Longitudinally segmented lead/scintillator hadron calorimeter with micro-pixel APD readout

The construction and performance of a modular hadron calorimeter prototype is described. The prototype consists of 9 individual lead/scintillator sandwich modules with the sampling satisfying the compensating condition. The light from the individual scintillator tiles is captured and transported with the WLS-fibers embedded in the scintillator and extended along the lateral side to the rear end of the module. Set of 6 WLS-fibers from the neighboring tiles is grouped in one bundle and viewed by a 3×3 mm2 avalanche micro-pixel photodiode. The construction ensures a longitudinal segmentation of the module in 10 independent sections. The results of beam tests of the calorimeter prototype are presented. The energy resolution σ / E ≈ 53 % / E ( GeV ) was obtained.