Design, construction and commissioning of a technological prototype of a highly granular SiPM-on-tile scintillator-steel hadronic calorimeter

International audienceThe CALICE collaboration is developing highly granularelectromagnetic and hadronic calorimeters for detectors at futureenergy frontier electron-positron colliders. After successful testsof a physics prototype, a technological prototype of the AnalogHadron Calorimeter has been built, based on a design andconstruction techniques scalable to a collider detector. Theprototype consists of a steel absorber structure and active layersof small scintillator tiles that are individually read out bydirectly coupled SiPMs. Each layer has an active area of72 × 72 cm^2 and a tile size of3 × 3 cm^2. With 38 active layers, the prototypehas nearly 22,000 readout channels, and its total thicknessamounts to 4.4 nuclear interaction lengths. The dedicated readoutelectronics provide time stamping of each hit with an expectedresolution of about 1 ns. The prototype was constructed in2017 and commissioned in beam tests at DESY. It recorded muons,hadron showers and electron showers at different energies in testbeams at CERN in 2018. In this paper, the design of the prototype,its construction and commissioning are described. The methods usedto calibrate the detector are detailed, and the performance achievedin terms of uniformity and stability is presented