Colloquium Schedule
UT Physics > About Our Department > Colloquium Schedule
Unless otherwise noted, the physics colloquia begin with refreshments at 3:00 p.m. in Room 307 of the Science and Engineering Research Facility (SERF Building), with the talk following at 3:30 p.m. Colloquium Contact: Dr. Hanno Weitering To see last semester's speaker list, check the Fall 2002 Colloquium Schedule
Spring 2003
| Date | Speaker and Topic |
|---|---|
| January 13 | Mike D. Barnes Chemical Sciences Division, ORNL Title: Oriented semiconducting polymer nanorods: New insights into intramolecular structure of conjugated polymers Contact: Ray Garrett |
| January 20 | No Colloquium (MLK Holiday) |
| January 27 | Prof. Sokrates Pantelides McMinn Professor of Physics, Vanderbilt University Title: It's a small, small world -- but what's really different at the nanoscale? Contact: Hanno Weitering |
| February 3 | Prof. Yuri Kamychkov UT Department of Physics and Astronomy Title: First observation of reactor anti-neutrino flux disappearance in KamLAND |
| February 10 | Dr. Sam Jiang Materials Science Division, Argonne National Laboratory Title: Thin Film Exchange-Spring Magnets Contact: Hanno Weitering and Jian Shen (ORNL) |
| February 17 | Prof. Leonard C. Feldman Stevenson Professor of Physics, Vanderbilt University Title: Semiconductor Physics: The On-Going Revolution Contact: Hanno Weitering |
| February 20: Special Physics Colloquium/Chemical Physics Symposium | Professor Uzi Landman Regents' and Institute Professor, Georgia Tech Title: Small is different: modelling materials in the nanoscale non-scalable regime Contact: Bob Compton |
| February 24 | Dr. Edwin Kolbe Institut für Physik der Universität Basel Title: Nuclei and Supernovae as Laboratories for Fundamental Physics Contact: Yuri Kamyshkov |
| March 3 | Dr. John T. Simpson Advanced Lasers and Optical Technologies, Oak Ridge National Laboratory Title: Research Overview of ORNL's "Advanced Optical, Diagnostic, and Technology" Group Contact: Joe Macek or Ray Garrett |
| March 10 | Jeff Blackmon Physics Division, Oak Ridge National Laboratory Title: Cooking up Elements in Big Explosions |
| March 17 | No Colloquium: Spring Break |
| March 24 | Dr. John Tranquada Group Leader, Neutron Scattering, Brookhaven National Laboratory Title: Competing Interactions, Charge Stripes, and High-Temperature Superconductivity Contact: Pengcheng Dai |
| Special Colloquium: March 26 Please Note: Refreshments will be at 3:00 p.m. in 201 Nielsen Physics Building; Colloquium will be at 3:30 p.m. in Room 304 Nielsen |
Dr. Paul Huffman National Institute of Standards and Technology Title: Measuring the Neutron Lifetime with Magnetically Trapped Neutrons Contact: Carrol Bingham |
| March 31 | Dr. Lawrence S. Cardman Associate Director for the Physics Division, Jefferson Lab Title: Building Nucleons and Nuclei from Quarks and Glue: Early Results from the Research Program at Jefferson Lab Slides from Dr. Cardman's Talk (.pdf) Contact: Witek Nazarewicz |
| April 7 | Professor Dr. Achim Richter Institut fuer Kernphysik Technische Universitaet Darmstadt Title: Playing Billiards with Microwaves - Quantum Manifestations of Classical Chaos Contact: Witek Nazarewicz |
| April 9 | Dr. Robert Grzywacz ORNL and Warsaw Univeristy Title: A New Type of Radioactivity: The Two-Proton Decay of 45Fe Contact: Carrol Bingham |
| Special Physics Colloquium April 10 |
Dr. Mike Norman Group Leader, Condensed Matter Theory Materials Science Division, Argonne National Laboratory Title: TBA Contact: Hanno Weitering |
| April 14 | Dr. Ian S. Anderson Experimental Facilities Division Director of the Spallation Neutron Source, Oak Ridge National Laboratory Title: Why Neutrons? Contact: Geoff Greene |
| April 21 | Dr. David Erickson Director, Climate and Carbon Research Center for Computational Sciences, Oak Ridge National Laboratory Title: Global numerical climate modeling: Why is T getting larger? Contact: Hanno Weitering |
| April 28 | Professor Barry Holstein University of Massachussetts, Amherst Title: Aristotle was Right: Heavier Objects Fall Faster Contact: Geoff Greene or Witek Nazarewicz |
| May 5 | Professor Peter C. Ecklund Penn State University Title: Carbon Nanotubes--A Thermoelectric "Nano-Nose" Contact: Hanno Weitering |
| May 21 | Professor Jainendra Jain Erwin W. Mueller Professor of Physics, Penn State University Winner of the 2002 Buckley Prize Title: The Role of Analogy in Unraveling the Fractional-Quantum-Hall-Effect Mystery Contact: Hanno Weitering |
Abstracts
Mike D. BarnesChemical Sciences Division, ORNL
Oriented semiconducting polymer nanorods: New insights into intramolecular structure of conjugated polymers
Currently there is a great deal of interest in strategies to orient and align conjugated segments of semiconducting polymers both from the standpoint of fundamental optical and polymer physics, as well as from the standpoint of practical polymer-based opto-electronic devices. Furthermore there is intense interest in effects of nanoscale confinement of polymeric systems and how such confinement (on a length scale comparable to the persistence length) affects structural and photophysical properties. Using an ink-jet printing approach to isolate single chains of a conducting polymer, we have observed dramatic alteration of structural, photochemical, and spectroscopic polarization, properties of a common semiconducting polymer under nanoscale confinement. Due in part to the excess charge on the particle/molecule produced during droplet generation, the rod-shaped polymer molecules are uniformly oriented at the coverglass surface with the long axes aligned in the z-direction. We have observed similar orientational behavior for different conjugated polymers, suggesting that this technique is general for a broad class of stiff-chain polymers. These results suggest a number of exciting applications in polymer-based photonics and molecular-scale optoelectronics.
Return to Colloquium Calendar
Prof. Sokrates Pantelides
McMinn Professor of Physics, Vanderbilt University
It's a small, small world -- but what's really different at the nanoscale?
Phycisists and chemists have been doing science at nanoscale dimensions for more than hundred years -- that's the realm of electrons, atoms, molecules.... Yet, nanoscience and nanotechnology is a new frontier that is generating interdisciplinary research funding, start-up companies and promises for new revolutionary technologies. What's new and what's different in all this? After an overview, the talk will describe specific examples from the speaker's research programs that illustrate the unique role of the nanoscale as a new frontier.
Return to Colloquium Calendar
Prof. Yuri Kamychkov
UT Department of Physics and Astronomy
First observation of reactor anti-neutrino flux disappearance in KamLAND
Since the first detection of anti-neutrinos by F.Reines and C.L. Cowan fifty years ago (Nobel prize awarded to F. Reines for detection of the neutrino in 1995) many efforts have been made to measure as well as to predict theoretically the anti-neutrino fluxes from fission reactors. Good agreements at the level of a few percent between calculations and measurements have been established when experiments were performed at small (~1 km or less) distances from the reactors. For the first time in the KamLAND experiment, where average distance between reactor and detector is ~ 180 km, the "disappearance" of anti-neutrino flux was observed. We will discuss the significance of this result in relation to neutrino masses and to the explanation of the long-standing problem of the lack of Solar neutrinos.
Return to Colloquium Calendar
Sam Jiang
Materials Sciences Division, Argonne National Laboratory
Thin Film Exchange-Spring Magnets
Permanent magnets are found in a wide variety of applications ranging from particle accelerators and free electron lasers, to motors and generators in automobiles, to sensors and actuators in miniaturized machines. The exchange-spring magnet, which is based on interfacial exchange coupled soft and hard ferromagnetic nano-phases, exemplifies the materials-by-design approach at the nanometer scale to create the next-generation high performance permanent magnet materials. Using magnetic thin film multilayers as model exchange-spring systems proves to be a promising intellectual path that helps generate the mechanistic and materials insights needed to lead to the eventual realization of permanent magnet materials with potential commercial impact. I will describe our research on coupled hard/soft magnetic multilayers as model exchange-spring systems, with an emphasis on uncovering the fundamental magnetic reversal processes and the correlation between microstructure and magnetic properties. The goal is to illustrate the rich opportunities to understand and hopefully improve permanent magnets by utilizing the principles of nanotechnology and the microscopic tools of modern materials science.
Return to Colloquium Calendar
Prof. Leonard C. Feldman
Stevenson Professor of Physics, Vanderbilt University
Semiconductor Physics: The On-Going Revolution
The "silicon culture" is the critical advance of the last century. Innovation in condensed matter/materials physics has been the driving force for this semiconductor revolution. Future progress will depend on new physics, new materials and materials combinations. This talk will review the physics challenges, limits and opportunities inherent in these new directions. Specific examples arise from the growth of bio-chips, the need to combine optics with electronics (the III-V/IV problem), nanofluidics, organic electronics, spin systems and nano-scale materials. Issues limited by materials physics will be emphasized.
Return to Colloquium Calendar
Professor Uzi Landman
Regents' and Institute Professor, Georgia Tech
Small is different: modelling materials in the nanoscale non-scalable regime
Investigations of finite aggregates of small sizes and reduced dimensionalities open avenues for systematic explorations of the physical factors and unifying principles that underlie the transition from the atomic and molecular domain to the condensed phase regime. Such behavior, where the dependence of the behavior of the system on it's size is non-scalable with the physical size of the system, but rather where Small is Different in an essential way, is emergent in nature; that is, the exhibited behavior is characteristic of the assembly of particles rather then being a property of the individual constituents, showing behavior on a larger scale then that characterizing the (relatively local) interactions between the elementary components of the system. Identification and understanding of the microscopic origins of such emergent phenomena, are of fundamental importance for elucidation of the principles of self-assembly and self-selection operative at the nano-scale, as well as of great potential relevance to technological developments at the dawn of the new millennium. These physical and methodological issues will be discussed and illustrated using results obtained through large-scale classical and quantum simulations. Topics will include: (i) Formation mechanisms, mechanical, quantized electric conductance, and chemical properties of metal and semiconductor nanowires and their interconnections [1]; (ii) Atomic-scale friction, control of friction through modifications of molecular architecture, and nanotribological processes in lubricated junctions [2]; (iii) Generation, stability and breakup of nanojets [3a] and deposited fractal islands [3b]; (iv) Nanocatalysis by small gold and palladium clusters [4], and guidelines for atomic-scale control of catalytic activity; (v) Spontaneous symmetry breaking leading to formation of crystallized clusters (Wigner electron molecules) in individual two-dimensional quantum dots, and quantum-dot-molecules [5], (vi) Emergence of magnetism in free and surface-supported small palladium clusters [6], and (vii) Charge transport in DNA [7].
1. U. Landman et al, Microscopic Mechanisms and Dynamics of Adhesion, Microindentation and Fracture, Science 248, 454 (1990); U. Landman et al., Metal-Semiconductor Nanocontacts: Silicon Nanowires, Phys. Rev. Lett. 85, 1958 (2000).
2. B. Bhushan, J.N. Israelachvili and U. Landman, Nanotribology: Friction, Wear and Lubrication at the Atomic Scale, Nature 374, 607 (1995); J. Gao, W.D. Luedtke, and U. Landman, Friction Control in Thin-Film Lubrication, J. Phys. Chem. Chem. B 102, 5033 (1998); J. Gao et. al., Tribol. Lett. 9, 3 (2000).
3. (a) M. Moseler and U. Landman, Formation, Stability and Breakup of Nanojets, Science 289, 1165 (2000). (b) C. Brechignac et al., Phys. Rev. Lett., 88, 196103 (2002).
4. A. Sanchez et al., When Gold is not Noble: Nanoscale Gold Catalysts, J. Phys. Chem. A 103, 9573 (1999); S. Abbet, U. Heiz, H. Hakkinen, and U. Landman, CO Oxdidation on a Single Pd Atom Model Catalyst, Phys. Rev. Lett, 86, 5950 (2001); M. Moseler, H. Hakkinen, U.Landman, 89, 033401-1, (2002); H. Hakkinen et. al., Angew. Chem. (2003).
5. C. Yannouleas and U. Landman, Spontaneous Symmetry Breaking in Quantum Dots and Dot-Molecules, Phys. Rev. Lett. 82, 5325 (1999); ibid., Collective and Independent-Particle Motion in Two-Electron Artificial Atoms, Phys. Rev. Lett. 85, 1726 (2000); Coupling and Dissociation in Artificial Molecules, Euor.. Phys. J D 16, 373 (2001).
6. M. Moseler, H. Hakkinen, R.N. Barnett, and U. Landman, Structural and Spin Isomers of Neutral and Anionic Palladium clusters, Phys. Rev. Lett. 86, 2545 (2001); 89, 176103 (2002).
7. R.N. Barnett, C.L. Cleveland, A. Joy, U. Landman, and G.B. Schuster, Charge Migration in DNA: Ion-Gated Transport, Science 294, 567 (2001).
Return to Colloquium Calendar
Dr. Edwin Kolbe
Institut für Physik der Universität Basel (Switzerland)
Nuclei and Supernovae as Laboratories for Fundamental Physics
Last year's (half) Nobel Prize to Raymond Davis and Masatoshi Koshiba has underlined the importance of detecting neutrinos from cosmic sources. One can expect that a detailed study of supernova neutrinos (distinguishing their flavors and energy spectra) would produce results of similar value. Based on continuum RPA calculations I will demonstrate by a few examples the important role that neutrino induced reactions on nuclei play for this purpose. I will also show that, by studying nuclear decay modes, one can explore the strangeness content of the nucleon and search for baryon instability. Thus nuclei are laboratories for fundamental physics.
Return to Colloquium Calendar
Dr. John T. Simpson
Advanced Lasers and Optical Technologies, Oak Ridge National Laboratory
Research Overview of ORNL's "Advanced Optical, Diagnostic, and Technology" Group
This presentation will present an overview of various optical research projects being conducted at Oak Ridge National Lab. After the overview, we will present additional details from two of these optical research projects (Subwavelength and photonic bandgap optical devices; Long Wave IR data communications).
Return to Colloquium Calendar
Jeff Blackmon
Physics Division, Oak Ridge National Laboratory
Cooking up Elements in Big Explosions
Novae and supernovae are some of the biggest explosions in the universe. Nuclear reactions occuring in such phenomena were responsible for producing many of the elements that make up our world. Exotic nuclei not normally found on earth can play an important role in these events due to the extreme conditions that occur in the explosion. Beams of short-lived ions have recently been developed at ORNL and other laboratories that allow us to study for the first time some of the processes that are important for the synthesis of elements in these explosions. I will describe the Holifield Radioactive Ion Beam Facility at ORNL and some recent projects there that are helping us better understand novae and supernovae. I will also present a brief preview of future projects, including plans for a next-generation facility, the Rare Isotope Accelerator.
Return to Colloquium Calendar
Dr. John Tranquada
Group Leader, Neutron Scattering, Brookhaven National Laboratory
Competing Interactions, Charge Stripes, and High-Temperature Superconductivity
The occurrence of high-temperature superconductivity in layered copper-oxide compounds has confounded researchers for sixteen years. These materials are doped Mott insulators, and, surprisingly, they retain some features typical of a correlated insulator, such as local antiferromagnetism, even in the superconducting regime. Numerous experiments provide evidence that the contrary insulating and metallic characteristics of the cuprates are accommodated by a spatial separation of the charge carriers and the local magnetic moments that takes the form of a dynamic stripe phase. The experimental evidence for charge stripes will be explained, theoretical rationalizations will be presented, and the implications of stripe correlations for the superconductivity will be discussed.
Return to Colloquium Calendar
Dr. Paul Huffman
National Institute of Standards and Technology
Measuring the Neutron Lifetime with Magnetically Trapped Atoms
Recent success in magnetic confinement of ultracold neutrons (UCN) in an Ioffe-type superconducting magnetic trap should lead to an improved measurement of the neutron lifetime. The trap is loaded through inelastic scattering of 0.89 nm neutrons with phonons in superfluid 4He. Trapped neutrons are detected when they beta decay; energetic decay electrons ionize helium atoms in the superfluid resulting in efficient conversion of electron kinetic energy into light (scintillation). The advantages of this technique over previous experiments are continuous detection of scintillations from decay electrons and the elimination of wall losses and betatron oscillations. Analysis indicates that systematic errors due to neutron losses should be controllable to 10^-5 times the neutron lifetime. We have upgraded our apparatus in preparation for a lifetime measurement by constructing a larger, deeper magnetic trap and have implemented techniques to substantially reduce backgrounds. We are in the process of taking lifetime data with this new apparatus on the at the NIST Center for Neutron Research. Preliminary data will be presented as well as well as future prospects for this experiment at the SNS.
Return to Colloquium Calendar
Dr. Lawrence S. Cardman
Associate Director for the Physics Division, Jefferson Lab
Building Nucleons and Nuclei from Quarks and Glue: Early Results from the Research Program at Jefferson Lab
The Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab is a unique new tool for the study of atomic nuclei that can provide intense, cw beams of polarized electrons with energies of up to 5.7 GeV. The accelerator began delivering beam for physics research in October 1995, and has been in full operation since December 1998.
CEBAF supports a broad range of nuclear physics research aimed at addressing key questions in the field, such as: how nucleons are constructed from the quarks and gluons of QCD; how the strong force arises from the underlying QCD quark-quark interaction; and where the conventional description of nuclei based on nucleons interacting via the nuclear force breaks down. The broad outlines of this research program will be reviewed, and examples of the exciting results from the first round of experiments will be presented.
Return to Colloquium Calendar
Professor Dr. Achim Richter
Institut fuer Kernphysik, Technische Universitaet Darmstadt
Playing Billiards with Microwaves - Quantum Manifestations of Classical Chaos
Flat microwave resonators shaped in the form of billiards are particularly well suited to study the quantum mechanical behavior of classically chaotic systems because of the formal equivalence of the respective wave equations, i.e. the Helmholtz and the Schroedinger equation. With superconducting resonators of high quality factors it is possible to measure the spectrum of eigenmodes and their eigenfunctions completely and to determine their statistical properties. Two- and three-dimensional billiards systems of different chaoticity are discussed and it is shown that they display generic features which are also evident in real physical systems like atoms, molecules and nuclei.
Return to Colloquium Calendar
Dr. Robert Grzywacz
ORNL and Warsaw University
A New Type of Radioactivity: The Two-Proton Decay of 45Fe
Two-proton radioactivity was first postulated in 1960 by V.I. Goldansky[1]. This decay mode is characterized by the simultaneous emission of two protons from the ground state of the nucleus. It can occur in only a few nuclei which have an excess of protons. Such nuclei are extremely difficult to synthesize and study experimentally, such that it has only recently become possible to perform such en experiment.
In two pioneering experiments [2,3] performed at heavy ion accelerator laboratories GSI and GANIL, the first evidence has been found for two-proton radioactivity in the decay of the nucleus 45Fe. Beams of 58Ni nuclei accelerated to relativistic energies were used to produce the 45Fe ions in fragmentation reactions. Magnetic spectrometers were used to select them from the other more abundant reactions products. A sophisticated detection system using a new type of electronics based on Digital Signal Processing was implemented. This novel technique proved to be an essential element in making the discovery.
The conditions for the double-proton emission process, an explanation of the experiments and perspectives for future studies will be presented. [1] V. I. Goldansky, Nucl. Phys. 19 (1960) 482 [2] M. Pf\"utzner et al., Eur. Phys. J. A 14 (2002) 279 [3] J. Giovinazzo et al., Phys. Rev. Lett. 89 (2002) 102501
Return to Colloquium Calendar
Dr. Mike Norman
Materials Science Division, Argonne National Laboratory
The Nature of High Temperature Cuprate Superconductors
I review the field of high temperature cuprate superconductors, with an emphasis on the nature of their electronic properties. After a general overview, I concentrate on recent results obtained by photoemission, neutron scattering, optics, and tunneling. I conclude by reviewing efforts which attempt to identify the energy savings involved in the formation of the superconducting ground state.
Return to Colloquium Calendar
Dr. Ian Anderson
Experimental Facilities Division Director of the Spallation Neutron Source, Oak Ridge National Laboratory
Why Neutrons?
Much of what underpins our present-day quality of life depends upon our understanding, and consequent control, of the behavior of materials. Ultimately, this behavior is dictated by their structure and dynamics at the atomic and mesoscopic level and our knowledge of these comes from a wide range of sophisticated techniques. The most important of these techniques are based on scattering from matter. The neutron is, in many ways, the ideal probe for the investigation of condensed matter, having significant advantages over other forms of radiation in the study of microscopic structures and dynamics. The Spallation Neutron Source, under construction at Oak Ridge, will provide the US scientific community with the world's most intense neutron beams for basic and applied research in the fields of materials science, magnetic materials, polymers and complex fluids, chemistry and the life sciences. The SNS will provide new tools that will deepen our understanding of the material world.
Return to Colloquium Calendar
Dr. David Erickson
Director, Climate and Carbon Research
Center for Computational Sciences, Oak Ridge National Laboratory
Global numerical climate modeling: Why is T getting larger?
The numerical simulation of the global climate system is a requirement for sound environmental policy and regulation over the next century. The geophysical fluid dynamics of radiatively intense rotating Earth atmospheres, that have molecules and particles embedded in the turbulent flow, are studied using detailed numerical models. The climate impact of increasing atmospheric CO2, as well as other trace species, is simulated at 2o x 2o latitude/longitude resolution at 28 vertical levels every 15 minutes for centuries. The present and future computational requirements at ORNL for this type of geophysical simulation are discussed within the context of future climate prediction and an assessment of associated uncertainties.
Return to Colloquium Calendar
Professor Barry Holstein
University of Massachusetts, Amherst
Aristotle was Right: Heavier Objects Fall Faster
The concept that all objects fall at the same rate is one which was supposedly tested by Galileo at the Leaning Tower of Pisa and which we all try to teach our students in introductory physics. Nevertheless recent calculations raise questions about the validity of this idea when finite temperature is taken into account and the physics associated with these modifications will be discussed.
Return to Colloquium Calendar
Professor Peter C. Ecklund
Penn State University
Carbon Nanotubes-A Thermoelectric Nano-nose
We present results of extensive investigations of the interaction of gases and molecular vapors with carbon nanotubes. The experiments were carried out on thin films of purified bundles of carbon nanotubes and include four-probe resistance, thermoelectric power and Raman scattering measurements. We find that the transport properties are most sensitive to gases that chemisorb and undergo weak charge transfer reactions. It is perhaps surprising that these transport parameters are even sensitive to physisorbed molecular gases, for example, six-membered ring molecules with the strength of the effect correlating with the number of pi electrons on the molecule. Furthermore, even contact with gases such as He and N2, where the collisions must be driving the perturbation on the transport properties, can be detected. Finally, we present our data on the effects of the contact of molecular oxygen (below 200C) with carbon nanotubes and attempt to reconcile what we see as a charge transfer phenomenon with experimental and theoretical results of other groups.
Return to Colloquium Calendar
Professor Jainendra Jain
Erwin W. Mueller Professor of Physics, Penn State University
Winner of the 2002 Buckley Prize
The role of analogy in unraveling the fractional-quantum-Hall-effect mystery
When all else fails, the method of analogy is the most powerful weapon in a theoretical physicist's arsenal. I will talk about how the analogy to a well understood problem gave us the key insight into the rich, non-perturbative physics of the fractional quantum Hall effect, and in the process led to the discovery of a new kind of fermionic particles called "composite fermions."
Return to Colloquium Calendar
This page was last updated on May 15, 2003.
Please send comments to cal@utk.edu.