Fall 2010 Physics Colloquium

Unless otherwise noted, lunch is served 15 minutes before each colloquium.  Colloquium schedules from other semesters can be found at the *Colloquium Archive*.

Thursday, September 9, 12:05 pm - Tome 115
Kristen Recine - "The CHAI Project: Coordinates for Hubble Astronomical Images" - The purpose of her summer project was to make Hubble Space Telescope (HST) press release images available to programs such as GoogleSky and WorldWide Telescope, so that users of these programs will have easy access to HST images.  She spent her entire time working in the Space Telescope Science Institute press release archive, where color-composite "pretty" pictures made from HST images are released. She used software entitled "PinpointWCS" to embed coordinates in the press release image by comparing it with the original science FITS file.  In addition, she began the process of tagging the press release images with Astronomy Visualization Metadata.  This will make it easier to search for and get useful information from the image headers.

Christine Welling - "Broad Absorption Line Variability in Radio-Loud Quasars" - Her summer project examined broad absorption line variability over time in a sample of twenty radio-loud quasars.  She wrote programs in IDL to calculate the change in equivalent width of the C IV broad absorption line for each object between two epochs.  They compared radio properties of the quasars to broad absorption line variability with time.  They also compared the broad absorption line variability in the radio-loud quasar sample to the broad absorption line variability in three samples of radio-quiet quasars.  This information can be used to learn about the physical structure of quasars, as well as to determine differences between radio-loud and radio-quiet quasars.

Morgan Cheatham - "Reflectance of Coated Mirrors" - Her summer project was writing code in Matlab to calculate the reflectance of multilayer high reflectance mirrors used in gravitation wave detectors.

Thursday, September 23, 12:05pm - Tome 115

Dr. Kurt Andresen - Gettysburg College - Biophysics
"DNA Packing: The Physics of Strangely Attractive Molecules"

Abstract: Opposite charges attract; like charges repel.  These are fundamental rules we are taught very early in our science education.  Yet these rules break down when we put highly charged biomolecules in solution.  In these solutions, the charge of the biomolecules, the charge of the ions surrounding them, and even the dipole nature of water all contribute to complex electrostatic behavior.  In this talk, he will explain how our simple rules of electrostatics are modified in these solutions and how both like-charged and oppositely-charged biomolecules are attractive under certain conditions.  We will see that this attraction between like-charged objects is important to DNA packing, gene regulation, and stem cell research.

Tuesday, October 5, 12:05pm - Tome 115
Dr. Sunil Acharya - "@Q Services"
"Trends in Applied Computational Physics"

Abstract:  Increasing availability and use of computers in solving physics problems numerically (as opposed to analytically) has made computational physics a prominent and popular tool of our times.  In the last 20 years, the computational speed and cost-effectiveness has reached the point where computational physics has now become ubiquitous in industry applications.  Consequently, these simulation tools are being introduced to students at undergraduate science levels.  The talk aims to illustrate the utility of computational physics with some examples from real world engineering applications.

Thursday, October 28, 12pm - Rector's Stafford Lecture Rm - Stuart 1104
Professor Brett Pearson, Physics & Astronomy, Dickinson College
"Exploring the Nature of Light"

Abstract:  Light and its interactions with matter lie at the heart of much of modern science, with applications such as spectroscopy in chemistry and astronomy, photosynthesis in biology, photonics in solar energy, and imaging in the medical sciences.  Although the nature of light has been discussed for centuries, it is still not completely understood.  In fact, different experiments seem to point toward either a classical (wave-like) or quantum-mechanical (particle-like) description.  Fortunately recent advances in technology have decreased the complexity of tests probing the nature of light, and we describe a set of experiments whose primary motivation is bringing undergraduate students face to face with some of the fascinating and subtle aspects of quantum mechanics in a hands-on setting.

Tuesday, November 2, 12pm - Rector's Stafford Lecture Rm - Stuart 1104
Dr. Bruce E. White, Jr.
"Nanotechnology in the Semiconductor Industry"

Abstract:  In 1959, Richard Feynman presented his "There's Plenty of Room at the Bottom" lecture to the American Physical Society, spawning the field of nanotechnology.  In that lecture, Feynman touched on two themes that have become critical for the semiconductor industry.  The first theme emphasized the tremendous improvements in computational performance that could be obtained by the reduction in size of the elements required to build computers.  The second theme touched on the opportunities for creating new forms of matter through the manipulation of materials at the atomic level.  Here, we will discuss the current realization of these ideas for information processing.  In particular, this lecture will cover the utilization of layered perovskites, quantum dots, and spin dependent electron tunneling as the basis for new memory technologies.  In the areas of advanced transistors, the lecture will cover the creation of "new" forms of silicon through the manipulation of local strain to enhance carrier transport as well as the manipulation of surfaces required for the implementation of high dielectric constant materials as gate insulators in transistors.  The lecture will conclude with some speculation on future nanotechnology that could enable the continued increases in device performance and functionality observed in the industry over the last forty years.

Tuesday, November 16, 4:30pm
Sigma Pi Sigma Presentation  & Keynote Speaker: Michael Deceglie '06 -  in Tome 115

"Next Generation Silicon Solar Cells: Crystals Without Wafers"

Abstract: A major cost in solar cells made from silicon, the most widely used photovoltaic material, comes from the crystalline wafers from which the cells are made.  We present two routes to eliminating the wafer from crystalline silicon photovoltaics.  First, we discuss low temperature epitaxial hot-wire chemical vapor deposition, a technique in which hydrogen introduced during silicon deposition facilitates growth of crystalline material at temperatures as low as 250 degrees Celsius.  At these temperatures, low cost materials such as glass can be used as solar cell substrates.  Another route to eliminating the wafer from silicon photovoltaics is the microwire solar cell.  Ordered arrays of high quality crystalline silicon microwires can be grown using a metal catalyzed vapor liquid solid growth mechanism.  These wire arrays can then be embedded in a polymer and removed from the growth substrate to yield a flexible photovoltaic materials.  We will also discuss the optical and electronic properties of both of these materials and describe designs for efficient light will also discuss the optical and electronic properties of both of these materials and describe designs for efficient light collection and energy conversion.

Followed by Dinner in the Holland Union Building Social Hall West Section

Monday, December 6, 4:30pm - Tome 115
Senior Research Talks! 

Kristen Recine - "A Mysterious Light Curve: Studying the Star V723 Cassiopeia".
Abstract: Many Dickinson College students have studied the star V723 Cas over the past 4 years.  Originally, we observed this star because it is a super soft source (SSS) and could be a Type 1a supernova progenitor.  Current research and analysis of past results show that, while V723 Cas is still a SSS, it may not be a supernova progenitor.  Therefore, it is necessary to come up with new theories to explain what we see when we look at the light curve of V723 Cas.  In this talk, she will provide a brief background of the V723 Cas system, explain the work she did this semester, and present some thoughts on what may be happening to V723 Cas.

Paulo Candiani - "A Novel Route Towards Energy Localization & its Manipulation in an Electrical Lattice"
Abstract: It was shown recently that a uniformly driven nonlinear electrical lattice can exhibit spontaneous localization of energy.  Here we present a novel route towards this localization by using sub-harmonic driving.  We have experimentally demonstrated that localized modes (also known as ILMs) can be exited through a parametric down conversion process.  Furthermore, using the same system we explore the spatial manipulation of these modes via their interactions with impurities in the lattice.

Tuesday, December 7, 12pm - Tome 115
Senior Research Talks!

Brian Wysowki - "Mapping Out the ion Velocity Distribution Function Fi(v) in the Plasma of the Dickinson Hall Thruster"
Abstract: Plasma thrust is presently used in deep space applications and for satellite station keeping.  It is highly efficient and has the benefit of providing long lasting thrust without a large mass of fuel.  My research goal is to map the thrust of the Dickinson hall thruster.  To do this I will design and build an ion velocity analyzer known as a retarding field energy analyzer.  There are many factors that go into designing such a device and all of them are vitally important to the resolution and accuracy of the ion velocity distribution I hope to find.  In my talk I will provide a proper background in Hall thruster operation and give the details of how I plan to reach my research goals.

Matthew Murray - "The Shaping of Ultrafast Laser Pulses"Abstract: The field of ultrafast laser optics addresses a growing need in the physical sciences: to accurately measure a fast event or phenomenon, a faster method of observation is required. For example, a photograph of a racecar speeding around a track will appear blurry if the shutter speed of the camera is not fast enough. The human eye is generally quick enough to resolve on the millisecond (10-3) timescale and modern electronics has pushed this limit to nanoseconds (10-9). The fastest time currently measurable with ultrafast optics is on the order of attoseconds (10-18), which is fast enough to measure the formation of bonds and the transfer of electrons in chemical reactions. Our current research uses an accousto-optic modulator (AOM) to split an incoming laser pulse into two pulses that are then sent through a liquid crystal spatial light modulator (SLM). The SLM allows for the manipulation of certain wavelengths in a pulse, which in turn alters the temporal domain and overall shape. Finally, the beam is recombined by the AOM and the characteristics of the two pulses can be determined using spectral interferometry.

Thursday, December 9, 12pm - Tome 115
Senior Research Talks!

Anubhav Mohan, Melissa Kelly & Kent Pecora will present "The Top Secret TM Perpetually Spinning Top Explained"Abstract: In this talk, they will lift the veil of secrecy surrounding the "perpetually spinning top".  When you first see this toy in action, it appears to be governed by magic.  Could this toy really be defying the laws of physics? No!  We will reveal the inner workings of the spinning top, and in the process take you on a tour of physics - from mechanics, via electronics, to electromagnetism.