William and Mary

Spring 2014

January 24, 2014 (Friday) 4:00-5:00p.m. Small Hall 110
Speaker: Dr. Kei Moriya, Indiana University
Host: Prof. Wouter Deconinck
Title: Hadron Spectroscopy and What We Can Learn About QCD from GlueX 

Abstract: Quantum Chromodynamics, or QCD, is the force that binds quarks and gluons together to form bound states called hadrons. While the equations of QCD are rather simple, due to the strongly coupled nature at the GeV scale the spectrum of bound states is anything but simple. The upcoming GlueX Experiment at Jefferson Lab will explore the spectrum of hadrons and aims to expand our knowledge of hadron interactions and their connection with the underlying theory of QCD. The experiment will use a 9 GeV photon beam to produce many states of interest, and the large angular coverage of the detector will enable reconstruction of the multi-particle states produced. What can we learn from the spectrum of states, and how will this alter our understanding of how QCD works? Details of the experiment, what we expect to see, and some possible analyses involving strangeness will be discussed.

Januar 29, 2014 (Wednesday) 4:00-5:00p.m. Small Hall 110 (cancelled)
Speaker: Dan Millison, P.E., P.G./Transcendergy, L.L.C. 
Host: Prof. Gene Tracy
Title: "Saving the Forest and the Trees: A Conceptual Model of Sustainable Coal"

Abstract: The global debate on climate change mitigation has focused on the single tree of climate change, blinding most policy-makers to the broader forest of sustainability. Although coal is public enemy number one in the war on climate change, it will remain one of the single largest sources of global energy supply for the foreseeable future. Nevertheless, a successful outcome of negotiations for a post-2012 climate change treaty framework would include a long term objective of leaving coal in the ground.

As most policy-makers believe that leaving coal in the ground is an unrealistic scenario for the foreseeable future, carbon capture and storage (CCS) has attracted significant research and development in an attempt to achieve some semblance of carbon neutrality. Commercially viable-CCS presents a potential moral hazard: solving the CO2 disposal problem will encourage greater use of coal, without addressing the upstream environmental and social impacts of coal mining, transport, and downstream waste disposal. Clean coal as currently envisioned supercritical power with CCS bolted on is not sustainable. CCS as end-of-pipe disposal is a non-starter in the absence of a robust regulatory framework for waste management including carbon pricing.

Bypassing the dual challenges of making coal too expensive or making low-carbon energy too cheap to meter, there is an intermediate solution to render coal more sustainable. Sustainable coal - not to be confused with clean coal is possible by combining underground coal gasification (UCG, with the produced gas used in combined-cycle gas turbine power plants or other off-the-shelf systems including conversion to liquids) with carbon capture, reuse, and storage (CCR, preferably via carbonate mineralization or other utilization not involving additional hydrocarbon production). This end-to-end system is necessary to close the sustainability loop. UCG is not a new technology, having been deployed in the former Soviet Union more than 60 years ago.

There are several commercial UCG operations worldwide today, but it is not well-known even among energy specialists. UCG can remove most of the negative externalities associated with coal mining, transport, and conventional pollutant management. CCR would provide a positive market driver in place of a price on carbon. A commercially viable CCR system would also enable more sustainable exploitation of non-conventional gas resources (e.g., shale gas). An end-to-end system would facilitate the convergence of energy security and climate change objectives globally and particularly in developing countries which may rely increasingly on imported coal.

In the U.S., UCG offers the prospect of transforming the coal mining industry to a high-value added sector supporting next-generation power plants and coal-to-liquids production, at the same time facilitating exports of natural gas. 

February 14, 2014 (Friday) 4:00-5:00p.m. Small Hall 110
Speaker: Dr. D. Chris Benner, College of William & Mary
Host: Physics Chair David Armstrong
Title: Methane in the Outer Solar System: A Century and a Half Later
Abstract: In 1802 Wollaston first saw the solar spectral lines that Fraunhofer rediscovered in 1814. By the 1860s strong spectral features, later found to be due to methane, were found to dominate the spectra of all of the atmospheres of the outer solar system. There has followed a century and a half of efforts to first identify, then quantify these spectral bands which are essential to the study of the energy transfer, structure and chemical composition of the atmospheres. The bands in the visible and near infrared regions are so complex and the outer solar system physical conditions so extreme that it was thought that proper laboratory study was still at least decades away. However, a combination of the intracavity laser spectrometer of the University of Missouri at St. Louis and the College of William and Mary multispectrum nonlinear least squares spectrum fitting technique have determined the basic measurements for the 890 nm band. It is now possible to properly model an outer solar system atmosphere in this band.

February 21, 2014 (Friday) 4:00-5:00p.m. Small Hall 110
Speaker: Mordecai Feingold, Caltech
Host: Prof. Marc Sher
Title: Newton and the Origin of Civilization

Abstract: Isaac Newton's Chronology of Ancient Kingdoms Amended, published in 1728, one year after the great man's death, unleashed a storm of controversy. And for good reason. The book presented a drastically revised timeline for ancient civilizations, contracting Greek history by five hundred years and Egypt's by a millennium. Newton and the Origin of Civilizationseeks to reconcile Isaac Newton the rational scientist with Newton the theologian, alchemist, and chronologist, by illuminating on the manner in which he strove for nearly half a century to rectify universal history by reading ancient texts through the lens of astronomy, and to create a tight theoretical system for interpreting the evolution of civilization on the basis of population dynamics.  

March 14, 2014 (Friday) 4:00-5:00p.m. Small Hall 110
Speaker: Wally Melnichuk, Jlab 
Host: Prog. K. Orginos
Title: Nucleon structure from global QCD analysis of parton distributions
Abstract: Global QCD analysis of data from high-energy scattering reactions has provided considerable information about the momentum and spin distributions of quarks and gluons (partons) inside the nucleon. We review the current status of parton distribution functions (PDFs) of the nucleon, with particular focus on the region of large parton momentum fractions x. We also anticipate how future facilities, with fixed-target and collider experiments, may impact our knowledge of PDFs and reduce their uncertainties.

March 28, 2014  (Friday) 4:00-5:00p.m. Small Hall 110
Speaker: Margaret Murnane (JILA), William Small Distinguished Lecture
Host: Prof. Erlich
Title: Science at the Timescale of the Electron: Ultrafast X-Rays and Applications

Abstract: Ever since the invention of the laser over 50 years ago, scientists have been striving to create an x-ray version of the laser. The x-ray sources we currently use in medicine, security screening, and science are in essence the same x-ray light bulb source that Rontgen discovered in 1895. In the same way that visible lasers can concentrate light energy far better than a light bulb, a directed beam of x-rays would have many useful applications in science and technology. The problem was that until recently, we needed ridiculously high power levels to make an x-ray laser. The first successful x-ray laser experiments were, in fact, powered by nuclear detonations as as part of the star wars program in the 1980s. To make a practical, tabletop-scale, x-ray laser source required taking a very different approach that involves transforming a beam of light from a visible laser into a beam of x-rays. The story behind how this happened is surprising and beautiful, highlighting how powerful our ability is to manipulate nature at a quantum level. Along the way, we also learned to generate the shortest strobe light in existence - fast enough to capture even the fleeting dance of electrons in the nanoworld. This new capability shows promise for next-generation electronics, data and energy storage devices, and future medical diagnostics. (Popmintchev et al, Science 336, 1287 (2012))

April 4, 2014 (Friday) 4:00-5:00p.m. Small Hall 110
Speaker: Aron Bernstein, MIT
Host: Prof. Deconinck
Title: Experimental Tests of  QCD Symmetries with Pions 
Abstract: We are entering a new era in which we can test confinement scale QCD in some well chosen reactions such as  pi-pi and pi-N  scattering, pion properties, and electromagnetic pion production from the nucleon.

Based on the spontaneous breaking of chiral symmetry, chiral perturbation theory (ChPT) is believed to approximate confinement scale QCD as demonstrated by increasingly accurate  lattice calculations, particularly in pi-pi scattering. A pedagogical introduction to this area will be presented with special focus on recent, Increasingly accurate, experiments in electromagnetic pion production experiments from the proton; these test ChPT calculations and their energy region of validity. The connection between electromagnetic  pion production, pi-N scattering, and quark mass effects will be illustrated.

April 11, 2014 (Friday) 4:00-5:00p.m Small Hall 110
Speaker: Jeff Urbach, Georgetown University
Host: Prof. Irina Novikova
Title: Nonlinear mechanics of stiff biopolymer networks
Abstract: Disordered networks of stiff or semi-flexible filaments display unusual mechanical properties, including dramatic stiffening when sheared. Why do these materials differ from ordinary polymeric materials, like rubber or other plastics, which show linear elasticity over a wide range of strains? This talk will provide an overview of the mechanics of polymer networks and introduce the technique of Boundary Stress Microscopy, which adapts the approach of traction force microscopy, normally applied to study forces in living cells, to quantify the non-uniform surface stresses in sheared soft material. Unlike homogeneous continuous solids, some disordered granular materials show heterogeneous propagation of externally applied stresses along localized linear chains. Might similar stress heterogeneity be an important aspect of the mechanics of biopolymer networks? Our measurements on gels of the biopolymer collagen, a major component of the extracellular matrix that provides mechanical support in tissues, show stress variations over length scales much larger than the mesh size of the collagen network. These results show the power of Boundary Stress Microscopy to reveal the nature of stress propagation in disordered soft materials, which is critical for understanding many important mechanical properties, including the ultimate strength of a material and the nature of appropriate microscopic constitutive equations.

April 18, 2014 (Friday) 4:00-5:00p.m. Small Hall 110
Speaker: Erhai Zhao, George Mason University
Host: Prof. Rossi
Title: Quantum Matter at Extreme Cold
Abstract: Cooling and probing matter at low temperatures has been a major driving force for condensed matter physics. It is a proven, powerful way to force nature to reveal its organizing principles for quantum many body systems. The lessons learned from low temperature physics such as symmetry breaking and topological order have permeated into the lexicon of other branches of physics and led to prototypical applications such as superconducting qubits. In this talk, I will briefly review the well known macroscopic quantum phenomena of superconductivity and superfluidity occurring from hundred kelvin to millikelvin, and then highlight a few milestone achievements of quantum gases of alkaline atoms which have pushed the temperature record from microkelvin, through nanokelvin, and now down to tens of picokelvin. Then I will focus on recent experimental progresses in producing quantum gases of molecules with electric dipole moments, and atoms with large magnetic dipole moments. Finally, I will present our theoretical results regarding novel quantum phases of matter in dipolar Fermi gases.

April 25, 2014 (Friday) 4:00-5:00p.m. Small Hall 110
Speaker: DrKaren Gibson
Host: Prof. Tricia Vahle
Title: Searching for the Dark Matter of the Universe in South Dakota 
Abstract: The former Homestake gold mine in South Dakota has become a home to low-background science.  The LUX experiment is located at the 4850' level of the Sanford Underground Research Facility, located in Lead, SD.  I will present the first search for WIMP dark matter with the LUX detector, a time projection chamber using 300 kg of liquid xenon as a dark matter target, as well as the experimental program of the planned 7 ton LZ experiment.

May 2, 2014 (Friday) 4:00-5:00p.m. Small Hall 122
Speaker: Selim Shahriar, Northwestern University
Host: Prof. Irina Novikova
Title: New Tools for Precision Metrology: Superluminal Lasers and Atomic Ensembles with Ultra-High Compton Frequency
Abstract: Abstract: Precision metrology is the crown jewel of atomic, molecular and optical physics. It has played a key role in practical applications such as GPS, inertial navigation, and high speed communication. It has also played an important role in testing the fundamental laws of physics with ever increasing accuracy. In this talk, I will describe two new tools of precision metrology, with both practical and fundamental applications. First, I will describe the superluminal ring laser (SRL), inside which the group velocity of light may be as high as a million times larger than that of the vacuum speed of light, without violating causality or relativity. The SRL and related effects can be tailored to make ultra-sensitive sensors for practical applications, as well as for precision tests of General Relativity and detection of gravitational waves. Second, I will describe how interferometry at a Compton frequency as high as ten nonillion Hz (10^31 Hz) or a de Broglie wavelength as small as ten atto meter (10^-17 m) can be observed by measuring the collective states of an ensemble of a million non-interacting cold atoms, behaving as a single particle. I will describe how this process can be used to make novel types of atom interferometric gyroscope and accelerometers as well as atomic clocks, with enhancement in sensitivity over their conventional counterparts.