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Penetrating radiation impact on NIF final optic components

Description: Goal of the National Ignition Facility (NIF) is to achieve thermonuclear ignition in a laboratory environment in inertial confinement fusion (ICF). This will enable NIF to service the DOE stockpile stewardship management program, inertial fusion energy goals, and advance scientific frontiers. All of these applications will make use of the extreme conditions that the facility will create in the target chamber. In the case of a prospected 20 MJ yield scenario, NIF will produce 10{sup 19} neutrons with DT fusion 14 MeV energy per neutron. There will also be high-energy x rays as well as solid, liquid, and gaseous target debris produced either directly or indirectly by the inertial confinement fusion process. A critical design issue is the protection of the final optical components as well as sophisticated target diagnostics in such a harsh environment.
Date: October 15, 1996
Creator: Marshall, C.D.; Speth, J.A.; DeLoach, L.D. & Payne, S.A.
Partner: UNT Libraries Government Documents Department

Search for top and bottom squarks

Description: Searches for the lightest scalar top quark {bar t}{sub 1} and scalar bottom quark {bar b}{sub 1} performed at LEP2 with a center-of-mass energy of up to {radical}s = 209 GeV and at Tevatron using data collected at {radical}s = 1.8 TeV during Run I and at {radical}s = 1.96 TeV during Run II, are discussed. Different possible decay modes were considered and no evidence for any such signal was observed. Exclusion limits were extracted.
Date: October 15, 2003
Creator: Rott, C.
Partner: UNT Libraries Government Documents Department

The atmospheric neutrino flavor ratio in Soudan 2.

Description: We have measured the flavor ratio of ratios (R) in atmospheric neutrino interactions using a 1.52 kton-year exposure of Soudan 2. We find R = 0.67 {+-} 0.15{sub {minus}0.06}{sup +0.04}. This value is about 2{sigma} from the expected value of 1.0 and is consistent with the anomalous ratios measured by the Kamiokande and IMB experiments. We note that since our acceptance matrix is different from those of the water Cherenkov experiments we would not expect to measure the same value of R, unless R=1.
Date: October 15, 1997
Creator: Goodman, M.
Partner: UNT Libraries Government Documents Department

First Run II b physics results from the Tevatron

Description: The current status of Run II at the Tevatron is covered. Upgrades of both the CDF and D0 detectors are presented, along with many illustrations of the performance and potential for significant physics measurements.
Date: October 15, 2003
Creator: Blocker, C.
Partner: UNT Libraries Government Documents Department

An application of performance goal based method for the design and evaluation of structures

Description: This paper describes an application of the U.S. Department of Energy`s (DOE) performance goal based method for the design and evaluation of structures, systems, and components (SSCS) at Fluor Daniel Hanford, Inc. (FDH). The philosophy on which DOE`s method is based has been employed to construct a graded approach to the minimum structural design and evaluation criteriz@ used at the DOE Hanford Site that complies with the DOE Order 54E;0.28, Natural Phenomena Hazards Mitigation. The FDH structural design and evaluation criteria applies to both nuclear and non-nuclear SSCs that are not covered by a reactor safety analysis report.
Date: October 15, 1996
Creator: Conrads, T.J.
Partner: UNT Libraries Government Documents Department

Theoretical aspects of top quark production at hadron collider

Description: We summarize our calculation of the total cross section for top quark production at hadron colliders within the context of perturbative quantum chromodynamics, including resummation of the effects of initial-state soft gluon radiation to all orders in the strong coupling strength.
Date: October 15, 1996
Creator: Berger, E.L. & Contopanagos, H.
Partner: UNT Libraries Government Documents Department

Designs Studies of Low-Aspect Ratio Quasi-Omnigenous Stellarators

Description: Significant progress has been made in the development of new modest-size compact stellarator devices that could test optimization principles for the design of a more attractive reactor. These are 3 and 4 field period low-aspect-ratio quasi-omnigenous (QO) stellarators based on an optimization method that targets improved confinement, stability, ease of coil design, low-aspect-ratio, and low bootstrap current.
Date: October 15, 1998
Creator: Batchelor, D.B.; Carreras, B.A.; Hirshman, S.P.; Lynch, V.E.; Sanchez, R.; Spong, D.A. et al.
Partner: UNT Libraries Government Documents Department

A prototype distributed object-oriented architecture for image-based automatic laser alignment

Description: Designing a computer control system for the National Ignition Facility (NIF) is a complex undertaking because of the system`s large size and its distributed nature. The controls team is addressing that complexity by adopting the object-oriented programming paradigm, designing reusable software frameworks, and using the Common Object Request Broker Architecture (CORBA) for distribution. A prototype system for image-based automatic laser alignment has been developed to evaluate and gain experience with CORBA and OOP in a small distributed system. The prototype is also important in evaluating alignment concepts, image processing techniques, speed and accuracy of automatic alignment objectives for the NIF, and control hardware for aligment devices. The prototype system has met its inital objectives and provides a basis for continued development.
Date: October 15, 1996
Creator: Stout, E.A.; Kamm, V.J.M.; Spann, J.M. & Van Arsdall, P.J.
Partner: UNT Libraries Government Documents Department

Cryogenic D-T fuel layers formed in 1mm spheres by beta-layering

Description: Solid D-T fuel smoothly layered on the interior of spherical capsules is required for all inertial confinement fusion ignition target designs. One process for forming these layers, beta-layering, has been studied in surrogate geometries such as open cylinders or tori to allow accurate characterization of the DT surfaces. We present the first results from beta layering in 1 mm spherical containers, such as will be used in upcoming Omega experiments. These results are also directly relevant to ignition capsules for the National Ignition Facility. We find that layers can form with roughness as small as 1.2 microns rms, and that results are strongly dependent upon freezing rate as well as layer thickness.
Date: October 15, 1998
Creator: Bernat, T P; Burmann, J; Collins, G W; Kozioziemski, B; Mapoles, E R; Pipes, J et al.
Partner: UNT Libraries Government Documents Department

The inclusive jet cross section in p pbar collisions at {radical}s = 1.8 TeV using the kT algorithm

Description: We present a preliminary measurement of the central inclusive jet cross section using a successive combination algorithm based on relative transverse momenta (k{perpendicular}) for jet reconstruction. We analyze a 87.3 pb{sup -1} data sample collected by the D0 detector at the Fermilab Tevatron p{bar p} Collider during 1994-1995. The cross section, reported as a function of transverse momentum (p{sub T} > 60 GeV) in the central region of pseudo-rapidity (|{eta}| < 0.5), is in reasonable agreement with next-to-leading order QCD predictions. This is the first jet production measurement in a hadron collider using a successive combination type of jet algorithm.
Date: October 15, 2001
Creator: al., V. M. Abazov et
Partner: UNT Libraries Government Documents Department

Meson interferometry and the quest for quark-gluon matter

Description: We point out what we may learn from the investigation of identical two-particle interferometry in ultrarelativistic heavy ion collisions if we assume a particular model scenario by the formation of a thermalized quark-gluon plasma hadronizing via a first-order phase transition to an interacting hadron gas. The bulk properties of the two-pion correlation functions are dominated by these late and soft resonance gas rescattering processes. However, we show that kaons at large transverse momenta have several advantages and a bigger sensitivity to the QCD phase transition parameters.
Date: October 15, 2001
Creator: Soff, Sven
Partner: UNT Libraries Government Documents Department

Influence of dopants on defect formation in GaN

Description: Influence of p-dopants (Mg and Be) on the structure of GaN has been studied using Transmission Electron Microscopy (TEM). Bulk GaN:Mg and GaN:Be crystals grown by a high pressure and high temperature process and GaN:Mg grown by metal-organic chemical-vapor deposition (MOCVD) have been studied. Structural dependence on growth polarity was observed in the bulk crystals. Spontaneous ordering in bulk GaN:Mg on c-plane (formation of Mg-rich planar defects with characteristics of inversion domains) was observed for growth in the N to Ga polar direction (N polarity). On the opposite site of the crystal (growth in the Ga to N polar direction) Mg-rich pyramidal defects empty inside (pinholes) were observed. Both these defects were also observed in MOCVD grown crystals. Pyramidal defects were also observed in the bulk GaN:Be crystals.
Date: October 15, 2001
Creator: Liliental-Weber, Z.; Jasinski, J.; Benamara, M.; Grzegory, I.; Porowski, S.; Lampert, D.J.H. et al.
Partner: UNT Libraries Government Documents Department

Recent developments in fissile material exemptions for shipping packages

Description: This paper discusses the regulatory exemptions for shipping packages that contain limited amounts of fissile material and concerns that have arisen over the adequacy of these regulations. The results of an ongoing review of these exemptions by the various regulatory agencies will be presented in the session.
Date: October 15, 1996
Creator: Sheaffer, M. K.; Liu, Y. Y.; Wangler, M. E.; Keeton, S. C. & Fischer, L. E.
Partner: UNT Libraries Government Documents Department

Linear stability of an accelerated wire array

Description: The linear stability of an array of a large number of thin wires is considered. The wires form a cylindrical surface which is accelerated towards the axis under the action of a current excited in the array by an external source. General equations governing stability of this system are derived and a complete classification of all the modes present in such a system is presented. In agreement with an earlier analysis by Felber and Rostoker, it is shown that there exist two types of modes: medial modes, in which the wires experience deformation in the rz plane, and lateral modes, in which only a purely azimuthal deformation is present. For a given axial wave number k, the maximum growth rate for medial perturbations corresponds to a mode in which all the wires move �in phase� (an analog of an axisymmetric mode for a continuous cylindrical shell), whereas for the lateral perturbations the maximum growth rate corresponds to the opposite displacements of the neighboring wires. Numerical analysis of a dispersion relation for a broad range of modes is presented: Some limiting cases are discussed. In particular, it is shown that a traditional k�� scaling holds until surprisingly high wave numbers, even exceeding the inverse inter- wire distance. In the limit of long-wavelength perturbations, a model of a continuous shell becomes valid; the presence of the wires manifests itself in this model by a strong anisotropy of electrical conductivity, high along the wires and vanishing across the wires. The resulting modes differ considerably from the modes of a thin perfectly conducting shell. In particular, a new mode of �zonal flows� is identified.
Date: October 15, 1998
Creator: Hammer, J H & Ryutov, D D
Partner: UNT Libraries Government Documents Department

Back Contact Effects on the Electro-Optical Properties of CdTe/CdS Solar Cells

Description: Studies of junction photoluminescence (PL) in CdTe/CdS solar cells reveal that back-contact application produces a dramatic qualitative change in the junction picosecond-PL spectrum. Prior to contact application, the spectrum has two peaks at energies of 1.501 eV and 1.457 eV, corresponding to recombination in regions of CdTeS alloy with 2% and 12% sulfur content, respectively. After contact application, the spectrum consists of a single broad peak at 1.48 eV. Previous studies have shown that the nitric-phosphoric (NP) etch used in the contact procedure produces a layer of elemental tellurium (Te) on the CdTe surface. We postulate that the change in the near-junction PL spectrum is caused by a grain-boundary field effect due to perturbations of the grain-boundary conductivity and Fermi level.
Date: October 15, 1998
Creator: Levi, D. H.; Albin, D. S.; Gessert, T. A. (National Renewable Energy Laboratory) & Woods, L. M. (Department of Electrical Engineering, Colorado State University, Ft. Collins, CO)
Partner: UNT Libraries Government Documents Department

Grain and burnup dependence of spent fuel oxidation: geological repository impact

Description: Further refinements to the oxidation model of Stout et al. have been made. The present model incorporates the burnup dependence of the oxidation rate in addition to an allowance for a distribution of grain sizes. The model was tested by comparing the model results with the oxidation histories of spent fuel samples oxidized in Thermogravimetric Analysis (TGA) or Oven Dry-Bath (ODB) experiments. The comparison between the experimental and model results are remarkably close and confirm the assumption that grain-size distributions and activation energies are the important parameters to predicting oxidation behavior. The burnup dependence of the activation energy was shown to have a greater effect than decreasing the effective grain size in suppressing the rate of the reaction U{sub 4}O{sub 9}(rightwards arrow)U{sub 3} O{sub 4}. Model results predict that U{sub 3}O{sub 8} formation of spent fuels exposed to oxygen will be suppressed even for high burnup fuels that have undergone restructuring in the rim region, provided the repository temperature is kept sufficient.
Date: October 15, 1998
Creator: Hanson, B. D.; Kansa, E. J. & Stoot, R.B.
Partner: UNT Libraries Government Documents Department

Experimental Demonstration of Guiding and Bending of Electromagnetic Waves in a Photonic Crystal

Description: The routing and interconnection of optical signals through narrow channels and around sharp corners is important for large-scale all-optical circuit applications. A recent computational result suggests that photonic crystals may offer a novel way of achieving this goal by providing a mechanism for guiding light that is fundamentally different from traditional index guiding. Waveguiding in a photonic crystal, and near 100% transmission of electromagnetic waves around sharp 90o corners were observed experimentally. Bend- ing radii were made smaller than one wavelength.
Date: October 15, 1998
Creator: Chow, E.; Hietala, .; Joannopoulos, J.D.; Lin, S. & Villeneuve, P.R.
Partner: UNT Libraries Government Documents Department

Overview of the Target Systems for the Spallation Neutron Source

Description: The technologies that are being utilized to design and build the target systems for a state-of-the-art accelerator- based neutron source, the Spallation Neutron Source (SNS), are discussed. Emphasis is given to the technology issues that present the greatest challenges. The present facility configuration, ongoing analysis, and planned research and development program are also described.
Date: October 15, 1998
Creator: Gabriel, T.A.; Haines, J.R. & McManamy, T.J.
Partner: UNT Libraries Government Documents Department

Dynamic Fiber Optic Sensors Under Intense Radioactive Environments

Description: A liquid mercury target will be used as the neutron source for the proposed Spallation Neutron Source facility. This target is subjected to bombardment by short-pulse, high-energy proton beams. The intense thermal loads caused by interaction of the pulsed proton beam with the mercury create an enormous rate of temperature rise ({approximately}10{sup 7} K/s) during a very brief beam pulse ({approximately } 0.5 {micro}s). The resulting pressure waves in the mercury will interact with the walls of the mercury target and may lead to large stresses. To gain confidence in the mercury target design concept and to benchmark the computer design codes, we tested various electrical and optical sensors for measuring the transient strains on the walls of a mercury container and the pressures in the mercury. The sensors were attached on several sample mercury targets that were tested at various beam facilities: Oak Ridge Electron Linear Accelerator, Los Alamos Neutron Science Center-Weapons Neutron Research, and Brookhaven National Laboratory's Alternating Gradient Synchrotron. The effects of intense background radiation on measured signals for each sensor are described and discussed. Preliminary results of limited tests at these facilities indicate that the fiber optic sensors function well in this intense radiation environment, whereas conventional electrical sensors are dysfunctional.
Date: October 15, 1998
Creator: Allison, S.W.; Earl, D.D.; Haines, J.R. & Tsai, C.C.
Partner: UNT Libraries Government Documents Department

Proton Decay Studies of the Light Lu, Tm and Ho Isotopes

Description: A double-sided Si-strip detector system has been installed and commissioned at the focal plane of the Recoil Mass Spectrometer at the Holifield Radioactive Ion Beam Facility. The system can be used for heavy charged particle emission studies with half-lives as low as a few {micro}sec. In this paper the authors present identification and study of the decay properties of the five new proton emitters: {sup 140}Ho, {sup 141m}Ho, {sup 145}Tm, {sup 150m}Lu and {sup 151m}Lu.
Date: October 15, 1998
Creator: Akovali, Y.; Batchelder, J.C.; Bingham, C.R.; Davinson, T.; Ginter, T.N.; Gross, C.J. et al.
Partner: UNT Libraries Government Documents Department

The MINOS long-baseline experiment at Fermilab.

Description: The MINOS long-baseline experiment will search for neutrino oscillations by measuring an intense {nu}{sub {mu}} beam at the end of a 730 km flight path. The 10,000 ton MINOS far detector will utilize magnetized steel plates interleaved with track chambers to reconstruct event topologies and to measure the energies of the muons, hadrons and electromagnetic showers produced by neutrino interactions. The experiment is designed to detect {nu}{sub {mu}} {r_arrow} {nu}{sub {tau}} and {nu}{sub {mu}} {r_arrow} {nu}{sub e} oscillations with {Delta}m{sup 2} {ge} 0.001 eV{sup 2} and sin{sup 2}(2{theta}) {ge} 0.01. Any oscillation signal observed can be verified and studied by several independent tests: a near/far rate comparison, the NC/CC event ratio, the CC and NC event energy spectra, and the identification of electrons and {tau} leptons. The neutrino beam can be operated in both wide-band and narrow-band configurations, allowing the detailed study oscillation phenomena. The experiment is scheduled to begin operation in 2001.
Date: October 15, 1997
Creator: Ayres, D. S.
Partner: UNT Libraries Government Documents Department

Use of Dissolved and Colloidal Actinide Parameters within the 1996 Waste Isolation Pilot Plant Compliance Certification Application

Description: Many of the papers in this volume present detailed descriptions of the chemical analyses and methodologies that have been used to evaluate the maximum dissolved and colloid concentrations of actinides within the WIPP repository as part of the performance assessment. This paper describes the program fcm collecting experimental data and provides an overview of how the PA modeled the release of radionuclides to the accessible environment, and how volubility and colloid parameters were used by the PA models.
Date: October 15, 1998
Creator: Moore, R.C. & Stockman, C.T.
Partner: UNT Libraries Government Documents Department