CYGNUS: development of a high resolution TPC for rare events

The \(R\&D\) of a gas detector prototype for high precision tracking of low energy nuclear recoils over large volume is presented in this paper. The scintillation light accompanying the electronic avalanches in a triple GEM structure is detected by a CMOS-based camera. The sensor provides very high granularity along with a very low noise and high sensitivity. Space resolution of the order of tens of \(\mu\)m were measured on the GEM plane (\({\it x,y}\)). The Negative Ion Drift method to reconstruct the depth of track within the sensitive volume was studied. Recent tests on beam demonstrated the feasibility of the NID method with a small amount of SF$_6$ even at nearly ambient pressure. The use of a concurrent light readout by means of a suitable photomultiplier provides the necessary timing informations. A time resolution of the order of 5 ns was measured