Events at Physics |
Events During the Week of February 2nd through February 9th, 2020
Monday, February 3rd, 2020
- Plasma Physics (Physics/ECE/NE 922) Seminar
- How does the magnetosphere go to sleep? Combining global scale simulations and observations to reveal fundamental behaviors of the magnetosphere
- Time: 12:05 pm - 12:55 pm
- Place: 2241 Chamberlin Hall
- Speaker: Therese Moretto Jørgensen, University of Bergen, Norway
- Abstract: The Earth's magnetic field presents an obstacle to the streaming magnetized plasma of the solar wind, thereby creating the magnetosphere. The solar wind, magnetosphere, and ionosphere together constitute a fascinating, complex, and highly dynamic system of interacting plasmas in the space environment near Earth, which we can study with satellites and ground-based observations. Much has been learned over the last several decades about the dynamics of this system and the processes involved but many intriguing questions remain. This talk will present a recent study of one such interesting question in magnetospheric research related to the transition between magnetospheric configurations under substantial solar wind driving, and a putative relaxed state after the driving ceases.
Energy and circulation in the Earth’s magnetosphere and ionosphere are largely determined by conditions in the solar wind and interplanetary magnetic field. When the driving from the solar wind is turned off (to a minimum), we expect the activity to die down but exactly how this happens is not known. Utilizing global MHD modelling, we have addressed the questions of what constitutes the quietest state for the magnetosphere and how it is approached following a northward turning in the IMF that minimizes the driving. We observed an exponential decay with a decay time of about 1 hr in several integrated parameters related to different aspects of magnetospheric activity, including the total field-aligned current into and out of the ionosphere. The time rate of change for the cessation of activity was also measured in total field aligned current estimates from the AMPERE project, adding observational support to this finding.
The talk will give a brief introduction to magnetosphere research and the background for the study. The simulation models and observational data will be presented and the results will be explained and discussed in terms of their physical interpretation as it relates to magnetosphere dynamics and magnetosphere-ionosphere coupling.
Tuesday, February 4th, 2020
- Chaos & Complex Systems Seminar
- Anesthesia in the Anthropocene: Environmental and economic considerations of modern anesthesia and surgery
- Time: 12:05 pm - 1:00 pm
- Place: 4274 Chamberlin (refreshments will be served)
- Speaker: Mike Ries, UW Department of Anesthesiology
- Abstract: Climate health and population health are undeniably and inextricably linked. As healthcare institutions maintain a moral obligation to the healing of all the world's citizens, and healthcare being a significant, environmentally burdensome business, there exists a large motive and opportunity for "greening" healthcare. Even further, the operating room has been singled out as the most polluting and most energy-intensive part of the modern healthcare ecosystem. As the perioperative expert, this places a moral and economic obligation on anesthesiologists to improve environmental standards in the operating room. During this talk we will discuss the complex environmental and economic problems facing the healthcare industry and more specifically how "greening" the OR is the right choice for checkbooks and our environment alike.
- Host: Clint Sprott
- "Physics Today" Undergrad Colloquium (Physics 301)
- Spintronics and Mulitiferroics
- Time: 1:20 pm - 2:10 pm
- Place: 2241 Chamberlin Hall
- Speaker: Mark Rzchowski, UW Madison Department of Physics
- Host: Sridhara Dasu
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- Disentangling a century-old mystery: a path to unveiling the origins of the ultra-high-energy Universe
- Time: 3:30 pm
- Place: Room 4274, Chamberlin
- Speaker: Lu Lu
- Abstract: The highest-energy particles discovered in Nature are ultra-high-energy cosmic rays (UHECR). They carry energies orders of magnitude higher than that reached by man-made accelerators. Technological advances in the past thirty years have enabled us to precisely characterize the flux, composition, and arrival directions of UHECR. The Pierre Auger Observatory, the largest cosmic-ray experiment on Earth, is an observatory dedicated to the study of UHECR by detecting air showers produced in Earth's atmosphere. Additionally, the cubic-kilometer IceCube Neutrino Observatory has discovered a diffuse flux of high-energy astrophysical neutrinos at PeV energies. However, the origins of UHECR remain an enduring mystery, and their connections with IceCube neutrinos remain unclear. In this talk, I will review the state-of-the-art for our understanding of the UHE Universe and propose a road map that combines measurements from Pierre Auger, IceCube and other multi-messenger partners, utilizing data of UHE photons and astrophysical neutrinos, for the detection of the first possible UHE source.
- Host: Albrecht Karle
Wednesday, February 5th, 2020
- No events scheduled
Thursday, February 6th, 2020
- R. G. Herb Condensed Matter Seminar
- Studying superconductors using NV-centers in diamond optical magnetometry
- Time: 10:00 am
- Place: 5310 Chamberlin
- Speaker: Ruslan Prozorov, Iowa State/Ames Lab
- Abstract: The variation of magnetic fields across the superconducting samples is quite small in the fragile genuine Meissner state, which is easily disturbed by Abrikosov vortex pining and field inhomogeneities due to large demagnetization effects. We developed minimally invasive optical magneto-sensing based on the ensembles of NV centers in diamond crystal to study Meissner state structure and to determine the lower critical field. I will show how different the structure of the Meissner state is in different superconducting materials. I will also discuss the application of the NV sensing to identify quantum phase transition in charge-doped iron-based superconductors.
- Host: Alex Levchenko
- Cosmology Journal Club
- Time: 12:00 pm - 1:00 pm
- Place: 5242 Chamberlin Hall
- Abstract: We discuss papers from arxiv.org related to cosmology each week. All are welcome and feel free to bring your lunch. If there is a paper you would like to present, or have questions or comments, please email Ross Cawthon (cawthon@wisc.edu) and Santanu Das (sdas33@wisc.edu).
- Astronomy Colloquium
- X-raying the Intersellar Medium
- Time: 3:30 pm - 5:00 pm
- Place: 4421 Sterling Hall, Coffee and cookies 3:30 PM, Talk begins 3:45 PM
- Speaker: Dr. Eddie Schalfly, Lawrence Berkeley National Laboratory
- Abstract: The interstellar medium (ISM) is the fuel of star formation, and its scattering and absorption of light transforms the Galactic radiation field. Despite its importance, most observations of the Milky Way's ISM are limited to two dimensions; its angular distribution is precisely measured, but its distribution in distance is much more uncertain. Large surveys of stars can be used to resolve this uncertainty. Because light from stars is absorbed and scattered by intervening material before observation on earth, the Galaxy's stars can be used as a dense network of lighthouses, effectively x-raying the ISM to reveal its 3D structure and properties. In this talk, I'll describe our ongoing program to use large surveys to map the ISM in 3D. We have mapped the density of dust in the ISM over the nearest 5 kpc at unprecedented resolution, highlighting complex networks of diffuse voids and dense star-forming regions. We have also been able to measure the size distribution of dust grains throughout the Milky Way, revealing kiloparsec-scale structures that may track variations in the Galactic star-formation rate and gas density. Numerous other projects are possible, ranging from studies of the 3D kinematics of the ISM to the Galactic magnetic field. New surveys and instruments like Gaia, SDSS-V, LSST, and JWST promise a bright future for 3D studies of the ISM, offering incredibly accurate distance measurements, order-of-magnitude larger samples of stars, and unrivalled sensitivitity.
- Host: Bob Benjamin, UWM
Friday, February 7th, 2020
- Theory Seminar (High Energy/Cosmology)
- Einstein’s Microscope: Uncovering Small-Scale Dark Matter Structures with Novel Gravitational Lensing Probes
- Time: 1:30 pm
- Place: 5280 Chamberlin
- Speaker: Liang Dai, Institute for Advanced Study
- Abstract: The physical nature of the astrophysical dark matter (DM) is a fundamental question in cosmology. The clustering structure of DM on sub-galactic scales is key to distinguishing between various viable DM models which all make successful predictions about the large-scale structure and galaxy formation, but empirical tests have been fundamentally hindered by the lack of electromagnetic tracers of sub-galactic structures. In this talk, I aim to introduce novel and practical gravitational-lensing based methods which can be employed to push forward this research frontier. I will first discuss the new phenomenon of extremely magnified cosmological sources as deep imaging of strong lensing clusters has recently started to uncover, and explain how this phenomenon can be exploited as a sensitive probe of compact halo objects, non-luminous DM subhalos smaller than those who host dwarf galaxies, and even (sub-)planetary mass DM minihalos as expected in the axion DM scenario. The full scientific potential of these new ideas will be realized as forthcoming photometric surveys will greatly expand the catalog of highly magnified lensed galaxies and deep follow-up observations with space-borne or ground-based optical/infrared telescopes will enable detailed studies of their lensed appearances. I will also discuss the exciting prospect to exploit lensing of alternative extragalactic sources such as fast radio bursts and gravitational waves from merging black holes to probe small-scale DM lenses. In particular, I will explain how one can extract unique information by observing wave diffraction of gravitational waves, which would be typically infeasible with electromagnetic sources.
- Host: Dan Chung
- Physics Department Colloquium
- Is This Even a Plasma? Physics of Strongly Coupled Plasmas
- Time: 3:30 pm
- Place: 2241 Chamberlin Hall
- Speaker: Scott Baalrud, University of Iowa
- Abstract: Plasma is often described as an ionized gas. However, a rapidly growing field of research is concerned with strongly coupled states of plasma that are more akin to ionized liquids, solids, or supercritical fluids. Strongly coupled plasmas are found in nature, including the interior of giant planets, the core of stars, and even in lightning bolts. The recent surge of interest has been driven by the advent of high-intensity lasers capable of ionizing, heating and compressing materials to tens of thousands of degrees at near solid density or several times compressed. These dense plasmas are not well described by either the methods of condensed matter theory (which deals with lower temperatures) or plasma theory (which deals with lower densities). Unique properties of this warm dense state of matter arise due to the combined influence of strong correlations amongst ions and Fermi degeneracy of electrons. This talk will present a new approach to kinetic theory that has made it practical to describe the dynamical transport properties of dense strongly coupled plasmas. It will also show how we have used simulations enabled by state-of-the-art high-performance computing to validate this theory.
- Host: John Sarff
Saturday, February 8th, 2020
- Wonders of Physics
- Annual Physics Fair
- Time: 11:00 am - 4:00 pm
- Place: Chamberlin Hall lobby and various rooms
- Speaker: Physics Dept faculty and students
- Wonders of Physics
- Wonders of Physics Show
- Time: 1:00 pm - 2:15 pm
- Place: 2103 Chamberlin
- Speaker: Clint Sprott, UW–Madison Physics
- Abstract: Scheduled presentations of The Wonders of Physics and a Physics Fair are given on the UW-Madison campus for the general public in mid-February each year. Free tickets are recommended and are available after January 1st using the On-Line Ticket Form (http://sprott.physics.wisc.edu/cgi-bin/tickleft.exe). Alternately, you may call (608) 262-2927 or e-mail wonders@physics.wisc.edu.
- Host: Clint Sprott / Wonders of Physics
- Wonders of Physics
- Time: 4:00 pm - 5:15 pm
- Place: 2103 Chamberlin
- Speaker: Clint Sprott, UW–Madison Physics
- Host: Clint Sprott / Wonders of Physics
- Wonders of Physics
- Wonders of Physics Show
- Time: 7:00 pm - 8:15 pm
- Place: 2103 Chamberlin
- Speaker: Clint Sprott, UW–Madison Physics
- Abstract: Scheduled presentations of The Wonders of Physics and a Physics Fair are given on the UW-Madison campus for the general public in mid-February each year. Free tickets are recommended and are available after January 1st using the On-Line Ticket Form (http://sprott.physics.wisc.edu/cgi-bin/tickleft.exe). Alternately, you may call (608) 262-2927 or e-mail wonders@physics.wisc.edu.
- Host: Clint Sprott / Wonders of Physics
Sunday, February 9th, 2020
- Wonders of Physics
- Wonders of Physics Show
- Time: 1:00 pm - 2:15 pm
- Place: 2103 Chamberlin
- Speaker: Clint Sprott, UW–Madison Physics
- Abstract: Scheduled presentations of The Wonders of Physics and a Physics Fair are given on the UW-Madison campus for the general public in mid-February each year. Free tickets are recommended and are available after January 1st using the On-Line Ticket Form (http://sprott.physics.wisc.edu/cgi-bin/tickleft.exe). Alternately, you may call (608) 262-2927 or e-mail wonders@physics.wisc.edu.
- Host: Clint Sprott / Wonders of Physics
- Wonders of Physics
- Wonders of Physics Show
- Time: 4:00 pm - 5:15 pm
- Place: 2103 Chamberlin
- Abstract: Scheduled presentations of The Wonders of Physics and a Physics Fair are given on the UW-Madison campus for the general public in mid-February each year. Free tickets are recommended and are available after January 1st using the On-Line Ticket Form (http://sprott.physics.wisc.edu/cgi-bin/tickleft.exe). Alternately, you may call (608) 262-2927 or e-mail wonders@physics.wisc.edu.
- Host: Clint Sprott / Wonders of Physics