Compact LumiCal prototype tests for future $e^+e^-$ colliders

TL;DR

This paper reports on tests of a compact LumiCal prototype designed for future electron-positron colliders, demonstrating its capabilities in measuring electron showers and validating simulations with experimental data.

Contribution

It presents the development and beam test results of a new compact LumiCal prototype with integrated electronics for precise luminosity measurements.

Findings

Successful sensor alignment and shower profile measurements

Agreement between experimental data and Geant4 simulations

Validation of the prototype's performance in a realistic beam environment

Abstract

The FCAL collaboration is preparing large-scale prototypes of special calorimeters to be used in the very forward region at future electron-positron colliders for instant luminosity measurement and a precise measurement of integrated luminosity and for assisting beam-tuning. LumiCal is designed as silicon-tungsten sandwich calorimeter with very thin sensor planes to keep the Moli\`ere radius small, thus facilitating the measurement of electron showers in the presence of background. Dedicated FE electronics has been developed to match the timing and dynamic range requirements. A partially instrumented prototype was investigated in a 1 to 5 GeV electron beam at the DESY II synchrotron. In the recent beam tests, a multi-plane compact prototype equipped with thin detector planes fully assembled with readout electronics were installed in 1 mm gaps between tungsten plates of one radiation length thickness. High statistics data were used to perform sensor alignment, and to measure the longitudinal and transversal shower development. In addition, Geant4 MC simulations were done and compared to the data.