Characterization of large frustum CsI(Tl) crystals for the R3B calorimeter

Studies with different bi-frustum CsI(Tl) crystal samples from several providers, coupled to large area avalanche photodiodes (Hamamatsu S8664-1010 2CH), specifically developed for this project, were performed as part of the R&D program for the design of the R3B calorimeter (CALIFA). Particular attention is given to the energy resolution optimization for CsI(Tl) crystal samples with realistic dimensions. The results obtained with Large Area Avalanche Photo-Diode (LAAPD) are very promising and suggest CsI(Tl) as a suitable candidate for the barrel of the calorimeter.