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MSW effect and solar neutrino experiments

Description: We describe the MSW solutions to the /sup 37/Cl solar neutrino experiment, and their implications for the /sup 71/Ga experiment. Measurement of the spectrum of electron-type neutrinos arriving at earth is emphasized. 8 refs., 2 figs., 1 tab.
Date: January 1, 1986
Creator: Rosen, S.P.
Partner: UNT Libraries Government Documents Department

From Africa to the stars

Description: The thesis is developed that our evolutionary future, like our past, is tied to our penchant for exploration and migration. The main stages of human exploration and migration are examined, with the evolutionary implications of each, starting from the time our distant ancestors first stood upright and continuing into the coming era of space expansion. (ACR)
Date: January 1, 1983
Creator: Finney, B.R. & Jones, E.M.
Partner: UNT Libraries Government Documents Department

A mass spectrometric analysis of CF/sub 4//O/sub 2/ plasmas: Effect of oxygen concentration and plasma power

Description: A quadrupole mass analyzer was used to detect the neutral products extracted downstream from a CF/sub 4//O/sub 2/ RF discharge at 80 mtorr. Stable discharge products are reported as a function of plasma power, residence time, oxygen concentration, and plasma voltage standing-wave ratio. In general, as plasma power increased from 10 to 200 W, production of CO increased while the measured mole fractions of CO/sub 2/ and COF/sub 2/ stabilized. The ratio of CO to CO/sub 2/ decreased at low plasma powers as the oxygen concentration increased. An increase in the relative conversion of CF/sub 4/ to oxygenated products occurred at both low plasma powers and low oxygen concentrations. Several mechanisms are suggested to account for these results. 16 refs., 16 figs., 1 tab.
Date: January 1, 1988
Creator: Martz, J.C.; Hess, D.W. & Anderson, W.E.
Partner: UNT Libraries Government Documents Department

Charged-particle elastic cross sections

Description: Modern treatments of energy loss in plasmas through elastic scattering of energetic ions require complete knowledge of charged-particle elastic cross sections. R-matrix theory provides an explicit separation of nuclear and Coulomb effects in these cross sections, and gives reasonable extrapolations to small angles and low energies, where data may be scarce. We outline the calculation of charged-particle elastic cross sections from R-matrix parameters, and given examples for d-T, d-..cap alpha.., and t-..cap alpha.. scattering, obtained from comprehensive analyses of reactions in the /sup 5/He, /sup 6/Li, and /sup 7/Li compound systems. Expansion coefficients for an exact polynomial representation for the difference of the scattering and Rutherford cross sections (sigma/sub NI/) are given for d-T scattering. Integral quantities involving sigma/sub NI/ calculated from the present cross sections disagree substantially in some cases near resonances with a recent Livermore evaluation.
Date: January 1, 1982
Creator: Hale, G.M.; Dodder, D.C. & DeVeaus, J.C.
Partner: UNT Libraries Government Documents Department

Acoustic velocity measurements on fluid metals from two-fold compressions to two-fold expansions

Description: Methods used for making acoustic velocity measurements on samples which are destroyed in time scales of milliseconds or less are described. Analytic techniques for using this data to calculate thermodynamic quantities are outlined. New results indicating a linear relationship of acoustic velocity with density over a very large density range are presented. 30 refs., 5 figs. (DWL)
Date: January 1, 1986
Creator: Shaner, J.W.; Hixson, R.S.; Winkler, M.A. & Brown, J.M.
Partner: UNT Libraries Government Documents Department

A CW-pion focusing horn for low-energy muon neutrino beams

Description: Low-energy muon neutrino beams can be produced from pion decays in-flight at high-intensity accelerators, such as the Los Alamos Meson Physics Facility (LAMPF), providing a new tool to study the role of the weak interaction in nuclear and particle physics. Employing a pion focusing device can enhance the neutrino flux by large factors, and reduce backgrounds by sign-selection of the parent pions. However, LAMPF's long beam pulse and high repetition rate makes it impractical to use pulsed horns like those found at high-energy accelerators. In this paper we discuss a CW-pion focusing device that uses coils wound inside vanes mounted radially around the beam axis to provide an azimuthal field. From our studies with a prototype magnet, we have found the optimum field configuration needed to focus pions at LAMPF energies can be obtained by adjusting the radial density of turns in the coils. This optimum yields an eight-fold increase in neutrino flux above the muon threshold over the bare-target case. Our calculations also indicate a correlation between the arrival time of the neutrinos in the detector and their energy.
Date: January 1, 1988
Creator: Dombeck, T.; Koetke, D.D.; Koetke, D.S. & Fisk, R.
Partner: UNT Libraries Government Documents Department

Birch's Law for fluid metals

Description: By comparing acoustic velocities in fluid metals over a very wide range of densities we have established Birch's Law as an approximate representation over the entire liquid range. For a given liquid metal the acoustic velocity is close to linear in density, with a slope determined by the atomic weight. The measurements include isobaric expansion to less than half normal density, ultrasonics on molten metals at 1 atmosphere, and shock melted metals to greater than twice normal density.
Date: January 1, 1987
Creator: Shaner, J.W.; Hixson, R.S.; Winkler, M.A.; Boness, D.A. & Brown, J.M.
Partner: UNT Libraries Government Documents Department

Pattern selection and competition in near-integrable systems

Description: Pattern selection and competition in certain near-integrable systems are discussed. These systems provide models for controlled studies of low dimensional attractors in high (infinite) dimensional systems. Four examples from damped, driven pendulum rings are summarized in the order of increasing spatial complexity of their chaotic attractors. These examples illustrate the use of numerical and analytical techniques from soliton mathematics to study properties of chaotic attractors. In particular, the connection of (unperturbed) homoclinic states with instabilities of spatial patterns, with interactions between patterns, and as possible sources of temporal chaos is emphasized. 16 refs., 9 figs.
Date: January 1, 1986
Creator: Bishop, A.R. & McLaughlin, D.W.
Partner: UNT Libraries Government Documents Department

Quasi-linear dynamo from resistive pressure-driven instabilities

Description: The Hewett/Freidberg linear resistive MHD stability code was used to calculate the radial eigenfunctions of resistive interchange instabilities in the Reversed-Field Pinch (RFP). These data were used to calculate the quasi-linear dynamo emf. The resultant poloidal dynamo emf is found to be negative inside of reversal, zero at reversal and positive between reversal and the wall. This emf will oppose the resistive decay of toroidal magnetic flux inside of reversal. However, the lack of a dynamo emf at reversal prohibits the quasi-linear evolution of resistive pressure-driven modes from causing the increase in positive toroidal magnetic flux (i.e., the flux inside of reversal) that occurs on the ZT-40 device at Los Alamos.
Date: January 1, 1984
Creator: Werley, K.; Nebel, R. & Miley, G.
Partner: UNT Libraries Government Documents Department

Quasi-invariance (rescaling) in nonlinear physics

Description: Consider the following phase space-time transformation q/sup i/ = xi/sup i/C(t), p/sub i/ = ..pi../sub i//C(t), THETA = THETA(t) where q/sup i/, p/sub i/, t and xi/sup i/, ..pi../sub i/, THETA are the coordinate, momentum and time variables in the old and new space respectively, and where C(t) and THETA(t) are arbitrary functions of time. These transformations are shown to be generalized canonical transformations (GCT). The new variables reduce to the usual invariants of similarity solutions when such a transformation is found that leaves the governing equations strictly invariant. In most cases, for equations not completely integrable, no more than one group may usually be found. The invariants of the group are then used to absorb one independent variable, decreasing by one their number, but at the price of specializing initial conditions. For second order ordinary differential equations (including systems with friction), the method can be used to find strict or asymptotic invariants. We give two examples. The first deals with a one species plasma in cylindrical geometry embedded in a time-varying magnetic field for which the Brillouin flow is shown to be a general attractor. The second deals with the nonlinear heat-diffusion equation for which we compare the asymptotic solution to those obtained by self-similarity arguments.
Date: May 1, 1984
Creator: Munier, A. & Feix, M.R.
Partner: UNT Libraries Government Documents Department

Pressure dependence of the resistivity of Ce/sub 3/Al

Description: Ce/sub 3/Al was prepared from very high purity cerium. The resistivity at various pressures show a structural transition near 100/sup 0/K at zero pressure. This antiferromagnetic heavy fermion behavior evolves smoothly towards nonmagnetic large T/sub K/ (slightly overweight fermion) behavior as the pressure is raised. 3 figs. (DLC)
Date: January 1, 1987
Creator: Lawrence, J.M.; Chen, Y.Y.; Thompson, J.D. & Borges, H.A.
Partner: UNT Libraries Government Documents Department

Mechanism of nuclear dissipation in fission and heavy-ion reactions

Description: Recent advances in the theoretical understanding of nuclear dissipation at intermediate excitation energies are reviewed, with particular emphasis on a new surface-plus-window mechanism that involves interactions of either one or two nucleons with the moving nuclear surface and also, for dumbbell-like shapes encountered in fission and heavy-ion reactions, the transfer of nucleons through the window separating the two portions of the system. This novel dissipation mechanism provides a unified macroscopic description of such diverse phenomena as widths of isoscalar giant quadrupole and giant octupole resonances, mean fission-fragment kinetic energies and excitation energies, dynamical thresholds for compound-nucleus formation, enhancement in neutron emission prior to fission, and widths of mass and charge distributions in deep-inelastic heavy-ion reactions. 41 refs., 8 figs.
Date: January 1, 1986
Creator: Nix, J.R. & Sierk, A.J.
Partner: UNT Libraries Government Documents Department

Coulomb correlation effects in quasi-one-dimensional conductors

Description: Recent results on the role of electron-electron (e-e) interactions - ''correlation effects'' - in quasi-one-dimensional conductors are reviewed. Within the Peierls-Hubbard model, the consequences of short range (on-site U and nearest neighbor V) e-e interactions for ground state properties, nonlinear excitations, and optical absorption are examined. Techniques include quantum Monte Carlo and weak and strong coupling perturbative arguments. 26 refs., 2 figs.
Date: January 1, 1986
Creator: Campbell, D.K.; Baeriswyl, D. & Mazumdar, S.
Partner: UNT Libraries Government Documents Department

Some effects on the kinetics of muon-catalyzed fusion

Description: Two important stages in the kinetics of muon-catalyzed d-t fusion are discussed: (1) atomic thermalization and hyperfine-state relaxation preceding molecular formation and (2) muon stripping and x-ray production if sticking occurs after nuclear fusion. Thermalization is accurately treated by Monte Carlo simulation. It is shown that thermalization and triplet quenching of the ..cap alpha mu.. atom may not finish before dt..mu.. formation in low-tritium targets, but that epithermal transients are most important in high-tritium targets. A complete kinetic treatment of muon stripping from ..cap alpha mu.. is made using newly calculated stripping (ionization and charge transfer) and inelastic excitation cross sections and explicitly treating the 2s-2p Stark mixing. The calculated values of the sticking probability and K..cap alpha.. ..cap alpha mu.. x-rays per fusion are ..omega../sub s/ = 0.53% (0.59%) and I/sub K..cap alpha..//chi = 0.23% (0.28%) at density phi = 1.2 (0.1) times liquid-hydrogen density. Sensitivities to the various kinetic rates are evaluated, and error bars are estimated.
Date: January 1, 1986
Creator: Cohen, J.S.
Partner: UNT Libraries Government Documents Department

Materials technology applied to nuclear accelerator targets

Description: The continuing requests for both shaped and flat, very low areal density metal foils have led to the development of metallurgical quality, high strength products. Intent of this paper is to show methods of forming structures on various substrates using periodic vapor interruptions, alternating anodes, and mechanical peening to alter otherwise unacceptable grain morphology which both lowers tensile strength and causes high stresses in thin films. The three technologies, physical vapor deposition, electrochemistry, and chemical vapor deposition and their thin film products can benefit from the use of laminate technology and control of grain structure morphology through the use of materials research and technology.
Date: November 10, 1986
Creator: Barthell, B.L.
Partner: UNT Libraries Government Documents Department

Effect of irradiation-induced defects on fusion reactor ceramics

Description: Structural, thermal, and electrical properties critical to performance of ceramics in a fusion environment can be profoundly altered by irradiation effects. Neutron damage may cause swelling, reduction of thermal conductivity, increase in dielectric loss, and either reduction or enhancement of strength depending on the crystal structure and defect content of the material. Absorption of ionizing energy inevitably leads to degradation of insulating properties, but these changes can be reduced by alterations in structural or compositional makeup. Assessment of the irradiation response of candidate ceramics Al/sub 2/O/sub 3/, MgAl/sub 2/O/sub 4/, SiC and Si/sub 3/N/sub 4/ shows that each may find use in advanced fusion devices. The present understanding of irradiation-induced defects in ceramics, while far from complete, nevertheless points the way to methods for developing improved materials for fusion applications.
Date: January 1, 1986
Creator: Clinard, F.W. Jr.
Partner: UNT Libraries Government Documents Department

Off-axis scattering of laser beams using single and multi-Gaussian phase function approximation

Description: Within the small-angle approximation, a multi-Gaussian phase function model provides a new description of the multiple scattering process and leads to improved agreement with experiment data. Future work will be concerned with the combination of small-angle and diffusion approximations in the radiative transfer. This should lead to an improved predictive model of the performance of electroopitcal systems in aerosol-loaded atmospheres. 10 refs., 3 figs.
Date: September 1, 1986
Creator: Zardecki, A. & Gerstl, S.A.W.
Partner: UNT Libraries Government Documents Department

Laser neutralization

Description: Laser photodetachment of the excess electron to neutralize relativistic ions offers many advantages over the more conventional collisional methods using gases or thin foils as the neutralization agents. Probably the two most important advantages of laser photodetachment are the generation of a compact and low divergence beam, and the production of intense neutral beams at very high efficiency (approximately 90%). The high intensities or high current densities of the neutral beam result from the fixed maximum divergence that can be added to the beam by photodetachment of the charge using laser intensity of fixed wavelength and incident angle. The high neutralization efficiency is possible because there is no theoretical maximum to the neutralization efficiency, although higher efficiencies require higher laser powers and, therefore, costs. Additional advantages include focusability of the laser light onto the ion beam to maximize its efficacy. There certainly is no residual gas left in the particle beam path as is typical with gas neutralizers. The photodetachment process leaves the neutral atoms in the ground state so there is no excited state fluorescence to interfere with the subsequent beam sensing. Finally, since the beams to be neutralized are very high powered, for a large range of neutralization efficiencies the neutral beam can be increased more by increasing the power to the laser neutralizer than by adding an equal amount of power to the primary accelerator. 26 figs.
Date: June 17, 1986
Creator: Peterson, O.G.
Partner: UNT Libraries Government Documents Department

Radiographic detection of 100 A thickness variations in 1-. mu. m-thick coatings applied to submillimeter-diameter laser fusion targets

Description: We have developed x-ray radiography to measure thickness variations of coatings on laser fusion targets. Our technique is based on measuring the variation in x-ray transmission through the targets. The simplest targets are hollow glass microshells or microballoons 100 to 500 ..mu..m in diameter, that have several layers of metals or plastics, 1 to 100 ..mu..m thick. Our goal is to examine these opaque coatings for thickness variations as small as 1% or 0.1%, depending on the type of defect. Using contact radiography we have obtained the desired sensitivity for concentric and elliptical defects of 1%. This percentage corresponds to thickness variations as small as 100 A in a 1-..mu..m-thick coating. For warts and dimples, the desired sensitivity is a function of the area of the defect, and we are developing a system to detect 0.1% thickness variations that cover an area 10 ..mu..m by 10 ..mu..m. We must use computer analysis of contact radiographs to measure 1% thickness variations in either concentricity or ellipticity. Because this analysis takes so long on our minicomputer, we preselect the radiographs by looking for defects at the 10% level on a video image analysis system.
Date: January 1, 1986
Creator: Stupin, D.M.
Partner: UNT Libraries Government Documents Department

Comprehensive environmental assessment and response program confirmation and evaluation activities

Description: The US Department of Energy Albuquerque Operations Office (DOE-AL) initiated the Comprehensive Environmental Assessment and Response Program (CEARP) to identify, evaluate, and conduct remedial actions at hazardous waste disposal and contamination sites on the eight nuclear weapons development and production installations under its jurisdiction. The CEARP is being implemented in five phases (Phase 1 - Installation Assessment, Phase 2 - Confirmation, Phase 3 - Technological Assessment, Phase 4 - Remedial Action, and Phase 5 - Compliance and Verification). During Phase 1, regulatory compliance was evaluated and disposal/contamination sites were identified. Phase 2 provides the field data for site characterization, risk assessment, determination of need for corrective action, and evaluation of possible remedial actions at hazardous waste sites. Phase 2 is being conducted in two stages (monitoring plan development/reconnaissance sampling and site characterization/remedial investigation). Problem sites across the DOE-AL complex were prioritized for site characterization and CEARP Phase 2 activities have been initiated.
Date: January 1, 1986
Creator: Martz, M.K.; Rea, K.H.; Vocke, R.W. & Ferenbaugh, R.W.
Partner: UNT Libraries Government Documents Department

Magnetic anisotropy in the U/sub x/Th/sub 1-x/Zn/sub 8. 5/ system

Description: We have investigated the source of the anisotropic susceptibility of UZn/sub 8.5/ by preparing single crystals of U/sub x/Th/sub 1-x/Zn/sub 8.5/ for small x. Preliminary indications are that anisotropic exchange, rather than crystal field effects, are responsible for the anisotropy, but possible impurity contributions to the (anisotropic) susceptibility of the ThZn/sub 8.5/ do not permit a stronger statement. Further measurements for small x show that both the electronic specific heat and the susceptibility at low temperature are strongly enhanced, and that Kondo-like resistivity minima are observed. The enhancements are somewhat reduced in the concentrated system UZn/sub 8.5/.
Date: January 1, 1986
Creator: Willis, J.O.; Fisk, Z.; Aikin, R.M.; McElfresh, M.W.; Thompson, J.D.; Zirngiebl, E. et al.
Partner: UNT Libraries Government Documents Department

High-radiation zone design of the FMIT high-density beam transport

Description: The Fusion Materials Irradiation Test (FMIT) deuteron linac, operating at 35 MeV and 100 mA continuous duty, is expected to spill 3 ..mu..A/m and to lose 10 ..mu..A at specific bending-magnet positions. The major impact of this spill will be felt in the High-Energy Beam Transport (HEBT), where many beam-line components must be maintained. A modular design concept, that uses segmented termination panels remotely located from the modules, is being employed. Radiation-hardened quadrupoles can be opened, clam-shell fashion, to release the water-cooled beam tube r replacement if there is beam damage or lithium contamination from the target. Termination panels contain electrical, water, and instrumentation fittings to service the module, and are positioned to allow room for neutron-absorbing shielding between the beamline and the panel. The modular construction allows laboratory prealignment and check-out of all components on a structural carriage and is adaptable to supporting gamma shields. Proper choice of beam tube materials is essential for controlling activation caused by beam spill.
Date: March 1, 1981
Creator: Creek, K.O.; Liska, D.J.; King, J.D.; Cole, T.R.; Cimabue, A.G.; Robeson, L.P. et al.
Partner: UNT Libraries Government Documents Department

The role of the DOE weapons laboratories in a changing national security environment: CNSS papers No. 8, April 1988

Description: The contributions of the Department of Energy (DOE) nuclear weapons laboratories to the nation's security are reviewed in testimony before the Subcommittee on Procurement and Military Nuclear Systems of the House Armed Services Committee. Also presented are contributions that technology will make in maintaining the strategic balance through deterrence, treaty verification, and a sound nuclear weapons complex as the nation prepares for significant arms control initiatives. The DOE nuclear weapons laboratories can contribute to the broader context of national security, one that recognizes that military strength can be maintained over the long term only if it is built upon the foundations of economic strength and energy security. 9 refs.
Date: January 1, 1988
Creator: Hecker, S.S.
Partner: UNT Libraries Government Documents Department

High spatial resolution in x-ray fluorescence

Description: The design of diffracting crystals for use in x-ray fluorescence spectrometers is discussed. Characteristics of the Johan and Johansson geometries are discussed and intensity profiles are developed. If the diffraction line has a finite width, concentration gradients will not be faithfully reproduced by gradients in the signal as the sample is scanned. Boundary effects for four types of concentration gradient are presented; as step function, linear gradients, exponential gradient, and Gaussian gradient. (DWL) 13 refs., 8 figs.
Date: January 1, 1986
Creator: Zahrt, J.D.
Partner: UNT Libraries Government Documents Department