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An investigation of the ray and diffraction optics of the pinhole camera. Characteristics and measures of performance will be tested against a camera of your own design. |
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Crawford |
X-ray Diffraction |
Students will exploit the wave nature of x-rays (Bragg Diffraction) to measure the lattice spacing of different crystals. Students will also gain a working knowledge of the production of x-rays from an electron beam, and use the measured characteristic bremsstrahlung spectrum to determine Plank's constant. |
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Good |
Plasmas |
Plasmas, or ionized gases, constitute 95% of the matter in the universe, but are rare in terrestrial settings except in a variety of man-made applications ranging from fluorescent lightbulbs to arc welders, from material processing to thermonuclear fusion reactors. In order to study behavior of plasmas, many diverse diagnostic methods have been employed. Two methods to be investigated in the projects that I am offering this semester utilize electrostatic Langmuir probes, and laser optogalvanic spectroscopy. The student may choose between these two projects. I. An electrostatic Langmuir probe is simply a conductor inserted into a plasma that is biased at variable voltages in order to collect charged particles, i.e. electrons and ions. An analysis of current/voltage (I/V) characteristic curves yields several fundamental plasma parameters including ion and electron densities, electron temperature, and the ionization energy of the gaseous atom. The goal of this project is to gain experience with a Langmuir probe, gathering and analyzing several I/V characteristics under varying operating conditions of an argon plasma in a transistor tube, and in the Pickets Charged Plasma Device. Although close supervision is provided to help the student understand the plasma-probe model and perform the analysis, this project allows the student to work very independently, setting her own schedule for experimental work and analysis. 2. Laser optogalvanic spectroscopy (LOGS) is a method to study atomic or ionic species found in a plasma discharge. Resonant absorption of laser light results in a change in discharge current that is easily detected. The topic to be investigated in this project will vary from one student to another, but will include analysis of the mechanism of the optogalvanic effect, the Zeeman effect in Sodium gas, and hyperfine splitting in Niobium. In this project the student will work closely with the instructor, who will provide technical laser support. Due to the collaborative nature, we must find suitable meeting times for the experiment, with both schedules restricting the choices. Two full afternoons each week will be necessary for adequate progress. In the last session the student will be working more on his own. The goal of this project is to introduce the student to lasers and laser spectroscopy, while at the same time learning something about plasmas and atomic structure. |
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Hayden
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Radio Astronomy
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Two Choices: 1) Measurement of the Galactic Rotation Curve Using the 21 cm Hydrogen Line 2) A Two-Dimensional Survey of the Apparent Angular Extent of the Milky Way as Determined by Analysis of the Neutral Hydrogen Line. |
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or Astrometry of Asteroids |
Using the College 16" telescope and a large-format CCD camera, students will obtain the light curve of a variable star, or will find and measure the positions of several asteroids. An advanced project is available as well for those with more experience. |
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Pella |
Adventures in Mossbauer Spectroscopy or Neutron Activation
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Neutron
Activation
Students will use the neutron howitzer to produce radioactive isotopes and determine their half-lives. In addition you will determine the ratio of the thermal neutron flux, to the fast neutron flux for the Pu-Be source. Mossbauer Students will continue Mossbauer adventures started in PH 310, measuring isomer shifts, hyperfine spectra, and the effects of quadrupole splitting for various unknown samples. |
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Electron Spin Resonance Techniques
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Electron spin resonance (ESR) is a technique similar in practice
to nuclear magnetic resonance (NMR). In NMR, nucleons or entire nuclei
respond to an external magnetic field. With ESR, atomic electrons respond
to an external magnetic field. ESR is most informative when studying materials
that have unpaired electrons. For a set of samples, we will measure the
difference between energy states for electrons whose magnetic moments are
either aligned parallel or antiparallel to some external magnetic field.
The energy difference can be expressed in terms of some frequency, and if
an alternating magnetic field is introduced at that same frequency, resonance
occurs. |