CP Violation in B Decays at the Tevatron (open access)

CP Violation in B Decays at the Tevatron

Between 1992 to 1996, the CDF and D0 detectors each collected data samples exceeding 100 pb{sup {minus}1} of p{bar p} collisions at {radical}s = 1.8 TeV at the Fermilab Tevatron. These data sets led to a large number of precision measurements of the properties of B hadrons including lifetimes, masses, neutral B meson flavor oscillations, and relative branching fractions, and to the discovery of the B{sub 0} meson. Perhaps the most exciting result was the first look at the CP violation parameter sin ({vert_bar}2{beta}){vert_bar} using the world's largest sample of fully reconstructed B{sup 0}/{bar B}{sup 0} {r_arrow} J/{psi}K{sub s}{sup 0} decays. A summary of this result is presented here. In the year 2000, the Tevatron will recommence p{bar p} collisions with an over order of magnitude expected increased in integrated luminosity (1 fb{sup {minus}1} per year). The CDF and D0 detectors will have undergone substantial upgrades, particularly in the tracking detectors and the triggers. With these enhancements, the Tevatron B physics program includes precision measurements of sin(2{beta}) and B{sub s}{sup 0} flavor oscillations, as well as studies of rare B decays that are sensitive to new physics. The studies of B{sub s}{sup 0} mesons will be particularly interesting as this …
Date: September 17, 1999
Creator: Kroll, I. Joseph
System: The UNT Digital Library
Neutron spectroscopy of high-density amorphous ice. (open access)

Neutron spectroscopy of high-density amorphous ice.

Vibrational spectra of high-density amorphous ice (hda-ice) for H{sub 2}O and D{sub 2}O samples were measured by inelastic neutron scattering. The measured spectra of hda-ice are closer to those for high-pressure phase ice-VI, but not for low-density ice-Ih. This result suggests that similar to ice-VI the structure of hda-ice should consist of two interpenetrating hydrogen-bonded networks having no hydrogen bonds between themselves.
Date: July 17, 1998
Creator: Kolesnikov, A. I.
System: The UNT Digital Library
Validating the role of AFVs in voluntary mobile source emission reduction programs. (open access)

Validating the role of AFVs in voluntary mobile source emission reduction programs.

Late in 1997, EPA announced new allowances for voluntary emission control programs. As a result, the US Department of Energy's (DOE) Clean Cities and other metro areas that have made an ongoing commitment to increasing participation by alternative fuel vehicles (AFVs) in local fleets have the opportunity to estimate the magnitude and obtain emission reduction credit for following through on that commitment. Unexpectedly large reductions in key ozone precursor emissions in key locations and times of the day can be achieved per vehicle-mile by selecting specific light duty AFV offerings from original equipment manufacturers (OEMs) in lieu of their gasoline-fueled counterparts. Additional benefit accrues from the fact that evaporative emissions of non-methane hydrocarbons (generated in the case of CNG, LNG, and LPG by closed fuel-system AFV technology) can be essentially negligible. Upstream emissions from fuel storage and distribution with the airshed of interest are also reduced. This paper provides a justification and outlines a method for including AFVs in the mix of strategies to achieve local and regional improvements in ozone air quality, and for quantifying emission reduction credits. At the time of submission of this paper, the method was still under review by the US EPA Office of Mobile …
Date: March 17, 1999
Creator: Santini, D. J. & Saricks, C. L.
System: The UNT Digital Library
Examination of subaerially altered basaltic glass with TEM and EELS (open access)

Examination of subaerially altered basaltic glass with TEM and EELS

We have examined the weathered surfaces of 720 year old Hawaiian basalt glasses that were recovered from a subaerial environment with high-resolution transmission electron microscopy (TEM) and energy filtered imaging and electron energy loss spectroscopy (EELS) techniques. Whereas the alteration products (palagonite) were physically detached from the underlying glass in most samples, a gel-like amorphous layer was observed adjacent to the glass in a few samples. To our knowledge, this is the first time a gel layer has been observed on weathered basalt. This is significant because analogous gel layers have been observed on nuclear waste glasses reacted in laboratory tests, and this demonstrates an important similarity in the mechanisms of the weathering of basalt and the corrosion of waste glasses.
Date: June 17, 1998
Creator: Luo, J. S. & Ebert, W. L.
System: The UNT Digital Library
The performance of the small-angle diffractometer, SAND at IPNS. (open access)

The performance of the small-angle diffractometer, SAND at IPNS.

The time-of-flight small-angle diffractometer SAND has been serving the scientific user community since 1996. One notable feature of SAND is its capability to measure the scattered intensity in a wide Q (4{pi}sin{theta}/{lambda}, where 2{theta} is the scattering angle and {lambda} is the wavelength of the neutrons) range of 0.0035 to 0.5 {angstrom}{sup {minus}1} in a single measurement. The optical alignment system makes it easy to set up the instrument and the sample. The cryogenically cooled MgO filter reduces the fast neutrons over two orders of magnitude, while still transmitting over 70% of the cold neutrons. A drum chopper running at 15 Hz suppresses the delayed neutron background. SAND has a variety of ancillary equipment to control the sample environment. In this paper we describe the features of the SAND instrument, compare its data on a few standard samples with those measured at well established centers in the world, and display two scientific examples which take advantage of measuring data in a wide Q-range in a single measurement. With a new set of tight collimators the Q{sub min} can be lowered to 0.002 {angstrom}{sup {minus}1} and the presently installed high-angle bank of detectors will extend the Q{sub max} to 2 {angstrom}{sup …
Date: July 17, 1998
Creator: Thiyagarajan, P.
System: The UNT Digital Library
Thermal management in inertial fusion energy slab amplifiers (open access)

Thermal management in inertial fusion energy slab amplifiers

As the technology associated with the development of solid-state drivers for inertial fusion energy (IFE) has evolved, increased emphasis has been placed on the development of an efficient approach for managing the waste heat generated in the laser media. This paper addresses the technical issues associated with the gas cooling of large aperture slabs, where the laser beam propagates through the cooling fluid. It is shown that the major consequence of proper thermal management is the introduction of simple wedge, or beam steering, into the system. Achieving proper thermal management requires careful consideration of the geometry, cooling fluid characteristics, cooling flow characteristics, as well as the thermal/mechanical/optical characteristics of the laser media. Particularly important are the effects of cooling rate variation and turbulent scattering on the system optical performance. Helium is shown to have an overwhelming advantage with respect to turbulent scattering losses. To mitigate cooling rate variations, the authors introduce the concept of flow conditioning. Finally, optical path length variations across the aperture are calculated. A comparison of two laser materials (S-FAP and YAG) shows the benefit of a nearly a-thermal material on optical variations in the system.
Date: July 17, 1995
Creator: Sutton, S. B. & Albrecht, G. F.
System: The UNT Digital Library
Stress Voiding in IC Interconnects - Rules of Evidence for Failure Analysts (open access)

Stress Voiding in IC Interconnects - Rules of Evidence for Failure Analysts

Mention the words ''stress voiding'', and everyone from technology engineer to manager to customer is likely to cringe. This IC failure mechanism elicits fear because it is insidious, capricious, and difficult to identify and arrest. There are reasons to believe that a damascene-copper future might be void-free. Nevertheless, engineers who continue to produce ICs with Al-alloy interconnects, or who assess the reliability of legacy ICs with long service life, need up-to-date insights and techniques to deal with stress voiding problems. Stress voiding need not be fearful. Not always predictable, neither is it inevitable. On the contrary, stress voids are caused by specific, avoidable processing errors. Analytical work, though often painful, can identify these errors when stress voiding occurs, and vigilance in monitoring the improved process can keep it from recurring. In this article, they show that a methodical, forensics approach to failure analysis can solve suspected cases of stress voiding. This approach uses new techniques, and patiently applies familiar ones, to develop evidence meeting strict standards of proof.
Date: September 17, 1999
Creator: FILTER, WILLIAM F.
System: The UNT Digital Library
Decay heat removal by natural convection - the RVACS system. (open access)

Decay heat removal by natural convection - the RVACS system.

In conclusion, this work shows that for sodium coolant the reactor vessel auxiliary cooling system (RVACS) is an effective passive heat removal system if the reactor power does not exceed about 1600 MW(th). Its effectiveness is limited by the effective radiative heat transfer coefficient in the inner gap. In a lead cooled system, economic considerations may impose a lower limit.
Date: August 17, 1999
Creator: Tzanos, C. P.
System: The UNT Digital Library
Terascale spectral element algorithms and implementations. (open access)

Terascale spectral element algorithms and implementations.

We describe the development and implementation of an efficient spectral element code for multimillion gridpoint simulations of incompressible flows in general two- and three-dimensional domains. We review basic and recently developed algorithmic underpinnings that have resulted in good parallel and vector performance on a broad range of architectures, including the terascale computing systems now coming online at the DOE labs. Sustained performance of 219 GFLOPS has been recently achieved on 2048 nodes of the Intel ASCI-Red machine at Sandia.
Date: August 17, 1999
Creator: Fischer, P. F. & Tufo, H. M.
System: The UNT Digital Library
What's in your bookmark? Green building information on the Web. (open access)

What's in your bookmark? Green building information on the Web.

In listing web sites that are of special interest to the Affordable Comfort community, we will try to categorize sites in six major areas: Green Building Product Directories, Software Tools on the Web, Good Places for Learning, Health and Indoor Environment Information, Important Discussion Groups and E-mail Lists, and Sites of Sites. Since we can not help but leave out a great deal, we invite the reader to contact us for lists of sites that we could not include.
Date: February 17, 1999
Creator: Cavallo, J. D. & Iversen, M. R.
System: The UNT Digital Library
Lessons learned from applying VIM to fast reactor critical experiments (open access)

Lessons learned from applying VIM to fast reactor critical experiments

VIM is a continuous energy Monte Carlo code first developed around 1970 for the analysis of plate-type, fast-neutron, zero-power critical assemblies. In most respects, VIM is functionally equivalent to the MCNP code but it has two features that make uniquely suited to the analysis of fast reactor critical experiments: (1) the plate lattice geometry option, which allows efficient description of and neutron tracking in the assembly geometry, and (2) a statistical treatment of neutron cross section data in the unresolved resonance range. Since its inception, VIM`s capabilities have expanded to include numerous features, such as thermal neutron cross sections, photon cross sections, and combinatorial and other geometry options, that have allowed its use in a wide range of neutral-particle transport problems. The earliest validation work at Argonne National Laboratory (ANL) focused on the validation of VIM itself. This work showed that, in order for VIM to be a ``rigorous`` tool, extreme detail in the pointwise Monte Carlo libraries was needed, and the required detail was added. The emphasis soon shifted to validating models, methods, data and codes against VIM. Most of this work was done in the context of analyzing critical experiments in zero power reactor (ZPR) assemblies. The purpose …
Date: May 17, 1995
Creator: Schaefer, R.W.; McKnight, R.D. & Collins, P.J.
System: The UNT Digital Library
Phase stability and grain growth in an Ag/Bi-2223 composite conductor prepared using fine-grained Bi-2223 as a precursor. (open access)

Phase stability and grain growth in an Ag/Bi-2223 composite conductor prepared using fine-grained Bi-2223 as a precursor.

We have investigated the stability and microstructural transformability of the Bi-2223 phase in a silver-sheathed monofilament composite tape fabricated using fine-grained Bi{sub 1.7}Pb{sub 0.3}Sr{sub 1.9}Ca{sub 2.0}-Cu{sub 3.0}O{sub y} (Bi-2223) as the precursor powder. The fully formed Bi-2223 precursor was prepared using established procedures. The purpose of this study was to explore the prospects for growing textured, large-grain-size Bi-2223 from the fine-grained precursor by process parameter perturbations. These perturbations included thermal ramp up variations, programmed heat treatment temperature and oxygen pressure fluctuations, and parameter manipulations during cool-down. Our results show that the types of heat treatments used in conventional oxide-powder-in-tube (OPIT) processing do not facilitate Bi-2223 grain growth when the precursor powder is preconcerted Bi-2223. We also observed that the Bi-2223 partially. decomposed during conventional thermal ramp-up in 0.075 atm O{sub 2}, but that this decomposition can be inhibited by ramping up in a reduced oxygen pressure. A pathway was found for back-reacting the fine-grained Bi-2223 (to Bi-2212, Bi-2201 and nonsuperconducting secondary phases), then reforming large-grained Bi-2223 in a colony microstructure having some distinct differences from that produced during conventional OPIT processing.
Date: September 17, 1998
Creator: Merchant, N. N.
System: The UNT Digital Library
Fluoro-Carbonate Solvents for Li-Ion Cells (open access)

Fluoro-Carbonate Solvents for Li-Ion Cells

A number of fluoro-carbonate solvents were evaluated as electrolytes for Li-ion cells. These solvents are fluorine analogs of the conventional electrolyte solvents such as dimethyl carbonate, ethylene carbonate, diethyl carbonate in Li-ion cells. Conductivity of single and mixed fluoro carbonate electrolytes containing 1 M LiPF{sub 6} was measured at different temperatures. These electrolytes did not freeze at -40 C. We are evaluating currently, the irreversible 1st cycle capacity loss in carbon anode in these electrolytes and the capacity loss will be compared to that in the conventional electrolytes. Voltage stability windows of the electrolytes were measured at room temperature and compared with that of the conventional electrolytes. The fluoro-carbon electrolytes appear to be more stable than the conventional electrolytes near Li voltage. Few preliminary electrochemical data of the fluoro-carbonate solvents in full cells are reported in the literature. For example, some of the fluorocarbonate solvents appear to have a wider voltage window than the conventional electrolyte solvents. For example, methyl 2,2,2 trifluoro ethyl carbonate containing 1 M LiPF{sub 6} electrolyte has a decomposition voltage exceeding 6 V vs. Li compared to <5 V for conventional electrolytes. The solvent also appears to be stable in contact with lithium at room temperature.
Date: September 17, 1999
Creator: Nagasubramanian, Ganesan
System: The UNT Digital Library
Measuring explosive non-ideality (open access)

Measuring explosive non-ideality

The sonic reaction zone length may be measured by four methods: (1) size effect, (2) detonation front curvature, (3) crystal interface velocity and (4) in-situ gauges. The amount of data decreases exponentially from (1) to (4) with there being almost no gauge data for prompt detonation at steady state. The ease and clarity of obtaining the reaction zone length increases from (1) to (4). The method of getting the reaction zone length, <x{sub e}>, is described for the four methods. A measure of non-ideality is proposed: the reaction zone length divided by the cylinder radius. N = <x{sub e}>/R{sub o}. N = 0 for true ideality. It also decreases with increasing radius as it should. For N < 0.10, an equilibrium EOS like the JWL may be used. For N > 0.10, a time-dependent description is essential. The crystal experiment, which measures the particle velocity of an explosive-transparent material interface, is presently rising in importance. We examine the data from three experiments and apply: (1) an impedance correction that transfers the explosive C-J particle velocity to the corresponding value for the interface, and (2) multiplies the interface time by 3/4 to simulate the explosive speed of sound. The result is …
Date: February 17, 1999
Creator: Souers, P C
System: The UNT Digital Library
Transient analysis of a flywheel battery containment during a full rotor burst event. (open access)

Transient analysis of a flywheel battery containment during a full rotor burst event.

Flywheels are being developed for use in an Advanced Locomotive Propulsion System (ALPS) targeted for use in high speed passenger rail service. The ALPS combines high performance, high speed gas turbines, motor/generators and flywheels to provide a light-weight, fuel-efficient power system. Such a system is necessary to avoid the high cost of railway electrification, as is currently done for high speed rail service (>100mph) since diesels are too heavy. The light-weight flywheel rotors are made from multilayered composite materials, and are operated at extremely high energy levels. Metal containment structures have been designed to enclose the rotors and provide encapsulation of the rotor during postulated failure events. One such event is a burst mode failure of the rotor in which the composite rim is assumed to burst into debris that impacts against the containment. This paper presents a finite element simulation of the transient structural response of a subscale metal flywheel containment structure to a rotor burst event.
Date: April 17, 1998
Creator: Hsieh, B. J.
System: The UNT Digital Library
Structure and formation mechanism of the transfermium isotope {sup 254}No. (open access)

Structure and formation mechanism of the transfermium isotope {sup 254}No.

The ground-state band of the Z=102 isotope {sup 254}No has been identified up to spin 14, indicating that the nucleus is deformed. The deduced quadruple deformation, {beta} = 0.27, is in agreement with theoretical predictions. These observations confirm that the shell-correction energy responsible for the stability of transfermium nuclei is partly derived from deformation. The survival of {sup 254}No up to spin 14 means that its fission barrier persists at least up to that spin.
Date: December 17, 1998
Creator: Reiter, P.
System: The UNT Digital Library
Thermal Stability of Li-Ion Cells (open access)

Thermal Stability of Li-Ion Cells

The thermal stability of Li-ion cells with intercalating carbon anodes and metal oxide cathodes was measured as a function of state of charge and temperature for two advanced cell chemistries. Cells of the 18650 design with Li{sub x}CoO{sub 2} cathodes (commercial SONY cells) and Li{sub x}Ni{sub 0.8}Co{sub 0.2}O{sub 2} cathodes were measured for thermal reactivity in the open circuit cell condition. Accelerating rate calorimetry (ARC) was used to measure cell thermal runaway as a function of state of charge (SOC). Microcalorimetry was used to measure the time dependence of heat generating side reactions also as a function of SOC. Components of cells were measured using differential scanning calorimetry (DSC) to study the thermal reactivity of the individual electrodes to determine the temperature regimes and conditions of the major thermal reactions. Thermal decomposition of the SEI layer at the anodes was identified as the initiating source for thermal runaway. The cells with Li{sub x}CoO{sub 2} cathodes showed greater sensitivity to SOC and higher accelerating heating rates than seen for the cells with Li{sub x}Ni{sub 0.8}Co{sub 0.2}O{sub 2}cathodes. Lower temperature reactions starting as low as 40 C were also observed that were SOC dependent but not accelerating. These reactions were also measured …
Date: September 17, 1999
Creator: ROTH,EMANUEL P.
System: The UNT Digital Library
Seismic studies of the San Francisco-Oakland Bay Bridge (open access)

Seismic studies of the San Francisco-Oakland Bay Bridge

Computational simulation plays a central role in the engineering analysis and design of major bridge structures and accurate simulations are essential for the development of earthquake resistant and economical structural designs. This paper describes new methodologies and computational tools which have recently been developed for simulating earthquake ground motions and the seismic response of cable supported bridges. The simulation tools are described and an example application for an important long-span suspension bridge is demonstrated. The application portion of the study has particular focus on the potential damaging effects of long period displacement pulses and permanent ground displacements which can occur when a bridge is located in the near-field of a major earthquake fault.
Date: August 17, 1999
Creator: Astaneh-Asl, A.; Larsen, S. & McCallen, D.
System: The UNT Digital Library
Three-dimensional modeling of a time-of-flight mass spectrometer : optimization of SNMS/SIMS transmission using Simion. (open access)

Three-dimensional modeling of a time-of-flight mass spectrometer : optimization of SNMS/SIMS transmission using Simion.

A computer program that models secondary ion and post-ionized neutral trajectories through the SARISA instrument has been developed. The program has been tested by determining the transmission of secondary ions for two different ion energies. Results indicate that the model accurately reflects the transmission of the SARISA instrument. The developed algorithm for creating ions and monitoring their parameters is generic and can be used for examining other SIMS/SNMS instruments and ion sources.
Date: August 17, 1999
Creator: Calaway, W. F.; Pellin, M. J. & Veryovkin, I. V.
System: The UNT Digital Library
Crystal phases, microstructure and surface chemistry of industry-relevant nanostructured metal oxides. (open access)

Crystal phases, microstructure and surface chemistry of industry-relevant nanostructured metal oxides.

Industries response keenly to two factors: the costs of materials and processing, and regulatory forces imposed by governments. The method of neutron scattering maybe applied to address these concerns. Slow (cold to epithermal) neutrons probe the organization and dynamic response of atomic nuclei and electrons in a substance thereby providing valuable knowledge toward the development of cost-effective means for materials preparation and possessing. Neutron facilities for basic research are funded by governments, thus these organizations are obliged to provide technical support to industries for the fulfillment of governmental policies. I hope to argue, based on these premises, the mutual beneficialness of a close collaboration between the industrial-research and neutron-scattering communities. In order to limit the scope of discussion, I shall illustrate the potential applications of neutron scattering for industrial problems by some recent studies of nanostructured metal-oxide catalysts.
Date: April 17, 1998
Creator: Loong, C.-K.
System: The UNT Digital Library
Collaborative virtual reality environments for computational science and design. (open access)

Collaborative virtual reality environments for computational science and design.

The authors are developing a networked, multi-user, virtual-reality-based collaborative environment coupled to one or more petaFLOPs computers, enabling the interactive simulation of 10{sup 9} atom systems. The purpose of this work is to explore the requirements for this coupling. Through the design, development, and testing of such systems, they hope to gain knowledge that allows computational scientists to discover and analyze their results more quickly and in a more intuitive manner.
Date: February 17, 1998
Creator: Papka, M. E.
System: The UNT Digital Library
Software for the parallel adaptive solution of conservation laws by discontinous Galerkin methods. (open access)

Software for the parallel adaptive solution of conservation laws by discontinous Galerkin methods.

The authors develop software tools for the solution of conservation laws using parallel adaptive discontinuous Galerkin methods. In particular, the Rensselaer Partition Model (RPM) provides parallel mesh structures within an adaptive framework to solve the Euler equations of compressible flow by a discontinuous Galerkin method (LOCO). Results are presented for a Rayleigh-Taylor flow instability for computations performed on 128 processors of an IBM SP computer. In addition to managing the distributed data and maintaining a load balance, RPM provides information about the parallel environment that can be used to tailor partitions to a specific computational environment.
Date: August 17, 1999
Creator: Flaherty, J. E.; Loy, R. M.; Shephard, M. S. & Teresco, J. D.
System: The UNT Digital Library
Bioremediation of Uranium Contaminated Soils and Wastes. (open access)

Bioremediation of Uranium Contaminated Soils and Wastes.

Contamination of soils, water, and sediments by radionuclides and toxic metals from uranium mill tailings, nuclear fuel manufacturing and nuclear weapons production is a major concern. Studies of the mechanisms of biotransformation of uranium and toxic metals under various microbial process conditions has resulted in the development of two treatment processes: (i) stabilization of uranium and toxic metals with reduction in waste volume and (ii) removal and recovery of uranium and toxic metals from wastes and contaminated soils. Stabilization of uranium and toxic metals in wastes is accomplished by exploiting the unique metabolic capabilities of the anaerobic bacterium, Clostridium sp. The radionuclides and toxic metals are solubilized by the bacteria directly by enzymatic reductive dissolution, or indirectly due to the production of organic acid metabolites. The radionuclides and toxic metals released into solution are immobilized by enzymatic reductive precipitation, biosorption and redistribution with stable mineral phases in the waste. Non-hazardous bulk components of the waste such as Ca, Fe, K, Mg and Na released into solution are removed, thus reducing the waste volume. In the second process uranium and toxic metals are removed from wastes or contaminated soils by extracting with the complexing agent citric acid. The citric-acid extract is …
Date: September 17, 1998
Creator: Francis, A. J.
System: The UNT Digital Library
The CDF silicon vertex tracker: Online precision tracking of the CDF silicon vertex detector (open access)

The CDF silicon vertex tracker: Online precision tracking of the CDF silicon vertex detector

The Silicon Vertex Tracker is the CDF online tracker which will re- construct 2D tracks using hit positions measured by the Silicon Vertex Detector and Central Outer Chamber tracks found by the eXtremely Fast Tracker. The precision measurement of the track impact parameter will allow triggering on events contain- ing B hadrons. This will allow the investigation of several important problems in B physics, like CP violation and B<sub>s</sub> mixing, and to search for new heavy particles decaying to b{anti b} .
Date: September 17, 1999
Creator: al., W. Ashmanskas et
System: The UNT Digital Library