Y. Kozakai

A novel type of proximity focusing RICH counter with multiple refractive index aerogel radiator

Abstract A proximity focusing ring imaging Cherenkov detector, with the radiator consisting of two or more aerogel layers of different refractive indices, has been tested in 1 – 4 GeV / c pion beams at KEK. Essentially, a multiple refractive index aerogel radiator allows for an increase in Cherenkov photon yield on account of the increase in overall radiator thickness, while avoiding the simultaneous degradation in single photon angular resolution associated with the increased uncertainty of the emission point. With the refractive index of consecutive layers suitably increasing in the downstream direction, one may achieve overlapping of the Cherenkov rings from a single charged particle. The impact of the observed improvement on the π / K separation at the upgraded Belle detector is discussed.

Study of RICH Counter with Silica Aerogel Radiator

A proximity focusing RICH using aerogel as the Cherenkov radiator is being developed as a new particle identification device for the Belle detector upgrade. A prototype counter was constructed with recently produced aerogel samples, arranged in a focusing configuration, and a test beam experiment was carried out in order to evaluate the performance of the apparatus. With this device we have achieved a pi-K separation that exceeded 5sigma at 4 GeV/c, with ap9 detected photoelectrons per track. We have also studied the influence of various parameters like radiator refractive index combinations on the performance of the apparatus.