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 ${}^{206}$Pb recoils produced by ${}^{210}$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 ${}^{206}$Pb recoil background will produce a signal equal to that of a ~5keV (30keV) electron recoil (${}^{40}$Ar recoil). In addition, we demonstrate that this dangerous ${}^{210}$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.

4 pages, 3 figures

References in corpus (15)

• Results from a search for dark matter in the complete LUX exposure
• Dark Matter Results from 225 Live Days of XENON100 Data
• Dark Matter Results from First 98.7-day Data of PandaX-II Experiment
• Physics reach of the XENON1T dark matter experiment
• Improved Limits on Scattering of Weakly Interacting Massive Particles from Reanalysis of 2013 LUX data
• First Results from the DarkSide-50 Dark Matter Experiment at Laboratori Nazionali del Gran Sasso
• Search for Neutrinoless Double-Beta Decay of ${}^{130}$Te with CUORE-0
• Results from the first use of low radioactivity argon in a dark matter search
• Performance of scintillation materials at cryogenic temperatures
• Results on low mass WIMPs using an upgraded CRESST-II detector
• XENON100 Dark Matter Results from a Combination of 477 Live Days
• Measurement of Scintillation and Ionization Yield and Scintillation Pulse Shape from Nuclear Recoils in Liquid Argon
• Improved WIMP-search reach of the CDMS II germanium data
• Atomic limits in the search for galactic dark matter
• Temperature dependence of alpha-induced scintillation in the 1,1,4,4-tetraphenyl-1,3-butadiene wavelength shifter

Cited by in corpus (4)

• DarkSide-50 532-day Dark Matter Search with Low-Radioactivity Argon
• Wavelength shifters for applications in liquid argon detectors
• Surface background suppression in liquid argon dark matter detectors using a newly discovered time component of tetraphenyl-butadiene scintillation
• Technique for Surface Background Rejection in Liquid Argon Dark Matter Detectors using Layered Wavelength-Shifting and Scintillating Thin Films