Structural and magnetic properties of UCo{sub 1/3}T{sub 2/3}Al solid solutions (T = Ru, Pt, Rh). (open access)

Structural and magnetic properties of UCo{sub 1/3}T{sub 2/3}Al solid solutions (T = Ru, Pt, Rh).

We report on neutron diffraction studies of UCo{sub 1/3}T{sub 2/3}Al (T = Ru, Pt, Rh). All three solid solutions form in the hexagonal ZrNiAl structure. The Ru-containing compound is found to be chemically ordered, while the Pt-containing compound is nearly disordered and the Rh-containing compound is purely disordered. All three compounds exhibit long-range magnetic order with rather small U moments.
Date: August 6, 1999
Creator: Andreev, A. V.; Bordallo, H. N.; Chang, S.; Nakotte, H.; Schultz, A. J.; Sechovsky, V. et al.
System: The UNT Digital Library
Testing of vacuum pumps for APT/LEDA RFQ (open access)

Testing of vacuum pumps for APT/LEDA RFQ

Two vacuum systems were designed and built for the RFQ (Radio Frequency Quadrupole) cavity in the APT/LEDA (Low Energy Demonstration Accelerator) linac. The gas load from the proton beam required very high hydrogen pump speed and capacity. The gas load from the high power RF windows also required very high hydrogen pump speed for the RF window vacuum system. Cryopumps were chosen for the RFQ vacuum system and ST185 sintered non- evaporable getter (NEG) cartridges were chosen for the RF window vacuum system. Hydrogen pump speed and capacity measurements were carried out for a commercial cryopump and a NEG pump. This paper will discuss the test procedures and the results of the measurements.
Date: August 6, 1998
Creator: Behne, D.; Shen, S.; Valdiviez, R.; Wilson, N. G. & Schrage, D.
System: The UNT Digital Library
Startup of Savannah River`s Defense Waste Processing Facility to produce radioactive glass (open access)

Startup of Savannah River`s Defense Waste Processing Facility to produce radioactive glass

The Savannah River Site (SRS) began production of radioactive glass in the Defense Waste Process Facility (DWPF) in 1996 following an extensive test program discussed earlier. Currently DWPF is operating in a `sludge only` mode to produce radioactive glass consisting of washed high-level waste sludge and glass frit. Future operations will produce radioactive glass consisting of washed high-level waste sludge, precipitated cesium, and glass frit. This paper provides an update of processing activities to date, operational problems encountered since entering radioactive operations, and the programs underway to solve them.
Date: August 6, 1997
Creator: Bennett, W. M. & Elder, H. H.
System: The UNT Digital Library
The national wildfire prediction program: a key piece of the wildfire solution (open access)

The national wildfire prediction program: a key piece of the wildfire solution

Lawrence Livermore National Laboratory and Los Alamos National Laboratory have developed an initiative for a National Wildfire Prediction Program. The program provides guidance for fire managers throughout the country, assisting them to efficiently use limited fire-fighting resources. To achieve maximum cost leveraging, the program builds upon existing physics-based atmospheric and wildfire modeling efforts, a proven emergency response infrastructure, state-of-the-art computer science, and the world's most advanced supercomputers to create a comprehensive wildfire prediction system.
Date: August 6, 1999
Creator: Bossert, J E; Bradley, M M; Hanson, H P; Schomer, C L & Sumikawa, D A
System: The UNT Digital Library
Low-Level Radioactive Waste Management at the Nevada Test Site - Year 2000 Current Status (open access)

Low-Level Radioactive Waste Management at the Nevada Test Site - Year 2000 Current Status

The performance objectives of the Department of Energy's Low-level radioactive waste disposal facilities at the Nevada Test Site transcend those of any other radioactive waste disposal site in the United States. The expanded paper will describe the technical attributes of the facilities, the present and the future disposal capacities and capabilities, and includes a description of the process from waste approval to final disposition. The paper also summarizes the current status of the waste disposal operations.
Date: August 6, 1999
Creator: Bruce D. Becker, Bechtel Nevada; Bruce M. Crowe, Los Alamos National Laboratory; Carl P. Gertz, DOE Nevada & Wendy A. Clayton, DOE Nevada
System: The UNT Digital Library
Grain boundaries and mechanical properties of nanocrystalline diamond films. (open access)

Grain boundaries and mechanical properties of nanocrystalline diamond films.

Phase-pure nanocrystalline diamond thin films grown from plasmas of a hydrogen-poor carbon argon gas mixture have been analyzed regarding their hardness and elastic moduli by means of a microindentor and a scanning acoustic microscope.The films are superhard and the moduli rival single crystal diamond. In addition, Raman spectroscopy with an excitation wavelength of 1064 nm shows a peak at 1438 l/cm and no peak above 1500 l/cm, and X-ray photoelectron spectroscopy a shake-up loss at 4.2 eV. This gives strong evidence for the existence of solitary double bonds in the films. The hardness and elasticity of the films then are explained by the assumption, that the solitary double bonds interconnect the nanocrystals in the films, leading to an intergrain boundary adhesion of similar strength as the intragrain diamond cohesion. The results are in good agreement with recent simulations of high-energy grain boundaries.
Date: August 6, 1999
Creator: Busmann, H.-G.; Pageler, A. & Gruen, D. M.
System: The UNT Digital Library
Polysilicon TFT fabrication on plastic substrates (open access)

Polysilicon TFT fabrication on plastic substrates

Processing techniques utilizing low temperature depositions and pulsed lasers allow the fabrication of polysilicon thin film transistors (TFT`s) on plastic substrates. By limiting the silicon, SiO2, and aluminum deposition temperatures to 100(degrees)C, and by using pulsed laser crystallization and doping of the silicon, we have demonstrated functioning polysilicon TFT`s fabricated on polyester substrates with channel mobilities of up to 7.5 cm2/V-sec and Ion/Ioff current ratios of up to 1x10(to the 6th power).
Date: August 6, 1997
Creator: Carey, P. G.; Smith, P. M.; Wickboldt, P.; Thompson, M. O. & Sigmon, T. W.
System: The UNT Digital Library
Developing solid state experiments on the Nova laser (open access)

Developing solid state experiments on the Nova laser

An x-ray drive has been developed to shock compress metal foils in the solid state using an internally shielded hohlraum with a high contrast shaped pulse from the Nova laser. The drive has been characterized and hydrodynamics experiments designed to study growth of the Rayleigh-Taylor (RT) instability in Cu foils at 3 Mbar peak pressures in the plastic flow regime have been started. Pre-imposed modulations with an initial wavelength of 20-50 {micro}m, and amplitudes of 1.0-2.5 {micro}m show growth consistent with simulations. In the Nova experiments, the fluid and solid states are expected to behave similarly for Cu. An analytic stability analysis is used to motivate an experimental design with an Al foil where the effects of material strength on the RT growth are significantly enhanced. The conditions reached in the metal foils at peak compression are similar to those predicted at the core of the earth.
Date: August 6, 1999
Creator: Chandler, E. A.; Colvin, J. D.; Failor, B. H.; Gold, D. M.; Hauer, A.; Kalantar, D. H. et al.
System: The UNT Digital Library
Physical protection upgrades in Ukraine. (open access)

Physical protection upgrades in Ukraine.

The U.S. DOE is providing nuclear material safeguards assistance in both material control and accountability and in physical protection to several facilities in Ukraine. This paper summarizes the types of physical protection upgrades that have been or are presently being implemented at these facilities. These facilities include the Kiev Institute for Nuclear Research, Kharkov Institute of Physics and Technology, Sevastopol Institute of Nuclear Energy and Industry, and the South Ukraine Nuclear Power Plant. Typical upgrades include: hardening of storage areas; improvements in access control, intrusion detection, and CCTV assessment; central alarm station improvements; and implementation of new voice communication systems. Methods used to implement these upgrades and problems encountered are discussed. Training issues are also discussed.
Date: August 6, 1998
Creator: Djakov, A.
System: The UNT Digital Library
Optical Properties of {beta}''-(ET){sub 2}SF{sub 5}CH{sub 2}CF{sub 2}SO{sub 3} : a novel superconductor with large discrete counterions.'' (open access)

Optical Properties of {beta}''-(ET){sub 2}SF{sub 5}CH{sub 2}CF{sub 2}SO{sub 3} : a novel superconductor with large discrete counterions.''

The optical spectra of the organic superconductor {beta}{double_prime}-(ET){sub 2}SF{sub 5}CH{sub 2}CF{sub 2}SO{sub 3} are measured over a wide spectral range (30-35000 cm{sup {minus}1}) as a function of temperature and polarization. The optical anisotropy is quite large compared with other ET-based organic superconductors, and the spectra are far from Drude-like over the full temperature range. A broad electronic band centered near 1000 cm{sup {minus}1} is observed at low temperature along the a axis, prior to the superconducting transition. The changes of vibrational features near 120 K are attributed to a weak reorientation of the counterion, which may affect hydrogen bonding in the material.
Date: August 6, 1998
Creator: Dong, J.
System: The UNT Digital Library
Slim Holes for Small Power Plants (open access)

Slim Holes for Small Power Plants

Geothermal research study at Sandia National Laboratories has conducted a program in slimhole drilling research since 1992. Although our original interest focused on slim holes as an exploration method, it has also become apparent that they have substantial potential for driving small-scale, off-grid power plants. This paper summarizes Sandia's slim-hole research program, describes technology used in a ''typical'' slimhole drilling project, presents an evaluation of using slim holes for small power plants, and lists some of the research topics that deserve further investigation.
Date: August 6, 1999
Creator: Finger, John T.
System: The UNT Digital Library
Kinetic modeling of non-ideal explosives with CHEETAH (open access)

Kinetic modeling of non-ideal explosives with CHEETAH

We report an implementation of the Wood-Kirkwood kinetic detonation model based on multi-species equations of state and multiple reaction rate laws. Finite rate laws are used for the slowest chemical reactions. Other reactions are given infinite rates and are kept in constant thermodynamic equilibrium. We model a wide range of ideal and non-ideal composite energetic materials. We find that we can replicate experimental detonation velocities to within a few per cent, while obtaining good agreement with estimated reaction zone lengths. The detonation velocity as a function of charge radius is also correctly reproduced.
Date: August 6, 1998
Creator: Fried, L E; Howard, W M & Souers, P C
System: The UNT Digital Library
The magnetic resonance force microscope: A new microscopic probe of magnetic materials (open access)

The magnetic resonance force microscope: A new microscopic probe of magnetic materials

The magnetic resonance force microscope (MRFM) marries the techniques of magnetic resonance imaging (MRI) and atomic force microscopy (AFM), to produce a three-dimensional imaging instrument with high, potentially atomic-scale, resolution. The principle of the MRFM has been successfully demonstrated in numerous experiments. By virtue of its unique capabilities the MRFM shows promise to make important contributions in fields ranging from three-dimensional materials characterization to bio-molecular structure determination. Here the authors focus on its application to the characterization and study of layered magnetic materials; the ability to illuminate the properties of buried interfaces in such materials is a particularly important goal. While sensitivity and spatial resolution are currently still far from their theoretical limits, they are nonetheless comparable to or superior to that achievable in conventional MRI. Further improvement of the MRFM will involve operation at lower temperature, application of larger field gradients, introduction of advanced mechanical resonators and improved reduction of the spurious coupling when the magnet is on the resonator.
Date: August 6, 1997
Creator: Hammel, P. C.; Zhang, Z.; Midzor, M.; Roukes, M. L.; Wigen, P. E. & Childress, J. R.
System: The UNT Digital Library
Analysis and experiments of a whistler-wave plasma thruster (open access)

Analysis and experiments of a whistler-wave plasma thruster

A plasma thruster operating at high specific impulse ({ge} 3500 s) has been proposed to be based on electron-cyclotron resonance heating of whistler waves propagating on a plasma column on a magnetic hill. Calculations using a particle-in-cell code demonstrate that the distortion of the electron velocity distribution by the heating significantly reduces the flow of plasma up the field, greatly improving efficiency and reducing material interactions relative to a thermal plasma. These and other calculations are presented together with initial experiments on the plasma generated in the proposed device. The experiments are conducted in a magnetic field (3.3 {times} 10{sup {minus}2} T at resonance) and a magnetic mirror ratio of 5. Microwaves (0.915 GHz, <20 kW) are coupled to the plasma with a helical antenna. Vacuum field measurements are in good agreement with prediction. The desired plasma spatial distribution has not yet been achieved.
Date: August 6, 1993
Creator: Hooper, E. B.; Ferguson, S. W.; Makowski, M. A.; Stallard, B. W. & Power, J. L.
System: The UNT Digital Library
The OZI rule: A unique selector of glueballs and hadron spectroscopy (open access)

The OZI rule: A unique selector of glueballs and hadron spectroscopy

In the first part of this talk I have reviewed the history of the OZI rule. I then have shown how it is a unique selector glueballs and new quarks in hadron spectroscopy. In particular the only glueball candidates which cannot be explained by other hypotheses within QCD are the I{sup G}J{sup PC} = 0{sup +}2{sup ++} g{sub T}(2010), g{sub T},(2300) and g{sub T{double prime}}(2340) observed in the OZI suppressed reaction {pi}{sup {minus}} p {yields} {phi}{phi}n. The narrowness of the J/{psi} and T can only be explained by OZI suppression. I then reminisced about the 1954 Rochester Conference in which our work on {pi}{sup {plus minus}}p total cross sections and {pi}{sup {plus minus}} production combined gave convincing evidence for the delta being the first resonance. Described how the 1964 Dubna Conference results on small angle {pi}{sup {plus minus}}p elastic scattering led to the first critical experimental check of the pion-nucleon forward dispersion relations which showed that the basic axions of modern field theory worked on strong interactions at high energies. I finally reminisced about glueballs in the 1982 and 1988 Rochester Conferences. 52 refs., 17 figs., 3 tabs.
Date: August 6, 1990
Creator: Lindenbaum, S. J.
System: The UNT Digital Library
Measurements with radioactive beams at ATLAS. (open access)

Measurements with radioactive beams at ATLAS.

Reactions of interest to nuclear astrophysics have been studied with radioactive beams at the ATLAS accelerator. Using a modified ISOL technique, beams of {sup 18}F (T{sub 1/2} = 110 min) and {sup 56}Ni (T{sub 1/2} = 6.1d) were produced and the reactions {sup 18}F(p,{alpha}){sup 15}O, {sup 18}F(p,{gamma}){sup 19}Ne, and {sup 56}Ni(d,p){sup 57}Ni have been investigated. The results indicate that the {sup 18}F(p,{gamma}) route is a small contributor to the breakout from the hot CNO cycle into the rp process, while the {sup 56}Ni(p,{gamma}){sup 57}Cu rate is about ten times larger than previously assumed.
Date: August 6, 1998
Creator: Rehm, K. E.
System: The UNT Digital Library
A new diffractometer for high energy synchrotron radiation at the elliptical multipole wiggler at the APS. (open access)

A new diffractometer for high energy synchrotron radiation at the elliptical multipole wiggler at the APS.

The use of high energy synchrotrons radiation (above 80 keV) for diffraction experiments offers many advantages resulting from the high penetration depth of the high energy photons and the small Bragg angles. The main features are: the possibility for the study of large sample crystals in transmission geometry, simple sample environments, high instrumental resolution in reciprocal space, the ability to utilize high momentum transfers and small correction factors for scattered intensities. The experiments performed at this kind of diffractometer are mainly flux experiments, in which the only requirement is a relatively small angular divergence for the incident beam in the scattering plane. The new triple crystal diffractometer introduced here will be installed at the elliptical multipole wiggler beamline at the Advanced Photon Source (APS), Because of the high critical energy of this device, 32 keV, the wiggler will produce high intensities at very high photon energies. To collect up to 1 mrad of the horizontal divergence of the beam, a bent annealed silicon monochromator will scatter and focus in the horizontal scattering plane. The diffractometer will be operated in the vertical scattering plane taking advantage of the small vertical beam divergence.
Date: August 6, 1998
Creator: Ruett, U.
System: The UNT Digital Library
MGA and passive neutron measurements (open access)

MGA and passive neutron measurements

MGA is a gamma-ray spectrum analysis program for determining relative plutonium isotopic abundances. The isotopic composition of a plutonium sample is needed to calculate {sup 240}Pu{sub eff} that is used to interpret passive neutron coincidence measurements in units of absolute plutonium mass. MGA can determine plutonium isotopic abundances with accuracies better than 1% using a high-resolution, low-energy, planar germanium detector and measurement times ten minutes or less. MGA can include analysis of a second spectrum of the high-energy (300--600 keV) plutonium gamma rays that significantly improves the determination of {sup 240}P{sub eff} in high-burnup plutonium. For the high-energy gamma-ray measurements we have devised a new hardware configuration, so that both the low- and high-energy gamma-ray detectors are mounted in a single cryostat thereby reducing weight and volume of the detector systems. We describe the detector configuration and our experience with it using a combined neutron-gamma measurement system and the two-detector version of MGA. We discuss the sources of uncertainty in the determination of {sup 240}Pu{sub eff} and propose a new correlation for the determination of {sup 242}Pu.
Date: August 6, 1993
Creator: Ruhter, W. D.; Gunnink, R.; Baumann, S.; Abeynaike, S. & Verplancke, J.
System: The UNT Digital Library
Proposed DSS-specific fields for the generic authentication information element (open access)

Proposed DSS-specific fields for the generic authentication information element

This contribution proposes the format of the ``Algorithm-Specific Information`` and ``Signature`` fields within the ``Proposed Generic Authentication Information Element`` for authentication IEs based on the Digital Signature Standard (DSS). These fields are designed to allow various levels of authentication ``strength`` (or robustness), and many of these fields may be omitted in systems that optimize authentication performance by sharing common (public) Digital Signature Algorithm (DSA) parameters. This allows users and site security officers to design their authenticated signaling according to site security and performance requirements.
Date: August 6, 1995
Creator: Tarman, T.D.
System: The UNT Digital Library
Calculating the shrapnel generation and subsequent damage to first wall and optics components for the National Ignition Facility (open access)

Calculating the shrapnel generation and subsequent damage to first wall and optics components for the National Ignition Facility

The purpose of this work is to computationally assess the threat from shrapnel generation on the National Ignition Facility (NIF) first wall, final optics, and ultimately other target chamber components. Shrapnel is defined as material.that is in a solid, liquid, or clustered-vapor phase with sufficient velocity to become a threat to exposed surfaces as a consequence of its impact. Typical NIF experiments will be of two types, low neutron yield shots in which the capsule is not cryogenically cooled, and high yield shots for which cryogenic cooling of the capsule is required. For non-cryogenic shots, shrapnel would be produced by spaIIing, melting and vaporizing of ``shine shields`` by absorption and shock wave loading following 1-{omega} and 2-{omega} laser radiation. For cryogenic shots, shrapnel would be generated through shock wave splitting, spalling, and droplet formation of the cryogenic tubes following neutron energy deposition. Motion of the shrapnel is determined not only by particle velocities resulting from the neutron deposition, but also by both x-ray and debris loading arising from explosion of the hohlraum. Material responses of different target area components are computed from one- dimensional and two-dimensional stress wave propagation codes. Well developed rate-dependent spall computational models are used for stainless …
Date: August 6, 1996
Creator: Tokheim, R. E.; Seaman, L.; Cooper, T.; Lew, B.; Curran, D. R.; Sanchez, J. et al.
System: The UNT Digital Library
Magnetohydrodynamics and Radiation Methods Workshop (open access)

Magnetohydrodynamics and Radiation Methods Workshop

None
Date: August 6, 1998
Creator: Winske, D.
System: The UNT Digital Library
The National Facility physics and diagnostics (open access)

The National Facility physics and diagnostics

This paper presents a description of the National Ignition Facility, some of the physics experiments that will be performed on it and a description of some of the diagnostics needed to complete these experiments. Experiments are presented under the headings of: ignition physics, weapons physics or high-energy-density experimental science, weapons effects, and basic science and inertial fusion energy. The diagnostics discussed are primarily those that will be provided for early operation.
Date: August 6, 1999
Creator: Wooton, A
System: The UNT Digital Library
The national facility physics and diagnostics (open access)

The national facility physics and diagnostics

This paper presents a description of the National Ignition Facility, some of the physics experiments that will be performed on it and a description of some of the diagnostics needed to complete these experiments. Experiments are presented under the headings of: ignition physics, weapons physics or high-energy-density experimental science, weapons effects, and basic science and inertial fusion energy. The diagnostics discussed are primarily those that will be provided for early operation.
Date: August 6, 1999
Creator: Wootton, A
System: The UNT Digital Library
The National Facility physics and diagnostics (open access)

The National Facility physics and diagnostics

This paper presents a description of the National Ignition Facility, some of the physics experiments that will be performed on it, and a description of some of the diagnostics needed to complete these experiments. Experiments are presented under the headings of: ignition physics, weapons physics or high-energy-density experimental science, weapons effects, and basic science and inertial fusion energy. The diagnostics discussed are primarily those that will be provided for early operation.
Date: August 6, 1999
Creator: Wootton, A.
System: The UNT Digital Library