Magnetic-field measurement and analysis for the Muon g-2 Experiment at Fermilab

The Fermi National Accelerator Laboratory (FNAL) Muon g - 2 Experiment has measured the anomalous precession frequency a(mu) = (g(mu) - 2)/2 of the muon to a combined precision of 0.46 parts per million with data collected during its first physics run in 2018. This paper documents the measurement of the magnetic field in the muon storage ring. The magnetic field is monitored by systems and calibrated in terms of the equivalent proton spin precession frequency in a spherical water sample at 34.7 degrees C. The measured field is weighted by the muon distribution resulting in (omega) over tilde (p)', the denominator in the ratio omega(a)/(omega) over tilde (p)' that together with known fundamental constants yields a(mu). The reported uncertainty on (omega) over tilde'(p) for the Run-1 data set is 114 ppb consisting of uncertainty contributions from frequency extraction, calibration, mapping, tracking, and averaging of 56 ppb, and contributions from fast transient fields of 99 ppb.

Automated summary

The FNAL Muon g-2 Experiment has measured the anomalous precession frequency of the muon to a high precision, documenting the measurement of the magnetic field in the muon storage ring. The data collected during the first physics run in 2018 provides important insights for future research.