IceCube

Four professors earn promotions, including tenure for Ke Fang

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Congratulations to Associate Professor Ke Fang on her promotion with tenure, to Professor Justin Vandenbroucke on his promotion to full professor, and to Profs. Dan Hooper and Britton Plourde who were both granted tenure!  

profile photo of Ke Fang
Ke Fang

Prof. Fang is an experimental particle astrophysicist and WIPAC investigator who studies the origins of subatomic particles and their fundamental nature by detecting messengers from throughout the universe. She has made major contributions to the analysis of data from the High Altitude Water Cherenkov (HAWC) Observatory, the IceCube Observatory and the NASA Fermi satellite. 

In 2021, Fang received the Shakti P. Duggal Award for Early Career Contributions in Cosmic Ray Physics. In 2023, she received the NSF CAREER award. In 2024, she was named a Sloan Fellow. Later that year, she was named the inaugural recipient of the Bernice Durand Faculty Fellowship, a departmental award named in honor of Durand, one of the first two women faculty members in the UW–Madison physics department. She also served as the US spokesperson for HAWC in 2023-2025. 

“Ke Fang is one of the most impactful astroparticle phenomenologists of her generation,” says physics department chair and professor Kevin Black. “Her work is highly original and broad with strong implications for the emerging area of multi-messenger astronomy and particle astrophysics.” 

profile photo of Justin Vandenbroucke
Justin Vandenbroucke

Prof. Vandenbroucke is also a WIPAC investigator and experimental particle astrophysicist. He joined the department in 2013. His main research focus is in multi-messenger astrophysics, including neutrino astronomy, gamma-ray astronomy, and cosmic rays. He is a member of the IceCube collaboration and the Cherenkov Telescope Array Observatory consortium and is an affiliate member of the Fermi LAT and VERITAS collaborations. 

Vandenbroucke was previously promoted to associate professor with tenure in 2019. He was named a Vilas Associate from 2023-2025, and was a co-recipient of UW2020 awards in 2018 and 2020. He also leads the Distributed Electronic Cosmic-Ray Observatory (DECO), a citizen science project that enables users around the world to detect cosmic rays and other energetic particles with their cell phones and tablets. 

“Justin Vandenbrouke is an outstanding experimentalist who, at the same time, develops creative and challenging data analysis projects that have led to scientific results published in highly cited papers,” Black says. “He does this in two different fields, gamma-ray and neutrino astrophysics, and is a leader in both.”

Profile photo of Dan Hooper
Dan Hooper

Prof. Hooper, PhD’03 was named the director of WIPAC and joined the physics faculty as a full professor in 2024. He is a theoretical particle astrophysicist whose research focuses on the interface between particle physics and cosmology. His work has spanned the areas of dark matter, high-energy neutrino astronomy, gamma-ray astronomy and cosmic-rays. He is the author of several books and co- hosts the physics podcast “Why This Universe?” breaking down some of some of the biggest ideas in physics into easily digestible chunks.

“Dan Hooper is a singular figure in his field, a stand-out leader in terms of scientific impact whose ideas cast a wide influence on the study of high energy theory, dark matter phenomenology, collider physics, astroparticle physics, and the direct experimental and observational search for dark matter,” Black says. 

profile photo of Britton Plourde
Britton Plourde

Prof. Plourde joined the department as a full professor in 2024 from Syracuse University. He is an experimental condensed matter physicist who studies superconducting quantum circuits. He is currently on a half-time leave at UW–Madison and works with Qolab, a quantum computing startup company based in Madison. Plourde was elected a Fellow of the American Physical Society in 2024 in the Division of Quantum Information, and in 2023 was elevated to Fellow of the Institute of Electrical and Electronics Engineers. 

“Britton Plourde is internationally recognized for his contributions in the field of low-temperature physics and superconducting quantum circuits,” Black says. “He has made significant contributions in the field of superconducting quantum computing and is best known in the community for his works on superconducting qubits, left-handed and quantum metamaterials, and, more recently, for studies of decoherence sources and suppression of errors in superconducting quantum circuits.”

Natasha Kassulke and Alisa King-Klemperer contributed to this story

 

Ke Fang named inaugural recipient of the Bernice Durand Faculty Fellowship

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The Department of Physics is pleased to announce that Ke Fang, assistant professor of physics and WIPAC investigator, has received the inaugural Bernice Durand Faculty Fellowship. This fellowship, given in honor of late Professor Emerit of Physics Bernice Durand, recognizes Fang’s major contributions to the analysis of data from the NASA Fermi satellite, the High Altitude Water Cherenkov (HAWC) telescope and IceCube, and for fundamental theoretical insights in their multimessenger context. Fang is a Sloan Fellow, has been awarded an NSF CAREER award, and is the spokesperson for the HAWC experiment.

a man and a woman smile while both holding a framed award certificate
Department Chair and professor Mark Eriksson (left) presents assistant professor Ke Fang with the Bernice Durand Faculty Fellowship at the department awards banquet in May 2024.

Durand was one of the first two women professors in the UW–Madison Department of Physics. While at UW–Madison, Durand was a theoretical physicist who specialized in particle theory and mathematical physics. Her research was on symmetry relations in algebra and physics, plus the phenomenology of high-energy interactions at large particle accelerators.

As the first Associate Vice Chancellor for Diversity & Climate, Professor Durand provided leadership to ensure that faculty, staff, and student diversity issues including race, ethnicity, gender, sexual preference, and classroom and general campus workplace climate issues be addressed, and that search committees for non-classified staff be trained in broadening the pool of applicants and eliminating implicit bias. Durand co-directed a grant from the Alfred P. Sloan Foundation to the UW System designed to create more equity, flexibility and career options for faculty and academic staff. She was also a member of the leadership team of the Women in Science and Engineering Leadership Institute sponsored by the National Science Foundation to increase the participation and status of women in science.

A recipient of the Chancellor’s Award for Outstanding Teaching, Professor Durand taught courses at all levels, from modern physics for non-scientists (“Physics for Poets”) to a specialized course she developed for advanced graduate students in the use of topology and algebra in quantum field theory. In the mid 1990s, she used technological and pedagogical techniques in her teaching, such as broadcasting her modern physics for non-scientists course on public television with web-based coursework, and pioneering one of two early versions of MOOCs (massive open online courses) on campus.

Durand passed away in 2022.

The Bernice Durand Faculty Fellowship was conceived by our Board of Visitors, who spearheaded the ultimately-successful fundraising effort, with support from Professor Emerit Randy Durand for this fellowship honoring his wife.

Ke Fang named Sloan Fellow

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This story is adapted from one published by University Communications

profile photo of Ke Fang
Ke Fang

Ke Fang, assistant professor of Physics and WIPAC investigator, is among 126 scientists across the United States and Canada selected as Sloan Research Fellows.

The fellowships, awarded annually since 1955, honor exceptional scientists whose creativity, innovation and research accomplishments make them stand out as future leaders in their fields.

Using data from the Ice Cube Observatory and Fermi Large Area Telescope along with numerical simulations, Fang studies the origin of subatomic particles — like neutrinos — that reach Earth from across the universe.

“Sloan Research Fellowships are extraordinarily competitive awards involving the nominations of the most inventive and impactful early-career scientists across the U.S. and Canada,” says Adam F. Falk, president of the Alfred P. Sloan Foundation. “We look forward to seeing how fellows take leading roles shaping the research agenda within their respective fields.”

Founded in 1934, the Sloan Foundation is a not-for-profit institution dedicated to improving the welfare of all through the advancement of scientific knowledge.

Sloan Fellows are chosen in seven fields — chemistry, computer science, Earth system science, economics, mathematics, neuroscience and physics — based on nomination and consideration by fellow scientists. The 2024 cohort comes from 53 institutions and a field that included more than 1,000 nominees. Winners receive a two-year, $75,000 fellowship that can be used flexibly to advance their research.

Among current and former Sloan Fellows, 57 have won a Nobel Prize, 71 have been awarded the National Medal of Science, 17 have won the Fields Medal in mathematics and 23 have won the John Bates Clark Medal in economics.

Xiangyao Yu, assistant professor of computer sciences at UW–Madison, was also named a Sloan Fellow.

 

First field season for IceCube Upgrade ongoing at the South Pole

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Over the past two months, a team of IceCube drill engineers have completed an impressive amount of work during the first of three consecutive field seasons for the IceCube Upgrade. The project is funded by the National Science Foundation and international collaborators.

The goal of the project is to drill seven holes in 2025/2026 and deploy seven more closely spaced and more densely instrumented strings of sensors in the central part of the array, which will improve IceCube’s sensitivity to low energies. Having a productive first field season both sets the Upgrade project up for success and trains the new generation of drillers at the South Pole.

The majority of the team’s engineers come from the University of Wisconsin–Madison’s Physical Sciences Laboratory (PSL), where equipment is fabricated and shipped to the South Pole. Additional drill engineers hail from Sweden, New Zealand, and for the first time, Thailand.

“This year’s drill team is a group of 17 talented professionals who have completed an enormous amount of work,” says Kurt Studt, drill engineer at PSL and the on-ice drill manager for the Upgrade. “We’ve overcome many difficult challenges while dealing with the extreme environment at the South Pole, including temperatures as low as -35 ⁰F and windchills below -60 ⁰F.”

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a metal coiled cone on the left, and the hole it drilled in Antarctic ice on the right
The IFD “carrot” drill head (left) drills a 40-meter hole in the firn (right). Credit: Kurt Studt, IceCube/NSF

Lu Lu receives 2023 IUPAP Early Career Scientist Prize

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This story was originally posted by WIPAC

IceCube collaborator and UW–Madison assistant professor of physics Lu Lu received a 2023 International Union of Pure and Applied Physics (IUPAP) Early Career Scientist Prize “for her contributions to the development of high energy neutrino astronomy in the PeV energy region.” Lu accepted the award on July 27 during the opening ceremony at the 38th International Cosmic Ray Conference (ICRC) held in Nagoya, Japan.

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Lu Lu

Early Career Scientist Prizes are given to early career scientists within each IUPAP commission who have up to eight years of postdoctoral research experience and have made significant contributions to the cosmic ray field. Lu is a recipient of the Early Career Scientist Prize in the Commission on Astroparticle Physics (C4).

Her PhD work focused on developing a novel technique to search for ultra-high-energy photons using data from the Pierre Auger Observatory. She also played a leading role in the initial design of the “Dual optical sensors in an Ellipsoid Glass for Gen2” (D-Egg), a two-PMT optical module for the IceCube Upgrade.

More recently, she made key contributions to the multimessenger correlation studies of the neutrino source candidate TXS0506+056 and to the detection of a particle shower associated with the hadronic decay of a resonant W boson.

Lu is currently an assistant professor of physics at the Wisconsin IceCube Particle Astrophysics Center (WIPAC) at the University of Wisconsin–Madison. Her current research focuses on diffuse high-energy astrophysical/cosmogenic neutrinos from TeV to EeV, Galactic PeVatron detection in the context of multimessenger observations, and the exploration of potential transient ultra-high-energy sources.

She is actively involved in IceCube outreach initiatives and has pioneered the development of an app that provides IceCube real-time alerts via augmented reality on mobile devices. Currently, she serves as co-lead of the diffuse science working group in IceCube and is one of three representatives of the physical science group of US-SCAR (Scientific Committee of Antarctic Research).

“I would like to express my deep appreciation for my collaborators and for those who work on foundational tasks such as reconstructions and calibrations, as their efforts behind the scenes make groundbreaking discoveries possible,” said Lu. “As early career scientists, we bear the responsibility of continuing and expanding experiments in the particle astrophysics field. We must collaborate and work together to ensure that the next generation of young scientists will have exciting discoveries to make.”

IceCube shows Milky Way galaxy is a neutrino desert

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a red-lit IceCube lab (a metal modern-looking lab building stationed at the south pole) with the white swirl of the Milky Way behind it is in a photo, with an artists rendering of a stream of neutrinos (greek letter nu) streams out of the center of the Milky Way

The Milky Way galaxy is an awe-inspiring feature of the night sky, dominating all wavelengths of light and viewable with the naked eye as a hazy band of stars stretching from horizon to horizon. Now,

In a June 30 article in the journal Science, the IceCube Collaboration — an international group of more than 350 scientists — presents this new evidence of high-energy neutrino emission from the Milky Way. The findings indicate that the Milky Way produces far fewer neutrinos than the average distant galaxies.

“What’s intriguing is that, unlike the case for light of any wavelength, in neutrinos, the universe outshines the nearby sources in our own galaxy,” says Francis Halzen, a professor of physics at the University of Wisconsin–Madison and principal investigator at IceCube.

The IceCube search focused on the southern sky, where the bulk of neutrino emission from the galactic plane is expected near the center of the galaxy. However, until now, a background of neutrinos and other particles produced by cosmic-ray interactions with the Earth’s atmosphere made it difficult to parse out neutrinos originating from galactic sources — a significant challenge compounded by relatively sparse neutrino production in general.

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Ke Fang earns NSF CAREER award

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Ke Fang

Congrats to Ke Fang, assistant professor of physics, WIPAC faculty member, and HAWC spokesperson, on earning an NSF CAREER award! CAREER awards are NSF’s most prestigious awards in support of early-career faculty who have the potential to serve as academic role models in research and education and to lead advances in the mission of their department or organization.

Fang’s award is sponsored by the NSF Windows on the Universe: Multimessenger Astrophysics program. In multimessenger astrophysics, scientists search for multiple high energy signals to identify their sources and learn more about the makeup of our universe. WIPAC hosts both the IceCube neutrino telescope and the HAWC gamma ray telescope, and Fang says she is excited to have access to high-quality data from both. In her NSF proposal, she plans to use that data in two ways.

“One is evolving novel data analysis techniques to study the problems that remain outstanding, such as the source of high-energy neutrinos,” Fang says. “The second part is once we have these data analysis results, then we’ll use numerical simulations to understand our observations.”

In addition to an innovative research component, NSF proposals require that the research has broader societal impacts, such as working toward greater inclusion in STEM or increasing public understanding of science. Once again, Fang finds herself well-positioned at WIPAC, where the outreach team has developed Master Classes, a one-day event where high school students come to WIPAC, spend time with scientists, and learn about topics not typically covered in high school physics class. Currently, the students learn about IceCube’s instrumentation and how to analyze the complex detector data.

“The course is already well designed, but from my perspective, I use a lot of numerical simulation in my research, so one thing I proposed to do is that I would design a module that would incorporate some of these modern numerical study techniques into the master class,” Fang says. “The students will now learn how to study physics using supercomputers, using numerical simulations.”

Help IceCube decode signals from outer space in new Citizen Science project

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Every second, about 100 trillion neutrinos pass through your body unnoticed. At the South Pole, the IceCube Neutrino Observatory detects these elusive particles and works to identify their astronomical origins to help unlock mysteries of the universe. Such an undertaking requires a massive amount of data, with one terabyte of data recorded daily by IceCube. But organizing the data can be labor intensive. This is where the public can help.

Starting today, volunteers from anywhere can participate in the Name that Neutrino project led by IceCube researchers at Drexel University, which asks users to categorize IceCube data. Through the Zooniverse platform, volunteers can join in from the convenience of their own computer or phone. Name that Neutrino is open to everyone and will run for about 10 weeks.

Read the full story at https://icecube.wisc.edu/news/2023/03/help-icecube-decode-signals-from-outer-space/

Want to get involved? Here’s how:

  1. Click on the link: https://www.zooniverse.org/projects/icecubeobservatory/name-that-neutrino 
  2. Click “Get Started” to begin.
  3. Click “Tutorial” to learn about how to classify signals.
  4. Watch the brief video and pick one of the five categories for signals.
  5. Check out the “Field Guide” for more examples and information.

UW–Madison physicists key in revealing neutrinos emanating from galactic neighbor with a gigantic black hole

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On Earth, billions of subatomic particles called neutrinos pass through us every second, but we never notice because they rarely interact with matter. Because of this, neutrinos can travel straight paths over vast distances unimpeded, carrying information about their cosmic origins.

Although most of these aptly named “ghost” particles detected on Earth originate from the Sun or our own atmosphere, some neutrinos come from the cosmos, far beyond our galaxy. These neutrinos, called astrophysical neutrinos, can provide valuable insight into some of the most powerful objects in the universe.

For the first time, an international team of scientists has found evidence of high-energy astrophysical neutrinos emanating from the galaxy NGC 1068 in the constellation Cetus.

The detection was made by the National Science Foundation-supported IceCube Neutrino Observatory, a 1-billion-ton neutrino telescope made of scientific instruments and ice situated 1.5-2.5 kilometers below the surface at the South Pole.

These new results, to be published tomorrow (Nov. 4, 2022) in Science, were shared in a presentation given today at the Wisconsin Institute for Discovery.

“One neutrino can single out a source. But only an observation with multiple neutrinos will reveal the obscured core of the most energetic cosmic objects,” says Francis Halzen, a University of Wisconsin–Madison professor of physics and principal investigator of the IceCube project. “IceCube has accumulated some 80 neutrinos of teraelectronvolt energy from NGC 1068, which are not yet enough to answer all our questions, but they definitely are the next big step toward the realization of neutrino astronomy.”

For the full story, please visit https://news.wisc.edu/uw-madison-scientists-and-staff-key-in-revealing-neutrinos-emanating-from-galactic-neighbor-with-a-gigantic-black-hole/

 

IceCube analysis indicates there are many high-energy astrophysical neutrino sources

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This story was originally published by WIPAC

Back in 2013, the IceCube Neutrino Observatory—a cubic-kilometer neutrino detector embedded in Antarctic ice—announced the first observation of high-energy (above 100 TeV) neutrinos originating from outside our solar system, spawning a new age in astronomy. Four years later, on September 22, 2017, a high-energy neutrino event was detected coincident with a gamma-ray flare from a cosmic particle accelerator, a blazar known as TXS 0506+056. The coincident observation provided the first evidence for an extragalactic source of high-energy neutrinos.

The identification of this source was possible thanks to IceCube’s real-time high-energy neutrino alert program, which notifies the community of directions and energies of individual neutrinos that are most likely to have come from astrophysical sources. These alerts trigger follow-up observations of electromagnetic waves from radio up to gamma-ray, aimed at pinpointing a possible astrophysical source of high-energy neutrinos. However, the sources of the vast majority of the measured diffuse flux of astrophysical neutrinos still remain a mystery, as do how many of those sources exist. Another mystery is whether the neutrino sources are steady or variable over time and, if variable, whether they vary over long or short time scales.

In a paper recently submitted to The Astrophysical Journal, the IceCube Collaboration presents a follow-up search that looked for additional, lower-energy events in the direction of the high-energy alert events. The analysis looked at low- and high-energy events from 2011-2020 and was conducted to search for the coincidence in different time scales from 1,000 seconds up to one decade. Although the researchers did not find an excess of low-energy events across the searched time scales, they were able to constrain the abundance of astrophysical neutrino sources in the universe.

a map of celestial coordinates with ovoid lines shown as a heatmap of locations where neutrino candidate events likely originated
Map of high-energy neutrino candidates (“alert events”) detected by IceCube. The map is in celestial coordinates, with the Galactic plane indicated by a line and the Galactic center by a dot. Two contours are shown for each event, for 50% and 90% confidence in the localization on the sky. The color scale shows the “signalness” of each event, which quantifies the likelihood that each event is an astrophysical neutrino rather than a background event from Earth’s atmosphere. Credit: IceCube Collaboration

This research also delves into the question of whether the astrophysical neutrino flux measured by IceCube is produced by a large number of weak sources or a small number of strong sources. To distinguish between the two possibilities, the researchers developed a statistical method that used two different sets of neutrinos: 1) alert events that have a high probability of being from an astrophysical source and 2) the gamma-ray follow-up (GFU) sample, where only about one to five out of 1,000 events per day are astrophysical.

“If there are a lot of GFU events in the direction of the alerts, that’s a sign that neutrino sources are producing a lot of detectable neutrinos, which would mean there are only a few, bright sources,” explained recent UW–Madison PhD student Alex Pizzuto, a lead on the analysis who is now a software engineer at Google. “If you don’t see a lot of GFU events in the direction of alerts, this is an indication of the opposite, that there are many, dim sources that are responsible for the flux of neutrinos that IceCube detects.”

a graph with power of each individual source on the y-axis and number density of astrophysical neutrino sources on the x-axis. there is a clear indirect relationship, with the lines starting in the upper left and moving toward the lower right of the graph. three "lines" are shown: an upper blue band that says "diffuse," a middle black lines that says "upper limit; this analysis" and a blue-green band that has +/-1 sigma sensitivity
Constraints on the luminosity (power) of each individual source as a function of the number density of astrophysical neutrino sources (horizontal axis). Previous IceCube measurements of the total astrophysical neutrino flux indicate that the true combination of the two quantities must lie within the diagonal band marked “diffuse.” The results of the new analysis are shown as an upper limit, compared to the sensitivity, which shows the range of results expected from background alone (no additional signal neutrinos associated with the directions of alert events). The upper limit is above the sensitivity because there is a statistical excess in the result (p = 0.018). Credit: IceCube Collaboration

They interpreted the results using a simulation tool called FIRESONG, which looks at populations of neutrino sources and calculates the flux from each of these sources. The simulation was then used to determine if the simulated sources might be responsible for producing a neutrino event.

“We did not find a clear excess of low-energy events associated with the high-energy alert events on any of the three time scales we analyzed,” said Justin Vandenbroucke, a physics professor at UW–Madison and colead of the analysis. “This implies that there are many astrophysical neutrino sources because, if there were few, we would detect additional events accompanying the high-energy alerts.”

Future analyses will take advantage of larger IceCube data sets and higher quality data from improved calibration methods. With the completion of the larger next-generation telescope, IceCube-Gen2, researchers will be able to detect even more dim neutrino sources. Even knowing the abundance of sources could provide important constraints on the identity of the sources.

“The future is very exciting as this analysis shows that planned improvements might reveal more astrophysical sources and populations,” said Abhishek Desai, postdoctoral fellow at UW–Madison and co-lead of the analysis. “This will be due to better event localization, which is already being studied and should be optimized in the near future.”

+ info “Constraints on populations of neutrino sources from searches in the directions of IceCube neutrino alerts,” The IceCube Collaboration: R. Abbasi et al. Submitted to The Astrophysical Journal. arxiv.org/abs/2210.04930.