A new SiPM-based positron annihilation lifetime spectrometer using LYSO and LFS-3 scintillators

Positron annihilation lifetime (PAL) spectroscopy is a unique technique to characterize atomic-scaled microstructure of materials, especially the vacancy-type defects. Compared to photomultiplier tube, silicon photomultiplier (SiPM) has a higher quantum efficiency, a more compact size, and a much lower price. Considering the evident advantages of SiPM, we developed a SiPM-based PAL (SiPM-PAL) spectrometer by using LFS-3 and LYSO scintillators in the sizes of 3×3×l mm3. The performance of the SiPM-PAL spectrometer was studied with four different scintillator lengths (l) of 5.0, 9.5, 13.8, and 20.0 mm. Under the same experimental conditions, with LFS-3 scintillator length decreasing from 20.0 to 5.0 mm, the time resolution (in FWHM) of SiPM-PAL spectrometer was significantly improved from 174.9 to 135.9 ps. While for the SiPM-PAL spectrometer with LYSO scintillators, the time resolution improved from 181.9 to 137.0 ps with scintillator length decreasing from 20.0 to 5.0 mm. Compared to conventional PAL spectrometer using photomultiplier tubes, a novel, small size, and low cost PAL spectrometer is successfully constructed by using SiPMs. Easy customization and superiority in time resolution and small size of SiPM-based scintillation detectors guarantee high flexibility and adaptability to the SiPM-PAL spectrometers, positron micro-beam facilities, and angular correlation of positron annihilation radiation measurements.