A multichannel compact readout system for single photon detection: design and performances Frontier Detectors for Frontier Physics presented by Paolo Musico I.N.F.N. Genova – via Dodecaneso, 33 – 16146 – GENOVA (Italy) A compact independent channel readout system for an array of MAPMTs has been developed and tested. The front-end is based on a VLSI custom chip called MAROC, developed by IN2P3 Orsay (F). Extensive using of FPGA gives a very good flexibility. Up to 4096 channels can be acquired using a Personal Computer connected with an high speed USB 2.0 link. A complete system has been built and tested. Eight 256 anodes Hamamatsu H-9500 have been arranged on a boundary of a 3  3 matrix for a grand total of 2048 channels. This system has been used to collect Cherenkov light coming from an aerogel radiator (COMANCHE project). The system has proved to be effective in single photon identification. PRELIMINARY

The system can be run self triggered or using an external strobe. The front end generates 64 fast digital HITs: their logical OR can trigger the acquisition of the analog data. This is the 1st level trigger. The HITs information are transferred to the central unit on which a more sophisticated algorithm can be run (2nd level). A topological finding algorithm is implemented to identify 2  2 spots on 8  8 or 16  16 matrixes. The pattern finding process is very fast: the 2nd level trigger can be computed in about 2 ÷ 2.5 μs. Additional improvements will include more sophisticated 1st level and boundary effects between different sensors at 2nd level. SPECT detectors are in advanced realization phase: efficient triggering is mandatory. Studies are in progress to use this system also for PET computing the coincidence trigger externally in less than 100 ns. The architecture of the system is consistent with the Silicon Photomultipliers: only the front end needs to be optimized.