Development of hybrid avalanche photo detector and its readout electronics for the belle II aerogel RICH counter

Abstract

For the Belle II experiment at the superKEKB accelerator, we have been developing a proximity focusing ring imaging Cherenkov detector using a silica aerogel as a radiator (A-RICH). This counter is designed to be used at the forward end-cap region and to have pion/kaon separation with more than 4-sigma deviations at momenta up to 4 GeV/c. 144-channel Hybrid Avalanche Photo-Detector (HAPD) modules developed with Hamamatsu Photonics K.K. have been adopted as the photon detectors for the A-RICH. We started the mass production of the HAPD since 2013, and we are testing quality of the manufactured HAPDs. As for the readout of about 60,000 channels from the A-RICH, we developed an ASIC for the amplification and digitization of the signals from HAPDs. We had finished the mass production of the ASIC chips. Then we are testing all the ASIC chips before mounting them on the front-end boards attached to HAPDs. The data from several front-end boards will be merged into one board, and are sent to the Belle II central DAQ system. For this purpose, modules called "merger board" located inside the detector are under development. We are developing the firmware for the FPGA and testing it. In this report, current status of the development of HAPDs and readout electronics for the A-RICH are described.