Abstract

We present details on a new measurement of the muon magnetic anomaly, aμ=(gμ-2)/2. The result is based on positive muon data taken at Fermilab's Muon Campus during the 2019 and 2020 accelerator runs. The measurement uses 3.1 GeV/c polarized muons stored in a 7.1-m-radius storage ring with a 1.45 T uniform magnetic field. The value of aμ is determined from the measured difference between the muon spin precession frequency and its cyclotron frequency. This difference is normalized to the strength of the magnetic field, measured using nuclear magnetic resonance. The ratio is then corrected for small contributions from beam motion, beam dispersion, and transient magnetic fields. We measure aμ=116592057(25)×10-11 (0.21 ppm). This is the world's most precise measurement of this quantity and represents a factor of 2.2 improvement over our previous result based on the 2018 dataset. In combination, the two datasets yield aμ(FNAL)=116592055(24)×10-11 (0.20 ppm). Combining this with the measurements from Brookhaven National Laboratory for both positive and negative muons, the new world average is aμ(exp)=116592059(22)×10-11 (0.19 ppm).

Document Type

Article

Publication Date

2024

Notes/Citation Information

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP 3.

Digital Object Identifier (DOI)

https://doi.org/10.1103/PhysRevD.110.032009

Funding Information

We thank the Fermilab management and staff for their strong support of this experiment, as well as the tremendous support from our university and national laboratory engineers, technicians, and workshops. Greg Bock and Joe Lykken set the blinding clock and diligently monitored its stability. The Muon g − 2 Experiment was performed at the Fermi National Accelerator Laboratory, a U.S. Department of Energy, Office of Science, HEP User Facility. Fermilab is managed by Fermi Research Alliance, LLC (FRA), acting under Contract No. DE-AC02-07CH11359. Additional support for the experiment was provided by the Department of Energy offices of HEP, NP, and ASCR (USA); the National Science Foundation (USA); the Istituto Nazionale di Fisica Nucleare (Italy); the Science and Technology Facilities Council (UK); the Royal Society (UK); the National Natural Science Foundation of China (Grant No. 12211540001, 12075151); MSIP, NRF, and IBS-R017-D1 (Republic of Korea); the German Research Foundation (DFG) through the Cluster of Excellence PRISMAþ (EXC 2118/1, Project ID 39083149); the European Union Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie Grant Agreements No. 101006726, No. 734303; and European Union STRONG 2020 project under Grant Agreement No. 824093 and the Leverhulme Trust, LIP-2021-01.

Download

Share

COinS