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Evidence for the Absence of Gluon Orbital Angular Momentum in the Nucleon
The Sivers mechanism for the single-spin asymmetry in unpolarized lepton scattering from a transversely polarized nucleon is driven by the orbital angular momentum carried by its quark and gluon constituents, combined with QCD final-state interactions. Both quark and gluon mechanisms can generate such a single-spin asymmetry, though only the quark mechanism can explain the small single-spin asymmetry measured by the COMPASS collaboration on the deuteron, suggesting the gluon mechanism is small relative to the quark mechanism. We detail empirical studies through which the gluon and quark orbital angular momentum contributions, quark-flavor by quark-flavor, can be elucidated.
Date:
August 23, 2006
Creator:
Brodsky, S. J. & Gardner, S.
System:
The UNT Digital Library
Some tools of the trade we`ve developed for our cross-section calculations
A number of compute codes have been modified or developed, both main-frame and PC. Seven codes, of which three are discussed in some detail. The later are: a controller-driven, double-precision version of the coupled-channel code ECIS; the latest version of STAPRE, a precompound plus Hauser-Feshbach nuclear reaction code; and NUSTART, a PC code that analyzes large sets of discrete nuclear levels and the multipole transitions among them. All main-frame codes are now being converted to the UNICOS operating system.
Date:
November 1, 1992
Creator:
Gardner, D. G. & Gardner, M. A.
System:
The UNT Digital Library
Difficulties with inferring neutron cross sections from charged-particle reactions
We have investigated problems associated with inferring cross sections for neutron reactions on unstable nuclei in the mass-90 region from charged-particle reactions on nearby stable targets. We conclude that effects due to precompound evaporation, isospin, and multiple reaction paths severely limit the circumstances under which charged-particle studies may be directly and easily converted to neutron cross sections of useful accuracy. 4 refs., 2 figs.
Date:
May 7, 1985
Creator:
Gardner, D. G. & Gardner, M. A.
System:
The UNT Digital Library
Setup and Performance of the Rhic Injector Accelerators for the 2005 Run With Copper Ions.
Copper ions for the 2005 run [1] of the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) are accelerated in the Tandem, Booster and AGS prior to injection into RHIC. The setup and performance of these accelerators with copper are reviewed in this paper.
Date:
May 16, 2005
Creator:
Ahrens, L.; Alessi, J. & Gardner, C. J.
System:
The UNT Digital Library
Continued study of the parameterization of the El gamma-ray strength function
The parameterization of the magnitude and the energy dependence of the E1 gamma-ray strength function for the calculation of neutron- and proton-induced capture cross sections and capture gamma-ray spectra is investigated. The energy-dependent Breit-Wigner (EDBW) is reparameterized incorporating a more general expression for the Breit-Wigner line shape. Evaluation of the reparameterized E1 gamma-ray strength function is discussed. (WHK)
Date:
June 19, 1981
Creator:
Gardner, M. A. & Gardner, D. G.
System:
The UNT Digital Library
Calculated neutron capture cross sections for the ground states and isomers of /sup 93/ /sup 94/ and /sup 95/Nb. [Resolved resonance region to 4 MeV, strength functions, statistical model]
Neutron-induced capture cross sections for the ground states and first isomeric states of /sup 93/Nb, /sup 94/Nb and /sup 95/Nb were studied from the resolved resonance region to 4 MeV via statistical model calculations. The production of isomers was included. Inelastic scattering cross sections and gamma-ray production spectra were also calculated. The anti GAMMA/ sub ..gamma..//D ratios were derived from gamma-ray strength function systematics. Total capture cross sections on the ground states are found to be within a factor of two of each other. Capture cross sections on the isomeric targets are important as well, not only because of their magnitude but also because of the significant population of these isomeric levels by inelastic scattering. 10 references.
Date:
September 1, 1978
Creator:
Gardner, M. A. & Gardner, D. G.
System:
The UNT Digital Library
Importance of level structure in nuclear reaction cross-section calculations. Revision 1
It is shown that level-density expressions cannot adequately represent or substitute for level structure information when making calculations of the Hauser-Feshbach type for cross sections or isomer-ratios for nuclei in the first few MeV above their ground state. It is stated that such discrete level information should include both experimentally confirmed and theoretically predicted levels. The utility of discrete level information to optimize level density calculations, to compute isomer ratios, in deriving dipole strength functions, and in the analysis of primary gamma ray spectra is emphasized, especially for nuclei far from the line of stability. 29 refs., 12 figs., 6 tabs. (DWL)
Date:
November 7, 1985
Creator:
Gardner, M. A. & Gardner, D. G.
System:
The UNT Digital Library
Calculated cross sections for production and destruction of some long-lived nuclides of importance in fusion energy applications
Knowledge of the production and destruction of long-lived species via neutrons, photons, and charged-particles is required in many fusion energy applications, such as reactor first-wall and blanket design, radioactive waste management, etc. Here we describe our calculational results for the production, via the (n,2n) reaction, of the following long-lived species: {sup 150}Eu(t{sub 1/2} = 36 y), {sup 152}Eu(t{sub 1/2} = 13 y), and {sup 192m2}Ir(t{sub 1/2} = 241 y). Some comments on calculations that we`ve made for destruction reactions of these species are also included.
Date:
July 8, 1993
Creator:
Gardner, M. A. & Gardner, D. G.
System:
The UNT Digital Library
Some limitations of detailed balance for inverse reaction calculations in the astrophysical p-process
p-Process modeling of some rare but stable proton-rich nuclei requires knowledge of a variety of neutron, charged particle, and photonuclear reaction rates at temperatures of 2 to 3 {times} 10{sup 9} {degrees}K. Detailed balance is usually invoked to obtain the stellar photonuclear rates, in spite of a number of well-known constraints. In this work we attempt to calculate directly the stellar rates for ({gamma},n) and ({gamma},{alpha}) reactions on {sup 151}Eu. These are compared with stellar rates obtained from detailed balance, using the same input parameters for the stellar (n,{gamma}) and ({alpha},{gamma}) reactions on {sup 150}Eu and {sup 147}Pm, respectively. The two methods yielded somewhat different results, which will be discussed along with some sensitivity studies. 16 refs., 7 figs.
Date:
December 5, 1990
Creator:
Gardner, D. G. & Gardner, M. A.
System:
The UNT Digital Library
Capture cross section and gamma-ray spectrum calculations for medium-weight nuclei. [Double-peak, energy-dependent Breit-Wigner model]
A double-peak, energy-dependent Breit-Wigner model of the E1 gamma-ray strength function was applied to nuclei from As to Rh, to predict their neutron capture cross sections and capture gamma-ray spectra. A consistent set of model parameters was obtained in this mass region to describe the step in the low-energy tail of the E1 strength function. This step allows agreement with photonuclear data at high energies, the correct GAMMA/sub gamma/ to be obtained for agreement with neutron capture cross-section data, and the calculation of the observed hardness in the capture gamma-ray spectra. For nuclei at or near the closed, N = 50 shell, however, the double-peak assumption breaks down. In these cases, good results are still obtained if the same set of model parameters is applied, except that the E1 strength function is formulated in terms of the first, narrower peak. 8 figures.
Date:
November 14, 1979
Creator:
Gardner, M. A. & Gardner, D. G.
System:
The UNT Digital Library
ORNL 150 keV neutral beam test facility
The 150 keV neutral beam test facility provides for the testing and development of neutral beam injectors and beam systems of the class that will be needed for the Tokamak Fusion Test Reactor (TFTR) and The Next Step (TNS). The test facility can simulate a complete beam line injection system and can provide a wide range of experimental operating conditions. Herein is offered a general description of the facility's capabilities and a discussion of present system performance.
Date:
January 1, 1977
Creator:
Gardner, W.L.; Kim, J.; Menon, M.M. & Schilling, G.
System:
The UNT Digital Library
Search for W-prime boson production in the top quark decay channel
We present a search for the production of a new heavy gauge boson W' that decays to a top quark and a bottom quark. We have analyzed 230 pb{sup -1} of data collected with the D0 detector at the Fermilab Tevatron collider at a center-of-mass energy of 1.96 TeV. No significant excess of events is found in any region of the final state invariant mass distribution. We set upper limits on the production cross section of W bosons at the 95% confidence level for several different W' boson masses. We exclude masses below 610 GeV for a W' boson with standard-model-like couplings, below 630 GeV for a W' boson with right-handed couplings that is allowed to decay to both leptons and quarks, and below 670 GeV for a W' boson with right-handed couplings that is only allowed to decay to quarks.
Date:
July 1, 2006
Creator:
Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
System:
The UNT Digital Library
Pulsed laser stereo photography of electrically exploded bridges
A technique is described for obtaining short exposure (approximately 8 ns) high resolution photomicrographs of electrically exploded bridges using a pulsed laser for bridge illumination and band-pass filters to eliminate the intense self light. Two cameras are described, one for a small field of view (approximately 1 mm) and one for a relatively large field of view (approximately 20 mm). A carbon disulfide cell and a fiber-optic light guide are used to essentially eliminate speckle, which normally limits the resolution of laser photographs of diffuse surfaces. A series of photomicrographs showing the detailed burst characteristics of both flat and round bridges are shown.
Date:
January 1, 1976
Creator:
Seitz, W. L. & Gardner, S. D.
System:
The UNT Digital Library
Search for right-handed W bosons in top quark decay
None
Date:
May 1, 2005
Creator:
Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
System:
The UNT Digital Library
Ion exchange properties of novel hydrous metal oxide materials
Hydrous metal oxide (HMO) materials are inorganic ion exchangers which have many desirable characteristics for catalyst support applications, including high cation exchange capacity, anion exchange capability, high surface area, ease of adjustment of acidity and basicity, bulk or thin film preparation, and similar chemistry for preparation of various transition metal oxides. Cation exchange capacity is engineered into these materials through the uniform incorporation of alkali cations via manipulation of alkoxide chemistry. Specific examples of the effects of Na stoichiometry and the addition of SiO{sub 2} to hydrous titanium oxide (HTO) on ion exchange behavior will be given. Acid titration and cationic metal precursor complex exchange will be used to characterize the ion exchange behavior of these novel materials.
Date:
December 31, 1996
Creator:
Gardner, T.J. & McLaughlin, L.I.
System:
The UNT Digital Library
A Search for anomalous heavy-flavor quark production in association with W bosons
None
Date:
November 1, 2004
Creator:
Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
System:
The UNT Digital Library
Comparison of the folded stripline and stacked stripline concepts to the folded waveguide launcher
Two new concepts are being developed as possible upgrades to the folded waveguide launcher. The folded stripline is a folded waveguide with an additional conductor positioned inside. The term stripline refers to the resemblance of the design to microwave microstrip line. The conductor provides support for TEM mode propagation, which eliminates cutoff and the nonlinear frequency dependence of the waveguide impedance and phase velocity. A natural extension to the folded stripline is the stacked stripline, which comprises several stacked, independent TEM waveguides. Initial measurements indicate that both concepts have better magnetic flux coupling than the folded waveguide.
Date:
December 31, 1993
Creator:
Gardner, W. L.; Caughman, J. B. O.; Hoffman, D. J. & Probert, P. H.
System:
The UNT Digital Library
Judge Thomas H. Doyle
Article honors Judge Thomas H. Doyle through detailing his life and accomplishments while serving within the state of Oklahoma.
Date:
Summer 1949
Creator:
Evans, Charles
System:
The Gateway to Oklahoma History
The March of the First Dragoons from Jefferson Barracks to fort Gibson in 1833-1834
Article discusses the activation of the first United States Dragoons and their arduous march from Jefferson Barracks to Fort Gibson in 1833 to 1834. Hamilton Gardner examines journal records of the officers, and correspondence that documented the journey, to create a clearer picture of the experience.
Date:
Spring 1953
Creator:
Gardner, Hamilton
System:
The Gateway to Oklahoma History
Looking Ahead - Biofuels, H2, & Vehicles: 21st Industry Growth Forum
This presentation on the future of biofuels, hydrogen, and hybrid vehicles was presented at NREL's 21st Industry Growth Forum in Denver, Colorado, on October 28, 2008.
Date:
October 28, 2008
Creator:
Gardner, D.
System:
The UNT Digital Library
Indium donor complexes with cation vacancies in CdTe and ZnSe
Very dilute (10{sub 12} cm{sup {minus}3}) indium donors in CdTe and ZnSe powders and in CdTe single crystals were investigated using {sup 111}In Perturbed angular correlation spectroscopy. Most indium atoms are in uncomplexed sites but can form weakly-bound complexes with native defects in very defective material. The only complex observed in CdTe is an indium-Cd vacancy pair. The CdTe in which these pairs occur is apparently n-type, most Cd vacancies are free and doubly-charged, and the binding energy with indium is 0.15 eV. In ZnSe, indium can pair with a Zn vacancy or with some other presently unidentified defect. These complexes form in ZnSe containing large concentrations of both free Zn vacancies and complexes of Zn vacancies with other defects. In CdTe, the pair formation equilibration time constant is two days at 15C,an implication that Cd vacancies are mobile at room temperature. Lattice relaxation around a Cd vacancy in CdTe was probed by single crystal PAC experiments.
Date:
November 1, 1993
Creator:
Griffith, J. W.; Lundquist, R.; Platzer, R.; Gardner, J. A.; Karczewski, G. & Furdyna, J. K.
System:
The UNT Digital Library
One Hundred Years Ago in the Region of Tulsa
Article reports on the conditions of the Indian Territory as told by surveyors a hundred years from the date this article was published. These surveyors were tasked with determining whether the region was fit enough to relocate the Creek tribes to after their removal from the east.
Date:
Summer 1933
Creator:
Gardner, James H.
System:
The Gateway to Oklahoma History
Calculational tools for the evaluation of nuclear cross-section and spectra data
A technique based on discrete energy levels rather than energy level densities is presented for nuclear reaction calculations. The validity of the technique is demonstrated via theoretical and experimental agreement for cross sections, isomer-ratios and gamma-ray strength functions. 50 refs., 7 figs. (WRF)
Date:
May 7, 1985
Creator:
Gardner, M.A.
System:
The UNT Digital Library
Recent developments in nuclear reaction theories and calculations
A brief review is given of some recent developments in the fields of optical model potentials; level densities; and statistical model, precompound, and direct reaction codes and calculations. Significant developments have occurred in all of these fields since the 1977 Conference on Neutron Cross Sections, which will greatly enhance the ability to calculate high-energy neutron-induced reaction cross sections in the next few years. 11 figures, 3 tables.
Date:
May 5, 1980
Creator:
Gardner, D. G.
System:
The UNT Digital Library