Department of Physics
SCHEDULED EVENTS (2003-04)
OTHER IMPORTANT DATES
Dr. Jennifer Herek. LU '90, Group Leader. FOM Institute for Atomic and Molecular Physics, Amsterdam, The Netherlands
Quantum Control, Interferring Pathways, and Light Harvesting
Dr. Herek is establishing a new research program and femtosecond laboratory at AMOLF, where she directs investigations of the dynamics of photosynthesis in biologically important molecules. Dr. Herek's strategy for applying femtosecond spectroscopy to these targets includes quantum control, which is a feedback-driven, coherent excitation process that exploits genetic algorithms to maximize molecular change along multiply constructive pathways. Dr. Herek is a dynamic speaker who will explain her work in ways that everyone can understand.
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.
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.
Mr. Paul Groszewski, Dual Degree Program representative from Washington University, St. Louis, MO, will be on campus to discuss Lawrence's affiliation with Washington University in a program that makes engineering available to Lawrence students.
Paul J. Schonfeld, LU '05
Remote Sensing and Numerical Modeling of Volcanic Ash Plumes in
Alaska
In reporting on his research activities in the Solid Earth Geophysics Program based at the Geophysical Institute in Fairbanks, Alaska, Mr. Schonfeld will explain how he employed remote sensing and the numerical dispersion model to track the ash cloud produced by the eruption of Mt. Spurr in Alaska on 17 September 1992.
Michelle L. Milne, LU '04
Using Feedback to Extend Confinement in the Lawrence Nonneutral
Torus
Reporting on her research efforts in Professor Stoneking's plasma research program last summer, Ms. Milne will explain how the application of feedback potentials inside the Lawrence Nonneutral Torus successfully extended the confinement time of electron plasmas by more than an order of magnitude.
Jason Levin-Koopman, LU '04
Monte Carlo Simulations on Magnetic Nanocontacts
Mr. Levin-Koopman will report on his collaboration with Professor Andrew Kunz on the spin-dependent conductance of nickel nanocontacts (nine atom bridges) that electrically connect large magnetized nickel electrodes. The conductance of these nanocontacts depends strongly on the direction of magnetization of both the junction and the electrodes. Mr. Levin-Koopman's simulation, which utilizes the Monte Carlo relaxation technique, yields the magnetization and hence the conductance.
Matthew Stackpole, LU '05
Does Size Really Matter? Why I Eschew Diffraction but Love
Scanning Tunneling Microscopy
Mr. Stackpole will report on his work with Professor Jeffrey Collett in the area of surface physics and nanoscience. This talk will begin with an introductory presentation on scanning tunneling microscopy after which Mr. Stackpole will discuss the quantum mechanical view of tunneling and how tunneling enables imaging on the atomic scale.
Matthew Dietrich, LU '04
Computational Modeling of Mach Cones in Coulomb Crystals
Mr. Dietrich will report on work performed at Baylor University last summer concerning complex ("dusty") plasmas. Using software originally developed to study the behavior of asteriods, Mr. Dietrich investigated the generation of shock waves in crystals composed of macroscopic dust particles. Several modes that correspond closely to experiment were found, but at least one experomental mode has yet to be identified computationally.
Lauren Kost, LU '05
The Electrostatic Potential of Electron Mirrors
Ms Kost will report on her recent work with Professor David Cook in which she employed finite element techniques to produce two- and three-dimensional plots of the electrostatic potential inside the Lawrence Nonneutral Torua (LNT). Ms Kost will discuss the finite element method for solving partial differential equations and how this method can be used to find the potential inside the LNT. The results reveal that contributions to the potential arising from trapping grids inside the torus are surprisingly small.
Megan Schendel, LU '04
Fiber Bragg Grating Refractive Index Modulation Amplitude Axial Profile
Measurement
A fiber Bragg grating is one of the most important fiber optic devices in use today, particularly for its use as a wavelength divider or dispersion compensator. They are also valuable as strain and temperature sensors in diverse applications such as transportation, medical sensing, and satellites. The axial profile of a fiber Bragg grating's refractive index modulation can be used to evaluate properties of the grating and is useful as feedback on the grating creation process. There is no instrument on the market designed to make this measurement. A local automated system for this measurement was developed at the NIST Boulder site. The results of several measurements, as well as system specifications, automation, and attributes (such as resolution) will be discussed.
Nicholas Mauro, LU '05
Hexatic Liquid Crystal Phases and Exploring the
Tricritical Phenomenon
A theoretical outline is presented which examines the effect of critical behavior on the XY universality class order parameters. The breakdown of mean field theory near the phase transition between smectic-C (SmC) and smectic-I (SmI) phases of TB10A, 8OSI and C10 is examined and critical exponents, order parameters and the structure factor are developed quantitatively to explain scattering effects in liquid crystal thin films. Experimental results from x-ray diffraction studies of TB10A and C10 hexatic phases motivate further study of tricritical points in liquid crystal mixtures.
Steven Hahn, LU '05
Time of Flight Study of Antimony Borate Glasses
Antimony borates form a relatively high-density glass, making them good candidates for detectors and other industrial applications. A laser photo-ionization time of flight mass spectrometer was used to investigate the intermediate range structure of antimony borate glasses over a large compositional range. The goal was to see if our findings were consistent with studies of the local range order conducted using other techniques such as NMR. Also conducted were efforts to increase the consistency of the spectra of glasses with low antimony content, including, optical absorption measurements, doping the sample with lead, and using a Nd: YAG laser. Lastly, we will compare our findings with similar lead and bismuth borate systems previously studied at Coe College, where this work was done during the previous summer.
Dwight Mills, LU '04
Raman Laser Spectroscopy using Methylene Chloride
We investigated the Raman Effect, first discovered in 1928, by use of a tetrahedral molecule. The Raman Effect involves the annihilation of an incident photon and the creation of a scattered photon with a slightly different frequency because of a small transfer of energy to a molecule in a transparent medium. Stokes and anti-Stokes features corresponding to different vibrational modes of the methylene chloride molecules were analyzed. This experiment was carried out in the summer of 2003 at Lawrence University with Professor John Brandenberger.
Professor Paul Bunson, Lawrence University Department of Physics
The Mathematics of Juggling: A Lecture Demonstration
Dr. Feller, who is visiting to promote the REU program at Coe College, will be arriving in the early afternoon on Thursday 26 Feb and will be available to talk with students individually about that program on Thursday afternoon and for much of the day on Friday. Interested students should make appointments with Dr. Kunz, who is organizing the visit.
Th 26 Feb: 3:30 PM (Delayed) Departmental Tea, Y-104
Th 26 Feb: 4:15 PM Y-115: Physics Colloquium
Dr. Steve Feller, Coe College
Adventures with Glass at Coe College: a Focus on Borates
In this talk, Dr. Feller will look at a few selected aspects of current research with students on glass with a focus on borate and borosilicate glasses. These aspects include
Student projects that lead to publication will be discussed to give you an idea of what REU students may contribute if they join us for a summer of research.
Mo 5 Apr 4:00 PM: Science Hall Colloquium:
Fundamental Particles, Fundamental Questions
Particle physics seeks to answer the questions: What is our physical universe composed of? In what distinct ways do the smallest particles of matter interact with one another? This talk introduces our current understanding of these issues, indicates where some profound mysteries remain unplumbed, and discusses how experiments in the upcoming decade will help advance our knowledge.
Tu 6 Apr 11:10 AM Y-115: Physics Colloquium:
Why is this quark different from all other quarks?
One of the great unanswered questions in high-energy physics is how the masses of the fundamental particles arise. The origin of the top quark mass is particularly puzzling since the top quark is so much heavier than the other elementary fermions. I will discuss how the heavy top quark makes a difference in our efforts to understand how mass is generated and in what sense the top quark might therefore be different from its `cousins' the up and charm quarks.
Elizabeth Kruesi, LU '04
Telescope to Study the Cosmic Infrared Background
The future high-altitude balloon-borne telescope project, ``the Explorer of Diffuse Galaxy Emission (EDGE)'', will be discussed. (Emphasis will be placed on the construction, analysis, and use of particular electronic components of EDGE.) This telescope will look at the temperature fluctuations in the Cosmic Infrared Background (CIB). By studying these fluctuations, we can observe the `structural clumpiness' of the early universe.
Megan Schendel, LU '04
Nano-alumina Particle Slurries
Standard alumina slurries (pre-ceramic liquid) contain particles with diameters on the order of 100nm, along with dispersant molecules to keep them from clumping. Introducing nano-scale particle (~20nm diameter) changes system properties dramatically and could potentially offer substantial improvement on the finished ceramics. The present study investigates the deviation of these nano-particle slurries from conventional ceramic theories. Important ceramic properties such as solids loading, elastic moduli, and shear rate are seen to vary with the size of the dispersion molecules.
Th 13 May Time 8:00 PM Youngchild 121: Science Hall Colloquium:
Giant Telescopes, Heavy Metal, and Ancient Superstars
Old stars in the Milky Way Galaxy record the history of creation in our part of the Universe stretching back almost to the beginning of time. Giant new telescopes using space-age technology have given us a glimpse of the first stars, and from the compositions of stars that formed more than 10 billion years ago, we can trace the origin of the first elements fused from primordial hydrogen and helium, and identify sites of nucleosynthesis. Our own Solar System is made from the debris of both ancient and modern supernovae. The elements of the periodic table allow us to explore our own origins in the Milky Way.
Fr 14 May Time 4:10 PM Youngchild 115 Physics Colloquium:
Heavy Elements in the Young Milky Way
The compositions of progressively more and more metal-deficient stars allow us to reconstruct the synthesis of the elements in the Milky Way galaxy from the first stars to the present generation. The origin of heavy metals at the earliest times in the history of the Galaxy is uncertain, but production of elements such as Sr, Y, and Zr dominated. Heavier neutron capture elements, including the lanthanide elements, became more abundant only after the Galaxy reached a metallicity of 10-3 time solar, and rapid neutron capture processes in Type II supernovae from 8-10 solar mass stars began to contribute. Until a metallicity of 10-2 solar, the abundance pattern of the heavy (Z>56) n-capture elements in most old stars is well-matched to a dominant rapid neutron capture nucleosynthesis pattern, rather than the traditional mix of rapid and slow neutron capture processes that is observed in the Solar System. The appearance of slow neutron capture elements as metallicity increases reflects the longer stellar evolutionary timescale of the low-mass stars in which the slow neutron capture process operates. The abundances of the heavy metals in these metal poor stars show clear evidence for a large star-to-star dispersion in the heavy element-to-iron ratios. This condition may have arisen from individual nucleosynthetic events in rapidly evolving halo progenitors that injected newly manufactured neutron-capture elements into an inhomogeneous early Galactic halo interstellar medium.
Photo Shoot: 4:15 PM (promptly) on the steps on the west side of Downer Commons. Faculty members, seniors and juniors leaving for engineering schools should meet on the steps for the taking of this traditional photo.
Annual Reception for physics graduates and their graduation guests.