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High-precision reflectometry of multilayer coatings for extreme ultraviolet lithography (open access)

High-precision reflectometry of multilayer coatings for extreme ultraviolet lithography

Synchrotron-based reflectometry is an important technique for the precise determination of optical properties of reflective multilayer coatings for Extreme Ultraviolet Lithography (EUVL). Multilayer coatings enable normal incidence reflectances of more than 65% in the wavelength range between 11 and 15 nm. In order to achieve high resolution and throughput of EUVL systems, stringent requirements not only apply to their mechanical and optical layout, but also apply to the optical properties of the multilayer coatings. Therefore, multilayer deposition on near-normal incidence optical surfaces of projection optics, condenser optics and reflective masks requires suitable high-precision metrology. Most important, due to their small bandpass on the order of only 0.5 nm, all reflective multilayer coatings in EUVL systems must be wavelength-matched to within {+-}0.05 nm. In some cases, a gradient of the coating thickness is necessary for wavelength matching at variable average angle of incidence in different locations on the optical surfaces. Furthermore, in order to preserve the geometrical figure of the optical substrates, reflective multilayer coatings need to be uniform to within 0.01 nm in their center wavelength. This requirement can only be fulfilled with suitable metrology, which provides a precision of a fraction of this value. In addition, for the detailed …
Date: December 29, 1999
Creator: Wedowski, M; Underwood, J H; Gullikson, E M; Bajt, S; Folta, J A; Kearney, P A et al.
System: The UNT Digital Library
Spherical Harmonic Solutions to the 3D Kobayashi Benchmark Suite (open access)

Spherical Harmonic Solutions to the 3D Kobayashi Benchmark Suite

Spherical harmonic solutions of order 5, 9 and 21 on spatial grids containing up to 3.3 million cells are presented for the Kobayashi benchmark suite. This suite of three problems with simple geometry of pure absorber with large void region was proposed by Professor Kobayashi at an OECD/NEA meeting in 1996. Each of the three problems contains a source, a void and a shield region. Problem 1 can best be described as a box in a box problem, where a source region is surrounded by a square void region which itself is embedded in a square shield region. Problems 2 and 3 represent a shield with a void duct. Problem 2 having a straight and problem 3 a dog leg shaped duct. A pure absorber and a 50% scattering case are considered for each of the three problems. The solutions have been obtained with Ardra, a scalable, parallel neutron transport code developed at Lawrence Livermore National Laboratory (LLNL). The Ardra code takes advantage of a two-level parallelization strategy, which combines message passing between processing nodes and thread based parallelism amongst processors on each node. All calculations were performed on the IBM ASCI Blue-Pacific computer at LLNL.
Date: December 29, 1999
Creator: Brown, P.N.; Chang, B. & Hanebutte, U.R.
System: The UNT Digital Library
Effect of Flux Adjustments on Temperature Variability in Climate Models (open access)

Effect of Flux Adjustments on Temperature Variability in Climate Models

It has been suggested that ''flux adjustments'' in climate models suppress simulated temperature variability. If true, this might invalidate the conclusion that at least some of observed temperature increases since 1860 are anthropogenic, since this conclusion is based in part on estimates of natural temperature variability derived from flux-adjusted models. We assess variability of surface air temperatures in 17 simulations of internal temperature variability submitted to the Coupled Model Intercomparison Project. By comparing variability in flux-adjusted vs. non-flux adjusted simulations, we find no evidence that flux adjustments suppress temperature variability in climate models; other, largely unknown, factors are much more important in determining simulated temperature variability. Therefore the conclusion that at least some of observed temperature increases are anthropogenic cannot be questioned on the grounds that it is based in part on results of flux-adjusted models. Also, reducing or eliminating flux adjustments would probably do little to improve simulations of temperature variability.
Date: December 27, 1999
Creator: Duffy, P.; Bell, J.; Covey, C. & Sloan, L.
System: The UNT Digital Library
Development of metrological NDE methods for microturbine ceramic components (open access)

Development of metrological NDE methods for microturbine ceramic components

In this work, X-ray computed tomographic imaging technology with high spatial resolution has been explored for metrological applications to Si{sub 3}N{sub 4} ceramic turbine wheels. X-ray computed tomography (XCT) data were acquired by a charge-coupled device detector coupled to an image intensifier. Cone-beam XCT reconstruction algorithms were used to allow full-volume data acquisition from the turbine wheels. Special software was developed so that edge detection and complex blade contours could be determined from the XCT data. The feasibility of using the XCT for dimensional analyses was compared with that of a coordinate-measuring machine. Details of the XCT system, data acquisition, and dimensional comparisons will be presented.
Date: December 23, 1999
Creator: Lee, H.-R. & Ellingson, W. A.
System: The UNT Digital Library
The investigation of phase evolution in composite ceramic superconductors using Raman microscopy techniques (open access)

The investigation of phase evolution in composite ceramic superconductors using Raman microscopy techniques

Raman microspectroscopy and imaging techniques have been used to investigate key mechanistic features that influence the formation of layered Bi- and Tl-based superconducting phases during the thermal treatment employed to produce BSCCO and TBCCO composite conductors. Seminal information gained from these studies includes the location of lead-rich nonsuperconducting second phases (NSPS) and the identification of the constituent phases in certain NSP agglomerations that tend to resist dissipation as high-Tc phase formation proceeds to completion.
Date: December 23, 1999
Creator: Maroni, V. A.; Fischer, A. K. & Wu, K. T.
System: The UNT Digital Library
Laser conditioning methods of Hafnia Silica multilayer mirrors (open access)

Laser conditioning methods of Hafnia Silica multilayer mirrors

None
Date: December 23, 1999
Creator: Hue, J; Maricle, S M; Schwartz, S; Sheehan, L M & Stolz, C J
System: The UNT Digital Library
Phase stability domains of (Bi,Pb-2223): Data sources, correlation, and assessment (open access)

Phase stability domains of (Bi,Pb-2223): Data sources, correlation, and assessment

An assessment of the phase stability of lead-doped Bi-2223, (Bi,Pb)-2223, as a function of temperature and partial pressure of oxygen, p(0{sub 2}), derived from equilibration and electromotive force studies carried out by numerous groups of investigators is presented. The data obtained from this assessment, coupled with additional more recent data from the laboratory, can be used to estimate the stability of this promising high-{Tc} bismuth cuprate system in the temperature range from 650 to 870 C and for oxygen partial pressures ranging from 10{sup {minus}5} to one atm.
Date: December 23, 1999
Creator: Tetenbaum, M.; Maroni, V. A.; Murphy, N. M. & Dorris, S. E.
System: The UNT Digital Library
Role of starting material composition in interfacial damage morphology of Hafnia Silica multilayer coatings (open access)

Role of starting material composition in interfacial damage morphology of Hafnia Silica multilayer coatings

None
Date: December 23, 1999
Creator: Bevis, R P; Stolz, C J; Von Gunten, M K; Weakley, S C & Wu, Z L
System: The UNT Digital Library
Scenario analysis of hybrid class 3-7 heavy vehicles. (open access)

Scenario analysis of hybrid class 3-7 heavy vehicles.

The effects of hybridization on heavy-duty vehicles are not well understood. Heavy vehicles represent a broader range of applications than light-duty vehicles, resulting in a wide variety of chassis and engine combinations, as well as diverse driving conditions. Thus, the strategies, incremental costs, and energy/emission benefits associated with hybridizing heavy vehicles could differ significantly from those for passenger cars. Using a modal energy and emissions model, they quantify the potential energy savings of hybridizing commercial Class 3-7 heavy vehicles, analyze hybrid configuration scenarios, and estimate the associated investment cost and payback time. From the analysis, they conclude that (1) hybridization can significantly reduce energy consumption of Class 3-7 heavy vehicles under urban driving conditions; (2) the grid-independent, conventional vehicle (CV)-like hybrid is more cost-effective than the grid-dependent, electric vehicle (EV)-like hybrid, and the parallel configuration is more cost-effective than the series configuration; (3) for CV-like hybridization, the on-board engine can be significantly downsized, with a gasoline or diesel engine used for SUVs perhaps being a good candidate for an on-board engine; (4) over the long term, the incremental cost of a CV-like, parallel-configured Class 3-4 hybrid heavy vehicle is about %5,800 in the year 2005 and $3,000 in 2020, while …
Date: December 23, 1999
Creator: An, F.; Stodolsky, F.; Vyas, A.; Cuenca, R. & Eberhardt, J. J.
System: The UNT Digital Library
Through the looking glass: Unraveling the network structure of coal (open access)

Through the looking glass: Unraveling the network structure of coal

Since the original idea by Sanada and Honda of treating coal as a three-dimensional cross-linked network, coal structure has been probed by monitoring ingress of solvents using traditional volumetric or gravimetric methods. However, using these techniques has allowed only an indirect observation of the swelling process. More recently, the authors have developed magnetic resonance microscopy (MRM) approaches for studying solvent ingress in polymeric systems, about which fundamental aspects of the swelling process can be deduced directly and quantitatively. The aim of their work is to utilize solvent transport and network response parameters obtained from these methods to assess fundamental properties of the system under investigation. Polymer and coal samples have been studied to date. Numerous swelling parameters measured by magnetic resonance microscopy are found to correlate with cross-link density of the polymer network under investigation. Use of these parameters to assess the three-dimensional network structure of coal is discussed.
Date: December 23, 1999
Creator: Gregory, D. M.; Stec, D. F. & Botto, R. E.
System: The UNT Digital Library
Analysis of Parameters Affecting Beam Gauge Performance (open access)

Analysis of Parameters Affecting Beam Gauge Performance

Beam gauges have been used in the last decade or so for measuring the internal azimuthal compressive coil stresses in superconducting magnets. In early model Large Hadron Collider Interaction Region (LHC IR) quadrupoles tested at Fermilab, the beam gauges indicated excessively high amounts of inner and outer coil prestress during the collaring process, inconsistent with the coil size and modulus data. In response to these measurements, a simple mechanics based quantitative understanding of different factors affecting beam gauges has been developed. A finite element model with contact elements and non-linear material behavior, confirmed with experimental results, was developed. The results indicate that a small plastic deformation of either the beam or the backing plate can cause significant errors in the measured stress values. The effect of variations in coil modulus and support boundary conditions on beam gauge performance are also discussed.
Date: December 22, 1999
Creator: S. Yadav, J. Kerby and J.P. Ozelis
System: The UNT Digital Library
(Ba,Sr)TiO{sub 3} dielectrics: Relationship between bulk and thin film properties (open access)

(Ba,Sr)TiO{sub 3} dielectrics: Relationship between bulk and thin film properties

Thin films of complex perovskites have a number of potentially important applications. Of major scientific and practical concern is the scaling of properties as film dimensions are reduced. This paper describes a satisfactory relationship between bulk and thin film dielectric properties of (Ba,Sr)TiO{sub 3}. Relative contributions of strain, A:B cation stoichiometry, and interface are separated to explain temperature dependent dielectric behavior.
Date: December 22, 1999
Creator: Kingon, A. I.; Streiffer, S. K.; Parker, C. B. & Stemmer, S.
System: The UNT Digital Library
Correlating radiation exposure with embrittlement: Comparative studies of electron- and neutron-irradiated pressure vessel alloys (open access)

Correlating radiation exposure with embrittlement: Comparative studies of electron- and neutron-irradiated pressure vessel alloys

Comparative experiments using high energy (10 MeV) electrons and test reactor neutrons have been undertaken to understand the role that primary damage state has on hardening (embrittlement) induced by irradiation at 300 C. Electrons produce displacement damage primarily by low energy atomic recoils, while fast neutrons produce displacements from considerably higher energy recoils. Comparison of changes resulting from neutron irradiation, in which nascent point defect clusters can form in dense cascades, with electron irradiation, where cascade formation is minimized, can provide insight into the role that the in-cascade point defect clusters have on the mechanisms of embrittlement. Tensile property changes induced by 10 MeV electrons or test reactor neutron irradiations of unalloyed iron and an Fe-O.9 wt.% Cu-1.0 wt.% Mn alloy were examined in the damage range of 9.0 x 10{sup {minus}5} dpa to 1.5 x 10{sup {minus}2} dpa. The results show the ternary alloy experienced substantially greater embrittlement in both the electron and neutron irradiate samples relative to unalloyed iron. Despite their disparate nature of defect production similar embrittlement trends with increasing radiation damage were observed for electrons and neutrons in both the ternary and unalloyed iron.
Date: December 22, 1999
Creator: Alexander, D. E.; Rehn, L. E.; Odette, G. R.; Lucas, G. E.; Klingensmith, D. & Gragg, D.
System: The UNT Digital Library
Electron channeling X-ray microanalysis for cation configuration in irradiate magnesium aluminate spinel (open access)

Electron channeling X-ray microanalysis for cation configuration in irradiate magnesium aluminate spinel

High angular resolution electron channeling X-ray spectroscopy (HARECXS) was examined as a practical tool to locate lattice-ions in spinel crystals. The orientation dependent intensity distribution of emitted X-rays obtained by HARECXS is so sensitive to lattice-ion configuration in the illuminated areas that the occupation probabilities on specific positions in the crystal lattice can be determined accurately through comparison with the theoretical rocking curves. HARECXS measurements have revealed partially disordered cation arrangement in MgO{center_dot}nAl{sub 2}O{sub 3} with n = 1.0 and 2.4. Most Al{sup 3+} lattice-ions occupy the octahedral (VIII) sites, while Mg{sup 2} lattice-ions reside on both the tetrahedral (IV) and the octahedral (VIII) sites. The structural vacancies are enriched in the IV-sites. Further evacuation of cations from the IV-sites to the VIII-sites is recognized in a disordering process induced by irradiation with 1 MeV Ne{sup +} ions up to 8.9 dpa at 870 K.
Date: December 22, 1999
Creator: Matsumura, S.; Soeda, T.; Zaluzec, N. J. & Kinoshita, C.
System: The UNT Digital Library
Evaluation of plasma-sprayed CoS{sub 2} cathodes for thermal batteries (open access)

Evaluation of plasma-sprayed CoS{sub 2} cathodes for thermal batteries

Conventional electroactive stack components in thermal batteries are constructed from pressed-powder parts. These include the anode, separator, and cathode pellets (discs). Pressing parts that are less than 0.010 inch thick is difficult. The use of plasma spray to deposit thin CoS{sub 2} cathode films onto a stainless steel substrate was examined as an alternative to pressed-powder cathodes. The plasma-sprayed electrodes were tested in single cells under isothermal conditions and constant-current discharge over a temperature range of 400 C to 550 C using standard LiSi anodes and separators based on the LiCl-KCl eutectic. Similar tests were conducted with cells built with conventional pressed-powder cathodes, which were tested under the same conditions for comparative purposes. This paper presents the results of those tests.
Date: December 22, 1999
Creator: Guidotti, R.A.
System: The UNT Digital Library
Higgs Mass Determination From Direct Reconstruction at a Linear E+E- Collider (open access)

Higgs Mass Determination From Direct Reconstruction at a Linear E+E- Collider

We study the feasibility of a precise measurement of the mass of a 120 GeV MSM Higgs boson through direct reconstruction of ZH {yields} q{bar q}H events that would be achieved in a future e{sup +}e{sup -} linear collider operating at a center-of-mass energy of 500 GeV. Much effort has been put in a ''realistic simulation'' by including irreducible+reducible backgrounds, realistic detector effects and reconstruction procedures and sophisticated analysis tools involving Neural Networks and kinematical fitting. As a result, the Higgs mass is determined with a statistical accuracy of 50 MeV and the Z-Higgs Yukawa coupling measured to 0.7%, assuming 500 fb{sup -1} of integrated luminosity.
Date: December 22, 1999
Creator: Juste, A.
System: The UNT Digital Library
Laser modulated scattering as a nondestructive evaluation tool for optical surfaces and thin film coatings (open access)

Laser modulated scattering as a nondestructive evaluation tool for optical surfaces and thin film coatings

Laser modulated scattering (LMS) is introduced as a non-destructive evaluation tool for defect inspection and characterization of optical surfaces and thin film coatings. This technique is a scatter sensitive version of the well-known photothermal microscopy (PTM) technique. It allows simultaneous measurement of the DC and AC scattering signals of a probe laser beam from an optical surface. By comparison between the DC and AC scattering signals, one can differentiate absorptive defects from non-absorptive ones. This paper describes the principle of the LMS technique and the experimental setup, and illustrates examples on using LMS as a tool for nondestructive evaluation of high quality optics.
Date: December 22, 1999
Creator: Feit, M D; Kozlowski, M R; Rubenchik, A M; Sheehan, L & Wu, Z L
System: The UNT Digital Library
Mechanistic study of dielectric chemical mechanical polishing by spectral and scaling analysis of atomic force microscope images (open access)

Mechanistic study of dielectric chemical mechanical polishing by spectral and scaling analysis of atomic force microscope images

Thermal oxide and PETEOS oxide surfaces, polished on an IPEC 472 with different combinations of polish pad, slurry, and polishing conditions, were studied with ex situ atomic force microscopy. The post polish surfaces were analyzed qualitatively by visual inspection and quantitatively by spectral and scaling analyses. Spectral and scaling analyses gave consistent interpretations of morphology evolution. Polishing with either a fixed abrasive pad or alumina-based slurry occurred via a mechanism for which asperities are removed and recesses are filled. A sputtering-type mechanism may contribute to material removal when polishing with silica- or ceria-based slurries.
Date: December 22, 1999
Creator: Verhoff, M.L.
System: The UNT Digital Library
Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-PbTiO{sub 3} thin films synthesized by metalorganic chemical vapor deposition (open access)

Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-PbTiO{sub 3} thin films synthesized by metalorganic chemical vapor deposition

Metalorganic chemical vapor deposition was used to synthesize epitaxial Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}{minus}PbTiO{sub 3} films on SrTiO{sub 3} and SrRuO{sub 3}/SrTiO{sub 3} substrates, using solid Mg(DPM){sub 2} as the Mg precursor. Depositing conditions have been identified under which phase-pure perovskite PMN-PT may be grown. In contrast, in lead-poor environments, an additional second phases of a disordered magnesium-niobium oxide has tentatively been identified. X-ray diffraction and selected area electron diffraction indicate a cube-on-cube orientation relationship between film and substrate, with a (001) rocking curve width of 0.1{degree}, and in-plane mosaic of 0.8{degree}. The rms surface roughness of a 200nm thick PMN film on SrTiO{sub 3} was 2 to 3 nm as measured by scanned probe microscopy. The zero-bias dielectric constant and loss measured at room temperature and 10 kHz for a 350 nm thick pure PMN film on SrRuO{sub 3}/SrTiO{sub 3} were 1100 and 2%, respectively. Small-signal permittivity ranged from 900 to 1400 depending on deposition conditions and Ti content; low values for the dielectric loss between 1 and 3% were determined for all specimens. Here the authors report on growth conditions and the initial structural and dielectric characterization of these samples.
Date: December 22, 1999
Creator: Streiffer, S. K.; Bai, G. R.; Auciello, O.; Baumann, P. K.; Ghosh, K.; Munkholm, A. et al.
System: The UNT Digital Library
Rare B decays, mixing and cp violation at the Fermilab Tevatron (open access)

Rare B decays, mixing and cp violation at the Fermilab Tevatron

Over two decades since its discovery at Fermilab in 1977, the b quark has become an important laboratory for the exploration of the Standard Model as well as a potential window beyond it. Its kinematic properties, its large mass and long lifetime, and its large production cross section in hadron collisions, make it an excellent subject of study at the Tevatron {bar p}p collider. In this article, we will review recent results from CDF and D0 in two categories of tests of the Standard Model: the search for rare b decays, and the measurement of asymmetry parameters related to B{sup 0} meson mixing and CP violation. The detectors have been described elsewhere. The data for the results presented here are from the 1992-96 collider run, representing at each experiment, approximately 100 pb{sup -1} of integrated luminosity at {radical}s = 1.8 TeV.
Date: December 22, 1999
Creator: Tseng, J.
System: The UNT Digital Library
Recent Results from CDF (open access)

Recent Results from CDF

We present the latest results from the CDF experiment at the Tevatron Collider in p{bar p} collisions at {radical}s = 1.8 TeV. The large data sample collected during Run 1, from 1992 until 1995, allows measurements in many domains of high-energy physics. Here, we report on the first measurement of sin(2{beta}), a CP violation parameter, and on an improved measurement of the top quark cross section. We also report on searches for the so-far elusive Higgs boson, and for SUSY, through searches for direct production of top and bottom scalar quarks. Finally, we outline the prospects for the physics during the upcoming Run 2, ready to start in the upcoming year 2000.
Date: December 22, 1999
Creator: Gallinaro, Michele
System: The UNT Digital Library
Temperature dependence of ion irradiation induced amorphization of zirconolite (open access)

Temperature dependence of ion irradiation induced amorphization of zirconolite

Zirconolite is one of the major host phases for actinides in various wasteforms for immobilizing high level radioactive waste (HLW). Over time, zirconolite's crystalline matrix is damaged by {alpha}-particles and energetic recoil nuclei recoil resulting from {alpha}-decay events. The cumulative damage caused by these particles results in amorphization. Data from natural zirconolites suggest that radiation damage anneals over geologic time and is dependant on the thermal history of the material. Proposed HLW containment strategies rely on both a suitable wasteform and geologic isolation. Depending on the waste loading, depth of burial, and the repository-specific geothermal gradient, burial could result in a wasteform being exposed to temperatures of between 100--450 C. Consequently, it is important to assess the effect of temperature on radiation damage in synthetic zirconolite. Zirconolite containing wasteforms are likely to be hot pressed at or below 1,473 K (1,200 C) and/or sintered at or below 1,623 K (1,350 C). Zirconolite fabricated at temperatures below 1,523 K (1,250 C) contains many stacking faults. As there have been various attempts to link radiation resistance to structure, the authors decided it was also pertinent to assess the role of stacking faults in radiation resistance. In this study, they simulate {alpha}-decay damage …
Date: December 22, 1999
Creator: Smith, K. L.; Blackford, M. G.; Lumpkin, G. R. & Zaluzec, N. J.
System: The UNT Digital Library
Trilinear gauge boson couplings and vector boson pair production (open access)

Trilinear gauge boson couplings and vector boson pair production

The trilinear couplings appear as the three gauge boson vertices and can be measured by studying the gauge boson pair production processes. The measurement of the coupling parameters is one of the few remaining crucial tests of the Standard Model. D0 has studied W{gamma}, Z{gamma}, WW, and WZ production and found no evidence of anomalous production. In this paper we review all the current results from D0 data.
Date: December 22, 1999
Creator: Sanchez-Hernandez, A.
System: The UNT Digital Library
Ba{sub 1{minus}x}Sr{sub x}TiO{sub 3} thin film sputter-growth processes and electrical property relationships for high frequency devices (open access)

Ba{sub 1{minus}x}Sr{sub x}TiO{sub 3} thin film sputter-growth processes and electrical property relationships for high frequency devices

Precise control of Ba{sub 1{minus}x}Sr{sub x}Ti0{sub 3} (BST) film composition is critical for the production of high-quality BST thin films. Specifically, it is known that nonstoichiometry greatly affects the electrical properties of BST film capacitors. The authors are investigating the composition-microstructure-electrical property relationships of polycrystalline BST films produced by magnetron sputter-deposition using a single target with a Ba/Sr ratio of 50/50 and a (Ba+Sr)/Ti ratio of 1.0. It was determined that the (Ba+Sr)/Ti ratios of these BST films could be adjusted from 0.73 to 0.98 by changing the total (Ar+O{sub 2}) process pressure, while the O{sub 2}/Ar ratio did not strongly affect the metal ion composition. The crystalline quality as well as the measured dielectric constant, dielectric tunability, and electrical breakdown voltage of BST films have been found to be strongly dependent on the composition of the BST films, especially the (Ba+Sr)/Ti ratio. The authors discuss the impact of BST film composition control, through film deposition and process parameters, on the electrical properties of BST capacitors for high frequency devices.
Date: December 21, 1999
Creator: Im, J.; Auciello, O.; Streiffer, S. K.; Baumann, P. K.; Eastman, J. A.; Kaufman, D. Y. et al.
System: The UNT Digital Library