Electromagnetic Shower Recognition with a Forward Calorimeter for the ALICE Experiment

Abstract

This work deals with discriminating between electromagnetic showers induced by high-energy single photons and those induced by the double photon decays originating from high-energy neutral pions. The preliminary design of a hybrid detector is employed, which is intended for use as an electromagnetic calorimeter in the forward region of the ALICE experimental setup at CERN. The calorimeter combines conventional, low-granularity sensors with non-conventional high-granularity sensors. Results from simulations are systematically studied, revealing that the high-granularity technology is essential for separating photon pairs originating from neutral pions and for identifying these decays based on invariant mass analysis. Further improvements enabled by shower shape analysis for unseparated photon pairs are explored. The study shows that a specific procedure for processing the response of the high-granularity component is required in order for its effective use in shower shape analysis. The performance of the detector is evaluated in the context of proton- proton collisions, emphasizing the advantage of high-granularity technology, the interplay between invariant mass analysis and shower shape analysis, as well as the complementarity of low-granularity and high-granularity information for shower shape analysis.