Abstract and subjects
High-efficiency solid-state photodetectors such as silicon avalanche photodiodes (SiAPDs) are often used in applications limited by size, weight, and power consumption (SWaP). However, high-SWaP photomultiplier tubes (PMTs) are generally preferred to low-SWaP SiAPDs for use in scintillator applications due to a mismatch between the intrinsic scintillator emission wavelengths and the spectral response of the SiAPD. To resolve this discrepancy, we have developed a method of applying wavelength-shifting (WLS) coatings to scintillator crystals to shift peak emission into a more sensitive wavelength region of the SiAPD. The higher quantum efficiency offered by the SiAPD in this region is accessed by the shifted scintillator emission, resulting in increased light collection and improved energy resolution.Expanding on previous WLS research conducted on nonhygroscopic crystals, this research focuses on sodium-doped CsI (CsI:Na) and cerium-doped Cs2LiYCl6 (CLYC:Ce) crystals to demonstrate the application of WLS methods to hygroscopic scintillators. Optical characterization techniques such as radioluminescence (RL) spectroscopy and quantum yield (QY) measurements determine the efficacy of the WLS mechanism, while gamma-ray spectroscopy measurements quantify the increase in light collection and offer a comparative view on energy resolution improvement achieved by coupling a coated crystal to an SiAPD over an uncoated crystal to a PMT.The following conference record contains a brief summary of research presented at IEEE NSS MIC 2017. Publications containing a more comprehensive account of this work will be submitted for peer-review.