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Kitayama, Yoshiharu; Nogami, Mitsuhiro*; Hitomi, Keitaro*
Japanese Journal of Applied Physics, 63(3), p.032005_1 - 032005_6, 2024/03
Times Cited Count:0 Percentile:0.01(Physics, Applied)We introduce a novel gamma-ray imaging technique that uses detector response patterns. This method employs multiple shielding cubes randomly positioned in a three-dimensional configuration. Within the volume defined by these cubes, a unique gamma-ray flux pattern is formed based on the incidence direction of the gamma rays. This pattern can be measured using the responses of several scintillator cubes. By pre-measuring the detector response pattern and incidence direction of the gamma rays, the incidence direction can be estimated using an unfolding technique. Simulations were performed using a Cs point source. Our results show that a 10 MBq Cs source, located 3 m away from the imager, can be imaged with an angular resolution close to 10. These findings suggest that our new method is comparable to existing gamma-ray imaging techniques. Potential applications of this imaging method include nuclear power plant decommissioning, nuclear medicine, security, and astronomy.
Kawahara, Rika*; Ochi, Kotaro; Yamaguchi, Katsuhiko*; Torii, Tatsuo*
Hoshasen (Internet), 48(2), p.43 - 48, 2023/04
The accident at the Fukushima Daiichi NPP resulted in a large amount of radioactive material being dispersed into the surrounding environment. It is important to understand the radiation distribution in the area, which is still located in the difficult-to-return zone. In this study, a Compton camera and an optical camera were combined to produce a three-dimensional distribution map of source locations and their intensities. Two locations in the difficult-to-return zone (Okuma town) were surveyed: a park parking lot and the area around a private house. The distribution of air dose rates was determined by measurements with a survey meter with a wand-type GPS (Gamma Plotter H manufactured by Nippon Radiation Engineering Co. Measurements were taken with a Compton camera (H420, H3D, USA) at several different positions and angles towards the hotspots. The software (Application Programming Interface Example) allowed real-time confirmation of the radiation incident information (incident time, energy, x, y, z) obtained by the Compton camera. By photographing hotspots in high-dose areas from different positions and angles, the location of the radiation sources and their spatial extent could be confirmed.
Nakae, Masanori*; Matsuyama, Tsugufumi*; Murakami, Masashi; Yoshida, Yukihiko; Machida, Masahiko; Tsuji, Koichi*
Advances in X-Ray Chemical Analysis, Japan, 54, p.89 - 99, 2023/03
Fundamental research on X-ray absorption imaging for elemental identification was studied. A secondary target was applied to obtain X-ray absorption images above and below the X-ray absorption edge of the target element. X-rays from an X-ray tube were irradiated to the secondary target, where the characteristic X-rays were emitted that were irradiated to the sample. X-ray absorption images were acquired with an exposure time of a few seconds with an X-ray camera. In this technique, it is difficult to change the energy of X-rays as we want, however we can apply this technique for imaging the specific element. Metal foil sample composed of Al, Cu, and Ni was analyzed. To obtain an X-ray elemental image of Ni, two X-ray absorption images were taken using the X-rays above and below the Ni K-edge. X-rays of Cu K and Zn K were prepared by using Cu and Zn plates as the secondary target. Finally, the Ni elemental image was obtained by subtracting two images. Furthermore, the X-ray camera had a function of setting critical energies for imaging, thus it was demonstrated that an X-ray elemental image of Ni was obtained using a single secondary target without changing the secondary target.
Kitayama, Yoshiharu; Nogami, Mitsuhiro*; Hitomi, Keitaro*
KEK Proceedings 2022-3, p.46 - 53, 2023/01
The position of a streetlight can be predicted from the direction and shape of one's shadow projected on the street at night by the light of the streetlight. The application of this idea to gamma-ray imagers is known as coded aperture. In this study, we proposed the Coded Cube Camera - POrtable (C3PO), which has a three-dimensional shielding and scintillator crystal arrangement, and is composed of lead, scintillator, and depletion cubes randomly arranged in a 333 Rurik's cube shape, with each. The output of each scintillator produces a three-dimensional shadow pattern, which is returned to the source direction distribution by unfolding. In this study, we investigated the characteristics and feasibility of the system by simulation using Geant 4.
Sato, Yuki
Isotope News, (781), p.19 - 23, 2022/06
no abstracts in English
Sato, Yuki
Kensa Gijutsu, 27(5), p.9 - 15, 2022/05
no abstracts in English
Shikaze, Yoshiaki; Shimazoe, Kenji*
Journal of Nuclear Science and Technology, 59(1), p.44 - 54, 2022/01
Times Cited Count:3 Percentile:44.61(Nuclear Science & Technology)A Compton camera system for use on an unmanned helicopter was previously developed for characterizing the distribution of radioactive materials in highly contaminated areas. For this study, a small camera, a laser distance meter, an attitude angles sensor, temperature sensors, and real-time monitoring software were equipped to the Compton camera system to better measure flight parameters and to more precisely detect hot spot locations. To confirm if detection results were improved by the modifications, measurements were taken from hovering and programmed flights over a field in Okuma, Fukushima Prefecture (Japan). Ambient dose equivalent rate distributions at ground level were obtained by processing the flight data, then compared against measurements taken at ground level on foot using a survey meter. For one hovering flight, the correlation between the datasets was improved by selecting a period of stable flight position and attitude, and by restricting the deviation of the attitude angles. Between 6.0%-7.6% improvement in the position resolution was achieved by using the data from stable flight periods, even when using 1 minute data windows. The precision of hot spot detections and ambient dose equivalent rate distributions obtained from the Compton camera were thus improved by the aforementioned modifications to the system.
Sato, Yuki; Torii, Tatsuo
Nuclear Technology, 206(7), p.v - xvi, 2020/07
Times Cited Count:2 Percentile:66.67(Nuclear Science & Technology)Takeuchi, Tomoaki; Otsuka, Noriaki; Nakano, Hiroko; Iida, Tatsuya*; Ozawa, Osamu*; Shibagaki, Taro*; Komanome, Hirohisa*; Tsuchiya, Kunihiko
QST-M-16; QST Takasaki Annual Report 2017, P. 67, 2019/03
no abstracts in English
Watanabe, Takashi*; Ozawa, Osamu*; Takeuchi, Tomoaki
Denki Gakkai-Shi, 138(8), p.529 - 534, 2018/08
no abstracts in English
Sato, Yuki; Torii, Tatsuo
Isotope News, (757), p.44 - 47, 2018/06
no abstracts in English
Watanabe, Takashi*; Takeuchi, Tomoaki; Ozawa, Osamu*; Komanome, Hirohisa*; Akahori, Tomoyuki*; Tsuchiya, Kunihiko
Proceedings of 2017 International Image Sensor Workshop (IISW 2017) (Internet), p.206 - 209, 2017/05
no abstracts in English
Takeuchi, Tomoaki; Tsuchiya, Kunihiko; Komanome, Hirohisa*; Miura, Kuniaki*; Ishihara, Masahiro
Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 6 Pages, 2017/04
After the accident at the Fukushima Dai-ichi (1F) Nuclear Power Plant (NPP), the Japanese Government referred to "Enhancement of instrumentation to identify the status of the reactors and PCVs", in the report of Japanese government to the IAEA ministerial conference in June 2011. In response to these provisions, a research and development of a monitoring system for NPPs situations during severe accidents started in November 2012. The objectives of the R&D are composed of radiation-resistant monitoring camera, radiation-resistant in-water transmission system, and heat-resistant signal cable. For all the three objectives, the elemental technologies have been already developed and now trial system are being fabricated and tested under simulated conditions of severe accidents. The results will enable us to determine the basic specifications of the systems and to provide the information about application limits for users.
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
Times Cited Count:37 Percentile:96.39(Nuclear Science & Technology)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).
Okuda, Eiji; Sasaki, Jun; Suzuki, Nobuhiro; Takamatsu, Misao; Nagai, Akinori
JAEA-Technology 2016-017, 20 Pages, 2016/07
In-Vessel Observation (IVO) techniques for Sodium Cooled Fast Reactors (SFRs) in service are important for confirming their safety and integrity. Since IVO equipment for an SFR has to be designed to tolerate the severe conditions (high temperature, high radiation dose and limited access route), fiberscopes used to be used in previous IVO for SFRs. However, in order to attain an IVO with higher quality and resolution, IVO using a radiation resistant camera was conducted in the fast experimental reactor Joyo and obtained some results. The demonstration results provided valuable insights for use in further improving and verifying IVO techniques in SFRs.
Takeuchi, Tomoaki; Otsuka, Noriaki; Shibagaki, Taro*; Komanome, Hirohisa*; Ueno, Shunji*; Tsuchiya, Kunihiko
Nihon Hozen Gakkai Dai-13-Kai Gakujutsu Koenkai Yoshishu, p.379 - 386, 2016/07
no abstracts in English
Takeuchi, Tomoaki; Otsuka, Noriaki; Tsuchiya, Kunihiko; Tanaka, Shigeo*; Ozawa, Osamu*; Komanome, Hirohisa*; Watanabe, Takashi*; Ueno, Shunji*
Nihon Hozen Gakkai Dai-13-Kai Gakujutsu Koenkai Yoshishu, p.391 - 394, 2016/07
no abstracts in English
Tsuchiya, Kunihiko; Takeuchi, Tomoaki; Komanome, Hirohisa*; Miura, Kuniaki*; Araki, Masanori; Ishihara, Masahiro
Nihon Hozen Gakkai Dai-13-Kai Gakujutsu Koenkai Yoshishu, p.375 - 378, 2016/07
no abstracts in English
Chiba, Atsuya; Ishii, Yasuyuki; Tajima, Satoshi
JAERI-Review 2003-033, TIARA Annual Report 2002, p.327 - 329, 2003/11
no abstracts in English
Ochi, Yoshihiro; Golovkin, I.*; Mancini, R.*; Uschmann, I.*; Sunahara, Atsushi*; Nishimura, Hiroaki*; Fujita, Kazuhisa*; Louis, S.*; Nakai, Mitsuo*; Shiraga, Hiroyuki*; et al.
Review of Scientific Instruments, 74(3), p.1683 - 1687, 2003/03
Times Cited Count:10 Percentile:49.35(Instruments & Instrumentation)no abstracts in English