image: Robert D. “Bob” McKeown has been honored for his outstanding career contributions to nuclear physics with the 2024 American Physical Society’s Division of Nuclear Physics (DNP) Distinguished Service Award.
Credit: Jefferson Lab
NEWPORT NEWS, VA – For nearly half a century, Robert D. “Bob” McKeown has probed nuclear particles and educated rising generations of physicists. Now, the former deputy director for science at the U.S. Department of Energy’s Thomas Jefferson National Accelerator Facility is being honored for his outstanding career contributions with the 2024 American Physical Society’s Division of Nuclear Physics (DNP) Distinguished Service Award.
McKeown is recognized for his work in experimental physics and his extensive leadership in the broader nuclear physics community. Most recently, his leadership roles included serving on the Board of Directors of the American Physical Society (APS) and as speaker of its Council of Representatives.
DNP is a division of APS and comprised of scientists and educators who advance our understanding of the nature of matter down to the quarks and gluons that make up the constituent parts of nuclei and nuclear matter.
“I am very grateful to the DNP leadership for selecting me for this award,” McKeown said. “It has been a great privilege for me to be an active member of the nuclear physics community for now running on 50 years.”
Early in his career, McKeown contributed to the founding and mission of the Continuous Electron Beam Accelerator Facility (CEBAF), which became Jefferson Lab. Later on, he became its deputy director for science in 2010. That year, he was also named the Governor’s Distinguished CEBAF Professor at William & Mary in Williamsburg.
In retirement, he retains emeritus status at both institutions.
“A very important part of my career was teaching and the mentoring of young scientists,” McKeown said. “I supervised 14 Ph.D. students and over two dozen postdoctoral scholars, and many of these people have gone on to very successful careers in nuclear physics.”
In addition, he spent many years teaching and lecturing at the California Institute of Technology.
“There are now thousands of people around the world that I had some part in educating. Beyond the impact on science and technology, it has been great to get to know so many wonderful people,” he said.
Long Island to Jefferson Lab
McKeown grew up on Long Island, the son of an electronics technician in the aerospace industry who nurtured his interest in radio equipment and electronic circuits. In high school, those interests broadened to math, science and physics.
He attended Stony Brook University in New York, where a physics professor inspired him to focus on that field. While he pursued a doctorate at Princeton University, renowned physicist Gerald Garvey became his research adviser and mentor, providing excellent research opportunities to launch his career.
McKeown conducted much of his graduate research work at DOE’s Argonne National Laboratory in Illinois. His experiment there confirmed the weak interaction - or weak force - of the Standard Model of particle physics.
He earned his Ph.D. in 1979, then spent a year at Argonne before taking a position as assistant professor of physics at Caltech. He became a professor there in 1992.
Very early in his career, McKeown was tapped to join advisory committees for national laboratories, including summer study groups for Jefferson Lab in the early 1980s before the facility was even built. Once the lab’s main particle accelerator, CEBAF, was up and running, he was involved in designing early experiments, and for a while headed its user group. CEBAF is a DOE Office of Science user facility and is the research home to more than 1,650 nuclear physicists worldwide.
Eventually, McKeown was tapped by then-lab Director Hugh Montgomery to leave Caltech and become his deputy director for science.
At Jefferson Lab, he concentrated on administrative work, hiring talented people to move the lab forward and advance new mission concepts.
Among his accomplishments, strategic hiring to prepare the lab for its successful bid to lead efforts, along with partner DOE’s Lawrence Berkeley National Laboratory, to build a new $300-500 million High Performance Data Facility at Jefferson Lab.
He also initiated the Laboratory Directed Research & Development program to enable staff to pitch creative ideas to address critical national science and technology problems, and to enable the lab to respond more quickly to timely new opportunities. Now in its 11th year, the lab’s LDRD program recently awarded $3 million for more than a dozen projects in 2025.
And he formed a task force to study future accelerator upgrades at Jefferson Lab, including a new concept using the novel “fixed field alternating gradient” technology to potentially double the energy of the CEBAF accelerator.
A long way
From electron spin, to quarks and gluons, to ghostly neutrinos, nuclear physics has come a long way since McKeown first launched his career.
“When I began my studies of physics, we had evidence that protons and neutrons contained quarks, but there was no theoretical understanding,” he said. “But we soon saw the development of Quantum Chromodynamics (QCD) and have since established an elaborate and elegant theoretical framework, along with experimental techniques, to image the quarks and gluons inside protons and neutrons.”
McKeown has always had a particular fascination with neutrinos, and he counts his participation in neutrino experiments around the world as among his most memorable.
Neutrinos are subatomic particles with so little mass they pass undetected through matter at nearly the speed of light, earning them the nickname “ghost particles.” Even the most powerful detectors have difficulty finding and measuring them. They’re known to exist in three different states, or “flavors.”
“When I was a student, we had experimental evidence for neutrinos from nuclear reactors and particle accelerators,” McKeown said. “An underground experiment in South Dakota saw evidence that neutrinos were produced by the sun in nuclear reactions, but the number of them was too small. We have since established that the neutrinos have mass and can transform between the different flavors, which explains the solar neutrino anomaly.”
Two neutrino experiments in which he participated are standouts for him.
While at Caltech, McKeown and other American collaborators helped Japanese scientists build the KamLAND experiment in an underground facility in Japan.
“That actually showed for the first time that you could see the pattern of the neutrinos oscillating from one flavor to the other,” said McKeown. “And it all looked exactly like the theorists would predict, except we found that the amount of mixing that caused this effect was much larger than they would have predicted, so it was actually a surprise.”
The second breakthrough is the Daya Bay Reactor Neutrino Experiment, an international collaboration near Hong Kong, China.
“We measured the so-called third mixing angle in the neutrino matrix,” McKeown said. “That was very exciting, too, because this really cemented this theory of neutrino oscillations together. It provides the impetus for the new experiments that are being done today.”
As McKeown settles into retirement in California, he’s keeping his hand in the physics field with a new informal affiliation with Berkeley Lab and at the University of California, Berkeley.
“The goals of my work have always been twofold: producing scientific results and advancing the careers of young scientists,” he said. “I take great pride in the fact that I have been quite successful at achieving both of those goals.”
Further Reading
Robert D. McKeown, Experimental Physicist and Leader in National Laboratory Administration
Audio: Robert McKeown is interviewed by David Zierler for the Caltech Heritage Project
By Tamara Dietrich
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