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Operation of a Free-Electron Laser from the Extreme Ultraviolet to the Water Window

Description: We report results on the performance of a free-electron laser operating at a wavelength of 13.7 nm where unprecedented peak and average powers for a coherent extreme-ultraviolet radiation source have been measured. In the saturation regime, the peak energy approached 170 {micro}J for individual pulses, and the average energy per pulse reached 70 {micro}J. The pulse duration was in the region of 10 fs, and peak powers of 10 GW were achieved. At a pulse repetition frequency of 700 pulses per seco… more
Date: December 17, 2007
Creator: Ackermann, W.; Asova, G.; Ayvazyan, V.; Azima, A.; Baboi, N.; Bahr, J. et al.
Partner: UNT Libraries Government Documents Department
open access

Water, law, science

Description: In a world with water resources severely impacted bytechnology, science must actively contribute to water law. To this end,this paper is an earth scientist s attempt to comprehend essentialelements of water law, and to examine their connections to science.Science and law share a common logical framework of starting with apriori prescribed tenets, and drawing consistent inferences. In science,observationally established physical laws constitute the tenets, while inlaw, they stem from social valu… more
Date: October 17, 2007
Creator: Narasimhan, T.N.
Partner: UNT Libraries Government Documents Department
open access

CAMS/LLNL Ion Source Efficiency Revisited

Description: No Description Available.
Date: April 17, 2007
Creator: Fallon, S. J.; Guilderson, T. P. & Brown, T. A.
Partner: UNT Libraries Government Documents Department
open access

137Cs Inter-Plant Concentration Ratios Provide a Predictive Tool for Coral Atolls with Distinct Benefits Over Transfer Factors

Description: Inter-plant concentration ratios (IPCR), [Bq g{sup -1} {sup 137}Cs in coral atoll tree food-crops/Bq g{sup -1} {sup 137}Cs in leaves of native plant species whose roots share a common soil volume], can replace transfer factors (TF) to predict {sup 137}Cs concentration in tree food-crops in a contaminated area with an aged source term. The IPCR strategy has significant benefits relative to TF strategy for such purposes in the atoll ecosystem. IPCR strategy applied to specific assessments takes a… more
Date: July 17, 2007
Creator: Robison, W L; Hamilton, T F; Bogen, K; Corado, C L & Kehl, S R
Partner: UNT Libraries Government Documents Department
open access

In-situ probing of lattice response in shock compressed materials using x-ray diffraction

Description: Lattice level measurements of material response under extreme conditions are required to build a phenomenological understanding of the shock response of solids. We have successfully used laser produced plasma x-ray sources coincident with laser driven shock waves to make in-situ measurements of the lattice response during shock compression for both single crystal and polycrystalline materials. Using a detailed analysis of shocked single crystal iron which has undergone the {alpha} - {var_epsilo… more
Date: July 17, 2007
Creator: Hawreliak, J.; Butterfield, M.; Davies, H.; El-Dasher, B.; Higginbotham, A.; Kalantar, D. et al.
Partner: UNT Libraries Government Documents Department
open access

SOFTWARE QUALITY ASSURANCE FOR EMERGENCY RESPONSE CONSEQUENCE ASSESSMENT MODELS AT DOE'S SAVANNAH RIVER SITE

Description: The Savannah River National Laboratory's (SRNL) Atmospheric Technologies Group develops, maintains, and operates computer-based software applications for use in emergency response consequence assessment at DOE's Savannah River Site. These applications range from straightforward, stand-alone Gaussian dispersion models run with simple meteorological input to complex computational software systems with supporting scripts that simulate highly dynamic atmospheric processes. A software quality assura… more
Date: December 17, 2007
Creator: Hunter, C
Partner: UNT Libraries Government Documents Department
open access

Counting constituents in molecular complexes by fluorescence photon antibunching

Description: Modern single molecule fluorescence microscopy offers new, highly quantitative ways of studying the systems biology of cells while keeping the cells healthy and alive in their natural environment. In this context, a quantum optical technique, photon antibunching, has found a small niche in the continuously growing applications of single molecule techniques to small molecular complexes. Here, we review some of the most recent applications of photon antibunching in biophotonics, and we provide a … more
Date: April 17, 2007
Creator: Fore, S; Laurence, T; Hollars, C & Huser, T
Partner: UNT Libraries Government Documents Department
open access

Stable SUSY breaking model with O(10) eV gravitino from combined D-term gauge mediation and U(1)' mediation

Description: We show a calculable example of stable supersymmetry (SUSY) breaking modelswith O(10) eV gravitino mass based on the combination of D-term gauge mediationand U(1)' mediation. A potential problem of the negative mass squared for theSUSY standard model (SSM) sfermions in the D-term gauge mediation is solvedby the contribution from the U(1)' mediation. On the other hand, the splittingbetween the SSM gauginos and sfermions in the U(1)' mediation iscircumvented bythe contributions from t… more
Date: December 17, 2007
Creator: Nakayama, Yu & Nakayama, Yu
Partner: UNT Libraries Government Documents Department
open access

Fragmentation Cross Sections of 290 and 400 MeV/nucleon 12C Beamson Elemental Targets

Description: Charge-changing and fragment production cross sections at 0circ have been obtained for interactions of 290 MeV/nucleon and 400MeV/nucleon carbon beams with C, CH2, Al, Cu, Sn, and Pb targets. Thesebeams are relevant to cancer therapy, space radiation, and the productionof radioactive beams. We compare to previously published results using Cand CH2 targets at similar beam energies. Due to ambiguities arising fromthe presence of multiple fragments on many events, previous publicationshave reporte… more
Date: March 17, 2007
Creator: Zeitlin, C.; Guetersloh, S.; Heilbronn, L.; Miller, J.; Fukumura,A.; Iwata, Y. et al.
Partner: UNT Libraries Government Documents Department
open access

A celestial gamma-ray foreground due to the albedo of small solar system bodies and a remote probe of the interstellar cosmic ray spectrum

Description: We calculate the {gamma}-ray albedo flux from cosmic-ray (CR) interactions with the solid rock and ice in Main Belt asteroids and Kuiper Belt objects (KBOs) using the Moon as a template. We show that the {gamma}-ray albedo for the Main Belt and Kuiper Belt strongly depends on the small-body mass spectrum of each system and may be detectable by the forthcoming Gamma Ray Large Area Space Telescope (GLAST). The orbits of the Main Belt asteroids and KBOs are distributed near the ecliptic, which pas… more
Date: December 17, 2007
Creator: Moskalenko, Igor V.; Porter, Troy A.; Digel, Seth W.; Michelson, Peter F. & Ormes, Jonathan F.
Partner: UNT Libraries Government Documents Department
open access

A stable finite difference method for the elastic wave equation on complex geometries with free surfaces

Description: The isotropic elastic wave equation governs the propagation of seismic waves caused by earthquakes and other seismic events. It also governs the propagation of waves in solid material structures and devices, such as gas pipes, wave guides, railroad rails and disc brakes. In the vast majority of wave propagation problems arising in seismology and solid mechanics there are free surfaces. These free surfaces have, in general, complicated shapes and are rarely flat. Another feature, characterizing … more
Date: December 17, 2007
Creator: Appelo, D & Petersson, N A
Partner: UNT Libraries Government Documents Department
open access

High-Power Laser Pulse Recirculation for Inverse Compton Scattering-Produced Gamma-Rays

Description: Inverse Compton scattering of high-power laser pulses on relativistic electron bunches represents an attractive method for high-brightness, quasi-monoenergetic {gamma}-ray production. The efficiency of {gamma}-ray generation via inverse Compton scattering is severely constrained by the small Thomson scattering cross section. Furthermore, repetition rates of high-energy short-pulse lasers are poorly matched with those available from electron accelerators, resulting in low repetition rates for ge… more
Date: April 17, 2007
Creator: Jovanovic, I; Shverdin, M; Gibson, D & Brown, C
Partner: UNT Libraries Government Documents Department
open access

Milestones in EBIT Spectroscopy and Why it Almost Didn't Work

Description: The EBIT spectroscopy that now seems routine would not be possible without considerable good luck in several areas of EBIT technology. Among these are x-ray background, ion cooling, neutral gas density, and electron current density and energy control. A favourable outcome in these areas has enabled clean x-ray spectra, sufficient intensity for high resolution spectroscopy, production of very high charge states, and a remarkable variety of spectroscopic measurements. During construction of the f… more
Date: July 17, 2007
Creator: Marrs, R E
Partner: UNT Libraries Government Documents Department
open access

Displacement Current and Surface Flashover

Description: High-voltage vacuum insulator failure is generally due to surface flashover rather than insulator bulk breakdown. Vacuum surface flashover is widely believed to be initiated by a secondary electron emission avalanche along the vacuum-insulator interface. This process requires a physical mechanism to cause secondary electrons emitted from the insulator surface to return to that surface. Here, we show that when an insulator is subjected to a fast high-voltage pulse, the magnetic field due to disp… more
Date: July 17, 2007
Creator: Harris, J. R.; Caporaso, G. J.; Blackfield, D. & Chen, Y. J.
Partner: UNT Libraries Government Documents Department
open access

Detailed chemical kinetic oxidation mechanism for a biodiesel surrogate

Description: A detailed chemical kinetic mechanism has been developed and used to study the oxidation of methyl decanoate, a surrogate for biodiesel fuels. This model has been built by following the rules established by Curran et al. for the oxidation of n-heptane and it includes all the reactions known to be pertinent to both low and high temperatures. Computed results have been compared with methyl decanoate experiments in an engine and oxidation of rapeseed oil methyl esters in a jet stirred reactor. An … more
Date: September 17, 2007
Creator: Herbinet, O; Pitz, W J & Westbrook, C K
Partner: UNT Libraries Government Documents Department
open access

Parameterized Beyond-Einstein Growth

Description: A single parameter, the gravitational growth index gamma, succeeds in characterizing the growth of density perturbations in the linear regime separately from the effects of the cosmic expansion. The parameter is restricted to a very narrow range for models of dark energy obeying the laws of general relativity but can take on distinctly different values in models of beyond-Einstein gravity. Motivated by the parameterized post-Newtonian (PPN) formalism for testing gravity, we analytically derive … more
Date: September 17, 2007
Creator: Linder, Eric; Linder, Eric V. & Cahn, Robert N.
Partner: UNT Libraries Government Documents Department
open access

Optical Beam Timing Monitor Experiments at the Advanced LightSource

Description: We present the initial results of an experimental study of abeam timing monitor based on an optoelectronic technique. This techniqueuses the electrical signal from a beam position monitor to modulate theamplitude of a train of laser pulses, converting timing jitter into anamplitude jitter. This modulation is then measured with a photodetectorand sampled by a fast ADC. This approach has already demonstrated sub-100fs resolution and promises even better results. Additionally, we areplanning to us… more
Date: June 17, 2007
Creator: Byrd, John; De Santis, Stefano; Wilcox, Rusell & Yan, Yin
Partner: UNT Libraries Government Documents Department
open access

The Kinematics of Molecular Cloud Cores in the Presence of Driven and Decaying Turbulence: Comparisons with Observations

Description: In this study we investigate the formation and properties of prestellar and protostellar cores using hydrodynamic, self-gravitating Adaptive Mesh Refinement simulations, comparing the cases where turbulence is continually driven and where it is allowed to decay. We model observations of these cores in the C{sup 18}O(2 {yields} 1), NH{sub 3}(1, 1), and N{sub 2}H{sup +}(1 {yields} 0) lines, and from the simulated observations we measure the linewidths of individual cores, the linewidths of the su… more
Date: December 17, 2007
Creator: Offner, S R; Krumholz, M R; Klein, R I & McKee, C F
Partner: UNT Libraries Government Documents Department
open access

Engineered and Administrative Safety Systems for the Control of Prompt Radiation Hazards at Accelerator Facilities

Description: The ANSI N43.1 Standard, currently in revision (ANSI 2007), sets forth the requirements for accelerator facilities to provide adequate protection for the workers, the public and the environment from the hazards of ionizing radiation produced during and from accelerator operations. The Standard also recommends good practices that, when followed, provide a level of radiation protection consistent with those established for the accelerator communities. The N43.1 Standard is suitable for all accele… more
Date: December 17, 2007
Creator: Liu, James C.; Vylet, Vashek & Walker, Lawrence S.
Partner: UNT Libraries Government Documents Department
open access

SUSY Unparticle and Conformal Sequestering

Description: We investigate unparticle physics with supersymmetry (SUSY). The SUSY breaking effects due to the gravity mediation induce soft masses for the SUSY unparticles and hence break the conformal invariance. The unparticle physics observable in near future experiments is only consistent if the SUSY breakingeffects from the hidden sector to the standard model sector are dominated by the gauge mediation, or if the SUSY breaking effects to the unparticle sector are sufficiently sequestered. We argue tha… more
Date: July 17, 2007
Creator: Nakayama, Yu & Nakayama, Yu
Partner: UNT Libraries Government Documents Department
open access

Dihadron Tomography of High-Energy Nuclear Collisions inNext-to-Leading Order Perturbative QCD

Description: Back-to-back dihadron spectra in high-energy heavy-ioncollisions are studied within the next-to-leading order (NLO)perturbative QCD parton model with jet quenching incorporated viamodified jet fragmentation functions due to radiative parton energy lossin dense medium. The experimentally observed appearance of back-to-backdihadron sat high p_T is found to originate mainly from jet pairsproduced close and tangential to the surface of the dense matter.However, a substantial fraction of observed hi… more
Date: January 17, 2007
Creator: Zhang, Hanzhong; Owens, Joseph F.; Wang, Enke & Wang, Xin-Nian
Partner: UNT Libraries Government Documents Department
open access

Two-stage sintering inhibits abnormal grain growth during beta to alpha transformation in SiC

Description: Free sintering of SiC with Al, B, and C additions in two successive stages, first under nitrogen and then under argon, produced a near full-density ceramic with equiaxed grain structure. The beta to alpha transformation proceeded to completion; however, the grain shape remained equiaxed due to the action of nitrogen present during the first stage of sintering. It is found that the beta to alpha transformation is necessary but not sufficient for producing the microstructure of interlocking plate… more
Date: September 17, 2007
Creator: Kueck, Aaron M. & De Jonghe, Lutgard C.
Partner: UNT Libraries Government Documents Department
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