Moving a 17-ton magnet from NYC to Chicago makes for material handling marvel
August 2013 - In late July, after more than a month-long journey, a 17-ton magnet arrived at Fermi National Accelerator Laboratory, known as Fermilab, outside Chicago, attracting the awe of scientists and spectators. But this magnet wasn’t delivered by UPS. The 50-foot diameter structure traveled 3,200 miles by barge to Chicago from New York through a carefully orchestrated itinerary involving cranes, wide-load trucks and road closures on either end.
The magnet, officially called the Muon g-2, is a part of a quantum-physics experiment exploring the behavior of short-lived particles called muons within a strong, empty magnetic field. In a supposedly empty vacuum, there are still invisible virtual particles that pop in and out of existence for brief moments, according to Fermilab (brief being about two millionths of a second). With the magnet, scientists can test the presence and interactions of these particles with particle beams traveling in a magnetic field. Fermilab is inheriting the magnet from Brookhaven National Laboratory on eastern Long Island, which used it for a similar experiment in the mid 1990s. Constructing a new magnet would’ve cost about 10 times as much as shipping it.
At the core of the magnet’s assembly are three electromagnetic rings. The largest is 50-foot, 4-inch diameter, the other two rings are 44-foot, 10-inches. For shipping, crews from Emmert International, an Oregon-based rigging company that specializes in heavy-haul transportation, constructed a massive steel fixture to keep the rings stable. The vacuum-sealed coils contain a continuous, seamless length of superconducting wire that couldn’t be cut or broken down to ship. Doing so would’ve compromised the experiment.
“In the end, we decided the easiest way to move the rings was as a unit,” says Del Allspach, project mechanical engineer at Fermilab.
A finely choreographed move, the magnet left Brookhaven National Laboratory for Smith Point Marina on the south shore of Long Island, where a 500-ton-capacity crane loaded the Muon g-2 onto a barge. To keep the magnet assembly from contorting more than 3 millimeters, Emmert shrink wrapped it and outfitted it with a three-point hydraulic leveling system. The fixture and hydraulics kept the rings flat while the shrink wrap guarded the aluminum rings from seawater and the elements.
Then began on water what would’ve been an arduous 900 mile road trip. For weeks, the barge inched along the East Coast between 6 mph and 8 mph, says Allspach. At one point, the barge took safe harbor for five days in the Chesapeake Bay because of high waves off the Virginia coast, and the captain navigated the fine line between rough waters and rocky shores near Cape Hatteras, N.C.
“From there to Mobile, it was great weather,” he says. The barge then entered the Tennessee-Tombigbee Waterway, a manmade system of canals connecting the Tennessee River to the Gulf of Mexico. On July 18, photographers gathered to photograph it passing by the Gateway Arch in St. Louis on the Mississippi River. Nudged up the Chicago Sanitary and Ship Canal by a tugboat named Miss Katie, the Muon g-2 magnet arrived July 20 in Lemont, Ill., at the dock of Ozinga Materials, a concrete company. It made the final 30-mile leg over three nighttime road closures through Chicago’s suburbs atop Emmert’s modular heavy trailer, and pulled by its Prime Mover, moving 5 to 15 mph.
The metal within
To simplify assembly and fabrication when the magnet was built in the 1990s, the its structural body was built in 12 30-degree sections. According to an article in scientific journal Nuclear Instruments and Methods in Physics Research, each section is made from rolled steel plate fabricated by then-Lukens Steel Co. in Coatesville, Pa., the oldest steel mill still in commission, with roots in the early 1800s. Those sections consists of an upper and lower yoke separated by a spacer plate.
The yoke iron is AISI 1006 (0.07 percent carbon content) iron pieces, and the pole pieces from vacuum-cast ultra-low-carbon steel. The three superconducting coils connected together activate the magnet. A 6061-T6 aluminum mandrel houses the conductor, which is a niobium titanium superconductor in a copper matrix with a pure aluminum rectangular stabilizer.
Dark skies threatened storms when the magnet arrived at Fermilab in Batavia, Ill., but that didn’t deter about 3,000 people from attending the magnet’s arrival party on July 26.
“It’s been a very long journey, and it took a lot of work from dozens of people,” said Chris Polly, the project’s manager at Fermilab, in a statement. MM