Events During the Week of May 18th through May 25th, 2025
Sunday, May 18th, 2025
- Academic Calendar
- Faculty contract year ends
- Abstract: *Note: actual end time may vary.*
Monday, May 19th, 2025
- Academic Calendar
- 4-week summer session begins
- Abstract: *Note: actual end time may vary.*
- Thesis Defense
- Nanoscale imaging of viscous and nonlocal transport of electrons in graphene
- Time: 11:00 am - 1:00 pm
- Place: 5310 CH or
- Speaker: Zachary Krebs, Physics PhD Graduate Student
- Abstract: Ballistic and hydrodynamic electron flow can develop in materials when carrier momentum is conserved over long distance and time scales. These non-Ohmic transport regimes are characterized by distinctive spatial distributions of the current density and electrochemical potential. I will show scanning tunneling potentiometry (STP) measurements of the electrochemical potential induced by DC transport in graphene as a function of carrier density, temperature, and magnetic field. First, STP images are recorded as current flows through electrostatic constrictions with gate-tunable width that are "drawn" with the STM tip. The electrochemical potential drop through these constrictions determines the wavevector-dependent conductivity σ(k) of the electron fluid. Upon heating the system from 4.5 K to 77 K, enhanced electron-electron scattering leads to a crossover from ballistic to hydrodynamic flow, identified by super-ballistic conductance through the constrictions and a suppression of Landauer residual resistivity dipoles. When increasing the magnetic field from 0 to 1.4 T at 4.5 K, the STP data reveals a diffusive-to-ballistic crossover in the flow of current resulting from Landau level quantization. In the ballistic regime of magnetotransport, the local Hall field is enhanced one cyclotron diameter away from scattering surfaces.
- Host: Victor Brar
Tuesday, May 20th, 2025
- No events scheduled
Wednesday, May 21st, 2025
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- The Hyper-Kamiokande Project
- Time: 2:30 pm - 3:30 pm
- Place: Chamberlin 5280
- Speaker: Teppei Katori, King's College London
- Abstract: Hyper-Kamiokande project consists with 3 components; Hyper-Kamiokande detector, J-PARC neutrino beam upgrade, and the near detector system. Hyper-Kamiokande detector is the 3rd generation of extremely successful water Cherenkov neutrino detectors at the Kamioka Observatory, Japan (Nobel Prize in Physics, 2002 and 2015). It is a 261 kton water tank with roughly 8 times the fiducial volume of Super-Kamiokande which will help us to push all science to an unprecedented level, including beam-based neutrino physics, astrophysics, and beyond-the-Standard-Model discovery science. In this talk, I will mainly discuss the status of the Hyper-Kamiokande detector construction and R&D.
- Host: Lu Lu
Thursday, May 22nd, 2025
- R. G. Herb Condensed Matter Seminar
- Title to be announced
- Time: 10:00 am
- Place: 5280 Chamberlin Hall
- Speaker: Miguel Morales
- Host: Matthew Otten
- Astronomy Colloquium
- Small-Scale Structure of the "Dark ISM"
- Time: 3:30 pm - 4:30 pm
- Place: 4421 Sterling Hall
- Speaker: Joanne Dawson, Macquarie University
- Abstract: It is now known that a significant fraction of the Milky Way ISM resides in a so-called "dark" phase, usually defined as a mixture of cold, optically thick HI and diffuse molecular hydrogen with densities that are insufficient to form and shield CO. I will present a brief overview of the so-called "Dark ISM" -- where it resides, how much there is, and its characteristic properties. I will then focus on two aspects of structure in the dark gas: (1) AU-scale structures in the cold atomic medium, including their possible implications in measuring the fraction of cold/opaque HI, and (2) underlying structure in CO-dark molecular gas that can give rise to very broad, very weak molecular spectral features in OH and HCO+. I will introduce two ongoing observational experiments that may further constrain both of these phenomena.
- Host: Snezana Stanimirovic
Friday, May 23rd, 2025
- No events scheduled