ELECTROMAGNETIC CALORIMETER WITH THIN GAP WIRE CHAMBERS

In this paper we report about the experimental results obtained in a b eam test of a gas sampling EM calorimeter. The module consists of 20 t hin gap (30 mm) multiwire chambers as active elements, interleaved wit h brass absorber plates of 12 mm thickness or 0.84 radiation length. T he KEK electron beam was tuned to energies of 0.5, 1.0, 2.0, 3.0, 4.0 GeV. The construction and performances of the chamber, the assembling of the module, the experimental setup and data acquisition system are briefly described. The energy resolution of the module is found to be 25%/root E (E in GeV). In the range of measured energies, good lineari ty of the energy response is obtained. The longitudinal development of EM shower, the relation between energy resolution and thickness of th e absorber as well as the high voltage of the chamber are studied. The effect of incident position of the beam on the performance of the mod ule is also given.