Performance of the Muon g−2 calorimeter and readout systems measured with test beam data

A single calorimeter station for the Muon g−2 experiment at Fermilab includes the following subsystems: a 54-element array of PbF2 Cherenkov crystals read out by large-area SiPMs, bias and slow-control electronics, a suite of 800MSPS waveform digitizers, a clock and control distribution network, a gain calibration and monitoring system, and a GPU-based front-end which is read out through a MIDAS data acquisition environment. The entire system performance was evaluated using 2.5–5GeV electrons at the End Station Test Beam at SLAC. This paper includes a description of the individual subsystems and the results of measurements of the energy response and resolution, energy-scale stability, timing resolution, and spatial uniformity. All measured performances meet or exceed the g−2 experimental requirements. Based on the success of the tests, the complete production of the required 24 calorimeter stations has been made and installation into the main experiment is complete. Furthermore, the calorimeter response measurements reported here informed the design of the reconstruction algorithms that are now employed in the running g−2 experiment.