Discrimination between electron and nuclear recoil events in a liquid argon scintillation detector has been demonstrated with simulations by using the differences in the scintillation photon time distribution between these classes of events. A discrimination power greater than 10^{8} is predicted for a liquid argon experiment with a 10 keV threshold, which would mitigate electron and gamma-ray backgrounds, including beta decays of 39-Ar and 42-Ar in atmospheric argon. A dark matter search using a ~2 kg argon target viewed by immersed photomultiplier tubes would allow a sensitivity to a spin-independent WIMP-nucleon cross-section of ~10^{-43} cm^{2} for a 100 GeV WIMP, assuming a one-year exposure. This technique could be used to scale the target mass to the tonne scale, allowing a sensitivity of ~10^{-46} cm^{2}.
@article{arxiv.astro-ph/0411358,
title = {Direct WIMP Detection Using Scintillation Time Discrimination in Liquid Argon},
author = {M. G. Boulay and A. Hime},
journal= {arXiv preprint arXiv:astro-ph/0411358},
year = {2007}
}