Breakthrough Prize in Fundamental Physics Awarded to Muon g-2 Collaborations at CERN, Brookhaven National Laboratory, and Fermilab.

This year’s Breakthrough Prize in Fundamental Physics was awarded to three generations of the Muon g-2 experiment: the CERN experiment in the 1970s, the Brookhaven experiment in 2000, and finally the Fermilab experiment, which published its final results in June 2025, helping settle what will remain the most precise measurement of the muon’s magnetic moment for years to come.

The Italian team, consisting of researchers from the INFN Divisions of Naples, Pisa, Rome Tor Vergata, and Trieste, the Frascati National Laboratories, and the CNR-INO in Pisa, has actively participated in the Muon g-2 experiment at Fermilab since its inception. The INFN team contributed significantly to the success of the measurement by designing and building both a complex laser system for absolute calibration of the calorimeters used in the energy measurements, and a high-sensitivity optical magnetometer for measuring magnetic transients.