Department of Physics
SCHEDULED EVENTS (1999-2000)
OTHER IMPORTANT DATES
Vibrational Sum Frequency Spectroscopic (VSFS) Study of
Biological Surfactant Ordering
Cindy A. Regal, '01, Summer Research
Assistant, University of Oregon, Eugene, OR.
Ms. Regal will discuss VSFS, a new technique being developed by chemists who have reached into the physicists' realm of non-linear optics to devise a novel surface selective spectroscopic technique capable of providing ordering information about surfactant molecules in biological membranes.
Molecular Outflow in Orion KL Nebula
Paul T. Kondratko, '00,
Summer Research Assistant, MIT Haystack Observatory, Westford, MA
Mr. Kondratko will discuss three maser emission lines emanating from the Orion KL nebula as detected by the MIT Haystack Very Long Baseline Interferometer. The sources of these three emission lines are not cospatial. Hence, Mr. Kondratko will discuss inferences that one might draw from these spectral lines, including small gradients in temperature, density, and SiO abundance.
Liquid Crystal Structural Analysis Using X-rays
Joshua Cross, '01, Summer Research Assistant, Department of Physics,
Lawrence University
Spatial ordering in liquid crystals can be measured using an x-ray area detector and reciprocal-space lattice mapping. These measurements are performed by fitting a Gaussian to the x-ray/liquid crystal data and then convolving the result with a Lorentzian, the anticipated shape of the structure factor. (This talk will be a preview of the talk that Mr. Cross will deliver at the Pew Midstates Science Colloquium at the University of Chicago during the weekend of Nov 5-7.)
Town Meeting of the Entire Physics Department
Following Mr. Cross's talk, we will hold a departmental town meeting, whose purpose is to discuss various matters of concern to students and faculty, e.g., colloquia, GRE, SPS, WOP, APS, LPW, Bjorklunden, letters of recommendation, the Senior Capstone program, ... All physics majors are expected to attend this meeting.
Confinement of an Electron Plasma in a Toroidal Magnetic
Field
Angela Jean Kopp, '01, Summer Research Assistant, Department of Physics,
Lawrence University
Ms. Kopp will discuss the results of diagnostic and preliminary trapping experiments conducted recently on non-neutral plasmas in a partially toroidal confinement region. Progress towards a more sophisticated design will be discussed in the context of an equilibrium/stability analysis. (Ms.Kopp will be presenting this same material in a poster at the upcoming Seattle meeting of the Division of Plasma Physics of the American Physical Society.)
Coherent Population Trapping
Jessica Reeves, '00, Department of Physics, Lawrence University
Ms. Reeves will describe the exciting phonomenon of coherent population trapping wherein she compels atoms to nap in broad laser light. This talk will summarize work done in a Capstone Project carried out during the fall term.)
This first colloquium of the winter term describes the use of optical techniques to produce strongly polarized gases. These hyperpolarized gases have been used to produce high-resolution images of lungs.
Th 20 Jan: 3:30 PM Y-88: Special departmental tea.
Th 20 Jan: Y-161, 4:00 PM Refreshments; 4:15 PM Science Colloquium
Laser Cooling
Dr. Thad Walker, Department of Physics, University of Wisconsin,
Madison
Most commercial applications of lasers use laser beams to heat materials. By exploiting quantum mechanical effects, lasers can also be used to cool collections of atoms to extremely low temperatures. Professor Walker will look at applications of this technique.
Satellite data are an important component of weather analysis. Nearly all weather discussions seen on television show a sequence of satellite images. Identification of clouds is not as simple as the television may indicate. This presentation will discuss the physics behind weather satellite observations.
Flown onboard satellites are instruments that measure electromagnetic energy that is either reflected or emitted by our planet. These instruments are called radiometers. Two common types of radiometers are used in observing weather from satellites. One type measures the amount of visible light from the sun reflected back to space by the Earth's surface or by clouds. The second measures the amount of radiation emitted by these entities. The satellite images you see on TV weather channels are examples of the later.
In addition to covering weather analysis, examples will be presented on how weather satellites are used in Fire Detection, Snow Cover, Vegetation Monitoring, Sea Surface Temperature Analysis, Monitoring Plumes from Volcanic Eruptions, Urban Heat Islands, and Climate Change Monitoring.
Th 3 Feb 4:15 PM Y-161: Science Hall Colloquium
Is this Wisconsin Winter Warmth Global Warming?
Dr. Steven Ackerman, Department of Atmospheric Sciences,
University of Wisconsin, Madison
The last few winters in Wisconsin have been relatively warm, at least compared to the last 100 years. News articles often suggest that this is because of global warming. Is it? Well maybe. The difficulties behind answering this question confidently will be addressed in this presentation. An overview of the current evidence for global warming will first be presented. Demonstrations will then be performed that highlight the complexities underlying this apparently innocent question.
Tu 29 Feb: 11:45 AM Y-90 Physics Colloquium
Silicon Micromachines for Science and Technology
Dr. David Bishop, Bell Labs Innovations, Lucent Technologies
The age of Silicon Micromechanics is upon us. Silicon Micromachines are devices, smaller than a human hair, which, like macromachines, can move to accomplish a variety of tasks. Micromachines have now been built which can do almost everything their full-sized counterparts can. These include things like rotary electric motors, toothed gears, linear stepper drives, hinges, inclined planes, screws, pulleys, tweezers, wheels, bending beams, plates and numerous other devices. Technologists are interested because these devices are small, cheap, robust, easy to make using the techniques developed to build integrated circuits and can be integrated with digital and analog electronics. In my talk, I will first introduce the technology, describe how one builds a Micromachine and then show many examples of such devices in operation. The Age of Micromechanics is likely to revolutionize the world, as has the age of Microelectronics. In this presentation, we will endeavor to show how this extraordinary new technology has the potential to change the world we live in.
The Dark Matter Problem
Dr. Michael Turner, American Astronomical Society Harlow Shapley
Memorial Lecturer. Dr. Turner is a particle physicist and cosmologist.
He is a member of the physics faculty at the University of Chicago
and on the staff of the Fermi National Accelerator Laboratory.
Electrons in Circular Orbits: Exploring a New World of
Atomic and Molecular Structure
Dr. Steve Lundeen, Department of Physics, Colorado State University.
Dr. Lundeen is an atomic physicist who, prior to joining the faculty at
Colorado State, served on the faculties at Harvard
and Notre Dame.
All atoms and molecules have excited states where one electron is bound in a nearly circular orbit to the remaining positive ion. To a large extent, however, these states are unexplored, since they are nearly invisible to standard methods of spectroscopy. Dr. Lundeen will describe new methods which allow close study of these unusual states, and show what can be learned from them.
Fr 21 Apr 4:10 PM PM Y-90 Physics Colloquium
High-L Rydberg Ions: The Territory for the RESIS/Microwave Method
Dr. Steve Lundeen
Recent work has demonstrated that the Resonant Excitation Stark Ionization Spectroscopy (RESIS) method, which has proved so powerful in studies of neutral Rydberg states, can also be used to study high-L Rydberg states of ions. Dr. Lundeen will describe these initial studies, and indicate some possible future directions.
Self-Organization in Nature
Dr. David Newman, Department of Physics, University of Alaska--Fairbanks
In nature there are many systems which appear to exhibit some form of self-organization. Among these are forest fires, earthquakes, sandpiles, turbulent transport and even many aspects of society itself. Investigations into the similarity of the dynamics of such systems have been undertaken by using simple cellular automata models. Recently, a Self-Organized Criticality (SOC) model for turbulent transport in magnetically confined plasmas was proposed in order to explain some of the observed features of the transport dynamics in these plasmas. These models have produced a remarkable amount of insight into the dynamics of such systems. Some of the basic features of SOC systems, from forest fires to earthquakes and sandpiles will be discussed. Then, a perturbed extension of a sandpile model of turbulent transport will used to investigate methods for possible control of SOC systems. Finally, time permitting, some speculation on the implications to society of attempting to control certain behavior (for example, risk avoidance) in the context of an SOC system will be discussed.
Tu 16 May 11:10 AM Y-90 Physics Colloquium
Shear Flow Meets the World
Dr. David Newman