  An analog hadron calorimeter (AHCAL) prototype of 5.3 nuclear interaction
lengths thickness has been constructed by members of the CALICE Collaboration.
The AHCAL prototype consists of a 38-layer sandwich structure of steel plates
and highly-segmented scintillator tiles that are read out by
wavelength-shifting fibers coupled to SiPMs. The signal is amplified and shaped
with a custom-designed ASIC. A calibration/monitoring system based on LED light
was developed to monitor the SiPM gain and to measure the full SiPM response
curve in order to correct for non-linearity. Ultimately, the physics goals are
the study of hadron shower shapes and testing the concept of particle flow. The
technical goal consists of measuring the performance and reliability of 7608
SiPMs. The AHCAL was commissioned in test beams at DESY and CERN. The entire
prototype was completed in 2007 and recorded hadron showers, electron showers
and muons at different energies and incident angles in test beams at CERN and
Fermilab.
