Calibrating Muon Track Reconstruction with a Scattering Target at the Fermilab g-2 Experiment

The muon g-2 experiment at Fermilab is on track to measure the muon magnetic anomaly (a_mu) to a precision of 140 parts per billion. Any significant difference between the theoretical and experimental values of a_mu can indicate beyond the Standard Model physics. Two straw tracker detectors installed in the ring are used to reconstruct the dynamics of the muon beam. Uncertainty in the global alignment of the straw trackers impacts the accuracy of the reconstructed muon beam. During some of the final data-collection runs of the experiment, a target was placed in the ring with the intention of scattering muons into the trackers. Since the alignment of the target can be determined with a greater degree of precision than that of the trackers, the muons scattered off of the target can be used to assess the accuracy of the reconstructed tracks. We use a GEANT4-based simulation program (gm2ringsim) to simulate muon interactions with the target and assess our sensitivity to the tracker's global alignment. Reducing uncertainty in this alignment will help reduce systematic uncertainties in the determination of a_mu.