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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.
field-of-view gamma-ray imagingKitayama, Yoshiharu
IEEE NPSS Newsletter (Internet), 4 Pages, 2024/06
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：46.22(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.
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.
Morishita, Yuki; Takasaki, Koji; Kitayama, Yoshiharu; Tagawa, Akihiro; Shibata, Takuya; Hoshi, Katsuya; Kaneko, Junichi*; Higuchi, Mikio*; Oura, Masatoshi*
Radiation Measurements, 160, p.106896_1 - 106896_10, 2023/01
Times Cited Count：8 Percentile：87.16(Nuclear Science & Technology)This study proposes a newly developed phoswich alpha/beta detector that can discriminate alpha and beta particles emitted from the alpha and beta contaminations in the FDNPS site. The phoswich alpha/beta detector is made up of two layers of scintillators that detect alpha and beta particles. The pulse shape discrimination (PSD) method was used to detect alpha particles in high beta particle and high gamma-ray (comparable to gamma-ray dose rate near the FDNPS reactor building) environments. Due to a 23.3% full width at half maximum (FWHM) energy resolution for alpha particles, the detector can be used to distinguish between nuclear fuel materials such as plutonium and its radon progeny (Po-214). Moreover, the detector could distinguish alpha particles from Cs gamma rays with a dose rate background up to 9.0 mSv/h. It is the first to demonstrate that the developed phoswich detector can be used to discriminate and measure alpha and beta particles of the actual contaminated FDNPS samples.
Kitayama, Yoshiharu
Gamma Ray Imaging; Technology and Applications, p.165 - 179, 2023/00
A gamma-ray imager is a powerful tool for visualizing the distribution of radioactive materials. Recently, it has been applied to the decommissioning site of the Fukushima Daiichi Nuclear Power Station. At the decommissioning site, an imager compact, lightweight, and capable of quantitative evaluation of radioactivity is demanded. The Gamma-ray Imager using Small-Angle Scattering (GISAS) was proposed as a gamma-ray imager that meets all these requirements. GISAS consists of several shield-free directional gamma-ray detectors that detect only small-angle Compton scattering. Simulations and experiments verified the feasibility of the shield-free directional gamma-ray detectors. The shield-free directional gamma-ray detector consists of a scatterer that detects small-angle Compton scattering and an absorber that detects the scattered gamma rays. By setting an appropriate energy window for each detector, only scattering events that can be considered almost straightforward are detected. Through simulations and experiments, we have confirmed that using a silicon drift detector as the scatterer and a Gd3Al2Ga3O12 scintillator as the absorber, we can detect only small-angle Compton scattering events and obtain directionality for 662 keV gamma rays.
Kitayama, Yoshiharu; Terasaka, Yuta; Sato, Yuki; Torii, Tatsuo
Journal of Nuclear Engineering and Radiation Science, 7(4), p.042006_1 - 042006_7, 2021/10
Kitayama, Yoshiharu; Terasaka, Yuta; Sato, Yuki; Torii, Tatsuo
Proceedings of International Youth Nuclear Congress 2020 (IYNC 2020) (Internet), 4 Pages, 2020/05
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.
Kitayama, Yoshiharu; Nogami, Mitsuhiro*; Hitomi, Keitaro*
no journal, ,
no abstracts in English
Kitayama, Yoshiharu; Terasaka, Yuta; Sato, Yuki
no journal, ,
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
no journal, ,
no abstracts in English
Kitayama, Yoshiharu; Nogami, Mitsuhiro*; Hitomi, Keitaro*
no journal, ,
no abstracts in English
Kitayama, Yoshiharu; Terasaka, Yuta; Sato, Yuki
no journal, ,
We have developed a vehicle-mounted gamma-ray imaging system, iRIS-V. This system is capable of gamma-ray imaging around the vehicle and a car-borne survey similar to that of a monitoring car. This presentation will report the results of a car-borne survey of Route 35 in the difficult-to-return zone by iRIS-V and a gamma-ray imaging test around the entire vehicle using a Cs checking source.
Kitayama, Yoshiharu; Nogami, Mitsuhiro*; Hitomi, Keitaro*
no journal, ,
no abstracts in English
Kitayama, Yoshiharu; Terasaka, Yuta; Sato, Yuki; Torii, Tatsuo
no journal, ,
no abstracts in English
