A numerical study attitude of compatibility in scintillator detectors through matching pair scintillator-photodiode materials

Abstract

In a group of scintillator detectors where photodiodes have replaced photomultiplier tubes, one way to increase the efficiency of the device is proper matching between the radiation spectrum of the scintillator and the spectral sensitivity of the photodiode. This study seeks to find the most compatible pair of scintillators with photodiodes using the simulation of photodiodes in COMSOL Multiphysics. In this research, three scintillators NaI(Tl), CsI(Tl), and Bi4Ge3O12 (BGO), along with three photodiodes silicon (Si) and gallium arsenide (GaAs) and indium phosphide (InP), have been studied to find the best compatible pair. Among the selected scintillators and photodiodes, the pair of Si with BGO produced the highest output current. Generating more current in a detector for constant input radiation means more sensitivity of that detector to the incident beam. In another part of this research, using the simulated photodiode in COMSOL Multiphysics, the current generated in the photodiode has been obtained for a fixed value of the ratio of the length of the photodiode to the junction depth of doping for various lengths. Then, using the Origin Pro software, the best curve corresponding to the data obtained from the simulation was determined. The results showed that these points coincide with an exponential curve with an excellent approximation. Using these types of detectors in the International Linear Collider (ILC) and in the Positron Emission Tomography (PET) field shows the unique applications of detectors.