Development of an omnidirectional Compton camera with enhanced energy resolution for radioactive source localization

Abstract: Abstract: For radioactive source localization, traditional Compton cameras are limited by the imaging field of view and low detection efficiency, resulting in slow response in complex environments. To address the limitations in the azimuthal sensitivity of conventional dual-layer scintillator detectors and the sensitive volume of semiconductor detectors, this study proposes an omnidirectional Compton camera based on four-layer scintillator detectors with a square ring-shaped structure. This imaging system features omnidirectional sensitivity with a continuous 360° azimuthal response, significantly enhancing detection efficiency by minimizing the escape of scattered photons. The smallest imaging unit utilizes an independent CsI(Tl) crystal coupled with a single SiPM, which reduces light propagation loss and improves light collection efficiency to enhance energy resolution. To simplify the electronic systems, a serial readout circuit is employed to reduce the readout channels. The experimental results demonstrate that the total energy resolution for the 137Cs source was 6.2% (FWHM) after calibrating the position and energy. Using the maximum likelihood expectation maximization algorithm for image reconstruction, the imaging system achieves accurate localization of radioactive sources with an angular resolution of 12° and clearly distinguishes the position of two radioactive sources.