Resource Type

235 Matching Results

Results open in a new window/tab.

B-Quark Inclusive Cross Sections and B{Bar B} Correlations Using Dimuons From the D0 Experiment (open access)

B-Quark Inclusive Cross Sections and B{Bar B} Correlations Using Dimuons From the D0 Experiment

Using dimuons collected with the D{null} detector during the 1993- 1995 Tevatron collider run, we have measured the {ital b}-quark cross section and {ital b{anti b}} correlations as given by the difference in azimuthal angle between the two muons. Both measurements agree with the NLO QCD predictions within experimental and theoretical errors.
Date: November 1, 1996
Creator: Vititoe, D. L.
System: The UNT Digital Library
D0 papers on B-physics submitted to DPF '96: b-quark inclusive cross sections and b anti-b correlations using dimuons from the D0 experiment; Single muon production in the forward region at [radical]s=1. 8 TEV; Rapidity dependence of the inclusive J[psi] production in the forward region [radical]s=1. 8 TEV; A search for b [r arrow] X[mu][sup +][mu][sup [minus]] and B[sup 0] [r arrow] [mu][sup +][mu][sup [minus]] decays in p anti-p collisions at [radical]s=1. 8 TEV (open access)

D0 papers on B-physics submitted to DPF '96: b-quark inclusive cross sections and b anti-b correlations using dimuons from the D0 experiment; Single muon production in the forward region at [radical]s=1. 8 TEV; Rapidity dependence of the inclusive J[psi] production in the forward region [radical]s=1. 8 TEV; A search for b [r arrow] X[mu][sup +][mu][sup [minus]] and B[sup 0] [r arrow] [mu][sup +][mu][sup [minus]] decays in p anti-p collisions at [radical]s=1. 8 TEV

Paper 1: Using dimuons collected with the D0 detector during the 1993--1995 Tevatron collider run, the authors have measured the b-quark cross section and b[anti b] correlations as given by the difference in azimuthal angle between the two muons. Both measurements agree with the NLO QCD predictions within experimental and theoretical errors. (Three other papers are included in this report.)
Date: November 1, 1996
Creator: Vititoe, D.L. (Arizona Univ., Tucson, AZ (United States). Dept. of Physics); Kozelov, Alexander; Jesik, Richard & Collaboration., D0
System: The UNT Digital Library
Wakimoto realizations of current algebras: an explicit construction (open access)

Wakimoto realizations of current algebras: an explicit construction

A generalized Wakimoto realization of $\widehat\cal G_K$ can be associated with each parabolic subalgebra $\cal P=(\cal G_0 +\cal G_+)$ of a simple Lie algebra $\cal G$ according to an earlier proposal by Feigin and Frenkel. In this paper the proposal is made explicit by developing the construction of Wakimoto realizations from a simple but unconventional viewpoint. An explicit formula is derived for the Wakimoto current first at the Poisson bracket level by Hamiltonian symmetry reduction of the WZNW model. The quantization is then performed by normal ordering the classical formula and determining the required quantum correction for it to generate $\widehat\cal G_K$ by means of commutators. The affine-Sugawara stress-energy tensor is verified to have the expected quadratic form in the constituents, which are symplectic bosons belonging to $\cal G_+$ and a current belonging to $\cal G_0$. The quantization requires a choice of special polynomial coordinates on the big cell of the flag manifold $P\backslash G$. The effect of this choice is investigated in detail by constructing quantum coordinate transformations. Finally, the explicit form of the screening charges for each generalized Wakimoto realization is determined, and some applications are briefly discussed.
Date: November 12, 1996
Creator: de Boer, Jan & Feher, Laszlo
System: The UNT Digital Library
Toward optimization of the grain boundary character distribution in copper by strain annealing (open access)

Toward optimization of the grain boundary character distribution in copper by strain annealing

We have used a two step (low and high temperature) strain-annealing process to evolve the two grain boundary character distribution (GBCD) in fully recrystallized oxygen (OFE) copper bar that was forged and rolled. Orientation imaging microscopy (OIM) has been used to characterize the GBCD after each step in the processing. The fraction of special grain boundaries, special fraction was about 70% in the starting recrystallized material. Three different processing conditions were employed: high, moderate, and low temperature. The high temperature process resulted in a reduction in the fraction of special grain boundaries while both of the lower temperature processes resulted in an increase in special fraction up to 85%. Further, the lower temperature processes resulted in average deviation angles from exact misorientation, for special boundaries, that were significantly smaller than observed from the high temperature process. Results indicate the importance of low temperature part of the two-step strain-annealing process in preparing the microstructure for the higher-temperature anneal and commensurate increase in the special fraction.
Date: November 10, 1996
Creator: King, W.E. & Schwartz, A.J.
System: The UNT Digital Library
CONCLUSIONS OF THE WORKSHOP [Hadron Colliders at the highest energy and luminosity] (open access)

CONCLUSIONS OF THE WORKSHOP [Hadron Colliders at the highest energy and luminosity]

During this Workshop, it was concluded that a Proton-Proton Collider with an energy of 100 TeV per beam and a luminosity of about 10{sup 35} cm{sup {minus}2} s{sup {minus}1} is feasible. The most important technical requirement for the realization of such a project is a large bending field. For instance, a field of 13 Tesla would be desirable. This is twice the field of the SSC superconducting magnets, which very likely may be achieved in a non-too-far future by extrapolation of the present technology. The design of this Collider would follow very closely the methods used for the design of the SSC and of the LHC, with the major noticeable difference that, because of the larger bending field and the larger beam energy, the performance is determined by the effects of the Synchrotron Radiation in the similar manner they affect the performance of an electron-positron collider. This fact has considerable beneficial consequences since it allows the attainment of large luminosity by reducing the beam dimensions at collision and by requiring, to some degree, less number of particles per beam. On the other end. the losses to synchrotron radiation are to be absorbed by the cryogenic system, and the vacuum system …
Date: November 4, 1996
Creator: Ruggiero, Alessandro G.
System: The UNT Digital Library
Design Considerations and Expectations of a Very Large Hadron Collider (open access)

Design Considerations and Expectations of a Very Large Hadron Collider

The ELOISATRON Project is a proton-proton collider at very high energy and very large luminosity. The main goal is to determine the ultimate performance that is possible to achieve with reasonable extrapolation of the present accelerator technology. A complete study and design of the collider requires that several steps of investigations are undertaken. The authors count five of such steps as outlined in the report.
Date: November 4, 1996
Creator: Ruggiero, A. G.
System: The UNT Digital Library
Elastic-plastic strain acceptance criterion for structures subject to rapidly applied transient dynamic loading (open access)

Elastic-plastic strain acceptance criterion for structures subject to rapidly applied transient dynamic loading

Rapidly applied transient dynamic loads produce stresses and deflections in structures that typically exceed those from static loading conditions. Previous acceptance criteria for structures designed for rapidly applied transient dynamic loading limited stresses to those determined from elastic analysis. Different stress limits were established for different grades of structure depending upon the amount of permanent set considered acceptable. Structure allowed to sustain very limited permanent set is designed to stress limits not significantly greater than yield stress. Greater permanent set in structure under rapidly applied transient dynamic loading conditions is permitted by establishing stress limits that are significantly greater than yield stress but still provide adequate safety margin (with respect to failure). This paper presents a strain-based elastic-plastic (i.e., inelastic) analysis criterion developed as an alternative to the more conservative stress-based elastic analysis stress criterion for structures subjected to rapidly applied transient dynamic loading. The strain limits established are based on a fraction of the strain at ultimate stress obtained from an engineering stress/strain curve of the material. Strains limits are categorized by type as membrane or surface and by region as general, local, or concentrated. The application of the elastic-plastic criterion provides a more accurate, less conservative design/analysis basis …
Date: November 1, 1996
Creator: Solonick, W.
System: The UNT Digital Library
Interoperable, life-cycle tools for assuring building performance: An overview of a commercial building initiative (open access)

Interoperable, life-cycle tools for assuring building performance: An overview of a commercial building initiative

A key impediment to improving the energy efficiency and reducing the environmental impact of buildings is the complexity and cost of managing information over the life cycle of a building. A surprisingly large fraction of the total cost of buildings is embodied in the decision making and information management process due to the structure of the building industry, the numerous people and companies involved in the process, the current nature of the building acquisition process, and the long time periods over which buildings operate once design and construction are completed. The authors suggest that new interoperable software tools could greatly facilitate and rationalize this complex process, thereby reducing time and cost, and greatly improving the habitability and environmental impact of these buildings. They describe a series of projects in which they are building and testing several prototype toolkits as part of a building life-cycle information system that will allow interoperable software tools to function more effectively throughout the design, construction, commissioning, and operations phases.
Date: November 1, 1996
Creator: Selkowitz, S.; Piette, M. A.; Papamichael, K.; Sartor, D.; Hitchcock, R. & Olken, F.
System: The UNT Digital Library
Compendium of Equations for the Design of a Very Large Hadron Collider (open access)

Compendium of Equations for the Design of a Very Large Hadron Collider

In the following the authors give several relationships which are used for the preliminary design and to estimate the collider performance. They limit to the case of the performance during storage and colliding mode. Two of such relations are the relation between bending field B, the bending radius {rho} and the proton momentum p B (Tesla) {rho} (meter) = 3.3356 p (GeV/c) and the minimum requirement of the collider luminosity L which scales with the beam energy E according to L = (10{sup 33} cm{sup {minus}2} s{sup {minus}1}) (E/20 TeV ). They assume that the collider is made of two identical intersecting rings where the two beams circulate in opposite directions otherwise with identical configuration, dimensions and intensity. Both beams are bunched. They also assume, for simplicity, that the beams are round, that is they have the same betatron emittance in the two transverse planes of oscillations, horizontal and vertical. Also the two beams are exactly round at the interaction point where the lattice functions {beta}* has also the same values in the two planes.
Date: November 4, 1996
Creator: RUGGIERO, A. G.
System: The UNT Digital Library
Topcolor (open access)

Topcolor

We review a class of dynamical models in which top condensation occurs at the weak scale, giving rise to the large top quark mass and other phenomena. This typically requires a color embedding, SU(3){sub c} {yields} SU(3){sub 1} x SU(3){sub 2}, ergo ``Topcolor.`` Topcolor suggests a novel route to technicolor models in which sequential quarks condense under the Topcolor interaction to break electroweak symmetries.
Date: November 1, 1996
Creator: unknown
System: The UNT Digital Library
To reveal the quark structure of matter (open access)

To reveal the quark structure of matter

The author presents a overview of some central issues facing strong interaction physics today, with an emphasis on questions that will be addressed in concert by CEBAF at Jefferson Lab and by the new DAPHNE machine at Frascati Lab.
Date: November 1, 1996
Creator: Isgur, Nathan
System: The UNT Digital Library
First look at the new ARAC dispersion model (open access)

First look at the new ARAC dispersion model

We describe a new atmospheric dispersion model being developed for the emergency response system of the US Department of Energy`s Atmospheric Release Advisory Capability (ARAC). This model solves the turbulent, advection-diffusion equation via a Lagrangian particle, Monte-Carlo method. Within a simulation, particles representing the pollutant are moved through the domain using a random displacement method to model the turbulent diffusion and a Runge-Kutta method to model the advection. The bottom boundary in the new model is a union of bilinear surfaces between gridded terrain data rather than the discontinuous `stair step` representation of terrain used previously in the ARAC. The new model accepts winds on (x,y,o) grids that can be horizontally and vertically graded and nested in the horizontal.
Date: November 1, 1996
Creator: Leone, J. M. Jr.; Nasstrom, J. S. & Maddix, D. M.
System: The UNT Digital Library
Trading Studies of a Very Large Hadron Collider (open access)

Trading Studies of a Very Large Hadron Collider

The authors have shown that the design of the ELOISATRON can be approached in five separate steps. In this report they deal with the two major issues of the collider: the size and the strength of the superconducting magnets. The reference design of the SSC calls for a collider circumference of 86 km. It represents the largest size that until recently was judged feasible. The reference design of the LHC requires a bending field of 9 Tesla, that industries are presently determined to demonstrate. Clearly the large size of the project presents problem with magnet tolerances, and collider operation and management. The high field of the superconducting magnets needs to be demonstrated, and the high-field option in excess of 9 Tesla requires extensive research and development. It is obvious from the start that, if the ELOISATRON has to allow large beam energies, the circumference has also to be larger than that of the SSC, probably of few hundred kilometers. On the other end, Tevatron, RHIC and SSC type of superconducting magnets have been built and demonstrated on a large scale and proven to be cost effective and reliable. Their field, nevertheless, hardly can exceed a value of 7.5 Tesla, without …
Date: November 4, 1996
Creator: Ruggiero, A. G.
System: The UNT Digital Library
Progress toward a performance based specification for diamond grinding wheels (open access)

Progress toward a performance based specification for diamond grinding wheels

This work sought to improve the communication between users and makers of fine diamond grinding wheels. A promising avenue for this is to formulate a voluntary product standard that comprises performance indicators that bridge the gap between specific user requirements and the details of wheel formulations. We propose a set of performance specifiers of figures-of-merit, that might be assessed by straightforward and traceable testing methods, but do not compromise proprietary information of the wheel user of wheel maker. One such performance indicator might be wheel hardness. In addition we consider technologies that might be required to realize the benefits of optimized grinding wheels. A non-contact wheel-to- workpiece proximity sensor may provide a means of monitoring wheel wear and thus wheel position, for wheels that exhibit high wear rates in exchange for improved surface finish.
Date: November 12, 1996
Creator: Taylor, J. S.; Piscotty, M. S. & Blaedel, K. L.
System: The UNT Digital Library
Fiber amplifiers and lasers in Yb:silica (open access)

Fiber amplifiers and lasers in Yb:silica

We have measured gain and saturation in sing;e mode Yb:silica fiber, and developed fiber lasers and amplifiers at 1053 nm. The lasers are tunable over 10`s of nanometers, with amplifier gain flattened by fiber gratings or dielectric filters.
Date: November 15, 1996
Creator: Wilcox, R. B.; Browning, D. F.; Feit, M. D. & Nyman, B.
System: The UNT Digital Library
New model for generating mass-consistent wind fields over continuous terrain (open access)

New model for generating mass-consistent wind fields over continuous terrain

Based on a mixed variational principle and the finite element method, a model for efficiently generating mass-consistent wind fields over continuous terraing has been developed. Two numerical examples are presented to demonstrate the applicability of the model.
Date: November 1, 1996
Creator: Chan, Stevens T. & Sugiyama, Gayle
System: The UNT Digital Library
Laser-Induced Fluorescence and Mass Spectrometric Studies of the Cu + HCl Reaction over a Wide Temperature Range. Formation of HCuCl (open access)

Laser-Induced Fluorescence and Mass Spectrometric Studies of the Cu + HCl Reaction over a Wide Temperature Range. Formation of HCuCl

Article on laser-induced fluorescence and mass spectrometric studies of the Cu + HCl reaction over a wide temperature range and the formation of HCuCl.
Date: November 7, 1996
Creator: Belyung, David P.; Hranisavljevic, Jasmina; Kashireninov, Oleg E.; Santana, G. Mauricio; Fontijn, A. (Arthur) & Marshall, Paul
System: The UNT Digital Library
Effect of Radiation on Topopah Spring Tuff Mechanical Properties (open access)

Effect of Radiation on Topopah Spring Tuff Mechanical Properties

The effect of radiation on the mechanical properties of Topopah Spring tuff was investigated by performing uniaxial compressive tests on irradiated and control samples of the tuff from the potential repository horizon at Yucca Mountain. Test results are presented, including stress-strain curves and peak strength and Young`s modulus values. These results show that for homogeneous uncracked samples of Topopah Spring tuff, exposure to gamma radiation had no discernible effect on the unconfined partially healed subvertical caracks indicate that exposure may reduce the strength and Young`s modulus significantly. This is attributed to weakening of the cementing materials in the cracks and fractures of the samples that were irradiated. These results are preliminary, and additional studies are warranted to evaluate whether radiation weakens cementing materials in welded tuff.
Date: November 1, 1996
Creator: Berge, P. A. & Blair, S. C.
System: The UNT Digital Library
Simulations of Laser Imprint for Nova Experiments and for Ignition Capsules (open access)

Simulations of Laser Imprint for Nova Experiments and for Ignition Capsules

In direct drive ICF, nonuniformities in laser illumination seed ripples at the ablation front in a process called imprint. These non nonuniformities grow during the capsule implosion and, if initially large enough, can penetrate the capsule shell, impede ignition, or degrade burn. Imprint has been simulated for recent experiments performed on the Nova laser at LLNL examining a variety of beam smoothing conditions. Most used laser intensities similar to the early part of an ignition capsule pulse shape, I=10X13 W/cm3. The simulations matched most of the measurements of imprint modulation. The effect of imprint upon National Ignition Facility (NIF) direct drive ignition capsules has also been simulated. Imprint is predicted to give modulation comparable to an intrinsic surface finish of 10 nm RMS. Modulation growth was examined using the Haan model, with linear growth as a function of spherical harmonic mode number obtained from an analytic dispersion relation. Ablation front amplitudes are predicted to become substantially nonlinear, so that saturation corrections are large. Direct numerical simulations of two- dimensional multimode growth were also performed. The capsule shell is predicted to remain intact, which gives a basis for believing that ignition can be achieved.
Date: November 8, 1996
Creator: Weber, S. V.; Glendinning, S. G.; Kalantar, D. H.; Key, M. H.; Remington, B. A.; Rothenberg, J. E. et al.
System: The UNT Digital Library
Concept for high-charge-state ion induction accelerators (open access)

Concept for high-charge-state ion induction accelerators

This work describes a particular concept for ion induction linac accelerators using high-charge-state ions produced by an intense, short pulse laser, and compares the costs of a modular driver system producing 6.5 MJ for a variety of ion masses and charge states using a simple but consistent cost model.
Date: November 15, 1996
Creator: Logan, B. G.; Perry, M. D. & Caporaso, G. J.
System: The UNT Digital Library
Ion beam synthesis and optical properties of semiconductor nanocrystals and quantum dots (open access)

Ion beam synthesis and optical properties of semiconductor nanocrystals and quantum dots

Nanocrystals of semiconductor materials have been fabricated in SiO{sub 2} by ion implantation and subsequent thermal annealing. Strong red photoluminescence (PL) peaked around 750 nm has been observed in samples containing Si nanocrystals in SiO{sub 2}. The Si nanocrystals in the samples with optimized PL intensities are a few nanometers in diameter. Difference in the absorption bandgap energies and the PL peak energies are discussed. Significant influence of implantation sequence on the formation of compound semiconductor nanocrystals are demonstrated with the GaAs in the SiO{sub 2} system. Optical absorption measurements show that Ga particles have already formed in the as-implanted stage if Ga is implanted first. A single surface phonon mode has been observed in the infrared reflectance measurement from samples containing GaAs nanocrystals.
Date: November 1, 1996
Creator: Zhu, J. G.; White, C. W. & Withrow, S. P.
System: The UNT Digital Library
Search for new mechanism of CP violation through decay of leptons and semileptonic decay of hadrons (open access)

Search for new mechanism of CP violation through decay of leptons and semileptonic decay of hadrons

If CP is violated in any decay process involving leptons it will signify the existence of a new scalar boson (called the X boson) responsible for CP violation that may be the key to understanding matter-antimatter asymmetry in the universe. The authors discuss the signatures of CP violation in (1) the decay of tau and mu leptons, and (2) the semileptonic decay of {pi}, K, D, B and t particles by measuring the polarization of the charged lepton in the decay. The authors discuss how the coupling constants and their phases of the coupling of the X boson to 9 quark vertices and 3 lepton vertices can be obtained through 12 decay processes.
Date: November 1, 1996
Creator: Tsai, Y. S.
System: The UNT Digital Library
137Cs(90Sr) and Pu isotopes in the Pacific Ocean sources & trends (open access)

137Cs(90Sr) and Pu isotopes in the Pacific Ocean sources & trends

The main source of artificial radioactivity in the world`s oceans can be attributed to worldwide fallout from atmospheric nuclear weapons testing. Measurements of selected artificial radionuclides in the Pacific Ocean were first conducted in the 1960`s where it was observed that fallout radioactivity had penetrated the deep ocean. Extensive studies carried out during the 1973-74 GEOSECS provided the first comprehensive data on the lateral and vertical distributions of {sup 9O}Sr, {sup 137}Cs and Pu isotopes in the Pacific on a basin wide scale. Estimates of radionuclide inventories in excess of amounts predicted to be delivered by global fallout alone were attributed to close-in fallout and tropospheric inputs from early U.S. tests conducted on Bikini and Enewetak Atolls in the Equatorial Pacific. In general, levels of fallout radionuclides (including {sup 9O}Sr, {sup 137}Cs and Pu isotopes) in the surface waters of the Pacific Ocean have decreased considerably over the past 4 decades and are now much more homogeneously distributed. Resuspension and the subsequent deposition of fallout radionuclides from previously deposited debris on land has become an important source term for the surface ocean. This can be clearly seen in measurements of fallout radionuclides in mineral aerosols over the Korean Peninsula (Yellow …
Date: November 1, 1996
Creator: Hamilton, T.F., Millies-Lacrox, J.C. & Hong, G.H.
System: The UNT Digital Library
Flashlamp for NIF: Russian variant (open access)

Flashlamp for NIF: Russian variant

A variant of the flashlamp for NIF was developed on the base of the experience of manufacture and application of high-power flashlamps in Russia. Features of flashlamp design as well as first test results of the experimental samples are presented.
Date: November 1, 1996
Creator: Erlandson, A.C.; Nikiforov, V.G.; Nikolaevskii, V.G.; Gerasimov, V.A. & Zapata, L.E.
System: The UNT Digital Library