Using a single-phase liquid argon detector with a signal yield of 4.85 photoelectrons per keV of electronic-equivalent recoil energy (keVee), we measure the scintillation time dependence of both electronic and nuclear recoils in liquid argon down to 5 keVee. We develop two methods of pulse shape discrimination to distinguish between electronic and nuclear recoils. Using one of these methods, we measure a background and statistics-limited level of electronic recoil contamination to be 7.6e-07 between 60 and 128 keVr for a nuclear recoil acceptance of 50%, with no nuclear recoil-like events above 72 keVr. Finally, we develop a maximum likelihood method of pulse shape discrimination using the measured scintillation time dependence and predict the sensitivity to WIMP-nucleon scattering in three configurations of a liquid argon dark matter detector.
Citation: Physical Review C (Nuclear Physics)
Pub Type: Journals
argon, electronic recoil, nuclear recoil, pulse shape discrimination, scintillation light, stochastic modeling, time dependence.