The elastic scattering of C/sup 12/ ions from Ar, Fe, Ni, Ag/sup 107/ In, and Ta was measured as a function of angle, at a laboratory-system energy of 124.5 Mev with the Berkeley heavy-ion linear accelerator. The experimental equipment and techniques are discussed. The angular distributions show the same general behavior as previous heavy-ion elastic scattering experiments. The experimental data were analyzed with the semiclassical Blair model as modified by McIntyre. Very good agreement with experiment was obtained. The measurements were taken with 1% statistics in order to study the structure of the angular distributions in greater detail, because only by fitting the details in the structure was it possible to obtdin unambiguous sets of parameters. The parameters indicated a nuclear radius of 1.45A/sup 1/3/ x 10/sup -13/ cm, and a nearly constant surface thick ness of 1.6 x 10/sup -13/ cm. Total reaction cross sections were obtained. A rainbow-model analysis by Goldman of the data is given. Existing alpha - and heavy-ion scattering data were analyzed with the McIntyre model and compared with previous optical-model analyses of the same data. It was found that, by independent analysis, the two models give the same imaginary phase shifts for all partial …

The Standard Model describes with a very good accuracy all interactions of the, so far, known elementary particles. However the Higgs mechanism, which gives rise to the observed mass of these particles, has not yet been confirmed. The Higgs particle has not yet been observed, and the observation or exclusion is an important test of the Standard Model. The Standard Model does not predict the mass of the Higgs particle, however it does impose some limits on the range in which this mass can lie. In direct searches a Higgs with a mass smaller than 114.4 GeV and within 162 GeV and 166 GeV has been excluded at 95% CL at the LEP and the Tevatron colliders. The analysis presented in this thesis is aimed to search for the ZH → μμb$\bar{b}$ events in 3.1 fb^-1 of data collected with the DØ detector in p$\bar{p}$ collisions at √s = 1.96 TeV.

Oxygen, nitrogen, and nitric oxide gases were passed through a system consisting of a tungsten filament, an ion gauge, and a mass spectrometer. The ion gauge recorded total pressures and the spectrometer recorded partlal pressures of O/sub 2/, N/sub 2/, NO, CO, COa, and H/sub 2/O. From the way these pressures changed with filamert temperature, the rates of conversion of O/sub 2/ to volatile tungsten oxides and O, and of NO to volatile tungsten oxides N/sub 2/ , O/sub 2/, and O were computed. The time rate of resistance change in the filament was used to compute the rate of conversion of tungsten to tungsten oxides. The filament temperatures ranged from 1950 through 2600 deg K and gas pressures ranged from 10/sup -8/ to 10/sup -6/ atm. For the tungsten-oxygen reaction, the rates of tungsten and oxygen loss were found to depend upon oxygen atom concentration on the surface. The rate of oxide power, depending upon the concentration of oxygen atoms on the surface. The reaction rate at constant oxygen pressure decreases with increasing temperature. For calculational purposes, the tungsten oxygen gas moleeules were assumed to be WO/sub 3/ only, though WO/sub 2/ and WO are other possible products. The …

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This is a brief survey of some of the popular computer systems. As many features as possible have been covered in order to get an overview of the systems under consideration.

The Cd/sup 115m/ and Cd/sup 115/ isomers produced in 12- to 340Mev proton bombardments of U/sup 238/ were isolated by radiochemical methods. The cumulative yield ratios of Cd/sup 115/Cd/sup 115m/Cd/ were determined. In the 45- Mev heliumion flssion of uranium, an estimation of the independentyield ratio of Pm/sup 148/ (5.3-day) to Pm/sup 148/ (43-day) was made. In the deuteron fission of uranium at about 20 Mevs an estimate of the independent-yield ratio of Nb/sup 95m/ to the total niobium of mass 95 was made. A literature survey on experimental isomer ratios from fission was made. The yield ratio of Sc/sup 44// Sc/sup 44/ was measured in Sc/sup 45/ ( alpha , alpha n)Sc/sup 44/ reactions with helium ions of energies between 20 and 43 Mev and at 320 Mev. The Sc/sup 44m/Sc/ sup 44/ ratio was measured in K/sup 41/( alpha ,n)Sc/sup 44/ reactions at 10 and 43 Mev. The compound-nucleus model was used to calcalate the Sc/sup 44m/Sc/sup 44/ ratios produced by the reactions /sup n44/ and Sc/sup 45/(p,pn)Sc/sup 44/ at energies 0.4 Mev above threshold. Agreement between the experimental and calculated Sc/sup 44m/Sc/sup 44/ ratio was obtained for the K/sup 41/(l0-Mev alpha ,n)Sc/sup 44/ reaction. A classical knock-on …

The energies arising from the rotation of free hydroxyl groups in the central glucose residue of a cellulose crystalline assembly, calculated using RHF, DFT, and FMO2/MP2 methods, will be presented. In addition, interactions of this central glucose residue with some of the surrounding residues (selected on the basis of the interaction strengths) are analyzed. The mechanism of acid-catalyzed hydrolysis of cellobiose, which is the repeating unit of cellulose. Energies corresponding to the different steps of this mechanism calculated using RHF and DFT are compared with those previously reported using molecular dynamics calculations and with experimental data.

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In our work we revisit Ag and Au adsorbates on Si(111)-7x7, as well as experiment with a ternary system of Pentacene, Ag and Si(111). Of particular interest to us is the Si(111)-({radical}3x{radical}3)R30{degree}–Ag (Ag-Si-{radical}3 hereafter). In this thesis I systematically e plore effects of Ag deposition on the Ag-Si-{radical}3 at different temperatures, film thicknesses and deposition fluxes. The generated insight of the Ag system on the Si(111) is then applied to generate novel methods of nanostructuring and nanowire growth. I then extend our expertise to the Au system on the Ag-Si(111) to gain insight into Au-Si eutectic silicide formation. Finally we explore behavior and growth modes of an organic molecule on the Ag-Si interface.

The formation constants for the reactions PuO{sub 2}{sup +} + H{sub 2}O = PuO{sub 2}(OH) + H{sup +} and PuO{sub 2}{sup +} + CO{sub 3}{sup 2} = PuO{sub 2}(CO{sub 3}){sup {minus}} were determined in aqueous sodium perchlorate solutions by laser-induced photoacoustic spectroscopy. The molar absorptivity of the PuO{sub 2}{sup +} band at 569 nm decreased with increasing hydroxide concentration. Similarly, spectral changes occurred between 540 and 580 nm as the carbonate concentration was increased. The absorption data were analyzed by the non-linear least-squares program SQUAD to yield complexation constants. Using the specific ion interaction theory, both complexation constants were extrapolated to zero ionic strength. These thermodynamic complexation constants were combined with the oxidation-reduction potentials of Pu to obtain Eh versus pH diagrams. 120 refs., 35 figs., 12 tabs.

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We present the results of a search in p{bar p} collisions at {radical}s = 1.8 TeV for anomalous production of events containing a photon with large transverse energy and a lepton (e or {mu}) with large transverse energy, using 86 pb{sup -1} of data collected at the Collider Detector at Fermilab during the 1994-95 collider run at the Fermilab Tevatron. The presence of large missing transverse energy (E{sub T}), additional photons, or additional leptons in these events is also analyzed. The results are consistent with standard model expectations, with the possible exception of photon-lepton events with large E{sub T}, for which the probability of a statistical fluctuation of the standard model expectation up to and above the observed level is 0.7%.

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All models of lasing action require knowledge of the physical parameters involved, of which many can be measured or estimated. The value of the terminal level lifetime is an important parameter in modeling many high power laser systems since the terminal level lifetime can have a substantial impact on the extraction efficiency of the system. However, the values of the terminal level lifetimes for a number of important laser materials such as ND:YAG and ND:YLF are not well known. The terminal level lifetime, a measure of the time it takes for the population to drain out of the terminal (lower) lasing level, has values that can range from picoseconds to microseconds depending on the host medium, thus making it difficult to construct one definitive experiment for all materials. Until recently, many of the direct measurements of the terminal level lifetime employed complex energy extraction or gain recovery methods coupled with a numerical model which often resulted in large uncertainties in the measured lifetimes. In this report we demonstrate a novel and more accurate approach which employs a pump-probe technique to measure the terminal level lifetime of 16 neodymium-doped materials. An alternative yet indirect method, which is based on the ``Energy …

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This thesis presents a measurement of the t{bar t} cross section in the all-jets channel, measured in p{bar p} collisions at a center of mass energy of 1.96 TeV, using data collected with the D0 detector. The dataset used for this analysis has an integrated luminosity equivalent to L = 162.5 {+-} 10.6 pb{sup -1}. A t{bar t} cross section measurement is a test of the Standard Model predictions for heavy quark production, and the first step towards measurements of the mass and other properties of the top quark. The presented measurement of the cross section for the process p{bar p} {yields} t{bar t} uses the decay channel where both top quarks decay to quarks. The top quark first decays to a b quark and a W boson, and then, for this particular channel, the W boson decays hadronically. Hence, events with six energetic quarks are expected, which ideally leads to events with six jets. These so called all-jets events have a significantly larger branching fraction than other t{bar t} decay channels. The large branching fraction in the all-jets channel means that a significant sample of t{bar t} candidates can be extracted, which can subsequently be used for studies of …

Thesis. The optical absorption spectra of Ho/sup 3+/ in the rare earth salt HoF/sub 3/ is studied. Such optical region studies (visible radiation) are easily performed with standard light sources and optical arrangements. Since the energy range of visible light coincides with the excitation energy range for a number of electronic transitions within the rare earth salts, the studies theoretically provide considerable information about rare earth electronic energy levels. Data are compiled for the effects of an applied magnetic field upon the spectra and the effect of sample temperature on the observed absorption spectra. 61 references. (MCW)

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Many Twain scholars believe that his skepticism was based on personal tragedies of later years. Others find skepticism in Twain's work as early as The Innocents Abroad. This study determines that Twain's atheism is evident in his earliest writings. Chapter One examines what critics have determined Twain's religious sense to be. These contentions are discussed in light of recent publications and older, often ignored, evidence of Twain' s atheism. Chapter Two is a biographical look at Twain's literary, family, and community influences, and at events in Twain's life to show that his religious antipathy began when he was quite young. Chapter Three examines Twain's early sketches and journalistic squibs to prove that his voice, storytelling techniques, subject matter, and antipathy towards the church and other institutions are clearly manifested in his early writings.

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Senior colloquium written by a student in the UNT Honors College discussing Greek sculpture and architecture as filtered through the Fauve, Constructivist, Dada, and Pop artistic movements. The author takes examples of Grecian sculpture, recreates them in each of the other styles, and discusses the results.

An investigation of the effusive behavior of saturated vapors over a range of source pressures from 10/sup -6/ atm in the molecular flow region to 1 atm is reported. The purposes of the investigation were to clarify the situation regarding the upper pressure limit to effusive flow, to examine the transition of effusive flow from molecular to viscous behavior, and to clarify some limited aspects concerning the question of vapor saturation within an effusion cell. Mass flow rates of mercury vapor effusing through a thin-edged orifice or long channels into a vacuum from a region of nearly saturated vapor were obtained. (W.D.M.)

In 2009, the American Conference of Governmental Industrial Hygienists (ACGIH) reduced the Beryllium (Be) 8-hr Time Weighted Average Threshold Limit Value (TLV-TWA) from 2.0 {micro}g/m{sup 3} to 0.05 {micro}g/m{sup 3} with an inhalable 'I' designation in accordance with ACGIH's particle size-selective criterion for inhalable mass. Currently, per the Department of Energy (DOE) requirements, the Lawrence Livermore National Laboratory (LLNL) is following the Occupational Health and Safety Administration (OSHA) Permissible Exposure Limit (PEL) of 2.0 {micro}g/m{sup 3} as an 8-hr TWA, which is also the 2005 ACGIH TLV-TWA, and an Action Level (AL) of 0.2 {micro}g/m{sup 3} and sampling is performed using the 37mm (total dust) sampling method. Since DOE is considering adopting the newer 2009 TLV guidelines, the goal of this study was to determine if the current method of sampling using the 37mm (total dust) sampler would produce results that are comparable to what would be measured using the IOM (inhalable) sampler specific to the application of high energy explosive work at LLNL's remote experimental test facility at Site 300. Side-by-side personal sampling using the two samplers was performed over an approximately two-week period during chamber re-entry and cleanup procedures following detonation of an explosive assembly containing Beryllium (Be). …

Bacteria induce the precipitation of calcium carbonate in the laboratory and in nature by altering their chemical environment. Geologists are recognizing the possibility that bacterially induced precipitates may form significant mineral deposits, unfortunately, there are currently no sound criteria by which they can be recognized in recent sediments, or in the rock record. Cultures of aerobic and facultative bacteria from cyanobacterial mats on Andros Island, Bahamas, and Baffin Bay, Texas, induced the precipitation of calcium carbonate under controlled conditions. Crusts, the largest features formed, are composed of 5--200{mu}m diameter bundles which are, in turn, composed of numerous individual crystals. The smallest observed features are 0.1--0.4{mu}m spheres and rods which comprise some individual crystals and crystal bundles. Crystal bundles resembling rhombohedra, tetragonal disphenoids, tetragonal dipyramids, and calcite dumbbells appear to be uniquely bacterial in origin, and they have all been observed in recent sediments. Swollen rods, discs, curved dumbbells, and 50--200{mu}m optically continuous crystals resembling brushes may be uniquely bacterial in origin, however, they have not been reported by other laboratories nor observed in natural settings. Presence of any of these forms in recent sediments should be taken as strong evidence for bacterial influence. Spheres and aragonite dumbbells have also been …