Measurement of light yield dependence on electron energy for SNO+ scintillator

SNO+ is a multi-purpose neutrino experiment whose reach extends to the following areas of neutrino physics: neutrinoless double beta decay (with Nd-loaded scintillator), geo-neutrinos, reactor and low-energy solar neutrinos, as well as supernova neutrinos. It is a $\sim$780-tonne liquid scintillator detector currently under construction at the SNOLAB facility in Sudbury, Ontario,Canada. The scintillator to be used in SNO+ is linear alkylbenzene (LAB) with $\sim$2 g/L of PPO (2,5-diphenyloxazole). In this talk, we describe an experiment to test the linearity of the response of LAB-PPO with respect to electrons. We find that below $\sim$0.4 MeV, the energy scale of LAB-PPO becomes non-linear. An explanation is given in terms of Cherenkov light absorption and re-emission by the scintillator.