BEAM TESTS OF THE ZEUS BARREL CALORIMETER

A fully compensating uranium-scintillator calorimeter was constructed for the ZEUS detector at HERA. Several of the barrel calorimeter modul es were subjected to beam tests at Fermilab before shipping them to DE SY for installation. The calibrations of the modules used beams of ele ctrons and hadrons, measuring the uniformity of the response, and chec king the resolution. The runs also provided opportunity to test a larg e fraction of the actual ZEUS calorimeter readout system in an integra ted beam environment more than one year before HERA turn on. The exper iment utilized two computer controlled mechanical structures. one of w hich was capable of holding up to four modules in order to study showe r containment, and a magnetic spectrometer with a high resolution beam tracking system. During two running periods, beams of 6 to 110 GeV co ntaining e, mu, pi, and pBAR were used. The results show energy resolu tions of 35%/square-root E for hadrons and 19%/square-root E for elect rons, uniformities at the 1% level, energy nonlinearity less than 1%, and equal response for electrons and hadrons.