Special gas mixtures with very small drift angles at low drift velocities

Abstract

Using the novel technique of UV laser-induced ionization, drift angles and drift velocities have been measured for various gas mixtures. In the region where the drift velocity is linearly dependent on the drift field and up to 10 kG, the measured values agree well with predictions by computations also described in this article. Two gas mixtures were found which give small drift angles at low drift velocities. This is important for the operation of a time expansion chamber (TEC).