UK Physics Team Contributes to Fermilab’s Muon g-2 Experiment, Reveals Evidence of New Physics

LEXINGTON, Ky. (April, 7, 2021) A group of college and college students from the University of Kentucky Department of Physics and Astronomy within the College of Arts and Sciences, supported by the National Science Foundation (NSF), has contributed to a serious experiment on the U.S. Department of Energy’s Fermi National Accelerator Laboratory (Fermilab). The landmark outcomes, announced today, are altering how physicists perceive the subatomic world.

Fermilab’s three-year Muon g-2 experiment revealed that elementary particles, referred to as muons, behave in a means not predicted by the Standard Model of particle physics. The researchers suppose this habits may very well be brought on by the existence of undiscovered particles or forces.

“This new landmark result from the Fermilab Muon g-2 experiment verified a previous tantalizing hint from an experiment at Brookhaven National Laboratory for the need to consider new particles and forces in nature,” stated Renee Fatemi, UK professor of physics and co-principal investigator.

Muons happen naturally when cosmic rays strike Earth’s environment, and particle accelerators at Fermilab can produce them in giant numbers. Like electrons, muons act as if they’ve a tiny inner magnet. In a powerful magnetic discipline, the path of the muon’s magnet precesses, or wobbles, very like the axis of a spinning high or gyroscope. The energy of the interior magnet determines the speed that the muon precesses in an exterior magnetic discipline and is described by a quantity that physicists name the g-factor. This quantity could be calculated with ultra-high precision.

With the assist of a serious gear grant from the NSF, the UK group developed the {hardware} and software program for buying and processing this experimental information.

“The system handles 25 gigabytes-per-second, about 100,000 times the streaming rate of watching Netflix movies,” stated Tim Gorringe, UK professor of physics and co-principal investigator. “The data is then fed to a GPU farm, an array of processing units originally designed for high-performance computer gaming. The GPUs pan the data stream for the telltale ‘chirps’ of electrons ejected in muon decays. These chirps are how we ‘see’ the muon’s wobble and how we measure its g-factor.”

As the muons flow into within the Muon g-2 magnet, additionally they work together with different subatomic particles, known as “quantum foam,” which pop out and in of existence. Interactions with these short-lived particles have an effect on the worth of the g-factor, inflicting the muons’ precession to hurry up or decelerate very barely. The Standard Model predicts this so-called anomalous magnetic second extraordinarily exactly. But if the quantum foam comprises extra forces or particles not accounted for by the Standard Model, that may tweak the muon g-factor additional.

“This quantity we measure reflects the interactions of the muon with everything else in the universe. But when the theorists calculate the same quantity, using all of the known forces and particles in the Standard Model, we don’t get the same answer,” stated Fatemi, who additionally serves as simulations supervisor for the experiment. “This is strong evidence that the muon is sensitive to something that is not in our best theory.”

The outcomes introduced at the moment affirm and construct on an earlier experiment carried out at Brookhaven National Laboratory in 2001. The Fermilab experiment reused the primary element from the Brookhaven experiment, a 50-foot-diameter superconducting magnetic storage ring. The Muon g-2 experiment sends a beam of muons into the storage ring, the place they flow into 1000’s of instances at almost the velocity of sunshine. Detectors lining the ring enable scientists to find out how briskly the muons are precessing.

The UK group was concerned in two simulation efforts to mannequin the storage ring fields and higher perceive their results on the movement of the muons. These simulations are run on state-of-the-art high-performance computing facilities, together with these at Fermilab, the National Energy Research Scientific Computing Center and the Lipscomb Supercomputer Cluster at UK.

UK’s principal investigators embrace Fatemi, Gorringe and Brad Plaster, professor and affiliate chair of the UK Department of Physics and Astronomy. The group features a numerous group of postdocs (Anna Driutti, Ran Hong and Wes Gohn), graduate college students (Abel Lorente Campos, Fang Han, Joel Huether, Laura Kelton and Ritwika Chakraborty) and undergraduate pupil Mitchell Turner.  

“The Muon g-2 experiment has been a great framework for me to dive into the world of data analysis and computational skills in the realm of physics,” stated Turner, who’s a junior physics main. “It has given me insight into the methods used by researchers to further our understanding of the world around us.”

“UK students and postdocs, who represent a diversity of backgrounds, have made truly impressive contributions to acquiring, analyzing and understanding the data from the g-2 experiment,” Plaster stated. “They are those opening this window into the particles and forces of nature.”

With greater than 200 scientists from 35 establishments in seven nations, the Muon g-2 collaboration has now completed analyzing the movement of greater than eight billion muons from that first run. Data evaluation on the second and third runs of the experiment is below means, the fourth run is ongoing, and a fifth run is deliberate. Combining the outcomes from all 5 runs will give scientists an much more exact measurement of the muon’s wobble, revealing with better certainty whether or not new physics is hiding inside the quantum foam.

To study extra in regards to the Muon g-2 experiment, go to

Research reported on this publication was supported by the National Science Foundation below Award Numbers 1812417, 1714014, 1812417 and 1807266. The opinions, findings and conclusions or suggestions expressed are these of the writer(s) and don’t essentially replicate the views of the National Science Foundation.  


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