F.C.T. Barbato

Study of semi-transparent conductive layers for the realization of high quantum efficiency transmission mode CsI photocathodes for vacuum photodetectors

We worked on the R&D of an innovative photodetector, the Vacuum Silicon Photomultiplier Tube (VSiPMT). The VSiPMT is composed by a photocathode and a solid state amplification stage. A semi-transparent conductive layer is necessary to supply voltage and to obtain a highly efficient CsI photocathode. Since the literature is poor on this topic we performed a systematic and detailed study of a set of semi-transparent conductive layers, made by different material and thickness. A CsI photocathode was evaporated on each sample. The impact of the semi-transparent conductive layer on the quantum efficiency of the photocathode is discussed.

Hamamatsu C11204-01 calibration, test and design of a dedicated LabVIEW interface

In the last 50 years solid state devices have been widely used as radiation detectors (photons, betas, fast electrons and heavy ions) thanks to the advantages they offer with respect to photomultiplier tubes technology. However, despite their benefits (low power consumption, small size, low costs), semiconductors are very sensitive to temperature variations. This means that for those experiments using solid state detectors without any thermal control, the correct operation of the detectors is affected by the environmental condition. To solve this problem Hamamatsu Photonics realized the C11204-01 device: a special voltage supply module for silicon photomultipliers which compensates the overvoltage at different temperatures. In the following work we present the results of the calibration of this device and a test we performed on a silicon photomultiplier, by means of a LabVIEWTM interface designed ad hoc for this purpose.

VSiPMT: An hybrid approach to high resolution photodetectors

The VSiPMT (Vacuum Silicon Photomultiplier Tube) is an innovative design for a revolutionary hybrid photodetector. The idea consists in replacing the classic dynode chain of a classic PMT with a SiPM. This new device aims at extending SiPM technology to large detection volumes. In this configuration, we match the large sensitive area of a photocathode with the performance of SiPM technology, which thererefore acts like an electron detector and current amplifier. The excellent photon counting capability, fast response, low power consumption and great stability are among the most attractive features of the VSiPMT. Hamamatsu realized two VSiPMT industrial prototypes with a photocathode of 3 mm diameter. In this work we present the progresses on the realization of a 1-inch prototype based on CsI photocathode and the preliminary tests we are performing on it.