110 Matching Results

Search Results

Results: 1 - 24 next
open access

An Update on the Status of the NIF Power Conditioning System

Description: The National Ignition Facility (NIF) Power Conditioning System provides the pulsed excitation required to drive flashlamps in the laser's optical amplifiers. Modular in design, each of the 192 Main Energy Storage Modules (MESMs) stores up to 2.2 MJ of electrical energy in its capacitor bank before delivering the energy to 20 pairs of flashlamps in a 400 {micro}s pulse (10% power points). The peak current of each MESM discharge is 0.5 MA. Production, installation, commissioning and operation of … more
Date: September 6, 2007
Creator: Arnold, P. A.; Hulsey, S.; Ullery, G. T.; Petersen, D. E.; Pendleton, D. L.; Ollis, C. W. et al.
Partner: UNT Libraries Government Documents Department
open access

Open Cavity Solutions to the Rf in Magnetic Field Problem.

Description: It has been observed [1] that breakdown in an 805 MHz pill-box cavity occurs at much lower gradients as an external axial magnetic field is increased. This effect was not observed with on open iris cavity. It is proposed that this effect depends on the relative angles of the magnetic and maximum electric fields: parallel in the pill-box case; at an angle in the open iris case. If so, using an open iris structure with solenoid coils in the irises should perform even better. A lattice, using this… more
Date: August 6, 2007
Creator: Palmer, R. B.; Berg, J. S.; Fernow, R. C.; Gallardo, J. C. & Kirk, H. G.
Partner: UNT Libraries Government Documents Department
open access

Using Ffags in the Creation of Neutrino Beams.

Description: A number of accelerator-based facilities have been proposed for the creation of neutrino beams: superbeams, neutrino factories, and beta beams. Fixed field alternating gradient accelerators (FFAGs) have potential uses in all of these facilities. Superbeams and neutrino factories require high power proton drivers for the production of pions; FFAGs can beneficial for accelerating protons for those machines. FFAGs can reduce the cost of accelerating muons in a neutrino factory because they enable … more
Date: August 6, 2007
Creator: Berg, J. S.
Partner: UNT Libraries Government Documents Department
open access

Monte Carlo Methods in the Physical Sciences

Description: I will review the role that Monte Carlo methods play in the physical sciences. They are very widely used for a number of reasons: they permit the rapid and faithful transformation of a natural or model stochastic process into a computer code. They are powerful numerical methods for treating the many-dimensional problems that derive from important physical systems. Finally, many of the methods naturally permit the use of modern parallel computers in efficient ways. In the presentation, I will em… more
Date: June 6, 2007
Creator: Kalos, M. H.
Partner: UNT Libraries Government Documents Department
open access

D-dualized D-brane

Description: We further investigate the dimensional duality (D-duality) proposed in arXiv: 0705.0550 by mainly focusing on the properties of D-branes in this background. We derive the world-sheet correspondence of static D-branes, and discuss the fate of non-static D-branes from the world-sheet viewpoint. The quantum string production with or without D-branes is also studied fromthe time-like Liouville theory. We find that the closed string production from the background is much larger than that from D-bran… more
Date: June 6, 2007
Creator: Nakayama, Yu & Nakayama, Yu
Partner: UNT Libraries Government Documents Department
open access

The US Long Baseline Neutrino Experiment Study

Description: The US Long Baseline Neutrino Experiment Study was commissioned jointly by Brookhaven National Laboratory (BNL)and Fermi National Accelerator Laboratory (FNAL) to investigate the potential for future U.S. based long baseline neutrino oscillation experiments using MW class conventional neutrino beams that can be produced at FNAL. The experimental baselines are based on two possible detector locations: (1) off-axis to the existing FNAL NuMI beamline at baselines of 700 to 810 km and (2) NSF's pro… more
Date: August 6, 2007
Creator: Bishai, M.
Partner: UNT Libraries Government Documents Department
open access

Discovery of Non-random Spatial Distribution of Impacts in the Stardust Cometary Collector

Description: We report the discovery that impacts in the Stardust cometary collector are not distributed randomly in the collecting media, but appear to be clustered on scales smaller than {approx} 10 cm. We also report the discovery of at least two populations of oblique tracks. We evaluated several hypotheses that could explain the observations. No hypothesis was consistent with all the observations, but the preponderance of evidence points toward at least one impact on the central Whipple shield of the s… more
Date: April 6, 2007
Creator: Westphal, A. J.; Bastien, R. K.; Borg, J.; Bridges, J.; Brownlee, D. E.; Burchell, M. J. et al.
Partner: UNT Libraries Government Documents Department
open access

Isopiestic Investigation of the Osmotic and Activity Coefficients of {yMgCl2 + (1 - y)MgSO4}(aq) and the Osmotic Coefficients of Na2SO4.MgSO4(aq) at 298.15 K

Description: Isopiestic vapor pressure measurements were made for {l_brace}yMgCl{sub 2} + (1-y)MgSO{sub 4}{r_brace}(aq) solutions with MgCl{sub 2} ionic strength fractions of y = 0, 0.1997, 0.3989, 0.5992, 0.8008, and (1) at the temperature 298.15 K, using KCl(aq) as the reference standard. These measurements for the mixtures cover the ionic strength range I = 0.9794 to 9.4318 mol {center_dot} kg{sup -1}. In addition, isopiestic measurements were made with NaCl(aq) as reference standard for mixtures of {l_b… more
Date: June 6, 2007
Creator: Miladinovic, J; Ninkovic, R; Todorovic, M & Rard, J A
Partner: UNT Libraries Government Documents Department
open access

Visualization of Scalar Adaptive Mesh Refinement Data

Description: Adaptive Mesh Refinement (AMR) is a highly effective computation method for simulations that span a large range of spatiotemporal scales, such as astrophysical simulations, which must accommodate ranges from interstellar to sub-planetary. Most mainstream visualization tools still lack support for AMR grids as a first class data type and AMR code teams use custom built applications for AMR visualization. The Department of Energy's (DOE's) Science Discovery through Advanced Computing (SciDAC) Vis… more
Date: December 6, 2007
Creator: VACET; Weber, Gunther; Weber, Gunther H.; Beckner, Vince E.; Childs, Hank; Ligocki, Terry J. et al.
Partner: UNT Libraries Government Documents Department
open access

Regional Analysis of Lg Attenuation: Comparison of 1D Methods in Northern California and Application to the Yellow Sea / Korean Peninsula

Description: The measurement of regional attenuation Q{sup -1} can produce method dependent results. The discrepancies among methods are due to differing parameterizations (e.g., geometrical spreading rates), employed datasets (e.g., choice of path lengths and sources), and methodologies themselves (e.g., measurement in the frequency or time domain). We apply the coda normalization (CN), two-station (TS), reverse two-station (RTS), source-pair/receiver-pair (SPRP), and the new coda-source normalization (CS)… more
Date: July 6, 2007
Creator: Ford, S R; Dreger, D S; Mayeda, K M; Walter, W R; Malagnini, L & Phillips, W S
Partner: UNT Libraries Government Documents Department
open access

More visible effects of the hidden sector

Description: There is a growing appreciation that hidden sector dynamics may affect the supersymmetry breaking parameters in the visible sector (supersymmetric standard model), especially when the dynamics is strong and superconformal. We point out that there are effects that have not been previously discussed in the literature. For example, the gaugino masses are suppressed relative to the gravitino mass. We discuss their implications in the context of various mediation mechanisms. The issues discussed inc… more
Date: September 6, 2007
Creator: Murayama, Hitoshi; Murayama, Hitoshi; Nomura, Yasunori & Poland, David
Partner: UNT Libraries Government Documents Department
open access

R AND D TOPICS FOR NEUTRINO FACTORY ACCELERATION.

Description: The muons in a neutrino factory must be accelerated from the energy of the capture, phase rotation, and cooling systems (around 120 MeV kinetic energy) to the energy of the storage ring (around 25 GeV). This is done with a sequence of accelerators of different types: a linac, one or more recirculating linear accelerators, and finally one or more fixed field alternating gradient accelerators (FFAGs). I discuss the R&D that is needed to arrive at a complete system which we can have confidence… more
Date: August 6, 2007
Creator: SCOTT,J.S.
Partner: UNT Libraries Government Documents Department
open access

Image Ellipticity from Atmospheric Aberrations

Description: We investigate the ellipticity of the point-spread function (PSF) produced by imaging an unresolved source with a telescope, subject to the effects of atmospheric turbulence. It is important to quantify these effects in order to understand the errors in shape measurements of astronomical objects, such as those used to study weak gravitational lensing of field galaxies. The PSF modeling involves either a Fourier transform of the phase information in the pupil plane or a ray-tracing approach, whi… more
Date: March 6, 2007
Creator: de Vries, W. H.; Olivier, S. S.; Asztalos, S. J.; Rosenberg, L. J. & Baker, K. L.
Partner: UNT Libraries Government Documents Department
open access

Identifying Isotropic Events Using an Improved Regional Moment Tensor Inversion Technique

Description: Using a regional time-domain waveform inversion for the complete moment tensor we calculate the deviatoric and isotropic source components for several explosions at the Nevada Test Site as well as earthquakes, and collapses in the surrounding region of the western US. The events separate into specific populations according to their deviation from a pure double-couple and ratio of isotropic to deviatoric energy. The separation allows for anomalous event identification and discrimination between … more
Date: July 6, 2007
Creator: Ford, S R; Dreger, D S & Walter, W R
Partner: UNT Libraries Government Documents Department
open access

The Emma Lattice.

Description: EMMA is a 10 to 20MeV electron ring designed to test our understanding of beam dynamics in a relativistic linear non-scaling fixed field alternating gradient accelerator (FFAG). I will give a basic review of the EMMA lattice parameters. Then I will review the different lattice configurations that we would like to have for EMMA. Finally, I will briefly discuss the process of commissioning each lattice configuration.
Date: August 6, 2007
Creator: Berg, J. S.
Partner: UNT Libraries Government Documents Department
open access

Volume Independence in Large Nc QCD-like Gauge Theories

Description: Volume independence in large N{sub c} gauge theories may be viewed as a generalized orbifold equivalence. The reduction to zero volume (or Eguchi-Kawai reduction) is a special case of this equivalence. So is temperature independence in confining phases. A natural generalization concerns volume independence in ''theory space'' of quiver gauge theories. In pure Yang-Mills theory, the failure of volume independence for sufficiently small volumes (at weak coupling) due to spontaneous breaking of ce… more
Date: February 6, 2007
Creator: Kovtun, Pavel; Unsal, Mithat & Yaffe, Laurence G.
Partner: UNT Libraries Government Documents Department
open access

Ionization-Induced Electron Trapping in Ultrarelativistic Plasma Wakes

Description: The onset of trapping of electrons born inside a highly relativistic, 3D beam-driven plasma wake is investigated. Trapping occurs in the transition regions of a Li plasma confined by He gas. Li plasma electrons support the wake, and higher ionization potential He atoms are ionized as the beam is focused by Li ions and can be trapped. As the wake amplitude is increased, the onset of trapping is observed. Some electrons gain up to 7.6 GeV in a 30.5 cm plasma. The experimentally inferred trapping … more
Date: April 6, 2007
Creator: Oz, E.; Deng, S.; Katsouleas, T.; Muggli, P.; Barnes, C. D.; Blumenfeld, I. et al.
Partner: UNT Libraries Government Documents Department
open access

RADRELAY RADIOLOGICAL DATA LINK DEVICE

Description: The RadRelay effort developed small, field appropriate, portable prototype devices that allow radiological spectra to be downloaded from field radiological detectors, like the identiFINDER-U, and transmitted to land based experts. This communications capability was designed for the U. S. Coast Guard (USCG) but is also applicable to the Customs and Border Protection (CBP) personnel working in remote locations. USCG Level II personnel currently use the identiFINDER-U Hand-Held Radioisotope ID Dev… more
Date: November 6, 2007
Creator: Harpring, L & Frank Heckendorn, F
Partner: UNT Libraries Government Documents Department
open access

An atomic force microcopy study of the mechanical and electricalproperties of monolayer films of molecules with aromatic end groups

Description: The effect of intermolecular {pi}-{pi} stacking on the electrical and mechanical properties of monolayer films molecules containing aromatic groups was studied using atomic force microscopy. Two types of aromatic molecules, (4-mercaptophenyl) anthrylacetylene (MPAA) and (4-mercaptophenyl)-phenylacetylene (MPPA) were used as model systems with different {pi}-{pi} stacking strength. Monolayer films of these molecules on Au(111) surfaces exhibited conductivities differing by more than one order of… more
Date: September 6, 2007
Creator: Fang, Liang; Park, J.Y.; Ma, H.; Jen, A.K.-Y. & Salmeron, M.
Partner: UNT Libraries Government Documents Department
open access

Geometric metastability, quivers and holography

Description: We use large N duality to study brane/anti-brane configurations on a class of Calabi-Yau manifolds. With only branes present, the Calabi-Yau manifolds in question give rise to N=2 ADE quiver theories deformed by superpotential terms. We show that the large N duality conjecture of hep-th/0610249 reproduces correctly the known qualitative features of the brane/anti-brane physics. In the supersymmetric case, the gauge theories have Seiberg dualities which are represented as flops in the geometry. … more
Date: September 6, 2007
Creator: Aganagic, Mina; Aganagic, Mina; Beem, Christopher & Freivogel, Ben
Partner: UNT Libraries Government Documents Department
open access

Application of exterior complex scaling to positron-hydrogencollisions including rearrangement

Description: The first application of an exterior complex scaling method to an atomic scattering problem with distinct rearrangement channels is reported. Calculations are performed for positron-hydrogen collisions in an s-wave model employing an electron-positron potential of V{sub 12} = -(8+(r{sub 1}-r{sub 2}){sup 2}){sup 1/2}, using the time-independent propagating exterior complex scaling (PECS) method. This potential has the correct long-range Coulomb tail of the full problem and the results demonstrat… more
Date: December 6, 2007
Creator: Bartlett, Philip L.; Stelbovics, Andris T.; Rescigno, Thomas N. & McCurdy, C. William
Partner: UNT Libraries Government Documents Department
open access

A High Resolution Hydrometer Phase Classifier Based on Analysis of Cloud Radar Doppler Spectra.

Description: The lifecycle and radiative properties of clouds are highly sensitive to the phase of their hydrometeors (i.e., liquid or ice). Knowledge of cloud phase is essential for specifying the optical properties of clouds, or else, large errors can be introduced in the calculation of the cloud radiative fluxes. Current parameterizations of cloud water partition in liquid and ice based on temperature are characterized by large uncertainty (Curry et al., 1996; Hobbs and Rangno, 1998; Intriery et al., 200… more
Date: August 6, 2007
Creator: Luke,E. & Kollias, P.
Partner: UNT Libraries Government Documents Department
Back to Top of Screen