Speaker
Description
The Muon g-2 Experiment (E989) at Fermilab measures the anomalous magnetic moment of the muon $a_{\mu}$, aiming at resolving the 3.6-$\sigma$ discrepancy between the previous measurement and the Standard Model calculation with a improved precision of 140 part-per-billion (ppb). In E989, the muon beam is stored in a ring magnet. The spin precession frequency $\omega_{a}$ is measured by counting the decay positrons in 24 calorimeters, and the magnetic field is measured by nuclear magnet resonance (NMR) probes. An in-vacuum field scanning system consisting of NMR probes and read-out electronics was implemented to measure the magnetic field applied to the muon beam. An additional 378 NMR probes placed at fixed locations outside the vacuum chamber monitor the field drift in between scans. Another high-accuracy probe was designed for calibrating the probes in the scanner. In this presentation, the magnetic field measurement hardware system and analysis methods will be described in detail. The progress of the Run-1 data analysis and improvements in Run-2 will also be presented.
