Development of a new 2-inch hybrid photo-detector using MPPC

We have newly developed a Hybrid Photo-Detector (HPD) with 2-inch diameter. It consists of a bialkali photocathode and a 3 mm x 3 mm Multi-Pixel-Photon Counter (MPPC) sealed in a glass tube. The electric field inside the tube is designed so that photoelectrons emitted from the photocathode are collected in the MPPC, where photoelectrons are amplified. For conventional HPDs with an avalanche diode, extremely high voltage such as -8kV has to be provided to achieve gain sufficient for single photon detection. However, our HPD with MPPC has single photon sensitivity only with lower voltage like PMTs due to high gain of MPPC. In addition, this device can cover larger area with only one MPPC. These features enable us to easily handle high performance HPD in various applications, such as high energy physics, biomedical field etc. This test sample was produced in 2016, and we have checked its basic characteristics. The peak photocathode quantum efficiency was found to be very high of 37% at the wavelength of 340 nm. We have confirmed that HPD with MPPC has capability of single photon detection in low operation voltage less than -2 kV. This report will present detailed performance studies of this sample