Colloquia - Spring 2010
January 26, 2010
3:00 pm (Tuesday)
Dr. Hani Elsayed-Ali
Old Dominion University
Pulsed Laser Deposition Studies at the Applied Research Center
Pulsed laser deposition (PLD) is used to grow semiconductor thin films and quantum dots. A review of the nucleation and growth studies using in-situ reflection high energy electron diffraction (RHEED), atomic force microscopy (AFM), and scanning tunneling microscopy (STM) will be given. Recent results on electronically induced epitaxy will be presented. As an example of a device grown by PLD, fabrication and testing of a mid infra red Si/Ge quantum dot detector will be described.
February 11, 2010 3:00 pm (Thursday)
Dr. Nicola Scafetta
Duke University
Celestial origins of the climate oscillations, a review
The climate of the Earth has always changed. Herein I will focus on those mechanisms that link climate changes to astronomical phenomena. I will discuss: 1) how changing galactic environment of the solar system as it crosses the spiral arms of the Milky Way may explain the warm and ice periods of the Phanerozoic during the last 600 million years; 2) how the Milankovic's variations in eccentricity, axial tilt, and precession of the Earth's orbit resulted in about 100,000-year ice age cycles during the Quaternary glaciation over the last few million years; 3) how solar variation (plus volcano eruptions) have contributed to the pre-industrial climate change from 1000 to 1900; 4) how solar and orbital changes (plus volcano eruptions and anthropogenic emission) have contributed to climate change during the last century. Although the anthropogenic emissions have contributed to the global warming observed during the last century, I will show that the Anthropogenic Global Warming Theory (AGWT), which claims that more than 90% of the observed warming since 1900 and practically 100% of the observed warming since 1970 is man-induced, must be severely revised. I will present empirical evidences that the last century was characterized by large natural climate oscillations that can be correlated to extraterrestrial solar or planetary oscillations such as a large 60 year cycle. The presence of these natural cycles would imply that climate can cool in the next decades.
February 16, 2010 3:00 pm (Tuesday)
Dr. John Weiner
NIST
Extraordinary optical transmission revisited: how light gets through isolated or periodic arrays of subwavelength slits and holes (or not)
Pulsed laser deposition (PLD) is used to grow semiconductor thin films and quantum dots. A review of the nucleation and growth studies using in-situ reflection high energy electron diffraction (RHEED), atomic force microscopy (AFM), and scanning tunneling microscopy (STM) will be given. Recent results on electronically induced epitaxy will be presented. As an example of a device grown by PLD, fabrication and testing of a mid infra red Si/Ge quantum dot detector will be described.
February 23, 2010 3:00 pm (Tuesday)
Dr. Declan De Paor
Old Dominion University
Extraordinary optical transmission revisited: how light gets through isolated or periodic arrays of subwavelength slits and holes (or not)
Earth and space sciences have long shared a common methodology based on maps and map-making. Both sciences began with mapping and both continue to rely on maps as the databases on which novel observations are made, models are constructed, and hypotheses are tested. In the case of astronomy, mapping the celestial sphere allowed the ancients to plot paths of planets, leading eventually to Heliocentrism, and to this day maps are used to discover comets, explore planets and moons, and study the cosmos on ever-larger scales, from the Hubble Deep Field to the WMAP. From the earliest of the geological and geophysical surveys, combinations of maps and cross sections aided visualization and analysis of tectonic structures. On the other hand, traditional maps have always been at least partially works of art. They are difficult to assess or validate, and they can anchor the viewer’s perception in a current style of interpretation. In order to make tectonic maps more quantitative and falsifiable, I have developed methods of displacement, strain, and kinematic analysis and have applied these methods in a range of settings. With the recent emergence of new mapping technologies, including digital field devices and virtual globes, my students, colleagues, and I are building innovative 4-D visualizations that zoom from outcrop to planetary scale while moving forward and backward in time, and we are assessing their effectiveness both as learning resources and research tools. In the future, we aim to coordinate spherical and full-dome digital projections to create a cognitive link between the planetary and celestial domains
March 16, 2010 3:00 pm (Tuesday)
Dr. Timothy Chupp
University of Michigan
Fundamental Symmetry Studies with Rare Atoms
The Standard Model of elementary particle interactions explains almost everything that has been measured or observed, yet it appears to be incomplete - a low-energy manifestation of a more general model. New physics is sought at the highest energies, where new particles may be discovered, and by making precision measurements that make use of symmetry violations to reveal new interactions. Rare atoms are unstable species having Z=0 to 92 that are produced in significant quantities at a number of facilities world-wide, and several special cases provide enhanced sensitivity to violations of parity and time-reversal invariance when polarization is used as a variable. In this talk, I will describe motivations and experiments with neutrons and with rare atoms designed to probe the Standard Model and beyond.
March 23, 2010 3:00 pm (Tuesday)
Dr. Bill Barletta
MIT
Steps toward the Attosecond Frontier of X-ray Science
The combination of optical manipulation of beams (OMB) and the free electron laser process offer the means to exploit rapid developments in quantum optics to enable the study of dynamical processes on timescales
March 25, 2010 3:00 pm (Tuesday)
Dr. Alex Gurevich
Florida State University
New Superconducting Materials for the Next Generation Particle Accelerators.
Achieving accelerating field gradients above 50 Mv/m in superconducting cavities for particle accelerators will require novel cavity designs and materials other than Nb given that the SRF performance of the best Nb cavities has approached the limits set by the physics of the superconducting Meissner state under strong rf fields. In this talk I will give an overview of the fundamental physics and materials science issues which determine these SRF limits, and discuss possible ways of increasing the cavity performance well beyond the intrinsic limits of Nb technology. One possibility based on the multilayer coating of Nb cavities is already being pursued by several groups worldwide. This approach opens up the opportunity of increasing the accelerating field gradients and reducing the operating costs by taking advantage of many existing materials with superconducting characteristics much better than those of Nb.
March 30, 2010 3:00 pm (Tuesday)
Dr. Wick Haxton
Berkeley
Solar Neutrinos and Planetary Formation
Pulsed laser deposition (PLD) is used to grow semiconductor thin films and quantum dots. A review of the nucleation and growth studies using in-situ reflection high energy electron diffraction (RHEED), atomic force microscopy (AFM), and scanning tunneling microscopy (STM) will be given. Recent results on electronically induced epitaxy will be presented. As an example of a device grown by PLD, fabrication and testing of a mid infra red Si/Ge quantum dot detector will be described.
April 13, 2010 3:00 pm (Tuesday)
Dr. Michael Schulz
Missouri University of Science and Technology
Three-Body Dynamics of Fragmentation Processes in Simple Atomic Systems
Understanding Nature requires addressing two major topics: first, we have to understand the forces acting in Nature. It is well established that the fundamental forces are mediated by the exchange of a gauge boson, which means that this mediation is fundamentally a two-body process. This property directly leads to the second topic which must be addressed: the spatial and temporal development of systems containing more than two particles under the influence of these pairwise acting forces. It is well established that the Schrödinger equation is not analytically solvable for such systems even when the underlying forces are completely understood. This is known as the few-body problem (FBP). For two reasons atomic fragmentation processes are particularly suitable to study the FBP: a) the underlying force in atomic systems is essentially understood. b) For simple atomic systems the particle number is small enough to make kinematically complete experiments measuring the properties of each particle feasible. In this talk recent experiments on the most fundamental few-body system (p + H) will be presented. A thorough theoretical analysis of the experimental data led to a major advancement of our understanding of the fragmentation dynamics.
April 27, 2010 3:00 pm (Tuesday)
Old Dominion University
Senior Thesis Presentations
James Haus
"Automation and Testing of a Drift Chamber Wire Tensionometer"
Joshua Elliott
"Voltage Dependence of Particle Efficiency for the Prototype CLAS12 Drift Chamber"
Ermal Rrapaj
"Evolution of Generalized Parton Distributions in Quantum Chromodynamics"