Oklahoma State Physics Department

Seminars and Colloquia, January through June, 1997

• This Week's schedule.
• Earlier Semesters.
• Typical Week's schedule.
• January 6-10, 1997's schedule.
• January 13-17, 1997's schedule.
• January 20-24, 1997's schedule.
• January 27-31, 1997's schedule.
• February 3-7, 1997's schedule.
• February 10-14, 1997's schedule.
• February 17-21, 1997's schedule.
• February 24-28, 1997's schedule.
• March 3-7, 1997's schedule.
• March 10-14, 1997's schedule.
• March 17-21, 1997's schedule.
• March 24-28, 1997's schedule.
• March 31-April 4, 1997's schedule.
• April 7-11, 1997's schedule.
• April 14-18, 1997's schedule.
• April 21-25, 1997's schedule.
• April 28-May 2, 1997's schedule.
• May 5-9, 1997's schedule.
• May 12-16, 1997's schedule.

Seminars and Colloquia, Typical Week:

Laser and Photonics Research Seminar:

Oklahoma High Energy Physics Seminar on Talk-Back Television:

Physics Colloquium:

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

Oklahoma State Physics Department

Seminars and Colloquia, January 6-10, 1997

No Seminars: Preliminary Exams

Oklahoma State Physics Department

Seminars and Colloquia, January 13-17, 1997

Physics Colloquium:

Abstract:

Recent Hubble Space Telescope images have rekindled interest in protoplanetary disks. These gaseous disks, which surround other stars and are often toroidal, are comparable in size to our own Solar System and may ultimately turn into planetary systems. I will discuss the protoplanetary disks found in the Orion Nebula in terms of theoretical models of disk structure.

Note:

The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3:30 p.m. All students are welcome! Refreshments will be served.

Oklahoma State Physics Department

Seminars and Colloquia, January 20-24, 1997

SPS Invitational Physics Colloquium:

Abstract:

NASA has had many well publicized successes and a few failures over the past two-and-a-half decades. A critical review of those efforts reveals underlying issues both within NASA and in the scientific/technical community. This review also demonstrates the tremendous amount of information that has been returned by NASA missions to the planets, and the ways that information has changed our view of the solar system. As we look toward the future, this information and the lessons learned from past efforts can guide us toward realistic goals and objectives for the space program. NASA's planned schedule for solar system exploration in the future is an ambitious and exciting one. It promises deeper understanding of the mysteries that remain in our understanding of the solar system.

Note:

The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3:30 p.m. All students are welcome! Refreshments will be served.

Oklahoma State Physics Department

Seminars and Colloquia, January 27-31, 1997

Undergraduate Physics Journal Club:

Abstract:

Pseudo-Science:

What is Science? What is pseudo-science? How can you tell the difference? Is anything possible? In this seminar we will look at various pseudo-science topics from astrology to the X-Files. The logical fallacies and attributions of pseudo-science will be discussed. Be prepared to discuss your favorite pseudo-science topic.

(You may pick up the reading material in Rm. 145 of PSII)

Physics Colloquium:

Abstract:

Seismic imaging has become an indispensable tool to the oil industry for finding and producing oil and gas reserves. As exploration for oil and gas has moved into areas of increasingly complex geology, research in the oil industry has focused on improving the accuracy of wave propagation computations and improving our understanding of earth properties. A major result of Phillips' advances in seismic imaging is the discovery of new oil reserves beneath and alongside complex salt structures in the Gulf of Mexico.

I will review seismic imaging fundamentals and show examples of the recent advances in imaging complex structures in the earth. I will conclude by discussing geophysics research opportunities in the oil industry.

Note:

The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3:30 p.m. All students are welcome! Refreshments will be served.

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

Laser and Photonics Research Seminar:

Abstract:

Surface Plasmon Spectroscopy (SPS) is based on the excitation of lateral vibrations of the electronic density at metal/gas or metal/liquid interfaces. Characteristics of an SPS peak is highly sensitive to the structure of the interface. As such, the presence of a deposited organic film of 0.5 nm in thickness can be detected by this method. While the effect of roughness of a metal substrate has been investigated theoretically and experimentally by several groups, SPS has been applied only to smooth deposited films, so far. In this study, we have demonstrated that parameters describing the roughness of films self-assembled on metals could be extracted from SPS spectra. A simple model in which the surface of a film is approximated by a "check board" has been applied. SPS roughness calculations have been compared with atomic force microscopy topographic images.

Coffee and cookies will be served at 3:45 p.m.

Oklahoma State Physics Department

Seminars and Colloquia, February 3-7, 1997

Laser and Photonics Research Seminar:

Abstract:

BSO and BGO are photorefractive materials of current interest for a number of applications. Their photorefractive response is governed in large part by an interesting center, anti-site Bi, which serves as the source of photo-electrons. This center which usually acts as a doner can also act as an acceptor. It is present in all melt-grown BSO and BGO. We have been able to confirm that the anti-site Bi center is the active center by "doping" it into hydrothermally-grown BSO where it is normally absent. The properties of this center will be discussed. It often controls the electronic properties of dopants added to tailor these materials for specific applications. Transition metal dopants provide a way to alter the response of BSO and BGO. Doping with chromium has led to the possibility of using BGO:Cr as a "permanent" holographic storage medium. The existence of strong gratings with lifetimes greater than 24 hours will be discussed.

Coffee and cookies will be served at 3:45 p.m.

Oklahoma High Energy Physics Seminar:

Physics Colloquium:

Abstract:

Educators often claim that it is vital to teach critical thinking. But this is quite difficult, and picking raw material to think about is tricky. Religion and politics offer fertile fields, but critical thinking along these lines tends to offend many. Pseudoscience, I'd like to claim, is familar to semi-literate students, and also has an inherent glamor and interest that makes it a fine corpus on which to practice critical thinking skills. Very little knowledge of science or general knowledge of any kind is required to find fatal flaws in almost all familiar fields of pseudoscience. Can pseudoscience, one of the major symptoms of the fact that most people can't think, really be used to teach thinking? I'll offer some personal insights gained in 15 years of teaching a course about pseudoscience.

Note:

The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3:30 p.m. All students are welcome! Refreshments will be served.

Oklahoma State Physics Department

Seminars and Colloquia, February 10-14, 1997

Undergraduate Physics Journal Club:

Abstract:

"Anybody who's not bothered by Bell's theorem has to have rocks in his head" --anonymous Princeton physicist

Bohr once suggested that the moon isn't there unless you're looking at it. Einstein rejected this view, replying that the notion of "spooky action at a distance" merely demonstrated that quantum mechanics is an incomplete description of the universe. What were these two great physicists arguing about? We'll examine this question, along with the theoretical analysis by J.S. Bell which paved the way for an experimental determination of who was right. Recent experiments have overwhelmingly supported Bohr's position; we'll look at some of the results, and discuss their practical implications.

(You may pick up the reading material in Rm. 145 of PSII)

Oklahoma High Energy Physics Seminar:

Physics Colloquium:

Abstract:

Exploration Geophysics provides a rich source of challenging physics/applied math problems. Exploration tools include seismic sounding, gravity, aeromagnetics, satellite imagery, magnetotellurics, heat flow, and electromagnetic sounding. Associated math/physics includes wave propagation, diffusion, forward and inverse scattering, genetic algorithms, fractals, tomography, rock physics, etc.

Before modern computers, most signal processing and analysis was single channel. Geophysicists tended to be electrical engineers steeped in time series analysis. Nowadays, a deeper understanding of the underlying physical process is required, and many practicing geophysicists have math-physics backgrounds. One needs to know geological process too, but this is easier to pick up than the math and physics.

The oil industry, emerging from a long depression, faces shortages of critical skills. There should be good opportunities for strong math/physics problem solvers over the next several years.

Note:

The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3:30 p.m. All students are welcome! Refreshments will be served.

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

Oklahoma State Physics Department

Seminars and Colloquia, February 17-21, 1997

Undergraduate Physics Journal Club:

Abstract:

New technological developments have put practical electric cars within reach, but politics may slow the shift away from internal-combustion engines.

(You may pick up the reading material in Rm. 145 of PSII)

SPS Invitational Physics Colloquium:

Abstract:

Nearby gaseous nebulae often appear very large in the sky -- sometimes the size of the full moon or larger. Despite this fact, the processes that shape nebulae often occur in much smaller areas generally not resolved in ground based images. Examples include the gas cooling and recombination zones behind shock fronts, gasdynamically unstable regions in supernova remnants and young stellar objects, plasma features in the relativistic wind from pulsars, and the interface between photoionized gas and molecular clouds in ionized regions.

The Hubble Space Telescope is capable of resolving many such structures in nearby nebulae. What from ground were indecipherable blurs giving only vague hints of insights just beyond our reach, become through the eyes of the HST cleanly resolved structures revealing the underlying physics at work in interstellar space. Just as the microscope revealed the workings of cells and thus changed our understanding of the human body, the Hubble Space Telescope is changing our view of the processes that shape interstellar gas.

In this talk I will discuss various recent results, ranging from HST observations of the blast wave in the Cygnus Loop supernova remnant to the dynamics of the synchrotron plasma at the heart of the Crab Nebula.

Note:

The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3:30 p.m. All students are welcome! Refreshments will be served.

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

Oklahoma State Physics Department

Seminars and Colloquia, February 24-28, 1997

Physics Colloquium:

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

Oklahoma State Physics Department

Seminars and Colloquia, March 3-7, 1997

Laser and Photonics Research Seminar:

Abstract:

Up until recently, there was no luminescent material that was both highly sensitive to radiation and, at the same time, suitable for stimulation with visible light. Anion-deficient aluminum oxide doped with carbon (Al2O3:C) is an extremely sensitive thermoluminescence (TL) material, with a sensitivity 50 times greater than the industry standard, TLD-100 (LiF:Mg,Ti). This new material is also well suited to Optically Stimulated Luminescence (OSL) applications due to a high cross-section for the laser light interaction with the traps and a high recombination efficiency. A novel Pulsed OSL (POSL) technology has been developed at Oklahoma State University. It utilizes the long life-time of the luminescent F centers from Al2O3:C, along with the possibility to stimulate the dosimeter efficiently with green Nd:YAG laser light, and to measure the luminescent emission in the blue. The presentation will discuss the physics of electronic processes in Al2O3, the approach to modification of luminescent properties of the material using crystal growth techniques and the advantages of the new POSL technique and automatic dosimetry system.

Coffee and cookies will be served at 3:45 p.m.

Oklahoma High Energy Physics Seminar:

Physics Colloquium:

Abstract:

Via TeraHertz (THz) time-domain spectroscopy (TDS) based on our unique opto-electronic THz beam system, we have experimentally addressed the nature of conductivity in doped silicon and have begun to understand molecular collisions through their effect on measured rotational lineshapes. I will describe definitive measurements of the complex conductivity from dc to 2.5 THz on doped silicon. These measurements do not agree with standard theoretical predictions, but do agree with a Cole-Davidson type distribution applied for the first time to semiconductors. Our observations on molecular vapors show that as the offset frequency from the rotational resonance is increased to as much as 200 linewidths or to more than 5 times the basic frequency, a transition occurs from the regime of van Vleck-Weisskopf theory to that of Lorentz. These measurements are well explained by a new molecular response theory, which explicitly includes the molecular orientation time during a collision.

Note:

The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3:30 p.m. All students are welcome! Refreshments will be served.

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

Oklahoma State Physics Department

Seminars and Colloquia, March 10-14, 1997

Spring Break

Oklahoma State Physics Department

Seminars and Colloquia, March 17-21, 1997

Week of APS March Meeting

Oklahoma High Energy Physics Seminar:

Physics Colloquium:

Note:

The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3:30 p.m. All students are welcome! Refreshments will be served.

Oklahoma State Physics Department

Seminars and Colloquia, March 24-28, 1997

Physics Colloquium:

Abstract:

A number of reasons account for the growing interest in optical techniques devoted to the investigation of biological tissue. Optical techniques employ non-ionizing radiation, they are non-invasive, they can provide continuous, real-time information, they are compatible with compact bedside instrumentation, and they are cost effective. The main difficulty with this approach results from the strong scattering of light in most tissues. I will discuss a frequency-domain technique developed in our laboratory, that is capable of performing quantitative spectroscopy in strongly scattering media. The quantitative measurement of the absorption coefficient has an important application in the determination of hemoglobin saturation and concentration in blood perfused tissues. The scattering coefficient may also provide valuable physiological information, for instance about blood glucose concentration. I will present results obtained on tissue-like phantoms, as well as on tissues in vivo. I will conclude by showing the first clinical results of frequency-domain optical mammography, which appears to be a potentially useful tool in breast cancer detection.

Note:

The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3:30 p.m. All students are welcome! Refreshments will be served.

Undergraduate Physics Journal Club:

Abstract:

Tornadoes, scourge of the Great Plains and where ever else they happen to appear, are being extensively studied using the latest technology. Though many features that lead to tornado formation have been observed, detection of these features does not necessarily foretell a tornado. We will discuss the observed mechanisms of tornado vortex formation as presented by Robert Davies-Jones of the National Severe Storms Laboratory.

(You may pick up the reading material in Rm. 145 of PSII)

Oklahoma High Energy Physics Seminar:

Physics Colloquium:

Abstract:

Light from solar radiation has been essential for all types of life since the very origin of the biosphere. Biological organisms from bacteria to humans have evolved many ways to use light. One class of them is energy transduction systems, which absorb light as energy sources. Another class is signal transduction systems, which detect light as signals to activate certain biological responses critical to survive and/or offering a way to probe their living environments. The photoreceptor is the first component in the signal relay chain for detecting photons and ultimately leading to a biological response such as visual excitation. We have been studying the physical principles which underlie receptor activation, using the photoactive yellow protein (PYP) as a model system. PYP is a water soluble photosensor for blue light found in Eubacteria. Absorption of blue photons, by its embedded chromophore (4-hydroxycinnamate anion), drives PYP into a cyclic chain of thermal processes: first to a short-lived red-shifted intermediate state, then to a long-lived blue-shifted state, and finally to the recovery of the original receptor state. For the first time, the Fourier transform infrared difference spectroscopic technique was utilized to detect and examine crucial changes in the structure and intramolecular interactions during the photocycle of PYP. Rich information was obtained that revealed chromophore photoisomerization, intramolecular proton transfer, and large conformational changes. This study has led to a molecular mechanism of photoreceptor activation in PYP and promoted the recognition of a general theme concerning photoreceptor activation in systems extending from bacteria to plants and the animal kingdom.

Note:

The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3:30 p.m. All students are welcome! Refreshments will be served.

Oklahoma State Physics Department

Seminars and Colloquia, March 31-April 4, 1997

Physics Colloquium:

Abstract:

Light is increasingly used for diagnostics and therapy in medicine and biology. This field, often referred to as Biomedical Optics, has shown great potential in such diverse areas as cancer diagnostics, retinal attachment, bone welding, functional imaging of brain activities, and Alzheimer detection. The basis for all these applications is a fundamental understanding of light propagation in cells, tissues, and organs of the human body.

During this colloquium I will present results from projects which address two unsolved problems in Biomedical Optics: (1) What features within a cell are responsible for the microscopic scattering properties of tissue, and (2) What theory does best describe the macroscopic light propagation in complex organs? To answer these questions we perform polarized light scattering experiments on biological cell suspensions and use transport and diffusion theory codes to predict the propagation of light in the human brain.

Note:

The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3:30 p.m. All students are welcome! Refreshments will be served.

Oklahoma High Energy Physics Seminar:

Physics Colloquium:

Abstract:

Materials research has played a very important role in the rapid evolution of medical imaging towards filmless systems. In mammography, the need for suitable solid state detectors for full breast digital imaging with high resolution has opened the door for further research in materials. Research is under way on a variety of solid state materials, both wide and small band gap type, that are being evaluated as image receptors for digital mammography. This talk will describe the present state of materials research and how the results may facilitate the development of new detection systems. The lecture will also address associated problems and possible future research directions.

Note:

The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3:30 p.m. All students are welcome! Refreshments will be served.

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

Oklahoma State Physics Department

Seminars and Colloquia, April 7-11, 1997

Oklahoma High Energy Physics Seminar:

Physics Colloquium:

Abstract:

A semiclassical approach for treating tunneling within classical trajectory simulations is described. Such an approach is practical for multidimensional systems where full quantum mechanical solutions are not feasible. The procedure can be easily implemented within standard classical trajectory simulations and thus allows for full-dimensional treatment of tunneling. The use of the method is illustrated with examples.

Note:

The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3:30 p.m. All students are welcome! Refreshments will be served.

Oklahoma State Physics Department

Seminars and Colloquia, April 14-18, 1997

Undergraduate Physics Journal Club:

Abstract:

Two dozen satellites hovering thousands of miles out in space are allowing people to locate themselves on the earth's surface with remarkable precision.

(You may pick up the reading material in Rm. 145 of PSII)

Oklahoma High Energy Physics Seminar:

SPS Invitational Physics Colloquium:

Abstract:

Going from the graduate school environment to the arena of corporate America is a significant milestone in a person's career. It could involve major changes in many aspects of life. This presentation aims to:

1. highlight some of the issues in this transition process, e.g.
2. raise the awareness of those issues, and
3. stimulate discussions on them.

The issues of concern are perspectives, attitudes, expectations, etc. Some suggestions on how to make a smooth transition will be discussed. The format of this presentation will be more of an interactive forum than the typical technical seminar.

Dr. Chan is the guest of the Society of Physics Students.

Note:

The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3:30 p.m. All students are welcome! Refreshments will be served.

Oklahoma State Physics Department

Seminars and Colloquia, April 21-25, 1997

Undergraduate Physics Journal Club:

Abstract:

On the role that my physics background has played in my career as a telecommunications engineer at Wil-Tel.

(Graduate students are welcome to attend.)

Oklahoma High Energy Physics Seminar:

Physics Colloquium:

Abstract:

One of the primary scientific missions of the Hubble Space Telescope is to determine how galaxies form. This was the motivation for the Hubble Deep Field project, the results of which will be reviewed. A different approach is to study newly forming dwarf galaxies that are nearby. I will report on HST observations of the most chemically young galaxy known, I Zwicky 18, which we believe may be a candidate for a "new" galaxy forming in our galactic "backyard". HST images show unparalled detail about this dwarf galaxy, including resolution into stars for the first time. Analysis of the data indicate that it is indeed a new galaxy forming from intergalactic hydrogen clouds. But the images also reveal the presence of an older companion galaxy which may have influenced both I Zw 18's formation and chemical evolution.

Note:

The traditional student-speaker chat will begin in Physical Sciences Room 147 at 3:30 p.m. All students are welcome! Refreshments will be served.

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

Oklahoma State Physics Department

Seminars and Colloquia, April 28-May 2, 1997

Prefinals Week

Oklahoma High Energy Physics Seminar:

Oklahoma State Physics Department

Seminars and Colloquia, May 5-9, 1997

Finals Week

Laser and Photonics Research Colloquium:

Abstract:

In this talk we will discuss two recent experiments in which the temporal resolution capabilities inherent in femtosecond lasers are adapted for high speed electrical measurements. In the first experiment, electric field induced optical second harmonic generation is demonstrated as a probe for the measurements of ultrafast electrical pulses in silicon devices. This noninvasive technique offers subpicosecond temporal resolution and vector field measurements capabilities. In the second experiment, picosecond laser pulses are delivered via fiber to a metal-semiconductor-metal (MSM) photodiode integrated on a rapid single flux quantum (RSFQ) device to generate fast electrical pulses. A cascade optical splitter/recombiner configuration permits selection of bit pattern and clock rate from 80.6 MHz to 20.6 GHz. This optoelectronic clocking technique has been applied to demonstrate triggering of an RSFQ flip-flop at 1.3 GHz and to demonstrate triggering of a Josephson transmission line up to 20.6 GHz.

Coffee and cookies will be served at 3:15 p.m.

Oklahoma State Physics Department

Seminars and Colloquia, May 12-16, 1997

Laser and Photonics Research Colloquium:

Abstract:

Depositing metals using Chemical Vapor Deposition is a well developed technique in industry. It is used to coat thin layers of metal over a surface that can be raised to a specified temperature. Patterning of the metal can take place using the same photolithographic techniques used in the semiconductor business. Industry and the government has the desire to eliminate the photolithographic process and move to a direct write process. Laser Chemical Vapor Deposition (LCVD) has been recognized as a possible technique for the direct write process. We have done some preliminary studies and tests which lead us to believe this is viable approach to the direct write technique. We will discuss the procedure, results, definitive applications and extend it to possible applications as well.

Coffee and cookies will be served at 2:45 p.m.

Last Updated: 9 May, 1997.

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