Features of the gas discharge in the narrow gap micro-pattern gas detectors (MPGD) at a high level of alpha-particles background

TL;DR

This paper investigates electron multiplication in micro-pattern gas detectors under high alpha-particle background, revealing complex streamer mode phenomena and proposing a new gas mixture for spark protection.

Contribution

It expands understanding of streamer mode in MPGD and introduces a novel gas composition to prevent spark breakdown at high alpha backgrounds.

Findings

Streamer mode involves plasma oscillations and ionization waves.

A new gas mixture (70% He, 28% CF4, 2% SF6) enhances spark protection.

Preliminary results show effective electron multiplication under challenging conditions.

Abstract

In given article preliminary results of the research of the electron multiplication in MPGD are presented at a high level of alpha-particles background. This work has expanded borders of understanding of the streamer mode nature. It is seen as a complex from electrostatic and electromagnetic interactions which begin with appearance of the precursor in plasma state. In an inter-electrode gap the plasma oscillations occur, accompanied by longitudinal elastic waves of ionization, which can reach the cathode surface with induced negative charge. With the release of this charge due to previously established conducting channel there is a strong current pulse, accompanied by the emission due to recombination of positive and negative ions and a thin cord or streamer derive. In the aim of the MPGD protection from the spark breakdown at a high level of the alpha-particle background the next gas composition from a buffer, cooling and electronegative components are offered: 70% He +28% CF4 +2% SF6.