Micro pattern gas detector optical readout for directional dark matter searches

Abstract The Time Projection method is ideal to track low kinetic energy charged particles, in particular for the study for Dark Matter interactions. With this technique we aim to readout large volumes with a moderate number of channels providing a complete 3D reconstruction of the tracks within the sensitive region. The total released energy and the energy density along the tracks can be both measured allowing for particle identification and to solve the head-tail ambiguity of the track. Moreover, in gas, nuclear recoils induced by a Dark Matter particle scattering can yield tracks long enough for its direction to be inferred. We describe here a prototype TPC with a GEM amplification stage. The readout is based on the detection of the light produced in the GEM with a high granularity sCMOS sensor in conjunction with a photomultiplier. The prototype was exposed to γ and neutron source and to minimum ionizing particles, obtaining very promising results in terms of detection efficiency, energy resolution and particle identification.