GEOMETRICAL FEATURES OF ELECTRIC-LIGHT GAIN IN XENON

When one observes the scintillation light from a rare gas in an electric field one might detect some extra light. The emission time distribution of this light strongly depends on the position of the ionizing-particle path in the field. This geometrical feature of the electric-light gain (ELG) is here analysed in detail. It turns out that the ELG time distribution seen for any position of the particle (alpha in the present experiment) path can be reconduced to the distribution observed when the path is orthogonal to the field. Moreover it is proved that the ELG is produced by the electrons (among those injected by ionizing particles) which gain energy from the electric field up to the first-excitation energy, while they are travelling towards the anode with a constant average velocity. © 1968 Società Italiana di Fisica.