Resource Type

16 Matching Results

Results open in a new window/tab.

Sputter Deposition of Metallic Sponges (open access)

Sputter Deposition of Metallic Sponges

Metallic films are grown with a sponge-like morphology in the as-deposited condition using planar magnetron sputtering. The morphology of the deposit is characterized by metallic continuity in three dimensions with continuous porosity on the sub-micron scale. The stabilization of the metallic sponge is directly correlated with a limited range for the sputter deposition parameters of working gas pressure and substrate temperature. This sponge-like morphology augments the features as generally understood in the classic zone models of growth for physical vapor deposits. Nickel coatings are deposited with working gas pressures up to 4 Pa and for substrate temperatures up to 1100 K. The morphology of the deposits is examined in plan and in cross-section with scanning electron microscopy. The parametric range of gas pressure and substrate temperature (relative to absolute melt point) for the deposition processing under which the metallic sponges are produced appear universal for many metals, as for example, including gold, silver, and aluminum.
Date: January 18, 2002
Creator: Jankowski, Alan Frederic & Hayes, Jeffrey P.
System: The UNT Digital Library
2002 Gordon Research Conference on Molecular Evolution (open access)

2002 Gordon Research Conference on Molecular Evolution

Emphasis was placed on current unpublished research and discussion of the future target areas in this field.
Date: January 18, 2002
Creator: unknown
System: The UNT Digital Library
Further studies on hydration of alkynes by the PtCl4-CO catalyst (open access)

Further studies on hydration of alkynes by the PtCl4-CO catalyst

Under CO atmosphere, between 80 and 120 C, a glyme solution of PtCl{sub 4} forms a carbonyl compound that promotes hydration of internal as well as terminal alkynes to give aldehyde-free ketones. The catalytic process depends strongly on the electronic and steric nature of the substrates. Part of the carbonyl functions of the catalyst can be replaced by phosphine ligands. Chiral DIOP reacts with the PtCl{sub 4}-CO compound to give a catalyst that promotes partial kinetic resolution of a racemic alkyne. Replacement of part of the CO by polystyrene-bound diphenylphosphine enables to attach the catalyst to the polymeric support. Upon entrapment of the platinum compound in a silica sol-gel matrix, it reacts as a partially recyclable catalyst. A reformulated mechanism for the PdCl{sub 4}-CO catalyzed hydration is suggested on the basis of the present study.
Date: January 18, 2002
Creator: Israelsohn, Osnat; Vollhardt, K. Peter C. & Blum, Jochanan
System: The UNT Digital Library
Photosubstitution of (fulvalene)tetracarbonyldiruthenium by alkenes and alkynes: First observation of alkyne coupling on fulvalene dimetals and synthesis of a (fulvalene)dimetallacyclopentadiene(alkene) complex (open access)

Photosubstitution of (fulvalene)tetracarbonyldiruthenium by alkenes and alkynes: First observation of alkyne coupling on fulvalene dimetals and synthesis of a (fulvalene)dimetallacyclopentadiene(alkene) complex

None
Date: January 18, 2002
Creator: Chen, Ming-Chou; Eichberg, Michael J.; Vollhardt, K. Peter C.; Sercheli, Ricardo; Wasser, Ian M. & Whitener, Glenn D.
System: The UNT Digital Library
Run scenarios for the Linear Collider (open access)

Run scenarios for the Linear Collider

None
Date: January 18, 2002
Creator: Battaglia, M.; Barron, J.; Dima, M.; Hamilton, L.; Johnson, A.; Nauenberg, U. et al.
System: The UNT Digital Library
Isomerization of linear to angular [3]phenylene and PAHs under flash vacuum pyrolysis conditions (open access)

Isomerization of linear to angular [3]phenylene and PAHs under flash vacuum pyrolysis conditions

None
Date: January 18, 2002
Creator: Dosa, Peter I.; Schleifenbaum, Andreas & Vollhardt, K. Peter C.
System: The UNT Digital Library
Synthesis and crystal structures of (fulvalene)W2(SH)2(CO)6, (fulvalene)W2(mu-S2)(CO)6, and (fulvalene)W2(mu-S)(CO)6-low valent tungsten carbonyl sulfide and disulfide complexes stabilized by the bridging fulvalene ligand (open access)

Synthesis and crystal structures of (fulvalene)W2(SH)2(CO)6, (fulvalene)W2(mu-S2)(CO)6, and (fulvalene)W2(mu-S)(CO)6-low valent tungsten carbonyl sulfide and disulfide complexes stabilized by the bridging fulvalene ligand

None
Date: January 18, 2002
Creator: Capps, Kenneth B.; Bauer, Andreas; Abboud, Khalil; Wasser, Ian M.; Vollhardt, K. Peter C. & Hoff, Carl D.
System: The UNT Digital Library
Manufacture of Large-Aperture Diffractive Optics and Ultrathin Optics for High-Power Laser and Space Applications (open access)

Manufacture of Large-Aperture Diffractive Optics and Ultrathin Optics for High-Power Laser and Space Applications

We have developed equipment and technology for fabricating submicron pitch, high-efficiency diffraction gratings over meter-scale apertures that are used for pulse compression in ultrafast systems around the world. We have also developed wet-etch figuring (WEF) to generate arbitrary continuous contours on ultrathin glass substrates in a closed loop process. The current and future states of these technologies will be discussed.
Date: January 18, 2002
Creator: Britten, J A
System: The UNT Digital Library
Structured Surface Grid Generation on Boundary Represented Geometry (open access)

Structured Surface Grid Generation on Boundary Represented Geometry

Generation of surface meshes is the first step in many grid generation processes. For the generation of block-structured meshes, structured surface meshes have to be generated first. This paper investigates the problem of generating a structured surface mesh across multiple surface patches on an object with the boundary representation and relates the problem to other commonly encountered issues in CAD/CAM. It describes a method for solving the problem. This method is based on initial surface construction, point projection and a mixed model-space and parameter-space based elliptic smoothing.
Date: January 18, 2002
Creator: Chou, J J
System: The UNT Digital Library
Oligocyclopentadienyl transition metal complexes (open access)

Oligocyclopentadienyl transition metal complexes

Synthesis, characterization, and reactivity studies of oligocyclopentadienyl transition metal complexes, namely those of fulvalene, tercyclopentadienyl, quatercyclopentadienyl, and pentacyclopentadienyl(cyclopentadienyl) are the subject of this account. Thermal-, photo-, and redox chemistries of homo- and heteropolynuclear complexes are described.
Date: January 18, 2002
Creator: de Azevedo, Cristina G. & Vollhardt, K. Peter C.
System: The UNT Digital Library
A Rotating Metal Band Target for PION Production at MUON Colliders (open access)

A Rotating Metal Band Target for PION Production at MUON Colliders

A conceptual design is presented for a high power pion production target for muon colliders that is based on a rotating metal band. Three candidate materials are considered for the target band: inconel alloy 718, titanium alloy 6Al-4V grade 5 and nickel. A pulsed proton beam tangentially intercepts a chord of the target band that is inside a 20 Tesla tapered solenoidal magnetic pion capture channel similar to designs previously considered for muon colliders and neutrino factories. The target band has a radius of 2.5 meters and is continuously rotated at approximately 1 m/s to carry heat away from the production region and through a water cooling tank. The mechanical layout and cooling setup of the target are described, including the procedure for the routine replacement of the target band. A rectangular band cross section is assumed, optionally with I-beam struts to enhance stiffness and minimize mechanical vibrations. Results are presented from realistic MARS Monte Carlo computer simulations of the pion yield and energy deposition in the target and from ANSYS finite element calculations for the corresponding shock heating stresses. The target scenario is found to perform satisfactorily and with conservative safety margins for multi-MW pulsed proton beams.
Date: January 18, 2002
Creator: King, B. J.; Simos, N.; Weggel, R. V. & Mokhov, N. V.
System: The UNT Digital Library
Commissioning and operation of the CDF silicon detector (open access)

Commissioning and operation of the CDF silicon detector

The CDF-II silicon detector has been partially commissioned and used for taking preliminary physics data. This paper is a report on commissioning and initial operations of the 5.8m{sup 2} silicon detector. This experience can be useful to the large silicon systems that are presently under construction.
Date: January 18, 2002
Creator: D'Auria, S.
System: The UNT Digital Library
Top results from the Tevatron (open access)

Top results from the Tevatron

This paper summarizes the latest measurements of the properties of the top quark as determined by the CDF and D0 collaborations during the first run of the Fermilab Tevatron p{bar p} collider (1992-1996). Prospects for future measurements of the top quark at the upgraded Tevatron collider are also presented.
Date: January 18, 2002
Creator: Barberis, E.
System: The UNT Digital Library
The CDF-II silicon tracking system (open access)

The CDF-II silicon tracking system

The CDFII silicon tracking system, SVX, for Run II of the Fermilab Tevatron has up to 8 cylindrical layers with average radii spanning from {approx} (1.5 to 28.7) cm, and lengths ranging from {approx} (90 to 200) cm for a total active-area of {approx} 6 m{sup 2} and {approx} 7.2 x 10{sup 5} readout channels. SVX will improve the CDFII acceptance and efficiency for both B and high-Pt physics dependent upon b-tagging. Along with the description of the SVX we report some alignment survey data from the SVX assembly phase and the actual status of the alignment as it results from the offline data analysis. The problems encountered are also reviewed.
Date: January 18, 2002
Creator: al., F. Palmonari et
System: The UNT Digital Library
Characterization of prototype BTeV silicon pixel sensors before and after irradiation (open access)

Characterization of prototype BTeV silicon pixel sensors before and after irradiation

We report on measurements performed on silicon pixel sensor prototypes exposed to a 200 MeV proton beam at the Indiana University Cyclotron Facility. The sensors are of n{sup +}/n/p{sup +} type with multi-guard ring structures and p-stop electrode isolation. Electrical characterization of such devices was performed before and after irradiation up to proton fluence of 4 x 10{sup 14} p cm{sup -2}. We tested pixel sensors fabricated from normal and oxygen-enriched silicon wafers and with two different p-stop isolation layouts: common p-stop and individual p-stop.
Date: January 18, 2002
Creator: al., Maria Rita Coluccia et
System: The UNT Digital Library
Reflections on My Contributions to Particle Physics and Recent Experimental Results From Rhic. (open access)

Reflections on My Contributions to Particle Physics and Recent Experimental Results From Rhic.

My talk today will be composed of two parts. The first part will consist of a summary of some of my experimental contributions over the years. It will not be exhaustive but will highlight the findings that had relevance to the progress of our understanding of particle physics as it has evolved over the years. This section will be divided into three periods: Early, Intermediate and Late, with an in depth discussion of a few of the more significant results. The second part will consist of a discussion of the recently completed Relativistic Heavy Ion Collider (RHIC) machine at Brookhaven National Laboratory (BNL). This will encompass the parameters of the accelerator and some of the interesting and exciting early experimental results emanating from this machine.
Date: January 18, 2002
Creator: Samios, N. P.
System: The UNT Digital Library