Spring 2016 Physics Colloquium

Thursday, February 25th
Dr. James Puckett, Gettysburg College
Instrinsic Fluctuations and Driven Response of Insect Swarms

Much of our understanding of collective behavior in social animals comes from passive observations of animal groups. To understand the group dynamics fully, however, we must also characterize the response of animal aggregations to disturbances. Using three-dimensional particle tracking, Dr. James studies both the intrinsic fluctuations of laboratory swarms of the non-biting midge and the response of the swarms to controlled external perturbations: the amplitude-modulated sound of male midge wingbeats. Although these perturbations have an insignificant effect on the behavior of individuals, they can have a strong impact on the collective movement. Intriguingly, the response of the swarm is similar to that of a passive equilibrium system to an external driving force, with microscopic fluctuations combine to produce a macroscopic linear response over a wide range of driving frequencies.

12:00 p.m.
Tome 115
Lunch provided

Thursday, March 10th
Dr. Brigett Hesman, University of Maryland
"Saturn's Great Northern Storm of 2010-2011: From Storm Clouds to Hot Vortices"

The massive eruption at 40ºN on Saturn in December 2010 has produced significant and lasting effects in the northern hemisphere on temperature and species abundance. When the storm clouds erupted into the troposphere of Saturn they were sheared and over the next 3 months wrapped around the entire planet. This eruption sent waves into the stratosphere, which caused significant heating. In 2011 and 2012 the Cassini spacecraft observed the effects of the storm over many wavelengths on multiple occasions. The Composite Infrared Spectrometer (CIRS), on Cassini, "chased" the storm in order to follow the unexpected changes in the normally quiet stratosphere. This talk will discuss the "beacons" in the stratosphere that resulted from the storm, how these beacons changed over time, the changes in the amounts of hydrocarbons, and what effects Cassini was able to "see" in the northern hemisphere long after the storm clouds subsided.

12:00 p.m.
Tome 115
Lunch provided

Thursday, March 24th
Dr. Lyle Hoffman, Lafayette College
"ALFALFA: A Large-scale Extragalactic Survey of the 21 cm Sky"

The Arecibo Legacy Fast ALFA (ALFALFA) survey is a large project undertaken by a consortium of 122 researchers from 72 institutions worldwide, led by Giovanelli and Haynes of Cornell University. The survey spans 7000 square degrees of high-Galactic latitude sky visible from Arecibo, seeking extragalactic neutral hydrogen out to a redshift of 17,600 km/s without regard to the location of galaxies known from their optical emission. In addition to the neutral hydrogen contents of some 37,000 galaxies, we detect a number of (almost) dark galaxies and many tidal features. Follow-up studies to confirm or refute marginal detections, to assess the effects of environment in galaxy groups, and to study the infall of galaxies onto the Pisces-Perseus filament, are being conducted by the Undergraduate ALFALFA Team of about 28 college faculty from 25 mainly bachelors-granting institutions along with their undergraduate research assistants.

12:00 p.m.
Tome 115
Lunch provided

Thursday, March 31st
Priscilla Laws, Research Professor of Physics
"Online Interactive Video Vignettes (IVVs)"

Interest in on-line learning is increasing rapidly. A few years ago members of the LivePhoto Physics Group1 received collaborative NSF grants2 to create short, single-topic, on-line activities that invite introductory physics students to make individual predictions about a phenomenon and test them through video observations or analysis. Each Vignette is designed for web delivery as: (1) an ungraded homework assignment or (2) an exercise to prepare for a class or tutorial session. Sample IVVs are available at the ComPadre website http://www.compadre.org/ivv/.  Portions of Vignettes on mechanics topics including Projectile Motion, Circular Motion, the Bullet-Block phenomenon, and Newton's Third Law will be presented. Those attending this talk will be asked to guess what predictions students are likely to make about phenomena in various IVVs. These predictions can be compared to those made by students who completed Vignettes. Finally, research on the impact of Vignettes on student learning and attitudes will be discussed.

1. Co-PI Robert Teese, Rochester Institute of Technology
2. NSF #1122828 (Dickinson College) & NSF #1123118 (Rochester Institute of Technology)

12:00 p.m.
Tome 115
Lunch provided

Thursday, April 14th
Anne White - MIT Department of Nuclear Engineering
"Nuclear fusion: Energy technology development with tantalizing potential to completely redefine the world's energy suppy system"

Bringing the stars down to earth is one of the great scientific challenges of the 21st century. The controlled fusion of isotopes hydrogen into helium represents an essentially inexhaustible source of energy for society and remarkable progress has been made in attaining that goal by building new understanding of the still-mysterious conditions inside the tokamak, the experimental test bed where fusion reactions occur at temperatures exceeding 100 million degrees. The ITER tokamak, currently under construction in France, is designed to deliver 500 megawatts of output from 50 megawatts of input power for several minutes at a time. Success would open the door to a large-scale source of continous power with no carbon emissions or hazardous waste problems, and fuel that could largely be extracted from ordinary seawater. Work on existing tokamaks is largely focused on the grand challenges of susion: the need to contain an ongoing fusion reaction, create a stable "burning plasma" that can maintain its own temperature, and capture its massive heat output for electric power generation. Containing a stable plasma at high temperatures is a challenge because the fusion plasma supports many waves and instabilities, some leading to turbulence, which very effectively resitributes heat and particles in the plasma, inhibiting attainment of parameters needed to achieve a burning plasma. Advanced simulations are being used to make predictions about turbulence parameters, the predictions are being compared to results from newly developed plasma turbulence diagnostics, and models of plasma confinement and performance are being developed that steer the experimental optimization of plasma confinement and control. This talk will introduce basic plasma physics behind fusion energy development, discuss science and technologies of the leading fusion plasma confinement device, the tokamak, and will describe recent advances in understanding turbulent transport from MIT's Alcator C-Mod tokamak.

12:00 p.m.
Tome 115
Lunch provided

Thursday, April 14th
31st Annual Science Student Research Symposium
Poster Session & Refreshments

Abstract deadline is Thursday, April 7th - email wissj@dickinson.edu

4:30-6:00 p.m.
Social Hall

Monday, April 25th
Senior Presentations
Matt Brinckerhoff - "Photometric Observations of an Eclipsing Binary in NGC 2362"

We present photometric observations of a newly discovered eclipsing binary in the young cluster NGC 2362. The binary was discovered in 2006 based on observations taken with the 0.9-m telescope at McDonald Observatory. In an effort to confirm the binary period of 0.612 days, we began observations in January 2016 at the NURO telescope in Flagstaff, AZ, and at the Michael L. Britton Observatory on the campus of Dickinson College. An analysis of the light curve and this system's importance in testing theoretical evolutionary models will be discussed.

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

The difficulty for students in introductory astronomy courses stems from trying to grasp three-dimensional concepts in a classroom setting. This is why the Dickinson College Department of Physics and Astronomy believes strongly in the value the Kanev Planetarium brings to astronomy courses. The Spitz ATM-4 model gives instructors the tools to create "mini-shows," which are programs that play back demonstrations. The goal of this research was to create several shows to be used for the astronomy courses Dickinson offers. Currently, three projects are ready for display, and a fourth project is in progress. These shows were suggested by Professor Robert Boyle, who stresses their value at the introductory course level. All of these shows target misconceptions that an introductory astronomy student would generally believe prior to taking the course. Ultimately, we hope these shows will become a staple of the introductory astronomy curriculum. No matter what professor teaches the course, we hope that each student taking the course will be shown these programs.

Zephram Wolf - "CCD Phtotometry Calibration"

The process for the calibration of Charged-Coupled Devices (CCDs) is well-known, but the CCD at Dickinson's Britton Observatory had not yet been calibrated. This project used the Landolt standard star fields RU149, PG0231, SA100, and PG1047 to take a series of images in the specific filters, which returned magnitudes for the stars making up those fields in the respective filters' colors. To ensure that the data was useable, images called biases, darks, and flats were taken; the former two measure electrical offset and thermal noise respectively, while the latter captures a zero-contrast portion of the sky to allow corrections for uneven response of the CCD due to sensitivity variations or shadowing due to dust on the CCD window or the filters. The image analysis program IRAF (Image Reduction and Analysis Facility) was then used to remove the offset, thermal noise, and response variations from images, allowing the data to be extracted. Finally, Microsoft Excel's statistics package was used to generate multiple linear regressions for each filter's data, returning an equation that can be used to correct Britton Observatory CCD star brightness data to the standard system. All of this was carried out on both data taken this semester in the Visible (V), Infrared (I), and Red (R) Bessel filters with the Britton Observatory, and 2014 data taken in the Blue (B) and V by Justin Brown '14 at the NURO 31 telescope on Anderson Mesa near Flagstaff, AZ.

4:30 p.m.
Tome 115
Refreshments provided

Tuesday, April 26th
Senior Presentations
Hanyu Ma - "Experimental Studies of Synchronization in Coupled Wien-Bridge Oscillators"

Wien-bridge oscillators are RC coupled amplifier circuits, very stable at its resonant frequence. When coupled resistively, these oscillators are shown to follow the Kuramoto-Sakaguchi model. In this project, we present experimental findings for the dynamics of rings of oscillators with several distinctive topologies, mainly the uni-directionally coupled oscillators that are set up to have identical natural speeds. We started with 4 oscillators in line configuration then move to ring configuration and expand the ring to 8 and 32 oscillators. The frequency of one oscillator will influence the next coupled neighbor. We find that the system quickly approaches a steady state of identical nearest-neighbor phase offsets and display interesting coupling patterns.

Adrian Stone and Zoey Zeng - "Light Pollution in Carlisle: Characterization and Analysis"

This presentation will explore the abundance and impact of light pollution in the Dickinson College area and Carlisle as a whole. Our areas of focus will be plotting night sky brightness as a function of distance from both Michael L. Britton Observatory and the intersection of High Street and Hanover Street, and calculating the relative brightness of the various light sources found across Dickinson's campus. We will conclude with an analysis of our data and a discussion of possible improvements the college and the town can make to decrease the abundance of light pollution in Carlisle.

12:00 p.m.
Stafford Lecture Room
Lunch provided

Thursday, April 28th
Senior Presentations
Nicole Fronsdahl and John Root - "Investigation of the Conversion Efficience and Output of a Gridded Solar Air Heater as a Function of Mass Flow Rate and Grid Number"

A Solar Air Heater (SAH) is a device that converts solar energy into thermal energy in the form of hot air with high efficiencies of up to about 80%. Solar energy enters the SAH through a glazing and heats a specially designed absorber, in our case several blackened, corrugated aluminum mesh grids, which transfer their thermal energy to the air. Here we present the experimental and theoretical investigation of the optimal number of grids that maximize efficiency and minimize the return on investment period (ROI). A higher number of grids increases the absorption and output temperature, yet also increases flow resistance in the device. Our experimental investigation finds that four absorber grids result in an optimal SAH performance and the shortest ROI of the device

Kyle Liss - "A Numberical Study of Multi-Dimensional Molecular Motion"

A fundamental question in molecular dynamics is the following: Given some bond-localized excitation of a molecule, what will be the pathway and rate of energy flow throughout the molecule’s various degrees of freedom? This notion of vibrational energy transfer throughout a molecule is referred to as intramolecular vibrational redistribution (IVR) and has been a long-standing subject of interest in physical chemistry. Historically, IVR has been studied on a case-by-case basis. However, the essence of IVR for any molecular system is an anharmonic potential energy surface that causes dynamics in which the system’s many degrees of freedom are coupled in any coordinate system.

We perform a general study of anharmonic coupling by examining the dynamics resulting from the lowest order power series potential that causes coupled motion. Specifically, we consider both quantum and classical simulations starting with a localized excitation in a single vibrational mode. We analyze the quantum case in low dimensions, while in the classical case we study simulations where the initially localized energy is coupled to a large dimension bath. For a specific coupling model and system dimension, we observe energy dephasing into the bath that agrees with results from experimentally observed IVR. However, we find the unexpected result that once the size of the bath reaches a certain critical value, increasing the dimension further causes the energy in the system to remain more localized. 

Sahil Nayyar - "The Numerical Simulation of Femtosecond Transition-state Spectroscopy Applied to 2 Using Split-operator Fourier-transform Propagation Methods"

Simple molecular motions, such as vibration and rotation, drive the chemical reactions that govern the world in which we live. In an attempt to understand the underlying mechanisms of these processes, scientists have developed a multitude of ultrafast spectroscopic techniques that allow us to observe these fundamental motions. Femtosecond transition-state spectroscopy (FTS) is such a technique that uses a pump-probe laser method to monitor changes in the conformation of molecular systems, notably interatomic distance or vibration. There have been several studies in which this technique was used to monitor the vibration of diatomic iodine (I2), with the resulting data giving insight to experimentalists and theorists alike.

We present the underlying theory, development, and results of a MATLAB-implemented numerical simulation of FTS applied to I2. Our time-dependent quantum mechanical calculations simulate all aspects of the I2-FTS system, taking into account both wavepacket evolution along molecular potential energy surfaces and the laser-driven transitions between these surfaces. We directly integrate the time-dependent Schrodinger equation through a split-operator Fourier-transform propagation of the molecular wavefunction in time, introducing some novel methods that increase computational efficiency. One can then calculate relevant experimental quantities such as excited state population and energy spectra.

12:00 p.m.
Tome 115
Lunch provided

Thursday, May 5th
New Majors Induction Ceremony & Picnic
Join us as we welcome and induct our newest members to the Physics Department!

4:30 p.m.
Tome 115 & Tome Backyard Area
Picnic food provided