Light Channel Signal Analysis with the Lithium Molybdate Crystal R&D Detectors for AMoRE-II Experiments

This paper presents a comparative study of various light detectors (LDs) developed for different phases of the AMoRE neutrinoless double beta decay experiment. We analyze the performance of these detectors in terms of characteristics such as time response, light collection, and energy resolution. Our primary focus is on evaluating the performance of the AMoRE-II light detector, which is integral to the forthcoming AMoRE-II experiment. It is found that AMoRE-II type LDs outperform other previous light detector types. The best-performing LD exhibits FWHM energy resolution of 99, 198, 198, and 481 eV for baseline and ⁵⁵Fe X-ray energies of 5.9, 6.5, and 17.5 keV molybdenum X-ray, respectively. We adopted a convolution method to estimate the energy of the scintillation signals from 2.615 MeV gamma rays fully absorbed in a lithium molybdate crystal. The measured energy of scintillation light with AMoRE-II type LDs falls in the range of 2.1–2.5 keV, which corresponds to 0.80–0.96 keV/MeV. This measured energy is approximately 14–39\(\%\) higher than that measured with previous LD types for the experiments.