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Special Seminar | High Energy Physics Division

Breaking the Standard Model: The Muon g-2 Experiment at Fermilab

HEP Special Seminar

Abstract: A new measurement of the anomalous magnetic moment of the muon, aµ ≡ (g − 2)/2, is being performed at Fermi National Accelerator Laboratory with data taking under way in 2018. The most recent measurement, performed at Brookhaven National Laboratory and completed in 2001, shows a 3.7 standard deviation discrepancy with the Standard Model value of aµ. The new measurement will accumulate 21 times those statistics by using upgraded magnet, detector, and storage ring systems, enabling a measurement of aµ to 140 ppb, a factor of 4 improvement in the uncertainty the previous measurement.

This improvement in precision, combined with recent improvements in our understanding of the QCD contributions to the muon anomalous moment, could provide a discrepancy from the Standard Model of more than 7σ, a clear indication of new physics.The measurement of aµ requires precise measurements of the magnetic field and the anomalous precession frequency ωa with systematic uncertainties on each of better than 70 ppb.

This talk will focus on the measurement of ωa, which is extracted from the time spectra of positron decays as recorded by 24 electromagnetic calorimeters. The detectors and electronics as well as the data acquisition, processing, and analysis will be presented. Special attention will be given to the Q-method, a novel analysis technique that integrates the detector current as a proxy for event energy. The first production run is nearing completion, and the current status of the measurement will be shown.