Simulations of a multi-layer extended gating grid

TL;DR

This paper explores a multi-layer extended gating grid design to suppress ion back-flow in time projection chambers, analyzing its impact on live time and electron transparency through detailed simulations for ALICE and STAR detectors.

Contribution

It introduces a novel multi-layer gating grid concept and provides simulation results on its effectiveness for ion back-flow suppression and electron transparency.

Findings

Achieves 75% live time with 86% electron transparency for ALICE.

Achieves 95% live time with 83% electron transparency for STAR.

Analyzes effects of mesh vs. wire-plane grid, magnetic field, and voltage distribution.

Abstract

A novel idea to control ion back-flow in time projection chambers is to use a multi-layer extended gating grid to capture back-flowing ions at the expense of live time and electron transparency. In this initial study, I perform simulations of a four-layer grid for the ALICE and STAR time projection chambers, using $\text{Ne}-\text{CO}_{2}\;(90-10)$ and $\text{Ar}-\text{CH}_{4}\;(90-10)$ gas mixtures, respectively. I report the live time and electron transparency for both 90% and 99% ion back-flow suppression. Additionally, for the ALICE configuration I study several effects: using a mesh vs. wire-plane grid, including a magnetic field, and varying the over-voltage distribution in the gating region. For 90% ion back-flow suppression, I achieve 75% live time with 86% electron transparency for ALICE, and 95% live time with 83% electron transparency for STAR.