To gain insight on the controlling mechanisms for VOC transport in porous media, the relations among sorbent properties, sorption equilibrium and intraparticle diffusion processes were studied at the level of individual sorbent particles and laboratory columns for soil and activated carbon systems. Transport and sorption of VOCs and water vapor were first elucidated within individual dry soil mineral grains. Soil properties, sorption capacity, and sorption rates were measured for 3 test soils; results suggest that the soil grains are porous, while the sorption isotherms are nonlinear and adsorption-desorption rates are slow and asymmetric. An intragranular pore diffusion model coupled with the nonlinear Freundlich isotherm was developed to describe the sorption kinetic curves. Transport of benzene and water vapor within peat was studied; partitioning and sorption kinetics were determined with an electrobalance. A dual diffusion model was developed. Transport of benzene in dry and moist soil columns was studied, followed by gaseous transport and sorption in activated carbon. The pore diffusion model provides good fits to sorption kinetics for VOCs to soil and VOC to granular activated carbon and activated carbon fibers. Results of this research indicate that: Intraparticle diffusion along with a nonlinea sorption isotherm are responsible for the slow, …

Release rates of 15 radionuclides from waste packages expected to result from partitioning and transmutation of Light-Water Reactor (LWR) and Actinide-Burning Liquid-Metal Reactor (ALMR) spent fuel are calculated and compared to release rates from standard LWR spent fuel packages. The release rates are input to a model for radionuclide transport from the proposed geologic repository at Yucca Mountain to the water table. Discharge rates at the water table are calculated and used in a model for transport to the accessible environment, defined to be five kilometers from the repository edge. Concentrations and dose rates at the accessible environment from spent fuel and wastes from reprocessing, with partitioning and transmutation, are calculated. Partitioning and transmutation of LWR and ALMR spent fuel reduces the inventories of uranium, neptunium, plutonium, americium and curium in the high-level waste by factors of 40 to 500. However, because release rates of all of the actinides except curium are limited by solubility and are independent of package inventory, they are not reduced correspondingly. Only for curium is the repository release rate much lower for reprocessing wastes.

{sup 129}Xe NMR is potentially useful for the investigation of material surfaces, but has been limited to high surface area samples in which sufficient xenon can be loaded to achieve acceptable signal to noise ratios. In Chapter 2 conventional {sup 129}Xe NMR is used to study a high surface area polymer, a catalyst, and a confined liquid crystal to determine the topology of these systems. Further information about the spatial proximity of different sites of the catalyst and liquid crystal systems is determined through two dimensional exchange NMR in Chapter 3. Lower surface area systems may be investigated with spin-polarized xenon, which may be achieved through optical pumping and spin exchange. Optically polarized xenon can be up to 10{sup 5} times more sensitive than thermally polarized xenon. In Chapter 4 highly polarized xenon is used to examine the surface of poly(acrylonitrile) and the formation of xenon clathrate hydrates. An attractive use of polarized xenon is as a magnetization source in cross polarization experiments. Cross polarization from adsorbed polarized xenon may allow detection of surface nuclei with drastic enhancements. A non-selective low field thermal mixing technique is used to enhance the {sup 13}C signal of CO{sub 2} of xenon occluded in …

The American system of nuclear weapons research and development was conceived and developed not as a result of technological determinism, but by a number of individual architects who promoted the growth of this large technologically-based complex. While some of the technological artifacts of this system, such as the fission weapons used in World War II, have been the subject of many historical studies, their technical successors--fusion (or hydrogen) devices--are representative of the largely unstudied highly secret realms of nuclear weapons science and engineering. In the postwar period a small number of Los Alamos Scientific Laboratory's staff and affiliates were responsible for theoretical work on fusion weapons, yet the program was subject to both the provisions and constraints of the US Atomic Energy Commission, of which Los Alamos was a part. The Commission leadership's struggle to establish a mission for its network of laboratories, least of all to keep them operating, affected Los Alamos's leaders' decisions as to the course of weapons design and development projects. Adapting Thomas P. Hughes's ''large technological systems'' thesis, I focus on the technical, social, political, and human problems that nuclear weapons scientists faced while pursuing the thermonuclear project, demonstrating why the early American thermonuclear bomb …

NMR spectroscopy is ideal for studying weak interactions (formation enthalpy {le}20 kcal/mol) in solution. The metallocene bis(pentamethylcyclopentadienyl)ytterbium, Cp*{sub 2}Yb, is ideal for this purpose. cis-P{sub 2}PtH{sub 2}complexes (P = phosphine) were used to produce slow-exchange Cp*{sub 2}YbL adducts for NMR study. Reversible formation of (P{sub 2}PtH){sub 2} complexes from cis-P{sub 2}PtH{sub 2} complexes were also studied, followed by interactions of Cp*{sub 2}Yb with phosphines, R{sub 3}PX complexes. A NMR study was done on the interactions of Cp*{sub 2}Yb with H{sub 2}, CH{sub 4}, Xe, CO, silanes, stannanes, C{sub 6}H{sub 6}, and toluene.

Smooth particle methods are relatively new methods for simulating solid and fluid flows through they have a 20-year history of solving complex hydrodynamic problems in astrophysics, such as colliding planets and stars, for which correct answers are unknown. The results presented in this thesis evaluate the adaptability or fitness of the method for typical hydrocode production problems. For finite hydrodynamic systems, boundary conditions are important. A reflective boundary condition with image particles is a good way to prevent a density anomaly at the boundary and to keep the fluxes continuous there. Boundary values of temperature and velocity can be separately controlled. The gradient algorithm, based on differentiating the smooth particle expression for (u{rho}) and (T{rho}), does not show numerical instabilities for the stress tensor and heat flux vector quantities which require second derivatives in space when Fourier`s heat-flow law and Newton`s viscous force law are used. Smooth particle methods show an interesting parallel linking to them to molecular dynamics. For the inviscid Euler equation, with an isentropic ideal gas equation of state, the smooth particle algorithm generates trajectories isomorphic to those generated by molecular dynamics. The shear moduli were evaluated based on molecular dynamics calculations for the three weighting functions, …

The low temperature and flux dependent growth of ultrathin Ag films on the Si(111)7x7 surface is studied with Reflection High-Energy Electron Diffraction (RHEED). The grazing incidence geometry of RHEED allows for an incident molecular beam normal to the surface, and makes it an ideal surface probe for studying ultrathin film growth in real time. Short-lived oscillations in the diffracted intensity are observed during Ag deposition at 150 K, indicating quasi-layer-by-layer growth mediated by adatom mobility. When the 150 K growth is performed over a wide range of deposition rates F, the peak intensity is observed to scale, i.e. I(Ft) depends only on the total amount deposited, which implies thermally activated diffusion is absent at 150 K. Scaling is not obeyed at higher temperatures (T{ge}473 K) for the growth of the {radical}3{times}{radical}3 R30{degrees} ({radical}3) superstructure. Testing for scaling of the diffracted intensity constitutes a new experimental method which can be applied generally to determine if thermal diffusion is active at a particular temperature. Scaling is consistent with a constant diffusion length R{sub 0}, independent of substrate temperature and deposition rate. The presence of a non-thermal diffusion mechanism (responsible for the constant diffusion length R{sub 0}) is confirmed by monitoring the flux …

Elastic wave propagation in highly heterogeneous media is investigated and theoretical calculations and field measurements are presented. In the first part the dynamic composite elastic medium (DYCEM) theory is derived for one-dimensional stratified media. A self-consistent method using the scattering functions of the individual layers is formulated, which allows the calculation of phase velocity, attenuation and waveform. In the second part the DYCEM theory has been generalized for three-dimensional inclusions. The specific case of spherical inclusions is calculated with the exact scattering functions and compared with several low frequency approximations. In the third part log and VSP data of partially water saturated tuffs in the Yucca Mountain region of Nevada are analyzed. The anomalous slow seismic velocities can be explained by combining self-consistent theories for pores and cracks. The fourth part analyzes an air injection experiment in a shallow fractured limestone, which has shown large effects on the amplitude, but small effects on the travel time of the transmitted seismic waves. The large amplitude decrease during the experiment is mainly due to the impedance contrast between the small velocities of gas-water mixtures inside the fracture and the formation. The slow velocities inside the fracture allow an estimation of aperture and …

Rayleigh-Schroedinger perturbation theory is an effective and popular tool for describing low-lying vibrational and rotational states of molecules. This method, in conjunction with ab initio techniques for computation of electronic potential energy surfaces, can be used to calculate first-principles molecular vibrational-rotational energies to successive orders of approximation. Because of mathematical complexities, however, such perturbation calculations are rarely extended beyond the second order of approximation, although recent work by Herbert has provided a formula for the nth-order energy correction. This report extends that work and furnishes the remaining theoretical details (including a general formula for the Rayleigh-Schroedinger expansion coefficients) necessary for calculation of energy corrections to arbitrary order. The commercial computer algebra software Mathematica is employed to perform the prohibitively tedious symbolic manipulations necessary for derivation of generalized energy formulae in terms of universal constants, molecular constants, and quantum numbers. As a pedagogical example, a Hamiltonian operator tailored specifically to diatomic molecules is derived, and the perturbation formulae obtained from this Hamiltonian are evaluated for a number of such molecules. This work provides a foundation for future analyses of polyatomic molecules, since it demonstrates that arbitrary-order perturbation theory can successfully be applied with the aid of commercially available computer algebra software.

Polarized Z{sup 0}`s from e{sup +}e{sup {minus}} collisions at the SLAC Linear Collider (SLC) have been used to determine the asymmetry parameters A{sub e}, A{sub {mu}} and A{sub {tau}} from the leptonic decay channels. This is the first direct measurement of A{sub {mu}}. The data have been gathered by the SLC Large Detector (SLD) with the electron polarization averaging 63% during the 1993 data taking period and 77% in 1994-95. A maximum likelihood procedure as well as cross section asymmetries was used to measure the asymmetry parameters from the differential cross sections for equal luminosities of left- and right-handed electron beams. The polarization-dependent muon-pair distributions give A{sub {mu}} = 0.102 {+-}0.034 and the tau-pairs give A{sub {tau}} = 0.195 {+-}0.034. The initial state electronic couplings in all three leptonic channels as well as the final state angular distribution in the e{sup +}e{sup {minus}} final state measure A{sub e} to be A{sub e} = 0.152{+-}0.012. Assuming lepton universality and defining a global leptonic asymmetry parameter A{sub e-{mu}-{tau}} = 0.151{+-}0.011. This global leptonic asymmetry value translates directly into sin{sup 2}{theta}{sub W}{sup eff}=0.2310{+-}0.0014 at the Z{sup 0} pole.

This thesis studies several tearing mode problems from both theoretical and experimental points of view. A major part of this thesis is to demonstrate that Electron Cyclotron Emission (ECE) is an excellent diagnostic for studying an MHD mode structure and its properties in a tokamak plasma. It is shown that an MHD mode can be detected from the electron temperature fluctuations measured by ECE. The amplitude and phase profiles of the fluctuations contain detailed information about the mode structure. The ECE fluctuation phase profile indicates the magnetic island deformation due to the combination of sheared flow and viscosity. A model is presented to relate qualitatively the observed phase gradient to the local magnetic field, flow velocity shear and viscosity in a 2D slab geometry, using an ideal Ohm`s law and the plasma momentum equation including flow and viscosity. Numerical solution of the resultant Grad-Shafranov-like equation describing the deformed island shows that the experimentally observed value of the phase gradient can be obtained under realistic parameters for the shear in the flow velocity and viscosity. A new approach to the tearing mode stability boundary and saturation level is also presented.

A postulated severe loss of coolant accident in a nuclear reactor can lead to significant core damage due to residual heat generation. Subsequently, melted core materials (i.e.; corium) could migrate downward and impinge upon the lower head of the reactor pressure vessel (RPV). During this relocation, the complexity of the reactor structure could segregate the molten corium into various flow paths. A perforated flow plate could readily provide the mechanism to segregate the molten corium. The resulting small (a few cm) diameter melt streams, driven by gravity, could then penetrate the remaining coolant in the RPV and cause any of the following events: impingement of the high temperature melt streams on the lower head could breach the RPV; re-agglomeration of the corium melt on the lower head could influence the coolability of the debris bed; {open_quotes}pre-mixing{close_quotes} of the melt streams with the coolant could lead to a vapor explosion; or, sufficient quenching of the melt streams by the coolant could produce a stabilized debris bed. An overview of the thermo-science issues related to core-melt accidents is presented by Theofanous. Thus, insight into the melt stream breakup mechanisms (i.e.; interfacial conditions, fragmentation, and geometric spacing) during the melt-coolant interactions is necessary …

Net proton (proton minus antiproton) and negative charge hadron spectra (h-) from central Pb+Pb collisions at 158 GeV per nucleon at the CERN Super Proton Synchrotron were measured and compared to spectra from central collisions of the lighter S+S system. Net baryon distributions were derived from those of net protons and net lambdas. Stopping, or rapidity shift with respect to the beam, of net protons and net baryons increase with system size. The mean transverse momentum &60;pT&62; of net protons also increase with system size. The h- rapidity density scales with the number of participant nucleons for nuclear collisions, where their &60;pT&62; is independent of system size. The &60;pT&62; dependence upon particle mass and system size is consistent with larger transverse flow velocity at midrapidity for central collisions of Pb+Pb compared to that of S+S.

The fundamental motivation for the research presented in this dissertation was the need to development a more accurate prediction method for characterization of mixed radiation fields around medical electron accelerators (MEAs). Specifically, a model is developed for simulation of neutron and other particle production from photonuclear reactions and incorporated in the Monte Carlo N-Particle (MCNP) radiation transport code. This extension of the capability within the MCNP code provides for the more accurate assessment of the mixed radiation fields. The Nuclear Theory and Applications group of the Los Alamos National Laboratory has recently provided first-of-a-kind evaluated photonuclear data for a select group of isotopes. These data provide the reaction probabilities as functions of incident photon energy with angular and energy distribution information for all reaction products. The availability of these data is the cornerstone of the new methodology for state-of-the-art mutually coupled photon-neutron transport simulations. The dissertation includes details of the model development and implementation necessary to use the new photonuclear data within MCNP simulations. A new data format has been developed to include tabular photonuclear data. Data are processed from the Evaluated Nuclear Data Format (ENDF) to the new class ''u'' A Compact ENDF (ACE) format using a standalone processing …

None

This thesis reports the measurement of the inclusive charged particle (h{sup +} + h{sup -}) p{perpendicular} spectra for 1.7 < p{perpendicular} < 6 GeV/c at midrapidity (|{eta}| < 0.5) as a function of various centrality classes in Au+Au collisions at {radical}s{sub NN} = 130 GeV. Hadron suppression is observed relative to both scaled NN and peripheral Au+Au reference data, possibly indicating non-Abelian radiative energy loss in a hot, dense medium.

The availability of high power, spectrally and spatially coherent soft x-rays (SXR) would facilitate a wide variety of experiments as this energy region covers the primary resonances of many magnetic and biological materials. Specifically, there are the carbon and oxygen K-edges that are critical for biological imaging in the water window and the L-edges of iron, nickel, and cobalt for which imaging and scattering studies can be performed. A new coherent soft X-ray branchline at the Advanced Light Source has begun operation (beamline 12.0.2). Using the third harmonic from an 8 cm period undulator, this branch delivers coherent soft x-rays with photon energies ranging from 200eV to 1keV. This branchline is composed of two sub-branches one at 14X demagnification and the other 8X demagnification. The former is optimized for use at 500eV and the latter at 800eV. Here the expected power from the third harmonic of this undulator and the beamline design and characterization is presented. The characterization includes measurements on available photon flux as well as a series of double pinhole experiments to determine the coherence factor with respect to transverse distance. The first high quality Airy patterns at SXR wavelengths are created with this new beamline. The operation …

The MiniBooNE experiment was designed to perform a search for {nu}{sub {mu}} {yields} {nu}{sub e} oscillations in a region of {Delta}m{sup 2} and sin{sup 2} 2{theta} very different from that allowed by standard, three-neutrino oscillations, as determined by solar and atmospheric neutrino experiments. This search was motivated by the LSND experimental observation of an excess of {bar {nu}}{sub e} events in a {bar {nu}}{sub {mu}} beam which was found compatible with two-neutrino oscillations at {Delta}m{sup 2} {approx} 1 eV{sup 2} and sin{sup 2} 2{theta} < 1%. If confirmed, such oscillation signature could be attributed to the existence of a light, mostly-sterile neutrino, containing small admixtures of weak neutrino eigenstates. In addition to a search for {nu}{sub {mu}} {yields} {nu}{sub e} oscillations, MiniBooNE has also performed a search for {bar {nu}}{sub {mu}} {yields} {bar {nu}}{sub e} oscillations, which provides a test of the LSND two-neutrino oscillation interpretation that is independent of CP or CPT violation assumptions. This dissertation presents the MiniBooNE {nu}{sub {mu}} {yields} {nu}{sub e} and {bar {nu}}{sub {mu}} {yields} {bar {nu}}{sub e} analyses and results, with emphasis on the latter. While the neutrino search excludes the two-neutrino oscillation interpretation of LSND at 98% C.L., the antineutrino search shows an …

The use of high rate anodic dissolution (electrochemical machining) for shaping titanium carbide, zirconium carbide, titanium boride and zirconium boride has been investigated in 2N potassium nitrate and 3N sodium chloride under current densities ranging from 20 to 120 A/cm{sup 2} (corresponding to cutting rates of 0.3 to 1.8 mm/min). The dissolution stoichiometry for all these materials is independent of the current density in the range 20 to 120 A/cm{sup 2}. Both titanium and zirconium appear to dissolve in the +4 state, boron in the +3 state and the weight loss measurements indicate that carbon is oxidized to CO and CO{sub 2}. The current voltage curves permit to establish that, over the entire current density and flow range investigated, dissolution occurs in the transpassive state. The surface roughness obtained on TiC and ZrC is within 3-5 {micro}m and is independent of current density, applied voltage or flow rate.

The CP violating phase {beta}{sub s}{sup J/{psi}{phi}} is measured in decays of B{sub s}{sup 0} {yields} J/{psi}{phi}. This measurement uses 5.2 fb{sup -1} of data collected in {radical}s = 1.96 TeV p{bar p} collisions at the Fermilab Tevatron with the CDF Run-II detector. CP violation in the B{sub s}{sup 0}-{bar B}{sub s}{sup 0} system is predicted to be very small in the Standard Model. However, several theories beyond the Standard Model allow enhancements to this quantity by heavier, New Physics particles entering second order weak mixing box diagrams. Previous measurements have hinted at a deviation from the Standard Model expectation value for {beta}{sub s}{sup J/{psi}{phi}} with a significance of approximately 2{sigma}. The measurement described in this thesis uses the highest statistics sample available to date in the B{sub s}{sup 0} {yields} J/{psi}{phi} decay channel, where J/{psi} {yields} {mu}{sup +}{mu}{sup -} and {phi} {yields} K{sup +}K{sup -}. Furthermore, it contains several improvements over previous analyses, such as enhanced signal selection, fully calibrated particle ID and flavour tagging, and the inclusion of an additional decay component in the likelihood function. The added decay component considers S-wave states of KK pairs in the B{sub s}{sup 0} {yields} J/{psi} K{sup +}K{sup -} channel. The …

None

Mathematical descriptions of an excited state multilevel system are developed to include progressively the effects of coherent coupling, feeding, decay and relaxation, and the expressions are illustrated with several pulse coherence experiments utilizing zero field optically detected magnetic resonance of excited triplet states. A new method is described in which the time development of the coherent components in a multilevel system is monitored by using an observable that can measure only relative populations between the levels. The method is illustrated. By treating a coherently driven excited state system as two levels in contact with a population reservoir, exact expressions are obtained for both transient and steady-state behavior in the presence of transverse and spin lattice relaxation, constant incoherent pumping, spontaneous emission between the two levels, and also decay back into the reservoir. The general mathematical development is applied specifically to zero field microwave phosphorescence double resonance. Experimental methods and apparatus are discussed in detail and results of optically detected transient mutations, spin echoes, and Fourier transform spectroscopy are presented. (26 figs, 220 refs) (auth)

The effect of free-particle collisions in simple ''knockout'' reactions of the form (a,aN) and in more complex nuclear reactions of the form (a,X) was investigated by using protons and pions. Cross sections for the $sup 48$Ti(p,2p)$sup 47$Sc and the $sup 74$Ge(p,2p)$sup 73$Ga reactions were measured from 0.3 to 4.6 GeV incident energy. The results indicate a rise in (p,2p) cross section for each reaction of about (25 +- 3) percent between the energies 0.3 and 1.0 GeV, and are correlated to a large increase in the total free-particle pp scattering cross sections over the same energy region. Results are compared to previous (p,2p) excitation functions in the GeV energy region and to (p,2p) cross section calculations based on a Monte Carlo intranuclear cascade-evaporation model. Cross section measurements for ($pi$/sup +-/, $pi$N) and other more complex pion-induced spallation reactions were measured for the light target nuclei $sup 14$N, $sup 16$O, and $sup 19$F from 45 to 550 MeV incident pion energy. These measurements indicate a broad peak in the excitation functions for both ($pi$,$pi$N) and ($pi$,X) reactions near 180 MeV incident energy. This corresponds to the large resonances observed in the free-particle $pi$$sup +$p and $pi$$sup -$p cross sections at the …

A search for the Technicolor processes p{bar p} {yields} {rho}{sub T}{sup {+-}} {yields} W{sup {+-}}{pi}{sub T}{sup 0} {yields} {mu}{nu}b{bar b} and p{bar p} {yields} {rho}{sub T}{sup 0} {yields} W{sup {+-}}{pi}{sub T}{sup {+-}} {yields} {mu}{nu}b{bar c} is conducted at the D0 detector. Selection requirements are individually optimized for each of twenty mass hypotheses by means of a random grid search. No excess is seen in a 291 pb{sup -1} data set and 95% confidence level upper limits are set on the Technicolor production cross section. The mass combinations M{sub {rho}} = 195 GeV/c{sup 2}, M{sub {pi}} = 100 GeV/c{sup 2} and M{sub {rho}} = 200 GeV/c{sup 2}, M{sub {pi}} = 105 GeV/c{sup 2} are excluded for the choice of the Technicolor scale parameter M{sub V} = 500 GeV.