GEANT4-Based Comparative Study of Detector Response in Reduced and Fully Instrumented Silicon-Tungsten Sampling Calorimeter
{A GEANT4-based simulation study of a silicon--tungsten (Si--W) sampling calorimeter is presented to investigate electromagnetic shower development and detector response in the energy range of 1--120 GeV. Two detector configurations are considered: a reduced sequential-sampling prototype (Configuration-I), where a single silicon detector layer is placed downstream of progressively increasing tungsten absorber depths to sample the longitudinal shower evolution, and a fully instrumented sampling calorimeter (Configuration-II) consisting of twenty silicon layers interleaved with tungsten absorbers. The detector response is studied in terms of longitudinal shower development, shower maximum position, energy deposition, detector linearity, and calorimetric performance. Configuration-II provides simultaneous longitudinal sampling and allows event-by-event reconstruction of the deposited energy, yielding the expected linear response and energy resolution. Configuration-I reproduces the average longitudinal shower profiles and exhibits a strong linear correlation with the integrated shower response of Configuration-II. Although the absence of event-by-event multi-layer sampling prevents a direct determination of calorimetric energy resolution in Configuration-I, the observed correlation between two configurations is used to relate the response of the reduced prototype to that of the fully instrumented calorimeter and to estimate the corresponding calorimetric performance. The results demonstrate that the reduced prototype successfully reproduces the main characteristics of electromagnetic shower development observed in the fully instrumented detector, establishing its usefulness for detector characterization and test-beam studies when the construction of a complete prototype is limited by available resources.