This site will look much better in a browser that supports web standards, but it is accessible to any browser or Internet device.
Skip Navigation skip menu and banner
University of Wyoming

University of Wyoming Physics & Astronomy Colloquium Series

Fridays -- 4:10 PM -- Prowse Room 234

Pre-Colloquium tea served at 3:45 in the Cinnamon Room, PS 237

Fall 2008 & Spring 2009 Schedule

Sep19 Michael Shull (University of Colorado)
Baryons and Metals in the low-redshift Intergalactic Medium and Galactic Halo

Far-ultraviolet spectra of quasars and other active galaxies from the Hubble Space Telescope (HST) and Far-Ultraviolet Spectroscopic Explorer (FUSE) have allowed astronomers to probe baryons and heavy elements in the low-redshift intergalactic medium (IGM) as well as the Galactic halo. These UV surveys have identified approximately half the baryons inferred from Big Bang nucleosynthesis and the Cosmic Microwave Background, in the form of diffuse Lya absorbers and hot ionized gas (O VI). This OVI-bearing gas, at temperatures of 10^5 to 10^6 K, may be produced by shocks during the formation of large-scale structure and by powerful galactic outflows. The Cosmic Origins Spectrograph (COS) to be installed on HST in Oct 2008 will probe the IGM content and evolution out to redshift z = 1. Our key science includes studies of missing baryons, metal evolution and transport, intervening galaxy halos, and cosmology, with over 10^4 Lya absorbers and corresponding metal lines at low redshift.

Oct 1 Christ Ftaclas (U. Hawaii)
Adaptive Optics in a Shoebox
Oct 17 John Feldmeier (Youngstown State)
Intracluster light in Virgo and Other Galaxy Clusters

Intracluster stars, stars between the galaxies in a galaxy cluster, are a sensitive probe of galaxy and galaxy cluster evolution. For the past few years, we have observed intracluster light using deep imaging and finding luminous tracers of the intracluster light. We have found that the intracluster light is a common component of galaxy clusters (10-20% of the total starlight), and is spatially distributed due to its tidal origin. Future projects, including observations at WIRO, will also be discussed.

Nov 21 Barry Zink (University of Denver)
Electron, Phonon, and Magnon Heat Transport in Thin Films and Nanostructures

A wide range of experimental and theoretical tools have been used to explore the exciting regime where one or more of the physical dimensions of a condensed matter sample is reduced below 100 nanometers. Such tiny systems exhibit dramatic effects in electrical transport, including the well-known phenomenon of quantized conductance. By comparison the fundamentals of thermal transport in nanoscale systems are less well known, primarily due to the difficulty of measuring thermal properties of thin films and nanowires. This talk will briefly introduce the challenges of thermal measurements of small samples, consider the fascinating physics of such systems, and describe our current work toward a new understanding of heat transport in metallic, semiconducting, and magnetic thin films and nanowires made possible by direct measurements of thermal, electronic, and thermoelectric transport. These measurements are enabled by micro- or nanomachined thermal isolation platforms that integrate sensitive thin-film heaters and thermometers. The resulting fundamental knowledge could advance technologies ranging from thermoelectric energy generators to magnetic logic devices.

Nov 24 Li Yang (UC Berkeley)
Electronic Structure and Optical Response of Low-dimensional Materials - from Nanowires, Nanoribbons to Graphene


Dec 2 Adrian Feiguin (UC Santa Barbara)
Coherent dynamics of a single spin in diamond

Diamond is cool ... literally. We know a lot about diamond: it has virtually no magnetism, it does not conduct electricity, and it is the hardest material known to man. It is precisely because of all of these properties that it makes the perfect environment to store quantum information: it is "cold", even at room temperature, and an impurity embedded in its crystalline structure is almost perfectly shielded from the environment. Nitrogen is one of the most common impurities in diamond, where it replaces a carbon atom in the crystal. Some of these impurities tend to pair with vacancies, forming what is known as an NV center. These NV centers have total spin S=1, and can be used as qubits for quantum information processing. They can be initialized, manipulated, and read out with very high fidelity, and long coherence times, even at room temperature. But in the case of "dirty" diamond, where impurities abound, we find that it can be used to realize an almost ideal case of a very old theoretical problem: the "central spin problem", with a spin embedded in a spin bath. Moreover, the dynamics of the spin bath can be tuned at will, using an external magnetic field. In this talk, I will describe recent exciting developments for using diamond for quantum information processing, and how a successful combination of theory, experiment, and computer simulations has lead to a deep understanding of the processes that contribute to the spin decoherence. In particular, I will discuss the curious case of Rabi oscillations, that show a collapse and revival feature that cannot be explained without taking into account the hyperfine structure of NV centers. By numerically simulating a model obtained from first principles, we show that experiments can be interpreted as a quantum interference effect.

Dec 5 at 2:30 Peter Dowben (U. Nebraska)
The History and Development of Boron Carbon Alloy Devices and Rare Earth Heterojunction Neutron Detectors

Traditional neutron detectors have been large, delicate, cumbersome and expensive, with high power requirements. A SOLID STATE neutron detector would overcome many of these problems. We believe that there are neutron detector technologies, developed at the University of Nebraska, the University of Wyoming and elsewhere, that can be substantially improved, possibly outclassing all other competing technologies for the monitoring and detecting of fissile and other neutron emitting radioactive materials in terms of expense of manufacture, device lifetime and power consumption. These technologies are based on the development of novel semiconductor materials, based on boron and/or gadolinium to make neutron detectors. The breakthroughs thus far result from incorporation the boron or gadolinium into the active part of the semiconductor device itself, rather than as a separate layer solely for the purpose of capturing the neutrons.

Jan 30 Ginny McSwain (Lehigh University)
The Great Escape: A Tale of Runaway Binary Stars and Their Evolution

Abstract: Runaway stars are ejected from the cluster of their birth either by gravitational interactions or a supernova in a close binary system. While runaway binaries are rare, these systems offer key insights into the evolution of close binary stars and open clusters. I will present a combination of radio, optical, ultraviolet, and X-ray data for three runaway binaries that reveal clues about their origins. One system, LS 5039, was clearly ejected by a supernova because the neutron star remains gravitationally bound to the star. In addition, I will discuss evidence for and against both ejection mechanisms in the runaway binaries HD 14633 and HD 15137.

Feb 27 Chris Howk (Notre Dame)
On the importance of Outflows and Infall in Spiral Galaxies: Interstellar Dust as a Probe of Galaxy Assembly

Dust is a minor constituent of the interstellar medium by mass, but has disproportionate effects on the thermal balance of the ISM, on the distribution of relative abundances of metals, and on the propagation of UV photons. A decade and more of observations have demonstrated that dust is an important tracer of extraplanar material in spiral galaxies. Most theories for the origin of the extraplanar dust argue for its expulsion from the disk, requiring the dust to be relatively robust to destruction during this process. However, all modern models of galaxy evolution require on-going infall of pristine gas to explain the metallicity distribution of stars in the Milky Way and, more fundamentally, the fact that galaxies have formed stars over many Gigayears even though their gas consumption times should be much shorter. I will discuss how multiwavelength observations of extraplanar dust may weigh on the mixture of "outflow versus infall" sources for thick disk and halo in nearby galaxies. I will discuss observational probes of extraplanar dust and will comment on the physical conditions of the material implied by the observations. I will discuss the origins of such dust and the implications for the origins of thick disk and halo gas.

March 6 Chiao-Yao She (Colorado State)
Challenges and Payoffs of Observing Upper Atmosphere with Laser Induced Fluorescence

In this talk, I will first briefly discuss the thermal structure of atmospheric layers, pointing out their mutual influences as a small but important part of solar terrestrial relations. I will then explain the counter-intuitive climate of warmer winter and cooler summer in the upper atmosphere, or in the mesosphere and lower thermosphere (MLT), and illustrate the importance of temperature and wind measurements to unlock the secret linking the troposphere and the lower thermosphere. I will then review the physics of lidar techniques and discuss the use of laser induced fluorescence spectroscopy from natural sodium atoms in the sky for measuring temperature and winds in the mesopause region (80 - 110 km). Using examples selected from our research with Na lidar in the MLT in the past decade, I hope to demonstrate how lidar observations can be employed to help resolving outstanding science questions, engaging leading dynamicists, thus making significant impact on the relevant science and on the General Circulation Models. I will explain all these physically without equations beyond those in a Freshman Physics text.

March 20 Spring Break

March 25 Antonio Bianchini (University of Padova)
An Introduction to Cataclysmic Variables

The basic phenomenological and physical characteristics of Cataclysmic Variables (CVs) are reviewed. The most popular sub-classes of CVs are Novae, Dwarf-Novae and Symbiotics, all of them presenting quite a variety of peculiar behaviours. CVs are privileged laboratories where we can study many basic physical processes like accretion on magnetic collapsed objects and the properties of the MHD flows, the formation of stellar dynamos in the convective layers of the solar type secondaries and the conditions for TNRs within degenerate matter. CVs also provide important information about stellar evolution. In particular, some Novae and Symbiotic stars might be progenitors of SN Ia. Many aspects of the phenomenologies observed are still poorly understood, but this makes CVs even more intriguing subjects for astrophysical research.

April 10 Pat Kohl (Colorado School of Mines)
Making the traditional-to-Studio transformation in the Colorado School of Mines physics department

In the fall of 2007, we converted our second-semester introductory physics course (Physics 200) from a traditional lecture/lab/recitation format to a hybrid lecture/Studio format. In this talk, we will have two main goals. First, we will discuss the opportunities and design decisions that made Studio possible. This will include the format and curriculum choices we made to keep the time and resource investments manageable during the transition. Second, we will discuss the Physics Education Research (PER)-based changes we have made to our course in the process of matching it to the Studio environment, as well as the assessment tools we are using to monitor the course.

April 24 Mike Strutskie (Virginia)
Big Astronomy with Small Telescopes: A Quarter-century of Infrared Science and Student Training on < 1-meter Apertures Uniquely instrumented small telescopes (1-meter or smaller) provide ideal platforms for student training and niche research impractical at larger aperture facilities. Near-infrared imaging and spectroscopy is particularly attractive in this regard given the immunity to water vapor opacity at the YJHK band centers - even at low-altitude "wet" observing sites. In this talk I will cameo a variety of small-telescope instrument and science enterprises, past and present, that illuminate the practical advantages of such small-telescope opportunities, as well as ways in which small telescope observing can bootstrap bigger science.

Previous colloquia series: Fall 2002 Spring 2003 Fall 2003 Spring 2004 Fall 2004 Spring 2005 Fall 2005 Spring 2006 Fall 2006 Spring 2007 Fall 2007
Spring 2008
Contact for program information: Chip Kobulnicky