Simulation study of a novel compact 4 gamma-ray imager

Kitayama, Yoshiharu  ; Nogami, Mitsuhiro*; Hitomi, Keitaro*

We have been developing a novel, compact, and lightweight gamma-ray imager, the Coded Cube Camera for Gamma-ray (C3G), composed of cube-shaped detectors and lead shields arranged in a 3D structure. This study presents a simulation-based preliminary evaluation of an improved version of the current C3G design, which is scheduled for fabrication in the near future. The system consists of 24 detector cubes (10 mm GAGG: Ce scintillators with SiPMs) and 40 lead cubes of the same size, arranged in a lattice. It estimates gamma-ray incident directions over 4 steradians using variations in the detector response pattern depending on irradiation angle, enabling 4 imaging with a small number of detectors. Simulations were conducted for Co (122 keV), Cs (662 keV), and Co (1333 keV) sources (10 MBq), placed 3 meters from the C3G with a 100-minute acquisition time. High-quality imaging was confirmed for all three tested gamma-ray energies, although a tendency for decreased imaging accuracy at higher energies was observed. Two-source separation tests showed that two sources 20 degrees apart were clearly resolved for all three isotopes evaluated in this study, corresponding to 50 cm resolution at 3 meters. At 122 keV, better resolution was achieved with a modified geometry using only scintillator cubes, indicating that lead shielding may be redundant at lower energies. These results confirm that C3G enables 4 imaging across a wide energy range. Further performance improvements are expected through optimization of shielding materials and layout. With its wide field of view and high resolution using a small number of detectors, C3G is highly promising for applications in space observation, medical imaging, nuclear decommissioning, and nuclear security.