53 Matching Results

Search Results

Results: 1 - 24 next
open access

Sigma: Web Retrieval Interface for Nuclear Reaction Data

Description: The authors present Sigma, a Web-rich application which provides user-friendly access in processing and plotting of the evaluated and experimental nuclear reaction data stored in the ENDF-6 and EXFOR formats. The main interface includes browsing using a periodic table and a directory tree, basic and advanced search capabilities, interactive plots of cross sections, angular distributions and spectra, comparisons between evaluated and experimental data, computations between different cross sectio… more
Date: June 24, 2008
Creator: Pritychenko,B. & Sonzogni, A.A.
Partner: UNT Libraries Government Documents Department
open access

Long-range and head-on beam-beam compensation studies in RHIC with lessons for the LHC

Description: Long-range as well as head-on beam-beam effects are expected to limit the LHC performance with design parameters. They are also important consideration for the LHC upgrades. To mitigate long-range effects current carrying wires parallel to the beam were proposed. Two such wires are installed in RHIC where they allow studying the effect of strong long-range beam-beam effects, as well as the compensation of a single long-range interaction. The tests provide benchmark data for simulations and anal… more
Date: November 24, 2008
Creator: Fischer, W.; Luo, Y.; Abreu, N.; Calaga, R.; Montag, C.; Robert-Demolaize, G. et al.
Partner: UNT Libraries Government Documents Department
open access

Emittance and Current of Electrons Trapped in a Plasma Wakefield Accelerator

Description: In recent experiments plasma electrons became trapped in a plasma wakefield accelerator (PWFA). The transverse size of these trapped electrons on a downstream diagnostic yields an upper limit measurement of transverse normalized emittance divided by peak current, {var_epsilon}{sub N,x}/I. The lowest upper limit for {var_epsilon}{sub N,x}/I measured in the experiment is 1.3 {center_dot} 10{sup -10} m/A.
Date: September 24, 2008
Creator: Kirby, N.; Blumenfeld, I.; Clayton, C. E.; Decker, F. J.; Hogan, M. J.; Huang, C. et al.
Partner: UNT Libraries Government Documents Department
open access

Measurement of the tau- to eta pi-pi+pi-nu tau Branching Fraction and a Search for a Second-Class Current in the tau- to eta'(958)pi-nu tau Decay

Description: The {tau}{sup -} {yields} {eta}{pi}{sup -}{pi}{sup +}{pi}{sup -}{nu}{sub {tau}} decay with the {eta} {yields} {gamma}{gamma} mode is studied using 384 fb{sup -1} of data collected by the BABAR detector. The branching fraction is measured to be (1.60 {+-} 0.05 {+-} 0.11) x 10{sup -4}. It is found that {tau}{sup -} {yields} f{sub 1}(1285){pi}{sup -} {nu}{sub {tau}} {yields} {eta}{pi}{sup -}{pi}{sup +}{pi}{sup -}{nu}{sub {tau}} is the dominant decay mode with a branching fraction of (1.11 {+-} 0.0… more
Date: March 24, 2008
Creator: Aubert, B.; Bona, M.; Boutigny, D.; Karyotakis, Y.; Lees, J. P.; Poireau, V. et al.
Partner: UNT Libraries Government Documents Department
open access

The impact of retail rate structures on the economics of commercial photovoltaic systems in California

Description: This article examines the impact of retail electricity rate design on the economic value of grid-connected photovoltaic (PV) systems, focusing on commercial customers in California. Using 15-min interval building load and PV production data from a sample of 24 actual commercial PV installations, we compare the value of the bill savings across 20 commercial-customer retail electricity rates currently offered in the state. Across all combinations of customers and rates, we find that the annual bi… more
Date: June 24, 2008
Creator: Mills, Andrew D.; Wiser, Ryan; Barbose, Galen & Golove, William
Partner: UNT Libraries Government Documents Department
open access

Can cross sections be accurately known for priori?

Description: Distinct maxima and minima in the neutron total cross section uncertainties were observed in our large scale covariance calculations using a spherical optical potential. In this contribution we investigate the physical origin of this oscillating structure. Specifically, we analyze the case of neutron reactions on {sup 56}Fe, for which total cross section uncertainties are characterized by the presence of five distinct minima at 0.1, 1.1, 5, 25, and 70 MeV. To investigate their origin, we calcul… more
Date: June 24, 2008
Creator: Pigni, M. T.; Dietrich, F. S.; Herman, M. & Oblozinsky, P.
Partner: UNT Libraries Government Documents Department
open access

Depth-resolved soft x-ray photoelectron emission microscopy in nanostructures via standing-wave excited photoemission

Description: We present an extension of conventional laterally resolved soft x-ray photoelectron emission microscopy. A depth resolution along the surface normal down to a few {angstrom} can be achieved by setting up standing x-ray wave fields in a multilayer substrate. The sample is an Ag/Co/Au trilayer, whose first layer has a wedge profile, grown on a Si/MoSi2 multilayer mirror. Tuning the incident x-ray to the mirror Bragg angle we set up standing x-ray wave fields. We demonstrate the resulting depth re… more
Date: November 24, 2008
Creator: Kronast, F.; Ovsyannikov, R.; Kaiser, A.; Wiemann, C.; Yang, S. -H.; Locatelli, A. et al.
Partner: UNT Libraries Government Documents Department
open access

Measurement of electron clouds in large accelerators by microwave dispersion

Description: Clouds of low energy electrons in the vacuum beam pipes of accelerators of positively charged particle beams present a serious limitation for operation at high currents. Furthermore, it is difficult to probe their density over substantial lengths of the beam pipe. We have developed a novel technique to directly measure the electron cloud density via the phase shift induced in a TE wave transmitted over a section of the accelerator and used it to measure the average electron cloud density over a… more
Date: January 24, 2008
Creator: Desantis, Stefano; De Santis, Stefano; Byrd, John M.; Sonnad, Kiran G.; Pivi, Mauro T.F.; Krasnykh, Anatoly et al.
Partner: UNT Libraries Government Documents Department
open access

Analyses of Oxyanion Materials by Prompt Gamma Activation Analysis

Description: Prompt gamma activation analysis (PGAA) has been used to analyze metal ion oxyanion materials that have multiple applications, including medicine, materials, catalysts, and electronics. The significance for the need for accurate, highly sensitive analyses for the materials is discussed in the context of quality control of end products containing the parent element in each material. Applications of the analytical data for input to models and theoretical calculations related to the electronic and… more
Date: March 24, 2008
Creator: Firestone, Richard B.; Perry, D. L.; English, G. A.; Firestone, R. B.; Leung, K. N.; Garabedian, G. et al.
Partner: UNT Libraries Government Documents Department
open access

Experimental Tests of Cooling: Expectations and Additional Needs

Description: Cooling is a critical aspect for a high-performance Neutrino Factory or a MuonCollider. For this reason, considerable effort is being put toward theexperimental verification of this technique. The international Muon IonizationCooling Experiment, MICE, was approved to operate at Rutherford AppletonLaboratory (RAL) in the UK and beam line commissioning commenced in March, 2008. The MICE collaboration comprises about 130 scientists and engineers from Asia, Europe, and the U.S. In this paper we pre… more
Date: September 24, 2008
Creator: Zisman, Michael S
Partner: UNT Libraries Government Documents Department
open access

Development of a Multi Megawatt Circulator for X Band

Description: Research is in progress on a TeV-scale linear collider that will operate at 5-10 times the energy of present-generation accelerators. This will require development of high power RF sources generating of 50-100 MW per source. Transmission of power at this level requires overmoded waveguide to avoid breakdown. In particular, the TE{sub 01} circular waveguide mode is currently the mode of choice for waveguide transmission at Stanford Linear Accelerator Center (SLAC) in the Multimode Delay Line Dis… more
Date: March 24, 2008
Creator: Neilson, J.; Ives, L. & Tantawi, S. G.
Partner: UNT Libraries Government Documents Department
open access

Vacuum-Ultraviolet (VUV) Photoionization of Small Methanol and Methanol-Water Clusters

Description: In this work, we report on the vacuum-ultraviolet (VUV) photoionization of small methanol and methanol-water clusters. Clusters of methanol with water are generated via co-expansion of the gas phase constituents in a continuous supersonic jet expansion of methanol and water seeded in Ar. The resulting clusters are investigated by single photon ionization with tunable vacuum-ultraviolet synchrotron radiation and mass analyzed using reflectron mass spectrometry. Protonated methanol clusters of th… more
Date: April 24, 2008
Creator: Kostko, Oleg; Belau, Leonid; Wilson, Kevin R. & Ahmed, Musahid
Partner: UNT Libraries Government Documents Department
open access

Quantitative comparison between Type Ia supernova spectra at low and high redshifts: A case study

Description: We develop a method to measure the strength of the absorption features in type Ia supernova (SN Ia) spectra and use it to make a quantitative comparisons between the spectra of type Ia supernovae at low and high redshifts. In this case study, we apply the method to 12 high-redshift (0.212 = z = 0.912) SNe Ia observed by the Supernova Cosmology Project. Through measurements of the strengths of these features and of the blueshift of theabsorption minimum in Ca ii H&K, we show that the spectra… more
Date: March 24, 2008
Creator: Supernova Cosmology Project
Partner: UNT Libraries Government Documents Department
open access

Parametric Modeling of Transverse Phase Space of an RF Photoinjector

Description: High brightness electron beam sources such as rf photo-injectors as proposed for SASE FELs must consistently produce the desired beam quality. We report the results of a study in which a combined neural network (NN) and first-principles (FP) model is used to model the transverse phase space of the beam as a function of quadrupole strength, while beam charge, solenoid field, accelerator gradient, and linac voltage and phase are kept constant. The parametric transport matrix between the exit of t… more
Date: January 24, 2008
Creator: Hartman, E.; Sayyar-Rodsari, B.; Schweiger, C. A.; Lee, M. J.; Lui, P.; Paterson, Ewan et al.
Partner: UNT Libraries Government Documents Department
open access

PBXN-9 Ignition Kinetics and Deflagration Rates

Description: The ignition kinetics and deflagration rates of PBXN-9 were measured using specially designed instruments at LLNL and compared with previous work on similar HMX based materials. Ignition kinetics were measured based on the One Dimensional Time-to-Explosion combined with ALE3D modeling. Results of these experiments indicate that PBXN-9 behaves much like other HMX based materials (i.e. LX-04, LX-07, LX-10 and PBX-9501) and the dominant factor in these experiments is the type of explosive, not the… more
Date: April 24, 2008
Creator: Glascoe, E; Maienschein, J; Burnham, A; Koerner, J; Hsu, P & Wemhoff, A.
Partner: UNT Libraries Government Documents Department
open access

Absolute Bunch Length Measurements at the ALS by Incoherent Synchrotron Radiation Fluctuation Analysis

Description: By analyzing the pulse to pulse intensity fluctuations of the radiation emitted by a charge particle in the incoherent part of the spectrum, it is possible to extract information about the spatial distribution of the beam. At the Advanced Light Source (ALS) of the Lawrence Berkeley National Laboratory, we have developed and tested a simple scheme based on this principle that allows for the absolute measurement of the bunch length. A description of the method and the experimental results are pre… more
Date: January 24, 2008
Creator: Filippetto, D.; /Frascati; Sannibale, F.; Zolotorev, Max Samuil; /LBL, Berkeley; Stupakov, G.V. et al.
Partner: UNT Libraries Government Documents Department
open access

Deformed Matrix Models, Supersymmetric Lattice Twists and N=1/4 Supersymmetry

Description: A manifestly supersymmetric nonperturbative matrix regularization for a twisted version of N = (8, 8) theory on a curved background (a two-sphere) is constructed. Both continuum and the matrix regularization respect four exact scalar supersymmetries under a twisted version of the supersymmetry algebra. We then discuss a succinct Q = 1 deformed matrix model regularization of N = 4 SYM in d = 4, which is equivalent to a non-commutative A*{sub 4} orbifold lattice formulation. Motivated by recent p… more
Date: September 24, 2008
Creator: Unsal, Mithat
Partner: UNT Libraries Government Documents Department
open access

Actinic EUV mask inspection beyond 0.25 NA

Description: The SEMATECH Berkeley Actinic Inspection Tool (AIT) is an EUV-wavelength mask inspection microscope designed for direct aerial image measurements, and pre-commercial EUV mask research. Operating on a synchrotron bending magnet beamline, the AIT uses an off-axis Fresnel zoneplate lens to project a high-magnification EUV image directly onto a CCD camera. We present the results of recent system upgrades that have improved the imaging resolution, illumination uniformity, and partial coherence. Benc… more
Date: March 24, 2008
Creator: Goldberg, Kenneth A.; Mochi, Iacopo; Anderson, Erik H.; Rekawa, Seno. B.; Kemp, Charles D.; Huh, S. et al.
Partner: UNT Libraries Government Documents Department
open access

Neutron Cross Section Uncertainties in the Thermal and Resonance Regions

Description: In the 'Atlas of Neutron Resonances', special care was expended to ensure that the resonance parameter information reproduces the various measured thermal cross sections, as well as the infinite dilute resonance integrals for Z = 1-100. In contrast, the uncertainties of the recommended quantities do not match those generated from the uncertainties of the resonance parameters. To address this problem, the present study was initiated to achieve consistency for 15 actinides and 21 structural and c… more
Date: June 24, 2008
Creator: Mughabghab, S. F. & Oblozinsky, P.
Partner: UNT Libraries Government Documents Department
open access

Development of covariance capabilities in EMPIRE code

Description: The nuclear reaction code EMPIRE has been extended to provide evaluation capabilities for neutron cross section covariances in the thermal, resolved resonance, unresolved resonance and fast neutron regions. The Atlas of Neutron Resonances by Mughabghab is used as a primary source of information on uncertainties at low energies. Care is taken to ensure consistency among the resonance parameter uncertainties and those for thermal cross sections. The resulting resonance parameter covariances are f… more
Date: June 24, 2008
Creator: Herman, M.; Pigni, M. T.; Oblozinsky, P.; Mughabghab, S. F.; Mattoon, C. M.; Capote, R. et al.
Partner: UNT Libraries Government Documents Department
open access

High gain FEL amplification of charge modulation caused by a hadron

Description: In scheme of coherent electron cooling (CeC) [1,2], a modulation of electron beam density induced by a copropagation hadron is amplified in high gain FEL. The resulting amplified modulation of electron beam, its shape, form and its lethargy determine number of important properties of the coherent electron cooling. In this talk we present both analytical and numerical (using codes RON [3] and Genesis [4]) evaluations of the corresponding Green functions. We also discuss influence of electron bea… more
Date: August 24, 2008
Creator: Litvinenko, V.; Ben-Zvi, Ilan; Hao, Y.; Kayran, D.; Pozdeyev, E.; Wang, G. et al.
Partner: UNT Libraries Government Documents Department
open access

Formic Acid Dehydrogenation on Au-Based Catalysts at Near-Ambient Temperatures

Description: Formic acid (HCOOH) is a convenient hydrogen carrier in fuel cells designed for portable use. Recent studies have shown that HCOOH decomposition is catalyzed with Ru-based complexes in the aqueous phase at near-ambient temperatures. HCOOH decomposition reactions are used frequently to probe the effects of alloying and cluster size and of geometric and electronic factors in catalysis. These studies have concluded that Pt is the most active metal for HCOOH decomposition, at least as large crystal… more
Date: November 24, 2008
Creator: Ojeda, Manuel & Iglesia, Enrique
Partner: UNT Libraries Government Documents Department
open access

CP Violation in B0 decays to Charmonium and Charm Final States

Description: We report on measurements of time-dependent CP-violation asymmetries in neutral B meson decays to charmonium and charm final states. The results are obtained from a data sample of (467 {+-} 5) x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the PEP-II B factory.
Date: September 24, 2008
Creator: Chen, Chunhui
Partner: UNT Libraries Government Documents Department
open access

NUCLEAR WASTE GLASSES CONTINUOUS MELTING AND BULK VITRIFICAITON

Description: This contribution addresses various aspects of nuclear waste vitrification. Nuclear wastes have a variety of components and composition ranges. For each waste composition, the glass must be formulated to possess acceptable processing and product behavior defined in terms of physical and chemical properties that guarantee the glass can be easily made and resist environmental degradation. Glass formulation is facilitated by developing property-composition models, and the strategy of model develop… more
Date: March 24, 2008
Creator: AA, KRUGER & PR, HRMA
Partner: UNT Libraries Government Documents Department
Back to Top of Screen