High Gain Hybrid Photomultipliers Based on Solid State p-n Junctions in Geiger Mode and Their use in Astroparticle Physics

In astroparticle physics photomultiplier tubes play a crucial role in the detection of fundamental physical processes. After about one century of standard technology (photocathode and dynode electron multiplication chain), the recent strong development of modern silicon devices has brought to maturity a new generation of photodetectors based on an innovative, high-quality, cost effective technology. In particular the most promising development in this field is represented by the rapidly emerging CMOS p-n Geigermode avalanche photodiode technology (G-APD or SiPM), for high-speed single photon detection with high gain and linearity. Most applications will require collection of light from even larger surfaces or volumes, so it is necessary to increase the active surface and the angular acceptance of SiPMs while keeping high sensitivity. The main purpose of this research is, therefore, to provide an attractive solution to overcome this problem. The idea is to realize a hybrid detector (Vacuum Silicon PhotoMulTiplier,VSiPMT), where the dynodes structure of a classical Vacuum PhotoMultiplier Tube (VPMT) is replaced by an array of G-APDs, which collects the photoelectrons emitted by photocathode and acts as an electron multiplier.