Dual Ring Prototype Electronic System for the Small Animal Fast Insert for MRI

SAFIR is a high-rate PET insert for a preclinical 7 T MRI scanner, aiming at studying fast biological processes in small animals, using tracer activities up to 500 MBq. The full detector comprises 15360 channels, each composed of a LYSOcrystal and a $S$ iPM photo-sensor. A dedicated readout system, operating inside the MRI magnet of 200 mm inner diameter acquires 40 kHz of hits per channel. PETA6 ASICs digitize amplitude and time of the hits. FPGAs read, processand transfer, via optical links, the digital data. We present the readout system in detail, together with first test results.