yoshino, Masao*; Ito, Shigeki*; Endo, Takanori*; et al.
Journal of Nuclear Science and Technology, 53(12), p.1907 - 1918, 2016/12
The Compton camera was improved for use with the unmanned helicopter. Increase of the scintillator array from 44 to 88 and expanse of the distance between the two layers contributed to the improvements of detection efficiency and angular resolution, respectively. Measurements were performed over the riverbed of the Ukedo river of Namie town in Fukushima Prefecture. By programming of flight path and speed, the areas of 65 m 60 m and 65 m 180 m were measured during about 20 and 30 minutes, respectively. By the analysis the air dose rate maps at 1 m height were obtained precisely with the angular resolution corresponding to the position resolution of about 10 m from 10 m height. Hovering flights were executed over the hot spot areas for 10-20 minutes at 5-20 m height. By using the reconstruction software the -ray images including the hot spots were obtained with the angular resolution same as that evaluated in the laboratory (about 10).
Koizumi, Mitsuo; Sakasai, Kaoru; Kureta, Masatoshi; Nakamura, Hironobu
Nihon Genshiryoku Gakkai-Shi ATOMO, 58(11), p.642 - 646, 2016/11
no abstracts in English
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.
Nakamura, Hironobu; Mukai, Yasunobu; Tobita, Hiroshi; Nakamichi, Hideo; Ozu, Akira; Kureta, Masatoshi; Kurita, Tsutomu; Seya, Michio
Proceedings of 37th ESARDA Annual Meeting (Internet), p.45 - 53, 2015/08
JAEA conducted an R&D project to develop a new type of neutron detector using ZnS/BO ceramic scintillator (as an alternative neutron detector to He-3) with support of Japanese government. The design of the JAEAs alternative system (ASAS: Alternative Sample Assay System using ceramic scintillator tubes) refers basically to the INVS (INVentory Sample assay system) which is the passive type of neutron assay system equipped total 18 He-3 tubes and capable of measuring the small amount of Pu in the MOX powder or Pu nitrate solution in a vial for nuclear material accountancy and safeguards verification. In order to prove the alternative technology and the performance instead of He-3 detector, and to establish Pu measurement capability, JAEA developed and fabricated ASAS equipped 24 alternative ceramic scintillator tubes (which is equivalent to the same counting efficiency of INVS) and demonstrated. The demonstration activity implemented the confirmation of reproducibility about sample positioning, optimization of detector parameters, counting statistical uncertainty, stability check and figure of merit (FOM) using Cf check source and actual MOX powder in PCDF (Plutonium Conversion Development Facility). In addition, performance comparison between the current INVS and the ASAS was also implemented. In this paper, we present demonstration results with design information with Monte-Carlo simulation code (MCNP).
Seya, Michio; Naoi, Yosuke; Kobayashi, Naoki; Nakamura, Takahisa; Hajima, Ryoichi; Soyama, Kazuhiko; Kureta, Masatoshi; Nakamura, Hironobu; Harada, Hideo
Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-35-Kai Nenji Taikai Rombunshu (Internet), 9 Pages, 2015/01
The Integrated Support Center for Nuclear Non-proliferation and Nuclear Security (ISCN) of Japan Atomic Energy Agency (JAEA) has been conducting (based on collaborations with JAEA other centers) the following basic technology development programs of advanced non-destructive detection/measurement of nuclear material for nuclear security and nuclear non-proliferation. (1) The demonstration test of the Pu-NDA system for spent fuel assembly using PNAR and SINRD (JAEA/USDOE(LANL) collaboration, completed in JFY2013), (2) Basic development of NDA technologies using laser Compton scattered -rays (Demonstration of an intense mono-energetic -ray source), (3) Development of alternative to He-3 neutron detection technology, (4) Development of neutron resonance densitometry (JAEA/JRC collaboration)This paper introduces above programs.
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.
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.
Satoh, Daiki; Sato, Tatsuhiko; Endo, Akira; Matsufuji, Naruhiro*; Sato, Shinji*; Takada, Masashi*; Ishibashi, Kenji*
Nuclear Science Symposium Conference Record, 2005 IEEE, Vol.3, p.1288 - 1290, 2005/10
The response functions of a BC501A liquid organic scintillator have been measured for incidence of various charged particles to investigate the relationship between the kinetic energy of the charged particles and the light output of BC501A. The experiment was performed at Heavy-Ion Medical Accelerator in Chiba (HIMAC) utilizing spallation reactions by heavy ion bombardment on a graphite target. Charged particles incidental on BC501A were identified with the two-dimensional scatter plot of the time-of-flight and the light output. The light output of the BC501A scintillator was deduced as a function of the kinetic energy of the charged particles, and was compared with the semi-empirical formula. While the experimental data showed a good agreement with the formula for proton and deuteron, the data gave slightly larger values compared with the systematic trend for alpha particle.
Usami, Tsutomu; Moriyama, Kiyofumi; Nishikizawa, Tomotoshi; Nakamura, Hideo
JAERI-Tech 2005-028, 37 Pages, 2005/05
The steam explosion during a severe accident in a light water reactor, which may occur by the contact of molten core and coolant, has been known as a potential threat on the integrity of the containment vessel, and has been studied in the nuclear safety research field. Prediction of the intensity of steam explosions needs an understanding of the initial premixture. However, visual observation of the premixture in experiments is usually difficult due to the vapor generation. Thus, we investigated the possibility of a high-speed X-ray visualization with a 4500 f/s high speed video camera with an image-intensifier and three kinds of scintillator materials: CdWO, ZnS(Ag) and CsI(Tl). A modeled premixture consisted of metal objects and bubbles in a water vessel was used. The test result showed that the CsI(Tl) scintillator gave the best image quality among the three and the high-speed visualization at 4500 f/s was possible, though in the still picture which carried out one of the recorded picture, the picture became indistinct.
Satoh, Daiki; Sato, Tatsuhiko; Endo, Akira; Yamaguchi, Yasuhiro; Takada, Masashi*; Ishibashi, Kenji*
AIP Conference Proceedings 769, p.1680 - 1683, 2005/05
Response function of liquid organic scintillators is essential to derive the accurate neutron spectrum. Experimental data above 100 MeV, however, are very scarce. The existing Monte Carlo codes, SCINFUL and CECIL, are often used for estimation of the response function instead of the experimental data. These codes are known to reproduce well the response function for incidences below 100 MeV. Unfortunately, the codes are not applicable to the calculation in the higher energy region. In order to determine the response functions above 100 MeV, a new Monte Carlo code, designated as SCINFUL-QMD, has been developed. In the comparison with the experimental data up to 800 MeV, the validation of SCINFUL-QMD was confirmed. The results of SCINFUL-QMD agreed with the experimental data better than those of other calculation codes.
Satoh, Daiki; Sato, Tatsuhiko; Endo, Akira; Yamaguchi, Yasuhiro; Takada, Masashi*
NIRS-M-180, p.263 - 264, 2005/05
Response functions of NE213 liquid organic scintillator have been measured to develop a dose assessment method for high-energy neutrons. Spallation reactions by 800 MeV/u Si ions and 400 MeV/u C ions incident into thick carbon targets were utilized for the production of high-energy neutrons. Kinetic energies of neutrons were determined by the time-of-flight (TOF) method. -ray and charged particle events were eliminated from experimental data in off-line analysis. The measured response functions were used for validation of the simulation by the SCINFUL-QMD code, which is utilized for calculation of the G-function that converts the scintillator response to neutron dose. It was found from the results that SCINFUL-QMD has a good ability to reproduce the response functions.
Isobe, Mitsutaka*; Shinohara, Koji
Purazuma, Kaku Yugo Gakkai-Shi, 80(12), p.1036 - 1043, 2004/12
Escaping energetic ion diagnostics in magnetically confined plasma experiments are described in this lecture note. Experimental results from escaping energetic ion diagnostics in TFTR, JFT-2M, CHS and W7-AS are shown. In addition to mechanism of energetic ion loss from a viewpoint of particle orbit, effect of MHD activity on energetic particle transport is reviewed.
Ebine, Masumi; Katagiri, Masaki; Birumachi, Atsushi; Matsubayashi, Masahito; Sakasai, Kaoru; Sato, Setsuo*
Nuclear Instruments and Methods in Physics Research A, 529(1-3), p.429 - 432, 2004/08
no abstracts in English
Katagiri, Masaki; Sakasai, Kaoru; Matsubayashi, Masahito; Nakamura, Tatsuya; Kondo, Yasuhiro*; Chujo, Yoshiki*; Nanto, Hidehito*; Kojima, Takahiro*
Nuclear Instruments and Methods in Physics Research A, 529(1-3), p.274 - 279, 2004/08
no abstracts in English
Nuclear Instruments and Methods in Physics Research A, 529(1-3), p.254 - 259, 2004/08
no abstracts in English
Katagiri, Masaki; Sakasai, Kaoru; Matsubayashi, Masahito; Kojima, Takahiro*
Nuclear Instruments and Methods in Physics Research A, 529(1-3), p.317 - 320, 2004/08
no abstracts in English
Kojima, Takahiro*; Katagiri, Masaki; Tsutsui, Noriaki*; Imai, Koji*; Matsubayashi, Masahito; Sakasai, Kaoru
Nuclear Instruments and Methods in Physics Research A, 529(1-3), p.325 - 328, 2004/08
no abstracts in English
Kubota, Naoyoshi*; Katagiri, Masaki; Kamijo, Keiichi*; Nanto, Hidehito*
Nuclear Instruments and Methods in Physics Research A, 529(1-3), p.321 - 324, 2004/08
no abstracts in English