Undergraduate thesis studying the properties of amorphous silicon (⍺-Si) and crystalline silicon nanowires (c-Si NWs), focusing on the requirements placed on thin films by bolometers.

A search for innovative synthetic routes to new metal-metal bonded metal-halide clusters resulted in isolation of two completely independent dimeric species. The syntheses and characterizations of Ta/sub 2/X/sub 6/(SC/sub 4/H/sub 8/)/sub 3/ (X = Cl, Br) and ((n-C/sub 3/H/sub 7/)/sub 4/N)/sub 2/(W/sub 2/Br/sub 9/) followed entirely different experimental routes, yet occasionally similar properties linked the two projects. (auth)

Experimental studies have been carried out in which the A15 phase of the Nb-Al-Ge system has been synthesized in the form of thin filaments contained in form rolled wires. A powder metallurgy approach has been used to achieve controlled porosity in compacts of sintered niobium powder. Infiltration with an aluminum-germanium eutectic alloy followed by mechanical deformation has produced small interconnected filaments embedded in the Nb matrix. Diffusion heat treatment for a short time transforms them into the A15 superconducting compound with a size range of 1-5 microns at 1300/sup 0/C and 1-9 microns at 1750/sup 0/C. The superconducting properties T/sub c/ and J/sub c/ were evaluated for samples subjected to different condition of time and temperature. The influence of certain parameters involved in the process has been investigated. The microstructure and microhardness of the Al-Ge eutectic alloy cooled at high and low cooling rates from temperatures between 900-400/sup 0/C have been evaluated. Optical and electron beam metallographic results are presented for the analysis of the different phases and relative compositions. The critical temperature measured inductively is between 16.4/sup 0/K and 18.1/sup 0/K depending on the heat treatment. The critical current density as a function of the applied magnetic field is …

A detailed interpretation is presented of E-field ratio telluric, bipole-dipole resistivity mapping, and dipole-dipole resistivity data obtained in the course of geophysical exploration of the Leach Hot Springs area of Grass Valley, Nevada. Several areas are singled out as being worthy of further investigation of their geothermal potential. Comparison of the three electrical exploration techniques indicates that: the bipole-dipole resistivity mapping method is the least useful; the dipole-dipole resistivity method can be very useful, but is, for practical purposes, exceptionally expensive and difficult to interpret; the E-field ratio telluric method can be a highly successful reconnaissance technique for delineating structures and relating the resistivities of different regions within the survey area.

Four sialon-type materials using volcanic ash as a raw material were characterized and some of their properties were determined. The M3 and M4 materials were identified as ..beta../sup 1/--Si/sub 3/N/sub 4/ sialons; their principal constituent is silicon. The M2 material was identified as a 15R-A1N polytype sialon whose principal constituent is aluminum. The M1 material is a mixture of the two types. An overview of results showing the general structural formulae and the relative order of the materials with respect to various properties as determined by the investigation is presented. It is concluded that of the materials tested, the M2 material shows the most promise as a candidate for meeting some of the current needs for high-temperature materials. It is also concluded that more research is needed in order to explain the low resistance of these materials to thermal shock since their coefficients of thermal expansion are relatively low.

Direct detection of {sup 14}C by accelerator mass spectrometry has proved to be a much more sensitive method for radiocarbon dating than the decay counting method invented earlier by Libby. A small cyclotron (the cyclotrino'') was proposed for direct detection of radiocarbon in 1980. This combined the suppression of background through the use of negative ions, which had been used effectively in tandem accelerators, with the high intrinsic mass resolution of a cyclotron. Development of a small electrostatically-focused cyclotron for use as a mass spectrometer was previously reported but the sensitivity needed for detection of {sup 14}C at natural abundance was not achieved. The major contributions of this work are the integration of a high current external ion source with a small flat-field, electrostatically-focused cyclotron to comprise a system capable of measuring {sup 14}C at natural levels, and the analysis of ion motion in such a cyclotron, including a detailed analysis of phase bunching and its effect on mass resolution. A high current cesium sputter negative ion source generates a beam of carbon ions which is pre-separated with a Wien filter and is transported to the cyclotron via a series of electrostatic lenses. Beam is injected radially into the cyclotron …

The one- and two-dimensional Ginzburg-Landau equations are numerically integrated in a slab geometry, which is appropriate for comparison to experimental work done on films. When two-dimensional variations become energetically favorable, a vortex is found to nucleate and move to the center of the film with the Gibbs free energy decreasing during the process. An important process by which the energy is lowered during this nucleation procedure is found to be the savings in condensation energy arising from the shrinking size of the vortex core as it moves to the center of the film. The solutions of the Ginzburg-Landau equations are used to explain anomalies observed experimentally in the tunneling characteristics of thin films of PbIn. Excellent agreement between theory and experiment is found with the Ginzburg-Landau equations correctly predicting the field at which flux would first enter the films. We then use the Clem model of an isolated vortex to model vortex nucleation and dynamics under the influence of a transport current. The entry fields predicted by the model are found to be off by almost a factor of two but have the advantage of requiring simple computer programs for their solution, while the Ginzburg-Landau solutions require substantially more numerical …

Chemical properties of rutherfordium (Rf) have been investigated with the organic ligands triisooctylamine (TIOA), tributylphosphate (TBP), and thenoyltrifluoroacetone (TTA). The TIOA studies showed that Rf behaves differently than Th and Eu and most similarly to Zr, only Zr and Rf extract from 12 M HCI. This result is further evidence that Rf is a Group 4 element. Studies with TBP showed that Rf chemical behavior differed from the other Group 4 elements. The extraction by TBP at different chloride concentrations showed that Rf at times behaves more like Pu{sup 4+} than Zr or Hf. At high chloride concentrations, Rf and Pu extraction decreased. Under the same conditions, Zr, Hf and Th extraction increased. In addition, Rf extraction by TBP was affected by hydrogen ion concentration, while Zr and Hf extraction was not. TTA extractions were used to determine the K{sub eq}, K{sub hyd}, and the ionic radius of Rf. The of K{sub eq} for Rf with TTA was calculated to be 3.18 {plus minus} 0.90. The first four log K{sub hyd's} for Rf are calculated to be {minus}2.6 {plus minus} 0.7, {minus}5.9 {plus minus} 1.7, {minus}10.2 {plus minus} 2.9, and {minus}14.5 {plus minus} 4.1. These hydrolysis constants indicate that Rf …

The polarized absorption spectra for K/sub 2/PtBr/sub 4/ . 2H/sub 2/O, (N(C/sub 2/H/sub 5/)/sub 4/)/sub 2/PtBr/sub 6/, and Mo/sub 2/(O/sub 2/CCH/sub 2/NH/sub 3/)/sub 4/(SO/sub 4/)/sub 2/ . 4H/sub 2/O have been recorded at 300 and 15/sup 0/K. In K/sub 2/PtBr/sub 4/ . 2H/sub 2/O the bands at 24,000 and 27,000 cm/sup -1/ in both a- and b-polarizations appear to be vibronically induced. The energy spacing of the vibrational structure was noted to be somewhat higher at 180 cm/sup -1/ than for the analogous structure of K/sub 2/PtBr/sub 4/. The presence of a Pt/sub 2/Br/sub 6//sup 2 -/ impurity gave rise to red sections, which evidently were due to the electron transfer, Pt(IV)/reverse arrow/Pt(II), occurring in c-polarization. Very weak spin-forbidden bands were observable in all three polarizations below 23,500 cm/sup -1/. In the crystal spectra of (N(C/sub 2/H/sub 5/)/sub 4/)/sub 2/Pt/sub 2/Br/sub 6/ the transitions were defined with respect to the three molecular axes of the Pt/sub 2/Br/sub 6//sup 2 -/ ion. Excited states were assigned under the D/sub 2//sub h/ point group symmetry of the ion. The delocalization of the d electrons gave rise to strongly enhanced intensities for both spin-forbidden and spin-allowed d/reverse arrow/d transitions. The M/reverse arrow/L charge-transfer …

A method is developed to optimize the separated-pair independent particle (SPIP) wave function; it is a special case of the separated-pair theory obtained by using two-term natural expansions of the geminals. The orbitals are optimized by a theory based on the generalized Brillouin theorem and iterative configuration interaction (CI) calculations in the space of the SPIP function and its single excitations. The geminal expansion coefficients are optimized by serial 2 x 2 CI calculations. Formulas are derived for the matrix elements. An algorithm to implement the method is presented, and the work needed to evaluate the molecular integrals is discussed. (auth)

A special hydriding system was designed and constructed to satisfy conditions for hydriding niobium. This system controlled the temperature and hydrogen atmosphere surrounding the niobium while ultrasonic measurements were recorded. Ultrasonic wave velocities were determined by measurement of the times for ultrasonic pulses to transit and then echo through known dimensions of test specimens. The method which was employed is commonly known as the pulse-echo-overlap method. This study confirmed the general trends of earlier investigations. In this study C' continued to decrease and C/sub 44/ continued to increase up to 4.69 atomic percent hydrogen which is the maximum concentration which has yet been examined. In the case of the niobium-hydrogen system the Snoek effect may well be a contributory factor to the decrease of C' with increasing hydrogen concentration. However, crystallographic considerations preclude this effect from contributing a concentration dependence to C/sub 44/ or B. The observation of the present work implies that other factors must also be contributing to the overall behavior.

The development of a unique type of large superconducting solenoid magnet, characterized by very high current density windings and a two-phase helium tubular cooling system is described. The development of the magnet's conceptual design and the construction of two test solenoids are described. The successful test of the superconducting coil and its tubular cooling refrigeration system is presented. The safety, environmental and economic impacts of the test program on future developments in high energy physics are shown. Large solid angle particle detectors for colliding beam physics will analyze both charged and neutral particles. In many cases, these detectors will require neutral particles, such as gamma rays, to pass through the magnet coil with minimum interaction. The magnet coils must be as thin as possible. The use of superconducting windings allows one to minimize radiation thickness, while at the same time maximizing charged particle momentum resolution and saving substantial quantities of electrical energy. The results of the experimental measurements show that large high current density solenoid magnets can be made to operate at high stored energies. The superconducting magnet development described has a positive safety and environmental impact. The use of large high current density thin superconducting solenoids has been proposed …

The crystal and molecular structures of the following organophosphorus (OP) insecticides have been determined by three-dimensional X-ray analysis: ronnel (0,0-dimethyl 0-2,4,5 trichlorophenyl phosphorothioate), ronnel oxon (0,0-dimethyl 0-2,4,5 trichlorophenyl phosphate), bomophos (0-(4-bromo-2,5-dichlorophenyl) 0,0-dimethyl phosphorothioate), Ruelene (0-(4-tert-Butyl-2-chlorophenyl)-0-methyl-N-methyl phosphoroamidate), fospirate (0,0-dimethyl 0-3,5,6-trichloro-2-pyridyl phosphate) and chlorpyrifos (0,0-diethyl 0-3,5,6-trichloro-2-pyridyl phosphorothioate). Phosphorus to meta hydrogen distances for the respective compounds are: 5.51, 5.49, 5.42, (5.68, 5.13), 5.79 and 5.78 A. All of these distances fall well within the range of literature values cited for the intramolecular active site-separation distance for insect acetylcholinesterase (AChE), yet are well outside that for mammalian AChE. In addition the crystal structure of ronnel displays a hydrogen-sulfur intermolecular interaction in the b direction and a phosphorus which is readily accessible for phosphorylation of AChE. The structure of ronnel oxon is quite similar to that of ronnel. CNDO 11 molecular orbital calculations are presented to show the charge distribution in the compound. A likely intramolecular hydrogen bond in bromophos restricts rotation about the phenolic C-O bond. The configuration of Ruelene is substantiated by CNDO 11 molecular orbital calculations and van der Waals arguments and features a possible weak intramolecular hydrogen bond which somewhat restricts rotation about the phenolic C-O bond. Charge density information …

Results are reported from an investigation of correlations between molecular structural parameters of selected organophosphorus insecticides and their corresponding toxic effectiveness. The crystal and molecular structures of azinphos-methyl, emidithion, and tetrachlorvinphos were determined via three-dimensional x-ray analysis. Acetylcholinesterase (AChE) in nerve cells was identified as the target for organophosphorus insecticides.

Commercial secondary hardening steel, VASCO MA, has been subjected to modified heat treatments to introduce mixed microstructures of martensite and lower bainite. Dilatometry, tensile testing, hardness measurements and slow-bend testing have been carried out and the mechanical properties obtained have been correlated to microstructure using scanning electron microscopy and metallography. Duplex microstructures containing small amounts of lower bainite are found to show an increased toughness (at similar strength levels) on tempering in the secondary hardening range, as compared to initially fully martensitic microstructures. As the percentage of lower bainite in the duplex microstructures is increased, the secondary hardening peak is found to attenuate. The effect of different austenitization treatments on the secondary hardening behavior, has also been studied. Thermal cycling (for grain refinement) at lower austenitization temperatures is found to reprecipitate out carbon, which has been taken into solution in earlier high temperature austenitization, thereby leading to a significant depletion in the strength of this secondary hardening steel. Alloy carbides, in the secondary hardening stage, have also been analyzed using energy dispersive analysis of x-rays.

An improved electrostatic precipitator called a space charge precipitator was tested and studied. A space charge precipitator differs from a conventional model in that the fields necessary to move the particles from the gas to the collecting surfaces are provided by a cloud of charged innocuous drops, such as glycerine or water, rather than by a charged electrode system. The flow conditions, electrical equipment, and physical dimensions of the test precipitator are typical of industrial applications. Experiments using water fog at a velocity of 10 ft/sec and a residence time of 0.6 sec, for a system charged at 25 kV, show a removal of iron oxide particles of approximately 52 percent. Theoretical calculations, assuming 2 micron particles, predict a removal of 50 percent. The results with glycerine fog are comparable. Experiments at various flowrates for both water fog and glycerine fog show a trend of decreasing particle removal for increasing flowrate. An identical trend is predicted by the space charge theory. Electron micrographs verify that only particles smaller than two microns are present in the laboratory precipitator.

Two mathematical methods are utilized (one a form of adiabatic approximation, and the other closely related to the Zener method from collision theory) in order to calculate the probability of three-photon ionization when strong counter propagating pulses are tuned very near a two-photon resonant state. In this case the inverted populations predicted by Grischkowsky and Loy for smooth laser pulses lead to larger ionization probabilities than would be obtained for a square pulse of equal peak power and energy per pulse. The line shape of the ionization probability is also quite unusual in this problem. A sharp onset in the ionization probability occurs as the lasers are tuned through the exact unperturbed two-photon resonance. Under proper conditions, the change can be from a very small value to one near unity. It occurs in a very small frequency range determined by the larger of the residual Doppler effect and the reciprocal duration of the pulse. Thus, the line shape retains a Doppler-free aspect even at power levels such that power broadening would dwarf even the full Doppler effect in the case of a square pulse of equal energy and peak power. The same mathematical methods have been used to calculate line …

A comprehensive theoretical study has been carried out on the flow behavior of both single and multiple phase non-Newtonian fluids in porous media. This work is divided into three parts: development of numerical and analytical solutions; theoretical studies of transient flow of non-Newtonian fluids in porous media; and applications of well test analysis and displacement efficiency evaluation to field problems. A fully implicit, integral finite difference model has been developed for simulation of non-Newtonian and Newtonian fluid flow through porous media. Several commonly-used rheological models of power-law and Bingham plastic non-Newtonian fluids have been incorporated in the simulator. A Buckley-Leverett type analytical solution for one-dimensional, immiscible displacement involving non-Newtonian fluids in porous media has been developed. An integral method is also presented for the study of transient flow of Bingham fluids in porous media. In addition, two well test analysis methods have been developed for analyzing pressure transient tests of power-law and Bingham fluids, respectively. Applications are included to demonstrate this new technology. The physical mechanisms involved in immiscible displacement with non-Newtonian fluids in porous media have been studied using the Buckley-Leverett type analytical solution. In another study, an idealized fracture model has been used to obtain some insights into …

The proton NMR in powdered samples of H/sub 2/O(s), H/sub 2/S(s), and C/sub 6/H/sub 6/(s) have been studied by multiple pulse line narrowing techniques. The resultant spectra provide nuclear magnetic shielding tensors that are (at least approximately) axially symmetric. The anisotropy is 34.2 +- 1.0 ppM for ice, 11.1 +- 1.0 ppM for the highest-temperature phase of solid hydrogen sulfide, and -5.3 +- 0.3 for benzene. Comparisons are made with previous experimental and theoretical work.

The trivalent uranium compound, (MeC{sub 5}H{sub 4}){sub 3}U(thf), serves as a one- or two-electron reducing agent towards azides, RN{sub 3}. These reactions produce either the uranium(IV) azide, (MeC{sub 5}H{sub 4}){sub 3}UN{sub 3}, or uranium(V) imides, (MeC{sub 5}H{sub 4}){sub 3}UNR. The role of steric and electronic effects upon this reaction has been investigated using several series of azides. For Me{sub 3}XN{sub 3}, the imides are produced when X = C or Si, both products are formed when X = Ge, and the azide is produced when X = Sn. For Ph{sub 3}XN{sub 3}, the azide is produced when X = C or Sn. For Ph{sub 3-x}CH{sub 3}N{sub 3}, the imide is produced when x = 2 and both compounds are produced when x = 1. For substituted phenylazides, RC{sub 6}H{sub 4}N{sub 3}, only the imides are produced. The magnetic properties of uranium diimides, ((MeC{sub 5}H{sub 4}){sub 3}U){sub 2}({mu}-NRN), were investigated. Several uranium(III) amines, (MeC{sub 5}H{sub 4}){sub 3}U(NH{sub 2}R), were produced from (MeC{sub 5}H{sub 4}){sub 3}U(thf) and RNH{sub 2}, and NH{sub 3} was found to be a better ligand towards (MeC{sub 5}H{sub 4}){sub 3}U than is PMe{sub 3}.

A realistic lattice model is a fundamental basis for the operation of a synchrotron. In this study various beam-based measurements, including orbit response matrix (ORM) and BPM turn-by-turn data are used to verify and calibrate the lattice model of the Fermilab Booster. In the ORM study, despite the strong correlation between the gradient parameters of adjacent magnets which prevents a full determination of the model parameters, an equivalent lattice model is obtained by imposing appropriate constraints. The fitted gradient errors of the focusing magnets are within the design tolerance and the results point to the orbit offsets in the sextupole field as the source of gradient errors. A new method, the independent component analysis (ICA) is introduced to analyze multiple BPM turn-by-turn data taken simultaneously around a synchrotron. This method makes use of the redundancy of the data and the time correlation of the source signals to isolate various components, such as betatron motion and synchrotron motion, from raw BPM data. By extracting clean coherent betatron motion from noisy data and separates out the betatron normal modes when there is linear coupling, the ICA method provides a convenient means to measure the beta functions and betatron phase advances. It also …

A preliminary measurement of the t{bar t} production cross section at {radical}s = 1.96 TeV is presented. The {mu}-plus-jets final state is analyzed in a data sample of 94 pb{sup -1} and a total of 14 events are selected with a background expectation of 11.7 {+-} 1.9 events. The measurement yields: {sigma}{sub p{bar p} {yields} t{bar t} + X} = 2.4{sub -3.5}{sup +4.2}(stat.){sub -2.6}{sup +2.5}(syst.) {+-} 0.3(lumi.) pb. The analysis, being part of a larger effort to re-observe the top quark in Tevatron Run II data and to measure the production cross section, is combined with results from all available analyses channels. The combined result yields: {sigma}{sub p{bar p}} {yields} t{bar t} + X = 8.1{sub -2.0}{sup +2.2}(stat.){sub -1.4}{sup +1.6}(syst.) {+-} 0.8(lumi.) pb.

An experimental investigation was carried out to improve the froth flotation method of separating coal pyrite. The effect of several surface active agents on the floatability of an Iowa coal and its associated pyrite was studied in both the presence and absence of methyl isobutyl carbinol (MIBC), a commonly used frother. The effectiveness of a special method of chemical pretreatment for depressing pyrite was also investigated. The zeta potential of the same coal and pyrite was measured under the same conditions used in the flotation tests (in the absence of frother). In the absence of MIBC, the floatability of coal and pyrite was low, and appeared to depend on pH. The maximum recovery of pyrite was obtained at a pH of 4.5 with recovery being less at higher or lower pH. The addition of a small amount of MIBC significantly increased the recovery of coal and pyrite with the increase in the recovery of coal being much greater than the increase in the recovery of pyrite. Also in the presence of MIBC, the floatability of coal and pyrite seemed to be affected more by pH than in the absence of MIBC. On the other hand, several potential pyrite depressants were …

Evidence from observational cosmology and astrophysics indicates that about one third of the universe is matter, but that the known baryonic matter only contributes to the universe at 4%. A large fraction of the universe is cold and non-baryonic matter, which has important role in the universe structure formation and its evolution. The leading candidate for the non-baryonic dark matter is Weakly Interacting Massive Particles (WIMPs), which naturally occurs in the supersymmetry theory in particle physics. The Cryogenic Dark Matter Search (CDMS) experiment is searching for evidence of a WIMP interaction off an atomic nucleus in crystals of Ge and Si by measuring simultaneously the phonon energy and ionization energy of the interaction in the CDMS detectors. The WIMP interaction energy is from a few keV to tens of keV with a rate less than 0.1 events/kg/day. To reach the goal of WIMP detection, the CDMS experiment has been conducted in the Soudan mine with an active muon veto and multistage passive background shields. The CDMS detectors have a low energy threshold and background rejection capabilities based on ionization yield. However, betas from contamination and other radioactive sources produce surface interactions, which have low ionization yield, comparable to that of …