Development of RICH counters towards the KEKB/Belle upgrade

We are developing two types of novel ring imaging Cherenkov (RICH) counters for the upgrade of the Belle detector at the KEKB collider; the “Time-Of-Propagation (TOP) counter” for the barrel part, and the “proximity focusing aerogel RICH” for the forward endcap. Both detectors are based on advanced radiator and photodetection technologies, and aims at providing > 4 σ K / π separation at 4 GeV/c. This paper presents a brief summary of the R&D status for these two detectors.