The energy calibration system for CANDLES using (n,γ) reaction

摘要

Calcium fluoride for the study of Neutrinos and Dark matters by Low-energy Spectrometer (CANDLES) searches for neutrino-less double-beta decay of ~(48)Ca using a CaF_2 scintillator array. A high Q-value of ~(48)Ca at 4268 keV enabled us to achieve low background, however, at the same time it causes difficulties in calibrating the detector's Q-value region because of the absence of a standard high-energy γ-ray source. Therefore, we have developed a novel calibration system based on y-ray emission by neutron capture on ~(28)Si, ~(56)Fe, and ~(58)Ni nuclei. In this paper, we report the development of the new calibration system as well as the results of energy calibration in CANDLES up to 9 MeV.