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Watanabe, Kenichi*; Sugai, Yusuke*; Hasegawa, Sota*; Tanaka, Seishiro*; Hitomi, Keitaro*; Nogami, Mitsuhiro*; Shinohara, Takenao; Su, Y. H.; Parker, J. D.*; Kockelmann, W.*
Scientific Reports (Internet), 14, p.25224_1 - 25224_13, 2024/10
Times Cited Count：1 Percentile：13.54(Multidisciplinary Sciences)
gamma-ray imager using detector response patternsKitayama, Yoshiharu; Nogami, Mitsuhiro*; Hitomi, Keitaro*
Japanese Journal of Applied Physics, 63(7), p.076502_1 - 076502_8, 2024/07
Times Cited Count：0 Percentile：0.00(Physics, Applied)We constructed a gamma-ray imager that estimates the distribution of gamma-ray sources based on the response patterns of multiple gamma-ray detectors randomly positioned in three-dimensional space. The Coded Cube Camera for Gamma-ray (C3G), comprising eight GAGG (Ce) scintillator and eighteen lead cubes is housed in a cubical casing with an 86 mm edge length and weighs approximately 600 g. Results of the 4 imaging experiment confirmed the feasibility of imaging a 10 MBq 
Cs source located 3 m away with an angular uncertainty of 5
within a 10 min measurement. C3G operates with only eight channels, instead of the hundreds needed by a typical imager, offering a simplified circuit and reconstruction algorithm, thereby achieving a cost-effective and reliable system. With its compact and lightweight design, 4 field of view, and high angular uncertainty, this technology is expected to find extensive applications in astronomy, medicine, nuclear security, and decommissioning projects.
Kitayama, Yoshiharu; Nogami, Mitsuhiro*; Hitomi, Keitaro*
Japanese Journal of Applied Physics, 63(3), p.032005_1 - 032005_6, 2024/03
Times Cited Count：1 Percentile：11.69(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.
Watanabe, Kenichi*; Sugai, Yusuke*; Hasegawa, Sota*; Hitomi, Keitaro*; Nogami, Mitsuhiro*; Shinohara, Takenao; Su, Y. H.; Parker, J. D.*; Kockelmann, W.*
Sensors and Materials, 36(1), p.149 - 154, 2024/01
Times Cited Count：2 Percentile：28.23(Instruments & Instrumentation)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 3
33 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.
-P silica-based absorbentIto, Tatsuya; Kim, S.-Y.*; Xu, Y.*; Hitomi, Keitaro*; Ishii, Keizo*; Nagaishi, Ryuji; Kimura, Takaumi
Separation Science and Technology, 48(17), p.2616 - 2625, 2013/10
Times Cited Count：16 Percentile：46.78(Chemistry, Multidisciplinary)As fundamental research for separation of platinum group metals (PGMs) from high level liquid waste (HLLW) by macroporous silica-based adsorbent, (MOTDGA-TOA)/SiO-P adsorbent was prepared by impregnation of N,N'-dimethyl-N,N'-di-noctyl-thiodiglycolamide (MOTDGA) and Tri-n-octylamine (TOA) into silica/polymer composite support (SiO-P). The adsorption behavior of Ru(III), Rh(III), and Pd(II) in simulated HLLW onto the adsorbent were investigated by the batch method to obtain their corresponding equilibrium and kinetic data. The adsorbent showed strong adsorption for Pd(II) and the adsorption reached equilibrium within 2 hr. In addition, the use of both MOTDGA and TOA improved adsorption of Ru(III) and Rh(III) better than individual use of them. The adsorptions of Ru(III), Rh(III), and Pd(II) followed the Langmuir adsorption model, and were found to be controlled by the chemisorption mechanism.
Kitayama, Yoshiharu; Nogami, Mitsuhiro*; Hitomi, Keitaro*
no journal, ,
no abstracts in English
Hayashi, Hiroko*; Kido, Hiroko*; Kurosawa, Ryohei*; Sone, Koichiro*; Nogami, Mitsuhiro*; Kitayama, Yoshiharu; Hitomi, Keitaro*; Torii, Tatsuo*
no journal, ,
no abstracts in English
Nogami, Mitsuhiro*; Kitayama, Yoshiharu; Hitomi, Keitaro*
no journal, ,
no abstracts in English
Kitayama, Yoshiharu; Nogami, Mitsuhiro*; Hitomi, Keitaro*
no journal, ,
no abstracts in English
Ito, Tatsuya; Kim, S.-Y.*; Xu, Y.*; Hitomi, Keitaro*; Ishii, Keizo*; Nagaishi, Ryuji; Kimura, Takaumi
no journal, ,
no abstracts in English
-P and (MOTDGA-TOA)/SiO-PIto, Tatsuya; Kim, S.-Y.*; Xu, Y.*; Hitomi, Keitaro*; Ishii, Keizo*; Nagaishi, Ryuji; Kimura, Takaumi
no journal, ,
no abstracts in English
Maeda, Shigetaka; Nogami, Mitsuhiro*; Ito, Chikara; Watanabe, Kenichi*; Hitomi, Keitaro*
no journal, ,
A portable high-resolution gamma-ray spectrometer for nuclear facilities is developing. The research plan will be outlined, and the applicability to OLGM for fast reactor fuel failure detection and the required performance will be reported.
Nogami, Mitsuhiro*; Hitomi, Keitaro*; Ito, Chikara; Tsubakiyama, Kunimi*; Watanabe, Kenichi*; Maeda, Shigetaka
no journal, ,
While many studies have been conducted on improving energy resolution and increasing the volume of TlBr detectors, little evaluation has been made on long-term stability. Therefore, in this study, we evaluated the long-term stability of the TlBr detector when it was operated continuously for about 2000 hours, assuming application to an actual nuclear power plant.
Watanabe, Kenichi*; Tsubakiyama, Kunimi*; Hitomi, Keitaro*; Nogami, Mitsuhiro*; Ito, Chikara; Maeda, Shigetaka
no journal, ,
The crystallinity of TlBr crystals was evaluated using the neutron Bragg dip imaging method, which is one of the neutral diffraction methods, as a part of the study for improving the detector performance.
Watanabe, Kenichi*; Hitomi, Keitaro*; Nogami, Mitsuhiro*; Maeda, Shigetaka; Ito, Chikara; Tanno, Takashi; Onabe, Hideaki*
no journal, ,
TlBr is a compound semiconductor with a high atomic number, high density and a wide bandgap, and is being developed as a gamma-ray detector material that can be operated at room temperature and has high detection efficiency. There is neutron diffraction in order to establish a crystal quality evaluation method for improving the yield in device fabrication, but the facilities that can be implemented are limited to large facilities such as J-PARC. The Electron Backscatter Diffraction (EBSD) image, which is one of the electron beam diffractions, can be obtained with an electron microscope, but only the information on the crystal surface can be obtained. In this study, the crystal orientation image was acquired for the TlBr crystal by neutron Bragg dip imaging, which is one of the neutron diffractions, and EBSD. By comparing both images, the applicability to a simple EBSD crystal quality evaluation method was examined.
Kitayama, Yoshiharu; Nogami, Mitsuhiro*; Hitomi, Keitaro*
no journal, ,
Watanabe, Kenichi*; Hitomi, Keitaro*; Nogami, Mitsuhiro*; Maeda, Shigetaka; Onabe, Hideaki*
no journal, ,
Thallium bromide (TlBr) is a compound semiconductor attractive for gamma-ray spectrometers. TlBr detectors have shown excellent energy resolution, however, these results were obtained from relatively small crystal detectors. The next phase of TlBr development is to increase the detector size and improve the yield rate of detector production. So far, we have evaluated crystal quality of TlBr by using the neutron Bragg-dip imaging, which is one of the neutron diffraction techniques. In this study, we prepared a large TlBr crystal wafer with a diameter and thickness of 50 mm and 12 mm, respectively. We evaluated the quality of the large crystal by the neutron Bragg-dip imaging. The center region of the large TlBr crystal confirmed to be uniform and well-aligned. As a future work, we will evaluate the electric properties, such as the mobility-lifetime product, at various positions in this large crystal.
Kitayama, Yoshiharu; Nogami, Mitsuhiro*; Hitomi, Keitaro*
no journal, ,
no abstracts in English
Nogami, Mitsuhiro*; Kitayama, Yoshiharu; Hitomi, Keitaro*; Baduy, N.*; Tamura, Yusuke*; Kawata, Ryutaro*; Kaneko, Shinichiro*; Takada, Eiji*; Torii, Tatsuo*
no journal, ,
no abstracts in English
