 Physics
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Senior Projects |
| Physics Courses Faculty Research Events | 2002 |
Senior Projects of the Class of 2002
(updated March 15, 2002)
Kimberly Charlton with Eric Baer ( Macromolecular Sci.)
(Don Schuele - physics co-advisor)
Effect of Orientation on Structure-Property Relationships of PEBAX/PP Microlayered Films
The purpose of the project is to study the effects of orientation on the structure-property relationships of PEBAX/PP microlayered films. The films will be oriented using the Instron testing machine, and their structure will be studied using the optical microscope and x-ray diffraction techniques. In addition, the differential scanning calorimeter may be used to determine some physical properties of the films. The mechanical properties of the films after orientation will be studied using the tensile test, also done in the Instron. The goal will then be to draw connections between the changes in structure due to orientation and the changes in mechanical properties that result. To the degree that time permits, the effects of layer thickness and of sequential biaxial orientation will also be examined.
Chad Davis with Glenn Starkman
Higher Spin Wave Equations on Compact Hyperbolic Manifolds and Applications
Much attention has been paid recently to the possibility of extra dimensions, most of it in the context of "extra" flat toroidal factors to the space-time manifold; however, compact hyperbolic factors have recently been shown to possess attractive features. In order to understand the detailed phenomenological implications of these compact hyperbolic manifolds (CHMs) for phenomena as varied as super-symmetry breaking and the stabilizing effects of Casimir energy density, it will be necessary to compute the spectrum and wave-functions of excitations of fundamental fields in this geometry and with these boundary conditions. The challenge lies in the chaotic nature of dynamics on these manifolds which precludes most of the usual approaches. We will begin by constructing the wave operators for spin-0 and spin-1/2 fields in these backgrounds and investigating the properties of solutions, analytically and numerically where necessary, on the simplest CHM - the Poincaré octagon in 2d. We will attempt to generalize to more complex CHMs and to higher spin fields, and consider the implications to a variety of physical problems.
Anthony Hall with Robert Brown
Studies in Quantum Computing and Chaos
The parallel evolution of entangled quantum states is at the heart of quantum computation theory; the most renowned results are the exponentially improved efficiencies for finding hidden stabilizer subgroups (the RSA cryptosystem belongs to this class of problems). The potential power of quantum algorithms is largely unknown, however. It is thus of particular interest to find new regimes for quantum algorithms that provide computationally simple problems (since quantum computers are very much in their infancy) with non-trivial solutions.
A number of classical dynamic maps (e.g. the baker’s transformation, kicked rotator), which are simple in mathematical form, are in fact chaotic systems. Such systems (which are often intractable classically) exhibit precisely the combination desired for new quantum algorithms. We will be seeking classically chaotic mappings which lend themselves to 1) quantum operator representations, 2) simple quantum algorithms to describe the map, with a minimal number of qubits, and 3) exponentially more efficient implementations. Establishing correspondences between the quantized and classical dynamics is also likely.
Andrew Huss with Stephen Phillips (Electrical Engineering)
Integration of Sensor Technology for Mini-WHEGS Robot
WHEGS stands for wheels with legs. The mini-WHEGS robot is approximately the size of a pack of playing cards, and possesses great power and agility for its size. It can maneuver over or around almost any obstacle, and has potential applications as a research or surveillance tool. In order to be useful, however, it must contain a sensor package with control mechanisms that allow it to collect useful data and transmit or store the information effectively. Initially, I will explore the potential for including tactile sensation and video, audio, and infrared data acquisition. As my knowledge develops, I will attempt to create a working product based on these findings. A primary objective is to give the robot rudimentary knowledge of its orientation and location in relation to nearby obstacles. The next goal is for it to acquire reliable data of some kind. In both cases, new hardware must be integrated with the communications system, possibly a palm pilot. Due to space and weight constraints, I will take advantage of the control electronics that are present on the existing robot.
Peter Hyland with Dan Akerib
Characterization of a Cryogenic Detector to Improve Background Rejection
Based on our understanding of gravity, observations of the motion of stars and galaxies demonstrate a stronger gravitational force than can be accounted for by observable matter, i.e. matter that emits or absorbs light. Big Bang Nucleosynthesis suggests that the average density of baryonic matter, in units of critical density, is 0.05 ± 0.01. However, the total mass density, in units of critical density, WM, is 0.4 ± 0.1. Therefore another form of matter must be responsible for this “extra” gravity. One hypothetical type of dark matter, so called because it neither absorbs nor emits light, is a Weakly Interacting Massive Particle (WIMP). There are many different forms that a WIMP could take but particle physics provides specific candidates from Supersymmetry. These candidate particles have a mass range of 50 – 500 GeV and weak interaction cross sections.
CWRU is a member of the Cryogenic Dark Matter Search (CDMS), a collaboration of several institutions, which uses low temperature particle detectors that are sensitive to WIMPs and provide good background rejection. Since these detectors, which use novel technology, will soon be installed in the low-background experimental site, they have not been extensively operated under experimental conditions. It is known that the detectors have good sensitivity, but they have not been fully characterized. Over the next year, this senior project will characterize the response of a detector, guided by the needs at the experimental site to improve background rejection. Signals from photon, electron, and neutron sources are likely to be background signals and we will expose a detector to artificial sources of these particles.
Nathan Kaib with Chris Mihos (Astronomy)
The Study of Diffuse Intracluster Starlight
As galaxies move throughout clusters, they are subjected to the tidal forces due to the gravitational field of the cluster and gravitational forces called galaxy harassment stemming from close encounters with other cluster galaxies. Both of these effects tend to strip stars from the cluster galaxies, and over time a thinly spread population of intracluster stars accumulates. Evolutionary models for galaxy clusters can be made, and from these, simulated images can be produced. The structure and intensity of the intracluster starlight in the simulated images will then be characterized. The features of this light, from which predictions about the cluster age and baryonic to dark matter ratios can be made, will then be compared to the intracluster light of actual observed clusters.
Cameron Keenan with Lawrence Krauss
Halo
Signatures in Dark Matter Detection
Matter plays a crucial role in the nature of the universe. Features such as the expansion rate of the universe and the value of Einstein's Cosmological Constant are determined by the amount of matter present in the universe. If dark matter exists it will have a profound affect on physics. Up to this point no accurate measue of the local expansion rate of our galaxy has been recorded. It is our goal to measure this expansion rate and examine the affect that this value plays on the believed distribution of dark matter in the universe.
Joseph Khalil w. Guillermo Bozzolo (Ohio Aerospace Inst.)
(Gary Chottiner - Physics co-advisor)
Atomistic Modeling of the Co/Cu(111) Surface
Observed surface features of Co growth on the Cu (111) surface show promise in enhancing electron transport, increasing magnetic sensitivity, and growing quantum wires. Specific features include triangular-shaped islands with a height of two layers above the surface, decoration of the Cu step edges with mixed Co and Cu clusters, and monatomic deep pools of vacancies in the surface. These features, substantiated with detailed experimental evidence, raise questions on the driving mechanisms and how they could be altered to achieve specific properties or particular applications. In this project the BFS (Bozzolo-Ferrante-Smith) method for alloys, a quantum-approximate method particularly suited for large-scale atomistic simulations, will be applied to the Co system. Parameterization of the Co/Cu system using first-principles calculated data, analytical calculations, and large-scale Monte Carlo simulations will be performed in order to elucidate the characteristics of the system (i.e. formation of islands on the Cu surface, their composition, orientation, and depth). Results of these theoretical calculations will be compared to available experimental evidence, and atomistic driving forces for the studied features will be investigated.
Evan Large with Harsh Mathur
Models of Biological Evolution
Many complex natural systems are believed to evolve into a non-equilibrium critical state, following which the system experiences change through drastic non-gradual events. The original Darwinian view of biological evolution was that change happened gradually over the course of time. More recently, Gould and Eldridge have depicted biological evolution as periods of relative tranquility between occasional bursts of activity. The extinction of species can be seen as another self-organizing critical system, and can be modeled as such
In this project, biological evolution will be studied by a combination of numerical and analytical techniques and by analogy to models studied in statistical mechanics.
Aaron Manalaysay with Dan Akerib
Monte Carlo Simulation of a Neutron Rejection Technique in Dark Matter Detection
The Cryogenic Dark Matter Search (CDMS) attempts to detect dark matter in the form of Weakly Interacting Massive Particles, or WIMPs. The project uses low-temperature devices to detect these particles via scattering from nuclei. Such experiments involve considerable background events, and much effort is devoted to developing ways to discriminate WIMP scatters from other sources of particles. Most subatomic particles that reach the detectors are electrically charged, and thus interact with the electrons of the detectors. Electron recoils are easily identified and rejected. Charged particles can interact with nuclei as well, but the amount of energy deposited is below the threshold of the detectors. The most problematic background events come from neutron scatters. Both WIMPs and neutrons are electrically neutral, making them invisible to the electronic structure of the detectors; they both scatter primarily from atomic nuclei. Various techniques are used to identify neutrons, and reject them as background. However, before a method is put to use, particle-transport Monte Carlo simulations are utilized to determine the method’s effectiveness.
The second phase of CDMS will be conducted in a mine deep underground. The advantage of this is that the surrounding rock shields much of the cosmic rays that would otherwise shower the detectors with background events. However, there is a process of neutron production that is particularly difficult to reject. In this process, residual high-energy muons interact with the surrounding rock of the mine. The resulting “cascade” produces many different subatomic particles, including neutrons. The other subatomic particles produced carry electric charges, and rarely travel through the rock into the mine. A proposed method to reject these neutrons is to embed the surrounding rock with streamer tubes that can detect charged particles. If a nuclear recoil is seen in the detector that coincides with a signal in the streamer tubes, that event can be rejected. A simulation of this method must be performed to determine what percentage of these neutron cascades could be rejected.
Jason Radachy with Arnold Dahm
Directional diffusion of isotropic impurities in an hcp crystal of solid helium
At a certain temperature and pressure, 4He will crystallize in an hcp lattice. It has been seen that vacancies in a 4He lattice propagate as waves in straight lines along the planes of the crystal. Previous experiments to measure the parameters of these waves have reported significantly varying results. This project will measure the parameters of the vacancy waves by doping the solid 4He with 3He, which diffuses throughout the lattice by tunneling into vacancies. NMR techniques will be used to measure the diffusion rate in a sample of 4He after the spins have been saturated with a large RF pulse. The diffusion rate will be measured along three orthogonal axes in an effort to prove that the 3He is diffusing anisotropically.
George Ricco with Harsh Mathur
Network Models of the Quantum Hall Effect
The Hall effect occurs when charge carriers moving through a medium experience a deflection due to an applied magnetic field. This deflection results in a measurable potential difference across the side of the medium that is transverse to the magnetic field and the current direction. The Hall resistance is this new potential divided by the current created by the movement of the charge carriers. The Quantum Hall Effect is the quantization of the Hall resistance to values that depend only on fundamental constants over a range of magnetic field. The nature of the electronic wavefunctions at the transition between quantized levels is not fully understood. Existing theoretical models will be examined by numerical and analytical techniques. These include Anderson's model of a dirty "quantum wire" and Chalker's model of the quantum Hall effect.
Michael Salem with Tanmay Vachaspati
Stability of Oscillatory Solutions in Field Theory
The Standard Model of electroweak interactions permits a variety of non-topological solutions such as magnetic monopoles and Z-strings. It has been demonstrated that static Z-strings are unstable: if any were produced (in, say, a particle accelerator) they would decay rapidly. We will investigate the stability of oscillatory Z-strings.
A simple mechanical model that captures some key properties of the Z-string is that of a particle in a saddle-like potential. Although the static solution, that of the particle at rest on the “seat” of the saddle, is unstable (it rolls off), we have shown that oscillatory solutions exhibit bands of stability in the oscillatory amplitude parameter space. This mechanical system will be generalized to a classical field system, the so called ‘kink’ solution embedded in a U(1) theory. The properties of the mechanical and U(1) systems will be used for greater physical intuition in the determination of the stability of an oscillating Z-string in the more complicated electroweak theory.
William Sherwin with Robert Brown
Modeling Baseball Trajectories
Nothing is more celebrated in baseball than a long home run. The maximum distances of these home runs are often unknown, however, because they strike an object (such as a foul pole or the scoreboard). We propose constructing a model with which we can extrapolate accurately the partial trajectory visible to us via video recording. This model is to incorporate the Magnus spin force as well as the familiar drag and wind modeling, given an initial ball velocity (speed and direction) as determined from the video. We will investigate the uncertainties in the spin and its time dependence insofar as they can be determined by a fit to the trajectory data. From this work, we hope to be able to create a program usable by Major League teams and to satisfy our own curiosities by calculating the distances of some famous home runs.
Sharon Stefanovic with Lawrence Krauss & Cyrus Taylor
Information and Genetic Evolution
All genetic information necessary for reproduction is passed from generation to generation through DNA. Just how this information is processed during the DNA replication process is of vital interest in understanding the mechanics of genetic evolution of species.
We will attempt to explore how mutation rates are related to error coding, and how this relates to the sequencing of the human genome. The project may include the continuance of previous students’ work involving the dynamics of genetic drift.
The actual amount of unique information contained in a genetic sequence, and the entropy of that information, are of interest. As a first step, the compressibility of a sequence of data using a general zip algorithm asymptotically yields the amount of entropy in the sequence1.
1. Benedetto, Dario, Emanuele Caglioti, and Vittorio Loreto. “Language Trees and Zipping.” Physical Review Letters, V. 88, No. 4. 28 January 2002.
Jeffrey Steinberg with Corbin Covault
Moonlight Calibration of STACEE-64 Optical System
The Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) is an experiment designed to measure gamma ray sources ranging from 40GeV to 250GeV in energy from the universe via the interaction of the gamma rays with the atmosphere. These interactions result in Cherenkov light showers which can be detected with the STACEE apparatus. The STACEE apparatus consists of an array of 212 mirrors that reflect light to a tower which focuses the light onto a detector with only 64 of the 212 mirrors actually used in the experiment. We will perform a calibration of the end-to-end optical throughput of the STACEE gamma ray telescope experiment using the full moon as a light source. This calibration will be compared to the predictions given by Monte Carlo simulations, and it will involve the use of narrow band filters and photomultiplier tubes that will allow us to determine the throughput as a function of wavelength. The measurements determined in the moon calibration are directly related to the energy of the incoming gamma ray which determines the mean density of Cherenkov photons on the ground.
Jacob Yoder with Robert Brown
Novel Techniques in Magnetic Resonance Imaging
Two new approaches of MRI will be investigated. The first is a birdcage resonator that would allow simultaneous imaging over a wide area of sample. This result could be achieved by having the resonant modes converge at a single point. It is also hoped that this type of resonator will increase the signal to noise ratio of NMR images.
The second innovation to be investigated is the idea of MRI without use of a gradient coil. Traditionally, a gradient coil is used to pick out regions to be imaged by introducing a constant gradient in the primary B field. It may be possible to make images without a gradient coil by removing the condition of homogeneity from the primary field, i.e., allowing fringe effects.
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