Negative ion Time Projection Chamber operation with SF$_{6}$ at nearly atmospheric pressure

TL;DR

This study demonstrates the operation of a negative ion Time Projection Chamber using SF$_{6}$ at nearly atmospheric pressure, showing promising results for future dark matter detection technologies.

Contribution

It provides new measurements of drift velocities and mobilities of SF$_{6}$ gas mixtures and extends negative ion operation to triple thin GEMs at near atmospheric pressure.

Findings

Successful operation of negative ion TPC with SF$_{6}$ at 610 Torr

Extended negative ion operation to triple thin GEMs

Potential application in next-generation dark matter detectors

Abstract

We present measurements of drift velocities and mobilities of some innovative negative ion gas mixtures at nearly atmospheric pressure based on SF$_{6}$ as electronegative capture agent and of pure SF$_{6}$ at various pressures, performed with the NITEC detector. NITEC is a Time Projection Chamber with 5 cm drift distance readout by a GEMPix, a triple thin GEMs coupled to a Quad-Timepix chip, directly sensitive to the deposited charge on each of the 55 $\times$ 55 $\mu$m$^2$ pixel. Our results contribute to expanding the knowledge on the innovative use of SF$_{6}$ as negative ion gas and extend to triple thin GEMs the possibility of negative ion operation for the first time. Above all, our findings show the feasibility of negative ion operation with He:CF$_4$:SF$_{6}$ at 610 Torr, opening extremely interesting possibility for next generation directional Dark Matter detectors at 1 bar.