Analytic approximation of energy resolution in cascaded gaseous detectors

TL;DR

This paper derives an approximate analytical formula for energy resolution in cascaded gaseous detectors, validated experimentally with a GEM setup, aiding interpretation and simulation of multi-GEM systems.

Contribution

It introduces a new analytic approximation for gain fluctuations in cascaded gaseous detectors, validated through experimental measurements.

Findings

The formula accurately models charge collection and extraction effects on energy resolution.

Experimental results agree with the theoretical approximation.

The approach can be applied to interpret and simulate multi-GEM detector performance.

Abstract

An approximate formula has been derived for gain fluctuations in cascaded gaseous detectors such as GEM-s, based on the assumption that the charge collection, avalanche formation and extraction steps are independent cascaded processes. In order to test the approximation experimentally, a setup involving a standard GEM layer has been constructed to measure the energy resolution for 5.9 keV gamma particles. The formula reasonably traces both the charge collection as well as the extraction process dependence of the energy resolution. Such analytic approximation for gain fluctuations can be applied to multi-GEM detectors where it aids the interpretation of measurements as well as simulations.