Background Studies for an Accelerator-Based Dark Matter Search

The unknown composition of dark matter has always been one of the most intriguing problems in physics. Absence of theoretical and experimental support for Weakly Interacting Massive Particle (WIMP) has focused attention to another dark matter candidate, Light Dark Matter at Accelerators (LDMA). The Directional Recoil Identification From Tracks (DRIFT) project has developed highly sensitive detectors to detect the directionally sensitive ionization created by recoils, an ideal detector for low energy recoils by LDMA. Neutron recoils due to cosmic-ray induced muons and neutrons are one of the most important backgrounds in DRIFT. We have been exploring the backgrounds in DRIFT-IIf, the current detector, under different shielding conditions, including concrete building structures and outdoor sites. Experiments are compared with simulations on GEANT4. Our results show that DRIFT is only sensitive to neutron recoils despite large muon and gamma backgrounds from cosmic rays on the surface. Neutron recoil results will be presented for a detector unshielded, under various thickness of concrete and a lead shield exposed to cosmic rays at the surface.