Razmik Mirzoyan (Max-Planck-Institute for Physics, Munich, Germany)
Strong Boost of PMT and SiPM Parameters for Astro-Particle Physics Experiments

Most experiments in Astro-Particle Physics are based on using some type of light detector. The Astro-particle physics group in Max-Planck-Institute for Physics (MPIP) has long traditions in light detector developments, several novel sensors were initiated by us. We have developed very high Quantum Efficiency (QE) Hybrid Photo Detectors (HPD) with GaAsP photocathode and Avalanche Photo Diodes (APD) matrixes in cooperation with industrial partners in the past. Also, in recent years we co-developed and strongly improved classical Photo Multiplier Tubes (PMT). Since mid 1960fs the QE of classical PMTs was stagnating on the level of ~25 % and the photo electron (ph.e.) Collection Efficiency (CE) was on the level of ~80 %. In recent ~8 years we initiated up to 85 % improvement of the Photon Detection Efficiency (PDE = QE x ph.e. CE) of bialkali type PMTs. The MAGIC project was the first to profit from these developments, the new PMTs allowed us operating the telescopes above a low energy threshold of 50 GeV. The most recent PMTs can provide an average peak QE of ~40 % and a ph.e. collection efficiency of 95-98 %. These can ensure a very low threshold for the telescopes of the Cherenkov Telescope Array (CTA), down to energies 20-30 GeV. Along with vacuum tube technology in recent ~12 years we are closely cooperating with researchers, who were pioneering the emergence and developments of SiPM. Our cooperation, also with industrial partners, showed fruitful results, top-class sensors became available, setting new standards in PDE and cross-talk. In my presentation I would like to go over the basics of light detection as well as over the development of different type sensors, focusing on super-bialkali PMTs and on SiPMs.