A prototype of SiPM-based scintillator Compton camera with capacitive multiplexing readout

Abstract

Compton camera is capable of visualizing the distribution of radioactivity based on the Compton scattering kinematics, and can be applied in nuclear accident emergency response, radioactivity decontamination, homeland security and etc. A prototype of Compton camera has been constructed consisting of two 4 × 4 SiPM-Ce: GAGG scintillator arrays. The signals of a SiPM array were converted into 4 position-weighted outputs with capacitive network circuit and collected by a CAEN digitizer. Two-dimensional flood images and energy responses of two detector modules were obtained. The average energy resolution of single elements of the two detector modules was 6.6% FWHM at 662 keV. Imaging performance of the prototype camera was evaluated with a ¹³⁷Cs point source and a ²²Na point source. Efficiency of the prototype for the ¹³⁷Cs point source located right in front was measured to be 0.09%. The angular resolution of a ¹³⁷Cs point source placed right in front of the camera was 7.2° FWHM. Isotopic images of the two gamma-ray sources were obtained with spatial resolutions of 8.2° FWHM for ¹³⁷Cs and 8.8° FWHM for ²²Na.