Year: 2025

Highlights from APS DPP

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Physics Faculty Attend Major Plasma Physics Conference in Atlanta

By Christopher Woolford, Physics PhD student

Over 200 faculty and students represented the University of Wisconsin–Madison at the annual American Physical Society Division of Plasma Physics (DPP) research conference in Atlanta last October. The APS DPP conference presents an excellent opportunity to learn about the newest and cutting-edge research in plasma physics.

a man stands in front of a poster and give a thumbs-up sign
Prof. Rogerio Jorge presents at the APS DPP conference

Rogerio Jorge, an assistant professor of physics at UW–Madison, presented his work on stellarator optimization alongside several of his students. Stellarators are a type of nuclear fusion reactor that uses twisted magnetic fields to confine fusion reactions.

“The weather was amazing, and the conference is a great opportunity for collaborations,” Jorge says.

This year, the APS DPP conference benefited from attendance by a new generation of plasma physicists that has seemed to have grown in recent years.

“I had not seen so many younger plasma physicists in years at an APS DPP conference,” says Paul Terry, a professor of physics at UW–Madison, attributing the rise in attendance to the influx of private companies interested in nuclear fusion.

Eduardo Neto, a postdoc at UW–Madison working with Jorge, gave a talk on his exciting work on Stellarator optimization. This work was the result of an ongoing collaboration with Proxima Fusion and IST in Lisbon, Portugal.

a man stands to the left of the picture in front of a screen. He is showing a powerpoint presentation to an audience of several dozen people
Eduardo Neto delivers an oral presentation at APS DPP in October.

“The most challenging part of this project was getting a lot of different codes to work together,” Neto says. “Startup companies have a strong interest in preventing tungsten buildup in Stellarators.”

Neto plans to continue his collaborations with Proxima Fusion and explore optimizing other parts of Stellarators such as turbulence. His advice for students interested in Stellarator optimization is to gain broad knowledge of plasma physics and nuclear fusion.

The APS DPP conference will be in November this year in Long Beach, California.

a smiling person stands in front of their scientific poster
Cameron Kuchta presents a poster at APS DPP.
two people stand in front of their scientific poster
Tony Qian and Jonathan Pizzo present a poster at APS DPP.
a man stands in front of a scientific poster
Djin Patch presents a poster at APS DPP.

Probing the connection between the highest-energy astrophysical neutrinos and ultra-high-energy cosmic rays

Neutrinos are weakly interacting particles that are able to travel undeflected through the cosmos. The IceCube Neutrino Observatory and the KM3NeT Astroparticle Research with Cosmics in the Abyss (ARCA) telescope (still under construction) are cubic-kilometer-scale neutrino telescopes that search for the sources of these astrophysical neutrinos in hopes of uncovering the origin of ultra-high-energy cosmic [...]

Read the full article at: https://wipac.wisc.edu/probing-the-connection-between-the-highest-energy-astrophysical-neutrinos-and-ultra-high-energy-cosmic-rays/

Welcome, Prof. Jakob Moritz!

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String theorist Jakob Moritz joined the faculty as an assistant professor of physics on January 1, 2025. He joins us from CERN where he has been a postdoc for just over a year. Previously, he was a postdoc for four years at Cornell University, and before that, he earned his PhD from the University of Hamburg and DESY.

Please give a general overview of your research.

I work on string theory, a theoretical framework for quantum gravity. It is the only known approach that consistently combines quantum mechanics and Einstein’s theory of gravity. Physicists have struggled for decades to reconcile these two fundamental theories, and string theory achieves this unification. Sometimes called “the theory of everything,” string theory addresses physical phenomena at arbitrarily high energies. While the nickname may sound a bit grandiose, it highlights the theory’s incredible scope.

However, while the field equations of string theory have solutions that are relatively easy to study, these don’t resemble our universe. My research focuses on going beyond these “easy” solutions to find ones that better match the universe we observe. By doing so, I aim to uncover insights into the origins of the peculiar laws of physics governing our universe.

Something that I find particularly interesting is dimensionless constants of nature. These constants are significant because they are independent of a choice of units. For example, the ratio of the electron’s mass to the top quark’s mass is a dimensionless number — about 0.000003, which is remarkably small! There are many such constants whose values are determined experimentally, yet we lack a theoretical explanation for them.

In the early 20th century, particle physicists didn’t focus much on questions like, “Why are the constants of nature what they are, and not something else?” But with string theory, we can begin to address this. My work seeks to identify solutions of string theory in which these numbers align with experimental values. Another well-known example is the energy density of the vacuum, or dark energy. Despite being the dominant energy source in the universe today, dark energy is extraordinarily small in natural units — just 10^{-120} when compared to the natural energy scale of quantum gravity. This discrepancy, known as the cosmological constant problem, is something I find deeply intriguing. How can such a small value arise? Why isn’t it zero? Similarly, why is the Higgs mass so small? These are the kinds of profound questions I aim to explore through string theory.

What are one or two main projects you’ll have new group members work on?

One major project will involve finding the Standard Model of particle physics within string theory. This is something I am already working on, but having more hands on deck would be invaluable. The goal is to “engineer” realistic laws of particle physics — either the Standard Model or something close to it — as solutions of string theory. This work is crucial for addressing the electroweak hierarchy problem: why is the Higgs mass so unnaturally small? Currently, no one has a clear explanation for this.

Technically, this involves a lot of geometry. String theory predicts the existence of extra dimensions, which are both a blessing and a curse. They must be small enough to have remained unobservable, yet they also determine the physical laws we experience at larger scales. Much of our work will focus on understanding these geometries — particularly how certain objects, called branes, wrap around features like circles in these spaces — and calculating the resulting physical laws.

What attracted you to Madison and the university?

I really appreciate the breadth of the theory department here. String theory is a vast field, encompassing topics that range from almost pure mathematics to particle phenomenology. Because my work leans toward the phenomenological side, it intersects with many other areas of theoretical physics, including cosmology, particle physics, and applied mathematics. Being at a large place like Madison, with its diverse and talented faculty, is incredibly exciting.

Additionally, I know that Madison attracts outstanding students who are eager to work on string theory and particle physics. That’s something I’m looking forward to as well!

What is your favorite element and or elementary particle?

Neutrinos are cool because they’re almost massless. For a long time, they were thought to have zero mass, as predicted by the Standard Model of particle physics. But experiment has revealed otherwise! This discovery hints strongly at new physics at high energies.

What hobbies and interests do you have?

I love music! I play piano and guitar, and music is a big part of my life, especially since my partner is also a musician. I also enjoy sailing. While at Cornell, I spent summers sailing and participated in weekly competitive races, which were incredibly fun. I know that sailing is also a thing here — I look forward to getting back on the water!

Baha Balantekin honored at neutrino astrophysics workshop

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a group of around 40 people stand on a wide staircase. The text says "Neutrinos in Physics and Astrophysics, 16-18 January 2025, Berkeley, CA. A workshop celebrating the contributions of Baha Balantekin and George Fuller"

The illustrious career of Baha Balantekin, the Eugene P. Wigner professor of physics at UW–Madison, was celebrated recently at the Neutrinos in Physics and Astrophysics Workshop through the Network for Neutrinos, Nuclear Astrophysics, and Symmetries (N3AS) Physics Frontier Center. 

Balantekin works at the intersection of nuclear physics, particle physics, and astrophysics. For much of his career, he has studied theoretical aspects of neutrinos originating in the Sun, supernovae, or neutron star mergers. He has helped pioneer the field known as neutrino astronomy.

three men pose standing next to each other
John Beacom, PhD ’97 (left), Baha Balantekin and George Fuller at the 2025 Neutrinos in Physics and Astrophysics workshop. (Provided by Rebecca Singh and Sarah Wittmer, UC Berkeley)

“Even just a few decades ago, if you said ‘neutrino astronomy,’ most physicists would have snickered. That’s because astronomy is about observations and neutrinos are almost impossible to detect,” says John Beacom, PhD ’97, distinguished professor of physics and astronomy at the Ohio State University. “But, over time, physicists have helped to make this seemingly impossible field into something real and vibrant. The observations of astrophysical neutrinos that have been made have been essential to understanding our Sun, supernovae, and distant galaxies.”

Balantekin and George Fuller, a distinguished professor of physics at the University of California, San Diego, have helped lead the field of neutrino astrophysics through both their scientific work and their mentoring of junior scientists. To honor both scientists’ significant and ongoing contributions to the field, three of their former students organized the workshop: Beacom, a former student of Balantekin’s, and Fuller’s former students Gail McLaughlin, distinguished university professor of physics at North Carolina State University and Yong Zhong Qian, professor of physics and astronomy at the University of Minnesota. The event was held Jan 16-18 at the University of California, Berkeley.

a man is presenting powerpoint slides to a small audience
Francis Halzen presents at the workshop. (Provided by Pupa Gilbert)

Francis Halzen, a current colleague of Balantekin’s at UW–Madison, was one of the speakers. Other attendees included UW–Madison physics professor Pupa Gilbert and professor emerit Sue Coppersmith. 

John Beacom and Pupa Gilbert contributed significantly to this story 

 

 

Dan McCammon awarded Distinguished Career Prize

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profile photo of Dan McCammon
Dan McCammon

Congrats to Prof. Dan McCammon for earning the Distinguished Career Award from The American Astronomical Society’s (AAS) High Energy Astrophysics Division (HEAD) for his pioneering work on the development of microcalorimeters that has led to breakthroughs in X-ray astronomy and on soft diffuse X-ray background.

The HEAD Distinguished Career Prize is awarded at the time of the Division Meeting to recognize an individual high-energy astrophysicist who has made outstanding contributions to the field of high energy astrophysics throughout their career. Outstanding contributions include a body of important research results (observational, theoretical or experimental) which have led to ground-breaking results in high-energy astrophysics, and/or a career of mentorship to a new generation of high-energy astrophysicists, especially if this mentorship helped to support under-represented or under-resourced scientists and increased the diversity of the HEA community. The winner gives an invited talk at the Divisional Meeting in the award year. The prize carries a cash award of $1500.

AAS announced many 2025 prizes today; the full list can be found at their website.

This post is adapted from the AAS news release and website linked within the text.