Generalization of the ERIT principle and method. (open access)

Generalization of the ERIT principle and method.

The paper describes the generalization of the method to produce secondary particles with a low-energy and low-intensity primary beam circulating in a Storage Ring with the Emittance-Recovery by Internal-Target (ERIT).
Date: November 4, 2007
Creator: Ruggiero, A. G.
System: The UNT Digital Library
Rapid Undercooling and Refreeze in Laser-Shock-Melted Bi(Zn) (open access)

Rapid Undercooling and Refreeze in Laser-Shock-Melted Bi(Zn)

We completed experiments in which we used a high-power laser to shock-melt a Bi(Zn) alloy and refreeze it in the shock release wave. We recovered the samples post shot for microscopic analysis and compared our results with the results from similar prior experiments with pure Bi. The targets in both sets of experiments were four-layer targets composed of BK7 glass, Al, the elemental Bi or Bi(Zn) alloy, and a transparent diagnostic window. There is conductive heating of the Bi through the Al layer from the hot plasma at the Al/BK7 boundary that depends on the Al thickness. Since the Bi(Zn) targets had a much thicker Al layer than did the Bi targets, the two sets of targets had somewhat different thermal histories even though they were driven to the same pressure. In this presentation we compare the resolidified Bi(Zn) microstructure to that of the Bi, accounting for the different thermal histories.
Date: November 4, 2005
Creator: Jankowski, Alan Frederic; Colvin, J.; Reed, B. & Kumar, M.
System: The UNT Digital Library
Age validation of canary rockfish (Sebastes pinniger) using two independent otolith techniques: lead-radium and bomb radiocarbon dating. (open access)

Age validation of canary rockfish (Sebastes pinniger) using two independent otolith techniques: lead-radium and bomb radiocarbon dating.

Canary rockfish (Sebastes pinniger) have long been an important part of recreational and commercial rockfish fishing from southeast Alaska to southern California, but localized stock abundances have declined considerably. Based on age estimates from otoliths and other structures, lifespan estimates vary from about 20 years to over 80 years. For the purpose of monitoring stocks, age composition is routinely estimated by counting growth zones in otoliths; however, age estimation procedures and lifespan estimates remain largely unvalidated. Typical age validation techniques have limited application for canary rockfish because they are deep dwelling and may be long lived. In this study, the unaged otolith of the pair from fish aged at the Department of Fisheries and Oceans Canada was used in one of two age validation techniques: (1) lead-radium dating and (2) bomb radiocarbon ({sup 14}C) dating. Age estimate accuracy and the validity of age estimation procedures were validated based on the results from each technique. Lead-radium dating proved successful in determining a minimum estimate of lifespan was 53 years and provided support for age estimation procedures up to about 50-60 years. These findings were further supported by {Delta}{sup 14}C data, which indicated a minimum estimate of lifespan was 44 {+-} 3 …
Date: November 4, 2007
Creator: Andrews, A H; Kerr, L A; Cailliet, G M; Brown, T A; Lundstrom, C C & Stanley, R D
System: The UNT Digital Library
Coherent States and Spontaneous Symmetry Breaking in Light Front Scalar Field Theory (open access)

Coherent States and Spontaneous Symmetry Breaking in Light Front Scalar Field Theory

None
Date: November 4, 2005
Creator: Vary, J P; Chakrabarti, D; Harindranath, A; Lloyd, R; Martinovic, L & Spence, J R
System: The UNT Digital Library
FutureGen: Pathway to Near-Zero Emissions and Sustainable Energy (open access)

FutureGen: Pathway to Near-Zero Emissions and Sustainable Energy

This presentation will highlight the U.S. Department of Energy’s (DOE) FutureGen project − a $1 billion government-industry partnership to design, build, and operate a near-zero emissions coal-fueled power plant. The lead organization for the FutureGen initiative is the National Energy Technology Laboratory (NETL), a multi-purpose laboratory operated by the U.S. DOE’s Office of Fossil Energy. NETL has a mission to conduct R&D from fundamental science to technology demonstration for resolving the environmental, supply, and reliability constraints of producing and using fossil energy resources. The commercial-scale FutureGen R&D facility is a pathway toward future fossil-energy power plants that will produce hydrogen and electricity while nearly eliminating emissions, including carbon dioxide. The 275-megawatt FutureGen plant will initiate operations around 2012 and employ advanced coal gasification technology integrated with combined cycle electricity generation, hydrogen production, and carbon capture and sequestration. Low carbon emissions would be achieved by integrating CO2 capture and sequestration operations with the power plant.
Date: November 4, 2007
Creator: Zitney, S. E. & Sarkus, T. A
System: The UNT Digital Library
Surface and bulk contribution to Cu(111) quantum efficiency (open access)

Surface and bulk contribution to Cu(111) quantum efficiency

The quantum efficiency (QE) of Cu(111) is measured for different impinging light angles with photon energies just above the work function. We observe that the vectorial photoelectric effect, an enhancement of the QE due to illumination with light with an electric vector perpendicular to the sample surface, is stronger in the more surface sensitive regime. This can be explained by a contribution to photoemission due to the variation in the electromagnetic potential at the surface. The contributions of bulk and surface electrons can then be determined.
Date: November 4, 2008
Creator: Pedersoli, Emanuele; Greaves, Corin Michael Ricardo; Wan, Weishi; Coleman-Smith, Christopher; Padmore, Howard A.; Pagliara, Stefania et al.
System: The UNT Digital Library
Coordination of 1,4-Diazabutadiene Ligands to Decamethylytterbocene: Additional Examples of Spin Coupling in Ytterbocene Complexes (open access)

Coordination of 1,4-Diazabutadiene Ligands to Decamethylytterbocene: Additional Examples of Spin Coupling in Ytterbocene Complexes

The paramagnetic 1:1 coordination complexes of (C5Me5)2Yb with a series of diazabutadiene ligands, RN=C(R')C(R')=NR, where R= CMe3, CHMe2, adamantyl, p-tolyl, p-anisyl, and mesityl when R'=H, and R= p-anisyl when R'= Me, have been prepared. The complexes are paramagnetic, but their magnetic moments are less than expected for the two uncoupled spin carriers, (C5Me5)2Yb(III, 4f13) and the diazabutadiene radical anions (S=1/2), which implies exchange coupling between the spins. The variable temperature 1H NMR spectra show that rotation about the R-N bond is hindered and these barriers are estimated. The barriers are largely determined by steric effects but electronic effects are not unimportant.
Date: November 4, 2006
Creator: Andersen, Richard; Walter, Marc D.; Berg, David J. & Andersen, Richard A.
System: The UNT Digital Library
Science and Technology in Support of U.S. Policy in Central Asia (open access)

Science and Technology in Support of U.S. Policy in Central Asia

The current war with Iraq, international interventions in Afghanistan, and the continuous and seemingly insolvable problems in the Middle East emphasize the importance of supporting stable, healthy countries throughout the Middle East and South and Central Asia. The political alliances and foreign aid promulgated by the Cold War have been seriously strained, creating a more uncertain and unstable international environment. We must stay engaged with this part of the world. New partnerships must be forged. Central Asia represents a mix of political systems - from totalitarian rule to nascent democracy; of economic resources from natural to human; and of cultures from ancient to modern - making it of strategic importance to U. S. national and economic security. The U.S. must remain committed and proactively engaged in the region to promote open and democratic societies attractive to outside investment and to prevent the proliferation of weapons of mass destruction and extremist groups. The U.S is admired for its science and technology and its flexibility in innovation and applying S&T to solve problems. The inherent value that S&T can contribute to advancing U.S. policy goals is the underlying assumption of this report. Science and technology and their applications have much to contribute …
Date: November 4, 2003
Creator: Knapp, R B
System: The UNT Digital Library
Ground motion modeling of Hayward fault scenario earthquakes II:Simulation of long-period and broadband ground motions (open access)

Ground motion modeling of Hayward fault scenario earthquakes II:Simulation of long-period and broadband ground motions

We simulate long-period (T > 1.0-2.0 s) and broadband (T > 0.1 s) ground motions for 39 scenarios earthquakes (Mw 6.7-7.2) involving the Hayward, Calaveras, and Rodgers Creek faults. For rupture on the Hayward fault we consider the effects of creep on coseismic slip using two different approaches, both of which reduce the ground motions compared with neglecting the influence of creep. Nevertheless, the scenario earthquakes generate strong shaking throughout the San Francisco Bay area with about 50% of the urban area experiencing MMI VII or greater for the magnitude 7.0 scenario events. Long-period simulations of the 2007 Mw 4.18 Oakland and 2007 Mw 4.5 Alum Rock earthquakes show that the USGS Bay Area Velocity Model version 08.3.0 permits simulation of the amplitude and duration of shaking throughout the San Francisco Bay area, with the greatest accuracy in the Santa Clara Valley (San Jose area). The ground motions exhibit a strong sensitivity to the rupture length (or magnitude), hypocenter (or rupture directivity), and slip distribution. The ground motions display a much weaker sensitivity to the rise time and rupture speed. Peak velocities, peak accelerations, and spectral accelerations from the synthetic broadband ground motions are, on average, slightly higher than the …
Date: November 4, 2009
Creator: Aagaard, B T; Graves, R W; Rodgers, A; Brocher, T M; Simpson, R W; Dreger, D et al.
System: The UNT Digital Library
Corrosion Behavior of Alloy 22 in Chloride Solutions Containing Organic Acids (open access)

Corrosion Behavior of Alloy 22 in Chloride Solutions Containing Organic Acids

Alloy 22 (N06022) is a nickel based alloy containing alloying elements such as chromium, molybdenum and tungsten. It is highly corrosion resistant both under reducing and under oxidizing conditions. Electrochemical studies such as electrochemical impedance spectroscopy (EIS) were performed to determine the corrosion behavior of Alloy 22 in 1M NaCl solutions at various pH values from acidic to neutral at 90 C. Tests were also carried out in NaCl solutions containing oxalic acid or acetic acid. It is shown that the corrosion rate of Alloy 22 was higher in a solution containing oxalic acid than in a solution of the same pH acidified with HCl. Acetic acid was not corrosive to Alloy 22. The corrosivity of oxalic acid was attributed to its capacity to form stable complex species with metallic cations from Alloy 22.
Date: November 4, 2005
Creator: Carranza, R M; Giordano, C M; Rodr?guez, M A & Rebak, R B
System: The UNT Digital Library
Interaction of Nocturnal Low-Level Jets with Urban Geometries as seen in Joint URBAN 2003 Data (open access)

Interaction of Nocturnal Low-Level Jets with Urban Geometries as seen in Joint URBAN 2003 Data

None
Date: November 4, 2005
Creator: Lundquist, J K & Mirocha, J D
System: The UNT Digital Library
Magnetization reversal behaviour of nanogranular CoCrPt alloy thinfilms studied with magnetic transmission X-ray microscopy (open access)

Magnetization reversal behaviour of nanogranular CoCrPt alloy thinfilms studied with magnetic transmission X-ray microscopy

The angular dependence of dissociative electron attachment (DEA) to polyatomic targets is formulated in the local complex potential model, under the assumption that the axial recoil approximation describes the dissociation dynamics. An additional approximation, which is found to be valid in the case of H{sub 2}O but not in the case of H{sub 2}S, makes it possible to describe the angular dependence of DEA solely from an analysis of the fixed-nuclei entrance amplitude, without carrying out nuclear dynamics calculations. For H{sub 2}S, the final-vibrational-state-specific angular dependence of DEA is obtained by incorporating the variation of the angular dependence of the entrance amplitude with nuclear geometry into the nuclear dynamics. Scattering calculations using the complex Kohn method and, for H{sub 2}S, full quantum calculations of the nuclear dynamics using the Multi-Configuration Time-Dependent Hartree method, are performed.
Date: November 4, 2004
Creator: Fischer, P.; Im, M.-Y.; Eimuller, T.; Schutz, G. & Shin, S.-C.
System: The UNT Digital Library
Minijet Deformation and Charge-independent Two-particleCorrelations on Momentum Subspace (eta,phi) In Au-Au Collisions atsqrt(sNN) = 130 GeV (open access)

Minijet Deformation and Charge-independent Two-particleCorrelations on Momentum Subspace (eta,phi) In Au-Au Collisions atsqrt(sNN) = 130 GeV

We present first measurements of charge-independent correlations on momentum-space difference variables {eta}{sub 1}-{eta}{sub 2} (pseudorapidity) and {phi}{sub 1}-{phi}{sub 2} (azimuth) for charged primary hadrons with transverse momentum within 0.15 {le} p{sub t} {le} 2 GeV/c and |{eta}| {le} 1.3 from Au-Au collisions at {radical}s{sub NN} = 130 GeV. We observe strong charge-independent correlations associated with minijets and elliptic flow. The width of the minijet peak on {eta}{sub 1}-{eta}{sub 2} increases by a factor 2.3 from peripheral to central collisions, suggesting strong coupling of partons to a longitudinally-expanding colored medium. New methods of jet analysis introduced here reveal nonperturbative medium effects in heavy ion collisions.
Date: November 4, 2004
Creator: Adams, J.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D.; Arkhipkin, D. et al.
System: The UNT Digital Library
The South Pole Telescope (open access)

The South Pole Telescope

A new 10 meter diameter telescope is being constructed for deployment at the NSF South Pole research station. The telescope is designed for conducting large-area millimeter and sub-millimeter wave surveys of faint, low contrast emission, as required to map primary and secondary anisotropies in the cosmic microwave background. To achieve the required sensitivity and resolution, the telescope design employs an off-axis primary with a 10 m diameter clear aperture. The full aperture and the associated optics will have a combined surface accuracy of better than 20 microns rms to allow precision operation in the submillimeter atmospheric windows. The telescope will be surrounded with a large reflecting ground screen to reduce sensitivity to thermal emission from the ground and local interference. The optics of the telescope will support a square degree field of view at 2mm wavelength and will feed a new 1000-element micro-lithographed planar bolometric array with superconducting transition-edge sensors and frequency-multiplexed readouts. The first key project will be to conduct a survey over 4000 degrees for galaxy clusters using the Sunyaev-Zeldovich Effect. This survey should find many thousands of clusters with a mass selection criteria that is remarkably uniform with redshift. Armed with redshifts obtained from optical and infrared …
Date: November 4, 2004
Creator: Ruhl, J. E.; Ade, P. A. R.; Carlstrom, J. E.; Cho, H. M.; Crawford, T.; Dobbs, M. et al.
System: The UNT Digital Library
Processing Tritiated Water at the Savannah Rivver Site: A Production Scale Demonstration (open access)

Processing Tritiated Water at the Savannah Rivver Site: A Production Scale Demonstration

The Palladium Membrane Reactor (PMR) process was installed in the Tritium Facilities at the Savannah River Site to perform a production-scale demonstration for the recovery of tritium from tritiated water adsorbed on molecular sieve (zeolite). Unlike the current recovery process that utilizes magnesium, the PMR offers a means to process tritiated water in a more cost effective and environmentally friendly manner. The design and installation of the large-scale PMR process was part of a collaborative effort between the Savannah River Site and Los Alamos National Laboratory. The PMR process operated at the Savannah River Site between May 2001 and April 2003. During the initial phase of operation the PMR processed thirty-four kilograms of tritiated water from the Princeton Plasma Physics Laboratory. The water was processed in fifteen separate batches to yield approximately 34,400 liters (STP) of hydrogen isotopes. Each batch consisted of round-the-clock operations for approximately nine days. In April 2003 the reactor's palladium-silver membrane ruptured resulting in the shutdown of the PMR process. Reactor performance, process performance and operating experiences have been evaluated and documented. A performance comparison between PMR and current magnesium process is also documented.
Date: November 4, 2004
Creator: Sessions, K
System: The UNT Digital Library
Branching Fraction And Direct CP Violating Asymmetries in Charmless Twobody B Decays at BaBar (open access)

Branching Fraction And Direct CP Violating Asymmetries in Charmless Twobody B Decays at BaBar

We present preliminary measurements of branching fractions and direct CP violating asymmetries in charmless two-body B decays, obtained with the BABAR detector using a sample of 227M {Upsilon}(4S) {yields} B{bar B} decays. We report the first observation of B{sup 0} {yields} K{sup 0}{bar K}{sup 0} and the first observation of direct CP violation in B{sup 0} {yields} K{sup +}{pi}{sup -} decays.
Date: November 4, 2005
Creator: Hulsbergen, W.D.
System: The UNT Digital Library
Nucleosynthesis in Early Supernova Winds II: The Role of Neutrinos (open access)

Nucleosynthesis in Early Supernova Winds II: The Role of Neutrinos

One of the outstanding unsolved riddles of nuclear astrophysics is the origin of the so called ''p-process'' nuclei from A = 92 to 126. Both the lighter and heavier p-process nuclei are adequately produced in the neon and oxygen shells of ordinary Type II supernovae, but the origin of these intermediate isotopes, especially {sup 92,94}Mo and {sup 96,98}Ru, has long been mysterious. Here we explore the production of these nuclei in the neutrino-driven wind from a young neutron star. We consider such early times that the wind still contains a proton excess because the rates for {nu}{sub e} and positron captures on neutrons are faster than those for the inverse captures on protons. Following a suggestion by Froehlich et al. (2005), they also include the possibility that, in addition to the protons, {alpha}-particles, and heavy seed, a small flux of neutrons is maintained by the reaction p({bar {nu}}{sub e}, e{sup +})n. This flux of neutrons is critical in bridging the long waiting points along the path of the rp-process by (n,p) and (n,{gamma}) reactions. Using the unmodified ejecta histories from a recent two-dimensional supernova model by Janka, Buras, and Rampp (2003), they find synthesis of p-rich nuclei up to {sup …
Date: November 4, 2005
Creator: Pruet, J; Hoffman, R; Woosley, S; Janka, H & Buras, R
System: The UNT Digital Library
Conference papers/proceedings (open access)

Conference papers/proceedings

None
Date: November 4, 2004
Creator: Fuks, Dr. Zvi
System: The UNT Digital Library
SYNCHROTRON RADIATION MONITOR FOR NSLS BOOSTER. (open access)

SYNCHROTRON RADIATION MONITOR FOR NSLS BOOSTER.

NSLS booster diagnostics consisted of tune measurement system, system for turn-by-turn measurement on the electron beam, and beam intensity monitor, which is not absolutely calibrated. We present design and implementation of synchrotron light monitor for the booster, which expands diagnostics capabilities. The system allows to measure an orbit, beam sizes and coupling of the electron beam along the ramp.
Date: November 4, 2005
Creator: PINAYEV, I. & SHAFTAN, T.
System: The UNT Digital Library
The Advanced Light Source Upgrade (open access)

The Advanced Light Source Upgrade

The ALS, a third-generation synchrotron light source at Berkeley Lab, has been operating for almost a decade and is generating forefront science by exploiting the high brightness of a third-generation source in three areas: (1) high resolving power for spectroscopy; (2) high spatial resolution for microscopy and spectromicroscopy; and (3) high coherence for experiments such as speckle. However, the ALS was one of the first third-generation machines to be designed, and accelerator and insertion-device technology have significantly changed since its conception. As a result, its performance will inevitably be outstripped by newer, more advanced sources. To remain competitive and then set a new standard, the performance of the ALS, in particular its brightness, must be enhanced. Substantial improvements in brightness and current have always been feasible in principle, but they incur the penalty of a much reduced lifetime, which is totally unacceptable to our users. Significant brightness improvements can be realized in the core soft x-ray region by going to top-off operation, where injection would be quasi-continuous and the lifetime objections disappear. In top-off mode with higher average current, a reduced vertical emittance and beta function, and small-gap permanent-magnet or superconducting insertion devices, one to two orders of magnitude improvement …
Date: November 4, 2003
Creator: Chemla, Daniel S.; Feinberg, Benjamin; Hussain, Zahid; Krebs, Gary F.; Padmore, Howard A.; Robin, David S. et al.
System: The UNT Digital Library
Application of adaptive mesh refinement to particle-in-cell simulations of plasmas and beams (open access)

Application of adaptive mesh refinement to particle-in-cell simulations of plasmas and beams

Plasma simulations are often rendered challenging by the disparity of scales in time and in space which must be resolved. When these disparities are in distinctive zones of the simulation domain, a method which has proven to be effective in other areas (e.g. fluid dynamics simulations) is the mesh refinement technique. We briefly discuss the challenges posed by coupling this technique with plasma Particle-In-Cell simulations, and present examples of application in Heavy Ion Fusion and related fields which illustrate the effectiveness of the approach. We also report on the status of a collaboration under way at Lawrence Berkeley National Laboratory between the Applied Numerical Algorithms Group (ANAG) and the Heavy Ion Fusion group to upgrade ANAG's mesh refinement library Chombo to include the tools needed by Particle-In-Cell simulation codes.
Date: November 4, 2003
Creator: Vay, J. L.; Colella, P.; Kwan, J. W.; McCorquodale, P.; Serafini, D. B.; Friedman, A. et al.
System: The UNT Digital Library
Mechanisms of Strontium and Uranium Removal from High-Level Radioactive Waste Simulant Solutions by the Sorbent Monosodium Titanate (open access)

Mechanisms of Strontium and Uranium Removal from High-Level Radioactive Waste Simulant Solutions by the Sorbent Monosodium Titanate

High-Level Waste (HLW) is a waste associated with the dissolution of spent nuclear fuel for the recovery of weapons-grade material. It is the priority problem for the U.S. Department of Energy's Environmental Management Program. Current HLW treatment processes at the Savannah River Site (Aiken, SC) include the use of monosodium titanate. The local structural speciation of sorbed U varied with loading but not for Sr. Sorbed Sr exhibited specific adsorption as partially-hydrated species whereas sorbed U exhibited specific adsorption as monomeric and dimeric U(VI)-carbonate complexes. Sorption proved site specific. These differences in site specificity and sorption mechanism may account for the difficulties associated with predicting Sr and U loading and removal kinetics using MST.
Date: November 4, 2003
Creator: Duff, M.C.
System: The UNT Digital Library
Top quark and electroweak results from CDF (open access)

Top quark and electroweak results from CDF

In 2001 the Tevatron run II began, after a five year period of significant upgrade of the accelerator itself and of the experiments CDF and D0. After a detector commissioning run, the CDF experiment is now taking high quality data with all subsystems functional. We report in this talk the first preliminary CDF results on top quark and W/Z boson properties, based on run II data. The top quark, discovered in 1995 at the Tevatron, has proven to be a very interesting particle. Its properties allow to perform stringent tests of the Standard Model (SM) and to search for new physics through a deviation from SM predictions. We give here some expectations of what Tevatron run II will ultimately provide to our understanding of matter.
Date: November 4, 2003
Creator: Leone, Sandra
System: The UNT Digital Library
Conceptual design of a compact positron tomograph for prostateimaging (open access)

Conceptual design of a compact positron tomograph for prostateimaging

We present a conceptual design of a compact positron tomograph for prostate imaging using a pair of external curved detector banks, one placed above and one below the patient. The lower detector bank is fixed below the patient bed, and the top bank adjusts vertically for maximum sensitivity and patient access. Each bank is composed of 40conventional block detectors, forming two arcs (44 cm minor, 60 cm major axis) that are tilted to minimize attenuation and positioned as close as possible to the patient to improve sensitivity. The individual detectors are angled to point towards the prostate to minimize resolution degradation in that region. Inter-plane septa extend 5 cm beyond the scintillator crystals to reduce random and scatter backgrounds. A patient is not fully encircled by detector rings in order to minimize cost,causing incomplete sampling due to the side gaps. Monte Carlo simulation (including random and scatter) demonstrates the feasibility of detecting a spherical tumor of 2.5 cm diameter with a tumor to background ratio of2:1, utilizing the number of events that should be achievable with a6-minute scan after a 10 mCi injection (e.g., carbon-11 choline or fluorine-18 fluorocholine).
Date: November 4, 2000
Creator: Huber, J. S.; Derenzo, S. E.; Qi, J.; Moses, W. W.; Huesman, R. H. & Budinger, T. F.
System: The UNT Digital Library