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Ground-Level Atmospheric Neutron Flux Measurements In The 10-170 Mev Range, Renu Saxena
Ground-Level Atmospheric Neutron Flux Measurements In The 10-170 Mev Range, Renu Saxena
Doctoral Dissertations
We report the results of ground level neutron measurements in the energy range of 10-170 MeV by the neutron double scatter telescope developed at the University of New Hampshire. Measurements were carried out at different altitudes and latitudes for the first time using the same telescope, yielding better correction values for comparison of fluxes measured at different altitudes and latitudes. The measurements were performed at four different locations in the U.S.A.: Leadville (3.1 km) and Boulder (1.66 km), Colorado in the rigidity range of 2.97 to 2.90 GV; Mt. Washington (1.85 km) and Durham (24 m), New Hampshire in the …
Study Of Doubly Excited Ridge States Of Atoms., Quintin Ricardo Molina
Study Of Doubly Excited Ridge States Of Atoms., Quintin Ricardo Molina
LSU Historical Dissertations and Theses
In this dissertation on the structure and properties of doubly excited state of atoms, we are interested in states of atoms where two electrons are highly and comparably excited. Such states have been named doubly excited ridge states. Angular and radial correlations of two electrons in such states are of interest. First a semi-empirical study, based on available data, is carried out to test the validity of a pair quantum number descriptions in which a single six-dimensional Rydberg formula is proposed to organize sequences of doubly excited states as a function of energy. Next, we make a detailed analysis of …
Sensitive Cryogenic Transducer Development And Analysis For Use On Gravity Wave Detectors., Norbert Daniel Solomonson
Sensitive Cryogenic Transducer Development And Analysis For Use On Gravity Wave Detectors., Norbert Daniel Solomonson
LSU Historical Dissertations and Theses
The design and development of an improved superconducting inductively modulated transducer is discussed. The transducer is designed to optimize the performance of a 2-mode, resonant bar, gravitational wave antenna. A detailed theoretical analysis which includes all relevant noise sources is described. Conditions for optimizing 2-mode detector performance are derived and design curves are presented. Based on the results of this analysis, an optimal transducer has been designed for use on the LSU gravitational wave detector. The fabrication and testing of several optimal mass 400gm transducer resonators is described. The effects of low temperature annealing on the mechanical Qs of the …
Neutral Impurity Scattering In Semiconductors., Kwok Chuen Kwong
Neutral Impurity Scattering In Semiconductors., Kwok Chuen Kwong
LSU Historical Dissertations and Theses
Neutral impurity scattering is a relatively untouched subject because it is only significant at very low temperatures. With the development of a new class of impurity band conduction devices that operate at cryogenic temperatures, it becomes necessary to describe the scattering in a more realistic fashion. We have calculated both elastic and inelastic scattering of electrons by substitional As in n-type Si, taking into account the anisotropy of the host band structure. Specifically, in regard to inelastic scattering, we calculated the differential and integrated cross sections for transitions from the ground state to the valley-orbit split states $\Gamma\sb{15}$ and $\Gamma\sb{12}$. …
Theoretical Description Of Doubly Excited States Of Molecular Hydrogen., Byungduk Yoo
Theoretical Description Of Doubly Excited States Of Molecular Hydrogen., Byungduk Yoo
LSU Historical Dissertations and Theses
The present study focusses on presenting a global picture to theoretically describe the singly- and doubly-excited states of molecular hydrogen. The non-iterative eigenchannel R-matrix method and multichannel quantum defect theory have been combined for understanding the physics of the wide range of energy and internuclear distances in a unified manner. In this dissertation ab initio calculations for $\sp{1}\Sigma\sb{g}$, $\sp3\Sigma\sb{g}$, $\sp1\Sigma\sb{u}$ and $\sp3\Sigma\sb{u}$ symmetries of hydrogen molecule are performed to test the present approach. The body-frame quantum defects are expected to be mild on energy, but found to be strongly dependent on both energy and internuclear distances in this problem. The …
Parametric Motion Transducer For Gravitational Wave Detectors., Odylio Denys De Aguiar
Parametric Motion Transducer For Gravitational Wave Detectors., Odylio Denys De Aguiar
LSU Historical Dissertations and Theses
We designed, constructed, and tested (using two different low phase noise electrical pump generators) a cryogenic double-resonant parabridge motion transducer made out of niobium, whose electrical output was amplified by a two stage MESFET cryogenic amplifier. Most of the experimental results agreed well with the theoretical models, and we successfully measured the mechanical Brownian motion of this transducer. We were able to adjust the two electrical bridge resonant frequencies on top of each other at the pump frequency, allowing us to obtain an electromechanical coupling as high as 0.054. This high coupling, corresponding to an rms electric field strength of …
Very Highly Excited States Of Two-Electron Systems., Hossein Roshani Sadeghpour
Very Highly Excited States Of Two-Electron Systems., Hossein Roshani Sadeghpour
LSU Historical Dissertations and Theses
The delicate balance that exists between the forces mediating the interaction within multiply-excited electrons and the binding forces of these electrons to the nucleus is totally ignored in the independent particle model of electronic interactions. This dynamical "see-saw" is best described in the hyperspherical representation. We use this method to obtain hyperspherical potential curves, analogous to the Born-Oppenheimer curves of molecular species, for very highly-excited two-electron states of the hydrogen negative ion, helium, and calcium. The present numerical effort exploits the analytic nature of the solutions to the Schroedinger equation at small and large distances to diagonalize the hyperspherical Hamiltonian …
Observations Of Cosmic Gamma Ray Sources And Their Contribution To The Diffuse Gamma Ray Background, Debadarshi Bhattacharya
Observations Of Cosmic Gamma Ray Sources And Their Contribution To The Diffuse Gamma Ray Background, Debadarshi Bhattacharya
Doctoral Dissertations
The objective of this project is to study soft $\gamma$-ray emission in the (0.1-10) MeV energy band for selected AGN and explore how much they contribute to the total diffuse $\gamma$-ray background. For this purpose, a series of imaging observations of extragalactic objects in the low-energy $\gamma$-ray region were carried out by the University of New Hampshire's Coded Aperture Directional Gamma-Ray Telescope (DGT). The DGT was successfully flown at stratospheric balloon altitudes on 1988, May 11 when observations were made of the Crab, NGC 1275, MKN 421, and NGC 4151. The measured Crab spectrum is consistent with a featureless power-law …
A Study Of Ion Acceleration At Rocket Altitudes And Development And Calibration Of Pitch Angle Imaging Charged Particle Detectors, Gregory Paul Garbe
A Study Of Ion Acceleration At Rocket Altitudes And Development And Calibration Of Pitch Angle Imaging Charged Particle Detectors, Gregory Paul Garbe
Doctoral Dissertations
Data obtained from the January 1988 flight of the Topaz 2 sounding rocket will be presented. It has been found that four types of ion populations were observed during this flight. During the early portions of the upleg and late portions of the downleg numerical fits of the plasma will be compared with in-situ data to show the Maxwellian behavior and derived plasma parameters. Throughout the middle portion of the flight superthermal tails (ion conics) were observed and are modeled using a bi-Maxwellian distribution function from which T$\sb{\rm perp}$ and T$\sb{\rm par}$ can be derived. Two other ion populations were …
Measurement Of Positron-Electron Going To Baryon-Antibaryon Forward-Backward Charge Asymmetry., Jit Ning Lim
Measurement Of Positron-Electron Going To Baryon-Antibaryon Forward-Backward Charge Asymmetry., Jit Ning Lim
LSU Historical Dissertations and Theses
This dissertation describes the measurement of the forward-backward charge asymmetry, A$\sb{\rm b}$, for e$\sp{+}$e$\sp{-} \to$ bb at TRISTAN by the AMY detector. A measurement of the ratio, R$\sb{\rm b}$, of the cross section for e$\sp{+}$e$\sp{-} \to$ bb to the theoretical QED cross section for e$\sp{+}$e$\sp{-}\ \to\ \mu\sp{+}\mu\sp{-}$ is also obtained. A$\sb{\rm b}$ is an effect of the weak-electromagnetic interference. The measurement of A$\sb{\rm b}$ is therefore a direct test of the standard model electroweak theory. TRISTAN is the only e$\sp{+}$e$\sp{-}$ collider in the world to explore the center-of-mass energy region of 50 GeV to 62 GeV, where the effects of …
Particle Production Characteristics In Central Nucleus-Nucleus Collisions At 14.6, 60 And 200 Gev/Nucleon., Oscar Edwin Pruet
Particle Production Characteristics In Central Nucleus-Nucleus Collisions At 14.6, 60 And 200 Gev/Nucleon., Oscar Edwin Pruet
LSU Historical Dissertations and Theses
Nuclear emulsions have been exposed to a series of relativistic heavy ion beams at Brookhaven National Laboratory ($\sp{16}$O and $\sp{28}$Si nuclei at 14.6 GeV/nucleon) and CERN ($\sp{16}$O nuclei at 60 and 200 GeV/nucleon and $\sp{32}$S nuclei at 200 GeV/nucleon). These beams represent the highest energies currently available for heavy projectiles. Central collisions between the beam nuclei and the heavy emulsion components $\sp{108}$Ag and $\sp{80}$Br have been compared with proton-emulsion data at equivalent energies. The multiplicities of produced charged particles are generally consistent with a conservative superposition model of nucleus-nucleus interactions. The pseudo-rapidity distributions of produced particles are gaussian in their …
Quantum Monte Carlo Simulations Of Hubbard And Anderson Models., Yi Zhang
Quantum Monte Carlo Simulations Of Hubbard And Anderson Models., Yi Zhang
LSU Historical Dissertations and Theses
We present, in this dissertation, a numerical simulation method to study interacting fermion systems. The general simulation procedures are discussed in connection with a description of a Quantum Monte Carlo simulation algorithm for interacting electrons on lattices. The algorithm presented here has been used to simulate interacting electrons on lattices, and it makes possible the study of substantially larger systems than can be studied by other numerical methods. As long as certain limits of applicability are respected, model Hamiltonians of interacting electrons can be studied without resort to uncontrolled approximations. The method then provides nearly exact solutions to model Hamiltonians …
Neutron Star Magnetic Fields And Implications For Pulsars And Gamma Ray Bursts., Yeming Sang
Neutron Star Magnetic Fields And Implications For Pulsars And Gamma Ray Bursts., Yeming Sang
LSU Historical Dissertations and Theses
Calculations of ohmic decay of neutron star dipolar magnetic fields which are confined to the neutron star crust are carried out. It is shown that the field does not decay exponentially as has been assumed in most analyses of pulsar observations and that if it occupies the entire crust it decays by less than a factor of order 100 in a Hubble time. Fields that are confined to the outer regions of the crust decay faster and again non-exponentially. We also show that the surface magnetic fields of young pulsars may fluctuate and even change polarities on time-scales much shorter …
Asymptotic Flatness And Peeling., Mark G. Naber
Asymptotic Flatness And Peeling., Mark G. Naber
Electronic Theses and Dissertations
The properties of Asymptotically flat space-times are considered with emphasis on Peeling. Penrose's method of conformal mapping is used to define Asymptotes, Asymptotic Simplicity and Asymptotically flat space-times. The boundary manifold is examined by the behavior of its geometrical properties and by group theoretic means. The behavior of massless fields on flat and curved space-times is considered with the final results being the Peeling theorems. The Peeling theorems are used to examine the asymptotic behavior of physical quantities associated with massless fields. Asymptotically flat space-times which do not peel are also briefly considered.Dept. of Physics. Paper copy at Leddy Library: …
Measurement Of The Atomic Lifetime Of Krypton Ii 5p Quantum Stat D With 4 Multiplicity And 7/2 Spin And Xenon Ii 6p Quantum State D With 4 Multiplicity And 5/2 Spin Using The Photon-Photon Delayed Coincidence Technique, Roy Edward Mitchell
Digitized Theses
A new high-efficiency photon-photon delayed coincidence lifetime measuring apparatus has been constructed and was used to study the 5d {dollar}\sp4{dollar}F{dollar}\sb{lcub}9/2{rcub}{dollar} {dollar}\longrightarrow{dollar} 5p {dollar}\sp4{dollar}D{dollar}\sbsp{lcub}7/2{rcub}{lcub}\rm o{rcub}{dollar} {dollar}\longrightarrow{dollar} 5s {dollar}\sp4{dollar}P{dollar}\sb{lcub}5/2{rcub}{dollar} cascade in Kr II and the 6d {dollar}\sp4{dollar}F{dollar}\sb{lcub}7/2{rcub}{dollar} {dollar}\longrightarrow{dollar} 6p {dollar}\sp4{dollar}D{dollar}\sbsp{lcub}5/2{rcub}{lcub}\rm o{rcub}{dollar} {dollar}\longrightarrow{dollar} 6s {dollar}\sp4{dollar}P{dollar}\sb{lcub}3/2{rcub}{dollar} cascade in Xe II. A neutral atomic beam was excited and ionized by electron impact, and the spontaneously emitted photons were collected by an ellipsoidal mirror, collimated by an aspheric lens, and detected by two Amperex XP2020Q fast linear-focussed photomultipliers provided with narrow-band interference filters. The spectrum of time delays was acquired by a time-to-amplitude converter-multichannel pulse-height analyser …
Low-Energy Positron Channeling, Lyndon Ronald Logan
Low-Energy Positron Channeling, Lyndon Ronald Logan
Digitized Theses
This thesis contains the results of both experimental and theoretical studies of low-energy positron channeling in solids. The experimental work describes investigations of both axial and planar positron channeling in Si over a range of incident energies from 8 to 50 keV. Strong channeling effects are observed and these are examined with regard to the classical description as well as the expected onset of quantum-mechanical effects. To describe the latter, a full discussion of the quantum-mechanical channeling problem is given for the planar case. In this, we present an analytical model which we use to describe the role of positron …
Posthydrogenation Of Silicon Thin Films, Xingwei Wu
Posthydrogenation Of Silicon Thin Films, Xingwei Wu
Digitized Theses
Post-hydrogenation effect on disordered silicon material made by different methods has been studied. It has been found that post-hydrogenation can effectively improve the electrical properties of such material. No Staebler-Wronski effect has been found in these post-hydrogenated samples.;Two different hydrogenation processes performed by theta-pinched plasma gun and CW atom gun have been studied. Hydrogen profiling was carried out by {dollar}\sp{lcub}15{rcub}{dollar}N Nuclear Resonance Reaction method and Secondary Ion Mass Spectrometry. The density of silicon dangling bonds before and after hydrogenation has been studied by Electron Spin Resonance (ESR) method. Hydrogen diffusion in silicon has also been studied in great detail. A …
Hall Effect Of Amorphous Silicon Fabricated By A Low-Pressure Chemical Vapour Deposition Method, Ning Du
Hall Effect Of Amorphous Silicon Fabricated By A Low-Pressure Chemical Vapour Deposition Method, Ning Du
Digitized Theses
Hall Effect measurements on various amorphous materials reported so far have the following common features: (i) the Hall mobility lies between 0.01 to 0.1 cm{dollar}\sp2{dollar}/V.s. at room temperature and increases slightly with the measurement temperature; (ii) the sign of Hall coefficient is anomalous. We have started an extensive research program to study the Hall effect of a-Si thin films fabricated by the LPCVD (low pressure chemical vapour deposition) method and observed, for the first time, normal Hall coefficient in some amorphous LPCVD samples with good network structured. For instance, the Hall mobility of sample CP119 (phosphorus doped) is 0.16cm{dollar}\sp2{dollar}/V.s. and …
Characteristics Of Large Aspect Angle Vhf Radar Echoes In The Presence And Absence Of Optical Aurora, Gregory E. Hall
Characteristics Of Large Aspect Angle Vhf Radar Echoes In The Presence And Absence Of Optical Aurora, Gregory E. Hall
Digitized Theses
For many years, researchers have been puzzled by the occurrence of strong, large aspect angle radar auroral echoes. Strong aspect sensitivities of up to 10 dB per degree have been observed at small aspect angles while large aspect angle measurements show much weaker and highly variable aspect sensitivities. It is the purpose of this thesis to attempt to understand the different results at the large aspect angles.;For this study, data from the radars and optical instruments of the CANOPUS ground based system in central Canada have been examined. The two radars (the BARS radars) operate at VHF (48.5 MHz) and …
Stokes Parameter Studies Of Electron-Rare Gas Collisions., John Jay. Corr
Stokes Parameter Studies Of Electron-Rare Gas Collisions., John Jay. Corr
Electronic Theses and Dissertations
Electron impact excitation of the rare gases has been studied via a series of polarisation correlation Stokes parameter measurements performed on an electron-photon coincidence apparatus. The Stokes parameters yield fundamental information on the magnitudes and relative phases of the scattering amplitudes which describe the scattering process, and also yield basic information about the elements of the density matrix describing the excited atomic state. Use of an in-plane polarisation analyser allowed a detailed study of the relative so-called "height" of the excited state charge cloud immediately following the electron-atom collision. A breakdown of the reflection symmetry, with respect to the scattering …
Laser-Induced Fluorescence Measurements On Electron-Impact Excited Molecules., Murray Ronald. Darrach
Laser-Induced Fluorescence Measurements On Electron-Impact Excited Molecules., Murray Ronald. Darrach
Electronic Theses and Dissertations
An electron-impact excited jet-cooled molecular beam was probed by a tunable dye laser system allowing elucidation of the electron-impact ionization and dissociation processes. This technique has been applied to the study of the rotational ground state and excited state populations of electron-impact excited N$\sb2\sp{+}$. Following electron-impact dissociation of acetonitrile, water and methanol similar measurements have been performed on the rotational populations of CN(X) and OH(X). We also present results for the absolute cross section for the electron-impact formation of CN(X) from CH$\sb3$CN. Measurements have also been performed on the relative cross section for the electron impact dissociation of OH(X) from …