Weekly newspaper from Timpson, Texas that includes local, state, and national news along with advertising.

The goal of demonstrating ignition on the National Ignition Facility (NIF) has motivated a revisit of double-shell (DS) targets as a complementary path to the cryogenic baseline approach. Expected benefits of DS ignition targets include non-cryogenic deuterium-tritium (DT) fuel preparation, minimal hohlraum-plasma mediated laser backscatter, low threshold ignition temperatures ({approx} 4 keV) for relaxed hohlraum x-ray flux asymmetry tolerances, and minimal (two-) shock timing requirements. On the other hand, DS ignition presents several formidable challenges, encompassing room-temperature containment of high-pressure DT ({approx} 790 atm) in the inner shell, strict concentricity requirements on the two shells (< 3 {micro}m), development of nano-porous (<100 nm) low-density (<100 mg/cc) metallic foams for structural support of the inner shell and hydrodynamic instability mitigation, and effective control of hydrodynamic instabilities on the high-Atwood number interface between the DT fuel and the high-Z inner shell. Recent progress in DS ignition designs and required materials-science advances at the nanoscale are described herein. Two new ignition designs that use rugby-shaped vacuum hohlraums are presented which utilize either 1 MJ or 2 MJ of laser energy at 3{omega}. The capability of the NIF to generate the requested reverse-ramp pulse shape for DS ignition is expected to be comparable to …

Indirectly driven double shell implosions are being investigated as a possible noncryogenic path to ignition on the National Ignition Facility. Lawrence Livermore National Laboratory has made several technological advances that have produced double shell targets that represent a significant improvement to previously fielded targets. The inner capsule is supported inside the ablator shell by SiO{sub 2} aerogel with a nominal density of 50 mg/cm{sup 3}. The aerogel is cast around the inner capsule and then machined concentric to it. The seamless sphere of aerogel containing the embedded capsule is then assembled between the two halves of the ablator shell. The concentricity between the two shells has been improved to less than 1.5 {micro}m. The ablator shell consists of two hemispherical shells that mate at a step joint that incorporates a gap with a nominal thickness of 0.1 {micro}m. Using a new flexure-based tool holder that precisely positions the diamond cutting tool on the diamond turning machine, step discontinuities on the inner surface of the ablator of less than 0.5 {micro}m have been achieved. New methods have been used to comprehensively characterize each of the targets using high-resolution x-ray imaging systems.

Daily newspaper from Perry, Oklahoma that includes local, state, and national news along with advertising.

Weekly newspaper from Canadian, Texas that includes local, state and national news along with some advertising.

Daily newspaper from Chickasha, Oklahoma that includes local, state, and national news along with advertising.

Daily newspaper from Altus, Oklahoma that includes local, state, and national news along with advertising.

Under the auspices of the research grant, the Intense Beam Theoretical Research Goup at Massachusetts Institute of Technology's Plasma Science and Fusion Center made significant contributions in a number of important areas in the HIF and HEDP research, including: (a) Derivation of rms envelope equations and study of rms envelope dynamics for high-intensity heavy ion beams in a small-aperture AG focusing transport systems; (b) Identification of a new mechanism for chaotic particle motion, halo formation, and beam loss in high-intensity heavy ion beams in a small-aperture AG focusing systems; Development of elliptic beam theory; (d) Study of Physics Issues in the Neutralization Transport Experiment (NTX).

Daily newspaper from Baytown, Texas that includes local, state, and national news along with advertising.

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Weekly newspaper from Lexington, Oklahoma that includes local, state, and national news along with advertising.

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The understanding of mutagenic potency has been primarily approached using ''quantitative structure activity relationships'' (QSAR). Often this method allows the prediction of mutagenic potency of the compound based on its structure. But it does not give the underlying reason why the mutagenic activities differ. We have taken a set of heterocyclic amine structures and used molecular dynamic calculations to dock these molecules into the active site of a computational model of the cytochrome P-450 1A1 enzyme. The calculated binding strength using Boltzman distribution constants was then compared to the QSAR value (HF/6-31G* optimized structures) and the Ames/Salmonella mutagenic potency. Further understanding will only come from knowing the complete set of mutagenic determinants. These include the nitrenium ion half-life, DNA adduct half-life, efficiency of repair of the adduct, and ultimately fixation of the mutation through cellular processes. For two isomers, PhIP and 3-Me-PhIP, we showed that for the 100-fold difference in the mutagenic potency a 5-fold difference can be accounted for by differences in the P450 oxidation. The other factor of 20 is not clearly understood but is downstream from the oxidation step. The application of QSAR (chemical characteristics) to biological principles related to mutagenesis is explored in this report.

Weekly newspaper from Sachse, Texas that includes local, state and national news along with advertising.

A study of the relevant laser-plasma interaction processes has been performed in long-scale length plasmas that emulate the plasma conditions in indirect drive inertial confinement fusion targets. Experiments in this high-temperature (T{sub e} = 3.5 keV), dense (n{sub e} = 0.5 - 1 x 10{sup -3}) hohlraum plasma have demonstrated that blue 351-nm laser beams produce less than 1% total backscatter resulting in transmission greater than 90% for ignition relevant laser intensities (I < 2 x 10{sup 15} W cm{sup -2}). The bulk plasma conditions have been independently characterized using Thomson scattering where the peak electron temperatures are shown to scale with the hohlraum heater beam energy in the range from 2 keV to 3.5 keV. This feature has allowed us to determine the thresholds for both backscattering and filamentation instabilities; the former measured with absolutely calibrated full aperture backscatter and near backscatter diagnostics and the latter with a transmitted beam diagnostics. Comparing the experimental results with detailed gain calculations for the onset of significant laser scattering processes shows that these results are relevant for the outer beams in ignition hohlraum experiments corresponding to a gain threshold for stimulated Brillouin scattering of 15. By increasing the gas fill density in …

Weekly newspaper published in Duncanville, Texas that includes local Cedar Hill, state, and national news along with advertising.

The authors present calculations describing the production of photons through multi-step processes occurring when a beam of gamma rays interacts with a macroscopic material. These processes involve the creation of energetic electrons through Compton scattering, photo-absorption and pair production, the subsequent scattering of these electrons, and the creation of energetic photons occurring as these electrons are slowed through Bremsstrahlung emission. Unlike single Compton collisions, during which an energetic photon that is scattered through a large angle loses most of its energy, these multi-step processes result in a sizable flux of energetic photons traveling at large angles relative to an incident photon beam. These multi-step processes are also a key background in experiments that measure nuclear resonance fluorescence by shining photons on a thin foil and observing the spectrum of back-scattered photons. Effective cross sections describing the production of backscattered photons are presented in a tabular form that allows simple estimates of backgrounds expected in a variety of experiments. Incident photons with energies between 0.5 MeV and 8 MeV are considered. These calculations of effective cross sections may be useful for those designing NRF experiments or systems that detect specific isotopes in well-shielded environments through observation of resonance fluorescence.

Weekly newspaper from Garber, Oklahoma that includes local, state, and national news along with advertising.

We examine the origin of recently observed variations with internuclear distance (R) of the fully differential cross sections for double ionization of aligned H2 by absorption of a single photon. Using the results of fully converged numerical solutions of the Schroedinger equation, we show that these variations arise primarily from pronounced differences in the R-dependence of the parallel and perpendicular components of the ionization amplitude. We also predict that R-dependences should be readily observable in the asymmetry parameter for photo-double ionization, even in experimental measurements that are not differential in the energy sharings between ejected photo-electrons.

Among the goals of the MINOS experiment are the test of the {nu}{sub {mu}} {yields} {nu}{sub {tau}} oscillation and the search for sub-dominant {nu}{sub {mu}} {yields} {nu}{sub {tau}} oscillations. The former proceeds by a {nu}{sub {mu}} ''disappearance'' analysis while the latter would involve the ''appearance'' of {nu}{sub e} interactions in a predominantly {nu}{sub {mu}} beam. The disappearance of muon neutrinos is described by P({nu}{sub {mu}} {yields} {mu}{sub {mu}}) = 1 - sin{sup 2} 2{theta}{sub 23} sin{sup 2} (1.27 {Delta} m{sub 23}{sup 2} L/E) in the two-flavor approximation where {theta}{sub 23} is the angle between the second row and third column of the neutrino mixing matrix, {Delta}m{sub 23}{sup 2} = m{sub 2}{sup 2}-m{sub 3}{sup 2} (eV{sup 2}), L is the neutrino flight distance in km and E is the neutrino energy in GeV. A generic disappearance experiment compares a measured muon neutrino energy spectrum at a fixed baseline to the known energy spectrum of muon neutrino beam to extract the oscillation parameters sin{sup 2} 2{theta} which controls the overall magnitude of the disappearance and {Delta}m{sup 2} which controls the energy dependence.

Weekly newspaper from Port Aransas, Texas on Mustang Island that includes local, state and national news along with extensive advertising.

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Weekly newspaper from De Leon, Texas that includes local, state, and national news along with advertising.