Characterization of LaBr3:Ce and CeBr3 calorimeter modules for 3D imaging in gamma-ray astronomy

For the purpose of future space instrumentation for γ-ray astronomy, we developed a small prototype of a Compton telescope and studied novel detector modules aimed for Compton imaging. We assembled and tested 2 modules, one with a cerium-doped lanthanum(III) bromide (LaBr3:Ce) crystal and the other with cerium(III) bromide (CeBr3). Both crystals measure 5×5 cm2 in area and are 1 cm thick. They are coupled to and read out by 64-channel multi-anode PMTs. Our goals are to obtain the best possible energy resolution and position resolution in 3D on the first impact of an incident γ-ray within the detector. Both information are vital for successful reconstruction of a Compton image with the telescope prototype. We developed a test bench to experimentally study both modules and have utilized a customized readout electronics and data acquisition system. Furthermore, we have written a detailed Geant4 simulation of the experiment, and utilize simulated data to train an Artificial Neural Network (ANN) algorithm to create a simplified 3D impact position reconstruction method. We give experimental test results obtained by both modules and present detailed parametrization and results from the Geant4 simulation and from the ANN. We compare and discuss the performance of the modules and conclude by giving a brief overview of the future prospects for using such modules in γ-ray astronomy.