Johannes Gutenberg University Mainz joins the “Muon g-2 experiment” at Fermilab

New PRISMA+ research group led by Professor Martin Fertl participates at measuring the anomalous magnetic moment of the muon

anomalous magnetic
View into the circular muon storage ring of the "muon g-2 experiment" at Fermilab. photo/©: Martin Fertl, JGU

Professor Martin Fertl and his research group officially join the “Muon g-2 collaboration” at Fermi National Accelerator Laboratory (Fermilab), one of the international partner institutions of Johannes Gutenberg University Mainz (JGU): The collaborations institutional board has unanimously welcomed the new PRISMA+ research group of JGU as an institutional member. This step complements the contributions of JGU to the “Muon g-2 theory initiative” represented by Professor Achim Denig, Professor Harvey Meyer, Professor Marc Vanderhaegen and Professor Hartmut Wittig which aims at refining the theoretical prediction of the value of the anomalous magnetic moment of the muon, paramount to an improved comparison between experiment and theory. Martin Fertl joined Johannes Gutenberg University Mainz and the PRISMA+ Cluster of Excellence on July 1, 2019.

This new tie will further strengthen the partnership between Fermilab and JGU which has also been formalized in a Cooperative research and development agreement (CRADA), in addition to the recent agreement to perform a joint appointment of Fermilab and JGU in the field of neutrino physics.

The standard model on the test bench

The “Muon g-2 collaboration” aims at a determination of the muon anomalous magnetic moment with the unprecedented precision of 140 part per billion. This fourfold improvement over the last experiment, performed at Brookhaven National Laboratory more than 15 years ago, will allow to test the resulting more than 3 standard deviation discrepancy between experiment and the prediction of the Standard Model of Particle Physics in its current form.

At his former position at the Center for Experimental Nuclear Physics and Astrophysics (CENPA) at the University of Washington, Seattle, USA Martin Fertl has also been a member of this collaboration. He led the development of so-called nuclear magnetic resonance probes. These are used to measure the high-precision magnetic field in the circular muon storage ring over the course of the several-years-long science data taking period which was started in 2017. Several hundred of these probes are installed in the walls of the vacuum chambers surrounding the muon storage volume. In addition, a remotely controllable platform carries 17 of the probes around the ring every couple of days to measure the full spatial distribution of the magnetic field. In combination with an additional magnetic field calibration system the magnetic field team aims at the determination of the magnetic field in the muon storage region with an uncertainty of less than 70 parts per billion.