Events at Physics
Events During the Week of October 4th through October 11th, 2020
- Plasma Physics (Physics/ECE/NE 922) Seminar
- Core transport model validation towards building the physics basis for the SPARC tokamak
- Time: 12:00 pm
- Place: Zoom Meeting
- Speaker: Pablo Rodriguez-Fernandez, Massachusetts Institute of Technology
- Abstract: The validation of turbulent transport simulations and integrated modeling frameworks is essential for the design of fusion devices that operate in unexplored burning plasma regimes. This talk presents work devoted to understanding the validity of the local transport approximation, widely used in current predictive frameworks. Cold-pulse experiments have long been considered strong evidence of the existence of dominant non-local effects in the core of tokamak plasmas, suggesting that the core transport models used to predict burning plasmas in SPARC and ITER would need to be revisited from the ground up. This work demonstrates that the complete behavior of such experiments can be recovered by a fully local turbulent transport model, as long as multi-channel stiff transport is considered. This provides confidence in the predictions of SPARC performance, revealing an ample margin to net fusion gain in a medium-size tokamak.
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Meeting ID: 991 5610 7574
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Meeting ID: 991 5610 7574
- PGSC Professional Development Seminar
- Time: 2:30 pm
- Speaker: Michelle Holland, Physics Graduate Programs Coordinator
- Abstract: Having an outstanding LinkedIn profile may be just the thing that gets you the job. Learn the latest tips and tricks to take your job search presence on LinkedIn to the next level. Join us for an interactive workshop and plan to spend some time polishing your LinkedIn profile. When your dream job comes up, you will be all set and ready to go!
- Host: Michelle Holland, Graduate Program Coordinator
- Network in Neutrinos, Nuclear Astrophysics, and Symmetries (N3AS) Seminar
- Properties of r-Process-Producing Neutron Star Mergers: What We Can Learn from Metal-Poor Stars
- Time: 3:30 pm
- Speaker: Erika Holmbeck , University of Notre Dame
- Host: Baha Balantekin
- Wisconsin Quantum Institute
- CQE Seminar Series: Building the second quantum revolution by training Schrödinger cats, from very fat to very fast
- Time: 11:00 am
- Place: Virtual; contact email@example.com for login info
- Speaker: Tommaso Calarco, Institute for Quantum Control, Peter Grünberg Institute at Forschungszentrum Jülich
- Abstract: Developing quantum technologies towards practical application requires exquisite control of the dynamics of multiqubit systems. Quantum optimal control offers a natural, and increasingly widespread, way to achieve this to the maximum possible extent. I will introduce the optimal control method we developed for quantum many-body systems and its remote closed-loop implementation RedCRAB, and I will report recent results we obtained with it in various physical contexts from diamond color centres to atoms in optical trap arrays, where we demonstrated optimal preparation of a 20-qubit GHZ state as well as single-atom spatial superposition states at the quantum speed limit. I will also put these specific efforts in the more global context of the European Quantum Technologies activities, including recent developments towards scientific cooperation with the US.
- Physics ∩ ML Seminar
- Machine learning as a discovery tool in hep-th
- Time: 11:00 am
- Place: Please sign up at physicsmeetsml.org for this online event.
- Speaker: Vishnu Jejjala, University of Witwatersrand
- Abstract: Machine learning provides a new tool for analyzing Big Data and Small Data in mathematics and theoretical physics. In this talk, I discuss two case studies. The first predicts the volume of the knot complement of hyperbolic knots from the Jones polynomial. The second predicts the masses of baryons such as the proton and neutron from knowledge only of the meson spectrum and distinguishes between different composition hypotheses for exotic QCD resonances. Both investigations point to the existence of new analytic formulae.
- Host: Gary Shiu
- Department Meeting
- Time: 12:15 pm
- Place: Virtual see "abstract" for connection info
- Speaker: Sridhara Dasu, Department Chair, UW-Madison
- Meeting Coordinates: Meeting number: 120 392 9242 Password: Q5EjaTz3Pk3 (75352893 from phones) Join by video system Dial firstname.lastname@example.org You can also dial 22.214.171.124 and enter your meeting number. Join by phone +1-415-655-0001 US Toll +1-312-535-8110 United States Toll (Chicago) Access code: 120 392 9242
- Host: Sridhara Dasu, Department Chair
- Cosmology Journal Club
- Time: 12:00 pm
- Abstract: Cosmology Journal Club is back! We will be having virtual meetings this semester.
Each week, we start with a couple scheduled 15 minute talks about one's research, or an arXiv paper. The last 30 minutes will typically be open to the group for anyone to discuss an arXiv paper.
All are welcome and all fields of cosmology are appropriate.
Contact Ross Cawthon, cawthon@wisc, for more information.
Meeting ID: 93592708053, passcode: cmbadger
- Astronomy Colloquium
- "Particle acceleration by pressure anisotropy plasma instabilities: from black hole accretion disks to solar flares."
- Time: 3:30 pm
- Place: Zoom meeting(see Abstract ) Coffee and tea 3:30pm, Talk 3:45pm
- Speaker: Mario Riquelme, University of Chile
- Abstract: Pressure anisotropies naturally arise in weakly collisional plasmas, and are ultimately limited by the pitch-angle scattering provided by various kinetic plasma instabilities. I will present particle-in-cell (PIC) plasma simulations of these instabilities, and will show that, in some regimes, their scattering can be highly inelastic and produce significant nonthermal particle acceleration. The presentation will focus on two astrophysical plasma environments: i) sub-relativistic, weakly collisional accretion disks around black holes (e.g., Sgr A*), where both electron and ion acceleration will be considered, and ii) non-relativistic, low beta plasmas relevant for solar flares, where the case of electron acceleration will be analyzed. I will review the main evidence for the existence of particle acceleration in these systems, and will discuss the importance that pressure anisotropy instabilities can have in helping explain these fascinating acceleration phenomena.
Meeting ID: 885 1389 6776
- Host: Professor Ellen Zweibel
- Graduate Introductory Seminar (Physics 701)
- Linking the theory and observation of astroparticles
- Time: 12:05 pm
- Place: BBCollaborate
- Speaker: Ke Fang, UW Madison Department of Physics
- Host: Sridhara Dasu
- Theory Seminar (High Energy/Cosmology)
- Gravitational wave probes of axion-like particles
- Time: 2:00 pm
- Place: For zoom link, sign up at:
- Speaker: Ben Stefanek, Mainz Institute for Theoretical Physics
- Abstract: Conventional approaches to probing axions and axion-like particles (ALPs) typically rely on a coupling to photons. However, if this coupling is extremely weak, ALPs become invisible and are effectively decoupled from the Standard Model. Such particles, which are viable candidates for dark matter, can also produce a stochastic gravitational wave (GW) background in the early universe. This occurs if the axion couples to a dark gauge boson that experiences a tachyonic instability when the axion begins to oscillate. This instability exponentially amplifies vacuum fluctuations of a single dark photon helicity, resulting in a rapidly time-varying, anisotropic energy distribution that sources chiral GWs. We identify the regions of ALP parameter space which may be probed by future GW detectors, including ground- and space-based interferometers and pulsar timing arrays. Interestingly, these experiments have the ability to probe axions from the bottom up, i.e. in the very weakly coupled regime which is otherwise unconstrained. A smoking gun for the model is the completely chiral nature of the GW peak, which could be detected by LISA or Einstein Telescope if the signal amplitude is large.
- Host: Lars Aalsma
- Department Coffee Hour
- Time: 3:30 pm
- Abstract: Join us weekly for an informal virtual coffee hour! Catch up with others in the department, tell us how things are going, and impress everyone with your Zoom background skills. Coffee Hour is open to any and all faculty, staff, and students in the department. Sometimes we have a topic, and we'll try to get that topic posted here in advance or sent out by email before each coffee hour.
- Host: Department