Scintillator tile hadron calorimeter with novel SiPM readout

The CALICE collaboration is presently constructing a test hadron calorimeter (HCAL) with 7620 scintillator tiles readout by novel photo-detectors—Silicon Photomultipliers (SiPMs). This prototype is the first device which uses SiPMs on a large scale. We present the design of the HCAL and report on measured properties of more than 10 000 SiPMs. We discuss the SiPM efficiency, gain, cross-talk, and noise rate dependence on bias voltage and temperature, including the spread in these parameters. We analyze the reasons for SiPM rejection and present the results of the long-term stability studies. The first measurements of the SiPM radiation hardness are presented. We compare properties of SiPM with the properties of similar devices, MRS APD and MPPC. A possibility to make the tiles thinner and to read them out without WLS fibers has been studied.