Assistant Professor Dien Nguyen has won an Early Career Award from the U.S. Department of Energy (DOE) Office of Science, an $875,000 investment in understanding how materials are arranged at the fundamental level.

Giving Order to the Universe

While a touchdown pass or a Smoky Mountain waterfall is a big (and splashy) display of physics in action, Nguyen’s work gets down to the microscopic scale—the nuts and bolts of matter. This is quantum physics, where predictions are difficult to make and events are hard to explain.

An atom is pretty complicated on its own, but its smaller components are even more complex. Inside there’s a nucleus comprising protons and neutrons (known together as nucleons). Nucleons are made up of still smaller particles called quarks, bound together by gluons. Then there’s spin, a fundamental property of nucleons. That’s what Nguyen studies, going a step beyond the basic building blocks of matter.

“It’s not just the building,” she said. “It’s fundamental structure. Spin is responsible for shaping the world—a provider of order and structure to the universe.”

Spin determines, for example, how materials are arranged, down to their most basic level. The more clearly scientists understand how that works, Nguyen said there’s greater potential to apply those findings to fields like materials science, medicine, and quantum computing. Despite its promise, identifying the origin of nucleon spin has been a longstanding challenge in nuclear physics. While physicists have studied both proton and neutron spin, the latter has gotten far less attention.

“Experimentally, neutron spin is way harder to study compared to proton spin,” Nguyen explained, adding that scientists need to understand both to get a clear picture of how matter is ordered. Her work is helping fill the gap by focusing on the neutron at the quark level.

By scattering electrons from a polarized Helium-3 target, Nguyen can provide high-precision data that helps her understand the quark’s internal structure and dynamics (including spin of its own) and how those influence what happens with nucleons. That information helps her map quark spin and how it in turn affects neutron spin.

“I’m bringing missing pieces,” she said. Once all is done, “we should have a much better understanding of the fundamental structure of matter.”

The DOE award will support this work, which includes collaborations with Thomas Jefferson National Accelerator Facility (JLab) and the Massachusetts Institute of Technology (MIT). It will also help Nguyen bring her campus lab up to speed and hire a postdoc and a graduate student so that she can train young scientists in experimental nuclear physics.

A Grateful Vol

Mentoring is a skill Nguyen developed from her own experience. It’s also how she got interested in neutron spin studies.

“I was always interested in this challenging spin study, but did not get a chance to touch it until I went to MIT after my PhD,” she said.

When she was a postdoctoral fellow at MIT’s Laboratory for Nuclear Science, her office was next door to that of Richard Milner, who co-authored a book about physicists’ quest to understand spin and the structure of matter. She began asking him questions about the research and eventually he asked if she wanted to work on a project with him.

“I’m on board,” she told him.

A self-described “hands-on person,” Nguyen said when Milner explained this kind of physics would require a target, she dove in. That was part of her work as a Nathan Isgur Fellow at JLab, where she began working with the Target Group. From there she accepted a bridge position between UT Physics and Jefferson Lab, becoming part of the university’s faculty in 2024.

Nguyen said she’s grateful for the guidance that’s helped define her path. She’s quick to name her advisors: Donal Day, Or Hen, Douglas Higinbotham, and many others, all of whom had different approaches. Some offered unconditional support while others pushed her by setting high standards and tight deadlines. She explained how James Maxwell welcomed her at Jefferson Lab and taught her “everything from the first step about target polarization,” while Milner opened “the bigger view and let you decide what you want to do.”

Taken together, she said, “it’s kind of a mix and really impacted my style of mentoring. I take pieces of that.”

That method has worked well for Nguyen. The UT Graduate Physics Society selected her as their Research Advisor of the Year for 2025.

“This is one of the more important awards for me because it makes me feel like I’m doing things right,” she said. “One of the reasons I wanted to be a professor is that I like to work with students and I like teaching. I put a lot of effort into that. When the students recognize that I care about them, that makes me really happy.”

She’s also not through learning herself. When she first arrived at UT in 2024, Professor Nadia Fomin showed her the ropes of faculty life.

“Nadia taught me a lot,” she said. “She’s a great mentor and I’m thankful to have her here. She took a lot of time on my (DOE Early Career Award proposal) draft and gave me feedback, and I really appreciate that. That was definitely an important piece for this award. I tell her that we won it, not that I won it.”

Nguyen’s success continues an upward trajectory for UT physics in bringing outstanding scientific talent to campus. This is the second DOE Early Career award for the department since 2022, when Associate Professor Tova Holmes won support for her research in elementary particle physics. The program supports outstanding scientists early in their careers whose work furthers DOE Office of Science research priorities.

Professor and Department Head Adrian Del Maestro explained that “Early Career Awards recognize only the brightest and most innovative junior faculty in the United States. Assistant Professor Nguyen is exemplary in terms of both her vision and the impact she has already had on our nuclear physics program. As a bridge faculty, she is representing UT at one of the country’s most elite scientific laboratories. We are excited to see what she will accomplish with this well-deserved award right at the beginning of her career in Knoxville!”

Nguyen said the physics faculty and staff have created a friendly atmosphere that makes coming to work a pleasure.

“I feel welcome when I’m here,” she said. “They make my life here much more beautiful.”

The Pursuit of Curiosity

The need for new models to explain nuclear origins and structure presents a tremendous opportunity for graduate students like Dyszel. He joined Grzywacz’s group in 2022 and was the first author on the Physical Review Letters paper outlining the three discoveries. His to-do list on this experiment was a long one, from constructing physical pieces to interpreting the results. He built frames for the neutron tracking detectors and assembled them in the experimental setup. He set up the required electronics and made beta detectors. He ran test measurements, helped with software for data acquisition, made corrections for optimal timing resolution, and analyzed the experimental data. With all that, Dyszel’s work was still part of a multi-person effort.

“The success of this work is due in part to my colleagues and collaborators, whose guidance and constructive input were crucial,” he said.

A native of Jacksonville, Florida, Dyszel came to UT after finishing a bachelor’s in physics at the University of North Florida. His road to PRL authorship actually began in a general chemistry course when he first learned about beta decay. Intrigued by the thought that nuclear transformations could generate elements with a whole set of different properties, he thought he’d go for a bachelor’s in chemistry.

“It was not until I started my bachelor’s degree that I had stepped foot into a physics class, which instantaneously drove me towards a degree in physics,” he explained. “I’ve always been interested in understanding how the world works, and physics has been, and continues to be, the path I want to follow in pursuit of that curiosity.”

Imagine standing on a seashore, watching the waves roll in. Now imagine trying to describe what’s happening inside a wave, an eddy, and a single drop of water—all at one time.

That’s the kind of challenge Professor Thomas Papenbrock and Adjunct Assistant Professor Gaute Hagen are up against as they calculate physics at different energy scales inside an atomic nucleus. With colleagues from Oak Ridge National Laboratory, Louisiana State University, and Chalmers University of Technology in Sweden, they’ve developed a model that not only computes multiscale physics, but does so drawing from the roots of fundamental nuclear theory.

This kind of research is important because the more researchers discover about the nucleus, the better chance that knowledge can find its way to improving our lives (medical imaging and food safety) and answering bigger scientific questions (what fuels a massive star?). Those applications require understanding the essential properties of these complex systems. 

Calculating Nuclear Waves and Eddies

A nucleus isn’t one simple entity. Inside are protons and neutrons, formed by quarks bound together by gluons. That’s a lot of moving parts for structures so small that a typical grain of sand includes more than 10 million trillion of them.

Papenbrock said that like any system consisting of many particles, nuclei show different phenomena at different length (or energy) scales. To visualize this, consider the ocean. Papenbrock explained that seawater can appear as waves (on the scale of yards), eddies (which can range from tens of yards to inches in scale), and even motions of individual water molecules (microscopic scale).

In a nucleus, different phenomena are realized at different energy scales. At low energy the entire nucleus might rotate. At the next energy level, many (but not all) of the particles vibrate. At even higher energies a nucleus (or a single proton or neutron) could break up.

“The more microscopic the approach one uses, starting at smaller length scales, the more cumbersome it is to compute these collective phenomena, such as eddies and waves in the case of water,” Papenbrock said.

A Computational Two-Step

To tackle this cumbersome task, Papenbrock, Hagen, and their colleagues studied neon nuclei using the power of Oak Ridge National Laboratory’s Frontier supercomputer. In a sort of computational two-step, they captured large energies by including short-range correlations and then computed the details by including long-range correlations. This approach gave them a high-resolution look into the intricate workings inside a nucleus.

A significant achievement in this work is that the team overcame a long-standing challenge in the field by describing multiscale physics with roots in quantum chromodynamics, or QCD. This is the fundamental theory of the strong nuclear force: one of the four forces of physics. It’s part of the Standard Model that describes all known particles and forces: the building blocks of matter and how they interact.

Papenbrock said that “one of the goals in nuclear physics is to describe phenomena starting from the most basic theories: in our case QCD. While we are not yet quite there, we used effective theories of QCD.”

He explained that earlier research computed nuclear binding and rotation energies, but relied on existing theories to model different phenomena at different energy scales. Here, he and his colleagues have developed a unified model that ties directly to bedrock theory.

The findings were published in Physical Review X and selected for a Physics Viewpoint highlight. Learn more about this research from Oak Ridge National Laboratory.

Rebecca Godri isn’t afraid of the hard work needed to test the Standard Model of Physics. As the department’s newest student selected for the prestigious Department of Energy (DOE) Office of Science Graduate Student Research (SCGSR) program, she’s won financial support to pursue this effort at Oak Ridge National Laboratory (ORNL).

Looking for new physics

As part of UT’s fundamental neutron physics group, Godri investigates the weak force, one of the four fundamental interactions in nature. She’s working on the Nab experiment at ORNL; a project designed to discover the nuances of neutron beta decay, a weak process.

A free (unbound) neutron is unstable: it will decay into a proton, electron, and antineutrino. Professor Nadia Fomin, one of Godri’s advisors, explained that “As experimentalists, we can ‘observe’ the neutron spin, momenta of the charged particles, and the angles between them. While the antineutrinos are detectable, the efficiency is very low, and we can get all the necessary information from basic principles of energy and momentum conservation.”

The Nab experiment will make precise determinations of “little a” and “little b,” decay correlation parameters of neutron beta decay. These determinations provide a stringent test for physics beyond the Standard Model.

Flipping the Spin

As small as protons, electrons, and antineutrinos are, the Nab experiment requires mighty tools to study them. Godri is working at the Fundamental Neutron Physics Beamline (FnPB) at the ORNL Spallation Neutron Source, a state-of-the-art facility that directs a powerful neutron stream down beamlines for instruments purpose-built for specific kinds of measurements. As their name implies, neutrons have no positive or negative charge. They do, however, have spin, a magnetic property that points them in certain direction. When neutrons decay, their speed, energy, and direction can give scientists critical information. The FnPB is unique in that can support different experiments with different full-scale apparatus, such as Nab.

Godri’s work, which she recently presented at an American Physical Society meeting, is getting neutrons to reveal more clues about the weak interaction in physics. To do that she’s measuring the residual polarization of the neutron beam at the FNPB and characterizing the Nab experiment’s spin flipper—a device that lets scientists control the neutron’s spin. She works with both Fomin at UT and Chenyang Jiang, a research scientist in ORNL’s Neutron Technologies Division.

While some may find all the preparation tedious, Godri said she enjoys both the groundwork and the payoff.

“The hands-on work is exciting,” she said. “My favorite part is being able to get data from the measurements we’ve spent months preparing for!”

An Easy Decision

Godri earned a bachelor’s degree in physics from the University of Tennessee at Chattanooga in 2021 and started her graduate studies in Knoxville that fall. She finished a master’s in physics last year and is working toward a PhD.

UT’s nuclear physics research opportunities made it an obvious choice for her graduate studies.

“Nadia’s research at ORNL aligned with my research interests post-undergrad, so UT was an easy decision,” she said. Godri’s SCGSR award is the 14^th for UT Physics since 2016 and the fifth this year. She’s part of the latest cohort, comprising 62 PhD students from 24 states

Imagination, quite literally, made Lindsey Hessler a Vol before she even started high school. Now a UT senior, she has won an assistantship from Jefferson Lab to support her research in nuclear physics.

It’s the Small Things in Life

Hessler said her interest in physics came about because she is “incredibly fascinated by the intricacies of the universe and understanding how the small things in life work.”

During COVID she spent hours on YouTube watching videos about stars, galaxies, energy—anything explaining the building blocks of our world and universe.

For nearly a year she’s been working with Professor Nadia Fomin and Assistant Professor Dien Nguyen as part of the nuclear physics research group. She was one of the department’s 2024 Summer Research Fellows and learned in August she had won a Jefferson Science Associates Minority/Female Undergraduate Research Assistantship.

The program supports minority or female undergraduates working on projects that are part of the Jefferson Lab research program or are directly related its scientific or engineering aspects. Situated in Virginia, this United States Department of Energy facility is a leader in accelerator science, dedicated to probing the particles and forces that comprise and govern the matter that makes up our world. With this award, Hessler will contribute to the lab’s scientific mission.

“This assistantship will cover a variety of projects,” she explained. “I will be working to collect data with a Helium-3 Polarization apparatus as well as developing a projection of runtime for upcoming experiments at CEBAF (the Continuous Electron Beam Accelerator Facility).”

Her physics studies are driven by a creative and curious worldview that began when she was still in middle school and ultimately brought her to Knoxville.

Solving Problems in the Lab and Industry

Hessler is from Germantown, Wisconsin, but early on her college die was cast in Tennessee orange.

“I chose UT because as a kid I was involved in a competition/club called Destination Imagination (DI),” she said. “The Global Finals were held at UT after the college semester ended, so I spent a week in the dorms at age 12 and fell in love with the campus, ambience, and culture in Knoxville. Ever since then I was determined to be a Volunteer.”

She explained that she began her UT studies as a management major but quickly discovered she had a knack for science.

“At this point I had a decent amount of business classes completed (so) I decided to add physics as a second major,” Hessler said. “I have loved learning two very different studies and have found that both educational paths teach me how to work through problems (and life) in very different but beneficial ways.”

Despite the demands of a double major in business administration (management) and physics, she’s on track academically and said that “ideally (she) will be graduating next December holding a diploma from the Haslam College of Business and UT’s College of Arts and Sciences.”

Her plans include going on to graduate school with a focus on nuclear physics, using the full advantage of her combined majors to design her career.

“I would love to work in the energy and/or defense industry and apply my physics degree as well as my BS in management to project management and operations,” she said.

From her first days as an imaginative kid visiting campus, Hessler has followed her passion and is headed for a promising next destination as a nuclear scientist.