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Precision Magnetic Field Measurement System for the New Muon g-2 Experiment

Ran Hong, Argonne National Laboratory
Monday, June 19, 2017 - 2:30pm to 3:30pm
CENPA Conference Room, Rm 178

​The New Muon g-2 Experiment (E989) at Fermilab is aiming at measuring the anomalous magnetic moment of muon a with a precision of 140 ppb. This new experiment is expected to resolve the long-standing 3.5 standard deviation between the previous muon g-2 measurement (E821) at Brookhaven National Laboratory and the Standard Model calculation, and potentially discover new physics. In E989, both the muon precession frequency and the magnetic eld experienced by the muons will be measured. The magnetic eld in the muon storage region is scanned by 17 nuclear- magnetic resonance (NMR) probes carried by a trolley, and the eld in between trolley scans is monitored by 384 fixed NMR probes outside the muon storage region. E898 requires a determination of the magnetic eld with an accuracy better than 70 ppb. To achieve this goal, the magnetic field is shimmed to a higher uniformity than that in E821. The trolley system and the fixed probe system from E821 were refurbished and upgraded with new electronics, probes and modern control systems. A new absolute calibration probe system is being built to reach the desired accuracy. A test solenoid magnet was set up at Argonne National Laboratory for calibrating the NMR probes and the precision studies of systematic uncertainties. In this presentation, we will describe the upgrades for the trolley and xed probe systems, new features of the absolute calibration system, the data acquisition system and recent installation and calibration progresses.

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