Development of Multi-Pixel Photon Counters

The multi-pixel photon counter (MPPC) is a newly developed photodetector with an excellent photon counting capability. It also has many attractive features such as small size, high gain, low operation voltage and power consumption, and capability of operating in magnetic fields and in room temperature. The basic performance of samples has been measured. A gain of ~10^6 is achieved with a noise rate less than 1 MHz with 1 p.e. threshold, and cross-talk probability of less than 30% at room temperature. The photon detection efficiency for green light is twice or more that of the photomultiplier tubes. It is found that the basic performance of the MPPC is satisfactory for use in real experiments.