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Ann Birenbaum Modern Physics and the Nazi Regime
Corbin Brace Teaching methods in high-school physics
Joshua Carey Spectroscopy of the 3p-3d transition in sodium
Francisco Galvan Spectroscopy and Photometry of a Very Faint TOAD
Jeremy Greenfield The physics of baseball
Benjamin Heneveld Atomic force microscopy of the water-ice interface
Ryan Jennerich Measuring the temperature of ultracold atoms in a magneto-optical trap
Witold Lipski Counter-intuitive pulse schemes in quantum mechanics
Aubry Love Genetic algorithms for use in feedback coherent control
Daniel Morris Applications of pulse-shaping in coherent control
Mark Oleszek The H.A.A.R.P. project
Jason Phinney Temperature dependence of electron mobilities in organic semiconductors
Jessica Porter Langmuir-Blodgett films of gold nanoclusters
William Sanford Improving astrophysics at Colby College
John-Paul Thompson Temperature dependence of electron mobilities in organic semiconductors
Emily Zlatin Spectroscopy of the 3p-3d transition in sodium

Catherine Garland -- Mid-Infrared Analysis of the Star Formation G34.26+0.15, Advisor: Professor Campbell

Catherine is studying G34.26+0.15, a famous Ultra Compact HII (ionized hydrogen) region in which stars have just formed inside a dusty cloud. The stars are not optically visible because the dust surrounding them absorbs all radiation and reradiates it at longer wavelengths. Observations in the mid-infrared actually image the surrounding dust and provide a way to probe this region. G34 has been well studied at radio wavelengths, but because of the difficulties associated with observing in the infrared, Catherine's study is the first time it has been well imaged in the mid-infrared. The data being analyzed were acquired using a prototype instrument, MIRAC II (Mid-Infrared Array Camera), by Prof. Murray Campbell and collaborators at the Infrared Telescope Facility on Mauna Kea, Hawaii in 1995. As part of this project, new techniques are being developed for processing, reducing, and analyzing the data using a UNIX workstation. These include modeling techniques to set upper and lower limits on properties of the region, such as column density of dust and stellar luminosity. The results of this study provide further insight into the process of star formation and the conditions present in G34.

Frank Struwe -- Interaction Free Measurement, Advisor: Professor Conover

Frankšs research project involves interaction free measurement using a quantum optical system. This scheme is designed to detect the presence of an object using photon interference in an interferometer without the photon ever hitting the object. Traditionally this is done using a single photon from a down conversion crystal, but here a classical source is used from a pulsed diode laser. The system is set up such that incident photons entering into the interferometer exit the interferometer with a destructive interference fringe focused on a photon counter. However, an object placed in one arm of the interferometer collapses the wave function in that arm and subsequently there is no longer destructive interference at the beam splitter hence photons will be detected by the photon counter. By using a separate photon counter as the object an accurate count of the photons absorbed and exiting the interferometer can be obtained. Since photons do indeed exit the interferometer they could not have been absorbed, and the object was detected by nearly interaction free measurement. Various methods and experimental techniques can increase the efficiency of this scheme which Frank will explore.

John Evans -- Time-of-Flight Mobility Measurements in Thin Films of Pentacene, Advisor: Professor Nelson

Organic thin-film semiconductors are of great interest in flexible, low-cost electronic applications. Numerous organic materials have been analyzed, but one of the most promising is pentacene, a polycyclic aromatic hydrocarbon. The field-effect mobility of charge carriers in organic materials is frequently too low for feasible use, but pentacene has exhibited hole drift mobility comparable to that of a-Si:H. However, these mobility values were extracted from transistor characteristics, and have proven to be inconsistent from device to device. A more direct method, the time-of-flight technique, will be applied by John in an attempt to more decisively characterize the hole mobility of pentacene.

Penjani Mphepo -- Seeback Effect & Electricity Power Generation, Advisor: Professor Nelson

Penjani is researching the properties of a few common metals and alloys, in particular their Seeback coefficients. He is also building a solid state thermoelectricity power generator that should be able to harness heat energy into electrical energy. The goal of this project is to learn how to make a generator that operates using solar heat, which is easy to build and which uses affordable materials ( e.g., iron, constantan, copper ). The intention is for this to be a viable electrical power source in developing countries.

Eamon Briggs -- Design of a High-Temperature Hall Measurement System, Advisor: Professor Nelson

Silicon doped with erbium and oxygen has been shown to be optically active, emitting visible light. Such a chip has importance in engineering due to the possibilities of designing computer hardware based on optical signals. Prof. Nelson has conducted experiments to measure the charge carrier density as a function of temperature for various chip annealing processes. Such data cover the temperature range of 4K to 180K. Eamon will be designing and building a high temperature system to perform Hall measurements in the range of 100K to 475K. This will be used to compare the high temperature dependence of the charge density of erbium- and oxygen-doped silicon annealed in three different manners.

Jason Stauth -- High-Temperature Hall Measurements of Erbium- Doped Silcone, Advisor: Professor Nelson

Jason is designing a controlled heating unit to take erbium-doped silicone samples to temperatures up to 200C in an oxygen depleted environment. Once the heating unit is completed, Hall measurements of the doped samples will be taken in the high temperature range. Photo-lithography will be performed on some of the samples to provide electrical contacts in the doped regions.

Colleen Schwartz -- Analysis of Outflow Geometry in a High Mass Star Formation Region, Advisor: Professor Campbell

The Orion BN/KL Region is an archetype in high mass star formation. Colleen has participated in the reduction and analysis of Very Long Baseline Interferometry data of the silicon monoxide (SiO) and water maser emission surrounding the radio source I in this region. Traditionally, this emission was hypothesized to lie in a rotating, expanding disk about the source, but through this project, Colleen and her collaborators at the Harvard-Smithsonian Center for Astrophysics have shown that this is incorrect. The SiO maser distribution traces a bipolar conical shape, while the water masers lie approximately perpendicular to the SiO. For her thesis Colleen is working with Prof. Campbell, studying the astrophysical mechanisms which produce maser emission, and analyzing the geometry of the system.

Ali Mian -- Comparing Lamb Shifts in Hydrogen and Antihydrogen and Testing CPT Symmetry, Advisor: Professor Bluhm

Experiments at Fermilab will be measuring the 2s-2p Lamb shift in relativistic beams of antihydrogen. A comparison of the Lamb shift in antihydrogen and hydrogen will provide a new test of CPT. The symmetry transformation CPT involves the combined operations of charge conjugation C, parity reflection P, and time reversal T. A fundamental theorem in quantum field theory states that all local relativistic field theories of point particles are invariant under CPT. However, in string theory the CPT theorem may not apply since strings are extended objects. Ali will be performing calculations that analyze the experiments at Fermilab. He will be calculating the Stark eigenstates that are produced in the experiment and studying their interference behavior. The goal of the project is to determine the sensitivity of different types of CPT violation that could arise in a more fundamental theory, such as string theory.

Greg Foltz -- Experiments with Rubidium Atoms in a Magneto- Optical Trap, Advisor: Professor Tate

Recently, an atom trap was constructed at Colby which uses diode lasers and an inhomogeneous magnetic field to confine rubidium atoms to a small region of space. A single diode laser beam is split into three beams, and each intersects perpendicularly with the others inside a vacuum chamber. Anti-Helmholz coils are arranged such that the magnetic field in the overlapping region is approximately zero. The lasers are tuned slightly below the absorption frequency. In the presence of the applied magnetic field, the energy levels of the rubidium atom are split according to the Zeeman effect. With correct polarization of the beams, certain transitions are selected. In each case, due to the linearly varying nature of the applied magnetic field, the transition frequencies decrease linearly from the center of the trap. With a laser tuned slightly below the normal (no external magnetic field) transition, atoms are cooled as they approach the center of the trap. The resulting population of slowly moving rubidium atoms is viewed with a CCD camera. Greg's research involves implementing a larger trap and making measurements of the trapped atoms, such as the number trapped and the average lifetime of atoms in the trap. Both measurements are performed with photodiodes. A variety of other measurements, such as the temperature of the trapped atoms and the spring constant of the trap, are also possible.

Phil Boone -- Spectroscopy of Cesium Atoms Using an External Cavity Diode Laser, Advisor: Professor Tate

Phil is setting up an external cavity diode laser and using it to look at the hyperfine energy level splitting of Cesium atoms. One of the useful properties of an external cavity diode laser is that it has a piezo-electric crystal behind the mirror in the external cavity. By changing the voltage on the crystal (thereby causing the crystal to change shape, which causes a minute shift in position of the rear defraction mirror) Phil will be able to sweep the frequency of the laser over a set range, allowing him to fully examine the energy level splittings.

Peter Shapiro -- Field Ionization of Potassium Rydberg States Using Strong Electric Fields., Advisor: Professor Conover

Peter is using lasers and high voltage pulses with variable rise times to study the ionization of potassium Rydberg atoms. Rydberg atoms are formed by exciting the outer electron to a very high principle quantum number, n. The atom is then subjected to an electric field pulse which is strong compared to the binding electric field between the nucleus and the outermost electron. This electric field pulls the electron off of the atom. Two pulse rise times will be looked at: those of about 1 microsecond, which have been previously studied, and those of about 10 nanoseconds which have not.

Bryan Cunitz -- Mode-Locking a Diode Laser to Generate Picosecond Light Pulses, Advisor: Professor Conover

By mode-locking a diode laser, it is possible to generate a high intensity, short pulse (on the order of picoseconds) of laser light. The method of mode-locking that Bryan is using involves coupling an RF signal with the laser's power supply. An external cavity will be set with a length so that the round trip time of a photon from the laser is the period of the RF signal. The first part of the project involves setting up and optimizing the external cavity and RF signal. Bryan will also study the theoretical background of the mode- locking. The second part involves measuring the pulse time. Since the pulse is so fast, it cannot be measured using an oscilloscope and therefore it is necessary to construct an auto-correlator. Once the laser has been completed, it will be used for conducting experiments on lithium atoms.

Catherine Smith -- Alternative Automotive Fuels and Their Use with Fuel Cell Vehicles, Independent project at Dartmouth College

Catherine has been working on an independent project at Dartmouth College investigating the use of alternative fuels in fuel- cell vehicles. This project follows up on a previous project she did which focused on hydrogen and its use in fuel cell vehicles. Catherine has been working with a group of engineers, who are developing improved methods for using methanol and ethanol in fuel cells. In particular, Catherine has been looking for ways to determine how to evaluate the most important aspects of alternative fuels. She has built a template to allow a standard comparison of the results from the ethanol and methanol models. Catherine is also exploring some of the environmental issues concerning fuel cells as well as recent advances in the design of fuel-cell vehicles.

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