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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
TOOKUIL: A case study in user interface development for safety code application (open access)

TOOKUIL: A case study in user interface development for safety code application

Traditionally, there has been a very high learning curve associated with using nuclear power plant (NPP) analysis codes. Even for seasoned plant analysts and engineers, the process of building or modifying an input model for present day NPP analysis codes is tedious, error prone, and time consuming. Current cost constraints and performance demands place an additional burden on today`s safety analysis community. Advances in graphical user interface (GUI) technology have been applied to obtain significant productivity and quality assurance improvements for the Transient Reactor Analysis Code (TRAC) input model development. KAPL Inc. has developed an X Windows-based graphical user interface named TOOKUIL which supports the design and analysis process, acting as a preprocessor, runtime editor, help system, and post processor for TRAC. This paper summarizes the objectives of the project, the GUI development process and experiences, and the resulting end product, TOOKUIL.
Date: November 1, 1996
Creator: Gray, D. L.; Harkins, C. K.; Hoole, J. G.; Peebles, R. C. & Smith, R. J.
System: The UNT Digital Library
Top mass measurements at CDF (open access)

Top mass measurements at CDF

We report on measurements of the top quark mass by the CDF experiment at the FermiLab Tevatron collider. The top quark is produced in {ital p{anti p}} collisions at {radical}{ital s} = 1.8 TeV. The analyses use an integrated luminosity of 110 pb{sup -1}. Results are presented from three decay channels, (i) one lepton plus jets, (ii) dilepton, (iii) all hadronic. The smallest error on the mass comes from (i), with a preliminary top mass value of 175.6 {+-}4.4 (stat.) {+-} 4.8 (syst.) GeV. Results from the other channels are consistent with this value.
Date: November 1, 1996
Creator: Lys, J.
System: The UNT Digital Library
Top quark study in all-jets channel at D0 (open access)

Top quark study in all-jets channel at D0

We report on the search for top quark decays into all-jets at the Tevatron collider. We measure preliminary cross sections of 4.4 {+-} 4.9 pb and 3.9 {+-} 9.8 pb for {ital t}{ital {anti t}} production, using singly and doubly {ital b}-tagged all-jets channels, respectively.
Date: November 1, 1996
Creator: Won, E.
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
Towards assessing the violence of reaction during cookoff of confined energetic materials (open access)

Towards assessing the violence of reaction during cookoff of confined energetic materials

An analysis of post-ignition events in a variable confinement cookoff test (VCCT) geometry is presented aimed toward predicting the level of violence during cookoff of confined thermally-degraded energetic materials. This study focuses on the dynamic events following thermal initiation whereby accelerated combustion interacts with confinement. Numerical simulations, based on a model of reactive multiphase mixtures, indicate that the response of energetic material is highly dependent upon thermal/mechanical damage states prior to ignition. These damaged states affect the rate of pressurization, dynamic compaction behavior and subsequent growth to detonation. Variations of the specific surface area and porosity produced by decomposition of the energetic material causes different responses ranging from pressure burst to detonation. Calculated stress histories are used in estimating breakup of the VCCT confinement based on Grady-Kipp fragmentation theory.
Date: November 1, 1996
Creator: Baer, M. R.; Kipp, M. E.; Schmitt, R. G. & Hobbs, M. L.
System: The UNT Digital Library
TRACE 3-D code improvements (open access)

TRACE 3-D code improvements

TRACE 3-D is an interactive beam-transport code for bunched beams that includes accelerating elements and linear space-charge forces. It has been integrated with an improved GUI (graphic user interface) based on the Shell for Particle Accelerator Related Codes. Recent modifications to the code include centroid tracking and an improved beam description consisting of a set of beam slices, each having its own 6D centroid and sigma matrix. This allows one to study some nonlinear effects, such as wakefields, that are related to the variation of the beam bunch along the longitudinal direction.
Date: November 1, 1996
Creator: Lysenko, W. P.; Rusthoi, D. P.; Chan, K. C. D.; Gillespie, G. H. & Hill, B. W.
System: The UNT Digital Library
A tracking code for injection and acceleration studies in synchrotrons (open access)

A tracking code for injection and acceleration studies in synchrotrons

CAPTURE-SPC is a Monte-Carlo-based tracking program that simulates the injection and acceleration processes in proton synchrotrons. The time evolution of a distribution of charged particles is implemented by a symplectic, second-order-accurate integration algorithm. The recurrence relations follow a time-stepping leap--frog method. The time-step can be varied optionally to reduce computer time. Space-charge forces are calculated by binning the phase-projected particle distribution. The statistical fluctuations introduced by the binning process are reduced by presmoothing the data by the cloud-in-cell method and by filtering. Both the bin size and amount of filtering can be varied during the acceleration cycle so that the bunch fine structure is retained while the short wavelength noise is attenuated. The initial coordinates of each macro particle together with its time of injection are retained throughout the calculations. This information is useful in determining low-loss injection schemes.
Date: November 1, 1996
Creator: Lessner, E. & Symon, K.
System: The UNT Digital Library
Transversely isotropic poroelasticity arising from thin isotropic layers (open access)

Transversely isotropic poroelasticity arising from thin isotropic layers

Percolation phenomena play central roles in the field of poroelasticity, where two distinct sets of percolating continua intertwine. A connected solid frame forms the basis of the elastic behavior of a poroelastic medium in the presence of confining forces, while connected pores permit a percolating fluid (if present) to influence the mechanical response of the system from within. The present paper discusses isotropic and anisotropic poroelastic media and establishes general formulas for the behavior of transversely isotropic poroelasticity arising from laminations of isotropic components. The Backus averaging method is shown to provide elementary means of constructing general formulas. The results for confined fluids are then compared with the more general Gassmann formulas that must be satisfied by any anisotropic poroelastic medium and found to be in complete agreement.
Date: November 1, 1996
Creator: Berryman, J.G.
System: The UNT Digital Library
Treatment of anisotropic damage development within a scalar damage formulation (open access)

Treatment of anisotropic damage development within a scalar damage formulation

This paper is concerned with describing a damage mechanics formulation which provides for non-isotropic effects using a scalar damage variable. An investigation has been in progress for establishing the constitutive behavior of rock salt at long times and low to moderate confining pressures in relation to the possible use of excavated rooms in rock salt formations as repositories for nuclear waste. An important consideration is the effect of damage manifested principally by the formation of shear induced wing cracks which have a stress dependent orientation. The analytical formulation utilizes a scalar damage parameter, but is capable of indicating the non- isotropic dependence of inelastic straining on the stress state and the confining pressure. Also, the equations indicate the possibility of volumetric expansions leading to the onset of tertiary creep and eventually rupture if the damage variable reaches a critical value.
Date: November 1, 1996
Creator: Chan, K. S.; Bodner, S. R. & Munson, D. E.
System: The UNT Digital Library
Two-dimensional modeling of magnetically imploded liners (open access)

Two-dimensional modeling of magnetically imploded liners

Magnetically imploded massive cylindrical liner drivers have been studied in two-dimensions for low, intermediate and high energy pulsed power systems. The simulations have been carried out using a resistive Eulerian magnetohydrodynamics computational model which includes material strength, and models the interactions between the imploding liner and the electrode walls. The computations simulate the generation of perturbations and their subsequent growth during the implosion. At low energies a solid liner remains in the plastic regime, reaching an inner cylindrical target with velocities of a few mm per {mu}s. At higher energies (where one-dimensional models predict implosion velocities of order 1 cm/{mu}s or more) resistive heating of the liner results in melting, and the effects of magnetically driven instabilities become important. We discuss the two-dimensional issues which arise in these systems. These include: the onset of perturbations associated with the motion of the liner along the electrodes; the growth of instabilities in liquid layers; and the suppression of instability growth during the implosion by maintaining a solid inner layer. Studies have been made of liners designed for the Pegasus capacitor bank facility (currents in the 5 - 12 MA regime), and for the Procyon high explosive system (currents in the 20 MA …
Date: November 1, 1996
Creator: Atchison, W. L.; Bowers, R. L.; Brownell, J. H. & Lee, H.
System: The UNT Digital Library
Use of historical trending in the validation of hazardous waste site monitoring data (open access)

Use of historical trending in the validation of hazardous waste site monitoring data

The Savannah River Site is a large nuclear weapons facility with over 2500 monitoring wells with an annual load of over 300,000 samples. Data are verified and validated using a program that performs routine data format checks as well as a statistical check on whether results fall within the expected range based on a trend of previous values. For analytical data, a linear fit of the previous eight sampling events is calculated along with a predicted value and confidence interval. If the result is outside the confidence interval for a linear fit, then a quadratic fit is attempted and any value outside of the quadratic fit confidence interval is flagged as an anomaly. The algorithm takes into account 90th percentile detection limits and dilution factors. When there is not enough data on a well to predict a trend, the algorithm uses data from all wells that are in same well group. Use of this historical trending algorithm has provided tremendous improvement over the previous method of performing the historical check. False anomaly indications have been reduced by roughly 60 percent.
Date: November 1, 1996
Creator: Aull, J.E. & Weber, J.H.
System: The UNT Digital Library
VSHOT: a tool for characterizing large, imprecise reflectors (open access)

VSHOT: a tool for characterizing large, imprecise reflectors

A prototype Video Scanning Hartmann Optical Tester (VSHOT) has been developed to characterize the optics of dish-type solar concentrators. VSHOT is a flexible platform that may characterize any large reflector with a focal length over diameter ratio (f{number_sign}) greater than 0. 45, and RMS optical error in the 0. I - I 0 milliradian range. The VSHOT hardware, software, and operation are described. Measurement uncertainty and preliminary test results are discussed. Another potential application being explored for the VSHOT is the quality assurance of slumped-glass automobile windshields. Preliminary test results from a reference optic and a section of a windshield are presented.
Date: November 1, 1996
Creator: Jones, S. A.; Neal, D. R.; Gruetzner, J. K.; Houser, R. M.; Edgar, R. M. & Wendelin, T. J.
System: The UNT Digital Library
W and Z production cross sections at D0 (open access)

W and Z production cross sections at D0

We present a measurement of the production cross section times branching ratio for {ital W} and {ital Z} bosons decaying to the electrons or muons in {ital p}{ital {anti p}} collisions at {radical}s = 1.8 TeV using data recorded at the Tevatron during the 1994-1995 collider run. Using the ratio of these two measurements, we derive the {ital W} leptonic branching fraction and the width of the {ital W} boson.
Date: November 1, 1996
Creator: Tarazi, J.N.
System: The UNT Digital Library
Weld overlay cladding with iron aluminides (open access)

Weld overlay cladding with iron aluminides

The hot and cold cracking tendencies of some early iron aluminide alloy compositions limited their use to applications where good weldability was not required. Considerable progress has been made toward improving this situation. Using hot crack testing techniques developed at ORNL and a systematic study of alloy compositional effects, we have established a range of compositions within which hot cracking resistance is very good, essentially equivalent to stainless steel. Cold cracking, however, remains an issue, and extensive efforts are continuing to optimize composition and welding parameters, especially preheat and postweld heat treatment, to minimize its occurrence. In terms of filler metal and process development, we have progressed from sheared strip through aspiration cast rod and shielded metal arc electrodes to the point where we can now produce composite wire with a steel sheath and aluminum core in coil form, which permits the use of both the gas tungsten arc and gas metal arc processes. This is a significant advancement in that the gas metal arc process lends itself well to automated welding, and is the process of choice for commercial weld overlay applications. Using the newly developed filler metals, we have prepared clad specimens for testing in a variety of …
Date: November 1, 1996
Creator: Goodwin, G. M.
System: The UNT Digital Library
Wide area continuous offender monitoring (open access)

Wide area continuous offender monitoring

The corrections system in the U.S. is supervising over five million offenders. This number is rising fast and so are the direct and indirect costs to society. To improve supervision and reduce the cost of parole and probation, first generation home arrest systems were introduced in 1987. While these systems proved to be helpful to the corrections system, their scope is rather limited because they only cover an offender at a single location and provide only a partial time coverage. To correct the limitations of first-generation systems, second-generation wide area continuous electronic offender monitoring systems, designed to monitor the offender at all times and locations, are now on the drawing board. These systems use radio frequency location technology to track the position of offenders. The challenge for this technology is the development of reliable personal locator devices that are small, lightweight, with long operational battery life, and indoors/outdoors accuracy of 100 meters or less. At the center of a second-generation system is a database that specifies the offender`s home, workplace, commute, and time the offender should be found in each. The database could also define areas from which the offender is excluded. To test compliance, the system would compare the …
Date: November 1, 1996
Creator: Hoshen, J.; Drake, G. & Spencer, D.
System: The UNT Digital Library
Yrast excitations around {sup 132}Sn: The two and three valence- proton N = 82 isotones {sup 134}Te and {sup 135}I (open access)

Yrast excitations around {sup 132}Sn: The two and three valence- proton N = 82 isotones {sup 134}Te and {sup 135}I

Large multidetector {gamma}-ray arrays, which can separate the prompt {gamma}-ray cascades within a single fission product nucleus (of moderate yield) from the bulk of prompt {gamma}-rays, has now opened new prospects for studies of yrast excitations in {sup 132}Sn and the few valence particle nuclei around it. Measurements were performed at Eurogam II using a {sup 248}Cm source. This paper features the results for the two and three valence proton N=82 isotones {sup 134}Te and {sup 135}I which exhibit simple clearcut excitation modes, resembling {sup 210}Po and {sup 211}At, their well studied N=126 counterparts in the {sup 208}Pb region. A search was made for new {sup 135}I transitions by setting a single coincidence gate on 1134 keV {gamma}-rays; strong 288, 572, 690, 725, 1661, 1695, and 2247 keV coincident {gamma}-rays were identified as {sup 135}I {gamma}-rays. In summary, yrast excitations to above 5.5 MeV excitation energy in the 2- and 3-proton nuclei {sup 134}Te and {sup 135}I have been established and interpreted with help of shell model calculations using empirical nucleon-nucleon interactions. This opens possibilities for exploring simple excitation modes in the {sup 132}Sn region under conditions comparable with but not identical to those in the well-studied {sup 208}Pb region.
Date: November 1996
Creator: Daly, P. J.; Zhang, C. T. & Bhattacharyya, P.
System: The UNT Digital Library
D-Zero muon readout electronics design (open access)

D-Zero muon readout electronics design

The readout electronics designed for the D{null} Muon Upgrade are described. These electronics serve three detector subsystems and one trigger system. The front-ends and readout hardware are synchronized by means of timing signals broadcast from the D{null} Trigger Framework. The front-end electronics have continuously running digitizers and two levels of buffering resulting in nearly deadtimeless operation. The raw data is corrected and formatted by 16- bit fixed point DSP processors. These processors also perform control of the data buffering. The data transfer from the front-end electronics located on the detector platform is performed by serial links running at 160 Mbit/s. The design and test results of the subsystem readout electronics and system interface are discussed.
Date: November 1, 1996
Creator: Baldin, B.; Hansen, S.; Los, S.; Matveev, M. & Vaniev, V.
System: The UNT Digital Library
Zlib: A numerical library for optimal design of truncated power series algebra and map parameterization routines (open access)

Zlib: A numerical library for optimal design of truncated power series algebra and map parameterization routines

A brief review of the Zlib development is given. Emphasized is the Zlib nerve system which uses the One-Step Index Pointers (OSIPs) for efficient computation and flexible use of the Truncated Power Series Algebra (TPSA). Also emphasized is the treatment of parameterized maps with an object-oriented language (e.g. C++). A parameterized map can be a Vector Power Series (Vps) or a Lie generator represented by an exponent of a Truncated Power Series (Tps) of which each coefficient is an object of truncated power series.
Date: November 1, 1996
Creator: Yan, Y.T.
System: The UNT Digital Library