Direction dependence and diurnal modulation in dark matter detectors

In this paper we study the effect of the channeling of ions recoiling from collisions with weakly interacting massive particles (WIMPs) in single crystal detectors. In particular we investigate the possibility that channeling may give rise to diurnal modulations of the counting rate as the Earth rotates relative to the direction of the WIMP wind, and the effect that channeling has on the “quenching factor” of a detector.

► The recoil spectrum of WIMPS in single crystal detectors is calculated using a simple model of channeling.
► Channeling is found to significantly enhance the quenching factor of the detector, but does not lead to significant diurnal modulation of the counting rate.
► The quenching factor is especially important when considering light wimps, Mx∼10 GeV, as this leads to a lower effective energy threshold for the detector.