Title: Cathode signal in a TPC directional detector: implementation and validation measuring the drift velocity,
Abstract: Low-pressure gaseous TPCs are well suited detectors to correlate the
directions of nuclear recoils to the galactic Dark Matter (DM) halo. Indeed, in
addition to providing a measure of the energy deposition due to the elastic
scattering of a DM particle on a nucleus in the target gas, they allow for the
reconstruction of the track of the recoiling nucleus. In order to exclude the
background events originating from radioactive decays on the surfaces of the
detector materials within the drift volume, efforts are ongoing to precisely
localize the track nuclear recoil in the drift volume along the axis
perpendicular to the cathode plane. We report here the implementation of the
measure of the signal induced on the cathode by the motion of the primary
electrons toward the anode in a MIMAC chamber. As a validation, we performed an
independent measurement of the drift velocity of the electrons in the
considered gas mixture, correlating in time the cathode signal with the measure
of the arrival times of the electrons on the anode.