Simulation-Rooted Assessment of Electromagnetic Calorimeters Based on Silicon Sensors

We present a Geant4-based simulation study of the electromagnetic sampling calorimeter (ECAL) foreseen in the LUXE experiment. The ECAL will enable precise measurement of the number and energy spectrum of positrons and electrons. The electromagnetic shower response, energy resolution, and linearity-properties that are essential for physics research-are studied. The Geant4 simulation model provides a good description of the data from the literature, and the stochastic energy resolution is comparable to the state-of-the-art resolution for a Si-W calorimeter. The simulated ECAL model consists of layers of solid-state sensors interspersed between tungsten plates, with the sensors divided into pads. The advantage of these detectors is their high active layer density, which facilitates the construction of more compact devices. A detailed description of the sensor response using MC simulations is fundamental to detector design and predicting energy measurement performance. We collected simulated data using electron beams in the energy range of 2 to 18 GeV, with a step of 2 GeV. The signal size distribution measured in the test beam campaign is well reproduced by the Geant4 simulation, confirming the accuracy of the simulation approach. The analysis described in this paper focuses on electromagnetic shower reconstruction and characterizes the ECAL response to electrons in terms of energy resolution and linearity.