Events at Physics |
Events During the Week of November 13th through November 19th, 2016
Monday, November 14th, 2016
- Plasma Physics (Physics/ECE/NE 922) Seminar
- Continuum-kinetic approach to sheath simulations
- Time: 12:00 pm - 1:00 pm
- Place: 2241 Chamberlin Hall
- Speaker: Bhuvana Srinavasan, Virginia Tech
- Abstract: When plasma interacts with a surface, a plasma sheath forms at the
interface, which is typically a region of net positive space charge. Ions, accelerated by the electric field in the sheath region, and hot electrons are known to cause emission from the surface. This can have consequences for devices such as Hall thrusters as electron emissions can increase the rate of erosion of the electrodes affecting performance and longevity of the thrusters – an important concern for space-bound missions. The length-scale of sheaths is small in comparison to the undisturbed plasma (on order of the Debye length)yet the sheath has a global effect on plasma and needs to be included self-consistently in computer simulations. This usually means resolving the Debye length and the plasma oscillation frequency, which makes global and complex simulations extremely demanding in terms of the computational cost. Simulations of classical sheaths using a continuum kinetic model are presented where we directly solve the
Boltzmann equation for each of the ion and electron species using the discontinuous Galerkin method. - Host: Carl Sovinec
- Graduate Introductory Seminar
- Plasma Physics
- Time: 5:30 pm - 6:30 pm
- Place: 5280 Chamberlin hall
- Speaker: Boldyrev, Den Hartog, Egedal, Forest, Sarff, Terry, Zweibel
Tuesday, November 15th, 2016
- Chaos & Complex Systems Seminar
- Macro-evolution: A new model emerging from modern genome data
- Time: 12:05 pm - 1:00 pm
- Place: 4274 Chamberlin (refreshments will be served)
- Speaker: Periannan Senapathy, Genome International Corporation
- Abstract: Origin of life is an unsolved phenomenon. Charles Darwin’s mechanism assumes a universal ancestor, and elaborates the natural selection model to show how this ancestor could have evolved into all other organisms on earth, thus leaving the question open. While it has been known that natural selection mechanisms are able to clearly explain the “micro-evolution" of an organism into its varieties (for example, a crab into many different crab varieties), natural selection is unable to explain how an organism, such as a worm, could evolve into an entirely distinct organism such as a crab (termed "macro-evolution"). In this context, a theory formulated by Senapathy, that complex organisms could arise directly in prebiotic chemistry based on the easy origin of split genes in prebiotic random DNA, offers an explanation for macroevolution. This model shows that the genomes of complex organisms based on split genes are easy to arise from prebiotic chemistry, whereas the genomes of the apparently "simple" bacterial organisms could not. The implications of this model contrasting the conventional model will be discussed.
- Host: Clint Sprott
- Council Meeting
- Time: 1:00 pm - 2:00 pm
- Place: 5290 Chamberlin hall
- Speaker: Albrecht Karle
- Theory Seminar (High Energy/Cosmology)
- Lighting Up Collider Searches for Electroweak States
- Time: 3:30 pm
- Place: 5280 Chamberlin
- Speaker: Ahmed Ismail, University of Pittsburgh
- Abstract: Despite appearing in many extensions of the Standard Model, uncolored electroweak particles face limited collider search prospects. For nearly degenerate electroweak multiplets where the lightest state is electrically neutral, searches typically rely on pair production of the new states in association with visible radiation, e.g. the mono-X final state. We show that for such new particles, considering final state photon radiation can provide increased sensitivity. The additional kinematical information provided by including final state electromagnetic radiation more than compensates for the reduced statistics.
- Host: Joshua Berger
Wednesday, November 16th, 2016
- Department Meeting
- **CANCELLED**
- Time: 12:15 pm
- Place: 5310 Chamberlin hall
- Speaker: Albrecht Karle
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- Multi-Messenger Astronomy with Neutrinos
- Time: 2:30 pm - 3:30 pm
- Place: 5280 Chamberlin Hall (coffee)
- Speaker: Anna Franckowiak, DESY, Germany
- Abstract: The recent discovery of high-energy astrophysical neutrinos has opened a new window to the Universe. However, the sources of those neutrinos are still unknown. Among the plausible candidates are active galactic nuclei, gamma-ray bursts and supernovae. Combining neutrino data with electromagnetic measurements in a multi-messenger approach will increase the sensitivity to identify the neutrino sources and help to solve long-standing problems in astrophysics such as the origin of cosmic rays.
I will review the recent progress in multi-messenger astronomy using neutrino data. - Host: Albrecht Karle
- PUBLIC BAUTZ LECTURE AT WID BY EVA GREBEL
- Galactic Archeology
- Time: 5:00 pm - 6:00 am
- Place: Hector Deluca Forum Room, Wisconsin Institutes for Discovery
- Speaker: Eva Grebel, University of Heidelberg
- Abstract: How did galaxies in the universe evolve with cosmic time? Astronomers address this issue in part by observing the faint light from distant, young galaxies and in part by exploring the details preserved by stars of different ages in nearby galaxies. Professor Grebel will take us on a cosmic journey that reveals a continuously changing universe where galaxies are not viewed as isolated "island universe" but rather as gregarious systems that evolve through interactions with their neighbors. Even our own Milky Way has cannibalized some of its smaller companions, and in the distant future our Galaxy will collide with the closest neighboring spiral, the Andromeda galaxy.
- Host: Astronomy department Pat Bautz Lecturer
Thursday, November 17th, 2016
- R. G. Herb Condensed Matter Seminar
- Measurement of superconducting qubits
- Time: 10:00 am
- Place: 5310 Chamberlin
- Speaker: Mostafa Khezri , UC Riverside
- Abstract: Superconducting qubits are among the most promising candidates for building a quantum computer. In this talk, we discuss measurement of their most popular flavor, the transmon qubit. In particular, we address the effect of the neighboring qubits on measurement fidelity, introduce dressed squeezed state as an approximation of the joint state of the qubit-resonator system, and also show that non-RWA couplings lead to abrupt qubit state deterioration with increasing measurement microwave power.
- Host: Vavilov
- Cosmology Journal Club
- An Informal discussion about a broad variety of arXiv papers related to Cosmology
- Time: 12:15 pm - 1:15 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 Amol Upadhye (aupadhye@wisc.edu). - Host: Amol Upadhye
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- A novel on-chip, mm-wavelength spectrometer for mapping the high-redshift universe.
- Time: 2:30 pm - 3:30 pm
- Place: 5280 Chamberlin Hall
- Speaker: Erik Shirokoff, University of Chicago
- Abstract: Title: A novel on-chip, mm-wavelength spectrometer for mapping the high-redshift universe.
SuperSpec is an compact on-chip spectrometer for mm and submm wavelength astronomy. Its small size, wide spectral bandwidth, and highly multiplexed detector readout will enable construction of powerful multi-object spectrometers for high-redshift observations. The design employs a filter bank consisting of a series of superconducting thin film circuit elements, each coupled to titanium nitride lumped-element kinetic inductance detector (KID.) I will discuss the design, optimization, and measured performance of our prototype devices, our upcoming observing run with the SuperSpec demonstration camera, and the observations that will become possible with a large multi-object-spectrometer based upon this technology. These future instruments will allow us to characterize thousands of high redshift dusty star forming galaxies and to measure to characterize star formation during the epoch of reionization through tomographic intensity mapping. - Host: Peter Timbie
- Astronomy Colloquium
- Bautz Lecture
- Dwarf Galaxies: Fossils of Galaxy Evolution
- Time: 3:30 pm - 5:00 pm
- Place: 4421 Sterling Hall, Coffee and Cookies 3:30 pm, Talk starts at 3:45 pm
- Speaker: Professor Eva Grebel, Bautz Lecturer, University of Heidelberg
- Abstract: "Dwarf galaxies are the most common type of galaxy in the Universe and include the most dark-matter-dominated objects known. They offer intriguing insights into evolutionary processes at low halo masses and low metallicities. Moreover, as survivors of a once much more numerous population of building blocks of larger galaxies, they are key to understanding very early star formation processes. The Local Group and particularly the Milky Way's dwarf galaxy entourage offer us the unique possibility to compare in detail dwarf and Galactic populations. This is an important step towards quantifying the magnitude and time scales of dwarf contributions to the build-up of the Milky Way and allows us to test predictions of cosmological theories and hierarchical structure formation."
Friday, November 18th, 2016
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- The Fermi view of Gamma-Ray Bursts & the curious case of GW 150914
- Time: 2:00 pm
- Place: 5280 Chamberlin Hall
- Speaker: Elisabetta Bissaldi , Politecnico & INFN Bari
- Abstract: I'll give a brief overview of Gamma-Ray Bursts (GRBs) observations performed over the past 8 years by the two instruments on-board the Fermi satellite, namely the Gamma-Ray Burst Monitor (GBM) and the Large Area Telescope (LAT).<br><br>
In this period of time, GBM has triggered and located on average approximately two GRBs every three days. The most recent results are summarized in the latest two catalogs provided by the Fermi GBM science team, namely the third GBM GRB catalog and the first GBM time-resolved spectral catalog.<br><br>
Moreover, the Fermi LAT science team has been recently performing an extensive search for GRBs at high energies (>100 MeV) featuring a detection efficiency more than 50% better than previous works, and returning more than 130 detections.<br><br>
Finally, I'll present the GBM and LAT follow-up of the LIGO Gravitational Wave event GW 150914, focusing on the GBM detection of a weak transient event, close in time to the LIGO one. Future joint observations of GW events by LIGO/Virgo and Fermi could reveal whether the weak transient reported by GBM is a plausible counterpart to GW150914 or a chance coincidence, and will further probe the connection between compact binary mergers and short GRBs. - Host: Justin Vandenbroucke
- Physics Department Colloquium
- Countdown to Solar Probe
- Time: 3:30 pm
- Place: 2241 Chamberlin hall
- Speaker: Justin Kasper, University of Michigan
- Abstract: Less than two years from now we will make history by dropping the first instrumented probe into the extended atmosphere of the Sun to directly observe the extreme environment responsible for superheating the solar corona and accelerating the solar wind. For centuries solar eclipses have provided brief glimpses of the solar corona, the remarkably structured atmosphere that surrounds the Sun and spreads through interplanetary space as the solar wind. Today, the Sun and the corona are tracked continuously by observatories on Earth and in space. We know much more about solar activity and the impact space weather can have on society than ever before, but we have not been able to answer fundamental questions about the Sun. Why is the corona millions of degrees hotter than the visible surface of the Sun? How does the corona drive a supersonic solar wind? How are solar flares and eruptions able to produce storms of radiation? It has long been recognized that the only way to unambiguously answer these questions is to send an instrumented probe close to the Sun. In 2018 we will finally embark on this journey with the Solar Probe Plus spacecraft, a NASA mission that will repeatedly plunge through the corona to obtain the first direct samples of the Sun. The mission will be reviewed, with a focus on the physics of the solar corona and the design of plasma instruments capable of both making the necessary measurements and of surviving the solar encounters.
- Host: Cary Forest
