Use of micro-pixel avalanche photodiodes for the readout of a lead/scintillator hadron calorimeter

The application of micro-pixel Avalanche photodiodes (MAPD) for the readout of hadron calorimeters is discussed. A prototype calorimeter was constructed consisting of individual lead/scintillator sandwich modules with a sampling satisfying the compensating condition. The light from each scintillator tile is captured and transported with WLS fibers embedded in the scintillator and extended to the rear end of the module. A set of 6 WLS fibers from neighboring tiles is grouped in one bundle and viewed by a 3x3 mm2 avalanche micro-pixel photodiode. The design provides a longitudinal segmentation of the module into 10 sections with independent MAPD readout. Use of MAPDs with pixel density 104/mm2 ensures good linearity of calorimeter response over a wide dynamical range. The performance of the calorimeter prototype in beam tests is reported.