Events at Physics
Events on Thursday, November 14th, 2013
- R. G. Herb Condensed Matter Seminar
- Universal Features of Counting Statistics of Phase Slips in Superconducting Nanocircuits
- Time: 10:00 am
- Place: Chamberlin 5310
- Speaker: Alex Levchenko, Michigan State University
- Abstract: I will present a systematic study of the statistical properties of switching current distributions deduced from the measurements of phase-slip-induced switching events on different types of superconducting weak links. I will discuss three types of devices in which a weak link is formed either by a superconducting nanowire, a graphene flake subject to proximity effect, or a quantum dot. We demonstrate that independently of the nature of the weak link, higher moments of the distribution take universal values. In particular, the third moment (skewness) of the distribution is close to -1 both in thermal and quantum regimes. The fourth moment (kurtosis) also takes a universal value close to 5. The experimentally discovered universality of the cummulants is confirmed by an analytical model.
- Host: Maxim Vavilov
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- The MicroBooNE and ArgoNeuT Liquid Argon Time Projection Chambers
- Time: 2:30 pm
- Place: 4274 Chamberlin
- Speaker: Jonathan Asaadi, Syracuse
- Abstract: TBLiquid argon time projection chambers (LArTPC's) provide an extraordinary level of information about the interactions of neutrinos. Amongst the several different efforts ongoing at Fermi National Accelerator Laboratory to develop the liquid argon detector technology and utilize it to study neutrino interactions are the MicroBooNE and ArgoNeuT experiments. The MicroBooNE experiment is a 170 ton total mass LArTPC. MicroBooNE will be deployed in the Booster neutrino beam at Fermilab and is scheduled to start taking data in early 2014. The ArgoNeuT experiment deployed a relatively small 0.7 ton total mass LArTPC in the NuMI neutrino beamline at Fermilab, running from September 2009 to February 2010. The data collected is now being analyzed and used to measure neutrino interaction cross-sections. This talk will present an overview of LArTPC's, the current status of the assembly, installation, and operational readiness of the MicroBooNE detector, as well as ongoing analysis from ArgoNeuT data including a look at neutral current pi0 interactions from the NuMI beam.
- Host: Vandenbroucke
- Astronomy Colloquium
- Diagnosing Elliptical Galaxy Formation with Simulations
- Time: 3:30 pm - 5:00 pm
- Place: 4421 Sterling Hall
- Speaker: Greg Snyder, STSci
- Abstract: A challenge in extragalactic astronomy is that we cannot watch what happens to galaxies before and after they are observed. In particular, it remains debated whether galaxy mergers or internal processes drive supermassive black hole growth, trigger luminous starbursts, and shape the population of galaxies we see today. However, given increasingly available computer resources, it is now possible to predict how galaxies might evolve according to a huge variety of observations. With hydrodynamical simulations followed by dust radiative transfer, I examine the formation of elliptical galaxies through three putative phases: dust-obscured starburst, transition object, and red spheroid. I derive an idealized JWST-accessible mid-infrared diagnostic using model spectra from simulations of merger-induced starbursts. I use similar models to reconcile the numbers of optically selected post-starburst galaxies with independent estimates of the galaxy merger rate. To conclude, I describe efforts to build a aEurooemock observatoryaEuro from large-volume cosmological hydrodynamical simulations, with which observations of many types can be brought to bear to constrain the physics of galaxy formation.