Multichannel SiPM test readout system for gamma-ray measurements with monolithic inorganic CeBr_{3}

Energy resolution and the detection efficiency for gamma quanta are fundamental properties in the construction of detectors for ionizing radiation. In this study, a SiPM-based photodetector coupled to a monolithic inorganic CeBr_{3} crystal is exposed to gamma rays in order to study the performance of the CeBr_{3} crystal. Measurements are made using three different radioactive sources - ^{137}Cs, ^{22}Na, and ^{60}Co. For each source, the measurements are conducted at several SiPM bias voltages. Furthermore, two CeBr_{3} crystals with different thicknesses are used in order to study how detector efficiency is affected by crystal dimensions. A preliminary analysis of the data is presented.

💡 Research Summary

This research presents a detailed investigation into the performance characteristics of a gamma-ray detection system utilizing a Silicon Photomultiplier (SiPM) coupled with a monolithic inorganic $CeBr_3$ (Cerium Bromide) crystal. The primary objective of the study is to evaluate two critical parameters in radiation detection: energy resolution and detection efficiency, which are essential for the development of high-precision spectroscopic instruments.

The experimental methodology is structured around a multi-variable analysis to determine the optimal operating conditions for the detector. To ensure a comprehensive energy range coverage, the researchers employed three distinct radioactive isotopes: $^{137}Cs$, $^{22}Na$, and $^{60}Co$. By using these sources, the study assesses the detector’s response across different gamma-ray energy spectra. A key technical aspect of the experiment involves varying the SiPM bias voltage. Since the gain and Photon Detection Efficiency (PDE) of SiPMs are highly sensitive to the overvoltage, analyzing the relationship between bias voltage and energy resolution is crucial for minimizing electronic noise and maximizing the signal-to-noise ratio (SNR).

Furthermore, the study addresses the physical dimensions of the detector by comparing two $CeBr_3$ crystals of different thicknesses. In gamma-ray spectroscopy, the thickness of the scintillator directly influences the probability of photon interaction via the photoelectric effect and Compton scattering. While increasing the crystal thickness enhances the detection efficiency by providing a larger interaction volume, it may simultaneously affect the energy resolution due to light attenuation and scattering within the monolithic structure. By investigating this thickness-dependent performance, the research provides vital insights into the trade-offs between detection sensitivity and spectral precision.

The preliminary results presented in this paper lay the groundwork for optimizing SiPM-based scintillator systems. The integration of SiPM technology offers significant advantages over traditional Photomultiplier Tubes (PMTs), including reduced power consumption, compact form factor, and enhanced stability in magnetic fields. This study serves as a fundamental step toward the realization of next-generation, highly efficient, and portable gamma-ray spectrometers suitable for diverse applications in medical imaging, nuclear security, and environmental monitoring.