Measurements and calculations of electron avalanche growth in ternary mixture of Ne-CO2-N-2

Abstract

A Time Projection Chamber (TPC) is an ideal device for three-dimensional tracking. It is used in many experiments including ALICE at LHC. The choice of the gas mixture is crucial for this type detector performance. For the operation of the TPC at ALICE, Ne-CO2-N-2 was chosen. Because of the relatively low primary ionisation of Ne, the readout chambers have to be operated at high gas gains near 10(4). Therefore gas gain factor has been measured and calculated for this mixture. The Diethorn, Williams and Sara and of Aoyama models of the first Townsend coefficient have been used to determine the basic gas properties. Photon feedback parameters and Penning transfer rates have been also determined.