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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：0 Percentile：0.00(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：27.39(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：53.92(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.
北山 佳治
人見 啓太朗*; 野上 光博*
JP, 2023-007015 
Patent licensing information
【課題】視野が広く、放射線エネルギーの適用範囲が広く、且つ、小型軽量化を図ることが可能な新しい放射線検出装置を提供することを目的とする。 【解決手段】放射線検出装置1は、放射線を検出する複数の検出素子12が3次元的に配置された検出素子群11を備える放射線検出装置である。検出素子群11の構造は、任意の仮想面S上に検出素子12が敷き詰められた仮想検出素子群から任意の位置の検出素子12を取り除いて形成された空乏13を有する構造である。空乏13は、任意の方向に沿って配置された一の検出素子12A及び他の検出素子12Bの各検出値の差分が、当該方向を入射方向とする放射線が入射する場合と当該方向の逆方向を入射方向とする放射線が入射する場合とにおいて、異なる値を示す位置に設けられる。
北山 佳治
人見 啓太朗*; 野上 光博*
JP, 18/410450 Patent licensing information
A radiation detection device is provided that is wide in visual field, wide in application range of radiation energy, and which is smaller and lighter in weight as compared to other devices. The device includes a detecting element group has a plurality of detecting elements that detect radiation are three-dimensionally arranged. The detecting element group has a structure with a depletion formed by removing the detecting element at any position from a virtual detecting element group in which the detecting elements are laid out on any virtual surface. The depletion is provided at a position at which a difference of detected values between one detecting element and another detecting element arranged along any direction exhibits different values in a case where the radiation having the direction as an incident direction enters and a case where the radiation having an opposite direction of the direction as an incident direction enters.
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.
Kitayama, Yoshiharu; Nogami, Mitsuhiro*; Hitomi, Keitaro*
no journal, ,
Kitayama, Yoshiharu; Nogami, Mitsuhiro*; Hitomi, Keitaro*
no journal, ,
no abstracts in English
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
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
Kitayama, Yoshiharu; Nogami, Mitsuhiro*; Hitomi, Keitaro*
no journal, ,
no abstracts in English
Watanabe, Kenichi*; Hitomi, Keitaro*; Nogami, Mitsuhiro*; Maeda, Shigetaka; Onabe, Hideaki*
no journal, ,
TlBr is a compound semiconductor with a high atomic number and density, and a wide bandgap. TlBr detector is being developed as a gamma-ray detector material that can operate at room temperature and has high detection efficiency. The current issue is to improve the yield in device manufacturing, and it is required to establish a process that can stably manufacture high quality devices. The crystal growth process is one of the most important processes in producing a good quality detector, and it is very important to understand how crystals are grown. This time, we tried to obtain knowledge about crystal growth by observing the crystal orientation distribution in the crystal growth direction.
Nogami, Mitsuhiro*; Kitayama, Yoshiharu; Hitomi, Keitaro*; Takada, Eiji*; Torii, Tatsuo*; Ishii, Keizo*
no journal, ,
no abstracts in English
field of view gamma-ray imaging methodKitayama, Yoshiharu; Nogami, Mitsuhiro*; Hitomi, Keitaro*
no journal, ,
