Test of the Hamamatsu MPPC module S11834 as a RICH photon detector

In our previous studies, we have shown that silicon photo-multipliers can be used as single photon detectors in a RICH counter (Korpar et al., 2009, 2010 [1,2]). Their main advantage with respect to the classical photo-multiplier tubes is the operation in high magnetic fields, while their disadvantage is a relatively high dark count rate. Recently, Hamamatsu made commercially available sensors with a rather low dark count rate (≈0.1 MHz/mm2) and with a larger active area, offering a possibility for a much better signal-to-noise ratio. We have designed, constructed and tested a module with Hamamatsu 8×8 channel S11834 MPPCs. To increase the geometric acceptance, light concentrators have been employed. In the present contribution we discuss the results of studies of the light concentrator design optimization and of the detector module response to fast light pulses. Also presented are the results of RICH prototype tests in a test beam.