Investigation of Silicon Photomultiplier detectors for development of space borne high energy radiation experiments

Abstract

Silicon photomultiplier (SiPM) is a low light photodetector which is new in the field of photo-detection and has the capability of detecting a single photon. SiPM when coupled with Scintillator can work as high energy radiation detector which find applications in many diverse fields like high energy physics, medical imaging, planetary exploration etc. Scintillation detectors absorb the radiations and generate output photons in the visible energy range. These light photons when detected by the SiPM detector, generate electrical signal in the output, proportional to the number of photons. Scintillator + SiPM detectors are getting popular in many ground based applications, but their usage in the space experiments have not been fully explored. newlineIn this thesis work, selected models of the SiPMs have been characterized for a wide temperature range keeping in mind their usage in the future space experiments. Methods for deriving some of the important parameters of the SiPM like breakdown voltage, SiPM s gain, quenching resistor, and microcell recovery time are documented. The temperature dependence of each of these parameters has been calculated and reported. Device to device variations are seen by using multiple numbers of SiPMs from same manufacturing lot. The plotting of the current with SiPM over-voltage (and#61508;V) for all different SiPMs shows that reverse bias current after breakdown voltage becomes proportional to and#61508;V2. In the experiment, SiPM s gain is found to be temperature dependent having negative temperature coefficient. In order to have fixed gain in the radiation spectroscopy and to reduce the FWHM (Full width at Half Maximum) broadening, SiPM should be 1) operated at a controlled temperature or else 2) biasing voltage of SiPM needs to be variable as per the ambient temperature. The second method requires prior measurements of the SiPM s breakdown voltages at different operating temperatures. newlineSiPMs are currently available only for the commercial usage. The intended use of SiPMs is for the future space appli