Measurement of the range component directional signature in a DRIFT-II detector using ²⁵²Cf neutrons

The Directional Recoil Identification From Tracks (DRIFT) collaboration utilizes low-pressure gaseous detectors to search for Weakly Interacting Massive Particle (WIMP) dark matter with directional signatures. A ²⁵²Cf neutron source was placed on each of the principal axes of a DRIFT detector in order to test its ability to measure directional signatures from the three components of very low-energy (∼keV/amu) recoil ranges. A high trigger threshold and the event selection procedure ensured that only sulfur recoils were analyzed. Sulfur recoils produced in the CS₂ target gas by the ²⁵²Cf source closely match those expected from massive WIMP induced sulfur recoils. For each orientation of the source, with a threshold of ∼50 keV, a directional signal from the range components was observed, indicating that the detector has directional capability along all three axes, though in one direction the directionality was marginal. An analysis of these results yields an optimal orientation for DRIFT detectors when searching for a directional signature from WIMPs. Additional energy dependent information is provided to aid in understanding this effect.