Comparison of Bulk Micromegas with Different Amplification Gaps

TL;DR

This study compares standard 128-micron gap bulk Micromegas detectors with larger 192-micron gap variants, evaluating their performance through experiments and simulations for future TPC applications.

Contribution

It provides a detailed experimental and numerical comparison of two Micromegas detector configurations with different amplification gaps.

Findings

Similar gas gain and energy resolution for both gaps

Larger gap shows slightly higher electron transparency

Simulations agree well with experimental results

Abstract

The bulk Micromegas detector is considered to be a promising candidate for building TPCs for several future experiments including the projected linear collider. The standard bulk with a spacing of 128 micron has already established itself as a good choice for its performances in terms of gas gain uniformity, energy and space point resolution, and its capability to efficiently pave large readout surfaces with minimum dead zone. The present work involves the comparison of this standard bulk with a relatively less used bulk Micromegas detector having a larger amplification gap of 192 micron. Detector gain, energy resolution and electron transparency of these Micromegas have been measured under different conditions in various argon based gas mixtures to evaluate their performance. These measured characteristics have also been compared in detail to numerical simulations using the Garfield framework that combines packages such as neBEM, Magboltz and Heed. Further, we have carried out another numerical study to determine the effect of dielectric spacers on different detector features. A comprehensive comparison of the two detectors has been presented and analyzed in this work.