Jean-Paul Richard, 1936 - 2023

Professor Emeritus Jean-Paul Richard, an experimentalist with numerous contributions to the understanding of gravity, died on September 6, 2023. He was 87.

A native of Québec City, Québec, Richard studied at the Université Laval before moving to France for his graduate work. Following doctoral studies in theoretical physics and physical sciences at the Université de Paris, Richard accepted a postdoctoral position at the University of Maryland in 1965. At that time, Joseph Weber was working to detect gravitational waves, which had been predicted by Albert Einstein but never confirmed.  

Following his postdoctoral appointment, Richard accepted a position as an Assistant Professor at UMD, where he would spend his entire career. Over the next three decades, he contributed to several developments, including Apollo 17’s  Lunar Surface Gravimeter.  

In addition, Richard worked to increase the sensitivity of Weber’s aluminum bars by developing a resonant capacitor transducer using field-effect transistors. He also developed a multimode detector achieving higher sensitivity over a wide band of frequencies, and then calculated improvements in the multimode detector by using an optical sensor.

Richard enjoyed visiting appointments at Rome’s La Sapienza and the Université Laval. After his retirement in 1995, he continued his work for three years as a UMD research scientist.

Though early UMD efforts never captured gravitational waves, scientists adapted and persisted. In late 2015, the LIGO experiment succeeded in detecting gravitational waves generated by the merger of two unimaginably distant black holes.

Reflecting on his work after the announcement, Richard said, “When I heard the LIGO news, I was shocked and stunned for a couple of days. It gave new value to my work and justified my efforts. That’s a very big thing."

Funeral arrangements are shown here:

Ph.D. Student’s Initiative Led to Numerous Research Collaborations and Accolades

A big part of research is working with other scientists. As an undergraduate and graduate student at the University of Maryland, Jacob Bringewatt (B.S. ’18, physics) put in the work knocking on doors and connecting with professors, which allowed him to explore a broad range of research projects and earned him accolades along the way.Jacob Bringewatt  Jacob Bringewatt

Bringewatt was torn deciding between a small liberal arts college and a bigger state university for college. He came to UMD to interview for a Banner/Key Scholarship and during the visit he spoke with Physics Professor Tom Cohen. Cohen emphasized that a strong research program—like the one UMD has—is an important component of a high-quality physics education. That conversation—and receiving the scholarship—pushed UMD to the top of Bringewatt’s list, and he enrolled in 2014.

As an incoming freshman, Bringewatt was eager to dive into theoretical physics research. During the first couple weeks of classes, he sought out Cohen to ask about joining a theoretical research project.

“He told me that I shouldn't do theory, even though he's a theorist,” Bringewatt said. “One should only do theory if they're like really bad at experiments or can't imagine doing anything else. I’ve learned since this is his standard line for eager undergrads.”


Bringewatt took Cohen’s advice and sought out an experimentalist: Physics Professor Carter Hall. Bringewatt joined Hall’s team and initially crunched numbers—analyzing experimental data instead of getting his hands dirty with experimental equipment. He eventually handled equipment in the lab and quickly realized it wasn’t for him. He still felt drawn to the math and theory side of physics. So he returned to Cohen, who directed him to Physics Professor William Dorland who was on sabbatical at the time. 

The summer before his junior year, Bringewatt wrote some computer code for Dorland to use in an ongoing project investigating how plasmas move. Dorland, who is a computational physicist, was interested in quantum computing and decided to spend some of his time during his sabbatical exploring the basics of quantum computation with Bringewatt. Their discussions developed into a collaboration with Stephen Jordan, who was then an adjunct associate professor of physics at UMD. The group investigated adiabatic quantum computation—a version of quantum computing that involves gradually evolving one quantum state into another. Bringewatt was the first author of a paper the collaboration wrote comparing the adiabatic quantum computing approach to a classical alternative. The experience focused Bringewatt on theoretical physics.

“I haven't really looked back since then,” Bringewatt said. “Maryland is a really good place to be for quantum computing. And, as a highly interdisciplinary field, it really does bring out the things I like most about research.”

Having settled on studying quantum theory, Bringewatt still had to decide where to attend grad school. UMD’s many experts and diverse research opportunities once again moved it to the top of his list. But he wanted to experience working in another group. So, before he graduated in 2018, he started visiting with professors. He found a match that felt right with Alexey Gorshkov, an adjunct associate professor of physics at UMD, and his group, which works on a broad range of theoretical physics topics.

During graduate school, Bringewatt has continued investigating adiabatic quantum computation, including collaborating with Michael Jarret (Ph.D. ’16, physics), who is now an assistant professor in the Mathematical Sciences Department at George Mason University. Together, they wrote a paper comparing classical and quantum adiabatic techniques for simulating quantum physics

Bringewatt also took on other challenges. A significant portion of his graduate research focuses on using quantum physics to push the limits of measurement technologies. This research involves improving sensor precision by optimizing the use of quantum entanglement—a fundamental quantum phenomenon that connects quantum particles and allows them to ignore some constraints of classical physics. The work looks at the smallest parts that contribute to a sensor, how the pieces interact, and how they come together during a measurement. By understanding sensors at this fundamental level, future technologies might be able to operate at the limits of what is allowed by physics.

Bringewatt shared this part of his research during the 2022 Three-Minute Thesis (3MT) competition hosted by UMD. 3MT competitions are hosted by many universities around the world to encourage graduate students to practice communicating technical research clearly and succinctly. In these events, the competitors distill a research project into a three-minute presentation that is accessible to someone unfamiliar with their field. Bringewatt was one of the eight winners in the campuswide competition, earning him a $1,000 prize. 

Jacob Bringewatt  delivers his 3-minute thesis.Jacob Bringewatt delivers his 3-minute thesis.“It was a fun challenge to explain in three minutes the big ideas behind a line of research I've been pursuing for several years with a number of excellent collaborators in Alexey Gorshkov's group,” Bringewatt said. 

As part of one of his projects on quantum sensor networks, Bringewatt, Gorshkov and UMD physics graduate student Adam Ehrenberg investigated the peak performance that networks of quantum sensors can achieve. His project built on previous work that had already established the best performance that is physically possible. Crucially, those results had assumed the maximum amount of entanglement—all the sensors are always connected to all the other sensors. But practically achieving maximum entanglement is difficult work, so Bringewatt and colleagues flipped the problem on its head. They identified the minimum amount of entanglement needed to achieve an optimal measurement, which for some cases didn't require maximum entanglement. They then developed protocols that achieve the theoretical target they had set. The team’s efforts earned them a place among the 12 groups of finalists for the 2022 UMD Invention of the Year Award.

"I'm honored to have gotten a chance to collaborate with Jake on many projects,” Gorshkov said. “I learned a lot from him and am very proud of his numerous achievements and well-deserved awards."

Even while juggling classes and research into both quantum sensors and adiabatic quantum computing, Bringewatt sought out new challenges. For his first four years as a graduate student, he was a Department of Energy (DOE) Computational Science Graduate Fellow. The program requires fellows to spend a summer working at a DOE laboratory, and it encourages them to explore new topics. 

Bringewatt was eager to try something completely new. He knew Zohreh Davoudi, associate professor of physics at UMD, from his undergraduate math methods course. And he was aware she studied nuclear theory and was interested in branching into quantum simulations. He thought a summer of nuclear theory might be interesting and have the additional benefit of providing a foundation to work with Davoudi. So, the first summer after starting graduate school, he requested to spend his summer at Jefferson Lab, which is home to a particle accelerator used for nuclear physics experiments. 

He spent his summer there as part of a team investigating the internal structure of protons. This small sample of nuclear physics research left Bringewatt eager for more, so he reached out to Davoudi. The timing worked out: She was looking for colleagues to collaborate with on developing quantum simulations of nuclear physics

He began attending Davoudi’s group meetings, and they eventually began pooling their skills on a project. Earlier this year, they published a paper on finding the best way to represent fermions—particles like electrons that can’t share their quantum state—and their interactions within quantum computer simulations. 

The topics of nuclear theory, quantum sensor research and adiabatic quantum computing have given Bringewatt diverse challenges and experiences throughout graduate school. As a result of his prodigious work ethic, he has been first author on ten research papers—an unusually high count for a graduate student.

“Being able to pursue these three distinct topics has been a real advantage of being here where there's a lot of experts on a wide array of things,” Bringewatt said. “I've gotten the chance to work with a lot of talented people with different areas of expertise, which has been really nice.”

Earlier this year, the College of Computer, Mathematical and Natural Sciences acknowledged his hard work and gave him the 2023 Board of Visitors Outstanding Graduate Student Award and a $5,000 prize. 

“I feel very honored to have received this recognition,” Bringewatt said. “Scientific research is never an individual effort, and having pursued both my undergraduate and graduate degree at the University of Maryland, I am extremely grateful to the university and all my mentors here who have enabled me to grow and excel as a young scientist.”

Bringewatt is wrapping up his research at UMD and looking for new collaborations and challenges as a postdoctoral researcher. He plans to graduate in the spring of 2024.

“I've been very happy to be at UMD,” Bringewatt said. “It's a great community, and, I think, the best of both worlds: It has a bunch of resources and world-class research, but people are also very approachable, friendly, and helpful. I feel extremely lucky for the years I’ve gotten to spend here.”

Written by Bailey Bedford


Related news stories:


From Particle Physics to Artificial Intelligence

Brian Calvert (Ph.D. '15, physics) grew up in southern Colorado in a rural community where “big world” opportunities were few and far between.

Brian CalvertBrian Calvert

“Right before you hit New Mexico there’s a tiny little town called Trinidad and we moved 40 miles northeast of there to the total boonies,” he recalled. “Our closest neighbors were a quarter of a mile away, we had no running water and no central heat. It was pretty wild.”

Calvert’s surroundings back then may have been simple, but his dreams were definitely not. As a teenager inspired by the problem-solving power of science and mathematics, he knew he wanted to take on challenges that impact people’s daily lives. But even he couldn’t have imagined that 20 years later he’d be blazing a trail on the cutting edge of artificial intelligence (AI) as co-founder of the San Francisco tech startup Graft.

“I had heard about robots and AI in the context of science fiction stories as a kid, but I had no exposure to what it meant to work on AI as it was back then,” Calvert said. “And AI has gone through such a massive renaissance that I'm not sure I could have imagined I'd work on it in the capacity that I have. But it’s exactly where I want to be.”

At Graft, Calvert is on a mission to make a difference by making AI more accessible.

"A lot of companies like nonprofits would love to be able to capitalize on the power of AI for their data, often for very clear social good, but it’s just really hard for them to do it—there are a lot of barriers to entry,” Calvert explained. “The core idea here is to help democratize access to the state-of-the-art infrastructure and techniques that are powering the AI giants of the world; let’s bring that to everybody else. That’s our mission: the AI of the 1%, for the 99%.”

Starting with physics

Calvert’s interests began with physics, first as an undergraduate at Princeton and then as a Ph.D. student at the University of Maryland. At UMD, Calvert quickly connected with Physics Professor Emeritus Nicholas Hadley. Intrigued by Hadley’s work in experimental particle physics, Calvert joined the CMS experiment at CERN, working in an inspiring collaboration with thousands of other scientists around the world to search for new physics at the world’s highest energy accelerator. Contributing to the 2012 discovery of the Higgs boson—the fundamental particle that enabled matter to form after the Big Bang created the universe billions of years ago—helped to focus the trajectory of Calvert’s Ph.D. dissertation research from 2013 through 2015.

“After the Higgs boson discovery, there were still more unanswered questions. One really elegant way to address a bunch of these questions is to introduce this notion of supersymmetry, where every fundamental particle has a mirror version of itself. If supersymmetry is correct, then we should find signatures of these supersymmetric partners,” Calvert explained. “Specifically, I was looking for the top squark, the supersymmetric partner to the heaviest fundamental particle, the top quark. For context, the two lightest quarks, the up- and down-quarks, are the primary building blocks of protons and neutrons, and the top quark can be thought of as the big brother of the up quark. If I could just find the top squark it would answer many other questions about the building blocks of the universe.”

Through his research in particle physics, Calvert saw the cross-disciplinary problem-solving power of science and mathematics in a whole new light.

“These particle physicists were working on algebraic stuff and math like I’d never seen and a bunch of computer science, too,” Calvert said. “We were analyzing petabytes and petabytes of data and there was a lot to the software part of it, like how do you analyze that much data at scale, particularly in the context of some problem you’re trying to solve. It’s like climbing a mountain. But it’s a mountain you want to climb.”

Wafers, hearing aids and self-driving cars

After earning his Ph.D. in 2015, Calvert landed a job as a senior imaging scientist at Intel’s wafer fabrication and manufacturing facility in Hillsboro, Oregon, working on the design of lithography photomasks used to print computer chips and performing large-scale analysis of electron microscope wafer images. At the time, concepts like machine learning (ML) and deep learning and the overall idea of AI were beginning to gain momentum and Calvert realized his skill set was a good fit.

He moved from Oregon to San Francisco to pursue opportunities in the space starting with some contract work building deep learning models for an audio detection system designed to enhance the function of hearing aids. In 2017, he went all in on ML and AI as a data scientist at Cruise Automation, a self-driving car company.

“That was a transformative experience,” Calvert recalled. "I initially worked on assessing the safety of the cars with a combination of ML and statistical models using data collected across the entire fleet of cars, then focused more on scalable data and machine learning infrastructure, as I knew from my Ph.D. experiences how important that was. That work got the attention of engineering leadership, and I was chosen to lead the whole overall machine learning infrastructure team. This included the AI models running on the car making real-time, safety-critical decisions and models running in the cloud analyzing data from the entire fleet. My team was building the structure to support that at scale and the work really energized me.”

After four years at Cruise, Calvert met Adam Oliner, CEO of Graft. Excited about the possibilities ahead, Calvert joined the company as a co-founder in 2021.

“I definitely think AI is the future,” Calvert said. “Humans keep generating data at larger and larger rates, so AI has to be the future. There’s no way you can manually process that much data at scale, nor should you.”

Graft’s aim is to create AI technology that can quickly perform large-scale analysis of unstructured data—including text, images, and graphs—to meet the needs of any client, whether it’s a customer-driven sales business or a search-and-rescue team trying to locate a missing hiker.

“Whether it’s a lost hiker and there are miles and miles worth of images to search through or it’s a business that wants a real-time customer churn prediction, Graft provides a platform,” Calvert explained. “You connect us to your data, we have ML science modeling experts and ML infrastructure experts on staff, and our system provides an automated workflow to help you get to the goal.”

The company—and venture capital support for its mission—have already come a long way.

“We did a pre-seed round of $4.5 million a few years ago in early 2021 and then we just closed a seed round of $10 million, so we’re at $14.5 million in venture capital funding so far,” Calvert said.

Though Graft’s AI platform is still in beta testing, Calvert is optimistic about the future.

“We ran a private beta starting in fall 2022. After the feedback from this beta, we've now expanded to a wider, controlled rollout,” he said. “We definitely think we have a product that people would pay money for.”

A strong foundation

For Calvert, Graft’s mission of bringing the capabilities of the world’s biggest AI companies to every business is as demanding as it is inspiring. He’s quick to point out he never would have gotten here without physics and his time at UMD, which provided a strong foundation for the challenges he faced on every step of his journey.

“150,000%—UMD helped me grow in so many ways,” Calvert noted. “My Ph.D., which focused on experimental particle physics, was effectively a data science Ph.D. It gave me higher-order systems-level thinking that I draw upon all the time, as well as statistics and large-scale data analysis and AI/ML skills. I’m really grateful for that.”

Twenty years ago, Calvert never could have envisioned a future in AI—now he can’t imagine being anywhere else.

“I couldn’t really see myself doing anything else right now,” Calvert reflected. “Will it be that way forever? Maybe, maybe not. Either way, right now this is a really good place for me to be.”

Written by Leslie Miller

Physics on the Field

On a Saturday in April 2023, an unusual event unfolded on the grassy greens by the University of Maryland’s Memorial Chapel. Nearly 50 students, staff and faculty gathered to play in the inaugural Physics Champions League, an amateur soccer tournament run by the UMD Physics Undergraduate Committee (PUC). Created to bring together waldych soccer 2physics majors looking for some outdoor fun, the tournament also welcomed the greater campus community, plus friends and family, to participate.

For junior physics major and PUC co-president Sarah Waldych, the idea for the tournament began last fall when she overheard classmates chatting about soccer between classes.

“I realized that a lot of us enjoyed playing soccer in our free time. Many physics majors are involved in intramural sports,” Waldych explained. “Once that clicked, it seemed so obvious to me that we had to organize a way for all of us to come together and just have fun. And it just took off from there.”

Waldych still remembers the excitement and cheering crowds from that spring afternoon. She and other PUC members ran the whole event, from facilitating team sign-ups to refereeing the games. Although many of the players were physics undergrads, graduate students, non-physics students and even a faculty member—Physics Assistant Research Professor Chandra Turpen—played on the soccer pitch that day. 

The Physics Champion League is just one of Waldych’s ideas on how to connect students outside of the classroom and build a better, stronger, tighter-knit physics community. As a member of PUC, Waldych helped organize many other programs and events for physics majors—from free hot chocolate and games during exam times to undergraduate research colloquia that help students practice their presentation skills. 

“Growing up, I realized that there wasn’t much of a science community for me to really share my experiences with. In fact, there’s sometimes a taboo about physics; it’s too hard, too intimidating, too unwelcoming, or not fun at all,” Waldych explained. “I want to help create a space where we can gather, get to know each other, share research or present anything that we find interesting, and help each other grow.” 

To reach those goals, Waldych often collaborates with Donna Hammer, the director of education programs and public engagement in physics and PUC advisor. Together, they work with students, faculty, staff and alums to ensure their needs—both research-related and recreational—are met. Hammer believes that Waldych’s work is essential to maintaining a physics community that is both vibrant and diverse. 

“Sarah’s sincere and tireless effort to make sure all physics majors feel included and their accomplishments celebrated is truly outstanding,” said Hammer. “She’s not only committed to her studies and research but also to her peers and the broader physics community.”

A journey to Germany

This summer, Waldych focused her outreach efforts on the broader physics community, spending two months in Hamburg, Germany, at the Deutsches Elektronen-Synchrotron (DESY), a national research center operating particle accelerators and conducting groundbreaking research in particle physics. Waldych worked with the Compact Muon Solenoid (CMS) experiment, a general-purpose detector at the Large Hadron Collider that can see a wide range of particles and phenomena produced in high-energy collisions.

Waldych, wearing a special gown, hairnet and gloves, is applying isopropyl alcohol to a cloth that will be used to clean all the equipment before an experiment. All the experimental work is performed in a clean room to prevent extra dust or oils from contaminating a very sensitive thermal experiment inside the vacuum chamber. Waldych, wearing a special gown, hairnet and gloves, is applying isopropyl alcohol to a cloth that will be used to clean all the equipment before an experiment. All the experimental work is performed in a clean room to prevent extra dust or oils from contaminating a very sensitive thermal experiment inside the vacuum chamber.

“I worked with the scientists at DESY and students from all sorts of backgrounds,” Waldych said. “We analyzed the systematics of a custom experimental setup designed to measure a sample’s thermal conductivity, or its ability to conduct or transfer heat. We studied the behavior of sapphire glass under multiple operating conditions and specialized criteria that aren’t usually recognized in commercial settings. Our findings will be used later to calibrate other experimental setups at DESY.” 

Waldych will bring her new knowledge and hands-on experience with particle physics back to Physics Assistant Professor Christopher Palmer’s lab, where she studies the Higgs boson, an elusive elementary particle believed to be linked to a field that gave mass to everything in the universe.  

“Sarah truly has the potential to become a great physicist,” Palmer said. “I hope that this program gave her the opportunity to see what being a particle physicist is like in the real worldbeyond the classroom.” 

Waldych hopes that she can apply the skills she learned in the lab to practice as a researcher. And she’s hopeful her experiences will also help her develop new plans to make physics more fun and welcoming when she returns to Maryland. 

“I’ll still be coming up with ways to support UMD Physics, including holding another Champions League—which we would like to run again next spring—and also promoting immersive learning experiences like the DESY program to other students like me,” Waldych said.


Written by Georgia Jiang

Brian Clark Hunts for the Most Elusive and Energetic Neutrinos

Brian Clark, a new assistant professor of physics at the University of Maryland, arrived with a mission: to detect the first ultra-high-energy neutrinos.

If spotted, these tiny, almost weightless particles that pass through matter with barely any interactions could offer a new lens through which to view the universe. The highest-energy neutrinos have about 100 times more energy than any of the particles speeding through the Large Hadron Collider, the world’s highest-energy particle smasher running underneath the France-Switzerland border. And scientists think that the energetic neutrinos are created by astrophysical events that might not leave any other detectable trace. 

“I think the general theme of the work I do,” Clark said, “is that anytime you have a chance to look at the universe in a new way, you tend to learn something. So, I'm pro finding new ways to look at the universe.”

Brian Clark

Clark brings to UMD a wealth of experience, a reputation of excellence in mentoring students and a history of leadership within scientific collaborations. His passion for looking at the universe in novel ways and for community building dates back to his undergraduate years studying physics at Washington University in St. Louis. 

During his freshman and sophomore years, Clark had a few false starts. He wasn’t a fan of quantum mechanics for its reliance on mathematical tricks and worked in a couple of condensed matter physics labs that left him unexcited. Then, he stumbled into the astrophysics research group of Physics Professor Henric Krawczynski, who was working on detecting the polarization of celestial X-rays—Clark’s first exposure to a new way of looking at the universe. 

“What really caught me with that project was how well astrophysics as a concept integrated the physics,” Clark recalled. “It doesn't utilize just one branch of physics—you have to think really cross-disciplinarily. You need to know statistical mechanics and electromagnetism and a little bit of dynamics to put all of these stories together. And I enjoyed thinking broadly in that sense.” 

In Krawczynski’s group, Clark contributed to the development of a new method for analyzing data from a type of telescope that didn’t yet exist. This type of telescope, known as an X-ray polarimeter, would look at the polarization—or orientation—of X-ray light. While X-rays coming from remote reaches of the universe have been detected before, pinning down their polarization had always been difficult. Nevertheless, polarization was expected to carry extra information about the source of the X-rays, potentially elucidating things like the way matter collapsed into a black hole. Recently, an X-ray polarimeter called IXPE launched into orbit, and the work Clark contributed to has emerged as the main data analysis method for scientists using the telescope. 

“It's been fun to watch the citation count tick up,” Clark said. 

In his undergraduate years, Clark also participated in many community-oriented activities. He was a residential advisor at his dorm and volunteered as both an orientation leader and a tour guide. During his senior year, Clark was torn between his passion for physics and his enthusiasm for community building. He applied to physics and higher education administration graduate programs. However, he couldn’t imagine leaving science altogether. By the end of his senior year, he firmly settled on physics. 

Clark enrolled at Ohio State University and joined the group of Physics Professor Amy Connolly to work on what would become the subject of his career—high-energy neutrinos. 

“He walked in my office looking for a spot and he was just glowing with enthusiasm, like he always is,” Connolly recalled. 

With Connolly’s support, Clark landed a National Science Foundation Graduate Research Fellowship to support his studies. 

“Neutrinos are really young as a discipline, especially high-energy neutrinos,” he said. “They're a pretty new way of looking at the night sky. And that was really intriguing to me. It’s a really nascent field that's just finding its feet.”

Neutrinos are a peculiar type of particle. Of all the particles that have mass, they are the lightest. They have no electrical charge and only interact weakly via gravity and the nuclear forces responsible for radioactivity. Because of this, they largely pass through matter, including humans, unimpeded, which has earned them immortality in a poem by John Updike. It’s estimated that 100 trillion neutrinos pass through you every second.

The reluctance of neutrinos to interact with anything else meant that they remained undetected until 1956. But once they were discovered, it didn’t take long for scientists to conceive of using neutrinos as a sort of telescope to look at the universe. Scientists first spotted neutrinos coming from the sun in 1968, but it took until 2013 for anyone to find neutrinos originating from outside the solar system. These were detected by an experiment called IceCube, located at the South Pole in Antarctica. 

The basic idea of the IceCube experiment is simple: Neutrinos almost never interact, but one way to catch them is to provide a really big target and wait around for signs that a neutrino smashed into it. Luckily, the big target already exists—ice around the South Pole is dense enough to provide a decent chance of interaction, and there’s lots of it.  So, scientists buried detectors deep into Antarctic ice sheets. If, by chance, a neutrino comes close enough to one of the atomic nuclei inside the ice molecules, it will cause something akin to an explosion, sending out a shower of particles and radiation, from flashes of optical light to radio waves. 

The IceCube detectors capture the light, which indicates what direction a neutrino came from and how much energy it had. This provides a new way to look at the universe, distinct from optical imaging with tools like the James Webb Space Telescope or gamma and X-ray detectors. Neutrinos carry information about powerful cosmic events, like exploding stars and black holes, that are hard to see by other means. 

IceCube’s method for detecting astronomical neutrinos works well for neutrinos that carry up to about a trillion times the energy of a typical electron meandering around a hydrogen atom. But for the ultra-high energies that Connolly’s group was interested in—another million times more energetic—it was destined to fall short. 

Ultra-high-energy neutrinos are likely produced by cosmic ray bursts that are otherwise too difficult to see because their heavier components get bent by magnetic fields and everything but neutrinos gets bogged down in the celestial sludge left over from the early universe known as the cosmic microwave background. These neutrinos are extremely rare, and the volume of ice filled with IceCube detectors is too small to stand a reasonable chance of catching one. 

To increase the volume of detection, scientists turned to radio-wave detectors. The radio signal produced by neutrino explosions in ice is stronger for the highest-energy neutrinos, and it’s also able to travel much farther through ice without getting absorbed. So, fewer radio detectors can be placed larger distances apart to capture signals from a greater volume. In hopes of catching some ultra-high-energy neutrinos, scientists started building the Askaryan Radio Array (ARA), an array of radio detectors near the IceCube experiment, to detect neutrino events anywhere within 10 cubic kilometers of ice (compared to 1 cubic kilometer for IceCube). 

As a graduate student, Clark got his hands dirty with every aspect of the ARA experiment. He built two of the five radio detectors that were deployed and refurbished two more. He then went down to Antarctica, where he played a role in installing the detectors into the ice. 

“Antarctica was a really wild place,” Clark said. “It's constantly trying to kill you. But it's also a really beautiful place with a really unique community. It was great.”

After returning from Antarctica, Clark led the most comprehensive data analysis of ARA’s high-energy neutrino search to date. So far, they haven’t caught any of the elusive particles. But for this type of detector, they set the tightest limits on how many ultra-high-energy neutrinos could be hitting Earth. They developed efficient data analysis techniques that could be applied to a variety of detectors, operating over many years. 

“The detectors always look and behave a little bit differently, but you have to rely on all of them working together in order to do the science,” Clark said. “We demonstrated that you can do this kind of analysis at scale—that you can take data from detectors that look a little bit different, behave a little different and have been running for a long time.”

In addition to his hardware contributions, Clark also helped develop software that models neutrino interactions to aid in designing the next generation of detectors. In particular, he focused on how the signal from a neutrino explosion propagates through the ice. This is no easy task—the ice changes density from bottom to top, and the model needs to simulate millions of optical or radio signals traveling through it. Clark and his collaborators found and implemented an efficient way to model the curved trajectories the signals take, enabling the simulation to run in a reasonable timeframe. 

Clark’s mastery of all aspects of the ARA experiment, as well as his approachable nature, made him a valuable resource for junior members of the project and other collaborators. 

“One thing that’s really characteristic of Brian is what a fantastic mentor he is,” Connolly said. “He's always there to help, almost to a fault. I would always tell him, ‘Brian, you can point people to other places to get information.’ But everyone always wants to talk to Brian.”

After earning his Ph.D., Clark was awarded the prestigious NSF Astronomy and Astrophysics postdoctoral fellowship. He joined the physics and astronomy department of Michigan State University and brought the high-energy neutrino program there for the first time. 

“He was largely independent,” said Tyce DeYoung, one of Clark’s co-advisers at Michigan State and an associate professor of physics and astronomy. “He was sort of breaking new ground for the group here at Michigan State.

While there, Clark extended the search for ultra-high energy neutrinos to optical signals by finding new ways of analyzing data from IceCube. He also played key roles in planning the next generation of IceCube and a new neutrino-detection experiment being built in Greenland called the Radio Neutrino Observatory in Greenland (RNO-G), which has become part of his research focus at UMD. 

Throughout his graduate and postdoctoral career, Clark carried on his passion for community leadership and mentorship. As a graduate student, he helped design and facilitate Ohio State’s ASPIRE program, a hands-on physics research workshop for high school girls. He also brought physics demos to elementary schools and served for 18 months on his department’s Climate and Diversity Committee. As a postdoc, he was an early career scientist representative to the IceCube governance board and served on the IceCube collaboration’s working group on diversity and inclusion.

DeYoung appreciated Clark’s involvement with community building. 

“It was a great pleasure to work with him and to see him broaden his horizons while he was here, and to start to think about not just the scientific aspects of how you build a detector and how you analyze data, but also expanding to thinking about how you organize people to build these big projects and to operate these big projects,” DeYoung said. “How do you communicate with the scientific community and foster the sort of scientific community that we want?”

Now, Clark is looking forward to bringing his passions for the high-energy neutrino search and community building to UMD. 

“UMD is a really exciting nexus,” Clark said. “It's a really unique blend of experimental approaches, that makes it a unique place.”


Written by Dina Genkina