From Liberal Arts to Leadership in Nuclear Physics

Mark Kevin Jones is a true Renaissance man in nuclear physics. Throughout his career, he has garnered many accomplishments, and he’s even worn quite a few hats in his three decades at the U.S. Department of Energy’s Thomas Jefferson National Accelerator Facility.

Jones has been associated with Jefferson Lab since 1992, when he was a postdoctoral researcher working with William & Mary physicist Charles Perdrisat. He has contributed to a number of experiments and is co-author on dozens of papers, including the influential “The Structure of the Nucleon: Elastic Electromagnetic Form Factors,” a review paper in European Physical Journal A with Perdrisat, Vina Punjabi, Ed Brash and Carl Carlson. Jones was a leader in an early Jefferson Lab experiment that measured the ratio of the proton’s elastic electric to magnetic form factors at large momentum transfer using a different experimental technique. The results disagreed strongly with previous measurements and spurred a surge of theoretical and experiment interest. It was one of the most cited publications from Jefferson Lab.  

“That was really surprising,” Jones said. “And we got lucky. In some sense, you have to be prepared for luck. But nature was kind. It made some interesting results. Vina and Charles were generous with sharing the credit. People got excited. And that helped me to be able to give good talks.”

After serving in several postdoc positions, Jones became a staff scientist at Jefferson Lab in 2001. Throughout his tenure, Jones has supported nuclear physics experiments at all stages. Since 2022, he has served as Jefferson Lab’s Experimental Halls A and C group leader, after a time serving as acting group leader. 

Now, Jones has been recognized for his work by his peers by being named a Fellow of the American Physical Society in October 2024 with the citation “For scientific leadership in experimental studies of the fundamental nucleon electromagnetic form factors, including the surprising discovery of significant variation in the large momentum behavior of the proton electric form factor, and for developing new detection systems enabling the studies.” 

An experienced manager and leader

He’s long been a manager as well as an active experimenter, for instance serving five years as program manager of the DOE’s Super BigBite Spectrometer program, overseeing the purchase and construction of magnets and detectors at Carnegie Mellon University and the University of Virginia, as well as at Jefferson Lab. He served two years as commissioning manager of Jefferson Lab’s Experimental Hall C Super High Momentum Spectrometer, working to set up the optics and detectors necessary to get the most out of Jefferson Lab’s upgraded 12 GeV Continuous Electron Beam Accelerator Facility (CEBAF) accelerator.

Jones says these years of experience melding management and experiment prepared him to lead the Experimental Halls A and C group.

Jefferson Lab is home to CEBAF, a DOE Office of Science user facility that is the experimental home to more than 1,900 nuclear physicists worldwide from more than 300 institutions and more than 40 countries. CEBAF shoots a beam of electrons around an oval track nearly a mile around. The beam accelerates with each lap.

When the beam reaches the desired energy level, it’s shunted off into one of four halls. Jones’ purview encompasses Experimental Halls A and C; there also are Experimental Halls B and D. Inside a hall, a beam collides with a designated target, causing a shattering of subatomic particles, which pass through a detector, yielding up clues about the building blocks of the universe.

“I have to make sure we have the right staff covering the beamline, the data acquisition, the detectors and all that,” Jones said. “Also, I have to manage the technical people we have — engineers and designers and technicians — that do all the hard work for us to install the experiments and keep us running.”

It’s a busy existence for Jones, and he says his day in/day out workday responsibilities are probably 70 percent administrative, making it a challenge to maintain an active research program, but the management aspect itself is not too onerous.

“We have great people, so that it’s not so hard to manage when everybody is very take-charge,” Jones said. “That’s the nice part of being at a national lab: People want to be here, and they want to do the best. They’re always going the extra mile to make sure things are working, putting in the extra time and doing whatever they can to make the experiment run well and do the best physics we can do.”

A science frame of mind

Jones was raised in a Philadelphia suburb. His father was an electrical engineer at Westinghouse, working on torpedoes and then turbines. His mother was a homemaker.

Jones says he was interested in science classes in school, but “I probably wasn’t a typical science nerd, always doing science projects,” he added. 

“I liked math, and I liked science, and I would ask for telescopes for my birthday and things like that,” he said. “We had pretty good science teachers, and they had advanced programs where they would have professors from colleges come in.” 

For college, he chose Oberlin College, a small liberal arts school in Ohio that featured a small student-faculty ratio along with a relatively unrestrictive curriculum.

“The great thing about Oberlin at the time was there were no required courses,” Jones said. “You could take, say, a rather upper-level literature class, and not really have to worry about taking the lower-level classes— you could kind of jump around.” 

He majored in physics, and the college’s physics faculty included him on experiments during his senior year. He recalled a demonstration at Oberlin that gave him a tangible appreciation for the laws of physics.

“When you spin a bicycle wheel and you hold it in your hand and then you try to twist it, then you really feel the angular momentum,” Jones said. “It’s a physical thing. You can see the mathematical formula — but to feel it, it’s really there. That kind of made me want to be an experimenter.” 

He said he chose the University of Minnesota for graduate school because it had a large, diverse and well-regarded physics department. Jones said he found a familiar hands-on, small-group working culture.

“That’s where I got into nuclear physics,” Jones said. “I was talking with one professor, and he said, ‘Oh, well, you can come down to Los Alamos for the summer.’” 

So, Jones went down to DOE’s Los Alamos National Laboratory, home of the Manhattan Project. It suited him; Jones said he liked the scientists he met there, and the throughput of pion experiments using the lab’s proton accelerator might have been designed for a Ph.D. student who enjoys working in small groups.

“A typical experiment would only take a week or two weeks,” he said. “So, you were turning over experiments and getting your thesis data pretty quickly. It was exciting, and yeah, it was fun.”

Making the move to Virginia

The Los Alamos facility was winding down about the time Jones had compiled his dissertation data. He joined other Los Alamos physicists looking to make a move. Many of them were aiming to transition to Jefferson Lab.

“Well, it was called CEBAF back then,” he added.

He secured a Jefferson Lab postdoc position, adapting a proton polarimetry technique developed in France by Perdrisat and used at Los Alamos to the Jefferson Lab electron beam. Jones has been at Jefferson Lab ever since and has developed a deep appreciation for the facility’s place in nuclear physics.

“We’re kind of unique in the United States with our high-intensity polarized electron beam,” he said. “I would say, we’re a unique facility for doing QCD physics. There’s some complementarity, and we’re involved in the Electron-Ion Collider up at Brookhaven. But right now, there’s no other facility like us.” 

Further Reading
Jefferson Lab Welcomes a ‘New” Hall Group Leader

Contact: Kandice Carter, Jefferson Lab Communications Office, [email protected]

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DOE’s 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, visit https://energy.gov/science