Spring 2010

January 22, 2010
"Counting the Cycles of Light: Using Optical Frequency Combs to Study Atoms" by Dr. Jason Stalnaker, Department of Physics and Astronomy, Oberlin College
3:10 pm
Franklin Miller, Jr. Lecture Hall (RBH 109)
Abstract: Optical frequency combs are a revolutionary new type of laser that allow one to count the frequency of light. These lasers have changed the face of atomic spectroscopy and have resulted in some of the most accurate measurements in all of physics. I'll explain how optical frequency combs work and how we're using them to study atoms at Oberlin College. Reception to follow.

February 5, 2010
"Low-Energy Electron Diffraction (LEED) as a Tool for Deciphering the Atomic Arrangement of Solid Surfaces" by Dr. Mellita Caragiu, Department of Physics and Astronomy, Ohio Northern University
3:10 pm
Franklin Miller, Jr. Lecture Hall (RBH 109)
Abstract: The use of the LEED technique is justified by the precise structural information that it provides when applied to the study of solid surfaces. The way that structural information is obtained is by an indirect method of comparison between experimental data (intensity of an electron beam back-scattered by the sample versus its energy) and sets of calculated such intensity versus energy - I(E) - curves which correspond to models which would mimic the real structure under study. The talk concentrates on the computational aspect of LEED and uses as an example the study of a somewhat complex surface: a stepped Cu surface (Cu(511)). Reception to follow.

February 19, 2010
"Understanding and Forecasting the Sun's Impact on the Space Environment" by Dr. Jill Dahlburg, Space Science Division, Naval Research Laboratory
3:10 pm
Franklin Miller, Jr. Lecture Hall (RBH 109)
ABSTRACT: The atmosphere of the Earth extends far above the surface of our planet. Of special interest to space science are the outer layers of the Earth's atmosphere, from altitudes 100 to 1000 km, where there is sufficient density to impede the motion of Earth-orbiting spacecraft, and where layers of charged particles control the propagation of radio waves. Changes in atmospheric "drag" alter the orbits of the thousands of space objects in low Earth orbit (LEO). The ionosphere reflects, scatters, absorbs, retards, refracts and rotates kHz to GHz radio waves. As a result, fluctuations in the neutral and ionized environment can negatively impact terrestrial communications and navigation, and degrade GPS accuracy and satellite orbit prediction. Increasingly sophisticated models, data, databases, and forecasting indices are refining our understanding of the intricately interconnected Sun-Earth system, thereby improving the ability to predict this region's impact. This talk addresses current research and future directions in Sun-Earth system space experiments and associated modeling at the Naval Research Laboratory.

February 26, 2010
"Making Sport of Physics" by Dr. John Eric Goff, Physics Department, Lynchburg College
3:10 pm
Franklin Miller, Jr. Lecture Hall (RBH 109)
Abstract: I will discuss how a physicist approaches research into the realm of sports. Specific examples will be taken from my new book, Gold Medal Physics: The Science of Sports (The Johns Hopkins University Press, 2010). I will also present work I performed on soccer balls as a visiting academic in the Department of Mechanical Engineering at the University of Sheffield (UK) during the 2008-09 academic year. Reception to follow.

March 26, 2010
"Synthesis and Characterization of Zinc Manganese Ferrite Nanostructures" by Andrew Borrasso, '10
3:10 pm
Franklin Miller, Jr. Lecture Hall (Hayes 109)
Please join us for Andrew Borrasso's senior exercise talk. Abstract: Zinc Manganese Ferrite is a prototypical soft magnetic material. It is commonly used for high-frequency applications due to its low power loss as well as its high permeability and resistivity. Using a novel synthesis process, fine powders of various stoichiometries and several thin films were created. In this talk, I will introduce the physics of X-Ray diffraction used to characterize and identify these samples. I will also discuss the physics of super conducting quantum interference devices, which were used to characterize the magnetic properties of the as synthesized Zinc Manganese Ferrite. Reception to follow.

March 26, 2010
"The Physics of Infrared Detectors " by Megan Kirkendall, '10
3:10 pm
Franklin Miller, Jr. Lecture Hall (RBH 109)
Please join us for Megan Kirkendall's senior exercise talk. Abstract: The detection of infrared light is very important for astronomy and imaging parts of the universe previously hidden from us. In this talk we will explore several different types of infrared detectors. We will discuss the physics of these detectors, how they are constructed so that they can view infrared in the near, mid and far ranges, and we will see some of the amazing images and discoveries that these detectors have made possible. Reception to follow.

April 1, 2010
Donald B. Hamister Distinguished Lecture in Physics - "The Discovery of Dark Energy: How and Why We Had to Re-Think the Universe," by Dr. Meg Urry, Yale University
7:30 pm
Kenyon College Athletic Center Theater
Dr. Meg Urry is the Israel Munson Professor of Physics & Astronomy at Yale University. Abstract: Toward the end of the 20th century, we thought we understood nearly everything about our universe: its history and the fundamental physical laws governing it. This is much the same as the situation at the end of the 19th century, when we thought we had a similar understanding of physics - only to embark on one of the greatest scientific revolutions ever, with the invention of quantum mechanics and the characterization of sub-atomic matter and nuclear processes. Over the past decade, astrophysics has generated a similar revolution in our view of the Universe and of fundamental physics. I will tell the story of the discovery of the accelerating universe and the mysterious "dark energy" causing its acceleration, and how we are re-thinking the nature of the world in which we live. Reception to follow.

April 2, 2010
"Supermassive Black Holes and Galaxy Evolution," by Dr. Meg Urry, Yale University
3:10 pm
Franklin Miller, Jr. Lecture Hall (Hayes Hall room 109)
Dr. Meg Urry is the Israel Munson Professor of Physics & Astronomy at Yale University. Abstract: Black holes form in the early Universe and grow to billions of solar masses as their gravity attracts surrounding matter. This cosmic accretion releases a huge amount of energy, which is expected to have a strong influence on galaxy evolution -- for example, potentially ionizing the interstellar gas and thus quenching star formation. The history of black hole growth can be traced through the detection of Active Galactic Nuclei out to very high redshifts; however, most AGN have been discovered in optical and ultraviolet surveys, which are strongly biased against obscured accretion. Deep multiwavelength surveys reveal that most AGN are heavily obscured and that obscuration is more common in the young Universe and in low-luminosity AGN, so we now have a much more complete picture of the demographics of supermassive black holes. Perhaps unexpectedly, star formation appears to turn off well before AGN reach their peak brightness, which is an important clue to the role of AGN feedback in galaxies. Reception to follow.

April 9, 2010
"Blue Skies: Rayleigh Scattering and the Physics of Color Vision" by Benjamin Kester, '10 - Senior Exercise Talk
3:10 pm
Franklin Miller, Jr. Lecture Hall (Hayes 109)
Please join us for Benjamin Kester's senior exercise talk. Abstract: Did you ever wonder why the sky is blue? Most physicists will happily explain the effects of Rayleigh scattering from molecules in the upper atmosphere, but we should not neglect the role of human color vision. In this lecture, I'll introduce you to the anatomy of the human eye and give you a quantitative look at the physics behind color vision. We will explore atmospheric optics and the path of scattered photons through the upper atmosphere. Then we will take a look at the spectral sensitivity of the human eye to better understand our perception of light and color. Reception to follow.

April 9, 2010
"Hall Effect Devices: Theory and Applications" Senior Exercise Talk by Justin Rhodes, '10
3:10 pm
Franklin Miller, Jr. Lecture Hall (Hayes 109)
Please join us for Justin Rhodes' senior exercise talk. Abstract: The Hall effect was first observed by Edwin Hall in 1879. Since that time, the Hall effect has found uses in everything from cell phones to cars. In this talk, the Hall effect will be derived from basic physical principals. After the derivation, several "problems" with the Hall effect will be examined, most of which result in very low sensitivity to magnetic fields. Amplifiers will be discussed as a possible means of integrating a Hall effect device into a practical application, and both the hardware and software aspects of interfacing to a Hall effect device will be worked out. By the end of the talk, the main problems will have been solved and a working demonstration of the Hall effect device, as used in a force probe, will be presented. Reception to follow.

April 16, 2010
"Quantum Tornados" Senior Exercise Talk by Melanie Holden, '10
3:10 pm
Franklin Miller, Jr. Lecture Hall (Hayes 109)
Please join us for Melanie Holden's senior exercise talk. Abstract: Superfluids are a unique form of matter. They are a macroscopic quantum state, which leads to many strange properties. We will examine these properties in depth, leading up to the derivation of a wavefunction. This wavefunction contains a gradient, so that the curl of a superfluid must be zero. However, we will see that this does not prevent superfluids from rotating under special circumstances. The resulting "quantum tornados" behave in interesting ways. Examining superfluids shows that quantum mechanics are not limited to minute objects, but can also be seen at a macroscopic scale in low temperatures. Reception to follow.

April 16, 2010
"The Fourth State of Matter Inside a Television," by Jacob Shanley, '10
3:10 pm
Franklin Miller, Jr. Lecture Hall (Hayes 109)
Please join us for Jacob Shanley's senior exercise talk. Abstract: Most people today are more familiar with the three most common types of matter: solids, liquids, and gases. Plasma, however, is also encountered within everyday life. The high electrical conductivity of plasma gives it properties that are unlike the common three matter states, and is thus sometimes considered to be a distinct fourth state of matter. This discussion will focus on how to create a plasma and use its properties in such a way to create the giant flat screen plasma display panels that are found today. Reception to follow.

April 23, 2010
"Ultracold Atomic Gases" by Dr. Mohit Randeria, Physics Department, The Ohio State University
3:10 pm
Franklin Miller, Jr. Lecture Hall (RBH 109)
Abstract: In this talk I will give an introduction to the exciting new field of ultracold atomic gases. This field is at the intersection of many different areas of experimental and theoretical physics and has seen an explosive growth in activity in the past 15 years. Using lasers to manipulate atoms has led to the coldest temperatures ever achieved, new phases of matter like Bose-Einstein condensates, and unexpected novel phenomena like "perfect fluid" behavior. I will not assume any knowledge of quantum mechanics, and will explain all the technical terms that I use!

April 30, 2010
"Observing Projects from the Miller Observatory at the Brown Family" by Alex Carroll, '10; Christopher Simon, '10; Todd Skinner, '11; Samantha Turner, '10
3:10 pm
Franklin Miller, Jr. Lecture Hall (RBH 109)
Abstract: Imaging and spectroscopy are the predominant techniques astronomers use to gather information on astronomical objects. When combined with physical theory and laboratory measurements, such observations have led to our rich and ever-expanding understanding of the physical nature of stars, nebulae, and galaxies. Once the purview only of research astronomers, electronic imaging and spectroscopy are now widely available even to serious amateur astronomers. In this talk, students whose prior experience ranged from one or two "non-science-major" astronomy courses to several physics courses and an intensive introduction to observational astronomy through the CUREA program (see curea.org) will present results of individual study projects they have completed this semester. Using techniques including broad- and narrow-band filter imaging and low resolution spectroscopy, these students have made observations of ionized gas in a variety of types of regions including ionized hydrogen gas clouds, planetary nebulae, and stellar atmospheres. In presenting their observations, the speakers will explain a bit about these astronomical sources as well as the process of making their observations. Reception to follow.

May 7, 2010
"Let There Be Light " by Thomas Greenslade, Professor Emeritus of Physics
3:10 pm
Franklin Miller, Jr. Lecture Hall (RBH 109)
Abstract: On the end wall of my Apparatus Museum in Gambier is a 1939 "Map of Physics" by Cenco. The corner devoted to Optics is pretty bare, and my aim is to fill it in with fascinating images and ideas that I have discovered in my own trips through the Land of Physics. Be prepared to see the biggest telescope in the world (in 1845!), early Egyptian Photography, a huge magnifier filled with fish, a tooth camera, a method for putting ghosts into your plays, reflections in my 1890 wedding ring, and the technique of photographing yourself again and again and again... Reception to follow.