the zeus calorimeter was a uranium scintillator based sampling calorimeter and divided into 3 main sections: the bcal (barrel calorimeter), fcal (forward calorimeter), and rcal (rear calorimeter). each section was subdivided transversely into towers, and longitudinally into emc (electro-magnetic calorimeter) or hac (hadronic calorimeter). the smallest subdivision in the calorimeter was called a cell. each cell was read-out by two photomultiplier tubes (pmt), which helped ensure that there were no holes in the coverage if one of the two pmts failed.