News - UMD Physics

From Physics to Pharma

Details: Category: Department News; Published: Tuesday, January 31 2023 00:01

Sylvie Ryckebusch (B.S. ’87, physics; B.S. ’87, mathematics) has never underestimated the value—or the challenges—of earning a physics degree.

“I think physics is the hardest subject really,” she explained. “It trains your problem-solving skills, the way you think and learning to work on difficult things. When you’ve spent years studying physics, I think it trains you well for many other lines of work.”Sylvie Ryckebusch

Ryckebusch applied these skills on a rewarding academic and professional path that took her from the research lab to the business world, and from the U.S. to Europe and beyond. Over the past 20 years, she built an impressive track record leading business development for biotech and pharmaceutical companies, negotiating complex research collaborations and licensing transactions, and specializing in everything from partnerships and corporate strategy to helping bring new therapeutics to market.

Today, as chief business officer at BioInvent International in Lund, Sweden, Ryckebusch supports the company’s efforts to develop new antibody drugs for the treatment of cancer. And though she didn’t exactly plan it this way, she’s exactly where she wants to be.

“People always ask me, ‘How did you organize your career to end up in business development?’ because that’s a place where a lot of people want to be—in the pharma industry, and most particularly, in business development” she said. “Honestly it was mostly happenstance. One thing led to another and another and I ended up here, although what was important in making these career choices was the self-awareness along the way about what kind of work and environment I enjoyed.”

European roots and a strong work ethic

Growing up in Howard County, Maryland, Ryckebusch always felt a strong connection to her European roots. Her parents immigrated to the U.S. from France before she was born.

“My mother was a secretary at the World Bank and my father was a chef,” she explained. “He grew up during the war in very difficult times in northern France and had to be pulled out of school early to help support the family, so he became an apprentice in a restaurant. When I was growing up, he was working around the Washington area as a chef and had his own restaurant for a time in Ellicott City.”

With many of her relatives still living in France, Ryckebusch decided to spend her high school years there. Fluent in French, she was interested in many subjects, but her teachers pushed her to pursue her strengths in mathematics.

“If you’re good at science, people aren’t going to tell you that you should study English literature,” Ryckebusch said. “I was always good at math and science and in the schools in France, if you’re good in math they tell you that’s what you’ve got to do, they push you.”

Ryckebusch returned to the U.S. after high school and began college at the University of Maryland in 1983, taking on the challenges of a double degree in mathematics and physics. Raised with a strong work ethic, she was driven to keep doing more.

“I made it really hard for myself,” she admitted. “I skipped the first-year courses, which I probably shouldn’t have done and I did a double-degree program, which would have been a five-year program, but I did it in four years. So, what I remember most from my UMD time is working really hard.”

In those intense academic years, Ryckebusch spent her summers working with a low-temperature physics group at Bell Labs. After graduating from UMD in 1987, she moved on to a Ph.D. program in computation and neural systems at Caltech.

“My focus was understanding the control of locomotion by the neural system,” she explained. “I was, on the one side, building integrated circuits, transistors and capacitors, the circuits that modeled certain behaviors of neurons in the brain, and in parallel, I was doing actual experiments to identify neuronal circuits involved in locomotor functions.”

After earning her Ph.D. in 1994, and a postdoctoral fellowship at Brandeis University, Ryckebusch was ready for something new.

“I had to weigh doing academic science for a career or at least the next six or seven years or starting something different, and I thought, I want a change,” she explained. “I like variety and I wanted to be in the real world, though I wasn’t really sure what the real world was.”

Encouraged by a friend, Ryckebusch joined the Harvard Business School as a postdoctoral researcher. There, she investigated business operations, developing case studies on companies all over the world, some of which are still taught at HBS today.

“I went to Japan, to Israel, all over the place, exploring particular issues related to businesses and the organization of their work and writing these up in case studies,” she recalled. “It was different and it was fun, and I fell into it very easily.”

From case studies to consulting

In 1996, Ryckebusch’s academic background, business research at Harvard and fluency in French helped her land a management consulting position at the Paris office of global consultants McKinsey & Company. The experience helped strengthen her skill set in corporate strategy and business development, but after four years, she realized she missed working with scientists and the intricacies of scientific problem-solving.

“I thought this has been fun and I learned so much, but it was very hard work and not really who I was” Ryckebusch explained. “I wanted to get back into a career closer to science.”

Hoping to apply her experience in both science and business, Ryckebusch joined Serono, a large Geneva, Switzerland-based biotech firm. She quickly realized it was the right place at the right time.

“I ended up in the very best possible place for me and I loved it,” she recalled. “You’re negotiating partnerships and alliances—pharma-pharma, pharma-biotech, biotech-academia alliances—and you have to have a good grasp of the science because you’re working on drug development. It was a business role that I’m still doing today over 20 years later.”

Pharmaceutical giant Merck eventually acquired Serono and shut down its Geneva office, but by then Ryckebusch had three kids in school and didn’t want to uproot her family. So, in 2012, she started her own consulting business. Based in Geneva, she worked with pharma and biotech clients, even finding time to teach a graduate-level pharmaceutical business development course at the Grenoble Ecole de Management.

Then in early 2020, one of Ryckebusch’s clients, BioInvent, suggested that she join them full time as chief business officer.

“BioInvent is a super company, with very high quality science and promising therapeutic drug candidates. I was doing more and more work with them, and they said, ‘Why don’t you join us,’ and it just made sense,” Ryckebusch recalled. “So that’s what I’m doing now.”

Part of a bigger mission

As BioInvent’s chief business officer, Ryckebusch works remotely from her home in Geneva, leading business development efforts, building partnerships and research collaborations for drug development, as well as supporting the investor-backed company with financing and company strategy.

“It costs $800 or $900 million to develop a pharmaceutical product, so biotechs almost never take them to market on their own, you have to partner with a big pharma at some point,” she explained. “There’s a whole strategy around how you partner, when you partner and with whom.”

Ryckebusch takes pride in her role as part of BioInvent’s scientific work in cancer therapeutics. But she’s quick to note that she’s just one small part of a much bigger mission.

“I enjoy that feeling of collectively bringing something forward—we’re all cogs in a wheel,” she explained. “In the pharma industry, it takes 15 to 20 years to develop a drug and a lot of people like me contribute along the way.”

For Ryckebusch, making that kind of contribution means everything.

“It’s all about finding great drugs and developing them and pushing the frontiers of the science,” she reflected. “I really hope one of BioInvent’s products makes it to the market. I would be proud to be able to say a little bit of that came from me.”

Recent Alumnus Embraced Community and Service at UMD

Details: Category: Department News; Published: Tuesday, January 31 2023 00:01

Joining a graduate program is not just about choosing a university and studying a subject. It’s also about joining a community of people who help shape the experience and can support and welcome people who are new to the world of academic research.

Andrew Guo (Ph.D. ’22, physics) spent a lot of his time at UMD researching the underpinnings of quantum interactions and algorithms as a graduate student at the Joint Quantum Institute and the Joint Center for Quantum Information and Computer Science (QuICS). During that period he also made time to connect with surrounding communities and to invite other people to participate in physics and astronomy research through the graduate student organization called Graduate Resources for Advancing Diversity with Maryland Astronomy and Physics (GRAD-MAP).

Andrew Guo teaching a lesson as part of the 2018 ASDAN Math Tournament in Beijing, China.Guo credits his choice to study physics to a natural spark of curiosity, along with his childhood enjoyment of math and science.

“Physics in particular inspired me, both because of its elegance and simplicity and its ability to have a huge impact on society,” Guo said. “For me, personal curiosity was a big factor. But also, knowing that there's potential societal impact as a result of research was a key motivating factor.”

Before coming to UMD, Guo studied physics as an undergraduate at Stanford University, where he became particularly intrigued by quantum information and quantum computing.

“I thought UMD was doing great work at that area from sort of the full stack—from experimental trapped ion quantum computing all the way up to the theoretical complexity theory side,” Guo said. “So, I wanted to dive in, and they offered me a fellowship through QuICS, which I've been affiliated with through all my six plus years here. And I think I found a great community there.”

Andrew Guo with three other recipients of QuICS Lanczos Graduate Fellowships. From left to right: Aniruddha Bapat, Minh Tran, Andrew Guo, and Eddie Schoute. Image credit: Arushi Bodas

After Guo decided to come to UMD, he hadn’t settled on exactly what aspects of quantum research to focus on, and there were several professors he was open to working with. Alexey Gorshkov, an adjunct associate professor of physics at UMD, approached him about research into long-range interacting systems. This research looked at how interactions between quantum particles that aren’t immediate neighbors influence the spread of the property called quantum entanglement and can speed up quantum computations.

“I was excited that I was able to get such an outstanding student,” Gorshkov said. “It was fantastic, from both the research aspect and the mentoring service aspect. He did well in both, wrote excellent papers, and also was very helpful to other people in the group.”

Pursuing the line of research, Guo and his colleagues were able to make several advances, including identifying how speed limits for quantum information can depend on the particular task and making a protocol that achieves the theoretical speed limit for certain tasks.

“I found it very, very helpful to have close collaborators—people to talk to who can help you when you're stuck, who can bounce ideas off each other,” Guo said. “It was a pleasant surprise to find that the collaborative environment at Maryland was such an integral part of grad school.”

While beginning graduate research, Guo also wanted to do community outreach. Guo learned about GRAD-MAP during his first year at UMD, when one of the organization’s leaders gave a presentation to the physics graduate students. GRAD-MAP is dedicated to promoting diversity, equity and inclusion in the fields of physics and astronomy. The organization strongly focuses on reaching out to students with backgrounds that are underrepresented in physics and astronomy and bringing them to UMD to share valuable experiences in the field.

“We are grad students working to promote inclusive environments for fellow grad students, as well as increase the proportion of students who come from underrepresented minority backgrounds,” Guo said.

GRAD-MAP organizes programs to give undergraduate students insight into the world of physics and astronomy research and help them develop useful skills. The organization runs a weeklong Winter Workshop where undergraduates tour scientific facilities, perform mini-research projects and develop skills, such as writing application essays and computer programing. GRAD-MAP also organizes a 10-weeks-long Summer Scholars Program where undergraduate students can build on the Winter Workshop skills with a full research project under the supervision of a mentor. GRAD-MAP has worked with students from nearby institutions like Prince George’s Community College, Montgomery College and Howard University, as well as students from across the U.S. and outside the country.

Guo’s first January at UMD, he taught the programming language Python at the Winter Workshop. He said he was inspired by the students and kept teaching programing as part of GRAD-MAP. He eventually worked his way up to leading the entire Python portion of the workshop.

“For these students to learn programming, I think is pretty significant because it gives them a playground to test their ideas,” Guo said. “And it's very good practical training for them, regardless of what career they pursue in the future, be it physics or astronomy grad school or even a career as a software engineer.”

In the fall of 2019, he became the physics co-lead of GRAD-MAP. Then, in the face of the coronavirus pandemic, he had to pivot the program. The GRAD-MAP graduate students transitioned their outreach events online for their 2020 and 2021 Winter Workshops and 2020 Summer Scholars Program.

“A lot of credit goes to my fellow graduate colleagues who really stepped up,” Guo said. “The biggest challenge was to replicate that sense of community online, without leading to basically Zoom fatigue and burnout among the students. I think the students really were the ones who put in the most heroic effort—just going through enduring and then sticking with us as we performed this huge experiment that everybody was doing at that time.”

Andrew Guo and his co-leads Milena Crnogorčević and Charlotte Ward on a video chat with five participants of the 2021 Summer Scholars Program. Despite the additional stress, Guo fondly recalled a GRAD-MAP video chat event where the Winter Workshop participants could show off talents, like playing an instrument, or share other things they cared about, like a participant discussing their plant terrarium. Guo said seeing both the engagement and lasting impact on the students from the program was very fulfilling.

During his time at UMD, Guo also joined communities outside of GRAD-MAP and his lab group. Throughout his time at UMD he lived with other physicists.

“It was definitely a uniquely collaborative, uniquely enriching experience for me,” Guo said. “Throughout COVID not being able to see your coworkers in person made this all the more valuable because you could have informal conversations.”

He also played the cello as a member of the UMD Repertoire Orchestra (now rebranded as the University Orchestra), which is open to members of the campus community, including students from non-music degree programs. He said participating in that creative expression was a nice pressure valve.

Next, Guo will be joint a new community at Sandia National Laboratories as a postdoctoral researcher and said he hopes to participate in outreach efforts there.

Story by Bailey Bedford

Nathan Schine Twists Photons and Cools Atoms in a Unique Quantum Dance

Details: Category: Department News; Published: Thursday, January 26 2023 00:01

Deepening our understanding of the quantum world and developing new tools to peer into it is a very active area of physics research today. In this crowded field full of diverse theoretical ideas and physical tools, Assistant Professor and JQI Fellow Nathan Schine has managed to carve out a distinctive space for himself and his lab.Nathan Schine

Schine’s research program manipulates the interactions between atoms and photons—the particles that make up light—in novel, well-controlled ways in order to simulate other, harder-to-probe quantum phenomena. To coax the photons into new simulation patterns, Schine is using unique arrangements of mirrors to bounce photons around. He is also strategically placing atoms in the photons’ way with the help of precisely controlled laser beams. To boot, the atoms he is using (ytterbium) have a relatively complex structure, giving Schine extra avenues to explore. He has been able to create this unique niche by combining the experimental expertise he gained from graduate school and postdoctoral research with his theoretical big-picture savvy.

Schine has been slowly homing in on his academic sweet spot for much of his life. Growing up, his interests were broad—they included science and math, but also history and other areas of the humanities. “It wasn't like I knew from an early age that I was going to go be a physicist,” Schine says.

Science wasn’t outside the realm of Schine’s imagination, however. His father was a chemistry teacher, his mother had a degree in math, and his grandfather was a physics professor at Vanderbilt University.

Keeping his options open, Schine attended Williams College. Ranked first among U.S. liberal arts colleges by U.S. News and World Report, Williams boasts an unusually strong science and math program. Schine was interested in math, but eventually found it to be too abstract for his taste. “When math got into proving the existence of a solution to a problem and not actually solving the problem, I sort of lost the thread a bit,” he recalls. Instead, he found that the part of math he enjoyed most could be gotten through physics, so he dove deeper into the subject.

An undergraduate research project sealed the deal for Schine as a physicist and experimentalist. He started working in the lab of his soon-to-be quantum mechanics professor, Barclay Jermain Professor of Natural Philosophy at Williams Protik Majumder, midway through his sophomore year.

Under Majumder’s supervision, Schine started to get a taste for experimental physics. He was performing spectroscopic measurements on indium atoms as a sophomore and continued working with Majumder until he graduated. Indium, with its three loosely bound, outermost electrons, is hard to model theoretically, and Majumder’s lab collaborated with theorists to benchmark their calculations and zero in on precise values.

Schine relished the chance to make a real contribution to the project. He also found joy in tinkering in the lab, finding his calling as an experimentalist. “I liked the day-to-day aspects of it, the actual process of building a laser or something,” Schine says. “A lot of it is very tactile and building up this sort of Rube Goldberg device that happens to be useful for physics—that, I think, is a lot of fun.”

Majumder had a slightly different take on what set Schine apart in his lab. “He was really unusual, even as a 20-year-old, in being able to balance comfortably the very hands-on build stuff with the bigger intellectual picture, which is obviously something that's been characteristic of his career since then,” Majumder says. Schine’s research with Majumder culminated in a senior thesis and a peer-reviewed publication.

Schine was inspired by his undergraduate research experience and decided to pursue graduate school. His chops setting up lasers and other experimental equipment meant he could hit the ground running and start contributing right away to the brand-new lab of Jonathan Simon at the University of Chicago.

The lab Simon was envisioning involved filling an optical cavity—a set of mirrors trapping light and bouncing it back and forth between them—with ultracold rubidium atoms. The idea was to use the photons themselves as a quantum playground, used to re-create and study quantum phenomena that happen in other, less accessible settings.

A lot of the interesting quantum phenomena that appear in real materials are hard to peer into at the quantum level but are nevertheless important for our daily lives because of their ubiquitous applications in technology. In Simon’s lab, precisely controlled photons can play a similar role to electrons inside of a material. Studying how these photons behave in a cavity and measuring them directly can then give clues about what happens inside the chunks of material.

There is one obvious limitation for photons playing the part of electrons: They don’t have an electric charge. And charged electrons—specifically in magnetic fields—are responsible for a range of interesting material effects that might need simulating.

Back in the early 1980s, physicists discovered one such effect. A thin layer of semiconductor placed inside a strong magnetic field was found to conduct electricity in very precise chunks. As the magnetic field is increased, the conductivity doesn’t change for a while—it stays at one plateau—and then hops abruptly to another plateau. This is known as the integer quantum Hall effect (IQHE) because the plateaus appeared at very regularly spaced integer values.

Even more strangely, for very cleanly engineered semiconductors, experimentalists found sub-plateaus within the plateaus, appearing at precise fractions of the previous integer values. They termed this, predictably, the fractional quantum Hall effect (FQHE). The origins of these fractional plateaus are largely still a mystery, although physicists are pretty certain that it has something to do with interactions between electrons giving rise to unexpected collective behaviors. If there was a way to simulate the full quantum theory of the FQHE, it might reveal new insights into what’s going on.

Simon and Schine, along with their labmates, hatched a plan. They conceived of a new way to make photons behave as though they have charge and live in a magnetic field that could, in principle, allow the photons to interact with each other and simulate the FQHE. Their plan involved a wonky cavity: four mirrors aligned to bounce light around in a twisted bow-tie configuration over and over again, with one of the mirrors slightly askew, as in the diagram shown below.

Photons and atoms in Schine’s tilted bow-tie cavity. (Credit: Nathan Schine/JQI)

Schine and his labmates focused on what happened along a plane at the center of this cavity. There, the photons were analogous to electrons traveling inside a thin material like in either of the Hall effects. The twisted mirror configuration causes the photons to twist around, much like electrons precess around inside a magnetic field.

With careful cavity design, they were able to make the analogy come to life and make their photons replicate the IQHE in its full glory. They published this result in the journal Nature.

To go beyond integer quantum Hall physics, the particles need to interact with one another—not just pass through each other, like photons are wont to do. That’s where atoms entered the picture. Previously, scientists had worked out a technique that allows atoms to serve as an intermediary through which photons can talk to each other.

In parallel with the twisted cavity work, Simon’s lab had been working on this atom-assisted approach to making photons interact with each other. This involved cooling a gas of rubidium atoms to extremely low temperatures, just a touch above absolute zero. Then, the light was tuned to a particular color that would allow one of the rubidium atoms to absorb a single photon. This atom then prevented any nearby atoms from absorbing a photon, ensuring no other photon got too close. This created an effective interaction between photons, where they were averse to being too close to one another.

The next step was to combine the two techniques: put the rubidium inside the skewed bowtie cavity. The cavity makes photons act like electrons in a magnetic field, and the atoms create a medium through which the photons can interact. The combination created the right conditions for FQHE physics. Although short-lived, the photons in Schine’s experiment appeared to indeed exhibit the hallmarks of fractional quantum Hall physics. Schine and his labmates published this result in the journal Nature.

This was the first time the fractional quantum Hall effect had been simulated in any medium. For his graduate work, Schine was named a finalist for a thesis prize from the American Physical Society’s Division of Atomic Molecular and Optical Physics, the most prestigious thesis award in this field.

Schine was still circling around his ultimate niche, though, and he sought to broaden his experimental skillset during his postdoctoral studies. He joined the group of Adam Kaufman at JILA at the University of Colorado Boulder (sometimes snarkily called JQI West). Kaufman’s lab manipulates atoms with light, using a tool called optical tweezers—laser beams focused down to a very narrow spot, intense enough to hold an atom in place.

Schine, Kaufman, and collaborators used these optical tweezers to put a new spin on atomic clocks, which are the most precise timekeepers we have. They work by counting the intrinsic ticking of individual atoms. Precise as they are, scientists are actively working on making them even more so, both for better technology like navigation and geolocation and for scientific inquiries, like the basic nature of fundamental constants and gravity.

The team endeavored to use a fundamentally quantum property—entanglement—to make pairs of atoms tick in tandem, thereby making the clock more precise. They cooled a gas of strontium atoms just above absolute zero and used optical tweezers to create a large array of atom pairs. These pairs were then made to interact using the same trick Schine had used during his graduate work: one atom absorbing a photon prevented another atom nearby from doing so as well, thus making their behavior depend on one another. Generating entangled atoms like this is a promising way to improve clock performance. They published this work in the journal Nature Physics.

Now, Schine is starting to build up his own lab here at the University of Maryland. When deciding exactly what kind of experiment to embark upon, Schine was guided by his graduate school advisor Simon’s philosophy. “There are different strategies for setting up experiments,” Schine says. “But I think Jon’s was very much to build something that no one else has done before experimentally—to put ourselves in an area where there's a lot of low-hanging fruit.” Schine explained that this will involve combining his optical cavity expertise with an array of tweezer-trapped atoms, now using ytterbium. For instance, he predicts this will allow dramatic improvements in performing quantum measurements, which is an essential part of quantum computing or quantum simulation experiments.

As Schine is assembling his lab and unique research program, he encourages interested students and postdocs to reach out to him. And, according to Schine’s undergraduate adviser, Schine’s teaching and mentoring abilities promise to be excellent. “One of the things we really work hard at in a place like Williams,” Majumder says, “is to make sure our students are not just the ones who can get into the lab, hide in a corner and just do amazing work. And that really comes through with Nathan. He's just such a good explainer of what he's doing. And he's so enthusiastic—it's very infectious.”

Story by Dina Genkina

UMD Physicists Hope to Strike Gold by Finding Dark Matter in an Old Mine

Details: Category: Research News; Published: Thursday, January 26 2023 00:01

Nestled in the mountains of western South Dakota is the little town of Lead, which bills itself as “quaint” and “rough around the edges.” Visitors driving past the hair salon or dog park may never guess that an unusual—even otherworldly—experiment is happening a mile below the surface.

A research team that includes University of Maryland physics faculty members and graduate students hopes to lure a hypothesized particle from outer space to the town’s Sanford Underground Research Facility, housed in a former gold mine that operated at the height of the 1870s gold rush.

More specifically, they are searching for WIMPs—weakly interacting massive particles which are thought to have formed when the universe was just a microsecond old. The research facility suits this type of search because the depth allows the absorption of cosmic rays, which would otherwise interfere with experiments.

If WIMPs are observed, they could hold clues to the nature of dark matter and structure of the universe, which remain some of the most perplexing problems in physics.

Just getting started
The UMD team is led by Physics Professor Carter Hall, who has been looking for dark matter for 15 years. Excited by the prospect of observing unexplained physical phenomena, Hall joined the Large Underground Xenon (LUX) experiment, an earlier instrument at the Sanford Lab that attempted to detect dark matter from 2012 to 2016.

LUX was the most sensitive WIMP dark matter detector in the world until 2018. Its successor at Sanford, the new and improved LUX-ZEPLIN (LZ) experiment, launched last year. Hall believes LZ has even better odds of detecting or ruling out dark matter due to its significantly larger target. It’s specifically designed to search for WIMPs—a strong candidate for dark matter that, if proven to exist, could help account for the missing 85% of the universe’s mass.

Unlike experiments conducted at particle smashers like the Large Hadron Collider (LHC) in Switzerland, the LZ attempts to directly observe—rather than manufacture—dark matter. Anwar Bhatti, a research professor in UMD’s Department of Physics, said there are pros and cons to both approaches. He worked at the LHC from 2005 to 2013 and is now part of the LZ team at UMD.

Bhatti said the odds of finding irrefutable proof of WIMPs are slim, but he hopes previously undiscovered particles will show up in their experiment, leaving a trail of clues in their wake.

“There’s a chance we will see hints of dark matter, but whether it’s conclusive remains to be seen,” Bhatti said.

UMD physics graduate students John Armstrong, Eli Mizrachi, and John Silk are also part of this experiment, and the team published its first set of results in July 2022 following a few months of data collection. No dark matter was detected, but their results show that the experiment is running smoothly. Researchers expect to continue collecting data for up to five years.

“That was just a little taste of the data,” Hall said. “It convinced us that the experiment is working well, and we were able to rule out certain types of WIMPs that had not been explored before. We’re currently the world’s most sensitive WIMP search.”

Sparks in the dark

These direct searches for dark matter can only be conducted underground because researchers need to eliminate surface-level cosmic radiation, which can muddle dark matter signals and make them easier to miss.

“Here, on the surface of the Earth, we’re constantly being bathed in cosmic particles that are raining down upon us. Some of them have come from across the galaxy and some of them have come across the universe,” Hall explained. “Our experiment is about a mile underground, and that mile of rock absorbs almost all of those conventional cosmic rays. That means that we can look for some exotic component which doesn’t interact very much and would not be absorbed by the rock.”

In the LZ experiment, bursts of light are produced by particle collisions. Researchers then work backward, using the characteristics of these flashes of light to determine the type of particle.

The UMD research group calibrates the instrument that powers the LZ experiment, which involves preparing and injecting tritium—a radioactive form of hydrogen—into a liquefied form of xenon, an extremely dense gas. Once mixed, the radioactive mixture is pumped throughout the instrument, which is where the particle collisions can be observed.

The researchers then analyze the mixture’s decay to determine how the instrument responds to background events that are not dark matter. By process of elimination, the researchers learn the types of interactions are—and aren’t—important.

“That tells us what dark matter does not look like, so what we’re going to be looking for in the dark matter search data are events that don’t fit that pattern,” Hall said.

The UMD team also built, and now operates, two mass spectrometry systems that monitor xenon to ensure it isn’t poisoned by impurities like krypton, a gas found in the atmosphere. To detect dark matter scatterings, xenon must be extremely pure with no more than 100 parts per quadrillion of krypton.

Rewriting the physics playbook

The researchers will not know if they found dark matter until their next data set is released. This could take at least a year because they want the sensitivity of the second data set to significantly exceed that of the first, which requires a larger amount of data overall.

If detected, these WIMP particles would prompt a massive overhaul of the Standard Model of particle physics, which explains the fundamental forces of the universe. While this experiment could answer pressing questions about the universe, there is a good chance it will also create new ones. Hall thinks up-and-coming physicists will welcome that challenge.

“It would mean that a lot of our basic ideas about the fundamental constituents of nature would need to be revised in one way or another,” Hall said. “Understanding how that would fit into particle physics as we know it would immediately become the big challenge for the next generation of particle physicists.”

Written by Emily Nunez

From Physics to Pharma

Recent Alumnus Embraced Community and Service at UMD

Nathan Schine Twists Photons and Cools Atoms in a Unique Quantum Dance

UMD Physicists Hope to Strike Gold by Finding Dark Matter in an Old Mine

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