Research & development on advanced detectors for B-factories.

国家高能物理实验室（KEK）正在建造一个不对称的B工厂。峰值亮度的目标是10^<34>cm^<-2>sec。<-1.>贝儿合作建立了一个探测器来研究B介子衰变中的CP破坏。基于当前设计的贝儿探测器的Monte Carlo研究表明，通过测量CKM三角形的三个角和三条边，可以确定标准模型中CP破坏的测试。为了实现这一目标，一个很好的测量的B衰变顶点和一个优秀的pi/K识别高达4 GeV/c是必要的。我们计划建立一个硅微顶点探测器（SVD）的双面硅条探测器（DSSD）与双金属层（DML）的z带读出。在本项目中，我们在KEK/B工厂研究了SVD的优化设计，并成功地进行了大型DSSD的DML，SVD读出电子学，包括新的128通道低噪声模拟存储器VLSI的，一种新的无线键合方法的DSSD的R&amp;D研究。作为贝儿实验的pi/K识别器件的候选人，在本项目中，我们设想了一个快速环形映像切伦科夫（RICH）计数器，并对其进行了深入的研究与开发，利用LiF辐射器和TEA/CH_4混合气体，我们获得了一个全尺寸的快速RICH计数器原型，其3 σ pi/K分离高达2.86 GeV/c。然后，我们测试了两个原型丰富的计数器与不同的碘化铯光电阴极。这两个探测器都成功地在光束中观测到了预期的切伦科夫环。然而，CsI光电阴极的量子效率被发现在两种情况下仅为约10%，而我们需要的值大于15%。

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%.