Spring 2011 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.
The ORNL Physics Division Seminar Schedule and the UTK Math Department Seminar Calendar might also be of interest.
Physics Colloquium Webcasts: Current Year
Physics Colloquium Webcasts Archive
| Date | Speaker and Title |
|---|---|
| January 24 | Kaladi S. Babu Department of Physics Oklahoma State University "Baryon Number Violation, Neutrino Oscillation, and the Path to Unification" [.pdf of presentation] |
| January 31 | Chuck Horowitz Indiana University "Neutron Rich Matter, Neutron Stars, and their Crusts" |
| February 7 | Itamar Arel UTK Department of Electrical Engineering and Computer Science "Reinforcement Learning: Past, Present and Future" |
| February 14 | Kit H. Bowen Johns Hopkins University "Negative Ion Photoelectron (Photodetachment) Spectroscopy of Cluster Anions" |
| February 21 | Doug Scalapino UCSB "A Common Thread" |
| February 28 | Jeff Moersch UTK Earth and Planetary Sciences "Prospecting for Water with Rovers on Mars" |
| March 7 | Karol Lang University of Texas, Austin "Neutrino Physics without Neutrinos: A Search for Neutrinoless Double Beta Decay" |
| March 14 | Spring Break: No Colloquium |
| March 21 | APS Eirik Endeve Oak Ridge National Laboratory "Simulations of Core-Collapse Supernovae with GenASiS" |
| March 28 | Konstantinos Orginos College of William and Mary "Lattice Gauge Theory" |
| April 4 | David Mandrus UTK Materials Science and Engineering "The Indispensible Role of New Materials in Condensed Matter Physics" |
| April 11 | Tom Handler UTK Physics and Astronomy "Science and Public Policy" |
| April 18 | Pedro Marronetti Florida Atlantic University "Black Holes Collide: Interactions between the Simplest Objects in the Universe" |
| April 25 | Honors Day Celebration |
Abstracts
January 24, 2011
Kaladi S. Babu, Department of Physics, Oklahoma State University
"Baryon Number Violation, Neutrino Oscillation, and the Path to Unification"
In this talk, I will first review the motivations for "grand unification" of forces and the experimental hints in its support. Then I will describe recent progress in model building based on a class of supersymmetric gauge theories. Small neutrino masses leading to neutrino flavor oscillations is a natural outcome of these theories. Expectations for neutrino oscillation parameters and for the quark masses and mixing angles will be outlined. A hallmark prediction of grand unified theories is the violation of baryon number and matter instability. Proton must decay with a lifetime accessible to experiments. Neutron may oscillate into anti-neutron with a lifetime reachable in proposed experiments. A possible link between neutron--anti-neutron oscillations and the cosmological baryon asymmetry will be discussed. Experiments at the Large Hadron Collider can shed light on various aspects of grand unification, which will be outlined.
January 31, 2011
Chuck Horowitz, Indiana University
"Neutron Rich Matter, Neutron Stars, and Their Crusts"
Compress almost anything to great densities and electrons react with protons to make neutron rich matter. This material is at the heart of many fundamental questions in Nuclear Physics and Astrophysics. What are the high-density phases of Quantum Chromodynamics (our theory of quarks and gluons)? Where did the chemical elements come from? What is the structure of many compact and energetic objects in the heavens, and what determines their electromagnetic, neutrino, and gravitational-wave radiations? Moreover, neutron rich matter is being studied with an extraordinary variety of new tools such as Facility for Rare Isotope Beams (FRIB), an accelerator that is being built at Michigan State University, and the Laser Interferometer Gravitational Wave Observatory (LIGO). We describe the Lead Radius Experiment (PREX) that is using parity violating electron scattering to measure the neutron radius in 208Pb. This has important implications for neutron rich matter, neutron stars, and their crusts. We model neutron rich matter using large-scale molecular dynamics simulations. We find neutron star crust to be the strongest material known, some 10 billion times stronger than steel. It can support large mountains. These concentrated masses, on rapidly rotating stars, can generate detectable oscillations of space and time known as gravitational waves.
February 7, 2011
Itamar Arel, UTK Department of Electrical Engineering and Computer Science
"Reinforcement Learning: Past, Present and Future"
Reinforcement learning (RL) addresses the problem of learning optimal policies in sequential decision-making problems involving uncertainty, primarily due to stochastic environments and/or reward functions. This stands in contrast to the more traditional logical goal predicates. In many ways, reinforcement learning research is recapitulating the development of classical research in planning and problem solving. Recent neuroscience findings seem to support the underlying principles of RL as a potential framework for the design of intelligent systems. In this talk, I will provide an overview of key results in reinforcement learning as well as outline future directions in which it can be broadened to address large-scale problems, particularly those imposed by artificial general intelligence.
February 14, 2011
Kit H. Bowen,
Johns Hopkins University
"Negative Ion Photoelectron (Photodetachment) Spectroscopy of Cluster Anions"
Negative ion photoelectron spectroscopy is a technique which provides information about both the electrophilic properties (electron affinities) and the vibrational and electronic structure of molecules and clusters (aggregates). It accomplishes this by photdetaching electrons from well-characterized beams of their negative ions. Our objective in using this technique to study clusters is to contribute to a microscopic description of incipient condensed phase phenomena, many of which have no true molecular level counterparts. Using this method, we have studied cluster anion systems which are relevant to bio-physics, solvation phenomena and electron-induced reactivity in chemistry, the kernels of new materials, and issues at the edge of condensed matter physics. Today, I will highlight our results dealing with metal-insulator transitions in clusters, electron-induced proton transfer in acid-base reactions, the discovery of new classes of aluminum hydrides, and solvent-induced transformations of dipole bound anions into valence anion states.
February 21, 2011
Douglas Scalapino,
University of California, Santa Barbara
"A Common Thread"
There are common material, experimental and theoretical threads linking the heavy fermion, cuprate and Fe superconductors. The materials come in families which contain quasi-2D layers of correlated d or f electrons. Their temperature-doping and magnetic field phase diagrams show antiferromag- netism in close proximity to superconductivity. They exhibit quantum crit- ical behavior. The resonant peak observed in inelastic neutron scattering experiments in the superconducting phase provide a signature for an un- conventional gap Δ(k + Q) = -Δ(k). This resonance also implies that the same electrons are involved in both the magnetism and the supercon- ductivity. Single- and multi-band Hubbard models exhibit a number of the properties seen in these materials. Numerical studies of the effective pair- ing interaction in the single-band Hubbard model and various weak coupling calculations on multi-band models find unconventional pairing mediated by an S = 1 particle-hole channel. Thus while the heavy fermion, cuprate and Fe-pnictide (or chalcogen) materials exhibit a wide range of properties, we believe that S=1 spin and orbital uctuation mediated pairing provides the common thread which is responsible for superconductivity in all of these materials.
February 28, 2011
Jeff Moersch, UTK Earth and Planetary Sciences
"Prospecting for Water with Rovers on Mars"
One of the overarching questions guiding NASA's exploration of the Solar System and elsewhere is "Are we alone?" - in other words, "is life unique to the Earth?" Because liquid water is thought to be one of the basic requirements for life, the central theme for Mars exploration missions over the past decade has been "Follow the Water." This approach has included such diverse activities as mapping the entire planet from orbit using cameras, infrared spectrometers, and gamma ray/neutron detectors, as well as exploring the surface using fixed landers and rovers. This talk will describe efforts undertaken by the Mars Exploration Rovers, Spirit and Opportunity, to characterize the history of ancient water on Mars that is preserved in the geologic record. It will also describe plans to use a neutron detector on the next Mars rover mission, the Mars Science Laboratory, to prospect for present-day subsurface water on Mars.
March 7, 2011
Karol Lang, University of Texas
"Neutrino Physics without Neutrinos:
A Search for Neutrinoless Double Beta Decay"
The observation of neutrino oscillations has proved that neutrinos have mass. This discovery has renewed and strengthened the interest in neutrinoless double beta decay experiments which provide the only practical way to determine whether neutrinos are Majorana or Dirac particles. NEMO-3, located in the Modane Underground Laboratory in the Frejus Tunnel under the French-Italian Alps, is an ongoing experiment looking for neutrinoless double beta decays using a powerful technique for detecting a two-electron final state by employing an apparatus combining tracking, calorimetry, and the time-of-flight measurements. We will present results from NEMO-3 and will discuss the status of SuperNEMO, the next generation experiment that will exploit the same experimental technique to extend the sensitivity of the current search.
March 21, 2011
Eirik Endeve, Oak Ridge National Laboratory
"Simulations of Core-Collapse Supernovae with GenASiS"
Core-collapse supernovae (CCSNe) are the most important source of elements in the Universe. They are multi-messenger events being targeted by observational campaigns covering the entire electromagnetic spectrum, as well as by neutrino and gravitational wave detectors. The interpretation of observations, and our ability to understand the driving mechanism(s) of CCSNe, requires multi-dimensional, multi-physics simulations. We are developing the GenASiS framework to study core-collapse supernova explosions on supercomputers. GenASiS will include magnetohydrodynamics (MHD), gravity, and neutrino radiation transport. The inclusion of magnetic fields (viz. MHD) in simulations may be required to explain the properties of some CCSNe, but also the intense magnetic fields of the collapsed supernova remnants known as pulsars. Resent simulations, performed using the MHD capabilities of GenASiS, illustrate that strong magnetic fields may arise quite generally in the supernova environment. Furthermore, the simulations demonstrate the multi-dimensional and multi-scale nature of CCSNe, as well as the need for massive computational resources. The role of magnetic fields in CCSNe, and future directions towards more realistic simulations will be discussed.
March 28, 2011
Konstantinos Orginos, College of William and Mary
"Lattice Gauge Theory"
Quantum Chromodynamcs (QCD) is now established as the theory of strong interactions. A plethora of hadronic physics phenomena can be explained and described by QCD. From the early days of QCD, it was clear that low energy phenomena require a non-perturbative approach. Lattice QCD is a non-perturbative formulation of QCD that is particularly suited for numerical calculations. However, it was obvious from the very beginning that enormous computer power is required to achieve results relevant to phenomenology. Today, in the era of petaflop computing, a significant stream of reliable results has been produced from Lattice QCD. I will review the most recent results, relevant to Nuclear Physics. In particular, I will focus on results for the spectrum, structure and interactions of hadrons, as well as discuss recent studies of QCD at non-zero temperature. Finally, I will comment on the opportunities opening up as we approach the era of exaflop computing.
April 4, 2011
David Mandrus, UTK Materials Science and Engineering
"The indispensible role of new materials in condensed matter physics"
In this talk I will discuss how progress in condensed matter physics is enabled by the discovery of new materials, and I will also discuss strategies for finding new materials that challenge our physical understanding.
April 11, 2011
Tom Handler, UTK Physics and Astronomy
"Science and Public Policy"
The United States faces many issues that involve science. Issues ranging from climate change to nano-technology, from human genomics to modified food crops. What is the role that science plays in determing what the public policy for these issues should be? How as scientists should we respond to requests for advice?
April 18, 2011
Pedro Marronetti, Florida Atlantic University
"When Black Holes Collide: Interactions between the Simplest Objects in the Universe"
The field of numerical relativity experienced a growth spurt in the past five years that took the two-body problem in general relativity from the category of "really hard problems" to the realm of "things we know how to do". The numerical simulation of binary black holes in circular orbits, the holy grail of numerical relativity, is now a tractable problem that has lead to some of the most interesting results in General Relativity in recent years. I will cover the latest achievements and highlight the field's next challenges with emphasis in the numerical aspects of these simulations.