Events at Physics |
Events During the Week of April 19th through April 26th, 2015
Monday, April 20th, 2015
- Plasma Physics (Physics/ECE/NE 922) Seminar
- First identification of an Island-induced Alfvén Eigenmode (IAE) on MST
- Time: 12:00 pm - 1:00 pm
- Place: 1610 Engineering Hall
- Speaker: Carson Cook, UW-Madison
- Host: UW
Tuesday, April 21st, 2015
- Chaos & Complex Systems Seminar
- Towards understanding IceCube high energy neutrinos
- Time: 12:05 pm - 1:00 pm
- Place: 4274 Chamberlin Hall (Refreshments will be served)
- Speaker: Yang Bai, UW Department of Physics
- Abstract: The IceCube collaboration has recently observed high energy neutrinos in the 30 TeV to 2 PeV range. The flux is much above the atmospheric neutrino background and requires new sources to explain its origin. In this talk, I will provide a list of potential explanations with a focus on decaying dark matter and point-like sources.
- Host: Clint Sprott
- Theory Seminar (High Energy/Cosmology)
- Perturbative Unitarity Constraints on Dark Sectors
- Time: 4:00 pm - 5:00 pm
- Place: 5280 Chamberlin Hall
- Speaker: Sonia El Hedri
- Abstract: We describe a method that uses perturbative unitarity constraints to find the characteristic energy scales in theories of thermal Dark Matter. We apply this method to three Dark Matter portals: the NMSSM Higgs sector, a Z' model with a dark Higgs, and a squark simplified model, and derive the projected constraints from ton-scale Direct Detection experiments. We briefly describe projected constraints from a 100TeV collider. We also investigate the physical meaning of unitarity bounds on Dark Matter models and how to set more refined bounds on Dark Matter portals
- Host: Ran Lu
Wednesday, April 22nd, 2015
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- Charm jet identification in searches for new physics with the ATLAS detector
- Time: 12:00 pm - 1:00 pm
- Place: 4274 Chamberlin
- Speaker: Dan Guest, Yale University
- Abstract: The first hints of new physics at the LHC may come in the form of extremely short-lived particles which decay instantly to particles in the standard model. These decays could appear as an excess of events in any number of channels. Until recently, searches for such an excess have often neglected decays through charm quarks, owing to the lack of an efficient charm jet identification algorithm.
I will introduce several supersymmetric models where decays through charm quarks are preferred. These searches motivated the development of a lifetime-based charm jet identification algorithm. After discussing this algorithm, I will present the results from two scalar quark searches, where charm jet identification played a central role in extending the previous experimental limits - Host: Stefan Westerhoff
Thursday, April 23rd, 2015
- R. G. Herb Condensed Matter Seminar
- Quantum Spins in Nanostructures: Coherence, Measurement, and Collective Dynamics
- Time: 10:00 am
- Place: 5310 Chamberlin Hall
- Speaker: Bill Coish, McGill University
- Abstract: Qubit coherence measurements are now sufficiently accurate that they can be used to perform 'spectroscopy' of noise due to a complex environment. Measuring not only the decay time, but also the form of decay as a function of some external parameter (e.g. temperature) can determine the nature of the dominant decoherence source. I will describe how temperature-dependent measurements of qubit decoherence time and form of decay can be used to identify microscopic dephasing sources in a semiconductor environment.
I will also briefly discuss some new tricks to enhance the fidelity of generic qubit measurements and prospects for generating and observing genuine collective quantum effects in ensembles of nuclear spins embedded in silicon nanostructures.
- Host: Coppersmith
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- The status of India-based Neutrino Observatory (INO)
- Time: 2:30 pm - 3:30 pm
- Place: 5310 Chamberlin Hall
- Speaker: Bannanje Sripathi Acharya, Tata Institute
- Abstract: In this talk I shall narrate our plans of building a new underground laboratory facility in southern India called India-based neutrino observatory (INO). A 50 kilo-ton magnetised Iron CALorimeter (ICAL)is one of the first experiments proposed to be housed in this observatory for the study of neutrino properties like mass hierarchy, precision measurement of oscillation parameters etc. using the atmospheric neutrinos. The details of this ICAL project and its present status will also be covered in this talk.
- Host: Justin Vandenbrouke
- Astronomy Colloquium
- Gamma-rays from Type Ia supernova SN2014J
- Time: 3:45 pm - 5:00 pm
- Place: 4421 Sterling hall
- Speaker: Eugene Churazov, MPA Garching
- Abstract:
Supernova SN2014J in M82 is the first type Ia supernova, which was close enough to allow robust detection of gamma-ray lines associated with the decay chain Ni56->Co56->Fe56. INTEGRAL observations provide constraints on the total mass of the Ni56 synthesized during explosion, on the released energy, on the mass of the progenitor and on the annihilation of positrons, produced by the Co56 decay. We discuss the implications of these observations for SNIa models and compare results with the predictions of different Type Ia scenarios. Friday, April 24th, 2015
- Cosmology Journal Club
- An Informal discussion about a broad variety of arXiv papers related to Cosmology
- Time: 12:15 pm
- Place: 5242 Chamberlin Hall
- Abstract: Please visit the following link for more details:
http://cmb.physics.wisc.edu/journal/index.html
Please feel free to bring your lunch!
If you have questions or comments about this journal club, would like to propose a topic or volunteer to introduce a paper, please email Le Zhang (lzhang263@wisc.edu) - Host: Peter Timbie
- Physics Department Colloquium
- Universal quake statistics: from nanopillars to earthquakes
- Time: 3:30 pm - 4:30 pm
- Place: 2241 Chamberlin Hall (coffee at 4:30 pm)
- Speaker: Karin Dahmen, University of Illinois
- Abstract: The deformation of many solid materials is not continuous, but discrete, with intermittent slips similar to earthquakes. Here, we suggest that the statistical distributions of the slips, such as the slip-size distributions, reflect tuned criticality, with approximately the same regular (power-law) functions, and the same tunable exponential cutoffs, for systems spanning 13 decades in length, from tens of nanometers to hundreds of kilometers; for compressed nano-crystals, to amorphous materials, ]to earthquakes. The similarities are explained by a simple analytic model, which suggests that results are transferable across scales. This study provides a unified understanding of fundamental properties of shear-induced deformation in systems ranging from nanocrystals to earthquakes. It also provides many new predictions for future experiments and simulations. The studies draw on methods from the theory of phase transitions, the renormalization group, and numerical simulations. Connections to other systems with avalanches, such as magnets and neuron firing avalanches in the brain are also discussed.
- Host: Sue Coppersmith
- Chemistry Department Colloquium
- Scientific Publishing from the Inside Out
- Time: 3:30 pm - 4:30 pm
- Place: 1315 Chemistry Building
- Speaker: Dr. Jake Yeston, Science magazine
- Host: Professor Tehshik Yoon