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Combined plate motion and density driven flow in the asthenosphere beneath Saudi Arabia: Evidence from shear-wave splitting and seismic anisotropy

Description: A comprehensive study of mantle anisotropy along the Red Sea and across Saudi Arabia was performed by analyzing shear-wave splitting recorded by stations from three different seismic networks: the largest, most widely distributed array of stations examined across Saudi Arabia to date. Stations near the Gulf of Aqaba display fast orientations that are aligned parallel to the Dead Sea Transform Fault, most likely related to the strike-slip motion between Africa and Arabia. However, most of our observations across Saudi Arabia are statistically the same, showing a consistent pattern of north-south oriented fast directions with delay times averaging about 1.4 s. Fossilized anisotropy related to the Proterozoic assembly of the Arabian Shield may contribute to the pattern but is not sufficient to fully explain the observations. We feel that the uniform anisotropic signature across Saudi Arabia is best explained by a combination of plate and density driven flow in the asthenosphere. By combining the northeast oriented flow associated with absolute plate motion with the northwest oriented flow associated with the channelized Afar plume along the Red Sea, we obtain a north-south oriented resultant that matches our splitting observations and supports models of active rifting processes. This explains why the north-south orientation of the fast polarization direction is so pervasive across the vast Arabian Plate.
Date: February 8, 2006
Creator: Hansen, S & Schwartz, S
Partner: UNT Libraries Government Documents Department

Nucleus-nucleus collisions at very high energies

Description: The present report covers the material of two lectures. The first part, contains a collection of useful formulae from relativistic kinematics and deals with invariant cross sections and multiplicities. The remainder of the paper is on strangeness production in relativistic heavy ion collisions. Some elementary rules for particle production in nucleon-nucleon interactions are presented. This paper also contains arguments on why one expects enhanced strange particle production from the quark-gluon plasma. Next is presented some selected data on strangeness production in Si + Au and other interactions at 14.6 GeV/c per nucleon and from S + S at 200 GeV/c per nucleon. Some conclusions drawn from the experimental results are presented. 10 refs.
Date: January 1, 1990
Creator: Hansen, O.
Partner: UNT Libraries Government Documents Department

Relativistic heavy ion physics

Description: In the fall of 1986, beams of heavy ions up to A = 40 at total energies up to E = 225 GeV/nucleon will become available for experiments at CERN (60 and 225 GeV/nucleon) and at Brookhaven (15.5 GeV/nucleon). Future experiments to look for quark confinement are discussed. 9 refs., 3 figs. (GHT)
Date: January 1, 1985
Creator: Hansen, O.
Partner: UNT Libraries Government Documents Department

Quasielastic reactions

Description: A brief review is presented of the experimental and theoretical situation regarding transfer reactions and inelastic scattering. In the first category there is little (very little) precision data for heavy projectiles and consequently almost no experience with quantitative theoretical analysis. For the inelastic scattering the rather extensive data strongly supports the coupled channels models with collective formfactors. At the most back angles, at intensities about 10/sup -5/ of Rutherford scattering, a second, compound-like mechanism becomes dominant. The description of the interplay of these two opposite mechanisms provides a new challenge for our understanding.
Date: January 1, 1983
Creator: Hansen, O.
Partner: UNT Libraries Government Documents Department

Trends in nuclear spectroscopy with (more or less) direct reactions

Description: Recent experiments on the Gamow-Teller giant resonance are discussed with special regard to the strength sum rules. Some ideas for further investigations of pairing collective modes are presented. The emphasis is on one fermion-two boson states and on two boson transfer reactions. Finally some new experimental results from heavy ion inelastic scattering are presented and the role of such processes in the energy ion mechanisms leading to deep inelastic collisions is discussed.
Date: January 1, 1981
Creator: Hansen, O.
Partner: UNT Libraries Government Documents Department

Strangeness production in Si + Au interactions at 14. 6 GeV/c per nucleon

Description: Production of strange particles in proton-proton interactions is systematically suppressed relative to the production of non-strange particles. A first order goal of experiments on strangeness production in nucleus-nucleus collisions is to find out if strangeness is suppressed in a way similar to the p-p interactions or whether the nuclear environment changes the behaviour. This paper investigates this possibility. 13 refs., 1 tab.
Date: January 1, 1989
Creator: Hansen, O.
Partner: UNT Libraries Government Documents Department

Studies of Nucleon Form Factors with 12 GeV CEBAF and SuperBigBite

Description: The elastic electromagnetic form factors are among the most fundamental quantities that describe the ground-state structure of the proton and neutron. Precision data of the form factors over a wide kinematical range provide a powerful test of current theories of hadron structure. A number of experiments aiming to measure the electric and magnetic elastic form factors of the neutron, G{sub E}{sup n} and G{sub M}{sup n}, and proton, G{sub E}{sup p}, at very high momentum transfer, up to the range of Q{sup 2} = 10-14 (GeV/c){sup 2}, are planned to be carried out with the future 11 GeV electron beam of the upgraded CEBAF at Jefferson Lab. These experiments will determine the nucleon form factors with unprecedented precision to Q{sup 2}-values up to three times higher than those of existing data. We review the approved proposals and the conceptual design of a new spectrometer, SuperBigBite, that will be used in these and other future experiments at Jefferson Lab.
Date: April 1, 2012
Creator: Hansen, Jens-Ole
Partner: UNT Libraries Government Documents Department

ADMINISTRATIVE AND ENGINEERING CONTROLS FOR THE OPERATION OF VENTILATION SYSTEMS FOR UNDERGROUND RADIOACTIVE WASTE STORAGE TANKS

Description: Liquid radioactive wastes from the Savannah River Site are stored in large underground carbon steel tanks. The majority of the waste is confined in double shell tanks, which have a primary shell, where the waste is stored, and a secondary shell, which creates an annular region between the two shells, that provides secondary containment and leak detection capabilities should leakage from the primary shell occur. Each of the DST is equipped with a purge ventilation system for the interior of the primary shell and annulus ventilation system for the secondary containment. Administrative flammability controls require continuous ventilation to remove hydrogen gas and other vapors from the waste tanks while preventing the release of radionuclides to the atmosphere. Should a leak from the primary to the annulus occur, the annulus ventilation would also serve this purpose. The functionality of the annulus ventilation is necessary to preserve the structural integrity of the primary shell and the secondary. An administrative corrosion control program is in place to ensure integrity of the tank. Given the critical functions of the purge and annulus ventilation systems, engineering controls are also necessary to ensure that the systems remain robust. The system consists of components that are constructed of metal (e.g., steel, stainless steel, aluminum, copper, etc.) and/or polymeric (polypropylene, polyethylene, silicone, polyurethane, etc.) materials. The performance of these materials in anticipated service environments (e.g., normal waste storage, waste removal, etc.) was evaluated. The most aggressive vapor space environment occurs during chemical cleaning of the residual heels by utilizing oxalic acid. The presence of NO{sub x} and mercury in the vapors generated from the process could potentially accelerate the degradation of aluminum, carbon steel, and copper. Once identified, the most susceptible materials were either replaced and/or plans for discontinuing operations are executed.
Date: November 13, 2013
Creator: Wiersma, B. & Hansen, A.
Partner: UNT Libraries Government Documents Department

rSUGRA: Putting Nonuniversal Gaugino Masses on the (W)MAP

Description: In this talk, we investigate the relic density and direct detection prospects of rSUGRA, a simple paradigm for supersymmetry breaking that allows for nonuniversal gaugino masses. We present updated plots reflecting the latest cosmological measurements from WMAP.
Date: June 17, 2003
Creator: Birkedal-Hansen, Andreas
Partner: UNT Libraries Government Documents Department

Shielding requirements for the transport of nuclear warhead components under decommissioning

Description: The requirements to carry out accurate shielding calculations involved with the safe off-site transportation of packages containing nuclear warhead components, special assemblies and radioactive materials are discussed. The need for (a) detailed information on the geometry and material composition of the packaging and radioactive load, (b) accurate representation of the differential energy spectra (dN/dE) for the neutron and gamma spectra emitted by the radioactive materials enclosed in the packaging, (c) well-tested neutron and photon cross section libraries, (d) and accurate three-dimensional Monte Carlo transport codes are illustrated. A brief discussion of the need for reliable dose measurements is presented.
Date: September 1, 1994
Creator: Hansen, L.F.
Partner: UNT Libraries Government Documents Department

From science to compliance: Geomechanics studies of the Waste Isolation Pilot Plant

Description: Mechanical and hydrological properties of salt provide excellent bases for geological isolation of hazardous materials. Regulatory certification of the Waste Isolation Pilot Plant (WIPP) testifies to the nearly ideal characteristics of bedded salt deposits in southeast New Mexico. The WIPP history includes decades of testing and scientific investigations, which have resulted in a comprehensive understanding of salt's mechanical deformational and hydrological properties over an applicable range of stresses and temperatures. Comprehensive evaluation of salt's favorable characteristics helped demonstrate regulatory compliance and ensure isolation of radioactive waste placed in a salt geological setting.
Date: June 5, 2000
Creator: HANSEN,FRANCIS D.
Partner: UNT Libraries Government Documents Department

{sup 3}He[pol]({rvec e}, e{prime})X and the neutron electromagnetic form factors

Description: Recent data for the spin-dependent A{sub T}, and A{sub TL}, asymmetries in {sup 3}He[pol]({rvec e}, e{prime}) quasielastic scattering are reviewed. The neutron electric and magnetic form factors are extracted from the data using a plane wave impulse approximation (PWIA) model, and the model uncertainties are estimated. The extracted G{sub M}{sup n} is in agreement with the dipole prediction as well as with other recent experiments. No meaningful result for G{sub E}{sup n} is obtained due to large uncertainties and possible final-state interaction effects. At higher Q{sup 2}, the determination of G{sub E}{sup n} in {sup 3}He[pol]({rvec e},e{prime}) does appear feasible based on the plane wave impulse approximation (PWIA) predictions.
Date: December 31, 1995
Creator: Hansen, J.O.
Partner: UNT Libraries Government Documents Department

Key Geomechanics Issues at the Waste Isolation Pilot Plant Geomechanics

Description: Mechanical and hydrological properties of rock salt provide excellent bases for geological isolation of hazardous materials. Regulatory compliance determinations for the Waste Isolation Pilot Plant (WIPP) stand as testament to the widely held conclusion that salt provides excellent isolation properties. The WIPP saga began in the 1950s when the U.S. National Academy of Sciences (NAS) recommended a salt vault as a promising solution to the national problem of nuclear waste disposal. For over 20 years, the Scientific basis for the NAS recommendation has been fortified by Sandia National Laboratories through a series of large scale field tests and laboratory investigations of salt properties. These scientific investigations helped develop a comprehensive understanding of salt's 4 reformational behavior over an applicable range of stresses and temperatures. Sophisticated constitutive modeling, validated through underground testing, provides the computational ability to model long-term behavior of repository configurations. In concert with advancement of the mechanical models, fluid flow measurements showed not only that the evaporite lithology was essentially impermeable but that the WIPP setting was hydrologically inactive. Favorable mechanical properties ensure isolation of materials placed in a salt geological setting. Key areas of the geomechanics investigations leading to the certification of WIPP are in situ experiments, laboratory tests, and shaft seal design.
Date: September 1, 1999
Creator: Hansen, Francis D.
Partner: UNT Libraries Government Documents Department

GOTHIC MODEL OF BWR SECONDARY CONTAINMENT DRAWDOWN ANALYSES

Description: This article introduces a GOTHIC version 7.1 model of the Secondary Containment Reactor Building Post LOCA drawdown analysis for a BWR. GOTHIC is an EPRI sponsored thermal hydraulic code. This analysis is required by the Utility to demonstrate an ability to restore and maintain the Secondary Containment Reactor Building negative pressure condition. The technical and regulatory issues associated with this modeling are presented. The analysis includes the affect of wind, elevation and thermal impacts on pressure conditions. The model includes a multiple volume representation which includes the spent fuel pool. In addition, heat sources and sinks are modeled as one dimensional heat conductors. The leakage into the building is modeled to include both laminar as well as turbulent behavior as established by actual plant test data. The GOTHIC code provides components to model heat exchangers used to provide fuel pool cooling as well as area cooling via air coolers. The results of the evaluation are used to demonstrate the time that the Reactor Building is at a pressure that exceeds external conditions. This time period is established with the GOTHIC model based on the worst case pressure conditions on the building. For this time period the Utility must assume the primary containment leakage goes directly to the environment. Once the building pressure is restored below outside conditions the release to the environment can be credited as a filtered release.
Date: October 6, 2004
Creator: Hansen, P.N.
Partner: UNT Libraries Government Documents Department

A comparison of the shielding performances of the AT-400A, Model FL and Model AL-R8 containers

Description: A comparison of the neutron and photon dose rates at different locations on the outside surface of the Model AL-RB, Model FL and the AT-400A containers for a given pit load has been done in order to understand the shielding characteristics of these containers. The Model AL-R8 is not certified for transport and is only used for storage of pits, while the Model FL is a certified Type B pit transportation container. The AT-400A is being developed as a type B pit storage and transportation container. The W48, W56 and B83 pits were chosen for this study because of their encompassing features with regard to other pits presently being stored. A detailed description of the geometry and materials of these containers and of the neutron and photon emission spectra from the actinide materials present in the pit have been used in the calculations of the total dose rates. The calculations have been done using the three-dimensional, neutron-photon Monte Carlo code MCNP. The results indicate the need for a containment vessel (CV), as is found in the Model FL and AT-400A containers, in order to assure compliance with 10 CFR 71 regulations. The absence of a CV in the AL-R8 container results in total dose rates well above of the 200mr/hr allowed by the regulations for the W56 pit. Similar behavior will be expected for other pits with configuration similar to the W56 in which the main contribution to the dose rate is from the fission photons.
Date: April 28, 1995
Creator: Hansen, L.F.
Partner: UNT Libraries Government Documents Department

Performance and Modeling of Amorphous Silicon Photovoltaics for Building-Integrated Applications (Preprint prepared for Solar 99)

Description: Amorphous silicon photovoltaic (PV) modules offer several advantages for building-integrated applications. The material can be deposited on glass or flexible substrates, which allows for products like roofing shingles and integrated PV/building glass. The material also has a uniform surface, which is ideal for many architectural applications. Amorphous silicon modules perform well in warm weather and have a small temperature coefficient for power. Depending on the building load, this may be beneficial when compared to crystalline systems. At the National Renewable Energy Laboratory, we are monitoring the performance of a triple-junction a-Si system. The system consists of 72 roofing shingles mounted directly to simulated roofing structures. This paper examines the performance of the building-integrated amorphous silicon PV system and applicability for covering residential loads. A simple model of system performance is also developed and is presented.
Date: June 7, 1998
Creator: Kroposki, B. & Hansen, R.
Partner: UNT Libraries Government Documents Department

SUSY dark matter and non-universal gaugino masses

Description: In this talk the authors investigate the dark matter prospects for supersymmetric models with non-universal gaugino masses. They motivate the use of non-universal gaugino masses from several directions, including problems, with the current favorite scenario, the cMSSM. They then display new corridors of parameter space that allow an acceptable dark matter relic density once gaugino mass universality is relaxed. They finish with a specific string-derived model that allows this universality relaxation and then use the dark matter constraint to make specific statements about the hidden sector of the model.
Date: April 15, 2002
Creator: Birkedal-Hansen, Andreas
Partner: UNT Libraries Government Documents Department

Neutron scattering analysis with microscopic optical model potentials

Description: A review of microscopic optical model potentials used in the analysis of neutron scattering and analyzing power data below 100 MeV (5 {le}E{sub n}{le}100 MeV) is presented. The quality of the fits to the data over a wide massd ({sup 6}Li-{sup 239}Pu) and energy range is discussed. It is shown that reasonably good agreement with the data is obtained with only three parameters, {lambda}{sub V}, {lambda}{sub W}, and {lambda}{sub SO}, which show a smooth mass and energy dependence. These parameters are normalizing constants to the real (V), and imaginary (W) central potentials and the real spin-orbit (V{sub SO}) potential. 14 refs., 7 figs.
Date: September 3, 1991
Creator: Hansen, L.F.
Partner: UNT Libraries Government Documents Department

14 MeV neutron work at the Lawrence Livermore National Laboratory

Description: The 14 MeV neutron work at Lawrence Livermore National Laboratory (LLNL) covers two main areas of interest to this Symposium: (1) measurements and calculations of differential cross sections; and (2) integral measurements of the neutron and gamma emission spectra. In both areas a large number of materials have been studied, spanning a wide mass range (6 < A < 239), of interest to fusion and hybrid reactors. In this presentation a brief description of the experimental techniques and calculational analysis is given for each of the above areas and the measured and calculated cross sections are discussed. 28 refs., 7 figs., 3 tabs.
Date: July 1, 1985
Creator: Hansen, L.F.
Partner: UNT Libraries Government Documents Department

Measurements and calculations of neutron scattering angular distributions over a wide mass and energy range

Description: Neutron elastic and inelastic differential cross sections for targets between /sup 9/Be and /sup 239/Pu at energies, E > 14 MeV have been measured using the Livermore and Ohio University neutron time-of-flight facilities. We review here the data and the analyses based on two local microscopic optical potentials: that of Jeukenne, Lejeune and Mahaux, and that of Brieva and Rook. The results are also compared with calculations using global potentials. Coupled channel formalism has been used in the analysis of targets with strong deformations, such as Be, C, Ta, and actinides. The value of the microscopic optical potentials as a tool to predict elastic and inelastic neutron cross sections over a wide mass and energy range is discussed. The need for neutron measurements up to higher energies and their analysis in conjunction with (p,p) and charge exchange (p,n) data is addressed. 17 refs.
Date: May 1, 1985
Creator: Hansen, L.F.
Partner: UNT Libraries Government Documents Department

Study of proton-induced reactions and correlation with fast-neutron scattering

Description: The generation of cross sections for fast neutron-nucleon interactions obtained from elastic and charge-exchange proton data is discussed in terms of the Lane model formalism. A general description of the interaction of nucleons with nuclei is presented in terms of the optical model and the extended (or coupled-channel) optical model, together with the relation of these models to microscopic calculations of the nucleon-nucleon interaction. Comparisons between neutron elastic data and calculations carried out with optical model potentials obtained from (p,p) and (p,n) data are presented for a large number of nuclei. The validity of the Lane model and the importance of coupled effects in the actinide region are shown in a detailed comparison of calculations for elastic and inelastic neutron differential cross sections and measurements for /sup 232/Th and /sup 238/U.
Date: January 19, 1982
Creator: Hansen, L.F.
Partner: UNT Libraries Government Documents Department

Integral measurements and calculations of neutron and gamma-ray emission at 14 MeV and an overview of the new multi-user tandem at LLNL

Description: In this paper two topics will be presented: (a) the integral measurements and calculations of gamma-ray and neutron emission spectra due to a source of 14 MeV neutrons from materials of interest to thermonuclear reactors and (b) an overview of the new multi-user accelerator facility being built at LLNL. Under (a), recent measurements of the gamma-ray and neutron leakage spectra from materials ranging from Be to /sup 238/U pulsed with 14 MeV neutrons are presented. The Monte Carlo calculational analysis using the codes TART and SANDYL with the ENDL and ENDF/B-V photon-neutron libraries is discussed. Under (b), details of the new multi-disciplinary laboratory centered around a 10 MV Van de Graaff with four ion sources and 19 experimental beam lines will be given. The experimental program to be carried out in this facility will be discussed. 19 refs., 4 figs., 2 tabs.
Date: August 1, 1987
Creator: Hansen, L.F.
Partner: UNT Libraries Government Documents Department

Rossi Alpha Method

Description: The Rossi Alpha Method has proved to be valuable for the determination of prompt neutron lifetimes in fissile assemblies having known reproduction numbers at or near delayed critical. This workshop report emphasizes the pioneering applications of the method by Dr. John D. Orndoff to fast-neutron critical assemblies at Los Alamos. The value of the method appears to disappear for subcritical systems where the Rossi-..alpha.. is no longer an ..alpha..-eigenvalue.
Date: January 1, 1985
Creator: Hansen, G.E.
Partner: UNT Libraries Government Documents Department