Development of an HAPD with 144 channels for the aerogel RICH of the Belle upgrade

For the upgrade of the Belle detector at the KEKB collider, we are developing a proximity focusing ring imaging Cherenkov detector using aerogel as a radiator. A 144 channel HAPD (Hybrid Avalanche Photo-Detector) is one of the candidate photo-detectors. We report on the performance of a recently delivered HAPD. We also discuss results of tests of a read-out ASIC which is being developed for the readout of the HAPD. Both the HAPD and the ASIC show good performance for detection of single photons.