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2,043 Matching Results
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Methods and procedures for evaluation of neutron-induced activation cross sections
One cannot expect measurements alone to supply all of the neutron-induced activation cross-section data required by the fission reactor, fusion reactor, and nuclear weapons development communities, given the wide ranges of incident neutron energies, the great variety of possible reaction types leading to activation, and targets both stable and unstable. Therefore, the evaluator must look to nuclear model calculations and systematics to aid in fulfilling these cross-section data needs. This review presents some of the recent developments and improvements in the prediction of neutron activation cross sections, with specific emphasis on the use of empirical and semiempirical methods. Since such systematics require much less nuclear informaion as input and much less computational time than do the multistep Hauser-Feshbach codes, they can often provide certain cross-section data at a sufficient level of accuracy within a minimum amount of time. The cross-section information that these systematics can and cannot provide and those cases in which they can be used most reliably are discussed.
Date:
September 1, 1981
Creator:
Gardner, M.A.
System:
The UNT Digital Library
Statistical vs valence neutron neutron capture in /sup 98/Mo
It has often been reported that, in mass regions corresponding to peaks in the neutron strength function, nonstatistical mechanisms contribute a significant or even major portion of the average radiation width in the beginning of the resonance region. This could severely limit the possibility of calculating caputure cross sections for targets where experimental data are lacking, because such direct effects are sensitive to the detailed nuclear level structure in the daughter nucleus. The reaction /sup 98/Mo+n was examined for neutrons in the 1 keV to 3 MeV energy range, because this case is often cited as one of the clearest examples of valence neutron capture effects. Preliminary calculations are presented which suggest that these nonstatistical effects rapidly disappear when measurements from even a small number of resonances are averaged.
Date:
June 19, 1981
Creator:
Gardner, D. G.
System:
The UNT Digital Library
Current status of fast-neutron-capture calculations
This work is primarily concerned with the calculation of neutron capture cross sections and capture gamma-ray spectra, in the framework of the Hauser-Feshbach statistical model and for neutrons from the resonance region up to several MeV. An argument is made that, for applied purposes such as constructing evaluated cross-section libraries, nonstatistical capture mechanisms may be completely neglected at low energies and adequately approximated at high energies in a simple way. The use of gamma-ray strength functions to obtain radiation widths is emphasized. Using the reaction /sup 89/Y + n as an example, the problems encountered in trying to construct a case that could be run equivalently on two different nuclear reaction codes are illustrated, and the effects produced by certain parameter variations are discussed.
Date:
April 15, 1982
Creator:
Gardner, D. G.
System:
The UNT Digital Library
Thin film porous membranes for catalytic sensors
This paper reports on new and surprising experimental data for catalytic film gas sensing resistors coated with nanoporous sol-gel films to impart selectivity and durability to the sensor structure. This work is the result of attempts to build selectivity and reactivity to the surface of a sensor by modifying it with a series of sol-gel layers. The initial sol-gel SiO{sub 2} layer applied to the sensor surprisingly showed enhanced O{sub 2} interaction with H{sub 2} and reduced susceptibility to poisons such as H{sub 2}S.
Date:
June 1, 1997
Creator:
Hughes, R.C.; Boyle, T.J. & Gardner, T.J.
System:
The UNT Digital Library
Development of a thermoacoustic natural gas liquefier.
Praxair, in conjunction with the Los Alamos National Laboratory, is developing a new technology, thermoacoustic heat engines and refrigerators, for liquefaction of natural gas. This is the only technology capable of producing refrigeration power at cryogenic temperatures with no moving parts. A prototype, with a projected natural gas liquefaction capacity of 500 gallons/day, has been built and tested. The power source is a natural gas burner. Systems will be developed with liquefaction capacities up to 10,000 to 20,000 gallons per day. The technology, the development project, accomplishments and applications are discussed. In February 2001 Praxair, Inc. purchased the acoustic heat engine and refrigeration development program from Chart Industries. Chart (formerly Cryenco, which Chart purchased in 1997) and Los Alamos had been working on the technology development program since 1994. The purchase included assets and intellectual property rights for thermoacoustically driven orifice pulse tube refrigerators (TADOPTR), a new and revolutionary Thermoacoustic Stirling Heat Engine (TASHE) technology, aspects of Orifice Pulse Tube Refrigeration (OPTR) and linear motor compressors as OPTR drivers. Praxair, in cooperation with Los Alamos National Laboratory (LANL), the licensor of the TADOPTR and TASHE patents, is continuing the development of TASHE-OPTR natural gas powered, natural gas liquefiers. The liquefaction …
Date:
January 1, 2002
Creator:
Wollan, John J.; Swift, Gregory W.; Backhaus, Scott N. & Gardner, David L.
System:
The UNT Digital Library
Necrology, Summer 1944
Column documenting biographical information about Oklahomans who have died, including Thomas Mayberry Randolph, Joseph Patrick O’Brien, James J. Savage, and Albert Lyman Welsh.
Date:
Summer 1944
Creator:
Moore, Jessie Randolph & Oklahoma Historical Society
System:
The Gateway to Oklahoma History
Spectral shaping and phase control of a fast-wave current drive antenna array
The requirements for antenna design and phase control circuitry for a fast-wave current drive (FWCD) array operating in the ion cyclotron range of frequencies are considered. The design of a phase control system that can operate at arbitrary phasing over a wide range of plasma-loading and strap-coupling values is presented for a four-loop antenna array, prototypical of an array planned for the DIII-D tokamak (General Atomics, San Diego, California). The goal is to maximize the power launched with the proper polarization for current drive while maintaining external control of phase. Since it is desirable to demonstrate the feasibility of FWCD prior to ITER, a four-strap array has been designed for DIII-D to operate with the existing 2-MW transmitter at 60 MHz. 3 refs., 6 figs.
Date:
January 1, 1989
Creator:
Baity, F. W.; Gardner, W. L.; Goulding, R. H.; Hoffman, D. J. & Ryan, P. M.
System:
The UNT Digital Library
History and results of VC-1, the first CSDP corehole in Valles caldera, New Mexico
Valles Caldera No. 1 (VC-1) is the first Continental Scientific Drilling Program (CSDP) corehole drilled in the Valles caldera and the first continuously cored hole in the caldera region. The objectives of VC-1 were to penetrate a hydrothermal outflow plume near its source, to obtain structural and stratigraphic information near the intersection of the ring-fracture zone and the pre-caldera Jemez fault zone, and to core the youngest volcanic unit inside the caldera (Banco Bonito obsidian, 0.13 Ma). VC-1 penetrates 298 m of moat volcanics and caldera-fill ignimbrites, 35 m of pre-caldera volcaniclastic breccia, and 523 m of Paleozoic carbonates, sandstones and shales, with over 95% core recovery. Hydrothermal alterations are concentrated in sheared, brecciated and fractured zones from the volcaniclastic breccia to total depth with both the intensity and rank of alterations increasing with depth. Alterations consist primarily of clays, calcite, pyrite, quartz, and chlorite, but chalcopyrite has been identified as high as 518 m and molybdenite has been identified in a fractured zone at 847 m. Thermal aquifers were penetrated at various intervals from about 510 m on down. 11 refs., 5 figs.
Date:
January 1, 1985
Creator:
Goff, F.; Rowley, J.; Gardner, J.N.; Hawkins, W.; Goff, S.; Pisto, L. et al.
System:
The UNT Digital Library
Structural safety features for superconducting magnets
A survey has been carried out for various potential structural safety problems of superconducting fusion magnets. These areas include: (1) Stresses due to inhomogeneous temperature distributions in magnets where normal regions have been initiated. (2) Stress distributions and yield forces due to cracks and failed regions. (3) Superconducting magnet response due to seismic excitation. These analyses have been carried out using a variety of large capacity finite element computer codes that allow for the evaluation of stresses in elastic or elastic-plastic zones and around singularities in the magnet structure. Thus far, these analyses have been carried out on UWMAK-I type magnet systems. (auth)
Date:
January 1, 1975
Creator:
Lehner, J.; Reich, M.; Powell, J.; Bezler, P.; Gardner, D.; Yu, W. et al.
System:
The UNT Digital Library
The ICRF antennas for TFTR
Two compact loop antennas have been designed to provide ion cyclotron resonant frequency (ICRF) heating for TFTR. The antennas can convey a total of 10 MW to accomplish core heating in either high-density or high-temperature plasmas. The near-term goal of heating TFTR plasmas and the longer-term goals of ease in handling (for remote maintenance) and high reliability (in an inaccessible tritium tokamak environment) were major considerations in the antenna designs. The compact loop configuration facilitates handling because the antennas fit completely through their ports. Conservative design and extensive testing were used to attain the reliability required for TFTR. This paper summarizes how these antennas will accomplish these goals. 5 figs, 1 tab.
Date:
January 1, 1988
Creator:
Hoffman, D. J.; Colestock, P. L.; Gardner, W. L.; Hosea, J. C.; Nagy, A.; Stevens, J. et al.
System:
The UNT Digital Library
Measurement of the W boson helicity in top quark decay at D0
The authors present a measurement of the fraction f{sub +} of right-handed W bosons produced in top quark decays, based on a candidate sample of t{bar t} events in the {ell}+jets and dilepton decay channels corresponding to an integrated luminosity of 370 pb{sup -1} collected by the D0 detector at the Fermilab Tevatron p{bar p} Collider at {radical}s = 1.96 TeV. They reconstruct the decay angle {theta}* for each lepton. By comparing the cos{theta}* distribution from the data with those for the expected background and signal for various values of f{sub +}, they find f{sub +} = 0.056 {+-} 0.080(stat) {+-} 0.057(syst). (f{sub +} < 0.23 at 95% C.L.), consistent with the standard model prediction of f{sub +} = 3.6 x 10{sup -4}.
Date:
September 1, 2006
Creator:
Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
System:
The UNT Digital Library
HAMMER COURSEWARE MANAGEMENT SYSTEM (CMS) SYSTEM DEVELOPMENT AND IMPLEMENTATION
HAMMER Courseware Management System (HAMMERCMS) is the official name of the system Fluor Hanford, Inc., uses to facilitate development of, deliver, and track training presented in some electronic form (mainly, web-based training) to Hanford Site employees, subcontractors, and vendors.
Date:
April 28, 2006
Creator:
GARDNER, P.R.
System:
The UNT Digital Library
Model calculations as one means of satisfying the neutron cross-section requirements of the CTR program
None
Date:
February 26, 1975
Creator:
Gardner, D. G.
System:
The UNT Digital Library
SUDOKU A STORY & A SOLVER
Sudoku, also known as Number Place, is a logic-based placement puzzle. The aim of the puzzle is to enter a numerical digit from 1 through 9 in each cell of a 9 x 9 grid made up of 3 x 3 subgrids (called ''regions''), starting with various digits given in some cells (the ''givens''). Each row, column, and region must contain only one instance of each numeral. Completing the puzzle requires patience and logical ability. Although first published in a U.S. puzzle magazine in 1979, Sudoku initially caught on in Japan in 1986 and attained international popularity in 2005. Last fall, after noticing Sudoku puzzles in some newspapers and magazines, I attempted a few just to see how hard they were. Of course, the difficulties varied considerably. ''Obviously'' one could use Trial and Error but all the advice was to ''Use Logic''. Thinking to flex, and strengthen, those powers, I began to tackle the puzzles systematically. That is, when I discovered a new tactical rule, I would write it down, eventually generating a list of ten or so, with some having overlap. They served pretty well except for the more difficult puzzles, but even then I managed to develop an …
Date:
April 1, 2006
Creator:
GARDNER, P.R.
System:
The UNT Digital Library
An Alternative Lattice for the Spallation Neutron Source Accumulator Ring.
As a key component of the Spallation Neutron Source (SNS) Project, the Accumulator Ring will collect the proton beam from the SNS LINAC at an intensity of 2 x 10{sup 14} per pulse at 60 Hz for a total power of 2 MW, exceeding present performance value of existing facilities. Requirements of minimum beam loss for hands-on maintenance and flexibility for future upgrade are essential for the lattice design. In this paper, we study an alternative lattice emphasizing various injection schemes and flexibility for future upgrade. Working points, sextupole families for chromaticity control, and alternate extraction schemes are also considered.
Date:
March 29, 1999
Creator:
Gardner, C. J.; Lee, Y. Y.; Tsoupas, N. & Wei, J.
System:
The UNT Digital Library
Correction Systems Upgrade for the Sns Ring.
In view of the changes in the design of the SNS ring from the original FODO lattice [l] to the 220m hybrid lattice [2] and finally 1.3GeV compatible 248m ring [3], complementary studies have been undertaken, in order to upgrade its correction packages. We review the evolution of the correction systems and present the accelerator physics studies for the adopted schemes and powering plan.
Date:
June 18, 2001
Creator:
Papaphilippou, Y.; GARDNER, C. J.; Lee, Y. Y. & Wei, J.
System:
The UNT Digital Library
Applications of level structure modeling of odd-odd deformed nuclei
None
Date:
December 4, 1984
Creator:
Hoff, R. W.; Gardner, D. G.; Gardner, M. A.; Kern, J.; Piepenbring, R.; Boisson, J. P. et al.
System:
The UNT Digital Library
Design and Preliminary Monte Carlo Calculations of an Active Compton Suppressed LaBr3(Ce) Detector System for TRU Assay in Remote-Handled Wastes
Recent studies indicate LaBr3(Ce) scintillation detectors have desirable attributes, such as room temperature operability, which may make them viable alternatives as primary detectors (PD) in a Compton suppression spectrometer (CSS) used for remote-handled transuranic (RH-TRU) waste assay. A CSS with a LaBr3(Ce) PD has been designed and its expected performance evaluated using Monte Carlo analysis. The unique design of this unit minimizes the amount of "dead" material between the PD and the secondary guard detector. The analysis results indicate that this detector will have a relatively high Compton-suppression capability, with greater suppression ability for large angle-scattered photons in the PD. J. K. Hartwell1, M. E. McIlwain1, R. P. Gardner2, J. Kulisek3 1) Idaho National Laboratory, PO Box 1625, Idaho Falls, ID 83415-2114 USA 2) North Carolina State University, Dept of Nuclear Eng., PO Box 7909, Raleigh, NC 27695 USA 3) Ohio State University, Columbus, Ohio 43210 The US Department of Energy’s transuranic (TRU) waste inventory includes about 4,500 m3 of remote-handled TRU (RH-TRU) wastes. The RH-TRU waste stream is composed of a variety of containerized waste forms having a contact surface dose rate that exceeds 2 mSv/hr (200 mrem/hr) containing waste materials with a total TRU concentration greater than 3700 …
Date:
September 1, 2006
Creator:
Kulisek, J.; Hartwell, J. K.; McIlwain, M. E. & Gardner, R. P.
System:
The UNT Digital Library
Discrete Symmetries on the Light Front and a General Relation connecting Nucleon Electric Dipole and Anomalous Magnetic Moments
We consider the electric dipole form factor, F{sub 3}(q{sup 2}), as well as the Dirac and Pauli form factors, F{sub 1}(q{sup 2}) and F{sub 2}(q{sup 2}), of the nucleon in the light-front formalism. We derive an exact formula for F{sub 3}(q{sup 2}) to complement those known for F{sub 1}(q{sup 2}) and F{sub 2}(q{sup 2}). We derive the light-front representation of the discrete symmetry transformations and show that time-reversal- and parity-odd effects are captured by phases in the light-front wave functions. We thus determine that the contributions to F{sub 2}(q{sup 2}) and F{sub 3}(q{sup 2}), Fock-state by Fock-state, are related, independent of the fundamental mechanism through which CP violation is generated. Our relation is not specific to the nucleon, but, rather, is true of spin-1/2 systems in general, be they lepton or baryon. The empirical values of the anomalous magnetic moments, in concert with empirical bounds on the associated electric dipole moments, can better constrain theories of CP violation. In particular, we find that the neutron and proton electric dipole moments echo the isospin structure of the anomalous magnetic moments, {kappa}{sup n} {approx} -{kappa}{sup p}.
Date:
January 11, 2006
Creator:
Brodsky, Stanley J.; Gardner, Susan & Hwang, Dae Sung
System:
The UNT Digital Library
Analysis of resonance-driving imperfections in the AGS Booster
At the design intensity of 1.5 {times} 10{sup 13} ppp, the space charge tune shift in the AGS Booster at injection has been estimated to be about 0.35. The beam tunes are therefore spread over many lower order resonance lines and the associated stopbands must be corrected in order to minimize the amplitude growth due to resonance excitation. This requires proper compensation of the resonance-driving harmonics which result from random magnetic field errors. The observation and correction of second and third order resonance stopbands in the AGS Booster is reviewed, and an analysis of magnetic field imperfections based on the required corrections is given.
Date:
August 1, 1994
Creator:
Gardner, C.; Shoji, Y.; Danby, G.; Glenn, J. W.; Jackson, G. J.; Soukas, A. et al.
System:
The UNT Digital Library
Cycling indices for ecosystem models
The study of ecosystems is aided by representing structural and functional groups of organisms or processes as discrete components. A complex compartment model will explicitly map pathways from one compartment to another and specify transfer rates. This quantitative description allows insight into the dynamics of flow of nutrients, toxic chemicals, radionuclides, or energy. Three new indices that calculate compartment-specific probabilities of occurrence and recycling and illustrate the problem of applying these indices to ecosystem models are presented.
Date:
January 1, 1979
Creator:
Carney, J. H.; Gardner, R. H.; Mankin, J. B. & DeAngelis, D. L.
System:
The UNT Digital Library
Measurements and Modeling of Eddy Current Effects in BNL's AGS Booster.
Recent beam experiments at BNL's AGS Booster have enabled us to study in more detail the effects of eddy currents on the lattice structure and our control over the betatron tune. The Booster is capable of operating at ramp rates as high as 9 T/sec. At these ramp rates eddy currents in the vacuum chambers significantly alter the fields and gradients seen by the beam as it is accelerated. The Booster was designed with these effects in mind and to help control the field uniformity and linearity in the Booster Dipoles special vacuum chambers were designed with current windings to negate the affect of the induced eddy currents. In this report results from betatron tune measurements and eddy current simulations will be presented. We will then present results from modeling the accelerator using the results of the magnetic field simulations and compare these to the measurements.
Date:
June 23, 2006
Creator:
Brown, K. A.; Ahrens, L.; Gardner, C.; Glenn, J. W.; Harvey, M.; Meng, W. et al.
System:
The UNT Digital Library
Bioinformatics for Diagnostics, Forensics, and Virulence Characterization and Detection
We summarize four of our group's high-risk/high-payoff research projects funded by the Intelligence Technology Innovation Center (ITIC) in conjunction with our DHS-funded pathogen informatics activities. These are (1) quantitative assessment of genomic sequencing needs to predict high quality DNA and protein signatures for detection, and comparison of draft versus finished sequences for diagnostic signature prediction; (2) development of forensic software to identify SNP and PCR-RFLP variations from a large number of viral pathogen sequences and optimization of the selection of markers for maximum discrimination of those sequences; (3) prediction of signatures for the detection of virulence, antibiotic resistance, and toxin genes and genetic engineering markers in bacteria; (4) bioinformatic characterization of virulence factors to rapidly screen genomic data for potential genes with similar functions and to elucidate potential health threats in novel organisms. The results of (1) are being used by policy makers to set national sequencing priorities. Analyses from (2) are being used in collaborations with the CDC to genotype and characterize many variola strains, and reports from these collaborations have been made to the President. We also determined SNPs for serotype and strain discrimination of 126 foot and mouth disease virus (FMDV) genomes. For (3), currently >1000 probes …
Date:
April 5, 2005
Creator:
Gardner, S & Slezak, T
System:
The UNT Digital Library
Oak Ridge rf test facility
The ORNL RF Test Facility is to provide a national facility for the testing and evaluation of steady state, high-power (approx.1.0-MW) Ion Cyclotron Resonance Heating (ICRH) systems and components. The facility configuration consists of a vacuum vessel and two fully tested superconducting development magnets from the EBT-P program, arranged as a simple mirror of mirror ratio 4.8. The axial centerline distance between magnet throat centers is 112 cm. The vacuum vessel cavity has a large port (74 by 163 cm) and a test volume adequate for testing prototypic launchers for DIII-D and TFTR. The magnets are capable of generating a steady state field of approx.3 T on axis in the magnet throats. Steady state plasmas are generated in the facility by cyclotron resonance breakdown using a dedicated 200-kW, 28-GHz gyrotron. Rf sources are available covering a frequency range of 2 to 200 MHz at 1.5 kW and 3 to 18 MHz at 200 kW with several sources at intermediate parameters. Available in July 1986 will be a >1.0-MW, cw source spanning 40 to 80 MHz. The report consists of nine viewgraphs.
Date:
January 1, 1985
Creator:
Gardner, W.L.; Hoffman, D.J.; McCurdy, H.C.; McManamy, T.J.; Moeller, J.A. & Ryan, P.M.
System:
The UNT Digital Library