Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 9 of 9
Full-Text Articles in Entire DC Network
Electron Scattering Studies In The Framework Of The Symplectic Shell Model., Jutta Escher
Electron Scattering Studies In The Framework Of The Symplectic Shell Model., Jutta Escher
LSU Historical Dissertations and Theses
Electron scattering offers numerous advantages for studying nuclear structure: the weakness of the electromagnetic interaction, the precise knowledge of the reaction mechanism, the ability to vary independently the transferred momentum and energy, as well as the excellent spatial resolution that can be obtained with the point-like probing particles, have made this approach a valuable tool in nuclear physics. Scattering experiments provide crucial tests for the applicability and limitations of modern nuclear models and further our understanding of the nucleon-nucleon interaction and its modifications in nuclear matter. A microscopic theory for deformed nuclei, which takes proper account of the Exclusion Principle …
Nanoscale Structures And Fracture Processes In Advanced Ceramics: Million-Atom Md Simulations On Parallel Architectures., Andrey A. Omeltchenko
Nanoscale Structures And Fracture Processes In Advanced Ceramics: Million-Atom Md Simulations On Parallel Architectures., Andrey A. Omeltchenko
LSU Historical Dissertations and Theses
Properties and processes in silicon nitride and graphite are investigated using molecular-dynamics (MD) simulations. Scalable and portable multiresolution algorithms are developed and implemented on parallel architectures to simulate systems containing 10$\sp6$ atoms interacting via realistic potentials. Structural correlations, mechanical properties, and thermal transport are studied in microporous silicon nitride as a function of density. The formation of pores is observed when the density is reduced to 2.6 g/cc, and the percolation occurs at a density of 2.0 g/cc. The density variation of the thermal conductivity and the Young's modulus are well described by power laws with scaling exponents of 1.5 …
Atmospheric Neutrino Detection Using A Large Water Cerenkov Detector., Russell Clark
Atmospheric Neutrino Detection Using A Large Water Cerenkov Detector., Russell Clark
LSU Historical Dissertations and Theses
A 2.1 kton-yr exposure of data from the Irvine-Michigan-Brookhaven detector has yielded 72 atmospheric neutrino events with a vertex contained inside the fiducial volume and at least 0.95 GeV of visible Cerenkov energy. The ratio of muon-like events with respect to the total number of events was calculated for the data and the Monte Carlo simulation. The ratio of these two ratios $({muon-like\over total})\sb{Data}/ ({muon-like\over total})\sb{MC}$ was found to be $1.1\sbsp{-0.12}{+0.07}(stat.)\pm\ 0.11(syst.).$ The zenith angle dependence of this ratio of ratios is consistent with being flat. The region of $sin\sp2(2\theta) > 0.5$ and $\delta m\sp2\ > 9.8 \times 10\sp{-3} eV\sp2$ has been …
Photoemission Studies Of Magnetic Systems., Krishnan Subramanian
Photoemission Studies Of Magnetic Systems., Krishnan Subramanian
LSU Historical Dissertations and Theses
I have studied the electronic structure of thin films by photoelectron spectroscopy. My results show that even a monolayer film of Ni/Cu(001) exhibits bulk-like electronic structure and resembles that of bulk Ni. In order to better understand this result, I tracked the sp-band dimension at the Fermi surface of the Ni films for various coverages. For submonolayer coverages of Ni, the sp-band dimension was smaller than that of bulk Cu, but quickly reached that of bulk Ni by 1.2 ML Ni coverage. This continuous decrease implies a charge transfer from the Cu substrate to the Ni film, resulting in a …
Magnetic Measurements On Superconductors And Heavy Fermions., Donavan Weslee Hall
Magnetic Measurements On Superconductors And Heavy Fermions., Donavan Weslee Hall
LSU Historical Dissertations and Theses
Magnetization and de Haas - van Alphen (dHvA) measurements have been made on the high temperature superconductor Ba$\sb{0.6}$K$\sb{0.4}$BiO$\sb3$ and the heavy fermion CeB$\sb6$. First ever observations of the dHvA effect in Ba$\sb{0.6}$K$\sb{0.4}$BiO$\sb3$ are reported. Two dHvA spectrometers (pulsed field and field modulation) were used to measure two samples. Four frequencies are found in the field modulation data with the 11.6 kT orbit in good agreement with band structure calculations. The three lowest frequencies were measured with the pulsed field spectrometer. All dHvA measurements were made in the superconducting mixed state. These measurements indicate that Ba$\sb{0.6}$K$\sb{0.4}$BiO$\sb3$ has a Fermi surface. Magnetization …
Stabilization And Ionization Suppression In Intense Pulsed Fields., Vijay Saradhi Poduri
Stabilization And Ionization Suppression In Intense Pulsed Fields., Vijay Saradhi Poduri
LSU Historical Dissertations and Theses
The phenomenon of stabilization and ionization suppression in intense pulsed fields is investigated for systems initially in their ground states. This is done by considering one-dimensional model potentials which include one bound state and many bound states. The phenomenon of intense field stabilization is found to exist for both types of potentials while the pulse is on. However, it is discovered that this is not accompanied by suppression of ionization at the end of the pulse in all regimes of the peak field strength. The main features of the variation of the ionization probability with the peak field strength are: …
An Adiabatic Bond Charge Model For The Phonon Properties Of Ii-Vi Materials And Superlattices., Bhagwan Das Rajput
An Adiabatic Bond Charge Model For The Phonon Properties Of Ii-Vi Materials And Superlattices., Bhagwan Das Rajput
LSU Historical Dissertations and Theses
I present an extension of the adiabatic Bond Charge model to study lattice dynamics of highly polar II-VI semi-conductors and semi-metals and CdTe-HgTe superlattices grown along (001) and (111) directions. This is the first attempt to study phonons in CdTe-HgTe superlattices. My results for phonon dispersion, specific heat and elastic constants for the six bulk materials are in good agreement with experimental observations. The best parameter sets for the six compounds show trends that are consistent with the parameters for group IV elemental semi-conductors and III-V compounds. For CdTe-HgTe superlattices, I find that the long range Coulomb interaction between particles …
Data Analysis Of The Allegro Gravitational Wave Detector., Evan Mauceli
Data Analysis Of The Allegro Gravitational Wave Detector., Evan Mauceli
LSU Historical Dissertations and Theses
The Allegro gravitational wave detector has been operational from 1991-1994, and 1996-present. We present a detailed description of the detector and the data acquisition system. Two distinct types of data analysis are detailed. First, we describe the search for burst sources of gravitational radiation. These are impulse forces acting on the bar, presumably from the stellar collapse associated with supernovae. Construction of the optimal filter for burst signals is described, as well as its application to the data from the detector. The uncertainties introduced into timing and signal strength estimates due to stationary noise are measured, giving the windows for …
Radio-Frequency Impedance Measurements On Thin Films Of Yttrium Barium Copper Oxide., Vibha K. Pant
Radio-Frequency Impedance Measurements On Thin Films Of Yttrium Barium Copper Oxide., Vibha K. Pant
LSU Historical Dissertations and Theses
The Kosterlitz-Thouless phase transition in epitaxial films of YBCO of varying thickness is studied. The phase transition is found to occur in these films in both zero fields and in perpendicular and parallel magnetic fields up to 0.5 T. In addition, the same transition is seen in a lead film of thickness less than the penetration depth in lead. This measurement is used as a calibration to determine the penetration depth in YBCO for both the zero-field case and perpendicular-field case. Once the penetration depth is determined, the effective thickness of the superconducting layer is calculated for all the films. …