The ALICE TPC

We describe the ALICE TPC, with emphasis on the design features which are driven by the physics requirements of the detector. In particular, the gas choice and composition, Ne–CO2 [90-10], as well as the unprecedentedly high gain for a TPC ( 2 × 10 40 ) , are direct consequences of the expected performance in the high-multiplicity environment of heavy-ion collisions at the LHC. The characteristics of this mixture are discussed and a viable way of improving the stability of detectors working under these conditions, namely the addition of nitrogen into the mixture, is presented. This results in a more effective Penning transfer of neon excited states onto ionisation of the quencher at no penalty for the charge transport and amplification properties.