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.
Object Type: Article
System: The UNT Digital Library
A Novel Approach to Material Development for Advanced Reactor Systems (open access)

A Novel Approach to Material Development for Advanced Reactor Systems

OAK B188 A Novel Approach to Material Development for Advanced Reactor Systems. Year one of this project had three major goals. First, to specify, order and install a new high current ion source for more rapid and stable proton irradiation. Second, to assess the use low temperature irradiation and chromium pre-enrichment in an effort to isolate a radiation damage microstructure in stainless steels without the effects of RIS. Third, to prepare for the irradiation of reactor pressure vessel steel and Zircaloy. In year 1 quarter 1, the project goal was to order the high current ion source and to procure and prepare samples of stainless steel for low temperature proton irradiation.
Date: December 22, 1999
Creator: Was, G.S.; Atzmon, M. & Wang, L.
Object Type: Report
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.
Object Type: Article
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.
Object Type: Article
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
Object Type: Article
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.
Object Type: Article
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.
Object Type: Article
System: The UNT Digital Library
Analysis of Hazardous Biological Materials by MALDI Mass Spectrometry (open access)

Analysis of Hazardous Biological Materials by MALDI Mass Spectrometry

Analysis of Hazardous Biological Materials by MALDI Mass Spectrometry
Date: December 21, 1999
Creator: Wahl, Karen L.; Jarman, Kristin H.; Valentine, Nancy B.; Kingsley, Mark T.; Petersen, Catherine E.; Wunschel, Sharon C. et al.
Object Type: Report
System: The UNT Digital Library
AQUEOUS BIPHASE EXTRACTION FOR PROCESSING OF FINE COAL (open access)

AQUEOUS BIPHASE EXTRACTION FOR PROCESSING OF FINE COAL

None
Date: December 21, 1999
Creator: Osseo-Asare, K.
Object Type: Report
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.
Object Type: Article
System: The UNT Digital Library
Calderon cokemaking process/demonstration project (open access)

Calderon cokemaking process/demonstration project

This project deals with the demonstration of a coking process using proprietary technology of Calderon, with the following objectives geared to facilitate commercialization: (1) making coke of such quality as to be suitable for use in hard-driving, large blast furnaces; (2) providing proof that such a process is continuous and environmentally closed to prevent emissions; (3) demonstrating that high-coking-pressure (non-traditional) coal blends which cannot be safely charged into conventional by-product coke ovens can be used in the Calderon process; (4) conducting a blast furnace test to demonstrate the compatibility of the coke produced; and (5) demonstrating that coke can be produced economically, at a level competitive with coke imports. The activities of the past quarter continued to be focused on the following: Drafting of Contracts among the Stakeholders of the Team, Completion and Delivery of Proposal for Phase 2 Permitting and Environmental Work Engineering Progress Preparation of Final Report for Phase 1 DCAA Audit Funding for Phase 2.
Date: December 21, 1999
Creator: Calderon, Albert
Object Type: Report
System: The UNT Digital Library
Collectivity of the ''Three-Phonon'' Region in {sup 100}Ru (open access)

Collectivity of the ''Three-Phonon'' Region in {sup 100}Ru

We have studied the quadrupole degree of freedom in a typical vibrational nucleus, {sup 100}Ru. From inelastic neutron scattering at the Van de Graaff accelerator of the University of Kentucky, lifetimes of states in {sup 100}Ru were determined. Absolute transition rates or limits thereon were extracted and compared to the theoretical description of this nucleus.
Date: December 21, 1999
Creator: Genilloud, L.; Brown, T.B.; Corminboeuf, G & Garrett, P.
Object Type: Article
System: The UNT Digital Library
Commercial Grade Item (CGI) Dedication for Leak Detection Relays (open access)

Commercial Grade Item (CGI) Dedication for Leak Detection Relays

This Test Plan provides a test method to dedicate the leak detection relays used on the new Pumping and Instrumentation Control (PIC) skids. The new skids are fabricated on-site. The leak detection system is a safety class system per the Authorization Basis.
Date: December 21, 1999
Creator: Koch, M. R. & Johns, B. R.
Object Type: Report
System: The UNT Digital Library
Device physics of thin-film polycrystalline cells and modules: Phase 1 annual report: February 1998--January 1999 (open access)

Device physics of thin-film polycrystalline cells and modules: Phase 1 annual report: February 1998--January 1999

This report describes work done by Colorado State University (CSU) during Phase 1 of this subcontract. CSU researchers continued to make basic measurements on CI(G)S and CdTe solar cells fabricated at different labs, to quantitatively deduce the loss mechanisms in these cells, and to make appropriate comparisons that illuminate where progress is being made. Cells evaluated included the new record CIGS cell, CIS cells made with and without CdS, and those made by electrodeposition and electroless growth from solution. Work on the role of impurities focused on sodium in CIS. Cells with varying amounts of sodium added during CIS deposition were fabricated at NREL using four types of substrates. The best performance was achieved with 10{sup {minus}2}--10{sup {minus}1} at% sodium, and the relative merits of proposed mechanisms for the sodium effect were compared. Researchers also worked on the construction and testing of a fine-focused laser-beam apparatus to measure local variations in polycrystalline cell performance. A 1{micro}m spot was achieved, spatial reproducibility in one and two dimensions is less than 1 {micro}m, and photocurrent is reliably measured when the 1{micro}m spot is reduced as low as 1-sun in intensity. In elevated-temperature stress tests, typical CdTe cells held at 100 C under …
Date: December 21, 1999
Creator: Sites, J. R.
Object Type: Report
System: The UNT Digital Library
Disorder-driven nonequilibrium melting studied by electron diffraction, brillouis scattering, and molecular dynamics (open access)

Disorder-driven nonequilibrium melting studied by electron diffraction, brillouis scattering, and molecular dynamics

In the present paper, a brief overview of the electron diffraction, Brillouin scattering and molecular dynamics studies of radiation-induced amorphization of ordered intermetallic compounds is presented. In these studies, measured changes in the velocity of surface acoustic phonons, lattice constant, and the Bragg-Williams long-range order parameter induced by irradiation were compared with the results of computer simulations of defect-induced amorphization. The results indicate that progressive chemical disordering of the superlattice structure during irradiation is accompanied by an expansion of the lattice and a large change in sound velocity corresponding to a {approximately} 50% decrease in the average shear modulus. The onset of amorphization occurs when the average shear modulus of the crystalline compound becomes equal to that of the amorphous phase. This elastic softening criterion for the onset of amorphization and the dependence of the average shear modulus on the long-range-order parameter are in excellent agreement with molecular dynamics simulations. Both the experimental observations and computer simulations confirm the predictions of the generalized Lindemann melting criterion which stipulates that thermodynamic melting of a defective crystal occurs when the sum of the dynamic and static mean-square atomic displacements reaches a critical value identical to that for melting of the defect-free crystal. …
Date: December 21, 1999
Creator: Okamoto, P. R.; Lam, N. Q. & Grimsditch, M.
Object Type: Article
System: The UNT Digital Library
Distributed System Intruder Tools, Trinoo and Tribe Flood Network (open access)

Distributed System Intruder Tools, Trinoo and Tribe Flood Network

Trinoo and Tribe Flood Network (TFN) are new forms of denial of Service (DOS) attacks. attacks are designed to bring down a computer or network by overloading it with a large amount of network traffic using TCP, UDP, or ICMP. In the past, these attacks came from a single location and were easy to detect. Trinoo and TFN are distributed system intruder tools. These tools launch DoS attacks from multiple computer systems at a target system simultaneously. This makes the assault hard to detect and almost impossible to track to the original attacker. Because these attacks can be launched from hundreds of computers under the command of a single attacker, they are far more dangerous than any DoS attack launched from a single location. These distributed tools have only been seen on Solaris and Linux machines, but there is no reason why they could not be modified for UNIX machines. The target system can also be of any type because the attack is based on the TCP/IP architecture, not a flaw in any particular operating system (OS). CIAC considers the risks presented by these DoS tools to be high.
Date: December 21, 1999
Creator: Criscuolo, P.J. & Rathbun, T
Object Type: Report
System: The UNT Digital Library
Geologic Data Package for 2001 Immobilized Low-Activity Waste Performance Assessment (open access)

Geologic Data Package for 2001 Immobilized Low-Activity Waste Performance Assessment

This database is a compilation of existing geologic data from both the existing and new immobilized low-activity waste disposal sites for use in the 2001 Performance Assessment. Data were compiled from both surface and subsurface geologic sources. Large-scale surface geologic maps, previously published, cover the entire 200-East Area and the disposal sites. Subsurface information consists of drilling and geophysical logs from nearby boreholes and stored sediment samples. Numerous published geological reports are available that describe the subsurface geology of the area. Site-specific subsurface data are summarized in tables and profiles in this document. Uncertainty in data is mainly restricted to borehole information. Variations in sampling and drilling techniques present some correlation uncertainties across the sites. A greater degree of uncertainty exists on the new site because of restricted borehole coverage. There is some uncertainty to the location and orientation of elastic dikes across the sites.
Date: December 21, 1999
Creator: Reidel, S. P. & Horton, D. G.
Object Type: Report
System: The UNT Digital Library
Geotechnical Issues in Total System Performance Assessments of Yucca Mountain (open access)

Geotechnical Issues in Total System Performance Assessments of Yucca Mountain

A Total System Performance Assessment (TSPA) of Yucca Mountain consists of integrated sub-models and analyses of natural and engineered systems. Examples of subsystem models include unsaturated-zone flow and transport, seepage into drifts, coupled thermal hydrologic processes, transport through the engineered barrier system, and saturated-zone flow and transport. The TSPA evaluates the interaction of important processes among these subsystems, and it determines the impact of these processes on the overall performance measures (e.g., dose rate to humans). This paper summarizes the evaluation, abstraction, and combination of these subsystem models in a TSPA calculation, and it provides background on the individual TSPA subsystem components that are most directly impacted by geotechnical issues. The potential impact that geologic features, events, and processes have on the overall performance is presented, and an evaluation of the sensitivity of TSPA calculations to these issues is also provided.
Date: December 21, 1999
Creator: HO,CLIFFORD K.; HOUSEWORTH,JIM & WILSON,MICHAEL L.
Object Type: Article
System: The UNT Digital Library
Independent Evaluation of Air Filter Media from Chornobyl (open access)

Independent Evaluation of Air Filter Media from Chornobyl

An independent evaluation was performed to assess the morphology, pressure drop characteristics, alpha spectroscopy characteristics, and collection efficiency of an air sampling filter media and two types of aerosol face masks provided from Chernobyl by Pacific Northwest National Laboratory. The evaluation included characterizing the filter morphology by scqg electron microscopy; measuring the filter pressure drop as a function of air flowrate; evaluating the spectroscopy characteristics of the filter for alpha-emitting radionuclides by sampling ambient radon progeny aerosols in an Eberline Alpha-6A alpha continuous air monitor; determining the particle collection efficiency of the filter media for 0.3 {micro}m aerodynamic diameter monodisperse particles at 1 and 2 cfm; and comparing the apparent construction, durability, and performance similarities of the filter media to other media commonly used for monitoring airborne alpha-emitting radionuclides.
Date: December 21, 1999
Creator: Hoover, MD; Fencl, AF & Vargo, GJ
Object Type: Report
System: The UNT Digital Library
Long-term operating experience for the ATLAS superconducting resonators (open access)

Long-term operating experience for the ATLAS superconducting resonators

Portions of the ATLAS accelerator have been operating now for over 21 years. The facility has accumulated several million resonator-hours of operation at this point and has demonstrated the long-term reliability of RF superconductivity. The overall operating performance of the ATLAS facility has established a level of beam quality, flexibility, and reliability not previously achieved with heavy-ion accelerator facilities. The actual operating experience and maintenance history of ATLAS are presented for ATLAS resonators and associated electronics systems. Solutions to problems that appeared in early operation as well as current problems needing further development are discussed.
Date: December 21, 1999
Creator: Pardo, R. & Zinkann, G.
Object Type: Article
System: The UNT Digital Library
Monte Carlo Simulations of Phosphate Polyhedron Connectivity in Glasses (open access)

Monte Carlo Simulations of Phosphate Polyhedron Connectivity in Glasses

Monte Carlo simulations of phosphate tetrahedron connectivity distributions in alkali and alkaline earth phosphate glasses are reported. By utilizing a discrete bond model, the distribution of next-nearest neighbor connectivities between phosphate polyhedron for random, alternating and clustering bonding scenarios was evaluated as a function of the relative bond energy difference. The simulated distributions are compared to experimentally observed connectivities reported for solid-state two-dimensional exchange and double-quantum NMR experiments of phosphate glasses. These Monte Carlo simulations demonstrate that the polyhedron connectivity is best described by a random distribution in lithium phosphate and calcium phosphate glasses.
Date: December 21, 1999
Creator: ALAM,TODD M.
Object Type: Article
System: The UNT Digital Library
Nanostructure of a-Si:H and related alloys by small-angle scattering of neutrons and X-rays: Annual technical progress report: May 22, 1998 -- May 21, 1999 (open access)

Nanostructure of a-Si:H and related alloys by small-angle scattering of neutrons and X-rays: Annual technical progress report: May 22, 1998 -- May 21, 1999

This report describes work being performed to provide details of the microstructure in high-quality hydrogenated amorphous silicon and related alloys on the nanometer scale. The materials under study are being prepared by state-of-the-art deposition methods, as well as by new and emerging deposition techniques. The purpose is to establish the role of nanostructural features in controlling opto-electronic and photovoltaic properties. The approach centers around the use of the uncommon technique of small-angle scattering of both X-rays (SAXS) and neutrons (SANS). SAXS has already been established as highly sensitive to microvoids and columnar-like microstructure. A major goal of this research is to establish the sensitivity of SANS to the hydrogen nanostructure. Conventional X-ray diffraction techniques are being used to examine medium-range order and microcrystallinity, particularly near the boundary between amorphous and microcrystalline material.
Date: December 21, 1999
Creator: Williamson, D. L.
Object Type: Report
System: The UNT Digital Library
Near-Field Hydrology Data Package for the Immobilized Low-Activity Waste 2001 Performance Assessment (open access)

Near-Field Hydrology Data Package for the Immobilized Low-Activity Waste 2001 Performance Assessment

Lockheed Martin Hanford Company (LMHC) is designing and assessing the performance of disposal facilities to receive radioactive wastes that are currently stored in single- and double-shell tanks at the Hanford Site. The preferred method for disposing of the portion that is classified as immobilized low-activity waste (ILAW) is to vitrify the waste and place the product in new-surface, shallow land burial facilities. The LMHC project to assess the performance of these disposal facilities is the Hanford ILAW Performance Assessment (PA) Activity. The goal of this project is to provide a reasonable expectation that the disposal of the waste is protective of the general public, groundwater resources, air resources, surface water resources, and inadvertent intruders. Achieving this goal will require prediction of contaminant migration from the facilities. This migration is expected to occur primarily via the movement of water through the facilities and the consequent transport of dissolved contaminants in the pore water of the vadose zone. Pacific Northwest National Laboratory (PNNL) assists LMHC in its performance assessment activities. One of PNNL's tasks is to provide estimates of the physical, hydraulic, and transport properties of the materials comprising the disposal facilities and the disturbed region around them. These materials are referred …
Date: December 21, 1999
Creator: Meyer, PD & Serne, RJ
Object Type: Report
System: The UNT Digital Library
Near-field Hydrology Data Package for the Immobilized Low-Activity Waste 2001 Performance Assessment (open access)

Near-field Hydrology Data Package for the Immobilized Low-Activity Waste 2001 Performance Assessment

Near-field Hydrology Data Package for the Immobilized Low-Activity Waste 2001 Performance Assessment
Date: December 21, 1999
Creator: Meyer, Philip D. & Serne, R. Jeffrey
Object Type: Report
System: The UNT Digital Library