The Astro-E2 XRS/EBIT Microcalorimeter XC-ray Spectrometer (open access)

The Astro-E2 XRS/EBIT Microcalorimeter XC-ray Spectrometer

The X-ray Spectrometer (XRS) instrument is a revolutionary non-dispersive spectrometer that will form the basis for the Astro-E2 observatory to be launched in 2005. We have recently installed a flight spare XRS microcalorimeter spectrometer at the EBIT-I and SuperEBIT facility at LLNL replacing the XRS from the earlier Astro-E mission and providing twice the resolving power. The XRS microcalorimeter is an x-ray detector that senses the heat deposited by the incident photon. It achieves a high energy resolution by operating at 0.06K and by carefully engineering the heat capacity and thermal conductance. The XRS/EBIT instrument has 32 pixels in a square geometry and achieves an energy resolution of 6 eV at 6 keV, with a bandpass from 0.1 to 12 keV (or more at higher operating temperature). The instrument allows detailed studies of the x-ray line emission of laboratory plasmas. The XRS/EBIT also provides an extensive calibration 'library' for the Astro-E2 observatory.
Date: April 16, 2004
Creator: Porter, F S; Brown, G V; Boyce, K R; Kelley, R L; Kilbourne, C A; Beiersdorfer, P et al.
Object Type: Article
System: The UNT Digital Library
Integration Architecture Capability Case Model (open access)

Integration Architecture Capability Case Model

None
Date: April 16, 2004
Creator: Watts, R A
Object Type: Report
System: The UNT Digital Library
Supersymmetric Froggatt-Nielsen Models with Baryon- and Lepton-Number Violation (open access)

Supersymmetric Froggatt-Nielsen Models with Baryon- and Lepton-Number Violation

We systematically investigate the embedding of U(1)_X Froggatt-Nielsen models in (four-dimensional) local supersymmetry. We restrict ourselves to models with a single flavon field. We do not impose a discrete symmetry by hand, e.g., R-parity, baryon-parity or lepton-parity. Thus we determine the order of magnitude of the baryon- and/or lepton violating coupling constants through the Froggatt-Nielsen mechanism. We then scrutinize whether the predicted coupling constants are in accord with weak or GUT scale constraints. Many models turn out to be incompatible.
Date: April 16, 2004
Creator: Dreiner, Herbi K. & Thormeier, Marc
Object Type: Article
System: The UNT Digital Library
Chemical Interactions in Multimetal/Zeolite Catalysts (open access)

Chemical Interactions in Multimetal/Zeolite Catalysts

This two-year project has led to a significant improvement in the fundamental understanding of the catalytic action of zeolite-supported redox catalysts. It turned out to be essential that we could combine four strategies for the preparation of catalysts containing transition metal (TM) ions in zeolite cavities: (1) ion exchange from aqueous solution; (2) chemical vapor deposition (CVD) of a volatile halide onto a zeolite in its acidic form; (3) solid state ion exchange; and (4) hydrothermal synthesis of a zeolite having TM ions in its lattice, followed by a treatment transporting these ions to ''guest positions''. Technique (2) enables us to position more TM ions into cavities than permitted by the conventional technique (1).viz one positive charge per Al centered tetrahedron in the zeolite lattice. The additional charge is compensated by ligands to the TM ions, for instance in oxo-ions such as (GaO){sup +} or dinuclear [Cu-O-Cu]{sup 2+}. While technique (3) is preferred over CVD where volatile halides are not available, technique (4) leads to rather isolated ''ex lattice'' oxo-ions. Such oxo-ions tend to be mono-nuclear, in contrast to technique (2) which preferentially creates dinuclear oxo-ions of the same TM element. A favorable element for the present research was that …
Date: April 16, 2004
Creator: Sachtler, Wolfgang M. H.
Object Type: Report
System: The UNT Digital Library
Toward Femtosecond X-ray Spectroscopy at the Advanced Light Source (open access)

Toward Femtosecond X-ray Spectroscopy at the Advanced Light Source

The realization of tunable, ultrashort pulse x-ray sources promises to open new venues of science and to shed new light on long-standing problems in condensed matter physics and chemistry. Fundamentally new information can now be accessed. Used in a pump-probe spectroscopy, ultrashort x-ray pulses provide a means to monitor atomic rearrangement and changes in electronic structure in condensed-matter and chemical systems on the physically-limiting time-scales of atomic motion. This opens the way for the study of fast structural dynamics and the role they play in phase transitions, chemical reactions and the emergence of exotic properties in materials with strongly interacting degrees of freedom. The ultrashort pulse x-ray source developed at the Advanced Light Source at the Lawrence Berkeley Laboratory is based on electron slicing in storage rings, and generates {approx}100 femtosecond pulses of synchrotron radiation spanning wavelengths from the far-infrared to the hard x-ray region of the electromagnetic spectrum. The tunability of the source allows for the adaptation of a broad range of static x-ray spectroscopies to useful pump-probe measurements. Initial experiments are attempted on transition metal complexes that exhibit relatively large structural changes upon photo-excitation and which have excited-state evolution determined by strongly interacting structural, electronic and magnetic degrees …
Date: April 16, 2004
Creator: Chong, Henry Herng Wei
Object Type: Thesis or Dissertation
System: The UNT Digital Library
One-Step PCR Sequencing. Final Technical Progress Report for February 15, 1997 - November 30, 2001 (open access)

One-Step PCR Sequencing. Final Technical Progress Report for February 15, 1997 - November 30, 2001

We investigated new chemistries and alternate approaches for direct gene sequencing and detection based on the properties of boron-substituted nucleotides as chain delimiters in lieu of conventional chain terminators. Chain terminators, such as the widely used Sanger dideoxynucleotide truncators, stop DNA synthesis during replication and hence are incompatible with further PCR amplification. Chain delimiters, on the other hand, are chemically-modified, ''stealth'' nucleotides that act like normal nucleotides in DNA synthesis and PCR amplification, but can be unmasked following chain extension and exponential amplification. Specifically, chain delimiters give rise to an alternative sequencing strategy based on selective degradation of DNA chains generated by PCR amplification with modified nucleotides. The method as originally devised employed template-directed enzymatic, random incorporation of small amounts of boron-modified nucleotides (e.g., 2'-deoxynucleoside 5'-alpha-[P-borano]- triphosphates) during PCR amplification. Rather than incorporation of dideoxy chain terminators, which are less efficiently incorporated in PCR-based amplification than natural deoxynucleotides, our method is based on selective incorporation and exonuclease degradation of DNA chains generated by efficient PCR amplification of chemically-modified ''stealth'' nucleotides. The stealth nucleotides have a boranophosphate group instead of a normal phosphate, yet behave like normal nucleotides during PCR-amplification. The unique feature of our method is that the position of …
Date: April 16, 2004
Creator: Shaw, B. R.
Object Type: Report
System: The UNT Digital Library
Indicators of the energy error in the Linac to Booster transfer (open access)

Indicators of the energy error in the Linac to Booster transfer

The match between the Linac beam energy and the energy determined by the bending field of the Booster magnets is crucial for rf capture, beam quality, and the transmission efficiency in a Booster cycle. The observation of the injection energy match is important for injection tuning. Several signals, such as phase shift drive (PSD), radial position error (RPOS), synchrotron phase (SPD), and fast phase error (FPERR), provide consistent information on the energy match and can be used for an injection match tuning.
Date: April 16, 2004
Creator: Yang, Xi & MacLachlan, James
Object Type: Report
System: The UNT Digital Library
Atomic and Molecular Facility at the Advanced Light Source (open access)

Atomic and Molecular Facility at the Advanced Light Source

Atomic physics research using an undulator beamline at the Advanced Light Source (ALS).
Date: April 16, 2004
Creator: Berrah, N.
Object Type: Report
System: The UNT Digital Library
YUCCA MOUNTAIN SITE DESCRIPTION (open access)

YUCCA MOUNTAIN SITE DESCRIPTION

The ''Yucca Mountain Site Description'' summarizes, in a single document, the current state of knowledge and understanding of the natural system at Yucca Mountain. It describes the geology; geochemistry; past, present, and projected future climate; regional hydrologic system; and flow and transport within the unsaturated and saturated zones at the site. In addition, it discusses factors affecting radionuclide transport, the effect of thermal loading on the natural system, and tectonic hazards. The ''Yucca Mountain Site Description'' is broad in nature. It summarizes investigations carried out as part of the Yucca Mountain Project since 1988, but it also includes work done at the site in earlier years, as well as studies performed by others. The document has been prepared under the Office of Civilian Radioactive Waste Management quality assurance program for the Yucca Mountain Project. Yucca Mountain is located in Nye County in southern Nevada. The site lies in the north-central part of the Basin and Range physiographic province, within the northernmost subprovince commonly referred to as the Great Basin. The basin and range physiography reflects the extensional tectonic regime that has affected the region during the middle and late Cenozoic Era. Yucca Mountain was initially selected for characterization, in part, …
Date: April 16, 2004
Creator: Simmons, A. M.
Object Type: Report
System: The UNT Digital Library
Applied and Environmental Microbiology Gordon Research Conference July 27 - August 1, 2003 (open access)

Applied and Environmental Microbiology Gordon Research Conference July 27 - August 1, 2003

None
Date: April 16, 2004
Creator: Wall, Judy D.
Object Type: Article
System: The UNT Digital Library
Imaging Detectors for 20-100 ke V X-ray Backlighters in HEDES Petawatt Experiments (open access)

Imaging Detectors for 20-100 ke V X-ray Backlighters in HEDES Petawatt Experiments

We are developing a petawatt laser for use as a high energy backlighter source in the 20{approx} 100 keV range. High energy x-ray backlighters will be essential for radiographing High-Energy- Density Experimental Science (HEDES) targets for NIF projects especially to probe implosions and high areal density planar samples. For these experiments we are employing two types of detectors: a columnar grown CsI scintillator coupled to a 2K x 2K CCD camera and a CdTe crystal with a special ASIC readout electronics in a 508 x 512 format array. We have characterized these sensors using radioactive sources. In addition, we utilized them to measure the Sm K{alpha} source size generated by the short pulse laser, JanUSP, at LLNL. This paper will present the results of our characterizations of these detectors.
Date: April 16, 2004
Creator: Wickersham, J E; Park, H; Bell, P M; Koch, J A; Landen, O L & Moody, J D
Object Type: Article
System: The UNT Digital Library
Probabilistic Seismic Hazard Analysis for Southern California Coastal Facilities (open access)

Probabilistic Seismic Hazard Analysis for Southern California Coastal Facilities

The overall objective of this study was to develop probabilistic seismic hazard estimates for the coastal and offshore area of Ventura, Los Angeles and Orange counties for use as a basis for the University of Southern California (USC) to develop physical models of tsunami for the coastal regions and by the California State Lands Commission (SLC) to develop regulatory standards for seismic loading and liquefaction evaluation of marine oil terminals. The probabilistic seismic hazard analysis (PSHA) was carried out by the Lawrence Livermore National Laboratory (LLNL), in several phases over a time period of two years, following the method developed by LLNL for the estimation of seismic hazards at Department Of Energy (DOE) facilities, and for 69 locations of nuclear plants in the Eastern United States, for the Nuclear Regulatory Commission (NRC). This method consists in making maximum use of all physical data (qualitative, and quantitative) and to characterize the uncertainties by using a set of alternate spatiotemporal models of occurrence of future earthquakes, as described in the SSHAC, PSHA Guidance Document (Budnitz et al., 1997), and implemented for the NRC (Savy et al., 2002). In general, estimation of seismic hazard is based not only on our understanding of the …
Date: April 16, 2004
Creator: Savy, J & Foxall, B
Object Type: Report
System: The UNT Digital Library
Progressive Compression of Volumetric Subdivision Meshes (open access)

Progressive Compression of Volumetric Subdivision Meshes

We present a progressive compression technique for volumetric subdivision meshes based on the slow growing refinement algorithm. The system is comprised of a wavelet transform followed by a progressive encoding of the resulting wavelet coefficients. We compare the efficiency of two wavelet transforms. The first transform is based on the smoothing rules used in the slow growing subdivision technique. The second transform is a generalization of lifted linear B-spline wavelets to the same multi-tier refinement structure. Direct coupling with a hierarchical coder produces progressive bit streams. Rate distortion metrics are evaluated for both wavelet transforms. We tested the practical performance of the scheme on synthetic data as well as data from laser indirect-drive fusion simulations with multiple fields per vertex. Both wavelet transforms result in high quality trade off curves and produce qualitatively good coarse representations.
Date: April 16, 2004
Creator: Laney, D & Pascucci, V
Object Type: Article
System: The UNT Digital Library
Robust Extraction and Multi-Technique Analysis of Micrometeoroids Captured in Low Earth Orbit (open access)

Robust Extraction and Multi-Technique Analysis of Micrometeoroids Captured in Low Earth Orbit

None
Date: April 16, 2004
Creator: Westphal, A.; Graham, G.; Bench, G.; Brennan, S.; Luening, K.; Pianetta, P. et al.
Object Type: Article
System: The UNT Digital Library
X-ray Spectroscopy with Elliptical Crystals and Face-On Framing Cameras (open access)

X-ray Spectroscopy with Elliptical Crystals and Face-On Framing Cameras

X-ray spectrometers using elliptically bent crystals have desirable properties for applications requiring broad spectral coverage, good spectral resolution, and minimized source broadening. Previous work used custom-positioned film or microchannel plate detectors. They find it is also useful and cost-effective to field elliptical crystals in existing snouts on the face-on gated microchannel plate framing cameras commonly used at many facilities. they numerically explored the full design space (spectral range and resolution) of elliptical crystals compatible with the new MSPEC multipurpose spectrometer snout. They have tested at the Omega laser an elliptical RAP crystal with 174 mm focal length, 0.9885 eccentricity, and 4.6 degree inclination, viewing from 1.0 to at least 1.7 keV with E/dE of 300-500. A slit (2x mag) images 3 mm sources with 70 um spatial resolution.
Date: April 16, 2004
Creator: Heeter, R.; Emig, J.; Fournier, K.; Hansen, S.; May, M. & Young, B.
Object Type: Article
System: The UNT Digital Library
RESOURCE ASSESSMENT OF THE IN-PLACE AND POTENTIALLY RECOVERABLE DEEP NATURAL GAS RESOURCE OF THE ONSHORE INTERIOR SALT BASINS, NORTH CENTRAL AND NORTHEASTERN GULF OF MEXICO (open access)

RESOURCE ASSESSMENT OF THE IN-PLACE AND POTENTIALLY RECOVERABLE DEEP NATURAL GAS RESOURCE OF THE ONSHORE INTERIOR SALT BASINS, NORTH CENTRAL AND NORTHEASTERN GULF OF MEXICO

The University of Alabama and Louisiana State University have undertaken a cooperative 3-year, advanced subsurface methodology resource assessment project, involving petroleum system identification, characterization and modeling, to facilitate exploration for a potential major source of natural gas that is deeply buried (below 15,000 feet) in the onshore interior salt basins of the North Central and Northeastern Gulf of Mexico areas. The project is designed to assist in the formulation of advanced exploration strategies for funding and maximizing the recovery from deep natural gas domestic resources at reduced costs and risks and with minimum impact. The results of the project should serve to enhance exploration efforts by domestic companies in their search for new petroleum resources, especially those deeply buried (below 15,000 feet) natural gas resources, and should support the domestic industry's endeavor to provide an increase in reliable and affordable supplies of fossil fuels. The principal research effort for Year 1 of the project is data compilation and petroleum system identification. The research focus for the first nine (9) months of Year 1 is on data compilation and for the remainder of the year the emphasis is on petroleum system identification. The objectives of the study are: to perform resource …
Date: April 16, 2004
Creator: Mancini, Ernest A.
Object Type: Report
System: The UNT Digital Library