Department of Physics
SCHEDULED EVENTS (2002-03)
OTHER IMPORTANT DATES
3:00 PM Y-104: Visit to Physics Department Tea.
4:00 PM NS-202: Informational Session
Lawrence is affiliated with the Biosphere program. Further, this fall term Liz Kruesi, LU '04, is studing in the program.
Note that the morning part of the GRE examination is no longer given in paper format. It is available only at computer sites, the nearest two of which for Lawrence are in Oshkosh and Stevens Point. The examinations are administered at almost all times on a first-come first-served basis. If you are planning to take this examination this fall, you must register to reserve a time. October is a good month to take the general examination so that, come December (see later item), you can focus on the subject area examination, which is given as a paper and pencil examination. Further information about the GRE can be found at http://www.gre.org.
Town Meeting of the Entire Physics Department
The purpose of this meeting 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.
1:15--3:00 PM: Time for individual appointments. Sophomores and juniors thinking seriously about engineering as an option should make an appointment to talk with Mr. Groszewski. Sign up on a list next to Prof. Cook's office door, Y-107.
3:00--3:30 PM: Mr. Groszewski will attend the physics department tea in Y-104.
3:30--4:15 PM, Y-115: Mr. Groszewski will make a short presentation and then respond to questions about engineering in general and about Washington University in particular.
Breakfast with students at Lucinda's -- Sign up with Professor Stoneking
Tour of department
Meetings with faculty and students
Lunch with students at Lucinda's -- Sign up with Professor Stoneking
Meetings with faculty and students
3:30 PM Y-104: Department Tea (note time slightly later than usual)
4:15 PM Science Hall 202 Physics Colloquium: Experiments with Dusty Plasmas on the Ground and in Space
Micromagnetics of Magnetic Recording Media
The bit density of magnetic recording media currently doubles annually. Continuing to advance at this rate poses significant technological problems, but even more importantly physical questions. The two most important limitations in the recording industry are size and speed, two aspects of which new measurement techniques on objects with nanometer dimensions are particularly well suited to study. A brief history of magnetic recording and some discussion of the recent advances in recording techniques will be given, paying particular interest to the areas where the physical limitations are of the most importance. I will present a joint experimental and computational study of nanometer scale nickel islands, showing how the infromation obtained from this study impacts the dynamics of magnetization reversal.
Michelle L. Milne, LU '04 and Scott J. Kaminski, LU '04
Calculations of Magnetic Fields Produced by Square
Helmholtz-like Coils
Kimberly A. Robinson, LU '03
Simulation of Hydrodynamic and Magnetodynamic Rising
Bubbles
Christopher Phelps, LU '03
Charged Particle Tracking in the Cyclotron at Michigan State
University
Ryan Peterson, LU '03
Imaging Electron Plasma in a Partially Toroidal Trap
Joseph E. Wells, LU '03
Populational Dynamics in a Chopped HeNe Laser
Robert Hanisch, LU '76, NASA Space Telescope Institute
A Visit to a Virtual Observatory
Th 23 Jan 7:30 PM Y-121: Science Hall Colloquium Scientific Searches for intelligent Life in the Galaxy.
Recent discoveries of planets around other stars are fueling several ongoing and planned searches for signs of intelligent life beyond our own solar system. We'll review past searches and look at new techniques that may reveal the presence of extraterrestrial civilizations.
Fr 24 Jan 11:10 PM Y-115: Physics Colloquium White Dwarf Stars: The Far Future History of our Sun.
Following exhaustion of its internal hydrogen fuel in about 4 billion years, our Sun will follow the path of countless stars before it, and eventually become an extremely compact, cooling, crystalline stellar remnant. Along the way, it will undergo several fascinating transformations. In this talk, Professor Kawaler will review the late evolution of solar-type stars, and illustrate how we probe such objects using the new science of asteroseismology.
The following two talks are scheduled. There will also be opportunity for students to join Professor Turner for lunch when he is here and for students to arrange individual or small group conversations with him. Arrangements for those components of the visit should be made with Professor Collett.
Tu 4 Feb 11:10 AM NSB-102: Physics Colloquium Inflationary Cosmology
Tu 4 Feb 7:30 PM Y-121: Science Hall Colloquium The Dark Side of the Universe.
In this talk, Professor Turner will talk about exotic forms of matter that may exist and how that invisible (dark) matter may be responsible for the acceleration of the rate of expansion of the universe. Following the lecture, there will be a brief reception in the lobby of Youngchild Hall.
Copies of Professor Turner's recent article on dark matter are on the tables in Y-104 and the CPL. You might find reading the article before Professor Turner arrives will make for a more productive interaction with him.
Suzanne Witt, LU '03
Point spread function deconvolution in 3D micro-CT angiography
for multi-scale vascular tree separation
Micro-CT angiography of small laboratory mammal organs visualizes vascular branches on a large range of scales, ranging from root-level branches (mm) to endarteriolar vessels (10-40 micro-meters). Multi-scale vascular tree separation is facilitated by the ability to set a single gray-scale threshold value for vessels of all generation levels. Due to the non-ideal modulation transfer function (MTF) of the imaging system, object contrast varies significantly with scale, and the definition of a gray-scale threshold for vessel segmentation becomes a problem. From computing the MTF of the imaging system, we see that the signal-to-noise ratio remains acceptable even at higher resolutions. The increase in noise from performing a point spread function (PSF) deconvolution will not have a significant effect on the overall signal-to-noise ratio of the images and that, to improve the gray-scale contrast, performing a PSF deconvolutiion is appropriate. We find that performing a PSF deconvolution on the micro-CT projection images reduces the thresholding problem.
Elizabeth Kruesi, LU '04
Detection of Cosmic Ray Generated Electrons by Electromagnetic
Calorimetry
Calibration and use of an electromagnetic calorimeter will be discussed. This calorimeter was used during the summer to detect muons and electrons at the surface of the earth. First, event plots were made and, finally, the energies of the detected electrons were plotted. The calorimeter that has been in use this summer at the Laboratory for Astrophysics and Space Research (LASR) at the University of Chicago was previously used in a high-altitude balloon flight; the name of that flight is the High-Energy Anti-Matter Telescope (HEAT). This same calorimeter will be used in the future to calibrate a calorimeter for another high-altitude balloon flight. Pretty pictures will be presented.
Megan Schendel, LU '04
Characterization of Alumina-Glycerol Slurries
Particle slurries are used in the creation of ceramics. These ceramics have found applications in areas such as telecommunications, high-temperature superconductors and insulators due to their widely varying mechanical, optical, thermal, and electrical properties. The physical properties and usefulness of a ceramic material depend on the materials used as well as particle size, uniformity, and growth processes. This talk will cover some of the techniques used to characterize some of these properties necessary for a future generation of high quality ceramics.
David Munro, Lawrence Livermore National Laboratories
Progress at the National Ignition Facility
The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory is a high power, nanosecond pulse glass laser. Light from the first four beams has recently reached target chamger center. The complete facility will have 192 beams capable of producing a total of 1.8~MJ of 351~nm light at 500~TW. This talk will describe the construction of the facility, its current state, and the schedule for completion. Physcis experiments will begin this summer and be conducted in parallel with continuing construction.
Jack Schendel, Sandia National Laboratories
An Interesting Russian Observation on Ignition
Criterion for Pure Fusion
This talk introduces the basic notions of nuclear fission and fusion energy production and approaches for pure fusion. A Russian variant of the Lawson criterion for fusion ignition and novel approaches that may actually achieve ignition are also presented.
Tu 8 Apr 4:15 PM NSB 102: Physics Colloquium
Communicating at Light Speed
Optical fiber networks carry an enormous amount of information around the world, including phone calls, emails, and internet downloads. Dr. Gilbert will describe how all that stuff manages to travel in tiny strands of glass fiber; she will highlight some of the important advances in science and technology that have made this possible.
We 9 Apr 8:30 AM Y-115: Physics Breakfast/Seminar
Applying Physics to Optical Fiber Communications
The optical fiber communications industry is constantly seeking new optical technology to increase the amount of information that can be transmitted in these systems. This has raised a number of challenges that require research in physics and engineering. Dr. Gilbert will describe research and developments carried out by her group at NIST.
Please see Dr. Brandenberger to make arrangements to have a meal with Dr. Baer or to talk with him individually or in small groups during his time here.
Fr 11 Apr 3:00 PM NSB 102: Joint Physics/Biology Colloquium
Insights into the molecular basis of cancer and developmental biology through Microgenomics
The new field of Microgenomics provides the technology to study the molecular makeup of very small populations of cells extracted from biological specimens. Laser-based microdissection instruments and linear nucleic acid amplification allow quantification of the RNA and DNA contents of pure cell populations captured from biopsies---thereby allowing precise measurements in microscopic samples as small as a single cell and providing insight into which combinations of the tens of thousands of known genes are involved in the transformation of normal cells to tumor cells as well as which genes are involved in the first stages of human embryo development. Dr. Baer will discuss the development of new cancer diagnostics and experiments studying the very early stages of human embryo development.
Th 24 Apr 11:10 AM Y-115: Physics Colloquium
Bigger is NOT Always Better: The Motivation for Nanostructured Magnetic Materials
In Michael Crichton's recent novel, Prey, the role of villain is filled by `nano-bots'---nanometer-sized robots created by scientists. These nano-bots, designed to help humans, ultimately turn on their creators. `Nano' is the hot phrase of the decade; the federal government has established a comprehensive program targeting nanotechnology research.
Why are nanomaterials so interesting? Answer: Nanostructuerd materials find applications in everything from coatings to hard disks to cosmetics. Furthermore, the nanoscale is a unique length scale in materials, since nano is intermediate between atoms and bulk materials, and about the size of biological molecules. Nanomaterials are a converging point for different scientific disciplines, thus opening the door to exciting new discoveries. Two examples highlight the study of magnetic nanostructures. The first is that nanostructured materials allow us to study fundamental questions about disordered magnetic systems. Most magnetic interaction lengths are on the scale of tens of nanometers. Nanostructured materials thus are inhomogeneous on the same length scale as these characteristic interaction distances, which produces significant changes in fundamental magnetic properties. A second example is the use of magnetic nanoparticles in biological applications, including magnetic imaging and cancer treatment, where part of the emphasis lies on the need for interdisciplinary effort that requires scientists to draw upon various disciplines.
Th 24 Apr 7:30 PM Y-115: Physics Colloquium
Nanomagnetism from A to C: Understanding the Transition between Crystalline and Amorphous Magnetism
How magnetic properties are affected by nanostructures raises some very interesting questions in magnetism. The answers to these questions have implications ranging from magnetic phase transitions to improving materials for information storage and medical applications. Nanostructured materials in which small crystallites serve as building blocks offer significantly greater opportunities for understanding magnetism in complex systems.
Most properties of nanostructures are highly dependent on grain size, but magnetic properties are dependent on the magnetic grain size. The primary mechanism for enhancing magnetism in materials is the introduction of disorder in the grain boundaries. This disorder can impede domain-wall motion or decrease magnetic interactions between grains. GdAl2 is a model system for examining ferromagnet-spin glass crossovers. Crystalline GdAl2 is a ferromagnet with a Curie temperature of 165 K, while amorphous GdAl2 shows spin-glass-like behavior with a freezing temperature of 16 K. Nanostructured GdAl2 shows spin-glass-like behavior and ferromagnetic behavior; however, the Curie temperature is significantly depressed, and the freezing temperature occurs at 60 K, which is much higher than the amorphous freezing temperature. Our recent work demonstrates that the transition from ferromagnetic to spin-glass-like behavior cannot be explained by size effects: one must also consider the effects of chemical disorder. The results of these studies have implications for our understanding of phase transitions in magnetically inhomogeneous materials.
Ryan Peterson, LU '03
CTIO REU: El Burro Sabe Mas Que Tu! (Cerro Tololo Interamerican
Observatory Research Experience for Undergraduates: The donkey knows
more than you
Over Term II of this year, I spent 10 weeks in Chile modeling planetary nebulae as part of an REU program. Situated near La Serena, Chile, Cerro Tololo Interamerican Observatory (CTIO) is the central observatory for American research in the southern hemisphere. This talk will discuss the REU application process, my Chilean living experiences, and my research.
Photo Shoot: 4:00 PM on the lawn at 228 North Park. Faculty members, seniors and juniors leaving for engineering schools should meet on the steps for the taking of this traditional photo.
Suzanne Witt, LU '03
Imaging a Self-Assembling Crystal Using Scanning Tunneling
Microscopy
You'll see the results of an investigation into the atomic imaging capabilities of scanning tunneling microscopy using a sample of highly oriented pyrolytic graphite and its ability to image the self assembly properties of an organiz fatty acid in real time.
Mark Growdon, LU '03
Dynamics of a Toroidal Electron Plasma
Annual Reception for physics graduates and their graduation guests.