Session B40: SPS Undergraduate Research and Outreach I

Summer 2007: My SPS intern experience and working with ComPADRE

For the summer of 2007 I was enrolled in the Society of Physics Students Internship program hosted by the American Institute of Physics in College Park, Maryland. My time at was spend working for the American Physical Society outreach department. My primary task was to expand and maintain Physicstogo.com which is part of the ComPADRE group of outreach websites funded by the National Science Foundation. More specifically, I searched for materials to add to the website, cataloged citation information, and updated the biweekly magazine portion of the website. Work experience was not the only thing gained from this internship. As a group of 8 interns we attended an event on Capitol Hill, met with members of congress, and toured nearly every monument and museum in the area. The 2007 SPS internship was an amazing opportunity and a summer memory that will remain with me for the rest of my life.   

Demonstrating Levitation and Suspension of a Superconductor on a Magnetic Track

The suspension and levitation of superconductors by permanent magnets is one of the most fascinating consequences of superconductivity, and a wonderful instrument for generating interest in low temperature physics. We present a novel classroom demonstration of the levitation/suspension of a superconductor over a magnetic track that maximizes levitation/suspension time, separation distance between the magnetic track and superconductor as well as insulator aesthetics. A theoretical explanation of the levitation/suspension and a simple mathematical model of the lateral restoring forces are discussed.   

Comprehensive study on deformation of metal samples based on measurements of temperature, in-plane displacement and stress-strain characteristics

We have studied the dynamics of deformation of metal samples. Our efforts are directed at finding some correlation between the stage of deformation (elastic, plastic, pre-fracturing stage, etc) and changes in properties of the sample such as the change in temperature across the surface, the stress strain characteristics, and the in-plain displacement on the sample surface. To study this, we simultaneously applied three independent data collection systems; a tensile machine to obtain the stress strain curve, an optical interferometer to study both the vertical and horizontal displacement of the surface, and two thermistors to obtain a continuous temperature reading as the sample deformed. With two thermistors, we were able to study how the temperature changed in different locations on the surface of the sample.   

Low-temperature calorimeter for magnetocaloric-effect measurements in high magnetic fields

The magnetocaloric effect, in which sweeping a magnetic field results in a temperature variation, is a powerful tool for detecting phase transitions in magnetic samples. The effect is particularly useful near the zero-temperature limit where a transition line becomes horizontal in the field-temperature phase diagram, a temperature region in which specific heat fails to exhibit sharp anomaly at the transition. At temperatures below 200 mK, however, eddy current heating produces a temperature background that becomes relative in magnitude to the temperature change of genuine features, seriously limiting sensitivity. This causes numerous problems in trying to extracting clear data. We describe a new calorimeter design which overcomes this problem in experiments using a dilution refrigerator in magnetic fields up to 20 T.   

Driven Intrinsic Localized Modes in a Coupled Pendulum Array.

Intrinsic localized modes (ILMs), also called discrete breathers, are directly generated via modulational instability in an array of coupled pendulums. These ILMs can be stabilized over a range of driver frequencies and amplitudes. They are characterized by a $\pi $-phase difference between their center and wings. At higher driver frequencies, these ILMs are observed to disintegrate via a pulsating instability, and the mechanism of this breather instability is investigated.   

Quartz tuning fork as a viscometer for Helium liquids

Oscillating beams serve as simple systems for measuring effects of energy dissipation as a result of interaction with their environment. Especially in miniature mechanical oscillators, the enhanced surface-to-volume ratio signifies the importance of damping caused by drag force. We have investigated the mechanical response of commercial miniature quartz tuning forks with a natural resonant frequency of 32.768 kHz. The changes in resonance frequency and damping have been measured at various Helium and Nitrogen gas pressures and various temperatures. Our results will be compared with theoretical predictions in order to extend its application to the sub-millikelvin temperature range as an effective thermometer in superfluid $^{3}$He.   

Demonstrating the Principle of an rf Paul Ion Trap

An rf ion trap uses a time-varying electric field to trap charged ions. This is useful in applications related to quantum computing and mass spectroscopy. There are several mechanical devices described in the literature which have attempted to provide illustrative demonstrations of the principle of rf ion traps, including a mechanically-rotating ``saddle trap'' and the vertically-driven, inverted pendulum$^{1,2}$. Neither demonstration, however, successfully demonstrates BOTH the sinusoidal variation in the electric potential of the rf trap AND the parametric stability of the ions in the trap described by Mathieu's equation. We have modified a design of a one-dimensional ponderomotive trap$^{3}$ so that it satisfies both criteria for demonstrating the principle of an rf Paul trap. Our studies indicate that trapping stability is highly sensitive to fluxuations in the driving frequency. Results from the demonstration apparatus constructed by the authors will be presented. $^{1}$ Rueckner, W., et al., ``Rotating saddle Paul trap,'' Am. J. Phys., 63 (2), February 1995. $^{2}$ Friedman, M.H., et al., ``The inverted pendulum: A mechanical analogue of a quadrupole mass filter,'' Am. J. Phys., 50 (10), October 1982. $^{3}$ Johnson, A.K. and Rabchuk, J.A., ``A One-Dimensional Ponderomotive Trap,'' ISAAPT 2007 spring meeting, WIU, March 30, 2007.   

Experimental characterization of piezoelectric THUNDER actuator shape

A new type of piezoelectric composite actuator called THUNDER, which was originally developed by NASA, has potential applications in micro robotics, aeronautics, acoustics and hydraulics. The manufacturing process produces internal stresses with accompanying structural deformation. It is the aim of this research to characterize these deformations. Detailed measurements were taken by a motion control LabView data acquisition system and measured with a laser micrometer on several different types of actuators. Several functional forms were used in an attempt to fit the data. The data was best fit by a circular segment function. We also used a transcendental equation to be able to compare to other single point published values. We found the range of dome heights to be between 10.15 mm and 1.45 mm. For one particular model, the manufacturing difference was found to be 16{\%} with an experimental error of 0.5{\%}. The robust experimental data is vital to the development of our finite elements models. Preliminary experimental results of voltage induced deformations will be presented.   

A Relativistic Understanding of Rotating Reference Frames

The purpose of this research is to obtain a greater understanding of relativistic acceleration and rotation. Particles in a rod experiencing constant acceleration have hyperbolic worldlines. A simple global rigid rotating frame cannot be physically realized, because the force needed to maintain an object in circular motion approaches infinity. This understanding will be discussed in this presentation.