Studies of the Response of the SiD Silicon-Tungsten ECal

TL;DR

This study evaluates the SiD silicon-tungsten electromagnetic calorimeter's ability to separate electromagnetic showers using a prototype tested at SLAC, with results showing high separation efficiency and ongoing calibration development.

Contribution

It presents the first detailed test of a highly granular SiD ECal prototype and compares experimental data with Geant4 simulations, advancing calibration methods.

Findings

Achieved 98.5% separation efficiency for electrons at least 1 cm apart

Validated Geant4 simulation against beam test data

Developing energy, angle, and depth-dependent calibration constants

Abstract

Studies of the response of the SiD silicon-tungsten electromagnetic calorimeter (ECal) are presented. Layers of highly granular (13 mm^2 pixels) silicon detectors embedded in thin gaps (~ 1 mm) between tungsten alloy plates give the SiD ECal the ability to separate electromagnetic showers in a crowded environment. A nine-layer prototype has been built and tested in a 12.1 GeV electron beam at the SLAC National Accelerator Laboratory. This data was simulated with a Geant4 model. Particular attention was given to the separation of nearby incident electrons, which demonstrated a high (98.5%) separation efficiency for two electrons at least 1 cm from each other. The beam test study will be compared to a full SiD detector simulation with a realistic geometry, where the ECal calibration constants must first be established. This work is continuing, as the geometry requires that the calibration constants depend upon energy, angle, and absorber depth. The derivation of these constants is being developed from first principles.