Events at Physics |
Events During the Week of December 17th through December 24th, 2023
Sunday, December 17th, 2023
- Academic Calendar
- Commencement
- Time: 10:00 am - 11:00 am
- Abstract: URL:
Monday, December 18th, 2023
- Academic Calendar
- Exams
- Abstract: *Note: actual end time may vary.* URL:
Tuesday, December 19th, 2023
- Academic Calendar
- Exams
- Abstract: *Note: actual end time may vary.* URL:
- Graduate Program Event
- Cosmology at the Field Level with Probabilistic Machine Learning
- Time: 3:00 pm
- Place: 5310 CH
- Speaker: Adam Rouhiainen, Physics PhD Graduate Student
- Abstract: The large-scale structure is highly non-Gaussian at late times and small length scales, making it difficult to describe analytically. Parameter inference, data reconstruction, and data generation are greatly aided by various machine learning models, and this work takes a field level approach to solving these problems. The probability distribution of the large-scale structure is learned with normalizing flows, allowing Bayesian reconstruction of noisy fields with removed foregrounds. The normalizing flow is trained to be conditional on cosmological variables, from which accurate parameter estimation can be done. Turning to highly expressive denoising diffusion models, a super-resolution emulator is developed for large cosmological simulation volumes, allowing high-resolution simulation volumes to be conditionally generated from low-resolution volumes. The super-resolution emulator is trained to perform outpainting, and can thus upgrade very large cosmological volumes from low-resolution to high-resolution using an iterative outpainting procedure.
- Host: Moritz Münchmeyer
Wednesday, December 20th, 2023
- Academic Calendar
- Exams
- Abstract: *Note: actual end time may vary.* URL:
- Thesis Defense
- The Hall effect in Nonmagnetic, Ferromagnetic, and Antiferromagnetic Thin films
- Time: 9:00 am
- Place: 5310 CH
- Speaker: Neil Campbell, Physics PhD Graduate Student
- Abstract: While the Hall effect has been around for well over a century now, its utility as a probe of conducting, and especially magnetic, materials is as high as ever. As thin-film synthesis techniques continue expanding the boundaries of what materials are possible to create the Hall effect allows experimental probing of new and old phenomena in these films. Currently, Hall effects resulting from topological properties of materials are of high interest, be they from a topologically-protected band structure or a Berry phase that results from an antiferromagnetic spin arrangement. It was the goal of my research many times to observe such an effect, and in this regard the subsequent chapters could be viewed as a litany of failure. However, the investigations pursued did result in better understanding of the materials and in some cases, like in Pr2Ir2O7 finding new interesting phenomena. In this case I report that a broken symmetry as a result of growing the material in thin-film form results in a spin Hall effect that persists to much higher temperatures. Such a result suggests a road map for increasing the temperatures at which some low-temperature phenoma are observed. In SrIrO3 after pursuing a topolgical band structure, I ended up showing the lack of magnetic ordering in distorted Perovskite SrIrO3, which many researchers had presumed to exist. In the Mn3GaN chapters I use other magnetic characterizations and analysis to show the impact of heterostructring on magnetic anisotropy in a way that demonstrates a path for manipulating hard ferrimagnets to be amenable for spintronics. And finally use the well-known phenomenon of exchange bias to show how to break the degeneracy of antiferromagnetic domains, a problem that currently plagues many promising spintronic candidate materials.
- Host: Mark Rzchowski
Thursday, December 21st, 2023
- Academic Calendar
- Exams
- Abstract: *Note: actual end time may vary.* URL:
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- Neutrino signal from Cygnus region of the Milky Way
- Time: 2:30 pm - 3:30 pm
- Place: virtual via zoom
- Speaker: Andrii Neronov, Ecole Polytechnique (Lausanne) and Astroparticle and Cosmology laboratory (Paris)
- Abstract: Interactions of cosmic ray protons and nuclei in their sources and in the interstellar medium produce "hadronic" gamma-ray emission. Gamma-rays can also be of "leptonic" origin, i.e. originating from high-energy electrons accelerated together with protons. It is difficult to distinguish between hadronic and leptonic emission mechanisms based on gamma-ray data alone. This can be done via detection of neutrinos, because only hadronic processes lead to neutrino production. We use publicly available ten-year IceCube neutrino telescope dataset to demonstrate the hadronic nature of high-energy emission from the direction of Cygnus region of the Milky Way. We find a 3-sigma excess of neutrino events from an extended Cygnus Cocoon, with the flux comparable to the flux of gamma-rays in the multi-TeV energy range seen by HAWC and LHAASO telescopes.
- Host: Lu Lu
Friday, December 22nd, 2023
- Academic Calendar
- Graduate School Fall 2023: Master's degree deadline
- Time: 4:00 pm - 5:00 pm
- Abstract: CONTACT: 262-2433, gsacserv@grad.wisc.edu
Saturday, December 23rd, 2023
- No events scheduled
Sunday, December 24th, 2023
- Academic Calendar
- Fall Semester Grading deadline
- Abstract: *Note: actual end time may vary.* URL:
- Academic Calendar
- Graduate School Fall 2023: Doctoral degree deadline
- Time: 11:55 pm - 12:55 am
- Abstract: Degree candidates must complete all steps: CONTACT: 262-2433, gsacserv@grad.wisc.edu