Relative Measurement and Extrapolation of the Scintillation Quenching Factor of $\alpha$-Particles in Liquid Argon using DEAP-3600 Data

TL;DR

This study measures how alpha particles' scintillation light is quenched in liquid argon using data from the DEAP-3600 detector, aiding dark matter detection by understanding background signals.

Contribution

It provides a relative measurement of alpha particle quenching in liquid argon and assesses the uncertainty in extrapolating to low energies, which was previously not well characterized.

Findings

Measured scintillation quenching factors for alpha particles in liquid argon.

Quantified uncertainty in extrapolating quenching factors to low energies.

Improved understanding of alpha-induced backgrounds in dark matter detectors.

Abstract

The knowledge of scintillation quenching of $\alpha$-particles plays a paramount role in understanding $\alpha$-induced backgrounds and improving the sensitivity of liquid argon-based direct detection of dark matter experiments. We performed a relative measurement of scintillation quenching in the MeV energy region using radioactive isotopes ($^{222}$Rn, $^{218}$Po and $^{214}$Po isotopes) present in trace amounts in the DEAP-3600 detector and quantified the uncertainty of extrapolating the quenching factor to the low-energy region.