The Gain Divergence on the Transition to the Self-Quenching Streamers

Based on the observed gain divergence characteris¿ tics occuring in a gaseous detector at the transition fran the proportional to the self-quenching streamers discharge (SQS), when adquate gas fillings are used and on the role played by photoionization, a mechanism is proposed to interpret quantitatively the process. The relevant intrinsic parameters, which determine the mechanism, are the number of photons emitted by electron per cm path near the anode, W, the mean free path of VUV radiation, L, the quantum efficiency, ¿, geometrical factors, g, which are interrelated. Fran the experimental data some of those parameters are computed for the mixtures argon-isobutane and argon-isobutane-triethylamine.