Fall 2015 Physics Colloquium

Wednesday, September 9th
The Glover Memorial Lecture
Rush Holt, American Association for the Advancement of Science, Former New Jersey Congressman

Q&A Session
Don't miss the chance to chat with one of the only Congressmen with a Ph.D. in physics in the history of Congress! After retiring from politics, Rush Holt became CEO of the AAAS (the world's larges scientific body) - a position he currently holds. His advocacy for science-informed policy is arguable more urgent now than ever.

3:00 p.m.
Tome Hall Library
Refreshments provided

Lecture - "Advancing Science"
7:00 p.m.
Anita Tuvin Schlechter Auditorium (ATS)

Sponsored by the Clarke Forum for Contemporary Issues and the Glover Memorial Lecture Fund and co-sponsored by the Churchill Fund and the departments of physics and astronomy, policy studies and political science.

Thursday, September 24th
Dr. X. M. Cheng, Bryn Mawr
"Probing Nanomagnetism Using Synchrotron X-ray Based Imaging"

Nanomagnetism, a discipline of studying magnetic phenomena unique to structures with dimensions in the submicrometer scale, is a particularly exciting area of research due to its fundamental role in physics as well as its potential technological applications. A great example is the discovery of the giant magnetoresistance (GMR) effect, an effect of spin-dependent scattering in a nanostructured layered composite. The discovery of the GMR effect, which was awarded the 2007 Nobel Prize for Physics, led the way to an explosion of interest in nanoscale magnetic systems that exploit it.   

The synchrotron based x-ray photoemission electron microscopy (PEEM), combined with the large resonant x-ray magnetic dichroism (XMCD) effect present at the L edges of transition metals, offers a very powerful tool to image magnetic configurations in magnetic nanostructures with both chemical and magnetic sensitivities. The pulsed nature of synchrotron radiation provides a natural ability to obtain temporal data with a time resolution related to the x-ray pulse width (typically between 50 and 200 ps), thus offering high sensitivity magnetic imaging with very high time resolution.  

In this talk, I will present our study of vortex dynamics in magnetic disks using time-resolved PEEM imaging. We have used x-ray PEEM in a pump-probe arrangement to image the response of magnetic vortices in lithography patterned Ni80Fe20 (Permalloy) disks to fast magnetic field pulses. In isolated Permalloy disks, we find a strong dependence of the magnetic vortex core relaxation behavior on the excitation amplitude, indicative of non-linear magnetization dynamics. We also studied vortex dynamics in planar equilateral triangular arrangements of three magnetic disks with varied center-to-center distances. The observed vortex motion including the frequencies of the vortices in the tri-disk arrangements differs from that of an isolated disk of the same dimension.

Noon
Tome 115
Pizza provided

Monday, October 12th
Informal Q&A Session with Priestley recipient Steven Strogatz
Don't miss the chance to chat with a famous mathematician and  nonlinear scientist! Steven Strogatz is the author of a number of best-selling books, including "Sync" and "The Joy of X", and he has appeared on NPR's radio lab, given a TED talk, and blogged for the New York Times.

3:00 p.m.
Tome Hall Library, 2nd Floor
Refreshments provided

and

Steven Strogatz, Cornell University
Priestley Lecture - "Synchronization in Nature"

Strogatz will discuss spectacular examples of synchronization in nature, from rhythmically flashing fireflies to crowds of pedestrians that inadvertently caused London's Millennium Bridge to wobble on its opening day.

Anita Tuvin Schlecter Auditorium (ATS)
7:00 p.m.
Reception to follow in ATS Lobby

Tuesday, October 13th
Steven Strogatz, Cornell University - Priestley recipient
"Small-World Networks in Science and Society"

Everyone is familiar with the small-world phenomenon: soon after meeting a stranger, we are often surprised to discover that we have a mutual friend, or that we are linked by a short chain of friends.  In this talk, I'll present evidence that the small-world phenomenon is more than a curiosity of social networks -- it is actually a general property of many networks found in nature and technology, ranging from nervous systems to the power grid and the Internet.  I'll also speculate about some of the broader implications of these findings (e.g., for the spread of infectious diseases), and will reveal the identity of the actor at the center of the Hollywood universe (it's not Kevin Bacon).

Noon
Althouse 106
Pizza provided

Thursday, October 29th
Student Research from Summer of 2015
Chris Fritz, Jacky Han, Hanyu Ma, Sahil Nayyar, Emily Whitaker

Real physicists do research, but you don't need a Ph.D. to participate. A number of Dickinson Physics undergraduates spent their summer working with professors in different locations across the country on a variety of research projects. In this colloquium, we will hear five students discuss their summer experiences.

Chris Fritz worked with Thomas Murphy and Rajarshi Roy at the University of Maryland's Institute for Research in Electronics and Applied Physics (IREAP). He used digital filters and field programmable gate arrays to study frequency interactions in an optoelectronic oscillator.

Jacky Han worked here at Dickinson with Lars English and Faustino Palmero, a visiting scientist from Seville, Spain. He built an Arduino system to measure experiments in coupled pendula, focusing on experimental tests of recent theoretical predictions.

Hanyu Ma spent her summer at Fermilab, in Batavia, Illinois, working with Craig Dukes from the University of Virginia and Sten Hansen from Fermilab. She used computer simulations of high energy delta rays to contribute to the design of the Mu2e detector currently being built at Fermilab.

Sahil Nayyar spent his summer at the Center for Nanoscale Science and Technology at the University of Illinois at Urbana-Champaign, working with Brent DeVetter under Rohit Bhargava. He worked on computer simulations using the discrete dipole approximation to characterize the optical response of metal nanostructures.

Emily Whitaker worked with David Reed and Ankur Desai at the University of Wisconsin–Madison. She built experiments to test the feasibility of repurposing a cost-effective probe for measuring lake ice depth.

Noon
Tome 115
Pizza provided

Tuesday, November 17th
Sigma Pi Sigma Induction Ceremony & Talk
Dr. Michelle L. Edwards '01
"Eyes on the Sky: Working for the World's Largest Observatories"

The universe is an immense four-dimensional laboratory and exploring it requires astronomers to constantly push the limits of technology. In the last 30 years, this has resulted in the construction of giant 8-10 meter ground-based telescopes, the development of laser-assisted adaptive optics systems, and the creation of massive cameras and spectrographs. This evolution has created ample employment opportunities at observatories around the world - and the next generation of 20-30 meter telescopes promises expanding horizons for this specialized subfield. In this talk, Michelle will discuss her experiences designing a near-infrared instrument for the Grant Telescopio Canarias (GTC) and working as a staff astronomer for two of the world's largest observatories, Gemini South and the Large Binocular Telescope (LBT).

4:30 p.m.
Tome 115

Dinner will follow at 6pm in HUB Social Hall West (must sign up for dinner by Noon on November 13th in Tome 201) or email millert@dickinson.edu

Monday, December 7th
Physics Senior Research Talks
Zephram Wolf - "CCD Photometry Calibration"

Like all research appartus, telescopes require calibration to ensure data taken doesn't feature effects unique to the instruments it's taken on. Using multiple linear regression, observed star magnitudes can be related to variations in atmosphere and star color to calibrate observations of well-studied standard stars; the resulting equations should then hold true for all objects. Data from Dickinson's affiliated NURO telescope in Flagstaff, Arizona was used to test this method, with the potential for it to be applied to the Britton Observatory on campus.

Matthew Brinckerhoff - "Observation of Two Eclipsing Binary Stars"

For his senior research project, he will observe two pairs of eclipsing binaries. The first, KIC 9851142, has total eclipses with Dor pulsations. He will attempt to validate the data on the stars mass, age and radius, as well ass observe the pulsations. As there are only 6 known eclipsing binaries known to have this type of pulsation, data on this star is important and thus useful to confirm. The second binary, ZZ Cyg, is a near-contact binary. Meaning the two stars are orbiting very close to each other. These binaries are especially interesting as they have unique properties that will help us better understand the model of stellar evolution and the origin of the universe.

Maxwell Patterson - "Standardizing Planetarium Displays in Introductory Astronomy Courses"

What advantage does a planetarium provide that a classroom does not? This presentation looks at the benefit of having a planetarium on campus, as well as some common misconceptions that we intend to correct through Dickinson's astronomy curriculum.

4:30 p.m.
Tome 115
Refreshments provided

Tuesday, December 8th
Physics Senior Research Talks
Kyle Liss & Sahil Nayyar - "Predicting Molecular Motion Using Time-Dependent Quantum Mechanics"

Predicting molecular vibrations and rotations is of interest in understanding transition states in chemical reactions. Such molecular motions however take place on minuscule time-scale of femtoseconds (10-15 seconds), and are thus inherently difficult to measure. only relatively recently (1990) have experimentalist developed femtosecond laser pulse techniques that enable us to observe these molecular motions in real-time. A primary goal of our research is to model the light-matter interaction and molecular dynamics that occur in femtosecond laser pulse experiments, which is most naturally done using a time-dependent perspective to quantum mechanics. In this presentation, we will describe our time-dependent approach to quantum mechanics and its application to understanding molecular motion.

Zhuwei (Zoey) Zeng & Adrian Stone - "Light Pollution in Carlisle: Characterization and Analysis"

How abundant is light pollution in the Carlisle area? This presentation begins to characterize the light pollution in Carlisle as well as explaining the steps necessary in doing so. An analysis of current ordinances related to outdoor nighttime lighting will be included. Possible ordinance improvements will be explored and discussed.

Noon
Tome 115
Lunch provided

Thursday, December 10th
Physics Senior Research Talks
Hanyu Ma - "The Study of Collective Phase Dynamics of Coupled Wien-Bridge Oscillators"

The spontaneous synchronizations in nature have always been fascinating. In the lab, studies show that the collective phase dynamics of resistively coupled Wien-bridge oscillators displays interesting patterns and are consistent with the Sakaguchi-Kuramoto model. In this senior research, we present experimental findings for dynamics of rings of oscillators, uni-directionally coupled. We also briefly discuss the case of bi-directional coupling, in which case chimera state is expected.

Nicole Fronsdahl & John Root - "Investigation of a Solar Air Heater and Grid Efficience"

Solar air heaters are renewable energy devices that use solar energy to heat buildings. Solar air heaters are becoming more popular as a means to reduce fossil fuel dependence. Compared to photovoltaic cells, they have up to four times higher conversion efficiencies. Last spring, a new and improved solar air heater was built by Professor Hans Pfister, Jonathan Barrick, and Tyler Ralston. Our talk will focus on describing this new solar air heater, how it compares to others, factors that affect conversion efficiency, and our plans to optimize its absorber grid efficiency.

Noon
Tome 115
Lunch provided