A segmented scintillator-lead photon calorimeter using a double wavelength shifter optical readout system

The construction and performance of a prototype scintillator lead photon calorimeter using a double wavelength shifter optical readout is described. The calorimeter is divided into 4 individual cells, each consisting of 44 layers of 3 mm lead plus 1 cm thick scintillator. The edges of each scintillator plate are covered by acrylic bars doped with a wavelength shifting material. The light produced in each scintillator plate is first converted in these bars and then converted a second time in a set of acrylic rods, which run longitudinally through the calorimeter along the corners of each calorimeter cell. A photomultiplier is attached to each of these rods at the back end of the calorimeter. The energy resolution obtained with incident electrons in the energy range of 2–30 GeV is σ/E = 0.12/√E. The uniformity of response across the front face of each cell was measured. Showers within each cell can be localised with an accuracy of better than σ = 7 mm.