Hadron supercolliders: The 1-TeV scale and beyond (open access)

Hadron supercolliders: The 1-TeV scale and beyond

Greater understanding of the connection between the weak and electromagnetic interactions is central to progress in elementary-particle physics. A definitive exploration of the mechanism for electroweak symmetry breaking will require collisions between fundamental constituents at energies on the order of 1 TeV. This goal drives the design of high-energy, high-luminosity hadron colliders that will be commissioned during the next decade, but by no means completely defines their scientific potential. These three lectures are devoted to a review of the standard-model issues that motivated an experimental assault on the 1-TeV scale, an introduction to the machines and the experimental environment they will present, and a survey of possibilities for measurement and discovery with a multi-TeV hadron collider. 72 refs., 29 figs.
Date: August 10, 1990
Creator: Quigg, C.
System: The UNT Digital Library
QCD studies at the hadron colliders (open access)

QCD studies at the hadron colliders

Two hadron collider experiments are actively pursuing QCD jet analyses. They are CDF, with a {radical}s = 1800 GeV, and UA2, with a {radical}s = 630 GeV. Recent results from these collaborations are discussed. The inclusive jet spectrum, dijet mass and angular distribution are compared to QCD predictions and used to set limits on quark substructure. Data from both experiments are compared to the O({alpha}{sub s}{sup 3}) calculations for the inclusive jet cross section. Studies of 3-jet, 4-jet and 5-jet events are described. A limit is set on the cross section for double parton scattering from the UA2 4-jet analysis. The inclusive photon cross section has been measured by both CDF and UA2 and is compared to theoretical predictions. 13 refs., 17 figs., 1 tab.
Date: August 10, 1990
Creator: Flaugher, B.L.
System: The UNT Digital Library
Numerical simulations of interfacial debonding in ductile-phase reinforced intermetallic matrix composites (open access)

Numerical simulations of interfacial debonding in ductile-phase reinforced intermetallic matrix composites

The fracture toughness of brittle intermetallic compounds can be improved by ductile-phase reinforcements. Effectiveness of the ductile phase in bridging cracks, and therefore increasing, the composite toughness, is known qualitatively to depend upon the extent of debonding, between the two phases. Numerical crack-growth simulations are used here to provide semi-quantitative predictions of the influence of interfacial debonding on the macroscopic stress-displacement behavior and, hence, the fracture toughness of an idealized Pb/glass composite. The interfacial toughness required to cause debonding, characterized by a constant critical energy release rate, is varied parametrically. As expected, higher interfacial toughness results in less interphase debonding, higher composite strength, and greater ductile-phase constraint. Consequently, the increase in ductile-phase triaxiality can potentially accelerate internal void formation and growth or facilitate cleavage fracture, either of which would likely decrease the toughness of the composite.
Date: August 10, 1993
Creator: Henshall, G. A.; Zywicz, E. & Strum, M. J.
System: The UNT Digital Library
Commentary on ``Future directions: Building technologies and design tools`` (open access)

Commentary on ``Future directions: Building technologies and design tools``

This paper presents a number of interesting and thought-provoking scenarios about the future use of advanced technology in the design and operation of commercial buildings. I will express my reactions in the following series of short paragraphs. These thoughts will, I hope, raise some new questions and offer fruitful directions for further exploration.
Date: August 10, 1992
Creator: Quadrel, R. W.
System: The UNT Digital Library
Physical and chemical sensor technologies developed at Lawrence Livermore National Laboratory (open access)

Physical and chemical sensor technologies developed at Lawrence Livermore National Laboratory

The increasing emphasis on envirorunental issues, waste reduction, and improved efficiency for industrial processes has mandated the development of new chemical and physical sensors for field or in-plant use. The Lawrence Livermore National Laboratory (LLNL) has developed a number of technologies for sensing physical and chemical properties. Table 1 gives some examples of several sensors. that have been developed recently for environmental, industrial, commercial or government applications. Physical sensors of pressure, temperature, acceleration, acoustic vibration spectra, and ionizing radiation have been developed. Sensors developed at LLNL for chemical species include inorganic solvents, heavy metal ions`, and gaseous atoms and compounds. Primary sensing technologies we have employed have been based on optical fibers, semiconductor optical or radiation detectors, electrochemical activity, micromachined electromechanical (MEMs) structures, or chemical separation technologies. The complexities of these sensor systems range from single detectors to more advanced micro-instruments on-a-chip. For many of the sensors we have developed the necessary intelligent electronic support systems for both local and remote sensing applications. Each of these sensor technologies are briefly described in the remaining sections of this paper.
Date: August 10, 1993
Creator: Balch, J. W.; Ciarlo, D.; Folta, J.; Glass, R.; Hagans, K.; Milanovich, F. et al.
System: The UNT Digital Library
High Resolution Diagnostics of a Linear Shaped Charge Jet (open access)

High Resolution Diagnostics of a Linear Shaped Charge Jet

The linear shaped charge is designed to produce a knife blade-like flat jet, which will perforate and sever one side of a modestly hard target from the other. This charge is approximately plane wave initiated and used a water pipe quality circular copper liner. To establish the quality of this jet we report about an experiment using several of the Lawrence Livermore National Laboratory high-resolution diagnostics previously published in this meeting [1]. Image converter tube camera stereo image pairs were obtained early in the jet formation process. Individual IC images were taken just after the perforation of a thin steel plate. These pictures are augmented with 70 mm format rotating mirror framing images, orthogonal 450 KeV flash radiograph pairs, and arrival time switches (velocity traps) positioned along the length of the jet edge. We have confirmed that linear shaped charges are subject to the same need for high quality copper as any other metal jetting device.
Date: August 10, 1999
Creator: Chase, J. B.; Kuklo, R. M.; Shaw, L. L.; Carter, D. L. & Baum, D. W.
System: The UNT Digital Library
Copper Wetting of x-Al(2)O(3)(0001): Theory and Experiment (open access)

Copper Wetting of x-Al(2)O(3)(0001): Theory and Experiment

XPS studies have been carried out on sputter deposited copper on a substantially hydroxylated {alpha}-Al{sub 2}O{sub 3}(0001) (sapphire) surface under ultra-high vacuum (UHV) conditions. XPS-derived Cu uptake curves show a sharp change in slope at a coverage of 0.35 monolayer (on a Cu/O atomic basis), indicative of initial layer-by-layer growth. CU(LMM) lineshape data indicate that, prior to the first break in the curve, Cu is oxidized to Cu(I). At higher coverages, metallic CU(0) is. observed. These data agree with first principles theoretical calculations, indicating that the presence of ad-hydroxyl groups greatly enhances the binding of Cu to bulk sapphire surfaces, stabilizing Cu(I) adatoms over two-dimensional metallic islands. In the absence of hydroxylation, calculations indicate significantly weaker Cu binding to the bulk sapphire substrate and non-wetting. Calculations also predict that at Cu coverages above 1/3 monolayer (ML), Cu-Cu interactions predominate, leading to Cu(0) formation. These results are in excellent agreement with experiment. The ability of surface hydroxyl groups to enhance binding to alumina substrates suggests a reason for contradictory experimental results reported in the literature for Cu wetting of alumina.
Date: August 10, 1999
Creator: Bogicevic, A.; Jennison, D. R.; Kelber, J. A.; Niu, Chengyu & Shepherd, K.
System: The UNT Digital Library
Structure-Dependent Viscoelastic Properties of C(9)-Alkanethiol Monolayers (open access)

Structure-Dependent Viscoelastic Properties of C(9)-Alkanethiol Monolayers

Quartz crystal microbalance techniques and in situ spectroscopic ellipsometry are used to probe the structure-dependent intrinsic viscoelastic properties of self-assembled CH{sub 3}(CH{sub 2}){sub 8}SH alkanethiol monolayer adsorbed from the gas phase onto Au(111)-textured substrates. Physisorbed molecules, mixed chemisorbed-fluid/solid phases and solid-phase domain boundaries make sequentially dominant contributions to the measured energy dissipation in the growing monolayer. Deviations from Langmuir adsorption kinetics reveal a precursor-mediated adsorption channel. These studies reveal the impact of structural heterogeneity in tribological studies of monolayer lubricants.
Date: August 10, 1999
Creator: Mayer, Thomas M.; Michalske, Terry A. & Shinn, Neal D.
System: The UNT Digital Library
Stabilization of lead-rich low-level mixed wastes in chemically bonded phosphate ceramic. (open access)

Stabilization of lead-rich low-level mixed wastes in chemically bonded phosphate ceramic.

A chemically bonded magnesium potassium phosphate ceramic has been developed by an acid-base reaction at room temperature, for use in stabilizing U.S. Department of Energy low-level mixed waste streams that include hazardous metals and low-level radioactive elements. Using this ceramic, we solidified, in monolithic waste forms, low-level mixed waste streams containing various levels of PbCl{sub 2} and PbCO{sub 3}. These final waste forms were evaluated for their land disposal suitability. The results showed low open porosity (1.48-4.61 vol.%); hence, low permeability, and higher compression strengths (4310-6734 psi) that were one order of magnitude above that required. The level of lead in the leachate following the Toxicity Characteristic Leaching Procedure test was reduced from 50,000 to <0.1 ppm. Leachability indexes from the long-term leaching test (ANS 16.1 test) were between 11.9 and 13.6. This excellent lead retention is due to its chemical fixation as insoluble lead phosphate and to physical encapsulation by the phosphate matrix.
Date: August 10, 1999
Creator: Jeong, S.-Y.
System: The UNT Digital Library
ATLAS 10 GHz ECR ions source upgrade project. (open access)

ATLAS 10 GHz ECR ions source upgrade project.

A major upgrade of the first ATLAS 10 GHz ECR ion source, which began operations in 1987, is in the planning and procurement phase. The new design will convert the old two-stage source into a single-stage source with an electron donor disk and high gradient magnetic field that preserves radial access for solid material feeds and pumping of the plasma chamber. The new magnetic field profile allows for the possibility of a second ECR zone at a frequency of 14 GHz. An open hexapole configuration, using a high energy-product Nd-Fe-B magnet material, having an inner diameter of 8.8 cm and pole gaps of 2.4 cm has been adopted. Models indicate that the field strengths at the chamber wall, 4 cm in radius, will be 9.3 kG along the magnet poles and 5.6 kG along the pole gaps. The individual magnet bars will be housed in austenitic stainless steel allowing the magnet housing within the aluminum plasma chamber to be used as a water channel for direct cooling of the magnets. Eight solenoid coils from the existing ECR will be enclosed in an iron yoke to produce the axial mirror. Based on a current of 500 A, the final model predicts …
Date: August 10, 1999
Creator: Moehs, D. P.; Pardo, R. C.; Vondrasek, R. & Xie, D.
System: The UNT Digital Library
Alternatives to conventional diesel fuel-some potential implications of California's TAC decision on diesel particulate. (open access)

Alternatives to conventional diesel fuel-some potential implications of California's TAC decision on diesel particulate.

Limitations on the use of petroleum-based diesel fuel in California could occur pursuant to the 1998 declaration by California's Air Resources Board (CARB) that the particulate matter component of diesel exhaust is a carcinogen, therefore a toxic air contaminant (TAC) subject to provisions of the state's Proposition 65. It is the declared intention of CARB not to ban or restrict diesel fuel, per se, at this time. Assuming no total ban, Argonne National Laboratory (ANL) explored two feasible ''mid-course'' strategies. (1) Increased penetration of natural gas and greater gasoline use in the transportation fuels market, to the extent that some compression-ignition (CI) applications revert to spark-ignition (SI) engines. (2) New specifications requiring diesel fuel reformulation based on exhaust products of individual diesel fuel constituents. Each of these alternatives results in some degree of (conventional) diesel displacement. In the first case, diesel fuel is assumed admissible for ignition assistance as a pilot fuel in natural gas (NG)-powered heavy-duty vehicles, and gasoline demand in California increases by 32.2 million liters per day overall, about 21 percent above projected 2010 baseline demand. Natural gas demand increases by 13.6 million diesel liter equivalents per day, about 7 percent above projected (total) consumption level. In …
Date: August 10, 1999
Creator: Eberhardt, J. J.; Rote, D. M.; Saricks, C. L. & Stodolsky, F.
System: The UNT Digital Library
Hairpin vortex formation, a case study for unsteady visualization. (open access)

Hairpin vortex formation, a case study for unsteady visualization.

To better understand the vortex dynamics of coherent structures in turbulent and transitional boundary layers, we consider direct numerical simulation of the interaction between a flat-plateboundary-layer flow and an isolated hemispherical roughness element. Of principal interest is the evolution of hairpin vortices that form an interlacing pattern in the wake of the hemisphere, lift away from the wall, and are stretched by the shearing action of the boundary layer. Using animations of unsteady three-dimensional representations of this flow, produced by the vtk toolkit and enhanced to operate in a CAVE virtual environment, we identify and study several key features in the evolution of this complex vortex topology not previously observed in other visualization formats.
Date: August 10, 1999
Creator: Fischer, P. F.; Papka, M. E.; Szymanski, M. & Tufo, H. M.
System: The UNT Digital Library
High-dielectric-constant ferroelectric thin film and bulk ceramic capacitors for power electronics. (open access)

High-dielectric-constant ferroelectric thin film and bulk ceramic capacitors for power electronics.

Significant effort is presently focused on reducing the size and weight of power electronic modules. To achieve these goals in high-power capacitors, alternative materials and fabrication processes are needed. Thin film (<0.5 {micro}m) and bulk capacitors that use perovskite-based ferroelectric dielectrics are promising alternative technologies. Ferroelectrics possess high dielectric constants, thus offering substantial increases in volumetric capacitance. In thin film form, these materials display low loss and high breakdown strength. The unique properties of some of these materials, such as a nonlinear dielectric response or a high energy-storage capacity accompanying a phase change, can be exploited for power electronic capacitors. Prototype capacitors of two such materials, (Ba,Sr)TiO{sub 3} and PbZrO{sub 3}, have been fabricated in both thin film and bulk ceramic form. The influence of fabrication conditions on dielectric properties has been studied. Initial studies have demonstrated the viability of perovskite ferroelectrics for next-generation capacitor components.
Date: August 10, 1999
Creator: Auciello, O. H.; Baldo, P.; Baumann, P.; Erck, R. A.; Giumarra, J.; Im, J. et al.
System: The UNT Digital Library
The measurement of the mass of the W boson from the Tevatron. (open access)

The measurement of the mass of the W boson from the Tevatron.

This paper presents measurements of the mass of the W vector boson from the CDF and D0 experiments using data collected at {radical}s = 1.8 TeV during the 1994-1995 data taking run. CDF finds a preliminary mass of M{sub W} = 80.43 {+-} 0.16 GeV and D0 measures a mass of M{sub W} = 80.44 {+-} 0.12 GeV.
Date: August 10, 1999
Creator: Thurman-Keup, R.
System: The UNT Digital Library
The e sup + , e sup minus background at Relativistic Heavy Ion Collider (RHIC) generated by beam crossing (open access)

The e sup + , e sup minus background at Relativistic Heavy Ion Collider (RHIC) generated by beam crossing

At the Brookhaven Relativistic Heavy Ion Collider (RHIC), fully stripped heavy ions will circulate in each of two rings up to beam energies of 250 (Z/A) GeV/u. During the beam crossing, the peripheral electromagnetic interaction between the heavy ions is sufficient to induce copious production of di-lepton pairs. These pairs are a potential source of background for the detectors at RHIC. In this paper we discuss the expected number of e{sup +},e{sup {minus}} pairs, given the accepted initial luminosity value L of the collider. More importantly, we also calculate the differential cross sections for the angle, energy, rapidity and momentum distribution of the leptons. Using the luminosity L of the collider, these differential cross sections are normalized to the expected number of leptons per second. We restrict ourselves to e{sup +},e{sup {minus}} production, a discussion of {mu}{sup +},{mu}{sup {minus}} and {tau}{sup +}{tau}{sup {minus}} distributions will be published later. The results are presented for the expected worst case, namely {sup 197}Au{sup 79+} ions at a beam kinetic energy of 100 GeV/u. This is forseen to be the heaviest ion for high luminosity experiments at RHIC. We note for a given energy, the cross section for e{sup +},e{sup {minus}} production scales as …
Date: August 10, 1990
Creator: Rhoades-Brown, M.J.; Ludlam, T. (Brookhaven National Lab., Upton, NY (USA)); Wu, J.; Bottcher, C. & Strayer, M. (Oak Ridge National Lab., TN (USA))
System: The UNT Digital Library
Commentary on Future directions: Building technologies and design tools'' (open access)

Commentary on Future directions: Building technologies and design tools''

This paper presents a number of interesting and thought-provoking scenarios about the future use of advanced technology in the design and operation of commercial buildings. I will express my reactions in the following series of short paragraphs. These thoughts will, I hope, raise some new questions and offer fruitful directions for further exploration.
Date: August 10, 1992
Creator: Quadrel, R.W.
System: The UNT Digital Library
Demonstration of ultraviolet lasing with a low energy electron beam (open access)

Demonstration of ultraviolet lasing with a low energy electron beam

We report on the design details of the first ultraviolet (UV) free-electron laser (FEL) oscillator driven by low-energy electrons from a radio-frequency linear accelerator. In our experiment we used a high-current, high brightness electon beam in combination with a wiggler of novel design to produce an FEL that lased at wavelengths from 369--380 nm using 45.9--45.2 MeV electrons. In addition we performed a proof-of principle experiment that demonstrated the first ever photolithography on a photoresist-coated silicon wafer using an FEL light source.
Date: August 10, 1993
Creator: O`Shea, P. G.; Bender, S. C. & Byrd, D. A.
System: The UNT Digital Library
Burn rates of pristine and degraded explosives at elevated temperatures and pressures (open access)

Burn rates of pristine and degraded explosives at elevated temperatures and pressures

We measure the Laminar burn rates of explosives at extreme conditions (up to 520K and 1 GPa) in a hybrid strand burner, to provide reaction rate data for prediction of violence of thermal response. Data from a series of HMX-based explosives show that explosives with high binder content (15 wt%) burn smoothly over the entire pressure range regardless of particle size, while explosives with less binder eventually transition to a rapid erratic burn 10-100 times faster. When heated to ~ 440K, an HMX formulation with fine particles and 15% binder exhibits different burning behav- ior depending on the details of the temperature-pressure history, apparently as a result of the {beta} {yields} {delta} phase transition in HMX. Burn rates can be increased by 1000-fold under certain conditions.
Date: August 10, 1998
Creator: Chandler, J B & Maienschein, J L
System: The UNT Digital Library
The Spectroscopy of {sup 183}Tl: An Extreme Case of Prolate-Oblate Shape-Competition (open access)

The Spectroscopy of {sup 183}Tl: An Extreme Case of Prolate-Oblate Shape-Competition

The yrast sequence in {sup 183}Tl has been studied for the first time in recoil-mass and decay tagged gamma-ray spectroscopic measurements. A rotational-like cascade of seven transitions is observed down to the bandhead with spin 13/2+. In contrast to adjacent nuclei, links from the yrast band to a lower lying weakly deformed (oblate) structure are not observed. It appears that the prolate energy minimum in {sup 183}Tl drops significantly compared to {sup 185}Tl and minimizes below the neutron i13/2 midshell (n <= 102). Possibilities for the decay out of the band in {sup 183}Tl are discussed.
Date: August 10, 1998
Creator: Batchelder, J.C.; Bingham, C.R.; Carpenter, M.P.; Cizewski, J.A.; Gross, C.J.; Helariutta, K. et al.
System: The UNT Digital Library
Monte Carlo Methods and Applications for the Nuclear Shell Model (open access)

Monte Carlo Methods and Applications for the Nuclear Shell Model

The shell-model Monte Carlo (SMMC) technique transforms the traditional nuclear shell-model problem into a path-integral over auxiliary fields. We describe below the method and its applications to four physics issues: calculations of sd-pf-shell nuclei, a discussion of electron-capture rates in pf-shell nuclei, exploration of pairing correlations in unstable nuclei, and level densities in rare earth systems.
Date: August 10, 1998
Creator: Dean, D.J. & White, J.A.
System: The UNT Digital Library
Tau physics results from SLD (open access)

Tau physics results from SLD

Results on {tau} physics at SLD are presented. They are based on 4,316 {tau}-pair events selected from a 150 k Z{sup 0} data sample collected at the SLC. These results include measurements of the {tau} lifetime ({tau}{sub r} = 288.1 {+-} 6.1 {+-} 3.3 fs), the {tau} Michel parameters ({rho} = 0.71 {+-} 0.09 {+-} 0.04, {zeta} = 1.03 {+-} 0.36 {+-} 0.05, and {zeta}{delta} = 0.84 {+-} 0.27 {+-} 0.05), and the {tau} neutrino helicity (h{sub {nu}} = {minus}0.81 {+-} 0.18 {+-} 0.03).
Date: August 10, 1996
Creator: Daoudi, M.
System: The UNT Digital Library
Analysis of High-Fold Gamma Data (open access)

Analysis of High-Fold Gamma Data

Historically, {gamma}-{gamma} and {gamma}-{gamma}-{gamma} coincidence spectra were utilized to build nuclear level schemes. With the development of large detector arrays, it has became possible to analyze higher fold coincidence data sets. This paper briefly reports on software to analyze 4-fold coincidence data sets that allows creation of 4-fold histograms (hypercubes) of at least 1024 channels per side (corresponding to a 43 gigachannel data space) that will fit onto a few gigabytes of disk space, and extraction of triple-gated spectra in a few seconds. Future detector arrays may have even higher efficiencies, and detect an many as 15 or 20 {gamma} rays simultaneously; such data will require very different algorithms for storage and analysis. Difficulties inherent in the analysis of such data are discussed, and two possible new solutions are presented, namely adaptive list-mode systems and list-list-mode storage.
Date: August 10, 1998
Creator: Beyer, C.J.; Cromaz, M. & Radford, D.C.
System: The UNT Digital Library
Nuclear Structure Near the Drip Lines (open access)

Nuclear Structure Near the Drip Lines

Experiments with beams of unstable nuclei will make it possible to look closely into many aspects of the nuclear many-body problem. Theoretically, exotic nuclei represent a formidable challenge for the nuclear many-body theories and their power to predict nuclear properties in nuclear terra incognita.
Date: August 10, 1998
Creator: Nazarewicz, W.
System: The UNT Digital Library
Trends in robotics: A summary of the Department of Energy`s critical technology roadmap (open access)

Trends in robotics: A summary of the Department of Energy`s critical technology roadmap

Technology roadmaps serve as pathways to the future. They call attention to future needs for research and development; provide a structure for organizing technology forecasts and programs; and help communicate technological needs and expectations among end users and the research and development (R and D) community. Critical Technology roadmaps, of which the Robotics and Intelligent Machines (RIM) Roadmap is one example, focus on enabling or cross-cutting technologies that address the needs of multiple US Department of Energy (DOE) offices. Critical Technology roadmaps must be responsive to mission needs of the offices; must clearly indicate how the science and technology can improve DOE capabilities; and must describe an aggressive vision for the future of the technology itself. The RIM Roadmap defines a DOE research and development path for the period beginning today, and continuing through the year 2020. Its purpose is to identify, select and develop objectives that will satisfy near- and long-term challenges posed by DOE`s mission objectives. If implemented, this roadmap will support DOE`s mission needs while simultaneously advancing the state-of-the-art of RIM. For the purposes of this document, RIM refers to systems composed of machines, sensors, computers and software that deliver processes to DOE operations. The RIM Roadmap …
Date: August 10, 1998
Creator: Eicker, P. J.
System: The UNT Digital Library