Directional Sensitivity, WIMP Detection, and the Galactic Halo

TL;DR

This paper introduces a new formalism to analyze directional signals in WIMP dark matter detection, emphasizing the potential to distinguish signals from background noise using angular event rates influenced by Earth's motion and galactic halo models.

Contribution

It develops a novel formalism for calculating angular event rates in WIMP detection and evaluates the number of events needed to identify dark matter signals amidst background noise.

Findings

Angular signals are stronger and less ambiguous than seasonal modulation.

Distinct recoil patterns can reveal details of the galactic halo.

Predicted signals vary across different halo models.

Abstract

Distinguishing the signals due to scattering of WIMP dark matter off of nuclear targets from those due to background noise is a major challenge. The Earth's motion relative to the galactic halo should produce halo-dependent seasonal modulation in the event rate, but it also should produce an angular signal that is both far stronger and less ambiguous. Distinct patterns in the recoil spectrum can reflect the details of the galactic halo. We derive a new formalism to calculate angular event rates, and present the predicted angular signal for a variety of halo models and calculate the number of events needed to distinguish a dark matter signal from an isotropic background.