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Advanced design and modeling concepts for recombination x-ray lasers

Description: Geometric, kinetic, and trapping issues, in short and ultrashort recombination x-ray lasers, are discussed. The design of a composite target consisting of a lasant strip on a plastic backing is described. Examples of modeling showing the effect of photon trapping and uncertainties in other physical processes on calculated gain coefficients are given. A simple and accurate expression for photon trapping in cylindrical geometry is presented. Recombination lasers that have the ground state as the … more
Date: November 29, 1990
Creator: Eder, D.C.; Rosen, M.D.; Shephard, R.; Staffin, R.; Nash, J.K. & Keane, C.J.
Partner: UNT Libraries Government Documents Department
open access

Computational simulations of plasma flow switches and imploding loads

Description: The Procyon system in the Los Alamos Trailmaster foil implosion project is intended to produce soft x-ray radiation by delivering about 1 MJ of kinetic energy to an imploding plasma liner. The final switching stage of this system will be a Plasma Flow Switch (PFS) which delivers current to the cylindrical foil load. 1-D and 2-D simulations are now being conducted to examine: the initiation of the PFS plasma: the dynamics of the PFS and its switching efficiency; the load implosion and resulting … more
Date: May 29, 1991
Creator: Peterson, D. L.; Bowers, R. L.; Brownell, J. H.; Greene, A. E. & Roderick, N. F.
Partner: UNT Libraries Government Documents Department
open access

Direct, experimental evidence of the Fermi surface in YBa sub 2 Cu sub 3 O sub 7-x

Description: We report new measurements of the electron-positron momentum spectra of YBa{sub 2}Cu{sub 3}O{sub 7-x} performed with ultra-high statistical precision. These data differ from previous results in two significant respects: They show the D{sub 2} symmetry appropriate for untwinned crystals and, more importantly, they show unmistakable, statistically significant, discontinuities that are evidence of a major Fermi surface section. These results provide a partial answer to a question of special signif… more
Date: April 29, 1991
Creator: Haghighi, H.; Kaiser, J. H.; Rayner, S. L.; West, R. N.; Liu, J. Z.; Shelton, R. et al.
Partner: UNT Libraries Government Documents Department
open access

Saturation and kinetic issues for optical-field-ionized plasma x-ray lasers

Description: Lasing between excited states and the ground state following optical-field ionization is studied. Saturation of an x-ray laser when the lower lasing level is a ground state of a H-like or Li-like ion is discussed. Efficiencies of 10{sup {minus}5} to 10{sup {minus}4} are calculated for the 3d{sub 5/2}--2p{sub 3/2} transition at 98 {Angstrom} in Li-like Ne. The assumption that the fine-structure levels are populated according to their statistical weights is shown to be justified through compariso… more
Date: April 29, 1991
Creator: Eder, D.C.; Amendt, P.; Rosen, M.D.; Nash, J.K. & Wilks, S.C.
Partner: UNT Libraries Government Documents Department
open access

Particle distributions in collisionless magnetic reconnection: An implicit Particle-In-Cell (PIC) description

Description: Evidence from magnetospheric and solar flare research supports the belief that collisionless magnetic reconnection can proceed on the Alfven-wave crossing timescale. Reconnection behavior that occurs this rapidly in collisionless plasmas is not well understood because underlying mechanisms depend on the details of the ion and electron distributions in the vicinity of the emerging X-points. We use the direct implicit Particle-In-Cell (PIC) code AVANTI to study the details of these distributions … more
Date: June 29, 1990
Creator: Hewett, D. W.; Francis, G. E. & Max, C. E.
Partner: UNT Libraries Government Documents Department
open access

Thick-target yields of iodine isotopes from proton interactions in Te, and the double-[beta] decay of [sup 128,130]Te

Description: We report thick-target yields of [sup 126,128,130]I from the bombardment of natural Te targets with 15-, 30-, 45- and 50-MeV protons, together with the iodine production cross sections for 1.85- and 5.0-GeV protons. With these data, we have estimated the relative cosmic-ray induced production of [sup 126]Xe, [sup 128]Xe and [sup 13O]Xe in Te ores. These quantities affect the ratio of double-[beta] decay half-lives of [sup 13O]Te and [sup 128]Te. A revised correction of cosmic-ray induced xenon … more
Date: March 29, 1993
Creator: da Cruz, M.T.F.; Chan, Y.D.; Garcia, A.; Larimer, R.M.; Lesko, K.T.; Norman, E.B. et al.
Partner: UNT Libraries Government Documents Department
open access

[beta][sup +] decay and cosmic-ray half-life of [sup 54]Mn

Description: We performed a search for the [beta][sup +] branch of [sup 54]Mn decay. As a cosmic ray, [sup 54]Mn, deprived of its atomic electrons, can decay only via [beta][sup +] and [beta][sup [minus]] decay, with a half-life of the order of 10[sup 6] yr. This turns [sup 54] Mn into a suitable cosmic chronometer for the study of cosmic-ray confinement times. We searched for coincident back-to-back 511-keV [gamma]-rays using two germanium detectors inside a Nal(Tl) annulus. An upper limit of 2[times]10[su… more
Date: March 29, 1993
Creator: da Cruz, M.T.F.; Norman, E.B.; Chan, Y.D.; Garcia, A.; Larimer, R.M.; Lesko, K.T. et al.
Partner: UNT Libraries Government Documents Department
open access

Improved ground-penetrating radar, bridge decks

Description: Inspection of high-value structures, like bridges and buildings, using Ground Penetrating Radar (GPR) is an application of a technology that is growing in importance. In a typical inspection application, inspectors use GPR to locate structural components, like embedded reinforcing bars, to avoid weakening the structure while collecting core samples for detailed inspection. Advanced GPR, integrated with imaging technologies for use as an NDE tool, can provide the capability to quickly locate and… more
Date: November 29, 1993
Creator: Warhus, J. P.; Mast, J. E.; Johansson, E. M. & Nelson, S. D.
Partner: UNT Libraries Government Documents Department
open access

ResonantSonic drilling: History, progress and advances in environmental restoration programs

Description: ResonantSonic{sup SM} drilling is being used in the environmental industry to drill faster, cheaper, and safer than conventional drilling methodologies. ResonantSonic is a registered service mark of the Water Development Corporation, Woodland, California. The ResonantSonic drilling method, requires no mud, air or water for rapid penetration through geologic materials ranging from rock and clay to sand and boulders. The specialized drill head imparts high frequency vibrations into a steel drill … more
Date: September 29, 1993
Creator: Volk, B. W.; McLellan, G. W.; Moak, D. J.; Lerch, R. E.; Thompson, K. M. & Barrow, J. C.
Partner: UNT Libraries Government Documents Department
open access

Elastic spin observables and proton wave function normalization at large t

Description: We summarize the role of spin observables in testing the foundations of exclusive QCD at large t. Polarized elastic scattering experiments can shed light on fundamental properties of protons, such as helicity conservation, normalization of the wave function and structure. Specific QCD motivated predictions for the spin observables are presented, which can be tested at polarized proton beam facilities. In this paper, two kinematic regions are considered: 90{degrees} c.m. at large {vert_bar} t {v… more
Date: November 29, 1993
Creator: Ramsey, G. P.
Partner: UNT Libraries Government Documents Department
open access

Polyurethane foam cable bundle block

Description: Blocking the flow of radioactive gas in the emplacement hole requires attention to three items: stemming materials, cables, and spaces between the cables. This paper deals with an improvement in the latter; that is, filling the spaces between the cables and, thus, forming a bundle block. We have tested a two-part polyurethane foam in the field with apparent success. Field tests included recovery of sample cable bundles from a nuclear test in a tunnel. The foam creates a bundle block that surviv… more
Date: October 29, 1993
Creator: Mercier, J. A.; Cornell, R. H.; Pratuch, S. M. & Lundberg, A.
Partner: UNT Libraries Government Documents Department
open access

{beta}{sup +} decay and cosmic-ray half-life of {sup 54}Mn

Description: We performed a search for the {beta}{sup +} branch of {sup 54}Mn decay. As a cosmic ray, {sup 54}Mn, deprived of its atomic electrons, can decay only via {beta}{sup +} and {beta}{sup {minus}} decay, with a half-life of the order of 10{sup 6} yr. This turns {sup 54} Mn into a suitable cosmic chronometer for the study of cosmic-ray confinement times. We searched for coincident back-to-back 511-keV {gamma}-rays using two germanium detectors inside a Nal(Tl) annulus. An upper limit of 2{times}10{su… more
Date: March 29, 1993
Creator: da Cruz, M. T. F.; Norman, E. B.; Chan, Y. D.; Garcia, A.; Larimer, R. M.; Lesko, K. T. et al.
Partner: UNT Libraries Government Documents Department
open access

Semiquantum Chaos and the Large N Expansion

Description: When a classical oscillator is interacting with a purely quantum mechanical oscillator, described by the Lagrangian L = 1/2 x{sup 2} + 1/2A{sup 2} - 1/2 (m{sup 2} + e{sup 2} A{sup 2})x{sup 2}, where A is a classical variable and x is a quantum operator the relevant degrees of freedom for the quantum oscillator when {l_angle}x(t)x(t){r_angle} = G(t). The classical Hamiltonian dynamics governing the variables A(t). {Pi}{sub A}(t). G(t) and {Pi}{sub G}(t) is chaotic so that the results of making m… more
Date: June 29, 1994
Creator: Cooper, F.; Habib, S.; Kluger, Y.; Dawson, J.; Meredith, D. & Shepard, H.
Partner: UNT Libraries Government Documents Department
open access

A parallel hashed oct-tree N-body algorithm

Description: We report on an efficient adaptive N-body method which we have recently designed and implemented. The algorithm computers the forces on an arbitrary distribution of bodies in a time which scales as N log N with particle number. The accuracy of the force calculations is analytically bounded, and can be adjusted via a user defined parameter between a few percent relative accuracy, down to machine arithmetic accuracy. Instead of using pointers to indicate the topology of the tree, we identify each… more
Date: March 29, 1993
Creator: Warren, M. S. & Salmon, J. K.
Partner: UNT Libraries Government Documents Department
open access

Energetic materials destruction using molten salt

Description: The Lawrence Livermore National Laboratory in conjunction with the Energetic Materials Center is developing methods for the safe and environmentally sound destruction of explosives and propellants as a part of the Laboratory`s ancillary demilitarization mission. LLNL has built a small-scale unit to test the destruction of HE using the Molten Salt Destruction (MSD) Process. In addition to the high explosive HMX, destruction has been carried out on RDX, PETN, ammonium picrate, TNT, nitroguanadine… more
Date: April 29, 1994
Creator: Upadhye, R. S.; Watkins, B. E.; Pruneda, C. O. & Brummond, W. A.
Partner: UNT Libraries Government Documents Department
open access

Meshes: The next generation

Description: Building complex meshes for large-scale numerical simulations presents immense difficulties in exploiting high-performance computers. Industry and research leaders will describe the current state of the art for generating meshes for such large scientific problems. This will be followed by a panel and general audience discussion of the algorithmic and architectural issues surrounding the generation of meshes with10{sup 7} to 10{sup 9} grid points. (Note: The terms ``mesh`` and ``grid`` are used … more
Date: August 29, 1994
Creator: Christon, M.; Hardin, D.; Compton, J. & Zosel, M.
Partner: UNT Libraries Government Documents Department
open access

High-precision reflectometry of multilayer coatings for extreme ultraviolet lithography

Description: Synchrotron-based reflectometry is an important technique for the precise determination of optical properties of reflective multilayer coatings for Extreme Ultraviolet Lithography (EUVL). Multilayer coatings enable normal incidence reflectances of more than 65% in the wavelength range between 11 and 15 nm. In order to achieve high resolution and throughput of EUVL systems, stringent requirements not only apply to their mechanical and optical layout, but also apply to the optical properties of t… more
Date: December 29, 1999
Creator: Wedowski, M; Underwood, J H; Gullikson, E M; Bajt, S; Folta, J A; Kearney, P A et al.
Partner: UNT Libraries Government Documents Department
open access

Silicon microelectronic field-emissive devices for advanced display technology

Description: Field-emission displays (FEDS) offer potential advantages of high luminous efficiency, low power consumption, and low cost compared to AMLCD or CRT technologies. An LLNL team has developed silicon-point field emitters for vacuum triode structures and has also used thin-film processing techniques to demonstrate planar edge-emitter configurations. LLNL is interested in contributing its experience in this and other FED-related technologies to collaborations for commercial FED development. At LLNL,… more
Date: March 29, 1993
Creator: Morse, J. D.
Partner: UNT Libraries Government Documents Department
open access

Atmospheric transport analysis used in hazard screening methodology

Description: Simple, but conservative, atmospheric transport models are used in the initial stages of a hazard screening methodology to determine a preliminary hazard rank. The hazard rank is one indicator of the additional effort, if any, that must be applied to determine if a system is safe. Simple methods avoid prolonged calculations at this early stage when details of potential accidents may be poorly defined. The models are used to simulate the consequences resulting from accidental releases of toxic s… more
Date: June 29, 1992
Creator: Bloom, S. G.
Partner: UNT Libraries Government Documents Department
open access

Gold Beam Losses at the AGS Booster Injection.

Description: Gold beam injection efficiency decreases in proportional to the beam loss in the AGS Booster. A close look shows that large number of electrons, ions, and neutral particles are created when the gold beam scrapes wall. To investigate the neutral particle production due to the beam loss, local vacuum measurement was made during the 1998 run. It shows that the pressure created by the Booster Au{sup 31+} beam loss at injection has a 35 ms decay time constant. The beam loss created pressure bump in … more
Date: March 29, 1999
Creator: Zhang, S. Y. & Ahrens, L. A.
Partner: UNT Libraries Government Documents Department
open access

A Cupronickel Rotating Band Pion Production Target for Muon Colliders.

Description: A conceptual design is presented for a high power cupronickel pion production target. It forms a circular band in a horizontal plane with approximate dimensions of: 2.5 meters radius, 6 cm high and 0.6 cm thick. The target is continuously rotated at 3 m/s to carry heat away from the production region to a water cooling channel. Bunches of 16 GeV protons with total energies of 270 kl and repetition rates of 15 Hz are incident tangentially to arc of the target along the symmetry axis of a 20 Tesl… more
Date: March 29, 1999
Creator: King, B. J.; Weggel, R. J.; Mokhov, N. V. & Moser, S. S.
Partner: UNT Libraries Government Documents Department
open access

Precision Magnetic Elements for the SNS Storage Ring.

Description: Magnetic elements for an accumulator storage ring for a 1 GeV Spallation Neutron Source (SNS) have been under design. The accumulation of very high intensity protons in a storage ring requires beam optical elements of very high purity to minimize higher order resonances in the presence of space charge. The parameters of the elements required by the accumulator lattice design have been reported. The dipoles have a 17cm gap and are 124cm long. The quadrupoles have a physical length to aperture di… more
Date: March 29, 1999
Creator: Danby, G.; Jackson, J. & Spataro, C.
Partner: UNT Libraries Government Documents Department
open access

A P-Carbon CNI Polarimeter for RHIC.

Description: The RHIC spin program requires excellent polarimetry so that the knowledge of the beam polarization does not limit the errors on the experimental measurements. However, polarimetry of proton beams with energies higher than about 30GeV poses a difficult challenge. For polarization monitoring during operation, a fast and reliable polarimeter is required that produces a polarization measurement with a 10% relative error within a few minutes. The p-Carbon elastic scattering in the Coulomb-Nuclear-S… more
Date: March 29, 1999
Creator: Huang, H.; Bai, M.; Bunce, G.; Makdisi, Y.; Roser, T.; Imai, K. et al.
Partner: UNT Libraries Government Documents Department
open access

Design of a Resonant Extraction System for the AGS Booster.

Description: The Booster Application Facility (BAF) will employ heavy ion beams of many different ion species and at beam energies ranging from 0.04 to 3.07 GeV/nucleon. Resonant extraction is required in order to deliver a continuous stream of particles. In this report we describe the beam requirements and the system design. The basic design is a third integer resonant extraction process which employs a single thin magnetic septum and a thick septum ejector magnet The expected extraction efficiency is abou… more
Date: March 29, 1999
Creator: Brown, K.; Cullen, J.; Glenn, J. W.; Lee, Y. Y.; Mcnerney, A.; Niederer, J. et al.
Partner: UNT Libraries Government Documents Department
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