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Status of the SPARC Project (open access)

Status of the SPARC Project

The SPARC project has entered its installation phase at the Frascati National Laboratories of INFN: its main goal, the promotion of an R&D activity oriented to the development of a high brightness photoinjector to drive SASE-FEL experiments, is being vigorously pursued by a collaboration among ENEA-INFN-CNR-Universita di Roma Tor Vergata-INFM-ST. In this paper we will report on the installation and test of some major components, like Ti:Sa laser system, RF gun and RF power system. Advancements in the control and beam diagnostics systems will also be reported, in particular on the emittance-meter device for beam emittance measurements in the drift space downstream the RF gun. Recent results on laser pulse shaping show the feasibility of producing 10 ps flat-top laser pulses in the UV with rise time below 1 ps. First FEL experiments have been proposed, using SASE, seeding and non-linear resonant harmonics.
Date: January 25, 2006
Creator: Alesini, D.; Bertolucci, S.; Bellaveglia, M.; Biagini, M.E.; Boni, R.; Boscolo, M. et al.
System: The UNT Digital Library
Evaluating Fenestration Products for Zero-Energy Buildings: Issuesfor Discussion (open access)

Evaluating Fenestration Products for Zero-Energy Buildings: Issuesfor Discussion

Computer modeling to determine fenestration product energy properties (U-factor, SHGC, VT) has emerged as the most cost-effective and accurate means to quantify them. Fenestration product simulation tools have been effective in increasing the use of low-e coatings and gas fills in insulating glass and in the widespread use of insulating frame designs and materials. However, for more efficient fenestration products (low heat loss products, dynamic products, products with non-specular optical characteristics, light re-directing products) to achieve widespread use, fenestration modeling software needs to be improved. This paper addresses the following questions: (1) Are the current properties (U, SHGC, VT) calculated sufficient to compare and distinguish between windows suitable for Zero Energy Buildings and conventional window products? If not, what data on the thermal and optical performance, on comfort, and on peak demand of windows is needed. (2) Are the algorithms in the tools sufficient to model the thermal and optical processes? Are specific heat transfer and optical effects not accounted for? Is the existing level of accuracy enough to distinguish between products designed for Zero Energy Buildings? Is the current input data adequate?
Date: July 25, 2006
Creator: Arasteh, Dariush; Curcija, Charlie; Huang, Joe; Huizenga,Charlie & Kohler, Christian
System: The UNT Digital Library
Measurement of the Mass and Width and Study of the Spin of the Xi(1690)0 Resonance from Lambdac+ --> Lambda anti-K0 K+ Decay at BaBar (open access)

Measurement of the Mass and Width and Study of the Spin of the Xi(1690)0 Resonance from Lambdac+ --> Lambda anti-K0 K+ Decay at BaBar

The {Xi}(1690){sup 0} resonance is observed in the {Lambda}{bar K}{sup 0} channel in the decay {Lambda}{sub c}{sup +} {yields} {Lambda}{bar K}{sup 0}K{sup +}, from a data sample corresponding to a total integrated luminosity of {approx} 200 fb{sup -1} recorded by the BABAR detector at the PEP-II asymmetric-energy e+e- collider operating at {approx} 10.58 GeV and {approx} 10.54 GeV center-of-mass energies. A fit to the Dalitz plot intensity distribution corresponding to the coherent superposition of amplitudes describing {Lambda}a{sub 0}(980){sup +} and {Xi}(1690){sup 0} K{sup +} production yields mass and width values of 1684.7 {+-} 1.3(stat.){sub -1.6}{sup +2.2}(syst.) MeV/c{sup 2}, and 8.1{sub -3.5}{sup +3.9}(stat.){sub -0.9}{sup +1.0}(syst.) MeV, respectively, for the {Xi}(1690){sup 0}, while the spin is found to be consistent with value of 1/2 on the basis of studies of the ({Lambda}K{sub S}) angular distribution.
Date: September 25, 2006
Creator: Aubert, B.
System: The UNT Digital Library
Best Angle to Orient Two Intersecting Lines (open access)

Best Angle to Orient Two Intersecting Lines

Fiducials in the form of intersecting straight lines are used to align the target in the final target chamber of the National Ignition Facility of Lawrence Livermore National Laboratory. One of the techniques used to locate these lines is the Hough transform. When two lines intersect at a 90 degree angle, it is tempting to orient the lines to horizontal and vertical directions. There are other possible angles at which the lines may be oriented. One question that arises while designing the fiducials is whether there is a preferred angle or range of angles that leads to higher accuracy. This work attempts to answer this question through detailed computer simulation.
Date: July 25, 2006
Creator: Awwal, A. S.; Ferguson, S. W. & Shull, P. B.
System: The UNT Digital Library
Killing Two Birds with One Stone: Can Real-Time Pricing SupportRetail Competition and Demand Response? (open access)

Killing Two Birds with One Stone: Can Real-Time Pricing SupportRetail Competition and Demand Response?

As retail choice states reach the end of their transitional, rate-cap periods, state regulators must decide what type of default supply service to provide to customers that have not switched to a competitive retail supplier. In a growing number of states, regulators have adopted real-time pricing (RTP) as the default service for large commercial and industrial (C&I) customers. Although this trend is driven chiefly by policy objectives related to retail competition, default service RTP may have the added benefit of stimulating demand response. To evaluate the potential role of RTP as a means to both ends--retail market development and demand response--we conducted a comprehensive review of experience with default RTP in the U.S. and examined the emergence of RTP as a product offering by competitive retail suppliers. Across the ten utilities with default RTP in place in 2005, between 5% and 35% of the applicable load remained on the rate. Based on interviews with competitive retailers, we find evidence to suggest that a comparable amount of load in these states has switched to hourly pricing arrangements with competitive retailers. Many customers on default or competitive hourly pricing are paying prices indexed to the real-time spot market, and thus have no …
Date: April 25, 2006
Creator: Barbose, Galen; Bharvirkar, Ranjit; Goldman, Charles; Hopper,Nicole & Neenan, Bernie
System: The UNT Digital Library
Simulation of lean premixed turbulent combustion (open access)

Simulation of lean premixed turbulent combustion

There is considerable technological interest in developingnew fuel-flexible combustion systems that can burn fuels such ashydrogenor syngas. Lean premixed systems have the potential to burn thesetypes of fuels with high efficiency and low NOx emissions due to reducedburnt gas temperatures. Although traditional scientific approaches basedon theory and laboratory experiment have played essential roles indeveloping our current understanding of premixed combustion, they areunable to meet the challenges of designing fuel-flexible lean premixedcombustion devices. Computation, with itsability to deal with complexityand its unlimited access to data, hasthe potential for addressing thesechallenges. Realizing this potential requires the ability to perform highfidelity simulations of turbulent lean premixed flames under realisticconditions. In this paper, we examine the specialized mathematicalstructure of these combustion problems and discuss simulation approachesthat exploit this structure. Using these ideas we can dramatically reducecomputational cost, making it possible to perform high-fidelitysimulations of realistic flames. We illustrate this methodology byconsidering ultra-lean hydrogen flames and discuss how this type ofsimulation is changing the way researchers study combustion.
Date: June 25, 2006
Creator: Bell, John B.; Day, Marcus S.; Almgren, Ann S.; Lijewski, MichaelJ.; Rendleman, Charles A.; Cheng, Robert K. et al.
System: The UNT Digital Library
[Article: New York Photo Shoot for Brilliant Magazine] (open access)

[Article: New York Photo Shoot for Brilliant Magazine]

Article about a photo shoot held in the streets of New York for the December 2006 issue of Brilliant Magazine.
Date: October 25, 2006
Creator: Bellati, Nally
System: The UNT Digital Library
Large releases from CO2 storage reservoirs: Analogs, scenarios,and modeling needs (open access)

Large releases from CO2 storage reservoirs: Analogs, scenarios,and modeling needs

While the purpose of geologic storage in deep salineformations is to trap greenhouse gases underground, the potential existsfor CO2 to escape from the target reservoir, migrate upward alongpermeable pathways, and discharge at the land surface. In this paper, weevaluate the potential for such CO2 discharges based on the analysis ofnatural analogs, where large releases of gas have been observed. We areparticularly interested in circumstances that could generate sudden,possibly self enhancing release events. The probability for such eventsmay be low, but the circumstances under which they occur and thepotential consequences need to be evaluated in order to designappropriate site-selection and risk-managementstrategies. Numericalmodeling of hypothetical test cases is suggested to determine criticalconditions for large CO2 releases, to evaluate whether such conditionsmay be possible at designated storage sites, and, if applicable, toevaluate the potential impacts of such events as well as designappropriate mitigation strategies.
Date: March 25, 2006
Creator: Birkholzer, Jens; Pruess, Karsten; Lewicki, Jennifer; Rutqvist,Jonny; Tsang, Chin-Fu & Karimjee, Anhar
System: The UNT Digital Library
Online Aerosol Mass Spectrometry of Single Micrometer-Sized Particles Containing Poly(ethylene glycol) (open access)

Online Aerosol Mass Spectrometry of Single Micrometer-Sized Particles Containing Poly(ethylene glycol)

Analysis of poly(ethylene glycol)(PEG)-containing particles by online single particle aerosol mass spectrometers equipped with laser desorption ionization (LDI) is reported. We demonstrate that PEG-containing particles are useful in the development of aerosol mass spectrometers because of their ease of preparation, low cost, and inherently recognizable mass spectra. Solutions containing millimolar quantities of PEGs were nebulized and, after drying, the resultant micrometer-sized PEG containing particles were sampled. LDI (266 nm) of particles containing NaCl and PEG molecules of average molecular weight <500 generated mass spectra reminiscent of mass spectra of PEG collected by other MS schemes including the characteristic distribution of positive ions (Na{sup +} adducts) separated by the 44 Da of the ethylene oxide units separating each degree of polymerization. PEGs of average molecular weight >500 were detected from particles that also contained t the tripeptide tyrosine-tyrosine-tyrosine or 2,5-dihydroxybenzoic acid, which were added to nebulized solutions to act as matrices to assist LDI using pulsed 266 nm and 355 nm lasers, respectively. Experiments were performed on two aerosol mass spectrometers, one reflectron and one linear, that each utilize two time-of-flight mass analyzers to detect positive and negative ions created from a single particle. PEG-containing particles are currently being employed in …
Date: October 25, 2006
Creator: Bogan, M J; Patton, E; Srivastava, A; Martin, S; Fergenson, D; Steele, P et al.
System: The UNT Digital Library
Semileptonic B Decays at the B Factories (open access)

Semileptonic B Decays at the B Factories

Recent results on inclusive and exclusive semileptonic B decays from B Factories are presented. The status and perspectives of the determination of the CKM matrix elements V{sub ub} and V{sub cb} with semileptonic B decays is discussed.
Date: September 25, 2006
Creator: Bozzi, Concezio & /INFN, Ferrara
System: The UNT Digital Library
Extending the applicability of multigrid methods (open access)

Extending the applicability of multigrid methods

Multigrid methods are ideal for solving the increasingly large-scale problems that arise in numerical simulations of physical phenomena because of their potential for computational costs and memory requirements that scale linearly with the degrees of freedom. Unfortunately, they have been historically limited by their applicability to elliptic-type problems and the need for special handling in their implementation. In this paper, we present an overview of several recent theoretical and algorithmic advances made by the TOPS multigrid partners and their collaborators in extending applicability of multigrid methods. Specific examples that are presented include quantum chromodynamics, radiation transport, and electromagnetics.
Date: September 25, 2006
Creator: Brannick, J.; Brezina, M.; Falgout, R.; Manteuffel, T.; McCormick, S.; Ruge, J. et al.
System: The UNT Digital Library
Time-Space Position of Warm Dense Matter in Laser Plasma Interaction Process (open access)

Time-Space Position of Warm Dense Matter in Laser Plasma Interaction Process

Laser plasma interaction experiments have been perform performed using an fs Titanium Sapphire laser. Plasmas have been generated from planar PMMA targets using single laser pulses with 3.3 mJ pulse energy, 50 fs pulse duration at 800 nm wavelength. Electron density distributions of the plasmas in different delay times have been characterized by means of Nomarski Interferometry. Experimental data were cautiously compared with relevant 1D numerical simulation. Finally these results provide a first experience of searching for the time-space position of the so-called warm dense plasma in an ultra fast laser target interaction process. These experiments aim to prepare near solid-density plasmas for Thomson scattering experiments using the short wavelength free-electron laser FLASH, DESY Hamburg.
Date: September 25, 2006
Creator: Cao, L F; Uschmann, I; Forster, E; Zamponi, F; Kampfer, T; Fuhrmann, A et al.
System: The UNT Digital Library
Astrophysical Radiation Hydrodynamics: The Prospects for Scaling (open access)

Astrophysical Radiation Hydrodynamics: The Prospects for Scaling

The general principles of scaling are discussed, followed by a survey of the important dimensionless parameters of fluid dynamics including radiation and magnetic fields, and of non-LTE spectroscopy. The values of the parameters are reviewed for a variety of astronomical and laboratory environments. It is found that parameters involving transport coefficients--the fluid and magnetic Reynolds numbers--have enormous values for the astronomical problems that are not reached in the lab. The parameters that measure the importance of radiation are also scarcely reached in the lab. This also means that the lab environments are much closer to LTE than the majority of astronomical examples. Some of the astronomical environments are more magnetically dominated than anything in the lab. The conclusion is that a good astronomical environment for simulation in a given lab experiment can be found, but that the reverse is much more difficult.
Date: May 25, 2006
Creator: Castor, J I
System: The UNT Digital Library
Verification (mostly) for High Energy Density Radiation Transport: 5 Case Studies (open access)

Verification (mostly) for High Energy Density Radiation Transport: 5 Case Studies

None
Date: August 25, 2006
Creator: Castor, J I
System: The UNT Digital Library
ILC @ SLAC R&D Program for a Polarized RF Gun (open access)

ILC @ SLAC R&D Program for a Polarized RF Gun

Photocathode rf guns produce high-energy low-emittance electron beams. DC guns utilizing GaAs photocathodes have proven successful for generating polarized electron beams for accelerators, but they require rf bunching systems that significantly increase the transverse emittance of the beam. With higher extraction field and beam energy, rf guns can support higher current densities at the cathode. The source laser system can then be used to generate the high peak current, relatively low duty-factor micropulses required by the ILC without the need for post-extraction rf bunching. The net result is that the injection system for a polarized rf gun can be identical to that for an unpolarized rf gun. However, there is some uncertainty as to the survivability of an activated GaAs cathode in the environment of an operating rf gun. Consequently, before attempting to design a polarized rf gun for the ILC, SLAC plans to develop an rf test gun to demonstrate the rf operating conditions suitable for an activated GaAs cathode.
Date: January 25, 2006
Creator: Clendenin, J. E.; Brachman, A.; Dowell, D. H.; Garwin, E. L.; Ioakemidi, K.; Kirby, R. E. et al.
System: The UNT Digital Library
Evaluation of Techniques to Detect Significant Network Performance Problems using End-to-End Active Network Measurements (open access)

Evaluation of Techniques to Detect Significant Network Performance Problems using End-to-End Active Network Measurements

End-to-End fault and performance problems detection in wide area production networks is becoming increasingly hard as the complexity of the paths, the diversity of the performance, and dependency on the network increase. Several monitoring infrastructures are built to monitor different network metrics and collect monitoring information from thousands of hosts around the globe. Typically there are hundreds to thousands of time-series plots of network metrics which need to be looked at to identify network performance problems or anomalous variations in the traffic. Furthermore, most commercial products rely on a comparison with user configured static thresholds and often require access to SNMP-MIB information, to which a typical end-user does not usually have access. In our paper we propose new techniques to detect network performance problems proactively in close to realtime and we do not rely on static thresholds and SNMP-MIB information. We describe and compare the use of several different algorithms that we have implemented to detect persistent network problems using anomalous variations analysis in real end-to-end Internet performance measurements. We also provide methods and/or guidance for how to set the user settable parameters. The measurements are based on active probes running on 40 production network paths with bottlenecks varying from …
Date: January 25, 2006
Creator: Cottrell, R.Les; Logg, Connie; Chhaparia, Mahesh; Grigoriev, Maxim; Haro, Felipe; Nazir, Fawad et al.
System: The UNT Digital Library
Recovery of a CVD diamond detection system from strong pulses of laser produced x-rays (open access)

Recovery of a CVD diamond detection system from strong pulses of laser produced x-rays

We are studying the response of a CVD diamond detector to a strong x-ray pulse followed by a second weaker pulse arriving 50 to 300 ns later, with a contrast in amplitude of about 1000. These tests, performed at the LLNL Jupiter laser facility, are intended to produce charge carrier densities similar to those expected during a DT implosion at NIF, where a large 14.1 MeV neutron pulse is followed by a weak downscattered neutron signal produced by slower 6-10 MeV neutrons. The number of downscattered neutrons must be carefully measured in order to obtain an accurate value for the areal density, which is proportional to the ratio of downscattered to primary neutrons. The effects of the first strong pulse may include saturation of the diamond wafer, saturation of the oscilloscope, or saturation of the associated power and data acquisition electronics. We are presenting a double pulse experiment that will use a system of several polycrystalline CVD diamond detectors irradiated by 8.6 keV x-rays emitted from a zinc target. We will discuss implication for a NIF areal density measurement.
Date: April 25, 2006
Creator: Dauffy, L S; Koch, J A; Izumi, N; Tommasini, R & Lerche, R A
System: The UNT Digital Library
30th Actinide Separations Conference, PNNL-SA-50126 (open access)

30th Actinide Separations Conference, PNNL-SA-50126

Program booklet for the 30th Actinide Separations Conference. Contains agenda and abstracts for 27 poster and 38 oral presentations to be made during the 3-day meeting, May 23-25, 2006.
Date: May 25, 2006
Creator: Delegard, Calvin H.
System: The UNT Digital Library
Hard X-ray Imaging for Measuring Laser Absorption Spatial Profiles on the National Ignition Facility (open access)

Hard X-ray Imaging for Measuring Laser Absorption Spatial Profiles on the National Ignition Facility

Hard x-ray (''Thin wall'') imaging will be employed on the National Ignition Facility (NIF) to spatially locate laser beam energy deposition regions on the hohlraum walls in indirect drive Inertial Confinement Fusion (ICF) experiments, relevant for ICF symmetry tuning. Based on time resolved imaging of the hard x-ray emission of the laser spots, this method will be used to infer hohlraum wall motion due to x-ray and laser ablation and any beam refraction caused by plasma density gradients. In optimizing this measurement, issues that have to be addressed are hard x-ray visibility during the entire ignition laser pulse with intensities ranging from 10{sup 13} to 10{sup 15} W/cm{sup 2}, as well as simultaneous visibility of the inner and the outer laser drive cones. In this work we will compare the hard x-ray emission calculated by LASNEX and analytical modeling with thin wall imaging data recorded previously on Omega and during the first hohlraum experiments on NIF. Based on these calculations and comparisons the thin wall imaging will be optimized for ICF/NIF experiments.
Date: April 25, 2006
Creator: Dewald, E L; Jones, O S; Landen, O L; Suter, L; Amendt, P; Turner, R E et al.
System: The UNT Digital Library
Performance evaluation of eigensolvers in nanostructurecomputations (open access)

Performance evaluation of eigensolvers in nanostructurecomputations

None
Date: May 25, 2006
Creator: Dongarra, Jack; Langou, Julien; Tomov, Stanimire; Canning, Andrew; Marques, Osni & Wang, Lin-Wang
System: The UNT Digital Library
Towards bulk based preconditioning for quantum dotcomputations (open access)

Towards bulk based preconditioning for quantum dotcomputations

This article describes how to accelerate the convergence of Preconditioned Conjugate Gradient (PCG) type eigensolvers for the computation of several states around the band gap of colloidal quantum dots. Our new approach uses the Hamiltonian from the bulk materials constituent for the quantum dot to design an efficient preconditioner for the folded spectrum PCG method. The technique described shows promising results when applied to CdSe quantum dot model problems. We show a decrease in the number of iteration steps by at least a factor of 4 compared to the previously used diagonal preconditioner.
Date: May 25, 2006
Creator: Dongarra, Jack; Langou, Julien; Tomov, Stanimire; Channing,Andrew; Marques, Osni; Vomel, Christof et al.
System: The UNT Digital Library
A Variation of the F-Test for Determining Statistical Relevance ofParticular Parameters in EXAFS Fits (open access)

A Variation of the F-Test for Determining Statistical Relevance ofParticular Parameters in EXAFS Fits

A general problem when fitting EXAFS data is determining whether particular parameters are statistically significant. The F-test is an excellent way of determining relevancy in EXAFS because it only relies on the ratio of the fit residual of two possible models, and therefore the data errors approximately cancel. Although this test is widely used in crystallography (there, it is often called a 'Hamilton test') and has been properly applied to EXAFS data in the past, it is very rarely applied in EXAFS analysis. We have implemented a variation of the F-test adapted for EXAFS data analysis in the RSXAP analysis package, and demonstrate its applicability with a few examples, including determining whether a particular scattering shell is warranted, and differentiating between two possible species or two possible structures in a given shell.
Date: July 25, 2006
Creator: Downward, L.; Booth, C.H.; Lukens, W.W. & Bridges, F.
System: The UNT Digital Library
An Introduction to Algebraic Multigrid (open access)

An Introduction to Algebraic Multigrid

Algebraic multigrid (AMG) solves linear systems based on multigrid principles, but in a way that only depends on the coefficients in the underlying matrix. The author begins with a basic introduction to AMG methods, and then describes some more recent advances and theoretical developments
Date: April 25, 2006
Creator: Falgout, R D
System: The UNT Digital Library
Solid State Replacement of Rotating Mirror Cameras (open access)

Solid State Replacement of Rotating Mirror Cameras

Rotating mirror cameras have been the mainstay of mega-frame per second imaging for decades. There is still no electronic camera that can match a film based rotary mirror camera for the combination of frame count, speed, resolution and dynamic range. The rotary mirror cameras are predominantly used in the range of 0.1 to 100 micro-seconds per frame, for 25 to more than a hundred frames. Electron tube gated cameras dominate the sub microsecond regime but are frame count limited. Video cameras are pushing into the microsecond regime but are resolution limited by the high data rates. An all solid state architecture, dubbed ''In-situ Storage Image Sensor'' or ''ISIS'', by Prof. Goji Etoh, has made its first appearance into the market and its evaluation is discussed. Recent work at Lawrence Livermore National Laboratory has concentrated both on evaluation of the presently available technologies and exploring the capabilities of the ISIS architecture. It is clear though there is presently no single chip camera that can simultaneously match the rotary mirror cameras, the ISIS architecture has the potential to approach their performance.
Date: August 25, 2006
Creator: Frank, A M & Bartolick, J M
System: The UNT Digital Library