Analysis of Performance of a Radiation-Hard, Highly-Segmented Shashlik Electromagnetic Calorimeter in the CERN H4 Testbeam

A shashlik style calorimeter with alternating tungsten and LYSO crystal plates underwent testbeam analysis to determine its energy resolution. A single shashlik module is a tiny rectangular prism composed of 28 2.5 mm thick tungsten plates alternating with 29 1.5 mm thick LYSO crystals, which each have a length and width of 14 mm. The expected stochastic energy resolution of this design was predicted to be ~10\%/$\sqrt{E}$ by standalone GEANT4 simulations and subsequent beam tests. A 4x4 array of shashlik modules has been tested using the H4 beamline at CERN. Following a correction to the nonlinearity of SiPM response, the energy resolution was determined.