Events at Physics |
Events During the Week of September 11th through September 18th, 2022
Monday, September 12th, 2022
- Plasma Physics (Physics/ECE/NE 922) Seminar
- Formation and Particle Acceleration in Large-Scale Diamagnetic Cavities at the Boundary of Earth’s Magnetic Shield
- Time: 12:00 pm
- Place: 1610 Engineering Hall
- Speaker: Katariina Nykyri, Embry-Riddle University
- Abstract: Earth’s magnetic field resembles that of the bar-magnet where magnetic field converges (diverges) toward northern (southern) hemisphere at the high-latitudes creating two funnel-like structures called geomagnetic cusps. Because the magnetic field around the cusps rotates by 360 degrees, there always exist regions where geomagnetic field and interplanetary magnetic field (IMF) are anti-parallel in the vicinity of the cusps, leading to magnetic reconnection if plasma flow is sub-Alfvenic along the k-vector of the tearing instability. On the other hand, the magnetosheath flow is perpendicular to cusp field both at the dawn and dusk sectors of the high-altitude cusps, leading to Kelvin-Helmholtz Instability and associated secondary processes.
Cluster and MMS spacecraft observations have revealed that magnetic reconnection (both at the high- and the low-latitudes) can create large-scale diamagnetic cavities in the high-latitude magnetosphere where particles can be accelerated to 100s of keV in the reconnection quasi-potential. The acceleration mechanism creates strongly perpendicular pitch angle distributions for ions and electrons, likely contributing to the source for the observed ion temperature anisotropy in the high-latitude magnetosphere. Recently, 4 MMS spacecraft flew through a dusk- sector southern hemispheric diamagnetic cavity observing strong ULF wave activity, driven by the drift-mirror instability, at the edge of the cavity. The high-energy electrons within these wave field depressions showed counter-streaming pitch angle distributions while ions remained trapped. MMS spacecraft also have detected high-energy trapped electrons and occasionally parallel streaming high-energy ions within Kelvin-Helmholtz waves at high-latitudes, in the vicinity of the Southern hemispheric dawn-sector cusp.
In this talk I demonstrate the formation mechanism of these diamagnetic cavities, show the observed and simulated signatures of particle acceleration, as well as discuss the possible physical mechanisms leading to their escape from the cavities and their subsequent faith and consequences for magnetospheric energy and mass budget, and on the origin of seed population of the radiation belts.
As cusp-like structures are universal, these cavity-associated acceleration mechanisms may be important also for plasma energization in other systems, e.g., in the atmospheres of magnetized stars. The ~four-orders of magnitude energy increase, associated with this process, may also be important for plasma energization in laboratory plasmas with cusp-like configurations.
- Host: Benedikt Geiger
- Theory Seminar (High Energy/Cosmology)
- The Partonic Picture at High-Energy Lepton Colliders
- Time: 4:00 pm
- Place: Chamberlin 5280
- Speaker: Yang Ma, University of Pittsburgh
- Abstract: After the triumph of discovering the Higgs boson at the CERN Large Hadron Collider, people are getting increasingly interested in studying the Higgs properties in detail and searching for the physics beyond the Standard Model (SM). A multi-TeV lepton collider provides a clean experimental environment for both the Higgs precision measurements and the discovery of new particles. In high-energy leptonic collisions, the collinear splittings of the leptons and electroweak (EW) gauge bosons are the dominant phenomena, which could be well described by the parton picture. In the parton picture, all the SM particles should be treated as partons that radiated off the beam particles, and the electroweak parton distribution functions (EW PDFs) should be adopted as a proper description for partonic collisions of the initial states. Along this line, future ultra-high-energy lepton colliders can be treated as EW version of LHCs. In our work, both the EW and the QCD sectors are included in the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) formalism to perturbatively resum the potential large logarithms emerging from the initial-state radiation (ISR). I will show the results of QCD jet production as well as some other typical SM processes at a possible high-energy electron-positron collider and a possible high-energy muon collider obtained using the PDFs.
- Host: George Wojcik
Tuesday, September 13th, 2022
- Picnic planning
- Dept Picnic planning meeting
- Time: 12:00 pm - 1:00 pm
- Place: 4274 Chamberlin Hall
- Speaker: Sharon Kahn
- Abstract: If you have ideas for fun picnic activities or just want to lend a hand with some planning, join us for a picnic planning meeting on Tuesday, Sept 13, noon -1pm, 4274 Chamberlin.
REMINDER: Picnic will be Sat, Sept 24 - Please RSVP here (https://bit.ly/3U1dvzN ) to let us know if you and yours are coming so we can be sure to have enough food! - Council Meeting
- Time: 3:00 pm - 4:00 pm
- Place: 4272 Chamberlin Hall
- Speaker: Mark Eriksson, UW-Madison
- Host: Mark Eriksson
Wednesday, September 14th, 2022
- Academic Calendar
- Deadline to drop a course or withdraw from the university without having the course(s) appear on the transcript
- Abstract: *Note: actual end time may vary.* CONTACT: 262-3811, registrar@em.wisc.edu URL:
- Wisconsin Quantum Institute
- Quantum Information Science (QIS) Career Fair
- Time: 10:00 am - 4:00 pm
- Place: Virtual, learn more and register at
- Speaker: various, U.S. Department of Energy Office of Science
- Abstract: The Quantum Information Science Career Fair, sponsored by the U.S. Department of Energy's Office of Science's National Quantum Information Science (QIS) Research Centers, aims to bring awareness to two- and four-year college and graduate students and post-doc to the wide range of QIS careers they can pursue—from technical and scientific roles to non-STEM roles that facilitate research and bring awareness to the field, like marketing and human resources.
Participants will hear from experts in their field, get their questions answered, build their professional networks, and meet one-on-one with potential employers. The event will showcase opportunities available within the Centers, national laboratories, academic institutions, and industry.
This QIS Career Fair is a public event and sessions will be recorded. All participants must register online by September 14, 2022 to attend. Please contact the Career Fair Coordinator with questions. - Host: Department of Energy Office of Science
- Department Meeting
- Time: 12:15 pm - 1:00 pm
- Place: B343 Sterling Hall
- Speaker: Mark Eriksson, UW-Madison, Physics
- Monthly Department Meeting
- Host: Mark Eriksson
- Theory Seminar (High Energy/Cosmology)
- The BOSS bispectrum analysis at one loop from the Effective Field Theory of Large-Scale Structure
- Time: 4:00 pm
- Place: Chamberlin 5280
- Speaker: Matthew Lewandowski, Northwestern U.
- Abstract: In this talk, I will discuss our recent analysis of the BOSS power spectrum monopole and quadrupole, and the bispectrum monopole and quadrupole data, using the predictions from the Effective Field Theory of Large-Scale Structure (EFTofLSS). Specifically, we use the one-loop prediction for the power spectrum and the bispectrum monopole, and the tree level for the bispectrum quadrupole. After validating our pipeline against numerical simulations as well as checking for several internal consistencies, we apply it to the observational data. We find that analyzing the bispectrum monopole to higher wavenumbers thanks to the one-loop prediction, as well as the addition of the tree-level quadrupole, significantly reduces the error bars with respect to our original analysis of the power spectrum at one loop and bispectrum monopole at tree level. We find significant error bar reduction with respect to the power spectrum-only analysis. Remarkably, the results are compatible with the ones obtained with a power-spectrum-only analysis, showing the power of the EFTofLSS in simultaneously predicting several observables. We find no tension with Planck.
- Host: George Wojcik
Thursday, September 15th, 2022
- GREAT IDEAS DEI Reading Group
- Special GREAT IDEAS DEI Discussion: Prof. Marin-Spiotta, Humanities Education for Anti-Racism Literacy (HEAL) in the Sciences: Informing Research and Teaching Practices
- Time: 12:30 pm - 2:00 pm
- Place: Chamberlin 5280
- Speaker: Prof. Marin-Spiotta, UW-Madison Dept. of Geography
- Abstract: Join us for a special GREAT IDEAS DEI Discussion facilitated by Prof. Marin-Spiotta about the UW Humanities Education for Anti-Racism Literacy in the Sciences and Medicine (HEAL) project. Prof. Marin-Spiotta is a UW professor in biogeochemistry, biogeography, and global change, and is one of the key team members for this project. The HEAL project seeks to advance anti-racist practices and pedagogies for higher education in STEMM (science, technology, engineering, mathematics, and medicine) by creating models and tools that would increase the equitability of our university and society.
- Host: GMaWiP and Climate and Diversity Committee (R. Sassella and Elizabeth Baldridge)
Friday, September 16th, 2022
- Academic Calendar
- Deadline for students to add, swap, or change sections in a Fall term course
- Abstract: *Note: actual end time may vary.* CONTACT: 262-3811, registrar@em.wisc.edu URL:
- Academic Calendar
- Deadline for students to begin initial Fall enrollment
- Abstract: *Note: actual end time may vary.* CONTACT: 262-3811, registrar@em.wisc.edu URL:
- Academic Calendar
- Deadline for students to drop a Fall term course and receive 100% tuition adjustment
- Abstract: *Note: actual end time may vary.* CONTACT: 262-3811, registrar@em.wisc.edu URL:
- Physics Department Colloquium
- Vera C. Rubin Observatory: from Commissioning to Cosmology
- Time: 3:30 pm - 6:00 pm
- Place: 2103 Chamberlin Hall
- Speaker: Keith Bechtol
- Abstract: Our observed universe is one statistical realization of the fundamental laws of nature enacted on the grandest scale. As observational cosmologists, we survey increasingly large volumes of the universe to help ascertain those laws with improved accuracy and precision. Experiments at the cosmic frontier have demonstrated that measurements of the cosmic expansion history and growth of structure are sensitive to physics beyond the Standard Model, including the nature of dark energy, massive neutrinos, the initial conditions of the Universe (e.g., inflation), and the particle properties of dark matter. Continuing this enterprise, the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) will catalog more galaxies and collect precision lightcurves for more supernovae during its first year of science operations in 2024-2025 than all previous cosmic surveys combined. The Rubin Observatory construction project is now actively engaged in system integration, test, and commissioning with engineering "first light" expected in mid-2023. I will discuss the pathway from commissioning to realizing the scientific potential of Rubin Observatory.