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
Absolute CH radical concentrations in rich low-pressure methane-oxygen-argon flames via cavity ringdown spectroscopy of the A transition (open access)

Absolute CH radical concentrations in rich low-pressure methane-oxygen-argon flames via cavity ringdown spectroscopy of the A transition

We measure cavity ringdown spectra of the A{sup 2}{Delta}-X{sup 2}II transition of the methylidyne (CH) radical in a series of rich low-pressure methane-oxygen-argon flames and demonstrate that the technique is sensitive, quantitative, and straightforward in its implementation and interpretation. As a line-of-sight technique, it complements imaging techniques, such as planar laser-induced fluorescence. Our results generally agree with chemical kinetic models for methane oxidation that have appeared in the literature, but suggest some refinements are necessary. Additional examination of the CH + O{sub 2} reaction rate as a function of temperature is advised. Our results are consistent with those of Derzy et al. using the C{sup 2}{Sigma}{sup +}-X{sup 2}II transition for stoichiometric, low-pressure flames which include nitrogen. Our results for rich flames, as with earlier experiments for singlet methylene, suggest that flame chemical kinetic models need to be adjusted to account for flame chemistry for stoichiometries richer than {phi} = 1.5.
Date: November 22, 1999
Creator: John W. Thomas, Jr & McIlroy, Andrew
System: The UNT Digital Library
Assessing the disposal of wastes containing NORM in nonhazardous waste landfills (open access)

Assessing the disposal of wastes containing NORM in nonhazardous waste landfills

In the past few years, many states have established specific regulations for the management of petroleum industry wastes containing naturally occurring radioactive material (NORM) above specified thresholds. These regulations have limited the number of disposal options available for NORM-containing wastes, thereby increasing the related waste management costs. In view of the increasing economic burden associated with NORM management, industry and regulators are interested in identifying cost-effective disposal alternatives that still provide adequate protection of human health and the environment. One such alternative being considered is the disposal of NORM-containing wastes in landfills permitted to accept only nonhazardous wastes. The disposal of petroleum industry wastes containing radium-226 and lead-210 above regulated levels in nonhazardous landfills was modeled to evaluate the potential radiological doses and associated health risks to workers and the general public. A variety of scenarios were considered to evaluate the effects associated with the operational phase (i.e., during landfill operations) and future use of the landfill property. Doses were calculated for the maximally exposed receptor for each scenario. This paper presents the results of that study and some conclusions and recommendations drawn from it.
Date: November 22, 1999
Creator: Smith, K. P.; Blunt, D. L.; Williams, G. P.; Arnish, J. J.; Pfingston, M. R. & Herbert, J.
System: The UNT Digital Library
Conceptual design of a common coil dipole for VLHC (open access)

Conceptual design of a common coil dipole for VLHC

Superconducting magnet technology and cost reduction are key issues in the R and D effort towards a post-LHC, 100 TeV hadron collider. A dipole field of 10-12 T at 4.5 K operating temperature results in acceptable machine length and refrigeration power requirements, and allows taking advantage of synchrotron radiation damping to achieve low beam emittance. In this paper, the conceptual design of a react-and-wind common coil dipole is presented, which aims at these operating parameters with minimum cost and complexity.
Date: November 22, 1999
Creator: Sabbi, G.; Ambrosio, G.; Andreev, N.; Barzi, E.; Ewald, K.; Limon, P. et al.
System: The UNT Digital Library
Design of a new liquid cell for shock experiments (open access)

Design of a new liquid cell for shock experiments

Controlled impact methodology has been used on a powdergun to obtain dynamic behavior properties of Tributyl Phosphate (TBP). A novel test methodology is used to provide extremely accurate equation of state data of the liquid. A thin aluminum plate used for confining the liquid also serves as a diagnostic to provide reshock states and subsequent release adiabats from the reshocked state. Polar polymer, polyvinylidene fluoride (PVDF) gauges and velocity interferometer system for any reflector (VISAR) provided redundant and precise data of temporal resolution to five nanoseconds and shock velocity measurements of better than 1%. The design and test methodologies are presented in this paper.
Date: November 22, 1999
Creator: Reinhart, W. D. & Chhabildas, L. C.
System: The UNT Digital Library
Electro-Osmotic Remediation of Fine-Grained Sediments (open access)

Electro-Osmotic Remediation of Fine-Grained Sediments

The coupled-flow phenomenon, electro-osmosis, whereby water flow results from an applied electrical potential gradient, is being used at Lawrence Livermore National Laboratory to induce water flow through deep (25-40 meters below surface) fine-grained sediments. The scoping work described here lays the groundwork for implementation of this technology to remediate solvent-contaminated clayey zones at the LLNL site. The electro-osmotic conductivity (k{sub e}) measured in-situ between two 37 m deep wells, 3 m apart of 2.3 x 10{sup -9} m{sup 2}/s-V is in good agreement with the value determined from bench-top studies on the core extracted from one of the wells of 0.94 {+-} 0.29 x 10{sup -9} m{sup 2}/s-V. Hydraulic conductivity (k{sub h}) of the same core is measured to be 2.03 {+-} 0.36 x 10{sup -10} m/s. Thus, a voltage gradient of 1 V/cm produces an effective hydraulic conductivity of {approx}1 x 10{sup -7} m/s; an increase in conductivity of nearly three orders of magnitude.
Date: November 22, 1999
Creator: Cherepy, N. J.; McNab, W. W.; Wildenschild, D.; Ruiz, R. & Elsholz, A.
System: The UNT Digital Library
Experimental status of b hadron lifetimes (open access)

Experimental status of b hadron lifetimes

In this paper the authors review the most recent experimental results on the various B hadron species lifetimes obtained at electron-positron machines and at the Tevatron.
Date: November 22, 1999
Creator: Donati, S.
System: The UNT Digital Library
The Intermediate Silicon Layers (ISL) Detector for the Collider Detector at Fermilab (open access)

The Intermediate Silicon Layers (ISL) Detector for the Collider Detector at Fermilab

The Intermediate Silicon Layers detector is part of the CDF upgrade for Run II. The ISL is a large radius (29 cm) silicon tracker with a total active area of about 3.5 m{sup 2}. The conceptual design and the status of the project are reviewed.
Date: November 22, 1999
Creator: Leone, Sandra
System: The UNT Digital Library
Isotopic Tracing of Particulate Matter from a Compression Ignition Engine Fueled with Ethanol-in-Diesel Blends (open access)

Isotopic Tracing of Particulate Matter from a Compression Ignition Engine Fueled with Ethanol-in-Diesel Blends

Accelerator Mass Spectrometry (AMS) was used to investigate the relative contribution to diesel engine particulate matter (PM) from the ethanol and diesel fractions of blended fuels. Four test fuels along with a diesel fuel baseline were investigated. The test fuels were comprised of {sup 14}C depleted diesel fuel mixed with contemporary grain ethanol (>400 the {sup 14}C concentration of diesel). An emulsifier (Span 85) or cosolvent (butyl alcohol) was used to facilitate mixing. The experimental test engine was a 1993 Cummins B5.9 diesel rated at 175 hp at 2500 rpm. Test fuels were run at steady-state conditions of 1600 rpm and 210 ft-lbs, and PM samples were collected on quartz filters following dilution of engine exhaust in a mini-dilution tunnel. AMS analysis of the filter samples showed that the ethanol contributed less to PM relative to its fraction in the fuel blend. For the emulsified blends, 6.4% and 10.3% contributions to PM were observed for 11.5% and 23.0% ethanol fuels, respectively. For the cosolvent blends, even lower contributions were observed (3.8% and 6.3% contributions to PM for 12.5% and 25.0% ethanol fuels, respectively).
Date: November 22, 1999
Creator: Cheng, Adelbert S.; Dibble, Robert W. & Buchholz, Bruce
System: The UNT Digital Library
Long throw and rotary output electro-thermal actuators based on bent-beam suspensions (open access)

Long throw and rotary output electro-thermal actuators based on bent-beam suspensions

This paper reports on significant advances in electrothermal bent beam actuators. Designs for long throw linear and rotary actuators are described. Silicon p++ devices showed 20--30 {mu}m displacements with 150 {micro}N loads at actuation levels of 6--8 V, and 250--300 mW. An electroplated version provided 15 {mu}m displacements at 0.8 V and 450 mW. Inchworm type devices are reported that had linear displacements of 100 {micro}m with 200 {micro}N loads. Refinements in the modeling to account for non-linear thermal expansion coefficients and buckling are also reported.
Date: November 22, 1999
Creator: Park, J.S.; Chu, L.L.; Siwapornsathain, E.; Oliver, A.D. & Gianchandani, Y.B.
System: The UNT Digital Library
Online modeling of the Fermilab accelerators (open access)

Online modeling of the Fermilab accelerators

Access through the Fermilab control system to beam physics models of the Fermilab accelerators has been implemented. The models run on Unix workstations, communicating with legacy VMS-based controls consoles via a relational database and TCP/IP.The client side (VMS) and the server side (Unix) are both implemented in object-oriented C++. The models allow scientists and operators in the control room to do beam physics calculations. Settings of real devices as input to the model are supported, and readings from beam diagnostics may be compared with model predictions.
Date: November 22, 1999
Creator: E. McCrory, O. Krivosheev, L. Michelotti and J-F. Ostiguy
System: The UNT Digital Library
Plutonium silicate alteration phases produced by aqueous corrosion of borosilicate glass. (open access)

Plutonium silicate alteration phases produced by aqueous corrosion of borosilicate glass.

Borosilicate glasses loaded with {approx}10 wt % plutonium were found to produce plutonium-silicate alteration phases upon aqueous corrosion under a range of conditions. The phases observed were generally rich in lanthanide (Ln) elements and were related to the lanthanide orthosilicate phases of the monoclinic Ln{sub 2}SiO{sub 5} type. The composition of the phases was variable regarding [Ln]/[Pu] ratio, depending upon type of corrosion test and on the location within the alteration layer. The formation of these phases likely has implications for the incorporation of plutonium into silicate alteration phases during corrosion of titanate ceramics, high-level waste glasses, and spent nuclear fuel.
Date: November 22, 1999
Creator: Fortner, J. A.; Mertz, C. J.; Bakel, A. J.; Finch, R. J. & Chamerlain, D. B.
System: The UNT Digital Library