SMuK 2021 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 20: Fundamental Symmetries

HK 20.5: Talk

Wednesday, September 1, 2021, 18:15–18:30, H4

Tracking the magnetic field in the Fermilab Muon g–2 storage ring — •René Reimann, Mohammad Ubaidullah Hassan Qureshi, and Martin Fertl for the Muon g-2 collaboration — Institute of Physics and Excellence Cluster PRISMA+, Johannes Gutenberg University Mainz, 55099 Mainz, Germany

Recently the Muon g–2 collaboration published the most precise measurement of the anomalous magnetic moment of the muon, a_µ, with a 460 ppb uncertainty based on the Run 1 data. The measurement principle is based on a clock comparison between the anomalous spin precession frequency of spin-polarized muons, which is the deviation of the Larmor- from the cyclotron-frequency, and a high-precision measurement of the magnetic field environment using nuclear magnetic resonance (NMR) techniques, expressed by the (free) proton spin-precession frequency. To achieve the ultimate goal of a 140 ppb uncertainty on a_µ, the magnetic field in the storage region of the muons needs to be tracked with an uncertainty better then 70 ppb. The magnetic field tracking is composed of three main components, an absolute calibrated NMR probe, a movable array of NMR probes that can be pulled through the storage region of the muons and a set of NMR probes in the vicinity of the storage region. In this talk, we present the measurement and tracking principle of magnetic field and point out improvements for the upcoming analysis of the Run 2 and 3 data.