The Gamma-ray Galactic Diffuse Radiation and CerenkovTelescopes (open access)

The Gamma-ray Galactic Diffuse Radiation and CerenkovTelescopes

None
Date: July 15, 1995
Creator: Chardonnet, P.; Salati, P.; Slik, J.; Grenier, I. & Smoot, George F.
System: The UNT Digital Library
Analytic electrostatic solution of an axisymmetric accelerator gap (open access)

Analytic electrostatic solution of an axisymmetric accelerator gap

Numerous computer codes calculate beam dynamics of particles traversing an accelerating gap. In order to carry out these calculations the electric field of a gap must be determined. The electric field is obtained from derivatives of the scalar potential which solves Laplace`s equation and satisfies the appropriate boundary conditions. An integral approach for the solution of Laplace`s equation is used in this work since the objective is to determine the potential and fields without solving on a traditional spatial grid. The motivation is to quickly obtain forces for particle transport, and eliminate the need to keep track of a large number of grid point fields. The problem then becomes one of how to evaluate the appropriate integral. In this work the integral solution has been converted to a finite sum of easily computed functions. Representing the integral solution in this manner provides a readily calculable formulation and avoids a number of difficulties inherent in dealing with an integral that can be weakly convergent in some regimes, and is, in general, highly oscillatory.
Date: March 15, 1995
Creator: Boyd, J. K.
System: The UNT Digital Library
The Speciation of Groundwater Contaminated with Coal Pile Leachate at the Savannah River Site, South Carolina (open access)

The Speciation of Groundwater Contaminated with Coal Pile Leachate at the Savannah River Site, South Carolina

Modeling the transport of contaminant metals and designing systems for their remediation requires an understanding of the metal`s speciation. Thus, analysis of contaminant speciation and evaluation of the processes that can change the speciation should be done during characterization of the contaminated site. This approach is being used at the Savannah River Site for a metals contaminated site that will serve as a test platform for metals remediation technologies. The site is adjacent to a coal storage pile and the basin that contains the coal pile runoff. A network of well clusters allows definition of the plume, including profiles of contamination with depth. The groundwater is acidic (pH {approx} 2) and contains high concentrations of sulfate (up to 2300 mg/l) and metals, with chromium, nickel, cadmium and lead exceeding drinking water standards. Aluminum and total iron concentrations range up to 1326 mg/l and 7991 mg/l, respectively. Speciation calculations on dissolved contaminants indicate that as much as 65% of the lead, 54% of the cadmium, and 34% of the nickel may be present in sulfate complexes. Chromium occurs predominantly as Cr{sup +3}. There is evidence that some contaminant metals may be associated with colloidal material. Contamination in the groundwater is stratified …
Date: May 15, 1995
Creator: Denham, M. E. & Nichols, R. L.
System: The UNT Digital Library
Non-universal SUSY breaking, hierarchy and squark degeneracty (open access)

Non-universal SUSY breaking, hierarchy and squark degeneracty

I discuss non-trivial effects in the soft SUSY breaking terms which appear when one integrates out heavy fields. The effects exist only when the SUSY breaking terms are non-universal. They may spoil (1) the hierarchy between the weak and high-energy scales, or (2) degeneracy among the squark masses even in the presense of a horizontal symmetry. I argue, in the end, that such new effects may be useful in probing physics at high-energy scales from TeV-scale experiments.
Date: March 15, 1995
Creator: Murayama, Hitoshi
System: The UNT Digital Library
FT-ICR mass spectrometry of very highly charged atomic ions (open access)

FT-ICR mass spectrometry of very highly charged atomic ions

The authors report FT-ICR measurements of samples trapped in the electron beam ion trap (EBIT) at Livermore. They made use of the access provided by the radial x-ray slots. They constructed two probes that could be inserted into the 2-mm wide slots. The probes each subtend only 25{degree} and face each other 180{degree} apart. They show a typical transformed spectrum of highly charged {sup 84}Kr ions obtained with this system. The spectrum was obtained by exciting with a 300-{mu}s sweep from 17.5 to 19.5 MHz. The resonance peaks of {sup 84}Kr{sup 34+}, {sup 84}Kr{sup 35+}, and {sup 84}Kr{sup 36+} are clearly visible.
Date: May 15, 1995
Creator: Schweikhard, L.; Beck, B. & Beiersdorfer, P.
System: The UNT Digital Library
Safe new reactor for radionuclide production (open access)

Safe new reactor for radionuclide production

In late 1995, DOE is schedule to announce a new tritium production unit. Near the end of the last NPR (New Production Reactors) program, work was directed towards eliminating risks in current designs and reducing effects of accidents. In the Heavy Water Reactor Program at Savannah River, the coolant was changed from heavy to light water. An alternative, passively safe concept uses a heavy-water-filled, zircaloy reactor calandria near the bottom of a swimming pool; the calandria is supported on a light-water-coolant inlet plenum and has upflow through assemblies in the calandria tubes. The reactor concept eliminates or reduces significantly most design basis and severe accidents that plague other deigns. The proven, current SRS tritium cycle remains intact; production within the US of medical isotopes such as Mo-99 would also be possible.
Date: February 15, 1995
Creator: Gray, P.L.
System: The UNT Digital Library
Physics with the collider detectors at RHIC and the LHC (open access)

Physics with the collider detectors at RHIC and the LHC

On January 8, 1995, over 180 participants gathered to hear the QM95 preconference workshop on `Physics with the Collider Detectors at RHIC and the LHC`. The goal was to bring together the experimentalists from a wide community of hadron and heavy ion collider detector collaborations. The speakers were encouraged to present the current status of their detectors, with all the blemishes, and the audience was encouraged to share their successes and failures in approaching similar detector design issues. The presentations were excellent and the discussions were lively and stimulating. The editors hope that the reader will find these proceedings to be equally stimulating. Separate abstracts have been submitted to the energy database from articles in this report.
Date: July 15, 1995
Creator: Thomas, J. & Hallman, T.
System: The UNT Digital Library
Recent results from the super EBIT (open access)

Recent results from the super EBIT

The Super EBIT device at LLNL can produce and trap any highly charged ion at rest in the laboratory, including bare U{sup 92+} ions. Recently, the ionization cross sections for high-Z hydrogenlike ions have been measured for the first time, and measurements of the L-shell ionization cross sections for uranium ions are in progress. The two-electron contributions to the ground state energies of heliumlike ions have been directly measured using a novel technique, and spectra of 2s-2p transitions in highly ionized thorium and uranium have been used to test QED corrections to the energy levels of few electron high-Z ions. A new capability for the study of rare isotopes has been demonstrated. Ion cooling has been used to reduce the thermal broadening of x-ray emission lines to the point where natural line widths can be observed in some cases.
Date: September 15, 1995
Creator: Marrs, R.E.
System: The UNT Digital Library
A limit on {sigma} {center_dot} BR (B{sub c}{sup {+-}} {yields} J/{psi} + {pi}{sup {+-}})/{sigma} {center_dot} BR(B{sub u}{sup {+-}} {yields} J/{psi} + K{sup {+-}}) in {radical}s = 1.8 TeV proton-antiproton collisions (open access)

A limit on {sigma} {center_dot} BR (B{sub c}{sup {+-}} {yields} J/{psi} + {pi}{sup {+-}})/{sigma} {center_dot} BR(B{sub u}{sup {+-}} {yields} J/{psi} + K{sup {+-}}) in {radical}s = 1.8 TeV proton-antiproton collisions

We report on the results of a search for the B{sub c} (b{bar c}) meson in the decay B{sub c}{sup +-} {yields} J/{psi} + {pi}{sup +-}. This search is guided by a control sample of decays of B{sub u} mesons to J/{psi} + K and uses {approx_equal} 75pb{sup -1} of data collected at the Collider Detector Facility (CDF) at Fermilab. The lifetime of the B{sub c} meson is unknown, so the 95% confidence level limit on {sigma} {center_dot} BR(B{sub c} {yields} {psi} + {pi})/{sigma} {center_dot} BR(B{sub u} {yields} {psi} + K) is obtained as a function of the B{sub c} lifetime.
Date: July 15, 1995
Creator: Abe, F.
System: The UNT Digital Library
Xtoys: Cellular automata on xwindows (open access)

Xtoys: Cellular automata on xwindows

Xtoys is a collection of xwindow programs for demonstrating simulations of various statistical models. Included are xising, for the two dimensional Ising model, xpotts, for the q-state Potts model, xautomalab, for a fairly general class of totalistic cellular automata, xsand, for the Bak-Tang-Wiesenfield model of self organized criticality, and xfires, a simple forest fire simulation. The programs should compile on any machine supporting xwindows.
Date: August 15, 1995
Creator: Creutz, M.
System: The UNT Digital Library
Laser Properties of an Improved Average-Power Nd-Doped Phosphate Glass (open access)

Laser Properties of an Improved Average-Power Nd-Doped Phosphate Glass

The Nd-doped phosphate laser glass described herein can withstand 2.3 times greater thermal loading without fracture, compared to APG-1 (commercially-available average-power glass from Schott Glass Technologies). The enhanced thermal loading capability is established on the basis of the intrinsic thermomechanical properties (expansion, conduction, fracture toughness, and Young`s modulus), and by direct thermally-induced fracture experiments using Ar-ion laser heating of the samples. This Nd-doped phosphate glass (referred to as APG-t) is found to be characterized by a 29% lower gain cross section and a 25% longer low-concentration emission lifetime.
Date: March 15, 1995
Creator: Payne, S. A.; Marshall, C. D. & Bayramian, A. J.
System: The UNT Digital Library
Copper electroplating process for sub-half-micron ULSI structures (open access)

Copper electroplating process for sub-half-micron ULSI structures

We have utilized electroplating technology in a damascene process to produce low resistance copper interconnects in sub-half-micron ULSI patterns having aspect ratios of 2.4:1. The use of a pulsed-voltage plating technique allows trench filling capability without voids. Samples of 150 mm diameter were patterned and sputtered with a barrier layer, followed by a copper seed layer. Pulsed-voltage electroplating, deposited about 2 microns of copper uniformly (1 sigma < 5%) over the surface. The electroplated copper has low levels of impurities, excellent adhesion, excellent step coverage, and rates comparable to other deposition methods. We present details of the electroplating equipment, and data on the filling characteristics of the copper metallization which prevent void formation and reduce contact resistance.
Date: May 15, 1995
Creator: Contolini, Robert J.; Tarte, Lisa; Graff, Robert T.; Evans, Leland B.; Cox, J. Neal; Puich, Marc et al.
System: The UNT Digital Library
Combline antenna modeling for plasma heating (open access)

Combline antenna modeling for plasma heating

The combline antenna for plasma heating, as proposed by General Atomics, has unique potential for solving many plasma drive problems. The benefit of the combline design is the utilization of the coupling between elements that avoids a more cumbersome multidrive system. This design is being investigated using computational EM modeling codes in the 100-400 MHz band using resources at General Atomics and LLNL. Preliminary experimental results, using a combline mockup, agree well with 3D modeling efforts including resonant frequency alignment and amplitudes. These efforts have been expanded into an endeavor to optimize the combline design using both time and frequency domain codes. This analysis will include plasma coupling but to date has been limited to antenna effects. The combline antenna system is modeled in 3D using a combination of computational tools in the time domain, for temporal feature isolation purposes, and in the frequency domain, for resonant structure analysis. Both time and frequency domain modeling details include the Faraday shield elements, the strap elements, and the feed structure.
Date: May 15, 1995
Creator: Nelson, S. D.; Kamin, G. & Van Maren, R.
System: The UNT Digital Library
No-thermal plasma processing of VOCs and NO{sub x} at LLNL (open access)

No-thermal plasma processing of VOCs and NO{sub x} at LLNL

For the past few years, Lawrence Livermore National Laboratory has been conducting a comprehensive research program on the application of non-thermal plasmas for air pollution control and abatement. This program combines an extensive modeling effort with an experimental facility and test program. We believe that there are two major issues to be addressed in order to apply non-thermal plasma processing to air pollution control; these are electrical energy consumption and byproduct identification. The thrust of our work has been to understand the scalability of the non-thermal process by focusing on the energy efficiency of the non-thermal process and to identify the byproducts to ensure that effluent gases from a non-thermal processor are benign. We have compared different types of electrical discharge reactors both theoretically and experimentally. Our interests in the application of non-thermal plasmas vary from the destruction of volatile organic compounds (VOCs) to NO{sub x} reduction for mobile applications. This paper will discuss the processing of both NO{sub x} and VOCs by non-thermal plasmas at LLNL.
Date: February 15, 1995
Creator: Merritt, B. T.; Hsiao, M. C.; Penetrante, B. M.; Vogtlin, G. E. & Wallman, P. H.
System: The UNT Digital Library
Applying simulation and logistics modeling to tansportation issues (open access)

Applying simulation and logistics modeling to tansportation issues

This paper describes an application where transportation logistics and simulation tools are integrated to create a modeling environment for transportation planning. The Transportation Planning Model (TPM) is a tool developed for the Department of Energy (DOE) to aid in the long-term planning of their transportation resources. The focus of the tool is to aid DOE and Sandia National Laboratory analysts in the planning of future fleet sizes, driver and support personnel sizes, base site locations, and resource balancing among the base sites. The design approach is to develop a rapid modeling environment which integrates graphical user interfaces, logistics optimizing tools, and simulation modeling. Using the TPM an analyst can easily set up a shipment scenario and perform multiple ``What If`` evaluations. The TPM has been developed on personal computers using commercial off-the-shelf software tools under the WINDOW{reg_sign} operating environment.
Date: August 15, 1995
Creator: Funkhouser, B. R.; Ballweg, E. L. & Mackoy, R. D.
System: The UNT Digital Library
On the road to the solution of the Solar Neutrino Problem (open access)

On the road to the solution of the Solar Neutrino Problem

The present status of solar neutrino experiments is reviewed. The discrepancy between the experimental results and the theoretical expectations has come to be known as the Solar Neutrino Problem. Possible solutions to this problem are discussed. The next generation of solar neutrino experiments are described.
Date: August 15, 1995
Creator: Norman, E.B.
System: The UNT Digital Library
Smoothing by spectral dispersion using random phase modulation for inertial confinement fusion (open access)

Smoothing by spectral dispersion using random phase modulation for inertial confinement fusion

Numerical simulations of beam smoothing using random phase modulation and grating dispersion are presented. Spatial spectra of the target illumination show that significantly improved smoothing at low spatial frequency is achieved while maintaining uniform intensity in the laser amplifier.
Date: November 15, 1995
Creator: Rothenberg, J.E.
System: The UNT Digital Library
System study of a diode-pumped solid-state-laser driver for inertial fusion energy (open access)

System study of a diode-pumped solid-state-laser driver for inertial fusion energy

The present a conceptual design of a diode-pumped solid-state-laser (DPSSL) driver for an inertial fusion energy (IFE) power plant based on the maximized cost of electricity (COE) as determined in a comprehensive systems study. This study contained extensive detail for all significant DPSSL physics and costs, plus published scaling relationships for the costs of the target chamber and the balance of plant (BOP). Our DPSSL design offers low development cost because it is modular, can be fully tested functionally at reduced scale, and is based on mature solid-state-laser technology. Most of the parameter values that we used are being verified by experiments now in progress. Future experiments will address the few issues that remain. As a consequence, the economic and technical risk of our DPSSL driver concept is becoming rather low. Baseline performance at 1 GW{sub e} using a new gain medium [Yb{sup 3+}-doped Sr{sub 5}(PO{sub 4}){sub 3}F or Yb:S-FAP] includes a product of laser efficiency and target gain of {eta}G = 7, and a COE of 8.6 cents/kW{center_dot}h, although values of {eta}G {ge} 11 and COEs {le}6.6 cents/kW{center_dot}h are possible at double the assumed target gain of 76 at 3.7 MJ. We present a summary of our results, discuss …
Date: June 15, 1995
Creator: Orth, C.D. & Payne, S.A.
System: The UNT Digital Library
Magnetic correlations in doped transition metal oxides (open access)

Magnetic correlations in doped transition metal oxides

The authors review recent reactor- and spallation-source-based neutron scattering experiments on the magnetic fluctuations and order in a variety of doped transition metal oxides. In particular, data are shown for the NiO chain compound, Y{sub 2{minus}x}Ca{sub x}BaNiO{sub 5}, the two-dimensional cuprate superconductors La{sub 2{minus}x}Sr{sub x}CuO{sub 4} and YBa{sub 2}Cu{sub 3} O{sub 6+x}, and the classical three-dimensional ``Mott-Hubbard`` system V{sub 2{minus}y}O{sub 3}.
Date: February 15, 1995
Creator: Aeppli, G.; Bao, W. & Broholm, C.
System: The UNT Digital Library
Ball lens reflections by direct solution of Maxwell`s equations (open access)

Ball lens reflections by direct solution of Maxwell`s equations

Ball lenses are important for many applications. For example, ball lenses can be used to match the mode of a laser diode (LD) to a single mode fiber (SMF), essential for low-loss, high bit rate communication systems. Modeling the propagation of LD light through a ball lens presents a challenge due to the large angular divergence of the LD field (typically > 20{degrees} HWHM) and the subsequent significant effect of spherical aberration. Accurately calculating the reflected power is also difficult, but essential, since reflections as small as {minus}30 dB can destabilize the LID. A full-wave analysis of this system using, e.g., a finite-difference time-domain method is not practical because of the size of the ball lens, typically hundreds of wavelengths in diameter. Approximate scalar methods can give good results in some cases, but fail to calculate reflected power and miss polarization effects entirely. The authors` approach exploits the fact that the scattering of an arbitrary electromagnetic beam from a sphere is an exactly solvable problem. The scattering of a plane wave from a sphere is a classical problem which was solved by Mie in 1908. More recently, various workers have considered the scattering of a Gaussian beam from a sphere …
Date: February 15, 1995
Creator: Ratowsky, R. P.; Deri, R. J.; Kallman, J. S. & Trott, G.
System: The UNT Digital Library
New solid state lasers from the ultraviolet to the mid-infrared (open access)

New solid state lasers from the ultraviolet to the mid-infrared

The authors discuss three new laser materials that offer improved access to the ultraviolet, near infrared and mid-infrared spectral regions. In order for each of these materials to have been identified, a particular hurdle needed to be overcome with respect to the fundamental laser physics impacting the material. In the case of the 280-320nm Ce:LiSAF laser, the main issue is the need to reduce the loss associated with excited state absorption, while for 1047nm Yb:S-FAP it is the ground state absorption at the laser wavelength that must be minimized. Cr:ZnSe has been down-selected from a number of potential candidates which could lase in the 2200-3000nm region, in order to mitigate the detrimental impact of nonradiative decay. In all three cases the authors discuss how appropriate consideration of fundamental concerns has led to the identification and understanding of the new laser system.
Date: August 15, 1995
Creator: Payne, S. A.; Krupke, W. F. & Beach, R. J.
System: The UNT Digital Library
CRYSTALLINE CERAMICS:  WASTE FORMS FOR THE DISPOSAL OF WEAPONS PLUTONIUM (open access)

CRYSTALLINE CERAMICS: WASTE FORMS FOR THE DISPOSAL OF WEAPONS PLUTONIUM

At present, there are three seriously considered options for the disposition of excess weapons plutonium: (i) incorporation, partial burn-up and direct disposal of MOX-fuel; (ii) vitrification with defense waste and disposal as glass ``logs``; (iii) deep borehole disposal (National Academy of Sciences Report, 1994). The first two options provide a safeguard due to the high activity of fission products in the irradiated fuel and the defense waste. The latter option has only been examined in a preliminary manner, and the exact form of the plutonium has not been identified. In this paper, we review the potential for the immobilization of plutonium in highly durable crystalline ceramics apatite, pyrochlore, monazite and zircon. Based on available data, we propose zircon as the preferred crystalline ceramic for the permanent disposition of excess weapons plutonium.
Date: May 15, 1995
Creator: Ewing, R. C.; Lutze, W. & Weber, W. J.
System: The UNT Digital Library
Measurement of the Bespalov-Talanov gain spectrum in a dispersive medium with large n{sub 2} (open access)

Measurement of the Bespalov-Talanov gain spectrum in a dispersive medium with large n{sub 2}

Conditions which seed the self focussing of high-power broadband laser beams are determined by examining growth rates for plane-wave perturbations on a strong pump field as a function of frequency and angle. Measurements verifying predictions of growth based on the linearized stability analysis of Bespalov and Talanov extended to broadband fields are reported.
Date: June 15, 1995
Creator: Wegner, P. J.; Feit, M. D.; Fleck, J. A., Jr. & Eimerl, D.
System: The UNT Digital Library