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Title: First measurement of surface nuclear recoil background for argon dark matter searches

Abstract

Here, one major background in direct searches for weakly interacting massive particles (WIMPs) comes from the deposition of radon progeny on detector surfaces. A dangerous surface background is the 206Pb nuclear recoils produced by 210Po decays. In this paper, 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 103 keV 206Pb recoil background will produce a signal equal to that of a ~5 keV (30 keV) electron recoil ( 40Ar recoil). In addition, we demonstrate that this dangerous 210Po surface background can be suppressed, using pulse shape discrimination methods, by a factor of ~100 or higher, which can make argon dark matter detectors near background-free and enhance their potential for discovery of medium- and high-mass WIMPs. Lastly, we also discuss the impact on other low background experiments.

Authors:
 [1];  [1];  [1];  [1];  [2];  [1]
  1. Princeton Univ., NJ (United States). Department of Physics
  2. Queen's Univ., Kingston, ON (Canada). Department of Physics, Engineering Physics, and Astronomy
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1426118
Alternate Identifier(s):
OSTI ID: 1392729
Report Number(s):
LLNL-JRNL-703423
Journal ID: ISSN 2470-0010; PRVDAQ
Grant/Contract Number:
AC52-07NA27344
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physical Review D
Additional Journal Information:
Journal Volume: 96; Journal Issue: 6; Journal ID: ISSN 2470-0010
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS

Citation Formats

Xu, Jingke, Stanford, Chris, Westerdale, Shawn, Calaprice, Frank, Wright, Alexander, and Shi, Zhiming. First measurement of surface nuclear recoil background for argon dark matter searches. United States: N. p., 2017. Web. doi:10.1103/PhysRevD.96.061101.
Xu, Jingke, Stanford, Chris, Westerdale, Shawn, Calaprice, Frank, Wright, Alexander, & Shi, Zhiming. First measurement of surface nuclear recoil background for argon dark matter searches. United States. doi:10.1103/PhysRevD.96.061101.
Xu, Jingke, Stanford, Chris, Westerdale, Shawn, Calaprice, Frank, Wright, Alexander, and Shi, Zhiming. Tue . "First measurement of surface nuclear recoil background for argon dark matter searches". United States. doi:10.1103/PhysRevD.96.061101.
@article{osti_1426118,
title = {First measurement of surface nuclear recoil background for argon dark matter searches},
author = {Xu, Jingke and Stanford, Chris and Westerdale, Shawn and Calaprice, Frank and Wright, Alexander and Shi, Zhiming},
abstractNote = {Here, one major background in direct searches for weakly interacting massive particles (WIMPs) comes from the deposition of radon progeny on detector surfaces. A dangerous surface background is the 206Pb nuclear recoils produced by 210Po decays. In this paper, 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 103 keV 206Pb recoil background will produce a signal equal to that of a ~5 keV (30 keV) electron recoil (40Ar recoil). In addition, we demonstrate that this dangerous 210Po surface background can be suppressed, using pulse shape discrimination methods, by a factor of ~100 or higher, which can make argon dark matter detectors near background-free and enhance their potential for discovery of medium- and high-mass WIMPs. Lastly, we also discuss the impact on other low background experiments.},
doi = {10.1103/PhysRevD.96.061101},
journal = {Physical Review D},
number = 6,
volume = 96,
place = {United States},
year = {Tue Sep 19 00:00:00 EDT 2017},
month = {Tue Sep 19 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
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  • The Argon Dark Matter (ArDM) experiment consists of a liquid argon (LAr) time projection chamber (TPC) sensitive to nuclear recoils, resulting from scattering of hypothetical Weakly Interacting Massive Particles (WIMPs) on argon targets. With an active target mass of 850 kg ArDM represents an important milestone towards developments for large LAr Dark Matter detectors. Here we present the experimental apparatus currently installed underground at the Laboratorio Subterráneo de Canfranc (LSC), Spain. We show data on gaseous or liquid argon targets recorded in 2015 during the commissioning of ArDM in single phase at zero E-field (ArDM Run I). The data confirmsmore » the overall good and stable performance of the ArDM tonne-scale LAr detector.« less
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  • The coherent contribution of all neutrons in neutrino nucleus scattering due to the neutral current is examined considering the boron solar neutrinos. These neutrinos could potentially become a source of background in the future dark matter searches aiming at nucleon cross sections in the region well below the 10{sup -10} pb, i.e a few events per ton per year.
  • We compare the measured angular cross-correlation between the Fermi-Large Area Telescope γ-ray sky and catalogs of extragalactic objects with the expected signal induced by weakly interacting massive particle (WIMP) dark matter (DM). We include a detailed description of the contribution of astrophysical γ-ray emitters such as blazars, misaligned active galactic nucleus (AGN), and star-forming galaxies, and perform a global fit to the measured cross-correlation. Five catalogs are considered: Sloan Digital Sky Survey (SDSS)-DR6 quasars, Two Micron All Sky Survey galaxies, NRAO VLA Sky Survey radio galaxies, SDSS-DR8 Luminous Red Galaxies, and the SDSS-DR8 main galaxy sample. To model the cross-correlation signal,more » we use the halo occupation distribution formalism to estimate the number of galaxies of a given catalog in DM halos and their spatial correlation properties. We discuss uncertainties in the predicted cross-correlation signal arising from the DM clustering and WIMP microscopic properties, which set the DM γ-ray emission. The use of different catalogs probing objects at different redshifts significantly reduces, though not completely, the degeneracy among the different γ-ray components. We find that the presence of a significant WIMP DM signal is allowed by the data but not significantly preferred by the fit, although this is mainly due to a degeneracy with the misaligned AGN component. With modest substructure boost, the sensitivity of this method excludes thermal annihilation cross sections at 95% level for WIMP masses up to few tens of GeV. Constraining the low-redshift properties of astrophysical populations with future data will further improve the sensitivity to DM.« less