Lowering the Threshold in the DAMA Dark Matter Search

TL;DR

The paper discusses how lowering the detection threshold in the DAMA dark matter experiment can help distinguish between different WIMP mass ranges and interaction types, improving the understanding of dark matter signals.

Contribution

It analyzes the impact of recent detector upgrades allowing lower thresholds on the interpretation of DAMA's modulation signal, potentially ruling out certain WIMP mass ranges.

Findings

Lower thresholds can disfavor one WIMP mass range by over 2.6σ.

Data may differentiate between spin-independent and spin-dependent interactions.

Enhanced sensitivity improves dark matter parameter space constraints.

Abstract

The DAMA experiment searches for Weakly Interacting Massive Particle (WIMP) dark matter via its expected but rare interactions within the detector, where the interaction rates will modulate throughout the year due to the orbital motion of the Earth. Over the course of more than 10 years of operation, DAMA has indeed detected a strong modulation in the event rate above the detector threshold of 2 keVee. Under standard assumptions regarding the dark matter halo and WIMP interactions, this signal is consistent with that expected of WIMPs of two different approximate masses: ~ 10 GeV and ~ 70 GeV. We examine how a lower threshold, allowed by recent upgrades to the DAMA detector, may shed light on this situation. We find that the lower threshold data should rule out one of the two mass ranges for spin-independent couplings (in the worst case, disfavoring one of the masses by still more than 2.6$\sigma$) and is likely, though not certain, to do the same for spin-dependent couplings. Furthermore, the data may indicate whether the interaction is predominantly spin-independent or spin-dependent in some cases. Our findings illustrate the importance of a low threshold in modulation searches.