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 7.6×10−7 between 60 and 128 keV of nuclear recoil energy (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.
@article{arxiv.0801.1531,
title = {Scintillation time dependence and pulse shape discrimination in liquid argon},
author = {W. H. Lippincott and K. J. Coakley and D. Gastler and A. Hime and E. Kearns and D. N. McKinsey and J. A. Nikkel and L. C. Stonehill},
journal= {arXiv preprint arXiv:0801.1531},
year = {2014}
}