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

Abstract

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 4,272 keV enabled us to achieve very low background condition, however, at the same it causes difficulties in calibrating the detector's Q-value region because of the absence of a standard high-energy ${\hat{I}}^3$-ray source. Therefore, we have developed a novel calibration system based on ${\hat{I}}^3$-ray emission by neutron capture on ${}^{28}$Si, ${}^{56}$Fe and ${}^{58}$Ni nuclei. In the paper, we report the development of the new calibration system as well as the results of energy calibration in CANDLES up to 9 MeV.

6 pages, 7 figures