Direct dark matter detection: The diurnal variation in directional experiments

TL;DR

This paper explores how directional dark matter detection experiments can observe a daily diurnal variation in signal due to Earth's rotation, providing a potential signature for dark matter detection.

Contribution

It provides theoretical analysis of the diurnal variation in directional dark matter detection experiments, highlighting the importance of Earth's rotation in signal modulation.

Findings

Detection rate varies periodically during the day.

The diurnal variation depends on the observation angle.

Directional experiments can identify dark matter signals through daily modulation.

Abstract

We present some theoretical results relevant to the direct dark matter detection experiments, paying particular attention to directional experiments, i.e. experiments in which, not only the energy but the direction of the recoiling nucleus is observed. In directional experiments the detection rate depends on the angle between the line observation and the sun's direction of motion. Since, however, the direction of observation is fixed with respect the earth, while the Earth is rotating around its axis, in a directional experiment the angle between the direction of observation and the Sun's direction of motion will change during the day. So the observed signal in such experiments will exhibit a very interesting and characteristic periodic diurnal variation.