Schedule Spring 2012
Tuesday January 17, 2012
Dr. Renee Fatemi
University of Kentucky
"Deconstructing the Partonic Origins of the Proton Spin"
The discovery of quarks in the 1960's launched a now classic question in nuclear physics: How do the interactions between quarks and gluons produce the fundamental properties of the proton and neutron? The nucleon electric charge is simply the sum of the valence quark charges, while the mass is largely due to the energy stored in the color fields or gluons. In contrast, it is not yet understood how the spin and orbital angular momentum of three valence quarks and a nearly infinite number of gluons and sea quarks combine to produce a spin 1/2 nucleon. Inclusive deep inelastic scattering experiments have limited the valence + sea quark contribution to less than a third of the total nucleon helicity distribution. Alternative measurements and techniques, currently being pursued in experiments worldwide, are needed to provide precision insights into the gluon spin, the flavor separated quark spin and the partonic orbital momenta contributions. This talk will present the most recent experimental contributions to these goals from the STAR spin program at the Relativistic Heavy Ion Collider.
Tuesday January 24, 2012
Dr. Efstratios Manousakis
Florida State University
"Mathematical Description of the Operation of Consciousness: When Perceptual Time Stands Still "
A mathematical formalism is sought to describe the subjective (first-person experience) or abstract/mental process of perception by examining the general character and operation of the process of perception. This formalism should describe the psycho-physical dynamics of the subjective or cognitive experience as communicated to us by the subject. By making some simple observations of the nature of awareness as we all experience it, we derive a formalism to describe basic aspects of the first-person experience of perception, which exactly parallels the structure of quantum mechanics. Namely, we find that the formalism of orthodox quantum theory of measurement, where the observer plays a key role, may be a broader mathematical foundation which can be adopted to describe the dynamics of the subjective experience. Subsequently, the formalism is used to describe simple perception processes and, in particular, to describe the probability distribution of dominance duration (PDDD) obtained from the testimony of subjects experiencing binocular rivalry. Using this theory and parameters based on known values of neuronal oscillation frequencies and firing rates, the calculated PDDD of rival states in binocular rivalry under various conditions is found to be in good agreement with available experimental data. Motivated by this theory, we carried out binocular rivalry experiments with a large number of subjects to obtain high quality statistics on PDDD for the case where the rival stimulus is periodically removed to test detailed counter-intuitive predictions of this theory. The data and the theoretical predictions are in very good agreement using no adjustable parameters.
The audience is not required to have any prior knowledge of these phenomena as they will be illustrated during the talk.
Tuesday January 31, 2012
Dr. Phil Johnson
"Quantum Collapse and Revival of Ultracold Atoms in Optical Lattices"
An optical lattice is a force field of light created by counter-propagating laser beams which can suspend arrays of ultracold atoms much like eggs are held in an egg carton. It is possible to load lattices with equilibrium states where single atoms occupy distinct wells, or where atoms behave collectively like a superfluid and, in some sense, occupy many lattice wells simultaneously. I will describe our investigations of the dynamics of even stranger nonequilibrium states of atoms which oscillate in time between being a superfluid and an incoherent classical gas. Our studies reveal universal properties of low-energy interactions between trapped bosons, and also probe the cross-over between quantum and classical physics. Finally, I will also describe our efforts toward designing new types of quantum sensors based on the nonlinear dynamics of ultracold atoms trapped in lattices.
Tuesday February 21, 2012
Dr. Rolf Ent
"Studies of the Building Blocks of Atomic Nuclei and the Onset of the Quark Parton Model "
The quarks and gluons of QCD are hidden. At high energies the property of QCD known as asymptotic freedom, which causes quarks to interact very weakly at short distances, allows for an efficient perturbative description of the interior landscape of nucleons in terms of a sea of quarks and gluons with a few ever-present valence quarks. In contrast, protons and neutrons that are the constituents of nuclei are identified with color singlet states that have strong interactions very different from that of the gluon exchange by colored quarks and gluons. Protons and neutrons rather seem bound together by the exchange of evanescent mesons at distance scales comparable to their sizes (~1 fm). Despite this apparent dichotomy, a striking similarity between data measured at high and low energies is observed. As a corollary, the quark parton model, developed to describe high-energy scattering data, has been found to be remarkably successful in also describing data at relatively modest energies of order 5 GeV. With the 12-GeV Jefferson Lab Upgrade, this will then in turn allow for a rich field of investigations of the underlying quark-gluon description of the building blocks of atomic nuclei.
Tuesday February 28, 2012
Dr. Alexey Yamilov
Department of Physics
Missouri University of Science and Technology
"Mesoscopic Optics or: How I Learned to Stop Worrying and love the (Photonic) Bomb"
The term mesoscopic physics refers to a wide range of quantum interference phenomena which occur in solids between macroscopic and microscopic size. Quantum or not, the interference phenomena are common to waves of any nature, including the electromagnetic waves. We will explore the similarities and differences between mesoscopic electronic transport and the light propagation in inhomogeneous media. For example, bosonic nature of photons offers an exciting possibility of coherent amplification which adds a new dimension to the fundamental study of mesoscopic transport and leads to an altogether new physical phenomenon â€" random lasing. This is only one of many examples of how abandoning common perception of inhomogeneities as a nuisance can lead to novel optical phenomena with very practical applications â€" the realm of mesoscopic optics.
Tuesday March 27, 2012
Dr. Frank Narducci
"Successful Publishing in Physical Review letters/The Physical Review"
What happens to your manuscript when you submit it to Physical Review Letters/The Physical Review? In this talk, I will open this black box and discuss the general editorial process that leads to the publication (or rejection) of a manuscript submitted to Physical Review Letters/The Physical Review. In a humorous atmosphere, Iâ€™ll present the â€œdos and donâ€™tsâ€ associated with publishing in the APS journals, starting from the initial submission to our appeals process. Statistics associated with the journal will be presented (but kept to a minimum!) Finally, Iâ€™ll present our recent initiatives, ranging from raising the standards in PRL to Physics and Physics X.
Tuesday April 10, 2012
Dr. Zhirong Huang
Tuesday April 17, 2012
Dr. Daniel K. Havey
Department of Chemistry and Biochemistry
James Madison University
"Impact of Water-Broadening on Atmospheric Remote Sensing of Carbon Dioxide"
Remote sensing of CO2, an important greenhouse gas, requires high-fidelity reference data of spectral line parameters to be successful. In order to accurately determine columnintegrated concentrations of CO2, satellite missions typically rely on optical spectra of both CO2 and O2. Measurements of O2 are important because its concentration is uniform and well-mixed in the atmosphere. Subsequently, measuring O2 remotely allows determination of atmospheric path lengths. One potential source of bias in remote sensing missions aiming to measure CO2 is the influence of H2O on the spectra of O2 and/or CO2. Water makes up approximately 1-4% of Earthâ€™s lower atmosphere and can interfere with remote sensing measurements by (1) appearing as a direct spectral interference or (2) acting as a foreign broadener for CO2 and/or O2 lines. Recent work by our group will be discussed which quantify water-broadening of CO2 and O2 with modest uncertainty. Neglecting to include our results in retrieval algorithms will result in a complicated spatially and seasonally variable measurement bias. The planned colloquium will move through the basics of atmospheric remote sensing, discuss current measurement needs and challenges, explain research results, and convey the atmospheric implications of those results.
Senior Thesis Presentations