Research & development on advanced detectors for B-factories.

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National Laboratory for High Energy Physics, KEK,is building an asymmetricB-factory. The goal of the peak luminosity is 10^<34> cm^<-2> sec^<-1.> The BELLE collaboration builds a detector to study of CP violation in B meson decays. It is shown by Monte Carlo studies based on the current design of the BELLE detector that a definitive test of CP violation in the standard model may be possible by measuring the three angles and the three sides of the CKM triangles. To realize this goal, a good measurement of the B decay vertices and a excellent pi/K identification up to 4 GeV/c are necessary. We plan to build a Silicon micro Vertex Detector (SVD) made of Double-sided Silicon Strip Detectors (DSSD) with a Double-Metal Layr (DML) for the z-strip readout. In this project, we studied the optimized design of SVD at the KEK/B-factory and successfully performed R&D studies on large DSSD with DML,SVD readout electronics including new 128 channel low noise preamplifier VLSI's with analog memory, a new wireless bonding method for DSSD.As a candidate of the pi/K identification device of the BELLE experiment, in this project we assumed a fast Ring Image Cherenkov (RICH) counter and performed a intensive R&D on it. We obtained the 3sigmapi/K separation up to 2.86 GeV/c for a full size prototype of the fast RICH counter using the LiF radiator and a TEA/CH_4 gas mixture. We then tested two prototype RICH counters with different CsI photocathodes. Both detectors were operated successfully in beams observing expected Cherenkov rings. However the quantum efficiency of the CsI photocathode was found to be only about 10% in both cases while we need the value larger than 15%.