Self quenching streamer mode in quenching gases initiated by alpha particles

TL;DR

This study investigates the transition to self quenching streamer mode in gases like DME and isobutane caused by alpha particles, revealing a very small dead zone in DME and no second streamers in isobutane, enhancing understanding of streamer behavior.

Contribution

It provides the first detailed measurement of dead zones in DME and demonstrates the absence of second streamers in pure isobutane under alpha irradiation.

Findings

Dead zone in DME is less than 0.1 μs·cm, much smaller than noble gas mixtures.

No second streamers observed in pure isobutane for similar tracks.

Transition to streamer mode depends on track length and angle.

Abstract

The transition from a proportional to a self quenching streamer mode, as a function of track length and angle, was investigated in a single wire chamber filled with either pure DME or isobutane. The chamber was irradiated with $^{241}$Am alpha particles. An investigation of multistreamer events in DME due to alpha particles entering the chamber at 20$^\circ$ with track length 4 mm gave an estimate of a dead zone, defined as the product of dead length and dead time, to be less than 0.1 $\mu$s$\cdot$cm. This value is 3 orders of magnitude less than those observed by other groups for noble gases based mixtures. No second streamers were observed with pure isobutane for similar tracks.