Measurement of shower development and its Moli\`ere radius with a four-plane LumiCal test set-up

TL;DR

This study tests a prototype luminometer in a beam environment to analyze electromagnetic shower development and measure the Molière radius, confirming simulation accuracy with experimental data.

Contribution

First measurement of the Molière radius for a LumiCal prototype using a four-plane tungsten-silicon setup at CERN.

Findings

Molière radius measured as 24.0 mm with uncertainties.

Excellent agreement between experimental data and Geant4 simulations.

Validated the multi-plane tungsten/silicon operation for future collider detectors.

Abstract

A prototype of a luminometer, designed for a future e+e- collider detector, and consisting at present of a four-plane module, was tested in the CERN PS accelerator T9 beam. The objective of this beam test was to demonstrate a multi-plane tungsten/silicon operation, to study the development of the electromagnetic shower and to compare it with MC simulations. The Moli\`ere radius has been determined to be 24.0 +/- 0.6 (stat.) +/- 1.5 (syst.) mm using a parametrization of the shower shape. Very good agreement was found between data and a detailed Geant4 simulation.