4/20/2026 Siv Schwink for Illinois Physics
Illinois Physics Professor Paul Debevec has been part of the Illinois g-2 effort since the beginning. He recounts the history of participation from Illinois.
Written by Siv Schwink for Illinois Physics
The Breakthrough Prize Foundation announced Sunday, April 19, that it has awarded six $3 million prizes for outstanding discoveries in the sciences and math. The 2026 Breakthrough Prize in Fundamental Physics has been awarded to the Muon g-2 collaborations of CERN, Brookhaven National Laboratory, and Fermilab for their precision measurements of the muon’s anomalous magnetic moment.
Named among the over 300 Breakthrough Prize laureates are numerous Illinois Physics faculty and former faculty members, former postdoctoral researchers, and Ph.D. alumni who contributed to the experiments during their time at Illinois.
For over sixty years, scientists and engineers have continuously pushed the experimental precision of muon g-2 science in pursuit of a single, significant number: the anomalous magnetic moment of the muon. The muon is an unstable cousin of the electron, weighing in at about 200 times the electron’s mass—and like the electron, it can behave like a tiny magnet. Subjected to a magnetic field, the muon’s magnetic moment causes the particle to precess. Measuring the muon’s magnetism through this Precession and comparing it to theoretical predictions allows physicists to test whether any unknown particles or forces are affecting the muon’s magnetic strength, serving as a probe for new physics beyond the standard model of particle physics.
Illinois Physics Professor Paul Debevec has been part of the Illinois g-2 effort since the beginning. He said, “There is not only one path to achieve a breakthrough. This prize recognizes a path that involved three generations of engineers and scientists, working at three major high-energy laboratories, with collaborators from three continents—all to measure one fundamental quantity formed from contributions of all three forces of the quantum world. The precision of this measurement allows an unparalleled confrontation of experiment and theory.”
Illinois experimentalists have contributed to the Brookhaven and Fermilab g-2 experiments from their very beginnings. Debevec recounted the long history of the three experimental efforts.
“The three experiments are called g-2 because they all use muons rotating and precessing in a storage ring,” he said. “CERN originated the storage ring concept. The CERN experiment was completed in 1979, and the final result had a precision of 7.3 parts per million.”
After the CERN effort was complete, Debevec recalls, the U.S. Department of Energy’s Brookhaven National Laboratory organized a workshop in 1984 to discuss the possibility of making a more precise measurement. “To achieve greater precision, the storage ring magnet would be a 15-meter diameter superconducting magnet with a highly uniform field, a magnet which would push the very limits of technology,” he said.
Debevec and University of Washington Professor David Hertzog, then a physics faculty member at Illinois, joined the BNL experiment in 1994. The final result of the BNL experiment was published in 2004, having a precision of 0.54 ppm.
Debevec and Hertzog brought with them to the BNL g-2 experiment postdoctoral researchers Cornelius J. Onderwater, Cenap Ozben, Sergei Sedykh, and David Urner; and Illinois Physics Ph.D. alumni William Deninger, Frederick E. Gray, Timothy D. Jones, Charles Polly, and Michael Sossong—all now Breakthrough Prize laureates. Prior to joining Illinois Physics, Professor Matthias Grosse Perdekamp worked on the BNL g-2 experiment as a Yale postdoctoral researcher—he is also named among the Breakthrough Prize laureates.
Debevec noted, “The Brookhaven experiment was statistics-limited—and it was impractical to pursue higher precision at Brookhaven. Not long after the end of the Brookhaven experiment, a group began to investigate the possibility of continuing the g-2 experiment at Fermilab. The Brookhaven storage ring magnet would be moved to Fermilab, and the group became a formal collaboration.”
From Illinois, faculty members Hertzog, Peter Kammal (now at University of Washington), and Kevin Pitts (now at Virginia Tech) joined the new Fermilab g-2 collaboration.
The final result of the FNAL experiment was published in 2025, having a precision of 0.13 ppm. In June 2025, the Muon g-2 experiment at the U.S. Department of Energy’s Fermilab announced it had achieved the most precise measurement of the magnetic anomaly of the muon, in their third and final result.
In addition to Debevec, Hertzog, Kammal, and Pitts, the Illinois collaborators on the Fermilab g-2 experiment, now named Breakthrough Prize laureates, included former postdoctoral research associates Esra Barlas-Yucel, Sudeshna Ganguly, and Peter Winter, and Ph.D. alumni Jason Crnkovic, Frederick Gray, Brendan Kiburg, Chris Polly, Cristina Schlesier, and Adam Schreckenberger.
It’s worth noting that several Illinois Physics alumni on the Fermilab g-2 experiment went on to hold prominent positions within the experimental effort, including Chris Polly (Fermilab staff scientist, APS Fellow, Mu2e project leader); Peter Winter (current co-spokesperson of the g-2 experiment); and Brendan Kiburg (Wilson Fellow, Fermilab staff scientist, head of the muon department.