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Local Measurement of Electron Density and Temperature in High Temperature Laser Plasma Using the Ion-Acoustic Dispersion (open access)

Local Measurement of Electron Density and Temperature in High Temperature Laser Plasma Using the Ion-Acoustic Dispersion

The dispersion of ion-acoustic fluctuations has been measured using a novel technique that employs multiple color Thomson-scattering diagnostics to measure the frequency spectrum for two separate thermal ion-acoustic fluctuations with significantly different wave vectors. The plasma fluctuations are shown to become dispersive with increasing electron temperature. We demonstrate that this technique allows a time resolved local measurement of electron density and temperature in inertial confinement fusion plasmas.
Date: September 20, 2005
Creator: Froula, D H; Davis, P; Ross, S; Meezan, N; Divol, L; Price, D et al.
System: The UNT Digital Library
Discrete Particle Noise in Particle-in-Cell Simulations of Plasma Microturbulence (open access)

Discrete Particle Noise in Particle-in-Cell Simulations of Plasma Microturbulence

None
Date: September 20, 2005
Creator: Nevins, W. M.; Hammett, G. W.; Dimits, A. M.; Dorland, W. & Shumaker, D E
System: The UNT Digital Library
Proceedings of the 27th Seismic Research Review: Ground-Based Nuclear Explosion Monitoring Technologies (open access)

Proceedings of the 27th Seismic Research Review: Ground-Based Nuclear Explosion Monitoring Technologies

These proceedings contain papers prepared for the 27th Seismic Research Review: Ground-Based Nuclear Explosion Monitoring Technologies, held 20-22 September, 2005 in Rancho Mirage, California. These papers represent the combined research related to ground-based nuclear explosion monitoring funded by the National Nuclear Security Administration (NNSA), Air Force Technical Applications Center (AFTAC), Air Force Research Laboratory (AFRL), US Army Space and Missile Defense Command, and other invited sponsors. The scientific objectives of the research are to improve the United States capability to detect, locate, and identify nuclear explosions. The purpose of the meeting is to provide the sponsoring agencies, as well as potential users, an opportunity to review research accomplished during the preceding year and to discuss areas of investigation for the coming year. For the researchers, it provides a forum for the exchange of scientific information toward achieving program goals, and an opportunity to discuss results and future plans. Paper topics include: seismic regionalization and calibration; detection and location of sources; wave propagation from source to receiver; the nature of seismic sources, including mining practices; hydroacoustic, infrasound, and radionuclide methods; on-site inspection; and data processing.
Date: September 20, 2005
Creator: Wetovsky, Marvin A.; Benson, Jody & Patterson, Eileen F.
System: The UNT Digital Library
Tomographic reconstruction of high energy density plasmas with picosecond temporal resolution (open access)

Tomographic reconstruction of high energy density plasmas with picosecond temporal resolution

Three-dimensional reconstruction of the electron density in a plasma can be obtained by passing multiple beams at different field angles simultaneously through a plasma and performing a tomographic reconstruction of the measured field-dependent phase profiles. In this letter, a relatively simple experimental setup is proposed and simulations are carried out to verify the technique. The plasma distribution is modeled as a discreet number of phase screens and a Zernike polynomial representation of the phase screens is used to reconstruct the plasma profile. Using a subpicosecond laser, the complete three-dimensional electron density of the plasma can be obtained with a time resolution limited only by the transit time of the probe through the plasma.
Date: September 20, 2005
Creator: Baker, K L
System: The UNT Digital Library
Effect of Te Precipitates on the Performance of CdZnTe Detectors. (open access)

Effect of Te Precipitates on the Performance of CdZnTe Detectors.

A recent study of long-drift CdZnTe (CZT) Frisch-ring detectors showed that fluctuations of the collected charge (and device response) depend on the device dimensions and the concentration of Te precipitates in the material. This observation, which could be explained as the cumulative effect of precipitates, led to the investigation of thin (1 mm) planar detectors, where the effects of precipitates can be more clearly ascertained. To perform the investigation, a measurement facility was developed that allowed for high-resolution spatial mapping of the performance of CZT devices. New measurements emerging from this facility provided the first detailed comparisons of the micro-scale X-ray maps and infrared microscopy images for thin CZT samples. Analysis of the data showed conclusively that local deteriorations of device response fully correlate with Te precipitates seen in the IR images. Effects of surface processing conditions on the detector response were also clearly observed.
Date: September 20, 2005
Creator: Carini, G. A.; Bolotnikov, A. E.; Camarda, G. S.; Wright, G. W.; Li, L. & James, R. B.
System: The UNT Digital Library
Role of Diamond Secondary Emitters in High Brightness Electron Sources. (open access)

Role of Diamond Secondary Emitters in High Brightness Electron Sources.

In this paper we explore the possibility of using diamond secondary emitter in a high average current electron injector to amplify the current from the photocathode and to isolate the cathode and the injector from each other to increase the life time of the cathode and preserve the performance of the injector. Secondary electron yield of 225 and current density of 0.8 a/cm{sup 2} have been measured in the transmission mode from type 2 a natural diamond. Although the diamond will be heated during normal operation in the injector, calculations indicate that by cryogenically cooling the diamond, the temperature gradient along the diamond can be maintained within the acceptable range. The electron energy and temporal distributions are expected to be narrow from this device resulting in high brightness beams. Plans are underway to measure the SEY in emission mode, fabricate photocathode-diamond capsule and test diamond and capsule in superconducting RF injector.
Date: September 20, 2005
Creator: Rao, T.; Ben-Zvi, Ilan; Burrill, A.; Chang, X.; Grimes, J.; Rank, J. et al.
System: The UNT Digital Library
Solubilities of Solutes in Ionic Liquids from a SimplePerturbed-Hard-Sphere Theory (open access)

Solubilities of Solutes in Ionic Liquids from a SimplePerturbed-Hard-Sphere Theory

In recent years, several publications have provided solubilities of ordinary gases and liquids in ionic liquids. This work reports an initial attempt to correlate the experimental data using a perturbed-hard-sphere theory; the perturbation is based on well-known molecular physics when the solution is considered as a dielectric continuum. For this correlation, the most important input parameters are hard-sphere diameters of the solute and of the cation and anion that constitute the ionic liquid. In addition, the correlation uses the solvent density and the solute's polarizability and dipole and quadrupole moments, if any. Dispersion-energy parameters are obtained from global correlation of solubility data. Results are given for twenty solutes in several ionic liquids at normal temperatures; in addition, some results are given for gases in two molten salts at very high temperatures. Because the theory used here is much simplified, and because experimental uncertainties (especially for gaseous solutes) are often large, the accuracy of the correlation presented here is not high; in general, predicted solubilities (Henry's constants) agree with experiment to within roughly {+-} 70%. As more reliable experimental data become available, modifications in the characterizing parameters are likely to improve accuracy. Nevertheless, even in its present form, the correlation may …
Date: September 20, 2005
Creator: Qin, Yuan & Prausnitz, John M.
System: The UNT Digital Library
Efficient Modeling of PIN Diode Switches Employing Time-Domain Electromagnetic-Physics-Based Simulators (open access)

Efficient Modeling of PIN Diode Switches Employing Time-Domain Electromagnetic-Physics-Based Simulators

This paper presents an efficient full-wave time-domain simulator for accurate modeling of PIN diode switches. An equivalent circuit of the PIN diode is extracted under different bias conditions using a drift-diffusion physical model. Net recombination is modeled using a Shockley-Read-Hall process, while generation is assumed to be dominated by impact ionization. The device physics is coupled to Maxwell's equations using extended-FDTD formulism. A complete set of results is presented for the on and off states of the PIN switch. The results are validated through comparison with independent measurements, where good agreement is observed. Using this modeling approach, it is demonstrated that one can efficiently optimize PIN switches for better performance.
Date: September 20, 2005
Creator: Hussein, Y. A.; Spencer, J. E.; El-Ghazaly, S. M. & Goodnick, S. M.
System: The UNT Digital Library
Use and Misuse of Chemical Reactivity Spreadsheets (open access)

Use and Misuse of Chemical Reactivity Spreadsheets

Misidentifying chemical hazards can have serious deleterious effects. Consequences of not identifying a chemical are obvious and include fires, explosions, injury to workers, etc. Consequences of identifying hazards that are really not present can be equally as bad. Misidentifying hazards can result in increased work with loss of productivity, increased expenses, utilization/consumption of scarce resources, and the potential to modify the work to include chemicals or processes that are actually more hazardous than those originally proposed. For these reasons, accurate hazard identification is critical to any safety program. Hazard identification in the world of chemistry is, at best, a daunting task. The knowing or understanding, of the reactions between any of approximately twelve million known chemicals that may be hazardous, is the reason for this task being so arduous. Other variables, such as adding other reactants/contaminants or changing conditions (e.g., temperature, pressure, or concentration), make hazard determination something many would construe as being more than impossibly difficult. Despite these complexities, people who do not have an extensive background in the chemical sciences can be called upon to perform chemical hazard identification. Because hazard identification in the area of chemical safety is so burdensome and because people with a wide variety …
Date: September 20, 2005
Creator: Simmons, F
System: The UNT Digital Library
Small Sample Whole-Genome Amplification (open access)

Small Sample Whole-Genome Amplification

Many challenges arise when trying to amplify and analyze human samples collected in the field due to limitations in sample quantity, and contamination of the starting material. Tests such as DNA fingerprinting and mitochondrial typing require a certain sample size and are carried out in large volume reactions; in cases where insufficient sample is present whole genome amplification (WGA) can be used. WGA allows very small quantities of DNA to be amplified in a way that enables subsequent DNA-based tests to be performed. A limiting step to WGA is sample preparation. To minimize the necessary sample size, we have developed two modifications of WGA: the first allows for an increase in amplified product from small, nanoscale, purified samples with the use of carrier DNA while the second is a single-step method for cleaning and amplifying samples all in one column. Conventional DNA cleanup involves binding the DNA to silica, washing away impurities, and then releasing the DNA for subsequent testing. We have eliminated losses associated with incomplete sample release, thereby decreasing the required amount of starting template for DNA testing. Both techniques address the limitations of sample size by providing ample copies of genomic samples. Carrier DNA, included in our …
Date: September 20, 2005
Creator: Hara, C A; Nguyen, C P; Wheeler, E K; Sorensen, K J; Arroyo, E S; Vrankovich, G P et al.
System: The UNT Digital Library
RADIOLYSIS EFFECT ON WASTEFORM CORROSION (open access)

RADIOLYSIS EFFECT ON WASTEFORM CORROSION

None
Date: September 20, 2005
Creator: Kline, A.
System: The UNT Digital Library
Results from the BABAR Fully Inclusive Measurement of B? Xs? (open access)

Results from the BABAR Fully Inclusive Measurement of B? Xs?

We present preliminary results from a lepton-tagged fully-inclusive measurement of B {yields} X{sub s}{gamma} decays, where X{sub s} is any strange hadronic state. Results are based on a BABAR data set of 88.5 million B{bar B} pairs at the {Upsilon}(4S) resonance. We present a reconstructed photon energy spectrum in the {Upsilon}(4S) frame, and partial branching fractions above minimum reconstructed photon energies of 1.9, 2.0, 2.1 and 2.2 GeV. We then convert these to measurements of partial branching fractions and truncated first and second moments of the true photon energy distribution in the B rest frame, above the same minimum photon energy values. The full correlation matrices between the first and second moments are included to allow fitting to any parameterized theoretical calculation. We also measure the direct CP asymmetry {Alpha}{sub CP}(B {yields} X{sub s+d{gamma}}) (based on the charge of the tagging lepton) above a reconstructed photon energy of 2.2 GeV.
Date: September 20, 2005
Creator: Aubert, B.; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P. et al.
System: The UNT Digital Library
Measurement of Time-dependent CP-Violating Asymmetries in B0 -> K+K-K0L Decays (open access)

Measurement of Time-dependent CP-Violating Asymmetries in B0 -> K+K-K0L Decays

The authors present preliminary measurements of the Cp asymmetry parameters and CP content in B{sup 0} {yields} K{sup +}K{sup -}K{sub L}{sup 0} decays, with B{sup 0} {yields} {phi}K{sub L}{sup 0} events excluded. In a sample of 227 M B{bar B} pairs collected by the BABAR detector at the PEP-II B Factory at SLAC, they find the CP parameters to be S = 0.07 {+-} 0.28(stat){sub -0.12}{sup +0.11}(syst); C = 0.54 {+-} 0.22(stat){sub -0.09}{sup +0.08}(syst) where the first error is statistical and the second is systematic. Estimating the fraction of CP-odd final states from angular moments analysis in the K{sup +}K{sup -}K{sub S}{sup 0} CP-conjugate final state, f{sub odd}(K{sup +}K{sup -}K{sub L}{sup 0}) = 0.92 {+-} 0.07(stat) {+-} 0.06(syst), they determine sin2{beta}{sub eff} = 0.09 {+-} 0.33(stat){sub -0.14}{sup +0.13}(syst) {+-} 0.10(syst CP-cont) where the last error is due to uncertainty on the CP content.
Date: September 20, 2005
Creator: Aubert, B.; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P. et al.
System: The UNT Digital Library