Spring 2006 Physics Colloquium Schedule
Unless otherwise noted, the physics colloquia are held in Room 307 of the Science and Engineering Research Facility. Refreshments are served at 3:00 p.m. with the talk following at 3:30. Abstracts are included below the schedule. The ORNL Physics Division Seminar Schedule might also be of interest. Professor John Quinn is chair of the colloquium program. He may be contacted via e-mail at: firstname.lastname@example.org.
Dr. Steven Moszkowski, UCLA
My grandparents were good friends of Albert Einstein in Berlin. Later my parents also were on friendly terms with him. I had the opportunity to meet Einstein four times after my parents and I came to the United States in 1940. My parents and I, on occasion, had correspondence with Einstein and took a few photos of him. Albert Einstein had considerable influence on my development and style of doing physics, as I will discuss.
Dr. C.O. Reinhold, ORNL Physics Division
Manipulation and control of the electronic states of atoms provide an
exciting area of research with important potential applications. Such
control can be achieved using electromagnetic pulses whose strengths are
comparable to the Coulomb electric field, whose durations are of the order
of the classical orbital period of the atom, and whose shapes can be tailored
Dr. Robert Grzywacz, UT Physics
The main thrust in modern day nuclear physics is the study of nuclei with unusual combinations of protons and neutrons. Some of the key questions are: What are the possible particle stable combinations of nucleons? Will a New Order emerge for nuclei with large excesses of either protons or neutrons? What is the effect of the nuclear medium on inter-nucleon interactions? How relevant are properties of the exotic short-lived nuclei to the elemental compostion of our Universe? In recent years, I have conducted research at heavy ion accelerator facilities in the US, France, and Germany, chasing the quickly decaying single ions of the most exotic nuclei. In my talk, I shall explain the challanges of experiments addressing the nature of our world's femtostructures.
Dr. Hanno Weitering, UT Physics
Superconductivity is inevitably suppressed in reduced dimensionality. Questions of how thin superconducting wires or films can be before they lose their superconducting properties have important technological ramifications and go to the heart of understanding coherence and robustness of the superconducting state in quantum-confined geometries. In this talk, I will show how quantum confinement of itinerant electrons in a soft metal, Pb, can be exploited to stabilize superconductors with lateral dimensions of the order of a few millimeters and vertical dimensions of only a few atomic layers. These extremely thin superconductors show no indication of defect- or fluctuation-driven suppression of superconductivity and sustain enormous supercurrents of up to 10% of the theoretical depairing current density. Their magnetic hardness implies a superconducting critical state with strong vortex pinning that is attributed to quantum trapping of vortices. Our study paints a conceptually appealing, elegant picture of a model nanoscale superconductor with calculable critical state properties and surprisingly strong phase coherence. It indicates the intriguing possibility of exploiting robust superconductivity at the nanoscale.
Dr. Daniel Khomskii, University of Cologne
Multiferroics - materials which are simultaneously (ferro)magnetic and ferroelectric, and often also ferroelastic, attract now considerable attention, both because of the interesting physics involved and as they promise important practical applications. In this talk I will give a survey of microscopic factors determining the coexistence of these properties, and will discuss different possible routes to combine them in one material. In particular the role of the occupation of d-states in transition metal perovskites will be discussed, possible role of spiral magnetic structures will be stressed and the novel mechanism of ferroelectricity in magnetic systems due to combination of site-centered and bond-centered charge ordering will be presented. Microscopic nature of multiferroic behavior in several particular materials, including magnetite Fe3O4, will be also discussed.
Dr. Robert Brandenberger, McGill University
In this colloquium I will explain why the inflationary universe scenario, our current paradigm for early universe cosmology, is incomplete, in spite of its phenomenological successes. A better theory of fundamental physics is required to understand the earliest stages in the evolution of the universe - and string theory is a candidate for such a theory. I will explore new cosmological scenarios which emerge from the confluence of string theory and cosmology, models which may not contain a big bang singularity.
Dr. Aron Pinczuk, Columbia University and
Electron fluids in the quantum Hall regimes support low-energy excitation modes that are linked to remarkable behaviors that emerge from fundamental interactions in two-dimensions. Inelastic light scattering methods at very low temperatures (below 1 Kelvin) offer unique experimental venues to study excitations in the charge and spin degrees of freedom of the fluids.
The light scattering experiments access directly low-lying “quasiparticle” excitations above the fluid ground states. These are the excitations that express distinct quantum phases of the electron liquids. This talk presents an overview of recent results that reveal physics of the electron fluids that is not accessible by other methods.
Dr. Russell A. Hulse, 1993 Nobel Prize
Winner, The University of Texas at Dallas and Princeton University Plasma
Pulsars are rapidly rotating neutron stars which are observed using radio
telescopes as pulsed, short-duty-cycle radio sources with typical periods
on the order of 1 second or less. The mechanism underlying this pulsed
emission is analogous to that of a lighthouse beacon, in that the observed
pulses are the result of a tightly beamed pattern of radio radiation from
the star which periodically sweeps across the earth as the star rotates.
In 1974 a high sensitivity search to discover previously unknown pulsars
using the 1000' Arecibo radio telescope discovered 40 new pulsars in our
galaxy, including the 59 ms period pulsar PSR 1913+16. Puzzling and unexpected
variations in the observed pulsation period of this object were ultimately
understood to be the result of doppler shifts associated with the orbital
motion of this pulsar around a companion star. Discovery of this "binary
pulsar" has provided an almost textbook-perfect laboratory for studying
effects predicted by Einstein's theories of relativity, by combining high
orbital velocities and gravitational fields with the measurement capabilities
afforded by use of the pulsar as an extremely precise clock. Continued
high precision observations by Prof. Joseph Taylor and his colleagues
of this orbiting pulsar clock over the 30 years since its discovery have
led to ever more accurate confirmation of these relativistic effects,
including decay of the pulsar's orbit due to the emission of gravitational
Dr. Armand A. Lucas
The ubiquitous and beautiful helical organization of the biological world at the molecular level of DNA , protein alpha-helices , etc... as well as at the mesoscopic scale of viruses , cellular fibers , etc... has been investigated mostly by diffraction methods. More recently Carbon nanotubes were discovered  by high resolution electron microscopy and their detailed atomic structure has again been determined by electron diffraction , . In this lecture I will use optical simulation experiments (the optical transform method) to explain just how X-ray fiber diffraction and electron diffraction have been used to reveal the helical arrangements of DNA and Carbon nanotubes -.
The audience will have the opportunity to take part, hands on, in the optical simulation experiments.
 Franklin R.E. and Gosling R.G., Nature 171, 740, 1953; Watson J.D.
and Crick F.H.C., Nature 171, 737, 1953
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