Physicists Take Particle Accelerator On 5,000-Kilometer Trip To Understand The Nature Of Muons

The Muon g-2 electromagnet at Fermilab. Fermilab

Muons are the heavier cousins of the electrons, having a lot of the same properties while being 207 times heavier. It should also behave in the same way, but an experiment at Brookhaven National Laboratory has shown that there’s something wrong with the muon and it could be physics beyond our current understanding.

To learn more, physicists needed a more intense muon beam, like the one at Fermilab in Chicago, but instead of building a new particle accelerator, which would have cost 10 times more, researchers moved the Brookhaven one to Chicago. The 5,000-kilometer (3,200-mile) move started in Long Island, New York, went down to Florida, then on a barge through the Tennessee-Tombigbee riverways and Illinois River, until it was then driven into Fermilab.

The sophisticated superconducting ring arrived in Chicago in the summer of 2013, and since then, physicists have been busy kitting it out for the big experiment, making sure everything is in top shape.

"Getting the magnet here was only half the battle," Chris Polly, project manager of the Muon g-2 experiment, said in a statement. "Since it arrived, the team here at Fermilab has been working around the clock installing detectors, building a control room and, for the past year, adjusting the uniformity of the magnetic field, which must be precisely known to an unprecedented level to obtain any new physics. It's been a lot of work, but we're ready now to really get started."

The goal for the particle accelerator is to measure precisely the anomalous magnetic dipole moment of the muon, pretty much how a muon wobbles due to quantum effects after being in a magnetic field. The measured value is 3.4 standard deviations from the theoretical value, which suggests there’s only a small chance (3 in 10,000) that the experimental data was a fluke.

The Muon g-2 electromagnet during the last leg of its trip. Fermilab

The new experiment, called Muon g-2, was started on May 31, 2017, and will run for at least three years. Physicists expect to improve the measurement by at least four times.

"The Muon g-2 experiment's first beam truly signals the start of an important new research program at Fermilab, one that uses muon particles to look for rare and fascinating anomalies in nature," said Fermilab Director Nigel Lockyer. "After years of preparation, I'm excited to see this experiment begin its search in earnest."

The first results will come out later this year and will hopefully shine a light on the mystery that lies beyond the current theoretical model.


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