We have demonstrated a simple experimental technique that can be used to measure the nonlinear absorption coefficients in glasses. We determine BK7, UG1, and UG11 glasses to have linear absorption coefficients of 0.0217 {+-} 10% cm{sup -1}, 1.7 {+-} 10% cm{sup -1}, and 0.82 {+-} 10% cm{sup -1}, respectively, two-photon absorption cross-sections of 0.025 {+-} 20% cm/GW, 0.035 {+-} 20% cm/GW, and 0.047 {+-} 20% cm/GW, respectively, excited-state absorption cross-sections of 8.0 x 10{sup -18} {+-} 20% cm{sup 2}, 2.8 x 10{sup -16} {+-} 20% cm{sup 2}, and 5 x 10{sup -17} {+-} 20% cm{sup 2}, respectively, and solarization coefficients of 8.5 x 10{sup -20} {+-} 20% cm{sup 2}, 2.5 x 10{sup -18} {+-} 20% cm{sup 2}, and 1.3 x 10{sup -19} {+-} 20% cm{sup 2}, respectively. For our application, nonlinear effects in 10-cm of BK7 are small ({le} 2%) for 355-nm fluences < 0.2 J/cm{sup 2} for flat-top pulses. However, nonlinear effects are noticeable for 355-nm fluences at 0.8 J/cm{sup 2}. In particular, we determine a 20% increase in the instantaneous absorption from linear, a solarization rate of 4% per 100 shots, and a 10% temporal droop introduced in the pulse, for 355-nm flat-top pulses at a fluence of …

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This document contains descriptions of Federal Manufacturing & Technologies (FM&T) Metrology capabilities, traceability flow charts, and the measurement uncertainty of each measurement capability. Metrology provides NIST traceable precision measurements or equipment calibration for a wide variety of parameters, ranges, and state-of-the-art uncertainties. Metrology laboratories conform to the requirements of the Department of Energy Development and Production Manual Chapter 8.4, ANSI/ISO/IEC ANSI/ISO/IEC 17025:2000, and ANSI/NCSL Z540-1 (equivalent to ISO Guide 25). FM&T Metrology laboratories are accredited by NVLAP for the parameters, ranges, and uncertainties listed in the specific scope of accreditation under NVLAP Lab code 200108-0. See the Internet at http://ts.nist.gov/ts/htdocs/210/214/scopes/2001080.pdf. These parameters are summarized in the table at the bottom of this introduction.

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During the past years, the Co-PI's have been responsible for the development and operation of optical techniques (Raman, IR, fluorescence, absorption and reflectance spectroscopy at ultrahigh pressures and high and low temperatures) which have proven to be extremely powerful for studying low-Z, molecular solids including hydrogen, ice, etc. (see results below). Meanwhile, it has become increasingly clear that optical spectroscopy has an equally extraordinary potential for studying metals and superconductors at ultrahigh pressures, thus the result will have a major impact on material research. However, because of the extreme difference in optical properties of opaque metals and transparent insulating molecular solids, successful accomplishment of the present project will require substantial effort in improving the present equipment and developing new techniques, and funds for this are requested here. Below we provide a short description of the work done and techniques developed during the last years. We also propose to explore new frontiers in compressed materials close to the insulator-metal boundaries, spin-crossover, and other quantum critical points.

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A process whereby laser-initiated surface damage on KDP/DKDP optics is removed by spot micro-machining using a high-speed drill and a single-crystal diamond bit, is shown to mitigate damage growth for subsequent laser shots. Our tests show that machined dimples on both surfaces of an AR coated doubler (KDP) crystal are stable, for 526nm, {approx} 3.2ns pulses at {approx} 12J/cm{sup 2} fluences. Other tests also confirmed that the machined dimples on both surfaces of an AR coated tripler (DKDP) crystal are stable, for 351nm, {approx} 3ns pulses at {approx} 8J/cm{sup 2}. We have demonstrated successful mitigation of laser-initiated surface damage sites as large as 0.14mm diameter on DKDP, for up to 1000 shots at 351nm, 13J/cm{sup 2}, {approx} 11ns pulse length, and up to 10 shots at 351nm, 8J/cm{sup 2}, 3ns. Details of the method are presented, including estimates for the heat generated during micro-machining and a plan to implement this method to treat pre-initiated or retrieved-from-service, large-scale optics for use in high-peak-power laser applications.

Evaluation of solute diffusion in unsaturated porous gravel is very important for investigations of contaminant transport and remediation, risk assessment, and waste disposal (e.g., the potential high-level nuclear waste repository at Yucca Mountain, Nevada). For a porous aggregate medium such as granular tuff, the total water content is comprised of surface water and interior water. The surface water component (water film around grains and pendular water between the grain contacts) could serve as a predominant diffusion pathway. To investigate the extent of surface water films and contact points affect solute diffusion in unsaturated gravel, we examined the configuration of water using x-ray computed tomography in partially saturated gravel, and made quantitative measurements of diffusion at multiple water contents using two different techniques. In the first, diffusion coefficients of potassium chloride in 2-4 mm granular tuff at multiple water contents are calculated from electrical conductivity measurements using the Nernst-Einstein equation. In the second, we used laser ablation with inductively coupled plasma-mass spectrometry to perform micro-scale mapping, allowing the measurement of diffusion coefficients for a mixture of chemical tracers for tuff cubes and tetrahedrons having two contact geometries (cube-cube and cube-tetrahedron). The x-ray computed tomography images show limited contact between grains, and …

Evaluation of solute diffusion in unsaturated porous gravel is very important for investigations of contaminant transport and remediation, risk assessment, and waste disposal (for example, the potential high-level nuclear waste repository at Yucca Mountain, Nevada). For a porous aggregate medium such as granular tuff, the total water content is comprised of surface water and interior water. The surface water component (water film around grains and pendular water between the grain contacts) could serve as a predominant diffusion pathway. To investigate the extent to which surface water films and contact points affect solute diffusion in unsaturated gravel, we examined the configuration of water using x-ray computed tomography in partially saturated gravel, and made quantitative measurements of diffusion at multiple water contents using two different techniques. In the first, diffusion coefficients of potassium chloride in 2-4 mm granular tuff at multiple water contents were calculated from electrical conductivity measurements using the Nernst-Einstein equation. In the second, we used laser ablation with inductively coupled plasma-mass spectrometry to perform micro-scale mapping, allowing the measurement of diffusion coefficients for a mixture of chemical tracers for tuff cubes and tetrahedrons having two contact geometries (cube-cube and cube-tetrahedron). The x-ray computed tomography images show limited contact between …

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The objective of this project is to develop a portable analytical system based on the on-line/on-chip coupling of a miniaturized sample processing system with a microfabricated capillary electrophoresis/electrochemical detector for fast separation/detection of explosives and their degradation products in groundwater. Such a system has the potential to provide reliable, cost-effective characterization of groundwater contamination at DoD sites that are undergoing closure and remediation. A capillary electrophoresis (CE) microdevice, based on the combination of microfabricated separation chips and thick-film electrochemical detector strips, was developed. The microdevice consists of a planar screen-printed carbon line electrode mounted perpendicular to the now direction. Such coupling obviates the need for permanent attachment of the detector, to allow easy and fast replacement of the working electrode. Variables influencing the separation efficiency and amperometric response, including the channel-electrode spacing, separation voltage, or detection potential, are assessed and optimized. The versatility, simplicity, and low-cost advantages of the design are coupled to an attractive performance, with submicromolar detection limits, and good precision. Applicability for assays of mixtures of nitroaromatic explosives has been demonstrated. On-line coupling of preconcentration/microchip separation for explosives will also be presented.

Ophir Corporation was awarded a contract by the U. S. Department of Energy, National Energy Technology Laboratory under the Project Title ''Airborne, Optical Remote Sensing of Methane and Ethane for Natural Gas Pipeline Leak Detection'' on October 14, 2002. This second six-month technical report summarizes the progress made towards defining, designing, and developing the hardware and software segments of the airborne, optical remote methane and ethane sensor. The most challenging task to date has been to identify a vendor capable of designing and developing a light source with the appropriate output wavelength and power. This report will document the work that has been done to identify design requirements, and potential vendors for the light source. Significant progress has also been made in characterizing the amount of light return available from a remote target at various distances from the light source. A great deal of time has been spent conducting laboratory and long-optical path target reflectance measurements. This is important since it helps to establish the overall optical output requirements for the sensor. It also reduces the relative uncertainty and risk associated with developing a custom light source. The data gathered from the optical path testing has been translated to the …

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Structural phase transitions in the rare-earth metal Dysprosium have been studied in a Diamond Anvil Cell (DAC) to 119 GPa by x-ray diffraction. Four transformations following the sequence hcp {yields} Sm-type {yields} dhcp {yields} hR24 (hexagonal) {yields} bcm (monoclinic) are observed at 6, 15, 43, and 73 GPa respectively. The hexagonal to monoclinic transformation is accompanied by a 6% reduction in volume, which is attributed to delocalization of the 4f electrons, similar to that seen in Ce, Pr, and Gd.

The purpose of this research project is to develop compact (100 to 400 MWe) Generation IV nuclear power plant design and layout concepts that maximize the benefits of factory-based fabrication and optimal packaging, transportation and siting. The reactor concepts selected were compact designs under development in the 2000 to 2001 period. This interdisciplinary project was comprised of three university-led nuclear engineering teams identified by reactor coolant type (water, gas, and liquid metal) and a fourth Industrial Engineering team. The reactors included a Modular Pebble Bed helium-cooled concept being developed at MIT, the IRIS water-cooled concept being developed by a team led by Westinghouse Electric Company, and a Lead-Bismuth-cooled concept developed by UT. In addition to the design and layout concepts this report includes a section on heat exchanger manufacturing simulations and a section on construction and cost impacts of proposed modular designs.