Upgrade for the Hyperion Detector Platform: Analog SiPM and TOFPET ASIC Integration

The Hyperion PET detector platform comprises sensor tiles, which are connected through flexible cables to the mainboards of the PET detector modules. The versatility of analog SiPM / ASIC combinations will be used to design sensor tiles for multiple PET/MRI projects. SiPMs and digitizing ASICs are integrated into the detector platform. The first implementation will have a form factor of $49 \times 49 \mathrm{~mm}^{2}$ and use 4-mm SiPMs. The resulting 144 SiPMs shall be read out by a single TOFPET ASIC with 64 input channels to improve the required space, power consumption and costs. Several channel compression schemes with a factor of at least 2.25 are under investigation: Row-column-sum and matrix-head circuits with active components such as amplifiers as well as different passive connection schemes using the light-spread of a crystal over multiple sensors. Simple patterns allow straightforward algorithms for crystal identification, whereas other more optimized patterns employ more advanced processing algorithms, like neural networks, for this task. Simulations show that the probability to find the correct crystal is only reduced by $1.6 \%$ to $4.6 \%$ compared to the uncompressed data from all 144 channels. Test PCBs were designed for SiPMs and for the compression schemes as interposing PCBs. At the same time, a sensor tile is being designed with a TOFPET2 ASIC and an FPGA on the electronics side and just two connectors for the SIPMs on the other side. As such, the digitizing ASIC, the compression schemes, and the SiPMs can be freely combined.