Measurement of the Muon Flux at the Sanford Underground Research Facility with the LUX-ZEPLIN Dark Matter Detector

TL;DR

This study measures the underground muon flux at the Sanford Underground Research Facility using the LUX-ZEPLIN detector over 366 days, providing crucial data for background estimation in dark matter searches.

Contribution

First measurement of muon flux at Sanford Underground Research Facility using the LUX-ZEPLIN detector with detailed energy thresholds and statistical analysis.

Findings

Muon flux measured as (5.09 ± 0.08(stat) ± 0.10(sys))×10^{-9} cm^{-2}s^{-1}

Muon rate through detector was 10.94 ± 0.17 events per day

Data helps evaluate muon-induced backgrounds in underground experiments.

Abstract

High-energy cosmic-ray muons reaching deep underground laboratories can cause events in detectors that mimic signals expected from dark matter particles, neutrinos, or rare decays. Knowledge of the muon flux and energy spectrum is important for evaluating the background rate caused by muons and their secondaries. In this paper, we report the measurement of the cosmic-ray muon flux in the Davis Campus of the Sanford Underground Research Facility with the LUX-ZEPLIN detector. Using 366.4~days of exposure, the muon rate through the detector was measured as $10.94\pm0.17_\textrm{stat.}~\textrm{day}^{-1}$ with energy thresholds of 20~MeV in the inner xenon detector and 8 MeV in the outer liquid scintillator detector. This rate corresponds to a muon flux of $(5.09\pm0.08_\textrm{stat.}\pm0.10_\textrm{sys.})\times10^{-9}~\textrm{cm}^{-2}\textrm{s}^{-1}$ in the Davis Cavern.