Cathode signal in a TPC directional detector: implementation and validation measuring the drift velocity

TL;DR

This paper presents a method to measure the cathode signal in a TPC detector to accurately determine electron drift velocity, aiding in background event localization for dark matter detection.

Contribution

It introduces a new implementation for measuring cathode signals and validates it through independent drift velocity measurements in a TPC detector.

Findings

Successful measurement of cathode signals correlated with electron arrival times

Accurate drift velocity measurement in the specified gas mixture

Enhanced localization of nuclear recoil tracks for dark matter searches

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.