First measurement of surface nuclear recoil background for argon dark matter searches
Abstract
One major background in direct searches for weakly interacting massive particles (WIMPs) comes from the deposition of radon progeny on detector surfaces. The most dangerous surface background is the Pb recoils produced by Po decays. In this letter, we report the first characterization of this background in liquid argon. The scintillation signal of low energy Pb recoils is measured to be highly quenched in argon, and we estimate that the 103keV Pb recoil background will produce a signal equal to that of a ~5keV (30keV) electron recoil (Ar recoil). In addition, we demonstrate that this dangerous Po surface background can be suppressed by a factor of ~100 or higher using pulse shape discrimination methods, which can make argon dark matter detectors near background-free and enhance their potential for discovery of medium- and high-mass WIMPs. We also discuss the impact on other low background experiments.
Keywords
Cite
@article{arxiv.1609.07089,
title = {First measurement of surface nuclear recoil background for argon dark matter searches},
author = {Jingke Xu and Chris Stanford and Shawn Westerdale and Frank Calaprice and Alexander Wright and Zhiming Shi},
journal= {arXiv preprint arXiv:1609.07089},
year = {2017}
}
Comments
4 pages, 3 figures