Enter Fermilab, where a new campus devoted to studying muons was being built.
“That opened up a world of possibility,” Dr. Polly recalled in his biographical article. By this time, Dr. Polly was working at Fermilab; he and his colleagues could redo the g-2 experiment there, with more precision. He became the project manager for the experiment.
To conduct the experiment, however, they needed the 50-foot magnet racetrack from Brookhaven. And so in 2013, the magnet went on a 3,200-mile odyssey, mostly by barge, down the Eastern Seaboard, around Florida and up the Mississippi River, then by truck across Illinois to Batavia, home of Fermilab.
The magnet resembled a flying saucer, and it drew attention as it was driven south across Long Island at 10 miles per hour. “I walked along and talked to people about the science we were doing,” Dr. Polly wrote. “Moving it through the Chicago suburbs to Fermilab offered another chance for outreach. It stayed over one night in a Costco parking lot. Well over a thousand people came out to see it and hear about the science.”
The experiment started up in 2018 with a more intense muon beam and the goal of compiling 20 times as much data as the Brookhaven version.
Meanwhile, in 2020, a group of 170 experts known as the Muon g-2 Theory Initiative published a new consensus value of the theoretical value of muon’s magnetic moment, based on three years of workshops and calculations using the Standard Model. That answer reinforced the original discrepancy reported by Brookhaven.
Reached by phone on Monday, Aida X. El-Khadra, a physicist at the University of Illinois and a co-chair of the Muon g-2 Theory Initiative, said they had been waiting for this result for a long time.
“I have not had the feeling of sitting on hot coals before,” she said.
On the day of the Fermilab announcement another group, using a different technique known as a lattice calculation to compute the muon’s magnetic moment, got a different answer than Dr. El-Khadra’s group.