The Vacuum Silicon PhotoMultiplier Tube (VSiPMT) is a new concept of photodetector based on the combination of the outstanding performances of SiPMs and the large sensitive surfaces of PMTs. Such device is made of a PMT standard envelope, with a photocathode for photon-electron conversion and an electrostatic focusing system that accelerates and focuses the generated photoelectrons towards a small focal area covered by a SiPM. The electron multiplication stage is the heart of the device and represents the real innovation with respect to the standard PMT technology. Therefore, a huge preliminary work aimed at the study of the performances of SiPMs as electron multipliers has been mandatory in order to investigate the feasibility of the VSiPMT. The extremely positive results achieved in this phase encouraged Hamamatsu Photonics to realize some prototypes of VSiPMT, that have been extensively characterized in the laboratories of INFN – Section of Naples. In this presentation some highlights about the main milestones of the project will be provided. In particular, taking as a starting point the results of the prototype characterization, the so-called “phase 2” aimed at the realization of a new optimized generation of VSiPMT prototypes will be discussed.

INFN - Section of Naples

Università degli Studi di Napoli Federico II