The measurement of liquid scintillator nonlinear response and intrinsic energy resolution

Abstract

Abstract For Jiangmen Underground Neutrino Observatory the requirements < 1 % energy scale uncertainty and 3 % at 1 MeV energy resolution are crucial in order to determine neutrino mass hierarchy. In this study, we focus on non-linearity due to ionization quenching and intrinsic energy resolution of the liquid scintillator. To measure them a small-scale laboratory setup was developed and the measurement of Birk’s quenching constant kB = 0.0196 ± 0.0019 (stat) ± 0.0030 (syst) cm/MeV was provided. With the assumption of negligible light collection term, intrinsic energy resolution term was determined: vint (50keV) ≈ 0.02 ± 0.005. This value is comparable with the statistical term of JUNO, therefore the effect could significantly contribute into the total energy resolution at this energy. Further studies should be directed toward accurate estimation of light collection effects.