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Syntheses, Structure, Magnetism, and Optical Properties of Lutetium-based Interlanthanide Selenides

Description: Ln{sub 3}LuSe{sub 6} (Ln = La, Ce), {beta}-LnLuSe{sub 3} (Ln = Pr, Nd), and Ln{sub x}Lu{sub 4-x}Se{sub 6} (Ln = Sm, Gd; x = 1.82, 1.87) have been synthesized using a Sb{sub 2}Se{sub 3} flux at 1000 C. Ln{sub 3}LuSe{sub 6} (Ln = La, Ce) adopt the U{sub 3}ScS{sub 6}-type three-dimensional structure, which is constructed from two-dimensional {infinity}{sup 2} [Ln{sub 3}Se{sub 6}]{sup 3-} slabs with the gaps between these slabs filled by octahedrally coordinated Lu{sup 3+} ions. The series of {beta}-LnLuSe{sub 3} (Ln = Pr, Nd) are isotypic with UFeS{sub 3}. Their structures include layers formed from LuSe6 octahedra that are separated by eight-coordinate larger Ln{sup 3+} ions in bicapped trigonal prismatic environments. Sm{sub 1.82}Lu{sub 2.18}Se{sub 6} and Gd{sub 1.87}Lu{sub 2.13}Se{sub 6} crystallize in the disordered F-Ln{sub 2}S{sub 3} type structure with the eight-coordinate bicapped trigonal prismatic Ln(1) ions residing in the one-dimensional channels formed by three different double chains via edge and corner sharing. These double chains are constructed from Ln(2)Se{sub 7} monocapped trigonal prisms, Ln(3)Se{sub 6} octahedra, and Ln(4)S{sub 6} octahedra, respectively. The magnetic susceptibilities of {beta}-PrLuSe{sub 3} and {beta}-NdLuSe{sub 3} follow the Curie-Weiss law. Sm{sub 1.82}Lu{sub 2.18}Se{sub 6} shows van Vleck paramagnetism. Magnetic measurements show that Gd{sub 1.87}Lu{sub 2.13}Se{sub 6} undergoes an antiferromagnetic transition around 4 K. Ce{sub 3}LuSe{sub 6} exhibits ferromagnetic ordering below 5 K. The optical band gaps for La{sub 3}LuSe{sub 6}, Ce{sub 3}LuSe{sub 6}, {beta}- PrLuSe{sub 3}, {beta}-NdLuSe{sub 3}, Sm{sub 1.82}Lu{sub 2.18}Se{sub 6}, and Gd{sub 1.87}Lu{sub 2.13}Se{sub 6} are 1.26, 1.10, 1.56, 1.61, 1.51, and 1.56 eV, respectively.
Date: October 1, 2007
Creator: Booth, Corwin H; Jin, Geng Bang; Choi, Eun Sang; Guertin, Robert P.; Brooks, James S.; Booth, Corwin H. et al.
Partner: UNT Libraries Government Documents Department

Polarization selecting Optical Element using a Porro Prism Incorporating a thin film Polarizer in a single element

Description: A Porro prism and a light polarizer are combined in a single optical element termed a Hendrix Prism. The design provides retro-reflection of incoming light of a predetermined polarization in a direction anti-parallel to the direction of light incidence, while reflecting undesired light, i.e., that having a polarization orthogonal to the predetermined polarization, from the surface of the light polarizer. The undesired light is reflected in a direction that does not interfere with the intended operation of the device in which the Hendrix Prism is installed yet provides feedback to the system in which it is used.
Date: January 28, 2000
Creator: Hendrix, James lee
Partner: UNT Libraries Government Documents Department

Synthesis, structure, magnetism, and optical properties of theordered mixed-lanthanide sulfides gamma-LnLn'S3 (Ln=La, Ce; Ln'=Er, Tm,Yb)

Description: {gamma}-LnLn{prime}S{sub 3} (Ln = La, Ce; Ln{prime} = Er, Tm, Yb) have been prepared as dark red to black single crystals by the reaction of the respective lanthanides with sulfur in a Sb{sub 2}S{sub 3} flux at 1000 C. This isotypic series of compounds adopts a layered structure that consists of the smaller lanthanides (Er, Tm, and Yb) bound by sulfide in six- and seven-coordinate environments that are connected together by the larger lanthanides (La and Ce) in eight- and nine-coordinate environments. The layers can be broken down into three distinct one-dimensional substructures containing three crystallographically unique Ln{prime} centers. The first of these is constructed from one-dimensional chains of edge-sharing [Ln{prime}S{sub 7}] monocapped trigonal prisms that are joined to equivalent chains via edge-sharing to yield ribbons. There are parallel chains of [Ln{prime}S{sub 6}] distorted octahedra that are linked to the first ribbons through corner-sharing. These latter units also share corners with a one-dimensional ribbon composed of parallel chains of [Ln{prime}S{sub 6}] polyhedra that edge-share both in the direction of chain propagation and with adjacent identical chains. Magnetic susceptibility measurements show Curie-Weiss behavior from 2 to 300 K with antiferromagnetic coupling, and no evidence for magnetic ordering. The {theta}{sub p} values range from -0.4 to -37.5 K, and spin-frustration may be indicated for the Yb-containing compounds. All compounds show magnetic moments substantially reduced from those calculated for the free ions. The optical band gaps for {gamma}-LaLn{prime}S{sub 3} (Ln{prime} = Er, Tm, Yb) are approximately 1.6 eV, whereas {gamma}-CeLn{prime}S{sub 3} (Ln{prime} = Er, Tm, Yb) are approximately 1.3 eV.
Date: December 12, 2006
Creator: Jin, G.B.; Choi, E.S.; Guertin, R.P.; Brooks, J.S.; Bray, T.H.; Booth, C.H. et al.
Partner: UNT Libraries Government Documents Department

Syntheses, Structure, Magnetism, and Optical Properties of the Partial Ordered Quaternary Interlanthanide Sulfides PrLnYb2S6 (Ln = Tb, Dy)

Description: Dark red single crystals of PrLnYb{sub 2}S{sub 6} (Ln = Pr/Yb, Tb, Dy) have been synthesized through the reaction of elemental rare earth metals and S using a Sb{sub 2}S{sub 3} flux at 1000 C. These isotypic compounds adopt the F-Ln{sub 2}S3 three-dimensional open channel structure type. Eight-coordinate Pr{sup 3+} ions sit in the channels, which are constructed from three different edge-shared double chains running down the b axis, which contain Yb(1)S{sub 6} octahedra, Yb(2)S{sub 6}, octahedra and LnS{sub 7} monocapped trigonal prisms, respectively. Each double chain connects to four other neighbors by sharing vertices and edges. Considerable disordering in Ln positions was observed in single X-ray diffraction experiments only in the case of Pr/Yb. Least square refinements gave rise to the formulas of Pr{sub 1.34}Yb{sub 2.66}S{sub 6}, of PrTbYb{sub 2}S{sub 6}, and PrDyYb{sub 2}S{sub 6}, which are confirmed by the elemental analysis and magnetic susceptibility measurements. Pr1.34Yb2.66S{sub 6}, PrTbYb{sub 2}S{sub 6} and PrDyYb{sub 2}S{sub 6} are paramagnetic down to 2 K without any indications of long range magnetic ordering. The optical transitions for Pr{sub 1.34}Yb{sub 2.66}S{sub 6}, PrTbYb{sub 2}S{sub 6}, and PrDyYb{sub 2}S{sub 6} are at approximately 1.6 eV. Crystallographic data: Pr{sub 1.34}Yb{sub 2.66}S{sub 6}, monoclinic, space group P2{sub 1}/m, a = 10.960(2), b = 3.9501(8), c = 11.220(2) {angstrom}, {beta} = 108.545(3), V = 460.54(16), Z = 2; PrTbYb{sub 2}S{sub 6}, monoclinic, space group P2{sub 1}/m, a = 10.9496(10), b = 3.9429(4), c = 11.2206(10) {angstrom}, {beta} = 108.525(2), V = 459.33(7), Z = 2; PrDyYb{sub 2}S{sub 6}, monoclinic, space group P2{sub 1}/m, a = 10.9384(10), b = 3.9398(4), c = 11.2037(10) {angstrom}, {beta} = 108.612(2), V = 457.57(7), Z = 2.
Date: January 11, 2008
Creator: Booth, Corwin H; Jin, Geng Bang; Choi, Eun Sang; Guertin, Robert P.; Brooks, James S.; Bray, Travis H. et al.
Partner: UNT Libraries Government Documents Department

WORKING GROUP 1 SUMMARY FOR THE 2006 FFAG WORKSHOP AT KURRI.

Description: This paper summarizes the workshop presentations at the 2006 FFAG Workshop at KURRI related to FFAG use for muons. The particular topics covered were harmonic number jump acceleration, ionization cooling, PRISM and muon phase rotation, tracking and error analysis, and our understanding of scaling and non-scaling FFAGs.
Date: November 6, 2006
Creator: BERG,J.S.
Partner: UNT Libraries Government Documents Department

The Zintl Chemistry of the Heavy Tetrel Elements

Description: Exploration of the alkali metal/alkaline-earth metal/heavy tetrel (Sn or Pb) systems has revealed a vast array of new chemistry and novel structure types. The structures and properties of these new materials have been studied in an attempt to understand the chemistry of these and other related systems. The first phase reported is Rb{sub 4}Pb{sub 9} (K{sub 4}Pb{sub 9} type). The compound contains two different types of Pb{sub 9}{sup 4-} deltahedra, a monocapped square pyramid and a distorted tricapped trigonal prism. Both cluster geometries correspond to a nido assignment even though the tricapped trigonal prism is not the classic Wade's rules nido deltahedron expected for a monocapped square antiprism. Also, a series of compounds that contain square pyramidal Tt{sub 5} polyanions of tin and lead has been obtained in alkaline-earth or rare-earth metal-tetrel systems by direct fusion of the elements to yield Sr{sub 3}Sn{sub 5}, Ba{sub 3}Pb{sub 5}, and La{sub 3}Sn{sub 5}. These phases contain square pyramidal clusters of the tetrel elements that are weakly interlinked into chains via two types of longer intercluster interactions that are mediated by bridging cations and substantially influenced by cation size and the free electron count. Attempts at incorporating another main-group element to form heteroatomic clusters were also successful. In the case of A{sub 5}InPb{sub 8} (A = K, Rb), the compounds contain clusters composed of two Pb{sub 4} tetrahedra that are interbridged by a lone {micro}{sub 6}-In atom. The InPb{sub 8} units are weakly interlinked into sheets in the ab plane by long intercluster Pb-Pb interactions. Using As led to the formation of the compound K{sub 5}As{sub 3}Pb{sub 3} which is made up of As{sub 3}Pb{sub 3}{sup 5-} crown clusters that can be likened to a 6-atom hypho-cluster based on the tricapped trigonal parent as the closo structure. These crowns are connected via intercluster ...
Date: December 31, 2002
Creator: Corbett, John D.
Partner: UNT Libraries Government Documents Department

Efficient broadband second-harmonic generation by dispersive achromatic nonlinear conversion using only prisms

Description: Using a lossless dispersive apparatus consisting of six prisms, optimized to match a second-harmonic crystal phase-matching angle vs. wavelength to second order, we efficiently doubled tunable fundamental light near 660 nm over a range of 80 nm using a 4-mm-long type-I {beta}-Barium Borate (BBO) crystal. Another lossless set of six prisms after the crystal realigned the propagation directions of the various second-harmonic frequencies to be collinear to within 1/4 spot diameter in position and 200 {mu}rad in angle. The measured conversion efficiency of a 40-mJ, 5-ns fundamental pulse was 10%.
Date: December 1, 1997
Creator: Richman, B.A.; Bisson, S.E. & Trebino, R.
Partner: UNT Libraries Government Documents Department

Prism users guide.

Description: Prism is a ParaView plugin that simultaneously displays simulation data and material model data. This document describes its capabilities and how to use them. A demonstration of Prism is given in the first section. The second section contains more detailed notes on less obvious behavior. The third and fourth sections are specifically for Alegra and CTH users. They tell how to generate the simulation data and SESAME files and how to handle aspects of Prism use particular to each of these codes.
Date: March 1, 2012
Creator: Weirs, V. Gregory
Partner: UNT Libraries Government Documents Department

Structural properties of free-standing 50 mm diameter GaN waferswith (101_0) orientation grown on LiAlO2

Description: (10{und 1}0) GaN wafers grown on (100) face of {gamma}-LiAlO{sub 2} were studied using transmission electron microscopy. Despite good lattice matching in this heteroepitaxial system, high densities of planar structural defects in the form of stacking faults on the basal plane and networks of boundaries located on prism planes inclined to the layer/substrate interface were present in these GaN layers. In addition, significant numbers of threading dislocations were observed. High-resolution electron microscopy indicates that stacking faults present on the basal plane in these layers are of low-energy intrinsic I1type. This is consistent with diffraction contrast experiments.
Date: September 27, 2005
Creator: Jasinski, Jacek; Liliental-Weber, Zuzanna; Maruska, Herbert-Paul; Chai, Bruce H.; Hill, David W.; Chou, Mitch M.C. et al.
Partner: UNT Libraries Government Documents Department

Synthesis and Crystal Structure of a Neodymium Isopropoxide Chloride, Nd6[OCH(CH3)2]17Cl1

Description: Neodymium (III) chloride reacts with sodium isopropoxide in isopropyl alcohol to produce a complex which has been characterized by an x-ray crystal structure determination to be hexa-isopropoxy-nona({mu}{sub 2}-isopropoxy)-di-({mu}{sub 3}-isopropoxY)-({mu}{sub 6}-chloro-hexa-neodymium), Nd{sub 6}[OCH(CH{sub 3}){sub 2}]{sub 17}Cl. The pale blue crystals are monoclinic, space group P2{sub 1}/n with cell dimensions a = 24.52(2) {angstrom}, b = 22.60(2) {angstrom}, c = 14.22(1) {angstrom}, and {beta} = 101.05(5){sup o}; for four molecules in the unit cell the calculated density is 1.636 gm/cc. The structure was refined by full-matrix least-squares to a conventional R factor of 0.076 for 2327 data with I > 2{sigma}. The six neodymium atoms form a trigonal prism centered about the chloride atom. Six isopropoxide groups are terminal, nine are edge bridging, and two are bridging a trigonal face of the prism yielding six two-coordinate, nine three-coordinate, and two four-coordinate oxygen atoms, respectively. The average Nd-Cl distance is 3.05(1) {angstrom}. The average Nd-O distances for oxygen atoms which are bonded to one, two, and three Nd atoms are 2.05(2) {angstrom}, 2.36(4) {angstrom}, and 2.45(5) {angstrom}, respectively.
Date: December 1, 1977
Creator: Andersen, R. A.; Templeton, D. H. & Zalkin, A.
Partner: UNT Libraries Government Documents Department

Beamsplitting using self-imaging

Description: The production of a variable array of optical point sources from a single point source can be achieved through the self-imaging properties inherent in a rectangular waveguide. Two prototype devices, based upon this concept, were designed and constructed. The resulting output patterns are discussed along with future design considerations and applications.
Date: August 7, 1996
Creator: Earl, D.D.; Allison, S.W.; Vo Dinh, T.; Alarie, J.P.; Hueber, D.; Landis, D.A. et al.
Partner: UNT Libraries Government Documents Department

Computational economy improvements in PRISM

Description: The PRISM piecewise solution mapping procedure, in which the solution of the chemical kinetic ODE system is parameterized with quadratic polynomials, is applied to CFD simulations of H{sub 2}+air combustion. Initial cost of polynomial construction is expensive, but it is recouped as the polynomial is reused. We present two methods that help us to parameterize only in places that will ultimately have high reuse. We also implement non-orthogonal Gosset factorial designs, that reduce polynomial construction costs by a factor of two over previously used orthogonal factorial designs.
Date: January 29, 2003
Creator: Tonse, Shaheen R. & Brown, Nancy J.
Partner: UNT Libraries Government Documents Department

ELECTRON MICROSCOPY OF SOME RARE EARTH-COBALT ALLOY MAGNETS

Description: Transmission electron microscopy is being used to characterize the microstructural features in some 1:5 and 2:17 RE-Co magnets. In 2:17 compounds containing Fe and Mn, lamellae of hexagonal and other po1ytypic regions embedded in the rhombohedral matrix are observed. It is shown that the interface between the hexagonal and rhombohedral phases can be described as a stacking fault with fault vector normal to the interfacial plane. APB's parallel to the prism planes in the rhombohedral structure have also been identified and characterized. In contrast, no planar faults have been observed in the 1:5 materials containing misch metal as the major rare-earth component. In these alloys extensive twinning and precipitation of a 2:17 rhombohedral phase are the major microstructural features observed. The influence of these microstructures on the magnetic properties are discussed.
Date: October 1, 1977
Creator: Mishra, R. K. & Thomas, G.
Partner: UNT Libraries Government Documents Department

Orientation dependence and bonding during pitting corrosion of HCP metals.

Description: The orientation dependence of pitting in single crystal beryllium (Be) is compared to the observations for single crystal zinc (Zn) reported by other investigators. The pit walls in stable propagating pits for prism planes were always square; in the (ioio) surface the walls were normal to the [0001] and [{bar 1}2{bar 1}0] directions while in the (110) surface the walls were normal to the [0001] and [{bar 1}100] directions. In addition, for the (ioio) and (11{bar 2}0) surfaces the pit interiors were characterized by crystallographically oriented parallel plates of unattacked Be. The orientation of these lamella was quite different than those observed in Zn. To explain this difference, the electron density distributions in the metal lattices are analyzed. A conceptual model for crystallographic pitting is introduced. In this model it is proposed that the crystallographic pits observed in single crystal hcp metals reflects the bond energy in the lattice.
Date: January 1, 2002
Creator: Lillard, Robert Scott
Partner: UNT Libraries Government Documents Department

Advanced High-Temperature Reactor for Production of Electricity and Hydrogen: Molten-Salt-Coolant, Graphite-Coated-Particle-Fuel

Description: The objective of the Advanced High-Temperature Reactor (AHTR) is to provide the very high temperatures necessary to enable low-cost (1) efficient thermochemical production of hydrogen and (2) efficient production of electricity. The proposed AHTR uses coated-particle graphite fuel similar to the fuel used in modular high-temperature gas-cooled reactors (MHTGRs), such as the General Atomics gas turbine-modular helium reactor (GT-MHR). However, unlike the MHTGRs, the AHTR uses a molten salt coolant with a pool configuration, similar to that of the PRISM liquid metal reactor. A multi-reheat helium Brayton (gas-turbine) cycle, with efficiencies >50%, is used to produce electricity. This approach (1) minimizes requirements for new technology development and (2) results in an advanced reactor concept that operates at essentially ambient pressures and at very high temperatures. The low-pressure molten-salt coolant, with its high heat capacity and natural circulation heat transfer capability, creates the potential for (1) exceptionally robust safety (including passive decay-heat removal) and (2) allows scaling to large reactor sizes [{approx}1000 Mw(e)] with passive safety systems to provide the potential for improved economics.
Date: February 21, 2002
Creator: Forsberg, C.W.
Partner: UNT Libraries Government Documents Department

Wedge Prism for Direction Resolved Speckle Correlation Interferometry

Description: The role of a wedge prism for strain sign determination and enhancing the sensitivity for sub-fringe changes is emphasized. The design and incorporation aspects for in-plane sensitive interferometers have been described in detail. Some experimental results dealing with stress determination by laser annealing and speckle corelation interferometry are presented. The prism can also be applied to produce standardized carrier fringes in spatial phase shifting interferometry.
Date: January 20, 1999
Creator: Pechersky, M.J.
Partner: UNT Libraries Government Documents Department

Structural studies of two novel La-Sn compounds: La30Sn30 and La32Ni2Sn35

Description: Two novel intermetallic compounds containing lanthanum and tin have been obtained for the first time. Single crystal structures of these two phases, La{sub 30}Sn{sub 30} and La{sub 32}Ni{sub 2}Sn{sub 35} have been studied by X-ray crystallography. La{sub 30}Sn{sub 30} is a new 1:1 binary containing La and Sn and has been refined in the Cmmm space group. This phase was made at high temperatures (<1200 C) from a loaded composition of La{sub 68}Sn{sub 70}. Unlike the reported 1:1 binary, LaSn which crystallizes in the Cmcm space group (only powder X-ray diffraction studies reported), La{sub 30}Sn{sub 30} forms good crystals for structural determination. The crystal structure of La{sub 30}Sn{sub 30} show Sn-Sn dimers and Sn-centered, face-sharing biaugmented triangular prisms composed of La atoms. La{sub 30}Sn{sub 30} does not belong to any known structure-type. La{sub 32}Ni{sub 2}Sn{sub 35} was obtained in high yields at high temperatures (> 1200 C) and refined in the 14/mmm space group. It belongs to the USi structure type in which the Ni/Sn atoms occupy the Si sites, and La/Sn atoms occupy the U sites. The crystal structure of La{sub 32}Ni{sub 2}Sn{sub 35} consists of buckled sheets made from La-centered, corner-shared octahedra of Sn. These sheets are intraconnected through Ni-Sn-Ni bonds along the c-axis. The crystals are not air sensitive, unlike La{sub 30}Sn{sub 30}, which can be attributed to the presence of Ni in the crystal structure.
Date: May 1, 2005
Creator: Yang, Amie S.
Partner: UNT Libraries Government Documents Department

Scaling and efficiency of PRISM in adaptive simulations of turbulent premixed flames

Description: The dominant computational cost in modeling turbulent combustion phenomena numerically with high fidelity chemical mechanisms is the time required to solve the ordinary differential equations associated with chemical kinetics. One approach to reducing that computational cost is to develop an inexpensive surrogate model that accurately represents evolution of chemical kinetics. One such approach, PRISM, develops a polynomial representation of the chemistry evolution in a local region of chemical composition space. This representation is then stored for later use. As the computation proceeds, the chemistry evolution for other points within the same region are computed by evaluating these polynomials instead of calling an ordinary differential equation solver. If initial data for advancing the chemistry is encountered that is not in any region for which a polynomial is defined, the methodology dynamically samples that region and constructs a new representation for that region. The utility of this approach is determined by the size of the regions over which the representation provides a good approximation to the kinetics and the number of these regions that are necessary to model the subset of composition space that is active during a simulation. In this paper, we assess the PRISM methodology in the context of a turbulent premixed flame in two dimensions. We consider a range of turbulent intensities ranging from weak turbulence that has little effect on the flame to strong turbulence that tears pockets of burning fluid from the main flame. For each case, we explore a range of sizes for the local regions and determine the scaling behavior as a function of region size and turbulent intensity.
Date: December 1, 1999
Creator: Tonse, Shaheen R.; Bell, J.B.; Brown, N.J.; Day, M.S.; Frenklach, M.; Grcar, J.F. et al.
Partner: UNT Libraries Government Documents Department

Enhanced Oil Recovery with Downhole Vibration Stimulation in Osage County, Oklahoma

Description: This Technical Quarterly Report is for the reporting period March 31, 2002 to June 30, 2002. The report provides details of the work done on the project entitled ''Enhanced Oil Recovery with Downhole Vibration Stimulation in Osage County Oklahoma''. The project is divided into nine separate tasks. Several of the tasks are being worked on simultaneously, while other tasks are dependent on earlier tasks being completed. The vibration stimulation Well 111-W-27 is located in section 8 T26N R6E of the North Burbank Unit (NBU), Osage County Oklahoma. It was drilled to 3090-feet cored, logged, cased and cemented. The rig moved off August 6, 2001. Phillips Petroleum Co. has performed several core studies on the cores recovered from the test well. Standard porosity, permeability and saturation measurements have been conducted. In addition Phillips has prepared a Core Petrology Report, detailing the lithology, stratigraphy and sedimentology for Well 111-W27, NBU. Phillips has also conducted the sonic stimulation core tests, the final sonic stimulation report has not yet been released. Calumet Oil Company, the operator of the NBU, began collecting both production and injection wells information to establish a baseline for the project in the pilot field test area since May 2001. The original 7-inch Downhole Vibration Tool (DHVT) has been thoroughly tested and it has been concluded that it needs to be redesigned. An engineering firm from Fayetteville AR has been retained to assist in developing a new design for the DHVT. The project participants requested from the DOE, a no-cost extension for the project through December 31, 2002. The no-cost extension amendment to the contract was signed during this reporting period. A technical paper SPE 75254 ''Enhanced Oil Recovery with Downhole Vibration Stimulation, Osage County, Oklahoma'' was presented at the 2002 SPE/DOE Thirteenth Symposium on Improved Oil Recovery, in Tulsa OK, ...
Date: June 30, 2002
Creator: Brett, J. Ford & Westermark, Robert V.
Partner: UNT Libraries Government Documents Department

Origin of Mineral Springs on the East Coast, North Island, NZ

Description: Strongly mineralized waters emerge as warm and cold springs from parts of a Cenozoic accretionary prism which extends along the East Coast of the North Island. The chemistry of these waters is consistent with them having been derived from connate sea water in deeply-buried marine sediments and is distinct from springs in other parts of the prism and elsewhere in New Zealand. Most of these mineral springs are associated with three, long-wavelength, magnetic anomalies which modeling suggests are caused by deeply-buried ophiolite bodies within the prism or by seamounts on the top of the subducted Pacific Plate underlying the prism. It is postulated that these deep-seated bodies have facilitated the dewatering of marine sediments from deep within the prism or from the subducted plate. This ''devolved sea water'' has then risen, been modified by contact with overlying sediments and mixed with near-surface meteoric waters, before emerging at the mineral springs.
Date: January 1, 1995
Creator: Hunt, T.M. & Glover, R.B.
Partner: UNT Libraries Government Documents Department

XI UV Laser Trigger System

Description: The X1 accelerator project at Sandia National Laboratory/New Mexico utilizes SF6 insulated, multi-stage, UV laser triggered gas switches. A 265 nm UV laser system was designed and built to generate eight simultaneous output pulses of 10 mJ each with a 13 nsec pulse width. A 1061 nm solid-state Nd:Cr:GSGG laser was frequency quadrupled using a two-stage doubling process. The 1061 nm fundamental laser energy was frequency doubled with a KTP crystal to 530 nm, achieving 65% conversion efficiency. The 530 nm output was frequency doubled with KD*P crystal to 265 nm, achieving conversion efficiency of 31%. The 265 nm beam pulse was split into eight parallel channels with a system of partially reflecting mirrors. Low timing jitter and stable energy output were achieved. The entire optical system was packaged into a rugged, o-ring sealed, aluminum structure 10''x19''x2.75''. The size of the electronics was 12''x8''x8''. Subsequent accelerator system requirements dictated a redesign of the triggering system for an output beam with less angular divergence. An unstable, crossed porro prism resonator was designed and incorporated into the system. The beam divergence of the redesigned system was successfully decreased to 0.97 mrad in the UV. The resulting frequency doubling efficiencies were 55% to 530 nm and 25% to 265 nm. The optical output remained at 10 mJ in each channel with an 11 nsec pulse width.
Date: January 26, 1999
Creator: Brickeen, B.K.; Morelli, G.L.; Paiva, R.A.; Powell, C.A. & Sundvold, P.D.
Partner: UNT Libraries Government Documents Department

Optical Alignment Techniques for Line-Imaging Velocity Interferometry and Line-Imaging Self-Emission of Targets at the National Ignition Facility (NIF)

Description: The National Ignition Facility (NIF) requires optical diagnostics for measuring shock velocities in shock physics experiments. The nature of the NIF facility requires the alignment of complex three-dimensional optical systems of very long distances. Access to the alignment mechanisms can be limited, and any alignment system must be operator friendly. The Velocity Interferometer System for Any Reflector measures shock velocities, shock breakout times, and emission of 1- to 5-mm targets at a location remote to the NIF target chamber. Three optical systems using the same vacuum chamber port each have a total track of 21 meters. All optical lenses are on kinematic mounts or sliding rails, enabling pointing accuracy of the optical axis to be checked. Counter-propagating laser beams (orange and red) align these diagnostics to a listing of tolerances. Movable aperture cards, placed before and after lens groups, show the spread of alignment spots created by the orange and red alignment lasers. Optical elements include 1-in. to 15-in. diameter mirrors, lenses with up to 10.5-in. diameters, beamsplitters, etalons, dove prisms, filters, and pellicles. Alignment of more than 75 optical elements must be verified before each target shot. Archived images from eight alignment cameras prove proper alignment before each shot.
Date: July 31, 2007
Creator: Malone, R M; Celeste, J R; Celliers, P M; Frogget, B .; Guyton, R L; Kaufman, M I et al.
Partner: UNT Libraries Government Documents Department

MANAGING UNCERTAINTIES ASSOCIATED WITH RADIOACTIVE WASTE DISPOSAL: TASK GROUP 4 OF THE IAEA PRISM PROJECT

Description: It is widely recognized that the results of safety assessment calculations provide an important contribution to the safety arguments for a disposal facility, but cannot in themselves adequately demonstrate the safety of the disposal system. The safety assessment and a broader range of arguments and activities need to be considered holistically to justify radioactive waste disposal at any particular site. Many programs are therefore moving towards the production of what has become known as a Safety Case, which includes all of the different activities that are conducted to demonstrate the safety of a disposal concept. Recognizing the growing interest in the concept of a Safety Case, the International Atomic Energy Agency (IAEA) is undertaking an intercomparison and harmonization project called PRISM (Practical Illustration and use of the Safety Case Concept in the Management of Near-surface Disposal). The PRISM project is organized into four Task Groups that address key aspects of the Safety Case concept: Task Group 1 - Understanding the Safety Case; Task Group 2 - Disposal facility design; Task Group 3 - Managing waste acceptance; and Task Group 4 - Managing uncertainty. This paper addresses the work of Task Group 4, which is investigating approaches for managing the uncertainties associated with near-surface disposal of radioactive waste and their consideration in the context of the Safety Case. Emphasis is placed on identifying a wide variety of approaches that can and have been used to manage different types of uncertainties, especially non-quantitative approaches that have not received as much attention in previous IAEA projects. This paper includes discussions of the current results of work on the task on managing uncertainty, including: the different circumstances being considered, the sources/types of uncertainties being addressed and some initial proposals for approaches that can be used to manage different types of uncertainties.
Date: March 2, 2011
Creator: Seitz, R.
Partner: UNT Libraries Government Documents Department