Speaker
Description
The Recoil Directionality (ReD) experiment aims to investigate the directional sensitivity of argon-based Time Projection Chambers (TPCs) via columnar recombination to nuclear recoils in the energy range of interest (20–200 keV) for direct dark matter searches. Directional information is an essential requisite for correlating a candidate dark matter signal with the expected “wind” of dark matter from the Cygnus constellation. As part of the DarkSide programme, the ReD collaboration has designed and constructed a double-phase argon TPC and fully characterised its performance using various gamma-ray and neutron sources. The key novel feature of the ReD TPC is a readout system based on cryogenic Silicon Photomultipliers (SiPMs), which offer a higher photon detection efficiency relative to typical cryogenic photomultipliers. Here we report on measurements of the scintillation light yield and ionization gain performed over five months of continuous operation. We present a phenomenological parameterisation of the electron-ion recombination probability in liquid argon (LAr) that describes the anti-correlation between scintillation and ionisation signals measured by ReD as a function of drift field for electron recoils between 50–500 keV and fields up to 1000 V/cm. Finally, a likelihood analysis is performed in order to study the directional response of the ReD TPC to neutrons of known energy and direction.
