Portable Compton Imaging System with Ce:GAGG Crystals and Dynamic Time-over-Threshold Method

Abstract

After the Fukushima Daiichi Nuclear Power Plant accident on March 11th, 2011, Cs-137 and Cs-134 contamination have caused great concern. In our previous study, a portable Compton imaging system comprising 4 × 4 Ce-doped Gd3Al2Ga3O12 (Ce:GAGG) crystals coupled to 16 Si photomultipliers (SiPMs) and 16 avalanched photodiodes respectively, was developed, and contamination mapping using the developed Compton imaging system mounted on an unmanned helicopter was demonstrated in Fukushima. In this paper, a newly developed Compton imaging system with a larger detector volume is proposed. It consists of 8 × 8 Ce:GAGG crystals coupled to 64 SiPMs respectively. The energy resolution, angular resolution measure (ARM), and spatial resolution for several radioactive isotopes were investigated experimentally and reported.