Ring-like features in directional dark matter detection

Abstract

We discuss a novel dark matter signature relevant for directional detection\nof Weakly Interacting Massive Particles (WIMPs). For heavy enough WIMPs and low\nenough recoil energies, the maximum of the recoil rate is not in the direction\nof the average WIMP arrival direction but in a ring around it at an angular\nradius that increases with the WIMP mass and can approach 90 degrees at very\nlow energies. The ring is easier to detect for smaller WIMP velocity dispersion\nand larger average WIMP velocities relative to the detector. In principle the\nring could be used as an additional indication of the WIMP mass range.\n