Improved measurement of the head-tail effect in nuclear recoils

Abstract

We present new results with a prototype detector that is being developed by the DMTPC collaboration for the measurement of the direction tag (head-tail) of dark matter wind. We use neutrons from a Cf-252 source to create low-momentum nuclear recoils in elastic scattering with the residual gas nuclei. The recoil track is imaged in low-pressure time-projection chamber with optical readout. We measure the ionization rate along the recoil trajectory, which allows us to determine the direction tag of the incoming neutrons.

Contributed to the International Conference on Topics in Astroparticle and Underground Physics (TAUP) 2007, Sendai, Japan (3 pages, 4 figures)