Physics Department Seminar
Wednesdays 2:30 -3:30 pm in Frank 220

Schedule of talks

 

January 14

Don Smith Highlights from AAS

I will give a brief summary of some of the exciting results reported at last week's American Astronomical Society meeting in Los Angeles. Topics may include: first results from Fermi (GLAST), the Milky Way is bigger than we thought, adaptive optics images showing stars orbiting the galactic center, a supernova remnant expanding in real time, how to measure the spin of a black hole, and others...

January 21 Ryan Vary

Searching for long C-C bonds by Modeling the Graphite to Diamond sp2-sp3 Transition Mechanistically with ab initio Calculations and Plots Based on the Cambridge Structural Database. The interest in long C-C 'bonds' has increased through the study of carbon nanopore vacancies.  As potential molecular storage units, the chemistry of these long contacts has become increasingly important.  Through quantum mechanical single point calculations, a Potential Energy Surface is generated as a function of the C axis on the Graphite Unit Cell.  This PES as well as the potential surfaces of r, theta and Q are presented.  The methodologies and complications (e.g., hysteresis) that have resulted from this work will be introduced.  The mechanism of this transition, one that has before now never been understood, will be introduced as well as the direction of future calculations.

 

January 28 Melanie Corbett - The Hydrogen Spectrum. Using a monochronometer and a hydrogen lamp, we were able to measure a small band of wavelengths that represent the visible part of the hydrogen spectrum and compare our results to those predicted by the hydrogen model of Bohr.

February 4 Slide Rules, the Analog Mathematical Computer Ray Roseman, Collector, High Point, North Carolina.

Abstract. The slide rule is a mechanical analog mathematical computer which was used from the 1630’s through 1972. Mathematical advancement, particularly the development of logarithms and logarithmic scales made the slide rule possible. Mathematical advancement in conjunction with the development of programming and combined with electronic miniaturization resulted in the development of the hand held scientific calculator. The availability of the hand held scientific calculator made the slide rule obsolete overnight. The history, theory of operation, and use of the slide rule will be presented.

February 11 Don Smith Highlights from AAS II

I will give a brief summary of some of the exciting results reported at last week's American Astronomical Society meeting in Los Angeles. Topics may include: a supernova remnant expanding in real time, how to measure the spin of a black hole, and others...

February 18 Elise Weaver GUS practice talk

February 25 Discussion of GUS

March 4 Guilhem Ribeill NC State Nuclear Physics with Ultracold Neutrons

Ultracold neutrons (UCN) are free neutrons with energies of order 100 neV. Their low energies give them unique applications in both nuclear physics and solid state physics. They can be reflected down guides, trapped in stainless steel or magnetic bottles, and are significantly affected by gravitational potentials. In nuclear physics, their properties are currently being used to probe the limits of the standard model, while in condensed matter physics they offer the potential of being a powerful new tool to investigate the structure of matter. This talk will describe the production and use of UCN in a variety of scenarios, with a focus on nuclear physics applications such as the search for a neutron electric dipole moment. I will also describe our recent experiments to validate the use of solid oxygen as a high performance UCN source at the Lujan Neutron Scattering Center at Los Alamos National Laboratory.

March 11 No Seminar - Spring Break

March 18 Ryan Vary and David Jackman Tensor Talk We will talk about the mathematical construct known as the tensor and its applications in physics.  Conceptually, we will introduce the tensor through its relationship with established constructs (such as scalars and vectors) and present the tensor as a generalization of these constructs through a tensor property known as "rank".  Furthermore, we will consider the moment of inertia tensor and demonstrate that the relationship, L = Iw, "L" & "w" being the angular momentum and angular velocity, respectively, and "I" being the moment of inertia (specifically a scalar value), is in general not true.  Using the established ideas of the tensor, we will seek the general form of this relationship, L=I w.  Lastly, we will briefly explain the implications of this general form with a hands-on demonstration.

 

March 25 Melanie Corbett Mathematical Physics

April 1 Evan Faulkner-Hayes How Does Removing the Resonator from a Banjo Affect the Sound? A resonator is a thin, round piece of wood attached to the rear of a banjo. Removing the resonator from the back of a banjo affects the amplitudes of fundamental frequencies found in single notes. Without a resonator, the undertone frequencies of single notes have a higher amplitude and total power than that of the fundamental frequency.

Melanie Corbett Determining Planck's Constant with LEDs

April 8 NCUR Practice Talks

April 15 (NCUR)

Nathan Knisely Leaping  Leptons! Finding the Fundamental  Charge By balancing the forces on an  oil droplet in an electric field, I was able to find the fundamental charge of  the electron to be -(1.60 +/- .05) x10^-19 C.

 

Lopie Rhine The energy of a photon is its vibration in multiples of the constant h (Planck's Constant). I will be calculating h by making measurements of the Photoelectric Effect. By shining a light on a metal with photons vibrating at a high enough frequency to liberate the electrons on the metal, the energy of the photons will be transferred to the kinetic energy of the liberated electrons. By charging a cathode/anode photocell with these electrons and applying a potential difference between the pair, the stopping potential and thus the kinetic energy of the electrons may be found. By measuring this stopping potential for several known frequencies of light and performing a linear regression (the slope of which will be h/e where e is the charge of an electron), my Experimental Physics experiment will find the value of Planck's Constant.

 

April 22 LAST seminar – 2:00 p.m. Start

Kevin Muhanji Massing of electrons using Compton Scattering.

By using Cs-137 as my radioactive source, aluminum as my deflector and PHA my detector, I was able to determine the

shift in the Cs-137 peak and with the conservation of energy and momentum, I was able to find the fundamental

mass of the electron. 

 

Nathan Knisely Drag on Objects in Fluids

 

Brad Gould Expansion of the Universe

In my Mathematical Physics course, I created a MATLAB method to use the three Friedman equations and my Runge-Kutta method in order to model the velocity and acceleration of the Universe's radius from the Big Bang onwards. Taking the density, curvature, and radiation/matter dominance of the universe as parameters I was able to build a graph plotting the radius of the Universe vs. time. I found that in the radiation dominated era, R was proportional to t^{1/2}. In the matter dominated era, R was proportional to t^{2/3}. When both eras were plotted on top of each other, this graph was almost a complete match to one found in an undergraduate astrophysics text.

 

Brad Gould Determining the Speed of Light Using the Foucault Method

For my Experimental Physics II course, my task was to use an experimental setup proposed by Leon Foucault in 1862 which would determine the speed of light using a laser beam reflecting off a rotating mirror two times across a distance D. I found that the alignment of mirrors and lenses was both the hardest to perfectly accomplish and yet the most necessary to the ultimate success of my experiment.

 

David Jackman The Physics of Table Tennis

 

Abstract: One of the aspects of table tennis that makes it interesting to play is how the table tennis ball is able to move.  By hitting the ball hard, it slows down and by imparting spin on the ball, it can curve in midair.  We will talk about these phenomena and how they have been characterized as forces known as the drag force and the lift force.  Using these forces as our model for the movement of the table tennis ball, we will test this model and look at some of its consequences.

 

David Jackman How Newton Met Raphson: A Tutorial For Finding Zeros of Functions

Abstract: One of the best-known ways to find the zero(s) of a function is a computational method known as the "Newton-Raphson method."  We will derive the method, discuss its applications (including its pros and cons), and use it to find the zero(s) of various functions including the infamous Bessel function.

 

 

Announcements

Fall 2008