Sensitivity projections for a dual-phase argon TPC optimized for light dark matter searches through the ionization channel

TL;DR

This paper proposes a new low-threshold argon detector design, DarkSide-LowMass, optimized for light dark matter detection via ionization, aiming to reach sensitivities near the solar neutrino floor for GeV-scale masses.

Contribution

It introduces the DarkSide-LowMass detector concept, optimized for low-threshold electron counting, and evaluates its potential sensitivity to light dark matter, including effects of backgrounds and mitigation strategies.

Findings

DarkSide-LowMass can reach sensitivities near the solar neutrino floor for GeV-scale dark matter.

Significant sensitivity down to 10 MeV/c^2 is possible considering the Migdal effect or electron interactions.

Background mitigation is crucial for achieving optimal sensitivity at low energies.

Abstract

Dark matter lighter than 10 GeV/c$^2$ encompasses a promising range of candidates. A conceptual design for a new detector, DarkSide-LowMass, is presented, based on the DarkSide-50 detector and progress toward DarkSide-20k, optimized for a low-threshold electron-counting measurement. Sensitivity to light dark matter is explored for various potential energy thresholds and background rates. These studies show that DarkSide-LowMass can achieve sensitivity to light dark matter down to the solar neutrino floor for GeV-scale masses and significant sensitivity down to 10 MeV/c$^2$ considering the Migdal effect or interactions with electrons. Requirements for optimizing the detector's sensitivity are explored, as are potential sensitivity gains from modeling and mitigating spurious electron backgrounds that may dominate the signal at the lowest energies.