Department of Physics
SCHEDULED EVENTS (2009-10)
OTHER IMPORTANT DATES
Note that what used to be the morning part of the GRE examination (the general part) 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, later in the term (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.
Dr. Baer, a major contributor to laser physics and various applications thereof, will discuss the 50-year history and impact of the laser first demonstrated by Theodore Maiman of Hughes Aircraft in 1960. Dr. Baer is one of Lawrences most accomplished physics graduates. Prior to joining Stanford, he was founder of Arcturus Bioscience, Inc. In 1996, where he served as the company's Chairman and CEO until 2005. Prior to Arcturus, Dr. Baer was Vice President of Research at Biometric Imaging, where he led an interdisciplinary group developing applications in the areas of AIDS monitoring, bone marrow transplant therapy, and blood supply quality control. From 1981-1992, Dr. Baer was at Spectra-Physics, Inc., where he held positions as a Research Scientist, Spectra-Physics Fellow, and Vice-President of Research. In 1989 he co-founded a new company, Spectra-Physics Laser Diode Systems, which was established to commercialize diode and solid-state laser instruments. Dr. Baer has been a pioneer in many areas of biotechnology, laser development, and laser applications, and is listed as an inventor on over 60 patents. He graduated with a B.A. in physics from Lawrence, magna cum laude, and received his M.S. and Ph.D. in atomic physics from the University of Chicago. He is a fellow in several international scientific societies.
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., key card access to departmental spaces, machine shop and laboratory policies, summer research programs, physics colloquia, GRE, SPS, WOP, APS, LPW, Bjorklunden, letters of recommendation, the Senior Capstone program, ... All physics majors are expected to attend this meeting.
Rob Niederriter, LU '10
Fluctuations and Transport in the Enormous Toroidal Plasma Device at UCLA
Turbulence and transport across magnetic field lines disrupt plasma confinement, which is particularly troublesome in toroidal geometries potentially useful for fusion energy. We investigate fluctuations of a helium plasma in the Enormous Toroidal Plasma Device (ETPD) at UCLA using 4-tip Langmuir probes to measure potential and ion saturation current. ETPD is a simply magnetized torus with major radius 5 m. The torioial vacuum chamber has a rectangular cross section that is 3 m tall and 2 m wide. Plasma is generated by a lanthanum hexaboride (LaB6) cathode discharge into a helical magnetic field produced by an approximately 200 G toroidal field and an approximately 6 G vertical field. Typical plasma density is ne about 1013 cm-3 and typical electron temperatues it Te about 10-20 eV. Increasing neutral pressure narrows measured plasma density cross-sections, implying pressure dependence of cross-field transport. Observed fluctuations show drift and interchange instabilities. The intensities of drift and interchange instabilities vary with neutral pressure, which possibly contributes to the observed changes in transport. This talk reports on work done in an REU project at UCLA during the summer of 2009.
Allyssa Stephenson
EIT with a Noisy Laser
Electromagnetically induced Transparency (EIT) is a quantum mechanical phenomenon in which light passes through an otherwise opaque material. EIT has applications in slow light, quantum memmory, and fiber optical communication. Our research uses noise spectroscopy to find ideal parameters for enabling EIT in Rubidium vapor, specifically focusing on the effects of laser beam power. This talk reports on work done in an REU project conducted at Lawrence University during the summer of 2009 and supervised by Professor Shannon O'Leary.
Dr. Orozco will be on campus all day Wednesday and until 4:00 PM or so on Thursday. Check with Professor Brandenberger to make appointments to chat with him or join him for lunch. DDr. orozco will give two talks during his visit:
We 28 Oct 7:30 PM Y-121: Science Hall Colloquium
Waves and Particles of Light
Professor Orozco will review the long and tangled history of the nature of light. Isaac Newton thought light was corpuscular; Thomas Young and Clark Maxwell and most 19-th century physicists believed light to be wavelike; Max Planck, Albert Einstein, and numerous other 20-th century physicists concluded that light can behave as either a particle or wave. Professor Orozco, an expert on the way that radiation interacts with matter, will shed his own light on this topic---one of the richest topics in all of physics. A Distinguished Traveling Lecturer for the Division of Laser Science of the American Physical Society, Dr. Orozco is eminently qualified to discuss this subject with a general audience.
Th 29 Oct 11:10 AM Y-115: Physics Colloquium
Quantum Optics and Cavity QED
Professor Orozco will discuss his current research program involving atoms that pass through optical cavities within which only a few photons are trapped, or stronger beams of photons that pass through a trap that contains only a few atoms. Professor Orozco, an expert on these matters and quantum optics, will discuss these topics, which are a major interest in contemporary atomic and optical physics. A Distinguished Traveling Lecturer for the Division of Laser Science of the American Physical Society, Dr. Orozco will discuss these areas at a level understandable by undergraduates. Dr. Oozco supervised the Ph.D. work of Lawrence physics graduates Stephen Mielke, LU '92, and Wade Smith, LU, '98.
Simulating Polydisperse Materials with Distributions of Debye
Marie Milne, LU '10
The Cole-Cole model has been shown as an excellent approximation to true polydisperse materials; however, simulations of this model are difficult. Thus I investigate using distributions of the simpler Debye model represented by the method of polynomial chaos, to approximate multi-pole materials in a more computationally feasible way. This talk reports on work done during the summer of 2009 in an REU program at Oregon State.
Computational Modeling of Astrophysical Hydrodynamic Systems
Brad Bodee, LU '11, and Joe O'Halloran, LU '10
The origin of gas giant planets like Jupiter is greatly disputed. Observational data to date show the existence of 403 (up from 358 in August) exoplanets---planets which are not in our solar system, most of which are probably Jupiter-like. We use a 3-D hydrodynamics program to study one of the proposed planet forming mechanisms: the disc instability model, in which a gas planet is formed via interactions of spiral arms in a gravitationally unstable circumstellar disc of gas and dust. We know that most young, planet forming systems---including our own---are exposed to a variety of environmental factors such as the presence of a companion or star cluster. However, the vast majority of work by computational astrophysics groups assumes instead that such a disk is in a closed system consisting of only the disk and the star it surrounds,. This summer, our group has altered a state of the art solar system simulator to address this deficiency. We have focused on removing the commonly used assumption of vertical symmetry, with the goal of adding simulated companions or other perturbers as orbiting point masses. This will allow warping and vertically asymmetric heating and cooling. In today's talk, we will present results of our additions to the code. This talk reports on work done at Lawrence during the summer of 2009 and supervised by Professor Megan Pickett.
Photo Shoot: 4:15 PM (promptly) on or near the front steps of Downer Commons. Faculty members, seniors, and juniors leaving for engineering schools should meet in the courtyard for the taking of this traditional photo.
Annual Reception for physics graduates and their graduation guests. All those associated with the Department of Physics who happen to be in Appleton are invited.
Gathering for all physics majors and minors returning from reunion, providing an opportunity for those individuals to meet and greet both current and retired faculty members, learn of new initiatives in the Department, network with one another, and bring all attending up to date on their activities since graduation.