Design and assembly of the CsI(Tl) crystal module of the BESⅢ electro-magnetic calorimeter

The CsI(Tl) crystal modules of the Beijing Spectrometer Ⅲ (BESⅢ) electro-magnetic calorimeter (EMC) were designed and assembled through Monte Carlo simulation and experiments. After the assembly was finished, the performance of each crystal module was tested by cosmic rays. All crystal modules were found to work well before the installation of EMC.