Transition condition to the SQS mode of gas counters for heavy charged particles

A transition condition of /spl alpha/-ray induced SQSs has been investigated with various gas mixtures. For this purpose, obtainable experimental data have been analyzed through a consideration of two newly-introduced quantities: "effective electric-field strength (E/sub eff/)" near primary electron avalanches and "average electron density (/spl rho//sub av/)" of ionization tracks by /spl alpha/-rays. A result of the analysis indicates that such SQS transitions may occur when the value of E/sub eff//spl middot//spl rho//sub av/ reaches a certain magnitude. Following this, transition characteristics to the SQS mode have been studied for protons around 10 MeV.