Development of the new silica aerogel Cherenkov counter using WLS fiber and MPPC

In modern elementary particle experiments, π/K identification is very important. In particular, a counter which works in any magnetic field is required. Currently we are working on a new silica aerogel Cherenkov counter with a wavelength shifting (WLS) fiber and a multi-pixel photon counter (MPPC, made by Hamamatsu Photonics K.K.), which is compact and resists the magnetic field. As a preliminary experiment, we performed a beam test at the LEPS (laser-electron photon at SPring-8) beam line to examine whether the WLS fiber can collect enough Cherenkov light. Based on the result, we propose to introduce new WLS fibers which increase the light yield and to construct a detection system which can collect Cherenkov light more effectively. If this new system works properly, the detection efficiency of pions is supposed to be more than 99%.