Seminars and Colloquia, July through December, 2010

• This Week's schedule.
• Earlier Semesters.
• Typical Week's schedule.
• July 5-9, 2010's schedule.
• July 12-16, 2010's schedule.
• July 19-23, 2010's schedule.
• July 26-30, 2010's schedule.
• August 2-6, 2010's schedule.
• August 9-13, 2010's schedule.
• August 16-20, 2010's schedule.
• August 23-27, 2010's schedule.
• August 30-September 3, 2010's schedule.
• September 6-10, 2010's schedule.
• September 13-17, 2010's schedule.
• September 20-24, 2010's schedule.
• September 27 - October 1, 2010's schedule.
• October 4-8, 2010's schedule.
• October 11-15, 2010's schedule.
• October 18-22, 2010's schedule.
• October 25-29, 2010's schedule.
• November 1-5, 2010's schedule.
• November 8-12, 2010's schedule.
• November 15-19, 2010's schedule.
• November 22-26, 2010's schedule.
• November 29-December 3, 2010's schedule.
• December 6-10, 2010's schedule.
• December 13-17, 2010's schedule.
• December 20-24, 2010's schedule.
• December 27-31, 2010's schedule.

Seminars and Colloquia, Typical Week:

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Physics Colloquium:

Journal Club on Statistical Mechanics, Condensed Matter Physics, and Optics (Informal):

Oklahoma State Physics Department

Seminars and Colloquia, July 5-9, 2010

No talks scheduled

Oklahoma State Physics Department

Seminars and Colloquia, July 12-16, 2010

No talks scheduled

Oklahoma State Physics Department

Seminars and Colloquia, July 19-23, 2010

No talks scheduled

Oklahoma State Physics Department

Seminars and Colloquia, July 26-30, 2010

No talks scheduled

Oklahoma State Physics Department

Seminars and Colloquia, August 2-6, 2010

No talks scheduled

Oklahoma State Physics Department

Seminars and Colloquia, August 9-13, 2010

No talks scheduled

Oklahoma State Physics Department

Seminars and Colloquia, August 16-20, 2010

No talks scheduled

Oklahoma State Physics Department

Seminars and Colloquia, August 23-27, 2010

First Week of Classes

No talks scheduled

Oklahoma State Physics Department

Seminars and Colloquia, August 30-September 3, 2010

Second Week of Classes

Physics Colloquium:

Abstract:

Let me begin an information sharing dialogue concerning demonstrations with some demonstrations that I find quick and easy, fun, insightful, and/or dramatic.  Included are demonstrations where faculty has (had) misconceptions, including myself.  Also shown are powerful web based applets and software that are easy to use and that helps students connect reality with abstraction in large classes.

Clearly there are educational benefits, when students experience real phenomenon, in addition to the purely abstract explanation given by the instructor.  Many more brain modules become activated and connected to a concept, when students describe what they experience, interpret the experience, explain it, and suggest how to test explanations or explore the phenomenon.  So, if you do demonstrations, you must at the least ask students what they observed. Answers may not be what you intended.

Demo Information: Professor Harmon continues to clean the “prep” room, introduce new demonstrations, and repair or replace old demonstrations.  He uses demonstrations extensively in Physics 1014 and will give a talk next week.  Professor Perk transferred videos of numerous demonstrations to CDs for easy use in all our classes.  I use demonstrations in most classes, even at the graduate level.  There are websites documenting both my collection of demonstrations and another for most of the demonstrations in the “prep” room.  Students tell me that demonstrations are uncommon in classes, yet demonstrations still prove meaningful beyond the introductory level.  As Richard Feynman said, “Never underestimate the joy of hearing (experiencing) something you already know.”

Question: Would you do more demonstrations, if it were an easier process? Perhaps we should discuss how to accomplish that goal? Professor A. Xie has made some suggestions.  Your comments will be important input to my committees this year.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3.00 PM. All students are welcome! Refreshments will be served.

Oklahoma State Physics Department

Seminars and Colloquia, September 6-10, 2010

Labor Day, Monday, September 6, 2010

Physics Colloquium:

Four Graduate Student Presentations:

Abstract: A significant obstacle to long-duration human space exploration is the risk posed by prolonged exposure to space radiation. This problem hinders, for example, the establishment of a permanent base on the surface of the Moon or a human mission to Mars. In order to keep mission costs at acceptable levels while simultaneously minimizing the risk from radiation to space crew health and safety, a judicious use of optimized shielding materials will be required. The use of plastic nuclear track detectors (PNTDs) is a proven and inexpensive method of passively measuring ionizing radiation. We have undertaken a comprehensive study using CR-39 PNTDs to characterize the radiation shielding properties of a range of materials at heavy ion accelerators. The study consists of analyzing CR-39 PNTD exposed in front of and behind shielding targets of varying composition and thickness relevant to the development and testing of materials for use in space radiation shielding.

Abstract: A matter-wave analogue of the optical Talbot effect can be realized by exposing an atomic wave packet to periodic pulses of a light grating. The mean energy of the diffracted orders displays a ballistic growth at a resonant time period, the Talbot time. These resonant peaks can be resolved at a rate faster than the limit imposed by the Fourier relation. Using a Bose-Einstein condensate, we have recently performed a measurement of the probability of revival of the initial state from these diffracted states. The width of such revival peaks, centered about the quantum resonance, was found to be narrower than would be expected from the Fourier theorem. Such an effect has implications towards high precision measurements of physical constants such as the fine structure constant and the local gravitational acceleration.

Abstract: Dissipation is generally thought to affect the quantum nature of the system in adverse manner, however we show that the dissipatively coupled nano systems can be prepared in states which beat the standard quantum limit of the mechanical motion. We show that the reactive coupling between the waveguide and the microdisk resonator can generate the squeezing of the waveguide by injecting a quantum field and laser into the resonator through the waveguide. The waveguide can show about 70–75% of maximal squeezing for temperature about 1–10 mK. The maximum squeezing can be achieved with incident pump power of only 12 μW for temperature about 1 mK. Even for temperatures like 20 mK achievable by dilution refrigerators, the maximum squeezing is about 60%.

Abstract: On simple metal (001) surfaces, there are two common mechanisms for adatom self-diffusion: atomic hopping and exchange. It has been observed experimentally that applying a high electric field could change the dominant mechanism between the two, thereby providing a possible means to control diffusion processes. For Pt adatom on Pt(001) surface, it was observed that the energetically favored mechanism changes from exchange to hopping when the applied field reaches a certain value. In this study, we use the empirical ES+EAM potential model to investigate the electric field effects on diffusion mechanisms for Pt/Pt(001) and Cu/Cu(001) . The calculated hopping and exchange barriers as functions of electric field are in good agreements with experimental observations.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3.00 PM. All students are welcome! Refreshments will be served.

Oklahoma State Physics Department

Seminars and Colloquia, September 13-17, 2010

Physics Colloquium:

Abstract:

The College of Arts and Science awarded the Department over $8,000 this summer for new demonstration materials for Physics.  In addition, Warren Grider and Mike Lucas’ shop have assisted in refurbishing existing demonstration materials for use in all courses, but especially the 1- and 2000 level courses.

Demonstrations in interference, color mixing, waves and vibrations, electricity and magnetism, nuclear radiation detection and other areas will be shown.  The accessibility of the demonstrations as well as HOW TO SET THEM UP will be shown.

Now, many demonstrations are hard (were hard) to use in classrooms like 141 or even 110.  Two (2) systems will be shown.  The first is a computer system that uses the overhead video projectors to show voltages, magnetic field strengths, optical spectra, forces, etc using a laptop computer and sensors.  The second is an excellent color video camera to use to project “smaller” demonstrations that are hard to see from over 10 feet onto the screen with the video projector!

Let’s face it—WAVING YOUR HANDS DOESN’T CUT IT.  And video clips, because of frauds on Facebook, U-Tube, etc are not reliable and the students know it!  Physics is a visual real-time activity.

Resources are available to help you become Mr Wizard in the classroom!

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3.00 PM. All students are welcome! Refreshments will be served.

Oklahoma State Physics Department

Seminars and Colloquia, September 20-24, 2010

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Physics Colloquium:

Abstract:

Here I present our experimental work creating a synthetic magnetic field in a Bose-Einstein condensate (BEC) generated by an abelian vector potential and discuss our progress towards creating non-abelian vector potentials, equivalent to spin-orbit coupling.

Ultra cold atoms are remarkable systems with a truly unprecedented level of experimental control and one application of this control is to engineer many body hamiltonians usually associated with condensed matter physics.  To date this engineering has focused mostly on the real-space potential that the atoms experience, for example, multiple-well traps, optical lattice potentials, or even potentials depending on the internal state of the atom.

We couple the internal states of rubidium 87 via a momentum-selective Raman transition and load our BEC into the resulting adiabatic eigenstates.  In agreement with theory, we observe that above a critical coupling strength our BEC acts as a charged Bose gas in the presence of a conventional vector potential.  Below this critical Raman coupling, the system has well defined spin degrees of freedom and acts like a spin-1/2 Bose gas with spin-orbit coupling.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3.00 PM. All students are welcome! Refreshments will be served.

Oklahoma State Physics Department

Seminars and Colloquia, September 27-October 1, 2010

No colloquium this week, as all cars have to leave central campus to make room for cars of football fans Thursday afternoon.

Oklahoma State Physics Department

Seminars and Colloquia, October 4-8, 2010

Pre-Colloquium Presentation:

Abstract:

Proteins are molecules in an organism which perform many functions like metabolism, sensing and communication. Proteins function and stability are highly influenced by the environment. Many proteins are water soluble and water is essential for protein function. Solutions with high salt concentration change the stability and solubility of proteins. Despite extensive studies, it remains unclear how salts alter the properties of proteins. We report the effects of different salts on the structural dynamics of photoactive yellow protein (PYP) which is an excellent model system. Time-resolved infrared difference spectroscopic technique is employed to capture the dynamic structural change of this protein upon light stimulation. Our data show that high salt concentration alters the proton transfer pathway and suppress protein conformational changes. We test different models to elucidate how high salts concentration change the structural response of PYP during its light sensing photocycle. The amount of conformational change of PYP is highly dependent on how much residue Glu46 of PYP has been protonated during its photocycle. We apply the electrostatic epicenter model to understand the dependency of conformational changes of PYP on Glu46 protonation. The knowledge gained may be applicable to understand the other effects of salts on proteins, which is known as the Hofmeister series.

Physics Colloquium:

Abstract:

Ultra-cold atom gases trapped in an optical lattice are now poised to make strong contributions to resolving outstanding questions in condensed matter physics.  In these experiments, atom gases are cooled to temperatures below a millionth of a degree of absolute zero and confined in a crystal of light.  I will talk about how we are using this system to simulate models relevant to dirty superconductors and highlight some recent results, including the first experiments in a fine-grained disordered lattice and the observation of a disorder-induced superfluid-to-insulator transition.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3.00 PM. All students are welcome! Refreshments will be served.

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Journal Club on Statistical Mechanics, Condensed Matter Physics, and Optics (Informal):

Talk is postponed until October 22 because of an unexpected tragic event.

Oklahoma State Physics Department

Seminars and Colloquia, October 11-15, 2010

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Physics Colloquium:

Abstract:

Atoms trapped in optical lattices are versatile systems that can be used to model many-body systems, as quantum computing resources, and for precision measurements. I will explain in general how such experiments work, and describe in particular our experiments at Penn State. The focus of the talk will be predominantly on 1D Bose gases, which can provide unique insights into the foundations of quantum statistical mechanics. Other experiments will also be mentioned, like trapping arrays of single atoms on the road to making a quantum computer.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3.00 PM. All students are welcome! Refreshments will be served.

Student’s Fall Break, Friday, October 15

Oklahoma State Physics Department

Seminars and Colloquia, October 18-22, 2010

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Abstract:

We propose the complex group theoretical Clebsch–Gordan coefficients as a novel origin of CP violation. This is manifest in our model based on SUSY SU(5) combined with the double tetrahedral group, T′, as the family symmetry. Due to the presence of the doublet representations in T′, there exist complex CG coefficients, leading to explicit CP violation in the model, while the Yukawa couplings and the vacuum expectation values of the scalar fields remain real. The tri-bimaximal neutrino mixing matrix arises from the CG coefficients of T′. In addition to the prediction for θ₁₃ ∼ θ_c/(3√2), the model gives rise to a sum rule, tan²θ_sol ∼ tan²θ_sol,TBM + ½ θ_c cosδ, which is a consequence of the Georgi–Jarlskog relations in the charged fermion sector. The predicted leptonic Dirac CP phase, δ, gives the correct value of the solar mixing angle, and the predicted CP violation measures in the quark sector are consistent with the current experimental data. With flavor effects included, sufficient amount of baryon number asymmetry can be obtained through leptogenesis. Since the Dirac CP phase is the only non-vanishing phase predicted in the lepton sector, there is a connection between leptogenesis and low energy leptonic CP violating processes in our model.

Physics Colloquium:

Abstract:

The origin of fermion mass hierarchy and mixing still remains one of the great mysteries in particle physics. Even though the fermion masses are generated by the Higgs mechanism, the Higgs mechanism by itself does not explain the observed mass hierarchy and mixing patterns. The observation of non-zero neutrino masses leads to yet another puzzle: why the neutrino masses are so small when compared to other fermions, and why two of the three neutrino mixing angles are so large when compared with their quark counterpart. There have been several theoretical ideas based on supersymmetric grand unification combined with a family symmetry to explain these aspects. In this talk, I will present a grand unified model based on supersymmetric SU(5) combined with the double tetrahedral group as a family symmetry, which predicts realistically all 22 masses and mixing angles of all observed fermions, including the neutrinos, with only 9 parameters. Due to the presence of the complex group theoretical Clebsch-Gordon coefficients, CP violation is entirely geometrical in origin, which leads to interesting implications for the generation of the matter antimatter asymmetry in the Universe.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3.00 PM. All students are welcome! Refreshments will be served.

Journal Club on Statistical Mechanics, Condensed Matter Physics, and Optics (Informal):

Oklahoma State Physics Department

Seminars and Colloquia, October 25-29, 2010

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Talk postponed because of illness of the speaker.

Physics Colloquium:

Abstract:

Optical forces are generally thought to be too weak for practical use. This picture changes when applied to lightweight nanoscale devices. In this talk, we demonstrate that significant optical force can be produced by a single pass of light in a silicon photonic circuit. This optical force, originated from lateral photon confinement rather than from momentum transfer, is applied in a planar geometry and offers high scalability. Control and harnessing optical force will allow fully integrated optomechanical systems on a chip, and open doors to a range of applications.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3.00 PM. All students are welcome! Refreshments will be served.

Oklahoma State Physics Department

Seminars and Colloquia, November 1-5, 2010

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Physics Colloquium:

Abstract:

The standard model of particle physics has been one of the greatest scientific achievements of the 20th century. Nevertheless most particle physicists think that the model is not complete. The generation of mass is included in an ad-hoc way, which does not even seem to be stable under quantum corrections. In this talk I first review the standard model and the Higgs mechanism thought to be responsible for particle masses. Then I explain the origin of the uneasiness with this idea. In the bulk of the talk I will present several ideas that could complement the standard model, including supersymmetric and extra dimensional models, and explain how the mass generation mechanism is incorporated/affected in such models.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3.00 PM. All students are welcome! Refreshments will be served.

Chemistry Department Seminar:

Abstract:

Single-walled carbon nanotubes (SWCNTs) are artificial nanostructures of interest to basic and applied researchers because of their remarkable mechanical, thermal, electronic, and optical properties. SWCNTs are formed in a variety of well defined structures, most of which have semiconducting band gaps that depend on nanotube diameter and roll-up angle. The 2002 discovery and interpretation of near-infrared band gap photoluminescence (fluorescence) from semiconducting nanotubes have led to a wide range of studies, some of which will be briefly surveyed here.

In one topic, near-IR spectrofluorimetry has proven to be a powerful tool for characterizing the compositions of mixed SWCNT samples. We have developed custom-designed instrumentation and software that permits rapid and sensitive fluorimetric analyses. In order to extend this method to find quantitative structure distributions, we have made calibrated photometric measurements on individual nanotubes representing 31 different semiconducting forms. The resulting fluorescence action cross-sections show significant structural variations in fluorescence brightness among nanotubes and provide the calibration factors needed to deduce relative concentrations from measured fluorescence intensities. Near-IR fluorescence microscopy has also been used to monitor stepwise changes in nanotube emission intensity as individual nanotubes undergo single-molecule sidewall reactions. Analysis of these steps reveals that the excitons formed by light absorption have high diffusional mobility, with each exciton visiting an average of ∼10,000 carbon atoms during its lifetime. Significant progress in sorting mixed SWCNT samples by structural form has been achieved through a nonlinear variant of density gradient ultracentrifugation. Samples enriched in ten different species have been prepared, and separation of the left-and right-handed SWCNT enantiomers has also been achieved in several cases. By using structurally purified samples, we have recently prepared a new type of chemically modified SWCNT in which sparse oxygen doping causes systematic and useful changes in optical properties. Finally, near-IR fluorescence has the potential to be a valuable tool in developing SWCNT biomedical applications. Nanotubes can be optically detected with high sensitivity and selectivity in cells, tissues, and even living organisms.

Note: Refreshments will be served in PSI 117.

Oklahoma State Physics Department

Seminars and Colloquia, November 8-12, 2010

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Abstract:

We consider the production of a light non-standard model Higgs boson of order 100 GeV with an associated W boson at CERN Large Hadron Collider. We focus on an interesting scenario that the Higgs boson decays predominately into two light scalars χ with mass of few GeV which sequently decay into four gluons, i.e. h → 2χ → 4g. Since χ is much lighter than the Higgs boson, it will be highly boosted and its decay products, the two gluons, will move close to each other, resulting in a single jet for χ decay in the detector. By using electromagnetic calorimeter-based and jet substructure analyses, we show in two cases of different χ masses that it is quite promising to extract the signal of Higgs boson out of large QCD background.

Physics Colloquium:

Abstract:

The collective behavior of a many-body system near a continuous phase transition is insensitive to the details of its microscopic physics. Characteristic features near the phase transition, called critical phenomena, are that the thermodynamic observables follow generalized scaling laws. The Berezinskii-Kosterlitz-Thouless (BKT) phase transition in two-dimensional Bose gases, for example, presents a particularly interesting case because the marginal dimensionality and intrinsic scaling symmetry result in a broad fluctuation regime which manifests itself in an extended range of scale invariant and universal behavior. We report the observation of a global invariance of scale and a universal description of 2D gases based on direct in situ optical imaging. The extracted universal thermodynamic functions confirm the wide critical regime near the BKT phase transition, provide a sensitive test to Monte Carlo calculations, and point toward a growing density-density correlations in the critical regime. Our assay raises new perspectives to explore further universal phenomena in the realm of quantum critical physics near a quantum phase transition.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3.00 PM. All students are welcome! Refreshments will be served.

Oklahoma State Physics Department

Seminars and Colloquia, November 15-19, 2010

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Joint Physics and Chemistry Colloquium:

Abstract:

The operating hypothesis of much of our current work is that atomic motion, over broad time scales (femtoseconds to milliseconds, the latter being the time scale of most enzyme catalyzed reactions), contributes to enzymic catalysis in proteins. It is clear from our work that specific types of motions are important in binding of ligands to proteins and transition state formation in enzymatic catalysis. Since new experimental and theoretical approaches are needed to understand the dynamical nature of proteins broadly and enzymatic catalysis specifically, we have employed time-resolved ‘pump-probe’ spectroscopic techniques because of the sensitivity of these type of approaches to all relevant time scales. And we have also developed and applied new theoretical methods. The talk will focus on how lactate dehydrogenase brings about catalysis based on current experimental and theoretical studies.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3.00 PM. All students are welcome! Refreshments will be served.

Oklahoma State Physics Department

Seminars and Colloquia, November 22-26, 2010

Thanksgiving Break, November 24-26

Oklahoma State Physics Department

Seminars and Colloquia, November 29-December 3, 2010

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Physics Colloquium:

Abstract:

In the early 1990s, there were no objects that had been observed when beyond the orbit of Neptune, except for Pluto. Now there are over 1200 such objects known. The region of our solar system out past Neptune is often called the Kuiper Belt. I will review the discovery and interesting dynamical properties of the various classes of objects found in the Kuiper Belt. With Steve Tegler, of the Northern Arizona University, I have been observing Kuiper Belt objects with a wide range of optical telescopes for the past 15 years, trying to learn something about their physical properties. I will briefly summarize this work.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3.00 PM. All students are welcome! Refreshments will be served.

Oklahoma State Physics Department

Seminars and Colloquia, December 6-10, 2010

Prefinals Week

Physics Colloquium:

Abstract:

Proton therapy is an emerging radiation therapy modality and the number of proton facilities has been significantly increased recently. The purpose of this talk is to give an overview of proton therapy. I will first introduce the history, principles, and rationale of proton therapy. Then I will describe the technical aspects of proton therapy, including proton accelerator, treatment nozzle and beam delivery techniques. The three main beam delivery techniques, passive scattering, uniform scanning and pencil beam scanning, will be reviewed and their pros and cons will be compared. An update will be given on the new development of proton therapy systems, including the ProCure system in Oklahoma City and the Still River machine to be installed at the university of Oklahoma. Finally, issues, challenges and opportunities in proton therapy, such as neutron dose, range uncertainty and economic challenges, are to be discussed.

Note: The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3.00 PM. All students are welcome! Refreshments will be served.

Oklahoma State Physics Department

Seminars and Colloquia, December 13-17, 2010

Finals Week

Special Seminar:

Abstract:

Any measured properties of the objects are available because of interaction between a measuring instrument and a tested entity. When nanoobjects are measured their properties could be altered, if the instrument touches the matter. Uncertainty of the knowledge about the object increases in this case. Soft, “non-disturbing” characterization of the nanoobjects is preferable for needs of nanotechnologies.

The nanoobject could be characterized with properties (energy, flow) of electrons escaped from the tested item. To reach a non “disturbing” mode, emission of the electrons should be induced when an external energy to emit the electron is not enough to influence molecular/atomic couples of the tested object. Such the approach corresponds to the prethreshold emission, a mean free path of the emitting electron suiting nanodimensions.

The prethreshold emission is considered both to characterize electrical charge of the nanoobjects (organic, inorganic, bio, size depended effects) surface, its stability and to be in use for their practical applications as chemical, biochemical censors, detectors of radiation.

Note: Prof. Dekhtyar is being hosted by Dr. Akselrod

Oklahoma State Physics Department

Seminars and Colloquia, December 20-24, 2010

No talks scheduled

Oklahoma State Physics Department

Seminars and Colloquia, December 27-31, 2010

No talks scheduled

Last Updated: August 23, 2010.

This page was prepared by Helen Au-Yang and Jacques H.H. Perk.