MicroPMT–A New Photodetector for Gamma Spectrometry and Fast Timing?

Abstract

Hamamatsu recently announced the launch of a new type of a photodetector, a micro photomultiplier (microPMT or μPMT). This detector works like a classic photomultiplier but the whole device is made directly in a silicon wafer sandwiched between two glass layers. A microPMT has dimensions of only 13×10×2mm and its photocathode has size of 3×1mm. According to the producers, this newly developed photodetector keeps all the advantages of a classic photomultiplier such as high gain, high sensitivity, low noise, high speed, and low temperature dependence. The aim of the work is to verify usefulness of a microPMT in gamma spectrometry with scintillators and fast timing. In the first part of the study analysis of the energy resolution obtained with 3×3×1mm LSO, BGO and CsI(Tl) scintillators is made. The light pulse shapes of a single photoelectron and scintillation signal of LSO are also showed. The important part of the study are measurements of the number of photoelectrons and estimation of the excess noise factor. In the second part, measurements of the time jitter and timing resolution with LSO crystal for 511keV annihilation quanta are reported. All the results are compared with data obtained with classic PMTs.