image: UT Professor Tova Homes has won a prestigious Cottrell Scholar Award.
Credit: University of Tennessee
Tova Holmes is a big fan of tiny particles. She’d like it if you were too. An assistant professor of physics, she’s won a prestigious Cottrell Scholar Award to help her move physics forward while inspiring a larger cheering section for all science.
The Cottrell Scholar Awards recognize outstanding early-career teacher-scholars in chemistry, physics, and astronomy. Holmes is the first UT faculty member to win a Cottrell Award and one of 19 awardees in the 2024 cohort, each of whom receives $120,000 over three years. The goal is to support young scientists with innovative ideas who also have a gift for academic leadership. Each scholar writes a proposal for research and one for education. Holmes, who joined the faculty in 2020, is passionate about both. In 2023 UT’s physics majors selected her as their Research Advisor of the Year. As a Cottrell Scholar, she’ll teach students how to explain their work to a wide audience, as well explore new ground for her own.
In the Room Where it Happened
In the early hours of July 4, 2012, Holmes, then a sleep-deprived graduate student, managed to get one of three remaining seats in the CERN auditorium to hear the official announcement that the Higgs Boson had been discovered. The confirmation of this elusive particle, predicted 50 years earlier, completed the Standard Model of Physics. So on “Higgsdependence Day,” as she called it, Holmes was there, “at the center of discovery.” She was hooked.
Elementary particles are a bit like prime numbers. If you’re dividing a huge number, there comes a point where you can’t break it down any farther because the numbers left are indivisible. Atoms are sort of the same. Dividing an atom into its most minute components and figuring out how they work (or if there are more of them) takes scientists down to the bedrock of matter and tells them something about the universe, most of which is still a mystery. While the Standard Model organizes all the particles and forces governing matter, Holmes has set her sights on one: the muon.
Making Custom Particles
Digging down to matter’s foundations involves building high-energy colliders that accelerate beams of particles and then smash them together. Physicists wade through the aftermath, measuring the location and energies of known particles and looking for new ones. The Large Hadron Collider (LHC) at CERN has been remarkably successful at this, as evidenced by the Higgs discovery. But what comes next?
The LHC is a 27-kilometer underground ring crossing the French-Swiss border, hemmed in by mountains and Lake Geneva. To take the science farther and work at higher energies, the ring would have to be bigger. Holmes, however, is among the physicists who see energy, rather than real estate, as the solution. The muon is the key.
Muons are 200 times heavier than electrons and offer more energy for collisions. They also come with challenges. Particles in collision beams have to be aligned and headed in the same direction. For that to work, every collider up until now has used stable particles, like the protons at the LHC. Muons are more complicated. First, they have to be created by sending protons through a scientific obstacle course that begins with a linear accelerator and ultimately creates particles called pions, which decay into muons.
“They’re bespoke particles,” Holmes said. “You have to make them because they’re not sitting around. Then you have to deal with them in whatever state they’re in. (And) they only live about two microseconds.”
Before the muons decay, scientists have to compress them to fit into a beam, point them in the same direction, accelerate them, and finally collide them.
“That’s going to make things tricky,” Holmes said.
She’s is part of a growing group with a plan to navigate this tricky territory. Using magnets to collect the muons, they can slow them down by shooting them into a material, then accelerate them in one direction to align them. This is only one part of a muon collider, but by showing proof of principle, they move closer to making the technology a reality.
Their timing couldn’t be better.
The US particle physics community sees the muon collider as a centerpiece of the field’s future, as outlined in the scientific roadmap they announced last year. The Cottrell Award helps support Holmes’s postdocs and students so they can contribute to this work.
“What they’re currently doing is muddling their way through some pretty rough code that’s sort of been borrowed and adapted, and trying to squeeze information out of it about what kind of physics we can do,” she said. “We need to (make) that a more streamlined process. The proposal is really about engaging in that.”
Department Head Adrian Del Maestro said Holmes “is unique in her ability to inspire and challenge students to seek answers to some of the most fundamental problems in physics. She is an international leader in envisioning the future of the facilities needed to discover new particles, making the University of Tennessee a ‘theory of everything’ school.”
Getting the Message Across
Holmes’s students have joined a field that’s highly collaborative. She said creative thinking and effective communications are crucial in research areas like hers that involve thousands of scientists from across the world. Yet she’s seen that students typically don’t get the chance to develop those skills in the mainstream physics curriculum. Not only does this discourage students drawn to those ideas from majoring in physics, it also leaves physics graduates at a disadvantage.
“You’re not going to be good in my field if you can’t communicate to nearby experts,” she explained, adding that half of success in particle physics is explaining how what you learn is useful to others.
“(Communication) is not an afterthought: it’s a fundamental requirement,” she said. “My field’s not the only one that’s like that.”
Holmes was impressed by Professor David Matthew’s architecture and interior design students as she watched them brainstorm, refine, and work together to solve problems. She took notice of Senior Lecturer Sean Lindsay’s innovative course using science fiction to teach physics. Both also use a grading system outside the traditional instructor-assigned scores, encouraging students to self-assess and review one another’s work. She’s brought Matthews and Lindsay on board as collaborators as she uses her Cottrell Award to develop a special topics course.
Students will learn the basics of strong visual, written, and spoken communications. They’ll study design elements to make compelling graphics for their data and practice translating technical concepts into simpler language. Their final project will be convincing a non-scientist to see the value in science.
Holmes knows first-hand that discovery must be shared if it’s going to be appreciated. She’s been quoted in The New York Times, Nature, and Science about the possibility of a muon collider and what it means inside and outside the research community.
“If I want to get a multi-billion-dollar machine built in the US, I need to be able to communicate why that’s something that’s valuable to everybody in the US,” she said.
A Career Well Spent
Holmes is excited to broaden her own collaborations now that she’s part of the Cottrell Scholars community. Current and former scholars meet each year and build connections outside their typical research areas. While she has a scientist’s natural curiosity and open mind, her hope is that particle physics—driven by a new muon collider—will keep her occupied for the foreseeable future.
“That is my dream,” she said. “I think that would be a career well spent.”