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 Ne−CO2(90−10) and Ar−CH4(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.
Cite
@article{arxiv.1603.05648,
title = {Simulations of a multi-layer extended gating grid},
author = {J. D. Mulligan},
journal= {arXiv preprint arXiv:1603.05648},
year = {2016}
}