Simulation Study of Energy Resolution of the Electromagnetic Shashlyk Calorimeter for Different of Layers and Absorber Combinations

Abstract

The response simulation of an ideal KOPIO-type electromagnetic sampling calorimeter was carried out in the energy range of 50 MeV – 16 GeV using Geant4-10.6.0 toolkit. In this work, we obtained energy resolution parameters for prototypes of Shashlyk calorimeter modules (ECAL SPD) of the NICA collider SPD setup for different thicknesses of a lead absorber with different numbers of layers. The NICA scientific experiment provides a unique opportunity to study parton distributions and correlations in hadron structure when working with high-intensity polarized relativistic ion beams. The ECAL electromagnetic calorimeter is one of the key detectors of the SPD device. There are some preliminary requirements for an electromagnetic calorimeter, in particular, for energy resolution in the energy range from 50 MeV to 16 GeV. It has been shown in detail that a more accurate obtaining of stochastic as well as permanent coefficients acting as parameters of the energy resolution parameterization formula is possible when longitudinal energy leakages from the calorimeter tower are taken into account. Such leakages are always present even in small amounts. Thus, the energy resolution parameterization of an ideal sampling calorimeter with a good χ 2/ndf value is fitted with function of the type: σE/E=(a/√E) (+)b(+)(p1ln1E+ p2ln2E + p3ln3E ) , where the logarithm lnE means ln(E/Ec), where Ec is the effective critical energy. Based on the results of detailed modeling, the dependence of these parameters on the number of calorimeter plates and absorber thicknesses was found. The approach is based on careful selection and analysis of the energy spectra obtained by modeling according to the χ-square criterion and an adequate choice of the approximation functions of the energy resolution. The methods proposed in this paper can be easily extended to other combinations of absorber-scintillator thicknesses.