Solar neutrinos and dark matter detection with diurnal modulation

TL;DR

This paper explores how diurnal modulation of event rates can improve dark matter detection by distinguishing signals from neutrino backgrounds, especially in germanium detectors, and assesses the impact of timing information on experimental sensitivity.

Contribution

It introduces a method to utilize diurnal modulation effects for separating dark matter signals from neutrino backgrounds and evaluates its effectiveness in germanium detectors.

Findings

Diurnal modulation enhances detection sensitivity for light dark matter.

Timing information improves the ability to distinguish dark matter signals from backgrounds.

Using both annual and diurnal modulation provides a modest increase in experimental reach.

Abstract

We investigate the diurnal modulation of the event rate for dark matter scattering on solid targets arising from the directionally dependent defect creation threshold energy. In particular, we quantify how this effect would help in separating dark matter signal from the neutrino background. We perform a benchmark analysis for a germanium detector and compute how the reach of the experiment is affected by including the timing information of the scattering events. We observe that for light dark matter just above the detection threshold the magnitude of the annual modulation is enhanced. In this mass range using either the annual or diurnal modulation information provides a similar gain in the reach of the experiment, while the additional reach from using both effects remains modest. Furthermore, we demonstrate that if the background contains a feature exhibiting an annual modulation similar to the one observed by DAMA experiment, the diurnal modulation provides for an additional handle to separate dark matter signal from the background.