The DRIFT Project: Searching for WIMPS with a Directional Detector

A low pressure time projection chamber for the detection of WIMPs is discussed. Discrimination against Compton electron background in such a device should be very good, and directional information about the recoil atoms would be obtainable. If a full 3-D reconstruction of the recoil tracks can be achieved, Monte Carlo studies indicate that a WIMP signal could be identified with high confidence from as few as 30 detected WIMP-nucleus scattering events. To identify a WIMP signal, conventional searches rely mainly on searching for an annual modulation in the rate of nuclear recoils in the detector. This arises from the varying combined velocity vectors of the Earth’s orbital motion and the Galactic rotation [1]. Because this is only a 5% effect, and existing detectors generally have a large background from Compton electrons, many WIMP-nucleus scattering events are needed to identify a WIMP signal statistically. Therefore emphasis has mainly been placed on 1 E-mail: [email protected]