The tracker systems for the muon ionization cooling experiment

The Muon Ionization Cooling Experiment (MICE) will be the first experiment to demonstrate muon ionization cooling in the momentum range of 140–240 MeV/c. The experiment is a single-particle experiment where the input and output beam emittances are constructed from an ensemble of selected single-muon candidates. The fiber trackers are placed in a solenoidal field of 4 T (one before and one after the cooling channel) to measure the muon 4-momentum and provide the basic information for determining the emittances. This paper gives a brief overview of MICE and then describes the details of the fiber tracker assemblies, the unique construction technique used (which for the first time used 350 μ m diameter scintillating fiber), the readout electronics and performance with respect to light yield, hit resolution and tracking efficiency as measured in a recent cosmic-ray test of the two final tracker systems.