Detector limitations, STAR (open access)

Detector limitations, STAR

Every detector has limitations in terms of solid angle, particular technologies chosen, cracks due to mechanical structure, etc. If all of the presently planned parts of STAR [Solenoidal Tracker At RHIC] were in place, these factors would not seriously limit our ability to exploit the spin physics possible in RHIC. What is of greater concern at the moment is the construction schedule for components such as the Electromagnetic Calorimeters, and the limited funding for various levels of triggers.
Date: July 13, 1998
Creator: Underwood, D. G.
Object Type: Article
System: The UNT Digital Library
Comparison of measured and calculated composition of irradiated EBR-II blanket assemblies. (open access)

Comparison of measured and calculated composition of irradiated EBR-II blanket assemblies.

In anticipation of processing irradiated EBR-II depleted uranium blanket subassemblies in the Fuel Conditioning Facility (FCF) at ANL-West, it has been possible to obtain a limited set of destructive chemical analyses of samples from a single EBR-II blanket subassembly. Comparison of calculated values with these measurements is being used to validate a depletion methodology based on a limited number of generic models of EBR-II to simulate the irradiation history of these subassemblies. Initial comparisons indicate these methods are adequate to meet the operations and material control and accountancy (MC and A) requirements for the FCF, but also indicate several shortcomings which may be corrected or improved.
Date: July 13, 1998
Creator: Grimm, K. N.
Object Type: Article
System: The UNT Digital Library
Superconducting nanostructured materials. (open access)

Superconducting nanostructured materials.

Within the last year it has been realized that the remarkable properties of superconducting thin films containing a periodic array of defects (such as sub-micron sized holes) offer a new route for developing a novel superconducting materials based on precise control of microstructure by modern photolithography. A superconductor is a material which, when cooled below a certain temperature, loses all resistance to electricity. This means that superconducting materials can carry large electrical currents without any energy loss--but there are limits to how much current can flow before superconductivity is destroyed. The current at which superconductivity breaks down is called the critical current. The value of the critical current is determined by the balance of Lorentz forces and pinning forces acting on the flux lines in the superconductor. Lorentz forces proportional to the current flow tend to drive the flux lines into motion, which dissipates energy and destroys zero resistance. Pinning forces created by isolated defects in the microstructure oppose flux line motion and increase the critical current. Many kinds of artificial pinning centers have been proposed and developed to increase critical current performance, ranging from dispersal of small non-superconducting second phases to creation of defects by proton, neutron or heavy …
Date: July 13, 1998
Creator: Metlushko, V.
Object Type: Article
System: The UNT Digital Library
Solving QCD using multi-regge theory. (open access)

Solving QCD using multi-regge theory.

This talk outlines the derivation of a high-energy, transverse momentum cut-off, solution of QCD in which the Regge pole and ''single gluon'' properties of the pomeron are directly related to the confinement and chiral symmetry breaking properties of the hadron spectrum. In first approximation, the pomeron is a single reggeized gluon plus a ''wee parton'' component that compensates for the color and particle properties of the gluon. This solution corresponds to a supercritical phase of Reggeon Field Theory.
Date: July 13, 1998
Creator: White, A. R.
Object Type: Article
System: The UNT Digital Library
Incorporation of measurement data from irradiated fuel samples into the MTG system at FCF. (open access)

Incorporation of measurement data from irradiated fuel samples into the MTG system at FCF.

The Mass Tracking (MTG) System for the Fuel Conditioning Facility (FCF) initially uses calculated values for the mass flows of irradiated EBR-II driver fuel to be processed in the electrorefiner. Validation of the methodology used to calculate these mass values was based on comparisons with measured values obtained on lead experimental subassemblies. Nevertheless, these calculated values are continually verified by measurements performed by the Analytical Laboratory on samples from the element chopper retained for each chopper batch. When the measured data become available, it is necessary to determine if the measured and calculated data are consistent. If so, the MTG System retains the ''best'' data, i.e., the data with the smallest uncertainties. If measured and calculated data are not consistent, measurements must be repeated on a backup sample, after which, again the ''best'' data are used by the MTG System. Knowledge of the uncertainties in both the measured and calculated data is fundamental both to determining whether the data are consistent and to determining which of the data are to be used. The present study uses the availability of a ''large'' number of measured data from the initial chopper batch to estimate uncertainties in the measured and calculated values. Then …
Date: July 13, 1998
Creator: McKnight, R. D.
Object Type: Article
System: The UNT Digital Library
Evolution of collective motion in light polonium nuclei. (open access)

Evolution of collective motion in light polonium nuclei.

The {gamma}-ray spectroscopy of even- and odd-mass isotopes of polonium have been studied using arrays of Ge detectors coupled to recoil-mass analyzers, including recoil-decay tagging techniques. The level energies and B(E2) branching ratios can be reproduced by theoretical frameworks which do not explicitly include proton particle-hole excitations across the Z = 82 shell, conclusions in contrast to those deduced from alpha-decay measurements.
Date: July 13, 1998
Creator: Cizewski, J. A.
Object Type: Article
System: The UNT Digital Library
Determination of transient gain lifetime for a 1-ps driven nickel like palladium 14.7 nm x-ray laser (open access)

Determination of transient gain lifetime for a 1-ps driven nickel like palladium 14.7 nm x-ray laser

None
Date: July 13, 1998
Creator: Dunn, J., LLNL
Object Type: Report
System: The UNT Digital Library
Hydrogen peroxide propulsion for smaller satellites (SSC98-VIII-1) (open access)

Hydrogen peroxide propulsion for smaller satellites (SSC98-VIII-1)

As satellite designs shrink, providing maneuvering and control capability falls outside the realm of available propulsion technology. While cold gas has been used on the smallest satellites, hydrogen peroxide propellant is suggested as the next step in performance and cost before hydrazine. Minimal toxicity and a small scale enable benchtop propellant preparation and development testing. Progress toward low-cost thrusters and self-pressurizing tank systems is described.
Date: July 13, 1998
Creator: Whitehead, J. C.
Object Type: Article
System: The UNT Digital Library
The characteristic analysis of a hybrid multifluid turbulent-mix model (open access)

The characteristic analysis of a hybrid multifluid turbulent-mix model

A thorough analysis of the characteristics of a multifluid turbulent mix model in the case of one-dimensional two phase flows is presented under various physical circumstances. It has been found that the new hybrid multifluid turbulent mix model has all real characteristics if either real or turbulent viscosity is present. When real viscosity vanishes, the model still has all real characteristics for zero relative motion between fluids. For nonzero relative motions between fluids, the model will have all real characteristics if the disordered motions and turbulent viscosity together are generated with the nonzero relative motions simultaneously. The implications of the results are further discussed.
Date: July 13, 1998
Creator: Cheng, B. & Cranfill, C. W.
Object Type: Report
System: The UNT Digital Library
New concept of small power reactor without on-site refueling for non-proliferation (open access)

New concept of small power reactor without on-site refueling for non-proliferation

Energy demand in developing countries is increasing to support growing populations and economies. This demand is expected to continue growing at a rapid pace well into the next century. Because current power sources, including fossil, renewable, and nuclear, cannot meet energy demands, many developing countries are interested in building a new generation of small reactor systems to help meet their needs. The U.S. recognizes the need for energy in the developing countries. In its 1998 Comprehensive Energy Strategy, the Department of Energy calls for research into low-cost, proliferation- resistant, nuclear reactor technologies to ensure that this demand can be met in a manner consistent with U.S. non-proliferation goals and policies. This research has two primary thrusts: first, the development of a small proliferation-resistant nuclear system (i.e., a technology focus); second, the continuation of open communication with the international community through early engagement and cooperation on small reactor development. A system that meets developing country requirements must: (1) achieve reliably safe operation with a minimum of maintenance and supporting infrastructure; (2) offer economic competitiveness with alternative energy sources available to the candidate sites; and (3) demonstrate significant improvements in proliferation resistance relative to existing reactor systems. These challenges are the most …
Date: July 13, 1998
Creator: Brown, N.W., LLNL
Object Type: Article
System: The UNT Digital Library
Specification for movable manipulator system for use in radiochemical engineering cells (open access)

Specification for movable manipulator system for use in radiochemical engineering cells

This specification was prepared to identify requirements for a movable manipulator for use in B-Ccl 1 and the REC Airlock at 324 Building. This manipulator could also be used in other hot cells at the 324 Building. This work involves retrieval, inspection, reduction and decontamination of material on the Airlock and Cell floors, in the pipe trench and on the walls. B and W Hanford Company (BWHC) recognizes that not all of the requirements are compatible and some may need to be changed, subject to agreement between the parties involved. BWHC also recognizes that in order to perform the tasks described two or more different machines with significantly different layout may be necessary. These requirements are the starting point for any proposal.
Date: July 13, 1998
Creator: Dixson, G.E.
Object Type: Report
System: The UNT Digital Library
Development of a Graphical User Interface to Visualize Surface Observations (open access)

Development of a Graphical User Interface to Visualize Surface Observations

Thousands of worldwide observing stations provide meteorological information near the earth's surface as often as once each hour. This surface data may be plotted on geographical maps to provide the meteorologist useful information regarding weather patterns for a region of interest. This report describes the components and applications of a graphical user interface which have been developed to visualize surface observations at any global location and time of interest.
Date: July 13, 1998
Creator: Buckley, Robert L.
Object Type: Report
System: The UNT Digital Library
High Throughput and Reliability (HITaR) (open access)

High Throughput and Reliability (HITaR)

None
Date: July 13, 1998
Creator: Robinson, S. C.; Pollard, R. E.; Ayers, C. W.; Haynes, H. D.; Hively, L. M.; Curless, Richard et al.
Object Type: Report
System: The UNT Digital Library
Finite element analysis of constrained total Condylar Knee Prosthesis (open access)

Finite element analysis of constrained total Condylar Knee Prosthesis

Exactech, Inc., is a prosthetic joint manufacturer based in Gainesville, FL. The company set the goal of developing a highly effective prosthetic articulation, based on scientific principles, not trial and error. They developed an evolutionary design for a total knee arthroplasty system that promised improved performance. They performed static load tests in the laboratory with similar previous designs, but dynamic laboratory testing was both difficult to perform and prohibitively expensive for a small business to undertake. Laboratory testing also cannot measure stress levels in the interior of the prosthesis where failures are known to initiate. To fully optimize their designs for knee arthroplasty revisions, they needed range-of-motion stress/strain data at interior as well as exterior locations within the prosthesis. LLNL developed computer software (especially NIKE3D) specifically designed to perform stress/strain computations (finite element analysis) for complex geometries in large displacement/large deformation conditions. Additionally, LLNL had developed a high fidelity knee model for other analytical purposes. The analysis desired by Exactech could readily be performed using NIKE3D and a modified version of the high fidelity knee that contained the geometry of the condylar knee components. The LLNL high fidelity knee model was a finite element computer model which would not be …
Date: July 13, 1998
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Formal solution for the fields within a beam-bug calibrator (open access)

Formal solution for the fields within a beam-bug calibrator

For some time I was bothered by the fact that measurements of offsets in the various bug calibration setups never agreed with the simple formulae (2) used for determining electron beam position in the Livermore induction linacs and transport systems. About 1983 I realized that the discrepancy arises from the way the bug calibrator simulates an electron beam in a conducting pipe. At that time I solved the problem using the method presented here. Unfortunately, I did not write it up at that time. After considerable effort, I was able to repeat the calculation. Since I have little confidence that after a few years I could ever do it again, I felt obliged to write it up in some detail. Our beam bug calibrator consists of two conducting cylinders, nominally concentric, that simulate the electron beam within a drift tube. The radii of the larger cylinder is 2.3 times that of the smaller giving an electrical impedance of 50 Ohms to the coaxial combination. To simulate a beam off-axis within a drift tube, the inner tube is moved relative to the outer tube. This only approximately simulates the motion of a beam because the surface current on the inner tube …
Date: July 13, 1998
Creator: Fessenden, T J
Object Type: Report
System: The UNT Digital Library
Taiwan: Texts of the Taiwan Relations Act, the U.S. - China Communiques, and the "Six Assurances" (open access)

Taiwan: Texts of the Taiwan Relations Act, the U.S. - China Communiques, and the "Six Assurances"

This report discusses the U.S. policy on Taiwan, which is governed by the Taiwan Relations Act (TRA), the 3 U.S. joint communiqués with China, and the so-called "Six Assurances" on Taiwan.
Date: July 13, 1998
Creator: Dumbaugh, Kerry
Object Type: Report
System: The UNT Digital Library
Development of a Graphical User Interface to Visualize Surface Observations (open access)

Development of a Graphical User Interface to Visualize Surface Observations

Thousands of worldwide observing stations provide meteorological information near the earth's surface as often as once each hour. This surface data may be plotted on geographical maps to provide the meteorologist useful information regarding weather patterns for a region of interest. This report describes the components and applications of a graphical user interface which have been developed to visualize surface observations at any global location and time of interest.
Date: July 13, 1998
Creator: Buckley, R. L.
Object Type: Report
System: The UNT Digital Library