Measurement of the Gamma Ray Background in the Davis Cavern at the Sanford Underground Research Facility

Abstract

Deep underground environments are ideal for low background searches due to the attenuation of cosmic rays by passage through the earth. However, they are affected by backgrounds from $\gamma$-rays emitted by ${}^{40}$K and the ${}^{238}$U and ${}^{232}$Th decay chains in the surrounding rock. The LUX-ZEPLIN (LZ) experiment will search for dark matter particle interactions with a liquid xenon TPC located within the Davis campus at the Sanford Underground Research Facility, Lead, South Dakota, at the 4,850-foot level. In order to characterise the cavern background, in-situ $\gamma$-ray measurements were taken with a sodium iodide detector in various locations and with lead shielding. The integral count rates (0--3300~keV) varied from 596~Hz to 1355~Hz for unshielded measurements, corresponding to a total flux in the cavern of $1.9\pm 0.4$~$\gamma$cm${}^{-2}$s${}^{-1}$. The resulting activity in the walls of the cavern can be characterised as $220\pm 60$~Bq/kg of ${}^{40}$K, $29\pm 15$~Bq/kg of ${}^{238}$U, and $13\pm 3$~Bq/kg of ${}^{232}$Th.

arXiv comment11 pages, 9 figures

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Cited by in corpus (13)

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• The LUX-ZEPLIN (LZ) radioactivity and cleanliness control programs
• A Review of Basic Energy Reconstruction Techniques in Liquid Xenon and Argon Detectors for Dark Matter and Neutrino Physics Using NEST
• Simulations of Events for the LUX-ZEPLIN (LZ) Dark Matter Experiment
• Projected sensitivity of the LUX-ZEPLIN experiment to the $0\nu \beta \beta$ decay of ${}^{136}$Xe
• Background Determination for the LUX-ZEPLIN (LZ) Dark Matter Experiment
• First Constraints on WIMP-Nucleon Effective Field Theory Couplings in an Extended Energy Region From LUX-ZEPLIN
• A Liquid Scintillation Detector for Radioassay of Gadolinium-Loaded Liquid Scintillator for the LZ Outer Detector
• Projected sensitivity of the LUX-ZEPLIN (LZ) experiment to the two-neutrino and neutrinoless double beta decays of ${}^{134}$Xe
• In-situ gamma-ray background measurements for next generation CDEX experiment in the China Jinping Underground Laboratory
• Ultra-Low Background Germanium Assay at the Boulby Underground Laboratory
• Probing the Scalar WIMP-Pion Coupling with the first LUX-ZEPLIN data