The CALICE hadron scintillator tile calorimeter prototype

The CALICE Collaboration develops high granularity calorimeters to achieve excellent energy resolution at ILC. One type is a four million channel scintillator tile Hadron Calorimeter (AHCAL) read out with novel photodetectors-Silicon PhotoMultipliers (SiPM). A 1 m3 prototype with 7608 channels was built in order to test the Particle Flow concept and to gain experience with the novel techniques. The prototype and MEPhI/Pulsar SiPMs have demonstrated excellent performance and stability during several months of testing at CERN and FNAL in 2006-2008. Less than 0.08% of SiPMs are broken. The SiPM calibration and monitoring procedures have been developed. Improved SiPMs have been developed by CPTA for the next engineering prototype and their properties are discussed. This prototype will have very slim sensitive planes with electronics inside. It addresses all engineering issues relevant to the real calorimeter at ILC.