Challenging the Calorimeter CALIFA for FAIR Using High Energetic Photons

Proton induced \(\gamma \)-ray reactions were used as a tool to probe and characterize a CALIFA (CALorimeter for the In-Flight detection of \(\gamma \)-rays and light charged pArticles) Barrel segment consisting of 128 CsI(Tl) crystals and readout photodetectors. In this work, we present the individual crystal response to photons from inelastic and radiative capture reactions of protons on \(^{27}\)Al, as well as a preliminary analysis of the calorimetric response of the prototype, with special focus on the energy resolution of the calorimeter.