Speaker
Description
A powerful beacon for penetrating the Neutrino Fog obscuring direct detection of heavy dark matter would be direction-sensitive detection of the recoil atoms. Negative-ion drift is being pursued for this purpose by a number of collaborations, but it is hard to see how this could achieve sensitive mass competitive with noble liquid TPCs. Direction sensitivity based on columnar recombination differences with respect to the electric drift field is well established for higher energy tracks in LAr. However, attempts to observe it in the liquid have not yielded statistically significant positive results. However, a 1994 experiment drifting charged tracks in LAr in the presence of a magnetic field as well, revealed substantial electron (v×B) drift, abeit operating at elevated temperature and pressure (T ≥ 120 K, P ≥ 26 bar). This result would imply a sufficiently long mean free path for drifting charge to show a columnar recombination based directional effect. The physics background and prospects for seeking this effect will be discussed.
