Charge Distribution Dependency on Gap Thickness of CMS Endcap RPC

TL;DR

This study systematically investigates how the charge distribution in CMS Resistive Plate Chambers depends on the gap thickness, revealing that smaller gaps produce smaller charges and highlighting the impact of electric field strength and space charge effects.

Contribution

The paper presents experimental data on charge distributions across various gap thicknesses in RPCs, providing insights into optimizing detector performance.

Findings

Charge distribution varies with gap thickness.

Smaller gaps produce smaller charges.

Space charge effects are observed at higher voltages.

Abstract

We report a systematic study of charge distribution dependency of CMS Resistive Plate Chamber (RPC) on gap thickness. Prototypes of double-gap RPCs with six different gap thickness ranging from from 1.0 to 2.0 mm in 0.2-mm steps have been built with 2-mm-thick phenolic high-pressure-laminated plates. The efficiencies of the six gaps are measured as a function of the effective high voltages. We report that the strength of the electric fields of the gap is decreased as the gap thickness is increased. The distributions of charges in six gaps are measured. The space charge effect is seen in the charge distribution at the higher voltages. The logistic function is used to fit the charge distribution data. Smaller charges can be produced within smaller gas gap. But the digitization threshold should be also lowered to utilize these smaller charges.