Summer 2001 Symposium Abstracts

Penning Ionization of CO by HE^*
Larissa Bifano
advisor: Dr. Peter Siska
Following in the footsteps of previous Penning ionization beamists, this experiment can aid in the understanding of the mechanics and dynamics of the recation He^* + CO --> CO⁺ + e^-. An angular distribution and lab angle energy analysis of the product ions is performed at 2.72 and 4.0 kcal/mol. The CO⁺, like its predecessor N₂⁺, is predominantly forward scattered, with evidence of backscattering as well. The collision complex is assumed to be short lived, another similarity to the N₂⁺. Through further analysis of the energy data and quantum mechanical modeling, it is hoped that a more thorough comparison can be made of this asymmetrically charged and massed system to previous systems, especially N₂⁺.

Calibration and Gain Measurements of MINOS Beam Ionization Chambers
Darius Dixon
advisor: Dr. Donna Naples
The goal of the MINOS project is to generate a beam of a specific type of neutrino with the intent to determine whether or not neutrinos have mass. At the University of Pittsburgh, we will continue to analyze the MINOS monitoring detector's test beam data generated at BNL. This data will be used to calibrate the prototype PAD Ionization Chamber (PIC) so that we will have a better understanding of how the actual full-sized PICs will operate under a less controlled environment. We are tracking the dependence of the gain on time using a fixed radioactive source to project charged particles through the prototype ionization chamber. We will also study the SWIC readout electronics that are vital to the construction of the data stream from the detector so that the readings can be integrated over a specific readout time.

The Development of an Omni Directional Sound Source
Kaisha L. Fields
advisor: Dr. Oladipo Onipede
The objective of this project is to create a dodecahedral sound source, allowing sound waves to radiate centrally outward. The structure of the polyhedron allows twelve speakers to be mounted, which will emit sound in unison. Constructing the device involves knowledge of composite materials, their acoustic properties, and series and parallel circuits, along with basic geometry. Schematics and mathematical/linear-algebraic software such as Matlab will be used to obtain optimal construction so that the device operates at a 4 ohm impedance. Sound intensity will be verified by measuring intensity at various faces and integrating over the whole solid. High precision is desired since the completed device will be used as a standard to test other equipment.

QSO Absorption-line Systems
Eric Furst
Astrophysics Group
Quasi-stellar objects (QSOs) are the most distant and intrinsically luminous objects in the known Universe. Because of their extreme distance and luminosity, they can be used to probe intervening gaseous material. This gas can be studied by analyzing the way in which it absorbs the light from the QSOs' spectra. Information about the redshift, and by extension, distance, as well as the nature of the intervening matter can be gathered through detailed analysis of these spectra. The goal of this research is to find and catalog damped lyman-alpha, Mg-II, and broad absortion lines (BALs) in the spectra of ~3000 QSOs that were collected in the Sloan Digital Sky Survey (SDSS). An automated search algorithm is being developed for this purpose.

Kyoo Jackson
advisor: Mike Gach
A simple computer-based hemodynamic model of arterial blood supply will be developed to understand blood transit time from left ventricle to critical organs (specifically brain and kidney). Blood flow rate is critical to quantifying organ perfusion and to identify cardiovascular disease. Literature on blood flow velocities and arterial distances and diameters may be lacking, so an MRI scan will be used to map the arteries and find approximate lengths and diameters. Three dimensional models, MR angio scans, and CT angio scans of abdominal, thoracic, and cranial vessels may be used for length measurements and in vivo velocity calculations. Computer simulations will then be constructed, using approprate assumptions of pulsate plug flow and arterial velocity waveform. A flow phantom will be constructed to simulate blood flow, and the resulting data will be compared against mathematical flow models.

Turbulent Colloidal Crystallization in Two Dimensional Free-Standing Film
Lena Katz
advisor: Dr. Xiao-Lun Wu
The cyrstallization of polystyrene microspheres in sopa films is well understood. Less clearly understood is turbulence's effect on the crystallization. This experiment uses electromagnetic convection to cause turbulent flow, and studies the effects of this flow on two-dimensional crystallization.

Finite Element Modeling of EM Field Effects on Bone Cells
Ron Moore
advisor: Dr. Dipo Onipede
This project will attempt to map the effects of electromagnetic fields on human bone cells. EM fields may be useful in healing of bone fractures and possible preventative treatment. Thorough literature search will concentrate on possible underlying mechanisms, as well as overall properties of biological tissue. Finite element software will be used to model the phenomena.

Polymer-Strengthened 2D Colloidal Crystals
An T. Ngo
advisor: Dr. Xiao-Lun Wu
The unique properties of colloidal crystals suggest applications as components in optical networks. A variety of techniques have been employed to induce self-assembly of latex microparticles into ordered arrays. Our experiment focuses on creation and analysis of highly ordered, millimeter-diameter two-dimensional colloidal crystals. We seek to improve crystal durability by embedding the structures within an acrylamide hydrogel. The crystals are produced in a vertical freestanding film consisting of micoparticles, monomer, initiator, surfactant, and water. Application of audio vibrations during pulling causes the migration of grain boundaries, resulting in long-range order. Based on previous studies of three-dimensional colloidal crystals, we expect the UV-initiated polymerization will allow the crystals to better withstand mechanical disturbances and ionic impurities.

Penning Ionization of Methane and Excited Helium
Jill Schmidt
adivsor: Dr. Peter Siska
Penning ionization occurs when a molecule collides with a metastable atom having an excitation energy much larger than the lowest ionization potential of the molecule. This summer, a cross molecular beam chamber under high vacuum pressure will be used to study the Penning ionization reaction of methane and excited helium. This experiment will undertake novel analyses, including analysis of relative cross section, product angle distribution, energy analysis, and energy distribution. We seek to reveal collision dynamics and interaction forces, and determine influences of kenetic energy. These analyses will aid in understanding electronic structure and catalysis of chemical vapor deposition on new surfaces, in particular diamond films.

Utilizing Quasar Absorption Lines to Study the Evolution of Neutral Hydrogen in the Universe
Charlotte Sotomayor
Astrophysics Group
Quasars are the most luminous and distant objects in the universe. A quasar thus acts as a powerful probe for intervening gaseous material. This is crucial in revealing the nature and evolution of galaxies from their formation to their current state. The damped Lyman alpha absorption line systems seen in quasar spectra are due to 95% of the neutral hydrogen observed in the high and low redshift universe. The fifteen year old paradigm suggesting these lines are caused by spiral galaxies is now being refuted. Low redshift studies are revealing that the lines are casued by a mixture of galaxy types, including spiral, dwarf, and low surface brightness. Our objective is to identify the galaxies responsible for the damped Lyman alpha absorption lines in the spectra of nine quasars.