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Spring 2008

Schedule Spring 2008

January 15, 2008
3:00 pm (Tuesday)

Dr. Rolland Johnson
Muons, Inc.

Bright Muon Beams for Colliders, Neutrino Factories, and Muon Physics

New inventions are rapidly improving the prospects for high luminosity muon colliders for Higgs factories and at the energy frontier. Recent analytical calculations, numerical simulations, and experimental measurements are coming together to make a strong case for a series of machines to be built, where each one is a precursor to the next, with its own unique experimental and accelerator physics programs. A strategy will be outlined for achieving an almost unlimited program of experimental physics based on the cooling and acceleration of muon beams. The inventions, calculations, and experiments that are promising bright beams for muon accelerators and storage rings will be discussed as potential Ph. D. thesis topics.

January 29, 2008
3:00 pm (Tuesday)

Dr. Scott Schiff
Clemson University


Educational research indicates that students should collaborate on interesting tasks and be deeply involved with the material they are studying. We promote active learning in a redesigned classroom of 100 students or more. We believe the SCALE-UP Project has the potential to radically change the way large classes are taught at colleges and universities. The social interactions between students and their teachers appear to be the "active ingredient" that makes the approach work.

Classtime is spent primarily on "tangibles" and "ponderables ". These are handson activities, simulations, or interesting questions and problems. There are also some hypothesis-driven labs where students have to write detailed reports. Students sit in three groups of three students at 6 or 7 foot diameter round tables. Instructors circulate and work with teams and individuals, engaging them in Socratic-like dialogues. The setting is very much like a banquet hall, with lively interactions nearly all the time. Many colleges and universities are adopting/adapting the SCALE-UP room design and pedagogy. Engineering schools are especially pleased with the course objectives, which fit in well with the requirements for ABET accreditation.

* Ability to solve problems is improved
* Conceptual understanding is increased
* Attitudes are improved
* Failure rates are drastically reduced, especially for women and minorities
* "At risk" students do better in later engineering statics classes

The colloquium will give a general overview of SCALE-UP. The workshop will focus on how to implement SCALE-UP in different disciplines using specific pedagogical examples.

February 21, 2008
12:20 pm (Thursday)

Note unusual date and time

Dr. Sumanta Tewari
University of Maryland

Unconventional Magnetism : Ginzburg-Landau Theory of Non-Collinear Magnetic Ordering in Multiferroics

Multiferroics are materials that display an amazing coexistence and interplay of long range ferromagnetic and ferroelectric orders. The magnetization (electric polarization) of these materials can be altered by
applying an external electric (magnetic) field, such cross-correlations leading to intense interest in the possibility of novel magnetoelectric devices. It was observed recently that the multiferroics that show the strongest cross-correlations are non-collinear spiral magnets. With hints
from the theories of some liquid crystals, which bear a family resemblance to these systems, I shall develop a Ginzburg-Landau description of this new class of materials. The resulting theory will allow us to explain as well as predict many unusual and outstanding experimental observations.

February 28, 2008
12:20 pm (Thursday)

Note unusual date and time

Dr. Andrey Shitov
Brookhaven National Laboratory

Relativity in a Pencil Trace: Atomic Collapse in Graphene

Electrons in graphene, a novel two-dimensional material, behave similarly to Dirac particles. Quantum relativistic effects defying common intuition are manifested in unusual transport properties of this system. In this talk, I will explore the connection between the problem of charged impurity in graphene and the physics of superheavy atoms. I will explain how graphene opens a way to investigate in the laboratory the phenomenon of Dirac vacuum reconstruction in strong fields, long sought for but inaccessible in high-energy experiments.

March 4, 2008
12:20 pm (Tuesday)

Note unusual time

Dr. Igor Beloborodov
James Franck Institute, University of Chicago

Artificial Nanosolids

Artificial nanosolids, arrays of nanoscale grains interacting with each other through electron tunneling, offer rich new horizons of novel macroscopic behavior emerging from nanoscale structure and dynamics. Fundamental microscopic phenomena such as Coulomb correlation, disorder and coherence produce dramatically new and programmable bulk behavior when mediated by nanoscale granular structure. Each building block of these new materials can be viewed as a tiny cluster of atoms of metallic, semiconducting or superconducting elements. These clusters are not as small as molecules but not as large as macroscopic objects. I will review our progress made in the last several years in understanding the properties of artificial nanosolids. In particular, I will discuss the following topics:

1) Introduction to physics of artificial nanosolids
2) Novel transport regimes
3) The phase diagram of artificial nanosolids
4) Future opportunities

I. Beloborodov et al., Reviews of Modern Physics, 79, 469 (2007).

March 4, 2008
3:00 pm (Tuesday)

Dr. Lawrence M Krauss
Case Western Reserve University

Our Miserable Future

In a universe dominated by a cosmological constant things are as bad as they can possibly be. During this lecture I will discuss the future of life, of computation and information processing, of galaxies and large scale structure, and the future of cosmology. While generally miserable, the news is not all bad: Even if protons ultimately decay, diamonds will be forever, or at least will last as long as our universe does.

March 18, 2008
12:20 pm (Tuesday)

Note unusual time

Dr. Charles Reichhardt
Theory Division, Los Alamos National Laboratory

Colloids: a Model System to Explore Complex Matter with Competing Interactions

There are a wide variety of applications for colloidal particle assemblies including the creation of synthetic photonic band gap materials, sensor arrays, and self-assembled templates for the mass fabrication of nanostructures. In addition to these practical applications, colloids are also ideal for studying the complex behavior arising in systems with competing interactions. I will show that such competing interactions can give rise to novel self-organized stripe, labyrinth, and network structures which may be relevant to charge ordering in cuprates and manganites. I will also demonstrate that colloids can be used to create artificial nuclei systems, including a colloidal version of the so-called pasta phases that may exist in dense nuclear matter. When the colloids are exposed to a periodic optical trap array, numerous statistical mechanics models can be readily created including Ising, Potts, and artificial spin ice systems, as well as new phases.

March 18, 2008
3:00 pm (Tuesday)

Dr. Mikhail N Shneider
Princeton University

Neutral Molecular Ensembles In Optical Lattices

In this talk, our recent theoretical and experimental results on the interaction of optical lattices with neutral gases will be reviewed. A periodic optical dipole potential is created by the interaction between a polarizable particle and the field of an optical interference pattern (optical lattice) created by counter propagating laser fields. Small gas density perturbations produced by the relatively weak intensity laser beams (when the optical potential well depth << kT) can be used for powerful nonintrusive diagnostics based on Coherent Rayleigh-Brillouin scattering in gases. A bulk drift can be induced in a gas by the traveling optical lattice, even when the mean kinetic energy is much greater that the maximum dipole potential of the optical field. In this process the transfer of energy from the optical lattice to the gas is analogous to Landau damping of a plasma wave by charged particles. With increasing laser beam intensities, the optical lattice potential depth increases and a large quantity of gas particles can be trapped. Analysis of the trapped and untrapped motion of particles demonstrates that atoms and molecules can be accelerated from room temperature to velocities in the 10 to 100 km/s range over distances of 100s of microns. Also, we suggested a deceleration scheme using nondissipative optical forces to slow the molecules by decelerating the optical lattice from an initial velocity equal to that of the supersonic gas. Recently, such experiment was successfully performed by Dr. Peter Barker s group in Great Britain. Also, we describe the coupling of non-resonant laser radiation to a gas via absorption of energy and momentum from an optical lattice. These processes in the collisional gas regime result in the formation of gas jets in free space and bulk drift in a capillary and can be used for microscale multicomponent gas mixing or separation.

March 20, 2008
12:20 pm (Thursday)

Note unusual date and time

Dr. Cynthia Reichhardt
Theory Division, Los Alamos National Laboratory

Local Probes at the nanoscale: Avalanches, melting, and jamming transitions

The equilibrium and nonequilibrium dynamics of a nanoscale medium can be readily accessed by driving a single particle through the system. This type of local probe couples directly to the size and energy scales of heterogeneities in the material, permitting the observation and control of rare events which may trigger intermittent or avalanche-like processes. I will describe how magnetic force microscopy can be used to manipulate individual magnetic vortices in a superconductor, and show through simulations that this local probe can be used to study vortex melting, entanglement, and avalanches. I demonstrate that local probes can also be applied to soft and biological matter, including studies of the jamming transition in granular media.

March 27, 2008
12:20 pm (Thursday)

Note unusual date and time

Dr. Mark Jarrell
University of Cincinnati

Massively Parallel Simulations of the Cuprate High Temperature Superconductors

The cuprate high-temperature superconductors hold great technological promise. Non-perturbative, massively parallel simulations have played an essential role in developing an understanding of these materials, from establishing the validity of the most basic cuprate models, to the inclusion of realistic effects such as phonons. New efforts focus on the inclusion first principles band structure, and the role of disorder. A fuller understanding of these realistic effects may lead to the development of better superconducting materials. However, in the years since the discovery of the cuprates, the focus has shifted towards materials with more complex phase diagrams and competing ground states, and correlated multilayers which hold the promise of new functionality. Computational issues, such as the infamous minus-sign problem, preclude the use of conventional methods to study these systems, and are leading to the development of multi-scale many-body formalisms, algorithms and codes, which will be an essential part of the future of computational many-body materials physics.

April 1, 2008
3:00 pm (Tuesday)

Dr. Siegfried Glenzer
Lawrence Livermore National Laboratory

X-ray Thomson scattering in shock-compressed matter

Accurate measurement techniques of the physical properties of dense plasmas have been developed for applications in high-energy density science. This class of experiments produces short-lived hot dense states of matter with electron densities in the range of solid density and higher where powerful penetrating x-ray sources have become available for probing. Experiments have employed laser-based x-ray sources that provide sufficient photon numbers in narrow bandwidth spectral lines allowing spectrally-resolved x-ray scattering measurements from these plasmas. The back-scattering spectrum accesses the non-collective Compton scattering regime, which provides accurate diagnostic information on the temperature, density and ionization states. The forward scattering spectrum has been shown to measure the collective plasmon oscillations. Besides extracting the standard plasma parameters, density and temperature, forward scattering yields new observables such as a direct measure of collisions, quantum effects and detailed balance. In this presentation, we will show new scattering measurements with K-alpha x rays that probe conditions with 10 ps temporal resolution in coalescing shocks.

April 8, 2008
3:00 pm (Tuesday)

Dr. Shannon Cowell

Electroweak interactions - from nuclei to neutron stars

Electroweak interactions play a fundamental role in our understanding of systems ranging from subatomic to astrophysical. Our present understanding of neutrino properties, nuclear structure as well as the evolution of supernovae and neutron stars relies upon an accurate picture of electroweak interactions with nucleons and nuclei. This talk will focus on the role of electroweak interactions in nature, focusing on neutrinos, highlighting the current successes and limitations of modern theory.

April 15, 2008
12:20 pm (Tuesday)

Note unusual time

Dr. Dave Dooling
National Solar Observatory

Building the World's Largest Optical Solar Telescope

A century after George Ellery Hale discovered that magnetism was at the heart of sunspots, the solar physics community is preparing to build the 4-meter Advanced Technology Solar Telescope (ATST) to dissect the origins and mechanisms of solar magnetic activity. Until recently, such a large solar telescope would have been impractical because of Earth's atmosphere. Recent advances in adaptive optics now make it possible to build a solar telescope with spatial resolutions down to 0."022, enabling precise measurements of solar magnetic fields at their fundamental scales. In addition, ATST will have a clear, off-axis optical path allowing coronal as well as on-disk observations, and access to the spectrum from near ultraviolet to deep-infrared. First light is planned for 2016 when the telescope is completed at Haleakala, Maui, Hawaii. Discoveries with ATST will lead to a better understanding of solar activity, including its effects on space weather.

April 15, 2008
3:00 pm (Tuesday)

Dr. Eric Akkerman
Yale University

Photon localization and Dicke superradiance : a cross-over to small world networks

We study photon localization in a gas of cold atoms, using a Dicke Hamiltonian that accounts for photon mediated atomic dipolar interactions. The photon escape rates are obtained from a new class of random matrices. A scaling behavior is observed for photons escape rates as a function of disorder and system size. Photon localization is described using statistical properties of random networks which display a "small world" cross-over. Those results are compared to the Anderson photon localization transition.

April 22, 2008
3:00 pm (Tuesday)

Dr. Alexei Trifonov
Harvard University

Towards Long-Distance Quantum Communication

In my talk I will discuss the current situation with the progress in long-distance quantum communication. Reaching the distance of several hundreds or even thousands of kilometers is the ultimate goal for secure quantum communication, such as quantum key distribution and quantum cryptography as well as for the quantum computation in general. I will start with highlighting the basic ideas in quantum cryptography, current state-of-the-art of device performance and crucial components necessary for successful implementation of long-distance quantum communication. In the next part of the talk possible scenarios and protocols that potentially allow overcoming the current distance limitation and reaching the desired distance span will be analyzed.

April 24, 2008
12:20 pm (Thursday)

Note unusual date and time

Dr. Declan De Paor
Worcester Polytechnic Institute

Recent Developments in Planetary and Lunar Sciences: Implications for Curriculum Development

Research in the natural sciences may involve a combination of discovery, mapping, and modeling, and a breakthrough in one of these approaches can lead to major advances in the field. In the planetary and lunar sciences, revolutionary developments have occurred on all three fronts in the last decade. The rate of discovery of exoplanets, including super-earths, has increased dramatically; mapping of our solar system has benefitted from new data emanating from several NASA and ESA missions, including landings on Mars and Titan; and planetary modeling has been aided by the development of virtual globe and digital astronomy technologies.

These rapid advances present a challenge to the planetary science professor - namely, how to accommodate the stream of new data and theory in a course of fixed duration without abandoning what is most valuable in classical observations and models going back to the ancient Greeks. The author has experimented with real-time, in-class study of NASA and ESA mission data, generation of earth science visualizations using virtual globes, performance science, individual and group research projects, and involvement of undergraduates in the generation of course content. Results suggest that planetary science can serve as a funnel attracting non-traditional students into physical science career paths and that students benefit most from projects that allow them to investigate new worlds actively using new technologies.

April 29, 2008
3:00 pm (Tuesday)

Old Dominion University

Senior Thesis Presentations

Kaon identification in CLAS g11 Photoproduction Data on a Hydrogen Target
Mr. Dao Hoang Ho

Investigation of Terahertz Light Source by Implementation of Michelson Interferometry
Mr. Frederick Guy Wilson

May 1, 2008
1:00 pm (Thursday)

Dr. Juana Moreno
University of North Dakota

New magnetic materials for spintronics

Spin-based electronic (spintronic) devices utilize both carrier spin and charge to transmit or store information. Dilute magnetic semiconductors and organic magnets are promising spintronic materials. Research in my group focuses on developing a reliable theory of the magnetic, transport and optical properties of these compounds, with the ultimate goal of guiding experimental efforts in the search for optimal materials for spintronic device applications.