Development of the compact aerogel Cherenkov counter with MPPC

We have been investigating hadron production experiments using a tagged photon beam (Eγ<1.3GeV) at the Tohoku University ELPH. We have recorded the data including the e+e- background events to avoid a bias in the acceptance. It is necessary for efficient data taking to remove the e+e- events in the trigger level with high rate beam.

The maximum momentum of e+/e- is 1.3GeV/c and we are developing an compact Aerogel Cherenkov counter (ACC) using a refractive index of 1.01 to separate e/π in the momentum range. The size of the aerogel is about 3 x 6 x 4[cm^3]. Since the ACC is placed in the magnetic field, we have plan to use a fine mesh dynode type PMT or MPPC (SiPM) to detect the Cherenkov light. In general, the photon detection efficiency of MPPC is higher than PMT, but it depends on the way of installation.

We will report test results about reflector, and photon sensors. Additionally, we will show a bias voltage dependence of gain about MPPC for production version.