Spring 2015 Physics Colloquium

Spin waves have been the focus of a great deal of research in quantum physics and solid state physics since the discovery of spin wave solutions to a magnetic lattice by Felix Bloch in the early 20th century.  In this thesis, we analyze a particular magnetic lattice from a theoretical standpoint.  In particular, we find the dispersion relation for spin waves in a two dimensional anisotropic lattice, and determine the stability of this solution with respect to modular perturbations.  This thesis aims to further establish the pathways and conditions under which spin wave solutions are unstable and lead to localized mode solutions, which appear to act more like solitons.Thursday, January 29th
Professor David Mertens, Dickinson College
"Phase Transitions and the Physics of Synchronization"

Spontaneous collective synchronization is a topic of great interest in the life sciences.  Although it may appear to be a nontraditional topic for physicists, our expertise in phase transitions gives us a unique perspective on the phenomenon. In this talk he will explain how the physics of phase transitions sheds light on synchronization and he will provide experimental and theoretical examples from his work on the topic.

12:00 p.m.
Tome 115
Lunch provided

Tuesday, February 17th
Professor David Reed, Dickinson College
RUSH Hour Speaker - "Round pegs, square holes and graduate school: Thoughts about how to succeed as an interdisciplinary scientist""

Professor Reed will focus on how to go from a liberal arts school, through graduate training and into early career while keeping an interdisciplinary view on the world since students often get confined to just one point-of-view on the world during their graduate studies. Some of his experiences will be used to highlight what can be achieved when you jump into a brand new field and what some of the costs are. Being able to look out at the natural world, ask questions and attempt to tackle them from multiple angles has more in common with Isaac Newton's self description as a "natural philosopher" than modern definitions of what a scientist is.

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

Thursday, February 19th
Seth Tracy '12 & James Doyle '12, Epic
"An Epic Approach to Digitizing Healthcare"

Join James Doyle '10 and Seth Tracy '12 in a discussion around how their Dickinson education and experiences helped uniquely place them at the junction of two growing fields: medicine and computer science. Learn how the complexities of electronic medical care are approached every day at Epic and what it means to impact over 180 million people with the code you write. The talk will also include an overview of career opportunities and time for open discussion.

12:00 p.m.
Tome 115
Lunch provided

Thursday, March 19th
Ritoban Basu Thakur, Fermilab Center for Particle Astrophysics, University of Illinois Urbana Champaign, Kavli Institute at the University of Chicago
"Dark Matter, matters more"

Over 80 years ago we discovered the presence of Dark Matter in our universe. Endeavors in astronomy and cosmology strongly indicate Dark Matter as an essential 27% of our universe. The Standard Model of Particle Physics does not provide any answers to the Dark Matter problem. Alongside other important factors, Dark Matter is responsible for formation of structure in our universe. The very construct in which we sit is defined by the abundance of Dark Matter, hence it is imperative that we understand its fundamental nature. This talk will cover several topics: physics, evidence and searches for dark matter. I will further outline the notion of "Big Science" that new experiments, such as dark matter searches are a major part of, thereby explaining the role of national labs such as Fermilab.   

12:00 p.m.
Tome 115
Lunch provided

Wednesday, March 25th
Dr. Amy Lytle, Franklin & Marshall
"Controlling Second Harmonic Generation with Counterpropagating Light"

Coherent light from laser sources can be converted from one color (or frequency) to another through a process called second harmonic generation (SHG). This is a nonlinear optical process based on the interaction of very intense light with transparent crystalline materials. SHG is essential to applications such as commercial laser development, high-contrast biological microscopy, and laser fusion ignition. Efficient conversion of light to its second harmonic frequency typically requires the use of highly engineered and in some cases, very costly nonlinear crystalline media. In this talk, I will describe the physics of nonlinear optics, the engineering challenges to making SHG efficient, and present latest results from my research group at F&M. We have been developing a way to probe and control the SHG process, not by engineering the nonlinear medium, but by engineering an interfering counterpropagating light field. This all-optical technique may potentially be used as a highly flexible method for improving efficiency, using any nonlinear medium, as well as a precise method of measuring dispersion characteristics. 

3:30 p.m.
Tome 115
Refreshments provided

Friday, April 3rd
Dr. Tarun Biswas, New Paltz, State University of New York
"Black Holes and Red Herrings"

For the last several decades, black holes have been a constant source of amazement for physicists as well as others. Many features of black holes are recognized to be counterintuitive. But the history of physics has taught us that "counterintuitive" does not always mean "incorrect". However, recent developments in the theory of black holes have cast significant doubts on their existence. It is to be noted that a black hole is, after all, a product of theory. Nonetheless, it produces some serious theoretical discrepancies. Here, he will discuss some of these discrepancies.

4:00 p.m.
Tome 115
Snacks provided

Thursday, April 16th
Dr. Desika Narayanan, Haverford College
"How to Form the Brightest Galaxies in the Universe"

Infrared Surveys have revealed large populations of incredibly luminous galaxies forming stars at rates ~1000x that of our own Milky Way.  In this talk, I will discuss what we know about these enigmatic systems observationally, as well as what we have learned after two decades of (frustratingly) trying to understand these galaxies in cosmological simulations.

12:00 p.m.
Tome 115
Lunch provided

Monday, April 20th
Physics Senior Talks
Nick Formus - "Getting to the End of Things"

We consider the general brachistochrone problem, which determines the quickest path between two points under some gravitational force.  Specifically, we examine both the “High Road/Low Road” and “Tri-Level” demos for balls rolling down different shaped hills.  For both demonstrations, one is to predict which path is the quickest.  A theoretical analysis using conservation of energy, the kinematic equations, and calculus of variations was used to predict the time differences between the different paths.  Those predictions were then experimentally verified using our newly built demonstrations.

Tyler Ralston - "Dependence of the Efficiency of a Gridded Solar Air Heater on the Mass Flow Rate"

A new design of a cost-effective, gridded solar air heater with a high solar to thermal energy conversion efficiency is presented, featuring an increased air to absorber interaction, while still allowing high mass flow rates. We investigate the dependence of this solar air heater’s conversion efficiency as a function of its mass flow rate and find that the efficiency significantly depends on it. Our investigation shows that the conversion efficiency of our solar air heater approaches 80% as the mass flow rate is increased to  . As the conversion efficiency depends linearly on the mass flow rate, a significant component of this investigation is the calibration of the anemometer. The findings of this research are based on data taken during both the winter and the summer seasons.

Ben Koltz - "Acquisition and Reduction of Astronomical Data in Python"

There are several existing programs, such as IRAF and MaximDL that facilitate the processes of taking and analyzing astronomy data. While these programs tend to fulfill their function well, they are not necessarily easy to work with and can require a significant amount of time to learn how to use. The goal of my project is to provide an alternative by writing programs for data acquisition and reduction with a focus on ease of use. Using the language python, I have written a few programs and compared their functionality with existing programs the department currently uses. I have found that my programs provide comparable functionality to their counterparts while being minimalistic in how much a user has to do, and therefore learn, to run the program.

Marie Holden - "756 Lilliana: An Astronomical Controversy"

756 Lilliana is an under observed asteroid main-belt asteroid. Of the relatively few studies done on 756 Lilliana, all have found contradictory results in regard to its light curve, rotation period, and shape. My project objective is to plot a light curve for 756 Lilliana and make a contribution in determining its rotation period. For my project, I observed this asteroid over the course of eight separate nights in October 2014 and January 2015 using the NURO 31-inch telescope in Flagstaff, Arizona. Using the data collected from the NURO telescope, I plotted my light curve with the assistance of IRAF, a data reduction software, and MPO Canopus, a program specially designed for photometry.

4:30 p.m.
Tome 115
Refreshments provided

Tuesday, April 21st
Physics Senior Talks
Marc Besson - "Stability and Intrinsic Localized Mode Formation on Ferromagnetic Lattices"

Spin waves have been the focus of a great deal of research in quantum physics and solid state physics since the discovery of spin wave solutions to a magnetic lattice by Felix Bloch in the early 20th century.  In this thesis, we analyze a particular magnetic lattice from a theoretical standpoint.  In particular, we find the dispersion relation for spin waves in a two dimensional anisotropic lattice, and determine the stability of this solution with respect to modular perturbations.  This thesis aims to further establish the pathways and conditions under which spin wave solutions are unstable and lead to localized mode solutions, which appear to act more like solitons.

Ben Kimock - "Nonlinear Modes and Topologically Stabilized Excitations in Ferromagnetic and Antiferromagnetic Sheets"

We present results generated by numerical simulations of 2-d ferromagnetic and antiferromagnetic lattices, which exhibit a variety of spin-wave phenomena. We have observed the formation of energy-localized patterns driven by an often-discounted magnetic field component known as the dipole or demagnetizing field, which depends on the macroscopic shape of the lattice. Each shape leads to very different kind of energy localization due to the way the demagnetizing field modifies the linear spin-wave dispersion relation. We have also investigated the stability of topologically protected excitations known as magnetic skyrmions in our lattices, and appear to have created a stable structure where current theory predicts one ought not to exist.

Devin Gaby and Robert MacKenna - "The Falling Chimney: An Analysis of the Internal Dynamics of a Rotating Structure"

When an industrial chimney falls, it will rotate downwards, leading to fractures at various points along the structure before it hits the ground. The goal of this research project was to gain a theoretical understanding of the internal dynamics of a rotating structure that can cause such breaks. After deriving the internal forces, torques and stresses that cause the chimney to fissure, we modeled the smokestack’s fall using toy models. Using wooden blocks and a separated aluminum cylinder, we created our own miniature chimneys. Our models did not agree with established theoretical results, raising interesting questions about material science.

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

Thursday, April 23th
Physics Senior Talks
Katie Roy and Andrew Chen - "Demonstrations in Ultrasound Imaging Concepts for Undergraduate Students"

Ultrasound Imaging is one of the most ubiquitous forms of sonography. It also ranks among the cheapest and safest forms of medical imaging techniques available. Ultrasound has a range of medical applications. It is gentle enough to image a developing fetus yet can be powerful enough to destroy a kidney stone. We have developed a series of demonstrations that isolate specific physics concepts in ultrasonography. We intend these demonstrations to be used as a learning aid for students who are studying the physics of medical imaging. These demonstrations cover the basics of ultrasound, the remote sensing capabilities of sound, and more advanced ultrasound theory.

Prasad Bommana and Raheem Chowdhury - "The Physics of Perpetual Motion Tops"

We demonstrate a “perpetual motion top” that uses a magnet embedded in a top, along with a hidden electronic circuit, to keep the top spinning “forever” (or at least until the battery dies).  The spinning top creates a changing magnetic flux in a wire coil beneath the platform.  The induced voltage in the coil activates a circuit that produces a magnetic field in the region the top is located.  This magnetic field provides a torque to the spinning top during part of its rotation, thereby keeping the top spinning.  We have constructed a large-scale version of the demonstration and measured the behavior of the circuit.

Michal Burgunder- "Chladni Figurers"

In the 17th century, a German physicist named Ernst Chladni discovered that one could visualize sound waves interacting via destructive and constructive interference by inducing transverse waves through a metallic material, and strewing a fine sand across it. Areas of constructive interference guide the sand to nodal lines, where destructive interference occurs, and the plate does not vibrate at all. In this research, a demonstration was designed to show this phenomenon for many different frequencies as well as derive equations that describe at which frequencies nodal patterns emerge from two different shapes of plate: a circular, and a square one. The figures for the circular plate are mostly concentric circles around the center, but the square plate exhibits figures of great multitude and complexity.

12:00 p.m.
Tome 115
Refreshments provided

Thursday, April 30th
New Physics Majors Induction Ceremony & BBQ

4:30 p.m.
Tome Hall Back Patio - Rain Location Tome 115
BBQ provided