Complementarity of Dark Matter Direct Detection Targets

TL;DR

This paper assesses how future direct detection experiments using different target materials can jointly improve the reconstruction of Dark Matter properties, despite astrophysical uncertainties, highlighting the benefits of target complementarity.

Contribution

It quantifies the complementarity of germanium, xenon, and argon detectors in reconstructing Dark Matter parameters and explores how astrophysical uncertainties impact these measurements.

Findings

Combining multiple targets improves parameter constraints by a factor of two.

Astrophysical uncertainties can degrade mass reconstruction accuracy by up to a factor of four.

Future experiments can self-calibrate astrophysical parameters and constrain WIMP mass with minimal external data.

Abstract

We investigate the reconstruction capabilities of Dark Matter mass and spin-independent cross-section from future ton-scale direct detection experiments using germanium, xenon or argon as targets. Adopting realistic values for the exposure, energy threshold and resolution of Dark Matter experiments which will come online within 5 to 10 years, the degree of complementarity between different targets is quantified. We investigate how the uncertainty in the astrophysical parameters controlling the local Dark Matter density and velocity distribution affects the reconstruction. For a 50 GeV WIMP, astrophysical uncertainties degrade the accuracy in the mass reconstruction by up to a factor of $\sim 4$ for xenon and germanium, compared to the case when astrophysical quantities are fixed. However, combination of argon, germanium and xenon data increases the constraining power by a factor of $\sim 2$ compared to germanium or xenon alone. We show that future direct detection experiments can achieve self-calibration of some astrophysical parameters, and they will be able to constrain the WIMP mass with only very weak external astrophysical constraints.