An asymmetric muon-proton Collider: Luminosity Consideration (open access)

An asymmetric muon-proton Collider: Luminosity Consideration

An asymmetric muon-proton collider is proposed as an instrument for possible quark structure search. Energy of proton beam is supposed to be some 5-6 times of muon energy. Estimated luminosity of the collider with two rings--the Tevatron accelerator and {mu}-ring--is found to be of the order of 10{sup 33} s{sup -1} cm{sup -2}.
Date: April 1, 1997
Creator: Shiltsev, V. D.
System: The UNT Digital Library
Supersymmetric lepton flavor violation at the NLC (open access)

Supersymmetric lepton flavor violation at the NLC

Supersymmetric theories generally have new flavor violation sources in the squark and slepton mass matrices. If significant lepton flavor violation exists, selectron and smuon should be nearly degenerate. This leads to the phenomenon of slepton oscillations, which is analogous to neutrino oscillations, if sleptons are produced at the Next Linear Collider. The direct slepton production at the Next Linear Collider provides a much more powerful probe of lepton flavor violation than the current bounds from rare processes, such as {mu} {yields} e{gamma}.
Date: April 1, 1997
Creator: Cheng, Hsin-Chia
System: The UNT Digital Library
Effect of jitter on an imaging FTIR spectrometer (open access)

Effect of jitter on an imaging FTIR spectrometer

Line of sight (LOS) jitter produces temporal modulations of the signals which are detected in the focal plane of a temporally modulated imaging Fourier Transform Spectrometer. A theoretical treatment of LOS jitter effects is given, and is compared with the results of measurements with LIFTIRS1 (the Livermore Imaging Fourier Transform InfraRed Spectrometer). The identification, isolation, quantification and removal of jitter artifacts in hyperspectral imaging data by means of principal components analysis is discussed. The theoretical distribution of eigenvalues expected from principal components analysis is used to determine the level of significance of spatially coherent instrumental artifacts in general, including jitter as a representative example. It is concluded that an imaging FTIR spectrometer is much less seriously impacted by a given LOS jitter level than a non imaging FTIR spectrometer.
Date: April 1, 1997
Creator: Bennett, C. L., LLNL
System: The UNT Digital Library
Search for flavor changing neutral current decays of the top quark in p {anti p} collisions at {radical} s = 1.8 TeV (open access)

Search for flavor changing neutral current decays of the top quark in p {anti p} collisions at {radical} s = 1.8 TeV

None
Date: April 1, 1997
Creator: LeCompte, Thomas J.
System: The UNT Digital Library
Solvent reorganization energies measured by an electron transfer reaction in supercritical ethane. (open access)

Solvent reorganization energies measured by an electron transfer reaction in supercritical ethane.

The intermolecular electron transfer reaction between a biphenyl anion and pyrene in supercritical ethane was studied using pulse radiolysis. Second-order electron transfer rates were found to be of the order of 10{sup 11} M{sup {minus}1} s{sup {minus}1}. The rate constants appear to be approximately constant over the pressure range 55-133 bar. Two possibilities are discussed that could explain the present results: solvent clustering; or a dependence of the solvent reorganization energy on pressure. Reorganization energies E{sub r} of non-polar supercritical ethane were estimated from the observed rate constant using the modified Marcus equation. E{sub r} may be larger than normally expected for non-polar solvents because of density fluctuations.
Date: April 14, 1997
Creator: Feng, W.; Jonah, C. D.; Sawamura, S. & Takahashi, K.
System: The UNT Digital Library
Detection of 99Tc by accelerator mass spectrometry: preliminary investigations (open access)

Detection of 99Tc by accelerator mass spectrometry: preliminary investigations

Accelerator mass spectrometry is an established technique for the detection of long-lived radionuclides at environmental levels. At LLNL, planned facility upgrades and advances in detection techniques are allowing us to explore the applicability of AMS to isotopes not previously pursued. One such isotope is technetium-99. We have performed a number of preliminary tests to examine the technical feasibility of AMS for the detection of {sup 99}Tc. The questions addressed were negative ion production in the cesium sputter source, transport efficiency for the ions through the spectrometer, and detection efficiency for {sup 99}Tc ions after the spectrometer. Based on the positive results of these tests, we have begun to develop a measurement protocol. Technetium is co-precipitated with rhodium, added as a carrier, which provides a sample form appropriate for sputtering and an isotope for AMS normalization. The {sup 99}Tc is determined from the measured {sup 99}Tc/{sup 103}Rh ratio. To reduce interference from the isobar {sup 99}Ru, an oxidation/distillation method was employed to lower ruthenium in the rhodium stock solution. Characteristic projectile L x-rays are used for ion detection to allow further subtraction of {sup 99}Ru. Results for a series of standards demonstrated linearity and reproducibility. A sensitivity of {approx}500 fg {sup …
Date: April 1, 1997
Creator: McAninch, J. E.
System: The UNT Digital Library
Magnetic circular x-ray dichroisms of Fe-Ni alloys at K edge. (open access)

Magnetic circular x-ray dichroisms of Fe-Ni alloys at K edge.

Magnetic Circular X-ray Dichroism (MCXD) studies at K edges of Fe-Ni alloys reveal changes of the MCXD signal with composition and crystal structure. We observe that the signal at the invar composition is of comparable strength as other compositions. Moreover, the edge position is strongly dependent on lattice constant. First principles calculations demonstrate that the shape and strength of the signal strongly depends on the crystal orientation, composition, and lattice constant. We find direct relation between the MCXD signal and the p DOS. We find that the MCXD at K edge probes the magnetism due to itinerant electrons.
Date: April 3, 1997
Creator: Freeman, A. J.; Gofron, K. J.; Kimball, C. W.; Lee, P. L.; Montano, P. A.; Rao, F. et al.
System: The UNT Digital Library
The CDF SVX II upgrade for the Tevatron Run II (open access)

The CDF SVX II upgrade for the Tevatron Run II

A microstrip silicon detector SVX II has been proposed for the upgrade of CDF to be installed in 1999 for Run II of the Tevatron. Three barrels of five layers of double-sided silicon microstrip detectors will cover the interaction region. A description of the project status will be presented. Emphasis will be given to the R&D program for silicon sensors which includes capacitance minimization, the study of coupling capacitor integrity, the operation of the detectors in conjunction with the SVXH and SVX2 readout chips in two beam tests and the determination of the detectors performance deterioration due to radiation damage.
Date: April 1, 1997
Creator: Bortoletto, Daniela
System: The UNT Digital Library
Fundamental limits on NOx reduction by plasma (open access)

Fundamental limits on NOx reduction by plasma

This paper discusses the gas-phase reaction mechanisms for removal of NO{sub x} in a plasma. The effect of oxygen content on the competition between the reduction and oxidation processes is discussed. The effect of the electron kinetic energy distribution on the radical production and subsequent chemistry is then discussed in order to predict the best performance that can be achieved for NO{sub x} reduction using the plasma alone. The fundamental limit on the minimum electrical energy consumption that will be required to implement NO{sub x} reduction in any type of plasma reactor is established.
Date: April 7, 1997
Creator: Penetrante, B. M., LLNL
System: The UNT Digital Library
Marine reactor pressure vessels dumped in the Kara Sea (open access)

Marine reactor pressure vessels dumped in the Kara Sea

None
Date: April 21, 1997
Creator: Mount, M. E.; Warden, J. M.; Lynn, N. M. & Timms, S. J.
System: The UNT Digital Library
The ATLAS level 2 trigger supervisor. (open access)

The ATLAS level 2 trigger supervisor.

This paper presents an overview of the hardware and software proposed for the ATLAS level 2 Trigger ROI Builder/Supervisor. The essential requirements of this system are that it operate at the design Level 1 Trigger rate of 100kHz and that it support the technical requirements of the architectures suggested for the ATLAS Level 2 Trigger. Commercial equipment and software support are used to the maximum extent possible, with support from dedicated hardware. Timing requirements and latencies are discussed and simulation results are presented.
Date: April 3, 1997
Creator: Abolins, M.; Blair, R. E.; Dawson, J. W.; Owen, D.; Pope, B. G.; Schlereth, J. L. et al.
System: The UNT Digital Library
{ital Ab Initio} Pseudopotential calculations of dopant diffusion in Si (open access)

{ital Ab Initio} Pseudopotential calculations of dopant diffusion in Si

The ab initio pseudopotential method is used to study transient-enhanced-diffusion (TED) related processes. The electronic degrees of freedom are included explicitly, together with the fully self-consistent treatment of the electron charge density. A large supercell and a fine k-point mesh are used to ensure numerical convergence. Such method has been demonstrated to give quantitative description of defect energetic. We will show that boron diffusion is significantly enhanced in the presence of the Si interstitial due to the substantial lowering of the migrational barrier through a kick-out mechanism. The resulting mobile boron can also be trapped by another substitutional boron, forming an immobile and elect rically inactive two-boron pair. Similarly, carbon diffusion is also enhanced significantly due to the pairing with Si interstitial. However, carbon binds to Si interstitial much more strongly than boron does, taking away most Si interstitial from boron at sufficiently large carbon concentration, which causes the suppression of the boron TED. We will also show that Fermi level effect plays an important role in both Si interstitial and boron diffusion.
Date: April 28, 1997
Creator: Zhu, J., LLNL
System: The UNT Digital Library
Analysis of Thomsen Parameters for Finely Layered Vti Media (open access)

Analysis of Thomsen Parameters for Finely Layered Vti Media

The range of Thomsen`s anisotropy parameters {epsilon} and {delta} for vertical transversely isotropic (VTI) media when the anisotropy is due to fine layering of isotropic elas-tic materials is considered. We show that {epsilon} lies in the range -3/8 {<=} {epsilon} {<=} {1/2}[<v{sub p}{sup 2}><v{sup p}{sup -2}>-1], for finely lay-ered media having constant density; smaller positive and all negative values of {epsilon} occur for media with large fluctuations in the Lam{acute e} parameter {lambda} We show that sign({delta}) = sign (<v{sub p}{sup -2}> - <v{sub s}{sup -2}><v{sub s}{sup 2}/v{sub p}{sup 2}>) for constant density media, so {delta} can be either positive or negative. Among all theoretically possible random media, posi-tive and negative {delta} are equally likely in finely layered media limited to two types of constituent layers. Lay-ered media having large fluctuations in Lam{acute e} {lambda} are the ones most likely to have positive {delta}. Since Gassmann`s results for fluid-saturated porous media show that the effects of fluids influence only the {lambda} Lam{acute e} constant, not the shear modulus {mu}, these results suggest that positive {delta} occurring together with positive but small {epsilon} may be indicative of changing fluid content in layered earth.
Date: April 1, 1997
Creator: Berryman, J. G. & Berge, P. A.
System: The UNT Digital Library
Deposition of field emissions cathodes over large areas (open access)

Deposition of field emissions cathodes over large areas

Field emission cathodes (FECs) with characteristics of cold emission, low voltage operation, high current density and microscopic size meet the requirements for an electron source for use in vacuum microelectronics. Deposition efforts have focused on evaporation techniques, as electron beam, to produce the size and shape of cathode required for efficient operation. After two decades of development, the convention for FEC synthesis involves coating with very high tolerances for thickness uniformity using a planetary substrate fixture and a long source-to-substrate distance. A further reduction in the operating voltage results by increasing the density of emitters through a reduction of cathode size and spacing. In addition, the objective of scaling the substrate size from small to large areas has compounded the manufacturing requirements to a point beyond that which is obtainable through modifications to the conventional FEC deposition process. We have been successful in a new alternative approach to design, assemble and operate a system that enables FEC synthesis over large areas through the control of deposition source divergence and step-and-repeat substrate handling.
Date: April 3, 1997
Creator: Jankowski, Alan Frederic & Hayes, Jeffrey P.
System: The UNT Digital Library
RR lyrae in front of the LMC; implications for microlensing (open access)

RR lyrae in front of the LMC; implications for microlensing

The recent suggestion that the microlensing events observed towards the Large Magellanic Cloud are due to an intervening Sgr-like dwarf galaxy is examined. A search for foreground RR Lyrae in the MACHO photometry database yields 20 stars whose distance distribution is not concentrated, and follows the expected halo density profile. Cepheid and red giant branch clump stars in the MACHO database are consistent with membership in the LMC. Since (equal to or less than) 0.3 percent of the RR Lyrae and Cepheids are in the foreground, we conclude that the observed microlensing optical depth is not due to an intervening dwarf galaxy.
Date: April 1, 1997
Creator: Minniti, D.; Aleves, D. A. & Alcock, C.
System: The UNT Digital Library
Method for rapid, high sensitivity tritiated water extraction (open access)

Method for rapid, high sensitivity tritiated water extraction

We have developed a thermal vacuum desorption process to rapidly extract water from environmental samples for tritium analysis. Thermal vacuum desorption allows for extraction of the moisture from the sample within a few hours in a form and quantity suitable for liquid scintillation counting and allows detection of tritium at the levels of <2 Bq/L of milk, <0.5 Bq/gm of vegetation, and < 0.5 Bq/gin of soil. We developed a prototype unit that can process batches of twenty or more samples within 24 hours. Early data shows that a high percentage of water is extracted reproducibly without enrichment or depletion of the tritium content. The quench coefficient of the extracted water is low allowing for accurate, direct liquid scintillation counting. Excellent comparison has been observed with results using freeze-dry lypholization as the water extraction method.
Date: April 20, 1997
Creator: Failor, R.; Belovodsky, L.; Gaevoy, V. & Golubev, A.
System: The UNT Digital Library
Petawatt laser system and targeting performance (open access)

Petawatt laser system and targeting performance

We recently demonstrated the production of 1.25 PW of peak power in the Nova/Petawatt Laser Facility, generating > 600 J in < 450 fs. Results of the first focused irradiance tests, at 500 J and deployment of a novel targeting system will be presented.
Date: April 30, 1997
Creator: Pennington, D.M.; Perry, M.D. & Britten, J.A.
System: The UNT Digital Library
Diffraction-limited, high average power phase-locking of four 30J beams from discrete Nd:glass zig-zag amplifiers (open access)

Diffraction-limited, high average power phase-locking of four 30J beams from discrete Nd:glass zig-zag amplifiers

A single ND:YLF oscillator beam is amplified in four discrete Nd:glass, flashiamp-pumped, zig-zag amplifiers. The resulting four 30J beams are phase- locked using SBS phase conjugation, resulting in near diffraction-limited 120J pulses from a single aperture at up to a 1 OHz pulse repetition frequency.
Date: April 24, 1997
Creator: Dane, C. B.; Wintemute, J. D.; Bhachu, B. & Hackel, L. A.
System: The UNT Digital Library
Bridging the Cold War and the 21st century: chronicling the history of Sandia National Laboratories (open access)

Bridging the Cold War and the 21st century: chronicling the history of Sandia National Laboratories

A historical perspective is given for Sandia National Laboratories from its beginnings as a small engineering group at an offshoot of Los Alamos Laboratory to a facility of 7000 people at its main facility in Albuquerque, another 1000 people in Livermore, California and test ranges in Tonopah, Nevada and Kauai, Hawaii. The Sandia army base became the Z division of Los Alamos and $25 million construction program began the structures that would carry out a test program for nuclear weapons during the cold war. Bell System/AT&T stewardship of the site continued from 1949 to 1993, when Martin Marietta (now Lockheed Martin) was chosen as the new contractor. Management decisions, personnel, and political aspects of the Laboratory are presented up to 1997 and forecasts are given for future policy and programs of Sandia.
Date: April 1, 1997
Creator: Mora, C.J.
System: The UNT Digital Library
The oxide defined VCSEL-based smart pixels for the optical database filter (open access)

The oxide defined VCSEL-based smart pixels for the optical database filter

This paper presents the construction of the smart pixel arrays which perform AND and XOR functions with three-input and one-output optical signals for the application of an optical database filter. The device is based on oxide confined VCSELs bump bonded to GaAs MESFET pixels. The MSM photodetectors are monolithically integrated with MESFETs.
Date: April 1, 1997
Creator: Pu, R.; Hayes, E.; Jurrat, R.; Stanko, P.J.; Wilmsen, C.W.; Choquette, K. et al.
System: The UNT Digital Library
Frequency conversion of high peak and high average power lasers (open access)

Frequency conversion of high peak and high average power lasers

We examine the potential performance of existing materials for frequency conversion of a 10 Hz, 10 ns, I kilowatt average power laser.
Date: April 28, 1997
Creator: Ebbers, C. A.
System: The UNT Digital Library
Status of the National Ignition Facility project (open access)

Status of the National Ignition Facility project

The ultimate goal of worldwide research in inertial confinement fusion (ICF) is to develop fusion as an inexhaustible, economic, environmentally safe source of electric power. Following nearly thirty years of laboratory and underground fusion experiments, the next step toward this goal is to demonstrate ignition and propagating burn of fusion fuel in the laboratory. The National Ignition Facility(NIF) Project is being constructed at Lawrence Livermore National Laboratory (LLNL), for just this purpose. NIF will use advanced Nd-glass laser technology to deliver 1.8 MJ of 0.35-um laser light in a shaped pulse, several nanoseconds in duration, achieving a peak power of 500 TW. A national community of U.S. laboratories is participating in this project, now in its final design phase. Franceand the United Kingdom are collaborating on development of required technology under bilateral agreements with the US. This paper presents thestatus of the laser design and development of its principal components and optical elements.
Date: April 1, 1997
Creator: Paisner, J.A.; Lowdermilk, W.H.; Boyes, J.D.; Sorem, M.S. & Soures, J.M.
System: The UNT Digital Library
Rosat-Green bank sample of intermediate BL Lac objects (open access)

Rosat-Green bank sample of intermediate BL Lac objects

The Rosat-GreenBank BLLac sample consists of 119 objects and smoothly bridges the gap between the previously disparate subclasses of radio- and X-ray-selected objects. Further study of this sample should provide useful constraints to the unified scheme and help determine if modifications are necessary.
Date: April 1, 1997
Creator: Laurent-Muchleisen, S.A.; Kollgaurd, R.I. & Feigelson, E.D.
System: The UNT Digital Library