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Harmonically excited orbital variations (open access)

Harmonically excited orbital variations

Rephrasing the equations of motion for orbital maneuvers in terms of Lagrangian generalized coordinates instead of Newtonian rectangular cartesian coordinates can make certain harmonic terms in the orbital angular momentum vector more readily apparent. In this formulation the equations of motion adopt the form of a damped harmonic oscillator when torques are applied to the orbit in a variationally prescribed manner. The frequencies of the oscillator equation are in some ways unexpected but can nonetheless be exploited through resonant forcing functions to achieve large secular variations in the orbital elements. Two cases are discussed using a circular orbit as the control case: (1) large changes in orbital inclination achieved by harmonic excitation rather than one impulsive velocity change, and (2) periodic and secular changes to the longitude of the ascending node using both stable and unstable excitation strategies. The implications of these equations are also discussed for both artificial satellites and natural satellites. For the former, two utilitarian orbits are suggested, each exploiting a form of harmonic excitation. 5 refs.
Date: August 6, 1985
Creator: Morgan, T.
System: The UNT Digital Library
Open Cavity Solutions to the Rf in Magnetic Field Problem. (open access)

Open Cavity Solutions to the Rf in Magnetic Field Problem.

It has been observed [1] that breakdown in an 805 MHz pill-box cavity occurs at much lower gradients as an external axial magnetic field is increased. This effect was not observed with on open iris cavity. It is proposed that this effect depends on the relative angles of the magnetic and maximum electric fields: parallel in the pill-box case; at an angle in the open iris case. If so, using an open iris structure with solenoid coils in the irises should perform even better. A lattice, using this principle, is presented, for use in 6D cooling for a Muon Collider. Experimental layouts to test this principle are proposed.
Date: August 6, 2007
Creator: Palmer, R. B.; Berg, J. S.; Fernow, R. C.; Gallardo, J. C. & Kirk, H. G.
System: The UNT Digital Library
Using Ffags in the Creation of Neutrino Beams. (open access)

Using Ffags in the Creation of Neutrino Beams.

A number of accelerator-based facilities have been proposed for the creation of neutrino beams: superbeams, neutrino factories, and beta beams. Fixed field alternating gradient accelerators (FFAGs) have potential uses in all of these facilities. Superbeams and neutrino factories require high power proton drivers for the production of pions; FFAGs can beneficial for accelerating protons for those machines. FFAGs can reduce the cost of accelerating muons in a neutrino factory because they enable the muons to make many passes through the RF cavities and still accelerate rapidly. FFAGs have potential uses in production of radioactive ions for a beta beam facility, since radioactive ions that decay into high energy neutrinos in their rest frame may potentially be produced in a ring, and the large energy acceptance of an FFAG may be useful for maximizing beam lifetime in such a ring. Finally, FFAGs have been contemplated for use in ionization cooling rings for neutrino factories, since the equilibrium distribution in ionization cooling has a large energy spread for which an FFAG's large energy acceptance is needed, and FFAGs may make it feasible to inject and extract from such a ring.
Date: August 6, 2007
Creator: Berg, J. S.
System: The UNT Digital Library
The US Long Baseline Neutrino Experiment Study (open access)

The US Long Baseline Neutrino Experiment Study

The US Long Baseline Neutrino Experiment Study was commissioned jointly by Brookhaven National Laboratory (BNL)and Fermi National Accelerator Laboratory (FNAL) to investigate the potential for future U.S. based long baseline neutrino oscillation experiments using MW class conventional neutrino beams that can be produced at FNAL. The experimental baselines are based on two possible detector locations: (1) off-axis to the existing FNAL NuMI beamline at baselines of 700 to 810 km and (2) NSF's proposed future Deep Underground Science and Engineering Laboratory (DUSEL) at baselines greater than 1000km. Two detector technologies are considered: a megaton class Water Cherenkov detector deployed deep underground at a DUSEL site, or a 100kT Liquid Argon Time-Projection Chamber (TPC) deployed on the surface at any of the proposed sites. The physics sensitivities of the proposed experiments are summarized. We find that conventional horn focused wide-band neutrino beam options from FNAL aimed at a massive detector with a baseline of > 1000km have the best sensitivity to CP violation and the neutrino mass hierarchy for values of the mixing angle {theta}{sub 13} down to 2{sup o}.
Date: August 6, 2007
Creator: Bishai, M.
System: The UNT Digital Library
Multiple-Coincidence Active Neutron Interrogation of Fissionable Materials (open access)

Multiple-Coincidence Active Neutron Interrogation of Fissionable Materials

Using a beam of tagged 14.1 MeV neutrons to probe for the presence of fissionable materials, we have measured n-γ-γ coincidences from depleted uranium (DU). The multiple coincidence rate is substantially above that measured from lead, tungsten, and iron. The presence of coincidences involving delayed gammas in the DU time spectra provides a signature for fissionable materials that is distinct from non-fissionable ones. In addition, the information from the tagged neutron involved in the coincidence gives the position of the fissionable material in all three dimensions. The result is an imaging probe for fissionable materials that is more compact and that produces much less radiation than other solutions.
Date: August 6, 2008
Creator: J.P. Hurley, R.P. Keegan, J.R. Tinsley, R. Trainham, and S.C. Wilde
System: The UNT Digital Library
Photodeposition of Pt on Colloidal CdS and CdSe/CdS Semiconductor Nanostructures (open access)

Photodeposition of Pt on Colloidal CdS and CdSe/CdS Semiconductor Nanostructures

Semiconductor photocatalysis has been identified as a promising avenue for the conversion of solar energy into environmentally friendly fuels, most notably by the production of hydrogen from water.[1-5] Nanometer-scale materials in particular have attracted considerable scientific attention as the building blocks for light-harvesting applications.[6,7] Their desirable attributes include tunability of the optical properties with size, amenability to relatively inexpensive low-temperature processing, and a high degree of synthetic sophistication leading to increasingly complex and multi-functional architectures. For photocatalysis in particular, the high surface-to-volume ratios in nanoscale materials should lead to an increased availability of carriers for redox reactions on the nanoparticle surface. Recombination of photoexcited carriers directly competes with photocatalytic activity.[3] Charge separation is often achieved with multi-component heterostructures. An early example is the case of TiO2 powders functionalized with Pt and RuO2 particles, where photoexcited electrons are transferred to Pt (the reduction site) and holes to RuO2 (the oxidation site).[8] More recently, many colloidally synthesized nanometer-scale metal-semiconductor heterostructures have been reported.[7,9,10] A majority of these structures are made by thermal methods.[7,10] We have chosen to study photochemical formation of metal-semiconductor heterostructures. The detailed understanding of the mechanisms involved in photodeposition of metals on nanometer-scale semiconductors is necessary to enable a …
Date: August 6, 2008
Creator: Dukovic, Gordana; Merkle, Maxwell G.; Nelson, James H.; Hughes, Steven M. & Alivisatos, A. Paul
System: The UNT Digital Library
R AND D TOPICS FOR NEUTRINO FACTORY ACCELERATION. (open access)

R AND D TOPICS FOR NEUTRINO FACTORY ACCELERATION.

The muons in a neutrino factory must be accelerated from the energy of the capture, phase rotation, and cooling systems (around 120 MeV kinetic energy) to the energy of the storage ring (around 25 GeV). This is done with a sequence of accelerators of different types: a linac, one or more recirculating linear accelerators, and finally one or more fixed field alternating gradient accelerators (FFAGs). I discuss the R&D that is needed to arrive at a complete system which we can have confidence will accelerate the beam and for which we can obtain a cost estimate.
Date: August 6, 2007
Creator: SCOTT,J.S.
System: The UNT Digital Library
The Emma Lattice. (open access)

The Emma Lattice.

EMMA is a 10 to 20MeV electron ring designed to test our understanding of beam dynamics in a relativistic linear non-scaling fixed field alternating gradient accelerator (FFAG). I will give a basic review of the EMMA lattice parameters. Then I will review the different lattice configurations that we would like to have for EMMA. Finally, I will briefly discuss the process of commissioning each lattice configuration.
Date: August 6, 2007
Creator: Berg, J. S.
System: The UNT Digital Library
Actinic EUV mask inspection beyond 0.25 NA (open access)

Actinic EUV mask inspection beyond 0.25 NA

Operating at EUV wavelengths, the SEMATECH Berkeley Actinic Inspection Tool (AIT) is a zoneplate microscope that provides high quality aerial image measurements in routine operations for SEMATECH member companies. We have upgraded the optical performance of the AIT to provide multiple image magnifications, and several inspection NA values up to 0.35 NA equivalent (0.0875 mask-side). We report on the improved imaging capabilities including resolution below 100-nm on the mask side (25 nm, 4x wafer equivalent). EUV reticles are intricate optical systems made from of several materials with wavelength-specific optical properties. The combined interactions of the substrate, multilayer-stack, buffer layer and absorber layer produce a reflected EUV optical field that is challenging to model accurately, and difficult to fully assess without actinic at-wavelength inspection. Understanding the aerial image from lithographic printing alone is complicated by photoresist properties. The AIT is now used to investigate mask issues such as amplitude and phase defect printability, pattern repair techniques, contamination, inspection damage, and mask architecture. The AIT has a 6{sup o} illumination angle, and high-resolution exposure times are typically 20 seconds per image. The AIT operates semi-automatically capturing through-focus imaging series with step sizes as small as 0.1 {micro}m (0.5-0.8 {micro}m are typical), and …
Date: August 6, 2008
Creator: Goldberg, Kenneth A.; Mochi, Iacopo; Anderson, Erik H.; Rekawa, Seno B.; Kemp, Charles D.; Huh, S. et al.
System: The UNT Digital Library
A High Resolution Hydrometer Phase Classifier Based on Analysis of Cloud Radar Doppler Spectra. (open access)

A High Resolution Hydrometer Phase Classifier Based on Analysis of Cloud Radar Doppler Spectra.

The lifecycle and radiative properties of clouds are highly sensitive to the phase of their hydrometeors (i.e., liquid or ice). Knowledge of cloud phase is essential for specifying the optical properties of clouds, or else, large errors can be introduced in the calculation of the cloud radiative fluxes. Current parameterizations of cloud water partition in liquid and ice based on temperature are characterized by large uncertainty (Curry et al., 1996; Hobbs and Rangno, 1998; Intriery et al., 2002). This is particularly important in high geographical latitudes and temperature ranges where both liquid droplets and ice crystal phases can exist (mixed-phase cloud). The mixture of phases has a large effect on cloud radiative properties, and the parameterization of mixed-phase clouds has a large impact on climate simulations (e.g., Gregory and Morris, 1996). Furthermore, the presence of both ice and liquid affects the macroscopic properties of clouds, including their propensity to precipitate. Despite their importance, mixed-phase clouds are severely understudied compared to the arguably simpler single-phase clouds. In-situ measurements in mixed-phase clouds are hindered due to aircraft icing, difficulties distinguishing hydrometeor phase, and discrepancies in methods for deriving physical quantities (Wendisch et al. 1996, Lawson et al. 2001). Satellite-based retrievals of cloud …
Date: August 6, 2007
Creator: Luke,E. & Kollias, P.
System: The UNT Digital Library
Uncertainties in the Anti-neutrino Production at Nuclear Reactors (open access)

Uncertainties in the Anti-neutrino Production at Nuclear Reactors

Anti-neutrino emission rates from nuclear reactors are determined from thermal power measurements and fission rate calculations. The uncertainties in these quantities for commercial power plants and their impact on the calculated interaction rates in {bar {nu}}{sub e} detectors is examined. We discuss reactor-to-reactor correlations between the leading uncertainties, and their relevance to reactor {bar {nu}}{sub e} experiments.
Date: August 6, 2008
Creator: Djurcic, Zelimir; Detwiler, Jason A.; Piepke, Andreas; Foster Jr., Vince R.; Miller, Lester & Gratta, Giorgio
System: The UNT Digital Library
Comment on "Paleoclassical Transport in Low-Collisionality Toroidal Plasmas" [Phys. Plasmas 12, 092512 (2005)] (open access)

Comment on "Paleoclassical Transport in Low-Collisionality Toroidal Plasmas" [Phys. Plasmas 12, 092512 (2005)]

None
Date: August 6, 2007
Creator: LoDestro, L.
System: The UNT Digital Library
SENSITIVITIES OF FUTURE LONG BASELINE EXPERIMENTS IN THE U.S. (open access)

SENSITIVITIES OF FUTURE LONG BASELINE EXPERIMENTS IN THE U.S.

Sensitivities to neutrino oscillation parameters for possible very long baseline neutrino oscillation experiments are discussed. The reach for observing a non-zero mixing angle {theta}{sub 13}, establishing CP violation and determining the mass hierarchy are compared between various experimental options. Different possibilities for neutrino beams are briefly described, as well as the assumptions about the performance of a large water Cherenkov and liquid Argon detector.
Date: August 6, 2007
Creator: DIERCKXSENS,M.
System: The UNT Digital Library
X-ray microscopy using grazing-incidence reflection optics (open access)

X-ray microscopy using grazing-incidence reflection optics

The Kirkpatrick-Baez microscopes are described along with their role as the workhorse of the x-ray imaging devices. This role is being extended with the development of a 22X magnification Kirkpatrick-Baez x-ray microscope with multilayer x-ray mirrors. These mirrors can operate at large angles, high x-ray energies, and have a narrow, well defined x-ray energy bandpass. This will make them useful for numerous experiments. However, where a large solid angle is needed, the Woelter microscope will still be necessary and the technology needed to build them will be useful for many other types of x-ray optics.
Date: August 6, 1981
Creator: Price, R.H.
System: The UNT Digital Library
Analytical cytology applied to detection of induced cytogenetic abnormalities (open access)

Analytical cytology applied to detection of induced cytogenetic abnormalities

Radiation-induced biological damage results in formation of a broad spectrum of cytogenetic changes such as translocations, dicentrics, ring chromosomes, and acentric fragments. A battery of analytical cytologic techniques are now emerging that promise to significantly improve the precision and ease with which these radiation induced cytogenetic changes can be quantified. This report summarizes techniques to facilitate analysis of the frequency of occurrence of structural and numerical aberrations in control and irradiated human cells. 14 refs., 2 figs.
Date: August 6, 1987
Creator: Gray, J.W.; Lucas, J.; Straume, T. & Pinkel, D.
System: The UNT Digital Library
Microhardness Tests for High-Energy Neutron-Source Experiments (open access)

Microhardness Tests for High-Energy Neutron-Source Experiments

In a development effort to extract mechanical property information from miniature specimens, standard diamond pyramid microhardness (DPH) tests have been conducted at Hanford Engineering Development Laboratory (HEDL) on specimens irradiated in RTNS-II; and techniques to extend the information available from microhardness tests have been developed at the University of California, Santa Barbara (UCSB). In tests at HEDL, radiation hardening has only been observed in relatively pure materials irradiated to neutron fluences less than 4 x 10/sup 17/ n/cm/sup 2/. In copper, specifically, a proportional increase in the DPH with neutron fluence has been observed, and this microhardness increase has been correlated with an increase in the 0.2 percent offset yield strength. At UCSB it has been found that hardness and microhardness data obtained with spherical indenters can be used to determine the true stress-true plastic strain relationship of the test material; moreover, it has been found that features of the indentation lip geometry can be used to characterize localized flow phenomena like Lueders strain in steel. Consequently, microhardness test techniques appear attractive for small specimen test applications.
Date: August 6, 1981
Creator: Panayotou, N. F. & Lucas, G. E.
System: The UNT Digital Library
Processing of high salinity brines for subsurface injection (open access)

Processing of high salinity brines for subsurface injection

Different chemical pretreatments and filtration methods were evaluated as a possible means of clarifying and improving the injectivity of hypersaline brines. Six different downflow media combinations were evaluated over three geopressurized sites, using test data from 4 inch diameter filters. Also, tests were conducted with one hollow fiber ultrafilter unit and two types of disposable cartridge filters. The test procedures are mentioned briefly. (MHR)
Date: August 6, 1979
Creator: Thompson, R.E. & Raber, E.
System: The UNT Digital Library
X-Ray Diffraction Properties and Applications of Layered Synthetic Microstructures in the 1 to 10 Angstrom Region (open access)

X-Ray Diffraction Properties and Applications of Layered Synthetic Microstructures in the 1 to 10 Angstrom Region

Layered synthetic microstructures have been built and tested for use as medium-resolution x-ray diffraction monochromators, in the 1 to 10 angstrom wavelength region. They can be employed to good advantage in spectrometry and imaging instruments that are used to determine the nature of the x-ray emission of high-temperature plasmas. When the micro-structures are used in spectrometers, we find that they gather much more light than natural crystals and are not troubled by high order diffraction response, yet have better spectral resolution than that provided by spectrometer channels formed by Ross filter or filter/fluorescer techniques. For use in imaging instruments such as the grazing-incidence reflection Kirkpatrick-Baez microscope, the microstructures provide high reflectivity at wavelengths shorter than the practical limit of total external reflection. We will present calibration data that describes the diffraction properties and piece-to-piece uniformity of microstructures built especially for use in the 1 to 10 angstrom region. We will also describe in detail two instruments that will be used at the Shiva laser system to determine the spectral and spatial distributions of x-rays radiated by inertial confinement fusion targets.
Date: August 6, 1980
Creator: Koppel, L. & Barbee, T. W., Jr.
System: The UNT Digital Library
Progress in Inertial Confinement Fusion at Lawrence Livermore National Laboratory (open access)

Progress in Inertial Confinement Fusion at Lawrence Livermore National Laboratory

The goals of the Inertial Fusion Program at the Lawrence Livermore National Laboratory are to study matter under extreme conditions of temperature and pressure and to produce fusion energy from inertially confined fusion fuel. With the conclusion of recent multi-kilojoule 0.53 ..mu..m experiments on Novette, we have demonstrated vastly improved plasma conditions compared to those previously obtained at LLNL with similar energies at 1.06 ..mu..m and elsewhere with 10 ..mu..m radiation. The lower preheat environment obtainable with short wavelength light has led to 3X improvements in the compression of targets on Novette compared to similar targets on Shiva with 1.06 ..mu..m. Subsequent experiments on Nova with short wavelength light will begin in 1985. They are expected to demonstrate the necessary compression conditions required for high gain fusion to occur when irradiated with a multi-megajoule driver. These recent results, together with improved calculations, and innovations in driver and reactor technology, indicate that high gain inertial fusion will occur and is a viable candidate for fusion power production in the future.
Date: August 6, 1984
Creator: Holzrichter, John F.
System: The UNT Digital Library
Potential-induced nanoclustering of metallic catalysts during electrochemical CO2 reduction (open access)

Potential-induced nanoclustering of metallic catalysts during electrochemical CO2 reduction

This article reveals the unique and general degradation mechanism of metallic nanocatalysts during electrochemical CO₂ reduction, exemplified by different sized copper nanocubes.
Date: August 6, 2018
Creator: Huang, Jianfeng; Hörmann, Nicolas; Oveisi, Emad; Loiudice, Anna; De Gregorio, Gian Luca; Andreussi, Oliviero et al.
System: The UNT Digital Library
2010 GRC VIBRATIONAL SPECTROSCOPY AUGUST 1 - AUGUST 6, 2010 (open access)

2010 GRC VIBRATIONAL SPECTROSCOPY AUGUST 1 - AUGUST 6, 2010

The Vibrational Spectroscopy conference focuses on using vibrational spectroscopy to probe structure and dynamics of molecules in gases, liquids, and at interfaces. The conference explores the wide range of state-of-the-art techniques based on vibrational motion. These techniques span the fields of time-domain, high-resolution frequency-domain, spatially-resolved, nonlinear and multidimensional spectroscopies. The conference highlights the application of these techniques in chemistry, materials, biology, and medicine. The theory of molecular vibrational motion and its connection to spectroscopic signatures and chemical reaction dynamics is the third major theme of the meeting. The goal is to bring together a collection of researchers who share common interests and who will gain from discussing work at the forefront of several connected areas. The intent is to emphasize the insights and understanding that studies of vibrations provide about a variety of molecular systems ranging from small polyatomic molecules to large biomolecules and nanomaterials.
Date: August 6, 2010
Creator: Pate, Brooks
System: The UNT Digital Library
Plastic Behavior of Polycrystalline Tantalum in the 5 X 10^7/S Regime (open access)

Plastic Behavior of Polycrystalline Tantalum in the 5 X 10^7/S Regime

The goal of this experiment is to investigate the plastic response of Tantalum to dynamic loading at high strain rates. The samples used were derived from high purity rolled plate, polished down to thicknesses in the range 25-100 {micro}m. Dynamic loading was applied by direct laser ablation of the sample, with pulses up to 10 ns long, at the Jupiter Laser Facility. The elastic-plastic wave structure was measured using two line VISAR systems of different sensitivity, and strain rates were inferred from the rise time of the waves. The elastic wave amplitudes indicated flow stresses between 2 and 3 GPa, depending on the sample thickness. Samples were recovered for post-shot metallographic analysis.
Date: August 6, 2011
Creator: Hammel, B. D.; Swift, D. C.; El-Dasher, B. S.; Kumar, M.; Collins, G. W. & Florando, J.
System: The UNT Digital Library
Assembly and Packaging of a Wireless, Chronically-Implantable Neural Prosthetic Device (open access)

Assembly and Packaging of a Wireless, Chronically-Implantable Neural Prosthetic Device

None
Date: August 6, 2012
Creator: Shah, K G; DeLima, T; Benett, W; Felix, S; Sheth, H; Tolosa, V et al.
System: The UNT Digital Library
2010 ELECTRODEPOSITION GORDON RESEARCH CONFERENCE, AUGUST 1-6, 2010 (open access)

2010 ELECTRODEPOSITION GORDON RESEARCH CONFERENCE, AUGUST 1-6, 2010

The 2010 Gordon Conference on Electrodeposition will present cutting-edge research on electrodeposition with emphasis on (i) advances in basic science, (ii) developments in next-generation technologies, and (iii) new and emerging areas. The Conference will feature a wide range of topics, from atomic scale processes, nucleation and growth, thin film deposition, and electrocrystallization, to applications of electrodeposition in devices including microelectronics, solar energy, and power sources. The Conference will bring together investigators from a wide range of scientific disciplines, including chemical engineering, materials science and engineering, physics, and chemistry. The Conference will feature invited speakers at the forefront of the field, and a late-breaking news session that will provide the opportunity for graduate students, post-docs, and junior faculty to participate. The collegial atmosphere of this Conference, with scientific talks and poster sessions, as well as opportunities for informal gatherings in the afternoons and evenings, provides an avenue for scientists from different disciplines to discuss current issues and promotes cross-disciplinary collaborations in the various research areas represented. The Conference will be held at Colby-Sawyer College, located in the Mt. Kearsarge-Lake Sunapee Region of New Hampshire. The surrounding mountains, forests, and lakes provide a beautiful setting for this conference. The attendance is limited …
Date: August 6, 2010
Creator: Searson, Peter
System: The UNT Digital Library