Events During the Week of March 2nd through March 9th, 2025
Monday, March 3rd, 2025
- Plasma Physics (Physics/ECE/NE 922) Seminar
- "Multi-fidelity digital models for fusion energy device optimization, design, and operation"
- Time: 12:00 pm - 1:15 pm
- Place: 1227 Engineering Hall
- Speaker: Michael Churchill, Princeton Plasma Physics Laboratory
- Abstract: Digital modelling of the physics and engineering of next-step fusion devices will become increasingly important for their successful design and operation. A classical divide exists between modeling relying on pure simulation and pure experimental scaling laws (the so-called “sim2real” gap). High-fidelity modeling can help to close this gap, but often does not fulfill the speed needed for certain workflows such as design optimization and control room analysis. I will present several efforts and techniques including AI/ML and advanced optimization being pursued towards building out faithful digital twins, based on a range of simulations covering differing physics and levels of fidelity. Examples will range from stellarator design optimization with the StellFoundry SciDAC collaboration, to fast simulation-based inference with experimental diagnostics.
- Host: Prof. Adelle Wright
- Theory Seminar (High Energy/Cosmology)
- Cavendish Tests of Millicharged Relics
- Time: 1:00 pm - 2:30 pm
- Place: Chamberlin 5280
- Speaker: Asher Berlin, Fermilab
- Abstract: The simplest cosmologies motivate the consideration of dark matter subcomponents that interact significantly with normal matter. Moreover, such strongly-coupled relics may have evaded detection to date if upon encountering the Earth they rapidly thermalize down to terrestrial temperatures, well below the thresholds of most existing dark matter detectors. This motivates the consideration of alternative detection techniques sensitive to a terrestrial population of slowly-moving dark matter particles. In this talk, I will focus on such a population of millicharged particles, and show how reinterpretations of Cavendish tests of Coulomb's Law, first performed in the late 18th century, provide some of the strongest bounds on this largely unexplored parameter space. Event recording:
- Host: Dan Hooper
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- Towards Differentiable Physics Analysis at the High-Luminosity Large Hadron Collider and Beyond
- Time: 4:00 pm - 5:00 pm
- Place: 5280 CH &
- Speaker: Dr. Matthew Feickert, University of Wisconsin - Madison
- Abstract: With the High-Luminosity Large Hadron Collider (HL-LHC) era on the horizon for physics analysis at the LHC experiments, there are multiple data, computing, and analysis challenges to be overcome to efficiently analyze and extract the most scientific value from the unique and valuable data collected. These challenges also offer opportunities for innovation. How can new data science tools maximize analysis efficiency to reduce the time to insight? How can applications of artificial intelligence and machine learning (AI/ML) increase analysis sensitivity to reach new results sooner with less data? What previously computationally unfeasible analyses are unlocked by intelligently scaling analysis workflows? In this seminar, I will present an overview for how we can apply powerful new tools and technologies to meet these challenges, advance the frontiers of particle physics, and open doors of collaboration with other fields. We'll explore an ecosystem of modern open source data science tools that is enabling new physics analysis workflows at scale. We'll then discuss how AI/ML techniques and applications from the broader fields of automatic differentiation and differentiable programming are being integrated into analysis at the LHC, offering new opportunities. Finally, I will demonstrate how strategies for enabling analysis reuse can be leveraged to tackle scientific workflows at the HL-LHC scale and beyond, unlocking new approaches to analyses.
- Host: Sridhara Dasu
Tuesday, March 4th, 2025
- No events scheduled
Wednesday, March 5th, 2025
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- Invisible Cities: Imagining the next era of AI-enabled fundamental physics research
- Time: 4:00 pm - 5:00 pm
- Place: 5280 CH &
- Speaker: Dr. Mariel Pettee, Lawrence Berkeley Laboratory
- Abstract:
To achieve some of the biggest physics discoveries in the last decade, including the Higgs boson, gravitational waves, and black holes, physicists had to radically re-imagine the paradigm of working in small teams and instead construct large-scale experimental collaborations of hundreds or even thousands of scientists. The recent success of large-scale AI "foundation models" in various domains begs the question: could our scientific conventions yet again be restricting our access to major discoveries? In this talk, I propose that a multi-disciplinary approach to fundamental physics research will be critical to finally answering the grand scientific mysteries about our Universe that have thus far eluded our usual strategies. To achieve this vision, AI methods can help us publish detector-agnostic datasets, construct richer embeddings of our data, and highlight connections across varied domains -- but we also need to take care to ensure that we design these tools to uphold our highest priorities as scientists.
Shot Bio: Dr. Mariel Pettee is an interdisciplinary scientist based in Brooklyn, NY. She is a Chamberlain Postdoctoral Research Fellow at Lawrence Berkeley National Laboratory, a visiting researcher at the Flatiron Institute Center for Computational Astrophysics in New York City, and a member of the ATLAS Experiment at CERN. Her scientific research is centered on developing new AI methods to help make discoveries in high-energy particle physics and astrophysics. As a founding member of the Polymathic AI collaboration, she is interested in harnessing multidisciplinary AI foundation models for scientific insight. She received a PhD in Physics from Yale University, a Masters in Physics at the University of Cambridge, and a Bachelors in Physics & Mathematics from Harvard University.
- Host: Sridhara Dasu
Thursday, March 6th, 2025
- R. G. Herb Condensed Matter Seminar
- Quantum many-body scars in Rydberg atom simulators
- Time: 10:00 am - 6:00 pm
- Place: 5310 Chamberlin
- Speaker: Ian Mondragon Shem, Northwestern
- Abstract: Quantum simulators have led to significant insight into the non-equilibrium behavior of quantum many-body systems. Programmable Rydberg atom simulators, in particular, have uncovered the existence of persistent oscillations of local observables due to the emergence of quantum many-body scars. The conventional understanding of these scar states purports that they form a small subset of non-ergodic eigenstates embedded in a thermal spectrum. In this talk, we will show that the PXP model, which closely describes strongly interacting Rydberg atoms, can exhibit many more scarred states than had been previously identified. We will present evidence that the magnetization and temporal correlators of the system exhibit oscillations for almost any initial product state with a frequency close to that of the conventional set of scars. We will argue that these oscillations arise due to multiple sets of scars that satisfy an approximate su(2) algebra. We will further explore the impact that this structure has on the system's dynamics in the presence of disorder. Finally, we will discuss a strategy to detect the presence of these new scarred states using quantum typically.
- Host: Maxim Vavilov
- Astronomy Colloquium
- The Milky Way as a Prototypical Disk Galaxy: Galactic Archeology and Chemical Evolution in Context
- Time: 3:30 pm - 4:30 pm
- Place: 4421 Sterling Hall
- Speaker: Boquan Erwin Chen, Ohio State University
- Abstract: The chemical evolution of the Milky Way has long been regarded as uniquely complex, epitomized by its distinct dual [α/Fe] sequences. This perceived intricacy has driven interpretations reliant on multi-phase formation models, such as the two-infall framework. Yet, breakthroughs in Galactic archeology—powered by Gaia astrometry and large-scale spectroscopic surveys—are challenging this narrative, revealing that the Milky Way’s chemical evolution may align closely with processes observed in typical disk galaxies. In this talk, I will present a unified, physically motivated model of chemical evolution that reframes the Milky Way not as an outlier but as a galactic archetype. We demonstrate that key observables—including the radial metallicity gradient, stellar metallicity distribution, and age-abundance trends—can be simultaneously reproduced under a coherent framework consistent with generic disk galaxy formation. By reconciling these features without invoking exceptional mechanisms, our results suggest that the Milky Way’s apparent complexity stems from its detailed observational record rather than atypical evolutionary pathways. Furthermore, the archetypal nature of the Milky Way may extend to its very origins, implying that its early assembly followed pathways common to disk galaxies. Nevertheless, stellar-level observations of the M31 Andromeda galaxy and Large Magellanic Cloud (LMC) highlight the diversity of galactic chemical evolution. This renewed perspective positions our Galaxy as a critical benchmark for deciphering the universal processes shaping disk galaxies across cosmic time, offering insights that bridge local precision to extragalactic contexts.
- Host: Melinda Soares-Furtado
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- Seeing with Structure: Physics and The Art of Model-Building
- Time: 4:00 pm - 5:00 pm
- Place: 5280 CH &
- Speaker: Dr. Garrett Merz, University of Wisconsin - Madison
- Abstract: Physics datasets are highly structured, and studying how and when this structure is (or is not) learnable by neural network models offers an exciting new way to pose questions about our data. In this talk, I will explore applications of this thinking to problems in both experimental and theoretical high-energy physics: to the discovery of new patterns in the mathematical structure of theoretical physics data, to large-scale "Foundation Modelling" questions that span diverse experimental settings ranging from collider physics to cosmology, and to pose future questions that might allow us to bridge the gap between experimental and theoretical domains. By studying how and when models represent symmetries and patterns, I explore ways in which physicists can use models themselves as structure probes, which may enable radically new ways of formulating questions about the Universe.
- Host: Sridhara Dasu
Friday, March 7th, 2025
- Graduate Program Event
- Prospective Visit Days
- Time: 8:30 am
- Place: all over Chamberlin
- Abstract: This weekend, we'll host several prospective PhD student visitors to the department. Please welcome them as you see them around Chamberlin!
- Host: Sharon Kahn
- Climate & Diversity
- Diversity Forum Fridays: Fostering Psychological Safety to Enhance Belonging and Community
- Time: 9:00 am - 10:30 am
- Place: in Chamberlin 5310 & Zoom
- Abstract: For over 20 years, UW–Madison has hosted the annual Diversity Forum for participants to engage in discourse and education on contemporary issues related to creating equitable and inclusive learning and working environments.
2024 Theme: Threads of Belonging: Navigating Differences and Building Community
Fostering Psychological Safety to Enhance Belonging and Community explores the critical role of psychological safety in fostering inclusive environments where every individual feels valued and able to bring their full selves to the community. Drawing from Madison College’s Psychological Safety training program, we will delve into best practices for creating and sustaining psychologically safe spaces that promote diversity, inclusion, and a sense of belonging. Our workshop offers a comprehensive understanding of psychological safety and its significance in creating inclusive environments that facilitate belonging and success. Through engaging activities and discussions, we’ll deepen understanding of the challenges faced by underrepresented groups and explore effective culturally responsive practices. Our session integrates principles of psychological safety, restorative practices, and intersectionality to drive meaningful change. Attendees will learn about the foundational concepts covered in the program and leave with actionable steps and innovative tools for building inclusive communities and fostering belonging for all. - Host: Rachel Zizmann
- HXS Group Meeting
- "Real-Time Plasma Control of LHD by Data Assimilation System: ASTI"
- Time: 2:30 pm - 3:10 pm
- Place: 106 Engineering Research Bldg
- Speaker: Prof. Sadayoshi Murakami, Kyoto University
- Abstract: We develop a model predictive control system for fusion plasmas based on data assimilation, which integrates predictive model (digital twin) adaptation using real-time measurements and control estimation robust against model and observation uncertainties. The main part of the control system, ASTI, predicts the probability distribution of future plasma states and estimates the optimal control input and the actual plasma state based on Bayes' theorem. In this study, the ASTI-centered control system has been implemented in the Large Helical Device (LHD) and successfully applied to control the electron and ion temperatures and electron density. The control experiments demonstrate the effectiveness of the data assimilation-based control approach, which allows the synergistic interaction of measurement, heating, fueling, and simulation. This approach can provide a flexible platform for the digital twin control of future fusion reactors.
- Host: Prof. Benedikt Geiger
- HXS Group Meeting
- "Status of design activity of QA-QI flexible stellarator at NIFS"
- Time: 3:15 pm - 3:55 pm
- Place: 106 Engineering Research Bldg
- Speaker: Prof. Hiroyuki Yamaguchi, National Institute for Fusion Studies
- Abstract: As a candidate for the post-Large Helical Device at National Institute for Fusion Science (NIFS), Japan, our research group has been designing a new stellarator-type experiment device, Variable Symmetry Torus (VAST). To study the effect of particle motion on the collective phenomena in plasma, such as micro-turbulences, magnetic flexibility is emphasized in designing VAST: both quasi-axisymmetric (QA) and quasi-isodynamic (QI)-like magnetic configurations can be realized in a single device. With the basic design for modular and auxiliary coils being almost fixed, the physics design of VAST has made substantial progress in the last year. Both QA and QI-like modes have been confirmed to have finite-beta MHD equilibria with good magnetic surfaces. Gyrokinetic simulations have shown clear differences in ion-temperature-gradient driven turbulence and associated zonal flows between these configurations. Recent attempts to predict plasma performances and heating scenarios by integrated simulation will also be presented.
- Host: Prof. Benedikt Geiger
- Physics Department Colloquium
- Investigating cosmic origin and evolution with the oldest photons
- Time: 3:30 pm - 4:30 pm
- Place: 2241 CH
- Speaker: Zeeshan Ahmed, SLAC National Accelerator Laboratory
- Abstract: The red-hot glow of the primordial universe, after 13.8 billion years of redshift, is observed today by our telescopes as the Cosmic Microwave Background (CMB). Spatial variations of CMB intensity and polarization across the sky provide a record of conditions in the early universe, possibly encoding signatures from cosmic inflation and traces of undiscovered relic particles. Additionally, the CMB ‘backlights’ the universe’s large-scale structure and picks up the influence of all matter, including neutrinos, on its way to us. Ground-based CMB imaging instrumentation has made generational leaps in sensitivity over the past few decades, while our understanding and mitigation of systematic errors in CMB measurements has advanced. Ongoing and upcoming experiments such as BICEP, South Pole Telescope and Simons Observatory will conduct the most sensitive search yet for inflation, complement DESI and Rubin Observatory in aiding our understanding of cosmic acceleration, and enhance studies of neutrinos and dark matter from direct experimental efforts. Additionally, a future observatory called CMB-S4 is the largest conceived ground-based CMB facility that plans to map over 40% of the Southern sky to unprecedented sensitivity in the 2030s. I will report on the design, status and latest results from these efforts.
- Host: Sridhara Dasu