First Compton telescope prototype based on continuous LaBr₃-SiPM detectors

A first prototype of a Compton camera based on continuous scintillator crystals coupled to silicon photomultiplier (SiPM) arrays has been successfully developed and operated. The prototype is made of two detector planes. The first detector is made of a continuous 16 × 18 × 5mm³ LaBr ₃ crystal coupled to a 16-elements SiPM array. The elements have a size of 3 × 3 mm³ in a 4.5 × 4.05 mm² pitch. The second detector, selected by availability, consists of a continuous 16 × 18 × 5 mm³ LYSO crystal coupled to a similar SiPM array. The SPIROC1 ASIC is employed in the readout electronics. Data have been taken with a ²²Na source placed at different positions and images have been reconstructed with the simulated one-pass list-mode (SOPL) algorithm. Detector development for the construction of a second prototype with three detector planes is underway. LaBr₃ crystals of 32 × 36 mm ² size and 5/10 mm thickness have been acquired and tested with a PMT. The resolution obtained is 3.5% FWHM at 511 keV. Each crystal will be coupled to four MPPC arrays. Different options are being tested for the prototype readout.