Tests of a proximity focusing RICH with aerogel as radiator

I. Adachi 2, I. Bizjak 3, A. Gorisek 3, T. Iijima 2, M. Iwamoto 1, S. Korpar 3,6, P. Krizan 5,3, R. Pestotnik 3, M. Staric 3, A. Stanovnik 3,4, T. Sumiyoshi 2, K. Suzuki 2 and T. Tabata 1

1 Chiba University, Chiba, Japan
2 High Energy Accelerator Research Organization (KEK), Japan
3 Jozef Stefan Institute, Ljubljana, Slovenia
4 Faculty of Electrical Engineering, University of Ljubljana, Slovenia
5 Faculty of Mathematics and Physics, University of Ljubljana, Slovenia
6 Faculty of Chemistry and Chemical Engineering, University of Maribor, Slovenia


    A study was carried out to measure the performance of a proximity focusing RICH with aerogel as radiator and multianode PMTs as the detector of Cherenkov photons. The yield and resolution were measured by using a pion test beam. The parameters of the counter were determined for various aerogel materials, densities, thicknesses, angles of incidence, as well as a function of the incoming beam momentum. A light collection system using a single lens per PMT tube was tested as well as a method to increase the active area. Finally, the results were used to study the feasibility of such a counter for the upgrade of the Belle sepctrometer for the high luminosity operation.