NIU students, faculty in physics, engineering contribute to Fermilab’s Muon g-2 experiment

A model of the truck that will be used to transport the Muon g-2 ring, placed on a streetscape for scale. (Credit: Fermilab)
A model of the truck that will be used to transport the Muon g-2 ring, placed on a streetscape for scale. (Credit: Fermilab)

Scientists from Northern Illinois University and 25 other institutions worldwide are planning an experiment that could open the doors to new realms of particle physics – and new opportunities for NIU students to participate in leading-edge research.

But first the core of the experiment – a complex electromagnet that spans 50 feet in diameter –must be shipped from the U.S. Department of Energy’s Brookhaven National Laboratory in New York to the DOE’s Fermi National Accelerator Laboratory in west suburban Batavia.

The experiment, called Muon g-2 (pronounced gee-minus-two), aims to study the properties of muons, tiny subatomic particles that exist for only 2.2 millionths of a second.

“Fermilab is leading the world in intensity-frontier experiments, especially with high intensity neutrino and muon beams,” said David Hedin, an NIU Board of Trustees Professor of physics who is involved in the project.

“Scientists believe the study of muons could reveal new processes in nature,” Hedin added. “At NIU, Muon g-2 is already providing great opportunities for our undergraduates and graduate students to be involved in a high-profile, high-priority experiment that ultimately will help us better understand the building blocks of nature.”

David Hedin
David Hedin

Physics professors Michael Fortner and Michael Eads, along with mechanical engineering professor Nicholas Pohlman, are also involved in Muon G-2 – along with about eight undergraduates and graduate students.

“Most of us are working on sub-detectors for the project,” Eads said. “Nick and some engineering students have been working on the design of various components. The physics folks are trying to figure out the assembly process and design testing procedures to be used during the assembly.”

The core of the experiment is a machine built at Brookhaven in the 1990s, and the centerpiece of that machine is a circular electromagnet, 50 feet wide. It’s made of steel and aluminum, with superconducting cable inside.

“It costs about 10 times less to move the magnet from Brookhaven to Illinois than it would to build a new one,” said Lee Roberts of Boston University, spokesperson for the Muon g-2 experiment. “So that’s what we’re going to do. It’s an enormous effort from all sides, but it will be worth it.”

While most of the machine can be disassembled and brought to Fermilab in trucks, the massive electromagnet must be transported in one piece. It also cannot tilt or twist more than a few degrees, or the complex wiring inside will be irreparably damaged.

The Muon g-2 team has devised a plan to make the 3,200-mile journey that involves loading the ring onto a specially prepared barge and bringing it down the East Coast, around the tip of Florida and up the Mississippi River to Illinois. The ring is expected to leave New York in early June, and land in Illinois in late July. (See related video animation and more images.)

Physicists stand inside the Muon g-2 storage ring, in its current location at Brookhaven National Laboratory in New York. (Credit: Brookhaven National Laboratory)
Physicists stand inside the Muon g-2 storage ring, in its current location at Brookhaven National Laboratory in New York. (Credit: Brookhaven National Laboratory)

Once it arrives, the ring will be placed onto a truck built just for this purpose, and driven to Fermilab. The land transport portions on both the New York and Illinois ends of the trip will occur at night – to minimize traffic delays – and the truck will only travel, at most, 10 miles per hour. The complete trip from the Illinois port to Fermilab should take two consecutive nights.

“The transport of the ring from Brookhaven to Fermilab is a great example of the cooperation that exists between national laboratories,” said James Siegrist, associate director of science for high-energy physics with the U.S. Department of Energy. “The Muon g-2 experiment is an important component of the future of particle physics in the United States.”

Once at Fermilab, the storage ring will be used to hold muons created in the laboratory’s accelerators. Muons “wobble” when placed in a magnetic field, and based on what we know about the universe, scientists have predicted the exact value of that wobble. An experiment using the same machine at Brookhaven in the 1990s saw evidence for – though not definitive proof of – a departure from that expected value.

“Brookhaven found this tantalizing discrepancy, and if it’s really a departure from the expected value, then there must be some new physics that we don’t yet understand and need to figure out,” NIU’s Eads said. “It was recognized that Fermilab is best equipped to conduct further g-2 experiments, because the laboratory can make more muons than Brookhaven, and in a sense, better muons.

“This will be the first experiment in a new age for Fermilab, and it’s exciting for us to be part of it,” Eads added. “NIU has a long tradition of collaboration with Fermilab, and this is the natural next step. It’s important to our faculty members and especially to our students. To give them an opportunity to participate in an experiment of this magnitude is one we can’t pass up.”

The experiment is scheduled to begin taking data in 2016.

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