Researchers at Fermilab?a particle physics laboratory outside Chicago?were the recent recipients of this serendipity. A giant doughnut-shaped electromagnet that has been collecting dust for the past 12 years at Brookhaven National Laboratory in New York could be the vital centerpiece of an upcoming experiment, one that could help scientists understand data coming out of the Large Hadron Collider in Europe. This Saturday, scientists and engineers on both ends are going to move it. But the 50-ft. magnet is so fragile that even the slightest bend?a twist or sag a third of an inch anywhere?could irreparably damage it.
"It's one of a kind," says Chris Polly, the project manager of Muon g-2, the experiment that needs the magnet. He plans for Muon g-2 to be up and running by 2016. But if the magnet breaks, "it would cost a lot more money and cause a pretty hefty delay."
Losing the magnet would be devastating for more than just fiscal reasons. As the Large Hadron Collider at CERN in Switzerland prepares to bump up the power for its upcoming experiments, Fermilab's new project, Muon g-2, could play a supporting role. "This is a rapid timescale we're talking about," Polly says. "We want to know the physics right now because it's helpful in interpreting data coming from the Large Hadron Collider."
The Big Move
For someone in charge of $25 million worth of absurdly delicate equipment, Del Allspach, the engineer in charge of the move, describes the journey with surprising calm. Because the magnet can't be disassembled without damaging it, Fermilab is going to ship the thing to Illinois on a white-knuckle waterway journey down the Atlantic and up the Mississippi River. The lab has paid for a private barge, a nearly unbendable casing, and a hydraulically leveling trailer designed just for this mission to transport the magnet to and from the water.
On the monthlong boat ride, the magnet will be locked down in its casing, covered from the elements, and decked out with safety-measuring equipment. "We have four accelerometers and one tiltmeter," says Allspach. "We will be watching the readouts of those in real time." If any of his equipment hints that the water is getting too choppy, it'll feed to a satellite modem, and he'll be autodialed day or night. (You can follow the magnet's path on the Muon website.)
On the boat, the magnet will be able to withstand breakers larger than 16 feet. Still, a surprise jolt or an unexpectedly large storm could turn the prize magnet into a 17-ton paperweight. Allspach is assured that with weather forecasting and the protective and monitoring equipment, the magnet?and with it the hopes of starting the Muon g-2 experiment as soon as possible?is in no danger. "We've done calculations," he says, "and we'll have complete control of the barge."
Combing the Vacuum
Muon g-2 will survey the short-lived particles that pop in and out of existence in a vacuum. The experiment relies on one of the strange truths in particle physics: that empty space is anything but empty. Even in a perfect vacuum pairs of particles?a proton and antiproton, for example, or an electron and antielectron?materialize from the void, only to disappear back into oblivion an instant later. "So a vacuum is mainly nothing," says Bill Morse, a particle physicist with the Muon g-2 experiment.
The scientists at Fermilab plan to study these fleeting particles by shooting volleys of muons (the fat, short-lived cousin of the electron) through the giant, empty electromagnet. The electromagnet causes the muons to wobble like toy tops losing their balance. For nearly a century, scientists have been calculating how much the muons are supposed to wobble, but in reality they wobble a tiny bit more than predicted. This is because the muons are pushing past the other particles popping in and out of the vacuum, each of which can steal a little bit of energy. Physicists call this gap between expectation and reality g-2, hence the experiment's name.
This figure, g-2 is more than just an interesting Snapple-cap fact. "It provides the way to see if new theories actually fit our observations," says Glen Marshall, a particle physicist at Canada's national particle physics laboratory, who is not involved in the Muon g-2 experiment. Any theory that seeks to explain the crazy world of subatomic particles must predict the value of g-2. Any theory that can't, or gets the number wrong, is dead in the water.
Fermilab's experiment will be the most accurate g-2 measurement yet, and accuracy is everything. As the measurements of g-2 become more precise, physicists can narrow down what matter does or doesn't exist in the universe. And the last time g-2 was measured, the theory that almost perished was a big one.
The Hint of Something More
The Standard Model of particle physics not only lays out what particles exist and how they interact, but it also explains a huge variety of subatomic phenomenon that other theories can't. Earlier this year, the theory had its biggest open question answered when scientists at the Large Hadron Collider discovered the Higgs boson.
Like all particle physics theories, the Standard Model specifies a precise number for g-2. But the last time g-2 was measured?at Brookhaven in the 1990s using the very same electromagnet Fermilab is moving?scientists discovered that the Standard Model didn't match their findings.
This could have been a major blow to the Standard Model, but there was a slim possibility?just 0.3 percent?that the Brookhaven findings were false and due to chance. And in particle physics, that's too much. For something to be considered a true discovery, the possibility has to be whittled down to (an arbitrary but widely accepted) 0.00006 percent. Brookhaven lacked the power to make a more accurate measurement, and so the electromagnet and the researchers who ran the experiment have been waiting more than a decade to give it another try.
At Fermilab, physicists will get their second chance. Because of advancements made in the past 10 years, and because Fermilab will be recycling parts from the Tevatron (the high energy particle accelerator that was shut down in 2011), researchers will be able to record 20 times more muons than they could at Brookhaven. Because of this the Muon g-2 experiment will be able to put the Standard Model to the test, and perhaps see whether there is something strange left to be discovered. "It could be that there's a new force" or new particles, Morse says. "Another theory is dark light. All of these are possibilities. We don't know."
But Marshall stresses that the Muon g-2 experiment is only one part of a much bigger picture. "You can't find out what's beyond the Standard Model with just g-2," he says. Regardless, whether the Muon g-2 experiment challenges the Standard Model, the measurement will help make sense of any future results coming from other laboratories. "If there is a new particle discovered at CERN," Marshall says, "we'll know something about it right away because of the g-2 experiment."
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