Lia Merminga Has a Vision for Particle Physics


As a child, she played hopscotch in the Athens suburbs. Now, the Fermilab Director wants the facility to lead the world in neutrino research.

By Sophia Chen | September 9, 2022


Credit: Fermilab

Lia Merminga, Director of Fermilab


Lia Merminga still remembers her first glimpse of the US, as her plane flew in from Greece in 1983. During the descent into New York City, Merminga saw the densely packed skyscrapers of Manhattan.

“I just felt inspired,” says Merminga, who hails from just outside Athens. “I said, ‘My God, how privileged I am.’ I wanted to do something big. I still have this feeling now.”

From there, Merminga went to the University of Michigan, where she earned her physics PhD and began her decades-spanning career to innovate particle accelerators for high energy physics research. She began to lead these efforts, most recently heading the Proton Improvement Plan-II (PIP-II), an ongoing upgrade of the accelerator complex at Fermi National Accelerator Laboratory, outside Chicago. Founded in 1966, Fermilab’s 6,800-acre site has played host to milestone experiments in particle physics, such as the 1995 discovery of the top quark.

This April, Merminga became the new director of Fermilab, the first woman to hold the position. As director, Merminga oversees nearly 2,000 people working on cutting-edge experiments, ranging from the Muon G-2 experiment, whose 2021 measurement of the muon’s magnetic moment may point to physics beyond the Standard Model, to the Long-Baseline Neutrino Facility currently under construction, designed to study properties of neutrinos that could help explain why the amount of matter dominates antimatter—and why the universe exists at all.

Under her leadership, Merminga hopes to solidify Fermilab’s standing as a world leader in neutrino physics for decades to come. “We will do the definitive neutrino experiments here,” she says.

Merminga spoke to APSNews about her life, career, and views on the future of particle physics.

This interview has been edited for length and clarity.

SC: You’re originally from Greece. Can you describe where you grew up?

LM: I was born in and grew up in Chalandri, in a suburb of Athens. I still have many friends living in the area. I grew up playing in the street in front of my house with other kids. We would play tennis, football, and a game like hopscotch. I walked everywhere—to school, to the bakery, to the farmer’s market. The entire city had one high school, and we were divided into girls and boys. The girls would go to school in the morning Monday through Wednesday, and the boys would go in the afternoon. Then the next week, the schedule would swap.

How did you decide to become a physicist?

In Greece, at age 15, you have to decide whether to study the humanities or the sciences. By then, I knew that I loved physics and math. As I look back, I really enjoyed describing a physical phenomenon with the language of mathematics. To me, this was the ultimate form of elegance. I also liked that physics and math problems had a true answer that was not subjective.

My first exposure to science was through stories from my mother and grandmother about my uncle [George Dousmanis], who had a PhD in physics from Columbia University. He was legendary in my family, but he died very young, at age 37 [from a heart attack]. I met him once when he visited from the US when I was two years old, but I have no memory of it. Later on, when I became a graduate student, I got to read some of his physics papers by him. I appreciated how exceptional he was, and how unfortunate his untimely death was.

Also, at age 13, one of my middle school friends gave me a biography of Marie Curie written by her daughter Eva Curie. I just absorbed that book. Then, in high school, I had a fantastic female physics teacher. These all influenced my interest in physics.

You started in theoretical physics as an undergrad at the University of Athens, but then you pivoted to accelerator physics in graduate school at the University of Michigan. What led you to make that change?

I always loved theoretical physics, but it takes so long between developing a theory and experimentally demonstrating it. For example, the Higgs boson was predicted to exist in the early 60s, and it was not discovered until 2012. In between, thousands of people had to build the world’s largest particle accelerator.

When I was in graduate school looking for a PhD thesis topic, my now husband—who was a friend at the time—was a postdoc at Fermilab. He told me about a graduate program in accelerator physics. I realized that with accelerator physics, you can do theoretical physics and validate those predictions using test facilities within months or a year. It also turned out that I love engineering. I decided to go into accelerator physics, and I have been having a blast since then.

Lia Merminga photo
Credit: Fermilab

Merminga (right) and engineer Lidija Kokaska discussing PIP-II, an upgrade of the Fermilab accelerator complex.


What are the big challenges right now in developing future accelerators?

We’ve pushed accelerator performance in terms of higher energy, intensity, and efficiency. A great challenge today is reaching higher energies using more compact machines. The ultimate breakthrough of our field would be to make plasma-driven accelerators [a method that would significantly reduce facility size].

A more near-term goal is to produce more efficient technology to create accelerators that use less energy. I’d like to see more progress on sustainable accelerators.

Without upgraded technology, future colliders would consume enough power for a small town. What are some strategies people are working on to make more sustainable accelerators?

People are starting to make more energy-efficient components, such as superconducting and radio frequency (RF) power sources. The design for the European Spallation Source [a neutron source under construction in Sweden] also collects the waste heat produced by the accelerators and then uses it to heat nearby buildings.

Future proposed colliders include a 100 TeV circular collider, linear electron-proton colliders like the ILC, and muon colliders. What’s your opinion on what the particle physics community should invest in?

For the health of our field, it is incumbent to pursue these design studies of all of these different types. But we still need to resolve significant technical and physics questions for each of these approaches. Fortunately, these approaches require similar research and development. For example, several of them require high field magnets and highly efficient superconducting RF technology. CERN has already chosen to pursue a 100 TeV future circular collider.

What sort of behind-the-scenes activity goes into these huge particle physics projects?

There’s not only a large number of people involved, but also a diversity of expertise and cultural backgrounds. For PIP-II [the upgrade to Fermilab’s accelerator complex], we worked with partners in the UK, Poland, France, Italy, and more. Some are physicists, engineers, technicians, computer scientists, administrators, logisticians, and even import and export control lawyers. This diverse set of people working on a common goal—it makes for such an amazing outcome.

In 2019, at New York Times op-ed kicked off a public debate over whether the science has motivated the need for a larger collider, especially because the price tag is in the billions of dollars. What’s your response to these criticisms?

Colliders are essential instruments that have helped advance our field in a definitive way. The Tevatron, which was the world’s highest energy collider until 2011, helped discover the tau neutrino and the top quark. The LHC discovered the Higgs. In terms of discoveries, those investments have paid off enormously.

Several physicists at Fermilab have drawn attention to anti-Black racism in science. They helped organize a #ShutDownSTEM strike in 2020 and formed a group called Change Now, which wrote a document calling for racial justice and equity at Fermilab. How are you engaging with these issues?

Even before I took over as director, I knew I wanted to listen to our employees, our staff, and our users about the culture at our laboratory. As part of that, I launched what I called listening tours. I meet with groups of 10 to 20 people for 30 minutes to one hour. In our discussions, I mostly listen. My goal is to reach out to every single employee of our laboratory. We’re about now one-third of the way through about 2,000 people on staff. It’s evident that we have work ahead of us.

I’ve read the ChangeNow document and met with members of the group one-on-one to continue the discussion. I want to understand how people feel and what they have experienced historically. This deserves a long-term strategic plan, not a quick fix. I believe fundamentally that we need to have excellence and diversity in our workforce, business, and operations of the laboratory, in order to achieve excellence in our scientific mission. Excellence means an environment where everybody feels they can thrive, that they can advance their career, and they can feel gratification from their work.

Sophia Chen is a writer based in Columbus, Ohio.

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