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Odd-Z Transactinide Compound Nucleus Reactions Including the Discovery of 260Bh (open access)

Odd-Z Transactinide Compound Nucleus Reactions Including the Discovery of 260Bh

Several reactions producing odd-Z transactinide compound nuclei were studiedwith the 88-Inch Cyclotron and the Berkeley Gas-Filled Separator at the LawrenceBerkeley National Laboratory. The goal was to produce the same compound nucleus ator near the same excitation energy with similar values of angular momentum via differentnuclear reactions. In doing so, it can be determined if there is a preference in entrancechannel, because under these experimental conditions the survival portion of Swiatecki, Siwek-Wilcznska, and Wilczynski's"Fusion By Diffusion" model is nearly identical forthe two reactions. Additionally, because the same compound nucleus is produced, theexit channel is the same. Four compound nuclei were examined in this study: 258Db, 262Bh, 266Mt, and 272Rg. These nuclei were produced by using very similar heavy-ion induced-fusion reactions which differ only by one proton in the projectile or target nucleus (e.g.: 50Ti + 209Bi vs. 51V + 208Pb). Peak 1n exit channel cross sections were determined for each reaction in each pair, and three of the four pairs' cross sections were identical within statistical uncertainties. This indicates there is not an obvious preference of entrancechannel in these paired reactions. Charge equilibration immediately prior to fusionleading to a decreased fusion barrier is the likely cause of this phenomenon. In addition …
Date: May 14, 2008
Creator: Nelson, Sarah L & Nelson, Sarah L
System: The UNT Digital Library
Study of Nuclear Reactions with 11C and 15O Radioactive Ion Beams (open access)

Study of Nuclear Reactions with 11C and 15O Radioactive Ion Beams

Nuclear reaction study with radioactive ion beams is one of the most exciting research topics in modern nuclear physics. The development of radioactive ion beams has allowed nuclear scientists and engineers to explore many unknown exotic nuclei far from the valley of nuclear stability, and to further our understanding of the evolution of the universe. The recently developed radioactive ion beam facility at the Lawrence Berkeley National Laboratory's 88-inch cyclotron is denoted as BEARS and provides {sup 11}C, {sup 14}O and {sup 15}O radioactive ion beams of high quality. These moderate to high intensity, proton-rich radioactive ion beams have been used to explore the properties of unstable nuclei such as {sup 12}N and {sup 15}F. In this work, the proton capture reaction on {sup 11}C has been evaluated via the indirect d({sup 11}C, {sup 12}N)n transfer reaction using the inverse kinematics method coupled with the Asymptotic Normalization Coefficient (ANC) theoretical approach. The total effective {sup 12}N {yields} {sup 11}C+p ANC is found to be (C{sub eff}{sup 12{sub N}}){sup 2} = 1.83 {+-} 0.27 fm{sup -1}. With the high {sup 11}C beam intensity available, our experiment showed excellent agreement with theoretical predictions and previous experimental studies. This study also indirectly confirmed …
Date: May 14, 2007
Creator: Lee, Dongwon
System: The UNT Digital Library
Small-Angle Neutron-Proton Scattering at 90 and 290 Mev (open access)

Small-Angle Neutron-Proton Scattering at 90 and 290 Mev

From abstract: "The relative differential neutron-proton scattering cross section has been measured in the range of center-of-mass angles from 5.1° to 36.0° for approximately 90-Mev neutrons and from 10.7° to 37.8° for approximately 290-Mev neutrons."
Date: September 14, 1954
Creator: Easley, James Warren
System: The UNT Digital Library
Parametic Study of the current limit within a single driver-scaletransport beam line of an induction Linac for Heavy Ion Fusion (open access)

Parametic Study of the current limit within a single driver-scaletransport beam line of an induction Linac for Heavy Ion Fusion

The High Current Experiment (HCX) at Lawrence Berkeley National Laboratory is part of the US program that explores heavy-ion beam as the driver option for fusion energy production in an Inertial Fusion Energy (IFE) plant. The HCX is a beam transport experiment at a scale representative of the low-energy end of an induction linear accelerator driver. The primary mission of this experiment is to investigate aperture fill factors acceptable for the transport of space-charge-dominated heavy-ion beams at high intensity (line charge density {approx}0.2 {micro}C/m) over long pulse durations (4 {micro}s) in alternating gradient focusing lattices of electrostatic or magnetic quadrupoles. This experiment is testing transport issues resulting from nonlinear space-charge effects and collective modes, beam centroid alignment and steering, envelope matching, image charges and focusing field nonlinearities, halo and, electron and gas cloud effects. We present the results for a coasting 1 MeV K{sup +} ion beam transported through ten electrostatic quadrupoles. The measurements cover two different fill factor studies (60% and 80% of the clear aperture radius) for which the transverse phase-space of the beam was characterized in detail, along with beam energy measurements and the first halo measurements. Electrostatic quadrupole transport at high beam fill factor ({approx}80%) is …
Date: February 14, 2007
Creator: Prost, Lionel Robert
System: The UNT Digital Library
SQUID-Detected MRI in the Limit of Zero Static Field (open access)

SQUID-Detected MRI in the Limit of Zero Static Field

This thesis describes an implementation of the so-called&quot;zero-field MRI&quot; (ZFMRI) pulse sequence, which allows for imaging in an arbitrarily low B<sub>0</sub> field. The ZFMRI sequence created an effective unidirectional gradient field by using a train of pi pulses to average out the concomitant gradient components during encoding. The signals were acquired using a low-transition temperature dc Superconducting QUantum Interference Device (low-Tc dc SQUID) coupled to a first-order axial gradiometer. The experiments were carried out in a liquid helium dewar which was magnetically shielded with a single-layer mu-metal can around the outside and a superconducting Pb can contained within the helium space. We increased the filling factor of the custom-made, double-walled Pyrex insert by placing the liquid alcohol sample, at a temperature of approximately -50 degrees C, at the center of one loop of the superconducting gradiometer, which was immersed in the helium bath.
Date: December 14, 2009
Creator: Kelso, Nathan Dean
System: The UNT Digital Library
Scattering of K<sup>+</sup> Mesons Off Protons (open access)

Scattering of K<sup>+</sup> Mesons Off Protons

The total K/sup +/-p cross section was measured at the three K/sup +/- meson energies 175 er inch per 25, 225 er inch per 25, and 275 er inch per 25 Mev and the differential scattering cross section was measured at 225 Mev. The K/sup +/-p nuclear force was shown to be repulsive from the observed constructive interference with Coulomb scattering. The differential c=oss section was otherwise isotropic and could arise from either pure S-wave or pure P- wave scattering. Subtracted dispersion relations were applied to these data and the rest of the available K proton scattering data. The statistical errors on the data were found to be too large to determine the K-hyperon relative parity. However, if the K DELTA and K SIGMA relative parities are assumed to be the same, then if the coupling were scalar, the coupling constant g/sup 2/4 pi would be less than 0.6; if pseudoscalar, less than 10. (auth)
Date: May 14, 1959
Creator: Kycia, Thaddeus F.
System: The UNT Digital Library
Digital multiple peak and valley detector system (open access)

Digital multiple peak and valley detector system

None
Date: November 14, 1974
Creator: Gray, D.H.
System: The UNT Digital Library
The High Temperature, High Vacuum Vaporization and Thermodynamic Properties of Uranium Dioxide (open access)

The High Temperature, High Vacuum Vaporization and Thermodynamic Properties of Uranium Dioxide

None
Date: September 14, 1955
Creator: Ackermann, R. J.
System: The UNT Digital Library
Diffusion in silicon isotope heterostructures (open access)

Diffusion in silicon isotope heterostructures

The simultaneous diffusion of Si and the dopants B, P, and As has been studied by the use of a multilayer structure of isotopically enriched Si. This structure, consisting of 5 pairs of 120 nm thick natural Si and {sup 28}Si enriched layers, enables the observation of {sup 30}Si self-diffusion from the natural layers into the {sup 28}Si enriched layers, as well as dopant diffusion from an implanted source in an amorphous Si cap layer, via Secondary Ion Mass Spectrometry (SIMS). The dopant diffusion created regions of the multilayer structure that were extrinsic at the diffusion temperatures. In these regions, the Fermi level shift due to the extrinsic condition altered the concentration and charge state of the native defects involved in the diffusion process, which affected the dopant and self-diffusion. The simultaneously recorded diffusion profiles enabled the modeling of the coupled dopant and self-diffusion. From the modeling of the simultaneous diffusion, the dopant diffusion mechanisms, the native defect charge states, and the self- and dopant diffusion coefficients can be determined. This information is necessary to enhance the physical modeling of dopant diffusion in Si. It is of particular interest to the modeling of future electronic Si devices, where the nanometer-scale …
Date: May 14, 2004
Creator: Silvestri, Hughes Howland
System: The UNT Digital Library
Radiative corrections in hydrogen-like systems (open access)

Radiative corrections in hydrogen-like systems

None
Date: May 14, 1973
Creator: Mohr, P. J.
System: The UNT Digital Library
The Solubility of Hydrogen in Non-Polar Solvents (open access)

The Solubility of Hydrogen in Non-Polar Solvents

None
Date: January 14, 1954
Creator: Cook, M. W.
System: The UNT Digital Library
Interactive computer graphics system applied to the life sciences (open access)

Interactive computer graphics system applied to the life sciences

None
Date: December 14, 1973
Creator: Watson, C R
System: The UNT Digital Library
Electron beam--deuterated target experiment (open access)

Electron beam--deuterated target experiment

None
Date: June 14, 1974
Creator: Freeman, B.L. Jr.
System: The UNT Digital Library
An Experiment in School/Museum/University Collaboration (open access)

An Experiment in School/Museum/University Collaboration

A thesis submitted by Dr. Jack Davis, Dean and Professor, School of Visual Arts, University of North Texas, and Dr. William McCarter, Regents Professor of Art, School of Visual Arts, University of North Texas, titled "An Experiment in School/Museum/University Collaboration," January 14, 1994. The thesis describes the formation and work of the North Texas Institute for Educators on the Visual Arts, a consortia of six school districts, five museums, two arts councils, two state agencies and the University of North Texas. The institute it committed to the improvement of visual arts education for elementary children and developing audiences for the rich museum resources.
Date: January 14, 1994
Creator: Davis, Donald Jack & McCarter, William, 1939-
System: The UNT Digital Library
Deformation and Fracture of Polycrystalline Lithium Fluoride (open access)

Deformation and Fracture of Polycrystalline Lithium Fluoride

Techniques for forming polycrystalline LiF from the melt and for fabricating test specimens were developed and evaluated using single-crystal LiF as a control. Large -grain polycrystalline specimens tested in fourpoint loading always showed some plastic deformation (0.078 to 0.798%) before fracture, but the plastic flow was sharpiy reduced from that of single crystals. An etch was developed revealing dislocations on all crystallographic faces of LiF. Details of plastic deformation in polycrystalline material were investigated. Deformation was inhomogeneous among the grains of an aggregate because of differences in orientation with respect to the applied stress, also within individual grains because of interactions between adjoining grains. Grain boundaries were barriers to slip, but stresses resulting from slip in one grain were transmitted to neighboring grains and often caused local deformation near the boundary. Because of local stresses, local slip systems operated although the resolved shear stresses on them from the applied load were below the critical yield stress. In one case, slip occurred on an (010) plane. Three-grain junctions were areas of high residual stress. Fractures originated at boundaries at or near 3-grain junctions, not as a result of inherent boundary weakness but rather because of high stresses developed at the boundary. …
Date: September 14, 1962
Creator: Scott, W. D.
System: The UNT Digital Library
Scanning angle Raman spectroscopy: Investigation of Raman scatter enhancement techniques for chemical analysis (open access)

Scanning angle Raman spectroscopy: Investigation of Raman scatter enhancement techniques for chemical analysis

This thesis outlines advancements in Raman scatter enhancement techniques by applying evanescent fields, standing-waves (waveguides) and surface enhancements to increase the generated mean square electric field, which is directly related to the intensity of Raman scattering. These techniques are accomplished by employing scanning angle Raman spectroscopy and surface enhanced Raman spectroscopy. A 1064 nm multichannel Raman spectrometer is discussed for chemical analysis of lignin. Extending dispersive multichannel Raman spectroscopy to 1064 nm reduces the fluorescence interference that can mask the weaker Raman scattering. Overall, these techniques help address the major obstacles in Raman spectroscopy for chemical analysis, which include the inherently weak Raman cross section and susceptibility to fluorescence interference.
Date: March 14, 2013
Creator: Meyer, Matthew W.
System: The UNT Digital Library
Controlling atomistic processes on Pb films via quantum size effects and lattice rotation (open access)

Controlling atomistic processes on Pb films via quantum size effects and lattice rotation

The two main techniques used to record the data in this dissertation were Spot Profile Analysis - Low Energy Electron Diffraction (SPA-LEED) and Scanning Tunneling Microscopy (STM). A specific data analysis technique for LEED data called G(S) curves is described in depth. G(S) curves can provide a great deal of structural information about the surface; including step heights, island size, and island separation. The effects of quantum size effects (QSE) on the diffusion and critical island sizes of Pb and In on Pb #12;films are reported. Pb depositions on the 2D In phases {radical}3 and {radical}31 to see how the phases affect the Pb growth and its strong QSE are reported.
Date: June 14, 2012
Creator: Binz, Steven
System: The UNT Digital Library
Toward Understanding Dynamic Annealing Processes in Irradiated Ceramics (open access)

Toward Understanding Dynamic Annealing Processes in Irradiated Ceramics

None
Date: January 14, 2013
Creator: Myers, M. T.
System: The UNT Digital Library
Thick Nano-Crystalline Diamond films for fusion applications (open access)

Thick Nano-Crystalline Diamond films for fusion applications

None
Date: July 14, 2010
Creator: Dawedeit, C
System: The UNT Digital Library
System of coils for increasing the volume of homogeneous field between the parallel pole faces of an electromagnet (open access)

System of coils for increasing the volume of homogeneous field between the parallel pole faces of an electromagnet

None
Date: April 14, 1975
Creator: Nelson, D.H.
System: The UNT Digital Library
Solid state nuclear magnetic resonance studies of cross polarization from quadrupolar nuclei (open access)

Solid state nuclear magnetic resonance studies of cross polarization from quadrupolar nuclei

None
Date: August 14, 1997
Creator: De Paul, S.M.
System: The UNT Digital Library
Ion Implantation of In{sub 0.53}Ga{sub 0.47}As (open access)

Ion Implantation of In{sub 0.53}Ga{sub 0.47}As

None
Date: May 14, 1999
Creator: Almonte, Marlene I.
System: The UNT Digital Library
Electron-impact ionization of atomic hydrogen (open access)

Electron-impact ionization of atomic hydrogen

Since the invention of quantum mechanics, even the simplest example of collisional breakup in a system of charged particles, e{sup {minus}} + H {r_arrow} H{sup +} + e{sup {minus}} + e{sup {minus}}, has stood as one of the last unsolved fundamental problems in atomic physics. A complete solution requires calculating the energies and directions for a final state in which three charged particles are moving apart. Advances in the formal description of three-body breakup have yet to lead to a viable computational method. Traditional approaches, based on two-body formalisms, have been unable to produce differential cross sections for the three-body final state. Now, by using a mathematical transformation of the Schrodinger equation that makes the final state tractable, a complete solution has finally been achieved, Under this transformation, the scattering wave function can be calculated without imposing explicit scattering boundary conditions. This approach has produced the first triple differential cross sections that agree on an absolute scale with experiment as well as the first ab initio calculations of the single differential cross section.
Date: February 14, 2000
Creator: Baertschy, Mark D.
System: The UNT Digital Library
Nonlinear vibrational spectroscopy of surfactants at liquid interfaces (open access)

Nonlinear vibrational spectroscopy of surfactants at liquid interfaces

None
Date: December 14, 1998
Creator: Miranda, P.B.
System: The UNT Digital Library