Pulse-shape discrimination between electron and nuclear recoils in a NaI(Tl) crystal

Abstract

We report on the response of a high light-output NaI(Tl) crystal to nuclear recoils induced by neutrons from an Am-Be source and compare the results with the response to electron recoils produced by Compton-scattered 662 keV gamma-rays from a Cs-137 source. The measured pulse-shape discrimination (PSI)) power of the NaI(Tl) crystal is found to be significantly improved because of the high light output of the NaI(Tl) detector. We quantify the PSI) power with a quality factor and estimate the sensitivity to the interaction rate for weakly interacting massive particles (WIIMPs) with nucleons, and the result is compared with the annual modulation amplitude observed by the DAMA/LIBRA experiment. The sensitivity to spin-independent WIMP-nucleon interactions based on 100 kg.year of data from NaI detectors is estimated with simulated experiments, using the standard halo model.