Fabrication and beam test of a silicon-tungsten electromagnetic calorimeter

TL;DR

This paper reports on the construction and beam testing of a silicon-tungsten electromagnetic calorimeter, demonstrating its linear response and energy resolution for electrons in a wide energy range at CERN SPS.

Contribution

The study presents a novel silicon-tungsten sampling calorimeter with detailed characterization and performance evaluation using high-energy pion and electron beams.

Findings

Calorimeter shows linear energy response up to 60 GeV.

Measured energy resolution follows  = (15.36/^{0.5}  2.0)% for selected events.

Successful demonstration of calorimeter's performance for electromagnetic shower measurements.

Abstract

A silicon-tungsten (Si-W) sampling calorimeter, consisting of 19 alternate layers of silicon pad detectors (individual pad area of 1~cm$^2$) and tungsten absorbers (each of one radiation length), has been constructed for measurement of electromagnetic showers over a large energy range. The signal from each of the silicon pads is readout using an ASIC with a dynamic range from $-300$~fC to $+500$~fC. Another ASIC with a larger dynamic range, $\pm 600$~fC has been used as a test study. The calorimeter was exposed to pion and electron beams at the CERN Super Proton Synchrotron (SPS) to characterise the response to minimum ionising particles (MIP) and showers from electromagnetic (EM) interactions. Pion beams of 120 GeV provided baseline measurements towards the understanding of the MIP behaviour in the silicon pad layers, while electron beams of energy from 5 GeV to 60 GeV rendered detailed shower profiles within the calorimeter. The energy deposition in each layer, the longitudinal shower profile, and the total energy deposition have been measured for each incident electron energy. Linear behaviour of the total measured energy ($E$) with that of the incident particle energy ($E_{0}$) ensured satisfactory calorimetric performance. For a subset of the data sample, selected based on the cluster position of the electromagnetic shower of the incident electron, the dependence of the measured energy resolution on $E_{0}$ has been found to be $\sigma/E = (15.36/\sqrt{E_0(\mathrm{GeV)}} \oplus 2.0) \%$.