Angular resolution of the MIMAC Dark Matter directional detector

Non-baryonic Dark Matter (DM) in the form of Weakly Interacting Massive Particles (WIMPs) is the most privileged scenario for these elusive particles. WIMPs should interact with the nuclei of the active volume of detectors. If a robust signal is eventually observed in direct detection experiments, the best signature to confirm its Galactic origin would be the nuclear recoil track direction. In order to get this directional signature, the directional Dark Matter detectors should be sensitive to low energy recoils in the keV range and have an angular resolution better than $20^{\circ}$. The MIMAC collaboration has developed a low pressure gas detector which provides both the kinetic energy and three-dimensional track reconstruction of nuclear recoil tracks. We have performed experiments using a low energy ($1$-$25$ keV) ion beam facilities to measure the angular nuclear recoil track response of the MIMAC detector. In this paper we report the first ever observations of $^{19}$F nuclei tracks in this low energy range. We have studied the recoil track lengths (depths), widths and angular spreads with respect to a known incoming reference direction. The estimated angular resolution is better than $8^{\circ}$ at $10$ keV kinetic energy. These results are showing that a directional signature from the Galactic origin of a Dark Matter WIMP signal is accessible