The calorimeter (BGO) is made up of 14 layers of BGO bars in a hodoscopic arrangement. Each BGO bar is 2.5 cm by 2.5 cm in cross section and 60 cm in length, making it the longest BGO crystals ever produced. The bars are readout at both ends with PMTs, each PMT is readout from 3 dynodes (2, 5, 8) to extend the dynamic range. The total thickness of the calorimeter is equivalent to 31 radiation lengths and 1.6 interaction lengths. An excellent electromagnetic energy resolution of 1.5% above 100 GeV, and a very good hadronic energy resolution of better than 40% above 800 GeV can be expected.