Efficiency Comparison of Large Scintillation Counters Based on Vacuum and Silicon Photomultipliers

Abstract

The paper examines the parameters of plastic scintillation detectors with various systems for output and detection scintillation radiation, designed for detecting gamma rays over a wide energy range. Such detectors, having high light output, find broad application in nuclear physics, high-energy physics, and radiation monitoring systems. However, the detection, for instance, of low-energy gamma radiation with low light output of gamma rays requires low detection thresholds, which leads to an increase noise counts. The paper compares the efficiency of gamma detection by relatively large-sized detectors using vacuum photomultiplier tubes (PMTs) and silicon photomultipliers (SiPMs) as photodetectors. In the latter case, light is extracted from the scintillator using wavelength-shifting fibers. Detectors with such a scintillation-detection system surpass detectors with vacuum PMTs in a number of parameters. Nevertheless, the paper demonstrates that, in the low-energy gamma detection range, which is important for radiation-monitoring systems, detectors based on SiPMs and wavelength-shifting fibers, at an energy of 60 keV for example, are an order of magnitude less efficient in registration compared to detectors with vacuum PMTs. It is shown that this is due to a significant background of the SiPMs dark noise.