Muon magnet's moment has arrived

Andre Salles for Fermilab

Kevin Pitts, a professor of physics and an associate dean of engineering at the University of Illinois at Urbana Champaign, leads the U. of I. effort on the Muon g-2 experiment at Fermilab.
Kevin Pitts, a professor of physics and an associate dean of engineering at the University of Illinois at Urbana Champaign, leads the U. of I. effort on the Muon g-2 experiment at Fermilab.
What do you get when you revive a beautiful 20-year-old physics machine, carefully transport it 3,200 miles over land and sea to its new home, and then use it to probe strange happenings in a magnetic field? Hopefully you get new insights into the elementary particles that make up everything.

The Muon g-2 experiment, located at the U.S. Department of Energy’s (DOE) Fermi National Accelerator Laboratory, has begun its quest for those insights. This month, the 50-foot-wide superconducting electromagnet at the center of the experiment saw its first beam of muon particles from Fermilab’s accelerators, kicking off a three-year effort to measure just what happens to those particles when placed in a stunningly precise magnetic field. The answer could rewrite scientists’ picture of the universe and how it works. Researchers at the University of Illinois at Urbana-Champaign are among the members of the Muon g-2 collaboration, comprising  in all more than 150 scientists and engineers from more than 30 institutions in nine countries.

“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,” comments Fermilab Director Nigel Lockyer. “After years of preparation, I’m excited to see this experiment begin its search in earnest.”

Getting to this point was a long road for Muon g-2, both figuratively and literally. The first generation of this experiment took place at the U.S. DOE’s Brookhaven National Laboratory in New York State in the late 1990s and early 2000s. The goal of the experiment was to precisely measure one property of the muon – the particles’ precession, or wobble, in a magnetic field. The final results were surprising, hinting at the presence of previously unknown phantom particles or forces affecting the muon’s properties.

The ring, having been transported from Brookhaven National Laboratory in Long Island, NY, arrives at Fermilab. Image courtesy of Fermilab.
The ring, having been transported from Brookhaven National Laboratory in Long Island, NY, arrives at Fermilab. Image courtesy of Fermilab.
The new experiment at Fermilab will make use of the laboratory’s intense beam of muons to definitively answer the questions the Brookhaven experiment raised. And since it would have cost 10 times more to build a completely new machine at Brookhaven rather than move the magnet to Fermilab, the Muon g-2 team transported that large, fragile superconducting magnet in one piece from Long Island to the suburbs of Chicago in the summer of 2013.

The magnet took a barge south around Florida, up the Tennessee-Tombigbee waterway and the Illinois River, and was then driven on a specially designed truck over three nights to Fermilab. And thanks to a GPS-powered map online, it collected thousands of fans over its journey, making it one of the most well-known electromagnets in the world.

“Getting the magnet here was only half the battle,” adds Chris Polly, project manager of the Muon g-2 experiment. “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 installed Muon g-2 ring with instrumentation, at Fermi National Laboratory outside Batavia, IL, in the greater Chicago area. Image courtesy of Fermilab.
The installed Muon g-2 ring with instrumentation, at Fermi National Laboratory outside Batavia, IL, in the greater Chicago area. Image courtesy of Fermilab.
That work has included the creation of a new beamline to deliver a pure beam of muons to the ring, the installation of a host of instrumentation to measure both the magnetic field and the muons as they circulate within it, and a year-long process of “shimming” the magnet, inserting tiny pieces of metal by hand to shape the magnetic field. The field created by the magnet is now three times more uniform than the one it created at Brookhaven.

U. of I. scientists have played a major role in constructing the experiment, including a high precision timing system that will be used as the “heartbeat” of the experiment. The U. of I. team has also been involved in detector construction, the data acquisition system, and preparation for data-taking.  Illinois team members include postdoctoral researchers Sabato Leo and Sudeshna Ganguly, graduate students Cristina Schlesier and Adithya Kuchibhotla, and several undergraduate students collaborating with Professors of Physics Kevin Pitts and Paul Debevec. 

“It has been amazing to see this experiment go from a concept to reality, and now comes the data that we will analyze,” shares Ganguly.

Over the next few weeks the Muon g-2 team will test the equipment installed around the magnet, which will be storing and measuring muons for the first time in 16 years. Later this year, they will start taking science-quality data, and if their results confirm the anomaly first seen at Brookhaven, it will mean that the elegant picture of the universe that scientists have been working on for decades is incomplete, and that new particles or forces may be out there, waiting to be discovered.

“This is an exciting milestone.  We have worked for many years to get to this point, but there is much more to do,”  Pitts comments.  “We are excited to find out what nature tells us.  But to get to that answer will take several more years of hard work.”

Learn more about the Muon g-2 experiment here: Take a 360-degree tour of the Muon g-2 experiment hall here:

The Muon g-2 experiment is supported by DOE’s Office of Science and the National Science Foundation.

Fermilab is America’s premier national laboratory for particle physics research. A U.S. Department of Energy Office of Science laboratory, Fermilab is located near Chicago, Illinois, and operated under contract by the Fermi Research Alliance LLC. Visit Fermilab’s website at and follow us on Twitter @Fermilab.

The DOE Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit

Recent News

  • Looking back
  • Astrophysics
  • Astrophysics/Cosmology
  • Astronomy
  • Numerical Relativity

Today’s historic joint announcement by the U.S.-based Laser Interferometer Gravitational-Wave Observatory (LIGO) and the Europe-based Virgo detector of the first detection of gravitational waves produced by colliding neutron stars is doubly noteworthy. It’s also the first cosmic event observed in both gravitational waves and light—some 70 ground- and space-based observatories observed the colliding neutron stars. This is arguably the biggest moment to date in “multi-messenger astronomy.”

In a press release issued by LIGO and Virgo collaborations, National Science Foundation Director France A. Córdova comments, “It is tremendously exciting to experience a rare event that transforms our understanding of the workings of the universe. This discovery realizes a long-standing goal many of us have had, that is, to simultaneously observe rare cosmic events using both traditional as well as gravitational-wave observatories. Only through NSF’s four-decade investment in gravitational-wave observatories, coupled with telescopes that observe from radio to gamma-ray wavelengths, are we able to expand our opportunities to detect new cosmic phenomena and piece together a fresh narrative of the physics of stars in their death throes.”

Well before the development of today’s innovative technologies supporting this simultaneous gravitational-wave and optical observation, early research in numerical relativity at the University of Illinois at Urbana-Champaign helped to lay the theoretical foundation for it. In fact, many features of the discovery had been predicted in the early computational simulations of Professor of Physics and Astronomy Stuart Shapiro and his group.

  • Research
  • Astrophysics
  • Astrophysics/Cosmology

A team of scientists using the Dark Energy Camera (DECam), the primary observing tool of the Dark Energy Survey (DES), was among the first to observe the fiery aftermath of a recently detected burst of gravitational waves, recording images of the first confirmed explosion from two colliding neutron stars ever seen by astronomers.

Scientists on the DES joined forces with a team of astronomers based at the Harvard-Smithsonian Center for Astrophysics (CfA) for this effort, working with observatories around the world to bolster the original data from DECam. Images taken with DECam captured the flaring-up and fading over time of a kilonova – an explosion similar to a supernova, but on a smaller scale – that occurs when collapsed stars (called neutron stars) crash into each other, creating heavy radioactive elements.

Two scientists at the University of Illinois at Urbana-Champaign are members of the DES collaboration, Professors Joaquin Vieira of the Departments of Astronomy and of Physics and Felipe Menanteau of the Department

  • New Research Center
  • Condensed Matter Physics
  • Materials Research

Innovative materials are the foundation of countless breakthrough technologies, and the Illinois Materials Research Science and Engineering Center will develop them. The new center is supported by a six-year, $15.6 million award from the National Science Foundation’s Materials Research Science and Engineering Centers program. It is led by Professor Nadya Mason of Engineering at Illinois’ Department of Physics and its Frederick Seitz Materials Research Laboratory

By building highly interdisciplinary teams of researchers and students, the Illinois Materials Research Center will focus on two types of materials. One group will study new magnetic materials, where ultra-fast magnetic variations could form the basis of smaller, more robust magnetic memory storage. The second group will design materials that can withstand bending and crumpling that typically destroys the properties of those materials and even create materials where crumpling enhances performance.

  • In the Media
  • Condensed Matter Physics
  • Biological Physics

Quanta Magazine recently spoke with Goldenfeld about collective phenomena, expanding the Modern Synthesis model of evolution, and using quantitative and theoretical tools from physics to gain insights into mysteries surrounding early life on Earth and the interactions between cyanobacteria and predatory viruses. A condensed and edited version of that conversation follows.