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Department of Physics and Astronomy


Colloquia

These lectures feature speakers from around the country and globe. Each colloquium lasts about an hour and gives you a deeper understanding of the types of physics and astronomy researching going on around the world. 

January 2018 - Present

Dr. Laurie E. McNeil
Bernard Gray Distinguished Professor
Department of Physics and Astronomy
University of North Carolina at Chapel Hill
Chapel Hill, North Carolina

Abstract:
Members of the professoriate have a professional obligation to carry out our educational mission as effectively as possible (given the constraints of our circumstances), to maximize the benefit that students receive from our instruction.  As physicists, this obliges us to make use of research findings from cognitive science and physics education research.

In this presentation, I will describe how I used these findings to transform my own work in the classroom and to lead comprehensive change in teaching and learning in my department.  I will conclude with reflections on the elements that were crucial to the success of this institutional-scale transformation.

Dr. Megan Donahue, Professor
Department of Physics and Astronomy
Michigan State University
President of the American Astronomical Society

Abstract:
Most, if not all, of the galaxies in the universe host a supermassive black hole in the center.  The masses of these black holes are correlated with the masses of the galaxies, or at least with the masses of the "bulge" components of the galaxies.  Simulations of galaxy formation track how dark matter and baryons interact gravitationally, assembling the network of galaxies, clusters of galaxies, voids, and filaments that we observe today.  Using our current understanding of the mean density of baryonic matter and dark matter, and of the effects of the accelerated expansion/dark energy, we now have a pretty good idea about how the largest structures emerged from the nearly uniform sea of tiny fluctuations that we can see in the cosmic microwave background.  However, we demand more from these models.  We would like to be able to explain what we observe, and that means explaining why, for example, the baryons don't make more stars than they do, why galaxies of about the mass of that of the Milky Way are the best at forming stars (yet still underperform based on expectations), and why the mass of a central black hole is affected by the mass of its host galaxy.  The answers are all related.  I will discuss a framework for thinking and talking about these issues, a framework useful for framing useful questions to apply to the simulations and next observations, and plans for the next space observatory.

Dr. Monique Aller, Assistant Professor
Department of Physics and Astronomy
Georgia Southern University
Statesboro, Georgia

Abstract:

Interstellar dust grains comprise a relatively small percentage of the total galaxy mass, but they significantly impact both the appearance of the galaxy as well as many of the physical processes important for the formation of stars and evolution of the galaxy.  The physical properties of these dust grains, including their composition, size, shape, and spatial distribution may vary both within a galaxy and from galaxy-to-galaxy.  Absorption lines in the spectra of distant quasars whose sightlines pass through foreground galaxies provide a valuable tool to simultaneously probe the dust and gas compositions of the interstellar medium in both local and more distant galaxies.

I will discuss two ongoing collaborative research programs exploiting archival multi-wavelength data to explore the silicate and carbonaceous dust grain properties in galaxies probed by quasar absorption systems.  I will present results from our work using Spitzer Space Telescope infrared spectra to study interstellar silicate dust grain properties in both local and distant quasar absorption systems and discuss our findings that silicate dust grain properties in distant galaxies can differ relative to one another and relative to those in the Milky Way.

Dr. Massimiliano Di Ventra, Professor
Department of Physics
University of California, San Diego
La Jolla, California

Abstract:
It is well known that physical phenomena may be of great help in computing some difficult problems efficiently.  A typical example is prime factorization that may be solved in polynomial time by exploiting quantum entanglement on a quantum computer.  There are, however, other types of (non-quantum) physical properties that one may leverage to compute efficiently a wide range of hard problems.  In this talk, I will discuss how to employ one such property, memory (time non-locality), in a novel physics-based approach to computation:  Memcomputing.  As examples, I will show the efficient solution of prime factorization, the search version of the subset-sum problem, approximations to the Max-SAT, and the ground state of Ising spin glasses, using self-organizing logic gates, namely gates that self-organize to satisfy their logical proposition.  I will also show that these machines take advantage of the long-range order that develops during their transient dynamics in order to tackle the above problems and are robust against noise and disorder.  The digital memcomputing machines we propose can be efficiently simulated, are scalable, and can be easily realized with available nanotechnology components.  Work supported in part by MemComputing, Inc. (www.memcpu.com) and CMRR.

Dr. Di Ventra's visit to USC is supported by the Office of the Provost's Visiting Scholars Grant Program.

Dr. Leonid Pryadko, Professor
Department of Physics and Astronomy
University of California, Riverside
Riverside, California

Abstract:
I will give an elementary overview of the current state of the art in quantum error correction, one of the key enabling technologies for scalable quantum computation.  How is it possible to protect a superposition state with continuously varying complex coefficients?  How will fault-tolerant quantum error correction work in practice?  What is it that commercial companies are trying to achieve in this field?  And what are the major open questions in theory, experiment, and architecture of quantum computers?

Dr. Oleg Tchernyshyov, Professor
Department of Physics and Astronomy
Johns Hopkins University
Baltimore, Maryland

Abstract: 
Magnets host a variety of solitons that are stable for topological reasons:  domain walls, vortices, and skyrmions, to name a few.  Because of their stability, topological solitons can potentially be used for storing and processing information.  This motivates us to build economic, yet realistic models of soliton dynamics in magnets (e.g. a domain wall in a ferromagnetic wire can be pictured as a bead on a string, which can move along the string and rotate about its axis).  Its mechanics is counterintuitive:  it rotates when pushed and moves when twisted.  I will review basic models of magnetic solitons in one and two dimensions, including classic examples as well as new results.

Dr. Ashot Gasparian, Professor
Department of Physics
North Carolina A&T State University
Greensboro, North Carolina

Abstract:
Two new extremely high precision measurements of the proton rms charge radius performed in 2010-2012 with muonic hydrogen atom demonstrated up to six standard deviations smaller values than the accepted average from all previous experiments performed with different methods on regular hydrogen.  This discrepancy triggered the well known "proton radius puzzle" in hadronic physics for the last several years.  To address this puzzle, the PRad collaboration in May-June 2016 performed a novel magnetic-spectrometer-free ep-scattering experiment in Hall B at Jefferson Laboratory accumulating high statistics and a rich experimental data set.  The specifics of the PRad experiment and the preliminary physics results, including the extracted proton radius, will be presented and discussed in this talk.

Dr. Raul Briceno, Assistant Professor
Department of Physics
Old Dominion University
Joint Theory Staff Member at Jefferson Laboratory
Norfolk, Virginia

Abstract:
At the core of everyday matter is a complex inner world of subatomic particles.  In particular, the nuclei of atoms are made of protons and neutrons, which are themselves made of even smaller particles known as quarks and gluons.  Thanks to experiments, like the ones being carried out at Jefferson Lab, we have been able to peer inside and deduce the guiding principles for the behavior of quarks and gluons.  This knowledge has been formalized into a fundamental theory of the strong nuclear force, Quantum Chromodynamics (QCD).  However, despite having the theory in place for over 40 years, the connection between QCD and experiment has been historically limited by the fact that the strong nuclear force is "strongly interacting."  In this talk, I will discuss recent theoretical progress that is finally allowing us to directly extract the same observables from QCD that are measured in experiment.

Dr. Alexander Monin
Maître Assistant at the University of Geneva
Geneva, Switzerland

Abstract:
Despite undoubted success of the Standard Model of particle physics, we are absolutely certain that it cannot be the ultimate theory of nature.  Several experimental puzzles indicate that there should be new particles.  Two scenarios for why new physics does not currently manifest itself at accelerators are either new particles are too heavy or they are light, but very weakly interacting with the Standard Model particles.  The two scenarios lead to deep theoretical questions.

In this talk, I will present what these questions are and will discuss how non-perturbative methods in quantum field theory may help to address them.


Dr. Karen Livesey, Associate Professor
Department of Physics and Energy Science
University of Colorado at Colorado Springs
Colorado Springs, Colorado

Abstract: 
Magnetic nanoparticles are used as drug-delivery systems, to kill cancer tumors by heating, and even to self-assemble optical diffraction gratings.  There are many open questions about how the magnetization of these nanoparticles relaxes, both for individual particles and when they strongly interact with one another.

In the first half of this talk, I will discuss a new analytic method [1] to fit the magnetization versus temperature measurements of non-interacting particles, which leads to a dramatic reinterpretation of some literature results.  In the second half of the talk, I will describe Langevin simulations of strongly interacting magnetic nanoparticles in fluids and show some of the exotic and varied dynamics that can result.  This is important because a small change in the fluid environment can lead to large differences in the nanoparticle efficacy for the biomedical and technological applications that are listed above.

[1] Livesey, KL, Ruta S, Anderson NR, Baldomir D, Chantrell RW, and Serantes D.  "Beyond the blocking model to fit nanoparticle ZFC/FC magnetisation curves."  Scientific reports 8, 11166 (2018).

Bio:  Karen Livesey is the first female Associate Professor of Physics in the University of Colorado at Colorado Springs' 53-year history.  She is an award-winning teacher and theoretical physicist who specializes in studying nano-magnets.  Karen received her Ph.D. in 2009 from the University of Western Australia.  Her research is supported by the U.S. National Science Foundation and the U.K. Royal Society.  She is a 2018-2019 Emmy Noether Fellow at the Perimeter Institute for Theoretical Physics in Canada.

Dr. Andrey Katz
Long-Duration Staff at CERN
Professor Titulaire at the University of Geneva
Geneva, Switzerland

All currently observed phenomena are consistently explained by the Standard Model (SM) of particle physics.  However, there are good reasons, both experimental and theoretical, to consider Physics Beyond the SM at the TeV scale.  The SM violates the principle of naturalness, which is a fundamental theoretical problem.  I will explain this problem and discuss experimental strategies for testing some of its possible solutions.

Abstract: 
One is a popular scenario, supersymmetry, which involves a major extension of space-time symmetry and manifests itself in new particles with SM charges at collider.  Another solution that I will discuss is the Twin Higgs, which in general predicts sterile particles at colliders.  Remarkably, I will demonstrate that it also gives rise to observable signals.  Both supersymmetry and the twin Higgs scenario have their own challenges and I will present novel strategies for both of these scenarios.  The SM alone cannot account for observed matter-antimatter symmetry and requires new physics.  I will analyze the possibility of generating the baryon asymmetry during the Electroweak phase transition and show that this idea can be probed at the LHC and future colliders via higgs precision measurement.  I will also present a novel mechanism for generating the baryon asymmetry at temperatures below the electroweak temperature, which can be probed via the gravitational wave signals in future interferometers.

Finally, the SM does not have a dark matter candidate, but it can naturally be accommodated by certain extensions of the SM at the TeV scale.  I will review some of these scenarios and emphasize the experimental signatures with an emphasis on the gravitational lensing.

Dr. Kimberly Boddy, Postdoctoral Fellow
Henry A. Rowland Department of Physics and Astronomy
Johns Hopkins University
Baltimore, Maryland

Abstract: 
There is overwhelming evidence for the existence of dark matter.  It plays a crucial role in the formation of structure in the Universe, yet little is known about its properties beyond gravitational effects.  In this talk, I will discuss the current and future prospects of understanding the fundamental nature of dark matter using observations in cosmology and astrophysics.  These observations offer glimpses into different cosmic eras that may shed light on the mystery of dark matter.

Dr. Igor Altfeder
Department of Physics
The Ohio State University
Columbus, Ohio

Abstract: 
Many-body interactions in quantum materials are important not only for condensed matter physics; they are also relevant to the phenomena in high energy physics, cosmology, and biological physics.  Our approach for studies of nanoscale interactions is based on scanning tunneling microscopy (STM).  This presentation will describe the STM experiments with quasi-freestanding layers of two-dimensional semiconductor WSe2.  They revealed the existence of room-temperature optical phonon condensate mediated by phonon scattering and interactions at resonant defects.  The real space Bose-Einstein condensation manifests itself in synchronization of phonon phases and formation of collective condensate phase with unusually large, macroscopic coherence time.  This coherent state of matter plays an important role in biological physics where it is known as Frohlich condensation.

Remarks by Dr. Ralf Gothe, Dr. Frank Avignone, Dr. Richard Creswick, etc.

Abstract: 
This colloquium will be devoted to the memory of Professor Horacio Farach, a long time and distinguished member of our faculty, who passed away on December 29, 2018.  Professor Farach came to USC in 1967 as a Visiting Professor following a brutal military coup in his home country of Argentina.  On July 29, 1966, the "night of the long sticks," hundreds of students and faculty of the University of Buenos Aires were attacked by police wielding batons and arrested.  About 1,400 faculty resigned in protest and 300 went into exile.  Many of these exiled professors found positions in the U.S. and so Horacio came to South Carolina.

Professor Farach was tenured at Associate Professor in 1968 and had a distinguished career at USC, winning the Russell Research Award, the Jesse W. Beams Medal of the APS, and several high-level international honors, including the presidential level Luis Leloir Medal of Argentina (1966) and the "Mayores Notables Argentinos" awarded by the National Assembly of Argentina (similar to the U.S. Medal of Freedom) in 2013.  In addition, he won three teaching awards at USC.  He served as Graduate Director for 18 years and as both Assistant and later Associate Department Chair of our department under Frank Avignone.  There were many interesting turns of events in his life that will make this lecture interesting.  He was a dynamite personality packed tightly into 150 pounds.  He will be missed by his friends, family, and many students.

Dr. Yanwen Wu, Assistant Professor
Department of Physics and Astronomy
University of South Carolina

Abstract: 
The 2018 Nobel Prize in Physics celebrates the invention of two important tools in optics:  the optical tweezers and the chirped-pulse amplification (CPA) technique.  The prize is shared by three physicists:  Donna Strickland (CPA), Gerard Mourou (CPA), and Arthur Ashkin (optical tweezers).  I will give a brief history of the development of tools made of light and provide an overview of the physics behind these latest additions to the light toolbox and their amazingly broad applications in areas ranging from basic research to everyday life.
 
 
Prof. Valery Nesvizhevsky, Staff Scientist
Science Division
Institute Laue-Langevin (ILL)
Grenoble, France

Abstract:
Gravitational quantum states (GQS) are traps for ultracold massive particles with gravity on top and a specularly reflecting mirror with a sharply changing surface potential on bottom.  Ultralow energies make this system very sensitive to any tiny interactions and large sizes simplify the experimental techniques.  GQS was discovered in experiments with ultracold neutrons (UCN) in 2002 and since then, they are actively used by several research groups (qBounce, Tokyo, GRANIT) at ILL, Grenoble.

While repulsive neutron-nuclei optical potential of many materials totally reflect UCN from surfaces, attractive van der Waals/Casimir-Polder potentials can also reflect ultracold atoms and molecules at surface due to quantum reflection.  In contrast to the case of neutrons, nobody has ever observed GQS of atoms and antiatoms.  GQS and a related phenomenon of Centrifugal Quantum States (CQS) of these particles is a sensitive method for the searches for extra short-range forces arising due to yet undiscovered light bosons or other phenomena beyond the Standard Model, manifestations of extra dimensions or dark matter.  The techniques developed within GQS studies promise to help achieving ultralow energies of H thus providing unprecedented conditions for optical and hyperfine spectroscopy of H with ultimate precision, which will be pursuit within the GRASIAN project.

Ms. Lisa Hunter and Mr. Rafael Palomino
Institute for Scientist and Engineer Educators (ISEE)
University of California Santa Cruz
Santa Cruz, California

Abstract:
The Institute for Scientist and Engineer Educators (ISEE) has been working with the science, technology, engineering, and mathematics (STEM) community since 2001 to prepare early-career scientists and engineers to become effective and inclusive in their teaching and mentoring.  At the heart of this work is the Professional Development Program (PDP), which provides graduate students and postdocs intensive training in teaching methods supported by research and a practical teaching experience with students at the undergraduate level.  More than 550 participants have now completed the program and have used the experience to obtain jobs, fellowships, and grants.  Participants become part of an enduring national community of scientists and engineers dedicted to effective and inclusive education.  ISEE was recently awarded a grant from the NSF, "Advancing Inclusive Leaders in Astronomy," with an NSF physics supplement, which provides support for graduate students and postdocs at ISEE chapters to participate in the PDP and for alumni at sites across the U.S. to lead and expand upon ISEE's prior work at their own institutions.  This presentation will include information about the PDP, including research projects related to PDP thematic elements and how they increase student performance in the classroom.

The University of South Carolina is ISEE's newest chapter, currently operating in the Physics and Astronomy department with Chapter Lead and PDP alumnus, Steven Rodney.  The USC chapter will send at least one new team to the PDP in Spring 2019 and we are actively seeking student and postdoc participants as well as faculty partners.
 
 
Dr. Sylvester Ekpenuma, Professor
School of Natural Sciences and Mathematics
Claflin University
Orangeburg, South Carolina

Abstract:
Defects and impurities in materials affect their properties.  For semiconductors, these can significantly affect their electronic and structrual properties.  Given their usefulness in device applications, there has been extensive research in defects and impurities in semiconductors in order to better understand various phenomena associated with their use.  Experimental identification and characterization are challenging as defects sometimes develop even in the best experimental conditions.  Theoretical modeling has emerged as a needed complement to experimental work and computational advances have led to reasonable and accurate results that can serve as predictive tools for defect identifications.  This presentation will review some theoretical defect modeling techniques and apply the special quasi-random structures approach for the study of defects in cadmium zinc telluride.

Dr. Arthur Hebard
Distinguished Professor of Physics
Member of the National Academy of Sciences
University of Florida
Gainesville, FL
 
Abstract:
The crystalline layered high-Tc superconductor Bi-2212 can be easily cleaved into smoothly faceted flakes, which, when placed into intimate physical contact with a variety of layered materials or bulk semi-conductors, form heterogeneous junctions.
 
Two such junctions are discussed in this talk.  Bi-2212/1T-TAS2, the 1T-TaS2 is a Mott insulator harboring charge density waves (CDWs) and Bi-2212/n-GaAs Schottky barrier junctions, which manifest quantum mechanical tunneling at low bias voltages.  The CDW order in the 1T-TaS2 appears to play an important role by coexisting with an unexpected and surprisingly high Tc of the induced proximity gap which, for junctions with high transparencies, is seen to have a surprisingly large value (~ 20 meV) equal to half that of intrinsic Bi-2212 (~ 40 meV).  Proximity-induced high-Tc superconductivity in the 1T-TaS2 is driven by coupling to the metastable metallic phase coexisting within the Mott commensurate (CCDW) phase and associated with a concomitant change of the CCDW order parameter in the interfacial region.  For the Bi-2212/n-GaAs Schottky barrier junctions, modifications to the thermionic emission equation provide an excellent description of the I-V characteristics even at low temperatures where tunneling is found by differential conductance spectroscopy measurements to be important and capacitance measurements under reverse bias suggest an unexpectedly long electric field screening length in the superconductor.
 
 
Dr. Marco Ajello, Assistant Professor
Department of Physics and Astronomy
Clemson University
Clemson, South Carolina
 
Abstract:
The light emitted by all galaxies across the history of the Universe is encoded in the intensity of the extragalactic background light (EBL), the diffuse cosmic radiation field at ultraviolet, optical, and infrared wavelengths.  The EBL is a source of opacity for high-energy γ rays via the photon-photon interaction (γγ --> e+e-), leaving a characteristic attenuation imprint in the spectra of distant γ-ray sources.
 
In this talk, I will report on unprecedented measurement of the EBL using data from the Large Area Telescope on board of Fermi, which has allowed us to measure the star-formation history and the density of faint galaxies during the re-ionization.
 
 
Dr. Luca Guazzotto, Associate Professor
Department of Physics
Auburn University
Auburn, Alabama
 
Abstract:
Nuclear fusion energy production has been the ultimate goal of an active field of research for several decades.  In addition to the technological and physics challenges that need to be overcome to achieve fusion energy production, some considerations at a macroscopic level are also necessary.  In particular, a precise energy balance needs to be satisfied in order to achieve net energy production.  The so-called "Lawson criterion," derived from the original work by Lawson in 1957, has been for decades the de-facto standard of our understanding of energy balance in nuclear fusion reactors and experiments.
 
In this talk, we will review the basis for energy balance and power production in fusion devices and discuss the details of the Lawson criterion.  In the last part of the talk, we will highlight some of the recent improvement and extensions to the Lawson criterion that will allow us to gain a better understanding of the requirements for fusion energy production.
 
 
Dr. Pawel Mazur, Professor
Department of Physics and Astronomy
University of South Carolina
 
Abstract:
I will talk about superfluid universe, the ground state in quantum gravity, and gravastars.  Quantum mechanical considerations applied to the largest physical system in evidence have led to the understanding that there must exist such a thing as vacuum energy, which in its ground state should be homogeneous and isotropic, but in the presence of "impurities" (baryons), it will exhibit inhomogeneities.  Superfluid is a condensate.  Considering droplets of such a condensate, one arrives at the concept of a gravastar, the maximally supercompact material configuration consistent with the laws of graviation.  It just happens that such objects are abundant in the Universe.  There is one in the Center of the Milky Way galaxy known as the Sag A*, which has a mass of approximately 4.4 million Solar masses.  The Event Horizon Telescope (EHT), a planet-wide array of radio telescopes, will either refute or confirm predictions following from the gravastar theory of super-compact objects in our Universe in the next few years.

 
Dr. Frank Avignone, III, Carolina Endowed Professor of Physics and Astronomy
Department of Physics and Astronomy
University of South Carolina
 
Abstract:
The discovery that there was far more mass in galaxies than contained in visible material was made by Fritz-Zwicky in 1933.  He drew this conclusion by observing the motions of galaxies in the Coma Cluster and by applying the virial theorem.  He concluded that there was several hundred times more mass in the Cluster than could be accounted for by the mass in stars and dust.  He called this unobserved mass "Dunkel Materie" in his native Bulgarian language.  Following the publication of his results, there were a number of other observations that clearly support this conclusion.  We will review the other observations and then discuss the history of the experimental direct searches from the first one published in 1986, to the many efforts ongoing today.  In particular, the roles played by members of the USC Department of Physics and Astronomy in the past and present experiments will be discussed.
 
 
Dr. Nahum Arav, Professor
Department of Physics
Virginia Polytechnic Institute
Blacksburg, Virginia
 
Abstract: 
Quasar outflows are a prime candidate for producing various galactic-scale feedback processes:  explaining the relationship between the masses of the central black hole and the galaxy's bulge, and chemically enriching the Intra-cluster medium.  Using the Hubble Space Telescope, we observed the first sample of quasar outflows that covers the 500-1050 Angstrom rest-frame spectral region (XUV).  These observations are revolutionizing our understanding of the outflows and their influence on the host galaxy.  XUV coverage is the only way to probe the very high ionization phase that carries 90% or more of the outflowing material, and obtain the distances of each outflow from the central source.  The survey uncovered three outflows, which are likely to have the largest outflow kinetic-luminosity measured to date.
 
 
Dr. Yordanka Ilieva, Associate Professor
Department of Physics and Astronomy
University of South Carolina
 
Abstract:
Gluons mediate the strong interaction that binds visible matter and, together with quarks, are the building blocks of all hadrons.  Thus, the study of gluons is of fundamental importance for understanding the strong dynamics that gives protons, neutrons, and nuclei their basic properties.  Among the gauge bosons in the Standard Model, gluons are the only self-interacting particles.  The gluon self-interaction causes effects that are unique for strongly-interacting matter and are not observed in electroweak phenomena.  One such effect is confinement, meaning that no single quark or gluon can be observed in isolation.  The practical experimental consequence of confinement is that one cannot break a proton or a neutron into quarks and gluons and study these constituents directly.  Special imaging techniques need to employed in order to construct the three-dimensional maps of gluons in nucleons and nuclei and to explore the interactions between gluons and their contribution to the nucleon-nucleon force.  While deep inelastic inclusive reactions have been instrumental to study the longitudinal momentum distributions of gluons, the measurements of certain exclusive nuclear reactions allow to obtain information about how the gluons are distributed in space in a plane perpendicular to the parent nucleon or nucleus motion.
 
In this talk, we will present a program that is being carried out at Jefferson Lab to study the transverse gluon structure of proton, neutron, and deuteron in fixed-target experiments.  This is accomplished by scattering a photon beam off a fixed proton or deuteron target and detecting in coincidence an outgoing intact proton or deuteron and a J/y meson.  We will also discuss high-precision gluon imaging planned with the next large U.S. nuclear-physics installation, the Electron-Ion Collider (EIC).
 
 
Dr. Robin Shelton, Professor
Department of Physics and Astronomy
University of Georgia
Athens, Georgia
 
Abstract:
Sensitive observations have found enormous clouds of material beyond our Milky Way Galaxy.  Some are as large as mini-galaxies with as much mass as 100 million Suns.  Others are shreds that were ripped from nearby galaxies.  Additional observations show that several nearby clouds are currently interacting with our own Galaxy.  Some have reportedly shot through the Milky Way's disk while others are currently passing through the less dense outskirts of our Galaxy.  My group has been computationally modeling these clouds, called high velocity clouds (HVCs), in order to determine how they affect our Galaxy and how our Galaxy affects them.

In this presentation, I will show how HVCs behave on timescales of hundreds of millions of years, how they shed streamers of highly ionized gas that become incorporated into our Galaxy, and what happens when they collide with the dense gas in our Galaxy's disk.

Dr. Vincente Guiseppe, Assistant Professor
Department of Physics and Astronomy
University of South Carolina
 
Abstract:
Neutrinoless double-beta decay searches play a major role in determining the nature of neutrinos, the existence of a lepton number violating process, and the effective Majorana neutrino mass.  The MAJORANA Collaboration is operating its DEMONSTRATOR array of high-purity Ge detectors at the Sanford Underground Research Facility in South Dakota to search for neutrinoless double-beta decay in (76)Ge.  A similar experiment by the GERDA collaboration is operating at LNGS in Italy.  The first results from the MAJORANA DEMONSTRATOR's initial 10 kg-yr of exposure has set a half-life limit on the decay while an upcoming release of the unblinded data set is planned to reach 30 kg-yr of exposure.  The MAJORANA DEMONSTRATOR and GERDA experiments have achieved the lowest backgrounds and a superior energy resolution at the neutrinoless double-beta decay region of interest.  These results demonstrate that (76)Ge is an ideal isotope for a large next generation experiment.  Building on the successes of the MAJORANA DEMONSTRATOR and GERDA, the LEGEND collaboration has been formed to pursue a ton-scale (76)Ge experiment.  This talk will present the initial results from the MAJORANA DEMONSTRATOR' experiment, the plan for the LEGEND experiment, and the role the USC group is playing in the overall (76)Ge program.
 
 
Dr. Yanwen Wu, Assistant Professor
Department of Physics and Astronomy
University of South Carolina
 
Abstract:
Our universe is made up of particles ranging from the fundamental few, such as quarks, to a vast sea of composites and quasiparticles, such as atoms and excitons.  While there is still much to uncover on the fundamental level, properties of particles in the composite realm are well-identified and better understood because their interaction is mediated by the ubiquitous photon.  This knowledge provides researchers in the fields of atomic and condensed matter the tools to create and manipulate quasiparticles with a high degree of precision and versatility.

In this talk, I will discuss the properties of two specific types of quasiparticles (excitons and surface plasmon polaritons) in two different condensed matter systems (semiconductor and metal) and how they can be optically measured and manipulated for potential applications in quantum information processing and nanoscale photonic circuitry.
 
 
Dr. Dean Lee, Professor
Department of Physics and Astronomy
Michigan State University
East Lansing, Michigan
 
Abstract:
This is an introduction to how atomic nuclei and other quantum few- and many-body systems can be studied using lattice simulations.  The first part of the talk explains the basic formalism called lattice effective field theory.  The rest of the talk is a discussion of novel methods and the new physics insights one gains with each.  The methods discussed are the adiabatic projection method for scattering and reaction calculations, pinhole algorithm for probing structure and thermodynamic properties, and eigenvector continuation for extending calculations to regions of parameter space where things otherwise break down.
 
 
Prof. Sergey Alekhin
Deutsches-Elektronen-Synchrotron (DESY)
University of Hamburg
Institute for High-Energy Physics
Hamburg, Germany and Protvino, Russia
 
Abstract:
Results of the QCD analysis of a variety of the hard-scattering data is overviewed with a particular focus on determination of the quark distributions in the nucleon.  A potential of the recent precise data collected at the Large Hadron Collider (LHC) for the problem of quark species disentangling is discussed and compared to the impact of the low-energy fixed-target data alongside of modeling the heavy-quark contribution within various factorization schemes.  Finally, remaining challenges and potential improvements in the field are outlined.
 
 
Dr. Joseph E. Johnson
Distinguished Professor Emeritus
Department of Physics and Astronomy
University of South Carolina
 
Abstract:
For over 100 years, the dominant problem in theoretical physics has been the lack of integration of the theory of general relativity (GR) with quantum theory (QT) and the standard model (SM).  QT and the SM are built upon a non-commuting operator (Lie) algebra of fundamental observables for position, momentum, energy, angular momentum, charge, strangeness and other observables for describing atomic and nuclear level phenomena.  This algebra expresses the interference in the order of fundamental measurements. But GR is framed as nonlinear differential equations for the curved metric of space-time in a Riemannian Geometry (RG) without an operator algebra for its fundamental observables of space-time and of the metric.
 
It will be shown that the Einstein equations for GR as well as the underlying RG and can be reformulated as a generalized Lie algebra with a single assumption that generalizes the space-time metric to be a function of the position operators from quantum theory.  Since the metric is now an operator, this approach generalizes the framework of the underlying Heisenberg Lie algebra and consequently the Lorentz and Poincare algebras when gravitation is dominant.   The proposed integrated algebraic system is shown to give exactly the Einstein equations with large masses and dominant gravity (small h) and likewise to exactly give traditional QT and the SM frameworks when gravity is negligible.  Possible observable tests of this proposed integration and new results are discussed.  This approach also admits extensions to extra dimensions as with string theories.  However, some of the core problems of such an integration (renormalization, covariant GR gauge transformations and their merger with the SM Yang Mills theory) are not yet solved.  The presentation will end with a purely mathematical derivation of the foundations of RG based upon a generalized Lie algebra.
 
 
Dr. Alessandro Pilloni
Theory Center Postdoctoral Staff
Thomas Jefferson National Accelerator Facility
Newport News, Virginia
 
Abstract:
Although QCD is universally acknowledged as the theory of strong interactions, the way how the fundamental degrees of freedom (quark and gluons) arrange themselves into the observed hadrons is still a mystery.  Moreover, the presence of multiple states leads to intricate interference patterns that make the extraction of meaningful information challenging.

In this colloquium, I will discuss the role of amplitude analysis in converting the ra experimental data into robust physics information.  I will finally present some of the phenomenological models used to describe the features of the spectrum.
 
 
Dr. David B. Tanner, Professor
Department of Physics
University of Florida
Gainesville, Florida

Abstract:
The Axion Dark Matter eXperiment (ADMX) is conducting a search for axions within the dark-matter halo of our Galaxy.  The nature of the dark matter in the Universe, one of the most compelling questions in all of science, will be clarified by the results of this search.  Dark matter makes up roughly 85% of the mass in the universe and we don’t know what it is.  It interacts extremely weakly with the ordinary matter and energy in the universe, making detection very challenging.  Axions are a very well-motivated candidate for the dark matter.  Many would say these days that they are the best-motivated candidate.  Axions can be detected by their conversion to microwave photons in a strong magnetic field; this process is the basis of many searches for axions and axion-like particles.

The ADMX experiment employs a large-volume superconducting magnet, a high-Q tunable microwave cavity, an ultrasensitive SQUID microwave amplifier, and a high-performance dilution refrigerator to enable 100 mK temperatures for cavity and SQUID.  In the last year, this “Generation 2” ADMX detector has reached the sensitivity to detect axions even in the case where they are as weakly coupled as theory allows.  The ADMX detector, located at the University of Washington, has just completed its first run at this design sensitivity. There were no detections and the search continues with a second science run.  The resulting limits on axion mass, the prospects for the ongoing search, and the outlook for the future will be discussed.
 
 
Dr. Andrew B. Greytak, Assistant Professor
Department of Chemistry and Biochemistry
University of South Carolina
 
Abstract:
The behavior of 0, 1, and 2-dimensional nanoscale materials is strongly influenced by surface structure that is subject to exchange with the surrounding environment. Analysis of the surfaces of materials of different dimensionalities can require considerably different approaches, but common to all are shared concepts of charge balance, coordination chemistry, and crystallography; and shared goals and challenges in developing scalable approaches to sensors and optoelectronic devices. In this talk, I will focus on two areas of ongoing research in our lab.
 
In the first area, we are developing gel permeation chromatography as a multifunctional processor for purification and ligand exchange chemistry of a variety of compound semiconductor nanocrystals, including fluorescent quantum dots (QDs). GPC serves as a valuable tool in preparing ligand-exchanged quantum dots with diverse functions including water solubility, and in providing a well-defined initial state for thermodynamic investigations. I will emphasize the use of GPC to study ligand exchange through on-column reactions between QDs and small molecules. I will also discuss nascent efforts to improve understanding and performance of assembled QD films (nanocrystal solids) as solution-processable semiconductor materials.
 
In the second area, we are using functional imaging to study ligand association to semiconductor nanowires, host-guest interactions in 1D microporous crystals, and optoelectronic properties of epitaxial graphene/silicon carbide (EG/SiC)-based nanoelectronic heterostructures. I will emphasize recent results from scanning photocurrent microscopy on EG/SiC bipolar phototransistors.
 
 
Dr. Ronald D. Edge
Distinguished Professor Emeritus
Department of Physics and Astronomy
University of South Carolina
 
Abstract:
The Cavendish Lab, my old haunt, recently informed me that they were building their third generation.  Since I am of the first generation founded in 1871, I had better hurry up and tell about it.  My friend, GFC Searle, knew Clerk Maxwell, the first professor, personally.  Maxwell was very humorous, unlike his picture.  Searle also founded the V2 V Club.  I went there just after the war, when there was no heat.  Taking notes while wearing woolly gloves is not easy, even if lectures were from Bragg, Dirac, and Hartree (using the Schroedinger approach).  My research employed the 1 MeV Philips Cockcroft-Walton accelerator, which looked like something from Frankenstein and worked like that too.

Going to Australia in 1954, I re-built the Harwell electron synchrotron at the new Australian National University for photodisintegration.

Coming to USC in 1958, the department was converting from a teachers' training college to a research institution.  Unfortunately, the new department head had died in the summer, Tony French had inherited the job, and he invited me.  We commenced a Ph.D. program that year and acquired two graduate students. Theorists may only require pencil and paper, but experimentalists are more demanding.  The NSF gave us funds for research on cosmic ray neutrons, and a small accelerator, for which the state provided a building.  The first summer, the entire department camped there as it was the only building where air conditioning was available.  USC had an enrollment of 3,000 students at the time, which has now increased to approximately 50,000 between all state campuses.
 
 
Dr. Juan I. Collar, Professor
Kavli Institute for Cosmological Physics
University of Chicago
Chicago, Illinois
 
Abstract:
I will discuss the most recent results from PICO, a search for particle dark matter using rather unconventional bubble chambers.  I will then move on to COHERENT, an ongoing effort at ORNL's Spallation Neutron Source seeking to exploit the recently-measured coherent neutrino-nucleus scattering (CEvNS) as a new tool for neutrino physics.  The common ground between these two projects is the detection of keV and sub-keV nuclear recoils.  The challenges in developing and understanding detector technologies sensitive to these will be emphasized.